Production of biodiesel from waste cooking oil under varying parametric conditions using hydrodynamic cavitation with a single holed orifice

Abstract

Biodiesel can be obtained by the trans-esterification of oils and alcohols in the presence of catalysts such as NaOH, KOH, etc. The triglycerides present in oil gets converted into fatty acid methyl ester (FAME) and glycerol. In this study, waste cooking oil and methanol are treated in a hydrodynamic cavitation reactor in the presence of NaOH for trans-esterification reaction to take place. The two layers obtained namely, Fatty Acid Methyl Ester layer and glycerol layer is separated using a separating funnel and the excess solvent (methanol) in the methyl ester layer is removed by evaporation. The usage of waste cooking oil can be considered most economical in contrast with fresh refined oils and hydrodynamic cavitation is also more efficient in comparison with the conventional methods. The process was carried under varying parameters such as methanol to oil ratio (4:1, 6:1, 8:1), catalyst loading (0.55%, 0.75%, 1%) and reaction temperature (40°C, 60°C, 80°C). The biodiesel content present in the samples was analysed using a High-performance Liquid Chromatography (HPLC) analyser. From the results obtained, the optimum condition for high biodiesel content was found to be at a molar ratio of 6:1, with a catalyst loading of 1%, at a reaction temperature of 60°C using Design-Expert software.