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The Effects of Dynamic Noncovalent Interaction between Surfactants and Additional Salt on the pH‐Switchable Interfacial Tension Variations
Author(s) -
Zou Jian,
Liu Yigang,
Wang Qiuxia,
Liu Hao,
Jia Han,
Lian Peng
Publication year - 2020
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1002/jsde.12342
Subject(s) - chemistry , pulmonary surfactant , sodium dodecyl sulfate , surface tension , bromide , adsorption , sulfonate , protonation , inorganic chemistry , hydrophobic effect , salt (chemistry) , sodium , chromatography , organic chemistry , ion , thermodynamics , biochemistry , physics
The dynamic noncovalent interaction between the anionic surfactant sodium dodecyl benzene sulfonate (SDBS) and 1,3‐diphenylguanidine (DPG) was employed to control the interfacial activity of the surfactant. At high HCl concentration (1000 mg L −1 ), the SDBS/DPG n+ system could reduce the water/oil interfacial tension (IFT) to 10 −4 mN m −1 order of magnitude, which was much lower than the IFT values in the SDBS/DPG + system with a low HCl concentration (100 mg L −1 ) and the individual SDBS system by three and four orders of magnitude, respectively. The pH‐switchable protonation of amido groups in DPG molecules determines the SDBS/DPG molecular interaction and the amplitude of IFT reduction, which was confirmed by control experiments using two other surfactants (sodium dodecyl sulfate [SDS] and dodecyl trimethylammonium bromide [DTAB]). Moreover, the investigation of the NaCl and temperature effects on the IFT indicated the intensity of mixed SDBS/DPG n+ adsorption layers at the water/oil interface.