JPH07188153A - Decoloration of aqueous solution of alkali metal aminoethane sulfonate or alkali metal n-substituted amino ethanesulfonate - Google Patents

Abstract

PURPOSE:To provide a decoloration process giving a colorless and clear aqueous solution of taurine alkali metal salt of high degree of purification from which the contaminants such as alkali metal chlorides as by-products are removed and by which decoloration of the solution can be attained through simplified process. CONSTITUTION:A discolored aqueous solution of an unsaturated or saturated alkali metal aminoethanesulfonate or an alkyl-N-substituted aminoethanesulfonate containing alkali metal chloride is brought into contact with a chelate resin to remove metal ions dissolving in the solution such as iron by adsorption to effect decoloration of solution and the removal of chloride salts as contaminants simultaneously. At this time, the decolored solution is concentration by evaporating water under reduced pressure so that the boiling point of the solution to be condensed may not exceed 110 deg.C to prevent the alkali metal aminoethanesulfonate or an alkyl-N-substituted aminoethane- sulfonate from deterioration and coloration. The alkali aminoethanesulfonate crystallized out is separated by a separation process such as filtration.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for decolorizing an aqueous solution of an alkali metal salt of aminoethanesulfonic acid or an aqueous solution of an alkyl N-substituted aminoethanesulfonic acid alkali metal salt.

The aqueous solution of the alkali metal salt of aminoethanesulfonic acid or the aqueous solution of the alkyl metal of N-substituted aminoethanesulfonic acid is, for example, a β-chloroethanesulfonic acid alkali metal salt (hereinafter referred to as CES-
Write M. However, after reacting M = alkali metal) with an excessive amount of ammonia or alkyl N-substituted amines (hereinafter, these are collectively referred to as amines),
Obtained by adding an alkali metal hydroxide.

In the above aminoethanesulfonic acid alkali metal salt, the sodium aminoethanesulfonic acid whose alkali metal is sodium is reacted with 1,2-epoxyalkane to obtain a dihydroxyalkyl N-substituted sodium aminoethanesulfonic acid. But this compound is a penetrant,
It is used as an emulsion stabilizer, an antistatic agent, a pigment dispersant, and the like, and is also a biochemically useful compound, and is used as a buffer.

Further, aminoethanesulfonic acid obtained by acting a mineral acid such as hydrochloric acid on the above aminoethanesulfonic acid alkali metal salt is a drug substance commonly referred to as "taurine", which is present in the human body and contains cholesterol. It is said to be an essential amino acid for lowering the blood pressure, preventing high blood pressure, or for the growth of newborns, and is contained in a large amount in early breast milk.

In the above-mentioned alkali metal alkyl N-substituted aminoethane sulfonate, potassium methyl aminoethane sulfonate in which the alkyl N-substituted amine is methylamine and the alkali metal is potassium is hydrocarbons. It is used as an absorbent for the removal of carbon dioxide gas and hydrogen sulfide, etc. contained in cracking gas, and is obtained by reacting sodium methylaminoethane sulfonate, whose alkali metal is sodium, with fatty acid or fatty acid chloride. Acylated methylaminoethane sulfonic acid soda is a surfactant that has been known for a long time under the name of "Igepon", has hard water resistance, is easily biodegradable, and is excellent in human body and excellent cleaning. Known as a drug.

[0006]

2. Description of the Related Art Synthesis of aminoethanesulfonic acid alkali metal salt or alkyl N-substituted aminoethanesulfonic acid alkali metal salt from CES-M (hereinafter, these are collectively referred to as taurine alkali metal salts) is synthesized. In Japanese Patent Application No. 5-119804 by the present inventors, a solution obtained by absorbing a large excess of amines in a CES-M aqueous solution is heated according to the following chemical formula 1 and reacted under pressure. , As a salt of the corresponding amines.

[0007]

[Chemical 1]

An alkali metal hydroxide is added to the taurine alkali metal salt as shown in the following chemical formula 2, and the amines are discharged by distillation, whereby the by-produced alkali metal chloride-containing taurine alkali metal salt is added. Obtained as an aqueous solution.

