Environmental Nanotechnology Volume 5 (Environmental Chemistry for a Sustainable World, 37) 3030730093, 9783030730093

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Environmental Chemistry for a Sustainable World 37

Nandita Dasgupta Shivendu Ranjan Eric Lichtfouse Bhartendu Nath Mishra   Editors

Environmental Nanotechnology Volume 5

Environmental Chemistry for a Sustainable World Volume 37

Series Editors Eric Lichtfouse , Aix Marseille University, CNRS, IRD, INRA, Coll France, CEREGE, Aix en Provence, France Jan Schwarzbauer, RWTH Aachen University, Aachen, Germany Didier Robert, CNRS, European Laboratory for Catalysis and Surface Sciences, Saint-Avold, France

Environmental chemistry is a fast developing science aimed at deciphering fundamental mechanisms ruling the behaviour of pollutants in ecosystems. Applying this knowledge to current environmental issues leads to the remediation of environmental media, and to new, low energy, low emission, sustainable processes. The topics that would be covered in this series, but not limited to, are major achievements of environmental chemistry for sustainable development such as nanotech applications; biofuels, solar and alternative energies; pollutants in air, water, soil and food; greenhouse gases; radioactive pollutants; endocrine disruptors and other pharmaceuticals; pollutant archives; ecotoxicology and health risk; pollutant remediation; geoengineering; green chemistry; contributions bridging unexpectedly far disciplines such as environmental chemistry and social sciences; and participatory research with end-­users. The book series will encompass all scientific aspects of environmental chemistry through a multidisciplinary approach: Environmental Engineering/Biotechnology, Waste Management/Waste Technology, Pollution, general, Atmospheric Protection/ Air Quality Control/Air Pollution, Analytical Chemistry. Other disciplines include: Agriculture, Building Types and Functions, Climate Change, Ecosystems, Ecotoxicology, Geochemistry, Nanochemistry, Nanotechnology and Microengineering, Social Sciences. The aim of the series is to publish 2 to 4 book per year. Audience: Academic/Corporate/Hospital Libraries, Practitioners / Professionals, Scientists / Researchers, Lecturers/Tutors, Graduates, Type of books (edited volumes, monographs, proceedings, textbooks, etc.). Edited volumes: List of subject areas the series will cover: • Analytical chemistry, novel methods • Biofuels, alternative energies • Biogeochemistry • Carbon cycle and sequestration • Climate change, greenhouse gases • Ecotoxicology and risk assessment • Environmental chemistry and the society • Genomics and environmental chemistry • Geoengineering • Green chemistry • Health and environmental chemistry • Internet and environmental chemistry • Nanotechnologies • Novel concepts in environmental chemistry • Organic pollutants, endocrine disrupters • Participatory research with end-­users • Pesticides • Pollution of water, soils, air and food • Radioactive pollutants • Remediation technologies • Waste treatment and recycling • Toxic metals More information about this series at http://www.springer.com/series/11480

Nandita Dasgupta  •  Shivendu Ranjan Eric Lichtfouse  •  Bhartendu Nath Mishra Editors

Environmental Nanotechnology Volume 5

Editors Nandita Dasgupta Department of Biotechnology Institute of Engineering and Technology Lucknow, Uttar Pradesh, India Eric Lichtfouse Aix Marseille University CNRS, IRD, INRA, Coll France, CEREGE Aix en Provence, France

Shivendu Ranjan Faculty of Engineering and the Built Environment University of Johannesburg Johannesburg, Gauteng, South Africa Bhartendu Nath Mishra Department of Biotechnology Institute of Engineering and Technology Lucknow, Uttar Pradesh, India

ISSN 2213-7114     ISSN 2213-7122 (electronic) Environmental Chemistry for a Sustainable World ISBN 978-3-030-73009-3    ISBN 978-3-030-73010-9 (eBook) https://doi.org/10.1007/978-3-030-73010-9 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

We dedicate this book to those who are affected by environmental hazards. We hope that this book may be a small contribution to improving their quality of life

This Environment – Think Nanomaterials– Dr. Nandita Dasgupta

Preface

Total environment is an important approach that is vital for good health of human mankind as well as for food and agriculture in the context of health, sustainable growth, and efficient agro-food product development. As a consequence, novel technologies are emerging fast, and environmental nanotechnology is one among them. In particular, issues of both air and water pollution can be solved by environmental nanotechnologists, which include nanobioremediation, nanonutraceuticals, nanobiosensors, and nanodegradation. This book is the second of several volumes on Environmental Environmental Nanotechnology, which is published in series Environmental Chemistry for a Sustainable World. In Chap. 1, Awang et al. explain the synthesis of nanomaterials, mainly the green synthesis of inorganic nanomaterials. In Chap. 2, Zhao and Hu review the resistive and capacitive measurement of nano-based biosensors. In Chap. 3, Bhattacharjee and Bandyopadhyay explain the efficient delivery of nutraceutical with the help of nanovehicles. In Chap. 4, Agboola et  al. review nanopharmaceuticals as well as their health benefits and the toxic impact of heavy metal nanomaterials. In Chap. 5, Cheng et al. explain molecularly imprinted polymeric nanocomposites. In Chap. 6, Yilmaz and Soylak expound critical and comparative comments on nano-biosensors and nano-aptasensors. In Chap. 7, Cheng et al. point out the applications of nanotechnology for the remediation and purification of water and have mainly focussed on drinking water. In Chap. 8, D’Acunto provide a brief overview about polymers– metal nanoparticles. In Chap. 9, Gandhi et al. present a comprehensive review on plasmonic nanoparticle-based sensors and have hypothesized the future applications of these sensors in environment, which can be plausible in near future. Thanks for reading. Lucknow, India Johannesburg, South Africa Aix en Provence, France Lucknow, India

Nandita Dasgupta Shivendu Ranjan Eric Lichtfouse Bhartendu Nath Mishra

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Contents

1 Nanocellulose-Based Materials for Heavy Metal Removal from Wastewater ����������������������������������������������������������������������������������������������    1 Nor Asikin Awang, Wan Norharyati Wan Salleh, Norhaniza Yusof, Zulhairun Abdul Karim, and Ahmad Fauzi Ismail 2 Visible-Light-Responsive Heterostructured Nanophotocatalysts for Organic Pollutants Decomposition ��������������������������������������������������   35 Dian Zhao and Yong Hu 3 Conductive Polymer Nanobiosensors����������������������������������������������������   85 Mitradip Bhattacharjee and Dipankar Bandyopadhyay 4 Fabrication and Potential Applications of Nanoporous Membranes for Separation Processes����������������������������������������������������  119 Oluranti Agboola, Patricia Popoola, Rotimi Sadiku, Samuel Eshorame Sanni, Damilola Elizabeth Babatunde, Ayodeji Ayoola, and Olubunmi Grace Abatan 5 Nanomaterials for Effective Control of Algal Blooms in Water����������  173 Rong Cheng, Liang-jie Shen, Shao-yu Xiang, Dan-yang Dai, and Xiang Zheng 6 Nanotechnological Developments in Nanofiber-Based Membranes Used for Water Treatment Applications ��������������������������  205 Erkan Yilmaz and Mustafa Soylak 7 Fe-Based Nanomaterials for Removing the Environmental Endocrine Disrupting Chemicals in Water: A Review ������������������������  261 Rong Cheng, Mi Kang, Lei Shi, Jin-lin Wang, Xiang Zheng, and Jian-long Wang 8 Plasmonics, Vibrational Nanospectroscopy and Polymers������������������  293 Mario D’Acunto

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9 Phyto-Nanosensors: Advancement of Phytochemicals as an Electrochemical Platform for Various Biomedical Applications ��������  311 Mansi Gandhi, Shiao-Shing Chen, Saikat Sinha Ray, Nilesh Kumar Jaiswal, and Shivendu Ranjan 10 Nano-Adsorbents in Wastewater Treatment for Phosphate and Nitrate Removal��������������������������������������������������������������������������������  339 Nur Diyana Suzaimi, Pei Sean Goh, Nik Ahmad Nizam Nik Malek, Be Cheer Ng, and Ahmad Fauzi Ismail

About the Editors

Nandita  Dasgupta  has completed her B.Tech and Ph.D. from VIT University, Vellore, India, and is Elected Fellow (FBSS) of Bose Science Society. She has working exposure in micro/nanoscience and is currently working as Assistant Professor at Department of Biotechnology, Institute of Engineering and Technology, Lucknow, India. Earlier at LV Prasad Eye Institute, Bhubaneswar, India, she has worked on mesenchymal stem cell–derived exosomes for the treatment of uveitis. She has exposure of working at university, research institutes, and industries including VIT University, Vellore, Tamil Nadu, India; CSIR-Central Food Technological Research Institute, Mysore, India; Uttar Pradesh Drugs and Pharmaceutical Co. Ltd., Lucknow, India; Indian Institute of Food Processing Technology (IIFPT), Thanjavur, India; and Ministry of Food Processing Industries, Government of India. At IIFPT, Thanjavur, she was involved in a project funded by a leading pharmaceutical company, Dr. Reddy’s Laboratories, and has successfully engineered microvehicles for model drug molecules. Her areas of interest include micro/nanomaterial fabrication and its applications in various fields such as biomedicines, food, environment, and agriculture. She is the associate editor of Environmental Chemistry Letters – a Springer journal of 3.2 impact factor – and also serving as editorial board member and referee for reputed international peer-reviewed journals. She has received several awards and recognitions from different national and international organizations.

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Shivendu  Ranjan  has completed his B.Tech and Ph.D. in Biotechnology from VIT University, Vellore, India, and working in the area of nano(bio)technology. He is Elected Fellow of Bose Scientific Society (FBSS). He is currently working as Senior Research Associate at University of Johannesburg, South Africa. His research interests are multidisciplinary and include micro/nanobiotechnology, nano-toxicology, environmental nanotechnology, nanomedicine, and nanoemulsions. He is an associate editor of Environmental Chemistry Letters – a Springer journal of 5.922 impact factor – and an editorial board member in Biotechnology and Biotechnological Equipment (Taylor and Francis, USA). Eric  Lichtfouse  PhD, born in 1960, is an Environmental Chemist working at the University of Aix-Marseille, France. He has invented carbon-13 dating. He is teaching scientific writing and communication and has published the book Scientific Writing for Impact Factor Journals, which includes a new tool – the micro article – to identify the novelty of research results. He is Founder and Chief Editor of scientific journals and series in environmental chemistry and agriculture. He founded the European Association of Chemistry and the Environment. He received the Analytical Chemistry Prize by the French Chemical Society, the Grand Prize of the Universities of Nancy and Metz, and a Journal Citation Award by the Essential Indicators. Bhartendu  Nath  Mishra  is Professor of Biotech­ nology at Institute of Engineering and Technology, Lucknow and Dean of Research & Development and Industrial Consultancy at Dr. A.P.J. Abdul Kalam Technical University, Lucknow. He has research interest in bioreactor engineering for metabolites production and waste management, 3D bioprinting and microfluidic devices, host microbe interaction, bioinformatics and nanotechnology. He has published 100+ research articles in reputed journals. He has supervised 200+ M.Tech. and 14 Ph.D. theses and mentored 4 Postdoctoral students. His research contributions were

About the Editors

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covered by the media. He is an elected Life member of The National Academy of Sciences, India (NASI), Prayagraj. He has been a member of Core Group on Biotechnology, Council of Science & Technology, UP, India for nearly a decade. He has received many honors/ awards including Vishisht Samman for Outstanding Research and Development work in the area of Environment in 2010, Excellence in Innovation in Technical Education award in 2014 and Outstanding Contribution in Education award in 2015.

Chapter 1

Nanocellulose-Based Materials for Heavy Metal Removal from Wastewater Nor Asikin Awang, Wan Norharyati Wan Salleh, Norhaniza Yusof, Zulhairun Abdul Karim, and Ahmad Fauzi Ismail

Abstract  Water contaminated with heavy metals kept increasing due to the high population and production of wastewater generation. Numerous techniques and materials have been manipulated in order to minimize the problems to treat the present of heavy metals in wastewaters. The advancement of nanocellulose has attracted noteworthy attention among researchers since it has shown its valuable potentials, including renewability, biodegradability, high strength and stiffness. The great properties make nanocellulose as promising based materials to be implemented in heavy metals removal. In general, nanocellulose can be extracted from different kinds of cellulose resources. In this chapter, the production, modification and application of three types of nanocellulose, which are cellulose nanocrystalline (CNC), cellulose nanofibrils (CNF) and bacteria cellulose (BC) have been explored. We highlighted on the research endeavor to improve the properties of the nanocellulose especially in terms of modification in order to meet the requirement for the materials to be applied in wastewater treatment. In detail, this paper discusses the application of nanocellulose under various kinds of modification to suit heavy metals removal from wastewater. Keywords  Nanocellulose · Nanocellulose-based materials · Cellulose nanocrystalline · Cellulose nanofibrils · Bacteria cellulose · Acid hydrolysis · Oxidation · Esterification · Heavy metals · Wastewater treatment

N. A. Awang · W. N. W. Salleh (*) · N. Yusof · Z. A. Karim · A. F. Ismail (*) Advanced Membrane Technology Research Centre (AMTEC), Faculty of Chemical and Energy Engineering (FCEE), Universiti Teknologi Malaysia, Johor Bahru, Malaysia e-mail: [email protected]; [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_1

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1.1  Introduction Water scarcity affects both social and economic sectors, and threatens the sustainability of the natural resources base. Addressing water scarcity requires an intersectoral and multidisciplinary approach in order to maximize economic and social welfare in an equitable manner, without compromising the sustainability of vital ecosystems. Effluents that come from various kinds of industrials fields contain many types of contaminants, which contribute to serious environmental pollutions. Normally, effluents in water are composed of toxic heavy metal ions, inorganic anions, and organic compounds such as dyes, phenols, pesticides and other sustained organic pollutants (Annadurai et al. 2002; Hokkanen et al. 2013, 2016a, b). The most common heavy metals found in the wastewater systems are cadmium, lead, zinc, copper, nickel and mercury. Unlike organic contaminants, heavy metals posses toxic, carcinogenic and non-biodegradable properties, which have high possibility to accumulate in living organisms. Discharge of these pollutants into water systems will negatively affect the environment, especially aquatic organisms. Due to high solubility of these heavy metals into aquatic environment, they can be easily absorbed by aquatic livings. Once these pollutants get involved into food chain, they have high chance to accumulate in human body, thus will lead to health problems, since high toxic content will deteriorate body tissues (Barakat 2011; Riaz et  al. 2016). For instance, high exposure toward cadmium will give nephrotoxic effects, leading to bone damage as long term exposure effects. According to U.S. Environmental Protection Agency, cadmium is likely to contribute to human carcinogen. Other than that, although zinc is one of the essential elements that are responsible for physiological function in our body, if it exceeds the bodily needs, it can cause stomach cramps, skin irritations, vomiting and anemia. Meanwhile, lead can cause kidney damage, anemia and toxicity to the reproductive and cardiovascular systems (Abdelwahab et  al. 2015; Fu and Wang 2011; Wan Ngah and Hanafiah 2008; Yakout et al. 2016; Zhang et al. 2016). Due to the adverse effect towards human and environment, it is important to find the preventive measures to minimize and fully remove these pollutants before they are discharged into the environment. According to International Agency for Research on the topic of cancer, arsenic is classified as Class A carcinogenic heavy metals. As it leaches into soils and minerals, it will naturally enter into aqueous systems. If the content exceeds the Maximum Contaminated Level (MCL) standard of 10μd dm−3, it will degrade human health. Human risk caused by arsenic contaminant have been reported in the regions of North America, India and other Europe countries (Ociński et al. 2016). Table 1.1 shows the Maximum Contaminated Level (MCL) standards for some hazardous heavy metals, as established by United State Environmental Protection Agency, USEPA (Raouf and Rahiem 2017). Environmental sustainability, industrial ecology, eco-efficiency and green chemistry have become additional salient points in approaching the evolution of new materials and product from renewable resources. Naturally derived and renewable materials have become the main focus among researchers to be applied in many

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Table 1.1  The Maximum Contaminated Level (MCL) standards for most hazardous heavy metals (Raouf and Rahiem 2017) Heavy metal Arsenic Cadmium Chromium Copper Nickel Zinc Lead Mercury

Toxicities Skin manifestations, visceral cancers, vascular disease Kidney damage, renal disorder, human carcinogen Headache, diarrhea, nausea. Vomiting, carcinogen Liver damage, Wilson disease, insomnia Dermatitis, nausea, chronic asthma, coughing, human carcinogen Depression, lethargy, neurological signs and nervous system Damage the fetal brain, disease of the kidneys, circulatory system and nervous system Rheumatoid arthritis, and disease of the kidneys, circulatory system and nervous system

MCL (mg/L) 0.05 0.01 0.05 0.25 0.20 0.80 0.006 0.00003

applications due to their environmentally friendly and natural properties. Cellulose has been perceived as capable candidate in environmental pollutant removal. Cellulose was first documented in 1839 by three members of the French Academy of Science writing the report on the work carried out by French Chemist Anselme Payen in 1838 related to the composition of plant tissues and woody materials (Eyley and Thielemans 2014). Cellulose is the most abundant renewable natural biopolymer that is mostly present in living species, especially in plants, animals and also bacteria (de Souza Lima and Borsali 2004; Nyoo et al. 2017). In plants, cellulose can exist in pure form but normally present together with hemicelluloses, lignins and other extractives. The content of cellulose varies in different types of cellulose sources such as bagasse (35–45  wt%), bamboo (40–55  wt%), straw (40–50  wt%), flax (70–80  wt%), hemp (75–80  wt%), jute (60–65  wt%), kapok (70–75 wt%), and rame (70–75 wt%). Cellulose also can be obtained from bacteria and green algae such as Valonia ventricosa, Chaetamorpha melagonicum, Glaucocystis (Heinze 2015). Cellulose is a linear non-branched polysaccharides with molecular formula (C6H10O5)n, where n represents the repeating unit of monomeric β-D glucopyranose units; note that the value of n differs since it takes into account the sources of the purified cellulose (Suhas et al. 2016; S. Wang et al. 2016). The structure of the cellulose is illustrated in Fig. 1.1. The β-D glucose units are united together via covalent bond that is located between the equatorial OH group of C-4 and C-1 carbon atom (Chen et  al. 2014; Rosli et  al. 2014; Wojnárovits et al. 2010). The distinctive structure of cellulose is made up of repeating D-glucopyranose rings that are joined together through β-(1–4)-glycosidic links, as shown in Fig. 1.1. Each monomer of the cellulose consists of three hydroxyl groups which are located at C-2, C-3 and C-6 (primary hydroxyl group). These hydroxyl groups are responsible for the reaction of cellulose (Afizah et al. 2015). The glucose unit of the cellulose structure which consists of –CH2OH groups that are located above and below the plane allows the formation of long and un-branched chain. Since there is no side chain, the cellulose is formed in organized structure. All of these three hydroxyl

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Fig. 1.1  The schematic of the cellulose structure with the illustration of intramolecular and intermolecular hydrogen bond in crystalline region. (Adapted from Lin and Dufresne 2014)

groups tend to form two types of hydrogen bonds, which are intermolecular and intramolecular hydrogen bonds. Intermolecular hydrogen bonds of the cellulose refer to the bond that exists between the cellulose structure with other polymer chain, while intramolecular hydrogen bonds connect the D-glucopyranose rings within the polymer chain (Abdul Khalil et al. 2012). The cellulose molecules will aggregate together to form micro fibrils which are arranged in highly ordered (crystalline), repeatedly with less ordered (amorphous) regions (Chen et al. 2014). Monomeric β-D glucopyranose in wood pulps are typically 300–1700  units, while cotton fibers and bacterial cellulose consist of 800–10,000 units. Agro waste materials such as rise husk and wheat husk contain approximately up 7000  units (Kumar et al. 2017). Cellulose can exists in four main different polymorphs labeled as cellulose I, II, III and IV. Cellulose I refer to original cellulose that naturally exists in nature sources such as plants. This kind of cellulose has two different allomorphs which are Iα and Iβ. Cellulose II is the most stable crystalline form that can be produced via re-crystallization or mercerization with aqueous sodium hydroxide (Aulin et al. 2009; Siqueira et al. 2009). These two forms of cellulose, which are cellulose I and cellulose II are different in terms of their structure, which is in the form of chain in parallel structure in cellulose I, while in cellulose II, the chain is maintained in antiparallel direction. The transformation of cellulose I into cellulose II can be achieved via regeneration or mercerization process by using dissolution system via NaOH/urea (Mohamed et al. 2015), ionic liquid dissolution system such as 1-ethyl3-methylimidazolum acetate ([C2mim]OAc) (Livazovic et  al. 2015), or 1-ethyl3-methylimidazolium chloride (EMIMCl) (Cao et al. 2009; Soheilmoghaddam et al. 2014). Meanwhile, cellulose IIII and IIIII can be isolated via ammonia treatment of cellulose I and II, respectively. Cellulose type IIII refers to cellulose that is fabricated from cellulose type I, while cellulose type IIIII is isolated from cellulose type I. The final product from the isolation of cellulose III is cellulose IV (Lavoine et al. 2012). Cellulose models with different symmetry are presented in Fig. 1.2. Nanocellulose which is highlighted as natural nano-scale material exhibits a variety of features which make it different from traditional materials; encompassing

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Fig. 1.2  Models of (a) cellulose Iβ, (b) cellulose II, (c) cellulose IIII and (d) cellulose IVI with different symmetries. (Adapted from Zugenmaier 2001)

special morphology and geometrical dimension, crystallinity, high specific surface area, rheological properties, liquid crystalline behavior, alignment and orientation, mechanical augmentation, barrier properties, surface chemical properties, biocompatibility, biodegradability, short of toxicity, and low cost (Bagheri et  al. 2017; Flauzino Neto et al. 2013; Lin and Dufresne 2014). Nanocellulose-based materials are promising for wide application in industries is due to its properties such as high mechanical strength and low density (1.566 g cm−3) (Henrique et al. 2013; Mesquita et al. 2010). The main source of nanocellulose is wood pulp (Lavoine et al. 2012; Samir et al. 2004a, b). Nanocellulose materials have the ability to form hydrogen bonds to create interparticle network formation, which is related to the formation of the structure of the cellulose (Ahmed et  al. 2005; Eyley and Thielemans 2014; Rowan et al. 2010; Siqueira et al. 2009). This chapter reviews a recent study on the utilization of nanocellulose in heavy metals removal. Due to its nature and properties, nanocellulose is can be applied in wastewater treatment, especially to separate metal ions before being discharged into the environment.

1.2  Types of Nanocellulose Nanocellulose can be sourced from many kinds of cellulosic materials with dimension of less than or equal to 100 nm (Khalil et al. 2014). Cellulose can be refined from plant fiber by applying alkali extraction and delignification/bleaching

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Table 1.2  Types of nanocellulose, identical terms of nanocellulose, sources and average sizes (Brinchi et al. 2013) Types of nanocellulose Cellulose nanocrystalline (CNC)

Identical terms Cellulose nanocrystals, nanocrystalline cellulose, crystallites, whiskers, rod like cellulose microcrystals

Sources Wood, cotton, hemp, flax, wheat straw, rice straw, mulberry bark, ramie, MCC, avicel, tunicin, algae, bacteria

Cellulose nanofibrils (CNF)

Microfibrillated cellulose, nanofibrils, microfibrils, nanofibrillated cellulose

Bacterial nanocellulose, BNC

Bacterial cellulose, microbial cellulose, biocellulose

Wood, sugar, sugar beet, potato tuber, hemp, flax, delamination of wood pulp, Low molecular weight sugars and alcohols

Average size Diameter: 5–70 nm Length: 100–250 nm (from plant); 100 nm-several micrometer (sourced from tunicates, algae and bacteria) Diameter: 5 to 60 nm Length: Several micrometers

treatment. The process involves the removal of lignin and hemicellulose which are also parts of the plant fiber components. The removal of the lignin and hemicellulose is essential in order to obtain pure cellulose, since both of lignin and hemicellulose are the physical barrier to obtain the cellulose component. Alkali pre-treatment process is usually used since it has some advantages, such as ability to be performed at low temperature and pressure conditions, less sugar degradation, simple in recovery, and elimination of alkali at the end of the pre-treatment process (Kumar et al. 2017). The bleaching process is carried out by applying chlorinated bleaching agents. The bleaching process mainly functions to remove non-degraded lignin and to weaken the intermolecular and intramolecular cellulosic interaction among the cellulose fiber to make it easier to access (Lis et al. 2006). Generally, nanocellulose materials can be classified into three main categories, which are cellulose nanocrystalline (CNC), bacterial nanocellulose (BNC) and cellulose nanofibrils (CNF) (Lin and Dufresne 2014; Mondal 2017). The terms for every type of nanocellulose are summarized in Table 1.2. These types of nanocellulose materials differ in terms of their sizes, physical appearance and production methods. CNC is termed as the cellulose structure that is cultivated under controlled conditions resulting to the creation of high-purity crystalline structure.

1.2.1  Cellulose Nanocrystalline (CNC) Cellulose nanocrystalline (CNC) is widely used in many applications, which generally can be isolated via acid hydrolysis process of cellulosic materials. The sources of CNC are wood pulp (Dong et al. 2016a, b), Ceiba pentandra (Mohamed et al.

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Fig. 1.3  TEM images of CNC from different sorces og cellulosic materials (a) Ceiba pentandra, (b) rice husk, (c) Pandanus tectorius and (d) garlic straw residues. (Adapted from Johar et al. 2012; Kallel et al. 2016; Mohamed et al. 2016a; Sheltami et al. 2012)

2016a), recycled newspapers (Mohamed et  al. 2015, 2016a), soy hulls (Flauzino Neto et al. 2013), Pandanus tectorius (Sheltami et al. 2012), pineapple leaf (Mathew et al. 2010; Santos et al. 2013), garlic straw residue (Kallel et al. 2016), cotton linter (Chang et  al. 2010; Zhang et  al. 2001), sugarcane bagasse (Abdel-Halim 2014; Henrique et al. 2013; Kumar et al. 2014; Li et al. 2012a, b; Maity and Ray 2017; Mandal and Chakrabarty 2011; De Morais et al. 2011) and other biomass. CNC has attractive properties such as large surface area, high tensile strength and stiffness, excellent colloidal stability and can undergo different kinds of modification since it has abundant hydroxyl groups (Grishkewich et al. 2017). CNC has crystalline structure with length less than 500 nm. Chemically, CNC is produced due to the disruption of hydrogen bond, resulting in the cleavage of the amorphous domain of the cellulosic fiber to suit crystalline rod-like structure which refers to CNC structure (Grishkewich et al. 2017). Figure 1.3 shows the images of CNC, fabricated from several types of cellulosic materials, analyzed by using transmission electron microscopy (TEM).

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1.2.2  Cellulose Nanofibrils (CNF) Aside from CNC, there is another type of nanocellulose called cellulose nanorofibrils (CNF). CNF (synonym microfibrillated cellulose, MFC) results from the pack of individual cellulose molecules which have 5  nm of diameter that are brought together to form larger unit, up to 20–50 nm of diameter (Samir et al. 2004a, b; Siró and Plackett 2010). Various kinds of terms have been used to depict CNF including microfibril, microfibril aggregates, nanofiber, nanofibrillar cellulose or microfibrilated cellulose (Adel et al. 2016; Hassan et al. 2015; Minelli and Baschetti 2017; Montplaisir et al. 2017; Zheng et al. 2017). CNF has a web-like structure, with both amorphous and crystalline parts that make it different from CNC, which has crystalline region only (Lu et al. 2008). The production of CNF is believed to source from wood as the cellulosic material. CNF can be modified to form thin films with good strength and inflexibility due to high aspect ratio of fibrils to disperse highly diluted water (Iwatake et  al. 2008; Nogi et al. 2009). The crystal content in CNF and dense structure arrangement via strong interfibrillar hydrogen bonds have good gas barrier properties. The advantages of NFC increase the chances of NFC to be commercialized in related fields, such as nanocomposites and coating formulations to be applied in packaging applications (Fukuzumi et al. 2009; Syverud and Stenius 2009).

1.2.3  Bacteria Nanocellulose (BNC) Bacteria nanocellulose (BNC) can be obtained from the bacteria cellulose of genera Gluconacetobacter, Agrobacterium, Pseudomonas, Rhizobium, and Sarcina. Bacterial cellulose comes in various forms of fibrous network containing no lignin, pectin, hemicelluloses or other biogenic product, and consists of highly pure crystalline up to 84–89% and posseses high degree of polymerization (DP) and high porosity (Czaja et al. 2004; Henriksson and Berglund 2007; Jonas and Farahc 1998; Klemm et al. 2011; Iwamoto et al. 2007; Vandamme et al. 1998). The production of BNC is highly dependent on the culture medium. Low cost culture medium is most preferred due to economically practicable solution to be applied in related fields such as tissue regeneration, drug delivery system and scaffolds for tissue engineering (Barud et al. 2015; Czaja et al. 2007; Czaja et al. 2004).

1.3  Properties of Nanocellulose Nanocellulose is a unique and promising natural material, purified from native cellulose. Cellulose is one of the most abundant renewable polymer with production more than 7.5  ×  1010 tons per year (Habibi et  al. 2010). The main source of the

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Fig. 1.4  The formation of cellulose sourced from tree illustrated in wood hierarchical structure. (Reproduced with the permission from Dufresne 2013)

cellulose is woods which contain up to 50% cellulose (Fig.  1.4). It is the most important composition that can be applied in many applications such as heavy metal removal, water treatment, biomedical, biosensor and bioimaging (Bagheri et  al. 2017; Brinchi et al. 2013; Dufresne 2013). The properties of the nanocellulose can be categorized into three components which are physical properties, surface chemistry and biological properties (Bagheri et al. 2017; Lin and Dufresne 2014). The physical properties of the nanocellulose can be differentiated by the structure, either in ordered or disordered region. Different type of the region has different effect on the characters and properties of the nanocellulose. As mentioned before, the disordered structure of nanocellulose will affect the flexibility and plasticity of the bulk material. Meanwhile, the ordered structure of the nanocellulose will contribute to the stiffness and more elasticity (Lin and Dufresne 2014). Nanocellulose is made up of β-1,4-anhydro-D-glucopyranose units which do not lie specifically in the plane. It is assumed that the chair is conformed with sequential glucose residue that swivels at the angle of 180° (Habibi et al. 2010). The significant property of nanocellulose is the presence of three hydroxyl group in each glucose unit. These hydroxyl group offers a reactive surface since they consist of OH groups which are responsible to form hydrogen bond (Bai et al. 2009; Xiong et al. 2012). The bond formed has a crucial function in the fibrillar formation and semicrystalline packing. The position of the hydroxyl group is believed to have different level of

10

N. A. Awang et al.

reactivity. The hydroxyl group positioned at C-6 is pointed as primary alcohol, whereas hydroxyl group at C-2 and C-3 are labeled as secondary alcohol (Hokkanen et al. 2016a). OH group located at C-6 has the highest reactivity compared with the OH groups present at C-2 and C-3. The reactivity of hydroxyl group at C-6 is 10 times more reactive, while the reactivity of OH group at 2 carbon position is double compared to carbon 3 position (De et al. 2011; Shopsowitz et al. 2011). The carbon atom bonded with the hydroxyl group at C-6 is attached to only one alkyl group, as opposed to carbons located in the hydroxyl group of C-2 and C-3 which are directly attached to alkyl groups, which will bring about the steric effects from the supramolecular structure of the cellulose and reacting agents (Lin and Dufresne 2014). Aside from the reactive group present at the three positions of the nanocellulose, which are C-6, C-2 and C-3, another crucial point of the properties of nanocellulose is the surface charges. The charges come from the negative sulfate esters (-OSO3−). The -OSO3− group is found from CNC during sulfuric acid hydrolysis via condensation esterification (sulfation), from reaction between the surface hydroxyls and H2SO4 molecules (Beck et al. 2011; Hamad and Hu 2010). CNC from acid hydrolysis process possesses highly negatively charge, thus it appears to be well dispersed in water. The surface charge of sulfate groups on nanocellulose can be controlled by controlling the duration and temperature of H2SO4 hydrolysis (Brinchi et al. 2013). Nanocellulose possesses biocompatibility properties. Biocompatibility refers to the ability of the unfamiliar material that is introduced into body to be suited well without causing any lethal changes (Lin and Dufresne 2014). Human body has low level of cellulolytic enzymes, which has effect on the degradation of cellulose, which will contribute to some incompatibility issues (Viljanto et al. 1999). Among three main types of nanocellulose, BNC is the most suitable to be utilized in biomedical field, as it has been proven able to give a better biocompatibility (Andrade et al. 2011; Ferraz et al. 2012; Helenius et al. 2005; Pértile et al. 2012).

1.4  Preparation of Nanocellulose Nanocellulose materials are advantageous as they are harmless, biodegradable, biocompatible, and have higher surface area to volume ration, since they are formed in nano dimension (Mondal 2017; Zhang et  al. 2013). Generally, cellulosic based materials are purified through two main approaches, either by bottom up which is by biosynthesis or top-down by disintegration of plant materials. In top down approach, nanocellulose is chemically induced via destructing strategy of amorphous region to preserve highly pure crystalline structure. The chemical/mechanical destruction processes include acid hydrolysis, enzymatic treatment, high pressure homogenization and grinding. The top down and bottom up approaches for nanocellulose synthesis are summarized in Table 1.3. CNC is produced by chemical treatment, while NCF is obtained via mechanical or treatments process (Moon et al. 2011; Nechyporchuk and Belgacem 2016). In general, the purification of CNC from native cellulose is done via acid hydrolysis

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11

Table 1.3  synthesis approaches of nanocellulose. (Adapted from Bagheri et al. 2017) Synthesis approaches Bottom up biosynthesis

Top down disintegration of plant materials

Feeding materials Fermentation of low molecular weight sugars using bacteria from Acetobacter species

Treated natural fiber with strong ultrasound to break up larger bundle of natural fibers into smaller elementary fibrils while retaining the fibrous texture. Using high pressure homogenizer to reduce the size of wood fiber to nanometers.

Materials • Termed as bacterial cellulose. • Inherently nano-sized ribbon shape cellulose fibrils. • Largest dimension ranging from 25–86 nm. • Length up to several micrometers. • High critical surface energy. • Nanocellulose with organized in extended chain conformation with a high degree of long range order. • Diameter of 5–30 nm, length of 100–500 nm or length of 100 nm to several micrometers. • The morphology and dimension assessed as elongated rod like nanoparticles and each rod could be regarded as a rigid cellulosic crystal without apparent defect.

process. Acid hydrolysis process refers to the removal of the amorphous region, leaving behind the crystalline structure (Santos et al. 2013). According to Peng and co-workers, this method is applied based on the fact that the crystalline locality is acid-insoluble region. Thus, as the cellulosic materials undergo acid hydrolysis process, pure CNC will be obtained as the amorphous region is torn down (Peng et al. 2011). The most common types of acids used for acid hydrolysis process are sulfuric acid and hydrochloric acid (Dufresne 2013). Acid functions to maintain the stabilization of the cellulose nanocrystals which are readily negatively charged, thus it will reduce the tendency to aggregate. As the acid hydrolysis process is in progress, H3O+ ions will penetrate into the cellulose chain located in the amorphous region, which will enhance the hydrolytic cleavage of the glycosidic, and consequently will free out the crystallites (Lin and Dufresne 2014; Silvério et al. 2013). The utilization of phosphoric, hydrobromic and nitric acid has also been reported for the purification of nanocellulose (Espinosa et  al. 2013; Lee et  al. 2009; Liu et  al. 2010; Mascheroni et al. 2016). During acid hydrolysis, some parameters need to be taken into consideration, such as the reaction temperature, duration of the reaction, acid nature, acid concentration, agitation, and the acid-to-cellulose ratio. These parameters will directly affect the morphology and properties of the nanocellulose materials (Kallel et al. 2016). Any free acid molecule resulting from the produced suspension from the acid hydrolysis process is separated by centrifugation and dialysis process (Brinchi et al. 2013; Lavoine et al. 2012). CNF is also obtained via various types of mechanical treatments. The process is carried out based on the type of CNF desired. The most applied mechanical treatments used in fabrication of CNF are homogenizer, microfluidizer and grinder, as

12

N. A. Awang et al.

Fig. 1.5 The mechanical treatment that is normally used in the fabrication of the CNF: (a) Homogenizer, (b) Microfluidizer and (c) Grinder. (Adapted from Lavoine et  al. 2012; Nechyporchuk and Belgacem 2016)

illustrated in Fig. 1.5. The prepared cellulose is maintained in nanometer range by passing over the softwood pulp aqueous suspension through high-pressure homogenizer. In homogenization process, the product temperature is maintained in the range of 70-80 °C by controlling the temperature using cooling water (Lavoine et al. 2012). As the treatment progresses, cluster network of nanofibrils with both crystalline and amorphous regions are yielded due to high shearing force. The dimension of the produced cellulose nanofiber can be varied by altering the processing conditions. The fiber can be cycled from 10 to 20 times through the homogenizer (Andresen et al. 2006). The dimension of CNF starts from 5 nm in size as an individual size and up to 50 nm with the length of few micrometers (Kaushik and Singh 2011; Nechyporchuk and Belgacem 2016). The production of CNF by using homogenizer has attracted interest among researchers since it can be done without undergoing biochemical pretreatment (Dufresne 1999; Nakagaito and Yano 2004). However, homogenizer is not fully commercially used due to high energy utilization which may reach up to 70 MW h/t. Microfluidizer system is recently applied in technology related to the fabrication of macro to micro/nano structure dimension (Aulin et al. 2010). In microfluidization process, suspended cellulose is forced to pass through specific geometry narrow passage in Y-type or Z-type shape that is controlled under high pressure ranging from 150–210 MPa (Kalia et al. 2014; Siqueira et al. 2010). In contrast with homogenizer, microfluidizer can work at a stable shear rate, which can reduce the probability of clogs with consistent size of fibers (Spence et  al. 2011). In addition,

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13

predetermined geometry of the passage used in the microfluidizer guarantees the reproducibility as the samples will proceed for several times (Kalia et al. 2014). BNC is fabricated by two main methods, which are static culture and stirred culture. In static culture, the BNC produced has leather-like structure and thick, compared to BNC fabricated via stirred culture which forms irregular pellet and suspended fiber (Czaja et al. 2004; Krystynowicz et al. 2002). The preparation of BNC by either stirred culture or static culture depends on the final application. As reviewed by Jozala and partners, stirred culture approaches produce low mechanical strength, resulting in lower yields and higher chance of mutation, which will affect the production of BNC (Aytekin and Fikrettin 2014; Jeon et al. 2014; Keshk 2014; Lee et al. 2014).

1.5  Modification of Nanocellulose-Based Materials Cellulose is difficult to disperse in polymer matrix and has poor interfacial adhesion, which has become a concern and one of the challenges in applying cellulosic material in many research fields. Surface modification of cellulose is one of the efforts by researchers in order to minimize these problems. Most of the cellulose will be modified since it consists of numerous hydroxyl groups that make it easily accessible to undergo chemical modification. Numerous approaches related to the modification of nanocellulose have been introduced to suit many applications.

1.5.1  Acid Hydrolysis The first modification of nanocellulose started with the hydrolysis process to produce nanocrystals. Sulfuric acid is a commonly used acid, followed by hydrochloric acid (Habibi et  al. 2010; Moon et  al. 2011). Different types of acid used in acid hydrolysis process have different effect on the produced cellulose nanocrystals. The electrostatic stabilization of the produced cellulose nanocrystals will be improved with the presence of the phosphate or sulfate groups on the surface of the nanocrystals, since these two groups have negative surface charge. In comparison, the utilization of the sulfuric acid is more preferable compared with hydrochloric acid, since it gives higher surface charge density on the purified cellulose nanocrystals (Xuemin 1998; Espinosa et al. 2013). From different finding by Grishkewich, the production of CNC from hydrochloric acid results in low colloidal stability (Grishkewich et  al. 2017). However, in another approach, the combination of acid hydrolysis process by combination of sulfuric acid and hydrochloric acid will create spherical nanoparticles with better thermal stability due to having less sulfate group at the surface (Wang et al. 2007). At low concentration, sulfuric acid will yield NFC (Rebouillat and Pla 2013). However, it is worth to mention that the morphology and the physical properties of

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N. A. Awang et al.

Fig. 1.6  Images of produced CNC sourced from cotton linter fabricated via different concentration of sulfuric acid hydrolysis (a) CNC and (b) TEM image of CNC. (Adapted from Morais et al. 2013)

the produced CNC highly dependent on the acid concentration. In this study, TEM images displayed different morphology of CNC sourced from cotton linter is displayed in Fig. 1.6. Generally, the scission of the glycosidic bond in cellulose via acid hydrolysis process occurs by three main steps: 1. Formation of conjugated acid through the interaction that is created between protons of acid and oxygen of glycoside. 2. Scission of C-O bond and the cleavage of conjugated acid, which turn into cyclic carbonium ions. 3. Release of proton and free sugar after the addition of water. The acid hydrolysis processes by using various kinds of acid from many different types of cellulosic sources in order to fabricate CNC are summarized in Table 1.4. The acid hydrolysis processes by using various kinds of acid from many different types of cellulosic sources in order to fabricate CNC are summarized in Table 1.4.

1.5.2  Oxidation Oxidation is a direct functionalization method by introducing carboxyl group on the surface of nanocellulose materials. The modification will affect the stability, optical, thermo, and dynamic mechanical properties of nanocellulose itself (Abd et al. 2017; Jonoobi et al. 2015; Zhong et al. 2012). 2,2,6,6-Tetramethylpiperidine-1-oxyl oxidation, or universally called as TEMPO oxidation, is the most frequently used pretreatment technique for the modification of the native surface of cellulose (Faradilla

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Table 1.4  Different types of acid hydrolysis in fabrication of CNC Cellulosic sources Rice husk Industrial kelp (Laminaria japonica) waste Laminaria japonica Wood sawdust Oil palm empty fruit bunch pulp Cotton stalk Sugarcane bagasse Raw cotton Kapok fibers Old corrugated container pulp fiber Wheat straw

Pineapple leaf Cotton linter Soy hulls Mengkuang leaves (Pandanus tectorius) Kenaf bast fibers Phormium tenax fibers Bleached softwood Kraft pulp Sisal fibers

Process H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H3PO4 hydrolysis H2SO4 hydrolysis HCl hydrolysis HNO3 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis H2SO4 hydrolysis

References Islam et al. (2017) Liu et al. (2017) Liu et al. (2017) Shaheen and Emam (2017) Azrina et al. (2017) Rahbar et al. (2016) Wulandari (2016) Rahbar et al. (2016) Mohamed et al. (2016b) Tang et al. (2015) Huntley et al. (2015)

Santos et al. (2013) J. P. S. Morais et al. (2013) Flauzino Neto et al. (2013) Sheltami et al. (2012) Kargarzadeh and Ahmad (2012) Fortunati et al. (2012) Beck et al. (2011) Mora (2008)

et al. 2017; Fukuzumi et al. 2009; Jiang and Hsieh 2013; Liu et al. 2016; Ma et al. 2014; Soni et al. 2015). TEMPO oxidation is specifically to attach acidic groups at the C-6 of the glucose unit of cellulose structure (Bagheri et al. 2017; Charreau et al. 2013; Hokkanen et al. 2014a; Hokkanen and Bhatnagar 2016; Jamshaid et al. 2017; Kalia et al. 2014; Spence et al. 2011). TEMPO can be defined as a mild oxidant with supporting co-oxidants, including NaClO or NaBrO which act as primary oxidant that will create the oxidizing systems of TEMPO/NaBr/NaClO and TEMPO/ NaClO/NaClO2. The systems work well at pH 9–11 with the production of sodium carboxylate group (Abd et al. 2017; Fujisawa et al. 2011; Khalil et al. 2014; Eyley et al. 2014). Note that the modification of nanocellulose via TEMPO oxidation does not alter the structural properties of nanocellulose (Habibi et al. 2006). Pre-treatment of TEMPO oxidation normally will be carried out as the first step before the mechanical treatment process. Interestingly, the energy consumed during the mechanical disintegration is more than 100 times lower, with the value of 7 MJ/ kg, compared with the fabrication of nanofibrils which undergoes high pressure homogenizer (700–1400 MK/kg) as pre-treatment method (Missoum et al. 2013). This is due to the fact that the oxidation reaction creates negative charge that generates repulsive force between the microfibrils. The created force indirectly will loosen the cohesion of the microfibrils that is held together by hydrogen bonding. The oxidation tends to swell fibers, and the hydration will make the fibers to be

16

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more flexible, and the accessibility in the crystalline zone will be improved. Therefore, oxidation results in chain scission in amorphous region, which creates defaults within the fiber cell wall to assist the mechanical fibrillation process (Kalia et al. 2014). In short, it is worth to mention that TEMPO oxidation technique is able to reduce energy consumption compared with other methods (Chinga-carrasco et al. 2013; Isogai et al. 2011). Through TEMPO oxidation pre-treatment, nanocellulose sourced from banana pseudo-stem (Musa Balbisiana), labeled as BP, has been successfully fabricated with the diameter of 10–25 nm. The produced nanocellulose is then formed into film that is commercialized as bioplastic especially suited for food. The fabricated nanocellulose derived from BP in translucent film in comparison with the cotton-sourced nanocellulose is shown in Fig. 1.7. The physical appearance of BP which is translucent instead of transparent shows that the film does not only contain nanocellulose but also the presence of substances that adsorb or scatter light (Faradilla et al. 2017).

1.5.3  Esterification and Acetylation The generation of hydrophobic surfaces on nanocellulose can be achieved via several modifications. According to Khalil et  al., the modification can be done via esterification, acetylation, isocyanate, or silylation reaction (Khalil et  al. 2014; Sreekala and Thomas 2003; Taylor et  al. 2012). Principally, esterification can be referred as the process to attach ester functional group –COO on the surface of the cellulose particles. Chemically, the process is based on the condensation of carboxylic acid group -COOH and the alcohol group of –OH (Spinella et al. 2015; Yu et al. 2016a). During hydrolysis process of nanocellulose, sulfonation and phosphorylation are examples of esterification process. The in situ process during the cellulose hydrolysis produces acetylated via Fisher esterification by using a mixture of acetic acid and hydrochloric acid, as presented in Fig. 1.8. The dissociation of hydrochloric acid produces hydronium ions. The produced H+ ions will hydrolyze the amorphous region of cellulose and simultaneously catalyze the esterification reaction onto cellulose chain, especially at hydroxyl groups (Braun and Dorgan 2009; Braun et al. 2013). Aside from esterification, acetylation is another type of hydrophobic modification on the surface of nanocellulose. For this reaction, the surface of nanocellulose

Fig. 1.7  Translucent of BP film (BP refer to banana pseudo-stem). (Adapted from Faradilla et al. 2017)

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17

Fig. 1.8  Illustration reaction of cellulose hydrolysis and esterification simultaneously occurred at the hydroxyl group of cellulose using a mixture of acetic and hydrochloric acid. (Adapted from Braun and Dorgan 2009)

will be introduced with an acethyl functional group of COCH3 (Ifuku et al. 2007; Khalil et al. 2014). The ester group will react with the OH group of cellulose, which results in the plasticization of the cellulosic fibers. The conversion of cellulose into cellulose acetate and cellulose triacetate, with the addition of acetic anhydride, can be accelerated with the addition of the catalyst such as sulfuric acid, perchloric acid, pyridine, potassium, sodium acetate, and gamma-rays. However, the presence of catalyst may create some drawbacks since it will cause the hydrolysis that can destroy the structure of cellulose (Bledzki et  al. 2008; Zafeiropoulos et al. 2002). Cerqueira and co-workers have studied the modification of sugarcane bagasse via acetylation reaction (Cerqueira et al. 2007). In the study, the parameters were manipulated by varying acetic acid concentration, acetic anhydride, sulfuric acid (acting as catalyst), and reaction time. As the outcome, the produced cellulose acetate viscosity-average molecular weight was noted to increase from 5.5 × 103 to 55.5 × 103 g/mol. In other work, acetylation was found able to increase the crystallinity and improve the thermal stability of BNC (Barud et al. 2008). Lin and partners reported that the thermal decomposition temperature of modified NCC via surface acetylation may posses 15 °C higher compared with unmodified NCC. This may be related to the substitution of acetyl group which is more stable compared with hydroxyl group of cellulose. It is worth to cite that the close decomposition temperature between acetylated and native NCC will show that chemical modification does not give a broad effect on the crystalline region of the cellulosic structure (Lin et al. 2011).

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1.6  A  pplication of Nanocellulose-Based Materials for Heavy Metal Removal With the progress of researches, the treatment of wastewater has accomplished a certain level. The presence of heavy metals gives numerous effects towards human being and aquatic lives. Thus, it is important for researchers to find a new alternative to make sure that the existence of heavy metals in wastewater can be minimized effectively. There are many commonly applied heavy metal removal methods such as chemical precipitation, membrane filtration, ion exchange, coagulation, flocculation, electrodialysis, and adsorption (Barakat 2011; Chitpong and Husson 2017; Fu and Wang 2011; Guiza 2017; Gunatilake 2015; Li et al. 2012a; Liu et al. 2016; Lu et al. 2013; Mututuvari and Tran 2014; O’Connell et al. 2008; Omidvar Borna et al. 2016; Saiful and Wessling 2006; Sun et al. 2014; Yu et al. 2003; Yu et al. 2016a, b; Zhao et al. 2016). Chemical precipitation can be categorized into hydroxide precipitation and sulfide precipitation (Zhao et  al. 2016). In this method, heavy metals chemically react with chemicals to form insoluble precipitate that can be separated from the water via separation or sedimentation. The ability for the heavy metals to be removed by chemical precipitation is highly dependent on the pH of the working solution. The removal of heavy metals via chemical precipitation is shown in Fig. 1.9. Although this method is simple and widely used, there are some drawbacks because it requires a large amount of chemicals to reduce the metals. In addition, large quantities of sludge produced at the end of the process require further treatment (Aziz et al. 2008). In membrane filtration, the removal of heavy metals from wastewater can be carried out by considering the size of the particles of the metals. The process can be done by 4 different types of filtration process which are ultrafiltration (UF), reverse osmosis (RO), nanofiltration (NF), and microfiltration (MF). Apart from that, ion exchange process has been cited by many researches as one of the efficient methods for the removal of heavy metals (Ferraz et al. 2012; Gunatilake 2015; Hegazy et al. 2001; Kaith et al. 2015; Kamel et al. 2006; Yu et al. 2016a, b). Ion exchange resin can be classified either as synthetic or natural solid resin (Cavaco et al. 2007). According to many research studies, adsorption technique has a high potential for removal of heavy metals from wastewater (Ali and Saeed 2016; Bailey et al. 1999; Dong et  al. 2016a; Fu and Wang 2011; Guiza 2017; Madivoli et  al. 2016; Mahmoud et  al. 2015; Mittal et  al. 2016; Mututuvari and Tran 2014; O’Connell et al. 2008; Saha and Orvig 2010; Sehaqui and Perez 2014; Shariful et al. 2017; Wojnárovits et al. 2010; Yu et al. 2016a, b). Basically, adsorption refers to the mass transfer process by means of transferring ion particles of heavy metals from liquid phase in wastewater to the surface of the solid by adsorbents. In adsorption process, adsorption isotherm is used to characterize the interaction of the metal ions with the adsorbents. This provides a relationship between the concentration of metal ions in the solution and the amount of metal ions adsorbed to the solid phase when the two phases are at equilibrium (Saha and Orvig 2010). For

1  Nanocellulose-Based Materials for Heavy Metal Removal from Wastewater

19

Fig. 1.9  Chemical precipitation process for heavy metals removal. (Adapted from Barakat 2011)

adsorption isotherms, there are two commonly used models, which are Langmuir and Freundlich models (Gurgel and Gil 2009; Hokkanen et al. 2014b; Khorramfar et al. 2010; Ndi Nsami and Ketcha Mbadcam 2013; Omidvar Borna et al. 2016; Raji and Anirudhan 1998; Stoica-Guzun et al. 2016; Sun et al. 2014; Vijayalakshmi et al. 2016; Yang et al. 2010). Langmuir model indicates monolayer distribution on the surface of cellulose membrane. This model is calculated as shown in Eq. 1.1:



Ce C 1   e qe qm.K qm

(1.1)

where qe (mg of adsorbate per g of adsorbent) is the adsorption density at the equilibrium solute concentration Ce. Ce is the equilibrium concentration of adsorbate in solution (mg/L). Meanwhile, qm (mg of solute adsorbed per of adsorbent) is the maximum adsorption capacity corresponding to complete monolayer coverage, and K is the Langmuir constant (Ndi Nsami and Ketcha Mbadcam 2013). The linear form can be used for linearization of experimental data by plotting Ce /qe against Ce. In order to verify whether the reaction is favorable or unfavorable, dimentionless

20

N. A. Awang et al.

constant separation factor or known as equilibrium parameter, RL is calculated from the equation, as shown in Eq. 1.2:



RL 

1 1  KC0

(1.2)

where RL represents the separation factor (dimensionless), KL is the Langmuir constant and C0 (mg/L) is the initial concentration of the adsorbent. The significance of RL is the value or sign of the adsorption process in the range if: unfavorable (RL > 1), linear (RL = 0), favorable (0 500 samples 6 months

>2000 samples; 10 days 14 days 10 days

0–25,000 ± 6.1 PA – (continued)

3  Conductive Polymer Nanobiosensors

107

Table 3.1 (continued) Company Ultra compact analyzer (Akers Bioscience, Inc.) BIAcore AB SPR instrumentation DEX blood glucose meter

Bioscanner 2000 home blood testing kit and glucose monitor HemoCue B hemoglobin analyzer Elite glucometer KDK lactate analyzer HemoCue GEM Lifescan, UK

Model BIAcore 2000 – Bioscanner 2000

–

Glucometer Elite XL Lactate Pro LT-1710

One Touch Verio IQ One Touch Verio Sync One Touch Ultra Mini One Touch Ping One Touch Ultra 2 Bayer, Canada Contour meter Contour Next meter Contour Next USB meter Contour Next Link meter Contour Next EZ meter Contour USB meter Contour Link meter DIDGET meter BREEZE 2 meter Microlet 2 lancing device Nipro Diagnostics, USA TRUE METRİX TRUE2go

Analyte Biomolecular interactions Glucose

Measuring range (mM) Stability 10–3–10 − 10

–

Glucose, cholesterol, HDL, blood ketone, triglycerides Hemoglobin

Glucose

20–600 mg/dl

–

Lactate

0.8–23

–

Glucose Blood gas Glucose

– – –

– – –

Glucose

–

–

Glucose

–

–

Glucose Glucose Glucose Glucose

– – – –

– – – –

Glucose

–

–

Glucose

–

–

Glucose

–

–

Glucose

–

–

Glucose

–

–

Glucose Glucose Glucose

– – –

– – –

Glucose Glucose

– –

– – (continued)

108

M. Bhattacharjee and D. Bandyopadhyay

Table 3.1 (continued) Company

Prodigy Diabetes Care, Charlotte, NC, USA Nova Diabetes, USA Gediabetes, Taiwan Aga Matrix, USA EPS Bio Technology Corp, Taiwan

American Screening Corp., USA Omnis Health, USA

Simple Diagnostics, USA

Medline, USA Bionime, Taiwan

Advocate, USA

Model TRUEresult TRUEtrack TRUEbalance TRUEread Prodigy AutoCode Prodigy Pocket Prodigy Voice Nova Max Plus Nova Max Link GE 100 Wavesense Presto MDT2 EME EMM EMV2 MasterDriver R13 N Q. STEPS G/C ADMS Embrace meter Embrace Evo Embrace pro Clever choice voice HD Clever choice HD Clever choice mini Clever choice pro EvenCore G3 EvenCore G2 GM 700 GM 720 GM 700S GM 260 GM 550 GM 100 GM 300 Advocate Redi-code + BMB-E 001A

Analyte Glucose Glucose Glucose Glucose Glucose Glucose Glucose Glucose, ketone Glucose Glucose Glucose Glucose Glucose Glucose Glucose Glucose Glucose Glucose, cholesterol Glucose Glucose Glucose Glucose Glucose Glucose Glucose Glucose Glucose Glucose

Glucose

Measuring range (mM) – – – – 20–600 mg/dl 20–600 mg/dl 20–600 mg/dl – – 20–600 mg/dl 50–400 mg/dl 20–630 mg/dl 20–630 mg/dl 20–630 mg/dl 20–630 mg/dl 20–630 mg/dl 20–630 mg/dl 100–400 mg/dl

Stability – – – – – – – – – – – – – – – – – –

– – – 20–600 mg/dl

– – – –

20–600 mg/dl 20–600 mg/dl 20–600 mg/dl 20–600 mg/dl 20–600 mg/dl 100–600 mg/dl 100–600 mg/dl 100–600 mg/dl 100–600 mg/dl 100–600 mg/dl 100–600 mg/dl 100–600 mg/dl –

– – – 96 weeks 96 weeks – – – – – – – –

(continued)

3  Conductive Polymer Nanobiosensors

109

Table 3.1 (continued) Company

Model Advocate Redi-code + BMB-E 001S MHC Medical Products, Easy touch USA ACON, China On call vivid On call chosen On call platinum On call resolve On call advanced-­ dependable & advanced on call E2 II On call Redi-reliable On call plus On call E2 Germaine Laboratories, AimStrip Inc., USA hemoglobin meter AimStrip hemoglobin starter kit 200 AimStrip hemoglobin test combo Syntron Bioresearch, Glucose Inc., USA monitoring system Total cholesterol test ApexBio, Taiwan Eclice Alc GlucoSure AutoCode GlucoSure voice HemoSmart MultiSure GlucoSure star GlucoSure plus UASure The edge

Analyte Glucose

Measuring range (mM) Stability – –

Glucose

20–600 mg/dl

–

Glucose Glucose Glucose Glucose Glucose

– – – – –

– – – – –

Glucose

–

–

Glucose Glucose Hemoglobin

– – –

– – –

Hemoglobin

–

–

Hemoglobin

–

–

Glucose

–

–

Cholesterol

–

–

Hemoglobin Glucose

4–14% 20–600 mg/dl

– –

Glucose 20–600 mg/dl Hemoglobin 4–20 g/dl Glucose, uric acid 30–550 mg/dl, 3–20 mg/dl Glucose 20–600 mg/dl Glucose 30–50 mg/dl Uric acid 3–20 mg/dl Lactate 6–200 mg/dl

– – —, —

– – – (continued)

110

M. Bhattacharjee and D. Bandyopadhyay

Table 3.1 (continued) Company Arkay, Japan

Model Glucocard 01 Glucocard 01 mini Glucocard 01 mini plus Glucometer X-meter GT-1910 Glucocard X-mini Glucocard X-mini plus Glucocard ∑ Glucocard ∑ − mini EKF Diagnostics, USA Lactate Pro-2 LT-1730 Lactate scout STAT-site-MB-HB STAT-site-MHgb Nova Biomedical, USA Stat strip GLU Stat strip GLU/ KET Stat strip LAC Stat strip CREAT Stat strip glucose Xpress Stat strip Xpress GLU/KET Stat strip Xpress LAC Stat strip Xpress CREAT Nova MAX plus Lactate plus Nova max link® Pts Diagnostics, China

CardioChek CardioChek PA CardioChek P

Analyte Glucose Glucose Glucose

Measuring range (mM) 10–600 mg/dl 10–600 mg/dl 10–600 mg/dl

Stability – – –

Glucose

10–600 mg/dl

–

Glucose Glucose

10–600 mg/dl 10–600 mg/dl

–

Glucose Glucose

10–600 mg/dl 10–600 mg/dl

– –

Lactate

0.5–25 mmol/L

–

Lactate Ketone Hemoglobin Glucose Glucose, ketone

0.5–25 mmol/L 0.1–2 mM 4–21 g/dl – —, —

– – – – —, —

Lactate Creatinine Glucose

– – 20–600 mg/dl

– – –

Glucose, ketone

—, —

—, —

Lactate

–

–

Creatinine Glucose, ketone Lactate Glucose Cholesterol Cholesterol Cholesterol

– —, — – – – – –

– —, — – – – – –

3  Conductive Polymer Nanobiosensors

111

3.12  Conclusions Since past few decades, the conducting polymers (CPs) have been employed for the design and development of different electronic devices especially the nanobiosensors. Unlike the conventional polymers, the exceptional electronic, mechanical, and chemical properties of the CPs have attracted the attention of the researchers for their use in different sensing applications. In particular, the exquisite properties of the CPs at the nanoscale have been exploited to develop low-cost and highly sensitive nanobiosensors targeting various applications. This chapter has introduced some of the CPs, which are popular in the field of sensor fabrication. Different nanobiosensors such as bioelectronic-tongue or -nose, aptasensors, immunosensors, H2O2 biosensors, and glucose biosensors have been discussed along with the sensing mechanisms, which are synthesized from diverse CP nanomaterials such as PPy, PANI, and PEDOT, among others. The recent advancements in the nanomaterials research in the field of sensing bring new opportunities to enhance the performance of CP based sensors harnessing the features of nanotechnology. The CP-nanocomposite based sensors have been envisioned to produce sensors having high sensitivity and selectivity. However, the present challenges of CP based sensors are the stability of materials under the ambient conditions and their dependence on the electrical response in different environmental factors. This limits the applicability of the CP based sensor in many realistic sensing conditions. Recent developments have shown a lot of effort in alleviating those limitations with the use of nanoscience and nanotechnology. However, the further scope of improvements is still there to create even better and economic sensing systems. Acknowledgments  We acknowledge the support from Centre for Nanotechnology, Indian Institute of Technology Guwahati for the help and support. We also thank MeitY grant no. 5(9)/2012-NANO, and DST-FIST-grant no. SR/FST/ETII-028/2010, Government of India, for financial aids.

References Adeloju SBO (2007) Electrochemical nanocomposite biosensor system. US Patent US20110042225A1, Ahmad R, Mahmoudi T, Ahn M-S, Hahn Y-B (2018) Recent advances in nanowires-based field-­ effect transistors for biological sensor applications. Biosens Bioelectron 100:312–325. https:// doi.org/10.1016/j.bios.2017.09.024 Ahn SR et  al (2016) Duplex bioelectronic tongue for sensing umami and sweet tastes based on human taste receptor Nanovesicles. ACS Nano 10:7287–7296. https://doi.org/10.1021/ acsnano.6b02547 Akhtar MA, Hayat A, Iqbal N, Marty JL, Nawaz MH (2017) Functionalized graphene oxide–polypyrrole–chitosan (fGO–PPy–CS) modified screen-printed electrodes for non-enzymatic hydrogen peroxide detection. J Nanopart Res 19:334. https://doi.org/10.1007/s11051-­017-­4029-­x Alocilja E, Zhang D (2009) Nanoparticle tracer-based electrochemical dna sensor for detection of pathogens-amplification by a universal nano-tracer (aunt). US Patent US20110171749A1,

112

M. Bhattacharjee and D. Bandyopadhyay

Amouzadeh Tabrizi M, Shamsipur M, Mostafaie A (2016) A high sensitive label-free immunosensor for the determination of human serum IgG using overoxidized polypyrrole decorated with gold nanoparticle modified electrode. Mater Sci Eng C 59:965–969. https://doi.org/10.1016/j. msec.2015.10.093 Anilkumar P, Jayakannan M (2007a) Fluorescent tagged probing agent and structure-directing amphiphilic molecular Design for Polyaniline Nanomaterials via self-assembly process. J Phys Chem C 111:3591–3600. https://doi.org/10.1021/jp066428n Anilkumar P, Jayakannan M (2007b) Single-molecular-system-based selective micellar templates for polyaniline nanomaterials: control of shape, size, solid state ordering, and expanded chain to Coillike conformation. Macromolecules 40:7311–7319. https://doi.org/10.1021/ma071292s Appell D (2002) Wired for success. Nature 419:553. https://doi.org/10.1038/419553a Arya SK, Dey A, Bhansali S (2011) Polyaniline protected gold nanoparticles based mediator and label free electrochemical cortisol biosensor. Biosens Bioelectron 28:166–173. https://doi. org/10.1016/j.bios.2011.07.015 Aydemir N, Malmstrom J, Travas-Sejdic J (2016) Conducting polymer based electrochemical biosensors. Phys Chem Chem Phys 18:8264–8277. https://doi.org/10.1039/c5cp06830d Bahadır EB, Sezgintürk MK (2015) Applications of commercial biosensors in clinical, food, environmental, and biothreat/biowarfare analyses. Anal Biochem 478:107–120. https://doi. org/10.1016/j.ab.2015.03.011 Bajpai AK, Bajpai J, Soni SN (2009) Designing polyaniline (PANI) and polyvinyl alcohol (PVA) based electrically conductive nanocomposites: preparation, characterization and blood compatible study. J Macromol Sci A 46:774–782. https://doi.org/10.1080/10601320903004533 Baker CO, Behrenbruch C, Rahib L (2009) Functionalized polymer biosensor. US Patent US20120088240A1, Baldwin EA, Bai J, Plotto A, Dea S (2011) Electronic noses and tongues: applications for the food and pharmaceutical industries. Sensors 11. https://doi.org/10.3390/s110504744 Bazin I, Tria SA, Hayat A, Marty J-L (2017) New biorecognition molecules in biosensors for the detection of toxins. Biosens Bioelectron 87:285–298. https://doi.org/10.1016/j. bios.2016.06.083 Bhansali S, Vasudev A (2014) Label-free electrochemical biosensor. US Patent US20150247816A1, Bhardwaj N, Kundu SC (2010) Electrospinning: a fascinating fiber fabrication technique. Biotechnol Adv 28:325–347. https://doi.org/10.1016/j.biotechadv.2010.01.004 Bhattacharjee M, Pasumarthi V, Chaudhuri J, Singh AK, Nemade H, Bandyopadhyay D (2016) Self-spinning nanoparticle laden microdroplets for sensing and energy harvesting. Nanoscale 8:6118–6128. https://doi.org/10.1039/c6nr00217j Bhattacharjee M, Nemade H, Bandyopadhyay D (2017) Nano-enabled paper humidity sensor for mobile based point-of-care lung function monitoring. Biosens Bioelectron 94:544–551 Bhondekar AP et al (2010) A novel iTongue for Indian black tea discrimination. Sens Actuat B: Chem 148:601–609. https://doi.org/10.1016/j.snb.2010.05.053 Bogdanović U, Pašti I, Ćirić-Marjanović G, Mitrić M, Ahrenkiel SP, Vodnik V (2015) Interfacial synthesis of gold–polyaniline nanocomposite and its Electrocatalytic application. ACS Appl Mater Interfaces 7:28393–28403. https://doi.org/10.1021/acsami.5b09145 Chaubey A, Gerard M, Singhal R, Singh VS, Malhotra BD (2001) Immobilization of lactate dehydrogenase on electrochemically prepared polypyrrole–polyvinylsulphonate composite films for application to lactate biosensors. Electrochim Act 46:723–729. https://doi.org/10.1016/ S0013-­4686(00)00658-­7 Chen J, Zhang W-D, Ye J-S (2008) Nonenzymatic electrochemical glucose sensor based on MnO2/ MWNTs nanocomposite. Electrochem Commun 10:1268–1271. https://doi.org/10.1016/j. elecom.2008.06.022 Cheng G, Zhao J, Tu Y, He P, Fang Y (2005) A sensitive DNA electrochemical biosensor based on magnetite with a glassy carbon electrode modified by muti-walled carbon nanotubes in polypyrrole. Anal Chim Acta 533:11–16. https://doi.org/10.1016/j.aca.2004.10.044

3  Conductive Polymer Nanobiosensors

113

Choi JW, Han MG, Kim SY, Oh SG, Im SS (2004) Poly(3,4-ethylenedioxythiophene) nanoparticles prepared in aqueous DBSA solutions. Synth Met 141:293–299. https://doi.org/10.1016/ S0379-­6779(03)00419-­3 Coleman MM, Painter PC (1998) Fundamentals of polymer science: An introductory text, 2nd Edn. Taylor & Francis Crispin X et al (2006) The origin of the high conductivity of poly(3,4-ethylenedioxythiophene)− poly(styrenesulfonate) (PEDOT−PSS) plastic electrodes. Chem Mater 18:4354–4360. https:// doi.org/10.1021/cm061032+ Cruz-Silva R, Romero-García J, Angulo-Sánchez JL, Ledezma-Pérez A, Arias-Marín E, Moggio I, Flores-Loyola E (2005) Template-free enzymatic synthesis of electrically conducting polyaniline using soybean peroxidase. Eur Polymer Jour 41:1129–1135. https://doi.org/10.1016/j. eurpolymj.2004.11.012 Czolkos I et al (2016) Prediction of wastewater quality using amperometric bioelectronic tongues. Biosens Bioelectron 75:375–382. https://doi.org/10.1016/j.bios.2015.08.055 Das TK, Prusty S (2012) Review on conducting polymers and their applications. Polymer-Plastics Technol Eng 51:1487–1500. https://doi.org/10.1080/03602559.2012.710697 Deisingh AK, Stone DC, Thompson M (2004) Applications of electronic noses and tongues in food analysis. Int J Food Sci Technol 39:587–604. https://doi.org/10.1111/j.1365-­2621.2004.00821.x del Valle M (2017) Bioelectronic tongues employing electrochemical biosensors. In: Matysik F-M (ed) Trends in Bioelectroanalysis. Springer, Cham, pp  143–202. https://doi. org/10.1007/11663_2016_2 Dutta S, Mandal N, Bandyopadhyay D (2016) Paper-based α-amylase detector for point-of-care diagnostics. Biosens Bioelectron 78:447–453. https://doi.org/10.1016/j.bios.2015.11.075 Fadel TR, Farrell DF, Friedersdorf LE, Griep MH, Hoover MD, Meador MA, Meyyappan M (2016) Toward the responsible development and commercialization of sensor nanotechnologies. ACS Sensors 1:207–216. https://doi.org/10.1021/acssensors.5b00279 Flory PJ (1953) Principles of polymer chemistry. Cornell University Press Gambhir A, Gerard M, Mulchandani AK, Malhotra BD (2001) Coimmobilization of urease and glutamate dehydrogenase in electrochemically prepared polypyrrole-polyvinyl sulfonate films. Appl Biochem Biotechnol 96:249–257. https://doi.org/10.1385/abab:96:1-­3:249 Gerard M, Chaubey A, Malhotra BD (2002) Application of conducting polymers to biosensors. Biosens Bioelectron 17:345–359. https://doi.org/10.1016/S0956-­5663(01)00312-­8 Graham DL, Ferreira HA, Freitas PP (2004) Magnetoresistive-based biosensors and biochips. Trends Biotechnol 22:455–462. https://doi.org/10.1016/j.tibtech.2004.06.006 Gu F, Zhang L, Yin X, Tong L (2008) Polymer single-nanowire optical sensors. Nano Lett 8:2757–2761. https://doi.org/10.1021/nl8012314 Guimard NK, Gomez N, Schmidt CE (2007) Conducting polymers in biomedical engineering. Prog Polymer Sci 32:876–921. https://doi.org/10.1016/j.progpolymsci.2007.05.012 Guo S, Dong S (2009) Biomolecule-nanoparticle hybrids for electrochemical biosensors. TrAC Trend Anal Chem 28:96–109. https://doi.org/10.1016/j.trac.2008.10.014 Ha D et al (2015) Recent achievements in electronic tongue and bioelectronic tongue as taste sensors. Sens Actuat B: Chem 207:1136–1146. https://doi.org/10.1016/j.snb.2014.09.077 Hangarter CM, Bangar M, Mulchandani A, Myung NV (2010) Conducting polymer nanowires for chemiresistive and FET-based bio/chemical sensors. J Mater Chem 20:3131–3140. https://doi. org/10.1039/b915717d Hatfield JV, Neaves P, Hicks PJ, Persaud K, Travers P (1994) Towards an integrated electronic nose using conducting polymer sensors. Sens Actuat B: Chem 18:221–228. https://doi. org/10.1016/0925-­4005(94)87086-­1 Heller A (1999) Implanted electrochemical glucose sensors for the Management of Diabetes. An Rev Biomed Eng 1:153–175. https://doi.org/10.1146/annurev.bioeng.1.1.153 Herrera-Chacon A, González-Calabuig A, Campos I, del Valle M (2018) Bioelectronic tongue using MIP sensors for the resolution of volatile phenolic compounds. Sens Actuat B: Chem 258:665–671. https://doi.org/10.1016/j.snb.2017.11.136

114

M. Bhattacharjee and D. Bandyopadhyay

Holze R, Wu YP (2014) Intrinsically conducting polymers in electrochemical energy technology: trends and progress. Electrochim Act 122:93–107. https://doi.org/10.1016/j. electacta.2013.08.100 Huang K, Wan M (2002) Self-assembled polyaniline nanostructures with Photoisomerization function. Chem Mater 14:3486–3492. https://doi.org/10.1021/cm020206u Huang Y, Mather EL, Bell JL, Madou M (2002) MEMS-based sample preparation for molecular diagnostics. Anal Bioanal Chem 372:49–65. https://doi.org/10.1007/s00216-­001-­1191-­9 Huang J, Virji S, Weiller BH, Kaner RB (2004) Nanostructured polyaniline sensors. Chemistry – A Eur Jour 10:1314–1319. https://doi.org/10.1002/chem.200305211 Huang J, Luo X, Lee I, Hu Y, Cui XT, Yun M (2011) Rapid real-time electrical detection of proteins using single conducting polymer nanowire-based microfluidic aptasensor. Biosens Bioelectron 30:306–309. https://doi.org/10.1016/j.bios.2011.08.016 Jacobs CB, Peairs MJ, Venton BJ (2010) Review: carbon nanotube based electrochemical sensors for biomolecules. Anal Chim Acta 662:105–127. https://doi.org/10.1016/j.aca.2010.01.009 Jang J, Yoon H (2003) Facile fabrication of polypyrrole nanotubes using reverse microemulsion polymerization. Chem Comm:720–721. https://doi.org/10.1039/b211716a Jang JS, Kwon OS, Park SJ (2010) Method for fabricating novel high-performance field-effect transistor biosensor based on conductive polymer nanomaterials functionalized with anti-­ VEGF adapter. US Patent US8138005B2 Jian J, Guo X, Lin L, Cai Q, Cheng J, Li J (2013) Gas-sensing characteristics of dielectrophoretically assembled composite film of oxygen plasma-treated SWCNTs and PEDOT/PSS polymer. Sens Actuat B: Chem 178:279–288. https://doi.org/10.1016/j.snb.2012.12.085 Joshi PP, Merchant SA, Wang Y, Schmidtke DW (2005) Amperometric biosensors based on redox polymer−carbon nanotube−enzyme composites. Anal Chem 77:3183–3188. https://doi. org/10.1021/ac0484169 Kaur G, Adhikari R, Cass P, Bown M, Gunatillake P (2015) Electrically conductive polymers and composites for biomedical applications. RSC Adv 5:37553–37567. https://doi.org/10.1039/ c5ra01851j Kazanskaya N et  al (1996) FET-based sensors with robust photosensitive polymer membranes for detection of ammonium ions and urea. Biosens Bioelectron 11:253–261. https://doi. org/10.1016/0956-­5663(96)88412-­0 Kim BH, Park DH, Joo J, Yu SG, Lee SH (2005) Synthesis, characteristics, and field emission of doped and de-doped polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) nanotubes and nanowires. Synth Met 150:279–284. https://doi.org/10.1016/j.synthmet.2005.02.012 Kim TH, Lee SH, Lee J, Song HS, Oh EH, Park TH, Hong S (2009) Single-carbon-atomic-­ resolution detection of odorant molecules using a human olfactory receptor-based bioelectronic nose. Adv Mater 21:91–94. https://doi.org/10.1002/adma.200801435 Kim J-h, Choi S-w, Lee J-H, Nam GH (2010) Biosensor based on carbon nanotube-electric field effect transistor and method for producing the same. US Patent US20120073992A1 Kim FS, Ren G, Jenekhe SA (2011) One-dimensional nanostructures of π-conjugated molecular systems: assembly, properties, and applications from photovoltaics, sensors, and Nanophotonics to Nanoelectronics. Chem Mater 23:682–732. https://doi.org/10.1021/cm102772x Kim D-M, Moon J-M, Lee W-C, Yoon J-H, Choi CS, Shim Y-B (2017) A potentiometric non-­ enzymatic glucose sensor using a molecularly imprinted layer bonded on a conducting polymer. Biosens Bioelectron 91:276–283. https://doi.org/10.1016/j.bios.2016.12.046 Krantz-Rülcker C, Stenberg M, Winquist F, Lundström I (2001) Electronic tongues for environmental monitoring based on sensor arrays and pattern recognition: a review. Anal Chim Acta 426:217–226. https://doi.org/10.1016/S0003-­2670(00)00873-­4 Kumaran R, Ram MK, Verghese MM, Malhotra BD (1996) Dielectric spectroscopic studies on polypyrrole glucose oxidase films. J Appl Polym Sci 60:2309–2316. https://doi.org/10.1002/ (SICI)1097-­4628(19960627)60:133.0.CO;2-­I Kwon OS et al (2012) Flexible FET-type VEGF Aptasensor based on nitrogen-doped graphene converted from conducting polymer. ACS Nano 6:1486–1493. https://doi.org/10.1021/nn204395n

3  Conductive Polymer Nanobiosensors

115

Langer JJ, Golczak S (2007) Highly carbonized polyaniline micro- and nanotubes. Polymer Degrad Stab 92:330–334. https://doi.org/10.1016/j.polymdegradstab.2006.07.018 Lei J, Cai Z, Martin CR (1992) Effect of reagent concentrations used to synthesize polypyrrole on the chemical characteristics and optical and electronic properties of the resulting polymer. Synth Met 46:53–69. https://doi.org/10.1016/0379-­6779(92)90318-­D Li J, Lee E-C (2015) Carbon nanotube/polymer composite electrodes for flexible, attachable electrochemical DNA sensors. Biosens Bioelectron 71:414–419. https://doi.org/10.1016/j. bios.2015.04.045 Li J, Lin X (2007) Glucose biosensor based on immobilization of glucose oxidase in poly(o-­ aminophenol) film on polypyrrole-Pt nanocomposite modified glassy carbon electrode. Biosens Bioelectron 22:2898–2905. https://doi.org/10.1016/j.bios.2006.12.004 Li H, Dauphin-Ducharme P, Ortega G, Plaxco KW (2017) Calibration-free electrochemical biosensors supporting accurate molecular measurements directly in undiluted whole blood. J Am Chem Soc 139:11207–11213. https://doi.org/10.1021/jacs.7b05412 Liao C, Zhang M, Niu L, Zheng Z, Yan F (2013) Highly selective and sensitive glucose sensors based on organic electrochemical transistors with graphene-modified gate electrodes. J Mater Chem B 1:3820–3829. https://doi.org/10.1039/c3tb20451k Lim CH, Yoo YJ (2000) Synthesis of ortho-directed polyaniline using horseradish peroxidase. Process Biochem 36:233–241. https://doi.org/10.1016/S0032-­9592(00)00193-­X Lin Y-F, Chen C-H, Xie W-J, Yang S-H, Hsu C-S, Lin M-T, Jian W-B (2011) Nano approach investigation of the conduction mechanism in polyaniline nanofibers. ACS Nano 5:1541–1548. https://doi.org/10.1021/nn103525b Liu M, Liu R, Chen W (2013) Graphene wrapped Cu2O nanocubes: non-enzymatic electrochemical sensors for the detection of glucose and hydrogen peroxide with enhanced stability. Biosens Bioelectron 45:206–212. https://doi.org/10.1016/j.bios.2013.02.010 Lu L-M et al (2009) A nano-Ni based ultrasensitive nonenzymatic electrochemical sensor for glucose: enhancing sensitivity through a nanowire array strategy. Biosens Bioelectron 25:218–223. https://doi.org/10.1016/j.bios.2009.06.041 Lu W et al (2017) Adjustable electrical characteristics in hybrid Si/PEDOT:PSS core/shell nanowire hetero-junctions. J Mater Chem C 5:3932–3936. https://doi.org/10.1039/c7tc00376e Luo X, Morrin A, Killard AJ, Smyth MR (2006) Application of nanoparticles in electrochemical sensors and biosensors. Electroanalysis 18:319–326. https://doi.org/10.1002/elan.200503415 Luong JHT, Glennon JD, Gedanken A, Vashist SK (2017) Achievement and assessment of direct electron transfer of glucose oxidase in electrochemical biosensing using carbon nanotubes, graphene, and their nanocomposites. Microchim Acta 184:369–388. https://doi.org/10.1007/ s00604-­016-­2049-­3 Luppa PB, Sokoll LJ, Chan DW (2001) Immunosensors—principles and applications to clinical chemistry. Clinic Chim Act 314:1–26. https://doi.org/10.1016/S0009-­8981(01)00629-­5 Macaya DJ, Nikolou M, Takamatsu S, Mabeck JT, Owens RM, Malliaras GG (2007) Simple glucose sensors with micromolar sensitivity based on organic electrochemical transistors. Sens Actuat B: Chem 123:374–378. https://doi.org/10.1016/j.snb.2006.08.038 Mahmoudiana MR, Aliasa Y, Basiruna WJ, Woia PM, Yousefid R (2014) One-step electrodeposition of Polypyrrole-copper Nano particles for H2O2 detection. J Electrochem Soc 161:H487–H492 Malinauskas A (2001) Chemical deposition of conducting polymers. Polymer 42:3957–3972. https://doi.org/10.1016/S0032-­3861(00)00800-­4 Mallick K, Witcomb MJ, Dinsmore A, Scurrell MS (2005) Polymerization of aniline by auric acid: formation of gold decorated polyaniline nanoballs. Macromolecular Rapid Commun 26:232–235. https://doi.org/10.1002/marc.200400513 Mattoso LHC, Manohar SK, Macdiarmid AG, Epstein AJ (1995) Studies on the chemical syntheses and on the characteristics of polyaniline derivatives. J Polymer Sci Part A: Polymer Chem 33:1227–1234. https://doi.org/10.1002/pola.1995.080330805

116

M. Bhattacharjee and D. Bandyopadhyay

Mazeiko V, Kausaite-Minkstimiene A, Ramanaviciene A, Balevicius Z, Ramanavicius A (2013) Gold nanoparticle and conducting polymer-polyaniline-based nanocomposites for glucose biosensor design. Sens Actuat B: Chem 189:187–193. https://doi.org/10.1016/j.snb.2013.03.140 McCrum NG, Buckley CP, Bucknall CB (1997) Principles of polymer engineering. Oxford University Press, Oxford Mehrzad-Samarin M, Faridbod F, Dezfuli AS, Ganjali MR (2017) A novel metronidazole fluorescent nanosensor based on graphene quantum dots embedded silica molecularly imprinted polymer. Biosens Bioelectron 92:618–623. https://doi.org/10.1016/j.bios.2016.10.047 Musho MK, Noell JO, Tse PH-S (1990a) Use of conductive sensors in diagnostic assays. US Patent US5250439A Musho MK, Noell JO, Tse PH (1990b) Conductive sensors and their use in diagnostic assays. US Patent US5202261A Neoh KG, Pun MY, Kang ET, Tan KL (1995) Polyaniline treated with organic acids: doping characteristics and stability. Synth Met 73:209–215. https://doi.org/10.1016/0379-­6779(95)80018-­2 Niaz PM, Meng WP, Aliasz Y (2016) One-step electrodeposition of Polypyrrole-copper Nano particles for H2O2 detection. J Electrochem Soc 163:B8–B14 Niu Z, Liu J, Lee LA, Bruckman MA, Zhao D, Koley G, Wang Q (2007) Biological templated synthesis of water-soluble conductive polymeric nanowires. Nano Lett 7:3729–3733. https:// doi.org/10.1021/nl072134h Okan M, Sari E, Duman M (2017) Molecularly imprinted polymer based micromechanical cantilever sensor system for the selective determination of ciprofloxacin. Biosens Bioelectron 88:258–264. https://doi.org/10.1016/j.bios.2016.08.047 Papkovsky DB (1993) Luminescent porphyrins as probes for optical (bio)sensors. Sensors Actuators B Chem 11:293–300. https://doi.org/10.1016/0925-­4005(93)85267-­E Park J, Lim JH, Jin HJ, Namgung S, Lee SH, Park TH, Hong S (2012a) A bioelectronic sensor based on canine olfactory nanovesicle-carbon nanotube hybrid structures for the fast assessment of food quality. Analyst 137:3249–3254. https://doi.org/10.1039/c2an16274a Park SJ, Kwon OS, Lee SH, Song HS, Park TH, Jang J (2012b) Ultrasensitive flexible graphene based field-effect transistor (FET)-type bioelectronic nose. Nano Lett 12:5082–5090. https:// doi.org/10.1021/nl301714x Park JW, Park SJ, Kwon OS, Lee C, Jang J (2014) Polypyrrole nanotube embedded reduced graphene oxide transducer for field-effect transistor-type H2O2 biosensor. Anal Chem 86:1822–1828. https://doi.org/10.1021/ac403770x Park C, Lee C, Kwon O (2016) Conducting polymer based Nanobiosensors. Polymers 8:249 Pathak CS, Kapoor R, Singh JP, Singh R (2017) Investigation of the effect of organic solvents on the electrical characteristics of PEDOT:PSS/p-Si heterojunction diodes. Thin Solid Films 622:115–121. https://doi.org/10.1016/j.tsf.2016.12.030 Pumera M, Sánchez S, Ichinose I, Tang J (2007) Electrochemical nanobiosensors. Sens Actuat B: Chem 123:1195–1205. https://doi.org/10.1016/j.snb.2006.11.016 Rajesh AT, Kumar D (2009) Recent progress in the development of nano-structured conducting polymers/nanocomposites for sensor applications. Sens Actuat B: Chem 136:275–286. https:// doi.org/10.1016/j.snb.2008.09.014 Ramanavičius A, Ramanavičienė A, Malinauskas A (2006) Electrochemical sensors based on conducting polymer—polypyrrole. Electrochim Act 51:6025–6037. https://doi.org/10.1016/j. electacta.2005.11.052 Ravi B, Chakraborty S, Bhattacharjee M, Mitra S, Ghosh A, Gooh Pattader PS, Bandyopadhyay D (2016) Pattern-directed ordering of spin-Dewetted liquid crystal micro-or Nanodroplets as pixelated light reflectors and locomotives. ACS Appl Mater Interfaces 9:1066–1076 Rubinstein M, Colby RH (2003) Polymer physics. OUP Oxford Sakač N, Sak-Bosnar M, Horvat M, Madunić-Čačić D, Szechenyi A, Kovacs B (2011) A new potentiometric sensor for the determination of α-amylase activity. Talanta 83:1606–1612. https://doi.org/10.1016/j.talanta.2010.11.053

3  Conductive Polymer Nanobiosensors

117

Sanchez S, Pumera M, Cabruja E, Fabregas E (2007) Carbon nanotube/polysulfone composite screen-printed electrochemical enzyme biosensors. Analyst 132:142–147. https://doi. org/10.1039/b609137g Shinde SD, Jayakannan M (2010) Probing the molecular interactions at the conducting polyaniline nanomaterial surface via a pyrene fluorophore. J Phys Chem C 114:15491–15498. https://doi. org/10.1021/jp106022b Shoji E, Freund MS (2001) Potentiometric sensors based on the inductive effect on the pKa of poly(aniline): a nonenzymatic glucose sensor. J Am Chem Soc 123:3383–3384. https://doi. org/10.1021/ja005906j Shumakovich G, Kurova V, Vasil’eva I, Pankratov D, Otrokhov G, Morozova O, Yaropolov A (2012) Laccase-mediated synthesis of conducting polyaniline. J Molecul Cat B: Enzymatic 77:105–110. https://doi.org/10.1016/j.molcatb.2012.01.023 Skotheim TA, Reynolds J (2007) Handbook of conducting polymers, 2 Volume Set. CRC Press Son M, Lee JY, Ko HJ, Park TH (2017) Bioelectronic nose: an emerging tool for odor standardization. Trend Biotechnol 35:301–307. https://doi.org/10.1016/j.tibtech.2016.12.007 Song S, Wang L, Li J, Fan C, Zhao J (2008) Aptamer-based biosensors. TrAC Trend Anal Chem 27:108–117. https://doi.org/10.1016/j.trac.2007.12.004 Soundarrajan P, Ginsberg V, Yaniv Z (2003) Matrix array nanobiosensor. EP Patent EP1706130A4 Sperling LH (2015) Introduction to physical polymer science. Wiley, Chichester Sun Y, Fang L, Wan Y, Gu Z (2018) Pathogenic detection and phenotype using magnetic nanoparticle-­urease nanosensor. Sens Actuat B: Chem 259:428–432. https://doi.org/10.1016/j. snb.2017.12.095 Tam PD, Hieu NV (2011) Conducting polymer film-based immunosensors using carbon nanotube/ antibodies doped polypyrrole. Appl Surface Sci 257:9817–9824. https://doi.org/10.1016/j. apsusc.2011.06.028 Tao Y, Ju E, Ren J, Qu X (2014) Polypyrrole nanoparticles as promising enzyme mimics for sensitive hydrogen peroxide detection. Chem Comm 50:3030–3032. https://doi.org/10.1039/ c4cc00328d Thakur B, Guo X, Chang J, Kron M, Chen J (2017) Porous carbon and Prussian blue composite: a highly sensitive electrochemical platform for glucose biosensing. Sensing Bio-Sensing Res 14:47–53. https://doi.org/10.1016/j.sbsr.2017.05.002 Thévenot DR, Toth K, Durst RA, Wilson GS (2001) Electrochemical biosensors: recommended definitions and classification1International union of pure and applied chemistry: physical chemistry division, commission I.7 (biophysical chemistry); analytical chemistry division, commission V.5 (electroanalytical chemistry).1. Biosens Bioelectron 16:121–131. https://doi. org/10.1016/S0956-­5663(01)00115-­4 Trevan MD (1988) Enzyme immobilization by covalent bonding. In: Walker JM (ed) New Protein Techniques. Humana Press, Totowa, pp 495–510. https://doi.org/10.1385/0-­89603-­126-­8:495 Urbanova V, Magro M, Gedanken A, Baratella D, Vianello F, Zboril R (2014) Nanocrystalline Iron oxides, composites, and related materials as a platform for electrochemical, magnetic, and chemical biosensors. Chem Mater 26:6653–6673. https://doi.org/10.1021/cm500364x Utracki LA, Jamieson AM (2011) Polymer physics: from suspensions to nanocomposites and beyond. Wiley, Chichester Vinod Kumar K (2008) New-generation nano-engineered biosensors, enabling nanotechnologies and nanomaterials. Sens Rev 28:39–45. https://doi.org/10.1108/02602280810850017 Wallace GG, Smyth M, Zhao H (1999) Conducting electroactive polymer-based biosensors. TrAC Trends Anal Chem 18:245–251. https://doi.org/10.1016/S0165-­9936(98)00113-­7 Wang J (2006) Electrochemical biosensors: towards point-of-care cancer diagnostics. Biosens Bioelectron 21:1887–1892. https://doi.org/10.1016/j.bios.2005.10.027 Wang T et al (2016) A review on graphene-based gas/vapor sensors with unique properties and potential applications. Nano-Micro Letters 8:95–119. https://doi.org/10.1007/s40820-­015-­0073-­1

118

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Weng B, Morrin A, Shepherd R, Crowley K, Killard AJ, Innis PC, Wallace GG (2014) Wholly printed polypyrrole nanoparticle-based biosensors on flexible substrate. J Mater Chem B 2:793–799. https://doi.org/10.1039/c3tb21378a Wu J, Li Q, Fan L, Lan Z, Li P, Lin J, Hao S (2008) High-performance polypyrrole nanoparticles counter electrode for dye-sensitized solar cells. J Power Sources 181:172–176. https://doi. org/10.1016/j.jpowsour.2008.03.029 Wu L, Xiong E, Zhang X, Zhang X, Chen J (2014) Nanomaterials as signal amplification elements in DNA-based electrochemical sensing. Nano Today 9:197–211. https://doi.org/10.1016/j. nantod.2014.04.002 Xia L, Wei Z, Wan M (2010) Conducting polymer nanostructures and their application in biosensors. J Colloid Interface Sci 341:1–11. https://doi.org/10.1016/j.jcis.2009.09.029 Xu S, Liu Y, Wang T, Li J (2011) Positive potential operation of a cathodic Electrogenerated Chemiluminescence Immunosensor based on Luminol and graphene for Cancer biomarker detection. Anal Chem 83:3817–3823. https://doi.org/10.1021/ac200237j Yang K, Xu H, Cheng L, Sun C, Wang J, Liu Z (2012) In vitro and in vivo near-infrared Photothermal therapy of Cancer using Polypyrrole organic nanoparticles. Adv Mater 24:5586–5592. https:// doi.org/10.1002/adma.201202625 Yogeswaran U, Chen SM (2008) Recent trends in the application of carbon nanotubes–polymer composite modified electrodes for biosensors: a review. Anal Lett 41:210–243. https://doi. org/10.1080/00032710701792638 Yoon H, Lee SH, Kwon OS, Song HS, Oh EH, Park TH, Jang J (2009) Polypyrrole nanotubes conjugated with human olfactory receptors: high-performance transducers for FET-type bioelectronic noses. Angew Chem Int Ed 48:2755–2758. https://doi.org/10.1002/anie.200805171 Yue R, Xu J (2012) Poly(3,4-ethylenedioxythiophene) as promising organic thermoelectric materials: a mini-review. Synth Met 162:912–917. https://doi.org/10.1016/j.synthmet.2012.04.005 Zabihi F, Xie Y, Gao S, Eslamian M (2015) Morphology, conductivity, and wetting characteristics of PEDOT:PSS thin films deposited by spin and spray coating. Appl Surface Sci 338:163–177. https://doi.org/10.1016/j.apsusc.2015.02.128 Zha Z, Yue X, Ren Q, Dai Z (2013) Uniform Polypyrrole nanoparticles with high Photothermal conversion efficiency for Photothermal ablation of Cancer cells. Adv Mater 25:777–782. https://doi.org/10.1002/adma.201202211 Zhai D et al (2013) Highly sensitive glucose sensor based on Pt nanoparticle/polyaniline hydrogel Heterostructures. ACS Nano 7:3540–3546. https://doi.org/10.1021/nn400482d Zhang L, Long Y, Chen Z, Wan M (2004) The effect of hydrogen bonding on self-assembled polyaniline nanostructures. Adv Func Mater 14:693–698. https://doi.org/10.1002/adfm.200305020 Zhang G et al (2016) Importance of domain purity in semi-conducting polymer/insulating polymer blends transistors. J Polym Sci B Polym Phys 54:1760–1766. https://doi.org/10.1002/ polb.24080 Zhang R-C et al (2017) Gold nanoparticle-polymer nanocomposites synthesized by room temperature atmospheric pressure plasma and their potential for fuel cell electrocatalytic application. Sci Rep 7:46682. https://doi.org/10.1038/srep46682 Zhou M, Zhai Y, Dong S (2009) Electrochemical sensing and biosensing platform based on chemically reduced graphene oxide. Anal Chem 81:5603–5613. https://doi.org/10.1021/ac900136z Zhou Q, Wang Y, Xiao J, Fan H (2017) Fabrication and characterisation of magnetic graphene oxide incorporated Fe3O4@polyaniline for the removal of bisphenol a, t-octyl-phenol, and α-naphthol from water. Sci Rep 7:11316. https://doi.org/10.1038/s41598-­017-­11831-­8 Zhu Z-T, Mabeck JT, Zhu C, Cady NC, Batt CA, Malliaras GG (2004) A simple poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid) transistor for glucose sensing at neutral pH. Chem Comm:1556–1557. https://doi.org/10.1039/b403327m Zhu C, Yang G, Li H, Du D, Lin Y (2015) Electrochemical sensors and biosensors based on nanomaterials and nanostructures. Anal Chem 87:230–249. https://doi.org/10.1021/ac5039863

Chapter 4

Fabrication and Potential Applications of Nanoporous Membranes for Separation Processes Oluranti Agboola, Patricia Popoola, Rotimi Sadiku, Samuel Eshorame Sanni, Damilola Elizabeth Babatunde, Ayodeji Ayoola, and Olubunmi Grace Abatan

Abstract  Innovative membrane processes are considered a very important segment of controllable separation processes, such as water treatment, gas separation and organic purification. One of the challenges in membrane technology is the challenge of selecting and fabricating membrane material for excellent selectivity and good permeability for selected particle sizes. The utmost operational challenge perturbing the performance of membrane technology is membrane fouling which occur as a result of insoluble materials covering the membrane surface, leading to a reduction in water quality. Other factors perturbing the performance of membrane technology are energy usage and greenhouse emission. Furthermore, the necessity to react to climate change is another major challenge for membrane technology. An excellent membrane should have high stiffness in order to withstand high pressures applied, large surface area and micro- or nanopore structures for excellent selectivity and good permeability for selected particle sizes. The transport of ions and fluid at molecular level, controlled at the nanometer-scale using membranes provide substantial capacity for high selectivity and high fluxes. The potential applications of O. Agboola (*) Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, South Africa Department of Chemical Engineering, Covenant University, Ota, Nigeria e-mail: [email protected] P. Popoola · R. Sadiku Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, South Africa e-mail: [email protected]; [email protected] S. E. Sanni · D. E. Babatunde · A. Ayoola · O. G. Abatan Department of Chemical Engineering, Covenant University, Ota, Nigeria e-mail: [email protected]; damilola.babatunde@covenantuniversity. edu.ng; [email protected]; olubunmi.abatan@covenantuniversity. edu.ng © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_4

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nanoporous membranes are strongly subjected to the chemical and physical properties of a membrane material. The effective pores size, porosity, uniformity, thickness, surface chemistry and morphology also have influence on membrane separation performance. We reviewed the fabrication and potential applications of nanoporous membranes for separation processes, operational challenge, energy usage, greenhouse emission and effect of climate change. Thus, the major points, include: (1) fabrication methods of nanoporous membranes for excellent selectivity and good permeability for selected particle sizes, (2) Theoretical modeling and simulations of nanoporous membranes, (3) potential applications of nanoporous membranes, (4) the recent discovery of novel nanoporous membrane structures aimed at overcoming the challenge of fouling, (5) the challenge of energy usage, (6) addressing climate change as a contributing factor to the challenges of water treatment industry and membrane technology. Keyword  Separation process · Nanoporous membranes · Fabrication methods · Permeability · Solution diffusion model · Molecular mechanisms · Membrane fouling · Energy usage · Greenhouse emission · Climate change

4.1  Introduction Separation process is regarded as a method that converts a mixture of substance into two or more distinct pure mixtures or fractions. Substances in a mixture are physically combined, so processes based on differences in physical properties are used to separate components. Thus, separations vary in physical properties such as size, shape, mass, density. Additionally, separations vary in chemical properties such as chemical affinity between the constituents of a mixture. During separation process, there is usually only physical movement and no substantial chemical modification. If no single difference can be used to accomplish a desired separation, combination of multiple operations will often be performed in order to achieve the desired result. Various membrane materials have been fabricated for different separation processes because different membrane materials offer different characteristics such as wettability, perm-selectivity, chemical resistance, biocompatibility, fouling tendency and are thus, suitable for different applications. There has been good accomplishment in the development of membranes with high flux and good selectivity. However, the energy consumption of some nanoporous membrane, such as nanofiltration membrane is still much higher than the thermos-dynamic limit (Ji et al. 2017). Despite the successful implementation of membrane processes in various industries, continuous development is needed in order to improve the current process efficiency and introduce novel processes for broader applications (Lee 2013). Membrane processes are energy saving method for the separation of mixtures which occur in nearly all production processes in the chemical industry (Jeaze et al.

