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Sloutskin E, Tamam L, Sapir Z, Ocko BM, Bain CD, Kuzmenko I, Gog T, Deutsch M. Counterions under a Surface-Adsorbed Cationic Surfactant Monolayer: Structure and Thermodynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:12356-12366. [PMID: 36170153 DOI: 10.1021/acs.langmuir.2c02076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The surface adsorption of ionic surfactants is fundamental for many widespread phenomena in life sciences and for a wide range of technological applications. However, direct atomic-resolution structural experimental studies of noncrystalline surface-adsorbed films are scarce. Thus, even the most central physical aspects of these films, such as their charge density, remain uncertain. Consequently, theoretical models based on contradicting assumptions as for the surface films' ionization are widely used for the description and prediction of surface thermodynamics. We employ X-ray reflectivity to obtain the Ångström-scale surface-normal structure of surface-adsorbed films of the cationic surfactant cetyltrimethylammonium bromide (CTAB) in aqueous solutions at several different temperatures and concentrations. In conjunction with published neutron reflectivity data, we determine the surface-normal charge distribution due to the dissociated surfactants' headgroups. The distribution appears to be inconsistent with the Gouy-Chapman model yet consistent with a compact Stern layer model of condensed counterions. The experimental surfactant adsorption thermodynamics conforms well to classical, Langmuir and Kralchevsky, adsorption models. Furthermore, the Kralchevsky model correctly reproduces the observed condensation of counterions, allowing the values of the adsorption parameters to be resolved, based on the combination of the present data and the published surface tension measurements.
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Affiliation(s)
- Eli Sloutskin
- Physics Department and Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Lilach Tamam
- Physics Department and Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Zvi Sapir
- Physics Department and Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Benjamin M Ocko
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Colin D Bain
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | - Ivan Kuzmenko
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Thomas Gog
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Moshe Deutsch
- Physics Department and Bar-Ilan Institute of Nanotechnology & Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
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2
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Gregory KP, Elliott GR, Robertson H, Kumar A, Wanless EJ, Webber GB, Craig VSJ, Andersson GG, Page AJ. Understanding specific ion effects and the Hofmeister series. Phys Chem Chem Phys 2022; 24:12682-12718. [PMID: 35543205 DOI: 10.1039/d2cp00847e] [Citation(s) in RCA: 73] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Specific ion effects (SIE), encompassing the Hofmeister Series, have been known for more than 130 years since Hofmeister and Lewith's foundational work. SIEs are ubiquitous and are observed across the medical, biological, chemical and industrial sciences. Nevertheless, no general predictive theory has yet been able to explain ion specificity across these fields; it remains impossible to predict when, how, and to what magnitude, a SIE will be observed. In part, this is due to the complexity of real systems in which ions, counterions, solvents and cosolutes all play varying roles, which give rise to anomalies and reversals in anticipated SIEs. Herein we review the historical explanations for SIE in water and the key ion properties that have been attributed to them. Systems where the Hofmeister series is perturbed or reversed are explored, as is the behaviour of ions at the liquid-vapour interface. We discuss SIEs in mixed electrolytes, nonaqueous solvents, and in highly concentrated electrolyte solutions - exciting frontiers in this field with particular relevance to biological and electrochemical applications. We conclude the perspective by summarising the challenges and opportunities facing this SIE research that highlight potential pathways towards a general predictive theory of SIE.
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Affiliation(s)
- Kasimir P Gregory
- Discipline of Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia. .,Department of Materials Physics, Research School of Physics, Australian National University, Canberra, ACT 0200, Australia
| | - Gareth R Elliott
- Discipline of Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia.
| | - Hayden Robertson
- Discipline of Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia.
| | - Anand Kumar
- Flinders Institute of Nanoscale Science and Technology, College of Science and Engineering, Flinders University, South Australia 5001, Australia
| | - Erica J Wanless
- Discipline of Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia.
| | - Grant B Webber
- School of Engineering, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Vincent S J Craig
- Department of Materials Physics, Research School of Physics, Australian National University, Canberra, ACT 0200, Australia
| | - Gunther G Andersson
- Flinders Institute of Nanoscale Science and Technology, College of Science and Engineering, Flinders University, South Australia 5001, Australia
| | - Alister J Page
- Discipline of Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia.
