Tits J, Wieland E, Müller C J, Landesman C, Bradbury M H
Laboratory for Waste Management, Nuclear Energy and Safety Research Department, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
J Colloid Interface Sci. 2006 Aug 1;300(1):78-87. doi: 10.1016/j.jcis.2006.03.043. Epub 2006 Mar 27.
In the present study the binding of strontium with pure calcium silicate hydrates (C-S-H) has been investigated using batch-type experiments. Synthetic C-S-H phases with varying CaO:SiO(2) (C:S) mol ratios, relevant to non-degraded and degraded hardened cement paste, were prepared in the absence of alkalis (Na(I), K(I)) and in an alkali-rich artificial cement pore water (ACW). Two types of experimental approaches have been employed, investigating sorption and co-precipitation processes, respectively. The Sr(II) sorption kinetics were determined as well as sorption isotherms, the effect of the solid to liquid ratio and the composition (C:S ratio) of the C-S-H phases. In addition, the reversibility of the Sr(II) sorption was tested. It was shown that both the sorption and co-precipitation tests resulted in Sr(II) distribution ratios which were similar in value, indicating that the same sites are involved in Sr(II) binding. In alkali-free solutions, the Sr(II) uptake by C-S-H phases was described in terms of a Sr(2+)-Ca(2+) ion exchange model. The selectivity coefficient for the Sr(2+)-Ca(2+) exchange was determined to be 1.2+/-0.3.
在本研究中，采用批量实验法研究了锶与纯硅酸钙水化物（C-S-H）的结合情况。制备了与未降解和已降解的硬化水泥浆体相关的、具有不同CaO:SiO₂（C:S）摩尔比的合成C-S-H相，实验分别在无碱（Na⁺、K⁺）条件下以及富含碱的人工水泥孔隙水（ACW）中进行。采用了两种实验方法，分别研究吸附和共沉淀过程。测定了Sr(II)的吸附动力学、吸附等温线、固液比对C-S-H相吸附的影响以及C-S-H相的组成（C:S比）。此外，还测试了Sr(II)吸附的可逆性。结果表明，吸附和共沉淀试验得到的Sr(II)分配比在数值上相似，这表明参与Sr(II)结合的是相同的位点。在无碱溶液中，C-S-H相对Sr(II)的吸收可用Sr²⁺-Ca²⁺离子交换模型来描述。确定Sr²⁺-Ca²⁺交换的选择性系数为1.2±0.3。
