Preparation and CWPO intensification mechanism of a gradient long-effective catalytic membrane with high-strength and anti-deposition properties

With the rapid development of modern industry, organic contamination has caused various environmental problems. Catalytic wet peroxide oxidation (CWPO) has been regarded as a green and efficient method for pollutant treatment. However, achieving a satisfactory balance between the catalytic activity and stability of the catalysts remains a critical challenge. Herein, to resolve this trade-off and achieve process intensification, a novel porous Fe-polyacrylonitrile (PAN) membrane was fabricated by a one-step cryogenic auxiliary electrospinning method. During synthesis, nanoscale zero-valent iron (NZVI) can be uniformly entrapped within the PAN fiber, and the porous fibrous structure can be formed simultaneously. The synergistic “freezing effect” and “confining effect” reduced diffusion resistance and enhanced contact efficiency, endowing the membrane with high catalytic activity, as evidenced by a pollutant conversion exceeding 95% within 4 min. Pollutant degradation was driven by electronic attraction and nucleophilic attack from oxidative radicals. The process followed 2^nd kinetics, with reactive oxygen species (ROS) playing an essential role. Both experimental identification of intermediates and theoretical DFT calculations elucidated the intensification mechanism of the CWPO reaction over the Fe-PAN. Excellent stability and reusability were further achieved by the synergistic interaction between PAN and NZVI. The Box-Behnken design was subsequently employed to optimize the degradation process, with the optimal conditions identified as lower pH, moderate temperature, and intermediate oxidant level. By revealing the intensification property of the Fe-PAN membrane in catalytic reactions, this study facilitates development in the fabrication of catalytic membranes. It is expected to serve as technical guidance for developing chemical processes that are efficient, safe and environmentally benign, contributing to water environmental security and human health protection.