Interaction of Polymer (Polyvinylpyrrolidone) with Azo Dye (Reactive Yellow): A Physicochemical Study

The influence of polymer, polyvinylpyrrolidone (PVP) on spectral properties of anionic azo dye, reactive yellow (RY) was investigated by UV–Vis spectroscopy in the temperature range of 298–313 K. The change in λmax and absorbance indicated the presence of interaction between anionic dyes and polymer. The binding constant (Kb) of complexation was determined from the Benesi–Hildebrand plot. The Kb value increased with increasing dye concentrations and decreased with the rise of the temperature. The values of ∆G° for RY–PVP complexation were found to be negative and these negative values reduce with the enhancement of temperature which indicates that the binding process is more spontaneous at lower temperature. The negative values of ΔS° and negative values of ΔH° refer a process which is always enthalpy dominated. Kb values showed significant change with the change of pH. The Kb value enhances with the rise of the carbon chain length of the alcohol and reduces with increasing percentages of alcohol. The Kb value decreases at higher electrolyte concentrations and also with the increase of the size of the anion of the electrolyte. The removal of dye from the waste water by the interaction of dye with polymer in the presence of surfactant and salt of higher concentration has also been studied.