Oxidizing elemental sulfur

Displacement of the sulfhydryl group in primary thiols, like L cysteine and 2-diethylaminoethanethiol, requires elemental fluorine, the most active oxidant Elemental sulfur is the major by-product in those reactions [7] (equation 2)... 

Cork [283], Sublette [284], and others have identified a number of chemolithotrophic bacteria which oxidize elemental sulfur and use reduced or partially reduced sulfur compounds as an energy source, in the presence of various carbon sources (such as carbon dioxide or bicarbonate) and reduced nitrogen (e.g., ammonium ion). In the case of Cork et al. s work, the anaerobic photosynthetic bacterium Chlorobium thiosulfatophilum is used to convert sulfides to sulfate. The economics of this process was not favorable due to the requirement of light for the growth of the bacterium. 

In general, sulfide is oxidized via sulfite to sulfate, while thiosulfate can either be oxidized only to tetrathionate or may be split into sulfide and sulfite. Both compounds are then further oxidized to sulfate. During anaerobic sulfide or thiosulfate oxidation, elemental sulfur appears as sulfur globules inside or outside the cells. Sulfur metabolism in Anoxyphotobacteria has two main functions ... 

Reaction of [W2(OCH2Bu )8] with pyridine-A -oxide, elemental sulfur, selenium, and Bu 3PTe afforded [W 2(/r-E)(/a-OCH2Bu02(OCH2Bu06] (E = O, S, Se, or Te). 

Acidithiobacillus ferrooxidans anaerobically oxidizes elemental sulfur and formate with ferric ion (Sugio et al., 1985 Pronk et al., 1991a Das et al., 1992). The bacterial oxidation of elemental sulfur and formate with ferric ion is inhibited by HOQNO but not by azide. In the oxidation of elemental sulfur with ferric ion free energy of 75 kcal/S° is liberated, which is enough to support the growth of the bacterium. Thus, the bacterium grows anaerobically by oxidizing elemental sulfur with ferric ion (Pronk et al., 1992). 

C4HsCd04 Noncombustible solid. The solution is basic reacts with acids, producing heat. Incompatible with strong oxidizers, elemental sulfur, selenium, sulfides, tellurium, nitrates. In the heat of fire, toxic cadmium oxide fumes may form. CADMIUM BROMIDE (7789-42-6) CdBrj Noncombustible solid. Hydrolyzes in water, forming cadmium and bromic acid. Reacts with sulfides. Aqueous solution is inconqiatible with potassium. Incompatible with sulhiric acid, alkalis, ammonia, aliphatic amines, alkanolamines, alkylene oxides, amides, epichlorohydrin, organic anhydrides, isocyanates, nitromethane, vinyl acetate. 

ACETATO CADMIO (Spanish) (543-90-8) Incompatible with strong oxidizers, elemental sulfur, selenium, sulfides, tellurium, strong acids, nitrates. 

CADMIUM CHLORIDE (10108-64-2) Violent reaction with bromium trifluoride, potassium. Contact with acids, acid fumes forms toxic chloride fumes. Incompatible with strong oxidizers, elemental sulfur, selenium, tellurium. Austenitic stainless steels are susceptible to pitting attack and stress corrosion in the presence of chlorides. 

CHEMICAL PROPERTIES combustible tarnishes in moist air slowly oxidized by moist air to form cadmium oxide highly corrosion resistant corrosion resistance poor in industrial atmospheres lowers melting point of certain alloys when used in low percentages resistant to alkalies reacts vigorously with strong oxidizers, elemental sulfur, selenium and tellurium. 

T. thiooxidans bacteria are active in drained marine environments high in elemental sulfur. Thiobacillus denitriflcans can oxidize elemental sulfur in the presence of nitrate under anaerobic conditions as depicted below ... 

A variety of heterotrophic bacteria are capable of oxidizing elemental sulfur to sulfate. 

Incompatibilities and Reactivities Strong oxidizers elemental sulfur, selenium tellurium... 

CADMIUM DUST (AS CD) Cd Synonyms vary depending upon spcciHc compounds Strong oxidizers, elemental sulfur, selenium, tellurium Properties vary depmding upon spcdAc compound ... 

Figure 10.10 The sulfur cycle showing the role of bacteria in oxidizing elemental sulfur to sulfate and in reducing sulfate to sulfide [27],...

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