Investigation of the Solubility Parameter of a Supercritical Carbon Dioxide–Cosolvent System by Molecular Dynamics Simulation

The solubility parameter is a significant constant that could predict whether two substances are miscible. By applying molecular dynamics simulations, the solubility parameters of the SC-CO₂and SC-CO₂–cosolvent were calculated in this work. The solubility parameter was studied concerning temperature, pressure, and density change; 11 various cosolvents were selected to examine the impact of cosolvent concentration and the interaction mechanism between cosolvents and SC-CO₂molecules. The results showed that after adding the cosolvent, the system’s solubility parameter was greatly improved. As the cosolvent concentration increased, the solubility parameter grew. Furthermore, an equation was proposed to accurately predict the SC-CO₂–cosolvent mixed system’s solubility parameter, with a coefficient of determination R²of 0.996. There exists the hydrogen bonding interaction, the van der Waals interaction, and the electrostatic interaction between SC-CO₂and cosolvent. Among them, the hydrogen bonding interaction energy was the most significant factor that helped increase the solubility parameter.