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Rodrigues NT, Alves Aarão Reis FD. Adsorption of Diffusing Tracers, Apparent Tortuosity, and Application to Mesoporous Silica. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:11371-11380. [PMID: 38758366 PMCID: PMC11155253 DOI: 10.1021/acs.langmuir.3c03855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/18/2024]
Abstract
The apparent tortuosity due to adsorption of diffusing tracers in a porous material is determined by a scaling approach and is used to analyze recent data on LiCl and alkane diffusion in mesoporous silica. The slope of the adsorption isotherm at small loadings is written as β = qA/qG, where qA is the adsorption-desorption ratio and qG = ϵ/(as) - 1 is a geometrical factor depending on the range a of the tracer-wall interaction, the porosity ϵ, and the specific surface area s. The adsorption leads to a decrease of effective diffusion coefficient, which is quantified by multiplying the geometrical tortuosity factor τgeom by an apparent tortuosity factor τapp. In wide pores or when the adsorption barrier is high, τapp = β + 1, as obtained in previous works, but in narrow pores there is an additional contribution from frequent adsorption-desorption transitions. These results are obtained in media with parallel pores of constant cross sections, where the ratio between the effective pore width ϵ/s and the actual width is ≈0.25. Applications to mesoporous silica samples are justified by the small deviations from this ideal ratio. In the analysis of alkane self-diffusion data, the fractions of adsorbed molecules predicted in a recent theoretical work are used to estimate τgeom of the silica samples, which is ≫1 only in the sample with the narrowest pores (nominal 3 nm). The application of the model to Li+ ion diffusion leads to similar values of τgeom and to a difference of energy barriers of desorption and adsorption for those ions of ∼0.06 eV. Comparatively, alkane self-diffusion provides the correct order of magnitude of τgeom, with adsorption playing a less important role, whereas adsorption effects on Li+ diffusion are much more important.
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Affiliation(s)
- Nathann Teixeira Rodrigues
- Instituto de Física, Universidade Federal Fluminense, Avenida Litorânea s/n, 24210-340 Niterói, RJ, Brazil
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2
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Kikkawa N, Kimura M. Comprehensive Molecular Dynamics Study of Oxygen Diffusion in Carbon Mesopores: Insights for Designing Fuel-Cell Catalyst Supports. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:1674-1687. [PMID: 38198684 DOI: 10.1021/acs.langmuir.3c02627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Mesoporous carbon is often used as a support for platinum catalysts in polymer electrolyte fuel-cell catalyst layers. Mesopores in the carbon support improve the performance of fuel cells by inhibiting the adsorption of ionomer onto the catalyst particles. However, the mesopores may impair mass transport. Hence, understanding molecular behaviors in the pores is essential to optimizing the mesopore structures. Specifically, it is crucial to understand the oxygen transport in the high-current region. In this study, the diffusion coefficients of oxygen molecules in carbon mesopores were calculated for various pore lengths, pore diameters, filling rates, and water contents in the ionomer via molecular dynamics simulations. The results show that oxygen diffusion slows by 2 orders of magnitude because of pore occlusion, and it slows down by an additional 1 or 2 orders of magnitude if ionomers are present in the pores. The occlusion can be theoretically predicted by considering the surface free energy. This theory provides some insight into mesoporous carbon designs; for instance, the theory suggests that narrow pores should be shortened to prevent occlusion. Slow diffusion in the presence of ionomers was attributed to the localization of oxygen at the dense ionomer-carbon interface. Thus, to improve oxygen transport properties, carbon surfaces and ionomer structures may be designed in such a manner as to prevent densification at the interface.
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Affiliation(s)
- Nobuaki Kikkawa
- Toyota Central RD Laboratories, Inc., Yokomichi 41-1, Nagakute 480-1192, Aichi Japan
| | - Masayuki Kimura
- Toyota Motor Corporation, Toyota 1, Toyota 471-8571, Aichi Japan
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3
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Kuzmin V, Safiullin K, Stanislavovas A, Baibekov E, Tagirov M. Diffusion Anisotropy of Gaseous Helium-3 in Ordered Aerogels at Low Temperatures. J Phys Chem B 2023; 127:1459-1470. [PMID: 36740806 DOI: 10.1021/acs.jpcb.2c08251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We report on the first observation of diffusion anisotropy of gaseous helium-3 entrapped in ordered aerogels at 4.2 K. The origins of 3He diffusion anisotropy in aerogels of different porosity are discussed. The correlations between gas diffusion coefficient and basic parameters of aerogels, such as porosity, fiber diameter, and fiber's degree of alignment, are inspected using simple diffusion simulations within the framework of classical diffusion model in both oriented and chaotic aerogels under conditions of diffuse (Knudsen diffusion) and specular reflections of atoms from the walls. The failure of the two-phase and Knudsen diffusion models at low temperature in isotropic and anisotropic aerogels is observed. The effect of a wall attractive potential on the gas dynamics is suspected to play a crucial role in the gas diffusion and its anisotropy. The rough theoretical estimates of that effect at low temperatures in aerogel space confirm this assumption. The observed peculiar diffusion is universal and is expected to occur with other probe gases at higher temperatures.
