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Rajani P, Sachin AR, Nagarajan S, Brahmananda Rao CVS, Gopakumar G. Insights into the Coordination Behavior of Methyl-Substituted Phosphinic Acids with Actinides. Inorg Chem 2022; 61:13047-13057. [PMID: 35942987 DOI: 10.1021/acs.inorgchem.2c01287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic structure and complexation behavior of methyl-substituted phosphinic acids with U(VI) and Pu(IV) were explored by applying quantum chemical methods. In contrast to Ingold's classification, our results indicate that the methyl group is electron-withdrawing, reducing the phosphoryl group electron density in substituted phosphinic acids. The magnitude of the computed complexation energy values increases along with the series, PA → MPA → DMPA, and MP → MMP → MDMP, implying an increasing complexation tendency upon methyl group substitution for both U(VI) and Pu(IV) complexes. One of the nitrate groups in UO2(NO3)2•2L complexes (L = PA, MPA, and DMPA) is in monodentate coordination mode due to the additional stability gained from O2N-O···H hydrogen bonding interactions with the acidic H atoms of respective ligands. The calculation indicates marginally stronger metal-ligand interactions in Pu(IV) complexes compared to that in U(VI), which is supported by the computed complexation energies, M-OP bond lengths, ν(P═O), the extent of metal-ligand charge transfer, and properties of M-OP bond critical points. The energy landscape of substituted phosphinic acid ligands is further analyzed within the framework of the activation strain model to explain the energetic preference of certain conformers.
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Affiliation(s)
- Puchakayala Rajani
- Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603102, India.,Homi Bhabha National Institute, Training School Complex, Anushakthinagar, Mumbai 400094, India
| | - Aditya Ramesh Sachin
- Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603102, India.,Homi Bhabha National Institute, Training School Complex, Anushakthinagar, Mumbai 400094, India
| | - Sivaraman Nagarajan
- Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603102, India.,Homi Bhabha National Institute, Training School Complex, Anushakthinagar, Mumbai 400094, India
| | - Cherukuri Venkata Siva Brahmananda Rao
- Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603102, India.,Homi Bhabha National Institute, Training School Complex, Anushakthinagar, Mumbai 400094, India
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2
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Kumal RR, Wimalasiri PN, Servis MJ, Uysal A. Thiocyanate Ions Form Antiparallel Populations at the Concentrated Electrolyte/Charged Surfactant Interface. J Phys Chem Lett 2022; 13:5081-5087. [PMID: 35653184 DOI: 10.1021/acs.jpclett.2c00934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Anions play significant roles in the separation of lanthanides and actinides. The molecular-scale details of how these anions behave at aqueous interfaces are not well understood, especially at high ionic strengths. Here, we describe the interfacial structure of thiocyanate anions at a soft charged interface up to 5 M bulk concentration with combined classical and phase-sensitive vibrational sum frequency generation (PS-VSFG) spectroscopy and molecular dynamics (MD) simulations. At low concentrations thiocyanate ions are mostly oriented with their sulfur end pointing toward the charged surfactants. The VSFG signal reaches a plateau at around 100 mM bulk concentration, followed by significant changes above 1 M. At high concentrations a new thiocyanate population emerges with their sulfur end pointing toward the bulk liquid. The -CN stretch frequency is different for up and down oriented SCN- ions, indicating different coordination environments. These results provide key molecular-level insights for the interfacial behavior of complex anions in highly concentrated solutions.
