Properties and Uses of Vegetable Oils 1536192074, 9781536192070

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FOOD SCIENCE AND TECHNOLOGY

PROPERTIES AND USES OF VEGETABLE OILS

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FOOD SCIENCE AND TECHNOLOGY

PROPERTIES AND USES OF VEGETABLE OILS

YASHVIR SINGH AND

NISHANT KR. SINGH EDITORS

Copyright © 2021 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. We have partnered with Copyright Clearance Center to make it easy for you to obtain permissions to reuse content from this publication. Simply navigate to this publication’s page on Nova’s website and locate the “Get Permission” button below the title description. This button is linked directly to the title’s permission page on copyright.com. Alternatively, you can visit copyright.com and search by title, ISBN, or ISSN. For further questions about using the service on copyright.com, please contact: Copyright Clearance Center Phone: +1-(978) 750-8400 Fax: +1-(978) 750-4470

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Library of Congress Cataloging-in-Publication Data Names: Singh, Yashvir, editor. | Singh, Nishant Kr. (Nishant Kumar), editor. Title: Properties and uses of vegetable oils / Yashvir Singh (editor), Department of Mechanical Engineering, Graphic Era University, Dehradun, Uttarakhand, India, Nishant Kr. Singh (editor). Description: New York : Nova Science Publishers, 2021. | Series: Food science and technology | Includes bibliographical references and index. Identifiers: LCCN 2021003210 (print) | LCCN 2021003211 (ebook) | ISBN 9781536192070 (hardcover) | ISBN 9781536192452 (adobe pdf) Subjects: LCSH: Vegetable oils. | Lubricating oils. | Vegetable oils as fuel. Classification: LCC TP680 .P76 2021 (print) | LCC TP680 (ebook) | DDC 665/.3--dc23 LC record available at https://lccn.loc.gov/2021003210 LC ebook record available at https://lccn.loc.gov/2021003211

Published by Nova Science Publishers, Inc. † New York

CONTENTS Preface Chapter 1

Chapter 2

Chapter 3

vii Lubrication Performance of Vegetable Oil-Based Nanofluids Under Different Lubrication Regimes Anil Dhanola and H. C. Garg Putranjiva Roxburghii: A Novel Feedstock as a Bio-Based Lubricant with MoS2 Nanoparticles Effect and Tribological Analysis Yashvir Singh and Nishant Kumar Singh Application of Nanoparticles to Vegetable Oil for Improved Thermal Mechanical Properties Anupama Mogha

Chapter 4

Potential Health Benefits of Vegetable Oils Amandeep Singh, Muskaan Kamboj and Shilpi Ahluwalia

Chapter 5

Vegetable Oils as an Alternate Source of Heat Storage Material Vishal Dabra

1

43

55 79

101

vi Chapter 6

Contents Used Vegetable Oil: Its Properties, Conversion Technologies, and Challenges as a Transportation Fuel Tavayogeshwary Thangadurai and Ching Thian Tye

117

Chapter 7

Biofuel and Fuel Characterization for IC Engines P. S. Ranjit, Venkateswarlu Chintala, A. Veeresh Babu and Yashvir Singh

145

Chapter 8

Jatropha Curcas P. S. Ranjit, Venkateswarlu Chintala, A. Veeresh Babu and Yashvir Singh

161

Chapter 9

Experimental Investigations on Influence of Preheating the Jatropha Based Straight Vegetable Oil Through Exhaust Gas Framework on an IDI CI Engine P. S. Ranjit, Venkateswarlu Chintala, A. Veeresh Babu and Yashvir Singh

Chapter 10

Cashew Nut Shell Oil: A Versatile by-Product of Cashew Industry Bharat Dholakiya and Smita Jauhari

177

197

About the Editors

293

Index

295

PREFACE Vegetable oils are a group of fats derived from seeds, nuts, cereal grains, and fruits. It is important to understand that not all vegetable oils are liquid oils at ambient temperatures. Vegetable oils have enormous potential as alternatives for mineral oil in a myriad of industrial applications. Although our knowledge of the genes and biochemical pathways leading to the formation of plant oils allows for the potential to engineer a diverse array of lipid products in seed oils, this goal remains a challenge. This book identifies the prospects of vegetable oils for different applications that facilitate readers from academia, industry, and research laboratories to enhance their knowledge of utilizing vegetable oils in different industrial sectors. Chapter 1 - The detrimental impact of conventional lubricants due to improper disposal and spillage on the ecological system lead to environmental and industrial concerns. In recent years, biodegradable lubricants prepared from vegetable oils have gained much popularity due to superior biodegradability and lubricity. However, poor thermo-oxidation properties restrict their potential use for industrial applications. Dispersion of suitable nanoparticles as an additive has been considered as a wellestablished practice for improving thermo-oxidation properties as well as tribological properties. The present chapter provides a comprehensive discussion of researches carried out in vegetable oil-based nanofluids

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under different lubrication regimes. Moreover, the lubrication mechanisms involved with nanofluids to enhance the tribological properties are also discussed. Additionally, the recent progress on other important properties such as dispersion stability, thermal properties, and rheological behaviour of vegetable oil-based nanofluids is presented. Finally, challenges and future directions are also discussed for vegetable oil-based nanofluids as sustainable lubricants. Chapter 2 - In this study, the tribological characterization of the Putranjiva oil was analyzed with the effect of MoS2 nanoparticles. The test was performed on a pin on disc tribometer by considering different conditions. Based on the specific concentration (percent) of nanoparticles, nano lubricants were properly dispersed through the ultrasonication process. In light of the investigation, a 0.5% concentration of MoS2 nanoparticles demonstrated a decrease in coefficient of friction and wear rate. The SEM images also show better surfaces when the nanoparticle was added up to 0.5% concentration which was due to the adhesion effect. The optimum addition was found at 0.5% concentration to the base oil. Chapter 3 - Increased environmental concerns and declining fossil fuels force one to move on to a more natural and renewable resource source. Vegetable processing in various processes instead of renewable mining oil resources has been initiated. The beauty and effectiveness of vegetable oils make them potential candidates to replace renewable resources. They are non-toxic, cost-effective and environmentally friendly and their products simply reduce the risk of harm to the human and the environment. Vegetable oils find many applications in the field of biomedical, polymer and paint industry and varnishes. With the incorporation of nanoscale particles or nanofiller the utilization and properties of vegetable oils can be improved to achieve higher mechanical and thermal properties. Chapter 4 - Oil derived from plants has been used for food-based applications all around the world. Plant oils have a varied range of fatty acids and being a non-polluting renewable resource, they are extensively used for industrial applications. Fatty acids (FAs) play a significant role in human nutrition which includes growth and development of human

Preface

ix

embryo, brain function and safeguard our body against many serious diseases such as cardiovascular, cancer, inflammation etc. Vegetable oils consist of important fatty acids like saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) and their fatty acid composition varies with the source plant and technology used during their manufacturing process. Thus, vegetable oils confer unique physico-chemical properties which make them extremely useful. In this chapter the source, composition, nutritional value, and health benefits of various vegetable oils have been discussed. Chapter 5 - Energy consumption has been accelerated from the past few decades, which can create an energy crisis in the upcoming years. Researchers have to look for the finest alternative to lessen the energy crisis within the least time. Heat storage materials (HSMs) have become popular in the last two decades to compensate the energy supply. Vegetable oil-based heat storage materials are a gift given by nature and possess the potential to serve in different applications. It also has the ability to substitute the existing toxic and expensive heat storage materials. This study emphasizes on need, types, properties, and the extraction processes of vegetable oils. Also, vegetable oils-based heat storage materials have been elaborated along with their major challenges associated with them. In this chapter, several research scopes are also proposed for future research work. The summary presumes that vegetable oil-based heat storage materials are one of the best heat storage materials for different applications. It works efficiently with renewable energy-based systems and also helps to recover waste heat from different heat-generating systems. Chapter 6 - Rising demand for energy has spurred the search of alternative resources for renewable and sustainable fuel. Vegetable oil is one of the potential sources of hydrocarbons to be converted into transportation fuel. In order to avoid the competition with fresh edible oils in the food supply, used vegetable oil that is widely available and economical has caught the attention of researchers. There are some issues with the properties of the used vegetable oil which make it impossible to be directly used as a transportation fuel. Those properties, such as

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viscosity, heating value, oxygen content and cold flow, if not treated, are unfavourable to meet fuel requirements. This chapter discusses the properties of used vegetable oil and the processes involved to modify their properties as required for standard transportation fuel as well as the challenges encountered for the biofuel produced. Chapter 7 - Various low emission situations have exhibited that the objectives of the Kyoto Protocol cannot be accomplished without giving an enormous job to biofuels by 2050 in the worldwide energy economy. Among the reasons why biofuels are suitable for such progress, one may recognize: (i) their straightforwardness; (ii) their creation through notable agrarian innovations; (iii) their potential for alleviation of atmosphere warming without complete rebuilding of the current working energy framework; (iv) the utilization of existing engines for their transportation (in any event, considering the customary turbofan utilized in avionics); (v) their capability to encourage the overall activation around a typical arrangement of guidelines; (vi) their potential as a legitimately accessible energy source with great open acknowledgement; (vii) their more uniform dispersion than the appropriations of petroleum derivative and atomic assets; and (viii) their capability to make benefits in country zones, including business creation. Chapter 8 - Jatropha Curcas is generally called as Jatropha. Oil extracted from Jatropha can be considered as a non-edible oil and can be yielded in a barren land with low water availability. Even the Indian Government also promoted this Jatropha derived oil as one of the promising alternatives for fossil fuels. Being Jatropha is a sustainable yield, environmentally friendly, good in yield different aspects in making use of alternative fuel as processing its seeds, composition, quality and advanced techniques has been discussed in the chapter. Chapter 9 - Depletion of fossil fuels, an exponential increase in the price of barrel crude oil, engine-out emissions reached to an alarming level, to promote local employment at the rural level, and to fulfil the words (Self -reliance) of the honourable prime minister of India. For sustainable development, an experimental investigation was done on Jatropha Curcas based preheated Straight vegetable Oil. In-direct Injection

Preface

xi

CI engine was selected, being most commonly used by the farmers in agricultural land. Performance parameters like Brake Thermal Efficiency (BTE), Brake Specific Energy Consumption (BSEC), Combustion Characteristics like P- Theta, Differential Heat Release Rate (DHRR), Integral Heat Release Rate (IHRR) and Emissions like NOx, CO, CO2, HC and Smoke were evaluated and presented in this chapter for suitability to make use in internal combustion engines. Chapter 10 - A cashew nut shell oil (CNSO) is a versatile by-product of the cashew industry. The cashew nut has a shell of about 1/8-inch thickness inside which is a soft honeycomb structure containing a dark reddish-brown viscous liquid called cashew nut shell oil, which is the pericarp fluid of the cashew nut. It is often considered as the better and cheaper raw material for the synthesis of various industrially important polymers. CNSO is a renewable and reliable feedstock as a replacement for existing non-renewable petrochemical feedstock. CNSO has innumerable applications in polymer-based industries such as friction linings, paints, and varnishes, laminating resins, rubber compounding resins, cashew cement, polyurethane-based polymers, surfactants, epoxy resins, foundry chemicals and intermediates for the chemical industry. It offers much scope and varied opportunities for the development of tailor-made polymers.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 1

LUBRICATION PERFORMANCE OF VEGETABLE OIL-BASED NANOFLUIDS UNDER DIFFERENT LUBRICATION REGIMES Anil Dhanola and H. C. Garg Tribology Laboratory, Department of Mechanical Engineering, Guru Jambheshwar University of Science and Technology, Hisar, Haryana, India

ABSTRACT The detrimental impact of conventional lubricants due to improper disposal and spillage on the ecological system lead to environmental and industrial concerns. In recent years, biodegradable lubricants prepared from vegetable oils have gained much popularity due to superior biodegradability and lubricity. However, poor thermo-oxidation properties restrict their potential use for industrial applications. Dispersion of suitable nanoparticles as an additive has been considered as a well-established practice for improving thermo-oxidation properties as well as tribological properties. The present chapter provides a 

Corresponding Author’s E-mail: [email protected].

2

Anil Dhanola and H. C. Garg comprehensive discussion of researches carried out in vegetable oil-based nanofluids under different lubrication regimes. Moreover, the lubrication mechanisms involved with nanofluids to enhance the tribological properties are also discussed. Additionally, the recent progress on other important properties such as dispersion stability, thermal properties, and rheological behaviour of vegetable oil-based nanofluids is presented. Finally, challenges and future directions are also discussed for vegetable oil-based nanofluids as sustainable lubricants.

INTRODUCTION The involvement of lubricants between the tribo-pairs is necessary for appropriate and constant operation of mechanical machines. Lubricants are served for various purposes, (a) to reduce friction and wear of interacting surfaces, (b) removal of heat, (c) protection from corrosion and oxidation, (d) act as a sealing agent against water, dust, and water. Lubricants can be classified into various forms, such as liquid lubricants, solid lubricant, and gaseous lubricant, but the demand for liquid lubricants is huge for industrial and automotive applications. During the refining of crude oil with the aim to extract gasoline as a fuel, another by-product in the form of mineral oil is also produced. According to the market survey, it is stated that most of the lubricants which are being used are mineral-based. These lubricants possess excellent thermal and physical properties. In general, lubricants are produced in combination with base stock and additives. The base stock includes basic fundamental properties, while additives contribute to enhance the existing properties of the base stock. World demand for lubricants is increasing by 2% annually from the last decade, and the demand was approximately 45.4 million metric tons in 2019 [1]. Automotive and industrial sectors have been using petroleum oil-based lubricants for almost a hundred years. The rapid demand for such lubricants indicates the depletion of mineral oil resources with increasing crude oil prices, and also growing a serious threat to our ecosystem as they are non-biodegradable and toxic. It is stated that almost 50% of consumed lubricants across the world end up into the environment because of spills, improper disposal, accident, etc. [2], and in which more than 95% of

Lubrication Performance of Vegetable Oil-Based Nanofluids …

3

lubricants are related to petroleum products. Used non-biodegradable lubricants contaminates the air, soil, water, and affecting human life and plant life on a large scale [3]. Hence, keeping these issues in view, there is an urgent need to replace the non-biodegradable lubricants to environmentally friendly lubricants. Over the last few decades, vegetable oils have also been using for nonedible purposes, such as biodegradable lubricants. The reasons for adopting vegetable oils as an alternative to petroleum-based lubricants are that they are considered as green lubricants and have less toxicity. Moreover, they possess several important characteristics that a common lubricant possesses, such as high lubricity, high viscosity indices, high flash point, etc. [4-6]. Despite such impressive properties, vegetable oils have some demerits like low oxidation stability at elevated temperature, poor low-temperature behaviour, etc. However, these issues can be minimized by the chemical modification of vegetable oils and the blending of additives in form anti-oxidants. Some of common chemical modification methods include transesterification and epoxidation [7]. Several studies available in the literature reveals that the vegetable oils have a strong potential to enhance the tribo-performance of contacting surfaces [4, 8]. Nowadays, dispersion of nanoparticles as additives into base oil has become a key research interest to the researchers [9, 10]. These additives improve not only tribological characteristics of base oil but also other properties such as thermal stability, thermal conductivity, viscosity, density, specific heat, pour point, fire point, etc. [11, 12]. The rise in viscosity and thermal conductivity increase the load-carrying capacity and rate of cooling, respectively, while high pour point and high fire point improve low and high temperature properties. This chapter provides an upto-date overview of research performed in the field of vegetable oil-based nanofluids under different lubrication regimes. Further, a review of other important properties, such as dispersion stability, rheological behaviour, etc. is also summarized. It is expected that the chapter will provide an insightful overview of recent progress in vegetable oil-based nanofluids, and will encourage the tribologists and researchers to do more research work in field of green lubricants.

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Anil Dhanola and H. C. Garg

CLASSIFICATION OF LUBRICANTS AND LUBRICATION REGIMES Lubricants perform a vital role and work as a mediator between two contacting surfaces to reduce friction and wear, and to diminish the heat generated between the contacts. The generated lubricant film between the contact helps to reduce metal-to-metal contact. High viscosity index, high flash point, low pour point, high resistance to corrosion, and high thermooxidation stability are the key characteristics of a common lubricant to perform efficiently, especially at severe conditions. Often, lubricants are categorized based on their physical appearance, resources, and applications. A detailed classification can be seen in Figure 1 [13]. Lubricants perform under three different lubrication regimes, namely boundary lubrication, mixed lubrication, and hydrodynamic lubrication. The concept of these lubrication regimes can be understood from Figure 2, which is known as the Stribeck curve [14]. This curve is widely applicable to examine the lubrication performance. As shown in the figure, the friction coefficient between the tribo-pairs changes with the Hersey 𝑉𝑖𝑠𝑐𝑜𝑠𝑖𝑡𝑦×𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 ). 𝑙𝑜𝑎𝑑

number (

A film is developed between the pairs by

applying a lubricant. If the lubricant is more viscous, then the developed film would be thicker, while less viscous lubricants develop a thinner film. If the fluid film thickness is more than the surface roughness values of the tribo-pairs, it means the tribo-pairs are successfully separated by the lubricant, which result in lower friction. This situation comes under the hydrodynamic lubrication regime. Further, when the asperities of the tribopairs come closer, there is a chance of high friction, and consequently surface wear occurs. That mostly happens when the Hersey number reduces. This regime is called as boundary lubrication. The mixed lubrication regime lies between the boundary and hydrodynamic lubricant regimes. The main differences between the regimes are tabulated in Table 1.

Figure 1. Classification of lubricants [13].

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Anil Dhanola and H. C. Garg

Figure 2. Stribeck curve [14].

Table 1. Differences between lubricant regimes [15] Regime

Hm (μm)

Dry Boundary

0.001-0.01 0.001-0.05

Friction coefficient 0.4-0.8 0.08-0.3

Mixed

0.1-1

0.03-0.1

Hydrodynamic

1-100

0.007-0.01

Film formation No lubricant Lubricants reacts with contact Lubricant dragged into contact Lubricant dragged into contact

Contact geometry Variable Variable Counterformal Conformal

VEGETABLE OILS AS ALTERNATIVE LUBRICANT BASE STOCKS Before the invention of petroleum-based lubricants, in ancient times, vegetable oils were widely used for lubrication purposes like in machines and transportation. After the development of petroleum lubricants, the use of vegetable oil quickly reduced as petroleum products were relatively cheap and had good properties. Nowadays, with depleting petroleum reserves and increasing environmental concerns, the use of vegetable oils as lubricants is making a comeback.

Lubrication Performance of Vegetable Oil-Based Nanofluids …

7

Table 2. Thermal and physical properties of vegetable oils [7] Vegetable oils

Density (Kg/m3)

Jatropha (non-edible) Karanja (non-edible) Palm (edible) Mahua (non-edible) Sunflower (edible) Coconut (edible) Soybean (edible) Neem (non-edible) Castor (non-edible) Linseed (edible) Olive (edible) Peanut (edible) Tobacco (non-edible) Rapeseed (edible) Rice bran (edible)

878 918 875 850 878 805 885 885 898 890 892 882 887 880 886

Kinematic viscosity at 40oC (mm2/sec) 4.82 4.80 5.72 3.40 4.45 2.75 4.05 5.20 15.25 3.74 4.52 4.92 4.25 4.45 4.95

Oxidation stability at 110oC (Hrs.) 2.3 6.0 4.0 0.9 35.4 2.1 7.2 1.2 0.2 3.4 2.1 0.8 7.5 0.5

Cloud point oC

Flash Point oC

2.75 9.0 13.0 3.42 0 1.0 14.5 -13.5 -3.8 5.0 -3.3 0.3

136 150 165 210 185 112 176 44 260 178 179 177 166 62 -

Table 3. Applications of vegetable oils [13] Vegetable oils Canola (edible) Castor (non-edible) Coconut (edible) Olive (edible) Palm (edible) Rapeseed (edible) Sunflower (edible) Linseed (edible) Soybean (edible) Jojoba (non-edible) Tallow (non-edible)

Applications Hydraulic oils, transmission fluids, metalworking fluids, chain bar lubes, etc. Gear lubricants, greases, etc. Gas engine oils Automotive lubricants. Rolling lubricants, greases, etc. Chain bar saw lubricants, biodegradable greases, etc. Grease, diesel fuel substitutes, etc. Coating, paints, etc. Lubricants, bio-diesel fuels, hydraulic oils, etc. Grease and lubricant applications. Steam cylinder oils, lubricants, soaps, etc.

Vegetable oils are promising substitute of conventional mineral oils in terms of biodegradability and other impressive properties like high viscosity indices, high flash point, excellent lubricity, etc. In general,

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vegetable oils are categorized into two forms: edible and non-edible oils. Some of the physical and chemical properties and applications of edible and non-edible oils are listed in Table 2 and Table 3, respectively. The vegetable oils are mainly composed of triacylglycerols (Approx. 98%) and different fatty acid molecules. Vegetable oils are also contained some minor compositions of diglycerol (0.5%), free fatty acids (0.1%), sterols (0.3%), and tocopherols (0.1%) [16]. As Figure 3 depicts, the triglyceride structure made of three hydroxyl groups esterified with carboxyl groups of fatty acids. The high molecular weight of esters presented in triglyceride structure provides high viscosity properties and volatility. The triglyceride structure also helps to protect these esters against a certain temperature range. A structure having large amounts of saturated long-chain fatty acids exhibits poor low-temperature behaviour while structure having large amounts of certain polyunsaturated fatty acids exhibits unfavorable oxidation behaviour and surrender at high temperature. Poor thermo-oxidation stability (due to the presence of bisallylic protons) is the main disadvantage of vegetable oils as they get oxidized over 80oC. However, there are some potential solutions to mitigate this issue such as addition of suitable anti-oxidants, chemical modification of raw vegetable oils via transesterification and epoxidation, etc. To date, researchers have put a lot of efforts to make vegetable oils as sustainable, biodegradable lubricants, some of the findings are summarized in Table 4.

Figure 3. Structure of Triglyceride.

Palm oil

Sunflower, soybean, jatropha and waste oils

Oxidation measurement tester [Model:743 Rancimat] Thermogravimetric method

Palm oil

Syahrullail et al. [23] Shomchoam and Yoosuk [24]

Attia et al. [25]

Four-ball tribometer

Rapeseed, olive and lard oils Coconut, sesame and sunflower oils

Gryglewicz et al. [21] Jayadas and Nair [22] Four-ball tribometer

Gas chromatography

Soybean oil

Soybean oil

Cannonfenske capillary viscometer and micro oxidation tester Micro oxidation tester and pour point tester -

Soybean and sunflower oils

Hwang and Erhan [19] Ruger et al. [20]

-

Rapeseed oil

Becker and Knorr [17] Erhan and Asadauskas [18]

Testing equipment

Vegetable oils

Author (s)

Transesterification

Hydrogenation

-

-

Tertiarybutylhydroquinone (anti-oxidant) Transesterification

Epoxidation

Additives/chemical modification Zinc dimethyldithiocarbamate (antioxidant) -

Jatropha oil had the lowest pour point and highest viscosity index, and good thermal stability (225 oC)

Selected anti-oxidant found suitable for rapeseed oil. It was confirmed that the selected oils had lower oxidation stability and a higher pour point with respect to the mineral oil. Oxidation stability increased, and pour point decreased remarkably. Selected anti-oxidant significantly controlled the viscosity at the high-temperature range. Esters produced from olive oil had higher thermo-oxidation stability. Coconut oil had the highest pour point, and it can be reduced by suitable additives or chemical modification Greater wear scar diameter was obtained, thus suggested to add appropriate additives. Oxidation stability was improved significantly.

Findings

Table 4. Summary of the research carried out by the researchers on vegetable oils

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Anil Dhanola and H. C. Garg

NANOPARTICLES AS LUBRICANT ADDITIVE AND THEIR CLASSIFICATION Base lubricants play a vital role in lubricating the tribo-pairs, separate the sliding contacts, removal of heat, and reducing friction and wear. However, base lubricant cannot perform effectively solely at severe operating conditions; therefore, there is a need of appropriate additives to improve the base lubricant properties, for example, oxidation stability, anti-friction, anti-wear, and anti-corrosion. Zinc-dialkyldithiophosphate (ZDDP) is the most commonly used anti-wear additives, which has been used widely for many years due to its characteristics in reacting with metal surfaces and forming a protective tribo-film. However, as far as environmental concern, ZDDP is not biodegradable and is highly toxic. Therefore, researchers are trying to find-out environmentally-friendly alternatives additives.

Figure 4. Classification of nanoparticles for lubricating oils.

Lubrication Performance of Vegetable Oil-Based Nanofluids …

11

Nanoparticles as lubricant additives have gained much interest over the last few decades. Nanoparticles have a nanometer size range, which allows them to fill the gaps between the contact asperities and form a protective tribo-film. High thermal conductivity is the additional feature of nanoparticles, which helps to release the heat generated between the contacting surfaces. Moreover, lubricants containing nanoparticles do not need of tribo-chemical elements. The use of nanoparticles has gained much interest in intensifying the characteristics of bio-based lubricants. As per the environmental concern, most nanoparticles are cleaner and have less toxicity. Figure 4 shows the general classification of nanoparticles for lubricating oils.

LUBRICATING MECHANISMS ASSOCIATED WITH USING NANOPARTICLES IN NANOFLUIDS Some lubricating mechanisms are associated with lubricating oils containing nanoparticles for reducing rate of friction and wear. As Figure 5 depicts, these mechanisms can be classified into four types that include rolling effect (Figure 5 (a)), mending effect (Figure 5 (b)), protective film effect (Figure 5 (c)) and polishing effect (Figure 5 (d)). 



Rolling effect or ball bearing effect: In this effect, nanoparticles act like ball bearings and entertain between the contacting surfaces. This effect is generally applied for the spherical or near-spherical nanoparticles. The rolling effect can only be achieved at lower loading conditions as there is a change to be disturbed nanoparticles shape at higher load. Mending effect or self-repairing effect: In this effect, nanoparticles act as a deposition agent, in which nanoparticles are deposited over the scratches, scars, and filled the rooves and tiny cavities present in the mating surfaces. Ultimately, this effect enhances the surface properties. The energy-dispersive X-ray spectroscopy (EDS)

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Anil Dhanola and H. C. Garg





technique is commonly used for the confirmation of the mending effect. Protective film formation effect or tribo-film effect: Higher colloidal stability of nanolubricants can form a thin film on tribopairs, and this film has dense nature and low shear, which results in avoiding meta-to-metal contact. Scanning electron microscopy (SEM)/EDS, Raman spectroscopy, etc. are the common instruments by which this effect can be verified. Polishing effect or smoothing effect: This effect enhances the surface quality by minimizing the surface roughness of the friction-pairs. During the operation, hard nanoparticles in the lubricating oil act as a polishing tool, which helps to reduce the surface roughness of the rubbing surface.

Figure 5. Nanolubrication mechanisms.

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13

STUDIES ON PERFORMANCE OF VEGETABLE OIL-BASED NANOFLUIDS IN DIFFERENT LUBRICATION REGIMES During the past few years, a lot of research has been conducted on tribo-performance of vegetable oil-based nanofluids under boundary, mixed lubrication regimes. The triglycerides structure of vegetable oil has long chains of polar fatty acids, which make them suitable for working in boundary lubrication. Consequently, high strength of protecting film of lubricant is formed on the surfaces and helps to reduce friction and wear. Thottackkad et al. [26] studied the tribo-behaviour of coconut oil (CO) at different proportions of copper oxide (CuO) nanoadditives using a pinon-disc tribometer. The outcomes showed that the coefficient of friction and wear rate was found minimum at 0.34 wt. % of CuO nanoparticles, and wear scar using nanolubricants was less than the raw coconut oil. Also, the dispersion analysis results revealed that the CO with CuO nanoparticles was not preferable for large stationary applications. Alves et al. [6] studied comparative tribo-performance of chemically modified soybean oil, sunflower oil, and conventional lubricant containing CuO and zinc oxide (ZnO) nanoparticles using a high-frequency reciprocating test rig in boundary lubrication. The authors reported that the anti-wear characteristics of oxide nanoparticles highly depend on the base fluid. For biolubricant, using nanoparticles didn’t show any significant improvement in reducing the wear than the conventional lubricant. Reeves et al. [27] studied the influence of particle size of boron nitride (hBN) (70nm, 0.5, 1.5 and 5.0 μm) on tribological characteristics of canola oil by a pin-on-disc tribotester. The results stated that 70 nm hBN particles offered better tribological performance than micro-sized particles in canola oil. These nanoparticles amalgamated in asperities valleys of surface and formed a protective thin film, which improves the tribological performance of canola oil. Xu et al. [28] studied the morphological effect of molybdenum disulfide (MoS2) on the tribo-performance of rapeseed oil by a four-ball tester. The results revealed that the MoS2 nanoparticles significantly enhance the wear resistivity of the rapeseed oil. However, nano-platelets

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Anil Dhanola and H. C. Garg

and micro-platelets not showed any wear resistance in rapeseed oil due to their poor dispersion stability. Zen and Rashmi [29] examined the tribological characteristics of two different biolubricant (i.e., TMP ester obtained from palm oil and the mixture of trimethylolpropane (TMP) ester (20%) and palm cooking oil (80%)) using nano graphene platelets (NGPs) in a four-ball tester machine. The results proved that the TMP ester with NGPs helped to minimize the friction coefficient by 10%, whereas 17% reduction found in the mixture of TMP ester and palm cooking oil. But at the higher temperature, these oils didn’t show good lubricating properties due to the failure of the protective film between the sliding contacts. Zulkifli et al. [30] examined the tribo-performance of palm oil-based trimethylolpropane (TMP) ester oil under different lubrication regimes using a four-ball tribotester machine. Tests were conducted under different loading conditions at room temperature. The outcomes stated that the addition of TMP ester (up to 3 %) in a conventional oil reduced the wear scar diameter and friction coefficient by 30% under boundary lubrication. In contrast, in hydrodynamic lubrication, the addition of TMP ester of 7 % minimized the friction by 50%. Arumugam and Sriram [31] studied the comparative study of chemically modified rapeseed oil using TiO2 nanoadditives and microaddtives using a pin-on-disc tribotester. The observed results stated that the TiO2 nanoadditives improved the tribological properties more than with and without microscale TiO2 additives in chemically modified rapeseed oil. The authors also recommended TiO2 nanoadditives as an anti-wear additive. Gu et al. [32] studied the tribological characteristics of rapeseed oil with SA/Ce-TiO2 nanoparticles using a four-ball tribotester. SA/Ce-TiO2 nanoparticles were developed by the sol-gel technique, and the surface of particles was modified with stearic acid. Their results revealed that SA/Ce-TiO2 additives could improve the anti-friction and anti-wear properties of the rapeseed oil. The optimum friction reduction anti-wear properties were found for SA/Ce-TiO2, when it doped with 3 and 2% of stearic acid. Arumugam and Sriram [33] studied the tribo-performance of chemically modified rapeseed oil with different Cuo nanoparticles concentration using high-frequency reciprocating tribotester. The results revealed that CuO

Lubrication Performance of Vegetable Oil-Based Nanofluids …

15

nanoparticles effectively improved the tribo-performance of chemically modified rapeseed oil, especially at the optimum concentration (0.5 wt. %). It was also observed from the AFM and SEM analysis that the cylinder liner surface was smooth at the optimal proportion of CuO nanoadditives in chemically modified rapeseed oil. Mahipal et al. [34] studied the influence on tribological characteristics of ZDDP (Zinc- dialkyl-dithiophosphate) nano-additives in Karanja oil using four-ball tester and compared with conventional oil (SAE20W40). The tribological results revealed that Karanja oil with ZDDP showed better properties with decreasing friction coefficient and wear scar diameter compared with conventional oil. Physical and chemical properties also found greater than conventional oil. Gu et al. [35] studied the tribo-behaviour of rapeseed oil with OA/La-TiO2 nanoparticles using a four-ball tribotester machine and wear tester machine. La-TiO2 nanoparticles were developed by the sol-gel technique, and the surface was modified by the oleic acid. The surface characterization of OA/La-TiO2 nanoparticles was measured by scanning electron microscopy and found 20 nm average sizes of nanoparticles. Tribological results showed that OA/La-TiO2 nanoparticles were capable in enhancing the load-carrying capacity, anti-friction, and anti-wear properties of rapeseed oil. Zhao et al. [36] studied tribo-characteristics of sunflower oil with zinc borate ultrafine powder (ZBUP) on pin-on-disc and four-ball tribotester. Surface characterizations of worn surfaces were investigated using atomic force microscopy (AFM) and SEM. The results showed that the ZBUP nanoparticles exhibited superior tribological properties, especially with 0.5 wt% ZBUP concentration with the base oil, the friction coefficient and wear scar diameter were found reduced by 14% and 10%, respectively. Koshy et al. [37] examined the tribo-performance of coconut oil-based biolubricants with molybdenum disulphide (MoS2) nanoparticles and compared them with the mineral oil using modified pinon-disc tribotester and four-ball tester in boundary lubrication regime. Response surface methodology and ANOVA techniques were used to formulating the data. The obtained outcomes presented that the coconut oil with MoS2 nanoparticles notably reduced the friction and wear in comparison to the mineral oil, and this reduction in wear and friction

16

Anil Dhanola and H. C. Garg

achieved with increasing concentration till the optimum concentration of 0.53% in coconut oil is not reached. Gulzar et al. [38] investigated the tribological performance of chemically modified palm oil with molybdenum disulfide (MoS2) and CuO nanoparticles as anti-wear and extreme pressure using four-ball tester. Surface characterization of worn surfaces was done by scanning electron microscope (SEM) and energydispersive X-ray (EDX) and micro-Raman scattering spectroscopy. The results revealed that the MoS2 and CuO nanoparticles effectively improved the anti-wear and extreme pressure properties of chemically modified palm oil. Uniform dispersion stability and anti-wear and extreme pressure properties found more with MoS2 than CuO nanoparticles in chemically modified palm oil. Gulzar et al. [39] investigated the tribological performance of chemically modified jatropha oil with tungsten disulfide (WS2) nanoparticles using a four-ball tester. Surface characterization of worn surfaces was examined by scanning electron microscope (SEM) and energy-dispersive X-ray (EDX). The results showed that the WS2 nanoparticles acted as good anti-wear and extreme pressure additives in chemically modified jatropha oil and showed better friction and wear reduction than virgin chemically modified jatropha oil. Zainal et al. [40] studied the tribological characteristics of bio-based lubricant (palm oilbased TMP ester PAO) with calcium carbonate (CaCO3) nanoadditives using four-ball tribotester. CaCO3 nanoadditives were processed from cockle shells. The results showed that the tribo-performance of bio-based lubricants significantly improved at each concentration of CaCO3 nanoparticles, but optimum concentration found at 8 wt. % of CaCO3 nanoparticles. Su et al. [41] investigated the tribological performance of graphite nanoparticles in LB2000 vegetable oil using a pin-on-disc tribotester. Field emission SEM and EDX were used for surface characterization of worn surfaces. The results revealed that the graphite nanoparticles remarkably increased the performance of LB2000 vegetable oil in terms of reduction in friction and wear and also surface found smooth using nanoparticles than using pure LB2000 vegetable oil. Baskar et al. [42] studied the tribo-behaviour of chemical modified rapeseed oil with CuO, WS2, and TiO2 nanoparticles using a four-ball tester and then

Lubrication Performance of Vegetable Oil-Based Nanofluids …

17

compared with synthetic lubricant. The results revealed that the friction coefficient of chemical modified rapeseed oil was found less with CuO as compared to WS2 and TiO2 nanoparticles and synthetic lubricants. In case of wear scar values, the same above trend was observed. Koshy et al. [43] studied the thermo-physical behaviour of two different vegetable oils (i.e., coconut oil and mustard oil) with CuO nanoadditives using modified pinon-disc tribotester. The results concluded that CuO nanoparticles improved the tribological performance of vegetable oils at higher temperatures. Also, the performance of coconut oil found better than mustard oil. Shaari et al. [44] studied the tribo-behaviour of palm oil containing TiO2 nanoadditives using a four-ball tester. Obtained results showed that tribo-performance of palm oil slightly improved with TiO2 nanoadditives from which TiO2 nanoadditives with 0.05 wt. % found optimum concentration than other concentrations. Kashyap and Harsha [45] examined the tribological behaviour of chemically modified rapeseed oil with the addition of CuO and CeO2 nanoadditives on a four-ball tribotester. The tribological results stated that the friction reduction properties of chemically modified rapeseed oil were improved with the addition of CuO and CeO2 nanoadditives, and anti-wear properties of chemically modified rapeseed oil were not impressive with CuO and CeO2 nanoadditives than synthetic oil. Also, tribological performance (wear scar diameter and coefficient of friction) of CeO2 nanoadditives in chemically modified rapeseed oil found superior than that of CuO nanoadditives. Azman et al. [46] investigated the tribo-performance of the mixture of trimethylolpropane (TMP) ester (5 vol. %) produced from palm oil and polyalphaolefin (95 vol. %) with the addition of graphene nanoplatelets using four-ball tribotester. The results stated that the graphene nanoplatelets improved the tribological properties of TMP ester (5 vol. %) + PAO (95 vol. %) than that of blank lubricant at the optimum concentration (0.005 wt. %). Also, the friction coefficient and wear scar diameter was reduced by 5 and 15%, respectively. Dispersion stability of graphene nanoplatelets was not found good, and graphene nanoplatelets were started settled down within two days. Gupta and Harsha [47] investigated the tribo-performance of castor oil containing calcium-copper-titanate nanoparticles (CCTO) and ZDDP

18

Anil Dhanola and H. C. Garg

using a four-ball tribotester. The results revealed that CCTO nanoparticles and ZDDP at 0.25 and 1.0 w/v%, respectively improved the extreme pressure and extreme wear properties of castor oil. However, the coefficient of friction was found better at 0.5 w/v% concentration of ZDDP additives, while CCTO nanoparticles showed the same level of characteristics at all concentrations. Baskar et al. [48] studied the tribobehaviour of chemically modified rapeseed oil with TiO2, WS2, and CuO nanoadditives in the various different journal bearing materials (i.e., brass, bronze, and copper) using a pin-on-disc tribometer. A mathematical model was developed by response surface methodology (RSM) for the analysis of the tribological performance of nano-based biolubricants. The results revealed that the friction coefficient and specific wear rate were found the minimum for bronze material lubricated with CuO nano-based biolubricant. Surface morphology was obtained using SEM and revealed that the worn surface of bronze material was smoother while lubricated with CuO nano-based biolubricant compared to other bearing materials. Kiu et al. [49] investigated the tribo-behaviour of vegetable oil containing graphene sheets (GN), carbon nanotubes (CNT) and graphene oxide (GO) using four-ball tribotester. The outcomes showed that the GN with 50 ppm exhibited low wear scar diameter and friction coefficient among other oil samples, including base oil, but further addition of GN impaired the friction and wear. Garg et al. [50] investigated the tribo-behaviour of chemically modified non-edible Karanja oil containing Cu nanoparticles and ZDDP under elastohydrodynamic regime using four-ball tribotester. The results stated that the Cu nanoparticles and ZDDP additives improved the tribological characteristics of base oil. Wear was reduced by 30% at 0.5 wt% concentration of ZDDP additives. In comparison, at the 0.5 wt% concentration of Cu nanoparticles, friction was decreased by 61% as compared to the base oil without additives, and it was observed from results that ZDDP act as an anti-wear additive. In contrast, Cu nanoparticles acted as anti-friction additives. Gupta et al. [51] examined the tribo-behaviour of epoxidized rapeseed oil with the addition of CuO, CeO2, and polytetrafluoroethylene (PTFE) nanoparticles using four-ball tribotester and then compared with unmodified rapeseed oil at same

Lubrication Performance of Vegetable Oil-Based Nanofluids …

19

nanoadditives concentrations. The results stated that the CuO nanoparticles impaired the anti-wear property of modified and unmodified rapeseed oil. However, CeO2 and PTFE nanoparticles significantly improved the antiwear property for unmodified rapeseed oil at 0.1% w/v concentration. The coefficient of friction was improved for all three nanoparticles at all concentrations in modified and unmodified rapeseed oil. Gupta and Harsha [52] investigated the tribological performance of castor oil containing surface-modified CuO nanoadditives under the boundary lubrication regime using a four-ball tribotester and then compared with paraffin oil. The results revealed that the wear scar diameters were reduced by 28.3 and 22.2% while the coefficient of frictions were decreased by 34.6 and 17.3% at optimum concentrations of surface-modified CuO nanoparticles in castor oil and paraffin oil, respectively. Gupta and Harsha [53] examined the tribological performance of epoxidized sunflower oil with the addition of CuO and CeO2 nanoparticles for steel/steel contacts using a four-ball tribotester and then compared with unmodified rapeseed oil at same nanoadditives concentration. The results exhibited that CeO2 nanoparticles showed good compatibility with modified and unmodified sunflower oil and reduced the wear scar diameter. 0.1% w/v concentration of CeO2 nanoparticles was found optimum in both bio-based oils due to having low wear scar diameter and low friction coefficient. In contrast, CuO impaired the anti-wear property of both bio-based oils. Gupta and Harsha [54] examined the tribological performance of castor oil containing CeO2 and polytetrafluoroethylene nanoparticles on a four-ball tribotester. The obtained results showed that the wear scar diameters were decreased by 37.4 and 35.3% at optimum concentrations of CeO2 and polytetrafluoroethylene nanoparticles (0.25 and 0.1% w/v, respectively). The coefficient of friction was significantly improved at all concentrations of polytetrafluoroethylene nanoparticles, but 0.5% w/v found the optimum. However, CeO2 showed the best anti-friction behaviour at 0.25% w/v concentration. Shafi et al. [55] examined the tribo-performance of avocado oil with Cu nanoparticles in boundary and mixed lubrication regimes for steel/alloys contacts using a pin-on-disc tribometer. The results stated that Cu nanoparticles improved the tribological characteristics of avocado oil.

20

Anil Dhanola and H. C. Garg

The friction coefficient was found minimum at 1 wt. % of Cu and minimum wear were found at 0.5 wt. % of Cu. Also, the SEM images stated that the inclusion of Cu nanoparticles in base oil lead the enhancement in surface properties when compared with base oil without additives and under dry sliding conditions. Talib and Rahim [56] examined the machining and tribo-behaviour of modified jatropha oils with and without hexagonal boron nitride (hBN) nanoparticles using NC lathe machine. The results revealed that the modified jatropha oil with a concentration of 0.05 wt. % of hBN exhibited excellent tribological properties and was found correlated in terms of good machining performance such as small cutting force, small cutting temperature, and small surface roughness with long life and less tool wear. Bhaumik et al. [57] evaluated the tribo-characteristics of castor oil with zinc oxide nanoparticles between steel-steel contacts using a four-ball tribotester. The observed results showed that the zinc oxide nanoparticles enhanced the tribological performance of castor oil up to 0.1 wt. % concentration of zinc oxide further increasing in zinc oxide concentrations, the deteriorations of contact surfaces were started. Kerni et al. [58] investigated the performance of chemically treated olive oil with the addition of copper and hexagonal-boron nitride nanoparticles in boundary and mixed lubrication regimes using a pin-on-disc tribo tester. LM 13 alloy /EN 31 friction pair was chosen for this study. The overall results show that 0.5wt. % was to be found optimum concentration in decreasing friction and wear characteristics. Also, during the use of raw olive oil, high surface damage of the tribo-pair was reported in comparison to the use of treated oils. Cortes and Ortega [59] investigated the characterization of coconut oil containing different proportions of CuO and silicon oxide (SiO2) using a customized tribometer for metal forming operations. Optimal concentrations of 0.5% and 1.25% were observed for CuO and SiO2, respectively. However, the least material loss and friction coefficient were to be observed during the use of coconut oil/SiO2 nanolubricants. Suresha et al. [60] studied the lubrication effects of non-edible vegetable oil (i.e., neem oil) containing graphene nanoplatelets (GNPs) using a four-ball tester. The authors found that the blending of GNPs within the neem oil is

Lubrication Performance of Vegetable Oil-Based Nanofluids …

21

found appropriate to reduce the friction coefficient and wear scar, and oil containing 1 wt. % GNPs showed the lowest friction coefficient and smoother wear scar diameter. Recently, Singh et al. [61] developed chemically treated moringa oleifera oil via the two-step transesterification process and then formulated nanolubricants by adding silicon carbide (SiC) within the modified oil to investigate their lubrication performance. The performance of the prepared lubricants was examined in pin-on-disc tribo tester under different operating parameters. Overall results showed that the 0.5% concentration of nanoparticles produced the least friction and wear. Moreover, during the use of virgin oil, maximum scratches were to be observed on the metal surface in comparison to modified oil/SiC nanolubricants. Kumar et al. [62] studied the tribo-performance of canola oil containing different weight fractions of CuO nanoparticles on steelsteel contacts using a pin-on-disc tribometer. They observed that blending of nanoparticles significantly improved the tribological characteristics of base lubricant by forming a protecting layer on the metal surface. Also, they found that the concentration 0.1 wt. % showed the least friction coefficient and specific wear rate among the other concentrations. The summary of the above literature is also presented in Table 5. The above discussion clearly shows that the lubrication performance of vegetable oil-based nanofluids has been widely explored under boundary and mixed lubrication regimes. As reported by various researchers, that boundary and hydrodynamic lubrication can be achieved using vegetable oils due to the presence of long-chain of fatty acids and polar groups [63, 64]. However, very few efforts have been made by the researchers under hydrodynamic lubrication regimes using vegetable oil-based lubricants or vegetable oil-based nanofluids. Durak et al. [65] formulated biodegradable lubricants by blending different proportions of sunflower oil to mineral oil and then tested in journal bearing at different temperatures. Results showed that base oil added with a small quantity of sunflower oil exhibited a lower friction coefficient, especially at lower operating conditions and temperature. Further, Durak [66] developed lubricating oils by adding different volume percent of rapeseed oil as an additive to SAE 20W50 for conducting experiments on journal bearing.

Thottackkad et al.

2012

2013

2013

2013

2013

[6]

[27]

[28]

[29]

Zen and Rashmi

Xu et al.

Reeves et al.

Alves et al.

