Modeling of the Mass Transfer Effect in Biphasic Enzyme Membrane Reactor for Hydrolysis of Olive Oil

摘要

This article presents a model to explain the mass transfer phenomenon of the ions (OH-, Na+nand RCOO-) formed during the hydrolysis reaction on the aqueous side of the reaction sites in thenbiphasic enzyme membrane reactor (EMR) using lipase immobilized on modified poly (methylnmethacrylate-ethylene glycol dimethacrylate) (PMMA-EGDM) clay composite membrane. Ournmodel divides the aqueous side of the system into two regions, an unstirred film (aqueous side)nadjacent to the pore end (region I) and charged capillaries of the membrane (region II). The processninvolves transport of Na+, OH- and RCOO- ions in region I whereas the film is considerednas an electro-neutral region. Space charge model (consisting of Nernst-Planck equation for ionntransport and nonlinear Poisson-Boltzmann (PB) equation for charge distribution) is used to describentransport of ions inside charged capillaries (pores) in region II. The solution of the nonlinearnPB equation is computationally intensive and to overcome this difficulty, a series solution of thenPB equation for the charge distribution inside the capillaries is developed. The suggested solutionnis used to determine the rate of formation of oleic acid using the information on pore size of thenmembrane (determined from molecular weight cut-off experiment) and diffusivity data from thenliterature. The result shows that the concentration of RCOO- ions at the boundary of region I of thenaqueous phase increases with increasing the duration of reaction. The pore wall charge determinednusing the model is found to be in the range of 0.715-0.735 mV.