JPH1149735A - Treatment of crystallization mother liquor of alanine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating crystallization mother liquor of alanine, by which the crystallization mother liquor of the alanine can be formed into a waste liquid capable of being suitably subjected to a burning treatment without damaging a furnace wall of an incinerator and without generating soot and smoke including air pollutants such as sulfur dioxide and nitrogen oxides. SOLUTION: This method for treating crystallization mother liquor of alanine comprises separating impurities such as an alkali component and others from the crystallization mother liquor of the aniline by an electrodialysis. Preferably, the electrodialysis is carried out by introducing the crystallization mother liquor to a room (b), which is one of the rooms between an anion exchange membrane A and a cation exchange membrane C in an apparatus constituted of basic units comprising a bipolar membrane B, the anion exchange membrane A, the cation exchange membrane C and the bipolar membrane B arranged in order, collecting byproducts from the room (a) between the bipolar membrane B and the anion exchange membrane A as a waste material, and collecting an alkaline component (sodium hydroxide) from a room (c) between the cation exchange membrane C and the bipolar membrane B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for treating alanine waste liquid. More specifically, the alkali component such as sodium hydroxide and the organic by-products to be disposed of as other impurities are separately separated from the crystallization mother liquor of alanine, the alanine and the alkali component are recovered, and the organic by-product is contained. The present invention relates to a method for treating an alanine waste liquid so that the waste liquid (recovered waste liquid) can be incinerated.

[0002]

2. Description of the Related Art Usually, alanine is represented by the following (1) to (5).
Is synthesized according to the steps of (1) Aminopropionitrile is synthesized from lactonitrile and a large excess of ammonia. (2) Add sodium hydroxide to hydrolyze aminopropioniter, synthesize sodium alanine, and simultaneously remove ammonia. (3) Alanine is obtained by removing sodium from alanine sodium by an ion exchange reaction. (4) The reaction solution of the above (3) is concentrated, crystallized and dried to obtain an alanine product. The mother liquor after crystallization here is referred to as a first mother liquor. (5) The first mother liquor is further concentrated and crystallized to obtain alanine crude crystals, which are added to the crystallization of (4) to increase the yield. The mother liquor after crystallization here is referred to as a second mother liquor.

Here, the second mother liquor of the above (5) contains a large amount of impurities, and it is difficult to recover alanine any more.

[0004] In the synthesis reaction of alanine, anionic organic acids such as iminodipropionic acid, lactic acid, acetic acid and formic acid are synthesized as by-products. Therefore, sodium cannot be completely removed in the step (3), and the sodium salt of these organic acids is contained in the waste liquid. If this waste liquid is incinerated, sodium remains in the incinerator, so that the wall of the incinerator is damaged and its life is shortened. In addition, when a mineral acid such as sulfuric acid is added and incinerated as sodium sulfate, etc., the sodium sulfate melted in the furnace accumulates in the low-temperature part near the outlet, blocking the flue, and also causing sulfur dioxide and nitrogen oxides. This is not preferable because soot containing air pollutants is generated. For this reason, incineration is not possible, and a separate waste liquid treatment facility must be provided for the treatment of waste liquid, which must be treated using a large amount of chemicals, etc., and must be discharged after removing environmental pollutants. Become.

Japanese Patent Application Laid-Open No. 57-81443 discloses that a two-chamber method comprising electrolyzing an aqueous solution containing sodium alanine obtained in the above step (2), followed by an anion exchange membrane and a cation exchange membrane. A method for separating alanine from other organic acid salts by dialysis is described. In the method described in the above publication, the crystallization yield of alanine is certainly improved, but sodium remains on the waste liquid side containing salts of other organic acids separated from alanine by electrodialysis. Furthermore, the waste liquid cannot be treated as it is by a simple method.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a crystallization mother liquor of alanine which does not damage the furnace wall of an incinerator and generates soot containing air pollutants such as sulfur dioxide and nitrogen oxides. An object of the present invention is to provide a method for treating a crystallization mother liquor of alanine, which can be used as a waste liquid which can be suitably incinerated without clogging a flue of an incinerator.

