Ammonia in water

Ion mobility spectrometers with hydrated proton ion chemistry is exquisitely sensitive to ammonia, and two teams have sought to engineer IMS-based analyzers for ammonia in water. ° In the earlier development, ammonia was thermally purged through a silicone membrane, and the limit of detection in this approach was 1.2 mg/L. The membrane was free of memory effects, and pH was controllable and permitted determination of ammonium ion concentrations. The system was engineered to avoid biofouling. 

In a later study,an ion mobility spectrometer equipped with a corona discharge ion source was used with pyridine as an alternate reagent gas to enhance selectivity and sensitivity for the determination of ammoniacal nitrogen in river and tap water samples. The limit of detection was about 9.2 x 10 pg/mL, and the linear dynamic range was obtained from 0.03 to 2.00 pg/mL. The RSD was about 11%, and analytical results on actual environmental samples compared favorably with the Nessler method. 

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Reaction of arninoacetonitrile hydrochloride with sodium nitrite provides diazoacetonittile (62). The product undergoes a 1,3-dipolar cycloaddition with diethyl fumarate to yield a pyrazoline intermediate, which without isolation reacts with ammonia in water to furnish the pyrazole [119741-54-7] (63) (eq. 14) (43). 

Solution of Gases in Liquids Certain gases will dissolve readily in hquids. In some cases in which the quantities are not large, this may be a practical storage procedure. Examples of gases that can be handled in this way are ammonia in water, acetylene in acetone, and hydrogen chloride in water. Whether or not this method is used depends mainly on whether the end use requires the anhydrous or the liquid state. Pressure may be either atmospheric or elevated. The... 

There are, however, a number of well-known systems in which heat effects definitely cannot be ignored. Examples include absorption of ammonia in water, dehumidification of air with concentrated H9SO4, absorption of HCl in water, and absorption of SO3 in H9SO4. Another interesting example is the absorption of acetone in water, in which the heat effec ts are mild but not neghgible. 

Absorption of a gas in a liqiiid, for example, ammonia in water or carbon dioxide in water. 

The amount of HOCl plus OCl in wastewater is referred to as the free available chlorine. Chlorine is a very active oxidizing agent and is therefore highly reactive with readily oxidized compounds such as ammonia. Chlorine readily reacts with ammonia in water to form chloramines. 

A gaseous emission is to be treated for the removal of ammonia. Table 9.4 provides the stream data. Two scrubbing agents are considered for the removal of ammonia, water, Si, and an inm anic solvent, S2. The absorption of ammonia in water is coupled with the following chemical reaction ... 

Figure 13.9 Coupled-column RPLC-UV (215 nm) analysis of 100 p.1 of an extract of a spiked soil sample (fenpropimoiph, 0.052 mg Kg ). LC conditions C-1, 5 p.m Hypersil SAS (60 m X 4.6 mm i.d.) C-2, 5 p.m Hypersil ODS (150 m X 4.6 mm i.d.) M-1, acetonitrile-0.5 % ammonia in water (50 50, v/v) M-2, acetonitrile-0.5 % ammonia in water (90 10, v/v) flow-rate, 1 ml min clean-up volume, 5.9 ml transfer volume, 0.45 ml. The dashed line represents the cliromatogram obtained when using the two columns connected in series without column switcliing. Reprinted from Journal of Chromatography A, 703, E. A. Hogendoom and R van Zoonen, Coupled-column reversed-phase liquid cliromatography in envir onmental analysis , pp. 149-166, copyright 1995, with permission from Elsevier Science.

Figure 9-78. Temperature rise due to heat of solution, ammonia in water.

FIGURE 10.4 In this molecular portrayal of the structure of a solution of ammonia in water at equilibrium, we see that NH, molecules are still present because only a small percentage of them have been protonated by transfer of hydrogen ions from water. In a typical solution, only about 1 in 100 NH, molecules is protonated. The overlay shows only the solute species. 

The experimental value of Kb for ammonia in water at 25°C is 1.8 X I(T5. This small value tells us that normally only a small proportion of the NH molecules are present as NH4+. Equilibrium calculations show that only about 1 in 100 molecules are protonated in a typical solution (Fig. 10.16). In general, the basicity constant for a base B in water is... 

Here cnh, is the concentration of undissociated ammonia in water. The equilibrium constant for this class of equilibria is often defined in terms of a Henry s Law constant, Xh-... 

Bromocriptine 2 (0.65 g, 1 mmol) was dissolved in 100 ml of dry ethanol and 60 ml of tetrafluoroboric acid / diethylether complex (85 %) was added while stirring. After standing overnight at RT the solvent was evaporated and the raw product isolated by extraction in the system dichloromethane 12% ammonia in water and evaporated to the dry residue. This residue was applied to the chromatographic column (I.D. = 2 cm, lenght = 20 cm) packed with silicagel and eluted with dichloromethane / ethylacetate =1 1. The fractions containing 2 were evaporated to the dry residue and crystallized from alcohol. 

Ammonia is recovered from an air-ammonia gas mixture by absorption into water, using a countercurrent packed column. The absorption of ammonia in water is accompanied by the evolution of heat which causes a rise in the liquid water temperature and hence a change in the equilibrium relationship. The problem and data values are taken from Backhurst and Harker (1990). 

SAQ 6.7 A solution of ammonia in water has a pH of 9. Without using a calculator, what is the concentration of solvated protons and hence what is the concentration of hydroxide ions ... 

