Results are presented of an interlaboratory round-robin study of the application of timeResolved Emission Spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media. This involved 13 independent laboratories, using various instrumental adevices and data 2 analysis methods. In some cases, experimental data from a laboratory were analysed using different softwares. Samples were prepared based on appropriate speciation diagrams and in general were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (i) acidic medium where UO 2 2+ aq is the single emitting species, (ii) uranyl in the presence of fluoride ions, (iii) uranyl in the presence of sulfate ions, and (iv) uranyl in aqueous solutions under various pH conditions, promoting hydrolysed species. Results between the laboratories are compared in terms of number of decay components, luminescence lifetimes and spectral band positions. The potentials and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.

Diglycolamide extractants, and in particular N,N,N’N’- tetraoctyl diglycolamide (TODGA), are currently under investigation for use in nuclear fuel reprocessing by liquid-liquid separations. Several processes, such as ARTIST, i-Sanex, and EURO-GANEX...

Separation processes based on room temperature ionic liquids (RTIL) and electrochemical refining are promising strategies for the recoveryo fl anthanides from primary ores and electronic waste. However,t hey require the speciation of dissolved elements to be knownw ith accuracy. In the present study,E uc oordination and Eu III /Eu II electrochemical behavior as af unction of water contenti n1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm] [NTf 2 ]) was investigatedu sing UV-visible spectrophotometry, time-resolvedl aser fluorescence spectroscopy,e lectrochemistry,a nd X-ray absorption spectroscopy. In situ measurements were performed in spectroelectrochemicalc ells. Undera nhydrous conditions, Eu III and Eu II were complexed by NTf 2 ,f orming EuÀOa nd EuÀ(N,O) bonds with the anion sulfoxide functiona nd Na toms, respectively.T his complexation resulted in agreater stabilityofEu II ,and in quasi-reversible oxidation-reduction with an E 0 'p otential of 0.18 V versust he ferrocenium/ferrocene (Fc + /Fc) couple. Upon increasingw ater content,p rogressivei ncorporation of water in the Eu III coordination sphereo ccurred. This led to reversible oxidation-reduction reactions, but also to ad ecreasei n stabilityo ft he + II oxidation state (E 0 ' = À0.45 Vv s. Fc + /Fc in RTIL containing 1300 mm water).

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In this work we report on the electrochemical behavior of Ce(IV)/Ce(III) redox couple in pure N,N‐dialkyl amides (N,N‐DA), namely N,N‐di(2‐ethylhexyl)‐n‐butanamide (DEHBA), N,N‐di(2‐ethylhexyl)‐iso‐butanamide (DEHiBA), and N,N‐di(2‐ethylhexyl)‐3,3‐dimethyl butanamide (DEHDMBA) equilibrated with nitric aqueous solutions as an entry to the direct electrochemical characterization of plutonium in these extractants. Ce(IV)/Ce(III) redox process was used as a model. Its potential (E1/2≅1.02 V/SCE) is not affected by the temperature and the nature of the N,N‐DA and this clearly indicates that the functionalities of these extractants produce the same relative effect on both +IV and +III oxidation states of the cerium cation. Linear variations of the current intensity of the reduction peak of Ce(IV) with the concentration of Ce(IV)/N,N‐DAs/HNO3(5 M) solutions were obtained from cyclic voltammograms recorded at 25 °C and 40 °C. Due to the poor definition of the voltammograms in DEHiBA and DEHDMBA, such characterization allows only the evaluation of the performances of the chemical extraction of Ce(IV) from aqueous nitric acid solution by the undiluted DEHBA. To our knowledge, the electrochemical behavior of Ce(IV)/Ce(III) in N,N‐DAs was not previously studied and our findings will for sure open the door for further investigations in this field.