pH Dependence on Photodecomposition of Bisphenol A at TiO₂/H₂O Intefaces

抄録

Bisphenol A (BPA) widely used includes drain water, consequently causing a serious health threat owing to its endocrine disruptor action. The pH dependence on BPA photodegradation in TiO₂ dispersion under UV-irradiation was examined at different pH in BPA solution (0.1 mM) containing TiO₂ (100 mg). BPA photodegradation was assessed by UV spectroscopy, and total organic carbon (TOC). Change in ζ-potential and ^•OH radicals formation were determined by ESR spin-trapping technique for each solution. Decrease in ratio of UV absorption and TOC at pH 11 occurred more slowly than that at pH 4, 6.3 or 10. This was due to conversion of two -OH groups in BPA to -O₂^- the pH 11. Anionic BPA and negative TiO₂ surface thus separate by simple coulombic force. ^•OH radical intensity at pH 11 was greater than at other values. The photooxidation rate was influenced by the initial absorption between partially charged BPA and TiO₂ surface regardless of the number of ^•OH radicals.