AN IMPROVED ACTINIDE SEPARATION METHOD FOR ENVIRONMENTAL-SAMPLES

This paper presents a rapid method of separation of five actinide elem ents (Th, U, Np, Pu, and Am) for aqueous media samples. This separatio n method utilizes the unique chemistries of the actinides at low conce ntrations(1,2) and the properties of the ElChroM TRU-Resin(TM) extract ion resin. In order to cleanly recover the five actinides from aqueous samples or solubilized soil samples, the sample is passed through the column twice. The sample is first loaded in an HCl solution with hydr ogen peroxide. This allows the Am and most matrix ions to pass through the column. Then the Th is eluted using dilute HCl followed by the Np and Pu which are eluted together with oxalic acid in dilute HCl solut ion. Finally, the U is eluted with ammonium oxalate solution. A calciu m-oxalate coprecipitation is performed on the original load solution c ontaining the Am ions and the dissolved precipitate is then reloaded o nto the TRU-Resin(TM) column in HNO3 with ascorbic acid. The procedure requires approximately 1.5 working days for experienced technicians, greatly reduces waste, and generally results in actinide recoveries of 80-100%.