Acta Phys. -Chim. Sin. ›› 1997, Vol. 13 ›› Issue (05): 438-444.doi: 10.3866/PKU.WHXB19970510

• ARTICLE • Previous Articles     Next Articles

FT-IR Study of Water Structure in Water/AOT/n-Heptane Microemulsion System

Li Quan,Li Wei-Hong,Weng Shi-Fu,Wu Jin-Guang,Xu Guang-Xian   

  1. College of Chemistry and Molecular Engineering,Peking University,Beijing 100871
  • Received:1996-11-27 Revised:1997-01-07 Published:1997-05-15
  • Contact: Wu Jin-Guang

Abstract:

Microstructure of water in water/AOT/n-heptane microemulsion system has been studied using fourier transform infrared spectroscopy (FT-IR). Intensity and peak position of O-H stretching band of water in the system were found to change with water content Wo, i.e. the molar ratio of water to surfactant (H2O/AOT). Intensity of O-H stretching vibration in the range of 3050 and 3750 cm-1 increased with water content and the frequency was also found to vary from 3493 to 3417 cm-1 in the system with increasing Wo values (from 1 to 60). Four types of circumstance of water exist in the microemulsion system located around 3590±20 cm-1, 3520±10cm-1, 3465±10 cm-1 and 3270±20 cm-1 were estimated after O-H stretching bands were resolved by curve fitting. The stretching band of carboxide splitted into two peaks located at 1739±2cm-1and 1722±2 cm-1 and the intensity ratio Ir(I1739/I1722) decreased with water content. These variations are due to both the hydration of head-group and the different conformation in AOT molecule.

Key words: FT-IR;Water, Curve-fitting, sodium bis(2-ethylhexyl) sulfosuccinate(AOT), Microemulsion Solutions