Sulphur and Sulphides

Lead peroxide is even more active than the oxide. It reacts violently with sulphur and sulphides. When it is ground up with sulphur, the mixture combusts. With hydrogen sulphide, the reaction is very exothermic and causes peroxide to incandesce and hydrogen sulphide to combust. Finally, it reacts violently with calcium, strontium and barium sulphides on heating. 

Bacterial reduction of sulfate in an anaerobic environment with large isotope fractionation between the residual sulphate and the sulphide is the source of sulphur and sulphide in many deposits. The recognition that many sulphur... 

The carbonyls of tungsten and molybdenum are made similarly, both sulphur and sulphides catalysing the reactions. 

Reaction of Hydrogen with Sulphur and Sulphides and the Catalytic Decomposition of Hydrogen Sulphide... 

Relatively close to the term "geochemical engineering" is the technique of bacterial leaching. The technique is known for a long time from the treatment of metal-poor ores, where hydro- or pyrometallurgy is no more economically feasible. During these processes - mediated by specialized bacteria - oxidation of sulphur and sulphides produces sulphuric acid, and metals are mobilized such as copper. 

SULFUR.. In laboratoiy tests, 1100 and 3003 alloys were resistant to liquid sulfur at 135-154°C (275-3l0 F). Aluminum alloy equipment has been used for the recovery and purification of sulfur, in sulfur mining equipment, buildings, freight cars, hopper cars and conveyors. See also Ref (1) p. 145, (2) p. 800, (3) pp. 40, 227 James R. West. "Sulphur and Sulphides vs. Materials of Chemical Plant Ccm-struction," Chemical Engineering, 1946 October. 

WEIR R.G. 1975. The oxidation of elemental sulphur and sulphides in soil. In Sulphur in Australian Agriculture. Ed. McLachlan K. Sydney University Press. 

Arsenates(V) are more powerful oxidising agents than phos-phates(V) and will oxidise sulphite to sulphate, hydrogen sulphide (slowly) to sulphur and, depending on the conditions, iodide to iodine. 

Oxygen does not read with alkalis. Sulphur dissolves slowly in strong alkalis to give a mixture of sulphite [sulphate(IV)] and sulphide initially ... 

Chlorine will also remove hydrogen from hydrogen sulphide, liberating sulphur, and from ammonia, liberating nitrogen ... 

Sulphur, as sulphide ion, is detected by precipitation as black lead sulphide with lead acetate solution and acetic acid or with sodium plumbite solution (an alkaLine solution of lead acetate). Halogens are detected as the characteristic silver halides by the addition of silver nitrate solution and dilute nitric acid the interfering influence of sulphide and cyanide ions in the latter tests are discussed under the individual elements. 

Whereas some atoms have only one valency, others have several, e.g. sulphur has valencies of two, four and six and can form compounds as diverse as hydrogen sulphide, H2S (valency two), sulphur dioxide, SO2 (valency four) and sulphur hexafluoride, SF6 (valency six). Clearly some compounds comprise more than two different elements. Thus hydrogen, sulphur and oxygen can combine to produce sulphuric acid, H2SO4. From the structure it can be seen that hydrogen maintains its valency of one, oxygen two and sulphur is in a six valency state. 

Another method for slowing oxidation of rubber adhesives is to add a compound which destroys the hydroperoxides formed in step 3, before they can decompose into radicals and start the degradation of new polymer chains. These materials are called hydroperoxide decomposers, preventive antioxidants or secondary antioxidants. Phosphites (phosphite esters, organophosphite chelators, dibasic lead phosphite) and sulphides (i.e. thiopropionate esters, metal dithiolates) are typical secondary antioxidants. Phosphite esters decompose hydroperoxides to yield phosphates and alcohols. Sulphur compounds, however, decompose hydroperoxides catalytically. 

Other chemicals Copper and copper alloys are unsuitable for handling hydrogen peroxide " or molten sulphur . Hydrogen sulphide accelerates corrosion of most copper-base materials. In its presence brasses high in zinc are usually found to behave better than other copper alloys. ... 

The corrosion of tin by nitric acid and its inhibition by n-alkylamines has been reportedThe action of perchloric acid on tin has been studied " and sulphuric acid corrosion inhibition by aniline, pyridine and their derivatives as well as sulphones, sulphoxides and sulphides described. Attack of tin by oxalic, citric and tartaric acids was found to be under the anodic control of the Sn salts in solution in oxygen free conditions . In a study of tin contaminated by up to 1200 ppm Sb, it was demonstrated that the modified surface chemistry catalysed the hydrogen evolution reaction in deaerated citric acid solution. 

Niobium like tantalum relies for its corrosion resistance on a highly adherent passive oxide film it is however not as resistant as tantalum in the more aggressive media. In no case reported in the literature is niobium inert to corrosives that attack tantalum. Niobium has not therefore been used extensively for corrosion resistant applications and little information is available on its performance in service conditions. It is more susceptible than tantalum to embrittlement by hydrogen and to corrosion by many aqueous corrodants. Although it is possible to prevent hydrogen embrittlement of niobium under some conditions by contacting it with platinum the method does not seem to be broadly effective. Niobium is attacked at room temperature by hydrofluoric acid and at 100°C by concentrated hydrochloric, sulphuric and phosphoric acids. It is embrittled by sodium hydroxide presumably as the result of hydrogen absorption and it is not suited for use with sodium sulphide. 

It is also clear that small changes in the position of points P and Q can have a significant effect on the phase distribution in the surface layers. From the diagrams it is also seen that, when the metal A is saturated with oxygen and sulphur, and therefore the point Q is located at the corner of the rectangle giving the stability area of the metal A, then the innermost phase layer will consist of a mixed sulphide and oxide layer. 

For the use of diacetyl dithiol as a coagulant, catalyst and precipitant for sulphur and Group 11 sulphides, see Ref. 2. 

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