Improving Fenton-like system with Catechin, an environmental-friendly polyphenol: Effects and mechanism

Fenton-like system had long been modified to promote its adaptability and efficiency by adding extra components like metal chelators or reducers. Nonetheless, chelator such as ethylene diamine tetraacetic acid (EDTA) was harmful in high dosage. While strong reducers could efficiently promote the generation speed of hydroxyl radicals (HO center dot), they could also get oxidized easily during storage time, for which further application was costly. In this study, (+)-catechin (CAT), an environmental- friendly component, was proved to be an efficient promoter of Fenton-like system on Bisphenol A (BPA) degradation. The modified system achieved 92% of BPA removal in one hour. The mechanism was studied, and the reaction procedure between CAT and Fe(III) together with the degradation pathways of CAT were identified. Fe(III) got chelated first by CAT and quickly reduced to Fe(II) via a single inner-compound electron transfer. The intermediates of CAT could further reduce one and a half more potion of Fe(III) on average. Consequently, massive amount of Fe(II) turned Fenton-like procedure to Fenton reaction and thus promoted the generation of HO center dot. The main radicals contributed on BPA degradation was HO center dot. BPA could be efficiently degraded at pH 6.5 or acidic pH range, but the degradation was completely inhibited with the pH higher than 8.0. The optimal mole ratio between Fe(III) and CAT was 6:1 and the degradation pathway of BPA was deduced.