Specific effects of divalent cation nitrates on the nanotribology of silica surfaces

Bogdan C. Donose, Ivan Uriev Vakarelski, Elena Taran, Hiroyuki Shinto, Ko Higashitani*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Recent investigations have shown that hydrated layers of monovalent cations adsorbed on silica (Donose, B. C.; Vakarelski, I. U.; Higashitani, K. Silica surfaces lubrication by hydrated cations adsorption from electrolyte solutions. Langmuir 2005, 21, 1834) or mica (Raviv, U.; Klein, J. Fluidity of bound hydration layers. Science 2002, 297, 1540) surfaces can act as highly efficient boundary lubricants. Here, by using the lateral force microscopy (LFM) mode of atomic force microscopy (AFM), we extended these investigations to the case of divalent cations, measuring the frictional force between a completely hydrophilic silica particle and a silica wafer in Ba2+, Sr 2+, Ca2+, and Mg2+ nitrate solutions. The measurements demonstrated strong lubrication effects for solutions of Ba 2+, Sr2+, and Ca2+ nitrates starting even at a very low electrolyte concentration, such as 3 × 10-5 M. As for Mg2+ ions, however, it is surprising to know that the frictional force increases with increasing electrolyte concentration. Possible nanotribological mechanisms are discussed, and the value of friction was found to be more closely related to the average residence time of water molecules around cations than to the number of water molecules in their hydration shell.

Original languageEnglish (US)
Pages (from-to)7035-7041
Number of pages7
JournalIndustrial and Engineering Chemistry Research
Volume45
Issue number21
DOIs
StatePublished - Oct 11 2006

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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