Sahu S K, Chakravortty V, Reddy M L, Ramamohan T R
Department of Chemistry, Utkal University, Bhubaneswar 751 004, India.
Talanta. 2000 Mar 6;51(3):523-30. doi: 10.1016/s0039-9140(99)00312-4.
The extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been studied using mixtures of 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and dicyclohexano-18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6 or benzo-15-crown-5. The results demonstrate that these metal ions are extracted into chloroform as Th(PBI)(4) and UO(2)(PBI)(2) with HPBI alone and as Th(PBI)(4) . CE and UO(2)(PBI)(2) . CE in the presence of crown ethers (CE). The equilibrium constants of the above species have been deduced by non-linear regression analysis. The addition of a CE to the metal chelate system enhances the extraction efficiency and also improves the selectivities between thorium and uranium. IR spectral data of the extracted complexes were used to further clarify the nature of the complexes. The binding to the CEs by Th(PBI)(4) and UO(2)(PBI)(2) follows the CE basicity sequence but with DC18C6 and DB18C6, steric effects become more important.
利用3-苯基-4-苯甲酰基-5-异恶唑酮（HPBI）与二环己基-18-冠-6、苯并-18-冠-6、二苯并-18-冠-6或苯并-15-冠-5的混合物，研究了从硝酸溶液中萃取钍（IV）和铀（VI）的过程。结果表明，这些金属离子单独与HPBI时以Th(PBI)₄和UO₂(PBI)₂的形式被萃取到氯仿中，在冠醚（CE）存在下则以Th(PBI)₄·CE和UO₂(PBI)₂·CE的形式被萃取。通过非线性回归分析推导了上述物种的平衡常数。向金属螯合物体系中添加冠醚提高了萃取效率，同时也改善了钍和铀之间的选择性。利用萃取配合物的红外光谱数据进一步阐明了配合物的性质。Th(PBI)₄和UO₂(PBI)₂与冠醚的结合遵循冠醚碱性顺序，但对于二环己基-18-冠-6和二苯并-18-冠-6，空间效应变得更为重要。
