Effects of protein fouling on the apparent pore size distribution of sieving membranes

A characterisation method giving the average radius and the geometric standard deviation is used to study the influence of fouling on the apparent porous structure of ultrafiltration membranes. A way of estimating the pore density is proposed. Polysulphone membranes of different molar weight cut-offs and globular proteins of different size are used. It is shown how the effects of fouling on solvent flux and on retention depend on the size of both pores and foulant molecules. The results suggest that fouling involves two mechanisms: internal pore fouling and build-up of a layer depending on both porous structure and solute size.