KR100695193B1 - Method for producing 2,4,6-trimercapto-s-triazine alkali metal salt - Google Patents

Abstract

(a) Cyanuric chloride (2,4,6-trichloro-s-triazine) may be added to the mixture of alkali metal sulfides, alkali metal hydrides or alkali metal sulfides and alkali metal hydrides in an aqueous medium with 20 to Reacting at a temperature in the 70 ° C. range and at pH (8.5) to (10.5);

(b) acidifying by immediately adding an inorganic acid to the reaction product of step (a) to precipitate 2,4,6-trimercapto-s-triazine (Na ₃ T-H ₃ );

(c) separating the precipitated 2,4,6-trimercapto-s-triazine and dispersing it in an aqueous medium, and then adding an alkali metal hydroxide to alkali the 2,4,6-trimercapto-s-triazine. Obtaining a metal salt; And

(d) evaporating and cooling an aqueous alkali metal salt solution of 2,4,6-trimercapto-s-triazine as a result of step (c) to obtain crystallized 2,4,6-trimercapto-s-triazine. A method for preparing an alkali metal salt of 2,4,6-trimercapto-s-triazine is provided, comprising obtaining an alkali metal salt and isolating it.

The preparation method of the 2,4,6-trimercapto-s-triazine alkali metal salt according to the present invention is simplified by shortening the existing process, minimizing the NaCl content as a reaction by-product, and improving the yield.

Description

Method for preparing 2,4,6-trimercapto-s-triazine alkali metal salt {A method of preparing 2,4,6-trimercapto-s-triazine alkali metal salt}

The present invention relates to a method for preparing a 2,4,6-trimercapto-s-triazine alkali metal salt, which is more simplified than the conventional process, minimizes the NaCl content by reaction, and has an improved yield of 2,4. The manufacturing method of the 6-trimercapto-s-triazine alkali metal salt is related.

The 2,4,6-trimercapto-s-triazine alkali metal salt is used as a heavy metal remover to remove heavy metals contained in various wastewaters.

Due to the development of the industry, the quality of life of human beings can be improved and abundant life can be achieved, but in proportion to this, heavy metal-containing wastewater is generated in various fields such as various factories, incinerators, landfills and university research institutes. If these heavy metals are not properly handled and introduced into nature, they have a devastating effect on the environment, which poses a great threat to humans at the peak of the food chain.

Various heavy metal removers have been developed to remove heavy metals contained in the wastewater, but they have toxic and odorous effects on their own, which requires caution when applied to the site and adversely affects the environment when used excessively.

Legislative measures to regulate heavy metal wastewater discharged into the natural environment are particularly changing rapidly. Aqueous liquids for cleaning (purifying) exhaust gases from various wastewaters from industrial sites, particularly from incinerators of sulfuric acid type industrial emissions, are medium containing heavy metals. Similarly, soil can be contaminated with such metals.

In the field of aqueous liquids for scrubbing exhaust gases from incineration plants, the best known method of removing heavy metals is to produce basic precipitation with lime and then carry out an improved precipitation / separation step, usually by the addition of flocculants. will be.

However, this method has several disadvantages. In particular, a large amount of sludge is generated by precipitation with lime, and such sludge must be buried in a particular landfill after purification and compaction in the form of a cake.

Moreover, the sludge obtained is difficult to stabilize (or immobilize) with the current technology. The presence of large amounts of calcium in the sludge can significantly suppress stabilization (or immobilization) operations such as, for example, stabilization by vitrification. Now, due to the anticipated regulations associated with the storage of the final special waste, it is necessary to stabilize (fix) the cake before placing it in the landfill to substantially reduce the leaching of this type of waste.

In addition, various heavy metal removers such as NaSH, Na ₂ S and HNaS have been developed to remove heavy metals from wastewater. These compounds are mainly sulfur-containing compounds, which are effective for removing heavy metals, but have high toxicity by themselves and their unique odors. Requires attention.

