1
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Qamhieh K. Effect of Dielectric Constant on the Zeta Potential of Spherical Electric Double Layers. Molecules 2024; 29:2484. [PMID: 38893363 PMCID: PMC11173410 DOI: 10.3390/molecules29112484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 04/19/2024] [Accepted: 04/23/2024] [Indexed: 06/21/2024] Open
Abstract
Zeta potential refers to the electrokinetic potential present in colloidal systems, exerting significant influence on the diverse properties of nano-drug delivery systems. The impact of the dielectric constant on the zeta potential and charge inversion of highly charged colloidal particles immersed in a variety of solvents spanning from polar, such as water, to nonpolar solvents and in the presence of multivalent salts was investigated through primitive Monte Carlo (MC) model simulations. Zeta potential, ξ, is decreased with the decreasing dielectric constant of the solvent and upon further increase in the salinity and the valency of the salt. At elevated levels of salt, the colloidal particles become overcharged in all solvents. As a result, their apparent charge becomes opposite in sign to the stoichiometric charge. This reversal of charge intensifies until reaching a saturation point with further increase in salinity.
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Affiliation(s)
- Khawla Qamhieh
- Department of Physics, College of Science and Technology, Al-Quds University, Jerusalem 20287, Palestine
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2
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Elisea-Espinoza JJ, González-Tovar E, Guerrero-García GI. Theoretical description of the electrical double layer for a mixture of n ionic species with arbitrary size and charge asymmetries. I. Spherical geometry. J Chem Phys 2023; 158:2895477. [PMID: 37294907 DOI: 10.1063/5.0151140] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 05/08/2023] [Indexed: 06/11/2023] Open
Abstract
In this work, we propose a theoretical finite element description of the ionic profiles of a general mixture of n species of spherical charged particles dissolved in an implicit solvent, with arbitrary size and charge asymmetries, neutralizing a spherical macroion. This approach aims to close the gap between the nano- and the micro-scales in macroion solutions, taking into account the ion correlations and ionic excluded volume effects consistently. When these last two features are neglected, the classical non-linear Poisson-Boltzmann theory for n ionic species-with different ionic closest approach distances to the colloidal surface-is recovered as a limit case. As a proof of concept, we study the electrical double layer of an electroneutral mixture of oppositely charged colloids and small microions, with an asymmetry 1:333 in size and 1:10 in valence, in salt-free and added salt environments. Our theoretical approach displays a good agreement regarding the ionic profiles, the integrated charge, and the mean electrostatic potential obtained from molecular dynamics simulations with explicit-sized microions. Although the non-linear Poisson-Boltzmann colloid-colloid and colloid-microion profiles differ notably from those obtained via molecular dynamics simulations with explicit small-sized ions, the associated mean electrostatic potential agrees well with the corresponding explicit microion simulations.
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Affiliation(s)
| | - Enrique González-Tovar
- Instituto de Física de la Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, Mexico
| | - Guillermo Iván Guerrero-García
- Facultad de Ciencias de la Universidad Autónoma de San Luis Potosí, Av. Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, Mexico
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3
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Holovko M, Vlachy V, Caprio DD. On the contact conditions for the density and charge profiles in the theory of electrical double layer: from planar to spherical and cylindrical geometry. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.121040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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4
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Guerrero-García GI, Bhuiyan LB, Outhwaite CW, González-Tovar E. Charge asymmetric electrolytes around a rigid cylindrical polyelectrolyte: A generalization of the capacitive compactness. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Size and/or charge asymmetry effects in coulombic fluids in the presence of external fields: From simple electrolytes to molten salts. Biophys Chem 2022; 282:106747. [DOI: 10.1016/j.bpc.2021.106747] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 12/27/2022]
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6
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de Souza JP, Pivnic K, Bazant MZ, Urbakh M, Kornyshev AA. Structural Forces in Ionic Liquids: The Role of Ionic Size Asymmetry. J Phys Chem B 2022; 126:1242-1253. [PMID: 35134297 PMCID: PMC9007453 DOI: 10.1021/acs.jpcb.1c09441] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/04/2022] [Indexed: 11/29/2022]
Abstract
Ionic liquids (ILs) are charged fluids composed of anions and cations of different size and shape. The ordering of charge and density in ILs confined between charged interfaces underlies numerous applications of IL electrolytes. Here, we analyze the screening behavior and the resulting structural forces of a representative IL confined between two charge-varied plates. Using both molecular dynamics simulations and a continuum theory, we contrast the screening features of a more-realistic asymmetric system and a less-realistic symmetric one. The ionic size asymmetry plays a nontrivial role in charge screening, affecting both the ionic density profiles and the disjoining pressure distance dependence. Ionic systems with size asymmetry are stronger coupled systems, and this manifests itself both in their response to the electrode polarization and spontaneous structure formation at the interface. Analytical expressions for decay lengths of the disjoining pressure are obtained in agreement with the pressure profiles computed from molecular dynamics simulations.
