Modified bentonite-catalyzed oxidation of typical odorous substances in wastewater: comparison of H2O2 and ClO2 systems and mechanism study

In recent years, industrial emissions and waste treatment have increasingly contributed to organic odour pollution, necessitating efficient degradation technologies for typical odorous substances like dimethyl disulfide, trichloroethylene, and p-xylene. This study innovatively employs acid- and iron-modified bentonite (Fe-H-Bent) as a catalyst to enhance the oxidation performance of hydrogen peroxide (H 2 O 2 ) and chlorine dioxide (ClO 2 ) systems, addressing the limitations of low oxidant utilization in conventional methods. By comparing degradation efficiencies, the Fe-H-Bent + ClO 2 system demonstrated superior removal rates (99% for DMDS, 91% for TCE, and 87% for p-xylene under optimal conditions: catalyst-to-oxidant ratio of 1:2, 40 °C, pH = 3), attributed to its enhanced redox potential and catalytic active sites. Mechanistic investigations, combined with electron paramagnetic resonance (EPR) and Fukui function calculations, revealed a dual oxidation pathway: hydroxyl radical (·OH)-mediated attack on methyl-adjacent sites of p-xylene and ClO 2 -driven electron transfer reactions on para-methyl positions, forming intermediates like 2,5-dimethylphenol and alkyl radicals. This work highlights the synergy between modified bentonite and ClO 2 , offering a novel, efficient strategy for odorous substance removal in wastewater treatment, with theoretical insights into radical- and electron-transfer co-oxidation mechanisms.