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Abstract
AbstractNanoporous solids are ubiquitous in chemical, energy, and environmental processes, where controlled transport of molecules through the pores plays a crucial role. They are used as sorbents, chromatographic or membrane materials for separations, and as catalysts and catalyst supports. Defined as materials where confinement effects lead to substantial deviations from bulk diffusion, nanoporous materials include crystalline microporous zeotypes and metal–organic frameworks (MOFs), and a number of semi-crystalline and amorphous mesoporous solids, as well as hierarchically structured materials, containing both nanopores and wider meso- or macropores to facilitate transport over macroscopic distances. The ranges of pore sizes, shapes, and topologies spanned by these materials represent a considerable challenge for predicting molecular diffusivities, but fundamental understanding also provides an opportunity to guide the design of new nanoporous materials to increase the performance of transport limited processes. Remarkable progress in synthesis increasingly allows these designs to be put into practice. Molecular simulation techniques have been used in conjunction with experimental measurements to examine in detail the fundamental diffusion processes within nanoporous solids, to provide insight into the free energy landscape navigated by adsorbates, and to better understand nano-confinement effects. Pore network models, discrete particle models and synthesis-mimicking atomistic models allow to tackle diffusion in mesoporous and hierarchically structured porous materials, where multiscale approaches benefit from ever cheaper parallel computing and higher resolution imaging. Here, we discuss synergistic combinations of simulation and experiment to showcase theoretical progress and computational techniques that have been successful in predicting guest diffusion and providing insights. We also outline where new fundamental developments and experimental techniques are needed to enable more accurate predictions for complex systems.
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Likhomanova P, Kalashnikov I. Analytic description of anomalous diffusion in heterogeneous environments: Fokker-Planck equation without fractional derivatives. Phys Rev E 2020; 102:022108. [PMID: 32942441 DOI: 10.1103/physreve.102.022108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 07/14/2020] [Indexed: 11/07/2022]
Abstract
This article presents a one-dimensional model of diffusion in a heterogeneous environment, which qualitatively reflects the transport properties of a polymeric membrane with carbon nanotube areas. We derive the Fokker-Planck equation from a system of stochastic equations using a diffusion regime in polymers and a ballistic diffusion regime in nanotube areas. We demonstrate how the probability density function changes in the presence of nanotubes. The mean-square displacement of nonlinear time dependence is observed, indicating anomalous diffusion. This model explains the mechanism of anomalous diffusion in a ballistic-diffusion regime. Our approach does not suppose any type of distribution and does not use a fractional differentiate apparatus.
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Affiliation(s)
- Polina Likhomanova
- National Research Center "Kurchatov Institute," 1 Akademika Kurchatova sq., Moscow, 123182, Russia
| | - Ilia Kalashnikov
- Keldysh Institute of Applied Mathematics, 4 Miusskaya sq., Moscow, 125047, Russia
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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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El-Zanati E, Abdallah H. Esterification of ethyl hexanoic acid using flow-through catalytic membrane reactor. CATALYSIS IN INDUSTRY 2015. [DOI: 10.1134/s2070050415020038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Rasoulian S, Ricardez-Sandoval LA. Uncertainty analysis and robust optimization of multiscale process systems with application to epitaxial thin film growth. Chem Eng Sci 2014. [DOI: 10.1016/j.ces.2014.05.027] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Sheng T, Chen H, Xiong S, Chen X, Wang Y. Atomic layer deposition of polyimide on microporous polyethersulfone membranes for enhanced and tunable performances. AIChE J 2014. [DOI: 10.1002/aic.14553] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ting Sheng
- State Key Laboratory of Materials-Oriented Chemical Engineering; College of Chemistry and Chemical Engineering, Nanjing Tech University (Formerly Nanjing University of Technology); Nanjing 210009 P.R. China
| | - He Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering; College of Chemistry and Chemical Engineering, Nanjing Tech University (Formerly Nanjing University of Technology); Nanjing 210009 P.R. China
| | - Sen Xiong
- State Key Laboratory of Materials-Oriented Chemical Engineering; College of Chemistry and Chemical Engineering, Nanjing Tech University (Formerly Nanjing University of Technology); Nanjing 210009 P.R. China
| | - Xiaoqiang Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering; College of Chemistry and Chemical Engineering, Nanjing Tech University (Formerly Nanjing University of Technology); Nanjing 210009 P.R. China
| | - Yong Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering; College of Chemistry and Chemical Engineering, Nanjing Tech University (Formerly Nanjing University of Technology); Nanjing 210009 P.R. China
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Koltsova EM, Povetkin AD, Tran HQ, Bkhandari ER. Molecular dynamics description of mass transfer in membrane nanopores. THEORETICAL FOUNDATIONS OF CHEMICAL ENGINEERING 2014. [DOI: 10.1134/s0040579514030075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Chempath S, Düren T, Sarkisov L, Snurr RQ. Experiences with the publicly available multipurpose simulation code, Music. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2013.819103] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Feng H, Gao W, Sun Z, Lei B, Li G, Chen L. Molecular Dynamics Simulation of Diffusion and Structure of Some n-Alkanes in near Critical and Supercritical Carbon Dioxide at Infinite Dilution. J Phys Chem B 2013; 117:12525-34. [DOI: 10.1021/jp401824d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Huajie Feng
