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Ammonia

About: Ammonia is a research topic. Over the lifetime, 16217 publications have been published within this topic receiving 271940 citations. The topic is also known as: NH3 & azane.


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Journal ArticleDOI
TL;DR: In this paper, a secondary aerosol equilibrium model, SEQUILIB, is applied to evaluate the effects of emissions reductions from precursor species on ambient concentrations during the winter in Phoenix, Arizona.
Abstract: A secondary aerosol equilibrium model, SEQUILIB, is applied to evaluate the effects of emissions reductions from precursor species on ambient concentrations during the winter in Phoenix, Arizona. The model partitions total nitrate and total ammonia to gas-phase nitric acid and ammonia and to particle-phase ammonium nitrate. Agreement between these partitions and ambient measures of these species was found to be satisfactory. Equilibrium isopleths were generated for various ammonium nitrate concentrations corresponding to high and low humidity periods which occurred during sampling. These diagrams show that ammonia is so abundant in Phoenix that massive reductions in its ambient concentrations would be needed before significant reductions in particulate ammonium nitrate would be observed. When total nitrate is reduced by reductions in its nitrogen oxides precursor, proportional reductions in particulate nitrate are expected. Many of the complex reactions in SEQUILIB do not apply to Phoenix, and its ability...

107 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated acute inhibitory effects of ammonia on methanogenesis by using pulses of ammonium chloride, and assessed whether volatile fatty acids (VFAs) could be used as process indicators.
Abstract: In continuously stirred tank reactor experiments using pig manure codigested with solid fractions separated from pig manure (a mass mixture ratio of 40:60) with an organic loading rate of 9.4 gVS/ldigester/day at a thermophilic temperature of 51°C, we investigated acute inhibitory effects of ammonia on methanogenesis by using pulses of ammonium chloride, and assessed whether volatile fatty acids (VFAs) could be used as process indicators. Codigestion with the solid fractions seemed to result in a slight ammonia inhibition effect, though the digestion process was stable and the methanogens were adapted to a high ammonia concentration. We found a strong negative correlation (R 2 = 0.91) between total ammonia concentration and methane gas yield. However, free ammonia concentration did not reflect the acute ammonia inhibition significantly. Compared to a control reactor which was at an ammonia concentration of 4.6 gNH4–N/l, without pulsing ammonium chloride, a 50% decrease in methane gas yield in terms of loa...

107 citations

Journal ArticleDOI
TL;DR: Using oxalic acid as a hole scavenger, the photocatalytic reduction of nitrate in aqueous dispersions of TiO 2 has been investigated in this article, where the effects of concentrations of nitrates, of oxalate, and of pH were studied.
Abstract: Using oxalic acid as a hole scavenger, the photocatalytic reduction of nitrate in aqueous dispersions of TiO 2 has been investigated. Oxalic acid accelerates the reaction considerably compared to the reaction in the absence of oxalic acid. In the presence of nitrate, the oxidation of oxalate is also accelerated. The reduction product of the nitrate is mainly ammonia. The effects of concentrations of nitrate, of oxalate, and of pH were studied. The adsorption of the reactants on TiO 2 is an important factor for accelerating the reaction.

107 citations

Journal ArticleDOI
Chong Qiu1, Lin Wang1, Vinita Lal1, Alexei F. Khalizov1, Renyi Zhang1 
TL;DR: The results reveal that the reactions between alkylamines and ammonium salts contribute to particle growth and alter the composition of ammonium sulfate and bisulfate aerosols in the atmosphere.
Abstract: The heterogeneous reactions between alkylamines and ammonium salts (ammonium sulfate and ammonium bisulfate) have been studied using a low-pressure fast flow reactor coupled to an ion drift-chemical ionization mass spectrometer (ID-CIMS) at 293 ± 2 K. The uptake of three alkylamines, i.e., monomethylamine, dimethylamine, and trimethylamine, on ammonium sulfate shows a displacement reaction of ammonium by aminium, evidenced by the release of ammonia monitored using protonated acetone dimer as the reagent ion. For the three alkylamines, the initial uptake coefficients (γ0) range from 2.6 × 10–2 to 3.4 × 10–2 and the steady-state uptake coefficients (γss) range from 6.0 × 10–3 to 2.3 × 10–4 and decrease as the number of methyl groups on the alkylamine increases. A different reaction mechanism is observed for the uptake of the three alkylamines on ammonium bisulfate, which is featured by an acid–base reaction (neutralization) with irreversible alkylamine loss and no ammonia generation and occurs at a rate lim...

107 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of temperature and exhaust gas composition on the cyanuric acid (CA) and the ammonia (NH3) nitric oxide reduction processes and examines the decomposition of dry urea.
Abstract: Selective, non-catalytic techniques for removing nitric oxide (NO) from the exhaust gases of combustion processes include the addition of cyanuric acid, ammonia, or urea to the hot exhaust. This paper compares the effects of temperature and exhaust gas composition on the cyanuric acid (CA) and the ammonia (NH3) nitric oxide reduction processes and examines the decomposition of dry urea. The experiments were conducted in an electrically heated quartz flow reactor using mixtures of N2, 02, H2, H2, O, CO, and NO that simulated exhaust gases from overall lean hydrocarbon combustion processes Comparison of the CA and the NH3 nitric oxide reduction processes shows that the effects of the exhaust O2, H2, O, and CO concentrations on the NO reduction level and the temperature range over which the NO reduction occurs are different for each process. The comparison also shows that the by-products of each process are different for some conditions. These differences indicate that the detailed chemical mechanis...

107 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,701
20223,035
2021425
2020443
2019496
2018511