Osmotic properties of a phenolsulfonic acid formaldehyde cation exchange membrane in contact with mixed aqueous electrolyte solutions

Abstract

Measurements of the reflection coefficient of HCl and CaCl 2 of a phenolsulfonic acid-formaldehyde cation exchange membrane in contact with mixed aqueous electrolyte solutions containing HCl and CaCl 2 are reported. In the system HCl(Δc) CaCl 2 , the reflection coefficient of HCl is found to be positive starting from σ(HCl) ≈ 0.8 and to reach maximum values of about σ( HCl) ≈ +2.1. In the system CaCl 2(Δc) HCl , the reflection coefficient of CaCl 2, starting from σ(CaCl 2) ≈ +0.4 becomes negative with minimum values of about σ(CaCl 2) ≈ −0.7. The composition dependence of σ(HCl) and that of σ(CaCl 2) are discussed in terms of the model of the membrane with narrow pores.