Diffusion coefficients of aromatics in aqueous solution

Diffusion coefficients of the 12 aromatic compounds phenol, aniline, pyridi ne, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2-chlorophenol, 2-nitrop henol, 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, an d tetramethylammonium perchlorate have been studied where reliable diffusio n 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 co ncentrations studied (0.2 x 10(-4) to 5.8 x 10(-4) mol L-1) the diffusion c oefficient 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 mol ecular size of the aromatic compounds.