Improving the Reactivity of Zerovalent Iron by Taking Advantage of Its Magnetic Memory: Implications for Arsenite Removal

Jinxiang Li, Zhong Shi, Bin Ma, Pingping Zhang, Xiao Jiang, Zhongjin Xiao, Xiaohong Guan

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

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 pHini 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. (Graph Presented).

Original languageEnglish (US)
Pages (from-to)10581-10588
Number of pages8
JournalEnvironmental Science and Technology
Volume49
Issue number17
DOIs
StatePublished - Sep 1 2015
Externally publishedYes

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