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Affiliation(s)
- J. Pedro de Souza
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Karina Pivnic
- School
of Chemistry, The Sackler Center for Computational Molecular and Materials
Science, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Martin Z. Bazant
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
- Department
of Mathematics, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - Michael Urbakh
- School
of Chemistry, The Sackler Center for Computational Molecular and Materials
Science, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Alexei A. Kornyshev
- Department
of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ 2AZ, United Kingdom
- Thomas
Young Centre for Theory and Simulation of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom
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7
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Elisea-Espinoza JJ, González-Tovar E, Martínez-González JA, Galván Peña CG, Guerrero-García GI. On the non-dominance of counterions in the 1:z planar electrical double layer of point-ions. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1916633] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
| | - Enrique González-Tovar
- Instituto de Física de la Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | | | - César G. Galván Peña
- Facultad de Ciencias de la Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
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8
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Downing R, Berntson BK, Bossa GV, May S. Differential capacitance of ionic liquids according to lattice-gas mean-field model with nearest-neighbor interactions. J Chem Phys 2018; 149:204703. [PMID: 30501261 DOI: 10.1063/1.5047490] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The Bragg-Williams free energy is used to incorporate nearest-neighbor interactions into the lattice gas model of a solvent-free ionic liquid near a planar electrode. We calculate the differential capacitance from solutions of the mean-field consistency relation, arriving at an explicit expression in the limit of a weakly charged electrode. The two additional material parameters that appear in the theory-the degree of nonideality and the resistance to concentration changes of each ion type-give rise to different regimes that we identify and discuss. As the nonideality parameter, which becomes more positive for stronger nearest-neighbor attraction between like-charged ions, increases and the electrode is weakly charged, the differential capacitance is predicted to transition through a divergence and subsequently adopt negative values just before the ionic liquid becomes structurally unstable. This is associated with the spontaneous charging of an electrode at vanishing potential. The physical origin of the divergence and the negative sign of the differential capacitance is a nonmonotonic relationship between the surface potential and surface charge density, which reflects the formation of layered domains alternatingly enriched in counterions and coions near the electrode. The decay length of this layered domain pattern, which can be many times larger than the ion size, is reminiscent of the recently introduced concept of "underscreening."
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Affiliation(s)
- Rachel Downing
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Bjorn K Berntson
- Department of Mathematics, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Guilherme V Bossa
- Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José do Rio Preto, SP 15054-000, Brazil
| | - Sylvio May
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA
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9
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González-Tovar E, Lozada-Cassou M, Bhuiyan LB, Outhwaite CW. Comparison of zeta potentials and structure for statistical mechanical theories of a model cylindrical double layer. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2017.12.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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10
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11
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Meneses-Juárez E, Hernández-Gayosso M, Orea P, Odriozola G. Molecular dynamics simulations of brine-surfactant lamellas surrounded by nitrogen at different reservoir conditions. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.02.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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12
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Patra CN. Spherical electric double layers containing mixed electrolytes: A case study for multivalent counterions. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.08.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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14
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Jang S, Shin GR, Kim SC. Primitive electrolyte solutions around a charged colloid: density functional approach. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1321156] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Seanea Jang
- Department of Physics, Andong National University, Andong, Korea
| | - Ghi Ryang Shin
- Department of Physics, Andong National University, Andong, Korea
| | - Soon-Chul Kim
- Department of Physics, Andong National University, Andong, Korea
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15
