Abstract The adsorption of Th(IV) and the structural transformation of phlogopite were explored using batch, extraction, and spectroscopic approaches in this study. The batch experiments showed that ion exchange, surface complexation, and precipitation were predominant for Th(IV) adsorption on phlogopite under the observed pH ranges. XRD patterns showed that phlogopite was indeed transforming into the vermiculite- and/or montmorillonite-like minerals during Th(IV) adsorption, which indicated that the adsorption of Th(IV) could enhance the weathering process of phlogopite. Such weathering process could be attributed to the intercalation of hydrated Th(IV) ions instead of K+ ions locating at the interlayer sites, and then induced the expansion of the interlayer with a d-spacing of ~ 14 A. Higher temperature and initial Th(IV) concentration were benefit for the structural transformation, but the presence of alkaline cations inhibited the expansion process following the order of Rb+ > K+ > Na+ ≈ Li+, which is strictly consistent with their hydrated radii and energy. Fulvic acid (FA) affected the distribution of Th(IV) on phlogopite to a large extent, which induced different adsorption mechanisms for Th(IV) and the alteration process of phlogopite structure. The results clearly showed a positively relationship between the immobilization ability for Th(IV) and alteration degree of phlogopite structure, which is very important to understand the mutual interaction of radionuclides and micaceous minerals in the environment.

中文翻译：

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Th(IV)吸附与金云母结构改变的关系探讨

摘要 本研究采用分批法、萃取法和光谱法研究了Th(IV)的吸附和金云母的结构转变。批量实验表明，在观察到的 pH 范围内，离子交换、表面络合和沉淀对金云母上的 Th(IV) 吸附起主导作用。XRD图谱表明金云母在Th(IV)吸附过程中确实转化为蛭石和/或蒙脱石类矿物，这表明Th(IV)的吸附可以增强金云母的风化过程。这种风化过程可归因于水合 Th(IV) 离子而不是位于夹层位置的 K+ 离子的嵌入，然后诱导夹层膨胀，d 间距约为 14 A。较高的温度和初始 Th(IV) 浓度有利于结构转变，但碱性阳离子的存在抑制了膨胀过程，其顺序为 Rb+ > K+ > Na+ ≈ Li+，这与其水合半径和能量严格一致。富里酸(FA)在很大程度上影响了Th(IV)在金云母上的分布，从而诱导了Th(IV)的不同吸附机制和金云母结构的改变过程。结果清楚地表明，Th(IV)的固定能力与金云母结构的改变程度呈正相关，这对于了解环境中放射性核素与云母矿物的相互作用非常重要。但碱性阳离子的存在抑制了膨胀过程，其顺序为 Rb+ > K+ > Na+ ≈ Li+，这与它们的水合半径和能量严格一致。富里酸(FA)在很大程度上影响了Th(IV)在金云母上的分布，从而诱导了Th(IV)的不同吸附机制和金云母结构的改变过程。结果清楚地表明，Th(IV)的固定能力与金云母结构的改变程度呈正相关，这对于了解环境中放射性核素与云母矿物的相互作用非常重要。但碱性阳离子的存在抑制了膨胀过程，其顺序为 Rb+ > K+ > Na+ ≈ Li+，这与它们的水合半径和能量严格一致。富里酸(FA)在很大程度上影响了Th(IV)在金云母上的分布，从而诱导了Th(IV)的不同吸附机制和金云母结构的改变过程。结果清楚地表明，Th(IV)的固定能力与金云母结构的改变程度呈正相关，这对于了解环境中放射性核素与云母矿物的相互作用非常重要。这引起了对 Th(IV) 的不同吸附机制和金云母结构的改变过程。结果清楚地表明，Th(IV)的固定能力与金云母结构的改变程度呈正相关，这对于了解环境中放射性核素与云母矿物的相互作用非常重要。这引起了对 Th(IV) 的不同吸附机制和金云母结构的改变过程。结果清楚地表明，Th(IV)的固定能力与金云母结构的改变程度呈正相关，这对于了解环境中放射性核素与云母矿物的相互作用非常重要。