Influence of Protonation–Deprotonation Reactions on the Diffusion of Ammonium Chloride through Anion-Exchange Membrane

Abstract

Abstract Electrodialytic concentration of ammonium-containing liquid products of biochemical processing of municipal, industrial, and livestock wastewater is a promising method for obtaining cheap liquid fertilizers for agriculture. At the same time, it is known that electrodialysis of NH 4 Cl solutions fails to achieve the same high brine concentrations as in the case of other chlorides, for example, KCl. We show that the reason is high diffusion permeability of anion-exchange membranes (AEMs) to NH 4 Cl, which is due to the protonation–deprotonation reactions of ammonium coions during their transfer from an external solution to an internal AEM solution and vice versa. For the first time, a mathematical model of NH 4 Cl diffusion through AEM was proposed with allowance for these reactions. The experimental values of the diffusion permeability of an anion-exchange membrane AMX and a cation-exchange membrane CMX in NH 4 Cl and KCl solutions have been compared. between The results of calculating the diffusion permeability of the membrane AMX in NH 4 Cl solutions are in qualitative agreement with the experiment data.