Authors

Year

Ref. No. [26]

TMP ester obtained from palm oil and mixture of TMP ester (20%) and palm cooking oil (80%)

Rapeseed oil

Canola oil

Chemically modified soybean oil, Sunflower oil

Coconut oil

Base Fluids

Molybdenum disulfide (MoS2) Nanographene platelets (NGPs)

Boron nitride (hBN)

CuO and Zinc oxide (ZnO)

Copper oxide (CuO)

Nanoparticles

Four-ball tester

Four-ball tester

Pin-on-Disc

High-frequency reciprocating test rig

Experimental Setup Pin-on-Disc

1. COF and wear rate was found minimum at 0.34 wt% of CuO nanoparticles. 2. Wear scar diameter using nanolubricants was less than the raw coconut oil. 1. Anti-wear characteristics of oxide nanoparticles highly dependent on the base oil. 2. In the case of biolubricant with nanoparticles didn’t show any significant improvement to reduce the wear in comparison of conventional lubricant hBN particles (70 nm) offered better tribological performance than micro-sized particles in canola oil. MoS2 nanoparticles were significantly improved the wear resistance of the rapeseed oil. 1. TMP ester with NGPs helped to reduce the coefficient of friction by 10%, whereas 17% reduction was found in the mixture of TMP ester and palm cooking oil. 2. At higher temperatures these oils didn’t show good lubricating properties due to the failure of the protective film between the mating surfaces.

Major Findings

Table 5. Summary of tribological studies of vegetable oil-based nanolubricants

Zulkifli et al.

2013

2013

2014

2014

2014

2013

[31]

[32]

[33]

[34]

[35]

Gu et al.

Mahipal et al.

Arumugam and Sriram

Gu et al.

Arumugam and Sriram

Authors

Year

Ref. No. [30]

Rapeseed oil

Karanja oil

Chemically modified rapeseed oil

Rapeseed oil

Chemically modified rapeseed oil

TMP ester produced from palm oil

Base Fluids

OA/La-Tio2

ZDDP (Zinc- dialkyldithio-phosphate)

CuO

SA/Ce-Tio2

TiO2 nano and microparticles

-

Nanoparticles

Four-ball tester

Four-ball tester

High-frequency reciprocating tribotester

Four-ball tester

Pin-on-Disc

Experimental Setup Four-ball tester Some contents of TMP ester in an ordinary oil remarkably reduced the friction and wear scar diameter under both boundary and hydrodynamic lubrication regimes. 1. TiO2 nanoparticles improved the tribological properties more than with and without microscale TiO2 particles in chemically modified rapeseed oil. 2. TiO2 nanoparticles acted as an anti-wear additive. SA/Ce-TiO2 additives could improve the friction reduction and anti-wear properties of the rapeseed oil. CuO nanoparticles effectively improved the tribological performance of chemically modified rapeseed oil especially at an optimum concentration (0.5 wt%). Karanja oil with ZDDP showed better properties with decreasing coefficient of friction and wear scar diameter with respect of conventional oil. OA/La-Tio2 nanoparticles were capable of enhancing the load-carrying capacity, antifriction and anti-wear properties of rapeseed oil.

Major Findings

Zhao et al.

2014

2015

2015

2015

[37]

[38]

[39]

Gulzar et al.

Gulzar et al.

Koshy et al.

Authors

Year

Ref. No. [36]

Chemically modified jatropha oil

Chemically modified palm oil

coconut oil

Sunflower oil

Base Fluids

Tungsten disulfide (WS2)

MoS2 and CuO

Molybdenum disulphide (MoS2)

Zinc borate ultrafine powder (ZBUP)

Nanoparticles

Four-ball tester

Four-ball tester

Pin-on-Disc and Four-ball tester

Experimental Setup Pin-on-Disc and Four-ball tester

Table 5. (Continued)

ZBUP nanoparticles exhibited superior tribological properties especially with 0.5 wt% ZBUP concentration in the base oil, where friction coefficient and wear scar diameter was found to be reduced by 14% and 10%, respectively. Coconut oil with MoS2 nanoparticles significantly reduced the friction and wear compared to the mineral oil and this reduction in wear and friction achieved with increasing concentration till the optimum concentration of 0.53% in coconut oil. 1. MoS2 and CuO nanoparticles effectively improved the anti-wear and extreme pressure properties of chemically modified palm oil 2. Uniform dispersion stability and anti-wear and extreme pressure properties found more with MoS2 than CuO nanoparticles in chemically modified palm oil. WS2 nanoparticles acted as good anti-wear and extreme pressure additives in chemically modified jatropha oil and showed better friction and wear reduction than blank chemically modified jatropha oil.

Major Findings

Zainal et al.

2015

2015

2015

2015

2015

2016

[41]

[42]

[43]

[44]

[45]

Kashyap and Harsha

Shaari et al.

Koshy et al.

Baskar et al.

Su et al.

Authors

Year

Ref. No. [40]

Chemically modified rapeseed oil

Palm oil

Coconut oil and mustard oil

Chemically modified rapeseed oil

LB2000 vegetable oil

Palm oil- based TMP ester PAO

Base Fluids

CuO and cerium oxide (CeO2)

TiO2

CuO

CuO, WS2 and TiO2

Graphite

Calcium carbonate (CaCO3)

Nanoparticles

Four-ball tester

Four-ball tester

Four-ball tester

Four-ball tester

Pin-on-Disc

Experimental Setup Four-ball tester

Tribological performance of bio-based lubricant significantly improved at each concentration of CaCO3 nanoparticles, but optimum concentration found at 8 wt% of CaCO3 nanoparticles. 1. Graphite nanoparticles remarkably increased the performance of LB2000 vegetable oil in terms of reduction in friction and wear. 2. Surface found smooth using nanoparticles than pure LB2000 vegetable oil. The coefficient of friction of chemical modified rapeseed oil was found to be less with CuO than WS2 and TiO2 nanoparticles and synthetic lubricant CuO nanoparticles improved the tribological performance of vegetable oils at higher temperatures. Also, the performance of coconut oil found better than mustard oil. Tribological performance of palm oil slightly improved with TiO2 nanoparticles. 1. Friction reduction properties of chemically modified rapeseed oil were improved with the addition of CuO and CeO2 nanoparticles. 2. Anti-wear properties of chemically modified rapeseed oil were not impressive with CuO and CeO2 nanoparticles than synthetic oil.

Major Findings

Azman et al.

2016

2016

2016

2017

2017

[47]

[48]

[49]

[50]

Garg et al.

Kiu et al.

Basker et al.

Gupta and Harsha

Authors

Year

Ref. No. [46]

Karanja oil

-

Chemically modified rapeseed oil

TMP ester (5 vol%) produced from palm oil and polyalphaolefin (95 vol%) Castor oil

Base Fluids

Cu

Graphene sheets (GN), carbon nanotubes (CNT) and graphene oxide (GO)

TiO2, WS2 and CuO

Calcium-copper-titanate nanoparticles (CCTO) and ZDDP

Graphene nanoplatelets

Nanoparticles

Four-ball tester

Four-ball tester

Pin-on-Disc

Four-ball tester

Experimental Setup Four-ball tester

Table 5. (Continued)

Calcium-copper-titanate nanoparticles (CCTO) and ZDDP at 0.25 and 1.0 w/v%, respectively improved the extreme pressure and extreme wear properties of castor oil. The coefficient of friction and specific wear rate was found minimum for bronze material lubricated with CuO nano-based biolubricant. GN with 50 ppm exhibited low wear scar diameter and coefficient of friction among other oil samples including base oil, but further addition of GN impaired the friction and wear. Cu nanoparticles and ZDDP additives improved the tribological characteristics of base oil. Wear was reduced by 30% at 0.5 wt.% concentration of ZDDP additives.

Graphene nanoplatelets improved the tribological properties of TMP ester (5 vol%) PAO (95 vol%) than that of blank lubricant at an optimum concentration (0.005 w%).

Major Findings

Gupta et al.

2018

2018

2018

2018

2018

2018

[52]

[53]

[54]

[55]

[56]

Talib and Rahim

Shafi et al.

Gupta and Harsha

Gupta and Harsha

Gupta and Harsha

Authors

Year

Ref. No. [51]

Modified jatropha oil

Avocado oil

Castor oil

Epoxidized sunflower oil

Castor oil

Epoxidized rapeseed oil

Base Fluids

Hexagonal boron nitride (hBN)

CeO2 and polytetrafluoroethylene (PTFE) Cu

CuO and CeO2

Surface modified CuO

CuO, CeO2 and polytetrafluroethylen (PTFE)

Nanoparticles

NC lath machine

Pin-on-disc

Four-ball tester

Four-ball tester

Four-ball tester

Experimental Setup Four-ball tester 1. CuO nanoparticles impaired the anti-wear property of modified and unmodified rapeseed oil. 2. CeO2 and PTFE nanoparticles significantly improved the anti-wear property for unmodified rapeseed oil at 0.1% w/v concentration. Wear scar diameters were reduced by 28.3 and 22.2% while the coefficient of frictions were decreased by 34.6 and 17.3 % at optimum concentrations of surface-modified CuO nanoparticles in castor oil and paraffin oil. 1. CeO2 nanoparticles showed good compatibility with modified and unmodified sunflower oil and reduced the wear scar diameter. 2. In contrast, CuO impaired the anti-wear property of both bio-based oils. Wear scar diameters were decreased by 37.4 and 35.3% at optimum concentrations of CeO2 and PTFE nanoparticles, respectively. The coefficient of friction was found minimum at 1 wt.% of Cu nanoparticles and minimum wear was found at 0.5 wt.% . Modified jatropha oil with the concentration of 0.05 wt.% of hBN exhibited excellent tribological properties and found correlated with a good machining performance such as small cutting force, small cutting temperature and small surface roughness with long life and less tool wear.

Major Findings

Bhaumik et al.

2018

2019

2019

2020

2020

2020

[58]

[59]

[60]

[61]

[62]

Kumar et al.

Singh et al.

Suresha et al.

Cortes and Ortega

Kerni et al.

Authors

Year

Ref. No. [57]

Canola oil

Chemically treated moringa oleifera

Neem oil

Coconut oil

Chemically treated olive oil

Castor oil

Base Fluids

Copper oxide (CuO)

Silicon carbide (SiC)

Copper (Cu) and hexagonal-boron nitride (h-BN) nanoparticles Copper oxide (CuO) and silicon oxide (SiO2) Graphene nanoplatelets (GNPs)

Zinc oxide (ZnO)

Nanoparticles

Pin-on-disc tribo tester

Pin-on-disc tribo tester

Four ball tester

Customized tribometer

Pin-on-disc tribo tester

Experimental Setup Four-ball tribotester

Table 5. (Continued)

Optimal concentrations of 0.5 % and 1.25% were observed for CuO and SiO2 within coconut oil, respectively. The addition of GNPs within the neem oil was found suitable with the aim to reduce the friction coefficient and wear scar. Modified oil with SiC successfully improved the lubrication performance in comparison to base modified oil and virgin oil (un-treated oil). Canola oil with CuO formed a protective layer that helped to reduce friction and mass loss of metal surface.

ZnO nanoparticles enhanced the tribological performance of castor oil up to 0.1 wt.% concentration of zinc oxide further increasing in zinc oxide concentrations; the deteriorations of contact surfaces were started. Modified oil containing 0.5wt. % of Cu/h-BN was optimum concentration for reducing friction and wear characteristics.

Major Findings

Lubrication Performance of Vegetable Oil-Based Nanofluids …

29

Experimental results revealed that rapeseed oil acted as a friction modifier even at elevated temperatures. Nikolakopoulos and Bompos [67] studied the tribo-performance of journal bearing using mineral oil (SAE30), a synthetic oil (SAE-10W40), and a biodegradable oil (AWS-30) under different speeds and loads. Results showed that biodegradable oil helped in decreasing the friction coefficient in comparison to synthetic oil. Basker et al. [68] investigated the frictional behaviour of chemically modified rapeseed oil with added different nanomaterials (TiO2, WS2, and CuO) and synthetic lubricant (SAE 20W40) using journal bearing test rig. They observed that the oil containing CuO nanomaterial significantly reduced the friction coefficient as compared to other nanolubricants and synthetic lubricants. Lately, Katpatal et al. [69] developed biodegradable lubricants and biodegradable nanolubricants by combining the different quantity of jatropha oil to ISO VG46 oil and adding various weight fractions of CuO nanoparticles to prepared biodegradable lubricant, respectively. They concluded that the fluid film pressure was not increased significantly by using biodegradable nanolubricants as compared to ISO VG46 oil. Further, they suggested biodegradable lubricant to journal bearing as the results of this lubricant found similar to ISO VG46 oil.

CHALLENGES OF VEGETABLE OIL-BASED NANOFLUIDS IN LUBRICATION The above discussed literature indicates that vegetable oil-based nanofluids have significant tribological properties. However, there are some challenges need to be solved. The main challenge is the dispersion and stability of nanoparticles in the base lubricating oil. Nanoparticles have a high surface area, high chemical activity, wide diffusivity, and high adsorption, and are essential to form tribo-film or enhance the surface quality of the contacting surfaces. However, these properties affect the dispersion stability of nanofluids to a great extent. Due to the high surface energy of nanoparticles, they get

30

Anil Dhanola and H. C. Garg

sticked and form large clusters. These large clusters can stimulate the process of abrasive wear. In general, the use of surfactants or surface modification of nanoparticles and proper nanolubricants formulation technology can be used to mitigate this issue. However, the selection of appropriate surfactant and its concentration, and preparation technology are still major concerns for the use of nano-lubricants in lubrication. Some efforts for improving the stability of vegetable oil-based nanofluids by the researchers have been discussed in the upcoming section. Another challenge in vegetable oils is their poor thermo-oxidation stability and low-temperature properties, which further limits the use of biodegradable lubricants as alternative lubricants. Oxidation stability of vegetable oils can be enhanced by changing the structure of the triglycerides chemically or by minimizing the number of unwanted unsaturated fatty acids chains or by using appropriate anti-oxidants. Also, the low-temperature properties can be enhanced by using pour point depressants.

DISPERSION STABILITY AND OTHER THERMO-PHYSICAL PROPERTIES OF VEGETABLE OIL-BASED NANOFLUIDS There is no significance if the colloidal stability of prepared nanofluids/nanolubricants is poor. Poor dispersion stability of nanofluids affects not only the thermal and physical properties but also lubrication performance. High dispersion stability of nanofluids indicates that the aggregation of nanoparticles within the base lubricants is not taken place at a significant rate. Various techniques have been suggested to improve the dispersion stability of nanofluids in which most common methods are the chemical modification of nanoparticles and the use of surfactants. Till now, very few researchers have taken interest in the dispersion stability of vegetable oil-based nanofluids, as tabulated in Table 6.

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31

Table 6. Summary of dispersion stability of vegetable oil-based nanolubricants Vegetable oil/nanoparticles

Surfactant used

Chemically modified palm oil/MoS2 and CuO Castor oil/CuO

Oleic acid

Avocado oil/Cu

-

Chemically processed moringa oleifera oil/SiC Canola oil/CuO

Triton X-100

Canola oil/TiO2

Triton X-100

SDS

SDS

Stability measurement method UV-Vis spectroscopy Visual inspection Visual inspection UV-Vis spectroscopy Visual inspection Zeta potential

Key findings

Reference

High stability observed thus, tribological properties improved. No significant changes were observed until 48 hours. Stability was maintained even after the passing of 10 days. No significant changes were noted until 120 hours.

[38]

Observed higher stability

[62]

Very less sedimentation of nanoparticles was observed until 30 days of preparation

[70]

[52] [55] [61]

The lubrication performance of lubricating oil is also decided by its thermal and physical properties, such as thermal conductivity and rheological behaviour. Oil having higher thermal conductivity indicates that oil can carry away the heat at a better rate. In general, the thermal conductivity of nanofluids is operated by the Brownian motion of nanoparticles. In rheology science, the viscosity of a fluid with the variation of shear rate, shear stress, and the temperature is studied. It has been observed that the blending of nanoparticles in base fluid enhances the base fluid viscosity. Oil-based nanofluids having good viscosity are considered good to work under hydrodynamic lubrication regime. Recent progress on the thermal and physical properties of vegetable oil-based nanofluids is presented in Table 7.

Chemically processed moringa oleifera oil Canola oil

Soybean, sunflower, corn and paraffinic and corn oils 0.1% and 1.0%

0.01 vol. %0.04 vol.%

SiC

TiO2

0.05 wt. %0.25 wt. %

0.1 %

Al2O3, CuO Iron oxide (Fe3O3) SiO2 nanoparticles

Combination of VG46 oil and jatropha oil Rice bran oil

0.35 wt. %1.05 wt. % 0.5 wt. %3 wt.%

Silicon carbide (SiC) Surface modified CuO

Coconut oil

Concentration 0.5-4%

Nanoparticles Carbon nanotube (CNT)

Vegetable oil Palm oil

At all the temperatures, rice bran oil containing CuO nanoparticle showed higher viscosity and thermal conductivity than the other two oils. All the prepared nanofluids showed good thermal conductivity at elevated temperatures. The highest enhancement in thermal conductivity (11%) was observed for corn oil and soybean oil at 313 K and 0.25 wt. % in concentration. Maximum enhancement in viscosity was observed higher for 1.0% concentration, and the viscosity of nanolubricants decreased with the increase of temperature. All nanolubricants including base oil showed Newtonian behaviour under a certain range of shear rate (i.e., 1-1000 s-1)

Observations Thermal conductivity and viscosity of nanofluids increased with the increase of particle loading. At the concentration range, poor thermal conductivity was observed due to particle agglomeration. Thermal conductivity and viscosity remarkably enhanced by incorporating SiC nanoparticles. The higher proportion of VG46 oil in jatropha oil with 1.5 wt. % CuO showed higher viscosity than the rest of the samples.

[76]

[61]

[75]

[74]

[73]

[72]

Reference [71]

Table 7. Summary of Influence of nanoparticles on thermal conductivity and viscosity of vegetable oil

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CONCLUSION This chapter presents the recent advancements in the field of vegetable oil-based nanofluids. For the past few years, plenty of works have been carried out on environmentally acceptable lubricants due to biodegradability issue with petroleum-based lubricants. The presented investigations in the chapter reveal that the blending of nanoparticles into vegetable oils improves the lubrication performance; thus, the vegetable oils can be potential candidates to replace the conventional lubricants. Despite the fact that the vegetable oils have the potential to work in boundary and hydrodynamic lubrication, there have been limited works devoted to hydrodynamic lubrication regime in comparison to boundary lubrication regime. Therefore, more attention should be paid in this direction. There are some other challenges associated with vegetable oilbased nanofluids poor oxidation stability and maintain the stability of nanoparticles in the vegetable oils for a long duration. The addition of appropriate anti-oxidants and chemical modification via transesterification and epoxidation are the common methods to improve the oxidation stability. Whereas, the dispersion stability of nanofluids can be improved by the addition of surfactants and chemical modification of nanoparticles. As the lubrication performance of vegetable oil-based nanofluids is governed by their thermal and physical properties and dispersion stability, it has been noticed that very few researchers have taken interests in these factors. Therefore more studies should be investigated on these parameters to open up the scope of vegetable oil-based nanofluids as industrial lubricants. Lastly, the tribological mechanism of nanoparticles is still complicated to understand as many types of nanoparticles are available. Therefore, more studies should be addressed to understand the lubrication mechanisms of nanofluids in detail by employing analytical and molecular simulation techniques.

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[32] Gu, K., Chen, B., Wang, X., Wang, J., Fang, J., Wu, J., and Yang, X. 2014. “Preparation, Friction, and Wear Behaviors of Cerium-Doped Anatase Nanophases in Rapeseed Oil.” Industrial and Engineering Chemistry Research 53:6249–54. [33] Arumugam, S., and Sriram, G. 2014. “Synthesis and Characterization of Rapeseed Oil Bio-Lubricant Dispersed with Nano Copper Oxide: It’s Effect on Wear and Frictional Behavior of Piston Ring–Cylinder Liner Combination.” Proceedings of the institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 228:1308–18. [34] Mahipal, D., Krishnanunni, P., Mohammed Rafeekh, P., and Jayadas, N. H. 2014. Analysis of Lubrication Properties of Zinc-DialkylDithio-Phosphate (ZDDP) Additive on Karanja Oil (Pongamia Pinnatta) As a Green Lubricant. International Journal of Engineering Research 3:494–6. [35] Gu, K., Chen, B., and Chen, Y. 2013. “Preparation and tribological properties of lanthanum-doped TiO2 nanoparticles in rapeseed oil.” Journal of Rare Earths 31:89–94. [36] Zhao, C., Jiao, Y., Chen, Y. K, and Ren, G. 2014. “The Tribological Properties of Zinc Borate Ultrafine Powder as a Lubricant Additive in Sunflower Oil.” Tribology Transactions 57: 425–34. [37] Koshy, C. P., Rajendrakumar, P. K., and Thottackkad, M. V. 2015. “Evaluation of the Tribological and Thermo-Physical Properties of Coconut Oil Added with MoS2 Nanoparticles at Elevated Temperatures.” Wear 330-331:288–308. [38] Gulzar, M., Masjuki, H., Varman, M., Kalam, M., Mufti, R. A., Zulkifli, N., Yunus, R., and Zahid, R. 2015. “Improving the AW/EP Ability of Chemically Modified Palm Oil by Adding CuO and MoS2 Nanoparticles.” Tribology International 88:271–9. [39] Gulzar, M., Masjuki, H. H., Kalam, M. A., Varman, M., Mufti, R. A., Zahid, R., and Yunus, R. 2015. “AW/EP Behavior of WS2 Nanoparticles Added to Vegetable Oil-Based Lubricant.” Paper presented at Malaysian International Tribology Conference, Malaysia.

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[40] Zainal, N. A., Zulkifli, M., Wahidah, N., Mahshuri, Y., Hassan, M. and Yunus, R. 2015. “The feasibility study of CaCO3 derived from cockleshell as nanoparticle in chemically modified lubricant.” Paper presented at Malaysian International Tribology Conference, Penang, Malaysia, November 16-17. [41] Su, Y., Gong, L., and Chen, D. 2015. An Investigation on Tribological Properties and Lubrication Mechanism of Graphite Nanoparticles as Vegetable Based Oil Additive. Journal of Nano materials 2015:1–7. [42] Baskar, S., Sriram, G., and Arumugam, S. 2015. “Experimental Analysis on Tribological Behavior of Nano Based Bio-Lubricants Using Four Ball Tribometer.” Tribology in Industry 37:449–54. [43] Koshy, C. P., Rajendrakumar, P. K., and Thottackkad, M. V. 2015. “Analysis of Tribological and Thermo-Physical Properties of Surfactant-Modified Vegetable Oil-Based CuO Nano-Lubricants at Elevated Temperatures - An Experimental Study.” Tribology Online 10:344–53. [44] Shaari, M. Z., Nik Roselina, N. R., Kasolang, S., Hyie, K. M., Murad, M. C., and Bakar M. A. A. 2015. “Investigation of Tribological Properties of Palm Oil Biolubricant Modified Nanoparticles.” Journal Technology (Sciences & Engineering) 76:69–73. [45] Kashyap, A., and Harsha, A. 2016. “Tribological Studies on Chemically Modified Rapeseed Oil with CuO and CeO2 Nanoparticles.” Proceedings of the institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 230:1562–71. [46] Azman, S. S. N., Zulkifli, N. W. M., Masjuki, H., Gulzar, M., and Zahid, R. 2016. “Study of Tribological Properties of Lubricating Oil Blend Added with Graphene Nanoplatelets.” Journal of Material Research 31:1932–8. [47] Gupta, R. N., and Harsha, A. P. 2016. “Synthesis Characterization and Tribological Studies of Calcium–Copper–Titanate Nanoparticles as a Biolubricant Additive.” Journal of Tribology 139: 021801.

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[48] Baskar, S., Sriram, G., and Arumugam, S. 2016. “The Use of Doptimal Design for Modeling and Analyzing the Tribological Characteristics of Journal Bearing Materials Lubricated by NanoBased Biolubricants.” Tribology Transactions 59:44–54. [49] Kiu, S. S. K., Yusup, S., Chok, V. S., Taufiq, A., Kamil, R. N. M., Syahrullail, S., and Chin B. L. F. Comparison on Tribological Properties of Vegetable Oil upon Addition of Carbon Based Nanoparticles.” IOP Conference Series: Material Science and Engineering 206; 012043. [50] Garg, P., Kumar, A., Thakre, G. D., Arya, P. K., and Jain, A. K. 2017. “Investigating Efficacy of Cu Nano-Particles as Additive for Bio-Lubricants. Macromolecular Symposia 346; 1700010. [51] Gupta, R. N., Harsha, A. P., and Singh, S. 2018. “Tribological Study on Rapeseed Oil with Nano-Additives in Close Contact Sliding Situation.” Applied Nanoscience 8:567–80. [52] Gupta, R. N. & Harsha, A. P. 2018. “Tribological study of castor oil with surface-modified CuO nanoparticles in boundary lubrication.” Industrial Lubrication and Tribology 70-700–10. [53] Gupta, R. N., and Harsha, A. P. 2018. “Friction and Wear of Nanoadditive-Based Biolubricants in Steel–Steel Sliding Contacts: A Comparative Study.” Journal of Material Engineering Performance 27:648–58. [54] Gupta, R. N., and Harsha, A. 2018. “Antiwear and Extreme Pressure Performance of Castor Oil with Nano-Additives.” Proceedings of the institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232:1055–67. [55] Shafi, W. K., Raina, A., and Ul Haq M. I. 2018. “Tribological Performance of Avocado Oil Containing Copper Nanoparticles in Mixed and Boundary Lubrication Regime.” Industrial Lubrication and Tribology 70:865–71. [56] Talib, N., and Rahim, E. A. 2018. “Performance of Modified Jatropha Oil in Combination with Hexagonal Boron Nitride Particles as a Bio-Based Lubricant for Green Machining.” Tribology International 118:89–104.

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[57] Bhaumik, S., Maggirwar, R., Datta, S., and Pathak, S. D. 2018. “Analyses of Anti-Wear and Extreme Pressure Properties of Castor Oil with Zinc Oxide Nano Friction Modifiers. Applied Surface Science 449:277–86. [58] Kerni, L., Raina, A., and Haq, M. I. U. 2019. “Friction and Wear Performance of Olive Oil Containing Nanoparticles in Boundary and Mixed Lubrication Regimes. Wear 426–427:819–27. [59] Cortes, V., and Ortega, J. A. 2019. “Evaluating the Rheological and Tribological Behaviors of Coconut Oil Modified with Nanoparticles as Lubricant Additives.” Lubricants 7; 76. [60] Suresha, B., Hemanth, G., Rakesh, A., and Adarsh, K. M. 2020. “Tribological Behaviour of Neem Oil with and without Graphene Nanoplatelets Using Four-Ball Tester.” Advances in Tribology. https://doi.org/10.1155/2020/1984931. [61] Singh, Y., Sharma, A., Singh, N. K., and Noor, M. M. 2020. “Effect of SiC Nanoparticles Concentration on Novel Feedstock Moringa Oleifera Chemically Treated with Neopentylglycol and their Tribological Behavior.” Fuel. https://doi.org/10.1016/j.fuel.2020. 118630. [62] Kumar, V., Dhanola, A., Garg, H. C., and Kumar, G. 2020. “Improving the Tribological Performance of Canola Oil by Adding CuO Nanoadditives for Steel/Steel Contact.” Materials Today: Proceedings 28:1392-1396. [63] Quinchia, L. A., Delgado, M. A., Reddyhoff, T., Gallegos, C., and Spikes, H. A. 2014. “Tribological Studies of Potential Vegetable OilBased Lubricants Containing Environmentally Friendly Viscosity Modifiers.” Tribology International 69:110–7. [64] Adhvaryu, A., Erhan, S. Z., and Perez, J. M. 2004. “Tribological Studies of Thermally and Chemically Modified Vegetable Oils for Use as Environmentally Friendly Lubricants.” Wear 257:359–67. [65] Durak, E., Cetinkaya, M., Yenigun, B., and Karaosmanoglu. 2004. “Effects of Sunflower Oil Added to Base Oil on the Friction Coefficient of Statically Loaded Journal Bearing.” Journal of Synthetic Lubrication 21:207-22.

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[66] Durak, E. 2004. “A Study on Friction Behavior of Rapeseed Oil as an Environmentally Friendly Additive in Lubricating Oil.” Industrial Lubrication and Tribology 56:23-37. [67] Nikolakopoulos, P. G., and Bompos, D. A. 2015. “Experimental Measurements of Journal Bearing Friction Using Mineral, Synthetic, and Bio-Based Lubricants. Lubricants 2015:155–63. [68] Baskar, S., Sriram, G., and Arumugam, S. 2016. “Tribological Analysis of a Hydrodynamic Journal Bearing Under the Influence of Synthetic and Biolubricants.” Tribology Transactions 60:428-436. [69] Katpatal, D. C., Andhare, A. B., and Padole, P. M. 2019. Performance of Nano-Bio-Lubricants, ISO VG46 Oil and its Blend with Jatropha Oil in Statically Loaded Hydrodynamic Plain Journal Bearing. Proceedings of the institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234:386-400. [70] Dhanola, A., and Garg, H. C. 2020. “Experimental Analysis on Stability and Rheological Behaviour of TiO2/Canola Oil Nanolubricants.” Materials Today: Proceedings 28:1285-1289. [71] Li, B., Li, C., Zhang, Y., Wang, Y., Yang, M., Jia, D., Zhang, N., and Wu, Q. 2017. “Effect of the Physical Properties of Different Vegetable Oil-Based Nanofluids on MQLC Grinding Temperature of Ni-Based Alloy. The International Journal of Advanced Manufacturing Technology 89:3459-3474. [72] Sadiq, I. O., Sharif, S., Suhaimi, M. A., Yusof, N. M., Kim, D. W., and Park, K. H. 2018. “Enhancement of Thermo-Physical and Lubricating Properties of SiC Nanolubricants for Machining Operation.” Procedia Manufacturing, 17, pp. 166-173. [73] Katpatal, D. C., Andhare, A. B., and Padole, P. M. 2019. “Viscosity Behaviour and Thermal Conductivity Prediction of CuO-Blend Oil Based Nano-Blended Lubricant.” Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233:1154-1168. [74] Das, A., Patel, S. K. and Das, S. R. 2019. “Performance Comparison of Vegetable Oil Based Nanofluids towards Machinability

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Improvement in Hard Turning of HSLA Steel Using Minimum Quantity Lubrication.” Mechanics & Industry 20; 506. [75] Taha-Tijerina, J., Aviña, K., and Diabb, J. M. 2019. “Tribological and Thermal Transport Performance of SiO2-Based Natural Lubricants.” Lubricants 7; 71. [76] Dhanola, A. and Garg, H. C. 2020. “Influence of Different Surfactants on the Stability and Varying Concentrations of TiO2 Nanoparticles on the Rheological Properties of Canola Oil-Based Nanolubricants.” Applied Nanoscience. https://doi.org/10.1007/ s13204-020-01467-y.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 2

PUTRANJIVA ROXBURGHII: A NOVEL FEEDSTOCK AS A BIO-BASED LUBRICANT WITH MOS2 NANOPARTICLES EFFECT AND TRIBOLOGICAL ANALYSIS Yashvir Singh1,* and Nishant Kumar Singh2 1

Department of Mechanical Engineering, Graphic Era Deemed To Be University, Dehradun, Uttarakhand, India 2 Department of Mechanical Engineering, Hindustan College of Science and Technology, Mathura, UP India

ABSTRACT In this study, the tribological characterization of the Putranjiva oil was analyzed with the effect of MoS2 nanoparticles. The test was performed on a pin on disc tribometer by considering different conditions. Based on the specific concentration (percent) of nanoparticles, nano lubricants were properly dispersed through the ultrasonication process. In light of the investigation, a 0.5% concentration of MoS 2 nanoparticles demonstrated a decrease in coefficient of friction and wear rate. The SEM images also show better surfaces when the nanoparticle

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Yashvir Singh and Nishant Kumar Singh was added up to 0.5% concentration which was due to the adhesion effect. The optimum addition was found at 0.5% concentration to the base oil.

Keywords: concentration, putranjiva oil, wear, silica nanoparticles, friction

INTRODUCTION The use of mineral oil is enormous among oil-based commodities due to its application for lubrication reasons [1]. There are some environmental problems associated with the use of hydrocarbon oil since they are accountable for marine pollution owing to spillage after use [2]. There is a need to find an alternative that may be used to replace synthetic oil. Because of this point, the author concentrated on the discovery of a replacement for synthetic oil. Biolubricant is one of the assets and plays a key role in the improvement of sustainability, which is progressively economic and innocuous to nature where it is used. Farfan-Cabrera et al. [3] assessed the effect of thermal aging on the lubricity of the jatropha oil during its usage in engines. There was no effect on the frictional behavior observed by thermal aging but the wear was reduced by its effect. Biolubricant has better biodegradability compared to oil-based synthetic oils, but certain limitations are there which need to be addressed for proper tribological applications [4]. Physicochemical characteristics were important for the use of substitute oils such as viscosity, flash point, and fire point in addition to enhancing the physicochemical attributes, nanoparticles are one of the appropriately added substances; numerous tests have been conducted to identify the impact of nanoparticles on tribological attributes, while the previous studies were based on their application to the conventional petroleum lubricants [5-7]. Xie et al. [8] evaluated the effect of silicon dioxide and molybdenum disulfide nanoparticles on engine oil tribology. Better results were obtained in terms of reducing friction and provide improved lubrication. Wang et al. [9]

Putranjiva Roxburghii

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evaluated the effect of hBN nanoparticles on the castor oil. The 5% blend of the castor oil was found effective in improved tribological behavior. In the previous studies, the application of Putranjiva oil with the effect of Molybdenum Disulphide (MoS2) nanoparticles have never been considered for tribological applications. Most of the studies were performed by using it as biodiesel. Putranjiva tree belongs to the family Euphorbiacae. They are abundantly available in tropical regions and their seeds contain around 44.5% oil [10]. Based on the literature available, the author has decided to conduct a tribological analysis for its possible application in this field. In the present investigation, raw Putranjiva oil has been considered as the reference oil, and further MoS2 nanoparticles are added to the base oil to check its lubrication characteristics.

MATERIALS AND METHODS Composition of P. Roxburghii For the evaluation purpose, raw Putranjiva oil was procured from the M/s Pallishree Limited, Kolkata. The oil mainly contains triglyceride esters of fatty acids and glycerol which were estimated according to European standard method EN14103:2003. Gas Chromatography was used to identify the fatty acids present in the Putranjiva oil. The Gas chromatography equipment consists of a capillary column with 30 mm and 0.25 mm length and diameter respectively. Samples were injected with a flow rate ratio of 24:1. The Helium was used as the carrier gas maintaining a flow rate of 2 ml/min. The temperature during the injection process was maintained at 250oC. The program was set in the set up with start at 120oC and holding for 5 minutes. The heating was set at 2oC per minute. The most dominant factor in the raw Putranjiva oil is the presence of oleic acid contributing to around 48.12%. Around 28.32% amount of linoleic acid is also present in the raw oil. Figure 1 shows the amount of fatty acids present in Putranjiva oil [11].

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Yashvir Singh and Nishant Kumar Singh

Figure 1. Fatty acid composition of the Putranjiva oil.

Nano Lubricant Development and Their Characterization To prepare the nano lubricants for the analysis, Putranjiva oil was taken in a flask. The nanoparticles were procured from the M/s Intelligent Materials Private Ltd, Punjab. The purity was 99.9% as per the record provided by the supplier. The diameter of the nanoparticles ranges between 30 nm to 50 nm having a spherical shape. The nanoparticles were added to the oil on the weightage basis (0.1%, 0.5%, and 0.9%). To proper blending of the nanoparticles into the oil, the ultrasonication process was performed. The probe sonicator was run for 2 h at 45oC temperature. To examine the proper dispersion of the nanoparticles, ultraviolet light was passed through the samples and there was no separation was observed. The kinematic viscosity was evaluated through the viscometer (M/s Swastik systems and services, New Delhi) based on the ASTM D-445 standard. Flash point and pour point of the oil was measured according to ASTM D-92 (Cleveland open cup method) and ASTM D-97 respectively, using proper apparatus. Table 1 shows the properties of the samples considered for the test.

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Table 1. Properties of the Putranjiva oil with nanoparticles concentration Materials properties Properties Kinematic viscosity (mm2/s) at 40oC Kinematic viscosity (mm2/s) at 100oC Density (kg/m3) at 15oC Flash point (oC) Pour point (oC) Iodine value Acid value (mg KOH/g)

Putranjiva oil 59.16

PO+0.1% 59.73

PO+0.5% 61.14

PO+0.9% 64.14

11.15

11.52

12.42

14.14

927.23 149 -3.08 83.12 8.36

927.89 150.21 -3.17 83.12 8.39

929.18 152.31 -4.05 83.42 8.71

932.29 154.12 -4.92 84.02 9.08

Materials During this study, LM 13 alloy was procured from the M/s Bharat Aerospace Metals, Mumbai which was used as pin material for the test. The purpose of consideration of this material due to its application for the piston which faces maximum friction and the hardness is 98 HRB. This type of alloy was also capable to resist wear and corrosion. For the Disc, EN 31 steel was used as it contains more amount of hardness (62 HRC) and it is highly worn resistive. The pin was cylindrically shaped by employing a turning operation on the lathe machine. The one end of the pin was made spherical to get the point effect while mating with the disc. The pin consists of 10 mm diameter and length was 30 mm. The pin was further polished by using emery paper of following grit sizes 200, 400 600, and 1200 nm before experimenting on the machine.

Experimental Setup The pin on disc machine was purchased from the M/s DUCOM, Bangalore, India that was used for investigating the friction and wear

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characteristics during the application of lubricants. Figure 2 shows the image of the mechanism involving point contact of pin and disc. The friction force was obtained on the screen with the help of the load cell attached to the analysis machine. For obtaining the friction coefficient, friction force was normalized by the load applied. The lubricant was provided in a dropwise way to the interfaces with the help of the pump operated by the electric motor. The SEM images were used to study the worn-out surface during the analysis. Table 2 mentioned the conditions considered for the examination of the samples.

Figure 2. Schematic image of the mechanism involved in the DUCOM machine.

Table 2. Condition took during the analysis Conditions considered Applied load (kgf) Sliding speed (rpm) Temperature (oC) Duration (s)

Value 10 ± 2 150 ± 30 70 ± 3 3600

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RESULTS AND DISCUSSION Frictional Analysis Figure 3 shows the friction behavior of the nano lubricants. The minimum coefficient of friction was obtained when a concentration of 0.5% nanoparticles is there in the oil. The coefficient of friction was reduced by about 8.23% when compared to the raw oil. The mechanism of friction reduction involves the filling of gaps on the surfaces with nanoparticles which provides smoother and better lubricity. With the addition of the nanoparticles, contact surface area increased which resulted in a reduction of the applied pressure and a rolling mechanism occurs instead of sliding friction. The same reason has also been reported by Ghaednia et al. [12]. Based on the above results, it can be inferred that an optimum concentration of the nanoparticles is desired to receive better contact with the surface mechanism. When the concentration becomes lower e.g., 0.02% and 0.03% etc., there is a limited conversion of the sliding motion into a rolling one which attributed more friction. After a certain limit of nanoparticle concentration, particles get aggregated on the metals which enhance friction and wear on the surface during their contact. The same hypothesis has also been reported in the previous studies and also presenting abrasive wear with increased nanoparticle concentration [13-15].

Wear Rate The concentration of MoS2 nanoparticles up to 0.5% also showed a minimum wear rate of the pin when compared to the raw Putranjiva oil as shown in Fig 4. The reduction in the wear was around 11.2%. The nanoparticle's effect on the anti-wear property depends on the proper dispersion of the particles in the lubricant. The MoS2 nanoparticles are having the capability to get properly dispersed in the solution which

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promotes an anti-wear mechanism. These results are also justified by the SEM images of the samples considered for the analysis.

Figure 3. Coefficient of friction of Putranjiva oil with nanoparticle concentration.

Figure 4. Wear rate of different samples.

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Surface Morphology Figure 5 shows the SEM images of the lubricant samples obtained after performing the test. Figure 5 (a) shows the SEM images for the base oil. The delamination of the surface has been observed and the occurrence of the ploughing effect results in the formation of the parallel grooves. The addition of the nanoparticles up to 0.5% results in a less wear volume as they provide a defensive film between the surfaces during their motion. Figure 5 (b) shows the SEM images with the effect of 0.5% molybdenum disulfide nanoparticles addition. The minimum damage to the surface was observed which was due to the abrasion. There is the fewer amount of grooves that characterized the abrasion effect. However, a further increase in nanoparticles results in more amount of wear volume. Figure 5 (c) shows the effect of adhesion and abrasion on the surface when the amount of silicon oxide nanoparticles further increased. The formation of the fine grooves is due to the ploughing effect occurred on the surface [16].

Figure 5. SEM images of the lubricants tested (a) Raw Putranjiva oil (b) PO+0.5% (c) PO + 0.9%.

CONCLUSION Based on the observations, an improvement in the tribological characteristics of the Putranjiva oil is achieved by considering the Molybdenum Disulphide nanoparticles. The following conclusions are drawn from this work:

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



The addition of the MoS2 nanoparticles to the chemically modified oil improves the lubricity of the samples. With the addition of up to 0.5% concentration, better results are obtained in terms of reducing friction. Their addition to the lubricant assists in forming a better defensive film between the surfaces and prevents direct contact of metals during the motion. The raw oil shows maximum damage to the surface with comparison to other lubricants. This was due to the delamination of the surface. The addition of the nanoparticles up to 0.5% to the modified oil shows less wear and damage to the surface. This was due to the proper dispersion of the MoS2 nanoparticles on the surface due to localized heating and melting of the particles. Based on the results obtained, the introduction of nanoparticles to a threshold of 0.5% has the potential to improve the tribological efficiency of the oil. The use of this type of bio-based lubricant, which is environmentally friendly, could also help to save energy.

REFERENCES [1]

[2]

[3]

Ali, M. K. A., H. Xianjun, L. Mai, C. Bicheng, R. F. Turkson, and C. Qingping, “Reducing frictional power losses and improving the scuffing resistance in automotive engines using hybrid nanomaterials as nano-lubricant additives,” Wear, vol. 364-365, pp. 270-281, 2016/10/15/2016. Zheng, G., T. Ding, Y. Huang, L. Zheng, and T. Ren, “Fatty acid based phosphite ionic liquids as multifunctional lubricant additives in mineral oil and refined vegetable oil,” Tribology International, vol. 123, pp. 316-324, 2018/07/01/2018. Farfan-Cabrera, L. I., E. A. Gallardo-Hernández, M. GómezGuarneros, J. Pérez-González, and J. G. Godínez-Salcedo, “Alteration of lubricity of Jatropha oil used as bio-lubricant for engines due to thermal ageing,” Renewable Energy, vol. 149, pp. 1197-1204, 2020/04/01/2020.

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Ansari, M. I., and D. G. Thakur, “Influence of surfactant: Using electroless ternary nanocomposite coatings to enhance the surface properties on AZ91 magnesium alloy,” Surfaces and Interfaces, vol. 7, pp. 20-28, 2017/06/01/2017. [5] Araújo Junior, A. S., W. F. Sales, R. B. da Silva, E. S. Costa, and Á. Rocha Machado, “Lubri-cooling and tribological behavior of vegetable oils during milling of AISI 1045 steel focusing on sustainable manufacturing,” Journal of Cleaner Production, vol. 156, pp. 635-647, 2017/07/10/2017. [6] Bhaumik, S., R. Maggirwar, S. Datta, and S. D. Pathak, “Analyses of anti-wear and extreme pressure properties of castor oil with zinc oxide nano friction modifiers,” Applied Surface Science, vol. 449, pp. 277-286, 2018/08/15/2018. [7] Cavalcanti, E. D. C., É. C. G. Aguieiras, P. R. da Silva, J. G. Duarte, E. P. Cipolatti, R. Fernandez-Lafuente, et al., “Improved production of biolubricants from soybean oil and different polyols via esterification reaction catalyzed by immobilized lipase from Candida rugosa,” Fuel, vol. 215, pp. 705-713, 2018/03/01/2018. [8] Xie, H., B. Jiang, B. Liu, Q. Wang, J. Xu, and F. Pan, “An Investigation on the Tribological Performances of the SiO2/MoS2 Hybrid Nanofluids for Magnesium Alloy-Steel Contacts,” Nanoscale Research Letters, vol. 11, p. 329, 2016/07/15 2016. [9] Wang, Y., Z. Wan, L. Lu, Z. Zhang, and Y. Tang, “Friction and wear mechanisms of castor oil with addition of hexagonal boron nitride nanoparticles,” Tribology International, vol. 124, pp. 10-22, 2018/08/01/2018. [10] Haldar, S. K., B. B. Ghosh, and A. Nag, “Utilization of unattended Putranjiva roxburghii non-edible oil as fuel in diesel engine,” Renewable Energy, vol. 34, pp. 343-347, 2009/01/01/2009. [11] Acharya, N., P. Nanda, S. Panda, and S. Acharya, “A comparative study of stability characteristics of mahua and jatropha biodiesel and their blends,” Journal of King Saud University - Engineering Sciences, 2017/09/20/2017. [4]

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[12] Ghaednia, H., R. L. Jackson, and J. M. Khodadadi, “Experimental analysis of stable CuO nanoparticle enhanced lubricants,” Journal of Experimental Nanoscience, vol. 10, pp. 1-18, 2015/01/02 2015. [13] Ali, M. K. A., H. Xianjun, L. Mai, C. Qingping, R. F. Turkson, and C. Bicheng, “Improving the tribological characteristics of piston ring assembly in automotive engines using Al2O3 and TiO2 nanomaterials as nano-lubricant additives,” Tribology International, vol. 103, pp. 540-554, 2016/11/01/2016. [14] Asnida, M., S. Hisham, N. W. Awang, A. K. Amirruddin, M. M. Noor, K. Kadirgama, et al., “Copper (II) oxide nanoparticles as additve in engine oil to increase the durability of piston-liner contact,” Fuel, vol. 212, pp. 656-667, 2018/01/15/2018. [15] Chen, Y., P. Renner, and H. Liang, “Dispersion of Nanoparticles in Lubricating Oil: A Critical Review,” Lubricants, vol. 7, p. 7, 2019. [16] Awang, N. W., D. Ramasamy, K. Kadirgama, G. Najafi, and N. A. Che Sidik, “Study on friction and wear of Cellulose Nanocrystal (CNC) nanoparticle as lubricating additive in engine oil,” International Journal of Heat and Mass Transfer, vol. 131, pp. 11961204, 2019/03/01/2019.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 3

APPLICATION OF NANOPARTICLES TO VEGETABLE OIL FOR IMPROVED THERMAL MECHANICAL PROPERTIES Anupama Mogha Dr. S. S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh, India

ABSTRACT Increased environmental concerns and declining fossil fuels force one to move on to a more natural and renewable resource source. Vegetable processing in various processes instead of renewable mining oil resources has been initiated. The beauty and effectiveness of vegetable oils make them potential candidates to replace renewable resources. They are non-toxic, cost-effective and environmentally friendly and their products simply reduce the risk of harm to the human and the environment. Vegetable oils find many applications in the field of biomedical, polymer and paint industry and varnishes. With the incorporation of nanoscale particles or nanofiller the utilization and properties of vegetable oils can be improved to achieve higher mechanical and thermal properties.

