Adsorption of Pb(II) and Cd(II) by functionalized graphene oxide (GO-MBT): Mechanisms, antibacterial activity, and DFT studies

Abstract

Contamination of natural water with heavy metals is an ongoing environmental challenge and warrants the advancement of purification technologies. The present research deals with the synthesis and fabrication of graphite from coconut shell and subsequently to graphene oxide (GO) and thiol-functionalized GO-MBT adsorbents for the removal of heavy metals from aqueous medium. The synthesized GO and GO-MBT were characterized by employing HR-TEM, XPS, EDX, FTIR, FE-SEM, TGA, AAS and XRD. The adsorption kinetics followed the pseudo-second-order model with regression coefficients close to 1(0.99) for both Pb(II) and Cd(II). Thiol-functionalized GO-MBT showed the adsorption capacity of GO-MBT for Pb(II) and Cd(II) with a value of 116.959 mg/g at pH 6 and 112.99 mg/g at pH 7 respectively. The GO-MBT exhibited impressive adsorption efficiency towards heavy metal ions Pb(II) and Cd(II) owing to the presence of high density of oxygen and sulfur-containing groups. DFT calculations provide valuable insights into the structural and energy properties of GO and GO-MBT, supporting their stability and reactivity. Besides, the antibacterial activities of developed adsorbents were determined using the agar well diffusion method and broth dilution method. The developed GO-MBT could be used as an effective adsorbent for the removal of Pb(II) and Cd(II) and bacterial species from contaminated water.