Conductivity of sodium dodecyl sulfate (SDS) and sodium lauryl ether sulfate (SLES) surfactants in aqueous and in alcoholic-aqueous mixed solvents (methanol, ethanol, and glycerol) with different mole fractions of alcohols has been measured experimentally at different temperatures (298.15, 303.15, 308.15 and 313.15 K). Surface tension was also measured experimentally for SDS and SLES in aqueous solution at 298.15 K. Critical micelle concentration (CMC) of both SDS and SLES was determined from the measured conductivity and surface tension data. The CMC was found to increase as the temperature and alcohol mole fraction increased in all solvents used. Depending on the conductivity data, the association constant (K a ) of both SDS and SLES was also determined applying Shedlowsky conductance equation. The thermodynamic parameters (ΔG˚, ΔH˚, and ΔS˚) of the micellization and association processes were evaluated from the temperature dependence of micellization and association constants. The results indicate that the association constant of both SDS and SLES decrease as the temperature and alcohol mole fraction increased in all solvents used. Also it was found that CMC and K a of both SDS and SLES increase in the order: methanol > ethanol > glycerol. The association process was found to be spontaneous one. The density and refractive index of both SDS and SLES in aqueous and in alcoholicaqueous mixed solvents (methanol, ethanol, and glycerol) with different mole fractions of alcohols, has been measured experimentally at 298.15 K. Depending on the density data, the molar volume of the two surfactants was determined and discussed. Also depending on the refractive index data, the molar refraction and the polarizability of both SDS and SLES was calculated and discussed. A computer programs were used for all calculations.

This article presents new experimental data about the conductivity and surface of Cocamidopropyl Betaine (CAPB) surfactant in pure H 2 O and organic-H 2 O mixed solvent (methanol, MeOH; ethanol, EtOH and glycerol, GlyOH) media containing various mole fractions of alcohols over the temperature range 298.15 to 313.15 K, in steps of 5 K using conductometric and surface tension measurements. The experimental data for conductivity and surface tension have been used in order to determine the critical micelle concentration (CMC). It has been observed that the CMC increases with increasing temperature and proportion of alcohol. Moreover, the association constant (K a) of CAPB was also determined, depending on the conductivity data, using the Shedlowsky equation. The study showed that, as the temperature and alcohol ratio increased, the association constant of CAPB decreased. In addition, it was found that the CMC increased with MeOH > EtOH > GlyOH and the association behaviour was observed to be spontaneous. The thermodynamics behaviour of (CAPB) surfactant have been thoroughly assessed from the temperature dependence of the micellization and association constants. In all media studied, densities and refractive indices of CAPB were also measured under atmospheric pressure, in the solvents used at T = (298.15 K). The molal volume was estimated based on the density data and some additionally parameters such as molar refraction and the polarizability were also estimated and discussed depending on the refractive index values. These parameters have been utilized to comprehend the association and solvation behaviour of the CAPB surfactant.

The conductivity of both alkyl benzyl dimethyl ammonium chloride (BAC) and cetyl trimethyl ammonium chloride (CTAC) surfactants in water and in alcoholic-water mixed solvents (methanol, ethanol, and glycerol) with different mole fractions of alcohols has been measured at temperatures (298.15, 303.15, 308.15, and 313.15 K). From the measured data of conductivity and surface tension, the critical micelle concentration (cmc) of both BAC and CTAC was determined. The cmc was found to increase as the temperature and alcohol mole fraction increased. From the conductivity values before the cmc, the association constant (K a) of both BAC and CTAC was estimated using Shedlovsky equation. The values of (ΔG, ΔH, and ΔS) of the micellization and association processes were estimated. The association constant of the BAC and CTAC was found to decrease as the temperature and alcohol percentages increase. It was found that the association process is a spontaneous process. At 298.15 K, the density and refractive index of BAC and CTAC in water and in alcoholic-water mixed solvents (methanol, ethanol, and glycerol) with different mole fractions of alcohols have been measured. From the density values, the molal volume of both BAC and CTAC was determined and discussed. Also, from the refractive index values, the molar refraction and polarizability of the surfactants under study were estimated and discussed.

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