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Keywords: renewable resource, vegetable oils, mineral oil, nanoscale particles, environment friendly

1. INTRODUCTION Among the renewable resources, the vegetable oils are considered the most significant due to their easy availability, low cost, nontoxic nature and wide range of applications. With the emergence of nanotechnology, their utility in the field of nanocomposites is studied. The composites synthesized provides a range of thermal, physical and mechanical properties from flexible rubbers to rigid plastics, that show potential alternative to petroleum-based products [1]. Vegetable oil for various application is shown in Figure 1. Rising environmental concerns and the depletion of natural resources are forcing researchers to move to renewable natural sources of polyols in vegetable oils. Natural oil polyols (NOPs), also known as biopolyols, are polyols obtained from vegetable oils in various ways. NOPs are generally used for the synthesis of polyurethanes. Different methods were developed to produce NOPs, with different properties but with the same triglyceride fats in the structure. Naturally available polyol from a plant source that can be directly used is also available like castor oil [2-4]. Due to the depletion of fuel resources and environmental concerns, polyols are being made from renewable sources such as vegetable oil, starch, cellulose and lignin [5]. Polyurethanes based on vegetable oils such as castor oil and canola oil have excellent formulations, as well as thermal properties and high resistance [6]. The use of renewable polyols contributes to sustainable development due to their low toxicity and a small reduction of the resulting mixture. Polyurethane from non-renewable materials can replace oligomers based on mineral oil [7]. The major advantages and disadvantages of vegetable oil were listed in Table 1.

Application of Nanoparticles to Vegetable Oil …

Figure 1. Vegetable oils for various applications.

Table 1. Advantages and disadvantages of vegetable oils [8] Advantages Low toxicity High biodegradability High Flash point Wide number of products Low production cost Environmental friendly Additive compatibility

Disadvantages Low thermal stability Poor corrosion protection Oxidative stability High freezing point

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1.1. Castor oil as Renewable Raw Material Renewable PU sources like vegetable oils and castor oil are gaining importance. Castor oil can be used as polyol content as it contains an active group of hydroxyl (−OH) in its structure, thus widely used in many chemical industries, especially in the production of polyurethanes [9]. Due to its low cost, low toxicity, and readily available, castor oil is a promising raw material. Castor oil has many commercial applications due to its composition, which is as large as a hydroxyl group containing ricinoleic acid. Therefore, castor oil is used as a triple polyol without the chemical modification of polyurethane compounds [10-12]. The basic chemical structure of castor oil is shown in Figure 2 and its some major applications are given in Figure 3. The significance of castor oil as a flame retardant in polyurethane foam has been studied by salisu et al. Foams based on castor oil have excellent durability, shock absorption and electrical protection properties. These new varieties of prepared foam are replacing halogen based flame retardants. There is a noticeable increase in foam body structures, with increased content of castor oil. The incubation time increases with a higher amount of castor oil [14].

Figure 2. Chemical structure of Castor oil [13].

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Figure 3. Applications of castor oil [13].

Appropriate physicochemical castor oil based polyurethanes (COPUs) were studied using Multiwall Carbon Nanotubes (MWCNTs). Different percentages of weight (0% to 1% wt) of MWCNTs are applied to nanocomposites based on castor oil. Proper distribution of MWCNTs on a polyurethane matrix with different percentages of weight was observed. The above study revealed the presence of very small pores, made up of 0.3 wt% of MWCNTs, which are in good agreement with the availability of barriers, reduced to 68% in 1 wt% and 70% in 0.5 wt% of MWCNTs inpolymer matrix, in comparison to samples of pure COPUs as read by Ali et al. [15]. In recent years, the use of castor oil based polyurethanes classified as a thermally active shape memory (TASM) has received worldwide attention due to its applications in the field of microelectro-mechanical systems, livelihoods and health monitoring devices [16, 17]. Also, the castor oil based segmented polyurethanes has excellent physical properties and good biocompatibility. Castor oil-based diol were used as raw materials to increase the amount of carbon from renewable resources in bionanocomposites. These highly targeted bio-nanocomposites will be used as smart devices, where thermal structure structures are needed [18, 19].

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Series of thermoplastic polyurethane segmented with castor oil was prepared in this study. The polyurethanes prepared have proved high break elongation, excellent elastic recovery with good mechanical and thermal properties. The hydroxyl functionality of castor oil is 2.7, leading to the formation of a polymer structure in three-dimension [20]. Polyurethanes obtained from polyols derived from renewable castor oil, and isophorone diisocyanate was studied. There is a noticeable effect of type of polyol and fillers on the properties like maximum stress, percent elongation, and contact angle of the composite. Cross-linking leads to chemical modification of the polyols, hence improves the properties of the resulting materials. The mechanical features of the PUs depend largely on the number of hydroxyl groups in the polyol, interactions between the hard and soft segment and hydrogen bonds of the matrix. Higher hydroxyl indexed polyols showed high mechanical and thermal conductivities [21]. Composites of PLA with castor oil-based polyurethane pre-polymer (COPUP) were prepared. The spread of COPUP into the PLA matrix will increase the inherent brittleness of the polymer matrix. The efficiency of the castor oil can be used effectively for the synthesis of NCO terminated polyurethane prepolymers. The brittle mode of fracture shifted to the ductile fracture of the PLA matrix with the inclusion of COPUP [22]. The concept of low cost bio-polyurethane based on castor oil and glycerol with flexible mechanical properties of biomedical applications was studied. Glycerol added as a copolyol will lead to an increase in crosslinking within the backbone of the polymer further lead to enhance the mechanical properties of the polymer. Studies show that polyurethanes derived from castor oil were not toxic to cells [23]. Castor oil and 1,6hexamethylene diisocyanate (HDMI) based polyurethanes were synthesized using different castor oil weight ratio and HDMI. The prepared PU films were thermally stable with a decomposition temperature higher than 300 o C. For rigid and inelastic PUs, higher HDMI content is needed, while low HMDI content PUs was soft and flexible. Polyurethanes with wide range of physical properties were established [6]. Castor oil-based waterborne polyurethane with sodium alginate with CaCl2 aqueous solution treatment was prepared. No chemical modification

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is required for castor oil before its use as a polyol content. This method provides a non-invasive and efficient approach for bio-based polymer composites with superior properties in the application of environmentally friendly coatings and inks. Also, the properties of emerging PUs can be changed by selecting castor oil with a different hydroxyl number and controlling the molar ratio of OH: NCO. The composites exhibited good thermodynamic properties, water resistance and mechanical properties, and represents a better candidate in place of petroleum-based polyurethanes [24]. Castor oil was used as a source of polyol with expanded graphite (EG) to prepare electrical conductive polyurethane foams. The cross-linking density is at risk in the company of EG and the small reactivity of the secondary hydroxyl groups of CO. The mechanical properties are good at 0.5% EG loading while the thermal and electrical conductivities are very low. Superior physical properties were found for loadings around 1 and 1.25%. EG loadings have also been systematically increased thermal and electrical conductivity. For this fillers loading the outstanding physical properties such as glass transition temperature and the Young's modulus are suitable for standard applications [25]. Two different catalysts γ-alumina and formic acid, used for the epoxidation of castor oil, for the conversion of a double bond to oxirane. The epoxidized and saponified castor oil is used as polyol for the preparation of WPU. There was a significant effect of OH number, as well as molecular weight in the viscosity of polyols. The cross-link density is increased by the reaction of hydroxyl groups in the fatty acid chain of castor oil, and has the lowest Tg, because of castor oil act as a chain lubricant [26]. Polyurethanes with varying concentration of castor oil were studied for biomedical application. Their curing time at the surface is: ≤60s, and between 7-25 min for complete curing, facilitate their use in surgeries. The amalgamation of plant oil into the polymer can be used as the surgical adhesive for soft tissue, with suitable and non-harmful properties. Hence such type of castor oil based adhesives can surpass the present bioadhesives [27]. Bio-based polyurethane blends were prepared using castor oil, PPG, phosphorous, phthalic anhydride, and isophorone diisocyanate.

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The blends were studied for flame retardant properties using thermal degradation and LOI. There was 30-40% decrease in the thermal degradation rate in the polyurethane blends. There is an increase in the hydrolytic stability with an increase in the castor oil in polyurethane. Soil burial test confirms that that increased castor oil content reduces bacterial invasion in the polymer chains [28]. Castor oil therefore, contains an active hydroxyl group (−OH) in its structure that can be used as a polyol and is therefore widely used in many chemical industries, especially in the production of polyurethanes by reaction with various diisocyanates [9, 29]. Because of its low cost, low toxicity, and easy availability, castor oil is a promising raw material. The composition of castor oil has a wide range of commercial uses and has the main constituent as hydroxyl group containing ricinoleic acid. Thus castor oil is used as a trifunctional polyol without any chemical alteration for the synthesis of polyurethanes [10]. Castor oil gaining considerable attention as a raw material because of its vast importance over other vegetable oils available [30] and materials like lignin and cellulose. Being renewable, non-toxic, and low cost, and non-food intake thus the food supply has not been compromised [12, 31].

2. FILLERS FOR POLYURETHANE The application of PU in coatings poses a risk as PU is combustible. The major limitation of PU in such an application is the poor fire safety, early aging, and production of large amounts of toxic fumes, load-bearing by-products on burning [32]. The use of flame retardants to improve PU properties has been well recognized. Flame retardants (FRs) fillers are used to reduce flame production during the fire. In general, they are added to materials such as fabrics, plastics coatings and surface finishes slowing down the burning process in case of fire. The base material can be possibly customized in two different ways by adding flame retardants or chemically bonding it to the polymer. The organohalogen and organophophorous compounds can be either additive or reactive, while FRs based on minerals

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are usually additive. Both non-halogenated and halogen solutions are considered but the PU industry seems to prefer non-halogen products, usually containing phosphorus [33]. Due to growing interest in halogen-free flame retardants, there is predominance of phosphorus-based flame retardants. Bridged aromatic diphenyl phosphates, especially resorcinol bis(diphenyl phosphate) and bis(diphenyl phosphate) have found widespread use due to their good thermal stability, high efficiency, and low volatility [34]. Metal salts of dialkylphosphonic acid and calcium hypophosphite, has recently been used effectively for poly (butylene terephthalate) and polycarbonate. These products are associated with a wide range of chemicals containing phosphorus and nitrogen, such as melamine salts, which appear to be very effective and commercially viable for nylon [35]. The most effective FRs compounds contain both phosphorus and nitrogen. Properties like crystallinity, solubility, bioactivity and surface characteristics can be controlled, and the use of the material as a nonburning FR depends upon above listed properties. Organoclay, carbon nanotubes, and polyphosphazenes like FRs have been investigated for their thermal and decay behavior [36]. Primarily, fillers were used to reduce the production cost for polyurethanes. Nowadays, however, FR has become an essential component in numerous applications, mainly to enhance the mechanical properties of PU [37]. Reinforced PUs shows a spectacular transformation in stress at a given strain above the pure polymer [38, 39]. With higher interfacial interactions at the nanolevel, the material in the nanometer range emerged as striking candidates as fillers. Carbon nanotubes have attained great concern due to their extraordinary properties such as multiwalled structure, good electrical conductivity, and high strength. The tensile strength for carbon nanotubes is about 20 times more than that of high strength alloys. The carbon nanotubes exhibit extraordinary mechanical as well as thermal properties [40, 41]. The major applications of nanoclay and carbon nanotubes are listed in Figure 4.

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Figure 4. Applications of nanoclay and carbon nanotubes as fillers.

3. FABRICATION OF POLYMER NANOCOMPOSITE The fabrication of CNTs/polymer nanocomposite mainly focuses on the advanced dispersion of nanotubes in the polymer matrix, as pristine nanotubes do not disperse in polymers due to their high difficulty in overcoming the natural thermodynamic tendency to form bundles. There are three methods of producing CNT/polymer nanocomposites:   

Solution Blending Melt Blending In situ polymerization

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3.1. Solution Blending In this process of formulating polymer nanocomposites, there are three main steps: (i) dispersion of nanotubes in a suitable solvent (ii) polymer mixing and (iii) film casting. There is difficulty in dispersing the pristine nanotubes into the solvent by simple stirring. Therefore, the ultrasonication method can be used to make uniform suspensions of nanotubes in different solvents. Prolonged ultra-sonication time breaks down the nanotubes in smaller lengths, hence reduces the aspect ratio affecting the composite properties. The smallest sonication conditions for time and power to produce CNTs degradation are not determined to date [42].

3.2. Melt Blending Melt blending is the preferred method for preparing clay/polymer thermoplastic and elastomeric polymeric nanocomposites. The process uses high shear forces at elevated temperature to disperse the CNTs into the polymer matrix [43]. This process is well-suited for current industrial practices. While in comparison to the solution blending method, this method is less useful. Because the dispersion of CNTs into the polymer is limited by lower concentration and high viscosities of polymer composite by higher CNTs loadings. Melt blending is environmentally benign due to the absence of organic solvents. Melt blending is compatible with current industrial processes, such as extrusion and injection molding [44, 45].

3.3. In-Situ Polymerization The in situ polymerization technique is the traditional method for processing polymer nanocomposites. The general principle of this fabrication method involves the mixing of the nanofiller with the monomers in a solvent, followed by in situ polymerization. It has been used successfully to produce polymer/layered silicate nanocomposites with

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an exfoliated structure, and due to the similar layered structure of GE, this method was also employed for the preparation of GE/elastomer nanocomposites [46]. The nanotubes are dispersed into the monomer and then polymerization takes place. Solution blending method, functionalized nanotubes can be used to improve the dispersion of nanotubes in the monomer or solvent. In addition to this in situ polymerization method facilitates covalent bonding between functionalized nanotubes and polymer matrix using different condensation reactions [47]. There are two methods for the fabrication of polymer/CNT composites: first by direct incorporation of functionalized CNTs into polymer matrices or generally known as a non-covalent attachment and second one is in situ polymerization at their surface or covalent attachment [48-50].

4. NANOCOMPOSITES Nanocomposites are materials that integrate nanoparticle into the matrix material. The result of the introduction of nanosized particles brings significant improvement in the characteristics that may include resilience, mechanical strength, electrical and thermal properties. The nanocomposites conceptualize to create a huge interface between the polymer matrix and the nanosized building blocks [51]. They have great potential in almost all industrial sectors due to enhanced thermal, electrochemical, optical, biomedical properties. Also, they have been extensively used in drug delivery systems. Through transdermal route, the drug molecules penetrate into the skin. In this route nanocomposites have incredible application possibilities [52]. New nanomaterials/nanoscale materials have been studied and synthesized for industrial, biomedical, pharmaceutical, packing and coating etc. With technological advances, the biomedical nanocomposites are manufactured for miscellaneous sectors like tissue engineering, wound healing, cardiac prosthesis, biosensors [53]. Chitosan based nanocomposites provide potential application in the field of biomedical

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and pharmaceutics. The physical and biological characteristics of chitosan have attracted much attention because of its biodegradability. The novel features can be introduced to chitosan as it has good efficiency for chemical and mechanical properties by structural functionality. Versatile chitosan derivatives can be fabricated by using material technologies. which found numerous applications in the field of biological engineering [54]. MWCNT are the potential candidates for synthetically engineered bone implants by an in-depth review of the consequences of the preparation process, concentration and impact on the performance of MWCNT based biocomposites with polymer, bioglass and hydroxyapatite. Their contrasting experiment with each other and toward traditional composites made up of polymer, metals and ceramics. MWCNT, therefore, presents it as a dynamic biomaterial for the improvement of long-term bone tissue with significant mechanical and electrical properties [55]. Nanocomposites can be used in the form of coatings that act as a powerful barrier to gas as well as solvent and can be used for packaging applications. The use of nanocomposite in the exfoliated structure effective path length for the diffusion of molecule in between the inorganic filler increases and hence forces the penetration of solvent molecules to follow the tortuous path. Reduces the effective transfer of the gas and solvent molecule through the film [56]. Some of the major applications of the nanocomposites was shown in Figure 5. Polymer nanocomposites (PNC) have attracted a numerous commercial attention with their exciting applications available from energy storage, sensing and actuation, thermal flow control and transport protection systems. PNC usually consists of nanoparticles/nanofillers dispersed in a polymer matrix. They have different shapes and geometry for example fibers, spheroids and platelets with dimensions in the range of 1-100 nm. Physiochemical properties are found in nanocomposite which can be expressed by individual components only [57]. The classification of nanocomposites can be done based on components added to the nanocomposite as shown in Figure 6.

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Figure 5. Some major applications of nanocomposites [57].

Figure 6. Classification of nanocomposites [58, 59].

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Typically, nanocomposite material is composed of a matrix and reinforcing fibers. The matrix comprises a resin with filler to achieve the enhanced characteristics of the resin at the same time decreasing the cost of production. The homogeneous material is built by the composition of resin and the filler. The reinforced filler provides the matrix with higher mechanical characteristics. The function of the matrix is to transmit the external load to the fiber and to guard the fiber from exterior mechanical load and external attack. Polymer based nanocomposite can also be classified as: Based on the kind of filler, i.e., the nanoscale material of the nanocomposites, for sensing applications, they are divided into:    

Metal oxide–metal oxide–based nanocomposites, Polymer-based nanocomposites Carbon-based nanocomposites, Noble-metal–based nanocomposites

Non polymer based nanocomposites such as Metal/metal nanocomposite, Metal/Ceramic nanocomposite, and Ceramic/Ceramic nanocomposite are also present and used. While polymer based nanocomposites like Polymer/Ceramic nanocomposite, inorganic/Organic Polymer nanocomposite having unique properties due to their large aspect ratio and sub-micrometer size. They can find applications in nanosensors, nanoprobes, and other chemical and biological analysis. They also possess applications in catalysis, separation, sorption, and fuel cells [60]. The polymer based nanocomposites are composed of filler reinforced in the polymer matrix and have a dimension of less than 100nm. These fillers can be high-quality composite clay, or nanotubes, or other nanoparticles that can enhance the properties of the nanocomposites. Some other kinds of polymer nanocomposites are: I.

Polymer/ceramic nanocomposite: they consist of a single ceramic layer generally ~ 1nm and homogeneously dispersed in the matrix. Due to the dipole-dipole interaction, the coated ceramic layer tends

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II.

III.

IV.

V.

VI.

to orient parallel to each other. For example, in the case of natural bones, the 30% matrix is collagen and 70 % nanosized mineral. Inorganic/ Organic polymer nanocomposites: they have unique properties of the metal group dispersed in the polymer matrix. Their size varies from 1-10 nm. The properties of the nanocomposite are very different from the basic material and the individual atoms. For example, in the case of polymethyl methacrylate (PMMA) polymer the cluster size depends on the quantity of the cross linking of the polymer, which changes the mobility of the metal atoms. Inorganic/Organic hybrid nanocomposite: Hybrid inorganic/ organic materials are not just physical combinations, but they can be fundamentally diverse nanocomposites with organic and inorganic components thoroughly mixed. Hybrids are more homogenous systems resulting from monomers and miscible organic/inorganic components, or diverse systems nanocomposites where at least one of the components has the scale of a nanometer. Polymer/Layered silicate Nanocomposites: Polymer/Layered silicate (PLS) nanocomposites materials receive significant attention in polymer science research. Hectorite and montmorillonite are among the smectite-type-layered silicates for the synthesis of the nanocomposites. Polymer/polymer Nanocomposites: Polymers are under pressure to crack and disperse material profiles. The difference between the block co-polymer self-assembly and the proposed nanostructured polymer here with non-available variations of properties is decreasing. Mixtures of different polymers are usually separated separately, even if their monomer is mixed together. Biocomposites: Metals and metal alloys used in orthopedics, dentistry and other load bearing applications. Ceramics are used prominently in their non-chemical environment or in high bioactivity. All polymers are used for soft tissue replacements and used for other nonstructural application [58, 59, 61].

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CONCLUSION With the growing demand for nanomaterials and nanotechnology, the demand for naturally occurring vegetable oils is increasing. The vegetable oils can be used as such or need very little modification for various applications. Also, they are cost effective and efficiently replace the conventional nonrenewable mineral oil resources. Different techniques and methods mentioned above can be incorporated for the production of a wide range of products. The products found numerous commercial applications in the field of polymers, nanotechnology, biomedical, paints and coatings. This chapter focus on the preparation of hybridized PU nanocomposites using dehydrated castor oil as basic raw material. For preparing the nanocomposites with enhanced features various fillers can be rereinforced like cloisite clay and MWCNTs. After the addition of clay and MWCNTs the properties of matrix enhanced significantly as reported in the literature. The excellent properties of both the fillers can be used to produce nanocomposite for different applications. There is an overall improvement in morphological and mechanical properties of the nanocomposites synthesized from vegetable oil based polyols. Also, they don’t pose any serious hazard to human and environment. So these vegetable oils can be considered as the potential source of polyols for various polymeric reactions for varied commercial applications.

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[35] Horacek, H. and R. Grabner, Advantages of flame retardants based on nitrogen compounds. Polymer Degradation and Stability, 1996. 54(2): p. 205-215. [36] Chen, T. K., Y. I. Tien, and K. H. Wei, Synthesis and characterization of novel segmented polyurethane/clay nanocomposites. Polymer, 2000. 41(4): p. 1345-1353. [37] Yang, R., et al., Synthesis, mechanical properties and fire behaviors of rigid polyurethane foam with a reactive flame retardant containing phosphazene and phosphate. Polymer Degradation and Stability. 122: p. 102-109. [38] Ma, J., S. Zhang, and Z. Qi, Synthesis and characterization of elastomeric polyurethane/clay nanocomposites. Journal of Applied Polymer Science, 2001. 82(6): p. 1444-1448. [39] Barikani, M., F. Askari, and M. Barmar, A Comparison of the Effect of Different Flame Retardants on the Compressive Strength and Fire Behaviour of Rigid Polyurethane Foams. Cellular Polymers, 2010. 29(6): p. 343-358. [40] Xiong, J., et al., The thermal and mechanical properties of a polyurethane/multi-walled carbon nanotube composite. Carbon, 2006. 44: p. 2701-2707. [41] Chen, W., X. Tao, and Y. Liu, Carbon nanotube-reinforced polyurethane composite fibers. Composites Science and Technology, 2006. 66(15): p. 3029-3034. [42] Tang, L.-C., et al., Chapter Twelve - Mechanical Properties of Rubber Nanocomposites Containing Carbon Nanofillers, in CarbonBased Nanofiller and Their Rubber Nanocomposites, Elsevier. p. 367-423. [43] Jin, Z., et al., Dynamic mechanical behavior of melt-processed multiwalled carbon nanotube/poly(methyl methacrylate) composites. Chemical Physics Letters, 2001. 337(1): p. 43-47. [44] Zhang, M., et al., Recent advances in the synthesis and applications of graphene polymer nanocomposites. Polymer Chemistry. 6(34): p. 6107-6124.

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[45] Rane, A. V., et al., Chapter 5 - Methods for Synthesis of Nanoparticles and Fabrication of Nanocomposites, in Synthesis of Inorganic Nanomaterials, Woodhead Publishing. p. 121-139. [46] Ivanoska-Dacikj, A., et al., Chapter Two - Fabrication Methods of Carbon-Based Rubber Nanocomposites, in Carbon-Based Nanofiller and Their Rubber Nanocomposites, Elsevier. p. 27-47. [47] Fim, F.d.C., et al., Polyethylene/graphite nanocomposites obtained by in situ polymerization. Journal of Polymer Science Part A: Polymer Chemistry. 48(3): p. 692-698. [48] Hwang, G. L., Y. T. Shieh, and K. C. Hwang, Efficient Load Transfer to Polymer Grafted Multiwalled Carbon Nanotubes in Polymer Composites. Advanced Functional Materials, 2004. 14(5): p. 487-491. [49] Baibarac, M., et al., Polyaniline and Carbon Nanotubes Based Composites Containing Whole Units and Fragments of Nanotubes. Chemistry of Materials, 2003. 15(21): p. 4149-4156. [50] Chen, J., et al., Noncovalent Engineering of Carbon Nanotube Surfaces by Rigid, Functional Conjugated Polymers. Journal of the American Chemical Society, 2002. 124(31): p. 9034-9035. [51] Hari, J., B. Pukazky, and M. Kutz, 8 - Nanocomposites: Preparation, Structure, and Properties, in Applied Plastics Engineering Handbook, William Andrew Publishing: Oxford. p. 109-142. [52] Parhi, R., et al., 16 - Nanocomposite for transdermal drug delivery, in Applications of Nanocomposite Materials in Drug Delivery, Woodhead Publishing. p. 353-389. [53] Hasnain, M. S., et al., 7 - Nanocomposites for improved orthopedic and bone tissue engineering applications, in Applications of Nanocomposite Materials in Orthopedics, Woodhead Publishing. p. 145-177. [54] Ahmad, M., et al., 11 - Chitosan-based nanocomposites for cardiac, liver, and wound healing applications, in Applications of Nanocomposite Materials in Orthopedics, Woodhead Publishing. p. 253-262.

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[55] Perveen, R., et al., 5 - Multiwalled carbon nanotube-based nanocomposites for artificial bone grafting, in Applications of Nanocomposite Materials in Orthopedics, Woodhead Publishing. p. 111-126. [56] Oriakhi, C. O., M. M. Lerner, and R. A. Meyers, Nanocomposites and Intercalation Compounds, in Encyclopedia of Physical Science and Technology (Third Edition). 2003, Academic Press: New York. p. 269-283. [57] Delides, C., Everyday Life Applications of Polymer Nanocomposites2016. [58] Mourino, V. and H. Liu, 8 - Polymer nanocomposites for drug delivery applications in bone tissue regeneration, in Nanocomposites for Musculoskeletal Tissue Regeneration, Woodhead Publishing: Oxford. p. 175-186. [59] Venkatachalam, S., et al., Chapter 6 - Ultraviolet and visible spectroscopy studies of nanofillers and their polymer nanocomposites, in Spectroscopy of Polymer Nanocomposites, William Andrew Publishing. p. 130-157. [60] Pandya, S., Nanocomposites and its application-REVIEW. [61] Camargo, P., K. G. Satyanarayana, and F. Wypych, Nanocomposites: Synthesis, Structure, Properties and New Application Opportunities. Materials Research-Ibero-American Journal of Materials - MATER RES-IBERO-AM J MATER, 2009. 12.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 4

POTENTIAL HEALTH BENEFITS OF VEGETABLE OILS

Amandeep Singh, Muskaan Kamboj and Shilpi Ahluwalia *

Dr SS BUICET, Panjab University, Chandigarh, India

ABSTRACT Oil derived from plants has been used for food-based applications all around the world. Plant oils have a varied range of fatty acids and being a non-polluting renewable resource, they are extensively used for industrial applications. Fatty acids (FAs) play a significant role in human nutrition which includes growth and development of human embryo, brain function and safeguard our body against many serious diseases such as cardiovascular, cancer, inflammation etc. Vegetable oils consist of important fatty acids like saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) and their fatty acid composition varies with the source plant and technology used during their manufacturing process. Thus, vegetable oils confer unique physico-chemical properties which make them extremely useful. In this chapter the source, composition, nutritional value, and health benefits of various vegetable oils have been discussed. *

Corresponding Author’s E-mail: [email protected].

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INTRODUCTION Oil has been an integral part of our food supply for thousands of years. In the past century, the consumption of vegetable oils has been increasing because of technological advances in their extraction techniques (Loren et al., 2005). Vegetable oils are the oil produced from various plants which can be further categorized as oils extracted from different oilseeds (e.g., mustard seed and cotton seed), legumes (e.g., groundnut and soybean), nuts (e.g., almond and walnut) and some fruits (e.g., olives). The vegetable oil is extracted from the plants using a solvent which is then processed and refined to remove undesirable components such as solvent, dust, water and trace elements like copper, iron, sulphur etc. to obtain high-quality oil which can be used for commercial applications. Various methods have been used for the extraction of oil which includes some traditional and conventional methods like solvent extraction (using solvents like hexane, petroleum ether, ethanol, diethyl ether etc.) and advanced innovative techniques like ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE), supercritical fluid extraction (SFE). However, conventional methods have disadvantages of prolonged extraction times, larger solvent consumption and adverse thermal effects at high temperatures whereas newer technologies have been developed to effectively reduce these shortcomings to produce high quality oil (Karmakar and Halder, 2019). Vegetable oils are an important part of our daily diet because they provide us with fats which are an important source of energy (Vaskova and Buckova, 2015) and play a role in production of several hormones in our body like testosterone etc. Alteration in lipid metabolism may cause disruption of signaling networks which may be led to some pathological conditions like cancer, cardiovascular diseases, neurodegenerative, metabolic diseases, and inflammatory problems (Jana et al., 2015). Vegetable oils are primarily composed of triacyl glycerides (TAGs, also called triglycerides which have three fatty acids on glycerol), so mainly they supply fat to our body. Other than fat, nutrient which is present in significant amount is vitamin E, though some fats available in market are fortified with vitamins D and A.

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Along with this, some minor components present in vegetable oils include free fatty acids, mono & diglycerides, sterols, phosphatides, fatty alcohols, and various bioactive compounds. The high nutritional value and vast health benefits of vegetable oils could be attributed to their individual constituents such as fatty acid composition and several types of natural antioxidants present in them such as vitamin E, vitamin A and carotenoids that give protection to cells and tissues from damage by free radicals. Recently, nutritionists have suggested the use of oils in our diet besides their traditional sources (such as algae and fish oil) from vegetable oil because of their high fatty acids (FAs) content. They are recommended as substitute to sources of saturated fat such as butter, lard and tallow and often tagged as “heart-healthy” because of the presence of polyunsaturated fats. Regardless of their potential health benefits, scientists are working upon the amount of oil necessary for the human body. This chapter briefly explains the nutritional value of the various vegetable oils and the contribution of each oil in making our diet balanced and healthy.

COCONUT OIL Cocos nucifera, the plant from which coconut oil is extracted is grown extensively in parts of South East Asia and Southern India. The Philippines is the main producer of coconut oil, followed by Indonesia and India. Coconut oil is extracted from the fruit of Cocos nucifera plant i.e., coconut. The fruit of the plant is also called a drupe. The dried kernel of the coconut i.e., Copra, is the main part from which the oil is extracted. Belonging to the category of lauric oils, it is obviousevident that coconut oil also consists of lauric acid. Apart from free fatty acids and triglycerols, coconut oil also contains 0.5% of unsaponified matter. It consists of sterols, tocols, squalene, color compounds, carbohydrates, and lactones. Lactones are odorous compounds that give a characteristic smell to coconut oil. Being a lauric oil, coconut oil has prominent level of short and medium chain fatty acids, particularly characterized by C6 -C14 length

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chains. These types of fatty acids encompass 80% of all fatty acids found in coconut oil, compared to less than 2% in non-lauric oils. To be more specific, lauric acid accounts for 50% of fatty acids in coconut oil. Historically in various researches it has been concluded that triglyceride content of coconut oil consists of 84% tri-saturated, 12% di-saturated, 4% mono-saturated triglycerols. Medium chain fatty acids and polyphenolic compounds are the key components of coconut oil that has health benefits in humans. (Pantzaris and Yusuf, 2002)

Health Benefits of Coconut Oil It is claimed that coconut oil plays a crucial role in preventing and treating Alzheimer’s disease (AD) which accounts up to 70% of dementia cases. AD is a neurodegenerative disorder which is seen in the elderly and can be very fatal. Till now no such diagnostic tool or treatment method has been devised for it and the factors that lead to neuronal dysfunction are still under investigation. For a normal synapse to function properly an enormous number of coordinated biochemical processes are required for which a continuous supply of energy is needed. Most of this energy is acquired from the aerobic oxidation of glucose in mitochondrion of cells and this free energy fuels all the reactions occurring in the brain. Any disruption in this glucose metabolism may prove to be catastrophic and can cause synapse dysfunction (Mosconi and Leon, 2009). According to various reports, hindered glucose metabolism is one of the early symptoms of AD. It can thus be used as an early sign of dementia and AD like diseases. Abundant amount of medium chain fatty acids in coconut oil produce ketone bodies on being metabolized. These bodies can act as an alternate source of energy for the brain whose glucose metabolism is hindered and becomes oxygen deficient. Coconut oil and its derivatives thus can prove effective in the prevention of AD at an early stage (Chatterjee et al., 2020). Numerous studies also point out the antimicrobial and anti-viral nature of medium chain fatty acids. Such fatty acids and other monoglycerides cause lysis of bilipid plasma membrane,

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thus killing the microbe. The antiviral effect is seen because of disintegration of the envelope of virus (Enig, 1999).

CANOLA OIL/RAPESEED OIL Rapeseed is a plant belonging to the Brassicaceae family and is characterized by bright yellow flowers. Prior to 1976, rapeseed oil was primarily used for industrial purposes, since it contains extremely high proportions of Euric acid. However, some Canadian scientists were able to improve the cultivar in the year 1976 through traditional plant breeding methods thus, developed the consumable canola cultivars. Thus, canola oil can be named as a variety of rapeseed oil, having low euric acid and lowglucosinolate content. It is to be noted that both these compounds are claimed to have a negative effect on human health (Lin et al., 2013). China, EU, India, Canada, and Japan are the leading producers of canola oil and the US is the largest importer of this oil (Gunstone, 2002). On an average euric acid constitutes less than 2% of total fatty acids of canola oil and the level of glycosylates is capped at 30 µmol/g (Przybylski and Mag, 2002). Overall canola oil has lower amount of saturated fatty acids, constituting around 7% of the total fatty acid content present. Thus, an appreciable amount of unsaturated fatty acids is present in it (this includes both MUFA AND PUFA), out of this, oleic acid is 61%, linoleic acid 21% and alpha-linolenic acid 11%. In addition to this, canola oil also contains plant sterols ranging from 0.53–0.97% and tocopherols 700– 1,200 ppm (Lin et al., 2013).

Health Benefits of Canola Oil Comparing canola oil with other oils having high content of unsaturated fatty acids, the following conclusions can be made. The extent to which the canola oil and sunflower oil reduces the total cholesterol (TC) content was found to be the same. Taking olive oil as control oil, three

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studies showed that canola oil performed better to reduce the TC content in consumers. Results showed that there was reduction in TC concentration by 12.2%, 14.0%, and 11.6% after consumption of canola oil when compared to olive oil. Compared to corn oil, canola oil was able to reduce TC concentration by 5.4% in a study done by Lichtenstein et al. (1998). A study by Truswell and Choudhury (1993) also showed that canola oil may have better effects in regulating the level of LDL-C when compared with olive oil as the control oil. (Lin et al., 2013)

SUNFLOWER OIL Obtained from the seeds of Helianthus annuus, sunflower oil is one of the four major fats and oils in the world. After soybean, palm, and canola oil, sunflower oil is the largest oil resource in the world. The former USSR area, EU-15, and Argentina are the leading producers of sunflower oil, with Argentina being the largest exporter of this oil (Gunstone, 2002). Sunflower oil can be categorized into three depending on the oil content. The traditional sunflower oil is majorly composed of PUFA (linoleic acid), 65-70% of such oils consists of linoleic acid alone (Figure 1). High-oleic sunflower oil consists of more than 80% oleic acid (MUFA) while mid-oleic sunflower oil consists of 55-75% of oleic acid (MUFA) and 15-35% linoleic acid (PUFA). Other compounds that are found in the sunflower oil include tocopherols, phospholipids, carotenoids and some amount of plant sterol and stanol esters (Foster et al., 2009).

Health Benefits of Sunflower Oil Elevated levels of linoleic acid (PUFA) are linked with the reduced risk of cardio vascular diseases (Foster et al., 2009). A recent study conducted on healthy rats showed that sunflower oil helped in reducing the level of serum cholesterol and triacylglycerol (TAG) (Gomes et al., 2020). Superoxide dismutase (an antioxidant) is an enzyme whose role is to

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breakdown the potentially harmful molecules of oxygen and thus plays a vital role in protecting cells from getting damaged. In a study conducted by Gomes et al. (2020) on healthy rats showed that consuming sunflower oil over a prolonged period increases the superoxide dismutase activity.

Saturated fat

Monounsaturated oil

Rice bran oil

Peanut oil

Palm oil

Olive oil

Soybean oil

Sesame oil

Flaxeed oil

Sunflower oil

Canola oil

Coconut oil

100 90 80 70 60 50 40 30 20 10 0

Polyunsaturated oil

Figure 1. Fatty acid composition of different vegetable oils.

FLAX SEED OIL Flaxseed oil popularly known as linseed oil is derived from seeds of flax plant (Linum usitatissimum) and has been widely used for non-cooking purposes. In recent times it has become a well-known oil for its health promoting properties and is being used as a dietary supplement (Foster et al., 2009). Flax crops are produced in sub-tropical areas; which including Canada, Argentina, India, US, China, and some European countries, Canada, however, is the largest producer and exporter. Flaxseed oil contains an elevated level of PUFA (66%), which primarily consists of alpha linolenic acid (Foster et al., 2009). This fat acid oxidizes very easily, which justifies the reason for not using this oil for cooking purposes. Other components of flaxseed oil include the usual sterols and tocopherols (440– 588 mg/kg of tocopherol). The primary tocopherol found in flaxseed oil is the γ-tocopherol (Kochhar, 2002).

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Health Benefits of Flaxseed Oil Flaxseed is also known to be a potential source of plant lignans that are defensive against hormone related prostate, breast, and colon cancer. (Kochhar, 2002). In case of flaxseed oil, prominent level of α-Linolenic acid (ALA) is linked with the reduction in occurrence of cardio-vascular diseases (Foster et al., 2009). In another research, the effect of flaxseed oil on 30 hypercholesterolemia patients was studied. After taking two capsules of flaxseed oil daily for 6 months, more than 43% of patients received good response and 40% of patients got moderate response (Sharma, 2012).

SESAME SEED OIL Sesame seed oil is obtained from the seeds of Sesamum indicum. Sesame is one of the oldest oil-seed crops cultivated by humans. From time immemorial sesame seeds are valued for its properties such as high oil content (42-56%). Sesame oil has a good amount of proteins and minerals which has led to the claims to offer a variety of health benefits. However, the exact oil content of seed depends on the types of processing they go through. Largest producers of sesame seed oil include India, China, Myanmar, Sudan, and Mexico (Kochhar, 2002). Sesame oil has 85% unsaturates and 15% saturates. The unsaturates can further be divided into 45% PUFA (containing LA and ALA) and 40% MUFA (Foster et al., 2009). Sesame seed oil also contains chemical compounds like sterols, tocopherols, and sesame lignans (sesamin, sesamolin etc.) which have unique antioxidative property.

Health Benefits of Sesame Seed Oil Due to the presence of antioxidative materials, sesame oils have been used for anti-aging purposes and to prevent various other diseases. It is also claimed that sesame oil plays an active role in physiological

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suppression of lipid peroxidation. A comparative small-scale study of sesame oil and coconut oil conducted on type 2 diabetes patients showed that the fasting blood sugar level was lowered by an appreciable amount and the blood lipid profile also improved in the patients who were consuming sesame oil (Foster et al., 2009). Various other clinical trials are underway, to get an in-depth knowledge of the health benefits of sesame oil. A study to observe the effects of sesame (both black and white) consumption on mice was carried out recently in China. It reported that the consumption sesame seeds and its kernel was successful in improving hyperlipidaemia and antioxidant capacity in the liver and also reduced the risk of fatty liver (Li et al., 2020).

SOYBEAN OIL Soybean oil is one of the most widely used cooking oil which is extracted from soybean (Glycine max). China has been using and producing soybean oil from beans since 2000 (according to some old Chinese records) and is still a major producer of soy oil other than the US, Brazil, and Argentina. Its composition includes many monounsaturated fats, polyunsaturated fats, omega-3 fatty acids, the major ones are linoleic acid (51%), oleic acid (23%), palmitic acid (10%), α-linolenic acid (710%) and stearic acid (4%). Out of this, α-linolenic and linoleic acid are polyunsaturated and oleic acid is a monounsaturated, whereas stearic and palmitic acid are saturated fatty acids which are present in comparatively lesser proportions. Crude soybean oil has significant amounts of phospholipids and unsaponifiable matter (1.6%) and is also rich in vitamins like vitamin K and vitamin E (Chuffa et al., 2014 and Wang, 2002). Soybean oil has a mild, neutral taste that can fit seamlessly into any recipe that calls for cooking. It has high smoke point of 230°C due to which it can withstand high temperature without breaking down, that is the reasonit can be used in variety of cooking methods including frying, baking, roasting and sautéing.

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Health Benefits of Soybean Oil Due to the incredible versatility of soybean oil, it has many potential health benefits and various other applications. As soybean oil is rich in vitamin K, it helps in maintaining bone strength and reducing the risk of fractures. According to one animal report, it has helped in preventing bone loss (Akbari and Ghahroudi, 2018). While vitamin K is perhaps best known for its effect on blood clotting, it also plays a vital role in regulating bone metabolism (Wang, 2002). Vitamin E is an antioxidant and fatsoluble vitamin, which helps in maintaining the integrity of the cell membranes and prevents the harmful damage of harmful oxygen-free radicals (Chuffa et al., 2014) The consumption of soybean oil also has heart healthy benefits because of the presence of polyunsaturated fatty acids. α-linolenic acid, is beneficial for heart and is associated with lowering cholesterol levels and risk of heart disease. The intake of soybean oil in diet acts as an immunity booster and helps in preventing many chronic diseases. This effect can be attributed to omega-3 fatty acids like oleic acid, which play a key role in promoting immunity (Wang, 2002).

OLIVE OIL Olive oil is a liquid fat derived from olives i.e., the fruit of Olive tree (Olea europaea, family Oleaceae). It is the major source of fat in the Mediterranean area, and sets apart from other regimens due to its vast benefits, which are due to its composition. The olive oil comprises of triacylglycerols (about 99%), along with this it also consists of free fatty acids, mono and di-glycerols and some lipids such as tocopherols, aliphatic alcohols etc. Also, some phenolic and volatile components present are responsible for unique characteristics of this oil. Fatty acids are essential and the most beneficial part of olive oil. The most common fatty acids present in olive oil are oleic acid, linoleic acid, palmitic and stearic; but the percentage of fatty acids vary with the variety and their cultivation. Also,

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olive oil is rich in unsaturated fats majorly (about 85%), particularly MUFA, which makes it healthier (Visioli et al., 2018; Boskou et al., 2006).

Health Benefits of Olive Oil Consumption of Olive oil is increasing with time due to its health benefits, which are majorly due to the bioactive compounds present in it, including polyphenols, tocopherols, and carotenoids. Many ecological studies have related the Mediterranean diet (considering olive oil as the major source of fat) with vitality (and/or lastingness) and lesser prevalence of heart diseases, diabetes and cancer. Olive oil consumption, especially Extra Virgin Olive Oil (EVOO, an essential type of olive oil), is useful for chronic non-communicable diseases (NCD) due to two factors; first being the higher amounts of various bioactive components including phenolic compounds (i.e., polyphenols). Phenolic compounds are related more to the stability of oil than its biological properties. More oxidative stability of edible oil indicates its usefulness and lesser adverse effects on health. Second factor is the presence of health promoting carotenoids, like βcarotene and provitamin A which is present in abundance (Gavahian et al. 2019). Olive oils from different zones across the world have beneficial effects on the Gut microbiota, as it boosts the growth of beneficial microorganisms. Gut (or intestinal) micro biotas are the micro-organisms living in the digestive tracts of humans, and have important roles in our digestive and immune systems. Furthermore, intake of EVOO is recommended as it is found to be very beneficial in preventing diseases like type-2 diabetes and cancer. This is because of the reason that this form of olive oil includes higher proportions of MUFAs and a balanced composition between PUFAs and other minor components such as phenolic compounds, which further increase its antioxidant potential (Foscolou et al., 2018). Apart from this, low polyphenol olive oils lower the amount of saturated fats in our diet, which is also good for our body. Some more positive effects of olive oil include suppression of food-borne pathogens and its antioxidant activity, add up to the long queue of benefits,

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which makes olive oil among the top healthy edible oils all over the world (Visioli et al., 2018).

PALM OIL Palm oil is the global leader in edible oils in relation to its production and trading. It is obtained from the ripe fruits of palm tree (Elaeis guineensis). The ancient tropical plant had originated from West African countries while some of the leading producers of palm oil are Indonesia, Malaysia, Thailand, Columbia and Nigeria. Palm oil contains equal amounts of saturates and unsaturates of which palmitic and oleic acid are present in considerable amounts. Its balanced fatty acid composition is responsible for making it the most versatile oil in the agri-food sector. Crude palm oil is rich in carotenes, tocopherols, sterols and tocotrienols. It is one of the richest sources of vitamin E and pro-vitamin A. The fatty acid composition of palm oil along with some minor components, including anti-oxidants, varies with the conditions of refining (Daud et al., 2012; Ogan et al., 2015). For many centuries, palm oil has been used for food and medicinal purposes. Symbiotic activity of both β-carotene and tocotrienol makes it highly stable, especially during frying, which is another main factor of its extensive usage in food industries. That is why physically stable oils like palm oil or blends of palm oil are used to make most of the benefits from the oils (Ogan et al., 2015).

