Extraction and Separation of Some Naturally Occurring Radionuclides from Rare Earth Elements by Different Amines

Uranium (U), thorium (Th) and rare earth elements (REEs) are important elements not only in environmental concern but also in industrial applications. In this endeavor, new extraction and separation procedure for U and Th from REEs has been developed. The parameters affecting U and Th extraction using different amines such as contact time, ph of the aqueous phase and metal ion concentration as well as amines concentration in the organic phase were investigated. Comparison between the results of using three different amines (primary, secondary and tertiary amines) as organic extractants has been reported. It was observed that the primary amine (Octylamine) is more effective for extraction of U, Th and REEs rather than the other two amines. On the other hand, the secondary and tertiary amines are more selective for extraction of U and Th rather than REEs. In a single element system, the extraction of U and Th are preferably with Octylamine. The results indicated the possibility of extracting 90% of U by 0.1 mol/l Octylamine at ph 4 for 2 hrs at 25 degree C, while Th extraction efficiency reached faster to 97% by 0.005 mol/l Octylamine after 15 min., at ph 3 and 25 degree c. In multi elements system, the separation of U and Th from REEs was mainly carried out by tertiary amine. It was found that, 80% of Th could be efficiently separated by 0.01 M N,N-dimethyl aniline at ph 4 for 15 min., while 66% of U was then separated by 0.1 M N,N-dimethylaniline at pH 7 for 30 min., leaving REEs in the aqueous solution.