MgO-loaded tubular ceramic membrane with spatial nanoconfinement for enhanced catalytic ozonation in refractory wastewater treatment

Heterogeneous catalytic ozonation (HCO) enables the destruction of organic pollutants in wastewater via oxidation by powerful hydroxyl radicals (·OH). However, the availability of short-lived ·OH in aqueous bulk is low in practical treatment scenarios due to mass transfer limitations and quenching of water constituents. Herein, we overcome these challenges by loading MgO catalysts inside the pores of a tubular ceramic membrane (denoted as CCM) to confine ·OH within the nanopores and achieve efficient pollutant removal. When the pore size of the membrane was reduced from 1000 to 50 nm, the removal of ibuprofen (IBU) by CCM was increased from 49.6 % to 90.2 % due to the enhancement of ·OH enrichment in the nanospace. In addition, the CCM exhibited high catalytic activity in the presence of co-existing ions and over a wide pH range, as well as good self-cleaning ability in treating secondary wastewater. The experimental results revealed that ·OH were the dominant reactive oxygen species (ROS) in pollutant degradation, while surface hydroxyl groups were active sites for the generation of ·OH via ozone decomposition. This work provides a promising strategy to enhance the utilization of ·OH in HCO for the efficient degradation of organic pollutants in wastewater under spatial confinement.