Dendrimer-conjugated magnetic nanoparticles for removal of zinc (II) from aqueous solutions |
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Authors: | Chih-Ming Chou Hsing-Lung Lien |
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Institution: | (1) Department of Civil and Environmental Engineering, National University of Kaohsiung, 811 Kaohsiung, Taiwan, Republic of China; |
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Abstract: | Dendrimers are novel nanostructure materials that possess a unique three-dimensional molecular configuration. They have high
adsorption capacities of heavy metals. Dendrimer-conjugated magnetic nanoparticles (Gn-MNPs) combining the superior adsorbent
of dendrimers with magnetic nanoparticles (MNPs) have been developed for effective removal and recovery of Zn(II). In this
study, the Gn-MNPs were synthesized, characterized, and examined as reusable adsorbents of Zn(II). Characterization conducted
by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and elemental
analysis revealed that dendrimers were successfully coated onto the surface of MNPs made of magnetite (Fe3O4). The pH effect studies indicate the Zn(II) adsorption with Gn-MNPs is a function of pH. The adsorption efficiency increases
with increasing pH. At pH less than 3, Zn(II) is readily desorbed. Hence, the Gn-MNPs can be regenerated using the diluted
HCl aqueous solution (0.1 M) where Zn(II) can be recovered in a concentrated form. It was found that the Gn-MNPs underwent
10 consecutive adsorption–desorption processes still retained the original removal capacity of Zn(II). The adsorption data
were fitted well with both Langmuir and Freundlich isotherms. The maximum adsorption capacity determined by the Langmuir model
is 24.3 mg/g at pH 7 and 25°C. A synergistic effect between the complexation reaction and the electrostatic interaction may
account for the overall performance of Gn-MNPs. |
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