Magnetic Graphene Oxide Grafted With Different Hydrophobic Chain Lengths Low-Generation Polyamidoamine Dendrimers for Adsorption of Pb(II) and Hg(II) in Aqueous Solution

In this study, using hexamethylenediamine (HMD)-modified magnetic graphene oxide (HMGO-NH2) as carrier, HMD and methyl acrylate as function monomers, MGO grafted with longer hydrophobic chain length low-generation HMD type polyamidoamine dendrimers (HMGO-PAMAM-G1.0) was prepared by Michael addition and amidation condensation reaction. The obtained HMGO-PAMAM-G1.0 sample was characterized by transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherms, thermal properties analysis, vibrating sample magnetometer, and X-ray photoelectron spectroscopy analysis. The adsorption properties for Pb(II) and Hg(II) heavy metal ions of HMGO-PAMAM-G1.0 and the magnetic graphene oxide grafted with shorter hydrophobic chain length low-generation ethylenediamine type polyamidoamine dendrimers (MGO-PAMAMG1.0) reported in our previous work were explored. The results showed that the HMGO-PAMAM-G1.0 with longer hydrophobic chain length had higher adsorption capacity for Pb(II) and Hg(II) than MGO-PAMAM-G1.0 at the higher concentrations. The adsorption process of HMGO-PAMAM-G1.0 and MGO-PAMAM-G1.0 for Pb(II) and Hg(II) was well in agreement with pseudo-second-order kinetic model and the Langmuir isotherm model. The Pb(II) was only adsorbed on the sample, while the Hg(II) was partially reduced to Hg(I) in the adsorption process. (C) 2018 Society of Plastics Engineers