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Séminaire Chimie ED459

Hybrid materials for selective actinide and lanthanide separations

Dr. Jessica Veliscek-Carolan (Nuclear Fuel Cycle Research, ANSTO Australian Nuclear Science and Technology Organisation, Australia)

publié le

Le Jeudi 22 juin 2017 à 13h45
UM FdS, salle SC-16.01

Selective separation of actinides and other radioisotopes from complex media is a highly important challenge in the context of environmental remediation, mining and industrial processing. In terms of the nuclear fuel cycle, separation processes to recycle actinide elements that can be re-used as fuel are critical to increase the sustainability of nuclear technology and to decrease the hazards of nuclear waste. Currently, most actinide separation processes are performed via solvent extraction. However, use of solid sorbent materials has several advantages such as the lack of organic solvent wastes.

Framework materials based on titania and zirconia have been developed and functionalised with organic ligands in order to impart selectivity. Titania and zirconia based framework materials were chosen due to their radiolytic and hydrolytic stability, which should enable them to withstand the conditions required for separations in a nuclear context. Further, these materials may be used as transmutation matrices or wasteforms once they are loaded with actinides. Framework materials with high surface area and ordered porosity were developed in order to impart high sorption capacity and fast sorption kinetics. For example, a zirconium organophosphonate material has been developed that can selectively sorb 80 mg/g europium within 10 minutes. Also, ordered mesoporous titania powders and beads have been produced using the block copolymer F127 as a template without the use of stabilizing additives for the first time. The bead morphology is more practical than powder as it allows close packing in chromatographic columns with minimal clogging and high ease of handling.

In terms of organic ligands to impart selectivity, functionalities including phosphonate, amine, peptides or bistriazinylpyridine (BTP) have been incorporated. Both co‑condensation and post-synthetic covalent grafting were investigated as methods for functionalization of the porous inorganic framework materials. Using phosphonates or peptide functional groups, selectivity for lanthanides was demonstrated, while an amine functional groups demonstrated selectivity for uranium. Using BTP functionalized materials, the more challenging minor actinide-lanthanide separation could also be achieved.

Contact local ICSM : Dr. Jérémy Causse, chercheur CEA

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