Optimization of biodiesel production from spent cooking oil by fungal lipase using response surface methodology

Abstract

This study evaluated the potential of optimizing Spent Cooking Oil (SCO) transesterification for biodiesel production using Response Surface Methodology (RSM). Potential biodiesel yield from transesterification was optimized using a three-level four factor Response Surface Central Composite Design (RSCCD) with methanol oil ratio (1:1 to 3:1), temperature range 35-45 °C, agitation speed range 100-200 rpm and enzyme load 10-20%. Biodiesel properties including fatty acid methyl ester (FAME), Flash Point (FP), Pour Point (PP) and kinematic viscosity were compared with American (ASTM D6751) and European Union (EN 14214) standards. Biodiesel production was optimum at 3:1 methanol to oil ratio, temperature of 35 °C, agitation speed of 150 rpm and 20% enzyme load. 9 octadecanoic acid-hydroxyl methyl ester (33.83%) was the prominent FAME produced, while the viscosity (6 mm²/s), density (893 kg/m³), FP (260 °C) and PP (-0.5 °C) all met both American and European standards. This study showed that RSM is a viable methodology which could be used for optimization of biodiesel production from biological sources.

Keywords: Biodiesel; Spent cooking oil; FAME; Response Surface Methodology (RSM); Central Composite Design