Tracer diffusion coefficients in water-tri n butylphosphate solutions

The tracer diffusion coefficients of ³H tagged water and ³²P tagged TBP (tri n butylphosphate) in TBP-water mixtures at various temperatures and water concentrations were measured with a modified continually sampled open-ended capillary tube method. The water and TBP tracer-diffusion coefficients measured at 298°K over a range of water concentrations are [given as water molar-fraction X_w D× 10⁶ (cm²-sec^-1)]: 0.51, 4.51, 3.04; 0.44, 4.35, -; 0.39, 3.70, 2.60; 0.30, 3.40, 2.55; 0.10, -, 2.38. The measured water tracer-diffusion coefficients in water saturated TBP measured over a range of temperatures [given as T(^°K), D × 10⁶ (cm²-sec^-1)] are: 293.0, 4.01; 294.4, 4.32; 300.5, 4.98; 303.0, 6.15. From the TBP and water tracer-diffusion coefficient ratios we estimated the relative frictions of the TBP molecules, to that of the water molecules in water-saturated TBP, at 298°K. Results of viscosity measurements in the TBP-water system at various temperatures and water concentrations are also presented.