Study on the solubility parameter of supercritical carbon dioxide system by molecular dynamics simulation

Abstract The enhancement of the solubility parameter of supercritical carbon dioxide plays pivotal role in the application of extraction operation. The solubility parameter of supercritical CO 2 solvent (SC-CO 2 ) and supercritical CO 2 with cosolvent (SC-CO 2 -cosolvent) system have been studied using the molecular dynamics simulations (MD). The calculated results reveal that the solubility parameters of pure SC-CO 2 solvent and SC-CO 2 -cosolvent both reduce with the raising of temperature, enhance with the raising of pressure, and boost linearly with the raising of their density. The adding of the cosolvent (methanol, ethanol, acetone and cyclohexane) into the SC-CO 2 system can enhance the solubility parameter of SC-CO 2 solvent significantly, and the solubility parameter boosts with the raising of the cosolvent concentration. The cosolvent effect on solubility parameter of SC-CO 2 solvent decreases in the order: methanol, ethanol, acetone, cyclohexane. The hydrogen bonding ability of the cosolvent has significant effect on solubility parameter of SC-CO 2 solvent via the strengthening of the interactions among the CO 2 and cosolvent molecules.