Showing papers on "Ammonia published in 1981"

Ammonia and Nitrous Oxide Losses Following Applications of Ammonium Sulfate to Flooded Rice

Abstract: Ammonia volatilization from applications of ammonium sulfate to a wet season crop of flooded rice in the Philippines was measured directly by a micrometeorological technique. Prior to transplanting the rice, ammonium sulfate (80 kg nitrogen ha-1) was broadcast over the flooded soil and incorporated by harrowing. A further 40 kg nitrogen ha-1 was broadcast at the panicle initiation stage. The soil pH was 6.7, while the pH of the floodwater varied from 7 . 5 to 9.5 during the course of the experiment. Loss of ammonia was detected immediately after application of ammonium sulfate and continued for approximately 7 days. Ammonia volatilization rates were highest in the middle of the day and declined each evening following the diurnal variations in water temperature and wind speed. More ammonia was lost from the fertilizer applied at the panicle initiation stage (10.6%) than from the pre-planting application (5.1 %). The overall measured loss of ammonia was small and amounted to approximately 7 % of the total nitrogen applied to the crop. Nitrous oxide losses, measured with a chamber system, amounted to only 0.1 % of the nitrogen applied as ammonium sulfate.

The importance of ammonia in proteinaceous attractants for fruit flies (Family: Tephritidae)

Abstract: The responses of the Queensland fruit fly to food-based lures were studied, with particular emphasis on the importance of ammonia as an attractant or repellent. Certain solutions of ammonium bicarbonate were found to be highly effective attractants for the Queensland fruit fly, provided they were tested in traps in which the retention of the flies did not depend on their contacting the bait solution. The attractancies of such solutions were found to be strongly dependent on concentration and pH, and mean attractancies more than five times that of the commercial protein hydrolysate used as a standard were obtained. Highest attractancies were associated with ammonia evolution rates in the region 5-25 ¦l ammonia (s.t.p.) h-1 100 ml-1 of solution; rates above 400 ¦1 ammonia (s.t.p.) h-1 100 ml-1 appeared to be repellent. The addition of a mixture of amino acids to the ammonium bicarbonate solutions under these trap conditions had no significant effect on their attractancy; but the addition of the standard protein hydrolysate to a 0.001 M solution of ammonium bicarbonate, with pH adjusted to 8.5, produced an outstandingly effective lure, with a mean attractancy almost nine times as great as the standard hydrolysate alone at its normal pH of 4.8. Subsequent experiments showed that simply raising the pH of the standard protein hydrolysate to 8.5 caused a similar high attractancy, which could be due in part to the marked rise in ammonia production from endogenous sources. Protein hydrolysate solutions showed pronounced increases in both ammonia production and fruit fly attractancy when microorganisms were allowed to flourish. No such increases occurred when the microorganisms were inhibited with a preservative. Evidence is also presented which indicates that carbon dioxide is mildly repellent to the Queensland fruit fly.

Structure sensitivity in the iron single-crystal catalysed synthesis of ammonia

Abstract: There have been many investigations of the kinetics of the iron-catalysed synthesis of ammonia and the details of the mechanism of its reaction1–3. However, we report here the first direct and, therefore, unambiguous measurement of the surface structure sensitivity of the iron-catalysed ammonia synthesis reaction using the (111), (100) and (110) crystal faces of iron and operating at pressures approaching those used industrially (20 atmospheres). The Fe(111) face was found to be the most active, the activity ratio being 418:25:1 for the Fe(111), Fe(100) and Fe(110) planes. We have also observed the formation of a strongly bound nitrogen species after the reaction, in the presence of which ammonia continues to be produced.

High salinity acclimation by the prawn macrobrachium rosenbergii uptake of exogenous ammonia and changes in endogenous nitrogen compounds

Abstract: The freshwater prawn Macrobrachium rosenbergii was subjected to a hyperosmotic transfer from 0‰to 24‰ salinity. Changes in ammonia excretion, blood Na+, pH, protein, free amino acids (FAA), and ammonia were monitored for 48 h. Following a rapid reduction in ammonia excretion after transfer, ammonia concentrations in exposure water declined for 24 h. These losses could not be attributed to bacterial growth or aerial diffusion. Also during the first 24 h, blood Na+ increased from 150 to 280 mM, still far below ambient Na+ concentrations of 366 mM. Blood ammonia decreased nearly five-fold and protein concentrations in blood declined about 40 g/l. These data may indicate a reversal of normal Na+/NH+4 exchange following a hyperosmotic shock, such that blood Na+ is hyporegulated using exogenous NH+4 as a counter-ion. During the first 24 h after transfer, net ammonia acquired by uptake could be used to increase intracellular ammonia concentrations as a prelude to increased synthesis of FAA. This model may compli...