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2013). However, energy consumption of some membranes is still an issue. The technology of membrane critically plays an important role in energy and environmental infrastructure. The recent advancement of nanotechnology and nanofabrication techniques has resulted in improved membrane phase, offering the opportunities of modifying the membrane structure, morphology or surface properties at the nanoscale (Lee et al. 2011). Membrane technology advancement as led to a new degree of optimising the membrane structure or chemistry for specific applications. For example, the capability of controlling membrane pore size in sub nanometre is extremely necessary for gas separation processes, since the gas molecules are often in Angstrom dimension (Lee 2013). Thus, a new class of material, metal-organic-­ framework with intrinsic Angstrom scale pore size has been tested for gas separation and promising results in term of selectivity and permeability have been achieved (Bae et al. 2010). Nanoporous materials are made up of a regular organic or inorganic framework supporting a regular, porous structure. The size of the pores is generally 100 nano-meters or smaller. Most nanoporous materials can be classified as bulk materials or membranes (Holister et al. 2013). Nanoporous materials have been shown to be useful for many applications including separations, catalysis, and templating. Nanoporous materials come in all varieties with newly developed inorganic metal oxides being a prevalent example (Beck et al. 1992). Presently, artificial nanoporous membranes are highly of interest, mainly because of the applications of artificial nanoporous membranes involving molecular sorting, sensing and separation processes (Liu and Zhao 2004; Ramirez et al. 2008). Some of the most interesting applications of nanoporous membranes come from the ability of nano-pores specific sizes to let some substances pass through the membrane and other not (Holister et al. 2013). As a result of polymeric membrane low-cost fabrication, ease of handling, and excellent performance in terms of selectivity and permeability, polymeric membranes have dominated the market for desalination by RO (Le and Nunes 2016). For any developed membrane technology, transition to commercial success needs both detailed control over device performance and scalability of the membrane synthesis process (Han et  al. 2008a, b). The processes of an effective membrane synthesis should afford a very good control over the average pore diameter and it should produce a narrow distribution for pore diameter (Adiga et al. 2009). In addition, optimum economic is very important for the membrane production process. Thus, membranes with mechanical, chemical and thermal stability are desired for many applications requiring extended functionality in harsh environments (Stroeve and Ileri 2011). In as much as the current membrane technology mainly depend on polymeric materials, the recent discovery of novel nanoporous membrane structures offer new opportunities. Structures such as, porous monatomic layers, nano-sized tubules arrays and self-assembled lamellar thin films have given new opportunities for advances in membrane technology as a result of their enhanced permeability and selectivity. The next sub-sections reviews fabrication methods and the opportunities in membrane technology that aimed in overcoming the challenges of fouling and climate change. Theory and potential applications of nanoporous membrane will also be discussed.

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4.1.1  Porous Monatomic Layers For the porous separation membranes that are suitable for the chemical synthesis process, it is essential to control the pore diameter at the nanoscale according to the size of the product material that is to be separated and to selectively separate only the product material. The components for the porous separation membrane with the potential of fulfilling such functions are organic polymer systems, such as fluorinated polymer, aromatic polyimide and ceramics, such as silica systems and zeolite systems (Iwamoto and Kawamoto 2009a, b). High salt rejection in water desalination or high selectivity for ion separation could be achieved with the use of porous structures and the dimension in the order of one nanometer that is close to the size of water molecules or ions (Gao 2015). Compared to conventional membrane materials such as polymers, the zeolites and porous silica, the graphene oxide membranes with functionalized monoatomic layers as building block is an ideal material for separation processes. The differentiation in the interaction between ions and graphene oxide, its tunable microstructure and physiochemical properties as a result of the rich chemistry of functional groups, allow rational design of selective fluidic transport at the molecular level. Furthermore, exciting prospects are proposed in establishing high performance and low cost clean water technologies (Gao 2015). A mono-layer of graphene is well identified to repel the permeation of small gaseous molecules such as helium, as the electron density of its hexagonal rings will repel the atoms and molecules trying to penetrate through them (Bunch et  al. 2008). Based on this, an atomic layer of pristine graphene could be considered as a perfect gas barrier material. Nanoporous graphene can efficiently select gases, even though graphene is impermeable to gases, due to high surface porosity. Thus, graphene, with monatomic thickness, can potentially surpass the permeability and selectivity limits of conventional membranes and is considered as the ideal membrane material (Xu et al. 2015). The rejection and water flux of dissolved impurities are two main characteristics governing the productivity and separation performance of graphene and graphene oxide-based membranes in water separation processes. When the pore diameter is larger than 0.8 nm, graphene membranes show higher water flux than carbon nanotube membranes due to higher velocity in the centre region (Suk and Aluru 2010). An investigation has shown that graphene nano-pores are able to block salt ions with 2–3 orders of magnitude greater water permeability than commercial reverse osmosis membranes (Pendergast and Hoek 2011). Nevertheless, the helium-­ impermeable graphene oxide membrane allows unimpeded water permeation (Nair et al. 2012). Various mechanisms of water permeation through the layer-by-layer and porous microstructure of the graphene oxide membrane are proposed using molecular dynamics simulations, since unusual molecular behaviour occurs on nanometer-­ length scales. In molecular dynamics simulations, nano-pores with a high number density and predefined sizes can be ideally introduced into a monolayer graphene membrane (Huang et al. 2015). Unfortunately, accurately controlling pore sizes and attaining high pore density on a large-area graphene are technically challenging.

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Nonetheless, extensive efforts have been made to overcome the challenges (Koenig et al. 2012; O’Hern et al. 2014). The rejection of ions and organic dye molecules by graphene and graphene oxide membranes has also been intensively studied (Xu et al. 2015). The selectivity of membrane separation process is primarily attributed to size exclusion and interactions (including chemical and electrostatic ones) with functional groups (Xu et al. 2015). The high rejection for organic dyes is ascribed to size exclusion and electrostatic interaction, and the rejection of ions to Donnan’s exclusion (Han et al. 2013). Graphene oxide membranes demonstrated substantial promise for applications in water purification in various investigations due to their excellent intrinsic mechanical strength (Liu et  al. 2012), high chemical stability (Dreyer et al. 2010), high antibacterial activity (Hu et al. 2010) and exquisite antifouling properties (Dikin et al. 2007). By modifying the pore size and nanochannels through induction and modification of surface oxygen-containing groups, graphene oxide membranes can be oriented towards a narrow pore size distribution, which is more advantageous for accurate sieving based on the size exclusion mechanism (Xu et al. 2015).

4.1.2  Nano-Sized Tubules Arrays Template based synthesis of nanostructured materials is a very common method and can be used to fabricate of nanotubules, nanorods and nanowires of polymers, metals semiconductors and oxides. Different template with nanosized channels have been analysed for the template growth of nanorods and nanotubules (Cao 2004). The two commonly used and commercially available templates are (1) anodized alumina membrane due to the highly controllable pore diameter and cylindrical shape, the optically transparent, chemically stable, bio-inert and a biocompatible material (Poinern et al. 2011) and (2) radiation track-etched polymer membranes due to the geometrically well-defined pores structures and monodisperse pore size distributions (Makkonen-Craigi et al. 2014). The pore sizes and pore densities of radiation track-etched polymer membranes are independently controlled parameters during the production process and can cover a wide range from a few nm to tens of μm and 1–1010 cm−2, respectively (Lalia et al. 2013). Additionally, they are amenable to surface functionalization in order to improve chemical selectivity or permit stimuli-response (He et al. 2009). Track-etched polymer membranes are prepared from polycarbonate (Wanichapicharta et  al. 2000) or polyethylene terephthalate (Sartowska et al. 2013) films with a thickness between 6 and 35 mm. The process involves two main steps: (i) the irradiation with accelerated heavy ions and (ii) a controlled chemical etching of the degraded regions (nuclear tracks). Figure  4.1 shows the fabrication process of track-etched membrane by the track-etching technique. A thin raw polyethylene or polycarbonate film is exposed to high energy ions irradiation to create tracks along their trajectories. Based on polycarbonate track-­ etched membranes, ‘nano-tubule’ membranes with well-defined transmembrane pores having a diameter of a few nanometres had been fabricated (Martin et  al.

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Fig. 4.1  Schematic representation of the fabrication process of track-etched membrane by the track-etching technique. A thin raw polyethylene or polycarbonate film is exposed to high energy ions irradiation to create tracks. Chemical and mechanical stability are the standard for choosing appropriate polymer film that will be sensitive towards ion irradiation and chemically selective etching of ion tracks. (Adapted from Martin et al. 2001)

2001). The preparation was based on controlled deposition of gold layers on the pore walls of the base membranes with pore sizes between ~10 and 30 nm. Through this means, the pore size could step-wise, evenly and reproducibly be reduced. In combination with self-assembled monolayers of functional thiols on the obtained nano-tubules, selective membrane separations could be achieved (Ulbricht 2006). With very narrow pores of less than 2 nm, even the separation of small molecules based on size or shape can be proposed (Lee et al. 2002a, b). There has been great interest in anodic porous alumina, which is fabricated by the anodization of aluminium in an acidic electrolyte. Porous anodic film on aluminum is normally made by anodic oxidation of aluminum substrate in acidic electrolytes, e.g. sulfuric, phosphoric and oxalic solutions. There is a nano-sized pore array arranged quasi periodically in anodized alumina oxide membrane (Zhang et  al. 2003). The centre-to-centre diameter spacing between the pores and length of the pores can be easily controlled by varying the electrochemical parameters (Diggle et al. 1969). Thus, anodized alumina oxide membranes have been used extensively for synthesizing ordered nanometer materials (Xu et al. 2000). In order to fit for the various synthesizing conditions and usage purpose, the thickness and the phase constituent of anodized alumina oxide membrane and the integration of the pore array are important properties (Zhang et al. 2003). For the functional application of anodic porous alumina, the degree of ordering of the hole arrangement is significant in optimizing the performance of the obtained devices (Fan et al. 2005). The naturally occurring self-ordering of holes arranged under appropriate anodizing conditions is one process used in the preparation of anodic porous alumina with an ordered hole arrangement (Masuda et al. 2006). The pre-texturing of aluminum is another process for controlling the hole arrangement of anodic porous alumina (Masuda et al.

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1997). The process depends on the effective preparation of through-hole membranes in naturally occurring ordered anodic porous alumina based on two-layer anodization (Yanagishita and Masuda 2015). In the process, two-layer anodization occur. Firstly, a first anodization in an appropriate electrolyte is required in order to obtain the desired thickness. Secondly, a second anodization in a concentrated H2SO4 electrolyte followed by the detachment of the membrane through the selective etching of the second layer, generates a through-hole membrane very easily. The selective dissolution of the second anodized layer is caused by the high solubility of the oxide layer formed in concentrated H2SO4 (Yanagishita et al. 2017). The resulting material has a distinct geometrical structure, which is made of a closely packed array of columnar cells with central uniformly sized pores. Electroless deposition has been used to finely plate porous membranes with gold, forming gold nanotubes within the pores. A template method has been used to construct gold nanotubules by an electroless plating approach on the surfaces of polymer membrane templates (Nishizawa et  al. 1995). Nanotubules fabricated by a template method are arrays of single dispersive columnar pores. After controlling the gold deposition time, the inside diameter of the nanotubules can be varied down to small molecular dimensions lower than 1 nm. The resulting membranes can be proposed to be useful as molecular sieves (Lee and Martin 2002; Martin et al. 2001). Studies have also shown that this type of gold nanotubules entertains permeation selectivity that is built on the difference in the size of molecules or ions and the electric charge of ions (Lee and Martin 2002; Martin et al. 2001; Kang and Martin 2014). Thus, electroless deposition of thin gold films affords selective control over transport of a range of molecular entities based on their size, charge, and unique chemical properties. Starting from either cylindrical or conical nanopore membranes, simply varying the plating time during electroless deposition enables reproducible fabrication of gold coated nanopores with varying internal diameters, producing pores as small as several nm in optimal cases (Swaminathan et al. 2012). The application of gold nanotubule membranes for molecular separation is principally connected to the properties of the gold such as conductivity, chemical inertness, temperature stability, and the capability to functionalised in order to modify chemical surface properties. The effects of modifiers and the fine structure of molecules on the transport properties of the gold nanotubules prepared by an electroless plating method to deposit gold onto the surfaces of polycarbonate membranes and the walls of pores within membranes have been explored. The gold nanotubules were modified by cysteine or by carbamidine thiocyanate (Huang and Yin 2006). The Study show that the hydrophilicity of modifiers and the planar structure of permeating molecules clearly affect the transport of small organic molecules in gold nanotubules. Tryptophan and vitamin B2 were cleanly separated at pH  6.8. Gold nanotube membranes have also been fabricated, chemically modified and characterized using various porous membranes as a template (Velleman et al. 2008). The researchers controlled the pore size and surface chemistry in order to optimize the transport and selectivity properties. Surface modification of gold nanotube membranes using a highly hydrophobic self-­assembled monolayer of perfluorodecanethiol was applied

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in order to explore the selectivity towards hydrophobic and hydrophilic molecules. Their approach provides control over the pore size of the membrane, with pore sizes being reduced to molecular dimensions. By modifying the membrane with a highly hydrophobic thiol, the separation of hydrophobic and hydrophilic molecules was achieved (Velleman et al. 2008). The fabrication of the nano-array based structured have shown promising advantages of saving time and cost; and they are amenable to surface functionalization in order to improve chemical selectivity or permit stimuli-response.

4.1.3  Self-Assembled Lamellar Thin Films Self-assembly has become an increasing simple useful and inexpensive method for making functional thin film over the past 20 decades. Self-assembly is a common phenomenon with few practical strategies for making ensembles of nanostructures, taking place everywhere in nature and can lead to interesting technological methods, for the bottom-up fabrication of functional nanostructures (Singh et al. 1998). Self-assembly is thus, an essential part of nanotechnology (Whitesides and Grzybowski 2002). Block copolymers are one of self-assembling material that segregates on nanometer length scales, making them ideal for emerging nanotechnologies such as nanoporous membranes (Olson et al. 2007; Phillip et al. 2010). Lots of research have given a basis for understanding block copolymer self-assembly, starting with the characterization of bulk morphologies with the aid of the Flory-Huggins interaction parameter (χ), block volume fractions (ƒ), degree of polymerization (N) and chain architecture, such as linear and star (Bates 1991). In the past one decade, literature has given a working knowledge of surface energy effects in block copolymer thin films; on microstructure orientation and phase transformations (Epps et al. 2007; Han et al. 2008a, b). Nonetheless, a more comprehensive understanding of thin film nanostructures is still a very important research focus (Albert and Epps III 2010), especially, in the aspect of nanoporous membranes for separation processes. The nanoscale self-organization of polymers can be attained by simply joining polymer chains together in a block copolymer. With these outstanding materials, the molecular engineer can combine unique polymers in order to give materials with defined physical properties. Block copolymers constitute a well-studied and well-­ documented set of nanostructured hybrid materials (Hamley 1998). Having the ability to self-assemble into arrays of well-defined nanostructures, block copolymers, can be turned into thin films. Their application as membrane was so far strongly limited by the fact that these thin films have to be transferred manually onto a porous membrane support, or due to the very strict preparation conditions (Li et al. 2010). Even with the well-established great potential of block copolymer based nanostructured materials for membrane separations, two major important challenges still exist. The challenges are direct introduction of ultrathin nanostructured block copolymer films onto porous supports in order to form a thin-film composite membrane,

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and the proof that such membranes can actually achieve good separation (Li et al. 2010). Studies have shown that the performance for thin films containing nanoparticles with the polymeric material revealed the potencies of membrane nanotechnologies in separation processes. Titanium oxide nanoparticle photocatalysis is one of the ultraviolet-based advanced oxidation technologies and nanotechnologies. The technology has gained attention for the development of efficient separation process and purification systems due to the efficiency of titanium oxide in producing highly oxidizing hydroxyl radicals. The oxidizing hydroxyl radicals readily attack and decompose organic contaminants in water. Nitrogen-doped titanium oxide nanoparticles catalysts have shown their effectiveness in the degradation of microbial contaminants in water (Chaturvedi et  al. 2012). Nanostructured titanium oxide films and membranes have the capacity to disinfect microorganisms together with the decomposition of organic pollutants under ultraviolet and visible light irradiation (Choi et al. 2009). Titanium oxide can be integrated in thin films or membrane filters for water filtration as a result of its stability in water (Kwak et  al. 2001). Furthermore, composites of titanium oxide nanoparticles by doping with other metallic nanoparticles have also demonstrated their effectiveness, nonetheless the applications of using titanium oxide nanofibers and thin films need to be investigated for the effective removal of both inorganic and organic compounds (Amin et al. 2014). Thin film nanocomposite membranes comprising of silver and titanium oxide nanoparticles have shown good salt rejection (Lee et al. 2008). The permeability of membrane and salt rejection are seen to be achieved by coatings of titanium oxide and aluminium oxide composite ceramic membranes, coated by iron oxide nanoparticles (Karnik et  al. 2005). Hence, recent the advances of self-assembled lamellar thin films has become progressively useful as a simple and inexpensive method for making functional thin films nanocomposite membranes.

4.1.4  U  nique Fabrication Methods for Nanoporous Membranes Nanoporous membranes are widely used for filtration and separation in desalination processes. They are expected to have high selectivity and be more efficient during separation process. Nonetheless, there are still some restrictions, such as inadequate mechanical strength, broad pore-size distribution, low throughput, high energy consumption and high cost (Tong et al. 2004; Zhang et al. 2008). The use of nanostructured materials for water purification devices has recently been considered (Ma et  al. 2009). Nanostructured materials show numerous advantages such as larger relative surface areas, over conventional micro-structured materials for wastewater purification (Savage and Diallo 2005). Nanoporous inorganic materials offer much higher permeabilities than polymeric materials. Nanoporous inorganic materials also offer high selectivity in many separations of technological interest (Snyder and Tsapatsis 2007; Kim and Nair 2013). Nanoporous materials such as zeolites and

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metal-organic frameworks (MOFs) can be fabricated into selective separation membranes that exploit their molecular- sieving nanopores. Several methods have been established to fabricate nanoporous membranes with controlled pore sizes, for example, making use of nanostructures such as carbon nanotubes in polymer matrices to produce nanoporous membranes. Apart from the pore size control, there has been recent interest in fabricating membranes with high surface pore densities to achieve high transport rates (Acikgoz et al. 2009). Carbon nanotubes can be fabricated through several techniques such as electric-arc discharge, laser ablation and chemical vapor deposition. Carbon nanotubes composites membranes can be fabricated via the incorporation of carbon nanotubes into various membrane materials. With the aid of different types of substrates, carbon nanotubes-based composite membranes can be divided into inorganic and organic polymeric composite membranes. The methods of fabrication carbon nanotubes-based composite membranes comprise of chemical vapor deposition, template method, blending method, in situ polymerization, layer-by-layer self-assembly, direct coating method (Ma et  al. 2017) etc. Some of these methods will be discussed in the following sub-section. 4.1.4.1  F  abrication of Nanoporous Membranes with Photocatalytic Titania Coatings Low pressure driven membrane filtration such as ultrafiltration and microfiltration membrane have been widely used for water treatment owing to their quick and selective separation on removing contaminants. Nonetheless, membrane filtration hardly separates pollutants from water without any further treatment. Such short coming has led to the secondary pollution and membrane fouling. The incorporation of membrane filtration with photocatalysis may be an alternative way to overcome such short coming (Ma et  al. 2010). Investigations on photocatalytic membranes usually use titanium dioxide as photocatalytic layer and they can relatively inhibit the membrane fouling via photocatalytic degradation of the pollutants (Athanasekou et al. 2012; Song et al. 2012). Thus, functionalization of nanoporous membranes with photocatalytic titania coatings has attracted substantial interest over the past one decade (Narayan 2010). The main advantages of this process are (Fu et  al. 1996): (i) a total destruction of organic contaminants, (ii) a complete oxidation of a wide variety of organic pollutants to carbon dioxide, achieved at ambient temperature and atmospheric pressure and (iii) the possibility of using the solar energy as the ultraviolet source (Malato et al. 2000). When irradiated by an ultraviolet light source, such as solar energy, titania is able to degrade organic contaminants and also destroy microorganisms (Danion et  al. 2004). Zhang et  al. (2006) revealed that silica-­titania nanotube composite membranes on porous alumina support membranes removed Direct Black 168 dye by means of membrane separation and photocatalysis. The silica-titania nanotube composite membrane had the multifunction of separation, degradation and improvement of membrane flux in photooxidation of organic contaminants in wastewater (Zhang et  al. 2006). In order to inhibit the recombination of photogenerated charges, Zhao et  al. (2013a, b) designed and

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fabricated a carbon nanotubes-titanium oxide-aluminium oxide composite membrane. Compared with the typical photocatalytic membrane, such as titanium oxide-­ aluminium oxide membranes, the carbon nanotubes-titanium oxidealuminium oxide composite membrane displayed lower photoluminescence intensity and higher photocurrent density, which indicated the higher separation efficiency of its photogenerated charges. In order to get a good combination of membrane flux and rejection, the carbon nanotubes content and the thickness of carbon nanotubes-­titanium oxide layer was optimized. Under the best prepared parameters, the Polyethylene glycol rejection and permeate flux was 70% and 980  L  m−2  h−1, respectively. The optimized carbon nanotubes-titanium oxidealuminium composite membrane under ultraviolet light irradiation exhibited 3 times higher of the stable permeate flux than filtration alone, and the humic acid removal rate of composite membrane was 10% higher than titanium oxidealuminium membranes. Functionalization of nanoporous membranes with photocatalytic titania coatings has attracted considerable attention due to antifouling characteristic via photocatalytic degradation of the pollutants. 4.1.4.2  F  abrication of Nanoporous Membranes Through Chemical Vapour Deposition Chemical vapour deposition is a chemical process used to produce high quality and high performance solid materials. Generally, chemical vapour deposition and template method are commonly used to fabricate inorganic carbon nanotubes-based composite membranes. Chemical vapour deposition is relatively a simple and economical technique for the synthesis of carbon nanotubes as compared to arc-­ discharge, and laser ablation methods. Chemical vapour deposition can be done at low temperature and ambient pressure (Ahmad 2013). The method gives higher purity, larger yield, and better control on the growth parameters and structure. Till today, chemical vapour deposition is considered a cost-effective method for the production of good quality carbon nanotubes. It has the potential to scale up the production of carbon nanotubes to the commercial level (Lee et al. 2002a, b). Chemical vapour deposition methods have already been utilized for template growth of nanostructures in anodic aluminium oxide nanopores (Zhao et  al. 2013a, b). Carbon nanotube-anodic aluminium oxide composites (Reddy et al. 2009) and free-­standing carbon nanotube arrays (Popp et al. 2009) have also been acquired by using chemical vapour deposition growth of carbon nanotubes inside of porous anodic alumina templates. These composite materials have proven to have improved electrical and mechanical properties that make them suitable for sensing, catalysis and battery applications. The synthetic approach for fabrication of carbon nanotubes composite membranes by chemical vapour deposition was reported by some researchers. The method was based on growth of multi walled carbon nanotubes using chemical vapour deposition on the template of nanoporous alumina membranes. Figure 4.2 shows the schematic fabrication method showing the model of nanoporous alumina pore structure and the growth of carbon nanotube structure inside of pores. The

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Fig. 4.2  Schematic representation of the fabrication membrane composite using chemical vapour deposition method. The model of nanoporous alumina pore structure and the growth of carbon nanotube structure inside of pores is shown in the figure. The alumina surface of nanoporous alumina membrane acted as catalyst and generate the growth of carbon nanotube inside of pores. (Adapted from Altalhi et al. 2011)

influence of experimental conditions including different carbon precursor with catalyst and catalyst free, temperature, and deposition time on carbon nanotube growth process was investigated in order to optimise fabrication protocol and quality of fabricated membranes. The problem with overgrowth of carbon nanotube using catalytic decompositions toluene or ferrocene was eliminated by the use catalysis-­ free precursors such as toluene or ethanol showing that alumina surface of nanoporous alumina membrane can act as catalyst and generate the growth of carbon nanotube inside of pores (Altalhi et al. 2011). Chemical vapour deposition method has proven to be a good method of fabricating high quality and high-performance nanoporous membrane. 4.1.4.3  Fabrication of Nanoporous Membranes by In-Situ Polymerization In-situ polymerization means fabrication taking place in the polymerization mixture. In-situ polymerization method involves the polymerization of monomers. The In-situ polymerization method of fabrication involves the dispersion of inorganic nanoparticles in the monomer or monomer solution, and the resulting mixture is polymerized by standard polymerization methods (Kaminsky and Wiemann 2003; Scharlach and Kaminsky 2008). The crucial factor to an in-situ polymerization is the appropriate dispersion of the filler in the monomer. Dispersants may be added in order to help in the de-agglomeration of nanotubes (Geng et al. 2008). Alternately, functionalization (Hong and Kim 2007; Ma et al. 2007) or polymer adsorption (Liu and Chan-Park 2009) methods have been utilized to aid in dispersion. There is

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always the need to use organic modification of the particle surface or the metal precursors in order to improve the wettability with the monomer (Tanahashi 2010). Polymerization is instigated by raising the temperature, adding a chemical that initiates the reaction or by mixing two monomers. Nanotubes are considered microwave absorbing causing an increase in temperature, thus, microwaves have been used to initiate polymerization (Chowdhury et al. 2009). A vertical array carbon nanotubes-­ polyaniline composite membrane prepared by microwave assisted in-situ polymerization was reported by some researchers. With microwave assistance, an enhanced conjugate with a more quinoid structure of polyaniline was found together with the morphology of polyaniline revealing a smaller diameter and denser connection showing a better thermal stability (Ding et  al. 2015). Fabrication of nanoporous membranes by in-situ polymerization has shown to be one promising approach through appropriate dispersion of the filler in the monomer during the polymer composite fabrication. 4.1.4.4  F  abrication of Freestanding Porous Polymer Membranes Using Nanosphere Lithography Nanosphere lithography is a promising inexpensive fabrication tool for making regular and homogenous arrays of nanoparticles with different sizes. The technique combines the advantages of both top-down and bottom-up approaches. Nanosphere lithography has attracted growing interest due to its potential to manufacture a wide range of one-, two-, or three-dimensional nanostructures (Colson et  al. 2013). Assembling colloidal micro-nanoparticles into two dimensional ordered arrangements presents a high potential for applications in different fields. For example, freestanding cross-linked polymer nanoparticle films can be used as filtration membranes to separate small proteins or gold nanoparticles and present the great advantage of a narrow pore size distribution that is never seen in the present polymer membranes (Zhang et al. 2011). A method of fabricating freestanding porous polymer membranes using nanosphere lithography with colloidal silica has been reported. The technique allows the formation of highly ordered membranes with well-defined pore sizes using poly(ferrocenylmethylphenylsilane) as the etch resist (Acikgoz et al. 2009). The adaptability of the method was demonstrated by the fabrication of freestanding polymer membranes, gotten by employing cellulose acetate as a sacrificial layer. The fabrication process starts by spin-coating a sacrificial cellulose acetate layer on a silicon substrate followed by spin-coating of polyethersulfone. This was followed by the assembly of silica nanoparticles by the convective self-assembly method. Detachment of the polyethersulfone membrane from the substrate was achieved by dissolving the sacrificial cellulose acetate layer in acetone. A freestanding polyethersulfone film was obtained, which was used to perform filtration feasibility experiments (Acikgoz et al. 2009).

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4.1.5  T  heoretical Modeling and Simulations of Nanoporous Membranes Membrane permeation is one of the most important features of membrane separation process because membranes with higher permeability have the ability to obtain separation using lower pressure differences and most time with smaller membrane areas. Modeling and simulation of nanoporous membranes could be useful in understanding and predicting the permeation and transport mechanisms of nanoporous membranes. Advances in nanofabrication make it possible to accurately control morphology, pore size, and surface chemistry of nanoporous materials, thus, allowing a good model development for better predictability of mass transport at the molecular level (Li et al. 2011). Solution-diffusion model is a model used in describing the transport in homogeneous polymeric membranes. Firstly, gas molecules are sorbed into the membrane driven by the partition coefficient between the gas and polymer. After that, the sorbed molecules diffuse through the membrane in the direction of the lower pressure side where desorption occurs (Strathmann 2000). Based on the theory of steady-state gas permeation flux of component i, Ni, is a function of pressure difference across membrane, Δp, and membrane thickness, δ, and is defined by Eq. (4.1) (Matteucci et al. 2006; Hosseni and Najari 2016). Ni 



 Pi p (4.1)

where Pi is the permeability coefficient of pure component i and Δp is the pressure difference between the feed and the permeate compartment. For solution diffusion model, it is assumed that pressure inside the polymeric membrane is uniform and that solvent transport is compelled by the chemical potential gradient across the membrane (Santo et al. 2012). Thus, the transport only takes place by diffusion. The constituent that needs to be transported must first dissolve in the membrane. Therefore, a simplified form of solution diffusion model for a solvent mixture, may be given by Eq. (4.2) (Silva et al. 2005).



ji 

Pi , m   V p   wi , f  w i , p exp   Qi   RT   (4.2)

where ji is the volumetric flux of component i, Pi, m is its mass permeability, Qi is its density, wi is its mass fraction in the feed f and in the permeate P, Vi is the partial molar volume, R is the gas constant and T is the temperature. The understanding and ability required for predicting macroscopic transport characteristics for diffusion of interacting molecular species through the complex lattices of nanoporous membranes is key to the ultimate development of traditional applications of technologies. Such application technologies are integrated reaction and separations devices, and more novel ones are, substrates for growth of nanowires and chemical sensors (Snyder et al. 2002). The investigations on molecular modeling to date was aimed at

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understanding the structural dynamics and transport characteristics of perm-­ selective of membrane materials (Ridgwaya et al. 2017). The important of mass transfer in the scientific exploitation of nanoporous materials was recognized from the very beginning of their application in matter upgrading (Kärge and Ruthven 2016). In order to successfully understand a system dynamic, mass transfer in nanoporous materials has thus gained a considerable technological relevance. However, it was only during the past one decade that guest diffusion in nanoporous host materials became accessible to study by direct experimental observation (Bräuer et al. 2006; Kortunov et al. 2007). Direct measurement of diffusion over length scales, typically of micro-meters, was enabled by the development of several microscopic measuring techniques which allow transient concentration profiles or molecular diffusion paths to be followed at this scale (Kärge and Ruthven 2016). The selective transport of membranes is achieved through heterogeneity of mechanisms operation over different length scales. Figure 4.3 shows the length-scale dependence of membrane transport mechanisms with relative scales of gas and water molecules; hydrated ions and gas mean free path (Wang et al. 2017). Dense polymeric membranes; without defined pores, such as reverse osmosis

Fig. 4.3  Membrane characteristics and length scales: Length-scale dependence of membrane transport mechanisms with relative scales of gas and water molecules, hydrated ions and gas mean free path shown on bottom left. Q is the flux; D is the diffusivity; S, is the sorption coefficient; m, is the molecular mass and μ is the viscosity. (Adapted from Wang et al. 2017)

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membranes for water desalination and gas separation membranes are functioned by a solution-diffusion mechanism at the smallest scale (Yampolskii 2012; Ruthven 2009). The solution-diffusion mechanism lead to the selective results from differences in species solubilities and diffusivities in the membrane material. The solubility is governed by the molecular structure, membrane porosity and chemical affinity. The diffusion is influenced by thermally activated rearrangements of the polymer chains that strongly favour size-dependent diffusion of smaller molecules. As a result of the small free volume available, gas transport in membranes with pore diameters just beyond the molecular size depends on diffusion, surface adsorption and condensation of gas molecules in the membrane pores. In pores that are much larger than molecular size but smaller than the gas mean-free path, gas transport depends on Knudsen diffusion. As a result of the transport mechanism, molecules with lower molecular mass travel faster and have higher permeance (Wang et al. 2017). In liquid environments, transport in pores that are larger than molecules or ions is governed by differences in species diffusivity, steric effects, chemical affinity and electrostatic interactions such as; dielectric and surface charge effects (Szymczyk and Fievet 2005). With the existence of a gradient of molecular concentration, the net transport of a molecule due to random motion could be easily presumed to give rise to a flux in the direction of declining concentration. These transport processes are due to Brownian motion of small particles and they are referred to as diffusion. Of course, there are more molecules moving from the region of higher concentration to the region of lower concentration than molecules moving from the region of lower concentration to the region of higher concentration. With this consideration and ignoring the effects of non-linearity, the number of molecules moving towards the lower concentration may be seen to increase in direct proportion with the concentration gradient (Kärge and Ruthven 2016). This is expressed by Fick’s first law of diffusion: j  D



c x (4.3)

This equation relates the molecular flux j with the gradient of concentration c. The factor of proportionality D is referred to as the diffusivity. Combining Fick’s first law with the law of matter conservation using change in concentration with time gives Eq. (4.4). c j  t x (4.4)

Which yields Fick’s second law:

c   c   2 c D  c   c    D   D c 2  t x  x  c  x  (4.5) x 2



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The second equality clearly shows that the diffusivity usually depends on concentration. If the concentration dependence is neglected, Eq. (4.5) reduces to the familiar form of Fick’s second law:



c 2c D 2 t x (4.6)

As a factor of proportionality, the diffusion coefficient D is introduced. In the absence of catalytic conversion, mass conservation is implied, which then leads immediately to Eq. (4.6), describing the change of concentration in time. Equation (4.6) results under the simplifying assumption that the diffusivity does not vary with ∂2c varying concentration. Thus, the change of concentration with time is seen to be 2 proportional to its second spatial derivative ∂x in this case (Tomas 2013). The power in Eq. (4.6) lies on the fact that the distribution of concentrations at any given time can be predicted by knowing the initial concentrations and boundary conditions that defines the diffusing system. Subject to the physical conditions in which experiments are performed, one could specify the diffusion coefficient as DT, the transport diffusivity, or D, the self-diffusivity. The self-diffusivity is applied when systems are in equilibrium, where the concentration gradient in Eq. (4.3) is only artificially introduced through certain labelling of the particles and the overall mass transport is zero. In non-equilibrium systems, the factor of proportionality in the Fick’s equations is the transport diffusivity DT which is determined by the kinetics of the mobile species during the mass transport to reach equilibrium concentration (Tomas 2013). An experimental and theoretical analysis of molecular separations by diffusion through ultrathin nanoporous membranes was investigated. The models predicted the amount of resistance contributed by the membrane by using pore characteristics obtained by direct inspection of porous nanocrystalline silicon (pnc-Si) membranes in transmission electron micrographs. The theoretical results indicated that molecularly thin membranes are expected to enable higher resolution separations at times, before equilibrium can be compared to thicker membranes with the same pore diameters and porosities. Experimental results are found to be in good agreement with the theory. In addition, ultrathin membranes are shown to impart little overall resistance to the diffusion of molecules smaller than the physical pore size cut off. The largest molecules tested experienced more hindrance than expected from simulations, indicating that factors not incorporated in the models, such as molecule shape, electrostatic repulsion, and adsorption to pore walls, are likely important (Snyder et al. 2011). The simulation of the diffusion of calcium ions through a nanopore created in the cell membrane by electroporation, in presence and absence of the external electric field responsible of the membrane permeabilization was also reported by some researchers. A set of coupled differential equations that describe the process of ionic diffusion in a 2-dimentional nanopore model using the AC/DC and Transport of diluted species modules of COMSOL Multiphasic was solved. Furthermore, a simulation of the stochastic molecular dynamics of the calcium ions in the nanopore using Matlab via LiveLink was carried out. The results obtained in

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both simulations were compared and a difference of about one order of magnitude in the values of the ionic flux in the nanopore was found. The qualitative description of the diffusion process evolution was similar in both cases (Gómez et al. 2014). In both cases the transport of ions through the nanopore showed the general characteristics describe in the literature; there is transport of fluids and ions through these nanopores.

4.1.6  Potential Applications of Nanoporous Membranes In order to obtain molecular separation features, the pore structure of nanoporous membranes are very important. With different fabrication methods described above for the generation of ordered nanoporous membranes, the range of potential applications of nanoporous membranes is quite wide. Quite a number of separation applications of membranes containing porous materials have been investigated (Kim and Nair 2013). The following sub-section highlights the applications of nanoporous membranes in water treatment, gas separation, biomedical and biochemical separation, and organics purification. 4.1.6.1  P  otential Application of Nanoporous Membranes in Water Treatment Substantial environmental pollution instigated by global industrialization and population growth has led to a water shortage. This problem has reduced the quality of human life and globally wastes a large amount of money yearly as a result of the related consequences. One main solution for this challenge is water purification. State-of-the-art water purification compels the implementation of novel materials and technologies that are cost and energy efficient (Homaeigohar and Elbahri 2017). The combination of the current developments in nanotechnology with membrane separation are known as some viable and effective approaches to improve membrane performance with their synergistic effects for water and wastewater treatment (Ma et al. 2017; Pendergast et al. 2011). A well-aligned carbon nanotube can function as robust pores in membranes for water desalination applications (Elimelech and Phillip 2011; Das et al. 2014). The hollow structure of carbon nanotube offers frictionless transport of water molecules, hence, makes them appropriate for the development of high fluxing separation techniques (Das et al. 2014). Suitable pore diameters can create energy barriers at the channel entries, rejecting salt ions and thus, allowing water through the nanotube hollows (Sparreboom et  al. 2009). Carbon nanotube pores can also be modified in order to selectively sense and reject ions. Hence, carbon nanotube membranes can be used as a ‘gate keeper’ for size-­ controlled separation of multiple pollutants. Furthermore, it has antifouling, self-­ cleaning and reusable functions. Specifically aligned carbon nanotubes are of special interest for the fabrication of carbon nanotube membranes. The pore

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diameter has exceptional effects on the water passages through the membranes consisting of aligned carbon nanotubes (Das et al. 2014). Fluid flow in carbon nanotubes has attracted an extensive interest due to the frictionless or near frictionless flow in carbon nanotubes (Sparreboom et al. 2009; Whitby and Quirke 2007). The liquid flow through a membrane composed of an array of aligned carbon nanotubes was shown to be faster than it would be predicted from conventional fluid-flow theory by four to five orders of magnitude. This high fluid velocity resulted from an almost frictionless interface at the carbon nanotube wall (Majumder et al. 2005). Due to carbon nanotube excellent chemical inertness, high specific surface area, high mechanical strength and outstanding water-transport property, carbon nanotubes have specifically, received extensive interests in the fabrication of new composite membranes for water treatment application (Corry 2008; Volder et al. 2013; Goh et al. 2013; Lee and Park 2016). The collective outstanding performances of conventional membrane materials with those of carbon nanotubes have made carbon nanotubes-based composite membranes prevalent type of separation membranes for wastewater treatment. Furthermore, carbon nanotubes display promising adsorption, catalytic and electrochemical properties. These properties are useful to couple adsorption, catalytic or electrochemical function with membrane separation process, hence improving water treatment performances of carbon nanotubes-based composite membranes (Ma et al. 2017). Most of carbon nanotubes-based composite membranes are used in water desalination and wastewater treatment. At the moment, carbon nanotubes are extensively been studied. They have attracted substantial consideration as a result of their properties to enhance the efficiency and capability of currently available membrane processes such as nanofiltration (Wang et al. 2015), reverse osmosis (Kim et al. 2014) and membrane distillation (Roy et al. 2014). A unique carbon nanotubes polymer composite membrane was prepared using chemical vapour deposition and a phase inversion method for the treatment of oil-­ containing wastewater. Relative to the baseline polymer, an increase of 119% in the tensile strength, 77% in the Young’s modulus and 258% in the toughness were seen for a concentration of 7.5% carbon nanotubes in the polymer composite. The permeate through the membrane shows oil concentrations below the acceptable 10 mg/L limit with an excellent throughput and oil rejection of over 95% (Maphutha et al. 2013). Hence, an indication of the suitability and good durability of the composite membranes in oil-water treatment (Ma et al. 2017). The design of carbon nanotube based composite material membranes for direct contact membrane distillation was reported by Dumèe et al. (2010). The membranes were characterized and tested in a direct contact membrane distillation setup under different feed temperatures and test conditions. The composite carbon nanotube structures showed significantly improved performance compared to their pure self-­ supporting carbon nanotube counterparts. The best composite carbon nanotube membranes gave permeabilities as high as 3.3 × 10−12 kg/(m × s × Pa) with an average salt rejection of 95% and lifespan of up to 39 h of continuous testing, making them highly promising candidates for direct contact membrane distillation. Over the past two decades, polymeric membranes have taken over the market in drinking water applications; however, ceramic membranes have started attracting increased

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interest in water industry. Though ceramic membranes are considered to be more expensive than polymeric membranes as a result of their low packing density and high manufacturing costs, the cost gap has considerably reduced over time (Liu 2014). Ceramic membranes have been known to have advantageous properties when compared to polymeric membranes. This is due to their unique features such as a higher mechanical stability and a higher chemical stability which leads to longer membrane lifetimes. Additional features are a relatively narrow pore size distribution and higher porosity which leads to better separation characteristics such as higher hydrophilicity resulting in high fluxes at low pressures (Hofs et al. 2011). Ceramic membranes are example of porous inorganic membranes. These membranes are categorised by high permeabilities and low selectivities (Abedini and Nezhadmoghadam 2010). However, ceramic membranes are more prone to breakage than polymeric membranes. The higher mechanical stability of ceramic membranes is obvious from applied high backwash pressures (Meyn et  al. 2008; Shirasaki et  al. 2008). The chemical stability of ceramic membranes is higher than that of polymeric membranes; furthermore, the stability strongly depends on the membrane structure, with finer structures being less stable (Hofs et al. 2011). A new type of a double-layer ceramic membranes was used for the filtration of wastewater. The synthesized membranes were made of a microporous substrate with pore size of about 0.1 l nm. The membranes were prepared following the colloid filtration technique and a thin film functional layer with pore size of about 10 nm according to the sol-gel preparation method. The ceramic membranes were tested for the removal of cadmium, zinc, Methylene Blue and Malachite Green from water under a pressure of 5 bar and a treatment time of 2  h. Liquid filtration and flow tests through these membranes resulted in a rejection rate of 100% for Methylene Blue and Malachite Green (Chougui et al. 2014). Stylianou et al. (2015) presented of novel water treatment systems based on ozonation combined with ceramic membranes for the treatment of refractory organic compounds found in natural water sources such as groundwater. Furthermore, a novel ceramic membrane contactor, bringing into contact the gas phase (ozone) and water phase without the creation of bubbles i.e., bubble-less ozonation, was also presented. Dissolved ozone concentrations of up to 3.8 mg/L were achieved with the use of the ceramic membrane hydrogen peroxide, which resulted in much higher pollutant degradation due to hydroxyl radical’s production. Mineralization increased at higher pH values and O3/H2O2 molar ratio of 0.2 reaching a maximum of around 65% contactor at relatively low flow velocities of around 0.005 m/s. Increased mass transfer coefficients with increasing Reynolds number were observed, leading to the conclusion that membranes with bigger length and smaller inner diameter will show higher efficiency. Microfiltration and ultrafiltration have been used principally for removal of microorganisms and particles from waters owing to their relatively big pores. Microfiltration is very effective in turbidity, the removal of particulate organic matter, bacteria, protozoa and algae. Ultrafiltration can also remove viruses and some organic matter particles (Kabsch-Korbutowicz and Urbanowska 2010). Kaplan-­ Bekaroglu and Gode (2016) investigated the treatment of highly polluted tannery

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wastewater using ceramic microfiltration and ultrafiltration membranes. The impact of membrane pore size and pressure on permeate flux, chemical oxygen demand, and color reduction were examined. All experiments were performed at a lab-scale, using cross-flow ceramic membrane test unit. Three different single-channel tubular ceramic membrane modules (γ-Al2O3, Media, and Process Technology, Inc., USA) with average pore sizes of 10, 50, and 200 nm were used. More than 95% color removal was consistently achieved with ultrafiltration membranes having pore sizes of 10 and 50 nm respectively. Chemical oxygen demand reductions ranged between 58 and 90% at all pressures for ultrafiltration membranes tested in the wastewater. As the test pressure of the ultrafiltration ceramic membranes increased, chemical oxygen demand and color reduction also increased. It was concluded that ceramic ultrafiltration membranes with 10 nm average pore size can be used in removing chemical oxygen demand and color from highly polluted tannery wastewater. The exceptional properties and environmentally friendly nature of graphene has also attracted the interest of researchers owing to its potential applications in wastewater treatment and water desalination (Xu and Zhang 2016). In light of this, graphene nanomaterials, with unique physicochemical properties, are optimum choice. Graphene nanomaterials give extraordinarily high surface area, mechanical durability, atomic thickness, nanosized pores and reactivity toward polar and non-polar water pollutants. These features promulgate high selectivity and water permeability, and thus provide outstanding water purification efficiency. With respect to water separation, graphene possesses an atomic thickness, guaranteeing high fluid permeability (several-fold higher than that of most commercial nanofiltration membranes) and thus energy-cost efficiency (Homaeigohar and Elbahri 2017). Furthermore, there is good capacity for size-selective transport via the nanopores of a highly robust graphene layer or 2-dimensional nanochannels between adjacent stacked graphene sheets. In addition, there are no complications in the fabrication of graphene-­based membranes for desalination (Han et  al. 2013). Graphene can be used for the fabrication of desalination membranes in several forms, such as pristine graphene, graphene oxide and reduced graphene oxide. Pristine graphene is a single 2-dimensional layer of carbon atoms arranged in a hexagonal pattern. Layered oxygenated graphene sheets, that is, those including oxygen functional groups, such as epoxides, carboxyls, hydroxyls and alcohols, on their basal planes and edges, are called graphene oxide (Perreault et al. 2015). Graphene oxide is recently synthesized and fabricated in the forms of papers and films at the industrial-scale. Functional groups and layers separation of graphene oxide membranes can be easily optimized during the process of fabrication in order to achieve best performance for desalination (Huang et al. 2011; Hu and Mi 2013). Dry graphene oxide membranes have layers’ separation of ~5 Å which allows only water vapor molecules to permeate through the membrane. When a graphene oxide membrane is immersed in water, it is swelled, and the layer’s separation is increased to ~10  Å (excluding the thickness of carbon atoms) (Safaei and Tavakoli 2017). With regards to graphene oxide membranes, water molecules permeate through the nanochannels between oxidized regions (which is within pristine regions) given by the hydrophobicity of functional groups. Particles that have a smaller size than the

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graphene oxide nanochannels could permeate in the membrane with the speed of orders of magnitude greater than conventional membranes (Abraham et al. 2017; Zhang et al. 2017). Boukhvalov et al. (2013), on the basis of first principles calculations established models for hybrid systems composed of water and graphene oxides. The study indicated anomalous water permeation to low friction between the water monolayer and pristine graphene regions. The study showed that the formation of hexagonal ice bilayer in between the flakes and melting transition of ice at the edge of the flakes are crucial in order to realize the perfect water permeation across the whole stacked structures. The distance between adjacent layers that can be controlled either by oxygen reduction process or pressure was shown to determine water flow, hence highlighting a unique water dynamic in randomly connected 2-dimensional capillaries (Nair et al. 2012). Potential Application of Nanoporous Membranes in Organics Purification The contamination of underground layer of water-bearing permeable rock by toxic organic compounds is a widespread problem that prevents the potentially potable sources from being used for drinking water. Trichloroethylene and 2,4,6-­trichlorophenol, a carcinogenic and persistent pollutant, denote the large class of chlorinated organics responsible for the contamination of many potential drinking water sources around the world (Lewisa et al. 2011). Current advances in membrane technology have resulted to an increased use of synthetic membranes for the treatment of water including the removal of viruses and unwanted chemicals from contaminated sources of water (Shannon et al. 2008). 4.1.6.2  P  otential Application of Nanoporous Membranes in Gas Separation Natural gas is considered one of the most vital energy sources, containing high calorific value, high efficiency and low pollution. Raw natural gas comprises of diverse components that are significantly differs in composition from source to source. Natural gas contains methane (typically 75–90% of the total) and other hydrocarbons, such as, butane, ethane and propane. Furthermore, the gas contains some undesirable impurities, such as water, carbon dioxide, nitrogen and hydrogen sulfide. For the safety in moving natural gas, the composition of natural gas delivered to the commercial pipeline grids is tightly controlled (Sun et al. 2015a, b). Hence, a natural gas processing must be conducted before it enters the pipelines, which mainly involves the gas separation processes such as membrane separation. However, permeability is one of the most important features of gas separation membranes because membranes with higher permeability can achieve separation using lower pressure differences and smaller membrane areas (Sun et al. 2014). Two-dimensional carbon, graphene, having a single-atom-thick sheet of sp2-­ hybridized carbon atoms arrayed in a honeycomb pattern, has broaden new

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innovative ideas for researchers to prepare the next generation of membranes with exceptional separation capacities (Huang et al. 2014). Nonetheless, pure graphene sheets are impermeable to gases owing to the high electron density of the aromatic rings that repel any atoms or molecules that try to pass through the graphitic plane (Russo et al. 2013). The presence of holes within the graphene plane is required in order to achieve the gas permeability (Jiang et al. 2009). Thus, porous graphene has been widely studied for its use as membrane for gas separation (Du et  al. 2011; Hauser and Schwerdtfeger 2012). In addition, scientists suggested that nanoporous graphene, a graphene sheet containing pores of size sub-nanometers, with monatomic layers, high mechanical strength and strong chemical stability, could have a great potential for a very promising size-selective nature-biogas separation (Sun et al. 2015a, b; Liu et al. 2013). The prospect of nanoporous graphene is due to one-­ atomic thickness and the molecular sieving effects. Due to the one-atom thickness of graphene, the transport rates of molecules through the nanoporous graphene membranes are anticipated to be exceedingly high (Sun et al. 2015a, b). Besides, another graphene-related material, graphene oxide, was identified as potential filtration membrane material (Xu and Zhang 2016). Graphene oxide is an analogue of graphene when asymmetrically modified with oxygen-containing functional groups such as epoxy groups, carboxyl, carbonyl, hydroxyl, phenol, etc., on the edges and planes. The separation of hybrid molecules via graphene oxide membranes is achieved by the selective molecular diffusion in the interlayer spacing between the oxygen-containing groups on the graphene sheets and the structural defects within graphene oxide flakes. The merits of graphene oxide membranes include ease of synthesis, controllable pore distribution, ease of scale-up and ease of reassembled into large-area film; but at the cost of permeance is much smaller than those predicted for the single-layer nanoporous graphene membranes. Thus, nanoporous graphene membranes overcome the limitation of membranes, and its permeance can attain the maximum performance, theoretical, deserving the attentions from researchers (Sun et al. 2015a, b). Jiang et al. (2009) proposed that the nanoporous graphene with specific pore size and geometry would be a very efficient gas separation membrane using first principle calculations. It was found that a high selectivity on the order of 108 through an N-functionalized pore and an extremely high selectivity on the order of 1023 through an all-H passivated pore for separating H2/CH4 mixtures with a high hydrogen gas permeance were achieved. Du et al. (2011) fabricated a series of nanoporous graphene for separating nitrogen gas and hydrogen gas and found that there were different mechanisms for nitrogen gas and hydrogen gas to permeate through the nanoporous graphene membrane. The hydrogen flux was linear with respect to the pore size of nanoporous graphene, while nitrogen flux was not. This shows that the mechanisms of hydrogen and nitrogen permeation through the porous graphene are totally different. As a result of the difficulties in experimental works, Koenig et al. (2012) employed a pressurized blister test and mechanical resonance to measure the transport rates of a variety of gases (H2, CO2, Ar, N2, CH4, and SF6) through the graphene nanopores, formed by ultraviolet-induced oxidative etching. Though, their measurement just involved the micrometer-sized graphene membrane, which was

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far from the industrial scale. Celebi et al. (2014) however, presented a high transport rate for numerous gases across physically perforated double-layer graphene containing pores with narrowly distributed diameters. The area of the membrane they fabricated was up to square millimetres. It was shown from their work, that the industrial scale nanoporous graphene-based gas separation membrane is attainable. Hence, the investigations reviewed in this section showed that nano-sized pores can be produced during the fabrication of functional gas membranes using graphene for effective gas separation. 4.1.6.3  P  otential Application of Nanoporous Membranes in Biomedical and Biochemical Separation The incorporation of nanoporous membranes into microfluidic devices permits a wide range of analytical biomedical and biochemical applications such as stable concentration gradient generation, biomolecule detection, drug delivery, sample pre-concentration, ion and biomolecule filtration in a controllable manner (Kim and Kim 2013). Figure 4.4 shows nanoporous membranes in biomedical and biochemical applications. These applications are now being recognised with nanoscale pore structures that can offer high selectivity established on specific molecular

Fig. 4.4  Nanoporous membranes for biomedical and biochemical applications. Nanoporous membranes have several potential biomedical and biochemical applications that involve cell growth and tissue engineering, isolating and releasing of biological molecules, smart implantation of drug delivery and Haemodialysis, DNA sequencing and protein separation

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characteristics. Thus, molecular transport controlled at the nanometer-scale by means of membranes offers great potential for high selectivity and high fluxes (Stroeve and Ileri 2011). Nonetheless, a complicated biological system such as a biochemical pathway can only be understood once each one of its constituents has been separately selected and analysed. Hence, a vital element for high selectivity is strengthened by the interactions molecule-pore in nanopores. Therefore, it is essential to understand the effects of pore size and shape, pore surface modification, and probably the osmotic flow and electric field variability within nanopores. All these parameters control the flux of bio-macromolecules through nanopores (Stroeve and Ileri 2011). There are numerous examples of nanoporous membranes performing multiple functions in a controllable manner for biological systems. For example, curving biological membranes have established the complex architecture of the cell and mediates membrane traffic to control flux through subcellular compartments. The molecular mechanisms of membrane curvature rarely react alone, but instead cooperate in diverse ways in order to achieve the highly complex and well-regulated membrane architectures needed by cells (Jarsch et al. 2016). Since biological reactions reduce the capability of active medical devices to interact with the biological environment, the challenge in biomaterials engineering is the invention of materials that will reduce cell adhesion, protein deposits, and encapsulation. Biosensors and drug delivery implants are active medical devices that must be capable of functioning during use over the months, years, and probably decades. These devices must evince functional stability in an extensive range of biological conditions. The functional lifetime of an active medical device will be dramatically increased if biofouling (especially protein absorption) and inflammation are reduced (Adiga et al. 2009). Nonetheless, the development of smart nanoporous membranes have becomes critical for a variety of implantable medical devices, including controlled and signal responsive drug delivery (Adiga et  al. 2009). Controlled delivery systems are designed to release definite amounts of therapeutic agents to a specific site over prolonged duration time and with a definite kinetics. The benefits of controlled release are greater drug effectiveness, better balanced drug concentrations in the body, administration of drugs in a chosen way for more effective therapy and more convenience to the patient. In biomedical application, a membrane is used to moderate the rate of delivery of drug to the body in controlled drug delivery systems. The membrane controls permeation of the drug in some devices, from a reservoir in order to achieve the drug delivery necessary rate. Some other devices employ the osmotic pressure built by diffusion of water across a membrane to power miniature pumps. And for other devices, the drug is impregnated into the membrane material, this slowly dissolves or degrades in the body. Hence, drug delivery is then controlled by the combination of diffusion and biodegradation. By tailoring the properties of the membrane at the molecular level, an effectively materials that possess specific kinetics release can be designed. The kinetics can be designed in order to make available a sustained release of drug delivery in the desired application of the membrane (Peinemann and Nunes 2008; Li et al. 2012).

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The current types of membrane-based controlled drug delivery systems are osmotically controlled, diffusion controlled, swelling-controlled and chemically controlled systems (Peinemann et  al. 2008). The osmotic-controlled release oral delivery system is an advanced drug delivery system that uses osmotic pressure as the driving force to transport pharmacotherapy, usually once-daily, in several therapeutic areas. The key clinical advantages of osmotic-controlled release oral delivery system are their ability to improve treatment tolerability and patient compliance. These benefits are primarily driven by the ability to deliver drugs in a sustained manner, independent of the drug chemical properties of the patient’s physiological factors or concomitant food intake. Osmotic drug-delivery systems appropriate for oral administration is usually made up of a compressed tablet core that is coated with a semipermeable membrane coating. The coating has one or more laser drilled holes in it, through which a solution or suspension of the drug is released over time. The level at which the core absorbs water depends on the osmotic pressure generated by the core components and the permeability of the membrane coating (Ahuja et al. 2012). Rajeshri and Bajaj (2010) designed an oral monolithic osmotic system for highly water-soluble pramipexole dihydrochloride monohydrate. The designed monolithic osmotic system was fabricated using controlled porosity membrane, the system delivers drug in controlled manner for lengthy period of time. Controlled porosity osmotic membrane consists of cellulose acetate as coating polymer and water-soluble pore formers, which forms an in-situ microporous membrane after imbibing water, thus no laser drilling is required. Pore formation was controlled by varying concentration of pore forming agents to get controlled release of pramipexole for period of 24 h. Diffusion plays a key role in most controlled drug delivery systems. The overall release rate is often affected by several physical and chemical phenomena, such as, a combination of water diffusion, drug dissolution, drug diffusion, polymer swelling, polymer dissolution, and-or polymer degradation (Siepmann et  al. 2012). In diffusion-controlled membrane systems, the drug release is controlled by transport of the drug across a membrane (Li et al. 2012). According to Fick’s law, the transport depends on the drug diffusivity through the membrane and the thickness of the membrane (Baker 2004). These systems find extensive application in pills, implants and patches. The Fick’s First Law relates diffusion flux, J (mass flow per unit area) to the gradient in solute concentration, c, (see Eq. 4.3). The diffusion equation can be solved when initial and boundary conditions are specified. The initial condition refers to the initial drug distribution in the system, before the release process commences. Boundary conditions refer to the conditions at the drug delivery system’s boundaries during drug release; these specify drug concentrations or concentration gradients at the device’s surfaces (Siepmann et al. 2012). Diffusion drug delivery systems are either reservoir or matrix-based diffusion systems. In reservoir systems, the drug solution is encapsulated within a polymer droplet, forming a permeable barrier between the surrounding environment and the drug solution environment (Stevenson et al. 2012). As the reservoir is made of a permeable polymer barrier coating, the influence of swelling is seen as a

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non-uniform volume expansion where the barrier coating permits water permeability and swells. However, the internal components can diffuse out of the system. In order for effective diffusion of drug molecules to occur, the pore size of the swelled barrier must greatly surpass the size of the hydrophilic drug molecule or hydrophobic drug particle (Holowka and Bhatia 2014). In matrix-based systems, the drug is blended with a polymer to produce a composite matrix where water permeation leads to either swelling or osmotically controlled systems (Siepmann et al. 1999). As the matrix is made of both drug and polymer molecules, the influence of swelling is seen as a uniform volume expansion of the bulk polymeric material, allowing the opening of pores throughout the matrix structure. This is conceptually not like a sponge that uniformly swells with water. In order for functional diffusion of drug molecules to occur, the pore size of the swelled matrix must significantly surpass the size of the hydrophilic drug molecule or hydrophobic drug particle (Holowka and Bhatia 2014). Simon (2011) analysed the dynamic performances of two different controlled-­ release systems. In a reservoir-type drug-delivery patch, the transdermal flux was affected by the properties of the membrane. A constant thermodynamic drug activity was preserved in the donor compartment. Monolithic matrices are among the most inexpensive systems used to direct drug delivery. In these structures, the active pharmaceutical ingredients are encapsulated within a polymeric material. Despite the popularity of these two devices, to tailor the properties of the polymer and additives to specific transient behaviours, can be challenging and time-consuming. Hence, a method to calculate the flux response time in a system consisting of a reservoir and a polymeric membrane was proposed and confirmed. Nearly 8.60 h passed before the metoprolol delivery rate reached ninety-eight percent of its final value. Ninety-eight percent of alpha-tocopherol acetate was released in 461.4 h following application to the skin. The effective time constant can be computed to help develop optimum design strategies.

4.2  Membrane Fouling Membrane fouling is an on-going challenge in membrane desalination processes. Even drinking water sources contain low ppm levels of natural organic matter, which is a complex foulant (Fane 2011). With regards to fouling and cost factors, ultrafiltration membranes and microfiltration membranes are technically popular than nanofiltration membranes (Le-Clech et al. 2006; Sombatsompop 2007). Both ceramic and polymer materials can be used to make ultrafiltration and microfiltration membranes (Le and Nunes 2016). Ultrafiltration processes separate large and small solutes by forcing colloidal solutions through a nanoporous membrane sieve (Winans et  al. 2016). Protein and natural organic matter fouling problem is presumed to be one of the main shortcomings of nano-porous membrane applications. Though the desire to achieve the optimum throughput of membrane needs high

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fluxes which have the tendency of accelerating fouling. Hence, low fouling membranes are the saving grace, but feed pre-treatment is expected to remain a crucial and challenging aspect of membranes and water treatment (Fane 2011). Usually, lower fluxes result in a reduced amount of fouling, as the alleviated effects of stirring or tangential flow have lesser concentration build-up during filtration (Winans et al. 2016).

4.2.1  Mitigation of Nanoporous Membrane Fouling Generally, membrane fouling is caused by a combination of different foulants. The characterization of membrane fouling can be divided into destructive (membrane autopsy) and non-destructive methods. Each class of membrane fouling characterization methods has its pros and cons in recognising the root cause of the fouling. Membrane autopsy method is widely used to study the origin, extent of membrane fouling and distribution of foulants because it can offer exact information about foulants compositions and properties (Goh et  al. 2018). However, membrane autopsy method is a destructive method. Non-destructive methods such as pressure drop as a function of operation time and observation of flux profile could be carried out continuously during the operation. Nonetheless, these methods do not offer an in-depth information on the changes of the membrane surface properties. However, destructive methods can recognise specific foulants on the surface of the membrane but need the membrane element to be sacrificed. Hence, these methods are suggested to be performed at laboratory scale prior to the large-scale membrane process implementation (Goh et al. 2018). The performance of a nanoporous membrane is usually restricted by fouling, which can occur either through physical pore interactions with the colloids or from a loss of permeability as colloids back up behind the filter (Winans et al. 2016). The choice of appropriate anti-fouling modifiers integrated in the nanoporous membrane matrix can also serve as a good fouling resistance to the interior of the nanopore walls. Anti-fouling surface modifiers are surface grafting and surface coating of thin films; the representation of the two modifications are shown in Fig. 4.5. In addition to the modifications of membranes, the pre-­ treatment of feed water is also a promising strategy used in minimizing membrane fouling through the removal of foulants and their precursors such as transparent exopolymer particles (Prihasto et al. 2009). Adjustment of water chemical can further be done during the pre-treatment of feed water (Goh et al. 2018). Hence, the construction of multi-functional membranes with high innovation and potential is of great interest, as the production of membranes with separation, catalytic, degradation, anti-fouling, antibacterial properties will be achieved (Wang et al. 2018).

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Fig. 4.5  Representation of membrane surface modification to improve antifouling properties. (a) Coating of a thin nonporous dense film; and (b) grafting of polymer chains on top of membranes. Coating of a thin nonporous dense film is achieved by constructing various hydrophilic layers onto membrane surfaces. In surface grafting method, hydrophilic polymer chains are immobilized onto the surface of the membrane in order to provide a fouling resistance layer. (Adapted from Shahkaramipour et al. 2017)

4.2.1.1  Surface Coating Method In this method, various hydrophilic layers are constructed by spraying steps or by dipping or by directly adsorbing water-soluble polymers or amphiphiles onto membrane surfaces (Zhu et al. 2014). The materials for coating do not have any attraction towards the foulants such as proteins, emulsion and organic compounds; thus, avoiding any favourable interactions between the foulants and membranes. The surface coating with a nonporous dense layer would also block the foulants from transporting through the skin layer, hence, avoid internal fouling (Shahkaramipour et al. 2017). Various studies have modified nanoporous membranes using coating method. Yang et al. (2017) produced antifouling ultrafiltration composite membranes with mesoporous films of polystyrene and polyethylene oxide block copolymer as the selective layers by the process of selective-swelling-induced pore generation. A thin layers of block copolymer was spin-coated onto macroporous supports and activated the copolymer layers by soaking them in hot ethanol in order to induce the selective swelling of the polyethylene oxide microdomains. The hydrophilic polyethylene oxide blocks were enriched on the pore walls after swelling, rendering an inherent fouling resistance to the membranes. Protein fouling assessments proved that the membrane exhibited exceptional fouling resistance with a recovery ratio in water flux of nearly 100%. The fouling resistance is expected to be long-standing as the polyethylene oxide chains are covalently bonded to the membrane matrix. Gelde et al. (2018) presented a geometrical, chemical, optical and ionic transport changes associated with atomic layer deposition of TiO2-coating on the porous structure of two nanoporous alumina membranes. The two nanoporous alumina membranes were obtained by the two-step aluminum anodization method but with different pore size and porosity. With respect to the diffusive transport, the lower cation transport number and higher D−/D+ ratio exhibited by the nanoporous alumina membranes together with TiO2 possess pore radius of 13 nm. From the studies reviewed,

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the surface of nanoporous membranes can be uniformly and homogenously coated with a more resistive, robust and compatible material such as nanoparticle, while maintaining the original nanoporous structure. 4.2.1.2  Surface Grafting Modification Method Surface grafting is a method in which hydrophilic polymer chains are immobilized onto the surface of the membrane in order to provide a stable fouling resistance layer (Zhu et al. 2014). End-functionalized polymer chains may be grafted to the membrane surface or the grafting reaction can be advanced by polymerization from the membrane surface. In both cases, a dense brush layer on the solid surface is formed, which determines the surface properties (Minko 2008). The first step in the formation of the brush layer is the introduction of the reactive groups on the membrane surface. The introduction of the reactive groups is achieved by either exposing the membrane to low-temperature plasma (Rana and Matsuura 2010), photo grafting conditions (Peeva et  al. 2010), ultraviolet (Bilongo et  al. 2010) and electron beam radiation (Schulze et al. 2013) or introducing initiator sites (Zhu et al. 2008). The grafting of polymers brushes to a membrane surface offers a useful tool for membrane surface modification and functionalization. Hence, surface grafting is a modification method for preparing a well-tailored membrane surface with desired functions. Surface grafting method can also be attained by using a single monomer or with the help of a mixture of monomers (Goh et al. 2018). Numerous investigations have modified nanoporous membranes using coating method. Rahimpour et al. (2009) prepared poly(vinylidene fluoride) membrane through immersion precipitation method and modified by ultraviolet photo-grafting of hydrophilic monomers on the top membrane surface. Acrylic acid and 2-­hydroxyethylmethacrylate as acrylic monomers and 2,4-phenylenediamine and ethylene diamine as amino monomers were used at different concentrations in order to modify the membrane and improve the hydrophilicity with less fouling tendency. The antifouling properties and flux recovery of poly(vinylidene fluoride) membrane were improved by ultraviolet photo-grafting of hydrophilic monomers. Another study prepared the surface grafting of poly(ethylene glycol) onto commercial polyamide thin film composite membranes using ultraviolet photo-induced graft polymerization method (Ngo et al. 2017). The separation performance of the poly(ethylene glycol)-grafted membranes was highly improved, with a significant enhancement of flux at a great retention for the removal of the different objects in aqueous feed solutions. Furthermore, the antifouling property of the modified membranes was also clearly improved, with the higher maintained flux ratios and the lower irreversible fouling factors compared to the unmodified membrane. Very recently, a novel polyampholyte hydrogel and zwitterion polymer were grafted onto the surface of polyethersulfone membrane by copolymerizing a mixture of vinylsulfonic acid and [2-(methacryloyloxy) ethyl] trimethylammo nium chloride as the negatively and positively charged monomers, respectively (Zhang et  al. 2018). The process was carried out using various monomer ratios in the polymerization solution, and with

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N, N0 -methylenebisacrylamide as the crosslinker. The physicochemical, morphological and anti-fouling properties of the modified membranes were systematically investigated. Among all examined membranes, the zwitterion polyampholyte-­ modified membrane demonstrated the lowest adsorption of proteins, humic acid, and sodium alginate. The zwitterion polyampholyte-modified membrane also had low fouling and high flux recovery following the filtration with a protein or with an extracellular polymeric substance solution. The aim of surface grafting method which is the performance improvement by reduction of unwanted fouling compounds was achieved from the studies reviewed. However, surface grafting of fouling-­resistant polymer such as zwitterionic polymers could be the prospective strategies for the next-generation nanoporous membranes.

4.2.2  Prediction of Fouling in Nanoporous Membranes The investigation of fouling mechanism is very vital in defining optimum filtration condition; with respect to process parameters, product–membrane interactions and optimisation of several membrane attributes such as pore architecture (Affandy et al. 2013). Membrane fouling is affected by several factors such as pore blocking or pore constriction (Iritani et  al. 2010; Iritani 2013), concentration polarization (Kim et  al. 2009), cake formation (Mirsaeedghazi et  al. 2009; Nourbakhsh et  al. 2014) and solute adsorption (Iritani and Katagiri 2016). Identifying and understanding the fouling mechanisms in order to predict and control the behaviour of membrane over time is very significant (Torkamanzadeh et al. 2016). Across the different types of membrane, a transition from block-age models to cake filtration is observed after sometime. The particle size or the ratio of the particle size to the membrane pores is the key parameter for predicting fouling and choosing a suitable membrane (Hwang et  al. 2007). The study of analyzing particle retention within membrane pore has been done by quite a number of researchers (Bolton et al. 2005; Mondal and De 2010). It is very important to determine the mechanisms of fouling and to accurately predict the fouling of nano-porous membrane in order to know the behaviour of the membrane during separation processes. Hence, the following sub-­ sections reviews different models used in predicting fouling. 4.2.2.1  Pore Blocking Filtration Model The filtration blocking model is used to predict the maximum volumetric capacity (Vmax) of a membrane (Rajniak et al. 2008). Hence, a precise determination of the specific model that describes the fouling mechanism results to better sizing prediction during scaling up of filtration (Affandy et al. 2013). Blocking filtration laws are used for four different forms of fouling describing the deposit of particles on membranes. The filtration laws are complete, intermediate and standard blocking laws which describe the blocking of membrane pores, while cake filtration law is applied

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Fig. 4.6  Schematic representation of possible fouling mechanisms. (a) represent the standard blocking, (b) represent the complete blocking, (c) represent the caking; here, particle lands on another particle covering the pore, (d) solute represent landing on membrane material interpore. (Adapted from Griffithsa et al. 2014)

to the description of growth of filter cake which comprises of particle accumulations on the surface of the membrane (Iritani and Katagiri 2016). The schematic representation of different form of fouling is shown in Fig. 4.6. If the particle is adsorbed at the wall then the constriction effect of this particle on the pore is presumed to be distributed over the entire available surface area of the pore, as illustrated in Fig. 4.6(a). If a particle of size lands on an open pore, then complete pore blocking occurs (Fig. 4.6b). If the arriving of a particle size lands on a pore that has already been blocked, then the flux reduces through that part of the membrane by increasing the membrane thickness (Fig. 4.6c). If a particle lands on interpore surface, then the particle has no effect on the total flux. However, the particle adds to the depth of the membrane layer at that position. When the fraction of particles that land on interpore material increases, the time taken for the membrane to foul will also increase (Fig. 4.6d) (Griffithsa et al. 2014). Putting into consideration the possibility that a particle deposits on the surface of the membrane other than the pore, it is assumed that the probability that particle blocks an open pore is constant during filtration. Hence, the number of blocked pore is directly proportional to the filtrate volume v per the membrane effective area. The variation of the number of open pores during filtration is given by Eq. (4.7).





VNOP  N 0’  xv (4.7)

’ where VNOP is the variation of the numbers open pores, N 0 is the total number of open pores per unit effective membrane area at the beginning of the filtration, x is the number of particle blocking the pores per unit filtrate volume v. Here, the filtration rate directly proportional to the open pores can be written as:

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dv  kc p N 0’  xv dt (4.8)





where t is the filtration time, kc is the proportional constant, p is the filtration pressure. In cases where transition of fouling and the operative particle retention mechanisms take place during filtration, under constant pressure, Eq. (4.8) can be differentiated to have: 2



2

d2t  dt   dt   kc p0 x   kb   2 dv  dv   dv  (4.9)

where kb = kcp0x, is the blocking constant for complete blocking law. The four classical blocking filtration laws and the combination of filtration laws that describe the mechanism of fouling during particle filtration are as follows: Standard blocking is given in Eq. (4.10) with ks(m−1) as fouling parameter (Laska et al. 2005). 1

 kv  v   v0 t   1  s 0 t  A0  (4.10) 



Intermediate blocking is given in Eq. (4.11) with ki(m−3) as fouling parameter (Laska et al. 2005). V



1 ln 1  ki v0 t  ki (4.11)

Complete blocking is given in Eq. (4.12) with kb(s−1) as fouling parameter (Laska et al. 2005). v



v0 1  exp  kb t   kb  (4.12)

Cake blocking is given in Eq. (4.13) with kc(sm−6) as fouling parameter (Laska et al. 2005).



v

1 v0 kc

 1  2k v t   1  (4.13) 2 c 0

Intermediate-standard blocking is given in Eq. (4.14) with kic(m−1) and ks(m−1) as fouling parameter (Bolton et al. 2006). v

2 kic  v0 / A0  t  A0  In  1    kc  2  ks  v0 / A0  t  (4.14)

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Complete-standard blocking is given in Eq. (4.15) with kb(s−1)  and  ks(m−1) (Bolton et al. 2006). v

v0 kb

   2 kb t  1  exp    2  k  v / A  t    s 0 0    (4.15) 

where v is the filtrate volume (m3), v0 is the initial volumetric flowrate (m3/s), A0 is the initial membrane frontal area (m2), t is time(s) and ks, kb, ki, kc and kic are fouling parameters. Before the filtration blocking models can be applied, it is imperative to understand the dominant fouling mechanism. Nevertheless, the four classical blocking filtration models and the combination of filtration models have their limitations as a result of intrinsically simple presumptions regarding the filter and particulate characteristics (Affandy et al. 2013). The filter is presumed to consist of cylindrical pores while actual membranes envince highly interconnected, tortuous flow passages (Zydney and Ho 2002). However, the blocking filtration laws are relatively advantageous as a result of the easiness in the application of model to recognize the existing fouling mechanism from the experimental data of the flux decline at constant pressure. 4.2.2.2  Concentration Polarization Model All membrane separation processes experience concentration polarization. Concentration polarization is a fouling precursor. Increased concentration of solutes close to the surface of the membrane increases the tendency of fouling as a result of scaling, pore blocking and solute adsorption (Bhattacharjee 2017). Hence, concentration polarization is one of the major factors that influences the performance of membrane separation processes. The mechanism of concentration polarization is shown in Fig. 4.7. From Fig. 4.7, a solute mass balance in the concentration boundary is given by Eq. (4.16).



jv c  D

dc  jv C p dx (4.16)

where Cp is the solute concentration in the permeate and D is the diffusion coefficient. Rearranging and integrating the Eq. (4.16) with the following boundary conditions in Eqs. (4.17) and (4.18) gives the film model of Cp in Eq. (4.19).

= x 0;= C Cb (4.17)



x   ; C  Cm (4.18) Cm  C p



Cb  C p

 exp

jv k (4.19)

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Fig. 4.7  Mechanism of concentration polarization at the surface of a membrane. Convection carries solutes toward the membrane surface from the feed bulk and the ensuing concentration gradient sets off a diffusive back-­flux from the membrane surface toward the bulk feed solution. The competition between these two fluxes yields the final steady state concentration distribution near the membrane surface. (Adapted from Bhattacharjee 2017)

Eq. (4.19) gives the solute concentration profile in the polarized layer. Where Cb is the bulk concentration, δ is the thickness of the concentration boundary layer, and k is the mass transfer coefficient, given as: k



D  (4.20)

Cp and k, depend on the membrane properties and configuration, feed solution hydrodynamics, and solute properties. The expression for the concentration profile Eq. (4.19) is not informative because solute concentration at the membrane surface is not known. If the solute concentration Cm, is known, the concentration at any distance from the membrane surface will be known by employing Eq. (4.19). The only input to the surface of the membrane is the convective solute flux jCm. The outputs are the solute emerging from the permeate side of the membrane and the diffusive solute flux directed towards the feed bulk. Hence, a steady state mass balance for the solute at the membrane surface gives Eq. 4.21 (Bhattacharjee 2017).



jCm  k

dCm jC p dy (4.21)

Applying the assumption of the film theory, the concentration gradient obtained from Eq. (4.21) is valid everywhere in the hypothetical thin film. Hence, dropping the subscript from Eq. (4.19) yields Eq. (4.22).



k

dc   j C  C p  dy (4.22)

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Fig. 4.8  Schematic representation of the build-up of membrane resistances. The permeability coefficient depends on the membrane resistances. The resistances are caused by deposits on the membrane surface. (Adapted from Bhattacharjee 2017)

Setting Eq. 4.21 as boundary condition at the membrane surface and introducing dc  cons tan t, at y = 0, then the constant term becomes jCp. Eq. (4.21) into jc  k dy Thus, the basic steady state mass balance in film theory regarding the membrane surface condition is given by Eq. (4.21). From concentration polarization model, many parameters of fouling on the membrane are implicated in the control of composition of the active layer and sublayer, mass transfer coefficient, solute concentration on the active layer and the bulk concentration. The accurate prediction of concentration polarization phenomena is very crucial in order to properly design membrane processes because it improves trans-membrane osmotic pressure, solute passage, surface fouling and scaling phenomena (Kim and Hoek 2005). Here, concentration polarization is simply described as the build-up of a concentrated layer of rejected solutes near the membrane surface. The resistance of this layer is denoted by RCP with the total resistance given in Eq. 4.23 (Bhattacharjee 2017).

Rtotal  Rm  Rc  R f  R p  Ra  RCP (4.23)

All the resistances except Rm (if the membrane does not get compacted by pressure) have possibilities of increasing with time. The permeability coefficient depends on the membrane resistance. Thus, build-up of these resistances can result in permeate flux decline over time, hence fouling. The build-up of these resistances is schematically shown in Fig. 4.8.

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4.2.2.3  Cake Formation Model Caking is defined as a build-up of particle layers on the surface of the membrane. The layers provide a resistance in the form of an additional porous medium through which the feed must also permeate (Griffithsa et al. 2014). Investigations have confirmed that the mode of fouling changes during the course of membrane plugging (Grenier et al. 2008). The mode of fouling starts with the initial stages dominated by pore blocking, followed by complete blocking and the final stages are cake formation, which is principally accountable for the continued reduction in flux. The deposit of particles at the membrane surface can increase per layers, resulting to an important additional hydraulic resistance known as a cake resistance. A cake layer on the surface of a membrane is a resistance that is in series with the membrane resistance (Field 2010). The hydraulic resistivity is a function of the compressive pressure, which is related to the liquid pressure by Eq. (4.24).

p0  ps  pl (4.24) The specific resistance of the cake α is calculated according to the Eq. (4.25). u



p0   Rm   m  (4.25)

where m is the mass of filter cake per unit membrane area pl is equal to the filtration pressure p0 and at the cake-membrane interface, ps is the pressure in the solid. Rm is the effective hydraulic resistance of the membrane, μ is the viscosity of the filtrate. In the first stage of cake formation, filter cake steadily builds up on the filter medium as soon as filtration process starts. The surface area of the growing filter cake is equal to the area of the filter medium (Iritani 2003). At the first stage, on the assumption of negligible medium resistance, the reciprocal filtration rate, dθ/dv, is represented by Ruth’s equation for constant pressure filtration based on (Eq. 4.26) (Ruth 1935).



dq 2 = v dv K v (4.26)

where θ is the filtration time, v is the cumulative filtrate volume collected per unit effective medium area, Kv is the Ruth coefficient constant pressure filtration defined by Eq. (4.27).



Kv 

2 p 1  ms  m r s av

(4.27)

where p is the applied filtration pressure, is the mass fraction of the solid, αav is the average filtration resistance, m is the average cake mass and mr is the average ratio of wet to dry cake mass. Once the cake builds up to the underside of the membrane,

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the subsequent filter cake can only form inside the pore, consequently, the filtration area of the cake surface is reduced. The filtration rate decreases in accordance with the decrease in formation rate of the filter cake (Iritani 2003).

4.3  Energy Usage and Greenhouse Emission Energy and water have always been vital for the world’s social and economic growth. Their supply and use must be sustainable. The consumption of energy in the chemical industry accounts for about 15% of the consumption in the whole industrial sector. About 40% of such energy consumption accounted for by separation and refinement processes through distillation operations (Iwamoto and Kawamoto 2009a, b). The present universal energy challenge stems from inadequate fossil energy supplies and the environmental impacts for the entire energy challenge lifecycle, from mining and processing to greenhouse emissions, waste disposal and recycling (Le and Nunes 2016). The indicators of energy sustainability include the price of energy, environmental impacts and greenhouse gas emissions, availability of renewable energy sources, land requirements, water consumption and social impacts (Evans et  al. 2009). In addition to the use of energy and emissions at a manufacturing site, a product will have upstream or ‘embodied’ energy and carbon resulting from material extraction, transportation, and the early stages of production (Hammond and Jones 2008). The separation process for various types of water reuse and desalination is an energy intensive process. Achieving both a significant reduction of energy necessary for separation and an improvement of the efficiency of the separation process is one of the chemical industry’s priority issues when it comes to reducing the emissions of global greenhouse gas (Iwamoto and Kawamoto 2009a, b). Water reuse and desalination are beneficial to mankind; however, water reuse and desalination are more energy intensive than conventional water supply and treatment in some cases. Hence, raising concerns about water reuse and desalination carbon footprint (Cornejo et al. 2014). For example, the embodied energy of drinking water provision in Tampa, Florida was estimated to be 7.2 MJ/m3, whereas the embodied energy of water reuse and seawater reverse osmosis desalination were approximately 13–18 and 24–42 MJ/m3, respectively (Santana et al. 2014; Padowski and Jawitz 2012; Cornejo et al. 2014). Another example is in Californian, where seawater desalination has an energy and air emission footprint that is 1.5–2.5 times larger than that of imported water. The annual water needs (326 m3) of a typical Californian, when imported, requires 5.8 GJ of energy and generates 360 kg of CO2 equivalent emissions. With seawater desalination, energy use would rise to 14 GJ and generates 800  kg of CO2 equivalent emissions. Hence, meeting the water demand of Californian with desalination would consume 52% of the electricity generated by the state (Stokes and Horvath 2009). Other examples are: the average energy consumption for Germany and United Kingdom is 0.67 and 0.64 kWh/m3, respectively, and for Italy, consumption is between 0.40 and 0.70 kWh/m3,

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depending on the type of plant (Wang et al. 2016; Cantwell et al. 2010). However, the consumption of electrical energy per m3 of wastewater treated can vary, ranging from approximately 0.26–0.84 kWh/m3 (Venkatesh and Brattebo 2011; Pan et al. 2011). The range depends on operational and environmental characteristics, such as pollutant loads, plant size, plant age, types of material e.g. membrane and type of wastewater treatment plant (Guerrini et al. 2017).

4.3.1  T  he Role of Membranes in the Sustainability of Energy and Water Membrane technologies play a significant role in the sustainability of energy and water. Hence, membrane technologies still need to be improved in terms of cost of desalination and energy consumption, though plant size is another key performance driver of energy cost in wastewater treatment. In a conventional membrane technology, the osmotic pressure is balanced through the direct application of external pressure onto the salt water, which needs ultrahigh pressure and hence high energy consumption (Cohen-Tanugi and Grossman 2012). Granted, that some accomplishments have been achieved in the fabrication of membranes with high flux and good selectivity, the energy consumption of nanoporous membranes is however, still much higher than the thermos-dynamic limit (Ji et  al. 2017). The limitations of particular thermodynamic perspectives have to be clearly known. Hence, exergy reflects the ability to undertake useful work but does not represent well heating processes within an energy sector (Barrett et  al. 2018). Furthermore, membrane fouling can result to a serious decline of permeate selectivity, thereby increasing the energy demand, needing additional costs for cleaning and maintenance (Jhaveri et al. 2016). There are several membrane processes used in industrial practice, and the main focus of membrane technology is energy efficiency. However, fouling is one of the main barriers resisting an extensive adoption of energy efficient membranes for industrial applications (Shahkaramipour et al. 2017). For a nanoporous graphene centrifuge model presented by Tu et al. (2018), an attempt was made to provide a theoretical estimate for the lower bound of energy consumption, which was calculated by the following formula:





Energyinput Theoutcomeof freshwater (4.28)

The Energy Input is defined as the change in the kinetic energy that occurs when fresh water overcoming the thermodynamics free energy barrier is moving out of the centrifuge. The Fresh Water Outcome is defined as the total number of water molecules going through the filtration process in the simulation. The theoretical estimate showed that both the energy input and fresh water outcome increase linearly as a function of simulation time. Thus, the more the fresh water obtained the more the energy consumption. However, there can be savings in overall membrane

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materials or energy costs after the treatment of concentrate. Another way of achieving energy sustainability is to develop sustainable technologies in order to gradually replace non-renewable fossil fuels. These include energy conversion from renewable and natural resources into usable energy such as electricity and energy storage systems for long term or remote usage (Le and Nunes 2016). Clearly, there is generally, a need to stimulate improvements in resource use efficiency. There is also a need to encourage energy demand reduction from the ‘bottom-up’; induced by way of a portfolio of measures in order to counter market deficiencies, economic instruments, environmental regulation, and land use planning procedures (Barrett et al. 2018). Furthermore, using a zeolite separation membrane with a regular nanoporous structure is expected to be applied in the future in fields such as the dehydration, separation and refinement of organic compounds. Zeolite separation membrane will replace some of the current separation/refinement processes using the distillation method or replacing the entire process with the process of using separation membranes. The expectation of using zeolite separation membrane is that, there will be significant reduction in the energy consumption in the chemical industry (Iwamoto and Kawamoto 2009a, b). For example, Fig.  4.9 displays the estimation of the energy-saving effect that is expected in a plant that separates or refines the mixture of water and acetic acid, when conventional distilling columns are replaced with a system composed of nanoporous separation membrane modules. Assuming that the thermal energy needed for separation through the distillation process is

Fig. 4.9  Illustration of the estimation of energy-saving effect expected in a plant that separates or refines water and acetic acid when a nanoporous separation membrane system is introduced. The energy necessary in the water-selective nanoporous separation membrane process was estimated to be 27,000  kcal/h. An energy saving of about 85% was achieved. (Adapted from Iwamoto and Kawamoto 2009a, b)

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162,000 kcal/h, the energy necessary for separation or refinement through pervaporation in the water-selective nanoporous separation membrane process was estimated to be 27,000 kcal/h. Hence, an energy saving of about 85% was achieved in terms of necessary calories. In addition, if an acetic acid-selective separation membrane could be introduced, the necessary energy was estimated to be as low as 5200  kcal/h, which is a reduction in energy by more than 90% (Iwamoto and Kawamoto 2009a, b).

