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首页> 外文期刊>Environmental Science & Technology >Arsenite Binding to Sulfhydryl Groups in the Absence and Presence of Ferrihydrite: A Model Study
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Arsenite Binding to Sulfhydryl Groups in the Absence and Presence of Ferrihydrite: A Model Study

机译：亚铁酸盐存在下亚砷酸盐与巯基的结合：模型研究

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摘要

Binding of arsenite (As(Ⅲ)) to sulfhydryl groups (S_(otg)(-Ⅱ)) plays a key role in As detoxification mechanisms of plants and microorganisms, As remediation techniques, and reduced environmental systems rich in natural organic matter. Here, we studied the formation of S_(org)(-Ⅱ)-As(Ⅲ) complexes on a sulfhydryl model adsorbent (Ambersep GT74 resin) in the absence and presence of ferrihydrite as a competing mineral adsorbent under reducing conditions and tested their stability against oxidation in air. Adsorption of As(Ⅲ) onto the resin was studied in the pH range 4.0-9.0. On the basis of As X-ray absorption spectroscopy (XAS) results, a surface complexation model describing the pH dependence of As (Ⅲ) binding to the organic adsorbent was developed. Stability constants (log K) determined for dithio ((AmbS)_2AsO~-) and trithio ((AmbS)_3As) surface complexes were 8.4 and 73, respectively. The ability of sulfliydryl ligands to compete with ferrihydrite for As(Ⅲ) was tested in various anoxic mixtures of both adsorbents at pH 7.0. At a 1:1 ratio of their reactive binding sites, R-SH and ≡FeOH, both adsorbents possessed nearly identical affinities for As(Ⅲ). The oxidation of S_(org)(-Ⅱ)-As(Ⅲ) complexes in water vapor saturated air over 80 days, monitored by As and S XAS, revealed that the complexed As(Ⅲ) is stabilized against oxidation (t_(1/2) = 318 days). Our results thus document that sulfliydryl ligands are highly competitive As (Ⅲ) complexing agents that can stabilize As in its reduced oxidation state even under prolonged oxidizing conditions. These findings are particularly relevant for organic S-rich semiterrestrial environments subject to periodic redox potential changes such as peatlands, marshes, and estuaries.
机译：砷（As（Ⅲ））与巯基（S_（otg）（-Ⅱ））的结合在植物和微生物的As解毒机理，修复技术和减少富含天然有机物的环境系统中起着关键作用。在此，我们研究了在还原条件下，在不存在和存在亚铁酸盐作为竞争性矿物吸附剂的情况下，在巯基模型吸附剂（Ambersep GT74树脂）上，S_（org）（-Ⅱ）-As（Ⅲ）配合物的形成，并测试了它们的稳定性防止空气中的氧化。研究了在4.0-9.0的pH范围内As（Ⅲ）在树脂上的吸附。基于As X射线吸收光谱法（XAS），建立了描述As（Ⅲ）与有机吸附剂结合的pH依赖性的表面络合模型。测定的二硫（（AmbS）_2AsO-）和三硫（（AmbS）_3As）表面配合物的稳定性常数（log K）分别为8.4和73。在pH 7.0的两种吸附剂的各种缺氧混合物中，测试了硫代硫酸盐配体与亚铁酸盐竞争As（Ⅲ）的能力。两种吸附剂在R-SH和≡FeOH的反应结合位点为1：1时，对As（Ⅲ）的亲和力几乎相同。在As和S XAS的监测下，水蒸气饱和空气中S_（org）（-Ⅱ）-As（Ⅲ）配合物在80天内的氧化表明，配合物As（Ⅲ）具有稳定的抗氧化性（t_（1 / 2）= 318天）。因此，我们的结果证明，硫醇基配体是具有高度竞争性的As（Ⅲ）络合剂，即使在长时间的氧化条件下，它也可以将As稳定在其还原态。这些发现特别适合经历周期性氧化还原电位变化（例如泥炭地，沼泽和河口）的富含有机元素的半陆地环境。

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  • 来源
    《Environmental Science & Technology》 |2014年第7期|3822-3831|共10页
  • 作者

    Martin Hoffmann; Christian Mikutta; Ruben Kretzschmar;

  • 作者单位

    Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, CHN, CH-8092 Zurich, Switzerland;

    Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, CHN, CH-8092 Zurich, Switzerland;

    Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, CHN, CH-8092 Zurich, Switzerland;

  • 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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  • 正文语种 eng
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