Toxic metal removal from aqueous solution by advanced Carbon allotropes: a case study from the Sungun Copper Mine

The sorption efficiencies of graphene oxide (GO) and functionalized multi-walled carbon nanotubes (f-MWCNTs) were investigated and elucidated to study their potential in treating acid mine drainage (AMD) containing Cu2+, Mn2+, Zn2+, Pb2+, Fe3+ and Cd2+ metal ions. Several layered GO nanosheets and f-MWCNTs were formed via the modified Hummers’ method and the acid treatment of the MWCNTs, respectively. The prepared nanoadsorbents were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transformed infrared (FTIR) spectroscopy, and BET surface area analysis. The batch method was utilized to evaluate the pH effect, sorption kinetics and isotherms. The results demonstrated that the sorption capacities of the MWCNTs increased greatly after oxidation and those of the GO decreased after reduction. Hence, the sorption mechanisms seemed principally assignable to the chemical interactions between the metal ions and the surface functional groups of the adsorbents. Additionally, the adsorption isotherm results clearly depicted that the adsorption of the Cu2+ ion onto the GO adsorbent surface was well fitted and found to be in good agreement with the Langmuir isotherm model as the obtained regression constant value (R2) was found to be 0.9981. All results indicated that GO was a promising material for the removal of toxic metal ions from aqueous solutions in actual pollution management.