DIFFUSION-COEFFICIENTS OF NAPHTHALENE AND DIMETHYLNAPHTHALENE IN SUPERCRITICAL CARBON-DIOXIDE

A new experimental apparatus based on a pseudo-steady state solid diss olution method has been designed to measure the diffusion coefficients of supercritical carbon dioxide(1)-naphthalene(2) and supercritical c arbon dioxide(1)-dimethylnaphthalene isomers(2) systems. The diffusion coefficients were measured at 308.2 K. In order to establish the vali dity of this method and the performance of the apparatus, the experime ntal results of the diffusion coefficients of naphthalene in supercrit ical carbon dioxide were compared with the literature data measured by other methods. The decrease of diffusion coefficient of naphthalene w as observed near the critical point of carbon dioxide, The diffusion c oefficients of 2,6-dimethylnaphthalene (2,6-DMN) and 2,7-dimethylnapht halene (2,7-DMN) show almost the same values. The diffusion coefficien ts of these isomers are about 10% lower than those of naphthalene. (C) 1998 Elsevier Science B.V.