Adsorption kinetics of some textile dyes onto granular activated carbon

Adsorption kinetics of Acid Blue 113 (AB), Basic Red 5 (BR) and Reactive Yellow 81 (RY) textile dyes were studied. The investigations were essentially conducted to determine the influence of the initial dye concentration of aqueous solutions on the adsorption kinetics. The experiments, carried out in a batch reactor, allowed the determination of the equilibrium times (≤1 h for RY and AB and ≈4 h for BR). The experimental data were analyzed according to the surface reaction and intra-particle models. In effect, the adsorption results were perfectly fitted to the pseudo-second order, with very high regression coefficients (r2), predicting a significant intra-particle diffusion stage in the controlling of the adsorption process. Moreover, the fitting to Elovich equation, confirms that the process is ensured by chemisorption on a highly heterogeneous material.