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Abstract:
Using the linear relations of thermodynamics of irreversible processes, the transport coefficients lp,lπ,lπp and σ were measured for an asymmetric cellulose acetate membrane with NaCl, Na2SO4, CaCl2, NaF, and saccharose over the concentration range (0–0.5 mol/l or l mol/l) at 20°C or 25°C. The experimental findings manifest a strong dependence of the three transport coefficients lp,lπ, and linπp on solute concentration. This strong dependence on concentration can be attributed to a concentration gradient within the porous sublayer of the asymmetric membrane. Thereby, it is shown that the transport coefficients of an asymmetric membrane depend on the solute concentration on both sides of the membrane instead of the mean concentration c̄s, as would be the case for a homogeneous membrane.
