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Gallo T, Adriano L, Heymann M, Wrona A, Walsh N, Öhrwall G, Callefo F, Skruszewicz S, Namboodiri M, Marinho R, Schulz J, Valerio J. Development of a flat jet delivery system for soft X-ray spectroscopy at MAX IV. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:1285-1292. [PMID: 39172090 PMCID: PMC11371042 DOI: 10.1107/s1600577524006611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 07/04/2024] [Indexed: 08/23/2024]
Abstract
One of the most challenging aspects of X-ray research is the delivery of liquid sample flows into the soft X-ray beam. Currently, cylindrical microjets are the most commonly used sample injection systems for soft X-ray liquid spectroscopy. However, they suffer from several drawbacks, such as complicated geometry due to their curved surface. In this study, we propose a novel 3D-printed nozzle design by introducing microscopic flat sheet jets that provide micrometre-thick liquid sheets with high stability, intending to make this technology more widely available to users. Our research is a collaboration between the EuXFEL and MAX IV research facilities. This collaboration aims to develop and refine a 3D-printed flat sheet nozzle design and a versatile jetting platform that is compatible with multiple endstations and measurement techniques. Our flat sheet jet platform improves the stability of the jet and increases its surface area, enabling more precise scanning and differential measurements in X-ray absorption, scattering, and imaging applications. Here, we demonstrate the performance of this new arrangement for a flat sheet jet setup with X-ray photoelectron spectroscopy, photoelectron angular distribution, and soft X-ray absorption spectroscopy experiments performed at the photoemission endstation of the FlexPES beamline at MAX IV Laboratory in Lund, Sweden.
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Affiliation(s)
| | | | | | | | | | | | - Flavia Callefo
- Brazilian Synchrotron Light Laboratory, LNLSBrazilian Center for Research in Energy and Materials (CPNEM)Brazil
| | | | | | - Ricardo Marinho
- Institute of Physics, Brasilia University (UnB), 70.919-970Brasília, Brazil
- Institute of Physics Federal University of Bahia40.170-115SalvadorBrazil
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2
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Xie C, Xiao Y, He C, Liu WS, Tang YT, Wang S, van der Ent A, Morel JL, Simonnot MO, Qiu RL. Selective recovery of rare earth elements and value-added chemicals from the Dicranopteris linearis bio-ore produced by agromining using green fractionation. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130253. [PMID: 36327843 DOI: 10.1016/j.jhazmat.2022.130253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/24/2022] [Accepted: 10/22/2022] [Indexed: 06/16/2023]
Abstract
The increasing demand for Rare Earth Elements (REEs) and the depletion of mineral resources motivate sustainable strategies for REE recovery from alternative unconventional sources, such as REE hyperaccumulator. The greatest impediment to REE agromining is the difficulty in the separation of REEs and other elements from the harvested biomass (bio-ore). Here, we develop a sulfuric acid assisted ethanol fractionation method for processing D. linearis bio-ore to produce the pure REE compounds and value-added chemicals. The results show that 94.5% of REEs and 87.4% of Ca remained in the solid phase, and most of the impurities (Al, Fe, Mg, and Mn) transferred to the liquid phase. Density functional theory calculations show that the water-cation bonds of REEs and Ca cations were broken more easily than the bonds of the cations of key impurities, causing lower solubility of REEs and Ca compounds. Subsequent separation and purification led to a REE-oxide (REO) product with a purity of 97.1% and a final recovery of 88.9%. In addition, lignin and phenols were obtained during organosolv fractionation coupled with a fast pyrolysis process. This new approach opens up the possibility for simultaneous selective recovery of REEs and to produce value-added chemicals from REE bio-ore refining.
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Affiliation(s)
- Candie Xie
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Ye Xiao
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Chao He
- Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland
| | - Wen-Shen Liu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
| | - Ye-Tao Tang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Shizhong Wang
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
| | - Antony van der Ent
- Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, St Lucia, Queensland 4072, Australia
| | | | | | - Rong-Liang Qiu
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
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3
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Ågren H, Björneholm O, Öhrwall G, Carravetta V, de Brito AN. Ethanol in Aqueous Solution Studied by Microjet Photoelectron Spectroscopy and Theory. Acc Chem Res 2022; 55:3080-3087. [PMID: 36251058 DOI: 10.1021/acs.accounts.2c00471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
By combining results and analysis from cylindrical microjet photoelectron spectroscopy (cMJ-PES) and theoretical simulations, we unravel the microscopic properties of ethanol-water solutions with respect to structure and intermolecular bonding patterns following the full concentration scale from 0 to 100% ethanol content. In particular, we highlight the salient differences between bulk and surface. Like for the pure water and alcohol constituents, alcohol-water mixtures have attracted much interest in applications of X-ray spectroscopies owing to their potential of combining electronic and geometric structure probing. The water mixtures of the two simplest alcohols, methanol and ethanol, have generated particular attention due to their delicate hydrogen bonding networks that underlie their structural and thermodynamic properties. Macroscopically ethanol-water seems to mix very well, however microscopically this is not true. The aberrant thermodynamics of water-alcohol mixtures have been suggested to be caused by energy differences of hydrogen bonding between water-water, alcohol-alcohol and alcohol-water molecules. These networks may perturb the local character of the interaction between X-rays and matter, calling for analysis that go beyond the normally applied local selection and building block rules and that can combine the effects of light-matter, intra- and intermolecular interactions. However, despite decades of ongoing research there are still controversies of the precise nature of hydrogen bonding networks that underlie the mixing of these simple molecules. Our combined analysis indicates that at low concentration ethanol molecules form a film at the surface since ethanol at the surface can expose its hydrophobic part to the vacuum retaining its two (or three) possible hydrogen bonds, while water at the surface cannot retain all its four possible hydrogen bonds. Thus, ethanol at the surface becomes energetically favorable. Ethanol molecules show a tilting angle variation of the C-C axis with respect to the surface normal as large as 60° at very low concentration. In bulk, around ca. ten %, the ethanol oxygen atoms tend to make a third acceptor hydrogen bond to water molecules. At ca. 20 %, there is a U-shaped change in the CH3 to CH2OH binding energy (BE) shift indicating the presence of ring-like agglomerates called clathrate structures. At the surface, between 5 and 25%, ethanol forms a closely packed layer with the smallest C-C tilting angle variation down to ∼20°. Above 25% and below the azeotrope at the surface, ethanol shows an increase in the tilting angle variation, while at very high ethanol concentrations water tends to move to the surface so giving a microscopic explanation of the azeotrope effect. This migration is connected to the presence of longer (shorter) ethanol chains in the bulk (surface). A brief comparison with discussions and predictions from other spectroscopic techniques is also given. We emphasize the execution of an integrated approach that combines molecular structural dynamics with quantum predictions of the core electronic chemical shift, so establishing a protocol with considerable interpretative as well as predictive power for cMJ-PES measurements. We believe that this protocol can valorize cMJ-PES for studies of properties of other alcohol mixtures as well as of binary solutions in general.
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Affiliation(s)
- Hans Ågren
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Olle Björneholm
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Gunnar Öhrwall
- MAX IV Laboratory, Lund University, Box 118, SE-22100 Lund, Sweden
| | - Vincenzo Carravetta
- CNR-IPCF, Institute of Chemical Physical Processes, via G.Moruzzi 1, I-56124 Pisa, Italy
| | - Arnaldo Naves de Brito
- Department of Applied Physics, Institute of Physics "Gleb Wataghin", Campinas University, CEP 13083859 Campinas SP, Brazil
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4
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Carravetta V, Gomes AHDA, Marinho RDRT, Öhrwall G, Ågren H, Björneholm O, de Brito AN. An atomistic explanation of the ethanol-water azeotrope. Phys Chem Chem Phys 2022; 24:26037-26045. [PMID: 36268753 DOI: 10.1039/d2cp03145k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ethanol and water form an azeotropic mixture at an ethanol molecular percentage of ∼91% (∼96% by volume), which prohibits ethanol from being further purified via distillation. Aqueous solutions at different concentrations in ethanol have been studied both experimentally and theoretically. We performed cylindrical micro-jet photoelectron spectroscopy, excited by synchrotron radiation, 70 eV above C1s ionization threshold, providing optimal atomic-scale surface-probing. Large model systems have been employed to simulate, by molecular dynamics, slabs of the aqueous solutions and obtain an atomistic description of both bulk and surface regions. We show how the azeotropic behaviour results from an unexpected concentration-dependence of the surface composition. While ethanol strongly dominates the surface and water is almost completely depleted from the surface for most mixing ratios, the different intermolecular bonding patterns of the two components cause water to penetrate to the surface region at high ethanol concentrations. The addition of surface water increases its relative vapour pressure, giving rise to the azeotropic behaviour.
