Synthesis of High-Quality Biodiesel Using Feedstock and Catalyst

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Synthesis of high quality biodiesel using feedstock and catalyst derived from fish wastes Devarapaga Madhu, Rajan Arora, Shalini Sahani, Veena Singh, and Yogesh Chandra Sharma J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.6b05608 • Publication Date (Web): 23 Feb 2017 Downloaded from http://pubs.acs.org on February 25, 2017

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Journal of Agricultural and Food Chemistry

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Synthesis of high quality biodiesel using feedstock and catalyst derived from fish wastes

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Devarapaga Madhu1, Sharma1*

4 5

1

6 7

2

8

*Corresponding author

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E mail [email protected], Tel No. +91 542 6702865, Fax +91 542 6702876

Rajan Arora2, Shalini Sahani1, Veena Singh1,

Yogesh Chandra

Department of Chemistry, Indian Institute of Technology (BHU) Varanasi, Varanasi 221005, India. Department of Chemical Engineering and Technology, Indian Institute of Technology (BHU) Varanasi, Varanasi 221005, India.

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A manuscript submitted for publication in:

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Journal of Agriculture and Food Chemistry

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1 ACS Paragon Plus Environment


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Synthesis of high quality biodiesel using feedstock and catalyst derived from fish wastes

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Devarapaga Madhu1, Sharma1*

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1

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2

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*Corresponding author

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E mail [email protected], Tel No. +91 542 6702865, Fax +91 542 6702876

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ABSTRACT

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A low cost and high purity calcium oxide (CaO) was prepared from waste crab shells which

25

were extracted from the dead crabs, used as efficient solid base catalyst in the synthesis of

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biodiesel. Raw fish oil was extracted from waste parts of fish through mechanical expeller

27

followed by solvent extraction. Physical as well as chemical properties of raw fish oil were

28

studied and its free fatty acids (FFA) composition was analysed with GC-MS. Stable and

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high purity calcium oxide (CaO) was obtained when the material was calcined at 800 °C for

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4 h. Prepared catalyst was characterized by XRD, FT-IR, and TGA/DTA. The

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structure of the catalyst was analysed with SEM and elemental composition was determined

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by EDX spectra. Esterification followed by transesterification reactions were conducted for

33

the synthesis of biodiesel. Effect of co-solvent on biodiesel yield was studied in each

34

experiment using different solvents such as toluene, and diethyl ether, hexane,

35

tetrahydrofuran (THF) and acetone. High quality and pure biodiesel was synthesized and

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characterized by 1H NMR and FT-IR. Biodiesel yield was affected by the parameters such

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as reaction temperature, reaction time, molar ratio (methanol: oil) and catalyst loading.

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Properties of synthesized biodiesel like density, kinematic viscosity, cloud point, etc. were

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determined according to ASTM standards. Reusability of prepared calcium oxide (CaO)

Rajan Arora2, Shalini Sahani1, Veena Singh1,

Yogesh Chandra

Department of Chemistry, Indian Institute of Technology (BHU) Varanasi, Varanasi 221005, India. Department of Chemical Engineering and Technology, Indian Institute of Technology (BHU) Varanasi, Varanasi 221005, India.

surface


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catalyst was checked and the catalyst was found stable up to five runs without significant loss

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of catalytic activity.

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Key words: Fatty acid methyl esters (FAME’s); Free Fatty Acid; Tetrahydrofuran; Waste

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crab shells; Waste fish oil.

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1. INTRODUCTION

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Energy has pivotal role for determination of socioeconomic conditions of any country.

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Energy consumption of any country determines the country’s standard of living1. The excess

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of energy in the surroundings can be converted, accumulated and amplified for our daily use

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in a number of ways. The production of energy has always been a concern for researcher and

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policymakers worldwide. Energy sources are categorized into two main groups, namely

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fossil and renewable energy. Fossil energy can be separated into non-renewable and

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renewable energy. Non-renewable energy sources comprise petroleum, coal, gas hydrate, gas

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and fissile material and renewable energy sources include solar, hydro, geothermal, biomass

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and wind energy. Recently, the renewable energy sources are contributing more towards the

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total global energy requirement2. Supporting development, indispensable characteristics of

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renewable energy source depend on environmental protection.

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The world energy currently conflicted with the turning point of fossil fuel depletion and

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environmental deterioration. To prevail this problem, renewable energy has currently been

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achieving more attention because of its environmental allowance. The need for energy, the oil

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depletion and its price which are continually increasing, all have inclined the country to

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search alternative new renewable fuels. Green energy is another term for renewable energy

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which is auspicious for alternative, and it is neat and environmentally friendly. As compared

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with fossil energy, green energy produces lower or negligible level of greenhouse gases and

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other pollutants. Emissions like SO2, CO2, and NO2 are lower3,

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renewable energy sources and the production as well as application of green energy plays

4

in comparison to non-



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important role in diminishing the greenhouse impact. Carbon dioxide released from the

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chemical energy obtained from biofuels (via photosynthesis using solar energy) is

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maintaining CO2 levels since green plants are taking the released CO2 from environment.

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Replacing the petroleum fuel, liquid biofuel will be vital in the near future5. Biofuels

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comprise of biodiesel, bio-methanol, bio-ethanol, bio-butanol, vegetable oil, biogas and bio-

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hydrogen. The most important liquid biofuels are biodiesel and bioethanol. Biodiesel is a

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diesel alternative while bioethanol is gasoline substitute. For transportation purpose, liquid

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biofuel have currently drawn attention in number of countries because of their sustainability,

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renewability, bio-degradability and availability, as well as their imminent role in regional

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advancement, inception of rural making job and diminishing the greenhouse gas emissions.

