Solubility Pattern of CaSO4·2H2O in the System NaCl + CaCl2 + H2O and Solution Densities at 35 °C: Non-ideality and Ion Pairing
Solubility Pattern of CaSO4·2H2O in the System NaCl + CaCl2 + H2O and Solution Densities at 35 °C: Non-ideality and Ion Pairing
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DOI：
10.1021/je0604941
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发表时间：
2007-03
影响因子：
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通讯作者：
Arvind Kumar;and Rahul Sanghavi;V. P. Mohandas
中科院分区：
文献类型：
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作者：
Arvind Kumar;and Rahul Sanghavi;V. P. Mohandas
测定了CaSO4·2H2O在高盐度、35℃恒定CaCl2水溶液中的溶解度。加入CaCl2显著降低了CaSO4·2H2O的溶解度，同时保持了溶解度曲线的基本模式。用扩展的含二次项的德拜-−-休克尔定律计算的CaSO_4·2H_2O的平均离子活度系数随离子强度的增加而减小。将CaSO4·2H2O的热力学溶度积常数值KSP(Th)与从观察到的溶解度数据得到的溶度积KSP进行比较，发现有很大的差异。用扩展的德拜−休克尔定律和离子缔合理论解释了这一现象。我们还测量了四元体系CaSO4·2H2O+NaC l+CaCl2+H2O在35℃时的精确密度，溶液的密度随着浓度的增加而线性增加。含有较高数量的CaCl2的溶液被发现是…
The solubility of CaSO4·2H2O was determined in aqueous NaCl solutions up to very high salinities and constant CaCl2 concentrations at 35 °C. Addition of CaCl2 into the aqueous NaCl system reduces the solubility of CaSO4·2H2O quite dramatically while maintaining the basic pattern of the solubility curve. Mean ionic activity coefficients γ± of CaSO4·2H2O derived using the extended Debye−Huckel law with quadratic terms decrease with an increase in ionic strength. A comparison of the value of the thermodynamic solubility product constant, Ksp(th) of CaSO4·2H2O to the solubility product Ksp obtained from the observed solubility data indicate sizable differences. This has been explained through a combination of the extended Debye−Huckel law and ion association theory. We also measured accurate densities for the quaternary system CaSO4·2H2O + NaCl + CaCl2 + H2O at 35 °C. The density of the solution increases linearly with an increase in concentration. Solutions containing higher amounts of CaCl2 were found to be...