蒙脱石-氧化铁二元复合胶体吸附钨的研究
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S153

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国家自然科学基金项目(41907015)资助。


Adsorption of Tungsten by Montmorillonite-Iron oxide Binary Complex
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National Natural Science Foundation of China (No. 41907015)

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    摘要:

    本研究选取代表性层状硅酸盐蒙脱石,两种代表性氧化铁(水铁矿、针铁矿),合成蒙脱石-水铁矿、蒙脱石-针铁矿二元复合体,通过宏观吸附以及光谱学技术探究钨(WO42-)在蒙脱石-氧化铁复合体上的吸附行为和潜在机制。结果表明:氧化铁紧密覆盖在蒙脱石表面,使表面颗粒更加细小;钨的吸附量随pH升高而降低,3种吸附剂对钨吸附量大小顺序为:蒙脱石-水铁矿>蒙脱石-针铁矿>蒙脱石;原位红外光谱实验表明,钨在蒙脱石表面主要以外圈络合物形式存在,而在蒙脱石-氧化铁复合体上形成内圈络合物(Fe-O-W),且在低pH时,形成聚合态钨;X-射线光电子能谱进一步表明,针铁矿和水铁矿表面铁羟基参与了钨的络合反应。本研究证实,氧化铁覆盖不仅增大蒙脱石对钨的吸附量,而且使钨由外圈络合物形态转变为内圈络合态,进一步生成聚合态钨。研究结果对预测钨在土壤中的迁移转化、生物有效性和归宿有重要指导意义。

    Abstract:

    In this study, montmorillonite-goethite and montmorillonite-ferrihydrite complexes were synthesized, and batch adsorption experiments combined with various spectroscopies were applied to investigate the binding behaviors and mechanisms of tungsten (WO42-). The results showed that iron oxides could form heterogeneous and fine particles on the surface of montmorillonite, the order of adsorption capacity for tungsten was montmorillonite-ferrihydrite>montmorillonite-goethite complexes> montmorillonite, and the adsorption decreased with increasing pH; In situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy showed that outer-sphere complexes were formed on montmorillonite surface, whereas inner-sphere complexes (Fe-O-W) were formed on montmorillonite-iron oxide complexes. Moreover, tungsten polymerization occured at low pH on iron oxide surface; X-ray photoelectron spectroscopy (XPS) further showed that FeOH groups participate in the binding of tungsten on montmorillonite-iron oxide complexes. In conclusion, the coating of iron oxide on phyllosilicates could enhance tungsten retention, transform tungsten species from outer-sphere to inner-sphere complexes, as well as facilitated the formation of polymeric tungstate, which provided significant guidance for predicting the mobility, bioavailability, and fate of tungsten in soil.

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周敏,徐则林,刘新,杜辉辉.蒙脱石-氧化铁二元复合胶体吸附钨的研究[J].土壤,2022,54(4):810-816. ZHOU Min, XU Zelin, LIU Xin, DU Huihui. Adsorption of Tungsten by Montmorillonite-Iron oxide Binary Complex[J]. Soils,2022,54(4):810-816

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  • 收稿日期:2021-10-28
  • 最后修改日期:2021-12-23
  • 录用日期:2021-12-28
  • 在线发布日期: 2022-08-26
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