Mixed micelle formation: Assessment of the impacts of atenolol drug on the physico-chemical parameters of sodium dodecyl sulfate and cetyldimethylethylammonium bromide mixture

This study has explored the micellization characteristics (both pure and mixed forms) of sodium dodecyl sulfate (SDS) and cetyldimethylethylammonium bromide (CDMEAB) mixtures with atenolol (ATL) drug in water (H2O) medium. The conductivity measurements technique was used to examine the micellization behavior of surfactants in the range of temperatures from 293.15 to 318.15 K. The magnitudes of critical micelle concentration (CMC) values were detected to be dependent on the experimental temperatures, mole fractions of components in the surfactant(s)-drug mixtures, and drug concentrations. ATL promoted the micellization process in pure SDS/ CDMEAB surfactant. The attained CMC determined for the SDS + CDMEAB mixtures in aq. ATL medium was found in between the corresponding magnitudes of CMC obtained from SDS and CDMEAB separately, while these values dwindled as the mole fraction of CDMEAB (alpha 1) was raised. The experimental CMC values were less than the ideal magnitude of CMC (CMCid), indicating that attractive interactions existed between SDS and CDMEAB species. Micellar mole fraction (XRub1 ) values determined from the utilization of Rubingh's model illustrated that CDMEAB contribution in the mixed micelle formation increasead as the concentration of CDMEAB was raised gradually. The magnitudes of activity coefficients (fRub 1 and fRub 2 ) obtained below 1 for the surfactants in experimental mixtures which depicted deviations from ideal solutions. The calculated values of interaction parameter (beta m) showed the presence of attractive interaction/synergism within the respective components of SDS+CDMEAB mixtures. The appearance of negative free energy of micellization (Delta G0m) and the excess free energy of micellization (Delta GRub ex ) revealed the spontaneity of the micelle formation process as well as suggested the greater stability of SDS + CDMEAB mixed micelle species in comparison to those obtained from the solutions of individual surfactants respectively. The magnitudes of Delta H0m appeared as positive initially at the lower temperatures, then became negative at higher experimental temperatures which indicated the endothermic nature of micellization at lower temperatures whereas the corresponding process was found to be exothermic at elevated temperatures.