1
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Ow MJK, Yeow EKL. Revealing the Existence of Long-Range Liquid-Liquid Interfacial Potential in Phase-Transfer Processes. J Phys Chem Lett 2024; 15:6241-6248. [PMID: 38842186 DOI: 10.1021/acs.jpclett.4c01135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
By employing fluorescence wide-field microscopy and a nanoparticle-based phase transfer catalyst (PTC), consisting of a fluorescent silica nanoparticle functionalized with trioctylpropylammonium bromide, we demonstrate that in the presence of NaOH, single nanoparticles display subdiffusive motion along the axis normal to an aqueous liquid-organic liquid interface. This is because of an extended interfacial potential with a shallow well (∼1 kBT) that stretches a few μm into the organic phase, in contrast to previous molecular dynamics studies that reported narrow interfaces on the order of ∼1 nm. Spontaneous interfacial emulsification induced by NaOH results in the propagation of water-in-oil nanoemulsions into the organic solvent that creates an equilibrium hybrid-solvent composition that solvates the PTC. A greater mobility and longer residence time of the PTC at the potential well enhance the interfacial phase transfer process and catalytic efficiency.
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Affiliation(s)
- Matthew J K Ow
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Edwin K L Yeow
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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2
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Uysal A. Aqueous Interfaces in Chemical Separations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37917551 DOI: 10.1021/acs.langmuir.3c02170] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Chemical separations play a vital role in refinery and reprocessing of critical materials, such as platinum group metals, rare earths, and actinides. The choice of separation system─whether it is liquid-liquid extraction (LLE), sorbents, or membranes─depends on specific needs and applications. In almost all separation processes, the desired metal ions adsorb or transfer across an aqueous interface, such as the solid/liquid interface in sorbents or oil/water interfaces in LLE. Despite these separation technologies being extensively used for decades, our understanding of the molecular-scale mechanisms governing ion adsorption and transport at interfaces remains limited. This knowledge gap presents a significant challenge in meeting the increasing demands for these critical materials due to their growing use in advanced technologies. Fortunately, recent advancements in surface-specific experimental and computational techniques offer promising avenues to bridge this gap and facilitate the development of next-generation separation systems. Interestingly, unanswered questions regarding interfacial phenomena in chemical separations hold great relevance to various fields, including energy storage, geochemistry, and atmospheric chemistry. Therefore, the model interfacial systems developed for studying chemical separations, such as amphiphilic molecules assembled at a solid/water, air/water, or oil/water interface, may have far-reaching implications, extending beyond separations and opening doors to addressing a wide range of scientific inquiries. This perspective discusses recent interfacial studies elucidating amphiphile-ion interactions in chemical separations of metal ions. These studies provide direct, molecular-scale information about solute and solvent behavior at aqueous interfaces, including multivalent and complex ions in highly concentrated solutions, which play key roles in LLE of critical materials.
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Affiliation(s)
- Ahmet Uysal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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3
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Sun P, Binter EA, Vo T, Benjamin I, Bera MK, Lin B, Bu W, Schlossman ML. Relevance of Surface Adsorption and Aqueous Complexation for the Separation of Co(II), Ni(II), and Fe(III). J Phys Chem B 2023; 127:3505-3515. [PMID: 37018762 DOI: 10.1021/acs.jpcb.2c08412] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
During the solvent extraction of metal ions from an aqueous to an organic phase, organic-soluble extractants selectively target aqueous-soluble ions for transport into the organic phase. In the case of extractants that are also soluble in the aqueous phase, our recent studies of lanthanide ion-extractant complexes at the surface of aqueous solutions suggested that ion-extractant complexation in the aqueous phase can hinder the solvent extraction process. Here, we investigate a similar phenomenon relevant to the separation of Co(II), Ni(II), and Fe(III). X-ray fluorescence near total reflection and tensiometry are used to characterize ion adsorption behavior at the surface of aqueous solutions containing water-soluble extractants, either bis(2-ethylhexyl) phosphoric acid (HDEHP) or 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEHEHP), as well as adsorption to a monolayer of water-insoluble extractant dihexadecyl phosphoric acid (DHDP) at the aqueous-vapor interface. Competitive adsorption of Ni(II) and Fe(III) utilizing either HDEHP or DHDP illustrates the essential feature of the recent lanthanide studies that the ion, which is preferentially extracted in liquid-liquid extraction, Fe(III), is found preferentially adsorbed to the water-vapor interface only in the presence of the water-insoluble extractant DHDP. A more subtle competition produces comparable adsorption behavior of Co(II) and Ni(II) at the surfaces of both HDEHP- and HEHEHP-aqueous solutions in spite of the known preference for Co(II) under solvent extraction conditions. Comparison experiments with a monolayer of DHDP reveal that Co(II) is preferentially adsorbed to the surface. This preference for Co(II) is also supported by molecular dynamics simulations of the potential of mean force of ions interacting with the soluble extractants in water. These results highlight the possibility that complexation of extractants and ions in the aqueous phase can alter selectivity in the solvent extraction of critical elements.
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Affiliation(s)
- Pan Sun
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
- NSF's ChemMatCARS, Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Erik A Binter
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Trung Vo
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Ilan Benjamin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Mrinal K Bera
- NSF's ChemMatCARS, Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- NSF's ChemMatCARS, Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Wei Bu
- NSF's ChemMatCARS, Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Mark L Schlossman
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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4
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Micheau C, Ueda Y, Akutsu-Suyama K, Bourgeois D, Motokawa R. Deuterated Malonamide Synthesis for Fundamental Research on Solvent Extraction Systems. SOLVENT EXTRACTION AND ION EXCHANGE 2023. [DOI: 10.1080/07366299.2023.2166351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Cyril Micheau
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan
| | - Yuki Ueda
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan
| | - Kazuhiro Akutsu-Suyama
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki, Japan
| | - Damien Bourgeois
- Institut de Chimie Séparative de Marcoule, ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Marcoule, France Bagnols-sur-Cèze
| | - Ryuhei Motokawa
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan
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5
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Kusaka R, Watanabe M. Development of Heavy Element Chemistry at Interfaces: Observing Actinide Complexes at the Oil/Water Interface in Solvent Extraction by Nonlinear Vibrational Spectroscopy. J Phys Chem Lett 2022; 13:7065-7071. [PMID: 35900124 PMCID: PMC9358700 DOI: 10.1021/acs.jpclett.2c01550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Understanding the chemistry of elements at the bottom of the periodic table is a challenging goal in chemistry. Observing actinide species at interfaces by using interface-selective second-order nonlinear optical spectroscopy, such as vibrational sum frequency generation (VSFG) spectroscopy, is a promising route for developing heavy element chemistry; however, such attempts are scarce. Here, we investigated the phase transfer mechanism of uranyl ions (UO22+) in solvent extraction using the di(2-ethylhexyl)phosphoric acid (HDEHP) extractant dissolved in the dodecane organic phase by probing the oil/water liquid-liquid interface using VSFG spectroscopy. The POO- symmetric stretch vibrational signals of the HDEHP ligands clearly demonstrated that uranyl ions form interfacial complexes with HDEHP at the oil/water interface. The interfacial uranyl-HDEHP complexes were formed with uranyl ions coming from both the aqueous and oil phases, strongly suggesting that the interfacial complex is an intermediate to cross the oil/water interface. Density functional theory calculations proposed the molecular structure of the interfacial uranyl-HDEHP complex.
