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MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES
Sawunyama, P. AND G W. Bailey. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES. JOURNAL OF MOLECULAR STRUCTURE: THEOCHEM 541(1-3):119-129, (2001).
Elucidate and model the underlying processes (physical, chemical, enzymatic, biological, and geochemical) that describe the species-specific transformation and transport of organic contaminants and nutrients in environmental and biological systems. Develop and integrate chemical behavior parameterization models (e.g., SPARC), chemical-process models, and ecosystem-characterization models into reactive-transport models.
Non-bonded interactions between model pesticides and organo-mineral surfaces have been studied using molecular mechanical conformational calculations and molecular dynamics simulations. The minimum energy conformations and relative binding energies for the interaction of atrazine, ametryn, prometone, 2,4-D and DDT with rutile, Beta-cyclodextrin, and a Beta-cyclodextrin?rutile aggregate, respectively, were obtained. Relative binding energies for the pesticides on the mineral surface were generally in the order 2,4-D>prometone>ametryn>atrazine>DDT. The favored binding conformation for 2,4-D and DDT was usually one in which the aromatic rings lay parallel to the surface. S-triazines adopted conformations in which the triazine ring was oblique to the surface. On a composite Beta-cyclodextrin-rutile surface, the binding energies did not decrease appreciably although most of the organic contaminants showed a strong preference for the pristine mineral surface.