Ammonia release

For most crops, other than rice, urea in the soil must first undergo hydrolysis to ammonia and then nitrification to nitrate before it can be absorbed by plant roots. One problem is that in relatively cool climates these processes are slow thus plants may be slow to respond to urea fertilization. Another problem, more likely in warmer climates, is that ammonia formed in the soil hydrolysis step may be lost as vapor. This problem is particularly likely when surface appHcation is used, but can be avoided by incorporation of the urea under the soil surface. Another problem that has been encountered with urea is phytotoxicity, the poisoning of seed by contact with the ammonia released during urea hydrolysis in the soil. Placement of urea away from the seed is a solution to this problem. In view of the growing popularity of urea, it appears that its favorable characteristics outweigh the extra care requited in its use. 

In the semidirect process, (Fig. 23) the taw coke oven gas is cooled to condense tar and ammonia Hquor. The heavy layer, tar phase, is pumped to storage and the aqueous layer containing free and fixed ammonia is subsequendy processed in a stiH operation. Free ammonia is that which is in a form which readily dissociates by heat. Fixed ammonia is in a form which requites the presence of an alkaH, such as milk of lime, to effect the ammonia release. 

Ammonia Plants - New ammonia plants should set as a target the achievement of nitrogen oxide emissions of not more than 0.5 kg/t of product (expressed as NOj at 3%). Ammonia releases in liquid effluents can be controlled to 0.1 kg/t of product. Condensates from ammonia produetion should be reused. 

The team suggested mitigations. For example, the consequences of an ammonia release could be markedly reduced by a reliable and quick-acting water spray system. The probability of damage due to ship collisions could be reduced by a f tor of five by a speed limit of eight knots. Evacuation of the potentially affected is practicable and effective. 

A release category is a grouping of specific types of releases with similar chaiacteristics. Here, two general types of ammonia release were defined ... 

Certain internal chemical treatments employed also need strict control to avoid risks of adverse chemical reaction and resultant corrosion. In particular, nitrogen-containing chemicals such as hydrazine and amines require effective monitoring to limit the concentration of ammonia release into steam because the presence of ammonia may, under certain conditions, cause stress corrosion cracking of copper and brasses. 

The Haber reaction for the formation of ammonia releases energy ... 

Another characteristic of this solution is its proneness to crystallization and polymerization. When parts of the exhaust system are constantly welted by Adblue on the same spot, undesired urea crystals or polymers may form if the exhaust line temperature is lower than 300°C. This phenomenon will result in uncontrolled ammonia production when the crystals or polymers melt or sublimate after being heated at significantly higher temperatures (T > 350°C). This may result in ammonia release. Furthermore, the crystals or polymers can also have an impact on the SCR catalyst cells by reducing the catalyst surface and thus reducing the catalyst performances. 

While for the as-synthesized sample, after the fulfilling of dehydration, no further volume variation is observed, for the exchanged phase after the ammonia release, the cell volume contraction rate quickly increases leading to a final volume decrease of 3.82%. This could be the consequence of the larger voids left in the channels of the latter phase, where, only protons are left in the channels of the dehydrate NH4-form. 

The proteins in the mortars can be modified by gradual oxidation or other chemical processes. In mass spectra the peaks that can be interpreted as oxygen incorporation (the mass shift of +16 Da) or ammonia release (—15 Da) can be sometimes indicated. This observation is not surprising as several amino acids (Met, Trp, Tyr, etc.) can be oxidised under these conditions similarly, Gin and Asn can gradually release their ammonia by long-term hydrolysis in a wet inorganic matrix. 

The baking process has remained much the same until the present day at a stoichiometric ratio of 1 4, phthalic anhydride or phthalic acid reacts with an ammonia releasing compound. The reaction may also start from other suitable materials, such as phthalic acid derivatives, including phthalic acid esters, phthalic acid diamide, or phthalimide. Appropriate ammonia releasing agents include urea and its derivatives, such as biuret, guanidine, and dicyanodiamide. The fact that a certain amount of urea decomposes to form side products makes it necessary to use excess urea. Approximately 0.2 to 0.5, preferably 0.25 equivalents of copper salt should be added for each mole of phthalic anhydride. 0.1 to 0.4 moles of molybdenum salt per mole of phthalic anhydride is sufficient. The reaction temperature is between 200 and 300°C. 