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Oxygen content is the biggest difference between petroleum and biofuel feedstock. Biofuels

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are reliable and are obtained from renewable sources, accessible and sustainable, locally

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available and are non-polluting. Based on their production technology, biofuel can be

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categorized into first-generation biofuels (FGBs), second-generation biofuels (SGBs), third-

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generation biofuels (TGBs)6 and fourth-generation biofuels7.

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Different catalysts are used for synthesis of biodiesel. Most widely used catalysts are

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enzymatic, and acid/base homogeneous and heterogeneous catalysts. Enzymatic catalysts

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have attracted attention as they can withstand free fatty acid and water contents thus assisting

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in purification of biodiesel and glycerol. On the other hand, the enzymztic cztzlysts cannot be

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used commercially as they are costly and show unstable activities with reaction rates much

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lower than homogeneous catalysts8. Common catalysts used for biodiesel synthesis are

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homogenous acid/base catalysts, such as sodium or potassium hydroxide, sodium methoxide,

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sodium ethoxide, sulphuric acid and hydrochloric acid. They have relatively higher kinetic

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rates with high conversion with insignificant side reactions. However, there are numerous

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drawbacks of using them such as corrosive nature, increase in pH of final product9. Removal


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of homogeneous catalysts after transesterification also poses technical problems and large

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amount of wastewater is produced during biodiesel cleaning and separation10. In the

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homogeneous catalytic transesterification, low quality glycerol is produced and thus involves

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meticulous process for purification, catalyst recovery is not possible requiring its

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neutralization at the end of reaction, producing undesired salts which needs to be separated.

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Also, it requires FFA content in feedstock to be less than 3%, so if greater than 3%, it

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necessitates removal of FFAs and moisture. Culminating all these reasons increases the

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processing cost of biodiesel and it’s by products. To settle all these issues, heterogeneous

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catalysts like zeolites, clays, sulfonic ion-exchange resins, pure or mixed oxides,

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heterogenized guanidines, etc.

are being

developed. Heterogeneous catalysts can be

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separated easily and reused, insignificant amount of waste water is produced and separation

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of biodiesel from glycerol is simplified11-12. Reusability of heterogeneous catalysts makes the

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process more economically feasible and also the non-toxic, non-corrosive nature makes the

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process environmentally friendly.

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Previous studies have shown that the fish oil extracted from fish waste13 gave good results for

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the synthesis of biodiesel14. India’s

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9,019,148 tons which includes marine fish production of 3,275,091 tons and inland fish

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production was 5,744,057 tons. During the processing of fish industry, approximately 20-

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80% of fish waste is generated as waste from the total fish weight15. Waste generated from

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fish is used as raw material for the synthesis of biodiesel. In the present work, fish oil has

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been used as raw material for the synthesis of biodiesel since fish market generates huge

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amount of fish waste from which fish oil can be generated16, 17. Fish oil extracted from waste

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not only reduces the amount of waste but also it reduces the amount of total cost of biodiesel

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synthesis. In Indian perspective, it is entirely strenuous to produce biodiesel from the waste

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sources (fish oil extracted from discarded parts of fish and CaO from waste crab shells)

total fish production in the year 2012-2013 was



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because of scarcity of ample feedstock as well as raw material for the catalyst preparation. It

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provides less expensive and more potential option to curtail the overall price of biodiesel

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production. From literature survey, it was clear that very few reports are available on

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transesterification of high acid value feedstocks like fish oil or Millettia pinnata using CaO as

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base heterogeneous catalyst. The present work explores the preparation of waste CaO derived

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from waste crab shells and the efficacy of catalyst in transesterification of fish oil extracted

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from waste parts of fish of Indian origin. The properties of prepared biodiesel were

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considered as per ASTM standards.

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2. EXPERIMENTAL SECTION

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2.1. Material

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The crab shells used for synthesis of the catalyst were collected from Jas Dry Fish

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Merchant-India MART Toothukudi, Tamil Nadu, India. Fish oil was extracted from

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the discarded parts of fish. Methyl alcohol, sulphuric acid, deuterated chloroform

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sodium and sulphate, hexane, toluene, tetrahydrofuran (THF), acetone and diethyl

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ether were of analytical reagent (AR) grade and were purchased from Merck Ltd.,

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Mumbai, India.

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2.2. Fish oil Extraction

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Waste parts of fish such as tails, maw, eyes, viscera, etc. were collected from the local fish

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market (Varanasi), India. The collected discarded parts of fish were washed with hot distilled

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water to eliminate the impurities such as blood and solid particles. Water content of waste

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parts of fish was removed with hot air oven kept at 102 °C for 2 h. Dried waste parts of fish

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were cut into small pieces. Fish oil was extracted from these small pieces through mechanical

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expeller at room temperature. Some amount of oil content still remained in dried matter after

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extraction of fish oil through mechanical expeller. This left amount of oil content was


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extracted through solvent extraction using petroleum ether as solvent. Physical properties of

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waste fish oil such as acid value, density, kinematic victory, boiling point, unsaponifiable

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matter, etc. were determined as shown in Table 1.

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Table 1

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2.3. Catalyst Preparation

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Waste crab shells were dried in a hot air oven at 102 °C for 2 h to remove water content

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present in the waste crab shells. The dried waste crab shells were ground into powder using a

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ball mill. Then the powder was calcined in a muffle furnace at 800 °C for 4 h. The calcined

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material was grounded into fine powder with the help of agate mortar. Catalytic poisoning

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will occur when the catalyst is placed in contact with air because of the presence of moisture

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and carbon dioxide12. Though, the catalytic poisoning was less because of water and carbon

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dioxide, the poisoning was found to be consequential. Therefore, the catalyst was placed in a

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plastic bottle container and then in desiccator to avoid poisoning. The catalyst was

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characterized with various analytical techniques (XRD, FT-IR, TGA/DTA and SEM/EDX)

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and used in the transesterification reactions.

