In the cement system, hydrocalumite is a candidate adsorbent for low-level ¹²⁹I anionic species. However, the stability of hydrocalumite after immobilizing I⁻ is unclear when they are exposed to pedosphere characterized by organic substances derived from living organisms. In the present work, five amino acids were selected as simplified models of natural organic substances under alkaline conditions. L-cysteine (H₂Cys) and L-aspartic acid (H₂Asp) accelerated the release of I⁻ from I-hydrocalumite through ion-exchange. Ion-exchange of Cys²⁻ with I⁻ in I-hydrocalumite was faster than Asp²⁻, and the interlayer spacing (d₀₀₃) of Cys-hydrocalumite was smaller than that of Asp-hydrocalumite. DFT simulations not only supported the above results but also predicted that there was a positive correlation between the formation energies and interlayer spacings of amino acids intercalated hydrocalumite, depending on the configurations. Moreover, in the DFT predictions, the interaction between amino acids and metallic hydroxide layers was responsible for the formation of hydrogen bonds and Ca-O chemical bonds between the -COO⁻ groups and [Ca₂Al(OH)₆]⁺. The other three amino acids did not show intercalation through ion-exchange. The stability of I-hydrocalumite is influenced differently by coexisting amino acids, depending on the ionic sizes, charge numbers, and hydrophilicity, which cause the second contamination.

中文翻译：

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氨基酸对水铝石中碘化物迁移率的影响

在水泥体系中，水铝石是低水平¹²⁹ I 阴离子物质的候选吸附剂。然而，当它们暴露于以来自活生物体的有机物质为特征的土壤圈时，水铝石在固定 I ^-后的稳定性尚不清楚。在目前的工作中，选择了五种氨基酸作为碱性条件下天然有机物质的简化模型。L-半胱氨酸（H ₂ Cys）和L-天冬氨酸（H ₂ Asp）通过离子交换加速了I ^-从I-水铝钙石的释放。在I-水铝钙石中Cys ²⁻与I ^{- 的}离子交换速度比Asp ²⁻快，层间距（dCys-水铝钙石的₀₀₃ )小于Asp-水铝钙石。DFT 模拟不仅支持上述结果，而且还预测氨基酸嵌入水铝钙石的形成能与层间距之间存在正相关，具体取决于配置。此外，在 DFT 预测中，氨基酸和金属氢氧化物层之间的相互作用是 -COO ^-基团和 [Ca ₂ Al(OH) ₆ ] ⁺之间形成氢键和 Ca-O 化学键的原因. 其他三种氨基酸没有通过离子交换表现出嵌入。I-水铝钙石的稳定性受共存氨基酸的不同影响，取决于引起二次污染的离子大小、电荷数和亲水性。