Now biodiesel has become a long-term viable option while being a gentler-on-the-planet on the planet alternative to conventional fossil fuels, offering lessened release of greenhouse gases and biodegradability. The focus of this research is on the production of biodiesel from both used vegetable oil (UVO) and raw vegetable oils through transesterification, a process that converts triglycerides into fructooligosaccharide methyl esters using alcohol (typically methanol) and a catalyst. The research compares the efficiency, yield, and quality used to make biodiesel from used cooking oil and fresh vegetable oils, highlighting the economic and environmental benefits of utilizing waste oils. Key parameters such as oil reacting temperature, composition, free fatty acid content, catalyst type, and alcohol-to-oil ratio were analyzed to optimize biodiesel production. The results demonstrate that biodiesel derived from used vegetable oil presents a viable alternative with comparable fuel properties to that produced from raw vegetable oils while promoting waste recycling and cost-effectiveness. The findings of this research reinforce the possibilities of biodiesel as an alternative fuel and support its role in sustainable energy development.

Excerpt

Abstract

1. Introduction
1.1. General Introduction
1.2. Research Motivation
1.3. Aims and Objectives

2. Literature review.
2.1. Review of Earlier Work
2.1.1. Low-Cost Feedstock
2.1.2. Chemical Structure of Oils
2.1.3. Procedure Adopted for Biodiesel Production
2.1.4. Transesterification
2.1.5. Process Parameters for Biodiesel Production via Transesterification
2.1.6. Transesterification for Changes in Process Parameters
2.1.7. Optimization of Process Parameters of Biodiesel Production
2.1.8. Qualitative Analysis of Biodiesel

3.1. Materials Used for Biodiesel Production
3.2. Steps to be followed for Biodiesel Production
3.2.1. Pre-processing of the Feedstock
3.2.2. Estimation of the FFA content
3.2.3. Free Fatty Acid Estimation of the Oil
3.2.4. Calculation of the Amount of Catalyst
3.2.5. Calculation of the Amount of Alcohol
3.2.6. Acid Esterification
3.2.7. Mixing and Neutralization
3.2.8. Transesterification
3.2.9. Separation
3.2.10. Purification of Crude Biodiesel by Water Washing
3.3. Apparatus Used for Measurement of Different Properties of Biodiesel
3.3.1. Estimation of Density
3.3.2. Flash Point and Fire Point
3.3.3. Estimation of Viscosity
3.3.4. Estimation of Calorific Value

4. Results & discussion
4.1. Results-
4.1.1. Yield of Biodiesel
4.1.2. Estimation of Properties of Biodiesel Prepared from Used Vegetable Oils and Raw Oils
4.2 Discussion

5. Conclusions

6. References

7. List of figures

Abstract

1. Introduction

1.1. General Introduction

Both environmental degradation and the exhaustion of fossil resources are pressing global concerns. The reckless usage and exploitation of fossil fuels have drained petroleum reserves. Fuels derived from petroleum have limited supplies. There is just one region of the world where these few deposits are concentrated. Consequently, nations that lack assets are confronted with a severe shortage of foreign currency, mostly because of the import of petroleum crude. According to Singh S.P. and Singh D., it is crucial to look for alternative fuels that may be made utilizing materials that are available locally [1]. Fuel supplies are dwindling at an alarming rate, prompting research into plant-based alternatives [2]. The fast increase in energy consumption due to rising populations, better living standards, and more economic activity has led to enormous emissions of greenhouse gases (GHGs), as stated in the 2016 World Oil Outlook report. By 2040, the world will be using 109.4 million barrels of fuel oil per day, according to the same estimate. A scarcity of resources and the negative impact on the environment are two major obstacles to meeting the rising demand for oil fuel.

Due to its widespread use in land, air, and sea transportation as well as in power plants, buildings, and industrial activities, petroleum oil is widely acknowledged as the second most used energy resource. Due to diesel engines' greater efficiency compared to other internal combustion engines, diesel fuel is consumed at a higher rate than other gasoline products [3]. Consequently, several studies sought to find alternatives to fossil diesel fuels, such as renewable energy sources. According to research by Lin et al., Rudolf Diesel showcased a peanut oil–powered diesel engine at the 1900 World Exhibition [4]. According to Elkelawy et al., researchers have been compelled to find a renewable, energy-efficient, and environmentally friendly alternative to diesel due to growing concerns about environmental degradation [5. The transportation industry ranks second in our country for energy consumption, according to research by Rajkumar and Thangaraja [6]. The most important things to keep in mind are the harmful emissions of smoke and oxides of nitrogen. In 2022, India will be the world's third-largest importer of crude oil, according to Workman. A staggering USD 119.2 billion was spent by India on the import of crude oil in the fiscal year (2021–2022), according to the Economic Times of 2022, putting a significant strain on our nation's economy. Crude oil combustion also adds to greenhouse gas emissions and air pollution.

The graph shown in Fig. 1.1 from CEIC, 2022 shows the import of crude oil in terms of barrels per day from 2010 to 2021 in India. The X-axis denotes the year, and the Y-axis denotes the barrels/day imported into India.

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Fig: 1.1. Import of crude oil by India (barrel/day) [CEIC, stands in the context of crude oil and economics, 2022]

A report by International Energy Agency, 2009, suggests that 2005, India utilized 30 million tonnes of oil in the transportation industry in 2005, with petrol accounting for 29% and diesel accounting for 71%. According to Gonsalves, Indian energy consumption is predicted to expand at a 4.8% annual pace over the next two decades [7]. Many possibilities predict that India's oil consumption will be more than triple by 2030. According to Hindustan Times, 2022, the provisional data of the Petroleum Planning and Analysis Cell, India reported that in 2019-20, India's total petroleum consumption was 194.3 million metric tons. An article states that by the International Energy Agency (2006), the consumption of biofuels has been speculated to reach 92.4 megatonnes of oil equivalent by 2030. World Oil Outlook, 2016, reported that according to the Government of India's Ministry of Railways, Indian Railways utilize more than two billion gallons of diesel every year. The Ministry also adds that a slight reduction in diesel usage through biodiesel blending can result in significant fuel savings, as well as the benefits of a cleaner environment owing to fewer carbon emissions. Dhaker Abbes et al. stated that the alternative renewable fuel that comes under light is biodiesel [8]. Biodiesel is derived from the oil extract of plants or fats of animals. It is an alternative to diesel and can also be used as a fuel additive.

Biodiesel in India is made mostly from non-edible oil seeds using an indigenous process, according to comprehensive research by Neelima Mahato et al., 2015 [9]. In addition to being sulfur-free, bio-diesel is non-toxic and biodegradable. The annual production capacity of biodiesel from tree-borne oil seeds is around 20 million metric tons. Although approximately 20% to 25% of the potential is being utilized, the range of estimates is 0.1 to 20 million tons. Mahua, Pongamia pinnata, Jatropha, Neem, Pilu, Sal, Kusum, Jojoba, Undi, and Bhikal are among the almost 150 non-edible tree-borne oilseeds found in India. These species contain anything from 21% to 73% oil. Due to their hardiness, ease of handling, and great development in a variety of agro-climatic settings, Jatropha Curcas and Pongamia pinnata were chosen as the most suitable tree-borne oil seeds for biodiesel production. For making biodiesel, the oils from these plants are perfect. The transesterification of mahua oil was demonstrated in an experiment by Ghadge and Raheman, to be a three-step process [10]. According to Ma and Hanna, the production cost of biodiesel is roughly 1.5 times more than that of regular diesel, which is the largest drawback of using biodiesel [11]. This cost may constitute as much as 75% of manufacturing expenditure. To make biodiesel, most of the oils are edible. The battle for gasoline and food is fierce. Producing biodiesel from non-edible feedstock also yields respectable results. The oil's free fatty acid content determines how biodiesel is converted. According to Strezov and Evans, if it's more than 2.5%, the two- or three-step procedure is applied [12].

An article based on the concept of waste to energy by MNRE (2021), (Ministry of Renewable Energy) states that being a developing nation, India is undergoing industrialization and urbanization at a rapid pace. The developments taking place all around the country have led to increased quantities of waste, which are causing detrimental effects on the environment. Lahiri reported that proper treatment of waste in any form, whether solid, liquid, or gaseous, is important before permanent disposal [13]. Waste management is ensured to be significant if there is proper segregation of waste at the source itself and then the waste goes through different paths of recycling to safeguard the ecological balance. One of the forms of liquid waste that is disposed of without any treatment more often is the used vegetable oil, which originates from vegetable oil made from biological sources such as palm, soybean, olive, and sunflower, as discussed [14]. A report by Economic Times, 2019 suggests that India uses 2,700,000,000 gallons of vegetable oil, out of which 140 crore liters of used vegetable oils can be successfully collected to produce a useful form of energy, namely biodiesel. The present scenario is such that India has 850,000,000 gallons of gasoline requirement per month on average. The government targets biodiesel blending of diesel by 5 percent by the end of 2030. The biodiesel requirement is enormous, which also ensures successful waste-to-energy conversion.

The renewable and non-polluting properties of biodiesel make it a great substitute for diesel fuel. In addition to reducing production costs, recycling leftover vegetable oil as feedstock for biodiesel manufacturing helps maintain a clean and healthy environment. For this reason, there has been speculation that biodiesel, a mixture of leftover vegetable oils and non-edible oils, may be economically accessible if its manufacturing could be optimized. Realizing the hypothesis calls for an in-depth familiarity with the entire procedure. Upcoming chapters will elucidate this. To lower biodiesel production prices and determine the optimal feedstock for large-scale production, optimization techniques may be used for the transesterification process without the introduction of heat.

1.2. Research Motivation

Extensive efforts have been made in the field of biodiesel production to form blends with diesel; still, the cost of biodiesel remains a major drawback in this field. When raw sources like non-edible oil extract of plants are considered, the production of the plant becomes an important factor. Jatropha, being an important feedstock for biodiesel production, is widely grown. But it also requires barren land for production. With the yearly production of the plant, the quality of the soil will also decrease with time if proper care is not taken. All these factors require time as well as finance. Now, if used vegetable oil is considered, then this whole problem of plantation and procurement of feedstock can get sorted. The Times of India (2009) reported that Indian Railways is reportedly consuming biodiesel in large amounts. The Clean Cities Alternative Fuel Price Report, 2023, gives the national average fuel price of biodiesel as 4.95$ per gallon, which stands at 1.30$ per liter, and that of diesel is 4.25$ per gallon, which stands at 1.12$ per liter in the USA. Another report of Indonesia known as Biofuels Annual, 2022 states that the price of biodiesel is 1.04$ per liter and the price of diesel is 0.67$ per liter in Indonesia. The calorific value of biodiesel is 12% less than that of diesel, as reported by Olivera and Da Silva [15]. Therefore, it is said that the calorific value of 1 kg of diesel is equivalent to the calorific value of 1.120 kg of biodiesel.

The process of transesterification requires heat energy to move the reaction in the forward direction for a stipulated time of two hours. The transesterification can be done under ambient temperature conditions with the best-fit data. This will considerably decrease the cost of production. The structural analysis of alky esters of different types of used vegetable oils is required to compare the difference in the compositions in with-heat and without-heat conditions. The use of biodiesel in diesel engines changes the properties of the exhaust gas, and the change due to the use of biodiesel produced by used vegetable oils from different sources must be studied.

