Accelerated degradation of bisphenol A induced by the interaction of EGCG and Cu(II) in Cu(II)/EGCG/peroxymonosulfate process

Abstract

Transition metals to activate peroxymonosulfate (PMS) has promising prospect to remove emerging organic contaminants, among which copper is an alternative because of its relatively high regulated concentration in drinking water and wide use of organic copper pesticide. Cu(I) shows good performance on the activation of PMS, while Cu(II) is reported to have no ability to activate PMS, which is the most stable valent in natural environment. In this study, degradation of bisphenol A (BPA) by Cu(II)/PMS process was significantly enhanced with involvement EGCG, because Cu(II) was transformed to Cu(I) and chelated by EGCG. Batch experiments were conducted to investigate the impacts of Cu(II), EGCG and PMS concentration and co-existing components including natural organic matters, alkalinity, and chloride ion. The impacts of solution pH and dissolved oxygen on BPA degradation were also evaluated to interpret the roles of Cu(I) and superoxide radical in Cu(II)/EGCG/PMS process, and the generated concentration of Cu(I) was determined. Possible generation pathway of Cu(III) were also proposed. By quenching experiment and electron paramagnetic resonance analysis, hydroxyl radical and sulfate radical in Cu(II)/EGCG/PMS process were confirmed to be main contributors for BPA degradation. Furthermore, transformation products of BPA were identified and their respective eco-toxicities were calculated. This work aims to unravel the interaction of EGCG and Cu(II), and provide a deep insight to the copper conversion in the presence of EGCG and PMS.