PORE STRUCTURE OF GEL CHITOSAN MEMBRANES .1. SOLUTE DIFFUSION MEASUREMENTS

The capillary pore model of water-swollen gels was used to interpret s olute diffusion through gel chitosan membranes. Diffusive permeability coefficients of 12 solutes ranging in molecular radius from 2.5 Angst rom (methanol) to 14 Angstrom (polyethylene glycol 4000) were measured for an untreated chitosan membrane, for four chitosan membranes cross linked with glutaraldehyde of concentrations between 0.01 and 1% and c oated with a protein and also, for comparison, for a commercial Cuprop han membrane. Through the capillary pore-model correlation of the abov e coefficients with the membrane water content, the following structur al factors of the examined membranes were calculated: pore radius, sur face porosity and tortuosity factor. Knowledge of these factors is req uired if the desired membranes are to be designed for a given applicat ion (e.g. dialysis).