- School
of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, People’s Republic of China
| | - Wei Gao
- KLGHEI
of Environment and Energy Chemistry, School of Chemistry and Chemical
Engineering, Sun Yat-sen University, Guangzhou 510275, People’s Republic of China
| | - Zhenfan Sun
- School
of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, People’s Republic of China
| | - Bingxin Lei
- School
of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, People’s Republic of China
| | - Gaonan Li
- School
of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, People’s Republic of China
| | - Liuping Chen
- KLGHEI
of Environment and Energy Chemistry, School of Chemistry and Chemical
Engineering, Sun Yat-sen University, Guangzhou 510275, People’s Republic of China
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Feng H, Gao W, Sun Z, Chen L, Lüdemann HD, Lei B, Li G. The self-diffusion and hydrogen bond interaction in neat liquid alkanols: a molecular dynamic simulation study. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2013.841906] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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MD simulation of self-diffusion and structure in some n-alkanes over a wide temperature range at high pressures. J Mol Model 2012; 19:73-82. [DOI: 10.1007/s00894-012-1514-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 06/20/2012] [Indexed: 11/27/2022]
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Kavalenka MN, Striemer CC, Fang DZ, Gaborski TR, McGrath JL, Fauchet PM. Ballistic and non-ballistic gas flow through ultrathin nanopores. NANOTECHNOLOGY 2012; 23:145706. [PMID: 22433182 DOI: 10.1088/0957-4484/23/14/145706] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We show that ultrathin porous nanocrystalline silicon membranes exhibit gas permeance that is several orders of magnitude higher than other membranes. Using these membranes, gas flow obeying Knudsen diffusion has been studied in pores with lengths and diameters in the tens of nanometers regime. The components of the flow due to ballistic transport and transport after reflection from the pore walls were separated and quantified as a function of pore diameter. These results were obtained in pores made in silicon. We demonstrate that changing the pore interior to carbon leads to flow enhancement resulting from a change in the nature of molecule-pore wall interactions. This result confirms previously published flow enhancement results obtained in carbon nanotubes.
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Affiliation(s)
- M N Kavalenka
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY 14627, USA
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Carbon nanotube enhanced membrane distillation for simultaneous generation of pure water and concentrating pharmaceutical waste. Sep Purif Technol 2012. [DOI: 10.1016/j.seppur.2012.02.042] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Application of a flow-through catalytic membrane reactor (FTCMR) for the destruction of a chemical warfare simulant. J Memb Sci 2011. [DOI: 10.1016/j.memsci.2011.04.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Dafinone MI, Feng G, Brugarolas T, Tettey KE, Lee D. Mechanical reinforcement of nanoparticle thin films using atomic layer deposition. ACS NANO 2011; 5:5078-5087. [PMID: 21557541 DOI: 10.1021/nn201167j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Thin films composed of nanoparticles exhibit synergistic properties, making them useful for numerous advanced applications. Nanoparticle thin films (NTFs), however, have a very low resistance to mechanical loading and abrasion, presenting a major bottleneck to their widespread use and commercialization. High-temperature sintering has been shown to improve the mechanical durability of NTFs on inorganic substrates; however, these high-temperature processes are not amenable to organic substrates. In this study, we demonstrate that the mechanical durability of TiO(2)/SiO(2) nanoparticle layer-by-layer (LbL) films on glass and polycarbonate substrates can be drastically improved using atomic layer deposition (ALD) at a relatively low temperature. The structure and physical properties of ALD-treated TiO(2)/SiO(2) nanoparticle LbL films are studied using spectroscopic ellipsometry, UV-vis spectroscopy, contact angle measurements, and nanoindentation. The composition of TiO(2)/SiO(2) LbL films as a function of ALD-cycle number is determined through solution ellipsometry, enabling the determination of the characteristic pore size of nanoparticle thin films. Mechanical durability is also investigated by abrasion tests, showing that the robustness of ALD-treated nanoparticle films is comparable to that of thermally calcined films. More importantly, ALD-treated nanoparticle films retain the original functionality of the TiO(2)/SiO(2) LbL films, such as superhydrophilicity and antireflection properties, demonstrating the utility of ALD as a reinforcement method for nanoparticle thin films.
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Affiliation(s)
- Majemite I Dafinone
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Gethard K, Sae-Khow O, Mitra S. Water desalination using carbon-nanotube-enhanced membrane distillation. ACS APPLIED MATERIALS & INTERFACES 2011; 3:110-114. [PMID: 21188976 DOI: 10.1021/am100981s] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Carbon nanotube (CNT) enhanced membrane distillation is presented for water desalination. It is demonstrated that the immobilization of the CNTs in the pores of a hydrophobic membrane favorably alters the water-membrane interactions to promote vapor permeability while preventing liquid penetration into the membrane pores. For a salt concentration of 34 000 mg L(-1) and at 80 °C, the nanotube incorporation led to 1.85 and 15 times increase in flux and salt reduction, respectively.