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Affiliation(s)
| | - Kajum Safiullin
- Institute of Physics, Kazan Federal University, 420008Kazan, Russia
| | | | - Eduard Baibekov
- Institute of Physics, Kazan Federal University, 420008Kazan, Russia
| | - Murat Tagirov
- Institute of Physics, Kazan Federal University, 420008Kazan, Russia.,Tatarstan Academy of Sciences, 420111Kazan, Russia
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Bizon K, Boroń D, Tabiś B. The Steady State Characteristics of Multicomponent Diffusion in Micro- and Mesoporous Media for Adsorbable and Nonadsorbable Species. MEMBRANES 2022; 12:921. [PMID: 36295680 PMCID: PMC9608831 DOI: 10.3390/membranes12100921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/16/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
The study addresses one of the fundamental issues in the mathematical modeling and quantitative process analysis of complex multicomponent diffusion in meso- and microporous materials. The model presented here incorporates combined molecular diffusion, Knudsen diffusion, viscous flow, and surface diffusion. A methodology and algorithm for the determination of steady states of such complex diffusive processes are proposed. The adopted form of the surface diffusion model does not require the calculation of the thermodynamic factor matrix. The method was verified by comparing the profiles of the state variables with those obtained from the dynamic model for sufficiently long diffusion times. The application of the method is illustrated for two diffusion processes involving three components. In the first one, all components are subject to adsorption. In the other, one gaseous component is an inert and is therefore not adsorbed and does not participate in surface diffusion. It is shown that the presence of inerts as well as their number does not impede the application of the proposed algorithm for the determination of steady states.
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Aksu A, Cetintasoglu ME, Taskin OS, Caglar-Balkis N. Development of Low-Cost Silica-Based Core Material for Fire-Resistant Doors of Vessels. RUSS J APPL CHEM+ 2021. [DOI: 10.1134/s1070427221090172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Gao X, Da C, Chen C, Li Z, Gu X, Bhatia SK. The induced orientation effect of linear gases during transport in a NaA zeolite membrane modified by alkali lignin. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2020.118971] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Gao X, Li Z, Chen C, Da C, Liu L, Tian S, Ji G. The Determination of Pore Shape and Interfacial Barrier of Entry for Light Gases Transport in Amorphous TEOS-Derived Silica: A Finite Element Method. ACS APPLIED MATERIALS & INTERFACES 2021; 13:4804-4812. [PMID: 33443400 DOI: 10.1021/acsami.0c20594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The interfacial barrier of entry for light gas transport in a nanopore was a crucial factor to determine the separation efficiency in membrane technologies. To examine this effect, amorphous silica was prepared by sol-gel process, and its characterization results revealed that the commonly used cylindrical pore shape failed to represent the adsorption behavior of gases, but instead the pore shape had to be represented by a slit pore model. A finite element method (FEM) was developed to analyze the interfacial resistance by integrating a Lennard-Jones (LJ) potential over the layer area. It was found that the strong repulsion/attraction at the pore interface could be paired with the motion energy of guest molecules to predict the ideal selectivity between gases, thereby providing a solution to preliminarily screen the separation performance among a host of membrane candidates.
