Correlation of diffusion coefficients for naphthalene and dimethylnaphthalene isomers in supercritical carbon dioxide

Abstract

An equation proposed by Darken, including the thermodynamic factor and tracer diffusion coefficients of solvent and solute, was adopted to correlate the diffusion coefficients for naphthalene and dimethylnaphthalene isomers in supercritical carbon dioxide and the correlated results were compared with the experimental data. IML equation of state with mixing rules and combining rules containing two adjustable interaction parameters were used for calculation of the thermodynamic factor. By using the interaction parameters adjusted to the solubility data, the concentration dependence of diffusion coefficients and their anomaly near the critical point of carbon dioxide can be quantitatively represented. In order to improve the reliability of experimental results, some re-measured diffusion coefficient data for naphthalene, 2,6-and 2,7-dimethylnaphthalene at 308.2 K, and new data for naphthalene at 318.2 K and for 2,3-dimethylnaphthalene at 308.2 K are presented.2

Concentration dependence of diffusion coefficients for supercritical carbon dioxide + naphthalene system

“…The experimental mole fraction of naphthalene was defined as follows. [12] b : inter-and extra-polated values by data of Akgerman et al [13] c : interpolated values by data of Higashi et al [2] Figure captions …”

“…The Darken equation can be applied to calculate the concentration dependence of diffusion coefficients in supercritical fluid [2].…”

Calculation of diffusion coefficient for supercritical carbon dioxide and carbon dioxide+naphthalene system by molecular dynamics simulation using EPM2 model

“…The calculated result of PVT relationship at 308.2 K and 323.2 K was shown in Figure 2 ( , , , , ) Experimental data [13][14][15][16][17] ( ) simulated by all atom model of naphthalene …”

Direct calculation of mutual diffusion coefficients of binary system using non-equilibrium molecular dynamics simulation

“…Many data of mutual diffusion coefficients for binary system have been reported in the single phase region. The mutual diffusion coefficients are known to have anomalous concentration dependence in the vicinity of critical point of vapor-liquid equilibria (VLE) and at supercritical conditions [1][2][3][4][5][6][7][8]. Such anomalous behavior may appear by the chemical potential (activity and fugacity) gradient which can be represented by a thermodynamic factor [9][10][11][12].…”