CN111233717B - Method for separating useful components in taurine crystallization mother liquor - Google Patents

Abstract

A method for separating useful components from taurine crystallization mother liquor is characterized in that the taurine crystallization mother liquor is used as a raw material, sulfate is removed by a barium chloride precipitation method, effective components are converted into taurine and isethionic acid by hydrochloric acid acidification, the taurine and isethionic acid are further esterified by ethanol to generate an esterified product, the esterified product is transferred to an oil phase, after the oil phase is separated, taurine and isethionic acid are obtained by hydrolysis, finally, the isethionic acid and taurine are sequentially separated by evaporative crystallization and cooling crystallization, and the isethionic acid is subjected to neutralization reaction by sodium hydroxide to obtain sodium isethionate; the method can effectively recover useful components taurine and sodium isethionate in the taurine crystallization mother liquor, and can obviously reduce the environmental pollution possibly caused by the discharge of the taurine production waste liquid; has the advantages of low production cost, high recovery rate and easy industrial amplification.

Description

A method for separating useful components in taurine crystallization mother liquor

technical field

The invention relates to the technical field of chemical separation, in particular to a method for separating useful components in taurine crystallization mother liquor.

Background technique

The chemical name of taurine is 2-aminoethylsulfonic acid, the molecular formula is HO ₃ S-CH ₂ -CH ₂ -NH ₂ , the chemical name is β-aminoethyl sulfonic acid or 2-aminoethyl sulfonic acid, relative to The molecular mass is 125.15. The taurine used in industrial production is a white crystalline powder with a melting point of 328°C, non-toxic, odorless, and slightly sour in taste. Taurine is an active substance that regulates the normal physiological activities of the body. It has anti-inflammatory, analgesic, and maintains body penetration. Pressure balance, regulate cell calcium balance, regulate lipid digestion and absorption, increase cardiac contractility, improve body immunity and other biological functions, taurine can be widely used in medicine, fluorescent whitening agent, food additives, biochemical reagents, moisturizing agents and pH buffers.

In industrial production, the preparation of taurine by the ethylene oxide method is divided into three steps: the first step is the addition reaction of ethylene oxide and sodium sulfite to generate sodium isethionate, but also generates a by-product ethylene di Alcohol, polyethylene glycol; the second step is the ammoniation reaction of sodium isethionate to generate sodium aminoethylsulfonate, this step reaction will also generate by-product aminoethylsulfonate ammonia, in addition to a part of hydroxyethyl sulfonate Sodium ethyl sulfonate is not completely reacted; the third step is that sodium aminoethyl sulfonate and sulfuric acid are acidified to generate aminoethyl sulfonic acid, namely taurine, and sodium sulfate is generated by by-product here.

After the above-mentioned three-step reactions are completed, the taurine finished product is obtained after evaporative crystallization and centrifugal separation, and the crystallization mother liquor is composed of: 13% of taurine, 50% of sodium isethionate, ethylene glycol and polyethylene glycol 4 %, sodium sulfate 2% and a very small amount of ammonia aminoethylsulfonate, of which the useful components are taurine and sodium isethionate, taurine can be sold as a finished product, and sodium isethionate is used for ammonia. It is a raw material for chemical production of taurine. In industrial production, the crystallization mother liquor contains many impurity components and is difficult to reuse. Discharging it as a waste liquid not only wastes resources, but also pollutes the environment.

The above-mentioned components of taurine are all easily soluble in water, and methods such as conventional chemical precipitation, evaporative crystallization, cooling crystallization, membrane separation, and ion exchange are all difficult to isolate the active ingredient from the taurine crystallization mother liquor. Therefore, how to effectively separate taurine The useful components taurine and sodium isethionate in the crystallization mother liquor have become an urgent problem to be solved in the industrial preparation of taurine.

