Modeling of type IV and V sigmoidal adsorption isotherms

Buttersack, Christoph

doi:10.1039/c8cp07751g

Cited by 150 publications

(87 citation statements)

References 76 publications

(123 reference statements)

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“…6). This relationship is consistent with the type V isotherm model, which indicates the presence of capillary condensation 51 . This is commonly found in porous media, where a vapour condenses at a pressure below its saturated vapour pressure [52][53][54] .…”

Section: Resultssupporting

confidence: 89%

Graphene oxide integrated silicon photonics for detection of vapour phase volatile organic compounds

Tsui

Mao

Alodhayb

et al. 2020

Sci Rep

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the optical response of a graphene oxide integrated silicon micro-ring resonator (GoMRR) to a range of vapour phase Volatile organic compounds (Vocs) is reported. the response of the GoMRR to all but one (hexane) of the VOCs tested is significantly higher than that of the uncoated (control) silicon MRR, for the same vapour flow rate. An iterative Finite Difference Eigenmode (FDE) simulation reveals that the sensitivity of the GO integrated device (in terms of RIU/nm) is enhanced by a factor of ~2, which is coupled with a lower limit of detection. critically, the simulations reveal that the strength of the optical response is determined by molecular specific changes in the local refractive index probed by the evanescent field of the guided optical mode in the device. Analytical modelling of the experimental data, based on Hill-Langmuir adsorption characteristics, suggests that these changes in the local refractive index are determined by the degree of molecular cooperativity, which is enhanced for molecules with a polarity that is high, relative to their kinetic diameter. We believe this reflects a molecular dependent capillary condensation within the graphene oxide interlayers, which, when combined with highly sensitive optical detection, provides a potential route for discriminating between different vapour phase VOCs.

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Section: Resultssupporting

confidence: 89%

Graphene oxide integrated silicon photonics for detection of vapour phase volatile organic compounds

Tsui

Mao

Alodhayb

et al. 2020

Sci Rep

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“…Therefore, the adsorption of VOCs slowly increases and tends to become constant. The Dubinin-Radushkevich (D-R) equation ( 30 ) was adopted to fit the corresponding isotherms; as shown, the two isotherms fit the D-R equation well (fit parameters are given in table S2).…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the adsorption of VOCs slowly increases and tends to become constant. The Dubinin-Radushkevich (D-R) equation (30) was adopted to fit the corresponding isotherms; as shown, the We measured t dynamic adsorption breakthrough curves of the HNM loaded with toluene and acetone at 200 ppmv, using the experimental apparatus shown in Fig. 6A.…”

Section: Voc Adsorption Performance Of Hnmmentioning

confidence: 99%

Designing hierarchical nanoporous membranes for highly efficient gas adsorption and storage

et al. 2020

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Nanoporous membranes with two-dimensional materials such as graphene oxide have attracted attention in volatile organic compounds (VOCs) and H2 adsorption because of their unique molecular sieving properties and operational simplicity. However, agglomeration of graphene sheets and low efficiency remain challenging. Therefore, we designed hierarchical nanoporous membranes (HNMs), a class of nanocomposites combined with a carbon sphere and graphene oxide. Hierarchical carbon spheres, prepared following Murray’s law using chemical activation incorporating microwave heating, act as spacers and adsorbents. Hierarchical carbon spheres preclude the agglomeration of graphene oxide, while graphene oxide sheets physically disperse, ensuring structural stability. The obtained HNMs contain micropores that are dominated by a combination of ultramicropores and mesopores, resulting in high VOCs/H2 adsorption capacity, up to 235 and 352 mg/g at 200 ppmv and 3.3 weight % (77 K and 1.2 bar), respectively. Our work substantially expands the potential for HNMs applications in the environmental and energy fields.

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“…The type I water adsorption isotherm is characteristic of a hydrophilic material [ 14 , 45 ]. On the other hand, the type IV isotherm showing a sigmoidal course of an adsorption isotherm is usually observed the adsorption of water on hydrophobic porous materials such as aluminum phosphate, zeolite, metal–organic frameworks, and activated carbon [ 46 ]. Therefore, it could be speculated that the active sites of Zr(OH) 4 /GO nanocomposite are more available than those of Zr(OH) 4 , and, as a result, the soman (GD) interacts with more active sites, such that the soman (GD) hydrolysis ability of Zr(OH) 4 could be enhanced even under atmosphere water present at 80% RH.…”

Section: Resultsmentioning

confidence: 99%

Zr(OH)4/GO Nanocomposite for the Degradation of Nerve Agent Soman (GD) in High-Humidity Environments

Jang¹,

Ka²,

Jung³

et al. 2020

Materials

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Zirconium hydroxide, Zr(OH)4 is known to be highly effective for the degradation of chemical nerve agents. Due to the strong interaction force between Zr(OH)4 and the adsorbed water, however, Zr(OH)4 rapidly loses its activity for nerve agents under high-humidity environments, limiting real-world applications. Here, we report a nanocomposite material of Zr(OH)4 and graphene oxide (GO) which showed enhanced stability in humid environments. Zr(OH)4/GO nanocomposite was prepared via a dropwise method, resulting in a well-dispersed and embedded GO in Zr(OH)4 nanocomposite. The nitrogen (N2) isotherm analysis showed that the pore structure of Zr(OH)4/GO nanocomposite is heterogeneous, and its meso-porosity increased from 0.050 to 0.251 cm3/g, compared with pristine Zr(OH)4 prepared. Notably, the composite material showed a better performance for nerve agent soman (GD) degradation hydrolysis under high-humidity air conditions (80% relative humidity) and even in aqueous solution. The soman (GD) degradation by the nanocomposite follows the catalytic reaction with a first-order half-life of 60 min. Water adsorption isotherm analysis and diffuse reflectance infrared Fourier transform (DRIFT) spectra provide direct evidence that the interaction between Zr(OH)4 and the adsorbed water is reduced in Zr(OH)4/GO nanocomposite, indicating that the active sites of Zr(OH)4 for the soman (GD) degradation, such as surface hydroxyl groups are almost available even in high-humidity environments.

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Modeling of type IV and V sigmoidal adsorption isotherms

Abstract: Interpretation of type IV adsorption isotherms not by a composed but unified concept.

Cited by 150 publications

References 76 publications

Graphene oxide integrated silicon photonics for detection of vapour phase volatile organic compounds

Graphene oxide integrated silicon photonics for detection of vapour phase volatile organic compounds

Designing hierarchical nanoporous membranes for highly efficient gas adsorption and storage

Zr(OH)4/GO Nanocomposite for the Degradation of Nerve Agent Soman (GD) in High-Humidity Environments

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