STEADY-STATE METHOD FOR MEASUREMENT OF TERNARY LIQUID DIFFUSION

An apparatus for measuring ternary liquid diffusion is described. Steady-state diffusion is established in a vertical column open at both ends to horizontal channels carrying solutions of different compositions. Composition profiles and fluxes are determined by spectrophotometry in situ. From two measurements with different end compositions, the four ternary diffusivities at the common composition are determined. Neither calibration with a system of known diffusivity nor an assumed relation between diffusivity and concentration is required. Diffusivities (mass-fixed, mass per unit volume driving forces) determined at 20.0° C. for 0.326 gram per cc. of benzene (B) and 0.265 gram per cc. of 2-propanol (P) in carbon tetrachloride are DBB = -0.059 ± 0.012, DBP = -0.028 ± 0.009, DPB = -0.006 ± 0.012, and DPP = -0.048 ± 0.009 in square centimeters per hour. An order of magnitude improvement in precision is to be expected by a modification in the technique for flux determination. © 1968, American Chemical Society. All rights reserved.