Fabrication Of Amine-modified GO/Fe₃O₄ Grafted PMAAM For The Adsorption Of Heavy Metal Ions

In recent years,a large number of industrial wastewater containing heavy metal ions is produced with the rapid development of the industries.Heavy metal ions could cause serious hazards to environment and living organism due to their characteristic of toxicity,difficult degradation and easy accumulation.Hence,it is very important research significance how to safely,economically and effectively remove toxic heavy metal ions from effluents before releasing them into the environment.In this study,using ethylenediamine and maleic anhydride as functional monomers,graphene oxide loaded magnetic Fe₃O₄ nanoparticles modified by?3-Aminopropyl?triethoxysilane as support,amino modified magnetic graphene oxide grafted polymaleicamide dendrimer?GO/Fe₃O₄-g-PMAAM?nanohybrids were fabricated by divergent method and magnetic separation technology.The surface morphology,structure and magnetic properties of the produced materials were characterized by transmission electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy,elementary analyzer,vibratingsamplemagnetometerandZetapotentialanalysis.GO/Fe₃O₄-g-PMAAM nanohybrids have been applied for the removal of Pb???and Hg???from aqueous solutions by batch experiments.The effects of PMAAM generations,solution pH value,initial concentration of Pb???and Hg???,contact time and temperature on the adsorption properties of GO/Fe₃O₄-g-PMAAM were investigated.The adsorption kinetics was described by the pseudo-first-order,pseudo-second-order,intra-particle diffusion and Elovich equation.Furthermore,the Langmuir,Freundlich,Temkin and Dubinin-Radushkevich models were employed to describe the equilibrium isotherms.The adsorption mechanism of the samples was investigated.The results showed that the amino modified magnetic graphene oxide grafteddifferentgenerationspolymaleicamidedendrimernanohybridswere successfully fabricated.Moreover,the prepared samples are superparamagnetic and satisfied the requirement of magnetic separation.GO/Fe₃O₄-g-PMAAM with generation 3.0 of PMAAM dendrimer?GO/Fe₃O₄-g-G3.0?has the maximum adsorption capacity to Pb???(181.4 mg·g^-1)and Hg???(107.8 mg·g^-1).The adsorption processes of GO/Fe₃O₄-g-G3.0 for Pb???and Hg???were all well fitted by the pseudo-second-order model and Langmuir isotherms model.The adsorption process was mainly considered as a monolayer chemical adsorption.The Hg???adsorbed on the surface of GO/Fe₃O₄-g-G3.0 were partially reduced to Hg?I?in the adsorption process.The Pb???ions were mainly complexed with-NH₂ on the surface of GO/Fe₃O₄-g-G3.0.