Polyvinylpyrrolidone functionalized magnetic graphene-based composites for highly efficient removal of lead from wastewater

Abstract Lead (Pb) is one of the significant pollutants in environment. A maximum value of 0.01 mg/L in drinking water has been set by many countries. Thus, it is indispensible for the selective removal of Pb below 0.01 mg/L (10 ppb) in the wastewater treatment. In the study, a reusable magnetic graphene-based composites functionalized with polyvinylpyrrolidone (PVP/Fe3O4/GO composites) are reported to remove Pb(II) ions from water with highly selective and efficient. The water dispersity and pH tolerance are significantly improved by the PVP decoration. Comparison of PVP/Fe3O4/GO composites with Fe3O4/GO and PVP/GO composites reveals that PVP/Fe3O4/GO composites have higher adsorption capacity with 793.65 mg/g and higher separation factor (αPb). Such composites can remove 99.74% of Pb(II) from coexisting metal ions including Na(I), K(I), Mg(II), Mn(II), Cu(II), Zn(II), Cr(III) and Cd(II) with a high separation factor of the order 10 to 103. The mechanism of Pb(II) removal is mainly dependent on the electrostatic interaction between Pb(II) and –COOH of Fe3O4/GO as well as the chemical absorption between Pb(II) and the PVP group. Additionally, PVP/Fe3O4/GO composites have been applied to treat different wastewater samples with over 90% of removal efficiency. Especially in river water sample, Pb(II) ions can be declined to ∼0.4 ppb after treating, demonstrating its great potential in wastewater treatment.