Combined UV-Vis-absorbance and Reflectance Spectroscopy Study of Dye Transfer Kinetics in Aqueous Mixtures of Surfactants

We report an analytical approach to study the kinetics of desorption and exhaustion of a hydrophobic dye in a multicomponent washing model environment. The process of dye transfer between an acceptor textile (white polyamide), detergent micelles and a donor textile (red polyester) was quantified by a combination of colorimetric analyses. UV-Vis absorbance and UV- reflectance spectroscopy were used to follow the concentration of the solubilised dye in the micelles and the amount of dyer transferred to the acceptor textile, respectively, as a function of time. Up to ≃ 10 min of the washing process, the released dye is predominantly solubilised in surfactant micelles. At later times, the adsorption of the dye on the hydrophobic surface of the acceptor textile is energetically favoured. The shift of the desorption equilibrium in the presence of the acceptor textile results in ≃ 30% increase in the release of the dye. The reported methodology provides insight into the competition between solubilisation of hydrophobic molecules by amphiphiles and dye adsorption on solid substrates, important for designing novel concepts of dye transfer inhibition.