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

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 other substances.