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Showing papers on "Ammonia published in 1978"


Journal ArticleDOI
TL;DR: The reduction rate data suggest that the pathway of nitrate reduction to ammonia is important in coastal sediments.
Abstract: Simultaneous determinations of nitrogen gas production, ammonia, and particulate organic nitrogen formation in the coastal sediments of Mangoku-Ura, Simoda Bay, and Tokyo Bay were made by using the 15N-label tracer method. The rate of nitrogen gas production in the sediment surface layer was about 10−2 μg atom of N per g per h, irrespective of the location of the sediments examined. [15N]ammonia and -particulate organic nitrogen accounted for 20 to 70% of the three products, and after several hours of incubation, the major fraction of nondenitrified 15N in Mangoku-Ura and Simoda Bay sediments was recovered as ammonia. In Tokyo Bay sediments, particulate organic nitrogen was produced at a greater rate than was ammonia. The reduction rate data suggest that the pathway of nitrate reduction to ammonia is important in coastal sediments.

235 citations



Journal ArticleDOI
TL;DR: The adsorption of ammonia, hydrogen, and nitrogen on a Ru(0001) surface has been investigated by Auger electron spectroscopy, low-energy electron diffraction, and thermal flash desorption as mentioned in this paper.

139 citations


Journal ArticleDOI
TL;DR: This paper showed that ozone-initiated oxidation of ammonia in water can result from the direct reaction of ozone with ammonia as well as from the reactions of hydroxyl radicals formed upon ozone decomposition.
Abstract: A laboratory study showed that ozone-initiated oxidation of ammonia in water can result from the direct reaction of ozone with ammonia as well as from the reactions of hydroxyl radicals formed upon ozone decomposition. The direct reaction of ozone predominated at pH 9, the hydroxyl ion and radical-catalyzed decomposition of ozone to the reactive hydroxyl radical intermediate determines the kinetics of the ammonia oxidation. The reaction rate constant of hydroxyl radical with ammonia is relatively small. Whenever the hydroxyl radical mechanism is involved, ammonia is easily protected by other solutes which also consume hydroxyl radicals. Even carbonate and bicarbonate ions may act as efficient hydroxyl radical scavengers. Because carbonate and organic solutes affect the lifetime of ozone in water, they consequently shift the pH range in which either the direct ozone or the hydroxyl radical mechanism predominates.

135 citations


Journal ArticleDOI
TL;DR: In this article, an in vitro fecal incubation system was used to demonstrate how lactulose influences ammonia metabolism in the colon, and the effect of low pH in reducing generation of ammonia appears to be part of a general reduction in bacterial metabolism.

126 citations


Journal ArticleDOI
Folke Nydahl1
TL;DR: In this paper, a new reagent is proposed whose concentrations of peroxodisulphate and sodium hydroxide are founded on the stoichiometric relations at the autodecomposition of the peroxidisulate; the proper pH of 8.0 for the reduction is achieved by addition of the calculated amount of Tris(hydroximethyl)aminomethane hydrochloride.

124 citations


Journal ArticleDOI
TL;DR: In this paper, a study of the electrooxidation of ammonia as a possible new method of ammonia removal during waste-water treatment was undertaken. But the most favorable potentials were determined using a conventional three electrode electrolytic cell.
Abstract: A study was undertaken of the electro-oxidation of ammonia as a possible new method of ammonia removal during waste-water treatment. Reaction rates were measured in the concentration range of 1.2×10−4 M to 1×10−2 M ammonia and at pH values of 5–13. The influence of the polarization rate (0.05–0.5 V min−1) and the ammonia concentrations on the oxidation peak current were studied. A number of electrocatalysts were evaluated and most favourable potentials were determined using a conventional three electrode electrolytic cell.