Another object of the present invention is to recover a recyclable alkali component such as sodium hydroxide and an alanine component from a crystallization mother liquor of alanine, and to directly use the crystallization mother liquor containing residual by-products as it is. It is an object of the present invention to provide a method for treating a mother liquor of alanine which can be incinerated as waste liquid.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on a method of treating a mother liquor for crystallization of alanine in order to solve the above-mentioned problems. As a result, the inventors have found that a bipolar membrane and an anion / cation exchange membrane can be used in combination. Can be separated into sodium hydroxide (alkali component) and organic acid (acid component) separately without being separated as a salt of the organic acid by electrodialysis, and waste liquid containing by-products of the organic acid to be disposed of The present inventors have found that the waste liquid can be directly incinerated because it does not contain an alkali component such as sodium or an additive such as a mineral acid, thereby completing the present invention.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for treating a mother liquor of alanine according to the present invention is characterized in that an alkali component and other impurities are separately separated from the mother liquor of alanine by electrodialysis.

The mother liquor for alanine crystallization that can be used in the present invention contains the above (4) and (5), which are generated during the process of synthesizing alanine by the above-mentioned steps (1) to (5).
And at least one of the first mother liquor and the second mother liquor, which is the mother liquor after the crystallization. Preferably, the first mother liquor is used in order to omit the crystallization step (5).

The electrodialysis method that can be used in the present invention includes an alkali component such as sodium from a mother liquor of crystallization of alanine and other impurities, that is, iminodipropionic acid and lactic acid which are by-produced in the synthesis reaction of alanine. , Acetic acid, formic acid, and other anionic organic acids are not particularly limited as long as they can be separated separately, not as salts of the organic acids.
To (d), a bipolar membrane and an anion.
Various electrodialysis methods appropriately combined with a cation exchange membrane can be used. Here, the bipolar membrane has a structure in which an anion exchange membrane and a cation exchange membrane are joined, and when subjected to electrodialysis, the anion exchange membrane side of the bipolar membrane is placed on the anode (+) side, The bipolar membrane is used with the cation exchange membrane side as the cathode (-) side.

(A) From a positive electrode (+) side to a negative electrode (-) side, a two-chamber bipolar membrane electrodialysis system having two basic chambers alternately arranged in the order of a bipolar membrane and a cation exchange membrane. In the above, the crystallization mother liquor of alanine is introduced into a chamber formed by the cation exchange membrane side of the bipolar membrane and the cation exchange membrane, and a DC voltage is applied to perform electrodialysis, whereby the alanine crystallization mother liquor is positively charged. The ionic sodium component and alanine component permeate the cation exchange membrane, move to the chamber formed by the anion exchange membrane side of the bipolar membrane and the cation exchange membrane, and are collected as sodium hydroxide and alanine. The recovered sodium hydroxide and alanine are returned to the step (2) and recycled together. Further, the remaining mother liquor obtained by separating and recovering the sodium component and the alanine component from the crystallization mother liquor of alanine is directly incinerated as waste liquid. This dialysis method satisfies the first object of the present invention, ie, the purpose of waste liquid treatment, and is effective. However, after sodium moves preferentially, the conductivity decreases and the recovery rate of alanine is reduced. Lower.

(B) From the anode (+) side to the cathode (-) side, a two-chamber bipolar membrane electrodialysis system having two basic chambers arranged alternately in the order of a bipolar membrane and an anion exchange membrane. In the above, the crystallization mother liquor of alanine is introduced into the chamber formed by the anion exchange membrane side of the bipolar membrane and the anion exchange membrane, and the dialysis is carried out by applying a DC voltage to perform electrodialysis. Anionic organic acid components such as dipropionic acid, lactic acid, acetic acid, and formic acid pass through the anion exchange membrane and move to the chamber formed by the cation exchange membrane side of the bipolar membrane and the anion exchange membrane, and as impurities. Removed. The organic acid by-product as the removed impurities is directly incinerated as waste liquid. The residual mother liquor of alanine containing the sodium component and the alanine component is returned to the above step (2) and recycled together. This dialysis method is also effective and satisfies the first object of the present invention, that is, the purpose of waste liquid treatment, similarly to the above (a), but the alanine component dissociates into ions only under the dialysis conditions described above. As a result, the alanine is recovered after passing through the anion exchange membrane, so that the recovery rate of alanine is low.

