Self- immobilized bio-nanomaterials based on hybridized green reduced graphene and Burkholderia vietnamiensis C09V for enhanced removal of Sb species from mine wastewater

Abstract

Elevated levels of antimony (Sb) in the environs of smelters or mines can pose significant human and environmental health risks, where efficient removal of Sb species from mine wastewater is currently a challenge. In this paper, a functional reduced graphene hybrid Burkholderia vietnamiensis C09V biomaterial (RGO-B.V. C09V) was initially synthesized by self-immobilization and subsequently used to remove 100% of Sb(III) within 24 h and 90.0% of Sb(V) within 120 h. This removal efficiency was also much higher than that of free B.V. C09V alone, which removed 100% of Sb(III); but only 26.7% of Sb(V); within 120 h. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) confirmed that Burkholderia vietnamiensis C09V (B.V. C09V) was firmly immobilized on the RGO surface with an abundant distribution of extracellular polymeric substances (EPS). Three-dimensional excitation-emission matrix (3D-EEM) analysis and electrochemical techniques were used to confirm the function of RGO as a potential electron shuttle and the composition of EPS to identify its key role in any redox reactions. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis confirmed that polysaccharides and protein-like substances on the surface of RGO-B.V. C09V participated in the biosorption of Sb via complexation. When RGO-B.V. C09V was practically used to treat a mine wastewater the final Sb concentration decreased by 96% from 0.12 to 0.005 mg·L−1. RGO-B.V. C09V also exhibited high stability, with removal efficiencies of up to 100% for Sb(III), and 72% for for Sb(V) after 4 reuse cycles, with no regeneration. The results showed that RGO-B.V. C09V was a stable, environmentally friendly bionanomaterial suitable for the practical removal of Sb species from mine wastewater over a sustained period.