Molecular features of the air/carbonate solution interface

Hao Du, Jin Liu, Orhan Ozdemir, Anh V. Nguyen, Jan D. Miller*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

The nature of the air/carbonate solution interface is considered with respect to water structure by sum-frequency vibrational spectroscopy (SFVS) and molecular dynamics simulations (MDS). Results from this study provide further understating regarding previous observations that the surface tensions of structure making sodium carbonate solutions have been shown to be significantly greater than the surface tensions of structure breaking bicarbonate solutions at equivalent concentrations. This difference in surface tension and its variation with salt concentration is related to the organization of water and ions at the air/solution interface. Spectral results from SFVS show at equivalent concentrations that, for the carbonate solution, the strong water structure signal of 3200 cm-1 at the air/carbonate solution interface is increased by a factor of 4 when compared to the same signal for the air/bicarbonate solution interface, which spectrum is weaker than the spectrum for the air/water interface in the absence of salt. These results from SFVS are explained by the results from MDS which show that in the case of carbonate solutions the structure making carbonate ions are excluded from the interfacial water region which region is extended in depth. On the other hand, in the case of bicarbonate solutions, the bicarbonate ions are accommodated in the interfacial water region and there is no evidence of an increase in the extent of water structure. These SFVS experimental and MD simulation results provide further information to understand interfacial phenomena of soluble salts at the molecular level.

Original languageEnglish
Pages (from-to)271-277
Number of pages7
JournalJournal of Colloid and Interface Science
Volume318
Issue number2
DOIs
Publication statusPublished - 15 Feb 2008
Externally publishedYes

Keywords

  • Carbonate solution
  • Interfacial water structure
  • Molecular dynamic simulation
  • Sum-frequency vibrational spectroscopy
  • Surface tension

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