Solubility of Flue Gas or Carbon Dioxide-Nitrogen Gas Mixtures in Water and Aqueous Solutions of Salts: Experimental Measurement and Thermodynamic Modeling

Over the past few decades, development of innovative techniques for carbon capture and storage (CCS) from power plant flue gas has become imperative due to substantial increase in the global atmospheric concentration of greenhouse gases, particularly anthropogenic CO ₂ . In this regard, it is of utmost importance to have accurate thermodynamic experimental data along with reliable predictive models to be used in the novel CCS techniques such as hydrate-based geological storage methods. In this study, we introduced a new approach to accurately measure the solubility of three different types of simulated power plant flue gases, including coal-fired flue gas, gas-fired flue gas, and syngas, in water and aqueous solutions of NaCl. To mimic real operational conditions, the solubility measurements were carried out over a temperature range from 273.25 to 303.05 K and pressures up to 22 MPa with 5, 10, and 15 wt % NaCl. The experimental data were presented in conjunction with thermodynamic predictions. To predict the solubility of CO ₂ and N ₂ in water and brine, we applied three different equations of state, including CPA-SRK72, VPT, and PC-SAFT, with adjusted binary interaction parameters (BIPs) using a wide range of available experimental data. Good agreement between the predictions and the experimental results confirms the reliability of the thermodynamic model. We also performed a series of sensitivity analyses to identify the accuracy range of each EOS in terms of pressure, temperature, and salinity.