Health Benefits of Palm Oil According its composition, palm oil contains a rich blend of antioxidants, which are beneficial to diabetic patients because many studies have shown that its pivotal anti-oxidants protect the body by preventing cellular damage due to oxidative stress (Toyin et al., 2020). One of the most used forms of this oil is Red Palm Oil (RPO), which is natural oil, containing natural fat-soluble tocopherols, tocotrienols and carotenoids. It

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is said to have beneficial effects on lipid peroxidation and monocytic tissue factor in HCV- liver disease and significantly affects macrophage-colony stimulating factor. RPO has been most widely researched for its health care benefits, including anti-oxidant activities, cholesterol reduction ability and anti-cancerous effects. It modulates oxidative stress and is recommended as an important nutritional tool for managing chronic liver diseases. Red palm oil can also be used in regional food products to prevent vitamin A deficiency (Catanzaro et al., 2016). Ong and Goh (2002) in their review have therefore suggested not classifying palm oil as ‘saturated fat’. Palmitic acid has a negative effect on cholesterol, whereas oleic acid present have a beneficial effect on factors leading to Coronary Heart Disease (CHD). Thus, palm oil acts like an ‘unsaturated oil’ concerning blood lipid parameters and has comparatively neutral effect on elevated blood cholesterol (Lin, 2002).

PEANUT OIL Peanut oil is extracted from peanuts, i.e., seeds of plant Arachis hypogaea L. Peanut seeds contain about 40-50% of oil, and hence are a rich source of oil fats. Peanut oil production comes at the fifth rank of all plant oils produced worldwide. India and China are the major countries where this oil is extensively used and produced, although its economic importance has increased worldwide over the past many years. It is used in American, Chinese and South Asian cuisines, for general cooking as well as for added flavor. Peanut oil contains 20% saturates, 50% MUFAs and 30% PUFAs (primarily linoleic acid), though the fatty acid profile can vary depending upon the region of origin. This oil is a useful source of vitamin E and contains several sterols, including β-sitosterol, campesterol, stigmasterol and many more (Sanders, 2003; Foster et al., 2009).

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Health Benefits of Peanut Oil As mentioned before, the importance of peanut oil has increased over the past years; this is attributed to its beneficial health effects. Many studies have been conducted to compare different diets and shown that people consuming peanut oil as a part of their diet have shown constant reductions in LDL, total cholesterol and TAG levels. Peanut oil has a high smoke point (229.4 °C) and is thus suitable for deep-fat frying which enables it to cook food quickly; along with lesser oil absorption. The raw crude oil contains a nutty flavor, although this off-flavor is removed after refining, and with prior frying and cooking it can also be used for salad dressings (Foster et al. 2009). Furthermore, the monounsaturated fats present in peanuts are known to be beneficial for the heart. It was found that diets including peanut oil assisted in lowering cardiovascular disease risk by a substantial number of 21% (Rachaputi and Wright, 2015). As mentioned above sterols are prominent part of this oil’s composition, βsitosterol being the major sterol in peanuts, assists in inhibiting cancer growth. It also protects us from some chronic diseases such as colon, prostate and breast cancer (Sanders, 2003). Since oleic and linoleic acids are the major FAs constituting peanut oil, the oil’s quality is determined by the ratio of these two, respectively. A higher ratio leads to improved shelf life and storage quality of the oil (Dwivedi et al., 2013).

RICE BRAN OIL Rice Bran oil (RBO) is a major by-product of rice-milling industry as it is extracted from the ‘Bran’ obtained when the paddy is milled. It has been used for centuries in Asian countries such as China, Korea, Japan, Indonesia, and India. Its fatty acid composition makes it a healthy and includes 75% unsaturated fatty acids, with Linoleic acid and Oleic constituting the major percentage, and 25% saturated fatty acids. Other components that are present in rice bran oil are tocopherols, tocotrienols and phytosterols. γ-oryzanol is also a component of rice bran oil present at

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around 2% of crude oil content. It is a group of ferulic acid esters of triterpene alcohols and plant sterols, and shows antioxidant as well as biological activity, though, the composition of the oil varies with the factors such as the region of its origin or level of refinery (Lai et al., 2019; Kochhar, 2002). Rice bran oil is an edible oil used widely in South Asian countries, more as ‘healthy oil’ rather than ‘cooking oil’. The oil has particularly good oxidative stability, due to the cumulative effects of phytosterols, oryzanol, tocopherols and tocotrienols. Also, it gives a pleasant flavor to fried food. This makes RBO the perfect choice for frying high quality products, particularly for foods with delicate flavors. It is also used as salad oil due to its flavoring factor (Lai et al., 2019). RBO containing high levels of antioxidants helps in increasing the shelf life so can be used as spray oil for some products such as nuts, crackers and other snacks.

Health Benefits of Rice Bran Oil In terms of fatty acids, rice bran oil has a similar composition to peanut oil. Due to its fatty acid profile and high quantity of unsaponifiable components, it helps in lowering LDL cholesterol. Also, isoprenoid constituents of the oil assist in preventing tumor growth (Kochhar, 2002). Sesame and rice bran oil are better known for their unsaturated FAs and antioxidant properties, thus are assumed in lowering the cardiovascular risks. According to some reports, combination of sesame oil and RBO in 20:80 ratio lowers the blood pressure and cholesterol, and improves lipid profile in mild and moderate hypertensive patients (Devrajan et al., 2016; Pohndorf et al., 2016). RBO is a rich source of some important phytoceuticals such as lecithin, oryzanol, phytosterols, polyphenols and many others. Due to the presence of these phytochemicals, RBO has a unique effect of lowering plasma cholesterol more efficiently (Lai et al., 2019).

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Amandeep Singh, Muskaan Kamboj and Shilpi Ahluwalia Table 1. Characteristics and health benefits of vegetable oils

Oil Coconut oil

Canola oil Sunflower oil Flax seed oil

Sesame oil Soybean oil

Olive oil Palm oil

Peanut oil

Rice bran oil

Characteristics High level of short and medium chain fatty acids, characterized by C6 -C14 length chains Lower amount of saturated fatty acids, neutral flavor Majorly composed of PUFA, linoleic acid High level PUFA, oxidizes easily so not used for cooking

Good amount of proteins and minerals Omega-3 fatty acids, rich in vitamin K and vitamin E, neutral taste High in MUFA, contains bioactive compounds Equal amounts of saturates and unsaturates, richest source of vitamin E and pro-vitamin A, stable during frying Good source of vitamin E, crude oil has nutty flavor

75% unsaturated fatty acids, contains γ-oryzanol, good oxidative stability, pleasant flavor

Health benefits Prevent and treat Alzheimer’s disease (AD) Reduces total cholesterol, Reduces the risk of cardio vascular diseases Defensive against hormone related prostate, breast and colon cancers, reduction in occurrence of cardio-vascular diseases Anti-aging properties, reduce the risk of fatty liver Maintains bone strength, prevents harmful damage of oxygen-free radicals, lowering cholesterol levels and risk of heart diseases Prevents heart diseases, diabetes and cancer Prevents cellular damage, cholesterol reduction ability and anti-cancerous effects Constant reduction in LDL, total cholesterol and TAG levels, lowers cardiovascular disease risk, inhibits cancer growth Lowers cholesterol and cardiovascular risks

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CONCLUSION During the past hundred years, there has been a significant growth in the consumption and production of vegetable oils. Vegetable oils vary in their fatty acid composition and other minor components like sterols, phenols, tocopherols etc. and these nutrients differ substantially depending on the methods implemented during processing and storage. Vegetable oils are a good substitute to saturated fats because of the presence of polyunsaturated fats which makes them “heart-healthy.” Some vegetable oils are beneficial in preventing and curing many diseases, like diabetes, cancer, Alzheimer and coronary heart diseases (summarized in Table 1). Researchers have been working upon the health benefits of vegetable oils produced worldwide, resulting in the fact that these have become an especially important part of our daily diet but the preference of any vegetable oil depends on the functionality of the oil for a particular food application, personal preference, taste and cost. Despite of their composition; either they contain ‘good’ or ‘bad’ fats, they are still 100% fats and therefore should only be included in moderate quantities in our diet.

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Karmakar, B. and Halder, G. 2019. “Progress and future of biodiesel synthesis: Advancements in oil extraction and conversion technologies”, Energy Conversion and Management, 182: 307-339. [3] Vaskova, H. and Buckova, M. 2015. “Thermal degradation of vegetable oils: spectroscopic measurement and analysis”, Procedia Engineering, 100: 630–635. [4] Pantzaris, T. P. and Yusof, B. 2002. “The lauric (coconut and palm kernel) oils” In Vegetable oils in food technology: Composition, Properties and Uses, edited by F. D. Gunstone, 157-159. Blackwell Publishing. [5] Mosconi, L., Alberto, P., Leon, M. J. D. 2009. “Brain glucose hypermetabolism and oxidative stress in preclinical Alzheimer’s disease”, Annals of the New York Academy of Sciences, 1147. 180195. doi: https://dx.doi.org/10.1196%2Fannals.1427.007. [6] Chatterjee, P., Fernando, M., Fernando, B., Dias, C. B., Shah, T., Silva, R., Williams S., Pedrini, S., Hillebrandt, H., Gozee, K., Barin, E., Sohrabi, H. R., Garg, M., Cunnane, S., Martins, R. N. 2020. “Potential of coconut oil and medium chain triglycerides in the prevention and treatment of Alzheimer’s disease”, Mechanism of ageing and development, 186. doi: https://doi.org/10.1016/j. mad.2020.111209. [7] Enig, M. 1999. “The Health Benefits of Coconuts & Coconut Oil”, Coconuts: In Support of Good Health in the 21st Century, Paper presented at the 36th Meeting of Asian Pacific Coconut Community (APCC) meeting held in Pohnpei in the Federated States of Micronesia. [8] Lin, L., Hanja, A., Angela, D., Lisa, C., Shaunda, D. T., Alvin, B., Peter, J. H. J. 2013. “Evidence of health benefits of canola oil”, Nutrition Reviews, 71(6): 370–385. doi:10.1111/nure.12033. [9] Gunstone, F. D. 2002. “Production and trade of vegetable oils”, Vegetable oils in food technology: Composition, Properties and Uses, edited by F. D. Gunstone. 8-9. Blackwell Publishing. [10] Przybylski, R. and Mag, T. 2002. “Canola/rapeseed oil”, Vegetable oils in food technology: Composition, Properties and Uses, edited by

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Amandeep Singh, Muskaan Kamboj and Shilpi Ahluwalia Oils in Food Technology: Composition, Properties and Uses. Edited by Frank D. Gunstone, 18-45. Chuffa, L. G. D. A, Vieira, F. R, da Silva, D. A. F. and Franco, D. M. 2014. “Soybean seed oil: Nutritional composition, healthy benefits and commercial applications”, Seed Oil: Biological Properties, Health Benefits and Commercial Applications, 1-24. Visioli, F., Franco, M., Toledo, E., Luchsinger, J., Willett, W. C., Hu, F. B. and Martinez-Gonzalez, M. A. 2018. “Olive oil and prevention of chronic diseases: Summary of an international conference”, Nutrition, Metabolism and Cardiovascular diseases, 28(7): 649-56. DOI:https://doi.org/10.1016/j.numecd.2018.04.004. Boskou, D., Blekas, G., Tsimidou, M. 2006. “Olive oil composition”, Olive Oil (2nd edition). edited by Dimitrios Boskou., 41-72. DOI: https://doi.org/10.1016/B978-1-893997-88-2.50008-0. Gavahian, M., Khaneghah, A. M., Lorenzo, J. M., Munekata, P. E. S., Collado, M. C., Martinez, A. J. M. 2019. “Health benefits of olive oil and its components: Impacts on gut microbiota antioxidant activities, and prevention of noncommunicable diseases”, Trends in Food Science and Technology, 88: 220-27. DOI: https://doi.org/10.1016/j.tifs.2019.03.008. Foscolou, A., Critselis, E., Panagiotakos, D. 2018. “Olive oil consumption and human health: A narrative review”. Maturitas, 118: 60-66. DOI: https://doi.org/10.1016/j.maturitas.2018.10.013. Daud, Z. A. M., Kaur, D., Khosla, P. 2012. “Health and Nutritional Properties of Palm Oil and Its Components”, In Palm Oil: Production, processing, characterization, and uses. 545-60. DOI: https://doi.org/10.1016/B978-0-9818936-9-3.50021-6. Ogan, I. M., Marie, J. D., Michael, N. 2015. “Palm oil: Processing, characterization and utilization in the food industry – A review”. In Food Bioscience. 10: 26-41. DOI: https://doi.org/10.1016/j.fbio. 2015.01.003.

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[23] Toyin, D. A., Folorunso, A. O., Oluwafemi, O. O. 2020. “Palm oil: its antioxidant potential in diabetes mellitus”. In Diabetes (second edition), 285-91. DOI: https://doi.org/10.1016/B978-0-128157763.00029 2. [24] Catanzaro, R., Zerbinati, N., Solimene, U., Marcellino, M., Mohania, D., Italia, A., Ayala, A., Marotta, F. 2016. “Beneficial effect of refined red palm oil on lipid peroxidation and monocyte tissue factor in HCV-related liver disease: a randomizer controller study”. In Hepatobiliary and Pancreatic Diseases International, 15(2): 165-72. DOI: https://doi.org/10.1016/S1499-3872(16)60072-3. Lin, S. W. 2002. “Palm Oil”. Vegetable Oils in Food Technology: Composition, Properties and Uses. Edited by Frank D. Gunstone, 59-90. [25] Lai, O. M., Jacoby, J. J., Leong, W. F., Lai, W. T. 2019. “Nutritional Studies of Rice Bran Oil”. In Rice Bran and Rice Bran Oil: Chemistry, Processing and Utilization, 19-54. DOI: https://doi.org/ 10.1016/B978-0-12-812828-2.00002-0. Kochhar, S. P. 2002. “Sesame, Rice Bran and Flaxseed Oils”. Vegetable Oils in Food Technology: Composition, Properties and Uses. Edited by Frank D. Gunstone, 297-320. [26] Devarajan, S., Singh, R., Chatterjee, B., Zhang, B., Ali, A. 2016. “A blend of sesame oil and rice bran oil lowers blood pressure and improves the lipid profile in mild-to-moderate hypertensive patients”. In Journal of Clinical Lipidology, 10(2): 339-49. DOI: https://doi.org/10.1016/j.jacl.2015.12.011. Pohndorf, R. S., Cadaval Jr., T. R. S., Pinto, L. A. A. 2016. “Kinetics and thermodynamics adsorption of carotenoids and chlorophylls in rice bran oil bleaching”. In the Journal of Food Engineering, 185: 9-16. DOI: https://doi.org/10.1016/j.jfoodeng.2016.03.028.

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[27] Sanders, T. H. 2003. “Groundnut Oil”, In Encyclopedia of Food sciences and Nutrition (2nd edition), 2967-74. DOI: https://doi.org/10.1016/B0-12-227055-X/01353-5. Rachaputi, R. C. N. and Wright, G. 2015. “Peanuts, Overview”. Reference Module in Food Science. DOI: https://doi.org/10.1016/B978-0-08-1005965.00038-X. [28] Dwivedi, S., Sahravat, K., Upadhyaya, H., Ortiz, R. 2013. “Food, Nutrition and Agro-biodiversity Under Global Climate Change”, In Advances in Agronomy, 120: 1-128. DOI: https://doi.org/10.1016/ B978-0-12-407686-0.00001-4.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 5

VEGETABLE OILS AS AN ALTERNATE SOURCE OF HEAT STORAGE MATERIAL Vishal Dabra Department of Mechanical Engineering, P.I.E.T., Samalkha, Haryana, India

ABSTRACT Energy consumption has been accelerated from the past few decades, which can create an energy crisis in the upcoming years. Researchers have to look for the finest alternative to lessen the energy crisis within the least time. Heat storage materials (HSMs) have become popular in the last two decades to compensate the energy supply. Vegetable oil-based heat storage materials are a gift given by nature and possess the potential to serve in different applications. It also has the ability to substitute the existing toxic and expensive heat storage materials. This study emphasizes on need, types, properties, and the extraction processes of vegetable oils. Also, vegetable oils-based heat storage materials have been elaborated along with their major challenges associated with them. In this chapter, several research scopes are also proposed for future research work. The summary presumes that vegetable oil-based heat storage materials are one of the best heat storage materials for different applications. It works efficiently with renewable energy-based systems

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Vishal Dabra and also helps to recover waste heat from different heat-generating systems.

INTRODUCTION The planetary energy consumption has been increased with modernization and technological advancement. Human beings are trying to overcome the demand of energy based on conventional resources by using various alternative methods and terminologies [1-4]. Thermal energy storage has the potential to supply sufficient quantity of heat to meet the demand. It is one of the best attempts to minimize the consumption of conventional energy resources. It also helps to reduce CO2 emission and reduces the chances of global warming. Nowadays thermal energy storage is drawing the attention of many young researchers. Usually, thermal energy storage methods are divided into three types i.e., sensible, latent, and thermo-chemical heat storage methods [5]. The massive demand of heat energy is fulfilled by adopting latent heat storage method due to the capacity of supplying heat at a constant rate for long durations of the period. HSM has become more popular in a wide range of engineering applications. The process of external heat supply to the system associated with HSM is known as the charging of HSM by storing heat energy. This stored energy is utilized by the system when external heat supply is not adequate for the system and this process is known as discharging of HSM. HSM is categorized into low and high heat storage materials depending upon their latent heat values. Low melting temperature organic materials is very popular due to their easy availability, non-toxic; easy handling, cheaper and non-corrosive nature [6-10]. Fatty acids, esters and alcohols are a few examples of low melting temperature organic materials. The various properties of HSM used in the system are shown in Figure 1 [11-12].

Vegetable Oils as an Alternate Source of Heat Storage Material 103

Figure 1. General properties of HSM.

Thermal Properties Identification of HSM for specific domestic and commercial systems depends upon its excellent thermal properties. Generally, vegetable oils with high latent heat are considered in different systems. It helps to reduce the size of heat storage container. The charging and discharging of HSM is also the function of its thermal conductivity. Highly thermal conductive HSM stores more heat during charging and release it at the time of discharge.

Physical Properties The physical properties of HSM play an important role in designing and selecting the heat storage container. During phase transformation, HSMs with high density are considered due to minimum volume expansion which helps to select the optimum size of the heat storage container and also reduces the containment issues.

Kinetic Properties Super cooling of hydrated salts is one of the most common problems facing during phase transformation. It can be avoided to improve the proper heat withdrawal from a heat storage container.

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Chemical Properties Chemical stability of HSM is required for proper charging and discharging of HSM during phase transformation. The changes in chemical composition make HSM unstable, dehydrated, and incompatible with the system. Along with the chemical stability of HSM, it must be non-toxic, inflammable, and non-explosive from a safety point of view. Out of these basic properties, HSM must possess some special characteristics. It should be available easily in abundance and at a minimum cost. Vegetable oils showing all the discussed properties and characteristics to behave like an HSM in various engineering applications.

EXTRACTION OF VEGETABLE OIL As we know that vegetable oils are extracted from various fruits and seeds. First of all, seeds are collected from plants, trees or herbs and then subjected to pretreatment prior to the extraction of oils from their seeds. After cleaning, the seeds are put on drying at a temperature range of 90115 °C. From dried seeds unwanted substances are picked out manually or by using machines. The kernels are then separated from the hulls. After that clean and dried seeds are crushed or flaked to extract the oil. Different processes are used to extract the oil from crushed and cooked seeds. The most commonly used processes are: 1. 2. 3. 4.

Mechanical process Solvent Process Enzymatic process Carbon dioxide process

Hence, the importance of vegetable oil-based HSMs is elaborated in this study.

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DESCRIPTION OF VEGETABLE OIL BASED HSMS It is a very complex task to choose the cheap and best vegetable oilbased HSM for various engineering applications [13]. Organic nonparaffin HSMs have many characteristic features and perform better in low-temperature range applications (10 to 40 °C i.e., near about ambient temperature). Fatty acids, esters, and alcohols are commonly used organic non-paraffin [14]. Several research studies are available in the literature on vegetable oilbased HSMs. From literature, basic properties, characteristics, applications, and limitations are briefly discussed in this section. The thermal properties of vegetable oils depend on different factors such as purity, temperature, volume, density, and instrument accuracy, etc. The most crucial requirements for HSM are phase transformation temperature and melting enthalpy. So the knowledge about different properties and factors of the vegetable oils are very important before using as HSMs in engineering applications [15]. Vegetable oils consist of triacylglycerols which are also termed as triglycerides. These are simply fatty acids and made up of three acids ester linked to single glycerol. The molecular weight of such compounds is high. The triacylglycerols molecules can crystallize in 3 main crystalline states: A, B, and C. The triacylglycerols are available in solid and liquid form as shown in Figure 2. Generally, these are found in liquid form at atmospheric pressure and temperature. These are also known as plant oil. Vegetable oils are available in ample natural resources and used in different applications [16]. Vegetable oils are non-volatile but unstable at relatively high temperatures. These oils consist of different properties depending upon the constituents and nature of fatty acids. The iodine value indicates that vegetable oils are saturated or not (i.e., grams of iodine absorbed by 100 grams of vegetable oil). It also provides information about the degree of unsaturation present in structure of the vegetable oil. On the basis of the degree of unsaturation, these oils are classified into dry, semi-dry, and nondry oils. According to Wiji method, the value of iodine is determined by using the following formula:

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Vishal Dabra Table 1. Different types of iodine value

Type of oil

Iodine value

Dry oil

> 150

Semi-dry oil

100 to 150

Non-drying oil

< 100

Example 1. 2. 3. 4. 5. 1. 2. 3. 4. 5. 1. 2. 3. 4. 5.

Inseed Perilla Tung Oiticica Walnut Safflower Watermelon Rubber seeds Sunflower Soybean Castor Coconut Ground nut Cotton seed Olive

Table 2. Different properties of vegetable oils Vegetable oil properties High biodegradable Viscosity (at 27 °C) Density Calorific value High flash points Specific heat Lower flammability Fire points Environmental friendly Low toxicity

Value 95% 10.3- 65.4 mm2/s 872-921 kg/m3 37500-39500 kJ//kg (appox.) > 300 °C 1.67 kJ/kgK > 300 °C -

Iodine Value = [12.7 × volume (ml) of thiosulphate required compared to blank × normality of thiosulphate] / mass of oil used in grams. The

Vegetable Oils as an Alternate Source of Heat Storage Material 107 classification of vegetable oil on the basis of iodine value is listed in Table 1. Most of the vegetable oil possesses different properties as highlighted in Table 2 [17-19]. The structure of vegetable oils can be observed in the following manner. 1. 2. 3. 4.

Chain of fatty acids (generally found in C16, C18, C22) Unsaturation is exist in the chain The position of double bond The presence of other reactive functionalities

Figure 2. Solid-liquid transitions in triacylglycerols molecules.

Broadly vegetable oils are classified on the basis of source of oil extraction. Various fruits and seed oils are used as a source of oil extraction. Palm, olive, and avocado oils are commonly used fruit oils. Soybean, rapeseed, sunflower, peanut, cottonseed, palm kernel, flax, hemp, safflower, grape seed oils are commonly used seed oils. The worldwide production of fruits and seed oils in million tons per year is shown in Figure 3.

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Figure 3. Production of fruits and seed oils in million tons per year.

VEGETABLE OIL BASED HSM SYSTEMS Vegetable oil-based HSMs show their dominance in the market due to their different properties and characteristics. Paraffin wax and salt hydrates become, the more popular vegetable oil-based HSM available in the market. Vegetable oil-based compounds are making a strong path and have ability to compete with the available HSMs in the market in terms of availability, cost, easy to handle, and non-toxicity. Approximately three hundred different fat and vegetable oil-based HSMs have been studied by different researchers. Temperature range from minus 90 °C to 150 °C with latent heat of 150 and 220 J/g are observed while working with fat and vegetable oil-based HSMs [20]. Many vegetable oil-based HSMs own very high stability for approximately 30 years. These are considered to be carbon neutral as ranked by the USDA BioPreferred program. The following properties and characteristics must be remembered before selecting the vegetable oils based HSMs:

Vegetable Oils as an Alternate Source of Heat Storage Material 109 1. The range of melting/vaporizing temperature of vegetable oilbased HSM should be within range of working temperature. So that it can absorb heat during charging conditions and release heat during discharging conditions. 2. Vegetable oils with high sensible heat and latent heat of fusion per unit mass are chosen. This helps to minimize the quantity of vegetable oil used and reduce the size of the storage container. 3. Vegetable oils should possess high specific heat, which increases the effect of sensible heat storage. 4. Vegetable oils based HSM of high thermal conductivity are preferred which helps to reduce the duration of charging and discharging. 5. Vegetable oil must possess less value of volumetric expansion and shrinkage coefficients. 6. The condition of sub-cooling must not be encountered while working with vegetable oils based HSM. 7. Vegetable oils based HSM should be chemically stable, which helps to reduce the chances of any hazardous chemical reaction and also not react with storage containers. 8. It must be non-toxic and non-explosive in nature. 9. It should be easily available at lesser cost. 10. It should be easily handled during the operation and replaced when needed. Vegetable oil-based HSMs have the potential to use as an alternate of existing HSMs for specific temperature ranges. Two well-known oils of shea butter and palm kernel are used to evaluate the sustainability of HSM in various heating applications such as maintain heat level in spacecraft heat absorber in electronic devices and heating of water during non-sunshine hours. Solar energy-based systems face fluctuations in heat storage due to variations in solar radiation. To overcome this fluctuation, HSM is used to maintain the constant heat supply of solar-based systems throughout the day. These systems absorb heat during sunshine hours and use this absorb heat at non-sun-shine hours [21]. There are number of oil

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tree species exist in the rain forest of West and East Africa sub-region. Most commonly found oil tree species are Allanblackia species, shea butter, and palm oil. These are medium size trees and average oil production is 12 kg/tree from a net seed weight of 35 kg. Allanblackia oil has a melting temperature range of 42 °C to 44 °C and solid at ambient temperature. Shea butter contains fat near about 41 to 54% and generally produced from nuts of shea butter tree [22-25]. Palm kernel oil is extracted from the oil palm fruit nut. It is present in the pulp of the inner side of the fruit and produced by the crushing of nuts. It crystallizes in the beta form at a temperature range of 0 °C to 25 °C. It is saturated in nature and solid at ambient temperature [26]. Waste palm oil from the food and process industries has properties to replace petrochemical-based organic HSMs. The thermo-gravimetric analysis and iso-conversional methods are used to identify the thermophysical properties of waste palm oil. At 73 kJ/mol of activation energy, kinetic analysis of palm oil is reliable. Hoffmann et al., (2018) [27] suggested that vegetable oils are used as heat-carrying liquid in concentric solar power plants. In this study, seven vegetable oils are taken and compared for different temperature range up to 250 °C. These vegetable oils are rapeseed, soybean, sunflower, palm, copra, cotton, and jatropha. Their properties show variation with increasing temperature. The nature of the working of vegetable oil-based HSM depends on the range of temperature and location of execution. A heat storage unit is attached to a solar-based cooking system and tested at different locations for indoor and night cooking. Vegetable oils are used as a heat storage medium and circulated through a copper pipe in the system. At Juelich (Germany), first heat storage unit based solar cooker is fabricated and assembled. The performance is found satisfactory. India and Mali made some important modifications in this kind of system to make it more convenient. Also, some systems are installed in different parts of Africa and America [28]. To enhance the stability of organic fatty acid ester based HSMs, coconut and palm oils are mixed with exfoliated graphite nanoplatelets [29-30]. Castor oil based HSM is successfully developed for renewable energy storage in the form of heat energy. It is

Vegetable Oils as an Alternate Source of Heat Storage Material 111 prepared by using polymerization. It is stable up to 90 °C and released a temperature range of 54.3 °C and 66.6 °C. The latent heat for melting and freezing is 141.2J/g and 137.1J/g, respectively. It is used as HSM for temperature lower than 180 °C and stable in performance for 1000 thermal cycles. This kind of HSM has the capability to perform better in many applications such as waste heat recovery, solar energy storage etc [31]. For processes of the temperature range of 70 °C to 180 °C, sugar alcohols show their potential to store heat energy and behave like HSM. It has a melting temperature ranging from 77 °C to 167 °C and latent heat values vary from 225 J/g to 340 J/g. Its specific heat at solid form is two to threetime higher liquid forms. It is free from undercooling problems [32]. The temperature range of ambient to moderate, organic HSMs are very likely to use due to their stability of existence. Its melting point is ranging between 30°C to 70 °C and thermally stable for more than 3000 cycles [33].

MAJOR CHALLENGES RELATED TO VEGETABLE OIL BASED HSMS There are several major challenges related to the popularity and usability of vegetable oil [16]. These challenges are listed below: 1. 2. 3. 4. 5. 6.

The challenges associated with vegetable oils are their availability. Thermal conductivity of vegetable oils is poor. It shows no sharp phase transition. It has a low phase change enthalpy. It shows phase segregation. Selection of best method and technology for the extraction of vegetable oils from seeds. 7. Cost of vegetable oil after extraction. 8. It is difficult to handle and store. 9. Market response on vegetable oils based HSM.

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FUTURE SCOPE OF VEGETABLE OIL AS HSMS 1. The purest form of vegetable oils is non-toxic, but it’s too expensive. Therefore, researchers can make blends of various vegetable oils to make it cheaper and uses in various domestic applications. 2. Researchers can develop new methodologies and techniques to extract, vegetable oils from different fruits and seeds. 3. Vegetable oils based HSM are very handy to store vaccines and food products at a critical temperature for a long duration. 4. The thermal conductivity of vegetable oils is low therefore the researchers can take initiative to enhance it. 5. Researchers can work to invent systems for efficient utilization of store energy in a cheaper manner.

SUMMARY This chapter has summarized the potential of vegetable oils to use as HSMs in different engineering applications. It works efficiently with renewable energy-based systems for water heating and drying of food products. It also helps to recover waste heat from different heat-generating systems. Palm oil and sunflower are the most popular vegetable oils used as HSMs due to their low cost and non-toxic nature. Even though less research work has been reported on these materials, but it is anticipated that their research activities will pick up noticeably in the future. The overall summary is that vegetable-based oil is best suited to HSM in various engineering applications and lessens the load on fossil fuels.

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ACKNOWLEDGMENTS I would like to extend my deepest gratitude to Dr. RajitaTuran (Specialist in Plant Biotechnology) for their valuable suggestions and support for this chapter.

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[26] Chong, C. L. W. L. Siew, 1994. “Chemical and physical properties of palm kernel oil.” Proceedings of the World Conference on Lauric Oils: Sources. Processing and Applications 79–83. [27] Hoffmanna, J. F. G. Vaitilingom, J. F. Henry, M. Chirtoc, R. Olives, V. Goetza, X. Py, 2018.“Temperature dependence of thermo physical and rheological properties of seven vegetable oils in view of their use as heat transfer fluids in concentrated solar plants.” Solar Energy Materials and Solar Cells178;129-138. [28] Schwarzerand, K., M. E. V. da Silva, 2003. “Solar cooking system with or without heat storage for families and institutions.” 75; 35-41. [29] Wi S., J. Seo, S. G. Jeong, S. J. Chang, Y. Kang, S. Kim, 2015. “Thermal properties of shapestabilized phase change materials using fatty acid ester and exfoliated graphite nanoplatelets for saving energy in buildings.”Solar Energy Mater. Solar Cells 143; 168–173, [30] Noel, J. A., P. M. Allred, M. A. White, 2015. “Life cycle assessment of two biologically produced phase change materials and their related products.” The International Journal of Life Cycle Assessment 20; 367–376. [31] Wu, B., Y. Zhao, Q. Liu, C. Zhou, X. Zhang, J. Lei, 2019.“Formstable phase change materials based on castor oil and palmitic acid for renewable thermal energy storage.” Journal of Thermal Analysis and Calorimetry. doi.org/10.1007/s10973-019-08041-x. [32] Palomo del Barrio, E., A. Godin, M. Duquesne, J. Daranlot, J. Jolly, W. Alshaer, T. Kouadio, A. Sommier, 2017.“Characterization of different sugar alcohols as phase change materials for thermal energy storage applications.” Solar Energy Materials & Solar Cells 159; 560–569. [33] Kahwaji S., M. B. Johnson, A. C. Kheirabadi, D.Groulx, M. A. White, 2017. “Fatty acids and related phase change materials for reliable thermal energy storage at moderate temperatures.” Solar Energy Materials and Solar Cells 167; 109–120.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 6

USED VEGETABLE OIL: ITS PROPERTIES, CONVERSION TECHNOLOGIES, AND CHALLENGES AS A TRANSPORTATION FUEL Tavayogeshwary Thangadurai and Ching Thian Tye*, PhD School of Chemical Engineering, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang

ABSTRACT Rising demand for energy has spurred the search of alternative resources for renewable and sustainable fuel. Vegetable oil is one of the potential sources of hydrocarbons to be converted into transportation fuel. In order to avoid the competition with fresh edible oils in the food supply, used vegetable oil that is widely available and economical has caught the attention of researchers. There are some issues with the properties of the used vegetable oil which make it impossible to be directly used as a *

Corresponding Author’s E-mail: [email protected].

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Tavayogeshwary Thangadurai and Ching Thian Tye transportation fuel. Those properties, such as viscosity, heating value, oxygen content and cold flow, if not treated, are unfavourable to meet fuel requirements. This chapter discusses the properties of used vegetable oil and the processes involved to modify their properties as required for standard transportation fuel as well as the challenges encountered for the biofuel produced.

Keywords: Renewable, used vegetable oil, properties, transesterification, cracking, pyrolysis

1. INTRODUCTION A rapid hike in global energy consumption of around 53% by 2030 is reported by the International Energy Agency (IEA) [1]. In this light, biofuel is an interesting alternative energy supply that is renewable and sustainable. Over the years, biofuel has been studied for its impact on the economy and environment [2]. In particular, vegetable derived biofuel helps in reducing green house gas emissions since about 78% of CO2 emitted via the combustion of biofuel extracted from vegetables is utilized by the plants themselves in a closed carbon dioxide cycle [2]. Also, compared to petroleum fuel [3], the emission of polycyclic aromatic compounds and unburned hydrocarbons during combustion are reduced by 75–90% and 90%, respectively. In addition, about 75% of the production cost of biofuel is comprised of the price for the feedstock [4]. A key concern of using vegetable oil for fuel is the potential risk of affecting the food supply. This has brought the attention of researchers to used vegetable oil. In general, Asia, Europe and United States generate various types of used vegetable oils in large quantities. These include palm oil, sunflower oil, soybean oil, coconut oil and canola oil [5]. About 15 liters of used vegetable oil is generated per day by each restaurant in Malaysia [6]. There exists several advantages of using used vegetable oil as feedstock for biofuel. Firstly, it does not affect food supply, especially the fresh human consumable oil in this case [7]. Secondly, the cost for biofuel

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production can be reduced 60–90% with used vegetable oil as the feedstock [8]. Thirdly, it is inherently renewable. Though it is biodegradable and nontoxic, recycling or processing of the used vegetable oil is ecofriendly and contributes directly to a better environmental management, as direct disposal of used vegetable oil causes contamination to food chain and pollution to the environment [9]. In many countries, an enormous amount of used vegetable oil is disposed of inappropriately. All of these can be minimized by efficiently utilizing this abundant low-cost resource [10]. However, there are several challenges to be addressed before the used vegetable oil can be utilized as transportation fuel. Note that vegetable oil from various sources consist of fatty acids which differs in carbon chain length, number of unsaturated bonds present (degree of unsaturation) and other chemical compositions. Oil, a hydrophobic substance, consists of triglycerides in which one unit of glycerol is connected to three fatty acids via carboxyl group, for instance, palm oil has a carbon number of mostly C16 and C18 via carboxyl group in triglycerides (Figure 1). In general, vegetable oils contain around 90% to 98% of triglycerides and traces of monoglycerides and diglycerides [11]. The physical and chemical properties of vegetable oil vary with the degree of unsaturation of the hydrocarbons [12] and fatty acids composition in triglycerides. Chain length and degree of double bonds saturation differ for fatty acids [13]. Monosaturated triglycerides contain a double bond between the carbon atoms while polyunsaturated triglycerides have more than one double bond [14]. Vegetable oil with an effective hydrogen to carbon ratio higher than 2 [15] consists of saturated and unsaturated fatty acids with functional groups such as carbonyl, carboxyl and hydroxyl [16]. During cooking and frying, the presence of impurities, high acid value and water content lead to a complex conversion of vegetable oil [17]. Steam is produced during frying hydrolyzes triglycerides to form free fatty acids, glycerol, diglycerides and monoglycerides [9]. The oxidation of used vegetable oil generates hydroperoxides and low molecular weight volatiles, meanwhile polymerization occurs via Diels-Alder and radicals reaction

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[18]. High viscosity, low volatility and poor cold flow properties of used vegetable oil do not satisfy the requirements of current engine fuel [19].

Figure 1. Example of chemical structure of triglycerides in waste cooking oil.

The present chapter provides an overview about the compositions and common properties of used vegetable oil, and its related issues for transportion fuel. It also provides a comprehensive update regarding technologies to convert vegetable oil to fuel as well as challenges to produce transportation fuel from used vegetable oil.

2. COMPOSITIONS OF USED VEGETABLE OIL Vegetable oils derived from different sources have different types of triglycerides with different types of fatty acids. In addition, geographical and climatic variations influence the composition of vegetable oils [20]. In general, vegetable oils contain more unsaturaturated fatty acids than saturated fatty acids. Unsaturated fatty acids refer to fatty acids with double bond(s) such as oleic and linolenic acids whereas saturated fatty acids include palmitic, stearic and myristic acids without double bond(s) in the fatty acids’ back bone [21]. Palm oil, soybean oil, canola oil and linseed oil have double bonds per triglycerides of 1.7, 4.6, 3.9 and 6.6, respectively. Fatty acids in jojoba oil are linked to fatty alcohol and around 97% of monounsaturated hydrocarbons are bonded by ester [22]. The oleic acid content of rapeseed oil, olive oil, canola oil and hazelnut oil are 64.4%, 75%, 53.36% and 77.15%, respectively.

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Sunflower oil, cottonseed oil, corn oil and soybean oil contain more than 50% of linoleic acid. In coconut oil, there are 51% lauric acid, 9.5% caprilic acid and 4.5% of capric acid contained. Basically, used vegetable oils have similar fatty acid contents with their respective source of vegetable oils [27]. Table 1 shows the fatty acid content of various used vegetable oils. Used palm oil was found to have relatively high saturated fatty acid (37%) compared to other used vegetable oils such as rapeseed oil (7.2%), sunflower oil (11-15%) and soybean oil (15%), respectively. Different compositions in the oils have led to slight differences of properties for the various used vegetable oils. One of the most significant differences for vegetable oils compared to petroleum-based transporation oils is the high oxygen content which can be up to 50% in vegetable oils. The difference in compositions has also led to differences in other physicochemical properties, which has made the direct utilization of the used or fresh vegetable oils to transportation fuel infeasible. The oxygen content in vegetable oil was found to be low during deep-frying, in which part of the oxygen content had been stripped off when the temperature of the vegetable oil rose above 120oC during frying. However, the oil that is being heated to 180oC would slowly restore their oxygen content when the oil cools down. Anyhow, repeated use of the vegetable oil for deep-frying resulted in oil with lower oxygen values (10-11wt.%) [3, 28]. Therefore, used vegetable oils are having the properties a step more favourable to being converted to transportation fuel compared to fresh vegetable oil. However, used vegetable oil’s fuel-like property deteriorates with increasing polar compounds generation during frying at high temperatures repeatedly [29].

3. PROPERTIES OF USED VEGETABLE OIL AND RELATED ISSUES AS TRANSPORTION FUEL Used vegetable oil and petroleum derived fuel are both oil that have a distinct nature. Chemically, used vegetable oil can be a source of

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hydrocarbon but at the same time it has a high oxygen content. The high oxygen content of vegetable oil has resulted in different reactions under different conditions. Table 1. Fatty acids content of used vegetable oils Used Percentage of fatty acids composition (wt. %) vegetable Myristic Palmitic Stearic Palmitoleic Oleic Linoleic Linolenic Arachidic Eicosenic oil 14:0* 16:0 18:0 16:1 18:1 18:2 18:3 20:0 20:1 C14H28O2 C16H32O2 C18H36O2 C16H30O2 C18H34O2 C18H32O2 C18H30O2 C20H40O2 C18H34O2 Palm oil 2.34 22.47 12.51 7.56 27.64 14.58 1.55 0 0 [5] Canola oil 0.90 20.40 4.80 4.60 52.90 13.50 0.80 0 0.84 [5] Corn oil 0 10.67 1.47 0 28.49 58.35 0 1.02 0 [23] Olive oil 0 15.30 2.70 1.90 67.10 11.90 0.60 0.30 0 [24] Soybean 0 0 1.85 11.67 25.16 60.60 0.48 0.24 0 oil [25] Sunflower 0 9.49 5.62 0 31.14 53.75 0 0 0 oil [5] * x:y refers to ratio of number of carbon to number of double bond(s).

Table 2. Properties of used vegetable oils Source of used vegetable oil Palm oil Sunflower oil Soybean oil Canola oil

Density, g/cm3 0.91 0.91 0.90 0.87

Viscosity, mm2/s at 40°C 33.50 38.15 51.00 35.30

Acid value, mg KOH/g 30.43 2.63 5.14 2.10

Heating value, kJ/g 39.20 39.30 33.20 39.72

Reference [30] [4] [31–33] [34–36]

This leads to various undesirable properties such as transportation fuel and less satisfactory storage stability. This section discusses some major properties of used vegetable oil and the associated issues related to the conversion of used vegetable oil into an engine fuel. Table 2 shows the properties of some used vegetable oils and Table 3 shows the specification required for biodiesel (B100) used in diesel engines and heating applications. Note that the ranges specified for biodiesel and petroleum

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diesel in European Standard (EN) and American Society for Testing and Materials (ASTM) are similar. This is to make sure the alternative functions well in conventional engines. Table 3. Specification required for biodiesel (B100) [26, 37, 38] Properties Viscosity at 40°C (mm2/s) Water and sediment (vol. %) Flash point (°C) Cetane number Acid number (mg KOH/g) Oxidation stability at 110°C (h) Carbon residue (wt. %) Heating value (MJ/kg)

Biodiesel ASTM D6751 1.9–6.0 93 >47 3 35

EN14214 3.5–5.0 101 >51 6 35

Petroleum diesel ASTM D975 EN590 1.9–4.1 2–4.5 55 >40 >51 >20 >20 35MJ/kg) [26]. Typically, a high caloric value of 39 MJ/kg is found in waste palm cooking oil with long hydrocarbon chains that mainly consist of palmitic acid and oleic acid [48]. Other used

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vegetable oils that are heated to a higher temperature, have a higher heating value than that of the palm oil [7]. Heating of used vegetable oil breaks the double bond that reduces the level of unsaturation, causing a higher heating value [49]. Used vegetable oil with high oxygen content [40] has a low caloric value [45] and high cetane number [50].

3.3. Acid Value As mentioned in the previous section, the heating value of a vegetable oil has a close relationship with the carbon number of its fatty acids. In practice, acid value is used to measure the free fatty acid present in the oil. Used vegetable oil with high moisture content and high acid can cause corrosion [30]. Metal structures are damaged by their reaction with more free fatty acids (0.5–15 wt. %) present in used vegetable oil to form salts at high temperature [10]. The acid value required for fuel specifications of ASTM D6751 and EN 14214 is below 0.5 mg KOH/g [53]. The used vegetable oil is limited for its acid value and content of ester with polar properties that lead to corrosion during storage [54]. Used vegetable oil degrades with increasing polar compounds generation during frying at high temperatures repeatedly [29]. High oxidative stability is expressed with more phenolic compound in the oil [27].

3.4. Cold Flow Properties Low temperature fluidity of fuel is determined by cloud point, pour point and cold filter plugging point which are lower for used vegetable oil. Cloud point refers to the temperature for wax formation whereas pour point is the temperature for the gelling of the fuel [53]. Higher pour point and cold filter plugging point are caused by more saturated hydrocarbons [2]. Cold filter plugging point and cloud point for vegetable oil is in the sequence of castor oil > rapeseed oil > canola oil > soybean oil [20]. A greater tendency for oxidative degradation and good cold flow properties

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are exhibited by the presence of more unsaturated fatty acids with higher double bonds [55]. Long chain saturated fatty acids content in vegetable oil causes poor cold flow properties but good oxidation stability [26]. The thermal stability of vegetable oil is improved with the presence of a hydroxyl group [56]. Hydrocarbon with C20+ solidifies at room temperature [57]. Cold flow properties of the hydrocarbons is affected by its presence of high carboxylic acid [58]. Crystallization at lower temperature is boosted by stronger van der Waals forces between shorter linear carbon chain molecules and double bonds positioned in the middle of the carbon chain reduce cloud point [37]. Therefore, in general, untreated, used vegetable oil causes gum formation, clogging, carbon deposition at the injector orifice, injector fouling and a stricken oil ring in the compression ignition engine [45].

4. TECHNOLOGY TO CONVERT VEGETABLE OIL TO FUEL Sustainable and renewable fuel minimizes dependency on fossil fuel and reduces emission of greenhouse gases [59]. However, ignition delay and brake specific fuel consumption are raised while efficiency, power and the torque of engine is reduced with the use of used vegetable oil as fuel for engines [20]. Hence, the properties of used vegetable oils are adjusted to standard fuel specifications via blending, transesterification, pyrolysis and cracking reactions.

4.1. Blending Used vegetable oil is blended with petroleum-based fuel to modify its density, viscosity, acid value, heating value and oxygen content to meet the specification required for standard engines [4]. 10–40% of used vegetable oil is blended with conventional diesel [60]. According to European standards (EN 590), biodiesel (fatty acid methyl ester, FAME) is allowed to be blended with petro diesel at 7 vol. % [61]. Used vegetable oil can

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also be blended with additives such as n-hexadecanes, hexane, dodecane, acetates and ketones [12]. Petroleum diesel can be blended with green diesel (diesel range hydrocarbons) produced from used vegetable oil as the cetane number enhancer [21]. Used vegetable oil was also mixed with alcoholic solvent and surfactant for microemulsification to alter the viscosity [60]. Higher efficiency of complete fuel combustion is acquired with oxygenates as additives for reduced emission of smoke, carbon monoxide, particulate matters and unburnt hydrocarbons [62].