SUMMARY OF THE INVENTION

The technical problem solved by the present invention is to provide a method for separating useful components in the taurine crystallization mother liquor. The method undergoes processes such as precipitation, acidification, esterification, hydrolysis, evaporative crystallization, cooling crystallization and the like, and finally separates taurine and Sodium isethionate, using this method can not only effectively recover the useful components taurine and sodium isethionate in the taurine crystallization mother liquor, but also can significantly reduce the possible environment caused by the discharge of taurine production waste liquid It has the advantages of low production cost, high recovery rate and easy industrial scale-up.

The technical problem solved by the present invention adopts the following technical solutions to realize:

A method for separating useful components in taurine crystallization mother liquor, the concrete steps are as follows:

(1) Precipitation: add barium chloride for removing sulfate to an appropriate amount of taurine crystal mother liquor, stir to fully separate out barium sulfate, filter and separate barium sulfate to obtain a first-grade filtrate;

(2) Acidification: Add concentrated hydrochloric acid to the primary filtrate, heat up to 80 °C and stir to promote the conversion of sodium isethionate into isethionic acid, and at the same time, sodium chloride will be precipitated, and the chloride is separated by filtration. Sodium to obtain secondary filtrate;

(3) Esterification: Add an appropriate amount of ethanol to the secondary filtrate, and continue to stir the reaction at 90 °C. The solution is layered and divided into an aqueous layer and an oil layer. The aqueous layer contains ethanol, ethylene glycol, and polyethylene glycol. and a small amount of sodium chloride and sodium sulfate, after separating the water layer, the oil layer contains esterification products, including taurine and isethionate;

(4) Hydrolysis: add an appropriate amount of water to the oil layer generated in step (3), continue to stir and react at 80 °C to obtain a hydrolyzed product, and promote the conversion of taurine and isethionate into cattle by adding water and stirring. Sulfonic acid and isethionic acid;

(5) Evaporative crystallization: the hydrolyzed product obtained in step (4) is further evaporated and crystallized at a temperature of 95 °C to separate out isethionic acid, and after filtration and separation of isethionic acid, a tertiary filtrate is obtained;

(6) Crystallization by cooling: the tertiary filtrate obtained in step (5) was crystallized by cooling at a temperature of 5°C until taurine was fully separated out, and the solid-phase product was filtered and separated to obtain taurine;

(7) Neutralization of isethionic acid: after dissolving the isethionic acid precipitated in step (5), add sodium hydroxide solution to adjust the pH value to neutrality, and evaporate and crystallize at a temperature of 95 ℃ to obtain hydroxyethylsulfonic acid. Sodium ethylsulfonate solid.

In the present invention, in step (1), the stirring time is 30min.

In the present invention, in step (2), the stirring time is 30min.

In the present invention, in step (3), the amount of ethanol added to the secondary filtrate is 60-100 mL.

In the present invention, in step (3), the reaction time is 30min under the condition of 90°C temperature.

In the present invention, in step (4), the water added to the oil layer is 30-50 mL.

In the present invention, in step (4), the reaction time is 1h under the condition of 80°C temperature.

In the present invention, in step (5), the evaporative crystallization time is 1h under the temperature condition of 95°C.

In the present invention, in step (6), the cooling crystallization time is 2h at a temperature of 5°C.

In the present invention, in step (7), the concentration of sodium hydroxide solution is 1 mol/L.

Beneficial effects:

(1) The present invention uses taurine crystallization mother liquor as raw material, and finally separates useful components taurine and hydroxyl from the taurine crystallization mother liquor through processes such as precipitation, acidification, esterification, hydrolysis, evaporative crystallization, and cooling crystallization. Sodium ethyl sulfonate, using this method not only can effectively recover useful components taurine and sodium isethionate in the taurine crystallization mother liquor, but also can significantly reduce the environmental pollution that may be caused by the discharge of taurine production waste liquid, It has the advantages of low production cost, high recovery rate, and easy industrial scale-up;

(2) The present invention utilizes ethanol esterification to promote taurine and isethionic acid to generate an esterified product, which is transferred to the oil phase, thereby realizing useful components and impurity components (ethylene glycol, polyethylene The high-efficiency separation of alcohol and sodium sulfate) effectively solves the problem that conventional methods are difficult to separate.

