Elucidating the enhanced role of carbonate radical in propranolol degradation by UV/peroxymonosulfate system.

Carbonate radical (CO3 •- ) has been proved to be an important secondary radical in advanced oxidation processes due to various radical reactions involved HCO3 - /CO3 2- . However, the roles and contributions of CO3 •- in organic micropollutant degradation have not been explored systematically. Here, we quantified the impact of CO3 •- on the degradation kinetics of propranolol, a representative pollutant in the UV/peroxymonosulfate (PMS) system, by constructing a steady-state radical model. Substantially, the measured values were coincident with the predictive values, and the contributions of CO3 •- on propranolol degradation were the water matrix-dependent. Propranolol degradation increased by 130% in UV/PMS system containing 10 mM HCO3 - , and the contribution of CO3 •- was as high as 58%. Relatively high pH values are beneficial for propranolol degradation in pure water containing HCO3 - , and the contributions of CO3 •- also enhanced, while an inverse phenomenon was shown for the effects of propranolol concentrations. Dissolved organic matter exhibited significant scavenging effects on HO• , SO4 •- , and CO3 •- , substantially retarding the elimination process. The developed model successfully predicted oxidation degradation kinetics of propranolol in actual sewage, and CO3 •- contribution was up to 93%, which in indicative of the important role of CO3 •- in organic micropollutant removal via AOPs treatment.