Adsorption of lead (ii) ions on magnetite/magnesium oxide nanocomposites

Abstract

The effective removal of heavy metal ions, particularly lead(II) [Pb(II)], from contaminated water sources remains a pressing environmental concern. This study explores the potential of magnetite/magnesium oxide (Fe₃O₄/MgO) nanocomposites as an efficient adsorbent for selective Pb(II) removal. The Fe₃O₄/MgO nanocomposites were synthesised using a controlled sol-gel method and characterised using various techniques. XRD analysis confirmed the presence of cubic MgO and cubic Fe₃O₄. Pb(II) adsorption induced a crystallographic transformation, forming hexagonal Mg(OH)2 crystals, indicating interaction with the adsorbent. SEM analysis revealed rod-like and spongy spherical morphologies. Rod-like structures provided a larger surface area and active sites for effective Pb(II) interaction, while spongy spherical particles, representing magnetic Fe3O4, contributed to stability and dispersibility. EDS analysis showed Fe, O, and Mg presence with weight percentages of 28.97%, 25.55%, and 30.0%, respectively. VSM results confirmed superparamagnetic behavior with a saturation magnetisation of 32.02 emu g⁻¹, indicating potential for magnetic separation and recovery in various wastewater treatment applications. Adsorption experiments utilised optimised conditions: initial concentration of 600 mg L⁻¹ adsorbent dosage of 0.25 g L⁻¹, pH of 7, and 120 minutes reaction time. Fe₃O₄/MgO nanocomposites exhibited exceptional performance with a remarkable 99.98% removal efficiency and a high adsorption capacity of 2399.44 mg g⁻¹. These impressive results underscore the outstanding adsorption potential of the nanocomposites. Adsorption kinetics followed the pseudo-second-order model (R2 = 0.99), confirming suitability for Pb(II) removal. The Freundlich model indicated a heterogeneous surface with different adsorption sites. These comprehensive findings support efficient Pb(II) removal using Fe₃O₄/MgO nanocomposites, paving the way for advanced adsorption strategies in water treatment. Overall, Fe₃O₄/MgO nanocomposites exhibit potential as a cost-effective, environmentally friendly adsorbent for removing Pb(II) ions, providing a promising water purification and environmental remediation solution.