Sorption isotherms of organic vapours on Tenax

Sorption isotherms of o-xylene, n-octane and tetrachloroethene on Tenax were determined at different temperatures, applying vapour concentrations in the range 10-10 000 ppm. In the range up to 120 ppm the isotherms were derived from the results of breakthrough experiments; for the higher concentrations a headspace gas chromatographic method was applied. At lower gas concentrations, corresponding to bed loads of ca. 100 Mymol/g Tenax, the sorption follows the Freundlich equation, whereas in the higher ppm range the isotherms become linear. For the Freundlich part of the isotherms, the isosteric heats of sorption were calculated to be in the range 40-greater than 100 kJ/mol.