A COMPARATIVE STUDY OF BIODIESEL

A Comparative Study o f Biodiesel.

Aliyu, Adetutu Oluwakemi

A COMPARATIVE STUDY OF BIODIESEL PRODUCED FROM SOME VEGETABLE AND WASTE OILS IN KADUNA. Aliyu, Adetutu Oluwakemi Department of Chemistry Nigerian Defence Academy PMB 2109, Kaduna. Nigeria. Email: [email protected] Abstract Mango seed oil, used vegetable frying oil, orange seed oil, corn oil and soybean oil were converted into respective methyl esters known as biodiesels. They were prepared in the presence o f homogeneous alkaline catalyst. The physicochemical properties such as density, flash point, kinematic viscosity, cloud point, pour point, cetane number, fire point, acid value, p H and percent yield were determined and the value obtained compared with biodiesel standards (ASTM D6751, Enl4213, ANP 42, IS 15607, JASO M360, & SANS 1935). Biodiesels obtainedfrom mango seed oil, used vegetable frying oil, orange seed oil, corn oil and soybean oil methyl esters were o f good quality and could be used as dieselfuel. Keywords: Biodiesel, Tr msesterification, used vegetable frying o f, agricultural produce and methyl esters

INTRODUCTION There is an increasing quest for the use of an environmentally cleaner fuel as an alternative to the conventional fossil fuel. This is bone out o f the concern to forestall oil depletion, greenhouse effect and global warming. One promising source of energy that has remained tropical, is the use of renewable fuel (biodiesel, bio ethanol). The US Satndard Specification for Biodiesel (ASTM 6751) has defined, biodiesel as a fuel comprised of mono-alkyl - esters o f long chain fatty acids derived from vegetable oils or animal fats [1]. Vegetable oils are extracted from biological materials (plants). They are usually esters of glycol with different chain length and degree o f saturation. Molecules of oxygen areabound in vegetable oil [2]. Vegetable oils are non-toxic and biodegradable. They are produced from renewable source and contribute a minimal amount of net green house gases, such as oxides of carbon, nitrogen and sulphur to the atmosphere [3]. The generation o f energy from renewable sources has the added advantage o f minimising or reducing over dependence on imported fossil fuels [4]. However, the characteristic high viscosity and poor volatility limit its use as fuel in diesel engines. Research has shown that highly viscous vegetable oils deteriorate the atomization, evaporated and airfuel mixture formation characteristics, leading to improper combustion and higher smoke emission. In view of the fact that its high viscosity generates operational problems like difficulty in engine starting, unreliable ignition and deterioration in thermal efficiency, it becomes necessary to convert vegetable oils to biodiesel. This option reduces its viscosity [5]. Oil seed crops (like palm oil, sunflower) have been considered for biodiesel production because they provide a positive energy return compared with energy used to produce the fuel [6, 7]. The current raw materials for biodiesel production or mono alkyl ester are vegetable oil, animal fat and micro algal oil [7]. However, vegetable oil is being used as a sustainable commercial feedstock. O f the more than three hundred and fifty (350) identified oil bearing crops, only sunflower, soybean, cotton seed, rap seed, and peanut oils are considered as potential alternative fuels for diesel engines [8]. The higher cost of solid vegetable oil affects the production cost of biodiesel, [10]. Application of base catalyst may cause problem due to the side saponification reaction which creates soap and consumes catalyst in palm oil and sunflower [6]. Those 10



problems occur because of higher content of fatty acids and water in used cooking oil [11]. The main aim of this study is to compare the physicochemical properties of biodiesel produced from Vegatable oil from (com and soybean) and those from (mango seed, orange seed and used vegetable frying oil) oils with the internationally acceptable standards.

