Biodiesel is an excellent substitute for fossil diesel, which received a significant attention in recent decades. Catalyst methods are frequently used to produce biodiesel at low temperatures and pressures. The present work investigates the methanolysis of waste cooking oil with the acid value of 1.86 mg KOH/g employing a variety of homogeneous base catalysts, including KOH, NaOH, CH3OK and CH3ONa. Among the studied catalysts, CH3OK produced the highest biodiesel yield at 99.0%, followed by CH3ONa, KOH and NaOH under the identical reaction conditions. The reaction was carried out for 30 min at 600 ºC and a speed of 600 rpm with a molar ratio of 6:1 for methanol-to-waste cooking oil (WCO) and a 1 wt.% catalyst. However, the viscosity, flash point, density and acid value of the biodiesel all met ASTM criteria, indicating that biodiesel made from KOH, NaOH, CH3OK and CH3ONa is of high quality.

Consumption of fossil fuels has resulted in several economic and environmental consequences, prompting a quest for renewable energy sources rather than a reliance on fossil fuels. Biodiesel is a renewable source of energy that can be substituted for fossil fuel-based diesel fuel. Transesterification is the most economically viable way of producing biodiesel. However, the biodiesel manufacturing method based on transesterification has a disadvantage due to the immiscibility of the two key reactants, alcohol and oil, which results in a mass transfer resistance and reduces biodiesel yield. Several researchers have investigated using another solvent called a co-solvent to overcome the mass transfer barrier in the reaction medium. The purpose of this review was to examine the influence of several co-solvents on biodiesel synthesis that had been previously investigated the research

The aim of this study was to examine the production of biodiesel from waste cooking oil with an acid value of 1.82 mg KOH/g in the presence of methanol and KOH, utilizing cosolvent technology in order to increase biodiesel output by overcoming mass transfer resistance. This study examined the effect of four cosolvents (hexane, diethyl ether, toluene and acetone) on biodiesel yield under optimized reaction conditions, including cosolvent-to-oil weight ratio, reaction time and temperature. The polarity index of cosolvent was determined primarily on its biodiesel yield performance. Highest yield (98.46%) of biodiesel was obtained at 20 wt.% of acetone; 1:6 molar ratio (oil-to-methanol), 1 wt.% KOH at 40 ± 1 ºC for 10 min of reaction time at 600 rpm. The physico-chemical properties of biodiesel such as acid value, density, kinematic viscosity and flash point were evaluated and found to be within ASTM standards.