Mn3O4 nanodots loaded g-C3N4 nanosheets for catalytic membrane degradation of organic contaminants.

Peroxymonosulfate (PMS) activation by heterogeneous catalysts has been widely investigated to remove organic contaminants. Nevertheless, the technology is restricted to the bench-scale batch system. For practical applications, a supported catalyst design based on a reactor configuration with catalyst recovery is the need for future development. In this study, Mn3O4 nanodots-g-C3N4 nanosheets (Mn3O4/CNNS) composites were prepared via a facile hydrothermal method. The micro-structures and compositions of composites were investigated by a series of characterization methods. It was found that the Mn3O4 nanodots (5-10 nm) were distributed uniformly over the CNNS. When the added amount of CNNS was 150 mg during the synthesis process, a composite named as Mn3O4/CNNS-150 was obtained, which exhibited the best performance on PMS activation for 4-chlorophenol (4-CP) removal. The Mn3O4/CNNS-150@PTFE membrane was synthesized by facile vacuum filtration. The catalytic membrane was applied in filtration experiments for the degradation of different contaminants. The stability tests revealed excellent stability of the catalytic membrane. The redox circles of Mn(IV)/Mn(III)/Mn(II) on the Mn3O4 surface were the main source of activated PMS and a possible activation mechanism in the reaction system was provided. This study is of great significance for the development of novel catalytic membranes with PMS activation.