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Affiliation(s)
- Raju R Kumal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Pubudu N Wimalasiri
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Michael J Servis
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Ahmet Uysal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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3
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Das A, Ali SM. Deciphering the curved profile of uranyl ions at the aqueous-organic interface by atomistic simulations. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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4
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Celis Barros C, Pilgrim CD, Cook AR, Mezyk SP, Grimes TS, Horne GP. Influence of uranyl complexation on the reaction kinetics of the dodecane radical cation with used nuclear fuel extraction ligands (TBP, DEHBA, and DEHiBA). Phys Chem Chem Phys 2021; 23:24589-24597. [PMID: 34710211 DOI: 10.1039/d1cp03797h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Specialized extractant ligands - such as tri-butyl phosphate (TBP), N,N-di-(2-ethylhexyl)butyramide (DEHBA), and N,N-di-2-ethylhexylisobutryamide (DEHiBA) - have been developed for the recovery of uranium from used nuclear fuel by reprocessing solvent extraction technologies. These ligands must function in the presence of an intense multi-component radiation field, and thus it is critical that their radiolytic behaviour be thoroughly evaluated. This is especially true for their metal complexes, where there is negligible information on the influence of complexation on radiolytic reactivity, despite the prevalence of metal complexes in used nuclear fuel reprocessing solvent systems. Here we present a kinetic investigation into the effect of uranyl (UO22+) complexation on the reaction kinetics of the dodecane radical cation (RH˙+) with TBP, DEHBA, and DEHiBA. Complexation had negligible effect on the reaction of RH˙+ with TBP, for which a second-order rate coefficient (k) of (1.3 ± 0.1) × 1010 M-1 s-1 was measured. For DEHBA and DEHiBA, UO22+ complexation afforded an increase in their respective rate coefficients: k(RH˙+ + [UO2(NO3)2(DEHBA)2]) = (2.5 ± 0.1) × 1010 M-1 s-1 and k(RH˙+ + [UO2(NO3)2(DEHiBA)2]) = (1.6 ± 0.1) × 1010 M-1 s-1. This enhancement with complexation is indicative of an alternative RH˙+ reaction pathway, which is more readily accessible for [UO2(NO3)2(DEHBA)2] as it exhibited a much larger kinetic enhancement than [UO2(NO3)2(DEHiBA)2], 2.6× vs. 1.4×, respectively. Complementary quantum mechanical calculations suggests that the difference in reaction kinetic enhancement between TBP and DEHBA/DEHiBA is attributed to a combination of reaction pathway (electron/hole transfer vs. proton transfer) energetics and electron density distribution, wherein attendant nitrate counter anions effectively 'shield' TBP from RH˙+ electron transfer processes.
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Affiliation(s)
- Cristian Celis Barros
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
| | - Corey D Pilgrim
- Center for Radiation Chemistry Research, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415, USA.
| | - Andrew R Cook
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York, 11973, USA
| | - Stephen P Mezyk
- Department of Chemistry and Biochemistry, California State University Long Beach, 1250 Bellflower Boulevard, Long Beach, California, 90840-9507, USA
| | - Travis S Grimes
- Center for Radiation Chemistry Research, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415, USA.
| | - Gregory P Horne
- Center for Radiation Chemistry Research, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID, 83415, USA.
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5
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Hydration of the pertechnetate anion. DFT study. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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6
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Sarkar S, Rajeswari S, Suresh A, Sivaraman N. Hydrodynamic Properties of Tris(2-methylbutyl) Phosphate and Tri-n-alkyl Phosphates in n-Dodecane – A Comparative Investigation between Unirradiated and Gamma Irradiated Solvent Systems. SOLVENT EXTRACTION AND ION EXCHANGE 2021. [DOI: 10.1080/07366299.2021.1972648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Subramee Sarkar
- Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, India
| | - S. Rajeswari
- Analytical Chemistry & Spectroscopy Division, IGCAR, Kalpakkam, India
| | - A. Suresh
- Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, India
| | - N. Sivaraman
- Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, India
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7
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Kumar N, Servis MJ, Clark AE. Uranyl Speciation in the Presence of Specific Ion Gradients at the Electrolyte/Organic Interface. SOLVENT EXTRACTION AND ION EXCHANGE 2021. [DOI: 10.1080/07366299.2021.1954323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Nitesh Kumar
- Department of Chemistry, Washington State University, Pullman, Washington, USA
| | - Michael J. Servis
- Department of Chemistry, Washington State University, Pullman, Washington, USA
