Evaluation of adsorption efficiency of activated carbon/chitosan composite for removal of Cr (VI) and Cd (II) from single and bi-solute dilute solution

The aim of this study was to evaluate the adsorption capacity of the novel coated activated carbon by chitosan for removal of Cr (VI) and Cd (II) ions from single and bi-solute dilute aqueous solutions. In addition, the adsorption abilities of activated carbon (AC), chitosan (CH) and chitosan / activated carbon composite (CHAC) have been compared. Adsorption studies were performed in a batch system, and the effects of various operating parameters such as solution pH, particle size and the dose of adsorbent were considered for removal of Cr (VI) and Cd (II) by Taguchi method. Equilibrium experimental data were well fitted to Langmuir isotherm for single and bi-solute solutions. The adsorption capacities of AC and CH adsorbents have improved by synthesis CHAC composite. As it was expected, competitive adsorption of metal ions on the CHAC surface led to reducing the adsorption capacity from 90.9 mg g-1 to 41.94 mg g-1 for Cr (VI) and 52.63 mg g-1 to 30.21 mg g-1 for Cd (II) ions, respectively. The adsorption capacities for the metal solution–adsorbent systems are in the order Cr (VI) > Cd (II). The kinetic studies indicated that the adsorption process was best described by the pseudo-second-order kinetics for single and bi-solute solutions.