Adsorption performance of Pb(II) ions on green synthesized GO and rGO: Isotherm and thermodynamic studies

Abstract

Graphene oxide (GO) and reduced graphene oxide (rGO) are efficient and low-cost adsorbent carbon-based materials for removing Pb(II) ions from wastewater. In this article, the adsorption performance of environmentally friendly graphene oxide and reduced graphene oxide, which shows high adsorption capacity for Pb(II) ions, has been compared for the first time to our knowledge. Besides, the various characterization techniques are used such as X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy and described in detail as well. In addition, adsorption isotherms and thermodynamic studies are discussed to comprehend the adsorption process as well. From the adsorption isotherms, the maximum adsorption capacities of Pb(II) ions on GO and rGO calculated from the Langmuir (117.6 mg/g) and Dubinin–Radushkevich isotherms (138.5 mg/g), respectively, higher than reported studies in the literature. By thermodynamic investigation, it was found that the adsorption of Pb(II) ions on GO and rGO was spontaneous and exothermic. This study will be established as a basis for future studies and will be especially valuable in understanding the potential of graphene-based materials, which are rising stars that can be considered as promising and effective adsorbents in the removal of heavy metal ions from large volumes of aqueous solutions.