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González-Tovar E, Bhuiyan LB, Outhwaite CW, Lozada-Cassou M. Reversed electrophoretic mobility of a spherical colloid in the Modified Poisson-Boltzmann approach. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2016.10.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Guerrero-García GI, González-Tovar E, Quesada-Pérez M, Martín-Molina A. The non-dominance of counterions in charge-asymmetric electrolytes: non-monotonic precedence of electrostatic screening and local inversion of the electric field by multivalent coions. Phys Chem Chem Phys 2016; 18:21852-64. [PMID: 27435382 DOI: 10.1039/c6cp03483g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The asymptotic convergence of the thermodynamic and structural properties of unequally-sized charge-symmetric ions in strong electric fields was postulated more than thirty years ago by Valleau and Torrie as the dominance of counterions via the non-linear Poisson-Boltzmann theory [Valleau and Torrie, J. Chem. Phys., 1982, 76, 4623]. According to this mean field prescription, the properties of the electrical double layer near a highly charged electrode immersed in a size-asymmetric binary electrolyte converge to those of a size-symmetric electrolyte if the properties of counterions are the same in both instances. On the other hand, some of the present authors have shown that, in fact, counterions do not dominate the electrical properties of a spherical macroion in the presence of unequally-sized ions, symmetric in valence, if ion correlations and ionic excluded volume effects are taken into account consistently. These ingredients are neglected in the classical Poisson-Boltzmann picture. In the present work, we show the occurrence of the non-dominance of counterions in the opposite scenario, that is, when ions are equally-sized but asymmetric in valence. This is performed in the presence of highly charged colloidal surfaces of spherical and planar geometries for different ionic volume fractions. In addition to the phenomenon of non-dominance of counterions, our simulations and theoretical data also exhibit a non-monotonic order or precedence in the mean electrostatic potential, or electrostatic screening, at the Helmholtz plane of a charged colloid. This interesting behaviour is analyzed as a function of the coion's valence, the ionic volume fraction, and the charge and size of the colloidal particle. All these phenomena are explained in terms of the decay of the electric field near the colloidal surface, and by the appearance of a local inversion of both the electric field and the integrated surface charge density of the colloidal particle in the presence of monovalent counterions and multivalent coions.
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Affiliation(s)
- Guillermo Iván Guerrero-García
- CONACYT - Instituto de Física de la Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí, Mexico.
| | - Enrique González-Tovar
- Instituto de Física de la Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí, Mexico
| | - Manuel Quesada-Pérez
- Departamento de Física, Universidad de Jaén, Escuela Politécnica Superior de Linares, 23700 Linares, Jaén, Spain
| | - Alberto Martín-Molina
- Grupo de Física de Fluidos y Biocoloides, Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
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17
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Wang ZY, Ma Z. Examining the Contributions of Image-Charge Forces to Charge Reversal: Discrete Versus Continuum Modeling of Surface Charges. J Chem Theory Comput 2016; 12:2880-8. [DOI: 10.1021/acs.jctc.6b00057] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhi-Yong Wang
- School
of Optoelectronic Information, Chongqing University of Technology, Chongqing 400054, China
| | - Zengwei Ma
- School
of Optoelectronic Information, Chongqing University of Technology, Chongqing 400054, China
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18
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Patra CN. A three-component model on the structure of colloidal solution with size-asymmetric electrolytes. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1143126] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Chandra N. Patra
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai, India; Homi Bhabha National Institute, Mumbai, India
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19
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Adroher-Benítez I, Ahualli S, Martín-Molina A, Quesada-Pérez M, Moncho-Jordá A. Role of Steric Interactions on the Ionic Permeation Inside Charged Microgels: Theory and Simulations. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00356] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Irene Adroher-Benítez
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Silvia Ahualli
- Departamento
de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Alberto Martín-Molina
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Manuel Quesada-Pérez
- Departamento
de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Arturo Moncho-Jordá
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
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20
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Barrios-Contreras EA, González-Tovar E, Guerrero-García GI. The dominance of small ions in the electric double layer of size- and charge-asymmetric electrolytes: a mean-field study on the charge reversal and surface charge amplification. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1018853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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21
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Patra CN. Structure of fully asymmetric mixed electrolytes around a charged nanoparticle: a density functional and simulation investigation. RSC Adv 2015. [DOI: 10.1039/c5ra00643k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A systematic study on the structure of mixed electrolytes with arbitrary size and charge asymmetry around a charged nanoparticle is carried out using density functional theory and Monte Carlo simulation.
