Separation of small organic ions from salts by ion‐exchange membrane in electrodialysis

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Electrodialysis (ED) can be applied in the food and fermentation industry for separating inorganic salts and organic ions from other fractions. However, the separation efficiency for small organic ions should be understood in detail. In this article, the membrane selectivity and transport mechanism of small organic ions from mixed salts by ion-exchange membranes are theoretically and experimentally investigated. First of all, the influence of current density on the solute flux (organic ions and inorganic ions) and on membrane selectivity (between organic ions and inorganic ions and between different organic ions) in ED has been studied. The selectivity was shown to be influenced by changing the applied current density. It was observed that separation of inorganic ions from organic solutes was feasible, but the selectivity was dependent on the size, charge, and functional groups of the organic ions. Furthermore, results imply that binary organic anions with larger molar mass ([130, i.e., aspartate and tartrate) can be adsorbed onto the membrane free volume and hence form a charged double layer, which affects membrane selectivity. Finally, competition between small organic and inorganic ions is discussed by comparison of the concentration profiles and current efficiencies of the different anions.

Electrodialysis potential for fractionation of multicomponent aqueous solutions

“…Similar results were found by Kabsch-Korbutowicz et al [9] -the ED process with monoselective anion-exchange membranes enabled better regeneration of spent brines contaminated by NOM, than standard ED. Detailed investigation of electrodialytic fractionation of small organic ions from mineral salts revealed that the process efficiency was influenced by current density, organic ion size and charge, as well as by the type of functional groups fixed to organic particles [10]. It is interesting to note that the big organic ions (of molecular weight above 130 kDa) can be deposited at the membrane surface, thus creating an additional bipolar layer and alternating the membrane selectivity.…”

Eliminación de As (V) y producción simultánea de polvo de cobre de un electrolito de Cu(II) - As(V) - H₂SO₄ mediante electrodiálisis reactiva

“…Los procesos de electro diálisis presentan un amplio espectro de aplicación desde la industria de alimentos, de reciclaje hasta la generación de energía [9][10][11][12][13][14][15][16][17] . Estos procesos se basan en el transporte másico selectivo de iones a través de membranas de intercambio iónico bajo la acción de un campo eléc-trico externo.…”

Nutrient recovery from wastewater using electrodialysis

“…Their work builds from Zhang et al (2012) in which a 'selectrodialysis' process is innovated with the specific purpose of separating monovalent and multivalent anions, as well as Zhang et al (2011b) in which the separation of small organic ions from salts was investigated.…”

“…Their study also identified that osmosis and electro-osmosis can limit the concentration of nutrients in the product. Zhang et al (2011b) demonstrated that it is possible to neglect these effects in relatively low concentration processes using synthetic wastewater.…”

“…Zhang et al (2011a) and Zhang et al (2011b) found that small charged anionic organic compounds have: a higher rate of transport through AEMs; a lower rate of fouling than larger anionic charged organic compounds; are more difficult to be separated from inorganic anions. From their work on anionic separation Zhang et al (2012b) recommended that further work is necessary to successfully fractionate different inorganic and/or organic ions or small charged particles on the basis of size, hydrophilicity or other characteristics.…”