Immobilization of residual dyes onto ion-exchanger cellulosic materials

This article reports on the preparation of cationized cotton fiber by treating alkali cellulose cotton fibers with epoxy propyltrimethylammonium chloride (EPTMAC) in a nonaqueous medium and its use as support for the immobilization of pollutant dyes. Evidence of attaching quaternary ammonium groups onto cellulose is provided by IR analysis, nitrogen determination, and weight uptake. Four EPTMAC-Cotton fiber samples with different nitrogen content (0.5-1.85) are tested for the adsorption of four acid dyes (Acid Blue 25, Acid Yellow 99, Reactive Yellow 23, and Acid Blue 74). Adsorption is followed spectrometrically, the capacity of adsorption depending on the nitrogen content and on the number of anionic groups in the dye. The Langmuir and Freundlich isotherms constants are evaluated from the experimental data, but better agreement is obtained by using a composite isotherm of the general form Y e = iC e /(1 + jC e m ), where i, j, and m are constants.