SU981209A1 - Process for decomposizing alkali metal azide - Google Patents

Description

The invention relates to chemical technology, in particular, to a method for the destruction of waste water containing inorganic azides, which are formed in the production of azido compounds used as industrial semi-finished products in organic chemistry, in the manufacture of pharmaceuticals and explosives.

There is a known method for the decomposition of an alkali metal azide by oxidation with nitrite in the presence of strong acids. Moreover, under actual conditions, this reaction is most often carried out by draining an excess of sulfuric or nitric acid into a neutral solution of sodium azide containing an excess of nitrite. rub l.

The disadvantages of this method are as follows: the danger of the process in connection with the possibility of the appearance in the gas phase of nitrous hydrochloric acid, which is highly sensitive to mechanical effects (by its nature, this initiating explosive), in the course of the reaction nitrous oxide, which is It is a toxic substance, f, the process is technologically complex and has a complex instrumentation design.

The closest to that proposed with the technical essence and the achieved result is a method for the decomposition of azide, according to which the azide is treated with calcium persulfate and the process is carried out in a neutral or acidic medium at 45-50 ° C 2.

However, by a known method, the reaction does not pass until the end (i.e., the azide does not completely decompose) at very low concentrations of the reacting components at low temperatures, at which the decomposition proceeds at a very low speed. Conducting the reaction in a neutral or acidic environment can lead to the formation of hydrozoic acid, which

20 is undesirable due to the high possibility of its explosion and, consequently, the danger of the process.

The aim of the invention is to accelerate and safeguard the process.

This goal is achieved by the fact that according to the decomposition method of alkali metal azide, the treatment is carried out with potassium persulfate at 7030 in the presence of alkali. Azi of alkali metal, persulfur potassium to alkali ispol-euyut in m lbnbm ratio, respectively, equal to l (0.55-0.60): (0.1-0.2). Conducting the process in weakly alkaline solutions eliminates the possibility of the release of hydratic acid. The process also eliminates the formation of gaseous toxic products. The main products of the reaction are gaseous nitrogen and small amounts of oxygen. The choice of the temperature of the process is due to the following: at a temperature below, the decomposition of azide proceeds very slowly (more than 6 hours and at temperatures above 90 ° C the gaseous reaction products formed lead to a sharp foaming of the reaction mass and the possibility of its release from the apparatus. Introduction potassium (from stoichiometric is necessary to complete the oxidation process. The introduction of alkali is carried out to neutralize the sulfuric acid produced by the side reaction of potassium persulfate In addition, during the oxidation of waste water solutions (after the preparation of organic azides containing cobalt salts, sodium chloride may react with potassium persulfate to form free chlorine, which is bound to sodium chloride or sodium chlorate. Example 500 ml of a 1.5% aqueous solution of sodium azide containing 12% sodium chloride (7.5 g 60 g NaCI) are charged to the reactor, 18.7 g potassium persulfate are poured, and 1.1 g sodium hydroxide are added. The mixture is heated before gaseous products are released. The reaction time is 28 minutes, the pH of the solution after the end of the process is 7-8. The absence of azide ion is confirmed by a qualitative reaction with FeCIj. The basic data of subsequent experiments performed similarly to the example are presented in Table. 1. The data obtained when carrying out the process using a solution containing 1.5% 15% NaNO, is presented in Table. 2. The data obtained when conducting npoixecca using a solution containing 0.5-1.5% NaN without admixture of other salts is given in table. 3. The use of the proposed technical solution in comparison with the known methods of decomposition of inorganic azides provides a more complete and safe decomposition ((destruction; waste of inorganic azides. In all experiments no traces of nitrous hydrochloric acid and other harmful emissions were detected. The implementation of the proposed method shows its high efficiency, reliability, safety and simplicity. Table

10 10 20 10 10 20 10 20

70 70 70 80 80 80 90 90

one

more than 300

10 20 300

6-7 280

7-8

one .

40

10 20 10

55

6-7

50

7-8

60

3-4 20

35

7

table 2

Table 3

Claims (2)

Claim 1. The method of decomposition of an alkali metal azide by treating it with potassium persulfate at an elevated temperature, characterized in that, in order to accelerate and safe the process, the treatment is carried out at 70-90 ° C in the presence of alkali. 2. The method of pop. 1, distinguished by the fact that alkali azide metal, potassium persulfate and alkali 50 are used in a molar ratio, respectively, equal to 1: (0.55-0.69):: (0.1-0.2).