Molecular Dynamics Simulation of CO2-Expanded Liquids

Thermodynamic and transport properties of CO2-expanded methanol system and CO2-expanded ethanol system, as well as the diffusivities of p-chloronitrobenzene/CO2-expanded methanol system and benzonitrile/CO2-expanded ethanol system were modeled with molecular dynamics simulation method. The density data obtained in CO2-expanded methanol system are slightly higher than the experimental ones, while that achieved from CO2-expanded ethanol system are very close to the experimental results. Simulation results show that the volume of methanol or ethanol solutions can be expanded significantly by CO2. When the mole fraction of CO2 reaches 50%, the volume swelling of the solution is 100%. In addition, the diffusion coefficients of CO2, methanol, ethanol, p-chloronitrobenzene and benzonitrile were simulated, in which p-chloronitrobenzene and benzonitrile are similar to experimental data. Finally, viscosities of two expanded liquids are correlated by their diffusion coefficients, which is in agreement with the calculated results of modified Wilke-Chang equation.