Effect of Surface Groups on Adsorption of Pollutants

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Environmental Protection Agency, Water Quality Office, 1970 - 29 páginas

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Página 4 - NaHCO3, etc. Accordingly, simple titration with different bases serves to identify the acidic surface oxides present on a given sample of carbon. It is possible to produce these acidic functional groups by oxidation in air or pure oxygen or by mixing the carbon sample with aqueous solutions of oxidizing agents like NaOCl, KMnO4, or (NH^SzOg.
Página 3 - Fig. 1. A graphite layer, which may be regarded as analogous to a very large, polynuclear aromatic molecule contains carbon atoms joined by a bonds to three neighboring carbon atoms with the fourth electron of each atom participating in a ^-bond (up2 hybridization).
Página 3 - TTelectron system, except where they are bound at lattice defects. Most important and best known among the surface compounds of carbon are those with oxygen and sulfur, although other elements such as chlorine and hydrogen can also combine with elemental carbon. Of these compounds the surface oxides...
Página 29 - Role of surface acidity in the adsorption of organic pollutants on the surface of carbon.
Página 4 - Boehm (6) has pointed out that they are formed after an outgassed carbon surface comes into contact with oxygen after cooling in an inert atmosphere. Of the many techniques for characterizing the acidic surface oxides of carbon, the method used extensively by Boehm, Diehl, et al.
Página 4 - It is also possible to partially remove the acidic functional groups by reduction or vacuum outgassing at elevated temperatures. In addition, these groups can be made to react in other ways such as esterification, formation of acid chlorides, and acetylation. MATERIALS AND METHODS Three different microcrystalline carbons were employed in this work: (1) an active carbon "Columbia Carbon LC325...
Página 3 - free valences" at the edges of the graphitic layer planes of microcrystalline carbon are very reactive and form compounds with any suitable foreign atoms present. It follows that functional groups or surface compounds can be expected almost exclusively at the layer edges; foreign atoms or molecules can be only weakly adsorbed on the basal faces by means of the graphitic TTelectron system, except where they are bound at lattice defects.

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