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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 supercritical water oxidation (SCWO) system for high concentrations of phenol and 2,4-dinitrophenol (DNP) was investigated in a pilot-scale SCWO system.
Abstract: The oxidation of high concentrations of phenol and 2,4-dinitrophenol (DNP) was investigated in a pilot-scale supercritical water oxidation (SCWO) system. Treatment for approximately 40 s at a pressure of 25 MPa, temperatures of 666–778 K and oxygen excess of 0–34%, resulted in phenol destruction from 94 to 99.98%, consistent with extrapolations of some global rate laws proposed in the literature. Destruction of total organic carbon (TOC) varied from 75 to 99.77%. Two different solutions that contained DNP were studied following the phenol experiments. The first solution contains 2.4 wt.% of 2,4-DNP with 2.1 wt.% of ammonium sulphate. Treatment at under 43 s at 25 MPa, 780 K with a large oxygen excess, resulted in destruction efficiencies of over 99.9996% for DNP and 99.92% for TOC. Mono-nitrophenols were detected as intermediates, but not in the final effluent, where residuals of ammonium bicarbonate and sulphates were detected. This solution was extremely corrosive to the Alloy 625 preheaters at temperatures of approximately 370 °C. The second solution contained 2.26 wt.% of 2,4-DNP, with ammonia but no sulphates and was treated at 24.5 MPa, 742–813 K and oxygen concentrations ranging from sub-stoichiometric to 67% excess. Destruction efficiencies for 2,4-dinitrophenol were over 99.9996% in all cases. TOC destruction efficiencies ranged from 98.98 to 99.98%, while ammonia destruction ranged from 15 to 50%. Picric acid and mono-nitrophenols were detected as intermediates, but not in the liquid effluent. No CO or NOx was present in the effluent gas samples, except in cases with less than stoichiometric oxygen.

73 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis of ammonia using NTP and a Ru-based, multifunctional catalytic system deposited on mesoporous Si-MCM-41 was reported.

73 citations

Journal ArticleDOI
TL;DR: It has been found that Pd-Cu combined catalysts prepared at a mass ratio of 4:1 can maximize the nitrate reduction into nitrogen gas.

73 citations

Journal ArticleDOI
TL;DR: In this article, the uptake of gas-phase ammonia by sulfuric acid surfaces was measured as a function of temperature (248−288 K), gas−liquid interaction time (2−15 ms), and acid concentration (20−70 wt % H2SO4) using a droplet train apparatus.
Abstract: The uptake of gas-phase ammonia by sulfuric acid surfaces was measured as a function of temperature (248−288 K), gas−liquid interaction time (2−15 ms), and acid concentration (20−70 wt % H2SO4) using a droplet train apparatus. The uptake coefficient increases as a function of acid concentration and reaches unity at about 55 wt % H2SO4. The increased NH3 uptake in acid solution is apparently due to reaction between NH3 and H+ at the gas−liquid interface. The results yielded parameters required to model the reaction of NH3 with H+ at the gas−liquid interface. These uptake experiments were expanded to include a detailed study of gas transport to a moving train of droplets. An analysis of previous sulfuric acid aerosol neutralization experiments shows that the uptake of ammonia by ternary NH3−H2SO4−H2O solutions is significantly lower than that by fresh binary H2SO4−H2O solutions. At typical tropospheric water and ammonia vapor concentrations, NH3 uptake coefficients need to be included in detailed microphysi...

73 citations

Journal ArticleDOI
TL;DR: The use of boric acid for trapping ammonia in the micro-Kjeldahl determination is examined in this paper, where a suitable procedure, together with a modified type of micro-distillation apparatus, is described.
Abstract: The use of boric acid for trapping ammonia in the micro-Kjeldahl determination is examined. A suitable procedure, together with a modified type of micro-distillation apparatus, is described. The buffer capacity of boric acid solutions was examined in relation to the sensitivity in the titration of ammonia dissolved in them. Two grades of boric acid, ‘pure’ (technical) and AnalaR, were compared; the former showed appreciable buffering on the acid side. The pH values of solutions of both grades decreased with increasing concentration. The sensitivity of the three indicators examined for the titration of ammonia diminished with increasing concentration of boric acid as a result of the increased buffering. With concentrated boric acid, all three indicators showed wide transitional periods at the end-point, but in solutions of concentration up to 1-0% of AnalaR grade the end-points shown by all three indicators were sharp. The methylene blue-methyl red indicator, however, was generally preferable. The ammonia-fixing capacity of boric acid was studied in air-bubbling tests and by recovery of a known amount of ammonia by distillation. A volume of 10 ml. of 1-0% boric acid fixed 5 mg. of nitrogen as ammonia sufficiently firmly to afford accurate analyses. For macro-determinations, 100 ml. of 2-0% boric acid held firmly up to 90 mg. of nitrogen.

73 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