The Rate of Adsorption of Phosgene and Chloropicrin on Charcoal

Abstract

Making use of a relationship between the adsorption rate constant and the maximum slope of the effluent concentration-time curves derived from the rate equation of Bohart and Adams, it has been possible to estimate an absolute rate of adsorption of phosgene and chloropicrin on charcoal from the experimental data of Dole and Klotz. It is shown that diffusion to the most accessible part of the charcoal surface will occur faster than the observed rate, but more slowly to the least accessible surface areas. Calculated rates of adsorption using the statistical equations of Glasstone, Laidler, and Eyring and of Temkin are also of the correct order of magnitude when plausible assumptions are made concerning the nature of the activated state. It is concluded that both diffusion and surface reaction mechanisms must be postulated to gain a complete understanding of the adsorption rate of the two gases, but with diffusion being less important in the case of phosgene.