Molecular-Based Studies of Metal, Metal Oxide and Metal Sulfide Nanoparticle Transformations in the Environment

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In this project funded by the Environmental Chemical Sciences Program in the Chemistry Division at the National Science Foundation, Professor Vicki H. Grassian of the University of California San Diego is investigating how metal-based nanomaterials change and transform in the environment. The proposed activities focus on molecular-based studies to better understand chemical changes in metal, metal oxide and metal sulfide nanoparticles in the environment. Although in the past decade, a number of studies have focused on environmental studies of nanoparticles in their native states, while only a few studies have focused on the molecular details of how nanoparticles can change due to chemical processing in the environment. Nanoparticles can age and undergo transformations under ambient conditions of temperature, relative humidity and in the presence of solar radiation. As these materials age and transform, their properties are altered making it difficult to identify structure?property?function and structure?property?hazard relationships. This research studies the impact of nanoparticle in the environment as well their interactions with biomolecules and biological systems. The broader impact of these studies advance the goals of sustainable nanotechnology and provide a foundation for broadening participation and training and engaging students at all levels through research, teaching and outreach activities. These studies provide students with an opportunity to engage in a highly interdisciplinary research area that involves environmental science, nanoscience, engineering, colloid science, materials and surface chemistry.This research program studies the cxidation of metal and metal sulfide nanoparticles in humid and aqueous environments, carbonate formation of metal oxide nanoparticles in humid environments, and surface ligand reactions (adsorption and displacement) on nanoparticles in aqueous environments. These studies are used to better understand the potential environmental and health implications of nanoscience and nanotechnology and contribute to answering questions concerning the transformation and fate of manufactured nanomaterials. As nanomaterials age and transform, their properties are altered making it difficult to identify structure-property-function and structure-property-hazard relationships. Therefore aging impacts their behavior in the environment as well their interactions with biomolecules and biological systems. In particular, the proposed activities focus on better understanding transformations of metal, metal oxide and metal sulfide nanoparticles (including Cu, CuO, CuS, Ag2S, ZnO ZnS and TiO2) on a molecular level and how these processes impact nanoparticle physicochemical properties important in the environmental, health, and safety (EHS) considerations of these materials.