EXPERIMENTAL Material and methods Soybean and com seeds were purchased from station market, Kaduna South, Nigeria. The mango seeds and orange seeds were collected from Marafa Estate farm in Kaduna. The used vegetable frying oil was obtained from cadets’ mess atNigerian Defence Academy, Afaka, Kaduna. The used vegetable frying oil (UVO) was filtered to remove impurities under vacuum pump, pressure (160psi/11 bar). Sodium hydroxide, methanol (99.5 % purity and density o f 0.791 g/cm3), sodium sulphate, n-hexane were analytical reagents purchased from Aldrich Chemicals were used without further purification. Extraction of oil Ten(10)kg of mango seeds were collected from Marafa estate farm and dried at 80° C ± 5°C for 5 hours in a hot air oven. The dried seeds were shelled and milled. The oil was extracted from the milled mango seed with n-hexane at (40-60°C) using the Soxh let extraction method method [12]. The solvent was removed from the extract and the oil content was found to be 60 % by weight of the milled mango seed. About 4 litres of the oil was extracted and kept over anhydrous sodium sulphate for three days and filtered t h ough glass 57 wool to remove water and.f ;e particulate matter present in it. The filL;ed oil was then stored in glass bottles for further experiments. The same method was used for extraction of oils from com seeds, mango seed orange seeds and soybean (Indiana) respectively and the per cent yields were 55,60,60 and 90 % respectively. Biodiesel production In this study, the base catalyzed transesterification process was used to make biodiesel from mango seed oil. The reaction was carried out in a batch reactor. A portion, (500 cm3) o f mango seed oil was heated uo to 70°C with vigorous stirring in a round bottom flask to drive off moisture. A portion (2.5g) of catalyst NaOH was dissolved in methanol (99.5%, Sp.G 0.79 lg/cm3) in bi molar ratio, (as shown in equation 2 below in a separate vessel and transferred into the round bottom flsak containing the oil while stirring the mixture continuously. The mixture was maintained at 60 °C and atmosphere pressure for 60 minutes. The mixture was allowed to settle under gravity for 24 hours in a separatory funnel. The products formed during transesterification were mango seed oil methyl ester and glycerine, excess alcohol, catalyst, impurities and traces of unreacted oil. The upper layer consisted of biodiesel, alcohol and some soap. Mango seed oil methyl ester (biodiesel) was mixed, washed with hot distilled water to remove the unreacted alcohol, oil and catalyst and allowed to settle chemical property test. The same procedure was used for used vegetable oil, com seed oil, orange seed oil and soybean oil respectively [13].

Equation of reactions RCOOH + NaOH? RCOONa + H20 ...........................................i CH3OH + NaOH ? NaOCH3+ H20 ............................................ii

11



H2C— OOC— R1 H

OOC— R2 +3CH3OH

NaOH

o c - — R1

' CH 3- - o

o c - -R 2

CH?—- o o c - -R 3

H £ — 00C— R3 T riglyceride

CH3— - o

M ethanol

iC -

+

-O H

Fc - -O H F iC - -O H

Fatty acid m ethyl esters Glycerol

...3 Biodiesel Analysis Parameters have been analyzed by specific methods to verify whether the products fulfill the American Standard of Biodiesel Testing Methods (ASTM D 6751) and European Norm for Biodiesel (EN 14214). Viscosity was determined in mm2/S at 40° C using Houillon Viscometer (France) with ISL. Total acid value was measured using titration method. Cloud point was determined by ASTM D 97, fire point and cetane number were determined by standard methods. Density was determined by ASTM D 287 methods. Pour point was determined by ASTM D 97 method. Flash point and fire were determined by ASTM D 93 method[ 15]. Result and Discussio'3 The result obtained from the experiment are presented in Table 1,2 and 3 respectively. Table 1 shows the physicochemical parameter o f biodiesel obtainted from vegetable and waste oils, Table 2 shows the characteristics o f the biodiesel produced and Table 3 shows Physicochemical properties trend of biodiesels from vegetable and waste oils. The acids values of mango oil methyl ester, com oil methyl ester, used vegetable oil methyl ester, and soybean oil methyl ester are shown in Table 1. They range from 0.18 to 0.24 mg KOH/g oil which compares favourable with biodiesel standard (0.8mg KOH/g (max) ASTM D664). The acid value indicate the low amount o f free fatty acid on all types of methyl ester with the exception o f used vegetable oil methyl ester and orange seed oil methyl esters. The high acid value in used vegetable oil methyl ester and orange seed oil methyl ester are largely due to unsaturated bonds present in vegetable oils [14]. The percent yield o f the extracted oils range between (55 - 90)%. These value were higher than the value reported for jatropha and castor oil (52 - 56)% yield respectively except for com oil which is 55% which compares with castor oil [ 18,19]. The pH o f the extracted oils range between 6.2 6.7. These values fall within the acceptable range of (ASTM D4806) with the exception of soybean oil which is lower by 0.3 [ 1]. The viscosity values obtained at 40°C for the biodiesel ranged between (4.02 and 4.22)°C which falls within the acceptable range of ASTM D 6571 as shown in Table 2. A low viscosity index signifies relatively large change of viscosity with temperature. The maximum viscosity of biodiesel should be 4.1 units at 40°C. Viscosity of esters o f used vegetable oil methyl ester exceeded this limit significantly. While other alkyl esters o f com oil (Zea mays), mango oil, orange seed oil and soybean oil methyl ester are in agreement with the ASTM standards. The higher the viscosities, the poorer the atomization o f the fuel. Accordingly operation o f the injectors would be less efficient. Moreover, at decreasing temperature, viscosity o f biodiesel increase[15]. This high viscosity generates operational problems like difficulty in engine starting, unreliable ignition and deterioration in the thermal efficiency [5]. The cetane number (min) of the biodiesels obtained from the experiment varied between 54 and 58. The cetane number obtained from the biodiesels from the vegetable and waste oils are higher than the standards (ASTM D 613 ASTM D6890). 12

A Comparative Study o f Biodiesel.....


