Interaction between zwitterionic sultaine derived from waste edible oil and methyl orange in mixed solvents: Solvent...

The interaction behavior between methyl orange (MO) and zwitterionic surfactant fatty amidopropyl hydroxysulfobetaine (FSB) derived from waste edible oil in three solutions including water, water-glycerol (0.10 mol/L) and water-glycol (0.10 mol/L) is investigated using the UV-vis spectrometry at 298.15 K. Upon adding solvent (glycerol or glycol), the absorption spectra of MO show some distinct differences in the intensity of peak and the wavelength of maximum absorption (λ_max) in absence and presence of FSB. Absorption band of MO depends largely on the surfactant concentration. In diluted surfactant solutions, the peak decreases and the λ_max moves slightly toward the short wavelength with adding FSB. In micelle solutions, while, the peak enhances and the red shift of λ_max appears with increasing the FSB concentration. The change of the nature of mixed solvent results in different contributions from some effects including the electrostatic interaction, the hydrophobic effect, etc. and then induces the differences in the interaction between MO and FSB and the partition of MO in micelle. The association constants based on two models including both in the micelle solution and in the premicelle and micelle solution and the partition coefficients further describe the molecular interaction behavior. These values from free energy changes imply that the addition of glycerol in solution facilitates the association or partition spontaneous process. These findings will help with understanding the interaction of dye and surfactant and the solvent effect and further obtaining some information about the application of dye in many fields.