| 초록 |
Heavy metals are defined as transition metals or metalloids with a density higher than 5.0 g•cm-1. Especially, some of heavy metals (e.g., Ni, As, Pb, Cd, Hg etc.) have a very high toxicity even at a low concentration. The emission of these toxic heavy metals has been continuously increased with the rapid growth of industries. Thus, much effort has been tried to remove the heavy metals from contaminated water. Among them, branched polyethylenimine (b-PEI) is known as a good chelating polymer of the heavy metals. In this study, we developed a reusable adsorbent by introduction of b-PEI to magnetite particles. The synthesized b-PEI functionalized magnetite (P-MG) can effectively chelate the heavy metals. Furthermore, it is easily separated from water by external magnetic field. In order to prepare the P-MG, amine-functionalized magnetite (A-MG) was synthesized by hydrothermal method. Next, the P-MG was formed by covalent assembly of b-PEI to surface of A-MG using cyanuric chloride as a linking agent. The combined results of wide angle X-ray diffraction (WXRD) and transmission electron microscopy (TEM) reveal the formation of magnetite phase in the P-MG. The assembly of the b-PEI was confirmed by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The saturation magnetization of P-MG confirmed by vibrating sample magnetometry (VSM) is similar to that of the A-MG, which indicates that the P-MG is enough to be used for the repeated magnetic separation. Maximum adsorption capacities of the P-MG for Cu2+ and Pb2+ were estimated by Langmuir model. In addition, the adsorption capacity of the P-MG was well maintained during the repeated recycling process. Thus, the overall results suggest that the P-MG can be used as separable and reusable adsorbent with high efficiency for removal of heavy metals in contaminated water. |