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6
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Nayak S, Kumal RR, Uysal A. Spontaneous and Ion-Specific Formation of Inverted Bilayers at Air/Aqueous Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5617-5625. [PMID: 35482964 DOI: 10.1021/acs.langmuir.2c00208] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Developing better separation technologies for rare earth metals, an important aspect of a sustainable materials economy, is challenging due to their chemical similarities. Identifying molecular-scale interactions that amplify the subtle differences between the rare earths can be useful in developing new separation technologies. Here, we describe the ion-dependent monolayer to inverted bilayer transformation of extractant molecules at the air/aqueous interface. The inverted bilayers form with Lu3+ ions but not with Nd3+. By introducing Lu3+ ions to preformed monolayers, we extract kinetic parameters corresponding to the monolayer to inverted bilayer conversion. Temperature-dependent studies show Arrhenius behavior with an energy barrier of 40 kcal/mol. The kinetics of monolayer to inverted bilayer conversion is also affected by the character of the background anion, although anions are expected to be repelled from the interface. Our results show the outsized importance of ion-specific effects on interfacial structure and kinetics, pointing to their role in chemical separation methods.
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Affiliation(s)
- Srikanth Nayak
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Raju R Kumal
- 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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7
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Enhanced interfacial salt effect on extraction and separation of Er(III) from Mg(II), Al(III), Fe(III) sulfate aqueous solutions using bubble-supported organic liquid membrane. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2021.120344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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8
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New Design of a Sample Cell for Neutron Reflectometry in Liquid–Liquid Systems and Its Application for Studying Structures at Air–Liquid and Liquid–Liquid Interfaces. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12031215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Knowledge of interfacial structures in liquid–liquid systems is imperative, especially for improving two-phase biological and chemical reactions. Therefore, we developed a new sample cell for neutron reflectometry (NR), which enables us to observe the layer structure around the interface, and investigated the adsorption behavior of a typical surfactant, sodium dodecyl sulfate (SDS), on the toluene-d8-D2O interface under the new experimental conditions. The new cell was characterized by placing the PTFE frame at the bottom to produce a smooth interface and downsized compared to the conventional cell. The obtained NR profiles were readily analyzable and we determined a slight difference in the SDS adsorption layer structure at the interface between the toluene-d8-D2O and air-D2O systems. This could be owing to the difference in the adsorption behavior of the SDS molecules depending on the interfacial conditions.
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9
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Li W, Wang R, Jiang HX, Chen Y, Tang AN, Kong DM. Controllable synthesis of uniform large-sized spherical covalent organic frameworks for facile sample pretreatment and as naked-eye indicator. Talanta 2022; 236:122829. [PMID: 34635219 DOI: 10.1016/j.talanta.2021.122829] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/23/2021] [Accepted: 08/25/2021] [Indexed: 12/14/2022]
Abstract
The successful application of covalent organic frameworks (COFs) depends on not only their unique chemical structures but also their morphology, size, and architecture. Spherical COFs (SCOFs) are attracted special attention due to the superiority of spherical materials in many applications. However, the synthesis of uniform large-sized SCOFs remains a challenge. Herein, by carefully optimizing the synthesis of a heteropore COF, we find that solvent type and catalyst concentration play important roles in determining the morphology and size of COFs, and eventually achieve the controllable synthesis of large SCOFs with uniform sizes ranging from 200 μm to 5 mm. The obtained SCOFs keep the dual-pore feature of the heteropore COF and show good stability and high crystallinity. To exhibit the superior application potential of SCOFs, the SCOFs with a size range of 200-300 μm were demonstrated to be promising solid-phase extraction (SPE) fillers. As-prepared SCOFs-packed SPE column could effectively remove ≥99% phytochrome matrix from 6 different vegetable samples in 10 s, accompanied by 72.56-112.37% recoveries of 33 chemical hazards with different physicochemical properties, thus showing greatly promising application prospects in sample pretreatment of nontargeted food safety analysis. By utilizing acid/base-adjusted reversible color change, millimeter-sized SCOFs were developed as an easy-to-operate and reusable naked-eye indicator of acids.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China
| | - Rui Wang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China
| | - Hong-Xin Jiang
- Agro-Environmental Protection Institute, Key Laboratory for Environmental Factors Control of Agro-product Quality Safety, Laboratory of Environmental Factors Risk Assessment of Agro-Product Quality Safety, Ministry of Agriculture, Tianjin, 300191, People's Republic of China
| | - Yan Chen
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China
| | - An-Na Tang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China
| | - De-Ming Kong
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin, 300071, People's Republic of China.
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10
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Premadasa UI, Ma YZ, Sacci RL, Bocharova V, Thiele NA, Doughty B. Understanding Self-Assembly and the Stabilization of Liquid/Liquid Interfaces: The Importance of Ligand Tail Branching and Oil-Phase Solvation. J Colloid Interface Sci 2021; 609:807-814. [PMID: 34872722 DOI: 10.1016/j.jcis.2021.11.088] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 01/05/2023]
Abstract
HYPOTHESIS Organophosphorus-based ligands represent a versatile set of solvent extraction reagents whose chemical makeup plays an important role in extraction mechanism. We hypothesize that the branching of the extractant hydrophobic tail and its oil-phase solvation affect the liquid/liquid interfacial structure. Understanding the structure mediated adsorption and interfacial ordering becomes key in designing ligands with enhanced selectivity and efficiency for targeted extractions. EXPERIMENT We employed vibrational sum frequency generation spectroscopy and interfacial tension measurements to extract thermodynamic adsorption energies, map interfacial ordering, and rationalize disparate behaviors of model di-(2-ethylhexyl) phosphoric acid and dioctyl phosphoric acid ligands at the hexadecane water interface. FINDINGS With increased surface loading, ligands with branched hydrophobic tails formed stable interfaces at much lower concentrations than those observed for ligands with linear alkyl tails. The lack of an oil phase and associated solvation results in markedly different interfacial properties, and thus measurements made at air/liquid surfaces cannot be assumed to correlate with the processes occurring at buried liquid/liquid interfaces. We attribute these differences in the surface mediated self-assembly to key variations in hydrophobic interactions and tail solvation taking place in the oil phase demonstrating that interactions in both the polar and nonpolar phases are essential to understand self-assembly and function.