4.2. Transesterification Triglycerides react with alcohol to form FAME and glycerol in transesterification in the presence of strong base or strong acid as catalyst. Maximum biodiesel yield of 99.38 wt.% was produced via transesterification of used vegetable oil [60]. Homogeneous acid catalyzed transesterification of used vegetable oil resulted in 99% conversion and yield with low energy, more alcohol and time requirement for the reaction [63]. A higher cetane number, lower emission of pollutants without aromatics and sulfur are exhibited by biodiesel [2]. Biodegradable and non-toxic biodiesel reduces exhaust gas emission [62], improves combustion and brake thermal efficiency [64]. A shorter reaction time is achieved for non-catalytic supercritical methanol transesterification which is a simple process that does not require product purification [65]. KOH and NaOH are commonly used as catalysts with good performance whereas methoxide with excellent activity is expensive and hygroscopic. Co-solvents (polar and non-polar) such as tetrahydrofuran and methyl tertiary butyl ether advances the reaction time with a single phase condition. The accelerated reaction time is secured by using supercritical methanol that demands higher temperature (350°C), pressure (45–65 bar) and alcohol [40]. A biocatalysis system is also being tested for transesterification of used vegetable oil. Pseudomonas ntarcti (PS30), Mucor miehei (Lipozyme IM60), Geotrichumcandidum and Candida Antarctica (SP435) are involved in enzyme-catalyzed transesterification.

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This catalysis includes acyl acceptor and lipase (Novozym 435 and R. oryzae) which is a hydrolase enzyme that hydrolyses triglycerides into fatty acid and glycerol [60].

4.3. Pyrolysis Pyrolysis involves severe cracking and rearrangement of hydrocarbon fragments [11]. Pyrolysis is the thermal degradation of triglycerides without oxygen and carbonaceous material [48]. Diesel range linear C12 – C17 alkanes or olefins [58] produced in pyrolytic process of used vegetable oil have a higher cetane number that is compatible with current infrastructure and engines [66]. Used vegetable oil underwent decomposition at a high temperature of 400°C to generate hydrocarbons, but selectivity towards C20+ hydrocarbons and oxygenated compounds rise at a lower reaction temperature [30]. Pyrolysis of used cooking palm oil using a microwave-heated bed of activated carbon generated 70 wt.% of bio-oil yield with 65% of diesel range (C10 – C15) hydrocarbons with 46 MJ/kg calorific value. The bio-oil produced contains hydrocarbons such as alkanes, alkenes, cycloalkanes, carboxylic acids, ketones and aldehydes with 5 wt.% oxygen content, about 1 wt.% of nitrogen content and sulfur. The presence of sulfur in the biofuel leads to SOx emission during combustion in engine whereas carboxylic acids form acidic tar or sludge via polymerization [48].

4.4. Catalytic Cracking Catalytic cracking is advantageous for the generation of hydrocarbons in the boiling point ranges of gasoline, jet fuel, kerosene and diesel fractions [52] with low processing cost and higher feedstock flexibility [5]. Liquid product from zeolite catalytic cracking of used cooking oil was reported highly selective toward aromatic and long aliphatic compounds [67]. The presence of aromatics in the fuel contributes to a higher octane

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number despite it being restrained for environmental regulations. A high octane number prevents knocking for a higher calorific value that releases high heating energy during combustion of the fuel [7]. Use of catalysts lowers the activation energy required for the cracking reaction [68]. Less coke formation is attained with basic metal than acidic metals as catalysts but it has an undesirable cracking activity with lower deoxygenation which produced more light-fraction hydrocarbons [6]. The selection and stability of catalysts are important for the exothermic reaction [69]. The properties of cracking oil such as density, viscosity and calorific value were in the range specified for petroleum-based fuel [58].

Figure 2. Reaction mechanism for catalytic cracking of triglyceride in used vegetable oil.

Green fuel, which is produced from catalytic cracking has a higher cetane number of 70–90 [70] and clean burning with 70–90% less greenhouse gases (GHG) emission, lower naphthenes, sulphur and oxygen content [6]. Lower density and viscosity of liquid product of catalytic cracking of used vegetable oil are caused by weaker chemical interaction between the molecules of shorter chain hydrocarbons with lower oxygen content [44]. Figure 2 shows the reaction mechanism of the catalytic cracking of used vegetable oil. During catalytic cracking reaction, triglycerides are cracked or hydrolyzed into fatty acids. Decarboxylation or decarbonylation of carboxyl or carbonyl group of, for instance, C16 and C18

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fatty acid derivatives produce C15 and C17 hydrocarbons with the loss of one carbon for deoxygenation as CO2 and CO removal. C21 – C24 heavy oxygenated intermediates are produced via the cracking of triglycerides, ketonization, aldol condensation and cyclization [6]. Efficient deoxygenation spotted at high pressure built for activation of catalyst reaction sites. Decarboxylation of fatty acids in used vegetable oil via C – O cleavage was reported improved by 1–5 wt.% water content whereas cracking of C – C bond was enhanced by more free fatty acid content (>23%) [71].

4.5. Hydrocracking Catalytic cracking under high hydrogen pressure (~10 bar) and orhydrocracking of used vegetable oil increases the gasoline and light gas oil produced [72]. High conversion and selectivity towards alkanes (C12 – C22) with better cold flow properties than that of FAME are yielded via hydrodeoxygenation reaction which is compatible to current infrastructures and engines [17]. Cracking and isomerization during hydrocracking produce shorter branched hydrocarbons with high combustion heat and a low freezing point [73]. Hydrogen source reduces formation of carbonaceous substance on catalyst and removes nitrogen, sulfur and oxygen content in feed [70]. Nonetheless, the high consumption of hydrogen at high pressure for hydrotreating reaction is unfavourable [4]. Much preferred, is a hydrocracking process with deoxygenation and cracking reactions with least cyclization and aromatization to produce diesel range hydrocarbons. There was a report on the deoxygenation and hydrogenation of used vegetable oil blended with a solvent occurring at a temperature of 275–325°C whereas C-C/C-H cracking, cyclization and aromatization dominates at 325–375°C [74]. Hydroprocessing cracks triglycerides to produce (C9 – C16) jet fuel range alkanes with deoxygenation for higher cetane numbers, good cold flow properties and flash points. For used palm cooking oil, mostly C15 – C18 alkanes were produced where hydrodeoxygenation of free fatty acids

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generates C16 and C18 hydrocarbons while decarboxylation or decarbonylation formed C15 and C17 hydrocarbons with oxygen removal as H2O, CO2 and CO. Heavy oxygenated waxy intermediates generated via ketonization and aldol condensation causes catalyst deactivation [59]. Used vegetable oil can also be upgraded via co-processing with middle distillates of petroleum refineries [75]. Conversion, diesel selectivity and saturation of hydrocarbons were enhanced by co-processing of heavy atmospheric gas oil with used vegetable oil [76]. Co-processing of more used vegetable oil with heavy gas oil reduced pour point of product [77]. Neste NExBTL and UOP/Eni EcofiningTM technologies produce green diesel from vegetable oil via co-processing with gas oil [78]. Hydrotreated vegetable oil provides a better dispersion with air homogeneously which reduces ignition delay in combustion chamber [54]. However, the process produced straight hydrocarbons with higher cloud point, pour point and cold filter plugging point of 20–30°C [52].

5. CHALLENGES TO PRODUCE TRANSPORTATION FUEL FROM USED VEGETABLE OIL Although processing of used vegetable oil improves their properties, there are some challenges encountered due to the properties of the feedstock, operating reaction variables and characteristic of products relative to the specifications for standard transportation fuel.

5.1. Feedstock The transesterifcation of used vegetable oil is influenced by its free fatty acid and moisture content (0.05–7%) [79]. Used vegetable oil with higher free fatty acids (>2 wt. %) neutralizes base catalyst in transesterification to form soap via saponification which requires

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degumming process [7]. Water content in used vegetable oil hydrolyzes the triglycerides to form free fatty acids [39] and high moisture content favours saponification over transesterification with reduced FAME yield [9]. Change of feedstock alters the composition of fatty acid methyl ester produced [39]. The chemical properties of used vegetable oil varies as its compositions differ with their sources [5]. Impurities in the used vegetable oil such as food seasonings (NaCl) decelerates the hydrodeoxygenation reaction [17]. This causes catalyst deactivation and poisoning [80]. During frying and repetitive heating, some free fatty acids form toxic polar compounds, which are undesirable [9].

5.2. Reaction Related Issues Acids (such as HCl and H2SO4) and enzymes which are insensitive to free fatty acids are suitable to catalyze the transesterification of used vegetable oil with relatively high free fatty acid content compare to vegetable oil. However, they are costly catalysts and require longer reaction time and more alcohol during reactions compare to base (NaOH and KOH) in catalyzing transesterification. Solid acid catalysts for transesterification reaction have complex synthesis and active phase leaching that contaminates product [39]. On the other hand, homogeneous catalysts with higher activity complicates product separation [81]. The slower reaction rate, complication for product separation, requirement of more methanol, environmental and corrosion problems are the issues encountered for homogeneous acid catalysts [82]. Besides, carbonaceous compound is generated through polymerization of acrolein produced via reaction of glycerol with oxygen at high temperature deposits at injector nozzle, pistons and valves [83]. Toxic waste produced in transesterification contaminates glycerol and complicates the separation process which requires washing and purification that adds to the cost. On the other hand, the enzymatic transesterification is sensitive towards the temperature and pH of the reaction [84].

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Noble metals (Pd, Pt, Rh and Ru) which are expensive and acidic zeolites (ZSM-5, MCM-41 and SBA-15) with complicated preparation procedure have better catalytic activity in cracking reactions. However, catalyst deactivation is a major issue. Deactivation of acid catalysts is caused by coke formation that covers the reactive sites [6]. Polymerization and condensation of hydrocarbons in used vegetable oil cause catalyst deactivation due to coke deposition [70]. Metal catalysts experience sinthering of the active phase that leads to deterioration of their performance and product contamination [85]. Hydrodesulfurization of the CoMo catalyst was limited by the same active sites competing for deoxygenation reaction [76]. Sulfur leaching, caused by sulfonated acid catalyst in cracking reaction, contaminates the product. Further, the rapid exothermic cracking of used vegetable oil in micro-batch closed system released toxic emissions such as H2S and SOxvia hydrogenation, oxidation, alkylation and polymerization [71].

5.3. Product Biodiesel (FAME) produced via transesterification of used vegetable oil has issues such as high viscosity and poor cold flow properties [13]. Transesterification produces FAME with low heat content and high oxygen content (11%) leading to poor storage stability [71]. Biodiesel, which has high cloud point and pour point than the petroleum diesel [37], has poor cold flow properties [86]. The large molecular mass of FAME and its chemical structure lead to higher viscosity of the biodiesel [37], which causes poor atomization of fuel and carbon deposition [37]. It also has storage stability issues, deposit formation, gelling, gumming, crystallization, filter clogging at lower temperature and NOx emissions [7]. Soap generated during transesterification deactivates catalysts and reduces FAME yield with complication for purification and glycerol separation. Semi-solid mass formation is caused by gel-up of saturated fatty acid soap solidification [39].

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CONCLUSION Used vegetable oil, is a low-cost waste, in abundance, with hydrocarbons similar to fuel fraction, is a potential substitute for petroleum fuel. Despite some of its economical and environmental benefits, it is not directly usable for current transportation vehicles due to its higher viscosity, acid value and poor cold flow properties. Thus, used vegetable oil undergoes transesterification to produce FAME (biodiesel) where the catalytic cracking or hydrocracking of used vegetable oil yields green fuel (specific fuel range hydrocarbon derived from vegetables/plants). However, there are still challenges to be overcome especially for the biodiesel production through transesterification. The presence of high oxygen in biodiesel (FAME) affects its cold flow properties and can be improved with further deoxygenation via catalytic cracking or hydrocracking to produce hydrocarbon of a better quality or green fuel. Used vegetable oil with high free fatty acids [53] is favoured by deoxygenation via cracking reaction. For cracking processes, product yield and selectivity are major issues. Despite of all these issues and challenges for converting used vegetable oil to be transportation fuel, it is still considered one of the most attractive alternative feedstocks for transportation fuel.

ACKNOWLEDGMENTS The authors acknowledge financial support from the Ministry of Higher Education Malaysia under FRGS grant (A/C: 203.PJKIMIA.6071445).

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[74] Wang, H., Zhang, L., Li, G., Rogers, K., Lin, H., Seers, P., Ledan, T., Ng, S. and Zheng, Y. (2017). Application of uniform design experimental method in waste cooking oil (WCO) cohydroprocessing parameter optimization and reaction route investigation. Fuel. 210 (June): 390–397. [75] Tsita, K. G., Kiartzis, S. J., Ntavos, N. K., and Pilavachi, P. A. (2020). Next generation biofuels derived from thermal and chemical conversion of the Greek transport sector. Thermal Science and Engineering Progress. 17: 100387. [76] Bezergianni, S., Dimitriadis, A., and Meletidis, G. (2014). Effectiveness of CoMo and NiMo catalysts on co-hydroprocessing of heavy atmospheric gas oil-waste cooking oil mixtures. Fuel. 125 129–136. [77] Bezergianni, S. and Dimitriadis, A. (2013). Temperature effect on cohydroprocessing of heavy gas oil-waste cooking oil mixtures for hybrid diesel production. in: Fuel, 579–584. [78] Ameen, M., Azizan, M. T., Yusup, S., Ramli, A., and Yasir, M. (2017). Catalytic hydrodeoxygenation of triglycerides: An approach to clean diesel fuel production. Renewable and Sustainable Energy Reviews. 80 1072–1088. [79] Guo, J., Sun, S., and Liu, J. (2020). Conversion of waste frying palm oil into biodiesel using free lipase A from Candida antarctica as a novel catalyst. Fuel. 267 (January): 117323. [80] Chiaramonti, D., Buffi, M., Rizzo, A. M., Lotti, G., and Prussi, M. (2016). Bio-hydrocarbons through catalytic pyrolysis of used cooking oils and fatty acids for sustainable jet and road fuel production. Biomass and Bioenergy. 95: 424–435. [81] Alaei, S., Haghighi, M., Rahmanivahid, B., Shokrani, R., and Naghavi, H. (2020). Conventional vs. hybrid methods for dispersion of MgO over magnetic Mg–Fe mixed oxides nanocatalyst in biofuel production from vegetable oil. Renewable Energy. 154 1188–1203. [82] Jacobson, K., Gopinath, R., Meher, L. C., and Dalai, A. K. (2008). Solid acid catalyzed biodiesel production from waste cooking oil. Applied Catalysis B: Environmental. 85 (1–2): 86–91.

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[83] Estevez, R., Aguado-Deblas, L., Bautista, F. M., Luna, D., Luna, C., Calero, J., Posadillo, Aand Romero, A. A. (2019). Biodiesel at the crossroads: A critical review. Catalysts. 9 (12). [84] Touqeer, T., Mumtaz, M. W., Mukhtar, H., Irfan, A., Akram, S., Shabbir, A., Rashid, U., Nehdi, I. A. and Choong, T. S. Y.(2020). Fe3O4-PDA-lipase as surface functionalized nano biocatalyst for the production of biodiesel using waste cooking oil as feedstock: Characterization and process optimization. Energies. 13 (1). [85] Ameen, M., Azizan, M. T., Ramli, A., Yusup, S., and Abdullah, B. (2019). The effect of metal loading over Ni/γ-Al2O3 and Mo/γAl2O3 catalysts on reaction routes of hydrodeoxygenation of rubber seed oil for green diesel production. Catalysis Today. [86] Chen, S., Zhou, G., and Miao, C. (2019). Green and renewable biodiesel produce from oil hydrodeoxygenation: Strategies for catalyst development and mechanism. Renewable and Sustainable Energy Reviews. 101 (July 2018): 568–589.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 7

BIOFUEL AND FUEL CHARACTERIZATION FOR IC ENGINES P. S. Ranjit1, Venkateswarlu Chintala2, A. Veeresh Babu3 and Yashvir Singh4 1

Department of Mechanical Engineering, Aditya Engineering College (A), Surampalem, Andhra Pradesh, India 2 School of Engineering and Applied Sciences, National Rail and Transportation Institute, Vadodara, Gujarat, India 3 Mechanical Engineering Department, NIT Warangal, Telangana, India 4 Deprtment of Mechanical Engineering, Graphic Era, Dehradun, Uttarakhand, India

ABSTRACT Various low emission situations have exhibited that the objectives of the Kyoto Protocol cannot be accomplished without giving an enormous job to biofuels by 2050 in the worldwide energy economy (Vertès, Inui et al. 2006). Among the reasons why biofuels are suitable for such progress, one may recognize: (i) their straightforwardness; (ii) their creation through notable agrarian innovations; (iii) their potential for alleviation of atmosphere warming without complete rebuilding of the current working

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P. S. Ranjit, Venkateswarlu Chintala, A. Veeresh Babu et al. energy framework; (iv) the utilization of existing engines for their transportation (in any event, considering the customary turbofan utilized in avionics) (Kleiner 2007, Rothengatter 2010); (v) their capability to encourage the overall activation around a typical arrangement of guidelines; (vi) their potential as a legitimately accessible energy source with great open acknowledgement; (vii) their more uniform dispersion than the appropriations of petroleum derivative and atomic assets; and (viii) their capability to make benefits in country zones, including business creation.

Keywords: biofuel, fuel characterization, Generations of Biofuel,

INTRODUCTION Inexhaustible fills are increasing more significance as a substitution to non-sustainable oil-based energizes. The significant explanations behind the improvement of different sustainable assets for fuel creation are to accomplish the security of energy required for transportation, to deliver naturally kind powers, to use in the engines previously produced for different sorts of vehicles, lessen wellbeing perils and to give the client a preferred financial position. Biodiesel is one of the most significant sustainable energizes that falls into this class do not require any modification of the current engines and display huge preferences over oil inferred diesel fuel (Jayed, Masjuki et al. 2009).

BIOFUEL Importance of Biofuels In internal combustion engines, there are several reasons why biofuels should be used. Some key reasons are:

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Good gasoline efficiency than crude oil Reduced sulfur and aromatic pollution and intensity from the engine Property that is biodegradable Fuel neutral to carbon Oxygenated fuel Species habitat expansion Expansion of the food web Helps ensure a healthy balance of feeding plant productivity raise (soil quality) Lack of surface erosion; Improvement of water quality by species of algae

Biofuel Asset Capability Recently, resilience has been demonstrated in agricultural plants when the Light influences herbivores and carnivores. The plants develop in the biosphere, which exists both in the earth based environment and in the marine environment. In four significant circles the earth can be separated: lithosphere, hydrosphere, climate and biosphere. In the biosphere, most animals live and rely on each other, in the majority of the forms. A bioplant gains energy from the sun by turning into glucose through photosynthesis via carbon dioxide and water under daylight. Therefore, the plant requires a specific portion of energy and lives through the resilience of its twigs, seeds and leaves. At this point, by defecation and radiation, the plant removes part of the new energy. A feedstock for biofuel processing or bioenergy is the sparing energy on the plant base—a chart showing biofuels supplied from the feedstock of the first, second, also third generations. The biomass generated in earthly frames by third-generation biofuel from biomass feeds provided in aquatic systems is referred to as the biomass used in the first and second-generation biofuels.

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Figure 1. Biofuels.

Figure 1 shows the maintainability of biofuels as far as feedstock production is concerned, and the food framework does not dispute. It often ends from the focuses as mentioned earlier that biofuels cannot give a viable turn to events of energy if they are not supplied from the correct

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feedstock. It can also give negative results if it runs counter to food production. A plant's leaves and stems are solid substances containing atomic carbon, hydrogen, nitrogen and inorganic structures. The bioenergy is known and can be used as heating fuel. The plant seeds produce oil, hydrogen and volatile substances. The seed variance can be isolated and fuel consistency improved later

Biofuels: First Generation, Second Generation, and Third Generation The biomass is the source of sugar, lipid, and starch separated from the plant for the original biofuels. Sugarcane molasses, for example, are the feeder for ethanol production. In both situations, ethanol will also be supplied from the sugar feedstock; however, it may interfere with the supply of fuel. Soybean oil is used in many countries as a consumable oil but can also be used as a biodiesel supplement. As original biofuels could controvert the source of food, these are not fair competences. Second-generation biofuels are gotten from cellulose, hemicellulose, and lignin in squander feedstock or as a result. These feedstocks incorporate ranger service squanders and agro residue, which can develop in debased land. Amphibian plants are the origins of biofuels from the third generation. Because 66% of our planet is flooded in oceans, this feedstock has tremendous potential for the production of biofuels. Green growth is one example of this type of feedstock.

Effect of Bioenergy on Ecosystems Biology is the investigation of co-operations among life forms and creatures and their condition. A biological framework is a progressively

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settled zone where all living beings associate with the earth (air), hydrosphere (water) and lithosphere (land and soil)). An environment management a specific organic network and its collaboration with abiotic parts. Instances of biological systems incorporate waterway environments and marine biological systems. Environments can be characterized comprehensively into two classifications: earthbound biological systems and amphibian biological systems. A waterway biological system incorporates its biotic segments (all the flying creatures, fish, bugs, green growth, and microscopic organisms living in that waterway), just as abiotic segments (the stones, sand, soil, and water in that stream). Natural procedures include the metabolic elements of biological systems: energy stream, essential cycling, and the creation, utilization, and deterioration of natural issue. An environment likewise incorporates the accompanying:         

Food Web Source of energy/oil Biomass of cells (wood) Reuse of nutrients Live O2 delivery Enhance soil maturity Disintegration reduction in the soil CO2 relief

Effect of Bioenergy on the Environment The effect of bioenergy on the earth includes the sequestration of CO2, low vehicle emissions (because of inside the fuel structure, no Sulphur, and aromatics) by the photosynthesis procedure. Carbon dioxide is typically spread throughout the environment through manufacturers (e.g., trees). On

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the off chance that the maker thickness builds, the CO2 in the environment will diminish moderately. Plants create oxygen during the photosynthesis process. On the off chance that the CO2 in the climate diminishes, the dissolving of CO2 in seawater will likewise diminish, bringing about a constructive outcome on marine species. Noticed that the pH estimation of water diminishes with expanding CO2 fixation in seas. Bioenergy analysis of certain forms of green energy In the environment, there is no pollution of the natural power supply, including sunlight and wind. Nevertheless, these systems cannot sequestrate CO2 pollution in the environments and cannot generate O2 also. For these functional resilience systems, the biological system limits will not alter. Bioenergy and biofuels, among the sustainable energy supply frameworks, have an alternative component to maintain the earth's environment, although the other sustainable energy sources have no impact on earth biology.

Biofuel: Neutral Carbon Fuel Unbiased fuel is known as biofuel. Carbon is the carbon dioxide used during the photosynthesis process in a plant. If the plant ingests owing to a timberland burn or fuelwood fire, the carbon discharged into the atmosphere is then discharged. Thus the carbon releases into the plant once more an equivalent measure of carbon into the climate at the end of the cycle of vegetation. In the plant and climate, carbon is therefore adjusted, called carbon without prejudice because carbon/carbon dioxide is no longer expanded into the air again. As shown in the following equation, biofuels that once again assimilate and discharge carbon into the climates will be called nonparty carbon powers. Carbon dioxide emitted from a warm engine loaded with biofuels does therefore not contribute to rising environmental outflows. Kp - Kr = 0

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where Kp = Carbon put away in the plant Kr = Carbon discharged into the environment

FUEL QUALITY CHARACTERIZATION FOR IC ENGINES Introduction In improving the exhibition and discharging of an internal combustion engine, the double staves of fuel quality and engine innovation take on a key role. Occasionally, the upgrade of fuel quality occurs worldwide to meet stringent emission criteria and high fuel economy, which helps the buyer. Four techniques would practically illustrate the elective fuel or defined fuel:    

Study on the fuel efficiency; Exploratory check of the seat on the central ignition motor; Dynamometer Skeleton focuses on a car; Preliminary field investigation of a car.

The enhancement of fuel efficiency and engine invention involves certain four measures to conform with strict emission requirements as well as the determination of the ability of another or elective petrol.

Fuel Quality Study SI Engine: Octane, strength, weight, olephine are the primary fuel content guidelines required for these fills or in an strength should be met with elective fluid

purity, carbon, fragrance and specifications. The particular examination with essential gas power (e.g., ethanol, methanol

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and butanol, and vapour energies), for example, Liquified Petroleum Gas (LPG), compact gas oil, biogas, manufacturers gas and hydrogen. CI Engine: The specific fuel quality specifications involve cetane number, viscosity, purity, sulfur and aromatic properties. The perfect requirements will be followed by the elective fillings including biodiesel, F–T diesel petrol, dimethyl ether and di-ethyl ether. If any of the fuel features do not reach the ideal level, the display and the internal ignition engine exhaust characteristics will decrease. In processing plants, the quality of the fuel is revised with reasonable consideration. For starters, the benefit of expelling diesel aromatics will be to decrease the flow of polyaromatic hydrocarbon (PAH). Again, fuel costs would be high and economically unsustainable. Vehicle developments could decrease the PAH by enhancing volumetric efficiency, for instance, common rail direct injection (CRDI). This could lead to sustainable oiland transport sector development through a mixture of fuel quality improvement and engine innovation. A more splendid meeting between the original manufacturer of equipment (OEM) and oil organizations would be required to boost the standard of gasoline. Basic Physico & Chemical aspects: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Heating Value Flash Point Fire Point Cloud Point Pour Point Viscosity Octane Number Cetane Number Ash content Carbon Residue Bulk Modulus

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Heating Value The calculation of the heating intensity of fuel is otherwise regarded as the burning heat and is transmitted as kJ/kilogram. In a steady amount of fluid or fuel that only contains carbon, hydrogen, oxygen, nitrogen or sulfur, the amount of ignition is the quantity of temperature which is released by the mass of units of the fluid in a closed area with a uniform size, vaporous, carbon dioxide, oxygen, sulfur dioxide and liquid water at the base temperature benefit from the burning phase. The burning heat is part of the energy that fuel can achieve. Information on this value is essential because of the heat productivity of equipment to produce force. In oxygen-bomb calorimeter under controlled conditions, the heat of the inflammation is dictated by a sampled test. The temperature change is measured by an instrument for the temperature loss that enables the exactness of the research technique to be obtained. Temperature perceptions before, during and after combustion are used to determine the heat of burning, with appropriate rewards for thermal and heat-move fixes. It may be possible to use either iso peribol or adiabatic calorimeters.

Figure 2. Schematic representation of Bomb Calorimeter.

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The method for calculating a heating value for fuel is to calculate, by semi-micro-logical parity, the example cup to 0.01 mg. Find a touching tape with a little weight over the height of the cup, stir firmly around the edge with a single cutter. Find a portion of 4 to 13 mm in the centre of the cassette, and fix a single edge to the centre of the cassette to make it work. Carefully weigh the cup and label. Expel with forceps from the balance. Complete the example with a hypodermic syringe. The test volume important for increasing the temperature is about 35 kJ. The tip of the nail in the tape loop should be attached to the cup through embeddings, such that the attachment of the cup protects the needle's limitless availability. The fold is compressed in the area using a material spatula. The bowl is measured and checked once more. The entire activity of measurement and completion is taken to prevent the uncovered fingers from reaching the cup or tape. The cup is put in the bent terminal, and the wire circuit is designed to drive the middle section down on the central generation. Through successfully removing it, the explosive is removed. To evacuate the air caught, the bomb is not cleaned. The bomb is removed from the oxygen chamber and the spread of the valve is removed. The attacker could not be fooled closely. If the oxygen in the bomb exceeds 4.0 MPa is not released, the ignition should not be started. The stirrer engine switches on the calorimeter, and it is switched off. The control switch is used in close competition with the container temperature to acquire the coating temperature manually. The controller can naturally control the temperature and harmony after 15 minutes. Now and in addition to the endpoint, the coating temperature is controlled to the same or marginal temperature (probably 0.005°C) below. Readings are taken 1 minute before there are no adjustments between three readings back to back. The explanation finishes with the capture of the beginning unit distressed. The illumination of the pilot shines bright, and the temperature continues to rise in 15 s. (The test needs to be stopped in the case that the temperature will not continue to rise). The underlying resistance is interpreted and registered. Temperature readings are performed at a rate of 1 minute after 6 minutes from termination. The three

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reverse readings need not shift, or the readings will decrease. Next time, the last temperature is recorded and evaluated by the 0.0005 ° C incentive. The sensor is disabled, and the stirrer is removed from the calorimeter. It is possible to release the needle valve at a uniform rate so that the stress to barometric weight can be reduced in at least 1 minute. The explosive is removed, and the interior is tested for unbranded fuel. In the absence of a carbon warning, the check should be dismissed. The pump bombs are purified with a thin stream of water and the washings, including cathode and sampling cup, stored in a 500 cm3 container. Essential measurement of water is used, ideally less than 300 cm3. The washing facilities are titrated utilizing an in-house salty methyl root marker. The example sulfur ingredient of this example is resolved to a minimum as defined by ASTM test method D129, D1266-IP 107, D2622, D3120, D4294, or D5453.

Cloud and Pour Point The cloud point is a dynamic indication where the least noticeable bunch of hydrocarbon (HC) initially exist under endorsed conditions after the cooling is finished. The cloud point technique is focused on the detection of the proximity of wax charms in the example; besides, inorganic mixtures and water steps could also be taken. The cloud strategy aims to move fluids into a two-step system consisting simultaneously of solid and fluid from one fluid phase. The example is pre-defined and occasionally analyzed. At the base of the test container, the cloud temperature is reported first as the cloud level. Wax charms appears like a white or smooth bear fixture, and the test method is then referred to as. If the example temperature is small enough to form useful pillars of wax, the cloud emerges. The test example is established in the approved conditions at the lowest temperature. An oil example aims to track its temperature of use for particular purposes. Contraction for cloud and pour estimation, consisting of a glass test container in tube form with an outer diameter of 33–35 mm and a height of 110 mm and 130 mm. Within the width of the container, the thickness of

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the divider should not be more prominent than 1.6 mm but can be between 30 and 33 mm. The container will be divided into a line to show the sample stature inside the base 55 ± 2 mm. The test container shall be inserted into the metal or glass cover with an inner length of 45–46 mm and is waterresistant, circular and stable, level foundation, roughly 115 mm upward to bottom. In a vertical situation in the cooling shower, it is supported free from excessive vibration so not to exceed 27 mm of the refrigeration medium. In the mechanical assembly, thermometers should be mounted.

Cloud Point The cloud procedure is the example to be tested and, at any rate, 14°C over a regular cloud point is brought to temperatures. All possible humidity can be evacuated via the dry lintel channel paper by a technique, but this filtration is made over a rough cloud level at any temperature of 14°C. The test container is completed in the example level. A plug that transports the test thermometer is shut off the test container when the cloud level is above −36°C, broad cloud and thermometers for the atmosphere are used because the atmosphere value is smaller than −36°C, and the minimal cloud value is used for the thermometer. The relation suits well, the thermometers and containers are coaxial, and the thermometer is placed on a base of the containers following the requirements of the stopper and the thermometer. Make sure that the seal, the joints are held close and dry inside the cloth. The circle is mounted at the coat's middle. The circle and coat have been inserted at least 10 minutes before the test box is embedded in the cooling mechanism. During vacant coat cooling, the coat spread may be used. The gasket is placed 25 mm from the base around the test container. The test container is integrated into the coat. The container should not be put in the cooling medium directly. The cooling shower temperature is kept at 0 ± 2°C. The jar is easily extracted from the coat at a 1°C check thermometer without disrupting the example; after a cloud review, it is replaced in the coat. This total activity does not take more than 3 s. When the oil has not

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been chilled at 9°C, the container must be transferred to a coat during the following shower, maintained at −186 ± 1.5°C. The oil must be removed from the test container. The robe should not be shifted when the cloud is cooled at −6°C, the test container shall move to the coat in the third shower at a temperature of −336 ± 1.5°C, in case the example does not show a cloud. The container is transferred to the next shower of each case if the example does not display the cloud point, and the example temperature is as small as the one known in the present shower. Extra showers are required to guarantee low cloud focus. The cloud point at 1°C closest, where any cloud is seen at the bottom of the test container and checked by continued cooling, is taken into account.

Figure 3. Cloud Point Apparatus (Apparatus).

Pour Point The measurement jar is loaded up to the standard limit. If so, the sample should be pumped into a shower before it is only enough liquid for the intent that the test jar will be very well full. Tests of residual strength, dark oils and retardation stock, which during the previous 24 hours is

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warmed to a temperature greater than 45°C, or when their warm past is uncertain, are held at room temperature for the first 24 hours before being tested. Tests known to not be sensitive to warm history by the administrator must never be kept 24 hours before testing at room temperature. With the connection that transmits the thermometer, the measurement jar is locked. Because a higher thermometer, like IP 63C and ASTM 61C, is used for focusing over 36°C.

REFERENCES “Bomb Calorimeter.” from http://www.chem.hope.edu. “Saybolt Viscometer.” from https://instrumentationtools.com. Hamadi, A. P. D. A. S. Properties of Petroleum Products Part (1), University of Technology, Chemical Engineering Department. Jayed, M., H. H. Masjuki, R. Saidur, M. Kalam and M. I. Jahirul (2009). “Environmental aspects and challenges of oilseed produced biodiesel in Southeast Asia.” Renewable and Sustainable Energy Reviews 13(9): 2452-2462. Kleiner, K. (2007). “Civil aviation faces a green challenge.” Nature 448(7150): 120-121. Rothengatter, W. (2010). “Climate change and the contribution of transport: Basic facts and the role of aviation.” Transportation Research Part D: Transport and Environment 15(1): 5-13. Vertès, A. A., M. Inui and H. Yukawa (2006). “Implementing biofuels on a global scale.” Nature Biotechnology 24(7): 761-764.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 8

JATROPHA CURCAS P. S. Ranjit1,*, Venkateswarlu Chintala2, A. Veeresh Babu3 and Yashvir Singh4 1

Department of Mechanical Engineering, Aditya Engineering College (A), Surampalem, Andhra Pradesh, India 2 School of Engineering and Applied Sciences, National Rail and Transportation Institute, Vadodara, Gujarat, India 3 Mechanical Engineering Department, NIT Warangal, Telangana, India 4 Deprtment of Mechanical Engineering, Graphic Era, Dehradun, Uttarakhand, India

ABSTRACT Jatropha Curcas is generally called as Jatropha. Oil extracted from Jatropha can be considered as a non-edible oil and can be yielded in a barren land with low water availability. Even the Indian Government also promoted this Jatropha derived oil as one of the promising alternatives for fossil fuels. Being Jatropha is a sustainable yield, environmentally friendly, good in yield different aspects in making use of alternative fuel as processing its seeds, composition, quality and advanced techniques has been discussed in the chapter. *

Corresponding Author’s E-mail: [email protected].

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Keywords: Jatropha Curcas, biofuels, Green House Gases, Renewable energy,

INTRODUCTION The most traditional biofuels are supplied from outstanding rural food crops that need high-end developmental growing regions, such as corn, wheat or sugar beets. Over the 21st century, the biofuel industry would grow rapidly (Demirbas 2008). Around 84% of the world’s biodiesel production is mixed with rape oil. Sunflower oil (13%), palm oil (1%), soybean and others (2%) make up the remaining part. About 95% of biodiesel now comprises of frozen oils. Brazil’s soybean oil is almost 85% B5 (5% biodiesel in green diesel). In order to combat these adverse circumstances, biodiesel is being slowly produced from non-palatable oil and waste cooking oil (WCO). Non-consumable oils have the bonus of not speculation that they challenge the nutritional exhibition with tasty oils. Because of the increased use of soil to produce biofuels, biofuel crops are currently rival food crops (Odling-Smee 2007) Therefore, the results of the economy are contingent on them. In comparison, the usage of food crops to manufacture biofuels encourages pollution and performs the ‘climate burden’ of emitting 17-42 times as many climate dioxides as the annually toxic ozone (GHG) content, which is degraded through nonrenewables dissipation. At the other side, squander biomass or biomass based biofuels produced on a limited basis with permanent species render practically null carbon obligation (Fargione, Hill et al., Searchinger, Heimlich et al. 2008). Jatropha has a few points of concern, which are opposed to different oilseeds, with respect to biofuels: (i)

Jatropha will flower without a land of people, which is usually found in powerless populaces. In this context, a meaningful social effect will be accomplished by removing policy programs, increasing the population in rural areas and delivering community incomes and energy;

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(ii) showed the achievability of the biodiesel (Carels 2009) (iii) can be very well sprinkled on traditional CI engines as flawless oil or biodiesel (Carels 2009) (iv) The ecological effect of palm oil becomes lower before the implantation becomes carried out by the normal biological systems (Laurance 2007, Stone 2007, Stone 2007, Malhi, Roberts et al. 2008, Venter, Meijaard et al. 2008) National Auto fuel Policy seeks to make progress on the creation, by providing innovative work (R&D), of biofuels from inexhaustible sources. This seeks to maintain a sustainable, secure, fair and consistent supply of high quality automotive fills to support social and monetary improvement. Many of the key elements for this strategy are to gracefully extend sources and reliance on each particular source.

Switch to a Renewable Energy Network in India In the following few decades, petroleum derivatives will continue to occupy a predominant position in the energy situation in India. In order there is a small, non-sustainable, contaminating and, consequently, wisely exploited supply of conventional or non-renewable energy supplies. Again, renewable energy supplies are natural, non-contaminating and limitless for all purposes. India has an array of renewable electricity sources. Their usage will also be encouraged in any way imaginable. The vital safety of India will remain helpless until elective fills are supplied from indigenously inexhaustible feedstocks to replace or replace entirely oilbased energy sources. For biofuels in view, the nation has a range of viable solutions that guarantee conservation of fertility. Biofuels are well-equipped energy sources and their usage will resolve global questions over carbon emission regulation. The section of transport was described as an essential portion of clay. It convinces consumers of biofuels to take into consideration the regulations on the modification of emissions of cars for the prevention of

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air pollution. India has a total region of 328 hectares, of which roughly 142 hectares for agribusiness are used. Through 2030 Indians would cross $1.5 billion from about $1.21 billion last year. It would require around 185 ha of rural land, both in terms of preservationism and the expectation of clear agricultural productivity, to take care of this large population. At the cost of food goods, the production of biofuels will yield catastrophic effects, even in peace, in terms of Indian social interest. The production of biodiesel will also improve steps and standards to ensure the operation of the rural industry and the most significant is that the food health of its citizens is accomplished. The national strategy on biofuels will concentrate on the expanded usage of residual land for adjacent biofuels.

Why Is Jatropha so Sustainable Exciting? The Center for Jatropha Promotion and Biodiesel have been reported in India for the development of biofuels and carbon pollution in view of the presence of Jatropha in India, up to 13 additional non-food olive oilseeds and trees may be used. The following Centers have been established, namely Identi Fij (Camelina Sativo), Juan (Helianthe tuberosus), Hibiscus cannabinus, Henaf (Carania pinnato), Kokum (Garcinia indica), Moringa (Garcinia indica), Mahua (Madhuca indiica), Neem (Azadirachta indica) and Simaruba (Simarouba) and Simarouba (Simaringa oleifera). Jojoba is found in South Arizona, South California, South Arizona Northwest of Mexico. The Rajasthan State Government has allotted 110 ha, 70 of them for the Jojoba farm. Pongamia has only a few nitrogen fixtures which produce 30-42 percent of the seeds that contain oil. Mahua is one timberland tree with a big capacity to produce approximately 60 million tons of non-palatable oil in India per year. The worldwide expanding demand for extracted oil from beaver beans has now been assured, for more than 700 applications, from medical goods and improvement agents to biodiesel plastics and ointments. Growing ha of beans planted in semi-parched and dry premises yield from 350 and 900 kg each. Despite the recent use of corn seed oil (Zea mays), movement in the

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field of bioenergy increased with oil from palm, soya, and assaults in the past couple of years, and from many different oilseeds (aside from, for example, those above referred to, Shorea robusta, Mesua ferra and Mallotus Philippines). A jatropha tree regularly assimilates roughly 8 kg of CO2. It causes about 2,500 trees to be grown in a hectare, with an estimated 40–50 years of sequestration of around 20 tons of CO2. In comparison, it has a standard annual biodiesel supply of 3,785.4 litres and total biomass of 3,500 kg. The usage of biodiesel lowers the pollution of gasoline by 3.2 kg CO2 / litre. Biodiesel can eliminate 2.5 kg CO2 / litre or 9.2 large volumes of carbon dioxide for each hectare at an output of 78 percent. In comparison, the biomass that is produced after oil extraction may induce a decrease in carbon-based on the energy extracted.

The Jatropha Biodiesel Regional Project In April 2003 under the aegis of the Indian Planning Board, the Government of India initiated its Biofuel Critical under BIO-FUEL and submitted its report, which sets out a specific, multidimensional strategy to replace 20% of India’s gasoline consumption. The National Planning Commission has established the Ministries for Energy, Urban Development, Poverty Alliance and Ecology, among other bodies. On 11 September 2008, published on the biofuel strategy. During its meeting, the Union Cabinet approved the Ministry of New and Renewable Energy’s National Biofuel Policy and the creation of a dedicated National Biofuel Coordinating Committee headed by India’s Prime Minister and the Cabinet Secretary’s Board for the Biofuel Steering Committee. One of the goals was to blend petro-diesel with 13 million tons of biodiesel in 2013 (+ /1000 times in contrast with the existing environment of jatropha growth and production), primarily supplied with non-palatable Jatropha oil and, more recently, Pongamia. In planning 11 million hectares of Jatropha, the program will become a “National Mission.” It will also require the preparation of an enormous number of partners, such as employees,

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networks, companies, oil companies, businesses, industry, the financial segment, and Government and most of its institutions.

Jatropha’s Productivity The conservation of Jatropha in the elders of the ranchers is most essential for seeds and oil production. The natural product yield in Jatropha is stated to vary from an unassumed significant part of 1 kilogram per plant up to a limit of 12 kg per plant. Typical productivity obtained by certain foundations and associations, organized and half kg per farm. This efficiency has been detailed by a few enterprises of innovative work led by the DBT and NOVOD Boards (in India). A few organizations have demonstrated plant efficiencies of 2 kg per plant in comparison to these results. In its system for the hybridization of advanced and intraspecific systems, NBL picked 2 kg mainly rental plants for every plant and hybridized them. The most notable usual yield was an estimate of 5.2 kg in the NANDAN-1 half-breed. Intra-explicit half-breeds developed by the NBL is checked under rainfed and flooded conditions.

Jatropha and Barren Land In the current evaluation by the Indian Government, 16 percent of the region has been recognized as no man’s land (> 50 m ha). Recalling that 221 million poor people in India and 70 percent of the poor are small peripheral ranchers and landless workers in India, no one must try to produce the financial benefits necessary to helpless ranchers and workers with no help. Jatropha is ideal for growing in compromised drylands as one of the plants in the dry districts of Mesoamerica. The Jatropha is now dispersed by the Portuguese Regional Army and is also very suitable in many African and Southern Asian countries for semi-dry tropical environments. Jatropha is sterile and contains less than 200 mm of water a

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year. System of drought-falling leaves expands the extent of the natural problem in the dirt, making Jatropha the right one for depleted land yet the right one to restore it. This protects the world and catches disintegration with its dense root system. Develop herbal goods that are rich in noneating fat, and that can be used for a few reasons and are not eaten by livestock. In this respect, Jatropha may be a decent way to re-establish and compensate additional money for the polluted terrain usually belonging to poor and small farmers. Late production of energy plants was begun to develop a technique that served both the energy and food needs. A report by the Biofuels Commission (2003) the Indian Government (2003) would better fulfil Indian requirements and Pongamia pinnata out of a large number of oleaginous plants. To raise Jatropha, it is not necessary, because Jatropha has the innate ability to bloom with corrupted and small terrains, to abandon the area under development of food and green harvests. Jatropha is a fast-growing yield that is not reproduced by dairy animals and goats capable of withstanding cruelty to nature. The Biofuels National Mission has approximately 13.4 million ha of identity for Jatropha in India. It includes terrible, marginal, lost, squandering and various areas such as roads, highways, railways, home station and land bonds in arid areas and semi-arid regions in the short term. Curcas and Pongamia pinnata are manors. If achievement is achieved on common grounds, low-field soils should be included that can be restored financially in a practical manner under the Jatropha Ranch. Non-palatable oil may be used for biodiesel development by obtaining information-based and genial helpless methodology. As a flawed biological process, an excellent win-win situation improves vocations, healthy conditions and allows energy to flow from endless sources.

Jatropha Fruits In either scenario, on tiny houses, in realistic words, J. Since the earliest point, they roll down Curcas natural goods. They may also be treed while natural goods are profoundly earthy or cold. It resulted in a mixture

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of manufactured goods of varying temperature and quickly infectious circumstances. The oil is relatively low quality and is free of unsaturated fat (FFA) up to 12 percent, separated from these blended assortments. To retain healthy seed and oil quality, J. Curcas organic items, although yellow in colouring, are best picked. At this point, the abrasion strength relative to the heaviness of the natural product is less. It is ideal once collected to remove the sheath from the organic product to uncover dark seeds immediately. The new sheaths may be returned for J as a mulch—plants with Curcas. The seeds must be dried on a fine, dust-free surface under daylight. Under intense heat, the humidity of the seeds dropped below 7% after three days. When the dried husk is a liquid, on the other side, the whole natural products may be dried for 4–5 days under the sun and placed away to that degree. Before seed is squashed to remove the oil, the dried organic products can be de-husked. The dry husk has excellent use and a productivities level of 14 to 17 MJ kg – 1 for a dry question hypothesis Semitic seeds of less than 7% can be put in moist conditions for 3.5 years without any loss of quality. Air dampness is the period of efficiency. When the conditions of capability are clear, cold (around 4°C) and dull seeds can be harvested for more than one year without injury.