[0009]

[Chemical 2]

Generally, these taurine alkali metal salts exhibit an alkalinity of pH = 10 to 11, have extremely high solubility in water, and dissolve in water at any ratio.
It is very difficult to take out as a solid matter, and the viscosity of the aqueous solution also increases as the concentration increases, so impurities such as by-produced alkali metal chlorides are usually removed.
Is commercially available and used as a viscous liquid having a viscosity at room temperature of about 4.5 to 8.5 centipoise, and rarely as an aqueous solution of about 65% and a viscosity at room temperature of 300 to 500 centipoise.

The purification method for removing impurities such as by-products such as alkali metal chlorides is described in Japanese Patent Application No. 5-198295 by the present inventor.
According to Japanese Patent Publication No. 5-241350, the basic principle is to evaporate and concentrate water to increase the concentration of taurine alkali metal salts, and to crystallize by-produced alkali metal chlorides by its salting out action to give a solid-liquid solution. This is to obtain an aqueous solution of taurine alkali metal salts from which these contaminants have been removed as a separation liquid.To further remove the by-produced alkali metal chloride, the separation liquid is contacted with an ion-adsorbing resin. It is a waste.

However, the thus obtained aqueous solution of an alkali metal salt of taurine is colored yellow or yellowish brown, and the conventionally known method for decolorizing this coloring solution was the method shown below. .

(1) Activated carbon method (JP-A-3-188057)
(2) Hydrogen reduction method in the presence of a metal catalyst (JP-A-3-
No. 261756) Of these methods, (1) is simple in equipment and operation because the aqueous solution is simply brought into contact with powdery or granular activated carbon, but the decolorizing effect is a by-product alkali. It is limited to the case of an aqueous solution of taurine alkali metal salts in which a large amount of metal chlorides and other contaminants are not removed, and cannot be decolorized with an unsaturated taurine alkali metal salt solution in which the by-product alkali metal chlorides are removed. Have been described.

Further, according to the experiments conducted by the present inventor, even if an aqueous solution of an alkali metal salt of taurine containing undiluted contaminants such as by-product alkali metal chloride is contained in an unsaturated aqueous solution having a low dissolved substance concentration, , Although it has some decolorizing effect,
It was not sufficiently decolorized. That is, the decolorizing effect of an aqueous solution of an alkali metal salt of taurine by activated carbon is limited to the case where the aqueous solution is a saturated aqueous solution in which a large amount of impurities such as an alkali metal chloride exists in a high concentration or an unsaturated aqueous solution which is close to saturation .

A further major drawback thereof is that after decolorizing an aqueous solution in which a large amount of alkali metal chloride coexists, impurities are removed from the aqueous solution and the aqueous solution is heated under atmospheric pressure. The separated liquid, which is concentrated and crystallized by crystallization of the by-product alkali metal chloride, is again colored.

Therefore, when the method is used, it is impossible to obtain a colorless and transparent aqueous solution of an alkali metal salt of taurine from which contaminants such as by-product alkali metal chloride are removed.

On the other hand, the method (2) is a method capable of decolorizing regardless of the presence of contaminants such as by-product alkali metal chlorides, but for a few minutes, hydrogen, which has a high risk of ignition and explosion, is injected. ,
It undergoes a reduction reaction under pressure and heating in the presence of a metal catalyst such as Raney nickel, and has the drawback that the equipment and operation become complicated.

[0018]

The object of the present invention is to obtain CE.
S-M, amines, an aqueous solution of an alkali metal salt of taurine obtained from an alkali metal hydroxide, regardless of whether or not a large amount of impurities such as an alkali metal chloride coexist, and the aqueous solution is saturated, To provide a method for producing a colorless and transparent aqueous solution of an alkali metal salt of taurine, which is decolorized by a simple method regardless of being unsaturated and is free from contaminants such as a by-product alkali metal chloride. is there.

[0019]

The present inventor has made diligent efforts to investigate the cause of coloring such an aqueous solution of an alkali metal salt of taurine, and as a result, the main cause thereof is the presence of metal ions such as iron. The cause is that the aqueous solution is deteriorated of the taurine alkali metal salt by being exposed to a high temperature of 110 ° C. or higher.

