Journal of Advanced & Applied Sciences (JAAS) Volume 03, Issue 03, Pages 84-88, 2015 ISSN: 2289-6260 Optimization of Biodiesel production parameters (Pongamia pinnata oil) by transesterification process P. Venkateswara Rao, S. Ramesh Mechanical Engineering, Kakatiya Institute of Technology & Science, Warangal- 506015, Telangana State, India. * Corresponding author. Tel.: +91-9989985728; E-mail address: pvrao.kits@gmail.com A b s t r a c t Keywords: Pongamia pinnata, non-edible oil, base catalyst, transesterification process, biodiesel, Optimization. Accepted:13 May2015 In this paper, investigations were made to optimize the yield of biodiesel from Pongamia pinnata crude oil (non-edible oil) by transesterification process. The biodiesel was prepared from crude oil by adding methanol in the presence of NaOH as catalyst. Catalyst is used to improve the reaction rate and yield of biodiesel, for this purpose NaOH is found to be a better catalyst than KOH in terms of yield. In transesterification reaction, a larger amount of methanol is to be used to shift the reaction equilibrium to the right side and produce more methyl esters. Several aspects including the type and quantity of catalyst (alkaline, acid, or enzyme), alcohol/vegetable oil molar ratio, temperature, purity of the reactants in terms of water content and free fatty acid content have an influence in the transesterification process. A maximum conversion of 94% (from crude oil to ester) was achieved using a 1:6 molar ratio of oil to methanol at 63 to 64 0 C in two hours with 6.5grams of NaOH per liter of oil and the formed biodiesel was tested for important properties and compared with ASTM standard results. Academic Research Online Publisher. All rights reserved. 1. Introduction Biodiesel is gaining popularity as a renewable, nontoxic, biodegradable and alternative to conventional fossil fuels. Biodiesel contains almost no sulphur, aromatics but contains about 10% of oxygen which is useful for combustion. Biodiesel can be used in all conventional diesel engines with no modification in pure form (B100) or may be blended with diesel at different concentration. Biodiesel is a methyl or ethyl ester of fatty acid made from renewable resources such as oils (edible / non-edible), recycled waste vegetable oil and animal fats [1]. The vegetable oils for automotive applications have acceptable cetane number (35-45), high viscosity, pour and flash point, appreciable heating values and low sulphur content [2]. The studies show that any oil can be used in its neat form but not preferable due to high viscosity. This major problem leads to poor atomization of the fuel. Reduction in viscosity of oils can be achieved by transesterification process and thus edible or nonedible oils converted into methyl ester of oil are called Biodiesel [3]. In Indian conditions non edible oils can be the most viable alternative for petroleum fuels since there is shortage of edible oils to meet the domestic requirements [4, 5]. These non-edible oil seed plants can be grown in waste and non-fertile lands. Non edible oil seeds can be obtained from jatropha curcus, pongamia pinnata, undi, saemaruba and moha. There are more than 300 species of trees, which produce non edible oil in India. The oil from these seeds can also be used for lightning purpose at night. The use of this oil in the engine directly reduces the production cost of biodiesel. The processed vegetable oil can also be used in the existing CI engine with no modifications (6-8). Bradshaw stated that 4.8:1 molar ratio of methanol to vegetable oil gives to 98% conversion into biodiesel, if the ratio is greater than 5.25:1, then gravity interferes with the separation of glycerol and the cost of production increases [9]. Freedman studied the effect
of molar ratio of methanol to oil which changes in concentrations of glycosides on the yield of methyl ester. Further in methanolysis of sunflower oil, the molar ratio is varied from 6:1 to 1:1 and concluded that 98% conversion to ester was obtained with the molar ratio of 6:1[10, 11]. Difference in biodiesel properties would lead to alter in injection, combustion, emission characteristics and performance of the engine. In this paper non-edible oil of Pongamia pinnata crude oil is selected for optimizing the process of biodiesel production. this oil is used for lighting lamps in rural areas. Pongamia seed oil has physical properties very similar to conventional diesel except high viscosity. Emission properties are cleaner for this oil as bio-fuel than for conventional diesel fuel. It has reduced toxic, smoke and soot emissions. 2. Materials and methods 2.1 Pongamia pinnata Among the many species available Pongamia pinnata is found to be one of the most suitable plants in India which can yield more oil to use as an alternative to diesel fuel. Pongamia tree is a medium sized that generally attains a height of about 8 meters and more than 50 cm of trunk diameter. The tree have a trunk generally short with thick branches spreading into a dense hemispherical in shape with dark green leaves [12]. This tree can tolerant to water logging, saline and alkaline soils and also withstand harsh climates as shown in Fig. 1(medium to high rainfall). Degraded lands, wastelands can be suitably used for this tree to grow. Fig. 2: Pongamia Tree with Fruits Fig. 3: Pongamia Seeds with Shell 85 P a g e Fig. 1: Pongamia Tree with Flowers Normally Pongamia Pinnata trees are planted along the road highways and the banks of canals to stop soil erosion. Seeds available under the trees along the road side are collected to get oil. At least 25% volume of thick yellow to brown oil can be extracted from seeds (Fig. 2, 3) by using a mechanical expeller. Normally 2.2 Biodiesel preparation Due to readily availability at low cost the Pongamia oil has become more popular as an alternative fuel. However, there are limitations to use this non-edible oil as fuel due to its high viscosity and poor combustion characteristics, which can cause improper atomization, fuel injector blockage and engine oil contamination. With the esterfication of oil better fuel properties can be obtained rather than using straight vegetable oil as a fuel [12]. In this study, the transesterification process is selected to make biodiesel from Pongamia oil. Raw oil