| | - Aurora E. Clark
- Department of Chemistry, Washington State University, Pullman, Washington, USA
- Pacific Northwest National Laboratory, Richland, Washington, USA
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8
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Does uranyl-TBP complex formation happen at the aqueous-organic interface? Revelation by molecular dynamics simulations. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Zhu L, Lan Y, Liu Q, Hao X, Zhou J, Yang S. Speciation analysis the complexation of uranyl nitrate with tri- n-butyl phosphate in supercritical CO 2. RSC Adv 2021; 11:36391-36397. [PMID: 35494389 PMCID: PMC9043467 DOI: 10.1039/d1ra06512b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 10/26/2021] [Indexed: 11/21/2022] Open
Abstract
The complexation of solid uranyl nitrate with tri-n-butyl phosphate (TBP) in supercritical CO2 is quite different from that of a liquid–liquid extraction system because fewer water molecules are involved. Here, the complexation mechanism was investigated by molecular dynamics simulation, emphasising on speciation distribution analysis. In the anhydrous uranyl nitrate system, poly-core uranyl-TBP species [UO2(NO3)2]2·3TBP and [UO2(NO3)2]3·3TBP were formed in addition to the predominant [UO2(NO3)2]·1TBP and [UO2(NO3)2]·2TBP species. The poly-core species was mainly constructed via the linkage of U
Created by potrace 1.16, written by Peter Selinger 2001-2019
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O⋯U contributed by pre-developed [UO2(NO3)2]·1TBP species. However, in the hydrated uranyl nitrate system, TBP·[UO2(NO3)2]·H2O species form, preventing the formation of the poly-core species. The complexation developed differently depending on the TBP to the uranyl nitrate ratio, the solute densities and the participation of water. It suggested that the kinetically favoring species would gradually convert into the thermodynamically stable species [UO2(NO3)2]·2TBP by ligand exchange. Uranyl nitrate complex with TBP in supercritical CO2 could form 1 : 1 and 1 : 2 species, and further generate 2 : 3 and 3 : 3 poly-core uranyl species.![]()
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Affiliation(s)
- Liyang Zhu
- Department of Radiochemisty, China Institute of Atomic Energy, Beijing, 102413, China
| | - Youshi Lan
- Department of Radiochemisty, China Institute of Atomic Energy, Beijing, 102413, China
| | - Qian Liu
- Department of Radiochemisty, China Institute of Atomic Energy, Beijing, 102413, China
| | - Xuan Hao
- Department of Radiochemisty, China Institute of Atomic Energy, Beijing, 102413, China
| | - Jin Zhou
- Department of Radiochemisty, China Institute of Atomic Energy, Beijing, 102413, China
| | - Suliang Yang
- Department of Radiochemisty, China Institute of Atomic Energy, Beijing, 102413, China
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10
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Liu Z, Ren X, Tan R, Chai Z, Wang D. Key Factors Determining Efficiency of Liquid-Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe 4-BTPhen and Its Am(III) Complexes. J Phys Chem B 2020; 124:1751-1766. [PMID: 32039594 DOI: 10.1021/acs.jpcb.9b08447] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CyMe4-BTPhen (2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-1,10-phenanthroline, denoted as L) has been considered as a promising extractant in lanthanide(III)/actinide(III) separation. Vast endeavors in its application put forward a compelling need on the understanding of the underlying mechanism in the liquid-liquid extraction. To address the issue of its dynamics in biphasic systems, we carried out molecular dynamics (MD) simulations of L and its complexes with a heavy f-block metal ion, americium(III) (Am3+) in "oil"/water binary solvents. Two types of organic phases have been considered, differing in the presence of octanol in the bulk n-dodecane or not, and the distribution of the solutes and their interfacial behaviors have been investigated. Two of the key factors that determine the efficiency of a liquid-liquid extraction protocol were delineated and discussed, that is, the appropriate ligand to enhance the lipophilicity of AmL complexes and appropriate way to form ion pairs to minimize the attraction between the complexes and aqueous phase. The simulations showed that the charge states of both ligand and AmL complexes were strongly correlated with their phase behavior, and the migration of neutral species was driven by van der Waals interactions while that of charged species by electrostatic interactions, indicating stronger lipophilicity of the former than the latter. The presence of octanol facilitated the migration of the ligand from the interface to the organic phase via hydrogen bond between its polar head and the ligand or the AmL complexes and constituted a polar core in the organic phase. This work bridged the widely used liquid-liquid extraction technique in chemistry to a fundamental chemical concept, that is, minimization of hydrophilicity and maximization of lipophilicity to facilitate phase transfer from the aqueous phase to the organic phase, and is expected to improve the understanding of dynamics of ligands and their complexes with metal ions and to contribute to the development of efficient protocols for phase transfer of target species.
