Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (03): 638-642.doi: 10.3866/PKU.WHXB20100331

• COLLOID AND INTERFACE CHEMISTRY • Previous Articles     Next Articles

Enthalpy-Entropy Compensation of Micellization of Alkyl Aryl Sulfonates in Aqueous Solutions

YU Tao, LI Zhong, DING Wei, LUO Shi-Qiong, LUAN Huo-Xin, TONG Wei, QU Guang-Miao, LI An-Jun, CHENG Jie-Cheng   

  1. Chemistry and Chemical Engineening College, Daqing Petroleum Institute, Daqing 163318, Heilongjiang Province, P. R. China; Daqing Oil Field Company Limited , Daqing 163453, Heilongjiang Province, P. R. China
  • Received:2009-10-14 Revised:2009-12-07 Published:2010-03-03
  • Contact: YU Tao, DING Wei E-mail:yutao915@126.com; dingwei40@126.com

Abstract:

We used a surface tension method to investigate the thermodynamic properties of micellization in aqueous solution for several alkyl aryl sulfonates that were synthesized in our laboratory. The influence of temperature and molecular structure on the micellization is discussed. Results show that the micellization of alkyl aryl sulfonates in aqueous solutions is spontaneous and entropy-driven. As the temperature rises, the micellization is easy initially but then becomes more difficult. The contribution of entropy change to the change in Gibbs free energy tends to decrease but the contribution of enthalpy change to the change in Gibbs free energy tends to increase. The micellization is enthalpy-entropy compensated. The compensation temperature (Tc) is found to be (306±2) K, which is independent of the molecular structure of the alkyl aryl sulfonates. The formation ability and the stability of the micelles increase when the carbon atoms of the short or long alkyl chains on the aromatic rings increase, but decrease as the aromatic rings shift fromthe edge to the middle of the long carbonic chains.

Key words: Alkyl aryl sulfonate, Micellization, Thermodynamics, Entropy-driven, Enthalpy-entropy compensation

MSC2000: 

  • O645