Figure 5.

The relationship between the Gibbs–Donnan factor for the reference permeating monovalent (left panel) or bivalent (right panel) cation (for example Na⁺ or Ca²⁺ in a solution with Cl ⁻) and the ratio ${\mathrm{\varphi }}_{\text{np,2}}/{\mathrm{\varphi }}_{\text{np,1}}{\text{= Z}}_{\text{np,2}}{\text{C}}_{\text{np,2}}{\text{/Z}}_{\text{np,1}}{\text{C}}_{\text{np,1}}$ of equivalents of non-permeating species on the two sides of a permselective membrane, calculated according to Eq. (45) for different values of ϕ_np,1 (the case with known total amounts of permeating ions distributed among the two compartments of the same volume, i.e. B = 1).