Experimental studies and mass-transfer analysis of the hydrolysis of olive oil in a biphasic zeolite-membrane reactor using chemically immobilized lipase

Chemically modified zeolite-clay composite membranes have been used for the immobilization of porcine lipase using glutaraldehyde to provide a chemical linkage between the enzyme and the membrane. The lipase-immobilized membrane has been used in a biphasic enzyme membrane reactor (EMR) for the hydrolysis of olive oil, and the performance of the EME, has been evaluated in terms of the apparent volumetric reaction rate based on the volume of the aqueous phase used for the extraction of the fatty acids. The reactor system behaves as though it involved an irreversible reaction with negligible product inhibition. The effects of various operating parameters (pH, solvent, olive oil concentration, and temperature) on the performance of the EMR were evaluated. A model that divides the system into two regions, charged pores and an unstirred film adjacent to the pores, describes the mass transfer on the aqueous side of the reaction sites located at the pore mouth. The process involves the transport of Na+, OH-, and RCOO- ions where the film is considered as an electroneutral region while the space-charge model is used to describe transport inside the charged pores. The solution scheme requires the ion concentration and its gradient only at the pore end, and using the experimental data, the pore-wall potential was determined to be about -0.5 mV.