106 citations


Journal ArticleDOI
TL;DR: In this article, the intact nodules attached to the upper part of soybean roots were exposed to 15N2 and the incorporation of 15N into various soluble nitrogen constituents was investigated.
Abstract: The intact nodules attached to the upper part of soybean roots were exposed to 15N2 and the incorporation of 15N into various soluble nitrogen constituents was investigated. Results indicated that ammonia, a primary product of N2 fixation, was located in more than two compartments. Ammonia reduced from N2 gas seemed to be incorporated firstly into glutamine especially amido-group nitrogen. Newly fixed nitrogen was secondly incorporated into glutamic acid and alanine in this sequence. These results suggested that fixed ammonia was assimilated by glutamine synthetase/glutamate synthase pathway. Turn-over rate of allantoin plus allantoic acid and serine was relatively high, although apparently these compounds were not primary products of newly fixed ammonia. 15N content of allantoin was always higher than that of allantoic acid. 15N incorporation to aspartic acid and asparagine was relatively slow, especially in early period. In bacteroid fraction there is much amount of ammonia comparing with other...

83 citations


Journal ArticleDOI
TL;DR: In this article, the reactions of oxygen with ammonia have been studied over the Pt(S) -12(111) × (111) surface for pressures between 10−10 and 10−8 Torr over the temperature range −75 to 600 °C.

72 citations


Patent
Tsoung-Yuan Yan1
20 Apr 1978
TL;DR: In this article, a method of treating a subterranean formation which has undergone an in situ leaching operation which utilised an ammonium solution as the lixiviant is presented.
Abstract: A method of treating a subterranean formation which has undergone an in situ leaching operation which utilzed an ammonium solution as the lixiviant. In such a leach operation, ammonium ions will exchange into the clay in the formation and will present a threat of contamination to any ground waters that may be present in the formation. The present method involves flushing the formation with a halogenated restoration fluid, e.g., chlorinated water having a halogen therein which reacts with ammonia within the formation to decompose the ammonia to nitrogen. The halogenated restoration fluid can be continuously injected or it can be injected as a slug followed by a relatively halogen-free solution to complete the operation. The ammonia concentration of the produced fluids is monitored and when it drops below a desired value, the method is complete.

70 citations


Journal ArticleDOI
TL;DR: In this paper, the chemical composition of Pasadena rainwater was compared with the composition of sea salt, soil dust, fuel oil, flyash, automobile aerosol, cement dust, and gaseous air pollutants.
Abstract: Research report:Wet-precipitation-only samplers were used to collect acid rainfall in Pasadena, Calif., from February 1976-September 1977. The concentrations of the cations (hydrogen+, ammonium+, potassium+, calcium2+, and magnesium2+) and the anions (chlorine-, nitrate-, and sulfate-) were measured. The chemical composition of Pasadena rainwater was compared with the composition of sea salt, soil dust, fuel oil, flyash, automobile aerosol, cement dust, and gaseous air pollutants. The results showed 35% of the total residue to be due to nitrate from nitrogen oxides, 20% due to sulfate from sulfur dioxide, 4.4% due to ammonium from ammonia, 17.2% due to soil dust, 13.6% due to sea salt aerosol, less than 7% due to fuel oil fly ash, 1.5% due to automobile aerosol, and less than 2% due to cement dust. The most important of these pollutants in Pasadena rainwater are HN03 and NH4. HNO3 is the dominant air pollutant acid in Pasadena, in contrast with the eastern U.S., where HNO3, although increasing in importance, is still less significant than sulfuric acid. (1 graph, 16 references, 2 tables)

Journal ArticleDOI
TL;DR: The experiments support the view that hepatic glutamate dehydrogenase can supply the required ammonia in urea synthesis for the carbamoyl phosphate synthase reaction (EC 2.7.2.5).
Abstract: The initial rate of incorporation of [15N]alanine into the 6-amino group of the adenine nucleotides in rat hepatocytes was about one-eighteenth of the rate of incorporation into urea Thus the purine nucleotide cycle cannot provide most of the ammonia needed in urea synthesis for the carbamoyl phosphate synthase reaction (EC 2725) On the other hand, contrary to the view expressed by McGivan & Chappell [(1975) FEBS Lett 52, 1–7], the experiments support the view that hepatic glutamate dehydrogenase can supply the required ammonia


Journal ArticleDOI
TL;DR: All three of the major human nitrogenous waste products--urea, creatinine, and uric acid--are significantly degraded by intestinal bacteria, and metabolites of these complex heterocyclic nitrogen compounds may well turn out to play a role in uremic toxicity.

