Jarosite, a common mineral in acidic sulfur-rich environments, can strongly sorb both As(V) and Sb(V). However, little is known regarding the mechanisms that control simultaneous co-sorption of As(V) and Sb(V) to jarosite. We investigated the mechanisms controlling As(V) and Sb(V) sorption to jarosite at pH 3 (in dual and single metalloid treatments). Jarosite was found to sorb Sb(V) to a greater extent than As(V) in both single and dual metalloid treatments. Relative to single metalloid treatments, the dual presence of both As(V) and Sb(V) decreased the sorption of both metalloids by almost 50%. Antimony K-edge EXAFS spectroscopy revealed that surface precipitation of an Sb(V) oxide species was the predominant sorption mechanism for Sb(V). In contrast, As K-edge EXAFS spectroscopy showed that As(V) sorption occurred via bidentate corner-sharing complexes on the jarosite surface when Sb(V) was absent or present at low loadings or by formation of similar complexes on the Sb(V) oxide surface precipitate when Sb(V) was present at high loadings. These results point to a novel mechanism by which Sb(V) impacts the co-sorption of As(V). Overall, these findings highlight a strong contrast in the sorption mechanisms of Sb(V) versus As(V) to jarosite under acidic environmental conditions.

中文翻译：

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砷和锑在黄钾铁矾上的共吸附机制：X 射线吸收光谱研究

黄钾铁矾是富含硫的酸性环境中的一种常见矿物，可以强烈吸附 As(V) 和 Sb(V)。然而，关于控制 As(V) 和 Sb(V) 同时吸附到黄钾铁矾的机制知之甚少。我们研究了控制 As(V) 和 Sb(V) 在 pH 3 下吸附到黄钾铁矾的机制（在双重和单一类金属处理中）。发现黄钾铁矾在单一和双重准金属处理中比 As(V) 吸附 Sb(V) 的程度更大。相对于单一类金属处理，As(V) 和 Sb(V) 的双重存在使两种类金属的吸附降低了近 50%。锑 K 边 EXAFS 光谱表明，Sb(V) 氧化物的表面沉淀是 Sb(V) 的主要吸附机制。相比之下，K-edge EXAFS 光谱表明，当 Sb(V) 不存在或以低负载量存在时，或通过在 Sb(V) 氧化物表面形成类似的复合物，As(V) 吸附通过黄钾铁矾表面上的双齿共角复合物发生当 Sb(V) 以高负载量存在时沉淀。这些结果指出了 Sb(V) 影响 As(V) 共吸附的新机制。总的来说，这些发现突出了酸性环境条件下 Sb(V) 与 As(V) 对黄钾铁矾的吸附机制的强烈对比。