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Affiliation(s)
- Xuechao Gao
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, 30 Puzhu Road (S), Nanjing 210009, China
| | - Zhi Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, 30 Puzhu Road (S), Nanjing 210009, China
| | - Cheng Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, 30 Puzhu Road (S), Nanjing 210009, China
| | - Chao Da
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, 30 Puzhu Road (S), Nanjing 210009, China
| | - Lang Liu
- Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Ministry of Education, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Sen Tian
- State Key Laboratory of Coal Mine Disaster Dynamics and Control, School of Resources and Environmental Science, Chongqing University, Chongqing 400044, China
| | - Guozhao Ji
- School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
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8
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Role of pore geometry in gas separation using nanoporous graphene – A study in contrast between equilibrium and non-equilibrium cases. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Chen H, Snurr RQ. Understanding the Loading Dependence of Adsorbate Diffusivities in Hierarchical Metal-Organic Frameworks. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1372-1378. [PMID: 31957450 DOI: 10.1021/acs.langmuir.9b03802] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using atomistic simulations, we studied the diffusion of n-hexane in a series of isoreticular hierarchical metal-organic frameworks (MOFs) NU-100x. Nonmonotonic diffusivity-loading relationships that depend on the pore sizes were observed, which can be explained by the spatial distribution of adsorbates at different loadings. For one of the MOFs in the series, NU-1000-M, the diffusivity-loading relationship is almost identical to the previously reported results of n-hexane diffusion in the hierarchical self-pillared pentasil (SPP) zeolite. Detailed analysis revealed that the similarity results from their similar micropore and window sizes, which was confirmed by free-energy mapping. The effects of temperature and adsorbate chain length on the diffusion were also studied, which supported our conclusion that the diffusivity in hierarchical nanoporous materials is primarily controlled by the sizes of the micropores and the connecting windows, particularly at relatively low loadings.
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Affiliation(s)
- Haoyuan Chen
- Department of Chemical & Biological Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Randall Q Snurr
- Department of Chemical & Biological Engineering , Northwestern University , Evanston , Illinois 60208 , United States
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Colson F, Barlow DA. Statistical method for modeling Knudsen diffusion in nanopores. Phys Rev E 2020; 100:062125. [PMID: 31962516 DOI: 10.1103/physreve.100.062125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Indexed: 11/07/2022]
Abstract
This paper presents a statistical method for the calculation of gaseous flux and diffusion coefficients through a Knudsen-regime cylindrical nanopore. A general integral formula for the flux is derived in terms of collision frequency, molecular density, and a scattering path length probability distribution. Under appropriate steady-state assumptions, the general formula simplifies to Fick's first law, from which an expression for the diffusion coefficient is derived. The model is shown to be dimensionally consistent with the Einstein relation. The conditions for agreement with Fick's second law are investigated. Using a model probability distribution the model leads to an expression for the diffusion coefficient for a pore of finite length. This result is shown to compare favorably with a classic formula from the literature.
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Affiliation(s)
- Fenner Colson
- Department of Chemistry and Physics, Florida Gulf Coast University, Fort Myers, Florida 33965, USA
| | - D A Barlow
- Alderman Barlow Labs, PO Box 1394 Trenton, Florida 32693, USA
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11
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Sun W, Chen SL, Xu M, Wei Y, Fan TT, Huang LX, Ma B, Guo J. The measurements of the intrinsic diffusivity in pores and surface diffusivity inside the porous materials in liquid phase. Chem Eng Sci 2019. [DOI: 10.1016/j.ces.2018.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Zhu LT, Ma WY, Luo ZH. Influence of distributed pore size and porosity on MTO catalyst particle performance: Modeling and simulation. Chem Eng Res Des 2018. [DOI: 10.1016/j.cherd.2018.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Gao X, Ji G, Wang J, Peng L, Gu X, Chen L. Critical pore dimensions for gases in a BTESE-derived organic-inorganic hybrid silica: A theoretical analysis. Sep Purif Technol 2018. [DOI: 10.1016/j.seppur.2017.09.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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14
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Kim AS, Lee HS, Moon DS, Kim HJ. Self-adjusting, combined diffusion in direct contact and vacuum membrane distillation. J Memb Sci 2017. [DOI: 10.1016/j.memsci.2017.08.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Liu J, Cheng Z, Wei J, Zhang Q, Chen X, Cen Y, Li L. Mean stop paths and diffusion regimes of molecules in one-dimensional zeolite channels. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2017.05.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Kuzmin V, Safiullin K, Stanislavovas A, Tagirov M. Helium-3 gas self-diffusion in a nematically ordered aerogel at low temperatures: enhanced role of adsorption. Phys Chem Chem Phys 2017; 19:23146-23153. [PMID: 28820197 DOI: 10.1039/c7cp03949b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We performed 3He gas diffusion measurements for the first time in a highly porous ordered Al2O3 aerogel sample at a temperature of 4.2 K using a nuclear magnetic resonance field gradient technique. A strong influence of 3He adsorption in the aerogel on self-diffusion is observed. The classical consideration of adsorptive gas diffusion in mesopores leads to anomalously high tortuosity factors. The application of a more sophisticated model than the simple combination of empirical two-phase diffusion and the Knudsen gas diffusion models is required to explain our results. Anisotropic properties of the aerogel are not reflected in the observed gas diffusion even at low gas densities where the anisotropic Knudsen regime of diffusion is expected. The observed gas densification indicates the influence of the aerogel attractive potential on the molecular dynamics, which probably explains the reduced diffusion process. Perhaps this behavior is common for any adsorptive gases in nanopores.