(C) From the anode (+) side to the cathode (−) side, a bipolar membrane, a cation exchange membrane, a cation exchange membrane, and a bipolar membrane are arranged in this order in three chambers. In room type bipolar membrane electrodialysis,
Alanine crystallization mother liquor is introduced into the chamber formed by the cation exchange membrane side of the bipolar membrane on the anode (+) side and the cation exchange membrane (preferably, the mother liquor in the system is circulated by a circulation system), and a DC voltage is applied. Flow and perform electrodialysis.

Thus, the cationic sodium component and the alanine component in the mother liquor for alanine crystallization permeate the cation exchange membrane and move to the cation exchange membrane and the chamber formed by the cation exchange membrane (alanine recovery chamber). I do. Further, of the sodium component and the alanine component that have moved to the alanine recovery chamber, the strongly cationic sodium component preferentially permeates the cation exchange membrane and forms on the cation exchange membrane and the anion exchange membrane side of the bipolar membrane. It moves to the chamber (sodium recovery chamber) where it is recovered and is recovered as sodium hydroxide.

This dialysis operation is continued until the sodium moves to the sodium recovery chamber, the conductivity of the chamber in which the mother liquor of alanine is introduced and the conductivity of the alanine recovery chamber are reduced, and the two are separately separated.

Thereafter, the sodium hydroxide separated and recovered in the sodium recovery chamber is returned to the step (2) and recycled. The alanine separated and recovered in the alanine recovery chamber is the first alanine depending on the mother liquor used.
If it is a mother liquor, it can be recycled before the crystallization in the step (4), and if it is the second mother liquor, it can be returned to the state before the crystallization in the step (5) and recycled. On the other hand, the remaining mother liquor obtained by separating and recovering the sodium component and the alanine component from the alanine crystallization mother liquor is directly incinerated as waste liquid.

(D) As a more preferred embodiment, a three-chamber configuration in which a membrane is arranged in the order of a bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a bipolar membrane from the anode (+) side to the cathode (−) side is provided. In a three-chamber bipolar membrane electrodialysis as a basic unit, a mother liquor of alanine is introduced into a chamber (salt chamber) between the anion exchange membrane and the cation exchange membrane (preferably, the mother liquor in the system is circulated by a circulation system). B) electrodialysis by applying a DC voltage.

Thus, the cationic sodium component in the mother liquor for crystallization of alanine permeates through the cation exchange membrane,
It moves to the chamber (sodium recovery chamber) formed by the anion exchange membrane side of the bipolar membrane on the cathode (-) side and the cation exchange membrane, and is recovered as sodium hydroxide. On the other hand, iminodipropionic acid, lactic acid, acetic acid in the crystallization mother liquor of alanine,
Anionic organic acid components such as formic acid permeate through the anion exchange membrane, move to the chamber formed by the anion exchange membrane and the cation exchange membrane side of the bipolar membrane on the anode (+) side, and are removed as impurities. You.

The dialysis operation is continued until the sodium is moved to the sodium recovery chamber and each is separated separately on the basis of a decrease in the conductivity of the chamber into which the mother liquor for alanine has been introduced.

Thereafter, the sodium hydroxide separated and recovered in the sodium recovery chamber is returned to the above step (2) and recycled. Further, the desalted alanine crystallization mother liquor containing the alanine component remaining in the chamber between the anion exchange membrane and the cation exchange membrane may be the first mother liquor depending on the mother liquor used.
If it is a mother liquor, it can be recycled before the crystallization in the step (4), and if it is the second mother liquor, it can be returned to the state before the crystallization in the step (5) and recycled. On the other hand, organic acid by-products separated into a chamber formed by the cation exchange membrane side of the bipolar membrane and the anion exchange membrane and removed as impurities are directly incinerated as waste liquid.

Furthermore, in the electrodialysis method (d), the pH of the crystallization mother liquor of alanine introduced into the chamber (salt chamber) between the anion exchange membrane and the cation exchange membrane is adjusted by adding ammonia to the isoelectricity of alanine. A point around 6.0 (pH 5.5 to 5.5)
By performing the electrodialysis while maintaining the desired effect within the range of 6.5), both the recovery rate of alanine in the salt room and the recovery rate of sodium in the sodium recovery room can be improved. Can be improved. This is because by setting the pH of the crystallization mother liquor near 6.0, which is the isoelectric point of alanine, alanine is less likely to be affected by an electric field.

