Permeability of membranes containing ionogenic groups

The present paper deals with the transport properties of membranes made of hydrophilic gels containing ionogenic groups. Introduction of ionogenic groups into a gel based on 2-hydroxyethyl methacrylate will affect the permeability of the investigated membranes for sodium chloride by an order or more. Dependences of the permeability on the content of ionogenic groups, three-dimensional network density, and pH were established. The permeability for NaCl was compared for that for bivalent salt (MgSO₄). It is shown, on the basis of independently determined distribution coefficients, that an increase in the permeability of ampholytic membranes in comparison with the neutral ones is primarily due to an increase in the diffusivity of the salt in the membranes with modified structure. It can also be concluded that an approximation of the free volume from the volume of the solvent in the membrane cannot be applied to the poly(2-hydroxyethyl methacrylate) gel.