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Affiliation(s)
| | - Kajum Safiullin
- Kazan Federal University, Kazan, 420008, Russian Federation. and Institute of Perspective Research, Academy of Sciences of the Republic of Tatarstan, Kazan 420111, Russia
| | | | - Murat Tagirov
- Kazan Federal University, Kazan, 420008, Russian Federation. and Institute of Perspective Research, Academy of Sciences of the Republic of Tatarstan, Kazan 420111, Russia
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17
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Pore-neck resistance to light gases in a microporous BTESE-derived silica: A comparison of membrane and xerogel powder. J Memb Sci 2017. [DOI: 10.1016/j.memsci.2017.02.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Bhatia SK. Characterizing Structural Complexity in Disordered Carbons: From the Slit Pore to Atomistic Models. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:831-847. [PMID: 27996264 DOI: 10.1021/acs.langmuir.6b03459] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The reliable characterization of nanoporous carbons is critical to the design and optimization of their numerous applications; however, the vast majority of carbons in industrial use are highly disordered, with complex structures whose understanding has long challenged researchers. The idealized slit pore model represents the most commonly used approximation to a carbon nanopore; nevertheless, it has been only partially successful in predicting adsorption isotherms and fails significantly in predicting transport properties because of its inability to capture structural disorder and its effect on fluid accessibility. Atomistic modeling of the structure has much potential for overcoming this limitation, and among such approaches, hybrid reverse Monte Carlo simulation has emerged as the most attractive. This method reconstructs the structure of a carbon based on the fitting of its experimentally measured pair distribution function and appropriate properties such as porosity while minimizing the energy. The method is shown to be best implemented using a multistage strategy, with the first stage used to attain a deep minimum of the energy and subsequent stages to refine the structure based on the fitting of specific properties. Methods to determine the accessibility of gases based on the atomistic structure are outlined, and it is shown that energy barriers are very sensitive to small differences in the sizes of constrictions and pore entries. The ability to accurately predict macroscopic transport coefficients of adsorbates in nanoporous carbons appears to be the greatest limitation of such models. Overcoming this will require the fitting of properties more sensitive to long-range disorder than the currently used pair distribution and the use of a suitable multiscaling strategy, which is suggested as a future direction for advancing atomistic models. The inclusion of heteroatoms in the structure is also an important area requiring further attention, particularly in the development of computationally efficient force fields incorporating their interactions.
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Affiliation(s)
- Suresh K Bhatia
- School of Chemical Engineering, The University of Queensland , St. Lucia, QLD 4072, Australia
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19
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Besser B, Ahmed A, Baune M, Kroll S, Thöming J, Rezwan K. Applying Alkyl-Chain Surface Functionalizations in Mesoporous Inorganic Structures: Their Impact on Gas Flow and Selectivity Depending on Temperature. ACS APPLIED MATERIALS & INTERFACES 2016; 8:26938-26947. [PMID: 27636163 DOI: 10.1021/acsami.6b09174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Porous inorganic capillary membranes are prepared to serve as model structures for the experimental investigation of the gas transport in functionalized mesopores. The porous structures possess a mean pore diameter of 23 nm which is slightly reduced to 20 nm after immobilizing C16-alkyl chains on the surface. Gas permeation measurements are performed at temperatures ranging from 0 to 80 °C using Ar, N2, and CO2. Nonfunctionalized structures feature a gas transport according to Knudsen diffusion with regard to gas flow and selectivity. After C16-functionalization, the gas flow is reduced by a factor of 10, and the ideal selectivities deviate from the Knudsen theory. CO2 adsorption measurements show a decrease in total amount of adsorbed gas and isosteric heat of adsorption. It is hypothesized that the immobilized C16-chains sterically influence the gas transport behavior without a contribution from adsorption effects. The reduced gas flow derives from an additional surface resistance caused by the C16-chains spacially limiting the adsorption and desorption directions for gas molecules propagating through the structure, resulting in longer diffusion paths. In agreement, the gas flow is found to correlate with the molecular diameter of the gas species (CO2 < Ar < N2) increasing the resistance for larger molecules. This affects the ideal selectivities with the relation [Formula: see text]. The influence on selectivity increases with increasing temperature which leads to the conclusion that the temperature induced movement of the C16-chains is responsible for the stronger interaction between gas molecules and surface functional groups.
