Ammonia-sulfur dioxide solution

Water-free inorganic solvents, such as ammonia, sulfur dioxide, and hydrazine, have been tested in terms of their suitability for electrolytic metal deposition. Liquid ammonia is used for a series of electrolytic metal deposition processes. Besides the low boiling point (- 33 °C) of this solvent its toxicity is disadvantageous. It has been reported that group lA and IIA metals, such as hthium, sodium, magnesium, and beryllium can be deposited from solutions based on ammonia as a solvent [45]. However, only thin or incoherent layers are thus produced [43, 44]. Because it is possible to form anions of molybdenum, lead, selenium, and tellmium in anunonia, these elements can be anodically deposited. Thus, deposition of the semiconductor lead selenide has also been achieved with ammonia as a solvent. 

Substituted benzenesulfonamides bearing strongly electron-attracting substituents can be reduced in slightly alkaline solution at the dropping mercury electrode to ammonia, sulfur dioxide, and a substituted benzene (Chapter 23). Saccharin is a compound of this type, and the primary electrode reaction is a cleavage of the carbon-sulfur bond chemical reactions follow the initial cleavage. 

The amount of an evolved gas can be determined by a continuous titration method. A carrier gas removes the evolved gas from the furnace chamber and transports it to an aqueous-absorbing solution where it is continuously titrated. The titrant used will depend on the type of evolved gas to be determined. For example, ammonia is titrated with dilute hydrochloric acid, whereas water is determined by the Karl Fischer method. Compounds that can be determined include water, hydrogen chloride, ammonia, sulfur dioxide, carbon dioxide, and chlorine (80). 

Equilibrium partial vapor pressures over solutions of the ammonia-sulfur dioxide-water system have been reported by Johnstone (1935). His data cover temperatures from 35° to 90°C as well as concentrations in the range likely to be encountered in a cyclic process in which the solution is regenerated by distillation. Johnstone proposed the following equations to predict the partial pressure of sulfur dioxide and ammonia over aqueous solutions ... 

Gas Reduction. The use of a gaseous reduciag agent is attractive because the metal is produced as a powder that can easily be separated from the solution. Carbon dioxide, sulfur dioxide, and hydrogen can be used to precipitate copper, nickel, and cobalt, but only hydrogen reduction is appHed on an iadustrial scale. In the Sherritt-Gordon process, the excess ammonia is removed duting the purification to achieve a 2 1 ratio of NH iNi ia solution. Nickel powder is then precipitated by... 

Ammonium sulfate [7783-20-2], (NH 2 U4, is a white, soluble, crystalline salt having a formula wt of 132.14. The crystals have a rhombic stmcture d is 1.769. An important factor in the crystallization of ammonium sulfate is the sensitivity of its crystal habit and size to the presence of other components in the crystallizing solution. If heated in a closed system ammonium sulfate melts at 513 2° C (14) if heated in an open system, the salt begins to decompose at 100°C, giving ammonia and ammonium bisulfate [7803-63-6], NH HSO, which melts at 146.9°C. Above 300°C, decomposition becomes more extensive giving sulfur dioxide, sulfur trioxide, water, and nitrogen, in addition to ammonia. 

Oxidation of sulfur dioxide in aqueous solution, as in clouds, can be catalyzed synergistically by iron and manganese (225). Ammonia can be used to scmb sulfur dioxide from gas streams in the presence of air. The product is largely ammonium sulfate formed by oxidation in the absence of any catalyst (226). The oxidation of SO2 catalyzed by nitrogen oxides was important in the eady processes for manufacture of sulfuric acid (qv). Sulfur dioxide reacts with chlorine or bromine forming sulfuryl chloride or bromide [507-16 ]. 

