1
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Fang B, Habibi P, Moultos OA, Lü T, Ning F, Vlugt TJH. Solubilities and Self-Diffusion Coefficients of Light n-Alkanes in NaCl Solutions at the Temperature Range (278.15-308.15) K and Pressure Range (1-300) bar and Thermodynamics Properties of Their Corresponding Hydrates at (150-290) K and (1-7000) bar. JOURNAL OF CHEMICAL AND ENGINEERING DATA 2024; 69:3330-3346. [PMID: 39411182 PMCID: PMC11472311 DOI: 10.1021/acs.jced.3c00225] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/20/2023] [Indexed: 10/19/2024]
Abstract
Continuous Fractional Component Monte Carlo (CFCMC) and molecular dynamics (MD) simulations are performed to calculate the solubilities and self-diffusion coefficients of four light n-alkanes (methane, ethane, propane, and n-butane) in aqueous NaCl solutions as well as the thermodynamic properties of their corresponding hydrate crystals. Correction factors k ij to the Lorentz-Berthelot combining rules for alkane groups (CH3) and water are optimized (k ij = 1.04) by fitting excess chemical potentials to experimental data at 1 bar and 298.15 K. Using these values of k ij , we calculate the solubilities of the four alkanes in aqueous NaCl solutions with different molalities (0-6) mol/kg at different temperatures (278.15-308.15) K and pressures (1, 100, 200, 300) bar. The diffusion coefficients of the four alkanes in NaCl solutions (0-6) mol/kg are calculated at different temperatures (278.15-308.15) K and 1 bar and corrected for the finite-size effects. The lattice parameters of the corresponding hydrates with different guest molecules are computed using MD simulations at different temperatures (150-290) K and pressures (5-700) MPa. Isothermal compressibilities at 287.15 K and thermal expansion coefficients at 14.5 MPa for the corresponding hydrates are calculated. We present an extensive collection of thermodynamic data related to gas hydrates that contribute to a fundamental understanding of natural gas hydrate science.
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Affiliation(s)
- Bin Fang
- School
of Mathematics and Physics, China University
of Geosciences, Wuhan 430074, China
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, Delft 2628CB, The Netherlands
| | - Parsa Habibi
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, Delft 2628CB, The Netherlands
| | - Othonas A. Moultos
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, Delft 2628CB, The Netherlands
| | - Tao Lü
- School
of Automation, China University of Geosciences, Wuhan 430074, China
- Hubei
Key Laboratory of Advanced Control and Intelligent Automation for
Complex Systems, Wuhan 430074, China
| | - Fulong Ning
- Faculty
of Engineering, China University of Geosciences, Wuhan, Hubei 430074, China
- National
Center for International Research on Deep Earth Drilling and Resource
Development, China University of Geosciences, Wuhan 430074, China
| | - Thijs J. H. Vlugt
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, Delft 2628CB, The Netherlands
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2
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Chen C, Xia J, Bahai H. Effect of the Temperature on Interfacial Properties of CO 2/H 2 Mixtures Contacting with Brine and Hydrophilic Silica by Molecular Dynamics Simulations. ENERGY & FUELS : AN AMERICAN CHEMICAL SOCIETY JOURNAL 2023; 37:18986-18995. [PMID: 38094907 PMCID: PMC10714351 DOI: 10.1021/acs.energyfuels.3c03164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/16/2024]
Abstract
Underground H2 storage (UHS) is a promising technology to achieve large-scale, long-term H2 storage. Using CO2 as a cushion gas to maintain the pressure of the reservoir and withdraw stored H2 in the saline aquifer simultaneously enables the implementation of UHS and underground CO2 storage (UCS). The difference in the molecular properties of CO2 and H2 leads to distinct interfacial behavior when in contact with the brine and rock, thereby affecting the flow patterns and trapping mechanisms of gases in geological formations. Accurate prediction of the interfacial properties of CO2, H2, and the mixtures when interacting with brine and rock is crucial to minimizing the uncertainties in UHS and UCS projects. In this study, molecular dynamics (MD) simulations are performed to predict the interfacial tension, surface excess, bubble evolution, and contact angle of CO2, H2, and the mixtures at 10 MPa and 300-400 K. The MD results show that the interaction of CO2 with H2O and hydrophilic silica is considerably stronger than that of H2. The interfacial tension reduces linearly with the temperature in H2-dominated mixture systems, and the surface adsorption of H2 can diminish in a CO2-dominated system or at high-temperature conditions. The hydrophilic silica is more CO2-wet than H2-wet, and the attached CO2 bubble is more easily disconnected. Ions and the temperature play different roles in the contact angle.
