化学学报 ›› 2011, Vol. 69 ›› Issue (9): 1035-1040. 上一篇    下一篇

研究论文

加盐导致的全氟辛酸盐表面活性的反常行为

周洪涛1,高岸涛2,邢航3,勾志明3,肖进新*,3   

  1. (1中国石油大学(华东)石油工程学院 青岛 266555)
    (2北京理工大学化学系 北京 100081)
    (3北京氟乐邦表面活性剂技术研究所 北京 100080)
  • 投稿日期:2010-10-13 修回日期:2010-12-10 发布日期:2011-01-07
  • 通讯作者: 肖进新 E-mail:xiaojinxin@pku.edu.cn

Abnormal Surface-Active Behavior of Perfluorooctanoates Induced by Salt

Zhou Hongtao1 Gao Antao2 Xing Hang3 Gou Zhiming3 Xiao Jinxin*,3   

  1. (1 College of Petroleum Engineering, China University of Petroleum (Huadong), Qingdao 266555)
    (2 Department of Chemistry, Beijing Institute of Technology, Beijing 100081)
    (3 Beijing FLUOBON Surfactant Institute, Beijing 100080)
  • Received:2010-10-13 Revised:2010-12-10 Published:2011-01-07
  • Contact: 进新 肖 E-mail:xiaojinxin@pku.edu.cn

通过测定全氟辛酸铵(APFO)、全氟辛酸三甲铵(TMHPFO)、全氟辛酸三乙铵(TEHPFO)在不同浓度NaCl (0.1, 0.3, 0.5 mol•L-1)存在时水溶液的表面张力曲线, 考察不同反离子的氟表面活性剂其表面活性随无机盐浓度的变化. 结果表明, NaCl对APFO的胶束化有明显的促进作用|对于TMHPFO和TEHPFO则在NaCl浓度较低时有很小的促进作用, NaCl浓度较高时由于Na和N(CH3) (或N(CH2CH3) )之间的离子交换作用反而临界胶束浓度(cmc)增大. APFO, TMHPFO的最低表面张力(γcmc)随着NaCl浓度的增大而增大. 而对于TEHPFO, 少量NaCl的加入有利于降低γcmc、然后随着NaCl浓度的增大TEHPFO的γcmc增大. 这说明, 加盐溶液中始终存在着屏蔽效应和离子交换作用的竞争, 随着NaCl浓度增大离子交换趋势增大|对于疏水性较高的三乙铵离子在NaCl存在的情况下离子交换作用导致的γcmc升高需要更高的NaCl浓度才能显现. 通常认为外加无机盐是增强表面活性剂的表面活性的方法之一, 本工作表明, 对于有些反离子为有机阳离子的氟表面活性剂, 外加无机盐, 如NaCl, 不仅不能起到显著的增效作用, 浓度大时甚至会降低表面活性剂的效能. 所以这类表面活性剂在实际使用时应尽量避免高盐环境.

关键词: 氟表面活性剂, 反离子, 盐效应, 表面张力, 离子交换

The surface tension of the aqueous solutions of ammonium perfluorooctanoate (APFO), trimethylammonium perfluorooctanoate (TMHPFO) and triethylammonium perfluorooctanoate (TEHPFO) with the addition of different concentration of NaCl (0.1, 0.3, 0.5 mol•L-1) was measured to investigate the surface activity change of fluorinated surfactants with different counterions upon the addition of inorganic salt. The results showed that, NaCl significantly facilitated the micellization of APFO. While for TMHPFO and TEHPFO, slight promotion on their micellization was found when the concentration of NaCl was low, and when the concentration of NaCl was large, the critical micelle concentration (cmc) increased due to the ion exchange between Naand N(CH3) (or N(CH2CH3) ). The minimum surface tensions (γcmc) of APFO and TMHPFO were increased with the increase of NaCl concentration. For TEHPFO, small amount of NaCl favored to lower γcmc, then γcmc of TEHPFO was increased with the increase of NaCl concentration. It showed that, there was always competition between the shielding effect and ion exchange effect in the solution containing salt, and the tendency of ion exchange became large with the increase of NaCl concentration. For the relatively hydrophobic triethylammonium ions in the presence of NaCl, the appearance of the increase of γcmc induced by ion exchange needed higher concentration of NaCl. Since it is well known that the addition of inorganic salt is one of the methods to enhance the surface activity of surfactants, this work showed that for certain anionic fluorinated surfactants with organic counterions, the addition of inorganic salt such as NaCl could not obviously enhance and even lower the efficiency of surfactants in the case of large concentration of salt. Therefore, this kind of surfactants should avoid the environment of high salinity in application.

Key words: fluorocarbon surfactant, counterion, salt effect, surface tension, ion exchange

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