Showing papers on "Ammonia published in 1975"
TL;DR: A critical evaluation of the literature data on the ammonia–water equilibrium system has been carried out and results of calculations of values of pKa at different temperatures and of percent of NH3 in aqueous ammonia solutions of zero salinity as a function of pH and temperature are presented.
Abstract: The toxicity of ammonia to fishes has been attributed to the un-ionized ammonia chemical species present in aqueous solution Because the percent of total ammonia present as un-ionized ammonia (NH3) is so dependent upon pH and temperature, an exact understanding of the aqueous ammonia equilibrium is important for toxicity studies A critical evaluation of the literature data on the ammonia–water equilibrium system has been carried out Results of calculations of values of pKa at different temperatures and of percent of NH3 in aqueous ammonia solutions of zero salinity as a function of pH and temperature are presented
1,329 citations
01 Jan 1975
TL;DR: In this paper, the reaction rates of formation of NO and N2 were determined from measurements carried out on flat premixed hydrocarbon/oxygen argon (or helium) flames, into which small amounts of ammonia, or cyanogen are added.
Abstract: From measurements carried out on flat premixed hydrocarbon/oxygen argon (or helium) flames, into which small amounts of ammonia, or cyanogen are added, overall reaction rates of formation of NO and N2 are determined. From similar measurements effected on nitrogen-diluted ethylene/oxygen flames, an overall rate of prompt NO formation is obtained. The discussion of these rate constants indicates that the relative importance of HCN molecules as intermediates in the fuel NO mechanism increases according to the following sequence of primary fuel nitrogen compounds: ammonia, cyanogen and molecular nitrogen; this last is found to behave like a true fuel nitrogen compound in the early flame stages. Experimental values of the total yield of nitric oxide obtained from the added nitrogen compounds have been determined; they are found to be in good agreement with yields calculated by numerical integration of the empirical overall reaction rates of NO and N2 formation, showing almost the same dependence of the NO yield on temperature, initial fuel nitrogen concentration and oxygen concentration.
537 citations
TL;DR: In this article, the infrared spectra of ammonia adsorbed on CoO, NiO, SiO 2, CaO, MgO, ZrO2, ZnO, TiO 2, BeO and Al 2 O 3, have been studied in the NH stretching and bending vibration regions at various stages of sample dehydroxylation.
229 citations
TL;DR: THE AUTHORS have reduced ligating molecular nitrogen (dinitrogen) to ammonia in yields of up to 90% at a single metal site and this reaction was performed in a vacuum so that the evolved gases could be analysed and measured.
Abstract: WE have reduced ligating molecular nitrogen (dinitrogen) to ammonia in yields of up to 90% at a single metal site This reaction is important for its possible application to our understanding of the chemical mechanism of the reduction of dinitrogen to ammonia by nitrogenase, where the reduction may occur at a single molybdenum ion site1 Our reaction occurs when compounds of the type [M(N2)2(PR3)4](I; M =Mo or W; R = alkyl or aryl) are treated at room temperature with sulphuric acid in methanol solution: This reaction was performed in a vacuum so that the evolved gases could be analysed and measured On mixing the reagents, one molecule of nitrogen gas was rapidly evolved with a trace of dihydrogen The remaining dinitrogen was spontaneously reduced to ammonia together with some hydrazine, presumably also with concomitant oxidation of the metal M
216 citations
177 citations
TL;DR: The data suggest that both the rate of of energy production and the rates of generation of reducing equivalents from endogensou substrates are insufficient to meet the requirements for optimal rates of urea synthesis.
174 citations
TL;DR: On Fe MgO catalysts with metallic iron particles between 1.5 and 30 nm, the ammonia synthesis at atmospheric pressure and between 570 and 680 K was found to be a structure sensitive reaction with the turnover number of the small particles being an order of magnitude smaller than that for larger particles as discussed by the authors.
143 citations
TL;DR: Methylamine (methylammonium ion) entered Saccharomyces cerevisiae X2180-A by means of a specific active transport system and was a strong competitive inhibitor of methylamine uptake, whereas other amines inhibited to a much lesser extent.
Abstract: Methylamine (methylammonium ion) entered Saccharomyces cerevisiae X2180-A by means of a specific active transport system. Methylamine uptake was pH dependent (maximum rate between pH 6.0 and 6.5) and temperature dependent (increasing up to 35 C) and required the presence of a fermentable or oxidizable energy source in the growth medium. At 23 C the vmax for methylamine transport was similar 17 nmol/min per mg of cells (dry weight) and the apparent Km was 220 muM. The transport system exhibited maximal activity in ammonia-grown cells and was repressed 60 to 70 percent when glutamine or asparagine was added to the growth medium. There was no significant derepression of the transport system during nitrogen starvation. Ammonia (ammonium ion) was a strong competitive inhibitor of methylamine uptake, whereas other amines inhibited to a much lesser extent. Mutants selected on the basis of their reduced ability to transport methylamine (Mea-R) simultaneously exhibited a decreased ability to transport ammonia.