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Affiliation(s)
- Ziyi Liu
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xu Ren
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rongri Tan
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.,College of Communication and Electronics, Jiangxi Science & Technology Normal University, Nanchang 330013, China
| | - Zhifang Chai
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,State Key Laboratory of Radiation Medicine and Protection, and School of Radiation Medicine and Interdisciplinary Sciences (RAD-X), Soochow University, Suzhou 215123, China
| | - Dongqi Wang
- CAS Key Laboratory of Nuclear Radiation and Nuclear Techniques, Multidisciplinary Initiative Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Dwadasi BS, Goverapet Srinivasan S, Rai B. Interfacial structure in the liquid-liquid extraction of rare earth elements by phosphoric acid ligands: a molecular dynamics study. Phys Chem Chem Phys 2020; 22:4177-4192. [PMID: 32040116 DOI: 10.1039/c9cp05719f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Solvent extraction (SX), wherein two immiscible liquids, one containing the extractant molecules and the other containing the solute to be extracted are brought in contact to effect the phase transfer of the solute, underpins metal extraction and recovery processes. The interfacial region is of utmost importance in the SX process, since besides thermodynamics, the physical and chemical heterogeneity at the interface governs the kinetics of the process. Yet, a fundamental understanding of this heterogeneity and its implications for the extraction mechanism are currently lacking. We use molecular dynamics (MD) simulations to study the liquid-liquid interface under conditions relevant to the SX of Rare Earth Elements (REEs) by a phosphoric acid ligand. Simulations revealed that the extractant molecules and varying amounts of acid and metal ions partitioned to the interface. The presence of these species had a significant effect on the interfacial thickness, hydrogen bond life times and orientations of the water molecules at the interface. Deprotonation of the ligands was essential for the adsorption of the metal ions at the interface, with these ions forming a number of different complexes at the interface involving one to three extractant molecules and four to eight water molecules. Although the interface itself was rough, no obvious 'finger-like' water protrusions penetrating the organic phase were seen in our simulations. While the results of our work help us gain fundamental insights into the sequence of events leading to the formation of a variety of interfacial complexes, they also emphasize the need to carry out a more detailed atomic level study to understand the full mechanism of extraction of REEs from the aqueous to organic phases by phosphoric acid ligands.
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Affiliation(s)
- Balarama Sridhar Dwadasi
- TCS Research, Tata Research Development and Design Center, 54-B Hadapsar Industrial Estate, Hadapsar, Pune - 411013, Maharashtra, India.
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12
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Chandrasekar A, Ghanty TK, Brahmmananda Rao CVS, Sundararajan M, Sivaraman N. Strong influence of weak hydrogen bonding on actinide-phosphonate complexation: accurate predictions from DFT followed by experimental validation. Phys Chem Chem Phys 2019; 21:5566-5577. [PMID: 30785454 DOI: 10.1039/c9cp00479c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Among the varied classes of weak hydrogen bond, the CHO type is one of immense interest as it governs the finer structures of biological and chemical molecules, hence determining their functionalities. In the present work, this weak hydrogen bond has been shown to strongly influence the complexation behaviour of uranyl nitrate [UO2(NO3)2] with diamyl-H-phosphonate (DAHP) and its branched isomer disecamyl-H-phosphonate (DsAHP). The structures of the bare ligands and complexes have been optimized by density functional theory (DFT) calculations. Surprisingly, despite having the same chemical composition the branched UO2(NO3)2·2DsAHP complex shows a remarkably higher stability (by ∼14 kcal mol-1) compared to the UO2(NO3)2·2DAHP complex. Careful inspection of the optimized structures reveals the existence of multiple CHO hydrogen-bonding interactions between the nitrate oxygens or U[double bond, length as m-dash]O oxygens and the α-hydrogens in the alkyl chains of the ligands. Comparatively stronger such bonds are found in the UO2(NO3)2·2DsAHP complex. The binding free energies associated with the complexes are computed and favoured superior binding energetics for the more stable UO2(NO3)2·2DsAHP complex. Calculations involving diisoamyl-H-phosphonate (DiAHP) and its complexes have also been performed. Theoretical predictions are experimentally tested by carrying out the extraction of U(vi) from nitric acid media using these ligands. DAHP, DsAHP and DiAHP are synthesised, characterised by NMR and evaluated for their physicochemical properties viz. viscosity, density and aqueous solubility. It was experimentally discovered that indeed DsAHP complexation with uranyl nitrate is more favoured. H-phosphonates are generically classified as acidic extractants owing to the formation of an enol tautomer at lower acidities, hence complexing the metal ion by proton exchange. Our experiments interestingly reveal a neutral ligand characteristic for DsAHP alone which is generically an acidic extractant. Furthermore, the enol tautomer of H-phosphonates that governs their extraction profiles at low acidities is also explored by DFT and the anomalous pH dependent complexation trend of DsAHP could be successfully explained. The extractions of Pu(iv) and Th(iv) have also been carried out in addition to U(vi). Solvent extraction behaviour of Am(iii) was also studied with all three ligands; the positive binding energies computed for the Am(iii) complexation corroborate with our experimental results on the poor extraction of Am(iii).
