Influence of pH and Ionic Strength on Equilibrium Sorption of Cationic Dyes by Acrylic Fibers

We have investigated the equilibrium sorption of two cationic dyes by acrylic fibers at different pH levels and sodium chloride concentrations. To interpret the data, we used the simple Donnan approach with the assumption that the acrylic fibers contained two different types of acidic groups. The distribution coefficients of the dyes are dis cussed in relation to the structures of the dyes and the fibers and the effect of sodium chloride. The equilibrium sorption at different pH levels gives some indication of the strength of the strongly and weakly acidic groups of the acrylic fibers not directly accessible by experiments.