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Affiliation(s)
- Uvinduni I Premadasa
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Ying-Zhong Ma
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Robert L Sacci
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Vera Bocharova
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Nikki A Thiele
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Benjamin Doughty
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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11
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Usma CL, Dourdain S, Arrachart G, Pellet-Rostaing S. Solvent extraction of rare earths elements from nitrate media in DMDOHEMA/ionic liquid systems: performance and mechanism studies. RSC Adv 2021; 11:31197-31207. [PMID: 35496839 PMCID: PMC9041442 DOI: 10.1039/d1ra05359k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 09/12/2021] [Indexed: 01/18/2023] Open
Abstract
Extraction of La(iii), Eu(iii) and Fe(iii) was compared in n-dodecane and two ionic liquids (ILs) (1-ethyl-1-butylpiperidinium bis (trifluoromethylsulfonyl)imide [EBPip+] [NTf2−] and 1-ethyl-1-octylpiperidinium bis (trifluoromethylsulfonyl)imide [EOPip+] [NTf2−]). Using the extractant N,N′-dimethyl-N,N′-dioctylhexylethoxymalonamide (DMDOHEMA), the effect of pH was investigated in detail to recover extraction mechanisms. The use of ILs as the organic solvent instead of n-dodecane, greatly enhances extraction efficiency, and an ionic liquid with a shorter alkyl chain [EBPip+] [NTf2−] provides higher extraction than [EOPip+] [NTf2−]. The mechanistic study points out that for low nitric acid concentrations ([HNO3] ≤ 0.01 M), metal is extracted via a cation of the ionic liquids, while for higher nitric acid concentrations ([HNO3] ≥ 1.0 M), extraction occurs through pure solvation mechanism of DMDOHEMA as in conventional diluents. This latter case is of high interest for applications, as higher extraction can be obtained without any loss of ILs by ion exchange mechanisms. Extraction of La(iii), Eu(iii) and Fe(iii) was compared in n-dodecane and in two ionic liquids (ILs) [EBPip+] [NTf2−] and [EOPip+] [NTf2−]. Extraction mechanisms have been investigated as a function of pH.![]()
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Affiliation(s)
- Cesar L Usma
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule France
| | - S Dourdain
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule France
| | - G Arrachart
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule France
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12
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Špadina M, Dufrêche JF, Pellet-Rostaing S, Marčelja S, Zemb T. Molecular Forces in Liquid-Liquid Extraction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10637-10656. [PMID: 34251218 DOI: 10.1021/acs.langmuir.1c00673] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The phase transfer of ions is driven by gradients of chemical potentials rather than concentrations alone (i.e., by both the molecular forces and entropy). Extraction is a combination of high-energy interactions that correspond to short-range forces in the first solvation shell such as ion pairing or complexation forces, with supramolecular and nanoscale organization. While the latter are similar to the long-range solvent-averaged interactions in the colloidal world, in solvent extraction they are associated with lower characteristic lengths of the nanometric domain. Modeling of such complex systems is especially complicated because the two domains are coupled, whereas the resulting free energy of extraction is around kBT to guarantee the reversibility of the practical process. Nevertheless, quantification is possible by considering a partitioning of space among the polar cores, interfacial film, and solvent. The resulting free energy of transfer can be rationalized by utilizing a combination of terms which represent strong complexation energies, counterbalanced by various entropic effects and the confinement of polar solutes in nanodomains dispersed in the diluent, together with interfacial extractant terms. We describe here this ienaics approach in the context of solvent extraction systems; it can also be applied to further complex ionic systems, such as membranes and biological interfaces.
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Affiliation(s)
- Mario Špadina
- Group for Computational Life Sciences, Rud̵er Bošković Institute, Division of Physical Chemistry, 10000 Zagreb, Croatia
- Faculty of Health Sciences, University of Ljubljana, 1000 Ljubljana, Slovenia
| | | | | | - Stjepan Marčelja
- Research School of Physics, The Australian National University, Canberra, Australia
| | - Thomas Zemb
- ICSM, CEA, CNRS, ENSCM, Université Montpellier, Marcoule, France
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13
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Neutron reflectometry study of the interface between two immiscible electrolyte solutions: Effects of electrolyte concentration, applied electric field, and lipid adsorption. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138336] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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14
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Marion S, Vučemilović-Alagić N, Špadina M, Radenović A, Smith AS. From Water Solutions to Ionic Liquids with Solid State Nanopores as a Perspective to Study Transport and Translocation Phenomena. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2100777. [PMID: 33955694 DOI: 10.1002/smll.202100777] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/01/2021] [Indexed: 06/12/2023]
Abstract
Solid state nanopores are single-molecular devices governed by nanoscale physics with a broad potential for technological applications. However, the control of translocation speed in these systems is still limited. Ionic liquids are molten salts which are commonly used as alternate solvents enabling the regulation of the chemical and physical interactions on solid-liquid interfaces. While their combination can be challenging to the understanding of nanoscopic processes, there has been limited attempts on bringing these two together. While summarizing the state of the art and open questions in these fields, several major advances are presented with a perspective on the next steps in the investigations of ionic-liquid filled nanopores, both from a theoretical and experimental standpoint. By analogy to aqueous solutions, it is argued that ionic liquids and nanopores can be combined to provide new nanofluidic functionalities, as well as to help resolve some of the pertinent problems in understanding transport phenomena in confined ionic liquids and providing better control of the speed of translocating analytes.
