Kinetic studies on the removal of Reactive Blue 49 dye from aqueous solution onto chitosan-activated sludge composite particles

Abstract

Nowadays, water contamination due to the textile dyeing residues is increasing and alarming. One of the most important decontamination techniques is considered to be adsorption due to its efficiency and low cost. Numerous adsorbent materials are prepared the last years to remove toxic dyes especially from contaminated waters. In this study, waste activated sludge produced in biological treatment systems were evaluated and the composites containing chitosan and the waste sludge were synthesized as an adsorbent. The adsorption characteristics of Reactive Blue 49 (RB49) from aqueous solution onto the chitosan-activated sludge composites have been investigated. The effects of contact time and solution pH for the adsorption of RB49 by the chitosan-activated composites was studied for a period of 27 h for initial dye concentrations of 60 mg/l at 25°C. The maximum adsorption capacities of the composites was 16.91 mg/g and obtained at pH 1. Three kinetic models (pseudo first order, pseudo-second order and intraparticle diffusion model) are employed to fit the experimental data and to elaborate the kinetic mechanism for the adsorption of RB49 on the chitosan-activated sludge composites. The pseudo-second-order kinetic model provided the best fit to the experimental data for the adsorption of RB49 dye. Overall, this study indicates the chitosan-activated sludge composites as an effective adsorbent for the removal of RB49 dye from the aqueous solutions. The usage of the composites as adsorbent in adsorption process can manage the environment and turn waste into treasure.