SELF-DIFFUSION COEFFICIENTS OF EACH COMPONENT IN WATER+T-BUTYL ALCOHOL AND WATER+T-BUTYLAMINE BINARY-MIXTURES

The self-diffusion coefficients of water and of the organic component have been measured for H2O+t-butyl alcohol and H2O+t-butylamine mixtures over the whole composition range at 301 K, using the NMR spin-echo technique. In the water-rich region below 20 mol% of cosolvent, the self-diffusion coefficients of both components for each binary solvent system decrease rapidly with increasing cosolvent content. In cosolvent-rich mixtures with more than 50 mol% cosolvent, motions of water are evidently strongly correlated with those of cosolvent molecules. The semiempirical equation proposed by Albright relating the shear viscosity of a mixture to the diffusion coefficients of its components successfully predicts the general shape of the viscosity curve for each binary system. For the composition region above 50 mol% cosolvent the Albright equation gives calculated viscosities which agree well with observed values, but in the water-rich region there are significant deviations between the observed and calculated viscosities.