Modeling the CO₂ Solubility in Aqueous Electrolyte Solutions Using ePC-SAFT

Abstract

Carbon dioxide (CO 2 ) solubility in aqueous electrolyte solutions is of special interest for carbon capture and storage and for biochemical processes, particularly at moderate to high temperatures, pressures, and electrolyte concentrations. Unfortunately, experimental determination at such conditions is rather laborious. Therefore, the ionbased model ePC-SAFT was used in this work to model the CO 2 solubility in such systems over a broad range of conditions. The mixtures under investigation were the basis system CO 2 + water and higher systems containing either NaCl, KCl, MgCl 2 , CaCl 2 , NaNO 3 , KNO 3 , Mg(NO 3 ) 2 , or NaHCO 3 . In the pH range considered in this work (pH < 7), CO 2 dissociation reactions were found to be negligible; thus, only physical interactions were considered. Assuming induced association for CO 2 , binary interaction parameters between CO 2 −water and CO 2 − ion species were determined by fitting to literature data. For this purpose, different literature data sets were compared, and only the most reliable data were used to estimate the binary parameters. ePC-SAFT was found to be able to accurately model the CO 2 solubility in water as well as in aqueous systems containing electrolytes over a broad range of temperatures, pressures, and salt concentrations.

Prediction of salting‐out in liquid‐liquid two‐phase systems with ePC‐SAFT: Effect of the Born term and of a concentration‐dependent dielectric constant

“…In order to obtain good predictions in the phase equilibria calculation of multicomponent systems, it is important to accurately model each of the binary sub-system, as already demonstrated in previous works. [29,30,[83][84][85] Binary interaction parameters between organic solvent and water are available for most of the studied water + organic solvent mixtures, see Table 4. However, binary parameters for water + MEK and water + PPG were missing in the literature and were fitted in this work to LLE data of binary mixtures with water.…”

“…Table 6 provides an overview of the studied systems, the temperature, and the reference of the used experimental data. In order to obtain good predictions in the phase equilibria calculation of multicomponent systems, it is important to accurately model each of the binary sub‐system, as already demonstrated in previous works [29,30,83–85] . Binary interaction parameters between organic solvent and water are available for most of the studied water+organic solvent mixtures, see Table 4.…”

Solubility of CO2 in molten Li2Co3-LiCl

“…On the other hand, considering the laborious experimental conditions to determine the CO2 solubility, some theoretical models were developed and used to model the CO2 solubility in the electrolyte, such as Statistical Associating Fluid Theory (SAFT) [23,24], Cubic-Plus-Association (e-CPA) [25,26], and Mixed-Solvent Electrolyte (MSE) [27]. However, these models have all been applied for the aqueous systems or ionic liquids and few models were focused on the molten salts systems.…”

An Accurate Model to Calculate CO2 Solubility in Pure Water and in Seawater at Hydrate–Liquid Water Two-Phase Equilibrium

“…The CPA EOS [49], as the name suggests, is constructed by incorporating the association term derived from Wertheim's theory into the Cubic EOS. The SAFT-type EOS and CPA EOS have been widely used to model vaporliquid equilibrium of the CO 2 -H 2 O or CO 2 -brine systems [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. Furthermore, many studies tried to combine the SAFT-type EOS or CPA EOS with vdW-P model to calculate three-phase equilibrium of gas hydrates [43,[66][67][68][69][70][71][72][73][74][75].…”