Using amine-functionalized magnetite hollow nanospheres (AMHNs) as adsorbents for heavy metal ions

In this paper, the amine-functionalized magnetite hollow nanospheres (AMHNs), prepared through a facile one-pot synthesis, were used as heavy metal ion adsorbents, whose morphology and physicochemical features were exploring by transmission electron microscopy, vibrating sample magnetometer, X-ray diffraction and Fourier-transform infrared analyses. Its adsorption performances for Pb²⁺, Cu²⁺, Zn²⁺, Ni²⁺ and Cd²⁺ were studied in detail. The adsorption increased with the increase of initial pH value of the solution and could be obviously affected by ionic strength. Also, the adsorption kinetics and isotherms were studied. The adsorption processes for Pb²⁺, Cu²⁺, Zn²⁺, Ni²⁺ and Cd²⁺ could all reach equilibrium in 60 min and be described well by the Langmuir thermodynamics model. The saturated adsorption capacities for Pb²⁺, Cu²⁺, Zn²⁺, Ni²⁺ and Cd²⁺ were 0.66, 0.47, 0.45, 0.38 and 0.26 mmol/g, respectively. In addition, the competitive adsorption showed the AMHNs had higher affinity to Pb²⁺ than to other heavy metal ions.