Spectroscopic, thermodynamic and kinetic prediction models of dye mixtures in aqueous solutions

The purpose of the research has been to develop mathematical models to predict concentration and dyeing rates for individual dyes and mixtures of dyes. The dyes studied were analyzed using spectroscopic and surface tension measurements, then the dyeing properties were determined by exhausting the dyes onto cotton fabric individually and in mixtures. Fixation of the dye to the substrate was not examined. Using a real-time data acquisition system, pH, temperature, conductivity, and absorbance across the visible spectrum was measured every ten seconds. Dye concentrations were predicted using constants derived by individual regression, multiple regression and Neural Network models. Kinetic properties were predicted using a limiting equation and an exponential model based on the Langmuir Isotherm. The non-additive spectra of the dye mixtures was described quantitatively and qualitatively as a concentration dependent function of the dye-dye interaction. Deviations from rate constants were likewise described by the extent of dye-dye interaction and the concentration of the interacting species. The state of the dye molecule in solution was determined to be an important factor in the spectroscopic measurement and the kinetic properties of dyeing with monochlorotriazine reactive dyes under industrial conditions.