Green One-Step Approach to Prepare Sulfur/Reduced\nGraphene Oxide Nanohybrid for Effective Mercury Ions Removal

Abstract

A one-step, eco-friendly strategy\nis developed to prepare sulfur/reduced\ngraphene oxide nanohybrid (SRGO) (sulfur nanoparticles of average\nsize ∼20 nm) using the combined effect of the polyphenolic\ncompounds and acids present in <i>Citrus limon</i> juice.\nThe prepared nanohybrid is characterized with Fourier transform infrared,\nRaman spectroscopy, X-ray diffraction, and transmission electron microscopy.\nThe detailed plausible mechanism of the simultaneous reduction of\ngraphene oxide and formation of sulfur nanoparticles is also established.\nThe nanohybrid demonstrated a fast and efficient Hg²⁺ removal\nat around pH 6–8. The adsorption kinetics followed pseudosecond-order\nand the isotherm could be well described by the Langmuir model. The\nthermodynamic parameters (Δ<i>G</i>⁰, Δ<i>S</i>⁰, and Δ<i>H</i>⁰) are calculated from the temperature-dependent isotherms and indicate\nthat the adsorption process is endothermic and spontaneous. The nanohybrid\nalso has excellent reusability and high selectivity of Hg²⁺. Therefore, this nanohybrid has use as a promising toxic Hg²⁺ adsorbent.