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Affiliation(s)
- Vincenzo Carravetta
- CNR-IPCF, Institute of Chemical and Physical Processes, via G. Moruzzi 1, I-56124 Pisa, Italy.
| | - Anderson Herbert de Abreu Gomes
- Dept. of Applied Physics, Institute of Physics "Gleb Wataghin", Campinas University, CEP: 13083-859 Campinas, SP, Brazil. .,Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research on Energy and Materials (CNPEM), PO Box 6192, 13083-970, Campinas, SP, Brazil
| | - Ricardo Dos Reis Teixeira Marinho
- Institute of Physics, Federal University of Bahia, 40.170-115, Salvador, BA, Brazil.,Institute of Physics, Brasilia University (UnB), 70.919-970, Brasília, Brazil
| | - Gunnar Öhrwall
- MAX IV Laboratory, Lund University, Box 118, SE-22100 Lund, Sweden
| | - Hans Ågren
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Olle Björneholm
- Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Arnaldo Naves de Brito
- Dept. of Applied Physics, Institute of Physics "Gleb Wataghin", Campinas University, CEP: 13083-859 Campinas, SP, Brazil.
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5
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Nagasaka M, Bouvier M, Yuzawa H, Kosugi N. Hydrophobic Cluster Formation in Aqueous Ethanol Solutions Probed by Soft X-ray Absorption Spectroscopy. J Phys Chem B 2022; 126:4948-4955. [PMID: 35748647 DOI: 10.1021/acs.jpcb.2c02990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hydrophobic cluster structures in aqueous ethanol solutions at different concentrations have been investigated by soft X-ray absorption spectroscopy (XAS). In the O K-edge XAS, we have found that hydrogen bond structures among water molecules are enhanced in the middle-concentration region by the hydrophobic interaction of the ethyl groups in ethanol. In the C K-edge XAS, the lower energy features arise from a transition from the terminal methyl C 1s electron to an unoccupied orbital of 3s Rydberg character, which is sensitive to the nearest-neighbor intermolecular interactions. From the comparison of C K-edge XAS with the inner-shell calculations, we have found that ethanol clusters are easily formed in the middle-concentration region due to the hydrophobic interaction of the ethyl group in ethanol, resulting in the enhancement of the hydrogen bond structures among water molecules. This behavior is different from aqueous methanol solutions, where the methanol-water mixed clusters are more predominant in the middle-concentration region due to the relatively weak hydrophobic interactions of the methyl group in methanol.
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Affiliation(s)
- Masanari Nagasaka
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki 444-8585, Japan
| | - Mathilde Bouvier
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Hayato Yuzawa
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
| | - Nobuhiro Kosugi
- Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki 444-8585, Japan
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6
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Reese T, Suarez C, Premasiri WR, Shaine ML, Ingraham H, Brodeur AN, Ziegler LD. Surface enhanced Raman scattering specificity for detection and identification of dried bloodstains. Forensic Sci Int 2021; 328:111000. [PMID: 34564021 DOI: 10.1016/j.forsciint.2021.111000] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 08/16/2021] [Accepted: 09/10/2021] [Indexed: 01/20/2023]
Abstract
Surface enhanced Raman spectroscopy (SERS) provides highly specific vibrational signatures identifying dried blood for a variety of forensic applications. SERS spectra on Au nanoparticle substrates excited at 785 nm are found to identify dried stains of human and nonhuman blood from seven animals, and distinguish stains due to menstrual and peripheral blood. In addition, the unique SERS bloodstain spectrum is distinct from the SERS spectra of thirty red-brown stains of potential household substances that could be visually mistaken for bloodstains and from food stains that have been shown to give positive results with presumptive colorimetric blood tests. Finally, a SERS swab procedure has been developed and demonstrates that the substrates that a blood sample dried on does not offer any Raman or fluorescence interference for the SERS identification of dried blood. Such bloodstains on porous and nonporous materials are all identical and exclusively due to the heme moiety of hemoglobin. Optimized selection of the extraction solvent is found to control the chemical composition of molecular components appearing in the SERS spectrum of complex, multicomponent biological mixtures, such as body fluids.