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Affiliation(s)
- Chandra N. Patra
- Theoretical Chemistry Section
- Chemistry Group
- Bhabha Atomic Research Centre
- Mumbai 400 085
- India
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22
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Kim EY, Kim SC, Han YS, Seong BS. Structure of a planar electric double layer containing size-asymmetric ions: density functional approach. Mol Phys 2014. [DOI: 10.1080/00268976.2014.985753] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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23
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Patra CN. Structure of spherical electric double layers with fully asymmetric electrolytes: a systematic study by Monte Carlo simulations and density functional theory. J Chem Phys 2014; 141:184702. [PMID: 25399154 DOI: 10.1063/1.4901217] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A systematic investigation of the spherical electric double layers with the electrolytes having size as well as charge asymmetry is carried out using density functional theory and Monte Carlo simulations. The system is considered within the primitive model, where the macroion is a structureless hard spherical colloid, the small ions as charged hard spheres of different size, and the solvent is represented as a dielectric continuum. The present theory approximates the hard sphere part of the one particle correlation function using a weighted density approach whereas a perturbation expansion around the uniform fluid is applied to evaluate the ionic contribution. The theory is in quantitative agreement with Monte Carlo simulation for the density and the mean electrostatic potential profiles over a wide range of electrolyte concentrations, surface charge densities, valence of small ions, and macroion sizes. The theory provides distinctive evidence of charge and size correlations within the electrode-electrolyte interface in spherical geometry.
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Affiliation(s)
- Chandra N Patra
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
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24
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Ahualli S, Fernández MM, Iglesias G, Delgado ÁV, Jiménez ML. Temperature effects on energy production by salinity exchange. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:12378-12385. [PMID: 25230095 DOI: 10.1021/es500634f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In recent years, the capacitance of the interface between charged electrodes and ionic solutions (the electric double layer) has been investigated as a source of clean energy. Charge is placed on the electrodes either by means of ion-exchange membranes or of an external power source. In the latter method, net energy is produced by simple solution exchange in open circuit, due to the associated decrease in the capacitance of the electric double layer. In this work, we consider the change in capacitance associated with temperature variations: the former decreases when temperature is raised, and, hence, a cycle is possible in which some charge is put on the electrode at a certain potential and returned at a higher one. We demonstrate experimentally that it is thus viable to obtain energy from electric double layers if these are successively contacted with water at different temperatures. In addition, we show theoretically and experimentally that temperature and salinity variations can be conveniently combined to maximize the electrode potential increase. The resulting available energy is also estimated.
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Affiliation(s)
- Silvia Ahualli
- Department of Applied Physics, School of Sciences, University of Granada , 18071 Granada, Granada, Spain
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25
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Moncho-Jordá A, Adroher-Benítez I. Ion permeation inside microgel particles induced by specific interactions: from charge inversion to overcharging. SOFT MATTER 2014; 10:5810-5823. [PMID: 24974885 DOI: 10.1039/c4sm00243a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this work we have performed a theoretical study of a system formed by ionic microgels in the presence of monovalent salt with the help of Ornstein-Zernike integral equations within the hypernetted-chain (HNC) approximation. We focus in particular on analysing the role that the short-range specific interactions between the polymer fibres of the microgel and the incoming ions have on the equilibrium ion distribution inside and outside the microgel. For this purpose, a theoretical model based on the equilibrium partitioning effect is developed to determine the interaction between the microgel particle and a single ion. The results indicate that when counterions are specifically attracted to the polymer fibres of the microgel, an enhanced counterion accumulation occurs that induces the charge inversion of the microgel and a strong increase of the microgel net charge (or overcharging). In the case of coions, the specific attraction is also able to provoke the coion adsorption even though they are electrostatically repelled, and so increasing the microgel charge (true overcharging). Moreover, we show that ion adsorption onto the microgel particle is very different in swollen and shrunken states due to the competition between specific attraction and steric repulsion. In particular, ion adsorption occurs preferentially in the internal core of the particle for swollen states, whereas it is mainly concentrated in the external shell for de-swollen configurations. Finally, we observe the existence of a critical salt concentration, where the net charge of the microgels vanishes; above this inversion point the net charge of the microgels increases again, thus leading to reentrant stability of microgel suspensions.
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Affiliation(s)
- A Moncho-Jordá
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain.
