Abstract
The concentration dependencies of diffusion permeability of homogeneous (AMX-Sb and AX) and heterogeneous (MA-41 and FTAM-EDI) anion-exchange membranes (AEMs) is obtained in solutions of ampholytes (sodium bicarbonate, NaHCO3; monosodium phosphate, NaH2PO4; and potassium hydrogen tartrate, KHT) and a strong electrolyte (sodium chloride, NaCl). It is established that the diffusion permeability of AEMs increases with dilution of the ampholyte solutions, while it decreases in the case of the strong electrolyte solution. The factors causing the unusual form of concentration dependencies of AEMs in the ampholyte solutions are considered: (1) the enrichment of the internal AEM solution with multiply charged counterions and (2) the increase in the pore size of AEMs with dilution of the external solution. The enrichment of the internal solution of AEMs with multiply charged counterions is caused by the Donnan exclusion of protons, which are the products of protolysis reactions. The increase in the pore size is conditioned by the stretching of the elastic polymer matrix due to the penetration of strongly hydrated anions of carbonic, phosphoric, and tartaric acids into the AEMs.
Highlights
The extraction of valuable components and nutrients from urban and industrial sewage and liquid animal wastes, as well as from wastewater of food and pharmaceutical industries, is one of the main trends in modern membrane technology [1,2,3]
We demonstrate in the the section that the contact of anion-exchange membranes (AEMs) with strongly hydrated anions of tartaric, phosphoric, and section that the contact of AEMs with strongly hydrated anions of tartaric, phosphoric, and carboxylic carboxylic acids leads to stretching of the ion-exchange matrix, which reflects in an increase in pore acids leads to stretching of the ion-exchange matrix, which reflects in an increase in pore size and, size and, an increase in diffusion permeability of the membranes
In the case of NaCl solutions, the diffusion permeability of all the membranes decreased with the microheterogeneous model
Summary
The extraction of valuable components and nutrients from urban and industrial sewage and liquid animal wastes, as well as from wastewater of food and pharmaceutical industries, is one of the main trends in modern membrane technology [1,2,3]. ED has shown its usefulness in the extraction of polyprotic carboxylic acids, which are the precursors in biodegradable polymer production, from the products of biochemical processing of biomass [6]; in tartrate stabilization of wine [7]; in peptide fractionation [8]; and in the demineralization of solutions containing amino acids, using, among others, phosphate buffers [9,10]. The development of such technologies is constrained by several challenges. The first of them is related to fouling and destruction of ion-exchange membranes during their long-term operation [11,12,13,14].
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