Thermogravimetric and adsorption studies of oxidized active carbons by using different probe molecules

Two coal-based active carbons were treated with hydrogen peroxide, perchloric acid and nitric acid at room temperature as well as with nitric acid at boiling temperature. This treatment, depending on the chemical nature of oxidizing agent, caused noticeable changes in their surface properties and porous structure. Structural changes caused by oxidative treatment of these carbons were estimated on the basis of nitrogen adsorption isotherms. However, the resulting surface changes were evaluated on the basis of water adsorption isotherms as well as thermogravimetric data for water, n-butanol and n-heptane thermodesorption. It was shown that nitric acid oxidation caused greatest changes in the surface and structural properties of the carbons studied. (C) 2000 Elsevier Science B.V. All rights reserved.