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

Abstract

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.

Keywords: Catalytic membrane; Mn(3)O(4) nanodots; Peroxymonosulfate; g-C(3)N(4) nanosheets.