Preparation of Novel Magnetic PGA@SiO₂@Fe₃O₄ Composite Nanoparticles for Heavy Metal Ion Removal

Kang-long Chen, Qing-han Zhou*

The novel magnetic adsorbent was prepared by functionalization of magnetic nanoparticles with Poly-γ-glutamate (PGA), and the sorbent is named as PGA@SiO₂@Fe₃O₄. The composite nanoparticles were further used in retrieval of heavy metal ions such as Pb(II) from the aqueous medium. The preparation of PGA@SiO₂@Fe₃O₄ involves a two-step process: (i) surface modification of Fe₃O₄ nanoparticles by ethyl orthosilicate (TEOS) to form SiO₂@Fe₃O_4, (ii) surface functionalization of SiO₂@Fe₃O₄ nanoparticles by free radical copolymerization to form a cross-linking magnetic PGA@SiO₂@Fe₃O₄ nanoparticles. The chemical structure of the PGA, Fe₃O₄, SiO₂@Fe₃O₄, and PGA@SiO₂@Fe₃O₄ was characterized by ¹H-NMR, and FTIR. The nano-size and surface morphologies of the adsorbent were analyzed by SEM and DLS. Finally, the adsorbent was used to adsorb Pb (II), and the effects of different factors such as initial concentration, adsorption time, adsorption dosage, pH, and temperature on the adsorbent and adsorption were studied.