Seed Processing The application of the screw presses currently squashes Curcas seeds. The whole seed is compressed into a pale mass which is formed by the screw, without the oil being completely isolated. The shell is squashed. The seeds are warmed up to 40°C once in a while so that before pounding the oil becomes ever more versatile. The amount of oil depends on the oil quality, but the majority of residual oil in the seed cake after the squash is between 6% and 10%. 4 kilos of dry Jatropha Curcas and broad screw yield presses of 1 kilo of oil and 3 kilos of the panicle. The oil produced through the screw-squeezing is high enough for biodiesel change.

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Up until this point, no attempt was made to remove the oil by dissolving the Jatropha extraction of seeds of the Curcas. It is only possible monetarily for a considerable extent (Adriaans 2006).

Oil and Composition Attributes It can be well known that the figures of various characteristics range from seed content, style of screw press and form of filter to an unmistakably complete degree. In better circumstances, it is possible to obtain Jatropha Curcas oil meeting the German Norm for usage as fuel with vegetable oils aside from the volume of waste. Despite physical isolation, the composition of materials such as, for example, P, Ca, and Mg may be decreased using a compound adsorbent extraction to reduce the debris material. The herbal esters in Jatropha Curcas are toxic compounds. In an alternative chapter below, this is handled in depth. The composition of unsaturated fats further defines the essence of Jatropha Curcas oil as a feedstock for biodiesel. The expansion of Curcas oil in two bonds decreases oxidative safety and hence the conserving quality of the product, rendering it appealing to higher oleic corrosive convergence—the amount of cetane in the oil forms of strongly oleic corrosive material. The amount of cetane is the proportion of deferred fuel usage from the beginning and rises to 55 the existence of oil. In order to render colder regions more pleasant and thus suitable for winter, an optimal mix of unsaturated fats is needed again. Jatropha Curcas oil, obviously given from mixed seed plots, has in any case been used as a biodiesel source when the processing is done in a group system. Screw squeezed The D. The consistency requirements recommended in the European standards EN 14214 are considered to be Curcas oleo ethyl ester (Jatropha Curcas biodiesel) produced out of these oils.

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Qualities of Jatropha With the Euphorbiaceous family, Jatropha has a location. This is a good shrubbery or low (3–10 m high) for woody dry season that will develop on limited areas needing only minimal quantities of soil, manure, and pesticides. Jatropha is located in tropical and subtropical districts in Africa and Asia, beginning with South America. The regions for the growth of Jatropha are found in a belt from 36° S to 31° N. In either case, this belt just speaks of an assessment of future Jatropha production territories. (Adriaans, 2006, Li, Lin et al., 2010). Post-conditional superior outputs are monitored for development under semi-dry conditions with average temperatures ranging from 20°C to 28°C, and somewhere in the range of 250 or 3000 mm in precipitation, although Jatropha is developing in a broad range of conditions. Quite sandy and gravely soils are also perfect for the growth of Jatropha (Openshaw 2000, Achten, Verchot et al. 2008). While Jatropha that grows in conditions that remember hollow soil and water constraints (just precipitation), it is evident that the yield of Jatropha is often greatly influenced by the conditions under which the trees are grown. For both situations, it is essential to allow a full chain investigation before Jatropha is advanced for the development of biodiesel for the respect of another crop for energy, as a first phase in resolving the growth of energy or lack of renewable energy supply.

Techniques in Advancing Jatropha Jatropha is commonly cultivated in Brazil, Honduras, Thailand and areas of India. It is currently progressing in South Africa, Brazil, Mali and Nepal. Some governments, universal associations, national organizations and NGOs are promoting Jatropha planting and utilization. Plants and other Curcas is bearing petroleum. It is comprised of the World Bank, the Foreign Plant Genetic Science Institute in Germany, the German Technical Assistance Programs, the Rockefeller Foundation and the Zimbabwe Plant

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Oil Producers Group, as well as the United States and UK-based NGOs (Jones and Miller 1992, Heller 1996, Henning 1996, Gübitz, Mittelbach et al. 1997). Two primary goals of these operations are the utilization of oil plants and their components in order to boost the monetary and land usage, and the autonomous productivity and filling of regional territories. This can be achieved without breaking absolute horticultural returns or looking for land that has a better opening door in different applications. One of the most notable plant oil species was the jatropha Curcas, particularly in Brazil, Nepal and Zimbabwe. Territories in these three areas, which have already been evolving such forms, have been selected as exhibiting places for the use of sufficient creativity of plant oil. Specific goals were specified in order to reach the stated destinations. The above can be described in the following terms: 

 



In the case of power siphoning (water system), grain manufacturing, transport and electrical era, progress the usage of plant oil as a fuel in fixed or portable engines. The usage of plant oil as a viable substitute, renewable fuel for heating, illumination and warmth should be energized. Reduce the need for cleansers and medications, ointments, organic substances, composts, bug sprays, by promoting financial exercises in countries regions and using the effects of such plants for assembling cleaner. In order to improve nature, disintegration control, soil fertility improved, higher microclimate and ozone harmful substance (GHG) moderation improve land recovery.

Although individual states, NGOs and participating organizations’ general goals may be highly commended and targeted at, their priorities can be inconsistent in reaching such objectives. Some organizations advocate jatropha oil as an energy source, despite the lack of numerous uses and plant products without examining the financial aspects of oil growth and output thoroughly. The intended usage of plant oil will lead farmers and producers to fund end-users without competitive markets for

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oil and other products. This can deter further financial development, hinder personal fulfilment upgrades and alleviate delays in pumping plant oil for this purpose. The jatropha oil is an essential part of the plant but is just one of the ingredients. The usage of this oil for explanatory capacity seems to have been stressed heavily. The use of jatropha oil in diesel engines is still an early struggle, and it is too uncertain whether or not the plant oil can compete against diesel fuel at its present cost, irrespective of whether petroleum products are compelled with ‘carbon charges.’ Consequent, the usage of Jatropha and other plant oils for thought process control are generally subject to different restrictions and monetary components. They can be figured out completely, rather than searching at what may be defective solutions, and in comparison, to the elective usage of gasoline. At some stage when oil spares (non-renewable energy), and a significant worldwide carbon charge for petroleum goods is required, fossil-based biomass fluid power will prove severe. In the meantime, countries will get interested in the production and use of adaptable species, such as Jatropha, so that they can obtain this knowledge as long as oil takes diesel seriously, etc. That may be achieved by utilizing the jatropha plant and its derivatives for different purposes. The usage of the plant oil for family cooking in country territories to fill up for fuelwood is another purpose listed above which should be reproached. The expense of purchasing petroleum is usually much higher than that of lamp oil (or fuelwood purchased). Nevertheless, regional residents use oil for illumination sparingly, but also for food. Regardless of how petroleum oil can be produced at virtually the same expense as lamp oil, country citizens are usually hesitant to pay for cooking fuel, if it is plant oil, wood oil, lamp oil e. Rustic people are unlikely to consume crop growth and compost if fuelwood is scarce. One of the goals listed above was to use jatropha oil. To cook in countries so that deforestation could be reduced. The usage of fuelwood, since it may cause any forest destruction, for cooking in countries causes practically nothing except deforestations. For an extended period, the main factor behind deforestation is that the horticulture land is clearing due to

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the rise in population. To order to deter deforestation, agricultural productivity needs to be improved, aside from progressively effective family relationship practices. J. Curcas can take on a job through land recovery, disintegration management, microclimate protection and improvement. Dissolved lands and other issue localities may be used with Jatropha. Jatropha clasps can support various yields of all land types by the preservation of species, enhancement of the microclimate and humus. It could also be enhanced in small to wide future regions as an economically sustainable return. In this sense, such plants will rather than compete with them, be regarded as supplementary to agricultural harvests. Many company returns may be loaned to Jatropha or safe garments. Those involve espresso, planting, production of tobacco, etc. These valuable harvests can be generated at that stage without damaging the species while at the same time, enticing products can be supplied from the barrier itself. Likewise, Jatropha may be used as a supplement for cable fencing and round field positions, since it would be achieved along the path and line. In Mali, Jatropha as a supportive plant is the primary aim. A survey of the two types of clamping can show that live clamping is significantly more practical than wire clamping. Current knowledge and possible destinations by weather, a form of soil and current users should be registered. Jatropha should not be limited to trouble regions, though, included in other fields in which specific planting systems may be applied or where it has a slight leeway.

ORCID AND SCOPUS IDS ORCID Scopus

https://orcid.org/0000-0002-5781-4764 57210448403

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REFERENCES Achten, W. M., L. Verchot, Y. J. Franken, E. Mathijs, V. P. Singh, R. Aerts and B. Muys (2008). “Jatropha bio-diesel production and use.” Biomass and bioenergy 32(12): 1063-1084. Adriaans, T. (2006). “Suitability of solvent extraction for Jatropha curcas.” Eindhoven: FACT Foundation 9. Carels, N. (2009). “Jatropha curcas: A review.” Advances in botanical research 50: 39-86. Demirbas, A. (2008). “Biofuels sources, biofuel policy, biofuel economy and global biofuel projections.” Energy conversion and management 49(8): 2106-2116. Fargione, J., J. Hill, D. Tilman, S. Polasky and P. Hawthorne P. (2008). Land clearing and the biofuel carbon debt. Science, Citeseer. Government of India (2010). Wasteland Atlas of India, Government of India (GOI), Ministry of Rural Development, Department of Land Resources, New Delhi. Gübitz, G. M., M. Mittelbach and M. Trabi (1997). Biofuels and industrial products from Jatropha curcas, Dbv-Verlag für die Technische Universität Graz. Heller, J. (1996). Physic nut, Jatropha curcas L, Bioversity international. Henning, R. (1996). “The jatropha project in Mali.” Weissensberg, Germany: Rothkreuz 11. Jones, N. and J. H. Miller (1992). “Jatropha curcas: A multipurpose species for problematic sites.” Jatropha curcas: a multipurpose species for problematic sites. (1). Laurance, W. F. (2007). “Switch to corn promotes Amazon deforestation.” Science. Li, Z., B.-L. Lin, X. Zhao, M. Sagisaka and R. Shibazaki (2010). “System approach for evaluating the potential yield and plantation of Jatropha curcas L. on a global scale.” Environmental science & technology, 44(6): 2204-2209.

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Malhi, Y., J. T. Roberts, R. A. Betts, T. J. Killeen, W. Li and C. A. Nobre (2008). “Climate change, deforestation, and the fate of the Amazon.” Science 319(5860): 169-172. National Auto Fuel Policy (NAP), www.petroleum.nic.in/autopolicy.pdf. (2003) Odling-Smee, L. (2007). “Biofuels bandwagon hits a rut.” Nature. Openshaw, K. (2000). “A review of Jatropha curcas: an oil plant of unfulfilled promise.” Biomass and bioenergy 19(1): 1-15. Searchinger, T., R. Heimlich, R. A. Houghton, F. Dong, A. Elobeid, J. Fabiosa, S. Tokgoz, D. Hayes and T.-H. Yu (2008). “Use of US croplands for biofuels increases greenhouse gases through emissions from land-use change.” Science 319(5867): 1238-1240. Stone, R. (2007). “Can palm oil plantations come clean?” Science 317(5844): 1491-1491. Stone, R. (2007). “Last-gasp effort to save Borneo’s tropical rainforests.” Science 317(5835): 192-192. Venter, O., E. Meijaard and K. Wilson (2008). “Strategies and alliances needed to protect the forest from the palm-oil industry.” Nature 451(7174): 16-16.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 9

EXPERIMENTAL INVESTIGATIONS ON INFLUENCE OF PREHEATING THE JATROPHA BASED STRAIGHT VEGETABLE OIL THROUGH EXHAUST GAS FRAMEWORK ON AN IDI CI ENGINE P. S. Ranjit1,*, Venkateswarlu Chintala2, A. Veeresh Babu3 and Yashvir Singh4 1

Professor, Dept. of Mechanical Engineering, Aditya Engineering College (A), Surampalem 2 Associate Professor, School of Engineering and Applied Sciences, National Rail and Transportation Institute (Deemed to be University) Vadodara, Gujarat, India 3 Associate Professor, Mechanical Engineering Department, NIT Warangal, Telangana 4 Associate Professor, Dept. of Mechanical Engineering, Graphic Era Deemed to be University, Dehradun, Uttarakhand, India



Corresponding Author’s E-mail: [email protected].

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ABSTRACT Depletion of fossil fuels, an exponential increase in the price of barrel crude oil, engine-out emissions reached to an alarming level, to promote local employment at the rural level, and to fulfil the words (Self -reliance) of the honourable prime minister of India. For sustainable development, an experimental investigation was done on Jatropha Curcas based preheated Straight vegetable Oil. In-direct Injection CI engine was selected, being most commonly used by the farmers in agricultural land. Performance parameters like Brake Thermal Efficiency (BTE), Brake Specific Energy Consumption (BSEC), Combustion Characteristics like P- Theta, Differential Heat Release Rate (DHRR), Integral Heat Release Rate (IHRR) and Emissions like NOx, CO, CO2, HC and Smoke were evaluated and presented in this chapter for suitability to make use in internal combustion engines.

Keywords: Jatropha Curcas, framework and IDI engine

performance,

emissions,

preheating

INTRODUCTION The Earth’s constrained stores of non-renewable energy source have involved worldwide worry as these are under danger of consumption due to over misuse. Falling apart natural conditions have become an issue of consistently expanding overall open concern. As of now, the ignition of petroleum derivatives is the prevailing worldwide wellspring of CO2 discharges. There are endeavours far and wide to shield nature from further weakening. These variables have prompted a worldwide creative quest for inexhaustible wellsprings of energy. Thus, a few other options, primarily sustainable power source alternatives have been found and investigated. A few achievable advances in the territory of sun oriented, wind, and biomass have been found, tried, culminated, and are expanding in notoriety. Even though the more significant part of the sustainable power source advances are more eco-accommodating than regular energy choices, their selection is moderate in light of different factors, for example, economic imperatives, absence of flexibly, and specialized ability of clients. Further, the

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utilization of these advancements is as yet restricted essentially to fixed activities, primarily because of innovative impediments and helpless financial matters. Biofuels are always gaining fame because they replace the current petro energy sources quickly. We require no alteration of the engine or gasoline. The oils obtained from live plant sources are mainly biofuels. Sap and plant seeds may contain these oils. Plant oils are inexhaustible and naturally contain low sulfur. Because biofuels are more expensive than petroleum products, their use in IC is limited throughout the broad use of biofuels (Goering E 1982, Vellguth 1983). The use of straight vegetable fuel (SVO) in the diesel engine was well known before the question of other successful options – liquor. There are specific difficult characteristics, particularly their thickening, which limit SVOs to be used for pressure start engine as a fuel. The high molar mass of oils and the proximity of unsaturated fats are responsible for this. Polymerization of unsaturated fats at high temperatures can lead to specific problems. It occurs as interconnection starts between objects, inducing massive agglomerations and resulting rubberization. The greater viscosity of SVOs causes non-helpful atomization of fuel which causes poor fuel inflammation and carbon declaration on the injector and valve position, causing genuine engine failure. The injections get tampered after a few hours when direct infusion engine are running with SVO’s. Such gagging often triggers funny atomization of gasoline and bad smoking. Incompletely torched vegetable oil flows through the chamber dividers and weakens the oil grafting and extends the oil grafting. Despite the SVO constraints described above, it could be conceivable to use them for some low-end applications for instance enhancement of single-chamber diesel engines commonly used in rustic/agricultural applications. That, though, will gracefully entail extra fuel because start and stop of the diesel engine must be achieved such that flawless oil is not claimed on different engine parts, which will affect cold start and operation of the engine. In order to reduce the thickness of the admitted oil by an appropriate warmth trading gadget, the fuming warmth of the engine could also be used. Assays on various foundations have shown that engine using flawless SVOs can work

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viable for around 250 hours by reconciling the aforementioned additional sub-frames. Each vegetable oil and animal fat contains mainly triglycerides (otherwise known as triacylglycerols). The three-carbon base of the triglycerides has a strong hydrocarbon association with each carbon. The chains are united by an oxygen particle and carbonyl carbon, a doublesided, second oxygen-carbon molecule. The contrasts among the oils from different sources identify the length of the unsaturated spine fat chains and the amount of carbon-carbon double securities in the chain. The largest unsaturated fat chains are 18 carbons in length from plant and animal oils, with nil and three double-security securities somewhere. Unsaturated fat chains without double securities should be swallowed and double securities unsaturated. Table 1 demonstrates one each of the five essential unsaturated fat chains in oils and fats has been calculated similarly. (Knothe, 2005). Methyl esters’ properties are strongly affected by the presence of double bonds in the unsaturated fat chains. The twisting of the particle caused by the double ties prevents the formation of useful piers that decreased the gel’s biodiesel temperature. The soaking in fats transforms into the fluid at elevated temperatures—the palm and coconut fat temperature, edible hydrogenated oils, for example, and certain tropical oils. Biodiesel can gel from these oils at low temperatures. The carbon-carbon double securities are susceptible to oxidation by oxygen in unsaturated oils and fat. Similar to the cases of linoleic and linolenic acids, this effect is amplified when the securities are combined (two dual securities, isolated by two individual bonds). These unsaturated fats are 50-100 times faster to oxidise than oil corrosive fats with uncombine double safety. Soaked unsaturated fats do not rely on this kind of oxidative attack. In the exchange between cold stream, oxidation power and cetane numbers, the choice of oil or fat feedstock decides the situation with the subsequent biodiesel. Gradually soaking feedstock biodiesel would have more significant cetane numbers and improved oxidation dependability, but also have powerless virus streaming characteristics. Biodiesel from low degree fatty oils should have more robust stream properties, but less cetane and oxidative power (Misra and Murthy 2010, Haile 2014) (Dunn and Moser 2005).

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It is not new to use vegetable oil as diesel fuel. Rudolph Diesel’s first diesel engine was designed with vegetable oil. At the Paris Exhibition in 1900, he used nut oil to drive one of his engines (Demirbaş 2002). However, then, vegetable oils have been reduced to coal because of the limited versatility over the last century of the world’s accessibility to oilbased non-renewable energy sources. Throughout the 1970s, energy crises have introduced an ever-increasing number of issues about the usage of energy as a replacement for the oil commodity and the increasingly rising expense and weaknesses of oil supply, the concern for biodiversity and the effects of ozone pollution during recent decades. Vegetable oils have their beneficial conditions: they are accessible everywhere on the planet as a matter of prime importance. They are inexhaustible as year after year oilproducing crops can be grown. Third, the soil is “greener,” and often there is just one sulfur in the soil. In several formal studies, vegetable fuel is thereby made. The efficiency testing of diesel engines is often conducted on vegetable oils. A variety of studies have been carried out, and research findings have indicated that vegetable oils substitute diesel fuel functionally. (Pramanik 2003, Ramadhas, Jayaraj et al., 2004). Vegetable oils have about the same calorific benefit as diesel fuel. An inborn high thickness is, in any event, a significant downside to vegetable oils. Current diesel engines are framed with fuel infusion that is sensitive to changes in thickness. High thickness can prompt fuel atomization, inadequate burning, fuel injectors coking, ring carbonization and fuel aggregation in grafting power.

MATERIALS The Jatropha Curcas is selected as the primary engine for research operations, also known as Jatropha. From Jatropha seeds at the engines and biofuel testing laboratory, UPES, Dehradun was produced straight vegetables oil (SVO) in Jatropha. Table 1 displays the physiochemical characteristics of the resources used in the exploratory test. Work was

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performed on an In-direct injection (IDI) Diesel (CI) engine with a preheated SVO at various preheating temperatures of SVO, which ranged from 400C to 1200C using fumes. Table 1. Physiochemical properties of Jatropha SVO (Ranjit and Chintala 2020) Description Specific gravity Kinematic viscosity, cSt at 40oC Kinematic Viscosity, cSt at 90o-100oC High Calorific value, MJ/kg Low Calorific Value, MJ/kg Flash Point, oC Fire Point, oC Pour Point, oC Water content, mg/kg Sediment, % by mass Conradson carbon residual, % by mass Total acid number, mg KOH/gm Total base number, mg KOH/gm

Jatropha SVO (tested) 0.935 34.33- 36 4.73 41.2 39.1 235 262 -10 186 Nil 0.53 18.8 0.52

Test method IS: 1448 (P-32) 1992 lS: 1448 (P-25) 1976 lS: 1448 (P-25) 1976 IS: 1448 (P-6) 1984 IS: 1448(P-6) 1984 IS: 1448 (P-21) 1992 lS: 1448 (P-69) 1969 IS: 1448 (P-10) 1970 ISO: 12937 IS: 1448 (P-30) 1970 ASTM D-189 IS: 1448 (P-2) 2007 IS: 1448 (P-86) I977

METHODOLOGY Bi-directional 91 N-m M/s. Dynomerk made eddy current dynamometer was connected to a 7.35 kW IDI diesel engine. A Magnetic filer was connected to the eddy current dynamometer to filter the incoming water which will flow through tiny holes of the dynamometer to dissipate the heat generated during its operation (PS Ranjit 2014). Given pre-heating straight vegetable oil, a two-way valve provided diesel/SVO gracefully for starting and stopping the engine. The test engine was always started with conventional diesel fuel and later changed to SVO, in order to overcome the initial problems. To ensure that the SVO-90 filtered fuel out before the actual time, the engine had been permitted to

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operate for around 15 to 20 minutes. The engine was substituted with diesel fuel and worked for a further 20 minutes to ensure lone diesel fuel was kept inside the structure of the fuel line.

Figure 1. Engines Test Bench.

Figure 2. Schematic representation of Engine test bench.

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WASTE HEAT UTILIZATION FOR PREHEATING THE SVO The SVO to 400 to 1200C is preheated by the usage of the waste heat recovery system, a new feature of the current review. The gas was collected by the sparkling fire of the exhaust gases by preheating device. The air was transferred from the gases to SVO by a counter stream shell, and cylinders heat exchanger. Figure 3 shows a schematic diagram and a pictorial view of the preheating framework. The gas temperature of engine fumes was between 3600 and 5400C and depended on the engine load. Because of this temperature ride, a standardized and developed innovative architecture for low-temperature heat exchangers. The efficiency of the heat exchangers was about 75%, enabling the SVO to hit around 400 C to 1200C.

Figure 3. Pictorial and Schematic representation of Heat exchanger.

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INSTRUMENTATION Thermodynamic estimates have been caught in the chamber by considering a standard 100-cycle AVL GaPO4 GH15DK model based on double shell pressure transducer was used to measure cylinder pressure. This pressure transducer was used to ensure the proper uncovering of the sensor for combusted objects against straight movement of the cylinders. The AVL 365 cc models, with a 720 pulses crank angle (CA) encoder were mounted on the one side of the engine and synchronized with a Top Dead Center (TDC). This CA encoder changes into a computerized sign over the simple force ‘position’ of the engine rod and moves to the cutting-edge AVL Indi Smart 612 combustion analyser, for the p-θ and the heat release rate.

EDDY CURRENT DYNAMOMETER Operating Procedure for Dynamometer and Control Panel    

  

Connect mains I/P to the panel & switch on all instruments. Switch on the water pump and ensure proper water pressure through dynamometer Make all the required preparations to make engine ready for trials. Check for a ready signal on Dynamometer Controller. If it is failed, then press ‘RESET’ Switch, and ensure the ‘READY’ signal. Switch ON the ‘EXCITATION’ switch, this switch enables excitation current to Dynamometer coil. Set the Demand potentiometer at 0. Start the engine and increase throttle to increase the speed of the engine.

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Rotate the demand pot in the clockwise direction to load the dynamometer. Increase the throttle to 100% and increase the load on dynamometer till engine RPM drops to the desired RPM. Observe and note down the Torque reading.

Current Setting Procedure for Dyno Controller      

Press the Excitation switch and conform the Excitation lamp is glowing. Keep Dyno in INT mode. Select I = C mode When demand pot is at Zero position conform that current through dynamometer should Zero. Increase the demand and observe the current through dynamometer should increase correspond to demand. When set Demand pot is at its max position current through Dyno is 6 Amp if it is not then adjusted it with a current gain pot on PCB AULC1.

Pot Position for Various PCB 

Torque Indicator P1 P2



DMC/MC/LI 2

P4 P6

ZERO ADJUSTMENT

FSD (FACTORY SET )

SPAN ADJUSTMENT

O/P CALIBRATION FOR (10V) (FACTORY SET )

3 Mode Dynamometer Controller

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P1

+10V REFERNCE (FACTORY SET) P8

P9 P7

P4 P5

P6

DMC/AU/LC/2M 1

P10

P2

P3

D2 T=C PID SETTING MODE SELECTION INTERLOCK

I2 T=C PID SETTING P2 T=C PID SETTING D1 N=C PID SETTING

RPM ANALOG O/P SETTING

I1 N=C PID SETTING GAIN SETTING OF TORQUE I/P

P1 N=C PID SETTING

DMC/AU/LC/1

P1 P2 P3 P4 P5

CURRENT FEED BACK CURRENT GAIN CURRENT TRIP SETTING TEMPERATURE 2 TRIP (NON-DRIVING END) TEMPERATURE 1 TRIP(DRIVING END)

Figure 4. PCB Locations of a Dynamometer.

ENGINE OUT EMISSION MEASUREMENT In addition to the existing engine exhaust emission system, indigenously designed sampling system was developed to authenticate the engine discharges. The sampling unit has been configured and incorporated into the engine fumes line to monitor the pulsing advancement of engine fumes gas to ensure the validity by the official delegate testing of smoke pollution numbers. Di-gas 4000 and 400 Smoke meter are separately used for the quantification of gases such as CO, HC, NOx and smoke of AVL make. The smoke meter takes a shot at the light-assimilation turbidity standard. NDIR (non-dispersive infrared) guidance (PS Ranjit April 2014).

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RESULTS AND DISCUSSION Performance

Figure 5. Brake Thermal Efficiency.

Figure 6. Brake Specific energy Consumption.

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Variation of Brake Thermal Efficiency (BTE) with engine load for different preheating temperatures was represented in Figure 5. As the load increases brake thermal efficiency was increased. Maximum brake thermal efficiency was observed at 80% load. Being an IDI engine due to the high surface to volume ratio of the divided chamber (Pundir 2010). Maximum BTE of 25.38% was observed at a preheating temperature of 900C, which is higher than any other preheating environment but still, 2.03% lesser than the neat diesel operation. Figure 6 depicts the change in brake specific energy consumption (BSEC) with varying the load and preheating temperatures of Jatropha Curcas Straight vegetable oil (SVO). At maximum efficiency point, 14183.1 kJ/m3/deg. was observed, which is lower than any other preheating temperature environments and higher by 2,348.51 kJ/m3/deg. compared to diesel operation.

Combustion Figure 7 represents the inside cylinder pressure Vs. Crank angle for different preheating temperatures at peak efficiency point. At 900C preheated temperature of Jatropha SVO, 40.96 bar pressure was developed at 100 aTDC which is higher and as well as nearer to TDC when compared to all other preheating temperatures, but still 2.65 bar less than the pure diesel operation at a crank angle of 8.50 aTDC. Even it can be observed from Figure 8 that, with preheated 900C, the second phase of Differential heat release rate was observed compared to earlier phase because of its oxygenated fuel better participated in the second phase. Figure 9 represents the variation of Integral heat release rate with Crank angle.

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Figure 7. Cylinder Pressure.

Figure 8. Differential Heat Release Rate.

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Figure 9. Integral Heat Release Rate.

Emissions Figure 10 represents the variation of NOx concerning variation load for preheating temperatures. Maximum NOx was observed at a maximum efficiency point, i.e., 80% load is 291 ppm, which is 24 ppm higher than regular diesel operation.

Figure 10. NOx Emissions.

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Figure 11. Smoke Emissions.

Figure 12. Carbon Monoxide Emissions.

It is observed from Figure 11, shows the variation of smoke concerning the change in preheating temperatures as well as at different loads. At maximum efficiency point and preheating temperature of 900C, 57.3 HSU was registered, which is 5.3 HSU higher than regular diesel operation and lower than all other preheating environments.

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Figure 12 represents, change in Carbon monoxide with engine load for various preheating temperatures. Up to around 80% load, there is no significance in CO. After 80% load; there is a very significant increase in smoke was observed. At peak efficiency point, 0.18 by % volume was observed with 900C preheated SVO, which is just double the diesel operation and lesser than all other preheating conditions.

Figure 13. Carbon Dioxide Emissions.

Figure 14. Hydrocarbon Emissions.

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It is observed from Figure 13, a variation of Carbon Dioxide with engine load and preheating temperatures, that CO2 kept on increased with increasing load. At 80% load and 900C preheated temperature 9.5% by volume was registered, which is 1.4% higher than the neat diesel operation and lesser than all other preheating temperatures. Figure 14 depicts the variation of hydrocarbon with different engine loads for different preheating conditions. Up to 80% load, there is no much raise in HC. However, at maximum load exponential rise in HC were observed due to high fuel consumption and its subsequent improper burning. At maximum efficiency point and 900C, 4 ppm was observed, which is 3 ppm higher than neat diesel operation and lesser than all preheating conditions.

CONCLUSION As the crude oil reserves getting diminishing and alarming the environmental pollutions makes the researchers to the thing on all alternative fuels. One such attempt was made as per geographical and economic concern; Jatropha Curcas was chosen for the experimental study for its compatibility with diesel engines as an alternative fuel to diesel. 7.35 kW IDI CI was selected and tested the direct use of selected oil at different preheating temperatures ranging from 400C to 1200C with an increment of 100C was considered. The preheating temperature of 900 C shown better results at par with neat diesel operation.

FUTURE SCOPE Further, fuel injection strategies play an essential role in optimizing the diesel engine operating with preheated Jatropha Straight Vegetable Oil like advancing the injection timing and Injection Pressure. In this direction will

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enhance the engine performance to meet the stringent emission norms for agricultural engines.

ACKNOWLEDGMENTS The author would like to thank the Engines and Biofuels Research Laboratory, UPES, Dehradun for executing the work under Research Project granted from Ministry of New and Renewable Energy (MNRE), New Delhi.

FUNDING AGENCY Ministry of New and Renewable Energy (MNRE), Government of India (GoI), New Delhi for financial sponsoring the Project bearing Project No. MNRE. No. 103/143/NT.

ORCID AND SCOPUS IDS ORCID Scopus

https://orcid.org/0000-0002-5781-4764 57210448403

REFERENCES Demirbaş, A. (2002). “Biodiesel from vegetable oils via transesterification in supercritical methanol.” Energy conversion and management 43(17): 2349-2356. Dunn, R. O. and B. R. Moser (2005). “Cold weather properties and performance of biodiesel.” The biodiesel handbook 30: 83-121.

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Goering E, S. W., Daugherty J, Pryde H, Heakin J (1982). “Fuel properties of eleven vegetable oils.” Transactions of the ASAE 25: 1472–1483. Haile, M. (2014). Biofuel Energy: spent coffee grounds biodiesel, bioethanol and solid fuel, diplom. de. Knothe, G. (2005). The Biodiesel Handbook. 1-302. Knothe, G., Van Gerpen, J., and Krahl, J, AOCS Press, Urbana, IL. Misra, R. and M. Murthy (2010). “Straight vegetable oils usage in a compression ignition engine—A review.” Renewable and Sustainable Energy Reviews 14(9): 3005-3013. PS Ranjit (2014). Studies on Hydrogen Supplementation of SVO Operated IDI CI Engine for Performance Improvement and Reduction in Emissions. PhD, University of Petroleum & Energy Studies. PS Ranjit, N. K., Mukesh Saxena et al., (April 2014). “Studies on various Performance, Combustion & Emission Characteristics of an IDI CI Engine with Multi-hole injector at different Injection Pressures and using SVO-Diesel blend as fuel.” International Journal of Emerging Technology and Advanced Engineering (IJETAE) 4(4): 340-344. Pramanik, K. (2003). “Properties and use of jatropha Curcas oil and diesel fuel blends in compression ignition engine.” Renewable Energy 28(2): 239-248. Pundir, B. P. (2010). IC Engines: Combustion and Emissions. 197. Ramadhas, A., S. Jayaraj and C. Muraleedharan (2004). “Use of vegetable oils as IC engine fuels—a review.” Renewable energy 29(5): 727-742. Ranjit, P. S. and V. Chintala (2020). “Impact of liquid fuel injection timings on gaseous hydrogen supplemented -preheated straight vegetable oil (SVO) operated compression ignition engine.” Energy Sources, Part A: Recovery, Utilization, and Environmental Effects: 122. Vellguth, G. (1983). “Performance of vegetable oils and their monoesters as fuels for diesel engines.” SAE transactions: 1098-1107.

In: Properties and Uses of Vegetable Oils ISBN: 978-1-53619-207-0 Editors: Y. Singh and N. Kr. Singh © 2021 Nova Science Publishers, Inc.

Chapter 10

CASHEW NUT SHELL OIL: A VERSATILE BY-PRODUCT OF CASHEW INDUSTRY Bharat Dholakiya and Smita Jauhari Applied Chemistry Department, Sardar Vallabhbhai National Institute of Technology (SVNIT), Surat, Gujarat, India

ABSTRACT A cashew nut shell oil (CNSO) is a versatile by-product of the cashew industry. The cashew nut has a shell of about 1/8-inch thickness inside which is a soft honeycomb structure containing a dark reddishbrown viscous liquid called cashew nut shell oil, which is the pericarp fluid of the cashew nut. It is often considered as the better and cheaper raw material for the synthesis of various industrially important polymers. CNSO is a renewable and reliable feedstock as a replacement for existing non-renewable petrochemical feedstock. CNSO has innumerable applications in polymer-based industries such as friction linings, paints, and varnishes, laminating resins, rubber compounding resins, cashew cement, polyurethane-based polymers, surfactants, epoxy resins, foundry chemicals and intermediates for the chemical industry. It offers much 

Corresponding Author’s E-mail: [email protected].

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Bharat Dholakiya and Smita Jauhari scope and varied opportunities for the development of tailor-made polymers.

Keywords: cashewnut shell oil, cardanol, phenolic resin, polyurethane

1. INTRODUCTION Cashew (Anacardium occidentale L.), belonging to the family of Anacardiaceae, is an evergreen tree with a dome-shaped canopy (Figure 1.1. (a)). It produces nuts, the kernals of which have increased considerably in economic importance over the past few years. The fruit is a grey, kidney-shaped nut borne on a fleshy, brightly colored pseudocarp popularly known as the apple (Figure 1.1. (b)). A thin testa skin surrounds the kernel and keeps it separated from the inside of the shell. The primary products of cashew nuts are the kernels (Figure 1.1. (c)), which have value as confectionary nuts.

Figure 1.1. (a). Cashew tree, (b). Cashew apple, (c). Cashew nut and (d). CNSO.

The cashew apple, externally attached to the born nut by stem contains the thick vesicant oil, cashew nut shell oil (CNSO), within a sponge-like interior. Cashew nut shell oil (CNSO) (Figure 1.1. (d)), an important

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industrial raw material obtained as a by-product of the cashew industry [1]. It amounts to approximately 67% of the nut. The major components of CNSO are anacardic acid (60–65%), cardol (15–20%), cardanol (10%), and traces of methyl cardol. These mentioned by-products are low cost and amply obtainable to use them as promising renewable resource materials [2-4].

1.1. Versatility of the Cashew Nut Tree (Anacardium occidentale) Anacardium occidentale has great societal and remunerative importance for Asian, African, and Latin American countries [5-6]. It has acquired much attentiveness due to the demand of the kernels in the global market and today it plays a major role in earning enormous foreign exchange for many developing tropical countries. The manual processing of the kernels needs a large workforce and provides a means of securing the necessities of life for the workforce associated with low skill level work, of whom over 95% are women from rural areas in India and Africa [7-8]. CNSO, also known as Anacardium occidentale shell oil, is obtained as a by-product during the kernel isolation. It is a precious feedstock for several polymer-based industries like paints, varnishes, resins, industrial and decorative laminates, brake linings, rubber compounding resins, and casting chemicals [5, 9].

2. CASHEW NUT SHELL OIL 2.1. Introduction CNSO is a resourceful ingredient of the nuts of cashew fruit. It is a natural oil that could serve as a valuable starting material for manifold

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industrial applications. Rapidly increasing global population and standard of living has overstretched petroleum resources as a petrochemical feedstock for various industrial applications. This among other factors has led to the fast depletion of universal petroleum reserves. Therefore, to maintain the standard of living and continuity of the industrial sector which is paramount to human survival in this decade and beyond, there is a need to find alternative sources of fuel and petrochemical feedstock. CNSO, a by-product of the cashew industry, is an important natural and renewable feedstock as a replacement of the petrochemical feedstock for various chemical industries [10].

2.2. Extraction of CNSO from Cashew Nut Shell CNSO, represents about a quarter of the mass of an unshelled nut and equal to that of the kernal, is a source of long-chain m-substituted phenols. CNSO is an excellent monomer for the synthesis of various industrially important polymers. CNSO and their major four components can be obtained as by-products of cashew industries, are low cost and amply available to use them as promising renewable resource materials [11-12]. Many processes are used to extract the CNSO from cashew nut shell. The extraction process is of basic two types: (i). the extraction process that involves heating and (ii). the extraction process that is done in cold or at room temperature. The extraction of CNSO that involves heating can be achieved by open recipients or drums [13]. In the extraction process, the cashews can also be heated by the actual CNSO in a process denominated as thermo–mechanic (hot oil process) [14]. The CNSO extracted under cold condition or at room temperature obtained by extraction, in presence of suitable solvents or by pressing method. The CNSO obtained by the extraction under cold is termed as natural CNSO and when extracted in hot is known as technical CNSO. Natural CNSO contains a higher content of cardol and anacardic acid and a lower percentage of cardanol than technical CNSO. [15-19].

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2.2.1. Hot Oil Bath Method This is the most common commercial way of processing cashew nuts and extracting CNSO. In the extraction process, cashew nut shell is charged in the cylindrical extractor, where steam heating is applied at a temperature around 200-250ºC for 2-3 minutes. During heating with steam, the outer part of the shell burst, open and releases CNSO. About 50% of the oil contained in the nuts is thus obtained. The hot oil bath method makes the easy putrefaction of nuts, without adversely affecting the quality of the cashew kernels and CNSO. The extraction efficiency of the method was improved by initial surface wetting and dipping in the water at 2025oC and subsequent steam treatment prior to exposure to the hot CNSO bath. As a result of surface wetting and dipping, 7-10% moisture of the weight of the nuts increases, and it causes the cells to burst, with the result that the CNSO exudes into the bath. Another 20% oil could be recovered from spent shells by the expeller method and the rest percentage of CNSO by a solvent extraction method. The CNSO obtained by expeller method can be reformed by acid washing followed by centrifugation and heating [20]. 2.2.2. Roasting Method In the traditional manual roasting method, the nuts are roasted in a perforated open pan over a wood fire. Before the roast, the nuts are usually soaked in water to avoid scorching. During roasting, the nuts swell, and the CNSO containing cells burst, ejecting the resinous liquid which drips through holes of the pan. The shells are charred during this process, producing an explosive pressure in the cellular structure, which forces the liquid out of the shell. In drum roasting, the nuts are heated at high temperature in a rotating drum and then shelled. One variation of this method is abrading at 100-300°C for about 1hr and subsequent roasting at 400-700°C in an inert atmosphere. This method is used in concomitance with an expeller method, where the CNSO is expelled from the cashew shells to an extent of 90% [21].

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2.2.3. Screw Pressing Method The CNSO from cashew nut shell is generally extracted by three methods namely, mechanical, roasting, and solvent extraction. The screw pressing (mechanical) process of CNSO extraction is more feasible for adoption on an industrial scale. The raw cashew nut shells are charged in the hydraulic press or screw press and then applied high pressure to extract CNSO from the shell. This method is straight forward and fast among others. Extraction of CNSO by screw press method is reported by using tapered compression screw, feeding rollers of transversal zigzag surface type, and cylindrical casing with 2 mm diameter holes. By using a screw speed of 7-13 rpm and a feeding rate of 54-95 kg/hr, the percentage of CNSO extracted was 20.65-21.04%. However, the spent shell from this method still carries 10 to 15% of CNSO. The CNSO obtained by this method contains 42% cardol, 47% anacardic acid, and 3% cardanol [22]. The CNSO was also extracted by varying the moisture content of shells. Pressure and feed rate were maintained constant throughout the tests of oil extraction. The moisture content of the cashew nut shells at the time of extraction of CNSO has a great influence on the oil recovery. It is found that 10.06% moisture content in cashew nut shells is the optimum moisture content for the extraction of CNSO from cashew nut shells to get the maximum oil recovery of 86.68%. 2.2.4. Solvent Extraction Method The CNSO from shells of cashew nut is extracted by different methods but solvent extraction is more industrial viable and efficient method among others. This extraction method gives off most of the CNSO compared to other extraction methods. The residual CNSO in the cake is less than 1% by weight. For extraction through the solvent method, pretreated cashew nut shell is reduced to a small size to ease the extraction. The suitable organic solvent is used to extract CNSO from the cashew nut shell. The solution containing CNSO is separated from the solid particles and distilled to boil off the added solvent, which is subsequently condensed for recycle in the extraction process [23].

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2.3. Chemical Composition of Cashew Nut Shell Oil CNSO is said to be the most widely distributed and abundant natural phenolic lipid source. The phenolic lipids present in CNSO are: (i) phenolic acid:-anacardic acid [24-25] (ii) dihydric phenol:- cardol [24, 26] (iii) monohydric phenol:-cardanol [27] and (iv) 2-methyl cardol [28]. Figure 2.1 shows the components of CNSO [29]. Anacardic acid is the major component of natural CNSO but during the hot oil bath process, it gets decarboxylated to cardanol. Cardanol is the minor component of natural CNSO and the major one in technical CNSO [30]. Natural CNSO is a cold-press extracted oil from a cashew nut shell. It contains approximately 70% of anacardic acid, 18% of cardol, 5% of cardanol, and 2% of 2-methyl cardanol. Anacardic acid and cardanol are monohydroxy phenols. Cardol and methyl cardanol are dihydroxy phenols. Technical CNSO has innumerable applications in polymer-based industries such as friction linings, paints, and varnishes, laminating resins, rubber compounding resins, cashew cement, polyurethane-based polymers, surfactants, epoxy resins, foundry chemicals and intermediates for the chemical industry.

Figure 2.1. Main components of CNSO.

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2.4. Isolation of Major Components of Cashew Nut Shell Oil CNSO and its derivatives are extensively used in polymer-based industries, in the synthesis of other industrially important chemicals and intermediates including surface-active agents, bactericides, and insecticides. CNSO contains phenolic constituents such as anacardic acid, cardanol, and cardol. Cardanol holds the phenolic group and polymerizable side chain. Cardanol and its derivatives have found several industrial applications [31]. Stadeler in 1847, first investigated CNSO systematically and separated cardol from anacardic acid and decarboxylated anacardic acid [24]. But the correct formula for the acid, C22H32O3 (this is the molecular formula for the diene which is the average unsaturation) was not established till 40 years [32]. Tyman et al. synthesized anacardic acid by two different methods [33]. A.J.H. Smit, in 1931 recognized the presence of salicylic acid system and a penta decadienyl side chain [34] and P. Von Rornburg put forward the structure of anacardic acid and anacardol (Figure 2.2.) (the name anacardol was used for cardanol in the early years but changed into cardanol by M.T. Harvey) [35].

Figure: 2.2. Structure of anacardic acid and anacardol.

2.4.1. Isolation of Anacardic Acid from Cashew Nut Shell Oil The CNSO and their phenolic components are hydrophobic, and the aqueous solvents system is not useful for their separations. General Foods

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Corporation (Rye, NY) was the first to report a method to isolate anacardic acid as alkaline earth metal salt [36]. Although this method is efficient, the purity of the product was not supported by any modern chromatographic or spectral data. Later, the effort was made to isolate anacardic acid by making a sodium salt which is stable at ambient temperature. Some researchers have reported sodium salt treatment with solvent to remove non-acid compounds and treatment with acid to obtained crude anacardic acid. The resulted product was very low in yield. This method was modified by acid precipitation from an alcoholic solution with freshly lead hydroxide solution [28]. This process's demerit is the ammonium salt of acid was so sticky and viscous to filter it from the fine suspension of lead sulfide. To overcome this problem, the process was modified by using lead salt in an ethereal solution [37]. Ethereal salt with lead anacardate was continuously stirred at room temperature with diluted HCl followed by water. Finally, the solution was distilled to obtained anacardic acid. Fatty acid esters and anacardic acid were separated from methylation using silica gel by Gellerrnam et.al. The separation of anacardic acid from other phenolic compounds of CNSO with diazomethane under ambient conditions is also reported [38]. Column chromatographic techniques can also be used for the isolation of anacardic acid from CNSO. In this process, CNSO is portioned with water and hexane. The components were eluted with ethyl acetate-hexane-acetic acid (10: 90:1 to 20:80:1 v/v) and further separated into phenols using the HPLC technique [39]. As anacardic acid is a more acidic compound, it forms a salt with weakly alkaline amines. Whereas cardol and cardanol being phenolic components and weakly acidic, are unretained on weakly alkaline surfaces. Anacardic acid was separated by preparing slurry from 500 gm of feed in 1500 ml of hexane with 30 ml of triethylamine, and 100 ml of hexane was loaded into silica gel column by using a separating funnel as the delivery system. The silica gel column was soaked with 4000 ml of ethyl acetate and hexane mixture in the ratio of (25:75v/v) containing 1% acetic acid. The evaporation of effluent from the column yielded 70 gm of anacardic acid. Among various bases like ammonia, primary amine, tertiary amine,

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and an aromatic amine, triethylamine was found to be a more effective base for separating anacardic acid from CNSO. The anacardic acid contains saturated anacardic acid, mono, di, and tri olefins. These four components of anacardic acid were separated using low-temperature crystallization in the temperature range of 0 to 80°C [40]. Nagabhushana et al. did isolation of anacardic acid from CNSO by using a column chromatography technique. In this method, 100 gm CNSO was loaded into a silica gel bed with a solvent system consisting of ethyl acetate-hexane (25:75) and 0.5% triethylamine, and finally, a higher amount of acidic compound obtained, which is confirmed by HPLC [41]. Work was also reported for isolation of anacardic acid by ion-exchange resin using organic solvents as a mobile phase. This method is not industrially viable for the separation of anacardic acid from CNSO because the use of non-aqueous solvent affects the life of ion-exchange resins [42]. Tyman et al. used carbon tetrachloride to extract cashew nut shell oil (400 g). It was found that CNSO 91.08 g, (32.6%) was recovered and purified by lead salt precipitation, filtration, and regeneration with cold dilute nitric acid. The anacardic acid was obtained as a viscous brown liquid 26.68 g (29.3%) [17]. The extraction of CNSO from the shell by solvent extraction using carbon tetrachloride as a solvent for 6 hr has been reported. The final yield of CNSO obtained was 145.7 gm, 29.1%. Ancardic acid was also isolated as a lead anacardate using the precipitation method. The lead anacardate was dried and treated with HCl to release free anacardic acid with a yield of 84.1 gm, 58% [43].

