Heterogeneous catalytic ozonation of bisphenol a with oxygen vacancy-rich montmorillonite supported iron oxide.

Heterogeneous catalytic ozonation is a promising technique for water purification, effectively addressing persistent organic pollutants. This study successfully synthesized oxygen-vacancy-rich Fe2O3/montmorillonite (Fe-MMT-400) nanocomposites via an integrated calcination strategy for enhanced catalytic ozonation of bisphenol A (BPA). Material characterization confirmed the effective structural integration and dispersion of acicular hematite on MMT substrates. XRD, FTIR, and XPS analyses verified the formation of oxygen vacancies (OV), while BET measurements revealed an increased specific surface area, promoting ozone decomposition. In degradation experiments, the Fe-MMT-400/O3 system demonstrated superior performance, achieving 89.9 % BPA removal within 15 min, significantly outperforming ozonation or catalyst-alone systems. Combined electron paramagnetic resonance (EPR) and radical quenching experiments identified surface oxygen atoms (O∗), hydroxyl radicals (•OH), superoxide radicals (O2•-), and singlet oxygen (1O2) as the reactive oxygen species (ROS), with •OH being the dominant oxidative mediator. Furthermore, multidisciplinary characterization through XPS, DFT calculations, and TPD synergistically confirmed that the engineered OVs served as the primary active sites, crucially facilitating ozone adsorption and dissociation. This work ultimately establishes a comprehensive reaction mechanism framework, delineating the surface-mediated radical and non-radical pathways in the heterogeneous catalytic ozonation processes.