Detemination of Distribution Coefficients of Iron and Rare Earth Elements on DOWEX 1-X8 Anion Exchange Resin and Its Application to ICP-AES Determination of Rare Earth Elements in Steel

The distribution coefficients (Kd) of Fe3+ ion and ions of rare earth elements on DOWEX 1-X8 anion exchange resin in hydrochloric acid or nitric acid solutions of different acidites were studied.It was found that in 6-9 mol·L-1 hydrochloric acid,the Kd of Fe3+ was more than 103,while the Kd of rare earth elements were equal to or less than 10,hence,Fe3+ was adsorbed strongly on the resin,and ions of rare earth elements were not.The Kd of Fe3+ was less than 6.4 in nitric acid solution of concentration less than 2 mol·L-1,so Fe3+ was eluted from resin with 1.6 mol·L-1 nitric acid as eluent.Based on these facts,a method for separation of rare earth elements from matrix of iron was proposed and applied to the ICP-AES determination of rare earth elements in clean steels.Samples of clean steel produced in Japan and Korea were analyzed by the proposed method,giving values of recovery in the range of 87.7%-118.3%,and values of RSD′s (n=6) less than 23%.