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

Abstract

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.

A Novel Approach for the Removal of Lead(II) Ion from Wastewater Using Mucilaginous Leaves of Diceriocaryum eriocarpum Plant

“…As shown in Figure 1, the band observed at 2924 cm is possibly due to C-H stretching vibrations of saturated aliphatic compounds as reported by Khambathy et al [31] while the band at 1644 cm can be attributed to -NH bending vibration of primary amines [31,32]. A small peak was observed at 1429 cm −1 and corresponds to v(C-C) stretching vibrations of aromatic rings [16].…”

Effects of vacuum pyrolysis conditions on the characteristics of activated carbons derived from pistachio-nut shells

“…The position of hydrogen-bonded OH groups is usually in the range of 3200-3650 cm −1 for alcohols and phenols. The band located at around 2924 cm −1 corresponds to ν(C-H) vibrations in methyl and methylene groups [13]. Moreover, the γ (C-H) vibrational bands for CH 3 and CH 2 are located around 1380 and 1465 cm −1 , which are very useful in identifying the methyl and methylene groups in a given compound [12,14].…”

“…The great significance of this chemical influence has been the subject of many research studies [12][13][14]. Meanwhile, the detailed micrographitic structures, such as the crystallinity of carbons, have not been fully established, although some studies have been carried out in this area [15][16][17].…”

Isotherms, kinetics and thermodynamics for adsorption of pyridine vapors on modified activated carbons

“…The adsorption behavior of pyridine vapor on WK11 ion exchange resin indicated that pyridine could disrupt weak H bonds of original WK11 to form a strong pyridine-COOH hydrogen bond (Chen et al 2004). While the adsorption of pyridine on activated carbons involved physisorption on the oxygen free surface and chemisorption on acidic carbon-oxygen groups (El-Nabarawy and Petro 1997). Rate constants, activation energies and compensation effects indicated that the adsorption involved diffusion barrier at the pore entrance (Yuzak et al 2001).…”