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26
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Medasani B, Ovanesyan Z, Thomas DG, Sushko ML, Marucho M. Ionic asymmetry and solvent excluded volume effects on spherical electric double layers: a density functional approach. J Chem Phys 2014; 140:204510. [PMID: 24880304 PMCID: PMC4039739 DOI: 10.1063/1.4876002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 04/29/2014] [Indexed: 02/06/2023] Open
Abstract
In this article, we present a classical density functional theory for electrical double layers of spherical macroions that extends the capabilities of conventional approaches by accounting for electrostatic ion correlations, size asymmetry, and excluded volume effects. The approach is based on a recent approximation introduced by Hansen-Goos and Roth for the hard sphere excess free energy of inhomogeneous fluids [J. Chem. Phys. 124, 154506 (2006); Hansen-Goos and Roth, J. Phys.: Condens. Matter 18, 8413 (2006)]. It accounts for the proper and efficient description of the effects of ionic asymmetry and solvent excluded volume, especially at high ion concentrations and size asymmetry ratios including those observed in experimental studies. Additionally, we utilize a leading functional Taylor expansion approximation of the ion density profiles. In addition, we use the mean spherical approximation for multi-component charged hard sphere fluids to account for the electrostatic ion correlation effects. These approximations are implemented in our theoretical formulation into a suitable decomposition of the excess free energy which plays a key role in capturing the complex interplay between charge correlations and excluded volume effects. We perform Monte Carlo simulations in various scenarios to validate the proposed approach, obtaining a good compromise between accuracy and computational cost. We use the proposed computational approach to study the effects of ion size, ion size asymmetry, and solvent excluded volume on the ion profiles, integrated charge, mean electrostatic potential, and ionic coordination number around spherical macroions in various electrolyte mixtures. Our results show that both solvent hard sphere diameter and density play a dominant role in the distribution of ions around spherical macroions, mainly for experimental water molarity and size values where the counterion distribution is characterized by a tight binding to the macroion, similar to that predicted by the Stern model.
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Affiliation(s)
- Bharat Medasani
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA
| | - Zaven Ovanesyan
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA
| | - Dennis G Thomas
- Pacific Northwest National Laboratory, Richland, Washington 99352-0999, USA
| | - Maria L Sushko
- Pacific Northwest National Laboratory, Richland, Washington 99352-0999, USA
| | - Marcelo Marucho
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249-5003, USA
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27
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Kim EY, Kim SC. Electric double layer for a size-asymmetric electrolyte around a spherical colloid. J Chem Phys 2014. [DOI: 10.1063/1.4871499] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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28
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Kim EY, Kim SC. Ionic density distributions near the charged colloids: spherical electric double layers. J Chem Phys 2013; 139:194711. [PMID: 24320348 DOI: 10.1063/1.4832379] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have studied the structure of the spherical electric double layers on charged colloids by a density functional perturbation theory, which is based both on the modified fundamental-measure theory for the hard spheres and on the one-particle direct correlation functional (DCF) for the electronic residual contribution. The contribution of one-particle DCF has been approximated as the functional integration of the second-order correlation function of the ionic fluids in a bulk phase. The calculated result is in very good agreement with the computer simulations for the ionic density distributions and the zeta potentials over a wide range of macroion sizes and electrolyte concentrations, and compares with the results of Yu et al. [J. Chem. Phys. 120, 7223 (2004)] and modified Poisson-Boltzmann approximation [L. B. Bhuiyan and C. W. Outhwaite, Condens. Matter Phys. 8, 287 (2005)]. The present theory is able to provide interesting insights about the charge inversion phenomena occurring at the interface.
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Affiliation(s)
- Eun-Young Kim
- Department of Physics, Andong National University, Andong 760-749, South Korea
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29
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Manzanilla-Granados HM, Lozada-Cassou M. Modified Colloidal Primitive Model as a Homogeneous Surface Charge Distribution: ζ-Potential. J Phys Chem B 2013; 117:11812-29. [DOI: 10.1021/jp403313k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Héctor M. Manzanilla-Granados
- Escuela
Superior de Computo, Instituto Politécnico Nacional, U. P. Adolfo López
Mateos, Ciudad de México, 07738, México
| | - Marcelo Lozada-Cassou
- Programa
de Ingeniería Molecular, Instituto Mexicano del Petróleo, Col. San
Bartolo Atepehuacan C.P., Ciudad de Mexico, 07730, México
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30
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Moncho-Jordá A. Effective charge of ionic microgel particles in the swollen and collapsed states: The role of the steric microgel-ion repulsion. J Chem Phys 2013; 139:064906. [DOI: 10.1063/1.4817852] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Predictions of the maximum energy extracted from salinity exchange inside porous electrodes. J Colloid Interface Sci 2013; 402:340-9. [DOI: 10.1016/j.jcis.2013.03.068] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 03/22/2013] [Accepted: 03/25/2013] [Indexed: 11/24/2022]
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32
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Moncho-Jordá A, Anta JA, Callejas-Fernández J. Effective electrostatic interactions arising in core-shell charged microgel suspensions with added salt. J Chem Phys 2013; 138:134902. [DOI: 10.1063/1.4798708] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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33
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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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34
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Luchko T, Joung IS, Case DA. Integral Equation Theory of Biomolecules and Electrolytes. INNOVATIONS IN BIOMOLECULAR MODELING AND SIMULATIONS 2012. [DOI: 10.1039/9781849735049-00051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The so-called three-dimensional version (3D-RISM) can be used to describe the interactions of solvent components (here we treat water and ions) with a chemical or biomolecular solute of arbitrary size and shape. Here we give an overview of the current status of such models, describing some aspects of “pure” electrolytes (water plus simple ions) and of ionophores, proteins and nucleic acids in the presence of water and salts. Here we focus primarily on interactions with water and dissolved salts; as a practical matter, the discussion is mostly limited to monovalent ions, since studies of divalent ions present many difficult problems that have not yet been addressed. This is not a comprehensive review, but covers a few recent examples that illustrate current issues.
