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Application of Liquid Membrane Technology at Back End of Nuclear Fuel Cycle—Perspective and Challenges
Published in Anil K. Pabby, S. Ranil Wickramasinghe, Kamalesh K. Sirkar, Ana-Maria Sastre, Hollow Fiber Membrane Contactors, 2020
S. Panja, P. S. Dhami, J. S. Yadav, C. P. Kaushik
Bhattacharyya et al. [42] studied Cyanex-301 as carrier molecule in polypropylene (PP) hollow fiber-based supported liquid membrane for separation of trivalent actinides, viz. Am3+ and lanthanides, viz. La3+, Eu3+, Tb3+, Ho3+, Yb3+, and Lu3+. They observed much faster transport rates of Am3+ as compared to those of the trivalent lanthanide ions investigated in the study with the transport rates being affected by the concentration of Cyanex-301. Positive results with respect to high decontamination factors (DF) as well as throughputs suggested that this method may be applied for real waste solutions. They further studied [43] the effect of various neutral auxiliary donor ligands, viz. tri-n-butyl phosphate (TBP), N,N,-dihexyl octanamide (DHOA) and 2,20 -bipyridyl (Bipy) as synergists on the selective recovery of Am(III) over lanthanides. The presence of synergists showed the possibility of Am(III) recovery at lower pH values with improved separation factors. At pH 2, the separation factor value for different synergists followed the order: bipyridyl (350) > DHOA (50) > TBP (8). They also investigated the possibility of applying an aqueous soluble actinide selective ligand phenyl sulphonic acid functionalized bis-triazinyl pyridine (SO3-Ph-BTP) [44] using a TODGA-based HFSLM technique for separation of Am3+ from Eu3+. They showed that selective transport of Eu3+ from a mixture of Am3+ and Eu3+ using TODGA as the carrier from a feed solution of 1M HNO3 containing 10 mM ofSO3-Ph-BTP was possible with a DF > 100.
Solvent extraction systems for mutual separation of Am(III) and Cm(III) from nitric acid solutions. A review of recent state-of-the-art
Published in Solvent Extraction and Ion Exchange, 2021
Petr Matveev, Prasanta K. Mohapatra, Stepan N. Kalmykov, Vladimir Petrov
The water-soluble derivative of bis-triazinyl pyridine, 2,6-bis(5,6-di(sulphophenyl)-1,2,4-triazine-3-yl)pyridine (SO3-Ph-BTP, Figure 8a), was previously proposed for the selective extraction of actinides(III) in an i-SANEX[96] and EURO-GANEX[97] processes. In these processes, actinides were first co-extracted with the REEs by TODGA with subsequent selective stripping of actinides with the water-soluble ligand solution. However, application of aqueous solution of the SO3-Ph-BTP doesn’t allow separation of americium and curium – distribution ratios of Am(III) and Cm(III) are practically equal.
The influence of polarity in binary solvent mixtures on the conformation of bis-triazinyl-pyridine in solution
Published in Molecular Physics, 2018
Michael Trumm, Christian Adam, Carsten Koke, Martin Maiwald, Sebastian Höfener, Andrej Skerencak-Frech, Petra J. Panak, Bernd Schimmelpfennig
Molecular dynamics (MD) simulations allow the explicit description of thousands of solvent molecules, thus granting access to the investigation of solvent-, temperature- and dynamic effects. With water being the most common solvent, most research has been focussed on it and its mixtures with other solvents. Within the variety of organic solvents, we have chosen methanol as it is fully miscible with water, thus allowing titration experiments to be compared to the simulations. As a more unpolar solvent, chloroform was also considered as a solvent to highlight differences due to the lacking hydrogen bond network. There have been many successful experimental and theoretical studies on water and methanol wherein solvent models were able to reproduce measured properties like density, radial distribution functions or heat of vaporisation among others [1–7]. For solutes with different conformations, it is desirable to understand whether solvent effects originate from the solvent molecules or an induced conformation change. As a probe-system, we chose the actinide-selective bis-triazinyl-pyridine (BTP) ligand (Figure 1) which can be used to separate trivalent actinide ions from trivalent lanthanide ions in the SANEX process (see [8] and references therein) by liquid–liquid extraction. By torsion of the two triazine rings around the connecting C-C bond, three different conformations can be formed. Our study explains why the conformation of the ligand changes with changing solvent, which is of particular interest for BTP, as the conformation at the liquid/liquid interface is not entirely clear, but important for the kinetics of the An(III)/Ln(III) complex formation and subsequent extraction into the organic phase. We show that a study on the molecular level provides explanations and new insights on spectroscopic changes that cannot be deduced using experimental methods only.