Arsenopyrite dissolution in circumneutral oxic environments: The effect of pyrophosphate and dissolved Mn(III).
Arsenopyrite dissolution in circumneutral oxic environments: The effect of pyrophosphate and dissolved Mn(III).
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DOI：
10.1016/j.watres.2023.119595
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发表时间：
2023-01
期刊：
影响因子：
12.8
通讯作者：
Xingxing Wang;Zhipeng Shu;Haohua He;Ming Zhou;Xiaohang Lu;Jiajia Wang;Liwu Zhang;Z. Pan;Zimeng Wang
中科院分区：
文献类型：
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作者：
Xingxing Wang;Zhipeng Shu;Haohua He;Ming Zhou;Xiaohang Lu;Jiajia Wang;Liwu Zhang;Z. Pan;Zimeng Wang
砷黄铁矿（一种重要的砷矿物）在还原条件下的砷氧化溶解对自然水生系统造成环境危害。由于在中性含氧环境中铁氧化物的表面沉淀，毒砂的溶解发生缓慢。然而，天然配体和共存金属的存在可能会改变铁物质的释放，这对于毒砂的溶解至关重要。在这里，我们研究了焦磷酸盐 (PP) 和溶解的 Mn(III) 物质诱导的毒砂的氧化溶解，Mn(III) 物质是一种与 PP 具有强络合亲和力的天然存在的 Mn 物质。随着PP的存在，Fe(II)-PP复合物的形成及其快速氧化为溶解的Fe(III)-PP物质导致在环境黑暗条件下羟基自由基(·OH)的产生大幅增加，从而有助于毒砂更快的溶解和溶解产物中As(V)的更高百分比。溶解的Mn(III)虽然被认为是除氧之外的额外氧化剂，但意外地充当·OH的自由基清除剂并抑制As(V)的产生。此外，两个体系中硫物质的氧化也不同，因为在 PP 存在的情况下观察到硫代硫酸盐的显着形成，而在溶解有 Mn(III) 的体系中则不会发生这种情况。总体而言，溶解的 Mn(III) 和 PP 对毒砂溶解以及随后 Fe、As 和 S 物质转化的影响对于理清这些亚稳态元素之间的相互作用以及评估它们在水生系统中的运输和环境影响具有重要意义。
The oxidative dissolution of As from arsenopyrite, one important arsenic mineral in reducing conditions, poses an environmental hazard to natural aquatic systems. The dissolution of arsenopyrite occurs slowly due to the surface precipitates of iron oxides in circumneutral oxic environments. However, the presence of natural ligands and coexisting metals may change the release of Fe species, which would be of critical importance to the dissolution of arsenopyrite. Here, we investigated the oxidative dissolution of arsenopyrite induced by pyrophosphate (PP) and dissolved Mn(III) species as a natural occurring Mn species with strong complexation affinity to PP. With the presence of PP, the formation of Fe(II)-PP complexes and its rapid oxidation to dissolved Fe(III)-PP species resulted in a substantial increase in the generation of hydroxyl radicals (•OH) under ambient dark conditions, contributing to faster dissolution of arsenopyrite and higher percentage of As(V) in the dissolved products. Dissolved Mn(III), though considered as an extra oxidant besides oxygen, unexpectedly acted as a radical scavenger for•OH and inhibited the production of As(V). Moreover, the oxidation of sulfur species differed in the two systems as significant formation of thiosulfate was observed with the presence of PP, which did not occur in the system with dissolved Mn(III). Overall, the effects of dissolved Mn(III) and PP on the dissolution of arsenopyrite and the subsequent transformation of Fe, As and S species have important implications for disentangling the interactions among these metastable elements, and for assessing their transport and environmental impacts in aquatic systems.