Recyclable functionalized polyethyleneimine-coated magnetic nanoparticles for efficient removal of lead from aqueous solutions

Abstract

Background: Lead is among the most lethal heavy metals, displaying toxicity towards humans, animals and plants. Removal of lead ions from wastewater prior to its disposal is very important. Consequently, the development of adsorbents which can effectively remove Pb(II) from water is a subject of growing research interest. Results: Polyethyleneimine-coated magnetic nanoparticles functionalized with various compounds, namely salicylaldehyde, carbon disulfide and o-vanillin, were synthesized and employed in the removal of Pb(II) from aqueous solutions. These com-pounds act as chelating agents which bind to toxic metal ions to form complex structures which are easily removed from the solutions. A very effective uptake of Pb(II) (98.1% of 25 mg L−1 Pb(II)) was achieved with an adsorbent dose of 10 mg, a contact time of 60 min and at a pH of 6.5. Equilibrium data for isothermal, kinetic and thermodynamic studies indicate that the process of adsorption fitted well with the Langmuir adsorption isotherm model. The kinetics of adsorption proceeded through apseudo-second-order rate while the thermodynamic parameters indicated that the process was spontaneous and endothermic. Conclusion: Functionalization of iron oxide nanoparticles was confirmed by various techniques. Adsorption factors were optimized in order to achieve maximum removal of Pb(II). The modified magnetic materials are highly effective active sorbent materials. The hydroxyl, thiol and thiocarbamate groups have a synergistic effect on Pb 2+ removal through electrostatic inter-actions and chelation. Adsorption studies demonstrate that a high adsorption capacity (92%) was achieved within 10 min at25 °C using the adsorbent MNP@PEI-CS2 . The nanoadsorbents can be reused without affecting their removal capacity.