SORBENT EVALUATION FOR DIFFUSIVE MONITORING OF ENVIRONMENTAL CONTAMINANTS

The adsorption characteristics of several adsorbate-adsorbent systems were analysed to obtain a better understanding of the parameters invol ved in the selection of adequate sorbents for diffusive sampling. Nitr ogen adsorption was used to establish the porous texture of the adsorb ent. Gas-solid chromatography and immersion calorimetry were used for studying the adsorption interactions of benzene and n-hexane with the adsorbent surfaces. In this way, specific retention volumes, isostatic heats of adsorption at low surface coverage and immersion heats for b enzene and n-hexane were determined. The results obtained showed the i mportant role of micropore volumes for a strong interaction of the ads orbents with the adsorbates. Chromosorb 106 and activated carbon were the best adsorbents for benzene and n-hexane when tube-type samplers a nd thermal desorption-gas chromatography were used.