Diffusion coefficients of naphthalene and dimethylnaphthalene in supercritical carbon dioxide

Abstract

A new experimental apparatus based on a pseudo-steady state solid dissolution method has been designed to measure the diffusion coefficients of supercritical carbon dioxide(1)-naphthalene(2) and supercritical carbon dioxide(1)-dimethylnaphthalene isomers (2) systems. The diffusion coefficients were measured at 308.2 K. In order to establish the validity of this method and the performance of the apparatus, the experimental results of the diffusion coefficients of naphthalene in supercritical carbon dioxide were compared with the literature data measured by other methods. The decrease of diffusion coefficient of naphthalene was observed near the critical point of carbon dioxide. The diffusion coefficients of 2,6-dimethylnaphthalene (2,6-DMN) and 2,7-dimethylnaphthalene (2,7-DMN) show almost the same values. The diffusion coefficients of these isomers are about 10% lower than those of naphthalene.

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

“…The simulated results of this work ant literature [6,7] by the single site model are However, the density dependence of diffusion coefficients by the single site model is larger than the experimental results, simulated results by the united atom model and those by the all atom model. As especially shown in Figure 5, the simulated results by the united atom model for dimethylnaphthalene isomers are slightly larger than the results by single site model in previous works [6,7] for 2,6-and 2,7-dimethylnaphthalene and this work for 2,3-dimethylnaphthalene, and are close to the experimental data.…”

“…The simulation for carbon dioxide + 2,3-dimethylnaphthalene system by the single site model of solute was performed in the present work and others were cited from the previous works [6,7]. The energy and size parameters were determined by the critical temperature and pressure as the same procedure reported by the previous works [6,7].…”

“…The energy and size parameters were determined by the critical temperature and pressure as the same procedure reported by the previous works [6,7]. The parameters of single site model for solute used in the present study are listed in …”

“…The interaction parameters were determined to represent the solubility in supercritical carbon dioxide by using Monte Carlo simulation. The details of the Monte Carlo simulation are explained in the previous paper [6,7] and the calculation procedures were reported previously [8]. The systems consist of 108 particles of carbon dioxide in a cubic cell with periodic boundary conditions.…”

“…In previous works [6,7], the authors have applied single site model MD simulation to calculate the tracer diffusion coefficients of aromatic compounds, such as 2,6-and 2,7-dimethylnaphthalene, in supercritical carbon dioxide under the infinite dilution condition.…”