Therefore, the specific decolorizing method according to the technique of the present invention is to decolorize by contacting an aqueous solution of an alkali metal salt of taurine with a chelating resin to adsorb and remove metal ions such as iron, and by-product alkali metal chloride. In the step of removing impurities such as impurities by crystallization, the aqueous solution is concentrated under reduced pressure so that the boiling point of the aqueous solution is 110 ° C. or lower, preferably 60 to 90 ° C. This is to prevent new coloring due to deterioration of salts.

The details of the technique of the present invention will be described below.

The taurine alkali metal salt aqueous solution synthesized from CES-M contains a slight amount of metal ions such as iron but is colored. This is considered to be derived from the raw material CES-M.

When CES-M is dissolved in an aqueous medium, it can be stored under heating or at room temperature for a long time.
It has the property of being hydrolyzed and showing acidity at pH = 1.5 to 3.0.

For this reason, it is inevitable that the CES-M manufactured by the equipment made of a normal corrosion-resistant metal material is a product containing some metal ions such as iron although it is a trace amount. On the other hand, metal ions such as iron form hydroxides in neutral or alkaline aqueous solutions and become insoluble.
Usually, it is removed by an operation such as filtration, but in an aqueous solution of an alkali metal salt of taurine, these metal ions exist in excess of their solubility and do not precipitate. It is considered that this is due to the chelating action due to the fact that the taurine alkali metal salts are aminosulfonic acids.

Therefore, in the technique of the present invention, decoloring is carried out by contacting an aqueous solution of an alkali metal salt of taurine with a chelate resin to adsorb and remove metal ions such as iron that are contaminated.

The decolorization process using this chelate resin
By contacting an unsaturated taurine alkali metal salt aqueous solution containing a by-product alkali metal chloride, which is synthesized from S-M, amines and alkali metal hydroxides, and which has discharged excess amines, with a chelate resin Alternatively, the unsaturated aqueous solution may be partially concentrated, and a saturated aqueous solution of alkali metal taurine containing a by-product alkali metal chloride may be brought into contact with the chelate resin. Further, an aqueous solution of an alkali metal salt of taurine from which a by-product alkali metal chloride is removed may be brought into contact with a chelating resin. However, in an aqueous solution having an alkali metal salt concentration of taurine of about 50% or more, it is heated or water is used. It cannot be decolorized unless it is diluted and the viscosity of the aqueous solution is less than about 20 centipoise. It is considered that this is because when the concentration of the alkali metal salt of taurine increases, the viscosity of the aqueous solution also increases and the diffusion becomes insufficient.

Further, as to the deterioration and coloring due to high temperature, which is another cause of coloring the taurine alkali metal salts, according to US Pat. No. 2,880,219, taurine sodium salt is represented by the following chemical formula 3 at high temperature. It is described that ammonia is released and ditaurate and tritaurate are by-produced, as shown in FIG.

[0028]

[Chemical 3]

Further, the above-mentioned Japanese Patent Application Laid-Open No. 3-2 which is a hydrogen decolorization method.
According to No. 61765, it is described that methyl taurine sodium salt emits an amine odor at a high temperature of 120 ° C. or higher and does not decolor even under hydrogen pressure. American Che
m. Abstr. 61 5,245h (1964), even lower, 70 ~
It is described that even if the temperature is 80 ° C., it will be oxidized when forcedly blowing air into the methyltaurine potassium salt aqueous solution.

On the other hand, in the method for producing an aqueous solution of an alkali metal salt of taurine, the synthetic steps thereof are as described in Japanese Patent Application No. 5-119804 by the present inventors.
Even if the reaction temperature is 100 ° C. or lower, it is an extremely fast reaction that can be completed in a residence time of 20 minutes or less, and amines that have a high risk of ignition and explosion are used. Since it is performed in an atmosphere without oxygen such as replacing the atmosphere with nitrogen gas, it is not colored, but after the amines are discharged, by concentration, in the step of crystallizing the by-produced alkali metal chloride, When the by-produced alkali metal chloride is highly crystallized to remove it, the concentration of taurine alkali metal salt becomes 60 to 70%, and at atmospheric pressure, the boiling point of the concentrated solution is excellent because of the boiling point raising effect of the melt. It exceeds 110 ℃ and reaches over 120 ℃.