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3
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Kumar A, Craig VS, Page AJ, Webber GB, Wanless EJ, Andersson G. Ion Specificity in the Measured Concentration Depth Profile of Ions at the Vapor-Glycerol Interface. J Colloid Interface Sci 2022; 626:687-699. [DOI: 10.1016/j.jcis.2022.06.104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/04/2022] [Accepted: 06/21/2022] [Indexed: 10/31/2022]
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4
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Adel T, Ng KC, Vazquez de Vasquez MG, Velez-Alvarez J, Allen HC. Insight into the Ionizing Surface Potential Method and Aqueous Sodium Halide Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:7863-7874. [PMID: 34152764 DOI: 10.1021/acs.langmuir.1c00465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Complementing the microscopic picture of the surface structure of electrolyte solutions set out by previous theoretical and experimental studies, the ionizing surface potential technique offers a unique approach to quantifying the impact of aqueous inorganic ions upon the interfacial electric field of the air-aqueous interface. In this Feature Article, we review the vulnerability of theoretical and empirically derived χwater values as a normative reference for aqueous ion surface potentials. Instead, we recognize and evaluate aqueous ion surface potentials relative to well-known ionic surfactants cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). Additionally, we also explore factors that impact the magnitude of the measured surface potentials using the ionizing method, particularly in the type of reference electrode and ionizing gas environment. With potential measurements of sodium halide solutions, we show that iodide has a dominant effect on the air-aqueous electric field. Compared to chloride and bromide, iodide is directly observed with a net negatively charged surface electric field at all salt concentrations measured (0.2 to 3.0 mol/kg water). Also, above the 2 M region, bromide is observed with a net negatively charged surface. Although several scenarios contribute to this effect, it is most likely due to the surface enrichment of bromide and iodide. While the results of this study are pertinent to determining the specific interfacial reactivity of aqueous halides, these anions seldom transpire as single-halide systems in the natural environment. Therefore, we also provide an outlook on future research concerning surface potential methods and more complex aqueous electrolyte systems.
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Affiliation(s)
- Tehseen Adel
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Ka Chon Ng
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Maria G Vazquez de Vasquez
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Juan Velez-Alvarez
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Heather C Allen
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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5
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Zhao X, Nathanson GM, Andersson GG. Experimental Depth Profiles of Surfactants, Ions, and Solvent at the Angstrom Scale: Studies of Cationic and Anionic Surfactants and Their Salting Out. J Phys Chem B 2020; 124:2218-2229. [PMID: 32075369 DOI: 10.1021/acs.jpcb.9b11686] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neutral impact ion scattering spectroscopy (NICISS) is used to measure the depth profiles of ionic surfactants, counterions, and solvent molecules on the angstrom scale. The chosen surfactants are 0.010 m tetrahexylammonium bromide (THA+/Br-) and 0.0050 m sodium dodecyl sulfate (Na+/DS-) in the absence and presence of 0.30 m NaBr in liquid glycerol. NICISS determines the depth profiles of the elements C, O, Na, S, and Br through the loss in energy of 5 keV He atoms that travel into and out of the liquid, which is then converted into depth. In the absence of NaBr, we find that THA+ and its Br- counterion segregate together because of charge attraction, forming a narrow double layer that is 10 Å wide and 150 times more concentrated than in the bulk. With the addition of NaBr, THA+ is "salted out" to the surface, increasing the interfacial Br- concentration by 3-fold and spreading the anions over a ∼30 Å depth. Added NaBr similarly increases the interfacial concentration of DS- ions and broadens their positions. Conversely, the dissolved Br- ions are significantly depleted over a depth of 0-40 Å from the surface because of charge repulsion from DS- ions within the interfacial region. These different interfacial Br- propensities correlate with previously measured gas-liquid reactivities: gaseous Cl2 readily reacts with Br- ions in the presence of THA+ but drops 70-fold in the presence of DS-, demonstrating that surfactant headgroup charge controls the reactivity of Br- through changes in its depth profile.