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Affiliation(s)
- Aditi Chandrasekar
- Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu 603102, India.
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13
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Das A, Ali SM. Understanding of interfacial tension and interface thickness of liquid/liquid interface at a finite concentration of alkyl phosphate by molecular dynamics simulation. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.12.116] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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14
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Vo QN, Dang LX, Nguyen HD, Nilsson M. Microscopic Behaviors of Tri- n-Butyl Phosphate, n-Dodecane, and Their Mixtures at Air/Liquid and Liquid/Liquid Interfaces: An AMBER Polarizable Force Field Study. J Phys Chem B 2019; 123:655-665. [PMID: 30584762 DOI: 10.1021/acs.jpcb.8b08078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In solvent extraction processes for recovering metal ions from used nuclear fuel, as well as other industrial applications, a better understanding of the metal complex phase transfer phenomenon would greatly aid ligand design and process optimization. We have approached this challenge by utilizing the classical molecular dynamics simulations technique to gain visual appreciation of the vapor/liquid and liquid/liquid interface between tri- n-butyl phosphate (TBP) and n-dodecane with air and water. In this study, we successfully reparameterized polarizable force fields for TBP and n-dodecane that accurately reproduced several of their thermophysical properties such as density, heat of vaporization, and dipole moment. Our models were able to predict the surface and interfacial tension of different systems when compared to experimental results that were also performed by us. Through this study, we gained atomistic understanding of the behaviors of TBP and n-dodecane at the interface against air and water, useful in further computational studies of such systems. Finally, our studies indicate that the initial configuration of a simulation may have a large effect on the final result.
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Affiliation(s)
| | - Liem X Dang
- Physical Science Division , Pacific Northwest National Laboratory , Richland , Washington 93352 , United States
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15
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Duvail M, Dumas T, Paquet A, Coste A, Berthon L, Guilbaud P. UO22+ structure in solvent extraction phases resolved at molecular and supramolecular scales: a combined molecular dynamics, EXAFS and SWAXS approach. Phys Chem Chem Phys 2019; 21:7894-7906. [DOI: 10.1039/c8cp07230b] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We developed a polarizable force field for unraveling the UO22+ structure in both aqueous and solvent extraction phases.
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Dwadasi BS, Gupta S, Daware S, Goverapet Srinivasan S, Rai B. Differential Stabilization of the Metal–Ligand Complexes between Organic and Aqueous Phases Drives the Selectivity of Phosphoric Acid Ligands toward Heavier Rare Earth Elements. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b03423] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Balarama Sridhar Dwadasi
- TCS Research, Tata Research Development and Design Centre, 54-B Hadapsar Industrial Estate, Hadapsar, Pune − 411013, Maharashtra, India
| | - Shally Gupta
- TCS Research, Tata Research Development and Design Centre, 54-B Hadapsar Industrial Estate, Hadapsar, Pune − 411013, Maharashtra, India
| | - Santosh Daware
- TCS Research, Tata Research Development and Design Centre, 54-B Hadapsar Industrial Estate, Hadapsar, Pune − 411013, Maharashtra, India
| | - Sriram Goverapet Srinivasan
- TCS Research, Tata Research Development and Design Centre, 54-B Hadapsar Industrial Estate, Hadapsar, Pune − 411013, Maharashtra, India
| | - Beena Rai
- TCS Research, Tata Research Development and Design Centre, 54-B Hadapsar Industrial Estate, Hadapsar, Pune − 411013, Maharashtra, India
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Sahu P, Ali SM, Shenoy KT, Mohan S. Structure, Dynamics, and Adsorption of Charged Guest within the Nanocavity of Polymer-Functionalized Neutral Macrocyclic Host. ACS APPLIED MATERIALS & INTERFACES 2018; 10:20968-20982. [PMID: 29847905 DOI: 10.1021/acsami.8b03874] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Host-guest encapsulation has been widely applied for purification and seizing of the metal ions. Macrocyclic crown ethers are one of the most popular hosts in the field of host-guest chemistry, which on functionalization with polymers are employed as an effective adsorbent. In spite of their vast applications, the microscopic information about their sensing mechanism toward cations/molecules is very scarce. Therefore, the present study is focused on the molecular insights of ion-exchange mechanism within the cavity of crown ether-functionalized polymers using