In the framework of the efforts of the scientific community developed for the reduction of CO₂ emissions, the geological storage of CO₂ in deep saline aquifers is under focus. An increase of salinity decreases the potential of CO₂ solubilization into the water. In salty waters, the salinity is not only due to NaCl but also to others ions and in particular Ca and Mg. Experimental solubility data of CO₂ in calcium chloride solution available in the literature at conditions relevant to carbon storage are particularly scarce. In this work, a new analytical method was developed for experimental measurement of CO₂ solubility in calcium chloride solutions (1, 3, and 6 mol/kg) at high pressures (5–20 MPa) and temperatures (323.15, 373.15, and 423.15 K). This method is based on conductometric titration coupled with classical pH titration. The conductimetry shows sharper curves than the pH titration allowing a higher precision. Thirty-six new experimental data are reported in this paper. These data presented an experimental average uncertainty of 2.1% with the ANOVA calculation method based on repeatability and reproducibility experiments. The CO₂ solubility in CaCl₂ solutions is noticeable lower than in NaCl solution increasing the salting out effect. Considering our previous work on NaCl solutions and this paper for CaCl₂ solutions, estimations of the real quantity of CO₂ that may be dissolved in saline aquifers can be made with a significantly better precision.

中文翻译：

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电导滴定法在温度为323.15至423.15 K，压力高达20 MPa的条件下测量CaCl ₂水溶液中CO ₂溶解度的实验

在科学界为减少CO ₂排放量而做出的努力的框架内，深层盐水层中CO ₂的地质储藏成为人们关注的重点。盐度的增加降低了将CO ₂溶解到水中的可能性。在咸水中，盐度不仅归因于NaCl，还归因于其他离子，尤其是Ca和Mg。文献中在与碳储存有关的条件下可获得的实验结果表明，CO ₂在氯化钙溶液中的溶解度数据很少。在这项工作中，为实验测量CO ₂开发了一种新的分析方法。在高压（5-20​​ MPa）和温度（323.15、373.15和423.15 K）下在氯化钙溶液（1、3和6 mol / kg）中的溶解度。该方法基于电导滴定和经典pH滴定。电导率曲线显示出比pH滴定曲线更锐利的曲线，可实现更高的精度。本文报道了三十六项新的实验数据。这些数据基于可重复性和可再现性实验的ANOVA计算方法得出的实验平均不确定度为2.1％。在CaCl ₂溶液中的CO ₂溶解度明显低于在NaCl溶液中的溶解度，从而增加了盐析作用。考虑到我们之前在NaCl溶液方面的工作以及本文针对CaCl _2的研究可以用明显更好的精度估算可能溶解在盐水层中的CO ₂的实际量。