Desorption of Intrinsic Cesium from Smectite: Inhibitive Effects of Clay Particle Organization on Cesium Desorption

详细信息    查看全文

• 作者：Keisuke Fukushi ; Haruka Sakai ; Taeko Itono ; Akihiro Tamura ; Shoji Arai
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：September 16, 2014
• 年：2014
• 卷：48
• 期：18
• 页码：10743-10749
• 全文大小：389K
• ISSN：1520-5851

文摘

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鈥搈ontmorillonite 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 Ca²⁺ and Mg²⁺ (>0.5 mM) and high concentrations of K⁺. The order of ability for Cs desorption was Na⁺ = K⁺ > Ca²⁺ = Mg²⁺ 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.