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Affiliation(s)
- Benjamin Besser
- Advanced Ceramics, University of Bremen , Am Biologischen Garten 2, 28359 Bremen, Germany
| | - Atiq Ahmed
- Advanced Ceramics, University of Bremen , Am Biologischen Garten 2, 28359 Bremen, Germany
| | - Michael Baune
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen , Leobener Strasse 1, 28359 Bremen, Germany
| | - Stephen Kroll
- Advanced Ceramics, University of Bremen , Am Biologischen Garten 2, 28359 Bremen, Germany
- Centre for Materials and Processes (MAPEX), University of Bremen , Bibliothekstraße 1, 28359 Bremen, Germany
| | - Jorg Thöming
- Center for Environmental Research and Sustainable Technology (UFT), University of Bremen , Leobener Strasse 1, 28359 Bremen, Germany
- Centre for Materials and Processes (MAPEX), University of Bremen , Bibliothekstraße 1, 28359 Bremen, Germany
| | - Kurosch Rezwan
- Advanced Ceramics, University of Bremen , Am Biologischen Garten 2, 28359 Bremen, Germany
- Centre for Materials and Processes (MAPEX), University of Bremen , Bibliothekstraße 1, 28359 Bremen, Germany
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Krishna R. Investigating the Validity of the Knudsen Diffusivity Prescription for Mesoporous and Macroporous Materials. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.6b00762] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rajamani Krishna
- Van ‘t Hoff Institute
for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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21
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Abstract
This review presents the state-of-the-art of multiscale adsorption and transport in hierarchical porous materials.
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Affiliation(s)
- Benoit Coasne
- Université Grenoble Alpes
- LIPHY
- F-38000 Grenoble
- France
- CNRS
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22
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Ji G, Smart S, Bhatia SK, Diniz da Costa JC. Improved pore connectivity by the reduction of cobalt oxide silica membranes. Sep Purif Technol 2015. [DOI: 10.1016/j.seppur.2015.09.065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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23
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24
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Jacob JDC, He K, Retterer ST, Krishnamoorti R, Conrad JC. Diffusive dynamics of nanoparticles in ultra-confined media. SOFT MATTER 2015; 11:7515-24. [PMID: 26278883 DOI: 10.1039/c5sm01437a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Differential dynamic microscopy (DDM) was used to investigate the diffusive dynamics of nanoparticles of diameter 200-400 nm that were strongly confined in a periodic square array of cylindrical nanoposts. The minimum distance between posts was 1.3-5 times the diameter of the nanoparticles. The image structure functions obtained from the DDM analysis were isotropic and could be fit by a stretched exponential function. The relaxation time scaled diffusively across the range of wave vectors studied, and the corresponding scalar diffusivities decreased monotonically with increased confinement. The decrease in diffusivity could be described by models for hindered diffusion that accounted for steric restrictions and hydrodynamic interactions. The stretching exponent decreased linearly as the nanoparticles were increasingly confined by the posts. Together, these results are consistent with a picture in which strongly confined nanoparticles experience a heterogeneous spatial environment arising from hydrodynamics and volume exclusion on time scales comparable to cage escape, leading to multiple relaxation processes and Fickian but non-Gaussian diffusive dynamics.
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Affiliation(s)
- Jack Deodato C Jacob
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4004, USA.
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25
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Vargas EL, Snurr RQ. Heterogeneous Diffusion of Alkanes in the Hierarchical Metal-Organic Framework NU-1000. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:10056-10065. [PMID: 26302209 DOI: 10.1021/acs.langmuir.5b02420] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The metal-organic framework (MOF) NU-1000 is a hierarchical material that comprises both micropores and mesopores in its crystalline structure. Because the pore structure is perfectly defined, NU-1000 is an interesting material for improving our understanding of diffusion in hierarchically structured materials. Here, we present molecular dynamics simulations aimed at probing the transport properties of n-alkanes in NU-1000 and introduce methods from the microrheology literature for analyzing the mean-squared displacements and their spatial heterogeneity. Adsorption occurs initially in the smaller channels, and diffusion at low loading is limited by interaction between adsorbate and framework atoms. The larger channels provide a region of low density where molecules are able to diffuse at higher rates predominantly along the channel axes. The disparate size of the channels gives rise to heterogeneity in the diffusivity of the guest molecules, whereas the asymmetry of the channels leads to anisotropic diffusion. Together, the channels form a network of "highways" and "side streets" that provide enhanced diffusion in one dimension.
