Enhanced Desorption of Atmospheric Samples from Activated Carbon

It has been previously shown that the desorption of either a chemisorbed or a physically adsorbed gas can be enhanced by the subsequent introduction of a foreign gas. Under conditions in which desorption recovery of butane from activated, carbon was 50 to 65%, subsequent adsorption of CCl₄ enhanced the recovery of butane to 100%. Recovery of CCl₂F₂, originally 79%, was enhanced to 99% by the same method. The method of enhanced desorption was applied to the recovery of samples from activated carbons exposed to atmospheres in Chicago, New Orleans, Philadelphia, Washington, D. C, and Cincinnati. Three different types of carbons, characterized by different distributions of pore diameters, were used simultaneously in the Cincinnati sampling. In general, the enhanced desorption technique was advantageous in providing analytical information on adsorbed samples recovered from carbon media. The enhancement effect is especially marked with hydrocarbon material. The effects of these structural attributes of the carbon media are evaluated by detailed consideration of infrared absorptions.