Application of the Dubinin-Radushkevich and Dubinin-Astakhov equations in the characterization of microporous solids

Gil, A.; Grange, Paul

doi:10.1016/0927-7757(96)81455-5

Cited by 124 publications

(82 citation statements)

References 44 publications

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“…While several studies [13,14] postulated that the Dubinin-Radushkevich equation applies only to solids with a uniform structure of micropores, others [15][16][17][18][19] proposed a modification of this equation when a microporous solid possesses micropores of the same shape but of different sizes. One of those modifications is the Dubinin-Astakhov equation, which can be applied to the description of the adsorption onto structurally heterogeneous solids [8,20]. In this work the Dubinin-Astakhov method has been used because of the heterogeneous structure of the samples and the better correlation coefficient obtained in all cases.…”

Section: Influence Of Activation Conditionsmentioning

confidence: 99%

“…The N 2 adsorption-desorption isotherms were obtained in the 10 À5 -1.0 P/P 0 range, although the P/P 0 range used to calculated the BET surface area (S BET ) was 0.05-0.3 [7]. The t-method was used for the micropore volume and BJH was uses to obtain the mean mesopore size, whereas DubininAstakhov (DA) model was applied to the CO 2 isotherms to determine the DA surface area (S DA ), micropore volume and mean micropore size [8]. The Non-Local Density Functional Theory (NLDFT) with pore geometry slit was used to calculate the pore size distribution from both the CO 2 and N 2 isotherms [9].…”

Section: Samples Characterizationmentioning

confidence: 99%

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Development of porosity upon physical activation of grape seeds char by gas phase oxygen chemisorption–desorption cycles

Jiménez-Cordero

Heras

Alonso-Morales

et al. 2013

Chemical Engineering Journal

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h i g h l i g h t sNovel method of activation by cycles permits good control of porosity development. S BET values above 1000 m 2 /g can be obtained with burn-off values lower than 40%. The low burn-off helps to maintain granular morphology of the activated carbons.Carbons with unique hollow core structure and wall thickness of 250 lm are produced.The activated carbons showed a good mechanical strength during attrition test. a r t i c l e i n f o t r a c tActivation of grape seeds char upon cyclic oxygen chemisorption-desorption permits a controlled development of porosity versus burn-off using air as a cheap activation agent. In this work the influence of chemisorption and desorption temperature and the number of cycles is investigated. A fast increase of BET surface area (S BET ) is obtained in the two first cycles; that increase becomes then lower although the S BET continues increasing upon the successive cycles. Regarding the Dubinin-Astakhov surface area (S DA ) a slow increase was observed from cycle to cycle. The activation process led to the development of both micro and mesoporosity. Under the optimum conditions for surface area development, i.e. an oxidation temperature of 275°C and desorption temperatures between 850 and 950°C, values of 1129-1256 and 1339-1219 m 2 /g were obtained for S BET and S DA , respectively. Porosity was found to increase mainly during the desorption stage, although chemisorption also led to some surface area development. SEM characterization showed that the activated carbon maintained the granular morphology of the seeds even after 10 cycles showing the egg-shell structure of the precursor with longer and deeper cracks at the outer surface. The activated carbons showed a good mechanical strength during attrition tests.

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Section: Influence Of Activation Conditionsmentioning

confidence: 99%

Section: Samples Characterizationmentioning

confidence: 99%

Development of porosity upon physical activation of grape seeds char by gas phase oxygen chemisorption–desorption cycles

Jiménez-Cordero

Heras

Alonso-Morales

et al. 2013

Chemical Engineering Journal

View full text Add to dashboard Cite

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“…Equation (9) is based on the assumption that an adsorbent possesses micropores of the same shape but different sizes. The concentration of a micropore group can be calculated from Equation (Gil and Grange 1996):…”