Ammonia excretion in the seawater blue crab Callinectes sapidus occurs by diffusion, and not Na+/NH+4 exchange

Abstract: A series of experiments was conducted to investigate whether ammonia is excreted across the seawater-acclimated blue crab's gills as ionized NH 4 + or as the free base, NH3. The net excretion rate of ammonia was not changed by transfer of the crabs to reduced (150 mM) Na+ solutions, by transfer to Na+- and K+-free artificial sea water, or by the sodium transport inhibitor amiloride. Ammonia excretion, therefore, does not appear to be linked to Na+ uptake in these animals, and appears to take place by passive diffusion. Since ammonia could diffuse either as NH 4 + or NH3, we examined two other kinds of evidence. The trans-epithelial potential was measured in sea water and the various artificial media. In spite of a 10 mV more negative potential in Na+-, K+-free medium, the ammonia excretion was not reduced. Also, in alkalinized seawater in which the partial pressure gradient of NH3 was reduced, but the concentration gradient of NH 4 + increased, ammonia excretion was reduced by about 70%. These results are consistent with the conclusion that ammonia excretion takes place by diffusion of the free base, NH3.

Free Amino Acids

Abstract: Ninhydrin deaminates amino acids liberating ammonia and gets reduced to hydrindantin. The liberated ammonia condenses with hydrindantin to form a violet coloured compound diketohydrindylidenediketohydrindamine (DYDA) at pH 5.0. Potassium cyanide prevents the oxidation of the reduced hydrindantin. The intensity of violet colour is directly proportional to the amount of amino acid (Yemm & Cocking, 1955).

Phosphine producing pesticide and method of manufacture therefor

Abstract: A pesticide composition comprising a particulate hydrolyzable metal phosphide is rendered liquid phase water repellent by treating particles of the composition with a silicon-organic compound. The silicon-organic compound has at least one reactive moiety, preferably hydrogen capable of reacting with and binding to reactive sites contained on surfaces of particles of the composition. Preferably, the reactive group is hydrogen and the reactive site is a hydroxy group. The silicon-organic compound can also undergo cross-linking reactions. In the water-repellent treatment the silicon-organic compound may be applied to and be reacted to become bonded to any of the solid ingredients of the composition, including urea which serves as a self-ignition inhibitor. Preferably at least part of the silicon-organic compound is bonded to particles of the metal phosphide. Advantages result if all the silicon-organic compound is thus bound to the metal phosphide. On the phosphide surfaces novel metal-silicone compounds may form. The treatment protects the phoshide against access of liquid state water and resulting violent reaction, without inhibiting the access of water in its gaseous state (e.g. atmospheric moisture) required for the generation of phosphine when the composition is used as a fumigant. The hydrophobing reaction of the silicon-organic compound, e.g. polymethyl hydrogen siloxane is promoted by heat or catalysts (metal organic compounds, bases, e.g. ammonia, ammonium compounds, amines). The composition in powder form (enclosed in gas permeable sachets) or in tablets may contain additives, e.g. self-ignition inhibitors such as ammonium carbamate, ammonium carbonate and urea.

Heterogeneous photosynthetic production of amino acids at platinum/titanium dioxide suspensions by near ultraviolet light

Abstract: Studies of the previously reported production of amino acids (glycine, alanine, serine, aspartic acid, glutamic acid) from methane, ammonia, and water in contact with irradiated suspensions of Pt/TiO, were extended. Products were analyzed by LC, HPLC, and coupled GC/mass spectroscopy. Analysis of product mixtures also shows the presence of MeOH, EtOH, and CH3NH2 as products of the photoprocess. Experiments with nitrogen-15 labeled ammonia showed that the nitrogen in the amino acids originated with the N H 3 rather than from contaminants. Amino acids were also produced from the CH4-NH3-H20 mixture during decomposition of hydrogen peroxide at Pt foil. A mechanism for the reaction based on free-radical reactions initiated by hydroxyl radical produced at the irradiated catalyst is proposed. A previous communication from this laboratory' described the production of amino acids by xenon lamp irradiation of platinized TiOz powders (Pt/TiO,) suspended in aqueous ammoniacal solutions saturated with methane. The process apparently occurs by a photosynthetic (energetically uphill) reaction driven by the absorption of the near-ultraviolet (A e405 nm) radiation by the TiO,. These reaction conditions for amino acid formation from a simple reducing mixture are mild compared to previous methods for amino acid production that involved electrical discharge or very short wavelength radiation.2

Release and refixation of ammonia during photorespiration

Abstract: Photorespiratory ammonia metabolism in isolated spinach (Spinacia oleracea L. cv. Viking II) mitochondria was measured using a selective ammonia electrode. The mitochondria showed high rates of ammonia production in the presence of glycine. The isolated mitochondria contained less than 0.02% of the glutamine synthetase activity present in the original homogenate and no significant reassimilation of the released ammonia could be observed with added glutamate or α-ketogluterate. Exogenous added glutamine synthetase did reassimilate the released ammonia. In a recombinated system, with a chlorophyll to mitochondrial protein ratio equal to the ratio in vivo, chloroplasts could very effectively reassimilate the ammonia released in the mitochondria during oxidation of glycine.