Journal ArticleDOI
TL;DR: In this paper, the authors used urease immobilized in an enzyme reactor to determine the amount of mercury in the mixture of urea and bicarbonate and ammonia, the latter being measured by an ammonia gas electrode.

Journal ArticleDOI
TL;DR: In this paper, it was shown that direct nitrogen isotope measurements of atmospheric ammonia at Julich are in the expected range calculated from the δ ranges of different sources, which is explained by isotope fractionations during rainout and washout.
Abstract: Preliminary nitrogen isotope data for ammonia from animal urine, fuel combustion, fertilizer use and fertilizer factories have been measured or estimated. It turns out that direct nitrogen isotope measurements of atmospheric ammonia at Julich are in the expected range calculated from the δ ranges of different sources. For deposition of atmospheric ammonium in Julich-rain a depletion in15N with respect to atmospheric ammonia has been found which is explained by isotope fractionations during rainout and washout. In correspondence with this fractionation model are nitrogen isotope data of rain-ammonium from coastal areas, which are enriched in15N due to the fact that sea water acts as a sink for atmospheric ammonia. For Julich rain-nitrate a pronounced seasonal trend has been detected with lower15N data in spring and summer than in autumn and winter. This trend is interpreted by different nitrogen isotope data of anthropogenic and natural nitric oxides which have been measured or estimated from isotope fractionation effects during nitrification and denitrification reactions in soils. It should be possible to get better global estimations for anthropogenic and natural nitric oxides from nitrogen isotope measurements.

Journal ArticleDOI
TL;DR: A technique for optimising reagent concentrations on the AutoAnalyzer has been applied to the estimation of ammonia by the Berthelot reaction in the determination of urea and organic nitrogen and revealed that the optimum concentration of phenol and salicylate is about four times that of the former.
Abstract: A technique for optimising reagent concentrations on the AutoAnalyzer has been applied to the estimation of ammonia by the Berthelot reaction in the determination of urea and organic nitrogen. Comparison of the use of phenol and salicylate revealed that the optimum concentration of the latter is about four times that of the former. The optimum concentration of hypochlorite is five times greater with salicylate than with phenol, and for the catalyst, sodium nitroprusside, the factor is two. The precision obtained with the different methods is similar.

Journal ArticleDOI
TL;DR: In this article, the uptake rates for ammonia and nitrate were measured in limnocorrals and in the adjacent water in the Bay of Quinte, Ontario, where they were integrated with sedimentation, N release by zooplankton excretion and N2-fixation.
Abstract: The uptake rates for ammonia and nitrate were measured in limnocorrals and in the adjacent water in the Bay of Quinte, Ontario. Even though the net change of nitrate exceeds that for ammonia over the summer, it is ammonia that is the most significant source of N for the plankton. The uptake rates were light dependent; in the dark uptake of nitrate was reduced 60–95% and ammonia by 40–70%. The uptake of N is not correlated to net production but to gross production. These rates were integrated with sedimentation, N release by zooplankton excretion, and N2-fixation. Although N2-fixation provides only a small amount of the daily N requirement compared with ammonia uptake, ammonia is rapidly recycled and the N2-fixation is the vital process controlling the amount of this essential nutrient in systems where it is in short supply (corral II). Zooplankton grazing and sedimentation (decomposition) can account for much of the ammonia regeneration, but direct release of ammonia from the plankton appeared to be impor...

Journal ArticleDOI
TL;DR: In this article, the rate of the NO-NH 3 reaction showed dependence on the partial pressures of both No and NH 3, in accordance with the Langmuir-Hinshelwood type of rate equation.

