Title: Photocatalytic degradation of bisphenol A as an endocrine disruptor in aqueous suspension using Ag-TiO₂ catalysts

Authors: S. Rengaraj, X.Z. Li

Addresses: Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China. ' Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China

Abstract: A novel photocatalyst, titanium dioxide (TiO₂) deposited with silver (Ag), was prepared by an ultrasonic-assisted sol–gel method and studied for the photocatalytic degradation of endocrine disrupting chemicals such as bisphenol A (BPA) under UV illumination, in order to determine its photocatalytic properties. A series of Ag-TiO₂ catalysts prepared with different Ag dosage were characterised by SEM, EDX, XRD, XPS, and UV–Visible absorption spectroscopy and their photocatalytic activity was evaluated in the degradation of BPA in aqueous suspension. The experiment demonstrated that the presence of Ag in TiO₂ catalysts could enhance the photocatalytic oxidation of BPA in aqueous suspension. It was found that the degradation of BPA by these catalysts followed the first-order kinetic model. The enhanced reduction of oxygen through better electron-hole separation in Ag-TiO₂ particles compared to pure TiO₂ particles increased the rates of BPA degradation. In the reaction of BPA degradation, the presence of two methyl groups in the BPA structure were initially attacked with OH and/or OOH radicals which have strong oxidising power, and then followed by the cleavage of the two phenyl moieties. Finally, the photomineralisation to CO₂ gas occurred via oxidative processes involving carboxylic acids and aldehydes.

Keywords: bisphenol A; photodegradation; Ag deposition; sol–gel; TiO₂; UV light; photocatalytic degradation; endocrine disruptor; aqueous suspension; titanium dioxide; silver; water treatment; wastewater treatment; water pollution.

DOI: 10.1504/IJEP.2006.010451

International Journal of Environment and Pollution, 2006 Vol.27 No.1/2/3, pp.20 - 37

Published online: 24 Jul 2006 *

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