Mixed Micellizations of TTAB with Other Surfactants (DTAB, CTAB, Tween-20, Tween-40, and Tween-80)

The critical micelle concentration (CMC) and the counter-ion binding constant (B) for the mixed micellizations of TTAB (tetradecyltrimethylammonium bromide) with other surfactants (DTAB, CTAB, Tween-20, Tween-40, and Tween-80) in aqueous solution of 4-chlorobenzoic acid (0.5 mM) at 25 degrees C were determined as a function of alpha 1 (the overall mole fraction of TTAB) by using the spectrophotometric method and the conductivity method. Various thermodynamic parameters (X-i,gamma(i), C-i,C- a(i)(M), beta, and Delta H-mix) were calculated for each mixed surfactant system and compared with the other mixed surfactant systems by means of the equations derived from the nonideal mixed micellar model. The results show that TTAB/DTAB mixed system has a great positive deviation from the ideal mixed micellar model and the other mixed systems have great negative deviations from the ideal mixed model.