Degradation of bisphenol A by ozonation and determination of degradation intermediates by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry

In this study, bisphenol A (BPA), an endocrine disrupter, was removed by ozonation process. During ozonolysis, degradation kinetics and degradation intermediates of BPA were determined and degradation stoichiometry was also calculated. The degradation of BPA was found to be optimal at pH 3.0 and BPA solution with 0.509 mM concentration was completely degraded after 25 min ozonation time. The stoichiometric ratio between ozone and BPA were calculated to be 10.30. The pseudo-first order degradation rate constant, k(Obs), decreased in the range of 19.3-13.3 s(-1) when the initial concentration of BPA was raised from 0.051 to 0.509 mM. In addition, the second order rate constant, k(app)(BPA), was also calculated in the range of 2.18 x 10(4)-3.56 x 10(4) M-1 s(-1). Henry's constant, k(H), increased as 5.5% depending on growth of ionic strength of BPA solution during ozonation. As a result of the increase of k(H), dissolved ozone reduced throughout the ozonation. Ten different intermediates occurred during the ozonation of BPA and were identified via GC-MS and LC-MS/MS. Malonic and oxalic acids were observed among the intermediates in the first 5 min of ozonation and taken as markers of mineralization. k'(TOC) value was calculated as 2.11 M-1 min(-1) for BPA mineralization and the mineralization of ozonation was achieved about 30% at the end of 25 min ozonation. (C) 2013 Elsevier B.V. All rights reserved.