Separation of La and Ce with PC-88A by counter-current mixer-settler extraction column

The separation of La and Ce with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (commercially known as PC-88A) from nitrate media was studied with a multistage counter-current mixer-settler extraction column of seven stages developed by the authors. The effect of flow rate ratio of the aqueous phase (Q(w)) to the organic phase (Q(o)) on the separation was studied. The maximum separation was obtained at Q(w)/Q(o) = 3.2 and the separation degree was 63. Scrubbing of the organic phase was also studied in order to enhance the separation. La was scrubbed from the organic phase with nitric acid at pH 2.7 and the separation degree during scrubbing was 45. Simulations of the extraction and scrubbing processes were carried out and compared with the obtained experimental results. Stripping of Ce was achieved by using 100 mol/m(3) nitric acid. The organic phase was successfully recycled during the experiments without any effect on the extraction efficiency. (C) 2002 Elsevier Science B.V. All rights reserved.