Journal ArticleDOI
TL;DR: Nickel extraction from ammoniacal media, containing, initially, 0.03 mol dm−3 of nickel, by 10% v/v Shell metal extractant 529 in MSB 210 or Shellsol A, has been studied as a function of pH, counter anions (nitrate or sulphate), ammonium salt concentration, temperature (10 to 50°C), and the presence of copper, cobalt and zinc.

Journal ArticleDOI
TL;DR: Conidia of Aspergillus nidulans germinated on glutamate have a single system for the active transport of ammonia and methylamine against a concentration gradient and it is proposed that the system functions in the scavenging of low concentrations of ammonia during nitrogen starvation or during growth on other major nitrogen sources.
Abstract: Summary: Conidia of Aspergillus nidulans germinated on glutamate have a single system for the active transport of ammonia and methylamine against a concentration gradient. The transport of methylamine is inhibited by azide, N-ethylmaleimide, valinomycin and anaerobiosis; it has a pH optimum of about 6·3 and a temperature optimum of 40°C. The affinity of the system for methylamine (Km 13 μm) is about 20% of that for ammonia; the Vmax is also much lower. This transport system is present in methylamine-resistant mutants (meaA and meaB loci) and its formation is repressed in wild type and mutants by ammonia or a metabolite of ammonia. It is proposed that the system functions in the scavenging of low concentrations of ammonia during nitrogen starvation or during growth on other major nitrogen sources.

Journal ArticleDOI
TL;DR: In this paper, a twin conduction type microcalorimeter was used to measure the initial heat of adsorption of ammonia on several solid acids, including silica-alumina and zeolite.
Abstract: The differential heats of adsorption of ammonia on several solid acids were measured by means of a twin conduction type microcalorimeter, and surface acid strength distribution and acidity were evaluated. Silica–alumina showed very high initial heats which were not observed in decationated zeolite and silica–magnesia. The acidity of zeolite was about 6 times as high as that of silica–alumina, showing very charactristic acid site distribution at 100 kJ/mol of adsorption energy, and suggesting the existence of homogeneous acid sites. The surface water modified surface acidic nature transforming strong acid sites into weaker ones. The poisoning of acid sites of silica-alumina with alkali occurred preferentially at sites on which adsorption energy of ammonia was 96–105kJ/mol.

Patent
Perry Eli1
20 Mar 1978
TL;DR: In this paper, a purge stream from an ammonia synthesis loop is treated to reduce its ammmonia content to less than about 0.5 volume percent, and the purge stream is then contacted at a pressure of at least substantially the superatmospheric synthesis pressure of the ammonia synthesis with the feed side of a separation membrane which exhibits selective permeation of hydrogen as compared to the permeations of each of methane and argon.
Abstract: Ammonia synthesis processes are disclosed which provide enhanced conversion of hydrogen values to ammonia. In the processes, a purge stream from an ammonia synthesis loop is treated to reduce its ammmonia content to less than about 0.5 volume percent. The purge stream is then contacted at a pressure of at least substantially the superatmospheric synthesis pressure of the ammonia synthesis with the feed side of a separation membrane which exhibits selective permeation of hydrogen as compared to the permeation of each of methane and argon. A total pressure differential is maintained across the membrane to provide a driving force for hydrogen permeation through the membrane. A hydrogen-rich permeating gas is obtained on the permeate exit side of the membrane. The permeating gas is combined with gas passing to the ammonia synthesis reaction zone for conversion to ammonia. For instance, the permeating gas can be combined with synthesis feed gas or directly introduced into the ammonia synthesis loop. A non-permeating gas is removed from the feed side of the separation membrane at substantially the same pressure at which the purge stream is contacted with the separation membrane and provides a valuable source of energy due to its high pressure and combustible gas content.

