Lecture: 'Separating minor actinides from lanthanides: solution phase versus immobilized ligand - the importance of speciation'

Separation of the minor actinides, neptunium, americium and curium from the chemically very similar lanthanides and other fission products is a key step in the partitioning and transmutation scenario for reprocessing spent nuclear fuel. This has been achieved using nitrogen-bearing ligands, such as the bistriazinyl-phenanthroline (BTPhen) ligands that form 2 : 1 ligand : metal complexes. Modulation of electronic effects by substituting at the 5 and 5,6-position of BTPhen ligands has enabled these ligands to be fine-tuned in order to enhance the selectivity, not only for Am³⁺ over Eu³⁺, but also permits differentiation between the adjacent minor actinides americium and curium. Iron oxide nanoparticles (MNPs) have a large surface area and magnetic properties, meaning they can be extracted from aqueous dispersions. Modification of the MNPs with a coating of silica provides a means of immobilizing the ligands, but forces formation of 1 : 1 complexes with M³⁺ resulting in a totallydifferent selectivity for actinides over lanthanides that is dependent upon the concentration of NO₃^–.

About

Professor of Organic Chemistry at the University of Reading and Director of Chemical Analysis Facility, Laurence M Harwood obtained his PhD from the University of Manchester in 1975. His research expertise covers natural product total synthesis, synthetic methodology, pericyclic reactions, chiral morpholinones, amino acids, peptides, minor actinide-selective ligands and metal selective ligands. He is Synlett, Associate Editor for Europe and Countries excluding the Americas and the Far East since 2001 and, Editor-in-Chief of SynOpen since 2017.He has 170 refereed research publications, 10 patents, 9 review chapters and 4 books.