Separation of the minor actinides (Am/Cm) from spent nuclear fuel post-PUREX process is expected to play a key part in new reprocessing methodologies. To date, a number of selective americium extractants from the BTPhen ligand family have been identified. In this investigation, we synthesise 24 novel BTPhens with additional functionality to determine the effects on solubilities and americium extraction capabilities. The data obtained will allow for tuning of steric/electronic properties of BTPhens in order to assist future extractant design.

Extraction chromatography (EC) resins are widely used in analytical radiochemical separations, in particular for actinide separation. However, there is currently limited choice for separation of americium using EC, with DGA (N,N,N′,N′-tetra-n-octyldiglycolamide) resin being the preferred option. Here, we describe preparation and testing of a covalently-linked EC resin utilising a triazine soft N-donor (Me4BTPhen) extractant for americium extraction. The resin was generated by conjugation of a Me4BTPhen derivative with poly(vinylbenzyl) chloride to generate PVB–Me4BTPhen. PVB–Me4BTPhen was shown to extract americium from a complex matrix simulating nuclear forensic samples, and containing lanthanides, actinides and matrix elements with high Am (III) recovery (>90%) and low extraction of other elements, and provides an alternative to the currently used BTPhen liquid–liquid separation process for Am (III) extraction.

The redox chemistry of the actinide elements plays a central role in many aspects of nuclear fission technology including the reprocessing of spent fuel, safe disposal strategies and in the ability to reliably predict the mobility of actinides in natural and engineered environmental conditions. In both aqueous and non-aqueous conditions, the redox chemistry of the actinides can be complicated and diverse and speciation is governed by both the actinide in question and many environmental factors. Although, historically, actinyl(VI) and (V) ions have been the subject of the most in depth research, the study of actinide ions in the +IV oxidation state (principally for U, Np and Pu) is inherently important in governing speciation in all aspects of the nuclear fuel cycle. Importantly, reactions involving reduction, disproportionation and re-oxidation tend to involve actinide ions in the +IV oxidation state leading to complex systems particularly in aqueous solution that control the solubility and migratory behaviour of actinide containing species. In this review, we focus on recent developments in the coordination and redox chemistry of the actinides involving actinide(IV) species in terms of fundamental coordination chemical studies, mineral chemistry, biogeochemistry and the implications of hydrolysis chemistry on the chemical and physical behaviour of actinide(IV) ions in the natural and engineered environment.

Separation of the minor actinides (Am/Cm) from spent nuclear fuel post-PUREX process is expected to play a key part in new reprocessing methodologies. To date, a number of selective americium extractants from the BTPhen ligand family have been identified. In this investigation, we synthesise 24 novel BTPhens with additional functionality to determine the effects on solubilities and americium extraction capabilities. The data obtained will allow for tuning of steric/electronic properties of BTPhens in order to assist future extractant design.