Comparison of molecular models used in molecular dynamics simulation for tracer diffusion coefficients of naphthalene and dimethylnaphthalene isomers in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスNVT ensemble molecular dynamics simulation was performed to calculate the tracer diffusion coefficients of naphthalene and dimethylnaphthalene isomers in supercritical carbon dioxide. Carbon dioxide was treated as a Lennard-Jones molecule (single site model) and solutes were treated as a rigid model of multi sites (united atom model) and a flexible model of all atoms (all atom model). The calculated results are compared with the experimental data and the calculated results by a single site model. The united atom model gives the best results to the experimental data among the three models. The calculated tracer diffusion coefficients by the all atom model show fairly good results without adjustable interaction parameters. © 2005 Elsevier B.V. All rights reserved

Solubilities and diffusion coefficients of high boiling compounds in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスA brief introduction of the data sources and the applications of correlation methods for the solubilities and diffusion coefficients of hig-boiling compounds (mainly in solid state) in supercritical carbon dioxide are reviewed. Empirical equations, equations of state, solution models, and the Monte Carlo simulation for the calculation of solubilities in supercritical carbon dioxide are discussed. The application of empirical equation based on the Stokes-Einstein model, rough hard sphere theory, Schmidt number correlation, and molecular dynamics simulation for the calculation of diffusion coefficients in supercritical carbon dioxide at infinite dilution condition are reviewed. Further, the application of the Darken equation and the Leffler and Cullinan equation for the calculation of concentration dependence of diffusion coefficients in supercritical carbon dioxide is presented. © 2001 Elsevier Science Ltd. All rights reserved

Diffusion coefficients of aromatic compounds in supercritical carbon dioxide using molecular dynamics simulation

金沢大学大学院自然科学研究科生産プロセ

Molecular dynamics simulation of diffusion coefficients of naphthalene and 2-naphthol in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスNVT ensemble molecular dynamics simulation has been applied to calculate the diffusion coefficients of naphthalene and 2-naphthol in supercritical carbon dioxide in the pressure range from 8 to 40 MPa under infinite dilution conditions. The Lennard-Jones (12-6) potential function was used as the intermolecular potential. The calculation results showed good agreement with the experimental values, by using the intermolecular interaction parameters between unlike molecules which were determined by Monte Carlo simulation to give good representation for the solubilities of naphthalene and 2-naphthol in supercritical carbon dioxide

Calculation of diffusion coefficients for carbon dioxide + solute system near the critical conditions by non-equilibrium molecular dynamics simulation

金沢大学大学院自然科学研究科生産プロセスA non-equilibrium molecular dynamics simulation was adopted to calculate the diffusion coefficients for a pseudo-binary system of carbon dioxide and for a carbon dioxide + solute system at 308.2 and 318.2K. The calculated results were compared with the self- and tracer diffusion coefficients calculated by an equilibrium molecular dynamics simulation. The simulated results for the pseudo-binary system of carbon dioxide by the non-equilibrium molecular dynamics simulation are in good agreement with the results of self diffusion coefficients for pure carbon dioxide by the equilibrium molecular dynamics simulation. The simulated results of mutual diffusion coefficients for the carbon dioxide + solute system by the non-equilibrium molecular dynamics simulation are slightly lower than the results of the tracer diffusion coefficients by the equilibrium molecular dynamics simulation. The anomalous behavior of diffusion coefficients near the critical concentration was represented by the results of the non-equilibrium molecular dynamics simulation. © 2004 Elsevier B.V. All rights reserved

Molecular dynamics simulation of fluorination effect for solvation of trifluoromethylbenzoic acid isomers in supercritical carbon dioxide

金沢大学大学院自然科学研究科生産プロセスA molecular dynamics (MD) simulation was applied to carbon dioxide + trifluoromethylbenzoic acid isomer and carbon dioxide + methylbenzoic acid isomer systems to investigate the interactions between carbon dioxide and the solutes. The pair correlation functions between the carbon dioxide and trifluoromethyl group or methyl group in the solutes were calculated to study the fluorination effect of solvation. As a result, it was found that the interactions between carbon dioxide and trifluoromethyl group in trifluoromethylbenzoic acid isomers were stronger than those between carbon dioxide and the methyl group in methylbenzoic acid isomers. The simulation results had the same tendency as the experimental solubility enhancements and coincided with the trend of the interaction parameters of the Peng-Robinson equation of state that were determined from the solubility data. © 2005 Taylor & Francis Group Ltd