Preparation of amino-functionalized CoFe2O4@SiO2 magnetic nanocomposites for potential application in absorbing heavy metal ions

Abstract

Amino-functionalized nanocomposites with a magnetic CoFe₂O₄ core and an amorphous SiO₂ shell have been designed and synthesized. The core–shell structure was characterized by SEM, EDS, TEM, FTIR and XPS. CoFe₂O₄@SiO₂–NH₂ with a high saturated magnetization (28.09 emu g⁻¹) can be easily separated under a moderate external magnetic field within one minute. In addition, the adsorption capacity of the CoFe₂O₄@SiO₂–NH₂ for Cu(II), Cd(II) and Mn(II) was 170.829, 144.948 and 110.803 mg g⁻¹, respectively. The removal efficiency was increased from 12 to 85% with an increase in the pH from 4 to 6.5. The adsorbent can be recycled for at least four cycles with a feasible removal efficiency (85.41%). The adsorption process was fitted by pseudo-second-order kinetics and a Langmuir isotherm model. Based on the data of the present investigation, CoFe₂O₄@SiO₂–NH₂ could find potential applications in heavy metal ion wastewater treatment.