127 citations
TL;DR: In this article, an investigation of the effects of ozone on ammonia in municipal wastewaters is described and discussed relative to the application of ozone for advanced waste treatment, which is especially attractive in conjunction with lime clarification and precipitation of phosphate.
89 citations
TL;DR: A dilution method for avian urine and modified existing analytical methods for ammonia, urea, uric acid and total nitrogen to permit determination of all these compounds on aliquots of the same urine sample consistent for four different dietary protein-water availability regimes.
88 citations
TL;DR: Results from published experiments dealing with several aspects of nitrogen utilization by ruminants were used to test the concept of zero utilization of nonprotein nitrogen under conditions where more ammonia is in the rumen than can be converted to microbial protein.
TL;DR: Urea synthesis was studied using the isolated liver perfusion with ammonium cholride and glutamine as nitrogen sources and a marked additive effect on the rate of urea formation was observed with the combined addition of ornithine and N-acetylglutamate.
Abstract: Urea synthesis was studied using the isolated liver perfusion with ammonium cholride and glutamine as nitrogen sources. The rate of urea formation increases with ammonium cholorde concentration up to 5mM, and the rate remained constant in the range between 5 and 20mM of ammonium chloride as the substrate. The concentration of ammonia in the medium to support the half-maximum velocity of urea formation was 0.7mM. The rate of urea formation was stimulated by the addition of 2.5mM ornithine, and the greater part of the ornithine which was taken up into the liver was accumulated as citrulline in the presence of ammonia. A considerable accelerating effect of N-acetylglutamate on the synthetic rate was observed, but a rather high concentration of N-acetylglutamate was required in order to obtain the maximum effect possibly, because its permeability into liver cells may be limited. A marked additive effect on the rate of urea formation was observed with the combined addition of ornithine and N-acetylglutamate. The metabolic conversion of glutamine nitrogen to urea in the perfused rat liver and the effect of several compounds which stimulated urea synthesis with ammonia were further examined. The process of conversion of glutamine nitrogen to urea might be composed of the following three steps. In the first lag phase, a small amount of glutamine was removed from the medium. In the second stage, the glutamine level decreased rapidly and ammonia was accumulated in the perfusate. The third stage was a period in which glutamine concentration remained at a constant low level, and the accumulated ammonia was rapidly conversed to urea. The rate of urea formation in this third stage was found to be much higher than that with ammonia as the substrate. The maximum rate of glutamine removal was obtained at pH 7.7 of the perfusate and at a concentration of 10mM glutamine. Urea formation with glutamine was also stimulated by the addition of ornithine, malate, or N-acetylglutamate, which had accelerating effects on the urea synthesis with ammonia. This stimulation was due to an effective conversion of ammonia to urea, but no change in the rate of removal glutamine was obtained.
Patent•
09 Jul 1975
TL;DR: In this article, the aqueous ammonia derived from the separation stage is heated by free steam under a lowered pressure to free ammonia in gaseous form, then mixed with conventionally dried sludge to increase the nitrogen content of the sludge from approximately 1-2 percent to as high as 10 percent.
Abstract: Digester supernatants and/or liquors from sludge dewatering are reacted with an excess of an alkaline reagent having a stronger cation than the ammonium ion and the reaction product is separated into a solution containing aqueous ammonia and solids. The aqueous ammonia derived from the separation stage is heated by free steam under a lowered pressure to free ammonia in gaseous form. The ammonia as a gas, or adsorbed in water, or adsorbed in an acid, or as an acid salt is then mixed with conventionally dried sludge to increase the nitrogen content of the sludge from approximately 1-2 percent to as high as 10 percent.
TL;DR: It is suggested that urea decomposition associated with photosynthetic activity of phytoplankton is one of the major processes of u Andrea decomposition, and that it plays a significant role in the nitrogen supply for phy Topolankton in coastal waters.