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Affiliation(s)
- Sanjin Marion
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015, Lausanne, Switzerland
| | - Nataša Vučemilović-Alagić
- Group for Computational Life Sciences, Ruđer Bošković Institute, Division of Physical Chemistry, 10000, Zagreb, Croatia
- PULS Group, Physics Department, Interdisciplinary Center for Nanostructured Films, FAU Erlangen-Nürnberg, 91058, Erlangen, Germany
| | - Mario Špadina
- Group for Computational Life Sciences, Ruđer Bošković Institute, Division of Physical Chemistry, 10000, Zagreb, Croatia
| | - Aleksandra Radenović
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, 1015, Lausanne, Switzerland
| | - Ana-Sunčana Smith
- Group for Computational Life Sciences, Ruđer Bošković Institute, Division of Physical Chemistry, 10000, Zagreb, Croatia
- PULS Group, Physics Department, Interdisciplinary Center for Nanostructured Films, FAU Erlangen-Nürnberg, 91058, Erlangen, Germany
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15
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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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16
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Špadina M, Dourdain S, Rey J, Bohinc K, Pellet-Rostaing S, Dufrêche JF, Zemb T. How acidity rules synergism and antagonism in liquid–liquid extraction by lipophilic extractants—Part II: application of the ienaic modelling. SOLVENT EXTRACTION AND ION EXCHANGE 2021. [DOI: 10.1080/07366299.2021.1899614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M. Špadina
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
- Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - S. Dourdain
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
| | - J. Rey
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
| | - K. Bohinc
- Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | | | | | - T. Zemb
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
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17
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Nayak S, Lovering K, Uysal A. Ion-specific clustering of metal-amphiphile complexes in rare earth separations. NANOSCALE 2020; 12:20202-20210. [PMID: 32969439 DOI: 10.1039/d0nr04231e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The nanoscale structure of a complex fluid can play a major role in the selective adsorption of ions at the nanometric interfaces, which is crucial in industrial and technological applications. Here we study the effect of anions and lanthanide ions on the nanoscale structure of a complex fluid formed by metal-amphiphile complexes, using small angle X-ray scattering. The nano- and mesoscale structures we observed can be directly connected to the preferential transfer of light (La and Nd) or heavy (Er and Lu) lanthanides into the complex fluid from an aqueous solution. While toluene-based complex fluids containing trioctylmethylammonium-nitrate (TOMA-nitrate) always show the same mesoscale hierarchical structure regardless of lanthanide loading and prefer light lanthanides, those containing TOMA-thiocyanate show an evolution of the mesoscale structure as a function of the lanthanide loading and prefer heavy lanthanides. The hierarchical structure indicates the presence of attractive interactions between ion-amphiphile aggregates, causing them to form clusters. A clustering model that accounts for the hard sphere repulsions and short-range attractions between the aggregates has been adapted to model the X-ray scattering results. The new model successfully describes the nanoscale structure and helps in understanding the mechanisms responsible for amphiphile assisted ion transport between immiscible liquids. Accordingly, our results imply different mechanisms of lanthanide transport depending on the anion present in the complex fluid and correspond with anion-dependent trends in rare earth separations.
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Affiliation(s)
- Srikanth Nayak
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA.
| | - Kaitlin Lovering
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA.
| | - Ahmet Uysal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA.
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Chowdhury AU, Lin L, Doughty B. Hydrogen-Bond-Driven Chemical Separations: Elucidating the Interfacial Steps of Self-Assembly in Solvent Extraction. ACS APPLIED MATERIALS & INTERFACES 2020; 12:32119-32130. [PMID: 32551500 DOI: 10.1021/acsami.0c06176] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Chemical separations, particularly liquid extractions, are pervasive in academic and industrial laboratories, yet a mechanistic understanding of the events governing their function are obscured by interfacial phenomena that are notoriously difficult to measure. In this work, we investigate the fundamental steps of ligand self-assembly as driven by changes in the interfacial H-bonding network using vibrational sum frequency generation. Our results show how the bulk pH modulates the interfacial structure of extractants at the buried oil/aqueous interface via the formation of unique H-bonding networks that order and bridge ligands to produce self-assembled aggregates. These extended H-bonded structures are key to the subsequent extraction of Co2+ from the aqueous phase in promoting micelle formation and subsequent ejection of the said micelle into the oil phase. The combination of static and time-resolved measurements reveals the events underlying complexities of liquid extractions at high [Co2+]:[ligand] ratios by showing an evolution of interfacially assembled structures that are readily tuned on a chemical basis by altering the compositions of the aqueous phase. The results of this work point to new principles to design-applied separations through the manipulation of surface charge, electrostatic screening, and the associated H-bonding networks that arise at the interface to facilitate organization and subsequent extraction.
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Affiliation(s)
- Azhad U Chowdhury
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Lu Lin
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Benjamin Doughty
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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Nayak S, Lovering K, Bu W, Uysal A. Anions Enhance Rare Earth Adsorption at Negatively Charged Surfaces. J Phys Chem Lett 2020; 11:4436-4442. [PMID: 32406689 DOI: 10.1021/acs.jpclett.0c01091] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Anions are expected to be repelled from negatively charged surfaces. At aqueous interfaces, however, ion-specific effects can dominate over direct electrostatic interactions. Using multiple in situ surface sensitive experimental techniques, we show that surface affinities of SCN- anions are so strong that they can adsorb at a negatively charged floating monolayer at the air-aqueous interface. This extreme example of ion-specific effects may be very important for understanding complex processes at aqueous interfaces, such as chemical separations of rare earth metals. Adsorbed SCN- ions at the floating monolayer increase the overall negative charge density, leading to enhanced trivalent rare earth adsorption. Surface sensitive X-ray fluorescence measurements show that the surface coverage of Lu3+ ions can be triple the apparent surface charge of the floating monolayer in the presence of SCN-. Comparison to NO3- samples shows that the effects are strongly dependent on the character of the anion, providing further evidence of ion-specific effects dominating over electrostatics.
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Affiliation(s)
- Srikanth Nayak
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Kaitlin Lovering
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Wei Bu
- NSF's ChemMatCARS, The University of Chicago, Chicago, Illinois 60637, United States
| | - Ahmet Uysal
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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20
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Binder C, Lageder B, Bradshaw-Hajek BH, Fischmann AJ, Priest C. Microvolume Screening of Extraction and Phase Behavior in a Liquid-Liquid Microsystem. Anal Chem 2020; 92:7831-7835. [PMID: 32352760 DOI: 10.1021/acs.analchem.0c01050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Spontaneous formation of a third immiscible phase during liquid-liquid solvent extraction presents an enormous technical challenge for industry. Insight from current empirical investigations is greatly limited by the lack of methodologies that simultaneously report the progress of the extraction, third-phase onset time, and chemical and physical nature. The microfluidic strategy presented here answers this challenge by supporting an optically transparent submicroliter organic-phase film in a micropillar array surrounded by the aqueous phase. To demonstrate, we used 1 M Cyanex 572 in Shellsol D70 (organic phase) to extract Yb3+ and Dy3+ from a pH 2 aqueous phase. Real-time optical tracking confirmed that the visual onset of third-phase formation is consistent with the cessation of extraction (at the loading limit). Spectroscopic analysis of the solid-like third phase was carried out successfully. The new analytical approach offers a step change in speed and efficiency for reagent development, process control, and fundamental studies of complex phase behavior in reactive multiphase systems.