156 157

2.4. Characterization of Biodiesel by Proton NMR Analysis

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The conversion of triglycerides (oil) to fatty acid methyl ester (biodiesel) was analysed using

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proton NMR spectroscopy. The 1H NMR spectrum of biodiesel product is shown in Figure 1.

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A singlet signal at 3.69 ppm represents the methoxy protons of FAME while the triplet at

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2.30 ppm represents α–methylene protons of fatty acid derivatives18-20. The percentage

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conversion of fish oil to biodiesel was calculated by the ratio of integrated signals (area under

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the signal obtained by integration) at 3.69 ppm (AME) and 2.30 ppm (ACH2) in the following

164

equation:



165 166

C = 100(2*XACH3)/(3*ACH2)

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(1)

= 100(2*3)/(3*2.07) = 96.61%

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C denotes the conversion (%) of triglycerides to fatty acid methyl esters; the factors 2 and 3

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in numerator and denominator are ascribed to the number of protons on methylene and

169

number of protons on methyl ester.

170

Figure 1

171 172

2.5. Gas Chromatography–Mass Spectrometry (GC-MS) Analysis

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Fish oil methyl esters were analysed with the Gas Chromatography Mass Spectrometry (GC-

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Mass Spectrometer Perkin Elmer, Mass range: 20 to 620 Daltons (amu)). Samples were

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prepared to analyse when 0.03 mL of fish oil methyl esters were mixed with 2.1 mL of

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hexane. Figure 2 represents the GC-MS chromatogram in which X-axis corresponds to

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retention time and Y-axis corresponds to parentage of relative abundant. Using the known

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compound spectrum from the NIST 2011 library, unknown compound spectrum was

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predicted with the help of Turbo Mass software. The major fish oil methyl esters were

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Myristic acid methyl ester (5.51%), Palmitoleic acid methyl ester (9.70%), Palmitic acid

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methyl ester (14.09%), Arachidonic acid methyl ester (3.21%), Oleic acid methyl ester

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(11.03%), Linolenic acid methyl ester (3.45%), Stearic acid methyl ester (4.05%),

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Eicosapentaenoic acid methyl ester (EPA) (19.96%), Docosahexaenoic acid methyl ester

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(DHA) (13.93%) and Erucic acid methyl ester (1.08%) were shown in Table 2.

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Figure 2

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Table 2

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2.6. FT-IR analysis of biodiesel

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Purified biodiesel was characterized with FT-IR spectroscopy as shown in Figure 3. Sharp

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band was observed at 1742 cm-1 is attributed to C=O stretching frequency and another sharp 8 ACS Paragon Plus Environment

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band observed at 2923 cm-1 is assigned to C-H stretching vibration of methylene groups.

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Sharp absorption band at 1459 cm-1 is due to asymmetric CH2 bending vibrations. The band

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at 1160 cm-1 is due to C-O stretching frequency of fatty acid methyl of ester.

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Figure 3

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2.7. Esterification

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Acid value determination of the feedstock was determined prior to transesterification process.

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Acid value determines whether the esterification step is required or not. The important

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parameters for determining the viability of the transesterification is free fatty acid content

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present in the raw fish oil21. The FAME conversion is inversely proportional to the acid value

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of the oil in base catalyzed biodiesel synthesis, reason for this is the soap formation with the

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acid of the base catalyst. In present case, acid value of the feedstock was found to be 11.89

201

which is quite high and acid

202

corresponding FAME’s. In acid esterification, fish oil: methanol (1:8) molar ratio was poured

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in a indigenously fabricated 3 necked round bottom flask and 1% (v/v) of sulphuric acid was

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added to it and the content was mechanically agitated on a water bath at 60 oC. Esterification

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reaction was completed in 120 min. After completion of the reaction, the reaction mixture

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was poured in a separating funnel followed by rotavapor separation. After esterification, acid

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value was reduced to less than 2 ± 0.25 mg KOH/g and it was subjected to transesterification

208

reaction.

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Acid value of the feedstock and biodiesel was calculated using following equation:

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Acid Value (mg KOH/g) = VKOH *56.1*CKOH / msample

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FAME’s conversion was calculated using following eq 1.

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Free Fatty Acid Conversion (%) = (AV1-AV2)/AV1*100

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Where AV1 (mg KOH g-1) is the acid value of original oil sample, and AV2 (mg KOH

214

g-1) is the acid value of catalysed product.

esterification was performed

to convert FFA’s into

(2)

(3)



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215 216 217

2.8. Transesterification

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After esterification, transesterification reactions were conducted using calcium oxide catalyst

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derived

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transesterification reactor with 250 mL three-neck round bottom flask.

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with an overhead mechanical stirrer and water-cooled reflux condenser. The parameters such

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as molar ratio of oil: methanol (varied from 1:4 to 1: 14), catalyst loading (varied from 1% to

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3%), stirrer speed (350 rpm to 850 rpm), reaction temperature (varied from 35 °C to 85 °C)

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and reaction time (varied from 30 to 130 min) were studied. In each and every experiment,

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co-solvent: methanol (1:1) was added. After completion of each experiment, biodiesel was

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separated using separating funnel followed by rotavapor. Biodiesel was characterized with

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FT-IR, and 1H NMR.

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3. RESULTS AND DISCUSSION

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The prepared catalyst was characterized by Differential Thermal Analysis/Thermo

230

Gravimetric

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Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDX) and Fourier Transform

232

Infrared Spectroscopy (FT-IR).

