HR: 17:15h
AN: V14B-06    [Abstracts]
TI: The Structure of Water around Hematite Nanoparticles
AU: * Spagnoli, D
EM: dspagnoli@berkeley.edu
AF: University of California, Berkeley, Department of Earth and Planetary Sciences, Berkeley, CA 94720, United States
AU: * Spagnoli, D
EM: dspagnoli@berkeley.edu
AF: Lawrence Berkeley National Laboratory, Earth Science Division, Berkeley, CA 94720, United States
AU: Banfield, J F
EM: jbanfield@berkeley.edu
AF: University of California, Berkeley, Department of Earth and Planetary Sciences, Berkeley, CA 94720, United States
AU: Waychunas, G A
EM: gawaychunas@lbl.gov
AF: Lawrence Berkeley National Laboratory, Earth Science Division, Berkeley, CA 94720, United States
AU: Gilbert, B
EM: bgilbert@lbl.gov
AF: Lawrence Berkeley National Laboratory, Earth Science Division, Berkeley, CA 94720, United States
AB: The interactions between water and mineral surfaces are crucial for stabilizing surface structures [1] and mediating interfacial adsorption reactions of aqueous ions [2]. Nanoscale minerals, such as the iron oxides, are extremely common natural products of biomineralization and chemical weathering reactions. Although frequently a minority fraction, mineral nanoparticles can have a profound impact on their environment, having high surface areas and hence high reactivity and total energy relative to macroscopic minerals. Therefore an understanding of the interfacial region between water and nanoparticles is crucial in determining its transport and reactivity. Computer simulations has provided a useful tool in understanding the structure of water on mineral surfaces on the atomistic level [3]. Previous studies has focused on the structure of water on 2-dimentional flat surfaces [2, 3], however, we use molecular dynamics simulations to describe the structure of water around 3-dimensional hematite nanoparticles. We will show that the layering of water is very ordered and begin to evaluate the orientation of water molecules at different positions around the surface. We will describe how the change in surface charge can affect, not only the order and orientation of water, but also the transport of aqueous ions to the surface. In the final part we evaluate how the structure of water can influence aggregation of two or more hematite nanoparticles and suggest a mechanism to oriented aggregation growth. [1] H. Z. Zhang, B. Gilbert, F. Huang, and J. F. Banfield, Nature 424, 1025 (2003). [2] S. Kerisit, and S. C. Parker, J. Am. Chem. Soc. 126, 10152 (2004). [3] D. Spagnoli, D. J. Cooke, S. Kerisit, and S. C. Parker, J. Mater. Chem. 16, 1997 (2006).
DE: 1009 Geochemical modeling (3610, 8410)
DE: 1042 Mineral and crystal chemistry (3620)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting