Lipase Catalyzed Hydrolysis of Olive Oil in the Biphasic Enzyme Membrane Reactor: Modeling of Mass Transfer Effect

摘要

This article presents a model to explain the mass transfer phenomenon of the ions (OH~-, Na~+ and RCOO~-) formed during the hydrolysis reaction on the aqueous side of the reaction sites in the biphasic enzyme membrane reactor (EMR) using lipase immobilized on modified poly (methyl methacrylate-ethylene glycol dimethacrylate) (PMMA-EGDM) clay composite membrane. Our model divides the aqueous side of the system into two regions, an unstirred film (aqueous side) adjacent to the pore end (region I) and charged capillaries of the membrane (region II). The process involves transport of Na~+, OH~- and RCOO~- ions in region I whereas the film is considered as an electro-neutral region. Space charge model (consisting of Nernst-Planck equation for ion transport and nonlinear Poisson-Boltzmann (PB) equation for charge distribution) is used to describe transport of ions inside charged capillaries (pores) in region II. The solution of the nonlinear PB equation is computationally intensive and to overcome this difficulty, a series solution of the PB equation for the charge distribution inside the capillaries has been developed. The suggested solution has been used to determine the rate of formation of oleic acid using the information on pore size (determined from molecular weight cut-off experiment) and diffusivity data from the literature. The average pore wall charge using the model has been determined to be 0.735 mV.