The cetane number of fuel reflects its ignition delay. The higher the cetane number, th shorter the ignition delays [16]. Therefore, high cetane number is desirable for engine fuel. Cetane numbers of biodiesel differ depending on the respective oil sources and from country to country. Cetane Numbers o f biodiesel from soybean oil ethyl esters lies between 45.8 and 56.9 [16]. Cetane numbers increase with increase in chain length, decrease with increase in the number of double bonds, and decrease as double bonds and carbonyl groups move towards the centre of the chain. Increasing cetane number of biodiesel has been shown to reduce nitrogen oxides emissions [16]. Cetane number signifies the ignition quality of fuel. High cetane number fuel will facilitate easy starting of compression ignition engines and lessen engine roughness. The pour point obtained from the biodiesels under investigation ranges between 3 and 11 °C. These compare favourably with standards (ASTM Ps 121) with the exception o f used vegetable oil methyl ester which is slightly higher than the standards. Biodiesels exhibit poor flow properties at low temperature. The structural properties of biodiesel that affect freezing point are degree of unsaturation, chain length and degree of branching. Pour point measures the lowest temperature at which the oil is observed to flow. It is important because this defines the lowest temperature at which the fuel can still flow, before it gels [17]. Flash points of the biodiesels generated from vegetable and waste oils range between 166 and 194 °C which is higher than the biodiesel standards (EN, ASTM D 6157). The flash point o f the biodiesels are generally higher than that of geo-diesel. It is higher than 90 °C, and is thus safer than geo-diesel from the standpoint of fire-hazards[ 15]. Fuels with flash point above 66 °C are considered as safe fuel. The cloud point for biodiesels generated from vegetable and waste oils ranges between (2 and 15) °C. The cloud points for mango oil, orange seed oil, com oil and soybean oil methyl esters are (7.0,5.0,4.0 and 2.0) °C respectively when compared to biodiesel standards o f (-3 to 12 ASTM PS 121), As it fell within standards and the fuel will perform satisfactorily even in cold climatic conditions. Flowever, used vegetable oil methyl ester has high cloud points (15 °C) which can affect the engine performance and emission adversely under cold climatic conditions[2]. The fire points for biodiesels under investigation ranges from 182 °C as in soybean oil methyl ester to 190 °C in orange seed oil methyl ester. The methyl esters fire points are low (182-214 °C) compared to that o f jatropha methyl ester (296 °C) [17]. Fire point is the lowest temperature at which a specimen will sustain burning for 5 seconds. This parameter has great importance while determining the fire hazard (temperature at which fuel will give off inflammable vapour) [18]. The density at 15 °C for biodiesels is the volume of any liquid at a given temperature. The densities for mango oil, orange seed oil, com oil, soybean oil and used vegetable oil methyl esters are (0.89, 0.87, 0.86, 0.86 and 0.88) kg/Lrespectively. These agree with biodiesel standards (ASTM D6751 and EN 14213). Higher density means more mass of fuel per unit volume for biodiesel oil. The higher mass of fuel would give higher energy available for work output per unit volume [12]. Comparison of the biodiesel The trend of viscosity of the biodiesel obtained from the vegetable and waste oils at 40 °C examined was:- corn oil methyl ester (COME), Mango seed oil methyl ester (MSOME), Soybean oil methyl ester (SBOME), Orange seed oil methyl ester (OSOME), Used vegetable oil methyl ester (UVOME). Table 3. Viscosity is a measure o f the internal fluid friction or resistance of oil to flow, which tends to oppose any dynamic change in the fluid motion. As the temperature of oil is increased its viscosity decreased and it is therefore able to flow more readily. The lower the viscosity of the oil, the easier it is to pump, atomize and achieve finer droplets [18]. Hence, it can be concluded that COME is best the in terms of viscosity when compared to others. 13



