Dual-temperature ion exchange fractionation

This paper reviews the results obtained by studying the dual-temperature io n-exchange fractionation (DTIXF) technique. The DTIXF is based on the use o f different affinity at different temperatures of ion exchangers towards io ns 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-e xchange (IX) resins towards components of ionic mixtures of different compl exity starting from binary model systems up to naturally existing nonacompo nent effluents. A novel approach for predicting the temperature sensitivity of a given IX system is presented and discussed. The same approach has bee n shown to be applicable for the design of IX resins with temperature-depen dent selectivity. The paper also reports the results obtained in the practi cal application of DTIXF technique for concentration of magnesium from seaw ater and copper from acidic mine waters. The flowsheets of DTIXF processes are proposed and discussed.