Amino-functionalized Graphene Oxide For Cr(?), Cu(?), Pb(?) And Cd(?) Removal From Industrial Wastewater

The problem of heavy metal polluted water bodies in China is serious and widespread,which poses a great threat to human health and the ecological environment.Heavy metal ions have the characteristics of carcinogenic teratogenicity,toxicity,and non-biodegradability,so the removal of heavy metal ions in water bodies needs to be solved.Amino-functionalized graphene oxide?GO?was synthesized by grafting?3-aminopropyl?triethoxysilane on the graphene oxide?GO?surface according to the hydrothermal method.The GO with high surface area and numerous active sites can efficiently adsorb Cr???,Cu???,Pb???and Cd???ions.Synthesis of graphene oxide by improved Hummers method,and synthesis of Amino-functionalized graphene by hydrothermal method of graphene oxide and triaminopropyl triethoxysilane.The synthesized adsorbent materials were characterized by scanning electron microscopy,transmission electron microscopy and infrared spectroscopy.The adsorption behavior was investigated under different pH values,contact times and initial metal ion concentrations.The maximum adsorption capacities of GO for Cr???,Cu???,Pb???and Cd???were 280.11,26.25,71.89 and 10.04 mg g^-1,respectively.The pseudo-first-order and pseudo-second-order kinetic models were employed to describe the adsorption kinetic processes.The experimental data agreed well with the pseudo-second-order kinetic equation,and the adsorption of heavy metals onto GO occurs via chemical adsorption.The characteristics of Cr???,Cu???,Pb???and Cd???in the GO-NH₂ adsorption processes were analyzed using the Langmuir and Freundlich isotherm models.The adsorption processes of Pb???and Cd???on GO-NH₂ were better fit by the Langmuir model than the Freundlich model,and the adsorption of Pb???and Cd???occurs via homogeneous adsorption on the GO-NH₂ surface.The Freundlich isotherm model was well correlated to Cr???and Cu???,implying that the active sites of the GO-NH₂ surface are heterogeneous for Cr???and Cu???sorption.The GO-NH₂ is a promising material for the removal of heavy metal ions from industrial wastewater.The application of the GO-NH₂ sorbent was investigated with an industrial wastewater sample from a metal smelting plant in northwest China,and the removal efficiencies of Cr???,Cu???,Pb???and Cd???are 79.19%,7.25%,93.41%and20.10%,respectively.This study provides an effective pathway to process industrial wastewater,and the GO-NH₂ has a good adsorption effect for the treatment of heavy metals in industrial wastewater.