Showing papers on "Ammonia published in 2012"
TL;DR: Ammonium recovery and simultaneous energy production from urine was proven possible by this novel approach to simultaneously produce energy and recover ammonium.
386 citations
TL;DR: The study of the long-term effects was carried out in lab-scale Sequencing Batch Reactors inoculated with the biofilm biomass and a total restoration of the SAA was observed after the stoichiometric feeding was applied to the SBR.
240 citations
TL;DR: The ammonium nitrate content of the solid residue is below the limit at which stringent EU safety regulations for fertilizers come into effect; nevertheless, the primary energy demand can be reduced to values very close to conventional treatment, if 80% of the water is removed with reverse osmosis and distillation is operated with vapor compression.
233 citations
TL;DR: The authors used in situ observations from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, the Midwest Ammonia Monitoring Project, 11 surface site campaigns as well as Infrared Atmospheric Sounding Interferometer (IASI) satellite measurements with the GEOS-Chem model to investigate inorganic aerosol loading and atmospheric ammonia concentrations over the United States.
Abstract: We use in situ observations from the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network, the Midwest Ammonia Monitoring Project, 11 surface site campaigns as well as Infrared Atmospheric Sounding Interferometer (IASI) satellite measurements with the GEOS-Chem model to investigate inorganic aerosol loading and atmospheric ammonia concentrations over the United States IASI observations suggest that current ammonia emissions are underestimated in California and in the springtime in the Midwest In California this underestimate likely drives the underestimate in nitrate formation in the GEOS-Chem model However in the remaining continental United States we find that the nitrate simulation is biased high (normalized mean bias > = 10) year-round, except in Spring (due to the underestimate in ammonia in this season) None of the uncertainties in precursor emissions, the uptake efficiency of N2O5 on aerosols, OH concentrations, the reaction rate for the formation of nitric acid, or the dry deposition velocity of nitric acid are able to explain this bias We find that reducing nitric acid concentrations to 75% of their simulated values corrects the bias in nitrate (as well as ammonium) in the US However the mechanism for this potential reduction is unclear and may be a combination of errors in chemistry, deposition and sub-grid near-surface gradients This "updated" simulation reproduces PM and ammonia loading and captures the strong seasonal and spatial gradients in gas-particle partitioning across the United States We estimate that nitrogen makes up 15−35% of inorganic fine PM mass over the US, and that this fraction is likely to increase in the coming decade, both with decreases in sulfur emissions and increases in ammonia emissions
233 citations
TL;DR: It was found out that negative effect of low ammonia nitrogen concentration on biomass is caused not only by low buffer capacity but also by insufficiency of nitrogen as nutrient.
Abstract: Ammonia increases buffer capacity of methanogenic medium in mesophilic anaerobic reactor thus increasing the stability of anaerobic digestion process. Optimal ammonia concentration ensures sufficient buffer capacity while not inhibiting the process. It was found out in this paper that this optimum depends on the quality of anaerobic sludge under investigation. The optimal concentrations for methanogens were 2.1, 2.6 and 3.1 g/L of ammonia nitrogen in dependence on inoculum origin. High ammonia nitrogen concentration (4.0 g/L) inhibited methane production, while low ammonia nitrogen concentration (0.5 g/L) caused low methane yield, loss of biomass (as VSS) and loss of the aceticlastic methanogenic activity. It was found out that negative effect of low ammonia nitrogen concentration on biomass is caused not only by low buffer capacity but also by insufficiency of nitrogen as nutrient. It was also found out that anaerobic sludge with higher ammonia nitrogen concentration (4.2 g/L) tolerates even concentration of volatile fatty acids (160 mmol/L) which causes inhibition of the process with low ammonia nitrogen concentration (0.2 g/L).
223 citations
TL;DR: The relationship between the ammonia oxidation rate (AOR) and nitrous oxide production rate (N(2)OR) of an enriched ammonia-oxidising bacteria (AOB) culture was investigated and indicated a clear exponential relationship.