4.4  Climate Change Challenge The increased need for water has tensed local and regional water supplies in many areas around the globe and has led to increasing concern over water paucity, such as maintenance of adequate volumes of treatable water for human consumption (Runge and Mann 2008; Padowski and Jawitz 2012). The continued accessibility of clean and adequate water for people and nature is threatened by climate change (Bertule et al. 2018). Hence, the concerns of water paucity are compounded by uncertainties associated with the impacts of climate change, environmental regulation and further population growth on existing water resource (Means et al. 2005). The global climate change may alter hydrologic conditions and have a variety of effects on human settlements and ecological systems. The effects include changes in water supply and quality for domestic, irrigation, recreational, commercial, and industrial uses. Furthermore, the effects also include the instream flows that support aquatic ecosystems, recreation uses, hydropower, navigation, and wastewater assimilation (Hurd et al. 1999). Watersheds where water resources strained under current climate are most likely to be vulnerable to changes in mean climate and extreme events. For example, the climate change is projected to contribute to increasing sediment and nutrient loads due to the increased intensity of rainfall events (Xia et  al. 2016). Furthermore, in urban areas, heavy rainfall and flash floods cause the risk of sewer overflows, and consequently water contamination (Bertule et al. 2018). Hence, the great necessity to understand and identify specific climate change related water problems and their extent. Furthermore, analysing, mapping out and addressing specific water related climate challenges and associated risks to various communities and ecosystems are of utmost importance. The need to address the climate change has become major challenge for the water industry and membrane technology. The issue of climate change needs a fundamental assessment of energy usage and greenhouse gas emissions. Some targets have been given in the recent pronouncements call for greenhouse gas emissions. These targets comprise of all industrial sectors, including the water industry which is not a major greenhouse gas emitter. Nonetheless, membrane technology contributes in using the primary power, hence considered of being energy intensive (Fane 2011). The need for energy reduction in membrane technology is not the only challenge of the climate change issue. Another challenge of the climate change trends is leading to water paucity. However, the issues of fouling could be more challenging

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in membrane-based reclamation. For example, the much lower salinity means costs of production are 50% of seawater reverse osmosis and energy use is about 30% (Cote et al. 2005). The treatment of wastewater containing biodegradable organics can also contributes to greenhouse gas release (Fane 2011). The climate change drivers of water paucity and reduced greenhouse gas per unit water favour a stronger push to reclamation and reuse. The paucity of water opens up prospects for membrane technology, principally in the reclamation of used water.

4.5  Conclusion Pore size is the most important parameter in controlling the performance of nanoporous membranes; hence the assembling and adherence properties between nanoporous membranes and support structures should be totally understood. The development of nanoporous membranes with well-defined pores have the capability to enable precision size-based separations. The main advantage nanoporous membrane is that, its nanopores are well-ordered and uniform. Thus, the design of nanoporous membranes provides a sustainable alternative for the removal pollutants such as toxic metals, bacteria, viruses, organic materials from waste water. Nanoporous membranes have been used for various applications; nanoporous membranes used in biological and medical environments should have very good, biocompatibility and excellent physical and chemical stability. This chapter has shown the current findings of novel nanoporous membranes structures together with their fabrication methods. Theoretical modeling and simulations of nanoporous membranes and potential applications of nanoporous membranes have also been discussed. Methods used in mitigating fouling were discussed in conjunction with models that predict the relationship between the membrane structures and performance in order to understand the antifouling mechanism of nanoporous membranes. The effect of change in climate related factors on energy consumption and water paucity was addressed. Acknowledgements  The authors express their appreciation to Tshwane University of Technology, South Africa and Covenant University, Nigeria. Appreciation also goes to the Department of Higher Education, South Africa. This chapter was supported by the Department of Higher Education, South Africa.

References Abedini R, Nezhadmoghadam A (2010) Application of membrane in gas separation processes: its suitability and mechanisms. Pet Coal 52(2):69–80 Abraham J, Vasu KS, Williams CD, Gopinadhan K, Su Y, Cherian CT, Dix J, Prestat E, Haigh SJ, Grigorieva IV (2017) Tunable sieving of ions using graphene oxide membranes. Nat Nanotechnol 12(6):546–550

4  Fabrication and Potential Applications of Nanoporous Membranes for Separation…

161

Acikgoz C, Ling XY, Phang IY, Hempenius MA, Reinhoudt DN, Huskens J, Vancso GJ (2009) Fabrication of freestanding nanoporous polyethersulfone membranes using organometallic polymer resists patterned by nanosphere lithography. Adv Mater 21:2064–2067 Adiga SP, Jin C, Curtiss LA, Monteiro-Riviere NA, Narayan RJ (2009) Nanoporous membranes for medical and biological applications. Wiley Interdiscipl Rev Nanomed Nanobiotechnol 1:568–581 Affandy A, Keshavarz-Moore E, Versteeg HK (2013) Application of filtration blocking models to describe fouling and transmission of large plasmids DNA in sterile filtration. J Membr Sci 437:150–159 Ahmad SN (2013) Synthesis of multi-walled carbon nanotubes and their application in resin based nanocomposites. 6th Vacuum and Surface Sciences Conference of Asia and Australia (VASSCAA-6). J Phys Conf Ser 439(012009):1–8 Ahuja N, Kumar V, Rathee P (2012) Osmotic-controlled release oral delivery system: an advanced oral delivery form. Pharm Innov 1(7):116–124 Albert JNL, Epps TH III (2010) Self-assembly of block copolymer thin films. Mater Today 13(6):24–33 Altalhi T, Ginic-Markovic M, Han N, Clarke S, Losic D (2011) Synthesis of carbon nanotube (CNT) composite membranes. Membranes:37–47 Amin MT, Alazba AA, Manzoor U (2014) A review of removal of pollutants from water/wastewater using different types of nanomaterials. Adv Mater Sci Eng:1–24 Athanasekou CP, Romanos GE, Katsaros FK, Kordatos K, Likodimos V, Falaras P (2012) Very efficient composite titania membranes in hybrid ultrafiltration/photocatalysis water treatment processes. J Membr Sci 392-393:192–203 Bae TH, Lee JS, Qiu W, William JK, Jones CW, Nair S (2010) A high-performance gas- separation membrane containing sub-micrometer-sized metal–organic framework crystals. Angew Chem Int Ed 49:9863–9866 Baker RW (2004) Membrane technology and applications, 2nd edn. Wiley, Chichester Barrett J, Cooper T, Hammond GP, Pidgeon N (2018) Industrial energy, materials and products: UK decarbonisation challenges and opportunities. Appl Therm Eng 136:643–656 Bates FS (1991) Polymer-polymer phase behaviour. Science 251:898–905 Beck JS, Vartuli JC, RothWJ LME, Kresge CT, Schmitt KD, Chu CT-W, Olson DH, Sheppard EW, McCullen SB, Higgins JB, Schlenker JL (1992) A new family of mesopores molecular sieves prepared with crystal templates. J Am Chem Soc 114:10834–10843 Bertule M, Appelquist LR, Spensley J, Trærup SLM, Naswa P (2018) Climate change adaptation technologies for water. https://www.ctc-­n.org/sites/www.ctc-­n.org/files/resources/water_ adaptation_technologies_0.pdf. Accessed 13th June 2018 Bhattacharjee S (2017) Concentration polarization: early theories: water planet. http://www. waterplanet.com/wp-­content/uploads/2017/07/ConcentrationPolarization_FINAL_7-­11-­17. pdf. Assessed 12th June 2018 Bilongo TG, Remigy JC, Clifton MJ (2010) Modification of hollow fibers by UV surface grafting. J Membr Sci 364:304–308 Bolton GR, LaCasse D, Lazzara J, Kuriyel R (2005) The fiber-coating model of pharmaceutical depth filtration. AICHE J 51:2978–2987 Bolton G, LaCasse D, Kuriyel R (2006) Combined models of membrane fouling: development and application to microfiltration and ultrafiltration of biolo- gical fluids. J Membr Sci 277(1):75–84 Boukhvalov DW, Katsnelson MI, Son Y-W (2013) Origin of anomalous water permeation through graphene oxide membrane. Nano Lett 13(8):3930–3935 Bräuer P, Brzank A, Clark LA, Snurr RQ, Kärger J (2006) Guest-specific diffusion anisotropy in nanoporous materials: molecular dynamics and dynamic Monte Carlo simulations. Adsorp 12(6):417–422 Bunch JS, Verbridge SS, Alden JS, van der Zande AM, Parpia JM, Craighead HG, McEuen PL (2008) Impermeable atomic membranes from graphene sheets. Nano Lett 8:2458–2462 Cantwell J, King WR, Lorand RT (2010) Overview of state energy reduction programs and guidelines for the wastewater sector, water environment research foundation. IWA Publishing, London

162

O. Agboola et al.

Cao G (2004) Nanostructures and nanomaterials: synthesis, properties and applications. Imperial College Press, London, p 144 Celebi K, Buchheim J, Wyss RM, Droudian A, Gasser P, Shaorubalko I, Kye J, Lee C, Park HG (2014) Ultimate permeation across atomically thin porous graphene. Science 344:289–292 Chaturvedi S, Dave PN, Shah NK (2012) Applications of nano-catalyst in new era. J Saudi Chem Soc 16(3):307–325 Choi H, Al-Abed SR, Dionysiou DD (2009) Chapter 3: Nanostructured titanium oxide film- and membrane-based photocatalysis for water treatment. In: Savage N, Diallo M, Duncan J, Street A, Sustich R (eds) Nanotechnology applications for clean water. William Andrew, Boston, pp 39–46 Chougui A, Zaiter K, Belouatek A, Asli B (2014) Heavy metals and color retention by a synthesized inorganic membrane. Arab J Chem 7:817–822 Chowdhury SR, Chen Y, Wang Y, Mitra S (2009) Microwave-induced rapid nanocomposite using dispersed single-wall carbon nanotubes as the nuclei. J Mater Sci 44:1245–1250 Cohen-Tanugi D, Grossman JC (2012) Water desalination across nanoporous graphene. Nano Lett 17(7):3602–3608 Colson P, Henrist C, Cloots R (2013) Nanosphere lithography: a powerful method for the controlled manufacturing of nanomaterials: review article. J Nanomater V Article ID 948510:1–19 Cornejo PK, Santana MVE, Hokanson DR, Mihelcic JR, Zhang Q (2014) Carbon footprint of water reuse and desalination: a review of greenhouse gas emissions and estimation tools. J Water Reuse Desalin:238–252 Corry B (2008) Designing carbon nanotube membranes for efficient water desalination. J Phys Chem B112(5):1427–1434 Cote P, Siverns S, Monti S (2005) Comparison of membrane-based solutions for water reclamation and desalination. Desalin 182:251–257 Danion A, Disdier J, Guillard C, Abdelmalek F, Jaffrezic-Renual N (2004) Characterization and study of a single-TiO2-coated optical fiber reactor. Appl Catal B Environ 52:213–223 Das R, Ali ME, Hamid SBA, Ramakrishna S, Chowdhury ZZ (2014) Carbon nanotube membranes for water purification: a bright future in water desalination. Desalination 336:97–109 Ding J, Li X, Wang X, Zhang J, Yu D, Qui R (2015) Fabrication of vertical array CNTs/ Polyaniline composite membranes by microwave-assisted In situ polymerization. Nanoscale Res Lett 10:1–19 Diggle JW, Downie TC, Goulding CW (1969) Anodic oxide films on aluminum. Chem Rev 69:365–405 Dikin DA, Stankovich S, Zimney EJ, Piner RD, Dommett GHB, Evmenenko G, Nguyen ST, Rouff RS (2007) Preparation and characterization of graphene oxide paper. Nature 26(448):457–460 Dreyer DR, Park S, Bielawski CW, Ruoff RS (2010) The chemistry of graphene oxide. Chem Soc Rev 39:228–240 Du H, Li J, Zhang J, Su G, Li X, Zhao Y (2011) Separation of hydrogen and nitrogen gases with porous graphene membrane. The J Phys Chem C 115(47):23261–23266 Dumèe L, Sears K, Schütz J, Finn N, Duke M, Gray S (2010) Carbon nanotube based composite membranes for water desalination by membrane distillation. Desalin Water Treat 17(1–3):72–79 Elimelech M, Phillip WA (2011) The future of seawater desalination: energy, technology, and the environment. Science 333(6043):712–717 Epps TH, Epps TH III, DeLongchamp DM, Fasolka MJ (2007) Substrate surface energy dependent morphology and dewetting in an ABC triblock copolymer film. Langmuir 23:3355–3362 Evans A, Strezov V, Evans TJ (2009) Assessment of sustainability indicators for renewable energy technologies. Renew Sust Energ Rev 13:1082–1088 Fan HJ, Lee W, Scholz R, Dadgar A, Krost A, Nielsch K, Zacharias M (2005) Arrays for vertically aligned and hexagonally arranged ZnO nanowires: a template directed approach. Nanotechnol 16:913–917 Fane AG (2011) Membranes and the water cycle: challenges and opportunities. Appl Water Sci 1:3–9

4  Fabrication and Potential Applications of Nanoporous Membranes for Separation…

163

Field R (2010) Fundamentals of fouling. In: Membranes for water treatment: volume 4: edited by Klaus-Viktor Peinemann and Suzana Pereira Nunes. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim: pp. 1–9 Fu X, Zeltner WA, Anderson MA (1996) In: Kamat PV, Meisel D (eds) Semiconductor nanoclusters: physical. Chemical and Catalytic Aspects, Elsevier, Amsterdam, pp 445 Gao W (2015) Graphene oxide: reduction recipes, spectroscopy, and applications. Springer, Cham, p 29 Gelde L, Cuevas AL, Martínez de Yuso MV, Benavente J, Vega V, González AS, Prida VM, Hernando B (2018) Influence of TiO2-Coating layer on nanoporous alumina membranes by ALD technique. Coatings 8(60):1–12 Geng Y, Liu MY, Li J, Shi XM, Kim JK (2008) Effects of surfactant treatment on the mechanical and electrical properties of CNT/epoxy nanocomposites. Compos A 39:1876–1883 Goh PS, Ismail AF, Ng BC (2013) Carbon nanotubes for desalination: performance evaluation and current hurdles. Desalin 308:2–14 Goh PS, Lau WJ, Othman MHD, Ismail AF (2018) Membrane fouling in desalination and its mitigation strategies. Desalin 425:130–155 Gómez V, De La Pava I, Henao Q (2014) Stochastic diffusion of calcium ions through a nanopore in the cell membrane created by electroporation. Excerpt from the proceedings of the 2014 COMSOL conference in Boston Grenier A, Meireles M, Aimar P, Carvin P (2008) Analysing flux decline in dead-end filtration. Chem Eng Res Design 86(11):1281–1293 Griffithsa IM, Kumarb A, Stewart PS (2014) A combined network model for membrane fouling. J Colloid Interface Sci 432:10–18 Guerrini A, Romano G, Indipendenza A (2017) Energy efficiency drivers in wastewater treatment plants: a double bootstrap DEA analysis. Sustainability 9(1126):1–13 Hamley IW (1998) The physics of block copolymers. Oxford University Press, New York, p 1 Hammond GP, Jones CI (2008) Embodied energy and carbon in construction materials. Proc Instn Civil Engrs-Energy 161:87–98 Han JY, Fu J, Schoch RB (2008a) Molecular sieving using nanofilters: past, present and future. Lab Chip 8:23–33 Han E, Stuen KO, La YH, Nealey PF, GoPalan P (2008b) Effect of composition of substratemodifying random copolymers on the orientation of symmetric and asymmetric diblock copolymer domains. Macromolecules 41:9090–9097 Han J, Xu Z, Gao C (2013) Ultrathin graphene Nanofiltration membrane for water purification. Adv Funct Mater 23:3693–3700 Hauser W, Schwerdtfeger P (2012) Nanoporous graphene membranes for efficient 3He/4He separation. J Phys Chem Lett 3(2):209–213 He D, Sun W, Schrader T, Ulbricht M (2009) Protein adsorbers from surface grafted copolymers with selective binding sites. J Mater Chem 19(2):253–260 Hofs B, Ogier J, Vries D, Beerendonk EF, Cornelissen ER (2011) Comparison of ceramic and polymeric membrane permeability and fouling using surface water. Sep Purif Technol 79:365–374 Holister, P.  Vas Roman, C., Harper T (2013) Nanoporous Materials. Technology white paper nr. 5, Published by Cientifica. http://www.clubofamsterdam.com/conte ntarticles/01%20 Nanotechnology/Nanoporous%20Materials.pdf. Assessed 13th Oct 2017 Holowka EP, Bhatia SK (2014) Drug delivery: materials design and clinical perspective. Springer, New York, p 9 Homaeigohar S, Elbahri M (2017) Graphene membranes for water desalination. NPG Asia Mater 9(e427):1–16 Hong JS, Kim C (2007) Extension-induced dispersion of multi-walled carbon nanotubes in non-­ Newtonian fluid. J Rheol 51:833–850 Hosseni SS, Najari S (2016) Polymeric membranes for gas and vapor separations. In: Visakh PM, Nazarenko O (eds) Nanostructured polymer membranes, volume 2, applications. Wiley, p 100

164

O. Agboola et al.

Hu M, Mi B (2013) Enabling graphene oxide nanosheets as water separation membranes. Environ Sci Technol 47:3715–3723 Hu W, Peng C, Luo W, Lv M, Li X, Li D, Huang Q, Fan C (2010) Graphene-based antibacterial paper. ACS Nano 4:4317–4323 Huang S, Yin Y (2006) Transport and separation of small organic molecules through nanotubules. Anal Sci 22:1005–1009 Huang N, Lim H, Chia CH, Yarmo MA, Muhamad M (2011) Simple room-temperature preparation of high-yield large-area graphene oxide. Int J Nanomedicine 6:3443–3448 Huang H, Ying Y, Peng X (2014) Graphene oxide nanosheet: an emerging star material for novel separation membranes. J Mater Chem A 2(34):13772–13782 Huang L, Zhange M, Li C, Shi G (2015) Graphene-based membranes for molecular separation. J Phys Chem Lett 6:2806–2815 Hurd B, Leary N, Jones R, Smith J (1999) Relative regional vulnerability of water resources to climate change. J Am Water Resour Assoc 35(6):1399–1409 Hwang K-J, Liao C-Y, Tung K-L (2007) Analysis of particle fouling during microfiltration by use of blocking models. J Membr Sci 287:287–293 Iritani E (2003) Properties of filter cake in cake filtration and membrane filtration. Kona 21:19–39 Iritani E (2013) A review of modeling of pore blocking behaviours of membranes during pressurized membrane filtration. Dry Technol 31:146–162 Iritani E, Katagiri M (2016) Development of pore blocking filtration model in membrane filtration. KONA Powder Part J 33:179–202 Iritani E, Katagiri M, Tadama T, Sumi H (2010) Analysis of clogging behaviour of diatomaceous ceramic membrane during membrane filtration based on specific deposit. AICHE J 56:1748–1758 Iwamoto Y, Kawamoto H (2009a) Trends in research and development of nanoporous ceramic separation membranes – Saving energy by applying the technology to the chemical synthesis process. Sci Technol Trends:43–57 Iwamoto Y, Kawamoto H (2009b) Trends in research and development of nanoporous ceramic separation membranes – saving energy by applying the technology to the chemical synthesis process. Q Rev 32:43–58 Jarsch IK, Daste F, Gallop JL (2016) Membrane curvature in cell biology: an integration of molecular mechanisms: a review. J Cell Biol 214(4):375–387 Jeaze HBT, Koschine T, Staudt C, Raetzke K, Janiak C (2013) Correlation of gas permeability in a metal-organic framework MIL-101(Cr)-polysulfone mixed-matrix membrane with free volume measurements by positron annihilation lifetime spectroscopy (PALS). Membranes 3:331–353 Jhaveri JH, Jhaveri ZVP, Murthy V (2016) A comprehensive review on anti-fouling nanocomposite membranes for pressure driven membrane separation processes. Desalin 379:137–154 Ji Y-L, Gu B-X, An Q-F, Gao CJ (2017) Recent advances in the fabrication of membranes containing “ion pairs” for nanofiltration processes. Polym 9(715):1–49 Jiang DE, Cooper VR, Dai S (2009) Porous graphene as the ultimate membrane for gas separation. Nano Lett 9:4019–4024 Kabsch-Korbutowicz M, Urbanowska A (2010) Water treatment in integrated process using ceramic membranes. Polish J Environ Stud 19(4):731–737 Kaminsky W, Wiemann K (2003) Polypropene/silica-nanocomposites synthesized by in situ polymerization. Expected Mater Future 3:6–12 Kang MS, Martin CR (2014) Voltage charging enhances ionic conductivity in gold nanotube membranes. ACS Nano 8(8):8266–8272 Kaplan-Bekaroglu SS, Gode S (2016) Investigation of ceramic membranes performance for tannery wastewater treatment. Desalin Water Treat 57(37):17300–17307 Kärge J, Ruthven DM (2016) Diffusion in nanoporous materials: fundamental principles. Insights and challenges. New J Chem 40:4027–4048

4  Fabrication and Potential Applications of Nanoporous Membranes for Separation…

165

Karnik BS, Davies SH, Baumann MJ, Masten SJ (2005) Fabrication of catalytic membranes for the treatment of drinking water using combined ozonation and ultrafiltration. Environ Sci Technol 39(19):7656–7661 Kim S, Hoek EMV (2005) Modeling concentration polarization in reverse osmosis processes. Desalin 186:111–128 Kim M, Kim T (2013) Integration of nanoporous membranes into microfluidic devices: electrokinetic bio-sample pre-concentration. Analyst 138:6007–6015 Kim WG, Nair S (2013) Membranes from nanoporous 1D and 2D materials: a review of opportunities, developments, and challenges. Chem Eng Sci 104:908–924 Kim S, Lee S, Lee E, Sarper S, Kim C-H, Cho J (2009) Enhanced or reduced concentration polarization by membrane fouling in seawater reverse osmosis (SWRO) processes. Desalin 247:162–168 Kim HJ, Choi K, Baek Y, Kin DG, Shim J, Yoon J, Lee JC (2014) High-performance reverse osmosis CNT/polyamide nanocomposite membrane by controlled interfacial interactions. ACS Appl Mater Interfaces 6(4):2819–2829 Koenig SP, Wang L, Pellegrino J, Bunch JS (2012) Selective molecular sieving through porous graphene. Nat Nanotechnol 7:728–732 Kortunov P, Heinke L, Kärge J (2007) Assessing guest diffusion in nanoporous materials by Boltzmann’s method. Chem Mater 19(16):3917–3923 Kwak S-Y, Kim SH, Kim SS (2001) Hybrid organic/inorganic reverse osmosis (RO) membrane for bactericidal anti-fouling. 1. Preparation and characterization of TiO2 nanoparticle self-­ assembled aromatic polyamide thin-film-composite (TFC) membrane. Environ Sci Technol 35(11):2388–2394 Lalia BS, Kochkodan V, Hashaikeh R, Hilal N (2013) A review on membrane fabrication: structure, properties and performance relationship. Desalin 326:77–95 Laska ME, Brooks RP, Gayton M, Pujar NS (2005) Robust scale-up of dead end filtration: impact of filter fouling mechanisms and flow distribution. Biotechnol Bioeng 92(3):308–320 Le NL, Nunes PS (2016) Materials and membrane technologies for water and energy sustainability. Sustain Mater Technol 7:1–28 Le-Clech P, Chen V, Fane TA (2006) Fouling in membrane bioreactors used in wastewater treatment. J Membr Sci 284:17–53 Lee KP (2013) Fabrication and applications of nanoporous alumina membranes. PhD dissertation, University of Bath, UK Lee SB, Martin CR (2002) Electro-modulated molecular transport in gold-nanotube membranes. J Am Chem Soc 124:11850–11851 Lee K-J, Park H-D (2016) Effect of transmembrane pressure, linear velocity, and temperature on permeate water flux of high-density vertically aligned carbon nanotube membranes. Desalin Water Treat 57:26706–26717 Lee SB, Mitchell DT, Trofin LN, Nevanen TK, Soderlund H, Martin CR (2002a) Antibody- based bio-nanotube membranes for enantiomeric drug separations. Science 296:2198–2200 Lee CJ, Lyu SC, Kim HW, Park CY, Yang CW (2002b) Large-scale production of aligned carbon nanotubes by the vapor phase growth method. Chem Phy Lett 359(1–2):109–114 Lee HS, Im SJ, Kim JH, Kim HJ, Kim JP, Min BR (2008) Polyamide thin-film nanofiltration membranes containing TiO2 nanoparticles. Desalin 219(1–3):48–56 Lee KP, Morawska PM, Mattia D (2011) Investigation of enhanced fluid transport in nanoporous alumina membranes. International congress on membranes and membrane processes-­ Amsterdam, Netherlands, July 23rd-29th Lewisa SR, Datta S, Gui M, Coker EL, Huggins FE, Daunert S, Bachas L, Bhattacharyya D (2011) Reactive nanostructured membranes for water purification. PNAS 108(21):8577–8582 Li X, Fustin C-A, Lefèvre N, Gohy J-F, De Feyter S, De Baerdemaeker J, Egger W, Vankelecom IFJ (2010) Ordered nanoporous membranes based on diblock copolymers with high chemical stability and tunable separation properties. J Mater Chem 20:4333–4339

166

O. Agboola et al.

Li L, Schulte L, Clausen LD, Hansen KM, Jonsson GE, Ndoni S (2011) Gyroid nanoporous membranes with tunable permeability. ACS Nano 5(10):7754–7766 Li L, Ndoni S, Jonsson GE, Vigild ME (2012) Nanoporous polymers for membrane applications. Kgs. Lyngby: Technical University of Denmark, Department of Chemical Engineering Liu C (2014) Advances in membrane technologies for drinking water purification. In: Ahuja S (ed) Water quality and purification. Elsevier, p 91 Liu XQ, Chan-Park MB (2009) Facile way to disperse single-walled carbon nanotubes using a noncovalent method and their reinforcing effect in poly (methyl methyacrylate) composites. J Appl Polym Sci 114:3414–3419 Liu GQ, Zhao XS (2004) Nanoporous materials: science and engineering. Imperial College Press, London Liu Y, Xie B, Zhang Z, Zheng Q, Xu Z (2012) Mechanical properties of graphene papers. J Mech Phys Solids 60:591–605 Liu H, Dai S, Jiang D-E (2013) Permeance of H2 through porous graphene from molecular dynamics. Solid State Commun 175-176:101–105 Ma PC, Kim JK, Tang BZ (2007) Effects of silane functionalization on the properties of carbon nanotube/epoxy nanocomposites. Compos Sci Technol 67:2965–2972 Ma N, Quan X, Zhang Y, Chen S, Zhao H (2009) Integration of separation and photocatalysis using an inorganic membrane modified with Si-doped TiO2 for water purification. J Membr Sci 335:58–67 Ma N, Zhang Y, Quan X, Fan X, Zhao (2010) Performing a microfiltration integrated with photocatalysis using an Ag-TiO2/HAP/Al2O3 composite membrane for water treatment: evaluating effectiveness for humic acid removal and anti-fouling properties. Water Res 44:6104–6114 Ma L, Dong X, Chen M, Zhu L, Wang C, Yang F, Dong Y (2017) Fabrication and water treatment application of carbon nanotubes (CNTs)-based composite membranes: a review. Membranes 7(16):1–21 Majumder M, Chopra N, Andrews R, Hinds BJ (2005) Nanoscale hydrodynamics: enhanced flow in carbon nanotubes. Nature 438(7064):44 Makkonen-Craigi S, Yashinaii K, Paronen M (2014) Track-etched ultrafiltration polymer membranes produced by light ion irradiation. Arcada Working Papers 11:1–13 Malato J, Blanco AR, Fernandez-Alba A (2000) Aguera. Solar photocatalytic mineralization of commercial pesticides: acrinathrin. Chemosphere 40:403–409 Maphutha S, Moothi K, Meyyappan M, Iyuke SE (2013) A carbon nanotube-infused polysulfone membrane with polyvinyl alcohol layer for treating oil-containing waste. Water Sci Rep 3(1509):1–6 Martin CR, Nishizawa M, Jirage K, Kang M (2001) Investigations of the transport properties of gold nanotubule membranes. J Phys Chem B 105:1925–1934 Masuda H, Yamada H, Satoh M, Asoh H, Nakao M, Tamamura T (1997) Highly ordered nanochannel-­array architecture in anodic alumina. Appl Phys Lett 71:2770–2772 Masuda H, Nagae M, Morikawa T, Nishio K (2006) Long-range-ordered anodic porous alumina with reduced hole interval formed in highly concentrated sulfuric acid solution. Jpn J Appl Phys 45:L406–L408 Matteucci S, Yampolskii Y, Freeman BD, Pinnau I (2006) Transport of gases and vapors in glassy and rubbery polymers. In: Materials science of membranes for gas and vapor separation. Wiley, pp 1–47 Means EG, West N, Patrick R (2005) Population growth and climate change will pose tough challenges for water utilities. J Am Water Works Assoc 97(8):40–46 Meyn T, Bahn A, Leiknes TO (2008) Significance of flocculation for NOM removal by coagulation-­ ceramic microfiltration. Water Sci Technol Water Supply 8:691–700 Minko S (2008) Grafting on solid surfaces: “grafting to” and “grafting from” methods. In: Stamm M (ed) Polymer surfaces and interfaces. Springer, Berlin/Heidelberg, p 215

4  Fabrication and Potential Applications of Nanoporous Membranes for Separation…

167

Mirsaeedghazi H, Emam-Djomeh Z, Mousavi SMA (2009) Concentration of pomegranate juice by membrane processing: membrane fouling and changes in juice properties. J Food Sci Technol 46(6):538–542 Mondal S, De S (2010) A fouling model for steady state crossflow membrane filtration considering sequential intermediate pore blocking and cake formation. Sep Purif Technol 75:222–228 Nair RR, Wu HA, Jayaram PN, Grigorieva IV, Geim AK (2012) Unimpeded permeation of water through helium-leak-tight graphene-based membranes. Sci 335:442–444 Narayan R (2010) The use of nanomaterials in water purification. Mater Today 13(6):44–46 Ngo THA, Mori S, Tran DI (2017) Photo-induced grafting of poly(ethylene glycol) onto polyamide thin film composite membranes. J Appl Polym Sci 134(43):45454 Nishizawa M, Menon VP, Martin CR (1995) Metal nanotubule membranes with electrochemically switchable ion-transport selectivity. Sci 268:700–702 Nourbakhsh H, Alemi A, Emam-Djomeh Z, Mirsaeedghazi H (2014) Effect of processing parameters on fouling resistances during microfiltration of red plum and watermelon juices: a comparative study. J Food Sci Technol 51(1):168–172 O’Hern SC, Boutilier MSH, Idrobo J-C, Song Y, Kong J, Laoui T, Atieh M, Karnik R (2014) Selective tonic transport through tunable subnanometer pores in single-layer graphene membranes. Nano Lett 14:1234–1241 Olson DA, Chen L, Hillmyer MA (2007) Templating nanoporous polymers with ordered block copolymers. Chem Mater 20:869–890 Padowski JC, Jawitz JW (2012) Water availability and vulnerability of 225 large cities in the United States. Water Resour Res 48:1–16 Pan T, Zhu XD, Ye YP (2011) Estimate of life-cycle greenhouse gas emissions from a vertical subsurface flow constructed wetland and conventional wastewater treatment plants: a case study in China. Ecol Eng 37:248–254 Peeva PD, Pieper T, Ulbricht M (2010) Tuning the ultrafiltration properties of anti-fouling thin-­ layer hydrogel polyethersulfone composite membranes by suited crosslinker monomers and photo-grafting conditions. J Membr Sci 362:560–568 Peinemann KV, Nunes SP (2008) Membrane technology, volume 1: membranes for life sciences. Wiley-Vch, Weinheim Pendergast TMM, Hoek EMV (2011) A review of water treatment membrane nanotechnologies. Energy Environ Sci 4:1946–1971 Perreault F, Fonseca de Faria A, Elimelech M (2015) Environmental applications of graphene-­ based nanomaterials. Chem Soc Rev 44:5861–5896 Phillip WA, O’Neill B, Rodwogin M, Hillmyer MA, Cussier EL (2010) Self-assembled block copolymer thin films as water filtration membranes. App Mater Interfaces 2:847–853 Poinern GEJ, Ali N, Fawcett D (2011) Progress in nano-engineered anodic aluminum oxide. Membrane development. Mater 4:487–526 Popp A, Engstler J, Schneider JJ (2009) Porous carbon nanotube-reinforced metals and ceramics via a double templating approach. Carbon 47(14):3208–3214 Prihasto N, Liu QF, Kim SH (2009) Pre-treatment strategies for seawater desalination by reverse osmosis system. Desalin 249:308–316 Rahimpour A, Madaeni SS, Zereshki S, Mansourpanah Y (2009) Preparation and characterization of modified nano-porous PVDF membrane with high antifouling property using UV photo-­ grafting. Appl Surf Sci 255:7455–7461 Rajeshri W, Bajaj A (2010) Once a day osmotic drug delivery system for highly water soluble pramipexole. J Chem Pharm Res 2(2):136–146 Rajniak P, Tsinontides SC, Pham D, Hunke WA, Reynolds SD, Chern RT (2008) Sterilizing filtration-principles and practice for successful scale-up to manufacturing. J Membr Sci 325(1):223–237 Ramirez P, Apel PY, Cervera J, Mafe S (2008) Pore structure and function of synthetic nanopores with fixed charges: tip shape and rectification properties. Nanotechnol 19:1–12

168

O. Agboola et al.

Rana D, Matsuura T (2010) Surface modification for antifouling membranes. Chem Rev 110:2448–2471 Reddy ALM, Shaijumon MM, Gowda SR, Ajayan PM (2009) Coaxial MnO2/carbon nanotube array electrodes for high-performance lithium batteries. Nano Lett 9(3):1002–1006 Ridgwaya HF, Orbella J, Gray S (2017) Molecular simulations of polyamide membrane materials used in desalination and water reuse applications: recent developments and future prospects. J Membr Sci 524:436–448 Roy S, Bhadra M, Mitra S (2014) Enhanced desalination via functionalized carbon nanotube immobilized membrane in direct contact membrane distillation. Sep Purif Technol 136:58–65 Runge J, Mann J (2008) State of the industry report 2008- charting the course ahead. J Am Water Works Assoc 100(10):61–74 Russo P, Hu A, Compagnini G (2013) Synthesis, properties and potential applications of porous graphene: a review. Nano-Micro Lett 5(4):260–273 Ruth BF (1935) Study in filtration III: derivation of general filtration equations. Ind Eng Chem 27:708–723 Ruthven DM (2009) Diffusion through porous media: Ultrafiltration membrane Permeation and Molecular Sieving. diffusion-­fundamentals.org 11(13):1–20 Safaei S, Tavakoli R (2017) On the design of graphene oxide nanosheets membranes for water desalination. Desalin 422:83–90 Santana MVE, Zhang Q, Mihelcic JR (2014) Influence of water quality on the embodied energy of drinking water treatment. Environ Sci Technol 48:3084–3091 Santo JLC, Oliveira R, Crespo J (2012) Hybrid modeling of membrane processes. In: Rios G, Centi G, Kanellopoul N (eds) Nanoporous materials for energy and the environment. CRC Press, Boca Raton, p 142 Sartowska B, Starosta W, Apel P, Orelovitch O, Blonskaya I (2013) Polymeric track etched membranes application for advanced porous structures formation. Acta Phys Polonica A 123(5):819–821 Savage N, Diallo MS (2005) Nanomaterials and water purification: opportunities and challenges. J Nanopart Res 7:331–342 Scharlach K, Kaminsky W (2008) New polyolefin-nanocomposites by in situ polymerization with metallocene catalysts. Macromol Symp 261:10–17 Schulze A, Maitz MF, Zimmermann R, Marquardt B, Fischer M, Werner C, Went M, Thomas I (2013) Permanent surface modification by electron-beam-induced grafting of hydrophilic polymers to PVDF membranes. RCS Adv 3:22518–22526 Shahkaramipour N, Tran TN, Ramanan S, Lin H (2017) Membranes with surface-enhanced antifouling properties for water purification. Membranes 7(13):1–18 Shannon MA, Bohn PW, Elimelech M, Georgiadis JG, Mariṅas BJ, Mayes AM (2008) Science and technology for water purification in the coming decades. Nature 452:301–310 Shirasaki N, Matsushita T, Matsui Y, Ohno K (2008) Effects of reversible and irreversible membrane fouling on virus removal by a coagulation–microfiltration system. J Water Supply Res Technol AQUA 57:501–506 Siepmann J, Kranz H, Bodmeier R, Peppas NA (1999) HPMC-matrices for controlled drug delivery: a new model combining diffusion, swelling, and dissolution mechanisms and predicting the release kinetics. Pharm Res 16(11):1748–1756 Siepmann J, Siegel RA, Siepmann F (2012) Diffusion controlled drug delivery systems. In: Siepmann J et  al (eds) Fundamentals and applications of controlled release drug delivery. Advances in delivery science and technology, Controlled release society, Springer, New York, pp 127–128 Silva P, Han S, Livingston A (2005) Solvent transport in organic solvent nanofiltration membranes. J Membr Sci 262:49–59 Simon L (2011) A computational procedure for assessing the dynamic performance of diffusion-­ controlled transdermal delivery devices. Pharma 3:485–496

4  Fabrication and Potential Applications of Nanoporous Membranes for Separation…

169

Singh R, Maru VM, Moharir PS (1998) Complex chaotic systems and emergent phenomena. J Nonlinear Sci 8:235–259 Snyder MA, Tsapatsis M (2007) Hierarchical nano manufacturing: from shaped zeolite nanoparticles to high-performance separation membranes. Angew Chem-Int Edition 46(40):7560–7573 Snyder MA, Vlachos DG, Katsoulakis MA (2002) A novel approach to molecular modeling of transport through inorganic nanoporous membranes. Fuel Chem Div Prepr 47(1):211–212 Snyder JL, Clark A Jr, Fang DZ, Gaborski TR, Striemer CC, Fauchet PM, McGrath JL (2011) An experimental and theoretical analysis of molecular separations by diffusion through ultrathin nanoporous membranes. J Membr Sci 369:119–129 Sombatsompop KM (2007) Membrane fouling studies in suspended and attached growth membrane bioreactor systems. Thesis, Asian Institute of Technology Song H, Shao J, He Y, Liu B, Zhong X (2012) Natural organic matter removal and flux decline with PEG-TiO2-doped PVDF membranes by integration of ultrafiltration with photocatalysis. J Membr Sci 405-406:48–56 Sparreboom W, Van Den Berg A, Eijkel J (2009) Principles and applications of nanofluidic transport. Nat Nanotechnol 4:713–720 Stevenson CL, Santini JT, Langer R (2012) Reservoir-based drug delivery systems utilizing microtechnology. Adv Drug Deliv Rev 64(14):1590–1602 Stokes JR, Horvath A (2009) Energy and air emission effects of water supply. Environ Sci Technol 43:2680–2687 Strathmann H (2000) Membrane separation processes, 1. Principles. In: Ullmann’s encyclopedia of industrial chemistry. Wiley-VCH Verlag GmbH & Co. KGaA Stroeve P, Ileri N (2011) Biotechnical and other applications of nanoporous membranes. Trends Biotechnol 29(6):259–266 Stylianou SK, Szymanska K, Katsoyiannis LA, Zouboulis AI (2015) Novel water treatment processes based on hybrid membrane-ozonation systems: a novel ceramic membrane contactor for bubbleless ozonation of emerging micropollutants. J Chem 214927:1–12 Suk ME, Aluru N (2010) Water transport through ultrathin graphene. J Phys Chem Lett 1:1590–1594 Sun C, Boutilier MSH, Au H, Poesio P, Bai B, Karnik R, Hadjiconstantinou NG (2014) Mechanisms of molecular permeation through nanoporous graphene membranes. Langmuir 30:675–682 Sun C, Wen B, Bai B (2015a) Application of nanoporous graphene membranes in natural gas processing: molecular simulations of CH4/CO2, CH4/H2S and CH4/ N2 separation. Chem Eng Sci 138:616–621 Sun C, Wen B, Bai B (2015b) Recent advances in nanoporous graphene membrane for gas separation and water purification. Sci Bull 60(21):1807–1823 Swaminathan VV, Gibson LR II, Pinti M, Prakash S, Bohn PW, Shannon MA (2012) Ionic transport in nanocapillary membrane systems. J Nanopart Res 14:951–965 Szymczyk A, Fievet P (2005) Investigating transport properties of nanofiltration membranes by means of a steric, electric and dielectric exclusion model. J Membr Sci 252:77–88 Tanahashi M (2010) Development of fabrication methods of filler/polymer nanocomposites: with focus on simple melt-compounding based approach without surface modification of nanofillers. Mater 3:1593–1619 Tomas B (2013) Mass transport in nanoporous materials: new insights from micro- imaging by interference microscopy. PhD dissertation, Universität Leipzig Tong HD, Jansen HV, Gadgil VJ, Bostan CG, Berenschot E, van Rijn CJM, Elwenspoek M (2004) Silicon nitride nanosieve membrane. Nano Lett 4:283–287 Torkamanzadeh M, Jahanshahi M, Peyravi M, Rad AS (2016) Comparative experimental study on fouling mechanisms in nano-porous membrane: cheese whey ultrafiltration as a case study. Water Sci Technol 74(12):2737–2750 Tu Q, Li T, Deng A, Zhu K, Liu Y, Li S (2018) A scale-up nanoporous membrane centrifuge for reverse osmosis desalination without fouling. Technol 6(1):36–48 Ulbricht M (2006) Advanced functional polymer membranes. Polym 47:2217–2262

170

O. Agboola et al.

Velleman L, Shapter JD, Losic D (2008) International conference on nanoscience and nanotechnology, Melbourne Convention Centre, Melbourne, Victoria, Australia, 25th–29th Feb, 2008 Venkatesh G, Brattebo H (2011) Energy consumption, costs and environmental impacts for urban water cycle services: case study of Oslo (Norway). Energy 36:792–800 Volder MFLD, Tawfick SH, Baughman RH, Hart AJ (2013) Carbon nanotubes: present and future commercial applications. Sci 339:535–539 Wang L, Song XJ, Wang T, Wang S, Wang Z, Gao C (2015) Fabrication and characterization of polyethersulfone/carbon nanotubes (PES/CNTs) based mixed matrix membranes (MMMs) for nanofiltration application. Appl Surf Sci 330:118–125 Wang H, Yang Y, Keller AA, Li X, Feng S, Dong Y, Li F (2016) Comparative analysis of energy intensity and carbon emissions in wastewater treatment in USA, Germany, China and South Africa. Appl Energy 184(15):873–881 Wang L, Boutilier MSH, Kidambi PR, Jang D, Hadjiconstantinou NG, Karnik R (2017) Fundamental transport mechanisms, fabrication and potential applications of nanoporous atomically thin membranes: review. Nature Nanotechnol 12:509–522 Wang Z, Wu A, Ciacchi LC, Wei G (2018) Recent advances in nanoporous membranes for water purification. Nano 8(65):1–19 Wanichapicharta P, Chittrakarn T, Sujaritturakarn W, Coster HGL (2000) Production of nuclear-­ track etched membranes. Sci Asia 26:175–179 Whitby M, Quirke N (2007) Fluid flow in carbon nanotubes and nanopipes. Nat Nanotechnol 2:87–94 Whitesides GM, Grzybowski B (2002) Self-assembly at all scales. Sci 295:2418–2421 Winans JD, Smith KJP, Gaborski TR, Roussie JA, McGrath JL (2016) Membrane capacity and fouling mechanisms for ultrathin nanomembranes in dead-end filtration. J Membr Sci 499:282–289 Xia R, Zhang Y, Critto A, Wu J, Fan J, Zheng Z, Zhang Y (2016) The potential impacts of climate change factors on freshwater eutrophication: implications for research and countermeasures of water management in China. Sustainability 8(3):229–245 Xu Q, Zhang W (2016) Next-generation graphene-based membranes for gas separation and Water Purifications. In: Silva A (ed) Advances in Carbon Nanostructures. InTech, Croatia, p 41 Xu D, Shi X, Guo G (2000) Electrochemical preparation of CdSe nanowire arrays. J Phys Chem B 104:5061–5063 Xu Q, Xu H, Chen J, Lv Y, Dong C, Sreeprasad TS (2015) Graphene and graphene oxide: advanced membranes for gas separation and water purification. Inorg Chem Frontiers 2:417–424 Yampolskii Y (2012) Polymeric gas separation membranes. Macromolecules 45:3298–3311 Yanagishita T, Masuda H (2015) High-throughput fabrication process for highly ordered through-­ hole porous alumina membranes using two-layer anodization. Electrochim Acta 184:80–85 Yanagishita T, Kato A, Masuda H (2017) Preparation of ideally ordered through-hole anodic porous alumina membranes by two-layer anodization. Jpn J Appl Phys 56:1–4 Yang H, Wang Z, Lan Q, Wang Y (2017) Antifouling ultrafiltration membranes by selectiveswelling of polystyrene/ poly(ethylene oxide) block copolymers. J Membr Sci 542:226–232 Zhang ZF, Yang XW, Zhao YC, Chen QH, Sun JS (2003) Fabrication of anodized aluminum oxide membrane with nanometer pores. Trans Nonferrous Met Soc China 13(2):298–301 Zhang HM, Quan X, Chen S, Zhao H (2006) Fabrication and characterization of silica/titania nanotubes composite membrane with photocatalytic capability. Environ Sci Technol 40:6104–6109 Zhang WM, Li J, Cao LX, Wang YG, Guo W, Liu KX, Xue JM (2008) Fabrication of nanoporous silicon dioxide/silicon nitride membranes using etched ion track technique. Nucl Instrum Methods Phys Res B 266:3166–3169 Zhang Q, Ghosh S, Samitsu S, Peng X, Ichinose I (2011) Ultrathin freestanding nanoporous membranes prepared from polystyrene nanoparticles. J Mater Chem 21(6):1684–1688

4  Fabrication and Potential Applications of Nanoporous Membranes for Separation…

171

Zhang M, Hou C, Halder A, Wang H, Chi Q (2017) Graphene papers: smart architecture and specific functionalization for biomimetics, electrocatalytic sensing and energy storage. Mater Chem Front 1:37–60 Zhang W, Yang Z, Kaufman Y, Bernstein R (2018) Surface and anti-fouling properties of apolyampholyte hydrogel grafted onto a polyethersulfone membrane. J Colloid Interface Sci 517:155–165 Zhao X, Meng G, Han F, Li X, Chen B, Xu Q, Zhu X, Chu Z, Kong M, Huang Q (2013a) Nano containers made of various materials with tunable shape and size. Sci Rep 3(2238):1–7 Zhao H, Li H, Yu H, Chang H, Quan X, Chen S (2013b) CNTs–TiO2/Al2O3 composite membrane with a photocatalytic function: fabrication and energetic performance in water treatment. Sep Purif Technol 116:360–365 Zhu LP, Dong HB, Wei XZ, Yi Z, Zhu BK, Xu YY (2008) Tethering hydrophilic polymer brushes onto PPESK membranes via surface-initiated atom transfer radical polymerization. J Membr Sci 320:407–415 Zhu Y, Wang D, Jiang L, Jin J (2014) Recent progress in developing advanced membranes for emulsified oil/water separation. Asia Mater 6:1–11 Zydney AL, Ho C-C (2002) Scale-up of microfiltration systems: fouling phenomena and Vmax analysis. Desalin 146:75–81

Chapter 5

Nanomaterials for Effective Control of Algal Blooms in Water Rong Cheng, Liang-jie Shen, Shao-yu Xiang, Dan-yang Dai, and Xiang Zheng

Abstract Algal blooms resulted from eutrophication has increasingly occurred worldwide and poses serious threats to water environment, tourism and aquatic ecosystems. In addition, the toxins released by living or dead algae are harmful to aquatic animals or even the human body. Hence, the effective control of algal blooms becomes an urgent front-burner problem. Nanotechnology, the emerging means, has produced great repercussions in recent decades because of its unique physical and chemical properties such as small-size effect, quantum-size effect and so forth. Considering the source controlling, short-term strategy and health risk, the removal of nutrient, algae or algae toxins from the water using nanotechnology is reviewed in this text. Firstly, the removal performance and mechanisms of phosphorus by nanomaterials are summarized from the view of source controlling. And the major point is that the nanoparticles present extremely high capacity (5–200  mg P·g−1) and specific affinity to phosphorus. Then, the effect on algae removal by nanomaterials is analyzed from the short-term strategies. And the removal efficiency is increased with the dose of nanoparticles and the algae are removed and destructed through the photocatalytic oxidation. Furthermore, mechanisms of photocatalytic removal of algae are discussed. And the algae toxins (e.g. microcystin-LR) can be adsorbed or degraded by nanoparticles (e.g. magnetic materials or nano-­ photocatalyst). Finally, the current challenges are outlined and future directions to achieve efficient and economic control of algal blooms are discussed. Keywords  Algal bloom · Nanomaterials · Eutrophication · Phosphorus · Algal toxins · Microcystins

R. Cheng (*) · L.-j. Shen · S.-y. Xiang · D.-y. Dai · X. Zheng (*) School of Environment and Natural Resources, Renmin University of China, Beijing, China e-mail: [email protected]; [email protected]; [email protected]; [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_5

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5.1  Introduction Algae bloom is mainly caused by the eutrophication, which is the phenomenon of excessive phytoplankton production in rivers, lakes and reservoirs, resulted from increases in levels of nutrients (phosphorus and nitrogen compounds) (Zamparas and Zacharias 2014). The organic matters produced by algae affect the color, taste and odor of drinking water and even a number of cyanobacterial species excrete toxic metabolites (Microcystin-LR, Microcystin-RR and so forth), which can cause worse health problems (O’Neil et al. 2012). Phosphate is one of the important nutrients which are indispensable for all creatures on the earth. Excessive presence of phosphorous in water bodies, however, is one of the major causes to eutrophication, which leads to the outbreaks of algae bloom, diminishes dissolved oxygen, lowers water quality, and reduces biodiversity in aquatic ecosystems (Hartmann et al. 2010; Zhang et al. 2009; Yang et al. 2013; Saha et al. 2009). As shown in Fig. 5.1, the problem of eutrophication all over the world is abominable and urgent to be solved (Liu et al. 2016). So the corresponding limiting concentration of phosphate in surface water and products containing phosphorus is provided in almost all countries, such as 0.010 ~ 0.100 mg·L−1 for river and 0.005 ~ 0.050 mg·L−1 for lakes and reservoirs in Australian, 0.02 ~ 0.40 mg·L−1 for lakes and reservoirs in China, less than 0.3 g per standard dose for cleaning agent of kitchen utensils and less than 0.5 g per standard dose for washing powder in European Union, less than 50 μg·L−1 for United States Environmental Protection Agency (USEPA) and so forth. The high concentration of 2− − phosphate (e.g. PO3− 4 , HPO 4 and H 2 PO 4 ) in water is attributed to various sources,

Fig. 5.1  The proportion of eutrophic water bodies in various regions

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including agricultural pollution, municipal or industrial wastewater disposal and natural solubilization of rocks (Zhou et al. 2001; Pieterse et al. 2003). Therefore, it is of vital importance to reduce and control the level of phosphorous in the industrial, urban, and agricultural wastewater prior to its discharge into environment, and phosphate removal from water has attracted considerable research interest in the last few decades (Kasp et al. 2005). In addition, the water is in a long-term anoxic state caused by the algae bloom, which leads to the death of a large number of water organisms and the stink of water quality, and affects the healthy operation of the whole aquatic ecosystem (Wolf et al. 2017). To make matters worse, such problems led to aquaculture bankruptcy and deficits. And it is worrisome that algal toxins produced from algae blooms are highly toxic to both of the aquatic organisms and humans with incalculable consequences (Meneely and Elliott 2013; Wiegand and Pflugmacher 2005). In the face of frequent algae bloom, and the consequent losses, how to solve the problems becomes urgent. On the whole, the most important and primary problem is the excess nutrient in water, especially phosphorus (Chouyyok et al. 2010). What we need to consider next is the removal of a large amount of algae in the water (Barrado-Moreno et al. 2017). Then, the removal of algae toxins released into the body of water after algae bloom is also a challenging task (Meneely and Elliott 2013). Considering the source controlling, short-term strategy and health risk, the removal of phosphate, algae or algae toxins from the water using nanotechnology is reviewed in this text.

5.2  Removal of Phosphate by Nano-materials in Water Traditionally, several methods, including chemical precipitation, biological treatment, ion exchange and adsorption, have been investigated to remove phosphorous from aqueous solution. In particular, the adsorption-based process is considered as one of the promising routes, due to ineffectiveness of toxic substance, and recyclability of adsorbents (Yu and Chen 2015). In the last decades, a lot of efforts have been devoted to the exploitation of various adsorbents for fast removal of phosphate in water bodies including natural red mud, ash, iron oxide and metal-based materials (Haghseresht et al. 2009; Lu et al. 2009; Zeng et al. 2004). Various transitional metallic oxides are proved to be efficient adsorbents for phosphate retentions by strong inner-sphere complexation of metallic oxides such as zirconium oxides and iron oxides. The development of metal (e.g. Al, Fe, Ti, and so on.) doped or modified materials as adsorbents for enhanced phosphate removal has become an increasing area of research, thanks to the specific adsorption between metal active sites and phosphate in solution (Delaney et al. 2011; Li et al. 2013). Compared to other metals, lanthanum-based adsorbents show a number of promising advantages in phosphate removal, including superior adsorption capacity, wide operating pH range and high removal rate in a low phosphate concentration. It’s reported that lanthanum oxides are confirmed to possess ultra-high activity for phosphate sequestration,

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approximately ten times greater than that of famous aluminum oxides powder (Xie et al. 2015; Lürling et al. 2014). In the 1970s, phosphate precipitation by lanthanum was found to be more effective over a wider pH range (4.5 ~ 8.5) than either Fe3+ or aluminium salts (Melnyk 1974). It is known that rhabdophane (LaPO4) is insoluble in aqueous medium, it is thus imaginable that lanthanum or lanthanum oxide based materials should facilitate the adsorption or removal of phosphate due to the formation of LaPO4 (Kuroki et  al. 2014). Recently, there has been tremendous interest, concentrating on the nanosized lanthanum-based adsorbents and their potential in different practical applications (Huang et al. 2014a, b, 2015a, b; Zong et al. 2017; Lai et al. 2016). Some review papers have been devoted to the removal of phosphate in terms of mesoporous materials, lanthanum modified bentonite and so on (Huang et al. 2017; Copetti et al. 2016). However, there have been few reviews on the development of nanosized lanthanum-based adsorbents especially targeting at phosphate removal. In this work, the synthesis and performance of various nanosized La-based adsorbents were summarized, as well as the influence factors (pH, ionic strength, and coexisting anion). According to the properties and types of carriers, the nanosized La-based adsorbents that have been used for phosphate control are classified into five categories: La-clay mineral adsorbents, La-metallic compounds, La-organics adsorbents, La-silica adsorbents and La-others. To provide a global overview of the state of the art, there are nearly two hundred scientific publications dealing with the removal of phosphate by La-based adsorbents. Figure 5.2 shows the numbers of publications on nanosized La–based adsorbents for phosphate removal in Web of Science. As shown in the Fig. 5.2a, the research on nanosized La-based adsorbents for phosphate removal is generally on the rise, especially in recent years. In Fig. 5.2b, the main status is occupied by La-clay minerals accounting for 48.2%. It’s understandable that clay minerals are an important class of adsorbents that comprise of a broad range of porous crystalline solids and based essentially on tetrahedral networks which encompass channels and cavities. For La-organic adsorbents like La-chitosan, Chitosan (poly-β-(1  →  4)-2-amino-2-deoxy-D-glucose) is a natural polysaccharide produced by the N-deacetylation of chitin and its high amino content on the polymer matrix provides selectivity to the adsorption process.

5.2.1  R  emoval of Phosphate by Nanosized La-Based Adsorbents 5.2.1.1  Preparation and Mechanism of Nanosized La-Based Adsorbents The adsorbent has high specific surface area and abundant pores, such as 600 ~ 900 m2·g−1 for bentonite, 400 ~ 800 m2·g−1 for zeolite. The large surface area leads to great surface energy, together with its layered structure and the type and distribution of elements in the structure, which determine its strong adsorption

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Fig. 5.2 (a) Numbers of publications on nanosized La-based adsorbents per year (numbers of publications on adsorbents were inseted); (b) Percentages of different types of nanosized La-based adsorbents

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capacity. However, single adsorbent fails to achieve the specific selectivity and its structure is not optimal. So further modification is required, and La modification has gradually attracted the interest of scholars in recent years. And adsorbents with good property generally serve as the matrix for immobilizing the nanosized La compounds. Preparation of Nanosized La-Based Adsorbents Nanosized La-based adsorbents have been used for phosphate removal for approximately 40 years. Various types of adsorbents have been synthesized and studied for the recovery of water. 1. La-clay mineral adsorbents La-clay mineral adsorbents are one of the most widely used materials and successfully applied for the phosphate removal in both water and wastewater because of the easy access, low cost and excellent adsorption of clay minerals (Epe et al. 2017). Typically, impregnation is used most for preparing the La-clay mineral adsorbents, by which the lanthanum ions (0.112 nm for ionic radius of La3+) would enter the pores and surface of clay minerals due to the mode of ion exchange process and free diffusion (Kuroki et  al. 2014; Haghseresht et  al. 2009). Then, the sample was dried at relatively higher temperatures (e.g. 383  K) to form lanthanum oxides. The preparation of La-clay mineral with impregnation is relatively simple, but the selection of appropriate carrier should be paid more attention. As shown in Table 5.2, the adsorption capacity of different types of clay minerals is not uniform after loading with lanthanum, and the specific surface area (SBET) and pore size distribution of different clay minerals are different (Ning et al. 2008; Li et al. 2009). 2. La-metallic compounds Normally, La-metallic compounds are synthetized with co-precipitation method. Lanthanum is co-precipitated with other metals, such as Fe or Al. The corresponding metal salts were selected and co-precipitation was achieved under suitable reaction conditions. 3. La-organics adsorbents In most cases, the acid treatment or alkali treatment is first subjected to the organic adsorbents for removing the remaining impurities and dredging channels. It is beneficial to the diffusion of lanthanum anions or particles. Lanthanum was modified or doped into the corresponding adsorbents by oxide-reduction reaction. Generally, the adsorbent, supporting the lanthanum, was first gained and then put into the solution containing lanthanum ions (La (NO)3 ∙ 6H2O as the precursor) for impregnating several hours. Then, the reducing agent (ammonia, sodium hydroxide, ammonium hydrogen carbonate) is added into mixed solution to generate the lanthanum oxide or hydrated lanthanum compound. The equation is as follows:

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179

La 3  OH   La  OH 3  La 2 O3  H 2 O

(5.1)

Lanthanum hydroxide loaded on adsorbent must be treated at high temperature to transform to lanthanum oxide as shown in Table 5.1 and Fig. 5.3. 5.2.1.2  Mechanism of Phosphorus Adsorption There is no doubt that the whole process of phosphate removal is dominated by adsorbents. From Table 5.2, we can see that adsorbents are almost found to better match with the pseudo-second-order model (R2 > 0.99) than the pseudo-first-order model, suggesting the adsorption process be chemisorption. It means that the phosphate ions in the solution undergo electron transfer or exchange with the lanthanum atoms or molecules modified in surface or interior of adsorbents. Meanwhile, The Langmuir model is more suitable for nanosized La-based adsorbents, which means that observed adsorption onto nanosized La-based adsorbents is caused by the monolayer coverage. The selective adsorption of the adsorbent is based on the property of adsorbent matrix and indirectly obtained by modification. Lanthanum is used to corresponding adsorbent for gaining better adsorption capacity of phosphate. The following reaction would be the mechanism responsible for the adsorption of phosphate by lanthanum (Xie et al. 2015; Huang et al. 2014a, b):

La  OH  HPO24   La  HPO 4  OH 

(5.2)



La  OH  H 2 PO 4  La  H 2 PO 4  OH 

(5.3)



La   OH 2  HPO24   La  HPO 4  2OH 



La   OH 3  PO34  La  PO 4  3OH 



(5.4) (5.5)

The mechanism might involve ion complexation during subsequent adsorption of phosphorus on lanthanum. It is showed that the ligand-exchange process at high pH levels on lanthanum (hydr) oxide surfaces. The diagram is shown in Fig. 5.3. Table 5.2 presented the most representative examples of the nanosized La-based adsorbents employed for the removal of phosphate from eutrophic water. From Table 5.2, under the same conditions, with the increase of lanthanum loading, the removal rate was obviously improved. It’s obvious that the greater amount of molar ratio of adsorbed P versus La (P/La), the higher the effective utilization of la active sites simultaneously. Furthermore, the adsorption of phosphate on most nano-materials fits the pseudo-second-order model, indicating that the phosphate adsorption process is likely governed by chemisorption. However, there are still some adsorbents in line with the pseudo-first-order kinetics. And the adsorption process was well described by the intraparticle diffusion model.

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Table 5.1  Comparison of preparation methods of materials Method calcination

Experiment process Mixture is stirred at 60 °C for 24 h and was calcined at 550 °C for 5 h Oxide-­ Calcination Reacting La(NO)3∙6H2O with NH4HCO3; dried at reduction 110 °C followed by calcination at 750 °C in a vacuum tube furnace for 6 h Electrospinning / Polyacrylonitrile and nano-La2O3 are dissolved in DMF (80 °C for 2 h); then electrospinning process (15 kV, 20 cm, 1.0 mL·h−1) /

References Huang et al. (2013) Chen et al. (2015a, b) He et al. (2016)

Fig. 5.3  Mechanism of material preparation and sketch map of phosphorus adsorption

5.2.2  I nfluence Factors of Phosphate Removal by Nanosized La-Based Adsorbents Based on the interaction between nanosized La-based adsorbents and phosphate, the adsorption process is significantly influenced by many factors including the pH, anions, organic acid, as well as the sorption conditions. 5.2.2.1  Effect of the P/La Value In this study, the dosage of adsorbents is replaced by the molar ratio of phosphorus to lanthanum (P/La) for more accurately reflecting the nature of the problem. In most cases, the removal efficiency (RE) increases as the molar ratio of P/La descends until it reaches a peak RE value, which generally remains constant even if the value of P/La is descended (Koilraj and Sasaki 2017). Under the low loading of lanthanum, the phosphate ions cannot be completely captured by the lanthanum for providing less active sites for phosphate adsorption. When the maximum adsorption capacity is obtained, the quantity of the particles is sufficient to interact with the phosphate.

/

/

50.00

La-clinoptilolite 4.01

/

La100SBA-15

LaAl-pillared clays

La(III)-modified / bentonite (NT-25La)

16.56

7.71

14

15.10

15.8

FMS-­0.10La

MWCNTsCOOH-La

La2O3/PAN nanofibers

Wheat straw-N-La

La-polystyrene networks

4.25

0.17

28.57

La40SBA-15

La-clay mineral

La-organics FMS-­0.02La

0.88

85.27

La2O3

/

/

1.99

0.36

1.04

1.16

1.18

1.17

/

La Content (Wt %) P/La

Adsorbent

Type

10.5

10.7

8.0

~5.0

/

/

/

/

/

/

pHpzc

4.88 (pore)

10 ~ 20

160 ~ 290

20 ~ 40

200 ~ 250

200 ~ 250

Less than 4 (pore)

1.98 (basal spacing)

18.65 (pore)

7.58 (pore)

7.87 (pore)

3 ~ 6

Size (nm)

24.42

87.8

/

140.0

102.6

278.3

115

13.6

227.0

326.0

12

94

14.0

9.72 42.76 48.02 10.89

[NT-25La] = 0.5 ~ 80 g·L−1; T = 25 °C; pH = 6.0 [P] = 50 mg·L−1; [FMS0.02La] = 1 g·L−1; T = 25 °C [P] = 50 mg·L−1; [FMS0.10La] = 1 g·L−1; T = 25 °C [P] = 50 mg·L−1; [MWCNTsCOOH-La] = 0.625 g/L; T = 25 °C [P] = 20 ~ 80 mg·L−1; [La2O3/PAN nanofibers] = 3.0 g·L−1; T = 25 °C

67.10 [P] = 5 ~ 80 mg·L−1; [wheat straw-N-La] = 0.5 g·L−1; T = 25 °C; pH = 6.2 /

28

8.90

[LaAl-pillared clays] = 25 g·L−1; T = 25 °C; pH = 5.0

/

99.45 Langmuir

1.49

[P] = 5 ~ 240 mg·L−1; [La-clinoptilolite] = 500 g·L−1; T = 25 °C; pH = 8.0

/

60

86

19

90

/

95

[P] = 10 ~ 80 mg·L−1; 45.63 [La100SBA-15] = 1 g·L−1; T = 25 °C

kinetic

References Xie et al. (2015)

PseudoTu et al. second-order (2016)

PseudoYang et al. second-order (2011)

PseudoYang et al. second-order (2011)

/

/

Langmuir

/

/

/

/

Langmuir

Qiu et al. (2017)

He et al. (2016)

Zong et al. (2017)

Huang et al. (2015a, b)

Huang et al. (2015a, b)

Kuroki et al. (2014)

(continued)

PseudoZhang et al. second-order (2016)

/

/

/

/

/

/

Freundlich Pseudo-first- Tian et al. order (2009)

Langmuir

Langmuir

40

20.08

/

[P] = 10 ~ 80 mg·L−1; [La40SBA-15] = 1 g·L−1; T = 25 °C

/

Model isotherm

46.95

SC (mg RE P∙g−1) (%)

/

SBET (m2∙g−1) Experimental conditions

Table 5.2  Nanosized La-based nanomaterials for phosphate removal

5  Nanomaterials for Effective Control of Algal Blooms in Water 181

16.71

La-MOF-500

/

La200-­silica foams (La200MOSF)

Fe3O4@SiO2-La 11.17

22.44

HMS-1/5

3D 62.8 graphene−La2O3

/

pHpzc

/

0.86

/

/

1.04

500 ~ 600

/

200 ~ 500

/

Size (nm)

10 ~ 40

3 ~ 10 /

4.4

5.0

/

0.936 /

La Content (Wt %) P/La

La(OH)3/porous carbon (La0.1-PC)

Adsorbent

47.73

172

420.38

28.3

308.9

27.80

47.89

[HMS-1/5] = 0.5 g·L−1; T = 25 °C; pH = 5.0

[P] = 0 ~ 200 mg·L−1; [Fe3O4@ SiO2-La] = 1 g·L−1; T = 25 °C

82.6

[3D graphene−La2O3] = 2 g·L−1; T = 25 °C; pH = 6.2

70.4

173.8

[P] = 40 ~ 100 mg·L−1; [La-MOF-500] = 0.2 g·L−1; T = 25 °C

/

12.52

99

/

/

/

/

/

SC (mg RE P∙g−1) (%)

/

SBET (m2∙g−1) Experimental conditions

a

Note: P/La Mole ratio of adsorbed Phosphate/La, SBET Specific surface area, RE Removal efficiency, SC Sorption capacity;

La-metallic compound

Type

Table 5.2 (continued)

Langmuir

/

Langmuir

/

Langmuir

Langmuir

Model isotherm Koilraj and Sasaki (2017)

References

/

Lai et al. (2016)

PseudoYang et al. second-order (2012)

PseudoHuang et al. second-order (2014a, b)

PseudoChen et al. second-order (2015a, b)

Pseudo Zhang et al. second-order (2017)

/

kinetic

182 R. Cheng et al.

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183

However, even with the greater loading of lanthanum, there is some inferior adsorption capacity for different adsorbents, as shown in Table 5.2. This is probably due to the great SBET and special pore size (Huang et al. 2014a, b; Tu et al. 2016). 5.2.2.2  Effect of pH Value Generally, the process of adsorption is deeply affected by pH of solution which influences state of the presence of substances in the solution and the surface charge of adsorbent. So, pH value is a very important parameter, affecting the removal efficiency of phosphorus in water by lanthanum modified adsorbent. Some studies have reported that the adsorption process of phosphate was strongly dependent on the pH value of solution (Zong et al. 2017; Huang et al. 2015a, b; Lai et  al. 2016). Figure  5.4b presents that the adsorption capacity of MWCNTs-­ COOH-­La changed very little within the pH range of 3.0 ~ 7.0. As pH reached 10.0, the adsorption capacity of MWCNTs-COOH-La (33.7 mg P g−1) was reduced by 22%, as compared with the value at pH 3.0 (43.1 mg P g−1) (Zong et al. 2017). The distribution of phosphate species e.g., H3PO4, H2PO4−, HPO42− and PO43−, in aqueous medium is highly dependent on the variation of pH value, which associates closely to the dissociation equilibrium constants of these phosphate species, such as pK1 = 2.12, pK2 = 7.21, and pK3 = 12.67 (Yang et al. 2014; Huang et al. 2014a, b).

Fig. 5.4  Effect of pH value on phosphate adsorption of La-MOF-500 (a), Fe3O4/SiO2-La (b) and La2O3-PAN fibers (c) and phosphate species of P (d) (Lai et al. 2016; Zhang et al. 2017)

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So, a higher pH value causes the adsorbents surface to carry more negative charges and thus would more significantly repulse the negatively charged species in solution. The increasing concentration of OH− in alkaline solution will greatly compete for the active sorption sites with phosphate ions, resulting in a significant decrease in phosphate adsorption and adsorption process was inhibited by precipitation of lanthanum (III) hydroxides (Suzuki et  al. 1989). On the other hand, the material would become negatively charged when solution pH is larger than the pHpzc (point of zero charge), which could have the same charge as phosphate ions. Thus, the Donnan co-ion exclusion or electrostatic repulsive forces would be dominated in adsorption, which is favorable for the loaded phosphate desorption. In addition, the monovalent phosphate anion, H2PO4−, has the greatest affinity for the adsorbent surface (Haghseresht et al. 2009). We can see that there are four different chemical forms in different range of pH value. According to Schroeder, the affinity of adsorbent for anions mainly depends on the anion’s valence and size (Schroeder 1984). The higher the valence and the smaller the hydrated ionic radius, the stronger is the adsorption. The increase in pH value during the adsorption process further confirms the ligand-exchange mechanism involved in the phosphate adsorption process. In the rough range of pH value (2.0 ~ 7.0), the lanthanum deposited on the adsorbents works as an active site, providing a great affinity to the monovalent phosphate species (H 2 PO −4 ) (the predominant phosphate species), which have a higher affinity for La (Wu et al. 2007). Moreover, with the rise of pH value, an additional advantage in treating wastewater without post-treatment pH adjustments is revealed (Koilraj and Sasaki 2017). Although the performance of La-based adsorbents has a decrease in condition of strong acids and alkalis, pH range (middle pH range) with high removal rate is the case of most wastewater or polluted natural water. However, as shown in Fig. 5.4c, d, the impact of pH values on both adsorbents assumes an opposite state of affairs. The possible reason is that different mechanisms which play a major role on whole reactions. 5.2.2.3  Effect of Coexisting Anions There is no doubt that the co-existing anions, such as F−, Cl−, NO3−, CO32− and SO2− 4 , which commonly occurring in natural waters or wastewater, are supposed to compete with phosphate ions for the active sites of adsorbents. So, the influences resulted by above anions are further evaluated by researches. In order to reflect the impact more clearly, the effects of various anions in many literatures are summarized in Table 5.3. With the increase of the concentration of coexisting anions, the adsorption of phosphorus decreased in different degrees. For example, the addition of foreign anions decreases the adsorption capacity of La100SBA-15 by 27%, 30%, 14%, 40% and 12% for F−, Cl−, NO3−, CO32− and SO2− 4 , respectively (Yang et al. 2011). In addition to carbonate ion, other particles would slightly retard the adsorption of phosphate.

27.8

37.20 40.25 45.77 46.95

La-silica

La-metallic

20.76 20.76 1.93

82.6

~57 82.6

La-clay minerals

Type La-organics

Co-ion free Uptake (mg P·g−1) ~140 11.6

[coexisting anion] = 20 mmol·L−1 Sorption capacity [coexisting anion] = 8 g·L−1 Removal efficiency Removal [P] = 142 mg·L−1; pH = 6.2; efficiency [coexisting anion] = 0.01 Mol·L−1 Sorption capacity [coexisting anion] = 0.1 Mol·L−1 Sorption capacity [coexisting anion] = 0.5 mmol·L−1 Removal efficiency Sorption capacity [coexisting anion] = 400 mg·L−1 [coexisting anion] = 0.01 Mol·L−1 Sorption capacity [coexisting anion] = 0.01 Mol·L−1 Sorption capacity [coexisting Sorption capacity aniontotal] = 0.1 Mol·L−1 Removal [coexisting efficiency aniontotal] = 0.01 Mol·L−1 /

27 30 No No ~1 ~1

14 1–2 ~12 7.1 1.3

No No No No No No 11.76 4.41

No 1–2 4.41

1.1

5.2

12 1–2 ~1

10.9

/

13.5

20.0

/

/

40 31.4 ~20

No 54.3

/

5.3

/ / /

No No 25.53

/

Lai et al. (2016)

Yang et al. (2011) Huang et al. (2015a, b) Huang et al. (2014a, b) Xie et al. (2015)

Huang et al. (2014a, b) Huang et al. (2014a, b) Tian et al. (2009)

Chen et al. (2015a, b)

SO42− CO32− HCO3− References No 13 / Zhang et al. (2017) No 31 / Koilraj and Sasaki (2017) ~20.7 ~24 / ~24.6 Zhang et al. (2016) 0 0 / / Chen et al. (2015a, b)

F− Cl− / No / No

26 0

Working conditions Type NO3− / Sorption capacity No [coexisting anion] = 20 mmol·L−1 Sorption capacity /

Decrease in the presence of coexisting anions (%)

Table 5.3  Comparison of the effect of phosphate adsorption capacities among the different anions

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From Table 5.3, we can see that the anion of CO32− has the largest influence on the phosphate adsorption capacity. Because the initial pH of the solution with CO32− is belong to alkaline, such as the pH of 0.1 mol·L−1 CO32− is 11.6 or so. Under above condition, a large amount of OH− is present, which competes with PO3− 4 for the adsorption active sites and hinders the ligand-exchange mechanism, thus lowering phosphate uptake more significantly (Huang et al. 2015a, b). Meanwhile, we can see that the concentration of carbonate (CO32− ) or bicarbonate (HCO3− ) ions has a great negative effect on the adsorption capacity. This was maybe attributed to the lower solubility product constant (Ksp) of La2 (CO3)3 (3.98 × 10−34) compared with that of LaPO4 (3.7  ×  10−23), which supported the alteration of the formed LaPO4 to La2(CO3)3 (Huang et al. 2014a, b). But there is a big difference in terms of HCO3– ions between this two references (Zhang et al. 2016; Tian et al. 2009). The possible reason is the effect of structure or zeta potential of material itself (Edzwald et al. 1976). If ion exchange played a significant role in the adsorption process, then the introduction of coexisting anions would have cut down the amount of phosphate adsorbed. Furthermore, the orders of the effect of various anions on the phosphate adsorption may be related with affinity of adsorbents toward anions (Schroeder 1984; Tian et al. 2009). 5.2.2.4  Effect of Temperature Temperature is an important parameter among several chemical and physical reactions. In nano-La typed adsorbents, the pore structure of matrix materials, even process of chemical adsorption is deeply affected by the temperature value. Large pore size of adsorbents contributes to the adsorption of P species (Yang et al. 2011). 5.2.2.5  Adsorption–Desorption Cycle In many studies, batch adsorption-desorption cycles are always carried out to investigate the repeated property of adsorbents. To a certain extent, desorption of P from La-adsorbents was difficult, for the forceful interaction between La sites and P. Typically, the means of regeneration are divided into alkali treatment and acid treatment. The phosphate–La compounds to give soluble La3+ and H3PO4 were gradually dissolved by acid treatment (0.5  M HCl). The reusability of fresh nano-La typed adsorbents mainly depends on the amount of PO43− ions desorbed from used sample. From the Table 5.4, unfortunately, we can see that the 90% of capacity of materials can still be maintained after the regeneration treatment, which indicates that the reusability of the materials is relatively satisfactory. In addition, the process of regeneration treatment will result in a caustic wastewater stream that contains high P, to which the calcium containing chemicals may be added into the alkaline wastewater stream for converting phosphate into calcium biphosphate, used as calcium phosphate fertilizer (Urano et al. 1992; Midorikawa et al. 2008). The remaining alkali solution could be neutralized by adding sulfuric acid before further reused

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Table 5.4  Regeneration methods and regeneration efficiency of materials Desorption Regeneration agent process NaOH NaOH-NaCl (10%–5%) solution La2O3 NaOH 12.5 M NaOH at 140 °C at a liquid and solid ratio of 6 mL·g−1 for a duration of 5 h La2O3 Oxalic acid 0.5 M oxalic acid at room temperature at a liquid/solid ratio of 80 mL·g−1 HMS-1/5 HCl 0.5 M HCl solution at room temperature at a liquid/solid ratio of 1 L·g−1 for 24 h La5EV NaOH 0.10 M NaOH solution for 48 h LaAl- pillared NaOH 0.1 M NaOH clays solution for 12 h La-vesuvianite HNO3 25 mL of 5% HNO3 with the used sample for 24 h (soaked and stirred) Fe3O4@ NaOH 3.0 M NaOH SiO2-La solution and 50 °C La-MOF-500 NaOH 300 mL 0.1 M NaOH for 4 h, then rinsed to pH =7 with DI water and dried La-MOF-500 Calcination 500 °C Adsorbent Wheat straw-N-La

Desorption Re-adsorption (%) (%) Cycles References 85 90 10 Qiu et al. (2017) 96.12

100

1

Xie et al. (2015)

98.75

100

1

Xie et al. (2015)

100

99

1

Huang et al. (2014a, b)

88.5

70

3

–

91–96

6

Huang et al. (2014a, b) Tian et al. (2009)

100

100

1

Li et al. (2009)

/

Lai et al. (2016)

95.1

/

18

/

Zhang et al. (2017)

/

34

/

Zhang et al. (2017)

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as desorption reagent for several times. Of course, for the environmental-friendly adsorbents (e.g. chitosan or clay, and so on), they can be used as a resource of fertilizer in agriculture directly. Overall, in spite of the promising future of the nano-La based materials in environmental technologies, there are some issues and challenges that need to be overcome before large scale development of the nano-La based materials. For example, these environmental factors (water flow, hydraulic pressure) should be given significant attention when considering the application of La modified adsorbents in eutrophication control; the biotoxicity of the material itself needs to be further studied; for non-recyclable adsorbents, the status about long-term desorption needs to be studied.

5.3  R  emoval of Harmful Algae by Nano-photocatalysts in Water All things are relative. When concentration of algal is at a normal level, the virtuous circulation of aquatic ecosystems is guaranteed, and the shades for hydrobiontes from the sunlight are also provided. However, the high concentration of algae will be disastrous, as their huge amount will exhaust the oxygen supply through respiration and releasing carbon dioxide during nighttime. Therefore, when algal blooms erupt, measures are taken. In general, mechanical salvage is universally adopted, but this method is time-consuming and laborious, and often does not achieve good results. In recent years, with the development of photocatalytic technology (simple and low cost), a new and effective solution to remove algae from eutrophication water is provided.

5.3.1  Nano-photocatalysts In the photocatalytic catalyst for algae removal, nano TiO2 has been widely studied because of its chemical stability, non-toxic, low cost and high photocatalytic activity. Meanwhile, other types of nano-photocatalysts have emerged, such as ZnO, AgBiO3, and so forth. But in practice, photocatalysts also have their own defects. Firstly, high recombination rate of electrons and holes produced by light and low quantum efficiency, both greatly reduce the photocatalytic activity. Secondly, TiO2 has wide bandgap. Theoretically, only ultraviolet light can stimulate valence band electrons to transition to conduction band. And the ultraviolet light accounts for only 4% of the solar radiation, so the utility rate of the sunlight is low, and the artificial ultraviolet light is relatively expensive and the use range is also limited. From the Table 5.5, the removal of algae by nano-photocatalysts reached 90% within 2  h under UV light. However, the removal efficiency under visible light needs to be improved in the future.

60 min

9 h

150 min

96 h

7–14 nm

7–14 nm

5–10 nm

30 nm

50 nm

0.75 nm

~500 nm

Materials Montmorillonite/ (CuO + Fe2O3) Ag-TiO2

Ag-TiO2

Cu2O-montmorillonite

ZnO–montmorillonite

N,P doped TiO2/graphite carbon layer Zn–Fe LDHs

AgBiO3

60 min

180 min

40 min

Contact time 20 min

Particle Size /

M. aeruginosa M. aeruginosa M. aeruginosa M. aeruginosa M. aeruginosa

T. suecica

Algae M. aeruginosa A. carterae

Table 5.5  Performance of nano-photocatalyst for removing algae

~1.0 × 106

2.8 × 105

2.7 × 106

2.8 × 105

2.8 × 107

(2.5 ± 0.2) × 105

(1 ± 0.1) × 105

initial concentration (cells·mL−1) 53 mg·L−1

100%

99%

Removal rate 94.8%

98.15%

95%

/

65.69%

Visible light, 250 mg·L−1, 80.6%

UVλ = 365 nm, 300 W, 50 mg·L−1, λ > 380 nm

Visible light, 400 mg·L−1, 90.4%

UV, 40 W,

UV, 40 W,

Working conditions pH = 6.8, 1 g·L−1,

Yu et al. (2010)

Gu et al. (2016a, b)

Wang et al. (2017)

Gu et al. (2015)

Rodríguez-González et al. (2010) Rodríguez-González et al. (2010) Gu et al. (2016a, b)

References Gao et al. (2009)

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5.3.2  Mechanism of Photocatalytic Removal of Algae The principle of photocatalysis lies in the production of many free radicals, which have the effect of killing algae. As shown below.

pholocatalyst  h  e   h 

(5.6)



OH   h   OH

(5.7)



 2



O2  e  O

(5.8)



 O2  h   HO2 

(5.9)



HO2   HO2   H 2O2  O2

(5.10)



H 2 O2  e   OH    OH

(5.11)



H 2 O2   O2  OH    OH  O2

(5.12)

When the energy of light irradiated to the surface of the catalyst is higher than the band gap (Eg) of the semiconductor, the electrons in the semiconductor will be excited to move from the valence band to the conduction band. An electron-hole pair with strong activity is formed and further induces a series of redox reactions (6–12).

Fig. 5.5  Schematic of the possible reaction mechanism of the photocatalyst (from (Wang et al. 2017))

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From Fig. 5.5, we can see that the algae was destructed by the radicals (·OH, h+ and ·O2− and so on) produced by photocatalyst and the process can be divided into three steps: first, cell walls and membranes were destroyed (The ROS can cause irreversible damage to the membrane protein, which results in electrolyte leaking; after which, the conductivity of the solution increases); Then, the photosynthetic system was damaged; Finally, degradation of the metabolic products was achieved by photocatalyst (Yu et al. 2010).

5.4  Removal of Microcystins in Water Algae bloom due to eutrophication in aquatic environments and associated microcystins contamination are increasingly reported worldwide (Carmichael et al. 2001). The adverse effects of cyanobacterial toxins were first reported as stock deaths at Lake Alexandrina, South Australia, in 1878. Since then, poisoning incidents of microcystins in animals and humans have been widely reported around the world. Microcystins can be accumulated in aquatic organisms and transferred to higher trophic levels through the food chain, representing a health hazard to animals and humans (Chen et al. 2016; Florczyk et al. 2014). Algal toxins are mainly produced from cyanobacteria, including microcystins (MCs), neurotoxins, nodularins, hepatotoxins, anatoxins alpha, paralytic shellfish poisoning, and so on. At present, the research targets of algae toxins mainly focus on microcystins. MC belongs to the cyclic seven peptide of liver toxins and has many isomers, among which the most common are MC-LR, MC-RR, MC-YR (L, R, Y as leucine, arginine and tyrosine respectively). Until now, nearly 90 variants of microcystins have been discovered (Zhang et al. 2010). MC-LR (LD50 = 50 g·kg−1) exhibits higher lethality than the venom of dangerous snakes such as cobra (LD50 = 500 g·kg−1) (Richardson 2007). In addition, MCs are extremely stable and resistant to chemical hydrolysis or oxidation at nearly neutral pH values, and they may persist for months or even years in natural water. When MC-LR enters the human body, it can produce a large number of hepatic toxins in a short time, and inhibit the production of protein phosphatase, thus causing tumor lesions (Wiegand and Pflugmacher 2005). Because cyanobacterial toxins have hepatotoxicity, neurotoxicity, genotoxicity, embryonic toxicity, and carcinogenicity, the residual algal toxins in drinking water can cause serious health risks to humans (Meneely and Elliott 2013; Fang 2013). The limiting concentration for algal toxins in drinking water is less than 1.0 ug·L−1 in China and World Health Organization. The maximum possible length of the MC-LR molecule is 2.94 nm (Sathishkumar et  al. 2010a, b). MC-LR contains five nonproteinogens and two substitutions of leucine (L) and arginine (R) at positions 2 and 4, which is the most toxic species, as shown in Fig. 5.6. In these microcystins, the MC-LR is the most common and toxic variant of the group of microcystins (MCs) produced during the formation of harmful

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Fig. 5.6  Structure diagram of MC-LR

cyanobacterial blooms. In this paper, therefore, a brief summary on the current nanotechnologies of dealing with MC-LR is made to provide some guidance.

5.4.1  Doped TiO2 Nano-pholocatalyst As we all know, photocatalytic materials have been extensively studied in recent years and have great prospects on degradation of organic pollutant, including phenolic, chlorine, antibiotic and so forth (Grabowska et  al. 2012). Similarly, MCs belong to organic macromolecules and could be degraded by photocatalysis (Triantis et al. 2012). Although TiO2 has a high photocatalytic activity under UV light, its limited photocatalytic activity in visible light is still one of its main drawbacks. Therefore, it is of great interest to find a way to extend the absorption wavelength range of TiO2 to the visible region. Actually, a huge emphasis has been put all over the world to generate a visible light active TiO2. But conventional TiO2 photocatalyst can only utilize the light with wavelengths shorter than 388 nm (UV range) due to its wide band gap (e.g. Eg ≈ 3.2 eV for anatase). These elements (C, N, S, F) utilized as dopants to narrow the band gap or form intra band gap of TiO2 materials and decrease the required activation energy (Barolo et  al. 2012). For example, N doping can achieve band gap narrowing through substitution lattice sites by mixing of N2p with O2p states in the valence band (Asahi et al. 2001). In the case of sulfur doping, sulfur substitutes either the oxygen as an anion or the titanium as cations. The overlap of sulfur 3p states and oxygen 2p states facilitates the visible light catalytic activity of S-doped TiO2. For low concentration of carbon doping, Di Valentin et  al. have reported that carbon atoms prefer to be interstitial and substitutional to Ti atoms under oxygen-rich conditions, whereas prefer to be substitutional to O under anoxic conditions (Tachikawa et al. 2004, Di Valentin et al. 2005).

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Table 5.6  Parameters and removal rates of MC-LR from different doped TiO2 SBET Adsorbent Wavelengths (m2∙g−1) Working condition P25 320 ~ 400 nm / [MC-LR] = 10 mg·L−1; dose = 200 mg·L−1; irradiation = 10 min; P25 >420 nm / [MC-LR] = 0.5 ug·L−1; dose = 500 mg·L−1; irradiation = 5 h; C doped / 103 [MC-LR] = 500 μg·L−1; TiO2 1 h; 7.81 × 10−5 W· cm−2; pH = 5.7 C doped 410 ~ 420 nm / [MC-LR] = 2 g·L−1; TiO2 dose = 200 g·L−1; irradiation = 5 h; N doped Solar / [MC-LR] = 10 mg·L−1; TiO2 irradiation dose = 450 mg·L−1; irradiation = 4 h; S doped / 179 / TiO2 S doped >420 nm [MC-LR] = 500 μg·L−1; TiO2 dose = 200 mg·L−1; irradiation = 5 h; N-F / 136 / doped TiO2 S-N-C / 85.1 / doped TiO2 S-N-C / 135.9 Visible light doped TiO2

Removal 100%

References Fotiou et al. (2015)

12.2%

El-Sheikh et al. (2014)

550.0 μg·g−1

Likodimos et al. (2013)

55%

Fotiou et al. (2016)

100%

Fotiou et al. (2015)

630.4 μg·g−1

Likodimos et al. (2013) Changseok et al. (2011)

60%

187.5 μg·g−1

Likodimos et al. (2013)

100%

El-Sheikh et al. (2014)

75% in 5 h

Zhang et al. (2014)

For example, Likodimos et al. reported that the band gap (~3.2 eV) of anatase TiO2 phase achieved a marked decline (2.9, 2.8 and 2.7 eV) by doping the non-metal elements (N-F, S and C) respectively (Likodimos et al. 2013). From the Table 5.6, we can see that with the doping of elements, the photocatalytic properties of the materials are improved under visible light. There are three reasons for the high photodegradation rate of doped-TiO2. First, the high adsorption rate of doped-TiO2 results in a higher photocatalytic potential. Second, electrons could be promoted from the VB to the CB more easily, resulting in the formation of energized holes on the surface of the TiO2. Third, doped elements can impede electron–hole recombination and enhance the efficacy of photocatalytic degradation. With the element doped, this behavior could be ascribed to a red-shift of the energy band gap to the visible range lower than 3.2 eV, justifying visible light photocatalytic activity during MC-LR degradation (El-Sheikh et al. 2014; Pelaez et al. 2016).

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5.4.2  Photodegradation Mechanism of Photocatalyst Photocatalyst produces electron transition under light condition, forming holes and electrons, and then producing a lot of free radical groups to oxidize and degrade pollutants. Through the analysis of free radicals, the main action of free radicals was obtained, and the intermediate products were analyzed by Mass Spectrometric analysis, and the mechanism of degradation was obtained in detail as shown in Fig. 5.7. It has been determined that degradation of MC-LR occurs at four sites of the structure: the aromatic ring, the methoxy group, conjugated double bond of the Adda group and the cyclic structure of the Mdha amino acid (Antoniou et al. 2008). In general, The proposed pathways of photocatalytic degradation of MC-LR indicated that the conjugated double bond and methoxy group in Adda, and the conjugated system in Mdha are liable to be attacked by •OH (Su et al. 2013). As shown in Fig. 5.7, the conjugated carbon double bonds of Adda were attacked by hydroxyl radicals presented by photocatalyst (pink area) and converted to HO-C-OH structure and further oxidation. The formed aromatic ring and double bonds will be further oxidized to another substance or directly mineralized. After breakdown of the conjugated system in Mdha, the carboxyl group and amino group of the peptides are hydrolyzed. Subsequently, the side chain of the amino acid could be oxidized and mineralized. The Adda chain is deduced to be destroyed and separated from the heptapeptides to produce alkyl derivatives (Wu et al. 2017a, b).

