Microbial oxidation of Fe21 and pyrite exposed to flux of micromolar H2O2 in acidic media

At an initial pH of 2, while abiotic oxidation of aqueous Fe21 was enhanced by a flux of H2O2 at micromolarconcentrations, bio-oxidation of aqueous Fe21 could be impeded due to oxidative stress/damage inAcidithiobacillus ferrooxidans caused by Fenton reaction-derived hydroxyl radical, particularly when themolar ratio of Fe21 toH2O2 was low. When pyrite cubes were intermittently exposed to fluxes of micromolarH2O2, the reduced Fe21-Fe31 conversion rate in the solution (due to reduced microbial activity) weakenedthe Fe31-catalyzed oxidation of cubic pyrite and added to relative importance of H2O2-driven oxidation inthe corrosion of mineral surfaces for the treatments with high H2O2 doses. This had effects on reducing thebuild-up of a passivating coating layer on the mineral surfaces. Cell attachment to the mineral surfaces wasonly observed at the later stage of the experiment after the solutions became less favorable for the growth ofplanktonic bacteria