U(VI) adsorption on mudstone in the presence of carbonate: Batch experiments, modeling, cryo-TRLFS and PARAFAC analysis

IF 5.8 2区地球科学 Q2 CHEMISTRY, PHYSICAL

Applied Clay Science Pub Date : 2025-07-28 DOI:10.1016/j.clay.2025.107944

Huiyang Mei , Noboru Aoyagi , Takumi Saito , Kazuya Tanaka , Yuki Sugiura , Yukio Tachi

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引用次数: 0

Abstract

Dissolved inorganic carbon (DIC) present in groundwaters near geological disposal site may affect the migration and fate of released radionuclides (e.g., uranium). However, it is still unclear how DIC affects the sorption of U(VI) on mudstone, a potential choice for host rock formation barriers, and the characteristics of U(VI) adsorption species. In view of this, adsorption of U(VI) on mudstone as a function of pH or the DIC level was investigated through batch adsorption experiments, component additivity (CA) modeling, and parallel factor (PARAFAC) analysis of cryogenic time-resolved laser fluorescence spectroscopy (cryo-TRLFS). The inhibition effect of DIC on adsorption of U(VI) was deduced from the batch experimental results. The CA model considering montmorillonite and illite as the main phases responsible for adsorption reflected the variation trend but underestimated the experimental data. Three components were decomposed from the PARAFAC analysis of the cryo-TRLFS data of mudstone and adsorption samples. Based on the spectral shapes, lifetimes, and variation trends, two components were assigned to the naturally occurring U(VI) species in the mudstone matrix and the third component to a ternary uranyl‑carbonate surface species. The obtained results imply a significant influence of the DIC level on retention and fate of U(VI), which needs to be considered in safety assessment of potential deep geological disposal schemes.

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碳酸盐存在下泥岩对U（VI）的吸附：批量实验、建模、cro - trlfs和PARAFAC分析

地质处置场址附近地下水中的溶解无机碳（DIC）可能影响释放的放射性核素（如铀）的迁移和命运。然而，DIC如何影响U（VI）在泥岩上的吸附，以及U（VI）吸附物种的特征仍不清楚。泥岩是寄主岩层屏障的潜在选择。鉴于此，通过间歇吸附实验、组分可加性（CA）建模和低温时间分辨激光荧光光谱（cro - trlfs）平行因子（PARAFAC）分析，研究了泥岩对U（VI）的吸附随pH或DIC水平的变化规律。从批量实验结果推断出DIC对U（VI）吸附的抑制作用。考虑蒙脱土和伊利石为主要吸附相的CA模型反映了变化趋势，但低估了实验数据。对泥岩和吸附样品的cro - trlfs数据进行PARAFAC分析，分解出三个组分。根据光谱形状、寿命和变化趋势，确定了泥岩基质中自然存在的铀（VI）组分和三元碳酸铀酰表面组分的两种组分。所得结果表明，DIC水平对U（VI）的滞留和命运有显著影响，这需要在潜在的深部地质处置方案的安全性评估中加以考虑。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Applied Clay Science 地学-矿物学

CiteScore

10.30

自引率

10.70%

发文量

289

审稿时长

39 days

期刊介绍： Applied Clay Science aims to be an international journal attracting high quality scientific papers on clays and clay minerals, including research papers, reviews, and technical notes. The journal covers typical subjects of Fundamental and Applied Clay Science such as: • Synthesis and purification • Structural, crystallographic and mineralogical properties of clays and clay minerals • Thermal properties of clays and clay minerals • Physico-chemical properties including i) surface and interface properties; ii) thermodynamic properties; iii) mechanical properties • Interaction with water, with polar and apolar molecules • Colloidal properties and rheology • Adsorption, Intercalation, Ionic exchange • Genesis and deposits of clay minerals • Geology and geochemistry of clays • Modification of clays and clay minerals properties by thermal and physical treatments • Modification by chemical treatments with organic and inorganic molecules(organoclays, pillared clays) • Modification by biological microorganisms. etc...