Arsenic Precipitation in the Bioleaching of Realgar Using Acidithiobacillus ferrooxidans

The current study investigates the characteristics of arsenic precipitation during the bioleaching of realgar. The bioleaching performance of Acidithiobacillus ferrooxidans BY-3 (A. ferrooxidans) was investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectrophotometry. SEM and XRD analyses revealed that the arsenic-adapted strain of A. ferrooxidans was more hydrophobic and showed higher attachment efficiency to realgar compared with the wild strain. The arsenic precipitation using A. ferrooxidans resulted in the precipitation of an arsenic-rich compound on the surface of the bacterial cell, as shown in the TEM images. The FT-IR spectra suggested that the −OH and −NH groups were closely involved in the biosorption process. The observations above strongly suggest that the cell surface of A. ferrooxidans plays a role in the induction of arsenic tolerance during the bioleaching of realgar.