Diffusion And Osmosis In Potassium Nitrate Synthesis By Electrodialysis Metathesis

The experimental results of the chosen salts permeation with selected heterogeneous and homogenous membranes were analysed as a part of modelling of mass transport in electrodialysis metathesis process (ED-M) for synthesis of KNO3. Heterogeneous membranes swelled more in aqueous solutions and they had higher water uptake than homogeneous membranes. Heterogeneous membranes were also more permeable for both the solute and the solvent, which was attributed to higher solubility of salts in heterogeneous membrane’s material. Diffusion coefficients in ion-exchange membranes tested in this study were found to be dependent on concentration of the upstream solution, with an exception of Ca²⁺ in anion-exchange membranes and NO3^- in cation-exchange membranes. The role of osmosis in water transport in ED-M process was found negligible.