2.4.2. Isolation of Cardanol and Cardol Cardanol is a phenolic lipid obtained from CNSO, a byproduct of the cashew industry. It is a tenable and low-cost aromatic bio-monomer available as agricultural waste in major parts of the world for various industrial applications. The cardanol is a phenol-based monomer with a meta-substituted unsaturated alkyl side chain containing fifteen carbons and has different functionalization sites. Considering the difficulty of synthesizing phenols with a long unsaturated carbon chain at metaposition, cardanol is a precious starting material for synthesizing different

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types of resins due to low price and abundance availability [44]. Cardanol is obtained from the distillation of technical CNSO under reduced pressure as a mixture of cardanol 90% and cardol 10%. The commercial cardanol differs in the degree of unsaturation of the side chain. The average unsaturation of two double bonds in the side chain of the cardanol makes cross-linking easy. It provides satisfactory gradual drying and baking properties to paints and chemicals prepared from it. Because of its unique structure, varnishes prepared from cardanol have high electric insulation, greater water resistance, chemicals, and good flexibility. The cardanol's significant advantage is its amenability to the chemical modification to obtain desirable structural changes to get specific properties for preparing tailor-made polymers of high value. Thus, structural changes can be made at the hydroxyl group, the aromatic ring, and the unsaturated alkyl side chain. The distinctive molecular structure of cardanol, especially the unsaturation of long unsaturated hydrocarbon side chain, makes the crosslinking easy during the polymerization. Cardanol is an ideal monomer for polymer preparation for the coating industry due to its unique structure and excellent properties. It is widely used to manufacture curing agents for epoxy and other resins. Cardanol is extensively used in the manufacture of rubber, adhesives, pesticides, mineral oils, electrical isolation putty, printing ink, and brake linings. Cardanol contributes to good drying after baking, improved flexibility, high electric insulation properties, and thermal stability. These unique properties make cardanol an effective renewable bio-substitute for the petroleum-based phenol. The products manufactured from cardanol have many advantages over petrochemicalbased substituted phenols. Therefore it is widely used in the manufacture of surface coating materials, insulating varnishes, resins, rubber compounds, azo dyes, etc. CNSO was separated into cardanol, cardol using column chromatography, to recover cardanol, which is to be further utilized to synthesize cation exchange resins. In the separation process, the mobile phase is a racemic mixture of benzene and chloroform, and the stationary phase is a column packed with silica gel adsorbent of particle size 60-120 mesh as the stationary phase. A paste was prepared by mixing 80 ml of

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CNSO, 60 ml of chloroform, and 170 gm of silica and dried at 100°C for 3 hr. During drying of CNSO paste, anacardic acid gets converted into cardanol by decarboxylation, and the resultant product is known as technical CNSO. The mean RF value of cardanol was 0.516, for cardol, it was 0.173, and for 2-methyl cardol, it was 0.148. The pH of CNSO and cardanol was 6.69 and 3.43, respectively, suggesting cardanol is more acidic than CNSO. The pH value also suggested the presence of less amount of anacardic acid in the CNSO. Technical CNSO (100 gm) was dissolved in methanol (320 ml), and ammonium hydroxide (25%, 200 ml) was added and stirred for 15 min. This solution obtained was extracted with hexane (4×200 ml). 5% HCl (100 ml), the wash was given to the organic layer, followed by distilled water (100 ml). Activated charcoal (10 gm) was added to the organic layer, stirred for 10 min, and filtered through Celite (15 gm). The filtrate obtained was dried over anhydrous sodium sulfate and concentrated to get pure cardanol (65 gm). The methanolic ammonia solution was extracted with ethyl acetate/hexane (4:1) (2×200 ml). The organic layer obtained was washed with 5% HCl (100 ml) followed by distilled water (100 ml), which was dried over anhydrous sodium sulfate, and concentrated to yield pure cardol (20 g). The purity of cardanol and cardol was confirmed by HPLC [40].

2.4.3. Direct Separation of Cardanol from Cashew Nut Shell Oil by Decarboxylation Process Cardanol can be obtained from CNSO using the direct separation process by decarboxylation of anacardic acid. In the decarboxylation process, CNSO (100 g) was refluxed with toluene (150 ml) as a refluxing solvent for 3 hr by using a dean-stark apparatus to obtain decarboxylated CNSO. Now decarboxylated CNSO (50 gm) was refluxed for 2 hr with 200 ml methanol, 20 ml of 40% formaldehyde solution, and 3.0 ml diethylenetriamine in the round bottom flask. The solution was cooled to room temperature after reflux and settled for phase separation, showing a slightly reddish upper layer and a dark brown solidified lower layer. The upper layer was subsequently decanted and treated with distilled water (40 ml), followed by treatment with petroleum ether. The petroleum ether layer

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was evaporated to dryness, giving a reddish residue as cardanol (26 gm) (Figure 2.3.) [31, 45-46].

Figure 2.3. Conversion of anacardic acid to cardanol by decarboxylation.

2.5. Present and Future Trends of Cashew Nut Shell Oil Although Anacardium occidentale is native to Central America, the Caribbean Islands, and northern South America, including northeastern Brazil, the species is already promulgated in many countries worldwide, especially in India, Viet Nam, Cote d’Ivoire, Nigeria, Philippines, Tanzania, Guinea-Bissau, and Indonesia. Portuguese colonists in Brazil began exporting cashew nuts as early as the 1550s. In 2017, Vietnam, India, and Ivory Coast were the major producers of cashew nuts due to similar climate conditions. From a commercial point of view, the global production of cashew nut is growing every year, along with the area of plantation. According to the Food and Agriculture Organization of the United Nations [47], the global annual production of cashew nut (with shell) increased more than 400% times, and the amount increased from 1.053.232 tonnes to 4.439.960 tonnes per year considering the period of 20 years from 1993 to 2013. In the same period, the total land harvested for cashew production increased from 2.089.710 ha to 5.457.009 ha per year, a growing around 260% times. In this period, the top 5 producers of cashews

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were Brazil, Côte D’Ivoire, India, Nigeria, and VietNam in increasing order. These countries were responsible for producing around 75% of the global production of cashews [47]. Considering these numbers for the global production of cashews and the fact that CNSO contains around 25% of the total weight of cashew nut, one can estimate that, only in 2013, about 1.000.000 tonnes of CNSO were obtained as a by-product from the cashew nut processing [48]. The global cashew nut shell oil market is surging owing to frequent innovations and the development of renewable and biodegradable cashew nutshell oil-based products. The global cashew nut shell oil market is expected to grow in the Asia Pacific, especially in India, due to the presence of key market players in the region and the export of CNSO in other countries. The report on the global cashew nut shell oil market gives historical, current, and future market sizes (US$ 517.41 Mn) based on product types, application, and regions such as North America, Europe, Asia Pacific, Latin America, Middle East and Africa. The CNSO market is expected to reach US$ 517.41 Mn by 2025 and is poised to grow at a significant compound annual growth rate (CAGR) over 2019-2025.

3. APPLICATION AND USES OF CASHEW NUT SHELL OIL CNSO has numerous industrial applications like manufacturing of polyurethane, surfactants, epoxy, other tailor-made polymers, acid-resistant paints and varnishes, insecticides and fungicides, lacquers, bakelite, and enamels. The main applications of CNSO are in the polymer industry [45, 49]. Polymers synthesized from CNSO have certain exceptional properties that make them unique for many industrial applications. The most attractive feature of CNSO as a raw material is its cost-effectiveness and versatility. The polymer derived from CNSO shows good flexibility and water resistance due to internal plasticization resulting from a long alkyl side chain. The polymer prepared from CNSO has low fade characteristics, which makes it a preferable component in brake lining formulation. CNSO

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based resins possess outstanding resistance to mineral oils' softening action and high resistance to acids and alkalis [50]. CNSO based polymers also have useful characteristics such as heat and electrical resistance, antimicrobial properties, and termite and insect resistance [51]. The CNSO and its components show excellent biological activities such as antitumor [52], antioxidant [53], and antibiotic [54]. Polymers and resin prepared from CNSO have vast industrial applications such as surface coating, friction materials, laminates, adhesives, anticorrosive paints, rubber compounding, and flame retardants [55]. CNSO was also recently studied as rubber plasticizers [56], in polyurethanes synthesis [57], in the cure of epoxy resin [58], and the phenol-formaldehyde resin synthesis [59]. The solubility of CNSO in the number of common solvents makes it a natural choice for the number of surface coating applications. CNSO and its derivates show antioxidative properties [60]. The quaternary nitrogen compounds derived from the mono-phenolic components of CNSO are soluble in water, very stable, odorless, possess high antibacterial activity, and act as surface-active agents [61]. The sodium anacardate is used as anionic surface-active agents [62-68], and disodium anacardate could be a useful bactericidal surfactant. CNSO reduced the rate of corrosion taking place on the carbon steel surface. The corrosion rate of the carbon steel surface was decreased by over 90% with just 300 ppm of CNSO under stationary conditions. CNSO is an outstanding corrosion inhibitor for carbon steel in a CO2 medium, and it has been found to have better performance at a very low concentration under dynamic conditions. High inhibitor performance of about 96% was observed with just the addition of 20 ppm of CNSO. Furthermore, the results also revealed that CNSO as corrosion inhibitor is temperature-sensitive. The performance of CNSO as a corrosion inhibitor decreases with an increase in temperature and works more efficiently at ambient temperature [66]. The anti-corrosive paint formulations prepared from CNSO for ship bottoms have been widely reported [67-68]. Coatings with various colors can be prepared using CNSO by oxidizing it with HNO3 that air-dry very quickly and are suitable for making paints, varnishes, electrical insulation, impregnating paper, woven fabrics, etc.

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CNSO based coated papers for bottle caps have been developed and cured at 150°C for 10 min [69]. CNSO is also used in the formulation of electropainting compositions [70]. Various materials such as bauxite residue, kaolin, zinc chromates, barium, manganese, lead silico-chromates, and mica have been added to CNSO based formulations as fillers. Some of these formulations showed enhanced corrosion resistance [71]. Cement prepared by mixing of cardanol formaldehyde resin dissolved in solvents with portland cement with setting time 6 hr at room temperature having very good resistance to water, oil, and heat. This formulation can also be used as paint. Water impermeable coating materials for walls of cement, wood, fabric, etc., were formulated by reacting CNSO with alkaline materials such as cement, alumina, barium hydroxide, sodium carbonate, etc. Water-soluble resin for electrodepositing on mild steel was prepared by treating CNSO with formaldehyde using alkali catalyst [72]. Air drying corrosion-resistant resin for coating application was prepared by the reaction of bisphenol epoxy resins with CNSO and unsaturated fatty acids [73]. Surface coating formulations for the preservation of concrete against attack by chemical fertilizers have been developed from CNSO. Coating material giving tough elastic films were formulated from CNSO–glycerin reaction products [74]. CNSO is also used for making diesel oil [75]. The incorporation of CNSO has been found to improve the processing and vulcanized rubber products' vulcanized properties [76]. The resin obtained by reaction of styrene and CNSO has been used as plasticizers for rubbers to improve fillers' intake. CNSO is also used in the preparation of vibration-absorbing rubber material. Tyre rubber compositions with good processibility and hardness were developed from modified CNSO. The use of CNSO increases the insolubility of nature rubber vulcanizates in petroleum solvents and acts as an antioxidant in natural rubber vulcanizes [77]. Compounding of less than 10% cardanol with natural rubber reduces viscosity and improves abrasion resistance, tensile strength, and aging properties [78-79]. CNSO-HCHO resin is used in the preparation of cutting pads for leather from natural rubber. Products obtained from acid polymerized CNSO and hexamine are millable materials that serve as a

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natural rubber plasticizer. The processability characteristics of the natural rubber-halogenated CNSO polymer system have been studied [80]. Highperformance and specialty polymers can be produced from cardanol by different synthetic routes [81]. Fire resistance pre-polymers were obtained from cardanol by simultaneous phosphorylation and oligomerization. The effect of substitution of phenol by CNSO on the properties of novolac and resole resins has been experimentally investigated [82]. The composite panels suitable for partitions, flush doors, cladding, etc., can be made using CNSO-HCHO resins [83]. Lightweight foam plastics were developed from CNSO are found to become lighter upon aging for 12 days at 100°C [84]. The effect of the addition of cardanol on peroxide curing of polyester resin has also been studied [85]. Phosphorylated CNSO enhances the thermal stability of lowdensity polyethylene [86]. A water resistance resin composition was prepared from CNSO by heating CNSO with shellac at 100°C. A heatresistant resin can be obtained from CNSO using phase transfer catalyst or when it is polymerized with TiCl4 or ZnCl4 in the presence of a Grignard reagent in an inert atmosphere. CNSO can be used to make a sustrative fiber reinforced polymer by incorporating bromine into the phosphorylated prepolymer [87]. The resins suitable for electrical insulations can be obtained by reacting CNSO with fatty acids and glycerin. The epoxy derivative of CNSO can be used as a PVC stabilizer [88]. The rate of dehydrochlorination of PVC can be reduced by using CNSO [89]. Sulfurated CNSO is used as a plasticizer [90], and cardanol condensed with epichlorohydrin is used as a stabilizer [91] for PVC. The low and high-temperature performance of asphalt can be improved using CNSO as a chemical modifier [92]. Resins prepared from polymerized CNSO and furfural are suitable for insulation parts for storage batteries because of their resistance to acids and alkalies. The reaction product of CNSO and diethylenetriamine is used as a curing agent for epoxy resins. CNSO, its polymeric products, and chemical derivatives find various applications in the industry [87-93].

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4. PROPERTIES OF CASHEW NUT SHELL OIL The Anacardium occidentale is a tropical evergreen tree that produces the cashew seed, cashew apple, and oil. It produces two “oils,” one of which is found between the seed coat and the nuts, is called the CNSO. CNSO is not a triglyceride and but it contains a high proportion of natural phenolic lipid compounds. It is toxic and corrosive to the skin [94]. Another oil is an edible oil that can be extracted from cashew nuts. CNSO is a low-cost, versatile phenol for polymerization and chemical modification for the development of high-performance polymers. Chaudhari et al. reported three main properties of cashew nut oil are specific gravity, viscosity, and moisture content [95]. Evbuowman et al. reported the chemical and physical properties of CNSO [96]. The physicochemical characteristics of CNSO from two varieties, Table 4.1 shows Brazilian (BRZ) and African species (AFR) of cashew nut shells The CNSO from the two different varieties of cashew nut shells is dark brown. The refractive index of the CNSO of BRZ and AFR species was 1.693 and 1.686, respectively, and specific gravities were 0.941 and 0.924, respectively, which indicate that they are both less dense than water. CNSO obtained from BRZ and AFR varieties were viscous with viscosity values at 56 and 41 centipoise (CP) and moisture content was 3.9% and 6.7% respectively. The low moisture content is an indication that the oils can have a longer shelflife. The ash content is 1.2% and 1.3% for BRZ and AFR, respectively. The saponification value of both samples is low; 58.1 mg KOH/g and 47.6 mg KOH/g, respectively. The iodine value is high 215mg iodine/100g and 235mg iodine/100g, respectively, which fell within the range of 220-270 mg iodine/100g specified as drying oils. The high iodine value of CNSO obtained from BRZ and AFR species is an indication that the oil contained a high degree of unsaturation. Due to a high degree of unsaturation, it can be used as a drying oil and find applications in paints, varnishes, and surface coatings, etc. The acid value is 6.1 mg KOH/g and 7.8 mg KOH/g for BRZ and AFR varieties, respectively. CNSO is, therefore, not an edible oil [94].

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5. SYNTHESIS AND CHARACTERIZATION OF RIGID POLYURETHANE FOAM FROM CASHEW NUT SHELL OIL 5.1. Introduction Polyurethane (PU) is the polymer containing a significant number of urethane groups (-NH-CO-O) in the polymer's backbone chain. The discovery of PU dates back to the year 1937 by Otto Bayer and his coworkers at the laboratories of I.G. Farben in Leverkusen, Germany [97]. The underpinning of the PU industry was laid in the late 1930s. The first commercial application of PU polymer for coatings, millable elastomers, and adhesives was developed between 1945 and 1947, and then flexible foams in 1953 and rigid foams in 1957 [98]. The growth of the polyurethane was constant, and the future's prediction is very optimistic due to the new markets opened in Eastern Europe, Asia, and South America [99]. The main application of PU polymer is in the furniture industry to produce mattresses from flexible foams and the automotive industry to manufacture seat cushioning, bumpers, and sound insulation from flexible and semi-flexible foams. Rigid polyurethane foams are used in the thermal insulation of buildings and refrigerators, pipe insulation, cold stores, refrigerated transport, thermal insulation in chemical and food industries. The polyurethane elastomers are used for footwear, shoe soles, athletic shoes, pipe linings, pumps, tyres, microcellular elastomers, etc. Polyurethane is also used as sealants, adhesives, coatings, and fibers. Approximately 64% of the total global production of PU is used in the formulation of rigid and flexible foams [100-102]. Table 5.1. shows properties of polyol used for rigid and flexible polyurethane foam. Table 5.1. Properties of polyol for rigid and flexible polyurethane foam PU Application Flexible Foams Semi-rigid foams Rigid Foams

Functionality of polyols 2-3 3-5 3-8

Hydroxyl value mg of KOH/g 28-160 140-350 70-800

Molecular weight 2000-10000 1500-6500 200-1000

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The flexible polyurethane is prepared using high molecular weight polyols, which have lower functionality of around 2-3 hydroxyl groups/mol [103-105]. The rigid polyurethane is prepared using low molecular weight polyols, which have high functionalities of around 3-8 hydroxyl groups/mol. Rigid polyurethane foam is obtained by reacting low molecular weight polyols of high functionality with diisocyanate or polyisocyanate (having 2-3 NCO groups/mol) [106-107]. The preparation of isocyanate based foam is a simultaneous occurrence of polymer formation and gas generation. Foams are prepared by mixing component A (a blend of polyol, catalyst, and surfactant) and component B (isocyanate) at room temperature. The foaming system can be divided into three kinds of systems: (i) Prepolymer system, (ii) A quasi-prepolymer system, and (iii). One-step system [108-110]. Prepolymer system is often used to formulate polyurethane coatings, elastomers, flexible foams, sealants, etc. The Quasi-prepolymer system is usually used to transmute a solid isocyanate into a liquid and is used to prepare flexible PU foams, microcellular elastomers, and other PU applications. The one-step system and the quasi-prepolymer system are presently used in the polyurethane foam industry, in which the one-step process has become the main process for both flexible and rigid foam formulations.

5.2. Raw Materials for Polyurethane Foam The basic raw materials for making polyurethane foams are isocyanates and polyols.

5.2.1. Isocyanates The isocyanates are a family of highly reactive, low molecular weight compounds widely used in the manufacture of flexible and rigid foams, fibers, coatings such as paints and varnishes, elastomers and are increasingly used in the automobile industry, autobody repair, and building insulation materials. Spray-on polyurethane products containing isocyanates have been developed for a wide range of retail, commercial,

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and industrial uses to protect cement, wood, fiberglass, steel, and aluminum, including protective coatings for truck beds, trailers, boats, foundations, and decks. The important isocyanates for most polyurethane applications are aromatic isocyanates: diphenylmethane diisocyanate (MDI) and toluene diisocyanate (TDI). Aliphatic isocyanates such as isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), or 4,4' Methylene-bis (cyclohexyl isocyanate) (HMDI) are used only for special applications. Aromatic polyisocyanate has been used for the preparation of isocyanate based foams. Aliphatic isocyanates were not used because foaming reactions require high reactivity, and aliphatic polyisocyanate reacts slowly with OH groups [111-112].

5.2.2. Polyols Polyols are generally synthesized by one of two possible chemical routes, namely alkoxylation and esterification. By far the most common route, alkoxylation involves the reaction between a hydroxyl or aminecontaining initiator (such as sucrose, glycerol, ethylene diamine, etc.) and either propylene or ethylene oxide. This reaction, which is carried out at elevated temperature and pressure, can be tailored to add varying amounts of the alkoxylating species to modify the polyol chain length or molecular weight. In this manner, low molecular weight polyols can be produced for rigid foams, having molecular weights ranging from 200 to 1000. By extending the polymer chain with a higher level of alkylene oxide, a molecular weight of up to 6000 can be obtained. This latter product is suitable for more flexible polyurethanes in cushioning and elastomeric applications. The second essential component in PU synthesis is a polyol. The chemical structure of these compounds has an intense effect on the properties of the final PU polymers. These compounds have a hydroxyl group that can react with a diisocyanate, which enables the preparation of various types of PU. Structurally, polyols are divided into two main categories: polyether polyols (manufactured by the reaction of an epoxyfunctional group-containing starting material with a reactive hydrogencontaining starter or initiator) and polyester polyols (prepared by the

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polycondensation of two and/or multifunctional carboxylic acids and polyhydroxyl compounds or alcohols) [113]. Most of the polyols used currently in the manufacture of polyurethane are derived from the petroleum industry. Polyols derived from rapidly depleting petroleum resources are non-renewable and cause serious environmental problems by releasing CO2 and contributes to global warming. These problems can be solved by preparing bio-based polyols from vegetable oils. The green chemistry initiative since its inception has evolved many active programs to make bio-based polyols from renewable materials like vegetable oils. The usefulness of natural bio-based monomers and polymers, in-lieu of its structural diversity and complexity, to produce high-value polymers after the appropriate chemical modification has been demonstrated [114-116]. Polyurethanes prepared from vegetable oil-based polyols have been reported in the literature [117-118]. Some industrially important polymers prepared from sustainable feedstock like rubber seed oil, CNSO, etc., have also been explored [119-121]. The synthesis of Mannich polyols from cardanol of CNSO to develop rigid polyurethane foams has been recently reported [122]. Polyol prepared by peracid oxidation of cardanol has been successfully used for the preparation of rigid polyurethane foams [123].

5.3. Rigid Polyurethane Foams from Cashew Nut Shell Oil Renewable and environment-friendly agrarian materials are acquiring increasing attention of many researchers because of growing environmental awareness and their potential to replace existing petroleumbased feedstocks. Cardanol, a phenolic constituent of CNSO, is a renewable feedstock of immense potential. The polyurethane (PU) polymer synthesized from cardanol based polyols shows superior mechanical, chemical, and thermal characteristics [124-127]. The polyols prepared from cardanol have better hydrolytic stability than triglyceride-based polyols, and PU exhibited outstanding thermal stability. Cardanol based mannich polyols can be prepared by reacting cardanol with formaldehyde

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and aliphatic amines like ethylene diamine, diethylene triamine, and triethylenetetramine. Rigid polyurethane foam formulated from cardanolbased mannich polyols has excellent physicochemical, mechanical, and fireproofing properties [128]. Tejas et al. have described the step-wise synthesis of Mannich polyols from cardanol, and the resultant polyols were used for rigid PU foam [129]. Rigid PU foams were successfully prepared from Mannich polyols with superior thermal, mechanical, and fire resistance properties. The foaming characteristics were studied [130]. Ethylene oxide was prepared by the reaction between chloroethanol and potassium hydroxide at ambient temperature for 1 hr in the mole ratio 1:1 (Figure 5.1.). The resulting ethylene oxide was absorbed in a methanol solvent [39].

Figure 5.1. Synthesis of ethylene oxide.

Figure 5.2. Synthesis of Mannich precursor [130].

Mannich precursor was synthesized by reacting paraformaldehyde with bis(hydroxyethyl)amine in the molar ratio of 1:1 (Figure 5.2.). The condensation reaction was performed between bis(hydroxyethyl)amine and paraformaldehyde at 50oC for 2 hours, followed by the removal of water through distillation formed during the reaction. The resultant intermediate product is a light yellow liquid and used for the synthesis of Mannich bases [130]. Mannich bases were synthesized by reacting cardanol and Mannich

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precursor in the molar ratio of 1:1 at 70oC for 2.5 hr as shown in figure 5.3. The resultant product was viscous, brown amber liquid [130].

Figure 5.3. Synthesis of Mannich bases [130].

Mannich bio-polyols from cardanol were synthesized by the reaction of Mannich bases and methanolic solution of ethylene oxide in the mole ratio 1:2 at 100oC under autogenous pressure in an autoclave for 3 hr. The polyol synthesis is a self catalyzed reaction by the tertiary nitrogen present in the Mannich base [130] (Figure 5.4.). FTIR and 1HNMR confirmed the structure of Mannich polyols. The molecular weight of Mannich polyols was measured by GPC. Figure 5.5 shows the IR spectra of the Mannich polyol synthesized from Mannich base and ethylene oxide. The broad absorption band observed at around 3367cm-1 confirmed the presence of the hydroxyl (–OH) group. The aliphatic and aromatic C-H stretchings were attributed to sharp bands at 3009, 2923, and 2852 cm-1. Aromatic CC bonds can be confirmed by absorption band at 1585 cm-1, sharp transmission band at 1454 cm-1 shows the presence of C-N linkages in the structure, and band at 1270 cm-1 shows -C-O-C- linkage. The structure of Mannich polyols was further confirmed by the 1HNMR (Figure 5.6.). Peaks at 7.03-6.52 δppm are due to aromatic protons, peak at 5.29 δppm is due to vinyl unsaturation and 3.74-2.48 δppm is due to alkyl unsaturation, hydroxyl groups from the polyol was confirmed by the signal obtained at

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2.03-1.55 δppm and peaks at 1.41-1.27 δppm is due to alkyl and at 0.90 δppm due to -CH3 protons. The number average (Mn) and weight average (Mw) molecular weight were measured by the GPC (Figure 5.7.), synthesized cardanol-based Mannich polyols having number average (Mn) 212.7 and weight average (Mw) 672.9 which indicate its suitable for preparation of rigid PU foam.

Figure 5.4. Syntheis of Mannich Polyols [130].

Polyurethane foam (PUF) was formed by using polyols and isocyanates for chemical structure, equivalent weight, and functionality. Foam properties are affected by the properties of raw materials and can be altered by modifiers. The furniture industry, heat-insulation systems, building construction, transportation (including automotive), the shoe industry, and aviation use PUF. Unlike flexible foams, rigid PUF consists of a high percentage of closed cells. Rigid PUF has a low density (25–150 kg/m3), so a small amount of it occupies large spaces [131]. The one-step system was used to prepare rigid PUF by mixing component A (Mannich polyol, catalyst, fillers, surfactant, blowing agent, etc.) and component B (isocyanate) at room temperature. The components used in rigid PUF formulation is shown in Table 5.2.

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Figure 5.5. IR spectra of Mannich polyols [130].

Figure 5.6. 1H-NMR spectra of Mannich polyols [130].

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Figure 5.7. GPC chromatogram of Mannich polyols [130].

Table 5.2. Components of rigid PUF formulation [130] Components Mannich Polyol (M.W.-672.9) Fillers: Fly ash, Ceramic, Teflon, Sb2O3, PVC Dimethylaminoethanol Silicon B-8404 Castor oil Water Polymeric MDI

Parts by Weight 11 10% 0.19 0.33 21 0.33 Index 110

For PU foam formulation, component A was prepared by mixing cardanol-based Mannich polyol with castor oil, catalysts, filler, surfactant, and blowing agent at 1200 rpm for 10-15 sec. Component B (Polymeric MDI) was added to component A under continuous stirring to prepare a uniform mixture of components A & B. The uniform mixture of components A and B was poured immediately into Teflon mold, and the PU foam was allowed to rise and set at ambient conditions. Mannich polyols prepared from cardanol of CNSO are very reactive due to the presence of the tertiary nitrogen in the structure, exerting a strong catalytic effect in the reaction between hydroxyl and isocyanate groups. A bio-based

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cashew Mannich polyol was successfully synthesized and used to prepare rigid PU foam with a variety of fillers like Teflon, ceramic, fly ash, PVC, and Sb2O3. The resultant PU foam was also studied for kinetic parameters, density, flexural strength, impact strength, morphology, thermogravimetric analysis, and limiting oxygen index. Kinetic study of the rigid PU foam formation includes cream time, rise time, and tack-free time [132-133]. The cream time is a measure of the beginning of the foam reaction, usually characterized by a change in the liquid color as it begins to rise. Rise time is the time when freely rising foam stops growing. Tack free time is the time between the beginning of the foam pour and the point at which the foam's outer skin loses its stickiness. Cream time, rise time, and tack-free time gradually increases during the foaming process by the addition of 10% fillers viz: fly ash, ceramic, Teflon, Sb2O3, and PVC, respectively, as shown in table 5.3. Table 5.3. Kinetic parameters, density, impact and flexural strength and LOI value [130] SN

Fillers (10%)

1 2 3 4 5

Fly Ash Ceramic Teflon Sb2O3 PVC

Kinetic Parameters (Sec) Cream Rise Tack Free Time Time Time 4 62 110 8 74 124 9 92 145 11 112 194 12 128 201

Density (kg/m3) 125.18 134.07 140.74 144.44 148.14

Impact strength (J/m) 11.50 13.30 15.00 15.30 18.53

Flexural strength (N) 6.73 8.94 9.94 11.43 13.95

LOI Value (%) 20.35 20.99 21.10 21.35 22.86

The addition of 10% Sb2O3 and PVC fillers in the PU matrix shows high cream time, rise time, and tack-free time during the foaming process due to the excellent interaction between these fillers and the PU matrix as compared to other fillers. This may be due to the high density of Sb2O3 and PVC as compare to other fillers. Good interaction between Sb2O3 and PVC as fillers with PU matrix and higher density are responsible for the longer kinetic parameters. The density of the foam is an essential parameter to control the mechanical properties of rigid PU foam when it is expanded and cured in

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its final shape [134]. The density is also an indicator of a foam's individual cavities formed by the nucleation and growth of bubbles within the reacting mixture known as cell size of PU foam, and the foam with a higher density has higher mechanical property [135]. The PU foam density increases from 125.18 to 148.14 kg/m3 with the addition of 10% such as fly ash, ceramic, Teflon, Sb2O3, and PVC fillers in PU matrix as shown in table 5.3. The impact resistance of the foam reflects its ability to withstand mechanical and physical blows without the loss of protective properties and the ability to resist fracture. Impact strength of rigid PU foam prepared from cardanol based Mannich polyols with the addition of 10% fillers such as fly ash, ceramic, Teflon, Sb2O3, and PVC increases with the addition of fillers and shows high impact strength (15.30 – 22.53 J/m) for 10% Sb2O3 and PVC due to the excellent interfacing bonding between the Sb2O3 and PVC with PU matrix as compared to fly ash, ceramic and Teflon. Low impact strength and lower density may be due to the weak bonding and interaction between fillers (fly ash, ceramic, and Teflon) and PU matrix. as a result, the foam becomes brittle due to matrix discontinuity, and each particle acted as a site of stress concentration and led to microcracks [133]. The flexural strength of rigid PUF prepared using different fillers is in the range of 6.737 to 19.550 N. Foams with 10% Sb2O3 and PVC as fillers show higher flexural strength (11.43 –15.95 N) due to good adhesion between fillers and PU matrix. Fly ash, ceramic, and Teflon filler based PU foams show lower flexural strength due to the poor adhesion between fillers and PU matrix. Another reason for the lower strength is the lower densities of the fly ash, ceramic, and Teflon as fillers [134]. PUF with Sb2O3 and PVC as a filler had the closed-cell, low moisture absorption, and good chemical bond strength, as well as good flame retardant properties [136-137]. The variation in flexural strength also followed a similar trend to impact strength and density. The minimum concentration of oxygen, which is expressed as a percentage that will support combustion of a polymer is called as LOI. The flame retardant behavior of PU foam filled with 10% fly ash, ceramic, Teflon, PVC, and Sb2O3, was analyzed by determining the LOI. It could

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be seen that the LOI value increases with the addition of fillers in order of fly ash, ceramic, Teflon, Sb2O3, and PVC [138]. An increase in flame retardancy of PU foam by addition of Sb2O3 filler may be due to the formation of volatile antimony species capable of interrupting the combustion process by inhibiting hydrogen radicals, and by addition of PVC as filler may be due to relatively high chlorine content (56.8%) makes it more resistant to ignition and burning due to presence of chlorine element which significantly disturbs the burning process by formation of HCl which extinguishing the fire. It could be concluded that Sb2O3 and PVC fillers are very efficient flame retardants in rigid PU foam. The surface morphological study of PU foam was done by SEM (Figure 5.8.) to study and identify the cell structure of the filled PU foam [139-140]. Rigid PU foam with the addition of 10% Sb2O3 and PVC fillers having a large number of uniform pentagonal shape cells whereas, by addition of 10% fly ash, Teflon, and ceramic in PU foam shows an increased number of cells with an irregular shape, small size with broken cells walls. This could be the reason for the decrease of the strength with lower density, finally resulting in the foam's brittleness. 10% Sb2O3 and PVC as fillers show uniform structures like pentagonal without broken cell walls. This may be the reason for the improvement in the strength and density of the rigid PUF [141]. The effect of the addition of 10% fillers viz: fly ash, ceramic, Teflon, Sb2O3, and PVC on the thermal stability of rigid PU foams were evaluated by thermogravimetric analysis under an inert atmosphere. The degradation pattern of foam is complex and depends on many factors such as urethane bonds, types of polyols, and unreacted isocyanates [142]. In the first degradation step, less than 5% loss in weight occurs at 220–250°C due to the breakage of the urethane bond of PU and the evaporation of low boiling compounds [143-145]. In the second degradation step, 35-40% loss in weight of rigid PUF containing 10% Sb2O3 and PVC fillers and 50-55% for rigid PUF containing 10% fly ash, ceramic, and Teflon fillers obtained.

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Figure 5.8. SEM of rigid PUF with different fillers (a). Ceramic (b). Fly ash (c). Teflon (d). PVC and (e). Sb2O3 [130].

CNSO and its natural phenol, cardanol, is a unique example of naturally occurring non-edible oil having the properties of phenolic as well as alkenyl structures for the synthesis of polyols for rigid PU foams. The different functional groups within its chemical backbone chain can be either selectively or simultaneously modified by simply choosing the most suitable chemical approach according to the required properties. CNSO and cardanol’s suitability from low-value by-product to high-performance applications in the polymer industry confirms their versatility. Many researchers and industries are working on this molecule with increasing interest in optimizing existing technologies and developing new processes for its purification and chemical functionalization. As a result of the continued advancement in cardanol technology, cardanol remains an everlasting compound suitable as a building block for synthesizing new polyols for the development of novel polyurethanes.

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6. CASHEW NUT SHELL OIL BASED RESIN AS A POTENTIAL REPLACEMENT OF PHENOLIC RESINS FOR VARIOUS INDUSTRIAL APPLICATIONS The global economy presently pirouettes around the petrochemical industry, which created a network of dependency on fossil fuels. However, research is going on developing a new pathway to reduce the dependency on petroleum products. In recent years, studies have been done on replacing fossil resources with renewable and sustainable resources due to limitations and disadvantages of fossil material, such as volatile prices and harmful to the environment [146]. The use of natural, renewable, and lowcost resources like CNSO becomes an excellent option for non-renewable petroleum-based materials because of its chemical versatility for obtaining new materials. CNSO is available in abundant amounts across the world as an agriculture byproduct. Its application in industries is driving economies and contributing to reducing greenhouse gases and pollutants in the environment. The CNSO is one of the vital aromatic bio-feedstocks for many chemical industries. The CNSO is a rich source of a variety of phenolic lipid compounds with unsaturated long aliphatic chains, including anacardic acid, cardol, cardanol, 2-methylcardol, and has many industrial applications [81, 147-164]. CNSO is non-edible oil, it does not show any negative impact on food production and supply compared to some other food crop-based bio-feedstock. Cardanol is non-edible natural phenol obtained from CNSO. It is sustainable, low cost, and mostly available as an agriculture byproduct across the world. Typically, when CNSO is heated at 180-220°C temperature under a 3-4 mm torr vacuum, anacardic acid of CNSO gets decarboxylated to obtained light yellow the liquid is known as cardanol. Cardanol contains a mixture of compounds with varying degrees of unsaturation in the meta-positioned unsaturated alkyl side chains. The phenolic hydroxyl group in the cardanol directs the next incoming groups into ortho and/or para positions of the aromatic ring, providing more synthetic flexibility. The unsaturated/saturated hydrophobic long alkyl

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chain with odd-numbered carbons present in the cardanol gives both amphiphilicity and lipid nature to the system. The phenolic hydroxyl group and cis double bond present in the alkyl side chain of the cardanol is useful for functionalization with different monomers. Cardanol is a precious lowcost starting material for synthesizing various derivatives and polymers [165-166]. One of the most considered cardanol applications is its use as a phenolic precursor for novolac or resole type resin. Indeed, cardanol can undergo condensation with formaldehyde at the ortho or para position of the phenolic ring to form cardanol-formaldehyde (CF) resins [167] (Figure 6.1.).

Figure 6.1. Synthesis of cardanol based phenolic resin [167].

To develop new industrially important products from biomaterial, including CNSO [168-170] several studies have been carried out. The reaction between phenol and formaldehyde leads to the formation of either a resole or a novolac type of phenol-formaldehyde resin. Types of phenolic resin depend on the type of catalyst used and the phenol: formaldehyde (P:F) molar ratio. A phenolic resin prepared in the strong acidic catalyst and a P:F ratio less than 1.0 is called a novolac phenol-formaldehyde resin. A phenolic resin prepared using a basic catalyst and a P: F ratio greater than 1.0 is called a resole phenol-formaldehyde. The CNSO has been studied as a modifier in the synthesis of phenol-formaldehyde resins due to its structural similarity with the phenol [146]. Due to the phenolic nature of cardanol, it reacts with formaldehyde under different conditions to obtained novolac or resoles type phenolic resins [171-176]. Phenolic resins prepared from cardanol and formaldehyde have improved flexibility due to

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The long unsaturated alkyl chain's internal plasticization effect leads to better processability compared with conventional phenolic resins. The alkyl side chain of cardanol gives a hydrophobic nature to the phenolic resin, making it water repellent and resistant to weathering. The low fade characteristics on the friction of CNSO based phenolic polymers make it an essential additive for the brake lining formulations [174]. CNSO based polymers possess excellent resistance to mineral oils' softening action and very good resistance to acids and alkalis [175]. Resin synthesized from cardanol, and formaldehyde exhibits a lower tensile strength than that of phenol-formaldehyde resins. This is maybe due to the steric hindrance and reduced intermolecular interactions imparted by the long alkyl side chain of cardanol [177]. Phenolic resins synthesized from cardanol and formaldehyde are used as matrix material with different natural fibers such as ramie, flax, hemp, jute, etc., as reinforcement materials [178]. Curing of the phenolic resin of cardanol and formaldehyde resin was studied using amine-based catalyst at different molar ratios. During the curing of cardanol-based phenolic resins, water formation leads to porous cured phenolic resins. To overcome this problem, an epoxy resin, diglycidyl ether of bisphenol-A, was mixed with the cardanol formaldehyde resins to reduce the amount of water released during the curing process [179]. Novalac phenol-formaldehyde resins prepared from cardanol were modified to develop epoxy resins with epichlorohydrin to intensify the resins' performance for various applications [180-188]. Phenolic resins were prepared from cardanol and formaldehyde to produce protective varnishes with improved properties in the food industries. The insulating properties of polyvinyl formal (PVF) resin were modified by using phenol– cardanol–formaldehyde-based resin for the enamel varnish to the copper wires. The films of modified P.F resin have excellent water and chemical resistance and can be used as insulating varnish with high electrical resistance, as bobbin enamels and laboratory tabletops [189]. Cardanol based epoxy novolacs and resoles, when modified with phthalic anhydride or linseed oil fatty acids, gave air drying varnishes with relatively low baking temperatures (100oC). Chuayjuljit et al. prepared phenolic resins from cardanol and formaldehyde and reinforced them with natural rubber,

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and remarkable improvements in mechanical properties such as tensile strength, hardness, modulus at 100%, elongation at 300%, and abrasion resistance were obtained [190]. The significant improvements in mechanical properties may be due to the aliphatic side chains of cardanol, which reduces the polar effect of the phenolic resins and, therefore, increases the compatibility with natural rubber. Furthermore, the long alkyl side chains of cardanol revealed flexibility because of internal plasticization. Several studies have been reported on he modification of commercial epoxy resin using cardanol based phenolic resins [186]. Cardona et al. modified phenolic resins using cardanol to widen its applications for modern composite structures [191]. The thermosetting phenolic resins prepared from cardanol and bismaleimide were reported by Shibata et al. [192]. Shukla et al. synthesized toluenesulfonic acid (PTSA) catalyzed phenolic resin from cardanol and maleic anhydride and studied the kinetics of polymerization reaction [193]. Some studies also reported the substitution of formaldehyde by furfural, a bio-based heterocyclic aldehyde obtained from agricultural waste, and the synthesis of cardanolfurfural resins (Figure 6.2.) [194].

Figure 6.2. Condensation of cardanol with furfural and p-hydroxy acetophenone [194].

Thermogravimetric analysis (TGA) of a blend of phenol-formaldehyde and CNSO showed a change in the new resin's thermal stability. Materials like laminates, plywood, etc., when prepared with a blend of resins and CSNO, showed a higher decomposition temperature, making it more resistant to thermal decomposition. Emission of free formaldehyde from phenolic resins was reduced by using 20% CNSO in place of phenol-

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formaldehyde resin [146]. Several phenolic resins were synthesized by condensation of cardanol with hydrogen-rich compounds, such as resols and novolacs [195-199]. The bio-composites were prepared from CNSO derived phenolic resin as a matrix material and the modified sisal as reinforcing material [200]. Phenalkamine, a commercial epoxy curing agent, was prepared by the reaction of cardanol, formaldehyde, and polyamines with ethylene diamine, diethylene triamine, and triethylene tetraamine and characterized by high-pressure liquid chromatography, infrared spectroscopy, and nuclear magnetic resonance spectroscopy [201]. The phenalkamine synthesized using cardanol have a fast cure characteristic at low temperature and permits the application on wet or moistened surfaces [202]. Phenalkamine was in limited use due to its dark and unstable color until Huanga et al. successfully addressed the issue of color and its stability [203]. A novel benzoxazine prepolymer synthesized from cardanol, formaldehyde, and an amine was used to prepare phenolic resins. The process of polymerization was carried out at an ambient temperature in the presence of PCl5. The composites prepared from benzoxazine-based phenolic resins showed good thermal stability, fire resistance, mechanical properties, and flexibility in molecular design [204]. High ortho novolac cardanol formaldehyde resins could be prepared by optimizing the reaction variables. It has been reported [205-207] that if the reaction between phenol and formaldehyde is carried out within the pH range of 4-7 in the presence of oxides or hydroxides of alkali or alkaline earth metals, zinc or aluminium, especially in the presence of electropositive bivalent metal ions, an ortho directing effect occurs, resulting in the production of high ortho novolac resins containing a higher proportion of 2,6 substituted phenolic nuclei. It has been observed that the formation of such isomeric structure is independent of the nature of any anions present [207]. Thus zinc hydroxide, oxide, acetate, formate, benzoate, and valerate give novolac structures of the substantially same percentage of ortho-substitution. The structure is also not affected by changes in catalyst concentration for a given degree of condensation. Moreover, while electropositive bivalent metal ions effectively direct substitution into an ortho position, no directing effect has been observed

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for any monovalent or trivalent ions [207]. Condensations carried out at pH values less than 4 in the presence of Zn+2 and Ba+2 ions yield resins low in ortho substitution, whereas condensations carried out at pH about 5, maximum ortho substitution is obtained [207-208]. Increased ortho substitution was also observed with an increasing phenol-formaldehyde ratio [207]. It was also observed that the ortho directing effect of bivalent metal ions in initial methylolation of phenol extends to further condensation of methylolated phenols reacting between themselves and phenols to form the high ortho novo1ac [207]. Substituted phenols used to prepare substituted phenolic resin differ in their reactivity with formaldehyde [209-210]. The effect of meta substituted long chain in cardanol on the condensation of cardanol and formaldehyde and curing characteristics of high ortho CNSO based novolac resin was studied. Some investigators used accelerators such as m-cresol to prepare high ortho cardanol-based novolac resin under alkaline conditions (pH-9) [211]. Formylation of cardanol in the absence of an accelerator leads to high ortho novolac resin can enable the synthesis of desired novolac resin, containing 2 or 2,6 substitutions. Oxalic acid has been used as an acid catalyst [207], to synthesize phenolic novolac resin with a pH range of 0.51.5. It is known that acids in which there are two carbonyl groups separated by a chain of more than 5 carbon atoms have different properties. The catalytic effect of succinic and adipic acid on formylation of cardanol and curing of cardanol formaldehyde resin has been studied [212-213]. Novolac resins with two different mole ratios namely 1:0.6 and 1:0.8 of cardanol to formaldehyde were prepared using succinic acid and adipic acid as catalyst under pH-4. Resins prepared with lower cardanol formaldehyde mole ratio (1:0.6) with succinic acid catalyst exhibit orthoortho substitution at cardanol; whereas resins prepared with higher cardanol to formaldehyde mole ratio (1:0.8) with succinic acid catalyst exhibit ortho-ortho and ortho-para substitution at cardanol. The order of substitution being ortho- > ortho/ortho- > ortho-/para-/ortho-. This trend is due to the increased reactivity of meta substituted phenol at ortho and para positions during initial formylation [209]. The curing kinetics of the resins showed that the resin prepared with a mole ratio 0.8 possesses increased

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curing characteristics [212]. Adipic acid was also used as a catalyst for the formylation of cardanol [213]. Fast curing CNSO based phenolic resins were prepared using cardanol and formaldehyde with a mole ratio of cardanol to formaldehyde 1:0.6 and 1:0.8 in the presence of the adipic acid catalyst under pH 4. The kinetics of curing of methylolated cardanol showed that resin prepared with the mole ratio 0.6 possesses fast curing characteristics. It was also found that curing of methylolated cardanol leads to condensation with substitution more at 2, 2' ortho-ortho linkage, and lesser at 2, 4' ortho-para linkage. Therefore, adipic acid was used as a catalyst for the preparation of high ortho cardanol formaldehyde resins. The effective utilization of high ortho cardanol formaldehyde resin as active hydrogen (nucleophilic) compound for the polyurethane synthesis could be achieved by functionalizing the cardanol formaldehyde resins. Therefore, the functionalization of cardanol formaldehyde could be carried out by epoxidation and hydrolysis of epoxidized cardanol formaldehyde resins. The condensation product of epichlorohydrin and polyhydric phenol is Epoxy resin. Polyhydric alcohol, like glycerol, ethylene glycol, etc., reacts with epichlorohydrin in the presence of boron trifluoride ethyl etherate catalyst to give epoxy resin [214]. Unsaturated compounds like olefins, when epoxidized by peracids such as peracetic acid, also lead to the formation of epoxy resins [214]. The generally known epoxy resins are derived from bisphenol-A and epichlorohydrin [214]. The hydroxyl group of phenolic resins can be condensed with epichlorohydrin to obtain polyepoxide resins [214]. The acid catalyzed phenolic novolac resins give epoxy-novolac resin by condensing with epichlorohydrin. Epoxy resins have also been prepared by the condensation of CNSO with epichlorohydrin [215-218]. Epoxidation of high ortho multinuclear cardanol formaldehyde resin for functionalization for use in polyurethane synthesis is investigated. The functionalization of epoxidized cardanol formaldehyde resin is an essential step to give active hydrogen groups at the chain ends. These active hydrogen groups at the chain ends of cardanol formaldehyde resins act as a nucleophilic agent. Hydroxyl group-containing compounds are by far the essential nucleophilic agents for reaction with isocyanates [219-

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220]. Primary alcohols, secondary alcohols, and phenols show a decreasing reactivity in that sequence [221]. With the increasing nucleophilic character of these active hydrogen groups, the reaction between active hydrogen group and diisocyanate runs easily at lower temperature forming a stable reaction product. The reaction product formed with a hydroxyl group having low nucleophilic character is not stable, and the reactants can be regenerated at high temperatures [219]. The reaction products with nucleophiles such as phenol, oxime, lactam are not stable [221-222]. Therefore, it is understood that cardanol formaldehyde resin having a phenolic hydroxyl group cannot yield a fast reaction with a diisocyanate to produce a stable polyurethane polymer. Since the hydroxyl group attached as the primary alcoholic group is highly reactive [221] than the hydroxyl group attached as phenolic OH group, functionalization of cardanol formaldehyde resins to give hydroxyalkyl group at the chain ends is an important process for the use of cardanol formaldehyde resin as raw material for polyurethane synthesis. High ortho multinuclear cardanol formaldehyde resins were synthesized using cardanol formaldehyde mole ratios 1:0.6, 1:0.8, and 1:0.9 (Figure 6.3.). Cardanol was weighed into a three-necked flask fitted with a Leibig condenser, ground joint thermometer, and mercury seal stirrer. Formaldehyde (40% solution) was added to cardanol through a chopping funnel along with the catalyst. Adipic acid catalyst (1% based on cardanol) was dissolved in 2 ml methanol under warm conditions and added to the reaction mixture. The pH of the reaction mixture was noted using a pH meter. The reaction mixture was heated to 120±5°C for 3 hr and then at 150±5°C for 2 hr. The initial pH of the reaction mixture was 4, which has lowered to 2 after the completion of condensation. The resins were purified by dissolving in toluene and by precipitating with distilled water. The major fraction was collected and dried using a rotary evaporator under vacuum and analyzed.

