Highly Efficient Adsorption of Heavy Metals onto Novel Magnetic Porous Composites Modified with Amino Groups

A novel porous magnetic composite CoFe2O4-SiO2 (CF-S) was prepared by a simple template method. After facile amino-functionalization, it exhibited bigger adsorption capacity and higher removal efficiency (>90%) for all the heavy metal ions (Cu(II), Mn(II), Cd(II), and Pb(II)) in single or mixed metal ions solution. The adsorption affinity for heavy metal ions was not much impacted by the presence of competitive ions. Moreover, effects of experimental parameters, including adsorbent dosage, solution pH, initial concentration, reaction temperature and time, were discussed. The isothermal adsorption results were well described by the Langmuir model, and the maximum adsorption capacities were 429.18 mg center dot g(-1) (25 degrees C), 500.00 mg center dot g(-1) (35 degrees C), 523.56 mg center dot g(-1) (45 degrees C), and 555.51 mg center dot g(-1) (55 degrees C) for Cu(II) ions. The adsorption kinetics fitted well with pseudo-second order kinetic model. Analysis of thermodynamic study for Cu(II) showed that the process of adsorption was spontaneous and endothermic in nature. The results indicated that the excellent adsorption was attributed to chemical adsorption through strong surface complexation, as well as the special structure of the CF-S-N composite.