Mechanistic insight into degradation of endocrine disrupting chemical by hydroxyl radical: An experimental and theoretical approach

Advanced oxidation processes (AOPs) based on formation of free radicals at ambient temperature and pressure are effective for treating endocrine disrupting chemicals (EDCs) in waters. In this study, we systematically investigated the degradation kinetics of bisphenol A (BPA), a representative EDC by hydroxyl radical ((OH)-O-center dot) with a combination of experimental and theoretical approaches. The second-order rate constant (k) of BPA with (OH)-O-center dot was experimentally determined to be 7.2 +/- 0.34 x 10(9) M-1 s(-1) at pH 7.55. We also calculated the thermodynamic and kinetic behaviors for the bimolecular reactions by density functional theory (DFf) using the M05-2X method with 6-311++G** basis set and solvation model based on density (SMD). The results revealed that H-abstraction on the phenol group is the most favorable pathway for (OH)-O-center dot. The theoretical k value corrected by the Collins-Kimball approach was determined to be 1.03 x 10(10) M-1 s(-1), which is in reasonable agreement with the experimental observation. These results are of fundamental and practical importance in understanding the chemical interactions between (OH)-O-center dot and BPA, and aid further AOPs design in treating EDCs during wastewater treatment processes. (C) 2017 Elsevier Ltd. All rights reserved.