Studies on the selectivity of di-triazinyl-pyridines: EXAFS, TRLFS, and quantum-chemical calculations

Methods and technologies for separating those radionuclides (i.e., plutonium, neptunium, americium and curium) responsible for long-term radiotoxicity of spent nuclear fuel are being explored within the European research project, EUROPART. A key step is the separation of trivalent americium and curium from the chemically similar lanthanides. Di(5,6-dialkyl-1,2,4-triazin-3-yl)pyridines (BTP) accomplish this task; however, their selectivity is not yet understood. A comparative investigation of americium, curium and europium complexed with BTP was made, showing that the high selectivity of BTP does not result from structural difference between the actinide and lanthanide complexes but is due to differences in the thermodynamic stabilities of the respective complexes. (orig.)