Dependence of bisphenol A photodegradation on the initial concentration of oxalate in the lepidocrocite-oxalate complex system.
To understand the degradation of endocrine disrupting chemicals (EDCs) in natural environment with existence of iron oxides and carboxylic acids, the dependence of bisphenol A (BPA) photodegradation on the initial concentration of oxalate (COX) in lepidocrocite (gamma-FeOOH) aqueous suspension was investigated under both UV and visible lights in this study. Lepidocrocite powder was home-prepared by a hydrothermal process. It was found that BPA degradation was promoted greatly in the presence of oxalate owing to the formation of lepidocrocite-oxalate complex. And there was an optimal COX, which was 2.0 and 2.4 mmol/L, under UV and visible lights, respectively. The first-order kinetic constant, k value increased 38 times from 0.17 x 10(-2) min(-1) in the absence of oxalate to 6.39 x 10(-2) min(-1) in the presence of oxalate with an optimal COX (2.0 mmol/L) under UV irradiation, and almost 306 times from 0.02 x 10(-2) min(-1) in the absence of oxalate to 6.11 x 10(-2) min(-1) in the presence of oxalate with an optimal COX (2.4 mmol/L) under visible irradiation. The BPA degradation rate increased and the first-order kinetic constants decreased with the increase in BPA initial concentration. The dependence of the variation of pH value, total-Fe and Fe2+ during the photoreaction on COX was also investigated. The pH value increased obviously with the reaction time. Total-Fe increased dramatically at the first 5 min and then decreased quickly under UV irradiation and slowly under visible irradiation. The initial concentration of oxalate is a main factor to affect BPA photodegradation in aqueous suspension under both UV and visible lights.
Dong
Jun
J
School of Life Science, Sun Yat-sen University, Guangzhou, China.
Li
Fang-bai
FB
Lan
Chong-yu
CY
Liu
Cheng-shuai
CS
Li
Xiao-min
XM
Luan
Tian-gang
TG
D001559:Benzhydryl Compounds; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010070:Oxalates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D010782:Photolysis; D013472:Sunlight; D014466:Ultraviolet Rays; D018508:Water Purification / Q000379:methods*; D000098826:Bisphenol A Compounds
D001559:Benzhydryl Compounds; D010070:Oxalates; D010636:Phenols; C006780:bisphenol A; D000098826:Bisphenol A Compounds