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Mandal SS, Singh SK, Khan S. Role of site-site interaction on the phase equilibria of multiple-site associating fluids in a functionalized slit pore. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:475402. [PMID: 37549673 DOI: 10.1088/1361-648x/acede1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 08/07/2023] [Indexed: 08/09/2023]
Abstract
Vapor-liquid phase equilibria for multiple sites associating fluids with different associating strengths are investigated in a slit pore using grand-canonical transition matrix Monte Carlo method. The increase of critical temperature from two-site to four-site associating fluids at constant site strength is quite significant as compared to that of the one-site to two-site associating fluids, which is more pronounced at higher associating strength (ϵ* = 6). Monomer fraction and cluster size distribution are used to investigate the association of fluid particles in coexistence phases. The monomer fraction for both phases decreases with increased associating sites on the fluid particles due to more site-site interaction with neighboring fluid particles and forming a larger cluster. Therefore, the number of associating sites and their distribution play a vital role in the association of fluid particles. Moreover, the saturation chemical potential changes with the arrangement of the sites. For two-site associating fluids, we observe early vapor-liquid transition when the sites are oppositely placed, and when the sites are placed at 90°, the vapor-liquid transition is observed at the higher chemical potential. Moreover, four-site associating fluids with a square arrangement show early vapor-liquid phase transition, mainly because these arrangements of sites effectively interact with surface sites and the molecules in the next layer.
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Affiliation(s)
- Sashanka Sekhar Mandal
- Department of Chemical & Biochemical Engineering, Indian Institute of Technology Patna, Patna 801103, India
| | - Sudhir Kumar Singh
- Department of Chemical Engineering, Thapar Institute of Engineering and Technology, Patiala 147004, India
| | - Sandip Khan
- Department of Chemical & Biochemical Engineering, Indian Institute of Technology Patna, Patna 801103, India
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Sauer E, Gross J. Prediction of Adsorption Isotherms and Selectivities: Comparison between Classical Density Functional Theory Based on the Perturbed-Chain Statistical Associating Fluid Theory Equation of State and Ideal Adsorbed Solution Theory. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11690-11701. [PMID: 31403314 DOI: 10.1021/acs.langmuir.9b02378] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This study gives an assessment of the predictive capability of classical density functional theory (DFT) for adsorption processes of pure substances and mixtures of spherical and nonspherical molecular species. A Helmholtz energy functional based on the perturbed-chain statistical associating fluid theory (PC-SAFT) is applied to calculate isotherms and selectivities of multicomponent adsorption. In order to unambiguously assess the accuracy of the DFT model, we conduct molecular simulations. Monte Carlo (MC) simulations are performed in the grand canonical ensemble using the transition matrix. Two types of systems are studied: a model system, where fluid-fluid and solid-fluid interactions are defined as (single-site) Lennard-Jones interactions, and a more realistic methane-n-butane mixture in a graphite-like pore. Differences between a slit-shaped and a cylindrical pore geometry are examined for the model system. Adsorption isotherms and selectivities obtained from DFT calculations and MC simulations are found in very good agreement, particularly at high pressures. Capillary condensation observed along adsorption isotherms containing n-butane was accurately predicted, both, in equilibrium pressure and in density-increase. Comparisons with results from the ideal adsorbed solution theory are presented, confirming powerful predictions of the DFT approach.
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Affiliation(s)
- Elmar Sauer
- Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , 70569 Stuttgart , Germany
| | - Joachim Gross
- Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , 70569 Stuttgart , Germany
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Jagiello J, Jaroniec M. 2D-NLDFT adsorption models for porous oxides with corrugated cylindrical pores. J Colloid Interface Sci 2018; 532:588-597. [PMID: 30114648 DOI: 10.1016/j.jcis.2018.08.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 08/06/2018] [Accepted: 08/07/2018] [Indexed: 11/26/2022]
Abstract
In this work, we develop two-dimensional models based on the non-local density functional theory (2D-NLDFT) for the analysis of pore size distribution (PSD) of oxide materials with cylindrical pores with rough and heterogeneous walls. The existing standard NLDFT models for porous oxides assume the smooth energetically uniform surface of the pore walls. Due to this assumption, the calculated theoretical isotherms show typical layering transitions, which are not consistent with the experimental adsorption isotherms measured on real oxide materials. As a result, the fits of standard NLDFT models to N2 or Ar adsorption isotherms show deviations from the experimental points in association with artifacts observed on the calculated PSD plots. The 2D-NLDFT framework allows us to improve the standard model by introducing the corrugation and energetic heterogeneity to the surface of cylindrical pores. The surface roughness and energetic heterogeneity are known characteristics of the oxide surfaces. With these assumptions we develop a comprehensive approach in which both branches of the adsorption isotherm may be used for the PSD analysis of mesoporous oxide materials. We validate this approach by using Ar data measured at 87 K on the reference set of MCM-41 silica samples (Kruk and Jaroniec, 2000). The generated kernels are smooth, do not show layering transitions and fit accurately the reference data.
