Investigation of surface properties of lunar regolith: Part I

Robens, E.; Bischoff, A.; Schreiber, Andreas; Dąbrowski, A.; Unger, K. K.

doi:10.1016/j.apsusc.2006.12.098

Cited by 34 publications

(25 citation statements)

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“…A number of systems were examined to check the proposed method for calculating the H3 hysteresis loop in the low pressure region: the adsorption of water at T = 298 K on a lunar soil sample [2], adsorption of water at T = 293 K on shungite [4] and kaolinite [3,7], and the adsorption of pyridine at T = 323 K on montmorillonite [5,6]. The corresponding adsorption-desorption isotherms are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…According to the commonly accepted theory of adsorption hysteresis, the abscissa of the extreme left-hand point of the hysteresis loop corresponds to relative pressure of the adsorbate in the bulk phase not less than p/p s » 0.4-0.5 [1]. On the other hand, considerable experimental work has shown that the H3 hysteresis loop continues into the low pressure region and often does not close even as p/p s ® 0 [2][3][4][5][6][7][8]. In 1957, Arnell and McDermot [9] proposed that hysteresis at low pressures should be attributed to the formation of traps in the adsorbent upon adsorption.…”

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Adsorption hysteresis at low relative pressures

et al. 2011

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A qualitative and quantitative description is given for the H3 hysteresis loop at low pressures using the generalized Dubinin-Astakhov equation. Irreversibility of the adsorption system was taken into account by introducing an additional governing parameter. A relationship was found between this parameter and the potential barrier for desorption from adsorption traps. The proposed equation satisfactorily describes the hysteresis loop at low pressures for a series of systems.Among all the types of hysteresis loops classified by De Boer and IUPAC [1], greatest interest is found for H3 loops, which are characteristic for adsorption on surfaces with planar parallel slits. A distinguishing feature of H3 hysteresis loops is that they often continue into the low pressure region. According to the commonly accepted theory of adsorption hysteresis, the abscissa of the extreme left-hand point of the hysteresis loop corresponds to relative pressure of the adsorbate in the bulk phase not less than p/p s » 0.4-0.5 [1]. On the other hand, considerable experimental work has shown that the H3 hysteresis loop continues into the low pressure region and often does not close even as p/p s ® 0 [2][3][4][5][6][7][8]. In 1957, Arnell and McDermot [9] proposed that hysteresis at low pressures should be attributed to the formation of traps in the adsorbent upon adsorption. When adsorbate molecules fall into these traps, they either desorb very slowly or do not desorb at all. There are two types of traps in an adsorbent: 1) diffusion traps and 2) chemical traps. Diffusion traps arise when access opens upon adsorption deformation of the adsorbent to a plane previously inaccessible to the adsorbate molecules. Desorption leads to a change in the structure of the adsorbent itself due to irreversible changes in its lattice, which markedly hinders diffusion of the adsorbate from the adsorbent cavities into the surrounding environment. Chemical traps arise as a consequence of the formation of bonds between polar adsorbate molecules and exchange cations of the adsorbent. A characteristic example is the formation of chemical traps in laminar silicates [3]. The formation of the two types of traps leads to a situation, in which the desorption potential barrier increases relative to the adsorption potential barrier.The nature of adsorption hysteresis in the region of low pressures appears rather well understood in general terms. On the other hand, there is no well-founded method for calculating the H3 hysteresis loop in the low pressure region.

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Adsorption hysteresis at low relative pressures

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“…As examples, we consider: 1) the adsorption of nitrogen (T = 78 K) on coal samples ZC6 [9]; 2) the adsorption of nitrogen (T = 78 K) on Davisil F silica [10]; 3) adsorption of water (Т = 293 K) on lunar soil sample [11] [12]; 4) adsorption of water (Т = 293 K) on rice starch [13]. Further information to the samples and measurements are described in [9] Now we have to study the adsorption of nitrogen on coal sample ZC6 ( Figure 1).…”

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confidence: 99%

Fractal Characteristics of Microporous Adsorbents

Кутаров¹,

Schieferstein²,

Zub³

et al. 2017

MSA

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The traditional version of the theory of volume filling of micropores was used for the estimation of the fractal dimension of microporous solids. For this purpose, the Dubinin's integral equation was solved for infinite and limited integration limits. The results were applied to the adsorption of nitrogen (T = 78 K) on coal samples and Davisil F silica and to the adsorption of water (Т = 293 К) on lunar soil sample and on rice starch.

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“…Some adsorption measurements of various gases at lunar regolith fine-grained sand (∅ < 100 µm) published elsewhere (Robens et al 2007(Robens et al , 2008 were evaluated using the BET II equation (1) and the Expanded Pickett equation (EP) (6) or (9). The evaluated isotherms are shown in Figs.…”

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The Pickett equation analytical continuation

Кутаров

Robens

2011

Adsorption

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Usually gas adsorption isotherms are evaluated by means of the classic two-parameter equation of Brunauer, Emmett and Teller (BET II). This equation however fails when multilayer adsorption or capillary condensation occurs. The present work suggests the use of the threeparameter Pickett equation in the range of high adsorptive pressure of the gaseous phase. An analytical continuation of the Pickett equation allows for the description of the whole isotherm. Adsorption isotherms of krypton, water vapor, and n-heptane at Lunar regolith samples are evaluated using both, BET II and continued Pickett equation.

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Investigation of surface properties of lunar regolith: Part I

Cited by 34 publications

References 10 publications

Adsorption hysteresis at low relative pressures

Adsorption hysteresis at low relative pressures

Fractal Characteristics of Microporous Adsorbents

The Pickett equation analytical continuation

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