Analysis of linear macromolecule transport through aluminum anodic oxide membranes by pore model

An aluminum anodic oxide (AlAO) membrane consisting of highly regulated cylindrical pores of 20-30 nm pore radius was prepared to clarify the applicability of two transport models, the original pore (OP) model and the steric-hindrance pore (SHP) model, to the structural characterization of ultrafiltration (UF) membranes. Filtration and diffusion experiments were performed with the linear macromolecules dextran and polyethyleneglycol. The reflection coefficient (sigma) and solute permeability (P) were determined by analyzing rejection properties with the Spiegler-Kedem equation. In addition, the value of P was measured by diffusion experiments. Comparing the observed values with the theoretical predictions makes it clear that membrane structure can be quantitatively evaluated with the OP model by characterizing the size of the macromolecular solute by its radius of gyration (r(g)), but not by the Stokes-Einstein radius (r(s)).