Efficient peroxymonosulfate activation by microscale CuO coated melamine–cyanuric acid supramolecular assembly toward tetracycline degradation

Abstract

For reducing the amount and fully utilizing the active sites of CuO, a microscale CuO coated melamine–cyanuric acid supramolecular assembly (CuO/MCSA) was developed in situ and employed as an efficient peroxymonosulfate (PMS) activator for water decontamination. The characteristics of CuO/MCSA were characterized by XRD, FT-IR, XPS, SEM, TEM and BET. CuO/MCSA showed strong catalytic ability to activate PMS for tetracycline (TC) degradation. Under the conditions of pH ≈ 7 and a PMS dosage of 0.5 mmol L⁻¹, 1 g L⁻¹ of CuO/MCSA including less than 3.0 wt% CuO can remove about 70% of 20 mg L⁻¹ TC within 5 min. After five consecutive cycles, the degradation rate of CuO/MCSA was still around 52.6%. The PMS dosage, reaction temperature, initial pH value, and co-existing anions and small molecule acids all affected the performance of the CuO/MCSA/PMS system in TC degradation. According to quenching experiments and electron paramagnetic resonance (EPR) testing, ¹O₂ played the most important role in TC degradation in the CuO/MCSA/PMS system. In addition, the CuO/MCSA/PMS system exhibited wide applicability, and can effectively remove TC in different water bodies (deionized water, tap water and lake water) and various pollutants (TC, methylene orange and methyl blue). Overall, this work provided an effective strategy to enhance the efficient utilization of a catalyst for PMS activation.