SINGLE-COMPONENT AND BINARY-MIXTURE ADSORPTION OF VOLATILE ORGANIC CONTAMINANTS ON SILICA-GEL

Qualitative and quantitative characterization and prediction of multic omponent adsorption equilibria are essential for design of remediation processes such as soil vapor extraction, bioventing, and thermal deso rption. The effects of physical properties of volatile organic compone nts (VOCs) on adsorption equilibria were investigated by measuring sin gle-component and binary-mixture adsorption isotherms on a polar adsor bent, silica gel, employing the frontal analysis chromatography techni que, The binary mixtures were n-hexane/benzene (nonpolar/nonpolar), n- hexane/trichloroethylene (nonpolar/slightly polar), and chloroform/chl orobenzene (polar/polar), The adsorption isotherms for the single comp onents were BET type II isotherms, indicating physical multilayer adso rption. The monolayer uptake increased with the increasing polarity of the components. The adsorption isotherms of the binary mixtures of n- hexane/benzene and n-hexane/trichloroethylene were BET-type II, For th e chloroform/chlorobenzene mixture BET type III isotherms were observe d, The coadsorption of the second adsorbate increased the uptake of th e other adsorbate in all cases. Potential theory, the ideal adsorbed s olution theory (IAS), and the multispace adsorbed solution model (MSAM ) were used for the prediction of binary component isotherms from pure component isotherm data.