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The oxidation of reduced sulfur compounds is performed exclusively by Bacteria and Archaea.All the Archaea involved in this process are aerobic and belong to the Order Sulfolobales, [19] [20] characterized by acidophiles (extremophiles that require low pHs to grow) and thermophiles (extremophiles that require high temperatures to grow).
The sulfide ion does not exist in aqueous alkaline solutions of Na 2 S. [3] [4] Instead sulfide converts to hydrosulfide: S 2− + H 2 O → SH − + OH −. Upon treatment with an acid, sulfide salts convert to hydrogen sulfide: S 2− + H + → SH − SH − + H + → H 2 S. Oxidation of sulfide is a complicated process.
These processes typically produce hydrogen sulfide as a byproduct, which can go on to serve as an electron donor in sulfur oxidation. [11] Sulfate reduction by sulfate-reducing bacteria is dissimilatory; the purpose of reducing the sulfate is to produce energy, and the sulfide is excreted.
Sulfur Oxidation. Sulfur can also be oxidized to sulfuric acid by chemolithotrophic bacteria, such as Thiobacillus and Acidithiobacillus. S 0 + 2O 2 → H 2 SO 4. Sulfur Reduction. Some bacteria are capable to reduce sulfur to sulfide enacting a sort of anaerobic respiration. This process can be carried out by both sulfate reducing bacteria and ...
Sulfur can be found under several oxidation states in nature, mainly −2, −1, 0, +2 (apparent), +2.5 (apparent), +4, and +6. When two sulfur atoms are present in the same polyatomic oxyanion in an asymmetrical situation, i.e, each bound to different groups as in thiosulfate, the oxidation state calculated from the known oxidation state of accompanying atoms (H = +1, and O = −2) can be an ...
The increased resistance to corrosion found in stainless steel is attributed to a layer of chromium oxide that forms due to oxidation of the chromium found in the alloy. [4] The process of liquid sulfidation has also been used in the manufacturing of diamond-like carbon films. These films are generally used to coat surfaces to reduce the wear ...
The bacterial oxidation process comprises contacting refractory sulfide ROM ore or concentrate with a strain of the bacterial culture for a suitable treatment period under an optimum operating environment. The bacteria oxidise the sulfide minerals, thus liberating the occluded gold for subsequent recovery via cyanidation.
Supergene processes include the predominance of meteoric water circulation (i.e. water derived from precipitation) with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements.