Development of glutamic acid-modified graphene oxide nanocomposites for efficient adsorptive removal of sulfanilamide residues from environmental water: Adsorption mechanism

• DOI: 10.1016/j.jwpe.2024.106443
• Publication Date: 2024-11-01T13:20:53Z
• Authors: Abdeslam Assafi; Lamia Hejji; Youssef Aoulad El...; Nordin Ben Seddik; Abdelmonaim Azzouz; Luis Pérez-Villarejo; Anass Wahby; Badredine Souhail; Eulogio Castro; Christian Sonne
• Keywords: Sulfanilamide; Glutamic acid

Antibiotic residues have become a global environmental concern, as these emerging contaminants are frequently detected in water bodies at concentrations exceeding ecotoxicity thresholds, posing risks to aquatic ecosystems and water quality. This study extensively evaluated the efficacy of glutamic acid-modified graphene oxide (GO@Glu) nanocomposites, synthesized via amidation, for the removal of sulfanilamide (SA) residues. The GO@Glu nanocomposites were characterized using a range of techniques, including X-ray diffraction (XRD), Fourier transform infrared analysis (FTIR), scanning electron microscopy (SEM), and UV–visible (UV–vis), and Brunauer–Emmett–Teller (BET). Batch experiments were conducted to assess the effects of adsorption time, initial SA concentration, GO@Glu dosage, solution pH, and temperature. The results demonstrated rapid adsorption kinetics and high adsorption capacities, exceeding 186.01 mg g−1 for SA at a low GO@Glu dosage (10 mg). The adsorption process was found to be homogeneous and dominated by physisorption. Further analysis indicated that the adsorption was endothermic and enthalpy-driven, with the GO@Glu nanocomposites exhibiting excellent recyclability. The adsorption mechanism was further investigated through thermodynamic studies, adsorption kinetics, isotherm modeling, and FTIR analysis of the GO@Glu sorbent before and after SA adsorption. Theoretical studies, including density functionl theory (DFT), molecular dynamics simulations (MDS), and quantum theory of atoms in molecules (QTAIM) analysis, revealed stronger interaction energies for GO@Glu compared to unmodified GO, which could be attributed to enhanced van der Waals and hydrophobic interactions between the nanocomposite's hydrophobic chains and SA molecules. Additionally, real water samples spiked with SA residues confirmed the efficient removal of SA using GO@Glu. Thus, GO@Glu nanocomposites show great potential as a promising candidate for the effective treatment of water contaminated with SA and related pharmaceutical residues.