Scanning curves in wedge pore with the wide end closed: Effects of temperature

Klomkliang, Nikom; Duong, D.; Nicholson, D.

doi:10.1002/aic.14905

Cited by 7 publications

(3 citation statements)

References 39 publications

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“…DBdB approach provided a reasonably good description of simulated isotherms, which deteriorated as pore size decreases, which is expected for the macroscopic theory. For the isotherms predicted by DBdB we show the equilibrium desorption branch, however, it is unlikely that the experimental desorption branch would go along that path, as a system of necks connecting the pores typically lead to pore blocking or cavitation mechanisms of desorption 49,50 …”

Section: Resultsmentioning

confidence: 86%

Solvation pressure in spherical mesopores: Macroscopic theory and molecular simulations

2020

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Fluids adsorbing in nanoporous solids cause high solvation pressures that deform the solids and affect properties of the fluids themselves. We calculate solvation pressure of nitrogen adsorbed at 77.4 K in spherical silica mesopores using two methods: the macroscopic Derjaguin-Broekhoff-de Boer theory and molecular simulations. We show that both approaches give consistent results, and the observed pressures increase in smaller pores reaching the order of a hundred megapascals. The results are also typical for the solvation pressure in mesoporous materials, yet noticeably differ from the results for the cylindrical pore geometry. Furthermore, we show that the dependence of the solvation pressure at saturation on the reciprocal pore size is linear, and we use this relation for the calculation of the solid-liquid surface energy. The results can be employed for the prediction of the solvation pressure and the adsorption-induced deformation in the material with the spherical pore geometry.

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Section: Resultsmentioning

confidence: 86%

Solvation pressure in spherical mesopores: Macroscopic theory and molecular simulations

2020

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“…On the other hand, there has been some recent debate regarding the validity of the Kelvin equation down to the sub-10 nm level [22][23][24]. Thus, in the past two decades, researchers have examined alternative ways to describe this phenomenon, including the development of models that consider the thermodynamic energies throughout all phases using such techniques as density functional theory [1,15,25,26], grand canonical Monte Carlo simulation [27,28], and Molecular Dynamics [29,30].…”

Section: Introductionmentioning

confidence: 99%

A facile way of controlling capillary condensation: particle-based crystal

Jiao,

McCarthy

2024

Mater. Res. Express

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To demonstrate a facile method to control capillary condensation via the design of confined geometric structures, we use a particle self-assembly technique to fabricate porous materials with well-defined pore sizes. Four groups of silica particles were synthesized using the modified Stober method, and these groups of particles were then arranged in closely packed structures. Quantitative predictions of capillary condensation were made based on the Kelvin equation and an approximation of the geometric structures of our closely packed samples. Experimental observations revealed that water uptake at 100% relative humidity reached 40-50% relative to particle mass across sizes, closely aligning with theoretical predictions for small-particle systems, despite the fact that the geometry of some of the confined spaces corresponds to distances smaller than 10 nm. Despite deviation from theoretical predictions that are observed in larger particle systems, and which can be attributed primarily to practical limitations of attainable ordered structures at these scales, this fabrication method shows great potential for the creation of devices that allow facile control of capillary condensation in relevant applications such as vapor capture and humidity control.

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“…After completing the capillary condensation, the fluid in the pore is in the state of liquid-like with a higher density than the bulk system. To gain a better understanding regarding the pore texture inside the disordered materials, where the hysteresis loop is not symmetrical, the scanning curves [18][19][20] can alternatively be obtained by starting from any given point placed at the boundary of the hysteresis loop, and increasing or decreasing the pressures over another boundary. The sub-hysteresis loop could be obtained nested inside the main loop, in which a new pore domain is discovered.…”

Section: Introductionmentioning

confidence: 99%

Unveiling the Molecular Origin of Vapor-Liquid Phase Transition of Bulk and Confined Fluids

et al. 2022

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At temperatures below the critical temperature, discontinuities in the isotherms are one critical issue in the design and construction of separation units, affecting the level of confidence for a prediction of vapor–liquid equilibriums and phase transitions. In this work, we study the molecular mechanisms of fluids that involve the vapor–liquid phase transition in bulk and confinement, utilizing grand canonical (GCE) and meso-canonical (MCE) ensembles of the Monte Carlo simulation. Different geometries of the mesopores, including slit, cylindrical, and spherical, were studied. During phase transitions, condensation/evaporation hysteretic isotherms can be detected by GCE simulation, whereas employing MCE simulation allows us to investigate van der Waals (vdW) loop with a vapor spinodal point, intermediate states, and a liquid spinodal point in the isotherms. Depending on the system, the size of the simulation box, and the MCE method, we are able to identify three distinct groups of vdW-type isotherms for the first time: (1) a smooth S-shaped loop, (2) a stepwise S-shaped loop, and (3) a stepwise S-shaped loop with just a vertical segment. The first isotherm type is noticed in the bulk and pores having small box sizes, in which vapor and liquid phases are close and not clearly identified. The second and the third types occurred in the bulk, cylindrical, and slit mesopores with sufficiently large spaces, where vapor and liquid phases are distinctly separated. Results from our studies provide an insight analysis into vapor–liquid phase transitions, elucidating the effect of the confinement of fluid behaviors in a visual manner.

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Scanning curves in wedge pore with the wide end closed: Effects of temperature

Cited by 7 publications

References 39 publications

Solvation pressure in spherical mesopores: Macroscopic theory and molecular simulations

Solvation pressure in spherical mesopores: Macroscopic theory and molecular simulations

A facile way of controlling capillary condensation: particle-based crystal

Unveiling the Molecular Origin of Vapor-Liquid Phase Transition of Bulk and Confined Fluids

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