Effective removal of lead(ii) from wastewater by amine-functionalized magnesium ferrite nanoparticles

Abstract

Mesoporous amine-functionalized magnesium ferrite nanoparticles (MgFe₂O₄–NH₂ NPs), with maximum magnetization of around 35 emu g⁻¹, were successfully synthesized and simultaneously functionalized under a refluxing condition by using ethanolamine as a surface modifier. The grafting of amine groups onto the MgFe₂O₄ NPs was clearly confirmed by the Fourier transform infrared spectrum. Adopting the MgFe₂O₄–NH₂ NPs as a magnetic nanoadsorbent for Pb²⁺ removal from simulated wastewater containing heavy metals is reported. Characterizations of the adsorption ability of MgFe₂O₄–NH₂ nanoadsorbent as a function of aqueous solution pH, initial Pb²⁺ concentration and agitating time, as well as their adsorption kinetics and adsorption isotherms, were also performed. The adsorption of 25 mL of 10 mg L⁻¹ Pb²⁺ initial concentration onto 25 mg of MgFe₂O₄–NH₂ nanoadsorbent reached equilibrium within 10 min at pH 4 with 99% removal efficiency. Kinetics and isotherms of the adsorption were fitted with pseudo-second-order model and Langmuir model, respectively, indicating the strong chemisorption through coordinative bond formation between the amine groups and Pb²⁺ ions. This MgFe₂O₄–NH₂ nanoadsorbent possesses a maximum capacity, calculated from Langmuir equation, of around 135.1 mg g⁻¹, which is higher than those of typical amine-functionalized adsorbents. Also, the selectivity experiments show that the MgFe₂O₄–NH₂ nanoadsorbent provides higher selectivity coefficient values for Pb²⁺ than Ca²⁺, Cd²⁺, Zn²⁺, Cu²⁺ and Ni²⁺.