A comparative study on Fe(III)/HO and Fe(III)/SO systems modified by catechin for the degradation of atenolol.

The processes of Fe(III) activated persulfate (PS) and HO modified by catechin (CAT) had been shown to be effective in degrading contaminants. In this study, the performance, mechanism, degradation pathways and products toxicity of PS (Fe(III)/PS/CAT) and HO (Fe(III)/HO/CAT) systems were compared using atenolol (ATL) as a model contaminant. 91.0% of ATL degradation was reached after 60 min in HO system which was much higher than that in PS system (52.4%) under the same experimental condition. CAT could react directly with HO to produce small amounts of HO and the degradation efficiency of ATL was proportional to CAT concentration in HO system. However, the optimal CAT concentration was 5 μM in PS system. The performance of HO system was more susceptible to pH than that of PS system. Quenching experiments were conducted indicating that SO and HO were produced in PS system while HO and O accounted for ATL degradation in HO system. Seven pathways with nine byproducts and eight pathways with twelve byproducts were put forward in PS and HO systems respectively. Toxicity experiments showed that the inhibition rates of luminescent bacteria were both decreased about 25% after 60 min reaction in two systems. Although the software simulation result showed few intermediate products of both systems were More toxic than ATL, but the amounts of them were 1-2 orders of magnitude lower than ATL. Moreover, the mineralization rates were 16.4% and 19.0% in PS and HO systems respectively.