1.3. Aims and Objectives

Biodiesel, made from recycled vegetable oil, is the focus of this study. The variety of oil does not stay consistent because it is sourced from various places. Each transesterification uses a single type of oil exclusively, without mixing, because the yield is dependent on the oil type. The goal of this research is to develop a simple, cost-effective, and scalable technique for producing biodiesel from various feedstock oils and used vegetable oils. A key step in doing this is optimizing the process parameters. Studying the interaction influence of operational parameters on the production of biodiesel may be done using either a statistical technique or the optimization by trial-and-error procedure. The yield and reaction parameters will vary with the kind of oil. The association between biodiesel's physicochemical qualities and its structural analysis can only be derived through structural analysis. By using gas chromatography, the components of fatty acid alkyl ester may be identified. Reducing the cost of producing biodiesel can be achieved through another intriguing method. Temperatures high enough to facilitate transesterification are naturally present in tropical regions. By delving into the "with heat" and "without heat" scenarios, this may be explored further. Additional research on biodiesel's characteristics can help establish how well they match the requirement. Biodiesel blends made from various feedstocks can be used to test the efficiency of compression ignition (CI) engines.

The following are the study's aims and objectives.

- Biodiesel production from different types of used vegetable oils and raw vegetable oils (non-edible).
- To optimize the yield of biodiesel by changing the operating parameters within the given range
- Optimization of process parameters of biodiesel production from used vegetable oils by response surface methodology.
- To study the performance of a diesel engine fueled with biodiesel blends produced from different used vegetable oils blended with diesel.
- Evaluation considering the yield and properties of biodiesel from used vegetable oil of different plant-based feedstock.
- Feasibility in the manufacturing of biodiesel from different used vegetable oils under ambient temperature conditions.
- Comparative study of the differences in the components of the fatty acid alkyl ester from each kind of source in with-heat and without-heat conditions by performing gas chromatography of each sample.

There are essentially four parts to this study. The first is the biodiesel output from several fritter businesses. Following this, each reaction's oil type is preserved independently, without mingling. To do this, we must address the origins of our oil purchases. In the second stage, optimization is performed using the oil that produced the highest yield in the previous stage. The optimal yield was achieved by utilizing the statistical technique. In phase three, biodiesel is synthesized using heat and ambient temperature settings from various types of used vegetable oils. Under varied working circumstances, the fatty acid methyl ester components of the same oil type will be examined. Under both with and without without-heat circumstances, we will examine how the biodiesel's various physicochemical characteristics vary. The next step is to test the compression ignition engine's performance using biodiesel made from various recycled vegetable oils.

2. Literature review

2.1. Review of Earlier Work

According to the Statistical Review of World Energy, 2021, India's oil consumption in 2016 was 212.7 million tons, putting it third in the world behind China and the United States. To keep up with demand, the country has had to import a lot of oil as its reserves aren't enough. Consequently, the economy is facing certain challenges. The quest for alternative energy sources within the nation was initiated after Al-Widyan and Al-Shyoukh verified that toxic gas emissions are harming both human health and the environment [16]. According to Leung and Guo, there are several sources for biodiesel production; nevertheless, a significant barrier to its commercialization is the high cost of feedstock, which in turn renders biodiesel a very expensive product [17]. Now, it's clear that used vegetable oil is a great, inexpensive source of biodiesel. In 2016, the country's vegetable oils industry authority said that soybean oil imports to India reached over 4 million tons, a fourfold rise from the previous five years. A study conducted by Banerjee et al. in 2014 sheds information on the amount of leftover vegetable oil that fritter businesses in Kolkata dispose of. According to Chincholkar et al., vegetable oils have several potential applications such as clean, biodegradable, and nontoxic alternative fuels. Reduced emissions of carbon dioxide, sulfur, smoke, and particulate matter are the results of using essential fatty acids, and derivatives as fuels for diesel engines [18].

2.1.1. Low-Cost Feedstock

According to a 2011 assessment by Ejaz and Younis, over 300 potential feedstocks for biodiesel production have been discovered. Biodiesel are made using both conventional and non-conventional feedstocks, which are listed in Table 2.1. Wild oils, vegetable oils, animal fats, edible oils, and oils that are not edible are all part of this category. While rapeseed is used in Europe, soybean oil is used in the US. Malaysia makes use of palm oil, and India uses jatropha oil. Authors Singh S.P. and Singh D. suggested that the source of biodiesel largely depends upon the climate of a region. The climate decides the nature of the crop to be grown, which indirectly infers the nature of the feedstock for biodiesel in that area. Biodiesel needs to fulfill two criteria, which are low-cost and large-scale production [1].

Ejaz and Younis said that edible vegetable oils are more expensive than diesel fuel; thus, as a result, non-edible crude vegetable oils and waste vegetable oils are seen as better options for producing biodiesel at a lower cost [19].

Table: 2.1. Conventional and Non-Conventional Feedstock [19]

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Saydut examined sesame (Sesamum indicum L.) seed as a potential substitute feedstock for making biodiesel. The sesame (Sesamum indicum L.) seed oil methyl ester was produced by Transesterifying the crude sesame oil. The fuel qualities of sesame seed oil are enhanced by transesterification. This research lends credence to the idea that sesame seed oil may be refined into biodiesel, a sustainable alternative to diesel [20].

According to research conducted by Sinha et al. in 2008, India ranks second globally in rice production, only behind China [21]. Bran, a byproduct of milling rice that includes anywhere from fifteen to twenty-three percent oil, is a low-value byproduct. Currently, the sector is converting over 3.5 million metric tons of rice bran into approximately 0.65 million metric tons of oil. Little is done with this oil that isn't fit for human consumption. An enormous amount of rice bran, an agricultural byproduct, is generated (around 8% w/w of paddy). It might be a great low-cost alternative feedstock for making biodiesel. Results of biodiesel generation from waste sunflower oil with varied methanol to oil molar ratios were published by Tomasevic and Siler-Marinkovic in [22].

Research by Alptekin et al. also suggests the use of corn oil, chicken fats, and fleshing oils like animal fats as feedstock for biodiesel production [23]. A report by Canakci and Sanli infers that the main hindrance to the commercial use of biodiesel is the high cost of feedstock. Used frying oils, and yellow and brown grease have enough potential but are less expensive [24].

2.1.2. Chemical Structure of Oils

Triglycerides, diglyceride, and a trace amount of monoglyceride make up the bulk of animal fats and oils derived from plants, according to a 2011 review by Ejaz and Younis [19]. C12H23 is a typical chemical formula for diesel fuel. Large molecules are a result of the vegetable oils' lengthy chains with numerous branches. Vegetable oils have a molecular weight of 850 to 995, far greater than diesel's average molecular weight of 168.

Morrison and Boyd provided the molecular structure of a triglyceride molecule, which is seen in Figure 2.1. Triglycerides consist mostly of three fatty acid sets and a single glycerol stem [25]. Fatty acids significantly impact the chemical characteristics of lipids and oils because, as stated by Canakci and Sanli (2008), they make up 94% to 95% of triglycerides.

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Fig. 2.1 A triglyceride [25].

Singh and Singh report that there is enough oxygen inside the molecular framework of the triglyceride [1]. If the three fatty acids are identical, then it can be called a simple triglyceride, but different fatty acids give mixed triglyceride. The fully saturated ones have hydrogen with no double bonds, but those having one or two double bonds are monounsaturated and polyunsaturated fatty acids, respectively. The increase in the carbon deposits in the engine is due to the fully saturated fatty acids. Distinct from one another are the fatty acids for their degree of unsaturation, length of their chain, or reaction due to the presence of other chemical groups.

Table: 2.2 The chemical structure of common fatty acids in different types of feedstocks [26].

Illustrations are not included in the reading sample

Morrison and Boyd explain that in chemical terms, fats are carboxylic esters derived from glycerol and are known as triacylglycerol or triglycerides, as shown in Fig 2.1. Each kind of oil has different proportions of carboxylic acids, which define the characteristic properties of the fat or oil and depend upon the source of the oil [25]. The physicochemical characteristics of biodiesel are highly dependent on the fatty acid distribution in the triglyceride that is utilized as feedstock, according to research conducted by Canakci and Sanli in 2008 [24]. Table 2.2 lists the most prevalent fatty acids present in various feedstocks.

2.1.3. Procedure Adopted for Biodiesel Production

Plant oil is not ideal for direct use as a fuel due to the presence of water, phospholipids, free fatty acids, and other contaminants [26]. Compression ignition engines may run on refined oil that has undergone a little chemical transformation. According to research by Singh and Singh et al., there has been a lot of work put into creating vegetable oil derivatives that mimic the characteristics and performance of diesel fuels generated from hydrocarbons [1]. Problems with using non-edible oils as diesel fuel are largely linked to their high viscosity, low volatility, and polyunsaturated characteristics, according to the research. Four processes—pyrolysis, microemulsion, dilution, and transesterification—are available for their modification. In terms of efficiency and affordability, transesterification has emerged as the best option among these.

2.1.4. Transesterification

According to Canakci and Sanli, transesterification is a chemical reaction that transforms triglycerides into ester and glycerol [24]. Triglyceride bifurcation and the introduction of the alkyl radical from the alcohol of choice substitute the glycerol stem, setting in motion the reaction. Because it is a reversible reaction, a catalyst is needed to enhance the characteristics of the fuel that is produced and to speed up the process. As a result, the feedstock's high viscosity is reduced to a level comparable to diesel by transesterification. Figure 2.2 below illustrates the reaction's mechanism. The triglyceride consists of three acid chains, denoted as R1, R2, and R3. "R'" indicates that the alkyl alcohol was utilized. As a by-product, glycerol is produced when three moles of alcohol react with one mole of triglyceride, yielding three moles of fatty acid alkyl monoesters.

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Fig: 2.2. Transesterification Reaction [24].

Fonseca et al. reported that the used vegetable oil contains many unwanted elements that are formed during cooking such as free fatty acid in larger concentrations, water, and polar and non-volatile compounds [27]. These factors adversely affect the yield of FAME and decrease the efficiency of engines. The presence of water, whether in feedstock or alcohol, can lead to saponification, which consequently makes water washing difficult and decreases the yield of biodiesel [21].

2.1.5. Process Parameters for Biodiesel Production via Transesterification

The operating parameters are responsible for the yield of biodiesel obtained after transesterification. As discussed by Murugesan et al., the type of catalyst is also a factor depending upon the type of feedstock and, hence, can be treated as an operating parameter [26].

- Selection of Catalyst
- How moisture and free fatty acid levels are impacted
- Raw oils used
- The proportion of ethanol to veg oil
- Amount of catalyst
- Reaction temperature
- Mixing intensity in revolutions per minute (rpm)
- Reaction time

2.1.5.1. Selection of Catalyst

Acid catalysis is more convenient than alkali catalysis for transesterification; however, both methods are viable. According to research by Freedman and Pryde, alkali catalysis is more efficient than acid catalysis [28]. When it comes to feedstocks, there are a lot of different opinions on which catalyst is best. The free fatty acid (FFA) level must be less than one for the base catalyst to be effective [29]. Crabbe et al. added that base catalysts may be utilized with FFAs greater than one, although a higher catalyst quantity is required [30]. Contrarily, base catalysts work marvels when oil's FFA is less than two. Additionally, they found that using a base catalyst instead of an acid catalyst speeds up the transesterification reaction by a factor of thousands.

