Estimation of reference state parameters for sorption modeling of gaseous substances

Milewska-Duda, Janina; Duda, Jerzy; Jodłowski, G. S.; Wójcik, M.

doi:10.1016/s0927-7757(02)00157-7

Cited by 3 publications

(7 citation statements)

References 8 publications

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“…For accurate modeling of sorption based on thermodynamic analysis, exact values are necessary of both cohesion energy and the molecule volume of gaseous sorbates. The state equation of gases for the model is developed and introduced to the computation packet (Milewska-Duda et al 2002). …”

Section: Numerical Analysismentioning

confidence: 99%

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Sorption of CO2 in lignites from Polish coal mines: measurements and thermodynamic analysis

Baran

Jodłowski

Zarębska³

2016

Adsorption

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The purpose of the work presented in this paper was to adapt the Multiple Sorption Model (MSM), originally developed for hard coals, to study sorption in lignites. It also includes an analysis of the sorption process of small molecule compounds in lignites. Measurements were made of the sorption isotherms of carbon dioxide in two samples of lignite from Polish collieries at different temperatures (298, 313 and 323 K) and in the pressure range up to 5 MPa. Subsequently, simulations of the isotherms for selected carbon dioxide-lignite systems were performed using the MSM. They were evaluated using the empirical isotherms until agreement of the isotherms was attained and the parameters of the sorption system reached reasonable values. Surprisingly, a low contribution of absorption was found in the overall sorption process probably as an effect of the high porosity of the sample and the presence of a large number of high-energy sites on the coal surface. Sorbate molecules occupied these high-energy sites on the surface and did not migrate to the absorption subsystem.

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Section: Numerical Analysismentioning

confidence: 99%

“…Feature of the model is to use the number of moles to simulate sorption isotherms. The volume of gas is converted to the number of moles using the original equation of state incorporated into the model (Milewska-Duda et al 2002). Therefore sorption in Figs.…”

Section: Numerical Analysismentioning

confidence: 99%

Sorption of CO2 in lignites from Polish coal mines: measurements and thermodynamic analysis

Baran

Jodłowski

Zarębska³

2016

Adsorption

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“…In the case of small nearly spherical adsorbate molecules the formulas for Δ H and Δ S can be relatively easily derived by using a generalized BET approach. ,− We consider creation of adsorbate clusters in highly dispersed space limited by a geometry of pores. The clusters are constructed by adding consecutive layers being in equilibrium with the volatile phase.…”

Section: Generalized Bet-like Adsorptiontheoretical Basis and Unibet...mentioning

confidence: 99%

“…Despite serious simplifications and restrictions inherent in the above assumptions (see refs and ), they enable us to get a more realistic description of adsorption in microporous materials than the original BET theory, making it possible to express explicitly effects of pore geometry on the process. In particular, the assumptions 1−3 allow us to consider not only stacklike clusters (as assumed in BET theory), but also branched ones; see Figure .…”

Section: Generalized Bet-like Adsorptiontheoretical Basis and Unibet...mentioning

confidence: 99%

“…This paper presents an attempt to build the models satisfying the above demands. It follows the line of our earlier papers, − where the BET theory 4 was generalized and adapted to take into account specific properties of microporous adsorbents of irregular structure (LBET approach). In a recent paper 13 a general mathematical model for constrained multilayer adsorption is derived and next simplified to the analytical form applicable for energetically homogeneous microporous surfaces ( LcBET formula).…”

Section: Introductionmentioning

confidence: 99%

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Modeling of Surface Heterogeneity of Microporous Adsorbents with LBET Approach

Duda

Milewska-Duda

2005

Langmuir

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A package of new isotherm equations aimed at examination of pore structure of sub- and microporous materials with respect to a surface heterogeneity is proposed. One considers adsorption of small nearly spherical molecules in irregular pores of molecular size. A generalized BET theory is exploited together with a thermodynamic description of the process and handling restrictions for multilayer adsorption (LBET approach). Realistic multivariant relationships linking a surface energy distribution with the pore size are proposed, and exponential distribution of the pore size is accepted. As a result, the heterogeneous adsorption equations (uLBET formulas) are derived, dedicated for irregular microporous systems. It was shown that they may be well-approximated with analytical BET-like formulas (the models of the LBET-type), enabling fast multivariant examination of real microporous materials. Such an examination provides complementary information on adsorption mechanisms, thus, allowing more reliable evaluation of the system parameters. Results of the new model's application to an empirical system (nitrogen adsorption on an activated carbon) are shown.

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Identification of hard coal surface structure using polar and apolar small molecule substances

2016

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The paper presents a numerical approach to the analysis of the statistical effect of functional groups on the sorption of methanol and water on hard coal samples. The material used for the analysis was obtained from numerous samples of hard subbituminous and bituminous coals up to anthracite from different Polish coal mines and includes sorption isotherms of water and methanol vapors, as well as carbon dioxide and methane on these samples. Measurements were made of the sorption isotherms of water and methanol vapors and the data set has been supplemented with the sorption isotherms of water, methane and carbon dioxide taken from the literature for the precise estimation of the model parameters. More precise estimation is reached by using a strong setting of the coal structure parameters for a bigger number of sorption system, and in each case the same parameters of coal geometry are constant with an exact fitting of sorption isotherm. The adsorption-absorption model of the sorption in coal (Multiple Sorption Model-MSM) is used in the numerical experiments and the parameters of hard coal structure and the sorption systems are estimated. It has been stated that water as a polar substance together with methanol, as well as carbon dioxide and methane give good estimates of coal structure and let us quantify the polar effect of surface groups present in hard coal. The polar effect is introduced in the model in the range of adsorption and expansion subprocesses. The presence of oxygen groups in the bulk of coal matter has no significant effect and can be neglected. A weak decreasing tendency of polar factors ratio for water and methanol is discovered.

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Estimation of reference state parameters for sorption modeling of gaseous substances

Cited by 3 publications

References 8 publications

Sorption of CO2 in lignites from Polish coal mines: measurements and thermodynamic analysis

Sorption of CO2 in lignites from Polish coal mines: measurements and thermodynamic analysis

Modeling of Surface Heterogeneity of Microporous Adsorbents with LBET Approach

Identification of hard coal surface structure using polar and apolar small molecule substances

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