Ammonia/nitrate aqueous system

For ammonia-rich aqueous systems the ammonium nitrate calculation is complicated by the dependence of Kp not only on Tand RH but also on the sulfate concentration. This dependence is usually expressed by the parameter Y (Figure 10.21). The parameter Pis the ionic strength fraction of ammonium sulfate and is calculated as... 

Figure 5.22. Tecator Aquatec Analyzer. Designed for determination of ammonia, nitrate, nitrite, and phosphate in aqueous samples, the microprocessor controlled instrument (left)-employs dedicated modules comprising microconduit based Chemifolds and furnished with prepacked reagent solutions (right), facilitating rapid change of function and simplifying the operation of the system.

The monovalent Co chemistry of amines is sparse. No structurally characterized example of low-valent Co complexed exclusively to amines is known. At low potentials and in non-aqueous solutions, Co1 amines have been identified electrochemically, but usually in the presence of co-ligands that stabilize the reduced complex. At low potential, the putative monovalent [Co(cyclam)]+ (cyclam = 1,4,8,11-tetraazacyclotetradecane) in NaOH solution catalyzes the reduction of both nitrate and nitrite to give mixtures of hydroxylamine and ammonia.100 Mixed N-donor systems bearing 7r-acceptor imine ligands in addition to amines are well known, but these examples are discussed separately in Section 6.1.2.1.3. 

The first experiments on chemoautotrophic theory were carried out by Stetter at the University of Regensburg. It was found that synergy in the FeS/H2S system determined the reductive effect, for example, in the conversion of nitrate to ammonia or of alkynes to alkenes. The conditions used corresponded to those present in hydrothermal systems aqueous phase, 373 K, almost neutral pH and anaerobic conditions (Blochl et al 1992). Two years later, the formation of an amide bond without the use of a condensation agent was successfully demonstrated in the same laboratory (Keller et al 1994). 

According to the vendor, this project could provide a compact, low-cost reactor to treat aqueous mixed waste streams containing nitrates or nitrites, eliminate the need for chemical reagents, and minimize or eliminate secondary wastes such as nitrous oxide and secondary products such as ammonia, H2, and O2 that are prevalent with other nitrate destruction processes. By removing nitrates and nitrites from waste streams before they are sent to high-temperature thermal destruction and vitrification, production of NO can be decreased with the attendant decrease in off-gas system requirements. Biocatalytic nitrate destruction is applicable to a wide range of aqueous wastes with a highly variable composition. All information is from the vendor and has not been independently verified. 

Hexammino-iridium Chloride, [Ir(NH3)e]Cl3, is prepared by heating chloro-pentammino-iridium chloride, [Ir(NH3)5Cl]CI2, with 25 per cent, aqueous ammonia in a sealed tube to 140° C. The crude product so obtained is evaporated with hydrochloric acid, the residue dissolved in water, and precipitated by means of sodium pyrophosphate. From this the nitrate is formed by treating with dilute hydrochloric and nitric acids, and finally the nitrate is decomposed by repeated evaporation to dryness with concentrated hydrochloric acid. The residue is then treated with ice-cold hydrochloric acid, when the chloride is precipitated. It crystallises in large six-sided colourless prisms belonging to the monoclinic system, and is soluble in water.1... 

Carbonate op Strontia is found native as stron-tianite, both massive, and in forms belonging to the square prismatic system. It is most readily prepared pure by precipitating the nitrate or chloride with carbonate of ammonia, The artificial carbonate is beautifully white and soluble in one thousand five hundred and thirty-six parts of boiling Water. It is more soluble in aqueous solution of carbonio acid, and separates in needles when, evaporated. Heated to bright redness in a stream of watery vapor it loses its carbonic acid, and becomes changed into strontia. The symbol is SrO, CO Eq. 74-00 specific gravity, 3 605. 