Fig. 5.7  Brief diagram of degradation pathway of MC-LR by photocatalyst

Adsorbents Fe3O4@nSiO2@mSiO2 microspheres Mesoporous carbons PPy/Fe3O4 Carbon nanotubes Graphene oxide Peat γ-Fe2O3 N-doped carbon xerogel Mesoporous carbons Rattle-type magnetic carbon shell Mpg-C3N4–H+ Porous activated semi-cokes

Particle Size 200 nm 4.5 × 1.9 mm 50–100 nm 2–60 nm 1.0 nm / 10–30 nm / / ~600 nm / /

Pore size 2.3 nm 2.8 to 5.8 nm / / / 1–13.3 nm / 4.1 nm 8.5–14 nm 2.7 nm 14.68 nm 2–20 nm

Contact time 5.0 min 4 h 10 min 8 h 5 min 30 min 48 h 30 min / 5 min 15 min 24 h

Table 5.7  Comparison of adsorption capacities of MC-LR with different adsorbents pH 7.0 / 7.0 7.0 5.0 3.0 4.4 / / 7.0 7.0 /

Adsorption capacity 160 mg·g−1 526 mg·g−1 301.11 mg·g−1 14.8 mg·g−1 1.69 mg·g−1 0.286 mg·g−1 2.7264 mg·g−1 1.9162 mg·g−1 35.67 mg·g−1 166.67 mg·g−1 2.361 mg·g−1 8.43 mg·g−1

Model / Langmuir Langmuir / Langmuir Langmuir / Langmuir Langmuir / Langmuir Langmuir

References Deng et al. (2008) Teng et al. (2013) Hena et al. (2016) Yan et al. (2006) Pavagadhi et al. (2013) Sathishkumar et al. (2010a, b) Lee and Walker (2011) Wu et al. (2017a, b) Park et al. (2017) Zhang and Jiang (2011) Huang et al. (2015a, b) Chen et al. (2015a, b)

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Fig. 5.8  Adsorption model illustration of MC-LR molecules on nano-adsorbents

5.4.3  Nanosized Adsorbents After many depth studies, it was found that the pore size of the adsorbent was associated with the size of the microcystin. The largest volume of mesopores (pore diameter in the range of 2 ~ 50 nm) were shown to be the most efficient as shown in the Table 5.7 (Donati et al. 1994). From the Table 5.7, we can obviously see that the adsorption model is basically consistent with Langmuir and the pore size is mainly between 2 and 50 nm for the adsorbent with high adsorption capacity (Fig. 5.8). In addition, MC-LR molecules, with several carbonyl and carboxyl groups, also have a strong affinity toward the metals (Xia et al. 2013; Vimont et al. 2006).

5.4.4  Other Combined Means Other scholars have combined the advantages of adsorption and degradation technology. For example, Wei et al. have synthesized carbon-nanotube-based sandwich-­ like hollow fiber membranes, which present three layer structure, the outer layer is a carbon nanotube, and the center is PVDF (40–60 nm CNT layer-PVDF-60-100 nm CNT layer). The removal of MC-LR is achieved by accessing the voltage of the 2 ~ 3 V (Wei et al. 2017). A marked effect has been achieved by Combining ultrafiltration (UF) membrane combined with coagulation and flocculation and powdered activated carbon for removing intra- and extracellular microcystin (Şengül et al. 2018). The functional bentonite supported Fe/Pd nanoparticles (B-Fe/Pd) was used to remove microcystin-LR (MC-LR) and the batch experiments showed that 96.86% of MC-LR was removed using B-Fe/Pd, while only 81.76% and 10.06% of MC-LR were removed using Fe/Pd nanoparticles and bentonite after degrading 3 h (Wang et al. 2014).

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5.5  Conclusions In summary, with the development of nanotechnology, more and more various types of nanomaterials are have been designed, synthesized and employed into eutrophication bodies, which have been well treated and repaired. In this review, the application of nanomaterials was described from phosphorus removal, algae blooms removal, and Microcystin-LR removal, respectively. The advances of nanomaterials lie in their large specific surface areas, which facilitate the provision of more active sites and enhance their ability to remove pollutants. In terms of the removal of P from eutrophication, the main means of participation of nanotechnology is adsorbent. In this paper, La-based nano-adsorbent are summarized. In the nanometer field, the adsorption technology occupies the main position because of its feasibility and simplicity. Additionally, for the removal of algae cell from the water, means of nanomaterials consists of adsorption and inactivation. However, what is disturbing is that when the cells are broken, the intracellular algae toxins would release into the water to increase the concentration of algal toxins in the water, which results in bigger problem. So, the current technologies focus on the strong adsorption capacity for adsorbents with nanostructure (size or pore) or degradation of both cells and intracellular pollutant such as nano-photocatalyst (TiO2, ZnO, MoS, g-C3N4, and so on.). For removal of algal toxin from water, more and more scholars are concerned about something that can be completely harmless, such as photocatalysis, Fenton-­ like reaction and so on. And in recent years, photocatalytic technology has been developed continually because of its high reaction activity, mild reaction condition and high mineralization rate. However, in view of the shortcomings of existing catalysts such as high carrier recombination rate and narrow range of photo response, it is of importance to select and optimize the catalyst. Overall, nanomaterials play an important role in algae bloom. Besides, scale-up studies are put on the agenda before these methods are considered as economically feasible and practical sustainable alternatives in algae bloom control. Moreover, the current practical applications of nanomaterials will promote the birth of more highly efficient nanomaterials with unexpected performances, by which beauty of the world environment will be made. Acknowledgments  This work was supported by the National Natural Science Foundation of China (Grant No. 51778618), which is greatly acknowledged.

References Antoniou MG, Shoemaker JA, de la Cruz AA, Dionysiou DD (2008) LC/MS/MS structure elucidation of reaction intermediates formed during the TiO2 photocatalysis of microcystin­LR. Toxicon 51(6):1103–1118. https://doi.org/10.1016/j.toxicon.2008.01.018

198

R. Cheng et al.

Asahi R, Morikawa T, Ohwaki T, Aoki K, Taga Y (2001) Visible-light photocatalysis in nitrogen-­ doped titanium oxides. Science 293(5528):269–271. https://doi.org/10.1126/science.1061051 Barolo G, Livraghi S, Chiesa M, Paganini MC, Giamello E (2012) Mechanism of the Photoactivity under visible light of N-doped titanium dioxide. Charge carriers migration in irradiated N-TiO2 investigated by Electron paramagnetic resonance. J Phys Chem C 116(39):20887–20894. https://doi.org/10.1021/jp306123d Barrado-Moreno MM, Beltrán-Heredia J, Martín-Gallardo J (2017) Degradation of microalgae from freshwater by UV radiation. J Ind Eng Chem 48:1–4. https://doi.org/10.1016/j. jiec.2016.12.030 Carmichael WW, Azevedo SM, An JS, Molica RJ, Jochimsen EM, Lau S, Rinehart KL, Shaw GR, Eaglesham GK (2001) Human fatalities from cyanobacteria: chemical and biological evidence for cyanotoxins. Environ Health Perspect 109(7):663–668 Changseok H, Miguel P, Vlassis L, Kontos AG, Polycarpos F (2011) Innovative visible light-­ activated sulfur doped Ti02 films for water treatment. Appl Catal B Environ 107:77–87. https:// doi.org/10.1016/j.apcatb.2011.06.039 Chen M, Huo C, Li Y, Wang J (2015a) Selective adsorption and efficient removal of phosphate from aqueous medium with graphene-lanthanum composite. ACS Sustain Chem Eng 4(3):1296–1302. https://doi.org/10.1021/acssuschemeng.5b01324 Chen Y, Zhang X, Liu Q, Wang X, Xu L (2015b) Facile and economical synthesis of porous activated semi-cokes for highly efficient and fast removal of microcystin-LR. J Hazard Mater 299:325–332. https://doi.org/10.1016/j.jhazmat.2015.06.049 Chen L, Chen J, Zhang X, Xie P (2016) A review of reproductive toxicity of microcystins. J Hazard Mater 301:381–399. https://doi.org/10.1016/j.jhazmat.2015.08.041 Chouyyok W, Wiacek RJ, Pattamakomsan K, Sangvanich T, Grudzien RM, Fryxell GE, Yantasee W (2010) Phosphate removal by anion binding on functionalized Nanoporous sorbents. Environ Sci Technol 44(8):3073–3078. https://doi.org/10.1021/es100787m Copetti D, Finsterle K, Marziali L, Stefani F, Tartari G, Douglas G, Reitzel K, Spears BM, Winfield IJ, Crosa G, D’Haese P, Yasseri S, Lürling M (2016) Eutrophication management in surface waters using lanthanum modified bentonite: a review. Water Res 97:162–174. https://doi. org/10.1016/j.watres.2015.11.056 Delaney P, Mcmanamon C, Hanrahan JP, Copley MP, Holmes JD (2011) Development of chemically engineered porous metal oxides for phosphate removal. J Hazard Mater 185:382–391. https://doi.org/10.1016/j.jhazmat.2010.08.128 Deng Y, Qi D, Deng C, Zhang X, Zhao D (2008) Superparamagnetic high-magnetization microspheres with an Fe3O4@SiO2 Core and perpendicularly aligned mesoporous SiO2 Shell for removal of microcystins. J Am Chem Soc 130(1):28–29. https://doi.org/10.1021/ja0777584 Di Valentin C, Pacchioni G, Selloni A (2005) Theory of carbon doping of titanium dioxide. Chem Mater 17(26):6656–6665. https://doi.org/10.1021/cm051921h Donati C, Drikas M, Hayes R, Newcombe G (1994) Microcystin-LR adsorption by powdered activated carbon. Water Res 28(8):1735–1742 Edzwald JK, Toensing DC, Leung CY (1976) Phosphate adsorption reactions with clay minerals. Environ Sci Technol 10(5):485–490. https://doi.org/10.1021/es60116a001 El-Sheikh SM, Zhang G, El-Hosainy HM, Ismail AA, O’Shea KE, Falaras P, Kontos AG, Dionysiou DD (2014) High performance sulfur, nitrogen and carbon doped mesoporous anatase-brookite TiO2 photocatalyst for the removal of microcystin-LR under visible light irradiation. J Hazard Mater 280:723–733. https://doi.org/10.1016/j.jhazmat.2014.08.038 Epe TS, Finsterle K, Yasseri S (2017) Nine years of phosphorus management with lanthanum modified bentonite (Phoslock) in a eutrophic, shallow swimming lake in Germany. Lake Reservoir Manag 33(2):119–129 Fang D (2013) Nodularins in poisoning. Clin Chim Acta 425:18–29. https://doi.org/10.1016/j. cca.2013.07.005 Florczyk M, Łakomiak A, Woźny M, Brzuzan P (2014) Neurotoxicity of cyanobacterial toxins. Environ Biotechnol 10(1):26–43. https://doi.org/10.14799/ebms246

5  Nanomaterials for Effective Control of Algal Blooms in Water

199

Fotiou T, Triantis TM, Kaloudis T, Hiskia A (2015) Evaluation of the photocatalytic activity of TiO2 based catalysts for the degradation and mineralization of cyanobacterial toxins and water off-odor compounds under UV-A, solar and visible light. Chem Eng J 261:17–26. https://doi. org/10.1016/j.cej.2014.03.095 Fotiou T, Triantis TM, Kaloudis T, O’Shea KE, Dionysiou DD, Hiskia A (2016) Assessment of the roles of reactive oxygen species in the UV and visible light photocatalytic degradation of cyanotoxins and water taste and odor compounds using C–TiO2. Water Res 90:52–61. https:// doi.org/10.1016/j.watres.2015.12.006 Gao Z, Penga X, Zhang H, Luan Z, Fan B (2009) Montmorillonite–Cu(II)/Fe(III) oxides magnetic material for removal of cyanobacterial Microcystis aeruginosa and its regeneration. Desalination 247:337–345. https://doi.org/10.1016/j.desal.2008.10.006 Grabowska E, Reszczyńska J, Zaleska A (2012) Mechanism of phenol photodegradation in the presence of pure and modified-TiO2: a review. Water Res 46(17):5453–5471. https://doi. org/10.1016/j.watres.2012.07.048 Gu N, Gao J, Wang K, Yang X, Dong W (2015) ZnO–montmorillonite as Photocatalyst and Flocculant for inhibition of cyanobacterial bloom. Water Air Soil Pollut 226:136. https://doi. org/10.1007/s11270-­015-­2407-­5 Gu N, Gao J, Li H, Wu Y, Ma Y, Wang K (2016a) Montmorillonite-supported with Cu2O nanoparticles for damage and removal of Microcystis aeruginosa under visible light. Appl Clay Sci 132–133:79–89 Gu N, Gao J, Wang K, Li B, Dong W, Ma Y (2016b) Microcystis aeruginosa inhibition by Zn–Fe– LDHs as photocatalyst under visible light. J Taiwan Inst Chem Eng 64:189–195. https://doi. org/10.1016/j.jtice.2016.04.016 Haghseresht F, Wang S, Do DD (2009) A novel lanthanum-modified bentonite, Phoslock, for phosphate removal from wastewaters. Appl Clay Sci 46(4):369–375. https://doi.org/10.1016/j. clay.2009.09.009 Hartmann NB, Von der Kammer F, Hofmann T, Baalousha M, Ottofuelling S, Baun A (2010) Algal testing of titanium dioxide nanoparticles—testing considerations, inhibitory effects and modification of cadmium bioavailability. Toxicology 269(2–3):190–197. https://doi.org/10.1016/j. tox.2009.08.008 He J, Wang W, Shi W, Cui F (2016) La2O3 nanoparticle/polyacrylonitrile nanofibers for bacterial inactivation based on phosphate control. RSC Adv 6(101):99353–99360. https://doi. org/10.1039/C6RA22374E Hena S, Rozi R, Tabassum S, Huda A (2016) Simultaneous removal of potent cyanotoxins from water using magnetophoretic nanoparticle of polypyrrole: adsorption kinetic and isotherm study. Environ Sci Pollut R 23(15):14868–14880. https://doi.org/10.1007/s11356-­016-­6540-­5 Huang W, Li D, Yang J, Liu Z, Zhu Y, Tao Q, Xu K, Li J, Zhang Y (2013) One-pot synthesis of Fe(III)-coordinated diamino-functionalized mesoporous silica: effect of functionalization degrees on structures and phosphate adsorption. Microporous Mesoporous Mater 170:200–210. https://doi.org/10.1016/j.micromeso.2012.10.027 Huang W, Li D, Liu Z, Tao Q, Zhu Y, Yang J, Zhang Y (2014a) Kinetics, isotherm, thermodynamic, and adsorption mechanism studies of La(OH)3-modified exfoliated vermiculites as highly efficient phosphate adsorbents. Chem Eng J 236:191–201. https://doi.org/10.1016/j. cej.2013.09.077 Huang W, Zhu Y, Tang J, Yu X, Wang X (2014b) Lanthanum-doped ordered mesoporous hollow silica spheres as novel adsorbents for efficient phosphate removal. J Mater Chem A 2:8839–8848. https://doi.org/10.1039/c4ta00326h Huang C, Zhang W, Yan Z, Gao J, Liu W (2015a) Protonated mesoporous graphitic carbon nitride for rapid and highly efficient removal of microcystins. RSC Adv 5:45368–45375. https://doi. org/10.1039/c5ra01415h Huang W, Yu X, Tang J, Zhu Y, Zhang Y, Li D (2015b) Enhanced adsorption of phosphate by flower-like mesoporous silica spheres loaded with lanthanum. Microporous Mesoporous Mater 217:225–232. https://doi.org/10.1016/j.micromeso.2015.06.031

200

R. Cheng et al.

Huang W, Zhang Y, Li D (2017) Adsorptive removal of phosphate from water using mesoporous materials: A review. J Environ Manag 193:470–482. https://doi.org/10.1016/j. jenvman.2017.02.030 Kasp L, Jona N, Fred N, Kjel N, Henn N (2005) Lake restoration by dosing phosphorus in the sediment. Environ Sci Technol 39:4134–4140. https://doi.org/10.1021/es0485964 Koilraj P, Sasaki K (2017) Selective removal of phosphate using La-porous carbon composites from aqueous solutions: batch and column studies. Chem Eng J 317:1059–1068. https://doi. org/10.1016/j.cej.2017.02.075 Kuroki V, Bosco GE, Fadini PS, Mozeto AA, Cestari AR (2014) Use of a La(III)-modified bentonite for effective phosphate removal from aqueous media. J Hazard Mater 274:124–131. https:// doi.org/10.1016/j.jhazmat.2014.03.023 Lai L, Xie Q, Chi L, Gu W, Wu D (2016) Adsorption of phosphate from water by easily separable Fe3O4 @SiO2 core/shell magnetic nanoparticles functionalized with hydrous lanthanum oxide. J Colloid Interface Sci 465:76–82. https://doi.org/10.1016/j.jcis.2015.11.043 Lee J, Walker HW (2011) Adsorption of microcystin-Lr onto iron oxide nanoparticles. Colloids Surf A Physicochem Eng Asp 373(1–3):94–100. https://doi.org/10.1016/j.colsurfa.2010.10.032 Li H, Ru JY, Yin W, Liu XH, Wang JQ (2009) Removal of phosphate from polluted water by lanthanum doped vesuvianite. J Hazard Mater 168:326–330. https://doi.org/10.1016/j. jhazmat.2009.02.025 Li D, Min H, Jiang X, Ran X, Zou L (2013) One-pot synthesis of aluminum-containing ordered mesoporous silica MCM-41 using coal fly ash for phosphate adsorption. J Colloid Interface Sci 404(32):42–48. https://doi.org/10.1016/j.jcis.2013.04.018 Likodimos V, Han C, Pelaez M, Kontos AG, Liu G, Zhu D, Liao S, de la Cruz AA, O’Shea K, Dunlop PSM, Byrne JA, Dionysiou DD, Falaras P (2013) Anion-doped TiO2 Nanocatalysts for water purification under visible light. Ind Eng Chem Res 52(39):13957–13964. https://doi. org/10.1021/ie3034575 Liu S, Li J, Yang Y, Wang J, Ding H (2016) Influence of environmental factors on the phosphorus adsorption of lanthanum-modified bentonite in eutrophic water and sediment. Environ Sci Pollut R 23:2487–2494. https://doi.org/10.1007/s11356-­015-­5453-­z Lu SG, Bai SQ, Zhu L, Shan HD (2009) Removal mechanism of phosphate from aqueous solution by fly ash. J Hazard Mater 161(1):95–101. https://doi.org/10.1016/j.jhazmat.2008.02.123 Lürling M, Waajen G, van Oosterhout F (2014) Humic substances interfere with phosphate removal by lanthanum modified clay in controlling eutrophication. Water Res 54:78–88. https://doi. org/10.1016/j.watres.2014.01.059 Melnyk PB (1974) Precipitation of phosphates in sewage with lanthanum: an experimental and modelling study. In: Norman JD, Doctoral dissertation, Canada Research. http://hdl.handle. net/11375/14316 Meneely JP, Elliott CT (2013) Microcystins: measuring human exposure and the impact on human health. Biomarkers 18(8):639–649. https://doi.org/10.3109/1354750X.2013.841756 Midorikawa I, Aoki H, Omori A, Shimizu T, Kawaguchi Y, Kassai K, Murakami T (2008) Recovery of high purity phosphorus from municipal wastewater secondary effluent by a high-­ speed adsorbent. Water Sci Technol J Int Assoc Water Pollut Res 58(8):1601–1607. https://doi. org/10.2166/wst.2008.537 Ning P, Bart HJ, Li B, Lu X, Zhang Y (2008) Phosphate removal from wastewater by model-­ La(III) zeolite adsorbents. J Environ Sci (China) 20(6):670–674 O’Neil JM, Davis TW, Burford MA, Gobler CJ (2012) The rise of harmful cyanobacteria blooms: the potential roles of eutrophication and climate change. Harmful Algae 14:313–334. https:// doi.org/10.1016/j.hal.2011.10.027 Park JA, Jung SM, Yi IG, Choi JW, Kim SB (2017) Adsorption of microcystin-LR on mesoporous carbons and its potential use in drinking water source. Chemosphere 177:15–23. https://doi. org/10.1016/j.chemosphere.2017.02.150 Pavagadhi S, Tang ALL, Sathishkumar M, Loh KP, Balasubramanian R (2013) Removal of microcystin-­LR and microcystin-RR by graphene oxide: adsorption and kinetic experiments. Water Res 47(13):4621–4629. https://doi.org/10.1016/j.watres.2013.04.033

5  Nanomaterials for Effective Control of Algal Blooms in Water

201

Pelaez M, Falaras P, Likodimos V, O’Shea K, de la Cruz AA, Dunlop PSM, Byrne JA, Dionysiou DD (2016) Use of selected scavengers for the determination of NF-TiO2 reactive oxygen species during the degradation of microcystin-LR under visible light irradiation. J Mol Catal A Chem 425:183–189. https://doi.org/10.1016/j.molcata.2016.09.035 Pieterse NM, Bleuten W, Rgensen SJ (2003) Contribution of point sources and diffuse sources to nitrogen and phosphorus loads in lowland river tributaries. J Hydrol 271:213–225 Qiu H, Liang C, Yu J, Zhang Q, Song M, Chen F (2017) Preferable phosphate sequestration by nano-La(III) (hydr)oxides modified wheat straw with excellent properties in regeneration. Chem Eng J 315:345–354. https://doi.org/10.1016/j.cej.2017.01.043 Richardson SD (2007) Water analysis: emerging contaminants and current issues. Anal Chem 79(12):4295–4324. https://doi.org/10.1021/ac070719q Rodríguez-González V, Alfaro SO, Torres-Martínez LM, Cho S, Lee S (2010) Silver–TiO2 nanocomposites: synthesis and harmful algae bloom UV-Photoelimination. Appl Catal B Environ 98(3–4):229–234. https://doi.org/10.1016/j.apcatb.2010.06.001 Saha B, Chakraborty S, Das G (2009) A mechanistic insight into enhanced and selective phosphate adsorption on a coated carboxylated surface. J Colloid Interface Sci 331:21–26. https://doi. org/10.1016/j.jcis.2008.11.007 Sathishkumar M, Pavagadhi S, Mahadevan A, Balasubramanian R, Burger DF (2010a) Removal of a potent cyanobacterial hepatotoxin by peat. J Environ Sci Health A 45(14):1877–1884. https:// doi.org/10.1080/10934529.2010.520598 Sathishkumar M, Pavagadhi S, Vijayaraghavan K, Balasubramanian R, Ong SL (2010b) Experimental studies on removal of microcystin-LR by peat. J Hazard Mater 184(1–3):417–424. https://doi.org/10.1016/j.jhazmat.2010.08.051 Schroeder D (1984) Soils – facts and concepts. Internationales Kali-Institut, Bern Şengül AB, Ersan G, Tüfekçi N (2018) Removal of intra- and extracellular microcystin by submerged ultrafiltration (UF) membrane combined with coagulation/flocculation and powdered activated carbon (PAC) adsorption. J Hazard Mater 343:29–35. https://doi.org/10.1016/j. jhazmat.2017.09.018 Su Y, Deng Y, Du Y (2013) Alternative pathways for photocatalytic degradation of microcystin­LR revealed by TiO2 nanotubes. J Mol Catal A Chem 373:18–24. https://doi.org/10.1016/j. molcata.2013.02.031 Suzuki Y, Saitoh H, Kamata Y, Aihara Y, Tateyama Y (1989) Precipitation Incidence of the Lanthanoid(III) Hydroxides: II. Precipitation from chloride and perchlorate solutions. J Less Common Met 149:179–184 Tachikawa T, Tojo S, Kawai K, Endo M, Fujitsuka M, Ohno T, Nishijima K, Miyamoto Z, Majima T (2004) Photocatalytic oxidation reactivity of holes in the sulfur- and carbon-doped TiO2 powders studied by time-resolved diffuse reflectance spectroscopy. J Phys Chem B 108(50):19299–19306. https://doi.org/10.1021/jp0470593 Teng W, Wu Z, Fan J, Chen H, Feng D, Lv Y, Wang J, Asirid AM, Zhao D (2013) Ordered mesoporous carbons and their corresponding column for highly efficient removal of microcystin­LR. Energy Environ Sci 6:2765–2776 Tian S, Jiang P, Ning P, Su Y (2009) Enhanced adsorption removal of phosphate from water by mixed lanthanum/aluminum pillared montmorillonite. Chem Eng J 151(1–3):141–148. https:// doi.org/10.1016/j.cej.2009.02.006 Triantis TM, Fotiou T, Kaloudis T, Kontos AG, Falaras P, Dionysiou DD, Pelaez M, Hiskia A (2012) Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2. J Hazard Mater 211–212:196–202 Tu C, Wang S, Qiu W, Xie R, Hu B. (2016) Phosphorus removal from aqueous solution by adsorption onto la-modified clinoptilolite. Matec Web of Conferences, 67. https://doi.org/10.1051/ matecconf/2016 Urano K, Tachikawa H, Kitajima M (1992) Process development for removal and recovery of phosphorus from wastewater by a new adsorbent. 4. Recovery of phosphate and aluminum from desorbing solution. Ind Eng Chem Res 31(6):1513–1515. https://doi.org/10.1021/ie00006a013

202

R. Cheng et al.

Vimont A, Goupil J, Lavalley J, Daturi M, Surblé S, Serre C, Millange F, Férey G, Audebrand N (2006) Investigation of acid sites in a Zeotypic Giant pores chromium(III) carboxylate. J Am Chem Soc 128(10):3218–3227. https://doi.org/10.1021/ja056906s Wang F, Gao Y, Sun Q, Chen Z, Megharaj M (2014) Degradation of microcystin-LR using functional clay supported bimetallic Fe/Pd nanoparticles based on adsorption and reduction. Sep Purif Technol 170:337–343. https://doi.org/10.1016/j.cej.2014.06.003 Wang X, Wang X, Ma R, Wang J, Tong X, Chen Y (2017) Efficient visible light-driven in situ photocatalytic destruction of harmful alga by worm-like N,P co- doped TiO2/expanded graphite carbon layer (NPT- EGC) floating composites. Cat Sci Technol 7:2335–2346 Wei G, Quan X, Fan X, Chen S, Zhang Y (2017) Carbon-nanotube-based Sandwich-like hollow Fiber membranes for expanded microcystin-LR removal applications. Chem Eng J 319:212–218. https://doi.org/10.1016/j.cej.2017.02.125 Wiegand C, Pflugmacher S (2005) Ecotoxicological effects of selected cyanobacterial secondary metabolites a short review. Toxicol Appl Pharmacol 203(3):201–218. https://doi.org/10.1016/j. taap.2004.11.002 Wolf D, Georgic W, Klaiber HA (2017) Reeling in the damages: harmful algal blooms’ impact on Lake Erie’s recreational fishing industry. J Environ Manag 199:148–157. https://doi. org/10.1016/j.jenvman.2017.05.031 Wu R, Lam KH, Lee J, Lau TC (2007) Removal of phosphate from water by a highly selective La(III)chelex resin. Chemosphere 69:289–294. https://doi.org/10.1016/j.chemosphere.2007.04.022 Wu L, Lan J, Wang S, Zhu J (2017a) Synthesis of N-doped carbon Xerogel (N-CX) and its applications for adsorption removal of microcystin-LR. Z Phys Chem 231(9). https://doi.org/10.1515/ zpch-­2016-­0912 Wu S, Lv J, Wang F, Duan N, Li Q, Wang Z (2017b) Photocatalytic degradation of microcystin-LR with a nanostructured photocatalyst based on upconversion nanoparticles@TiO2 composite under simulated solar lights. Sci Rep-UK 7(1). https://doi.org/10.1038/s41598-­017-­14746-­6 Xia W, Zhang X, Xu L, Wang Y, Linc J, Zou R (2013) Facile and economical synthesis of metal– organic framework MIL-100(Al) gels for high efficiency removal of microcystin-LR. RSC Adv 3:11007–11013. https://doi.org/10.1039/C3RA40741A Xie J, Lin Y, Li C, Wu D, Kong H (2015) Removal and recovery of phosphate from water by activated aluminum oxide and lanthanum oxide. Powder Technol 269:351–357. https://doi. org/10.1016/j.powtec.2014.09.024 Yan H, Gong A, He H, Zhou J, Wei Y (2006) Adsorption of microcystins by carbon nanotubes. Chemosphere 62:142–148. https://doi.org/10.1016/j.chemosphere.2005.03.075 Yang J, Zhou L, Zhao L, Zhang H, Yin J (2011) A designed nanoporous material for phosphate removal with high efficiency. J Mater Chem 21:2489–2494. https://doi.org/10.1039/ c0jm02718a Yang J, Yuan P, Chen HY, Zou J, Yuan Z (2012) Rationally designed functional macroporous materials as new adsorbents for efficient phosphorus removal. J Mater Chem A 22:9983–9990. https://doi.org/10.1039/c2jm16681j Yang J, Zeng Q, Peng L, Lei M, Song H, Tie B, Gu J (2013) La-EDTA coated Fe3O4 nanomaterial: preparation and application in removal of phosphate from water. J Environ Sci China 25(2):413–418. https://doi.org/10.1016/S1001-­0742(12)60014-­X Yang K, Yan L, Yang Y, Yu S, Shan R, Yu H, Zhu B, Du B (2014) Adsorptive removal of phosphate by Mg–Al and Zn–Al layered double hydroxides: kinetics, isotherms and mechanisms. Sep Purif Technol 124:36–42. https://doi.org/10.1016/j.seppur.2013.12.042 Yu Y, Chen JP (2015) Key factors for optimum performance in phosphate removal from contaminated water by a Fe-Mg-La tri-metal composite sorbent. J Colloid Interface Sci 445:303–311. https://doi.org/10.1016/j.jcis.2014.12.056 Yu X, Zhou J, Wang Z, Cai W (2010) Preparation of visible light-responsive AgBiO3 bactericide and its control effect on the Microcystis aeruginosa. J Photochem Photobiol B Biol 101(3):265–270. https://doi.org/10.1016/j.jphotobiol.2010.07.011

5  Nanomaterials for Effective Control of Algal Blooms in Water

203

Zamparas M, Zacharias I (2014) Restoration of eutrophic freshwater by managing internal nutrient loads. A review. Sci Total Environ 496:551–562. https://doi.org/10.1016/j. scitotenv.2014.07.076 Zeng L, Li X, Liu J (2004) Adsorptive removal of phosphate from aqueous solutions using iron oxide tailings. Water Res 38(5):1318–1326. https://doi.org/10.1016/j.watres.2003.12.009 Zhang X, Jiang L (2011) Fabrication of novel rattle-type magnetic mesoporous carbon microspheres for removal of microcystins. J Mater Chem A 21:10653–10657. https://doi.org/10.1039/ c1jm12263k Zhang G, Liu H, Liu R, Qu J (2009) Removal of phosphate from water by a Fe-Mn binary oxide adsorbent. J Colloid Interface Sci 335:168–174. https://doi.org/10.1016/j.jcis.2009.03.019 Zhang J, Lei J, Xu C, Ding L, Ju H (2010) Carbon nanohorn sensitized electrochemical immunosensor for rapid detection of microcystin-LR.  Anal Chem 82:1117–1122. https://doi. org/10.1021/ac902914r Zhang G, Zhang YC, Nadagouda M, Han C, O’Shea K, El-Sheikh SM, Ismail AA, Dionysiou DD (2014) Visible light-sensitized S, N and C co-doped polymorphic TiO2 for photocatalytic destruction of microcystin-LR. Appl Catal B Environ 144:614–621. https://doi.org/10.1016/j. apcatb.2013.07.058 Zhang Y, Pan B, Shan C, Gao X (2016) Enhanced phosphate removal by Nanosized hydrated La(III) oxide confined in cross-linked polystyrene networks. Environ Sci Technol 50(3):1447–1454. https://doi.org/10.1021/acs.est.5b04630 Zhang X, Sun F, He J, Xu H, Cui F (2017) Robust phosphate capture over inorganic adsorbents derived from lanthanum metal organic frameworks. Chem Eng J 326:1086–1094. https://doi. org/10.1016/j.cej.2017.06.052 Zhou Q, Gibson CE, Zhu Y (2001) Evaluation of phosphorus bioavailability in sediments of three contrasting lakes in China and the UK.  Chemosphere 42:221–225. https://doi.org/10.1016/ S0045-­6535(00)00129-­6 Zong E, Liu X, Wang J, Yang S, Jiang J, Fu S (2017) Facile preparation and characterization of lanthanum-loaded carboxylated multi-walled carbon nanotubes and their application for the adsorption of phosphate ions. J Mater Sci 52(12):7294–7310. https://doi.org/10.1007/ s10853-­017-­0966-­0

Chapter 6

Nanotechnological Developments in Nanofiber-Based Membranes Used for Water Treatment Applications Erkan Yilmaz and Mustafa Soylak

Abstract  With the constant acceleration of global industrialization and urbanization, the increase of urban economic level, the ever-increasing problem of water pollution is becoming more and more serious and causes a major threat to people’s production, life and physical and mental well-being. Commonly used water treatment methods include membrane filtration, catalytic decomposition, adsorption and organic/inorganic chemistry. When compared with the other methods, the membrane filtration method has gained great market prospect because of its unique use advantages such as low operation cost and energy consumption, simple and quick operation, high purification efficiency, cleanness and environmental protection. The used commercially available filtration membranes are generally composed of polymer structure such as polyvinylidene fluoride, mixed cellulose esters, polyether sulfone and so on. However, the use of such conventional filtration membranes cause important problems of low mechanical, thermal stability, low porosity, quick fouling and poor pore connectivity, which can lead to limited filtration efficiency and high operation cost. Nanotechnology and nanomaterials are used in the best possible applications to develop new membranes have high performance for water treatment process lead to the solution of the global water crisis. Nano-scale materials can be designed to display novel and importantly enhanced physical and chemical features. Nanofibers are an excellent member of the nanomaterials that offers unique properties to users depending on nanoscale diameters and wide aspect ratios. The advancement of E. Yilmaz Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, Kayseri, Turkey ERNAM Erciyes University, Nanotechnology Application and Research Center, Erciyes University, Kayseri, Turkey e-mail: [email protected] M. Soylak (*) Department of Chemistry, Faculty of Sciences, Erciyes University, Kayseri, Turkey e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_6

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nanofiber technology provides suitable tools for producing nanofiber-based membranes have excellent chemical, physical and mechanical behavior, large surface area to volume ratio and they have special characteristics attractive for advanced water treatment applications. When the literature studies on water treatment are examined, it is seen that there are approximately 1300 articles, 170 patent and over one hundred commercial membranes products in which the nanofibers are used for the water treatment methods. While there was no any study in the literature on the use of nanofibres for water treatment methods in 2000, the number of the published reports increased to about ~20 in 2007 and increased to about ~174 in 2017. With the rapid increase in the interest that exists about the nanofiber-based membranes, here we provide an overview of problems in nanofiber membranes, nanotechnological solutions and innovations in nanofiber membranes used in membrane process for water and waste water treatment. Keywords  Water treatment · Membrane technology · Nanofiber membranes · Electrospinning · Microfiltration · Ultrafiltration · Nanofiltration · Membrane distillation · Air gap membrane distillation · Osmosis-based membranes

Abbreviations NM NPs NFMs MF UF NF MD AGMD EO RO FO PRO HFMs MMMs TOC CP ICP 2D 3D ENMs CNT

Nanomaterial Nanoparticles Nanofiber membranes Microfiltration Ultrafiltration Nanofiltration Membrane distillation Air gap membrane distillation Engineered osmosis Reverse osmosis Forward osmosis Pressure-retarded osmosis Hollow fiber membranes Mixed matrix membranes Total organic carbon Concentration polarisation Internal concentration polarization Two-dimensional Three-dimensional Electrospun nanofiber membranes Carbon nanotube

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MWCNT Multiwalled carbon nanotube GO Graphene oxide PAN Polyacrylontrile PEO Poly(ethylene oxide) PET Poly(ethylene terephthalate) PES Polyethersulfone PS Polystyrene PVC Poly(vinyl chloride) PVA Poly(vinyl alcohol) PCL Poly(e-caprolactone) PPTA Poly(p-phenylene terephthalamide) PVDF Poly(vinylidine fluoride) PBI Polybenzimidazole PUS Polyurethanes PVP Poly(vinyl phenol) PVAc Polyvinyl acetate PSF Polysulfone PANCMI Poly acrylonitrile-co-maleimide PAA Poly(acrylic acid) PIA Poly(itaconic acid) ANF Aramid nanofiber PI Polyimide PEI Polyetherimide PA Polyamide APTES 3-aminopropyltriethoxysilane TFNC Thin film nanocomposite LEP Liquid entry pressure

6.1  Introduction The increase in the world population, the widespread and technological advances in urbanization are accompanied by the depletion of natural resources, the deterioration of structures, and sometimes even abandonment (Liu et  al. 2018; Ren et  al. 2018; Pirhashemi and Habibi-Yangjeh 2017). For many years, mankind has seen air, water, and land as infinite and free sources, thought to be able to get rid of them by simply pushing their waste out of their living quarters. This pollution destroys the balance of nature and threatens its livelihood (Luo et  al. 2018; Zaki and Shoeib 2018). The pollution that we can order like water, air, soil can be formed as a result of industrial processes, power plants, domestic wastes, agricultural-animal husbandry and agricultural applications (Lacalle et  al. 2018; Medina et  al. 2018; Sigmund et al. 2018). With the increase of population and the development of technology, environmental pollution has become a very important problem (Wang et al.

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2018a, b, c; Schuenemann et al. 2016). In order to meet the needs of modernization, it should be essential to keep up with this progress, as well as to minimize environmental problems using advanced scientific and social techniques (Joshi and Beck 2018). Environmental awareness has become widespread in the twenty-first century, along with the environmental concerns associated with the globally aging earth, the global climate change justifying these concerns, and the obvious changes in the quantity and quality of natural resources being felt by the world population and the visual and written publications that are common to all these issues (Kristensen et al. 2017; Joshi and Beck 2018). With the globalization, the need for governments to set common environmental policies, the problem of the earth, the understanding that solutions and improvements can be made possible through common wisdom and practices without the distinction of state, nation and geography has become an irrefutable fact of our time (Zhang et al. 2004; Rao et al. 2017; Grether and De Melo 2003; O’Bannon et al. 2014). Water pollution is an important dimension of environmental pollution (Gleick 2000; Bouwer 2002; Gleick 2003; Rosegrant 1997). The living beings are undoubtedly the indispensable need and source of life. Despite being in a continuous water cycle, water on earth is consumed without completing the cycle because of population growth, environmental pollution, cost, unconscious water consumption, changes in climatic conditions (Vörösmarty et al. 2010; Wang et al. 2008; Saeijs and Van Berkel 1995). Worldwide, 884 million people don’t access to convenient drinkable water and 1.8 million children die every year from diarrhea mostly because of water contamination (Tadesse et al. 2013). There is an immediate requirement to ensure purchasable water treatment in developing countries, where water and waste water substructure are generally not available. Even water supply networks in developed countries face various challenges. Acquisition of agricultural, industrial, drinking and potable water has become increasingly difficult for countries. For this reason, the strategic importance known in world history of water will continue to increase in future periods. Water pollution is mainly due to organic substances, heavy metals and microorganisms which cause excessive biological growth using dissolved oxygen and have biodegradation and toxic effects on aquatic life if their concentration reaches a certain value (Tadesse et al. 2013; Israr et al. 2015; Brix 1994). Waste water occurs in groundwater, rivers, lakes and seas. Water contaminated, partially or totally altered by waste water, domestic, industrial, agricultural and other uses, as well as water derived from mines and ore preparation plants, is converted into surface or subsurface flow in rainy conditions in streets, parking lots and similar areas from structured plastered and uncovered urban areas can be defined as waters (Sakkayawong et al. 2005). Factors causing pollution in the waste water and causing environmental pollution accordingly; inorganic substances (antimony, arsenic, boron, copper, barium, zinc, lead, nickel chrome, tin, cobalt, silver) (Daskalaki et al. 2010; Liu et al. 2005; Manohar et al. 2002), organic compounds (proteins, carbohydrates, oils and grease, surfactants, phenols, pesticides, chlorinated compounds, cyanide, polychlorobiphenyl (PCB), polybromophenyl (PBB), aromatic and aliphatic hydrocarbons, asbestos) (Lefebvre and Moletta 2006; Martinez-Huitle and

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Ferro 2006; Ali et al. 2012), microorganisms (bacteria, viruses and other living and died cells remains) (Baron 1997; Stottmeister et al. 2003; Rojas-Valencia 2011). Approaches such as finding new water sources, using underground waters, bringing water from another region to the water-scarce and water-demanding regions when the problems are encountered meet the existing water needs for a certain period of time, but are not sustainable solutions because they will lead to the depletion of existing water resources. The permanent solution is that the water is not polluted and the water contaminated with different pollutants is cleaned and re-used by suitable methods. In this context, scientists are developing methods to combat with pollution, especially water pollution, which is one of the most important problems affecting human health. What is important here is to find effective and continuous methods to reduce the cost of water treatment process (Hansen and Bhatia 2004;, Abbey 2013). During the production of chemical substances, hazardous waste waters are produced as a by-product and these waste waters because serious problems when they are given to the environment without being treated (Henze et al. 2001). Moreover, water contamination is not only limited to water resources but also causes food contamination by entering the food chain (Khan et al. 2008). Waste water containing these pollutants must be checked for compliance with water standards and the pollutant content should be reduced to the desired level. For this reason, waste waters containing hazardous pollutants need to be provided to the main treatment system after treatment in a pre-treatment system (Gray 2010; Hammer 1986). The type of contaminant should then be converted to less harmful by appropriate treatment. For this purpose, the use of physical, chemical and biological treatments to convert waste waters into waters as a result of various uses and to make it possible to recover some or all of the chemical, physical and bacteriological properties lost and/or to change the natural, physical, chemical, bacteriological and ecological characteristics of the receiving environment one or more are applied together. When considering the concerns about the feasibility of current practices on the importance of drinking water for people and other living cells and for meeting the increasing demands of all water users (Muller et al. 1995; Ternes et al. 2002). There is a clear need to develop innovative new technologies and materials to address the challenges associated with providing safe drinking water (Westerhoff et al. 2005). Although new approaches are constantly being scrutinized, they need to be durable and more effective at lower cost than the options available for pollutants to be disposed of in water or in water treatment systems. Nanotechnology has been described as an innovative technology that can play an important role in solving or improving many problems related to water treatment and quality (Qu et  al. 2013; Mahadik 2017). Although there is no exact definition of nanoscience and nanotechnology, according to the general view nanotechnology; it can be defined as the understanding, control, atomic level modification and functionalization of materials in sizes of 10–100 nm or smaller (Qu et al. 2013). The most common comment about nanoscience is; monitoring, design and production at atomic and molecular dimensions, and processing new properties at these dimensions. Nanotechnology plays with atoms. It is based on the principle of creating the desired structure by maneuvering

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atoms and molecules one by one. The most meaningful statement about the importance of nanotechnology is expressed by the Nobel Prize-winning Horst Stormer of the University of Colombia’s academics in physics. According to Stormer; “Nanotechnology gives the perfect box of toys to play with atoms and molecules in human beings, so everything can be done with this technology” Nanotechnology; is a comprehensive term that broadly defines science and technology that control nanoscale materials (Arain et  al. 2018; Baghban et  al. 2017; Mnyusiwalla et al. 2003; Ritala and Leskelä 1999). The ability to interfere with any material in the atomic dimension is undoubtedly the subject of mutual interactions of many sciences (Daniel and Astruc 2004). Together with developments in science and technology, scientific and industrial science (chemistry, biology, physics etc.) and engineering sciences (electronics, computer, materials, mechanics etc.) will become interdisciplinary studies and become a science discipline with a lot of alternatives to nanotechnology and nanoscience (Daniel and Astruc 2004; Maynard et al. 2006; Paul and Robeson 2008; Mohanpuria 2008). In the last few decades, nanoscience has grown before infancy and combining unique thermal, mechanical, electronic and biological properties, has resulted in significantly improved performance and new applications in physics, chemistry, biology, engineering, medical science etc. (Sahoo et al. 2007; Sarikaya et al. 2003; Park 2007). The remarkable properties of nanomaterials such as high surface area, light sensitivity, catalytic and antimicrobial activity, optical, electrochemical and magnetic properties, adjustable pore size and surface chemistry, supple important advantageous for many applications and allow the development of new high-tech materials for more effective water and waste water treatment processes such as membranes, adsorption materials, nanocatalysts, functional surfaces, coatings and reagents etc. (Hutchison 2008; Valcarcel et al. 2005). The potential effect fields of nanotechnology in water applications are consisting of three categories such as sensing and detection, treatment and remediation and pollution prevention (Brame et al. 2011; Qu et al. 2012; Theron et al. 2008; Hillie and Hlophe 2007). In the detection and sensing category, it is particularly important to develop new and improved sensors to detect very low levels of chemical and biological contaminants in the different type of water (Cloete 2010; Adams et al. 2002). In the treatment and remediation category, nanotechnology provides important contributions for long-term water quality, availability and vitality of water resources, such as advanced filtration materials that make possible more water recycling, and desalination (Zhu et  al. 2009; Wang et al. 2012). Furthermore, nanotechnology has the potential to make easy the improvement of continuous monitoring devices that can provide real-time measurements and improved specificity at a lower cost. On the basis of the uses of nanotechnology and nanomaterials in areas relevant to water purification methods have mainly four types of relationships: (1) Membrane filtration, (2) adsorption, (3) catalysts and (4) disinfection (Zularisam et al. 2006; Ali and Gupta 2006; Chong et al. 2010; Gyürék and Finch 1998). Membrane is a semi-permeable material made of inorganic materials or organic polymers that restricts the movement of certain species in between two phases and is used for continuously selective separation of gas, solid/liquid and liquid/liquid (Feng and Huang 1997; Hanioka et al. 2008; Nunes and Peinemann 2001). Due to

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the development of numerous membrane systems with different separation mechanisms, and the fact that they provide effective solutions to the problems encountered in separating a large number of substances from aqueous medium and provide a very important advantages in water treatment (Nicolaisen 2003; Jacangelo et  al. 1997; Magara et al. 1998). These advantages are as follows; Simple modification and design of system, lower energy consumption than classical systems, low operating and maintenance cost, continuous operation capability and automation simplicity, no effect on the chemical structures or forms of pollutants, don’t require any chemical addition and no being affected by changes in water or waste water properties (Baker 2000; Ahmad et al. 2003; Pérez-González et al. 2012). Besides these important advantages, these systems have the following disadvantages that scientists constantly work on, as follows; Membrane contamination causing low membrane life, low selectivity and flow and more or less linear scaling factor (Ahmad et  al. 2003; Pérez-González et  al. 2012). The right choice of membrane type is crucial for obtaining an optimized filtration process in terms of capacity, efficiency and efficiency. In performance and application based classification, the water filtration membranes are examined in three groups as sieving, functionalized (affinity) and sieving-functionalized membranes. In the sieving mechanism, the sizes of the pollutions are needed to be considered and membranes with pore size smaller than the size of the pollutions are needed. Functionalized membranes, on the other hand, are used the separation of molecules taking into account the biological/chemical properties or biological functions rather than the molecular weight/size (Ho and Zydney 2000; Lim and Bai 2003). When a classification is made according to the working system, Microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), membrane distillation (MD) and engineered osmosis (e.g., reverse osmosis (RO), forward osmosis (FO) and pressure-retarded osmosis (PRO)), process can be classified under the sieving membrane filtration systems. While ion exchange membranes, photocatalytic membranes, antimicrobial membranes, adsorption membranes and their combination with the sieving membranes can be classified as functionalized membrane filtration systems. The most important parameter that determines the performance of the membrane systems is the type of membrane material and activity which is shown for removal of different types of pollutants such as turbidity, most of dissolved salts, more than 300 organic species and microorganisms and hardness, as well as a fraction of the dissolved salts. Modifying membrane systems with functional nanomaterials provides an excellent opportunity to improve membrane permeability, mechanical and thermal stability, fouling resistance and to procreate new features for degradation of pollutants and self-cleaning (Tiwari et al. 2008; Savage and Diallo 2005). In the last decade, the emergency of new generation membranes consist of well-defined nanomaterials has quickly replaced the traditional materials used in membrane applications cause of birth new water treatment procedures that exceed the state-of-the-art efficiency with novel additional properties such as high chemical and thermal stability, high surface area, high mechanical strength, high flow rate, antibiotic resistance, fouling resistance, catalytic reactivity and flexibility (Theron et al. 2008; Carpenter et al. 2015). Up to now, the nanomaterial-based membrane mainly include nanofibers, polymers, metallic and metal oxide nanoparticles (NPs), carbon based

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materials, two-dimensional (2D) layer materials, three-dimensional (3D) layer materials and their composites (Xu et al. 2012; Zhong et al. 2006; Upadhyay et al. 2014). Moreover, a variety of water-treatment equipment including some that incorporate nanotechnology are already on the market and many others more are still on the way (Theron et al. 2008).

6.2  Membrane Filtration Process 6.2.1  Microfiltration and Ultrafiltration Microfiltration (MF) processes are generally used for pre-filtration of the suspended particles with diameters between 0.1 and 10μm such as solid particles, bacteria, viruses, organic compounds, heavy metal ions in waste water before ultrafiltration, reverse osmosis, nanofiltration and other membrane process (Ho and Zydney 2000; Lim and Bai 2003). In this way, the reverse osmosis and nanofiltration membranes can be used for a long time without being cleaned and unchanged. In addition to pre-filtration applications, with the development of modified microfiltration membranes by nanotechnological applications in recent years, microfiltration process have become available in different applications such as separation of oil-water mixture and removal of multiple pollutants including purification and disinfection at the same time (Ho and Zydney 2000; Lim and Bai 2003; Dijkshoorn et  al. 2017). Ultrafiltration (UF) is another important filtration process used to remove various contaminants such as viruses, emulsions, proteins and colloids ranging from about 1 to 100 nm (Papageorgiou et al. 2012; Zularisam et al. 2006). By modifying the membranes used in the ultrafiltration processes, it is possible to use ultrafiltration membranes for a number of applications mentioned in microfiltration process. Although conventional microfiltration and ultrafiltration membranes can be used in a wide range of ways to remove contaminants and separate components in water, the major disadvantages that limit the use of conventional microfiltration and ultrafiltration membranes are the low mechanical stability due to high working pressure, tendency to low flux and high fouling problems arising from the corresponding pore size dispersion, geometrical structure of pores, and formation of undesirable voids throughout the entire membrane thickness. One of the best ways to reduce or eliminate the above-mentioned disadvantages of microfiltration and ultrafiltration membrane systems is to use nanofibers, nanocomposite or nanofiber/nanocomposite membranes have desired features in these membrane technologies.

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6.2.2  Nanofiltration Nanofiltration (NF) membranes can either be applied for treatment all types of water including ground, surface, and waste water. The nanofiltration (NF) process is used to remove inorganic ions, organic materials and microorganism especially in aqueous solutions (Radjenović et  al. 2008; Mondal and Wickramasinghe 2008; Costa and De Pinho 2006). The history of nanofiltration dates back to the 1970s. But about the second half of the 1980s, the first applications of nanofiltration systems were reported (Sayed et  al. 2007). The nanofiltration process is between reverse osmosis and ultrafiltration in terms of membrane pore diameter. Microfiltration and ultrafiltration process are operated at higher pressures because they are dense and thin, but the membrane layer which is less permeable indicates the presence of the membrane layer (Radjenović et  al. 2008; Mondal and Wickramasinghe 2008). Nanofiltration membranes are operated at lower pressures than reverse osmosis membranes and deliver water at a lower quality than reverse osmosis membranes. Hence, such low-pressure reverse osmosis membranes became known as nanofiltration membranes (Thanuttamavong et al. 2002). Nanofiltration combines the charge effects between the surface of the membrane and solution to remove uncharged compounds and multivalent ions at nanoscale (Chen et al. 2018; Wang et  al. 2018a, b, c). The removal of uncharged components depends on the size, charge, polarity and solubility of the molecules, which may lead to differences in diffusion rates in a non-porous structure. The charge effect is also directional force for removal of charged components. The mechanism of removal of multivalent ions contaminant in nanofiltration membranes was found to be better selective for higher valence ions compared to reverse osmosis membranes and to have higher flux (Lhassani et  al. 2001). An important and different feature of nanofiltration membranes is that they must be ion selective. Possibility through a nanofiltration membrane of a salt is strongly dependent on the value of the positively and negatively charged ions forming the salt. A valent ion passes through the membranous membrane. But the two and trivalent ions are kept in the important position (Nativ et  al. 2018). There are various applications in nanofiltration such as removal of color, pesticides and total organic carbon (TOC) from surface water, removal of radium or hardness from well water, removal of total dissolved solids (TDS), and organic separation from inorganic matter in special food and waste water applications (Favre-Réguillon et al. 2008; Ochando-Pulido and Martinez-Ferez 2018; Lv et al. 2018; Hedayatipour et al. 2017). The properties of nanofiltration membranes make up the typical applications of the following: 1. Holding multivalent anions as a valence ion pass through on nanofiltration membranes for: • Process and softening of drinking water systems. • Pre-purifier for ion exchanger or reverse osmosis systems.

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2. Retention of organic compounds when passing a valent salt for: • • • •

Treatment of drinkable water Treatment of textile and paper industry based waste water Retention of lactose and proteins from the pasteurized water Removal of salt in waste water

3. Separation of low and high molecular substances in aqueous solutions for: • Drinking alcohol • Prior to the biological treatment step, separation of hardly broken materials in the waste water.

6.2.3  Osmosis Based Membranes Up to now, a lot of modern procedures based on membrane technology have been used for water reclamation and desalination (Vital et  al. 2018; Xu et  al. 2018; Sánchez 2017). Reverse osmosis (RO) is one of the most common applications used for 40 years to an 80% share in the total number of desalination foundation set worldwide and a 44% share in world desalting production capacity (Vital et  al. 2018; Xu et al. 2018; Sánchez 2017; Masindi et al. 2017). But there are some problems that restrict the use of the reverse osmosis membrane system such as high operating cost, limited amount of recoverable water and adverse effects on the environment due to toxic residues after reverse osmosis treatment. In addition to these problems, many saline solutions (>3.5% salt concentration) are not suitable for desalination using the reverse osmosis methods due to membrane scaling and contamination and the high costs of pumping system supply high pressure. Hence there is a need for innovations in reverse osmosis membrane process or an alternative cheap process to minimize these drawbacks (Herzberg and Elimelech 2007; Zhu et al. 2010). While a group of researchers believe that these problems can be solved and an increase on the usage ratio of membrane desalination process can be achieved with the production of new and innovative materials, the other researcher provide that the nanofiltration (NF), forward osmosis (FO), pressure-retarded osmosis (PRO) and membrane distillation (MD) system will emerge as an important technology that can overcome the some problems of reverse osmosis (RO) systems and the water shortage problems (Cath et al. 2006; Alkhudhiri et al. 2012). Despite these methods can overcome the some problems of reverse osmosis, there are still have some important limitations. The forward osmosis process is a state-of-the-art membrane process that the automatically passage of water through the membrane via natural osmotic pressure as the driving force, which offers benefits over traditional pressure-driven membrane process (Alkhudhiri et al. 2012). As a new separation/desalination membrane application, it attracts attention of researchers and users in recent years because of its important contributions such as superior rejecting rate and ideal effluent quality

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for membrane (Zhao et al. 2012). In recent years, forward osmosis and pressure-­ retarded osmosis membrane applications have been used in a number of water treatment processes such as seawater desalination and the treatment of various waste streams (industrial waste water, landfill leachate, etc.). However, industrial applications of forward osmosis (FO) and pressure-retarded osmosis (PRO) have been restricted due to its disadvantages like membrane fouling, lower permeate water flux compared to pressure driven membrane applications, concentration polarisation (CP), reverse salt diffusion and the energy consumption of draw solution recovery (Chung et al. 2012; Gray et al. 2006). So, in order to solve problems mentioned above, the necessity of new membrane system for osmosis based process is still continuing. The use of nanotechnology and nanomaterials in osmosis based process is an effective and innovative way on solutions of these drawbacks.

6.2.4  Membrane Distillation Membrane distillation (MD) is a temperature-based procedure and is worked by creating a temperature difference between the feed stream and the permeate stream along the membrane (Lawson and Lloyd 1997). Thus, in membrane distillation technology, the driving force for diffuse transport is the difference in the vapor pressure, which exponentially changes with the temperatures of the feed and permeate streams (Alklaibi and Lior 2005). Since there is no need for high pressures in membrane distillation processes, fouling and scaling problems, which faced the other processes, have been overcome in membrane distillation process. So, lesser pretreatment step is needful. Hence, compact membrane distillation systems can be fabricated by using stainless and inexpensive plastic materials due to low hydraulic pressure (Alkhudhiri et al. 2012; Al-Obaidani et al. 2008). Up to now, it provides a very promising possibility for mobile and fixed alone desalination applications. But, it still needs to overcome some problems so that it can be used as a completely commercial product. These problems are as follows; (1) Absence of suitable membranes, In the membrane distillation processes, a hydrophobic and porous membrane is required for separation of saline feed and desalted condensate. Most of the membrane distillation process, commercially available flat sheet or hollow fiber microfiltration membranes are generally used because of their sufficient pore sizes, hydrophobic characteristic and well porosity (Khayet 2011). But, these microfiltration membranes are not preferably fabricated for membrane distillation due to their wetting problem and low flux rate in long-dated performance, (2) Suitable and effective module production, and (3) excessive consumption of energy in the absence of solar, waste heat or other alternative energy source. Hence, there is a need to design and produce new membranes and modules and to solve energy problems for membrane distillation process. Most of these problems have been solved with the development of nanotechnology and nanomaterials (Cabassud and Wirth 2003; Phattaranawik et  al. 2003). Despite important advancements in our understanding of the membrane process, questions and challenges remain regarding

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current state of the nanotechnology. Hence, here we provide an overview of nanotechnological innovations in nanofiber membranes used in membrane filtration process for water treatment. The water purification applications mentioned next sections are all in the stage of laboratory research with noted exceptions that are being field tested.

6.3  Nanofiber-Based Membranes and Applications Nanofibers are an excellent member of the nanomaterial that offers important properties to users depending on nanoscale diameters and wide aspect ratios. The nanofiber term is classified to a fiber having a diameter of 100 nm or less (Zhou and Gong 2008; Tennent et al. 2000; Bond et al. 2009). The advancement of nanofiber technology provides suitable tools for producing nanofiber products have as excellent mechanical behavior and large surface area to volume ratio and they are useful for many health, energy and environmental applications (Zhou and Gong 2008; Tennent et  al. 2000; Bond et  al. 2009). In order to produce nanofibers, different types of techniques, such as electrospinning, multi-component spinning, flash spinning, melt-blowing, self-assembly, template synthesis and nanolithography are used (Ignatious et al. 2010; Okamoto et al. 1977; Zhou and Gong 2008; Ellison et al. 2007; Hartgerink et al. 2001; Liang et al. 2012; Pisignano et al. 2005). Among these techniques, the electrospinning technique as an easy, cheap and effective method has important role for fabricating ultra-fine nanofibers from various materials (e.g., polymers, carbon nanotubes, fullerenes, graphene, graphene oxide, nano-sized metals and metal oxides, nano-sized zeolites, ceramics, and alumina, or even chitosan) for membrane systems (Sen et al. 2004; Mohamed et al. 2017; Thakur et al. 2018). The resulting nanofibers have high specific surface area, which lead to high functionalization ability, high porosity, tailorable membrane thickness and form nanofiber mats with complex pore structures and environmentally benign nature and so on (Mohamed et al. 2017; Thakur et al. 2018). The practicality of the electrospinning production method for membrane technology has grown largely due to recent developments in scalability in mass production, cause to higher production speeds and lower cost materials (Chen et al. 2017). Electrospinning is a polymer solution spinning procedure, which lead to formation of nanofibers from a charged polymer solution or melt, controlled by an electric field. In this procedure, the formation of nanofibers has been controlled by the use of an electrical field induced by a high-­ voltage power supply between the polymer solution or melt in a spinneret and a collector (a counter or grounded metal electrode) conveniently located at an appropriate distance (Moradi et al. 2018; Shariful et al. 2018). The following three different production procedures, which, enables to obtain membranes with different properties, are mainly used in synthesis of electrospinning based nanocomposite/electrospun nanofiber membrane materials;

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1. Electrospinning for production of multicomponent fibers such as core/shell nanofibers and sol-gel nanocomposite based on two or more precursor solutions. 2. Electrospinning for production of nanofiber/inorganic nanoparticles based on polymer solutions consist of homogenously dispersed inorganic nanoparticles and also carbon nanotubes, graphene, graphene oxide and fullerene. 3. Electrospinning for production of composite/hybrid nanofibers based on surface functionalization of the electrospun nanofibers. The chemical composition, chemical and physical properties, functional groups, spatial alignment, diameters and secondary structure of the resulting electrospun nanofibers can be easily manipulated for specific applications (Ahmadi et al. 2017). The developments of these nanofibres, which can be prepared by modification of many nanomaterials, have different physical and chemical properties, leads to the evolution of water treatment technologies based on membrane filtration systems. Their functionality and applicability is even promoted when adopting a nanocomposite strategy (Ahmadi et al. 2017; Aydogdu et al. 2018; Wang et al. 2018a, b, c). Although nanofiber membranes are commercially available for use in air filtration systems, the potency of water treatment have a quite short history and remains largely unexplored. But in fact nanofiber membrane for water treatment process can be take the place of traditional processes in industrial area because of the their important benefits such as easy control mechanism, cheap operating cost, low energy consumption, production of superior quality products and flexible design (Puguan et al. 2014; Zong et al. 2003). Hence it is essential to carry out scientific studies on nanofiber water treatment systems that promise high application area and commercial potential for the future. When compared with the other membrane systems, nanofiber membranes based polymer have poor mechanical strength attributed to their nanosized fiber diameters, non-woven and extremely porous construction, and weak bonding between the fibers. For example, Hou observed that the tensile strength of traditional fibers is approximately 10–100 times higher than polyacrylontrile (PAN) electrospun nanofiber membranes (ENMs) (Hou et  al. 2005). This situation has limited the use of polymer based electrospun nanofiber membranes in filtration because they are affected from high pressure more than 130 psig and due to the effect of this pressure, deformations occur in the inner structure of electrospun nanofiber membranes (Chitpong and Husson 2017a, b). In addition to mechanical strength problem of polymer based electrospun nanofiber membranes, the nanofibers used in the nanofiber membrane applications do not have the desired hydrophobicity and the easy contamination of the fibers, cake or gel layer formation and pore blocking are other factors that restrict the use of these membrane systems (Im et al. 2008). The idea of the use of nanofiber production systems together with the other nanotechnological applications such as waste water treatment has contributed significantly to the development of the nanofiber-based membrane systems, which provides important advantages (Aliabadi et  al. 2013; Sundarrajan and Ramakrishna 2007). To solve poor mechanical strength, easy contamination, cake or gel layer formation and pore blocking problems of the nanofiber-­ based membrane applications, to give the desired hydrophobicity to the nanofiber

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membranes and combine the use of nanofiber membranes with other nanotechnological applications, they have been fabricated or decorated with additional functionalities such as precious metals and metal oxides, carbon based materials (Carbon nanotubes, fullerenes, graphene and graphene oxide), ceramic, soluble drugs, biofilms and smart biological agents etc. via in situ reduction of NPs or via direct addition of NPs in polymer solution before electrospinning process (Formo et al. 2009; Zhang et al. 2014; Ying et al. 2017; Homaeigohar and Elbahri 2014). A combination of various moieties different in nature provides the advantages of individual components together. Nanofibers provide excellent substrate for these decorations. The novel generation of nanocomposite nanofiber membranes provide extraordinarily feature in water treatment technologies. We can explain this situation on two examples as follows; (1) The inorganic/organic nanocomposite utilizes the flexible, light, and moldability features of the organic polymers and the high strength, chemical resistance and thermal stability features of the inorganic additives. (2) To fabricate the affinity nanofiber membranes for remove heavy metals, organic pollutants and microorganism during filtration, the nanofibers can be designed with incorporating nanomaterials or specific capture agents (Feng et al. 2013; Huang et al. 2013). The important development in nanofiber production technology has paved the way to use them in membrane filtration procedures such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), forward osmosis (FO) and membrane distillation (MD) as sieving membrane filtration systems and adsorption, ion exchange, photocatalytic, and antimicrobial membrane filtration process as functionalized membrane filtration systems. Some of the new generation studies, which are based on obtaining the fiber membranes, nanofiber membranes (NFMs), nanocomposite/nanofiber membranes (NFMs) and using them in different membrane systems, are summarized below. These nanofiber membrane (NFM) and nanocomposite/nanofiber membrane (NFM) applications for water treatment process are shown in Table  6.1. In this applications, more than 100 synthetic and natural polymers such as polyacrylonitrile (PAN), poly(ethylene oxide) (PEO), poly(ethylene terephthalate) (PET), polystyrene (PS), poly(vinyl chloride) (PVC), Nylon-6, poly(vinyl alcohol) (PVA), poly(e-caprolactone) (PCL), poly(p-phenylene terephthalamide) (PPTA), poly(vinylidine fluoride) (PVDF), polybenzimidazole (PBI), polyurethanes (PUS), polycarbonates, polysulfones, poly(vinyl phenol) (PVP) and metal oxides, carbon based nanomaterials, precious metals, soluble drugs, biofilms and smart biological agents and natural bio-macromolecules etc. have hundreds of different combinations are used. The productions of different membranes used for a long time with resistance to pH and temperature changes, with high mechanical stability, the desired polarity and have antifouling properties, are among the primary goals of scientists working on nanofiber-based membrane technology (Wu et al. 2017; Islam et al. 2017; Qing et al. 2017). Recently, carbon-based new generation materials such as carbon nanotubes (CNTs), fullerene, graphene and graphene oxide (GO) have made much uses as ideal reinforcing and functionalization agents for polymers used in the membrane science and engineering due to their high chemical and thermal stability, high

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Table 6.1  Water treatment applications of nanofiber-based membranes fabricated from polymers, inorganic materials and polymer/nanoparticle hybrid materials Nanofiber-based membrane type Superhydrophobic-superoleophilic polytetrafluoroethylene nanofibrous membrane Multiwall carbon nanotubes decorated superhydrophilic poly(vinylidene fluoride) membrane Superhydrophilic wetted PVDF electrospun-TEA membrane Smart poly(vinylidene fluoride)/ poly(acrylic acid) tree-like nanofiber membrane Switchable polyacrylonitrile/carbon nanotube electrospun nanofiber membrane Silica nanoparticles/Decanoic acid-TiO2/Polyimide electrospun nanofibrous membrane Fe(OH)3@Cellulose hollow nanofiber membrane

Superoleophobic nanofiber-based meshes from waste glass Ag/TiO2 nanofiber membrane

Process Filtration

Application area Refs. Oil/water emulsion Qing et al. (2017)

Filtration

Oil/water emulsion Yang et al. (2017a, b)

Filtration

Oil/water emulsion Obaid et al. (2017) Oil/water emulsion Cheng et al. (2017)

Filtration

Filtration

Oil/water emulsion Jiang et al. (2017)

Filtration

Oil/water emulsion Ma et al. (2017a, b)

Filtrationadsorption

Zhao et al. Removal of phosphate, heavy (2017a, b) metal ions, and organic dyes. Oil/water emulsion Ma et al. (2017a, b) Liu et al. Bacteria (2012) inactivation and dye degradation Oil/water emulsion Tai et al. (2014)

Filtration Filtration

Electrospun carbon/silica nanofibrous Filtration membrane Poly(vinylidene fluoride) nanofibers Pre-filter Carbon/silica composite nanofiber membrane Polyphenylsulfone nanofibrous

Polyethersulfone electrospun nanofibrous membranes Stellate poly(vinylidene fluoride)/ polyethersulfone microsphere electrospun membrane Pd/SiOC nanofibrous membrane Polyacrylonitrile electrospun nanofiber membrane

Filtration Filtration

Pre-filtration Filtration

Microfiltration Microfiltration

Oil/water emulsion Agyemang et al. (2016) Oil/water emulsion Tai et al. (2015) Removal of turbidity total dissolved solids Water and other liquid separation Oil/water emulsion

Kiani et al. (2016) Homaeigohar et al. (2010) Cao et al. (2017)

Oil/water emulsion Wu et al. (2017) Water treatment Wang et al. (2017a, b) (continued)

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Table 6.1 (continued) Nanofiber-based membrane type Polyethersulfone electrospun nanofiber membrane Tubular electrospun nanofiber membrane Polyvinylamine grafted nanofibrous membrane Polyvinylidene fluoride tree-like nanofiber membrane Polyethylene terephthalate/ polyacrylonitrile nanofiber membrane Aramid nanofiber membrane

Nylon-6,6/chitosan/poly(vinylidene difluoride) nanofiber composite membrane Graphene/polyethersulfone hollow fiber membrane Cyclodextrin glucanotranferase/ Cellulose nanofiber membrane Carbon nanotube/polyaniline nanofiber membrane Polyamide/polyethylene terephthalate nanofiber membrane Cellulose nanofiber membrane

Process Microfiltration

Application area Water treatment

Microfiltration

Removal of turbidity and total organic carbon Removal of Cr(VI) Liu et al. (2015) Water treatemnet Li et al. (2016)

Microfiltration Microfiltration Ultrafiltration Ultrafiltration

Ultrafiltration

Ultrafiltration Ultrafiltration Ultrafiltration Nanofiltration Nanofiltration

Graphene/hot-pressed electrospun Nanofiltration polyacrylonitrile nanofiber membrane Piperazine-Polyethersulfone thin-film Nanofiltration nanofibrous composite membrane Cellulose nanofiber membrane Nanofiltration

B-cyclodextrin/ Polydopamine/ polystyrene fiber membrane Thiol-functionalizedelectrospun polyacrylonitrile nanofiber membrane Polyacrylonitrile/polypyrrole core/ shell nanofiber mats Aminated polyacrylonitrile nanofiber Polystyrene/TiO2 nanofiber membrane

Adsorption Adsorption Adsorption Adsorption Adsorption

Removal of arsenate Removal of higher toxins in hemodialysis Filtration of bovive serum albumin

Refs. Bae et al. (2016) Aslan et al. (2016)

Bahmani et al. (2017) Nie et al. (2017) Vanangamudi et al. (2017)

Oil/water emulsion Prince et al. (2016) Industrial Sulaiman et al. biocatalyst (2017) Filtration of bovive Liao et al. serum albumin (2013) Water treatment Mahdavi and Moslehi (2016) Soyekwo et al. Removal of inorganic salts and (2017) organic dyes Water treatment Wang et al. (2017a, b) Removal of salts Yung et al. (2010) Soyekwo et al. Removal of inorganic salts and (2017) organic dyes Water treatment Wang et al. (2005) Removal of Wang et al. mercury ions (2016) Removal of heavy Wang et al. metals (2014) Removal of metal Neghlani et al. ions (2011) Removal of copper Wanjale et al. (2016) (continued)

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Table 6.1 (continued) Nanofiber-based membrane type Ag NPs/MWCNTs/aminated polyacrylonitrile (APAN) nanofibrous membrane Carbon nanofiber/cellulosic membrane Silica nanoparticle/poly(vinylidine fluoride) electrospun nanofiber membrane Electrospun polyvinylidene fluoride/ polyamide thin film composite membrane Poly(ether sulfone)/nanofiber nonwoven thin film composite membrane Polyimide microporous nanofiber thin film composite membrane Polyethersulfone nanofiber based scaffold-like nanofiber thin film composite membrane Electrospun polyethylene terephthalate nanofiber based thin film composite membrane Polyetherimide nanofiber/ functionalized multiwalled carbon nanotubes/polyamide thin film composite membrane Polyacrylonitrile nanofibers/polyester nonwoven/polyamide nanofiber thin film composite membrane Polyethersulfone based thin film composite membrane Polyvinylidene fluoride nanofiber membrane Polydopamine/polyethyleneimine/ polypropylene hollow fiber membrane Fluorosilane/TiO2 nanocomposite membrane Poly(vinylidene fluoride-co-­ hexafluoropropylene)/ silica nanoparticles nanofiber membrane Graphene/electrospun polyvinylidene fluoride/co-hexafluoropropylene membrane

Process Adsorption

Forward osmosis

Application area Removal of toxic heavy metals and bacteria Desalination

Forward osmosis

Desalination

Forward osmosis

Desalination

Tian et al. (2013)

Forward osmosis

Desalination

Chowdhury et al. (2017)

Forward osmosis

Desalination

Forward osmosis

Desalination

Chi et al. (2018) Song et al. (2011)

Pressure retarded osmosis

Desalination

Hoover et al. (2013)

Forward osmosis and Pressure retarded osmosis Pressure retarded osmosis

Desalination

Tian et al. (2015)

Desalination

Bui and McCutcheon (2014) Park et al. (2016) Feng et al. (2008) Yang et al. (2017a, b)

Pressure retarded osmosis Membrane distillation Membrane distillation Membrane distillation Air gap membrane distillation Air gap membrane distillation

Desalination Desalination Desalination and water treatment

Refs. Kumar and Gopinath (2016) Dabaghian et al. (2016) Obaid et al. (2016)

Desalination

Lee et al. (2016a, b) Woo et al. Desalination and removal of organic (2017) compounds Desalination Woo et al. (2016) (continued)

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Table 6.1 (continued) Nanofiber-based membrane type Poly(acrylic acid)/cellulose nanofiber and poly(itaconic acid)/cellulose nanofiber membrane Polyacid/cellulose nanofiber membrane

Process Ion-exchange membranes (Microfiltration) Ion-exchange membranes (Ultrafiltration) Palladium/Zeolite nanofiber Catalyst membrane membrane TiO2/Ceramic hollow fiber membrane Photocatalysis Nylon-6/TiO2 nanofiber membrane

Photocatalysis

Polyacrylonitrile-ZnO/Ag composite electrospun nanofiber membrane Ag/AgCl coated polyacrylonitrile nanofiber membrane CNTs/TiO2 nanofiber membrane

Photocatalysis

Nano Fe2O3/TiO2/Activated Carbon Fiber membrane Ag NPs/poly(4-chloro-3-­ methylphenyl methacrylate) membrane Ag NPs/ three dimensional (3D) woven electrospun nanofiber membrane

Photocatalysis Photocatalysis Adsorption and Photocatalysis Antibacterial activity Filtration

Application area Removal of heavy metal ions Removal of heavy metals Water treatment Removal of humic acid Degradation of organic dye Degradation of organic dye Degradation of organic dye Water treatment

Refs. Chitpong and Husson (2017a, b) Chitpong and Husson (2017a, b) Choi et al. (2016) Zhang et al. (2016) An et al. (2014) Chen et al. (2015) Lei et al. (2011)

Zhu et al. (2013) Removal of Phenol Han et al. (2016) Water treatment Abbey (2013)

Water treatment

Zhao et al. (2017a, b)

surface area, high mechanical strength, well developed mesopores and partial antibacterial properties. These materials could provide additional functionalities to the host material (Nie et al. 2011; Hou et al. 2005; Jin and Jia 2014). Membranes prepared from these carbon-based new generation materials offer substantial advantages over conventional materials. These important features of carbon-based new generation nanomaterials can be easily integrated into different type of membrane and contribute to the superior removal ability for water contaminants such as solid particles, organic and inorganic compounds, macromolecular biomolecules and microorganisms (Nie et al. 2011; Hou et al. 2005; Jin and Jia 2014). The emergence of carbon nanotubes (CNTs) set light to on development the ideal membrane filters, because CNTs not only has the ceramic-like stability, but also the polymer-like flexibility and possible processibility. Further, CNTs supply excellent 1D nanochannel, which provide high flow rate characteristics to the membrane system with reasonably low pressures due to the atomic smoothness of the nano-sized channel, and the one dimensional single-file ordering of water molecules while passing through the

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membranes (Sen et al. 2004). The cytotoxic nature of CNTs prevents the accumulation of pathogenic biofilms on membrane surfaces, unlike the other polymer based membranes which provide more clean membrane surface. The two important advantages membranes modified with CNTs lead to low operating cost. And also, the ability to adjust the hydrophobicity of the membranes using CNTs creates significant advantages in water treatment systems based on the separation of molecules according to their polarity (Tiwari et al. 2008; Srivastava et al. 2004). The unique features of the newly emerged 2D graphene or graphene oxide described above offer an exciting chance to fabricate a fundamentally new class of membrane filters by stacking GO nanosheets (163). Graphene or graphene oxide has great flexibility and solution processibility such as CNTs. The membranes modified with graphene or graphene oxide has lead to the fabrication of the new generation of ultrathin, high-flux and energy-efficient membranes for water treatment process (Park et al. 2000). Recently, the fabrication of metallic, metal oxide and metal hydroxide nanofiber membranes or modification of polymer based nanofiber membranes with metallic, metal oxide and metal hydroxide nanomaterials is a feasible route to improve the stability of nanofiber membranes for harsh processes, enhance adsorption capacity and selectivity of nanofiber membranes to prevent accumulation of pathogenic biofilms, to offer robust antibacterial activity for microorganisms and gain catalytic/ photocatalytic activity for removal of water contaminants such as organic and microorganisms (Ma et al. 2017a, b; Lee et al. 2016a, b; Zhao et al. 2017a, b; Lu and Wang 2014). The metallic, metal oxide and metal hydroxide nanoparticles such as Ag, Pd, SiO2, TiO2, CuO, ZnO, Al2O3, Fe2O3, Fe3O4 and Fe(OH)3 are the most used materials for fabrication or modification of nanofiber membranes (Ma et al. 2017a, b; Lee et al. 2016a, b; Zhao et al. 2017a, b; Lu and Wang 2014). Zeolites, which consist of alumino silicate framework, exchangeable cations, and water within the pores, are added in fiber, film, and coating forms in membrane applications. Zeolites have different size of pores that lead to molecular sieves separation in membrane process. Moreover zeolites are nontoxic and very stable under membrane filtration conditions make them effective nanofiber materials for membrane process (Choi et al. 2016). The membrane applications in which materials such as polymers, precious metals and metal oxides, carbon based materials (Carbon nanotubes, fullerenes, graphene and graphene oxide), ceramic, zeolite, soluble drugs, biofilms and smart biological agents etc. used are shown in Table 6.1 and explained in detail below. One of the important applications in this area is the production of nanofiber membranes with the desired polarity. Especially, the wettability of the membranes is the most important driving force for the oily waste water separation process. Both superhydrophobic-superoleophilic (“oil-removing” type) and superhydrophilic-­ underwater superoleophobic (“water-removing” type) surfaces are suitable for these applications. An important application about this point was made by Wu and his colleagues. Hydrophilic properties of ceramic nanofibers and other polymer based membranes are oppressed due to existence of polar sites leading to surface hydroxyl. Scientists make great effort to produce hydrophobic ceramic nanofibers, including

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SiC, SiCNO, Al2O3 and TiO2, etc. For this purpose, Wu et al. modified the hydrophilic SiOC nanofibrous membrane with Pd particles and the obtained flexible and hydrophobic SiOC-xPd fibrous membrane with high mechanical stability, which are resistant to pH and temperature changes for water-oil emulsion separation application in harsh environment (Wu et al. 2017). They fabricated the hydrophobic ceramic nanofiber membrane through pyrolysis of electrospun polycarbosilane nanofibers. The SiO2 nanoparticles have hydrophilic character. Modifying the polymer-based membranes with these particles is a good idea for producing membranes with hydrophilic properties. Moreover the membranes modified porous SiO2 nanoparticles has higher porosity and mechanical strength. A polyvinyl acetate (PVAc)coated nylon 6/Silica (N6/SiO2) composite microfiltration (MF) membrane has high flux and antifouling properties was fabricated with a facile electrospinning technique by Islam and his colleagues for microfiltration of oil-in-water (O/W) emulsions (Islam et  al. 2017). Yang et  al fabricated a 3-aminopropyltriethoxysilane (APTES) modified Multi-wall carbon nanotubes (MWCNTs)-poly(vinylidene fluoride) (PVDF) nanofiber membranes (APTES-MWCNT/PVDF). They firstly functionalized on the surface of MWCNT with APTES and then directly decorated on poly(vinylidine fluoride) surface by dopamine copolymerizes. The poly(vinylidine fluoride) nanofiber membrane with hydrophobic character was converted the APTES-MWCNT/PVDF nanofiber membrane with superhydrophilic character by bio-inspired method. Another important contribution of modification of poly(vinylidine fluoride) membranes is that the APTES-MWCNT/PVDF nanofiber membrane has excellent stability durable oil-fouling repellency, which could be easily reused with a flux ratio up to approximately 900 LMH and excellent efficiency (>99%) (Yang et  al. 2017a, b). Qing et  al. fabricated a superhydrophobic PTFE@PVA hybrid nanofibrous membrane for oil/water separation by using electrospinning procedure. The experimental results showed that PTFE@PVA hybrid nanofibrous membrane was resistant to pH changes and the membrane exhibited a strong mechanical strength of 19.7  MPa. In addition to these good features, the resistance of the nanofiber to vibration was tested and the nanofiber in the membrane exposed to high vibration was still intact (Qing et al. 2017). A different application which brought a different perspective to the two applications explained above was done by Obaid and his colleagues. In this study, the authors produced a new PVDF-TEA membrane with superhydrophilic property from superhydrophobic poly(vinylidine fluoride) electrospun nanofiber membrane. For this purpose, the PVDF-TEA membrane was produced by hydrothermal treatment in presence of TEA and water. The modifications strongly change the physicochemical features of the membrane, which turns into the membrane from highly hydrophobic to be superhydrophilic under-oil when wetted with water (Obaid et al. 2017). The PVDF-­ TEA membrane showed a higher outstanding flux (20664 L m−2 h−1) than pristine membrane by numerous times for the separation of the emulsion. The experimental results showed that the PVDF-TEA membrane as modified membrane could separate an enormous amount of oil from water with a 99% efficiency and lowest energy consumption (Obaid et  al. 2017). Cao et  al. successfully fabricated a stellate poly(vinylidene fluoride) (PVDF)/polyethersulfone (PES) microsphere nanofiber

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membrane by using electrospinning method. In this study, they modified poly(vinylidine fluoride) membrane with polyethersulfone and succeeded in imparting good thermal properties and special wetting properties. The fabricated PES/ PVDF membranes provided excellent separation performance for oil/water mixture (Cao et al. 2017). The ability to control the different features of processes and systems with an externally applied effect has attracted the interest of humans throughout history and will continue to attract. These processes and systems are used for different laboratory and industrial applications and called as “smart” applications. Lately, numerous nanofiber membranes called as smart membranes have been fabricated that respond to applied external effects such as pH, temperature, electricity, light irridation, etc. and their wettability characteristics vary depending on these external effects. An example application for these smart membranes was made by Cheng and his colleagues. They fabricated smart poly(vinylidene fluoride)-graft-poly(acrylic acid) (PVDF-g-PAA) tree-like nanofiber membrane by electrospinning method. In this application, the wettability and conformation of the (PVDF-g-PAA) tree-like nanofiber membrane varies depending on the pH of the aqueous phase. Most importantly, oil/water separation using gravity was achieved by switching the pH of the medium. It was believed that the switchable membranes will take their place in very important applications such as water purification, oil recovery and some separation systems (Cheng et al. 2017). The other important application on smart (switchable) membranes was conducted by Janus nanofiber membranes prepared from hydrophilic polyacrylonitrile electrospun nanofiber (PANEN) membrane and single-side hydrophobic carbon nanotube (CNTs). Carbon nanotubes (CNTs) with excellent properties have been used in the modification of the different type of nanofiber membranes. The CNTs@PANEN membrane showed asymmetric wettability from PANEN and CNTS sides: The hydrophilic PANEN side provided underwater oleophobicity, and the hydrophobic CNTs side provided underwater oleophilicity. As a result, the CNTs@PANEN membranes showed a switchable oil/water separation application in different usage modes: effective oil-in-water emulsion separation by using the PANEN side and water-in-oil emulsion separation by using the CNTs side (Jiang et al. 2017). In addition to the switchable property of CNTs@PANEN nanofiber membranes, the modification of PANEN with CNTs could assist the water flux via the facilitated water separation on the permeate side promising for water remediation applications (Jiang et al. 2017). A different innovative approach about smart membranes was made by Ma and colleagues. They synthesized a dual pH-and ammonia-vapor-responsive SNP/ DA-TiO2/PI membrane for oil-water separation. They successfully fabricated the membrane dip-coating electrospun polyimide (PI) in silica nanoparticles (SiNPs) and decanoic acid (DA)-TiO2. The new membrane had superhydrophobicity character in air and superoleophilicity character in neutral aqueous medium (e.g., at pH 6.5). However, the membrane gained hydrophilic and superoleophobic character in basic aqueous medium (e.g., at pH 12), cause only water permeation throughout oil-water separations. In addition, the SNP/DA-TiO2/PI showed high permeates flux and high stability (Ma et  al. 2017a, b). Nanofiber membranes (NFMs) provides

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innovative and effective water treatment medium for highly efficiently remove particles (even 0.1  mm particles) from water via high-performance microfiltration, ultrafiltration and nanofiltration applications. The application of nanofiber membranes (NFMs) in the microfiltration, ultrafiltration and nanofiltration applications for water treatment process requires the nanomaterial modification possess suitable strength, fiber diameters, porosities, thickness, permeability, and a smooth surface. Hence, these features of the NMs for the effective membrane filtration must be carefully controlled. The important parameters, which affect the microfiltration performance, are fiber diameters and porosities and thicknesses of membranes. For this purpose, Wang et al. explored the effects of fiber diameters, porosities and thicknesses of membranes on high-performance microfiltration applications. Due to the diameters, porosities and thicknesses of electrospun polyacrylontrile nanofibers could be easily controlled upon changing the amounts of spinning solutions. The polyacrylontrile as the model polymer was used. They fabricated nine types of polyacrylontrile nanofiber membranes at 60  °C in different size (between 150 and 750 nm) by a facile hot-pressing method. For the first time in literature, they effectively controlled the membrane porosity by a hot-pressing method and then they systematically searched the relationships between membrane features and microfiltration performances. It was proved that when the membrane porosity can be decreased from 86% to 34%, an important improvement in the rejection fraction from 0.2% to 100% for 0.2 mm particles was obtained. In addition, when compared to conventional microfiltration procedure, these membranes provided significantly higher flux and substantially lower degrees of fouling without distinguishably sacrificing particle rejection fractions (Wang et al. 2017a, b). Polyethylene terephthalate (PET) is a material with a wide range of uses in the packaging of water and other extensive used materials create high amount of plastic waste often with limited incentive for recycling. Hence, repeated use of poly(ethylene terephthalate) is a important task. Zander et  al. produced recycled poly(ethylene terephthalate) nanofibers from poly(ethylene terephthalate) plastic bottles and used for removal of latex beads having sizes ranging from 30 to 2000 nm by microfiltration system. In this filtration process, more than 99% of the latex beads as small as 500  nm were removed. They modified the recycled poly(ethylene terephthalate) nanofibers with quaternary ammonium and biguanide biocides to reduce biofouling (Zander et al. 2016). The polyethersulfone (PES) electrospun nanofiber membranes (ENMs) has an important place for water treatment procedures and used commercial microfiltration (MF) and ultrafiltration (UF) membranes. Therefore, Bae et al. explored an optimum electrospinning fabrication condition of the polyethersulfone membrane to obtain improved mechanical property and surface roughness. They used the different concentrations of polyethersulfone prepared in N-methyl-­ pyrrolidinone as a solvent for fabrication of polyethersulfone (PES) electrospun nanofiber membranes (ENMs). The fabricated polyethersulfone electrospun nanofiber membranes had high mechanical strength (tensile strength: 11.0 MPa), a homogeneous pore size distribution (0.4175 μm), 8 times higher flux performance than commercial products. Moreover, the electrospun nanofiber membranes synthesized by using NMP solvents had more rejection and flux recovery capability than the

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electrospun nanofiber membranes prepared by DMF solvents because of the low roughness and annealed fibers (Bae et al. 2016). Aslan et al. fabricated novel tubular nanofiber (TuEN) membranes by collecting nanofibers on a hollow braided rope for first time in literature. TuEN membrane had a very good fiber structure in terms of porosity, hydrophilicity, distribution of pore size, cross linked nanofiber structure and cross-section thickness. As compared to other microfiltration membranes, the TuEN membranes showed high water fluxes in even low vacuum pressures, relatively effective removal of total organic carbon (29%), turbidity (95%) and UV254 (45%) from different type of water samples. It is believed that tubular nanofiber membranes will be an important application in future for water and waste water treatment areas (Aslan et al. 2016). The nanofibrous membranes can be used as microfiltration membranes. This, upon further modification, reduces the surface pore sizes further and has been explored for the ultrafiltration and nanofiltration applications. In order to solve the important negation of conventional ultrafiltration membrane applications such as low flux rate and surface fouling mentioned upper sections. Many methods are used follow as: (1) change of the membrane’s surface features through plasma treatment, oxidation, and hydrolysis; (2) addition of nanoparticles in the polymer solution before membrane production and (3) application of a hydrophilic top coating layer on the ultrafiltration membrane surface (Bahmani et  al. 2017). Among them, the hydrophilic coating layer is the best method because it down to the lowest levels the fouling problem by obstructs adsorption on the surface (Wang et  al. 2005). Electrospun nanofiber membranes play a major role in increasing the efficiency of ultrafiltration methods. However, in these systems where Electrospun nanofiber membranes are used, the tendency of the membranes to a rapid fouling with significant loss of flux limits the usability of UF applications. Hence they are combined with a thin film as coating, i.e., as a thin film composite (TFC) membrane. These ultrafiltration-thin films composite (UF-TFC) membranes are fabricated in the form of a triple sheet consist of an untreated microfibrous substrate, an electrospun nanofiber for the middle sheet and a barrier sheet. Bahmani et al. produced a new high-­ flux thin film composite (TFC) ultrafiltration membrane consist of an electrospun nanofibrous scaffold, a polyethylene terephthalate (PET) substrate as support, and a polyacrylonitrile (PAN) coating layer to remove arsenate from contaminated water. The flux ratio and contaminant rejection were compared to a conventional ultrafiltration (UF) membrane. Experimental results proved that the thin-film composite membrane had 172–520% higher flux ratio than the ultrafiltration membrane. Moreover, the thin-film composite membrane had 1.1–1.3 times more arsenate ions rejecting performance than the ultrafiltration membrane. The 3D porosity of nanofibers in thin-film composite membranes delayed the fouling of thin-film composite membrane (Bahmani et al. 2017). CNTs supply excellent 1D nanochannel, which provide high flow rate characteristics to the membrane system with reasonably low pressures mentioned upper sections. By using this feature of carbon nanotubes, You et al. (2013) fabricated a high flux low pressure thin film nanocomposite ultrafiltration membrane as called high performance thin film nanocomposite (TFNC) consist of a hydrophilic

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nanocomposite poly(vinyl alcohol) (PVA) barrier layer and a porous polyacrylonitrile (PAN) electrospun nanofibrous supporting layer. The interior of the PVA barrier was modified with the surface oxidized multi-walled carbon nanotubes (MWNTs) to evolve the water transportation. The TFNC membrane was produced by using electrospinning technique and used for treatment of waste oily water. The results obtained show that the modification of PVA barrier layer with MWCNTs could evolve the water flux significantly, which demonstrated that more effective water channels were produced in the nanocomposite barrier layer with this modification (Sánchez 2017). The PVA–MWCNT/PAN TFNC (10 wt.% MWNT) membrane provide very high water flux (270.1 L m−2 h−1) with great removal percentage (99.5%) even at very low feeding pressure (0.1 MPa) (185). Improving the biological performances of membranes is an important area of the membrane based filtration applications. For the first time, Nie et al. modified the polysulfone (PSF) and polyethersulfone (PES) membranes with aramid nanofiber (ANF) to improve the filtration and biological efficiency of the ultrafiltration membranes. ANF is completely stable and non-dissolvable in water, which it can be used as an ideal modifier for producing hydrophilic characteristic dominant composite membranes and also the produced membranes had more porous structures, improved antifouling properties, improved blood compatibility for limited protein adsorption and improved adsorption of small molecular creatinine toxins in dialysis practices. It was believed that hydrophilic nanofibrous ANF modifier will be of promising potential for the production of new type of ultrafiltration membranes used water purification and hemodialysis applications (Nie et  al. 2017). Vanangamudi et  al. fabricated Janus nanofiber membranes by using two-step method, i.e., consecutive electrospinning of hydrophilic nylon-6,6/chitosan nanofiber blend and conventional casting of hydrophobic poly(vinylidene difluoride) (PVDF) dope solution for reversed protein fouling ultrafiltration. The surface properties, permeability, and reverse protein fouling ability of this membrane was compared with the the pure PVDF and PVDF/nylon-6,6 membranes. The combining of the cast layers and nanofiber caused changed pore regulation offering about 93% removal of bovine serum albumin (BSA) proteins as the model organic contaminant with a permeance of 393 L m−2 h−1 bar−1 in cross-flow filtration studies; while the PVDF comparison only had a BSA removal of 67% and a permeance of 288 L·m−2·h−1·bar−1. The PVDF/nylon-6,6/chitosan membrane showed 78% decrease in the irreversible fouling and high fouling propensity with 2.2 times higher reversible fouling, when compared to the PVDF benchmark after 4 h of filtration with BSA foulants (Vanangamudi et  al. 2017). Generally, hydrophilic membrane, which has a high surface energy, shows an affinity for water because of the formation of hydrogen-bonds with water. Hydrophilic surface push the hydrophobic species such as hydrocarbons, oils, surfactants etc. In recent years, scientists has been focused to production of the membranes with high hydrophilic character by forming micro-nano structures on surface for oil-water separation, which lead to low oil adhesion results in super oleophobic surfaces. Prince et al. provide an easy procedure to increase the hydrophilicity, permeability and selectivity of the polyethersulfone (PES) hollow fiber ultrafiltration (UF) membrane by using carboxyl, hydroxyl and amine modified graphene attached

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poly acrylonitrile-co-maleimide (G-PANCMI). They finally subjected the new PES-­ G-­PANCMI membrane a continuous 8  h filtration test for separation of oil from water by ultrafiltration method. The results obtained from these tests showed that when compared with polyethersulfone membrane, the water contact angle (CAw) of the PES-G-PANCMI membrane was lower about 64.5% while, the oil contact angle of PES-G-PANCMI membrane was higher about 158%. Similarly, the LEPoil increased 350% from 50 ± 10 kPa of the control PES membrane to 175 ± 25 kPa of PES-G-PANCMI membrane. The test results proved that the G-PANCMI has an effective role in improving the hydrophilicity, permeability and selectivity of the polyethersulfone membrane (Prince et al. 2016). Most conventional nanofiltration (NF) and traditional reverse osmosis (RO) membranes have been produced in thin film composite (TFC) structure which made of three essential layers (i) a nonwoven backing material, (ii) a microporous mid-­ layer (prepared with phase inversion method) and (iii) a thin selective barrier layer. Recently, change of the ultrafiltration (UF) middle layer in conventional thin-film composite (TFC) membranes by NMs was applied for formation of the thin-film nanocomposite (TFNC) membranes, which supply an enhanced flux over thin-film composite membranes used in nanofiltration (NF) process. When nanofibrous membranes were modified with a thin barrier film they show high nanofiltration efficiency with less fouling. The basic performance of each layer in three-layered thin film composites can be explained as follows: the barrier layer for flow rate control and solute rejection; the ultrafiltration membranes for control the resistance to the permeation flux and support the thin barrier layer; and finally the base support membranes of nonwoven microfibrous support for mechanical strength. Among these three layers, the top barrier layer has a key role on the separation of the impurities and fouling rate (Sundarrajan et al. 2013). Hence, modification of the nanofibers in used nanofiltration membranes with different types of additives is an important issue to control the flux rate, improve the mechanical strength, separation performances and decrease the fouling rate. The nanocomposite format of thin layer improving the water transport ability, the great open pore structure and the low hydraulic resistance of the nanofibrous support provide the enhanced flux in TFNC membranes (Mahdavi and Moslehi 2016). By considering these important facts, Mahdavi and Moslehi fabricated a new type of thin film nanofibrous composite nanofiltration membranes (PET-TFNC-NF) based on polyethylene terephthalate (PET) self-support nanofibrous mats for salt rejection in water samples. In the first step, the two-axial electrospinning technique was used to produce poly(ethylene terephthalate) nanofibrous mats with small average fiber diameter and then reverse interfacial polymerization (IP-R) technique was applied to obtain TFNC-NF-­ membranes. They also prepared the thin film composite (TFC) nanofiltration membrane with the same experimental conditions based on polyethersulfone ultrafiltration membrane to compare the filtration performance of PET-TFNC-NF membrane with the thin-film composite nanofiltration membrane. Results showed that the TFNC nanofiltration membrane had higher removal efficiency for of salt and four times improved water flux than the thin-film composite nanofiltration membrane (Mahdavi and Moslehi 2016).