molecular dynamics (MD) simulations. This present study investigates the molecular-level events of chloromethylated polystyrene (CMPS) bearing dibenzo-18-crown-6 (DB18C6) in the aqueous and acidic environment, which has been found to be particularly successful in sensing of various alkali and alkali earth metal ions. A strategy has been envisaged to design a crown ether-based functionalized polymeric resin, which exhibits good match of properties with the in-house-synthesized resin. The MD studies well capture the experimentally observed Langmuir-type adsorption isotherms of Li+ ions on crown ether-grafted polymer resins. The presence of acid reduces the adsorption of Li+ ions due to the competition with H3O+ ions. In addition, the results revealed that the "adsorption in crown cavity" follows a dual residence time function. To the best of our knowledge, this is the first report on the adsorption isotherm of functionalized crown ether using MD simulations. The structure and dynamics of binding sites were explored using radial distribution functions and diffusion coefficients. All of these effects have been studied for different Li+-ion concentrations, acid concentrations, and counterions as well as different lengths of polymer chains and degrees of polymerization. Overall, the present study provides insights into and quantitative information about adsorption on the CMPS-DB18C6 resin, which might be useful in myriads of host-guest-based adsorption experiments.
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Affiliation(s)
- Pooja Sahu
- Bhabha Atomic Research Center , Mumbai 400085 , Maharashtra , India
- Homi Bhabha National Institute , Mumbai 400094 , Maharashtra , India
| | - Sk Musharaf Ali
- Bhabha Atomic Research Center , Mumbai 400085 , Maharashtra , India
- Homi Bhabha National Institute , Mumbai 400094 , Maharashtra , India
| | | | - Sadhana Mohan
- Bhabha Atomic Research Center , Mumbai 400085 , Maharashtra , India
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Sahu P, Ali SM, Shenoy KT, Mohan S. Molecular Facts on the Structure and Dynamics of Electrolyte Species in Cu-Cl Cycle for Hydrogen Generation: An Insight from Molecular Dynamic Simulations. J Phys Chem B 2018; 122:4115-4130. [PMID: 29569915 DOI: 10.1021/acs.jpcb.8b01650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Cu complex, which is the key chemical species in well-known Cu-Cl hybrid thermochemical cycles and also in numerous metal hydrometallurgical and sedimentary deposit processes, displays a wide variety of structural and dynamical characteristics that are further complicated by the presence of multiple oxidation states of Cu ions with different coordination chemistries, therefore they are difficult to explore from experiments alone. In this article, an attempt has been made to understand the coordination behavior of the Cu complex using MD simulations. The study provides compelling evidence of the experimentally observed multiple stoichiometries of Cu ions, i.e., 1:6:0, 1:5:1, and 1:4:2 for Cu+:H2O:Cl- and 1:6:0 for Cu2+:H2O:Cl-. The presence of the anionic Cu complex, [Cu+Cl2]-·2H2O, [Cu+Cl2]-·3H2O, [Cu2+Cl3]-·H2O, and [Cu2+Cl3]-·2H2O, was captured in the presence of excess chloride ions. Furthermore, the probability distribution profiles have been estimated to determine the most possible complex in the considered systems. The results establish structural and dynamical reformation of the Cu complex with change in the salt concentration or variation in the solvent medium in which they are dissolved. Moreover, the structure and kinetics of the Cu ions in the Cu-Cl electrolyzer have been explored over a large range of the electric field by extending the simulated systems for varied strengths of the electric fields. It has been observed that with an increase in the strength of the electric field, the water molecules lose their coordination strength with central Cu ions, which, on the other hand, results in a significant change in the structure of the captured complex. The diffusion dynamics of the ions is altered while applying the electric field, which is furthermore modified while increasing the strength of electric field beyond a critical limit. In fact, the diffusion mechanism of the ions was seen to be transformed from Brownian-like to linear motion and then to hopping diffusion with the increasing strength of the electric field. To the best of our knowledge, this is the first time when the multiple oxidation states of the Cu ion are explored using MD simulations, and the coexisting pictures of the multiple coordinations and the solvent effects have been clearly revealed. Also to date, the present article is the first one to report the insights of the structure and the dynamics of the ions in the Cu-Cl electrolyzer over a wide range of the electric field. The present studies will be very helpful in understanding the mechanism involved in numerous metal hydrometallurgical and sedimentary deposit processes and to comprehend the analogies involved in the electrode reactions of the Cu-Cl cycle for hydrogen generation.