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Affiliation(s)
- Claudia Binder
- Future Industries Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia
| | - Benjamin Lageder
- Future Industries Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia
| | | | - Adam J Fischmann
- Centre for Advanced Materials and Industrial Chemistry, School of Science, RMIT University, Melbourne, Victoria 3001, Australia
| | - Craig Priest
- Future Industries Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia
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21
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Importance of weak interactions in the formulation of organic phases for efficient liquid/liquid extraction of metals. Curr Opin Colloid Interface Sci 2020. [DOI: 10.1016/j.cocis.2020.03.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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22
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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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23
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Narayanan T, Konovalov O. Synchrotron Scattering Methods for Nanomaterials and Soft Matter Research. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E752. [PMID: 32041363 PMCID: PMC7040635 DOI: 10.3390/ma13030752] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 01/29/2020] [Accepted: 01/31/2020] [Indexed: 12/17/2022]
Abstract
This article aims to provide an overview of broad range of applications of synchrotron scattering methods in the investigation of nanoscale materials. These scattering techniques allow the elucidation of the structure and dynamics of nanomaterials from sub-nm to micron size scales and down to sub-millisecond time ranges both in bulk and at interfaces. A major advantage of scattering methods is that they provide the ensemble averaged information under in situ and operando conditions. As a result, they are complementary to various imaging techniques which reveal more local information. Scattering methods are particularly suitable for probing buried structures that are difficult to image. Although, many qualitative features can be directly extracted from scattering data, derivation of detailed structural and dynamical information requires quantitative modeling. The fourth-generation synchrotron sources open new possibilities for investigating these complex systems by exploiting the enhanced brightness and coherence properties of X-rays.
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24
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Wang X, Huang K, Cao W, Sun P, Sui N, Song W, Liu H. Enhanced separation of praseodymium and neodymium by kinetic “push and pull” system of [A336][NO3]-DTPA in a column extractor. J RARE EARTH 2020. [DOI: 10.1016/j.jre.2019.03.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Reflectometry Reveals Accumulation of Surfactant Impurities at Bare Oil/Water Interfaces. Molecules 2019; 24:molecules24224113. [PMID: 31739471 PMCID: PMC6891303 DOI: 10.3390/molecules24224113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/06/2019] [Accepted: 11/09/2019] [Indexed: 12/04/2022] Open
Abstract
Bare interfaces between water and hydrophobic media like air or oil are of fundamental scientific interest and of great relevance for numerous applications. A number of observations involving water/hydrophobic interfaces have, however, eluded a consensus mechanistic interpretation so far. Recent theoretical studies ascribe these phenomena to an interfacial accumulation of charged surfactant impurities in water. In the present work, we show that identifying surfactant accumulation with X-ray reflectometry (XRR) or neutron reflectometry (NR) is challenging under conventional contrast configurations because interfacial surfactant layers are then hardly visible. On the other hand, both XRR and NR become more sensitive to surfactant accumulation when a suitable scattering length contrast is generated by using fluorinated oil. With this approach, significant interfacial accumulation of surfactant impurities at the bare oil/water interface is observed in experiments involving standard cleaning procedures. These results suggest that surfactant impurities may be a limiting factor for the investigation of fundamental phenomena involving water/hydrophobic interfaces.
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26
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Solvent extraction kinetics of Ag(I) with methyl ketonic p-tert-octylcalix[4]arene in the modified Lewis cell technique. J INCL PHENOM MACRO 2019. [DOI: 10.1007/s10847-018-0807-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Skoda MW. Recent developments in the application of X-ray and neutron reflectivity to soft-matter systems. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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28
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Delcea M, Helm CA. X-ray and Neutron Reflectometry of Thin Films at Liquid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8519-8530. [PMID: 30901219 DOI: 10.1021/acs.langmuir.8b04315] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the 1980s, Helmuth Möhwald studied lipid monolayers at the air/water interface to understand the thermodynamically characterized phases at the molecular level. In collaboration with Jens Als-Nielsen, X-ray reflectometry was used and further developed to determine the electron density profile perpendicular to the water surface. Using a slab model, parameters such as thickness and density of the individual molecular regions, as well as the roughness of the individual interfaces, were determined. Later, X-ray and neutron reflectometry helped to understand the coverage and conformation of anchored and adsorbed polymers. Nowadays, they resolve molecular properties in emerging topics such as liquid metals and ionic liquids. Much is still to be learned about buried interfaces (e.g., liquid/liquid interfaces). In this Article, a historical and theoretical background of X-ray reflectivity is given, recent developments of X-ray and neutron reflectometry for polymers at interfaces and thin layers are highlighted, and emerging research topics involving these techniques are emphasized.
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Affiliation(s)
- Mihaela Delcea
- Institute of Biochemistry , University of Greifswald , Felix-Hausdorff-Straße 4 , 17489 Greifswald , Germany
- ZIK HIKE- Zentrum für Innovationskompetenz , Humorale Immunreaktionen bei kardiovaskulären Erkrankungen , Fleischmannstraße 42 , 17489 Greifswald , Germany
| | - Christiane A Helm
- Institute of Physics , University of Greifswald , Felix-Hausdorff-Straße 4 , 17489 Greifswald , Germany
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29
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Sun P, Huang K, Liu H. In situ study of the competitive adsorption of ions at an organic-aqueous two-phase interface: the essential role of the Hofmeister effect. SOFT MATTER 2019; 15:4346-4350. [PMID: 31074480 DOI: 10.1039/c9sm00007k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Understanding of the microcosmic essence of the competitive adsorption of different ions at liquid/liquid interfaces is of crucial importance for the elucidation of the unique chemical reactivities or selectivities of ions in numerous heterogeneous chemical processes. However, the knowledge of the microscopic mechanism behind the competitive adsorption of ions at the liquid/liquid interface is lacking. Herein, the competitive adsorption of various inorganic salt anions at organic-aqueous two-phase interfaces has been investigated as compared to that of the CrO42- ions by total internal reflection UV-visible (TIR-UV) spectroscopy since CrO42- ions are detectable by UV-visible spectroscopy and have a relatively poor interface propensity as compared to other chaotropic ions. Experimental results indicate that the interface propensities of different salt anions to the organic/aqueous phase interface follow the Hofmeister series. Molecular dynamics simulations further provided molecular-level evidence for role of the Hofmeister series of ions in the competitive adsorption of salt anions at organic-aqueous two-phase interfaces; the present study provided the first-hand experimental evidence demonstrating the occurrence of the Hofmeister series effect at the organic/aqueous two-phase interfaces, influencing the competitive adsorption of different salt ions; moreover, it is expected to offer a basis for the development of new strategies for the regulation of the chemical reactivity and selectivity of ions at organic/aqueous phase interfaces by introduction of other ions for competitive adsorption.