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Affiliation(s)
- Xianyuan Zhao
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Gilbert M Nathanson
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Gunther G Andersson
- Institute for Nanoscale Science and Technology, Flinders University, Adelaide, SA 5001, Australia
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Lin L, Husek J, Biswas S, Baumler SM, Adel T, Ng KC, Baker LR, Allen HC. Iron(III) Speciation Observed at Aqueous and Glycerol Surfaces: Vibrational Sum Frequency and X-ray. J Am Chem Soc 2019; 141:13525-13535. [PMID: 31345028 DOI: 10.1021/jacs.9b05231] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lu Lin
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Jakub Husek
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Somnath Biswas
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Stephen M. Baumler
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Tehseen Adel
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Ka Chon Ng
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - L. Robert Baker
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Heather C. Allen
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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7
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Ben Jabrallah S, Malloggi F, Belloni L, Girard L, Novikov D, Mocuta C, Thiaudière D, Daillant J. Electrolytes at interfaces: accessing the first nanometers using X-ray standing waves. Phys Chem Chem Phys 2016; 19:167-174. [PMID: 27929155 DOI: 10.1039/c6cp06888j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ion-surface interactions are of high practical importance in a wide range of technological, environmental and biological problems. In particular, they ultimately control the electric double layer structure, hence the interaction between particles in aqueous solutions. Despite numerous achievements, progress in their understanding is still limited by the lack of experimental determination of the surface composition with appropriate resolution. Tackling this challenge, we have developed a method based on X-ray standing waves coupled to nano-confinement which allows the determination of ion concentrations at a solid-solution interface with a sub-nm resolution. We have investigated mixtures of KCl/CsCl and KCl/KI in 0.1 mM to 10 mM concentrations on silica surfaces and obtained quantitative information on the partition of ions between bulk and Stern layer as well as their distribution in the Stern layer. Regarding partition of potassium ions, our results are in agreement with a recent AFM study. We show that in a mixture of KCl and KI, chloride ions exhibit a higher surface propensity than iodide ions, having a higher concentration within the Stern layer and being on average closer to the surface by ≈1-2 Å, in contrast to the solution water interface. Confronting such data with molecular simulations will lead to a precise understanding of ionic distributions at aqueous interfaces.
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Affiliation(s)
- Soumaya Ben Jabrallah
- Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif sur Yvette Cedex, France.
| | - Florent Malloggi
- Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif sur Yvette Cedex, France.
| | - Luc Belloni
- Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif sur Yvette Cedex, France.
| | - Luc Girard
- ICSM UMR 5257 - CEA/CNRS/UM/ENSCM, Site de Marcoule, Bâtiment 426 BP 17171 F-30207 Bagnols sur Cèze Cedex, France
| | - Dmitri Novikov
- Deutsches Elektronensynchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Cristian Mocuta
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Dominique Thiaudière
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Jean Daillant
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
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8
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Peshkova TV, Minkov IL, Tsekov R, Slavchov RI. Adsorption of Ions at Uncharged Insoluble Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8858-8871. [PMID: 27529571 DOI: 10.1021/acs.langmuir.6b02349] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A method is proposed for the experimental determination of the adsorption of inorganic electrolytes at a surface covered with insoluble surfactant monolayer. This task is complicated by the fact that the change of the salt concentration alters both chemical potentials of the electrolyte and the surfactant. Our method resolves the question by combining data for the surface pressure versus area of the monolayer at several salt concentrations with data for the equilibrium spreading pressure of crystals of the surfactant (used to fix a standard state). We applied the method to alcohols spread at the surface of concentrated halide solutions. The measured salt adsorption is positive and has nonmonotonic dependence on the area per surfactant molecule. For the liquid expanded film, depending on the concentration, there is one couple of ions adsorbed per each 3-30 surfactant molecules. We analyzed which ion, the positive or the negative, stands closer to the surface, by measuring the effect of NaCl on the Volta potential of the monolayer. The potentiometric data suggest that Na(+) is specifically adsorbed, while Cl(-) remains in the diffuse layer, i.e., the surface is positively charged. The observed reverse Hofmeister series of the adsorptions of NaF, NaCl, and NaBr suggests the same conclusion holds for all these salts. The force that causes the adsorption of Na(+) seems to be the interaction of the ion with the dipole moment of the monolayer.
