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A Study on the Production of Biodiesel from Rubber Seed Oil (Hevea Brasiliensis) The demand for energy around the world is continuously increasing, specifically the demand for petroleum-based energy. Petroleum is the largest single source of energy which has been consuming by the world’s population, exceeding the other energy resources such as natural gas, coal, nuclear and renewable. 90% of energy consumption of the world is from petroleum fuels. The demand and the price of these fuels are increasing at an alarming rate. The world consumption for petroleum and other liquid fuel will grow from 83 million barrels/day in 2004 to 97 million barrels/day in 2015 and just over 118 million barrels/day in 2025 [1]. Under these growth assumptions, approximately half of the world’s total resources would be exhausted by 2025. Also, many studies estimating that the world oil production would peak sometime between 2007 and 2025. Therefore the future energy availability is a serious problem for us. A country like Bangladesh is heavily dependent on import of fossil fuel and coal. Such dependency makes economy of Bangladesh more vulnerable to external price shocks in the international energy market. Price of fuel in the international market has been showing rising trend since last few years. Bangladesh annually imports about 3.5 million tons of different fuel oils. Of them, some 1.3 million tons are crude oil, 1.45 million tons diesel, 380 tons kerosene, 215 tons jet fuel and 155,000 tons petrol and octane [2]. The search for alternatives of fossil fuels is a major environmental and political challenge also. Another major global concern is environmental concern or climate change such as global warming. Global warming is related with the greenhouse gases which are mostly emitted from the combustion of petroleum fuels. In order to control the emissions of greenhouse gases, Kyoto Protocol negotiated in Kyoto City, Japan in 1997 and came to effect since February, 2005. Now, Kyoto Protocol covers more than 160 countries globally and targeting to reduce the greenhouse gas emission by a collective average of 5% below 1990 level of respective countries. The Intergovernmental Panel on Climate Change (IPCC) concludes in the Climate Change 2007 that, because of global warming effect the global surface temperatures are likely to increase 1.1C to 6.4C between 1990 and 2100 [3]. Recent environmental and economic concerns have prompted resurgence in the use of biodiesel


throughout the world. In 1991, the European Community, proposed a 90% tax reduction for the use of biofuels, including biodiesel To solve both the energy concern and environmental concern, the renewable energies with lower environmental pollution impact should be necessary. Nowadays several new and renewable energies have been emphasized and biomass energy is one of the renewable energies among them. Biomass energy includes liquid biofuels and which are promising as alternative fuels with low environmental pollution impact, to replace petroleum based fuels. Some of the well known liquid biofuels are ethanol for gasoline engines and biodiesel for compression ignition engines or diesel engines. In recent years, systematic efforts were under taken by many researchers to determine the suitability of vegetable oil and its derivatives as fuel or additives to the diesel [4-6]. Biodiesel is a renewable and environmental friendly alternative diesel fuel for diesel engine. It can be produced from food grade vegetable oils or edible oils, nonfood grade vegetable oils or inedible oil, animal fats and waste or used vegetable oils, by the transesterification process. Transesterification is a chemical reaction in which vegetable oils and animal fats are reacted with alcohol in the presence of a catalyst. The products of reaction are fatty acid alkyl ester and glycerin, and where the fatty acid alkyl ester is known as biodiesel.

Fig:1.1 Biodiesel as a source of renewable energy. Biodiesel is an oxygenated fuel and which containing 10% to 15% oxygen by weight. Also it can be said a sulfur-free fuel. These facts lead biodiesel to more complete combustion and less most of the exhaust emissions from diesel engine. But, comparing the fuel properties of biodiesel and diesel fuel, it has higher viscosity, density, pour point, flash point and cetane


number than diesel fuel. Also the energy content or net calorific value of biodiesel is about 12% less than that of diesel fuel on a mass basis. Using biodiesel can help to reduce the world’s dependence on fossil fuels and which also has significant environmental benefits. The reasons for these environmental benefits are: using biodiesel instead of the conventional diesel fuel reduces exhaust emissions such as the overall life circle of carbon dioxide (CO2), particulate matter (PM), carbon monoxide (CO), sulfur oxides (SOx), volatile organic compounds (VOCs), and unburned hydrocarbons (HC) significantly. Methyl esters of vegetable oils or biodiesel have several advantages and optimum blend can be used in any diesel engine without modification. The use of vegetable oil based fuels is not a recent development. Rudolf diesel, the inventor of diesel engine, used peanut oil as a fuel for his diesel engine at the world exhibition at Paris in 1900. But the interest in vegetable oils decreases due to cheap and abundant supply of petroleum based fuels. But the shortage of petroleum based fuels their rising prices and harmful emissions have accelerated the research in biodiesel. The rubber tree (Hevea brasiliensis) is a perennial plantation crop, indigenous to South America and cultivated as an industrial crop since its introduction to Southeast Asia around 1876. Rubber plantations yield from 100 to 150 Kg/ha rubber seeds. Rubber seeds are composed of about 43% oil [7-8]. Rubber seed oil (RSO) is a semi-drying type oil [9-10] that does not contain any unusual fatty acids, but is a rich source of polyunsaturated fatty acids C18:2 and C18:3 that make up 52% of its total fatty acid composition [11]. RSO has already been shown to have many applications for industrial purposes, including possible uses for the manufacture of fatty acids, paint, alkyd resin, soap making, surface coatings, and waterreducible alkyds, as well as in the production of biodiesel and for use in fuel compression ignition engines. To date, no studies have been conducted on the properties of Bangladeshi rubber seed oil (BRSO), particularly those properties relevant to RSO’s industrial uses, such as the types of triacylglycerols (TAG) present, its thermal profile and its solid fat content. This paper is aimed to study the optimized condition of methanol, catalyst molar ratio of alkali catalysed transesterification reaction of crude rubber seed oil (CRSO) from Hevea brasiliensis sp. on the biodiesel quality and study the CRSO-biodiesel on the diesel machine


performances. The effects of reaction temperature and time on the conversion, yield of FAME and composition of the reaction product also investigated. In this study required physicochemical properties of crude oil, produced methyl esters, functional groups of TAG, thermal properties of BRSO were also evaluated. 2.1 Background Over 100 years ago Rudolf Diesel invented the cycle of diesel engine using the compressionignition method. The diesel engine was originally made to run on peanut oil, and only later did petroleum become the standard fuel. Rudolf Diesel said, "The use of vegetable oils for engine fuels may seem insignificant today, but such oils may become, in the course of time, as important as petroleum and the coal tar products of the present time."

Fig: 2.1 Portrait of Rudolf Diesel. With the advent of cheap petroleum, appropriate crude oil fractions were refined to serve as fuel and diesel fuels and diesel engines evolved together. In the 1930s and 1940s vegetable oils were used as diesel fuels from time to time, but usually only in emergency situations. Recently, because of increases in crude oil prices, limited resources of fossil oil and environmental concerns there has been a renewed focus on vegetable oils and animal fats to make biodiesel fuels. Continued and increasing use of petroleum will intensify local air pollution and magnify the global warming problems caused by CO2. Today, each country in the world is seriously involved in active search for substitutes for petroleum derivatives such as "biodiesel". There are many conceptual definitions of biodiesel. It can be defined as "Biodiesel is the mono alkyl esters of long chain fatty acids derived from


renewable feed stocks, such as vegetable oil or animal fats, for use in compression ignition (CI) engine�. Technically speaking, biodiesel is the alkyl ester of fatty acids, made by the transesterification of oils or fats, from plants or animals, with short chain alcohol such as methanol and ethanol. Glycerol is, consequently, a by-product from biodiesel production.

Fig: 2.2 Simplified representation of fatty oil to biodiesel conversion. 2.2 Biodiesel as alternative to fossil fuel Biodiesel is an alternative fuel similar to conventional or ‘fossil’ diesel. Biodiesel can be produced from straight vegetable oil, animal oil/fats, tallow and waste cooking oil. The process used to convert these oils to Biodiesel is called transesterification. This process is described in more detail below. The largest possible source of suitable oil comes from oil crops such as rapeseed, palm or soybean. In the UK rapeseed represents the greatest potential for biodiesel production. Most biodiesel produced at present is produced from waste vegetable oil sourced from restaurants, chip shops, industrial food producers such as Birdseye etc. Though oil straight from the agricultural industry represents the greatest potential source it is not being produced commercially simply because the raw oil is too expensive. After the cost of converting it to biodiesel has been added on it is simply too expensive to compete with fossil diesel. Waste vegetable oil can often be sourced for free or sourced already treated for a small price. (The waste oil must be treated before conversion to biodiesel to remove impurities). The result is Biodiesel produced from waste vegetable oil can compete with fossil diesel. [1]


2.3 Feedstock Biodiesel is derived from biological sources, such as vegetable oils or fats, and alcohol. Commonly used feedstock is shown in Table 2.1. Table 2.1: Feedstock used for biodiesel manufacture. Vegetable oils

Animal Fats

Other Sources

 Soybeans

 Lard

 Rapeseed

Tallow

Restaurant

Poultry fat

Cooking Oil

Canola oil (a modified version of rapeseed)

 Fish oil

 Safflower oil

 Recycled

(Yellow Grease)  Rice bran oil[25]

 Sunflower seeds  Yellow mustard seed  Rubber seed oil  Algae [28]

2.4 Methyl esters of fatty acids suitable as diesel fuel The analogy to hexadecane as “ideal” petro-diesel component shows why biodiesel is suitable as an “alternative” diesel fuel. The fatty acids whose methyl esters are now used as biodiesel also are long-chain compounds similar to long-chain alkanes such as hexadecane which make good petro-diesel. Petro-diesel consists of many components. Besides hydrocarbons, petro-diesel often contains significant amounts of compounds known as aromatics. Aromatics are cyclic compounds such as benzene or toluene. Aromatic compounds have low cetane numbers and therefore are undesirable components of petro-diesel. However, they have high densities and thus help elevate the energy contained in a gallon of the fuel. Polyaromatic hydrocarbons (PAHs) [29] are found in exhaust emissions of petro-diesel and, in reduced amounts, of biodiesel fuel. Biodiesel’s lack of aromatic compounds is often cited as an advantage.


