Effects of Amine Additives on Critical Micelle Concentration of Ionic Surfactants

Abstract

This paper describes the effect of four types of amine (ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine) as polar additives on the critical Micellar concentrations (CMCs) of ionic surfactants, [cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS)] in buffered solutions (I = 0.1 M KNO3, 0.01 M Tris–TrisH+) at pH 7.00 ± 0.01 by electrical conductivity. It was found that the CMCs of these surfactants all decreased with increasing amine concentrations and the extent of effect followed the sequence: tetraethylenepentamine > triethylenetetramine > diethylenetriamine > ethylenediamine. Based on these results, several empirical linear models were obtained. From the experimental data, it is apparent that the extent of decreasing CMCs of CTAB and SDS by the same amine is roughly similar, and this may be ascribed to the polarity of additives and hydrogen bond interactions.