SU1096201A1 - Method of recovering bromine - Google Patents

Abstract

A method of extracting bromine from the bromide mixture, including absorption of bromine with an aqueous solution of a quaternary ammonium salt and subsequent desorption, characterized in that, in order to increase the degree of extraction of bromine, the process is simplified by eliminating the stage of separating the bromine complex from the aqueous phase and making it cheaper, as a quaternary ammonium moles use symmetric fatty ammonium salts of the general formula Bi TRi vg 1 1 where R-, - Cz, -C-alkyl or asymmetric fatty or fatty-aromatic quaternary ammonium salts of the general formula ® Вг В | 1 Hg Rf (L ij with where RRR, -ethyl, 1, R-alkyl with .1,3, -5.7 carbon atoms or § RI R2 R -methyl, R -heptyl or methyl, R-ethyl, R -phenyl, or quaternary salt of N-ethylpyridinium of the formula from O5 to Br

Description

The invention relates to the technology of inorganic substances and can be used to extract the material from the bromo-air mixture obtained by blowing bromine with air from the oxidized bromine-containing brines. A known method for extracting bromine from a bromine-containing mixture involves the absorption of bromine with a solution of bromine-bromine iron, the reduction of bromine iron with iron filings, and the subsequent release of bromine from a solution of iron bromide with chlorine Cl1. The disadvantages of this method are large product losses (up to 4%), as well as a significant amount of unrealizable waste in the form of dilute solutions of ferric chloride and sludge, which pollute the environment. The closest in technical essence and the achieved result is a method of extracting bromine from a bromo-air mixture, including the absorption of bromine with an aqueous solution of quaternary ammonium salts selected from the group of asymmetric quaternary ammonium base compounds with a saturated cyclic nitrogen atom bound to carbon atoms and forming five and a six-membered ring structure, salts of piperidine, pyrolidine and morpholine, the formula of which

where X is CC, R; R is methyl; Kg is an alkyl or haloalkyl group with 1-8 carbon atoms; K is hydrogen or an alkyl group with 1-4 carbon atoms; with R N, Yad5 R. The liquid stream, saturated with bromine vapors, interacts with aqueous solutions of these quaternary ammonium salts at 15-25 ° C to form a liquid polybromide that is not displaceable with water (at 10-60 ° C) and contains 20-70% bromine bromine. The water-immiscible bromine complex is separated and desorbed by bromine with an inert gas t23. The disadvantages of this method are the low recovery rate of bromine from saturated bromo-air mixture (recovery rate is 70.5%, from diluted 42.7%), the complexity of the process associated with the need to separate the bromine complex from the aqueous phase, and the high cost of the process from - for the use of expensive absorbents. The purpose of the invention is to increase the degree of extraction of bromine (74.2-97.2% from the bromo-air mixture, from 50.0-81.7% diluted), to simplify the process by eliminating the stage of separating the bromine complex from the aqueous phase and reducing its cost. calling for cheaper absorbents. The goal is achieved by the fact that, according to the method of extracting bromine and plant growth, and four quarters where either arom or where or or bromo-air mixture consists in absorption of bromine by a water thief of a quaternary ammonium salt of the next desorption, the emric ammonium salt is used as the ammonium salt. ammonium salts of the general form of RR — C — alkyl alkyl asymmetric fatty or fatty quaternary salts of the ammo-general formula 2 H Rj 2 Кз зтил; alkyl with 1.3 to 5.7 carbon atoms, R 2 R 2 -g methyl; R4-heptyl R H2-methyl; I have hemmed; R-Fens, Quaternary salt of N-methyl-pyridine formula 3109 The method is carried out as follows. 1 M concentrations of absorbents (20-40% solutions depending on the molecular weight of the starting salt) are used for absorption. The resulting bromine complexes are insoluble in water and, depending on the temperature of the solution and the starting ammonium salt, can be liquid or solid. Most of them are solid at 30 ° C. The formed complexes contain 40-80 wt.% Bromine, however, the most stable complexes form, when the molar ratio is reached, a quaternary ammonium salt: molecular bromine 1: 1-2 (40-53 wt.% Bromine), depending on the starting ammonium salt then, the surface adsorption of bromine occurs, Sz, by which the bromine in the complex is held weaker, entrains air flow and bromine slip occurs. The airborne mixture is passed through the absorbed solution until complete binding of the quaternary ammonium salt in the complex, which is determined by the absence of bromine ion in the aqueous phase. To ensure 100% recovery of bromine from the bromo-air mixture, it is passed successively through three absorbers with an absorption solution, at a rate of 0.3-0.5 l / min. Increasing the speed shortens the contact time of the phases, does not provide complete extraction of bromine, and requires an increase in the number of absorption steps. Bromine is desorbed from the complex by blowing through the absorption solution.

