Ammonium chloride, recovery

Recovery of Ammonia. The filter Hquor contains unreacted sodium chloride and substantially all the ammonia with which the brine was originally saturated. The ammonia may be fixed or free. Fixed ammonia (ammonium chloride [12125-02-97]) corresponds stoichiometrically to the precipitated sodium bicarbonate. Free ammonia includes salts such as ammonium hydroxide, bicarbonate, and carbonate, and the several possible carbon—ammonia compounds that decompose at moderate temperatures. A sulfide solution may be added to the filter Hquor for corrosion protection. The sulfide is distilled for eventual absorption by the brine in the absorber. As the filter Hquor enters the distiller, it is preheated by indirect contact with departing gases. The warmed Hquor enters the main coke, tile, or bubble cap-fiUed sections of the distiller where heat decomposes the free ammonium compounds and steam strips the ammonia and carbon dioxide from the solution. 

This carbon dioxide-free solution is usually treated in an external, weU-agitated liming tank called a "prelimer." Then the ammonium chloride reacts with milk of lime and the resultant ammonia gas is vented back to the distiller. Hot calcium chloride solution, containing residual ammonia in the form of ammonium hydroxide, flows back to a lower section of the distiller. Low pressure steam sweeps practically all of the ammonia out of the limed solution. The final solution, known as "distiller waste," contains calcium chloride, unreacted sodium chloride, and excess lime. It is diluted by the condensed steam and the water in which the lime was conveyed to the reaction. Distiller waste also contains inert soHds brought in with the lime. In some plants, calcium chloride [10045-52-4], CaCl, is recovered from part of this solution. Close control of the distillation process is requited in order to thoroughly strip carbon dioxide, avoid waste of lime, and achieve nearly complete ammonia recovery. The hot (56°C) mixture of wet ammonia and carbon dioxide leaving the top of the distiller is cooled to remove water vapor before being sent back to the ammonia absorber. 

In these cases, the use of weaker acids such as acetic acid or ammonium chloride permits the recovery of the desired alcohol. After the hydrolysis step is complete, the aqueous phase is separated from the organic phase and the product is then isolated. 

The Leblanc process was replaced by the ammonia soda (Solvay - 1860 ) process, in which sodium chloride brine is treated with ammonia and carbon dioxide to produce sodium bicarbonate and ammonium chloride. Sodium carbonate is obtained from the bicarbonate by heating. Ammonium chloride treated with lime gives calcium chloride and ammonia. The chlorine in the original salt becomes calcium chloride that is used for melting snow and ice. The ammonia is reused in the process (99.9% recovery). 

Recovery of acetamiprid, IM-1-2 and IM-1-4. Combine 20 g of the air-dried soil with 100 mL of a mixed solvent of methanol and 0.1 M ammonium chloride (4 1, v/v) in a 250-mL stainless-steel centrifuge tube, shake the mixture with a mechanical shaker for 30 min and centrifuge at 8000 r.p.m. for 2 min. Filter the supernatant through a Celite layer (1-cm thick) under reduced pressure into a 500-mL flask. Add a second 100 mL of mixed solvent to the residue and then extract and filter in the same manner. Combine the filtrates and add 150mL of distilled water with 1 g of sodium chloride. Transfer the aqueous methanol solution into a 1-L separatory funnel and shake the solution with 200 mL of dichloromethane for 5 min. Collect the dichloromethane in a flask and adjust the pH of aqueous methanol to 13 with sodium hydroxide. Extract the solution with two portions of 200 mL of dichloromethane for 5 min. Combine the dichloromethane extracts and pass through a filter paper with anhydrous sodium sulfate. Add 0.5 mL of diethylene glycol and then concentrate the dichloromethane extract to about 0.5 mL on a water-bath at ca 40 °C by rotary evaporation. 

Anhydrous hydrogen chloride gas is used to produce phosphonium chloride, PH4CI, which is a flame retardant for cotton textiles. Other major apphcations include manufacture of a number of high purity metal chlorides, ammonium chloride, chlorosulfuric acid recovery of waste metals preparation of alkyl chlorides and chloroacetic acids and as a chlorinating agent in organic syntheses. 

The contents of the reaction flask are cooled to room temperature (Note 1), and the ammonium chloride which separates is filtered off and centrifuged (Note 2). The mother liquor is concentrated on the steam bath under reduced pressure to 2500 cc., and again cooled to room temperature, whereupon a second crop of ammonium chloride is obtained. The total recovery of ammonium chloride up to this point amounts to 780-815 g. 