Description of drawings

FIG. 1 is a schematic flowchart of this embodiment.

Detailed ways

In order to make the technical means, creative features, achievement goals and effects realized by the present invention easy to understand and clearly, the present invention will be further described below with reference to specific embodiments.

Example 1

A method for separating useful components in taurine crystallization mother liquor, the concrete steps are as follows:

(1) Precipitation: add about 3 g of barium chloride to 100 mL of taurine crystallization mother liquor, stir for 30 min to fully separate out barium sulfate, and filter and separate barium sulfate to obtain a primary filtrate;

(2) Acidification: add 30 mL of concentrated hydrochloric acid to the primary filtrate, heat up to 80 °C and stir for 30 minutes to promote the conversion of sodium isethionate into isethionic acid, and at the same time, sodium chloride will be precipitated, filter Separate sodium chloride to obtain secondary filtrate;

(3) Esterification: Add 60 mL of ethanol to the secondary filtrate, and continue to stir the reaction for 30 minutes at 90°C. The solution is layered, and the water layer contains ethanol, ethylene glycol, polyethylene glycol and a small amount of sodium chloride and Sodium sulfate, after separating the water layer, the oil layer contains esterification products, including taurine and isethionate;

(4) Hydrolysis: add 30 mL of water to the oil layer generated in step (3), continue to stir and react at 80°C for 1 h to obtain a hydrolyzed product, and promote the conversion of taurine and isethionate respectively by adding water and stirring For taurine and isethionic acid;

(5) Evaporative crystallization: the hydrolyzed product obtained in step (4) was further evaporated and crystallized at a temperature of 95 °C for 1 h to precipitate isethionic acid, and after filtration and separation of isethionic acid, a tertiary filtrate was obtained;

(6) Crystallization by cooling: the tertiary filtrate obtained in step (5) was cooled and crystallized at a temperature of 5 °C for 2 hours until the taurine was fully separated, and the solid-phase product was separated by filtration to obtain taurine;

(7) Neutralization of isethionic acid: after dissolving the isethionic acid precipitated in step (5), add 1 mol/L sodium hydroxide solution, adjust the pH value to neutrality, and evaporate and crystallize at a temperature of 95 °C , to obtain sodium isethionate as a solid.

Using 100 mL of taurine crystallization mother liquor as raw material, the results of separation experiments showed that the purity of taurine was 98%, and the yield was 62%; the purity of sodium isethionate was 95%, and the yield was 55%.

Example 2

A method for separating useful components in taurine crystallization mother liquor, the concrete steps are as follows:

(1) Precipitation: add about 3 g of barium chloride to 100 mL of taurine crystallization mother liquor, stir for 30 min to fully separate out barium sulfate, and filter and separate barium sulfate to obtain a primary filtrate;

(2) Acidification: add 30 mL of concentrated hydrochloric acid to the primary filtrate, heat up to 80 °C and stir for 30 minutes to promote the conversion of sodium isethionate into isethionic acid, and at the same time, sodium chloride will be precipitated, filter Separate sodium chloride to obtain secondary filtrate;

(3) Esterification: Add 80 mL of ethanol to the secondary filtrate, and continue to stir the reaction for 30 min at 90°C. The solution is layered, and the aqueous layer contains ethanol, ethylene glycol, polyethylene glycol and a small amount of sodium chloride and Sodium sulfate, after separating the water layer, the oil layer contains esterification products, including taurine and isethionate;

(4) Hydrolysis: add 40 mL of water to the oil layer generated in step (3), continue to stir and react at 80 °C for 1 h to obtain a hydrolyzed product, and promote the conversion of taurine and isethionate respectively by adding water and stirring for taurine and isethionic acid;

