Changes in the Adsorption Properties of Activated Carbon due to Partial Oxidation of the Surface

The textural properties (surface area and porosity) of activated carbons change upon treatment with oxidizing solutions. The extent of this change is related to the strength of the oxidizing agent. Oxidation also changes the chemistry of the surface by forming carbon–oxygen groups which are the sites upon which the initial adsorption of water vapour takes place. The adsorption of water vapour at 300–320 K is mainly physical and the isosteric heat of adsorption decreases continuously as the surface coverage increases. The entropy of adsorption of water vapour on untreated and oxidized carbons, at different adsorption temperatures, has been calculated.

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Adsorption Characteristics of Coal-based Activated Carbons. II. Adsorption of Water Vapour, Pyridine and Benzene

Adsorption Science & Technology ◽

10.1177/026361749701500105 ◽

1997 ◽

Vol 15 (1) ◽

pp. 47-57 ◽

Cited By ~ 21

Author(s):

Th. El-Nabarawy ◽

N.Sh. Petro ◽

S. Abdel-Aziz

Keyword(s):

Free Surface ◽

Water Vapour ◽

Activated Carbons ◽

Potassium Dichromate ◽

Adsorbed Water ◽

Benzene Adsorption ◽

High Concentration ◽

Adsorption Of Water ◽

Acidic Nature ◽

Oxygen Groups

Chemically-activated carbons were prepared by carbonizing Maghara coal with different amounts of phosphoric acid at 873 K. Steam-activated carbons of different burn-off were prepared by gasifying non-activated carbon prepared by carbonization at 873 K with steam at 1173 K. Samples of steam-activated carbons were also treated with concentrated nitric acid or with potassium dichromate. The adsorption of water vapour and benzene was determined at 308 K. The adsorption of pyridine was followed on the chemically-activated carbons at 343 K. The adsorption of water vapour was found to be related to the surface area and the amount of carbon–oxygen groups. Some of the adsorbed water was found to be specifically held to the surface and could be used to determine the number of carbon–oxygen groups on the surface. Two mechanisms are involved in the adsorption of pyridine on the carbons investigated. These are physisorption on the oxygen-free surface and chemisorption on carbon–oxygen groups of an acidic nature. Benzene may be vertically oriented in micropores, horizontally oriented in wider pores and may be even inaccessible to the fraction of the surface located in ultramicropores. Benzene adsorption is also retarded by the existence of a high concentration of carbon–oxygen groups oh the surface.

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Some Surface Properties of Activated Carbons Prepared by Gasification with Different Gases

Adsorption Science & Technology ◽

10.1177/026361749701500907 ◽

1997 ◽

Vol 15 (9) ◽

pp. 707-715 ◽

Cited By ~ 5

Author(s):

Amina A. Attia

Keyword(s):

Carbon Dioxide ◽

Surface Area ◽

Water Vapour ◽

Pore Volume ◽

Activated Carbons ◽

Total Pore Volume ◽

Surface Areas ◽

Adsorption Of Nitrogen ◽

Adsorption Of Water ◽

Different Gases

A non-activated carbon ‘D’ was obtained by carbonizing date pits at 773 K in a limited supply of air. Activated carbons were obtained by gasifying portions of ‘D’ with air at 773 K, carbon dioxide at 1123 K, or steam at 1173 K, all to different burn-offs between 15% and 60%. The adsorption of nitrogen at 77 K and of carbon dioxide at 298 K was investigated using a volumetric adsorption apparatus of a conventional type. The adsorption of water vapour at 298 K and the chemisorption of pyridine at 423 K was followed by means of quartz spring balances. Gasification with oxidizing gases increased the surface area and total pore volume, as measured by nitrogen or carbon dioxide adsorption. In most cases, comparable surface areas were measured by nitrogen and carbon dioxide. The adsorption of water vapour depended on the percentage burn-off and the gasification conditions. Chemisorption of pyridine at 423 K was found to be related to the chemistry of the surface rather than to the surface area or total pore volume.

