Effect of the extent of oxidation of activated carbons by O2 and HNO3 on the acidity and composition of surface functional groups and their ion-exchange properties

The Hydrophobisation of Activated Carbon Surfaces by Organic Functional Groups

“…In the present work, polymer-pyrolysed mesoporous activated carbon SCN (Lahaye et al 1999) and charcoal KAU from fruit stones (Strelko et al 1998) made in-house were modified as follows. To increase the surface density of hydroxy groups and reduce the amount of uncontrolled impurities, all ACs were oxidised with hydrogen peroxide.…”

“…The hydrophobisation of carbon surfaces for use as catalyst carriers has not yet been explored. Currently, charcoal modification is performed by surface oxidation (Gomez-Serrano et al 1994;Nosyrev et al 1996) or by treatment with sulphating, nitrating or halogenating agents (Wenling et al 1996). In some cases, oxygen-containing groups are removed from the charcoal surface by thermal treatment in argon or an argon-hydrogen mixture (Menendez et al 1997).…”

Proton catalysis with active carbons and partially pyrolyzed carbonaceous materials

“…By taking into account all these conceptual aspects, in [29] we for the first time conducted a comprehensive study of the oxidation degree effect under atmospheric oxygen and nitric acid conditions on the structure and acidity of the surface functional groups of the carbonaceous materials. However, before proceeding to the presentation of these results, we shall first discuss the calculation methods of the ionization constants (pKa values) of oxidized carbon and other carbonaceous materials with surface protonic groups.…”

“…In ref. [29], we investigated how the type of functional groups and their pKa values depend on the degree of oxidation of the carbon surface. The quantitative determination of the different types of functional groups were carried by the Boehm method, i.e., by titrating with NaHCO3, Na2CO3, NaOH, and C2H5ONa solutions.…”

“…Fig.2. pKa values of the surface groups as a function of oxidation degree of the carbon at the initial stage of its neutralization with alkali[29].…”