Abstract The elevated level of selenium (Se) in the aqueous system presents long-term ecological risks. Hydroxylated calcined dolomites (HCDs) are considered as potentially sustainable lime sources due to their lower production temperatures and resourceful than lime. In this study, HCDs were developed for the removal of Se contaminated water. The HCDs exhibited a better performance to co-precipitate with Se oxyanions than pure Ca(OH)2. Considering that HCDs consisted of Ca(OH)2 with MgO and Mg(OH)2, the function of Mg compounds was also elaborated by various characterization techniques. Mg compounds were proved to enhance the precipitation process and Se removal. STEM-EDX observation revealed that SeO32– was incorporated into the ettringite structure with Mg compounds, whereas SeO42– exhibited a affinity to Mg compounds. Extended X-ray absorption fine structure (EXAFS) results for the MgO/Mg(OH)2 after the reaction proved that both SeO32– interacted with Mg(OH)2 and MgO via inner-sphere complexes whereas SeO42– formed outer-sphere complexes with these Mg compounds. Besides, Mg compounds also influenced the surface charge of solid residues and thus enhanced SeO32– removal. This study provides a fundamental understanding of the roles of Mg compounds in the removal of Se oxyanions during environmental remediation. Besides, the HCDs were proved to be sustainable Ca sources for waste/wastewater remediation.

中文翻译：

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羟基化煅烧白云石中的镁化合物作为石灰有效且可持续的替代品，以钙矾石的形式沉淀以处理水溶液中的亚硒酸盐/硒酸盐

摘要 水系统中硒 (Se) 水平升高会带来长期的生态风险。羟基化煅烧白云石 (HCD) 被认为是潜在的可持续石灰来源，因为它们的生产温度比石灰低且资源丰富。在这项研究中，开发了 HCD 用于去除 Se 污染的水。与纯 Ca(OH)2 相比，HCD 表现出更好的与 Se 氧阴离子共沉淀的性能。考虑到 HCDs 由 Ca(OH)2、MgO 和 Mg(OH)2 组成，Mg 化合物的功能也通过各种表征技术进行了阐述。Mg 化合物被证明可以增强沉淀过程和 Se 去除。STEM-EDX 观察显示，SeO32– 与镁化合物结合到钙矾石结构中，而 SeO42– 显示出对镁化合物的亲和力。反应后 MgO/Mg(OH)2 的扩展 X 射线吸收精细结构 (EXAFS) 结果证明 SeO32– 通过内球复合物与 Mg(OH)2 和 MgO 相互作用，而 SeO42– 形成外球复合物与这些镁化合物。此外，Mg 化合物还影响固体残留物的表面电荷，从而增强 SeO32- 去除。该研究提供了对 Mg 化合物在环境修复过程中去除 Se 氧阴离子的作用的基本理解。此外，HCD 被证明是废物/废水修复的可持续钙源。Mg 化合物也影响固体残留物的表面电荷，从而增强 SeO32– 的去除。该研究提供了对 Mg 化合物在环境修复过程中去除 Se 氧阴离子的作用的基本理解。此外，HCD 被证明是废物/废水修复的可持续钙源。Mg 化合物也影响固体残留物的表面电荷，从而增强 SeO32– 的去除。该研究提供了对 Mg 化合物在环境修复过程中去除 Se 氧阴离子的作用的基本理解。此外，HCD 被证明是废物/废水修复的可持续钙源。