Modelling and optimization of transesterification of palm kernel oil catalysed by calcium oxide derived from hen eggshell wastes

Abstract

In this study, modelling and optimization of transesterification of palm kernel oil (PKO) catalysed by calcium o oxide (CaO) derived from hen eggshell wastes were investigated. The eggshells were calcined for 5 h at 900 ^o C. The catalyst derived from the eggshells after calcination was characterized by Fourier transform infrared (FTIR), scanning electron microscope (SEM) and X – ray fluorescence (XRF). The XRF results shows that the catalyst contains 98.16% of CaO. Variables for the transesterification of the PKO were optimized using response surface methodology (RSM) based on central composite design (CCD). The variables investigated were methanol to oil molar ratio, catalyst concentration, reaction temperature and time. A second order quadratic model (p < 0.0001) was developed for predicting the biodiesel yield. The model predicted maximum biodiesel yield of 96.395% under the following optimum process conditions: methanol to oil molar ratio of 9.02:1, o catalyst concentration of 3.106 wt.%, temperature of 51.4^oC and reaction time of 135.94 min. The value of the biodiesel yield predicted was close to the experimental value of 94.63%. Physicochemical properties of the biodiesel obtained were within the American Society for Testing and Materials (ASTM) standards for biodiesel. Hence, heterogeneous catalyst derived from eggshells wastes can be used for transesterification.

Keywords: Eggshells, Calcium Oxide, Transesterification, Optimization, PKO