The surface tension of aqueous mixtures of dodecyltrimethylammonium tetrafluoroborate (DTABF4) and sodium tetrafluoroborate (NaBF4) was measured as a function of total molality and composition of DTABF4 at 298.15 K. The results were analyzed by originally developed thermodynamic equations and compared with those of dodecyltrimethylammonium bromide (DTAB)-sodium bromide (NaBr) mixed system. It was indicated that BF 4- ions reduce the repulsion between DTA+ ions more effectively than Br- ions in the adsorbed film. To investigate this difference more closely, the surface tension of DTAB-NaBF4 and DTABF4-NaBr mixed system was also measured. The data analysis revealed that BF4- ions are adsorbed positively even for the pure NaBF4 system and preferentially to Br- ions in these mixtures. Furthermore, it was concluded that the side-by-side arrangement suggested in the adsorbed film of 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIMBF4) is due to not only the positive adsorption of BF 4- ions but also the capability of hydrogen bond formation between imidazolium ion and BF4- ions.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Polymers and Plastics
- Colloid and Surface Chemistry
- Materials Chemistry