Although these compounds effectively remove heavy metals from the wastewater, they do not only adversely affect the aquatic ecosystem due to their toxic effects in overuse, but they also have low sludge stability when they are left in the open air. Together, heavy metals can be re-dissolved and contaminate soils and water systems.

In order to solve this problem, various alkali metal salts of trimercapto-s-triazine have been developed as environmentally friendly heavy metal removers.

The sodium salt of trimercapto-s-triazine and its trivalent acid has already been described in A.W.Hofmann-Chem. Ber. 18 (1885), 2196-2207.

Trimmercapto-s-triazine alkali metal salts are very toxic and have little effect on the water system, and do not generate odors peculiar to sulfur compounds. Mono, di, and tri-alkali metal salts of trimercapto-s-triazine (hereinafter referred to as Na ₃ T-H ₃ ) have already been developed and commercially produced, and their hydrates in the form of trihydrate, hexahydrate, and nonahydrate have also been developed.

These compounds can be produced by a relatively simple process obtained by reacting 2,4,6-trimercapto-s-triazine (cyanuric chloride) and sodium sulfide, but the yield is low and the process of recycling the filtrate. While undergoing a process such as acidification and alkalizing in, there is a problem that generates a large amount of by-products.

In addition, in the conventional technique for preparing trimercapto-s-triazine alkali metal salt, a large amount of energy is consumed to cool the reaction liquid, and the theoretical yield of the amount of precipitation of the trimmercapto-s-triazine sodium salt solubility in water is high. Since only 70% of the solution is subjected to the process of reprocessing the filtrate, there is a problem that more energy is required by repeating the process of acidification, alkalizing and cooling to improve the yield.

Therefore, the present invention is to solve the problems of the prior art, by eliminating and simplifying some steps of the existing process, by minimizing the NaCl content of the reaction by-products, improving the yield, 2,4,6- trimmer with improved economics It is to provide a method for producing a capto-s-triazine alkali metal salt.

In order to achieve the above object,

(a) Cyanuric chloride (2,4,6-trichloro-s-triazine) may be added to the mixture of alkali metal sulfides, alkali metal hydrides or alkali metal sulfides and alkali metal hydrides in an aqueous medium with 20 to Reacting at a temperature of 70 ° C. and at a pH of 8.5 to 10.5;

(b) acidifying by immediately adding an inorganic acid to the reaction product of step (a) to precipitate 2,4,6-trimercapto-s-triazine (Na ₃ T-H ₃ );

(c) separating the precipitated 2,4,6-trimercapto-s-triazine and dispersing it in an aqueous medium, and then adding an alkali metal hydroxide to alkali the 2,4,6-trimercapto-s-triazine. Obtaining a metal salt; And

(d) evaporating and cooling an aqueous alkali metal salt solution of 2,4,6-trimercapto-s-triazine as a result of step (c) to obtain crystallized 2,4,6-trimercapto-s-triazine. It provides a method for producing an alkali metal salt of 2,4,6-trimercapto-s-triazine, which comprises obtaining an alkali metal salt and isolating it.

According to an embodiment of the present invention, in the step (a) of the production method, the alkali metal sulfide and the alkali metal hydrogen sulfide are Na ₂ S and NaSH, respectively, in the steps (c) and (d), The 4,6-trimercapto-s-triazine alkali metal salt is 2,4,6-trimercapto-s-triazine trisodium salt (Na3T-Na ₃ ).

According to another embodiment of the present invention, the inorganic acid is added in step (b) to acidify to pH 1 to 6.

According to another embodiment of the present invention, in step (b), the inorganic acid is selected from the group consisting of HCl, H ₂ SO ₄ , H ₃ PO ₄ and HNO ₃ .

According to another embodiment of the present invention, the alkali metal hydroxide in step (c) is NaOH or KOH aqueous solution.

According to another embodiment of the present invention, the alkali metal hydroxide in step (c) is included in the mixture of alkali metal sulfides, alkali metal hydrogen sulfides or alkali metal sulfides and alkali metal hydrogen sulfides used in step (a). It is added in an amount that includes at least the number of moles of alkali metal.

