Effect of Ethyl Xanthogenate on the Absorption of a Cationic Dye on Polyester Fibers: Zeta Potential and Sorption Thermodynamics

Data are presented for the zeta potential, kinetics, and sorption thermodynamics of CI Brilliant Green on both untreated polyester fibers and polyester pretreated with constant amounts of potassium ethyl xanthogenate at different temperatures. The rising temperature of the system increases dye absorption on untreated polyester, and the rising temperature of absorption increases dye uptake on pretreated polyester. Cationic dye absorption is enhanced by increasing amounts of ethyl xanthogenate taken up by the fibers during pretreatment. The negative zeta potential of pretreated polyester rises when the amount of ethyl xanthogenate in the pretreatment is increased at low concentrations of dye solution. The zeta potential sign changes at high con centrations of cationic dye in the liquid phase. When the amount of ethyl xanthogenate in the pretreatment increases, there is a displacement of this sign inversion toward lesser concentrations. Absorption equilibria, empirical rate constants, activation energy, standard affinity, and enthalpy and entropy of reaction are determined for cationic dye absorption on untreated and pretreated polyester. The results and the molecular structure of the dye and ethyl xanthogenate suggest that the absorption of CI Brilliant Green on the pretreated polyester probably takes place by means of an electrostatic attraction between the dye cation and the negatively charged -S ^- groups of the ethyl xanthogenate.