LAUSR

Abstract Mixed micelle plays an imperative role in the solution chemistry and surface chemical applications. Conductivity measurement technique has been employed for studying the association properties of the mixed systems of two important cationic surfactants (cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB)) in absence/attendance of different electrolytes at varying temperatures. The physicochemical characteristics were examined in H2O and electrolytes solution (NaCl, Na2CO3 and Na3PO4) having identical ionic strength (I = 10 mmol kg−1) for pure TTAB and CTAB together with their mixture. In occurrence of electrolytes solution, the quantitative values of critical micelle concentration (cmc) are observed below the values obtained from the aqueous medium for pure along with mixed amphiphiles. The anions effectiveness in lowering the cmc value followed the order: PO43− > CO32− > Cl−. The cmcid values are found higher than the experimentally determined cmc values which suggest the subsistence of attractive interaction amid both amphiphiles. CTAB micellar mole fraction was assessed via applying specific recommended models such as Rubingh (X1Rub), Motomura (X1M), Rodenas (X1Rod) and their results suggest that the more contribution of CTAB in mixed micelles, and their values increase by enhance of concentration of CTAB. The activity coefficients (f1 and f2) values were observed to be beneath unity along with the negative β values for the entire cases viewing synergism (attractive) behavior. The negative Gibbs free energy (ΔG°m) values indicated the spontaneous association phenomena.