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Affiliation(s)
- T Reese
- Program in Biomedical Forensic Sciences, Boston University School of Medicine, Boston, MA 02118, USA
| | - C Suarez
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA 02215, USA
| | - W R Premasiri
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA 02215, USA; Photonics Center, Boston University, 15 Saint Mary's St., Boston, MA 02215, USA
| | - M L Shaine
- Program in Biomedical Forensic Sciences, Boston University School of Medicine, Boston, MA 02118, USA
| | - H Ingraham
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA 02215, USA; Photonics Center, Boston University, 15 Saint Mary's St., Boston, MA 02215, USA
| | - A N Brodeur
- Program in Biomedical Forensic Sciences, Boston University School of Medicine, Boston, MA 02118, USA
| | - L D Ziegler
- Department of Chemistry, Boston University, 590 Commonwealth Ave., Boston, MA 02215, USA; Photonics Center, Boston University, 15 Saint Mary's St., Boston, MA 02215, USA.
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7
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Ekholm V, Caleman C, Hub JS, Wohlert M. Propensity, free energy contributions and conformation of primary n-alcohols at a water surface. Phys Chem Chem Phys 2021; 23:18823-18829. [PMID: 34612420 DOI: 10.1039/d1cp02818a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atmospheric aerosols contain organic molecules that serve as cloud condensation nucleation sites and affect the climate. Several experimental and simulation studies have been dedicated to investigate their surface propensity, but the mechanisms that drive them to the water surface are still not fully understood. In this molecular dynamics (MD) simulation study, primary alcohols are considered as a model system representing polar organic molecules. We find that the surface affinity of n-alcohols increases linearly with the length of the hydrophobic tail. By decomposing the adsorption free energy into enthalpy and entropy contributions, we find that the transition from bulk to surface is entropically driven, compatible with the fact that the hydrophobic effect of small solutes is of entropic origin. The enthalpy of surface adsorption is nearly invariant among different n-alcohols because the loss of solvent-alcohol interactions is balanced by a gain in solvent-solvent interactions. Structural analysis shows that, at the surface, the linear alcohols prefer an orientation with the hydrophobic tail pointing out from the surface, whereas the hydroxyl group remains buried in the water. This general behaviour is likely transferable to other small molecules with similar structures but other functional groups that are present in the atmosphere. Therefore, the present study is a step forward toward a general description of organic molecules in aerosols.
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8
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Weeraratna C, Amarasinghe C, Lu W, Ahmed M. A Direct Probe of the Hydrogen Bond Network in Aqueous Glycerol Aerosols. J Phys Chem Lett 2021; 12:5503-5511. [PMID: 34087076 DOI: 10.1021/acs.jpclett.1c01383] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The properties of aerosols are of paramount importance in atmospheric chemistry and human health. The hydrogen bond network of glycerol-water aerosols generated from an aqueous solution with different mixing ratios is probed directly with X-ray photoelectron spectroscopy. The carbon and oxygen X-ray spectra reveal contributions from gas and condensed phase components of the aerosol. It is shown that water suppresses glycerol evaporation up to a critical mixing ratio. A dielectric analysis using terahertz spectroscopy coupled with infrared spectroscopy of the bulk solutions provides a picture of the microscopic heterogeneity prevalent in the hydrogen bond network when combined with the photoelectron spectroscopy analysis. The hydrogen bond network is composed of three intertwined regions. At low concentrations, glycerol molecules are surrounded by water forming a solvated water network. Adding more glycerol leads to a confined water network, maximizing at 22 mol %, beyond which the aerosol resembles bulk glycerol. This microscopic view of hydrogen bonding networks holds promise in probing evaporation, diffusion dynamics, and reactivity in aqueous aerosols.
