Synthesis and mechanistic study of a CuO/Cu2(OH)2CO3 catalyst for rapid peroxymonosulfate activation to efficiently degrade 17α-ethynylestradiol

Abstract

The combination of peroxymonosulfate based advanced oxidation processes (PMS-AOPs) with membrane separation technology has shown considerable potential for the degradation of organic pollutants in wastewater. Herein, a CuO/Cu₂(OH)₂CO₃ composite was synthesized in one step using a microwave-assisted method and employed to activate PMS for the degradation of 17α-ethynylestradiol (EE2)—a common environmental endocrine disruptor—in water. The associated CuO/Cu₂(OH)₂CO₃–PMS system removed 98.13 % of EE2 (3 mg/L) within 8 min, substantially outperforming CuO and Cu₂(OH)₂CO₃ in terms of degradation efficiency. The EE2 removal efficiency of the CuO/Cu₂(OH)₂CO₃–PMS system remained at 95.52 % after five cycles, demonstrating excellent stability. Moreover, this system exhibited good degradation ability for various types of pollutants (Congo red, methylene blue, rhodamine B, and tetracycline hydrochloride). Mechanistic studies indicated that Cu ions on the surface of the CuO/Cu₂(OH)₂CO₃ composite and those partially leached into the associated solution heterogeneously and homogeneously catalyzed PMS activation, respectively; this resulted in the formation of a Cu²⁺/Cu⁺ redox cycle and generation of a series of highly oxidative radicals (•OH, SO₄•⁻, and •O²⁻) and nonradicals (¹O₂), which cooperatively and efficiently degraded EE2 through multiple pathways. Three possible EE2 degradation pathways were analyzed, and the toxicities of the intermediate products were evaluated. Overall, this research provides fundamental insights into the catalytic mechanism of CuO/Cu₂(OH)₂CO₃ for PMS activation and lays the groundwork for future integration into continuous-flow systems for practical wastewater treatment applications.