Degradation of atrazine by Bi₂MoO₆ activated peroxymonosulfate under visible light irradiation

In this study, bismuth molybdate (Bi₂MoO₆) nanosheets were prepared via a facile hydrothermal method and applied to activate peroxymonosulfate (PMS) for atrazine (ATZ) elimination under visible light irradiation. An effective photocatalytic synergy was observed in vis/Bi₂MoO₆/PMS system. The Bi₂MoO₆ catalyst showed an excellent stability and extremely low metal leaching in the vis/Bi₂MoO₆/PMS system which were characterized by XRD, XPS, HRTEM, SEM and FT-IR technologies. Besides, the influence of operation parameters (i.e., Bi₂MoO₆ dosage, PMS concentration, initial pH, ATZ concentration, co-existing anions, and humic acid) on the removal of ATZ were also investigated in detail. The best ATZ degradation efficiency (> 99 %) was obtained with Bi₂MoO₆ dosage of 0.6 g/L, PMS concentration of 0.8 mM, and ATZ concentration of 2.5 mg/L after 60 min. UV-vis DRS and Mott-Schottky analysis were taken to evaluate the band structure of Bi₂MoO₆. Trapping experiments and EPR detection demonstrated that superoxide radicals, hydroxyl radicals, sulfate radicals and h⁺ both contributed to ATZ degradation, of which hydroxyl radical OH) and h⁺ were the major species. Besides, the performance of vis/Bi₂MoO₆/PMS system for different pollutant removal was also investigated. Finally, the possible degradation products were monitored by UPLC-QTOF-MS/MS and the pathways of ATZ degradation were put forward. Overall, the vis/Bi₂MoO₆/PMS system shows the potential for the removal of organic pollutants in environmental remediation.