Gaseous adsorption of hexamethyldisiloxane on carbons: Isotherms, isosteric heats and kinetics

Wang, Gang; Li, Na; Xin, Xing; Sun, Yong‐Gang; Zhang, Zhongshen; Zhang, Hao

doi:10.1016/j.chemosphere.2020.125862

Cited by 17 publications

(11 citation statements)

References 46 publications

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“…As a typical mesoporous zeolite, the adsorption isotherm of MCM-41 was a typical IV curve with an H1 hesitation loop. 19,20 The pore size distribution curves (Figure 2(b)) also verified the conclusions of the adsorption isotherm. The specific surface areas of PAF-79, MCM-41, AC, and ZSM-5 were 811, 1145, 921, and 361 m 2 g −1 , respectively (Table 1).…”

Section: Resultssupporting

confidence: 70%

Hydrophobic Porous Aromatic Framework as an Adsorbent for Effectively Selective Removal of Aromatic Volatile Organic Compounds

Li,

Wang,

Wang

et al. 2024

ACS EST Eng.

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Adsorption is a widely used technology for controlling volatile organic compound (VOCs) emissions. The significant reduction of the VOCs adsorption capacity of adsorbents under high humidity is currently one of the key factors restricting the practicality of VOCs adsorption technology. In this study, we synthesized a representative PAF, namely, PAF-79, with the objective of investigating its effectiveness in removing VOCs, especially in high-humidity conditions. In dynamic adsorption experiments, due to its abundant micropores, PAF-79 exhibited an exceptional benzene adsorption capacity of up to 147 mg g–1, which is 1.17, 4.85, and 3.08 times that of the activated carbon (AC), MCM-41, and ZSM-5. PAF-79 exhibited impressive hydrophobicity, with an adsorption capacity for benzene reaching 142 mg g–1 under a relative humidity of 75%, which was 97% of its capacity under dry conditions. This performance outshined AC, MCM-41, and ZSM-5 by factors of 1.86, 5.09, and 5.22, respectively. The results of Henry’s constant calculations revealed that water molecules exhibited the weakest partitioning ability on PAF-79, as evidenced by a K H value of 0.036. Furthermore, in competitive adsorption involving two-component VOCs, PAF-79 exhibited high selectivity for polar over nonpolar aromatic VOCs and had 24 times the adsorption capacity for benzene compared to acetone. Moreover, PAF-79 demonstrated excellent reusability, maintaining 98% of its adsorption capacity even after 10 recycles. In conclusion, the notable adsorptive capacity and remarkable resistance to humidity establish PAF-79 as a highly promising adsorbent for VOCs.

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Section: Resultssupporting

confidence: 70%

Hydrophobic Porous Aromatic Framework as an Adsorbent for Effectively Selective Removal of Aromatic Volatile Organic Compounds

Li,

Wang,

Wang

et al. 2024

ACS EST Eng.

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“…In some microporous materials, the isosteric heat is closely related to the adsorption sites of the adsorbent, and its trend is inversely proportional to the adsorption capacity. When the relative pressure of the adsorbate is low, the strong adsorption sites are occupied first, and as the adsorption proceeds, the adsorbent occupies the weaker adsorption sites and the equivalent heat of adsorption decreases with increasing adsorption capacity . For Co-gallate, there is only a local mutation of the coordination structure at the very beginning, exposing a large number of highly active sites, leading to an increase in adsorption capacity and a higher heat of adsorption.…”

Section: Resultsmentioning

confidence: 99%

“…When the relative pressure of the adsorbate is low, the strong adsorption sites are occupied first, and as the adsorption proceeds, the adsorbent occupies the weaker adsorption sites and the equivalent heat of adsorption decreases with increasing adsorption capacity. 39 For Co-gallate, there is only a local mutation of the coordination structure at the very beginning, exposing a large number of highly active sites, leading to an increase in adsorption capacity and a higher heat of adsorption. As the adsorption proceeds, the active sites do not increase again, and C 2 H 4 begins to occupy the weaker adsorption sites, so the isosteric heat decreases as the amount of adsorption increases.…”

Section: Morphological and Structural Characterizationmentioning

confidence: 99%

Guest-Induced Mutation of a Local Coordinative Structure in M-Gallate Metal–Organic Frameworks for Selective Adsorption of Ethylene from Ethane

Jiang

Liu

et al. 2023

ACS Appl. Nano Mater.

