Transition metal-free, visible-light mediated synthesis of 1,10-phenanthroline derived ligand systems

A broad range of 1,10-phenanthroline substrates was efficiently C-H functionalised, providing rapid, gram-scale access to substituted heteroaromatic cores of broad utility. Furthermore, this C-H functionalisation pathway was extended to the synthesis of previously inaccessible, ultra-soluble, 2,9-bis-triazinyl-1,10-phenanthroline (BTPhen) ligands for advanced nuclear fuel cycles

Highly efficient separation of actinides from lanthanides by a phenanthroline-derived bis-triazine ligand

The synthesis, lanthanide complexation, and solvent ex- traction of actinide(III) and lanthanide(III) radiotracers from nitric acid solutions by a phenanthroline-derived quadridentate bis-triazine ligand are described. The ligand separates Am(III) and Cm(III) from the lanthanides with remarkably high efficiency, high selectivity, and fast extraction kinetics compared to its 2,2'-bipyridine counterpart. Structures of the 1:2 bis-complexes of the ligand with Eu(III) and Yb(III) were elucidated by X-ray crystallography and force field calculations, respec-tively. The Eu(III) bis-complex is the first 1:2 bis-complex of a quadridentate bis-triazine ligand to be characterized by crystallography. The faster rates of extraction were verified by kinetics measurements using the rotating membrane cell technique in several diluents. The improved kinetics of metal ion extraction are related to the higher surface activity of the ligand at the phase interface. The improvement in the ligand's properties on replacing the bipyridine unit with a phenanthroline unit far exceeds what was anticipated based on ligand design alone

Exploring electronic effects on the partitioning of actinides(III) from lanthanides(III) using functionalised bis-triazinyl phenanthroline ligands

The first examples of 4,7-disubstituted 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzo-triazin-3-yl)-1,10- phenanthroline (CyMe4 -BTPhen) ligands are reported herein. Evaluating the kinetics, selectivity and stoichiometry of actinide(III) and lanthanide(III) radiotracer extractions has provided a mechanistic insight into the extraction process. For the first time, it has been demonstrated that metal ion extraction kinetics can be modulated by backbone functionalisation and a promising new CHON compliant candidate ligand with enhanced metal ion extraction kinetics has been identified. The effects of 4,7- functionalisation on the equilibrium metal ion distribution ratios are far more pronounced than those of 5,6-functionalisation. The complexation of Cm(III) with two of the functionalised ligands was investigated by TRLFS and, at equilibrium, species of 1:2 [M:L] stoichiometry were observed exclusively. A direct correlation between the ELUMO-EHOMO energy gap and metal ion extraction potential is reported, with DFT studies reaffirming experimental findings

Flow-sheet design for an innovative SANEX process using TODGA and SO3-Ph-BTP

An innovative SANEX process was designed using an organic phase comprising TODGA in TPH + 5% 1-octanol and an aqueous phase containing SO3-Ph-BTP for the selective strip. The flow-sheet was optimized using batch data, single stage data and data from previously run TODGA processes. Recoveries for some key elements were calculated for selective strip section of the process using the SX Process program. According to the calculations, the An(III) are recovered from the PUREX raffinate with insignificant amounts of impurities. The presented flow-sheet will be used for a centrifugal contactor demonstration process which is expected to be successful.JRC.E.5-Nuclear chemistr

Use of polyaminocarboxylic acids as hydrophilic masking agents for fission products in actinide partitioning processes

During the partitioning of trivalent actinides from High Active Raffinate (HAR) solutions most processes have to cope with an undesirable co-extraction of some of the fission products. Four hydrophilic complexing agents of the group of polyaminocarboxylic acids, namely EDTA, HEDTA, DTPA and CTDA were tested and compared for their ability to complex fission products in a simulated PUREX raffinate solution, thereby preventing their extraction into an organic solvent. Several solvents, based on TODGA and the DIAMEX reference molecule DMDOHEMA, that are commonly known to show quite high Zr and Pd co-extraction were studied. Our investigations ultimately resulted in a substitution of oxalic acid and HEDTA by cyclohexanediaminetetraacetic acid (CDTA). A small addition of this hydrophilic complexing agent to the feed decreased the distribution ratios of Zr from 100 to 90% of the metal retained in the feed solution. The extraction of trivalent actinides and lanthanides was not negatively affected by the presence of CDTA. Furthermore, experiments with high concentrations of Zr proved the applicability of this new masking agent. The suppression of Zr and Pd extraction was also verified at a high Pu loading which makes CDTA, as a masking agent, attractive for grouped actinide extraction processes (GANEX) as well as DIAMEX-SANEX type separations.JRC.E.5-Nuclear chemistr

Development and demonstration of a new SANEX Partitioning Process for selective actinide(III)/lanthanide(III) separation using a mixture of CyMe4BTBP and TODGA

Within the framework of the European collaborative project ACSEPT, a new SANEX partitioning process was developed at Forschungszentrum Jülich for the separation of the trivalent minor actinides americium, curium and californium from lanthanide fission products in spent nuclear fuels. The development is based on batch solvent extraction studies, single-centrifugal contactor tests and on flow-sheet design by computer code calculations. The used solvent is composed of 6,6´-bis(5,5,8,8-tetramethyl-5,6,7,8 tetrahydrobenzo-[1,2-4]trizazin-3-yl)-[2,2´]-bipyridine (CyMe4BTBP) and N,N,N´,N´-tetraoctyldiglycolamide (TODGA) dissolved in n-octanol. A spiked continuous counter-current test was carried out in miniature centrifugal contactors with the aid of a 20-stage flow sheet consisting of 12 extraction, 4 scrubbing and 4 stripping stages. A product fraction containing more than 99.9% of the trivalent actinides Am(III), Cm(III) and Cf(III) was obtained. High product/feed decontamination factors >1000 were achieved for these actinides. The trivalent lanthanides were directed to the raffinate of the process with the actinide (III) product stream being contaminated with less than 0.5 mass-% of the initial lanthanides.JRC.E.5-Nuclear chemistr