Predicting CO₂–H₂O Interfacial Tension Using COSMO-RS

Abstract

Knowledge about the interaction between fluids and solids and the interfacial tension (IFT) that results is important for predicting behavior and properties in industrial systems and in nature, such as in rock formations before, during, and after CO injection for long-term storage. Many authors have studied the effect of the environmental variables on the IFT in the CO-HO system. However, experimental measurements above CO supercritical conditions are scarce and sometimes contradictory. Molecular modeling is a valuable tool for complementing experimental IFT determination, and it can help us interpret results and gain insight under conditions where experiments are difficult or impossible. Here, we report predictions for CO-water interfacial tension performed using density functional theory (DFT) combined with the COSMO-RS implicit solvent model. We predicted the IFT dependence as a function of pressure (0-50 MPa), temperature (273-383 K), and salinity (0-5 M NaCl). The results agree well with literature data, within the estimated uncertainty for experiments and for molecular dynamics (MD) simulations, suggesting that the model can be used as a fast alternative to time-consuming computational approaches for predicting the CO-water IFT over a range of pressures, temperatures, and salinities.

A Quantum Mechanically Derived Force Field To Predict CO2 Adsorption on Calcite {10.4} in an Aqueous Environment

“…When two components that have different molecular properties mix, the molecules of the component with the lowest surface tension tends to accumulate at the interface between them. This affinity of gaseous CO 2 for the interface with water has been previously reported. − …”

Wetting Properties of the CO2–Water–Calcite System via Molecular Simulations: Shape and Size Effects

“…Figure shows the predicted CO 2 –water interfacial tension as a function of pressure at 308, 323, and 383 K. The qualitative trends of the IFT are correctly predicted: a gradual linear decrease with pressure, a plateau reached at higher P , decreasing IFT with increasing temperature at low and high pressure, and a crossover region at intermediate pressure (though more data need to be collected in this region). Temperature influences the pressure at which the plateau is reached as well as the value of IFT at high pressure.…”

“…33 (open blue pentagons) and Liang et al 37 (closed blue pentagons); 323 K: this study (red diamonds), experimental data from Chiquet et al 10 (closed green diamonds) and Kvamme et al 27 (open green diamonds), and simulation data from Liu et al 30 (blue diamonds); and 383 K: this study (red circles), experimental data from Chiquet et al 10 (green circles), and simulations results of Nielsen et al 8 (open blue circles) and Liang et al 37 (closed blue circles). The black symbols represent the water surface tension calculated by using the IAPWS recommended interpolating equation for the surface tension of ordinary substances 73 Figure 5 shows the predicted CO 2 −water interfacial tension as a function of pressure at 308, 323, and 383 K. The qualitative trends of the IFT are correctly predicted: 74 a gradual linear decrease with pressure, a plateau reached at higher P, decreasing IFT with increasing temperature at low and high pressure, and a crossover region at intermediate pressure (though more data need to be collected in this region). Temperature influences the pressure at which the plateau is reached as well as the value of IFT at high pressure.…”

Structure of Nanoparticles Derived from Designer Surfactant TPGS‐750‐M in Water, As Used in Organic Synthesis

“…All density functional theory calculations were carried out using the Turbomole program, v6.5, with the BP functional, the TZVP basis set, and the COSMO implicit solvent model with an infinite dielectric constant, required for the subsequent COSMO‐RS calculations . Predictions of interfacial tension, using the slightly updated version of the method with geometric averaging of coverages during the IFT iterations are based on the BP‐TZVP‐C1601 parameterization in the COSMOtherm program and the interfacial tension (IFT) model by Andersson et. al For determining the internal structures in large nanoparticles, we used the weight factor functionality in COSMOtherm to model the PEG region and the core region of the surfactant as different molecules.…”