203 citations
TL;DR: Most diseases resulting in hyperammonemia and cerebral edema are preceded by hyperventilation and respiratory alkalosis of unclear origin that may be caused by the intracellular acidosis occurring in these conditions.
Abstract: Free ammonium ions are produced and consumed during cell metabolism. Glutamine synthetase utilizes free ammonium ions to produce glutamine in the cytosol whereas glutaminase and glutamate dehydrogenase generate free ammonium ions in the mitochondria from glutamine and glutamate, respectively. Ammonia and bicarbonate are condensed in the liver mitochondria to yield carbamoylphosphate initiating the urea cycle, the major mechanism of ammonium removal in humans. Healthy kidney produces ammonium which may be released into the systemic circulation or excreted into the urine depending predominantly on acid-base status, so that metabolic acidosis increases urinary ammonium excretion while metabolic alkalosis induces the opposite effect. Brain and skeletal muscle neither remove nor produce ammonium in normal conditions, but they are able to seize ammonium during hyperammonemia, releasing glutamine. Ammonia in gas phase has been detected in exhaled breath and skin, denoting that these organs may participate in nitrogen elimination. Ammonium homeostasis is profoundly altered in liver failure resulting in hyperammonemia due to the deficient ammonium clearance by the diseased liver and to the development of portal collateral circulation that diverts portal blood with high ammonium content to the systemic blood stream. Although blood ammonium concentration is usually elevated in liver disease, a substantial role of ammonium causing hepatic encephalopathy has not been demonstrated in human clinical studies. Hyperammonemia is also produced in urea cycle disorders and other situations leading to either defective ammonium removal or overproduction of ammonium that overcomes liver clearance capacity. Most diseases resulting in hyperammonemia and cerebral edema are preceded by hyperventilation and respiratory alkalosis of unclear origin that may be caused by the intracellular acidosis occurring in these conditions.
199 citations
TL;DR: It is demonstrated that phase can be a key regulator of the reactivity of atmospheric SOM particles and a mechanism of neutralization and co-condensation of acidic gas-phase species, consistent with a highly viscous semisolid upon which adsorption occurs.
Abstract: The interconversion of atmospheric organic particles among solid, semisolid, and liquid phases is of keen current scientific interest, especially for particles of secondary organic material (SOM). Herein, the influence of phase on ammonia uptake and subsequent particle-phase reactions was investigated for aerosol particles of adipic acid and α-pinene ozonolysis SOM. The nitrogen content of the particles was monitored by online mass spectrometry for increasing ammonia exposure. Solid and semisolid adipic acid particles were inert to the ammonia uptake for low RH ( 94%) induced a first-order deliquescence phase transition into aqueous particles. Solid particles exposed to supersaturated (RH > 100%) conditions and cycled back to high RH (> 94%), thereby becoming acidic metastable particles, underwent a gradual second-order transition upon ammonia exposure to form aqueous, partially neutralized particles. For α-pinene SOM, ammonia exposure at low RH increased the particle-phase ammonium content by a small amount. Mass spectrometric observations suggest a mechanism of neutralization and co-condensation of acidic gas-phase species, consistent with a highly viscous semisolid upon which adsorption occurs. At high RH the ammonium content increased greatly, indicative of rapid diffusion and absorption in a liquid environment. The mass spectra indicated the production of organonitrogen compounds, possibly by particle-phase reactive chemistry. The present results demonstrate that phase can be a key regulator of the reactivity of atmospheric SOM particles.
172 citations
TL;DR: Nitrification rate was unaffected by the incubation of soil with inorganic ammonium but was significantly stimulated by the addition of organic N, and ammonia monooxygenase-dependent activity was completely inhibited by 0.01% acetylene in all treatments, indicating ammonia mono oxygenase- dependent activity.