Fats and oils are primarily water-insoluble, hydrophobic substances in the plant and animal kingdom that are made up of one mole of glycerol and three moles of fatty acids and are commonly referred to as triglycerides. Fatty acids vary in carbon chain length and in the number of unsaturated bonds (double bonds). The oil and fatty acids composition found in different vegetable oils and fats are summarized in following table. [4] Table: 2.2 Fatty acid composition of different oil (on % basis) [12] Fatty acid

Soybean

Cottonseed

Palm

Lard

Tallow

Coconut

Lauric (C12:0)

0.1

0.1

0.1

0.1

0.1

46.5

Myristic (C14:0)

0.1

0.7

1.0

1.4

2.8

19.2

Palmitic (C16:0)

10.2

20.1

42.8

23.6

23.3

9.8

Stearic (C18:0)

3.7

2.6

4.5

14.2

19.4

3.0

Oleic (C18:1)

22.8

19.2

40.5

44.2

42.4

6.9

Linoleic (C18:2)

53.7

55.2

10.1

10.7

2.9

2.2

Linolenic (C18:3)

8.6

0.6

0.2

0.4

0.9

0.0

2.5 Vegetable oils and biodiesel The major components of vegetable oils are triglycerides. The term triacylglycerols is being used more and more, but we will use the classical term in this discussion. Triglycerides are esters of glycerol with long-chain acids, commonly called fatty acids. Tables: 2.3, lists the most common fatty acids and their corresponding methyl esters. The trivial names of fatty acids and their esters are far more commonly used than their rational names. It is to be noted that fatty acids have higher melting points than their corresponding methyl esters. It is extremely important to realize that vegetable oils are mixtures of triglycerides from various fatty acids. The composition of vegetable oils varies with the plant source. Often the terms fatty acid profile or fatty acid composition are used to describe the specific nature of fatty acids occurring in fats and oils. Table: 2.3 Characteristics of Common Fatty Acids and Their Methyl Esters [14]


Fatty acid

Formula

Molecular weight

Melting point (ยบC)

Methyl ester Palmitic acid

C16H32O2

256.428

63-64

Methyl palmitate

C17H34O2

270.457

30.5

Stearic acid

C18H36O2

284.481

70

Methyl stearate

C19H38O2

298.511

39

Oleic acid

C18H34O2

282.465

16

Methyl oleate

C19H36O2

296.495

-20

Linoleic acid

C18H32O2

280.450

-5

Methyl linoleate

C19H34O2

294.479

-35

Linolenic acid

C18H30O2

278.434

-11

Methyl linolenate

C19H32O2

292.463

-52 / -57

2.6 Nonconventional vegetable oils as feedstock for biodiesel In most developed countries, biodiesel is produced from soybean, rapeseed, sunflower, groundnut, sesame, palm oil which are essentially edible oils and thus face high demand and more expensive than diesel fuel. A country like Bangladesh is not in a position to compromise its food producing landsd or edible vegetable oil to produce bio-diesel. In this perspective non-edible sources are the only option. Azam et al. [15] has studied on 75 species of indigenous oil seed bearing plants. Fatty acid compositions, IV and CN were used to predict the quality of fatty acid methyl esters of oil for use as biodiesel. Fatty acid methyl ester of oils of 26 species were found most suitable for use as biodiesel and they meet the major specification of biodiesel standards of USA, Germany and European Standard Organization. Some of these indigenous Bangladeshi non-edible oil seed plants are, Jatropha (Jatropha curcas), Karanja (Pongamia pinnata), Royna (Aphanamixis polystachya), Rubber (Hevea brasiliensis), Castor (Ricinus communis), etc. [15]. 2.6.1 Rubber seed oil as a non-conventional source:


Large area of land for rubber plantation is already allotted and we have over 92 000 acres of rubber plantation under BFIDC and non-governmental organization.[16] Rubber seed oil currently solely has the highest potential for biodiesel production. Bangladesh already existing rubber estates produce more than 2,000 tons of seeds/year, approximately 150 kg/acre [6]. Currently, it has no economic use, rather considered as a waste and can yield more than 500 tons (25%) of RSO annually. There are 16 governmental rubber estates in three different zones of Bangladesh, i.e. 7 are located in Chittagong Zone, 4 in Sylhet Zone and 5 in Madhupur Zone of Tangail District. The Table: 2.4 and 2.5 shows the rubber plantation in Bangladesh. Table:2.4. Rubber estates under BFIDC Lists of Rubber Estates under BFIDC. [16] Name and place 1.

Ramu Rubber Estate, Rumu, Cox's Bazar

Total area (acres) 2131.00

Year started

2.

Raojan Rubber Estate, Raojan, Chittagong

1378.00

1961

3.

Dabua Rubber Estate, Raojan, Chittagong

2120.00

1969

4.

Holudia Rubber Estate, Raojan, Chittagong

2246.00

1983

5.

Kanchannagor Rubber Estate, Ftikchachari,

2371.00

1983

6.

Tarakho Rubber Estate, Ftikchachari, Chittagong.

2436.00

1983

7.

Dantmara Rubber Estate, Ftikchachari,

3965.00

1970

8.

Rupichora Rubber Estate, Bahubol, Hobigonj

1832.00

1977

9.

Satgaon Rubber Estate, Srimongol, Moulovibazar

1744.00

1971

10.

Shajibazar Rubber Estate, Madhobpur, Hobigonj

2040.00

1980

11.

Bhatere Rubber Estate, Kulaura, Moulovibazar

2467.00

1966

12.

Pirgacha Rubber Estate, Madhupur , Tangail

2906.00

1987

13.

Chadpur Rubber Estate, Madhupur, Tangail

2379.00

1989

14.

Sontoshpur Rubber Estate, Madhupur, Tangail

1036.00

1989

1961


15.

Komolapur Rubber Estate, Madhupur, Tangail

994.00

1989

16.

Karnajhora Rubber Estate, Madhupur, Tangail

620.00

1994

Total

32635.00

Table: 2.5 Overall land distribution for rubber plantation in Bangladesh Name of the organization

Area of garden in acres

0

BFIDC

32 635

1 0

Rubber garden (Private, standing committee)

32 550

2 0

Development board of Chittagong Hill Tract

12 000

3 0

Duncun Brothers

7 500

4 0

James Finley

5 000

5 0

Messrs. Ragib Ali

2 500

6 0

Ispahani Neptune

800

7 Total 2.6.2 Exploitation of rubber plant:

92 985

2.6.2.1 Plant profile of rubber plant: Scientific classification Kingdom

: Plantae

Division

: Magnoliophyta

Class

: Magnoliopsida

Order

: Malpighiales

Family

: Euphorbiaceae


Subfamily

: Crotonoideae

Tribe

: Micrandreae

Subtribe

: Heveinae

Genus

: Hevea

Species

: H. brasiliensis

Binomial name

: Hevea brasiliensis.

Rubber plantations mainly consist of only one species, Hevea brasiliens, a variety of plants of the genus Hevea (Euphorbiaceae family), and native to Brazil. Commonly known as the rubber tree, Hevea brasiliensis is a tall erect tree with a straight trunk and bark which is usually fairly smooth and grey in colour. The plant, grows up to over 40 meters (m) in the wild. The rubber tree is a perennial (lasting for over 100 years) plant.The rubber tree flourishes in the tropics with annual rainfall of 2,000-4,000 mm evenly spread throughout the year, and temperatures ranging between 24-28°C. Rubber (hevea brasiliensis) tree starts to bear fruits at four years of age. Each fruit contain three or four seeds, which fall to the ground when the fruit ripens and splits. Each tree yields about 800 seeds (1.3 kg) twice a year. A rubber plantation is estimated to be able produce about 800-1200 kg rubber seed per ha per year [18], and these are normally regarded as waste. 2.6.3 Toxicity studies of Rubber seed oil: However, many studies of rubber seeds have indicated that the use of RSO for nutritional purposes faces various vital challenges, one of which is the presence of toxins in RSO. It is well known that some concentration of poisons will always be found in the seeds of all types of plants, including the seeds of the rubber plant. Rubber seeds known to contain linamarin[26,27]. A linamarin is a cyanogenic glucoside. The hydrolysis or cyanogenesis of linamarin by the endogenous enzyme linamarase (β-glucosidase) results in the formation of glucose and acetonecyanohydrin, which later decomposes into hydrogen cyanide (HCN) and acetone [27]. Linamarin has been demonstrated to protect the plant from herbivores, both animals and generalized insect feeders


The presence was confirmed in this study (18.6 mg/100 g). There have also been reports that fresh rubber seeds and its kernel contain about 63.8 to 74.9 mg of HCN per 100 g (George et al., 2000), as well as about 200 mg /100 g of seeds [26]. Heat treatment (roasting at 350°C for 15 minutes), soaking in hot water or in a 2.5% ash solution for 12 hours could work in detoxification (UNIDO, 1987), or storage at room temperature for a period of 2 to 4 months has been shown to be effective in reducing the hydrogen cyanide (HCN) content of rubber seeds [26]. 2.6.4 Potential of Rubber seed oil: Christopher Columbus is believed to have first found rubber in tropical South America around 1500. Hevea brasiliensis, the common variety of rubber tree produces 99% of world’s natural rubber. The seed contains an oily endosperm. Generally 37% by weight of the seed is shell and the rest is kernel. The oil content of air-dried kernel is 47%. The seed fall season in India is July September. Rubber seed oil is a non-edible vegetable oil. The increase in the price of non-edible oil in recent years generated interest in the collection and processing of rubber seeds. According to a study conducted by the rubber board, on an average, a healthy tree can give about 500 g of useful seeds during a normal year and this works out to an estimated availability of 150 kg of seeds per hectare. The price of rubber seeds is around one Indian rupee per kg. Rubber seeds are produced mostly in kerala (southern most state of India), the processing of rubber seeds is concentrated in Tamilnadu (another southern state). Table 2.6 Physicochemical properties of Rubber seed oil [17] Fuel Property Density (gm/cc3) Specific gravity Viscosity (cSt) Flash point (0C) Calorific

Diesel oil 830 0.830 3.55 55 43

Rubber seed oil 930 0.930 66 198 37.5

value(MJ/Kg)

Table 2.7 Fatty acid composition of rubber seed oil [17]

Biodiesel 860 0.860 6 72 35


Fatty acid composition (%)

Rubber seed

Palmitic (C16/0) Stearic(C18/0) Oleic(C18/1) Linoleic(C18/2) Linolenic(C18/3)

oil 10.2 8.7 24.6 39.6 13.2

2.7 Process overview of biodiesel production Different methods for using vegetable oil as alternative to diesel: 1. Direct use and Blending, which is the use of pure vegetable oils or the blending with diesel fuel in various ratio. 2. Micro emulsions with simple alcohols, 3. Thermal Cracking (Pyrolysis) to alkanes, alkenes, alkadienes etc 4. Transesterification (alcoholysis); 2.7.1 Direct use and blending The direct use of vegetable oils in diesel engines is problematic and has many inherent failings. It has only been researched extensively for the past couple of decades, but has been experimented with for almost a hundred years. Although some diesel engines can run pure vegetable oils engines, turbocharged direct injection engines such as trucks are prone to many problems. For short term use ratio 1:10 to 2:20 oil to diesel has been found to successful. [12] There have been many problems associated with using it directly in diesel engine.

[12]

This

includes: 1. High viscosity of vegetable oil interferes with the injection process and leads to poor fuel atomization. 2. The inefficient mixing of oil with air contributes to incomplete combustion, leading to high smoke emission. 3. The high flash point attributes to lower volatility characteristics. 4. Lube oil dilution. 5. High carbon deposits.


