INVERSE GAS-CHROMATOGRAPHIC STUDY OF ACTIVATED CARBONS - THE EFFECT OF CONTROLLED OXIDATION ON MICROSTRUCTURE AND SURFACE CHEMICAL FUNCTIONALITY

Activated carbons derived from four different source materials were subjected to controlled oxidation by nitric acid, and their resulting microstructure and surface chemical groups were studied. Classical titration procedures indicated the acid/base character of the carbons and inverse gas chromatography was used to study other properties. We find that carboxylic groups are the primary acidic functionality added by oxidation and that these groups can be removed by high temperature treatment without altering the microstructural changes induced by oxidation. Nitric acid treatment of these carbons produces highly acidic carbonaceous materials, and in some cases modifies microstructure. We conclude that inverse gas chromatography at infinite dilution, along with the procedures outlined, provides a convenient way to study the effects of surface modification procedures on the structure and surface chemical properties of porous adsorbents. © 1992.