Unveiling the density of active sites and spatial confinement mechanism of catalytic ozonation by Fe₂O₃-Al₂O₃ ceramic membranes for water purification

Endocrine disruptors have a long half-life and a wide distribution in surface water. The combination of ceramic membrane and advanced oxidation process is a high-efficient treatment technology for the removal of endocrine disruptors. Herein, a novel one-step co-sintering method using iron oxide and alumina for the fabrication of catalytic ceramic membranes was developed. The iron oxide facilitated the sintering of ceramic membranes and provided active sites alongside the surface of pores for activation of ozone. The catalytic ceramic membrane exhibited a removal efficiency of 83.1 % for a model contaminant of atrazine. Quenching experiment and kinetic model of reactive oxygen species competition demonstrated that hydroxyl radicals contributed 97.1 % to the removal efficiency of atrazine. Based on the isotope tracer test and density functional theory, Fe atoms were proved to be active sites with an adsorption energy of -2.42 eV. The spatial distribution of hydroxyl radicals was visualized using finite element simulations, revealing how both the compressed diffusion layer and the density of active sites influence hydroxyl radical generation within membrane pores. This study highlights the balance between the density of active sites and spatial confinement in regulating reaction kinetics, providing valuable insights for the design of catalytic ceramic membranes using a one-step co-sintering method for surface water treatment applications.