Reports from Hong Kong University of Science and Technology Highlight Recent Findings in Microporous and Mesoporous Materials (Molecular dynamics study of water and ions transport in nano-pore of layered structure: A case study of tobermorite)
By a News Reporter-Staff News Editor at Science Letter -- Current study results on Microporous and Mesoporous Materials have been published. According to news originating from Hong Kong, People's Republic of China, by NewsRx correspondents, research stated, "Water and ions transport in the cement hydrate determines the durability of cementitious material. Due to the structural similarity, tobermorite, an important mineral analogue of the main phase of cement hydrate, was used to investigate transport behaviour at the molecular level."
Our news journalists obtained a quote from the research from the Hong Kong University of Science and Technology, "In this study, the structural and dynamical properties of the water/ions and the tobermorite interface were studied by the molecular dynamics (MD) simulation method. On the (001) surface of tobermorite, water molecules diffusing in the channel between the silicate chains demonstrate a number of structural water features: large density, good orientation preference, ordered interfacial organization and low diffusion rate. The dipole vector of type 1 water molecules point upwards due to the attraction from the calcium sheet, while type 2 water molecules turn downwards due to the restrained H-bonds donated from O-NB atoms in the silicate chains. The stable H-bonds connected with O-NB in the silicate chains restrict the mobility of the channel water molecules. The significant reduction of the diffusion coefficient matches well with the experimental results obtained by NMR, QENS and PCFR techniques. With increasing distance from the channel, the structural and dynamical behavior of the water molecules vary and gradually translate into bulk water properties at distances of 10-15 angstrom from the liquid-solid interface. In the respect of the ions and tobermorite interaction, there is Cl repulsion and Ca2+ adsorption from the surface."
According to the news editors, the research concluded: "In addition, in simulation time longer than 1 ns, Cl- can diffuse to the surficial Ca2+ and forms the unstable Ca-Cl cluster, which accelerates the desorption of the surface Ca atoms."
For more information on this research see: Molecular dynamics study of water and ions transport in nano-pore of layered structure: A case study of tobermorite. Microporous and Mesoporous Materials, 2014;195():9-20. Microporous and Mesoporous Materials can be contacted at: Elsevier Science Bv, PO Box 211, 1000 Ae Amsterdam, Netherlands. (Elsevier - www.elsevier.com; Microporous and Mesoporous Materials - www.elsevier.com/wps/product/cws_home/600760)
The news correspondents report that additional information may be obtained from D.S. Hou, Hong Kong University of Science & Technology, Dept. of Civil & Environm Engn, Kowloon, Hong Kong, People's Republic of China (see also Microporous and Mesoporous Materials).
Keywords for this news article include: Hong Kong, People's Republic of China, Asia, Microporous and Mesoporous Materials, Molecular Dynamics, Physics
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