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Affiliation(s)
- Cheng Chen
- Department of Mechanical
and Aerospace Engineering, Brunel University
London, Uxbridge UB8 3PH, United
Kingdom
| | - Jun Xia
- Department of Mechanical
and Aerospace Engineering, Brunel University
London, Uxbridge UB8 3PH, United
Kingdom
| | - Hamid Bahai
- Department of Mechanical
and Aerospace Engineering, Brunel University
London, Uxbridge UB8 3PH, United
Kingdom
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3
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Blazquez S, Abascal JLF, Lagerweij J, Habibi P, Dey P, Vlugt TJH, Moultos OA, Vega C. Computation of Electrical Conductivities of Aqueous Electrolyte Solutions: Two Surfaces, One Property. J Chem Theory Comput 2023; 19:5380-5393. [PMID: 37506381 PMCID: PMC10448725 DOI: 10.1021/acs.jctc.3c00562] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Indexed: 07/30/2023]
Abstract
In this work, we computed electrical conductivities under ambient conditions of aqueous NaCl and KCl solutions by using the Einstein-Helfand equation. Common force fields (charge q = ±1 e) do not reproduce the experimental values of electrical conductivities, viscosities, and diffusion coefficients. Recently, we proposed the idea of using different charges to describe the potential energy surface (PES) and the dipole moment surface (DMS). In this work, we implement this concept. The equilibrium trajectories required to evaluate electrical conductivities (within linear response theory) were obtained by using scaled charges (with the value q = ±0.75 e) to describe the PES. The potential parameters were those of the Madrid-Transport force field, which accurately describe viscosities and diffusion coefficients of these ionic solutions. However, integer charges were used to compute the conductivities (thus describing the DMS). The basic idea is that although the scaled charge describes the ion-water interaction better, the integer charge reflects the value of the charge that is transported due to the electric field. The agreement obtained with experiments is excellent, as for the first time electrical conductivities (and the other transport properties) of NaCl and KCl electrolyte solutions are described with high accuracy for the whole concentration range up to their solubility limit. Finally, we propose an easy way to obtain a rough estimate of the actual electrical conductivity of the potential model under consideration using the approximate Nernst-Einstein equation, which neglects correlations between different ions.
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Affiliation(s)
- Samuel Blazquez
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jose L. F. Abascal
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jelle Lagerweij
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Parsa Habibi
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
- Department
of Materials Science and Engineering, Faculty of Mechanical, Maritime
and Materials Engineering, Delft University
of Technology, Mekelweg
2, 2628CD Delft, The Netherlands
| | - Poulumi Dey
- Department
of Materials Science and Engineering, Faculty of Mechanical, Maritime
and Materials Engineering, Delft University
of Technology, Mekelweg
2, 2628CD Delft, The Netherlands
| | - Thijs J. H. Vlugt
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Othonas A. Moultos
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Carlos Vega
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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4
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Alibakhshi A, Steffen J, Pinilla C, Hartke B. Comparison of Implicit and Explicit Solvent Approaches in Ab Initio Evaluation of Thermochemistry in Solution: Application in Studying Boron Isotope Fractionation in Water. J Phys Chem A 2023; 127:2503-2510. [PMID: 36917555 DOI: 10.1021/acs.jpca.3c00154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Evaluation of thermochemistry in solution plays a key role in numerous fields. For this task, the solvent effects are commonly included in theoretical computations based on either implicit or explicit solvent approaches. In the present study, we evaluate and compare the performance of some of the most widely applied methods based on these two approaches. For studying the solvent effect on thermochemistry with an explicit solvent, we demonstrate that partial normal mode analysis with frozen geometry of solvent molecules for multiple solute-solvent configurations can yield quite accurate and reliable results for a drastically reduced computational cost. As a case study, we consider the evaluation of the equilibrium constant for the boron isotope exchange between boric acid and borate (k3-4) in pure and saline water which is of high geochemical importance. Employing three different rigorous and high-precision theoretical approaches, we provide a reliable estimation of k3-4 which is a value within 1.028 to 1.030 for both pure and saline water which is in excellent agreement with experimental data.
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Affiliation(s)
- Amin Alibakhshi
- Theoretical Chemistry, Institute for Physical Chemistry, Christian-Albrechts-University, Olshausenstr. 40, 24118 Kiel, Germany
- Theoretical Chemistry, Ruhr-Universitaet Bochum, D-44780 Bochum, Germany
| | - Julien Steffen
- Theoretical Chemistry, Institute for Physical Chemistry, Christian-Albrechts-University, Olshausenstr. 40, 24118 Kiel, Germany
| | - Carlos Pinilla
- Departamento de Física y Geociencias, Universidad del Norte, Km 5 via Puerto Colombia, Barranquilla 080020, Colombia
- School of Chemistry, University of Bristol, Cantock's Close Road, BS8 1TS Bristol, U.K
| | - Bernd Hartke
- Theoretical Chemistry, Institute for Physical Chemistry, Christian-Albrechts-University, Olshausenstr. 40, 24118 Kiel, Germany
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5
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Yang Y, Pan H, Li X, Luo W, Bharti B. Applications of two-dimensional ion chromatography for analytes determination in environmental matrix: A review. J Chromatogr A 2023; 1694:463908. [PMID: 36913814 DOI: 10.1016/j.chroma.2023.463908] [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: 11/22/2022] [Revised: 02/22/2023] [Accepted: 03/01/2023] [Indexed: 03/06/2023]
Abstract
Ion chromatography (IC) has grown in usage rapidly since its first introduction in 1975. However, IC is still sometimes unable to separate target analytes from coexisting components well with identical elution time, due to the limited resolution and column capacity, especially in the presence of high-level salt matrix. These limitations hence drive IC to develop two-dimensional IC (2D-IC). In this review, we capture the 2D-IC applications in environmental samples via the perspective of coupling different IC columns, which aim to summarize where these 2D-IC methods fit in. In sequence, we firstly review the principles of 2D-IC and emphasize one-pump column-switching IC (OPCS IC) because it is a simplified 2D-IC that only uses one set of IC system. We then compare typical 2D-IC and OPCS IC performances in terms of application scope, method detection limit, drawbacks, and expectations. Finally, we propose some challenges of current methods and opportunities for future research. For instance, it is challenging to couple anion exchange column and capillary column in OPCS IC due to the incompatibility between flow path dimensions and suppressor; coupling ion exclusion column and mixed-bed column may be promising to simultaneously determine anions and cations in weak acids or salts. The details of this study may help practitioners to better understand and implement 2D-IC methods and meanwhile motivate researchers to fill in the knowledge gap in the future.
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Affiliation(s)
- Yang Yang
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, Harbin Institute of Technology (Shenzhen), 518055, PR. China.
| | - Huimei Pan
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, Harbin Institute of Technology (Shenzhen), 518055, PR. China
| | - Xiao Li
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, Harbin Institute of Technology (Shenzhen), 518055, PR. China
| | - Wang Luo
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, Harbin Institute of Technology (Shenzhen), 518055, PR. China
| | - Bandna Bharti
- State Key Laboratory of Urban Water Resource and Environment, Shenzhen Key Laboratory of Organic Pollution Prevention and Control, Harbin Institute of Technology (Shenzhen), 518055, PR. China; Department of Chemistry, DAV University, Jalandhar, Punjab 144001, India
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6
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Blazquez S, Conde MM, Vega C. Scaled charges for ions: An improvement but not the final word for modeling electrolytes in water. J Chem Phys 2023; 158:054505. [PMID: 36754806 DOI: 10.1063/5.0136498] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
In this work, we discuss the use of scaled charges when developing force fields for NaCl in water. We shall develop force fields for Na+ and Cl- using the following values for the scaled charge (in electron units): ±0.75, ±0.80, ±0.85, and ±0.92 along with the TIP4P/2005 model of water (for which previous force fields were proposed for q = ±0.85 and q = ±1). The properties considered in this work are densities, structural properties, transport properties, surface tension, freezing point depression, and maximum in density. All the developed models were able to describe quite well the experimental values of the densities. Structural properties were well described by models with charges equal to or larger than ±0.85, surface tension by the charge ±0.92, maximum in density by the charge ±0.85, and transport properties by the charge ±0.75. The use of a scaled charge of ±0.75 is able to reproduce with high accuracy the viscosities and diffusion coefficients of NaCl solutions for the first time. We have also considered the case of KCl in water, and the results obtained were fully consistent with those of NaCl. There is no value of the scaled charge able to reproduce all the properties considered in this work. Although certainly scaled charges are not the final word in the development of force fields for electrolytes in water, its use may have some practical advantages. Certain values of the scaled charge could be the best option when the interest is to describe certain experimental properties.
