Visualising the molecular alteration of the calcite (104) - Water interface by sodium nitrate

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • Sascha Hofmann
  • Kislon Voïtchovsky
  • Peter Spijker
  • Moritz Schmidt
  • Thorsten Stumpf

Research units

  • Karlsruhe Institute of Technology
  • Durham University
  • Helmholtz-Zentrum Dresden-Rossendorf

Abstract

The reactivity of calcite, one of the most abundant minerals in the earth's crust, is determined by the molecular details of its interface with the contacting solution. Recently, it has been found that trace concentrations of NaNO3 severely affect calcite's (104) surface and its reactivity. Here we combine molecular dynamics (MD) simulations, X-ray reflectivity (XR) and in situ atomic force microscopy (AFM) to probe the calcite (104) - water interface in the presence of NaNO3. Simulations reveal density profiles of different ions near calcite's surface, with NO3 - able to reach closer to the surface than CO3 2- and in higher concentrations. Reflectivity measurements show a structural destabilisation of the (104) surfaces' topmost atomic layers in NaNO3 bearing solution, with distorted rotation angles of the carbonate groups and substantial displacement of the lattice ions. Nanoscale AFM results confirm the alteration of crystallographic characteristics, and the ability of dissolved NaNO3 to modify the structure of interfacial water was observed by AFM force spectroscopy. Our experiments and simulations consistently evidence a dramatic deterioration of the crystals' surface, with potentially important implications for geological and industrial processes.

Details

Original languageEnglish
Article number21576
Pages (from-to)1-11
JournalScientific Reports
Volume6
Publication statusPublished - 15 Feb 2016
MoE publication typeA1 Journal article-refereed

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