A novel magnetic chitosan/clinoptilolite/magnetite nanocomposite for highly efficient removal of Pb(II) ions from aqueous solution

A novel nanocomposite (with components of chitosan, clinoptilolite and magnetite) was synthesized featuring magnetic properties, and was used for the removal of Pb(II) as a toxic heavy metal from aqueous solutions. The effects of temperature, contact time, Pb(II) concentration, pH value of the solution and adsorbent dosage on the adsorption capacity of the nanocomposite were investigated. The kinetics data of adsorption process were analyzed by the models of pseudo-first order, pseudo-second order, the Elovich and intra-particle diffusion. The adsorption kinetics was well described by the pseudo-second order equation. The adsorption isotherms were more accurately fitted by the Langmuir equation and the maximum theoretical Pb(II) adsorption capacity of the nanocomposite was found to be 136.99 mg/g at pH 6 and 333 K. The negative Gibbs free energy values of adsorption illustrated the spontaneity of the adsorption of Pb(II) ions on the nanocomposite. The magnetic nanocomposite gave a saturation magnetization value of 9.50 emu/g, therefore, it was efficiently separated from the solution by a fast and simple magnetic separation process. Desorption of the Pb(II) ions from the nanocomposite was achieved by using 0.01 M HNO3, CaCl2 and NaCl solutions. The prepared nanocomposite exhibited proper magnetic property, high thermal strength and large specific surface area while being synthesized at low cost. Hence, it offers possibilities for future practical use. (C) 2016 Elsevier B.V. All rights reserved.