Sorption and Surface Area in Silica Aerogel

Kistler, S. S.; Fischer, Ernst; Freeman, I. R.

doi:10.1021/ja01250a034

Cited by 46 publications

(16 citation statements)

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“…Other reports of reversible sorption in the silica gel-water sys¬ tem are scarce indeed. Within recent years, however, Kistler, Fischer, and Freeman (19) have reported that their results indicate reversibi¬ lity of the desorption cycle. Although they obtained isothermal pres-✓ sure concentration diagrams showing considerable hysteresis, they be¬ lieve that if certain correction factors in connection with their ex¬ perimental arrangements were applied, the equilibrium values for p-c obtained during desorption would be within experimental error of those observed under conditions of increasing water concentration* More recently, Taylor (30) determined Isoteres for the water vaporsilica gel system.…”

Section: Table I Imentioning

confidence: 99%

The Effect of Heat-treatment on the SorptionDesorption Hysteresis Characteristics of Silica Gel.

Milligan¹,

Rachford²

1947

J. Phys. Chem.

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The characteristic hysteresis loop obtained from the isothermal sorption and desorption of vapors on porous substances was first observed in 1896 by van Bemmelen (2, 3) in his classical work on the silica-water system. The occurrence of sorption-desorption hysteresis has been referred to as the "van Bemmelen phenomenon" (18).Numerous investigators (6,8, 13, 14, 17) have verified the experimental existence of the sorption-desorption hysteresis phenomenon in many hydrous oxidewater systems, including silica gel. In contrast to the results of other investigators, Patrick (12) reported that a commercial silica gel gave no hysteresis loop when examined in a special apparatus in which elaborate precautions were taken to ensure the removal of inert gases. The sample of commercial silica gel was heated to 350°C. and was carried through several cycles of alternate evacuation and sorption of water vapor at 20°C. The isotherms obtained after this exhaustive treatment were reversible and showed no trace of a hysteresis loop.

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Section: Table I Imentioning

confidence: 99%

The Effect of Heat-treatment on the SorptionDesorption Hysteresis Characteristics of Silica Gel.

Milligan¹,

Rachford²

1947

J. Phys. Chem.

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“…He synthesized a silica-based aerogel via a wet chemical sol-gel process and subsequent supercritical solvent extraction [1,2]. The aerogel showed unique material properties such as high optical transparency or opacity, heat insulation capability, and high absorption capacity [3,4]. These properties led to the use of silica aerogels in ion exchange materials, adsorbents, semipermeable membranes, pharmaceuticals, cosmetics, optical and acoustical devices, coating materials, and heat insulation applications for buildings [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of a Calcium Carbonate Aerogel

Plank

Hoffmann

Schölkopf

et al. 2009

Advances in Materials Science and Engineering

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We report on a facile method for the preparation of a calcium carbonate aerogel consisting of aggregated secondary vaterite particles with an approximate average diameter of 50 nm. It was synthesized via a sol-gel process by reacting calcium oxide with carbon dioxide in methanol and subsequent supercritical drying of the alcogel with carbon dioxide. The resulting monolith was opaque, brittle and had overall dimensions of 6 × 2 × 1 cm. It was characterized by X-ray powder diffraction, nitrogen adsorption method (BET), and scanning electron microscopy.

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“…This method is valid in the cases of nonporous and macroporous adsorbents only. In the case of mesopo rous adsorbents, the methods based on works [34,35] and the method developed in full by Kiselev [36] are most widely used. According to [36], the adsorption film surface in mesopores can be given by the follow ing equation:…”

Section: Analysis Of the Main Methods Of Determining The Specific Surmentioning

confidence: 99%

Description of polymolecular adsorption on energetically heterogeneous surfaces

Петухова

Gur’yanov

2012

Prot Met Phys Chem Surf

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The Dubinin-Radushkevich equation is used for description of the first and subsequent adsorp tion layers in the case of polymolecular adsorption on energetically heterogeneous surfaces. It is found pos sible to predict adsorption isotherms of various vapors on nonporous and macroporous adsorbents on the basis of the minimal scope of experimental data. The derived two parameter equation of multilayer adsorp tion describes the adsorption equilibria in almost the whole range of mono and polymolecular adsorption, which is not complicated by capillary condensation, specific adsorption, or adsorption in micropores. When there are micropores and specific interactions between the adsorbate and the surface, the equation in the polymolecular range (beyond point B) enables one to characterize the surface and porosity of the adsorbent with respect to diverse adsorbates without information about standard adsorption isotherms, which makes the applicability field of the adsorption methods much broader and more valuable.

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Sorption and Surface Area in Silica Aerogel

Abstract: Tyndall beam which we use, but we have been able to determine its rate of coagulation with Mr.Green's condensation apparatus."Likewise, the electrification produced upon the disruption of materials and surfaces is well known.7

Cited by 46 publications

References 0 publications

The Effect of Heat-treatment on the SorptionDesorption Hysteresis Characteristics of Silica Gel.

The Effect of Heat-treatment on the SorptionDesorption Hysteresis Characteristics of Silica Gel.

Preparation and Characterization of a Calcium Carbonate Aerogel

Description of polymolecular adsorption on energetically heterogeneous surfaces

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