Conversion of fixed nitrogen to N2 in rich combustion

Abstract: Equilibrium considerations indicate that the concentration of total fixed nitrogen species (other than molecular N 2 ) should reach a minimum under fuel rich combustion conditions. Increasing the combustion temperature should alleviate the kinetic constraints that prevent the fixed nitrogen concentration from approaching the low values predicted by equilibrium. In this study the concept of fuel rich combustion at high temperatures was explored, and the dependence of fixed nitrogen conversion to N 2 on the equivalence ratio, temperature and reaction time was determined in oxygen-enriched methane/air combustion doped with ammonia or nitric oxide. To maintain constant, high temperature conditions required for the fixed nitrogen to N 2 conversion, a tubular flow reactor with its walls heated to the adiabatic temperature of the premixed flames supplied by a flat flame burner was used for these reaction studies. The results indicate the validity of the concept of minimizing fixed nitrogen species (HCN+NH 3 +NO) concentration by increasing the temperature in the range of 1850 K to 2050 K at the optimum equivalence ratio of 1.7–1.9. The predominant initial nitrogen species is HCN which is converted to N 2 presumably through amine and NO intermediates. A comprehensive treatment of the mechanism of nitrogen chemistry in rich combustion led to a kinetic analysis of the results, which indicates that near the flame front fixed nitrogen conversion to N 2 follows a second order rate law because of the rate controlling nature of bimolecular reactions involving fixed nitrogen intermediates (NH 4 , N, NO). At the same temperatures, but longer reaction times HCN reaction with chain carrier radicals becomes rate controlling, as evidenced by the first order decay of HCN.

Stabilized fumigant composition comprising an aqueous solution of ammonia, hydrogen sulfide, carbon disulfide and sulfur

Abstract: A stabilized fumigant composition comprises an aqueous solution containing up to about fifty percent by weight of a solute which comprises ammonia, hydrogen sulfide and carbon disulfide. Elemental sulfur can also be a component of the solute. One preferred composition comprises a solution wherein the molarity of hydrogen sulfide is about 1.5 times the molarity of carbon disulfide, and is about one-half the molarity of ammonia, and wherein the molarity of sulfur is about 1.6 times the molarity of carbon disulfide. The composition decomposes in a soil environment to form sources of available plant nutrients, including ammonia, hydrogen sulfide and sulfur, and carbon disulfide which inhibits nitrification and decreases the nematode population. Nutrient content can be enhanced by the addition of, for example, ammonia, ammonium nitrate, urea and mixtures thereof to the formed composition. The composition can also be decomposed by dilution or heat application, or both, to yield its components for non-soil fumigation uses.

Catalytic amination process for the production of amines

Abstract: Vapor phase catalytic production of an amine by the reaction of a mixture comprising an olefin having from 2 to 8 carbon atoms and ammonia or ammonia type compound. The formation of polymers is prevented by applying a temperature ranging from 200° to 500°C, a pressure of from 300 to 6.000 psig and an ALUMINO SILICATE, e.g. a zeolite catalyst.

Process for preparing 4-amino-2,2,6,6-tetramethylpiperidine

Abstract: 1 Process for the preparation of 4-amino-2,2,6,6-tetramethyl-piperidine by reacting 2,2,6,6-tetramethyl-piperidin-4-one with excess ammonia and hydrogen in the presence of hydrogenation catalysts at elevated temperature and elevated pressure, characterized in that hydrogenation is effected in the absence of a solvent, with an excess of ammonia of 10 to 50 moles and with hydrogen being forced in at a pressure of 50-500 bar, the temperature being between 120-180 degrees C if the process is carried out continuously and between 180-220 degrees C if it is carried out discontinuously

Process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions

Abstract: An improved process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions thereof by hydrolyzing the urea, and thereafter desorbing ammonia and carbon dioxide. The dilute solution containing urea is passed into the top portion of a reaction column and caused to flow downward and countercurrent to a heating and stripping gas while maintaining the reaction column at a pressure of between about 10 and 30 bar, and a top column temperature of between about 170° and 220° C. and a bottom column temperature of between about 180° and 230° C. The resulting liquid stream removed from the bottom of the reaction column, comprised of a substantially urea-free aqueous solution of ammonia and carbon dioxide, is introduced into a desorption zone wherein, at a pressure of between about 1 and 5 bar, ammonia and carbon dioxide are removed therefrom.

Process for the production of ammonia

Abstract: In a pressure swing adsorption system for the purification of hydrogen to be used in an ammonia synthesis gas, nitrogen is employed as a purge gas at an elevated purge pressure. The hydrogen recovered at adsorption pressure contains about 20-25% nitrogen and is advantageous for use as said ammonia synthesis gas. The purge gas is expanded to generate power that can be used to compress air being passed to an air separation system. The nitrogen recovered therein can be employed as said purge gas, while the oxygen recovered can conveniently be employed in a hydrogen generation system used to form said hydrogen passed to the pressure swing adsorption system.