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Nanofiltration membranes with high permeability are usually desired in removal of the dissolved contaminants because of the environmental and energy concerns. In order to fulfill this requirement, Soyekwo et al. produced an ultrathin crosslinked-­ PEI nanofiltration membrane by using surface modification of ultrafine cellulose nanofiber (UCN) membrane via interfacial polymerization. In this study, narrow permeation channels that lead to high flow rate of water (water flux rate of 32.7 L m−2 h−1 bar−1 is an higher value previously reported similar nanofiltration membranes) was obtained the growth of the crosslinked-PEI layer in the free spaces of interconnected nanoporous microstructure on hydrophilic UCN membrane. The ultrathin crosslinked-PEI nanofiltration membrane had positively charged and supply effective removal of organic and inorganic species in water samples. It was believed that this process leads to the development of highly-permeable nanofiltration membranes for fast water treatment and effective separation of small molecules (Soyekwo et al. 2017). Flux rates of nanofiltration are related with thickness of selective layer in a nanofiltration medium. The applicability potential of a range of 2D materials have been proved to obtain high performance selective layers with great efficiencies for water treatment process. More scientist have been focused on graphene and/or graphene oxide (GO) sheets as a promising type of materials for water purification to produce nanofiltration membranes. Graphene and graphene oxide GO sheets have gained important attention because of the ultrathin 2D structure and more importantly, the narrow inter-sheet nanochannels in the stacked lamellar membrane (with spacing around 1 nm). These nanochannels in GO sheet layer, which has the thickness ranging from tens to hundreds of nanometers, play a important role to remove species with sizes larger than 1 nm from water (Wang et al. 2017a, b). Wang et al. simply fabricated a hot-pressed electrospun polyacrylonitrile (PAN) nanofiber membrane with graphene oxide (GO) sheets to obtain a continuous and crack-free layer. The resulting PAN-rGO nanofiltration membrane could remove about 90% of MgSO4 with high water flux. It was believed that the reported application provides many benefits to research groups working on different types of membrane applications of 2D materials. And also, the hot-pressed electrospun nanofiber membranes could be usually used as an innovative kind of platform to support various 2D sheets for highly effective and cheap removal of contaminants from water (Wang et al. 2017a, b). Wei et  al. was produced a novel hollow fiber membrane (HFM) that consists entirely of carbon nanotubes (CNTs) for the first time to remove the small and trace contaminant molecules. When compared with the most of commercial membranes used in nanofiltration process, the produced CNT-HFMs showed the 10−100 times higher permeation flux of about 460 ± 50 L m−2 h−1 at a low pressure differential of 0.04 MPa across the membrane. In addition, the most important contribution of the CNT-HFMs for water treatment process is that they can be in situ electrochemically regenerated after adsorption saturation (Wei et al. 2014). Water purification or treatment systems have most significant role for ensuring that the highest discharge limits of metal ions are not exceeded and a range of technologies have been applied for recovery and removal of metal ions from waters (Zhao et al. 2017a, b; Fu and Wang 2011). The working principle of barrier-type

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membranes used in microfiltration, ultrafiltration, nanofiltration and osmosis filtration process are based on sieving mechanism, which permit water molecules to pass through in membrane while sieving dissolved and undissolved species (i.e., salts, organic contaminants bacteria and viruses). Hydrodynamic diameters of metal ions are ordinarily less than 20 Å and they are sieved by reverse osmosis membranes. Hence, barrier-type membranes are not selective for recovery of specific heavy metal ions from waters. Among the numerous applications usable, ion exchange processes are perhaps the most effective way to remove or recover specific metal ion pollutions from waste waters due to their superior treatment capacity, excellent removal efficiency and quick kinetics. The selective recovery of metal ions from waste water is crucial especially due to differences of their toxicity or reuse value. For special industries, the selectivity of separation equipment for a targeted metal ion undoubtedly has the most important part for defining the economic and technical performance of the separation process. A range of studies have been assumed to produce new ion-exchange media for only single-component ion exchange (Chitpong and Husson 2017a, b; Jiang et al. 2017; Yang et al. 2017a, b). But, most waste water effluents born of industries contain two or more metal ions. Hence, it is necessary to work binary-or multicomponent ion exchange to evaluate the competing influence of these components for ion exchange sites. Chitpong and Husson produced a new polyelectrolyte modified nanofiber-based ion-exchange membranes with high capacity for heavy metal recovery from impaired water taking into account the reasons explained above. The membranes, which fabricated by grafting poly(acrylic acid) (PAA) and poly(itaconic acid) (PIA) to cellulose nanofiber mats, had selectivity for Cd over Ni and Ca at constant pH due to different hydration energies and ionization potentials. Single-­ component ion-exchange isotherms were exhaustively studied by the Langmuir model, and maximum capacities of PIA-modified membranes were found as 220 mg g−1, 52 mg g−1 and 33 mg g−1 for Cd, Ni and Ca, respectively. The capacities are comparable to traditional resin-based ion-exchange membranes. This work proved that nanofiber membranes offer a high capacity and superior productivity medium for selective removal of heavy metal ions from impaired waters (Chitpong and Husson 2017a, b). In another study, same authors used polyacid functionalized cellulose nanofiber membranes for removal of cadmium ions from impaired waters. The membranes offered superior capacity and productivity for cadmium ions. In this reported study, an electrospinning and thermal-mechanical annealing methods in two step were used for preparation of the cellulose acetate nanofiber membrane. Then ion-exchange membranes were obtained with the surface modification of cellulose acetate nanofiber membrane. The surfaces of poly(glycidyl methacrylate)cellulose acetate nanofiber was modified with poly(acrylic acid) (PAA). PAA molecular weight was directly effective on membrane permeabilities as a result of chain swelling in water, while PAA molecular weight had no effect on Cd ion exchange capacities. Ion-exchange isotherm was checked by the Langmuir model, and maximum capacity of polyacid functionalized cellulose nanofiber membrane for cadmium ions was found as 160 mg g−1 at constant pH. The capacity was comparable to traditional ion-exchange mediums (Stottmeister et al. 2003). Pan et al.,

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fabricated anion exchange membranes from hot-pressed electrospun poly(2,6-­ dimethyl-­1,4-phenyleneoxide) /Silicondioxide hybrid material (QPPO–SiO2) nanofibers for acid recovery from simulated iron polishing waste solution containing 1 mol L−1 HCl and 0.225 mol L−1 FeCl2. The performance parameter showed that the fabricated hot-pressed electrospun QPPO–SiO2 membrane offered about 7 times higher permeability and 3 times higher selectivity than commercial DF-120 membrane, which has permeability of 0.005–0.009 m h−1 and selectivity of 18.5–23.5 (Pan et al. 2015). Among the several membrane systems produced by different methods, nanofiber membranes have receive extensive concern in the recent years as potential membranes because of the their ideal properties for osmosis based membrane process (Reverse osmosis (RO), forward osmosis (FO), pressure-retarded osmosis, (PRO) and membrane distillation (MD) process). Even though osmotically driven membrane applications have been proven to be possible for many applications, the development of suitable and important applications of them for industrial process is still not fully realized due to drawbacks of these membrane processes mentioned upper sections. The absence of an adequately fabricated membrane has been the great challenge that inhibits engineered osmosis (EO) membranes (e.g., forward osmosis, pressure-retarded osmosis, direct osmosis). High solute removal, high mechanical strength and competitive permeation water flux of membranes are main requirements for osmotic processes. Re-engineering the support layers of forward osmosis (FO) and pressure-retarded osmosis (PRO) membranes is important for making these applications commercially available. Real-world applications of forward osmosis and pressure-retarded osmosis for water treatment process will request membranes to with stand important stresses. The first forward osmosis sea water desalination plant of world have been lately found and employed at Al Khaluf in Oman (Dabaghian and Rahimpour 2015). But, internal concentration polarization (ICP), which importantly decreases the driving force for the water transport, causes a significant problem in forward osmosis process. The ratio of ICP is related with the porosity, tortuosity and thickness of the support layer of the membrane. Particularly, valuable contributions of nanoparticle mixed matrix membranes (MMMs) on the minimization of ICP problem and improvement of properties of pressure retarded osmosis (PRO) and forward osmosis (FO) membranes have been newly reported by many scientists. Previous experimental studies proved that the hydrophilic bulk and surface modification of membranes with different nanofiller such as CNTs, TiO2, SiO2, zeolite, and so on significantly solve the ICP problems and low water flux and improve the membrane properties of forward osmosis membranes. Moreover, it was proved that these forward osmosis and pressure-retarded osmosis membranes modified with nanofiller show better performance than commercial membranes. A number of studies have been carried out to use these important properties of the nanofiller in forward osmosis and pressure-retarded osmosis membrane process. Thin film composites (TFC) modified with nanofiber used forward osmosis and pressure-retarded osmosis membranes have showed promising for effective application in comparison to commercial forward osmosis membranes. Dabaghian and Rahimpour fabricated

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cellulose triacetate (CTA) membranes including carboxylated carbon nanofibers (CNFs) by using phase inversion procedure for the forward osmosis (FO) process. They functionalized CNFs with carboxyl groups (COOH) to impart hydrophilic property. Then, they added the different contents of carboxylated CNFs (0.25, 0.5 and 1 wt%) in the casting solution to enhance the forward osmosis efficiency of membrane. They checked the forward osmosis experiments by using 10 mM NaCl solution as a feed solution and 1 M NaCl solution as a draw solution in both orientation of membrane. Moreover they used this forward osmosis membrane for sea water desalination. The new membrane showed excellent efficiency in term of low solute diffusion, high water flux and higher water flux than CTA membrane (Dabaghian and Rahimpour 2015). The application on usability of carbon nanofibers for production of forward osmosis membrane was conducted by Dabaghian et al. They produced highly porous carbon nanofiber (CNF)/cellulosic membranes by using carboxylic and amine functionalized CNFs and used for water desalination by the forward osmosis (FO) process. Thanks to this modification, the porosity and hydrophilicity of cellulosic membranes were importantly improved. The modification of membrane with amine functionalized CNFs showed high forward osmosis flux (18  L m−2) and low reverse solute flux (~0.5 g m−2 h−1). The water flux of obtained forward osmosis membrane was twice as high as that the neat cellulosic membrane two times. Moreover, reverse salt flux of the amine functionalized CNF membrane was very low compared to the commercial cellulose triacetate (CTA) membrane that these were the most promising results for future applications of CNFs modified forward osmosis membrane in seawater desalination process (Dabaghian et al. 2016). Obaid et  al. fabricated a new amorphous silica nanoparticle-incorporated poly(vinylidine fluoride) electrospun nanofibers as efficient membranes for forward osmosis (FO) desalination. They investigated the effect of the silica nanoparticle content on salt rejection and water flux by adding 0, 0.5, 1, 2, and 5 wt% SiO2 nanoparticles in electrospun nanofiber membrane. The performance of the amorphous silica nanoparticle-incorporated poly(vinylidine fluoride) electrospun nanofibers was checked with forward osmosis application. In this application, they used fresh water as a feed and different brines as draw solution (0.5, 1, 1.5, and 2  M NaCl). The results showed that the membrane had 0.5 wt% of silica nanoparticle displayed water flux of 83 L m−2 h−1 and salt rejection of 99.7% with 2 M NaCl draw solution. The authors put forwarded that the introduced membranes were promising for forward osmosis desalination technology (Obaid et al. 2016). Electrospinning is an effective and common method to fabricate nanofiber supports for thin-film composite membranes. Tian et al. explored the usability of electrospun polyvinylidene fluoride (PVDF) nanofibers as substrates to obtain high-performance forward osmosis (FO) membrane. They successfully synthesized polyamide thin films by interfacial polymerization directly on two electrospun PVDF nanofiber substrates having different pore size and surface roughness as surface characteristics. They characterized the surface structure, water permeability and salt rejection of fabricated thin film composite (TFC) forward osmosis membranes by a series of observation containing SEM image measurements, XPS

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characterization and separation property experiments. The experimental results showed that the synthesized thin-film composite membranes achieved a water flux of 30.4 L m−2 h−1 when the active layer was canalized towards the 1.0 M NaCl as draw solution while the ratio of reverse salt flux to water flux was accomplished as low as 0.21 g L−1. The obtained results proved that electro-spun nanofiber membranes had good potential as substrates for preparation of forward osmosis membranes (Tian et  al. 2013). Maqsud et  al., applied the electrospinning fabrication method to fabricate a robust and high performing thin-film composite membrane for forward osmosis by using poly(ether sulfone) (PES)-based nanofiber nonwoven membrane from E.I. du Pont de Nemours and Company (Du Pont) as a commercially available support. The DuPont polyethersulfone nanofiber, which utilized to support a polyamide selective layer synthesized by in situ interfacial polymerization, showed better strength than typical electrospun nanofiber. Further, The DuPont polyethersulfone thin-film composite membrane was examined in forward osmosis and found to create one-tenth the reverse solute flux and twice the water flux compared to a commercially available TFC-FO membrane (Chowdhury et  al. 2017). Nylon 6,6, polysulfone (PSu) and polyacylonitrile (PAN) are commonly used for preparation of thin film composite-­forward osmosis membranes (TFC-FO). Thin film composit pressure-­retarded osmosis (TFC-PRO) membranes because of their low permeability resistance and favorable wettability (205). However, these hydrophilicity forward osmosis and pressure-retarded osmosis nanofibers underwent the puffiness degree, which lead to weak interactions between fibers junction in during osmosis process. Hence, the using of hydrophobic nanofibers is a good and effective way to prepare forward osmosis and pressure-retarded osmosis membranes. Chi et al., provided an innovative interfacial polymerization (IP) procedure for fabrication of a novel thin film composite (TFC) forward osmosis (FO) membrane supported by hydrophobic polyimide (PI) microporous nanofiber membrane. For fabrication of TFC-FO PI nanofiber membrane by IP synthesis procedure, they used m-phenylenediamine (MPD) as aqueous phase monomer, ethanol as aqueous phase co-solvent and trimesoyl chloride (TMC) as organic phase monomer (Chi et al. 2018). Forward osmosis membranes produced by phase inversion procedure have a tortuous sponge-like pore structure in the support layers, which is the big obstruction to increasing water flux. To solve this obstruction, Song et al. produced a new nanocomposite forward osmosis membrane (NC-FO) by using a scaffold-like nanofiber support layer that provide important advantages compared to conventional sponge-­ like support layers such as high porosity, low tortuosity and pretty thin thickness. The wonderful characteristic of the nanofiber support layer provided direct routes for water and salt diffusion lead to elimination the ICP bottleneck. Polyethersulfone (PES) nanofiber was used for the fabrication of scaffold-like nanofiber support by electrospinning method (Song et al. 2011). The pressure-retarded osmosis process is a novel application which produces green electrical energy by using semi-­ permeable membranes. However, the lack of suitable membranes for pressure-­ retarded osmosis process, which mentioned reasons mentioned above, is a major challenge. Hence, scientists have been focused on the fabrication of the suitable pressure-retarded osmosis membranes. Hoover et  al. fabricated a thin-film

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composite membranes consist of electrospun polyethylene terephthalate nanofibers, a phase separation formed microporous polysulfone layer, and a polyamide selective layer obtained by interfacial polymerization. They used this new thin film composite membrane for forward osmosis and pressure-retarded osmosis applications with water permeability of 1.13 L m−2 h−1 bar−1 and salt permeability of 0.23 L m−2 h−1. The modification of the support layer with electrospun fibers improved membrane resistance to delamination at high cross-flow velocities (Hoover et al. 2013). Tian et al., produced a new thin film composite (TFC) pressure-retarded osmosis membrane composed of a tiered structure of polyetherimide (PEI) nanofibrous support consolidated by functionalized multi- walled carbon nanotubes (f-CNTs) and an ultrathin polyamide-based selective top skin layer. The tiered support was made by a fine and a coarse PEI nanofiber layers. The thin finer fiber modified with f-CNTs provided the improved mechanical stability in the polyamide selective layer for high hydraulic pressure in the pressure-retarded osmosis process. The newly fabricated PRO membrane was standable a trans-membrane pressure till 24 bar and produce a peak power density about 17.3W m−2 at 16.9 bar using synthetic sea water brine and deionized (DI) water as the draw and feed solutions. Moreover, this membrane could produce a stable power density of 15.070.5 W m−2 for a test period of 10 h (Tian et al. 2015). A different nanofiber supported thin-film composite membrane fabricated and used as pressure-retarded osmosis and forward osmosis membranes by Bui and McCutcheon. To fabricate the membranes, polyacrylonitrile nanofibers linked onto a polyester nonwoven fabric layer by electrospining method and then interfacial polymerization procedure was used for the formation of polyamide (PA) on polyacrylontrile nanofibrous supports. The new membrane generated an equivalent peak power density about 8.0 W m−2 for hydraulic pressure of 11.5 bar under 0.5 M NaCl as draw solution and deionized water as feed solution (Bui and McCutcheon 2014). The first attempt for usability of electro-spun nanofiber membrane in membrane distillation (MD) was made by Feng et al. in 2008. They fabricated a polyvinylidene fluoride nanofiber membrane to obtain drinking water from a saline water of NaCl concentration 6 wt.% by air-gap membrane distillation. This new application may shed light on the development of the membrane distillation process to challenge with conventional desalination processes such as reverse osmosis and distillation. The flux of polyvinylidene fluoride nanofiber membrane is comparable with commercial microfiltration membranes (5–28  kg m−2 h−1 at temperature differences ranging from 25 to 83 °C. Moreover, the membrane was intact for many days of working (Feng et  al. 2008). The rough nano sized surface of nanofiber supply improved hydrophobicity that is ideal for the membrane distillation applications. Nanofiber membranes did not have performance that can be used for a long time, which is one of the most important problems. To solve this problem and produce robust nanofiber membranes, up to now, scientists make an effort at excessive amounts. Superhydrophobic membranes are fabricated as suitable membrane distillation membranes. Because they provide less wetting problem, great salt rejection, enhanced water vapor and flow improved liquid entry pressure (LEP). Modification of nanofibers with different materials such as silica, graphene, graphene oxide (GO)

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carbon nanotubes (CNTs) and so on lead to formation of superhydrophobic nanofiber membranes (Park et al. 2016; Lee et al. 2016a, b; Woo et al. 2016). Graphene is of particular interest in membrane distillation processes because of its hydrophobic character, selective sorption of water vapors, and anti-fouling features (Woo et al. 2016). The combination use of the wonderful features of nanofibers and graphene offer extra attribution to the membranes like additional roughness and hydrophobicity. Woo et al. fabricated a graphene-enhanced robust and superhydrophobic electrospun nanofiber membrane for water desalination via air gap membrane distillation (AGMD). They incorporated to different concentrations of graphene (0–10 wt%) in/ on electrospun polyvinylidene fluoride-co-hexafluoropropylene (PH) membrane to fabricate the superhydrophobic electrospun nanofiber membrane (ENM). They announced that modification of the electrospun membrane with optimal concentration of graphene significantly improved the structure and features of membrane. The membrane had porosity more than 88%, contact angle more than 162° (superhydrophobic), and high liquid entry pressure (LEP) more than 186  kPa. These important features cause a superior and steady air gap membrane distillation (AGMD) flow of 22.9 L m−2 h−1 and wonderful salt rejection (100%) for 60 h of operation by utilizing 3.5 wt% NaCl solution as feed (Woo et al. 2016). Plasma treatment modification method is an important and effective way to modify the surface features of membranes such as the balance of hydrophilicity/hydrophobicity and surface free energy. Various gas plasma treatment procedures (oxygen, argon, methane and tetrafluoromethane) have been used for this purpose. Especially, tetrafluoromethane (CF4) plasma modification allows etching, replacement or polymer modification for membranes, improving their anti-wetting features. Moreover, CF4 plasma can modify fluorinated polymer surfaces displaying attractive features of fallen surface free energy and fallen coefficient of friction with enhanced surface wettability. Supplying omniphobicity to the electrospun nanofiber membranes (ENMs) is an important way to use their extremely porous and multi-layered structure with relatively rough surface. A CF4 plasma-modified omniphobic poly(vinylidene fluoride) (PVDF) electrospun nanofiber membrane was produced for air gap membrane distillation (AGMD) by Woo et al. The air gap membrane distillation capability of the membrane was checked by using real reverse osmosis (RO) brine obtained from coal seam gas (CSG) water that was added with surfactant as feed solution. Air gap membrane distillation performance offered steady normalized flow rate (primary flow rate of 15.3 L m−2 h−1) and rejection ratio of 100% even with the 0.7 mM sodium dodecyl sulfate surfactant concentration in the RO brine from CSG obtained water feed, while addition of 0.3 mM of surfactant caused damage on commercial PVDF membrane. It was believed that the fabricated omniphobic membrane offer an effective process to obtain clean water from challenging waters include organic contaminants and high salt (Woo et al. 2017). Titania (TiO2) is considered as an encouraging material for different environmental applications, since it has comparatively low cost, wonderful photocatalytic capability, exceptional photostability, and low toxicity. TiO2 is an important material to fabricate superhydrophobic nanofiber membranes and can be changed the porosity, contact angle, fiber size and LEP properties of membranes due to its broad

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pore size and high porosity. Some of these applications are summarized below. Lee et al. fabricated polyvinylidene fluoride-co-hexafluoropropylene(PH) modified fluorosilane-coated TiO2 nanocomposite electrospun nanofiber to obtain highly hydrophobic distillation membranes. They obtained the the highest liquid entry pressure (LEP) of 194.5 kPa with a membrane consist of 10% PH and 10% TiO2 and the largest contact angle of 149° (highest surface hydrophobicity) with a membrane consist of 20% PH and 10% TiO2. Moreover, when compared commercial membranes and electrospun nanofiber membranes without TiO2, it was proved that the electrospun nanofiber membranes include 10% TiO2 showed better flux and stable salt rejection (Lee et  al. 2016a, b)). Fan et  al. produced a membrane distillation (MD) membrane consisted of TiO2 nanofibers by using vacuum filtration and fluorination modification. They used this membrane for desalination of artificial seawater with 3.5 wt.% NaCl concentration through direct contact membrane distillation. The fabricated membrane showed a wonderful desalination achievement with salt rejection of 99.92% and flux of 12 LMH. Furthermore, the fabricated membrane showed a fine stability for long-term membrane distillation process for pure and desalinating high saline waters. The authors reported that the superhydrophobic titania nanofibrous ceramic membrane modified by fluorinated holds can be used for practical water desalination applications because of its great performance (Fan et al. 2017). Catalytic decomposition of water pollutants is one of the most effective techniques due to cheap, simple, ecofriendly and energy-saving nature of these techniques. Metallic and metal oxides such as Ag, Pd, TiO2, CuO, ZnO and Bi2WO6 show catalytic or photocatalytic activity and used as catalyst in catalytic decomposition of microorganisms such as bacteria, viruses etc. and organic compounds such as dyes, nitro compounds, pesticides, herbicides, drug molecules and so on. Moreover, these metallic and metal oxides have antibacterial features and can inhibit the growth of bacteria like Gram-positive, Gram-negative bacteria etc. Hence they are often used in water treatment procedures. Besides antibacterial and catalytic properties, these materials also gives important properties to nanofiber membranes mentioned upper sections and they can provide a superior surface active sites for adsorption of contaminants such as organic compounds, heavy metal ions and microorganisms. As such, a range of report have already proved that the degradation of organic pollutants and acquisition of disinfected water can be effectively achieved by using catalytic or photocatalytic properties of Ag, Pd, TiO2, CuO, ZnO and Bi2WO6 nanoparticles dispersed in a slurry system. However, a separation problem still continues to regain these nanocatalysts from the treated water. This problem leads to high operation cost and process difficulty. This problem could be resolved by using catalytic/photocatalytic membranes, which make system design easier for water treatment process. Most important of all, the self-cleaning feature of these materials prevents contaminants from adhering to the surface of these materials. Due to this effective self-cleaning nature of these materials, membranes including these metallic and metal oxides gain antifouling property. Hereby significant problems that limit the applicability of membranes and such as rapid fouling, loss of flux ratio and increase in operating cost are minimized or eliminated by using membranes have metallic or metal oxide nanoparticles. In photocatalysis process, Thanks

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to the light sources that can radiate UV or VIS regions, electrons in nano sized photocatalyst such as TiO2, CuO, ZnO and Bi2WO6 are promoted into the conduction band which leaves holes in the valence band. Afterwards, holes and electrons diffuse to the surface of photocatalyst reacting with the hydroxyl groups and oxygens to produce hydroxyl radicals and superoxides, which used to destroy organic contaminants and microorganisms. In recent years, scientists have made great efforts to produce new generation photocatalytic membranes by combining the properties of photocatalysts and nanofibers. Among all the photocatalysts, TiO2 nanoparticles are widely used to fabricate photocatalytic membrane due to its unique photocatalytic property, extraordinary photostability, chemical and thermal stability, comparatively low cost and low toxicity. Different applications on photocatalytic membranes containing TiO2 nanoparticles in literature are seen. Zhang et al. fabricated a TiO2 nanofiber membrane by coating TiO2 nanofibers on a ceramic hollow fiber membrane support using a simple dip-coating technique. This technique opened a simple way to fabricate photocatalytic membranes for water treatment. The TiO2 nanofiber membrane with mesh-like nanostructures has a porosity of about 80% and a pure water flux of 1700 L m−2 h−1). They used the TiO2 nanofiber membrane for removal of humic acid. While approximately 29% of humic acid was removed by filtration alone, approximately 90% of humic acid was removed by TiO2 nanofiber membrane due to improved performance of filtration along with the simultaneous photocatalytic degradation of humic acid. Moreover, the TiO2 nanofibers supplied a great reduction of membrane fouling under UV light irradiation (Zhang et al. 2016). An et al. fabricated a highly photocatalytic water purification three-dimensional nanofiber membranes by modifying nylon-6 nanofiber membranes with TiO2 nanoparticles. They deposited nylon-6 nanofibers and TiO2 nanoparticles on a soda lime glass substrate. The photocatalytic degradation performance of the fabricated membrane was checked on degradation of methylene blue solution by using a relatively weak UV irradiation (0.6 mW cm−2). The results showed that 100% degradation of methylene blue solution was achieved within 90 min (An et al. 2014). All of these applications suggested that nanofiber membranes containing TiO2 would open new routes for water treatment applications in the future. Over the last decade, the work of producing multifunctional membranes, which contain many features, has become more important than the membranes serving for a single purpose. Choi et al. have a significant contribution on development of multifunctional membrane systems. They fabricated a palladium-zeolite nanofiber as an effective multifunctional recyclable catalyst membrane for adsorption and catalytic removal of ammonium nitrogen (NH3-N) in waters. In this study, polyacrylontrile nanofiber was decorated by palladium and zeolite nanoparticles by using electrospinning technique. The characterization experiments demonstrated that zeolite and palladium nanoparticles were uniformly distributed and deposited on the nanofibers. NH3-N recovery yield increased from 23% to 92% when nanofiber was modified with palladium coated zeolite. The most important application of this membrane system is that NH3-N was adsorbed on the zeolites placed on the surface of fibers and palladium catalysts were capable of selective oxidation of NH3-N to N2 gas (Choi et al. 2016). The cycling of NH3-N adsorption-oxidation, flexibility, high flow

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rate and hydrophilicity of the nanofiber membrane, provides it a strong area of use in water treatment process (Choi et al. 2016). Chen et  al. produced a multifunctional polyacrylonitrile (PAN)-ZnO/Ag composite electrospun nanofiber membranes by using an electrospinning technique, hydrothermal ZnO synthesis, and Ag reduction. The performance of different type of nanofiber membranes including pineal-type, flower-type, and sea-urchin-type ZnO morphologies were checked as water purification filters and antibacterial and UV-shielding clothes. When compared with pure polyacrylontrile electrospinning nanofiber membranes, These PAN-ZnO/Ag composite electrospinning nanofiber membranes has better photocatalytic performance because the PAN-ZnO/Ag membranes contained ZnO and Ag. Moreover, the photocatalytic performance of polyacrylonitrile (PAN)-ZnO/Ag composite electrospun nanofiber membranes was checked degradation of methylene blue as dye pollution under UV light source. The results showed that sea-urchin type ZnO morphology has the best photocatalytic activity due to its a higher surface-to-volume ratio (Chen et al. 2015). They were achieved the degradation about 90% of the methylene blue in a short time (30 min.) by using polyacrylonitrile (PAN)-sea-urchin type ZnO/Ag composite electrospun nanofiber membranes (Chen et al. 2015). Lei et al. produced Ag/AgCl coated polyacrylonitrile nanofiber membranes has long-term stability, and flexibility by a facile and effective electrospinning technique and used photodegradation of methyl orange (MO) in water under visible-­ light (Lei et al. 2011). Membrane fouling problem leads to decreasing water permeability. Consequently, the operating cost of membrane processes are increased due to high energy consumption and the frequent need for cleaning and maintenance. Membrane fouling can be mainly classified in three types consist of biofouling, organic fouling and inorganic fouling. Inorganic and organic foulings are caused by the collection of inorganic and organic foulants such as salts, metal compounds, surfactants and proteins on the membrane surface. The deposition of microorganism communities on the membrane surface lead to growth and proliferation of the microorganism and moreover formation of biopolymer matrix or complex structure called as biofouling. Biofouling is a difficult problem to solve than other fouling problems in water treatment process since the secondary impurities create metabolic residues of the bacteria that have fixed and grown on the membrane surface. Further, inorganic and organic fouling problems can be solved by chlorine treatment or backwashing, while biofouling problem cannot be solved with these techniques. The antibacterial properties of membranes can be usually achieved in three different ways as follows biocide leaching (or release killing), contact killing and adhesion resistance. In the first way (release killing) biocide chemicals deposited into the membrane surface release cytotoxic complex and lead to killing bacteria in the feed solution. In this way, the deposition of bacteria on the membrane surface is decreased. Silver (Ag) nanoparticles are the most used biocide in the leaching approach. In the contact killing application as second way, the membrane surface is decorated by antibacterial materials like antimicrobial peptides and chemicals with quaternary ammonium groups. In the adhesion resistance application as third way,

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groups with the similar electrostatic charge polarity as bacteria improves the anti-­ adhesion features of the membrane surface via electrostatic pushing between the membrane surface and the bacteria. Zwitter ionic monomers have anionic and cationic groups on their chemical structures, which lead to electrically neutral structure and high hydrophilicity. Hence the modification of membrane surface with zwitter ionic monomers is a effective way to enhance adhesion resistance. In comparison to many metal and metal oxide antibacterial nanoparticles such as TiO2, ZnO, and Ag quote a few. Silver nanoparticles (Ag Nps) have more effect to control the growth of broad spectrum of microorganisms (bacteria, fungi, and viruses) which is proved by different reports. Hence, the modification of nanofibers with silver nanoparticles can not only significantly offer the membranes with antibacterial features but also improve the adsorption capacity. Further, the antibacterial feature can also play an important role to eliminate the bio-fouling problems caused by biota when the membrane is used for a long time. Zhao et al. fabricated antimicrobial three dimensional (3D) woven fabric filters by wrapping the weft yarn with electrospun nanofibers containing 2 wt% silver nanoparticles (Ag NPs). It was reported that the growth of bacterial colonies were suppressed with the fabrics and the yarns with Ag NPs nanofibers and Ag ions. The three dimensional (3D) woven fabric filters was used for treatment of activated sludge collected from a local municipal waste water treatment plant. 3D fabrics with the identical structure including Ag ion-commercial antimicrobial yarns and control yarns are also produced to compare filtration performance. A long term filtration experiments were applied the as-prepared membrane and control membrane. The experiments indicated that the as-prepared membrane including Ag NPs had 40–50% higher fluxes and quite larger flux recovery proportions than control filter. The other analyses showed that the fabric filter with Ag NPs nanofibers with lower antimicrobial agent than commercial antimicrobial filter had the lowest bacterial cell, polysaccharides, and protein clusters on surface and inside the first two layers of the fabric filters, which lead to antifouling on membrane (Zhao et al. 2017a, b). Kumar and Gopinath (2016) fabricated the silver nanoparticles incorporated functionalized MWCNTs grafted surface modified polyacrylontrile nanofibrous membrane (APAN–Ag/PEGylated MWCNT–COOH nanofibrous membrane) for the removal of toxic heavy metals and bacteria present in water as dual applications. The aminated polyacrylontrile (APAN) nanofibers as intermediate material in the intermediate of the membrane production shows the high performance for removal of the heavy metals while, the APAN–Ag/PEGylated MWCNT–COOH nanofibrous membrane as last production was found to have remarkable antibacterial features as well as filtration capability (Kumar and Gopinath 2016). Yuan et  al. fabricated a poly(vinyl alcohol)/silver (Ag–PVA) nanofiber membrane by sol–gel and electrospinning methods and used for removal of mercury pollution and antibacterial applications for water treatment. The as-prepared membrane had high adsorption capacity with wonderful resistance for wide pH value range in liquid solution. The antibacterial performance of the as-prepared membrane was tested against Escherichia coli and Staphylococcus aureus bacteria and it was found that the poly(vinyl alcohol)/ silver (Ag–PVA) nanofiber membrane showed high antibacterial property (Yuan et  al. 2017). Kim et  al. produced an antifouling bi-layered electrospun fibrous

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membrane consists of polyurethane nanofibers and silver nanoparticles. The membrane demonstrated that a thin layer of electrospun nanofibers enhanced the affectivity of filtration without important increase in pressure drop. Modification of polyurethane nanofibers with Ag NPs offered the antibacterial and antifouling properties to the membrane. The authors checked the filter efficiency and pressure drop rate by using oil aerosol flow and pressure measurements and antibacterial efficiency of nanofibers by using zone inhibition test on Staphylococcus aureus as Gram-positive bacteria and Escherichia coli as the Gram-negative bacteria (Kim et al. 2017).

6.3.1  Patents and Commercial Applications for Nanofiber-Based Membranes With the increasing importance of studies on the development of nanofiber based membranes, which offer users different advantages of use for water treatment process mentioned in the sections above, the patent and commercialization efforts in this area for industrial purposes on a large scale have gained momentum rapidly. The inventions provide novel, industrially easy to produce, industrially-scalable, industrially-viable, cost-efficient and high reactive of the nanofiber based membranes. Moreover, the important inventions on the nanofiber based membranes lead to user-friendly and deployable technology designs and reactor configurations. Some of the nanofiber based membranes patented and commercialized by different research groups, companies and institutions are summarized below. In a study patented by scientists from different institutes came together in Turkey, a tubular nanofiber-polyamide FO membrane has low reverse salt flux, low tendency of fouling, high water flux and large membrane in packaging volume was developed for water filtration. They used electrospinning production procedure to obtain fibers with a diameter of 300–400 nm. They achieved the 18 LMH of water flux and 99.4 of salt adhesion specified under the operating conditions in commercial membrane guide. According to the invention the tubular nanofiber forward osmosis membrane is industrially easy to produce and it becomes easy to use and cost-efficient by providing a module into which the membrane will be positioned (Koyuncu et al. 2018). Bin et al. fabricated and patented a bacterial cellulose nanofiber composite filter membrane which can be used for high-efficiency high-­ throughput water filtration. They completely covered the surface of the silica electrospun filter membrane with continuous two-dimensional network structure formed by bacterial cellulose nanofibers. The invention simultaneously has a continuous two-dimensional network structure completely covered on the surface and a high porosity, and can achieve high-efficiency filtration of impurities in the water under highthroughput conditions. The average pore diameter of the composite filter membrane is 0.2μm, the porosity is 80%, the filtration efficiency of impurities with a particle diameter of 0.3μm is 99.9%, and the pure water flux is 3500 L/m2h (Bin

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et al. 2017). Cwiertny et al. fabricated the polyacrylonitrile/Fe2O3@Fe2O3 electrospun nanofiber filters for removal of metal ions. They combined the electrospinning and hydrothermal coating synthesis procedure to fabricate the ­polyacrylonitrile/ Fe2O3@Fe2O3 electrospun nanofiber filters. Electrospun nanofibers generally are too weak or too brittle to be of practical use. However, in this study, the reactivity and strength of the electrospun nanofiber was improved. The invention solved problems typically encountered with electrospun nanofiber devices. This important development leads to composites nanofibers and electrospun filters that can be more easily handled and manipulated. The robust platform is user-friendly and deployable across a range of technology designs and reactor configurations. They designed a portable device that may be capable, being carried and moved. The new designed device may be carried by an adult or child with little or no effort (Cwiertny et al. 2017). Wu et al. (2011) were fabricated a glycosylated nanofiber membrane with boron selectivity and used its for removal of boron pollutants in wastewater and seawater with low operating pressure, high flux and high efficiency. The most important advantages of the glycosylated nanofiber membrane (glycosyl modified chitosan/polyvinyl alcohol nanofiber composite membrane) are that can be regenerated by simple acid and alkali treatment, can be repeatedly used, and the recovery rate is high when regeneration. The fabricated glycosyl modified chitosan/polyvinyl alcohol nanofiber composite membrane has high surface area, high porosity, stability and durability, which lead to effective treatment yields. Moreover, the fabricated nanofiber membrane has potential industrial application prospect (Wu et al. 2011). In recent years, active nano-carbon fibers have received more attention due to their high specific surface area, controllable micro mesoporous structure and good physical properties for water treatment applications. But the recycle problem of the carbon nanofiber is still going on. To solve this recycle problem, Ding et al. reported a different invention on the synthesis of magnetic benzoxazinyl carbon nanofiber material for water treatment, solvent recovery and gasoline trapping applications. They used the electrostatic spinning and solidification treatment procedures to obtain magnetic benzoxazinyl carbon nanofiber material. The magnetic carbon fiber material prepared meets the current social life needs and has a good practical application value (Ding et al. 2012). A urban surface source pollution water treatment system mainly consists of 4 parts follow as; a pool (1), the primary filtration system (2), the secondary filtration system (3) and the reservoir (4) communicate with each other. This water treatment system requires an external power source that consumes a lot of energy to operate. In order to solve this problem, Wei et al. produced a TiO2 nanofiber membrane, which has the characteristics of high efficiency, eliminated fouling problems, large membrane area, low price, stable performance for acidic and basic mediums. The fabricated TiO2 nanofiber membranes can effectively filter and adsorb small pollutants in waste water that can not be processed by a general sewage treatment system. And can effectively degrade these pollutants under UV light conditions. Moreover, TiO2 nanofiber membranes are flexible, capable of producing various types of commercial membrane modules (Wei et al. 2013). In another membrane application, a PVA-co-PE nanofiber membrane has a large surface area and a large amount of functional groups per unit area was fabricated and used for

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heavy metal adsorption in water treatment by researcher from Wuhan Textile University and Kunshan Wise Channel Hyper Technology Co Ltd. The invention combined a polyolefin copolymer as a matrix material, and a chemically modified nanofiber membrane via surface chemical modification and solid phase synthesis of active molecules (Dong et al. 2013). A research group from National Dong Hwa University produced a hydrophobic spinning nanofiber porous membrane for membrane distillation process. To obtain best membrane system, they checked a range of hydrophobic functional polymer material such as cellulose acetate, polydimethylsiloxane, polystyrene, polyetherimide, polyvinylidene fluoride, polyvinyl chloride, polysilsesquioxane, polyhydroxybutyrate, cage polymethyl methacrylate, polycarbonate, polyvinylidene fluoride/silica nanoparticle composites and fluorinated polyurethane. The fabricated nanofibers have an average diameter of 200–1000 nm, a porosity of 60–90%, a water contact angle of 125°–155°, and a thickness of 30–300 μm. The nanofiber porous membrane has an average pore size of 0.5–1.5 μm, a pore size distribution of 0.2–3.0 μm, and a gas permeability of 500–1500 L/m2.s (0.2%). Bar), the water osmotic pressure is 0.2 bar to 1.5 bar, and the water contact angle is 125°–155°. They claimed that the production method of the membrane is simple and easy to implement, and is easier to realize the operation of large-scale production. The highly hydrophobic nanofiber porous membrane provides significantly improvements on the water flux and membrane wettability defects of conventional membrane distillation membranes. Because of these improvements, membrane distillation technology can compete with reverse osmosis technology in seawater desalination applications (Xuefen et al. 2013). Yuming et al. used the electrospinning technique to produce iron-manganese nanooxid modified polyacrylonitrile nanofiber membrane. The produced membrane, which has large specific surface area, high porosity and strong toughness was used to remove Cd(II) ions from waste waters. By using the iron-manganese nanooxid modified polyacrylonitrile nanofiber membrane; fast adsorption kinetics, high adsorption capacity and easy separation was ensured for Cd(II) ions (Yuming et al. 2014a, b). In another application, iron/ chitosan/polyoxyethylene composite nanofiber membrane was prepared by a high-­ pressure electrospinning technique and used for removal of arsenic from wastewater and drinking water. The fabricated iron/chitosan/polyoxyethylene composite nanofiber membrane provides simple operation capability, strong acid and alkali resistance, high film flexibility, and good reproducibility (Yuming et al. 2014a, b). (Huali et al. 2017) were fabricated a graphene oxide monolayer modified polyacrylonitrile nanofiber membrane with a nontoxic and non-polluting process and patented this material for broad applications such as wastewater treatment, seawater desalination, medical dialysis and so on. The fabricated graphene oxide monolayer modified polyacrylonitrile nanofiber membrane has good practical and potential value for large-scale water treatment process (Huali et al. 2017). The airbrush technology is a precision device for painting applications. Its use and application areas are increasing day by day in parallel with developing technology. Compared with the traditional liquid-jet spinning pen, the liquid-jet spinning offers the benefits of high spinning efficiency, low energy consumption, easy control and flexible operation (Xueqiong et  al. 2016). Xueqiqng et  al. provided a

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invention, which related with a procedure for preparing oil-water separating nanofiber membranes by using airbrush instrument. In this airbrush technique, a high-­ molecular polymer solution is rapidly sprayed out of a nozzle under a high-pressure air flow, and the dried high-molecular fiber filaments are collected by a receiver (Xueqiong et al. 2016). Bin et al. reported a new invention about synthesis flexible titanium oxide nanofiber membrane as multifunctional material such as water treatment, hydrogen production, air purification, lithium ion batteries fields. The average diameter of single fibers of the flexible titanium oxide nanofiber membrane is 10–500 nm and the relative standard deviation is 1–5%; the flexible titanium oxide nanofiber membrane has a softness of 10–100  mN and has good flexibility. The most important advantage of the production of the flexible titanium oxide nanofiber membrane is that not require addition of a polymer or aging (Bin et al. 2014). Recently, nanofibers were explored for water treatment applications by various companies. Kevlar fiber is a high-performance para-aramid, which is known as poly(p-phenylene terephthalate) or Kevlar-1414. It has been used in industrial scale since 1970s. Poly(p-phenylene terephthalate) fiber is a strong molecule and has Inter-hydrogen bonds offer excellent performance such as high strength, Kevlar fiber polarity, acid and alkali corrosion resistance, high modulus and high temperature. In view of these excellent performance features of Kevlar fiber, it has gained extensive interest to prepare membranes with high strength, high water flux, and good salt rejection features (Jiwen et al. 2015). Cas Guangzhou Chemistry Co Ltd. Company fabricated a Kevlar nanofiber porous membrane for forward osmosis applications. The company resercher claimed that the production method provides important advantages such as easy realization of industrialized production, simple, cheap and quick operation and rapid film production process (Jiwen et al. 2015). Yinling Technology Wuxi Co. Ltd. company reported a new invention to prepare a polyamide reverse osmosis membrane by replacing the polysulfone scratch layer intermediate layer in a conventional polyamide composite reverse osmosis membrane with a hydrophilic coating-nanofiber membrane composite membrane. They used a electrospinning production procedure. Compared with traditional membranes, the most important advantage of the fabricated membranes is that they need low operating pressures and low energy consumptions. Moreover, they designed this electrospun nanofiber based composite membrane in order to meet the development and application necessities and improve the membrane performance such as anti-pollution performance, chlorine resistance, low pressure and low energy consumption (Congju 2015a, b). In other composite nanofiber membrane application carried out Yinling Technology Wuxi Co. Ltd. Company, magnesium-based composite nanofiber was fabricated by using a electrospinning method. Electrospun nanofiber membranes have been gradually used for the removal of heavy metal ions such as chitosan nanofiber membranes. Since most electrospun nanofiber membranes do not have the ability to remove heavy metal ions, The researchers from Yinling Technology Wuxi Co. Ltd. company modified nanofiber membranes to adsorb and remove Cr(VI) ions as heavy metal. The fabricated magnesium-based composite nanofiber mebrane with high specific surface area and high adsorption capacity provides easy removal and recycling performance advantages to users

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(Congju 2015a, b). A company known as Elmarco s.r.o provides the customer the industrial scale nanofiber based liquid filtration products across multiple industries. They used Nanospider™ electrospinning instrument to fabricate nanofibers in membranes (Elmarco s.r.o). Donaldson Company Inc. from USA fabricated polytetrafluoroethylene based membranes called as “Donaldson membranes”for filtration applications (Donaldson Company Inc.). A technology company from USA known as “E-spin Technologies Inc.” is produced highly chemical resistant nanofibers arranged in a thin nonwoven structure forms for water filtration process (E-spin Technologies Inc.). A multifunctional membrane system known as “Ahlstrom-­ Munksjö Hollytex®” is fabricated by Ahlstrom Corporation company and this membrane system is used as ultrafiltration membrane support, microporous membrane support, reverse osmosis membrane support and pleat support for membrane cartridge filters (Ahlstrom Corporation). A company known as “Toray” from Japan is produced polyacrylontrile-based carbon fibers for water treatment, aerospace and many other purposes. This company have different membrane systems called as “ROMEMBRA™, TORAYFIL™ and MEMBRAY™”, which are used for desalination of seawater and brackish water, treatment and recycling of sewage and industrial wastewater, wastewater reclamation from treated effluent, recovery of valuable components in different industrial areas (Toray Industries Inc.). Japan Vilene Company Ltd. fabricated different type of fiber based liquid filter systems (Japan Vilene Company Ltd.). Nanoval GmbH & Co. KG company from Germany produced polypropylen (PP) and polyethylen (PE) based nanofibers for water filtration process (Nanoval GmbH & Co. KG). Hills Inc. company from USA produced many type of nanofibers for different filtration applications (Hills Inc.). Esfil Tehno company from Republic of Estonia produced highly efficient polymeric and non-woven polymer filtering materials made of micro and nano fibers. This company patented the filtering materials and technologies in national and European patent boards (Esfil Tehno AS). “Technorbital Advanced Materials Pvt Ltd” is also important industry who is already producing nanofibers for water purification and treatment process (Technorbital Advanced Materials Pvt Ltd).

6.4  Conclusion Due to strategic importance of clean water for people, there is an immediate request for development of novel, cheap and environmentally sustainable water treatment process that can provide a safe water supply. Membrane technology offers effective and sustainable applications for water treatment process. The use of membranes is increasing day by day with the elimination of undesirable properties in the membranes and the attainment of the desired properties for the application purposes in water treatment process. However, time is still needed for the market commercialization of the membranes produced at the end of laboratory investigations. For future, it is believed that the emergency of new nanomaterials and nanotechnological applications will lead to cause of birth new commercial membranes with

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improved features and low operating costs for water treatment process and help solve the living global water crisis. Hence, a broader discussion of the most promising applications to fabricate new and innovative membranes with additional properties (high chemical and thermal stability, high surface area, high mechanical strength, high flow rate, antibiotic resistance, fouling resistance, catalytical reactivity and flexibility) for water treatment process by using nanofiber materials is provided.

References Abbey FM (2013) Assessing existing water demand and supply patterns and reuse options as additional sources of water in the Greater Accra Metropolitan Area (GAMA). Doctoral dissertation, University of Ghana. Adams C, Wang Y, Loftin K, Meyer M (2002) Removal of antibiotics from surface and distilled water in conventional water treatment processes. J Environ Eng 128(3):253–260. https://doi. org/10.1061/(ASCE)0733-­9372(2002)128:3(253) Agyemang FO, Li F, Momade FW, Kim H (2016) Effect of poly (ethylene oxide) and water on electrospun poly (vinylidene fluoride) nanofibers with enhanced mechanical properties as pre-filter for oil-in-water filtration. Mater Chem Phys 182:208–218. https://doi.org/10.1016/j. matchemphys.2016.07.025 Ahmad AL, Ismail S, Bhatia S (2003) Water recycling from palm oil mill effluent (POME) using membrane technology. Desalination 157(1-3):87–95. https://doi.org/10.1016/ S0011-­9164(03)00387-­4 Ahmadi A, Qanati O, Dorraji MS, Rasoulifard MH, Vatanpour V (2017) Investigation of antifouling performance a novel nanofibrous S-PVDF/PVDF and S-PVDF/PVDF/GO membranes against negatively charged oily foulants. J Membr Sci 536:86–97. https://doi.org/10.1016/j. memsci.2017.04.056 Ali I, Gupta VK (2006) Advances in water treatment by adsorption technology. Nat Protoc 1(6):2661–2667. https://doi.org/10.1038/nprot.2006.370 Ali I, Asim M, Khan TA (2012) Low cost adsorbents for the removal of organic pollutants from wastewater. J Environ Manag 113:170–183. https://doi.org/10.1016/j.jenvman.2012.08.028 Aliabadi M, Irani M, Ismaeili J, Piri H, Parnian MJ (2013) Electrospun nanofiber membrane of PEO/Chitosan for the adsorption of nickel, cadmium, lead and copper ions from aqueous solution. Chem Eng J 220:237–243. https://doi.org/10.1016/j.cej.2013.01.021 Alkhudhiri A, Darwish N, Hilal N (2012) Membrane distillation: a comprehensive review. Desalination 287:2–18. https://doi.org/10.1016/j.desal.2011.08.027 Alklaibi AM, Lior N (2005) Membrane-distillation desalination: status and potential. Desalination 171(2):111–131. https://doi.org/10.1016/j.desal.2004.03.024 Al-Obaidani S, Curcio E, Macedonio F, Di Profio G, Al-Hinai H, Drioli E (2008) Potential of membrane distillation in seawater desalination: thermal efficiency, sensitivity study and cost estimation. J Membr Sci 323(1):85–98. https://doi.org/10.1016/j.memsci.2008.06.006 An S, Lee MW, Joshi BN, Jo A, Jung J, Yoon SS (2014) Water purification and toxicity control of chlorophenols by 3D nanofiber membranes decorated with photocatalytic titania nanoparticles. Ceram Int 40(2):3305–3313. https://doi.org/10.1016/j.ceramint.2013.09.104 Arain M. B, Ali I, Yilmaz E, Soylak M (2018) Nanomaterial’s based chromium speciation in environmental samples: a review. TrAC-Trend Anal Chem 103:44–55. https://doi.org/10.1016/j. trac.2018.03.014 Aslan T, Arslan S, Eyvaz M, Güçlü S, Yüksel E, Koyuncu İ (2016) A novel nanofiber microfiltration membrane: Fabrication and characterization of tubular electrospun nanofiber (TuEN) membrane. J Membr Sci 520:616–629. https://doi.org/10.1016/j.memsci.2016.08.014

6  Nanotechnological Developments in Nanofiber-Based Membranes Used for Water…

247

Aydogdu A, Sumnu G, Sahin S (2018) A novel electrospun hydroxypropyl methylcellulose/polyethylene oxide blend nanofibers: Morphology and physicochemical properties. Carbohydr Polym 181:234–246. https://doi.org/10.1016/j.carbpol.2017.10.071 Bae J, Baek I, Choi H (2016) Mechanically enhanced PES electrospun nanofiber membranes (ENMs) for microfiltration: The effects of ENM properties on membrane performance. Water Res 105:406–412. https://doi.org/10.1016/j.watres.2016.09.020 Baghban N, Yilmaz E, Soylak M (2017) Nanodiamond/MoS2 nanorod composite as a novel sorbent for fast and effective vortex-assisted micro solid phase extraction of lead (II) and copper (II) for their flame atomic absorption spectrometric detection. J Mol Liq 234:260–267. https:// doi.org/10.1016/j.molliq.2017.03.079 Bahmani P, Maleki A, Daraei H, Khamforoush M, Rezaee R, Gharibi F et  al (2017) High-flux ultrafiltration membrane based on electrospun polyacrylonitrile nanofibrous scaffolds for arsenate removal from aqueous solutions. J Colloid Interface Sci 506:564–571. https://doi. org/10.1016/j.jcis.2017.07.086 Baker RW (2000) Membrane technology. Wiley, Hoboken Baron J (1997) Repair of wastewater microorganisms after ultraviolet disinfection under seminatural conditions. Water Environ Res 69(5):992–998 Bin D, Jun S, Xue M, Weidong H, Jianyong Y (2014) Flexible titanium oxide nanofiber membrane and preparation method thereof. Patent application number: CN20141369281 Bin D, Shichao Z, Ning T, Lifang L, Jianyong Y (2017) Bacterial cellulose nanofiber composite filtration membrane and preparation method thereof. Patent application number: CN107335346 (A) Bond EB, Chhabra R, Isele OEA, Xu H (2009) U.S.  Patent No. 7,576,019. U.S.  Patent and Trademark Office, Washington, DC Bouwer H (2002) Integrated water management for the 21st century: problems and solutions. J Irrig Drain Eng 128(4):193–202. https://doi.org/10.1061/(ASCE)0733-­9437(2002)128:4(193) Brame J, Li Q, Alvarez PJ (2011) Nanotechnology-enabled water treatment and reuse: emerging opportunities and challenges for developing countries. Trends Food Sci Technol 22(11):618–624. https://doi.org/10.1016/j.tifs.2011.01.004 Brix H (1994) Use of constructed wetlands in water pollution control: historical development, present status, and future perspectives. Water Sci Technol 30(8):209–223. https://doi.org/10.3390/ w9060397 Bui NN, McCutcheon JR (2014) Nanofiber supported thin-film composite membrane for pressure-­ retarded osmosis. Environ Sci Technol 48(7):4129–4136. https://doi.org/10.1021/es4037012 Cabassud C, Wirth D (2003) Membrane distillation for water desalination: how to chose an appropriate membrane? Desalination 157(1):307–314. https://doi.org/10.1016/S0011-­9164(03)00410-­7 Cao J, Cheng Z, Kang L, Chu M, Wu D, Li M et al (2017) Novel stellate poly (vinylidene fluoride)/ polyethersulfone microsphere-nanofiber electrospun membrane with special wettability for oil/ water separation. Mater Lett 207:190–194. https://doi.org/10.1016/j.matlet.2017.07.044 Carpenter AW, de Lannoy CF, Wiesner MR (2015) Cellulose nanomaterials in water treatment technologies. Environ Sci Technol 49(9):5277–5287. https://doi.org/10.1021/es506351r Cath TY, Childress AE, Elimelech M (2006) Forward osmosis: principles, applications, and recent developments. J Membr Sci 281(1):70–87. https://doi.org/10.1016/j.memsci.2006.05.048 Chen YY, Kuo CC, Chen BY, Chiu PC, Tsai PC (2015) Multifunctional polyacrylonitrile ZnO/ Ag electrospun nanofiber membranes with various ZnO morphologies for photocatalytic, UV-shielding, and antibacterial applications. J Polym Sci B Polym Phys 53(4):262–269. https://doi.org/10.1002/polb.23621 Chen H, Lin J, Zhang N, Chen L, Zhong S, Wang Y et al (2017) Preparation of MgAl-EDTA-LDH based electrospun nanofiber membrane and its adsorption properties of copper (II) from wastewater. J Hazard Mater. https://doi.org/10.1016/j.jhazmat.2017.11.002 Chen Z, Luo J, Hang X, Wan Y (2018) Physicochemical characterization of tight nanofiltration membranes for dairy wastewater treatment. J Membr Sci 547:51–63. https://doi.org/10.1016/j. memsci.2017.10.037

248

E. Yilmaz and M. Soylak

Cheng B, Li Z, Li Q, Ju J, Kang W, Naebe M (2017) Development of smart poly (vinylidene fluoride)-graft-poly (acrylic acid) tree-like nanofiber membrane for pH-responsive oil/water separation. J Membr Sci 534:1–8. https://doi.org/10.1016/j.memsci.2017.03.053 Chi XY, Zhang PY, Guo XJ, Xu ZL (2018) A novel TFC forward osmosis (FO) membrane supported by polyimide (PI) microporous nanofiber membrane. Appl Surf Sci 427:1–9. https://doi. org/10.1016/j.apsusc.2017.07.259 Chitpong N, Husson SM (2017a) High-capacity, nanofiber-based ion-exchange membranes for the selective recovery of heavy metals from impaired waters. Sep Purif Technol 179:94–103. https://doi.org/10.1016/j.seppur.2017.02.009 Chitpong N, Husson SM (2017b) Polyacid functionalized cellulose nanofiber membranes for removal of heavy metals from impaired waters. J Membr Sci 523:418–429. https://doi. org/10.1016/j.memsci.2016.10.020 Choi J, Chan S, Yip G, Joo H, Yang H, Ko FK (2016) Palladium-Zeolite nanofiber as an effective recyclable catalyst membrane for water treatment. Water Res 101:46–54. https://doi. org/10.1016/j.watres.2016.05.051 Chong MN, Jin B, Chow CW, Saint C (2010) Recent developments in photocatalytic water treatment technology: a review. Water Res 44(10):2997–3027. https://doi.org/10.1016/j. watres.2010.02.039 Chowdhury MR, Huang L, McCutcheon JR (2017) Thin film composite membranes for forward osmosis supported by commercial nanofiber nonwovens. Ind Eng Chem Res 56(4):1057–1063. https://doi.org/10.1021/acs.iecr.6b04256 Chung TS, Zhang S, Wang KY, Su J, Ling MM (2012) Forward osmosis processes: yesterday, today and tomorrow. Desalination 287:78–81. https://doi.org/10.1016/j.desal.2010.12.019 Cloete TE (ed) (2010) Nanotechnology in water treatment applications. Horizon Scientific Press Congju L (2015a) Composite nanofiber membrane and making method thereof. Patent application number: CN2014188644. Congju L (2015b) Electrostatic spinning nanofiber membrane-based composite reverse osmosis membrane production method. Patent application number: CN2014188645. Costa AR, De Pinho MN (2006) Performance and cost estimation of nanofiltration for surface water treatment in drinking water production. Desalination 196(1-3):55–65. https://doi. org/10.1016/j.desal.2005.08.030 Cwiertny DM, Myung NV, Peter KT, Greenstein KE, Parkin GF (2017) Electrospun nanofiber composites for water treatment applications. International application number: PCT/ US2017/034663 Dabaghian Z, Rahimpour A (2015) Carboxylated carbon nanofibers as hydrophilic porous material to modification of cellulosic membranes for forward osmosis desalination. Chem Eng Res Des 104:647–657. https://doi.org/10.1016/j.cherd.2015.10.008 Dabaghian Z, Rahimpour A, Jahanshahi M (2016) Highly porous cellulosic nanocomposite membranes with enhanced performance for forward osmosis desalination. Desalination 381:117–125. https://doi.org/10.1016/j.desal.2015.12.006 Daniel MC, Astruc D (2004) Gold nanoparticles: assembly, supramolecular chemistry, quantum-­ size-­related properties, and applications toward biology, catalysis, and nanotechnology. Chem Rev 104(1):293–346. https://doi.org/10.1021/cr030698+ Daskalaki VM, Antoniadou M, Li Puma G, Kondarides DI, Lianos P (2010) Solar light-responsive Pt/CdS/TiO2 photocatalysts for hydrogen production and simultaneous degradation of inorganic or organic sacrificial agents in wastewater. Environ Sci Technol 44(19):7200–7205. https://doi.org/10.1021/es9038962 Dijkshoorn JP, Schutyser MAI, Wagterveld RM, Schroën CGPH, Boom RM (2017) A comparison of microfiltration and inertia-based microfluidics for large scale suspension separation. Sep Purif Technol 173:86–92. https://doi.org/10.1016/j.seppur.2016.09.018 Ding B, Ren T, Si Y, Yu J (2012) Method for preparing magnetic benzoxazinyl carbon nanofiber material. Patent application number: CN20121136273

6  Nanotechnological Developments in Nanofiber-Based Membranes Used for Water…

249

Dong W, Ying L, Zhihong W, Qinghua Z, Mufang L (2013) Nanofiber membrane with heavy metal absorption function and preparation method thereof. Patent application number: CN20121566477. Ellison CJ, Phatak A, Giles DW, Macosko CW, Bates FS (2007) Melt blown nanofibers: fiber diameter distributions and onset of fiber breakup. Polymer 48(11):3306–3316. https://doi. org/10.1016/j.polymer.2007.04.005 Fan Y, Chen S, Zhao H, Liu Y (2017) Distillation membrane constructed by TiO2 nanofiber followed by fluorination for excellent water desalination performance. Desalination 405:51–58. https://doi.org/10.1016/j.desal.2016.11.028 Favre-Réguillon A, Lebuzit G, Murat D, Foos J, Mansour C, Draye M (2008) Selective removal of dissolved uranium in drinking water by nanofiltration. Water Res 42(4):1160–1166. https://doi. org/10.1016/j.watres.2007.08.034 Feng X, Huang RY (1997) Liquid separation by membrane pervaporation: a review. Ind Eng Chem Res 36(4):1048–1066. https://doi.org/10.1021/ie960189g Feng C, Khulbe KC, Matsuura T, Gopal R, Kaur S, Ramakrishna S, Khayet M (2008) Production of drinking water from saline water by air-gap membrane distillation using polyvinylidene fluoride nanofiber membrane. J Membr Sci 311(1):1–6. https://doi.org/10.1016/j.memsci.2007.12.026 Feng C, Khulbe KC, Matsuura T, Tabe S, Ismail AF (2013) Preparation and characterization of electro-spun nanofiber membranes and their possible applications in water treatment. Sep Purif Technol 102:118–135. https://doi.org/10.1016/j.seppur.2012.09.037 Formo E, Yavuz MS, Lee EP, Lane L, Xia Y (2009) Functionalization of electrospun ceramic nanofibre membranes with noble-metal nanostructures for catalytic applications. J Mater Chem 19(23):3878–3882. https://doi.org/10.1039/B901509D Fu F, Wang Q (2011) Removal of heavy metal ions from wastewaters: a review. J Environ Manag 92(3):407–418. https://doi.org/10.1016/j.jenvman.2010.11.011 Gleick PH (2000) A look at twenty-first century water resources development. Water Int 25(1):127–138. https://doi.org/10.1080/02508060008686804 Gleick PH (2003) Global freshwater resources: soft-path solutions for the 21st century. Science 302(5650):1524–1528. https://doi.org/10.1126/science.1089967 Gray NF (2010) Water technology: an introduction for environmental scientists and engineers (No. Ed. 3). IWA Publishing Gray GT, McCutcheon JR, Elimelech M (2006) Internal concentration polarization in forward osmosis: role of membrane orientation. Desalination 197(1-3):1–8. https://doi.org/10.1016/j. desal.2006.02.003 Grether JM, De Melo J (2003) Globalization and dirty industries: do pollution havens matter? (No. w9776). National Bureau of Economic Research Gyürék LL, Finch GR (1998) Modeling water treatment chemical disinfection kinetics. J Environ Eng 124(9):783–793. https://doi.org/10.1061/(ASCE)0733-­9372(1998)124:9(783 Hammer MJ (1986) Water and wastewater technology Han C, Jing M, Shen X, Qiao G (2016) Electrospinning fabrication of mesoporous nano Fe2O3-­ TiO2@activated carbon fiber membrane for hybrid removal of phenol from waste water. Russ J Appl Chem 89(12):2008–2015. https://doi.org/10.1134/S1070427216120120 Hanioka S, Maruyama T, Sotani T, Teramoto M, Matsuyama H, Nakashima K et al (2008) CO2 separation facilitated by task-specific ionic liquids using a supported liquid membrane. J Membr Sci 314(1):1–4. https://doi.org/10.1016/j.memsci.2008.01.029 Hansen S, Bhatia R (2004) Water and poverty in a macro-economic context. Norwegian Ministry of the Environment. Hartgerink JD, Beniash E, Stupp SI (2001) Self-assembly and mineralization of peptide-­amphiphile nanofibers. Science 294(5547):1684–1688. https://doi.org/10.1126/science.1063187 Hedayatipour M, Jaafarzadeh N, Ahmadmoazzam M (2017) Removal optimization of heavy metals from effluent of sludge dewatering process in oil and gas well drilling by nanofiltration. J Environ Manag 203:151–156. https://doi.org/10.1016/j.jenvman.2017.07.070

250

E. Yilmaz and M. Soylak

Henze M, Harremoes P, la Cour Jansen J, Arvin E (2001) Wastewater treatment: biological and chemical processes. Springer Science & Business Media Herzberg M, Elimelech M (2007) Biofouling of reverse osmosis membranes: role of biofilm-­ enhanced osmotic pressure. J Membr Sci 295(1):11–20. https://doi.org/10.1016/j. memsci.2007.02.024 Hillie T, Hlophe M (2007) Nanotechnology and the challenge of clean water. Nat Nanotechnol 2(11):663–664. https://doi.org/10.1038/nnano.2007.350 Ho CC, Zydney AL (2000) A combined pore blockage and cake filtration model for protein fouling during microfiltration. J Colloid Interface Sci 232(2):389–399. https://doi.org/10.1006/ jcis.2000.7231 Homaeigohar S, Elbahri M (2014) Nanocomposite electrospun nanofiber membranes for environmental remediation. Materials 7(2):1017–1045. https://doi.org/10.3390/ma7021017 Homaeigohar SS, Buhr K, Ebert K (2010) Polyethersulfone electrospun nanofibrous composite membrane for liquid filtration. J Membr Sci 365(1):68–77. https://doi.org/10.1016/j. memsci.2010.08.041 Hoover LA, Schiffman JD, Elimelech M (2013) Nanofibers in thin-film composite membrane support layers: Enabling expanded application of forward and pressure retarded osmosis. Desalination 308:73–81. https://doi.org/10.1016/j.desal.2012.07.019 Hou H, Ge JJ, Zeng J, Li Q, Reneker DH, Greiner A, Cheng SZ (2005) Electrospun polyacrylonitrile nanofibers containing a high concentration of well-aligned multiwall carbon nanotubes. Chem Mater 17(5):967–973. https://doi.org/10.1021/cm0484955 Huali N, Huiqin Y, Deqiang C (2017) Method for preparing graphene oxide monolayer modified polyacrylonitrile nanofiber membrane. Patent application number: CN20171198655. Huang L, Manickam SS, McCutcheon JR (2013) Increasing strength of electrospun nanofiber membranes for water filtration using solvent vapor. J Membr Sci 436:213–220. https://doi. org/10.1016/j.memsci.2012.12.037 Hutchison JE (2008) Greener nanoscience: a proactive approach to advancing applications and reducing implications of nanotechnology. ACS NANO 2(3):395–402. https://doi.org/10.1021/ nn800131j Ignatious F, Sun L, Lee CP, Baldoni J (2010) Electrospun nanofibers in oral drug delivery. Pharm Res 27(4):576–588. https://doi.org/10.1007/s11095-­010-­0061-­6 Im JS, Kim MI, Lee YS (2008) Preparation of PAN-based electrospun nanofiber webs containing TiO2 for photocatalytic degradation. Mater Lett 62(21):3652–3655. https://doi.org/10.1016/j. matlet.2008.04.019 Islam MS, McCutcheon JR, Rahaman MS (2017) A high flux polyvinyl acetate-coated electrospun nylon 6/SiO2 composite microfiltration membrane for the separation of oil-in-water emulsion with improved antifouling performance. J Membr Sci 537:297–309. https://doi.org/10.1016/j. memsci.2017.05.019 Israr M, Hashmi MS, Ahmad N, Rahman G, Ahmad S, Ali S (2015) Devastating flood of 2010, effect on potabile water supply in Rural Swat. Am J Water Resour 3(4):118–123. https://doi. org/10.1371/4fdfb212d2432 Jacangelo JG, Trussell RR, Watson M (1997) Role of membrane technology in drinking water treatment in the United States. Desalination 113(2-3):119–127. https://doi.org/10.1016/ S0011-­9164(97)00120-­3 Jiang Y, Hou J, Xu J, Shan B (2017) Switchable oil/water separation with efficient and robust Janus  nanofiber membranes. Carbon 115:477–485. https://doi.org/10.1016/j. carbon.2017.01.053 Jin Y, Jia M (2014) Preparation and electrochemical capacitive performance of polyaniline nanofiber-­ graphene oxide hybrids by oil–water interfacial polymerization. Synth Met 189:47–52. https://doi.org/10.1016/j.synthmet.2013.12.016 Jiwen H, Tingting J, Tao J, Shengyu H, Fameng Y, Yuanyum T (2015) Kevlar nanofiber composite forward osmosis membrane, and preparation method and application thereof. Patent application number: CN20141830769

6  Nanotechnological Developments in Nanofiber-Based Membranes Used for Water…

251

Joshi P, Beck K (2018) Democracy and carbon dioxide emissions: assessing the interactions of political and economic freedom and the environmental Kuznets curve. Energy Res Social Sci 39:46–54. https://doi.org/10.1016/j.erss.2017.10.020 Khan S, Cao Q, Zheng YM, Huang YZ, Zhu YG (2008) Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China. Environ Pollut 152(3):686–692. https://doi.org/10.1016/j.envpol.2007.06.056 Khayet M (2011) Membranes and theoretical modeling of membrane distillation: a review. Adv Colloid Interf Sci 164(1):56–88. https://doi.org/10.1016/j.cis.2010.09.005 Kiani S, Mousavi SM, Shahtahmassebi N, Saljoughi E (2016) Preparation and characterization of polyphenylsulfone nanofibrous membranes for the potential use in liquid filtration. Desalin Water Treat 57(35):16250–16259. https://doi.org/10.1080/19443994.2015.1079258 Kim HJ, Han SW, Joshi MK, Kim CS (2017) Fabrication and characterization of silver nanoparticle-­ incorporated bilayer electrospun–melt-blown micro/nanofibrous membrane. Int J Polym Mater Polym Biomater 66(10):514–520. https://doi.org/10.1080/00914037.2016.1255615 Koyuncu I, Guclu S, Eyvaz M, Aslan T, Arslan S, Yuksekdag A, Yuksel E (2018) Manufacturing of a nanofiber forward osmosis membrane with tubular shape. Patent application number: WO2016TR50411. Kristensen LJ, Taylor MP, Flegal AR (2017) An odyssey of environmental pollution: the rise, fall and remobilisation of industrial lead in Australia. Appl Geochem. https://doi.org/10.1016/j. apgeochem.2017.02.007 Kumar SR, Gopinath P (2016) Dual applications of silver nanoparticles incorporated functionalized MWCNTs grafted surface modified PAN nanofibrous membrane for water purification. RSC Adv 6(110):109241–109252. https://doi.org/10.1039/c6ra22735j Lacalle RG, Gómez-Sagasti MT, Artetxe U, Garbisu C, Becerril JM (2018) Brassica napus has a key role in the recovery of the health of soils contaminated with metals and diesel by rhizoremediation. Sci Total Environ 618:347–356. https://doi.org/10.1016/j.scitotenv.2017.10.334 Lawson KW, Lloyd DR (1997) Membrane distillation. J Membr Sci 124(1):1–25 Lee EJ, An AK, He T, Woo YC, Shon HK (2016a) Electrospun nanofiber membranes incorporating fluorosilane-coated TiO2 nanocomposite for direct contact membrane distillation. J Membr Sci 520:145–154. https://doi.org/10.1016/j.memsci.2016.07.019 Lee J, Boo C, Ryu WH, Taylor AD, Elimelech M (2016b) Development of omniphobic desalination membranes using a charged electrospun nanofiber scaffold. ACS Appl Mater Interfaces 8(17):11154–11161. https://doi.org/10.1021/acsami.6b02419 Lefebvre O, Moletta R (2006) Treatment of organic pollution in industrial saline wastewater: a literature review. Water Res 40(20):3671–3682. https://doi.org/10.1016/j.watres.2006.08.027 Lei J, Wang W, Song M, Dong B, Li Z, Wang C, Li L (2011) Ag/AgCl coated polyacrylonitrile nanofiber membranes: synthesis and photocatalytic properties. React Funct Polym 71(11):1071–1076. https://doi.org/10.1016/j.reactfunctpolym.2011.08.002 Lhassani A, Rumeau M, Benjelloun D, Pontie M (2001) Selective demineralization of water by nanofiltration application to the defluorination of brackish water. Water Res 35(13):3260–3264. https://doi.org/10.1016/S0043-­1354(01)00020-­3 Li Z, Kang W, Zhao H, Hu M, Wei N, Qiu J, Cheng B (2016) A novel polyvinylidene fluoride tree-­ like nanofiber membrane for microfiltration. Nanomaterials 6(8):152. https://doi.org/10.3390/ nano6080152 Liang HW, Guan QF, Chen LF, Zhu Z, Zhang WJ, Yu SH (2012) Macroscopic-scale template synthesis of robust carbonaceous nanofiber hydrogels and aerogels and their applications. Angew Chem Int Ed 51(21):5101–5105. https://doi.org/10.1002/anie.201200710 Liao Y, Li XG, Hoek EM, Kaner RB (2013) Carbon nanotube/polyaniline nanofiber ultrafiltration membranes. J Mater Chem A 1(48):15390–15396. https://doi.org/10.1039/c3ta13902f Lim AL, Bai R (2003) Membrane fouling and cleaning in microfiltration of activated sludge wastewater. J Membr Sci 216(1):279–290. https://doi.org/10.1016/S0376-­7388(03)00083-­8 Liu R, Huang X, Chen L, Wen X, Qian Y (2005) Operational performance of a submerged membrane bioreactor for reclamation of bath wastewater. Process Biochem 40(1):125–130. https:// doi.org/10.1080/19443994.2012.677553

252

E. Yilmaz and M. Soylak

Liu L, Liu Z, Bai H, Sun DD (2012) Concurrent filtration and solar photocatalytic disinfection/degradation using high-performance Ag/TiO2 nanofiber membrane. Water Res 46(4):1101–1112. https://doi.org/10.1016/j.watres.2011.12.009 Liu Y, Ma H, Liu B, Hsiao BS, Chu B (2015) High-performance nanofibrous membrane for removal of Cr (VI) from contaminated water. J Plastic Film Sheeting 31(4):379–400 Liu Y, Ta W, Cherubini P, Liu R, Wang Y, Sun C (2018) Elements content in tree rings from Xi’an, China and environmental variations in the past 30 years. Sci Total Environ 619:120–126. https://doi.org/10.1016/j.scitotenv.2017.11.075 Lu X, Wang C (2014) Electrospun nanofiber-based photocatalysts. In: Electrospun nanofibers for energy and environmental applications. Springer, Berlin/Heidelberg, pp 371–401 Luo M, Hou X, Gu Y, Lau NC, Yim SHL (2018) Trans-boundary air pollution in a city under various atmospheric conditions. Sci Total Environ 618:132–141. https://doi.org/10.1016/j. scitotenv.2017.11 Lv Y, Du Y, Chen ZX, Qiu WZ, Xu ZK (2018) Nanocomposite membranes of polydopamine/ electropositive nanoparticles/polyethyleneimine for nanofiltration. J Membr Sci 545:99–106. https://doi.org/10.1016/j.memsci.2017.09.066 Ma Q, Cheng H, Yu Y, Huang Y, Lu Q, Han S et al (2017a) Preparation of superhydrophilic and underwater superoleophobic nanofiber-based meshes from waste glass for multifunctional oil/ water separation. Small 13(19). https://doi.org/10.1002/smll.201700391 Ma W, Samal SK, Liu Z, Xiong R, De Smedt SC, Bhushan B et al (2017b) Dual pH-and ammonia-­ vapor-­responsive electrospun nanofibrous membranes for oil-water separations. J Membr Sci 537:128–139. https://doi.org/10.1016/j.memsci.2017.04.063 Magara Y, Kunikane S, Itoh M (1998) Advanced membrane technology for application to water treatment. Water Sci Technol 37(10):91–99. https://doi.org/10.1016/S0273-­1223(98)00307-­2 Mahadik S (2017) Applications of Nanotechnology in Water and Waste Water Treatment. AADYA Natl J Manage Technol (NJMT) 7:187–191. https://doi.org/10.1016/j.watres.2012.09.058 Mahdavi H, Moslehi M (2016) A new thin film composite nanofiltration membrane based on PET nanofiber support and polyamide top layer: preparation and characterization. J Polym Res 23(12):257. https://doi.org/10.1007/s10965-­016-­1157-­4 Manohar DM, Krishnan KA, Anirudhan TS (2002) Removal of mercury (II) from aqueous solutions and chlor-alkali industry wastewater using 2-mercaptobenzimidazole-clay. Water Res 36(6):1609–1619. https://doi.org/10.1016/S0043-­1354(01)00362-­1 Martinez-Huitle CA, Ferro S (2006) Electrochemical oxidation of organic pollutants for the wastewater treatment: direct and indirect processes. Chem Soc Rev 35(12):1324–1340. https://doi. org/10.1039/b517632h Masindi V, Osman MS, Abu-Mahfouz AM (2017) Integrated treatment of acid mine drainage using BOF slag, lime/soda ash and reverse osmosis (RO): implication for the production of drinking water. Desalination 424:45–52. https://doi.org/10.1016/j.desal.2017.10.002 Maynard AD, Aitken RJ, Butz T, Colvin V, Donaldson K, Oberdörster G et al (2006) Safe handling of nanotechnology. Nature 444(7117):267–269. https://doi.org/10.1038/nnano.2016.270 Medina R, Gara PMD, Fernández-González AJ, Rosso JA, Del Panno MT (2018) Remediation of a soil chronically contaminated with hydrocarbons through persulfate oxidation and bioremediation. Sci Total Environ 618:518–530. https://doi.org/10.1016/j.scitotenv.2017.10.326 Mnyusiwalla A, Daar AS, Singer PA (2003) ‘Mind the gap’: science and ethics in nanotechnology. Nanotechnology 14(3):R9. https://doi.org/10.1088/0957-­4484/14/3/201 Mohamed IM, Yasin AS, Barakat NA, Song SA, Lee HE, Kim SS (2017) Electrocatalytic behavior of a nanocomposite of Ni/Pd supported by carbonized PVA nanofibers towards formic acid, ethanol and urea oxidation: A physicochemical and electro-analysis study. Appl Surf Sci. https://doi.org/10.1016/j.apsusc.2017.11.076 Mohanpuria P, Rana NK, Yadav SK (2008) Biosynthesis of nanoparticles: technological concepts and future applications. J Nanopart Res 10(3):507–517. https://doi.org/10.1007/ s11051-­007-­9275-­x Mondal S, Wickramasinghe SR (2008) Produced water treatment by nanofiltration and reverse osmosis membranes. J Membr Sci 322(1):162–170. https://doi.org/10.1016/j.memsci.2008.05.039

6  Nanotechnological Developments in Nanofiber-Based Membranes Used for Water…

253

Moradi G, Rajabi L, Dabirian F, Zinadini S (2018) Biofouling alleviation and flux enhancement of electrospun PAN microfiltration membranes by embedding of para-aminobenzoate alumoxane nanoparticles. J Appl Polym Sci. https://doi.org/10.1002/app.45738 Muller EB, Stouthamer AH, van Verseveld HWV, Eikelboom DH (1995) Aerobic domestic waste water treatment in a pilot plant with complete sludge retention by cross-flow filtration. Water Res 29(4):1179–1189 Nativ P, Lahav O, Gendel Y (2018) Separation of divalent and monovalent ions using flow-­ electrode capacitive deionization with nanofiltration membranes. Desalination 425:123–129. https://doi.org/10.1016/j.desal.2017.10.026 Neghlani PK, Rafizadeh M, Taromi FA (2011) Preparation of aminated-polyacrylonitrile nanofiber membranes for the adsorption of metal ions: Comparison with microfibers. J Hazard Mater 186(1):182–189. https://doi.org/10.1016/j.jhazmat.2010.10.121 Nicolaisen B (2003) Developments in membrane technology for water treatment. Desalination 153(1-3):355–360 Nie C, Zhan Y, Pan L, Li H, Sun Z (2011) Electrosorption of different cations and anions with membrane capacitive deionization based on carbon nanotube/nanofiber electrodes and ion-exchange membranes. Desalin Water Treat 30(1-3):266–271. https://doi.org/10.5004/dwt.2011.2089 Nie C, Yang Y, Peng Z, Cheng C, Ma L, Zhao C (2017) Aramid nanofiber as an emerging nanofibrous modifier to enhance ultrafiltration and biological performances of polymeric membranes. J Membr Sci 528:251–263. https://doi.org/10.1016/j.memsci.2016.12.070 Nunes SP, Peinemann KV (2001) Membrane technology. Wiley-vch O’Bannon C, Carr J, Seekell DA, D’Odorico P (2014) Globalization of agricultural pollution due to international trade. Hydrol Earth Syst Sci 18(2):503. https://doi.org/10.5194/hess-­18-­503-­2014 Obaid M, Ghouri ZK, Fadali OA, Khalil KA, Almajid AA, Barakat NA (2016) Amorphous SiO2 NP-incorporated poly (vinylidene fluoride) electrospun nanofiber membrane for high flux forward osmosis desalination. ACS Appl Mater Interfaces 8(7):4561–4574. https://doi. org/10.1021/acsami.5b09945 Obaid M, Mohamed HO, Yasin AS, Yassin MA, Fadali OA, Kim H, Barakat NA (2017) Under-oil superhydrophilic wetted PVDF electrospun modified membrane for continuous gravitational oil/water separation with outstanding flux. Water Res 123:524–535. https://doi.org/10.1016/j. watres.2017.06.079 Ochando-Pulido JM, Martinez-Ferez A (2018) Operation setup of a nanofiltration membrane unit for purification of two-phase olives and olive oil washing wastewaters. Sci Total Environ 612:758–766. https://doi.org/10.1016/j.scitotenv.2017.08.287 Okamoto M, Watanabe K, Izumi Z, Aya T, Kitagawa H (1977) U.S.  Patent No. 4,008,344. U.S. Patent and Trademark Office, Washington, DC Pan J, He Y, Wu L, Jiang C, Wu B, Mondal AN et al (2015) Anion exchange membranes from hot-pressed electrospun QPPO–SiO2 hybrid nanofibers for acid recovery. J Membr Sci 480:115–121. https://doi.org/10.1016/j.memsci.2015.01.040 Papageorgiou SK, Katsaros FK, Favvas EP, Romanos GE, Athanasekou CP, Beltsios KG et  al (2012) Alginate fibers as photocatalyst immobilizing agents applied in hybrid photocatalytic/ ultrafiltration water treatment processes. Water Res 46(6):1858–1872. https://doi.org/10.1016/j. watres.2012.01.005 Park B (2007) Current and future applications of nanotechnology. Issues Environ Sci Technol 24(1):1–18. https://doi.org/10.1039/1465-­1874 Park C, Engel ES, Crowe A, Gilbert TR, Rodriguez NM (2000) Use of carbon nanofibers in the removal of organic solvents from water. Langmuir 16(21):8050–8056. https://doi.org/10.1021/ la9916068 Park CH, Bae H, Kwak SJ, Jang MS, Lee JH, Lee J (2016) Interconnection of electrospun nanofibers via a post co-solvent treatment and its open pore size effect on pressure-retarded osmosis performance. Macromol Res 24(4):314–322. https://doi.org/10.1007/s13233-­016-­4044-­2 Paul DR, Robeson LM (2008) Polymer nanotechnology: nanocomposites. Polymer 49(15):3187–3204. https://doi.org/10.1016/j.polymer.2008.04.017

254

E. Yilmaz and M. Soylak

Pérez-González A, Urtiaga AM, Ibáñez R, Ortiz I (2012) State of the art and review on the treatment technologies of water reverse osmosis concentrates. Water Res 46(2):267–283. https:// doi.org/10.1016/j.watres.2011.10.046 Phattaranawik J, Jiraratananon R, Fane AG (2003) Heat transport and membrane distillation coefficients in direct contact membrane distillation. J Membr Sci 212(1):177–193. https://doi. org/10.1016/S0376-­7388(02)00498-­2 Pirhashemi M, Habibi-Yangjeh A (2017) ZnO/NiWO4/Ag2CrO4 nanocomposites with pnn heterojunctions: Highly improved activity for degradations of water contaminants under visible light. Sep Purif Technol. https://doi.org/10.1016/j.seppur.2017.11.007001 Pisignano D, Maruccio G, Mele E, Persano L, Di Benedetto F, Cingolani R (2005) Polymer nanofibers by soft lithography. Appl Phys Lett 87(12):123109. https://doi.org/10.1063/1.2046731 Prince JA, Bhuvana S, Anbharasi V, Ayyanar N, Boodhoo KVK, Singh G (2016) Ultra-wetting graphene-based PES ultrafiltration membrane–a novel approach for successful oil-water separation. Water Res 103:311–318. https://doi.org/10.1016/j.watres.2016.07.042 Puguan JMC, Kim HS, Lee KJ, Kim H (2014) Low internal concentration polarization in forward osmosis membranes with hydrophilic crosslinked PVA nanofibers as porous support layer. Desalination 336:24–31. https://doi.org/10.1016/j.desal.2013.12.031 Qing W, Shi X, Deng Y, Zhang W, Wang J, Tang CY (2017) Robust superhydrophobic-­ superoleophilic polytetrafluoroethylene nanofibrous membrane for oil/water separation. J Membr Sci 540:354–361. https://doi.org/10.1016/j.memsci.2017.06.060 Qu X, Brame J, Li Q, Alvarez PJ (2012) Nanotechnology for a safe and sustainable water supply: enabling integrated water treatment and reuse. Acc Chem Res 46(3):834–843. https://doi. org/10.1021/ar300029v Qu X, Alvarez PJ, Li Q (2013) Applications of nanotechnology in water and wastewater treatment. Water Res 47(12):3931–3946. https://doi.org/10.1016/j.watres.2012.09.058 Radjenović J, Petrović M, Ventura F, Barceló D (2008) Rejection of pharmaceuticals in nanofiltration and reverse osmosis membrane drinking water treatment. Water Res 42(14):3601–3610. https://doi.org/10.1016/j.watres.2008.05.020 Rao S, Klimont Z, Smith SJ, Van Dingenen R, Dentener F, Bouwman L et al (2017) Future air pollution in the Shared Socio-economic Pathways. Glob Environ Chang 42:346–358. https://doi. org/10.1016/j.gloenvcha.2016.06.004 Ren J, Zhang Z, Wang M, Guo G, Du P, Li F (2018) Phosphate-induced differences in stabilization efficiency for soils contaminated with lead, zinc, and cadmium. Front Environ Sci Eng 12(2):10. https://doi.org/10.1007/s11783-­018-­1006-­2 Ritala M, Leskelä M (1999) Atomic layer epitaxy-a valuable tool for nanotechnology? Nanotechnology 10(1):19 Rojas-Valencia, M. N. (2011). Research on ozone application as disinfectant and action mechanisms on wastewater microorganisms. Virus, 3, 4-0. Rosegrant MW (1997) Water resources in the twenty-first century: challenges and implications for action, vol 20. International Food Policy Research Institute, Washington. https://doi. org/10.12691/ajwr-­5-­4-­2 Saeijs HL, Van Berkel MJ (1995) Global water crisis: the major issue of the 21st century a growing and explosive problem. Eur Water Pollut Control 5(4):26–40. https://doi.org/10.102 3/A:1006805025176 Sahoo SK, Parveen S, Panda JJ (2007) The present and future of nanotechnology in human health care. Nanomed Nanotechnol Biol Med 3(1):20–31. https://doi.org/10.1016/j.nano.2006.11.008 Sakkayawong N, Thiravetyan P, Nakbanpote W (2005) Adsorption mechanism of synthetic reactive dye wastewater by chitosan. J Colloid Interface Sci 286(1):36–42. https://doi.org/10.1016/j. jcis.2005.01.020 Sánchez O (2017) Microbial diversity in biofilms from reverse osmosis membranes: A short review. J Membr Sci. https://doi.org/10.1016/j.memsci.2017.09.082 Sarikaya M, Tamerler C, Jen AKY, Schulten K, Baneyx F (2003) Molecular biomimetics: nanotechnology through biology. Nat Mater 2(9):577–585. https://doi.org/10.1038/nmat964

