Spectral Study of Aggregation Behavior of Remazol Brilliant Violet-5r Dye in Cationic Ligand Solutions

An UV-VIS spectrophotometric investigation has been made to study the interaction and aggregation of anionic remazol brilliant violet-5R (RBV-5R) dye in acidic ethanol amine and tallow amine solutions. As a consequence of increasing the concentration of ethanol amine, the maximum absorbance spectra was shifted to higher energy (blue shift) with increasing in the intensity and a new band with a maximum peak at 420 nm (H-band) was appeared, which is as a result of formation of new complex (dye-ethanolamine) or dye-dye aggregation (H-Aggregate). This was an evidence of aggregation by London dispersion and hydrophobic forces attraction. The binding constant, Kb, was determined using the modified Benesi–Hildebrand Equation and the standard free energy change ΔG◦ was found -12.13 kJmol-1. By addition of acidic tallow amine solution to the dye, the changes in spectral features were recorded above the critical micelle concentrations. Spectra of aggregated dye molecules due to incorporated in micelles are increases with addition of tallow amine surfactants. It is shown that electrostatic interactions play a key role in dye binding to micelles. The surfactant micelle, which has a longer alkyl hydrocarbon chain, enables greater solubilization of dye. Thus, the hydrophobic interaction of the dye with micelles increases.