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Sorption of Arsenic(Ⅴ) and Arsenic(Ⅲ) to Schwertmannite

机译:Schwertmannite对砷(Ⅴ)和砷(Ⅲ)的吸附

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摘要

This study describes the sorption of As(Ⅴ) and As(Ⅲ) to schwertmannite as a function of pH and arsenic loading. In general, sorption of As(Ⅴ) was greatest at low pH, whereas high pH favored the sorption of As(Ⅲ). The actual pH of equivalent As(Ⅴ) and As(Ⅲ) sorption was strongly loading dependent, decreasing from pH ~ 8.0 at loadings <120 mmol_(As) mol_(Fe)~(-1) to pH ~ 4.6 at a loading of 380 mmol_(As) mol_(Fe)~(-1). Sorption isotherms for As(Ⅴ) were characterized by strong partitioning to the schwertmannite solid-phase at low loadings and sorption capacities of 225-330 mmol_(As(V)) mol_(Fe)~(-1) at high loadings. In contrast, the As(Ⅲ) isotherms revealed a weak affinity for sorption of As(Ⅲ) versus As(Ⅴ) at low loadings yet a greater affinity for As(Ⅲ) sorption compared with As(Ⅴ) at high loadings (when pH > 4.6). Sorption of As(Ⅴ) and As(Ⅲ) caused significant release of SO_4~(2-) from within the schwertmannite solid-phase, without major degradation of the schwertmannite structure (as evident by X-ray diffraction and Raman spectroscopy). This can be interpreted as arsenic sorption via incorporation into the schwertmannite structure, rather than merely surface complexation at the mineral-water interface. The results of this study have important implications for arsenic mobility in the presence of schwertmannite, such as in areas affected by acid-mine drainage and acid-sulfate soils. In particular, arsenic speciation, arsenic loading, and pH should be considered when predicting and managing arsenic mobility in schwertmannite-rich systems.
机译:这项研究描述了Schwertmannite对As(Ⅴ)和As(Ⅲ)的吸附与pH和砷含量的关系。通常,低pH值对As(Ⅴ)的吸附最大,而高pH值对As(Ⅲ)的吸附有利。当量的As(Ⅴ)和As(Ⅲ)吸附的实际pH值与负载有很大关系,负载<120 mmol_(As)mol_(Fe)〜(-1)时从pH〜8.0降低到pH 4.6时的pH〜4.6。 380mmol(As)mol_(Fe)〜(-1)。低负荷下As(Ⅴ)的吸附等温线具有很强的分配能力,高负荷下吸附量为225-330 mmol_(As(V))mol_(Fe)〜(-1)。相比之下,As(Ⅲ)等温线显示出在低负荷下对As(Ⅴ)的吸附亲和力较弱于As(Ⅴ),但在高负荷下(当pH值下)与As(Ⅴ)相比,对As(Ⅲ)的吸附亲和力更大。 > 4.6)。吸附As(Ⅴ)和As(Ⅲ)导致从Schwertmannite固相内部显着释放SO_4〜(2-),而Schwertmannite结构没有重大降解(通过X射线衍射和拉曼光谱法证明)。这可以解释为通过掺入到schwertmannite结构中而不是仅在矿物质-水界面的表面络合而吸收砷。这项研究的结果对于存在schwertmannite的砷的迁移具有重要意义,例如在受酸性矿物质排放和酸性硫酸盐土壤影响的地区。特别是在预测和管理富含schwertmannite的系统中的砷迁移率时,应考虑砷的形态,砷的含量和pH值。

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  • 来源
    《Environmental Science & Technology》 |2009年第24期|9202-9207|共6页
  • 作者单位

    Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia;

    Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia;

    Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia;

    Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia;

    Monash Centre for Synchrotron Science and School of Chemistry, Monash University, Clayton, VIC 3800, Australia;

    Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia;

    School of Biomolecular and Physical Sciences, Griffith University, Nathan, QLD 4111, Australia;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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