A study of the mechanism of micropore fillingII. Pore filling of a microporous silica

Ambient pressure silica aerogel thin films have recently been prepared by exploiting reversible drying shrinkage caused by derivatization of the internal gel surface. Aerogels have porosities of upto 99.9% and due to the small size of the pores (few nanometers), large capillary stresses are produced in gels that are partially saturated with a wetting liquid. As a result of these capillary stresses, the flexible silica network undergoes strain which has been observed using environmental microscopy. This technique allows variation of the equilibrium vapor pressure and temperature, and a simultaneous monitoring of the deformation of the unconstrained film thickness. We have observed >600% deformation during the pore-filling and pore-emptying cycles. In this presentation, we discuss the unique stress-strain behavior of these films.Ref.: Sai S. Prakash, C. Jeffrey Brinker, Alan J. Hurd & Sudeep M. Rao, "Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage", Nature. Vol. 374, 30 March, 1995, 439-443.

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Characterization of Metal-Doped Methylated Microporous Silica for Molecular Separations

International Journal of Membrane Science and Technology ◽

10.15379/2410-1869.2015.02.02.09 ◽

2016 ◽

Vol 2 (2) ◽

pp. 85-100

Author(s):

Tània Gumí ◽

Hany El-Feky ◽

Kelly Briceño ◽

Kamila Szałata ◽

Miguel Hevia

Keyword(s):

Microporous Silica ◽

Molecular Separations ◽

Metal Doped

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Gas Porosimetry by Gas Adsorption as an Efficient Tool for the Assessment of the Shaping Effect in Commercial Zeolites

Nanomaterials ◽

10.3390/nano11051205 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1205

Author(s):

Alejandro Orsikowsky-Sanchez ◽

Christine Franke ◽

Alexander Sachse ◽

Eric Ferrage ◽

Sabine Petit ◽

...

Keyword(s):

Ir Spectroscopy ◽

Strong Interaction ◽

Gas Adsorption ◽

Co2 Adsorption ◽

Adsorption Properties ◽

Preparation Process ◽

Pore Filling ◽

Irreversible Adsorption ◽

Efficient Tool ◽

4A Zeolite

A set of three commercial zeolites (13X, 5A, and 4A) of two distinct shapes have been characterized: (i) pure zeolite powders and (ii) extruded spherical beads composed of pure zeolite powders and an unknown amount of binder used during their preparation process. The coupling of gas porosimetry experiments using argon at 87 K and CO2 at 273 K allowed determining both the amount of the binder and its effect on adsorption properties. It was evidenced that the beads contain approximately 25 wt% of binder. Moreover, from CO2 adsorption experiments at 273 K, it could be inferred that the binder present in both 13X and 5A zeolites does not interact with the probe molecule. However, for the 4A zeolite, pore filling pressures were shifted and strong interaction with CO2 was observed leading to irreversible adsorption of the probe. These results have been compared to XRD, IR spectroscopy, and ICP-AES analysis. The effect of the binder in shaped zeolite bodies can thus have a crucial impact on applications in adsorption and catalysis.

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Sorption of phenols on hexadecyltrimethylammonium- modified bentonite: Application of Polanyi−Manes potential theory

Energy & Environment ◽

10.1177/0958305x20977286 ◽

2020 ◽

pp. 0958305X2097728

Author(s):

Jiyeon Choi ◽

Dong-Ik Slong ◽

Won Sik Shin

Keyword(s):

Molar Volume ◽

Potential Theory ◽

Characteristic Curve ◽

Chemical Compositions ◽

Pore Filling ◽

Sorption Data ◽

Similar Chemical ◽

Competitive Model ◽

Sorption Potential ◽

Sorption Systems

This study investigated the sorption of phenol and 4-chlorophenol (4-CP) on natural bentonite modified with hexadecyltrimethylammonium (HDTMA) cation. The Freundlich, Langmuir, Dubinin−Radushkevich (DR), Sips, and Polanyi−Dubinin−Manes (PDM) models fitted the sorption data well (R2 > 0.92). The Freundlich coefficient and the maximum sorbed amount of the Langmuir and PDM models of 4-CP were higher than phenol because of higher hydrophobicity (log Kow = 2.39 for 4-CP and 1.46 for phenol). The PDM model that includes solubility and molar volume was highly useful in predicting the sorption of phenols having widely different hydrophobicity and solubility. The characteristic curves, the plot of sorbed volume ( qv) versus the sorption potential per molar volume ( ε/ Vm) of 4-CP and phenol were distinctly different although they have similar chemical compositions. The selectivity of 4-CP (3.72) was higher than that of phenol (0.27) in binary sorption systems. The sorbed volume ( qv) in the binary sorption was remarkably reduced and the characteristic curve had wider distribution owing to competition in pore-filling. The sorption behaviors were elucidated by partitioning and pore-filling mechanisms. Among the tested binary sorption models, the modified Langmuir competitive model was the best in the prediction of the binary sorption (R2 > 0.98).

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