COLL 285 |
| Alkyl halides of both biogenic and anthropogenic origin play an important role in atmospheric chemistry as a source of organic chlorine and bromine in the atmosphere. In this study, we focus on the solvation of alkyl halides at the air/water interface. Using classical molecular dynamics simulations, we have studied various alkyl chlorides and bromides, from methyl chloride (CH3Cl), methyl bromide (CH3Br), and bromoform (CHBr3) up to butyl chloride (C4H9Cl) and butyl bromide (C4H9Br), solvated in/on a neat water slab as well as in/on an aqueous sodium bromide solution slab. Results obtained for alkyl halides are compared to those obtained for the corresponding alcohols, and significant differences between alkyl halides and alcohols are observed. The results provide a molecular level insight into the residence and surface organization of alkyl halides on the surface of water as well as into the salting-out effect of the salt ions on the hydrated alkyl halides. At the same time, unlike for the corresponding alcohols, the addition of alkyl halides to an aqueous sodium bromide solution does not modify the interfacial profile of the ions, leaving the surface enhancement of bromide anions unchanged. |
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The Physical Chemistry of Environmental Interfaces
9:00 AM-1:10 PM, Tuesday, April 8, 2008 Morial Convention Center -- Rm. 225, Oral
Division of Colloid & Surface Chemistry |