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Affiliation(s)
- Chaya Weeraratna
- Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Chandika Amarasinghe
- Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Wenchao Lu
- Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Musahid Ahmed
- Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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9
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Kirschner J, Gomes AHA, Marinho RRT, Björneholm O, Ågren H, Carravetta V, Ottosson N, Brito AND, Bakker HJ. The molecular structure of the surface of water-ethanol mixtures. Phys Chem Chem Phys 2021; 23:11568-11578. [PMID: 33977931 DOI: 10.1039/d0cp06387h] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mixtures of water and alcohol exhibit an excess surface concentration of alcohol as a result of the amphiphilic nature of the alcohol molecule, which has important consequences for the physico-chemical properties of water-alcohol mixtures. Here we use a combination of intensity vibrational sum-frequency generation (VSFG) spectroscopy, heterodyne-detected VSFG (HD-VSFG), and core-level photoelectron spectroscopy (PES) to investigate the molecular properties of water-ethanol mixtures at the air-liquid interface. We find that increasing the ethanol concentration up to a molar fraction (MF) of 0.1 leads to a steep increase of the surface density of the ethanol molecules, and an increased ordering of the ethanol molecules at the surface. When the ethanol concentration is further increased, the surface density of ethanol remains more or less constant, while the orientation of the ethanol molecules becomes increasingly disordered. The used techniques of PES and VSFG provide complementary information on the density and orientation of ethanol molecules at the surface of water, thus providing new information on the molecular-scale properties of the surface of water-alcohol mixtures over a wide range of compositions. This information is invaluable in understanding the chemical and physical properties of water-alcohol mixtures.
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Affiliation(s)
- Johannes Kirschner
- Ultrafast Spectroscopy, AMOLF, 1098 XG Science Park, Amsterdam, The Netherlands.
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10
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Thürmer S, Shinno T, Suzuki T. Valence Photoelectron Spectra of Liquid Methanol and Ethanol Measured Using He II Radiation. J Phys Chem A 2021; 125:2492-2503. [PMID: 33755491 DOI: 10.1021/acs.jpca.1c00288] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
High-resolution photoelectron (PE) spectra of liquid methanol and ethanol were measured using a liquid microjet and He IIα radiation (40.813 eV). The vertical ionization energy and the ionization threshold were determined as 9.70 ± 0.07 and 8.69 ± 0.07 eV for methanol and 9.52 ± 0.07 and 8.52 ± 0.07 eV for ethanol, respectively. Individual photoemission bands observed for the liquids are well correlated with those in PE spectra of the gaseous samples also measured in the present study, except that the liquid band positions were shifted on average by -1.23 eV for methanol and -1.10 eV for ethanol as compared to the gas. The 5a' and 7a' bands of liquid methanol exhibit specifically larger broadening than other bands, for which we attempted spectral fitting with two components, similarly with the case of the 3a1 band of liquid water. PE spectra of both liquid and gaseous ethanol are congested partly due to the presence of the trans and gauche isomers; however, the overall band positions are generally in good agreement with predictions based on quantum chemical calculations. Comparison of the measured PE spectra with experimental and simulated X-ray emission spectra indicate that spectral differences in the lowest ionization band of both methanol and ethanol originate from involvement of nuclear dynamics in the X-ray emission process.
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Affiliation(s)
- Stephan Thürmer
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto 606-8501, Japan
| | - Takatoshi Shinno
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto 606-8501, Japan
| | - Toshinori Suzuki
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto 606-8501, Japan
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11
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Chacón KN, Espinal JF, Montero-Campillo MM, Yáñez M, Mejía SM. Looking for the Azeotrope: A Computational Study of (Ethanol) 6-Water, (Methanol) 6-Water, (Ethanol) 7, and (Methanol) 7 Heptamers. J Phys Chem A 2020; 124:7080-7087. [PMID: 32786982 DOI: 10.1021/acs.jpca.0c05362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Considering that a molecular-level understanding of the azeotropic ethanol-water system can contribute to the search of new methodologies and/or modifications of industrial separation methods, this study tries to provide some clues to understand why azeotropes should be expected for ethanol, but not for methanol. Our exploration of the potential energy surface of (ethanol)6-water heteroheptamers, carried out at the B3LYP-D3/6-311++G(d,p) level, shows these heteroclusters to exhibit a cyclic structure where the cooperativity effects between the OH···O HBs is a fundamental ingredient. An analysis of this cooperativity clearly indicates that ethanol-water systems will exhibit a similarly high stability as the heterocluster size approaches the azeotrope. However, a similar behavior should not be expected for the methanol-containing analogues. A comparison between (ethanol)7, (ethanol)6-water, (methanol)7, and (methanol)6-water shows the ethanol-containing systems to be significantly more stable than the methanol-containing analogues. This result is probably due to the fact that the OH···O HBs are weaker than those found between ethanol molecules. However, our atoms in molecule (AIM) and noncovalent interaction (NCI) analyses unambiguously show that important contributors to the enhanced stability of the ethanol-containing clusters are the secondary van der Waals interactions between ethyl groups, which are not observed between methyl groups. Hence, while the formation of stable azeotropes is expected for the case of ethanol, for the methanol-containing analogues, the relative stability of the clusters is significantly smaller, and its formation is accompanied by an increase of the free energy.
