Optimization of Nigerian Restaurant Waste Cooking Biodiesel Reaction Parameters using Response Surface Methodology

Optimization of Nigerian Restaurant Waste Cooking Biodiesel Reaction Parameters using Response Surface Methodology

M.A. Waheed (Department of Mechanical Engineering, Federal University of Agriculture, Abeokuta, Nigeria), O.D. Samuel (Department of Mechanical Engineering, Federal University of Petroleum Resources, Effurun, Nigeria), B.O. Bolaji (Department of Mechanical Engineering, Federal University Oye-Ekiti, Nigeria) and O.U. Dairo (Department of Agricultural Engineering, Federal University of Agriculture, Abeokuta, Nigeria)
Copyright: © 2014 |Pages: 13
DOI: 10.4018/ijeoe.2014100102


The present work deals with the production of biodiesel from Nigerian restaurant waste cooking oil (NRWCO) and the optimization of the parameters that influences the alkaline transesterification of NRWCO into biodiesel using response surface methodology. The optimization parameters like oil: oil/methanol molar ratio, catalyst amount and reaction time were done using Design Expert 6.06 software. It was found that the maximum yield of biodiesel was obtained in 79.8 min for 1: 5.9, oil: methanol ratio, 1.2 wt. % KOH amount. A total of 20 experiments using Central Composite Design were carried out. The R2, adjusted R2 and predicted R2 values were 0.982, 0.9657 and 0.9088 respectively show that the experimental values are in good agreement with the predicted values. The properties of biodiesel at the optimized parameters, thus, produced confirm to the ASTM, EN and BIS specifications, making it an ideal alternative fuel for diesel engine.
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The depletion of fossil fuels, increasing demands for diesel and uncertainty in their availability, depletion rate of energy source, emission of very dangerous pollutants, rapid industrialization and increasing price that make petroleum no longer economically sustainable have necessitated the search for cheap raw material cost. A sustainable and economical supply of raw material is the key factor for biodiesel to be competitive commercially (Fazal et al., 2011; Zeng et al., 2008; Su et al., 2009; Lei et al., 2010). Waste cooking oil presents a promising choice as an alternative feedstock for biodiesel production and to reduce production cost (Gnanaprakasam et al., 2013). In addition, the utilization of waste frying oils diminishes the problems of contamination, because the reusing of these waste greases can reduce the burden of the government in disposing of the waste, maintaining public sewers, and treating the oil wastewater (Encinar et al., 2007). Arora et al. (2012) reported that significant amount of organic waste from agriculture, industries, and community sources is collected annually; it can be convertible to useful energy forms like biohydrogen, biogas, bioalcohols, etc., through various Waste-To-Energy Routes (WTERs) for sustainable development. Urooj et al. (2013) remarked that usage of bio-energy is becoming more and more prominent due to the peak oil crisis.

The reaction is affected by several parameters such as the concentration of catalyst, oil to methanol ratio, reaction temperature, moisture, presence of free fatty acids (FFA) and agitation intensity (Encinar et al., 2005). This process involves many parameters that affect the reaction and optimizing so many reaction factors require large number of experiments, which is laborious, time consuming, and economically non-viable. Response surface methodology (RSM) is a useful statistical technique for the optimization of complex processes, as it reduces the number of experiments required to achieve ample data for a statistically pertinent result (Jeong & Park, 2009). Abhang and Hameeddullah (2012) hinted that optimization of process parameters is the key step in response surface methods to achieve high quality without cost inflation.

Yang et al. (2012) investigated the optimal production of biodiesel from waste deep frying oil by using different amount of catalyst and different amount of oil to methanol ratio. Seecharan et al. (2009) reported of their investigation on a laboratory scale production from used cooking oil in Trinidad and Tobago. Abdalla and Oshaik (2013) explained the concept of converting recycled oils to clean biodiesel. They further hinted that the use of waste cooking oil can go a long way in improving biodiesel economics. Conversion of waste frying oil into a valuable biodiesel after acid- pre treatments process is necessary in order to lower its FFA below 1% (Syam et al., 2013). Canakci and Van Gerpen (2001) developed a process by employing acid catalyst to pretreat the high FFA feedstocks until their FFA level was below 1%, allowing the subsequent use of alkaline catalysts to convert the triglycerides. Production of biodiesel from three mixtures of vegetable oil and used cooking oil by alkali-catalyzed transesterification was investigated and remarked that supplementary oil feedstock for biodiesel production can be recommended if engine performance tests provide satisfactory results (Nakpong & Wootthikanokkhan, 2009). Owolabi et al. (2011) reported that the properties of waste cooking biodiesel were not only comparable with that of others but also within standard limits. Utlu and Kocak (2008) concluded that frying oil methyl ester as alternative diesel engine fuel can be used successfully to operate a turbocharged direct injection diesel engine without modifications to engine or injection system. Phan and Phan (2008) reported that blend of 20 vol. % waste cooking biodiesel and 80 vol. % diesels (B20) could be applied in engines without major modification. Ketlogestswe and Gandure (2011) reported that performance of the engine when powered by biodiesel and its blends with petroleum diesel is very comparable to its performance when powered by 100% petroleum diesel.

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