Investigation of functionalized magnetic graphene oxide using glycine and hexamethylenediamine ligands to remove Pb 2+ from aqueous solutions

Abstract

Abstract This work is reserved to the synthesis, characteristics, and evaluation of the adsorption efficiency of nanocomposite-based adsorbents based on functionalized magnetic graphene oxide. The chemical structure and bond formation, crystal structure, and pollutant absorption 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 CCD and RSM, taking into account four independent variables including adsorbent mass, initial pH solution, agitation time and Pb2+ concentration. A comparative analysis was carried out on functionalized magnetic graphene oxide samples with HMDA and Gly regarding Pb2+ removal. Investigating the kinetic and isotherm studies toward the adsorbent and its resumption in successive sorption and desorption cycles, 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 absorption process is spontaneous and exothermic. The maximum adsorption rate obtained have been found as 86% and 98.38% respectively for as-synthesized and functionalized adsorbent by Gly and HMDA with operational parameters including adsorbent mass (5–25 mg), initial solution pH (2–10), agitation time (5–45 min), and initial Pb2+ concentration (5–25 mg.L− 1), Therefore, the HMDA functionalized nanocomposite was realized to be an acceptable adsorbent for pb2+ from an aqueous solution.