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4. Remarkable Improvement in Am3+ and Cm3+ Separation Using a Cooperative Counter Selectivity Strategy by a Combination of Branched Diglycolamides and Hydrophilic Polyaza-heterocycles

Author

Gujar, Rajesh B., primary, Kanekar, Avinash S., additional, Bhattacharyya, Arunasis, additional, Karthikeyan, Natesan S., additional, Ravichandran, Cingaram, additional, Toleti, Subba Rao, additional, Egberink, Richard J. M., additional, Huskens, Jurriaan, additional, Verboom, Willem, additional, and Mohapatra, Prasanta K., additional

Published
2024
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9. Understanding the Role of Ligand Structure on Extraction of Neptunium by N-Pivot Tripodal Diglycolamides in an Ionic Liquid.

Author

Gujar, Rajesh B., Ansari, Seraj A., Mohapatra, Prasanta K., and Verboom, Willem

Subjects
*METHYL groups, *LIGANDS (Chemistry), *ALKYL group, *IONIC liquids, *NEPTUNIUM
Abstract

The extraction of Np4+ was studied by a series of N-pivot tripodal diglycolamides, with varying substituents (alkyl groups with varying branching and chain length) and varying spacer length, dissolved in an ionic liquid, i.e. [C4mim][Tf2N]. Out of a series of four ligands, LI (propylene spacer) and LII (ethylene spacer) differ only in the spacer length connecting the three diglycolamide units with the tripodal N platform. While LII – LIV have the same spacer length (ethylene spacer), but LII has a hydrogen atom, LIII has methyl group, and LIV has isopropyl group as a substituent at the amidic N atom close to the central N atom. A reversal extraction mechanism of Np4+ was observed when the spacer chain length reduced from a propylene group in LI to an ethylene group in LII – LIV. While a cation-exchange mechanism was observed in case of LI, a solvation extraction mechanism was seen for the other three ligands with the extracted species being Np(NO3)2(L)2+ for LI, and [Np(NO3)4·L] for LII – LIV. The extraction efficiencies of Np4+ with LII – LIV were significantly affected by the nature of the alkyl substituents and follow the order: LII > LIII > LIV. This trend in the extraction pattern affirms that the alkyl substitution at the amidic N atom creates steric strain in the ligand while complexing with the metal ion. [ABSTRACT FROM AUTHOR]

Published
2024
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22. First Report on a 1-Cycle Solid-Phase Extraction Method for Selective Separation of Am3+and Eu3+: Use of BTP-Grafted Silica Decorated on Activated Carbon

Author

Ansari, Seraj A., Gujar, Rajesh B., Bhattacharyya, Arunasis, Thangaraj, Bharathkumar, Natesan Sundaramurthy, Karthikeyan, Ravichandran, Cingaram, Toleti, Subba Rao, and Mohapatra, Prasanta K.

Abstract

A new composite sorbent material was prepared by grafting bis-triazinylpyridine (BTP) onto silica and then blending it with activated charcoal (AC–Si–BTP) for the selective separation of Am3+over Eu3+using a 1-cycle solid-phase extraction for the direct separation of lanthanides from actinides. BTP was attached to silica via a sulfonamide bond between R–BTP and amino silane, and the resulting Si–BTP was covalently bonded to activated carbon (AC) with a favorable orientation of the ligand coordination sites. The material exhibited a significantly large distribution coefficient for Am3+over Eu3+at lower acidities (<0.5 M HNO3), and the separation factor between the two metal ions was found to be maximum in 0.2 M HNO3with a value of 110. The loading capacity of the material was 4.05 ± 0.12 mg of Eu per gram of the composite when investigated at pH 3. The radiation stability of the material was excellent when studied up to an absorbed dose of 1000 kGy. The material was tested for the separation of Am3+and Eu3+in a column mode, which gave selective loading of Am3+over Eu3+. The reusability studies indicated slow leaching of the BTP fraction from the solid, with a resultant decrease of the Kdvalues with time. To address this issue, the material was embedded in polysulfone beads for a separate set of studies, but the separation efficiencies were found to be comparable.

Published
2024
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39. Remarkable Improvement in Am3+and Cm3+Separation Using a Cooperative Counter Selectivity Strategy by a Combination of Branched Diglycolamides and Hydrophilic Polyaza-heterocycles

Author

Gujar, Rajesh B., Kanekar, Avinash S., Bhattacharyya, Arunasis, Karthikeyan, Natesan S., Ravichandran, Cingaram, Toleti, Subba Rao, Egberink, Richard J. M., Huskens, Jurriaan, Verboom, Willem, and Mohapatra, Prasanta K.

