Production of Biodiesel Fuel from Waste Soya bean Cooking Oil by Alkali Trans-esterification Process

Biodiesel is biodegradable, clean-burning, non-toxic, renewable, high-quality, and cheap diesel fuel made primarily from waste vegetable oil which can be used without any alterations in engine design. The paper is concerned with the extraction and quality evaluation of the biodiesel fuels synthesized from waste soya bean cooking oil. Waste soya bean cooking oil had high amount of free fatty acid. Thus, single step transesterification process with the aid of homogeneous catalyst as 1% potassium hydroxide were implemented in this experiment. Methanol was chosen as alcohol solvent. In the transesterification process, the triglycerides in waste cooking oil was reacted with a methanol to form esters and glycerol as byproduct. The biodiesel were extracted for different oil to methanol ratio as 1:2, 1:3 and 1:4. The highest biodiesel yield of 76% was obtained at 1:3 volumetric ratio for 60oC reaction temperature and 1250 rpm stirring speed. Results show that the optimal methyl ester yield of 90% occurred at methanol: oil volume ratio of 3:1. The product met the ASTM fuel standards for relative density, acid value, relative density, calorific value, flash point and kinematic viscosity. keywords: Biodiesel; waste cooking oil; Waste cooking oil; alkali transesterification.