Pyrite oxidation under initially neutral pH conditions and in the presence of Acidithiobacillus ferrooxidans and micromolar hydrogen peroxide

Ma, Y. and Lin, C. (2012) Pyrite oxidation under initially neutral pH conditions and in the presence of Acidithiobacillus ferrooxidans and micromolar hydrogen peroxide. Biogeosciences Discussions, 9. pp. 557-579. ISSN 1810-6277 (Submitted)

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Abstract

Hydrogen peroxide (H2O2) at a micromolar level played a role in the microbial surface oxidation of pyrite crystals under initially neutral pH. When the mineral-bacteria system was cyclically exposed to 50 μM H2O2, the colonization of Acidithiobacillus ferrooxidans onto the mineral surface was markedly enhanced, as compared to the control(no added H2O2). This can be attributed to the effects of H2O2 on increasing the roughness of the mineral surfaces, as well as the acidity and Fe2+ concentration at the mineral-solution interfaces. All of these effects tended to create more favourable nanoto micro-scale environments in the mineral surfaces for the cell adsorption. However, higher H2O2 levels inhibited the attachment of cells onto the mineral surfaces, possibly due to the oxidative stress in the bacteria when they approached the mineral surfaces where high levels of free radicals are present as a result of Fenton-like reactions. The more aggressive nature of H2O2 as an oxidant caused marked surface flaking of the mineral surface. The XPS results suggest that H2O2 accelerated the oxidation of pyrite-S and consequently facilitated the overall corrosion cycle of pyrite surfaces. This was accompanied by pH drop in the solution in contact with the pyrite cubes.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: No
Item Status: Live Archive
Additional Information: Published online 16 January 2012. ArticleFirst version deposited in accordance with the copyright policy of the publisher. © Author(s) 2012. CC Attribution 3.0 License.
Depositing User: Dr Chuxia Lin
Faculty / Department / School: Current - USQ Other
Date Deposited: 06 Nov 2012 05:10
Last Modified: 03 Jul 2013 01:31
Uncontrolled Keywords: Acidithiobacillus ferrooxidans; pyrite oxidation; hydrogen peroxide
Fields of Research (FOR2008): 04 Earth Sciences > 0402 Geochemistry > 040299 Geochemistry not elsewhere classified
Socio-Economic Objective (SEO2008): D Environment > 96 Environment > 9612 Rehabilitation of Degraded Environments > 961205 Rehabilitation of Degraded Mining Environments
Identification Number or DOI: doi: 10.5194/bgd-9-557-2012
URI: http://eprints.usq.edu.au/id/eprint/22084

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