Photooxidation of bisphenol A (BPA) in water in the presence of ferric and carboxylate salts.
In this work, the photooxidation of bisphenol A (BPA), a suspected endocrine disruptor (ED), in water in the presence of ferric and oxalate ions was investigated in a concentric reactor under a 125 W high-pressure mercury lamp (lambda> or = 365 nm). The photooxidation efficiencies were dependent on the pH values and ferric/oxalate concentration ratios (Fe(III)/Ox) in the water, with higher efficiency at pH 3.50+/-0.05 and Fe(III)/Ox 10.0/120.0 micromol l(-1). The initial rate of photooxidation increases with increasing the initial concentration of BPA from 2.0 to 5.0 mg l(-1) while do not change at 5.0 and 10.0 mg l(-1). However, higher removal efficiency of BPA is archived at lower BPA initial concentration over range of 2.0 to 10.0 mg l(-1). For 2.0 mg l(-1) BPA, the initial rate of photooxidation is 0.06 mg l(-1)min(-1). By using UV-Vis spectrum and LC-MS techniques, the predominant photooxidation product BPA-o-catechol was identified and the mechanisms for the oxidative degradation were proposed. When BPA reacted with OH radicals, C atoms in 3-position were added with OH radicals followed by O2 peroxidation and HO2 radical escape. Then catechol derivatives were produced. After that, the two H atoms on the hydroxy group were extracted in two individual steps to form intermediates semiquinone radical and o-quinone. The intermediates underwent further oxidation, benzene ring cleavage and decarboxylation, up to mineralization ultimately.
Zhou
Danna
D
College of Material Science and Chemical Engineering, China University of Geosciences, Wuhan 430074, PR China. zdncug@163.com
Wu
Feng
F
Deng
Nansheng
N
Xiang
Wu
W
D001559:Benzhydryl Compounds; D004968:Estrogens, Non-Steroidal / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D010070:Oxalates / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D010777:Photochemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D000098826:Bisphenol A Compounds
D001559:Benzhydryl Compounds; D004968:Estrogens, Non-Steroidal; D017665:Hydroxyl Radical; D010070:Oxalates; D016877:Oxidants; D010636:Phenols; D014874:Water Pollutants, Chemical; C006780:bisphenol A; D000098826:Bisphenol A Compounds