Removal of Ni(II) and Zn(II) from Aqueous Solutions Using Chitosan

Background & Aims of the Study: The increasing levels of toxic heavy metals dischargedinto the environment have received considerable attention due to the adverse effects onreceiving waters. Therefore, the developed adsorbent was assessed for its practical role inremoval of metal ions from industrial wastewater. The purpose of the present work is toinvestigate the removal of Ni(II) and Zn(II) ions by chitosan as an abundant andinexpensive adsorbent.Materials & Methods: In this study, adsorption of metal cations onto this new adsorbentwas studied in terms of pH (2.0-9.0), adsorbent dose (1.0-7.0 g), contact time (15-120 min)and initial dye concentration (100-800 mg.L-1) in batch mode. The experimental data werefitted with different isotherms and kinetics models.Results: The results demonstrated that the optimum pH was found to be 5.0 and 6.0 forNi(II) and Zn(II) and the equilibrium was achieved after 75 and 60 min for Ni(II) andZn(II) adsorption, respectively. Evaluation of the experimental equilibrium data byLangmuir and Freundlich isotherm illustrated that Langmuir is superior to other model forfitting the experimental data in term of higher correlation coefficient. The results ofexamination of the time on experimental adsorption data and fitting the data toconventional kinetic model show the suitability of pseudo-second order model. Themaximum predicted adsorption capacities for Ni(II) and Zn(II) ions were obtained as 52.6and 45.4 mg.g−1, respectively.Conclusions: The results indicate that the chitosan is one of the best adsorbents for theremoval of metal cations from aqueous solution.