Abstract

Separation of Am3+and Cm3+is one of the most challenging problems in the back-end of the nuclear fuel cycle. In the present work, we exploited the cooperative effect of the opposite selectivity of hydrophobic branched DGA derivatives and hydrophobic N-donor heterocyclic ligands taken in two different phases to achieve improved separation behavior. A systematic study was performed using a series of DGA derivatives to understand the effect and the position of branching in the alkyl chains on the separation behavior of Am3+and Cm3+. A separation factor (S.F.) value as high as 10 for Cm3+over Am3+was obtained in the case of TiBDGA (N,N,N′,N′-tetra-iso-butyl diglycolamide) using SO3PhBTPhen ((phenanthroline-2,9-diyl)-1,2,4-triazine-5,5,6,6-tetrayltetrabenzenesulfonic acid) as the aqueous complexant, which is the highest reported value so far for the ligand-based separation of Am3+and Cm3+without involving any oxidation or reduction step. The high selectivity favoring Cm3+ion extraction in the case of this DGA derivative is also explained with the help of computational studies.

Published
2024
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40. Comparative evaluation of extraction of tetra- and hexa-valent neptunium ions by CMPO in a room temperature ionic liquid.

Author

Gujar, Rajesh B., Verma, Parveen K., Mahanty, Bholanath, Ansari, Seraj A., Goswami, Dibakar, and Mohapatra, Prasanta K.

Subjects
*IONIC liquids, *SULFONYL compounds, *TETRAFLUOROBORATES, *NEPTUNIUM, *SOLVENT extraction, *METHYL ether, *PHOSPHINE oxides, *TRIMETHYLAMINE oxide
Abstract

Solvent extraction studies were performed to understand the extraction behavior of Np4+ and NpO22+ from acidic feeds with CMPO (octyl (phenyl)-N,N-diisobutyl carbamoyl methyl phosphine oxide) dissolved in 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide, a water immiscible ionic liquid. Slope analyses on the distribution data revealed the extraction of ML2 type species, where M = Np4+ or NpO22+, and L = CMPO. Studies were also carried out with Pu4+ and UO22+ under identical conditions. The nature of the extracted species was found to vary with the nature of the ionic species. [ABSTRACT FROM AUTHOR]

Published
2020
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44. Sequestration of Np(IV) and Pu(IV) with Hexa-n-octyl nitrilotriacetamide (HONTA) in an Ionic Liquid: Unusual Species vis-à-visa Molecular Diluent

Author

Gujar, Rajesh B., Mahanty, Bholanath, Ansari, Seraj A., Egberink, Richard J. M., Huskens, Jurriaan, Verboom, Willem, and Mohapatra, Prasanta K.

Abstract

The extraction of Np(IV) and Pu(IV) was studied using a tripodal amide ligand (N,N,N′,N′,N″,N″-hexa-n-octyl nitrilotriacetamide termed as HONTA) in an ionic liquid (C4mim·NTf2) as well as in a molecular diluent mixture (95% n-dodecane +5% iso-decanol) from an aqueous feed containing diluted nitric acid. The extraction efficiency of Pu(IV) was higher than that of Np(IV), while the RTIL-based solvent system extracted the metal ions better than the molecular diluent-based solvent system. The extracted species were ascertained by slope analysis as M(NO3)5·L(LH) and M(NO3)4·L2for the ionic liquid- and the molecular diluent-based solvent systems, respectively. The stripping of the metal ions from the organic extracts was achieved efficiently when a buffered complexing medium of 0.05 M EDTA and 1 M guanidine carbonate was used. Cyclic voltammetry was done for the Np(IV) extract in the ionic liquid-based solvent system in view of the wide electrochemical window experienced.

Published
2023
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45. Remarkable Improvement in Am 3+ and Cm 3+ Separation Using a Cooperative Counter Selectivity Strategy by a Combination of Branched Diglycolamides and Hydrophilic Polyaza-heterocycles.

Author

Gujar RB, Kanekar AS, Bhattacharyya A, Karthikeyan NS, Ravichandran C, Toleti SR, Egberink RJM, Huskens J, Verboom W, and Mohapatra PK

Abstract

Separation of Am 3+ and Cm 3+ is one of the most challenging problems in the back-end of the nuclear fuel cycle. In the present work, we exploited the cooperative effect of the opposite selectivity of hydrophobic branched DGA derivatives and hydrophobic N-donor heterocyclic ligands taken in two different phases to achieve improved separation behavior. A systematic study was performed using a series of DGA derivatives to understand the effect and the position of branching in the alkyl chains on the separation behavior of Am 3+ and Cm 3+ . A separation factor (S.F.) value as high as 10 for Cm 3+ over Am 3+ was obtained in the case of TiBDGA ( N,N,N ', N '-tetra- iso -butyl diglycolamide) using SO 3 PhBTPhen ((phenanthroline-2,9-diyl)-1,2,4-triazine-5,5,6,6-tetrayltetrabenzenesulfonic acid) as the aqueous complexant, which is the highest reported value so far for the ligand-based separation of Am 3+ and Cm 3+ without involving any oxidation or reduction step. The high selectivity favoring Cm 3+ ion extraction in the case of this DGA derivative is also explained with the help of computational studies.

Published
2024
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