Figure 1. Henry s constant for solubility of ammonia in water (O) Clifford and Hunter (A) Macriss (Q) Van Krevelen (V) Frohlich (0) Wells (9) also see...

It is required to separate 1 kg/s (3.6 tonnes/h) of a solution of ammonia in water, containing 30 per cent by mass of ammonia, to give a top product of 99.5 per cent purity and a weak solution containing 10 per cent by mass of ammonia. 

Whilst the solubility of a gas is not substantially affected by the total pressure in the system for pressures up to about 500 kN/m2, it is important to note that the solubility falls with a rise of temperature. Thus, for a concentration of 25 per cent by mass of ammonia in water, the equilibrium partial pressure of the ammonia is 30.3 kN/m2 at 293 K and 46.9 kN/m2 at 303 K. 

The absorption of ammonia in water has been extensively studied by a number of workers. Kowalke el al.<22> used a tower of 0.4 m internal diameter with a packing 1.2 m deep, and expressed their results as ... 

Molstad et al.<21> also measured the absorption of ammonia in water using a tower of 384 mm side packed with wood grids, or with rings or saddles, and obtained KGa by direct experiment. The value of k(,a was then calculated from the following relation based on equation 12.17 ... 

It is difficult to compare the performance of various spray towers since the type of spray distributor used influences the results. Data from Hixson and Scott 33 and others show that KGa varies as G70-8, and is also affected by the liquid rate. More reliable data with spray columns might be expected if the liquid were introduced in the form of individual drops through a single jet into a tube full of gas. Unfortunately the drops tend to alter in size and shape and it is not possible to get the true interfacial area very accurately. This has been investigated by Whitman et a/. 34 , who found that kG for the absorption of ammonia in water was about 0.035 kmol/s m2 (N/m2), compared with 0.00025 for the absorption of carbon dioxide in water. 

Solubility of Ammonia in Water. — Ammonia is very soluble in water. Its solubility decreases with increase of temperature, and, as is of course natural, increases with increase of pressure. The following table for the solubility of ammonia in water is interesting —... 

Pauling scale phys chem A numerical scale of electronegativities based on bond-energy calculations for different elements joined by covalent bonds. pol-iri Skal Pavy s solution analychem Laboratory reagent used to determine the concentration of sugars in solution by color titration contains copper sulfate, sodium potassium tartrate, sodium hydroxide, and ammonia in water solution. pa-vez S3,lu-sh3n Pb See lead. 

Mass transfer controlled by diffusion in the gas phase (ammonia in water) has been studied by Anderson et al. (A5) for horizontal annular flow. In spite of the obvious analogy of this case with countercurrent wetted-wall towers, gas velocities in the cocurrent case exceed these used in any reported wetted-wall-tower investigations. In cocurrent annular flow, smooth liquid films free of ripples are not attainable, and entrainment and deposition of liquid droplets presents an additional transfer mechanism. By measuring solute concentrations of liquid in the film and in entrained drops, as well as flow rates, and by assuming absorption equilibrium between droplets and gas, Anderson et al. were able to separate the two contributing mechanisms of transfer. The agreement of their entrainment values (based on the assumption of transfer equilibrium in the droplets) with those of Wicks and Dukler (W2) was taken as supporting evidence for this supposition. 

NH4CN may be analyzed by heating the salt and trapping the decomposed products HCN and ammonia in water at low temperatures. The aqueous solution is analyzed for cyanide ion by silver nitrate titrimetric method or an ion-selective electrode method and ammonia is measured by titration or electrode technique (Patnaik, P. 1997. Handbook of Environmental Analysis, Boca Raton, FL Lewis Publishers). 

The pH of pure (and also not so pure) water is very sensitive to small concentrations of acids and bases. One drop of concentrated sulphuric acid added to a liter of water will change the pH by 4 pH nnits (from 7 to ca. 3). Solntion pH can be stabilized by a buffer (although there may be cases where a stable pH is not desirable) addition of (not too large) quantities of acid or base to a buffered solution will not affect the pH mnch. Buffers are usually mixtures of weak acids or bases and their salts. A common example in CD is the nse of an ammoninm salt (NH4X ) to control the pH of an ammonia solntion. The equilibrium of ammonia in water is given by... 

If ammonium hydroxide (ammonia in water)—a common complexant for Cd in CD—is added to a suspension of Cd(OH)2, the Cd(OH)2 will redissolve, assuming enough ammonia has been added. How much is enough ammonia This can be calculated from the stability constant of the complex between ammonia and Cd. The equilibrium of this reaction to form the cadmium tetraamine complex is given by... 

Reaction with ammonia and primary and secondary amines can also give two types of products, 0-hydroxyamides or amino acids (equation 49). The amide is obtained from the reaction of 0-propiolactone with ammonia in water, while the amino acid is obtained from the reaction in acetonitrile, both in good yield. 0-Lactones react very generally with both aliphatic and aromatic amines, but the type of product does not correlate with polarity of solvent or basicity of amine. Fortunately, conditions can usually be found for the formation of the desired product. 

Ammino-cupric Iodides.—A solution of ammonia in water docs not dissolve cuprous iodide, but if air be allowed access to the mixture a blue solution is formed, and if the solution be cooled colourless crystals of diammino-cupric iodide separate. From the mother-liquor hydrated tetrammino-eupric iodide may be precipitated by means of alcohol. 

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