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DEULKAR SUNDEEPH, YO HWEIJANG, HUANG JOWLAY. TEM-BASED INVESTIGATIONS ON CVD-ASSISTED GROWTH OF ZnO NANOWIRES INSIDE NANOCHANNELS OF ANODIZED ALUMINUM OXIDE TEMPLATE. INTERNATIONAL JOURNAL OF NANOSCIENCE 2010. [DOI: 10.1142/s0219581x10006600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The role of Chemical Vapor Deposition's (CVD) temperature and time duration on the mass transport properties and repercussions of these properties on the crystalline growth of ZnO nanowires inside Anodic Aluminum Oxide (AAO) nanotubes (aspect ratio = 1500) have been investigated. CVD assisted growth of nanowires in AAO nanochannels was carried out for 27 min at deposition temperature of 813 K (A1) and for 180 min at 903 K (A2) under identical gas flow rates ( Ar : 23 sccm and O2 : 0.45 sccm) under a chamber pressure of 4.45 torr. Electron diffraction patterns (SAED) of the ZnO diffused inside A1 nanotube (exposed in Focused Ion Beam milled cross-sections) showed a ringed pattern, signifying polycrystalline morphology at the tip as well as the channel bottom. For A2, a single crystal formation at least in the tip region was confirmed by the SAED pattern while the corresponding High Resolution TEM image (HRTEM) revealed a lattice spacing of 0.24 nm corresponding to the (1 0 1) growth direction of zincite (JCPDS-36-1451). Chemical composition of the nanowires, reflected the inherent stoichiometry of preferentially nucleated ZnO in the grooved orifices of individual nanopores. Data points of normalised values of the Zn concentration (TEM-EDS line scan) versus penetration depth (~ 0.6 μm), were empirically fitted with solutions of modified Fickian diffusion equation in 1-D. The Diffusion coefficient values of the order of 0.06 nm2 s-1 and 0.22 nm2 s-1 were obtained for ZnO flow inside nanochannels of A1 and A2, respectively. Observed variations, in diffusivity and relative density, have been explained qualitatively by considering the transport of ZnO inside the nanochannels as arising from superposition of the temperature dependent contributions of the convectional viscous creep and surface diffusion components.
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Affiliation(s)
- SUNDEEP H. DEULKAR
- Department of Material Science and Engineering, National Cheng Kung University, No. 1 Ta-Hsueh Road, Tainan 701, Taiwan, R.O.C
- Department of Physics, Royal College of Arts, Commerce and Science, Shristi Complex Mira Road, Thane-401 104, India
| | - HWEI-JANG YO
- Department of Physics, National Cheng Kung University, No.1 Ta-Hsueh Road, Tainan 701, Taiwan, R.O.C
| | - JOW-LAY HUANG
- Department of Material Science and Engineering, National Cheng Kung University, No. 1 Ta-Hsueh Road, Tainan 701, Taiwan, R.O.C
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Krishna R, van Baten J. An investigation of the characteristics of Maxwell–Stefan diffusivities of binary mixtures in silica nanopores. Chem Eng Sci 2009. [DOI: 10.1016/j.ces.2008.10.045] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Albo SE, Snurr RQ, Broadbelt LJ. Designing Nanostructured Membranes for Oxidative Dehydrogenation of Alkanes Using Kinetic Modeling. Ind Eng Chem Res 2008. [DOI: 10.1021/ie800043f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simón E. Albo
- Department of Chemical and Biological Engineering and Institute for Catalysis in Energy Processes, Northwestern University, Evanston, Illinois 60208
| | - Randall Q. Snurr
- Department of Chemical and Biological Engineering and Institute for Catalysis in Energy Processes, Northwestern University, Evanston, Illinois 60208
| | - Linda J. Broadbelt
- Department of Chemical and Biological Engineering and Institute for Catalysis in Energy Processes, Northwestern University, Evanston, Illinois 60208
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Celestini F, Mortessagne F. Cosine law at the atomic scale: toward realistic simulations of Knudsen diffusion. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:021202. [PMID: 18352014 DOI: 10.1103/physreve.77.021202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 01/11/2008] [Indexed: 05/26/2023]
Abstract
We propose to reconsider the diffusion of atoms in the Knudsen regime in terms of a complex dynamical reflection process. By means of molecular dynamics simulations, we emphasize the asymptotic nature of the cosine law of reflection at the atomic scale, and carefully analyze the resulting strong correlations in the reflection events. A dynamical interpretation of the accommodation coefficient associated with the slip at the wall interface is also proposed. Finally, we show that the first two moments of the stochastic process of reflection depend nonuniformly on the incident angle.
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Affiliation(s)
- Franck Celestini
- Laboratoire de Physique de la Matière Condensée, UMR 6622, CNRS and Université de Nice-Sophia Antipolis, Parc Valrose, Nice Cedex 2, France.
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Transmission probabilities and particle–wall contact for Knudsen diffusion in pores of variable diameter. Chem Eng Sci 2007. [DOI: 10.1016/j.ces.2007.08.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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