Studies on diffusion behavior of dyes in aqueous polymer solutions - Part 3: Diffusion coefficients of dyes in aqueous nonionic polymer solutions

The diffusion coefficients of p-nitroaniline (p-NA) and Orange II(OR-H) in aqueous nonionic polymer solutions, D, and those in water, Do, were measured at 25 degrees C with the diaphragm cell method. The polymers examined were polyethyleneglycol (PEG), polyvinylalcohol(PVA), and polyvinylpyrrolidone(PVP). For PEG, PEG, (degree of polymerization n; 190) and PEG(3) (n; 600), were used. The D/D-0 value in every system decreased with increasing polymer concentration. The decrease in D/D-0 was greater in the order, p-NA < OR-II for dye, and PEG < PVA < PVP for polymer. The decrease in D/D-0 with increasing polymer concentration was explained in terms of the interaction between polymer and dye, and the obstruction to dye diffusion by polymer molecules and water molecules in the neighborhood of polymer molecules. It was shown that the decrease in D/D-0 for PEG1-p-NA and PVP-OR-II systems were almost caused by the interaction between polymer and dye. The D/D-0 values obtained experimentally were in good agreement with those calculated from modified Wang's, Colton's, and Geankoplis's equations, in PEG(1)-p-NA and PVP-OR-II systems.