Physical Chemistry of Dyeing of Cellulosic Fibers with Reactive Dyes

Abstract

The effect of different electrolytes on the sorption of the hydrolyzed form of four different reactive dyes has been investigated. The electrolytes studied were sodium, ammonium, Jithium, and magnesium chlorides, and ammonium sulfate, which differ widely in their ability to increase the sorption of hydrolyzed reactive dyes by cellulose. Their relative efficiencies were in the order: ammonium chloride > ammonium sulfate > sodium chloride > lithium chloride ~ magnesium chloride. The effect of the electrolytes has been discussed in terms of partial screening of the surface charge on cellulose by the crowding of the cations at the cellulose-water interface, pH of the bath, and the ability to modify the structure of water. The ability of the electrolytes to modify the pH of the solution plays a dominant role in sorption increase at lower con centrations of electrolytes, whereas at higher concentrations the ability of the electrolytes to modify the cellulose-water interface plays a decisive role.