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Affiliation(s)
- Jacek Jagiello
- Micromeritics Instrument Corporation, Norcross, GA, USA.
| | - Mietek Jaroniec
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH, USA
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Wang LY, Gu F, Wang HJ, Sun ZL. Pressure Profile for an Associating Lennard-Jones Fluid Confined in a Spherical Cavity. J Phys Chem B 2017; 121:2142-2152. [PMID: 28191841 DOI: 10.1021/acs.jpcb.6b09861] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present the pressure tensor of an associating Lennard-Jones (LJ) fluid confined in a spherical cavity of hard wall, where a high-order density correlation has been taken into account. To give the two-body association potential for calculating the pressure tensor, an angle-average of site-site attraction over all orientations of two particles is performed. Furthermore, the classical density functional theory is employed to obtain the density profile of the confined fluid, by which the normal and tangential pressure profiles are illustrated under various conditions to show the dependence of the pressure tensor on the association strength, number of associating sites, radius of cavity, and bulk density. As an application, the corresponding surface tension is calculated. It is shown that under a strong association interaction (both association strength and the number of associating sites are large), the pressure profiles are depleted from the wall of the cavity instead of the oscillatory behavior under a weak association interaction. Such a tendency is mainly determined by the competition between association interaction and excluded volume interaction. Therefore, the aggregation state and related properties of an associating LJ fluid within a confinement of nanoscale can be efficiently regulated by the association interaction.
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Affiliation(s)
| | | | | | - Zong-Li Sun
- Science and Technology College, North China Electric Power University , Baoding 071051, P. R. China
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Sokołowski S, Kalyuzhnyi YV. Re-entrant Phase Behavior in Confined Two-Patch Colloidal Particles. J Phys Chem B 2014; 118:9076-84. [DOI: 10.1021/jp503826p] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. Sokołowski
- Department
for the Modelling of Physico-Chemical Processes, Faculty
of Chemistry, MCS University, 20031 Lublin, Poland
| | - Y. V. Kalyuzhnyi
- Institute for Condensed Matter Physics, Svientsitskoho 1, 79011 Lviv, Ukraine
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Jagiello J, Olivier JP. Carbon slit pore model incorporating surface energetical heterogeneity and geometrical corrugation. ADSORPTION 2013. [DOI: 10.1007/s10450-013-9517-4] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Wu J. Density functional theory for chemical engineering: From capillarity to soft materials. AIChE J 2006. [DOI: 10.1002/aic.10713] [Citation(s) in RCA: 299] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fu D, Wu J. Vapor−Liquid Equilibria and Interfacial Tensions of Associating Fluids within a Density Functional Theory. Ind Eng Chem Res 2004. [DOI: 10.1021/ie049788a] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dong Fu
- Department of Environmental Engineering, North China Electric Power University, Baoding, P.R. China 071003, and Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521-0425
| | - Jianzhong Wu
- Department of Environmental Engineering, North China Electric Power University, Baoding, P.R. China 071003, and Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521-0425
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Tripathi S, Chapman WG. Density-functional theory for polar fluids at functionalized surfaces. I. Fluid-wall association. J Chem Phys 2003. [DOI: 10.1063/1.1625638] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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SLOVÁK JAN. Adsorption of fluids of pseudo-hard bodies and EPM5 water on solid surface: density functional theory. Mol Phys 2003. [DOI: 10.1080/0026897031000114783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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RESZKO-ZYGMUNT JOANNA, RŻYSKO WOJCIECH, SOKOŁOWSKI STEFAN, SOKOŁOWSKA ZOFIA. The influence of random changes in the adsorbing potential on phase transitions in a Lennard-Jones fluid confined to energetically heterogeneous slit-like pores. Mol Phys 2001. [DOI: 10.1080/00268970110065988] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Reszko-Zygmunt J, Pizio O, Rzysko W, Sokolowski S, Sokolowska Z. Capillary Condensation in Pores with Energetically Heterogeneous Walls: Density Functional versus Monte Carlo Calculations. J Colloid Interface Sci 2001; 241:169-177. [PMID: 11502119 DOI: 10.1006/jcis.2001.7721] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigate adsorption of a Lennard-Jones fluid in slit-like pores with energetically heterogeneous walls by using Grand Canonical Monte Carlo simulations and a density functional approach. The model of a fluid-wall potential is qualitatively similar to that invoked by Röcken et al. (J. Chem. Phys. 108, 8089, (1999); i.e., it consists of a homogeneous part that varies in the direction perpendicular to the wall and a periodic part, varying also in one direction parallel to the wall, but in contrast to the above mentioned work, both parts of the fluid-wall potential are modeled by Lennard-Jones (9, 3) type functions. The structure of the adsorbed film is characterized by local densities. We evaluate the phase diagrams for several systems characterized by different corrugation of the adsorbing potential and discuss the discrepancies between theoretical predictions and computer simulations. Copyright 2001 Academic Press.
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Affiliation(s)
- Joanna Reszko-Zygmunt
- Department for the Modelling of Physico-Chemical Processes, Maria Curie-Sklodowska University, Lublin, 20031, Poland
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Müller EA, Gubbins KE. Molecular-Based Equations of State for Associating Fluids: A Review of SAFT and Related Approaches. Ind Eng Chem Res 2001. [DOI: 10.1021/ie000773w] [Citation(s) in RCA: 551] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Erich A. Müller
- Departamento de Termodinámica y Fenómenos de Transferencia, Universidad Simón Bolívar, Caracas 1080, Venezuela
| | - Keith E. Gubbins
- Department of Chemical Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905
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