That is, the present inventors have found that in this step, the taurine alkali metal salt is thermally deteriorated and the aqueous solution thereof is newly colored.

Therefore, in the technique of the present invention, the boiling point of the aqueous solution is 110 ° C. or less, preferably 60 to 90 ° C., more preferably, by performing the crystallization step by concentrating the by-produced alkali metal chloride under reduced pressure. By performing the treatment at about 80 ° C., the thermal deterioration of the taurine alkali metal salt and the coloration due to the thermal deterioration are prevented. In the case of the technology of the present invention, by combining these two technologies, A colorless and transparent aqueous solution of an alkali metal salt of taurine from which impurities such as by-product alkali metal chlorides are highly removed is produced.

[0033]

According to the present invention, coloring due to metal ions such as iron is decolorized by bringing the aqueous solution into contact with a chelate resin, and coloring due to thermal deterioration of taurine alkali metal salts is
In the crystallization step by concentrating the by-produced alkali metal chloride, the boiling point of the aqueous solution is preferably 6 ° C or less so that the boiling point does not exceed 110 ° C.
0 to 90 ° C, more preferably about 80 ° C,
It is prevented by performing under reduced pressure.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[0035]

【Example】

Example 1 CES-Na = 99.99% by weight, common salt = 0.11% by weight, sodium 1,2-ethanedisulfonate = 0.26% by weight, mirabilite = trace Powder CES-Na having analytical values
Was dissolved in water, and an aqueous solution containing CES-Na = 20.28% by weight was placed in a stainless steel autoclave, and after replacing the atmosphere with nitrogen gas, the aspirator was set to about -750 mmHg, and then 14 times the chemical of CES-Na. An equivalent amount of methylamine was introduced, absorbed, and reacted at 90 ° C. for 17 minutes, and then 48% of a chemical equivalent to the raw material CES-Na and a caustic soda aqueous solution were added, and excess methylamine was distilled off by distillation. Taurine sodium salt = 16.93% by weight,
Salt = 6.43% by weight, methyl ditaurate = 0.63
% By weight, iron ion = 1.50 ppm, Glauber's salt = trace, pH
An aqueous solution of = 11.5 was obtained. 2897.0 g of this aqueous solution
25% hydrochloric acid (about 2 drops) was added thereto to adjust the pH to 11.0, and the aqueous solution was colored with APHA chromaticity = 60.

This pH-adjusted aqueous solution was poured into a glass cylinder filled with 80 ml of IRC-718, a chelating resin manufactured by Organo Co., in a wet state for about 9 hours, and then poured into a glass cylinder 289.
3.5 g of flowing liquid was obtained.

This flowing liquid contained 16.72% by weight of sodium methyl taurine salt, and had iron ions <0.01 ppm.
It was a colorless transparent liquid with APHA chromaticity = 10.

2876.8 g of this decolorizing solution was placed in a 3 liter separable flask, the flask was immersed in an oil bath, and the atmosphere was replaced with nitrogen gas.
The water was evaporated under reduced pressure so as not to exceed 5 ° C. and concentrated.

At the time when the amount of evaporated water reached about 1425 ml, a crystallized substance was found in the concentrated liquid and became cloudy, but the concentration was continued until the total amount of evaporated water reached 1940 ml. The pressure at this time is about 170 mmHg in absolute pressure.
And the slurry liquid temperature was 83.7 ° C.

The slurry liquid was put into a centrifugal filter machine which was warmed by circulating hot water of 75 to 85 ° C. in advance in its jacket portion to separate solid matters, and filtrate = 713.2 g.
Got

This filtrate contains methyltaurine sodium salt = 65.51% by weight, methylditaurate = 2.44% by weight, sodium 1,2-ethanedisulfonic acid = 0.19% by weight, salt = 0.64% by weight. , Iron ion <0.01ppm, which was slightly yellowish when observed through white filter paper, but it was a colorless transparent liquid with APHA chromaticity = 20. Methyl ditaurate / methyl taurine sodium Salt (wt / wt) = 0.037, and its quantitative ratio was the same as before the experiment.

