Water vapor adsorption on chars and active carbons–oxygen sensors prepared from a tropical tree wood

Vartapetyan, R. Sh.; Волощук, А. М.; Buryak, А. К.; Artamonova, C.D.; Belford, R. Linn; Ceroke, P.J.; Kholine, D.V.; Clarkson, R. B.; Odintsov, B. M.

doi:10.1016/j.carbon.2005.03.028

Cited by 19 publications

(11 citation statements)

References 19 publications

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“…(c) The relative pressure at which pore filling occurs was lower for the models with functional groups and was below the saturation pressure for models with functional groups. This finding was consistent with what has been observed in experiments. − This is due to the greater interaction energy between water molecules and functional groups, and that leads to favorable nucleation of water clusters. (d) The hysteresis loop was smaller for models with functional groups as opposed to pristine models.…”

Section: Introductionsupporting

confidence: 91%

Computational Study of the Effect of Functional Groups on Water Adsorption in Mesoporous Carbons: Implications for Gas Adsorption

Peng

Vicent-Luna

Jain

et al. 2019

ACS Appl. Nano Mater.

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The adsorption and diffusion of water in realistic CMK-1, CMK-3, and CMK-5 carbon models at 300 K has been studied via grand canonical Monte Carlo and molecular dynamics simulations. The presence of −COOH and −OH functional groups has been found to be crucial to describe the adsorption process, while the models without functional groups are unable to capture the host−guest interactions. Functional groups were attached in cylindrical shells on the outer walls of CMK models in 2 and 4 cylindrical shells to study the effect of their concentration and location on water adsorption. The adsorption isotherm starts at a lower chemical potential, with water adsorbed near functional groups forming small clusters. On increasing chemical potential the water cluster grows and merges to form bigger clusters and completely fills the pores. We also analyzed the isosteric heat, radial distribution functions, hydrogen bond, and cluster size of water molecules. It indicates that the adsorption occurs due to the formation and growth of water clusters. For CMK-1, CMK-3, and CMK-5 models with functional groups, the pore filling happens at lower chemical potential, when compared to the models without functional groups, owing to the presence of active sites which favors the nucleation of water molecules. The effect of functional groups is also remarkable in the diffusion of water inside the pores of CMK-1, CMK-3, and CMK-5 models, lowering the mobility of the adsorbed molecules. The agreement between the results of the models with functional groups and the experimental observations makes the presence of these groups necessary to study the adsorption and diffusion of water in CMK-1, CMK-3, and CMK-5 carbon models.

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Section: Introductionsupporting

confidence: 91%

Computational Study of the Effect of Functional Groups on Water Adsorption in Mesoporous Carbons: Implications for Gas Adsorption

Peng

Vicent-Luna

Jain

et al. 2019

ACS Appl. Nano Mater.

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“…One is the point charge models such as SPC, SPC/E, and ST2 models, while the other is the square-well site models such as the primitive model (PM) − and the Muller and co-workers 5,6 models. The simulated adsorption isotherms of water on activated carbon show a distinctly vertical pore filling, while experimental studies − show a slight adsorption at low relative pressures ( P / P 0 , where P 0 is the saturation pressure), a steep increasing (but not vertical) of adsorption isotherm at moderate P / P 0 , and a saturation at high P / P 0 . The common reason used to explain the difference between the simulation results and the experimental studies is that porous carbon contains functional groups; however, other factors such as pore width and length could also contribute to this difference.…”

Section: Introductionmentioning

confidence: 85%

Adsorption of Water in Finite Length Carbon Slit Pore: Comparison between Computer Simulation and Experiment

Wongkoblap

Duong

2007

J. Phys. Chem. B

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The effects of surface dimensions and topology on the adsorption of water on a graphite surface at 298 K were investigated using the grand canonical Monte Carlo (GCMC) simulation. Regarding the surface topology, we specifically considered the functional group and its position on the surface. The hydroxyl group (OH) is used as a model for the functional group. For describing the interaction of water, we used the potential model proposed by Muller et al., and the simulated isotherms of water in slit pores are found to depend on the position and concentration of the functional group. The onset of adsorption shifts to lower pressure when the concentration of functional group increases or when the functional group is positioned at the center of the graphene surface. The configuration of a group of functional groups also affects the adsorption isotherm. In all cases investigated, we have found that the hysteresis loop always exists, and the loop size depends on the concentration of the functional group and its position. Finally, we tested the molecular model of water adsorption on a functional graphite pore against the experimental data of a commercial activated carbon. The agreement is found to be satisfactory when the model porous solid is composed of pores having width in the range between 10 and 20 A and functional groups positioned at the center of the graphitic wall.

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“…The 2-D effects would be better classified by criterion 2 above. Since evidence exists suggesting the physical properties of the adsorbed phase of such molecules in micropores are better described by solid-phase than liquid phase [35][36][37] , the apparent excluded volume may also be due to an incorrect density attributed to the adsorbed phase. The Gurvitsch volumes for CO2, iso-butane, and SF6 were not reported due to experimental equipment limitations.…”

Section: -Molecular Packing Effects Dictated By Long-range Structurementioning

confidence: 99%

Decoding gas-solid interaction effects on adsorption isotherm shape: I. Non-polar adsorptives

Madani

Kwong

Rodríguez‐Reinoso

et al. 2018

Microporous and Mesoporous Materials

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A suite of non-polar adsorptives of different kinetic diameters and shape were used to determine adsorption and pore filling mechanism of a well-characterised poly(furfuryl alcohol)-based activated carbon. Triplicate measured Type I adsorption isotherms for each adsorptive were averaged to provide standard deviation in relative pressures and associated amounts adsorbed. Plateau amounts adsorbed for N2, Ar, CH4, and C6H6, provided Gurvitsch volumes averaged to 0.368 ± 0.015 cm 3 (liq)/g. The calculated Gurvitsch volumes were compared with those derived via the Dubinin-Radushkevich (DR) equation. Additional adsorptives were CO2, iso-butane and SF6. The results of these 7 adsorptives were used to qualitatively analyse and decode a micropore filling adsorption mechanism. The DR equation was also used for further analysis of the pore filling mechanism. Based on the adsorbate-adsorbate and adsorbate-adsorbent interactions, adsorbates were classified into three groups: (a) Non-polar with nonspecific interactions (no dipole, no quadrupole, not readily polarizable: Ar, N2, CH4 and iso-butane), adsorbing as a continuous uptake over the observed relative pressure range; (b) Non-polar adsorptives with potential for specific interactions (no dipole, quadrupole moment: CO2 and C6H6), adsorbing as a condensation process over a relatively narrow relative pressure range in a medium pressure range; (c) Halogenated adsorptives (no dipole, no quadrupole, polarizable: SF6), adsorbing with an S-shaped uptake extending over a relatively broad relative pressure range.

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Water vapor adsorption on chars and active carbons–oxygen sensors prepared from a tropical tree wood

Cited by 19 publications

References 19 publications

Computational Study of the Effect of Functional Groups on Water Adsorption in Mesoporous Carbons: Implications for Gas Adsorption

Computational Study of the Effect of Functional Groups on Water Adsorption in Mesoporous Carbons: Implications for Gas Adsorption

Adsorption of Water in Finite Length Carbon Slit Pore: Comparison between Computer Simulation and Experiment

Decoding gas-solid interaction effects on adsorption isotherm shape: I. Non-polar adsorptives

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