6  Nanotechnological Developments in Nanofiber-Based Membranes Used for Water…

255

Savage N, Diallo MS (2005) Nanomaterials and water purification: opportunities and challenges. J Nanopart Res 7(4):331–342. https://doi.org/10.1007/s11051-­005-­7523-­5 Sayed S, Tarek S, Dijkstra I, Moerman C (2007) Optimum operation conditions of direct capillary nanofiltration for wastewater treatment. Desalination 214(1-3):215–226. https://doi. org/10.1016/j.desal.2006.07.014 Schuenemann F, Msangi S, Zeller M (2016) Policies for a sustainable biomass energy sector in Malawi: enhancing energy and food security simultaneously Sen R, Zhao B, Perea D, Itkis ME, Hu H, Love J et al (2004) Preparation of single-walled carbon nanotube reinforced polystyrene and polyurethane nanofibers and membranes by electrospinning. Nano Lett 4(3):459–464. https://doi.org/10.1021/nl035135s Shariful MI, Sepehr T, Mehrali M, Ang BC, Amalina MA (2018) Adsorption capability of heavy metals by chitosan/poly (ethylene oxide)/activated carbon electrospun nanofibrous membrane. J Appl Polym Sci 135(7). https://doi.org/10.1002/app.45851 Sigmund G, Poyntner C, Piñar G, Kah M, Hofmann T (2018) Influence of compost and biochar on microbial communities and the sorption/degradation of PAHs and NSO-substituted PAHs in contaminated soils. J Hazard Mater 345:107–113. https://doi.org/10.1016/j.jhazmat.2017.11.010 Song X, Liu Z, Sun DD (2011) Nano gives the answer: breaking the bottleneck of internal concentration polarization with a nanofiber composite forward osmosis membrane for a high water production rate. Adv Mater 23(29):3256–3260. https://doi.org/10.1002/adma.201100510 Soyekwo F, Zhang Q, Gao R, Qu Y, Lin C, Huang X et al (2017) Cellulose nanofiber intermediary to fabricate highly-permeable ultrathin nanofiltration membranes for fast water purification. J Membr Sci 524:174–185. https://doi.org/10.1016/j.memsci.2016.11.019 Srivastava A, Srivastava ON, Talapatra S, Vajtai R, Ajayan PM (2004) Carbon nanotube filters. Nat Mater 3(9):610–614. https://doi.org/10.1038/nmat1192 Stottmeister U, Wießner A, Kuschk P, Kappelmeyer U, Kästner M, Bederski O et al (2003) Effects of plants and microorganisms in constructed wetlands for wastewater treatment. Biotechnol Adv 22(1):93–117. https://doi.org/10.1016/j.biotechadv.2003.08.010 Sulaiman S, Cieh NL, Mokhtar MN, Naim MN, Kamal SMM (2017) Covalent immobilization of cyclodextrin glucanotransferase on kenaf cellulose nanofiber and its application in ultrafiltration membrane system. Process Biochem 55:85–95. https://doi.org/10.1016/j.procbio.2017.01.025 Sundarrajan S, Ramakrishna S (2007) Fabrication of nanocomposite membranes from nanofibers and nanoparticles for protection against chemical warfare stimulants. J Mater Sci 42(20):8400–8407. https://doi.org/10.1007/s10853-­007-­1786-­4 Sundarrajan S, Balamurugan R, Kaur S, Ramakrishna S (2013) Potential of engineered electrospun nanofiber membranes for nanofiltration applications. Dry Technol 31(2):163–169. https:// doi.org/10.1080/07373937.2012.693144 Tadesse A, Bosona T, Gebresenbet G (2013) Rural water supply management and sustainability: The case of Adama Area, Ethiopia. J Water Resour Protect 5(02):208. https://doi.org/10.4236/ jwarp.2013.52022 Tai MH, Gao P, Tan BYL, Sun DD, Leckie JO (2014) Highly efficient and flexible electrospun carbon–silica nanofibrous membrane for ultrafast gravity-driven oil–water separation. ACS Appl Mater Interfaces 6(12):9393–9401. https://doi.org/10.1021/am501758c Tai MH, Juay J, Sun DD, Leckie JO (2015) Carbon–silica composite nanofiber membrane for high flux separation of water-in-oil emulsion–Performance study and fouling mechanism. Sep Purif Technol 156:952–960. https://doi.org/10.1016/j.seppur.2015.08.008 Tennent H, Moy D, Niu CM (2000) U.S. Patent No. 6,099,960. U.S. Patent and Trademark Office, Washington, DC Ternes TA, Meisenheimer M, McDowell D, Sacher F, Brauch HJ, Haist-Gulde B et  al (2002) Removal of pharmaceuticals during drinking water treatment. Environ Sci Technol 36(17):3855–3863. https://doi.org/10.1021/es015757k Thakur N, Baji A, Ranganath AS (2018) Thermoresponsive electrospun fibers for water harvesting applications. Appl Surf Sci 433:1018–1024. https://doi.org/10.1016/j.apsusc.2017.10.113

256

E. Yilmaz and M. Soylak

Thanuttamavong M, Yamamoto K, Oh JI, Choo KH, Choi SJ (2002) Rejection characteristics of organic and inorganic pollutants by ultra low-pressure nanofiltration of surface water for drinking water treatment. Desalination 145(1-3):257–264. https://doi.org/10.1016/ S0011-­9164(02)00420-­4 Theron J, Walker JA, Cloete TE (2008) Nanotechnology and water treatment: applications and emerging opportunities. Crit Rev Microbiol 34(1):43–69. https://doi. org/10.1080/10408410701710442 Tian M, Qiu C, Liao Y, Chou S, Wang R (2013) Preparation of polyamide thin film composite forward osmosis membranes using electrospun polyvinylidene fluoride (PVDF) nanofibers as substrates. Sep Purif Technol 118:727–736. https://doi.org/10.1016/j.seppur.2013.08.021 Tian M, Wang R, Goh K, Liao Y, Fane AG (2015) Synthesis and characterization of high-­ performance novel thin film nanocomposite PRO membranes with tiered nanofiber support reinforced by functionalized carbon nanotubes. J Membr Sci 486:151–160. https://doi. org/10.1016/j.memsci.2015.03.054 Tiwari DK, Behari J, Sen P (2008) Application of nanoparticles in waste water treatment 1. Upadhyay RK, Soin N, Roy SS (2014) Role of graphene/metal oxide composites as photocatalysts, adsorbents and disinfectants in water treatment: a review. RSC Adv 4(8):3823–3851. https:// doi.org/10.1039/c3ra45013a Valcarcel M, Simonet BM, Cardenas S, Suárez B (2005) Present and future applications of carbon nanotubes to analytical science. Anal Bioanal Chem 382(8):1783–1790. https://doi. org/10.1007/s00216-­005-­3373-­3 Vanangamudi A, Dumée LF, Duke MC, Yang X (2017) Nanofiber Composite Membrane with Intrinsic Janus Surface for Reversed-Protein-Fouling Ultrafiltration. ACS Appl Mater Interfaces. https://doi.org/10.1021/acsami.7b02382 Vital B, Bartacek J, Ortega-Bravo JC, Jeison D (2018) Treatment of acid mine drainage by forward osmosis: Heavy metal rejection and reverse flux of draw solution constituents. Chem Eng J 332:85–91. https://doi.org/10.1016/j.cej.2017.09.034 Vörösmarty CJ, McIntyre PB, Gessner MO, Dudgeon D, Prusevich A, Green P et al (2010) Global threats to human water security and river biodiversity. Nature 467(7315):555–561. https://doi. org/10.1038/nature09440 Wang X, Chen X, Yoon K, Fang D, Hsiao BS, Chu B (2005) High flux filtration medium based on nanofibrous substrate with hydrophilic nanocomposite coating. Environ Sci Technol 39(19):7684–7691. https://doi.org/10.1021/es050512j Wang M, Webber M, Finlayson B, Barnett J (2008) Rural industries and water pollution in China. J Environ Manag 86(4):648–659. https://doi.org/10.1016/j.jenvman.2006.12.019 Wang B, Wu H, Yu L, Xu R, Lim TT (2012) Template-free Formation of Uniform Urchin-­ like α-FeOOH Hollow Spheres with Superior Capability for Water Treatment. Adv Mater 24(8):1111–1116. https://doi.org/10.1002/adma.201104599 Wang J, Luo C, Qi G, Pan K, Cao B (2014) Mechanism study of selective heavy metal ion removal with polypyrrole-functionalized polyacrylonitrile nanofiber mats. Appl Surf Sci 316:245–250. https://doi.org/10.1016/j.apsusc.2014.07.198 Wang J, Wang X, Zhang P, An J, Cao B, Geng Y et al (2016) Thiol-functionalized electrospun polyacrylonitrile nanofibrous membrane for highly efficient removal of mercury ions. Chem Eng Res Des 113:1–8. https://doi.org/10.1016/j.cherd.2016.07.007 Wang Z, Crandall C, Sahadevan R, Menkhaus TJ, Fong H (2017a) Microfiltration performance of electrospun nanofiber membranes with varied fiber diameters and different membrane porosities and thicknesses. Polymer 114:64–72. https://doi.org/10.1016/j.polymer.2017.02.084 Wang Z, Sahadevan R, Yeh CN, Menkhaus TJ, Huang J, Fong H (2017b) Hot-pressed polymer nanofiber supported graphene membrane for high-performance nanofiltration. Nanotechnology 28(31):31LT02. https://doi.org/10.1088/1361-­6528/aa7ba9 Wang D, Lu Q, Wei M, Guo E (2018a) Electrospinning of flux-enhanced chitosan–poly (lactic acid) nanofiber mats as a versatile platform for oil–water separation. J Appl Polym Sci 135(6). https://doi.org/10.1002/app.45830

6  Nanotechnological Developments in Nanofiber-Based Membranes Used for Water…

257

Wang H, Zeng Y, Guo C, Bao Y, Lu G, Reinfelder JR, Dang Z (2018b) Bacterial, archaeal, and fungal community responses to acid mine drainage-laden pollution in a rice paddy soil ecosystem. Sci Total Environ 616:107–116. https://doi.org/10.1016/j.scitotenv.2017.10.224 Wang J, Wang L, Xu C, Zhi R, Miao R, Liang T et al (2018c) Perfluorooctane sulfonate and perfluorobutane sulfonate removal from water by nanofiltration membrane: The roles of solute concentration, ionic strength, and macromolecular organic foulants. Chem Eng J 332:787–797. https://doi.org/10.1016/j.cej.2017.09.061 Wanjale S, Birajdar M, Jog J, Neppalli R, Causin V, Karger-Kocsis J et al (2016) Surface tailored PS/TiO2 composite nanofiber membrane for copper removal from water. J Colloid Interface Sci 469:31–37. https://doi.org/10.1016/j.jcis.2016.01.054 Wei O, Bing L, Fanghua H, Xuelei W, Bobo G, Siyang C (2013) Urban surface-source wastewater treatment system without external power supply based on nanofiber membrane. Patent application number: CN2013108645 Wei G, Yu H, Quan X, Chen S, Zhao H, Fan X (2014) Constructing all carbon nanotube hollow fiber membranes with improved performance in separation and antifouling for water treatment. Environ Sci Technol 48(14):8062–8068. https://doi.org/10.1021/es500506w Westerhoff P, Yoon Y, Snyder S, Wert E (2005) Fate of endocrine-disruptor, pharmaceutical, and personal care product chemicals during simulated drinking water treatment processes. Environ Sci Technol 39(17):6649–6663. https://doi.org/10.1021/es0484799 Woo YC, Tijing LD, Shim WG, Choi JS, Kim SH, He T et  al (2016) Water desalination using graphene-­enhanced electrospun nanofiber membrane via air gap membrane distillation. J Membr Sci 520:99–110. https://doi.org/10.1016/j.memsci.2016.07.049 Woo YC, Chen Y, Tijing LD, Phuntsho S, He T, Choi JS et al (2017) CF4 plasma-modified omniphobic electrospun nanofiber membrane for produced water brine treatment by membrane distillation. J Membr Sci 529:234–242. https://doi.org/10.1016/j.memsci.2017.01.063 Wu J, Di L, Wan L, Xu Z (2011) Glycosylated nanofiber membrane and preparation method and application thereof. Patent application number: CN102115921 (A) Wu N, Wan LY, Wang Y, Ko F (2017) Conversion of hydrophilic SiOC nanofibrous membrane to robust hydrophobic materials by introducing palladium. Appl Surf Sci 425:750–757. https:// doi.org/10.1016/j.apsusc.2017.07.098 www.ahlstrom-­munksjo.com www.donaldson.com www.elmarco.com www.esfiltehno.ee www.espintechnologies.com www.nanoval.de http://technorbital.com www.toray.com www.vilene.co.jp Xu P, Zeng GM, Huang DL, Feng CL, Hu S, Zhao MH et al (2012) Use of iron oxide nanomaterials in wastewater treatment: a review. Sci Total Environ 424:1–10. https://doi.org/10.1016/j. scitotenv.2012.02.023 Xu R, Jiang P, Wei C, Lü Z, Yu S, Liu M, Gao C (2018) Depositing sericin on partially degraded polyamide reverse osmosis membrane for restored salt rejection and simultaneously enhanced resistance to both fouling and chlorine. J Membr Sci 545:196–203. https://doi.org/10.1016/j. memsci.2017.09.073 Xuefen W, Xiong L, Guishan H, Lingdi S, Min W, Xufeng Y, Ce W (2013) Preparation method of electrostatic spinning hydrophobic nanofiber porous membrane for membrane distillation. Patent application number: CN20131202973. Xueqiong Y, Xiaohui Z, Li Z, Junhua C (2016) Method for preparing oil-water separation nanofiber membrane. Patent application number: CN20161402093. Yang HC, Zhong W, Hou J, Chen V, Xu ZK (2017a) Janus hollow fiber membrane with a mussel-­ inspired coating on the lumen surface for direct contact membrane distillation. J Membr Sci 523:1–7. https://doi.org/10.1016/j.memsci.2016.09.044

258

E. Yilmaz and M. Soylak

Yang X, He Y, Zeng G, Chen X, Shi H, Qing D et al (2017b) Bio-inspired method for preparation of multiwall carbon nanotubes decorated superhydrophilic poly (vinylidene fluoride) membrane for oil/water emulsion separation. Chem Eng J 321:245–256. https://doi.org/10.1016/j. cej.2017.03.106 Ying Y, Ying W, Li Q, Meng D, Ren G, Yan R, Peng X (2017) Recent advances of nanomaterial-­ based membrane for water purification. Appl Mater Today 7:144–158. https://doi.org/10.1016/j. apmt.2017.02.010 You H, Li X, Yang Y, Wang B, Li Z, Wang X et al (2013) High flux low pressure thin film nanocomposite ultrafiltration membranes based on nanofibrous substrates. Sep Purif Technol 108:143–151. https://doi.org/10.1016/j.seppur.2013.02.014 Yuan CG, Guo S, Song J, Huo C, Li Y, Gui B, Zhang X (2017) One-step fabrication and characterization of a poly (vinyl alcohol)/silver hybrid nanofiber mat by electrospinning for multifunctional applications. RSC Adv 7(8):4830–4839. https://doi.org/10.1039/C6RA26770J Yuming Z, Lubin Z, Jun Y, Xiaoxia C, Liu Q (2014a) Fe-Mn loaded nanofiber membrane cadmium elimination material and preparation method thereof. Patent application number: CN20131686086 Yuming Z, Lingli M, Lubin Z (2014b) Iron/chitosan/polyoxyethylene composite nanofiber membrane arsenic removal material and electrostatic spinning preparation method thereof. Patent application number: CN20131538561 Yung L, Ma H, Wang X, Yoon K, Wang R, Hsiao BS, Chu B (2010) Fabrication of thin-film nanofibrous composite membranes by interfacial polymerization using ionic liquids as additives. J Membr Sci 365(1):52–58. https://doi.org/10.1016/j.memsci.2010.08.033 Zaki G, Shoeib T (2018) Concentrations of several phthalates contaminants in Egyptian bottled water: Effects of storage conditions and estimate of human exposure. Sci Total Environ 618:142–150. https://doi.org/10.1016/j.scitotenv.2017.10.337 Zander NE, Gillan M, Sweetser D (2016) Recycled PET nanofibers for water filtration applications. Materials 9(4):247. https://doi.org/10.3390/ma9040247 Zhang WL, Wu SX, Ji HJ, Kolbe H (2004) Estimation of agricultural non-point source pollution in China and the alleviating strategies I. Sci Agric Sin 37(7):1008–1017. https://doi.org/10.4236/ jwarp.2009.15041 Zhang L, Aboagye A, Kelkar A, Lai C, Fong H (2014) A review: carbon nanofibers from electrospun polyacrylonitrile and their applications. J Mater Sci 49(2):463–480. https://doi. org/10.1007/s10853-­013-­7705-­y Zhang Q, Wang H, Fan X, Lv F, Chen S, Quan X (2016) Fabrication of TiO2 nanofiber membranes by a simple dip-coating technique for water treatment. Surf Coat Technol 298:45–52. https:// doi.org/10.1016/j.surfcoat.2016.04.054 Zhao S, Zou L, Tang CY, Mulcahy D (2012) Recent developments in forward osmosis: opportunities and challenges. J Membr Sci 396:1–21. https://doi.org/10.1016/j.memsci.2011.12.023 Zhao F, Chen S, Hu Q, Xue G, Ni Q, Jiang Q, Qiu Y (2017a) Antimicrobial three dimensional woven filters containing silver nanoparticle doped nanofibers in a membrane bioreactor for wastewater treatment. Sep Purif Technol 175:130–139. https://doi.org/10.1016/j.seppur.2016.11.024 Zhao J, Lu Z, He X, Zhang X, Li Q, Xia T et  al (2017b) One-Step Fabrication of Fe(OH)3@ Cellulose Hollow Nanofibers with Superior Capability for Water Purification. ACS Appl Mater Interfaces 9(30):25339–25349. https://doi.org/10.1021/acsami.7b07038 Zhong LS, Hu JS, Liang HP, Cao AM, Song WG, Wan LJ (2006) Self-Assembled 3D flowerlike iron oxide nanostructures and their application in water treatment. Adv Mater 18(18):2426–2431. https://doi.org/10.1002/adma.200600504 Zhou FL, Gong RH (2008) Manufacturing technologies of polymeric nanofibres and nanofibre yarns. Polym Int 57(6):837–845. https://doi.org/10.1002/pi.2395 Zhu H, Jia Y, Wu X, Wang H (2009) Removal of arsenic from water by supported nano zero-­ valent iron on activated carbon. J Hazard Mater 172(2):1591–1596. https://doi.org/10.1016/j. jhazmat.2009.08.031

6  Nanotechnological Developments in Nanofiber-Based Membranes Used for Water…

259

Zhu A, Rahardianto A, Christofides PD, Cohen Y (2010) Reverse osmosis desalination with high permeability membranes—cost optimization and research needs. Desalin Water Treat 15(1–3):256–266. https://doi.org/10.5004/dwt.2010.1763 Zhu LW, Zhou LK, Li HX, Wang HF, Lang JP (2013) One-pot growth of free-standing CNTs/ TiO2 nanofiber membrane for enhanced photocatalysis. Mater Lett 95:13–16. https://doi. org/10.1016/j.matlet.2013.01.004 Zong X, Ran S, Kim KS, Fang D, Hsiao BS, Chu B (2003) Structure and morphology changes during in  vitro degradation of electrospun poly (glycolide-co-lactide) nanofiber membrane. Biomacromolecules 4(2):416–423. https://doi.org/10.1021/bm025717o Zularisam AW, Ismail AF, Salim R (2006) Behaviours of natural organic matter in membrane filtration for surface water treatment—a review. Desalination 194(1-3):211–231. https://doi. org/10.1016/j.desal.2005.10.030

Chapter 7

Fe-Based Nanomaterials for Removing the Environmental Endocrine Disrupting Chemicals in Water: A Review Rong Cheng, Mi Kang, Lei Shi, Jin-lin Wang, Xiang Zheng, and Jian-long Wang

Abstract  As a kind of emerging contaminants, environmental endocrine disrupting chemicals (EEDs) have gained issue of increasing concern due to their biological accumulation and human endocrine disruption. And the trace level and rich diversity of EEDs in the water environment are the main obstacles for removing EEDs. Fe-based nanomaterials, as a new kind of functional materials, have been widely applied into the adsorption and degradation of EEDs in water due to their facile preparation, satisfied nanostructure and outstanding catalytic oxidation performance. In this article, Fe-based nanomaterials with different morphologies and structures, including nanoscale zero-valent iron (nZVI), Fe3O4 nanoparticles (NPs), Fe2O3 NPs and other novel nanomateials, were introduced briefly. The preparation and characterization methods for different Fe-based nanomaterials were also covered. The removal performance of EEDs by various Fe-based nanomaterials in different reaction systems were well summarized as well as the degradation mechanisms including photocatalytic, Fenton and persulfate oxidation. The limitations and advantage strategies of the commonly used Fe-based nanomaterials were also discussed, and some new research directions in the removal of EEDs were proposed according to the new-found properties of Fe-based nanomaterials. Keywords  Fe-based nanomaterials · EEDs · nZVI · Fe3O4 · Fe2O3 · Photocatalyst · Fenton · FeOOH · MOF · Iron oxide

R. Cheng (*) · M. Kang · L. Shi · J.-l. Wang · X. Zheng (*) School of Environment and Natural Resources, Renmin University of China, Beijing, China e-mail: [email protected]; [email protected]; [email protected]; [email protected] J.-l. Wang Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, China e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_7

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7.1  Introduction 7.1.1  Environmental Endocrine Disrupting Chemicals (EEDs) Starting from the report about the residual of steroids in classical urban sewage treatment plant, the environmental endocrine disrupting chemicals (EEDs) have gained issue of increasing concern due to their trace level, bio-refractory, biological accumulation effect, human endocrine disruption (Gore et  al. 2015; Diamanti-­ Kandarakis et al. 2009; Stumm-Zollinger and Fair 1965). Many endocrine system diseases have been reported to be related with EEDs, such as: i) obesity, diabetes and cardiovascular diseases, ii) female and male reproductive health, iii) hormone-­ sensitive cancers in females, iv) prostate gland and thyroid disruption in male, and v) neurodevelopment and neuroendocrine systems (Gore et  al. 2015; Diamanti-­ Kandarakis et al. 2009). The U.S. Environmental Protection Agency (EPA) has defined the EEDs as “an exogenous agent that interferes with synthesis, secretion, transport, metabolism, binding action, or elimination of natural blood-borne hormones that are present in the body and are responsible for homeostasis, reproduction, and developmental process.” (Diamanti-Kandarakis et al. 2009) Up to now, no official screening methods or toxicity testing strategies about EEDs have been fully accepted by scientific community (Snyder et al. 2003). Numerous kinds of natural and artificially synthesized organic compounds undefined appearing in the environment have considered suspicious as potential EEDs. Besides, the existing EEDs proved by some reports are still controversial (Chang et al. 2009). Generally, the EEDs contain pharmaceutical and personal care products (PPCPs), phthalic acid esters (PAEs), pesticides, natural hormones and steroids, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (Ahmed et al. 2017; Gore et al. 2015; Liu et al. 2009; Chang et al. 2009). The classifications of EEDs are summarized in Table 7.1 and Table 7.1  Examples of typical EEDs classification Class Antibiotic

Compound Structure Amoxicillin

Bisphenols

Bisphenol A

Steroids

Ethinyl estradiol

Class Phthalic acid esters

Compound Structure Diethyl phthalate (DEP) Organochlorine DDT pesticides Stimulant

Caffeine

Dioxin Polycyclic aromatic hydrocarbon

Herbicide

Atrazine

Surfactant

Polychlorinated PCBs biphenyls

PFOA

PFOA Perfluorooctanoic acid, PCBs Polychlorinated biphenyls

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some typical EEDs are used as model compounds (Ahmed et al. 2017; Gore et al. 2015; Liu et al. 2009; Chang et al. 2009). Currently, EEDs have been widely detected in groundwater, surface water, discharge wastewater and excess sludge, seawater, and the major sources of these EEDs in freshwater ecosystems are reported to be urban sewage treatment plants (Ruhí et al. 2016; Bolong et al. 2009). EEDs cannot be removed efficiently by conventional coagulation, filtration, precipitation separation technologies because of their trace level (about μg·L−1 or ng·L−1), ubiquitous presence, and wide variety (Chang et al. 2009). Many treatment methods such as adsorption, advanced oxidation processes (AOPs), membrane process, ion exchange as well as biological treatment have been studied in order to enrich or transform them into low toxic or nontoxic products which have shown superior removal efficiencies (Pan et al. 2014; Bastami and Entezari 2012; Xu and Wang 2011; Cheng et al. 2010; Yoon et al. 2006; Joss et al. 2005; Kimura et al. 2004). Researches have shown the limitations of biological treatment in removing EEDs like activated sludge process and biofiltration process (Chang et al. 2009; Joss et al. 2005). Then, biological treatment is not the suitable way to clean up EEDs from waste water. Nanofiltration (NF), ultrafiltration (UF) and reverse osmosis (RO) have been reported to reject several kinds of EEDs with a rejection of 57 ~ 91% (Yoon et al. 2006; Kimura et al. 2004). And membrane properties such as pore size, charge and hydrophobicity have a huge impact on the removal efficiency of EEDs. Membrane process may not be the first choice for removing EEDs in consideration of the trace level concentration of EEDs and big energy consumption of membrane process (Chang et al. 2009). Adsorption, with the advantage of simple access and high efficiency, has been used to remove EEDs with different kinds of adsorbents such as Fe3O4 nanoparticles, activated carbon (AC), metal organic framework materials (MOF), graphene, molecularly imprinted polymer (MIP) and so on (Boruah et  al. 2017; Liu et  al. 2017a, b; Farmany et  al. 2016; Liu et  al. 2015; Chang et  al. 2011). Currently, adsorption of EEDs is mainly focused on two aspects. One is the improvement of the adsorption capacities by synthesizing the adsorbents with suitable size and/or modifying the specific functional groups onto the adsorbents, such as the Pd/ Fe-Fe3O4@MWCNTs nanomaterials and Fe3O4/graphene nanocomposite (Boruah et  al. 2017; Xu et  al. 2016). The other research aspect is the trace detection by modifying the base materials with different MIP according to EEDs, which can be used as extractant in chromatographic determination (Li et  al. 2016; Liu et  al. 2015). The Fe-based nanomaterials can be used in both of the two aspects in the adsorption of EEDs, and Fe3O4 and γ-Fe2O3 composites are the representative substances. AOPs, generally including Fenton/Fenton-like method, ozone, UV/visible light photocatalysis as well as persulfate oxidation, are effectively used in the degradation of EEDs (Lee et al. 2017; Xia and Lo 2016; Tan et al. 2014; Yang et al. 2010; Cheng et al. 2010). At present, these AOPs are aimed to generate reactive oxygen species (ROS) such as •OH, •SO4−, •O2H and other radicals, which have attracted a continuing interest because of their excellent abilities to oxide organic compounds

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including EEDs in aqueous phase. And the degradation efficiency is generally positive correlation with the oxidation power of ROS (Lee et al. 2017). In general, the removal efficiencies of the target EEDs are greatly affected by their chemical structure.

7.1.2  Fe-Based Nanomaterials It is still uncertain whether nanometer era is coming, but it is clear that the unusual properties of nanomaterials have been changing all aspects of our society from industry to civil. Among these, with the increasing requirement of clean water by people, nanotechnology used for water clean-up is placed with great expectation. Various nanomaterials and nanotechnology have been applied to projects for environmental remediation now (Mueller et al. 2012). Iron, as the most plentiful transition metal, has been widely used in modern society. The beginning of engineered Fe-based nanomaterials for environmental remediation came with an experimental discovery, where researchers found that the nanoscale zero-valent iron (nZVI) could change the structure of a group of groundwater contaminants (Wang and Zhang 1997). In recent decades, nZVI is commonly used for in-situ remediation of soil and groundwater in the United States and Europe with the fastest development among the Fe-based nanomaterials (Han et al. 2016; Mueller et al. 2012). Numerous studies have been devoted to the synthesis, physicochemical properties, and the stability and mobility of nZVI. Up to now, nZVI and its composites have been commonly used in removing a wide range of organic and inorganic pollutants, such as halogenated aromatics, non-metal inorganic species (NO2−, NO3−, BrO3−), and heavy metals in aqueous solutions (Yan et al. 2013; Ramos et al. 2009). The most common use of pristine nZVI is the dehalogenation which could substitute the halogen atoms of halogenated hydrocarbons with active hydrogen (Singh and Bose 2016; Cheng et al. 2015; San Roman et al. 2013; Zhang et al. 2011). Another application of pristine nZVI is denitration which refers to the reduction of -NO2 by active hydrogen (Shirazi et al. 2013; Fang et al. 2011; Ghauch et al. 2009). EEDs like organochlorine pesticides (DDT, chlordane, etc.) and nitro-substituted aromatics (carbamazepine, amoxicillin, etc.) can be degraded by pristine nZVI to some extent. However, the tendency of agglomeration and oxidation of nZVI limit the further use of nZVI until the presence of stabilized nZVI supported by organic or inorganic support materials (Zhao et al. 2016). The novel stabilized nZVI is introduced to AOPs as heterogeneous catalyst to degrade the emerging pollutants including EEDs. For example, iron in the interior of the catalyst could effectively reaction with H2O2 to produce ROS under a wider pH range without iron mud generation (Garrido-Ramirez et al. 2010). The application of nZVI in reduction and oxidation especially in heterogeneous catalysis gives a promising way for the groundwater remediation.

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Nanoscale iron oxides including Fe3O4 nanoparticles (NPs) and Fe2O3 NPs, as one kind of the most attractive functional materials, are another kind of outstanding Fe-based nanomaterials. Two prominent characteristics of nanoscale iron oxides are the magnetism of Fe3O4 NPs and γ-Fe2O3 NPs and the heterogeneous catalytic activity of Fe3O4 NPs and Fe2O3 NPs as well as the performance of nanomaterials (Munoz et  al. 2015; Pouran et  al. 2014; Tao et  al. 2013). Adsorption is one of the most important applications of magnetic nanoscale iron oxides and their composites. The magnetism enables the separation of adsorbents from aqueous solutions, and the nano size as well as the modified functional groups of adsorbents improves the adsorption capacities for contaminants. The application of magnetic NPs in Fenton-­ like oxidation starts a new generation of catalysts. With the two kinds of valences Fe (II) and Fe (III), Fe3O4 NPs could catalyze H2O2 directly, which improves the production of hydroxyl radicals (He et al. 2016; Pouran et al. 2014). As for the photocatalytic properties, Fe3O4 NPs often just play a role of supporting and separating (Kumar et al. 2018; Gao et al. 2017). However, α-Fe2O3 and γ-Fe2O3, with the band gaps of 2.2 and 2.3 eV respectively and the property of n-type semiconductor, are considered to have photocatalytic ability theoretically (Wu et  al. 2015; Wei et al. 2014). The trace level of concentration and rich diversities of EEDs in the water environment are the main obstacles for removing EEDs. Some routine reviews have summarized the physical, chemical and biologic ways to remove EEDs (Ahmed et al. 2017; Liu et al. 2009; Chang et al. 2009). As mentioned above, Fe-based nanomaterials have been widely used in reducing the potential toxicity of new organic pollutants; however, there are few reviews on the removal of EEDs by Fe-based nanomaterials. The purpose of this review is to provide a summary of Fe-based nanomaterials that have been used in the removal of EEDs along with the removal mechanism of EEDs. Specifically, the article also provides the limitations of commonly used Fe-based nanomaterials and some new research directions according to the new-found properties of Fe-based nanomaterials.

7.2  Nanoscale Zero-Valent Iron and Its Composites As reported, nZVI is one of the most technical feasible and economical ways for the environmental remediation (Yan et al. 2013). It has been commonly used for the in-situ repair of soil and groundwater in the United States and Europe. When it comes to detailed relevant pollutants such as EEDs, nZVI has been applied to degrading pesticides, antibiotic, polychlorinated biphenyls, bisphenol, estrogens and other contaminants (Karim et al. 2017; Li et al. 2017; Ma et al. 2016; Sun et al. 2013; Shih et al. 2011).

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7.2.1  Preparation and Characterization 7.2.1.1  Preparation of nZVI Despite the numerous existing methods, the preparation methods of nZVI can be classified as bottom-up and top-down methods which are shown in Fig. 7.1. The specific methods contain chemical reduction, thermal reduction, electrochemical method, cluster deposition as well as high energy ball milling. However, nZVI is mostly synthesized by chemical reduction, which is also adopted by the most research laboratories (Lefevre et al. 2016; Crane and Scott 2012; Hwang et al. 2011; Wang et al. 2009a, b; Qiang et al. 2006). According to the reaction Eqs. (7.1) or (7.2), the advantage of this reaction process is to adjust the physical properties of nZVI with different concentrations of raw materials and reaction time (Hwang et al. 2011; Chen et al. 2011). High reaction rate and high concentrations of raw materials produce smaller nZVI particles but poor crystallinity of the particles (Hwang et al. 2011).

4Fe 3  3BH 4   9H 2 O  4Fe 0  3H 2 BO3   12H   6H 2  Fe

2







 2BH 4  6H 2 O  Fe  2H 2 BO3  2H  7H 2  0

(7.1) (7.2)

The bottom-up approach is aimed to form nanosized structures with the deposition of atom or molecules. For example, Fe atoms are sputtered into the cluster growth chamber continuously by high-pressure inert gas and cooled by cooling water then (Qiang et al. 2006). In this way, nZVI is formed in the chamber with a mean size of 2 ~ 100 nm. Inevitably, a large number of energy is consumed in the heating and cooling process of Fe atoms evaporating and depositing. And the strict operation condition and complex equipment as well as low yield are also the limitations for its long-term application. Other bottom-up approaches, such as thermal reduction, where nZVI is obtained by reducing iron oxide or Fe2+ salt under high temperature reducing gas (such as H2,

Fig. 7.1  The two kinds of ways to synthesize nZVI

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CO2, CO) (Bystrzejewski 2011; Hoch et al. 2008). A novel technology to prepare nZVI is combining electrochemical and ultrasonic methods according to the following reaction Eq. (7.3) (Chen et al. 2004). Fe(CO)5 have been reported to synthesis nZVI (10 ~ 20 nm) under high-intensity ultrasonic waves if ignoring its high toxicity, either. Fe 3  3e   stabilizer  nFe 0



(7.3)

The top-down method is the process of striking and breaking the micro iron to smaller particles using much heavier and larger milling balls with high energy, which is achieved completely by mechanical method (Li et al. 2009; Kong et al. 2008). However, considerable lattice dislocations, vacancies and stresses during the prolonged milling introduce the particles with irregular shapes and high level of defects (Kong et al. 2008). Considering the development of clean and green synthesis, a most environment-­ friendly reagent to reduce Fe ion is polyphenolic plant extracts (Hoag et al. 2009). Without using surfactants or polymers to inhibit the agglomeration and oxidation of pristine nZVI, the spontaneous reaction between tea polyphenols and Fe(NO3)3 occurs with a large amount of hydroxyl and phenol groups present in this compound (Yan et al. 2013; Hoag et al. 2009). Consequently, the materials afford a better application in the remediation of actual water environment. And a briefly summary comparison of the various methods for preparing nZVI is shown in Table 7.2. Nanomaterials have the characteristics of small size, high surface energy and quantum size effect. And because of the presence of intrinsic magnetic interactions and Van-der-Waals-Bindung forces with environmental medium, it is easy to aggregate and pore clog for nZVI which greatly limits the mobility of nZVI in subsurface migration (Schrick et al. 2004). In order to solve the problem of particle aggregation and corrosion, many polyelectrolytes/surfactants or support materials (creating a network) have been demonstrated (Zhao et al. 2016). Table 7.2  Summary comparison of the various methods for preparing nZVI Method Chemical reduction Cluster deposition Thermal reduction Electrochemical method High-intensity ultrasonic High-energy ball milling Tea polyphenols reduction

Precursor Fe2+/Fe3+ (aq) Iron Fe2+/Fe3+ (s) Fe3+(aq)

Size BET (nm) (m2·g−1) References 10–100 17.9 ~ 67.5 Liu and Zhang (2014), Shih et al. (2011), Wang et al. (2009a, b) 2–100 Bystrzejewski (2011), Wang et al. (2009a, b) Qiang et al. (2006) 20–50 29 Hoch et al. (2008), Nurmi et al. (2005) 1–100 25.4

Fe(CO)5

10–20

Micro Fe

10–50

Fe(NO3)3

5–15

Chen et al. (2004) Yan et al. (2013)

17–39

Li et al. (2009), Kong et al. (2008) Hoag et al. (2009)

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Surfactants are well accepted that their steric hindrances counteract the intrinsic magnetic interactions between nZVI particles and improve the colloidal stability of nZVI (Crane and Scott 2012). Support materials, such as diatomite (Sun et al. 2013; Dror et al. 2012), organobentonite (Zhang et al. 2011; Li et al. 2011a, b), poly acrylic acid (Lin et  al. 2010), carboxymethyl cellulose (Bhattachatjee et al. 2016; Lin et al. 2010;), activated carbon (Chang et al. 2011), polyvinylpyrrolidone (Chen et  al. 2011), graphene family nanomaterials (Chen et  al. 2016; Liu et al. 2016) and other stabilizers, are chosen to create a network which could be adhered by nZVI. Biosurfactant rhamnolipid and polymer carboxymethylcellulose (CMC) are applied to modifying pristine nZVI, and it is proved that the nZVI modified with rhamnolipid are more stable than that with CMC, but lower dechlorination efficiency of trichloroethylene was obtained (Bhattachatjee et al. 2016). 7.2.1.2  Characterization of nZVI To completely understand the processes involving nZVI, it is necessary to know the chemical and physical properties of the particles such as the size, the shape, the structure, the surface characteristics, the surface coating if existing, and so on (Fig.  7.2). Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) are usually used to obtain the morphology and structure of nZVI (Karim et  al. 2017). Electron microscopic technique is indispensable to study the morphology, dispersion state and reaction performances of nZVI with contaminants. The nZVI

Fig. 7.2  The main purposes for the characterization of nZVI and its composites

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prepared by chemical reduction and high-energy ball milling appears as a smooth globule with a diameter of 10 ~ 100 nm and 10 ~ 50 nm, respectively (Li et al. 2009; Ramos et al. 2009) (Table 7.2). While there is more angular shape on the surface of nZVI prepared by thermal reduction method (Yan et al. 2013; Nurmi et al. 2005). The particle size distribution is usually obtained by gathering the statistics of SEM/TEM images. Without any stabilizing chemicals, the nanoparticles generally trend to form linear or fractal aggregates (Yan et  al. 2013). Besides, energy dispersive X-ray (EDS) attached to the SEM/TEM is also used to calculate the element composition of nZVI compounds before and after reaction with pollutants which is quite vital for the stabilized nZVI. A novel technology named Scanning transmission electron microscopy (STEM) is applied to simultaneously characterizing the surface physical imaging and chemical identification of nZVI at atomic resolution (Liu and Zhang 2014). While fresh nZVI will be oxided instantly under air, a core-shell structure of nZVI with spherical shape could be observed through the STEM (Wang et  al. 2009a, b). The core-­shell structure allows the nanoparticle to possess the reduction properties of Fe0 and adsorptive and coordinative abilities of iron oxides (Liu and Zhang 2014). The oxide shell, which correlates with the Fe0 surface chemical, has been proved to be iron oxide with a thickness of approximately 3 nm (Yan et al. 2013; Ramos et al. 2009). The evolution process of the core-shell structure depends much on the environmental conditions, especially oxygen. The nanoparticles could maintain its core-­shell structure for quite a long time (72  h) under anoxic condition, but evolves quickly under oxic conditions until the nanomaterial evolves into γ-FeOOH and Fe3O4/γ-Fe2O3, a structure of flaky and/or acicular (Liu et al. 2017a, b). While SEM/TEM pictures provide visual evidence of nZVI at microscale, it is limited in two-dimensional scale. However, BET exhibits the reliable approach to get the overall information of nZVI which is specific surface area. A comparable specific surface area of nZVI is 67.51 ± 0.35 m2·g−1 with particle size distribution from 5 nm to 20 nm when using 90% ethanol aqueous as the solvent in the Fe3+/ (BH4−) system (Wang et al. 2009a, b). Except for the surface characteristics, the grain size and crystal structure of nZVI are always determined by XRD based on Scherrer’s formula. Fresh nZVI from BH4− reduction is suggested to be polycrystalline bcc Fe(0), while more depth analysis of X-ray absorption spectroscopy shows that the Fe0 core from solutionderived nZVI is more disordered, due to the existence of a glassy metal iron phase (Yan et al. 2012, 2013). The glassy metal iron phase is directly correlated with the produce of activate hydrogen by nZVI, which may be responsible for the higher dechlorination and hydrogenation efficiency of solution-derived nanoparticles than the highly crystalline particles obtained by thermal reduction method (Yan et al. 2013).

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7.2.2  Role in Removal of EEDs 7.2.2.1  Pristine nZVI System As mentioned earlier, the nZVI has both of the reduction property of Fe0 and adsorptive and coordinative abilities of iron oxides (Liu and Zhang 2014). Fe0 is a strong reducing agent in water according to Eq. (7.4) and (7.5), which makes Fe0 a reducing agent with many redox-labile substances (Matheson and Tratnyek 1994). A comprehensive review about the functional groups of EEDs that involved in the reaction with pristine nZVI has been summarized in Table 7.3. Cl− is the main reaction site, and benzene ring, C-N bond, amino as well as nitro could also be degraded by nZVI. But the main reductive effect of nZVI is dehalogenation and denitration shown in Fig. 7.3 (Liu et al. 2017a, b; Yan et al. 2013; Brewster 1954).

Fe 0  Fe 2   2e  E 0  0.44 V Fe

2

3



 Fe  e E  0.77 V 0

(7.4) (7.5)

An interesting functional group is the nitro groups (-NO2) or amino (-NH2) connecting with C atom. On the one hand, -NO2 in the nitro aromatic compounds could be reduced to -NH2 by proton transfer in nZVI/water system according to Fig. 7.3, such as tetracycline (TC), metronidazole (MNZ) (Dong et  al. 2018; Chen et  al. 2012; Chen et  al. 2011). However, the real reduction pathway of nitro aromatic compounds by nZVI depends on its structure and the relative position of amino groups to the other substitutions. For example, tetracycline, an antibiotic of non-­ halogenated hydrocarbon, could be partially degraded by nZVI(Dong et al. 2018; Chen et al. 2011). However, there are rare reports that prove the detailed mechanism of TC degradation by nZVI, except for some by-products from mass spectrometry (Dong et al. 2018; Chen et al. 2011). Possible reasons are related to the low C-N bond energy and free radicals from nZVI. In addition, researchers have used zeolite, graphene oxide and starch supported nZVI to adsorb TC, which show comparable adsorption capacity (Guo et al. 2017; Wei et al. 2017; Fu et al. 2015). Trishikhi have summarized the three reduction pathway of removing -NO2/-NH2: i) nitro-reduction (Fig.  7.3), ii) the cleavage of -C-N bond (low bond energy), iii) denitration of the -NO2 during MNZ by nZVI. When there is no -Cl or -NO groups, according to the research of Karim et al., the degradation of EE2 by commercial stabilized nZVI was mainly attributed to active hydrogen at pH 3, 5, 7 under anaerobic conditions (Karim et al. 2017). And the removal efficiency of EE2 was lower at pH 7 than that of pH 3 and 5. Under anaerobic conditions, direct and indirect reactions occurred on the nZVI surface during the reduction process at the three different pH, in which indirect reaction occurred when the chemisorbed hydride complexes were generated on the surface of nZVI according to Fig. 7.3. The research also proved the phenomenon that no oxidizing or reducing radicals were generated by using nZVI with scavengers to degrade EE2 in nitrogen-purged reactors (Karim et  al. 2017). In addition, the

Table 7.3  The groups that could be degraded by pristine nZVI Reaction groups Ph-OH

Materials nZVI

Pollutants Chemical structure EE2

nZVI

CBZ

Diatomite-­ supported nZVI

Simazine

-Cl

PVP-nZVI

TC

nZVI

PCP

-CH3 -C-N -OH -Cl

nZVI

ES-1(2)

-Cl

H* (e−)

nZVI

Lindane

-Cl

+ e−

nZVI

AMX

-NH2 -COOH -C-N β-lactams

AMP

Mechanism References •OH Karim et al. (2017), Jarosova et al. (2015) Shirazi et al. (2013) H* (e−)

Sun et al. (2013) Chen et al. (2011) Li et al. (2011a, b), Shih et al. (2011), Cheng et al. (2010) Singh and Bose (2017, 2016) San Roman et al. (2013), Chang et al. (2011), Li et al. (2011a, b) Ghauch et al. (2009)

nZVI-CTMA- Atrazine Bent

-Cl

+ e−

Zhang et al. (2011)

nZVI

MNZ

-C-N -NO2

•OH

nZVI

TCBPA

-Cl

H*

Chen et al. (2012), Fang et al. (2011) Li et al. (2017)

TBBPA

-Br

H*

BDE 209

-Br

H* (e−)

Biomass carbon and nZVI

Fu et al. (2016)

EE2: 17a-ethinylestradiol, CBZ: carbamazepine, TC: tetracycline, PCP: pentachlorophenol ES-1(2): endosulfan isomers, AMX: amoxicillin, AMP: ampicillin, MNZ: metronidazole TBBPA: tetrabromobisphenol A, TCBPA: tetrachlorobisphenol A BDE 209: polybrominated diphenyl ethers

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Fig. 7.3  The mechanism of direct dehalogenation and denitration of nZVI Table 7.4  The equations in homogeneous Fe2+/H2O2 system Equations 2

3

Fe  H2O2  Fe  OH  •OH 

Fe3  H2O2  Fe2  •O2H  H Fe2  HO•  Fe3  OH

Rate constant (M−1 s−1) 63 ~ 76 0.001 ~ 0.01

H2O2  HO•  HO2 • H2O

3.2 × 108 3.3 × 107

HO • HO•  H2O2

6 × 109

References He et al. (2016), Yan et al. (2013), Garrido-Ramirez et al. (2010)

degradation of EE2 in water with dissolved oxygen was attributed to reactive nonspecific oxidant like •OH, shown as Eq. (7.6) (Jarosova et  al. 2015; Mylon et al. 2010).

Fe 0  s   O2  aq   2H   Fe 2   aq   H 2 O2  aq 

(7.6)

7.2.2.2  nZVI/H2O2 System Classical Fenton oxidation method chooses Fe2+ as the homogeneous catalyst to generate hydroxyl radicals (•OH), which requires low pH value (lower than 4) and generates much iron mud (Karim et al. 2017). In theory the organic compound will be completely oxided into CO2 and H2O by the •OH from Fe2+/H2O2 system without any self-consumption. However, researches have proved that the large number of generating •OH will be consumed not only by organic compounds but also by Fe2+/ H2O2 themselves according to Table 7.4 (Bokare and Choi 2014). A new idea to improve the oxidation efficiency of Fenton reaction is to choose nZVI as the heterogeneous phase activator classified as “Fenton-like” method. Specifically, the high specific surface area and small size let the nZVI contact or adsorb contaminants easily, which accelerates the oxidation process. The nZVI/

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Fig. 7.4  The mechanism of H2O2 catalyzed by nZVI

H2O2 Fenton-like reaction could be classified into two conditions. One is the reactions occurring in the surface of nZVI, and the other is the dissolved Fe2+/Fe3+ inducing homogeneous Fenton reactions which acts the same mechanism with classical Fenton method, which are shown in Fig. 7.4 (He et al. 2016). Table 7.5 has summarized the researches of EEDs that are degraded by nZVI/ H2O2 system. Typically, 4-chloro-3-methyl phenol (CMP), a kind of chlorophenol preservatives, was degraded by nZVI/H2O2 system (Xu and Wang 2011). The effect of pH value, initial concentrations of H2O2 and CMP, dose of nZVI were studied, while the lower pH and initial concentration of CMP could significantly enhance the degradation rate. The high BET makes nZVI adsorb the CMP molecules to a certain extent, which impedes the release of Fe2+ and •OH according to Table 7.4 (Xu and Wang 2011). Although the decreased efficiency of CMP at high pH (6.1) was related to the iron corrosion, the activity of nZVI was still higher than that of several other heterogeneous catalysts in Fenton-like reaction (Xu and Wang 2011). The same result was obtained when Karim et  al. degraded EE2 using nZVI/H2O2 system at pH 7 (Karim et al. 2017). Meanwhile, the research had proved that neither •OH nor •O2− played a role under this condition. Possible reason proposed was the free radicals such as Fe(IV) or Fe(IV)O2+ when the concentration of Fe2+ was low according to Eq. (7.7) (Karim et al. 2017)

Fe 2   H 2 O2  Fe  IV  O2   H 2 O pH  7

(7.7)

Stabilized nZVI provides several possibilities in Fenton-like reaction (Daneshkhah et al. 2017; Ma et al. 2016). Ma et al. synthesized the acid leached diatomite supported nZVI grafted with 3-Mercaptopropyl trimethoxysilane (M-nZVI-DaHT) based on the assumption of generating acid and ferrous ions in situ in Fenton-like reaction (Ma et al. 2016). BPA of 50 mg·L−1 was chosen to be degraded by M-nZVI-DaHT/H2O2 system in natural pH, and the result showed that a removal efficiency of almost 100% was obtained when pH value was about 3.5 (Ma et al. 2016).

Pentachlorophenol

Chlorpheniramine

4-chloro-3-methyl phenol

nZVI

nZVI

nZVI

300, 6000 102 ~ 680

3 ~ 9

20 ~ 204

0.34 ~ 6.8

100, 500, 1000

5.75

3 ~ 6

2 ~ 5

–

Initial Initial C[H2O2] (mg·L−1) pH 7.5 10, 25

1, 3, 5

50

50 ~ 150

5 ~ 30

50

Initial C[target] (mg·L−1) 5

0.5, 1, 1.5

0.2, 2

0.1 ~ 0.6

0.01 ~ 0.03

–

Catalyst dosage (g·L−1) 0.01, 0.02

≤ 63% Degradation followed two-stage first-order kinetic. Generate acid and – ferrous ions in situ – Removal efficiency was 55.16% (3 mg·L−1) in tap water

a

TOC removal efficiency ≤ 78.5%

Highlights No influence in different matrixs. (distilled water and groundwater) Efficiency: nZVI > ZVI – Fe3O4 was the main products. Complete dechlorination ≤ 21%

M-nZVI-DaHT: nZVI and acid leached diatomite composites grafted with 3-Mercaptopropyl trimethoxysilane

a

M-nZVI-­ Bisphenol A DaHT Sepiolite-­ Metoprolol nZVI

Pollutants Carbamazepine

Materials nZVI

Chemical structure

Table 7.5  Summary of the EEDs that are degraded by nZVI/H2O2 system

Ma et al. (2016) Daneshkhah et al. (2017)

Xu and Wang (2011)

Wang et al. (2016)

Cheng et al. (2015)

References Shirazi et al. (2013)

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7.2.2.3  Other nZVI Heterogeneous Catalytic Systems As heterogeneous catalysts, nZVI and its composites have also been used in O3, UV, and S2O82− oxidation systems for the degradation of EEDs. Research has revealed that nZVI/TiO2 composite could enhance the photocatalytic ability for degrading trichloroethylene compared to nanoscale TiO2 (Huang et al. 2007). Similarly, Ma et  al. synthesized the nZVI/TiO2 nano-tubes with galvanostatic electrodeposition process and used the nano-tubes in visible light photocatalytic system for the degradation of 4-chlorphenol, which got the same result (Ma et al. 2017). But the paper also pointed out that the main reason for the increasing photocatalytic performance was correlation with the by-products from iron corrosion like α-Fe2O3 (Ma et al. 2017). Organic compounds can be degraded by ozone through direct reaction with molecular ozone and indirect reaction with generated ROS, while pristine iron nanoparticles and their oxidation products could accelerate the generation of ROS (Derco et al. 2015). Derco et al. studied the removal efficiencies of five organochlorine pesticides by O3/nZVI, nZVI alone, O3 alone and O3/UV system., and tThe result showed an obvious increasing of removal efficiency and a clear reduction of the reaction time by O3/nZVI system (Derco et al. 2015). However, the research also revealed that the increasing of ROS in O3/nZVI system was related to iron oxide (Derco et al. 2015). Persulfate oxidation is similar to Fenton method but with more catalyst selections and higher oxidation ability (Hussain et al. 2017). On the one hand, SO4−• with a higher redox potential (E0  =  2.5  ~  3.1  V) compared to that of •OH (E0  =  1.8  ~  2.7  V) is more suitable for the degradation of EEDs (Hussain et  al. 2017). On the other hand, longer half-life and wider range of adapted pH value make SO4−• have a broad application prospects than •OH (Hussain et al. 2017). In view of this, the mechanism of S2O82− activating by nZVI to generate SO4−• is shown in Table 7.6 (Hussain et al. 2017). Besides, nZVI, biochar supported nZVI (BC/nZVI), nZVI-Ag and other materials have been synthesized to degrade EEDs like nonylphenol, 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) and 4-chlorophenol in persulfate oxidation processes (Hussain et  al. 2017; Wang et  al. 2017; Silveira et al. 2017). And all researches revealed that SO4−• and •OH were responsible for the predominant degradation of EEDs. And the removal efficiency of Table 7.6  The mechanism of S2O82− activating by nZVI Equations Fe0 → Fe2+ + 2e− Fe0 + S2O82− → Fe2+ + 2SO42− Fe0 + 2H2O → Fe2+ + H2 + 2OH− S2O82− + Fe2+ → Fe3+ + 2SO42− + SO4−• SO4−• + H2O → SO42− + •OH + H+ Direct way Fe0 + 2S2O82− → Fe2+ + 2SO4−• + 2SO42− Fe0 + S2O82− + 2H2O → Fe2+ + 2SO42− + 2•OH + 2H+ Indirect way

References Hussain et al. (2017), Wang et al. (2017)

Hussain et al. (2017), Wang et al. (2017)

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EEDs was influenced by the dosage of catalyst, initial pH, temperature and the concentration of persulfate significantly (Hussain et  al. 2017; Wang et  al. 2017; Silveira et al. 2017). Moreover, nZVI was also used in the anaerobic digestion of sewage sludge (Suanon et al. 2017). Commercial iron powder (IP, d = 0.2 mm) and nZVI were used as additives to investigate the removal of PPCPs in anaerobic digestion process. The chemical oxygen demand was removed 66.2%, 54.4% and 44.6% in the presence of IP, nZVI and control group, respectively. And chlorinated PPCPs were easier to be removed with nZVI compared to other PPCPs (Suanon et al. 2017).

7.3  Iron Oxide Nanoparticles and Their Composites Sixteen kinds of iron oxides and hydroxides have been known up to now, among which Fe3O4, Fe2O3 containing the structure of α, β, γ and σ are the most widely used materials in the environment remediation (Pouran et  al. 2014). Magnetite (Fe3O4) is special as the pure iron oxide with two kinds of valences Fe (II) and Fe (III). A number of researches about the implications and applications of Fe3O4 nanoparticles (NPs) have been published. Simultaneously having the properties of superparamagnetic and high surface area, Fe3O4 NPs and their composites have been used in cancer monitoring, biomedical/biotechnology, data storage, catalysis, adsorption and others (Revia and Zhang 2016; Wu et al. 2015; Gawande et al. 2013). When used to removal EEDs, Fe3O4 nanoparticles and their composites are mainly acting as an adsorbent and a heterogeneous catalyst.

7.3.1  Fe3O4 Nanoparticles and Their Composites 7.3.1.1  Preparation and Characterization Up to now, the methods for preparing Fe3O4 NPs could be divided into aqueous and non-aqueous routes. Aqueous methods are attractive with their convenience such as co-precipitation, hydrothermal process, sol-gel reactions and polyol, sonolysis or sonochemical method, microwave-assisted synthesis and biosynthesis. Non-­ aqueous approaches often use organic solvent as the medium, such as thermal decomposition and combustion, and microemulsion (Wu et al. 2015). To date, chemical co-precipitation is the most popular method to synthesize Fe3O4 NPs with the advantages of adjustable size, simple facility and high yield, which are shown as Eq. (7.8). The reaction generally undergoes in inert gas and high temperature with a pH value lower than 11. Different types of iron salt (such as sulfates, nitrates and chlorides), the ratio of Fe2+ and Fe3+, the reaction

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temperature and the pH value as well as the other parameters (mechanical stirring rate, dropping rate of alkali solution, reaction time) do having the effect on the properties of Fe3O4 NPs (Wu et  al. 2008). Typically, the synthesized Fe3O4 NPs keep a sizes of 20 ~ 150 nm (Wu et al. 2015). Just as the pristine nZVI, aggregation is also a big problem for Fe3O4 NPs. Thus, several surfactants and functional groups are added into the reaction system before or after the nucleation of Fe3O4 NPs (Wu et al. 2015).

Fe 2   2Fe 3  8OH   Fe  OH 2  2 Fe  OH 3  Fe 3 O 4  4H 2 O (7.8)

The limitations of poor control of particle size and size distribution with chemical co-precipitation promote many new alternative strategies such as thermal decomposition and combustion method (Wu et al. 2015). This nonaqueous method is to inject the precursors in organic solvents such as Fe(CO)5, Fe(N-­ nitrosophenylhydroxylamine)3 and Fe(acetylacetonate)3 into a reaction mixture and reacting under a high temperature generally higher than 200 °C (Wu et al. 2015, 2008). High-quality monodispersed and highly crystalline Fe3O4 NPs could be obtained in this way. Nanoscale size and superparamagnetism allows the Fe3O4 NPs various applications, however they also have the disadvantages of agglomeration and reactivity with oxidizing agents in water (Nosrati et al. 2017). Therefore, surface modification and coating become necessary to improve the stabilization, practicability, variability and versatility of Fe3O4 NPs. Particularly, surface functionalization of Fe3O4 NPs could be classified as in situ surface modification and post-synthesis surface modification (Nosrati et al. 2017). In situ surface modification focuses on the additives of organic small molecules (e.g. -OH, -COOH, -NH2) and polymer (e.g. cellulose and chitosan). During the reaction, these organic small molecules are adsorbed by the NPs through their strong binding after the nucleating of Fe3O4 NPs, while the polymers adsorb the Fe2+/Fe3+ before the nucleating of Fe3O4 NPs (Nosrati et al. 2017; Wu et al. 2015). Post-synthesis surface modification includes two parts: the preparing of Fe3O4 NPs and the modification on the surface of Fe3O4 NPs through coupling agent (Nosrati et al. 2017). The same as nZVI, SEM and TEM are used to learn the size and shape even structural morphology of the Fe3O4 NPs and their composites, and pristine Fe3O4 NPs show as a smooth sphere. The crystalline structure, phase composition as well as atomic arrangement of the nanoparticles are mainly detected by XRD.  X-ray photoelectron spectroscopy (XPS) is also used to confirm the oxidation state and bond energy of the materials. Besides, inductively coupled plasma-atomic emission spectrometry (ICP-AES) is an important technology to confirm the proportion of iron especially for the polymetallic NPs. Fourier transform infrared spectroscopy (FTIR) is used to detect the functional groups that are modified on the surface of Fe3O4 NPs.

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7.3.1.2  Acting as an Adsorbent The separation and enrichment of environmental micro pollutants are necessary and urgent. Fe3O4 NPs have shown their adsorption potential for various organic compounds including EEDs. To date, adsorption of EEDs is mainly focused on two aspects, and one is the improvement of the adsorption capacities and selectivity. This kind of adsorbents are synthesized with suitable size and/or modified with specific functional groups which are summarized in Table 7.7. In this aspect, high specific surface area materials such as graphene, g-C3N4 and biochar are composited with Fe3O4 NPs to achieve a win-win situation. And most of these adsorbents fit Langmuir isotherm model and pseudo second order model well. For example, the β-cyclodextrin capped graphene-Fe3O4 nanocomposite was synthesized for selective adsorption of bisphenol A (BPA), which could be reused 6 times with a decrease of adsorption efficiency low than 10% (Ragavan and Rastogi 2017). And the result also revealed highly selective towards BPA in four kinds of bisphenols. In addition, selective molecularly imprinted polymers (MIPs) are also introduced to Fe3O4 NPs, where Fe3O4 NPs are primary acting as supporting materials and separating tools. Adsorbent such as Fe3O4/ GO@MIP with the advantages of high specific surface area of graphene oxide (GO) and selectivity of MIPs was applied to adsorbing pentachlorophenol (PCP), which showed a high adsorption capacity of about 789.4 mg·g−1 and good selectivity towards PCP in four kinds of chlorophenols. The other research aspect of adsorption is trace detection by modifying the base material with different MIPs and polymers according to EEDs, which can be used as extractant in chromatographic determination. 7.3.1.3  Acting as a Heterogeneous Catalyst/Carrier The Fe3O4-based materials commonly act as a heterogeneous catalyst in Fenton-like process and PMS oxidation process, which are shown in Table 7.8. Being different with nZVI in Fenton-like and PMS oxidation system, the Fe3O4 NPs are more stable and harder to be corroded. In addition, considering the rate constant of Fe2+/H2O2 (Table 7.4), which is much higher than that of Fe3+/H2O2, structural Fe(II) content in the Fe3O4 NPs is much influential in H2O2 oxidation. But Fe3O4 NPs used in photocatalytic system often play a role of supporting and separating which will not be discussed in detail (Kumar et al. 2018; Gao et al. 2017). According to Table 7.8, detailed studies about the degradation of relevant EEDs in the Fenton and PMS system catalyzed by Fe3O4 NPs are not so much. For example, Tan et al. have tried Fe3O4 NPs as the heterogeneous catalyst to activate peroxymonosulfate (PMS) for degrading acetaminophen (APAP). Free radical scavenging tests and electron paramagnetic resonance (EPR) tests have proved the generation of •OH and •SO4−, which explained the great activation ability of Fe3O4 NPs for PMS (Tan et al. 2014). The mechanism of PMS activated by Fe3O4 NPs is shown in Fig. 7.5 (Tan et al. 2014). Different from the low pH value required for Fenton reaction, an APAP (10 mg·L−1) removal efficiency of 75% could be obtained in neutral pH with the Fe3O4 NPs dose of 0.8 g·L−1 and PMS dose of 0.2 mmol·L−1.

Sulfamethoxazole

Triazine

Diazinon

PCP

Diethyl phthalate

Biochar-­Fe3O4

Fe3O4/graphene

Fe3O4/APTES

Fe3O4/GO@MIP

Zeolite/Fe3O4

206.106

789.4

206.18

54.8

13.83

Langmuir

Freundlich

Langmuir

Langmuir

Freundlich

Adsorption capacity (mg·g−1) Adsorption model 59.6 Langmuir

Pseudo first order

Pseudo first order

Pseudo first order

Pseudo first order

PS (low C0) PF (high C0)

Kinetic model Pseudo first order

Farmany et al. (2016)

Boruah et al. (2017)

Reguyal et al. (2017)

References Ragavan and Rastogi (2017)

Pan et al. (2014) High adsorption capacity and good selectivity Mesdaghinia et al. Adsorption (2017) separation and catalytic degradation

Enhanced the adsorption capacity in the presence of some cations. High adsorption capacity

High lights Reused 6 times with a decrease of adsorption efficiency low than 10%. The minimisation and reuse of waste.

BPA Bisphenol A, APTES 3-aminopropyl)triethoxysilane, GO Graphene oxide, MIP Molecularly imprinted polymer, PCP Pentachlorophenol

Pollutants BPA

Materials β-Cyclodextrin capped graphene-Fe3O4

Table 7.7  Summary of the nanoscale Fe3O4 composites for EEDs adsorption

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2 ~ 3.5

3

SMT

DEP

Fe3O4-Mn3O4 NPs/H2O2 Zeolite/Fe3O4/ H2O2 –

3.6 ~ 8.4

–

0 ~ 106

Initial C[oxidant] mmol·L−1 0 ~ 0.5

50

10 ~ 25

10

20

Initial C[target] mg·L−1 2.5 ~ 10

0.2

0.2 ~ 2

10

0 ~ 1.17

Catalyst dosage g·L−1 0 ~ 1.0 Highlights 1) Both •OH and SO4−• played the main role 2) The Fe2+/Fe3+ cycle generates ROS 1) US/Fe3O4/H2O2 system was effective 2) pH range from 3 to 9 It showed a two-stage reduction/oxidation degradation mechanism Mn3O4 enhanced the efficiency of Fenton oxidation The system happened adsorption separation and catalytic degradation

Wan and Wang (2017) Mesdaghinia et al. (2017)

≤ 45% –

Tan et al. (2017)

Huang et al. (2012)

References Tan et al. (2014)

–

≤ 48.5%

TOC removal efficiency ≤ 31%

PMS Peroxymonosulfate, APAP Acetaminophen, US Ultrasonic, BPA Bisphenol A, BDE 209 Polybrominated diphenyl ethers, SMT Sulfamethazine, DEP Diethyl phthalate

7.1

BDE 209

nZVI@ Fe3O4 NPs/H2O2/US

3 ~ 10

BPA

Initial pH 3 ~ 11

Fe3O4 NPs/ H2O2/US

Materials Fe3O4 NPs/ PMS

Chemical Pollutants structure APAP

Table 7.8  The degradation of EEDs in the H2O2 or PMS systems catalyzed by Fe3O4 NPs and their composites

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Fig. 7.5  The mechanism of PMS activated by Fe3O4 NPs

7.3.2  Fe2O3 Nanoparticles and their Composites Fe2O3 has the structure of hematite (α-Fe2O3), β-Fe2O3, maghemite (γ-Fe2O3) and σ-Fe2O3, while α-Fe2O3 and γ-Fe2O3 could occur in nature and the other two Fe2O3 are prepared in laboratory. Generally, with the advantages of high corrosion resistance, abundance, nontoxicity and low processing costs under ambient conditions, α-Fe2O3 and γ-Fe2O3 are commonly used as gas sensors, high capacity electrodes, photocatalysts, pigments and so on (Mirzaei et al. 2016; Tao et al. 2013). 7.3.2.1  Preparation and Characterization The preparation of α-Fe2O3 NPs and γ-Fe2O3 NPs are similarly with that of Fe3O4 NPs. In detail, the γ-Fe2O3 NPs are often synthesized by a direct mineralization of Fe3+ and an adjusted oxidation of Fe3O4, while α-Fe2O3 NPs are mainly prepared through hydrothermal process (Wu et al. 2015). The characterization of Fe2O3 NPs is commonly the same as nZVI and Fe3O4 NPs. 7.3.2.2  Acting as a Heterogeneous Photocatalyst With the magnetism similar to Fe3O4, γ-Fe2O3 could also be applied in selective adsorption and magnetic separation (Janoš et  al. 2015). However, an interesting application of α-Fe2O3 and γ-Fe2O3 is the photocatalyst in visible light. As it’s known, heterojunctions with excellent photocatalytic activity should satisfy two important conditions, one of which is the selected materials could form the well-structured interfaces easily, and the other is that the band structure of the catalysts should match well with each other (Wei et  al. 2014). Considering the band gaps of α-Fe2O3 and γ-Fe2O3 (2.2 and 2.3 eV, respectively), researches has shown that these n-type semiconductors are suitable for photocatalysis as shown in Fig. 7.6 (Wu et al. 2015; Wei et al. 2014). The redox potentials (EH) for H2O/•OH, 1O2/O2 (1O2 is singlet oxygen), 1O2/O2−• are 2.2 eV, 1.88 eV and 0.97 eV in aqueous media,

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Fig. 7.6  The photocatalytic activity of Fe2O3 in theoretically

respectively (Zhao et al. 2017). With the conduction band of 0.46 eV and valence band of 2.66 eV of Fe2O3, this iron oxide has sufficient energy to generate ROS like •OH and O2−• in water when used in photocatalysis. Thus, Wei et  al. proved the phenomenon that α-Fe2O3/γ-Fe2O3 could enhance the visible light photocatalytic activity (Wei et al. 2014). Zhao et al. had synthesized three kinds of metal oxide-SiO2 nanocomposites such as CuO-SiO2, Fe2O3-SiO2 and ZnO-SiO2 in order to photodegrade BPA with the band gaps of 1.70 eV, 2.20 eV and 3.20 eV respectively (Zhao et al. 2017). EPR signals showed the result that CuO-SiO2 system generated more •OH and electrons than Fe2O3-SiO2 and ZnO-SiO2 with the lowest band gap to get more energy under the same irradiation. Thus, CuO-SiO2 system showed the highest removal efficiency of BPA followed by Fe2O3-SiO2 then ZnO-SiO2 (Zhao et al. 2017). Overall, although the photodegradation of BPA by Fe2O3-SiO2 did not serve the highest removal efficiency, it proved the potential photocatalytic ability of Fe2O3. The similar experiment by Mirmasoomi et al. studied the degradation of diazinon under visible light catalyzed by TiO2/γ-Fe2O3 nanocomposite (Mirmasoomi et al. 2017). An obvious adsorption in the visible range had been realized with the doping of γ-Fe2O3, and the degradation efficiency of 88.93% was comparable under 0.1 g·L−1 TiO2/γ-Fe2O3, 10 mg·L−1 diazinon, 14 W/cm2 visible light intensity and 45 min reaction time (Mirmasoomi et al. 2017).

7.4  Other Novel Fe-Based Nanomaterials Besides the commonly used Fe-based nanomaterials such as nZVI and iron oxide NPs, some novel materials are continuing without end, such as FeOOH NPs, MOF, bimetallic NPs, CuFe2O4 and so on.

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Fig. 7.7  The two ways to generate •OH in ozone oxidation catalyzed by FeOOH

Goethite (FeOOH) has been reported to be readily hydroxylated in water. These surface hydroxyl groups are the active sites to enhance the generation of •OH in aqueous ozone, while the catalytic activity of ɑ-FeOOH is highest than that of β-FeOOH and γ-FeOOH, according to Fig. 7.7 (Zhang et al. 2008). Thus, Yang et al. synthesized the β-FeOOH/Al2O3 nanocomposite for the degradation of ibuprofen (IBU) and ciprofloxacin (CPFX) with ozone (Zhang et al. 2008). Research proved that the Lewis acid sites on the surface of β-FeOOH/Al2O3 have a strong interaction with O3 to generate ROS which was better than β-FeOOH or Al2O3 alone. And the mineralization rates of IBU (10 mg·L−1) and CPFX (10 mg·L−1) were 90% and 88% under the condition of pH 7, catalyst dosage of 1.5 g·L−1, 30 mg·L−1 O3 with the flow rate of 12 L·h−1 compared to that of 20% and 30% without catalyst, respectively (Zhang et al. 2008). MOFs are widely used in adsorption and heterogeneous catalysis in AOPs with the properties of crystalline structures and high specific surface area. And Fe-based MOFs have exhibited excellent performance for the degradation of organic compounds in Fenton and PMS oxidation (Sharma and Feng 2017). New researches have focused on the nanomaterials synthesized from further processing of MOF (Fe) (Chen et al. 2017; Zeng et al. 2017). For example, Chen et al. synthesized the magnetic Fe-Cx nanocomposites through the pyrolysis of Fe-MOF in different temperatures (400 ~ 600 °C) and applied the materials to Fenton-like reaction for the removal of 4-nitrophenol (4-NP). The result showed a removal efficiency of about 90% in unadjusted pH similarly to that of pH 2.24 and 4.08 (Chen et al. 2017). In addition, the Fe/Fe3C NPs with N-doped porous carbon (NC) by the pyrolysis of Fe-MIL-88B-NH2 MOF was prepared to degrade 4-chlorophenol (4-CP) in PMS oxidation process (Zeng et al. 2017). H2O2 was used to compare with PMS oxidation under the same Fe/Fe3C@CN catalytic conditions, which showed only about a half removal efficiency of that by PMS oxidation (Zeng et al. 2017). The high oxidation ability of PMS may be related to its unsymmetrical structure.

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Fe-based bimetallic nanomaterials such as Fe/Pd, Fe/Pt, Fe/Cu, Fe/Ni and Fe3O4-­ Mn3O4 NPs are other interesting materials (Dong et al. 2018; Li et al. 2017; Wan and Wang 2017; Chang et al. 2011). Our previous work had synthesized nZVI with different sizes of Ni0 (30, 50, 80 and 100 nm) for the reductive dechlorination of pentachloropheno (PCP) (Cheng et  al. 2010). The Fe/Ni bimetallic NPs showed an increasingly enhanced dechlorination effect compared to that of nZVI with the decreasing size of Ni0. And Ni NPs acted as catalyst for the degradation of PCP in the reaction (Cheng et al. 2010). Besides, the other researches on the debromination of TBA and TBBPA by Fe/Ni NPs, and the degradation of tetracycline by Fe/Ni NPs further studied the role of Ni0 loading on the surface of nZVI, which could be concluded as Eq. (7.9) and (7.10) (Dong et al. 2018; Li et al. 2017; Chang et al. 2011). Ni



H 2  2H



2H   2e   2H

Ni

(7.9) (7.10)

7.5  Conclusions The application of Fe-based nanomaterials in the removal of EEDs by various physical and chemical ways could effectively reduce the potential toxicity of EEDs for people. As research demonstrates, pristine nZVI and its composites are mainly used to reduce polyhalogenated aromatic hydrocarbons and nitroaromatics based on the generation of active hydrogen. Agglomeration and corrosion are the main limitations for the further and broader application of nZVI. Thus, stabilized and functionalized nZVI have been synthesized for the heterogeneous catalysis in AOPs processes, which has greatly broadened the field of degradable pollutants. These nanosized nZVI composites not only enhance the removal efficiencies of EEDs in AOPs system by accelerating the generation of ROS, but also expand the suitable pH range of catalyzing H2O2. With the properties of nanoscale size and superparamagnetism, Fe3O4 NPs and their functionalized composites are mainly used as adsorbents and heterogeneous catalysts in Fenton and PMS oxidation. One aim of these adsorbents is the improvement of the adsorption capacities toward various EEDs by loading functional materials to achieve a win-win situation. And the other one is the enhancement of selectivity towards relevant EEDs for trace detection under ambient condition, where Fe3O4 NPs are mainly used as supporting materials and separating tools. The researches of Fe3O4 NPs in heterogeneous catalysis for EEDs by H2O2 and PMS are not so much as those of nZVI. Probably reason is related to the lower reactive activity with oxidant. Fe2O3 NPs are newly applied into photocatalysis for EEDs. These nanomaterials have shown an optimistic prospect in visible light photocatalytic with the studies of α-Fe2O3/γ-Fe2O3 NPs. Other novel Fe-based nanomaterials such as FeOOH are

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found to have excellent catalytic activity in O3 oxidation. And Fe-based bimetallic nanomaterials could enhance the reaction activities of nZVI for dehalogenation and denitration obviously. The use of Fe-based nanomaterials in the removal of EEDs is extensive and deserved further investigation. However, the potential threats brought by the application of these nanomaterials especially by the nZVI and its composites also deserve to be more recognized. Acknowledgements  This work was supported by the National Natural Science Foundation of China (Grant No. 51778618), which is greatly acknowledged.

References Ahmed MB, Zhou JL, Ngo HH, Guo W, Thomaidis NS, Xu J (2017) Progress in the biological and chemical treatment technologies for emerging contaminant removal from wastewater: a critical review. J Hazard Mater 323:274–298. https://doi.org/10.1016/j.jhazmat.2016.04.045 Bastami TR, Entezari MH (2012) Activated carbon from carrot dross combined with magnetite nanoparticles for the efficient removal of p-nitrophenol from aqueous solution. Chem Eng J 210:510–519. https://doi.org/10.1016/j.cej.2012.08.011 Bhattachatjee S, Basnet M, Tufenkji N, Ghoshal S (2016) Effects of Rhamnolipid and Carboxymethylcellulose coatings on reactivity of palladium-doped nanoscale Zerovalent Iron particles. Environ Sci Technol 50(4):1812–1820. https://doi.org/10.1021/acs.est.5b05074 Bokare AD, Choi W (2014) Review of iron-free Fenton-like systems for activating H2O2 in advanced oxidation processes. J Hazard Mater 275:121–135. https://doi.org/10.1016/j. jhazmat.2014.04.054 Bolong N, Ismail AF, Salim MR, Matsuura T (2009) A review of the effects of emerging contaminants in wastewater and options for their removal. Desalination 239(1–3):229–246. https://doi. org/10.1016/j.desal.2008.03.020 Boruah PK, Sharma B, Hussain N, Das MR (2017) Magnetically recoverable Fe3O4/graphene nanocomposite towards efficient removal of triazine pesticides from aqueous solution: investigation of the adsorption phenomenon and specific ion effect. Chemosphere 168:1058–1067. https://doi.org/10.1016/j.chemosphere.2016.10.103 Brewster JH (1954) Mechanisms of reductions at metal surfaces. I. A general working hypothesis. J Am Chem Soc 76(24):6361–6363. https://doi.org/10.1021/ja01653a034 Bystrzejewski M (2011) Synthesis of carbon-encapsulated iron nanoparticles via solid state reduction of iron oxide nanoparticles. J Solid State Chem 184(6):1492–1498. https://doi. org/10.1016/j.jssc.2011.04.018 Chang H, Choo K, Lee B, Choi S (2009) The methods of identification, analysis, and removal of endocrine disrupting compounds (EDCs) in water. J Hazard Mater 172(1):1–12. https://doi. org/10.1016/j.jhazmat.2009.06.135 Chang C, Lian F, Zhu L (2011) Simultaneous adsorption and degradation of gamma-HCH by nZVI/ Cu bimetallic nanoparticles with activated carbon support. Environ Pollut 159(10):2507–2514. https://doi.org/10.1016/j.envpol.2011.06.021 Chen SS, Hsu HD, Li CW (2004) A new method to produce nanoscale iron for nitrate removal. J Nanopart Res 6(6):639–647. https://doi.org/10.1007/s11051-­004-­6672-­2 Chen H, Luo H, Lan Y, Dong T, Hu B, Wang Y (2011) Removal of tetracycline from aqueous solutions using polyvinylpyrrolidone (PVP-K30) modified nanoscale zero valent iron. J Hazard Mater. https://doi.org/10.1016/j.jhazmat.2011.04.089 Chen J, Qiu X, Fang Z, Yang M, Pokeung T, Gu F, Cheng W, Lan B (2012) Removal mechanism of antibiotic metronidazole from aquatic solutions by using nanoscale zero-valent iron particles. Chem Eng J 181:113–119. https://doi.org/10.1016/j.cej.2011.11.037

286

R. Cheng et al.

Chen H, Cao Y, Wei E, Gong T, Xian Q (2016) Facile synthesis of graphene nano zero-valent iron composites and their efficient removal of trichloronitromethane from drinking water. Chemosphere 146:32–39. https://doi.org/10.1016/j.chemosphere.2015.11.095 Chen D, Chen S, Jiang Y, Xie S, Quan H, Hua L, Luo X, Guo L (2017) Heterogeneous Fentonlike catalysis of Fe-MOF derived magnetic carbon nanocomposites for degradation of 4-­nitrophenol. RSC Adv 7(77):49024–49030. https://doi.org/10.1039/c7ra09234b Cheng R, Zhou W, Wang J, Qi D, Guo L, Zhang W, Qian Y (2010) Dechlorination of pentachlorophenol using nanoscale Fe/Ni particles: role of nano-Ni and its size effect. J Hazard Mater 180(1–3):79–85. https://doi.org/10.1016/j.jhazmat.2010.03.068 Cheng R, Cheng C, Liu G, Zheng X, Li G, Li J (2015) Removing pentachlorophenol from water using a nanoscale zero-valent iron/H2O2 system. Chemosphere 141:138–143. https://doi. org/10.1016/j.chemosphere.2015.06.087 Crane RA, Scott TB (2012) Nanoscale zero-valent iron: future prospects for an emerging water treatment technology. J Hazard Mater 211-212:112–125. https://doi.org/10.1016/j. jhazmat.2011.11.073 Daneshkhah M, Hossaini H, Malakootian M (2017) Removal of metoprolol from water by sepiolite-­supported nanoscale zero-valent iron. J Environ Chem Eng 5(4):3490–3499. https:// doi.org/10.1016/j.jece.2017.06.040 Derco J, Dudáš J, Valičková M, Šimovičová K, Kecskés J (2015) Removal of micropollutants by ozone based processes. Chem Eng Process Process Intensif 94:78–84. https://doi.org/10.1016/j. cep.2015.03.014 Diamanti-Kandarakis E, Bourguignon J, Giudice LC, Hauser R, Prins GS, Soto AM, Zoeller RT, Gore AC (2009) Endocrine-disrupting chemicals: an Endocrine Society scientific statement. Endocr Rev 30(4):293–342. https://doi.org/10.1210/er.2009-­0002 Dong H, Jiang Z, Zhang C, Deng J, Hou K (2018) Removal of tetracycline by Fe/Ni bimetallic nanoparticles in aqueous solution. J Colloid Interface Sci 513:117–125. https://doi. org/10.1016/j.jcis.2017.11.021 Dror I, Jacov OM, Cortis A, Berkowitz B (2012) Catalytic transformation of persistent contaminants using a new composite material based on Nanosized zero-valent Iron. ACS Appl Mater Interface 4(7):3416–3423. https://doi.org/10.1021/am300402q Fang Z, Chen J, Qiu X, Qiu X, Cheng W, Zhu L (2011) Effective removal of antibiotic metronidazole from water by nanoscale zero-valent iron particles. Desalination 268(1–3):60–67. https:// doi.org/10.1016/j.desal.2010.09.051 Farmany A, Mortazavi SS, Mahdavi H (2016) Ultrasond-assisted synthesis of Fe3O4/SiO2 core/ shell with enhanced adsorption capacity for diazinon removal. J Magn Magn Mater 416:75–80. https://doi.org/10.1016/j.jmmm.2016.04.007 Fu Y, Peng L, Zeng Q, Yang Y, Song H, Shao J, Liu S, Gu J (2015) High efficient removal of tetracycline from solution by degradation and flocculation with nanoscale zerovalent iron. Chem Eng J 270:631–640. https://doi.org/10.1016/j.cej.2015.02.070 Fu R, Xu Z, Peng L, Bi D (2016) Removal of polybrominated diphenyl ethers by biomass carbon-­ supported nanoscale zerovalent iron particles: influencing factors, kinetics, and mechanism. Environ Sci Pollut Res 23(23):23983–23993. https://doi.org/10.1007/s11356-­016-­7621-­1 Gao S, Guo C, Hou S, Wan L, Wang Q, Lv J, Zhang Y, Gao J, Meng W, Xu J (2017) Photocatalytic removal of tetrabromobisphenol A by magnetically separable flower-like BiOBr/BiOI/Fe3O4 hybrid nanocomposites under visible-light irradiation. J Hazard Mater 331:1–12. https://doi. org/10.1016/j.jhazmat.2017.02.030 Garrido-Ramirez EG, Theng BKG, Mora ML (2010) Clays and oxide minerals as catalysts and nanocatalysts in Fenton-like reactions - a review. Appl Clay Sci 47(3–4):182–192. https://doi. org/10.1016/j.clay.2009.11.044 Gawande MB, Branco PS, Varma RS (2013) Nano-magnetite (Fe3O4) as a support for recyclable catalysts in the development of sustainable methodologies. Chem Soc Rev 42(8):3371–3393. https://doi.org/10.1039/c3cs35480f

7  Fe-Based Nanomaterials for Removing the Environmental Endocrine Disrupting…

287

Ghauch A, Tuqan A, Assia HA (2009) Antibiotic removal from water: elimination of amoxicillin and ampicillin by microscale and nanoscale iron particles. Environ Pollut 157(5):1626–1635. https://doi.org/10.1016/j.envpol.2008.12.024 Gore AC, Chappell VA, Fenton SE, Flaws JA, Nadal A, Prins GS, Toppari J, Zoeller RT (2015) EDC-2: the Endocrine Society's second scientific statement on endocrine-disrupting chemicals. Endocr Rev 36(6):E1–E150. https://doi.org/10.1210/er.2015-­1010 Guo Y, Huang W, Chen B, Zhao Y, Liu D, Sun Y, Gong B (2017) Removal of tetracycline from aqueous solution by MCM-41-zeolite A loaded nano zero valent iron: synthesis, characteristic, adsorption performance and mechanism. J Hazard Mater 339:22–32. https://doi.org/10.1016/j. jhazmat.2017.06.006 Han Y, Shi N, Wang H, Pan X, Fang H, Yu Y (2016) Nanoscale zerovalent iron-mediated degradation of DDT in soil. Environ Sci Pollut Res 23(7):6253–6263. https://doi.org/10.1007/ s11356-­015-­5850-­3 He J, Yang X, Men B, Wang D (2016) Interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials: a review. J Environ Sci 39:97–109. https://doi.org/10.1016/j. jes.2015.12.003 Hoag GE, Collins JB, Holcomb JL, Hoag JR, Nadagouda MN, Varma RS (2009) Degradation of bromothymol blue by ‘greener’ nano-scale zero-valent iron synthesized using tea polyphenols. J Mater Chem 19(45):8671. https://doi.org/10.1039/b909148c Hoch LB, Mack EJ, Hydutsky BW, Hershman JM, Skluzacek JM, Mallouk TE (2008) Carbothermal synthesis of carbon-supported nanoscale zero-valent Iron particles for the remediation of hexavalent chromium. Environ Sci Technol 42(7):2600–2605. https://doi.org/10.1021/ es702589u Huang C, Hsieh W, Pan J, Chang S (2007) Characteristic of an innovative TiO2/Fe0 composite for treatment of azo dye. Sep Purif Technol 58(1):152–158. https://doi.org/10.1016/j. seppur.2007.07.034 Huang R, Fang Z, Yan X, Cheng W (2012) Heterogeneous sono-Fenton catalytic degradation of bisphenol a by Fe3O4 magnetic nanoparticles under neutral condition. Chem Eng J 197:242–249. https://doi.org/10.1016/j.cej.2012.05.035 Hussain I, Li M, Zhang Y, Li Y, Huang S, Du X, Liu G, Hayat W, Anwar N (2017) Insights into the mechanism of persulfate activation with nZVI/BC nanocomposite for the degradation of nonylphenol. Chem Eng J 311:163–172. https://doi.org/10.1016/j.cej.2016.11.085 Hwang Y, Kim D, Shin H (2011) Effects of synthesis conditions on the characteristics and reactivity of nano scale zero valent iron. Appl Catal B Environ 105(1–2):144–150. https://doi. org/10.1016/j.apcatb.2011.04.005 Janoš P, Kuráň P, Pilařová V, Trögl J, Šťastný M, Pelant O, Henych J, Bakardjieva S, Životský O, Kormunda M, Mazanec K, Skoumal M (2015) Magnetically separable reactive sorbent based on the CeO2/γ-Fe2O3 composite and its utilization for rapid degradation of the organophosphate pesticide parathion methyl and certain nerve agents. Chem Eng J 262:747–755. https://doi. org/10.1016/j.cej.2014.10.016 Jarosova B, Filip J, Hilscherova K, Tucek J, Simek Z, Giesy JP, Zboril R, Blaha L (2015) Can zero-valent iron nanoparticles remove waterborne estrogens? J Environ Manag 150:387–392. https://doi.org/10.1016/j.jenvman.2014.12.007 Joss A, Keller E, Alder AC, Gobel A, McArdell CS, Ternes T, Siegrist H (2005) Removal of pharmaceuticals and fragrances in biological wastewater treatment. Water Res 39(14):3139–3152. https://doi.org/10.1016/j.watres.2005.05.031 Karim S, Bae S, Greenwood D, Hanna K, Singhal N (2017) Degradation of 17α-ethinylestradiol by nano zero valent iron under different pH and dissolved oxygen levels. Water Res 125:32–41. https://doi.org/10.1016/j.watres.2017.08.029 Kimura K, Toshima S, Amy G, Watanabe Y (2004) Rejection of neutral endocrine disrupting compounds (EDCs) and pharmaceutical active compounds (PhACs) by RO membranes. J Membr Sci 245(1–2):71–78. https://doi.org/10.1016/j.memsci.2004.07.018

288

R. Cheng et al.

Kong LB, Zhang TS, Ma J, Boey F (2008) Progress in synthesis of ferroelectric ceramic materials via high-energy mechanochemical technique. Prog Mater Sci 53(2):207–322. https://doi. org/10.1016/j.pmatsci.2007.05.001 Kumar A, Kumar A, Sharma G, Al-Muhtaseb AH, Naushad M, Ghfar AA, Stadler FJ (2018) Quaternary magnetic BiOCl/g-C3N4/Cu2O/Fe3O4 nano-junction for visible light and solar powered degradation of sulfamethoxazole from aqueous environment. Chem Eng J 334:462–478. https://doi.org/10.1016/j.cej.2017.10.049 Lee SD, Mallampati SR, Lee BH (2017) Enhanced removal of ethanolamine from secondary system of nuclear power plant wastewater by novel hybrid nano zero-valent iron and pressurized ozone initiated oxidation process. Environ Sci Pollut Res 24(21):17769–17778. https://doi. org/10.1007/s11356-­017-­9416-­4 Lefevre E, Bossa N, Wiesner MR, Gunsch CK (2016) A review of the environmental implications of in situ remediation by nanoscale zero valent iron (nZVI): behavior, transport and impacts on microbial communities. Sci Total Environ 565:889–901. https://doi.org/10.1016/j. scitotenv.2016.02.003 Li S, Yan W, Zhang W (2009) Solvent-free production of nanoscale zero-valent iron (nZVI) with precision milling. Green Chem 11(10):1618. https://doi.org/10.1039/b913056j Li S, Elliott DW, Spear ST, Ma L, Zhang W (2011a) Hexachlorocyclohexanes in the environment: mechanisms of Dechlorination. Crit Rev Environ Sci Technol 41(19):1747–1792. https://doi. org/10.1080/10643389.2010.481592 Li Y, Zhang Y, Li J, Zheng X (2011b) Enhanced removal of pentachlorophenol by a novel composite: nanoscale zero valent iron immobilized on organobentonite. Environ Pollut 159(12):3744–3749. https://doi.org/10.1016/j.envpol.2011.07.016 Li S, Xu M, Wu X, Luo J (2016) Synergetic recognition and separation of kelthane and pyridaben base on magnetic molecularly imprinted polymer nanospheres. J Sep Sci 39(20):4019–4026. https://doi.org/10.1002/jssc.201600699 Li Y, Li X, Han D, Huang W, Yang C (2017) New insights into the role of Ni loading on the surface structure and the reactivity of nZVI toward tetrabromo- and tetrachlorobisphenol A. Chem Eng J 311:173–182. https://doi.org/10.1016/j.cej.2016.11.084 Lin Y, Tseng H, Wey M, Lin M (2010) Characteristics of two types of stabilized nano zero-­ valent iron and transport in porous media. Sci Total Environ 408(10):2260–2267. https://doi. org/10.1016/j.scitotenv.2010.01.039 Liu A, Zhang WX (2014) Fine structural features of nanoscale zero-valent iron characterized by spherical aberration corrected scanning transmission electron microscopy (Cs-STEM). Analyst 139(18):4512–4518. https://doi.org/10.1039/c4an00679h Liu Z, Kanjo Y, Mizutani S (2009) Removal mechanisms for endocrine disrupting compounds (EDCs) in wastewater treatment  - physical means, biodegradation, and chemical advanced oxidation: a review. Sci Total Environ 407(2):731–748. https://doi.org/10.1016/j. scitotenv.2008.08.039 Liu G, Yang X, Li T, She Y, Wang S, Wang J, Zhang M, Jin F, Jin M, Shao H, Shi M (2015) Preparation of a magnetic molecularly imprinted polymer using g-C3N4–Fe3O4 for atrazine adsorption. Mater Lett 160:472–475. https://doi.org/10.1016/j.matlet.2015.07.157 Liu W, Ma J, Shen C, Wen Y, Liu W (2016) A pH-responsive and magnetically separable dynamic system for efficient removal of highly dilute antibiotics in water. Water Res 90:24–33. https:// doi.org/10.1016/j.watres.2015.12.025 Liu G, Li L, Xu D, Huang X, Xu X, Zheng S, Zhang Y, Lin H (2017a) Metal-organic framework preparation using magnetic graphene oxide–β-cyclodextrin for neonicotinoid pesticide adsorption and removal. Carbohydr Polym 175:584–591. https://doi.org/10.1016/j. carbpol.2017.06.074 Liu A, Liu J, Han J, Zhang W (2017b) Evolution of nanoscale zero-valent iron (nZVI) in water: microscopic and spectroscopic evidence on the formation of nano- and micro-structured iron oxides. J Hazard Mater 322:129–135. https://doi.org/10.1016/j.jhazmat.2015.12.070