233

3.1. XRD Analysis

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The powder X-ray diffraction (XRD) analysis was carried out with a Shimadzu

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diffractometer model XRD 6000. The diffractometer employed Cu-Kα radiation to generate

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diffraction patterns from the powder crystalline samples at ambient temperature. The Cu-Kα

237

radiation was generated by a Philips glass diffraction X-ray tube (broad focus 2.7 kW type).

238

The XRD diffraction spectra of the calcium oxide derived from white wash as shown in

239

Figure 4. The appearance of calcium oxide peaks derived from waste crab shells in XRD

from

waste

Analysis

crab

shells.

(DTA/TGA),

All

the

X-ray

experiments

Diffraction

were

(XRD),

carried It

Scanning

out

in a

is fitted

Electron


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indicated that the pure calcium oxide was formed when the complete conversion of calcium

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carbonate into calcium oxide by releasing carbon dioxide. The peaks were matched with the

242

Joint Committee on Powder Diffraction Standards (JCPDS) files. The peaks observed at

243

32.2°, 37.3°, 53.8°, 67.3°, and 79.6° (JCPDS 48-1467) of X-ray diffraction tell us the

244

presence of the calcium oxide having the face-centered lattice.

245

Figure 4

246

3.2. SEM analysis

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The surface morphology of calcium oxide derived from waste crab shells were observed

248

using Scanning Electron Microscope (SEM). Figure 5 represents the scanning electron

249

microscope images showing the surface morphology of the calcium oxide catalyst. The

250

image was taken at various magnifications and at a voltage of 20 kV. The particles are

251

agglomerated due to the precursor's high temperature of calcination. If we plot frequency of

252

the particle vs. size, it reveals that the size of the particles varied between 1.2–2.5 µm but

253

most of them were in 1.6–2 µm range.

254

Figure 5

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3.3. Energy dispersive X-ray spectroscopy

256

Energy dispersive X-ray spectroscopy is a well-known analytical procedure to determine the

257

elemental or the chemical composition of the calcium oxide derived from waste crab shells.

258

No peaks of carbon were observed in the EDX spectrum. It showed the complete conversion

259

of calcium carbonate present in the crab shells into calcium oxide by releasing carbon dioxide

260

as shown in Figure 6. The percentage weight of Ca inferred from studying EDX spectrum

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was 53.21 and oxygen was 46.79 as shown in the Table 3. The atomic percentage of Ca was

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68.78 and oxygen was 31.22.

263

Figure 6

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Table 3 11 ACS Paragon Plus Environment


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3.4. TGA/DTA analysis

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Figure 7 represents the Thermo Gravimetric Analysis (TGA)/ Differential Thermal Analysis

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(DTA) of un-calcined waste crab shells. 10 mg of sample is taken and kept in a 1 ml

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aluminum crucible with heating rate of 10 °C/ min at 50 ml/min air flow rate. Pure aluminum

269

powder was taken as reference material. It has been observed that the weight loss of the un-

270

calcined waste crab shells occurred from 27 °C to 770 °C. The total weight loss of un-

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calcined waste crab shells were found to be 52.7%. Weight loss (5.41%) in TGA curve under

272

0 < T >200 was due to the removal of water content present in the un-calcind waste crab

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shells and further weight loss (7.2%) observed at 200500 was due to the loss of some

274

amount of organic compounds present in the un-calcined waste crab shells. Sharp weight loss

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(41.08%) was occurred under 500789 is due to the complete conversion of calcium

276

carbonate into calcium oxide by releasing carbon dioxide, further there was no significance

277

weight loss since stable calcium oxide formation had taken place.

278

Figure 7

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3.5. FT-IR analysis

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Figure 8 shows the Fourier transform Infrared (FT-IR) spectra of calcined crab shells 800 °C.

281

FT-IR spectra of calcined crab shells shows major absorption band at band at 506 cm-1 is

282

characteristic of Ca-O bond9. The absorption band at 1083 cm-1 and symmetric stretching

283

vibration band at 1483 cm-1 is corresponding to insignificant amount of carbonate (CO3-2)

284

present in the catalyst derived from the waste crab shells. The FT-IR absorption band at 3646

285

cm-1 indicates the existence of -OH stretching vibration because of water molecule present on

286

the surface of CaO catalyst.

287

Figure 8

288

3.6. Brunauer – Emmett – Teller (BET) surface area of CaO


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Figure 9 represents the Brunauer–Emmett–Teller (BET) surface area of CaO derived from

290

crab shells. BET of CaO was measured with nitrogen gas adsorption–desorption isotherms at

291

– 196 °C. The surface area of CaO derived from crab shells was 16.01 m2/g which was

292

calculated from the isotherm linear plot drawn in between relative pressure (P/Po) vs quantity

293

of nitrogen adsorbed (cm3/g STP). According to previous work, calcium oxide (CaO) derived

294

from pulverized lime stone was found to have a surface area 13.00 m2/g which is slightly

295

lesser than that found in the present work (calcium oxide derived from crab shells). This high

296

surface area of CaO derived from crab shells is its one of the major advantages that facilitated

297

calcium oxide to be a good catalyst in the transesterification. The pore volume and average

298

pore width of catalyst were 0.03013 cm3 /g, 73.6034 Å respectively.

299

Figure 9

300

3.7. Effect of reaction parameters on biodiesel yield

301

To optimise biodiesel production, the effect on biodiesel yield due to various parameters viz.

