Peroxymonosulfate activation by Co3O4 coatings for imidacloprid degradation in a continuous flow-cell reactor under simulated solar irradiation. Issue 2 (April 2023) - Silva, Roberta R.M.
Abstract: In this work, a Co3 O4 coating prepared by precipitation and vacuum filtration was applied to photoactivate peroxymonosulfate (PMS), for the degradation of imidacloprid (IMD) under continuous-flow conditions. The effects of PMS concentration, flow rate, and type of irradiation were evaluated. Under optimal conditions (0.2 gPMS L −1, 0.1 mL min −1, and simulated solar irradiation), 99% IMD photodegradation was achieved after 2 h of operation. The outstanding performance of the Co3 O4 /PMS/solar irradiation process was attributed to the synergistic activation of PMS by Co 2+ and Co 3+ species in the Co3 O4 catalyst and the UV component of solar irradiation, in either the homogeneous phase or following the adsorption of PMS onto Co3 O4 . Quenching experiments revealed that sulfate and superoxide radicals, as well as singlet oxygen, were the main active species responsible for IMD oxidation. Measurements using HPLC-high resolution mass spectrometry enabled the identification of eight intermediate products, allowing the proposal of a degradation pathway. The combination of solar light, Co3 O4, and PMS is a simple and low-cost approach with the potential to treat effluents containing harmful pollutants. Graphical Abstract: ga1 Highlights: Co3 O4 coatings for imidacloprid degradation under continuous flow mode operation. Synergistic PMS activation by cobalt species and the UV component of solar light. 99% removal after 120 min in the Co3 O4 /PMS/full Xe-arc (solar) irradiation system. Sulfate and superoxide radicals along with singlet oxygen as main active species. A plausible degradation pathway for IMD was proposed.