Efficiently mitigating permeability-reactivity trade-off and membrane fouling on Cu-N-C functionalized ceramic...

Catalytic membrane^- based water treatment technology is subjected to the permeance-reactivity trade-off and unsatisfactory antifouling performance. In this study, a new type Cu-N-C catalytic membrane (CNC) was fabricated by loading Cu-N-C peroxymonosulfate (PMS) catalyst onto both the Al₂O₃ ceramic membrane (CM) surface and its internal pores, aiming to simultaneously enhance permeability, catalytic efficacy and antifouling ability of membrane for improved water treatment. The content of the Cu-N coordination structure (Cu-N_x) was adjusted to research its impact on water treatment. Results showed that Cu introduction significantly enhanced the permeability, pollutant removal efficiency and fouling mitigation of CNC catalytic membrane. The CNC2/PMS system containing most Cu-N_x performed best with almost 100% sulfamethoxazole (SMX) removal within a short residence time of 2.2 min, whose SMX removal efficiency was 2.2 or 2.1 times greater than that of the N-doped carbon/PMS system or CNC2 filtration alone. CNC2/PMS system also exhibited efficient membrane fouling resistance with only less than 5.0% flux loss, thanks to the Cu-induced foulant repulsion and PMS catalytic oxidation. Additionally, CNC2/PMS system maintained high performance over 60 h of continuous operation. The Cu-N_x served as the main active site towards PMS activation for reactive species production (primarily surface-bound SO₄^•- and •OH). The superior catalytic performance of CNC mainly stemmed from the reversible valence cycling of Cu in catalytic layer, in which both PMS and N-doped carbon donated electrons towards Cu center to faciliitated Cu²⁺-to-Cu⁺ converion for sustained PMS activation.