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

1997 ◽  
Vol 15 (1) ◽  
pp. 47-57 ◽  
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.

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

1995 ◽  
Vol 12 (3) ◽  
pp. 211-219 ◽  
Author(s):  
A.M. Youssef ◽  
A.A. El-Khouly ◽  
A.I. Ahmed ◽  
E.I. El-Shafey
Keyword(s):  
Water Vapour ◽  
Surface Coverage ◽  
Activated Carbons ◽  
Textural Properties ◽  
Isosteric Heat ◽  
Adsorption Properties ◽  
Adsorption Of Water ◽  
Oxygen Groups ◽  
Initial Adsorption ◽  
Entropy Of Adsorption

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.

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

1997 ◽  
Vol 15 (9) ◽  
pp. 707-715 ◽  
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.

scholarly journals Adsorption of Water Vapour by Zinc Oxide, II

1949 ◽  
Vol 70 (1-2) ◽  
pp. 3-4
Author(s):  
Yutaka Miyahara ◽  
Isamu Sano
Keyword(s):  
Zinc Oxide ◽  
Water Vapour ◽  
Adsorption Of Water

Suggested improvements in the parameters used for describing the low relative pressure region of the water vapour isotherms of activated carbons

Carbon ◽  
2013 ◽  
Vol 60 ◽  
pp. 556-558 ◽  
Author(s):  
Peter Lodewyckx ◽  
Encarnación Raymundo-Piñero ◽  
Miroslava Vaclavikova ◽  
Inna Berezovska ◽  
Matthias Thommes ◽  
...  
Keyword(s):  
Water Vapour ◽  
Activated Carbons ◽  
Relative Pressure ◽  
Pressure Region

Water isotherms of activated carbons with small amounts of surface oxygen groups: fitting the mesopore region

Carbon ◽  
2001 ◽  
Vol 39 (2) ◽  
pp. 309-310 ◽  
Author(s):  
P Lodewyckx ◽  
D Van Rompaey ◽  
L Verhoeven ◽  
E.F Vansant
Keyword(s):  
Activated Carbons ◽  
Surface Oxygen ◽  
Surface Oxygen Groups ◽  
Oxygen Groups

Revisiting the Effect of Surface Chemistry on Adsorption of Water on Activated Carbons

1999 ◽  
Vol 103 (19) ◽  
pp. 3877-3884 ◽  
Author(s):  
Issa I. Salame ◽  
Andrey Bagreev ◽  
Teresa J. Bandosz
Keyword(s):  
Surface Chemistry ◽  
Activated Carbons ◽  
Adsorption Of Water ◽  
Effect Of Surface

Experimental Study on Adsorption of Gasoline Vapor on Activated Carbon at High Concentration

2013 ◽  
Vol 807-809 ◽  
pp. 549-552 ◽  
Author(s):  
Chen Lu Zhao ◽  
Wei Qiu Huang ◽  
Ying Xia Wang ◽  
Li Shi
Keyword(s):  
Temperature Rise ◽  
Activated Carbons ◽  
Thermodynamic Characteristics ◽  
High Concentration ◽  
Vapor Adsorption ◽  
Gasoline Vapor ◽  
Adsorption Capacities ◽  
Bed Temperature ◽  
Relationship Of ◽  
The Relationship

Dynamic and thermodynamic characteristics of gasoline vapor adsorption at 0.3 mol/mol on different activated carbons (ACs) were investigated. The adsorption capacities of AC1 and AC3 were 0.295 g/g and 0.189 g/g at 20 oC, and 0.284 g/g and 0.165 g/g at 30 °C, respectively. Bed temperature rise was up to 50°C to 60°C in the adsorption of gasoline vapor at 0.3 mol/mol.The heat effect formula for high concentration vapor adsorption was deduced to evaluate the relationship of the adsorption capacity of the activated carbons, the mole fraction of the inlet gasoline vapor, the recovery efficiency of the gasoline vapor with the temperature rise.

Oxidising Role of Water Vapour in the 250 Kev D+ Induced Radiolysis of Polyimide Kapton-H

1988 ◽  
Vol 100 ◽  
Author(s):  
U. K. Chaturvedi ◽  
A. Patnaik ◽  
Ramji Pathak ◽  
R. N. Chakraborty ◽  
A. K. Nigam
Keyword(s):  
Partial Pressure ◽  
Water Vapour ◽  
Ion Beam ◽  
Adsorbed Water ◽  
Vacuum System ◽  
Residual Water ◽  
Implantation Time ◽  
Polymeric Surface ◽  
Imide Ring

Residual water vapour present in the vacuum system has been observed to play a dominant oxidising role in the 250 keV D+ induced radiolysis of polyimide (Kapton-H). The partial pressure (pp) of water in the vacuum system decreases sharply as the D+ beam impinges the polymeric surface, but soon after, it recovers to its initial value as the accumulated dose increases. Emission of CO2 is observed which has its maximum at a time when the H2O partial pressure is at a minimum. The CO2 level also returns to its original level with time. This complementary variation of CO2 and H2O confirms that absorbed and adsorbed water molecules are radiolysed by the ion beam and initiate oxidation of the radiolytically evolved CO to yield CO2 on and within the ion implanted surface of the polyimide. Further, the small enhancement in the 28 amu peak (N2 + CO), which exhibits no maximum/minimum over the entire implantation time, can be understood in terms of the evolution of N2 from the imide ring as a result of radiolysis of this nitrogen containing polymers.

Adsorption of Water Vapour on a Cleavage Surface of Lithium Fluoride

1962 ◽  
Vol 1 (4) ◽  
pp. 234-234 ◽  
Author(s):  
Koreo Kinosita ◽  
Hiroomi Kojima ◽  
Hideshi Yokota
Keyword(s):  
Water Vapour ◽  
Lithium Fluoride ◽  
Cleavage Surface ◽  
Adsorption Of Water
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