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Affiliation(s)
- Tyler Luchko
- Department of Chemistry and Chemical Biology and BioMaPS Institute Rutgers University Piscataway NJ 08854, USA
| | - In Suk Joung
- Department of Chemistry and Chemical Biology and BioMaPS Institute Rutgers University Piscataway NJ 08854, USA
| | - David A. Case
- Department of Chemistry and Chemical Biology and BioMaPS Institute Rutgers University Piscataway NJ 08854, USA
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35
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Lue L, Linse P. Macroion solutions in the cell model studied by field theory and Monte Carlo simulations. J Chem Phys 2012; 135:224508. [PMID: 22168704 DOI: 10.1063/1.3665450] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Aqueous solutions of charged spherical macroions with variable dielectric permittivity and their associated counterions are examined within the cell model using a field theory and Monte Carlo simulations. The field theory is based on separation of fields into short- and long-wavelength terms, which are subjected to different statistical-mechanical treatments. The simulations were performed by using a new, accurate, and fast algorithm for numerical evaluation of the electrostatic polarization interaction. The field theory provides counterion distributions outside a macroion in good agreement with the simulation results over the full range from weak to strong electrostatic coupling. A low-dielectric macroion leads to a displacement of the counterions away from the macroion.
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Affiliation(s)
- Leo Lue
- Department of Chemical and Process Engineering, University of Strathclyde James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom.
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36
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Manzanilla-Granados HM, Jiménez-Ángeles F, Lozada-Cassou M. Polarity Inversion of ζ-Potential in Concentrated Colloidal Dispersions. J Phys Chem B 2011; 115:12094-7. [DOI: 10.1021/jp2032324] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
| | - Felipe Jiménez-Ángeles
- Programa de Ingeniera Molecular, Instituto Mexicano del Petróleo, Lázaro Cárdenas 152, 07730 México, D. F., México
| | - Marcelo Lozada-Cassou
- Programa de Ingeniera Molecular, Instituto Mexicano del Petróleo, Lázaro Cárdenas 152, 07730 México, D. F., México
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37
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Modak B, Patra CN, Ghosh SK, Das P. Structure of Colloidal Solution in Presence of Mixed Electrolytes: A Solvent Restricted Primitive Model Study. J Phys Chem B 2011; 115:12126-34. [DOI: 10.1021/jp204913d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Brindaban Modak
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Chandra N. Patra
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Swapan K. Ghosh
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Priyanka Das
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
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38
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Goel T, Patra CN, Ghosh SK, Mukherjee T. Effect of Ionic Size on the Structure of Cylindrical Electric Double Layers: A Systematic Study by Monte Carlo Simulations and Density Functional Theory. J Phys Chem B 2011; 115:10903-10. [DOI: 10.1021/jp203779t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Teena Goel
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Chandra N. Patra
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Swapan K. Ghosh
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Tulsi Mukherjee
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India
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39
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Guerrero-García GI, González-Tovar E, Olvera de la Cruz M. Entropic effects in the electric double layer of model colloids with size-asymmetric monovalent ions. J Chem Phys 2011; 135:054701. [DOI: 10.1063/1.3622046] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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40
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Vernizzi G, Guerrero-García GI, de la Cruz MO. Coulomb interactions in charged fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:016707. [PMID: 21867343 DOI: 10.1103/physreve.84.016707] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 05/22/2011] [Indexed: 05/31/2023]
Abstract
The use of Ewald summation schemes for calculating long-range Coulomb interactions, originally applied to ionic crystalline solids, is a very common practice in molecular simulations of charged fluids at present. Such a choice imposes an artificial periodicity which is generally absent in the liquid state. In this paper we propose a simple analytical O(N(2)) method which is based on Gauss's law for computing exactly the Coulomb interaction between charged particles in a simulation box, when it is averaged over all possible orientations of a surrounding infinite lattice. This method mitigates the periodicity typical of crystalline systems and it is suitable for numerical studies of ionic liquids, charged molecular fluids, and colloidal systems with Monte Carlo and molecular dynamics simulations.
