Micellization of Pentanediyl-1,5-bis(hydroxyethylmethyl hexadecylammonium Bromide) as a Cationic Gemini Surfactant in Aqueous Solutions: Investigation Using Conductometry and Fluorescence Techniques

Adsorption and volumetric properties of some nonionic surfactants and their mixtures with quercetin and rutin

The adsorption and volumetric properties of the Triton X-114 (TX114), Tween 80 (T80), quercetin (Q) and rutin (Ru) at the different temperatures in relation to above properties of the TX114 and T80 mixtures with quercetin and rutin in the absence and presence of alcohol were discussed based on the studies reported in the literature. The adsorption isotherms of the mixtures of the nonionic surfactants with flavonoids in the presence and absence of alcohol were analyzed based on the isotherms of the surface tension of the particular mixture components and thermodynamic parameters of the adsorption of these components at the water-air interface. The surface tension isotherms of the particular component of the mixtures were taken into account while considering the surface tension isotherms of the mixtures and the composition of the mixed surface layer at the water-air interface. Different ways of the mixed surface layer composition determination were shown. The values of the surface tension and composition of the mixed surface layers obtained using different methods were discussed in the light of the intermolecular interactions and their contribution to the surface tension of the surfactants mixture with flavonoids and alcohol. The composition of the mixed monolayer and the bulk phase were compared and the differences between them were explained. The behaviour of the nonionic surfactants and flavonoids in the presence and absence of alcohol was analyzed in relation to the micelle formations and molar volumes of the mixtures and their components. Moreover, the micelles composition and their size as well as the thermodynamic parameters of the micellization process were analyzed.

Thermodynamic and Interfacial Properties of Cationic Gemini Surfactant in the Presence of Alcohols

The micellar properties of the cationic Gemini surfactant ethanediyl-1,2-bis(dimethyldodecyl ammonium bromide), C12H25 · (CH3)2N+–(CH2)2–N+(CH3)2C12H25 · 2Br− (12-2-12), with short chain alcohols have been studied by conductivity and surface tension measurements within the temperature range 293.15 K–313.15 K and alcohol percentage. The critical micelle concentration (CMC) of 12-2-12 solution, degree of ionization (α) and standard Gibbs free energy of micellization (ΔG°m), standard enthalpy of micellization (ΔH°m) were calculated from conductivity and surface tension data. The experimental data show that the CMC values of cationic Gemini surfactants increased with addition of methanol, ethanol and n-propanol. The thermodynamic parameters (ΔG°m), (ΔH°m) and (ΔS°m) of micellization of 12-2-12 in alcohol were also calculated from the temperature dependence of the CMC values. CMC, (α), (ΔH°m) and (ΔS°m) increased linearly with increasing temperature. In the mixture of dimeric cationic surfactant (12-2-12) and alcohol solutions, the CMC values showed a slight increase with increasing alcohol concentration. CMC, maximum surface excess concentration at the solution/air interface, Γmax, minimum area per surfactant molecule, Amin, and the surface pressure at CMC, ¶CMC, values calculated from the surface tension measurements and thermodynamic parameters have been evaluated at same temperatures.