Sulphide organic

Z 1 Niobium 1 Nitrate 1 Osmium 73 a. I Perchlorate Phenols u a o Platinum o 0. 1 5 u 1 Rhodium 1 Rubidium Ruthenium Scandium 1 Selenium Silver I Sodium 1 Strontium 1 Sulphate Sulphides, organic Sulphur dioxide 1 Tantalum 1 Tellurium 1 Thallium Thorium e H 1 Titanium a u ab a 1- I Uranium 1 Vanadium 1 Yttrium 1 Zinc Zirconium... 

Removal of dissolved sulphur compounds (sulphates, sulphides, organic sulphur compounds)... 

Combination of more exnaction instfuments, that is, their successive use on the same sample, had first been applied by Gibbs [81], in the course of examination of suspended river material, and afterwards this method, with various modifications and improvements, was used by a number of authors, amongst whom probably the best known are Tessier [82, 83] and Foersmer [84-87], Very quickly the authors adopted the division into phases, which logically ensues from chemical characteristics of applicable extraction instruments, in other words, extraction instruments which meet the criteria of efficiency and selectivity to the maximum. Under phases here are implied discrete physical phases of geological material (i.e. silicate, oxide, carbonate, sulphide, organic phase, as well as fractions of heavy metals associated with them) whilst in the case of non-selectively bound metals an expression sorptive or exchangeable phase. 

Sewage disposal sulphides / organically complexed sludges, soils... 

Sewage farms organic complexes/ sulphides organic complexes/ sulphides organic complexes/ sulphides... 

PPha, pyridine) organic groups (olefines, aromatic derivatives) and also form other derivatives, e.g. halides, hydrides, sulphides, metal cluster compounds Compounds containing clusters of metal atoms linked together by covalent (or co-ordinate) bands, metaldehyde, (C2H40) ( = 4 or 6). A solid crystalline substance, sublimes without melting at I12 1I5" C stable when pure it is readily formed when elhanal is left in the presence of a catalyst at low temperatures, but has unpredictable stability and will revert to the monomer, ft is used for slug control and as a fuel. 

Upon fusion with caustic alkah (for experimental details, see Section IV,33,2) and acidification of the aqueous extract, hydrogen sulphide is evolved (detected by lead acetate paper). This test is given by aU organic compounds of divalent sulphur (RSH, R SR" and R SSR"). 

The palladium may be recovered by heating the spent catalyst to redness in order to remove organic impurities this treatment may reduce some of the barium sulphate to barium sulphide, which acts as a catalytic poison. The palladium is then dissolved out with aqua regia and the solution evaporated the residue is dissolved in hot water and hydrochloric acid to form palladium chloride. 

In order to detect these elements in organic compounds, it is necessary to convert them into ionlsable inorganie substanees so that the ionic tests of inoiganio qualitative analysis may be applied. This conversion may be accomplished by several methods, but the best procedure is to fuse the organic compound with metallio sodium (Lassalgne s test). In this way sodium cyanide, sodium sulphide and sodium halides are formed, which are readily identified. Thus ... 

When an organic compound is heated with a mixture of zinc powder and sodium carbonate, the nitrogen and halogens are converted into sodium cyanide and sodium hahdes respectively, and the sulphur into zinc sulphide (insoluble in water). The sodium cyanide and sodium hahdes are extracted with water and detected as in Lassaigne s method, whilst the zinc sulphide in the residue is decomposed with dilute acid and the hydrogen sulphide is identified with sodium plumbite or lead acetate paper. The test for nitrogen is thus not affected by the presence of sulphur this constitutes an advantage of the method. 

Alkyl sulphides are the sulphur analogues of ethers from which they differ considerably in chemistry. They are unpleasant-smelling oils, insoluble in water but soluble in organic solvents. They tend to be comparatively inert. Mustard gas, CICH2CH2—S—CH2CH2CI, an oily liquid boiling at 216°C with a mustard-like smell, is highly poisonous and a vesicant, and for this reason found use in chemical warfare. 

Neutralization of strong mineral acids from metal finishing trades (sulphide and hypochlorite contamination common) Fierce reaction Possibility of mixing with water or organic materials Chlorine Nitrogen dioxide Sulphur dioxide Hydrogen sulphide... 

Sulphur.—The presence of sulphur in organic compounds may be detected by heating the substance with a little metallic sodium or potassium. The alkaline sulphide, when dissolved in water, gives a violet colouration with a solution of sodium nitro-prusside. Heat a fragment of gelatine with a small piece of potassium in a test-tube until the bottom of the tube is red hot, and place it m a small beaker of water as described in the test for nitrogen (p. 2). Filter the liquid and add a few drops of sodium nitroprusside solution. 

The presence of sulphur may indicate a sulphate of an organic base, alkyl sulphate, sulphite, sulphide, incrcaptan, sulphonit and, bisulphite unnpound of aldehyde or ketone. 

Hydrogen sulphide This is produced by the putrefaction of organic sulphur compounds or by the action of sulphate-reducing bacteria in anaerobic conditions (e.g. in polluted river estuaries). It is fairly rapidly oxidised to SOj and concentrations are considerably lower than those of (Table 2.6). Nevertheless it is responsible for the tarnishing of copper and silver at normal atmospheric concentrations. 

In sea-water systems such attack may occur under dead barnacles or shellfish, the decomposing organic matter assisting corrosion. Pitting is most likely to occur in polluted in-shore waters, particularly when hydrogen sulphide is present. In such contaminated waters non-protective sulphide scales are formed and these tend to stimulate attack. 

Patches of conductive lead sulphide can be formed on lead in the presence of sewage. This can result in the flow of a large corrosion current . Sulphate-reducing bacteria in soils can produce metal sulphides and H2S, which results in the formation of deep pits containing a black mass of lead sulphide . Other micro-organisms may also be involved in the corrosion of lead in soil . 

Sulphide solutions, sulphurous acid and some foodstuffs containing organic sulphur compounds, produce stains of sulphide, but the rate of loss of metal is low. Milk and milk products are usually without action, although local corrosion has been known to occur in dairy equipment. 

In general, near-neutral aqueous products are without action except for possible sulphide staining or, when there are dissolved salts present, some local corrosion. The slight acidity which may develop in solutions of some organic compounds such as formaldehyde or alcohols can be tolerated. 

The oil industry frequently uses stainless steels or exotic bonded alloys for the processing of crude oil in the temperature range 200-600°C. These materials are very expensive and there is a strong economic incentive for finding cheaper alloys which are resistant to HjS and some gaseous organic sulphides arising from the S content of the crude oil". ... 

Organic materials Corrosive vapours are sometimes emitted by organic materials used either in packaging or in the manufactured article, and may be troublesome in confined spaces. Some woods, particularly unseasoned oak and sweet chestnut, produce acetic acid (see Section 18.10), and certain polymers used in paints, adhesives and plastics may liberate such corrosive vapours as formic acid and hydrogen sulphide . It may be necessary to carry out exposure trials, particularly where materials capable of liberating formaldehyde or formic acid are involved. Most corrosion problems of this kind can be prevented by using desiccants, and in many cases they are confined to imperfectly cured materials. For an excellent review see Reference 9. 

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