A novel combination of oxidative degradation for benzotriazole removal using TiO2 loaded on (FeFe2O4)-Fe-II-O-III@C as an efficient activator of peroxymonosulfate

摘要

A heterogeneous photocatalyst, TiO2-functionalized magnetic activated carbon (T@MPAC), was fabricated as a novel peroxymonosulfate (PMS) activator for improving the oxidative degradation of benzotriazole (BTA) in aqueous media. For characterization of the features of the synthesized catalyst, XRD, FESEM, EDS, BET, TEM, PL and UV-vis DRS techniques were applied. Influence of operating parameters namely solution pH, reaction time and catalyst dosages, PMS and BTA was studied in a batch environment. A plausible oxidation mechanism and reaction pathway for BTA degradation was proposed. Potential catalytic, recyclability, durability and quenching studies were performed. The catalytic activity of T@MPAC in the activation of different oxidants also evaluated. Under optimized conditions, the degradation and mineralization rates of BTA were found to be 71.6 and 38.7%, respectively, after the fifth cycles. The catalytic activity of T@MPAC on BTA degradation was improved with the suitability in order of PMS > persulfate > ozone > H2O2. The trapping experiments confirmed the participation of center dot OH, SO4 center dot-, O-2-center dot radicals as reactive species in the system. Among the reactive species (i.e. center dot OH, SO4 center dot-, O-2 center dot- and holes) included in T@MPAC/PMS/UV system, SO4 center dot- radicals had dominant role in controlling the oxidation reaction. Decreasing the degradation rate in the presence of scavenger agents was as IPA > BQ> t-BuOH>KI. The catalytic performance dropped in the presence of chloride ions, while it was less affected by phosphate, nitrate and sulfate anions. The catalyst showed a good recyclability and stability after five consecutive uses. To conclude, coupling of T@MPAC/UV and PMS can be successfully applied as a novel and effective technique to degrade organic substances in wastewater, due to easy recoverable, high catalytic activity and the cogeneration of different reactive species. (C) 2017 Elsevier B.V. All rights reserved.