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Affiliation(s)
- Pooja Sahu
- Chemical Engineering Division , Bhabha Atomic Research Center , Mumbai , Maharashtra 400085 , India.,Department of Chemical Science , Homi Bhabha National Institute , Mumbai , Maharashtra 400094 , India
| | - Sk Musharaf Ali
- Chemical Engineering Division , Bhabha Atomic Research Center , Mumbai , Maharashtra 400085 , India.,Department of Chemical Science , Homi Bhabha National Institute , Mumbai , Maharashtra 400094 , India
| | - K T Shenoy
- Chemical Engineering Division , Bhabha Atomic Research Center , Mumbai , Maharashtra 400085 , India
| | - S Mohan
- Chemical Engineering Division , Bhabha Atomic Research Center , Mumbai , Maharashtra 400085 , India
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Das A, Ali SM. Molecular dynamics simulation for the test of calibrated OPLS-AA force field for binary liquid mixture of tri-iso-amyl phosphate and n-dodecane. J Chem Phys 2018; 148:074502. [PMID: 29471660 DOI: 10.1063/1.5009900] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Tri-isoamyl phosphate (TiAP) has been proposed to be an alternative for tri-butyl phosphate (TBP) in the Plutonium Uranium Extraction (PUREX) process. Recently, we have successfully calibrated and tested all-atom optimized potentials for liquid simulations using Mulliken partial charges for pure TiAP, TBP, and dodecane by performing molecular dynamics (MD) simulation. It is of immense importance to extend this potential for the various molecular properties of TiAP and TiAP/n-dodecane binary mixtures using MD simulation. Earlier, efforts were devoted to find out a suitable force field which can explain both structural and dynamical properties by empirical parameterization. Therefore, the present MD study reports the structural, dynamical, and thermodynamical properties with different mole fractions of TiAP-dodecane mixtures at the entire range of mole fraction of 0-1 employing our calibrated Mulliken embedded optimized potentials for liquid simulation (OPLS) force field. The calculated electric dipole moment of TiAP was seen to be almost unaffected by the TiAP concentration in the dodecane diluent. The calculated liquid densities of the TiAP-dodecane mixture are in good agreement with the experimental data. The mixture densities at different temperatures are also studied which was found to be reduced with temperature as expected. The plot of diffusivities for TiAP and dodecane against mole fraction in the binary mixture intersects at a composition in the range of 25%-30% of TiAP in dodecane, which is very much closer to the TBP/n-dodecane composition used in the PUREX process. The excess volume of mixing was found to be positive for the entire range of mole fraction and the excess enthalpy of mixing was shown to be endothermic for the TBP/n-dodecane mixture as well as TiAP/n-dodecane mixture as reported experimentally. The spatial pair correlation functions are evaluated between TiAP-TiAP and TiAP-dodecane molecules. Further, shear viscosity has been computed by performing the non-equilibrium molecular dynamics employing the periodic perturbation method. The calculated shear viscosity of the binary mixture is found to be in excellent agreement with the experimental values. The use of the newly calibrated OPLS force field embedding Mulliken charges is shown to be equally reliable in predicting the structural and dynamical properties for the mixture without incorporating any arbitrary scaling in the force field or Lennard-Jones parameters. Further, the present MD simulation results demonstrate that the Stokes-Einstein relation breaks down at the molecular level. The present methodology might be adopted to evaluate the liquid state properties of an aqueous-organic biphasic system, which is of great significance in the interfacial science and technology.
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Affiliation(s)
- Arya Das
- Nuclear Recycle Board, Bhabha Atomic Research Centre, Mumbai 400094, India
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20
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Kusaka R, Watanabe M. Mechanism of phase transfer of uranyl ions: a vibrational sum frequency generation spectroscopy study on solvent extraction in nuclear reprocessing. Phys Chem Chem Phys 2018; 20:29588-29590. [DOI: 10.1039/c8cp04558e] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
VSFG study on interfaces of TBP/uranyl aqueous solutions shows that uranyl ion does not form complexes with TBP at the interface, and proposes a new extraction mechanism.