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Affiliation(s)
- Tatyana V Peshkova
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
| | - Ivan L Minkov
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
- Department of Chemistry, Biochemistry, Physiology, and Pathophysiology, Faculty of Medicine, Sofia University , 1 Koziak Street, 1407 Sofia, Bulgaria
| | - Roumen Tsekov
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
| | - Radomir I Slavchov
- Department of Physical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University , 1 J. Bourchier Boulevard, 1164 Sofia, Bulgaria
- Department of Chemical Engineering and Biotechnology, Cambridge University , Pembroke Street, New Museums Site, CB2 3RA Cambridge, United Kingdom
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9
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Bera MK, Antonio MR. Aggregation of Heteropolyanions Implicates the Presence of Zundel Ions Near Air-Water Interfaces. ChemistrySelect 2016. [DOI: 10.1002/slct.201600441] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mrinal K. Bera
- Chemical Sciences and Engineering Division; Argonne National Laboratory; Argonne Illinois 60439 United States
- DUBBLE-CRG; ESRF-The European Synchrotron Radiation Facility CS40220; 38043 Grenoble Cedex 9 France
| | - Mark R. Antonio
- Chemical Sciences and Engineering Division; Argonne National Laboratory; Argonne Illinois 60439 United States
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10
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Li J, Wang F. Pairwise-additive force fields for selected aqueous monovalent ions from adaptive force matching. J Chem Phys 2016; 143:194505. [PMID: 26590540 DOI: 10.1063/1.4935599] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Simple non-polarizable potentials were developed for Na(+), K(+), Cl(-), and Br(-) using the adaptive force matching (AFM) method with ab initio MP2 method as reference. Our MP2-AFM force field predicts the solvation free energies of the four salts formed by the ions with an error of no more than 5%. Other properties such as the ion-water radial distribution functions, first solvation shell water tilt angle distributions, ion diffusion constants, concentration dependent diffusion constant of water, and concentration dependent surface tension of the solutions were calculated with this potential. Very good agreement was achieved for these properties. In particular, the diffusion constants of the ions are within 6% of experimental measurements. The model predicts bromide to be enriched at the interface in the 1.6M KBr solution but predicts the ion to be repelled for the surface at lower concentration.
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Affiliation(s)
- Jicun Li
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Feng Wang
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
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11
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Hua W, Verreault D, Huang Z, Adams EM, Allen HC. Cation Effects on Interfacial Water Organization of Aqueous Chloride Solutions. I. Monovalent Cations: Li+, Na+, K+, and NH4+. J Phys Chem B 2014; 118:8433-40. [PMID: 24798506 DOI: 10.1021/jp503132m] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wei Hua
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Dominique Verreault
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Zishuai Huang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Ellen M. Adams
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Heather C. Allen
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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12
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13
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Shapovalov VL, Möhwald H, Konovalov OV, Knecht V. Negligible water surface charge determined using Kelvin probe and total reflection X-ray fluorescence techniques. Phys Chem Chem Phys 2013; 15:13991-8. [PMID: 23842782 DOI: 10.1039/c3cp51575c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The water surface charge has been extensively debated in recent decades. Electrophoretic mobilities of air bubbles in water and disjoining pressures between the surfaces of aqueous films suggest that the surface of water exhibits a significant negative charge. This is commonly attributed to a strong adsorption of hydroxide ions at the interface, though spectroscopic measurements and simulation studies suggest surface depletion of hydroxide ions. Alternatively, the negative surface charge could arise from surface contamination with trace charged surfactants. We have probed the variation in the surface charge of water with pH by measuring surface potentials using the Kelvin probe technique. Independently, the abundance in the interfacial layer of "reporter ions" (Rb(+) and Br(-)), which must be affected by a charged surface, has been monitored using the total reflection X-ray fluorescence (TRXF) technique. Special care was taken to prove the high sensitivity of this technique as well as to avoid surface contaminants. The magnitude of the surface charge was found to be below 1 e per 500 nm(2) (TRXF). No evidence of variations in the surface potential between pH 2-3 and pH 9-12 was detected within the accuracies of the methods (5 mV for Kelvin probe and 2 mV for TRXF). Hence, our findings suggest that the clean water surface exhibits negligible charge in a wide pH range.
