Iron oxyhydroxide polytype (gamma-, delta- and beta-FeOOH) structures govern Zn mobility

文献类型： 外文期刊

第一作者： Hu, Biyun

作者： Hu, Biyun;Yan, Xinran;Wang, Wentao;Liu, Fan;Yin, Hui;Hu, Biyun;Li, Hui;Li, Yan;Li, Hui;Hong, Mei

作者机构：

关键词： Iron oxyhydroxides; Heavy metal; Isomorphous substitution; Adsorption; Metal mobility

期刊名称：CHEMICAL GEOLOGY （ 影响因子：4.685； 五年影响因子：4.942 ）

ISSN： 0009-2541

年卷期： 2022 年 614 卷

页码：

收录情况： SCI

摘要： Iron oxyhydroxide polytype minerals, such as goethite (alpha-FeOOH), lepidocrocite (gamma-FeOOH), feroxyhyte (delta-FeOOH) and akaganeite (beta-FeOOH), widely exist in terrestrial environments, and play important roles in mediating heavy metal mobility. Previous studies mainly focus on goethite, while the other three polytypes have been rarely explored. In the present work, Zn retention contents and mechanisms in Zn-coprecipitated gamma-, delta-and beta-FeOOH minerals were thoroughly investigated. Additionally, Zn mobility during anoxic incubation of Zn-containing lepidocrocite and feroxyhyte samples was monitored. It demonstrates that, feroxyhyte and lep-idocrocite can accommodate relatively higher amounts of Zn (7.71 +/- 0.20 mol% and 8.56 +/- 0.22 mol% respectively) than akaganeite that retains almost no Zn (0.054 +/- 0.002 mol%). In contrast, Zn has the most significant effect on akaganeite morphology. Part of total Zn is incorporated into the lepidocrocite or feroxyhyte structure by substitution for lattice Fe while the remaining Zn is adsorbed on the mineral surfaces. The different Zn substitution levels in these FeOOH minerals are greatly related with the mineral structures, that is, the ratio of edge-sharing to corner-sharing [FeO6] and thus the spatial freedom, and the pHs of the mineral synthetic so-lutions. During anoxic incubation in the presence of 1 mM Fe2+ at pH 6 +/- 0.05 for 60 d, both Zn-containing lepidocrocite and feroxyhyte keep stable, while the dissolved Zn concentrations rapidly increase at initial stage, then decrease after reaction for 3 d, and increase again from 10 d till to the end. The final Zn release from feroxyhyte (-98%) is much higher than that from lepidocrocite (-30%), probably owing to the higher Fe2+- induced reductive dissolution and desorption rates, and larger amounts of Zn adsorbed on the surfaces of the former. These results help to understand the effects of Zn on the physicochemical properties of FeOOH poly -morphs and the geochemical behaviors of Zn associated with Fe oxyhydroxide minerals.

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