Recent progress of photocatalytic membrane reactors in water treatment and in synthesis of organic compounds. A review

Abstract

Hybrid processes combining membrane separation and heterogeneous photocatalysis represent an exciting technology because each technique complements the advantages and overcomes the challenges of the other. This combination gives plants set-up named Photocatalytic Membrane Reactors (PMRs). PMRs can be designed in two configurations: reactors in which the catalyst is suspended in the reaction mixture and reactors that utilize the photocatalyst immobilized/deposited on membrane surface, giving a photocatalytic membrane. PMRs allow to perform a variety of chemical reactions (e.g. degradation or synthesis of organic compounds) and separation in one step thus minimizing environmental and economic impacts in agreement with the Green Chemistry principles.Different PMR configurations (pressurized, submerged, with photocatalytic membrane, photocatalytic reactors with membrane distillation, with membrane dialysis, with a pervaporation membrane) have been applied in water treatment for degradation of different organic pollutants (such as dyes, pharmaceuticals and other pollutants) and in the synthesis of organic compounds (such as phenol, vanillin and phenylethanol). The main experimental results of the different applications will be described and critically examined in this review.