This filtrate has a viscosity of 250 when cooled to room temperature.
Since it was a centipoise viscous liquid, this filtrate 697.
Ion-exchanged water (505.0 g) was added to 5 g, and the total amount was 120
2.5 g of methyl taurine sodium salt = 38.
The 00 wt% diluted solution had an APHA chromaticity of 10, and was a completely colorless and transparent liquid even when placed on a white filter paper and viewed through a watermark, and its viscosity at room temperature was about 7.0 centipoise. It was

Example 2 Manufactured from 1,2 ethane dichloride and sodium sulfite, CES-Na = 15.35% by weight, salt = 7.04
Unpurified C having a composition of wt%, 1,2 ethanedisulfonic acid sodium = 2.00 wt%, Glauber's salt = 1.30 wt%
Methyltaurine sodium salt = 13.59 in the same manner as in Example 1 using an aqueous solution of ES-Na, an aqueous solution of 18% chemical equivalent of CES-Na, and an aqueous solution of 48% caustic soda having chemical equivalent of CES-Na. % By weight, salt = 1
1.52% by weight, methyl ditaurate = 0.14% by weight, sodium 1,2-ethanedisulfonate = 1.85% by weight, mirabilite = 1.20% by weight, iron ion = 8.52 ppm,
An aqueous solution with APHA chromaticity = 100 was synthesized.

To 2900.7 g of this aqueous solution was added 1% of 98% sulfuric acid.
After 7.0 g was added dropwise and the pH was adjusted to 10.2, the water was evaporated under reduced pressure and concentrated so that the boiling point of the aqueous solution did not exceed 80 ° C. as in Example 1.

When the amount of evaporated water reached about 800 ml, the concentrated liquid became cloudy due to crystallized substances, so the concentration was stopped, the concentrated liquid was cooled to 15 ° C., and unpurified CES-Na was used to confine it. Sodium 1,2-ethanedisulfonic acid was crystallized and removed by filtration to obtain a separated filtrate 19
67.1 g was obtained. The filtrate contained 8.13 pp iron ions.
The coloring liquid contained m and had an APHA chromaticity of 90.

1950.0 g of this separated filtrate was poured into the same chelate resin tower used in Example 1 over about 8 hours,
1948.2 g of flowing liquid was obtained. This circulating liquid is methyl taurine sodium salt = 19.80%, iron ion <0.0.
It was a colorless transparent liquid with 1 ppm and APHA chromaticity = 10.

1934.5 g of this decolorizing solution was transferred to a 2 liter separable flask, and salt and mirabilite were removed in the same manner as in Example 1. Since these inorganic salts are much more than those in Example 1, the operation was performed in two steps.

In the first time, about 610 ml of water was evaporated under reduced pressure so that the boiling point of the decolorizing liquid did not exceed 80 ° C., and the slurry liquid in which salt and mirabilite were crystallized was heated in the same manner as in Example 1. Applied to the centrifugal filter, solid-liquid separated, 114
5.6 g of filtrate was obtained. The filter cake was washed with 44.5 g of ion-exchanged water to wash the attached portion, and the wash cake 167.
1 g and 42.7 g of water recovered by washing were obtained. This washed and recovered water was mixed with the above filtrate, and the second operation was performed.

In the second time, as in the first time, about 465 ml of water was evaporated under reduced pressure so that the temperature did not exceed 80 ° C., and the crystallized inorganic salts were separated by a warm centrifugal filter, and 551.9 g of filtrate. Got

The composition of this filtrate was as follows: sodium methyltaurine salt = 66.98% by weight, salt = 0.54% by weight, Glauber's salt = 0.05% by weight, methylditaurate = 0.72% by weight, 1,2-ethane. Sodium disulfonate = 1.04% by weight, iron ion <0.01 ppm, APHA chromaticity = 20, and an aqueous solution showing viscosity when cooled.

405.1 g of ion-exchanged water was added to 535.2 g of this filtrate to dilute it, and an aqueous solution containing methyl taurine sodium salt = 38.00 wt% was prepared by Organo Corporation.
The strong basic anion adsorption resin IRA-400 was poured into a glass cylinder filled with 115 ml in a wet state for 3 hours, and 22.3 g of a 35% caustic soda aqueous solution was added to the flowing liquid.
Was added dropwise, and the aqueous solution adjusted to PH = 11.0 was 954.
5 g, methyl taurine sodium salt = 36.13% by weight, methyl ditaurate = 0.39% by weight, 1,2 ethanedisulfonic acid sodium salt, salt, mirabilite trace amount, AP
It is a highly purified colorless transparent liquid with HA chromaticity = 10,
Methyl ditaurate / methyl taurine sodium salt (wt /
wt) was about 0.011, which was almost unchanged from before the experiment.

