Photocatalytic-membrane technology: a critical review for membrane fouling mitigation

The present paper provides an overview of the hybrid photocatalytic-membrane process and its new properties such as permeability, hydrophilicity, rejection, antifouling and photodegradation efficiency. The integration of photocatalysts and membranes could be occurred in three major steps firstly photocatalysts mixed matrix membranes, secondly photocatalysts immobilized on the surface of membranes, and thirdly membranes for the separation of photocatalysts from their suspensions. Different combinations of photocatalysts (TiO₂, CuO or ZnO) and membrane processes are presented and characterized in the review paper. Positive or negative effect of different configurations of photocatalysis and membrane processes are discussed on the antifouling and antibacterial properties of the membranes. This review outlines the coupling of photocatalysts with the membranes can reduce the fouling of the membranes due to three mechanisms: elevation of membrane hydrophilicity, induction of antibacterial properties and degradation of foulants by produced radicals. However, reactive radicals can destroy polymeric membranes. Moreover, a short introduction to the photoelectrocatalysts is presented combined with membrane processes.