CoM (M = Mn, Fe, and Cu) LDH-assembled nanoconfined catalytic membranes for efficient micropollutant removal: Performance and atomic-scale mechanism insights

Abstract

Pervasive exposure to different micropollutants (e.g. endocrine disrupting chemicals and pharmaceuticals) present in water environments, presents a notable risk to public health. Herein, three Co-based bimetallic layered double hydroxides (LDHs) were fabricated, then assembled into LDH-based nanoconfined catalytic membranes (CoM_m, M: Fe, Mn, and Cu) with similar structural and physicochemical properties. The micropollutant removal performance of CoM_m in the presence of peroxymonosulfate (PMS) was ranked in the order: CoMn_m > CoFe_m > CoCu_m. The CoMn_m achieved a 100% removal efficiency for pharmaceuticals and endocrine disrupting chemicals, achieving a first-order rate constant (1.64 ms⁻¹ for ranitidine) that was 10²–10⁶ higher than traditional LDH catalysts. Density functional theory (DFT) results revealed that CoMn_m possessed the highest adsorption energy with PMS and d-band centre, exhibiting superior chemisorption activity and faster charge transfer than the other prepared membranes. Furthermore, the nanoconfinement effect within membrane nanochannels contributed to the outstanding performance of CoMn_m. This study provides an atomic-scale understanding of the catalytic mechanisms of CoM_m, guiding the design and optimization of catalytic membranes for water purification.