Charcoal Sorption Studies: I. The Pore Distribution in Activated Charcoals

McDermot, H. L.; Arnell, J. C.

doi:10.1139/v52-026

Cited by 19 publications

(8 citation statements)

References 1 publication

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“…This value is slightly lower than the total pore volume obtained from SO 2 adsorption and 0.55 cm 3 g –1 from CO 2 adsorption. This difference in total pore volumes has been observed previously for adsorption on activated carbons and was attributed to the lower density of the adsorbed water phase in hydrophobic activated carbons compared with liquid water. − The water vapor adsorption isotherms were analyzed by using the Dubinin–Serpinsky equation . The results calculated for the p / p 0 range 0.2–0.5 showed that the primary surface site concentration from the isotherms averaged 2.12 ± 0.05 mmol g –1 .…”

Section: Resultsmentioning

confidence: 59%

Adsorption of Carbon Dioxide, Water Vapor, Nitrogen, and Sulfur Dioxide on Activated Carbon for Capture from Flue Gases: Competitive Adsorption and Selectivity Aspects

2021

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There is extensive interest in postcombustion flue gas treatment for mitigating CO2 emissions and removal of acid gases. In this study we investigate the adsorption of the main flue gas components (CO2, N2, SO2, and water vapor) on Filtrasorb 400 activated carbon to understand adsorption characteristics of the main components and competitive adsorption effects. The adsorption isotherms of the pure components of flue gas, CO2 (273.15–318.15 K and 0–50 bar), N2 (298.15–313.15 K and 0–150 bar), SO2 (273.15–303.15 K and 0–3.6 bar), and water vapor (293.15–303.15 K and 0–41 mbar), were investigated. The isosteric enthalpies of adsorption were determined to be a function of surface excess. The enthalpies at zero surface coverage have the order SO2 > H2O > CO2 > N2. However, the SO2 isosteric enthalpy decreases with increasing surface excess and is lower than that of water vapor at high surface excess uptake values. The temperature range for CO2 adsorption covers the subcritical to supercritical gas transition. There was no evidence for isosteric enthalpy differences over this temperature range. The adsorption kinetics for SO2 (290.65–303.15 K) and H2O (293.15–303.15 K) adsorption were measured for each isotherm pressure increment. In both cases the adsorption kinetics followed the linear driving force model. The adsorption mechanisms for both SO2 and H2O kinetic trends are discussed in terms of the adsorption mechanisms. The water vapor adsorption kinetics showed a minimum in the region where water molecules form clusters around functional groups, which merge in the pores. The SO2 adsorption kinetics also show a minimum with increasing surface coverage, and this is attributed to dipole–dipole interactions. The activation energies for diffusion of both SO2 and H2O into F400 were very low. Both the N2 and CO2 adsorption kinetics were too fast to be measured accurately by the gravimetric method used in this study. Ideal adsorbed solution theory (IAST) was used to calculate competitive adsorption of SO2/CO2 and CO2/N2 from the isotherms of the pure components. The competitive adsorption of CO2/N2 was investigated by using the integral mass balance (IMB) experimental method, and this was used for validation of the IAST. The results provide an insight into the role of competitive adsorption in the capture of CO2 and SO2 from flue gases by adsorption from both thermodynamic and kinetic perspectives.

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Section: Resultsmentioning

confidence: 59%

Adsorption of Carbon Dioxide, Water Vapor, Nitrogen, and Sulfur Dioxide on Activated Carbon for Capture from Flue Gases: Competitive Adsorption and Selectivity Aspects

2021

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“…0.6 mL/g) accessible to SFe only at higher temperatures (see Table I). The truly carbonaceous nature (nonoxidized) is noted in the hydrophobic character of the water isotherm (Figure 5) (12). These results also show that sorption of sulfur hexafluoride will not be markedly hindered by sorbed water as long as the relative humidity is kept appreciably below ~50%.…”

Section: Resultsmentioning

confidence: 64%

Sorption of sulfur hexafluoride by activated charcoal

Fuller¹,

Clinton²,

Fallon³

et al. 1981

J. Chem. Eng. Data

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“…5 Pore volume filling occurs at high relative pressure but the density of the adsorbed water is usually lower than that of the liquid. [6][7][8][9] This has been ascribed to the inability of adsorbed water to form a full threedimensional structure in microporosity. [6][7][8][9] Competitive adsorption is difficult to study because of problems associated with quantifying the uptakes and adsorption dynamics of the various adsorbed species in multicomponent adsorption systems.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9] This has been ascribed to the inability of adsorbed water to form a full threedimensional structure in microporosity. [6][7][8][9] Competitive adsorption is difficult to study because of problems associated with quantifying the uptakes and adsorption dynamics of the various adsorbed species in multicomponent adsorption systems. The amounts adsorbed may be calculated indirectly from a complete set of adsorption isotherms for the total adsorption of the multicomponent system, using various models based on thermodynamic principles, or determined by direct measurement of the amounts of each component adsorbed.…”

Section: Introductionmentioning

confidence: 99%

Multicomponent Vapor Sorption on Active Carbon by Combined Microgravimetry and Dynamic Sampling Mass Spectrometry

2002

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Combined gravimetric and dynamic sampling mass spectrometry methods have been developed for the direct measurement of multicomponent vapor sorption on microporous materials. This method combines the gravimetric method for determination of the kinetics and equilibria of total adsorption, and mass spectrometry for the analysis of each adsorbate component during temperature programmed desorption. Mass spectrometry was also used for the determination of the adsorptive gas-phase concentrations during adsorption. Results are presented for adsorption of water/n-octane and water/n-butane on active carbon BAX950 using helium as the carrier gas. Marked differences were observed in the amount of water vapor adsorbed in the presence of n-butane compared with static water vapor and water vapor in helium. The dynamics of adsorption and desorption resulting from competitive adsorption have been investigated. The kinetics are compared with data for single component adsorption of static vapors and flowing vapors in helium. The results are discussed in terms of the diffusion processes and adsorption mechanism.

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Charcoal Sorption Studies: I. The Pore Distribution in Activated Charcoals

Cited by 19 publications

References 1 publication

Adsorption of Carbon Dioxide, Water Vapor, Nitrogen, and Sulfur Dioxide on Activated Carbon for Capture from Flue Gases: Competitive Adsorption and Selectivity Aspects

Adsorption of Carbon Dioxide, Water Vapor, Nitrogen, and Sulfur Dioxide on Activated Carbon for Capture from Flue Gases: Competitive Adsorption and Selectivity Aspects

Sorption of sulfur hexafluoride by activated charcoal

Multicomponent Vapor Sorption on Active Carbon by Combined Microgravimetry and Dynamic Sampling Mass Spectrometry

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