Sodium pyrophosphate,

Humic acids are alkaH-extractable materials and total humic acid content is a term that refers to the humic acid content of coal that has had its carboxylate cations removed with sodium pyrophosphate. Values for some typical AustraHan brown coals range from 24—92% (13). Treatment of lignitic coals with mineral acid to release the alkaH and alkaline cations may dissolve up to 20% of the coal. The naturally moist coals are slightly acidic and have a pH of 3.5—6.5. 

Sodium pyrophosphate peroxohydrate, Na4P202 2H2O2, was made commercially by PMC in the 1960s but was discontinued. It is less stable than sodium peroxoborate and sodium carbonate peroxohydrate in the soHd state, but more stable than these in solution. Many other phosphate peroxohydrates of the Group 1 and Group 2 metals are known but have found no uses. 

Compositions having an oxide ratio, i < 2, eg, in equation 11, can dehydrate to form more highly condensed phosphates beyond the pyrophosphate. Conditions must therefore be controlled to prevent complete dehydration. Insoluble pyrophosphates are obtained by treatment of a soluble salt of the desired cation using a sodium pyrophosphate solution. 

Sodium Pyrophosphates. Known pyrophosphate compounds in the Na20—H2O—P20 system are given in Table 10. Commercially important sodium pyrophosphates include tetrasodium pyrophosphate (TSPP), Na4P20y, and disodium pyrophosphate, Na2H2P20y, commonly referred to as sodium acid pyrophosphate (SAPP). These are prepared industrially by thermal dehydration of disodium and monosodium orthophosphate, respectively. Tetrasodium pyrophosphate exists in five crystalline modifications, only one of which is stable at room temperature. 

Polyphosphoric acid, P2O5, POCl, and PCl are suitable phosphorylatiag agents. Reaction of an alkyl sulfate with sodium pyrophosphate has also been reported for preparation of alkyl pyrophosphates (77). In general, phosphorylation leads to a mixture of reaction products that are sold without further separation. Thus, when lauryltri(ethyleneoxy)ethanol reacts with 0.3 mol of P2O5 at 50°C and is neutralized with 50% aqueous NaOH, the reaction mixture contains the foUowiag products ... 

Several agents deUvered via toothpaste inhibit the accumulation of dental calculus. Pyrophosphate salts, with or without a methoxyethylene—maleic acid copolymer, and zinc salts have given positive results in clinical trials (5). Pyrophosphates were added as potassium or sodium pyrophosphate or mixtures at a level of about 2—6%. The zinc salt was zinc citrate [546-46-3] (0.5—2.0%) or zinc chloride [7646-85-7] (2.0%). The products all contained fluoride in addition to the calculus inhibitor. The anticaries activity of the fluoride was not compromised (6). 

Elastomeric Fibers. Elastomeric fibers are polyurethanes combiaed with other nonelastic fibers to produce fabrics with controlled elasticity (see Fibers, elastomeric). Processing chemicals must be carefully selected to protect all fibers present ia the blend. Prior to scouriag, the fabrics are normally steamed to relax uneven tensions placed on the fibers duriag weaving. Scouriag, which is used to remove lubricants and siting, is normally conducted with aqueous solutions of synthetic detergents and tetrasodium pyrophosphate, with aqueous emulsions of perchloroethylene or with mineral spidts and sodium pyrophosphate. 

Prepare also a saturated solution of the purest available sodium pyrophosphate (do not heat above 25 °C, otherwise appreciable hydrolysis may occur) 12 g of the hydrated solid Na4P2O7,10H2O will dissolve in 100-150 mL of water according to the purity of the compound. It is essential to employ freshly made sodium pyrophosphate solution in the determination. 

Pyrolusite. Dissolve 1.5-2 g, accurately weighed, pyrolusite in a mixture of 25 mL of 1 1 hydrochloric acid and 6 mL concentrated sulphuric add, and dilute to 250 mL. Filtration is unnecessary. Titrate an aliquot part containing 80-100 mg manganese add 200 mL freshly prepared, saturated sodium pyrophosphate solution, adjust the pH to a value between 6 and 7, and perform the potentiometric titration as described above. 

Sodium Pyrophosphate Hydrogen Peroxide, Na407P3.2H202 Ibid Ibid... 

Far less than the stoichiometric amount of sequestrants precipitation of insoluble salts from water hardness can be prevented by slowing down the formation of crystals and crystal growth. This process is called the threshold effect. It has long been used in the preparation of boiler feeding water, e.g., steam vessels of railroad engines. Originally sodium pyrophosphate was used for this task, but alkylphosphonic acids and derivatives thereof are superior in their effect. 

The sodium salts of these acids, sodium pyrophosphate (Na4 P2 O7) and sodium triphosphate (Nas P3 Oio), have been used widely in detergents. The polyphosphate anions are good additives for cleansing agents because... 

Cyanide blood agents are relatively unstable and tend to polymerize on standing. Polymers can be explosive. Stabilizers or solvents can be added to inhibit decomposition. Stabilizers include phosphoric acid, sulfuric acid, powdered sodium pyrophosphate, and sulfur dioxide. Although cyanide blood agents react with metals, they can be stored in steel or other common containers if stabilized. 

Hall, G.E.M., Vaive, J.E., MacLaurin, A. 1996. Selective leaching of the labile organic component of humus and soils with sodium pyrophosphate solution. In EXTECH I a multidisciplinary approach to massive sulphide research in the Rusty Lake-Snow Lake greenstone belts, Manitoba). Geological Survey of Canada Bulletin, 201-213. 

Pontanen and Morris [8] compared the structure of humic acids from marine sediments and degraded diatoms by infrared and C13 and proton NMR spectroscopy. Samples of marine sediments taken from the Peru continental shelf were extracted with water, sodium hydroxide (0.05mol 1 J) and sodium pyrophosphate (0.05mol l-1) under an atmosphere of nitrogen and fractionated by ultrafiltration. Humic acids of molecular weight 300000 and above were examined. Diatoms were collected from... 

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