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Affiliation(s)
- Ernesto L Vargas
- Department of Chemical and Biological Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Randall Q Snurr
- Department of Chemical and Biological Engineering, Northwestern University , Evanston, Illinois 60208, United States
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26
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Ranganathan R, Rokkam S, Desai T, Keblinski P, Cross P, Burnes R. Modeling high-temperature diffusion of gases in micro and mesoporous amorphous carbon. J Chem Phys 2015; 143:084701. [DOI: 10.1063/1.4928633] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Raghavan Ranganathan
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
| | - Srujan Rokkam
- Advanced Cooling Technologies, Inc., 1046 New Holland Ave., Lancaster, Pennsylvania 17601, USA
| | - Tapan Desai
- Advanced Cooling Technologies, Inc., 1046 New Holland Ave., Lancaster, Pennsylvania 17601, USA
| | - Pawel Keblinski
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
| | - Peter Cross
- Naval Air Warfare Center, 1900 Knox Road, China Lake, California 93555, USA
| | - Richard Burnes
- Naval Air Warfare Center, 1900 Knox Road, China Lake, California 93555, USA
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Kim HJ, Brunelli NA, Brown AJ, Jang KS, Kim WG, Rashidi F, Johnson JR, Koros WJ, Jones CW, Nair S. Silylated mesoporous silica membranes on polymeric hollow fiber supports: synthesis and permeation properties. ACS APPLIED MATERIALS & INTERFACES 2014; 6:17877-17886. [PMID: 25255051 DOI: 10.1021/am504581j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report the synthesis and organic/water separation properties of mesoporous silica membranes, supported on low-cost and scalable polymeric (polyamide-imide) hollow fibers, and modified by trimethylsilylation with hexamethyldisilazane. Thin (∼1 μm) defect-free membranes are prepared, with high room-temperature gas permeances (e.g., 20,000 GPU for N2). The membrane morphology is characterized by multiple techniques, including SEM, TEM, XRD, and FT-ATR spectroscopy. Silylation leads to capping of the surface silanol groups in the mesopores with trimethylsilyl groups, and does not affect the integrity of the mesoporous silica structure and the underlying hollow fiber. The silylated membranes are evaluated for pervaporative separation of ethanol (EtOH), methylethyl ketone (MEK), ethyl acetate (EA), iso-butanol (i-BuOH), and n-butanol (n-BuOH) from their dilute (5 wt %) aqueous solutions. The membranes show separation factors in the range of 4-90 and high organic fluxes in the range of 0.18-2.15 kg m(-2) h(-1) at 303 K. The intrinsic selectivities (organic/water permeability ratios) of the silylated membranes at 303 K are 0.33 (EtOH/water), 0.5 (MEK/water), 0.25 (EA/water), 1.25 (i-BuOH/water), and 1.67 (n-BuOH/water) respectively, in comparison to 0.05, 0.015, 0.005, 0.08, and 0.14 for the unmodified membranes. The silylated membranes allow upgradation of water/organics feeds to permeate streams with considerably higher organics content. The selective and high-flux separation is attributed to both the organophilic nature of the modified mesopores and the large effective pore size. Comparison with other organics/water separation membranes reveals that the present membranes show promise due to high flux, use of scalable and low-cost supports, and good separation factors that can be further enhanced by tailoring the mesopore silylation chemistry.
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Affiliation(s)
- Hyung-Ju Kim
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive, Atlanta, Georgia 30332-0100, United States
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Roldughin VI, Kharitonova TV, Shalygin MG. On local entropy production in gases and gaseous mixtures flowing though nanosized channels. COLLOID JOURNAL 2014. [DOI: 10.1134/s1061933x14030144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Farmahini AH, Shahtalebi A, Jobic H, Bhatia SK. Influence of Structural Heterogeneity on Diffusion of CH 4 and CO 2 in Silicon Carbide-Derived Nanoporous Carbon. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2014; 118:11784-11798. [PMID: 24932319 PMCID: PMC4051255 DOI: 10.1021/jp502929k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/07/2014] [Indexed: 06/03/2023]
Abstract
We investigate the influence of structural heterogeneity on the transport properties of simple gases in a Hybrid Reverse Monte Carlo (HRMC) constructed model of silicon carbide-derived carbon (SiC-DC). The energy landscape of the system is determined based on free energy analysis of the atomistic model. The overall energy barriers of the system for different gases are computed along with important properties, such as Henry constant and differential enthalpy of adsorption at infinite dilution, and indicate hydrophobicity of the SiC-DC structure and its affinity for CO2 and CH4 adsorption. We also study the effect of molecular geometry, pore structure and energy heterogeneity considering different hopping scenarios for diffusion of CO2 and CH4 through ultramicropores using the Nudged Elastic Band (NEB) method. It is shown that the energy barrier of a hopping molecule is very sensitive to the shape of the pore entry. We provide evidence for the influence of structural heterogeneity on self-diffusivity of methane and carbon dioxide using molecular dynamics simulation, based on a maximum in the variation of self-diffusivity with loading. A comparison of the MD simulation results with self-diffusivities from quasi-elastic neutron scattering (QENS) measurements and, with macroscopic uptake-based low-density transport coefficients, reveals the existence of internal barriers not captured in MD simulation and QENS experiments. Nevertheless, the simulation and macroscopic uptake-based diffusion coefficients agree within a factor of 2-3, indicating that our HRMC model structure captures most of the important energy barriers affecting the transport of CH4 in the nanostructure of SiC-DC.