6. Ring sticking. 7. Scuffing of the engine liner. 8. Injection nozzle failure. 9. Types and grade of oil and local climatic conditions. 10. Higher cloud and pour points may cause problems during cold weather. These problems are associated with large triglycerides molecule and its higher molecular mass, which is avoided by chemically modified to vegetable oil in to biodiesel that is similar in characteristics of diesel fuel. 2.7.2 Micro emulsion Micro emulsion is defined as a colloidal equilibrium dispersion of optically isotropic fluid microstructures, with dimensions generally in the 1-15 nm range. They are formed spontaneously from two normally immiscible liquids and one or more ionic or non-ionic amphiphiles.[13]A microemulsion is designed to tackle the problem of the high viscosity of oils with solvents such as simple alcohols. The performance of ionic and non-ionic microemulsions where found to be similar to diesel fuel, over short term testing. They also achieved good spray characteristics, with explosive vaporization of the low boiling constituents in the micelles, which improved the combustion characteristics. In longer term testing no significant deterioration in performance was observed, however significant injector needle sticking, carbon deposits, incomplete combustion and increasing viscosity of lubricating oils were reported. 2.7.3 Thermal cracking Pyrolysis is the conversion of one substance into another by means of applying heat i.e. heating in the absence of air or oxygen with temperatures ranging from 450-850 0C. In some situations this is with the aid of a catalyst leading to the cleavage of chemical bonds to yield smaller molecules. The Pyrolysis of fats has been investigated for over a hundred years, especially in countries where there is a shortage of petroleum deposits. Typical catalysts that can be employed in Pyrolysis are SiO 2 and Al2O3. fractions were similar to fossil fuels. 2.7.4 Transesterification

[18]

The chemical compositions of diesel


Ramesh et al, 2002

[20]

stated that there are three stepwise reactions in transesterification

resulting in the production of 3 moles of methyl esters and one mole of glycerol from triglycerides. The overall reaction is as follows:

Fig: 2.5 Transesterification reaction The overall process is normally a sequence of three consecutive steps, which are reversible reactions. In the first step, from triglycerides diglyceride is obtained, from diglyceride monoglyceride is produced and in the last step, from monoglycerides glycerol is obtained. In all these reactions esters are produced. The stoichiometric relation between alcohol and the oil is 3:1. However, an excess of alcohol is usually more appropriate to improve the reaction towards the desired product: Triglyceride (TG) + ROH ↔ Diglycerides (DG) + RCOOR1 Diglycerides (DG) + ROH ↔ Monoglycerides (MG) + RCOOR2 Monoglycerides (MG) + ROH ↔ Glycerol (GL) + RCOOR3


There are several generally accepted ways to make biodiesel. Some are more common than others, e.g. blending and transesterification, and several others that are more recent developments e.g. reaction with supercritical methanol. An overview of these processes is as follows: Different methods for production of biodiesel by Transesterification (alcoholysis): (a) Homogenous acid/alkali catalyzed, (b) Heterogeneous acid/alkali catalyzed, (c) Microwave assisted transesterification, (d) Ultrasound assisted transesterification, (e) Bio/Enzyme catalyzed, (f) Catalyst free/ Supercritical and subcritical fluid 2.7.4.1 Acid catalyst esterification The transesterification process is catalyzed by Bronsted acids, preferably by sulfonic and sulfuric acids [28]. These catalysts give very high yields in alkyl esters, but the reactions are slow, requiring, typically, temperatures above 100 째C and more than 3 h to reach complete conversion. The mechanism of the acid-catalyzed transesterification of vegetable oils is shown in Scheme 5. Acid-catalyzed transesterification should be carried out in the absence of water, in order to avoid the competitive formation of carboxylic acids which reduce the yields of alkyl esters.


Figure: 2.6. Homogeneous acid-catalyzed reaction mechanism for the transesterification of triglycerides: (1) protonation of the carbonyl group by the acid catalyst; (2) nucleophilic attack of the alcohol, forming a tetrahedral intermediate; (3) proton migration and breakdown of the intermediate. The sequence is repeated twice. 2.7.4.2 Base catalyst transesterification The base-catalyzed transesterification of vegetable oils proceeds faster than the acidcatalyzed reaction [28]. Alkaline catalysts are less corrosives than acidic compounds, such as alkaline metal alkoxides and hydroxides as well as sodium or potassium carbonates. The mechanism of the base-catalyzed transesterification of vegetable oils is shown in Scheme 6. Alkaline metal hydroxides (KOH and NaOH) are cheaper than metal alkoxides, but less active. Even if a water-free alcohol/oil mixture is used, some water is pro- duced in the system by the reaction of the hydroxide with the alcohol. The presence of water gives rise to hydrolysis of some of the produced ester, with consequent soap formation. This undesirable saponification reaction reduces the ester yields and considerably difficults the recovery of the glycerol due to the formation of emulsions. Potassium carbonate, used in a concentration of 2 or 3 mol% gives high yields of fatty acid alkyl esters and reduces the soap formation [30]. This


can be explained by the formation of bicarbonate instead of water, which does not hydrolyse the esters.

Figure: 2.7. Homogeneous base-catalyzed reaction mechanism for the transesterification of TGs: (1) production of the active species, RO-; (2) nucleophilic attack of RO- to carbonyl group on TG, forming of a tetrahedral intermediate; (3) intermediate breakdown; (4) regeneration of the RO- active species. The sequence is repeated twice. 2.7.4.3 Supercritical Methanol The study of the transesterification of rapeseed oil with supercritical methanol was found to be very effective and gave a conversion of >95% within 4 min. A reaction temperature of 3500C, pressure of 30 MPa and a ratio of 42:1 of methanol to rapeseed oil for 240s were found to be the best reaction conditions. The rate was substantially high from 300 to 500 0C but at temperatures above 4000C it was found that thermal degradation takes place. Supercritical treatment of lipids with a suitable solvent such as methanol relies on the


relationship between temperature, pressure and the thermophysical properties such as dielectric constant, viscosity, specific weight and polarity .[15] 2.7.4.4 Biocatalysts Biocatalysts are usually lipases; however conditions need to be well controlled to maintain the activity of the catalyst. Hydrolytic enzymes are generally used as biocatalysts as they are readily available and are easily handled. They are stable, do not require co-enzymes and will often tolerate organic solvents. “Their potential for regioselective and especially for enantioselective synthesis makes them valuable tools�. [15] 2.7.4.5 Catalyst free transesterification Transesterification will occur without the aid of a catalyst, however at temperatures below 3000C the rate is very low. It has been said that there are, from a broad perspective, two methods to producing biodiesel and that is with and without a catalyst. The technical tools and processes for monitoring the transesterification reactions like TLC, GC, HPLC, GPC, H NMR and NIR should be noted. In addition, biodiesel or fuel properties and specifications by different countries should be noted. 2.8 Variables affecting transesterification reaction The process of transesterification is affected by various factors depending upon the reaction condition used. The effects of these factors are described below. 2.8.1 Effect of free fatty acid and moisture The free fatty acid and moisture content are key parameters for determining the viability of the vegetable oil transesterification process. To carry the base catalyzed reaction to completion; a free fatty acid (FFA) value lower than 2% is needed [xxxx]. The higher the acidity of the oil, smaller is the conversion efficiency. Both, excess as well as insufficient amount of catalyst may cause soap formation [32]. The triglycerides should have lower acid value and all material should be substantially anhydrous. The addition of more sodium hydroxide catalyst compensates for higher acidity, but the resulting soap causes an increase in viscosity or formation of gels that interferes in the


reaction as well as with separation of glycerol [34]. When the reaction conditions do not meet the above requirements, ester yields are significantly reduced. 2.10.2 Catalyst type and concentration Catalysts used for the transesterification of triglycerides are classified as alkali, acid, enzyme or heterogeneous catalysts, among which alkali catalysts like sodium hydroxide, sodium methoxide, potassium hydroxide, potassium methoxide are more effective

[37]

. Sodium

methoxide causes formation of several by-products mainly sodium salts, which are to be treated as waste. In addition, high quality oil is required with this catalyst

[38]

. Although

chemical transesterification using an alkaline catalysis process gives high conversion levels of triglycerides to their corresponding methyl esters in short reaction times. If the oil has high free fatty acid content and more water, acid catalyzed transesterification is suitable. The acids could be sulfuric acid, phosphoric acid, hydrochloric acid or organic sulfonic acid. The rate is comparatively much slower. Enzymatic catalysts like lipases are able to effectively catalyze the transesterification of triglycerides in either aqueous or non-aqueous systems, the by-products, glycerol can be easily removed without any complex process, and also that free fatty acids contained in waste oils and fats can be completely converted to alkyl esters. On the other hand, in general the production cost of a lipase catalyst is significantly greater than that of an alkaline one. 2.10.3 Molar ratio of alcohol to oil and type of alcohol One of the most important variables affecting the yield of ester is the molar ratio of alcohol to triglyceride. Transesterification is an equilibrium reaction in which a large excess of alcohol is required to drive the reaction to the right. For maximum conversion to the ester, a molar ratio of 6:1 should be used. However, the high molar ratio of alcohol to vegetable oil interferes with the separation of glycerol because there is an increase in solubility. When glycerol remains in solution, it helps drive the equilibrium to back to the left, lowering the yield of esters. 2.10.4 Effect of reaction time and temperature


The conversion rate increases with reaction time. Transesterification can occur at different temperatures, depending on the oil used. For the transesterification of refined oil with methanol (6:1) and 1% NaOH, the reaction was studied with three different temperatures. After 0.1 h, ester yields were 94, 87 and 64% for 60, 45 and 32.8 0C, respectively. After 1 h, ester formation was identical for 60 and 45 OC runs and only slightly lower for the 32.8 0C run. Temperature clearly influenced the reaction rate and yield of esters. 2.10.5 Mixing intensity Mixing is very important in the transesterification reaction, as oils or fats are immiscible with sodium hydroxide–methanol solution. Once the two phases are mixed and the reaction is started, stirring is no longer needed. Initially the effect of mixing on transesterification of beef tallow was study by Ma et al. No reaction was observed without mixing and when NaOH–MeOH was added to the melted beef tallow in the reactor while stirring, stirring speed was insignificant. Reaction time was the controlling factor in determining the yield of methyl esters. This suggested that the stirring speeds investigated exceeded the threshold requirement of mixing. 2.10.6 Effect of using organic co-solvents In order to conduct the reaction in a single phase, cosolvents like tetrahydrofuran, 1,4dioxane and diethyl ether were tested. Although, there are other cosolvents, initial study was conducted with tetrahydrofuran. At the 6:1 methanol–oil molar ratio the addition of 1.25 volume of tetrahydrofuran per volume of methanol produces an oil dominant one phase system in which methanolysis speeds up dramatically and occurs as fast as butanolysis. In particular, THF is chosen because its boiling point of 67.80C is only two degrees higher than that of methanol. Therefore at the end of the reaction the unreacted methanol and THF can be co-distilled and recycled. 2.11 Purification of biodiesel: Purification of biodiesel is necessary because of: • Corrosion of fuel injectors (water, catalyst) • Elastomeric seal failures (methanol)


• Fuel injector blockages (glycerin, soaps etc) • Increased degradation of engine oil • Pump seizures due to high viscosity at low temperatures • Corrosion of fuel tanks (excess water, catalyst) • Bacterial growths and clogging of fuel lines/filters Purification of biodiesel includes: (a) Separation of biodiesel Once the reaction is complete, two major products exist: glycerol and biodiesel. Each has a substantial amount of the excess methanol that was used in the reaction. The reacted mixture is sometimes neutralized at this step if needed. Glycerol separation: The glycerol phase is much denser than biodiesel phase and the two can be gravity separated with glycerol simply drawn off the bottom of the settling vessel. In some cases, a centrifuge is used to separate the two materials faster. Alcohol Removal: Once the glycerol and biodiesel phases have been separated, the excess alcohol in each phase is removed with a flash evaporation process or by distillation. In others systems, the alcohol is removed and the mixture neutralized before the glycerol and esters have been separated. In either case, the alcohol is recovered using distillation equipment and is re-used. Care must be taken to ensure no water accumulates in the recovered alcohol stream. (b) Washing of biodiesel Once separate major by-product then the methyl esters are not classified as biodiesel until the proper specifications are met because of impurities and contaminants include free glycerin, soap, metals, excess methanol, catalyst, moisture, FFA etc are not properly removed. There are many processes for washing biodiesel. These are:


i) The Wet Wash Process: Generally in this process, once separated from the glycerol, the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage.

