Preparation and characterization of amino/thiol bifunctionalized magnetic nanoadsorbent and its application in rapid removal of Pb (II) from aqueous system.

To explore the effect of coexisted amino and thiol groups on adsorption of heavy metal, a novel magnetic nanoparticle was prepared by sequentially modification with (3-Chloropropyl) trimethoxysilan, polyetherimide, epichlorohydrin and thiourea. Subsequently, it was characterized by TEM, N2 adsorption/desorption, FTIR Spectroscopy, zeta potential, and VSM. The maximum adsorption capacity for Pb2+, Cd2+ and Cu2+ reached 110.13 mg·g-1, 40.23 mg·g-1 and 29.37 mg·g-1, respectively. The adsorption of the magnetic nanoparticles with different surface group for heavy metals were compared, which indicated that the amino and thiol group played an important role in the adsorption of heavy metals. Especially, the adsorption capacity increased dramatically after modification with the thiol group, which was attributed to the synergistic coordination of -NH2 and -SH. The adsorption kinetics is consistent with the quasi-second-order kinetics equation, and the adsorption thermodynamic process is consistent with the Langmuir isotherm equation. The effects of experimental conditions, such as pH, the concentration of metals, adsorption time and temperature, on adsorption of Pb2+ were studied in detail. In addition, over 90% of removal rate was remained after 6 cycles. The magnetic nanoadsorbents was a promising nanoadsorbent with high adsorption speed, simultaneous adsorption of various heavy metals, strong anti-interference ability and reusability.