302

catalyst loading, oil-to-methanol molar ratio, reaction time, reaction temperature and stirrer

303

speed were studied. The effect of co-solvent22 (tetrahydrofuran) on the yield was also

304

investigated. In heterogeneous transesterification process, the reaction mixture constitutes a

305

3-phase system due to presence of solid catalyst, methanol and oil phases, which cause

306

mixing problems. The co-solvent increases the mutual solubility of oil23 and methanol

307

resulting in better mass-transfer. Consequently, we get higher initial reaction rates, shorter

308

reaction time and better yield. The catalyst loading was studied in the range of 1% to 3%.

309

Oil-to-methanol molar ratio was varied from 1:4 to 1:14. Co-solvent was kept proportionate

310

to methanol was (1:1). Reaction time was varied from 30 to 130 minutes; the reaction

311

temperature was varied from 35 °C to 85 °C; and stirrer speed was varied from 350 to 850

312

rpm.

313



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3.8. Effect of catalyst loading on biodiesel yield

315

A series of experiments was carried out at different catalyst loadings and at different oil to

316

methanol ratios keeping other parameters constant. The loading of catalyst was varied from 1

317

to 3 wt% and oil to methanol molar ratio from 1:4 and 1:14. Figure 10 represents the

318

combined effect of catalyst loading and ‘oil: methanol molar ratio’ on biodiesel yield with

319

and without addition of the co-solvent. As the results illustrates, there was a significant and

320

sharp improvement in biodiesel yield by increasing loading of catalyst up to 2.5 wt%.

321

Maximum biodiesel yield (96 %) was obtained at 2.5 wt% with the addition of co-solvent.

322

Oil mixed with methanol forms a well dispersed emulsion and sufficient amount of catalyst

323

provides a proper contact which leads to reactions resulting in high yield of biodiesel24 and

324

beyond 2.5 wt% of catalyst, there was no significant increase in biodiesel yield. This could be

325

attributed to the fact that catalyst makes the reaction mixture more viscous which causing

326

difficulty in mass transfer25. Transesterification of triglycerides is a reversible process, excess

327

quantities of methanol facilitate biodiesel conversion26 since methanol molecules will contact

328

easily with triglycerides. Pure and high yield (96%) occurred at oil to methanol ratio of 1:10

329

beyond which yield starts stagnating or ebbing. The high molar ratio of methanol interferes

330

with the separation of glycerol. The glycerol produced in the reaction diffuses in excess

331

methanol and remains in the solution, driving back the reversible reaction and lowering the

332

yield27. Moreover, in each experiment, it was also observed that addition of co-solvent

333

contributes significantly to an increase in yield.

334

Figure 10

335

3.9. Effect of reaction temperature on biodiesel yield

336

The transesterification of fish oil using 2.5 wt% of CaO catalyst was performed at 35 °C to

337

85 °C temperatures with an oil to methanol ratio of 1:10, reaction time 90 min at a stirrer

338

speed of 650 rpm. Figure 11 represents the effect of temperature on the biodiesel yield with 14 ACS Paragon Plus Environment

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and without addition of the co-solvent. There was a gradual increase in biodiesel yield on

340

increasing the temperature from 35 °C up to 65 °C. The optimum temperature was found to

341

be 65 °C with the addition of co-solvent since high biodiesel yield occurred at this

342

temperature. Due to high viscosity of oils, methanolysis is usually performed near the boiling

343

point of methanol (65 °C) to decrease viscosity, enhance mass transfer and increase reactivity

344

of reactants28. Temperature has a significant effect on the reaction rate but after a threshold

345

temperature (65 °C) the biodiesel yield starts decreasing. On increasing temperature beyond

346

65 °C, no significant effect on biodiesel yield was observed, rather the yield was decreased to

347

some extent. This may be due to vaporisation of methanol which lead to reduced contact with

348

the reactants.

349

Figure 11

350

3.10. Effect of reaction time on biodiesel yield

351

Reaction time required for transesterification depends on the reaction temperature as well as

352

on degree of mixing29. Experiments were conducted by varying the reaction time in the range

353

of 30 to 130 min. at catalyst loading of 2.5 wt%, reaction temperature of 65 °C, oil-to-

354

methanol ratio of 1:10, and a stirrer speed of 650 rpm. Figure 12 represents the effect of

355

reaction time on biodiesel yield with and without addition of co-solvent. The yield showed

356

improvement upon increasing the reaction time up to 90 min. Increasing the time beyond 90

357

min led to a slight decrease in yield. This is because longer reaction time favours reverse

358

reaction of hydrolysis of esters along with soap formation from fatty acids30. Hence,

359

controlling reaction time is critical for enhancing yield. The optimal reaction time for

360

transesterification of fish oil was found to be 90 min at 65 °C and 650 rpm along with the

361

addition of co-solvent. Moreover, the presence of co-solvent was found to increase yield for

362

all of the tested reactions.



Page 16 of 44

363

Figure 12

364

3.11. Effect of stirrer speed on biodiesel yield

365

Mixing is important in transesterification reactions since oils and fats are immiscible in solid

366

catalysts and partially soluble in alcohol. Experiments were conducted in which stirrer speed

367

was varied between 350 rpm to 850 rpm while other parameters were kept constant: the

368

catalyst loading was kept at 2.5 wt%, oil-to-methanol ratio at 1:10 and reaction temperature at

369

65 °C for 90 min. Figure 13 represents the effect of stirrer speed on biodiesel yield with and

370

without addition of co-solvent. Initially, there is a significant increase in yield on increasing

371

stirrer speed. This is because the reaction mixture exists in two phases and the agitation helps

372

to intersperse oil and methanol leading to relative homogenisation and greater contact

373

between reactants. High biodiesel yield, 95%, occurred at the optimum stirrer speed 650 ppm.