(5) Evaporative crystallization: the hydrolyzed product obtained in step (4) was further evaporated and crystallized at a temperature of 95 °C for 1 h to precipitate isethionic acid, and after filtration and separation of isethionic acid, a tertiary filtrate was obtained;

(6) Crystallization by cooling: the tertiary filtrate obtained in step (5) was cooled and crystallized at a temperature of 5 °C for 2 hours until the taurine was fully separated, and the solid-phase product was separated by filtration to obtain taurine;

(7) Neutralization of isethionic acid: after dissolving the isethionic acid precipitated in step (5), add 1 mol/L sodium hydroxide solution, adjust the pH value to neutrality, and evaporate and crystallize at a temperature of 95 °C , to obtain sodium isethionate as a solid.

Using 100 mL of taurine crystal mother liquor as raw material, the results of separation experiments showed that the purity of taurine was 98% and the yield was 81%; the purity of sodium isethionate was 95% and the yield was 68%.

Example 3

A method for separating useful components in taurine crystallization mother liquor, the concrete steps are as follows:

(1) Precipitation: add about 3 g of barium chloride to 100 mL of taurine crystallization mother liquor, stir for 30 min to fully separate out barium sulfate, and filter and separate barium sulfate to obtain a primary filtrate;

(2) Acidification: add 30 mL of concentrated hydrochloric acid to the primary filtrate, heat up to 80 °C and stir for 30 minutes to promote the conversion of sodium isethionate into isethionic acid, and at the same time, sodium chloride will be precipitated, filter Separate sodium chloride to obtain secondary filtrate;

(3) Esterification: Add 100 mL of ethanol to the secondary filtrate, and continue to stir the reaction for 30 minutes at 90°C. The solution is stratified, and the water layer contains ethanol, ethylene glycol, polyethylene glycol and a small amount of sodium chloride and Sodium sulfate, after separating the water layer, the oil layer contains esterification products, including taurine and isethionate;

(4) Hydrolysis: Add 50 mL of water to the oil layer generated in step (3), continue to stir and react at 80 °C for 1 h to obtain a hydrolyzed product, and promote the conversion of taurine and isethionate by adding water and stirring. for taurine and isethionic acid;

(5) Evaporative crystallization: the hydrolyzed product obtained in step (4) was further evaporated and crystallized at a temperature of 95 °C for 1 h to precipitate isethionic acid, and after filtration and separation of isethionic acid, a tertiary filtrate was obtained;

(6) Crystallization by cooling: the tertiary filtrate obtained in step (5) was cooled and crystallized at a temperature of 5 °C for 2 hours until the taurine was fully separated, and the solid-phase product was separated by filtration to obtain taurine;

(7) Neutralization of isethionic acid: after dissolving the isethionic acid precipitated in step (5), add 1 mol/L sodium hydroxide solution, adjust the pH value to neutrality, and evaporate and crystallize at a temperature of 95 °C , to obtain sodium isethionate as a solid.

Using 100 mL of taurine crystal mother liquor as raw material, the results of separation experiments showed that the purity of taurine was 99% and the yield was 90%; the purity of sodium isethionate was 97% and the yield was 82%.

In the above embodiment, the taurine crystallization mother liquor is a taurine production waste liquid, and its main components include: taurine, sodium taurine, sodium isethionate, ethylene glycol, polyethylene glycol and sulfuric acid sodium.