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Figure 6.3. Synthesis of cardanol-formaldehyde resin.

Dimerised-cardanol was prepared using catalyst boron trifluoride ethyl etherate. To 100 gm of cardanol was added with boron trifluoride catalyst (2 gm dissolved in 500 ml carbon tetrachloride). The reaction was conducted at 40± 2°C for one hour. The formation of dimerized cardanol was investigated by thin-layer chromatography, UV, 1H-NMR, and IR spectral studies. Iodine value, viscosity, and hydroxyl value were determined. The dimerized-cardanol was used to prepare high-ortho multinuclear dimerized-cardanol formaldehyde resins using dimerizedcardanol formaldehyde mole ratios 1:0.6,1:0.8 and 1:0.9. Adipic acid (1% based on dimerized-cardanol) was used as a catalyst. Methanol was used for dissolving catalyst. Formaldehyde solution (40%) was allowed to react with dimerized-cardanol taken in three-necked flask. The temperature of the reaction was 75oC, and the duration was five hours. The initial pH of the reaction mixture was 4.0. The dimerized-cardanol formaldehyde resins were purified by dissolving in toluene and precipitating with distilled

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water. The major resin fraction was dried using a rotary evaporator under a vacuum. The purified resins were analyzed. High ortho multinuclear cardanol formaldehyde resins were subjected to epoxidation (Figure 6.4.) and hydrolysis (Figure 6.5.) to get hydroxyl alkylated high ortho multinuclear cardanol formaldehyde resin. A definite quantity of cardanol formaldehyde resin was reacted with epichlorohydrin with 2.5 moles of epichlorohydrin per mole of resin. Initially, both the resin and epichlorohydrin were reacted at 70±5°C in a three-necked flask for one hour. The reaction mixture was then cooled to 10-15°C and added with 200 ml of 15% alcoholic sodium hydroxide dropwise with vigorous stirring. Then, the flask's content was heated to 70-80°C and maintained at this temperature for three and a half hours. Then the reaction mixture was cooled, and sodium chloride salt was removed by decantation. The resin was purified by treating with water and then extracted with ether. The extracted resin was dried for removal of ether and then vacuum dried at 60°C for removal of water. The purified resin analysis was done by thinlayer chromatography and infrared spectroscopy to identify the epoxy group in the resin. The epoxidized resin was further subjected to hydrolysis to convert the epoxy group into the hydroxyalkyl group. The epoxidized resin (100 gm) was treated with 50 ml of dilute hydrochloric acid (2N) in a three-necked flask and warmed at 120°C for half an hour and then cooled. The resin obtained was washed with distilled water several times and then dried under vacuum at 60°C using a rotary evaporator and analyzed. Multinuclear dimerized-cardanol formaldehyde resins were subjected to epoxidation. A definite quantity of dimerized-cardanol formaldehyde resin was reacted with epichlorohydrin with 4 moles of epichlorohydrin per mole of resin. Initially, both resin and epichlorohydrin were reacted at 70±5°C for one hour. The reaction mixture obtained was cooled to 1015°C and added with 200 ml of alcoholic sodium hydroxide dropwise with vigorous stirring. The flask content was heated to 75-80°C for three hours. Then the reaction mixture was cooled, and sodium chloride salt was removed by decantation. The resin was purified by treating with water and then extracted with ether. The extracted resin was vacuum dried. The epoxidized resin was subjected to hydrolysis to convert the epoxy group

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into the hydroxyalkyl group. The epoxidized resin (100 gm) was treated with 100 ml of 15% hydrochloric acid and heated to 120°C for half an hour and then cooled. The resin was washed with distilled water several times and then dried under vacuum at 60°C using a rotary evaporator and analyzed.

Figure 6.4. Epoxidation of cardanol formaldehyde resin.

Different methods are used for polymerization of CNSO and cardanol. This includes (i). addition polymerization using cationic initiators such as diethyl sulphate (ii). condensation polymerization through the phenolic rings with aldehydic compound, e.g., formaldehyde (iii). oxidative polymerization etc. The most common polymerization method is condensation with formaldehyde (Figure 6.6.). The polymers derived from CNSO and cardanol shows increased flexibility, diminish brittleness, solubility in organic solvents, good processability, good compatibility with

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other polymers, high performance, and resistance to microbes, insects, and termites. The renewable thermosetting phenolic resin prepared from CNSO was successfully used as a wood adhesive for panels to reduce formaldehyde emission. Excellent adhesive performance and good moisture resistance [223-224].

Figure 6.5. Hydrolysis of epoxidized cardanol formaldehyde resin resin.

A thermal resistant cardanol based phenolic resin was prepared by Wang et al. [225]. The cardanol based boron phenolic resin (CBPR) was synthesized by reacting cardanol with 2-hydroxy benzyl alcohol and boric acid. The resultant resin having improved thermal stability and is used for the development of functional, sustainable adhesive. The formation of CBPR was confirmed by Fourier transform infrared spectroscopy, the thermal stability was investigated by thermogravimetric analysis, and curing behavior was studied by differential scanning calorimetry. The CBPR resin shows outstanding thermal stability. A novel ceramizable phenolic molding composites were prepared from CBPR as matrix material

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using different fillers like nano-aluminum oxide powders, glass powders, and vitreous silica fibers as reinforced material [225].

Figure 6.6. Structure of cardanol–formaldehyde resin (R-side chain).

Novolac phenolic resin was prepared from cardanol using microwave irradiation by Tiwari et al. [226]. The advantage of microwave irradiation method over the conventional methods is drastic reduction in reaction time. The synthesized resin was used for the preparation of the nanocomposite foam and results showed that cardanol could reduce the cross-link density of the phenolic foam and improve the mechanical properties [226]. Resole phenolic resins were modified by copolymerization with cardanol of CNSO. The polymerization was performed under basic conditions with the varying mole ratio of phenol to cardanol to obtained modified phenolic resins [227-228]. The symthesis of Cardanolformaldehyde (novalac) resins was done by the condensation of cardanol and formaldehyde using malonic acid as catalyst (Figure 6.7). The cardanol-formaldehyde resin possesses higher specific gravity and viscosity due to a higher degree of condensation between cardanol and formaldehyde [229].

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Figure 6.7. Synthesis of cardanol formaldehyde resin.

The petroleum-based feedstocks used for the manufacture of resins/polymers are about 4–5% of the world’s oil consumption, and the demand will increase in the future. The challenge is to safeguard the environment by reducing CO2 released, conserve the environment against the harmful effects of the aimless use of petroleum feedstocks, and encourage the reduction of dependence on fossil fuels. Research is going on to replace petroleum-based feedstocks for the development of new innovative materials from renewable and biodegradable feedstocks like CNSO. The CNSO is an agricultural by-product of the cashew industry globally available and is one of the main natural phenols. The cardanol is a major component of CNSO that is of great interest in developing industrially important products like phenolic resins, polyurethanes, paints, varnishes, printing inks, insulation material, and rubber corrosion inhibitor, surface coatings, friction resins, etc.

7. CASHEW NUT SHELL OIL AS A PETROCHEMICAL FEEDSTOCK Renewable resource development which is an alternative to fossil fuel feedstock that is required for the production of different materials which is of prime importance as it is associated with a various concern related to petroleum-based resources. For the development of several sustainable materials, CNSO which is an industrial waste from Cashewnut

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(Anacardium occidentale) processing industry is widely utilized as a renewable source. Petroleum resources or fossil fuel feedstock is believed to be formed thousands of feet below the seabed by decomposition of plants and animals under high temperature and pressure along with other sediment. Before the 19th century, petroleum products had limited applications but in 1815 the modern era of petroleum industry came in light for the first time to obtain crude oil from the brine well located in Pennsylvania, USA [230]. After this, a lot of development took place around North America, Europe, and Asia in the field of the petroleum industry which resulted in the growth of oil products and the processing industry [231]. In the early nineteenth century, with the introduction of automobile industry, petroleum-based feedstocks were in great demand and around the period of 2nd World War, there was a huge development in fossil oil processing/refinery which resulted in a great boost to the petroleum industry and petroleum-based feedstock became a high-end value and multifaceted feedstock for various application [232]. Petroleum-based feedstock/fossil fuel is limited and will not be replaced over time. In response to consumer demands, this feedstock gives several compounds [233]. In 2013, according to the International energy network, approximately the world’s energy consumption of 80% was from the petroleum-based feedstock, 4.6% from nuclear energy, and the rest of it from renewable energy resources and others [233]. Due to industrialization and the increase in the global population, there has been a significant increase in petroleum-based products' consumption and production. The crude oil resources have a wide application from the synthesis of a variety of polymeric materials, biomedical tools, and chemicals that are important and have a lot of application, including structure and packaging materials, lubricant, paints, etc. [234]. In the worldwide consumption of fossil fuel, synthetic plastic alone contributes approximately 7-8% [235]. According to the report, in 2010, approximately 1.40 kgs of plastic per year are consumed by a single person [234-236]. If the use of the petroleum-based feedstock continues, soon it will be depleted. Apart from this, the issue of synthesis of conventional polymer, the use, and disposal is an environmental challenge as most of

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these fossil fuel-based products are non-degradable. The burning of fossil fuel resources like coal, oil, and natural gas over the past decades has made it responsible as one of the major contributors in increasing CO2 levels in the earth's atmosphere, hence being a significant contributor to greenhouse gas emission and associated effects of global warming [237]. Currently, there is a lot of dependence on fossil fuel or petroleum feedstock, there is a need to search for sustainable and renewable bio-feedstocks. The negative impact on our ecosystem and climate, which seems to be with an overloaded carbon footprint, is because of the continuous use and burning of fossil fuel resources [238-242]. Renewable resources is a better option to reduce climate change due to the availability in abundance, being inexpensive, partially or fully degradable, cleaner, and sustainable. Also, it helps to keep away toxic pollutants and hazardous chemicals from the environment; as a result of it people stay healthy. Many manufacturer's major focus is on developing products with renewable resources rather than replacing them with non-renewable feedstock [243]. Renewable resources can be classified into two types: plant resources and animal resources. Plant-based renewable resources, similar to non-renewable resources, can help in obtaining several materials. In the past two decades, steadily, there is an increase in the development of various materials and energy production by using renewable resources. This development gives an opportunity in various sectors such as product development, manufacturing, operation and maintenance, construction, logistics, and transportation and consulting services. Moreover, technologies and/ the industries based on renewable resources help create a job market that is more labor-intensive relative to high capital based intensive and mechanized fossil fuel technologies [244-246]. Renewable-based manufacturing units have low costs for maintenance as well as operations [247-248]. Moreover, rural communities and farmers are benefited since newer technologies utilize renewable agricultural raw materials. Although there has been major progress in using renewable resources worldwide, many countries are still much dependent on imported fossil fuel resources. These imports are vulnerable to political instabilities, trade, and war disputes. Hence, it majorly affects a country's economy, whereas in the

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case of the economy dependent on renewable can help stabilize the prices of fuel, and ups and downs of the countries' economy can be minimized [249]. Thus, as an alternate solution to traditional fossil fuel, the evaluation of new renewable resources seems to have become an attractive topic in case of both, academic as well as industrial research because it has a less environmental impact, degradability, effectiveness in cost as well as high abundance. There has been a growing effort amongst the scientific communities, over the past two decades or so, to encourage the development of process and technologies which are based on crop-based raw materials. The essential sources of crop-based raw materials are wood waste, soybean oil, tung oil, linseed oil, rapeseed oil, castor oil, and cashew nut shell oil (CNSO). Currently, this feedstock uses a lot as raw materials or after modification, which is appropriate in different industries, like surfactants, paints, lubricants, household materials, textiles, purification of wastewater, and applications resins and coatings [250-252]. CNSO, a byproduct of the cashew industry, amongst these raw materials, has gained a lot of importance due to its large availability, and it is easily isolated in good yields. Sivakumar et al. had reported the ability of cardanol oil as a biofuel alternative to diesel [253]. Its higher calorific value and closer molecular weight motivated to select it as a source of alternative petroleum fuel. The absence of sulfur and corrosiveness are the reasons behind the selection of CNSO as a fuel source. CNSO is a mixture of different proportions of its constituents in different percentages. The molecular weight of CNSO is closer to diesel and transesterified biofuel. This eliminates the need for the transesterification process for the selection of this oil as an alternative fuel. From the chemical structure, it has been observed that there is no sulfur content and presence of alcohol, which ensures complete combustion and reduces the formation of polluting hydrocarbon, carbon monoxide, and sulfur oxides during combustion. Cardanol is completely miscible in diesel and alcohol, which again increases the faith of this oil. It was stated by Siriorn puangmalee et al. that cardanol oil could be used as a diesel fluorescent marker [254].

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Different blends of cardanol and diesel were prepared by mixing them in a batch reactor, followed by a stirring of about 10 minutes. Blend ratios have been prepared on a mass basis, and the rangeof cardanol with diesel varies from 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100% respectively. The eynthesized cardanol-diesel blend has been studied for its physical and chemical properties. On the basis of the test reports blend has been optimized. The test has been performed under the standard conditions mentioned by the ASTM method. The essential properties are viscosity, density, calorific value, flash point and fire point, sulfur content, corrosive nature, and molecular weight tested for selecting biofuel blend. From the test reports, it can be concluded that blend cardanol 40% and diesel 60% can be selected for further studies without any modifications in the engine's hardware. As viscosity value of this blend comes under the standard specification accounted by both ASTM and ISO for biofuel. The calorific value and flash and fire point also higher than the required condition for biofuel. With the above-discussed points, blend B40 can be selected as the best optimum blend ratio. The higher blends B50 and B60 can be selected for further studies bypreparing an additional blend with 5% or 10% of ethanol or diethyl ether so that the viscosityis reduced which is the ultimate goal is to reduce the diesel percentage in combustion. Further studies can be carried out on the optimized blend ratio for the analysis of combustion, performance, and emission in the diesel engine with different loading conditions like no-load, part load, and full load [255]. The influence of CNSO in biodiesels' oxidative stability prepared from oils of soy, corn, canola, and sunflower was studied using the Rancimat method [256]. The CNSO is chosen as a suitable oil for the production of biodiesel. In the diesel engine, the utilization of CNSO blends can be as an alternative fuel. The performance and emission analysis of both the biodiesel fuel types show that they are a better alternative to diesel. Except for NOX emission, the other emission levels of the various blends of CNSO are less compared to that of diesel. The emissions of CNSO blends can further be decreased by the usage of additives [257]. It has been observed by various studies that non-edible oil can be used in the neat form, but it is not preferred because of the high viscosity, and low

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volatility of the non-edible oil affect atomization and spray patterns of the fuel, which results in incomplete combustion and severe carbon deposits, injective choking and piston ring sticking. To reduce the viscosity, the methods used are (i) Emulsification, (ii) Pyrolysis, (iii) Dilution (iv) Transesterification. To obtain clean and eco-friendly fuel from CNSO, pyrolysis, and transesterification methods are used [258]. Further processing such as transesterification was not required in the biodiesel obtained from CNSO [259]. Risfaheri et al. described the pyrolysis process of CNSO [260]. Linus et al. have discussed the production of biodiesel from CNSO [261]. In a conical flask, 50ml (36 gm) of CNSO was taken. Then it was preheated to 70°C. In another conical flask (0.225 gm) of NaOH was added to 20 ml of methanol, and they were properly mixed and stored until the pellet dissolved to obtain sodium methoxide. Then sodium methoxide solution was added in preheated CNSO. To obtain homogeneity, the solution was properly mixed. The same process was carried out using potassium hydroxide as a catalyst. The reaction was carried out at 70°C for 1.5 hrs. The product obtained was taken in a separating funnel and left overnight so that the glycerine produced can be properly settled. Fatty acid methyl ester, which is a product of transesterification reaction, had impurities such as unreacted methanol, potassium methoxide, and glycerol, which is the by-product of biodiesel, so purification was required so that it can be used in the diesel engine. The purification process was done by washing biodiesel. In this, 30 ml of water was poured on the product and was gently mixed to prevent foam formation. Then, the water and biodiesel mixture remained as such for 5 hours to obtain two phases, i.e., water impurities phase and biodiesel phase, then they were separated with the help of a separating funnel. Drying was recommended. Velmurugan et al. conducted an experimental evaluation of a diesel engine's performance and emission fuelled with CNSO and its blends (B20, B40, B60, B80, and B100), and a comparison has been made with neat diesel operation [262]. Mallikappa et al. evaluated the four-stroke single-cylinder engine's performance and emission characteristics with various loads using cardanol biofuel with volumetric blends of like 0%,

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10%, 15%, 20%, and 25% [263]. The authors used a two-stage distillation method to produce cardanol from CNSO, as, in the single-stage distillation method, certain difficulties were encountered in operation. The transesterification process was used to produce cardanol, which was used as a raw material in biodiesel production. It was observed that the brake specific energy consumption was approximately reduced by 30 to 40% with an increase in the load condition. This reverse trend was obtained because of the lower calorific value with the increase in the biofuel percentage in the blends. It was found that the brake thermal efficiency increased with higher loads. It was seen that in all cases, it increased with the increase in load. The maximum thermal efficiency of 31% was obtained for B20, which was higher compared to diesel. An increased proportion of blends and higher exhaust gas temperature is observed with an increase in the NOx emissions (ppm). Mainly, this kind of trend is due to oxygen in biofuel, which leads to higher temperatures due to more oxidation and is responsible for the emission of NOx. The incomplete combustion is responsible for the nominal emissions of HC up to B20 and more at B25. The emission of CO increases with higher blends and is slightly more after 20% blends. It is seen that at a higher temperature, there is an improvement in the performance of the engine with better results in the burning of the fuel, which results in a decreased of CO. It has been observed in the evaluation that up to 20% cardanol blends biofuels can be used in the compression ignition engine without requiring any modifications. Mallikappa et al. evaluated the emission and performance of three stationary diesel engines that were operated with 20% cardanol biofuel volumetric blends [264]. Some tests on a single-cylinder diesel engine and variable compression ratio engines were conducted so that an evaluation of the emission and performance characteristics of cardanol biofuel could be carried out. On a double cylinder compression ignition engine, an experimental study, was done to evaluate the performance and emission characteristics. Testing was done at various loads between 0-full load for the volumetric blends of cardanol biofuel between 0-25% and base fuel (Petrodiesel). Velmurugan et al. tested biofuel, diesel, and ethanol blends (BDEB), a single-cylinder direct injection diesel engine, to evaluate

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engine combustion performance and emission characteristics of the engine at a speed of 1500 rpm under five different engine loads [265]. Radhakrrishnan et al. evaluated the emission characteristics of a fourstroke single cylinder engine in which CNSO was used as a fuel to test whether CNSO diesel blends can be used as an alternative to fuel or not [266]. A single cylinder four-stroke direct injection compression ignition engine with a compression ratio of 17.5: 1 was used in the experiment. In the experiments, static injection timing 18°, 19°, 21°, 23°, 26°, and 28° TDC and injector opening pressure 200 kg/cm2 were performed. It was observed that there is an increase in brake thermal efficiency as the injection time is increased from 18° to 19°bTDC. It was also observed that the variation of smoke density reduced as the injection time advanced for the CNSO oil blends. Hydrocarbon emission was found to be lowest with the best injection timing of 19°bTDC, which is attributed to the fuel taking part in the premixed phase of combustion. Lower NOx emission was obtained in blends of CNSO compared to the neat diesel fuel. This is attributed to the poor mixture formation due to low volatility, higher viscosity, and higher density of CNSO. Among the B20, B40, B60, B80 blends, B20 blends were found to give higher thermal efficiency since other blends give the high viscosity of fuel and poor atomization and hence poor combustion. The specific fuel consumed by CNSO is higher than that of diesel of all loads because of the higher viscosity and poor mixture formation of CNSO. The unburnt hydrocarbon emission of the blends of CNSO is more than neat diesel for all loads. It is observed that carbon monoxide emission is higher while the exhaust temperature of CNSO oil is decreased due to poor combustion compared to neat diesel. The study also conducted on the CI engine with diesel, and cardanol blends with methanol as an additive at actual injection timing leads to the following conclusions; (i). The addition of 10% methanol showed changes in properties of cardanol blends (ii). For B20M10, brake thermal efficiency was improved by 2.08% (iii). BSEC was reduced by 8.3% (iv). In the case of emissions, 8%, 2.1%, 1.89%, and 23.2% reductions were observed in CO, HC, SO, and NOx, respectively. Hence, 10% methanol can be used as an additive to

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improve the performance and emission characteristics of a single-cylinder diesel engine for the B20 cardanol blend [267]. CNSO is found to be useful in fuel blends and fuel mixtures [268] and for the production of diesel oil [269]. A brown colored liquid product known as diesel fuel is generated on cracking of CNSO at 500°C for 2 hr with a molecular sieve. As an alternative fuel, CNSO was used for the diesel engine. The viscosity of CNSO is 30-35 times higher than that of diesel; therefore, the properties and uses would vary with different blends of CNSO. The engine's performance is optimized by modifying the oil and its application, such as injection pressure, preheating the oil, etc. Results obtained indicated that preheating of blends of CNSO at 200 kg/cm2 injection pressure and 28° injection timing were suitable for commercial purposes [270]. When CNSO is used in the engine as bio-additive, there is an increase in the durability of the equipment. Hence, there is a reduction in dependency on products of petroleum along with the preservation of the environment with the application of CNSO as it lowers the residues of the pollutant from fuel combustion products. Nair et al. prepared biodiesel composition which has distilled technical cashew nut shell oil and at least one product of petroleum which is selected from a group which comprises diesel and a concentration ranging between 70-99.9% v/v optionally of kerosene along with plant oils and fuel additive(s): the aim was to provide improved biodiesel composition [271]. Risfaheri et al. narrate the pyrolysis procedure of CNSO. The pyrolysis was done in a reactor at a vacuum pressure of 5 kPa and temperature between 400-600oC [272]. The volatiles removed on pyrolysis is gradually condensed from atmospheric condensation to condensation in an ice bath (5-7oC). The decarboxylated cardanol is termed as CNSO biodiesel. The biodiesel obtained from CNSO not required further processing like transesterification. The CNSO based fuel is cheaper than the other kinds of vegetable oils based fuels. Therefore, CNSO blends can be used in CI engines in the urban and rural areas for meeting energy requirements. Hence CNSO can be alternately used as fuel for a diesel engine without any modification.

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8. CASHEW NUT SHELL OIL: AN ECO-FRIENDLY ALTERNATIVE FOR THE MODERN COATING INDUSTRY In the coating industries from ecological and economic aspects, the maximum utilization of the materials, which is natural in origin for the polymer synthesis, can be an obvious option. In the same line, partial substitution and, to some extent substituting totally, petroleum-based raw materials with an equivalent or even enhanced performance is the cashew nut shell oil (CNSO). The viscous dark brown-colored liquid which is obtained from cashew nutshell is used in the number of polymerization reactions because of its phenolic structure, which is a reactive and unsaturated aliphatic chain that is meta-substituted. Hence, many resins from CNSO can be synthesized, such as polyester resin, epoxy resins, acrylics, alkyds, etc. CNSO and its derivatives are an alternative to petroleum-based raw materials as far as the polymer and coating industry is concerned [273]. A lot of research on the chemistry based on petroleum feedstock such as epoxy, alkyd, polyurethane, phenolic, polyester, silicates, etc., has been done in the coating industry. They play an important role in the coating industry; their use has been overshadowed by the economic and ecological aspect in the modern coating industry: The resin prices, high depletion rate, handling issues, toxicity, and health hazards related to petroleum-based materials and volatile organic compounds which are released in the environment while synthesis and applying petroleum-derived chemistries as they are volatile in nature. Hence, it is imperative to explore a new sustainable, non-hazardous, economical alternative. For the synthesis of polymer/resin, one of the alternatives is the use of bio-based materials. Biomaterials have gained a lot of interest worldwide since their origin is naturally available in plenty, which would have a significant contribution towards global sustainability. Moreover, handling bio-based materials would be easy, with no or less toxicity and health-related issues. Moreover, bio-based polymers have an advantage over petroleum-based polymers as they are degraded in a controlled manner in the biological environment by

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the enzymatic action of micro-organism and increasing conversion of the biomass, methane, carbon dioxide, water, and other natural substances [274-275]. Thus, due to the advantages related to the biomaterials such as ease of availability, more economical, and less environmental impact has made it a topic of interest in academic and industrial research for synthesizing polymers and functional chemicals used in the coating industry [276]. Many literature is available on using bio-based material as such or with chemical modification, using a variety of applications such as resin synthesis, paints, coatings, composites, etc. [277-283]. The bio-based materials include starch, cellulose, sugar, lignin, plant and animal oils, CNSO, etc. CNSO can be used as an alternative to petroleum-based material since it has an advantage in its availability, sustainability, reactive functionalities, and cost-effectiveness. CNSO and their derivatives have many advantages compared to other renewable oils as they contain a lot of phenolic derivatives with meta substituted long-chain saturated/ unsaturated hydrocarbon, which makes it possible to carry out many polymerization reactions via addition and condensation mechanism. Moreover, due to the incorporation of the aromatic ring and a long-chain hydrocarbon, there is a good balance between the flexibility and hardness properties of the coating. Several industrial applications are based on this, including laminating resin, adhesives, paint, coating resins, foundry chemicals, lacquers, fine chemicals, hybrid materials, surface activeagents, waterproofing agents, wax compounding, etc. (Figure 8.1.). As there is a presence of phenolic hydroxyl, a step synthesis of epoxy resin with 100% conversion is possible, unlike epoxies that are obtained from oils. Moreover, an epoxy synthesis that is based on CNSO does not use hazardous chemicals like peroxides, which are used in the epoxidation of oils. Hence, CNSO based resins synthesis does not have any health-related or handling issues. Chemically unmodified CNSO has been reported as a corrosion inhibitor that reduces carbon steel's corrosion rate by over 90% because phenolic hydroxyl gets adsorbed on the metal substrate [284]. CNSO and their derivatives have structural similarity to toxic phenolic compounds hence CNSO and their derivatives can replace toxic phenolic compounds in resin synthesis, such as phenols in a phenolic resin,

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bisphenol-A in epoxy resin synthesis with better properties. In some cases, conventional epoxy resins are replaced by epoxy resin obtained from CNSO as they gave equivalent or higher performance properties. Moreover, chemically modified CNSO can replace hydroxyl functional resin, which is obtained from petroleum-based stocks that can be used in polyurethane synthesis, crosslinkers, etc., with higher performance properties. Conventional toxic plasticizers such as dioctyl phthalate, dibutylphalate, and diethylhexylphthalate, which have application in polyvinyl chloride (PVC) processing, can be replaced esterification of CNSO. Modified CNSO can replace commercial phenols, which are used for antioxidant purpose.

Figure 8.1. Potential applications of CNSO and its derivatives [285-287].

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CNSO and their derivatives can undergo a number of chemical reactions, some of them being sulfonation, nitration, esterification, halogenation, etherification, epoxidation, etc. (Figure 8.2.).

Figure 8.2. Possible reactions of CNSO and their derivatives.

When epichlorohydrin reacts with CNSO, epoxidation of the phenolic group takes place [288]. The chemical modification which takes place in this reaction is similar to the conventional synthesis of epoxy. Unnikrishnan et al. studied the replacement of phenol or diphenol with cardanol in the synthesis of epoxy resin and compared it with conventional epoxy. Moreover, they have studied the combination of cardanol and bisphenol-A, and they observed that when 20 mol% of cardanol was added to bisphenol-A, it gave resin with reduced tensile, impact and compressive strength on curing with a polyamine hardener but observed that the elongation-at-break was considerably improved without much decrease in energy absorption. CNSO, which is of natural origin, undergoes a reaction similar to phenol since it has a phenolic structure. Moreover, additional

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active sites can be created by the presence of a long chain of unsaturated hydrocarbon. A variety of resins/polymers can be synthesized, such as epoxy, alkyd, polyurethane, phenolic resin, vinyl, etc., using CNSO. Moreover, the formulation can be done for these synthesized resins for various coatings such as epoxy coating, waterborne coatings, UV-curable coatings, modified polyurethane coatings, and phenolic coatings, etc. as shown in figure 8.3. Several authors have reported different aspects such as varying reaction conditions, the number of reaction catalyst, and various process parameters used to polymerize CNSO [289-292].

Figure 8.3. Thecoating based on CNSO and its derivatives.

CNSO based surface coating possesses excellent gloss and surface finish with optimum levels of toughness and elasticity. It has wide use in the manufacture of paint and varnish to control properties and reduce cost. It is an excellent raw material for a number of anti-corrosive paint formulations. Tan et al. prepared cardanol–glycols (CGs) and cardanol glycol polyurethane (CGPU) films [293]. The films were characterized by using FTIR, 1H-NMR spectroscopy, swelling test, and differential scanning calorimetry (DSC) studies. In CGPUs, the cardanol content was

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inversely proportional to glycol's molecular weight, which affected the crosslinking density of the films. It was observed that the swelling property and glass transition temperature were affected by reducing the crosslinking density. Auto-oxidation auto-polymerization of the double bond of the cardanol side chain in the presence of cobalt salt catalyst enhanced the crosslinking of CGPUs. Gopalkrishnan et al. synthesized tough and crosslinked polyurethane from CNSO in three steps [294]. In the first step, cardanol was reacted with formaldehyde in three different molar ratios to obtain cardanol-novolac resin. The the second step involves epoxidation of synthesized cardanol based novalac resin. In the third step, hydrolysis of epoxidized resin was carried out to get hydroxy alkylated cardanol– formaldehyde resin. The prepared hydroxyl functional resin and a commercial polyol (PPG-2000) were taken to cure diphenylmethane diisocyanate (MDI). It was found that the polyurethane prepared by a higher mole ratio of cardanol/formaldehyde of hydroxyalkylated cardanol– formaldehyde resin showed better thermal and mechanical properties compared to polyurethane prepared using a lower molar ratio. Asha et al. prepared UV-curable urethane–methacrylate crosslinkers from cardanol using one-pot synthesis [295]. The method used was end-capping of isophorone diisocyanate with an equivalent amount of hydroxyethyl methacrylate and then condensation with cardanol. The characterization technique used for the confirmation of their structures were FTIR, 1HNMR, 13C-NMR, matrix-assisted laser desorption/ ionization-time of flight (MALDI-TOF) spectroscopies, and size exclusion chromatography (SEC). The formulation of the prepared acrylate oligomer for UV-curable coatings was done. The result showed that cardanol and its derivatives, which possess hydrogen-bonded crosslinkers, had higher bond conversion than non-hydrogen bonding standards like hexanediol diacrylate (HDDA) obtained in similar conditions. The effect of temperature on hydrogen bonding and the curing process was evaluated. The anti-biofouling influence of some naturally unsaturated hydrocarbon like cardanol and lacquer tree sap has been reported. Kim et al. used the enzymatic reaction to polymerize cardanol and use it as an anti-biofouling coating material [296]. Choi et al. prepared

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polydimethylsiloxane (PDMS) matrices impregnated with natural unsaturated hydrocarbon phenols, i.e., urushiol, obtained from the sap of natural lacquer tree and a mixture of cardol and cardanol from refined CNSO and evaluated it as an antifouling agent [297]. Adding the natural unsaturated phenol exhibited excellent anti-microbial property towards Escherichia coli and Saccharomyces cerevisiae. Ramasri et al. prepared water-soluble Mannich bases from cardanol and phenol [298]. The influence of the electrodeposition parameters on the film formation from the prepared binder and the pigmented composition was evaluated. The results revealed that a uniform coating with good mechanical properties was obtained from the polymer. Moreover, the pigmented system showed good resistance to organic solvents and gave excellent corrosion inhibition. Water-based coatings have been in use for decades, as they eliminate or reduce the use of petroleum-based solvents, which increase levels of VOCs, toxic substances, and energy consumption. The coatings industry focuses on four major techniques in eco-friendly technologies: watersoluble coating, powder coating, radiation-curable coating, and high-solid coating [299]. In this regard, aqueous, cashew nut shell oil (CNSO)-based coatings have received increased attention because of the availability of agro-based CNSO. The CNSO constituents have two reactive units: phenolic -OH, which is the hydrophilic part of the molecules, and the long C15 side chain having two double bonds (i.e., the hydrophobic part that contributes to cross-linking and gives gradual and satisfactory drying and baking properties) [2]. The long hydrocarbon chain imparts excellent flexibility to its aldehyde condensate in the various drying oils. CNSO exhibits unique properties like excellent water resistance, corrosion inhibition, good chemical resistance, improved flexibility, and drying compared to the other oils. Despite having these properties, CNSO has limitations such as lack of hardness, lack of toughness, and poor adhesion. The problems may be taken care of by modifying CNSO with epoxy resins, which impart adhesion, toughness, improved film hardness, and resistance to chemicals [300]. A study has been carried out to synthesize water-based CNSO-modified resins and assess the advantages of blending

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CNSO with maleinized epoxy ester resins for coating properties, especially corrosion resistance, humidity, and blistering. The following steps were adopted to synthesize water-based CNSO-modified resins [301]; (i). Synthesis of epoxy resin (ii). Synthesis of maleinized fatty acids (iii). Preparation of maleinized fatty acid epoxy ester resins (iv). Preparation of CNSO modified resins.

8.1. Synthesis of Epoxy Resins To synthesize epoxy resins, a calculated amount of epichlorohydrin and bisphenol was kept in a three-necked flask, fitted with a reflux condenser, thermometer pocket having a thermometer, dropping funnel, dean-stark and mechanical stirrer. The reaction mixture obtained was heated to 60°C with stirring, and then with the help of the dropping funnel an aqueous sodium hydroxide solution (20% w/v))l with continuous stirring. .Then he resin solution was distilled off under reduced pressure to get a transparent form of epoxy resin.

8.2. Synthesis of Maleinized Fatty Acids Maleinized fatty acids were put in a multi-neck flask containing a reflux condenser, thermometer in thermometer pocket, and a mechanical stirrer. It was heated to 90°C with constant stirring. 8% of maleic anhydride was slowly added for 20-30 min. On complete addition of maleic anhydride, the temperature was raised to 200-210°C. The temperature was maintained until the desired acid value was obtained and hydration was carried out by boiling maleinized fatty acids in water for about 1 hr. Excess of water which was unreacted was distilled off under reduced pressure.

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8.3. Synthesis of Maleinized Fatty Acid Epoxy Ester Resins Maleinized fatty acids were put in a multi neck flask containing a reflux condenser, thermometer in thermometer pocket, and a mechanical stirrer. The temperature was raised to 100-110°C with continuous stirring. Fatty acids that were maleinized were reacted with 30% of epoxy resin at 145°C. The samples were withdrawn from the reaction mixture, and the acid value was checked.

8.4. Synthesis of CNSO-Modified Resins To synthesize water-based CNSO-modified resins, a calculated amount of maleinized fatty acid epoxy ester resins were kept in a multi necked round bottom flask. Based on maleinized fatty acids, the addition of 5 to 25% of CNSO was done at 110-115°C. The samples were removed from the reaction mixture to check the acid value. The co-solvent ethylene glycol monopropyl ether was added at around 80°C to the final resin. Resins were neutralized with trimethylamine and solubilized in distilled water to get the desired viscosity. Surface preparation of the panels was carried out by using emery paper, xylene, mineral turpentine oil, detergent, and water [302]. For the panels' application, appropriate quantities of diluted resins were applied over mild steel and glass panels. The curing of resins was done at 120°C for 30 min. The film's evaluation as per the standard test for acid resistance, alkali resistance, corrosion scratch test, adhesion, and hardness was done. The artificial seawater sample was prepared by dissolving chemicals in 1 liter of water for corrosion scratch test (Table 8.1). A corrosion scratch test was performed on mild steel panels. The 5cm x 10cm x 1mm thick mild steel panels were first degreased, sanded, and then coated. The coated panels were left as such for a week at room temperature so that they are completely cured. They were edged with wax, and one face of every panel of the substrate was scratched with a sharp blade. The panels were kept in artificial (synthetic) seawater for 400 hrs

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and then washed with distilled water. Then the panels were dried, and they were observed for rusting. Evaluation of the specimen is done periodically to check rusting and blistering [302]. Table 8.1. Chemicals used in artificial seawater [302] Chemicals Sodium chloride Magnesium chloride Magnesium sulfate Calcium sulfate Potassium chloride Potassium bicarbonate Potassium bromide

Weight (gm) 28.05 2.95 1.75 1.30 0.65 0.15 0.10

Humidity test was performed by using cold rolled mild steel panels that had no rust. One side of the sample was contaminated by 200 and 700 mg/m2 of Cl-, SO4-2, and NO-3. Uncontaminated mild steel samples were taken as controls. Distilled water and reagent grades were then used to prepare sodium chloride, sodium sulfate, and sodium nitrate solutions. Application of the above coating was made on the mild steel panels, and the panels were kept for a week at room temperature for curing. Then, the strip coating was applied on the contaminated side of the panel. Wax was used to seal the edges of the panel. 50 µm thick coating was applied, and the time of exposure was 100 and 400 hrs. According to ASTM D610 and D714 specifications, the samples were checked for rusting and blistering, respectively. The weight-loss method measured the under-film corrosion rate by weighing the specimen before the contaminants were applied and after the test and by removing the coating and corrosion products [302]. Humidity test was performed by using cold rolled mild steel panels that had no rust. One side of the sample was contaminated by 200 and 700 mg/m2 of Cl-, SO4-2, and NO-3. Uncontaminated mild steel samples were taken as controls. Distilled water and reagent grades were then used to prepare sodium chloride, sodium sulfate, and sodium nitrate solutions. The above coating was applied on the mild steel panels, and the panels were left for a week at room temperature for curing. Then, the strip coating was

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applied on the contaminated side of the panel. Wax was used to seal the edges of the panel. 50 µm thick coating was applied, and the time of exposure was 100 and 400 hrs. Table 8.2. Characteristics of intermediates and final products [302] S.N.

Characteristics

Epoxy Resin

Maleinized Fatty Acids

Epoxy Ester

1. 2. 3. 4. 5. 6.

Epoxy Equivalent Acid Value Unreacted Maleic Anhydride Clarity Solubility in Water Colour

325 Clear Yellow

231 1.82% Clear Soluble Light Yellow

117 Clear Soluble Light Yellow

(a).

(b).

(c).

(d).

CNSOModified Resin 92 Clear Soluble Brown

Figure 8.4. FTIR spectrum of (a). Epoxy resin (b). Maleinized fatty acids (c). Maleinized fatty acids epoxy ester resins (d). CNSO-modified resin [302].

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According to ASTM D610 and D714 specifications, the samples were evaluated for rusting and blistering, respectively. The weight-loss method measured the under-film corrosion rate by weighing the specimen before the contaminants were applied and after the test and removing the coating and corrosion products [302]. With regards to the solubility in water and clarity of solutions, the CNSO-modified resins are soluble in water, and solutions are clear due to sufficient polarity with the resin. The cured samples derived from CNSObased waterborne resins (Table 8.3 (a) & (b).) have been coded as S1, S2, S3, S4, and S5. Films of all the samples were found to be glossy, clear, transparent but appeared brownish-yellow due to the dark brown color of cashew nut shell oil. Table 8.3. (a). Composition and test results of cured films of Maleinized Epoxy Ester [302] S. N. 1. 2. 3. 4. 5.

Sample Code S1 S2 S3 S4 S5

CNSO in Resin 05% 10% 15% 20% 25%

Water Resistance Good Good Good Good Good

Acid (3%H2SO4) Resistance Good Good Good Good Good

Alkali (2%NaOH) Resistance Good Good Good Good Good

Table 8.3. (b). Composition and test results of cured films of Maleinized Epoxy Ester [302] S. N. 1. 2. 3. 4. 5.

Sample Code S1 S2 S3 S4 S5

CNSO in Resin 05% 10% 15% 20% 25%

Impact Resistance Passed Passed Passed Passed Passed

Corrosion Scratch Passed Passed Passed Passed Passed

Flexibility/Adhesi on & Hardness Passed Passed Passed Passed Passed

The tests for water resistance, acid resistance, alkali resistance, impact resistance, corrosion scratch, flexibility/adhesion, and hardness were done

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on all the cured resins samples. The results obtained are summarized in Table 8.3. (a) & (b). All the samples have shown good water, acid, and alkali resistance. All the analyzed samples passed the impact and adhesion test as the epoxy group was present, which shows good adhesion as there is a polar hydroxyl group and epoxide group. The presence of a sufficient amount of fatty acids and cashew nut shell oil, which act as an internal plasticizer, results in reduced cohesive forces and improvement in adhesion, which combined impact toughness. No damage or cracks were observed in any of the samples, and the samples passed the test. The corrosion scratch test possessed good corrosion protection. The presence of cross-linking points in maleic anhydride provides better hardness to the film. It was also found that none of the samples showed any kind of detachment of the film from the substrate. Table 8.4 depicts the results of humidity blister and under-film corrosion rate after being exposed for 100 and 400 hrs. Both rusting and blistering were rated by visual examination and compared with ASTM D-610 specification and ASTM D-714 specification. The under-film corrosion rate was obtained by the weight loss method after 100 and 400 hrs. The resin coated panels having a low percentage of CNSO depict stronger rusting and blistering than those coated with a high percentage of CNSO. The result shows that the water present at the coating metal interface is responsible for adhesion failure, which agrees with the literature. The coating behaves as a semi-permeable membrane. The blisters are formed by the contamination because the water permeates through the film, and the concentration of the contaminant is decreased. Blisters are responsible for the failure of the coating. Results show that 100 hrs are enough for the water to penetrate through the coating, which is responsible for dissolving the contaminants present in the coating-metal interface. However, it is not sufficient to produce perforation of the coating due to the accumulation of water or the growth of rust [303]. The underfilm corrosion depends on the contaminant's concentration, which is present in the interface but is not dependent on the type of contaminant. In the lower percentage of CNSO coatings, the under-film corrosion is higher than those samples which have a higher percentage of CNSO.

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Table 8.4. Test Results (a). Humidity test (b). Blistering test (c). Under-film corrosion rate test [302] Test Method (Film thickness 50µm, Conc. of Sample Code contaminants 300 mg/m2) S1 S2 S3 S4 S5 Humidity Test NaCl 100 hr 8 9 10 10 10 ASTMD610 400 hr 7 8 8 9 10 Na2SO4 100 hr 8 8 8 9 9 400 hr 6 7 8 8 9 NaNO3 100 hr 8 9 9 9 10 400 hr 7 8 8 9 9 Test Specification for Humidity Test: Numerical rusting scale is expressed as area of rusted surface (10