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Activated carbons from Mongolian coals by thermal treatment

Mongolian Journal of Chemistry ◽

10.5564/mjc.v12i0.174 ◽

2014 ◽

Vol 12 ◽

pp. 60-64

Author(s):

A Ariunaa ◽

J Narangerel ◽

B Purevsuren ◽

R Erdenechimeg

Keyword(s):

Heavy Metal Ions ◽

Bituminous Coal ◽

Activated Carbons ◽

Adsorption Properties ◽

Raw Material ◽

Physical Activation ◽

Distribution Analysis ◽

Surface Oxygen Groups ◽

Oxygen Groups ◽

Coal Grade

Mongolian different rank coals were used as raw material to prepare activatedcarbons by physical activation method. The coal derived carbons were oxidized with nitric acid in order to introduce surface oxygen groups. The ultimate elemental analysis, scanning electron microscopy, surface area, pore size distribution analysis and selective neutralization method were used to characterize the surface properties of activated carbons, oxidizedcarbons and raw coals. The effect of coal grade on the adsorption properties of the carbons were studied. It was concluded that Naryn sukhait bituminous coal could be serve as suitable raw material for production of activated carbons for removal of heavy metal ions from solution.DOI: http://dx.doi.org/10.5564/mjc.v12i0.174 Mongolian Journal of Chemistry Vol.12 2011: 60-64

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CO2 and CH4 Adsorption Behavior of Biomass Based Activated Carbons

10.20944/preprints201807.0489.v1 ◽

2018 ◽

Author(s):

Deneb Peredo-Mancilla ◽

Imen Ghouma ◽

Cecile Hort ◽

Camelia Matei Ghimbeu ◽

Mejdi Jeguirim ◽

...

Keyword(s):

Gas Adsorption ◽

Activated Carbons ◽

Chemical Activation ◽

Textural Properties ◽

Micropore Volume ◽

Adsorption Behavior ◽

Bet Surface Area ◽

Ch4 Adsorption ◽

Oxygen Groups ◽

Physical And Chemical

The aim of the present study is to provide new insights into the CO2 and CH4 adsorption using a set of biomass-based activated carbons obtained by physical and chemical activation of olive-stones. The adsorption behavior is analyzed by means of pure gas adsorption isotherms up to 3.2 MPa at two temperatures (303.15 and 323.15 K).The influence of the activation method on the adsorption uptake is studied in terms of both textural properties and surface chemistry. For three activated carbons the CO2 adsorption was more important than that of CH4. The chemically activation resulted in higher BET surface area and micropore volume that lead to higher adsorption for both CO2 and CH4. For methane the presence of mesopores seems to facilitate the access of the gas molecules into the micropores while for carbon dioxide, the presence of oxygen groups enhanced the adsorption capacity.

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Silica Monolith for the Removal of Pollutants from Gas and Aqueous Phases

Molecules ◽

10.3390/molecules26051316 ◽

2021 ◽

Vol 26 (5) ◽

pp. 1316

Author(s):

Vanessa Miglio ◽

Chiara Zaccone ◽

Chiara Vittoni ◽

Ilaria Braschi ◽

Enrico Buscaroli ◽

...

Keyword(s):

Rhodamine B ◽

Water Solution ◽

Synthesis Method ◽

Textural Properties ◽

Adsorption Properties ◽

Water Soluble ◽

Silica Monoliths ◽

Physico Chemical ◽

Gaseous Toluene ◽

Mcm 41

This study focused on the application of mesoporous silica monoliths for the removal of organic pollutants. The physico-chemical textural and surface properties of the monoliths were investigated. The homogeneity of the textural properties along the entire length of the monoliths was assessed, as well as the reproducibility of the synthesis method. The adsorption properties of the monoliths for gaseous toluene, as a model of Volatile Organic Compounds (VOCs), were evaluated and compared to those of a reference meso-structured silica powder (MCM-41) of commercial origin. Silica monoliths adsorbed comparable amounts of toluene with respect to MCM-41, with better performances at low pressure. Finally, considering their potential application in water phase, the adsorption properties of monoliths toward Rhodamine B, selected as a model molecule of water soluble pollutants, were studied together with their stability in water. After 24 h of contact, the silica monoliths were able to adsorb up to the 70% of 1.5 × 10−2 mM Rhodamine B in water solution.

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