Removal of Pb(II), Cd(II), and Zn(II) from landfill soil and leachate using a graphene oxide membrane

Abstract

Since rainwater extracts toxic metals from landfills, creating harmful leachate, developing methods to remove these metals is necessary. This work presents a method of toxic metal ions removal from a loam-type soil consisting of washing the soil with a mild washing agent to extract toxic metals in a leachate, and a purification of the leachate by filtering it through a synthesized graphene oxide (GO) membrane. As washing agents, the pure water and a mild solution of HCl (0.01 M) were tested. The GO membrane was synthesized using natural Madagascar graphite. The solution of HCl showed a significantly higher washing efficiency of Zn(II), Cd(II), and Pb(II) cations than pure water due to its acidic nature. An intrinsic GO membrane with an interlayer distance of 0.68–0.74 nm (before and after filtration) and a thickness of ~0.70 µm yielded rejections of 99.80%, 96.15%, and 44.00% for Pb(II), Cd(II) and Zn(II) ions, respectively. Molecular dynamics simulation showed that ions are retained in the GO interfaces due to the narrow interlayer distance, leading to membrane fouling. Nevertheless, the high rejections of Pb(II) and Cd(II) support the possibility of purifying landfill soil leachate by the GO membrane.