Abstract In this work, the stability of arsenate adsorbed Mg(II)–Al(III)/Fe(III)–CO3/SO4 Layered Double Hydroxides (LDHs) under three abiotic anoxic reductive conditions that may be encountered in Tailings Management Facilities (TMFs) were evaluated. At pH 8 and 10 mM Fe(II) (aq), the formation of Fe(III)-oxy/hydroxides (FeOHs) occurred for all 5 LDHs but the Fe-based LDHs precipitated the greatest amounts. All LDHs released MgAlFeCO3SO4 > MgAlCO3 > MgFeCO3/MgFeSO4. The solid surfaces remained as As(V) except for MgAlSO4, MgAlCO3, and MgAlFeCO3SO4 LDHs where 10–25% As(III) formed. Finally, at pH 10 and 0.5 mM Fe(II) (aq), the formation of FeOHs occurred to various degrees but a significant amount of CaCO3(s) precipitated. A 2-stage release and re-adsorption mechanism of total As(aq) occurred following the order: MgAlFeCO3SO4 > MgAlSO4 > MgFeCO3 > MgAlCO3 > MgFeSO4. A significant portion of the solid surfaces (30–90%) was found as As(III) for all reacted LDHs. This work provides a guideline for the environmental behavior of As(V) adsorbed LDHs where relevant underwater cover TMF abiotic reducing conditions may exist.

中文翻译：

---

AsO4 吸附的 Mg(II)-Al(III)/Fe(III)-CO3/SO4 层状双氢氧化物的非生物缺氧还原：As 释放和相变的影响

摘要 在这项工作中，砷酸盐吸附的 Mg(II)-Al(III)/Fe(III)-CO3/SO4 层状双氢氧化物 (LDHs) 在尾矿管理设施 (TMFs) 中可能遇到的三种非生物缺氧还原条件下的稳定性) 进行了评估。在 pH 8 和 10 mM Fe(II) (aq) 条件下，所有 5 种 LDH 均形成 Fe(III)-氧/氢氧化物 (FeOH)，但 Fe 基 LDH 的沉淀量最大。所有 LDH 都释放出 MgAlFeCO3SO4 > MgAlCO3 > MgFeCO3/MgFeSO4。除了 MgAlSO4、MgAlCO3 和 MgAlFeCO3SO4 LDHs 形成 10-25% 的 As(III) 外，固体表面仍为 As(V)。最后，在 pH 10 和 0.5 mM Fe(II) (aq) 条件下，FeOH 的形成发生了不同程度，但大量 CaCO3(s) 沉淀。总 As(aq) 的 2 阶段释放和再吸附机制按照以下顺序发生：MgAlFeCO3SO4 > MgAlSO4 > MgFeCO3 > MgAlCO3 > MgFeSO4。对于所有反应的 LDH，大部分固体表面（30-90%）被发现为 As（III）。这项工作为 As(V) 吸附 LDHs 的环境行为提供了指导，其中可能存在相关的水下覆盖 TMF 非生物还原条件。