163 citations
TL;DR: It was concluded that ammonia removal through air stripping at the alkaline pH could be a viable option for preventing the failure of anaerobic digestion of the raw piggery wastewater and a high concentration of sodium ion originated from sodium hydroxide for pH adjustment inhibited methane production.
152 citations
TL;DR: The chosen approach offers an appealing technology to remove ammonia directly from media having high concentrations of solids and it can help to improve process efficiency in anaerobic digestion of ammonia rich substrates.
TL;DR: The synthesis of a bis(imidazolidin-2-iminato)phosphinonitrene is reported, which is stable at room temperature in solution and can even be isolated in the solid state, and the bonding between phosphorus and nitrogen is analogous to that observed for metallonitrenes.
Abstract: A variety of transition metal–nitrido complexes (metallonitrenes) have been isolated and studied in the context of modeling intermediates in biological nitrogen fixation by the nitrogenase enzymes and the industrial Haber-Bosch hydrogenation of nitrogen gas into ammonia. In contrast, nonmetallic nitrenes have so far only been spectroscopically observed at low temperatures, despite their intermediacy in a range of organic reactions. Here, we report the synthesis of a bis(imidazolidin-2-iminato)phosphinonitrene, which is stable at room temperature in solution and can even be isolated in the solid state. The bonding between phosphorus and nitrogen is analogous to that observed for metallonitrenes. We also show that this nitrido phosphorus derivative can be used to transfer a nitrogen atom to organic fragments, a difficult task for transition metal–nitrido complexes.
TL;DR: In this paper, the nucleation of particles composed of sulfuric acid, water, and nitrogen base molecules using a continuous flow reactor was studied using an ultrafine condensation particle counter, while the particles formed from these vapors were detected by chemical ionization mass spectrometry.
Abstract: . Nucleation of particles composed of sulfuric acid, water, and nitrogen base molecules was studied using a continuous flow reactor. The particles formed from these vapors were detected with an ultrafine condensation particle counter, while vapors of sulfuric acid and nitrogen bases were detected by chemical ionization mass spectrometry. Variation of particle numbers with sulfuric acid concentration yielded a power dependency on sulfuric acid of 5 ± 1 for relative humidities of 14–68% at 296 K; similar experiments with varying water content yielded power dependencies on H2O of ~7. The critical cluster contains about 5 H2SO4 molecules and a new treatment of the power dependency for H2O suggests about 12 H2O molecules for these conditions. Addition of 2-to-45 pptv of ammonia or methyl amine resulted in up to millions of times more particles than in the absence of these compounds. Particle detection capabilities, sulfuric acid and nitrogen base detection, wall losses, and the extent of particle growth are discussed. Results are compared to previous laboratory nucleation studies and they are also discussed in terms of atmospheric nucleation scenarios.
TL;DR: In this paper, the stability of ammonium in an ammonium sulfate solution under temperature conditions from 20 to 70°C and pH from 2.1 to 12.6 was examined.
TL;DR: In this paper, an improved ammonia combustion mechanism was validated for the flame structure prediction of ammonia, hydrogen, oxygen, argon flames investigated at several low pressures and for various conditions of equivalence ratio and of initial hydrogen content.
Abstract: It is believed that a TiN coating can increase the electrical conductivity, and consequently the performance, of an electrode. In this work, a simple one-step synthesis of nitrogen- and TiN-modified Li4Ti5O12, i.e. solid-state reaction of Li2CO3 and TiO2 anatase in an ammonia-containing atmosphere, is introduced. The reducing ammonia atmosphere could cause the partial reduction of Ti4+ to Ti3+ and the doping of nitrogen into the Li4Ti5O12 lattice, in addition to the formation of the TiN phase. By controlling the ammonia concentration of the atmosphere and using a slight Ti excess in the reactants, Li4Ti5O12, nitrogen-doped Li4Ti5O12, or TiN-coated nitrogen-doped Li4Ti5O12 were obtained. Both the electrical conductivity and the TiN thickness were closely related to the ammonia concentration in the atmosphere. Synthesis under reducing atmosphere also resulted in powders with a different plate shape particulate morphology from that synthesized in air, and such plate-shape powders had an ultrahigh tap density of ∼1.9 g cm−3. Interestingly, the formation of TiN was not beneficial for capacity improvement due to its insulation towards lithium ions, unlike the nitrogen doping. The sample prepared under 3% NH3–N2, which was free of TiN coating, showed the best electrode performance with a capacity of 103 mA h g−1 even at 20 C with only 3% capacity decay after cycling 100 times.
