Adsorption and catalytic decomposition of methyl bromide and methyl iodideon activated carbons

Methyl bromide (MeBr) is commonly used for fumigating structures and commod ities. Emission of MeBr during such treatments is environmentally detriment al because of the reaction of MeBr with stratospheric ozone. In this study we evaluated adsorption of MeBr and methyl iodide (MeI) - a potential MeBr replacement, on five commercial activated carbons, and studied water-initia ted catalytic decomposition of adsorbed fumigants. All carbon samples showe d great adsorption affinity to MeBr and Met, with the adsorption capacity f or Mel several times greater than that for MeBr on the same carbon. For the same fumigant, adsorption was affected by the type of carbon and the conce ntration of fumigant. Water initiated decomposition of both fumigants, libe rating Br- or I- as a transformation product. The rate of decomposition inc reased with increasing temperature, and was also influenced by the carbon t ype. The half-lift: of MeBr or Mel on Centaur, a catalytically modified car bon, was < 2 h at 80 C. The rapid decomposition of MeBr and Mel on wet carb ons at elevated temperatures may be used to detoxify these fumigants after adsorption on activated carbons. (C) 2001 Elsevier Science Ltd. All rights reserved.