Green Reduction of Waste-Battery-Derived Graphene Oxide by Jute Leaves and Its Application for the Removal of Tetracyclines from Aqueous Media

In recent years, contamination of aquatic ecosystems by antibiotics, especially tetracyclines (TCs), has become a significant concern. In this study, we have synthesized reduced graphene oxide (GrGO) using jute leaf extract as a green reducing and stabilizing agent for the reduction of graphene oxide (GO). The GO itself was synthesized from graphite derived from waste dry-cell batteries, making the process simple and cost-effective. We aimed to explore its potential as an adsorbent for the rapid and efficient removal of TCs from aqueous media. Characterization of GO and GrGO was carried out using FTIR, FESEM, EDX, and XRD techniques, revealing the successful reduction of GO to GrGO. The adsorption of TCs by GrGO was performed in a batch of experiments to assess the effect of adsorbent (GrGO) dose, solution pH, contact time, and temperature to find out the optimal condition of adsorption. The quantitative analysis of TCs before and after adsorption was conducted by using liquid chromatography–mass spectrometry (LC-MS/MS). Under optimal conditions, 98% of tetracycline (TEC), 97% of oxytetracycline (OTC), and 97% of chlortetracycline (CTC) were successfully removed from aqueous solutions. The adsorption isotherm of TCs onto GrGO fit well with the Freundlich isotherm model, while the kinetic data were best described by the pseudo-second-order model. The maximum adsorption capacity (q_m) of GrGO for TEC, OTC, and CTC were found to be 22.85, 18.53, and 22.23 mg/g, respectively. Notably, the GrGO adsorbent demonstrated the ability to be reused effectively. Thermodynamic studies confirmed that the adsorption process is spontaneous and endothermic. The rapid and effective removal of these TCs was primarily governed by electrostatic and nonbonding interactions on the surface of GrGO. The findings indicate that green-synthesized GrGO is an effective and promising low-cost adsorbent for the removal of TCs from aqueous solutions.