Efficient and stable flow-through photo-Fenton process at neutral pH using CuO/FeOOH-decorated polymer membranes synthesized via an all-in-one approach

We report an effective (>90 % single-pass removal, 100 L/m 2 h) and stable (24 h) photo-Fenton degradation of tetracycline (TC) at pH 7 in flow-through using porous polyethersulfone (PES) membranes loaded with copper-iron oxide-hydroxide as catalyst. We demonstrated a treatment capacity of 1800 L contaminated water per g metal without performance loss and a turnover frequency (TOF) of 134 µg TC/mg metal/h, surpassing the performance of other state-of-the-art catalytic membranes under neutral conditions. Catalytic membranes with either multi-phase CuO/FeOOH or single-phase Cu 1 Fe 1 O 1 (OH) 3 were synthesized by a resource-efficient all-in-one fabrication established herein, which combines: in situ metallic particle synthesis in the casting solution, membrane preparation via film casting cum phase separation, and room-temperature post-treatment oxidation in water using atmospheric oxygen. Membranes featuring CuO/FeOOH exhibited enhanced photo-Fenton synergy (H 2 O 2 + visible-light), which was attributed to heterojunction formation between FeOOH and CuO particles facilitated by their integrated membrane co-immobilization. Computed band structures suggest effective visible-light-induced electron-hole (e - /h + ) generation by FeOOH and subsequent charge transfer to CuO, which possesses optimal band positioning for activating H 2 O 2 . Charge transfer also significantly enhanced catalyst stability by reducing copper leaching. Scavenger experiments further indicated that e - reduces H 2 O 2 to •OH, while h + oxidizes H 2 O 2 to singlet oxygen ( 1 O 2 ). We also elucidated the link between catalyst dispersion in the polymer matrix and oxidative membrane degradation during water treatment.