TL;DR: In this article, the reaction mechanism of ammonia decomposition to nitrogen and hydrogen over platinum loaded titanium oxide photocatalyst was investigated through various reaction tests, as well as ESR and FT-IR spectroscopies.
Abstract: The reaction mechanism of ammonia decomposition to nitrogen and hydrogen over platinum loaded titanium oxide photocatalyst was investigated through various reaction tests, as well as ESR and FT-IR spectroscopies. The photoformed hole on the titanium oxide oxidizes NH3 to form amide radical (•NH2) and proton. The amide radicals produce hydrazine (N2H4), and it can be further decomposed to form nitrogen and hydrogen. On the other hand, the photoformed electron migrates to platinum nanoparticles through the conduction band of the titanium oxide and reduces the proton to yield hydrogen. The metals with larger work function, such as platinum, can provide more effective cocatalysts. In this photocatalytic reaction system, water molecules were essential for the continuous reaction progress. An in situ FT-IR study clarified that water restricted the accumulation of inactive byproduct, ammonium ion (NH4+), on the titanium oxide surface.
TL;DR: The results demonstrate that polyacrylamide (PAM) has an insignificant effect on emission characteristics of nitrogen- and sulfur-containing odorous compounds, because the properties, sulfur and nitrogen speciations are similar in PAM-conditioned sludge and raw sludge (RS).
TL;DR: In this paper, the authors investigated the effect of air stripping from synthetically prepared ammonia solution at the high pH in a semi-batch JLR and found that increasing temperature and air flow rate have a very significant effect on the overall volumetric mass transfer coefficients.
TL;DR: It was concluded that a stable NRR in a moving bed biofilm reactor depended on maintaining FA concentrations below 2 mg N L(-1) when the pH was maintained between 7 and 8, and on maintaining anammox activity in the pH range 7-8.
TL;DR: The study on mechanism of ammonia inhibition suggested it might include an inhibition on the acyl-CoA synthetase activity, since a 61% decrease in the enzyme activity was found when 3140 g m −3 of ammonia was added.
Abstract: Culturing oleaginous yeast with organic residues can provide cheap feedstock for biodiesel production, but the high content of nitrogen in some feedstocks (such as food residues) can lead to inhibition to cell growth and lipid synthesis, and this may be caused by ammonia. Thus, the inhibitory effect of ammonia on the growth of yeast Cryptococcus curvatus and its possible mechanism were evaluated in this study. The biomass production, lipid contents, affected metabolic pathways, and activities of the related pathway enzymes were investigated. The results showed that the yeast biomass production on acetate decreased from 5.9 kg m −3 to 2.0 kg m −3 when the initial ammonia concentration (in nitrogen equivalent terms) increased from 131 g m −3 to 3140 g m −3 . Ammonia significantly inhibited the yeast growth with volatile fatty acids (VFA) as carbon sources, but not in the culture with pyruvate generating substances (PGS) as carbon sources. However, the fatty acid synthesis was suppressed by ammonia in cultures with either VFA or PGS. The study on mechanism of ammonia inhibition suggested it might include an inhibition on the acyl-CoA synthetase activity, since a 61% decrease in the enzyme activity was found when 3140 g m −3 of ammonia (in nitrogen equivalent terms) was added. This study firstly reported the effect of ammonia with high concentrations to oleaginous yeast growth and lipid accumulation, and provided preliminary evidences on its possible mechanism of acyl-CoA synthetase inhibition.
