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

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