Section: Characterisation Of Pore Structurementioning

confidence: 99%

“…Such pore size distribution is (Bansal and Goyal 2005). A modified Dubinin-Astahov equation (D-A) was used to describe IPA vapour adsorption on structurally heterogeneous adsorbents (Gil and Grange 1996):…”

Section: Characterisation Of Pore Structurementioning

confidence: 99%

Adsorption characteristics of propan-2-ol vapours on activated carbon Sorbonorit 4 in electrothermal temperature swing adsorption process

Downarowicz

2015

Adsorption

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Adsorption characteristics of propan-2-ol on Sorbonorit 4 activated carbon were determined using the breakthrough curve tests in a cyclic electrothermal temperature swing adsorption process. Maximum adsorption capacity, breakthrough time, throughput ratio and length of unused bed were also evaluated. As a result of multiple regeneration, the adsorption capacity of Sorbonorit 4 increased. Electrothermally-induced changes in the internal structure of Sorbonorit 4 and in the chemical composition of its surface were assessed based on adsorption equilibrium measurements by the gravimetric method and X-ray photoelectron spectroscopy (XPS). Three samples of virgin, direct resistively heated and electrothermally regenerated Sorbonorit 4 were used. The structural characteristics of activated carbon show that that fresh and direct resistive heated Sorbonorit 4 has a bimodal structure. Regenerated activated carbon contains one fraction of micropores. XPS analysis revealed that the same hydroxyl, carbonyl and carboxyl groups were found on the surface of all Sorbonorit 4 samples, albeit in different volume ratios. Regenerated Sorbonorit 4 has higher adsorption capacity than pure adsorbent while resistively heated Sorbonorit 4 displays lower adsorption efficiency.

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“…4 The CO 2 adsorption test results obtained may be used to get further information about the material that is studied, as the physical adsorption of gases and vapors is a very useful technique for the characterization of microporous solids. 17 For many years, since the surface area was presumed to be the measure of adsorption capacity, microporous solids such as activated carbons have been characterized using the B.E.T. method applied to the adsorption isotherm.…”

Section: Introductionmentioning

confidence: 99%

CO$_{2}$ adsorption behavior and kinetics on chemically modified activated carbons

Çağlayan¹,

Aksoylu²

2016

Turk J Chem

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CO 2 adsorption capacities of activated carbon-based adsorbents subjected to different treatments, such as HNO 3 oxidation, air oxidation, alkali impregnation, and heat treatment under helium gas atmosphere, were determined by gravimetric analyses and reported previously by our group. In the current work, the experimental adsorption isotherms of these modified activated carbon samples were fitted to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models. The best fits were obtained to the D-R equation, indicating competitive or multilayer CO 2 adsorption occurring in the micropores of the adsorbents. Air oxidation followed by alkali impregnation led to the highest micropore volume, ranging between 0.259 and 0.298 g.CO 2 /g.adsorbent, which resulted in the highest CO 2 adsorption capacity of 8.87%at 1 atm and 25• C. The CO 2 adsorption kinetic plots revealed a two-step adsorption process for all the adsorbents: a relatively fast kinetic region phase followed by a slow one until reaching the equilibrium. Pseudo-first and pseudo-second order kinetics explain adsorption for the kinetic region for most of the samples. When the whole adsorption data range is considered, the adsorption cannot be explained by any model at 25• C due to the complex nature of the adsorbents, but the adsorption behavior fits rather well to pseudo-first order kinetics at 120• C for the alkali-impregnated samples.

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Application of the Dubinin-Radushkevich and Dubinin-Astakhov equations in the characterization of microporous solids

Cited by 124 publications

References 44 publications

Development of porosity upon physical activation of grape seeds char by gas phase oxygen chemisorption–desorption cycles

Development of porosity upon physical activation of grape seeds char by gas phase oxygen chemisorption–desorption cycles

Adsorption characteristics of propan-2-ol vapours on activated carbon Sorbonorit 4 in electrothermal temperature swing adsorption process

CO$_{2}$ adsorption behavior and kinetics on chemically modified activated carbons

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