JPS58755B2 - Amino acid production method - Google Patents

Description

Detailed Description of the Invention The present invention provides an aqueous solution containing either aminoacetonitrile or α-aminopropionitrile by heating an aqueous solution of sodium oxide or potassium hydroxide. The aqueous solutions of glycine, α-alanine, and β-alanine salts or potassium salts are ion-exchanged in an electrolytic cell using a cation exchange membrane as a diaphragm. , relates to a method for obtaining an aqueous solution of α-alanine or β-alanine and simultaneously recovering an aqueous sodium hydroxide or potassium hydroxide solution.

One advantageous method for obtaining glycine, α-alanine and β-alanine (hereinafter collectively referred to as amino acids) is to
aminoacetonitrile, (NH2CH2CN
), α-aminopropionitrile (CH3CH(NH2
)CN) and β-aminopropionitrile (NH2CH
2CH2CN) (hereinafter collectively referred to as aminonitrile) is reacted with an equimolar amount of an alkali such as sodium hydroxide in an aqueous solution to obtain an alkaline aqueous solution of amino acids, which is then ion-exchanged to obtain an aqueous amino acid solution. Amino acid crystals are obtained through further steps such as concentration, crystallization, filtration, and drying. Conventionally, the ion exchange methods used at this time mainly include (a) contact with an H+ type cation exchange resin; (a) Neutralization with a mineral acid and removal of the resulting mineral salt by electrodialysis.

However, the ion exchange resin method (a) has the following drawbacks.

(a) To regenerate the used resin, an amount of acid equal to or greater than the ion-exchanged alkali is consumed.

(b) All of the acids and alkalis used are contained in the recycled waste liquid in the form of salts, and their concentrations are relatively low.

Therefore, it is difficult to collect it, and even if it is collected, its utility value is low.

(C) In order to obtain a high yield of amino acids produced by ion exchange, it is necessary to wash the used resin with a large amount of water to elute the adsorbed amino acids before regenerating it.

Therefore, the concentration of the resulting amino acid solution is low.

This makes it necessary to evaporate a large amount of water in the subsequent step of isolating amino acids, increasing the amount of energy consumed in this step.

(d) Even after washing with a large amount of water as described in (c) above, the resin contains not only a small amount of amino acids but also a considerable amount of organic substances contained as impurities in the raw amino acid salt solution. They are desorbed during resin regeneration and are included in the regeneration waste liquid mentioned in section (b).

For this reason, not only the yield of amino acids is reduced, but also the waste liquid has high BOD and COD values and cannot be disposed of without some kind of treatment.

However, since this waste liquid is large in volume and contains salt, it is not easy to dispose of it, nor is it cheap.

(e) Ion exchange operations are complicated and involve many repeated steps, making it difficult to streamline them by making them continuous or automating them.

Furthermore, the resin is severely crushed and consumed due to repeated ion exchange and regeneration, which not only increases operating costs but also often causes operational troubles such as clogging of the resin layer and one-sided flow.

On the other hand, the electrodialysis method (a) has the same drawbacks as the resin method, although the generation mechanism is slightly different.

That is, as follows. (a) for neutralization;
An equivalent amount of acid to the alkali contained in the amino acid salt solution is required.

(b) The acids and alkalis used are aqueous solutions of salts (
Since it is collected as waste liquid (hereinafter referred to as waste liquid), it is difficult to reuse and its value is low.

(C) In the electrodialyzer, the amino acid solution is
Since it flows through the space between the cation exchange membrane and the anion exchange membrane, even if the pH value of the solution changes to either acidic or alkaline side from the isoelectric point of the amino acid, the amino acid remains positive or negative. Depending on whether the charge is positive or negative, it is lost into the waste liquid through one of the ion exchange membranes, reducing the yield.

Near the isoelectric point, the pH value varies greatly depending on the presence of a small amount of acid or alkali, but the amino acid aqueous solution to be desalted usually contains various acidic or alkaline organic substances as impurities. Since the amount is not constant, it is extremely difficult to maintain a pH value such that the amino acids are not charged.

Therefore, careful process control is required to maintain a high yield of amino acids.

(d) Acidic or alkaline substances contained as impurities are more easily ionized than amino acids, and depending on whether the charge is positive or negative, they pass through one of the membranes and move into the waste liquid.