Nevertheless, feedstock with FFA levels up to 5 can be efficiently treated using base catalysts. Research conducted in 2015 sheds light on the widespread industrial use of powerful basic catalysts. The primary arguments in favor of using an alkaline catalyst rather than an acidic one are the former's shorter reaction time, higher conversion rate, and reduced catalyst required. Figure 2.3 shows the process of alkali-based transesterification, which was described by Singh and Singh [1]. The graphic illustrates the three-step reaction process. Here, B stands for the catalyst, and R for the alcohol's alkyl group. In the initial stage, the anion of alcohol (the methoxide ion) attacks the carbonyl carbon atom of the triglyceride molecule. This forms a tetrahedral intermediate, which then combines with another alcohol (methanol) to renew the anion of alcohol. Finally, a diglyceride and fatty acid ester are formed by rearranging the tetrahedral intermediate. The same procedure is then repeated for monoglyceride and diglyceride in that order, yielding three moles of glycerol and alkyl ester, and finally, for the end. Because they are quicker and require less catalyst, alkali-based transesterification is often chosen [24]. In addition, the internal engine components are protected against corrosion when an alkaline catalyst is used.

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Fig: 2.3. The process of transesterifying vegetable oils using an alkaline base [1].

When the feedstock contains water and has a high acid value, acid catalysts work well, as described by Sinha et al. (2008) [21]. Soap formation and separation get problematic when using base catalysts because of how sensitive they are to water concentrations. Base catalysts do not work well with most non-edible oils because their acid values are too high. Therefore, acid catalysts are employed in these instances. Figure 2.4 shows the acid-catalyzed transesterification process for monoglyceride from vegetable oil. It begins with protonation of the ester's carbonyl group, which leads to carbocation. A tetrahedral intermediate is then produced following a nucleophilic assault on the alcohol. To rejuvenate the catalyst and create a new ester, these intermediate removes glycerol. The image below illustrates the mechanism of acid catalyzes, where the catalyst's H+ ion is engaged in the process.

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Fig: 2.4. Mechanism of acid-catalyzed transesterification [21].

An acid catalyst can be employed when the concentration of free fatty acids and water in triglycerides is high. However, these catalysts come with several drawbacks, including a slower reaction rate, higher reaction temperatures and pressures, and a greater alcohol demand. According to Peng et al., there are several problems with using acid catalysts, including reactor corrosion and environmental concerns [31].

2.1.5.2. Effect of Free Fatty Acid and Moisture Content

Freedman et al. found that the amount of moisture and free fatty acids in the oil had a significant impact on the biodiesel output [28]. The alkyl ester interacts with water to produce free fatty acid if the feed supply contains moisture. In essence, hydrolysis happens, releasing free fatty acids, which is completely impractical for making biodiesel. R stands for the biodiesel triglyceride group and R1 for the alkyl group in the process seen in Fig. 2.5.

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Fig: 2.5. Hydrolysis of alkyl ester [28].

Murugesan et al. confirmed that free fatty acid and moisture content are critical factors for assessing the feasibility of transesterification in vegetable oil [26]. An FFA value of less than 3% is required to bring the base-catalyzed reaction to a successful conclusion. The effectiveness of the conversion decreases as the acidity of the oil increases. Soap formation can be caused by either an excess of catalyst or an inadequate quantity of catalyst. For base-catalyzed alcoholysis to work, the materials utilized must adhere to guidelines. The acidity level of the triglycerides needs to be reduced. Soap makes the reaction more viscous or forms a gel, which hinders the reaction and the separation of glycerol; however, adding additional sodium hydroxide catalyst makes up for greater acidity.

2.1.5.3. Raw Oils Used

According to Young-Soo Chung et al., the choice of feedstock accounts for 75% of the overall cost of producing biodiesel [32]. Biodiesel fuel qualities are often impacted by the selection of raw materials, according to Murugesan et al. (2009) [26]. This is because various kinds of vegetable oils and animal fats may contain different kinds of fatty acids. Clutane number, oxidation state, and cloud point are all impacted by the saturated fatty acid alkaline chain length and degree. It is possible to make and choose biodiesel to have a certain feature since its final physical qualities are dependent on the properties of the free fatty acids present. The output of the final product from each raw material is likewise affected by this. According to research by Martinez et al., feedstock availability dictates raw material selection. Ratanjyot, Karanja, and jatropha have all been deemed highly promising by the Planning Commission of India [33]. These crops are very adaptable, meaning they can be produced in almost any climate with the right amount of rain. It is possible to make premium biodiesel from the oil that is extracted from these oilseeds. Biodiesel are made from these seeds, which are not edible.

2.1.5.4. Ratio of Alcohol and Oil

According to Sinha et al., the molar ratio is a crucial variable in biodiesel manufacturing [21]. The stoichiometry in the equation allows for a proportional variation of the molar ratio, as seen in 3:1. They found that when the quantity of alcohol needed to propel the reaction ahead grows with an increase in molar ratio, the yield of rice bran oil is greatly enhanced. The ratio of methanol to oil was adjusted from 6:1 to 15:1, with a 9:1 ratio producing the highest output. A higher molar ratio results in a slower rate of yield growth. There is little correlation between the molar ratio and ester viscosity. Most of the ester yield is dictated by the catalyst quantity. According to research conducted by Ahmed in 2015, the most effective molar ratio for extracting jatropha oil from methanol was 6:1 [22]. Glycerine becomes more soluble in solution at larger molar ratios, such as 12:1, which reverses the process and reduces yield. Although a molar ratio of 3:1 is required for the transesterification reaction, according to Keera, the addition of extra alcohol speeds up the process [35]. Up to a point, greater molar ratios do increase yields. The molar ratio has been adjusted from 3:1 to 12:1, with all other parameters held the same, with methanol used as alcohol.

Before 6:1, the reaction is not complete. The optimized yield is obtained at 6:1 for cottonseed and soybean oil. Increasing the ratio to 12:1 lowers the ester yield as the excess alcohol interferes with glycerine formation and drives the reaction backward. Refaat et al. produced biodiesel for three sets of molar ratios from waste vegetable oil, giving an optimum yield of 96.5% at 6:1 [36]. A molar concentration of 6:1 has given the optimum yield of cottonseed methyl ester to Rashid et al. (2009) [37]. According to their findings, less than 6:1 has led to the incompletion of the reaction, whereas a molar ratio greater than 6:1 leads to a dilution effect. However, a note must be taken that the optimum yield depends simultaneously on other parameters as well.

2.1.5.5. Amount of Catalyst

When it comes to transesterification reactions, most studies have relied on NaOH catalysts and thought they worked best with used vegetable oil [38]. Because of their superior conversion efficiency, reduced reaction temperature requirements, and ability to complete reactions more quickly, base catalysts are chosen over acid catalysts. Since the method is quicker and the reaction conditions are mild, an alkali catalyst is most utilized [39]. Triglyceride transesterification can be facilitated using acid, enzyme, or heterogeneous catalysts, among others. The acid catalysts H2SO4, H3PO4, and HCl work well with oils that are rich in free acid and have high water content. A catalyst that is alkaline is preferable since the reaction takes place four thousand times quicker than one that is acidic.

Industrial equipment is less likely to be corroded by alkali catalysts. Murugesan et al. observed that vegetable oils could be converted into ester with a conversion rate of 94 to 99% when the concentration was between 0.5 and 1.0% (w/w) [26]. A range of concentrations of KOH, from.5% KOH w/w of oil to 1.5% KOH w/w was employed as a catalyst in the study by Ishnah Ul Mishal Tooba1et al. [40]. The graph displays the % yield of biodiesel, which might vary. Dharma et al. confirmed that biodiesel produced from a mixture of Jatropha and Ceiba pentandra had a yield that varied with catalyst proportion, ranging from 0.5% to 2% w/w of oil [41]. While the amount of catalysts is one component, other factors also contribute to changes in yield in this case.

2.1.5.6. Reaction Temperature

The reaction is carried out at atmospheric pressure for a specified duration, near the boiling point of the corresponding alcohol (60-700°C). According to the study by Murugesan et al., the optimal conditions for producing esters are temperatures between 60 and 800°C and a molar ratio of 6:1 [26]. Molecules move and collide more often as the reaction temperature rises, according to the experiment detailed in Moulita and Kalsum [42]. The heat generated by the collision of these particles contributes to the overall acceleration of the biodiesel conversion rate. The result is an increase in the percentage yield. However, because alcohol has a low boiling point, it evaporates at much higher temperatures. Because of this, the biodiesel percentage yield drops.

2.1.5.7. Mixing Intensity

While discussing all the operating parameters of biodiesel, Murugesan et al., also discussed mixing intensity [26]. Due to the immiscibility of oils and fats, mixing is crucial in NaOH– MeOH or any other catalyst alcohol solution. Once mixed and the reaction is started, stirring is not required. For eg, the yield of methyl esters at 360 rpm and 600 rpm are the same after 3 hours of reaction. It is possible to reverse the transesterification reaction, therefore faster revolution per minute decreases the total time of the reaction process. Using vegetable oil as feedstock, the production of biodiesel was highest at 2 hours, 1% catalyst, and 600 rpm, giving 96% yield.

2.1.5.8. Reaction Time

Farah Dhia Abdul Karim et al. reported that the reaction time depends on other processing parameters [43]. A lesser reaction time will not lead to a homogenous mixing of the reactants. Acid transesterification takes a very long time in comparison to alkali transesterification. P. Bhandare et al., explain that completion of transesterification is dependent on time. Experiments were conducted in three sets in which time varied as 40 minutes, 80 minutes, and 120 minutes [44]. The longest duration of reaction time exhibited the largest percentage yield. However excess reaction time leads to a backward reaction, causing hydrolysis of esters.

2.1.6. Transesterification for Changes in Process Parameters

Transesterification is the most straightforward and inexpensive method for producing biodiesel; Sinha et al. studied this process and found that it could be used for rice bran oil [21]. To get the best-fit data based on % yield and viscosity, the following parameters were optimized: methanol: oil ratio, catalyst concentration, stirring speed, temperature, and agitation rate. When comparing the effectiveness of NaOH and KOH, Encinar et al. (2007) discovered that KOH performed better. Additionally, they found that KOH was preferable to NaOH as a catalyst for biodiesel and glycerol separation since it was easier to work with. Acid transesterification has been utilized to produce biodiesel from waste palm oil. According to Al-Widyan and Al-Shyoukh, when the concentration of free fatty acids is high, acid transesterification or two-step transesterification is employed [16]. According to Mangus et al., biodiesel may also be made from clean sunflower oil and used vegetable oil scraps. Using a methanol/oil molar ratio of 6:1 and a reaction temperature of 650°C, they were able to produce more than 96% biodiesel in about 1 hour [45].

