Optimization of biodiesel production from waste frying oil over alumina supported chicken eggshell catalyst using experimental design tool

Anotace: An optimization of the biodiesel production from a waste frying oil via a heterogeneous transesterification was studied. This present study is also aimed at investigating the catalytic ehaviour of the alumina supported eggshell (ASE) for the synthesis of biodiesel. A synthesized ASE catalyst, at various mixing ratios of alumina to eggshell, was investigated and exhibited a better activity for the reaction when the eggshell and alumina were mixed via incipient wetness impregnation in 2 : 1 proportion on a mass basis and calcined at 900 °C for 4 h. The as-synthesized catalyst was characterized by basicity, BET, SEM, EDX, and FTIR. The 2k factorial experimental design was employed for an optimization of process variables, which include catalyst loading, reaction time, methanol/oil molar ratio and reaction temperature and their effects on the biodiesel yield were studied. The optimization results showed that the reaction time has the highest percentage contribution of 40.139% while the catalyst loading contributes the least to the biodiesel production, as low as 1.233 %. The analysis of variance (ANOVA) revealed a high correlation coefficient (R2 = 0.9492) and the interaction between the reaction time and reaction temperature contributes significantly to the biodiesel production process with percentage contribution of 14.001 %, compared to other interaction terms. The biodiesel yield of 77.56% was obtained under the optimized factor combination of 4.0 wt.% catalyst loading, 120 min reaction time, 12 : 1 methanol/oil molar ratio and reaction temperature of 65 °C. The reusability study showed that the ASE catalyst could be reused for up to four cycles and the biodiesel produced under optimum conditions conformed to the ASTM standard.