Determination of CO₂ Solubility in Water and NaCl Solutions under Geological Sequestration Conditions Using a Fused Silica Capillary Cell with in Situ Raman Spectroscopy

Abstract

To investigate the solubility of carbon dioxide (CO2) in geological fluids at different temperatures and pressures, we developed a method for measuring solubility using an optically transparent fused silica capillary cell as a high-pressure optical cell combined with Raman spectroscopy under geological sequestration conditions (temperatures of up to 353.15 K and pressure of up to 30.0 MPa). On the basis of the fact that the band intensity of an active Raman species is proportional to its concentration, we determined the linear correlation between the known CO2 concentration and the ratio of the Raman peak heights of CO2 to H2O (νCO2 /νH2O) in homogeneous CO2–H2O and CO2–H2O–NaCl systems. Our results indicate that the Raman peak height ratio is a function of the CO2 concentration and that the pressure and temperature do not significantly affect the relationship between the CO2 concentration and νCO2 /νH2O within the experimental P–T–x conditions. The νCO2 /νH2O values of the CO2-saturated solutions were determined by simulating the CO2 geological sequestration T–P–x conditions. Then, the CO2 solubilities were calculated using the linear relationship. Our results indicate that the method is feasible and that the solubility of CO2 in H2O or NaCl solutions decreases with increasing temperature, increases with increasing pressure, and decreases with increasing salinity. On the basis of a comparison between our experimental data and the results of the previous model, our method provides satisfactory results.

Experimental Measurements of CO2 Solubility in Aqueous MgCl2 Solution at Temperature between 323.15 and 423.15 K and Pressure up to 20 MPa

“…CO2 solubility in single-salt aqueous solutions such as NaCl, CaCl2 and Na2SO4 under CCS conditions is well documented [13][14][15][16][17][18] . The CO2-H2O-NaCl is the most investigated system, more than 1500 solubility points for pressure up 140 MPa, temperature comprises between 273.15-723.15 K and a molality up to 6 mol/kg have been published 4,13,17,[19][20][21][22][23][24][25] . As far as the CO2-H2O-Na2SO4 system is concerned, to our knowledge 450 solubility points are available in the literature for pressure up to 20 MPa, a temperature range of 288.15-423.15 K and a molality 0.1-2.7 mol/kg 18,[26][27][28][29][30][31][32] .…”

Active Nanointerfaces Based on Enzyme Carbonic Anhydrase and Metal–Organic Framework for Carbon Dioxide Reduction

“…A membrane contactor was aimed to allow direct contact of the target gas (CO 2 ) with the enzyme, while the MIL-160 porosity provided a hydrophilic microenvironment to retain immobilized enzyme’s activity. This lab-designed platform was thus hypothesized to directly assist with membrane hydration while also ensuring CO 2 direct adsorption at the CA active site and eliminating the CO 2 solvation [ 91 ] limitations. The mechanism of CO 2 adsorption at the CA active site was previously described, with report showing that CO 2 binds near the Zn ions [ 92 ] to lead to a Zn-coordinated transformation of bound CO 2 into bicarbonate to be followed by the direct release of such product into the media ( Supplementary Materials Equations (S1)–(S3) ) [ 25 ].…”

An improved model for CO2 solubility in aqueous Na+–Cl−–SO42− systems up to 473.15 K and 40 MPa

“…Analyzing the isotherms between 313-393 K for the CO 2 -H 2 O-NaCl system, it is possible to notice more notable deviations between the simulations generated by the model and experimental points of Guo et al (2016) and Wang et al (2019), which can reach up to 7 % and 7.7% respectively.…”

“…The parameters are a function of temperature in addition to being a function of pressure too for these authors. data (Chabab et al, 2019;Drummond, 1981;Guo et al, 2016;Harned and Davis, 1943;He and Morse, 1993;Koschel et al, 2006;Lara Cruz et al, 2020;Malinin and Kurovskaya, 1975;Malinin and Saveleva., 1972;Messabeb et al, 2016;Wang et al, 2019;Yan et al, 2011;Zhao, 2014;Zhao et al, 2015c). Temperatures used in the optimization process (see Table 2).…”

“…J o u r n a l P r e -p r o o f data (Carvalho et al, 2015;Guo et al, 2016;Harned and Davis, 1943;Markham and Kobe, 1941;Rosenqvist et al, 2012;Rumpf et al, 1994;Wang et al, 2019).…”