Characterization of gel-filled porous membranes using moment-based interpretation of transport measurements

In this paper, moment theory is applied to previously reported results from a collection of transport measurements performed with gel-filled porous membranes containing polyacrylamide gel with different polymer concentrations [V. Kapur, J.C. Charkoudian, S.B. Kessler, J.L. Anderson, Hydrodynamic permeability of hydrogels stabilized within porous membranes, Ind. Eng. Chem. Res. 35 (1996) 3179; V. Kapur, J.C. Charkoudian, J.L. Anderson, Transport of proteins through gel-filled porous membrane, J. Membr. Sci., 131 (1997) 143]. Results from measurements of the hydraulic permeability, glucose diffusion, and the diffusive and convective transport of two proteins, ribonuclease A (RNAse) and bovine serum albumin (BSA) were analyzed. This analysis yields information about the pore size distribution in the gel material without requiring any a priori assumptions about the nature of that distribution. The average pore area in each membrane was determined by combining results from the hydraulic permeability and glucose diffusion measurements. Characteristics of the cumulative pore size distribution were captured by including results from one of the protein transport measurements. Results show that the cumulative pore size distribution, when normalized using the average pore area, is generally independent of the polymer concentration in these gels. It is also demonstrated that moment analysis enables one to make reasonable predictions of the transport characteristics of these membranes, predictions that incorporate characteristics of the pore size distribution.