Fig: 2.7 Washing methyl ester using wate ii) The Dry Wash Process: In this process, magnesol used as a washing agent to wash methyl ester successfully. 2.12 Fuel properties and specification of biodiesel The properties of fuel briefly in the following description: Density: The density of a material is defined as its mass per unit volume. The symbol of density is ρ (the Greek letter rho). A common laboratory device for measuring fluid density is a pycnometer. The SI unit for density is kilograms per cubic meter (kg/m³), Metric units outside the SI kilograms per litre (kg/L), kilograms per cubic decimeter (kg/dm³), grams per millilitre (g/mL), grams per cubic centimeter (g/cc or g/cm³). Viscosity: Viscosity refers to the thickness of the oil, and is determined by measuring the amount of time taken for a given measure of oil to pass through an orifice of a specified size. Viscosity affects injector lubrication and fuel atomization. Fuels with low viscosity may not provide


sufficient lubrication for the precision fit of fuel injection pumps, resulting in leakage or increased wear. Fuel atomization is also affected by fuel viscosity. Diesel fuels with high viscosity tend to form larger droplets on injection which can cause poor combustion, increased exhaust smoke and emissions. Kinematic viscosity: The resistance to flow of a fluid under gravity”. The kinematic viscosity = viscosity/density. The kinematic viscosity is a basic design specification for the fuel injectors used in diesel engines. Dynamic viscosity: Ratio between applied shear stress and rate of shear of a liquid. Flash point: The flash point is defined as the “lowest temperature corrected to a barometric pressure of 101.3 kPa (760 mm Hg), at which application of an ignition source causes the vapors of a specimen to ignite under specified conditions of test.” This test, in part, is a measure of residual alcohol in the B100.The flash point is a determinant for flammability classification of materials. The typical flash point of pure methyl esters is > 200 ° C, classifying them as “nonflammable”. However, during production and purification of biodiesel, not all the methanol may be removed, making the fuel flammable and more dangerous to handle and store if the flash point falls below 130ºC. Excess methanol in the fuel may also affect engine seals and elastomers and corrode metal components. Pour point: The pour point of a liquid is the lowest temperature at which it will pour or flow under prescribed conditions. It is a rough indication of the lowest temperature at which oil is readily pumpable. Also, the pour point can be defined as the minimum temperature of a liquid, particularly a lubricant, after which, on decreasing the temperature, the liquid ceases to flow. [1]

Acid value: Acid value (or "neutralization number" or "acid number" or "acidity") is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance. The acid number is a measure of the amount of carboxylic acid groups in a chemical compound, such as a fatty acid, or in a mixture of compounds. In a typical procedure, a known amount of sample dissolved in organic solvent is titrated with a solution


of potassium hydroxide with known concentration and with phenolphthalein as a color indicator. The acid number is used to quantify the amount of acid present, for example in a sample of biodiesel. It is the quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize the acidic constituents in 1 g of sample.

Veq is the amount of titrant (ml) consumed by the crude oil sample and 1ml spiking solution at the equivalent point, beq is the amount of titrant (ml) consumed by 1 ml spiking solution at the equivalent point, and 56.1 is the molecular weight of KOH.[1] Carbon residue: In petroleum products, the part remaining after a sample has been subjected to thermal decomposition...� is the carbon residue. The carbon residue is a measure of how much residual carbon remains after combustion. The test basically involves heating the fuel to a high temperature in the absence of oxygen. Most of the fuel will vaporize and be driven off, but a portion may decompose and pyrolyze to hard carbonaceous deposits. This is particularly important in diesel engines because of the possibility of carbon residues clogging the fuel injectors. Caloric value: The heating value or calorific value of a substance, usually a fuel or food, is the amount of heat released during the combustion of a specified amount of it. The calorific value is a characteristic for each substance. It is measured in units of energy per unit of the substance, usually mass, such as: kcal/kg, kJ/kg, J/mol, Btu/m³. Heating value is commonly determined by use of a bomb calorimeter. The heat of combustion for fuels is expressed as the HHV, LHV, or GHV: Sulfur content: The percentage by weight, of sulfur in the fuel Sulfur content is limited by law to very small percentages for diesel fuel used in on-road applications.


Biodiesel generally contain less than 15ppm sulfur. ASTM D 5453 test is a suitable test for such low level of sulfur. ASTM D 2622 used for sulfur determination of diesel fuels gives falsely high results when used for biodiesel. More work is needed to assess suitability of ASTM D 2622 application to B20 biodiesel blend. The increase in

oxygen content of the

fuel affects precision of this test method. Water content: Biodiesel and its blends are susceptible to growing microbes when water is present in fuel. The solvency properties of the biodiesel can cause microbial slime to detach and clog fuel filters. Cetane number: The cetane number is “a measure of the ignition performance of a diesel fuel obtained by comparing it to reference fuels in a standardized engine test.� Cetane for diesel engines is analogous to the octane rating in a spark ignition engine – it is a measure of how easily the fuel will ignite in the engine. Cetane number of a diesel engine fuel is indicative of its ignition characteristics. Higher the cetane number better it is in its ignition properties. Cetane number affects a number of engine performance parameters like combustion, stability, drivability, white smoke, noise and emissions of CO and HC. Biodiesel has higher cetane number than conventional diesel fuel. This results in higher combustion efficiency and smoother combustion. Ash content: Ash Percentage - Ash is a measure of the amount of metals contained in the fuel. High concentrations of these materials can cause injector tip plugging, combustion deposits and injection system wear. The ash content is important for the heating value, as heating value decreases with increasing ash content. Ash content for bio-fuels is typically lower than for most coals, and sulfur content is much lower than for many fossil fuels. Unlike coal ash, which may contain toxic metals and other trace contaminants, biomass ash may be used as a soil amendment to help replenish nutrients removed by harvest.


Table: 2.8 Fuel properties of commercial diesel and biodiesel. Fuel Standard ASTM D975 ASTM D6751 Fuel Property

Diesel

Biodiesel

~129,050 1.3-4.1

~118,170 4.0-6.0

Specific Gravity kg/l at 600F

0.85

0.88

Density, lb/gal at 150C

7.079

7.328

Water and Sediment, vol% Carbon, wt % Hydrogen, wt % Oxygen, by dif. Wt% Sulfur, wt%

0.05 max 87 13 0 0.05max

0.05 max 77 12 11 0.0 to 0.0024

Boiling Point, 0C

180 to 340

315 to 350

60 to 80

100 to 170

-15 to 5

-3 to 12

-35 to -15 40-55 2000-5000 300-600

-15 to 10 48-65 >7000 <300

Lower Heating Value, Btu/gal Kinematic Viscosity, at 400C

0

Flash Point, C 0

Cloud Point, C 0

Pour Point, C Cetane Number Lubricity SLBOCLE, grams Lubricity HFRR, microns

Sulfur content for on-road fuel will be lowered to 15 ppm maximum in 2009.

2.13 Advantages of biodiesel Key Advantages of Biodiesel: 1. Biodiesel is the only alternative fuel that runs in any conventional, unmodified diesel engine. 2. Cetane number is significantly higher than that of conventional diesel fuel.


3. Biodiesel can be used alone or mixed in any ratio with petroleum diesel fuel. The most common blend is a mix of 20% biodiesel with 80% petroleum diesel, or "B20." 4. The lifecycle production and use of biodiesel produces approximately 80% less carbon dioxide emissions, and almost 100% less sulfur dioxide. Combustion of biodiesel alone provides over a 90% reduction in total unburned hydrocarbons, 75-90% reduction in aromatic hydrocarbons and significant reductions in particulates and carbon monoxide than petroleum diesel fuel. 5. Biodiesel has 11% oxygen by weight and contains no sulfur. The use of biodiesel can extend the life of diesel engines because it is more lubricating than petroleum diesel fuel. 6. Biodiesel is safe to handle and transport because it is as biodegradable- 95% degradation in 28 days, where as diesel fuel degrades 40% in 28 days. 10 times less toxic than table salt, and has a high flashpoint of about 125째C compared to petroleum diesel fuel, which has a flash point of 55째C. 7. Biodiesel can be made from domestically produced, renewable oilseed crops such as soybeans, canola, cotton seed and mustard seed, has Positive impact on agriculture. When burned in a diesel engine, biodiesel replaces the exhaust odor of petroleum diesel with the pleasant smell of popcorn or french fries. 2.14 Utilization of by-products: The cost of biodiesel production can be reduced by proper utilization of by-products such as crude glycerin and seed cake apart from improving trans-esterification process. Crude glycerin from biodiesel contains some peculiar impurities and may not be suitable to process according to the usual technologies to produce pharmaceutical or top grade product. There is a need not only to develop purification technology for crude glycerol but also for its utilization as a raw material for the production of other chemicals as large quantity. There is a need to find the use of meal cake, which will be available in large quantities. Meal cake may be used as fertilizer, as cattle feed after detoxification, etc.


Glycerin Utilization for Specific Products An effective usage or conversion of crude glycerol to specific products will cut down the biodiesel production costs.

Glycerol,

when

used

in

combination with other compounds yields other useful products. For example glycerol and ethylene glycol together can be used as a solvent for alkaline treatment of poly fabrics. Glycerol reductions with magnesium synthesize the carbon anions.

Fig: 2.8 Glycerin

Glycerol can be used as dielectric medium for compact pulse power systems. Glycerol acts as a medium in electrodeposition of Indium-Antimony alloys from chloride tartrate solutions. Biomass is converted to liquid fuel using glycerol that can be blended with gasoline as an alternative fuel. Mixed culture fermentation of glycerolsynthesizes short and medium chain polyhydroxyalkanoate blends.


2.15 Emission Biodiesel is the first and only alternative fuel to have a complete evaluation of emission results and potential health effects submitted to the U.S. Environmental Protection Agency (EPA) under the Clean Air Act Section 211(b). These programs include the most stringent emissions testing protocols ever required by EPA for certification of fuels or fuel additives in the US. The overall ozone (smog) forming potential of biodiesel is less than diesel fuel. The ozone forming potential of the speciated hydrocarbon emissions was nearly 50 percent less than that measured for diesel fuel. The data gathered through these tests complete the most thorough inventory of the environmental and human health effects attributes that current technology will allow. A survey of the results is provided in the table below. Table: 2.9 Biodiesel emission compared to commercial diesel Emission Type

B100

B20

Total Unburned Hydrocarbons

-93%

-30%

Carbon Monoxide

-50%

-20%

Particulate Matter

-30%

-22%

Nox

+13%

+2%

Sulfates

-100%

-20%*

PAH (Polycyclic Aromatic Hydrocarbons)**

-80%

-13%

nPAH (nitrated PAHâ&#x20AC;&#x2122;s)**

-90%

-50%***

Ozone potential of speciated HC

-50%

-10%

Regulated

Non-Regulated


* Estimated from B100 result ** Average reduction across all compounds measured *** 2-nitroflourine results were within test method variability Sulfur: Sulfur emissions are essentially eliminated with pure biodiesel. The exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel were essentially eliminated compared to sulfur oxides and sulphates from diesel. Criteria pollutants are reduced with biodiesel use. The use of biodiesel in an unmodified Cummins N14 diesel engine resulted in substantial reductions of unburned hydrocarbons, carbon monoxide, and particulate matter. Emissions of nitrogen oxides were slightly increased. Carbon Monoxide: The exhaust emissions of carbon monoxide (a poisonous gas) from biodiesel were 50 percent lower than carbon monoxide emissions from diesel. Particulate Matter: Breathing particulate has been shown to be a human health hazard. The exhaust emissions of particulate matter from biodiesel were 30 percent lower than overall particulate matter emissions from diesel. Hydrocarbons: The exhaust emissions of total hydrocarbons (a contributing factor in the localized formation of smog and ozone) were 93 percent lower for biodiesel than diesel fuel. Nitrogen Oxides: NOx emissions from biodiesel increase or decrease depending on the engine family and testing procedures. NOx emissions (a contributing factor in the localized formation of smog and ozone) from pure (100%) biodiesel increased in this test by 13 percent. However, biodieselâ&#x20AC;&#x2122;s lack of sulfur allows the use of NOx control technologies that cannot be used with conventional diesel. So, biodiesel NOx emissions can be effectively managed and efficiently eliminated as a concern of the fuelâ&#x20AC;&#x2122;s use.


