Biolubricant synthesis from waste cooking oil via enzymatic hydrolysis followed by chemical esterification

TLDR: In this paper, a two-step process of C. rugosa lipase-mediated hydrolysis of WCO to free fatty acids (FFA) followed by Amberlyst 15H esterification of FFA with octanol was developed.

Abstract: BACKGROUND Lubricants manufactured conventionally from non-renewable mineral oil resources are not biodegradable and are liable to cause adverse environmental impacts. Biodegradable vegetable oils present a promising lubricant feedstock alternative. Waste cooking oil (WCO), which otherwise finds no immediate potential utilization can be successfully used to synthesize bio-lubricant. A novel synthetic method was developed by using the two-step process of C. rugosa lipase-mediated hydrolysis of WCO to free fatty acids (FFA) followed by Amberlyst 15H esterification of FFA with octanol. The octyl esters produced was the desired biolubricant. RESULTS The effect of different physico-chemical parameters like temperature, catalyst loading, agitation speed, molar ratio of octanol:FFA and the presence of different desiccants on the esterification reaction was examined. The optimum conditions to get maximum yield of biolubricant in minimum time were, octanol:FFA molar ratio = 3:1, temperature = 80 °C, catalyst = 2 g and desiccant (preferably silica gel powder) = 50% weight of FFA. Fourier transform infrared spectroscopy confirmed that the product formed was ester. CONCLUSION Biolubricant (octyl esters) was prepared efficiently from WCO by the two-step process developed. This novel approach represents a viable means of producing lubricants from wastes which are renewable in nature and can be an alternative to non-renewable mineral oil feedstocks. Copyright © 2012 Society of Chemical Industry