Thermodynamics on the Micellization of CPC/TX-100 Mixed Surfactant System in Aqueous Solutions of KCl

The critical micelle concentration (CMC) of the mixed surfactant system of Cetylpyridinium chloride (CPC) with Triton X-100 (TX-100) in aqueous solutions of KCl were determined by using the UV absorbance method from 15 degrees C to 35 degrees C. Thermodynamic parameters (Delta G(m)degrees, Delta H-m degrees, and Delta S-m degrees), associated with the micelle formation of CPC/TX-100 mixed surfactant system, have been estimated from the temperature dependence of CMC values. The calculated values of Delta G(m)degrees are all negative but the values of Delta S-m degrees are positive in the whole measured temperature region. On the other hand, the values of Delta H-m degrees are positive or negative, depending on the measured temperature.