Synthesis of Holey Graphene Oxide and Its Application as an Adsorbent for Heavy Metal Removal from Aqueous Solutions

Improving advanced materials for the removal of heavy metal ions in aquatic systems is an urgent need because the contamination of waters by heavy metals causes significant environmental toxicity. In this study, holey graphene oxide (hGO), an advanced version of graphene oxide, was synthesized and its potential use as an adsorbent in a dispersive solid phase extraction (d-SPE) technique was evaluated. The characterization of hGO was achieved by Fourier-transform infrared spectroscopy, X-ray diffraction, field emission digital scanning electron microscope, Brunauer-Emmett-Teller, and energy-dispersive X-ray spectroscopy-mapping techniques. The adsorption performance of hGO on the simultaneous removal of Pb (II), Ni (II), Cd (II), Co (II), and Cu (II) metal ions was evaluated by the d-SPE method, and the optimization results revealed that quantitative removal of heavy metal ions was achieved at pH 4 for 200 s of equilibrium by using 50 mg of adsorbent. The results demonstrated that hGO exhibited competitive performance, achieving removal efficiencies of 97.8% [Pb (II)], 94.2% [Ni (II)], 97.4% [Cd (II)], 96.5% [Co (II)], and 91.6% [Cu (II)] at optimum conditions for targeted heavy metals. The optimized d-SPE method was applied to remove the heavy metal ions in certified reference material and real water samples. The hGO showed potential as an efficient adsorbent for water remediation from heavy metal pollution.