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 water-

reducible 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 compression-

ignition 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

Rapeseed

Canola oil (a modified

version of rapeseed)

Safflower oil

Sunflower seeds

Yellow mustard seed

Rubber seed oil

Algae [28]

Lard

Tallow

Poultry fat

Fish oil

Recycled

Restaurant

Cooking Oil

(Yellow Grease)

Rice bran oil[25]

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

Methyl ester

Formula Molecular weight Melting point

(ºC)

Palmitic acid

Methyl palmitate

C16H32O2

C17H34O2

256.428

270.457

63-64

30.5

Stearic acid

Methyl stearate

C18H36O2

C19H38O2

284.481

298.511

70

39

Oleic acid

Methyl oleate

C18H34O2

C19H36O2

282.465

296.495

16

-20

Linoleic acid

Methyl linoleate

C18H32O2

C19H34O2

280.450

294.479

-5

-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 Total area

Year started

(acres)1. Ramu Rubber Estate, Rumu, Cox's Bazar 2131.00 1961

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

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

01 BFIDC 32 635

02 Rubber garden (Private, standing committee) 32 550

03 Development board of Chittagong Hill Tract 12 000

04 Duncun Brothers 7 500

05 James Finley 5 000

06 Messrs. Ragib Ali 2 500

07 Ispahani Neptune 800

Total 92 985

2.6.2 Exploitation of rubber plant:

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 Diesel oil Rubber seed oil Biodiesel

Density (gm/cc3) 830 930 860

Specific gravity 0.830 0.930 0.860

Viscosity (cSt) 3.55 66 6

Flash point (0C) 55 198 72

Calorific

value(MJ/Kg)

43 37.5 35

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

Fatty acid composition (%) Rubber seed

oil

Palmitic (C16/0) 10.2

Stearic(C18/0) 8.7

Oleic(C18/1) 24.6

Linoleic(C18/2) 39.6

Linolenic(C18/3) 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 450-8500C. 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 SiO2 and Al2O3. [18] The chemical compositions of diesel

fractions were similar to fossil fuels.

2.7.4 Transesterification

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 °C 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 acid-

catalyzed 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 5000C

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 32.80C, respectively. After 1 h,

ester formation was identical for 60 and 45 OC runs and only slightly lower for the 32.80C

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, 1,4-

dioxane 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 “non-

flammable”. 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

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.

Fuel Property Diesel Biodiesel

Lower Heating Value, Btu/gal ~129,050 ~118,170

Kinematic Viscosity, at 400C 1.3-4.1 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% 0.05 max 0.05 max

Carbon, wt % 87 77

Hydrogen, wt % 13 12

Oxygen, by dif. Wt% 0 11

Sulfur, wt% 0.05max 0.0 to 0.0024

Boiling Point, 0C 180 to 340 315 to 350

Flash Point, 0C 60 to 80 100 to 170

Cloud Point, 0C -15 to 5 -3 to 12

Pour Point,0C -35 to -15 -15 to 10

Cetane Number 40-55 48-65

Lubricity SLBOCLE, grams 2000-5000 >7000

Lubricity HFRR, microns 300-600 <300

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 125°C compared to

petroleum diesel fuel, which has a flash point of 55°C.

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.

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.

Fig: 2.8 Glycerin

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

Regulated    

Total Unburned Hydrocarbons -93% -30%

Carbon Monoxide -50% -20%

Particulate Matter -30% -22%

Nox +13% +2%

Non-Regulated    

Sulfates -100% -20%*

PAH (Polycyclic Aromatic Hydrocarbons)** -80% -13%

nPAH (nitrated PAH’s)** -90% -50%***

Ozone potential of speciated HC -50% -10%

* 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, biodiesel’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 fuel’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:

Fig: 3.3 Flow chart for extraction of oil from Rubber seeds.

Rubber seed collection

Crushing by Expeller

Crude RS oil

Crude RS oil

Solvent extraction

Roasting for 10 minutes

Shell removal

Sun drying and sorting

Distillation to solvent recovery

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.

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

Fig: 3.4 Crude rubber seed oil

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 “The number of milligram of potassium hydroxide required

to neutralize the 1gm of oil or fat”. 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 + H2O) 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.

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

A.V =

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 640C,

agitation rate 400rpm and time 1 hr. After one hour of reaction, the

mixture was allowed to settle for 1 h and the methanol–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 °C) 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 °C

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.

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).

Biodiesel

Glycerin

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 MethodDensity at 150C IP-160/57Kinematic viscosity, 400C, cSt ASTM-D 445-65Kinematic viscosity, 1000C, cSt ASTM-D 445-65Pour point, 0C ASTM-D 97-57Flash point,0C ASTM-D 93-62Acid value, mg KOH/g IP-1/58Sulfur content, %mass ASTM-D 129-64Cetane no. ASTM-D 613-86Water content, % IP-74/57Carbon residue, % ASTM-D 189-65Ash content, % 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

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.

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.

Fig: 3.16 viscometer

Fig: 3.17 Color comparator

Flash point tester:

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.

Furnace:

Carbolite Furnaces, Bamford, England.

Maximum range 1100OC.

Control of temperature is quite manual

with highly refractory material built.

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: 3.19 Flash point testing machine

Fig: 3.20 Furnace

Fig: 3.18 Bomb calorimeter

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.

Fig: 3.21 TGA analyser.

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

weight

Solvent,

ml

Solvent

recovered,

ml

Oil

extracted

gm

Oil

volume

ml

Oil

content

wt. %

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

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.