7  Fe-Based Nanomaterials for Removing the Environmental Endocrine Disrupting…

289

Ma L, Rathnayake SI, He H, Zhu R, Zhu J, Ayoko GA, Li J, Xi Y (2016) In situ sequentially generation of acid and ferrous ions for environmental remediation. Chem Eng J 302:223–232. https://doi.org/10.1016/j.cej.2016.05.065 Ma Q, Zhang H, Deng X, Cui Y, Cheng X, Li X, Xie M, Cheng Q, Li B (2017) Electrochemical fabrication of NZVI/TiO2 nano-tube arrays photoelectrode and its enhanced visible light photocatalytic performance and mechanism for degradation of 4-chlorphenol. Sep Purif Technol 182:144–150. https://doi.org/10.1016/j.seppur.2017.03.047 Matheson LJ, Tratnyek PG (1994) Reductive dehalogenation of chlorinated methanes by iron metal. Environ Sci Technol 28(12):2045–2053. https://doi.org/10.1021/es00061a012 Mesdaghinia A, Azari A, Nodehi RN, Yaghmaeian K, Bharti AK, Agarwal S, Gupta VK, Sharafi K (2017) Removal of phthalate esters (PAEs) by zeolite/Fe3O4: investigation on the magnetic adsorption separation, catalytic degradation and toxicity bioassay. J Mol Liq 233:378–390. https://doi.org/10.1016/j.molliq.2017.02.094 Mirmasoomi SR, Mehdipour Ghazi M, Galedari M (2017) Photocatalytic degradation of diazinon under visible light using TiO2/Fe2O3 nanocomposite synthesized by ultrasonic-assisted impregnation method. Sep Purif Technol 175:418–427. https://doi.org/10.1016/j.seppur.2016.11.021 Mirzaei A, Hashemi B, Janghorban K (2016) α-Fe2O3 based nanomaterials as gas sensors. J Mater Sci Mater Electron 27(4):3109–3144. https://doi.org/10.1007/s10854-­015-­4200-­z Mueller NC, Braun J, Bruns J, Cernik M, Rissing P, Rickerby D, Nowack B (2012) Application of nanoscale zero valent iron (NZVI) for groundwater remediation in Europe. Environ Sci Pollut Res 19(2):550–558. https://doi.org/10.1007/s11356-­011-­0576-­3 Munoz M, de Pedro ZM, Casas JA, Rodriguez JJ (2015) Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation  – a review. Appl Catal B Environ 176-177:249–265. https://doi.org/10.1016/j.apcatb.2015.04.003 Mylon SE, Sun Q, Waite TD (2010) Process optimization in use of zero valent iron nanoparticles for oxidative transformations. Chemosphere 81(1):127–131. https://doi.org/10.1016/j. chemosphere.2010.06.045 Nosrati H, Salehiabar M, Davaran S, Ramazani A, Manjili HK, Danafar H (2017) New advances strategies for surface functionalization of iron oxide magnetic nano particles (IONPs). Res Chem Intermed 43(12):7423–7442. https://doi.org/10.1007/s11164-­017-­3084-­3 Nurmi JT, Tratnyek PG, Sarathy V, Baer DR, Amonette JE, Pecher K, Wang C, Linehan JC, Matson DW, Penn RL, Driessen MD (2005) Characterization and properties of metallic Iron nanoparticles: spectroscopy, electrochemistry, and kinetics. Environ Sci Technol 39(5):1221–1230. https://doi.org/10.1021/es049190u Pan S, Shen H, Zhou L, Chen X, Zhao Y, Cai M, Jin M (2014) Controlled synthesis of pentachlorophenol-­imprinted polymers on the surface of magnetic graphene oxide for highly selective adsorption. J Mater Chem A 2(37):15345–15356. https://doi.org/10.1039/c4ta02600d Pouran SR, Raman AAA, Daud WMAW (2014) Review on the application of modified iron oxides as heterogeneous catalysts in Fenton reactions. J Clean Prod 64:24–35. https://doi. org/10.1016/j.jclepro.2013.09.013 Qiang Y, Antony J, Sharma A, Nutting J, Sikes D, Meyer D (2006) Iron/iron oxide core-shell nanoclusters for biomedical applications. J Nanopart Res 8(3–4):489–496. https://doi.org/10.1007/ s11051-­005-­9011-­3 Ragavan KV, Rastogi NK (2017) β-Cyclodextrin capped graphene-magnetite nanocomposite for selective adsorption of Bisphenol-A. Carbohydr Polym 168:29–137. https://doi.org/10.1016/j. carbpol.2017.03.045 Ramos MAV, Yan W, Li X, Koel BE, Zhang W (2009) Simultaneous oxidation and reduction of arsenic by zero-valent Iron nanoparticles: understanding the significance of the core−shell structure. J Phys Chem C 113(33):14591–14594. https://doi.org/10.1021/jp9051837 Reguyal F, Sarmah AK, Gao W (2017) Synthesis of magnetic biochar from pine sawdust via oxidative hydrolysis of FeCl2 for the removal sulfamethoxazole from aqueous solution. J Hazard Mater 321:868–878. https://doi.org/10.1016/j.jhazmat.2016.10.006

290

R. Cheng et al.

Revia RA, Zhang M (2016) Magnetite nanoparticles for cancer diagnosis, treatment, and treatment monitoring: recent advances. Mater Today 19(3):157–168. https://doi.org/10.1016/j. mattod.2015.08.022 Ruhí A, Acuña V, Barceló D, Huerta B, Mor J, Rodríguez-Mozaz S, Sabater S (2016) Bioaccumulation and trophic magnification of pharmaceuticals and endocrine disruptors in a Mediterranean river food web. Sci Total Environ 540:250–259. https://doi.org/10.1016/j. scitotenv.2015.06.009 San Roman I, Alonso ML, Bartolome L, Galdames A, Goiti E, Ocejo M, Moragues M, Alonso RM, Vilas JL (2013) Relevance study of bare and coated zero valent iron nanoparticles for lindane degradation from its by-product monitorization. Chemosphere 93(7):1324–1332. https://doi. org/10.1016/j.chemosphere.2013.07.050 Schrick B, Hydutsky BW, Blough JL, Mallouk TE (2004) Delivery vehicles for zerovalent metal nanoparticles in soil and groundwater. Chem Mater 16(11):2187–2193. https://doi.org/10.1021/ cm0218108 Sharma VK, Feng M (2017) Water depollution using metal-organic frameworks-catalyzed advanced oxidation processes: a review. J Hazard Mater. https://doi.org/10.1016/j. jhazmat.2017.09.043 Shih Y, Hsu C, Su Y (2011) Reduction of hexachlorobenzene by nanoscale zero-valent iron: kinetics, pH effect, and degradation mechanism. Sep Purif Technol 76(3):268–274. https://doi. org/10.1016/j.seppur.2010.10.015 Shirazi E, Torabian A, Nabi-Bidhendi G (2013) Carbamazepine removal from groundwater: effectiveness of the TiO2/UV, Nanoparticulate zero-valent Iron, and Fenton (NZVI/H2O2) processes. Clean Soil Air Water 41(11):1062–1072. https://doi.org/10.1002/clen.201200222 Silveira JE, Barreto-Rodrigues M, Cardoso TO, Pliego G, Munoz M, Zazo JA, Casas JA (2017) Nanoscale Fe/Ag particles activated persulfate: optimization using response surface methodology. Water Sci Technol 75(9):2216–2224. https://doi.org/10.2166/wst.2017.063 Singh SP, Bose P (2016) Degradation kinetics of Endosulfan isomers by micron- and nano-sized zero valent iron particles (MZVI and NZVI). J Chem Technol Biotechnol 91(8):2313–2321. https://doi.org/10.1002/jctb.4818 Singh SP, Bose P (2017) Reductive dechlorination of endosulfan isomers and its metabolites by zero-­ valent metals: reaction mechanism and degradation products. RSC Adv 7(44):27668–27677. https://doi.org/10.1039/C7RA02430D Snyder SA, Westerhoff P, Yoon Y, Sedlak DL (2003) Pharmaceuticals, personal care products, and endocrine disruptors in water: implications for the water industry. Environ Eng Sci 20(5):449–469. https://doi.org/10.1089/109287503768335931 Stumm-Zollinger E, Fair GM (1965) Biodegradation of steroid hormones. J Water Pollut Control Fed 37(11):1506–1510 Suanon F, Sun Q, Li M, Cai X, Zhang Y, Yan Y, Yu C (2017) Application of nanoscale zero valent iron and iron powder during sludge anaerobic digestion: impact on methane yield and pharmaceutical and personal care products degradation. J Hazard Mater 321:47–53. https://doi. org/10.1016/j.jhazmat.2016.08.076 Sun Z, Zheng S, Ayoko GA, Frost RL, Xi Y (2013) Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials. J Hazard Mater 263:768–777. https://doi.org/10.1016/j.jhazmat.2013.10.045 Tan C, Gao N, Deng Y, Deng J, Zhou S, Li J, Xin X (2014) Radical induced degradation of acetaminophen with Fe3O4 magnetic nanoparticles as heterogeneous activator of peroxymonosulfate. J Hazard Mater 276:452–460. https://doi.org/10.1016/j.jhazmat.2014.05.068 Tan L, Lu S, Fang Z, Cheng W, Tsang EP (2017) Enhanced reductive debromination and subsequent oxidative ring-opening of decabromodiphenyl ether by integrated catalyst of nZVI supported on magnetic Fe3O4 nanoparticles. Appl Catal B Environ 200:200–210. https://doi. org/10.1016/j.apcatb.2016.07.005 Tao Y, Gao Q, Di J, Wu X (2013) Gas sensors based on α-Fe2O3 Nanorods, nanotubes and nanocubes. J Nanosci Nanotechnol 13(8):5654–5660. https://doi.org/10.1166/jnn.2013.7559

7  Fe-Based Nanomaterials for Removing the Environmental Endocrine Disrupting…

291

Wan Z, Wang J (2017) Degradation of sulfamethazine antibiotics using Fe3O4-Mn3O4 nanocomposite as a Fenton-like catalyst. J Chem Technol Biotechnol 92(4):874–883. https://doi. org/10.1002/jctb.5072 Wang CB, Zhang WX (1997) Synthesizing nanoscale iron particles for rapid and complete dechlorination of TCE and PCBs. Environ Sci Technol 31(7):2154–2156. https://doi.org/10.1021/ es970039c Wang C, Baer DR, Amonette JE, Engelhard MH, Antony J, Qiang Y (2009a) Morphology and electronic structure of the oxide Shell on the surface of Iron nanoparticles. J Am Chem Soc 131(25):8824–8832. https://doi.org/10.1021/ja900353f Wang Q, Snyder S, Kim J, Choi H (2009b) Aqueous ethanol modified nanoscale zerovalent iron in bromate reduction: synthesis, characterization, and reactivity. Environ Sci Technol 43(9):3292–3299 Wang L, Yang J, Li Y, Lv J, Zou J (2016) Removal of chlorpheniramine in a nanoscale zero-valent iron induced heterogeneous Fenton system: influencing factors and degradation intermediates. Chem Eng J 284:1058–1067. https://doi.org/10.1016/j.cej.2015.09.042 Wang Y, Chen S, Yang X, Huang X, Yang Y, He E, Wang S, Qiu R (2017) Degradation of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) by a nano zerovalent iron-activated persulfate process: the effect of metal ions. Chem Eng J 317:613–622. https://doi.org/10.1016/j. cej.2017.02.070 Wei Z, Wei X, Wang S, He D (2014) Preparation and visible-light photocatalytic activity of α-Fe2O3/γ-Fe2O3 magnetic heterophase photocatalyst. Mater Lett 118:107–110. https://doi. org/10.1016/j.matlet.2013.12.051 Wei D, Wu S, Zhu Y (2017) Magnetic solid phase extraction based on graphene oxide/nanoscale zero-valent iron for the determination of tetracyclines in water and milk by using HPLC-MS/ MS. RSC Adv 7(70):44578–44586. https://doi.org/10.1039/c7ra08203g Wu W, He Q, Jiang C (2008) Magnetic Iron oxide nanoparticles: synthesis and surface functionalization strategies. Nanoscale Res Lett 3(11):397–415. https://doi.org/10.1007/s11671-­008-­9174-­9 Wu W, Wu Z, Yu T, Jiang C, Kim W (2015) Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications. Sci Technol Adv Mater 16(2):23501. https://doi.org/10.1088/1468-­6996/16/2/023501 Xia D, Lo IMC (2016) Synthesis of magnetically separable Bi2O4/Fe3O4 hybrid nanocomposites with enhanced photocatalytic removal of ibuprofen under visible light irradiation. Water Res 100:393–404. https://doi.org/10.1016/j.watres.2016.05.026 Xu L, Wang J (2011) A heterogeneous Fenton-like system with nanoparticulate zero-valent iron for removal of 4-chloro-3-methyl phenol. J Hazard Mater 186(1):256–264. https://doi. org/10.1016/j.jhazmat.2010.10.116 Xu J, Cao Z, Liu X, Zhao H, Xiao X, Wu J, Xu X, Zhou JL (2016) Preparation of functionalized Pd/Fe-Fe3O4@MWCNTs nanomaterials for aqueous 2,4-dichlorophenol removal: interactions, influence factors, and kinetics. J Hazard Mater 317:656–666. https://doi.org/10.1016/j. jhazmat.2016.04.063 Yan W, Vasic R, Frenkel AI, Koel BE (2012) Intraparticle reduction of Arsenite (As(III)) by nanoscale Zerovalent Iron (nZVI) investigated with in situ X-ray absorption spectroscopy. Environ Sci Technol 46(13):7018–7026. https://doi.org/10.1021/es2039695 Yan W, Lien H, Koel BE, Zhang W (2013) Iron nanoparticles for environmental clean-up: recent developments and future outlook. Environ Sci Processes Impacts 15(1):63–77. https://doi. org/10.1039/c2em30691c Yang Z, Gong X, Zhang C (2010) Recyclable Fe3O4/hydroxyapatite composite nanoparticles for photocatalytic applications. Chem Eng J 165(1):117–121. https://doi.org/10.1016/j. cej.2010.09.001 Yoon Y, Westerhoff P, Snyder SA, Wert EC (2006) Nanofiltration and ultrafiltration of endocrine disrupting compounds, pharmaceuticals and personal care products. J Membr Sci 270(1–2):88–100. https://doi.org/10.1016/j.memsci.2005.06.045

292

R. Cheng et al.

Zeng T, Yu M, Zhang H, He Z, Chen J, Song S (2017) Fe/Fe3C@N-doped porous carbon hybrids derived from nano-scale MOFs: robust and enhanced heterogeneous catalyst for peroxymonosulfate activation. Cat Sci Technol 7(2):396–404. https://doi.org/10.1039/C6CY02130A Zhang T, Li C, Ma J, Tian H, Qiang Z (2008) Surface hydroxyl groups of synthetic α-FeOOH in promoting OH generation from aqueous ozone: property and activity relationship. Appl Catal B Environ 82(1–2):131–137. https://doi.org/10.1016/j.apcatb.2008.01.008 Zhang Y, Li Y, Zheng X (2011) Removal of atrazine by nanoscale zero valent iron supported on organobentonite. Sci Total Environ 409(3):625–630. https://doi.org/10.1016/j. scitotenv.2010.10.015 Zhao X, Liu W, Cai Z, Han B, Qian T, Zhao D (2016) An overview of preparation and applications of stabilized zero-valent iron nanoparticles for soil and groundwater remediation. Water Res 100:245–266. https://doi.org/10.1016/j.watres.2016.05.019 Zhao H, Chen X, Li X, Shen C, Qu B, Gao J, Chen J, Quan X (2017) Photoinduced formation of reactive oxygen species and electrons from metal oxide-silica nanocomposite: an EPR spin-­ trapping study. Appl Surf Sci 416:281–287. https://doi.org/10.1016/j.apsusc.2017.04.088

Chapter 8

Plasmonics, Vibrational Nanospectroscopy and Polymers Mario D’Acunto

Abstract  Plasmonics is the branch of optics devoted to analyse optical configurations where the passage of light to, from through or near metal objects with subwavelength spatial features and the coupling of that light to a second object located a subwavelength distance from the first object. In the recent years, plasmonics has found application in photopolymerization, in the creation of hybrid (metal-polymer) nanostructures and nanophotochemistry. Analogously, the need to characterize spatially resolved chemical components on nanoscale stimulated the possible combination of Scanning Probe Microscopy with Raman spectroscopy. This led to the invention of Tip-Enhanced Raman Spectroscopy, whose use on polymers permits rigorous chemical analysis with nanometer spatial resolution. Keywords  Nanophotochemistry · Plasmon-based photopolymerization · Raman characterization · Polymer nanocomposites · Plasmonics

8.1  Introduction The interaction of light and matter at the nanoscale is a topic of rapidly growing scientific importance and technological relevance (Wang and Neogi 2010; Andrews 2008; Weiner and Nunes 2017). In particular, only to give few examples, nanoscale light-matter interactions are essential for the efficient conversion of light into chemical energy in biological light harvesting systems and for light-to-current conversion in artificial photovoltaic devices. Metallic nanostructures present amazing linear and nonlinear optical properties defined by the plasmon electronic behaviour. The chapter is devoted to describe (i) the plasmon-based photopolymerization and (ii) Raman characterization of polymer nanocomposites. M. D’Acunto (*) Consiglio Nazionale delle Ricerche, Istituto di Biofisica, CNR-IBF, Pisa, Italy e-mail: [email protected] © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_8

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Hence, plasmonics has become a fundamental key to understand and manipulate the nanoscale localization of light in the form of surface plasmons (Kawata 2001; Maier 2007). Hybrid nanomaterials are invested by great interest in nano-optics due to the possibility to realize systems with optical properties difficult or even impossible to create with homogenous composition nanostructures (Jana et al. 2015). Such properties include Fano resonances, coherent coupling, nonlinear optics, optical gain, solar energy conversion, photocatalysis (Shah et al. 2013; Wiederrecht et al. 2004; Patra et al. 2014; Choi et al. 2015; Sun et al. 2014; In et al. 2015; Huang et al. 2017). Many of such hybrid nanostructures involve polymers, in a special way (Tagliazucchi et al. 2012). Hybrid nanostructures offer the advantage of spatial control of organic materials close to the metallic surfaces and organic molecules. If the metal nanostructure is a metal nanoparticle, the plasmons are localized, hence one can change plasmon resonances making such hybrid system very useful for high resolution sensors. Analogously, anisotropy in the absorption and scattering cross-section of the metal nanoparticle can be induced. Plasmonic confinement of light plays a fundamental role in polymer photochemistry, in particular, for plasmon-assisted chemical reaction such as plasmon-induced polymerization (Zhou et  al. 2014a). Plasmon assisted chemical reactions can be schematically classified as (i) Molecular dissociation; (ii) Photoinduced switching of photochromes; (iii) Photo-polymerization. Plasmon-induced photo-­ polymerization by metal nanoparticles generates relevant optical effects including tunable nanoantennas with greater efficiencies, optical gain and lasing, and highly efficient nonlinear nanostructures. All such features are critical aspects for effective miniaturization of next-generation optical devices on nanoscale. Since hybrid nanomaterials require instrumentation able to detect optical properties on nanoscale, the combination of Scanning Probe Microscopy with vibrational spectroscopy led to the development of a near-field spectroscopic technique measuring both the topography and Raman spectrum with nanometer resolution spatial using a sharp metal. This device is known as Tip-Enhanced Raman Spectroscopy, TERS (Kumar et al. 2015). Fundamental advances have been made in the spatially resolved chemical analysis of polymer thin films using the TERS (Zhang et al. 2016). The chapter is organized as follows: in Sect. 8.2, the plasmon based photopolymerization is described presenting the most interesting recent achievements with a particular attention to current and next applications. Section 8.3 is devoted to describe the application of TERS to the nanoscale characterization of polymers materials. In turn, Sect. 8.4 deals out the current industrial applications of polymer plasmonics and Raman nanospectroscopy.

8.2  Plasmon Based Photo-Polimerization The first example of surface plasmon-enhanced photochemical reaction dates back to 1983, when Chen and Osgood produced a photoreaction consisting of a dissociation reaction of dimethyl cadmium (Me2Cd) on cadmium (Cd) nanoparticles (Chen

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and Osgoord 1705). Under an appropriate wavelength (257 nm), correspondent to plasmon resonance of Cd, the photodissociation of Me2Cd is observed. After this first experience, many other reactions have been driven by plasmons (Kim et  al. 1995; Juan et al. 2009; Ueno and Misawa 2013). A schematic sketch of the experimental setup of a plasmon photoinduced reaction is shown in Fig. 8.1a. Recently, plasmon photoinduced reaction was applied to the switching of azobenze between trans and cis isomers (Merino and Ribagorda 2012). This transition is reversible and can lead to the initiation of a chemical reaction by thermal and photochemical pathways. When coupled to metal nanoparticles illuminated with laser light, the local trans-cis isomerization after photoexcitation gives rise to a mass diffusion process due to thermal reorganization and reconfiguration of isomers (Hoffmann et  al. 2000). Another relevant example is the photoinduced polymerization of methacrylate monomers, Fig. 8.1b. In such process, the absorption of a photon leads to the excited singlet state of Eosin-Y (a fluorescent acidic compound which bind to or form salts with proteins containing amino acid residues such as arginine and lysine), and then to its triplet state by intersystem crossing. From the triplet state, a suitable dye can react with the amine to produce the first radical able to induce the free-­ radical polymerization of the methacrylate monomer. At this stage, a rapid crosslinking of the polymer network is usually observed when a trifunctional monomer is used (Deeb et al. 2011). In the right side of Fig. 8.1b, the inhibition processes due to oxygen dissolved in the photopolymer is shown. This is because oxygen can react with the radicals to create peroxide radicals that are not active for polymerization giving the possibility to have a precise control of the polymerization volume on nanoscale as a consequence of low consumption of oxygen at low intensity allowing for a continual replenishment from the surroundings. The polymerization process starts only when the oxygen concentration in the photopolymer is under a threshold value. Taking in account that the typical dye concentration is 0.5 wt%, and assuming a homogenous distribution of Eosin-Y within the photopolymer solution, it is possible to obtain a volume of 10 × 10 × 10 nm3 containing on average only four dye molecules, nearly 200MDEA and 6000C=C double bonds. As mentioned before, azobenzene is known to undergo a photoinduced transition between trans and cis isomers upon visible irradiation. Grafting azobenzene moieties on a polymer materials such as PMMA can design a material that can be patterned at the nanoscale producing spatially controlled irradiation, and eventually coupled to localized plasmons inducing nanostructuring, Fig.  8.2a, (Hubert et al. 2005). Diarylethene is a class of photochromes that has been applied to optical near-­ field irradiation with the purpose to produce molecular isomerization at the nanoscale. Such molecules can switch between two separate isomers states, an open and a closed form, Fig. 8.2 (Tsuboi et al. 2009). The isomerization is reversible and can be light induced. A controlled nanoscale photopolymerization triggered by local enhanced plasmon fields of silver nanoparticles has been proposed first by Ibn El Ahrach et al. (2007), Fig. 8.3. This study can be considered as a first example of nanophotochemistry of polymers. In addition, the hybrid system (polymer+silver nanoparticle) can

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Fig. 8.1  Schematic sketch of plasmon-based photoinduced chemical reactions in near-field optical regime, A. (Reproduced with permission from (Zhou et al. 2014a)). Basic components dealing out the photoinduced polymerization of methacrylate monomer involving Eosin-Y (2′, 4′, 5′, 7′-tetrabromo-fluorescin disodium salt, a fluorescent acidic compound) as dye and methyldiethanolamine (MDEA), (Reproduced with permission from (Deeb et al. 2011))

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Fig. 8.2 (a) Active azobenzene molecule moves under local plasmonic field induced by metal nanoparticle. (b) Molecular structure of diarylethene and spectra of open and closed forms. (Reproduced with permission from (Tsuboi et al. 2009))

Fig. 8.3  AFM images of hybrid nanostructures obtained making use of plasmonic photopolymerization on silver hemispherical nanoparticles, A and B, produced by e-beam lithography, C. The plasmon field associated to the silver nanoparticle is represented in D. (Adapted with permission from (Ibn El Ahrach et al. 2007))

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be used as a way of quantification of the field enhancement associated with localized surface plasmon resonance. In addition, the optical properties of the hybrid nanostructure can be controlled because the spatially inhomogeneous electromagnetic intensity distribution enhanced by the underlying surface plasmon leads to an anisotropic polymerization around the particles, introducing a certain tunability of plasmon resonance. The first photopolymerizable system involving plasmonic light consisted of a sensitizer dye –Eosin Y (2′, 4′, 5′, 7′-tetrabromo-fluorescin disodium salt)- (2%w/w), an amine cosynergist- MDEA- (from 4% to 10%), and a multifunctional acrylate monomer, the pentaerythritol triacrylate (PETIA) (Deeb et al. 2010). Disk-shaped silver nanoparticles with a diameter of 70 nm and a height of 50 nm. After deposition of polymer substrate, the sample is illuminated in normal incidence by a linearly polarized plane wave at λ = 514 nm, with a fluence of 20 mJ/cm2. The incident energy must be under the threshold so that polymerization occurs only around silver nanoparticles where local near fields are enhanced. Hence, the knowledge of the threshold values is of prime importance because ensures control of the procedure. Another vantage of such hybrid polymer and metal nanoparticle coupled system is the possibility to include new properties from the combining primitive systems. Such properties include nonlinear optical properties, doping with luminescent organic materials and chemical control of the refractive index. One critical question in plasmon photo-polymerization is that an indispensable component, such as the dye molecules, must be located within the near-field generated by the metal nanoparticle. As a consequence of the anisotropic distribution of dipolar mode plasmons supported by metal nanoparticles, the hybrid structure, metal and polymer, behaviour as a plasmonic nano-emitter (NE) (Kinkhabwala et al. 2009; Noginov et al. 2009), whose dye molecules are anisotropically spatially distributed. On the contrary to random or isotropic distribution of dye molecules around metal nanoparticles in hybrid light emitting nanostructures, the anisotropic spatial distribution of dye allows an optical selection of the molecules by using incident polarization (Zhou et  al. 2014b). Dye molecules must participate in the photopolymerization process and prevent possible photobleaching, so the reasonable choice is to use quantum dots (QDs) (Elliott et al. 2013), grafted with covalent bonds to polymers. Beyond the fluorescence spectroscopy, surface enhanced Raman scattering (SERS) can be used to probe the presence of molecules at the plasmonic hot spots. Methylene Blue (MB) is known to be a good SERS probe. In Fig. 8.4, the SERS signal of a hybrid system composed by nanodimer and photopolymer is represented (Zhou et  al. 2015). In such hybrid system, a nanodimer, formed by two gold nanoparticles, contains in its gap a MB as an active medium. If the sample is illuminated by a wavelength correspondent to the dimer plasmon resonance, the system present a polarization sensitivity as a result from a tunable spatial overlap between the plasmonic near-field generated by the nanodimer and the active molecules. Stimulated by the results obtained with SERS spectroscopy, the next section is devoted to detail the useful application to polymers of Tip-Enhanced Raman Spectroscopy.

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Fig. 8.4  Example of polarization-dependent SERS signals from MB molecules located in a nanodimer gap. The SERS signal is obtained with an incident polarization along the gap (Sx) and with a polarization perpendicular to the gap (Sy). The signal Sx is approximately 5 times higher than the signal Sy. Inset SEM image shows the topography of the hybrid system. (Reprinted with permission from (Zhou et al. 2015))

8.3  V  ibrational Spectroscopies and Tip Enhanced Raman Spectroscopy Applied to Polymers Raman and infrared (IR) spectroscopies are two techniques providing complimentary vibrational information and can be renamed as Vibrational Spectroscopies (VS) (De Caro 2012). Among the large number of applications of VS, the applications to polymeric systems meet a special interest in a wide range of scientific branches and several high impact technologies (Everall et al. 2007). This is because in contrast to small-molecule compounds, polymers are composed by atoms all linked together one each other to form long chains. Such long chains present additional vibrational modes that do not exist in small-molecule compounds. When IR and Raman spectroscopic techniques are employed in combination, the results are more meaning than can be obtained using a single technique. The complimentary nature of the IR and Raman data arises from the difference in selection rules governing the vibrational energy levels. This complimentary use can overwhelm some limiting features of both the single vibrational techniques. In Raman spectroscopy, for example, one problem is represented by the fact that most polymers strongly fluoresce under laser irradiation. This problem is partially solved by using Fourier transform and resonance Raman techniques. Because of this and other difficulties associated with Raman spectroscopy, the quality of Raman spectra of polymers is generally less than that of IR spectra. Analogously, a problem unique to transmission IR spectroscopy is that polymers are very strong absorbers of IR radiation. To fall in the linear region of Beer’s law, an extremely thin polymer film must be used in transmission. As a consequence, the most used industrial IR

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techniques are reflectance techniques such as attenuated total reflectance or reflection-­absorption spectroscopy (Snively and Koenig 1999). Using a combination of IR and Raman spectroscopy is possible to gather essential information on polymers structure. For example, polymers are not usually associated to conformations with a center of symmetry. To have a center of symmetry is a typical characteristic of low-molecular-weight substances, like ethylene or benzene (Xue 1994). For molecules with a center of symmetry, no vibrational frequencies are common to the IR and Raman spectra. This principle is called the mutual exclusion principle (Koenig 1999). Polyethylene (PE) has a center of symmetry, hence the observed IR and Raman lines do not coincide in frequency. Theory predicts that eight modes for PE are active in the Raman while only five for IR. Thus, the combination of VS techniques are fundamental for structural determination of polymers with a center of symmetry because the Raman and IR lines are mutually exclusive in frequency. For example, polyethylene sulfide (PES) consists of a succession of (-CH2CH2SCH2CH2S-) repeat units. The conformational structure of PES provides the CC, CS, SC, CC, CS and SC bonds that are trans, gauche (right), gauche (right), trans, gauche (left), gauche (left), respectively. If PES has a center of symmetry, as prescribed by theory, observed IR and Raman frequencies are mutually exclusive. However, if PES exists in a helical form like polyethylene oxide (PEO), it does not have a center of symmetry, and many frequencies are theoretically expected to be not coincident in the Raman and IR spectra. This is what is observed experimentally. PEO has 20 coincident Raman and IR bands, on the contrary, PES has only two accidentally coincident frequencies due to residual degeneracies. Such accidental degeneracies arise when the frequency differences between modes are too small to be resolved. Hence, PEO presents a C-C bond taking the gauche form, and the C-O bond taking the trans form, but in PES, the C-C bond takes the trans form, and the C-S bond takes the gauche form (Koenig 1999). The experience shows that all elements of symmetry influence the selection rules. In addition, measurements of polarization in Raman spectroscopy and dichroic behavior in IR spectroscopy can be used to classify the vibrational properties of polymer chains (Pradier and Chabal 2011). Although the VS gains more information when used in combination, the single spectroscopic techniques can offer further information on specific polymer properties. An interesting application of Raman spectroscopy is the determination of the modulus of pure crystalline forms of a polymer. Since Raman is very sensitive to the longitudinal acoustic vibrational modes of simple polymer chains, using a combination of normal coordinate analysis and experiment, the modulus of pure crystalline forms of simple straight-chain polymers, such as PE and poly(oxymethylene) have been determined (Snively and Koenig 1999). This experimental strategy is complimentary to mechanical analysis because it gives insight into what is occurring at the molecular level during mechanical deformation. TERS is a near-field spectroscopic technique measuring both the topographic information and Raman spectrum with nanometer spatial resolution using a sharp metal tip (Stöckle et  al. 2000; Anderson 2000; Hayazawa et  al. 2000; Anderson et al. 2005; Steidtner and Pettiger 2008), Fig. 8.5. The sharp metal tip acts like a

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Fig. 8.5  Schematic sketch of a TERS. The AFM tip coated with silver or gold is brought close to a sample. When excited with a laser the molecules will yield spectra with greatly enhanced Raman signal intensity. On contrary to SERS, in TERS the enhancement is controlled and remains spatially limited to surface under investigation allowing optical spatial resolution down to ~10 nm

Fig. 8.6  Two working modalities for a TERS, transmission mode (a), and reflection mode (b)

single hot spot which enhances locally the Raman scattering from the scanned sample area. At best experimental conditions, it is possible to achieve single-molecule sensitivity with a lateral spatial resolution, being determined by the tip apex radius, of ~10 nm, and a penetration depth of ~20 nm, making TERS an important tool for nanoscale chemical analysis. In the last decade, TERS has been successfully applied in different disciplines such as life science (Neugebauer et al. 2006), surface science (Ren et al. 2005) and material science (Hartschuh et al. 2003), thanks to the possibility to work with two basic modalities, such transmission mode or reflection mode, Fig. 8.6. TERS have found application in the determination of polymer blends and polymer nanocomposites. This is because traditional analytical methods are inadequate to determine polymer properties at a surface level or with nanometer resolution. AFM with its various imaging modes is commonly used to study surfaces with

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nanometer resolution, but unfortunately, such imaging methods are unable to identify chemical composition. Another spectroscopic technique largely employed for the chemical determination of polymers is the X-ray photoelectron spectroscopy (XPS). XPS demonstrated excellent depth resolution, generally limited to few nanometers, but with an inadequate lateral resolution, being in standard spectrometers of several micrometers. All such limitations can be overwhelm using a TERS. A basic study of surface polymers on nanoscale has been made by Yeo et  al. (2009). They considered an immiscible polystyrene(PS) and polyisoprene (PI) polymer blend thin film was chosen as the sample of case study. Blended in opportune combinations, these polymers are employed as components in hot-melt adhesives and sealants (Utracki and Wilkie 2014), modifiers for general compounding and tribological applications (D’Acunto et al. 2015). The results of the application of combined AFM and Raman are presented in Fig. 8.7. The AFM images present

Fig. 8.7 (a) AFM topography image of a PS and PI film, (b) correspondent sequence of TERS spectra collected from the positions labelled in (a). (c) AFM topography image of a hexane-washed PS and PI film, (b), and correspondent sequences of TERS spectra collected from the positions labelled in (c). (Adapted with permission from (Yeo et al. 2009))

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the immiscibility of the two polymers. The immiscibility of the two polymers is a consequence of lower surface tension of PI, with respect to PS, so that PI enriches the polymer and air interface. TERS spectra can be collected on any single position of the separate layers of PS and PI thin films. TERS spectra are able to discriminate between the two polymers, Figs.  8.7b, c. TERS peaks can be assigned to PS(1002 cm−1) and PI(1664 cm−1), in addition, the inhomogeneity of the polymers film on the nanometer scale are evidenced, because PS and PI layers are not perfectly uniform in their thicknesses. The ability to detect small drifts or AFM tip wear is another peculiarity of TERS (Hartschuh et al. 2003). AFM tip wear is a crucial question of AFM measurements provoking in many cases, underestimated artefacts during measurement. Generally, the control of tip wear can be made by using Scanning Electron Microscope (SEM) prior and after an AFM experiment. Unfortunately, small changes to the tip may not to be observable by SEM. In addition, electron-beam-induced deposition of carbon of the AFM tip is an inevitable consequence of SEM check, so making unusable the tip for further TERS measurement. In Fig. 8.8 is shown the basic results obtained in an AFM tip wear testing using a TERS.  In such experiment, five positions were selected and one spectrum was collected for each position, and this process was repeated three more times (Yeo et al. 2009). Spectra from the first and last positions, marked as positions 1 and 2 in Fig. 8.8a, are shown in Fig. 8.8b. Any spectrum was collected with an acquisition time of 60s, so that all the spectra were acquired involving tens of minutes after the first. The band intensities represented in Fig. 8.8b remain identical throughout of each point demonstrating the absence of tip wear and drift throughout the TERS measurement. Xue et al. (2011) added to the TERS technique the ability to perform mapping showing for the first time the high resolution Tip-Enhanced Raman mapping (TERM). TERM was first applied to a polymer system composed by poly(methyl methacrylate) (PMMA)/poly(styrene-co-acrylonitrile) (SAN) thin films. In TERM measurement, the TERS linear enhancement is optimized in terms of maximum Raman intensity using a cone-shaped AFM tip. The optimization of Raman enhancements with scanning strategies make possible a short exposure time for high-­ resolution TERM measurements. The phase separation behaviour of PMMA-SAN thin films can be monitored by chemical recognition of local composition, Fig. 8.9. Typical values of TERM measurements made by Xue et  al. are a scan area of 30μm × 30μm using 150 × 150 points, which correspond to a nominal pixel size of 200 nm (Xue et al. 2011). The exposure time can be set to 10s/point. Nowadays, the improved detection sensitivity of TERS and TERM allows the detailed chemical analysis at the interface and interphase regions with nanoscale sizes. Variables such as interface widths, concentration gradients of each component, phase inversion and local Tg can be characterized in an excellent way, impossible to be measured with other techniques with such high-resolution ability.

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Fig. 8.8 (a) AFM topography image of a PS protrusion in a PS and PI film. (b) Zoomed view of two sets of TERS spectra taken at positions labelled by 1 and 2. Each set consists of four spectra collected at different times. (c) AFM topography image of a PS and PI film. (d) TERS intensities of the PS (1002 cm−1, blue trace) and PI (1664 cm−1, red trace) plotted as a function of the tip position on the sample. (Adapted with permission from (Yeo et al. 2009))

8.4  I ndustrial Impact of Polymer Plasmonics and Raman Nanospectroscopy As mentioned in the introduction, plasmonics represents a rapidly growing research field, pursued to impact a wide range of applications ranging from optical spectroscopy, to optical communication technologies, photovoltaics, or sensors devices and chemical analytical technologies (Kawata 2001; Maier 2007; Reimhult and Höök 2015). The highest impact of these applications is expected for those nanostructures

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Fig. 8.9  TERM images of PMMA and SAN blends displayed at different annealed at 250 °C for 2 min, (a) and for 5 min (b). The Raman bands at 1002 cm−1 correspond to SAN, while the Raman intensity of Raman bands at 800 cm−1 correspond to PMMA. (Reprinted with permission from (Xue et al. 2011))

that are optically active. Active plasmonic nanostructures can be designed combining different materials in order to change their refractive index, absorption, or volume in response to environmental stimuli including light, temperature, pH, or current (Dionne et  al. 2015). Hybrid plasmonic structures that utilize responsive polymers are the most suitable nanostructures for being used in a wide range of applications (Azzaroni and Szleifer 2018). Here, we focus only to some of such applications, those with higher industrial impact. One of such applications is given by the optical flexible active nanocomposites (Larsson et al. 2012; Chen et al. 2012; Kumari et al. 2017). Recently, using plasmonic nanoslit arrays, Xu et  al. demonstrated high contrast, fast monochromatic and full-colour electrochromic switching employing two different electrochromic polymers, polyaniline (PANI) and poly(2,2-dymethyl-3,4 propylenedioxythiophene) (PolyProDOT-Me2) (Xu et al. 2016). Unlike transition-metal-oxide electrochromic materials, usually sputter coated, or inorganic polymers, difficult to deposit uniformly, both PANI and PolyProDOT-Me2 polymers can be electrodeposited as conformal, extremely thin coatings on metal structures with totally controlled thicknesses, generating scatter-free propagation of SPPs with maximum interaction with the electrochromic films. Consequently, the plasmonic electrochromic switchable configurations retain the advantages of both fast switching speed and high optical contrast (Xu et al. 2016). Details on electrochromic switches enabled by plasmonic can be found here (https://patentimages.storage.googleapis.com/7f/48/16/09db51 bd21d6bc/US20130201544A1.pdf; https://patentimages.storage.googleapis. com/50/ae/f0/207e41550e7abd/US7256923.pdf; https://patents.google.com/patent/ EP2128598A1/pt). Another industrial application of high impact is the improvement of sensor devices by the combination of highly localized single nanoparticle plasmons and polymer molecular imprinting (Kiremitler et al. 2017; Tokareva et al. 2006). The advantage of such combination in a myriad of chemical and physical sensor devices can be detected with high sensitivity, if taking place within the enhanced field region

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that creates a spatially nano-confined sensing volume. Processes within the sensing volume can be detected if they involve a change of the polarizability of the matter localized within it. In addition, they are identified as a slight change of the Local Surface Plasmon resonance frequency, i.e. a peak shift in the extinction spectrum (Jackman et al. 2017). The latter constitutes the fundament of nanoplasmonic sensing, which over the last two decades has diversified into a very promising experimental platform technology. For example, understanding of the phase transition dynamics of substrate brushes of thermoresistive poly(N-isopropylacrylamide, pNIPAM) is crucial for cell substrates with spatially selective affinity or high resolution drug detection (Winkler et al. 2015). Unfortunately, characterization of the brushes phase transition time is hampered by the low amount of involved pNIPAM. Making use of gold nanorods, Winkler et  al., were able to measure a transition time of 160 ± 20μs for a 30 nm thick substrate tethered brush (Winkler et al. 2015). Polymer swelling-shrinking transition in response to external stimuli is a crucial question in many polymer applications, such as packaging, barrier effects, membrane, drug release and medical implants. Plasmonic nanostructures have been quite extensively used to monitor the swelling-shrinking transition in response to changes in pH, temperature or solvent polarity. The first application of plasmonic sensing to quantitatively follow the swelling-shrinking phase transition in a polymer was presented by Tian et  al. in 2012. They used gold nanorods to probe the growth and swelling of polyelectrolyte multilayers (PEM). The growth of the PEM was monitored with single layer sensitivity. Using the plasmon peak shift in air, Tian and co-workers measured the refractive index sensitivity of the nanorods to be 153 nm/ RIU. It is remarkable that such authors were able to calculate the refractive index of the swollen polymer layer without an a priori knowledge of the thickness of the swollen polymers layers (Tian et al. 2012). Analogously to sensing applications, where the high level of sensitivity is essentially guaranteed by the extinction cross section of the plasmonic component, vibrational nanospectroscopy of polymers takes advantage from the combination with plasmonics nanoparticles being able to enhance the Raman signal by several orders of magnitude. Raman spectroscopy has been mainly used for decades for research purposes instead of routine analysis. The recent advances in Raman instrumentation now enable rapid acquisition of spectra with equipment, which is much more user friendly if compared to the past. Raman spectra can be utilized in industrial applications for (i) Monitoring production of a product; (ii) Identifying contaminants in a production process; (iii) Confirming incoming product. By analysing Raman spectra an unknown polymer can be easily identified. In addition, Raman spectra allow the check of the degree of polymerization and show higher sensitivity to the presence of unpolymerized -C=C- band, compared to IR spectroscopy. SERS and TERS techniques exhibit highly localized chemical sensitivity, making them ideal for monitoring the industrial quality of products. SERS substrates for large industrial application have been fabricated and largely employed (https://patents.google.com/patent/US9001322; https://patents.google.com/patent/WO201603 6409A1/en; https://patentimages.storage.googleapis.com/01/ce/2a/1c30666bc9c 6d6/US9377409.pdf). One industrial branch where SERS and TERS can find

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application is catalysis (Hartman et al. 2016). Catalyst structures, adsorbates, and reaction intermediates can be observed in manufacturing control in low quantities at hot spots where electromagnetic fields are the strongest. Another possible fast track industrial application of TERS is the control of polymers blends. Recently, Agapov et al. were able to identify individual isotopes of PS (polystyrene) in a miscible, binary blend making use of a TERS (Agapov et al. 2015). Thanks to the extraordinary characteristics of Raman spectroscopy, nowadays it is easy to imagine that in the next few years, we will see a further and rapid development of the use of SERS and TERS in industrial applications for the control and production of smart and multifunctional polymers.

8.5  Conclusions Plasmonics is the branch of optics devoted to analyse nanoscale optical configurations where light interacts with subwavelengths metal structures producing high confinements of electromagnetic fields. In the recent years, plasmonics has been applied to photopolymerization, to the creation of hybrid (metal-polymer) nanostructures and to nanophotochemistry. Analogously, the advent of TERS, a device combining Scanning Probe Microscopy with Raman spectroscopy, has given the possibility to perform rigorous chemical analysis with nanometer spatial resolution on polymers and nanocomposites. The purpose of the chapter was to give as far as possible an adequate description of (i) the plasmon-based photopolymerization; (ii) Raman characterization of polymer nanocomposites and, in turn, (iii) the industrial impact of both polymer plasmonics and Raman nanospectroscopy. Acknowledgments  The author wishes to thank COST Action Nanospectroscopy MP1302 for useful support.

References Agapov RL, Scherger JD, Sokolov AP, Foster MD (2015) Identification of individual isotopes in a polymer blend using tip enhanced Raman spectroscopy. J Raman Spectrosc 46:447–450. https://doi.org/10.1002/jrs.4671 Anderson MS (2000) Locally enhanced Raman spectroscopy with an atomic force microscope. Appl Phys Lett 76:3130. https://doi.org/10.1063/1.126546 Anderson N, Hartschuh A, Cronin S, Novotny L (2005) Nanoscale vibrational analysis of single-­ walled carbon nanotubes. J Am Chem Soc 127:2533. https://doi.org/10.1021/ja045190i Andrews DL (2008) Structured light and its applications. Elsevier. https://doi.org/10.1016/B978-­ 0-­12-­374027-­4.50001-­2 Azzaroni O, Szleifer I (2018) Polymer and biopolymer brushes: for materials science and biotechnology, vol 2. Wiley, ISBN:9781119455042

308

M. D’Acunto

Chen CJ, Osgoord RM (1705) Direct observation of the local-field-enhanced surface photochemical reactions. Phys Rev Lett 50:1983. https://doi.org/10.1103/PhysRevLett.50.1705 Chen Q, Martin C, Cumming DRS (2012) Transfer printing of Nanoplasmonics devices onto flexible polymer substrates from a rigid stump. Plasmonics 7:75–761. https://doi.org/10.1007/ s11468-­012-­9370-­4 Choi BS, Jeong JS, Yoon K-H, Kim KS, Kim HS, Park MR, Kwon OK, Lee HK, Chung YC (2015) Evaluation of chirp reduction in polymer-based tunable external-cavity lasers. IEEE J Quantum Electron 51:200315 D’Acunto M, Dinelli F, Pingue P (2015) Nanoscale rippling on polymer surfaces induced by AFM manipulation. Beilstein J Nanotechnol 6:2278–2289. https://doi.org/10.3762/bjnano.6.234 De Caro D (2012) Vibrational spectroscopy. InTech, Croatia. https://doi.org/10.5772/1345 Deeb C, Bachelot R, Plain J, Baudrion AL, Jradi S, Bouhelier A, Soppera O, Jain PK, Huang L, Ecoffet C, Balan L, Royer P (2010) Quantitative analysis of localized surface plasmons based on molecular probing. ACS Nano 4:4579–4586. https://doi.org/10.1021/nn101017b Deeb C, Ecoffet C, Bachelot R, Plain J, Bouhelier A, Soppera O (2011) Plasmon-based free-­ radical photopolymerization: effect of diffusion on nanolithography processes. J Am Chem Soc 133:10535–10542. https://doi.org/10.1021/ja201636y Dionne JA, Baldi A, Baum B, Ho CS, Jankovic V, Naik GV, Narayan T, Scholl JA, Zhao Y (2015) Localized fields, Global impact: industrial applications of resonant plasmonic materials. MRS Bull 40:1138–1145. https://doi.org/10.1557/mrs.2015.233 Elliott AM, Ivanova OS, Williams CB, Campbell TA (2013) Inkjet printing of quantum dots in photopolymer for use in additive manufacturing of nanocomposites. Adv Eng Mater 15:903–907. https://doi.org/10.1002/adem.201300020 Everall NJ, Griffiths PR, Chalmers JM (2007) Vibrational spectroscopy of polymers: principles and practice. Wiley, ISBN:978-0-470-01662-6 Hartman T, Wondergem CS, Kumar N, van der Berg A, Weckhuysen BM (2016) Surface- and tip-enhanced Raman spectroscopy in catalysis. J Phys Chem Lett 7:1570–1584. https://doi. org/10.1021/acs.jpclett.6b00147 Hartschuh A, Sanchez EJ, Xie XS, Novotny L (2003) High-resolution near-field Raman microscopy of single-walled carbon nanotubes. Phys Rev Lett. https://doi.org/10.1103/ PhysRevLett.90.095503 Hayazawa N, Inouye Y, Sekkat Z, Kawata S (2000) Metallized tip amplification of near-field Raman scattering. Opt Commun 183:333. https://doi.org/10.1016/S0030-­4018(00)00894-­4 Hoffmann K, Resch-Genger U, Marlow F (2000) Photoinduced switching of nanocomposites consisting of azobenzene and molecular sieves: investigation of the switching states. Microporous Mesoporous Mater 41:99–106. https://doi.org/10.1016/S1387-­1811(00)00277-­8 Huang F, Li Z, Yan A, Zhao H, Feng H, Wang Y (2017) Novel Nb3O7F/WS2 hybrid nanomaterials with enhanced optical absorption and photocatalytic activity. Nanotechnology 28:275707. https://doi.org/10.1088/1361-­6528/aa744d Hubert C, Rumyansteva A, Lerondel G, Grand J, Kostcheev S, Billot L, Vial A, Bachelot R, Royer P (2005) Near-field photochemical imaging of noble metal nanostructures. Nano Lett 5:615–619. https://doi.org/10.1021/nl047956i Ibn El Ahrach H, Bachelot R, Vial A, Lerondel G, Plain J, Royer P, Soppera O (2007) Spectral degeneracy breaking of the plasmon resonance of single metal nanoparticles by nanoscale near-field photopolymerization. Phys Rev Lett 98:107402. https://doi.org/10.1103/ PhysRevLett.98.107402 In S, Mason DR, Lee H, Jung M, Lee C, Park N (2015) Enhanced light trapping and power conversion efficiency in ultrathin plasmonic organic solar cells: a coupled optical-electrical Multiphysics study ion the effect of nanoparticle geometry. ACS Photonics 2:78. https://doi. org/10.1021/ph500268y Jackman JA, Ferhan AR, Cho NJ (2017) Nanoplasmonic sensors for biointerfacial science. Chem Soc Rev 46:3615–3660. https://doi.org/10.1039/C6CS00494F Jana B, Bhattacharyya S, Patra A (2015) Conjugated polymer P3HT-Au hybrid nanostructures for enhancing photocatalytic activity. Phys Chem Chem Phys 17:15392–15399. https://doi. org/10.1039/C5CP01769F

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Juan ML, Plain J, Bachelot R, Vial A, Royer P, Gray SK, Montgomery JM, Wiederrecht GP (2009) Plasmonic electromagnetic hot spots temporally addressed by photoinduced molecular displacement. J Phys Chem A 113:4647–4651. https://doi.org/10.1021/jp8114435 Kawata S (2001) Near-field optics and surface plasmon polaritons. Springer, ISBN: 978-3-540-41502-2 Kim DY, Lian L, Jiang XL, Shivshankar V, Kumar J, Tripathy SK (1995) Polarized laser induced holographic surface relief gratings on polymer films. Macromolecules 28:8835–8839. https:// doi.org/10.1021/ma00130a017 Kinkhabwala A, Yu Z, Fan S, Avlasevich Y, Müllen K, Moerner WE (2009) Large single-molecule fluorescence enhancements produced by a bowtie nanoantennas. Nat Photonics 3:654–657. https://doi.org/10.1038/nphoton.2009.187 Kiremitler NB, Pekdemir S, Patarroyo J, Karabell S, Torun I, Puntes VF, Onses MS (2017) Assembly of plasmonic nanoparticles on nanopatterns of polymer brushes fabricated by electrospin nanolithography. ACS Macro Lett 6:603–608. https://doi.org/10.1021/acsmacrolett.7b00288 Koenig JL (1999) Spectroscopy of polymers, II edn. Elsevier, ISBN: 9780444100313 Kumar N, Mignuzzi S, Su W, Roy D (2015) Tip-enhanced Raman spectroscopy: principles and applications. Eur Phys J 2:9. https://doi.org/10.1140/epjti/s40485-­015-­0019-­5 Kumari S, Mohapatra S, Moirangthem RS (2017) Development of flexible plasmonic plastic sensor using nanograting textured laminating film. Mater Res Express 4:025008. https://doi. org/10.1088/2053-­1591/aa5b5e Larsson EM, Syrenova S, Langhammer C (2012) Nanoplasmonic sensing for nanomaterials science. Nano 1:249–266. https://doi.org/10.1515/nanoph-­2012-­0029 Maier SA (2007) Plasmonics. In: Fundamental and applications. Springer, ISBN: 978-0-387-33150-8 Merino E, Ribagorda M (2012) Control over molecular motion using the cis-trans photoisomerization of the azo group. Beilstein J Org Chem 8:1071–1090. https://doi.org/10.3762/bjoc.8.119 Neugebauer U, Rösch P, Schmitt M, Popp J, Julien C, Rasmussen A, Budich C, Deckert V (2006) On the way to nanometer-sized information of the bacterial surface by tip-enhanced Raman spectroscopy. ChemPhysChem 7:1428–1430. https://doi.org/10.1002/cphc.200600173 Noginov MA, Zhu G, Belgrave AM, Bakker R, Shalaev VM, Narimanov EE, Stout S, Herz E, Suteewong T, Wiesner U (2009) Demonstration of a spaser-based nanolaser. Nature 460:110–113. https://doi.org/10.1038/nature08318 Patra BK, Guria AK, Dutta A, Shit A, Pradhan N (2014) Au-SnS hetero nanostructures: size of au matters. Chem Mater 26:7194–7200. https://doi.org/10.1021/cm5039914 Pradier CM, Chabal YJ (2011) Biointerface characterization by advanced IR spectroscopy. Elsevier, ISBN. 9780444535580 Reimhult E, Höök F (2015) Design of surface modifications for nanoscale sensor applications. Sensors 15:1635–1675. https://doi.org/10.3390/s150101635 Ren B, Picardi G, Pettinger B, Schuster R, Ertl G (2005) Tip-enhanced Raman spectroscopy of benzenethiol adsorbed on au and Pt single-crystal surfaces. Angew Chem Int Edit 44:139–142. https://doi.org/10.1002/anie.200460656 Shah RA, Scherer NF, Pelton M, Gray SK (2013) Ultrafast reversal of a Fano resonance in a plasmon-­exciton system. Phys Rev B 88:075411. https://doi.org/10.1103/PhysRevB.88.075411 Snively CM, Koenig JL (1999) Polymer applications of IR and Raman spectroscopy, in reference module in chemistry, molecular sciences, chemical engineering. Academic, ISBN:978-0-12-803224-4 Steidtner J, Pettiger B (2008) Tip-enhanced Raman spectroscopy and microscopy on single dye molecules with 15nm resolution. Phys Rev Lett 100:236101. https://doi.org/10.1103/ PhysRevLett.100.236101 Stöckle RM, Suh YD, Deckert V, Zenobi R (2000) Nanoscale chemical analysis by tipenhanced Raman soectroscopy. Chem Phys Lett 318:131. https://doi.org/10.1016/ S0009-­2614(99)01451-­7 Sun SS, Brooks J, Nguyen T, Harding A, Wang D, David T (2014) Novel organic and polymeric materials for solar energy conversions. Energy Procedia 57:79–88. https://doi.org/10.1016/j. egypro.2014.10.011

310

M. D’Acunto

Tagliazucchi M, Blaber MG, Schatz GC, Weiss EA, Szleifer I (2012) Optical properties of responsive hybrid au@polymer nanoparticles. ACS Nano 6:8397–8406. https://doi.org/10.1021/ nn303221y Tian L, Fei M, Kattemenu R, Abbas A, Singamaneni S (2012) Gold nanorods as nanotransducers to monitor the growth and swelling of ultrathin polymer films. Nanotechnology 23:255502. https://doi.org/10.1088/0957-­4484/23/25/255502 Tokareva I, Tokarev I, Minko S, Hutter E, Fendler JH (2006) Ultrathin molecularly imprinted polymers sesnors employing enhanced transmission surface plasmon resonance spectroscopy. Chem Commun 42:3343–3345. https://doi.org/10.1039/B604841B Tsuboi Y, Shimizu R, Shoji T, Kitamura N (2009) Near-infrared continuous-wave light driving a two-photon photochromic reaction with the assistance of localized surface plasmon. J Am Chem Soc 131:12623–12627. https://doi.org/10.1021/ja9016655 Ueno K, Misawa H (2013) Surface plasmon-enhanced photochemical reactions. J Photochem Photobiol C: Photochem Rev 15:31–52. https://doi.org/10.1016/j.jphotochemrev.2013.04.001 Utracki LA, Wilkie CA (2014) Polymer blends handbook. Springer, Berlin, ISBN: 978-94-007-6063-9 Wang Z, Neogi A (2010) Nanoscale photonics and optoelectronics. Springer, ISBD: 978-1-4419-7233-0 Weiner J, Nunes F (2017) Light-matter interaction. Physics and engineering at the nanoscale, II edn. Oxford Press, ISBN: 978-0-19-879667-1 Wiederrecht GP, Wurtz GA, Hranisavljevic J (2004) Coherent coupling of molecular excitons to electronic polarizations of noble metal nanoparticles. Nano Lett 4:2121–2125. https://doi. org/10.1021/nl0488228 Winkler P, Belitsch M, Tischler A, Häfele V, Ditlbacher H, Krenn JR, Hohenau A, Nguyen M, Felidj N, Mangeney C (2015) Nanoplasmonic heating and sensing toreveal the dynamics of thermoresponsive polymer brushes. Appl Phys Lett 107:141906. https://doi.org/10.1063/1.4932968 Xu T, Walter EC, Agrawal A, Bohn C, Velmurugan J, Zhu W, Lezec HJ, Talin AA (2016) High-­ contrast and fast electrochromic switching enabled by plasmonics. Nat Comm 7:10479. https:// doi.org/10.1038/ncomms10479 Xue G (1994) Laser Raman spectroscopy of polymeric materials. Prog Polym Sci 19:317–388. https://doi.org/10.1016/0079-­6700(94)90009-­4 Xue L, Li W, Hoffmann GG, Goossens JGP, Loos J, de With G (2011) High-resolution chemical identification of polymers blend thin films using tip-enhanced Raman mapping. Macromolecules 44:2852–2858. https://doi.org/10.1021/ma101651r Yeo BS, Amstad E, Schmid T, Stadler J, Zenobi R (2009) Nanoscale probing of a polymer-blend thin film with tip-enhanced Raman spectroscopy. Small 5:952–960. https://doi.org/10.1002/ smll.200801101 Zhang Z, Sheng S, Wang R, Sun M (2016) Tip-enhanced Raman spectroscopy. Anal Chem 88:9328–9346. https://doi.org/10.1021/acs.analchem.6b02093 Zhou X, Soppera O, Plain J, Jradi S, Sun XW, Demir HV, Yang X, Deeb C, Gray SK, Wiederrecht GP, Bachelot R (2014a) Plasmon-based photopolymerization: near-field probing, advances photonic nanostructures and nanophotochemistry. J Opt 16:114002. https://doi. org/10.1088/2040-­8978/16/11/114002 Zhou X, Deeb C, Vincent R, Lerond T, Adam PM, Plain J, Wiederrecht GP, Charra F, Fiorini C, Colas de Francs G, Soppera O, Bachelot R (2014b) Polarization-dependent fluorescence from a anisotropic gold/polymer hybrid nanoemitter. Appl Phys Lett 104:023114. https://doi. org/10.1063/1.4861898 Zhou X, Deeb C, Kostcheev S, Wiederrecht GP, Adam PM, Beal J, Plain J, Gosztola DJ, Grand J, Felidj N, Wang H, Vial A, Bachelot R (2015) Selective functionalization of the nanogaps of a plasmonic dimer. ACS Photonics 2:121–129. https://doi.org/10.1021/ph500331c

Chapter 9

Phyto-Nanosensors: Advancement of Phytochemicals as an Electrochemical Platform for Various Biomedical Applications Mansi Gandhi, Shiao-Shing Chen, Saikat Sinha Ray, Nilesh Kumar Jaiswal, and Shivendu Ranjan

Abstract  From galenical to genomical time, there has always been an attempt to avail phytonutrients in medicines, with an urge to incorporate environmental friendly approach. The phytonutrients are regarded by different names like herbs, spices, phytochemicals, plant polyphenols, etc. They can be incorporated as a signaling system, mediator or transducer for sensor applications. The sensors produced using them are comparatively green, eco-friendly, efficient in terms of cost too. We reviewed the major key points of phytochemicals for electrochemical applications, facilitating the blooming scientists to include phytonutrients  in the electro-­ analytical field. In this context different sub-heading are incorporated relating to introduction of various phytochemicals and their scientific literatures, electrochemical aspects of phytonutrients developed over time to study and examine them, their redox behavior and analysis parameters. Apart from this, we reviewed the issues creating a threshold in its progress, which are elaborately discussed. Even M. Gandhi (*) Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology, Tamil Nadu, India Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei, Taiwan S.-S. Chen · S. S. Ray Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei, Taiwan N. K. Jaiswal Department of Macro and Nanoelectronics, Vellore Institute of Technology, Tamil Nadu, India S. Ranjan Faculty of Engineering and the Built Environment, University of Johannesburg, Johannesburg, Gauteng, South Africa © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_9

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their qualitative and quantitative assessment using polyphenols as a sensor has been established and reported in this regard. The recent developments have evolved the concept, thus making their usage suitable and realistic. Finally, challenges and their future aspects are equally highlighted and discussed. Hence, the global knowledge regarding Indian Herbs or Phytochemicals could be improved by the particulars presented in this chapter. Keywords  Phytonutrients · Electrochemical profiling · Environmental friendly · Redox behavior · Sensor

9.1  Introduction Nature offers a wide range of phytonutrients to regulate the chemical processes prevailing in the environment. Variety of chemical products is found in leaves, fruits, and roots of plants which are basic constituent of medicines from ages. The familiar name for herbal medicine is ‘phytomedicine’. The herbal commodity market has exceeded $3.2 billion and about 32–37% of Americans use plant based products each year. It constitutes a major share and has been recognized in India as Ayurveda, Unani, Siddha, Homeopathy and Naturopathy. According to recent statistics, around 1.1 billion people (approx. 70% population) of Indians use phytonutrients as herbal products serving an alternative to allopathy. Interestingly, there has been infinite evidence of their usage in Vedas and Upanishads too. Figure  9.1 accounts the various treasures found in nature. The chapter reviews literature surveys from scopus, science direct and google scholar using keywords such as herbs, chemically modified electrode, herbs as electrochemical sensor, spices and phytochemicals for electroanalytical applications. This health protecting trait of phytochemical biomarkers has attracted the attention of scientific community and is becoming a part of latest emerging technology. Thus a new way for observational therapeutics and reverse pharmacology has also been explored in this article. The living organisms are constantly encountering oxidation and resulting in formation of byproducts (endogenous and  exogenous). Endogenous byproducts (such as transition metals, peroxides) and exogenous exposure (as UV, other higher radiations and heat) leads to the formation of reactive oxygen and nitrogen species (ROS). Few of them are hydrogen peroxide (H2O2), superoxide (O2∙-), singlet oxygen (O2∙), hydroxyl (OH−), peroxy (R[O-O]2−), and alkoxy (R-O) (Wojdyło et al. 2007) nitrogen species (NO, NO2−) which provokes countless degenerative diseases. Oxidative stress is defined as “an organisms status involving damage caused by disproportionation between oxidative and reductive factors, and even considered as an hindrance to the redox circuits in signaling and transduction pathways”. Living organisms produce strong antioxidant effect in order to reduce the harm and to counter the potent diseases. Natural antioxidant combinations can be added

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Fig. 9.1  Relates the treasure of various phytonutrients found in the nature

to food, or in the wrapping materials to fight against these ROS. There is a reverse relationship between the ingestion of plant origin foods such as fruits and vegetables and their outcomes such as oxidative & stress-related disorder confirmed by epidemiological studies. Phyto-compounds have started to gain attention because of potentially high antioxidant activity ascribed with these compounds (Rimm 1996). Natural antioxidants play a key role in radical scavenging reactions occurring in the body, which are quite similar to the reactions during the processing of polyolefin (Kirschweng et  al. 2017). Phytonutrients  can affect the immune system as either adaptogens or immune-stimulants or both. Adaptogens expand the resistance against any kind of the physical, chemical or biological agents whereas immunostimulants activate and initiates the non-specific, innate defense mechanism against pathogens. In general, bio-compound obtained from natural sources are phenolics (flavonoids or non-flavonoids) (Hidalgo et al. 2010), that are associated to health (most common such as curcumin, gingerol and so on). This review article demonstrates few of real life key problems, theories and potential applications associated with use of these phyto-phenols into the scientific arena. The electroanalysis has been extensively applied for mechanistic studies and analytical determinations of these potent chemical combinations. Thus, this article confers the state of art regarding the main application of electroanalysis based of phytonutrients. The approach of redox behavior characterization promotes a better understanding of structure, inherent assets and relationships. The electrochemical characterization is a useful approach to encounter the mechanism behind stability,

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antioxidant activity, pro-oxidant effect and other chemical structural aspects involved due to their redox behavior. Herein the goal is to summarize, analyze and focus minutiously on these phyto-­ phenolic molecules from Indian origin commonly used all over the world. Several of them are listed with their uses, electrochemical behavior and applications. Published literature however is scarce due to more focus on synthetic organic compounds rather than naturally available phytophenols. Even their analysis in this context to electrochemistry is quite limited, hence other methodologies coupled with electroanalysis has been included for better illustrations.

9.1.1  History

9.1.2  Overview of Phytochemicals Over the decade there has been immense expansion observed in the scientific field using plants as a medicine or preservative that has been obtaining tremendous popularity. Figure 9.2 account for the use of herbs in the scientific fields from 1950 till today. During the last 10 years, their usage has increased almost 20 folds. A number of phytochemicals have been used as a part of medicine in the past such as rasayan (Halliwell 2006). In India, around 2500 plant species are used in medicinal procedures as listed by the World Health Organization. India has become one of the substantial creators of medicinal products due to its diverse flora and fauna and is even regarded as the botanical garden of the world. The Greek physician Galen framed the introductory ‘pharmacopoeia’ narrating the appearance, properties and use of many plants during his time. Natural products chemistry devised with the effort of Serturner, who isolated morphine from opium (Papaver Somniferum), have been reflected in medicines since more than 5000 years. A number of plant nutrients and their usage have been listed in the Table 9.1 along with their potent benefits. The phyto-chemical system has always been parallel to pharmacology but not in the “domain of obscurity” as mentioned by Venkat Subranmaniam (Yip and Mahal 2008). Many people make use of plant products such as herbs, spices, healthy food and even in form of self-medication. Even today aged people consume curcumin in case of stomach bloating or gastric problems. It has been perceived that the phenolic plant compounds have protective effect against liver, colon and tongue carcinogenesis. Hence, these systems are not just a part of folklore or traditional practices. These have been the basic axioms of the system leading to a logical and systematic structure of pathogenesis and diagnosis. Roy Choudhary implemented Observational Therapeutics (Chaudhury and Rafei 2001), an antecedent path of Reverse Pharmacology i.e. the new drug development

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Fig. 9.2  Details of the literature relating to no. of articles published relevant to Phytochemical with respect to (wrt) Years Table 9.1  Details of few articles published by various authors in context to the phytonutrients and their corresponding electrochemical aspects Reported Literature Reviews Physico-chemical studies of the antioxidant activity of herbal extracts and active principles of some Indian medicinal plants

Aspects Viewed 1. The article illustrates the potential usage of herbal extracts especially medicinal plants using physicochemical techniques. 2. They studied ginger, curcumin, bakuchiol and established their oxidation mechanism by measuring kinetic parameters and physico-chemical properties in order to understand the radical scavenging activity.

Unclear Aspects References 1. The kinetic parameter for Adhikari et al. (2007) radical scavenging activity was determined indirectly by accounting hydroxyl radical content which can be produced by any other interfering compound/ species present in the mixture 2. Estimation of antioxidant properties without substantiate data on their mechanistic proof. 3. The redox activities and potential were kept under future goals. (continued)

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Table 9.1 (continued) Reported Literature Reviews Current Status of Herbal Drugs in India

Electrochemical Methods for total antioxidant capacity and its main contributors determination: A review

Flavinoid Electrochemistry: a review on the electro analytical applications

Aspects Viewed 1. The article explains about the importance of Herbs in the current world. 2. The emphasis is being put on the Indian Plants which too can be accommodated as a part of Observational Therapeutics and Reverse Pharmacology. 3. The research approach for different natural products has been explained extensively. 4. Emphasis has been laid primarily on their potential health benefits. 1. Background of the electrochemical methods has been explained in detail. 2. Different techniques have been elaborately explained.

Unclear Aspects References 1. The goal of the paper has Rathore et al. (2007) not accommodated the real facts observed in the world. 2. Their benefits have been stated without biological reference or supporting data.

1. The review includes the electrochemical aspect on the flavonoids present in the nature. 2. The crisp data is provided about the use of phyto-chemicals in the scientific community.

Gil and 1. Apart from flavonoids, other compounds containing Couto (2013) lignin, has not been included. 2. Theoretical aspect of redox behavior has not been detailed. 3. The A-ring chemistry of molecules emphasis was missing. 4. The relation of the antioxidant behavior and only electrochemical aspects were incorporated without any account regarding variants.

1. The electrochemical techniques have been correlated only with basic applications and still lots of other potential applications are unaccounted. 2. The correlation with real and particularly natural components is missing. 3. The paper is not able to confer a realistic approach.

Pisoschi et al. (2015a)

(continued)

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Table 9.1 (continued) Reported Literature Reviews Electrochemical Methods for the analysis of clinically relevant biomolecules

Aspects Viewed 1. The review summaries electrochemical methods in clinical analysis using numerous biomolecules. 2. Various electrochemical biosensors with numerous recognition elements are detailed. 3. The scope of polymer and even paper based micro fluid devices are highlighted. 4. Schematic illustration of scope regarding electrochemical approach for diseases diagnosis is portrayed. 1. Article briefly accounts investigation about herbs and other functional groups in safe and efficacious doses. 2. The study has analysed the antiinflammatory effect on subsequent dosage. 3. The table mentioned in this paper summarizes the active component, action and their interaction in equine research.

Unclear Aspects 1. Use of environmental degrading molecules are reported which pose a huge threat for future.

1. The investigation was performed on the horse and their relation on its consumption was assumed. 2. The herbal drug interaction was believed and no supporting mechanism or proof was delivered. 3. The toxicity studies were not performed as it could lead to ill effects on the individual. 4. The paper itself does consider the option of consultation of a veterinarian. 1. Their characterization is 1. The emphasis is on Flavonoids— not explained in context of chemistry, metabolism, flavonoids, their properties and abundance practical work. cardio-­protective in nature. effects, and dietary 2. Their positive aspects sources regarding the chelating ability and antioxidant properties are explored. 3. Possibility of taking flavonoids as an alternative therapeutic cure to heart diseases and medication purposes is observed. 4. Adverse effects are mentioned in an elaborate form upon over dosage.

Some commonly fed herbs and other functional foods in equine nutrition: A review

References Labib et al. (2016)

Williams et al. (2007)

Cook and Samman (2006)

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Aspects Viewed 1. Opens a new world of numerous herbs and their therapeutic usage. 2. Explores the possibility of using herbs in current scenario in technological advancement. 3. Uses of Electrochemical Techniques as a suitable alternative to other available techniques. 4. Minutiously explains the relevance of adding the herbs and electrochemical techniques to bring out environmental friendly, selective, fast and rather simple way to diagnose, treat and even used as various sensors.

Unclear Aspects 1. The work evolves pre-testing and fabrication into a prototype which is time consuming. 2. The stability and reproducibility of sensor is of prime importance. 3. The employment of herbs should be within the limits.

References –

initiated by Vaidya. Few of the plant based product and their usage with details about their electroactivity is mentioned in Table 9.2. These are the pathway for important source of beneficial compounds including food ingredients. They promote health, prevent illness and even act as dietary fibers, vitamins, minerals, antioxidants, essential omega 3 fatty acids, lignins, etc. In India, there is a tradition of using whole foods as functional foods rather than supplements. For instance, spices such as sesame seeds, garlic, onion, saffron and many other plant derivatives provoke high level of health-protecting biomarkers and extensively commercialized as phytopharmaceuticals, and isolated compounds i.e. rutin and diosmin as vitamins and drugs. In the early 1500’s, Indian fever bark was one of the novel medicinal plants to locate its buyers in Europe. The bark was obtained from cinchona tree and brought into light by native people of the Andes and Amazon highlands to tackle fever. In early sixteenth century, Jesuit missionaries brought it back to Europe and named as ‘Jesuit fever bark’. In Andean culture, the coca tree leaves were chewed due to its health advantages. In addition, during 1860 Koler isolated cocaine and found its potent use as a local anesthetic for eye surgery. Later researchers outlaid the consequence of cocaine usage, leading to nerve ending paralysis which is accountable for transmitting pain and loss of sensation. Furthermore, Jaborandi tree (Pilocarpus jaborandi) expels alkaloid-rich oil containing alkaloid pilocarpine, used to treat blinding disease, glaucoma. American Indians

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Table 9.2  Details of representatives of natural plant products, its scientific names and potent usage Scientific name Curcuma longa L.

Family Name Zingiberaceae

Common Electro-active name Species Curcumin Curcumin

Ocimum sanctum Linn.

Lamiaceae

Tulsi

Eugenol, Carvacrol, Estragol, Caryophylline

Foeniculum vulgare Umbelliferae mill.

Fennel

Liquorice (liguiritin)

Camellia sinesis Linn.

Theacease

Tea

Theaflavins, tannins and flavonoids.

Crocus sativus Linn.

Iridaceae

Saffron

Carotenoids, monoterpene aldehydes, picrocrocin

Curculigo orchioides

Amaryllidaceae Black Musli

Sesamum indicum

Sesamum

Sesame

Sesamol

Citrus medica Linn. Rutaceae

Lemon

Limonene

Curculigo

Uses Anti-inflammatory, anti-diabetic, improving blood circulation. Treatment of migraine, paralysis and skin diseases, ulcers and scabies, skin beautification, vitiligo and leukoderma. Protects from bronchitis, malaria, diarrhea, dysentery, skin disease, arthritis, eye diseases. It is anti-diabetic, antipyretic, insect bites, anti-fertility, anticancer, anti-diabetic, antifungal, antimicrobial, cardio-protective, analgesic, antispasmodic with adaptogenic actions. Digestive impairment, colic pain, cough, blood disorders, dysentery and hemorrhoids treatment. Aids in weight loss, has potential to lower the risk of human diseases, prevention of cancer and reduces risk of stroke. Effective against sinus, headache, nausea, cough, throat infection, pytiriasis versicolor, belching, dysuria, migraine. Prevents hemorrhoids, nervous system disorders and initiates weight loss. Protect heart health, improves blood pressure, balance hormones, fight cancer, helps in burn fat, boost nutrient absorption Treatment of bleeding disorders, dyspnea, cough, thirst, gastro intestinal disorders, constipation, alcoholism, hiccups digestive impairment. (continued)

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Table 9.2 (continued) Scientific name Glycyrrhizaglabra Linn.

Family Name Fabaceae

Eucalyptus globulus Myrtaceae Labill. and other species of Eucalyptus

Common name Mulethi

Electro-active Species Glycyrrhizin

Natural essential oils

Uses Cough, hoarseness of voice, weakness, sinus, gout treatment. Digestive impairment, rheumatism, sinusitis in children, cystitis, non-healing ulcer, chronic pyaemia, fever, cough, helminthiasis, chronic rhinitis, coryza, osteoarthritis, headache, puerperal fever, asthma, skin disease, tuberculosis medication.

used pineapple poultices to reduce inflammation of wounds and skin injuries and it even aids in digestion to ease stomachache. Bromelain, present in fresh pineapple juice breaks down proteins and blood clots. Other pharmaceuticals having their origin in botanicals include atropine, hyoscine, digoxin, colchicine and emetine. Later,  Reserpine, an anti-hypertensive alkaloid (Rauwolfia serpentina) became available as a result of investigation carried by Ciba-Geigy in India. It is relevant to note that most of early discoveries rely on traditional medicines but many products could be poisonous on excessive consumption. A major problem with traditional, indigenous medicine is discovering a reliable ‘living tradition’ rather than relying upon second-hand accounts of their value and usage. Hence, the concept of investigational studies started.

9.2  Electrochemical Aspects of Phytonutrients 9.2.1  Use of Different Electrochemical Techniques Numerous techniques have emerged in order to analyze/determine phytonutrients for their antioxidant activity, usage, nutritive value, application as a sensor and pharmacological benefits (Sakakibara et al. 2003). Every type of analysis has a specific basis. Countless literatures have reveiled their determination using coulometric detectors enabling higher sensitivity and lower noise. Reverse-Phase High Pressure Liquid Chromatography (RP-HPLC) has been utilized to determine the blood profile of person affected with Parkinson’s disease when the patient was treated with anti-Parkinson Drug. The phenols present in the blood are accounted using Folin-­ Ciocalteu assays. The spectrophotometry relies on the chemical reaction taking place between the phenols producing a total output measured at 750 nm absorbance

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correlating with concentration. The selection of standard is a tedious job due to the presence of numerous phenols in the mixture. Colorimetric or spectrophotometric investigations are dependent on the distance travelled by radiation and the turbidity of cell which changes with external factors, thus leading to wrong estimations. Among all, special attraction has been edged by the electrochemical techniques due to their improvement of research resource usage. They incorporate much advantages over present techniques due to their simplicity, fastness, inexpensive instrumentation, small volume and real sample applications based on oxidation and reduction mechanism (using electron transfer). Conventional techniques employed for the determination are quite cumbersome and uneconomical, thus requiring offline sample preparations and even results in low precision. The electrochemical profile of distinct herbs, akin to their redox behavior is driven by the phenoxy radical generation, which implies its overall reaction mechanistic pathway. It neither involves use of hazardous chemicals or temperature ranges which are quite observed in conventional techniques.

Among different electrochemical methods, coulometry and voltammetry are principle electroanalytical approaches, but techniques coupled with chromatographic or Flow Injection Analysis (FIA) systems have shown better results. The robustness of electrochemical approaches makes it a better choice. Numerous solvents and electrolytes are thus applicable for assessment providing a wide range of choice whereas in conventional techniques, a protocol is to be followed with specific solvent, temperature and pressure parameters. They assist in assessing the kinetic and mechanistic parameters (including unknown ones), supporting strong theoretical background which is quite absent in conventional techniques. Electrochemical analysis has been stipulated involving different approaches such as volammetry, biamperometry, amperometry, potentiometry and coulometry. The voltammetric skill technique is a potentio-dynamic assay based on current recording vs. potential. Thus it exploits the redox activity of the concerned molecule. They are further subdivided on the basis of resolution. The Cyclic Voltammetry (CV) provides the redox behavior of the compound, different oxidation states of molecule and its stability. The CV accounts for the analytical peaks obtained as the potential is scanned. Therefore the response potray their respective redox activity or electron transfer occurring into the bulk. It enables a relative enquiry about antioxidant capacity, inhibition activity, intermediates and adulterant concentration. The lower potentials reflect easy electron transfer ability, hence fast redox activity. It helps us understand redox process while monitoring the intermediates. Literature has accounted various advantages of voltammetric assays when compared to spectrophotometry (e.g. DPPH method) where voltammetric determination provides fast and economical method for assertion with similar

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accuracy, regardless of temperature difference with better peak separation options. CV can even be used to illustrate the correlation between action of free radical wrt vitamin supplementation, efficiency of treatment, corrosion vs. metal, disease vs. diet, etc. The reducing ability of onion flavonoids assessed by cyclic voltammetry was twice compared to the antioxidant activity given by hydrosoluble components (ACW) evaluated by photochemiluminescence, and approx. 50% better than PRTC, DPPH scavenging ability and the Fiolin-Ciocalteu reagent reducing ability. Thus, the CV yielded the best results, (CV > PRTC>TEAC) ensuring lowest antioxidant gap supplied by voltammetric assays (Zielinska et al. 2008). The CV provides data about the redox states along with the information about the kinetics of electron transfer. Pulse Methods improve the sensitivity and many forms of potential modulation, making it a better technique. The Differential pulse volatmmery (DPV) helps in quantitative determination and sensitivity of compound analysed  by determining their current signal variation. The technique gives output in form of Δi/ΔE values. Thus, the double current sampling allows quantitative study of concentrations as low as 0.05 M. Enhancement of the faradaic current leads to more appropriate determination of reaction from the mechanistic viewpoint. It avoids consideration of charging current. Vishnu et al. has published the estimation of antioxidant activity and quantitative determination using DPV for fish freshness and tea quality determination (Vishnu et al. 2017, 2018). The height of signal depends on the analyte concentration and its position correlates with the analyte type. The DPV and SWV assess lower detection limit (10−7 M) and better resolution due to minimizing charging current. Anodic Stripping Voltammetry involves concentration of metal ions on electrode surface by application of negative potential. The metals are later stripped off by applying positive potential. Square wave voltammetry (SWV) is a potential staircase sweep technique considering the current at the end of each potential change. Thus, the charging current is minimized as current is considered only when ratio of faradaic current to charging current is higher. It is highly advantageous due to its speed (fast potential scan), excellent sensitivity, lack of background signals and reproducibility with optimized signal-to-noise ratio. It has turned out to be much more sensitive than DPV (Blasco et al. 2007) and provides wide dynamic range with lower detection limit when compared to CV (O’Connor and Lowry 2012), even  its flexibility and potential change, increased resolution increment case of overlapping peaks. It has insensitivity to dissolved oxygen, thus employed in drug and biological sample analysis (Dogan-­Topal et  al. 2010). Biamperometric studies helps to exploit the mechanistic understanding of redox pairs such as Fe3+/Fe2+, I2−/I−, Fe(CN)63−/ Fe(CN)64−, etc. This technique allows the determination in biological samples and also used for determining total antioxidant capacity of foodstuffs and beverages (Tougas et al. 1985) (Milardovic et al. 2005). It was employed to investigate the antioxidant capacity of fruit juices (tea, wine (Kilmartin et  al. 2001) and coffee with GCE (Milardovic et al. 2005)) and Platinum electrodes (Pisoschi et al. 2009). Amperometry relates the generation of current at a particular potential with its redox activity and stoichiometry related to the concentration of constituents

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(Wollenberger et al. 1992) (Zhao et al. 2010) (Amatatongchai et al. 2012). A drawback was observed when antioxidant capacity was determined in complex media where biorecognition elements are involved. A flow system with amperometric detection for antioxidant capacity consisted of a bioreactor using Os-wired Horse radish peroxidase (HRP). The resulting H2O2 was monitored at −0.1  V and the obtained results were confirmed by Folin-Ciocalteu assay. Chronoamperometry relates current as a function of time after a potential step is initiated by chemical reaction. Ion-selective amperometry has scarce disadvantages like deviation from Nernst’s equation and its variation with temperature or ion activity. Potentiometry is an analytical tool correlating logarithmically the activity  of compound to its potential. It was always considered advantageous than voltammetric or amperometric assays. It gives a reproducible and rapid estimation along with high sampling rate. Coulomtery allows direct oxidation/reduction signal generated at the surface of the electrode. It accounts for complete electrolysis of analyte and quantitatively reacts with reagent (Ziyatdinova et al. 2006). The results can be determined within fraction of minutes and are easily tunable for automated analysis. It can be advantageous with unstable reagents and inexpensive instrumentation (Borges et al. 2011). On the other hand solid state electrochemistry involves mechanical immobilization of the solid at the electrode surface, making the application on a wider perspective. The quantitative determinations of compounds are associated to linear relations & Faraday’s Law control the peak currents as a result of concentration.

9.2.2  Redox Behavior and Other Study Constraints The redox behavior of different plant products are characterized based on their proton-­electron transfer mechanism in numerous pH range, defined by their structural and chemical properties, such as pka and Ks. These properties have a huge consequence on the stability of radical intermediates and its course of electrochemical reactions. Indeed, these aspects are based on structural relationships (hydroxyl substituents) (Simić et al. 2007). There is an unambiguous connection between biological activity and redox behavior. Reported electrochemical profiles are tabulated in Table 9.3. There are different ways of investigation based on peak potentials and two types of behavior are mostly observed, one and two electron oxidation (Kaur and Prabhakar 2017). It is either electrochemical oxidation of phenol & resorcinol (1e−) or catechol & hydroquinone (2e−). The former is an irreversible process, furnishing in a single step while the latter is a reversible reaction leading to more number of steps. Phenol is oxidized in one electron-one proton step to phenoxy radical which is thermodynamically unstable and hence co-exists in three isomeric forms as ortho- > para- > meta position. The reversibility of EC process can be accompanied by square wave voltammetry techniques. Besides the mono and di-phenol, gallactocatechol moieties are also observed. Such patterns reflect the presence of third oxidisable hydroxyl group seen in myricetin & catechins. On the biological viewpoint, these redox donors leads to

Table 9.3  illustrates the electrochemical profiles of different analyte and significance of techniques reported Analyte Liquorice

Significance Quantification Analysis

Apple

Electrode COOH-­ Graphene Ag/AgCl

Antioxidants

Platinum

Fruit extracts

GCE

Simple, promising and direct detection in real sample Flavinoid quantification studies

Herbal extracts

dsDNA- carbon paste electrode

Chrysin, quercetin

Boron-doped diamond SPCE

Glucose extracted from Naural Fruits Edible Herbs

GCE

Use of Apple as a memristors

Based on scan rate, deposition potential and time variance in complicated matrices Metal – Fe chelating ability

Reference Wang et al. (2016) Volkov et al. (2016) Shpigun et al. (2006) Gomes et al. (2016) Skeva and Girousi (2012)

Porfírio et al. (2014) Origami paper device and elimination Liang et al. of interferents (2017) Electron Shuttering Capability was Chen et al. estimated (2017)

Table 9.4  Accounts for the numerous herbs evaluated using electrochemical techniques Technique Cyclic Voltammetry( bio-electronic tongue)

Cyclic Voltammetry Cyclic Voltammetry Amperometry (flow injection) Amperometric i-t

Square Wave Voltammetry Square Wave Voltammetry

Electrode used Tyrosinase/laccase and copper nanoparticles modified epoxy-graphite GCE-Mesoporous carbon GCE GCE@CNT Au/MWCNT@ PANI-NED

Analysed Material References Wine spiked Cetó et al. (2012) sample

Ginger

Amreen et al. (2017)

Onions Thai vegetables/ herbs Fruit Juice

Zielinska et al. (2008) Amatatongchai et al. (2012) ([CSL STYLE ERROR: reference with no printed form.]) Kamel et al. (2008)

GCE@Nucleotide

Flavoured Water Stawberries, Raspberries and Blackberries Juice, Tea, Wine

Voltammetry and Chronoamperometry

GCE@Spectral grade paraffin integrated graphite Integrated Micro-electrode Boron doped Diamond electrode

Potentiometry

Platinum

Potentiometry, LSW,DPV Polarography

GCE@Iodine

Biamperometry

Dropping Mercury Electrode

Free Flavinoids and Fe2+ Flavinoid complexes Aqueous Plant Extract Wine solution Honey Samples

Komorsky-Lovrić and Novak (2011) Milardovic et al. (2007) Porfírio et al. (2014)

Brainina et al. (2011) Castaignède et al. (2003) Muruke (2014)

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Fig. 9.3  Accounts for increasing trend of different literature published relevant to plant based electrochemical studies from 1960 till 2018

a facile electron transfer assisting other reactions and themselves act as transducers, resulting in a greener way of carrying out reactions. They can help in H-atom transfer thereby scavenging radicals, terminating chain reactions and biological reactions. The radical scavenging activity and reducing power is dependent on the electron transfer behavior of these chemicals. Hence, the activity is driven by electron donor ability marked by their Epa (potential) and ipa (current intensity). The Epa corresponds to the ability of the molecule to donate electron whilst the ipa corresponds to number of transferred electrons (YANG et al. 2001). Figure 9.3 accounts for the year wise increment in the electrochemical sensors being reported thus establishing the upcoming trend in the scientific world. The ring chemistry has been involved in assessing the redox properties of the phytophenols, where the hydroxyl groups are unambiguously pivot in determining their biological role and functions exhibiting in our body. There is always a non-­ active component navigating the redox activity of the molecule. This influence has been expressed in terms of electronic and steric effects, which might have substantial effect on its solubility and diffusion properties. The oxidation potential is increased or shifted to positive side when the substituent (amino, iodo, bromide, methoxy) as seen in Hammett’s constants are electron withdrawing groups which hampers electron loss, while electron-donor substituent reduces peak oxidation potentials. The presence of double bond and hydroxyl groups enhances the electron donating ability and thus lowers the expected potential (Simić et al. 2007). Peak potentials are shifted to the positive side if hydroxyl hydration is decreased while hydrophilic substituents enhance the proton transfer ability and antioxidant activity in aqueous media. The hydrophilic contribution and non-oxidizable substituents lead to over potential. Easier deprotonation and decrease in peak potential is reflected as pH increase in electrolyte solution. The electrode material,

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Fig. 9.4  Stepwise illustration the  fabrication of nanomaterial based electrochemical biosensor with immobilized biomolecules. (Reprinted with permissions from ref (Kaur and Prabhakar 2017). Copyright 2018)

concentration of electro-active species and the technique are a major contributing factor in peak shift, whereas temperature and pressure have minor impacts. The cell used in routine  electrochemical analysis is a either a two or  three electrode system, preferable three electrode setup where potential is relative to the reference electrode (commonly used  Pt) and working electrode (usually  GCE  or chemically modified electrode). The current is measured between the working and a counter electrode (commonly used  Ag/AgCl). The tips of electrodes must be placed in close proximity to the working electrode in order to reduce resistance due to the bulk of the solution. All the experiments are preceded in room temperature. The supported electrolyte can be a buffer or organic solvent. A huge number of distinct varieties of working electrode materials are being explored these days. The stock solutions of compound are prepared using ethanol, methanol, water, NaOH or even a mixture of different electrolytes. During the years, new developments in field of electrochemical sensors are being enriched via nanotechnology (Guo and Wang 2007). One of such development is involvement and fabrication of biosensors as reported in Fig. 9.4. Nano sized materials not just accomplish performance enhancing factors (such as  sensitivity, response time, LOD etc.) but also escalate its fabrication process. An appropriate nanomaterial comprises of fundamental attributes such as ease of preparation, availability and presence of adjoining groups, higher stability and lower reactivity when compared to a better matrix during fabrication. Their presence accounts for

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Fig. 9.5  Cartoonistic illustration of the importance of ring structures and the effect of hydroxy group in different molecules contributing to their redox-active characetristics and their biological significance. Few of the noted moeities in A, B and C are accounted. (a) Ortho-dioxy structure in ring B, like catechol in A (b) 2–3 double bond in conjugation with 4-oxo functional group in B (c) Hydroxyl group at position 3 and 5 provides hydrogen bonding in C

enhancing the surface area and helps in better  immobilization of compound with faster kinetics for reaction process. Numerous varieties of matrix accounted for sensing are available in market such as screen printed carbon electrodes (SPCEs), quantum dots (QDs), different allotropes of carbon nanomaterial (NPs, fullerenes) (Mauter et al. 2008), polymers (Rassaei et al. 2011). They have different important characteristics such as vivid binding ability, surface to volume ratio, small size that further improves the performance and stability concerns  sensors  with better precision. Apart from the analysis point of view, some other important constraints is to obtain the targeted chemical from the plant source. In order to analyse or apply the phytochemicals in the domain of food, pharmaceutical and scientific areas. Their basic understanding of isolation, fractionation and purification strategies in concentrated form of bioactive/major nutrient molecule present in the raw material are highly  needed. “Extraction efficiency (EE) is defined as the percentage of solute moving into the extraction phase.” It tends to be a function of major variable conditions such as solvent type, temperature, solvent to feed ratio, contact time, particle size, etc. Different promising techniques are assessed for extraction, isolation and separation to yield the desired phytochemical. The primary focus is to optimize the extraction of active molecules and further understanding of their characterization and detection via electrochemical pathway. Before extraction, compounds must be collected, reserved and prepared appropriately. Numerous techniques are used to extract such as Soxhlet Extract, sonication, maceretion/percolation, microwave assisted extraction, supercritical fluid (carbon dioxide) extraction, etc. Next step for Chemoprofiling is to isolate the focused molecule using any of the basic Column chromatography, High pressure liquid chromatography (HPLC), Vacuum chromatography, Thin Layer Chromatography techniques, etc. In order to remove trace contaminants and render presence of unwanted impurities in the extract, purification is the final step. Commonly HPLC, Counter current chromatography (CCC) are generally employed with a multi-phase solvent system to obtain a purity ~90%.

