Synthesis and sustainable assessment of thiol-functionalization of magnetic graphene oxide and superparamagnetic Fe3O4@SiO2 for Hg(II) removal from aqueous solution and petrochemical wastewater

Adsorbents used in adsorption processes play an important role in wastewater treatment technologies. It is therefore of interest how manufactured adsorbents can perform better or be more efficient. Is the adsorption capacity a sufficient indicator to select a good adsorbent? In this study, two nanoadsorbents of Hg(II) were successfully synthesized. They are magnetic graphene oxide (MGO-NH-SH) and magnetic nanoparticle (Fe3O4@SiO-NH-SH), both functionalized with a thiol group, acetylcysteine. The nanoadsorbents, in addition to their adsorption capacity, were investigated from the viewpoints of reuse and regeneration, economic costs, and environmental impact (carbon footprint). The prepared nanoadsorbents were characterized by FTIR, XRD, TGA, FE-SEM, VSM, AFM, Raman, and elemental analysis. Their adsorption of Hg(II) fits well with the Langmuir isotherm model and follows the pseudo-second-order kinetics. Under optimal conditions, the results of Hg(II) removal from real wastewater and polluted water by MGO-NHSH exhibited a higher adsorption capacity, reuse, and regeneration, and as well lower cost and greenhouse gas emissions compared to Fe3O4@SiO-NH-SH. The findings of the present study highlight that MGO-NHSH as a promising adsorbent is more economically and environmentally friendly than Fe3O4@SiO-NH-SH in the efficient removal of Hg(II) from real wastewater and polluted water. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.