Therefore, since the waste liquid also contains these organic substances, B
The OD value and COD value are high, and the treatment is not easy and expensive, as is the case with the ion exchange resin method.

(e) Since the amino acids used in the present invention have relatively small molecular weights, they permeate membranes and are lost into wastewater by molecular diffusion even at the isoelectric point.

In order to reduce this loss, it is effective to keep the amino acid concentration in the solution low, but this increases the amount of energy consumed in the subsequent concentration step.

There are many other known methods for producing amino acids, but
Even in the above-mentioned method, which is currently considered to be superior in quantity,
As such, it has many drawbacks.

The present inventors have developed a method that takes advantage of the advantages of the conventional method, that is, the ease of the reaction process, and does not have the disadvantages mentioned above, namely: (a) No acid consumption; (b) Use of the method. (1) Eliminating the loss of amino acids; (2) Not generating waste liquid; (1) Preventing dilution of the amino acid solution and reducing concentration. As a result of various studies in order to establish a method that would enable all of the following: (f) continuous operation with easy process control, we found that the process of hydrolyzing aminonitrile with alkali and using electrodes It was discovered that the desired objective could be achieved by combining the process with an ion exchange process, and the present invention was completed.

The present invention is based on a combination of a first step in which an aqueous alkali salt solution of an amino acid is obtained by reacting an aminonitrile and an alkali in an aqueous solution, and a second step in which an aqueous amino acid solution and an aqueous alkali solution are obtained by electrolytically ion-exchanging the same. Become.

Generally, for the hydrolysis reaction of aminonitrile, many alkaline substances such as barium hydroxide in addition to sodium hydroxide and potassium hydroxide can be used, but in the present invention, electrolytic ion exchange in the second step To facilitate this, either sodium hydroxide or potassium hydroxide must be used.

In the following, for the sake of simplicity, the case where sodium hydroxide is used will be explained, but all the descriptions also apply to the case where potassium hydroxide is used.

In the first step of the present invention, an aqueous solution of sodium hydroxide is added to an aqueous solution of aminonitrile, and the mixture is heated and stirred to cause a hydrolysis reaction of the nitrile group to produce an amino acid.

The resulting amino acid immediately neutralizes sodium hydroxide and becomes a sodium salt.

Most of the ammonia produced by the reaction evaporates and leaves the system.

This reaction has already been carried out in many industrial-scale examples, and proceeds smoothly under a wide range of reaction conditions.

The most common method for obtaining the raw material aminonitrile is glycolonitrile (HOCH2CN) for glycine.
For α-alanine, lactonitrile (CH3CH(
In the case of OH)CN)β-alanine, acrylonitrile (CH2=CHCN) is reacted with excess ammonia under normal pressure or increased pressure, which is widely practiced industrially.

The aminonitrile obtained by these methods contains, in addition to the ammonia that remains unreacted, the by-produced imino compounds, namely iminobisacetonitrile, α・α′-iminobispropionitrile, β・β′- It often contains iminobispropionitrile and the like, but as long as the amount is not particularly large, it can be used as is as a raw material for the method of the present invention.

Sodium hydroxide is 0.8% based on the nitrile group in the raw material.
Although it is necessary to use ~1.2 times the mole, the sodium hydroxide recovered in the second step can be mainly used for this purpose.

Then, only the missing amount that could not be recovered is made up with new sodium hydroxide.

The amount of water added to the reaction system is suitably adjusted so that the concentration of the amino acid salt produced in the reaction solution is in the range of 10 to 40 weight percent.

The reaction is carried out under normal pressure or slightly increased pressure, and the temperature is kept at the boiling point of the reaction solution in order to distill the produced ammonia out of the system, but as the reaction progresses, the rate of ammonia production slows down. The boiling point gradually rises and eventually reaches slightly above 100°C in a normal pressure reaction.

Although the entire amount of sodium hydroxide may be added initially, a higher yield may be obtained if it is added in small portions or in two or more portions.

The reaction time is usually about 0.5 to 5 hours, and it can be carried out either continuously or batchwise, but in the case of a continuous system, it is better to configure the apparatus to have two or more stages to make it more compact. can.

Ammonia production stops when all nitrile groups are hydrolyzed.

