Preparation and decontamination performance of a flexible self-standing hydrogel photocatalytic membrane

Abstract

The membrane immobilization of photocatalyst is a kind of win-win mode which can not only avoid the loss of catalyst but also give the membrane antibacterial and self-cleaning properties. Nevertheless, the inefficiency and low durability remain two major obstacles to hinder its practical applications. Herein, a facile micro-solvent combustion synthesis (MSCS) and sodium alginate (SA) crosslinking method were proposed to fabricate an integrated and self-standing membrane of nano-ZnCeOx combined with porous graphitic carbon nitride (ZnCe@PCNM). In the photocatalytic-membrane separation system, the water flux of ZnCe@PCNM was 800 l m−2•h−1•bar−1. Remarkably, the separation efficiency of ZnCe@PCNM could reach more than 90% during the 4-h continuous membrane separation process. The water flux of ZnCe@PCNM under visible light decreased only 21% which was less than that in the absence of light (53%), and the original flux could be completely restored after photocatalysis, signifying that the prepared ZnCe@PCNM had good self-cleaning ability in membrane separation. Meanwhile, ZnCe@PCNM exhibited 99% removal efficiency and 0.06131 min−1 reaction rate in photocatalysis experiments under 1-h visible light. The removal efficiency of ZnCe@PCNM was 1.2-fold and 2.8-fold that of carbon nitride particles (CN) and hydrogel membrane morphology (CNM), respectively. The optical properties test of ZnCe@PCNM showed that its excellent photocatalytic activity was derived from the rapid electron transfer caused by cross-linked structure, heterojunction and the oxygen vacancies induced by nano-ZnCeOx. The radical quenching experiment and EPR experiment showed that •O2− and •OH both were the main factors in reaction.