Nonradical-dominated nanoconfined iron single-atom catalytic membrane to enhance peroxymonosulfate activation for efficient water decontamination.

Catalytic membrane reactors (CMRs) exhibit significant advantages in the removal of contaminants of emerging concern. However, the impairment inflicted on polymer membranes by radicals and the radical scavenging induced by natural organic matter constrain the advancement of CMRs. Herein, we designed an iron single-atom catalyst (FePc-O-CNT) dominated by nonradical oxidation mechanisms and combined it with peroxymonosulfate (PMS) to develop a CMR system (FePc-O-CNT membrane/PMS). The system exhibited superior degradation activity to multiple pollutants via nonradical pathways. The nanoconfined membrane space facilitated PMS activation and enhanced singlet oxygen generation and mass transfer, resulting in a 9513-fold enhancement for bisphenol A (BPA) degradation kinetics over the heterogeneous suspensions. Moreover, the system performed robustly in complex water matrices even under severe membrane fouling (60 % or 80 % flux declines). Unlike radical-based processes, the FePc-O-CNT membrane/PMS system maintained excellent permeability, with only a 7.4 % flux loss after 84 h filtration. For engineering validation, the FePc-O-CNT membrane was also fabricated through non-solvent induced phase separation, which achieved ∼100 % BPA removal and minimal iron leaching over 48 h operation. This research introduces a nonradical-dominated CMR system that addresses the limitations of radical-dominated catalytic degradation, providing foundational insights for advanced membrane-based water purification processes.