Biodiesel reduces the health risks associated with petroleum diesel. Biodiesel emissions showed decreased levels of PAH and nitrited PAH compounds which have been identified as potential cancer causing compounds. In the recent testing, PAH compounds were reduced by 75 to 85 percent, with the exception of benzo(a)anthracene, which was reduced by roughly 50 percent. Targeted nPAH compounds were also reduced dramatically with biodiesel fuel, with 2-nitrofluorene and 1-nitropyrene reduced by 90 percent, and the rest of the nPAH compounds reduced to only trace levels[1] 2.16 Performance of biodiesel in diesel engine Conventional Internal Combustion Engines can be operated with biodiesel without major modification [61]. In comparison to diesel, the higher cetane number of biodiesel results in shorter ignition delay and longer combustion duration and hence results in low particulate emissions and minimum carbon deposits on injector nozzles. It is reported that if an engine is operated on biodiesel for a long time, the injection timing may be required to be readjusted for achieving better thermal efficiency

[62]

. Various

blends of biodiesel with diesel have been tried, but B-20 (20% biodiesel + 80% diesel) has been found to be the most approximate blend. Further studies have revealed that biodiesel blends lead to a reduction in smoke opacity, and emissions of particulates, unburnt HCS, CO2 and CO, but cause slightly increase in nitrogen oxides emission

[63]

. All the blends have a higher thermal efficiency than diesel and so give

improved performance. A concentration of 20% biodiesel gave maximum improvement in peak thermal efficiency, minimum break specific energy consumption and minimum smoke opacity. Hence, B-20 was recommended as the optimum blend for long-term engine operation [64]. 2.17 The global market for biodiesel The global market for biodiesel is poised for explosive growth in the next ten years (Figure 4.2). Although Europe currently represents 90% of global biodiesel consumption and production, the U.S. is now ramping up production at a faster rate than Europe, and Brazil is expected to surpass U.S. and European biodiesel production by the year 2015. It is possible that biodiesel could represent as much as 20% of all on-road diesel used in Brazil, Europe, China and India by the year 2020.


In the USA, the market for biodiesel is growing at an alarming rate. Biodiesel consumption in the U.S. grew from 25 million gallons per year in 2004 to 78 million gallons in 2005. Biodiesel production in the U.S. is expected to reach 300 million gallons by the end of 2006, and to reach approximately 750 million gallons per year in 2007 (Figure 4).

Fig: 2.9 World biodiesel production and capacity. Increasing environmental concerns and the need for energy independence have led to the biodiesel market. Despite the economic recession, global biodiesel production totaled 5.1 billion gallons in 2009, representing a 17.9% increase over 2008 levels. The biodiesel market is expected to grow from $8.6 billion in 2009 to $12.6 billion in 2014. Market growth is primarily dependent on the availability, quality, and yield of feedstock, as it accounts for 65% to 70% of the cost of biodiesel production. Biodiesel derived from rapeseed oil forms the largest segment of the overall market. Germany is the single largest producer of biodiesel with 2.8 million tons produced in 2008. Transportation forms the main application market for biodiesel, with automotives accounting for 70% of the global biodiesel production. As the use of conventional fuel


for transport purposes is increasing greenhouse gas emissions at an alarming rate, governments across the globe have begun providing incentives for green energy. Europe is currently the world's largest biodiesel market; and is expected to be worth $7.0 billion by 2014 with a CAGR of 8.4% from 2009 to 2014. The growth of the European biodiesel market is driven mainly by governmental initiatives. 2.18. Cost of biodiesel:

Fig: 2.10 Cost estimation of biodiesel production. 2.19 The aim of current research work 1. Biodiesel presents a suitable renewable substitute for petroleum based diesel. With the exception of hydroelectricity and nuclear energy, the majority of the worlds energy needs are supplied through petrochemical sources, coal and natural gas. All of these sources are finite and at current usage rates will be consumed by the mid of this century. The depletion of world petroleum reserves and increased environmental concerns has stimulated recent interest in alternative sources for petroleum-based fuels. Biodiesel has arisen as a potential candidate for a diesel substitute due to the similarities it has with petroleum-based diesel.

2. As the production of biodiesel from edible oils is currently much more expensive than diesel fuels due to relatively high cost of edible oils. There is


excessive demand of it for edible purpose and need to explore non-edible oil sources as alternative feed stock for the production of biodiesel. Rubber seed oil is easily available in many parts of the world including Bangladesh and are very cheap compared to other sources.

3. Rubber seed oil is waste product of rubber plantation and available in abundance in Bangladesh. This is even a problem for the rubber plantation, as its contained oil hampers the fertility of the garden soil.

4. Literature review shows that the yield of Rubber seed oil percentage (38.9%) extracted is competitive to other non-edible seeds like Jatropha (32.4%), Karanja (31.8%), and others. [20]

5. In our country, there is no reserve / source of petroleum base diesel. So, we can find out alternative sources.

6. Europe is using biodiesel for more than 20 years. Developed countries searching for new resources of renewable energy have emphasized on increasing the production and consumption of renewable fuels like biodiesel. Whilst, biodiesel consumption in Bangladesh is 0.

7. No other source of non edible vegetable oil is more dependable for biodiesel production than rubber seed oil. For any other source we have to go for plantation first, i.e. a huge task. But there is the existing source, quite unused and unnoticed, rubber seeds from huge plantation areas of rubber garden.

8. Rubber production is a profitable sector for Bangladesh. If we can turn these seed into some substance of value it will add an extra profit.


9. Co-ignition of Rubber seed oil biodiesel with commercial diesel will reduce the demand of fossil diesel and thus we can save a lot of foreign exchange. So, the ultimate purposes of this study are, a) Extraction of rubber seed oil from collected rubber seed. b) Optimization of biodiesel Production process from Rubber seed oil. c) Determinations and comparisons of properties of produced biodiesel with commercial diesel. d) To evaluate the co-ignition characteristics of Rubber seed oil biodiesel with commercial diesel 3.1 Extraction of rubber seed oil Rubber seed oil was extracted in two process; 1. The solvent extraction process, using petroleum spirit of boiling range 44 to 80 oc with the means of a soxhlet set-up. 2. The mechanical expeller was used, from a local region normally used for edible oil extraction. Materials: 1. Rubber seed 2. Solvent; Petroleum ether (boiling range 45~80 OC) 3. Soxhlet set-up with electric heater. 4. Mechanical expeller.

Fig: 3.1 Rubber seed


Fig: 3.2 Oil extraction set up (left: Soxhlet; right: Mechanical expeller) A schematic diagram for the extraction of crude rubber seed oil (CRSO) from rubber seed:

Rubber seed collection

Sun drying and sorting

Crushing by Expeller

Shell removal

Roasting for 10 minutes Crude RS oil Solvent extraction

Distillation to solvent recovery

Crude RS oil


Fig: 3.3 Flow chart for extraction of oil from Rubber seeds. 3.2 Biodiesel production from rubber seed oil 3.2.1 Raw materials: a. Rubber seed oil b. Methanol c. Catalyst-H2SO4, NaOH d. Chemicals & reagent a. Crude rubber seed oil: Crude rubber seed oil (Hevea brasiliensis) oil was used as a raw material to produce bio diesel. Rubber seed was collected from Ispahani Neptune Ltd, Chittagong. Oil was extracted by a mechanical expeller used locally for edible oil extraction. Bulk oil was collected from Sontoshpur Rubber Estate, Madhupur, Tangail. It was almost one year old. Although the oil was stored in tightly closed plastic container, a certain percentages of degradation is expected. It was well settled and filtered before biodiesel production. Fig: 3.4 Crude rubber seed oil b. Methanol: Methanol (CH3OH) was used as a raw material in the trans-esterification reaction which was 99.8% pure, HPLC grade, 0.2 um membrane filtered. Refractive index 1.326-1.33. maximum water content 0.05 %. c. Catalyst:


NaOH was used as catalyst which was of Merck, Germany grade. Assay (acidimetric) 98-100.5 %.

d. Reagents & Chemicals used for the production and analysis of biodiesel i) Iso-propanol ii) NaOH solution iii) Titration solvent (Toluene+Iso-propanol) iv) Indicator (p-Naphtholbenzoin) v) Bromine water vi) Barium Chloride vii) HCl 3.2.2 Apparatus: Chemicals used for the production and analysis of biodiesel i) Magnetic stirrer ii) Two neck round bottom flux iii) Small tube with magnetic Stirrer iv) Viscometer v) Picnometer vi) Diesel Analyzer vii) Flash point apparatus viii)

Pour point appartus

ix) Bomb calorimeter x) Diesel Engine 3.2.3 Experimental setup for biodiesel production


Fig: 3.5 Set up for biodiesel production.( left: Lab Scale, right: large sclale) A schematic diagram for the production of Biodiesel from Rubber seed (Hevea brasiliensis) oil:

Fig: 3.6 Schematic diagram of Biodiesel production technology. 3.3 PROCEDURE: 3.3.1 Screening of waste fried oil Crude rubber seed oil collected from different restaurant and canteen of university hall was primarily screen for removing dirt, mud of oil. Finally it was screened by 10 mesh screening plate. 3.3.2 Acid value Estimation:


Fig: 3.7 estimation of acid value Acid value is defined as â&#x20AC;&#x153;The number of milligram of potassium hydroxide required to neutralize the 1gm of oil or fatâ&#x20AC;?. In the first stage, the acid value of the reaction mixture was determined by a standard acid base titration method (ASTM, 2003) where a standard solution of one mol KOH solution was used. 100 ml solution of mixture (toluene + isopropyl alcohol + H 2O) was added to 1-5 gm of sample in the present of 2/3 drop p-benzoin indicator. Titration was done between 0.1 M KOH and solution mixture. A.V =

3.3.3 Dual steps process 3.3.3.1 Acid catalyzed esterification- first step in biodiesel production


Fig: 3.8 Left-Acid esterification; Right- Methanol layer seperation Preparation: a. At first the amount of water and % of FFA of the oil were determined. Free fatty acid level or water level being too high might cause problems with soap formation (saponification) and the separation of the glycerin by-product. Esterification process carried out due to the high FFA (near 35%) of crude rubber seed oil.

b. Catalyst( H2SO4) was dissolved in the alcohol using a standard agitator or mixer. c. The alcohol/catalyst mix was then charged into a closed reaction vessel and raw oil is added. The reaction temperature was kept under boiling point of methanol and standard condenser was equipped to prevent the loss of alcohol. In this process, oil was treated with acid catalyst (H2SO4 2.25% x FFA %) [14] .


d. Reaction conditions set for this experiment were temperature 64 0C, agitation rate 400rpm and time 1 hr. After one hour of reaction, the mixture was allowed to settle for 1 h and the methanolâ&#x20AC;&#x201C;water-catalyst fraction from the top layer was removed.

e. The resultant oil FFA % was reduced to less than 1 % and was quite appropriate to go for the next step transesterification reaction.

