Acta Chimica Sinica ›› 2014, Vol. 72 ›› Issue (5): 615-623.DOI: 10.6023/A14020124 Previous Articles     Next Articles



李亚娉a, 吕韦钦a, 曹绪龙b, 宋新旺b, 王其伟b, 李英a   

  1. a 山东大学化学与化工学院胶体与界面化学教育部重点实验室 济南 250100;
    b 中石化胜利油田地质科学研究院 东营 257015
  • 投稿日期:2014-02-22 发布日期:2014-04-16
  • 通讯作者: 李英
  • 基金资助:

    项目受国家自然科学基金(No. 21173134)和国家科技重大专项(No. 2008ZX05011)资助.

Study of the Synergistic Effect of Sodium Dodecyl Sulfate and Betaine at the Air/Water and Oil/Water Interfaces

Li Yapinga, Lv Weiqina, Cao Xulongb, Song Xinwangb, Wang Qiweib, Li Yinga   

  1. a Key Lab for Colloid and Interface Chemistry of State Education Ministry, Shandong University, Jinan 250100;
    b Geological Scientific Research Institute, Shengli Oilfield, Dongying 257015
  • Received:2014-02-22 Published:2014-04-16
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21173134) and the National Major Science and Technology Project (No. 2008ZX05011).

In this paper, the molecular array behavior of anionic surfactant sodium dodecyl sulfate SDS and zwitterionic surfactant Betaine at the air/water and oil/water interfaces were investigated by molecular simulation approaches, which helped to understand the effects of temperature, salts and the proportion of components on the interfacial activity and foam stability of the mixed binary systems, especially how the multivalent inorganic cations influence the interfacial adsorption behavior of the surfactants and the synergistic effect. The oil/water interfacial tension was not only measured experimentally using TEXAS500 spinning drop interface tension meter, but also calculated theoretically using dissipative particle dynamic (DPD) method. Foam decay method was utilized to determine the foam stability. The array behavior of surfactant molecules at the air/water and oil/water interfaces was described by molecular dynamics (MD) simulation method. It was found that the oil/water interfacial activity of mixed binary system was significantly better than unitary system. The synergistic effect between SDS and Betaine was enhanced when there was Ca2+ or Mg2+ existed in the solution. The radial distribution function of head groups of surfactants around inorganic ions showed that there was very strong interaction between the Ca2+ or Mg2+ and the head groups of SDS and Betaine, which not only induced the increase of the maximum interfacial adsorption quantity of the surfactants, but also adjusted the array states of the surfactant molecules in the interface layer. When the proportion of components of SDS/Betaine binary system was 4:6, the oil/water interfacial activity and foam stability of the binary system both were very good with Ca2+ or Mg2+ existing, even use sea water as medium, which could be a good candidate system for foam system used under high salinity condition. The co-adsorption behavior of the surfactant molecules in the binary system at oil/water interface and the foam films was found to be similar. The simulation results agreed well with the experiment results. The knowledge about the microscopic character of the mixtures of surfactants at interfaces could provide useful guidance for the design and application of surfactants under the condition of high salinity, such as low tension foam flooding system used in offshore EOR.

Key words: interfacial activity, foam stability, synergistic effect, low tension foam system