Sulfur-oxidising

Hydrogen sulfide can be oxidised to elemental sulfur, for example, by green and purple sulfur bacteria. Further oxidation of elemental sulfur by sulfur oxidising bacteria can produce sulfate. 

Microbial interactions among aerobic and anaerobic sulfur-oxidising bacteria. Adv. Microbial. Ecol. 8, 1—59. 

Sulfur-oxidising bacteria convert inorganic sulfur compounds to sulfuric acid that can cause severe damage to mineral material. Thiobacillus species have been implicated with concrete corrosion in the Melbourne and Hamburg sewer systems due to sulfuric acid formation. However, a role in stone decay is less certain since sulfuric acid and calcium sulfate in stone can originate from the direct action of atmospheric pollution and acid rain. 

Considerable damage is also caused to concrete and marble by sulfur oxidising bacteria capable of producing acids. 

W. Sand, E. Bock, D. C. White, Biotest system for rapid evaluation of concrete resistance to sulfur-oxidising bacteria . Materials Performance, 1987, 26, 14-17. 

SRB - Sulfate reducing bacteria. SOB - Sulfur oxidising bacteria. 

Acetaldehyde [75-07-0] (ethanal), CH CHO, was first prepared by Scheele ia 1774, by the action of manganese dioxide [1313-13-9] and sulfuric acid [7664-93-9] on ethanol [64-17-5]. The stmcture of acetaldehyde was estabhshed in 1835 by Liebig from a pure sample prepared by oxidising ethyl alcohol with chromic acid. Liebig named the compound "aldehyde" from the Latin words translated as al(cohol) dehyd(rogenated). The formation of acetaldehyde by the addition of water [7732-18-5] to acetylene [74-86-2] was observed by Kutscherow] in 1881. 

Because of the mixture of VOCs in the atmosphere, the composition of smog reaction products and intermediates is extremely complex. formed via reaction 16, is important because when dissolved in cloud droplets it is an important oxidant, responsible for oxidising SO2 to sulfuric acid [7664-93-9] H2SO4, the primary cause of acid precipitation. The oxidation of many VOCs produces acetyl radicals, CH CO, which can react with O2 to produce peroxyacetyl radicals, CH2(C0)02, which react with NO2... 

The aHphatic iodine derivatives are usually prepared by reaction of an alcohol with hydroiodic acid or phosphoms trHodide by reaction of iodine, an alcohol, and red phosphoms addition of iodine monochloride, monobromide, or iodine to an olefin replacement reaction by heating the chlorine or bromine compound with an alkaH iodide ia a suitable solvent and the reaction of triphenyl phosphite with methyl iodide and an alcohol. The aromatic iodine derivatives are prepared by reacting iodine and the aromatic system with oxidising agents such as nitric acid, filming sulfuric acid, or mercuric oxide. 

Nitric acid is a strong monobasic acid, a powerful oxidising agent, and nitrates many organic compounds. Until the end of the nineteenth century, it was made by heating a metallic nitrate salt with less volatile concentrated sulfuric acid. Removal of the volatile nitric acid permits the reaction to go to completion. This method is still used for laboratory preparation of the acid. 

Phosphoric acid, aside from its acidic behavior, is relatively unreactive at room temperature. It is sometimes substituted for sulfuric acid because of its lack of oxidising properties (see SuLFURic ACID AND SULFURTRIOXIDe). The reduction of phosphoric acid by strong reducing agents, eg, H2 or C, does not occur to any measurable degree below 350—400°C. At higher temperatures, the acid reacts with most metals and their oxides. Phosphoric acid is stronger than acetic, oxaUc, siUcic, and boric acids, but weaker than sulfuric, nitric, hydrochloric, and chromic acids. 

These catalysts contained promoters to minimise SO2 oxidation. Second-generation systems are based on a combined oxidation catalyst and particulate trap to remove HC and CO, and to alleviate particulate emissions on a continuous basis. The next phase will be the development of advanced catalysts for NO removal under oxidising conditions. Low or 2ero sulfur diesel fuel will be an advantage in overall system development. 

Analytical Methods. The official NIOSH recommended method for determining sulfur dioxide in air consists of drawing a known prefiltered volume of air through a bubbler containing hydrogen peroxide, thus oxidising the sulfur dioxide to sulfuric acid. Isopropyl alcohol is then added to the contents in the bubbler and the pH of the sample is adjusted with dilute perchloric acid. The resultant solution is then titrated for sulfate with 0.005 M. barium perchlorate, and Thorin is used as the indicator. 

Tantalum is not resistant to substances that can react with the protective oxide layer. The most aggressive chemicals are hydrofluoric acid and acidic solutions containing fluoride. Fuming sulfuric acid, concentrated sulfuric acid above 175°C, and hot concentrated aLkaU solutions destroy the oxide layer and, therefore, cause the metal to corrode. In these cases, the corrosion process occurs because the passivating oxide layer is destroyed and the underlying tantalum reacts with even mild oxidising agents present in the system. 

Titanium carbide is resistant to aqueous alkaU except in the presence of oxidising agents. It is resistant to acids except nitric acid, aqua regia, and mixtures of nitric acid with sulfuric or hydrofluoric acid. In oxygen at 450°C, a nonprotecting anatase coating forms. The reaction... 

Chlorates are strong oxidising agents. Dry materials, such as cloth, leather, or paper, contaminated with chlorate may be ignited easily by heat or friction. Extreme care must be taken to ensure that chlorates do not come in contact with heat, organic materials, phosphoms, ammonium compounds, sulfur compounds, oils, greases or waxes, powdered metals, paint, metal salts (especially copper), and solvents. Chlorates should be stored separately from all flammable materials in a cool, dry, fireproof building. 

A remarkable complex with the composition Co2(R2C fc)5BF4 resulted from an attempt of Hendrickson and Martin (81) to oxidise Co(R2r/tc)3- These authors report diamagnetic, ionic complexes, in which the metal atoms are bridged by two sulfur atoms of the ligands, as is found for Ru2(Et2(irc)5BF4 (77). 

Table 5-5. Comparison of Fe—S bond lengths (A) for oxidised and reduced states of iron-sulfur protein, Rd...

Finely divided carbon, sulfur or red phosphorus are oxidised violently by silver chlorite. 

A literature procedure whereby bromopyrimidine is oxidised by excess peroxy-acetic acid in acetone, with sulfuric acid catalysis, was being scaled up. The crude product from the fourth batch at two molar scale was filtered out and allowed to dry to dry in the sintered glass funnel over the weekend. An explosion occurred when it was scraped out to complete purification on the Monday. This was considered due to acetone peroxides, which had probably concentrated locally by wicking or sublimation. 

Preparation by oxidising tris(phenanthroline)cobalt(III) tetrafluoroborate with nitric acid in sulfuric acid with potassium bromide catalysis is potentially explosive. See Nitric acid... 

During hydrolysis of crude dimethoxy compound by heating in sulfuric acid, a runaway exothermic decomposition occurred causing vessel failure. Experiment showed a threshold decomposition temperature of 150-155°C, and an oxidising effect of the nitro groups, yielding CO and CO2 above 162°C. 

Precautions are necessary to prevent explosions when using the mixed acids to oxidise organic materials for subsequent analysis. The sulfuric acid probably tends to dehydrate the 70% perchloric acid to produce the hazardous anhydrous acid. See Nitric acid, etc., above... 

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