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Affiliation(s)
- Amir H. Farmahini
- School
of Chemical Engineering, The University
of Queensland, QLD 4072, Australia
| | - Ali Shahtalebi
- School
of Chemical Engineering, The University
of Queensland, QLD 4072, Australia
| | - Hervé Jobic
- Institut
de Recherches sur la Catalyse et l’Environnement de Lyon, CNRS, Université Lyon 1, 2 Ave. Albert Einstein, 69626 Villeurbanne, France
| | - Suresh K. Bhatia
- School
of Chemical Engineering, The University
of Queensland, QLD 4072, Australia
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Gao X, Diniz da Costa JC, Bhatia SK. Adsorption and transport of gases in a supported microporous silica membrane. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2014.02.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gao X, Diniz da Costa JC, Bhatia SK. Understanding the diffusional tortuosity of porous materials: An effective medium theory perspective. Chem Eng Sci 2014. [DOI: 10.1016/j.ces.2013.09.050] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Mehlhorn D, Inayat A, Schwieger W, Valiullin R, Kärger J. Probing Mass Transfer in Mesoporous Faujasite-Type Zeolite Nanosheet Assemblies. Chemphyschem 2014; 15:1681-6. [DOI: 10.1002/cphc.201301133] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Indexed: 11/10/2022]
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Adloo H, Esfahany MN, Ehsani MR. Pore network simulation for diffusion through a porous membrane: A comparison between Knudsen and Oscillator models. CAN J CHEM ENG 2013. [DOI: 10.1002/cjce.21960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hadi Adloo
- Department of Chemical Engineering; Isfahan University of Technology; Isfahan Iran
| | - Mohsen Nasr Esfahany
- Department of Chemical Engineering; Isfahan University of Technology; Isfahan Iran
| | - Mohammad Reza Ehsani
- Department of Chemical Engineering; Isfahan University of Technology; Isfahan Iran
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Bonilla MR, Titze T, Schmidt F, Mehlhorn D, Chmelik C, Valiullin R, Bhatia SK, Kaskel S, Ryoo R, Kärger J. Diffusion Study by IR Micro-Imaging of Molecular Uptake and Release on Mesoporous Zeolites of Structure Type CHA and LTA. MATERIALS 2013; 6:2662-2688. [PMID: 28811401 PMCID: PMC5521224 DOI: 10.3390/ma6072662] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 06/12/2013] [Accepted: 06/17/2013] [Indexed: 01/12/2023]
Abstract
The presence of mesopores in the interior of microporous particles may significantly improve their transport properties. Complementing previous macroscopic transient sorption experiments and pulsed field gradient NMR self-diffusion studies with such materials, the present study is dedicated to an in-depth study of molecular uptake and release on the individual particles of mesoporous zeolitic specimens, notably with samples of the narrow-pore structure types, CHA and LTA. The investigations are focused on determining the time constants and functional dependences of uptake and release. They include a systematic variation of the architecture of the mesopores and of the guest molecules under study as well as a comparison of transient uptake with blocked and un-blocked mesopores. In addition to accelerating intracrystalline mass transfer, transport enhancement by mesopores is found to be, possibly, also caused by a reduction of transport resistances on the particle surfaces.
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Affiliation(s)
- Mauricio Rincon Bonilla
- Faculty of Physics and Earth Science, University of Leipzig, Linnéstr. 5, D-04103 Leipzig, Germany.
- School of Chemical Engineering, University of Queensland, Brisbane QLD 4072, Australia.
| | - Tobias Titze
- Faculty of Physics and Earth Science, University of Leipzig, Linnéstr. 5, D-04103 Leipzig, Germany.
| | - Franz Schmidt
- Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden, Germany.
| | - Dirk Mehlhorn
- Faculty of Physics and Earth Science, University of Leipzig, Linnéstr. 5, D-04103 Leipzig, Germany.
| | - Christian Chmelik
- Faculty of Physics and Earth Science, University of Leipzig, Linnéstr. 5, D-04103 Leipzig, Germany.
| | - Rustem Valiullin
- Faculty of Physics and Earth Science, University of Leipzig, Linnéstr. 5, D-04103 Leipzig, Germany.
| | - Suresh K Bhatia
- School of Chemical Engineering, University of Queensland, Brisbane QLD 4072, Australia.
| | - Stefan Kaskel
- Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden, Germany.
| | - Ryong Ryoo
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701, Korea.
