Experimental investigation of the production of biolubricant from waste frying oil

In this study, waste sunflower frying oil used in fish frying was used for the synthesis of biodiesel and biolubricant through a transesterification reaction. The reaction was carried out with homogeneous and heterogeneous catalysts selected as potassium hydroxide, magnesium hydroxide, calcium carbonate, dopamine and bentonite-chitosan-KOH. The parameters affecting the reaction were determined as temperature, time, amount of catalyst, and molar ratio of methanol/WSFO. The stirring speed was as a constant value of 600 rpm. The best conditions for getting the highest conversion rate were studied with KOH, CaCO3, and bentonite-chitosan-KOH catalysts at 65 °C for 120, 60, and 90 minutes, 5:1, 4:1, and 3:1 methanol oil ratio, and a 1% catalyst amount. KOH catalyst yielded 88.4% ester (FAME) from the obtained biodiesel. The biodiesel yield was low in the experiments with the other catalysts. In addition, biodiesel was analyzed for its heating value, density at 15 °C, viscosity at 40 °C, flash point, water, and cloud point. The structure of the produced biolubricant was tested using the FTIR, and its thermal stability was investigated using the TGA technique. The pour point, flash point, viscosity index, and viscosities of the biolubricant at 40 and 100°C were determined.