Ammonium sulfite solutions, removal

Barium methanesulfonate 447 Pure dimethyl sulfate (126 g) is added slowly to 26% ammonium sulfite solution (600 ml) at 10°. When the dimethyl sulfate has dissolved, crystalline ammonium sulfite (75 g) that has been rubbed to a paste with water (75 ml) is added and the whole is heated on the water-bath for a few hours. Next the mixture is diluted whilst still hot to three times its volume, a small excess of sulfite is destroyed by sulfuric acid, the calculated amount of barium hydroxide is added, and the ammonia is boiled off. The excess of barium hydroxide is carefully removed by sulfuric acid, and the solution is neutralized with barium carbonate and filtered. Evaporating the filtrate yields barium methanesulfonate as residue. 

Both batch and continuous processes employ excess sulfur and operate at 85—110°C. Trace amounts of polysulftdes produce a yellow color which iadicates that all the ammonium sulfite has been consumed. Ammonium bisulfite is added to convert the last polysulfide to thiosulfate and the excess ammonia to ammonium sulfite. Concentrations of at least 70% (NH 2S2 3 obtained without evaporation. Excess sulfur is removed by filtration and color is improved with activated carbon treatment or sodium siUcate (66). Upon cooling the aqueous concentrated solution, ammonium thiosulfate crystallines. 

Technical Observations. The solution of ammonium sulfite formed by the action of ammonia on anthraquinonesulfonic acid has a deleterious action on the end product. The sulfite must be removed, therefore, by oxidizing it to the sulfate. 

Ammonia scrubbing is one of many processes for removing sulfur dioxide from flue gases. The gases are bubbled through an aqueous solution of ammonium sulfite, and the SO2 reacts to form ammonium bisulfite ... 

Alkaline hydrolysis of starch nitrate produced ammonia, cyanides, nitrites, and nitrates.1478 Starch nitrate could be denitrated by use of diluted solutions of ammonium sulfite followed by the addition of hydrogen peroxide to remove colloidal sulfur.1448 The strong nitrate band absorption in the infrared between 730 and 960 cm-1 complicates the identification of polysaccharides. The region suitable for identification of starch nitrates is between 900 and 1350 cm M479 Nitration of glyceryl starch into a trinitrate was also reported.1480 Starch nitrates readily react with an TV.TV-dimethylformamidc-SO complex to give trisulfates.1481... 

Hemilian341 used ammonium sulfite on heating ethyl iodide (20 g) with a solution of crystalline ammonium sulfite (20 g) in water (40 ml) he obtained, after cooling, ammonium ethanesulfonate. To convert this into the barium salt he diluted it with water and heated it with lead oxide until evolution of ammonia ceased he filtered the mixture and removed the lead from the filtrate by hydrogen sulfide after renewed filtration he digested the filtrate with barium carbonate, filtered again, and evaporated that filtrate to dryness. 

The use of the DC/DA system adds 10%-15% to the cost of the plant in comparison with the older singleabsorption process. It also uses more energy and produces less steam or other recoverable energy. The residual quantities of SO2 can also be removed by scrubbing the stack gases with an ammonia solution. The resultant ammonium sulfite/bisulfite solution is then acidulated with sulfuric acid to produce ammonium sulfate and SO2. 

The crude trinitrotoluene is worked up by washing with water and soda solution or with sodium sulfite solution to remove the less stable asymmetric isomers which lower the crystallizing point of 2,4,6-TNT. The electron-withdrawing effect of the nitro groups of the asymmetric isomers facilitates nucleophilic substitution by OH or HSO3 groups, even at ambient temperature, so that the reaction products are water-soluble. The crystallizing point of the purified TNT should be at least 80.6 °C. When mixed with 20% aluminum, TNT is marketed under the trade name Tritonal , and when mixed with 50% ammonium nitrate, it is sold under the trade name Amatol . 

Major matrix components or other trace organic compoimds, such as polycyclic aromatic hydrocarbons (PAH) and pesticides, are coextracted with PCBs and might cause interference to the instrumental response, thus they should be eliminated by suitable cleanup procedures. The cleanup is generally performed by column chromatography on suitably activated or deactivate silica [24,54,68,97,128,138,146], sulfuric acid impregned silica [131], alumina [9,14,15,90-92,142], or Florisil (synthetic magnesium silicate) [24,44,67,83], and styrene-divinylbenzene resin [121]. Multilayer columns are frequently utilized. The retention of analytes in the column should be checked by standard solutions in order to find both the best solvent or mixture of solvents and the optimum volume to be used to selectively elute PCBs and leave interferents in the column. n-Hexane and dichloromethane are the most widely used solvents to elute the PCBs from the stationary phase. In addition, special treatments are very often used to eliminate specific interfering substances. For instance, activated copper powder with [23] or without mercury [14,49,81,87,151] or tetrabutyl ammonium sulfite [4] is used to remove elemental sulfur and sulfuric acid is used to remove lipids [107]. 

In the basic form of the Katasulf process, the gas was first passed through an electrostatic filter for tar removal and then preheated to 750°F by heat exchange with the gas leaving the catalytic converter. After addition of air, the gas was admitted to the catalyst chamber where the H2S was converted to SO2. Because of the exothermic nature of the reaction, the gas temperature increased considerably in the converter. The exit gas was partially cooled by heat exchange with the incoming gets. It was then passed through an absorption lower where ii was washed countercurrently with a concentrated aqueous ammonium sulfite-bisulfite solution, which absorbed both the SO2 and NH3. 

Calcium thiosulfate has been prepared from calcium sulfite and sulfur at 30—40°C, or from boiling lime and sulfur in the presence of sulfur dioxide until a colorless solution is obtained. Alternatively, a concentrated solution of sodium thiosulfate is treated with calcium chloride the crystalline sodium chloride is removed at low temperature. Concentrated solutions of calcium thiosulfate are prepared from ammonium thiosulfate and lime the Hberated ammonium ion is recycled to the ammonium thiosulfate process (85). 

Solutions containing ammonium sulfate, with or without the addition of ammonium hydroxide, have been widely used. The ammonium system can operate effectively only within a pH range of 4.0 to 7.0. As the pH value increases above 7.0, progressively more gaseous ammonia is liberated and this reacts in the gaseous phase with water vapor and SO2 to produce a dense aerosol (white plume) which is difficult for scrubbers to remove. In an ammonia system, in order to regenerate the scrubbing solution, the ammonium bisulfite and sulfite mixture is heated... 

The intensity of the color developed is proportional to the amount of phenan-throline complex formed, which is proportional to the concentration of sulfite in the sample. After removing the excess ferric iron with ammonium bifluoride, the absorbance is measured at 520 nm. The concentration of S032- in the sample is calculated from a sulfite standard calibration curve. Because S032- solutions are unstable, the concentration of working standard is accurately determined by potassium iodide-iodate titration before colorimetric measurement. 

Although it is possible to convert the SO2 removed from the flue gas to ammonium sulfate, sodium sulfate, or gypsum, the market for such by-products is quite restricted. More recently, interest has centered on processes that recover the SO2 in concentrated form. One such system, the Wellman Lord Process (licensed by Davy-McKee/Davy Corp. Pic.) uses a solution of sodium or potassium sulfite to absorb SO2. The liquid effluent contains a mixture of sulfites and bisulfites from which the less soluble bisulfites are crystallized. The recovered solids are heated to decompose the bisulfites to sulfites with the release of SO2. These sulfites then are redissolved in the liquid recycled to the scrubber. Only a... 

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