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9.2.3  Antioxidant and Pro-Oxidant Compounds Anti-oxidation phenomenon is a basic concept in life of an individual. Anti-oxidants delays or prevent oxidation only if it is present in lower concentration than the substrate. They can be synthesized in-vivo or taken as supplements. The reason for the ability of plants to have antioxidant potential is its powerhouses (particularly mitochondria, chloroplast) and ROS which are linked to the fine balance maintenance. ROS is generated within the plants at Photosystem (I and II) of chloroplast, membrane and matrix of peroxisomes. There is an electron slippage, which further reacts with oxygen moiety to produce superoxide. In continuation, these form hydroperoxyl radical and finally convert to hydrogen peroxide. Similarly, reactive nitrogen (RNS) and sulfur (RSS) species are reported. Mostly the production of these free radicals is genetic, as they are a function of signaling molecules. Yet there overproduction leads to damage of the balance and provokes diseases. In response to these stimulants, plants produce low and high molecular weight secondary metabolites to provide resistance. As these chain reactions are common in plants and animals, these antioxidants are equally beneficial to them. Basic example is ascorbic acid (vitamin C) which helps in termination of these reactions. The antioxidant effect can be correlated to the ring structure of the molecule. The main feature responsible is the presence of hydroxyl group on the phenolic ring. The hydroxyl group helps in donation of ‘H’ hydrogen atom, thereby inhibiting the oxidation process and finally forming hydroperoxide (ROOH). The presence of more than one group further increases the rate especially where secondary hydroxyl group is present. Furthermore, the alkyl chains connecting the phenolic ring to alcoholic or carboxylic group are few important phenolic rings that stabilize phenoxy radicals (ArO). Other important characteristics are: ortho-dihydroxy catechol structure in B ring for electron delocalization, 2–3 double bond in conjugation with 4-oxo function in ring C for efficient electron delocalization in ring B while hydroxyl group at position 3 and 5 provides hydrogen bonding to oxo group as shown in Fig. 9.5. The corresponding are few of the minute details corresponding to Fig. 9.5: (a) Ortho-dioxy structure in ring B, like catechol in A. (b) 2–3 double bond in conjugation with 4-oxo functional group in B. (c) Hydroxyl group at position 3 and 5 provides hydrogen bonding in C. Antioxidants are generally  reducing agents which  are termed as pro-oxidants. The pro-oxidants promote oxidation of compounds and are dependent on hydroxyl groups in the moiety (especially in ring B), leading to production of hydroxyl radical. Compounds with a pyrogallol structure in ring A promote hydrogen peroxide production while 2–3 double bond and 4-oxo arrangement promotes ROS. Epigallocatechin gallate promotes apoptosis and induces bactericidal activity, thus reduces O2 to H2O2. These further induce DNA strand breakage dependent on concentration. Pro-oxidant effect can too be beneficial, by imposing a mild degree of oxidative stress thus increasing the level of antioxidant behavior of molecules and therefore

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Fig. 9.6  Illustrates the use of herbs in diverse fields and their related usage as a sensor

ensuring cyto-protection. Vitamin C or Ascorbic Acid has antioxidant activity which reduces hydrogen peroxide  (which is a common byproduct of all the biological oxidase based systems), whereas on the other hand it can reduce the metal ions through fenton reactions. Important pro-oxidants in the body are uric acid, sulfhydryl amino acids, etc. The uric acid acts as a potential pro-oxidant in case of atherosclerosis and ischemic stroke. Different conventional methods are employed for determination of antioxidant activities such as ferric reducing antioxidant power (FRAP), copper reduction assay, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, ABTS assay, etc. based on either hydrogen atom transfer or single electron transfer mechanism. The Antioxidant or Pro-oxidant effect can be accounted using electrochemical techniques such as Cyclic Voltammetry. CV involves the scanning of voltage and current which is directly proportional to the concentration of antioxidants. Born et al. had analysed the antioxidant potential of compounds and deduced some observations wherein compounds having a catechol moiety (meta position) in their structure were oxidized below 0.4  V.  Molecules containing phenolic groups as isolated form were oxidized between 0.45 V to 0.8 V (Sochor et al. 2013). The compounds with lower oxidation potential Epa  0.45 V showed pro-oxidant behavior. The area under the anodic wave and particular potential helped in further determining the structural parameters such as bond dissociation enthalpy and ionization potential. Biamperometry has also been used to measure the antioxidant determination by DPPH assay. The current intensity is directly

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proportional to residual DPPH after reaction with antioxidant. Later a report accounts the testing for different varieties of tea, coffee, juices using electrochemical approach (Milardovi 2005). Parameters accounting the antioxidant capacity are Ep(peak potential), current density(ip), and charge (Q) for both waves wherein the experimental CV data has to be related to a standard, to ensure consistency of results.

9.3  D  evelopments in Field of Electro-Profiling of Phytochemicals and Suitability in Real Life Stipulations based on herbs have been on demand in order to provide better treatment of health problems due to their natural occurrence and ecological sustainability. The topic of Indian herbs has always been daunting for a new entract to the field. Interesting and novel activities supported by herbs have been exploited by CSIR to formulate drugs for anti-diabetic, anti-arthritis and treatment of hepatitis (Patwardhan and Khambholja 2009). Even academia, non-profitable and governmental institutes are governing research for the aforesaid in order to make a better future. Few of the prominent reported plant based medicines are betulinic acid, camptothecin, topotecan (Hycamtin®), CPT-11 (irinotecan, Camptosar®), 9-aminocamptothecin, beta, podophyllotoxin, etoposide, podophyllinic acid, vinblastine (Velban®), vincristine (leurocristine, Oncovin®), vindesine (Eldisine®, Fildesin®), docetaxel (Taxotere®), paclitaxel (Taxol®), tubocurarine and pilocarpine. There are always references of historical documents regarding the trade of Indian plants and spices, even during the Mesopotamian times (Bedigian 2004). Most recent assays include the study of health benefits of medicinal plants, spices and their chemical constituents. Few of the diverse field of applications using herbs is illustrated in Fig. 9.6. The cyclic voltammetric studies helps in proving presence of various phenolic groups present in wine, tea, curcumin, gingerol, sesamol and their characterization by reducing strength and oxidation reversibility studies (Ali et al. 2008). Polyphenol oxidation to quinone yields an anodic peak in the positive potentials and reduction of quinone yields a cathodic peak during the second potential scan sweep. Few herbs contain phenolic acids and flavonoids with ortho diphenol group present such as caffeic acid, catechin, epichatechin, sesamol which are endowed with high antioxidant properties. Other herbs containing phenols with greater potentials enables smaller antioxidant and lower reducing ability, thus do not constitute ortho-diphenol structure (ferulic acid, vanillic, p-coumaric acid). Anthocyanins present in red wine are the group of antioxidants corresponding to redox peak observed at 0.65  V, referring to its difficulty in oxidisable groups at higher potential. Each phenolic peak represent (anodic) depending on the –OH group attached to the structure which get oxidized. Catechin and epicatechin represents meta-diphenol groups present in the A-ring, gallic acid is due to the virtue of

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Fig. 9.7  Principle of biosensors based on different biomolecules aimed for OPs detection. (Reprinted with permissions from ref. (Kaur and Prabhakar 2017). Copyright 2018)

its third –OH group, quercetin owns due to the hydroxyl group present on B-ring, Sesamol portrays due to the virtue of its hydroxyl group present at orthodiphenol structure (Kilmartin et al. 2001). Second redox peak is also observed sometimes at higher oxidation potentials (Castaignède et al. 2003). The white wine shows peaks at 0.48 V and 0.95 V where the first and second peak demonstrates catechol containing hydroxyl-cinnamic acid and polyphenols respectively. Simmilarly, India aloe has also been a major constituent of cosmetics, medicinal, in nutraceutical purposes and its electrochemical aspects. The herbs contain phenols as the major group imparting redox behavior as in chlorogenic acid, cordigol, cordigone, danthrone, 1,5-dihydroxy-3- methoxyxanthone, eriosematin, flemichin D, frutinone A, mangiferin, quercetin, 1,3,6,7- tetrahydroxyxanthone and verbascoside. The analysis dealt with study of compounds, where catechol groups (meta arrangement) were oxidized below 0.4  V, whereas others containing isolated phenolic group were oxidized between 0.45 to 0.8 V. Apart from rest, 1,5- dihydroxy-3-methoxyxanthone (0.45  V), danthrone (0.96  V) and eriosematin, showed no antioxidant activity. Sinic et al. has reported the connection observed between antioxidant property and capacity using numerous examples such as salicylic acid, meta and para-hydroxybenzoic acid, p-hydroxybenzoic acid, ortho, meta and para-coumaric acid, caffeic acid and rutin. They inferred that low oxidation potential compounds illustrated high antioxidant capacity and activity (Simić et al. 2007). The viability of numerous electrochemical techniques has been confirmed due to these analytical characteristics obtained during numerous applications in fields

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especially food, health, clinic and pharmaceutical analysis. It is even stipulated that smokers who ingest herbs are partly protected from harmful effects due to the characteristics of antioxidants and flavonoids presence that fight with the carcinogens within their mucosal cells (Cook and Samman 2006).

9.4  Challenges Literature has already postulated and proved the benefits for the  usage of phytochemicals but its accessibility is a major constraint due to linguistic barrier. There has been huge errors encountered while translating it in different languages. CSIR has already started a major effect for digitalizing traditional Ayurveda knowledge library (TKDL) (Rathore et  al. 2007). Major hindrance observed in amalgamation of plant based medicines in modern practice is due to the lack of scientific and clinic knowledge providing the efficacy and safety. These contain a lot of bio-­combinations which might be disadvantageous in the view of drug synthesis. They do not have a unique molecule rather contains numerous compounds in minute quantities which creates a hindrance in its selection. The developer of penicillin had written an article stating ‘The quest for new biodynamic substances’. He wrote that there cannot be much light in view of future related to surprises from South Asia especially India and China regarding study of plants having interesting pharmacological activities. His overview came in 1967 and has not yet been established wrong. Herbal medicines are still under the domain of ‘old wives’ tales’ and quack medicine, exploitation of the sick, the desperate and the gullible. Sadly, herbal medicines continued to have poor quality control both for materials and clinical efficacy. Voltammetric or Electrochemical Techniques have reflected numerous limitations. The voltammetric estimation regarding quantitative determination is not always true  and needs proper controls. The oxidation potential of the transducer observed at the electrode surface is not just due to the electrode but is related to the dependence on the reaction mechanism occurring at the Helmholtz’s Double Layer (Pisoschi et al. 2015b). One of the pictorial biosensor based on OP detection is shown in Fig. 9.7. Cyclic Voltammetry with reliable results are accompanied with poor sensitivity and detection limit when compared with pulse techniques (Settle 1997). Many a times, the bare GCE is used directly to determine the antiradical power while estimating the behavior of phenolic acids, which is later parallely confirmed by DPPH method (Magarelli et al. 2013). This is a concern as usually, a minimum quantity of the compound is required to obtain results known as ‘Limit of Detection’ below which the technique becomes incompatible to draw results as the charging current confines its value for the extent of quantitative measurements. There is always a ‘range’ above which the response becomes saturated depending on the type of electrode being used. Hence, proper controls for the detection limit and range has to be monitored in advance before accounting any such estimation studies (antioxidant

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activity, catalysis, sensing, etc.). Moreover, the delayed analysis can create a ­hindrance or false response. During the performance of voltammetric experiments, it was observed that storage of unstable phenolic compounds result in browning and contributes to secondary peaks at higher oxidation potentials. In CV, small discrepancies on peak potential values are observed (Bortolomeazzi et al. 2007) due to change in experimental conditions (concentration, pH, scan rate, temperature). Very high pH implies dissociation of weak acidic groups present. Even the intensities of the voltammograms are observed to increase as the scan rate increases. A higher scan rate leads to a higher sensibility, but pushing the charging current to higher value leads to shift in oxidation signals to higher potentials. Moreover high scan rates can lead to distorted peaks as oxidation peak current is dependent on logarithm of scan rate, where close value of 0.5 observes a diffusion-­ controlled process regulating the reaction. Even increment in pH leads to the shift towards lower potential or less positive value and hence its oxidation becomes easier. The major flaw in case of electrochemical sensors, is their discrimination among the molecules and reusability in case of few molecules that once oxidized are never reduced again (guanine base), making it a disposable sensor. Even though that biomolecules have been immobilized, certain imperfections are observed such as controlling the size and position, non-specific adsorption and poor reproducibility (Jing and Reichert 2017).

9.5  Future Aspects and Recommendations There has always been a quest for new clinical implication of traditionally used medicinal plants (Patwardhan et  al. 2004). Many drugs can be formulated using Indian herbs as they are natural and pose very few side effects. ‘Syndrex’ a drug developed by Plethico Laboratory contains extracts of fenugreek seeds (Rathore et al. 2007) which is used to cure Diabetes. Few drugs formulated by plant products and their derivatives are used by the pharmaceutical industry are paclitaxel, vincristine, vinblastine, artemisinin, camptothecin and podophyllotoxin (Patwardhan et al. 2004). India has adopted the method of Reverse Pharmacology and the golden triangle which correlates R& D network keeping in consideration the modern medicine, Indian system of medicine, and life and pharmaceutical sciences (Sharma et al. 2014). Numerous research is being conducted for the incorporation of natural antioxidants into polymers in order to suppress the usage of other chemical additive as stabilizers which cause harm to the environment and the living beings (F 2017). Besides just expanding the field of synthetic therapeutics and preventive armamentarium, new pharmacores based on natural herbs have to be evolved with time providing an increment towards combinatorial chemistry; e.g. curcumin which is quite economical and a basic constituent diet in Indian house having a target molecule for a large number of combinatorial compounds. Herb-based formulations for treating diseases have been made by Council of Scientific and Industrial Research (CSIR). There is a need for International collaboration in order to explore, track and

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analyze the clinical observations regarding their use. Lag phase in botanical medicine is now rapidly evolving to a steady state due to number of issues. New problems are encountered regarding drug-resistant microorganisms, side effects and emerging diseases having no suitable medication available. It has stimulated renewed interest in phytonutrients. Scientists have reported new compounds having neuro-protective properties such as N-methyl D-aspartic acid receptor antagonists having antioxidant properties. The electrochemical analysis of compound has been evaluated using CV where the radical-scavenging properties were compared using standard biological assays, inhibition of lipid peroxidation and the Sapphire colorimetric assay. The antioxidant activity has been due to hydroxyl and amino substituents present in the herbs (Sochor et al. 2013). A holistic approach is a need for the customization of herbs and thus electrochemical analysis. Many pharmaceutical organizations such as Dabur, Zandu, Arya Vaidya, Nicholas Piramal and Ranbaxy have launched new projects. The Pharmaceutical Research and Development Committee (PRDC) Report of the Ministry of Chemicals, Government of India has highlighted the value and benefits of traditional knowledge. Upcoming electrochemical sensors are based on 3D printing, which have allowed researchers to further design simple, flexible, sensitive and cost-effective device on small scales. Inkjet printing has accomplished the deposition of biomolecules and nanomaterial directly from the printing machine. Mainly thermal and piezoelectric inkjet printings are the future of sensors. Many portable systems with smartphone camera and wireless technology open a new outlook in the field of point of care (POC) diagnostic applications(Fontanesi). Owing to the properties of smartphone based biosensors, scientists minimized the device size, reduced the cost and simplified the principle of wireless sensors for the detection of various target compounds. These biosensors could be used as a screen display, data analyzer and signal detector due to its advanced computing capabilities.

9.6  Conclusion The consensuses of plants vs. synthetic analogues are tremendously increasing day by day and the general public do prefer natural and green products over synthetic compositions. Traditional knowledge imply powerful search engine and facilitates safe research practices, thus accelerating and improving the innovation in drug target elucidation. In India itself, 70% of the population use herbal components as a drug to cure their health related problems. A number of institutes are carrying out research on herbs, by using ‘reverse pharmacological approach’ and accelerating the progress toward accepting herbs as an alternative. Few examples are Wolfia Alkaloids in case of hypertension, holarrhena alkaloids in amoebiasis, mucuna pruriens for Parkinson’s disease, baccosides in mental retention, picrosides for hepatic protection, phyllanthins an alternative to antivirals, curcumin during inflammation, and many other steroidal lactones and glycosides as immune-modulators (Freed

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et al. 1976). The Research & Development thrust in pharmaceutical industry has shifted their focus on development of phytomedicine and there examination with a facile, robust and economical technique which is non-invasive too. The electrochemical techniques have extensively influenced the way of investigation owing to its redox mechanism platform. When conventional techniques are equated, electrochemical sensors are the greatest assets of simplicity, sensitivity, cost-effectiveness and rapid detection. They have become the today’s most suitable biochemical analysis technique reasonably due to its good detection limit, reliability, less sample requirement and less bulky instrumentations involvement, hence chosen as a competent alternative. But still research should be focused for further expansion of all round applications. Acknowledgement  The authors would like to acknowledge the research guides for their support. Mansi Gandhi  would like to appreciate the Fellowship funded by Ministry of Science and Technology(MOST), Taiwan, Republic of China(ROC), Institute of Environmental Engineering and Management; and National Taipei University of Technology under grant number 104-2221-E-027-004-MY3.

References Adhikari S, Priyadarsini KI, Mukherjee T (2007) Recent advances in Indian Herbal Drug Research Guest Editor : Thomas Paul Asir Devasagayam Physico-Chemical Studies on the Evaluation of the Antioxidant Activity of Herbal Extracts and Active Principles of Some Indian Medicinal Plants, pp 174–183 Ali SS, Kasoju N, Luthra A, et al (2008) Indian medicinal herbs as sources of antioxidants. Food Res Int 41:1–15. https://doi.org/10.1016/j.foodres.2007.10.001 Amatatongchai M, Laosing S, Chailapakul O, Nacapricha D (2012) Simple flow injection for screening of total antioxidant capacity by amperometric detection of DPPH radical on carbon nanotube modified-glassy carbon electrode. Talanta 97:267–272. https://doi.org/10.1016/j. talanta.2012.04.029 Amreen K, Shukla VK, Shukla S, et  al (2017) Redox behaviour and surface-confinement of electro active species of ginger extract on graphitized mesoporous carbon surface and its copper complex for H2 O2 sensing. Nano-Structures Nano-Objects 11:56–64. https://doi. org/10.1016/j.nanoso.2017.06.004 Bedigian D (2004) History and lore of esame in Southwest Asia. Econ Bot 58:329–353 Blasco AJ, González Crevillén A, González MC, Escarpa A (2007) Direct electrochemical sensing and detection of natural antioxidants and antioxidant capacity in vitro systems. Electroanalysis 19:2275–2286. https://doi.org/10.1002/elan.200704004 Borges PP, Sobral SP, Da Silva L et al (2011) Constant-current coulometry and ion chromatography bromide determination to characterize the purity of the potassium chloride. J Braz Chem Soc 22:1931–1938. https://doi.org/10.1590/S0103-­50532011001000014 Bortolomeazzi R, Sebastianutto N, Toniolo R, Pizzariello A (2007) Comparative evaluation of the antioxidant capacity of smoke flavouring phenols by crocin bleaching inhibition, DPPH radical scavenging and oxidation potential. Food Chem 100:1481–1489. https://doi.org/10.1016/j. foodchem.2005.11.039 Brainina KZ, Gerasimova EL, Kasaikina OT, Ivanova AV (2011) Antioxidant activity evaluation assay based on peroxide radicals generation and potentiometric measurement. Anal Lett 44:1405–1415. https://doi.org/10.1080/00032719.2010.512687

336

M. Gandhi et al.

Castaignède V, Durliat H, Comtat M (2003) Amperometric and potentiometric determination of catechin as model of polyphenols in wines. Anal Lett 36:1707–1720. https://doi.org/10.1081/ AL-­120023610 Cetó X, Céspedes F, Pividori MI et  al (2012) Resolution of phenolic antioxidant mixtures employing a voltammetric bio-electronic tongue. Analyst 137:349–356. https://doi. org/10.1039/C1AN15456G Chaudhury R, Rafei U (2001) Traditional medicine in Asia. … South-East Asia, New Delhi, SEARO … 23 Chen B, Ma C, Liao J, et al (2017) Journal of the Taiwan Institute of Chemical Engineers Feasibility study on biostimulation of electron transfer characteristics by edible herbs-extracts. J Taiwan Inst Chem Eng 79:125–133. https://doi.org/10.1016/j.jtice.2017.04.024 Cook NC, Samman S (2006) Flavonoids-chemistry, metabolism, cardioprotective effects and dietary sources. J Nutr Biochem 7(1996):66–76. https://doi.org/10.1016/0955-­2863(95)00168-­9 Dogan-Topal B, Ozkan SA, Uslu B (2010) The analytical applications of square wave voltammetry on pharmaceutical analysis. Open Chem Biomed Methods J 3:56–73. https://doi. org/10.2174/1875038901003010056 Fontanesi C. Spin-dependent electrochemistry: a novel paradigm. Curr Opin Electrochem 7:36–41. https://doi.org/10.1016/j.coelec.2017.09.028 Freed VH, Haque R, Schmedding D, Kohnert R (1976) Physicochemical properties of some organophosphates in relation to their chronic toxicity. Environ Health Perspect 13:77–81 Gil ES, Couto RO (2013) Flavonoid electrochemistry: a review on the electroanalytical applications. Rev Bras Farmacogn  – Braz J Pharm 23:542–558. https://doi.org/10.1590/ S0102-­695X2013005000031 Gomes SMC, Ghica M, Araujo I et  al (2016) Talanta flavonoids electrochemical detection in fruit extracts and total antioxidant capacity evaluation. Talanta 154:284–291. https://doi. org/10.1016/j.talanta.2016.03.083 Guo S, Wang E (2007) Synthesis and electrochemical applications of gold nanoparticles. Anal Chim Acta 598:181–192. https://doi.org/10.1016/j.aca.2007.07.054 Halliwell B (2006) Reactive species and antioxidants. Redox biology is a fundamental theme of aerobic life. Plant Physiol 141:312–322. https://doi.org/10.1104/pp.106.077073 Hidalgo M, Sánchez-Moreno C, de Pascual-Teresa S (2010) Flavonoid-flavonoid interaction and its effect on their antioxidant activity. Food Chem 121:691–696. https://doi.org/10.1016/j. foodchem.2009.12.097 Jing C, Reichert J (2017) Nanoscale electrochemistry in the “dark-field.” https://doi.org/10.1016/j. coelec.2017.06.008 Kamel AH, Moreira FTC, Delerue-Matos C, Sales MGF (2008) Electrochemical determination of antioxidant capacities in flavored waters by guanine and adenine biosensors. Biosens Bioelectron 24:591–599. https://doi.org/10.1016/j.bios.2008.06.007 Kaur N, Prabhakar N (2017) Trends in analytical chemistry current scenario in organophosphates detection using electrochemical biosensors. Trends Anal Chem 92:62–85. https://doi. org/10.1016/j.trac.2017.04.012 Kilmartin PA, Zou H, Waterhouse AL (2001) A cyclic voltammetry method suitable for characterizing antioxidant properties of wine and wine phenolics. J Agric Food Chem 49:1957–1965. https://doi.org/10.1021/jf001044u Kirschweng B, Tátraaljai D,  Földes E, Pukánszky B (2017)  Natural antioxidants as stabilizers for polymers.  Polym Degrad Stab 145:25–40.  https://doi.org/10.1016/j.polymdegrads tab.2017.07.012 Komorsky-Lovrić Š, Novak I (2011) Determination of ellagic acid in strawberries, raspberries and blackberries by square-wave voltammetry. Int J Electrochem Sci 6:4638–4647 Labib M, Sargent EH, Kelley SO (2016) Electrochemical methods for the analysis of clinically relevant biomolecules. https://doi.org/10.1021/acs.chemrev.6b00220 Liang B, Zhu Q, Fang L et al (2017) Electrochemistry communications an origami paper device for complete elimination of interferents in enzymatic electrochemical biosensors. Electrochem Commun 82:43–46. https://doi.org/10.1016/j.elecom.2017.07.001

9  Phyto-Nanosensors: Advancement of Phytochemicals as an Electrochemical…

337

Magarelli G, da Silva JG, de Sousa Filho IA et  al (2013) Development and validation of a voltammetric method for determination of total phenolic acids in cotton cultivars. Microchem J 109:23–28. https://doi.org/10.1016/j.microc.2012.05.014 Mauter MS, Elimelech M (2008) Environmental applications of carbon-based nanomaterials. Environ Sci Technol 42:5843–5859 Milardovi S (2005) Use of DPPH · / DPPH redox couple for biamperometric determination of antioxidant activity. https://doi.org/10.1002/elan.200503312 Milardovic S, Iveković D, Rumenjak V, Grabarić BS (2005) Use of DPPH•|DPPH redox couple for biamperometric determination of antioxidant activity. Electroanalysis 17:1847–1853. https:// doi.org/10.1002/elan.200503312 Milardovic S, Kereković I, Derrico R, Rumenjak V (2007) A novel method for flow injection analysis of total antioxidant capacity using enzymatically produced ABTS*+ and biamperometric detector containing interdigitated electrode. Talanta 71:213–220. https://doi. org/10.1016/j.talanta.2006.03.042 Muruke MH (2014) Assessment of antioxidant properties of honeys from Tanzania. J Biol Agri Healthcare 4:22–33. ISSN 2224–3208 O’Connor JJ, Lowry JP (2012) A comparison of the effects of the dopamine partial agonists aripiprazole and (−)-3-PPP with quinpirole on stimulated dopamine release in the rat striatum: studies using fast cyclic voltammetry in  vitro. Eur J Pharmacol 686:60–65. https://doi. org/10.1016/j.ejphar.2012.04.046 Patwardhan B, Khambholja K (2009) Drug discovery and Ayurveda: win-win relationship between contemporary and ancient sciences. Drug Discov Dev – Present Futur Patwardhan B, Vaidya ADB, Chorghade M (2004) Ayurveda and natural products drug discovery. Curr Sci 86:789–799 Pisoschi AM, Cheregi MC, Danet AF (2009) Total antioxidant capacity of some commercial fruit juices: electrochemical and spectrophotometrical approaches. Molecules 14:480–493. https:// doi.org/10.3390/molecules14010480 Pisoschi AM, Cimpeanu C, Predoi G (2015a) Electrochemical methods for total antioxidant capacity and its main contributors determination: a review. Open Chem 824–856. https://doi. org/10.1515/chem-­2015-­0099 Pisoschi AM, Cimpeanu C, Predoi G (2015b) Electrochemical methods for total antioxidant capacity and its main contributors determination: a review. Open Chem 13:824–856. https:// doi.org/10.1515/chem-­2015-­0099 Porfírio DA, Ferreira RDQ, Malagutti AR, Valle EMA (2014) Electrochemical study of the increased antioxidant capacity of flavonoids through complexation with iron(II) ions. Electrochim Acta 141:33–38. https://doi.org/10.1016/j.electacta.2014.07.046 Rassaei L, Marken F, Sillanpää M et  al (2011) Nanoparticles in electrochemical sensors for environmental monitoring. TrAC – Trends Anal Chem 30:1704–1715. https://doi.org/10.1016/j. trac.2011.05.009 Rathore B, Ali Mahdi A, Paul BN, Saxena PN, Das SK (2007) Recent advances in Indian herbal drug research guest editor: Thomas Paul Asir Devasagayam Indian herbal medicines: possible potent therapeutic agents for Rheumatoid Arthritis. J Clin Biochem Nutr 41:12–17 Rimm EB (1996) Vegetable, fruit, and cereal fiber intake and risk of coronary heart disease among men. JAMA J Am Med Assoc 275:447–451. https://doi.org/10.1001/jama.275.6.447 Sakakibara H, Honda Y, Nakagawa S et al (2003) Simultaneous determination of all polyphenols in vegetables, fruits, and teas. J Agric Food Chem 51:571–581. https://doi.org/10.1021/jf020926l Settle FA (1997) Handbook of instrumental techniques for analytical chemistry. Prentice Hall PTR, Up Saddle River Sharma C, Singhi M, Singh C, Dam PK (2014) Applicability of reverse pharmacology for the Antimalarial Ayurveda herbal drug development: an overview, vol 4. pp 250–265 Shpigun LK, Arharova MA, Brainina KZ, Ivanova AV (2006) Flow injection potentiometric determination of total antioxidant activity of plant extracts. Anal Chim Acta 573–574:419–426. https://doi.org/10.1016/j.aca.2006.03.094

338

M. Gandhi et al.

Simić A, Manojlović D, Šegan D, Todorović M (2007) Electrochemical behavior and antioxidant and prooxidant activity of natural phenolics. Molecules 12:2327–2340. https://doi. org/10.3390/12102327 Skeva E, Girousi S (2012) A study of the antioxidative behavior of phenolic acids, in aqueous herb extracts, using a dsDNA biosensor. Cent Eur J Chem 10:1280–1289. https://doi.org/10.2478/ s11532-­012-­0051-­0 Sochor J, Dobes J, Krystofova O et al (2013) Electrochemistry as a tool for studying antioxidant properties. Int J Electrochem Sci 8:8464–8489 Tougas TP, Jannetti JM, Collier WG (1985) Theoretical and experimental response of a biamperometric detector for flow injection analysis. Anal Chem 57:1377–1381. https://doi. org/10.1021/ac00284a044 Vishnu N, Gandhi M, Rajagopal D, Senthil A (2017) Pencil graphite as an elegant electrochemical sensor for separation-free and simultaneous sensing of hypoxanthine, xanthine and uric acid in fish samples, vol 9. pp 2265–2275 Vishnu N, Gandhi M, Badhulika S, Senthil Kumar A (2018) Tea quality testing using 6B pencil lead as an electrochemical sensor, vol 10. pp 2327–2337 Volkov AG, Nyasani EK, Tuckett C et al (2016) Cyclic voltammetry of apple fruits: Memristors in vivo. Bioelectrochemistry 112:9–15. https://doi.org/10.1016/j.bioelechem.2016.07.001 Wang M, Qu Y, Sun J, et al (2016) Electrochemical detection of liquiritin in liquorice based on carbon materials. Int J Electrochem Sci 11:10407–10416. https://doi.org/10.20964/2016.12.24 Williams CA, Ph D, Lamprecht ED (2007) Some commonly fed herbs and other functional foods in equine nutrition: a review. Vet J 178:21–31 Wojdyło A, Oszmiański J, Czemerys R (2007) Antioxidant activity and phenolic compounds in 32 selected herbs. Food Chem 105:940–949. https://doi.org/10.1016/j.foodchem.2007.04.038 Wollenberger U, Schubert F, Scheller FW (1992) Biosensor for sensitive phosphate detection. Sensors Actuators B Chem 7:412–415. https://doi.org/10.1016/0925-­4005(92)80335-­U YANG B, KOTANI A, ARAI K, KUSU F (2001) Estimation of the antioxidant activities of flavonoids from their oxidation potentials. Anal Sci 17:599–604. https://doi.org/10.2116/ analsci.17.599 Yip W, Mahal A (2008) The health care systems of China and India: performance and future challenges. Health Aff 27:921–932. https://doi.org/10.1377/hlthaff.27.4.921 Zhao Z, Lei W, Zhang X et  al (2010) ZnO-based amperometric enzyme biosensors. Sensors 10:1216–1231. https://doi.org/10.3390/s100201216 Zielinska D, Wiczkowski W, Piskula MK (2008) Determination of the relative contribution of quercetin and its glucosides to the antioxidant capacity of onion by cyclic voltammetry and spectrophotometric methods. J Agric Food Chem 56:3524–3531. https://doi.org/10.1021/ jf073521f Ziyatdinova GK, Voloshin AV, Gilmutdinov AK et  al (2006) Application of constant-current coulometry for estimation of plasma total antioxidant capacity and its relationship with transition metal contents. J Pharm Biomed Anal 40:958–963. https://doi.org/10.1016/j. jpba.2005.08.017 4 2015-IETC-Vishnu IETC J. Ind. Chem Soc. Paper.pdf

Chapter 10

Nano-Adsorbents in Wastewater Treatment for Phosphate and Nitrate Removal Nur Diyana Suzaimi, Pei Sean Goh, Nik Ahmad Nizam Nik Malek, Be Cheer Ng, and Ahmad Fauzi Ismail

Abstract  Besides heavy metals, dyes, pharmaceutical wastes etc., the contamination of nutrient ions like nitrate and phosphate are becoming one of the most important water quality concerns. Serious health and environmental issues especially surface water and ground can occur due to overabundance of these ions in water. This action, in many cases, severely affect a water utility’s ability to supply safe and affordable drinking water adequately. As of late, the adsorption is regarded as one of promising method for water remediation due to its application with nanomaterials that enhance the chemical activity and adsorption capacity of nano-adsorbent. A perusal of literature reviews reveals that replacing conventional adsorbents with new generation nano-adsorbents have advanced the adsorption of nitrate and phosphate from aqueous solution. This book chapter furnishes the discussion about the past and present attempts at using variety nano-adsorbents most specifically carbon-­ based, metal-based, polymer-based, silica-based and magnetic-based in order to remove nitrate and phosphate ions. Their adsorption behaviour and performance are discussed, and some patterns implemented are also illuminated. Keywords  Waterbodies · Nanoadsorbents · Polymeric nanomaterials · Metallic nanoparticles · Water purification

N. D. Suzaimi · P. S. Goh (*) · B. C. Ng · A. F. Ismail Advanced Membrane Technology Research Centre (AMTEC), Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysia e-mail: [email protected] N. A. Nizam Nik Malek Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, Johor, Malaysia © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 N. Dasgupta et al. (eds.), Environmental Nanotechnology Volume 5, Environmental Chemistry for a Sustainable World 37, https://doi.org/10.1007/978-3-030-73010-9_10

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10.1  Introduction In waterbodies, phosphorus is usually partitioned as different phases: dissolved phase includes organic/inorganic phosphorus and suspended phase includes amorphous/precipitates phosphorus (Almeelbi and Bezbaruah 2012). The cycle of this element is complex, involving several kinds of phosphorus species with different name. The usual ones are, orthophosphates, polyphosphates, and phosphates (Mezenner and Bensmaili 2009). The reason for this is that the chemical arrangement of phosphorus in the species is different. Phosphate can be both beneficial and harmful to organism depends on the consumption. Meanwhile, nitrogen exists in the form of nitrate together with other forms such as ammonia nitrite, nitrate, dissolved molecular nitrogen, and numerous organic forms. Nitrate and phosphate ions are among the most common anions found in wastewater. Both ions mainly posed by the agricultural run-off containing fertilizers and pesticides alongside the untreated or undertreated disposal of domestic, aquaculture and industries (Bhatnagar and Sillanpää 2011; Hamoudi and Belkacemi 2013). Since the amount of nitrate is essential for the growth of organisms and plants hence, they are dominantly used in the fertilizers and also used as an indicator for surface water quality. Pathways of phosphate and nitrate cycles are shown in Fig. 10.1a and b, respectively. Despite the fact that nitrate is an important nutrient to living organisms, the excessive amount of these anions is deemed to cause eminent problems that stimulates water deterioration and eutrophication (over-fertilization) of algae growth

Fig. 10.1  (a) P cycle; (1) natural occurring P mineral, (2) P as fertilizers, (3) P use in food (as a constituent/preservative), (4) P in human excreta, (5) P discharged to the environment, (6) P in agricultural run-off resulting in diffuse pollution. (Adapted from Bunce et al. 2018). (b) N cycle; (1) N taken up by plants, (2) NO3− and NH4+ from soil and water taken up by plants, (3) ammonification, (4) nitrification, (5) denitrification, (6) NO3− immobilization, (7) NO3−leaching from the soil, (8) release of NH3, gaseous nitrogen and nitrous oxide to the atmosphere. (Adapted from Garcia et al. 2006)

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(Kilpimaa et al. 2014). Loss of biodiversity is one of negative impacts of eutrophication. Large population of algae blooms on water surface will depleted oxygen and block out sunlight from reaching deep in the water, consequently, hamper the survival of aquatic flora and fauna. The water quality in term of unpleasant flavour, bad odour, great turbidity, and low dissolved oxygen concentration will be deteriorated. Eutrophication often requires high-priced surface water treatment to recover water quality. The worst thing of all is that the long-term exposure of nitrate and phosphate through food, water, air, and soil can adversely affect human health. The study on nitrate showed that consumption of food or water with high nitrate concentration may attain cancer, diabetes mellitus and methaemoglobinemia which likely to impinge young children under six months of age (Parvizishad et al. 2017). In the infant’s stomach, nitrate can be converted to nitrite which can block the oxygen transport in bloodstream as it binds to haemoglobin and form methaemoglobin. As a result, the infant will have insufficient oxygen supply and possesses a bluish coloured skin, known as blue baby syndrome (Shrimali and Singh 2001). Besides that, consuming small amounts of phosphorus by drinking or eating may contribute to organ failure and mortality (Eldad and Simon 1991). For these reasons, it is important to keep nitrate and phosphate levels as low as possible. To get rid of the risks, World Health Organization (WHO) has set that 10 mg L−1 and 50 mg L−1 as the guideline values for phosphate and nitrate, respectively in drinking water (WHO 2011). Since access to clean and safe water is essential for our daily consumption, it is important to take good care of our water sources to ensure the continuous supply and maintain sustainable green environment. Therefore, the removal of nitrate and phosphate ions become a primary concern.

10.2  Nitrate and Phosphate Treatment Options In lights of ramification of nitrate and phosphate pollution to ecosystem and human being, scientists and researchers have invented many methods including laboratory and pilot studies as well as discovered many techniques to effectively lower and eliminate the ions content in water sources. The selection of the treatment option is based on various key factors that are relevant for individual water systems ‘needs and priorities. Several treatments with varying degrees of efficiency, cost and ease of operation were applied to eliminate nitrate and phosphate from water treatment. The pollutants are commonly being removed by means of biological methods (e.g. bio-denitrification), chemical methods (e.g. electrocoagulation, chemical precipitation), physical treatment (e.g. reverse osmosis (RO), electrodialysis) and adsorption. A summary on the merits and demerits of nitrate/phosphate treatment methods is presented in Fig. 10.2. Generally, the use of reduction is applied for nitrate as it can be reduced to nitrogen gaseous, ammonia and nitrite. Biological denitrification at full scale in drinking water treatment is mainly limited to Europe while chemical denitrification methods

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Nitrate & Phosphate Treatment Options

Reduction

Biological Denitrification - Zero waste disposal - Non toxic byproduct - High maintenance - Slow

Removal

Chemical Denitrification

Reverse Osmosis

Ion exchange

- High efficiency - Long reaction time - Inconsistent reduction - High waste disposal

- Applicable - Ease of scale up - Expensive energy -Membrane fouling

- Efficient for small and large scale - High cost - Require disposal and post-treatment

Electrocoagulation

- Efficient - Low acid needed - Medium cost - Require waste disposal

Adsorption - Wide applicability - Easy operation - Tedious separation - Adsorbent disposal

Fig. 10.2  Available treatment options for nitrate and phosphate in wastewater

only investigated at pilot-scale (Jensen et al. 2012). The use of microorganism or chemicals are necessary in biological treatment to complete the process as it increases the rate at which regular biodegradation happens. Biological is less efficient than that of chemical denitrification, and usually slow and limited due to high maintenance cost (Bhatnagar and Sillanpää 2011; Tyagi et al. 2018). Previous studies found that chemical denitrification using zero-valent iron can remove >90% ions at the low pH due to high surface to volume ratio (Almeelbi and Bezbaruah 2012; Prashantha Kumar et  al. 2017). However, longer reaction time and higher waste disposal are the main drawbacks for this treatment (Kalaruban 2017). The reliability for large-scale applications like municipal and point-of-use making RO as among the most common nitrate and phosphate treatment alternative (Schoeman 2009). Interestingly, RO can be applied simultaneously for desalination and removal of contaminants. Key factors in the consideration of RO includes pre-­ treatment requirements, waste management, and high operational costs (Archna and Sobti 2012). One deciding factor favouring the selection of RO over ion exchange (IEX) would be the need to address salinity. Despite failed attempts in the past, IEX technology nowadays has been used in many applications including water desalination and deionization (Bunce et al. 2018). IEX is a reversible process that occurred through exchanging similar charged of ions on solid surface with the one in solution. Demineralization and nutrient removal (nitrate, phosphate and ammonium) are the example of applications of IEX in water and wastewater. Typically used ion exchangers for nitrate and phosphate ions are synthetic (polymeric resin) rather than natural (aluminosilicates). Approximately 90% of nitrate as well as phosphate removal efficiency can be achieved by using IEX (Bhatnagar and Sillanpää 2011; Seo et al. 2013). In spite of the good removal, IEX however, faces a few challenges include poor selectivity, inefficient regeneration, and fouling which demand optimization before the process begin (Petruzzelli et al. 2004). Due to its advantages such as no chemicals requirement, less sludge production, small investment costs and fast removal (Koparal and Öütveren 2002) electrocoagulation has been widely used to remove phosphate and nitrate ions from water

10  Nano-Adsorbents in Wastewater Treatment for Phosphate and Nitrate Removal Fig. 10.3  Illustration of adsorption, absorption and desorption process. (Redrawn Samer 2015)

Absorption

Adsorption

adsorbate

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absorbate absorbent absorbent

adsorbent

Desorption

sources. Behbahani et  al. (2011) and Lacasa et  al. (2011) had successfully conducted electrocoagulation for the removal of phosphate and nitrate respectively but the process lack of system for electrocoagulant reactor design, operation and anode passivation. Compared to other conventional methods, adsorption process offers high accessibility of variety adsorbents and produces less sludge hence free from disposal problems (Saad et al. 2008). Adsorption using various adsorbents is a versatile and promising method among other methods for removing pollutants in wastewater. The process of adsorption, adsorption and desorption is illustrated in Fig.  10.3. Adsorption offers relatively simple method, economic viability, easy operation and recovery (Bhatnagar and Sillanpää 2011). High adsorption and desorption efficiency indicate the effectiveness of adsorbent used. In the above context, there is an imperative need to innovate novel adsorbent to enhance the adsorption rate and increase the adsorption capacity for anionic nutrient species. By far, various kind of materials have been assessed for a good adsorbent for the adsorption of nitrate and phosphate anions.

10.3  Key Factors of Nitrate and Phosphate Adsorption A wide range of adsorbents such as silica, activated carbon and metal oxides have been extensively used for wastewater treatment particularly to remove nitrate and phosphate. The effectiveness of this technique is based on the development of an efficient adsorbent (Wang and Peng 2010). The chemical and physical properties of adsorbent significantly influence the phosphate and nitrate adsorption process. According to Abou Taleb et al. (2008) high adsorption capacity and surface reactivity of nitrate and phosphate depends on the affinity surface area and number of specific active cites. Also, the surface area, porosity, particle size, structure and distribution of the adsorbate were another important factor that impact the adsorption

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process (Suzaimi et al. 2019). Therefore, the selection of adsorbent is very crucial to dictate its performance. Besides properties of adsorbent, experimental operating conditions such as solution pH, adsorbent dosage, initial anions concentration, contact time and coexisting ions exert a significant influence on nitrate and phosphate adsorption performance. Thus, the effects of these parameters are to be taken into account. Optimization of such conditions will greatly help in the development of industrial-scale anions removal treatment process. The effects of different parameters usually evaluated in the batch mode experiments. Environmental nitrate and phosphate are always accompanied by other inorganic anions in most kinds of water and wastewater. Chloride, nitrate, bicarbonate, and sulphate are frequent ions in wastewater (He et al. 2017). Their presence could potentially interfere in the nitrate and phosphate adsorption because they would compete against each other for the available sites. Ions would be removed in sequence started with the greatest ionic potential followed by those with lower ionic potentials (Li et al. 2016). Thus, the competitive sorption should be carried out in order to evaluate the selectivity of the adsorbent. Besides exhibiting high adsorption capacity, a good candidate of adsorbent should possess the ability to be regenerated and reproduced for practical application. The regeneration of adsorbent is an important factor to reduce the process cost of wastewater treatment. Generally, the removal of nitrate and phosphate from standard or sample solution was determined using selected adsorbent under batch adsorption mode followed by column operations. Additionally, kinetic and isotherm studies are performed to verify the adsorption capabilities. Adsorption isotherm indicates the amount of ions adsorbed per mass (g) of adsorbent, at a fixed temperature and equilibrium concentration solution while kinetic is the measurement of adsorption rate at a constant concentration (Sadegh et al. 2017). Summarizing from the literature, experimental adsorption data of nitrate and phosphate are described by two common isotherms, namely Langmuir and Freundlich isotherms. Meanwhile, to analyse the mechanism and understand the effect of contact time on the adsorption, pseudo-first-order kinetic or pseudo-second-order kinetic are generally used.

10.4  Progress of Nano-Adsorbents for Nitrate and Phosphate The introduction of nanomaterials has led to changes in wastewater treatment approaches. Nanomaterials (i.e. nanoparticles, nanofibers, and porous materials) refer to tiny particles of material  SO42− > Cr2O7 2− > Cl−. After nitrate removal, MAB-CS can be easily separated and recovered from the solution through external magnet with the recovery efficient of 118  ∼  147%. Overall, although numerous studies available on the application of magnetic-based nano-­ adsorbents but, there still exists knowledge gaps that need to be addressed. For example, the detailed assessment of magnetic-based nano-adsorbents in case of multi pollutant solutions.

10.4.3  Polymer-Based Nano-Adsorbent In the past years, polymer based nano-adsorbent as anion exchange has attracted interest for the anions of environmental concern from aqueous media. It is known as ion exchange resins which the most important group of ion exchange materials. As for the environmental concerns, polymeric adsorbents have been widely used for organic pollutants removal such as heavy metals (El-Kafrawy et al. 2017), dyes (Li et al. 2010; Xiong et al. 2018) and anionic nutrients (Li et al. 2015; Rajeswari et al. 2016; Wu et  al. 2016). Additionally, polymeric adsorbents containing complex ligands like chitosan, cellulose and polyaniline have been applied to enable high degree adsorption towards inorganic pollutants (Thakur et al. 2017). Besides surface modification or functionalization, incorporation of nanoparticles within polymeric matrix has also received great attention due to the outstanding mechanical strength and compatibility of polymer matrix. Moreover, the polymer provides higher stability and processability as support materials (Alaba et al. 2018). Wide array of polymeric adsorbents resins (cation and anion) are available to ionic contaminants from water. Polymerization anion exchanger with iron oxide nanoparticles has been prepared to effectively remove phosphate (Nur 2014). Nanoparticle was incorporated into derived resin Purolite FerrIX A33E with hydrous iron oxide to produce strong, durable and spherical polymer substrate. Removal efficiency increased along with resin dose. This was likely due to the higher availability of surface area for adsorption in resulting adsorbent. For adsorption isotherm data, Langmuir adsorption model was applicable for this study which showed maximum phosphate adsorption capacity approximately 48 mg/g. The adsorption capacity is considered high which possibly due to the contribution of iron oxide

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nanoparticles to the total adsorption capacity of the Purolite resin. About 19 mg/g resin of phosphate ion is adsorbed by inner sphere surface complexation of iron oxide while the remaining being adsorbed by outer sphere complexation on the quaternary ammonium group of Purolite resin (Deliyanni and Bandosz 2011; Loganathan et al. 2013). Overall, this study showed a good efficiency of phosphate adsorption–desorption using polymeric adsorbent, but further studies need to be conducted to know the efficiency of simultaneous nitrate and phosphate removal and effect of other operating conditions such as contact time, pH of solution and the presence of the coexisting ions on the adsorption capacities. A strong basic anion exchange resin, new polymeric adsorbent (NDQ) has been evidenced to demonstrate higher selective adsorption ability toward nitrate in aqueous solution (Wu et al. 2016). NDQ was modified with amine groups to enhance the adsorption capacity. Results revealed that the resin independent of the pH as only small changes were detected. Besides that, this resin also highly selective to nitrate in the aqueous solutions containing other ions. Among the competing ions, SO42− showed adverse effect on nitrate removal followed by HCO3− and Cl−. For sorption behaviour, the material followed the Langmuir adsorption isotherm and adsorption rate fitted well with pseudo-first order. NDQ showed high amount of sorbed nitrate, 221.8 mg/g in comparison to other resins such as Purolite A300, 147.41 mg/g (Song et al. 2012). This probably due to the several mechanisms occurred not only ion-­ exchange mechanism but also by hydrogen bonding from the amino and hydroxyl groups. Attractively, at equilibrium the electric attraction between NO3− and – N(CH3)+ on the surface of the NDQ was also significant to nitrate adsorption. In all, this adsorbent has high potential to be practically used in purification of water resources.

10.4.4  Silica-Based Nano-Adsorbent Numerous studies have been done to investigate the possible silica-based nano-­ adsorbent application in wastewater treatment to remove different pollutants. Silica-­ based adsorbent like zeolite, mesoporous silica, clay and sepeolite are often used for heavy metals, dyes and anions removal. Extensive research effort has been devoted to examining the potential of mesoporous silica. The most widely reported mesoporous silica for nitrate and phosphate removal are MCM-41, MCM-48 and SBA-15 (Hamoudi et al. 2007; Saad et al. 2008; Kim et al. 2015) Unfortunately, high porosity and tremendous surface area of mesoporous silica do not enhance the adsorption because no active sites is available for nitrate and (Shin et al. 2004; Saad et al. 2008; Choi et al. 2011; Hamoudi and Belkacemi 2013). Since modification on nano-sized silica can bring out high performance, several methods have been devised on silica. The commonly adopted modification to improve adsorption capacity includes amine grafting. The amino-groups introduced into silica is protonated with acid to add functionalities to the silica-adsorbent thus providing specific active sites to adsorbents.

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Propylammonium functionalized mesoporous silica for the adsorption of nitrate and phosphate anions have been investigated (Hamoudi and Belkacemi 2013). Desirable properties of highly porous, large surface areas, and appropriate surface functionalization, mesoporous silica materials functionalized with ammonium group were proven to be high-capacity adsorbents for nitrate and phosphate in water phase. Ion exchange mechanism occurred along with adsorption process where Cl− is the main counter anion to exchange the nitrate/phosphate adsorbed on the adsorbent. The results of propylammonium functionalized mesoporous silica via grafting outperformed in comparison to co-condensation for both studies. The process occurred very fast and can be accomplished in less than 5 min with corresponding adsorption capacities reached 45 mg/g for nitrate and 57 mg/g for phosphate. Based on the results, the adsorption process fits well to the pseudo-second order kinetic model. The adsorption behaviour of these synthesized adsorbents is related to the textural and surface properties. On the basis, it can be concluded that the performances of functionalized mesoporous silica materials were significantly high compared to that of unfunctionalized one. There was also effort done on silica-based composites, mesoporous MCM-41 and rice husk as an adsorbent and its feasibility for removing phosphate was evaluated (Seliem et al. 2016). The nanocomposite adsorbent was synthesized using cationic surfactant under the hydrothermal conditions. The rice husk functioned as silica as well as substrate for the MCM-41 deposition. Phosphate uptake was maximized at pH  4–6 and the adsorption capacity achieved was 21.01  mg/g. Good adsorption is in accordance with the previous perchlorate study, reporting that the residual positive charge on the cationic surfactant micelles trapped in silica mesopores contributed towards perchlorate uptake by MCM-41 and rice husk (Seliem et al. 2010, 2016). An upward trend of adsorption capacity was attributed to the high positive surface charge and the forces of attraction towards the negative charge, hence led to an increase in phosphate adsorption. It was also noticed that, the removal efficiency of phosphate was directly proportional to the dosage of adsorbent which primarily driven by the increase in the number of active sites of adsorbent. By keeping initial pH at 6, there was no significant effect on the competition between CO32− and NO3− and SO42− ions. Also, the process was fast as the time taken to reach equilibrium was only as short as 30 min. From the acquired data, phosphate adsorption occurred via chemisorption as the isotherm and kinetic data was best described by Langmuir and pseudo-second-order, respectively.

10.4.5  Metal-Organic Framework Nano-Adsorbent Hitherto, metal-organic framework (MOF) appears to offer the best potential to be used as adsorbent with high adsorption of various pollutants. Several research groups have been devoted to exploring the composites of MOFs for the removal of various kinds of anionic and cationic pollutants from water. Good adsorption performance of MOFs come from its superior ion-exchange property (Prashantha Kumar et  al. 2017). MOF is a virtue class of porous hybrid materials with large

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specific surface area, high porosity, tunable pore channels, and open metal sites (Xie et al. 2017). In addition, MOFs show potential as a cost-effective adsorbent because high yields MOF can be prepared via affordable and green synthetic methods. Combination of MOF with appropriate materials was reported to improve the potential usage of MOF. Overtime, only a few MOFs have been investigated as anions adsorbents. Specifically, La-MOF (Liu et al. 2016), MIL-101(Fe) (Xie et al. 2017) and UiO-66 (Qiu et al. 2017) were developed for adsorptive removal of phosphate. Adsorption behaviours of phosphate on MOFs and the effects of different conditions were studied particularly. Recently, UiO-66 was synthesized and impregnated with PEI for the adsorption of phosphate. The incorporation of PEI with UiO-66 performs well, giving great adsorption of phosphate. From the results, the prodigious increase in phosphate adsorption capacity can be explained on the basis of electrostatic attraction between protonated amines groups in PEI and phosphate ions as well as coordination of hydroxyl on UiO-66 network (Qiu et al. 2017). The adsorption was fast and completed within 50 min, with an adsorption capacity of 73.15 mg/g at a wide pH range (2–7). Xie et al. (2017) synthesized and compared two Fe-based MOFs, MIL-101(Fe) and NH2-MIL-101(Fe) on the phosphate adsorption. Besides can be easily regenerated and reused, MIL-101(Fe) and NH2-MIL-101(Fe) exhibit good performance in both capacity and selectivity of phosphate adsorption. Adsorption isotherms indicates that primary mechanism of MIL-101(Fe) is via interaction between phosphate ions and Fe metal. But it is found that adsorption capacity of the NH2-MIL-101(Fe) increased after being modified. So, the amine and phosphate interaction also involved in the adsorption. In another work, MOF was incorporated with La to enhance the phosphate adsorption from aqueous solution (Liu et al. 2016). Based on characterization analysis results, phosphate removal of La-MOF occurred via electrostatic attraction and ligand exchange reaction between La and phosphate. The presence of high concentration of competing ions such as bromide, chloride, nitrate and sulphate did not affect phosphate adsorption capacity of all three studies. This suggests the high selectivity of MOF towards phosphate ions. Ultimately, MOF can be applied as promising nano-adsorbent for phosphate and nitrate adsorption in aqueous solution. In other study, MOF-5 was synthesized as a novel approach to capture nitrate ions (Mehmandoust et al. 2018). Two MOF-5 which consist of zinc acetate dehydrate and benzene-1,4-dicarboxylate (BDC) were produced, with and without triethylamine by solution and solvothermal methods. Tri-ethylamine acts as capping agent which prevent crystal growth, resulting in small sized of MOF-5 obtained. Characterization results indicated that high surface area of MOF-5 containing triethylamine (1.5 mL) is more suitable candidate for liquid phase absorption. This study involved the effect of the pH solution on the removal of nitrate by MOF-5. Results nitrate absorption was presented in nitrate reduction adsorption. High adsorption was observed after 6 hours in pH solution of 4. Even the study propped MOFs-5 as a good absorbent for the nitrate adsorption however the information is still lacking. Looking forward, further studies should be conducted on the isotherm and kinetic studies and recyclability of MOF-5 to educating mechanism and reusability of adsorbent.

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10.5  Recent Patents and Applications of Nano-Adsorbents The patent granted on the adsorbents, mostly nanocomposite for nitrate and phosphate supported the applicability of the nano-adsorbent at commercial scale. However, the implementation of the present information and advanced research are mandatory to further explore the concealed potential of nanomaterials. Inspired by immense development in magnetic nanoparticles synthesis, it has been noticed that most of patents available for nitrate and phosphate related to the usage of magnetic nanoparticles. As for phosphate removal, great ability of adsorbent to recover phosphate is enticing features particularly in the invention. Through phosphate recovery from wastewater, recovered phosphate can be recycled as substitute to phosphorus fertilizer. A method for preparing biodegradable- adsorbents on the basis of iron-­containing polymer and application of adsorbents is proposed by patent US9359228B2 (Bezbaruah et al. 2017). The method includes preparing iron-functionalized alginate (FFA) and iron-crosslinked alginate (FCA) in form of beads. Reaction between magnetic source, FeCl2 with sodium alginate under certain condition yielding iron-­ functionalized alginate beads. Such beads facilitate easy handling and recovery process, while alginate was chosen because its advantageous qualities of biocompatible and biodegradable. Also included in the invention is a fertilizer making process. The spent FFA beads as fertilizer can be applied without any post-treatment. The invention showed FCA beads works much better than FFA beads, achieving complete phosphate removal within 12 h. Common interfere ions (e.g. nitrate, sulphate and chloride) show no significant influence on the adsorption. Further, FCA removal efficiency was compared with another three different alginate-based adsorbents (Ca-cross-linked alginate/CCA, and NZVI entrapped in Ca-cross-linked alginate/ NCC). The comparison indicated that FCA beads performed substantially well with maximum capacity of 14.77 mg/g and 100% removal efficiency in 12 hours. This can be inferred that presence of iron in alginate beads enhanced the phosphate adsorption capacity. Experimental data showed good agreement with Freundlich isotherm and pseudo-second order kinetic. Advantageously, FCA beads are convenient to be operated either in large or small-scale treatment as well as field operation. Accordingly, the method has an excellent application prospect in wastewater remediation. Recently, an invention on the process for the producing and using of composite magnesium oxide, iron oxide, and biochar was disclosed by Louisiana State University and Agricultural and Mechanical College (Wang et al. 2018). The produced MgO-impregnated magnetic biochar (MMSB) composite be used to reduce phosphate and other wastewater pollutants including nitrate, ammonium, and organic compounds. The testing mainly focusses on the effect of Mg content and aqueous pH.  Comparative studies exhibit that MMSB possess higher adsorption capacity and good phosphate recovery than unmodified sugarcane harvest residue biochar (SB) and low-Mg magnetic biochar (MSB). The Mg levels in composite is important as it promotes the adsorptivity MMSB for phosphate. With increasing

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percentage of Mg loading, the phosphate adsorption remarkably increased. For instance, adsorption capacity of 20% Mg-impregnated MMSB was determined at about 121.25 mg/g at pH 4 and more than 99.5% phosphate recovered. Separation of adsorbent after adsorption from solution with become easier the help of a magnet. The separation without tedious filtration or centrifugation increase efficiency in wastewater treating. Overall, the MMSB has proven as a promising adsorbent. In addition, MMSB has good regenerative ability and satisfying recovery pollutant solutes. Accordingly, recovered phosphates as fertilizer have been applied successfully, enabling healthy plant growth. They discovered the composites has the potential to permeate industrial sectors and influence their development toward sustainability since their production process are cost effective and eco-friendly. US20160176730A1 patent discloses the instant application of the magnetic-­ based nano-adsorbent for reducing impurities in stagnant water, particularly nitrate ions (Bahrebar and Nia 2016). The produced adsorbent, Fe3O4@ MCM-41– NH2 was implemented as nano-adsorbent in aqueous solution containing nitrate ions. Design of synthesizing route of Fe3O4@ MCM-41– NH2 and its application in removing nitrate is summarized in Fig. 10.10. Fe3O4@ MCM-41– NH2 has successfully removed up to 80% nitrate ions. After the adsorption, the adsorbent was separated by the magnetic field by using a bar magnet. For better understanding, the invention provides a method of producing the adsorbent as well as their roles in capturing high nitrate species. Mesoporous silica (MCM-41) was coated on the Fe3O4 nanoparticles to create core. As MCM-41 was able to activate the shell in aqueous, modification is paramount. (3-Aminopropyl)triethoxysilane (APTES) was functionalized with Fe3O4@MCM-41 producing Fe3O4@MCM-41– NH2, which

Fig. 10.10  Design of synthesizing route of Fe3O4@ MCM-41– NH2 and its application in removing nitrate

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behaves as a host for different toxins. Addition of both, MCM-41 and APTES as ligand creates superparamagnetic nanoparticles. In one specific example, the measuring device shows only 20% pollutant remaining in the water after the removal of the pollutant bounded to the superparamagnetic particles. The method of modified Fe3O4 with MCM-41 and APTES provides broad prospects for the treatment of wastewater contaminants. It effectively improves the adsorption efficiency of removal of contaminants. Invention assigned by Howard University focused on polymer-based adsorbents (Mitchell and Yang 2020). More specifically, the invention relates to polysaccharide-­ polyamine copolymer as potential material for phosphate removal from human body. The invention crosslinked polysaccharide with polyamine motivated by versatility properties of polysaccharide-based materials including non-toxicity, modifiable, high reactivity and good adsorptivity. Crosslink with polyamine provides cationic charge after protonation, resulting to more adsorption sites. Methods for making the polysaccharide-polyamine copolymeric and the cationic copolymeric materials also are described. The method includes oxidizing backbone, soluble 2,3-dialdehyde cellulose (DAC) by sodium periodate followed by reacting the polysaccharide-­derived polymers containing DAC with amino polymers to provide the polysaccharide-polyamine copolymeric materials. For example, polysaccharide-­ polyamine copolymers in hydrogel form were synthesized by reacting DAC with branched polyethyleneimine (PEI) with 1:20 ratio. The effectiveness was tested on mice. Mice administered with 1% polysaccharide-polyamine copolymers for seven days had a 43.8  ±  5.2% decrease in total 24-hour urinary phosphorus. Results exhibit the invention of polysaccharide-polyamine copolymers to reduce the phosphate was a success without any significant effect. Therefore, the application of polysaccharide-polyamine copolymers is safe. Despite for removal from human body, covalently cross-linked copolymer accordance with the invention can be utilized as a high capacity anion-exchanger to remove nitrates, phosphates, and metal anions from wastewater to prevent environmental pollution as well. From analysis of recent literature and patents, we clearly show novel nanomaterials adsorbents with improved/controlled physical and chemical properties have good performance on nitrate and phosphate removal. Also, there are no adverse effect on the structural or functional activities of the nanomaterials. An assessment of their patents and industries application in wastewater treatment is provided in Table 10.2.

10.6  Future Outlooks and Conclusion Numerous materials have been assessed in recent years to boost the efficiency and adsorption capacities of nitrate and phosphate contaminants from wastewater. A comparison on some typical nano-adsorbents used for phosphate and nitrate removal is presented in Table 10.1. The optimum operating conditions in term of solution chemistry and contact time obtained are included. Collectively, pH of the solution

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Table 10.1  Comparison of adsorption capacities of various nano-adsorbents for nitrate and phosphate ions removal Optimal condition Carbon-based Biomass gasification AC

Adsorption capacity (mg/g)

References

Co: 25 mg L−1 t: 60 min, pH: 6 Co: 10–50 mg L−1 t: 60 min, pH: 4 Co: 50–100 mg L−1 t: 60 min, pH: 4 Co: 30 mg L−1 t: 720 min, pH: 4

Nitrate: 10.99 Phosphate: 13.55 Nitrate: 43.1

Co: 20, 60 mg g−1 t: 120 min, pH: 7 Co: 50 mg g−1 t: 1440 min, pH: ≤ 6 Co: 20 mg g−1 t: 1440 min, pH: 6 Co: 20 mg g−1 t: 90, 30 min, pH: 4–8

Nitrate: 41.90 Phosphate: 62.72 Nitrate: 89.58 Phosphate: 57.49 Nitrate: 19.45 Phosphate: 33.16 Nitrate: 138.88 Phosphate: 116.28

Cui et al. (2019)

Co: 100 mg g−1 t: 30–40 min, pH: 5.5, 6 Co: 100 mg g−1 t: 45, 60 min, pH: 3–8 Co: 100–200 mg g−1 pH: 3–10

Nitrate: 38.40 Phosphate: 42.95

Suresh Kumar et al. (2019)

Nitrate: 84.09 Phosphate: 181.29 Nitrate: 221.8

Banu and Meenakshi (2017) Wu et al. (2016)

Co: 100 mg g−1 t: 45, 60 min, pH: 3–8 Co: 100 mg g−1 Functionalized silica t: 30 min, pH: 6 (C3H6-NH) Metal organic framework-based La-MOF t: 80 min, pH: 6.25 MOF 5 (II) t: 360 min, pH: 4

Nitrate: 7.4 Phosphate: 0.1 Phosphate: 21.01

Saad et al. (2008)

Phosphate: 73.15 Nitrate: –

NH2-MIL-101(Fe) UiO-66/PEI

Phosphate: 124.38 Phosphate: 142.04

Liu et al. 2016) Mehmandoust et al. (2018) Xie et al. (2017). Qiu et al. (2017)

Fenton reagents – AC Multi-walled carbon nanotubes (MWCNT) Graphene nanosheet – LaOH Metal-based Al hydroxide Al – biochar Amine/aluminiummanganese bi-metal La doped magnetic reduced graphene oxide Polymer-based Amine-functionalized magnetic chitosan beads Chitosan quaternized resin Adsorbent (NDQ) modified with amino and quaternary ammonium groups Silica-based MCM-48 silica – NH2

t: 30 min t: 50 min, pH: 2–7

Nitrate: 183.11 Phosphate: 41.96

Kilpimaa et al. (2014) Ahmadi et al. (2017) Alimohammadi et al. (2016) Zhang et al. (2014)

Yin et al. (2018) Wu et al. (2019) Rashidi Nodeh et al. (2017)

Seliem et al. (2016)

plays a prominent role in regulating nitrate and phosphate adsorption and the mechanism was predominantly governed by electrostatic attraction between negatively charged adsorbate with positively charged adsorbent. As often been observed, Langmuir isotherm model (higher correlation coefficient) was better suited than

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Table 10.2  Several patents on related applications of nanomaterials Patent no. US10849927B2

Title Polysaccharide-polyamine copolymers for removal of phosphate

Summary Polysaccharide-polyamine copolymers provides cationic sites for high removal of phosphate. Design multiple crystalline and US20180155214A1 Compositions and amorphous calcium silicate methods for the removal compositions to effectively of phosphates and other remove and recover nitrate, contaminants from phosphate in a fertilizer form. aqueous solutions Effective magnetic metal oxide US2018016162A1 Magnetic metal oxide biochar was producing by biochar composite particles, and their use in proper addition of metal Mg/ recovering pollutants from Fe, hence demonstrated a superior phosphate adsorption aqueous solution ability. Producing biodegradable US009359228B2 Iron-functionalized alginate for phosphate and material comprising iron-­ other contaminant removal functionalized alginate under conditions and for a time and recovery from effective to yield iron-­ aqueous solutions functionalized alginate. US20160176730A1 Removal of nitrate from Implementation of Fe2O3 water nanoparticles functionalized with MCM-41 and APTES creating supermagnetic particles for pollutant removal Synthesis, fabrication and US20150353381A1 Porous nanocomposite application of nanocomposite polymers for water polymers in several form such treatment as beads, membrane and porous sponge

References Mitchell and Yang (2020)

Odom and Ivey (2018)

Wang et al. (2018)

Bezbaruah et al. (2017)

Bahrebar and Nia (2016)

Rodrigues (2015)

Freundlich model for stimulating nitrate and phosphate adsorption on nano-­ adsorbent. The model assuming monolayer adsorption and takes place at homogeneous sites on adsorbent surface. For nitrate and phosphate adsorption kinetics, the adsorptions proceed favourably using both models, pseudo-first-order and pseudo-­ second order. However, most of the studies proved that pseudo-second-order model is more appropriate to simulate the adsorption process. This suggest the adsorption process is attributed to chemisorption between nitrate or phosphate and nano-­ adsorbent (Vikrant et al. 2018). This book chapter concludes that nanomaterials adsorbents such as nano-metal, nano-metal oxides, CNTs, mesoporous silica and nanocomposite adsorbents are particularly attractive for wastewater application since they are evidenced to perform better than the conventional materials due to unique morphological properties and abundant adsorption sites. Therefore, the nanotechnology could be regarded as

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good alternative for nitrate/phosphate removal over conventional techniques. Despite demonstrated good performance, there are some issues to be arisen of using such nano-adsorbents for the removal of nitrate/phosphate and possible approach to overcome them. This include, large scale application, complex synthesis and unstable at varying environmental conditions. In the above context, further work needs to be done to tailor composite adsorbents ‘structural and chemical properties. Hence, performance of nano-adsorbents after modification, after regeneration and application of nano-adsorbents applications at commercial level could be enhanced. In addition, the presence or absence of these co-contaminants also influence the ions removal rates, so nanoparticles can also be designed such that they can be used for simultaneous removal of co-contaminants along with nitrate/phosphate. Acknowledgement  The author would like to acknowledge the financial support provided by Ministry of Higher Education Malaysia under HiCOE Grant 4J183.

References Geim AK, Novoselov KS (2007) The rise of graphene. Nat Mater 6:183–191. https://doi. org/10.1038/nmat1849 Abou Taleb MF, Mahmoud GA, Elsigeny SM, Hegazy ESA (2008) Adsorption and desorption of phosphate and nitrate ions using quaternary (polypropylene-g-NN-dimethylamino ethylmethacrylate) graft copolymer. J Hazard Mater 159:372–379. https://doi.org/10.1016/j. jhazmat.2008.02.028 Ahmadi M, Rahmani H, Ramavandi B, Kakavandi B (2017) Removal of nitrate from aqueous solution using using activated carbon modified with Fenton reagents. Desalin Water Treat 76:265–275. https://doi.org/10.5004/dwt.2017.20705 Ahmadzadeh Tofighy M, Mohammadi T (2012) Nitrate removal from water using functionalized carbon nanotube sheets. Chem Eng Res Des 90:1815–1822. https://doi.org/10.1016/j. cherd.2012.04.001 Alaba PA, Oladoja NA, Sani YM, et  al (2018) Insight into wastewater decontamination using polymeric adsorbents. J Environ Chem Eng 6:1651–1672. https://doi.org/10.1016/j. jece.2018.02.019 Alimohammadi V, Sedighi M, Jabbari E (2016) Response surface modeling and optimization of nitrate removal from aqueous solutions using magnetic multi-walled carbon nanotubes. J Environ Chem Eng 4:4525–4535. https://doi.org/10.1016/j.jece.2016.10.017 Almeelbi T, Bezbaruah A (2012) Aqueous phosphate removal using nanoscale zero-valent iron. J Nanopart Res 14:900. https://doi.org/10.1007/s11051-­012-­0900-­y Anjum M, Miandad R, Waqas M et  al (2016) Remediation of wastewater using various nano-­ materials. Arab J Chem. https://doi.org/10.1016/j.arabjc.2016.10.004 Archna A, Kulkarni RM (2016) Denitrification of groundwater using graphene, graphene oxide and nanocomposites. Int J Res Eng Technol 05:10–14. https://doi.org/10.15623/ijret.2016.0527003 Archna SKS, Sobti RC (2012) Nitrate removal from ground water: a review. E-J Chem 9:1667–1675 Aswin Kumar I, Viswanathan N (2018) Development and reuse of amine-grafted chitosan hybrid beads in the retention of nitrate and phosphate. J Chem Eng Data 63:147–158. https://doi. org/10.1021/acs.jced.7b00751 Bahrebar S, Nia AM (2016) Removal of nitrate from water (US20160176730A1). United States Patent. https://patents.google.com/patent/US20160176730

366

N. D. Suzaimi et al.

Banu HT, Meenakshi S (2017) One pot synthesis of chitosan grafted quaternized resin for the removal of nitrate and phosphate from aqueous solution. Int J Biol Macromol 104:1517–1527. https://doi.org/10.1016/j.ijbiomac.2017.03.043 Basheer AA (2018) New generation nano-adsorbents for the removal of emerging contaminants in water. J Mol Liq 261:583–593. https://doi.org/10.1016/j.molliq.2018.04.021 Behbahani M, Alavi Moghaddam MR, Arami M (2011) A comparison between aluminum and iron electrodes on removal of phosphate from aqueous solutions by electrocoagulation process. Int. J. Environ. Res 5:403–412. https://doi.org/10.22059/IJER.2011.325 Bezbaruah A, Almeelbi TB, Quamme M (2017) Iron - functionalized alginate for phosphate and other contaminant removal and recovery from aqueous solutions (US9815710B2). United States Patent. https://patents.google.com/patent/US9815710B2/en Bhatkhande DS, Pangarkar VG, Beenackers AACM (2002) Photocatalytic degradation for environmental applications  – a review. J Chem Technol Biotechnol 77:102–116. https://doi. org/10.1002/jctb.532 Bhatnagar A, Kumar E, Sillanpää M (2010) Nitrate removal from water by nano-alumina: Characterization and sorption studies. Chem Eng J 163:317–323. https://doi.org/10.1016/j. cej.2010.08.008 Bhatnagar A, Sillanpää M (2011) A review of emerging adsorbents for nitrate removal from water. Chem Eng J 168:493–504. https://doi.org/10.1016/j.cej.2011.01.103 Bunce JT, Ndam E, Ofiteru ID et al (2018) A review of phosphorus removal technologies and their applicability to small-scale domestic wastewater treatment systems. Front Environ Sci 6:1–15. https://doi.org/10.3389/fenvs.2018.00008 Choi J-W, Lee S-Y, Chung S-G et al (2011) Removal of phosphate from aqueous solution by functionalized mesoporous materials. Water Air Soil Pollut 222:243–254. https://doi.org/10.1007/ s11270-­011-­0820-­y Cui X, Li H, Yao Z et al (2019) Removal of nitrate and phosphate by chitosan composited beads derived from crude oil refinery waste: Sorption and cost-benefit analysis. J Clean Prod 207:846–856. https://doi.org/10.1016/j.jclepro.2018.10.027 Cumbal L, Sengupta AK (2005) Arsenic removal using polymer-supported hydrated iron(III) oxide nanoparticles: role of Donnan membrane effect. Environ Sci Technol 39:6508–6515. https://doi.org/10.1021/es050175e Deliyanni E, Bandosz TJ (2011) Importance of carbon surface chemistry in development of iron-­ carbon composite adsorbents for arsenate removal. J Hazard Mater 186:667–674. https://doi. org/10.1016/j.jhazmat.2010.11.055 El-Kafrawy AF, El-Saeed SM, Farag RK et  al (2017) Adsorbents based on natural polymers for removal of some heavy metals from aqueous solution. Egypt J Pet 26:23–32. https://doi. org/10.1016/j.ejpe.2016.02.007 Eldad A, Simon GA (1991) The phosphorous burn  – a preliminary comparative experimental study of various forms of treatment. Burns 17:198–200. https://doi. org/10.1016/0305-­4179(91)90103-­N Ferroudj N, Nzimoto J, Davidson A et al (2013) Maghemite nanoparticles and maghemite/silica nanocomposite microspheres as magnetic Fenton catalysts for the removal of water pollutants. Appl Catal B Environ 136–137:9–18. https://doi.org/10.1016/J.APCATB.2013.01.046 Garcia F, Ciceron D, Saboni A, Alexandrova S (2006) Nitrate ions elimination from drinking water by nanofiltration: Membrane choice. Sep Purif Technol 52:196–200. https://doi.org/10.1016/j. seppur.2006.03.023 Gupta VK, Tyagi I, Sadegh H et  al (2015) Nanoparticles as adsorbent; a positive approach for removal of noxious metal ions: a review. Sci Technol Dev 34:195–214. https://doi.org/10.3923/ std.2015.195.214 Hamoudi S, Belkacemi K (2013) Adsorption of nitrate and phosphate ions from aqueous solutions using organically-functionalized silica materials: Kinetic modeling. Fuel 110:107–113. https:// doi.org/10.1016/j.fuel.2012.09.066 Hamoudi S, Saad R, Belkacemi K (2007) Adsorptive removal of phosphate and nitrate anions from aqueous solutions using ammonium-functionalized mesoporous silica. Ind Eng Chem Res 46:8806–8812. https://doi.org/10.1021/ie070195k

10  Nano-Adsorbents in Wastewater Treatment for Phosphate and Nitrate Removal

367

He Y, Li J, Long M et  al (2017) Tuning pore size of mesoporous silica nanoparticles simply by varying reaction parameters. J Non-Cryst Solids 457:9–12. https://doi.org/10.1016/j. jnoncrysol.2016.11.023 Huang Y, Lee X, Grattieri M et al (2018) A sustainable adsorbent for phosphate removal: modifying multi-walled carbon nanotubes with chitosan. J Mater Sci 53:12641–12649. https://doi. org/10.1007/s10853-­018-­2494-­y Jensen VB, Darby JL, Seidel C, Gorman C (2012) Drinking water treatment for nitrate. Technical report 6 in: Addressing Nitrate in California’s Drinking Water with a Focus on Tulare Lake Basin and Salinas Valley Groundwater Kalaruban M (2017) Surface-modified adsorbents Mahatheva Kalaruban A Thesis submitted in fulfillment for the degree of Doctoral of Philosophy Kilpimaa S, Runtti H, Kangas T et  al (2014) Removal of phosphate and nitrate over a modified carbon residue from biomass gasification. Chem Eng Res Des 92:1923–1933. https://doi. org/10.1016/j.cherd.2014.03.019 Kim JY, Balathanigaimani MS, Moon H (2015) Adsorptive removal of nitrate and phosphate using MCM-48, SBA-15, chitosan, and volcanic pumice. Water Air Soil Pollut 226:1–11. https://doi. org/10.1007/s11270-­015-­2692-­z Koparal AS, Öütveren ÜB (2002) Removal of nitrate from water by electroreduction and electrocoagulation. J Hazard Mater 89:83–94. https://doi.org/10.1016/S0304-­3894(01)00301-­6 Lacasa E, Cañizares P, Sáez C et al (2011) Removal of nitrates from groundwater by electrocoagulation. Chem Eng J 171:1012–1017. https://doi.org/10.1016/j.cej.2011.04.053 Li B, Zhou F, Huang K et al (2016) Highly efficient removal of lead and cadmium during wastewater irrigation using a polyethylenimine-grafted gelatin sponge. Sci Rep 6:1–9. https://doi. org/10.1038/srep33573 Li Q, Yue Q, Su Y et  al (2010) Equilibrium, thermodynamics and process design to minimize adsorbent amount for the adsorption of acid dyes onto cationic polymer-loaded bentonite. Chem Eng J 158:489–497. https://doi.org/10.1016/j.cej.2010.01.033 Li R, Wang JJ, Zhou B et al (2017) Simultaneous capture removal of phosphate, ammonium and organic substances by MgO impregnated biochar and its potential use in swine wastewater treatment. J Clean Prod 147:96–107. https://doi.org/10.1016/J.JCLEPRO.2017.01.069 Li W, Zhang H, Sheng G, Yu H (2015) Roles of extracellular polymeric substances in enhanced biological phosphorus removal process. Water Res 86:85–95. https://doi.org/10.1016/j. watres.2015.06.034 Liu H, Guo W, Liu Z et al (2016) Effective adsorption of phosphate from aqueous solution by La-based metal–organic frameworks. RSC Adv 6:105282–105287. https://doi.org/10.1039/ C6RA24568D Loganathan P, Vigneswaran S, Kandasamy J (2013) Enhanced removal of nitrate from water using surface modification of adsorbents  – a review. J Environ Manag 131:363–374. https://doi. org/10.1016/j.jenvman.2013.09.034 Manjunath SV, Kumar M (2018) Evaluation of single-component and multi-component adsorption of metronidazole, phosphate and nitrate on activated carbon from Prosopis juliflora. Chem Eng J 346:525–534. https://doi.org/10.1016/J.CEJ.2018.04.013 Mehmandoust MR, Motakef-Kazemi N, Ashouri F (2018) Nitrate adsorption from aqueous solution by metal–organic framework MOF-5. Iranian J Sci Technol Trans A Sci 6. https://doi. org/10.1007/s40995-­017-­0423-­6 Mezenner NY, Bensmaili A (2009) Kinetics and thermodynamic study of phosphate adsorption on iron hydroxide-eggshell waste. Chem Eng J 147:87–96. https://doi.org/10.1016/j. cej.2008.06.024 Mikhak A, Sohrabi A, Kassaee MZ et al (2017) Removal of nitrate and phosphate from water by clinoptilolite-supported iron hydroxide nanoparticle. Arab J Sci Eng 42:2433–2439. https:// doi.org/10.1007/s13369-­017-­2432-­3 Mitchell JW, Yang D (2020) Polysaccharide-polyamine copolymers for removal of phosphate  (US10849927B2). United States Patent. https://patents.google.com/patent/ US10849927B2/en

368

N. D. Suzaimi et al.

Nur T (2014) Nitrate, phosphate and fluoride removal from water using adsorption process Odom SA, Ivey DJ (2018). Compositions and methods for the removal of phosphates and other contaminants from aqueous solutions  (US20180155214). United States of America. https:// patentscope.wipo.int/search/en/detail.jsf;jsessionid=4D096EDEE388421A62AC703C 3F8D2369.wapp2nB?docId=US219628446&recNum=29327&office=&queryString=&prevFi lter=&sortOption=Pub+Date+Desc&maxRec=69701871 Ota K, Amano Y, Aikawa M, Machida M (2013) Removal of nitrate ions from water by activated carbons (ACs) – Influence of surface chemistry of ACs and coexisting chloride and sulfate ions. Appl Surf Sci 276:838–842. https://doi.org/10.1016/j.apsusc.2013.03.053 Öztürk N, Bektaş TE (2004) Nitrate removal from aqueous solution by adsorption onto various materials. J Hazard Mater 112:155–162. https://doi.org/10.1016/j.jhazmat.2004.05.001 Parvizishad M, Dalvand A, Mahvi AH, Goodarzi F (2017) A review of adverse effects and benefits of nitrate and nitrite in drinking water and food on human health. Health Scope 6. https://doi. org/10.5812/jhealthscope.14164.Review Petruzzelli D, Dell’Erba A, Liberti L et  al (2004) A phosphate-selective sorbent for the REM NUT® process: field experience at Massafra Wastewater Treatment Plant. React Funct Polym 60:195–202. https://doi.org/10.1016/j.reactfunctpolym.2004.02.023 Prashantha Kumar TKM, Mandlimath TR, Sangeetha P et al (2017) Nanoscale materials as sorbents for nitrate and phosphate removal from water. Environ Chem Lett 16:389–400. https:// doi.org/10.1007/s10311-­017-­0682-­7 Qiu H, Yang L, Liu F et  al (2017) Highly selective capture of phosphate ions from water by a water stable metal-organic framework modified with polyethyleneimine. Environ Sci Pollut Res 24:23694–23703. https://doi.org/10.1007/s11356-­017-­9946-­9 Qu X, Alvarez PJJ, Li Q (2013) Applications of nanotechnology in water and wastewater treatment. Water Res 47:3931–3946. https://doi.org/10.1016/j.watres.2012.09.058 Rajeswari A, Amalraj A, Pius A (2016) Adsorption studies for the removal of nitrate using chitosan / PEG and chitosan / PVA polymer composites. J Water Process Eng 9:123–134. https://doi. org/10.1016/j.jwpe.2015.12.002 Rashidi Nodeh H, Sereshti H, Zamiri Afsharian E, Nouri N (2017) Enhanced removal of phosphate and nitrate ions from aqueous media using nanosized lanthanum hydrous doped on magnetic graphene nanocomposite. J Environ Manag 197:265–274. https://doi.org/10.1016/j. jenvman.2017.04.004 Rodrigues DF (2015) Porous nanocomposite polymers for water treatment (US20150353381A1). United States Patent. https://patents.google.com/patent/US20150353381 Saad R, Hamoudi S, Belkacemi K (2008) Adsorption of phosphate and nitrate anions on ammonium-­ functionnalized mesoporous silicas. J Porous Mater 15:315–323. https://doi. org/10.1007/s10934-­006-­9095-­x Sadegh H, Ali GAM, Gupta VK et al (2017) The role of nanomaterials as effective adsorbents and their applications in wastewater treatment. J Nanostruct Chem 7:1–14. https://doi.org/10.1007/ s40097-­017-­0219-­4 Samer M (2015) Biological and chemical wastewater treatment processes. In: Wastewater Treatment Engineering. 1–50. https://doi.org/10.5772/61250 Sani HA, Ahmad MB, Hussein MZ et al (2017) Nanocomposite of ZnO with montmorillonite for removal of lead and copper ions from aqueous solutions. Process Saf Environ Prot 109:97–105. https://doi.org/10.1016/J.PSEP.2017.03.024 Santhosh C, Velmurugan V, Jacob G et al (2016) Role of nanomaterials in water treatment applications: A review. Chem Eng J 306:1116–1137 Schoeman JJ (2009) Nitrate-nitrogen removal with small-scale reverse osmosis, electrodialysis and ion-exchange units in rural areas. Water SA 35:721–728. https://doi.org/10.4314/wsa. v35i5.49198 Seliem MK, Komarneni S, Abu Khadra MR (2016) Phosphate removal from solution by composite of MCM-41 silica with rice husk: Kinetic and equilibrium studies. Microporous Mesoporous Mater 224:51–57. https://doi.org/10.1016/j.micromeso.2015.11.011

10  Nano-Adsorbents in Wastewater Treatment for Phosphate and Nitrate Removal

369

Seliem MK, Komarneni S, Parette R et al (2010) Composites of MCM-41 silica with rice husk: hydrothermal synthesis, characterisation and application for perchlorate separation. Mater Res Innov 14:351–354. https://doi.org/10.1179/143307510X12820854749312 Seo YI, Hong KH, Kim SH et al (2013) Phosphorus removal from wastewater by ionic exchange using a surface-modified Al alloy filter. J Ind Eng Chem 19:744–747. https://doi.org/10.1016/j. jiec.2012.11.008 Shin EW, Han JS, Jang M et al (2004) Phosphate adsorption on aluminum-impregnated mesoporous silicates: surface structure and behavior of adsorbents. Environ Sci Technol 38:912–917. https://doi.org/10.1021/es030488e Shrimali M, Singh K (2001) New methods of nitrate removal from water. Environ Pollut 112:351–359. https://doi.org/10.1016/S0269-­7491(00)00147-­0 Song H, Zhou Y, Li A, Mueller S (2012) Selective removal of nitrate from water by a macroporous strong basic anion exchange resin. Desalination 296:53–60. https://doi.org/10.1016/j. desal.2012.04.003 Song W, Gao B, Xu X et al (2016) Adsorption of nitrate from aqueous solution by magnetic amine-­ crosslinked biopolymer based corn stalk and its chemical regeneration property. J Hazard Mater 304:280–290. https://doi.org/10.1016/j.jhazmat.2015.10.073 Suresh Kumar P, Korving L, Keesman KJ et al (2019) Effect of pore size distribution and particle size of porous metal oxides on phosphate adsorption capacity and kinetics. Chem Eng J 358:160–169. https://doi.org/10.1016/j.cej.2018.09.202 Suzaimi ND, Goh PS, Malek NANN, et al (2019) Performance of branched polyethyleneimine grafted porous rice husk silica in treating nitrate-rich wastewater via adsorption. J Environ Chem Eng 7:103235. https://doi.org/10.1016/j.jece.2019.103235 Thakur AK, Nisola GM, Limjuco LA et al (2017) Polyethylenimine-modified mesoporous silica adsorbent for simultaneous removal of Cd(II) and Ni(II) from aqueous solution. J Ind Eng Chem 49:133–144. https://doi.org/10.1016/j.jiec.2017.01.019 Tyagi S, Rawtani D, Khatri N, Tharmavaram M (2018) Strategies for Nitrate removal from aqueous environment using Nanotechnology: a review. J Water Proc Eng 21:84–95. https://doi. org/10.1016/j.jwpe.2017.12.005 Vikrant K, Kim KH, Ok YS et al (2018) Engineered/designer biochar for the removal of phosphate in water and wastewater. Sci Total Environ 616–617:1242–1260. https://doi.org/10.1016/j. scitotenv.2017.10.193 Wang JJ, Li R, Zhou B. (2018) Magnetic metal oxide biochar composite particles, and their use in recovering pollutants from aqueous solution (US20180016162). United States Patent. https:// patents.google.com/patent/US20180016162A1/en Wang S, Peng Y (2010) Natural zeolites as effective adsorbents in water and wastewater treatment. Chem Eng J 156:11–24. https://doi.org/10.1016/j.cej.2009.10.029 World Health Organization (2011) Guidelines for Drinking-Water Quality, 4th ed. WHO Press, Geneva Wu B, Fang L, Fortner JD et al (2017) Highly efficient and selective phosphate removal from wastewater by magnetically recoverable La(OH)3/Fe3O4 nanocomposites. Water Res 126:179–188. https://doi.org/10.1016/j.watres.2017.09.034 Wu K, Li Y, Liu T et al (2019) The simultaneous adsorption of nitrate and phosphate by an organic-­ modified aluminum-manganese bimetal oxide: Adsorption properties and mechanisms. Appl Surf Sci 478:539–551. https://doi.org/10.1016/j.apsusc.2019.01.194 Wu Y, Wang Y, Wang J et al (2016) Nitrate removal from water by new polymeric adsorbent modified with amino and quaternary ammonium groups: Batch and column adsorption study. J Taiwan Inst Chem Eng 66:191–199. https://doi.org/10.1016/j.jtice.2016.06.019 Xie J, Lin Y, Li C et al (2014) Removal and recovery of phosphate from water by activated aluminum oxide and lanthanum oxide. Powder Technol 269:351–357. https://doi.org/10.1016/j. powtec.2014.09.024

370

N. D. Suzaimi et al.

Xie Q, Li Y, Lv Z et  al (2017) Effective adsorption and removal of phosphate from aqueous solutions and eutrophic water by Fe-based MOFs of MIL-101. Sci Rep 7:3316. https://doi. org/10.1038/s41598-­017-­03526-­x Xiong B, Wang N, Chen Y, Peng H (2018) Self-assembly of alginate/polyethyleneimine multilayer onto magnetic microspheres as an effective adsorbent for removal of anionic dyes. J Appl Polym Sci 135:1–11. https://doi.org/10.1002/app.45876 Yean S, Cong L, Yavuz CT et al (2005) Effect of magnetite particle size on adsorption and desorption of arsenite and arsenate. J Mater Res 20:3255–3264. https://doi.org/10.1557/jmr.2005.0403 Yin Q, Ren H, Wang R, Zhao Z (2018) Evaluation of nitrate and phosphate adsorption on Al-modified biochar: influence of Al content. Sci Total Environ 631–632:895–903. https://doi. org/10.1016/j.scitotenv.2018.03.091 Zhang L, Gao Y, Zhou Q, et  al (2014) High-performance removal of phosphate from water by graphene nanosheets supported lanthanum hydroxide nanoparticles. Water Air Soil Pollut 225. https://doi.org/10.1007/s11270-­014-­1967-­0 Zhang M, Gao B, Yao Y et  al (2012) Synthesis of porous MgO-biochar nanocomposites for removal of phosphate and nitrate from aqueous solutions. Chem Eng J 210:26–32. https://doi. org/10.1016/j.cej.2012.08.052