Inhibition of Microbial Pyrite Oxidation by PropS-SH for the Control of Acid Mine Drainage

Acidithiobacillus ferrooxidans, an acidophilic sulfur and iron-oxidizing microorganism, plays an important role in the oxidation of FeS2 and the formation of acid mine drainage (AMD). In this study, the stability of gamma-mercaptopropyltrimethoxysilane(PropS-SH) treated pyrite in the presence of Acidithiobacillus ferrooxidans was investigated by electrochemical techniques in conjunction with bioleaching approach. In addition, the chemical and morphological characteristics of pyrite before and after coated by PropS-SH were analyzed with X-ray photoelectron spectrometer (XPS) and contact angle tests. The results from electrochemical tests indicated that the coating of PropS-SH significantly decreased electrochemical activity of pyrite in bioleaching solutions. The results of bioleaching experiments showed that PropS-SH coating could effectively suppress the release of S and Fe species from pyrite and inhibit the growth of bacteria. These results were attributed to the formation of a hydrophobic layer on pyrite surface by chemisorption of PropS-SH which could limite the contact of bacteria with pyrite.