Facile Synthesis of Polypyrrole-Functionalized CoFe₂O₄@SiO₂ for Removal for Hg(II).

In order to avoid using toxic or harmful operational conditions, shorten synthesis time, enhance adsorption capacity, and reduce operational cost, a novel magnetic nano-adsorbent of CoFe₂O₄@SiO₂ with core⁻shell structure was successfully functionalized with polypyrrole (Ppy). The physical and chemical properties of CoFe₂O₄@SiO₂-Ppy are examined by various means. The as-prepared CoFe₂O₄@SiO₂-Ppy nanomaterial was used to adsorb Hg2+ from water. During the process, some key effect factors were studied. The adsorption process of Hg2+ onto CoFe₂O₄@SiO₂-Ppy was consistent with the pseudo-second-order kinetic and Langmuir models. The Langmuir capacity reached 680.2 mg/g, exceeding those of many adsorbents. The as-prepared material had excellent regeneration ability, dispersibility, and stability. The fitting of kinetics, isotherms, and thermodynamics indicated the removal was endothermic and spontaneous, and involved some chemical reactions. The application evaluation of electroplating wastewater also shows that CoFe₂O₄@SiO₂-Ppy is an excellent adsorbent for Hg2+ ions from water.