Speciation of Arsenic, Chromium, and Vanadium in Red Mud Samples from the Ajka Spill Site, Hungary
Speciation of Arsenic, Chromium, and Vanadium in Red Mud Samples from the Ajka Spill Site, Hungary
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DOI：
10.1021/es3003475
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发表时间：
2012-03-20
影响因子：
11.4
通讯作者：
Gruiz, Katalin
中科院分区：
文献类型：
--
作者：
Burke, Ian T.;Mayes, William M.;Gruiz, Katalin
结果是基于X射线吸收光谱分析的样品中的铝土矿矿石加工残渣(赤泥)中的砷，铬和钒的形态收集在阿季卡，匈牙利西部的泄漏现场。CrKedge XANES分析发现，铬以Cr3+取代的形式存在于赤铁矿中，这与透射电子显微镜的分析结果一致。V K边XANES谱具有E-1/2位置和前缘特征，与V5+物种的存在相一致，可能与钙铝硅酸盐相有关。作为K-边XANES光谱被鉴定为5+存在。EXAFS分析表明赤泥样品中有砷的物相。当泄漏现场的碱性渗滤液用盐酸中和时，在形成无定形氢氧化铝的过程中，溶液中94%的As和71%的V被去除。对沉淀物中As的EXAFS分析表明，存在砷酸铝-氢氧化物表面络合物。这些结果表明，在近中性的pH条件下，Torna和上Marcal流域的氧化条件、吸收和吸附分别限制了铬和砷的环境迁移性。中和不能有效地从溶液中去除V，因此，赤泥可能是流动V5+的来源，而赤泥沉积物没有从受影响的土地上去除。
Results are presented from X-ray absorption spectroscopy based analysis of As, Cr, and V speciation within samples of bauxite ore processing residue (red mud) collected from the spill site at Ajka, Western Hungary. Cr Kedge XANES analysis found that Cr is present as Cr3+ substituted into hematite, consistent with TEM analysis. V K-edge XANES spectra have E-1/2 position and pre-edge features consistent with the presence of V5+ species, possibly associated with Ca-aluminosilicate phases. As K-edge XANES spectra identified As present as As5+. EXAFS analysis reveals arsenate phases in red mud samples. When alkaline leachate from the spill site is neutralized with HCl, 94% As and 71% V are removed from solution during the formation of amorphous Al-oxyhydroxide. EXAFS analysis of As in this precipitate reveals the presence of arsenate Al-oxyhydroxide surface complexes. These results suggest that in the circumneutral pH, oxic conditions found in the Torna and Upper Marcal catchments, incorporation and sorption, respectively, will restrict the environmental mobility of Cr and As. V is inefficiently removed from solution by neutralization, therefore, the red mud may act as a source of mobile V5+ where the red mud deposits are not removed from affected land.