Dye adsorption of cotton fabric grafted with PPI dendrimers: Isotherm and kinetic studies

• In this work, dye adsorption of cotton grafted with PPI dendrimers has been studied.
• It is found that the dye adsorption of the grafted fabric is strongly pH dependent.
• Maximum adsorption capacity was determined using the Langmuir isotherm.
• Pseudo-second order model has a good agreement with the experimental kinetic data.

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.