Equilibrium, kinetics and thermodynamics of Pb (II) ions from aqueous solution by adsorption onto chitosan-dolomite composite beads

Abstract

This paper aims to investigate the adsorption process of a new composite adsorbent prepared from chitosan (Ch) and dolomite (Do) for removal of lead ions from aqueous solutions. The adsorp-tion process of Pb2+ions onto Ch-Do composite adsorbent as initial Pb2+ concentration, solution pH, temperature, contact time and desorption was investigated. From the results, it has been observed that the highest removal efficiency is approximately 89% at contact time of 6 h, initial Pb2+concentration of 500 mg L−1, adsorbent dosage of 100 mg and agitation speed of 150 rpm at pH 4.0. Langmuir isotherm has a better fit with the experimental isotherm data (R2 = 0.920). The maximum Pb2+adsorption capacity from the Langmuir model was found as 0.332 mol kg−1 at 25°C Also, it per-forms pseudo-second-order superior performance in kinetic beha-viour compared to other used kinetic models (R2 = 0.904). Thermodynamic parameters showed the Pb2+adsorption onto Ch- Do was endothermic, spontaneous and possible. The desorption studies have shown that Ch-Do composite adsorbent has a good adsorption/desorption performance for Pb2+ions.