According to another embodiment of the present invention, the alkali metal hydroxide is added in step (c) and maintained at pH 11 to 13.

According to another embodiment of the present invention, in the step (d) of the preparation method, the aqueous solution of 2,4,6-trimercapto-s-triazine alkali metal salt is evaporated under reduced pressure, and then cooled to 0 to 20 ° C. .

The preparation method of the 2,4,6-trimercapto-s-triazine alkali metal salt according to the present invention is simplified by shortening the existing process, minimizing the NaCl content as a reaction by-product, and improving the yield.

Hereinafter, the present invention will be described in more detail.

Method for producing an alkali metal salt of 2,4,6-trimercapto-s-triazine according to the present invention,

(a) Cyanuric chloride (2,4,6-trichloro-s-triazine) may be added to the mixture of alkali metal sulfides, alkali metal hydrides or alkali metal sulfides and alkali metal hydrides in an aqueous medium with 20 to Reacting at a temperature of 70 ° C. and at a pH of 8.5 to 10.5;

(b) acidifying by immediately adding an inorganic acid to the reaction product of step (a) to precipitate 2,4,6-trimercapto-s-triazine (Na ₃ T-H ₃ );

(c) separating the precipitated 2,4,6-trimercapto-s-triazine and dispersing it in an aqueous medium, and then adding an alkali metal hydroxide to alkali the 2,4,6-trimercapto-s-triazine. Obtaining a metal salt; And

(d) evaporating and cooling an aqueous alkali metal salt solution of 2,4,6-trimercapto-s-triazine as a result of step (c) to obtain crystallized 2,4,6-trimercapto-s-triazine. Obtaining an alkali metal salt and separating it.

In addition, the inorganic acid added in the step (b) is preferably HCl, H ₂ SO ₄ , H ₃ PO ₄ or HNO ₃ .

In the step (b), an inorganic acid is added, preferably, acidified to pH 1 to 6. More preferably, it is pH 4 or less. When acidified to a level exceeding pH 6, there is a problem that Na ₃ T-H ₃ which is not precipitated and dissolved can remain significantly.

The alkali metal hydroxide added in step (c) is preferably NaOH or KOH.

Preferably, the alkali metal hydroxide added in step (c) includes at least the number of moles of alkali metal contained in the mixture of alkali metal sulfides, alkali metal hydrides or alkali metal sulfides and alkali metal hydrides used in step (a). Add as much as possible.

Preferably, in the method for producing the 2,4,6-trimercapto-s-triazine alkali metal salt according to the present invention, the alkali metal salt is a sodium salt. That is, in step (a), the alkali metal sulfide and the alkali metal hydrogen sulfide are Na ₂ S and NaSH, respectively, and the 2,4,6-trimercapto-s-tree of steps (c) and (d) is performed. The azine alkali metal salt is 2,4,6-trimercapto-s-triazine trisodium salt (Na3T-Na ₃ ). In particular, the 2,4,6-trimercapto-s-triazine alkali metal salt of step (d) can be obtained in the form of trihydrate.

Aqueous solutions of 2,4,6-trimercapto-s-triazine trisodium salt (Na3T-Na ₃ ) are not only commercially useful, but also flue gas wash water, mines in waste incinerators. It is used to remove heavy metals from industrial wastewater and galvanotechnical, chemical plant wastewater. In German patent application DE-AS 22 40 549, the separation of heavy metals, such as Cu, Cd, Ni, Hg, Ag, Pb, into poorly soluble compounds from wastewater using trimercapto-s-triazine or its water-soluble alkali metal salts Is disclosed.

A commercially available aqueous Na ₃ T-Na ₃ solution has a concentration of 15 wt% (TMT 15 data from Degussa, 3/1986). From 0 ℃ water solubility of Na3T-Na ₃ of the saturation concentration is about 16 wt%, and from about 25 wt% when the 20 ℃ (0 ℃ days when water 1L per Na3T-Na ₃ is about 0.78 mole, 20 ℃ day when the solubility of water per 1L Na3T-Na ₃ is about 1.37mole). Therefore, although the solubility of Na ₃ T-Na ₃ increases with increasing temperature, only about 15 wt% of solution is a commercially available pre-solved form.

