Enhanced removal and recovery of heavy metals from acid mine drainage using nFeS@GS biosynthesized by Geobacter sulfurreducens

Efficient removal and recovery of heavy metals (HMs) from acid mine drainage (AMD) is crucial for both protecting mine ecosystems and reclaiming valuable HMs resources. In this study, biohybrid with ferrous sulfide nanoparticles ( n FeS@GS) were biosynthesized via Geobacter sulfurreducens (GS) and employed for the removal and recovery of HMs from AMD. Initially, n FeS@GS were successfully synthesized as confirmed by TEM and exhibited high efficiencies in removing Cu 2+ and Pb 2+ in solution, respectively. This occurred because bio- n FeS and GS cells synergistically enhanced the removal of Cu 2+ and Pb 2+ . What is more, the removal efficiencies of various HMs from real AMD using n FeS@GS remained high, with documented rates of 87.9 % for Cu 2+ , 96.2 % for Pb 2+ , 95.1 % for Cd 2+ , 81.4 % for Ni 2+ , 80.9 % for Mn 2+ , and 91.9 % for Zn 2+ . Subsequent characterization of the removal function through 3D-EEM, Bio-TEM, XRD, FTIR and XPS analyses revealed substantial organic capping agents derived from GS adhering to the bio- n FeS, forming surface complexes with Cu 2+ and Pb 2+ , and Cu 2+ was reduced to Cu + /Cu 0 . Zeta potential measurements, adsorption kinetics and reduction kinetics supported that the removal mechanism involved electrostatic interactions, surface complexation, ion exchange and reduction. Finally, n FeS@GS desorption rates of HMs exceeded 90.7 %, highlighting the efficacy of n FeS@GS for recovering HMs from AMD. These findings provide valuable and practical insights into the removal and recovery of HMs from AMD using biomaterials synthesized from microorganisms.