Bioelectrochemical and Spectroscopic Study during Interfacial Biooxidation Process of Chalcopyrite Mediated By Sulfur and Iron Oxidizing Microorganisms
So, in this work the objective is analyze the electrochemical process of system bacteria - electrolyte – mineral on modified chalcopyrite surface exhibting different sulfur species exposed to SOM and SOM+IOM cultures. For this the chemical changes in electrolyte, and morphological, composition and hydrophobic modifications on surface exposed to microorganisms are correlated with Electrochemical impedance Electrochemical (EIS) and Electrochemical Noise (EN) data obtained for each evaluated condition.
Global analysis of the results shows that the presence of microorganisms improves the ionic and electronic activity of interface, due to the initial sulfur phases (Sn2- and S0) generated by potentiostic oxidation were removed. Then, a secuencial and cyclic transformation between several kinds of reactive sulfur species, determined the electroactivity and hydrophobicity of chalcopyrite surface as a function of bioleaching time, which influences the oxidation capacity of microorganisms. In addition, it was found that on Sn2- rich surfaces, oxidation was improved with SOM, by an uniform mechanism of acidic dissolution and through indirect contact, these associated with SOM membrane enzymatic characteristics, according to [2,7]. However, on S0 rich surfaces, the bacterial activity occurred by direct contact, but was slower than on Sn2-, due to generation of hydrophobic and inactive (passive) sulfur species. Such kind of phases were result of a low amount of EPS-Fe3+ complexes that limited the ring sulfur activation, based in the reported in , and therefore the charge transfer and diffusion processes. On the other hand, SOM+IOM showed higher activity by an uniform mechanism of ferric dissolution on both sulfur phases, but it was mainly by direct contact on initial S0 surface, generating predominantly hydrophilic and reactive surfaces species at early times, which was associated to higher amount of EPS-Fe3+, that contributed with either fast activation of initial ring S0  and mass transfer.
 Klauber C, Int J Miner Process, 86:1-17 (2008).
 Meyer B, Chem Rev, 64 (4):429-451 (1964).
 Pan HD, Yang HY, Tong LL, Zhong CB, Zhao YS Trans Nonferrous Met Soc China 22:2255−226 (2012)
 Anjum F, Shahid M, Akcil A, Hydrometallurgy 1-12:117-118 (2012).
 González D, Lara R, Valdez-PÚrez D, Alvarado K, Navarro-Contreras H, Cruz R, García-Meza JV Appl Microbiol Biotechnol 93:763–775 (2012).
 Lara R, García-Meza JV, González I, Cruz R, Appl Microbiol Technol 95, 799 (2012).
 Franz B, Lichtenberg H, Hormes J, Modrow H, Dahl V, Prange A, Microbiol 153:1268-1274 (2007).