Abstract: Decomposition of urea in seawater was studied in Mikawa Bay, a shallow eutrophic bay on the southern coast of central Japan. The urea concentration in seawater ranged from 1.3 to 5.9 μg-at. N/1 and comprised 12 to 40% of the dissolved organic nitrogen. Using 14C labelled urea, the rate of CO2 liberation from urea and the incorporation rate of urea carbon into the particulate organic matter were determined. For the surface samples, high rates of CO2 liberation from urea as well as the incorporation of urea carbon into the particulate organic matter were observed in the light, while much lower rates were obtained in the dark. Incubation experiments with exposure to different light intensities revealed that the rate of CO2 liberation from urea and the incorporation of urea carbon into particulate organic matter changed with light intensity, showing a pattern similar to that of photosynthesis. The highest liberation and incorporation rates were observed at 12,000 lux. Incubation in light and in dark produced marked decreases and increases, respectively, in urea and ammonia, while no appreciable changes were observed for nitrate and nitrite. It is suggested that urea decomposition associated with photosynthetic activity of phytoplankton is one of the major processes of urea decomposition, and that it plays a significant role in the nitrogen supply for phytoplankton in coastal waters.
TL;DR: Quantitative study of taurine uptake into the pigment epithelium showed that, after 45 min incubation with 0.3-4.5p~-[~H]taurine, tissue/medium ratios of at least 20: 1 were generated, implying that the pigment tissue/ medium ratios are similar to those observed for whole retina under comparable conditions, and imply that this region has a high-affinity-uptake mechanism for taurines.
Abstract: (the concentration used for radioautography), the uptake was mainly into the inner retina. However, as the exogenous taurine concentration was decreased to > 1 p~ the percentage of label accumulated by the photoreceptor layer increased with respect to the total uptake (Table 1). Further studies were carried out with the use of lOmin incubations and exposing the retinas to exogenous taurine concentrations varying from 0.05 to 200pM. The data yielded two apparent K,,, values for the uptake processes of 20-5Op~ for both regions of the retina. A low-affinity K,,, was not observed under these conditions. Pigment epithelium was included in the present radioautographic study and it was heavily labelled, implying that this region has a particularly active mechanism for accumulating taurine. Quantitative study of taurine uptake into the pigment epithelium showed that, after 45 min incubation with 0.3-4.5p~-[~H]taurine, tissue/medium ratios of at least 20: 1 were generated. These values are similar to those observed for whole retina under comparable conditions, and imply that the pigment epithelium also has a high-affinity-uptake mechanism for taurine. It is possible, therefore, that in vivo a major portion of the taurine present in the retina is taken up by the pigment epithelium from the blood stream and is then transferred to the photoreceptor cells. Preliminary evidence to support this has been reported by Young (1969).
Patent•
07 Feb 1975
TL;DR: In this paper, aldehydes or ketones are selectively oxidized by hydrogen peroxide to the corresponding azines when they are reacted in the presence of both an amide of a carboxylic acid having a pK greater than about 4.3 and a co-catalyst having the general formula H--X--Y=Z, wherein H is hydrogen, X and Z are each atom of oxygen or nitrogen and Y is an atom of carbon, nitrogen, arsenic, antimony, phosphorus, sulfur, selenium or tellurium; the atoms
Abstract: Ammonia and aldehydes or ketones are selectively oxidized by hydrogen peroxide to the corresponding azines when they are reacted in the presence of both (a) an amide of a carboxylic acid having a pK greater than about 4.3 and (b) a co-catalyst having the general formula H--X--Y=Z, wherein H is hydrogen, X and Z are each an atom of oxygen or nitrogen and Y is an atom of carbon, nitrogen, arsenic, antimony, phosphorus, sulfur, selenium or tellurium; the atoms of X, Y, and Z carrying other substituents necessary to obey the rules of valence. Preferred co-catalysts include di(alkali metal) hydrogen phosphates, lower dialkyl phosphate esters, bicarbonates and p-toluene sulfonic acid. When 1° or 2° amines are also present, hydrazones are also formed along with the azines. Uses of the resultant products include their hydrolysis to hydrazines with recycling of aldehyde or ketone.
TL;DR: In this paper, the enthalpy of dissociation of aqueous ammonium ion, ΔHo(NH4+), can be represented in this temperature range by ΔH o (NH 4 + )/kJ mol −1 = 48.49 + 0.0114 T K.
Patent•
22 Jul 1975
TL;DR: In this paper, high active, hydrothermally stable and ammonia-stable Y zeolite compositions are disclosed, which compositions are useful as adsorbents, hydrocarbon conversion catalysts, and as acidic supports for catalytic metals.
Abstract: Highly active, hydrothermally stable and ammonia-stable Y zeolite compositions are disclosed, which compositions are useful as adsorbents, hydrocarbon conversion catalysts, and as acidic supports for catalytic metals. The stabilized Y zeolite composition is prepared from a sodium Y zeolite by a novel sequence of: (1) partial exchange of ammonium ions for sodium ions, (2) steam calcination under controlled conditions of time, temperature and steam partial pressure, and (3) further ion exchange of ammonium ions for sodium ions to reduce the final Na 2 O content to below about one weight-percent.
