Experimental investigation and process simulation of biolubricant production from waste cooking oil

Abstract

Waste cooking oil (WCO) or frying oil was used for synthesis of biolubricant via transesterification reaction. Biolubricant (dioleoyl ethylene glycol ester) was prepared from fatty acid methyl esters (FAMEs) of WCO with ethylene glycol (EG). The reaction was performed using calcium oxide (CaO) heterogeneous catalyst. Dioleoyl ethylene glycol ester is a potential biodegradable lubricant that could be used in industrial lubricant applications. The effect of changing operating conditions such as temperature, molar ratio of reactants, reaction time and catalyst loading was studied. The optimal conditions that achieved highest conversion were found to be 130 °C, 3.5: 1, 1.5 h and 1.2% (w/w) catalyst dosage. The produced biolubricant structure was tested using FTIR spectrum technique and its thermal stability was examined using TGA technique. The biolubricant properties were compared to two other biolubricants and also to specifications of four different ISO viscosity grade lubricants. It was found that produced biolubricant complies with ISO VG68 viscosity grade with better low temperature applicability. The process simulation was performed on Aspen HYSYS program version 9 using conversion reactor model and using Non-Random Two-Liquid (NRTL) activity coefficient model. Simulation results proved that the studied biolubricant production process is industrially applicable.