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

Abstract

Abstract 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 NH-SH 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 NH-SH 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.