Example 3 One drop of 25% hydrochloric acid was added dropwise to 2897.7 g of an aqueous methyl taurine sodium salt solution having the same composition as that used in Example 1,
Adjust the pH to 11.1 and put this pH adjustment solution in a 3 liter separable flask, immerse the flask in an oil bath, and evaporate water under reduced pressure in the atmosphere so that its boiling point does not exceed 80 ° C. And concentrated. When the amount of evaporated water collected in the trap reached about 1415 ml, the concentrated liquid became cloudy due to crystallized substances, but the concentration continued, and when the total amount of evaporated water reached about 1965 ml, the concentration was stopped and the crystallization started. As in the case of Example 1 and Example 2, the product was subjected to solid-liquid separation with a heated centrifugal filter to obtain 726.9 g of a filtrate.

This filtrate is methyl taurine sodium salt =
It was a colored aqueous solution containing 65.66% by weight, iron ions = 5.35 ppm, and APHA chromaticity = 80.

To 709.3 g of this filtrate was added ion-exchanged water 51.
6.2 g was added, and methyl taurine sodium salt = 38.
An amount of a flowing solution of the aqueous solution diluted to 00% was applied to the chelate resin-filled cylinders used in Examples 1 and 2 over about 5 hours to obtain 1232.4 g. Methyltaurine sodium salt = 37.32% by weight, methyl Ditaurate = 1.37% by weight, 1,2-ethanedisulfonic acid sodium salt = 0.12% by weight, salt = 0.83% by weight, Glauber's salt = 0.10% by weight, iron ion <0.01% by weight, APHA It was a colorless transparent liquid with a chromaticity of 10.

Comparative Example 1 Two drops of 25% hydrochloric acid were added dropwise to 2896.0 g of an aqueous methyltaurine sodium salt solution having the same composition as those used in Examples 1 and 3, and the pH was adjusted to 10.9. The liquid was washed with 45.5 g of granular coconut husk activated carbon and poured into a column filled with a glass cylinder having an apparent volume of 100 ml for about 10 hours to obtain a flow liquid of 2891.8 g.

This circulating liquid was a methyl taurine sodium salt = 16.74%, contained iron ions = 0.05 ppm, and was a slightly yellowish colored liquid with APHA chromaticity = 20-30.

2874.4 g of this aqueous solution was added to the atmosphere,
The water was evaporated and concentrated under atmospheric pressure. Evaporated water volume is about 1
At 430 ml, it began to turn cloudy due to crystallized substances, but the concentration was continued, and about 1960 ml of water was evaporated,
Although the concentration was stopped, the temperature of the concentrate finally reached 128.6 ° C. The crystallized product was subjected to solid-liquid separation by a heated centrifugal filter in the same manner as in the case of Example, and a separated filtrate = 710.5 g was obtained.

This filtrate is methyl taurine sodium salt =
64.56%, methyl ditaurate = 3.55%, iron ion = 0.20 ppm, APHA chromaticity = 60, and a colored aqueous solution which became viscous when cooled. Also,
Methyl ditaurate / methyl taurine sodium salt (wt /
wt) = 0.55, which is larger than the same value before the experiment = 0.037, and deterioration of methyl taurine sodium salt due to heat was expected.

Next, 485.8 g of ion-exchanged water was added to 695.0 g of this filtrate, and the concentration of the sodium methyl taurine salt solution was diluted to 38.00% by weight to prepare an aqueous solution of 0.12.
It was a colored aqueous solution containing ppm iron ions and APHA = 40.

Further, this diluted solution was flown into a column newly packed with the same chelating resin as used in Example 1,
Iron ion <0.01ppm, but the circulating fluid APHA
Although the chromaticity was reduced to 30, it was still colored and a colorless transparent liquid could not be obtained.