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14
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Dang LX, Sun X, Ginovska-Pangovska B, Annapureddy HVR, Truong TB. Understanding ion-ion interactions in bulk and aqueous interfaces using molecular simulations. Faraday Discuss 2013; 160:151-60; discussion 207-24. [PMID: 23795498 DOI: 10.1039/c2fd20093g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In addition to its scientific significance, the distribution of ions in the bulk and at aqueous interfaces is also very important for practical reasons. Providing a quantitative description of the ionic distribution, and describing interactions between ions in different environments, remains a challenge, and is the subject of current debate. In this study, we found that interionic potentials of mean force (PMFs) and interfacial properties are very sensitive to the ion-ion interaction potential models. Our study predicted a Sr(2+)--CI- PMF with no contact ion-pair state and a shallow solvent-separated ion-pair state. In addition, we were able to quantitatively capture the experimental X-ray reflectivity results of the aqueous salt interface of the Sr(2+)--Cl- ion-pair, and provided a detailed physical description of the interfacial structure for this system. We also predicted the Xray reflectivity results for SrBr2 and SrI2 systems.
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Affiliation(s)
- Liem X Dang
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, WA4 93352, USA.
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15
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Surface tension and surface Δχ-potential of concentrated Z+:Z- electrolyte solutions. J Colloid Interface Sci 2013; 403:113-26. [PMID: 23684224 DOI: 10.1016/j.jcis.2013.04.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/10/2013] [Accepted: 04/12/2013] [Indexed: 11/23/2022]
Abstract
Schmutzer's model for the surface of aqueous electrolyte solutions is generalized to Z+:Z- salts. The thickness of the ion-free layer is calculated from the thickness of the "hydrophobic gap" at the water surface (1.38Å) and the radii of the ionic hydration shells. The overlap between the adsorption and the diffuse double layers is accounted for. The proposed model predicts the dependence of the surface tension σ and the surface Δχ-potential on the electrolyte concentration c(el) in agreement with the available data, without adjustable parameters. The Hofmeister effect on σ for salts of the same valence type is explained with their ion-specific activity coefficients. The negative value (toward air) of the Δχ-potential of most 1:1 electrolytes originates from the dipole moment of the water molecules at the surface. The negative χ-potential due to water dipoles is inversely proportional to the dielectric permittivity ε of the solution. Since ε diminishes as c(el) increases, most 1:1 electrolyte solutions exhibit a more negative χ-potential than pure water (Δχ<0). The Hofmeister series of Δχ of 1:1 salts (Δχ(LiCl) ≈ Δχ(NaCl)<Δχ(KCl)<Δχ(KF)) follows the corresponding series of ε (ε(LiCl) ≈ ε(NaCl)<ε(KCl)<ε(KF)). The theory allows the estimation of the surface potential χ0 of pure water from the experimental data for electrolyte solutions; the result, χ0 ≈ -100 mV, confirms the value currently accepted in the literature.