The trend o f PP (pour point) o f the biodiesel obtained from vegetable and waste oils under investigation revealed that SBOME, COME, OSOME, MSOME, UVOME (Table 3). Since pour point measures the lowest temperature at which the oil is observed to flow. It is important because this defines the lowest temperature at which the fuel can still be moved, before it gels [18]. in this regard, SBOME is regarded as the best in terms of the parameter considered. The trend o f FP (flash point) o f the biodiesel obtained from the vegetable and waste oils under investigation revealed that COME, SBOME, MSOME, OSOME, UVOME. The flash point temperature o f biodiesel fuel is the minimum temperature at which the fuel will ignite (flash) on application o f an ignition source. Flash point varies inversely with the fuel’s volatility. Minimum flash point temperatures are required for proper safety and handling o f diesel fuel [19]. In this regard, COME is regarded as the best in terms of the parameter considered. The trend o f CP of the biodiesel obtained from the vegetable and waste oils under investigation revealed that SBOME, COME, OSOME, MSOME, UVOME. Low cloud points enhance fuel performance even in cloud climatic conditions [2]. Hence, SBOME is regarded as the best in terms o f the parameter considered. The trend o f FiP (fire point) o f the biodiesel obtained from vegetable and waste oils under investigation revealed that SBOME, MSOME, COME, OSOME, UVOME. Since fire point is the lowest temperature at which a specimen will sustain burning for 5 seconds, this parameter has great importance for determining the fire hazard (temperature at which fuel will giveT ff inflammable vapour) [19]. Therefore, SBOME is regarded as the best. The trend in density o f the biodiesel obtained from the vegetable and waste oils under investigation revealed that SBOME, COME, OSOME, UVOME, MSOME. Density is another important property of biodiesel. It can be observed from the findings that MSOME has the highest value o f 0.89kg/L as compared to all samples. The SBOME has a minimum density vaiue of 0.86kg/L. Since higher density means more mass o f fuel per unit volume for biodiesel oil, the higher mass o f fuel would give higher energy available for work output per unit volume [2]. Therefore, MSOME could be considered the best in terms of the parameter considered. Conclusion In this study, the biodiesels produced under investigation compared favourably with the international biodiesel standards, therefore it can be inferred that SBOME (soy bean oil methyl ester) will give the best quality biodiesel within the quality test performed (i.e. SBOME has better quality than others in per cent yield, PP, CP, and FiP).

Acknowledgm ent I wish to acknowledge the effort of my research student cadet officer J Usman NDA/ 8517 for his untiring effort in ensuring that the research is successful. My special appreciation goes to Nigerian Defence Academy, Kaduna. Nigeria for allowing me the use o f the research laboratory and finally the painstaking editorial assistance o f Dr. Mrs. Taiye Gefu is deeply appreciated.

References 1. A.B.M.S. Hossain and A.M. Al-saif (2010) Biodiesel fuel production from soybean oil waste as agricultural bio-resource Australian Journal o f Crop Science 4 (7):538-542. 2. S. Anthony raja, D.S. Robinson Smart, and C. Lindon Robert Lee., (2011) Biodiesel production fromjatropah oil and its characterization Res. J. Chem. Sci. 1 (1); 81-87. 14



