Comprehensive Study of Tartrazine/Cationic Surfactant Interaction

Abstract

Interaction of a food dye, tartrazine, with some cationic conventional and gemini surfactants, tetradecyltrimethylammonium bromide (TTAB), N,N'-ditetradecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (14,4,14), and N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (12,4,12), were first investigated comprehensively employing conductometry, tensiometry, and UV-visible spectroscopy. Tartrazine was found to behave in the same manner as aromatic counterions. The formation of ion pairs reflected as a considerable increase of the surfactant efficiency in tensiometry plots and their stoichiometry were determined by Job's method of continuous variations. For the tartrazine/TTAB system, nonionic DS(3), ionic DS(2-), and/or DS(2)(-) ion pairs, their small premicelles, and tartrazine-rich micelles were constituted as well as dye-containing TTAB-rich micelles. Insoluble J-aggregates of DS(-) ion pairs and cylindrical surfactant-rich micelles were also formed in tartrazine/gemini surfactant systems and recognized by transmission electron microscopy. The zeta potential and the size of the aggregates were determined using dynamic light scattering and confirmed the suggested models for the processes happening in each system. Cyclic voltammetry was applied successfully to track all of these species using tartrazine's own reduction peak current for the first time.

Modifying Effect of Imidazolium-Based Ionic Liquids on Surface Activity and Self-Assembled Nanostructures of Sodium Dodecyl Sulfate

“…On the other hand, contribution of Crystal Violet into SDS micelles results in the partial red shift of λ max from 590 to 595 nm (plot has been provided as Supporting Information). The spectral changes of dye molecules in the presence of oppositely charged micelles have been suggested to be caused by the electrostatic interaction between oppositely charged molecules, formation of molecular complexes with oppositely charged micelles, and changes in the microenvironment of dye chromophore. , Ghanadzadeh et al have reported a blue shift in λ max of Crystal Violet through the reduction of solvent polarity . We also recorded a λ max of 587.73 nm for 6.17 × 10 –2 mM solution of Crystal Violet in ethanol.…”

“…At this point the surface is saturated with ion pairs and further addition of SDS results in the aggregation of ion pairs in the form of dye–surfactant premicelles or dye-rich micelles . Our previous studies on some similar dye/surfactant systems showed these ion pair premicelles or dye-rich micelles are then transformed into surfactant micelles with solubilized dye molecules as the concentration of surfactant reaches the CMC of pure surfactant. , Therefore, further addition of SDS beyond the minimum point results in solubilization of SDS–dye ion pairs into premicelles and micelles, which is reflected as the increase of absorbance ratio up to its initial value for pure Crystal Violet solution (spectrum no. 3 in Figure ).…”

Ion Pairing and Adsorption of Azo Dye/C16TAB Surfactants at the Air–Water Interface

“…However, independent of the exact nature of the formed structures after the ionic azo dye interacts with the ionic surfactant, it was concluded that the dramatic changes in UV/vis spectra and in particular of the absorption band at a wavelength of 480 nm can only be only due to complex or ion pair formation. ,, That is because such substantial changes demand strong electrostatic interactions. For that reason, we attribute the decrease of the absorbance band to the formation of SSY/C 16 TAB ion pairs and the plateau in Figure b at SSY: C 16 TAB molar ratios >1:2 to a 1:2 stoichiometry of anionic SSY and cationic C 16 TA + ions ([SSY] 2– [C 16 TA + ] 2 ).…”

“…Job’s plots have been used in previous work for the investigation of dye-surfactant binding interactions. 6 , 38 − 41 For a description of the working principle and experimental results from the application of the Jobs method the reader is referred to the Supporting Information .…”

“…The method of continuous variations, also known as Job’s plot (details in the Supporting Information), was applied in order to resolve the stoichiometry of ion pair formation between SSY and C 16 TAB. Job’s plots have been used in previous work for the investigation of dye-surfactant binding interactions. ,− For a description of the working principle and experimental results from the application of the Jobs method the reader is referred to the Supporting Information.…”