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Affiliation(s)
- Pan Sun
- CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China
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30
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Sun P, Huang K, Liu H. The nature of salt effect in enhancing the extraction of rare earths by non-functional ionic liquids: Synergism of salt anion complexation and Hofmeister bias. J Colloid Interface Sci 2018; 539:214-222. [PMID: 30580177 DOI: 10.1016/j.jcis.2018.12.058] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 12/12/2018] [Accepted: 12/14/2018] [Indexed: 10/27/2022]
Abstract
Separation and recycling of rare-earths using ionic liquids as extractant are becoming a promising approach to replace traditional volatile organic solvents in recent years. Generally, the addition of some special salts could improve the extraction efficiency of rare-earths by numerous non-functional ionic liquids. However, knowledge behind the nature of the salt effect is limited. Here, we found that the enhancement in the extraction of rare-earth ions, Pr3+ ions, using non-functional ionic liquid, [A336][NO3] (Tricaprylmethylammonium nitrate) was driven by the synergism of Hofmeister bias and complexation behaviors of salt anions with Pr3+ ions. Molecular dynamic simulations offered a new insight into the interaction mechanism of the ionic liquid with Pr3+ ions at liquid/liquid interface. It was revealed that salt anions could perform as a bridge to connect Pr3+ ions and the ionic liquid, so that promoted the extraction of Pr3+ ions. Therefore, the strong complexation ability of salt anions with Pr3+ ions and poor hydration of salt anions faciliated the transport of Pr3+ ions across liquid/liquid interface.
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Affiliation(s)
- Pan Sun
- CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Kun Huang
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, PR China; CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China.
| | - Huizhou Liu
- CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China
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31
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Sun P, Huang K, Liu H. Competitive Adsorption of Ions at the Oil-Water Interface: A Possible Mechanism Underlying the Separation Selectivity for Liquid-Liquid Solvent Extraction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:13155-13161. [PMID: 30346781 DOI: 10.1021/acs.langmuir.8b02691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Adsorption, especially competitive adsorption of ions at the interfaces, governs a wealth of physicochemical processes. Understanding the mechanism behind these interfacial behaviors is crucial for developing novel strategies to intensify reactions or transfer processes. Herein, as an example, we found that in the case of liquid-liquid transport of V(V) and Cr(VI) ions, the competitive adsorption of V(V) and Cr(VI) ions against coexisting SO42- ions at the oil-water interface exhibits a significant impact on the selective separation behaviors of V(V) and Cr(VI) ions. The transport of Cr(VI) ions would be hindered by adding Na2SO4 into the aqueous solutions because of the competitive adsorption of SO42- ions at the interface being stronger than that of Cr(VI) ions, whereas the transport of V(V) ions would not be affected because of the stronger affinity of V(V) ions to the interfaces compared to that of SO42- ions. The present work provides new inspirations for developing efficient strategies to improve the separation efficiency of target ions with similar physic-chemical properties by regulating their adsorption behaviors at the interface. It is beneficial to get a deeper understanding into the microscopic nature of competitive adsorption behaviors of ions at interfaces from the interface-molecular level.
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Affiliation(s)
- Pan Sun
- CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering , Chinese Academy of Sciences , Beijing 100190 , P. R. China
- University of Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Kun Huang
- CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering , Chinese Academy of Sciences , Beijing 100190 , P. R. China
- School of Metallurgical and Ecological Engineering , University of Science and Technology Beijing , Beijing 100083 , P. R. China
| | - Huizhou Liu
- CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering , Chinese Academy of Sciences , Beijing 100190 , P. R. China
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32
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Fragneto G, Delhom R, Joly L, Scoppola E. Neutrons and model membranes: Moving towards complexity. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.10.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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33
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Sun P, Huang K, Liu H. Specific Salt Effect on the Interaction between Rare Earth Ions and Trioctylphosphine Oxide Molecules at the Organic-Aqueous Two-Phase Interface: Experiments and Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11374-11383. [PMID: 30180592 DOI: 10.1021/acs.langmuir.8b02301] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding the essence of the specific salt effect on the enhancement of the transport of metal ions across the liquid/liquid interface during the process of solvent extraction is of crucial importance for the development of a new approach to extract and selectively separate various valuable metals from complex aqueous solutions. However, some abnormal experimental phenomena involved in the salt effect on the liquid/liquid solvent extraction could not be understood only from the conventional interpretation based on the salting-out ability of salt ions. The knowledge into the microscopic mechanism behind the specific salt effect was urgent. Herein, as an example, the effect of adding various salts on the extraction performance of rare earth ion Pr3+ using trioctylphosphine oxide (TOPO) as the organic extractant was investigated. It was revealed that the difference in the interface propensity of different salt anions enriched at the organic-aqueous two-phase interface played a crucial role in promoting the interaction of TOPO molecules with Pr3+ ions, despite the occurrence of the salting-out effect of those salt anions with the increase of their concentrations in aqueous solutions. The interfacial interaction mechanism obtained by molecular dynamics simulations revealed that both the interface propensity and the salting-out ability of the coexisting salt anions contributed to the enhancement in the extraction of Pr3+ into the TOPO organic phase. However, when the concentrations of coexisting salts in aqueous solutions were low enough, the extraction of Pr3+ was mainly dominated by the interface propensity of those added salt anions but not their salting-out ability. With the increase in the concentration of salts, the salting-out effect gradually became significant and, therefore, began to join with the interface propensity of salt anions to co-dominate the transport of Pr3+ ions across the liquid/liquid interface. The present study highlights the microscopic nature of the salt effect on promoting the extraction of rare earth ions and suggests that the interaction of organic extractant molecules with rare earth ions at liquid/liquid interface was dependent not only upon the salting-out ability of the coexisting salt ions but also their interface propensity.
