3D hierarchical flower-like nickel ferrite/manganese dioxide toward lead (II) removal from aqueous water

A functionalized magnetic nickel ferrite/manganese dioxide (NiFe 2 O 4 /MnO 2 ) with 3D hierarchical flower-like and core–shell structure was synthesized by a facile hydrothermal approach and applied for the removal of Pb(II) ions from aqueous solutions. Batch adsorption experiments were conducted to study the effect of solution pH, initial Pb(II) concentration, and dose of absorbents on the Pb(II) removal by NiFe 2 O 4 /MnO 2 . The NiFe 2 O 4 /MnO 2 nanocomposites showed the fast Pb(II) adsorption performance with the maximum adsorption capacity of 85.78   mg   g −1 . The adsorption kinetics of Pb(II) onto NiFe 2 O 4 /MnO 2 obeyed a pseudo-second-order model. The isothermal experimental results indicated that the Langmuir model was fitted better than the Freundlich model, illustrating a monolayer adsorption process for Pb(II) onto NiFe 2 O 4 /MnO 2 . Meanwhile, the NiFe 2 O 4 /MnO 2 was easily separated from the solution by an external magnet within a short period of time and still exhibited almost 80% removal capacity after six regenerations. The NiFe 2 O 4 /MnO 2 is expected to be a new promising adsorbent for heavy metal removal.