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Affiliation(s)
- S Blazquez
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - M M Conde
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain
| | - C Vega
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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7
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Biriukov D, Wang HW, Rampal N, Tempra C, Kula P, Neuefeind JC, Stack AG, Předota M. The "good," the "bad," and the "hidden" in neutron scattering and molecular dynamics of ionic aqueous solutions. J Chem Phys 2022; 156:194505. [PMID: 35597655 DOI: 10.1063/5.0093643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We characterize a concentrated 7.3 m CaCl2 solution, combining neutron diffraction with chloride isotopic substitution (Cl-NDIS) in null water and molecular dynamics (MD) simulations. We elucidate the solution structure, thermodynamic properties, and extent of ion pairing previously suggested as concentration-dependent and often not observed at lower concentrations. Our Cl-NDIS measurements designate the solvent-shared ion pairing as dominant and the contact ion pairing (CIP) as insignificant even under conditions close to the solubility limit. The MD models parameterized against neutron diffraction with calcium isotopic substitution (Ca-NDIS) overestimate CIP despite successfully reproducing most of the Cl-NDIS signal. This drawback originates from the fact that Ca2+-Cl- interactions were primarily "hidden" in the Ca-NDIS signal due to overlapping with Ca2+-Ow and Ca2+-Hw contributions to the total scattering. Contrary, MD models with moderate CIP and possessing generally good performance at high concentrations fail to reproduce the NDIS measurements accurately. Therefore, the electronic polarization, introduced in most of the recent MD models via scaling ionic charges, resolves some but not all parameterization drawbacks. We conclude that despite improving the quality of MD models "on average," the question "which model is the best" has not been answered but replaced by the question "which model is better for a given research." An overall "good" model can still be inappropriate or, in some instances, "bad" and, unfortunately, produce erroneous results. The accurate interpretation of several NDIS datasets, complemented by MD simulations, can prevent such mistakes and help identify the strengths, weaknesses, and convenient applications for corresponding computational models.
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Affiliation(s)
- Denys Biriukov
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Hsiu-Wen Wang
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Nikhil Rampal
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Carmelo Tempra
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Patrik Kula
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Joerg C Neuefeind
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Andrew G Stack
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Milan Předota
- Department of Physics, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic
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8
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Sedano LF, Blazquez S, Noya EG, Vega C, Troncoso J. Maximum in density of electrolyte solutions: Learning about ion-water interactions and testing the Madrid-2019 force field. J Chem Phys 2022; 156:154502. [PMID: 35459318 DOI: 10.1063/5.0087679] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, we studied the effect of Li+, Na+, K+, Mg2+, and Ca2+ chlorides and sulfates on the temperature of maximum density (TMD) of aqueous solutions at room pressure. Experiments at 1 molal salt concentration were carried out to determine the TMD of these solutions. We also performed molecular dynamics simulations to estimate the TMD at 1 and 2 m with the Madrid-2019 force field, which uses the TIP4P/2005 water model and scaled charges for the ions, finding an excellent agreement between experiment and simulation. All the salts studied in this work shift the TMD of the solution to lower temperatures and flatten the density vs temperature curves (when compared to pure water) with increasing salt concentration. The shift in the TMD depends strongly on the nature of the electrolyte. In order to explore this dependence, we have evaluated the contribution of each ion to the shift in the TMD concluding that Na+, Ca2+, and SO4 2- seem to induce the largest changes among the studied ions. The volume of the system has been analyzed for salts with the same anion and different cations. These curves provide insight into the effect of different ions upon the structure of water. We claim that the TMD of electrolyte solutions entails interesting physics regarding ion-water and water-water interactions and should, therefore, be considered as a test property when developing force fields for electrolytes. This matter has been rather unnoticed for almost a century now and we believe it is time to revisit it.
