H3PW12O40/TiO2 catalyst-induced photodegradation of bisphenol A (BPA): Kinetics, toxicity and degradation pathways

Abstract

A series of experiments were conducted to investigate the kinetics of bisphenol A (2,2-bis(4-hydroxyphenyl)propane, BPA) degradation using H3PW12O40/TiO2 (PW12/TiO2) composite catalyst, toxicity of BPA intermediate products and degradation pathways. The results showed that the BPA photodegradation using PW12/TiO2 catalyst followed the first-order kinetics, and under the optimal experimental conditions at H3PW12O40 loading amount of 6.3%, BPA initial concentration of 5mgL−1, and the solution pH of 8.2, the kinetic constant was 3.7-fold larger than that of pristine TiO2. The hydroxyl radicals derived from the electroreduction of dissolved oxygen with electrons via chain reactions was the main reactive oxygen species. According to the identified intermediates, 4-isopropanolphenol, hydroquinone, 4-hydroxybenzoic acid, and phenol, the possible BPA photodegradation pathways were proposed. Upon 12h irradiation, 77% BPA (20mgL−1) was mineralized and the toxicity to Daphnia magna (D. magna) was almost disappeared, implying the strong oxidation ability of PW12/TiO2 catalyst. The studies provide important information about the BPA degradation and promote the technical development for BPA removal.