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Affiliation(s)
- Ryoji Kusaka
- Nuclear Science and Engineering Center
- Japan Atomic Energy Agency (JAEA)
- Tokai
- Japan
| | - Masayuki Watanabe
- Nuclear Science and Engineering Center
- Japan Atomic Energy Agency (JAEA)
- Tokai
- Japan
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21
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Sahu P, Musharaf Ali S, Shenoy KT. TBP Assisted Uranyl Extraction in Water-Dodecane Biphasic System: Insights from Molecular Dynamics Simulation. CHEMICAL PRODUCT AND PROCESS MODELING 2017. [DOI: 10.1515/cppm-2016-0024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
In the PUREX (Plutonium Uranium Recovery by Extraction Process) process, the extraction of uranyl ion from dissolver solution to the organic phase is influenced by co extraction of the other species, such as water and nitric acid and it is assumed that the presence of water or acid droplets in the organic phase intensifies the coordination mechanism of TBP. The present study illustrates the uranyl extraction from the aqueous phase to the organic phase using molecular dynamics (MD) simulation. Here, we consider the biphasic systems to gain insights into the characteristics of the interface and humidity of the organic phase under different acidic and neutral conditions. MD being a force field method, can’t satisfactorily model the bond making and breaking process therefore a priori choice has been made concerning the different status of proton for the acidic phase. Further, the importance of charge species transferability during uranyl-TBP complexation have been investigated considering two different models of uranyl nitrate; united UO2(NO3)2 complex and separate UO2
2+ and NO3
– ions. From the results, it is recommended to use the ionic uranyl model with separate UO2
2+ and NO3
– to study the structural and dynamical properties of extracted uranyl ions in the organic phase. Also, it was noticed that extracted uranyl ions in the organic phase are not completely dehydrated but are surrounded by water molecules. In other words the results show co extraction of other species such as water and acid molecules to the organic phase. Most remarkably, the present study evident that the neutral HNO3 effectively represents the acidity effect for the receiving phase in terms of acid/water extraction and their aggregation to form water droplet, especially when ionic model of uranyl nitrate is considered.
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Affiliation(s)
- Pooja Sahu
- Chemical Engineering Division , Bhabha Atomic Research Centre, HBNI, Trombay , Mumbai 400 085 , India
| | - Sk. Musharaf Ali
- Chemical Engineering Division , Bhabha Atomic Research Centre, HBNI, Trombay , Mumbai 400 085 , India
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Wen B, Sun C, Bai B, Gatapova EY, Kabov OA. Ionic hydration-induced evolution of decane–water interfacial tension. Phys Chem Chem Phys 2017; 19:14606-14614. [DOI: 10.1039/c7cp01826f] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We show that ionic hydration is responsible for the non-monotonic variation of the interfacial tension with increasing ionic concentration.
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Affiliation(s)
- Boyao Wen
- State Key Laboratory of Multiphase Flow in Power Engineering
- Xi'an Jiaotong University
- Xian
- China
| | - Chengzhen Sun
- State Key Laboratory of Multiphase Flow in Power Engineering
- Xi'an Jiaotong University
- Xian
- China
| | - Bofeng Bai
- State Key Laboratory of Multiphase Flow in Power Engineering
- Xi'an Jiaotong University
- Xian
- China
| | - Elizaveta Ya. Gatapova
- Kutateladze Institute of Thermophysics
- Siberian Branch of the Russian Academy of Sciences
- Novosibirsk 630090
- Russia
- Novosibirsk State University
| | - Oleg A. Kabov
- Kutateladze Institute of Thermophysics
- Siberian Branch of the Russian Academy of Sciences
- Novosibirsk 630090
- Russia
- Novosibirsk State University
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Servis MJ, Wu DT, Braley JC. Network analysis and percolation transition in hydrogen bonded clusters: nitric acid and water extracted by tributyl phosphate. Phys Chem Chem Phys 2017; 19:11326-11339. [DOI: 10.1039/c7cp01845b] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Network analysis of hydrogen bonded clusters formed in simulation by extraction of nitric acid and water by TBP interprets cluster topologies and identifies the mechanism for third phase formation.
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