By further heating to evaporate water, the most convenient concentration for the next second step can be achieved.

The amino acid sodium salt aqueous solution obtained in the first step is subjected to electrolytic ion exchange in the second step to give an amino acid aqueous solution and a sodium hydroxide aqueous solution.

FIG. 1 is a system diagram of an example of equipment used for the second step.

The electrolytic cell in which the ion exchange reaction takes place has an anode 2 and a cathode 3.
This is a collection of unit cells 1 partitioned into eight chambers by placing two cation exchange membranes 4a and 4c between them (hereinafter referred to as the three-chamber method).

FIG. 2 shows a cell section partitioned into four chambers using three cation exchange membranes 4a, 4b, and 4c (hereinafter referred to as a four-chamber method).

Electrolyzers having such a configuration are commercially available and can be easily obtained.

The electrolytic ion exchange operation in the second step is performed as follows.

In FIG. 1, the anolyte is normally allowed to flow through the anolyte chamber 5 from the bottom to the top.

The anolyte is circulated through an anolyte tank 9.

The catholyte is normally allowed to flow through the cathode chamber 6 from the bottom to the top.

The catholyte is circulated through a catholyte tank 10. The amino acid sodium salt aqueous solution (hereinafter referred to as stock solution) obtained in the first step is passed through the ion exchange chamber 7 sandwiched between two cation exchange membranes, usually from the bottom to the top.

The stock solution is supplied from a stock solution supply tank 11 via a flow control valve 12 .

The liquid leaving the ion exchange chamber 7 (hereinafter referred to as a processing liquid) is sent to a processing liquid tank 13.

A part or all of the processing liquid may be circulated through the circulation path 14.

When using a four-chamber cell, two ion exchange chambers 7a
, 7e, the stock solution is supplied to the one 7c closer to the cathode and passed through the royal chamber in series.

A material with excellent corrosion resistance and electrical properties, such as titanium, is used for the anode.

For the anolyte, a mineral acid such as 2 to 15% by weight sulfuric acid is mainly used as a solution capable of generating hydrogen ions at the anode.

Most metals can be used for the cathode, but nickel-plated iron is the most economical.

For example, a 2 to 30% by weight aqueous solution of sodium hydroxide is used as the catholyte.

It should be noted that Figures 1 and 2 are for detailed explanation of the present invention, and show ordinary engineering means such as pumps, valves, measuring instruments, and other accessories that are not necessary for understanding the principle. things are omitted.

When a current is passed through the electrolytic cell that has been supplied with liquid as described above,
At the anode, water is decomposed into oxygen and hydrogen ions.

Oxygen is taken out of the room together with the anolyte and separated from the liquid in a separation chamber 15.

The hydrogen ions pass through the cation exchange membranes 4a and 4c and enter the ion exchange chamber 7, where they react with sodium salts of amino acids to become amino acids and liberate sodium ions.

This sodium ion passes through the cation exchange membrane 4c and enters the cathode chamber, so that the solution leaving the ion exchange chamber is free of sodium ions and becomes an amino acid solution.

At the cathode, water is split into hydrogen and hydroxide ions.

Hydrogen is taken out of the room together with the catholyte and separated from the liquid in the separation chamber 16.

The hydroxide ions electrically neutralize the sodium ions that have migrated from the ion exchange chamber to become sodium hydroxide, so the concentration of sodium hydroxide in the catholyte increases.

That is, the sodium in the stock solution was recovered as sodium hydroxide.

If ion exchange continues in this way, water will be lost from the anolyte due to the anodic reaction, so water is added to keep the concentration constant.

On the other hand, the acid in the anolyte does not participate in the reaction and does not move, so it neither increases nor decreases.

Therefore, the anolyte can be used semi-permanently by simply adding water.

While water is lost in the catholyte due to the cathode reaction, sodium hydroxide increases, so if water is added to keep the concentration approximately constant, the amount of liquid will increase according to the amount of sodium hydroxide recovered. .

Therefore, the solution is taken out of the system either continuously or intermittently.

The sodium hydroxide solution taken out of the system can be used again in the first step as it is without any treatment such as purification.

From the above description, it is clear that in the present invention, alkali is recovered, acid is not consumed, and no waste liquid is produced.

