Selectively efficient removal of micropollutants by N-doped carbon modified catalytic ceramic membrane: Synergy of membrane confinement and surface reaction

Abstract

Surface-dependent nonradical oxidation of N-doped carbon (NC)-based peroxymonosulfate (PMS) system features high stoichiometric efficiency and target degradation selectivity. However, these are severely limited by the ineffective mass transfer of organics and PMS to NC surface. Herein, we utilize membrane confinement to enhance the interaction between organics/PMS and NC catalyst, and propose the synergy mechanism of surface reaction and membrane confinement towards organics removal. The NC catalyst layer is firstly uniformly loaded throughout the ceramic membrane (NC@CM) via an innovative simultaneous polymerization-coating method. As expected, NC@CM/PMS system significantly expedites the surface reaction dominant oxidation in the filtration-through mode, and its kinetics constant for bisphenol A removal is 3700 times higher than that of NC powder/PMS system. Moreover, it has high selectivity in removal of targeted organics such as BPA (81–100 % removal rate) under various interferences (anions, NOM, water sources) due to the corporation of surface reaction and membrane sieving effect. Mechanism study reveals that the synergy of membrane confinement and surface reaction of NC@CM/PMS system removes large size disturbance and reinforces mass transfer process of reactive species towards target organics, and promotes the generation and transformation of reactive species on the NC surface. Our system can selectively and efficiently remove targeted micropollutants with strong anti-interference capability, which is of great significance in practical application.