USE OF RESPONSE SURFACE METHODOLOGY (RSM) IN OPTIMISATION OF BIODIESEL PRODUCTION FROM COW TALLOW

Abstract

In this study, beef tallow, waste from slaughterhouses was used as a feedstock for the production of biodiesel due to its high yield capacity, availability, and low cost. Sodium hydroxide and methanol were used as catalyst and solvent respectively. Characterization of oil and biodiesel samples were carried out using the Association of analytical chemist (AOAC) and American society of testing and materials (ASTM) respectively. Other characterization methods used are Fourier transform infrared spectroscopy (FTIR) and gas chromatographymass spectrophotometry (GC-MS) techniques. FTIR was carried out to characterize (identify the constituent elements) of both the feedstocks and their methyl esters. The fatty acid profile of the raw feedstocks and the produced methyl esters were obtained using the gas chromatograph to ascertain the % concentration of the different fatty acids. The physicochemical properties of the oils and biodiesel were also determined and compared with standards. Optimization of the processes was carried out using response surface methodology (RSM) under the platform of Design Expert 7.0.0 which uses statistical regression models. The optimized yield from transesterification of cow tallow using RSM was 83.82%, obtained with optimum operating parameters of Temperature (54.3oC), Time (51.65 mins), Catalyst concentration (1.82 wt%), Methanol/oil ratio (4.08 mol/mol) and stirring speed (302 rpm). This work thus not only confirms cow tallow as a viable feedstock for the production of biodiesel but also proves that a high enough yield of cow tallow biodiesel can be obtained at feasible reaction conditions. This study concluded that the use of response surface methodology proves to be a viable optimization technique albeit with its limitations in the transesterification process.