Acta Phys. -Chim. Sin. ›› 2007, Vol. 23 ›› Issue (07): 1047-1052.doi: 10.3866/PKU.WHXB20070716

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Adsorption Kinetics of Asymmetric Gemini Surfactants at Air/Water Interface

ZHOU Tian-Hua; ZHAO Jian-Xi   

  1. Department of Applied Chemistry, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002, P. R. China
  • Received:2007-01-29 Revised:2007-03-07 Published:2007-07-03
  • Contact: ZHAO Jian-Xi


Asymmetric Gemini surfactants CmH2m+1OCH2CH(OH)CH2N+(CH3)2C8H17Br, referred to as CmOhpNC8 (m=10, 12 and 14), were synthesized. This type of surfactant molecule has a head region (a hydroxyl and a quaternary ammonium linked by one methylene group) with a small size and two alkyl chains with different lengths. The maximum bubble pressure technique was used to investigate the adsorption kinetics of CmOhpNC8 aqueous solution below their critical micelle concentrations at the air/water interface. The results showed an obvious kinetic process for the adsorption of CmOhpNC8. When CmOhpNC8 were adsorbed on the freshly formed interface, the adsorption process was pure diffusion controlled.When some molecules existed at the interface, the adsorption barrier (Ea) appeared, which reduced with increasing m. This indicated that those molecules with long alkyl chain migrated more easily from the subsurface into the surface, which was attributed to enhanced hydrophobic interaction between the alkyl chains with
increasing m.

Key words: Asymmetric Gemini surfactants, Adsorption kinetics, Hydrophobic interaction


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