Effect of microporosity and oxygen surface groups of activated carbon in the adsorption of molecules of different polarity

Abstract

This work describes the adsorption of molecules with different polarity (N{sub 2}SO{sub 2}H{sub 2}O, and CH{sub 3}OH) on microporous activated carbons with different amounts of oxygen surface groups. The results presented show that both the microporosity and the chemical nature of the carbon surface affect the adsorption process: for nonpolar molecules (i.e., N{sub 2}) the adsorption is mainly influenced by the porous structure, but the nature and amount of oxygen surface groups are extremely important in the adsorption of polar molecules, the more important the higher the polarity of the molecule. On the other hand, there is a noticeable change in the adsorption mechanism of polar molecules at low relative pressures, the change being more drastic for carbons with wide micropores and low content of oxygen surface groups. 20 refs., 9 figs., 4 tabs.