The total yield of crude centrifuged methylamine hydrochloride is 830-850 g. This product contains, as impurities, water, ammonium chloride, and some dimethylamine hydrochloride. In order to obtain a pure product, the crude methylamine hydrochloride is recrystallized from absolute alcohol (Note 4). The crude salt is placed in a 5-I. round-bottom flask fitted with a reflux condenser protected at the top with a calcium chloride tube 2 1. of absolute alcohol is added and the mixture heated to boiling. After about half an hour the undissolved material is allowed to settle and the clear solution is poured off. When the alcoholic solution is cooled, methylamine hydrochloride crystallizes out. It is filtered off and centrifuged, and the alcohol used for another extraction. The process is repeated until the alcohol dissolves no more of the product (about five extractions are necessary). In the flask 100-150 g. of ammonium chloride remains, making the total recovery of ammonium chloride 850-950 g. The yield of recrystallized methylamine hydrochloride is 600-750 g. (45-51 per cent of the theoretical amount, based on the ammonium chloride used up in the process). 

Aqueous systems have been used in separations, coatings, and synthesis. Aqueous biphasic systems have been developed for hquid-liquid extractions using water-soluble polymers such as polyethylene glycol, and inorganic salts such as ammonium chloride or potassium phosphate (Rogers et al., 1998), (Sherman et al., 1998). These systems have been investigated for use in the separation and recovery of heavy metals from mixed wastes and in the recovery of colored impurities from textile waste streams (Sherman et al., 1998). 

A method has been developed for the analysis of the fungicide TBZ in fruits, potatoes, and their processed products. Extraction was performed with a basic solution (ethanol with 2 M ammonium chloride, pH 9.5, with 14.5 M ammonium hydroxide) and methylene chloride. Tribendazole was partitioned into methylene chloride with a polytron. No further cleanup was needed. Total analysis time, including extraction, was 25 min per sample. Recoveries ranged from 77 to 135%. Detection limits were 1.0 ppb for juice, fruits, and potatoes and 2 ppb for bulk concentrates (12). 

Cao and Zeng [52] used of an oscillopolarographic method for the determination and the electrochemical behavior of omeprazole. Portions of standard omeprazole solution were treated with 1 ml 1 M ammonia/ ammonium chloride at pH 8.9 and the solution was diluted with water to 10 ml. The diluted solution was subjected to single sweep oscillopolaro-graphy with measurement of the derivative reduction peak at —1.105 V versus saturated calomel electrode. The calibration graph was linear from 0.5 to 10 /iM omeprazole with a detection limit of 0.2 fiM. The method was applied to the analysis of omeprazole in capsules with recoveries of 100-118.6% and RSD of 6.78%. The electrochemical behavior of omeprazole at the mercury electrode was also investigated. 

Recovery of ammonia by treating the ammonium chloride filtrate with quicklime, expelling the ammonia gas to be used again in step 2, and working up the calcium chloride left behind ... 

Write the intersecting ionic equation for the recovery of ammonia from the ammonium chloride liquors. 

Amine Additives. It is precisely in this area, suppressing an undesired product in favor of the desired one, that additives can be most useful. High silica zeolites have been formed in the presence of amine additives. Vaughan (16) has prepared faujasite with 7.0 SiC>2/Al2(>3 (24.52 A0) by addition of bis-(2-hydroxyethyl) dimethyl ammonium chloride in a slurry composition whose cation composition is 69% Na and 31% organic template (T). To scale this product up to commercial synthesis would require almost total recovery of the organic template. But its silica content makes it an interesting candidate for catalytic testing. 

The submitters omitted the extraction of the first residue (which consists of triethylamine hydrochloride, excess ammonium chloride (NH4CI) and amide 4) with THF, but the checkers found this essential in order to obtain the higher yield (88%) reported. To recover all amide 4, it is necessary to repeat the procedure, because the product requires extended periods to dissolve completely. As an alternative work up procedure, the checkers removed the CHCI3 under reduced pressure and stirred the reaction mixture in THF (250 mL containing ca. 5 g of NH4CI) for 1 hr. After filtration of the suspension, recovery of 4 was poor (3.6 g from two recrystallizations). 

FIGURE 31.17 Schemes of the highly selective ligand for uranium recovery from seawater, (a) The hexacarboxylate Ugand (b) after reaction with tri-octyl methyl ammonium chloride. (Reproduced from Tabushi, I., Kobuke, Y., Nakayama, N., Aoki, T., and Yashizawa, A., Ind. Eng. Chem. Prod. Res. Dev., 23, 445, 1984. With permission.)... 

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