EFFECT OF ETHYL XANTHOGENATE ON SORPTION OF AN ACID DYE ON POLYESTER FIBERS .1. ELECTROKINETIC PROPERTIES

An investigation of the streaming potential, sorption, and electrical conductance of a porous plug of polyester fibers treated with ethyl xanthogenate and afterwards dyed with the acid dye Sirius red 4B at varying temperatures is described. The zeta potential of the polyester/potassium ethyl xanthogenate system is negative in the whole range of concentrations studied (10(-6) to 10(-2) mole/liter), and the absolute value of this parameter increases when the temperature of the system is increased. Uptake of ethyl xanthogenate on the polyester in the temperature interval tested is improved by the increased temperature. These results reveal that uptake occurs with the establishment of strong chemical bonds. The zeta potential of the fiber/dye solution system is negative in the range of concentrations studied, and the absolute value of the system's zeta potential decreases markedly when the temperature increases. Dye adsorption on polyester decreases when the adsorption temperature increases, suggesting that dye adsorption on polyester in the temperature interval tested takes place without the establishment of strong chemical bonds. The absolute value of the system's negative zeta potential decreases markedly when the amount of ethyl xanthogenate previously taken up by the fiber increases at constant temperature. Dye uptake by the pretreated polyester improves with increasing amounts of ethyl xanthogenate taken up by the fiber and with increased sorption temperature, suggesting that dye uptake with this system takes place with the establishment of strong chemical bonds. On the basis of the molecular structure of these compounds, dye uptake probably takes place by means of a nucleophilic attack of the -S- group of the ethyl xanthogenate on the carbonyl group of Sirius red 4B. The electrical conductance of the system increases with both increasing dye concentration in solution and increased sorption temperature which agrees with the hypothesis of strong chemical bonds involved in this process.