Diffusion coefficients of aromatics in aqueous solution

Diffusion coefficients of the 12 aromatic compounds phenol, aniline, pyridine, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2-chlorophenol, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-cresol, m-cresol, p-cresol, and 3,5-dihydroxytoluol (orcinol) have been measured in aqueous solution at (277.15, 298.15, and 323.15) K using the Taylor dispersion technique. In addition, aqueous solutions of caffeine, benzene, tetraethylammonium perchlorate, and tetramethylammonium perchlorate have been studied where reliable diffusion data are available in the literature in order to test the apparatus. The method provides data with an accuracy to within +/-1.5%. In the range of concentrations studied (0.2 x 10(-4) to 5.8 x 10(-4) mol L-1) the diffusion coefficient depends on the concentration and values at infinite dilution can be obtained by extrapolation. A modified Wilke-Chang equation was found to correlate the data with respect to their dependence on temperature and molecular size of the aromatic compounds.