Solubility of Na ₃ T-H ₃ shows a maximum near pH 10.5-11.

The titration curve for Na3T-H ₃ makes the first rise near pH 7, the second rise near pH 10.5, and the third rise near pH 12.5. As such, the titration curves are sequentially raised to 2,4,6-trimercapto-s-triazine monosodium salt (hereinafter referred to as Na3T-Na), 2,4,6-trimercapto-s-triazine disodium Salts (hereafter Na ₃ T-Na _{2 )} , 2,4,6-trimercapto-s-triazine trisodium salt (Na ₃ T-Na ₃ ), and solubility thereof. That is, Na3T-H ₃ is almost insoluble in water (less than 0.5wt%), whereas Na3T-Na is slightly soluble in water (about 3wt%), while Na3T-Na ₃ has high solubility and is easily soluble in water. If a 2.2 hydrogen atom is substituted for Na ₃ T by Na ions, it means a salt mixture of 80 mole% Na ₃ T-Na ₂ and 20 mole% Na ₃ T-Na ₃ .

Surprisingly, a salt mixture of about 70 mole% Na ₃ T-Na ₃ and 30 mole% Na ₃ T-Na ₂ also exhibits high solubility in water. That is, it has a solubility of about 1.5 mol / liter H ₂ O in 0 ° C. water and 2.0 mol / liter at 20 ° C.

If less than two hydrogen atoms in Na 3 T are substituted with Na ions, Na 3 T—Na precipitates.

The present invention utilizes this property of trimercapto-s-triazine alkali metal salts. In particular, the present invention minimizes the yield and impurities by utilizing the insoluble properties of 2,4,6-trimercapto-s-triazine (Na3T-H ₃ ) in water.

Hereinafter, in order to compare with the 2,4,6-trimercapto-s-triazine alkali metal salt production method according to the present invention, a conventional method for preparing a conventional trimercapto-s-triazine trisodium salt according to the prior art will be described.

In the prior art, as in Scheme 1, prepared by reacting 2,4,6-trimercapto-s-triazine (cyanuric chloride) with NaSH or Na ₂ S, or NaSH, Na ₂ S in an appropriate ratio The mixed mixture was reacted in an aqueous solution at a temperature of 40 to 50 ° C. for at least pH 1 and at least 1 hour. Then, an aqueous NaOH solution was added to adjust the pH to 12.5, followed by reaction for 30 to 1 hour. To separate the trimercapto-s-triazine alkali metal salt.

In the above, while maintaining the pH of about 9 in the process of reacting the cyanuric chloride and NaSH or Na ₂ S, it is later adjusted to pH 12.5 by adding NaOH. This is to all of the hydrogen atoms of at Na3T seen, _H-3 on the titration curve of Na3T _H-3 is the preparation of a Na3T-Na ₃ to be substituted by Na maintain a pH that Na3T-Na ₃ generation.

Synthesis of Na3T-Na ₃ and then cooling, or crystallization by cooling after evaporation and concentration to obtain Na3T-Na ₃ crystals by centrifugation, etc., and hydrochloric acid to separate Na3T-Na ₃ from the filtrate. When added and acidified, Na ₃ T-H ₃ forms crystals, which can be separated, removed and cooled again, or evaporated and cooled to crystallize to separate Na ₃ T-Na ₃ .

However, NaCl is produced as a byproduct in the process of reacting cyanuric chloride with NaSH or Na ₂ S. To remove the NaCl produced by such by-products, Na3T-Na ₃ crystals gave washed with water, there was a disadvantage outgoing washed away as the solubility is high Na3T-Na ₃ In this process, re-processing the filtrate, and to make a decision again It is undergoing evaporation and cooling.

The final product obtained in the above process is Na ₃ T-Na ₃ · 3H ₂ O, the water-containing crystals can be dried in air to obtain the final product.

