Investigating Glycine and Hexamethylenediamine Functionalized Magnetic Graphene Oxide for Removing Pb2+ from Aqueous Solutions

This study is reserved for the synthesis, characteristics, and evaluation of the adsorption efficiency of nanocomposite-based adsorbents based on functionalized magnetic graphene oxide (MGO). The chemical structure and bond formation, crystal structure, and pollutant adsorption by the adsorbent were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and atomic absorption spectroscopy, respectively. The optimization process was analyzed using response surface methodology, considering four independent variables: adsorbent weight, initial pH solution, adsorption time, and Pb2+ concentration. A comparative analysis was conducted on functionalized MGO samples with hexamethylenediamine (MGO-HMDA) and glycine (MGO-Gly) regarding Pb2+ removal. Investigating the kinetic and isotherm studies toward the adsorbent, it was observed that the adsorption processes follow second-order kinetics and Freundlich isotherm. Thermodynamic studies, including Gibbs free energy changes, enthalpy, and entropy changes, show that the adsorption process is spontaneous and exothermic. The maximum adsorption rate obtained is 86% and 98.38% respectively for MGO-Gly and MGO-HMDA with operational parameters including adsorbent weight (16 mg), initial solution pH (10), adsorption time (23 min), and initial Pb2+ concentration (15 mg/L). Therefore, the HMDA functionalized nanocomposite was realized to be an acceptable adsorbent for pb2+ from an aqueous solution.