Synthesis of biolubricant components from waste cooking oil using a biocatalytic route

Abstract

The call for “sustainable development” has laid special emphasis on the “go green” concept and thus countries worldwide are taking initiatives to procure successful “clean and green technologies”. In this milieu the uncongenial conventional mineral‐oil based lubricants, causing adverse environmental impacts, can efficaciously be replaced by biodegradable vegetable oil based biolubricants. This article presents successful utilization of waste cooking oil (WCO) to synthesize biolubricant using a biocatalytic route. The developed methodology includes a two‐step process of enzymatic (Candida rugosa) hydrolysis of WCO to free fatty acids (FFA), followed by biocatalytic (Novozyme 435) esterification of FFA with octanol in a solvent‐free system to produce the octyl esters (desired biolubricant components). A classical method of parametric study was employed to explore the effect of different physico‐chemical parameters on the esterification reaction. The reaction conditions to achieve maximum conversion (95%) in minimum time were, initial water content = 0.5 wt % of FFA, octanol: FFA molar ratio = 3:1, catalyst = 5 wt % of FFA and temperature = 60°C. Fourier Transform Infrared Spectroscopy confirmed that the product formed was ester. WCO thus serves as an alternative feedstock for biolubricant synthesis and additionally aids up in skillful waste minimization and reuse. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 933–940, 2014