Hereinafter, in order to explain in more detail the method for producing 2,4,6-trimercapto-s-triazine alkali metal salt according to the present invention, for example, 2,4,6 is a preferred but non-limiting embodiment of the present invention. The manufacturing method of -trimercapto-s-triazine trisodium salt is demonstrated more concretely.

First, as in Scheme 1, cyanuric chloride and NaSH or Na ₂ S are reacted in an aqueous solution for about 1 hour or more while maintaining a temperature of about 40 to 50 ° C. and a pH of about 8.5 to 10.5. The reaction product is cooled to room temperature (about 25 ~ 30 ℃) in a natural state, and immediately added HCl to adjust the pH to 6 or less.

The pH is adjusted to 6 or less in order to suppress the Na 3 T-Na having a certain solubility in water at pH 7 in the titration curve of 2,4,6-trimercapto-s-triazine.

As described above, when the pH is adjusted to 6 or less, Na ₃ T-H ₃ insoluble in water precipitates almost quantitatively. At this time, the process of adjusting the pH to 12.5 by using NaOH in the existing process is omitted, so that a difference occurs with the existing process, and the process in the present invention is simplified.

The quantitatively obtained Na ₃ T-H ₃ crystals were separated and dehydrated by centrifugation, dispersed in water, and NaOH was added thereto to raise the pH to about 11 to 13 to produce Na ₃ T-Na ₃ .

After evaporating the solution in which Na3T-Na ₃ is dissolved under reduced pressure, the Na3T-Na ₃ crystal can be obtained by cooling to 0 to 20 ° C., and the filtrate generated in the filtration process is produced in the following process without any treatment. Combine with ₃ dissolved solution and recycle.

When preparing the mercapto 2,4,6-trimmer -s- triazine sodium salt in accordance with the present invention, NaCl is generated as a by-product because it generated and filtered the insoluble Na3T _H-3 in the first reaction step Na3T-H not only do not like mixed in the _third determination, even with the water in the washing procedure can pass to a process for producing Na3T-Na ₃ without loss of Na3T _H-3.

As a result, in the present invention, it is possible to improve the economics by unifying the processes of manufacturing Na ₃ T-Na ₃ and Na ₃ T-H ₃ in the conventional process.

The following examples illustrate the invention without limiting its scope.

Example  One

200 g (1.427 mol) of 40 wt% NaSH aqueous solution was added to 130 mL of water, and the temperature of the solution was brought to 50 ° C. 87 g (0.473 mole) of cyanuric chloride and 70 g (0.87 mole) of 50 wt% NaOH were added thereto.

At this time, while maintaining the pH to 9.5, the temperature is maintained at 50 ℃.

After both cyanuric chloride and NaOH were added, the mixture was stirred at 50 ° C. for 1 hour 30 minutes.

After cooling the reaction solution to room temperature, concentrated HCl was added to acidify to pH 6. At this time, Na3T-H ₃ was quantitatively precipitated, and the precipitate was filtered by centrifugation to remove a small amount of NaCl which may be buried in the precipitate using a small amount of water.

The solid obtained by centrifugation weighed 136.9 g and contained 60 wt% of Na ₃ T-H ₃ (corresponding to 98 mol% of the total amount of cyanuric chloride added as starting material), with the remainder being water.

136.9 g of the solid obtained by centrifugation was added to 200 ml of water and the temperature was raised to 50 ° C while stirring. 115 g of a 50 wt% NaOH aqueous solution was slowly added while maintaining the temperature of the solution at 50 ° C. to adjust the pH of the solution to 12.5 and stirred for 30 minutes. The mixture was evaporated under reduced pressure to remove 100 ml of water, cooled to 10 ° C. and the mixture was centrifuged to yield 141.46 g of filter cake, which contained 57.4% Na ₃ T-Na ₃ .

The filtrate was crystallized by combining with an aqueous Na ₃ T—Na ₃ solution generated in the next reaction.

