Conductometric study of ionic – nonionic surfactant mixed micelles in aqueous solution

Abstract

This study is concerned with the determination of critical micelle concentration (cmc) of mixed micelle of sodium dodecyl sulfate (SDS) and cetyltriammnum bromid(CTAB) as an ionic surfactants (as anionic and cationic respectively) with Triton x-100 as nonionic surfactant from conductance measurements , the optimal cmc for mixed micelle (SDS/Tritonx-100) and (CTAB/Tritonx-100) at different mole fraction (α) are determined that are 0.2  and 0.6 respectively  .the values of the mole fraction of ionic surfactant in mixed micelle (X₁^M) ,  the activity coefficients of the surfactants 1 and 2 in the micelle (f₁^M    and  f₂^M  )  and the molecular interaction parameter (β^M)  in mixed micelle are determined for two mixed solution in different mole fraction . the standard free energy of micellization for mixing surfactants (ΔGá´¼mic)is calculated by three equation , the values   of free energy  at the optimal α   are  (-20.1   and -31.2 )  Kcal/mole for mixing  (SDS/Tritonx-100) and (CTAB/Tritonx-100) are respectively