Pyrite oxidation under initially neutral pH conditions
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چکیده
Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Biogeosciences Discussions This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Abstract Hydrogen peroxide (H 2 O 2) 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 H 2 O 2 , the colonization of Acidithiobacillus ferrooxi-dans onto the mineral surface was markedly enhanced, as compared to the control 5 (no added H 2 O 2). This can be attributed to the effects of H 2 O 2 on increasing the roughness of the mineral surfaces, as well as the acidity and Fe 2+ concentration at the mineral-solution interfaces. All of these effects tended to create more favourable nano-to micro-scale environments in the mineral surfaces for the cell adsorption. However, higher H 2 O 2 levels inhibited the attachment of cells onto the mineral surfaces, possibly 10 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 H 2 O 2 as an oxidant caused marked surface flaking of the mineral surface. The XPS results suggest that H 2 O 2 accelerated the oxidation of pyrite-S and consequently facilitated the overall corrosion cycle of pyrite surfaces. This was 15 accompanied by pH drop in the solution in contact with the pyrite cubes.
منابع مشابه
Interactive comment on “Pyrite Oxidation under initially neutral pH conditions and in the presence of Acidithiobacillus ferrooxidans and micromolar hydrogen peroxide” by Y. Ma and C. Lin
Authors Response to the Comments by Reviewer 3 General comments Reviewer’s Comment: The manuscript “Pyrite Oxidation under initially neutral pH conditions and in the presence of Acidithiobacillus ferrooxidans and micromolar hydrogen peroxide” submitted by Y. Man and C. Lin, is interesting in so far as the studies about this issue are relatively scarce. However, in my opinion, selected pyrite cu...
متن کاملInteractive comment on “Pyrite Oxidation under initially neutral pH conditions and in the presence of Acidithiobacillus ferrooxidans and micromolar hydrogen peroxide” by Y. Ma and C. Lin
This work represents the first attempt to examine pyrite oxidation in a complex system involving iron/sulfide-oxidizing bacteria, molecular oxygen and intermittent fluxes of hydrogen peroxide at micromolar levels. As also pointed out by Reviewer #4, investigation of such a complex system is quite difficult to perform, we did not intend to set an unrealistic high bar for this study. As stated in...
متن کاملInteractive comment on “Pyrite Oxidation under initially neutral pH conditions and in the presence of Acidithiobacillus ferrooxidans and micromolar hydrogen peroxide” by Y. Ma and C. Lin
This work represents the first attempt to examine pyrite oxidation in a complex system involving iron/sulfide-oxidizing bacteria, molecular oxygen and intermittent fluxes of hydrogen peroxide at micromolar levels. As also pointed out by Reviewer #4, investigation of such a complex system is quite difficult to perform, we did not intend to set an unrealistic high bar for this study. As stated in...
متن کاملInteractive comment on “Pyrite Oxidation under initially neutral pH conditions and in the presence of Acidithiobacillus ferrooxidans and micromolar hydrogen peroxide” by Y. Ma and C. Lin
Reviewer’s Comment: I agree with the other reviewers that studies on pH neutral (bio)oxidation of pyrite and other sufidic minerals are rare. Maybe, because these investigations are quite difficult to perform, as they require a profound knowledge of both the microbiology and the surface chemistry and, consequently, a strong cooperation of these research disciplines. Nevertheless, considering th...
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