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16
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Hou B, Laanait N, Yu H, Bu W, Yoon J, Lin B, Meron M, Luo G, Vanysek P, Schlossman ML. Ion Distributions at the Water/1,2-Dichloroethane Interface: Potential of Mean Force Approach to Analyzing X-ray Reflectivity and Interfacial Tension Measurements. J Phys Chem B 2013; 117:5365-78. [DOI: 10.1021/jp401892y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Binyang Hou
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Nouamane Laanait
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Hao Yu
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Wei Bu
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Jaesung Yoon
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Binhua Lin
- The
Center for Advanced Radiation
Sources, University of Chicago, Chicago,
Illinois 60637, United States
| | - Mati Meron
- The
Center for Advanced Radiation
Sources, University of Chicago, Chicago,
Illinois 60637, United States
| | - Guangming Luo
- BSRF, Institute of High Energy
Physics, Chinese Academy of Sciences, Beijing,
100049, China
| | - Petr Vanysek
- Department of Chemistry & Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States
| | - Mark L. Schlossman
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
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17
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Tobias DJ, Stern AC, Baer MD, Levin Y, Mundy CJ. Simulation and Theory of Ions at Atmospherically Relevant Aqueous Liquid-Air Interfaces. Annu Rev Phys Chem 2013; 64:339-59. [DOI: 10.1146/annurev-physchem-040412-110049] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Douglas J. Tobias
- Department of Chemistry, University of California, Irvine, California 92697-2025; ,
| | - Abraham C. Stern
- Department of Chemistry, University of California, Irvine, California 92697-2025; ,
| | - Marcel D. Baer
- Chemical and Materials Science Division, Pacific Northwest National Laboratory, Richland, Washington 99352; ,
| | - Yan Levin
- Insituto de Física, Universidade Federal do Rio Grande do Sul, CEP 91501-970 Porto Alegre, RS, Brazil;
| | - Christopher J. Mundy
- Chemical and Materials Science Division, Pacific Northwest National Laboratory, Richland, Washington 99352; ,
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18
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Cummings OT, Wick CD. Computational study on the effect of alkyl chain length on alkane–water interfacial width. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2012.11.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Guerrero-García GI, Olvera de la Cruz M. Inversion of the Electric Field at the Electrified Liquid–Liquid Interface. J Chem Theory Comput 2012; 9:1-7. [DOI: 10.1021/ct300673m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
| | - Mónica Olvera de la Cruz
- Department of Materials
Science,
Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemical Engineering,
Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern
University, Evanston, Illinois 60208, United States
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20
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Yagasaki T, Saito S, Ohmine I. Effects of nonadditive interactions on ion solvation at the water/vapor interface: a molecular dynamics study. J Phys Chem A 2010; 114:12573-84. [PMID: 21077653 DOI: 10.1021/jp1084795] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The solvation of halide ions at the water/vapor interface is investigated by using molecular dynamics simulations with nonpolarizable molecular mechanical (MM), polarizable MM, and quantum mechanical (QM)/MM methods. The free energy profile of the ion solvation is decomposed into the energy and the entropic contributions along the ion displacement from inside to the surface of water. It is found that the surface affinity of the ion, relative to the bulk value, is determined by a subtle balance between the energetic destabilization and the entropic stabilization with the ion displacement. The amount of energetic destabilization is found to be reduced when nonadditive interactions are included, as in the polarizable MM and QM/MM models. The structure of water around the ion at the interface is also largely modified when the higher order effects are considered. For example, the induced dipole effect enhances the solvation structure around the ion at the interface significantly and thus reduces the amount of entropic stabilization at the interface, relative to in the bulk. It is found that this induced dipole effect causes the slowing in the ion-water hydrogen bond dynamics at the interface. On the other hand, the higher order induced multipole effects in the QM/MM method suppress both the excessive enhancement of the solvation structure and the slowing of the ion-water hydrogen bond dynamics at the interface. The present study demonstrates that not only the induced dipole moment but also the higher order induced multipole moments, which are neglected in standard empirical models, are essential for the correct description of the ion solvation at the water/vapor interface.