is filtered by using surgical cotton to eliminate water, solid particulate matter then heated to 105 0 C temperature and maintained at the same temperature for fifteen minutes to remove all the water content from oil. 3.1 Effect of catalyst The quantity of Catalyst plays an important role in the yield of methyl ester. The Fig. 5 indicates the yield of alkyl ester with quantity of catalyst. It is observed that the yield of ester increases as the catalyst quantity increases to certain extent, but it shows that after 6.5 grams usage of catalyst per liter of oil, the yield remains more or less constant. So it is better to use 6.5 grams of catalyst per liter of oil to obtain maximum amount of methyl ester. Fig. 4: Pongamia Biodiesel In base catalyzed treatment for each liter of oil, 200 ml of methanol (20% by volume) and 97% pure NaOH (Sodium Hydroxide) of 6.5 grams is added. The mixture is stirred until it forms a clear solution called Sodium Methoxide. This solution is added to the oil and stirred for fifteen minutes continuously to neutralization of sulphuric acid below 65 0 C temperature by stirring at 500 to 600 rpm in a closed container. When the solution turns into brown silky in colour, that shows the whole reaction is completed. After settlement of the mixture in decanter, bottom part of the glycerin is separated from the biodiesel. The formed Pongamia methyl oil ester (POME) is bubble washed with distilled water for about half an hour to remove soaps and un-reacted alcohol. Washing is repeated till the POME separated with clear water and formed biodiesel is heated to remove water as shown in Fig. 4 to be used in diesel engine [13, 14]. 3. Results and Discussion The factors strongly influence Transesterification process are molar ratio of alcohol, presence of water, catalyst, free fatty acids in oil samples, reaction temperature, reaction time and the agitation speed. Experiments were conducted to prepare biodiesel from Pongamia crude oil with NaOH as catalyst, at constant speed of agitation and by removing moisture. The results obtained are as follows: Fig. 5: Biodiesel yield with Catalyst 3.2 Effect of reaction time Fatty acid conversion into esters increases with reaction time. The reaction is slow at the beginning due to mixing and dispersion of alcohol with oil, but later the reaction proceeds very fast. The reaction time is varied from 0.5 to 3 hours and observed that yield is also improved as shown in Fig. 6. The yield of biodiesel increases with reaction time, but after 2 hours remains constant and found that 2 hours is the optimum time period for the transesterification process to complete reaction; hence the amount of yield is constant. 86 P a g e
3.4 Effect of Methanol The Fig. 8 shows that biodiesel yield is considerably influenced with the variation of methanol used for the reaction process. Theoretically 3 moles of methanol is required for 1 mole of raw oil to produce 3 moles of biodiesel and 1 mole of glycerine, but to obtain more biodiesel, excess amount alcohol must be used. The figure shows that a steady increase in the yield of ester up to 180 ml methanol per liter of oil and then remains almost constant even with excess amount of methanol. Fig. 6: Biodiesel yield with Time 3.3 Effect of reaction temperature The reaction temperature is another important factor that will affect the yield of biodiesel. Higher the temperature increases reaction rate and decreases the time required to complete the process due to the reduction in viscosity of oils. The yield of alkyl esters is found to be varying with variation in reaction temperature. It can be observed from Fig. 7, that the temperature variation from 50 0 C to 65 0 C yield of product increased. The maximum yield was obtained at 63-64 0 C, but after that reduced because loss of methanol due to evaporation beyond 65 0 C and above temperature. The conclusion is that the optimum temperature to obtain maximum yield is 63-64 0 C for Pongamia oil with methanol in the presence of NaOH as catalyst. Fig. 8: Biodiesel yield with excess Methanol 4. Conclusions Maximum quantity of methyl ester is obtained when 6.5 grams of Catalyst (NaOH) per liter of oil used. The optimum time period is found to be 2 hours for the transesterification process to complete. The optimum temperature to obtain maximum biodiesel yield is 63-64 0 C for Pongamia crude oil in presence of methanol. Maximum ester yield is obtained up to 180 ml of methanol per liter of oil and then almost remains constant even with excess amount of methanol. 5. References Fig. 7: Biodiesel yield with Temperature 87 P a g e [1] A Demirbas, Comparison of transesterification methods for production of biodiesel from vegetable oils and fats, Energy Conversion and Management, 2008; 49: 125-130. [2] C E Goering, A W Schwab, M J Daugherty, E H Pryde, A J Heakin, Fuel properties of Eleven Vegetable Oils, Transactions of the American Society
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