2.1.7. Optimization of Process Parameters of Biodiesel Production

(CCD) made it possible to optimize the yield. In their 2023 study, Van Nhanh Nguyen et al. detailed the implementation of the Box-Behnken design (BBD) using Design Expert 9.0.2.0. To evaluate the impact of temperature, catalyst concentration, and sludge solids concentration, one study ran 17 separate tests in sets of 3, and the program took the average [46]. Siti Fatimah Abdul Halim et al based on CCRD to optimize the transesterification of used palm oil using lipase catalyst in a packed bed reactor [47]. There is still a long way to go before we can optimize process parameters to extract the highest possible production of biodiesels from RSM-treated non-edible oil mixtures. The impacts of the main operational factors on biodiesel yield using waste oil from cooking were examined in another research by Hamze et al. (2015) using a response surface approach based on Box-Behnken Design (BBD) [48]. An ethyl ester with a high concentration of oleic acid was synthesized and improved using response surface methods in a 2007 study by Bouaid et al. from sunflower oil. The most important factor influencing conversion was the concentration of KOH in the catalyst. To improve the biodiesel output from non-edible feedstock, Dharma et al., suggest that optimization efforts should be prioritized [41].

2.1.8. Qualitative Analysis of Biodiesel

According to Knothe, the fatty acids do not change during biodiesel conversion [49]. Chromatography, according to Still et al., is the method by which the unknown components of a mixture may be identified by the separation of their components [50]. Even when separated, the qualities of the individual elements are preserved. According to research conducted by Chowdhury et al., biodiesel, which is also called fatty acid methyl ester (FAME) and is made using methanol as a catalyst, is composed of methyl esters of saturated, monounsaturated, and polyunsaturated fatty acids [51]. Rabu et al., compared the component retention durations with those of a typical mix to establish the composition of biodiesel made from used vegetable oil [52]. Below is the chromatogram showing the proportion of each fatty acid type in this biodiesel made from vegetable oil using a palmitic acid base.

Table 2.3 Fatty acid profile of the biodiesel from used vegetable oil [52].

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The amount of methyl ester in the product decreases because methanolysis stays incomplete due to the presence of glyceride in the ester when the acid value of the feedstock is higher, requiring a bigger catalyst for neutralization. Gas chromatography was useful in identifying the presence of saturated and unsaturated fatty acid methyl esters in palm biodiesel. The levels of oleic acid methyl ester and linoleic acid methyl ester are higher in Jatropha biodiesel.

2.1.8.1. Evaluation of Properties of the Biodiesel from Its Composition

The assessment of oxidative stability, which is dependent on the overall degree of unsaturation of the FAME, is confirmed by Sarin et al., 2010 [53]. What follows is a definition of the correlation:

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OS stands for biodiesel's total oxidation stability, and X represents the weight percentage of total unsaturated FAME.

According to research conducted by Dunn, R. O., the engine characteristics of biodiesel are determined by its fatty acid alkyl esters [54]. All of biodiesel's characteristics are based on the fatty esters' chemical structures. Biodiesel's total cold-flow characteristics and viscosity may be determined by identifying the structure of fatty acid alkyl esters.

Saturated fats are unable to absorb any more hydrogen since they only contain one carbon-carbon bond. An unsaturated fat, on the other hand, has at least one double bond and may undergo hydrogenation. The cetane number (CN) is affected by factors such as the unsaturation degree, the amount of CH2 groups in the ester moiety, the location of the double bonds, and the length of the chain [55]. A fuel's cetane number is an indicator of its ignition quality; it's also a measure of the ignition time delay or the amount of time that passes between fuel injection and engine ignition. As the length of the chain grows in unsaturated esters, the concentration of CN rises. As the amount of double bonds increases, the CN of unsaturated FAMEs decreases. As Knothe explains, CN levels rise as the hydrocarbon chain nears its terminal double bond [56]. As the molecular weight of an ester increases for a given set of alcohols, CN increases as well, demonstrating that CN is alcohol-dependent. According to Gopinath et al., a higher percentage of linoleic acid and linolenic acid may indicate reduced CN because of the high degree of unsaturation [57].

Table 2.4 Fatty acid profile of sunflower oil FAME composition (%) [57]. Abbildung in dieser Leseprobe nicht enthalten

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Palmitic acid is more abundant in sunflower fatty acid methyl ester (SUFAME), as may be shown here. According to Gopinath et al., large levels of unsaturation may indicate reduced CN in the presence of a higher percentage of linoleic acid and linolenic acid [57]. One study by Choudhury et al. (2015) used mathematical modeling to demonstrate a relationship between viscosity and FAME components [58]. The viscosity of FAME is increased by the saturated and monosaturated portions and decreased by the polysaturated portion; hence, the viscosity of FAME is reduced as the number of double bonds rises. For all esters, the viscosity rises with longer chains and falls with more unsaturation, according to a 2015 study by Gopinath et al [59]. The viscosity of saturated methyl ester is proportional to the number of carbon atoms present. According to research by Maria Jorge Pratas, et al., the density of FAMEs goes down as the length of the alkyl chain goes up and up as the saturation level goes up [60]. According to Alptekin and Canakci, the engine performance and emission characteristics are significantly impacted by fuel density, as density is correlated with NOx emissions and cetane number [61]. Gopinath et al. provided information indicating biodiesels with higher density have lower cetane numbers [59].

The quantity of heat released when one kilogram of fuel is burned completely is known as the heat of combustion. Because the energy of a fatty acid alkyl ester is directly proportionate to its chain length, the composition of the biodiesel's alkyl esters has a greater impact on the heat of combustion [62]. The energy content of fatty acid alkyl esters rises as the alcohol concentration increases for a given chain length [63]. The heat of combustion is reduced when the un-saturation level rises because fewer hydrogen molecules are present. The heat of combustion rises as the carbon atom count rises.

Knothe defines the iodine value as the parameter to measure the degree of unsaturation of the FAME [64]. Iodine value increases with alcohol moiety and increases with an increase in alcohol size. As reported by Kalayasiri et al. (1996) the equation gives the iodine value of biodiesel.

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Here, IV stands for iodine value, i for each kind of fatty acid alkyl ester, D for the number of double bonds in each kind of ester, Ai for the percentage of each kind in the biodiesel, and MWi for the molecular weight of each kind.

According to Gopinath et al., alkyl esters' melting points rise with more alcohol moieties and fall with more unsaturation. The degree of saturation is the primary determinant in determining the cloud point (CP) and pour point (PP). This is because, in comparison to unsaturated molecules, saturated ones have a greater melting point [59]. Gopinath et al. outlined the formula for calculating the cloud point and pour point, which is illustrated below [59].

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Cloud point (CP), pour point (PP), and percentage of palmitic fatty acid methyl ester (PFAME) are the relevant variables in this context regarding biodiesel. The molecular weight of the biodiesel's fatty acids is the saponification value. The number of milligrams of potassium hydroxide (mg KOH) needed to saponify one gram of oil sample is the unit of measurement. The saponification value, as published by Gopinath et al., may be found using the formula below [59].

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What we have here is the saponification value (in milligrams of potassium hydroxide per gram of oil, abbreviated as SV), the percentage of each ingredient by weight (Af), and the molecular weight (MWf) of each oil component. Because of their more complicated structure and larger molecular weight, vegetable oils have substantially higher kinematic viscosity and density than diesel. When compared to mineral diesel, biodiesel has similar characteristics. Therefore, compression ignition engines may run on it, either straight or in a mixture. The fuel doesn't need any significant engine modifications, according to Ejaz and Younis [19]. Cvengros and Cvengrosova found that waste oils of all kinds may be transformed in the same way as fresh oils or fats of the same category, provided that their acidity and water content are kept within limits [66]. Biodiesel may be made from raw soybean oil using an alkaline-catalyzed transesterification process, according to studies published in 2009 by Qi et al [67]. Compared to diesel, it has a lower calorific value but higher viscosity, density, and flash point.

There is a considerable reduction in the emission of gases such as smoke, carbon monoxide, hydrocarbons, and nitrogen dioxide, according to the emission characteristics. According to Pradhan et al., research on engine performance using biodiesel-mixed diesel fuel has been extensively planned due to concerns about pollution and environmental damage [68]. Furthermore, biodiesel significantly lowers NOx emissions. Mangus et al. (2014) found that when biofuel is utilized as a diesel or blended alternative, the combustion ignition (CI) engine's performance and emissions are affected by the biofuel's molecular structure. Although fuel consumption drops as the oil's oxygen content rises, NOx emissions rise as the oil's unsaturation level rises. Vegetable oil is largely imported by India. In turn, this results in a daily deluge of used frying oil (UFO). Diesel engine performance in Brazilian circumstances with different blend amounts has been studied using UFO. Paulo et al. found that the B20 biodiesel mix resulted in the greatest fuel use, while the B5 blend resulted in the lowest [69].

The effects of crude rice bran biodiesel, diesel, and mixes thereof on diesel engine performance are the subject of a 2017 study by Chabra et al [70]. While B10 and B20 blends performed similarly to diesel, B40 performed poorly in comparison to the other blends and diesel itself. Because plant oil contains nitrogen naturally, it participates in the formation of nitrogen oxides, which is why fuels blended with biodiesel have more NOx than diesel. As previously shown, the brake-specific fuel consumption (BSFC) rises when the biodiesel ratio in the fuel mix increases [71]. To keep the food market unaffected, this approach focuses on using just the type of oil that is discarded and is no longer edible. To determine which oil is suitable for mass manufacturing, the performance of several blends is examined after manufacturing. Each type of methyl ester has also had its characteristics tested.

3. Methodology

3.1. Materials Used for Biodiesel Production

Merck Ltd.'s 99% pure methanol was utilized. The low price of methanol makes it a better choice than ethanol. Sodium hydroxide of 97% purity was used by Merck Ltd. Phenolphthalein 1% indicator solution was from Merck. Sodium hydroxide of 97% purity was used by Merck Ltd. A plastic jar of Merck Emplura Potassium Hydroxide pellets was used in later experiments as it gives a greater yield when compared to sodium hydroxide. Distilled water for washing. Glassware like beakers, separating funnels, conical flasks, glass rods, viscometer, and condenser of Borosil were used. Buschner conical flask manufactured by Borosil. Two plastic tubes were used for the circulation of water through the condenser. A submersible pump was used for the circulation of water during transesterification. A Remi 5-litre Hot Plate Magnetic Stirrer was used. An aquarium pump, a Vacuum filtration pump, and a Mercury thermometer up to 1000°C were used for temperature measurement. The clamp stands for Beam Balance. Several steps are involved in biodiesel production for each kind of sample. The parameters change depending on the requirements, but the steps followed throughout the production process are the same. The flow chart is in Fig. 3.1 and can give an idea about the steps involved and the sequence followed.

3.2. Steps to be followed for Biodiesel Production

The following steps have been followed to produce biodiesel from used vegetable oil and raw oils in the chemical laboratory of the Department of School of Energy Studies.