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Affiliation(s)
- Takuma Yagasaki
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, and The Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan
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21
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Daillant J. Recent developments and applications of grazing incidence scattering. Curr Opin Colloid Interface Sci 2009. [DOI: 10.1016/j.cocis.2009.04.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Sun X, Wick CD, Dang LX. Computational Studies of Aqueous Interfaces of SrCl2 Salt Solutions. J Phys Chem B 2009; 113:13993-7. [DOI: 10.1021/jp9079525] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiuquan Sun
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, and Chemistry Department, Louisiana Tech University, Ruston, Louisiana 71270
| | - Collin D. Wick
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, and Chemistry Department, Louisiana Tech University, Ruston, Louisiana 71270
| | - Liem X. Dang
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, and Chemistry Department, Louisiana Tech University, Ruston, Louisiana 71270
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23
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Bian HT, Feng RR, Guo Y, Wang HF. Specific Na+ and K+ cation effects on the interfacial water molecules at the air/aqueous salt solution interfaces probed with nonresonant second harmonic generation. J Chem Phys 2009; 130:134709. [DOI: 10.1063/1.3104609] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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24
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Feng RR, Bian HT, Guo Y, Wang HF. Spectroscopic evidence for the specific Na+ and K+ interactions with the hydrogen-bonded water molecules at the electrolyte aqueous solution surfaces. J Chem Phys 2009; 130:134710. [DOI: 10.1063/1.3104610] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Sun X, Dang LX. Computational studies of aqueous interfaces of RbBr salt solutions. J Chem Phys 2009; 130:124709. [DOI: 10.1063/1.3096916] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Abstract
Using synchrotron x-ray reflectivity, I studied the ion-size effect for alkali ions (Na(+), K(+), Rb(+), and Cs(+)), with densities as high as 4x10(18)-7x10(18) m(-2), suspended above the surface of a colloidal solution of silica nanoparticles in the field generated by the surface electric-double layer. I found that large alkali ions preferentially accumulate and replace smaller ones at the surface of the hydrosol, a result qualitatively agreeing with the dependence of the Kharkats-Ulstrup single-ion electrostatic free energy on the ion's radius.
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Affiliation(s)
- Aleksey M Tikhonov
- P. L. Kapitza Institute for Physical Problems, RAS, Kosygina 2, Moscow 119334, Russia.
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27
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Affiliation(s)
- Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Complex Molecular Systems and Biomolecules, 16610 Prague 6, Czech Republic;
| | - Bernd Winter
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany;
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28
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Bian HT, Feng RR, Xu YY, Guo Y, Wang HF. Increased interfacial thickness of the NaF, NaCl and NaBr salt aqueous solutions probed with non-resonant surface second harmonic generation (SHG). Phys Chem Chem Phys 2008; 10:4920-31. [DOI: 10.1039/b806362a] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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29
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Clifford D, Donaldson DJ. Direct Experimental Evidence for a Heterogeneous Reaction of Ozone with Bromide at the Air−Aqueous Interface. J Phys Chem A 2007; 111:9809-14. [PMID: 17803288 DOI: 10.1021/jp074315d] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent experimental and theoretical evidence has indicated an enhancement of the heavier halide ions at the air-aqueous interface, relative to their bulk concentrations. This, along with an order of magnitude discrepancy between measured and predicted Br2 production in the reaction of ozone with deliquesced NaBr aerosol, has led to the suggestion that an interface reaction occurs between ozone and bromide. We have used harmine, a beta-carboline alkaloid, as an interface-sensitive fluorescent pH probe in order to measure pH changes associated with the interfacial reaction of ozone and bromide. The rate of pH change depends upon the bulk bromide concentration in a way which is well described by a Langmuir-Hinshelwood kinetic model. In the presence of octanol at the interface, the rate of pH change tracks the octanol adsorption isotherm, as expected if octanol enhances the concentration of ozone at the surface.
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Affiliation(s)
- Daniel Clifford
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6
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30
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Padmanabhan V, Daillant J, Belloni L, Mora S, Alba M, Konovalov O. Specific ion adsorption and short-range interactions at the air aqueous solution interface. PHYSICAL REVIEW LETTERS 2007; 99:086105. [PMID: 17930961 DOI: 10.1103/physrevlett.99.086105] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2007] [Indexed: 05/25/2023]
Abstract
We have investigated the surface composition of alkali-halide aqueous solutions using grazing incidence x-ray fluorescence. Using mixtures of salts as a means to enhance the short-range effects, small differences in concentration over a few angstrom could be resolved, with, for example I- or Br- > Cl-. In order to explain our data, we need to include an effective potential accounting for the short-range (A) solvent mediated couplings, responsible for specific effects together with dispersion forces. This attractive potential (few k{B}T for halides) leads to concentration profiles which are in good agreement with recent numerical simulations.
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Affiliation(s)
- Viswanath Padmanabhan
- Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire, SCM, bât 125, CEA Saclay, F-91191, Gif-sur-Yvette Cedex, France
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