Desorption of intrinsic cesium from smectite: inhibitive effects of clay particle organization on cesium desorption.
Desorption of intrinsic cesium from smectite: inhibitive effects of clay particle organization on cesium desorption.
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DOI：
10.1021/es502758s
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发表时间：
2014-09
影响因子：
11.4
通讯作者：
K. Fukushi;Haruka Sakai;Taeko Itono;A. Tamura;S. Arai
中科院分区：
文献类型：
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作者：
K. Fukushi;Haruka Sakai;Taeko Itono;A. Tamura;S. Arai
核事故后，细粒粘土颗粒在陆地环境中充当放射性铯的迁移介质。由于放射性铯预计将保留在粘土矿物的阳离子交换反应，确定微量铯解吸行为的变化溶液条件是至关重要的。本研究系统地研究了解吸行为的固有Cs（13 nmol/g）在良好的表征钠蒙脱石在电解质溶液（NaCl，KCl，CaCl 2和MgCl 2）在广泛不同的阳离子浓度（0.2 mM至0.2 M）。批式解吸实验表明，在环境相关浓度的Ca（2+）和Mg（2+）（>0.5 mM）和高浓度的K（+）存在下，Cs（+）解吸被显著抑制。在最高阳离子浓度（0.2M）下，Cs的解吸能力顺序为Na（+）= K（+）> Ca（2+）= Mg（2+），这与基于阳离子交换选择性的理论预测相反。激光衍射粒度分析表明，Cs（+）解吸的抑制与粘土类格体尺寸的增加相一致。结果表明，放射性铯在分散的细粘土颗粒粘附在固相时，组织的膨胀粘土颗粒发生，因为在自然过程和人工处理引起的溶液条件的变化。
Fine clay particles have functioned as transport media for radiocesium in terrestrial environments after nuclear accidents. Because radiocesium is expected to be retained in clay minerals by a cation-exchange reaction, ascertaining trace cesium desorption behavior in response to changing solution conditions is crucially important. This study systematically investigated the desorption behavior of intrinsic Cs (13 nmol/g) in well-characterized Na-montmorillonite in electrolyte solutions (NaCl, KCl, CaCl2, and MgCl2) under widely differing cation concentrations (0.2 mM to 0.2 M). Batch desorption experiments demonstrated that Cs(+) desorption was inhibited significantly in the presence of the environmental relevant concentrations of Ca(2+) and Mg(2+) (>0.5 mM) and high concentrations of K(+). The order of ability for Cs desorption was Na(+) = K(+) > Ca(2+) = Mg(2+) at the highest cation concentration (0.2 M), which is opposite to the theoretical prediction based on the cation-exchange selectivity. Laser diffraction grain-size analyses revealed that the inhibition of Cs(+) desorption coincided with the increase of the clay tactoid size. Results suggest that radiocesium in the dispersed fine clay particles adheres on the solid phase when the organization of swelling clay particles occurs because of changes in solution conditions caused by both natural processes and artificial treatments.