Sodium nitrate Subject

The cmde phthaUc anhydride is subjected to a thermal pretreatment or heat soak at atmospheric pressure to complete dehydration of traces of phthahc acid and to convert color bodies to higher boiling compounds that can be removed by distillation. The addition of chemicals during the heat soak promotes condensation reactions and shortens the time required for them. Use of potassium hydroxide and sodium nitrate, carbonate, bicarbonate, sulfate, or borate has been patented (30). Purification is by continuous vacuum distillation, as shown by two columns in Figure 1. The most troublesome impurity is phthahde (l(3)-isobenzofuranone), which is stmcturaHy similar to phthahc anhydride. Reactor and recovery conditions must be carefully chosen to minimize phthahde contamination (31). Phthahde [87-41-2] is also reduced by adding potassium hydroxide during the heat soak (30). 

The behaviour of americium and curium in soil has been the subject of very few investigations. Hajek (42) observed that water and sodium nitrate (1 m) extracted americium from the soil to the extent of 7.5 % and 33% respectively. As noted earlier Knoll (40) extracted 100% of the americium in soil. 

The reduction of nitrate to nitrite can be accomplished satisfactorily, and the process is the subject of a recent patent.1 It has been shown (Mtlller and Weber)2 that in a divided cell, smooth platinum or copper cathodes reduce nitrate to nitrite and ammonia, but platinised platinum gives much ammonia and little nitrite. A spongy copper or silver cathode was found to give the best results. With a current density of 0 25 amps, per dm.2 and a concentration of 2 3 grams of sodium nitrate per litre, a current efficiency of 90 per cent, was obtained. The current efficiency with an amalgamated copper cathode was found to diminish when 50 per cent, of the nitrate had been changed. Considerable care is evidently needed to prevent the formation of ammonia, since it has been shown by W. H. Easton 3... 

In order to generalize the definition of the solvent system for the case of ionic media, we shall analyse Franklin s definition. First, it should be noted that the term auto-ionization in this definition should be substituted by auto-dissociation or intrinsic acid-base equilibrium of the solvent , as a more common case of heterolytic break down of the constituent particles of a liquid. Indeed, for molecular solvents or those which are slightly ionized at room temperature, the terms autoionization and intrinsic acid-base equilibrium of the solvent , relate to the same process, whereas for ionic liquids they differ considerably. For example, although sodium nitrate (NaNOs) is subject to practically... 

There have been a number of publications on determination of column void-volume (30-35) and this subject is still one of the hot topics in LC. From our knowledge and basic study on this subject(36, 37), we decided sodium nitrite and sodium nitrate are good solutes to measure column void-time in reversed-phase LC. Therefoi, the elution time of sodium nitrite was used as t in this work. Its concentration used was c.a. 100 ppm in each mobile phase. 

In 1761 the mineral that disturbed the tin production was subjected to chemical examination. J. G. Lehmann, known from the history of the chromium discovery, investigated a wolframite from Zinnwald (Cinovec in today s Czech Repubhc). When he melted the mineral sample in sodium nitrate, leached it in water and added hydrochloric acid he observed a white precipitate that gradually became yellow. He had in fact seen tungstic acid, but did not reahze that there was a new element in it. 

Ferrous Sulfdte Titration. For deterrnination of nitric acid in mixed acid or for nitrates that are free from interferences, ferrous sulfate titration, the nitrometer method, and Devarda s method give excellent results. The deterrnination of nitric acid and nitrates in mixed acid is based on the oxidation of ferrous sulfate [7720-78-7] by nitric acid and may be subject to interference by other materials that reduce nitric acid or oxidize ferrous sulfate. Small amounts of sodium chloride, potassium bromide, or potassium iodide may be tolerated without serious interference, as can nitrous acid up to 50% of the total amount of nitric acid present. Strong oxidizing agents, eg, chlorates, iodates, and bromates, interfere by oxidizing the standardized ferrous sulfate. 

In most cases, the impregnation process is followed by an electrochemical formation where the plaques are assembled into large temporary cells filled with 20—30% sodium hydroxide solution, subjected to 1—3 charge—discharge cycles, and subsequentiy washed and dried. This eliminates nitrates and poorly adherent particles. It also increases the effective surface area of the active materials. 

The choice of the anion ultimately intended to be an element of the ionic liquid is of particular importance. Perhaps more than any other single factor, it appears that the anion of the ionic liquid exercises a significant degree of control over the molecular solvents (water, ether, etc.) with which the IL will form two-phase systems. Nitrate salts, for example, are typically water-miscible while those of hexaflu-orophosphate are not those of tetrafluoroborate may or may not be, depending on the nature of the cation. Certain anions such as hexafluorophosphate are subject to hydrolysis at higher temperatures, while those such as bis(trifluoromethane)sulfonamide are not, but are extremely expensive. Additionally, the cation of the salt used to perform any anion metathesis is important. While salts of potassium, sodium, and silver are routinely used for this purpose, the use of ammonium salts in acetone is frequently the most convenient and least expensive approach. 

A method of separation which avoids the preparation of the double fluorides consists in fusing the mixed niobic and t an tali c acids with sodium carbonate and nitrate, the product is digested with warm water and a current of carbon dioxide is passed through the solution. It is claimed that only tantalic acid is precipitated.5 This process has, however, been the subject of adverse criticism.6 Partial separation of niobium from tantalum can be effected by warming the mixed, freshly precipitated, hydrated oxides with a mixture of hydrogen peroxide and hydrochloric acid the niobium dissolves readily, while the tantalum dissolves only sparingly.7... 

Ferric orthoarsenite cannot be prepared directly from ferric hydroxide and arsenious oxide.4 The brown product obtained by shaking freshly precipitated ferric hydroxide with an aqueous solution of arsenious oxide has been described 5 as a basic ferric arsenite of composition 4Fe203.As203.5H20. A similar substance is obtained by adding aqueous arsenious oxide or sodium arsenite to ferric acetate solution. If ferric chloride, sulphate or nitrate is used, the ferric salt is not completely precipitated. The product is oxidised in moist air, and decomposes when heated. It is very doubtful whether this is a chemical individual, however, for it has been shown that the removal of arsenious oxide from the solution by the ferric hydroxide is due to adsorption, the amount removed depending upon the conditions and the age of the adsorbent. This subject is discussed more fully on p. 154. 

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