Production of Methyl Ester from Used Cottonseed Oil Optimized Using Box Behnken Design Approach

Worldwide interest in biofuels, such as biodiesel and biogas as alternatives to fossil fuels, is growing. The transesterification method is usually applied in the production processes of biodiesel because of its numerous advantages. The viscosity of the oil sample was decreased by utilizing this technique. The production procedure of methyl ester is determined by the amount of free fatty acids (FFA) in the sample. The titration technique was employed to evaluate this for the crude cottonseed oil (CCSO) and used cottonseed oil (UCSO), with the following results: 0.56 % and 1.26 %. Heterogeneous alkali (calcined commercial CaO) catalyzed transesterification was used to convert UCSO into used cottonseed oil methyl ester (UCSOME). It involves the reaction of methanol with UCSO in the presence of the catalysts. Some of the reaction parameters that control the transesterification process were; the methanol-oil ratio, reaction temperature, reaction time, and catalyst concentration. The aforementioned parameters were optimized through the response surface approach; Box-Behnken Design (BBD). The response surface yield has been plotted graphically as part of the various parameters that improve biodiesel yield. An optimized UCSOME yield of 93.60 % was obtained at a 1:10 molar ratio, 2.5 wt.% catalyst concentration, 80-min reaction time, and 60 °C reaction temperature. 94.50 % was the experimental yield obtained based on these parameters, which shows that the response surface methodology is a successful technique for optimizing the yield. The purity of the methyl ester was determined using GC-MS and FTIR.