[0061]

As is apparent from the above description, when the technique of the present invention is used, it is decolorized by a simple method, impurities such as by-produced alkali metal chlorides are removed, and highly purified, colorless. A transparent aqueous solution of an alkali metal salt of taurine can be produced.

Claims (5)

[Claims] 1. Dissolved iron by contacting a colored aqueous solution of an unsaturated or saturated aminoethanesulfonic acid alkali metal salt containing an alkali metal chloride or an alkyl N-substituted aminoethanesulfonic acid alkali metal salt with a chelate resin. Adsorbs and removes metal ions such as to decolorize,
In the process of removing coexisting by-produced alkali metal chlorides, the decolorizing solution is concentrated by evaporating water under reduced pressure so that the boiling point does not exceed 110 ° C., thereby lowering the boiling point of the concentrated solution. Aminoethane characterized by preventing deterioration and coloration of an aminoethanesulfonic acid alkali metal salt or an alkyl N-substituted aminoethanesulfonic acid alkali metal salt, and removing a crystallized by-produced alkali metal chloride by a separation method such as filtration. A method for decolorizing an aqueous solution of an alkali metal sulfonate or an aqueous solution of an alkyl N-substituted aminoethanesulfonic acid alkali metal salt. 2. In the method for decolorizing an aqueous solution of an alkali metal salt of aminoethanesulfonic acid or an aqueous solution of an alkali metal salt of alkyl N-substituted aminoethanesulfonic acid according to claim 1, first, under a reduced pressure so that the boiling point does not exceed 110 ° C. By evaporating water to condense it with water and lowering the boiling point of the concentrate, deterioration and coloring of the aminoethanesulfonic acid alkali metal salt or alkyl N-substituted aminoethanesulfonic acid alkali metal salt are prevented, and a by-product crystallized. An aqueous solution of an unsaturated or saturated alkyl N-substituted aminoethanesulfonic acid alkali metal salt excluding the alkali metal chloride is then added.
A method of decolorizing an aqueous solution of an alkali metal salt of aminoethanesulfonic acid or an aqueous solution of an alkyl N-substituted aminoethanesulfonic acid alkali metal salt, which comprises contacting with a chelate resin and adsorbing and removing metal ions such as iron. 3. The method for decolorizing an aqueous solution of an alkali metal aminoethanesulfonate or an aqueous solution of an alkyl N-substituted aminoethanesulfonic acid alkali metal according to claim 1, wherein the alkaline metal salt of aminoethanesulfonic acid or the alkyl N-substituted amino is used. Ethanesulfonic acid alkali metal salt is β
-Aminoethanesulfonic acid alkali metal salt aqueous solution or alkyl N-substituted aminoethanesulfonic acid alkali metal salt aqueous solution characterized by being synthesized from chloroethanesulfonic acid alkali metal salt and ammonia or alkyl N-substituted amines and alkali metal salt Decolorization method. 4. A method of decolorizing an aqueous solution of an alkali metal salt of aminoethanesulfonic acid or an aqueous solution of an alkali metal salt of an alkyl N-substituted aminoethanesulfonic acid according to claim 1, wherein the coexisting by-product alkali metal chloride is removed. ,
This decolorizing solution is characterized in that water is evaporated and concentrated under reduced pressure so that its boiling point is in the range of 60 to 90 ° C., and the crystallized by-product alkali metal chloride is removed by a separation method such as filtration. A method for decolorizing an aqueous solution of an alkali metal salt of aminoethanesulfonic acid or an aqueous solution of an alkyl N-substituted aminoethanesulfonic acid alkali metal salt. 5. A method for decolorizing an aqueous solution of an alkali metal salt of aminoethanesulfonic acid or an aqueous solution of an alkyl N-substituted aminoethanesulfonic acid alkali metal salt according to claim 1, wherein a coexisting by-produced alkali metal chloride is removed. ,
Aminoethane characterized in that this decolorizing solution is concentrated under reduced pressure by evaporating water so that its boiling point is around 80 ° C., and crystallized by-product alkali metal chloride is removed by a separation method such as filtration. A method for decolorizing an aqueous solution of an alkali metal sulfonate or an aqueous solution of an alkyl N-substituted aminoethanesulfonic acid alkali metal salt.