Patent
27 Mar 1978
TL;DR: In this paper, a liquid medium containing glucose or sucrose as main carbon source was used to culture L-glutamic acid-producing bacteria under specific conditions, and aqueous ammonic (or ammonia gas) or an alkali hydroxide was added to the medium to keep the ammonium ion concentration in the medium between 0.3 and 10 g/d1.
Abstract: PURPOSE:To increase the concentration of glucose or sucrose in the culturing medium to more than 1.5 times the one obtainable by the conventional process, and to increase the amount of L-glutamic acid accumulated in the medium, by culturing L-glutamic acid-producing bacteria under specific conditions. CONSTITUTION:L-glutamic acid-producing bacteria (e.g. Brevibacterium devaricatum, Corynebacterium acetoacidiphilum) are inoculated in a liquid medium containing glucose or sucrose as main carbon source, and aerobically cultured. When the concentraion of the sucrose is decreased to a predetermined value below 10 g/1, glucose or sucrose is added to the medium, and at the same time, aqueous ammonic (or ammonia gas) or an alkali hydroxide is added to the medium to keep the ammonium ion concentration in the medium between 0.3 and 10 g/d1. The aqueous ammonia raises the concentration, while the alkali hydroxide lowers.

Journal ArticleDOI
TL;DR: In this paper, experimental measurements have confirmed the accuracy of earlier calculations of the extent of hydrolysis of ammonium ions in sea water over a range of temperature and salinity.
Abstract: Recent experimental measurements have confirmed the accuracy of earlier calculations of the extent of hydrolysis of ammonium ions in sea water over a range of temperature and salinity. Tables of the percentage of un-ionized ammonia in sea water compiled from the calculated data can therefore be used with confidence in assessing ammonia toxicity in mariculture systems.

Patent
Harold R Null1, Eli Perry1
20 Mar 1978
TL;DR: In this article, a purge stream from an ammonia synthesis loop, which purge stream contains ammonia, is contacted at a superatmospheric pressure with the feed side of a separation membrane which exhibits selective permeation of each of hydrogen and ammonia.
Abstract: Ammonia synthesis processes are disclosed which provide enhanced conversion of hydrogen values to ammonia. In the processes, a purge stream from an ammonia synthesis loop, which purge stream contains ammonia, is contacted at a superatmospheric pressure with the feed side of a separation membrane which exhibits selective permeation of each of hydrogen and ammonia as compared to the permeation of each of methane and argon. A total pressure differential across the membrane is maintained to provide a driving force for the permeation of hydrogen and ammonia through the membrane. A hydrogen-rich permeating gas which contains ammonia is obtained on the permeate exit side of the membrane. The permeating gas is combined with the gas in the ammonia synthesis loop and passed to the ammonia synthesis reaction zone for conversion to ammonia. Ammonia which permeates the membrane can be recovered by the means to remove product ammonia from the gas in the synthesis loop. A non-permeating gas is removed from the feed side of the separation membrane at substantially the same pressure at which the purge stream is contacted with the separation membrane.

Patent
19 Apr 1978
TL;DR: In this article, ammonium acid fluoride along with elemental fluorine is injected into ammonium trifluoride to maintain a molar ratio of by-product hydrogen fluoride to ammonia of approximately 2.0 to 2.5.
Abstract: Nitrogen trifluoride is prepared by passing elemental fluorine in intimate contact with liquid phase ammonium acid fluoride maintained at a temperature above its melting point but below about 400° F for a time sufficient to effect reaction. Generally, ammonia is injected into the ammonium acid fluoride along with the fluorine to maintain a molar ratio of by-product hydrogen fluoride to ammonia of approximately 2.0 to 2.5.

Journal ArticleDOI
TL;DR: In this paper, the reduction of nitric oxide by ammonia has been studied over a stepped platinum single crystal surface in a vacuum system equipped with Auger electron spectroscopy, low-energy electron diffraction, and mass spectrometry.

Journal ArticleDOI
TL;DR: In this article, the decomposition of ammonium uranate powders in hydrogen was studied to determine those properties of AU which affect decomposition reactions and influence the properties of the final UO2 powder.

Journal ArticleDOI
TL;DR: An automated system for the analysis of dissolved organic nitrogen has been developed and applied to natural waters as discussed by the authors, which is based on subjecting sample to u.v. irradiation followed by a heterogeneous reduction of the nitrogen containing irradiation products to ammonia which is detected by an ammonia gas sensing probe.