Nitrate salt oxidation process

Molten Nitrate Salt Oxidation Process (10). The reaction of UO2 with molten nitrate salts to form uranates that are sub-sequently reduced to effect a separation of the uranium is being evaluated. The actinide behavior and uranate composition in equimolar sodium-potassium nitrate is being studied to determine the uranate stability and forecasting of cation behavior in subsequent process steps. 

Approximately 45% of the world s phthaUc anhydride production is by partial oxidation of 0-xylene or naphthalene ia tubular fixed-bed reactors. Approximately 15,000 tubes of 25-mm dia would be used ia a 31,000 t/yr reactor. Nitrate salts at 375—410°C are circulated from steam generators to maintain reaction temperatures. The resultant steam can be used for gas compression and distillation as one step ia reduciag process energy requirements (100). 

The major problem of these diazotizations is oxidation of the initial aminophenols by nitrous acid to the corresponding quinones. Easily oxidized amines, in particular aminonaphthols, are therefore commonly diazotized in a weakly acidic medium (pH 3, so-called neutral diazotization) or in the presence of zinc or copper salts. This process, which is due to Sandmeyer, is important in the manufacture of diazo components for metal complex dyes, in particular those derived from l-amino-2-naphthol-4-sulfonic acid. Kozlov and Volodarskii (1969) measured the rates of diazotization of l-amino-2-naphthol-4-sulfonic acid in the presence of one equivalent of 13 different sulfates, chlorides, and nitrates of di- and trivalent metal ions (Cu2+, Sn2+, Zn2+, Mg2+, Fe2 +, Fe3+, Al3+, etc.). The rates are first-order with respect to the added salts. The highest rate is that in the presence of Cu2+. The anions also have a catalytic effect (CuCl2 > Cu(N03)2 > CuS04). The mechanistic basis of this metal ion catalysis is not yet clear. 

Subcategory A encompasses the manufacture of all batteries in which cadmium is the reactive anode material. Cadmium anode batteries currently manufactured are based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples (Table 32.1). The manufacture of cadmium anode batteries uses various raw materials, which comprises cadmium or cadmium salts (mainly nitrates and oxides) to produce cell cathodes nickel powder and either nickel or nickel-plated steel screen to make the electrode support structures nylon and polypropylene, for use in manufacturing the cell separators and either sodium or potassium hydroxide, for use as process chemicals and as the cell electrolyte. Cobalt salts may be added to some electrodes. Batteries of this subcategory are predominantly rechargeable and find application in calculators, cell phones, laptops, and other portable electronic devices, in addition to a variety of industrial applications.1-4 A typical example is the nickel-cadmium battery described below. 

V,/V-Bis(trifluoromethyl)hydroxylamine (5) is oxidized with potassium permanganate in acetic acid to an interesting free-radical compound, bis(trifluoromethyl)nitroxid-A7-yl(6), a pink-violet gas which condenses to a deep brown-violet liquid.246 Various oxidizing agents are effective in the oxidation of 5 to the corresponding nitroxyl 6.247 The best appears to be cerium(IV) salts either in the solid state or in aqueous acid solution.247 Efficient oxidation processes have been developed using aqueous potassium persulfate solutions, or electrochemical oxidation with cerium(III) nitrate and sodium nitrate in dilute nitric acid.247... 

A methyl group present in the ring facilitates the introduction of nitro groups. This is why m- cresol is more readily nitrated than phenol. On the other hand a methyl group enhances oxidation processes. This accounts for the lower yield of trinitro-cresol obtained, as compared with that of picric acid. Like picric acid, trinitrocresol has the disadvantage of readily forming metallic salts which are sensitive to impact. 

The processes by which clouds incorporate sulfuric and nitric acids are conveniently distinguished into two categories depending upon whether oxidation takes place in the gas phase or in the aqueous phase, as illustrated schematically in Figure 1. For an examination of gas-phase atmospheric oxidation of SO2 and NO2 see (1,2). Products of this oxidation, aerosol sulfuric acid and sulfat and nitrate salts, and gas-phase nitric acid, are expected to be rapidly and to great extent incorporated into cloud droplets upon cloud formation 0,4). 

The most common salt mixture used is a eutectic blend of 40% sodium nitrite, 7% sodium nitrate, and 53% potassium nitrate. Its temperature range is from 150°C to 540°C. The melting point of a fresh mixture of this salt composition is 142°C. However, sodium nitrite slowly undergoes endothermic breakdown to form sodium nitrate, sodium oxide, and nitrogen. Nitrite can also undergo oxidation to form nitrate. This process results in the increase of its melting point. It can react with carbon dioxide to form carbonates and with water to form hydroxides. 

Usually efficient systems to remove HCN contain copper and an oxidizing salt such as sodium dichoromate [94]. Copper, either from nitrate or oxide is reduced to metal, then the oxidizing agent is added. Since the mixture is expected to exist in mesopores, they are active in the adsorption—chemisorption process. The chemistry of reactions in such systems was proposed by Alves and Clark [94]. It occurs in two stages ... 

