Comparative study of adsorption performances of lead (II) ions on green synthesized graphene oxide and reduced graphene oxide: isotherm and thermodynamic studies

Graphene oxide (GO) and reduced graphene oxide (rGO) are efficient and low-cost adsorbent carbon-based materials for removing Pb(II) ions from wastewater. This study focuses on the synthesizing GO and rGO by green methods with Tour approach and reduction with L-ascorbic acid, respectively and were characterized by X-ray diffraction, Fourier transform infra-red spectroscopy, Raman spectroscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy. The prepared GO and rGO were used to adsorb Pb(II) ions from aqueous solutions. 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.