Application of Response Surface Methodology for Optimizing Methyl Ester (Biodiesel) Production from Cotton Seed Oil

Abstract

Bio fuels such as biodiesel and biogas were increasing attention all over the world as alternative for fossil fuels in automobiles. Transesterification is the process that is used for producing biodiesel which is accepted because of its efficiency. Transesterification is the process done for decreasing the viscosity of the vegetable oil. The reaction variables used were methanol/oil molar ratio (3:1-9:1), catalyst concentration (0.5-2%), temperature (40-70°C), and catalyst type. The biodiesel with best yield and quality was produced in case of cotton seed methyl ester, at 6:1 methanol/oil molar ratio and 1 wt% of catalyst (NaOH) the yield was 92.44% at 60 0 C temperature. The quality of the methyl ester produced is analysed by Gas Chromatography-Mass Spectroscopy (GC-MS) and Fourier Transform Infrared Spectroscopy (FTIR). FTIR and GC-MS analysis are studied to identify and confirm the presence of functional groups and fatty acid methyl esters. In this paper, we have used Transesterification of cottonseed oil to produce methyl ester using the catalyst H2SO4 and NaOH. This was optimized by using the box-behnken design approach of response surface methodology (RSM). The different parameters for the optimization of methyl ester production were investigated. Response surface Methodology is used for the optimization of parameters in Design Expert 12 software. The results attained from the experimental runs were modeled and analyzed by choosing a quadratic model. The results obtained from the analysis of variance (ANOVA) of the model developed for the percentage yield of methyl ester as a function of molar ratio, amount of catalyst and reaction time. The cost of production of one liter of methyl ester from cottonseed oil is slightly higher the cost of the diesel per liter.