Process optimization for biodiesel production from Moringa oleifera oil using conch shells as heterogeneous catalyst

Abstract

The potential of conch shells (CSs) as a suitable heterogeneous basic catalyst for transesterification of high FFA content non‐edible Moringa oleifera oil (MOO) was investigated. Biodiesel was produced by a two‐step transesterification process. In the first step, high FFA content of the oil was reduced from 40.25 to 1.4% using reaction conditions of 1:2 v/v methanol to oil ratio, 1.5 vol% H2SO4 concentration, 2 h reaction time and 60°C reaction temperature. In the second step, the esterified oil was converted into biodiesel by reacting with methanol using calcined conch shells (CCSs) as a heterogeneous basic catalyst. The physiochemical characteristics of the CCS catalyst were studied by X‐ray diffraction (XRD), scanning electron microscopy, and energy dispersive X‐ray (SEM–EDAX), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. The characterization results revealed that calcium oxide (CaO) was the major phase of CCS. The effect of process variables on biodiesel conversion was investigated by response surface methodology using Box–Behnken design and the independent variables taken for study are catalyst concentration, methanol to oil ratio and reaction time. The optimum process conditions were found to be 8.02 wt % catalyst concentration, 8.66:1 methanol to oil molar ratio and 130 min reaction time. Under these experimental conditions, methyl ester conversion of 97.06% was obtained which was in reasonable agreement with the predicted value. The structure of Moringa oleifera methyl ester (MOME) was characterized by FTIR and methyl ester conversion was determined by proton nuclear magnetic resonance (1H‐NMR) spectroscopy. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13015, 2019