A comparative study on Fe(III)/H2O2 and Fe(III)/S2O82- systems modified by catechin for the degradation of atenolol

Abstract

The processes of Fe(III) activated persulfate (PS) and H₂O₂ 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 H₂O₂ (Fe(III)/H₂O₂/CAT) systems were compared using atenolol (ATL) as a model contaminant. 91.0% of ATL degradation was reached after 60 min in H₂O₂ system which was much higher than that in PS system (52.4%) under the same experimental condition. CAT could react directly with H₂O₂ to produce small amounts of HO^• and the degradation efficiency of ATL was proportional to CAT concentration in H₂O₂ system. However, the optimal CAT concentration was 5 μM in PS system. The performance of H₂O₂ system was more susceptible to pH than that of PS system. Quenching experiments were conducted indicating that SO₄^•- and HO^• were produced in PS system while HO^• and O₂^•- accounted for ATL degradation in H₂O₂ system. Seven pathways with nine byproducts and eight pathways with twelve byproducts were put forward in PS and H₂O₂ 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 H₂O₂ systems respectively.

Keywords: Fenton-like; Hydrogen peroxide; Persulfate; Polyphenol; Radicals.