Photocatalytic membrane for in situ enhanced removal of semi-volatile organic compounds in membrane distillation under visible light

Membrane distillation (MD) is emerging as a promising technology for wastewater reclamation to relieve the shortage of freshwater. However, due to the contamination of semi-volatile organic compounds (s-VOCs), part of s-VOCs would transfer the membrane and impact the permeate quality during the MD process. Herein, an innovative AgCl/MIL-100(Fe)/PTFE photocatalytic membrane (AM/PTFE) was rationally synthesized in view of the increasing s-VOCs rejection. The AM/PTFE membrane was applied in the photocatalytic direct contact membrane distillation (DCMD) system and nitrobenzene (NB) was selected as the model contamination for evaluating removal performance of s-VOCs under visible light. Compared with the MD process, NB removal rate increased from 63.44% to 87.84% in the photocatalytic MD system. Moreover, stable performance was maintained over five NB removal cycles experiment with s-VOCs rejection higher than 84.84% in the end. The enhanced rejection of s-VOCs could be attributed to the combination of adsorption and photocatalytic. The volatile NB molecules were adsorbed on the surface of photocatalytic membranes, and the photo-electrons (e-) generated by immobilized nanomaterials could effectively remove pollutants under visible light irradiation. This photocatalytic MD system provides an attractive avenue for the water reclamation from s-VOCs contaminated wastewater in the practical applications.