Ion exchange on resins with temperature-responsive selectivity: II. Thermo-induced concentration waves in ion-exchange column

This paper represents a critical review of the applicability of different ion-exchange purification techniques for manufacture of high purity inorganic, organic and biological substances. The review considers both traditional ion-exchange purification methods, such as frontal separation, reverse frontal separation and displacement chromatography, and relatively new ion-exchange fractionation techniques based upon governing the separation process by the modulation of temperature, ionic strength, and some other thermodynamic parameters known to shift the equilibrium in an ion-exchange system to the desired direction. A special attention is payed to the reagentless purification methods, which allow for designing ecologically clean ion-exchange technologies in applying both fixed bed and counter-current modes of operation. The paper comprises numerous examples on ion-exchange ultra purification of rare alkali metals, rare earth metals, freons, liquid crystalline substances, amino acids, DNA, and othe...

Ion-exchange methods for ultra purification of inorganic, organic and biological substances

The paper describes the new phenomenon called Ion-Exchange Isothermal Supersaturahon (IXISS). This effect is observed for a number of ion-exchange systems, where frontal or reverse frontal separation is accompanied by the formation of stable supersaturated solutions of slightly soluble substances in the interstitial space of ion-exchange columns. After leaving the column a supersaturated solution crystallizes spontaneously, which allows for designing practically ideal ion-exchange process where a crystalline product is obtained right after the ion-exchange purification cycle. The paper comprises results on experimental investigation of IXISS of amino acids (e.g., such as glutamic, aspartic and some others), calcium and magnesium salts (sulfates and carbonates), and some other substances. The mechanisms of stabilization of supersaturated amino acid solutions in the interstitial space is proposed and confirmed experimentally. Methods for identification of substances exhibiting the IXISS effect and ...

Ion-Exchange Isothermal Supersaturation

The evolution of ion exchange processes for separation and purification of substances by use of the influence of temperature both on the equilibrium and the dynamic properties of some ion exchange resins is discussed. Significant improvement of some ion exchange separations, diminishing of reagents consumption and waste quantities is achieved. In the same way, environmentally non-hazardous reagentless ion exchange methods of divalent and monovalent ionic mixtures separation are developed. This report is based on experimental studies of the equilibrium, dynamic and some other properties of ion exchange resins.

The role of temperature in ion exchange processes of separation and purification

This paper reviews the results obtained by studying the dual-temperature ion-exchange fractionation (DTIXF) technique. The DTIXF is based on the use of different affinity at different temperatures of ion exchangers towards ions to be separated. This technique allows to design absolutely reagentless and, as a result, wasteless fractionation technology. The review considers the temperature dependencies of selectivity of commercially available ion-exchange (LX) resins towards components of ionic mixtures of different complexity starting from binary model systems up to naturally existing nonacomponent effluents. A novel approach for predicting the temperature sensitivity of a given LX system is presented and discussed. The same approach has been shown to be applicable for the design of IX resins with temperature-dependent selectivity. The paper also reports the results obtained in the practical application of DTIXF technique for concentration of magnesium from seawater and copper from acidic mine wat...

Dual-temperature ion exchange fractionation

The term “parametric pumping” implies the idea of pumping, that is of transport of material (in our case, ionic species) up along some potential scale (in our case, chemical potential), at the cost of degradation of some flux of energy (to be specified later). The term “parametric” refers to the fact that the energy flux just mentionned is obtained by modulating some intensive thermodynamic parameter such as temperature, pressure, ionic strength, pH, electric potential, … Typical examples are temperature-swing ion-exchange and pressure-swing adsorption. The concept of parametric pumping is due to Wilhelm and coworkers (1966, 1968). Their original results deal with adsorption from the liquid phase, modulated by temperature. Let us examine how these phenomena are implemented.

G. Grevillot

Papers

Parametric Ion-Exchange Processes (Parametric Pumping and Allied Techniques)