3.3.3.2 Base catalyzed transesterification- second step in biodiesel production

Fig: 3.9 Base catalyzed rans-esterification. a. Preparation: At first the amount of water and % of FFA of the oil are determined, that should be less than 1% [14] b. Catalyst (NaOH) was dissolved in the alcohol using a standard agitator in little warm condition. c. Raw oil was added. The system from there on was apparently closed to prevent the loss of alcohol.


d. The reaction mixture is kept just below the boiling point of the alcohol (around 64 째C) to avoid escape of alcohol and maintain atmospheric pressure. Recommended reaction time varies from 1 to 2 hours; under normal conditions the reaction rate will double with every 10 째C increase in reaction temperature. Excess alcohol was normally used to ensure total conversion of the oil to its esters. e. The glycerin phase is much denser than biodiesel phase and the two can be separated under gravity with glycerin simply drawn off the bottom of the settling vessel. In some cases, a centrifuge was used to separate the two materials faster. f. Once the glycerin and biodiesel phases have been separated, the excess alcohol in each phase is removed with a flash evaporation process or by vacuum distillation. In other systems, the alcohol is removed and the mixture neutralized before the glycerin and esters have been separated. In either case, the alcohol is recovered using distillation equipment and is re-used. g. The glycerin by-product contains unused catalyst and soaps that are neutralized with an acid and sent to storage as crude glycerin (water and alcohol are removed later, chiefly using evaporation, to produce 80-88% pure glycerin). h. Once separated from the glycerin, the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage.

3.4 Optimization of biodiesel production The above procedure was followed in the production of biodiesel and optimization of the process condition. Experiments were carried out using two type reactors. These are:


i) Small scale reaction tube with magnetic stirrer ii) Two neck round bottom flax with stirrer. iii) 500 ml round bottom flask

i)

Biodiesel production using small scale reaction tube with magnetic stirrer

Small size tubes with stirrer were used to perform the experiment. The optimization step is divided into two parts. These are: (1) Variation of oil to mehanol ratio (2) Variation of catalyst concentration. (1) Variation of catalyst concentration. In this process, 4 tubes were taken. Tubes were filled with different weiftt of catalyst with constant weight of oil and methanol. After the completion of the transesterfication, product yield was measured.

Fig: 3.10 Effect of variation catalyst concentration on product yield.

(2) Variation of oil to methanol ratio: In this process, 4 tubes were taken. Tubes were filled with different amount of methanol and in fixed amount of oil and catalyst. After the completion of the transesterfication, product yield was measured


Fig: 3.11 Effect of variation of oil to methanol ratio on biodiesel yield. ii) Two neck round bottom flux with stirrer When optimization completed in a small scale, then transesterification were carried out in a two neck round bottom flux.

Fig: 3.12. Esterification in the reactor after addition of methanol and acid catalyst The experimental setup is shown in figure. Two-necked round-bottomed flask was used as a reactor. The flask was placed in a water bath on a electric heater with regulated magnetic stirring mechanism, whose temperature could be controlled within + 20c. One of the two side necks was equipped with a condenser and the other was used as a thermo well. A thermometer was placed in the thermo well containing little


glycerol for temperature measurement inside the reactor. A magnetic stirrer was put inside the flask. 3.5 Separation and purification of biodiesel: After completion of reaction, methyl ester was separated from mixture of methyl ester and glycerin. Methyl ester was separated by separating funnel and established the layer of 16 hours.

Biodiesel

Glycerin

Fig: 3.13 Separation of Biodiesel (methyl ester). After separation, the properties of the produced Biodiesel were determined the laboratory method.


Fig: 3.14 Biodiesel from fried rubber seed oil (left: Before washing Right: after washing).

3.6 Methods used for the determination of the physicochemical properties of Biodiesel (methyl ester): To determine the properties of the biodiesel produced from rubber seed oil, different ISO standard methods were used. Below table showing the name of the different standard methods that were used for properties determination. Table: 3.1 ISO standard methods that were used for the determination of the properties of biodiesel: Name of the analysis Density at 150C Kinematic viscosity, 400C, cSt Kinematic viscosity, 1000C, cSt Pour point, 0C Flash point,0C Acid value, mg KOH/g Sulfur content, %mass Cetane no. Water content, % Carbon residue, % Ash content, %

Method IP-160/57 ASTM-D 445-65 ASTM-D 445-65 ASTM-D 97-57 ASTM-D 93-62 IP-1/58 ASTM-D 129-64 ASTM-D 613-86 IP-74/57 ASTM-D 189-65 ASTM-D 482-63


ASTM- American Standard Testing Method (USA), IP- Institute of Petroleum, UK. 3.7 Characteristics determination and instruments specifications: Balance: SCIENTECH, Boulder. Com USA, Model no. SA 210; Weighing range 30gm, readability 0.1 mg, precision +/0.1 mg, taring range 30 gm.

Fig: 3.15 Balance

Viscometer: Canon-Fenske routine viscometer, Jena glass Duran. For absolute measurement with printed on constant according to ASTM D 2515, ISO/DIS 3105. Range (0.4 -20000 cSt/ mm2s-1) Color comparator: According to ASTM D 1500, for visual

Fig: 3.16 viscometer

determination of color of diesel fuel oils, lube oils and waxes. Comprising standardized light source as specified, cylindrical glass jars for the sample and a circular turret containing the 16 color conforming the colorimetric co-ordinates of D 1500. Test requires 2 cells 13.5 mm path length. One for sample, one for blank.

Fig: 3.17 Color comparator


Calorimeter: Model- Julius Peters, Berlin-NW 21. For determining calorific value, of liquid and solid fuels, acc. To ASTM and DIN 51900 (Bethelot method). Double walled water container, including stirring motor with stirrer, wide field reading eye lenses. All controls are mounted, suitably insulated.

Flash point tester:

Fig: 3.18 Bomb calorimeter

BOIKEL, model no 152800. It is used to determine Flash point and fire point of liquid fuel samples over a reasonable range. A thermometer with a range of 360oc, the measurements can be operated manually.

Fig: 3.19 Flash point testing machine

Furnace: Carbolite Furnaces, Bamford, England.

Control of temperature is quite manual

Maximum range 1100OC.

with highly refractory material built.


Fig: 3.20 Furnace

TGA analyser: Thermogravimetric analysis or thermal gravimetric analysis (TGA) is a type of testing performed on samples that determines changes in weight in relation to change in temperature. TGA is commonly employed in research and testing to determine characteristics of materials to determine degradation temperatures, Fig: 3.21 TGA analyser.

absorbed moisture content of materials, the level of inorganic and organic components in materials, decomposition points, and solvent residues. Simultaneous TGA-DTA measures both heat flow and weight changes (TGA) in a material as a function of temperature or time in a controlled atmosphere.


The DTA curves show the effect of energy changes (endothermic or exothermic reactions) in a sample. The TG curves ideally show only weight changes during heating. The derivative of the TG curve, the DTG curve, shows changes in the TG slope that may not be obvious from the TG curve. Thus, the DTG curve and the DTA curve may show strong similarities for those reactions that involve weight and enthalpy changes. A derivative weight loss curve can identify the point where weight loss is most apparent. Again, interpretation is limited without further modifications and deconvolution of the overlapping peaks may be required. 4.1. Physical characteristics of Rubber seed: Rubber seed comes from a 3 seeded ellipsoidal capsule, each carpel of fruit bears 1 seed. Color

: Mottled brown

Dimension

: 2.1-3 cm x 1.8-2 cm

Weight

: 2-4 gm each

Kernel (endosperm, wt %)

: 52% apx.

Oil content

: 25.18 % (w/w of seed)

4.2. Crude rubber seed oil extraction Rubber seed were well-dried, decorticated before to be powdered and screened to homogeneous size.


Table: 4.1. Extraction of rubber seed oil in solvent extraction method. Sample

Solvent,

Solvent

Oil

Oil

Oil

weight

ml

recovered,

extracted

volume

content

gm

ml

wt. %

ml

Time hours

87.0030

800

420

21.6689

23.95

24.91

1

85.4241

800

345

28.1671

31.13

32.97

1

99.7364

600

320

44.2030

48.86

44.32

1

85.6348

600

235

43.1432

47.69

50.38

2:30

36.7771

500

370

14.71

16.26

39.98

2:30

45.7945

400

355

21.98

24.29

48

2:30

29.0465

300

170

14.1663

15.66

48.77

2:30

Extraction by mechanical expeller: Seed weight

: 13.60 kg

Decorticated seed weight

: 800kg apx.

Oil extracted

: 1.5 kg (%)

Oil extracted from Cake by solvent : 21.5134 gm/100gm 4.3. Physicochemical properties of RSO


Fig: 4.1 color variation in oil (Left) 1, 2, 3 and biodiesel (Right)

The fig: 4.1, shows the color variation from left to right. Leftmost S1 is the solvent extracted oil, then E1 expeller extracted oil, third from left E2 is the oil used for the experiment and collected in bulk. The rightmost B is the biodiesel produced from E2.


Table: 4.2. Properties of rubber seed oil are given bellow: Name of the

Method

RSO

analysis Solvent extracted Color

ASTM & DIN

Expeller 1

Expeller 2

3

2.5

4.5

IP-160/57

0.9047

-

0.9319

51900 Density at 150C, g/cc Kinematic

400C

ASTM-D 445-65

20.5933

-

44.7912

viscosity,

1000C

ASTM-D 445-65

6.5736

-

9.5192

Pour point, 0C

ASTM-D 97-57

-8

-6

4.5

Flash point,0C

ASTM-D 93-62

-

86

60

Fire point. 0C

ASTM-D 93-62

-

-

66

Acid value, mg

IP-1/58

56.8

24.45

5.49

ASTM-D 129-64

0.003062

-

0.02719

ASTM-D 613-86

-

-

38.5

Water content, %

IP-74/57

Nil

-

Trace

Carbon residue, %

ASTM-D 189-65

-

-

Ash content, %

ASTM-D 482-63

0.0006703

-

0.05163

Calorific value,

-

11253.652

-

9956.1534

cSt

KOH/g Sulfur content, g/g Cetane no.

Kcal/kg


* RSO = Crude rubber seed oil

4.4. Optimization of biodiesel production process Biodiesel is produced using Rubber seed oil by transesterification process. The physical & chemical properties of Rubber seed oil, effect of change of molar ratio of limiting reactants (methanol), catalyst (NaOH) and reaction duration were determined. Product (Biodiesel) was analyzed for its confirmation. The details of the above are described below. 4.4.1 Effect of change of molar ratio of limiting reactants 4.4.1.1 Biodiesel production using small tube with stirrer: Trasesterification is carried out in small scale with the help of 20ml measured test tube with stirrer. Here amount of catalyst was kept fixed 0.5% to oil. Table: 4.3. The effect of variation of oil to methanol ratio on product yield. Exp. No.

RSO

methanol

catalyst

Methanol

Product

to oil molar (gm)

(gm)

wt.%

ratio

Yield% (gm)

1.

2.00

0.2055

3:1

1.533

76.65

2.

2.00

0.3090

4.5:1

1.6962

84.81

3.

2.00

0.600

6:1

1.7048

85.24

4.

