Transesterification of Algae Oil and Little Amount of Waste Cooking Oil Blend at Low Temperature in the Presence of NaOH

Abstract

The present study describes the single-step transesterification method of biodiesel production from high free fatty acid (FFA) waste cooking oil blended with algae oil using a homogeneous base catalyst. Due to high FFA contents, two step transesterification is needed to convert oil into biodiesel and therefore the high FFA content of waste cooking oil is decreased by blending it with low FFA content algae oil, which would further lead only to single step transesterification of low FFA oil. The design and optimization studies were conducted using Response Surface Methodology (RSM). The box-Behnken design technique is applied to optimize the three process parameters, i.e., catalyst concentration (0–2 wt%), methanol concentration (v/v) (20–60%) and reaction time (60–180 min) at a uniform reaction temperature of 50 °C. The result of the current study indicates that an effective biodiesel yield of 92% can be obtained at the optimized condition of catalyst concentration of 1.5% (w/w), methanol/oil ratio of 21:1 and reaction time of 110 min at a constant reaction temperature of 50 °C. This analysis clearly shows that this study can resolve the storage problem of high FFA oils from different feedstock and RSM can be successfully used to model the reaction to maximize the biodiesel yield.