Facile and Efficient Synthesis of Nitrogen-Functionalized Graphene Oxide as a Copper Adsorbent and Its Application

In this work, we report a room-temperature approach to synthesizing nitrogen-functionalized graphene oxide (GO). The chemical structure of GO- triethylenetetramine-methacrylate (GO-TETA-MA) was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and C-13 nuclear magnetic resonance, respectively. The GO-TETA-MA demonstrated extremely efficient removal of copper from wastewater. The adsorption capacity was found to be 34.4 mg/g for Cu(II) (at pH = 5 and 25 degrees C). The final concentration of Cu(II) was lower than the quality standard for groundwater and even lower than the allowable level of copper contaminant in drinking water in China. The effects of several parameters on adsorption, including pH value, contact time, adsorption temperature, initial concentration, acid stability, and thermal stability, were investigated. Kinetic data were well-described by a pseudo-first-order model. Both Freundlich and Langmuir isotherm models were applied to the experimental data analysis, and the former proved to be a better fit. The underlying mechanism of synergistic adsorption of heavy metal ions was considered. Then, the removal efficiency for four copper fungicides was studied and was found to reach 100%. These results suggest that GO-TETA-MA has the potential to be applied in environmental management.