Facile synthesis of core-shell magnetic Fe3O4@SiO2-NH2 nanoparticles and their application for rapid boron removal from aqueous solution

Abstract

Abstract Amino-functionalized magnetic particles (Fe3O4@SiO2-NH2) with core-shell structure were synthesized and evaluated for rapid boron removal from aqueous solution. Results showed that the specific surface area of Fe3O4@SiO2-NH2 (165.17 m2⋅g− 1) increased greatly compared to the pure Fe3O4 (49.07 m2⋅g− 1). The adsorption equilibrium was less than 2 h with an adsorption capacity of 29.76 mg⋅g− 1at pH = 6 of 15°C. The quasi second-order kinetic model described well the boron adsorption process and the Freundlich model was more suitable for characterizing the adsorption isotherms. Furthermore, the negative value of Gibbs free energy indicated that the adsorption was spontaneous and an exothermic process. The zeta potential and XPS analysis before and after adsorption revealed that the main adsorption mechanism was the hydrogen bonding formation between the terminal –NH2 groups of the adsorbent and the boric acid. In addition, the adsorbent still maintained a high adsorption performance after five adsorption-desorption cycles, which illustrated that the Fe3O4@SiO2-NH2 may be a potential adsorbent for the environmental boron removal treatment.