TL;DR: In this article, various nickel catalysts supported on metal oxides were prepared and their catalytic activity for ammonia decomposition was investigated, and the results showed that Ni/Al 2 O 3 catalyst achieved the highest ammonia conversion among catalysts investigated due to the high surface area of Al 2 O3 support (200m 2 ǫg −1 ).
Abstract: Ammonia decomposition is a promising process for on-site generation of hydrogen. In this study, various nickel catalysts supported on metal oxides were prepared and their catalytic activity for ammonia decomposition was investigated. Ni/Al 2 O 3 catalyst achieved the highest ammonia conversion among catalysts investigated due to the high surface area of Al 2 O 3 support (200 m 2 g −1 ). Despite the low surface area of support material (4.7 m 2 g −1 ), the catalytic activity of Ni/La 2 O 3 was comparable to that of Ni/Al 2 O 3 . The basicity of support materials was not specifically related with the catalytic activity. For Ni/La 2 O 3 catalyst, the small nickel particles were deposited over La 2 O 3 from LaNiO 3 during the reduction treatment. When the Ni loading amount was changed in the range of 10–70 wt% for Ni/La 2 O 3 catalyst, the sample with 40 wt% Ni exhibited the highest conversion of 78.9% at 550 °C. The catalytic performance of Ni/La 2 O 3 was also affected by the preparation method and calcination temperature. The LaNiO 3 formation was responsible for the high activity of Ni/La 2 O 3 catalyst for the ammonia decomposition.
TL;DR: In this article, the authors describe a novel route to produce magnesium hydroxide, Mg(OH) 2, from Finnish serpentinite, which is much more reactive towards CO 2 than the parent serpentinite.
TL;DR: In this article, the authors extended the FREZCHEM model to include ammonium and ammonium compounds, and explored the role of these chemistries on Enceladus and Titan, mindful of their astrobiological implications.
TL;DR: In this article, the influence of various salinity levels [1 (control), 9 (medium), 17 (high), and 27 dS m−1 (strong)] on nitrogen transformations in soil fertilized with urea and ammonium sulfate was investigated.
Abstract: Laboratory experiments were carried out to study the influence of various salinity levels [1 (control), 9 (medium), 17 (high), and 27 dS m–1(strong)] on nitrogen (N) transformations in soil fertilized with urea and ammonium sulfate. Generally, soil salinization affected the normal pathway of N transformations. The results showed that salinity (medium to high) inhibited the second step of nitrification, causing nitrite (NO2 −) accumulation in soil. The inhibition was more severe in cases of high level of salinity. The greatest salinity level caused inhibition of even the first step of nitrification, leaving more ammonium (NH4)-N accumulation in soil. Severity in nitrification inhibition was observed with increase in salinity and rate of N application, which declined with time. Ammonium accumulation with increased salinity caused N losses in the form of ammonia (NH3) volatilization. After 14 days, the NH3 losses were 1.4-, 2-, and 5-fold greater at 9, 17, and 27 dS m–1 than that of the control (1 dS m–1). A...
TL;DR: Co/γ-Al 2 O 3 catalysts with 4-27-wt% cobalt loadings were prepared by incipient-wetness impregnation and used to catalyze the synthesis of monoisopropylamine by reductive amination of 2-propanol in the presence of hydrogen and ammonia.
Abstract: Co/γ-Al 2 O 3 catalysts with 4–27 wt% cobalt loadings were prepared by incipient-wetness impregnation and used to catalyze the synthesis of monoisopropylamine by the reductive amination of 2-propanol in the presence of hydrogen and ammonia. The catalysts were characterized by X-ray diffraction, H 2 -temperature programmed reduction, N 2 -sorption, and H 2 -chemisorption. 23 wt% Co loading resulted in the highest catalytic activity and a long-term stability of up to 100 h on stream. 2-Propanol conversion was related to the exposed metal surface area and the number of exposed cobalt atoms. In the absence of hydrogen, the catalyst was progressively deactivated; its initial activity and selectivity were completely recovered upon re-exposure to hydrogen. The deactivation was due to the formation of metal nitride caused by the strong adsorption of ammonia on the surface of the metal phase. Excess hydrogen hindered the phase transition to metal nitride, preventing deactivation.
