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Zusammenfassung:
The mechanical permeability and the reflection coefficient at 1 atm and 20°C as well as the solute rejection efficiency at 50 and 100 atm are determined for aqueous solutions of HCl, NaCl, MgCl2, and AlCl3 over a wide concentration range using a strong anion exchange membrane. Systems with positive reflection coefficients yield a positive solute rejection. Therefore, the solute concentration of the filtrate is smaller than that of the phase under hydrostatic pressure. Just the reverse is true for systems with negative reflection coefficients. These observations are in complete agreement with theoretical predictions based on thermodynamics of irreversible processes as well as on the quantitative treatment of the model of membranes with narrow pores. – Experimentally found differences in the concentration dependence of the reflection coefficients between a 2–1-valent (MgCl2) and a 3 – 1 valent (AlCl3) electrolyte are predicted by the model of membranes with narrow pores.
