Removal of Pb(II) and Cd(II) heavy metals from aqueous solution by FeNi 3 @MnO 2 core–shell nanostructure

In this article, FeNi3@MnO2 core–shell nanostructure has been used for the first time to remove Pb(II) and Cd(II) from aqueous solutions by adsorption. The MnO2-coated FeNi3 magnetic nanoparticles were synthesized by the hydrothermal method and characterized by various analytic methods such as X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscope, transmission electron microscope, and atomic absorption spectrometry. Adsorption parameters such as pH, contact time, adsorbent amount, and initial concentration of metal ions were investigated and optimized. FTIR Spectrum of the nanostructure was used to analyze the adsorption mechanism. FeNi3@MnO2 adsorbent was shown to follow the Langmuir adsorption isotherm and the pseudo-second-order kinetic model. The thermodynamics of adsorption confirmed an endothermic and spontaneous process. The calculated maximum adsorption capacities of the adsorbent for Pb(II) and Cd(II) were 129.2 mg g−1 and 127.8 mg g−1 at room temperature, which confirmed a good adsorption performance, especially for Cd(II). The adsorbent had a good removal efficiency of more than 99% for both metal ions, which was achieved in only 20 minutes.