The behaviour of selected elements on the cation exchange resin DOWEX 50W-X4 IN nitric acid medium

Abstract

Ion exchange chromatography is an important technique for the separation and isolation of elemental ions in a solution. Studying the distribution coefficients of individual elements provides important information regarding the separation and isolation of the element from a matrix. This study was carried out to determine the distribution coefficient for the selected monovalent elements: Li, Na, K, Rb and Ag; divalent elements: Mg, Ca, Ba Sr, Zn, Cu, Co, Mn, Cd and Pb; together with Al(III) and Fe(III). The strong acid cation exchange resin, Dowex 50W-X4, was used to determine the distribution coefficients of the elements in various nitric acid concentrations using the batch method. The distribution coefficients of individual elements provide vital information for possible separation and isolation of the elements from the matrix, and from each other. Concentrated HCl (5.0 M) is strong enough to elute the elements from the resin. The solution containing the cation exchange resin and the specific element, in the appropriate nitric acid concentration (0.1 M, 0.2 M, 0.5 M, 1.0 M, 2.0 M, 3.0 M, or 4.0 M) was shaken for 24 hours at 25 ºC. The phases were separated, and the concentration of the element determined by ICP-OES. The distribution coefficient for the element was then calculated from the values obtained. The distribution coefficients of the elements studied on DOWEX 50W-X4 were compatible with the distribution coefficients of the elements on AG50W-X8.