374

Increasing the stirring beyond the optimum value lead to no significant increase in yield due

375

to vaporisation of methanol reducing its contact with other reactants. In each experiment, it

376

was found that the addition of co-solvent gave a higher yield. The presence of co-solvent

377

accelerates the homogenisation of the two-phase system into a single phase. Consequently, it

378

helps in higher yield of biodiesel at minimum stirrer speed.

379

Figure 13

380

3.12. Effect of co-solvent on biodiesel

381

Effect of co-solvent on biodiesel yield was observed by taking different co-solvents such as

382

toluene, and diethyl ether, hexane, tetrahydrofuran (THF) and acetone as shown in Figure 14.

383

Co-solvent to methanol molar ratio fixed at 1:1 while other factors such as methanol: oil

384

(1:10), reaction temperature (65 °C), stirrer speed (650 rpm) and catalyst loading (2.5%) were

385

kept constant. Reaction mixture exists as two phase system in which methanol exhibited


Page 17 of 44


386

hydrophilic nature and fish oil exhibited hydrophobic nature. This immiscibility between

387

alcohol and oil can be reduced by using co-solvents31, 32 to drive the reaction mixture towards

388

the product side. Molar ratio (methanol: oil) of reaction mixture is more important factor for

389

the production of biodiesel since transesterification process is reversible33, to shift the

390

reaction to product side we need to use more amount of methanol in reaction mixture. Instead

391

of using more amount of methanol, co-solvent was added to reaction mixture which not only

392

reduced the amount of methanol but also other factors such as reaction time reaction

393

temperature stirrer speed, etc. Among all the co-solvents, the biodiesel yield (95%) was

394

highest in the case of THF. Tetrahydrofuran (THF) facilitates the reaction mixture (oil phase

395

and alcohol phase) to more homogeneous and also it reduced the energy consumption. So, we

396

selected THF as co-solvent for the synthesis of biodiesel. Optimization of THF determined

397

and was found maximum at 1:1 (co-solvent: alcohol) as shown in Figure 15.

398

Figure 14

399

Figure 15

400

3.13. Separation and purification

401

Reaction mixture was poured into a separating funnel after completion of transesterification

402

reaction to separate biodiesel from its by-products. Biodiesel was taken out from the

403

separating funnel after clear separation through the gravity, and was washed with hot distilled

404

water. Water remained after washing was removed with rotavapour and centrifuged to

405

remove trace amount of solid particles presents in the biodiesel. Thereafter, each and every

406

characterization of biodiesel was done according to ASTM standards. Physical and chemical

407

properties of synthesized biodiesel were provided in Table 4 and found that the density was

408

reduced from 0. 0.899 (waste fish oil) to 0. 869 (biodiesel), flash point was reduced from 270

409

(waste fish oil) to 150 (biodiesel) and pour point was reduced from 13 (waste fish oil) to 17 ACS Paragon Plus Environment


Page 18 of 44

410

1.02(biodiesel). Kinematic viscosity (at 40 °C) of was reduced 25.51 (waste fish oil) to 4.99

411

(biodiesel) since density is directly proportional to viscosity. Calorific value of synthesized

412

biodiesel was 9650 cal/g and the moisture content was found to be 0.001%. This synthesized

413

biodiesel was checked with copper strip and no corrosion was observed. Calcium oxide

414

derived from waste crab shells delivered good results for the synthesis of biodiesel when

415

compared with other catalysts which were derived from waste materials as shown in Table 5.

416

Table 4

417

Table 5

418

3.14. Reusability and leaching property of catalyst

419

Leaching effect of calcium oxide CaO derived from waste crab shells catalyst was

420

determined in synthesized biodiesel using waste fish oil. It was ratified by elemental analysis

421

using SEM/EDS analysis after completion of the reaction. It was revealed that there was no

422

change in calcium and oxygen amount.

423

conducted34 and no catalyst leaching was observed. After separation of methanol, catalyst

424

was used in transesterification reaction and found that there was no change in its activity35.

425

After washing with methanol, catalyst was reused by two manners. In first process catalyst

426

was calcined at 750˚C and reused up to 5 runs and in second process reused without

427

calcination up to 5 runs as shown in Figure 16. Calcined catalyst gave more conversion than

428

one without calcination. Consequently, it was inferred that calcination provided better

429

activity of the sites of catalyst and hence amended the biodiesel production.

430

Figure 16

431

4. CONCLUSION

432

Biodiesel was synthesized from waste fish oil through esterification and transesterification

433

reactions. A novel heterogeneous solid base catalyst (calcium oxide (CaO)) was derived

434

from waste crab shells and characterized with SEM-EDX, XRD, FTIR, and TGA/DTA.

Further examination of catalyst leaching was


Page 19 of 44


435

Synthesized biodiesel was characterized with the proton NMR and FT-IR. Free fatty acid

436

composition of waste fish oil was determined using GC-MS. Effect of various parameters

437

such as stirrer speed, temperature of the reaction, reaction time, and catalyst loading on

438

biodiesel conversion and yield were studied. Effect of co-solvent on biodiesel was further

439

studied by using different solvents such as toluene, and diethyl ether, hexane,

440

tetrahydrofuran (THF) and acetone. High yield 96.6% and pure biodiesel was obtained

441

when 2.5 wt% of synthesized catalyst, 1:12 oil: methanol molar ratio at 65 °C for 90min.

442

Reusability of catalyst up-to five times without loss of activity was observed. No catalyst

443

leachability was observed in transesterification reactions. The qualities of biodiesel were

444

ascertained as per ASTM biodiesel standard and obtained nearly to specification.

445

ACKNOWLEDGMENTS

446

The authors acknowledge the support of Central Instrument Facilities, Indian Institute of

447

Technology (BHU), India and also authors thankful to Institute for supporting financial

448

assistantship through the Institute Fellowship. Authors also acknowledge the financial

449

assistance from DST as DST- IBSA project (GP/LT/Chemistry/15-16-01).