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea.
| | - Jörg Kärger
- Faculty of Physics and Earth Science, University of Leipzig, Linnéstr. 5, D-04103 Leipzig, Germany.
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Gao X, Bonilla MR, da Costa JC, Bhatia SK. The transport of gases in a mesoporous γ-alumina supported membrane. J Memb Sci 2013. [DOI: 10.1016/j.memsci.2012.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Kim HJ, Jang KS, Galebach P, Gilbert C, Tompsett G, Conner WC, Jones CW, Nair S. Seeded growth, silylation, and organic/water separation properties of MCM-48 membranes. J Memb Sci 2013. [DOI: 10.1016/j.memsci.2012.10.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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40
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Kärger J, Valiullin R. Mass transfer in mesoporous materials: the benefit of microscopic diffusion measurement. Chem Soc Rev 2013; 42:4172-97. [DOI: 10.1039/c3cs35326e] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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41
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Bhatia SK, Nicholson D. On the non-equilibrium nature of the nanopore fluid. MOLECULAR SIMULATION 2012. [DOI: 10.1080/08927022.2012.685942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Shi Y, Lee YT, Kim AS. Knudsen Diffusion Through Cylindrical Tubes of Varying Radii: Theory and Monte Carlo Simulations. Transp Porous Media 2012. [DOI: 10.1007/s11242-012-9966-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Zeigermann P, Naumov S, Mascotto S, Kärger J, Smarsly BM, Valiullin R. Diffusion in hierarchical mesoporous materials: applicability and generalization of the fast-exchange diffusion model. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:3621-3632. [PMID: 22260082 DOI: 10.1021/la2047432] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Transport properties of cyclohexane confined to a silica material with an ordered, bimodal pore structure have been studied by means of pulsed field gradient nuclear magnetic resonance. A particular organization of the well-defined pore structure, composed of a collection of spatially ordered, spherical mesopores interconnected via narrow worm-like pores, allowed for a quantitative analysis of the diffusion process in a medium with spatially ordered distribution of the fluid density for a broad range of the gas-liquid equilibria. The measured diffusion data were interpreted in terms of effective diffusivities, which were determined within a microscopic model considering long-range molecular trajectories constructed by assembling the alternating pieces of displacement in the two constituting pore spaces. It has further been found that for the system under study, in particular, and for mesoporous materials with multiple porosities, in general, this generalized model simplifies to the conventional fast-exchange model used in the literature. Thus, not only was justification of the applicability of the fast-exchange model to a diversity of mesoporous materials provided, but the diffusion parameters entering the fast-exchange model were also exactly defined. The equation resulting in this way was found to nicely reproduce the experimentally determined diffusivities, establishing a methodology for targeted fine-tuning of transport properties of fluids in hierarchical materials with multiple porosities.
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Affiliation(s)
- P Zeigermann
- Institute for Experimental Physics I, University of Leipzig, Leipzig, Germany
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A Survey of Multicomponent Mass Diffusion Flux Closures for Porous Pellets: Mass and Molar Forms. Transp Porous Media 2012. [DOI: 10.1007/s11242-012-9946-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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45
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Krishna R, van Baten JM. Investigating the validity of the Bosanquet formula for estimation of diffusivities in mesopores. Chem Eng Sci 2012. [DOI: 10.1016/j.ces.2011.11.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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46
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Petropoulos J, Papadokostaki K. May the Knudsen equation be legitimately, or at least usefully, applied to dilute adsorbable gas flow in mesoporous media? Chem Eng Sci 2012. [DOI: 10.1016/j.ces.2011.09.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Solsvik J, Jakobsen HA. Impacts on the Reactor Performance of Intra-Particle Multicomponent Mass Diffusion Limitations: Knudsen Diffusion. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.egypro.2012.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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49
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Ukmar T, Maver U, Planinšek O, Pintar A, Kaučič V, Godec A, Gaberšček M. Guest–host van der Waals interactions decisively affect the molecular transport in mesoporous media. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm13493k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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The low-density diffusion coefficient of soft-sphere fluids in nanopores: Accurate correlations from exact theory and criteria for applicability of the Knudsen model. J Memb Sci 2011. [DOI: 10.1016/j.memsci.2011.08.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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