2.05

0.500

7.5:1

1.6364

79.82

0.5

* RSO = Crude rubber seed oil From the table: 4.3, it is found that with the increase of molar ratio of methanol to oil, the yield biodiesel increase upto 85%, when molar ratio is 6:1. Again with the increase of molar ratio, the yield decreases. Catalyst (NaOH) was kept fixed to 0.5% of RSO for above experiment which is shown in the following graph.


% Yields

Wt. of methanol

Fig: 4.2: Effect of variation of oil to methanol ratio on product yields curve.

Table: 4.4 The effect of variation of oil to catalyst ratio on product yield. RSO Tube no.

(gm)

1. 2. 3.

Catalyst

Methanol

wt.%

(gm)

0.33 2.00

0.72 0.98

0.4

Product (gm)

Yield%

1.8204

91.02

1.8933

94.67

1.6809

84.05


4.

1.02

1.6907

84.54

* RSO = Rubber seed oil From the table: 4.4, it is found that with the increase of catalyst percentage, the biodiesel yield percentage increases gradually upto 94.6%. It is to be mentioned that the maximum yield does not ensure the maximum conversion. Fig: 4.3, shows the curve for this study. With increasing catalyst percentage the curve shows decline in product yield %. The methanol amount kept fixed to 0.4 gram for above experiment which is shown in the

% Yields

following graph.

Wt. of catalyst


Fig: 4.3 Effect of variation of oil to catalyst ratio on product yields curve.


4.4.1.2 Biodiesel production using two-neck round bottom flux with stirrer: a. Effect of variation of catalyst concentration: Table: 4.5, Variation of catalyst concentration with constant wt. of oil and methanol Exp. no.

RSO (gm)

methanol (gm)

Catalyst

product Yield

Glycerin

gm

gm

(wt. %) wt. %

wt. %

1.

0.1

2.

0.2

24.98

87.04

3.72

12.96

3.

0.3

24.69

83.58

4.85

16.42

4.

0.4

23.39

80.02

5.84

19.98

5.

0.5

21.45

75.05

7.13

24.95

6.

0.6

22.27

76.11

6.99

23.89

7.

0.7

22.85

77.58

6.59

22.42

0.8

21.71

73.54

7.81

26.46

0.9

20.45

69.79

8.85

30.20

10.

1.0

21.69

73.76

7.72

26.24

11.

1.1

20.01

69.62

8.73

30.38

12.

1.2

20.14

67.77

9.58

32.23

13.

1.5

18.45

61.54

11.53

38.46

14.

2.0

14.81

51.24

14.39

48.76

8. 9.

25

5.00

No phase separation

* RSO = Crude rubber seed oil From the table: 4.5, it is found that with the increase of catalyst concentration, the yield biodiesel shows gradual decrease to lowest 51%. The optimum value 0.7% catalyst shows the considerably high yield of 77%, as can be presumed from the figure 4.4. With the


increase in catalyst percentage to oil conversion improves but excess of it reasons for soap formation and eventually, phase separation becomes difficult taking considerable percentage of methyl ester with the bottom phase. Methanol was kept in fixed molar ratio to RSO at 6:1 for above experiment which is shown in the following graph.

% Yields

Biodiesel

Glycerin

Wt of catalyst %

Fig: 4.4 Variation of catalyst concentration curve


Fig: 4.5 yield variation for change in catalyst %


b. Effect of variation oil to methanol ratio on product yield

Fig: 4.6 yield variation for change in methanol

In Fig: 4.6, M1, M2, M3, M4 and M5 represents experiments for methanol variations of 10%, 15%, 20%, 25% and 30%.

Table: 4.6 The effect of variation oil to methanol ratio on product yield. Tube no.

RSO

Catalyst

(gm)

(wt. %)

Methanol

Product

(wt. %)

Glycerin

Yield gm

wt. %

gm

wt. %

1.

10

19.196

77.17

5.68

22.83

2.

15

19.470

78.38

5.37

21.62

20

19.150

78.87

5.13

21.13

25

19.598

77.50

6.72

22.59

3. 4.

25

0.7


5.

30

18.910

77.40

5.51

22.55

From the table: 4.6, it is found that with the increase of molar ratio of methanol to rubber seed oil, the yield of biodiesel eventually increases unto 78.87% , when methanol was in 100% excess than stoitiometric ratio. The maximum conversion could be known by GC analysis representing percentage of fatty acid methyl ester and unconverted glycerides. Catalyst (NaOH) was kept fixed to 0.7% of rubber seed oil for above experiment which is shown in the following graph.

Biodiesel

% Yields

Glycerin

Wt. of methanol

Fig: 4.7 Effect of variation of oil to methanol ratio on product yields curve


c. Effect of variation reaction time on product yield.

Fig: 4.8 yield variation for change in time

Fig: 4.8, shows the variation of biodiesel yield % with change in reaction time. T1, T2, T3 and T4 represents for time duration of 30, 60, 90 and 120 minutes consecutively. Table: 4.7 The effect of variation reaction time on product yield. Tube no.

RSO Catalyst (gm)

(wt. %)

Methanol (wt. %)

Reaction

product Yield

Glycerin

time (min)

gm

wt. %

gm

wt. %

30

21.170

73.48

7.62

26.52

60

20.620

81.28

4.75

18.72

3.

120

19.640

79.39

5.10

20.61

4.

90

22.598

77.08

6.72

22.92

1. 2.

25

0.7

20

* RSO = Crude rubber seed oil From the table: 4.7, it is found that with the increase of duration of reaction, the yield of biodiesel shows increasing phenomena, eventually increase to give maximum yield 81%


when reaction took one hours. Although, further reaction time should raise the conversion percentage, it also causes to decrease in yield %. The reason might be prolonged time of stirring, that cause problem in phase separation. Moreover, the longer duration of a reaction process is not considered feasible. Amount of all other parameters as oil, methanol, and catalyst (NaOH) was kept fixed for all four experimental run.

Biodiesel

% Yields

Glycerin

Wt. of methanol

Fig: 4.9 Effect of variation of time on product yields curve OPTIMUM CONDITIONS: The optimum condition for production of biodiesel from Rubber seed oil are summerized as follows: Molar ratio of Rubber seed oil to Methanol is 1:6 , amount of catalyst (NaOH) concentration is 0.7% of the oil, within fair reaction time of 1 hour at 65 Oc with moderate stirring rate. The optimum yield is more than 77%. d. Biodiesel production in large scale using 500 ml flask with stirrer: Table: 4.8 Bulk production of biodiesel from RSO in variable amounts.


Exp. no. Catalyst (wt. %)

Methanol( wt. %)

RSO

Biodiesel Yield

Glycerin

gm

gm

(gm) wt. %

wt. %

1.

191.61

77.78

54.71

22.22

2.

191.29

79.22

50.17

20.78

195.10

78.55

53.28

21.45

185.45

76.71

56.61

23.39

143.99

75.95

45.59

24.05

137.29

75.25

45.15

24.75

141.14

75.54

45.69

24.46

143.05

76.22

44.63

23.78

140.24

75.56

45.37

24.44

73.53

75.77

23.51

24.23

3.

200

4. 5. 6.

0.7

20

7.

150

8. 9. 10.

80

4.5 Characteristics of Biodiesel from crude rubber seed oil (CRSO) Table: 4.10 Comparison of obtained Biodiesel & commercial diesel: Name of the analysis

Method

Biodiesel

Biodiesel Standard[19,14]

Commercial diesel

Specific gravity at 150C (gm/ml)

IP-160/57

0.8897

0.88

0.8445

40 0C

D 445-65

4.48

1..9-6

6.06

Kinematic viscosity, cSt

1000C

1.912

Pour point, 0C

D 97-57

-5

-15 ~16

-2

Flash point,0C

D 93-62

66

100-170

70

Acid value, mg KOH/g

IP-1/58,

0.052

0.80 max

0.34


D 664 Sulfur content, %mass

D 129-64

0.001

0.05

0.905

Cetane no.

D 613-86

47

48-60

51

Water content, (vol%)

IP-74/57

nil

0.05

Zero

Carbon residue, wt. %

D 189-65

0.15

0.05 max

-

Ash content, %

D 482-63

0.003

0.02max

-

4.6 Engine performance studies Co-ignition characteristics test of rubber seed oil diesel with commercial diesel: Diesel oil is collected from local market and observation of co-ignition characteristics using different amount of Rubber seed oil. Results of different experiments of co-ignition are shown in the table. Table: 4.11 Co-ignition characteristics of Rubber seed oil with commercial diesel: Type

Ratio

Duration, (min)

Conventional diesel

to

Emission gas temperature (Oc)

9:1

8:37

80

8:2

11:01

81

7:3

10:14

78

6:4

10:10

77

5:5

7:57

84.5

4:6

7:48

84.5

2:8

8:54

86

100%

9:05

89

Biodiesel RS biodiesel

Observation

Running smoothly, No visible smoke, Smell better with increase of biodiesel percentage


Conventional

100%

9:02

83

diesel

Fig: 4.10, shows that the blend percentage of B20 (20% biodiesel in 80%) is most

Time

efficient in respect to time duration of fuel consumption in diesel engine.

Biodiesel % in blend

Fig: 4.10 Variation in duration for different blend %. Fig: 4.11, shows increasing phenomena in exhaust gas temperature with the increase in biodiesel percentage, except a fall for B30 and B40


Temperature Biodiesel % in blend

Fig: 4.11 Variation in emission temperature for different blend %. 4.7 FTIR analyses 4.7.1 Functional Groups identification of rubber seed oil (RSO): To determine the functional groups in RSO, we employed methods of spectroscopy: FTIR. FTIR of the products was recorded on a Perkin Elmer Spectrum GX spectrophotometer in the range 400-4000 cm-1. FTIR was used to measure functional groups of RSO. A very thin film of MRSO was applied to NaCl cells (25 mmi.d Ă&#x2014; 4 mm thickness) for analysis. Table 4: The main wavelengths in the FTIR functional groups of RSO Wavelength absorbed by RSO

3020

Functional group

C-H stretching vibration (C is part of C=C )

Fig: 4. 8 yield variation for change in time

2945

O-H stretching vibration of carboxylic


acid 2860

C-H stretching vibration (aliphatic)

1740

C=O stretching vibration (ester)

1580

C=C aromatic stretching

1365

C-H group vibration (aliphatic)

1215, 1070

C-O stretching vibration in ester

* RSO = Rubber seed oil Major peak is in the region of 1740 cm-1. FTIR spectroscopy showing the main peaks and their functional groups of the RSO (Table 4) showed characteristic strong absorption bands at 1746 cm-1 for the ester carbonyl (C=O) functional groups. 1580 is quite unexpected.


Table 4.7.2 : The main wavelengths in the FTIR functional groups of Biodiesel Wavelength absorbed by Biodiesel

Functional group

3440

O-H Stretch alcohol

2930

O-H stretch of carboxylic acid

2860

C-H Stretch Alkane

1740

C=O Stretching of ester /carboxylic acid

1450

C=C aromatic stretching

1360

C-H group vibration (aliphatic)

1180

C-O absorption in alcohol,ester

720

aromatic ring bends (for mono-sub'd ring)

Major peaks are in the region of 2930 cm-1, 1740 cm-1. FTIR spectroscopy showing the main peaks and their functional groups of the Biodiesel (Table 4.7.2) showed characteristic strong absorption bands at 1746 cm-1 for the ester carbonyl (C=O) functional groups. C=C, double bonds which appear as medium to strong absorptions in the region 1450 cm-1. The CH stretch band is much weaker than in alkenes. 4.8 Experimental results and analysis of TGA experiments: The results from TGA experiments are shown in the figures 1 and 2. Clearly a distinction is evident between two major weight-loss events. The figures 1 represents the TGA results obtained for Rubber seed oil and figures 2 represents the TGA results obtained for biodiesel from Rubber seed oil. At higher temperatures (>400째C), all materials display weight-loss, involving the breakdown of structural bonds. The similarity between the onsets of structural collapse is put in contrast with variable positions of evaporation process. Therefore in these experiments, the weight-loss could be attributed to the breakdown of structural bonds.