The anaerobic reaction of sulfur dioxide with aqueous ammonia produces a solution of ammonium sulfite [10192-30-0]. This reaction proceeds efficientiy, even with a gas stream containing as Httie as 1 wt % sulfur dioxide. The sulfur dioxide can be regenerated at a high concentration by acidulation or by stream stripping of the ammonium sulfite solution, or the sulfite can be made to precipitate and the ammonia recovered by addition of lime (243). The process can also be modified to produce ammonium sulfate for use as fertili2er (244) (see Fertilizers). In a variant of this process, the use of electron-beam radiation cataly2es the oxidation of sulfur dioxide in the presence of ammonia to form ammonium sulfate (245). 

Ammonium bisulfite can be used in place of the sulfur dioxide. The solution is treated with activated carbon and filtered to remove traces of sulfur. Excess ammonia is added and the solution evaporated if the anhydrous crystalline form is desired. The crystals ate dried at low temperature in the presence of ammonia to prevent decomposition (61—63). 

Allied-Signal Process. Cyclohexanone [108-94-1] is produced in 98% yield at 95% conversion by liquid-phase catal57tic hydrogenation of phenol. Hydroxylamine sulfate is produced in aqueous solution by the conventional Raschig process, wherein NO from the catalytic air oxidation of ammonia is absorbed in ammonium carbonate solution as ammonium nitrite (eq. 1). The latter is reduced with sulfur dioxide to hydroxylamine disulfonate (eq. 2), which is hydrolyzed to acidic hydroxylamine sulfate solution (eq. 3). 

Copper-based alloys Ammonia (vapors and solutions) Amines Sulfur dioxide Nitrates, nitrites... 

In many cases, water is a poor scrubbing solvent. Sulfur dioxide, for example, is only slightly soluble in water, so a scrubber of very large liquid capacity would be required. SO2 is readily soluble in an alkaline solution, so scrubbing solutions containing ammonia or amines are used in commercial applications. 

Embrittlement embrittlement and for improperly heat treated steel, both of which give intergranular cracks. (Intercrystalline penetration by molten metals is also considered SCC). Other steels in caustic nitrates and some chloride solutions. Brass in aqueous ammonia and sulfur dioxide. physical environments. bases of small corrosion pits, and cracks form with vicious circle of additional corrosion and further crack propagation until failure occurs. Stresses may be dynamic, static, or residual. stress relieve susceptible materials. Consider the new superaustenitic stainless steels. 

Liquids that form conducting solutions are called ionizing solvents. A few other compounds (ammonia, NH3i sulfur dioxide, S02, sulfuric acid, H2SO<, etc.) are ionizing solvents but water is by far the most important. We will discuss water exclusively but the same ideas apply to the other solvents in which ions form. 

Anon., Univ. Safety Assoc., Safety Newsletter, 1982-1984 A solution of the chloride (120 ml) in toluene (750 ml) was treated (apparently without effective stirring) with excess sodium bicarbonate solution to destroy it. When reaction had ceased, the organic layer was poured into a waste solvent drum. Vigorous evolution of sulfur dioxide and hydrogen chloride then ensued from reaction with ethanol (toluene-soluble) in the waste drum. For destruction of solutions of sulfinyl chloride in water-insoluble solvents, extremely good agitation is necessary to ensure proper contact with a basic reagent. Ammonia is more soluble in toluene than is water, so ammonia solution should be used after bicarbonate treatment to ensure complete destruction. 

Hydrogen sulfide is recovered from the scmbbing solution under vacuum, hence the name. It is then either oxidized with air and the sulfur dioxide used for making sulfuric acid, or converted to elemental sulfur by the Claus process. The process is suitable only for gases not containing ammonia. Developed by Krupp Koppers, Germany. Three units were being built in 1993. 

Many of the undesirable substances present in gaseous or liquid streams form volatile weak electrolytes in aqueous solution. These compounds include ammonia, hydrogen sulfide, carbon dioxide and sulfur dioxide. The design and analysis of separation processes involving aqueous solutions of these materials require accurate representation of the phase equilibria between the solution and the vapor phase. Relatively few studies of these types of systems have been published concerning solutions of weak electrolytes. This paper will review the methods that have been used for such solutions and, as an example, consider the alkanolamine solutions used for the removal of the acid gases (H2S and C02) from gas streams. 

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