限外ろ過，精密ろ過膜における物質移動現象解析

Abstract

This review paper focused on i) the mass transport phenomena governing the performance of both ultrafiltration and microfiltration devices and ii) the effects of the pore size distribution, protein adsorption, and protein deposition on the transport characteristics.The actual sieving coefficients (Sa) of polydisperse dextrans through clean asymmetric polyethersulfone ultrafiltration membranes of varying molecular weight cut-off were evaluated as a function of dextran molecular weight. The flux-dependence of Sa was then used to evaluate the relative contributions of diffusion and convection to the overall rate of dextran transport. These results were well described by membrane transport theory using an available hydrodynamic model with the effective solute to pore size ratio evaluated using a partitioning model for a random porous media.Theoretical calculations were performed to determine the effects of several different types of pore size distributions on the transport characteristics of ultrafiltration membranes. The above partitioning model was in good agreement with the calculated results for a membrane with a log-normal pore size distribution with a geometric standard deviation of around 2.0. Theoretical modeling of pore blockage and pore constriction associated with protein adsorption showed good qualitative agreement with the experimental data.Experimental data for the sieving characteristics and hydraulic permeability of protein deposits formed on the survace of microfiltration membranes indicated that these properties are a function of the transmembrane pressure (compressive pressure) and solution ionic environment (electrostatic repulsion between the charged protein molecules). These experimental and theoretical results provide important insights into the underlying physical phenomena governing solute transport through ultrafiltration and microfiltration membranes, with a rational basis for the characterization and improvement of these membrane processes.