Experimental Measurement of CO₂ Solubility in Aqueous CaCl₂ Solution at Temperature from 323.15 to 423.15 K and Pressure up to 20 MPa Using the Conductometric Titration

Abstract

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.

Modeling of Gas Solubility Using the Electrolyte Cubic Plus Association Equation of State

“…The studies of the ion hydration and ion-H 2 O molecule interactions 122,123 demonstrated that ions with smaller size and higher charge density bind H 2 O molecules stronger, which weakens the capacity of helping solvent trap dissolved gas molecules. Anions usually have larger ionic radii than cations, so the hydration of cations is usually much stronger than that of anions 124 323.15 K 62,65,108,111 .…”

Enhanced gas recovery by CO2 injection: Influence of monovalent and divalent brines and their concentrations on CO2 dispersion in porous media

“…Contrary to the distilled water scenario, the KCl scenario showed an early breakthrough of CO2 albeit an appearance of a gentler curve compared to the others, indicating that the displacement front was wider (Ekwere, 2007) and larger and thus, higher mixing. In terms of solubility, it has been established that CO2 has higher solubility in monovalent salts than divalent salt (Messabeb et al, 2017). Therefore, a possible explanation of this effect observed is that the concentration of the KCl at that ionic strength is higher than the rest, taking into account the nature of the salt.…”

“…This drastic shift from moderate KL for divalent brines to high values can be attributed to salting out effects. Salting out effect is defined as the relative reduction of CO2 solubility in aqueous solutions containing salts compared to CO2 solubility in pore water (Messabeb et al, 2017). And divalent salts lead to more salting out than monovalent salts.…”

Experimental Determination of CO2Solubility in Brines At High Temperatures and High Pressures and Induced Corrosion of Materials in Geothermal Equipment

“…Although many data are available in the literature for the CO2 solubility in pure water or single salt solutions, data for carbon dioxide solubility in mixed-salt solutions are still missing. The aim of this study was to use a simple method developed in previous papers [4,5] to determine the carbon dioxide solubility in brines at high temperatures and high pressures.…”