Optimisation of Biodiesel Production from Waste Margarine Oil Using Response Surface Methodology

This work presents biodiesel production using waste margarine oil and response surface methodology (RSM) for optimisation. The transesterification of waste margarine oil was carried out using sodium hydroxide (NaOH) as a catalyst under atmospheric pressure in a lab-scale batch reactor. Central composite design (CCD) was used to optimise four parameters: methanol-to-oil ratio (3–15 mol/mol), catalyst ratio (0.3–1.5 wt.%), reaction time (30–90 min), and reaction temperature (30–70 °C). Numeral optimisation was performed, and an optimum yield of 99.1% was obtained at an 11.906 methanol-to-oil mol ratio, 1.113 wt.% catalyst ratio, 59.646 min reaction time, 52.459 °C temperature, and a low percentage error yield of 0.942%. Analysis of variance (ANOVA) showed that the methanol-to-oil ratio had the highest influence on the biodiesel yield, followed by the catalyst ratio, and reaction time had the least impact after temperature. The kinetics study revealed that the reaction is controlled by a pseudo-first order, and the activation energy was found to be 62.41 kJ/mol. It was concluded that biodiesel could be produced using waste margarine oil as a cost-effective feedstock optimised by RSM.