Method. Hie metal chelates are prepared by extracting the metal ion from aqueous solution with 20-, 20- and 10-ml volumes of chloroform after addition of an appropriate amount of a solution of DDTC [0.22S g of the sodium salt in 75 ml of water and 25 ml of an ammonia-ammonium nitrate (1 1) buffer, 3 M in total ammonia]. The exact volumes which are used depend on whether the metal is uni-, bi- or tri-valent. The combined chloroform extracts are diluted to at least 50 ml for chromatography. The metal chelates are separated on plates of silica gel G or N which have been activated at 110 °C for 1 h. The Rp values of a number of DDTC metal chelates in a variety of solvent systems are listed in Table 4.31. The dried plates are sprayed with a solution consisting of 1 10 4A/ Pd(II), 7.0 10 5Af calcein and 0.02Mphosphate buffer [dihydrogen phosphate-hydrogen phosphate (1 1)]. This solution must be allowed to stand for 12 h in order to ensure that equilibrium is attained. For quantitative work with low concentrations, the solution of DDTC should be washed with chloroform before use. This removes fluorescent impurities which may cause interference in the chromatography. 

Absorption Abatement or extended absorption refers to modifications that involve the addition of increased absorption capacity or optimization of the existing absorption system to oxidize and react the nitrogen oxides with water to form acid.. Tail gases are passed through an absorber containing either water or an aqueous solution of ammonia, urea or sodium hydroxide. When water is used as the absorbent, the resultant weak acid is recycled. This increases nitric acid yields by 1% to 3%. When other absorbents are used, the recovered NOx is typically consumed in the production of nitrogen solutions for fertilizer use. If sodium hydroxide is the absorbent, pure sodium nitrite and sodium nitrate may be recovered91,104. 

Semiconductor nanoparticles have been extensively studied in recent years owing to their strongly size-dependent optical properties. Among these nanomaterials, CdS and PbS are particularly attractive due to their nonlinear optical behavior and unusual fluorescence or photoluminescence properties [ 136,137]. A number of studies have been published recently regarding the preparation of CdS, PbS and ZnS nanoparticles in inverse microemulsion systems [138-143]. In these works, NP-5/NP-9 was the most commonly used surfactant and petroleum ether the most commonly used oil. The aqueous phase for each inverse microemulsion consisted of cadmium nitrate (0.1 M) and ammonia sulfide (0.1 M) respectively. CdS was recovered from the mixture of double microemulsions [141]. Electron microscopy revealed that the spherical particles were aroimd 10-20 nm in diameter, as seen in Fig. 14. 

In contrast to SCC of carbon and low-alloy steels in chloride, sulfide, and sulfuric acid environments by hydrogen-embrittlement mechanisms, cracking in several environments is attributed to passive-film cracking and/or active-corrosion-path anodic-dissolution penetration mechanisms (Ref 124). These environments include nitrates, hydroxides, ammonia, carbon-dioxide/carbonate solutions, and aqueous car-bon-monoxide/carbon-dioxide. Nitrate-bearing solutions are encountered in coal distillation and fertilizer plants hydroxide solutions in the production of NaOH and in crevices of steam boilers and ammonia cracking has occurred in tanks and distribution systems for agricultural ammonia applications. 

We also were successful in applying the alkyl nitrate nitration to TT-deficient heterocyclic compounds such as 2- and 4-meth-ylpyridines, 4-methyl pyrimidine, and to ir-excessive heterocyclics such as 2-methylbenzoxazole and 2-methylbenzothiazole (15). Both sodium and potassium amides in liquid ammonia were found to be effective as bases. In the KNH2-JI.NH3 system optimum yields are obtained if the molar ratio of base to substrate to nitrate ester is 2.0 1.0 2.5. After allowing 2-3 minutes for anion formation the nitrate ester is added as rapidly as possible while maintaining the temperature below -33°. Next the ammonia is replaced with ether and the nitro salt filtered off and acidified with aqueous acetic acid. 

Competition between sulfate and nitrate for the available ammonia results in rather complicated system behavior. Addition of ammonium sulfate to solutions containing aqueous ammonium nitrate lowers the ammonia-nitric acid vapor pressure product in equilibrium with the aerosol phase (Figure 9.21). In Figure 9.21, Y is the ionic strength fraction of ammonium sulfate and is calculated as... 

Procedure. Titrate 5 mg of thiol sulphur in 100 ml. of 95 per cent ethanol, containing 0-25 n ammonia and 0-1 N ammonium chloride, at the potential of a saturated calomel electrode (a short circuit system) with an aqueous solution of 0-005 M silver nitrate. Deoxygenate both solutions. 

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