Enhancing the performance of catalytic membranes for simultaneous degradation of dissolved organic phosphonates and phosphorous recovery: A fit-for-purpose loose nanofiltration design

Abstract

In this study, we developed a loose nanofiltration catalytic membrane (LNCM) by incorporating nitrogen-doped carbon nanotubes (NCNT) into graphene oxide (GO) membrane (NCNT@GO-M) to activate peroxymonosulfate for efficient phosphonates degradation into phosphate, reducing phosphorus-based pollution and facilitating P recovery. The NCNT@GO-M exhibited superior permeability (76.7 L m−2 h−1 bar−1) due to its expanded pore size (1.60 nm). It integrated nanoconfinement and surface catalysis, improving the availability of surface-bound sulfate radicals for rapid Orth-P generation (kobs, 1.93 s−1), with the kobs being 2.4 times higher than that of the NCNT membrane catalytic system and 2626 times higher than the NCNT@GO heterogeneous catalytic system. The NCNT@GO-M also demonstrated excellent antifouling, self-cleaning, and anti-interference ability, effectively retaining humic acid with a molecular weight exceeding 3.6 kDa (∼62% removal of dissolved organic carbon), making it suitable for real-water applications. The development of LNCM shows great potential for transforming and recovery of the nutrients in wastewater.