Superior Heavy Metal Ion Adsorption Capacity in Aqueous Solution by High-Density Thiol-Functionalized Reduced Graphene Oxides.

ABSTRACT: The preparation of mercapto-reduced graphene oxides (m-RGOs) via a solvothermal reaction using P₄S₁₀ as a thionating agent has demonstrated their potential as an absorbent for scavenging heavy metal ions, particularly Pb²⁺, from aqueous solutions due to the presence of thiol (-SH) functional groups on their surface. The structural and elemental analysis of m-RGOs was conducted using a range of techniques, including X-ray diffraction (XRD), Raman spectroscopy, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy equipped with energy-dispersive spectroscopy (STEM-EDS), and X-ray photoelectron spectroscopy (XPS). At pH 7 and 25 °C, the maximum adsorption capacity of Pb²⁺ ions on the surface of m-RGOs was determined to be approximately 858 mg/g. The heavy metal-S binding energies were used to determine the percent removal of the tested heavy metal ions, with Pb²⁺ exhibiting the highest percentage removal, followed by Hg²⁺ and Cd²⁺ ions having the lowest percent removal, and the binding energies observed were Pb-S at 346 kJ/mol, Hg-S at 217 kJ/mol, and Cd-S at 208 kJ/mol. The time-dependent removal study of Pb²⁺ ions also yielded promising results, with almost 98% of Pb²⁺ ions being removed within 30 min at pH 7 and 25 °C using a 1 ppm Pb²⁺ solution as the test solution. The findings of this study clearly demonstrate the potential and efficiency of thiol-functionalized carbonaceous material for the removal of environmentally harmful Pb²⁺ from groundwater.

SUBMITTER: Kim HG 

PROVIDER: S-EPMC10220523 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature