Degradation of phoxim by ultrasonic assisted calcium sulfite activated persulfate: Kinetics and mechanisms insights

Developing new technologies to address emerging contaminants are urgently needed. To this end, a novel advanced oxidation system (US/CaSO 3 /PDS) utilizing ultrasound to activate persulfate (PDS) and calcium sulfite (CaSO 3 ) for the effective degradation of emerging contaminants was constructed in this study. The pseudo first-order kinetics constant of Phoxim (PHO) can reach 4.3 × 10 −2 min −1 in US/CaSO 3 /PDS system, revealing the prospects for the treatment of pollutants in water. Electron paramagnetic resonance spectra demonstrated that persulfate anion radicals, hydroperoxyl radicals, hydroxyl radicals, and singlet oxygen were produced in the system. Further, quenching experiments and reactive species probes were used to verify the chemical reaction mechanism of this novel system, and the experimental results highlight the key role of 1 O 2 in the degradation of pollutants thanks to the participation of oxygen. In addition, 11 main products in the PHO degradation process were identified by liquid chromatography-high-resolution precise mass spectrometry, and the possible degradation path of PHO in US/CaSO 3 /PDS system was proposed. US/CaSO 3 /PDS system had high pollutant removal efficiency against a variety of emerging pollutants and was applicable in real water matrix. This study provides a new scheme for the development of advanced oxidation technology based on PDS activation for the removal of refractory emerging pollutants in water.