3. Bouaida A, Martineza M, Aracil J (2007) Long storage stability of biodiesel from vegetable and used frying oils. Fuel 86:2596-2602. 4. Blanco-Canqui H, Lai R (2007) Soil and crop response to harvesting com residue for biofuel production. Geoderma 141:355-362. 5. Paugazhabadivu, M, Jeyachandran K (2005) Investigation on the performance and exhaust emissions of a diesel engine using preheated waste frying oil as fuel. Renewable Energy 30:21892202 . 6. Hossain ABMS, Boyce AN (200a) Comparative study of biodiesel production from pure palm oil and waste palm oil .Arab G ulf Journal o f Scientific Research 27 (1&2): 33-38. 7. Kallivroussis L, Natsis A, Papadakis G (2002) The Energy Balance o f Sunflower Production for Biodiesel in Greece. BiosysEng 81:347-354. 8. Demirbas A, Kara H (2006) New options for conversion o f Vegetable Oils to Alternative Fuels. Energy Sources, Part A; Recovery, Utilization, and Environmental Effects 28:619-626. 9. Niotou, AA, Kantarellis EK, Theodoropoulos DC (2008) Sunflower shells utilization for energetic purpose in an integrated approach o f energy crops: Laboratory study pyrolysis and kinetics. Biores Tech 99:3174-81. 10. Hubera GW, O ’connorb P, Corma A (2007) Processing biomass in conventional oil refineries: Production of high quality diesel by hydro treating vegetable oils in heavy vacuum oil mixtures. Applied Catalysis A. General 329:120-129. 11. FIossianABMS, Boyce AN (2009b) Biodiesel production from waste sunflower cooking oil as an environmental recycling process and renewable energy. Bulgarian Journal o f Agriculture Science 15 (4):313-318. 12. H. Raheman and A.G. Phadatare, (2004) Diesel engine emissions and performance from blends of Karanja methyl ester and diesel. Biomass and Bio energy, 27,393-397. 13. Hass M.J., Scott K.M., Marmer W.N.and Folinga T.A., (2004) In Situ alkaline transesterification; an effective method for the production o f fatty acid esters from vegetable oils, J.A.M. oil chem., SOC 81-89. 14. Turkan, A, Kalay S (2006) monitoring lipase-catalyzedmethanolyses o f sunflower oil by reversedphase high performance liquid chromatography: Elucidation of themechanisms of lipases. J Chromat A 127:34-44. 15. A. K. Sarma, (2006) Biodiesel Production from Mesuaferrea L (Nahar) and Pongamiaglabra Vent (Koroch) Seed Oil, Ph.D. Thesis, Department of Energy, Tezpur University, India. 16. T. Ullman, R. Mason and D. Montalvo (1990) Study of cetane number and aromatic content effects on regulated Emission from a heavy-duty engine. Southwest Research Institute Report No. 08-2940, CRC contract Vel. 17. N. Chakraborty and-S C Sarka (2008) Development o f a biofuel lamp and its comparism with a kerosine lamp. Journal o f Energy in southern Africa 19(2):22-24. 15

A Comparative Study of Biodiesel.


18. Pranab K. Barua (2011) Biodiesel from seed o f Jatropha Found in Assam, India. International Journal o f Energy, Information and Communications. 2(1): 53-65. K. Sivaramakrishnan and P. Ravikumar (2012) Determination of cetane number o f biodiesel and its influence on physical properties. ARPN Journal of Engineering and Applied Science 7(2):205-201.

TABLE 1: Physicochemical properties of vegetable and waste oils O IL T Y P E S

% Y IE L D

pH

A C ID V A L U E S (m g K O E I/g

C o m o il

55

6 .6

0 .1 8

M a n g o O il

60

6.5

0 .1 9

U s e d v e g e ta b le oil

70

6 .7

0 .2 4

S o y a b e a n O il

90

6.2

0.21

O ra n g e o il

60

6.5

0 .2 2

6.5 - 9 .0 (A S T M D 4 8 0 6 )

0 .8 0 (A S T M D 6 6 4 )

V a lu e a c c o rd in g to s ta n d a r d m e th o d s

16

A Comparative Study o f Biodiesel....


TABLE 2: Physicochemical properties of biodiesels from vegetable and waste oils Oil Types

V is c o s ity

D e n s i ty a t

F la s h p o in t (°C )

Pour P o in t

F ir e P o in t

C e ta n e

C lo u d

(°C )

n o ( m in )

p o in t

a t 4 0 °C

15 °C

( m m 2 /S )

(K g/m 3 )

4 .0 6

0 .8 9

179

8 .0

184

5 6 .0

7 .0

4 .0 2

0 .8 6

166

5 .0

186

5 5 .0

4 .0

Used vegetable 4 .2 2

0 .8 8

194

1 1 .0

214

5 8 .0

1 5 .0

4 .0 8

0 .8 6

178

3 .0

182

5 4 .0

2 .0

Orange seed oil 4 .1 0

0 .8 7

180

6 .0

190

5 4 .0

5 .0

2 9 6 (JE S A )

5 1 .0 ( A S TM

-3 to

D 6 1 3 :A S TM

M

Mango seed

(°C )

(°C )

Oil methyl ester(MSOME) Com Oil methyl ester(COME)

oil methyl ester(UVOME) Soyabean oil methyl ester(SBOME)

methyl ester(OSOME) Values

1 .9 -6 .0

according to standard

(A S T M 6571)

methods

-1 5 to 0.8-0.89(ASTM 1 2 0 (E N 1 4 2 1 4 V 1 0 (A S T M 1 3 0 (A S T PS121)

D1298

M D 6751)

1 2 (A S T P S 121)

D 6890

TABLE 3: Physicochemical properties trend of biodiesels from vegetable and waste oils Physicochemical

Characteristic trend

Properties Viscosity@40 °C

COMEDMSOME □ SBOME □ OSOMED UVOME

Cetane number

SBOME =OSOME