Abstract
Magnetic water-soluble hyperbranched polyol functionalized graphene oxide nanocomposite (MWHPO-GO) was successfully prepared and applied to water remediation in this paper. MWHPO-GO was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), magnetization curve, zeta potential, scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. MWHPO-GO exhibited excellent adsorption performance for the removal of synthetic dyes (methylene blue (MB) and methyl violet (MV)) and heavy metal (Pb(II)). Moreover, MWHPO-GO could be simply recovered from water with magnetic separation. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these three pollutants. The thermodynamic results (ΔG < 0, ΔH < 0, ΔS < 0) implied that the adsorption process of MB, MV and Pb(II) was feasible, exothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where π-π stacking interactions, H-bonding interaction and electrostatic attraction dominated the adsorption of MB/MV and chelation and electrostatic attraction dominated the adsorption of Pb(II). In addition, the excellent reproducibility endowed MWHPO-GO with the potential for application in water remediation.
Highlights
Magnetic nanoparticles (MNPs) can be facilely separated from sample solution by applying an external magnetic field, which affords a rapid and economic approach to remove the toxic compounds from large-volume samples
In order to endow the composite adsorbent with well magnetic separation property, Fe3O4 magnetic particles were coupled with water-soluble multifunctional hyperbranched polyol (WHPO) by using IPDI to generate magnetic WHPO (MWHPO)
MWHPO was grafted onto graphene oxide (GO) surfaces through the reaction between amine groups of MWHPO and carboxyl groups of GO, which could introduce hydroxyl and amine groups onto the GO surface and increase the adsorption efficiency of dyes and heavy metals
Summary
Magnetic nanoparticles (MNPs) can be facilely separated from sample solution by applying an external magnetic field, which affords a rapid and economic approach to remove the toxic compounds from large-volume samples. Water-soluble polymers containing many desired functional groups are typically chosen to modify Fe3O4 nanoparticles to improve dispersion properties in aqueous solutions as well as the adsorption capacity. Ge and co-workers[13] prepared novel Fe3O4@APS@AA-co-CA MNPs nanoparticles and found these particles could efficiently remove the heavy metal ions such as Cd2+, Zn2+, Pb2+ and Cu2+ from aqueous solution with high maximum adsorption capacity. Due to the scarcity of surface functional groups and aggregation via van der Waals interactions, the adsorption capacities of graphene nanoadsorbents is limited[15]. Fe3O4 magnetic particles, water-soluble multifunctional hyperbranched polyol (WHPO) were combined with high surface area GO to prepare a novel nanosorbent (MWHPO-GO) for the high efficiency removal of both synthetic dyes and heavy metals. To further evaluating the practical applications, the effect of coexisting ions and the regeneration performance of MWHPO-GO were investigated
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