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Affiliation(s)
- Kevin N Chacón
- Línea de Investigación en Química Computacional, Grupo de Investigación GIFUJ, Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, 110231 Bogotá, Colombia
| | - Juan F Espinal
- Química de Recursos Energéticos y MedioAmbiente, Instituto de Química, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, 050010 Medellín, Colombia
| | - M Merced Montero-Campillo
- Departamento de Química, Módulo 13, Facultad de Ciencias and Institute of Advanced Chemical Sciences (IadChem), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Manuel Yáñez
- Departamento de Química, Módulo 13, Facultad de Ciencias and Institute of Advanced Chemical Sciences (IadChem), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Sol M Mejía
- Línea de Investigación en Química Computacional, Grupo de Investigación GIFUJ, Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, 110231 Bogotá, Colombia
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12
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Carravetta V, de Abreu Gomes AH, Monti S, Mocellin A, Marinho RRT, Björneholm O, Ågren H, Naves de Brito A. pH-dependent X-ray Photoelectron Chemical Shifts and Surface Distribution of Cysteine in Aqueous Solution. J Phys Chem B 2019; 123:3776-3785. [PMID: 30964991 DOI: 10.1021/acs.jpcb.9b00866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The distribution and protonation states of amino acids in water droplets are of considerable concern in studies on the formation of clouds in the atmosphere as well as in many biological contexts. In the present work we use the amino acid cysteine as a prototypical example and explore the protonation states of this molecule in aqueous solution, which are strongly affected by the acidity of the environment and also can show different distributions between surface and bulk. We use a combination of X-ray photoelectron chemical shift measurements, density functional theory calculations of the shifts, and reactive force field molecular dynamics simulations of the underlying structural dynamics. We explore how the photoelectron spectra distinctly reflect the different protonation states that are generated by variation of the solution acidity and how the distribution of these protonation states can differ between bulk and surface regions. At specific pH values, we find that the distribution of the cysteine species at the surface is quite different from that in bulk, in particular, for the appearance in the surface region of species which do not exist in bulk. Some ramifications of this finding are discussed.
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Affiliation(s)
- Vincenzo Carravetta
- Institute of Chemical and Physical Processes , CNR-IPCF , via G. Moruzzi 1 , I-56124 Pisa , Italy
| | - Anderson Herbert de Abreu Gomes
- Department of Applied Physics, Institute of Physics "Gleb Wataghin" , University of Campinas , 13.083-859 Campinas , SP , Brazil
| | - Susanna Monti
- Institute of Chemistry of Organometallic Compounds , CNR-ICCOM , via G. Moruzzi 1 , I-56124 Pisa , Italy
| | - Alexandra Mocellin
- Institute of Physics , Brasilia University , Box 4455, Brasília 70910-970 , Brazil
| | - Ricardo R T Marinho
- Institute of Physics , Brasilia University , Box 4455, Brasília 70910-970 , Brazil.,Institute of Physics , Federal University of Bahia , 40.170-115 , Salvador , BA , Brazil
| | - Olle Björneholm
- Department of Physics and Astronomy , Uppsala University , 752 36 Uppsala , Sweden
| | - Hans Ågren
- Department of Physics and Astronomy , Uppsala University , 752 36 Uppsala , Sweden.,Theoretical Chemistry and Biology, School of Chemistry, Biotechnology and Health, KTH Royal Institute of Technology , SE-10044 Stockholm , Sweden
| | - Arnaldo Naves de Brito
- Department of Applied Physics, Institute of Physics "Gleb Wataghin" , University of Campinas , 13.083-859 Campinas , SP , Brazil
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