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Affiliation(s)
- Pan Sun
- Chinese Academy of Sciences (CAS) Key Laboratory of Green Process and Engineering, Institute of Process Engineering , Chinese Academy of Sciences , Beijing 100190 , People's Republic of China
- University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Kun Huang
- Chinese Academy of Sciences (CAS) Key Laboratory of Green Process and Engineering, Institute of Process Engineering , Chinese Academy of Sciences , Beijing 100190 , People's Republic of China
- School of Metallurgical and Ecological Engineering , University of Science and Technology Beijing , 30 Xueyuan Road , Haidian, Beijing 100083 , People's Republic of China
| | - Huizhou Liu
- Chinese Academy of Sciences (CAS) Key Laboratory of Green Process and Engineering, Institute of Process Engineering , Chinese Academy of Sciences , Beijing 100190 , People's Republic of China
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34
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Wei Z, Piantavigna S, Holt SA, Nelson A, Spicer PT, Prescott SW. Comparing Surfactant Structures at "Soft" and "Hard" Hydrophobic Materials: Not All Interfaces Are Equivalent. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9141-9152. [PMID: 29999320 DOI: 10.1021/acs.langmuir.8b01686] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interfacial structures of a range of amphiphilic molecules are studied with both "soft" and "hard" hydrophobic substrates. Neutron reflection and quartz crystal microbalance with dissipation measurements highlight the differences between the adsorbed structures adopted by sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (C16TAB), and the "AM1" surface active peptide. At the soft siloxane/water interface, small molecular surfactants form loosely packed layers, with the hydrophobic tails penetrating into the oily layer, and an area per surfactant molecule that is significantly less than previously reported for the air/water interface. Neutron reflection measurements, supported by quartz crystal microbalance studies, indicate that for C16TAB, approximately 30 ± 8% of the alkyl tail penetrates into the poly(dimethylsiloxane) (PDMS) layer, whereas 20 ± 5% of the alkyl tail of SDS is located in the PDMS. For the engineered peptide surfactant AM1 (21 residues), it was found that one face of the α helix penetrated into the PDMS film. In contrast, penetration of the surfactant tails was not observed against hard solidlike hydrophobic surfaces made from octadecyltrichlorosilane (OTS) for any of the molecular species studied. At the OTS/water interface, C16TAB and SDS were seen to adsorb as larger aggregates and not as monolayers. Amphiphilic adsorption (amount, structural conformation) at the PDMS/water interface is shown to be different from that at both the air/water interface and the hard OTS/water interface, illustrating that interfacial structures cannot be predicted by the surfactant packing parameter alone. The bound PDMS layer is shown to be a useful proxy for the oil/water interface in surface and stabilization studies, with hydrophobic components of the molecules able to penetrate into the oily PDMS.
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Affiliation(s)
- Zengyi Wei
- School of Chemical Engineering , UNSW Sydney , Sydney , NSW 2052 , Australia
| | - Stefania Piantavigna
- Australian Nuclear Science and Technology Organisation , Lucas Heights , NSW 2234 , Australia
| | - Stephen A Holt
- Australian Nuclear Science and Technology Organisation , Lucas Heights , NSW 2234 , Australia
| | - Andrew Nelson
- Australian Nuclear Science and Technology Organisation , Lucas Heights , NSW 2234 , Australia
| | - Patrick T Spicer
- School of Chemical Engineering , UNSW Sydney , Sydney , NSW 2052 , Australia
| | - Stuart W Prescott
- School of Chemical Engineering , UNSW Sydney , Sydney , NSW 2052 , Australia
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35
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Corti M, Raudino A, Cantu' L, Theisen J, Pleines M, Zemb T. Nanometric Surface Oscillation Spectroscopy of Water-Poor Microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:8154-8162. [PMID: 29914260 DOI: 10.1021/acs.langmuir.8b00716] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Selectively exchanging metal complexes between emulsified water-poor microemulsions and concentrated solutions of mixed electrolytes is the core technology for strategic metal recycling. Nanostructuration triggered by solutes present in the organic phase is understood, but little is known about fluctuations of the microemulsion-water interface. We use here a modified version of an optoelectric device initially designed for air bubbles, in order to evidence resonant electrically induced surface waves of an oily droplet suspended in an aqueous phase. Resonant waves of nanometer amplitude of a millimeter-sized microemulsion droplet containing a common ion-specific extractant diluted by dodecane and suspended in a solution of rare earth nitrate are evidenced for the first time with low excitation fields (5 V/cm). From variation of the surface wave spectrum with rare earth concentration, we evidence uptake of rare-earth ions at the interface and at higher concentration the formation of a thin "crust" of liquid crystal forming at unusually low concentration, indicative of a surface induced phase transition. The effect of the liquid crystal structure on the resonance spectrum is backed up by a model, which is used to estimate crust thickness.
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Affiliation(s)
- Mario Corti
- CNR-IPCF , Viale Ferdinando Stagno d'Alcontres 37 , 98158 Messina , Italy
| | - Antonio Raudino
- Department Chemical Science , University of Catania , Viale A. Doria 6 , 95125 Catania , Italy
| | - Laura Cantu'
- Department Medical Biotechnology and Translational Medicine , University of Milano , LITA, Via Fratelli Cervi 93 , 20090 Segrate , Italy
| | - Johannes Theisen
- ICSM CEA/CNRS/UMontpellier/ENSCM, CEA Marcoule, BP17171, 30207 Bagnols-sur-Cèze , France
| | - Maximilian Pleines
- ICSM CEA/CNRS/UMontpellier/ENSCM, CEA Marcoule, BP17171, 30207 Bagnols-sur-Cèze , France
| | - Thomas Zemb
- ICSM CEA/CNRS/UMontpellier/ENSCM, CEA Marcoule, BP17171, 30207 Bagnols-sur-Cèze , France
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Protat M, Bodin-Thomazo N, Malloggi F, Daillant J, Campbell RA, Fragneto G, Watkins EB, Perrin P, Pantoustier N, Guenoun P. Neutron reflectivity measurements at the oil/water interface for the study of stimuli-responsive emulsions ⋆. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:85. [PMID: 30003353 DOI: 10.1140/epje/i2018-11693-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
Stable stimuli-responsive emulsions between oil and water are formed with an amphiphilic block copolymer bearing polystyrene (PS) and poly(dimethylaminoethyl methacrylate) (PDMAEMA) moieties. Different kinds of emulsions like direct, multiple or inverse ones are reproducibly formed as a function of chemical parameters such as p H and salt concentration. To test the correlation between the different nature of the emulsion and the conformation of the polymer chain at the interface, neutron reflectometry at the oil/water interface was carried out. An original sample cell was built and the procedure to get reliable results with it on the FIGARO reflectometer at the Institut Laue-Langevin is described. Results show that for direct emulsions, the copolymer is much more extended on the water side than on the oil side. In the case where multiple emulsions are stabilized, the conformation is strongly modified and is compatible with a more equilibrated extension of the chain on both sides. The inverse case shows that the extension in oil is stronger than in water. These results are discussed in term of polymer brushes (charged or neutral) extension with respect to salt addition and hydrophobic interactions.
