Surface Catalyzed Oxidative Oligomerization of 17尾-Estradiol by Fe3+-Saturated Montmorillonite

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• 作者：Chao Qin ; Diego Troya ; Chao Shang ; Sherry Hildreth ; Rich Helm ; Kang Xia
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：January 20, 2015
• 年：2015
• 卷：49
• 期：2
• 页码：956-964
• 全文大小：472K
• ISSN：1520-5851

文摘

With widespread detection of endocrine disrupting compounds including hormones in wastewater, there is a need to develop cost-effective remediation technologies for their removal from wastewater. Previous research has shown that Fe³⁺-saturated montmorillonite is effective in quickly transforming phenolic organic compounds such as pentachlorophenol, phenolic acids, and triclosan via surface-catalyzed oligomerization. However, little is known about its effectiveness and reaction mechanisms when reacting with hormones. In this study, the reaction kinetics of Fe³⁺-saturated montmorillonite catalyzed 17尾-estradiol (尾E2) transformation was investigated. The transformation products were identified using liquid chromatography coupled with mass spectrometry, and their structures were further confirmed using computational approach. Rapid 尾E2 transformation in the presence of Fe³⁺-saturated montmorillonite in an aqueous system was detected. The disappearance of 尾E2 follows first-order kinetics, while the overall catalytic reaction follows the second-order kinetics with an estimated reaction rate constant of 200 卤 24 (mmol 尾E2/g mineral)^鈭?聽h^鈥?. The half-life of 尾E2 in this system was estimated to be 0.50 卤 0.06 h. 尾E2 oligomers were found to be the major products of 尾E2 transformation when exposed to Fe³⁺-saturated montmorillonite. About 98% of 尾E2 were transformed into 尾E2 oligomers which are >10⁷ times less water-soluble than 尾E2 and, therefore, are much less bioavailable and mobile then 尾E2. The formed oligomers quickly settled from the aqueous phase and were not accumulated on the reaction sites of the interlayer surfaces of Fe³⁺-saturated montmorillonite, the major reason for the observed >84% 尾E2 removal efficiency even after five consecutive usages of the same of Fe³⁺-saturated montmorillonite. The results from this study clearly demonstrated that Fe³⁺-saturated montmorillonite has a great potential to be used as a cost-effective material for efficient removal of phenolic organic compounds from wastewater.