3.2.1. Pre-processing of the Feedstock

The feedstock includes non-edible oils which are directly collected from seeds of different plants like mahua, karanja, and sesame. These oils do not require pre-processing. However, the used vegetable oil collected from different kinds of sources contains all kinds of unwanted solid and fine particles that need to be separated from oil before undergoing transesterification. Primary filtration is done in the container itself in which it is contained. The heavy, large particles are allowed to settle for 2-3 days, after which the upper larger layer of the oil, which is free of large heavy solid particles, is passed through cottonwood. This makes the oil free from large or small light particles of food. Now, the oil only contains fine carbon particles.

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Fig. 3.1. Steps of biodiesel production [Present work].

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Fig. 3.2. Cotton wool [Present work].

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Fig. 3.3. Gravity Filtration through cotton wool [Present work].

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Fig. 3.4. Vacuum Filtration Pump [Present work].

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Fig. 3.5. Filtered oil obtained by vacuum filtration [Present work].

This can be done through the vacuum filtration technique. In a Buchner conical flask, the neck is fitted with a ceramic Buchner funnel topped with filter paper. The suction, by a pump of 1 Horsepower. The oil, after filtration, gets stored in the bottom of the flask, whereas the black carbon particles are separated into the filter paper. Each filter paper can filter almost 0.5 to 1 liter of oil, depending on the level of impurities. Fig. 3.2, Fig. 3.3, Fig. 3.4, and Fig. 3.5 describe the process of filtration.

3.2.2. Estimation of the FFA content

A non-aqueous colorimetric titration using potassium hydroxide, isopropanol as the titrant, and p-naphtholbenzenein as the indicator is described in ASTM D974, 2014. How much potassium hydroxide is required to neutralize a 1-gram oil sample is the acid number. The estimated fatty acid content of the biodiesel or feedstock is provided by this acid number. Fatty acid is produced when the ester bonds in triglyceride feedstock undergo hydrolysis. The following is the formula for calculating the acid number or acid value (AV), as described by Mahajan et al., [72]. In milligrams per gram, the acid value is given.

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Multiplying the acid value by a factor that is equal to one-tenth of the molecular weight of the fatty acid in question divided by the molecular weight of potassium hydroxide yields the percentage of free fatty acid content. The conversion factor is a common name for this. The factor has a value of.503. Due to the high concentration of oleic acid in the sample, the molecular weight of the fatty acid in question is 282.4. The proportion of fatty acids (FFAs) is given as a percentage. Hence, the following is the relationship between acid value and free fatty acid:

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3.2.3. Free Fatty Acid Estimation of the Oil

The following steps have been followed for fatty acid estimation, keeping in mind the details mentioned in ASTM D974, 2014.

Note: Normality is equal to molarity in the case of KOH as well as NaOH, as their equivalent weights are equal to their molecular weights. The blanking process was neglected as the KOH and isopropyl alcohol used were from a sealed package.

Step 1: A 0.1 N solution of KOH was prepared by mixing 0.561 g of KOH with 100 ml of water. This solution was used for the titration of the oil. This solution can be kept in store for almost 2-3 months. In the case of NaOH, the solution of the same strength is prepared by mixing 40 gm of NaOH in 100 ml of water.

Step 2: 2 gm of oil was collected in an Erlenmeyer flask and mixed with 10 ml of Isopropyl Alcohol (2-propanol) which is the titration solvent.

Step 3: 7-8 drops of Phenolphthalein were added to the mixture.

Step 4: The solution was titrated against .1 KOH/NaOH solutions.

Step 5: Continuous shaking and addition of the titration solution continue till there is a visible color change in the oil-alcohol solution, which persists for at least 15 seconds.

Step 6: The amount of titrating solution for color change is recorded. This value is used in the equation mentioned above to calculate the acid value.

Step 7: The free fatty acid content is calculated with the help of the acid value obtained.

3.2.4. Calculation of the Amount of Catalyst

Percentage of catalyst weight /weight of oil = x%. This means that 100 gm of oil requires x gm of catalyst for the reaction process. Now, depending on the amount of oil considered, the amount of catalyst required for transesterification will be calculated. In the case of two-step transesterification, the percentage of catalyst volume/volume of oil.

3.2.5. Calculation of the Amount of Alcohol

The molar ratio of alcohol/acid and oil = y: 1

[Note: Acid must be considered in case of esterification.]

This means that y moles of alcohol/acid react with 1 mole of oil

Mass of oil considered = z gm (In all cases mass of 100 ml of the corresponding oil has been considered.)

The molecular weight of oil = Mass of 1 mole of oil = MWo

As discussed by Pubchem, 2023 the molecular weight of methanol is 32.042 gm/mol. Therefore, the molecular weight of methanol is considered as 32 gm throughout this study.

The molecular weight of alcohol/acid = MWa

Mass of y mole of alcohol/acid = y* MWa

Mass of alcohol/acid to react with z gm of oil = Illustrations are not included in the reading sample

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The volume of alcohol can be calculated with the help of the density of alcohol. Here, z gm has been considered as the mass of 100 ml of oil. The density of methanol has been considered as 791.8 kg/m[3] as discussed in Stack Exchange, 2015.

Similarly, if the volume of oil is mentioned, then the corresponding mass can be calculated with the help of a beam balance.

Here, the molecular weight of the waste oils is the same as that of the corresponding fresh oil. Although heating causes oxidation, the fatty acid components remain more or less the same as obtained by gas chromatography in the later stages.

3.2.6. Acid Esterification

Which sort of transesterification procedure may be used depends on the free fatty acid concentration. Oils with a free fatty acid concentration higher than 2.5% were subjected to acid transesterification in this investigation. The proportion of free fatty acids is higher in mahua oil and other non-edible oils. Thus, in this example, alkali transesterification followed acid esterification. Sodium hydroxide is an acid that is utilized in the transesterification process. Sulfuric acid initiates esterification, which is then followed by transesterification aided by an alkaline solution.

In addition to reducing the biodiesel output, oils with high free fatty acid content react with KOH to generate soap, which further complicates separation in the separating column. These oils can't be saponified until they're esterified with acids like H2SO4. The esterified oil and water-alcohol combination are the results of the reaction between the oil and H2SO4. The use of a separating funnel allows for the separation of this combination. Transesterification can be performed after separation. Due to its high FFA concentration (17.5%), Mahua (Madhuca indica pinnata) oil was esterified in our study using H2SO4. A 500 ml Erlenmeyer conical flask is used, and the oil and necessary amounts of methanol are added to it while being swirled constantly using a magnetic stirrer. The next step is to set a constant value for both the temperature and the stirring rate. As you mix, slowly add the acid to the flask using a dropper. The next step is to secure the flask's lid with a reflux condenser so that no methanol may escape. A cooling effect is created when water enters the reflux condenser and then exits from the top. Vaporized methanol is condensed and then returned to the system. After the allotted time has elapsed, the system is stopped, and the crude solution is transferred to a separator funnel. After the allotted time has passed in the separating funnel, the mixture will have separated into two distinct layers. On top, you can see the methanol and water combination, and at the bottom, you can see the esterified oil, which is now ready to be transesterified. The titration technique verifies that the esterified oil contains fatty acids. Once the fatty acid concentration drops below 2.5%, further transesterification might begin.

3.2.7. Mixing and Neutralization

The catalyst reacts with the methanol to form methoxide, which then reacts with the base oils. It is best to start by mixing the methanol in a mixer before adding the catalyst, as most catalysts (e.g., NaOH, KOH) are solid and do not dissolve easily in methanol. Once the catalyst is fully dissolved in the methanol, it is ready to be added to the oil. The neutralization process starts immediately upon adding methoxide to oil. The oil will be pretreated by reacting particular alkaline catalysts with free fatty acids or basic acids. This means that more catalysts are needed to finish the reaction. Figures from Canacki & Sanli and others suggest that catalysts can combine with oil's free fatty acids to produce soap and water [73].

Here, the catalyst is sodium hydroxide.

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Fig: 3.6. Soap formation reaction [73]

3.2.8. Transesterification

In a reaction vessel, add the oil, alcohol, and catalyst and stir to initiate the transesterification process. A magnetically stirred reactor is the usual reaction vessel for the continuous alkali-catalyzed biodiesel production process. The oil, catalyst, and alcohol are mixed at a temperature just below the boiling point of the alcohol (64.5°C for methanol) to expedite the process. To keep alcohol loss to a minimum and to ensure full conversion of the oil to its esters, the reaction pressure is typically kept close to atmospheric pressure. Saponification and the subsequent separation of the glycerol by-product may be hindered if the levels of free fatty acids or water are very high.

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Fig: 3.7. Transesterification set up and stirring [Present work].

Fig: 3.8. Colour of the mixture with heating beginning of the reaction [Present work].

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Fig: 3.9. The color of the mixture at the end of the reaction [Present work].

3.2.9. Separation

The transesterification process is finished by letting the reaction mixture stand for 12 to 18 hours. The separating funnel is used to pour the solution. Rubber bands are used to secure the knob of the separating funnel, which is sealed with petroleum jelly, a fatty substance. More and more of the separation becomes apparent as the reaction mixture cools. As seen in Figure 3.10, two distinct strata are discernible.

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Fig: 3.10. Separation of biodiesel and glycerine [Present work].

The upper stratum comprises light yellow, and at the base it is brown. The upper layer is biodiesel or methyl ester, and the lower layer is glycerol. Glycerol, being denser, settles at the bottom, and the biodiesel floats on the top. Both layers contain some impurities like excess catalysts and excess alcohol. After the allowed settling time, opening the knob first lets out the glycerol and then the biodiesel is let out. Volumes of both biodiesel and glycerol are measured in measuring cylinders. Now the biodiesel is ready for washing to remove any excess catalyst present in it.

3.2.10. Purification of Crude Biodiesel by Water Washing

After the glycerol phase is separated during the transesterification procedure, the remaining catalyst, water, unreacted alcohol, free glycerol, and soaps all contribute to the crude biodiesel's pollution. Bubble cleaning uses distilled water. To wash biodiesel using bubble washing, a layer of water is placed underneath the fuel and then inflated with air bubbles. The water is drawn up into the biodiesel in a thin layer encircling the air bubble and then flows back down through the biodiesel when the bubble bursts at the top of the tank. How forceful the washing procedure is dependent on the air volume and bubble size. Huge bubbles with powerful airflow are sufficiently aggressive, whereas smaller bubbles with weaker fluxes are not. It is recommended that the volume of water be twice that of biodiesel. Fig. 3.11 shows the steps required for this, which include using an air stone and an aquarium pump. A hose made of plastic links the airstone to the power source. The pump is responsible for creating the air bubbles. A more effective method of washing is this.

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Fig: 3.11. Bubble Washing [Present work].

The high solubility of glycerol and alcohol in water makes water washing a great tool for removing these contaminants together with any lingering salts or soaps. To clean water, all you need is either distilled warm water or water that has been softened. Distilled warm water slows the formation of emulsions and keeps saturated fatty acid esters from precipitating because of its mild washing effect. Using softened water removes any traces of magnesium and calcium and neutralizes any alkali catalysts that may still be present. To get the oil and residual water to separate after each wash, let the mixture sit in the separating funnel for a while. The next step is to use pH paper to measure the water's pH. The water is washed until its pH matches the color of the pH paper, which is 7. This ensures that the water is free of any dissolved acids or bases. As a result, washing continues until the water phase turns clear, signifying the full removal of pollutants. After that, a separation funnel is used to separate the biodiesel and water components. After washing the moisture present in the biodiesel must be removed as the presence of moisture decreases the flash point and fuel's calorific value. It also increases the viscosity of the fuel. Heating is done in two steps.

