Synthesis of a graphene oxide-based zerovalent iron nanocomposite for efficient remediation of Re(VII) from simulated wastewater in high pH

In this study, nanoscale zero-valent iron was successfully soldered onto graphene oxide to synthesize nZVI/rGO nanocomposite by an improved modified Hummers' method. The nZVI/rGO nanocomposite was used to remove Re(VII) in water remediation , which was utilized as a replacement for the radioactive element of Technetium-99 (99Tc). The results showed that nZVI/rGO could effectively remove Re(VII) at pH = 13 with a removal efficiency of 99.1 %. rGO can effectively inhibit the aggregation of nZVI and significantly improve the removal performance. The removal capacity of nZVI minus the removal capacity of rGO in the composite was as high as 468.8 and 474.9 mg/g, respectively, corresponding to the mass ratio of Fe 0 :rGO = 1:1 and 1:2. However, the removal capacity of pure nZVI was only 33.5 mg/g, and that of the pure rGO was 42.6 mg/g. The removal capacity of Re(VII) by nZVI/rGO was not affected by cations of Na + , Ca 2+ , K + , and Mg 2+ ions. The removal efficiency of Fe 0 :rGO with a mass ratio of 1:1 and 1:2 was still higher than 60 % (63.5 % and 67.1 %, respectively). The results of this study demonstrate that the graphene oxide-based zerovalent iron nanocomposite under an appropriate mass ratio, can economically and efficiently remediate rhenium heavy metal ions in high pH water environments.