In any of (a) to (d) exemplified above, the waste liquid containing an organic acid as a by-product is
Although it can be incinerated, if the incinerator is equipped with a boiler, the waste liquid can be more effectively used as fuel. Furthermore, the separation liquid containing the alanine component or the mother liquor for alanine crystallization that has been desalted by electrodialysis can be returned to the step before crystallization because impurities are removed, and the product yield increases. More preferably, by returning to the step (4) before crystallization using the first mother liquor, the crystallization step of (5) can be omitted, and the synthesis step of alanine can be simplified. it can.

The above can be easily achieved only by separating sodium and an organic acid by a bipolar membrane electrodialysis method, preferably by introducing the above-mentioned three-chamber bipolar membrane electrodialysis method (d). The bipolar membrane electrodialysis method that can be used in the present invention is not particularly limited, and should not be limited to the configuration of the basic unit (cell) exemplified above. Known techniques are widely applicable, and can be used by appropriately combining various configurations used for an electrodialysis apparatus and equipment (for example,
Characteristics of each membrane such as material, strength, etc., effective membrane area, thickness, number of cells used (number of cells), cell configuration, electrode material, structure of electrodialysis tank and configuration of various members, etc.
The structure of pipes, liquid transporters, storage tanks, etc. in the recovery system and the configuration of various members, etc., and operating conditions (eg, temperature, pH, concentration, electrode solution, solution of solution in each chamber such as alanine crystallization mother liquor) Current, voltage, etc.) can be determined appropriately.

[0025]

The present invention will be described in more detail with reference to examples. In each of the examples specifically illustrated below, in order to perform electrodialysis by the three-chamber bipolar membrane electrodialysis method described in the above (d), as shown schematically in FIG.
From the anode (+) side to the cathode (-) side, three chambers constituted by arranging a membrane in the order of a bipolar membrane B, an anion exchange membrane A, a cation exchange membrane C, and a bipolar membrane B are defined as a basic unit (cell). A three-chamber bipolar membrane electrodialysis device in which three cells were arranged was used. Further, in a cell having three chambers as a basic unit, the chamber formed by the bipolar membrane B on the anode (+) side and the anion exchange membrane A is defined as an anion recovery chamber a, and the anion exchange membrane A and the cation exchange membrane C The chamber formed is a salt chamber b, a chamber formed by the cation exchange membrane C and the bipolar membrane B on the cathode (-) side is a cation recovery chamber, and an anode (+) and a cathode (-) at both ends are provided. The configuration is such that the electrode chamber e is disposed in the chamber.

Example 1 Alanine 140 g / L Iminodipropionic acid 46 g / L Lactic acid 38 g / L Acetic acid 51 g / L Sodium 12 g / L pH 5.0 Conductivity 20 mS / cm (30 ° C.) As the mother liquor for crystallization of alanine, an aqueous solution having the above composition was used. In the electrodialysis apparatus shown in FIG. 1, a 1N aqueous sodium sulfate solution is used to increase the initial conductivity, an 1N sodium hydroxide solution is used in the cation recovery chamber c, and a 1N sodium hydroxide is used in the electrode chamber e.
An aqueous solution of sodium sulfate was used. A Ti / Pt plate was used for the electrodes (+/-), the aqueous solution (crystallization mother liquor of alanine) was circulated to each salt chamber b at a liquid temperature of 30 ° C., and a DC voltage was applied as a constant voltage of 18 V. The operation of the bipolar membrane electrodialysis apparatus was performed, and the electrodialysis treatment was performed. During operation, since water moves from the salt room b, water was added and controlled so that the amount of liquid in the salt room b was always constant. As a result, the pH of the salt room b decreases over time, and when the electrodialysis is finished when the conductivity of the aqueous solution in the salt room b reaches 1.3 mS / cm, the pH of the aqueous solution in the salt room b becomes 4 .0 has been reached.
At this time, the composition of the aqueous solution in the salt room b is as follows: alanine 120 g / L iminodipropionic acid 5.4 g / L lactic acid 2.1 g / L acetic acid 2.9 g / L sodium 0.3 g / L pH5. 0 The conductivity was 20 mS / cm (30 ° C.), and the recovery of alanine was 86.0%. The acid component removal rate was 88.3% of iminodipropionic acid and 9 of lactic acid.
4.6% and acetic acid 94.2%. The sodium recovery in the cation recovery chamber c was 97.5%.

