Coupled Effects of Aging and Weak Magnetic Fields on Sequestration of Selenite by Zero-Valent Iron
Coupled Effects of Aging and Weak Magnetic Fields on Sequestration of Selenite by Zero-Valent Iron
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老化和弱磁场对零价铁螯合亚硒酸盐的耦合影响
DOI：
10.1021/es500958b
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发表时间：
2014-06-03
影响因子：
11.4
通讯作者：
Tratnyek, Paul G.
中科院分区：
文献类型：
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作者：
Liang, Liping;Guan, Xiaohong;Tratnyek, Paul G.
零价铁 (ZVI) 对 Se(IV) 的封存受到老化 ZVI 和弱磁场 (WMF) 的耦合效应的强烈影响。 ZVI 在 pH 6.0 下使用 MES 作为缓冲液老化 6 至 60 小时，使用 WMF 时 Se(IV) 的去除率几乎恒定，但速率常数比不使用时高 10 至 100 倍。 ?CANES分析表明，应用WMF改变了老化6-60小时的ZVI去除Se(IV)的机制，从吸附然后还原变为直接还原。 Se(IV) 去除和 Fe2+ 释放之间的强相关性表明 Fe-0 将 Se(IV) 直接还原为 Se(0)，与 XANES 分析一致。 ZVI磁化强度的数值模拟表明，WMF对Se(IV)螯合的影响主要与ZVI的铁磁性和Fe2+的顺磁性有关。在 WMF 存在的情况下，洛伦兹力会在溶液中产生对流，使扩散层变窄，并产生场梯度力，使顺磁离子（特别是 Fe2+）沿着 ZVI 颗粒表面的较高场梯度移动，从而引起不均匀去钝化，最终导致 ZVI 表面的局部腐蚀。
The sequestration of Se(IV) by zero-valent iron (ZVI) is strongly influenced by the coupled effects of aging ZVI and the presence of a weak magnetic field (WMF). ZVI aged at pH 6.0 with MES as buffer between 6 and 60 h gave nearly constant rates of Se(IV) removal with WMF but with rate constants that are 10- to 100-fold greater than without. ?CANES analysis showed that applying WMF changes the mechanism of Se(IV) removal by ZVI aged for 6-60 h from adsorption followed by reduction to direct reduction. The strong correlation between Se(IV) removal and Fe2+ release suggests direct reduction of Se(IV) to Se(0) by Fe-0 in agreement with the XANES analysis. The numerical simulation of ZVI magnetization revealed that the WMF influence on Se(IV) sequestration is associated mainly with the ferromagnetism of ZVI and the paramagnetism of Fe2+. In the presence of the WMF, the Lorentz force gives rise to convection in the solution, which narrows the diffusion layer, and the field gradient force, which tends to move paramagnetic ions (esp. Fe2+) along the higher field gradient at the ZVI particle surface, thereby inducing nonuniform depassivation and eventually localized corrosion of the ZVI surface.