450

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Zhang, Y.; Dube, M.; McLean, D.; Kates, M., Biodiesel production from waste cooking oil:

Sarma, A. K.; Sarmah, J. K.; Barbora, L.; Kalita, P.; Chatterjee, S.; Mahanta, P.; Goswami,

Lee, J.-S.; Saka, S., Biodiesel production by heterogeneous catalysts and supercritical

Yahyaee, R.; Ghobadian, B.; Najafi, G., Waste fish oil biodiesel as a source of renewable fuel

Costa, J.; Almeida, M.; Alvim-Ferraz, M.; Dias, J., Biodiesel production using oil from fish

Ghaly, A.; Ramakrishnan, V.; Brooks, M.; Budge, S.; Dave, D., Fish processing wastes as a

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scale collagen in food and agriculture industries. Biocatal. Agr. Biotechnol. 2016, 7, 234.

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Tabernaemontana divaricata seed oil. J. Chem. Pharm. Res. 2013, 5, (1), 172.

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secondary sludge. Bioresource Technol. 2016, 216, 165.

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transesterification of refined palm oil in supercritical methanol. Eng. J. 2011, 15, (3), 49.

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solvent on biodiesel production by supercritical methanol reaction. J. Super. Crit. Fluid. 2010, 53, (1),

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88.

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value by magnetic Na 2 SiO 3@ Fe 3 O 4/C catalyst and ultrasound. Fuel 2015, 150, 370.

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rapeseed oil over modified CaO. Appl. Energ. 2011, 88, (8), 2735.

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heterogeneous catalyst for biodiesel production from soybean oil and waste frying oil. Energ.

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Convers. Manage. 2015, 89, 665.

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transesterification—a review. Renew. Sust. Energy. Rev. 2006, 10, (3), 248.

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Basumatary, S.; Barua, P.; Deka, D., Identification of chemical composition of biodiesel from

Kumar, M.; Ghosh, P.; Khosla, K.; Thakur, I. S., Biodiesel production from municipal

Canacki, M.; Gerpen, J. V., Biodiesel production via acid catalysis. T. Am. Soc. Agr. Eng.

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Tan, K. T.; Lee, K. T.; Mohamed, A. R., Effects of free fatty acids, water content and co-

Zhang, F.; Fang, Z.; Wang, Y.-T., Biodiesel production directly from oils with high acid

Tang, Y.; Meng, M.; Zhang, J.; Lu, Y., RETRACTED: efficient preparation of biodiesel from

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production. Fuel Pocess. Technol. 2006, 87, (10), 883.

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biodiesel production from waste canola oil. Afr. J. Agr. Res. 2010, 5, (14), 1851.

520

31.

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conditions for esterification of fatty acids with alcohols. Ind. Eng. Chem. Res. 2013, 52, (3), 1205.

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32.

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Production of biodiesel from Vietnamese Jatropha curcas oil by a co-solvent method. Bioresource

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Technol. 2014, 173, 309.

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526

the use of co-solvents to produce biodiesel. Fuel 2016, 166, 51.

527

34.

528

CaO from different sources as a catalyst precursor in soybean oil transesterification: Kinetics and

529

leaching evaluation. J. Environ. Chem. Eng. 2016, 4, (2), 1970.

530

35.

531

curcas oil into biodiesel using re-crystallized hydrotalcite. Energ. Convers. Manage. 2013, 73, 128.

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Encinar, J. M.; Pardal, A.; Sánchez, N., An improvement to the transesterification process by

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532 533

Graphical abstract


Page 23 of 44


534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551

Table 1. Physical and Chemical Properties of Waste fish oil. 23 ACS Paragon Plus Environment


Property

Unit -

Color Acid value

ASTM Standards

mg

Page 24 of 44

Value Yellowish red

ASTM D 664

11.89

KOH/g Unsaponifiable matter

% w/w

ASTM D1065

0.78

Density at 15.5 °C

g/cm3

ASTM D 1298

0.899

Boiling point

°C

-

> 356

Cloud point

°C

ASTM D 1510

13

Saponification value

mg

187

KOH/g Pour point

°C

Kinematic viscosity, at 40 mm2/s

ASTM D 97

-1

ASTM D 445

25.51

°C Flash point

°C

ASTM D 93

270

Water content

in%

ASTM D 2709

0.009%

Iodine value

-

ASTM D 2500

110

Copper strip corrosion

-

ASTM D 130

No Corrosion observed

552 553 554 555 556 557 558 559 560 24 ACS Paragon Plus Environment

Page 25 of 44


561 562

Table 2. Free Fatty Acids and their Composition (%) of Waste fish oil. Sr. Retention

Compound name

Composi Correspondi

Corresponding

tion (%)

ng fatty acid

strucure

Myristic acid

CH3(CH2)12COOH

Palmitoleic

CH₃(CH₂)5CH=CH(CH₂)₇CO

methyl ester

acid

OH

Palmitic acid methyl 14.09

Palmitic acid

CH3(CH2)12COOH

Arachidonic

CH3(CH2)10(CH=CH)4COOH

time 1

17.37

Myristic acid methyl 5.51

fatty

acid

ester 2

3

19.32

19.55

Palmitoleic

acid 9.70

ester 4

21.06

Arachidonic

acid 3.21

methyl ester 5

21.25

Oleic

acid

acid methyl 11.03

Oleic acid

CH3(CH2)14CH=CHCOOH

Linoleic acid


Stearic acid

CH3(CH2)16COOH

Eicosapentaenoic acid 19.96

Eicosapentae


methyl ester (EPA)

noic acid

Docosahexaenoic acid 13.93

Docosahexae

methyl ester (DHA)

noic acid

Erucic

Erucic acid

ester 6

21.29

Linoleic acid methyl 3.45 ester

7

21.46

Stearic

acid

methyl 4.05

ester 8

9

10

22.77

24.33

24.66

acid

methyl 1.08


CH3(CH2)18(CH=CH)COOH

ester 563



Page 26 of 44

564 565

Table 3. Elemental Composition of Calcium oxide (weight% and atomic %) by EDS

566

Analysis.

