Development of Bi-Functional Heterogeneous Catalyst for Transesterification of Waste Cooking Oil to Biodiesel: Optimization Studies

Biodiesel production waste cooking oil is usually limited by its high free fatty acid and moisture content. The synergetic effect of both base and acid source from biomass was employed to proffer way out to this challenge. This study shows the coupled development of sulfonated carbonized corn cob (S-CCC) and calcined cow-bone (C-CB) catalysts for transesterification of waste cooking oil. The catalyst was prepared by physically mixing several mass percentages of S-CCC and C-CB (fluorapatite) in strategic proportions. The maximum biodiesel yield of 96.2 % was attained for catalyst mixture of 60 wt% and 40 wt%. The developed catalyst mixture was characterized by Fourier Transform Infrared Ray (FTIR), powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Brunauer–Emmett-Teller (BET). The surface area (472.3 m2/g), pore size (2.4330 nm) and volume (0.1380 cc/g) were obtained for the catalyst. The XRD shows that the crystallized structure of the bifunctional catalyst was formed majorly between 2 theta 10 and 65.Also the SEM shows a well dispersive pattern of the particles of the catalyst. The developed catalyst was employed for biodiesel optimization studies by varying factors such as time, temperature, catalyst loading and methanol: oil using optimal design under the response surface methodology. Maximum yield of 98.98 % was attained at time 6 h, temperature 65 °C, catalyst loading 6 %wt/ wt of oil and methanol to oil ratio of 11.75:1. It was observed that time and temperature had notable effect on the biodiesel yield.