Diffusion in gels

A new method for the determination of diffusion as well as partition coefficients of low molecular weight substances in membranes of polymers was developed, based on the solution of Fick's equation with appropriate boundary conditions (both concentrations variable). On its basis D and k of dilute (0.05%) KCl solutions in swollen hydrophilic gels of different porosity were determined. From the temperature dependence of diffusion coefficients the activation energy of the process was computed and a simple model describing the structure of the heterogeneous membrane was proposed. The diffusion coefficients strongly depend on the structure of the system investigated.