ISSN:
1435-1536
Keywords:
Key words Surface tension
;
Anionic/cationic surfactants
;
Mixed monolayer composition
;
βs interaction parameter
;
Gas–liquid adsorption free energy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The surface tension equations of binary surfactant mixtures are established by combining the Szyszkowski equation for pure surfactant solutions and extended nonideal theory for mixed adsorption. They are then successfully applied to two relatively long-chain anionic/cationic binary surfactant systems: triethanolammonium dodecylpoly(oxyethylene)sulfate, as an anionic species (containing about 2 ethylene oxide units), mixed with dodecyltrimethylammonium bromide or hexadecyltrimethylammonium bromide. The composition of the mixed monolayer is mixing-ratio dependent and is slightly asymmetric: for overall equimolar mixtures, the larger mole fraction in the mixed monolayer is that of the more surface-active ion. The strong synergetic effects observed in the surface tension reduction efficiency are reflected by large negative βs parameters, according to regular solution theory. They can be interpreted by the more negative adsorption free energy of each surfactant and the smaller area occupied by surfactant hydrocarbon chains in the mixed monolayer.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s003960050004
Permalink