In this research, the cotton fabrics grafted with two generations of the poly(propylene imine) dendrimers
were applied to adsorb textile dyes from aqueous solutions. Direct Red 80 (anionic dye), Disperse Yellow
42 (nonionic dye) and Basic Blue 9 (cationic dye) were selected as model dyes. The effect of various
experimental parameters such as initial concentration of dyes, charge of dyes molecule, salt and pH was
investigated on the adsorption process. Furthermore, kinetics and equilibrium of the adsorption process
on the grafted samples were studied. It was found that maximum adsorption of anionic and disperse
dyes took place at around pH 3, while cationic dye could be adsorbed at around pH 11. The Langmuir
equation was able to describe the mechanism of dyes adsorption. In addition, the second-order equation
was found to be fit with the kinetics data. Interestingly, it seems that the dye adsorption of the grafted
fabrics is strongly pH dependent.