Abstract
Graphene oxide (GO) was synthesized using the Hummers method and evaluated for lithium-ion removal from aqueous solutions. Characterization via X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) confirmed the presence of oxygen-containing functional groups (C-O-C, C=O), which act as active adsorption sites. BET analysis revealed a surface area of 232 m(2)/g and a pore volume of 0.4 cm(3)/g, indicating its high porosity. Lithium adsorption was tested using synthetic Li-doped solutions under controlled conditions. Kinetics and equilibrium studies demonstrated that the process followed the pseudo-second-order model and the Redlich-Peterson isotherm, achieving an optimum lithium adsorption capacity of 179 mg/g. The adsorption efficiency was influenced by factors such as pH and salinity. Regeneration experiments showed that HNO(3) was the most effective desorbing agent, enabling GO to be reused multiple times with a moderate loss of adsorption capacity. These findings highlight GO's exceptional efficiency in lithium removal and its suitability for wastewater treatment applications. Its recyclability and reusability further support a circular economy, making GO a highly promising material for sustainable lithium recovery and broader environmental remediation efforts.