TL;DR: Identification of these ammonia oxidizers indicates that the Nitrosomonas europaea/eutropha-like ammonia oxidizing bacteria were responsible for ammonia oxidation instead of other groups of ammonia oxidizer during aerobic treatment of fine organic fraction of municipal solid wastes.
TL;DR: In this paper, the authors compared electrochemical removal of nitrogen from synthetic solutions of fresh and stored urine using IrO2 anodes and showed that the presence of carbonate, arising from urea hydrolysis, leads to an inhibition of ammonia oxidation.
Abstract: Recent studies have shown that electrolysis can be an efficient process for nitrogen removal from urine. These studies have been conducted with urea solutions or fresh urine, but urine collected in NoMix toilets and urinals has a substantially different composition, because bacteria hydrolyse urea quickly to ammonia and carbonate. In this study, we compared electrochemical removal of nitrogen from synthetic solutions of fresh and stored urine using IrO2 anodes. We could show that in fresh urine both ammonia and urea are efficiently eliminated, mainly through chlorine-mediated oxidation. However, in stored urine the presence of carbonate, arising from urea hydrolysis, leads to an inhibition of ammonia oxidation. We suggest two parallel mechanisms to explain this effect: the competition between chloride and carbonate oxidation at the anode and the competition between chlorate formation, enhanced by the buffering effect of carbonate, and ammonia oxidation for the consumption of active chlorine in the bulk. However, further experiments are needed to support the latter mechanism. In conclusion, this study highlights the negative consequences of the presence of carbonate in urine solutions, but also in other wastewaters, when subjected to an electrolytic treatment on IrO2 in alkaline media.
TL;DR: The results indicate that the methane oxidation activity in paddy soils might be inhibited when the concentration of ammonium fertilizers is high and that the interactions between ammonia and methane oxidizers need to be further investigated.
Abstract: Nitrogenous fertilizers are generally thought to have an important role in regulating methane oxidation. In this study, the effect of ammonium on methane oxidation activity was investigated in a paddy soil using urea at concentrations of 0, 50, 100, 200 and 400 μg N per gram dry weight soil (N/g.d.w.s) and ammonium sulfate at concentrations of 0, 50 and 200 μg N/g.d.w.s. The results of this study demonstrate that urea concentrations of 200 μg N/g.d.w.s. and above significantly inhibit methane oxidation activity, whereas no statistically significant difference was observed in methane oxidation activity among soil microcosms with urea concentrations of less than 200 μg N/g.d.w.s after incubation for 27 days. Similar results were obtained in a sense that methane oxidation activity was inhibited only when the ammonium sulfate concentration was 200 μg N/g.d.w.s in soil microcosms in this study. Phylogenetic analysis of pmoA genes showed that nitrogen fertilization resulted in apparent changes in the community composition of methane-oxidizing bacteria (MOB). Type I MOB displayed an increased abundance in soil microcosms amended with nitrogenous fertilizers, whereas type II MOB dominated the native soil. Furthermore, although no statistically significant relationship was observed between pmoA gene and amoA gene abundances, methane oxidation activity was significantly negatively correlated with nitrification activity in the presence of urea or ammonium sulfate. Our results indicate that the methane oxidation activity in paddy soils might be inhibited when the concentration of ammonium fertilizers is high and that the interactions between ammonia and methane oxidizers need to be further investigated.
TL;DR: In this paper, the authors evaluated ammonia as a carbon dioxide (CO2) solvent for post-combustion carbon capture, focusing on the thermal performance of the ammonia regeneration process and the operating conditions for the aqueous ammonia process.