engleski

Isolation of uranium and thorium from natural samples

Uranium and thorium are the first members of natural radioactive chain which makes their determination in natural materials interesting from geochemical and radioecological aspect. They are quantitatively determined as elements by spectrophotometric method and/or their radioisotopes by alpha spectrometry. It is necessary to develop inexpensive, rapid and sensitive methods for the routine researches because of continuous monitoring of the radioactivity level. Development of a new method for the isolation of uranium and thorium from liquid samples and subsequent spectrophotometric determination will be described in this paper. It is possible to isolate uranium and thorium from drinking and seawater using extraction chromatography or ion exchange. Uranium and thorium can be strongly bound on the extraction chromatographic resins (TRU and/or UTEVA) from 3 mol dm-3 HNO3 (chemical recovery is 100%). From alcoholic solutions of nitric acid thorium can be strongly bound on the anion exchanger Amberlite CG-400 (NO3- form). Uranium is much more weakly bound on the anion exchanger which enables its separation from thorium. After the separation uranium and thorium are determined by spectrophotometric method with arsenazo III and thorin respectively. Developed method enables selection of the optimal mode of isolation for the given purposes.

thorium; uranium; extraction chromatography; ion exchange chromatography; spectrophotometry

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