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

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

Name of the

analysis

Method RSO

Solvent

extracted

Expeller

1

Expeller

2

Color ASTM & DIN

51900

3 2.5 4.5

Density at 150C,

g/cc

IP-160/57 0.9047 - 0.9319

Kinematic

viscosity,

cSt

400C ASTM-D 445-65 20.5933 - 44.7912

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

KOH/g

IP-1/58 56.8 24.45 5.49

Sulfur content, g/g ASTM-D 129-64 0.003062 - 0.02719

Cetane no. 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,

Kcal/kg

- 11253.652 - 9956.1534

* 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

(gm)

methanol

(gm)

catalyst

wt.%

Methanol

to oil molar

ratio

Product

(gm)

Yield%

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

0.5

4. 2.05 0.500 7.5:1 1.6364 79.82

* 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.

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

%

Yie

lds

Wt. of methanol

Table: 4.4 The effect of variation of oil to catalyst ratio on product yield.

Tube no.

RSO

(gm)

Catalyst

wt.%

Methanol

(gm)

Product

(gm)Yield%

1.

2.00

0.33

0.4

1.8204 91.02

2. 0.72 1.8933 94.67

3. 0.98 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

following graph.

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

Wt. of catalyst

%

Yie

lds

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

(wt. %)

product Yield Glycerin

gm wt. % gm wt. %

1.

25 5.00

0.1 No phase separation

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

8. 0.8 21.71 73.54 7.81 26.46

9. 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

* 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.

Fig: 4.4 Variation of catalyst concentration curve

%

Yie

lds

Wt of catalyst %

Glycerin

Biodiesel

Fig: 4.5 yield variation for change in catalyst %

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

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

(gm)

Catalyst

(wt. %)

Methanol

(wt. %)

Product

Yield

Glycerin

gm wt. % gm wt. %

1. 10 19.196 77.17 5.68 22.83

2. 15 19.470 78.38 5.37 21.62

3. 20 19.150 78.87 5.13 21.13

Fig: 4.6 yield variation for change in methanol

25 0.7

4. 25 19.598 77.50 6.72 22.59

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.

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

%

Yie

lds

Wt. of methanol

Glycerin

Biodiesel

c. Effect of variation reaction time on product yield.

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

(gm)

Catalyst

(wt. %)

Methanol

(wt. %)

Reaction

time

(min)

product Yield Glycerin

gm wt. % gm wt. %

1.

25 0.7 20

30 21.170 73.48 7.62 26.52

2. 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

Fig: 4.8 yield variation for change in time

* 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.

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%.

%

Yie

lds

Wt. of methanol

Glycerin

Biodiesel

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

(gm)

Biodiesel Yield Glycerin

gm wt. % gm wt. %

1.

0.7 20

200

191.61 77.78 54.71 22.22

2. 191.29 79.22 50.17 20.78

3. 195.10 78.55 53.28 21.45

4. 185.45 76.71 56.61 23.39

5.

150

143.99 75.95 45.59 24.05

6. 137.29 75.25 45.15 24.75

7. 141.14 75.54 45.69 24.46

8. 143.05 76.22 44.63 23.78

9. 140.24 75.56 45.37 24.44

10. 80 73.53 75.77 23.51 24.23

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

Kinematic viscosity, cSt

40 0C D 445-65 4.48 1..9-6 6.06

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,

D 664

0.052 0.80 max 0.34

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)

Emission gas

temperature (Oc)

Observation

9:1 8:37 80

Conventional

diesel

to

Biodiesel

Running smoothly,

No visible smoke,

Smell better with

increase of

biodiesel

percentage

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

RS biodiesel 100% 9:05 89

Conventional

diesel

100% 9:02 83

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

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

Biodiesel % in blend

Tim

e

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

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 × 4 mm

thickness) for analysis.

Table 4: The main wavelengths in the FTIR functional groups of RSO

Wavelength absorbed by RSO Functional group

Tem

pera

ture

Fig: 4. 8 yield variation for change in time

Biodiesel % in blend

3020 C-H stretching vibration (C is part of

C=C )

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 (>400°C), 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 (30-600°C).

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

218oC-392oC Endothermic peak Weight loss

Bond breaking and

evaporation in

minor extent

Bond breaking and

evaporation in large

392oC-516oC Endothermic peak Weight loss scale

4.8.2 Biodiesel from Rubber seed oil:

Figures 2 show the TGA results for Biodiesel produced from Rubber seed oil over a wide

temperature range (30-600°C).

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 °C

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

150oC-450oC Endothermic peak Weight loss

Bond breaking and

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:

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Mechanical Engineering, PEC University of Technology, Chandigarh

160012,Punjab,India,

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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.

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Department of Chemical Engineering, Clemson University, Clemson, South

Carolina 29634-0909

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M.D. Hussain, F. Khan, Department of Farm Power and Machinery, Bangladesh

Agricultural University, Mymensingh-2202, Bangladesh.

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Department of Biochemistry, University of Nigeria, Nsukka, Enugu State, Nigeria

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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 Alkaline-

tranesterification method; Prachasanti Thaiyasuit, Kulachate Pianthong, Pisit

Techarungoaisan, Chawalit Thinvongpitak, Ittipol Vorapan, Department of

Mechanical Engineering, Faculty of Engineering, Ubon Ratchathani University

34190.

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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

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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

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Technology, Faculty of Science and Technology, Universiti Kebangsaan,

Malaysia, 43600 Bangi, Selangor, Malaysia.

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Naqiuddin, Biotecnology Laboratory, Institute of Biological Sciences, Faculty of

Science, University of Malaya, Kuala Lumpur 50603, Malaysia

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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