water vapor or hot air at 70-90 ° C, followed by condensation of molecular bromine.

The strongest complex is tetrabutylammonium bromide, the desorption of bromine from which is carried out with superheated water vapor at 180–200 ° C.

After desorption of bromine, the solution does not lose its absorption properties and is returned to the absorption stage.

Solid bromine complexes are fairly stable under normal conditions. If necessary, they are isolated, dried and.

where R ,, - C. | -alkyl (methyl) (example 1), does not increase the degree of absorption of bromine in comparison with the prototype, the same happens when using triethylhexyl ammonium bromide (example 9) and trimethyl ethyl methyla. Research Institute of bromide (example 11) where the degree of extraction of bromine from the diluted bromo-air mixture is lower than in the prototype.

In tab. 2 shows the comparative data on the cost of absorbents used in the prototype and in the proposed method. stored as dry compounds, from which bromine is isolated in the presence of water by the above methods. Example 1. A 30 ml solution containing 6.3 g (0.03 mol) of tetraztilammonium bromide is placed in a drexel and the bromide-air mixture is passed through, maintaining the temperature not higher than 25 s. Bromine is complexed with an ammonium salt to form a water-insoluble orange compound in the form of flakes. The drexel with the solution is periodically weighed, the air-to-air mixture is passed to a constant weight of the absorption solution. The complex takes on a brick color and becomes liquid. The weight gain due to absorption of bromine is 27.2 g. Hot air is blown through the absorption solution at 70-80 ° C until the complex is completely decomposed (ensuring the solution and the disappearance of the oily layer). Bromine, enlarged by air, is passed through a drexel with a solution of potassium iodide. The amount of desorbed bromine is determined iodometrically. You are 27.1 g of bromine. In tab. Figure 1 shows data on the recovery of bromine by various quaternary ammonium salts. From tab. 1 it follows that when using symmetric fatty ammonium salt of the general formula p B -, RI E

1 Tetramethylammonium bromide

2 Tetraethylammonium bromide

3 Tetrabutylammonium bromide

4 Tetrapropylammonium

bromide

5 Triethylmethylammonium bromide

Triethylpropylammonium

Table 1

0.03

154.0 4.62

0.03

210.17 6.3

0.03

322.38 9.67

266.0 7.98

0.03

0.03

196.14 5.88

Continued table. one

Proto0,036 47.9 1.2 type 5.8

Continued table. one

70.5

Continued table. one

Source three

Method // - methylmorpholine / V - methylpiperidine Prototype A / tJ -. -methylpiperazine Triethylamine Offered Triethylamine alcohols Trybutilamine-dimethylaniline

Price list № -05-11-45.

table 2

Cost for 1 kg in rub. and cop amine methylpyrrolidine 57-00 240-00 400-00 600-00 27-00 174-00

Claims (1)

METHOD FOR REMOVING BROMINE from a bromine-air mixture, including absorption of bromine with an aqueous solution of a quaternary ammonium salt and subsequent desorption, characterized in that, in order to increase the degree of extraction of bromine, simplify the process by eliminating the stage of separation of the bromine complex from the aqueous phase and its cheapening, as quaternary ammonium moles use symmetric fatty ammonium salts of the general formula bi N Βί where R-] is C ^ -C ^ -alkyl or asymmetric fatty or aromatic quaternary ammonium salts of the general formula where R-, = R ₂ = Rj is ethyl, R _{4 is} alkyl with .1,3, -5,7 atoms carbon or Ri = Rj = R ^ -methyl, D ^ -heptyl or methyl, R ^ -ethyl, P ₄ ~ phenyl, or the quaternary salt of N-ethylpyridinium of the formula C e