Qualitative analysis of biodiesel produced by alkali catalyzed transesterification of waste cooking oil using different alcohols

Abstract

The present study evaluates the nature of fatty acid methyl esters (FAMEs) formed through alkali-catalyzed transesterification of waste cooking oil (WCO) using methanol, ethanol as well as in combination, where the sequential addition of ethanol followed by methanol is done keeping the molar ratio of alcohol to oil constant (5:1), with sodium hydroxide as catalyst. A substantial reduction in reaction time from 8 h to 20 min is seen in the latter case. Further, the gas chromatography/mass spectrometry (GC-MS) analysis of the transesterified oil show a significant presence of FAMEs. Transesterified oil obtained from a combination of both the solvents show substantial quantities of unsaturated FAMEs [linoleic acids (41.89%), palmitelaidic acid (7.97%)], saturated FAMEs [stearic acids (4.62%), arachidic acids (2.54%)]and minor fraction of other acids. Hence, the utilization of WCO with the use of combined solvent system for transesterification, appear to have a great potential for replacing the conventional substrates that are being used for biodiesel production without much compromising on engine modifications.