The RH in most indoor environments is usually not above 70 percent and, thus, the CRH of most common metals is seldom exceeded. The time-of-wetness will be quite small. The corrosion rate is likely to be comparable to the outdoor rate (at similar contaminant levels) when the surfaces are dry. Such rates are insignificant compared to the wet rates for most metals (18). In many cases, the anions associated with deposited substances may play the dominant role in surface processes (24). The concentrations of sulfate, nitrate, and chloride, which accumulate on these surfaces, are likely to increase continuously. After 10 years exposure, total anion concentrations of five to ten /ng/cm can be expected in urban environments. These anions, especially chloride, are well known to dramatically affect the corrosion rates of many metals in aqueous solutions. This acceleration is often a result of solubilization of the surface metal oxide through complexation of the metal by the anions. Chloride, in particular, can dramatically lower the RH above which a moisture film is present on the surface, since chloride salts often have low CRHs (e.g., zinc chloride - < 10 percent calcium chloride - 30 percent and aluminum chloride - 40 percent). The combination of the low CRHs of chloride salts and the well documented ability of dissolved chloride to break down metal oxide passivation set chloride apart from the other common anions in ability to corrode indoor metal surfaces. Some nitrate salts also have moderately low CRHs (e.g., zinc nitrate -38 percent calcium nitrate - 49 percent aluminum nitrate - 60 percent). 

It is well known that, after its absorption, NOz forms nitric acid and nitrous acid in water. There is some indication that nitrite produced in this way is oxidized by dissolved 03 (Penkett, 1972). If neutralizing agents (ammonia, calcium carbonate etc.) are present, some nitrate salt is finally formed. It follows from this discussion that both S02 and N02 are oxidized in cloud water by atmospheric ozone. If this speculation is true a correlation should be found between the concentration of sulfate and nitrate ions in precipitation waters. Such a correlation was found in precipitation samples by Gambell and Fisher (1964) among others. However, correlations between any two species in rainwater must be considered with caution because the level of all ions is affected in a similar way by the precipitation intensity or quantity (see Subsection 5.4.1). Nevertheless the identical annual variations of the two ions in precipitation water (see Subsection 5.4.5) suggests that the two species are formed by some similar processes. 

In the determination of benzene, interfering effects of dinitrotoluene and dinitroxylenes originating from toluene and xylenes are removed by oxidation of methyl groups with a chromic acid solution. Dinitrobenzene is stable during this oxidation process. After adding pyridine and alkalization of the diluted nitration mixture, the two layers are separated from each other. Sodium salts of nitrocarbonic acids formed by the oxidation remain in the aqueous layer, whereas m-dinitrobenzene passes into the pyridine layer. The pyridine layer is separated, methyl ethyl ketone is added and the red-violet colour is evaluated by photometry [18]. 

This unfavorable effect of low pH is usually intensified by the nitrogen fertilizers themselves, because most of them increase soil acidity. This may be due to the added acid, as in the case of S04 in ammonium sulfate. It may also be due to the NOs added as neutral salts, or to that formed in the nitrification process. If the NOs formed by nitrification is assimilated by plants and converted into protein, there is no appreciable direct effect on soil pH, but if the acid is leached out in the form of nitrate salts then the increase in soil acidity is marked. Even anhydrous ammonia, which is strongly basic, will produce acidity to the extent that it is nitrified and lost to the drainage waters as calcium nitrate or as some other neutral salt. Even if biologically-fixed nitrogen, present in plants as protein, undergoes decomposition to ammonia and oxidation to nitrate, it increases acidity if leaching occurs. Most of the increase in soil acidity is due to the removal of bases as nitrate salts. The possible reactions are explained in detail by Allison (1931). 

The reduction reactions of species related to biological activities, such as nitrates, manganese oxides, ferrous salts, and sulfates to sulfide, and the reduction of carbon compounds to methane, although the cathodic process can also be sustained by stray currents... 

ESR spectra of nitric oxide (NO) and nitrogen dioxide (NO2) radicals trapped in micro-voids of the solid were observed when the N-T102 samples were prepared and treated in different ways the ESR parameters are listed in Table 6.4. The NO radical was found to be a product of the complex oxidation process of ammonium salts occurring upon calcinations of the solid. NO2 was formed only when nitrates or nitric acid were used as nitrogen source and could be thus considered to derive from their decomposition. Due to their nature of the trapped species, it is concluded that both NO and NO2 do not directly influence the electronic structure of the system. 

The cheapest type of nitrate-to-oxide conversion process, based upon thermal denitration, has been shown in Fig. 9.3. This can be carried out in a simple batch type of pot denitrator or in more elegant continuous plant for larger scale production. If a little iron impurity is introduced, the molten salt electrolysis stage which follows allows an opportunity for purification again before the metal powder is produced. 

The counterflow extraction process was carried out in stainless steel equipment and used column cascade extraction technology. The aqueous feed consisted primarily of nitric acid that contained the FPs and TRU elements as nitrate salts. The plutonium was oxidized to the hexavalent state with Na2Cr207. The aluminum nitrate salting agent is added, after... 

Nitrate stock solution This solution is made close to the solubility of the nitrate salt (5 mol/L). Contaminating chromium in the concentrated nitrate solution is removed by coprecipitation with iron(ni)hydroxide. Iron(//f) chloride (final concentration 0.1 mmol/L) is thus added and allowed to become oxidized by dissolved oxygen. This is filtered off to produce the purified nitrate solution this process reduces chromium(V7) to chromium(///) which adsorbs on the iron(lII)hydroxide and is removed. Most conveniently the acetate buffer is premixed with the nitrate solution (to a final concentration of 0.2 mol/L acetate in 5 moI/L nitrate) and purified simultaneously. Thus the overall chromium reagent blank is typically reduced to less than 0.03 nmol/L. 

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