Detailed structural models for activated carbons from molecular simulation

Palmer, Jeremy C.; Brennan, John G.; Hurley, Margaret M.; Balboa, Alex; Gubbins, Keith E.

doi:10.1016/j.carbon.2009.06.037

Cited by 95 publications

(78 citation statements)

References 43 publications

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“…Nevertheless, despite moderate success, this method is unable to satisfactorily capture topological and morphological characteristics of the experimental sample. In contrast, it is well-demonstrated that realistic modeling of disordered porous materials is better achieved using the Hybrid Reverse Monte Carlo modeling (HRMC) technique, so that the final constructed model can reproduce many characteristic properties of the experimental sample including structural features, equilibrium gas adsorption and transport properties of the fluid in the target material [18,[25][26][27][28][29].…”

Section: ୀଵmentioning

confidence: 99%

Hybrid Reverse Monte Carlo simulation of amorphous carbon: Distinguishing between competing structures obtained using different modeling protocols

Farmahini

Bhatia

2015

Carbon

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Please cite this article as: Farmahini, A.H., Bhatia, S.K., Hybrid reverse monte carlo simulation of amorphous carbon: Distinguishing between competing structures obtained using different modelling protocols, Carbon (2014), doi: http://dx.doi.org/10.1016/j.carbon. 2014.11.013 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ABSTRACTWe explore different multi-stage and multi-constraint modelling strategies using the Hybrid Reverse Monte Carlo (HRMC) technique to develop realistic models for the amorphous structure of silicon carbide derived-carbon, and investigate the effect of modelling parameters on the development of nano-structural features of the constructed models. It is shown that application of long simulations with slow thermal quench rate is essential for modelling of amorphous structures. Nevertheless, very slow quenching rates are shown to lead to the formation of configurations with large fraction of sp 2 carbon, lacking the level of disorder required to match structure-related experimental data. The predicted gas adsorption isotherms are very sensitive to the pore size distribution (PSD), thus the final structure must reasonably reproduce the total pore volume and pore size distribution of the experimental sample. The frequently-observed strong first peak of the DFT-based PSD obtained from argon adsorption is shown to be an artifact of argon inaccessibility. Pore accessibility analysis of the constructed models, as well as MD simulations of gas transport demonstrate that the HRMC constructed structures contain short-range structural anisotropy, however the models are successful in capturing the long range internal energy barriers of amorphous carbon for methane.

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Section: ୀଵmentioning

confidence: 99%

Hybrid Reverse Monte Carlo simulation of amorphous carbon: Distinguishing between competing structures obtained using different modeling protocols

Farmahini

Bhatia

2015

Carbon

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“…22) was developed according the Monte Carlo modelling results [145][146][147] using the CharMM force field [148] and then its geometry was optimised using semiempirical PM6 quantum chemical method with the MOZIME algorithm [149].…”

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confidence: 99%

Cryogels: Morphological, structural and adsorption characterisation

Gun'ko

Savina

Mikhalovsky

2013

Advances in Colloid and Interface Science

281

205

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*Graphical Abstract (for review)Cryotripic gelation technique allows the synthesis of solid and soft macroporous gels Textural characterisation of cryogel in native superhydrated state with noninvasive methods Adsorption and diffusion characteristics of macroporous cryogels with respect to macromolecules and cells Theoretical modelling of adsorption from aqueous media *Highlights (for review) Please find the revised manuscript entitled "Cryogels: morphological, structural and adsorption characterisation" by Vladimir M. Gun'ko, Irina N. Savina, Sergey V. Mikhalovsky to re-consider for publication in the "Advances in Colloid and Interface Science"The paper was completely edited and changed according to reviewers comments.Sincerely yours, Prof. V. M. Gun'koCover Letter ABSTRACTExperimental results on polymer, protein, and composite cryogels and data treatment methods used for morphological, textural, structural, adsorption and diffusion characterisation of the materials are analysed and compared. Treatment of microscopic images with specific software gives quantitative structural information on both native cryogels and freeze-dried materials that is useful to analyse the drying effects on their structure. A combination of cryoporometry, relaxometry, thermoporometry, small angle X-ray scattering (SAXS), equilibrium and kinetic adsorption of low and high-molecular weight compounds, diffusion breakthrough of macromolecules within macroporous cryogel membranes, studying interactions of cells with cryogels provides a consistent and comprehensive picture of textural, structural and adsorption properties of a variety of cryogels. This analysis allows us to establish certain regularities in the cryogel properties related to narrow (diameter 0.4 < d < 2 nm), middle (2 < d < 50 nm) and broad (50 < d < 100 nm) nanopores, micropores (100 nm < d < 100 m) and macropores (d > 100 m) with boundary sizes within modified life science pore classification. Particular attention is paid to water bound in cryogels in native superhydrated or freeze-dried states. At least, five states of water -free unbound, weakly bound (changes in the Gibbs free energy G < 0.5-0.8 kJ/mol) and strongly bound (G > 0.8 kJ/mol), and weakly associated (chemical shift of the proton resonance  H = 1-2 ppm) and strongly associated ( H = 3-6 ppm) waters can be distinguished in hydrated cryogels using 1 H NMR, DSC, TSDC, TG and other methods. Different software for image treatment or developed to analyse the data obtained with the adsorption, diffusion, SAXS, cryoporometry and thermoporometry methods and based on regularisation algorithms is analysed and used for the quantitative morphological, structural and adsorption characterisation of individual and composite cryogels, including polymers filled with solid nano-or microparticles.

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“…A more rigorous approach that overcomes these limitations is provided by the so-called reconstruction methods, which use stochastic simulation techniques to obtain a realistic structural model of the adsorbent to which molecular simulations can be applied (Palmer et al 2009). On the other hand, by introducing information on the adsorbent pore size distribution, the lattice DFT model can be applied to a variety of adsorbent-adsorbate systems allowing to highlight those effects that are pore size dependent (Hocker et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Prediction of competitive adsorption on coal by a lattice DFT model

et al. 2009

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Adsorption is one of the main mechanisms involved in the ECBM process, a technology where CO 2 (or flue gas, i.e. a CO 2 /N 2 mixture) is injected into a deep coal bed, with the aim of storing CO 2 by simultaneously recovering CH 4 . A detailed understanding of the microscopic adsorption process is therefore needed, as the latter controls the displacement process. A lattice DFT model, previously extended to mixtures, has been applied to predict the competitive adsorption behavior of CO 2 , CH 4 and N 2 and of their mixtures in slit-shaped pores of 1.2 and 8 nm width. In particular, the effect of temperature, bulk composition and density on the resulting lattice pore profiles and on the lattice excess adsorption isotherms has been investigated. Important insights could be obtained; when approaching near critical conditions in the mesopores, a characteristic peak in the excess adsorption isotherm of CO 2 appears. The same effect could be observed neither for the other gases nor in the micropores. Moreover, in the case of mixtures, a depletion of the less adsorbed species close to the adsorbent surface is observed, which eventually results in negative lattice excess adsorption at high bulk densities.

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Detailed structural models for activated carbons from molecular simulation

Cited by 95 publications

References 43 publications

Hybrid Reverse Monte Carlo simulation of amorphous carbon: Distinguishing between competing structures obtained using different modeling protocols

Hybrid Reverse Monte Carlo simulation of amorphous carbon: Distinguishing between competing structures obtained using different modeling protocols

Cryogels: Morphological, structural and adsorption characterisation

Prediction of competitive adsorption on coal by a lattice DFT model

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