A study on the stability of polyethersulfone ultrafiltration membranes in a photocatalytic membrane reactor

Abstract

To date no information about the stability of the polymer membranes in photocatalytic membrane reactors (PMRs) has been published. In order to implement this technology into the full scale the lifespan of the membranes should be assessed. In this paper the investigations on the influence of membrane properties, type of a TiO2 photocatalyst (P25, ST-01, A700, and A800), a presence of oxidative species and the process parameters such as feed cross flow velocity and transmembrane pressure (TMP) on the stability of commercial polyethersulfone ultrafiltration membranes with different cut-off in a PMR are presented. Under the conditions prevailing in the PMR all the tested membranes lost their separation properties towards dextrans. The membrane characterized by the finest pores and thus the most delicate skin layer was damaged to the highest extent. The small angular-shaped particles of ST-01 caused a more severe damage of the membrane surface than the large round-edge shaped particles of A800. The deterioration of the membrane separation properties was less severe at low (1bar) TMP value compared to that at TMP of 3bar. The loss of the separation properties of the membranes was caused to a greater extent by the abrasion of their surface by the photocatalyst particles than by the action of oxidative species.