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Affiliation(s)
- Graziano Vernizzi
- Department of Physics and Astronomy, Siena College, Loudonville, New York 12211, USA.
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41
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Walker DA, Kowalczyk B, de la Cruz MO, Grzybowski BA. Electrostatics at the nanoscale. NANOSCALE 2011; 3:1316-44. [PMID: 21321754 DOI: 10.1039/c0nr00698j] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Electrostatic forces are amongst the most versatile interactions to mediate the assembly of nanostructured materials. Depending on experimental conditions, these forces can be long- or short-ranged, can be either attractive or repulsive, and their directionality can be controlled by the shapes of the charged nano-objects. This Review is intended to serve as a primer for experimentalists curious about the fundamentals of nanoscale electrostatics and for theorists wishing to learn about recent experimental advances in the field. Accordingly, the first portion introduces the theoretical models of electrostatic double layers and derives electrostatic interaction potentials applicable to particles of different sizes and/or shapes and under different experimental conditions. This discussion is followed by the review of the key experimental systems in which electrostatic interactions are operative. Examples include electroactive and "switchable" nanoparticles, mixtures of charged nanoparticles, nanoparticle chains, sheets, coatings, crystals, and crystals-within-crystals. Applications of these and other structures in chemical sensing and amplification are also illustrated.
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Affiliation(s)
- David A Walker
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA
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42
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Modak B, Patra CN, Ghosh SK, Vijayasundar J. Effect of ionic size on the structure of spherical double layers: a Monte Carlo simulation and density functional theory study. Mol Phys 2011. [DOI: 10.1080/00268976.2010.544265] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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43
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The ζ-potential for a concentrated colloidal dispersion: The colloidal primitive model vs. the cell model. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2010.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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44
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Colla TE, Levin Y. The renormalized Jellium model of colloidal suspensions with multivalent counterions. J Chem Phys 2010; 133:234105. [DOI: 10.1063/1.3523349] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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45
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Patra CN. Structure of spherical electric double layers containing mixed electrolytes: a systematic study by Monte Carlo simulations and density functional theory. J Phys Chem B 2010; 114:10550-7. [PMID: 20701385 DOI: 10.1021/jp1042975] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structure of spherical electric double layers in the presence of mixed electrolytes is studied using Monte Carlo simulation and density functional theory within the restricted primitive model. The macroion is modeled as an impenetrable charged hard sphere carrying a uniform surface charge density, surrounded by the small ions represented as charged hard spheres, and the solvent is taken as a dielectric continuum. The density functional theory uses a partially perturbative scheme, where the hard-sphere contribution to the one-particle correlation function is evaluated using weighted density approximation and the ionic interactions are calculated using a second-order functional Taylor expansion with respect to a bulk electrolyte. The Monte Carlo simulations have been performed in canonical ensemble. The system is studied at varying ionic concentrations, at different concentration ratios of mono- and multivalent counterions of mixed electrolytes, at different diameters of hard spheres, at different macroion radius, and at varying polyion surface charge densities. The theoretical predictions in terms of the density profiles and the mean electrostatic potential profiles are found to be in good agreement with the simulation results. This model study shows clear manipulations of ionic size and charge correlations in dictating a number of interesting phenomena relating to width of the diffuse layer and charge inversion under different parametric conditions.
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Affiliation(s)
- Chandra N Patra
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India.