Firstly, three beakers are cleaned and dried. Biodiesel with moisture is kept in the first beaker. Biodiesel with moisture is an opaque yellow liquid. A small amount of this biodiesel is poured into the second beaker and heated on an electric heater. When the biodiesel becomes slightly more transparent, it is poured into the third beaker. This continues till the first beaker is empty. The second step includes heating the biodiesel kept in the third beaker. The third beaker is kept in an air oven with the temperature set at 80°C for 20 minutes. Due to this heating, if any excess methanol is still present, it also escapes. Biodiesels are now free of all impurities. Now, the final biodiesel is obtained, as shown below in Fig. 3.12. The volume of biodiesel obtained is measured after the oil attains ambient temperature.

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Fig: 3.12. Refined biodiesel [Present work].

3.3. Apparatus Used for Measurement of Different Properties of Biodiesel

3.3.1. Estimation of Density

The density was measured with the help of a pycnometer shown on Fig. 3.13. The volume of the biodiesel (V) inside the specific gravity bottle or pycnometer was measured first. The mass of the specific gravity bottle was measured both as empty (MA) and filled with biodiesel (MB) in the beam balance. The difference between the masses was calculated and divided by the volume (V).

Density of biodiesel = Illustrations are not included in the reading sample

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Fig: 3.13. Pycnometer [Present work].

3.3.2. Flash Point and Fire Point

The apparatus depicted in Figure 3.14 for measuring flash points and fire points was utilized. A cup was filled with oil to a certain point, and it was the instrument's main feature. A motor swirled continually during the operation, and a thermometer with a maximum temperature of 300 °C was part of it. Within the biodiesel-filled cup was the thermometer's bulb. Within the cup, there was a hole that could be used to insert a fire source. The temperature began to climb as soon as the electricity was turned on. After the temperature reached 70°C with a 5-degree interval, the fire was automatically extinguished through the aperture, and the recording of that temperature began. This is the oil's flash point. The temperature at which the fire is ignited again after the flash point is also noted as the fire point. The biodiesel will be able to sustain a flame up to its fire point. The flash point of biodiesel is the temperature at which it begins to ignite and then goes out. This occurs many times before the firing point.

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Fig. 3.14. Pensky Martens Apparatus [Present work].

3.3.3. Estimation of Viscosity

In an internal combustion engine, the atomization of fuel is affected by its kinematic viscosity. The atomization of fuel is improved with a lower kinematic viscosity value. The internal combustion engine can burn fuel more efficiently as a result. One way to quantify the difficulty of moving a fluid is by looking at its viscosity. Ostwald’s viscometer is used for this purpose. As can be seen in Figure 3.15, Ostwald's Viscometer consists of a U-shaped glass tube that is suspended vertically in a bath that is heated to a predetermined temperature. It takes 15 milliliters of liquid to fill a measuring cylinder. We do this to make sure mistakes don't happen. The capillary, a vertical section of an extremely small bore, is situated in one U-shaped arm. On top of it, there's a bulb, and on the other arm, there's another bulb at the bottom part. The liquid is drawn into the top bulb by suction and then flows into the lower bulb via capillary action. Two marks, one above and one below the top bulb indicate a known capacity. Kinematic viscosity is proportional to the amount of time it takes for the liquid level to go from one mark to the next. It is measured by how long it takes for the test liquid to go from one location to another through a capillary with a predetermined diameter. Multiplying the duration by the viscometer factor yields the kinematic viscosity. As a standard, water is used to test viscosity. After passing water through the capillary, the time it takes for the water to fall from the top mark to the bottom mark is measured three times. Before adding biodiesel to the equipment, make sure it is completely dry. The viscometer was dried in an air oven at a temperature of 90 degrees Celsius until it was totally dry. The viscometer's capillary is then used to feed biodiesel through. The time taken for biodiesel to drop from top to bottom is measured three times again. The reference liquid, water, has a kinematic viscosity of.658 mm[2]/sec at 40°C and.800 mm[2]/sec at 30°C.

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Where η1 and η2 are the viscosities of the liquid and water, respectively, ρ1 and ρ2 are the densities of the liquid and water, and η2 is the viscosity of the reference liquid, water, as reported by Labmonk, 2018. Here, t1 and t2 are the time intervals of the liquid and reference liquid water to reach from the upper mark to the lower mark of the upper bulb.

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Fig: 3.15. Viscosity measurement using Ostwald’s Viscometer [Present work].

3.3.4. Estimation of Calorific Value

In a paper presented by Oliveira and Silva, calorific value is defined as the value that denotes the amount of energy liberated in a closed chamber during the occurrence of combustion [15]. It indicated the available energy in the fuel. You may use a bomb calorimeter to calculate the calorific value. A higher calorific value ensures a higher yield.

The bomb calorimeter's heat of combustion is determined using the 2013 substitution approach, as previously mentioned by Parr Instrumentation Company. The heat produced by the sample is contrasted with the heat produced by burning an equivalent amount of benzoic acid or another calorific-value-known standardizing substance. The results are obtained by subjecting a sample to high oxygen pressure and burning it in a metal-pressure vessel or bomb. The calorimeter measures the change in temperature in the absorbing media as a result of soaking up energy from the combustion. The sample's heat of combustion may be calculated by multiplying the calorimeter's temperature rise by an energy equivalent or heat capacity that was previously determined by testing with a reference material.

In Fig. 3.16, we can see the four main parts of a bomb calorimeter: (1) a bomb or container for burning the combustible charges; (2) a bucket or container with a stirring mechanism to hold a specific amount of water and the bomb; (3) an insulating jacket to protect the bucket from temporary thermal shocks while it burns; and (4) a thermometer or other sensor to measure the temperature changes inside the bucket. The pieces are labeled in the figure up there. As of 2013, the heat of combustion for benzoic acid was reported as 6318 calories/gram by Parr Instrumentation Company.

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Fig: 3.16. Inner parts of a bomb calorimeter (Source: Parr Instrumentation Company, 2013).

3.3.4.1. Standardisation

Before evaluating a chemical with an unknown heat of combustion, it is necessary to establish the energy equivalent or heat capacity of the bomb calorimeter (Parr Instrumentation Company, 2013). This figure stands for the combined heat capacity of the calorimeter's constituent parts, which encompass the metal bomb, the container, and the water contained therein. The quantity of heat created by the reference sample may be determined by multiplying its heat of combustion by the weight of the sample that was burned. By dividing this sum by the total temperature increase throughout the test, we may determine the calorimeter's energy equivalent. Figures 3.17, 3.18, 3.19, and 3.20 illustrate the components and operational status of the calorimeter.

The energy equivalent of the calorimeter will be calculated as follows.

Mass of benzoic acid = 8gms

Standard heat of combustion of benzoic acid = 6318 Cal/gm at 27°C Temperature rise due to the burning of a given mass of benzoic acid = 2.32 °C

The calorimeter's energy equivalent (W) is then computed as follows.

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Fig: 3.17. Bomb or vessel in which Combustion takes place [Present work].

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Fig: 3.18. Calorimeter in the laboratory [Present work].

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Fig: 3.19. Oxygen Cylinder to maintain Pressure of 30kg/cm² [Present work].

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Fig: 3.20. Calorimeter during operation [Present work]

3.3.4.2. Fuel Test

The calorimeter can test fuel samples once the energy equivalent has been established. Burning samples with known weights cause a temperature increase, which is monitored and recorded. The observed temperature rise is then multiplied by the calorimeter's energy equivalent to calculate how much heat was produced from each sample. The sample's calorific value (heat of combustion) is then calculated on a unit-weight basis by dividing this value by the sample's weight. The calorific value of biodiesel will be calculated as follows. Here, the heating value of carbon is 32.8 MJ/kg, as discussed by Engineering Toolbox (2001)

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4. Results & discussion

4.1. Results-

4.1.1. Yield of Biodiesel

The percentage of yield has been calculated based on the volume of biodiesel and the volume of oil. Table: 4.4. Shows the yields of biodiesels at different molar ratios.

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Table 4.4 Percentage yield of biodiesel prepared from 100 ml used vegetable oil (mixed) at different reaction conditions. (Reaction temperature = 55°C, stirring rate = 1000 rpm, reaction time = 1.5 hours)

Table: 4.4. Percentage yield of biodiesel [Present work]

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The amount of alcohol required for a given amount of oil was calculated as expressed in Equation 3.3 of section 3.2.5 of Chapter 3. Here, the calculation for the volume of alcohol required for the molar ratio of 3:1 has been shown below, and the same follows for all the other molar ratios as well.

Therefore, as described in section 3.2.5 of Chapter 3,

Density of oil = 0.91 kg/m³

Mass of oil considered of used vegetable oil (mixed) = 91 gm

In all cases, the mass of 100 ml of the corresponding oil has been considered. Therefore, 91 gm is the mass of 100 ml of used vegetable oil (mixed).

The molecular weight of used vegetable oil (mixed) = Mass of 1 mole of used vegetable oil

(Mixed) = 882 gm

The molecular weight of methanol = 32

The oil-to-methanol molar ratio = 3:1

Mass of 3 moles of alcohol/acid = 3 x 32

Mass of alcohol used to react with 91 gm of used vegetable oil (mixed) = 32 x 3 x 91/ 882

The volume of alcohol used to react with 100 ml of used vegetable oil(mixed) =12 ml.

Similarly, the other molar ratios were computed and are mentioned in Table 4.5.

Table: 4.5. Volume of alcohol for the corresponding molar ratios of alcohol: oil [Present work]

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The catalyst concentration has been calculated as discussed in section 3.2.4 of Chapter 3. Here, the catalyst concentration is .7%w/w of oil, which means that 100 gm of oil requires .7 gm of sodium hydroxide for the reaction process. Here, the mass of 100 ml of oil is 91 gm.

Therefore,

The amount of sodium hydroxide required for 100ml of oil = 0.637 gm.

In the same manner, the amount of alcohol (methanol) and the amount of catalyst (KOH) have been calculated for the linseed oil, mahua oil, and used vegetable oil (soybean), which is required for the process of transesterification.

