In situ catalytic ozonation driven by ferrous hydroxyl complex decomplexation for simultaneous removal of heavy metals and organics.

Heavy metals, especially in complexed forms, and organics frequently coexist in industrial wastewater, and the resulting co-contamination poses a significant treatment challenge. Herein, we propose a strategy in which Cu(II)-EDTA is reduced and decomplexed by the ferrous hydroxyl complex to generate copper-iron oxides that in situ catalyze O3 decomposition, producing multiple reactive species for the simultaneous removal of heavy metals and refractory organics. Complete Cu-EDTA removal was achieved within 5 min, and the in situ generated catalyst enabled O3 to fully degrade 1 mM aniline within 30 min, achieving a rate 4.56 times that of O3 alone. Mechanistic analysis reveals that the in situ generated copper-iron oxides accelerate O3 conversion to ·OH, 1O2, and ·O2⁻. Owing to a 2.8-fold increase in ·OH generation, efficient aniline degradation was observed, accompanied by decreased toxicity of major intermediates. Validation with actual electroplating wastewater confirmed complete removal of Cu and aniline and improved COD removal efficiency from 35.9% to 59.2%. By transforming decomplexation products into active catalysts, this strategy enhances catalytic ozonation efficiency and provides a promising solution for the simultaneous treatment of heavy metal and organic co-contamination in wastewater.