Synergistic promotion of antimony transformation in the interaction of Acidithiobacillus ferrooxidans and pyrite by driving the formation of reactive oxygen species and secondary minerals.

As one of the important microorganisms in the mining area, the role of iron-sulfur oxidizing microorganisms in antimony (element symbolized as Sb) migration and transformation in mining environments has been largely neglected for a long time. Therefore, the processes of the typical iron-sulfur oxidizing bacterium Acidithiobacillus ferrooxidans (A. ferrooxidans) and pyrite interaction coupled with the migration and transformation of Sb were investigated in this paper. The bio-oxidation process of pyrite by A. ferrooxidans not only accelerates the oxidation rate of Sb(III) to Sb(V) (62.93% of 10 mg L within 4 h), but also promotes the adsorption and precipitation of Sb (32.89 % of 10 mg L within 96 h), and changes in the dosage of minerals, Sb concentration, and pH value affect the conversion of Sb. The characterization results show that the interaction between A. ferrooxidans and pyrite produces a variety of reactive species, such as HO and •OH, resulting in the oxidation of Sb(III). In addition, A. ferrooxidans mediates the formation of stereotyped iron-sulfur secondary minerals that can act as a major driver of Sb (especially Sb(V)) adsorption or co-precipitation. This study contributes to the further understanding of the diversified biogeochemical processes of iron-sulfur oxidizing bacteria-iron-sulfur minerals-toxic metals in mining environments and provides ideas for the development of in-situ treatment technologies for Sb.