Removal of Pb2+ ions from aqueous medium by using chitosan-diatomite composite: equilibrium, kinetic and thermodynamic studies

Abstract: In this study, a novel, low-cost, natural, and highly effective adsorbent, chitosan (Ch) -diatomite (D) composite was synthesized. Ch-D composite was tested as an effective and alternative adsorbent for the removal of Pb 2+ ions. The Ch-D composite was characterized by FT-IR, SEM-EDX and PZC analyses. The adsorption  process of Pb 2+ ions onto Ch-D as initial lead concentration, s olution pH, temperature, contact time and recovery was investigated . From the adsorption process results, it has been observed that the highest removal efficiency is approximately 95% at a contact time of 4-hour, initial Pb 2+ concentration of 500 mg L -1 and agitation speed of 150 rpm at natural pH 4.0. The maximum Pb 2+ adsorption capacity from the Langmuir model was f ound as 0.154 mol kg -1 at 25 o C. Besides, adsorption kinetics was also explained with pseudo-first-order models. Adsorption thermodynamics have shown that Pb 2+ adsorption onto Ch-D is possible, spontaneous and exothermic. Ch-D composite can become an alternative adsorbent for the treatment of lead ions in the wastewater.