4. Conclusions
We used the isotherms of the surface tension, density, dynamic viscosity and specific conductivity as well as the results of the light scattering measurements for the consideration of the mutual influence of TX-100, CTAB and ethanol on their behavior in the aqueous solutions. From these isotherms it was deduced that ethanol molecules aggregate at some concentration called the critical aggregation concentration (CAC). The values of CAC determinedfrom the isotherms of the surface tension, density and viscosity are nearly the same and do not depend on the composition and concentration of the TX-100 and CTAB mixture. These values are close to those obtained from the same kind of isotherms for the solution of“pure” ethanol. The presence of ethanol aggregates was confirmedby the Zetasizer measurements. Ethanol affects the critical micelle concentration of the TX-100 and CTAB mixture (CMC). The CMC values depend on the composition of the surfactant mixture and and the ethanol concentration. The presence of the mixed micelles was not detected by any method used for the CMC determination at the ethanol concentration higher than CAC. However, the minimum of CMC for each composition of the TX-100 and CTAB mixture was found at low ethanol concentration. The synergetic effect in the micellization process of the TX-100 and CTAB mixtures was also found. The highest synergetic effect appeared at the mole fraction of TX-100 in the mixture with CTAB in the bulk phase equal to 0.8. For such TX-100 and CTAB mixture the mole fraction of sur-factants in the bulk phase was comparable to that in the micelles.At the mole fraction of TX-100 in the bulk phase lower than 0.8 the big increase of its mole fraction in the micelles takes place. The mole fraction of CTAB and TX-100 in the micelles depends also on the concentration of ethanol. It is interesting that the tendency of CTAB to adsorb at the water-air interface is lower than that to form mixed micelles with TX-100. Unexpectedly, the increase of the TX-100 concentration causes the increase of the conductivity of the solution at the same CTAB concentration but only in the range of ethanol concentration in which it is present in the monomeric for min the solution.
4. Conclusions
We used the isotherms of the surface tension, density, dynamic viscosity and specific conductivity as well as the results of the light scattering measurements for the consideration of the mutual influence of TX-100, CTAB and ethanol on their behavior in the aqueous solutions. From these isotherms it was deduced that ethanol molecules aggregate at some concentration called the critical aggregation concentration (CAC). The values of CAC determinedfrom the isotherms of the surface tension, density and viscosity are nearly the same and do not depend on the composition and concentration of the TX-100 and CTAB mixture. These values are close to those obtained from the same kind of isotherms for the solution of“pure” ethanol. The presence of ethanol aggregates was confirmedby the Zetasizer measurements. Ethanol affects the critical micelle concentration of the TX-100 and CTAB mixture (CMC). The CMC values depend on the composition of the surfactant mixture and and the ethanol concentration. The presence of the mixed micelles was not detected by any method used for the CMC determination at the ethanol concentration higher than CAC. However, the minimum of CMC for each composition of the TX-100 and CTAB mixture was found at low ethanol concentration. The synergetic effect in the micellization process of the TX-100 and CTAB mixtures was also found. The highest synergetic effect appeared at the mole fraction of TX-100 in the mixture with CTAB in the bulk phase equal to 0.8. For such TX-100 and CTAB mixture the mole fraction of sur-factants in the bulk phase was comparable to that in the micelles.At the mole fraction of TX-100 in the bulk phase lower than 0.8 the big increase of its mole fraction in the micelles takes place. The mole fraction of CTAB and TX-100 in the micelles depends also on the concentration of ethanol. It is interesting that the tendency of CTAB to adsorb at the water-air interface is lower than that to form mixed micelles with TX-100. Unexpectedly, the increase of the TX-100 concentration causes the increase of the conductivity of the solution at the same CTAB concentration but only in the range of ethanol concentration in which it is present in the monomeric for min the solution.
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