Table: 4.6. Percentage yield of biodiesel prepared from 100ml of linseed oil (raw) at different reaction conditions. (Reaction temperature of 60°C and stirring rate of 1000 rpm) [Present work]

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Table: 4.7 Percentage yield of biodiesel prepared from 100ml of mahua oil (raw) at different reaction conditions. (Reaction temperature of 60°C and stirring rate of 1000 rpm)

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Table: 4.8. Percentage yield of biodiesel prepared from 100 ml of used vegetable oil (soybean) at different reaction conditions. (Reaction temperature = 45°C, stirring rate = 1000 rpm) [Present work]

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The best results of 86% biodiesel were achieved using used vegetable oil (mixed) at a molar ratio of 15:1, a catalyst concentration of 0.7% w/w of oil, a reaction temperature of 55°C, a reaction period of 1.5 hours, and a speed of 1000 rpm, as shown in Table 4.4. The ideal conditions for producing 90% biodiesel from linseed oil are listed in Table 4.6. These include a molar ratio of 9:1, a catalyst concentration of 1% w/w oil, a reaction temperature of 60°C, a reaction period of 2 hours, and a stirring rate of 1000 rpm. From mahua oil, the biodiesel yields 92% when acid esterified for 1 hour at 60°C with an acid catalyst concentration of 1.24% v/v of oil and a molar ratio of 8:1. Then, after 1 hour of alkali transesterification, the biodiesel yields 92% when basic catalyst concentration is 0.7% w/w of oil and a molar ratio of 6:1. For used soybean oil, the best conditions for producing biodiesel are as follows: a molar ratio of 9:1, a catalyst concentration of 1% w/w of oil, a reaction temperature of 45 0C, a reaction period of 2 hours, and 1000 rpm (see to Table 4.8 for details). The optimized parameters chosen to maximize biodiesel output from various oil types are displayed in Table 4.9 below.

Table: 4.9. Process parameters giving optimum yield of biodiesel for the different types of feedstocks [Present work].

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Due to the wide variety of vegetable oils used in cooking, some have experimented with making biodiesel from recycled oils, such as rice bran oil and old biodiesel. Because information on the utilized oil yield was unavailable during the study's execution, the parameters for the relevant raw oils were considered in the research cited below. According to Sinha et al. (2008), the best conditions for making biodiesel from rice bran oil are an alcohol-to-oil molar ratio of 9:1, a catalyst concentration of 0.75% NaOH, a reaction period of 1 hour, and a temperature of 550°C. However, the reaction time is maintained at 2 hours because this job uses rice bran oil. Here, KOH, the same catalyst concentration as specified in the research on rice bran oil optimization, has been applied. The process parameters for carrying out the transesterification reaction of biodiesel production from sunflower oil were studied by Saydut et al. (2016). These included a reaction temperature of 600°C, a catalyst concentration of 0.7% w/w of oil, a molar ratio of 6:1, and a reaction time of 2 hours. This research uses the same process parameters as the previous one to produce biodiesel from sunflower oil. It's reported that sunflower oil had a molecular weight of 876.16, thus, we utilized it as our molecular weight for the used oil. Li et al. (2011) also found that rice bran oil had a molecular weight of 867.90. The mass of the catalyst must be determined according to the steps outlined in Eq 3.2.4 of Chapter 3, and the amounts of methanol and oil may be determined according to the molar ratios given in Eq. 3.2.5 of Chapter 3. We received the used rice bran oil from the Bakultala Canteen at Jadavpur University in Kolkata. The used sunflower oil was purchased at the Kaikhali, Kolkata, Hot Chips retail business. Because of their widespread usage and easy availability, these two oils were converted into biodiesel. Thus, with the right channels in place, it is easy to collect spent oils of these two kinds. In Table 4.10, you can see the operating parameters for both the sunflower and rice bran utilized vegetable oils.

Table: 4.10. Process parameters giving optimum yield of biodiesel for used vegetable oil (rice bran) and used vegetable oil (sunflower) at different reaction conditions [Present work]

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4.1.2. Estimation of Properties of Biodiesel Prepared from Used Vegetable Oils and Raw Oils

The tables below show the properties of used vegetable oil (mixed), used vegetable oil (soybean), linseed oil, and mahua oil, respectively. The densities and viscosities of the biodiesels from the oils of used vegetable oil, linseed oil, and mahua oil have been determined using the formula in Eq. 3.3.1 and Eq. 3.3.3 of Chapter 3, respectively. Flashpoint and fire point have been measured as discussed in section 3.3.2 of Chapter 3. The calorific value of the optimum yield of biodiesel from used vegetable oil (mixed) has been calculated as described in section 3.3.4 of Chapter 3. In the case of biodiesel from the used vegetable oil (mixed) sample, the physicochemical properties of the optimum yield at 12:1 molar ratio are discussed in Table 4.11. For all the other samples of biodiesel, the properties of all the sets for each sample of biodiesel have been discussed.

Table: 4.11. Properties of the biodiesel produced from used vegetable oil (mixed) at optimum conditions [Present work]

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Table: 4.12. Properties of biodiesel prepared from linseed oil (raw) at different reaction conditions [Present work]

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Table: 4.13. Properties of biodiesel prepared from mahua oil (raw) at different reaction conditions [Present work].

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Table: 4.14. Properties of biodiesel prepared from used vegetable oil(soybean) at different reaction conditions [Present work].

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4.2 Discussion

Reaction temperature, oil-to-alcohol molar ratio, catalyst quantity, and stirring rate (in rpm) are the most important factors in transesterification. It was observed that the percentage of biodiesel output rose when the molar ratio of oil to alcohol was changed from 1:3 to 1:15 in this specific technique of biodiesel synthesis from used vegetable oil (mixed). The biodiesel yield was found to be proportional to the alcohol content. A steady 55ºC was maintained as the reaction temperature. Because doing so would have led to the alcohol being lost, the temperature was not raised anymore. The catalyst concentration was maintained within a range of 0.5% to 1.0% by weight (catalyst/oil). The characteristics of the free fatty acids will dictate the physical features of the finished biodiesel. In turn, it dictates how much of the raw material is converted into a finished good. Increasing the amount of methanol resulted in the highest possible yield of 86%. The efficiency of fuel atomization is affected by density, which is particularly significant when oil is used in a CI engine. The biodiesel that was produced in this study had a density of 870 kg/m[3]. The flash point of a fuel is the temperature at which it will ignite when it encounters a spark or flame. According to Ma and Hanna (1997), biodiesel is more suited for transportation than petrodiesel because of its higher flash point. An analysis revealed a flash point of 179ºC. When burnt with oxygen in a sealed container of constant volume, the calorific value of a fuel is the number of heat units released per mass of the sample. At 7816 kcal/kg, biodiesel has a high calorific value. The resistance of fluids to flow can be measured by their viscosity. At 30ºC, the biodiesel's kinematic viscosity was found to be 5.9 centistokes.

In the case of biodiesels from other feedstock, the density and viscosity of all the samples have been studied to compare the properties of the other yields with the optimum yield for biodiesel of each type of oil. After calculating the value of the above-mentioned physicochemical properties of the biodiesels made from used vegetable oil (soybean), linseed oil, and mahua oil, tabulated in Tables 4.12, 4.13, and 4.14, correspondingly, the variation in the properties can be identified in the graphs Fig. 4.2, Fig. 4.3, and Fig. 4.4 each. This shows the change in percentage yield and the change in kinematic viscosity for change in the molar ratio of respective biodiesels.

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Fig: 4.1. Molar ratio (alcohol: oil) versus percentage yield and kinematic viscosity of biodiesel produced from linseed oil (raw ) [Present work].

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Fig: 4.2. Molar ratios (alcohol: oil) versus percentage yield and kinematic viscosity of biodiesel produced from mahua oil (raw) [Present work].

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Fig: 4.3. Molar ratio (alcohol: oil) versus percentage yield and kinematic viscosity of biodiesel produced from used vegetable oil (soybean) [Present work].

While both the 9:1 and 12:1 ratio produce biodiesel from linseed oil, the viscosity of the latter is significantly higher at 12:1. At a 9:1 molar ratio and a catalyst concentration of 1% w/w, it demonstrates the best yield at 1.5 hours and 2 hours. While the density is lower at 2 hours than at 1.5, the viscosity is greater at 2 hours. The ideal reaction time for biodiesel from linseed oil is 2 hours, as has been observed in previous samples; this contrasts with the 1.5-hour output, which has been deemed suboptimal. Mahua oil is transformed into biodiesel by a two-stage transesterification process. The kinematic viscosity is reduced when the molar ratio is increased in Step I up to 8:1, but it remains relatively unchanged when the molar ratio is increased in Step II. Thus, the optimal parameter has been determined to be the molar ratio of 8:1 and 6:1 in the two following phases that provide the highest yield (Fig. 4.3). Changing the molar ratio from 9:1 to 12:1 did not significantly enhance the kinematic viscosity of biodiesel made from used soybean oil. However, when the molar ratio increases, the yield marginally drops (Fig. 4.4). The molar ratio of 9:1 has so been considered. Viscosity is greater, which might be because of an incomplete reaction, even if maximum yield was achieved after 0.5 hours. Table 4.15 shows the most optimized yield and kinematic viscosity for all three biodiesels from different sources.

Table: 4.15. Optimized properties of biodiesel prepared from different types of feedstocks and their yields [Present work].

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Transesterification improves oil properties and brings them closer to diesel, according to the data. You may make good use of the methyl ester of used vegetable oil in place of diesel or combination with it. Biodiesel, made from recycled vegetable oil, has a vibrant yellow hue. Large food firms sell fried products, so it's not hard to discover and gather used vegetable oil. If they want to sell the spent oil to soap manufacturers, they must keep the food products' quality up. This oil has the potential to be used as a biodiesel feedstock. Because refined oil is used for cooking, there will be no competition for the food. Although the income is substantial, the amount of alcohol invested is rather large as well. To properly remove any excess alcohol after manufacture, the cost of production will increase. While NaOH has been employed as a catalyst up to this point, KOH is preferable for usage further on in the research due to its quicker reaction time. Increasing the yield is possible by collecting spent oil of a certain kind from a single source. After that, optimization may be carried out more efficiently. It is also vital to research raw, non-edible oils so that we may compare them to the oils that are utilized. Based on the comparison of the optimum yield features of various non-edible oils and utilized vegetable oils, the optimal source for biodiesel synthesis may be identified (Fig. 4.5).

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Fig: 4.4. Comparison of properties of biodiesel produced from used vegetable oil (mixed), linseed oil, mahua oil, and used vegetable oil (soybean oil) [Present work].

It can be very well observed that the density and viscosity are the lowest and yield is the highest in the case of biodiesel from used vegetable oil (soybean). Therefore, it can be concluded that, out of all the raw oils and mixed oils, the biodiesel from used oil (soybean) has given the optimum yield and has shown impressive results in terms of physicochemical properties. Since spent vegetable oil is not a food source and is typically discarded, it may be recycled to make biodiesel from stores that sell fritters. To get oil, the gathering of oil must be simplified. Obtaining the optimized yield is crucial for reducing manufacturing costs. Biodiesel made from recycled soybean oil have an optimal yield of 96% to 97%.

5. Conclusions

The current research examines the entire process, beginning with the collection of old vegetable oils and non-edible oils and ending with their final application as biodiesel. The research is organized into four sections. The process includes optimizing process parameters, conducting statistical analysis to achieve an optimized yield, testing the biodiesel in a diesel engine, and comparing the chemical composition of biodiesel made with and without heat from various used vegetable oils. Linseed oil has a yield of 90% and mahua oil of 92% when converted into biodiesel. However, biodiesel yields from recycled vegetable oils were as high as 86% and as low as 97%. The variation in biodiesel yields from recycled vegetable oils is attributed to variations in feedstock quality as well as catalyst and alcohol concentrations utilized in the reaction. From this, biodiesel made from recycled vegetable oils and other non-edible oils may achieve diesel-like qualities through the transesterification process. Changing the process parameters causes a shift in the yield %. Consequently, to see how the yield varies for each feedstock type for biodiesel synthesis, we have adjusted catalyst concentration, molar ratio, and reaction duration in different amounts while keeping a few parameters constant for each transesterification run.