In 1927, Van Slyke devised a micromethod using urease. Instead of determining ammonia released by alkali from ammonium carbonate, carbon dioxide was liberated after acidification. This was successfully... 

ELLIOT, H.A. and COLLINS, N.E. Factors affecting ammonia release in broiler houses. 1982—Transactions of the ASAE. p. 413-419. 

British-American Tobacco (1988) Nicotine scavenging-A consequence of ammonia-release taste modifier no. 7. http //tobaccodocuments.org/product design/402363924-3962.html British American Tobacco (1994) Proceedings of chemosensory meeting held in Southampton 8-10 Nov 1993. 16 Feb 1994. Bates 570354096-570354354. http /Aobaccodocuments.org/ product design/954103.html... 

An interesting possibihty, never investigated, is that the bear possesses the ability to synthesise both dispensable and non-dispensable amino acids de novo, from the ammonia released by the microorganisms. As far as is known, no mammal possesses the enzymes necessary to synthesise the indispensable amino acids. It would be interesting if another adaptation to such a long hibernation is development of enzymes necessary to synthesise indispensable amino acids. This possibility is supported by the... 

Solid solutions of fluorhydroxyapatite (Caio(P04)6(OH)2-x(F)x) can be prepared at high temperatures by gaseous fluoridation of HA powder this leads to water and ammonia release, as follows [115] ... 

In acid solution, cobalt(III) ammines are unstable with respect to reduction of the metal center to cobalt(II). The potential for the reduction shown in reaction (11) is about 1.8 V, but most of the energy difference is due to the protonation of the ammonias released by cobalt(II) which is a labile d1 system. 

When acido groups, halides, thiocyanate, azide, acetate, and nitrate are present in the coordination sphere of cobalt(III), they appear to be oxidized in preference to coordinated ammonia. Many of the radicals thus produced are capable of oxidizing ammonia released from the complex or of interfering in other ways with the reduction process, and these systems have proved very difficult to understand even in general terms. Quantum yield and other data for a number of acidopentammine and certain other complexes are given in Table IV the data on the aquation reactions of some of the complexes are considered in Section I1I-D. 

The final piece of the puzzle is the placement of the mole of ammonia released from the original peptide on acid hydrolysis. The ammonia comes from a primary amide function ... 

FIGURE 14.32 When anhydrous aluminum chloride is left exposed to moist air, it reacts to form hydrochloric acid. Here white fumes of ammonium chloride form as the hydrochloric acid reacts with ammonia released in the vicinity. 

A multicomponent positive-imaging process using ammonia release has been described by Ricoh.211 The components of the system are (1) a cobalt(III) hexaammine complex, (2) a quinone photoreductant, (3) a chelating agent such as dimethylglyoxime, (4) a leuco dye (triarylmethane type), (5) a photooxidant (biimidazole) and (6) an organic acid (toluenesulfonic acid). 

Zhang RH, Day DL, Christianson LL, Jepson WP (1994) A computer-model for predicting ammonia release rates from swine manure pits. J Agric Eng Res 58 223-229... 

The rubber or plastic outlet tube should be depression-free and lead via an adapter into the receiver flask (see below) which must be sited in the fume cupboard, and it is advised that this delivery tube be additionally supported by means of a retort stand and clamp. This latter precaution is necessary since the initial force of ammonia release may cause it to flex with considerable thrust which may lead to apparatus damage. 

HMSO (UK) [17] have published a method for the determination of ammonia, nitrate and nitrite in potassium chloride extracts of soil extracts. An aliquot of the extract is made alkaline and the ammonia released, originating from ammonium ions, is determined either with an ammonia-selective probe or, after removal by distillation, by titration (Crompton TR, private communication). 

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