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Affiliation(s)
- L F Sedano
- Depto. Química Física I (Unidad Asociada de I+D+i al CSIC), Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - S Blazquez
- Depto. Química Física I (Unidad Asociada de I+D+i al CSIC), Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - E G Noya
- Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, CSIC, Calle Serrano 119, 28006 Madrid, Spain
| | - C Vega
- Depto. Química Física I (Unidad Asociada de I+D+i al CSIC), Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J Troncoso
- Departamento de Física Aplicada, Universidad de Vigo, Facultad de Ciencias del Campus de Ourense, E 32004 Ourense, Spain
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9
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Lamas CP, Vega C, Noya EG. Freezing point depression of salt aqueous solutions using the Madrid-2019 model. J Chem Phys 2022; 156:134503. [PMID: 35395902 DOI: 10.1063/5.0085051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Salt aqueous solutions are relevant in many fields, ranging from biological systems to seawater. Thus, the availability of a force-field that is able to reproduce the thermodynamic and dynamic behavior of salt aqueous solutions would be of great interest. Unfortunately, this has been proven challenging, and most of the existing force-fields fail to reproduce much of their behavior. In particular, the diffusion of water or the salt solubility are often not well reproduced by most of the existing force-fields. Recently, the Madrid-2019 model was proposed, and it was shown that this force-field, which uses the TIP4P/2005 model for water and non-integer charges for the ions, provides a good description of a large number of properties, including the solution densities, viscosities, and the diffusion of water. In this work, we assess the performance of this force-field on the evaluation of the freezing point depression. Although the freezing point depression is a colligative property that at low salt concentrations depends solely on properties of pure water, a good model for the electrolytes is needed to accurately predict the freezing point depression at moderate and high salt concentrations. The coexistence line between ice and several salt aqueous solutions (NaCl, KCl, LiCl, MgCl2, and Li2SO4) up to the eutectic point is estimated from direct coexistence molecular dynamics simulations. Our results show that this force-field reproduces fairly well the experimentally measured freezing point depression with respect to pure water freezing for all the salts and at all the compositions considered.
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Affiliation(s)
- Cintia P Lamas
- Departamento de Química-Física I (Unidad de I+D+i Asociada al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Carlos Vega
- Departamento de Química-Física I (Unidad de I+D+i Asociada al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Eva G Noya
- Instituto de Química Física Rocasolano, CSIC, C/ Serrano 119, 28006 Madrid, Spain
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10
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Zhao X, Liu Y, Lin D, Zhu W, Ma N, Xu WW, Zhao W, Sun Y, Zeng XC. Anomalous Phase Behaviors of Monolayer NaCl Aqueous Solutions Induced by Effective Coulombic Interactions within Angstrom-Scale Slits. J Phys Chem Lett 2022; 13:2704-2710. [PMID: 35302778 DOI: 10.1021/acs.jpclett.2c00501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Interests in subnanofluidic devices have called for molecular dynamics (MD) simulation studies of the thermodynamic behavior of monolayer salt solution within angstrom-scale slits. However, it still remains a grand challenge to accurately describe the Coulombic interactions by incorporating the effects of charge transfer and electronic dielectric screening. Herein, by using the electronic continuum model, where the effective ion charges are fine-tuned with a scaling factor of λ, we present simulation evidence that the effective Coulombic interactions among Na+/Cl- ions can strongly affect the behavior of monolayer ionic aqueous solution. Our microsecond-scale MD simulations show that only the counterions with moderate effective charges (0.3 ≤ λ ≤ 0.8) can dissolve in monolayer water, whereas the high effective charges (λ ≥ 0.85) induce ions to assemble into monolayer nanocrystals, and ions with the low effective charges (λ ≤ 0.2) exhibit gas-like nanobubble. These findings could provide deeper insights into the physical chemistry behind subnanofluidic iontronic devices.
