Nitric acid high-purity

Table 8.4 Effect of washing grape with 2% nitric acid high purity water solution. Median values are given (n.s. = not significant = p < 0.05 = p < 0.001).

Fuming nitric acid, high purity. Purify nitric acid, 90% (J. T. Baker) by sub-boiling distillation from a Teflon still prior to use. 

The metal is not attacked by hydrochloric acid, nor does it react with dilute nitric and sulfuric acids. High purity selenium reacts slowly with concentrated nitric acid. The crude metal, however, dissolves in cold concentrated nitric acid. 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

The manufacture of silver nitrate for the preparation of photographic emulsions requires silver of very high purity. At the Eastman Kodak Company, the principal U.S. producer of silver nitrate, 99.95% pure silver bars are dissolved in 67% nitric acid in three tanks coimected in parallel. Excess nitric acid is removed from the resulting solution, which contains 60—65% silver nitrate, and the solution is filtered. This solution is evaporated until its silver nitrate concentration is 84%. It is then cooled to prepare the first crop of crystals. The mother Hquor is purified by the addition of silver oxide and returned to the initial stages of the process. The cmde silver nitrate is centrifuged and recrystallized from hot, demineralized water. Equipment used in this process is made of ANSI 310 stainless steel (16). 

Arsenic trioxide may be made by burning arsenic in air or by the hydrolysis of an arsenic trihaUde. Commercially, it is obtained by roasting arsenopyrite [1303-18-0] FeAsS. It dissolves in water to a slight extent (1.7 g/100 g water at 25°C) to form a weaMy acidic solution which probably contains the species H AsO, orthoarsenous acid [36465-76-6]. The oxide is amphoteric and hence soluble in acids and bases. It is frequendy used as a primary analytical standard in oxidimetry because it is readily attainable in a high state of purity and is quantitatively oxidized by many reagents commonly used in volumetric analysis, eg, dichromate, nitric acid, hypochlorite, and inon(III). 

Silver [7440-22-4]—The coloi additive silvei (EEC No. E 174) is a crystaUine powdei of high purity silver prepared by die reaction of silver nitrate with ferrous sulfate in the presence of nitric, phosphoric, and sulfuric acids. Poly(vinyl alcohol) is used to prevent the agglomeration of crystals and the formation of amorphous silver. 

Suberic Acid. This acid is not produced commercially at this time. However, small quantities of high purity (98%) can be obtained from chemical supply houses. If a demand developed for suberic acid, the most economical method for its preparation would probably be based on one analogous to that developed for adipic and dodecanedioic acids air oxidation of cyclooctane to a mixture of cyclooctanone and cyclooctanol. This mixture is then further oxidized with nitric acid to give suberic acid (37). 

Nitric acid plants Tantalum heat exchangers and sparge pipes find extensive use in plants producing high purity nitric acid, ammonium nitrate and terephthalic acid. 

Oxidation of 4-methylcyclohexanone by addition of nitric acid at about 75°C caused a detonation to occur. These conditions had been used previously to oxidise the corresponding alcohol, but although the ketone is apparently an intermediate in oxidation of the alcohol, the former requires a much higher temperature to start and maintain the reaction. An OTS report, PB73591, mentions a similar violent reaction with cyclohexanone [1], Presence of nitrous acid is essential for the smooth oxidation of cycloalkanones with nitric acid to a, rw-hcxanedioic acids. Because high-purity nitric acid (free of nitrous acid) is now commonly available, addition of a little sodium or potassium nitrite to the acid is necessary before its use to oxidise cycloalkanones [2],... 

For example, the industrial preparation of mineral acids, such as sulfuric, hydrochloric and nitric, inevitably leads to them containing small concentrations of metals as impurities. If the acid is to be used purely as an acid in a simple reaction, the presence of small amounts of metals is probably unimportant. If, however, the acid is to be used to digest a sample for the determination of trace metals by atomic absorption spectrometry, then clearly the presence of metallic impurities in the acid may have a significant effect on the results. For this latter application, high-purity acids that are essentially metal-free are required. 

Exists in two adotropic modifications. Crystalline sihcon is made up of grayish-black lustrous needle-hke crystals or octahedral platelets cubic structure Amorphous sdicon is a brown powder. Other physical properties are density 2.33g/cm3 at 25°C melts at 1,414°C high purity liquid silicon has density 2.533 g/cm at its melting point vaporizes at 3,265°C vapor pressure 0.76 torr at 2,067°C Mohs hardness 6.5. Brinell hardness 250 poor conductor of electricity dielectiric constant 13 critical temperature 4°C calculated critical pressure 530 atm magnetic susceptibility (containing 0.085%Fe) 0.13x10 insoluble in water dissolves in hydrofluoric acid or a mixture of hydrofluoric and nitric acids soluble in molten alkalies. 

In order to produce MF of quality complying with requirements of US Military Specification JAN-M-219, all raw materials mercury, nitric acid and ethanol should be of high purity Procedure... 

According to White [38a], nitrosation involving the use of dinitrogen tetroxide ( nitrogen tetroxide ) represents the most general method of nitrosating amides. The method is quite rapid, yields are high, and purity of products is excellent. Since nitric acid is a coproduct of the reaction, the normal procedure involves the use of an excess of anhydrous sodium acetate as a base. If the base is not added, dinitrosation takes place. 

The collection and preparation of water samples requires individual approaches for different analytical tasks. If heavy metals or long-lived radionuclides at the trace and ultratrace concentration range are to be determined in water samples by ICP-MS, especially careful sampling is necessary to avoid possible contamination (using clean bottles and containers washed and cleaned before use, for example, with 2 % nitric acid and high purity water to stabilize traces in the samples), and the loss of analyte by adsorption effects or precipitation should be also considered. 

T. Urbanski and Semenczuk found that tetryl prepared with nitric acid alone is of high purity, possibly because it is not contaminated with 2,4,6-f.initro-N-methyl-aniline formed from tetryl as a result of the loss of the N-nitro group on heating with sulphuric acid, present in an ordinary nitrating mixture. 

In tlie PUREX process, the spent fuel and blanket materials are dissolved in nitric acid to form nitrates of plutonium and uranium. These are separated chemically from the other fission products, including the highly radioactive actinides, and then the two nitrates are separated into tv/o streams of partially purified plutonium and uranium. Additional processing will yield whatever purity of the two elements is desired. The process yields purified plutonium, purified uranium, and high-level wastes. See also Radioactive Wastes in the entry1 on Nuclear Power Technology. Because of the yield of purified plutonium, the PUREX process is most undesirable from a nuclear weapons proliferation standpoint,... 

---