Response surface optimization of biodiesel yield from pre-treated waste oil of rendered pork from a food processing industry

Abstract

In this study, the waste oil of rendered pork (WO-RP) from a food processing industry was studied as a source of biodiesel. The WO-RP was characterized and was found to have a high acid value of 4.30 mg KOH/g. A pre-treatment using H2SO4 was done through the standard titration method that resulted in a reduction of acid value to 0.75 mg KOH/g. The transesterification process over the KOH catalyst was carried out and optimized using the central composite design (CCD) using the Design Expert 7.0 software. The optimum conditions were found at 3:1 methanol–oil molar ratio, 0.55% catalyst loading, and 45-min reaction time. At optimum conditions, the biodiesel yield was 95.28 ± 0.15%. Its chemical characteristics were tested in terms of acid value at 0.75 mg KOH/g, ash content at 0.01 wt%, density at 0.86 g/cm3, HHV at 39.98 MJ/kg, water content at 0.10%, and kinematic viscosity at 6.9 mm2/s. The FAME profile shows the presence of linoleic, palmitic, oleic and stearic acid as major fatty acid components and functional group shows carbonyl group with traces of carboxylic at 1719 cm−1 and the sharp peak of esters at 1749 cm−1 indicating that the derived product is biodiesel.