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Affiliation(s)
- Xiaorong Zhao
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Yuying Liu
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Dongdong Lin
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Weiduo Zhu
- Department of Physics, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Nan Ma
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Wen Wu Xu
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Wenhui Zhao
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Yunxiang Sun
- Department of Physics, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska─Lincoln, Lincoln, Nebraska 68588, United States
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11
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Blazquez S, Conde MM, Abascal JLF, Vega C. The Madrid-2019 force field for electrolytes in water using TIP4P/2005 and scaled charges: Extension to the ions F−, Br−, I−, Rb+, and Cs+. J Chem Phys 2022; 156:044505. [DOI: 10.1063/5.0077716] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- S. Blazquez
- Departamento Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - M. M. Conde
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain
| | - J. L. F. Abascal
- Departamento Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C. Vega
- Departamento Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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12
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Neumann J, Schwierz N. Artificial Intelligence Resolves Kinetic Pathways of Magnesium Binding to RNA. J Chem Theory Comput 2022; 18:1202-1212. [PMID: 35084846 PMCID: PMC8830046 DOI: 10.1021/acs.jctc.1c00752] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Magnesium is an indispensable cofactor in countless vital processes. In order to understand its functional role, the characterization of the binding pathways to biomolecules such as RNA is crucial. Despite the importance, a molecular description is still lacking since the transition from the water-mediated outer-sphere to the direct inner-sphere coordination is on the millisecond time scale and therefore out of reach for conventional simulation techniques. To fill this gap, we use transition path sampling to resolve the binding pathways and to elucidate the role of the solvent in the binding process. The results reveal that the molecular void provoked by the leaving phosphate oxygen of the RNA is immediately filled by an entering water molecule. In addition, water molecules from the first and second hydration shell couple to the concerted exchange. To capture the intimate solute-solvent coupling, we perform a committor analysis as the basis for a machine learning algorithm that derives the optimal deep learning model from thousands of scanned architectures using hyperparameter tuning. The results reveal that the properly optimized deep network architecture recognizes the important solvent structures, extracts the relevant information, and predicts the commitment probability with high accuracy. Our results provide detailed insights into the solute-solvent coupling which is ubiquitous for kosmotropic ions and governs a large variety of biochemical reactions in aqueous solutions.
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Affiliation(s)
- Jan Neumann
- Allianz Global Investors GmbH, Bockenheimer Landstrasse 42, 60323 Frankfurt am Main, Germany
| | - Nadine Schwierz
- Department of Theoretical Biophysics, Max-Planck-Institute of Biophysics, 60438 Frankfurt am Main, Germany
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Falkner S, Schwierz N. Kinetic pathways of water exchange in the first hydration shell of magnesium: Influence of water model and ionic force field. J Chem Phys 2021; 155:084503. [PMID: 34470357 DOI: 10.1063/5.0060896] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Water exchange between the first and second hydration shell is essential for the role of Mg2+ in biochemical processes. In order to provide microscopic insights into the exchange mechanism, we resolve the exchange pathways by all-atom molecular dynamics simulations and transition path sampling. Since the exchange kinetics relies on the choice of the water model and the ionic force field, we systematically investigate the influence of seven different polarizable and non-polarizable water and three different Mg2+ models. In all cases, water exchange can occur either via an indirect or direct mechanism (exchanging molecules occupy different/same position on the water octahedron). In addition, the results reveal a crossover from an interchange dissociative (Id) to an associative (Ia) reaction mechanism dependent on the range of the Mg2+-water interaction potential of the respective force field. Standard non-polarizable force fields follow the Id mechanism in agreement with experimental results. By contrast, polarizable and long-ranged non-polarizable force fields follow the Ia mechanism. Our results provide a comprehensive view on the influence of the water model and the ionic force field on the exchange dynamics and the foundation to assess the choice of the force field in biomolecular simulations.
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Affiliation(s)
| | - Nadine Schwierz
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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Kimani EM, Kemperman AJB, van der Meer WGJ, Biesheuvel PM. Multicomponent mass transport modeling of water desalination by reverse osmosis including ion pair formation. J Chem Phys 2021; 154:124501. [PMID: 33810649 DOI: 10.1063/5.0039128] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Reverse Osmosis (RO) is one of the main membrane technologies currently used for the desalination of seawater and brackish water to produce freshwater. However, the mechanism of transport and separation of ions in RO membranes is not yet fully understood. Besides acid-base reactions (i.e., including the H+-ion), at high concentrations, the salt ions can associate and form ion pairs. In this study, we investigate how to include the formation of these ion pairs in the extended Donnan steric partitioning pore model. We study the desalination of a water source where three ion pairs can be formed (NaCl, MgCl+, and MgCl2) and also include water self-dissociation and the carbonate system. The model assumes infinitely fast reactions, which means that the participating ions are locally at chemical equilibrium with one another. A square stoichiometric reaction matrix composed of active species, moieties, and reactions is formulated. As the final constraint equation, we use the charge balance. The model predicts profiles in concentration, flux, and reaction rates across the membrane for all species and calculates the retention per group of ions. Ion pair formation has an influence on the fluxes of individual ions and therefore influences the retention of ions.
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Affiliation(s)
- E M Kimani
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - A J B Kemperman
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - W G J van der Meer
- Membrane Science and Technology Cluster, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - P M Biesheuvel
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
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