Waste Frying Oil Hydrolysis in a Reverse Micellar System

Abstract

In this work we explore the feasibility of using reverse micelles to carry out the enzymatic hydrolysis of waste frying oils (WFO). The effect of some relevant parameters, such as the water/surfactant molar ratio (W0), the oil volume fraction in the organic phase and the enzyme concentration was studied. As a preliminary result, we observed that the extent of the reverse micellar system was slightly higher in mixtures containing WFO than when prepared with virgin oil. The hydrolysis extent was found to strongly depend on the amount of water inside the micelles, and an optimum value of 13.3 was found for W0. Although the hydrolysis took place for every volume fraction of oil in the organic phase, the reaction conversion was limited at high oil fractions. A maximum hydrolysis extent was found at high enzyme concentrations, but the specific activity of the enzyme was much higher at low enzyme concentrations. An analysis of the products distribution showed that free fatty acids are the main hydrolysis products. These results provide an alternative route for the transformation of WFO into high added-value products, which could help to reduce the environmental impact of these wastes.