567 568 569 570 571

Element Weight%

Atomic%

O

46.79

68.78

Ca

53.21

31.22

Total

100.00

572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 26 ACS Paragon Plus Environment

Page 27 of 44


591 592

Table 4. Physical and Chemical Properties of Waste fish oil Biodiesel.

Property

Unit

ASTM

Value

Standards -

Color Acid value

mg

Yellowish red ASTM D 664

1.78

KOH/g Density @15.5 °C

g/cm3

ASTM D 1298

0.869

Boiling point

°C

-

356

Cloud point

°C

ASTM D 1510

1.02

Pour point

°C

ASTM D 97

-1

Kinematic viscosit, at 40 °C

mm2/s

ASTM D 445

4.99

Flash point

°C

ASTM D 93

150

ASTM D613

Cetane number Calorific value

cal/g

ASTM D 4809

9650

Water content

in%

ASTM D 2709

0.001%

Copper strip corrosion

-

ASTM D 130

No Corrosion observed

593 594 595 596 597 598 599 600 27 ACS Paragon Plus Environment


Page 28 of 44

601 602 603 604

Table 5 Represents the Summary of Different Kinds of Waste Catalysts used in the

605

Synthesis of Biodiesel. Cataly st

CaO CaO CaO

CaO CaMg( CO3)2 KAl(S O4)2 K2O βCa3(P O4)2 Hydrox yapatite

Waste material

Reaction conditions

Catalyst amount (wt.%) Crab shells 2.5 Snail Mollusc 2 shells Exoskeleton 4 (Pila globosa) Mollusc shells Chicken egg 3 shells Dolomite 3

Methanol to oil molar ratio 12:1 6:1

Reaction temperat ure (°C) 65 60

10:1

Alum

Conversion (C) or Yield Reaction (Y) time (h) 1.5 8

Y = 96.6 % C = 99.58 %

60

5

C = 97.8 %

9:1

65

3

Y = 95 %

6:1

67.5

3

Y = 91.8 %

7.09

18:1

170

12

Y = 92.5 %

Coal fly ash 15 loaded KNO3 Rohu fish 1.01 (Labeo rohita) bone Sheep bone 20

15:1

70

8

C = 87.5 %

6.27:1

70

5

Y = 97.7 %

18:1

65

4

C = 96.78 %

606 607 608 609 610


Page 29 of 44


611 612 613

614 615

Figure 1. NMR Spectrum of Biodiesel synthesized from waste fish oil

616 617 618 619 620 621 622 623 624 625 626



Page 30 of 44

627 628 629

630 631 632

Figure 2. GC-MS analysis and identification of fatty acid methyl ester

composition in

waste fish oil

633 634 635 636 637 638


Page 31 of 44


639 640 641

642 643

Figure 3. FT-IR Spectrum of synthesized biodiesel from waste fish oil

644 645 646 647 648 649 650 651 652 653 654 655



Page 32 of 44

656 657 658

659 660

Figure 4. XRD patterns of calcium oxide derived from waste crab shells

661 662 663 664 665 666 667 668 669 670 671 672


Page 33 of 44


673 674 675

676 677

Figure 5. SEM of calcium oxide catalyst derived from waste crab shells

678 679 680 681 682 683 684 685 686 687 688 33 ACS Paragon Plus Environment


Page 34 of 44

689 690 691 692

693

Figure 6. EDX spectrum of calcium oxide derived from waste crab shells

694 695 696 697 698 699 700 701 702 703 704


Page 35 of 44


705 706

707 708

Figure 7. TGA/DTA of uncalcined waste crab shells

709 710 711 712 713 714 715 716 717 718 719 720



Page 36 of 44

721 722

723 724

Figure 8. FT-IR Spectrum of calcium oxide derived from crab shells

725 726 727 728 729 730 731 732 733 734 735 736


Page 37 of 44


737 738

739 740

Figure 9. BET of calcium oxide (CaO) derived from waste crab shells

741 742 743 744 745 746 747 748 749 750 751 752 753 37 ACS Paragon Plus Environment


Page 38 of 44

754

755 756

Figure 10. Effect of catalyst loading on biodiesel yield

757 758 759 760 761 762 763 764 765 766 767


Page 39 of 44


768 769

Figure 11. Effect of reaction temperature on biodiesel yield

770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 39 ACS Paragon Plus Environment


Page 40 of 44

786 787 788 789 790 791 792 793 794 795 796 797

Figure 12. Effect of reaction time on biodiesel yield

798 799 800 801 802 803 804 805 806 807 808 809


Page 41 of 44


810 811

Figure 13. Effect of agitation speed on biodiesel yield

812 813 814 815 816 817 818 819 820 821 822 823 824



Page 42 of 44

825 826

Figure 14. Represents the effect of co-solvents on biodiesel yield

827 828 829 830 831 832 833 834 835 836 837 838 839


Page 43 of 44


840 841

Figure 15. Optimization of THF (Co-solvent) with Methanol (Solvent)

842 843 844 845 846 847 848 849 850 851 852 853 854 855 856



Page 44 of 44

857 858

Figure 16. Reusability of catalyst with and without calcination


Synthesis of High-Quality Biodiesel Using Feedstock and Catalyst

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