OSMOTIC PROPERTIES OF A PHENOLSULFONIC ACID FORMALDEHYDE CATION-EXCHANGE MEMBRANE IN CONTACT WITH MIXED AQUEOUS-ELECTROLYTE SOLUTIONS

Measurements of the reflection coefficient of HCl and CaCl2 of a pheno lsulfonic acid-formaldehyde cation exchange membrane in contact with m ixed aqueous electrolyte solutions containing HCl and CaCl2 are report ed. In the system HCl(Delta c)/CaCl2, the reflection coefficient of HC l is found to be positive starting from sigma(HC) approximate to 0.8 a nd to reach maximum values of about sigma(HCl)approximate to +2.1. In the system CaCl2(Delta c)/HCl, the reflection coefficient of CaCl2, st arting from sigma(CaCl2)approximate to +0.4 becomes negative with mini mum values of about sigma(CaCl2)approximate to -0.7. The composition d ependence of sigma(HCl) and that of sigma(CaCl2) are discussed in term s of the model of the membrane with narrow pores.