Figures 1 show the TGA results for Rubber seed oil and Figures 2 show the TGA results for Biodiesel produced from Rubber seed oil. The blue line records the weight-loss as a function of temperature; its derivative function is symbolized by a red line. The latter is interpreted as a signal that describes the rate of various weight-loss reactions. The green line represents the DTA curve i.e. the differential thermal analysis curve. 4.8.1 Rubber seed oil: Figure 1 shows TG/DTA measurement results of Rubber seed oil over a wide temperature range (30-600째C). DTA curve shows endothermic peak in the around of 377oC and in the around of 497oC. TG curve shows weight loss starts after 200 oC and in significant rate after 320oC. it becomes even steeper after468 oC. Maximum weight loss occurs almost 92% in the boiling range of 426 oC to 516 oC. From the results, the change which may happen in each temperature range and phenomenon which may occur are summarized in Table 1. It explains regarding 2 ranges of temperature from low to high. Table 1: Changes in curves and the phenomena which likely to occur. Temperature

DTA

TG

Phenomena Bond breaking and

218oC-392oC

Endothermic peak

Weight loss

evaporation in minor extent Bond breaking and

392oC-516oC

Endothermic peak

4.8.2 Biodiesel from Rubber seed oil:

Weight loss

evaporation in large scale


Figures 2 show the TGA results for Biodiesel produced from Rubber seed oil over a wide temperature range (30-600째C). DTA curve shows endothermic peak in the around of 55oC and in the around of 304oC. Initial endothermic peak might signify the presence of low boiling compounds likely to be remaining methanol used in transesterification reaction. The sharp peak for endothermic reaction might signify the overall bond breaking relevant to mass loss reaching its maxima at 304.5 째C TG curve shows weight loss starts after 200oC and in significant rate after 302oC. Maximum weight loss occurs almost 95% in the boiling range of 264 oC to 314oC. the first drop may lie somewhat near 88oC. The characteristic curve for TG shows the homogeneous composition of methyl esters in biodiesel specimen. From the results, the change which may happen in each temperature range and phenomenon which may occur are summarized in Table 1. It explains regarding 2 ranges of temperature from low to high. Table 2: Changes in curves and the phenomena which likely to occur. Temperature

DTA

TG

Phenomena Bond breaking and

150oC-450oC

Endothermic peak

Weight loss

evaporation in large scale

CONCLUSIONS The unrefined rubber seed oil is chosen as a potential non-edible vegetable oil for the production of biodiesel. The objective of this study is to investigate the use of biodiesel. Therefore, to accomplish this objective, the experiments were carried out.


Alkaline-catalyzed esterification process could not produce biodiesel from high FFA oils like the rubber seed oil. Therefore three-step esterification process converts the crude rubber seed oil with high FFA % to a more suitable form of fuel for diesel engines. The properties of rubber seed based biodiesel were found close to those of diesel fuel. Hence, the methyl esters of rubber seed oil can be a prospective fuel or performance improving additive in compression ignition engines. Various blends of biodiesel, neat biodiesel and diesel fuel are tested in compression ignition engines and its performance emission characteristics are analyzed. The main observations are:1. The diesel engine performed satisfactorily on biodiesel fuel without any significant engine hardware modification. 2. The lower concentrations of biodiesel blends found to improve the thermal efficiency. 3. Higher the concentration of biodiesel blend, higher is the reduction of smell and smoke density in exhaust gas. 4. Engine performance with biodiesel does not differ greatly from that of diesel fuel.

5. A little power loss, combined with an increase in fuel consumption, was experienced with the biodiesel. This is due to the lower calorific value of the biodiesel. But, in view of the petroleum fuel shortage, biodiesel can certainly be considered as a potential candidate.

6. Therefore, by deducing the results of all experiments, it can be said that methyl esters of rubber seed oil can be successfully used in existing diesel engines without any modification.


References:

1. International Energy Outlook 2007 published by the Energy Information Administration, International Energy Outlook 2007 by Energy Information Adminstration, Office of Integrated Analysis and Forecasting, U.S. Department of Energy, Washington, DC 20585. (5.2007) 2. Energy & Power, Bangladesh. 3. IPCC Fourth Assessment Report: Climate Change 2007 by Intergovernmental Panel on Climate Change (IPCC). (2.2007) 4. Fangrui Ma, Milford A. Bio-diesel production—review. Bioresour Technol 1999. 5. Canakci M, Van GJ. Biodiesel production from oils and fats with high free fatty acids. Trans ASAE 2001;44. 6. Ramadhas AS, Jayaraj S, Muraleedharan C. Use of vegetable oils as I.C. engine 7. “Food and feed from legumes and oil seeds”, Chapman & Hall Publishing, Britain.Nwokolo, E. and Smat, J. 1996. 8. “Serum and liver lipids of rats fed rubber seed oil”, Plant Foods for Human Nutrition 38,Nwokolo, E. Kitts, D.D. and Kanhai, J. 1988. pp. 145-153 9. “Rubber seed oil quality assessment and authentication, Nigeria”, Journal of American Oil Chemical Society 82, pp. 465-469.Aigbodion, A. I., and I. O., Bakare, 2005. 10. “Preparation, analysis and applications of rubber seed oil and its derivatives in surface coatings”, Progress in organic coating; Aigbodion, A.I. and C.K.S., Pillai, 2000. 38, pp. 187-192.


11. Nutritional and toxicological evaluation of rubber seed oil. Journal of American Oil Chemical Society Gandhi, V.M. Cheriank, M. and Mulky, M.J. 1990, 67, pp. 883-886. 12. Biodiesel production: a review,Fangrui Maa, Milford A. Hannab,* a Department of Food Science and Technology, University of Nebraska, Lincoln, NE, USA. b. Industrial Agricultural Products Center, University of Nebraska, 211 L.W. Chase Hall, Lincoln, NE 68583-0730, USA 13. Preparation and properties of diesel fuels from vegetable oils; Schwab, A.W., Bagby, M.O., Freedman, B., 1987. Fuel 66, 1372±1378. 14. Biodiesel Production Technology August 2002–January 2004; J. Van Gerpen, B. Shanks, and R. Pruszko, Iowa State University, D. Clements, Renewable Products Development Laboratory, G. Knothe, USDA/NCAUR. 15. Prospects and potential of fatty acid methyl esters of some non-traditional seed oils for use as biodiesel in India. By M. Mohibbe Azam, Amtul Waris, N.M. Nahar Central Arid Zone Research Institute, Jodhpur 342003, India 16. BANGLADESH FOREST INDUSTRIES DEVELOPMENT CORPORATION (BFIDC).

17. Effect of blends of Rubber seed oil on engine performance and Emissions. By Prashant Gilla, S.K Soni b, K.Kundu c,Shankaransh Srivastavad, a Department of Mechanical

Engineering,

PEC

University

of

Technology,

Chandigarh

160012,Punjab,India, 18. TGA Analysis of Rubber Seed Kernel; Noorfidza Yub Harun,Faculty of Forestry and Environmental Management Fredericton, E3B 5A3, Canada,M.T. Afzal mafzal@unb.caAssociate Professor Faculty of Forestry and Environmental Management University of New Brunswick Fredericton, E3B 5A3, Canada. 19. Synthesis of Biodiesel via Acid Catalysis; Edgar Lotero, Yijun Liu, Dora E. Lopez, Kaewta Suwannakarn, David A. Bruce, and James G. Goodwin, Jr.*


Department of Chemical Engineering, Clemson University, Clemson, South Carolina 29634-0909

20. Physical, Mechanical Properties and Oil Content of Selected Indigenous Seeds Available for Biodiesel Production in Bangladesh; M.A. Haque, M. P. Islam, M.D. Hussain, F. Khan, Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.

21. Chamois leather tanning using rubber seed oil; Ono suparno, ika a. Kartika and Department of Agroindustrial Technology, Faculty of Agricultural Engineering, Indonesia. 22. Measurement of Lipase Activity in Rubber (Hevea brasiliensis) Seed; O.U. Njoku*, I.C. Ononogbu, and F.U. Eneh, Lipid and Lipoprotein Research Unit, Department of Biochemistry, University of Nigeria, Nsukka, Enugu State, Nigeria 23. Physicochemical Characteristics of Malaysian Rubber (Hevea Brasiliensis) Seed Oil; Bashar Mudhaffar Abdullah, School of Chemical Sciences & Food Technology, Faculty of Science and Technology, Universiti Kebangsaan, Malaysia, 43600 Bangi, Selangor, Malaysia, Jumat Salimon, School of Chemical Sciences & Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia.

24. Production of biodiesel from rubber seed oil by Acid-esterification and Alkalinetranesterification method; Prachasanti Thaiyasuit, Kulachate Pianthong, Pisit Techarungoaisan, Chawalit Thinvongpitak, Ittipol Vorapan, Department of Mechanical Engineering, Faculty of Engineering, Ubon Ratchathani University 34190.


25. Biodiesel production from crude rice bran oil and properties as fuel; Lin Lin a,*, Dong Ying a, Sumpun Chaitep b, Saritporn Vittayapadung a, a. School of Food and Bioengineering, Jiangsu University, Zhen Jiang 212013, China, b. Mechanical Engineering Department, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200, Thailand

26. Potential use of Malaysian rubber (Hevea brasiliensis) seed as food, feed and biofuel; aEka, H. D., a,*Tajul Aris, Y. and bWan Nadiah, W. A. a. Food Technology Division, School of Industrial Technology, b. Bioprocess Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang, Malaysia.

27. Toxicity study of of Malaysian Rubber (Hevea brasiliensis) Seed oil as Rats and Shrimps tests; Bashar Mudhaffar Abdullah, School of Chemical Sciences & Food Technology, Faculty of Science and Technology, Universiti Kebangsaan, Malaysia, 43600 Bangi, Selangor, Malaysia.

28. Biodiesel Fuel Production from Algae as Renewable Energy; A.B.M. Sharif Hossain, Aishah Salleh, Amru Nasrulhaq Boyce, Partha chowdhury and Mohd Naqiuddin, Biotecnology Laboratory, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia

29. Comparison of nitro-polycyclic aromatic hydrocarbon levels in conventional diesel and alternative diesel fuels; Crystal D. Havey1, R. Robert Hayes2, Robert L. Mccormick3, and Kent J. Voorhees11Colorado School of Mines, Department of Chemistry and Geochemistry, 1500 Illinois St, Golden, CO 804012 Renewable Fuels and Lubricants Research Laboratory, National Renewable Energy Laboratory, 1980 31st St., Denver, CO 80216, 3Center for Transportation


Technologies and Systems, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO. 80401

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A Study on the Production of Biodiesel from Rubber Seed Oil (Hevea Brasiliensis)  

A Study on the Production of Biodiesel from Rubber Seed Oil (Hevea Brasiliensis)  

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