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In order to achieve efficient separation of ethylene/ethane systems, the ethylene industry urgently needs efficient adsorbents. The combination of advantages of ultra-microporous restriction and strong affinity from open adsorption sites is expected to achieve highly selective adsorption of ethylene. Herein, we systematically and deeply investigate the gas adsorption behavior of M-gallate series metal−organic framework materials (M = Co, Ni, and Mg). Combined with experimental results such as in situ diffuse reflectance infrared Fourier transform and density functional theory calculation, we successfully proposed an ethylene gas adsorption mechanism based on the local coordinative structure mutation induced by guest molecules. This mechanism suggests that when ethylene molecules are adsorbed, the electronic donor property of π electrons and the d−π feedback effect lead to a shift of the flexible phenolic hydroxyl group and spin state transitions of Co in Co-gallate, thereby exposing the Co site and enhancing the strong affinity to ethylene. The proposed mechanism provides an inspiration and theoretical basis for the subsequent development of efficient selective adsorbents for the separation of ethylene and ethane.

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“…The specific surface area ( S BET ), total pore volume ( V p ), and average pore diameter ( d p ) increased after thermal treatment at 800 °C ( Table 1 ). Both PAC and PAC800 showed a combination of Type I(b) and Type II isotherms with an H4 hysteresis loop, suggesting that their pores consist of micro-, meso-, and macropores [ 50 , 51 ] ( Figure 1 A). However, it is also indicated that the pores of PAC800 have a wider size distribution, as supported by the distribution of mesopores and micropores presented in Figure S2A,B .…”

Section: Resultsmentioning

confidence: 99%

Enhanced Adsorption of Tetracycline by Thermal Modification of Coconut Shell-Based Activated Carbon

Kim

Boldbaatar

2022

IJERPH

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Tetracycline (TC) is one of the most frequently detected antibiotics in various water matrices, posing adverse effects on aquatic ecosystems. In this study, coconut shell-based powdered activated carbon (PAC) was thermally modified under various temperatures to enhance TC adsorption. The PAC subjected to 800 °C (PAC800) showed the best TC adsorption. PAC and PAC800 were characterized using N2 adsorption/desorption isotherm, X-ray photoelectron spectroscopy, Raman spectroscopy, XRD, Boehm titration, and zeta potential analyses. Increases in the specific surface area, C/O ratio, C=O, surface charge, basic groups, and the number of stacked graphene layers along with a decrease in structural defects were observed for PAC800 compared to PAC. The TC adsorption was significantly improved for PAC800 compared to that of PAC, which is attributable to the enhanced electrostatic attraction and π-π EDA interactions induced by the changes in the properties. The Freundlich isotherm was the best fit indicating the heterogeneous nature, and the Freundlich constant of PAC and PAC800 increased from 85.8 to 119.5 and 132.1 to 178.6 (mg/g)‧(L/mg)1/n, respectively, when the temperature was increased from 296.15 to 318.15 K. The kinetics were well described by the pseudo-second-order adsorption model and the rate constant of PAC and PAC800 increased from 0.80 to 1.59 and from 0.72 to 1.29 × 10−3 g/mg‧min, respectively, as the temperature was increased. The activation energy of PAC and PAC800 was 23.7 and 19.6 J/mol, respectively, while the adsorption enthalpy was 196.7 and 98.5 kJ/mol, respectively, indicating endothermic nature. However, it was suggested that TC adsorption onto PAC800 was more favorable and was more contributed to by physisorption than that onto PAC. These results strongly suggest that the properties, adsorption capacity, and adsorption mechanisms of carbonaceous adsorbents can be significantly changed by simple thermal treatment. More, the results provide valuable information about the design of carbonaceous adsorbents with better performance where the structures and functional groups, which positively affect the adsorption, must be improved.

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Gaseous adsorption of hexamethyldisiloxane on carbons: Isotherms, isosteric heats and kinetics

Cited by 17 publications

References 46 publications

Hydrophobic Porous Aromatic Framework as an Adsorbent for Effectively Selective Removal of Aromatic Volatile Organic Compounds

Hydrophobic Porous Aromatic Framework as an Adsorbent for Effectively Selective Removal of Aromatic Volatile Organic Compounds

Guest-Induced Mutation of a Local Coordinative Structure in M-Gallate Metal–Organic Frameworks for Selective Adsorption of Ethylene from Ethane

Enhanced Adsorption of Tetracycline by Thermal Modification of Coconut Shell-Based Activated Carbon

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