Microwave-assisted synthesis of hierarchical Bi7O9I3 microsheets for efficient photocatalytic degradation of bisphenol-A under visible light irradiation

A simple and energy-saving microwave heating route for rapid synthesis of Bi7O9I3 sheet-like hierarchical architectures has been demonstrated. The visible-light-induced photocatalytic performances of the prepared materials for the degradation of bisphenol-A (BPA, a known endocrine disrupting chemical) are studied systematically. Using Bi7O9I3 photocatalyst synthesized by 400 W microwaves heating 180 s and with a catalyst dosage of 1 g L-1 in 20 mg L-1 aqueous solution of BPA, a degradation percentage of 99% is obtained under visible-light irradiation for 60 min. The photocatalytic reaction follows pseudo first-order kinetics according to the Langmuir-Hinshelwood model, and the reaction rate constant of the optimal sample is over 16 times greater than that of the commercial Degussa P25 catalyst based on TiO2. In addition, two main intermediates are identified using liquid chromatography combined with mass spectrometry (LC-MS) technique, and subsequently, a simple and direct photodegradation mechanism is proposed. Furthermore, the as-synthesized photocatalysts exhibit a high mineralization capacity of BPA and good stability during the photodegradation reaction, suggesting a promising prospect in the practical application of the photodegradation of organic pollutants. (C) 2012 Elsevier B.V. All rights reserved.