Iron L-edge and sulfur K-edge XANES spectroscopy analysis of pyrite leached by Acidianus manzaensis
(1. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Biometallurgy of Ministry of Education of China, Central South University,
Changsha 410083, China;
3. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China)
2. Key Laboratory of Biometallurgy of Ministry of Education of China, Central South University,
Changsha 410083, China;
3. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China)
Abstract: Iron L-edge and sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy analysis of pyrite leached by extreme thermophilic Archaea strain Acidianus manzaensis (A. manzaensis) was carried out. Leaching experiments show that the oxidation of pyrite can be accelerated by A. manzaensis. Leaching results show that with the increase of leaching time, pH value in the leaching solution gradually decreases, redox potential increases rapidly from day 0 to day 3, and then increases slowly. The SEM results show that the pyrite surfaces are corroded gradually by A. manzaensis, and the XRD results show that the leaching residues contain new compositions of jarosite and elemental sulfur (S0). The iron L-edge XANES spectroscopy analysis of pyrite during biooxidation indicates that pyrite is gradually converted to Fe(III)-containing species. The sulfur K-edge XANES spectroscopy analysis indicates that elemental sulfur is produced during bioleaching and maintains mass fractions of 3.2%-5.9%. Sodium thiosulfate was also detected from day 2 to day 4, indicating the existence of thiosulfate during biooxidation of pyrite.
Key words: pyrite; bioleaching; chemical speciation; XANES; Acidianus manzaensis