Determination of adsorption of toluene and xylene vapors on activated carbon from corn cob using the gas chromatographic technique

Abstract

Corncob was activated with sulfuric acid, phosphoric acid and zinc chloride solution at 250°c, 300°c, and 600°c, respectively, to produce carbon adsorbents. The activation with zinc chloride provided the highest specific surface area, while that with sulfuric provided the lowest specific surface area. All activation produced non-polar surface. Adsorption equilibrium for dilute benzene, toluene and o-xylene vapor was measured indirectly by chromatographic method at 150-210°c. The increasing sequence of the equilibrium constants and the overall mass transfer coefficients for those vapors on a given carbon adsorbent were o-xylene, toluene and benzene. For a given adsorbate, the equilibrium constant on the carbon adsorbent activated with sulfuric acid was the lowest, while those on the other carbon adsorbents were hundred fold at least. The heats of adsorption of vapors were about 2-3 times heat of condensation.