Аннотация:The сoupled solution-diffusion model based on the Maxwell-
Stefan theory was developed to describe the solute rejection from
dilute nonelectrolyte solutions by polymeric membranes applied in
organic solvent nanofiltration. In certain cases, the advanced equation
for the solute rejection can be reduced to the familiar expressions
of the solution-diffusion and the Spiegler-Kedem models. The
model was verified by the experimental results on the dyes nanofiltration
through poly(1-trimethylsilyl-1-propyne) and poly(4-methyl-
2-pentyne) membranes. Two binary separating systems were considered:
first, the dilute ethanol solutions of three dyes with virtually
the same molecular weight, and second, the selected dye dissolved in
three different solvents. In contrast to the solution-diffusion model,
the proposed approach provides an accurate description of both
positive and negative solute rejection as a function of the transmembrane
pressure. The contribution from the coupled solute flux to the
total solute flux was quantitatively estimated. It is shown that the
coupled solute flux becomes predominant over the direct diffusion
flux when the membrane Peclét number reached the values of 1–2.