From the results of the separation experiment of the useful components prepared in Examples 1 to 3, it can be seen that the separation effect of Example 3 (by adding 100 mL of ethanol in the esterification step and adding 50 mL of water in the hydrolysis step) is the best. At this time, taurine The acid purity is 99%, and the yield is 90%; the purity of sodium isethionate is 97%, and the yield is 82%. As the amount of ethanol added in the esterification step increases, the esterification product increases, so the amount of water added in the hydrolysis step It should also be increased accordingly. At this time, the yield and purity of taurine and sodium isethionate will also increase; but further increase the amount of ethanol and water, the yield and purity of taurine and sodium isethionate will not improve. Obviously, it will increase the subsequent separation load and production cost.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. It should be understood by those skilled in the art that the present invention is not limited by the above-mentioned embodiments. What is described in the above-mentioned embodiments and the description is only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. a method for separating useful components in the taurine crystallization mother liquor, is characterized in that, concrete steps are as follows: (1) Precipitation: add barium chloride for removing sulfate to an appropriate amount of taurine crystal mother liquor, stir to fully separate out barium sulfate, filter and separate barium sulfate to obtain a first-grade filtrate; (2) Acidification: Add concentrated hydrochloric acid to the primary filtrate, heat up to 80 °C and stir to promote the conversion of sodium isethionate into isethionic acid, and at the same time, sodium chloride will be precipitated, and the chloride is separated by filtration. Sodium to obtain secondary filtrate; (3) Esterification: Add an appropriate amount of ethanol to the secondary filtrate, and continue to stir the reaction at 90 °C. The solution is layered and divided into an aqueous layer and an oil layer. The aqueous layer contains ethanol, ethylene glycol, and polyethylene glycol. and a small amount of sodium chloride and sodium sulfate, after separating the water layer, the oil layer contains esterification products, including taurine and isethionate; (4) Hydrolysis: add an appropriate amount of water to the oil layer generated in step (3), continue to stir and react at a temperature of 80 °C to obtain a hydrolyzed product, and promote the conversion of taurine and isethionate into cattle respectively by adding water and stirring. Sulfonic acid and isethionic acid; (5) Evaporative crystallization: the hydrolyzed product obtained in step (4) is further evaporated and crystallized at a temperature of 95 °C to separate out isethionic acid, and after filtration and separation of isethionic acid, a tertiary filtrate is obtained; (6) Crystallization by cooling: the tertiary filtrate obtained in step (5) was crystallized by cooling at a temperature of 5°C until taurine was fully separated out, and the solid-phase product was filtered and separated to obtain taurine; (7) Neutralization of isethionic acid: after dissolving the isethionic acid precipitated in step (5), add sodium hydroxide solution to adjust the pH value to neutrality, and evaporate and crystallize at a temperature of 95 ℃ to obtain hydroxyethylsulfonic acid. Sodium ethylsulfonate solid. 2 . The method for separating useful components in taurine crystallization mother liquor according to claim 1 , wherein in step (1), the stirring time is 30 min. 3 . 3 . The method for separating useful components in taurine crystallization mother liquor according to claim 1 , wherein, in step (2), the stirring time is 30 min. 4 . 4 . The method for separating useful components in taurine crystallization mother liquor according to claim 1 , wherein in step (3), the amount of ethanol added to the secondary filtrate is 60-100 mL. 5 . 5 . The method for separating useful components in taurine crystallization mother liquor according to claim 1 , wherein, in step (3), the reaction time is 30 min under the temperature condition of 90° C. 6 . The method for separating useful components in taurine crystal mother liquor according to claim 1 , wherein in step (4), the water added to the oil layer is 30-50 mL. 7 . 7 . The method for separating useful components in taurine crystallization mother liquor according to claim 1 , wherein, in step (4), the reaction time is 1 h under the temperature condition of 80° C. 8 . The method for separating useful components in taurine crystallization mother liquor according to claim 1 , wherein, in step (5), the evaporation and crystallization time is 1 h at a temperature of 95° C. 9 . 9 . The method for separating useful components in taurine crystallization mother liquor according to claim 1 , wherein, in step (6), the cooling crystallization time is 2h at a temperature of 5°C. 10 . 10. The method for separating useful components in taurine crystallization mother liquor according to claim 1, wherein, when the separation effect is the best, the ethanol added in the esterification step of step (3) is 100 mL, and step ( 4) The water added in the hydrolysis step is 50 mL.

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