Preparation of CuO-loaded montmorillonite for enhanced carbamazepine degradation under simulated sunlight: Unveiling the role of reactive oxygen species

Abstract

In advanced oxidation processes (AOPs), persulfates (PS) activation generates sulfate radicals (SO₄^•−) and hydroxyl radicals (•OH), which are highly effective in the remediation of organic pollutants in water. However, the degradation mechanism of carbamazepine (CBZ) by the montmorillonite (MMT) and CuO composite-activated PS system remains insufficiently understood. This study systematically explored the effects of catalyst type, initial solution pH, inorganic anions and humic acid (HA) on CBZ degradation under simulated sunlight. The results demonstrated that 70 % CuO/MMT combined with 0.1 mol/L PS achieved a 94.28 % CBZ degradation rate at pH 7.0 within 150 min. The presence of coexisting substances (Cl⁻, NO₃⁻, HCO₃⁻, HA) inhibited CBZ degradation, with higher concentrations leading to reduced efficiency. Chemical probe and quenching experiments identified •OH, SO₄^•−, O₂^•−, and ¹O₂, with ¹O₂ playing a dominant role in enhancing CBZ degradation. Photoelectric characterization revealed that 70 % CuO/MMT exhibits excellent visible light absorption and charge transport performance, facilitating the generation of SO₄^•− and •OH. The primary degradation products of CBZ were oxidation and ring-opening compounds, with ECOSAR modeling indicating their reduced toxicity compared to CBZ. This research provides a foundation for the potential application of MMT composite catalysts in the treatment of organic pollutants in water.