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...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 （y-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 × 10^-2 min^-1 in the absence of oxalate to 6.39 × 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 × 10^-2 min^-1 in the absence of oxalate to 6.11 × 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 Fe^2＋ 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.展开更多
We investigated the reduction of lepidocrocite(γ-FeOOH) by Shewanella oneidensis MR-1 in the presence and absence of Cd. The results showed that Cd^(2+) retarded microbial reduction of γ-Fe OOH and avoided formation...We investigated the reduction of lepidocrocite(γ-FeOOH) by Shewanella oneidensis MR-1 in the presence and absence of Cd. The results showed that Cd^(2+) retarded microbial reduction of γ-Fe OOH and avoided formation of magnetite. The inhibitory effect on γ-Fe OOH transformation may not result from Cd^(2+) toxicity to the bacterium; it rather was probably due to competitive adsorption between Cd^(2+) and Fe^(2+) on γ-Fe OOH as its surface reduction catalyzed by adsorbed Fe^(2+) was eliminated by adsorption of Cd^(2+).展开更多
文摘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 （y-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 × 10^-2 min^-1 in the absence of oxalate to 6.39 × 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 × 10^-2 min^-1 in the absence of oxalate to 6.11 × 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 Fe^2＋ 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.
基金financially supported by the National Natural Science Foundation of China(41601239)the Highlevel Leading Talent Introduction Program of GDAS,the China Postdoctoral Science Foundation(2016M600644)the"Pearl River Talents"Postdoctoral Program of Guangdong Province,and the National Key Research and Development Program of China(2016YFD0800703)
文摘We investigated the reduction of lepidocrocite(γ-FeOOH) by Shewanella oneidensis MR-1 in the presence and absence of Cd. The results showed that Cd^(2+) retarded microbial reduction of γ-Fe OOH and avoided formation of magnetite. The inhibitory effect on γ-Fe OOH transformation may not result from Cd^(2+) toxicity to the bacterium; it rather was probably due to competitive adsorption between Cd^(2+) and Fe^(2+) on γ-Fe OOH as its surface reduction catalyzed by adsorbed Fe^(2+) was eliminated by adsorption of Cd^(2+).
