Adsorption of alkyltrimethylammonium bromide surfactants at the air/water interface

• Published in: International journal of heat and mass transfer Vol. 106; pp. 1035 - 1040
• Main Authors: Nguyen, Cuong V., Nguyen, Thanh V., Phan, Chi M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2017; Elsevier BV
• Subjects: Adsorption; Carbon; Cations; Dynamic adsorption; Dynamic models; Isotherms; Studies; Surface tension; Surfactants; Trimethylammonium bromide; Dynamic adsorption; Surface tension; Trimethylammonium bromide
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2016.10.075

[Display omitted] •C15TAB was synthesized.•Dynamic surface tension was modelled for C14, C15 and C16TAB.•Dynamic modelling confirms that the adsorption has not reached saturation.•Adsorption efficiency is linearly correlated with carbon tail.•Adsorption effectiveness is non-linearly correlated with carbon tail. The dynamic behavior of three trimethylammonium bromide surfactants, C14TAB, C15TAB and C16TAB, was studied by a dynamic modeling framework, which consists of the Ward and Tordai equation and an adsorption isotherm. Three adsorption isotherms, Langmuir, Henry and Freundlich, were used separately. The simplest isotherm, Henry isotherm, could not fit experimental data. Freundlich isotherm can model C15TAB and C16TAB adsorption, but failed to describe C14TAB. On the other hand, Langmuir isotherm was able to model all three surfactants. The results confirmed that the adsorption isotherm is monotonic but non-linear for all surfactants. In the other words, the surfactants have not reached the saturation at the CMC. The results also demonstrated a monotonic correlation between carbon length and adsorption effectiveness of the cationic surfactants. The new insights are important for designing new cationic surfactants.