Uptake of cesium and strontium cations by potassium-depleted phlogopite
Uptake of cesium and strontium cations by potassium-depleted phlogopite
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DOI：
10.1016/j.clay.2005.10.008
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发表时间：
2006-03
影响因子：
5.6
通讯作者：
S. A. Stout;Yunchul Cho;S. Komarneni
中科院分区：
文献类型：
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作者：
S. A. Stout;Yunchul Cho;S. Komarneni
在室温下，用1.0 N氯化钠(NaCl) -0.2 N四苯基硼酸钠(NaTPB) -0.01 M乙二胺四乙酸二钠（EDTA）溶液平衡云母，几乎完全去除云母层间K（92%）。x射线粉末衍射分析提供了额外的证据，证明水合Na+离子几乎完全取代了层间K+。平衡后，云母的c轴间距从10.0 Å增加到大约12.2 Å。贫k云母的铯和锶离子交换等温线表明，贫k云母对这两种元素具有高度的选择性，Cs+交换容量为1.26 meq/g，为理论阳离子交换容量的65%，Sr2+交换容量为1.94 meq/g，为理论云母交换容量的100%。Kielland图表明，当交换相（X¯Cs）中Cs+的等效交换容量<0.66时，云母对Cs+具有选择性；当X¯Sr<0.41时，云母对Sr2+具有选择性。在大于这些水平的等效分数下，层塌缩和/或位阻效应限制了这些离子向云母层间的扩散。利用XRD对Cs+平衡云母的分析表明，c轴间距发生了坍塌。基于<45 μm贫k云母对Sr2+和Cs+的高选择性，该材料可能被证明是这些放射性同位素的无机离子交换剂。
Phlogopite mica was equilibrated with 1.0 N sodium chloride (NaCl)–0.2 N sodium tetraphenylborate (NaTPB)–0.01 M disodium ethylenediaminetetraacetic acid (EDTA) solution at room temperature resulting in an almost complete removal (92%) of the mica's interlayer K. X-ray powder diffraction analysis provides additional evidence that hydrated Na+ions had almost completely replaced the interlayer K+. Following equilibration, the c-axis spacing of the mica increased from 10.0 Å to approximately 12.2 Å. Cesium and Sr ion exchange isotherms indicate that K-depleted phlogopite is highly selective for both elements, the Cs+exchange capacity is 1.26 meq/g or 65% of the theoretical cation exchange capacity and the Sr2+exchange capacity is 1.94 meq/g or 100% of the theoretical exchange capacity of the mica. Kielland plots indicated that the mica was selective for Cs+when the equivalent exchange capacity of Cs+in the exchanger phase (X¯Cs) was <0.66 and selective for Sr2+when X¯Sr<0.41. At equivalent fractions greater than these levels, layer collapse and/or steric effects limit the diffusion of these ions into the interlayers of the mica. Analysis of the Cs+equilibrated mica utilizing XRD indicated that a collapse of the c-axis spacing had occurred. Based on the high selectivity of <45-μm K-depleted phlogopite for Sr2+and Cs+, this material may prove useful as an inorganic ion exchanger for these radioactive isotopes.