Patent•
12 Nov 1975TL;DR: In this paper, an analytical catalyst capable of forming nitrogen and water from ammonia and nitrogen oxides was used to determine the concentrations of nitrogen oxide before and after contact with the analytical catalyst.
Abstract: An ammonia gas to be determined, and an oxidative gas containing nitrogen oxides in moles more than those of the ammonia are brought into contact with an analytical catalyst capable of forming nitrogen and water from ammonia and nitrogen oxides. Concentrations of nitrogen oxides of the gas before and after the contact with the analytical catalyst are determined, and an ammonia concentration of the gas is determined by converting the difference between the concentrations of nitrogen oxides to the ammonia concentration by calculation.
Patent•
17 Jun 1975
TL;DR: A completely one-step permanent wave solution which is harmless and effective on hair to provide odorless, nonporous and silky and intrinsic permanent wave hair and consisting of ammonium thioglycolate, oxy-organic acid, ethyl alcohol, caustic alkali, ammonia water, organic amines and water as mentioned in this paper.
Abstract: A completely one-step permanent wave solution which is harmless and effective on hair to provide odorless, non-porous and silky and intrinsic permanent wave hair and consisting of ammonium thioglycolate, oxy-organic acid, ethyl alcohol, caustic alkali, ammonia water, organic amines and water. The solution is applied to the hair and does not require an oxidizing treatment.
TL;DR: It is pointed out that synthesis of urea from COZ and NH: is a process which, in the normal liver, utilizes NADPH at a comparable rate, and reductive amination of 2-oxoglutarate to glutamate may be considered to be 3ne of the major NADPH requiring reactions of the liver cell.
Patent•
03 Jul 1975
TL;DR: In this article, a process for the production of ethylene glycol, alkali metal salts of glycine and glycolic acid by the hydrogenation of oxalic acid or an alkaline metal hydrogen oxalate, optionally in the presence of ammonia, was described.
Abstract: A process for the production of ethylene glycol, alkali metal salts of glycine, alkali metal salts of glycolic acid, alkali metal salts of diglycolic acid and alkali metal salts of nitrilotriacetic acid by the hydrogenation of oxalic acid or an alkali metal hydrogen oxalate, optionally in the presence of ammonia, said oxalic acid or alkali metal hydrogen oxalate containing less than two moles water of hydration.
TL;DR: It was concluded that the disappearance of nitrogen that occurred between the cecum and colon was in the form of ammonia, and that the value of urea as a nitrogen source resulted primarily from tissue synthesis of dispensable amino acids and coprophagy.
Abstract: Nitrogen balance and weight changes were determined in two groups of rabbits fed diets containing all natural protein or part nonprotein nitrogen from urea. The rabbits were fed the experimental diets for a 10-week period starting at 7 weeks of age. No significant differences in weight gains or nitrogen retention were found between groups. Total nitrogen, ammonia, urea, and free amino acid levels were determined in the contents of several segments of the gastrointestinal tract of the rabbits fed both diets. Significantly less total nitrogen, ammonia, and free amino acids were found in the lower colon compared with the cecal contents of both groups. Subsequent studies with (C)alanine revealed considerable fermentation of alanine in both the cecum and upper colon contents, but there was little absorption into the blood. It was concluded that the disappearance of nitrogen that occurred between the cecum and colon was in the form of ammonia, and that the value of urea as a nitrogen source resulted primarily from tissue synthesis of dispensable amino acids and coprophagy.
TL;DR: In this paper, the differential heat of adsorption of ammonia on synthetic zeolites was measured and the distribution of the surface acidity was discussed in relation to the catalytic activity for cumene-cracking as a function of zeolite compositions.
Abstract: The differential heat of adsorption of ammonia on synthetic zeolites was calorimetrically measured and the distribution of the surface acidity was discussed in relation to the catalytic activity for cumene-cracking as a function of zeolite compositions. A newly designed apparatus, a twin-conduction-type calorimeter equipped with a semiconductor thermoelement and an adsorption apparatus, was used for the direct measurement of the differential heat of adsorption. The differential heat of adsorption of ammonia decreased with the increase in surface coverage, the acid site on the surface becoming stronger up to 27 kcal/mol for ammonia-adsorption when the ratio of silica to alumina was higher and the content of exchanged ammonium ions was higher. The cumene-cracking reaction was effectively catalyzed by zeolites having such sites with heat of adsorption of ammonia exceeding 25 kcal/mol.