Adsorption of dimethyl sulfide vapors by activated carbons

Adsorption isotherms of dimethyl sulfide vapors have been studied on two samples of granulated and two samples of fibrous activated carbons having different surface areas and associated with varying amounts of carbon-oxygen surface groups. The adsorption isotherms follow the Langmuir isotherm equation. The adsorption generally increases with increase in surface area and is strongly influenced by the presence of carbon-oxygen groups on the carbon surface. The adsorption increases on oxidation of the carbon surface which enhances the amounts of these surface groups and decreases gradually when these surface groups are eliminated on heat treatment in vacuum at 400 degrees, 650 degrees, and 950 degrees C. The adsorption of dimethyl sulfide obeys first order kinetics. The isosteric enthalpy of adsorption decreases with increase in surface coverage tending to be almost constant at higher surface coverages. The adsorption results suggest that the adsorption of dimethyl sulfide by activated carbons involves specific interactions between the surface acidic groups and the dimethyl sulfide molecules through chemical or quasichemical forces involving hydrogen bonding. (C) 2008 Elsevier B.V. All rights reserved.