The product obtained in Example 1 was Na ₃ T-Na _{3 ·} 3H ₂ O, the moisture-containing crystals were dried in air to obtain a final product.

Example  2

19.04 g Na ₂ S (0.244 mol) and 60.8 g NaSH (1.084 mol) are added to a vessel containing 150 ml water, followed by 80 g cyanuric chloride (0.434 mol). At this time, the temperature was maintained at 45 ℃.

The initial pH was 9 and 50 wt% NaOH was added during the addition of cyanuric chloride and stirred for 1 hour 30 minutes while maintaining this value.

After cooling the reaction solution to room temperature, concentrated HCl was added to acidify to pH 6. At this time, Na3T-H ₃ was quantitatively precipitated, and the precipitate was filtered by centrifugation to remove a small amount of NaCl which may be buried in the precipitate using a small amount of water.

The weight of the solid obtained by centrifugation was 130 g and contained 58 wt% of Na ₃ T-H ₃ (corresponding to 98 mol% of the total amount of cyanuric chloride added as starting material), with the remainder being water.

130 g of the solid obtained by centrifugation was put in 180 ml of water and the temperature was raised to 50 ° C while stirring. 105 g of a 50 wt% NaOH aqueous solution was slowly added while maintaining the temperature of the solution at 50 ° C. to adjust the pH of the solution to 12.5 and stirred for 30 minutes. The mixture was evaporated under reduced pressure to remove 90 ml of water, cooled to 10 ° C. and the mixture was centrifuged to yield 128.07 g of filter cake, which contained 58% Na ₃ T-Na ₃ .

The filtrate was crystallized by combining with Na3T-Na ₃ solution produced in the next reaction.

The product obtained in Example 2 was Na ₃ T-Na _{3 ·} 3H ₂ O, the water-containing crystals were dried in air to obtain a final product.

As described above, the preparation method of the 2,4,6-trimercapto-s-triazine alkali metal salt according to the present invention is simplified by shortening the existing process, minimizing the NaCl content as a reaction by-product, and improving the yield. .

Claims (8)

(a) Cyanuric chloride (2,4,6-trichloro-s-triazine) is mixed with Na ₂ S, NaSH or Na ₂ S and NaSH in a water-soluble medium at a temperature range of 20 to 70 ° C. and pH Reacting at 8.5 to 10.5; (b) acidifying by immediately adding an inorganic acid to the reaction product of step (a) to precipitate 2,4,6-trimercapto-s-triazine (Na ₃ T-H ₃ ); (c) separating the precipitated 2,4,6-trimercapto-s-triazine and dispersing it in an aqueous medium, and then adding an alkali metal hydroxide to alkali the 2,4,6-trimercapto-s-triazine. Obtaining a metal salt; And (d) evaporating and cooling an aqueous alkali metal salt solution of 2,4,6-trimercapto-s-triazine as a result of step (c) to obtain crystallized 2,4,6-trimercapto-s-triazine. A method for producing an alkali metal salt of 2,4,6-trimercapto-s-triazine, comprising the steps of obtaining an alkali metal salt and separating it. delete The method of claim 1, wherein the acidification to pH 1 to 6 by adding an inorganic acid in the step (b). The method of claim 1, wherein in step (b), the inorganic acid is selected from the group consisting of HCl, H ₂ SO ₄ , H ₃ PO ₄ and HNO ₃ . The method of claim 1, wherein the alkali metal hydroxide of step (c) is NaOH or KOH aqueous solution. According to claim 1, wherein the alkali metal hydroxide in the step (c) is a content such that the number of moles of Na contained in the Na ₂ S, NaSH or a mixture of Na ₂ S and NaSH used in the step (a) The method characterized in that the addition. The method of claim 1, wherein the alkali metal hydroxide is added in step (c) to maintain the pH of 11 to 13. The method of claim 1, wherein in the step (d), the 2,4,6-trimercapto-s-triazine alkali metal salt aqueous solution is evaporated under reduced pressure, and then cooled to 0 to 20 ° C.