The collection of used vegetable oil at times is a difficult process because the sources of feedstock are unknown at times and people prefer throwing the used oil rather than selling them at low prices. But bigger companies that produce fried food items have large amounts of used oil, which they sell to manufacturers of soap. Apart from this, Fast Moving Consumer Goods (FMCG) manufactures a large variety of products like chips, sweets, and many other items at cheaper rates. The products under FMCGs are present in every household and touch each part of the life of the consumer as reported by Wikipedia. 2023. If the initiative is taken by the companies of FMCG, then the collection of the used vegetable oil can become much easier. Therefore, oils that are not for consumption or are discarded after the use of their raw form can act as potential feedstock for biodiesel production. As can be observed that changes in process parameters change yield, it must be done to find a set of values for the process parameters that can give the optimized yield. Statistical analysis has helped in this study to provide sets of combinations of process variables. Biodiesel production for each set of parameters has given a set of predicted yields, which have been compared to the corresponding experimental yields. The various designs provided by the mathematical tool Response Surface Methodology (RSM) can be used to examine the process parameters at five and three levels. The interactive and the quadratic effects of the parameters can be studied by this method. From the graphs, the optimized parameters are obtained, and the transesterification is performed with the set of optimized parameters. There is a difference of 0.205% between the experimental yield and the predicted yield. This validates the process. Thus, the statistical analysis method minimizes the use of the trial-and-error method of selection of values of operating parameters for biodiesel production. Since the mixed oil has given lesser yield previously, the used vegetable oil of one soybean origin has been used in this part of the study. This oil has been used as it was readily available from a single source and could be easily collected for experimental purposes.

Only when internal combustion engines can operate on biodiesel mixed with diesel in varying quantities can its manufacturing be considered legitimate. Blends of biodiesel made from recycled vegetable oil (soybean, rice bran, and sunflower) have been utilized to power the engine (B5, B10, and B20). Tables showing the physical and chemical characteristics of USOME, URBME, and USUME biodiesels reveal that their densities are like diesel. Researchers have also shown that certain viscosities may be used as diesel mixes. Because the blends' viscosities are higher than diesel's, the brake-specific fuel consumption is lower for all of them. Blended biodiesels made from various sources have a little higher brake-specific fuel consumption (BSFC) than diesel at all loads. All biodiesels made from recycled vegetable oils have BSFCs that drop as the load rises. At any given load, the calorific content of blended biodiesel drops as the blending process continues. Given the versatility of biodiesel production, it is crucial to do qualitative research to determine the exact composition of biodiesel made from recycled oils. Used soybean, rice bran, and sunflower oils, both heated and unheated, have been transformed into biodiesels. There has been computation and verification of the many characteristics that rely on the unsaturation and saturation levels of the methyl esters. Research has shown that producing biodiesel without using heat by transesterifying the oil for two hours saves 2578.20 kcal of energy per liter of used vegetable oil. A heating system and stirring arrangement are currently included in transesterification systems. A heating setup is unnecessary if heat is not applied during manufacturing; the only equipment needed for stirring is the stirring unit. Blends of biodiesel and diesel fuel with different chemical compositions and fuel qualities may be easily utilized in diesel engines, according to studies. The capital cost of the transesterification reactor will be lower compared to current technology because heat is not used. In addition, the construction-related simplification means that not only will input costs fall but so will the capital expenditure required to set up the production system. Several components that were once necessary for heating, such as the thermostat control system, are now superfluous. A drop in yield, which results in a fall in the calorific value of the biodiesel produced, can be offset by a far bigger decrease in the heat input required to create the fuel. When weighed against the heat saved by doing away with the heater, the drop in calorific value from the reduced biodiesel output pales in contrast. Since operating and capital costs are reduced, the production cost is also reduced. The result is a manufacturing unit that is less complex than the standard model. Oil, alcohol, and catalysts are the reactants used in biodiesel manufacturing. Methanol, an alcohol with a boiling point of 64.9 °C and a propensity to generate explosive mixtures with air has been utilized in this investigation. This makes it very combustible, according to the 2023 edition of the Encyclopedia Britannica.

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Fig: 5.1 Proposed biodiesel productions from used vegetable oil at ambient temperature without application of heat [Present work].

Hence, any type of dangerous disaster may be avoided, and complex safety measures won't be needed if heat input is removed. Small-scale businesses can engage in production without implementing complex safety protocols. In Fig. 5.1, we can see a simplified design of the biodiesel manufacturing setup that does not include any heat input arrangements. Thus, from the above outcome of the study, it can be suggested that biodiesel can be readily produced from cheaper sources like used vegetable oils if the collection of the oil is channelized properly. It has also been concluded that heat is not mandatory to produce biodiesel as it can be produced without any application of heat under ambient temperature conditions. Further methanol, diesel, and biodiesel can be tried together to run the CI engine, and the study can be carried over further.

6. References

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7. List of figures

Fig: 1.1. Import of crude oil by India (barrel/day)

Fig. 2.1 A triglyceride

Fig: 2.2. Transesterification Reaction

Fig: 2.3. The process of transesterifying vegetable oils using an alkaline base

Fig: 2.4. Mechanism of acid-catalyzed transesterification

Fig: 2.5. Hydrolysis of alkyl ester

Fig. 3.1. Steps of biodiesel production

Fig. 3.2. Cotton wool

Fig. 3.3. Gravity Filtration through cotton wool

Fig. 3.4. Vacuum Filtration Pump

Fig. 3.5. Filtered oil obtained by vacuum filtration

Fig: 3.6. Soap formation reaction

Fig: 3.7. Transesterification set up and stirring

Fig: 3.8. Colour of the mixture with heating beginning of the reaction

Fig: 3.9. The color of the mixture at the end of the reaction

Fig: 3.10. Separation of biodiesel and glycerine

Fig: 3.11. Bubble Washing

Fig: 3.12. Refined biodiesel

Fig: 3.13. Pycnometer

Fig. 3.14. Pensky Martens Apparatus

Fig: 3.15. Viscosity measurement using Ostwald’s Viscometer

Fig: 3.16. Inner parts of a bomb calorimeter

Fig: 3.17. Bomb or vessel in which combustion takes place

Fig: 3.18. Calorimeter in the laboratory

Fig: 3.19. Oxygen Cylinder to maintain 30kg/cm[2]

Fig: 3.20. Calorimeter during operation Pressure

Fig: 4.1. Molar ratio (alcohol: oil) versus percentage yield and kinematic viscosity of biodiesel produced from linseed oil (raw)

Fig: 4.2. Molar ratios (alcohol: oil) versus percentage yield and kinematic viscosity of biodiesel produced from mahua oil (raw)

Fig: 4.3. Molar ratio (alcohol: oil) versus percentage yield and kinematic viscosity of biodiesel produced from used vegetable oil (soybean)

Fig: 4.4. Comparison of properties of biodiesel produced from used vegetable oil (mixed), linseed oil, mahua oil, and used vegetable oil (soybean oil)

Fig: 5.1 Proposed biodiesel productions from used vegetable oil at ambient temperature without application of heat

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Title: Biodiesel Production from Used Vegetable Oil and Raw Vegetable Oil. Research and Findings

Research Paper (postgraduate) , 2024 , 73 Pages , Grade: A

Autor:in: Zakir Hussain (Author), Ch. Sirishsa (Author), E. Adharsha (Author), D. Karthik (Author), Reshma Lakra (Author), Vani Gandham (Author), Thomas Lourdu Madanu (Author)

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Title: Biodiesel Production from Used Vegetable Oil and Raw Vegetable Oil. Research and Findings
Course: Chemical Technology
Grade: A
Authors: Zakir Hussain (Author), Ch. Sirishsa (Author), E. Adharsha (Author), D. Karthik (Author), Reshma Lakra (Author), Vani Gandham (Author), Thomas Lourdu Madanu (Author)
Publication Year: 2024
Pages: 73
Catalog Number: V1577093
ISBN (PDF): 9783389132302
ISBN (Book): 9783389132319
Language: English
Tags: biodiesel production used vegetable research findings
Product Safety: GRIN Publishing GmbH

Quote paper: Zakir Hussain (Author), Ch. Sirishsa (Author), E. Adharsha (Author), D. Karthik (Author), Reshma Lakra (Author), Vani Gandham (Author), Thomas Lourdu Madanu (Author), 2024, Biodiesel Production from Used Vegetable Oil and Raw Vegetable Oil. Research and Findings, Munich, GRIN Verlag, https://www.grin.com/document/1577093

Biodiesel Production from Used Vegetable Oil and Raw Vegetable Oil. Research and Findings

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Contents

Abstract

1. Introduction

1.1. General Introduction

1.2. Research Motivation

1.3. Aims and Objectives

2. Literature review

2.1. Review of Earlier Work

2.1.1. Low-Cost Feedstock

2.1.2. Chemical Structure of Oils

2.1.3. Procedure Adopted for Biodiesel Production

2.1.4. Transesterification

2.1.5. Process Parameters for Biodiesel Production via Transesterification

2.1.5.1. Selection of Catalyst

2.1.5.2. Effect of Free Fatty Acid and Moisture Content

2.1.5.3. Raw Oils Used

2.1.5.4. Ratio of Alcohol and Oil

2.1.5.5. Amount of Catalyst

2.1.5.6. Reaction Temperature

2.1.5.7. Mixing Intensity

2.1.5.8. Reaction Time

2.1.6. Transesterification for Changes in Process Parameters

2.1.7. Optimization of Process Parameters of Biodiesel Production

2.1.8. Qualitative Analysis of Biodiesel

2.1.8.1. Evaluation of Properties of the Biodiesel from Its Composition

3. Methodology

3.1. Materials Used for Biodiesel Production

3.2. Steps to be followed for Biodiesel Production

3.2.1. Pre-processing of the Feedstock

3.2.2. Estimation of the FFA content

3.2.3. Free Fatty Acid Estimation of the Oil

3.2.4. Calculation of the Amount of Catalyst

3.2.5. Calculation of the Amount of Alcohol

3.2.6. Acid Esterification

3.2.7. Mixing and Neutralization

3.2.8. Transesterification

3.2.9. Separation

3.2.10. Purification of Crude Biodiesel by Water Washing

3.3. Apparatus Used for Measurement of Different Properties of Biodiesel

3.3.1. Estimation of Density

3.3.2. Flash Point and Fire Point

3.3.3. Estimation of Viscosity

3.3.4. Estimation of Calorific Value

3.3.4.1. Standardisation

3.3.4.2. Fuel Test

4. Results & discussion

4.1. Results-

4.1.1. Yield of Biodiesel

4.1.2. Estimation of Properties of Biodiesel Prepared from Used Vegetable Oils and Raw Oils

4.2 Discussion

5. Conclusions

6. References

7. List of figures

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