Improving the Reactivity of Zerovalent Iron by Taking Advantage of Its Magnetic Memory: Implications for Arsenite Removal
Improving the Reactivity of Zerovalent Iron by Taking Advantage of Its Magnetic Memory: Implications for Arsenite Removal
复制标题
利用零价铁的磁记忆提高其反应活性：对去除亚砷酸盐的影响
DOI：
10.1021/acs.est.5b02699
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发表时间：
2015-09-01
影响因子：
11.4
通讯作者：
Guan, Xiaohong
中科院分区：
文献类型：
--
作者：
Li, Jinxiang;Shi, Zhong;Guan, Xiaohong
首次采用预磁化的方法提高了零价铁（ZVI）对As（III）的吸附活性。与原始ZVI （Pri-ZVI）相比，预磁化ZVI （magi -ZVI）在pH(ini) 4.0 ~ 9.0范围内对As（III）的去除率更大，并随着预磁化磁场强度的增加而逐渐增加。在柱状试验中，magi - zvi对合成地下水中As（III）的去除效果优于Pri-ZVI，能较长时间保持反应活性。对As（III）处理后的ZVI样品进行Fe - K-edge XAFS分析，发现预磁化促进了ZVI向铁（氢）氧化物的转变，并将腐蚀产物从磁铁矿和磁铁矿转变为蛭石，有利于砷的吸附。砷种类分析表明，预磁化有利于As（III）氧化为As(V)。经过研磨处理的ZVI与magi -ZVI在去除As（III）方面存在很大差异，说明magi -ZVI反应性的提高与磁化过程中ZVI晶粒的物理挤压作用无关。磁- zvi的剩余量与总砷去除速率常数呈正相关，表明磁- zvi的反应性增强主要归因于其磁记忆，即磁- zvi所保留的剩余量。
Premagnetization was employed to enhance the reactivity of zerovalent iron (ZVI) toward As(III) sequestration for the first time. Compared to the pristine ZVI (Pri-ZVI), the rate of As(III) elimination by the premagnetized ZVI (Mag-ZVI) was greater over the pH(ini) range of 4.0-9.0 and increased progressively with increasing intensity of the magnetic field for premagnetization. Mag-ZVI could keep its reactivity for a long time and showed better performance than Pri-ZVI for As(III) removal from synthetic groundwater in column tests. The Fe K-edge XAFS analysis for As(III)-treated ZVI samples unraveled that premagnetization promoted the transformation of ZVI to iron (hydr)oxides and shifted the corrosion products from maghemite and magnetite to lepidocrocite, which favored the arsenic sequestration. The arsenic species analysis revealed that premagnetization facilitated the oxidation of As(III) to As(V). ZVI pretreated with grinding was very different from Mag-ZVI with regard to As(III) removal, indicating that the improved reactivity of Mag-ZVI should not be associated with the physical squeezing effect of the ZVI grains during magnetization. The positive correlation between the remanence of Mag-ZVI and the rate constants of total arsenic removal indicated that the enhanced reactivity of Mag-ZVI was mainly ascribed to its magnetic memory, i.e., the remanence kept by Mag-ZVI.