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Affiliation(s)
- M Protat
- LIONS, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191, Gif-sur-Yvette Cedex, France
| | - N Bodin-Thomazo
- LIONS, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191, Gif-sur-Yvette Cedex, France
| | - F Malloggi
- LIONS, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191, Gif-sur-Yvette Cedex, France
| | - J Daillant
- Synchrotron Soleil, L' Orme des Merisiers, Saint-Aubin, BP 48, 91192, Gif-sur-Yvette Cedex, France
| | - R A Campbell
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042, Grenoble, France
- Division of Pharmacy and Optometry, University of Manchester, M13 9PT, Manchester, UK
| | - G Fragneto
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042, Grenoble, France
| | - E B Watkins
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042, Grenoble, France
| | - P Perrin
- Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL University, Sorbonne-Université, CNRS, 10 rue Vauquelin, 75005, Paris, France
| | - N Pantoustier
- Sciences et Ingénierie de la Matière Molle, ESPCI Paris, PSL University, Sorbonne-Université, CNRS, 10 rue Vauquelin, 75005, Paris, France
| | - P Guenoun
- LIONS, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191, Gif-sur-Yvette Cedex, France.
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Kim JY, Morisada S, Kawakita H, Ohto K. Comparison of interfacial behavior and silver extraction kinetics with various types calix[4]arene derivatives at heterogeneous liquid-liquid interfaces. J Chromatogr A 2018; 1558:107-114. [DOI: 10.1016/j.chroma.2018.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 11/24/2022]
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Abstract
During solvent extraction, amphiphilic extractants assist the transport of metal ions across the liquid-liquid interface between an aqueous ionic solution and an organic solvent. Investigations of the role of the interface in ion transport challenge our ability to probe fast molecular processes at liquid-liquid interfaces on nanometer-length scales. Recent development of a thermal switch for solvent extraction has addressed this challenge, which has led to the characterization by X-ray surface scattering of interfacial intermediate states in the extraction process. Here, we review and extend these earlier results. We find that trivalent rare earth ions, Y(III) and Er(III), combine with bis(hexadecyl) phosphoric acid (DHDP) extractants to form inverted bilayer structures at the interface; these appear to be condensed phases of small ion-extractant complexes. The stability of this unconventional interfacial structure is verified by molecular dynamics simulations. The ion-extractant complexes at the interface are an intermediate state in the extraction process, characterizing the moment at which ions have been transported across the aqueous-organic interface, but have not yet been dispersed in the organic phase. In contrast, divalent Sr(II) forms an ion-extractant complex with DHDP that leaves it exposed to the water phase; this result implies that a second process that transports Sr(II) across the interface has yet to be observed. Calculations demonstrate that the budding of reverse micelles formed from interfacial Sr(II) ion-extractant complexes could transport Sr(II) across the interface. Our results suggest a connection between the observed interfacial structures and the extraction mechanism, which ultimately affects the extraction selectivity and kinetics.
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Kusaka R, Watanabe M. The structure of a lanthanide complex at an extractant/water interface studied using heterodyne-detected vibrational sum frequency generation. Phys Chem Chem Phys 2018; 20:2809-2813. [DOI: 10.1039/c7cp06758e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Eu3+ at an extractant/water interface is bound to extractants from the upper side and to water molecules from the lower side, and forms a unique interfacial complex.
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Affiliation(s)
- Ryoji Kusaka
- Nuclear Science and Engineering Center
- Japan Atomic Energy Agency (JAEA)
- 2-4 Shirakata
- Tokai
- Japan
| | - Masayuki Watanabe
- Nuclear Science and Engineering Center
- Japan Atomic Energy Agency (JAEA)
- 2-4 Shirakata
- Tokai
- Japan
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Zhou T, McCue A, Ghadar Y, Bakó I, Clark AE. Structural and Dynamic Heterogeneity of Capillary Wave Fronts at Aqueous Interfaces. J Phys Chem B 2017; 121:9052-9062. [PMID: 28871781 DOI: 10.1021/acs.jpcb.7b07406] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using a unique combination of slab-layering analyses and identification of truly interfacial molecules, this work examines water/vapor and water/n-hexane interfaces, specifically the structural and dynamic perturbations of the interfacial water molecules at different locations within the surface capillary waves. From both the structural and dynamic properties analyzed, it is found that these interfacial water molecules dominate the perturbations within the interfacial region, which can extend deep into the water phase relative to the Gibbs dividing surface. Of more importance is the demonstration of structural and dynamic heterogeneity of the interfacial water molecules at the capillary wave front, as indicated by the dipole orientation and the structural and dynamic behavior of hydrogen bonds and their networks.
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Affiliation(s)
- Tiecheng Zhou
- Department of Chemistry and the Materials Science and Engineering Program, Washington State University , Pullman, 99164-2920 Washington, United States
| | - Alex McCue
- Department of Chemistry and the Materials Science and Engineering Program, Washington State University , Pullman, 99164-2920 Washington, United States
| | - Yasaman Ghadar
- Department of Chemistry and the Materials Science and Engineering Program, Washington State University , Pullman, 99164-2920 Washington, United States
| | - Imre Bakó
- Institute of Organic Chemistry Research Centre for Natural Sciences, Hungarian Academy of Sciences , Magyar Tudosók Körútja 2, P.O. Box 286, 1519 Budapest, Hungary
| | - Aurora E Clark
- Department of Chemistry and the Materials Science and Engineering Program, Washington State University , Pullman, 99164-2920 Washington, United States
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Braun L, Uhlig M, von Klitzing R, Campbell RA. Polymers and surfactants at fluid interfaces studied with specular neutron reflectometry. Adv Colloid Interface Sci 2017; 247:130-148. [PMID: 28822539 DOI: 10.1016/j.cis.2017.07.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/08/2017] [Indexed: 01/18/2023]
Abstract
This review addresses the advances made with specular neutron reflectometry in studies of aqueous mixtures of polymers and surfactants at fluid interfaces during the last decade (or so). The increase in neutron flux due to improvements in instrumentation has led to routine measurements at the air/water interface that are faster and involve samples with lower isotopic contrast than in previous experiments. One can now resolve the surface excess of a single deuterated component on the second time scale and the composition of a mixture on the minute time scale, and information about adsorption processes and dynamic rheology can also be accessed. Research areas addressed include the types of formed equilibrium surface structures, the link to foam film stability and the range of non-equilibrium effects that dominate the behavior of oppositely charged polyelectrolyte/surfactant mixtures, macroscopic film formation in like-charged polymer/surfactant mixtures, and the properties of mixtures of bio-polymers with surfactants and lipids.
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