Removal of Cd (II), Pb (II) and Cu (II) ions from aqueous solution by polyamidoamine dendrimer grafted magnetic graphene oxide nanosheets

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Abstract In this study, the as-synthesized magnetic graphene oxide (mGO) nanocomposite was grafted with amine groups, namely the first and second generation of polyamidoamine dendrimer (mGO1st- and mGO2nd-PAMAM) with different oxidation levels and shown to be effective in removing Cd (II), Pb (II) and Cu (II) ions from aqueous solution in batch system. Raman spectroscopy, atomic force microscopy (AFM), Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to identify the structural characteristics of amine functionalized nanocomposites. The pHZPC value of the sorbent was estimated to be 7.2 by titration methods. The different amine functionalization of the mGO stage of the two adsorbents and the differences in the behavior of the three metal ions under magnetic strength were found to be important in order to consider the performance of the adsorption systems. The adsorption capacities of metal ions were 435.85, 326.729 and 353.59 mg g−1 for Cd (II), Pb (II) and Cu (II), respectively. The obtained data were successfully fitted with the pseudo-second-order kinetic model. The adsorption capacity was dependent on the temperature and increased with the increase of temperature. Also, the equilibrium data were evaluated using the Freundlich, Langmuir, and Redlich–Peterson (R–P) isotherm models, suggesting the obtained data were fitted to the Freundlich isotherm model and the adsorption mechanism is heterogeneous. According to thermodynamic analysis, the adsorption process was found to be endothermic and spontaneous in nature. Moreover, the adsorbent was regenerated after a five time adsorption–desorption cycle without significant loss in adsorption capacity. The results from this study support that the as-synthesized adsorbent proves excellent removal ability of the metal ion from water and wastewater.