Further applications and developments were studied for the use of enzyme-facilitated liquid membranes (EFLM). The use of ethanol as a cosolvent in the aqueous phase of the EFLM enhanced the facilitated transport of phenyl-acetic acid by more than 13 times relative to the case where water with low butanol concentrations was used, and more than 1000-fold relative to non-facilitated transport in the butanol/water system. This transport enhancement is proposed to result from a favorable shift in the equilibrium between phenylacetic acid and its ester (ethyl phenylacetate) which is the species transported across the liquid membrane. The enhancement goes through a maximum with increasing ethanol content that is proposed to result from the observed denaturing of the enzyme at high ethanol concentrations. A simple model is proposed which qualitatively describes the observed enhancement by ethanol blends.