Mechanism and Kinetics of the OH Radical Reaction with Formaldehyde Bound to an Si(OH)4 Monomer
In this work, quantum chemical methods are used to studythe reaction of OH radicals with formaldehyde bound to the Si(OH)4monomer, as a model for silica mineral aerosols. The potential energysurfaces for the formaldehyde interaction with the surface modelhave been carefully spanned, and minima and...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2008 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Redalyc-UAM |
| OAI Identifier: | oai:redalyc.org:47552106 |
| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=47552106 |
| Access Level: | acceso abierto |
| Palabra clave: | Química OH radicals formaldehyde rate constants Mineral aerosols radical reactions |
| Sumario: | In this work, quantum chemical methods are used to studythe reaction of OH radicals with formaldehyde bound to the Si(OH)4monomer, as a model for silica mineral aerosols. The potential energysurfaces for the formaldehyde interaction with the surface modelhave been carefully spanned, and minima and maxima were evaluated.Both the H-abstraction and OH-addition paths are shown to becomplex reactions, which involve the formation of a reactant complexin the entrance channel and a product complex in the exit channel. Inthe main reaction channel, formaldehyde binds to the silanol groupsand then reacts with OH free radicals to form a water molecule anda bound formyl radical. We show that the rate constant for the Habstractionreaction is an order of magnitude smaller when formaldehydeis bound to Si(OH)4 than in the gas phase, while the rate constantfor the addition reaction is still about five orders of magnitudesmaller. Thus, the branching ratio between abstraction and addition isnot significantly altered in the presence of the silicate surface model. |
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