From this, the sodium component in the mother liquor for alanine crystallization permeates through the cation exchange membrane C and moves to the cation recovery chamber c. On the other hand, iminodipropionic acid, lactic acid, The organic acid component of acetic acid permeated through the anion exchange membrane A, moved to the anion recovery chamber a, and it was confirmed that the alkali component and the organic acid component could be separated separately.

Example 2 A crystallization mother liquor of alanine having the same composition as that used in Example 1 was adjusted to pH 6.0 with 28% aqueous ammonia.
Of the three-chamber bipolar membrane electrodialysis apparatus having the same configuration as that of Example 1 shown in FIG.

In this example, the same operating conditions as in Example 1 were used, except that 28% aqueous ammonia was added so that the pH of the salt room b was always 6.0 during the electrodialysis. The electrodialysis was terminated when the conductivity of the salt chamber b reached 1.3 mS / cm. At this time, the composition of the salt chamber aqueous solution was as follows: alanine 132 g / L iminodipropionic acid 5.2 g / L lactic acid 2.1 g / L acetic acid 2.9 g / L sodium 0.1 g / L Was 94.0%. The removal rate of the acid component was 88.8% of iminodipropionic acid and 9 of lactic acid.
4.6% and acetic acid 94.4%. The sodium recovery in the cation recovery chamber c was 99.2%.

From this, the sodium component in the mother liquor for alanine crystallization permeates through the cation exchange membrane C and moves to the cation recovery chamber c, while the iminodipropionic acid, lactic acid, The organic acid component of acetic acid permeates the anion exchange membrane A and moves to the anion recovery chamber a, where the alkali component and the organic acid component can be separated separately, and the aqueous solution containing the desalted alanine component becomes It was confirmed that it was left in the salt room b.

[0031]

According to the present invention, alkali components (sodium hydroxide) and by-products of organic acids such as iminodipropionic acid, lactic acid and acetic acid can be separately separated from the mother liquor of crystallization of alanine. It can increase the recovery rate of alkali components such as sodium hydroxide and alanine components that can be recycled, can be recycled by returning to the process before crystallization, and can collect and remove by-products of organic acids As waste liquid, without injuring the furnace walls of incinerators, generating soot containing air pollutants such as sulfur dioxide and nitrogen oxides, and without incinerating the flue of incinerators, and incinerating it as it is. Can be disposed of.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a three-chamber bipolar membrane electrodialysis apparatus having a basic unit of three chambers constituted by arranging a bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a bipolar membrane in this order. 3 is a drawing schematically showing an example of a configuration (arrangement) of a chamber formed by the film.

[Explanation of symbols]

+: Anode (plate),-: cathode (plate), B
... Bipolar membrane, A ... Anion exchange membrane,
C: cation exchange membrane, a: anion recovery chamber,
b: salt chamber, c: cation recovery chamber, e: electrode chamber.

Claims (4)

[Claims] 1. A method for treating a crystallization mother liquor of alanine, wherein an alkali component and other impurities are separately separated from the crystallization mother liquor of alanine by electrodialysis. 2. The electrodialysis method comprises, as a basic unit, three chambers arranged in the order of a bipolar membrane, an anion exchange membrane, a cation exchange membrane, and a bipolar membrane, and a chamber between the anion exchange membrane and the cation exchange membrane. Introducing a crystallization mother liquor of alanine, recovering by-products in a chamber between the bipolar membrane and the anion exchange membrane, and recovering an alkali component in a chamber between the cation exchange membrane and the bipolar membrane. Item 6. The method for treating a mother liquor for crystallization of alanine according to Item 1. 3. The electrodialysis is carried out while maintaining the pH of the mother liquor of crystallization of alanine introduced into the chamber between the anion exchange membrane and the cation exchange membrane at around 6.0 by adding ammonia. The method for treating a mother liquor for crystallization of alanine according to claim 1 or 2. 4. The method according to claim 1, wherein in the electrodialysis, alanine is further recovered from a mother liquor of desalinated alanine remaining in a chamber between the anion exchange membrane and the cation exchange membrane. The method for treating a mother liquor for crystallization of alanine according to any one of the above.