화학공학소재연구정보센터
Journal of Physical Chemistry, Vol.98, No.17, 4702-4706, 1994
Simultaneous Measurement of Mutual Diffusion and Intradiffusion by Taylor Dispersion
The interdiffusion coefficient (mutual diffusion coefficient) and water intradiffusion coefficient of binary aqueous solutions can be measured simultaneously by Taylor dispersion. A sample of solution containing H2O + solute + HDO is injected into a carrier solution of H2O + solute. The change in refractive index across the dispersed sample is measured downstream from the point of injection. Fitting two Gaussians to the refractive-index profile gives both the H2O-solute interdiffusion coefficient and the H2O-HDO intradiffusion coefficient. The procedure is tested on binary aqueous solutions of sucrose and urea, and then used to measure diffusion in binary aqueous solutions of polyethylene glycol. Dissolving long-chain polyethylene glycols in water increases the solution viscosity substantially, but the water intradiffusion coefficient is almost independent of the viscosity and polymer molecular weight if the concentration of -OCH2CH2- monomer groups is held constant.