On the nature of surface acid sites of chlorinated activated carbons

Pérez-Cadenas, Agustı́n F.; Maldonado-Hódar, Francisco J.; Moreno‐Castilla, Carlos

doi:10.1016/s0008-6223(02)00353-6

Cited by 134 publications

(84 citation statements)

References 7 publications

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“…Cl(2p) spectra very similar to the that of the flue gas-exposed sample were reported for a sample prepared from a metalized chlorinated organic precursor 19 and for carbons treated with molecular chlorine. 20,21 The published spectrum clearly showed the Cl (2p) peaks (200 and 201.6 eV) attributed to organochlorine, as well as the ionic chloride peak. Similar spectra were also obtained for Norit FGD and North Dakota lignite-derived carbons exposed to flue gas containing much larger amounts of HCl (50 ppm), but did not appear in spectra from a similar carbon exposed to flue gas that did not contain HCl.…”

Section: Olson Crocker Benson Pavlish and Holmesmentioning

confidence: 99%

Surface Compositions of Carbon Sorbents Exposed to Simulated Low-Rank Coal Flue Gases

Olson

Crocker

Benson

et al. 2005

Journal of the Air & Waste Management Association

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Bench-scale testing of elemental mercury (Hg 0 ) sorption on selected activated carbon sorbents was conducted to develop a better understanding of the interaction among the sorbent, flue gas constituents, and Hg 0. The results of the fixed-bed testing under simulated lignite combustion flue gas composition for activated carbons showed some initial breakthrough followed by increased mercury (Hg) capture for up to ϳ4.8 hr. After breakthrough, the Hg in the effluent stream was primarily in an oxidized form (Ͼ90%). Aliquots of selected activated carbons were exposed to simulated flue gas containing Hg 0 vapor for varying time intervals to explore surface chemistry changes as the initial breakthrough, Hg capture, and oxidation occurred. The samples were analyzed by X-ray photoelectron spectroscopy to determine changes in the abundance and forms of sulfur, chlorine, oxygen, and nitrogen moieties as a result of interactions of flue gas components on the activated carbon surface during the sorption process. The data are best explained by a competition between the bound hydrogen chloride (HCl) and increasing sulfur [S(VI)] for a basic carbon binding site.

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Section: Olson Crocker Benson Pavlish and Holmesmentioning

confidence: 99%

Surface Compositions of Carbon Sorbents Exposed to Simulated Low-Rank Coal Flue Gases

Olson

Crocker

Benson

et al. 2005

Journal of the Air & Waste Management Association

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“…Of the surface groups produced along oxidation those involving C-Cl bonding have not been explored in depth; they are commonly introduced by reaction of the carbon with chlorine at moderate temperatures [2,3]. However, the number of studies on oxidation of activated carbon with low cost chemicals such as sodium hypochlorite is scarce and they are mainly devoted to the characterization of the resulting oxygen surface groups but not to chlorine groups [4,5].…”

Section: Introductionmentioning

confidence: 99%

Oxidation of activated carbon with aqueous solution of sodium dichloroisocyanurate: Effect on ammonia adsorption

Molina‐Sabio

Gonçalves

Rodríguez‐Reinoso

2011

Microporous and Mesoporous Materials

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An activated carbon has been oxidized with 1-10 wt% aqueous solutions of sodium dichlororisocyanurate (DCI) to introduce oxygen and chlorine surface groups by chemisorption; the formation of chlorine surface groups is important when the concentration of DCI is high, the modification of the microporosity being small. The range of stability of the groups is wide, from groups decomposing at high temperature to HCl to those groups decomposing simultaneously to HCl and CO at low temperature. The carbon with the highest degree of oxidation was heat treated under propene at 200-300ºC, this facilitating the removal of chlorine groups; thus, all chlorine groups are lost at 250ºC, even those thermally stable up to 800-900ºC. The effect of both treatments on both the hydrophilicity and the capacity to retain ammonia has also been studied. Oxidation increases the hydrophilicity of the carbon, as shown by the evolution of water adsorption and the enthalpy of immersion into water. On the other hand, oxidation increases the removal capacity of ammonia both at equilibrium and dynamic tests. However, the contribution of the chlorine surface groups on the adsorption of water and ammonia is small, the groups decomposing to CO 2 upon temperature programmed decomposition playing a more important role in the retention of both species.

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“…The situation is further complicated because the type of species preferentially adsorbed and the extent of adsorption may depend on the state of ionization of the surface which, in turn, is dependent on the solution pH 24 . If the pH of an effluent cannot be modified (for example, when great volumes of liquid have to be decontamined or when this modification produces an environmental problem), the capture of a contaminant can be enhanced by surface modification of the adsorbent by means of suitable treatments [25][26][27][28][29] . In other cases it is possible to change the pH of the solution in order to improve the adsorption.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of mercury (II) from liquid solutions using modified activated carbons

et al. 2010

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Mercury is one of the most toxic metals present in the environment. Adsorption has been proposed among the technologies for mercury abatement. Activated carbons are universal adsorbents which have been found to be a very effective alternative for mercury removal from water. The effectiveness with which a contaminant is adsorbed by the solid surface depends, among other factors, on the charge of the chemical species in which the contaminant is in solution and on the net charge of the adsorbent surface which depend on the pH of the adsorption system. In this work, activated carbon from carbonized eucalyptus wood was used as adsorbent. Two sulphurization treatments by impregnation with sulphuric acid and with carbon disulphide, have been carried out to improve the adsorption capacity for mercury entrapment. Batch adsorption tests at different temperatures and pH of the solution were carried out. The influence of the textural properties, surface chemistry and operation conditions on the adsorption capacity, is discussed.

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On the nature of surface acid sites of chlorinated activated carbons

Cited by 134 publications

References 7 publications

Surface Compositions of Carbon Sorbents Exposed to Simulated Low-Rank Coal Flue Gases

Surface Compositions of Carbon Sorbents Exposed to Simulated Low-Rank Coal Flue Gases

Oxidation of activated carbon with aqueous solution of sodium dichloroisocyanurate: Effect on ammonia adsorption

Adsorption of mercury (II) from liquid solutions using modified activated carbons

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