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46
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Jha PK, Sknepnek R, Guerrero-García GI, Olvera de la Cruz M. A Graphics Processing Unit Implementation of Coulomb Interaction in Molecular Dynamics. J Chem Theory Comput 2010; 6:3058-65. [DOI: 10.1021/ct100365c] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Prateek K. Jha
- Department of Chemical and Biological Engineering, Department of Materials Science and Engineering, and Department of Chemistry, Northwestern University, Evanston Illinois 60201
| | - Rastko Sknepnek
- Department of Chemical and Biological Engineering, Department of Materials Science and Engineering, and Department of Chemistry, Northwestern University, Evanston Illinois 60201
| | - Guillermo Iván Guerrero-García
- Department of Chemical and Biological Engineering, Department of Materials Science and Engineering, and Department of Chemistry, Northwestern University, Evanston Illinois 60201
| | - Monica Olvera de la Cruz
- Department of Chemical and Biological Engineering, Department of Materials Science and Engineering, and Department of Chemistry, Northwestern University, Evanston Illinois 60201
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47
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Howard JJ, Perkyns JS, Pettitt BM. The behavior of ions near a charged wall-dependence on ion size, concentration, and surface charge. J Phys Chem B 2010; 114:6074-83. [PMID: 20405885 PMCID: PMC2875143 DOI: 10.1021/jp9108865] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A renormalization of the 3D-RISM-HNC integral equation is used to study the solvent and ion distributions at neutral and negatively charged planar atomistic surfaces. The charge density of the surfaces ranged from 0.0 to 0.4116 C/m(2), and the modeled electrolyte solutions consist of the salts NaCl, KCl, and CsCl at concentrations of 0.1, 0.25, and 1.0 M in SPC/E water. The results are qualitatively compared to the results from other integral equation methods and simulations for similar models. We find that the 3D-IEs predict an electric multilayer screening behavior in the solvent and ion distributions in contrast to the double layer anticipated from Poisson-Boltzmann theory. It is observed that the cation size has a significant effect on the distributions near the surface up to three solvation layers beyond which the behavior is the same among the different cations. The response of the distributions to the charged surface is described as an increase in ion and solvent density near the wall. The higher concentration solutions screen the electrostatic source more strongly at the wall as expected. The importance of ion-solvent and ion-ion correlations near the surface is shown through three-body correlation functions which are obtainable from the 3D-IEs in this study.
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Affiliation(s)
- Jesse J Howard
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA
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48
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Patra CN. Molecular solvent model of spherical electric double layers: a systematic study by Monte Carlo simulations and density functional theory. J Phys Chem B 2010; 113:13980-7. [PMID: 19778069 DOI: 10.1021/jp907790t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structure of spherical electric double layers is studied using Monte Carlo simulation and density functional theory by considering solvent as the third component. In this molecular solvent model (MSM), ions and solvent molecules are considered as charged and neutral hard spheres, respectively, having equal diameter. The macroion is considered as an isolated hard sphere having uniform surface charge density surrounded by the electrolyte and the solvent. The theory is partially perturbative as the hard-sphere contribution to the one particle correlation function is evaluated using suitably averaged weighted density, and the ionic part is obtained through a second-order functional Taylor expansion around the bulk electrolyte. The Monte Carlo simulations have been performed in a canonical ensemble. The system is studied at varying concentrations of electrolytes, and the solvent molecules, at different valences of the electrolyte, at different macroion radii, and at varying surface charge densities. The theory is found to be in good agreement with the simulation results over a wide range of parametric conditions. The excluded volume effects due to the molecular nature of the solvent are shown to have much richer features in diffuse layer phenomena like layering and charge inversion.
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Affiliation(s)
- Chandra N Patra
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085, India.
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49
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Guerrero-García GI, González-Tovar E, Chávez-Páez M, Lozada-Cassou M. Overcharging and charge reversal in the electrical double layer around the point of zero charge. J Chem Phys 2010; 132:054903. [DOI: 10.1063/1.3294555] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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50
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Martín-Molina A, Hidalgo-Álvarez R, Quesada-Pérez M. Additional considerations about the role of ion size in charge reversal. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:424105. [PMID: 21715840 DOI: 10.1088/0953-8984/21/42/424105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The effect of the ion size on the charge reversal process is studied via canonical Monte Carlo simulation. To this end, a primitive model of electrolyte is used to analyze the electric double layer formed by an asymmetric electrolyte in the presence of a charged planar wall. Different values of ion diameters and surface charge densities are used so as to determine the conditions at which the charge reversal first occurs. For each case, the apparent surface charge density is calculated as a function of the distance from the charged wall for the different electrolyte concentrations in order to establish the minimal salt concentration required for the charge reversal. We will refer to this electrolyte concentration as the reversal concentration and will show how it depends on the surface charge density and on the ion size. From the apparent surface charge density profiles, the distance from the wall at which the charge reversal arises as well as its intensity can be also inferred.
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Affiliation(s)
- A Martín-Molina
- Grupo de Física de Fluidos y Biocoloides, Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Granada 18071, Spain
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