Formation of genotoxic quinones during bisphenol A degradation by TiO2 photocatalysis and UV photolysis: A comparative study

• Published in: Applied catalysis. B, Environmental Environmental, 2014-11, Vol.160-161, p.106-114
• Main Authors: Kondrakov, A.O., Ignatev, A.N., Frimmel, F.H., Bräse, S., Horn, H., Revelsky, A.I.
• Format: Article
• Language: English
• Subjects: Bisphenol A; Photocatalysis mechanism; Quinone; TiO2; Toxicity
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2014.05.007

•BPA removal efficiencies of UV and UV–TiO2 processes were compared.•Five new intermediates were identified, e.g. potentially mutagenic BPA 3,4-quinone.•BPA 3,4-quinone was formed during hole oxidation of BPA onto TiO2 surface.•Scavenging of free OH radicals enhanced BPA 3,4-quinone formation.•Direct UV photolysis formed BPA catechols less harmful as BPA. In this study, a hazardous DNA-binding agent, bisphenol A 3,4-quinone (BPAQ), was detected among products of bisphenol A (BPA) photocatalytic degradation. To clarify the mechanism of BPAQ formation, we investigated BPA degradation by TiO2 photocatalysis and UV photolysis at 254nm in detail. The main focus was given to understanding the roles of OH radicals and photogenerated holes in the evolution of potentially harmful aromatic products. Five new intermediates were identified using an enhanced LC–MS–MS/ToF approach. We found that direct hole oxidation was abundantly responsible for the transformations of BPA into quinone and catechol products. Scavenging of free OH radicals induced a mechanism change and intensified BPAQ formation. Direct UV photolysis produced two catechol derivatives with potentially lower endocrine-disrupting activity in comparison to BPA. Both of the processes demonstrated similar efficiencies in BPA elimination. Complete mineralization was achieved only in the case of TiO2 photocatalysis, but accompanied by potentially genotoxic intermediates formed by hole oxidation.