When the solution is alkaline, amino acids become anions even if they are charged, so they do not pass through the cation exchange membrane and move into the polar liquid.

As ion exchange progresses and the pH value of the solution becomes lower than the isoelectric point, some of the amino acids become cations, but they do not move to the anode side against the potential difference, and almost all of them end up on the cathode side. Move to.

In the pressure chamber method, in order to prevent this, the pH value of the treatment liquid is managed so as not to fall significantly below the isoelectric point.

However, in the present invention, even if the pH value falls below the isoelectric point, the amino acids that have migrated into the catholyte can be returned to the system by reusing the recovered sodium hydroxide in the first step. Since it returns, there is no loss, and the current efficiency only slightly decreases.

Therefore, the pH value management of the treatment liquid does not need to be as strict as in the case of electrodialysis.

Further, it is usually not necessary to carry out ion exchange close to the isoelectric point.

That is, the amount of sodium ions that are allowed to remain in the treatment solution depends on the operating method of subsequent steps, but is usually not so small.

From the above, it is sufficient that the pH value of the treatment liquid is controlled within a fairly wide range.

When it is desired to increase the ion exchange rate and prevent the permeation of amino acids, an electrolytic cell using the concave chamber method is useful.

In the concave chamber method, the liquid in the ion exchange chamber 7c closer to the cathode can always be kept alkaline, so even if the ion exchange chamber 7a on the anode side becomes acidic and cationized amino acids move from there, It is neutralized here and does not proceed further to the cathode side.

However, since the concave chamber method requires a higher interelectrode voltage than the pressure chamber method, it is desirable to devise ways to use the pressure chamber method as much as possible.

In the present invention, since the ion exchange chamber is partitioned by a cation exchange membrane, no permeation of hydroxide ions occurs.

Therefore, water movement takes place only by molecular diffusion.

Therefore, by maintaining the bipolar solution at an appropriate concentration and controlling the pressure in the bipolar chamber so that it does not become higher than the pressure in the ion exchange chamber, it is possible to prevent water from permeating from the bipolar chamber to the ion exchange chamber. Instead, by permeating water from the ion exchange chamber to the bipolar chamber, it is possible to supplement the water lost by electrolysis and at the same time obtain a concentrated treatment liquid.

Therefore, compared to conventional methods, energy consumption in subsequent steps is reduced.

As a method for controlling the operation of the method of the present invention, for example, there is a method of controlling the supply amount of the stock solution so that the ion exchange rate of the treatment solution falls within a predetermined range while passing a constant current.

There are various methods for measuring the ion exchange rate, but this can be replaced by measuring the pH value as described above.

That is, it is convenient to determine the relationship between the ion exchange rate and pH value of the treatment liquid in advance, and to perform process control using the pH value corresponding to the required exchange rate.

The method of measuring the pH value and controlling the flow rate using the method is well established in engineering and has high reliability, so continuous automatic operation can be performed easily and safely in martial arts.

The factors that determine the power consumption in the electrolytic ion exchange method of the present invention are: (a) the amount of sodium ions to be ion-exchanged;
(b) current efficiency; and (e) interelectrode voltage.

Next, the equipment and operating conditions that influence these three factors will be explained.

The amount of sodium ions to be ion-exchanged is basically determined by the amount of sodium ions contained in the stock solution, and the amount is usually approximately equimolar to or slightly more than the amino acid.

However, in reality, sodium ions are allowed to remain to the extent that they do not interfere with subsequent steps, so power can be saved by keeping the ion exchange rate to the minimum necessary.

Furthermore, by neutralizing the remaining sodium ions with an acid, an even lower ion exchange rate may be required.

In this case, do not remove the salt that has formed and proceed to the next step.

If the ion exchange rate is lowered, the amount of sodium hydroxide recovered will naturally decrease, so the optimum exchange rate must be found by comparing it with the electricity cost.

The electrical conductivity of an aqueous amino acid solution decreases rapidly as it approaches its isoelectric point.

Therefore, unless the voltage is increased, the required current cannot flow, resulting in increased power consumption for the same amount of ion exchange.

By the way, if acidic impurities are present in the stock solution to a certain extent or more, even if the ion exchange progresses to near the isoelectric point of the amino acid, the electrical conductivity will not decrease much and the ion exchange will continue smoothly.

Furthermore, as described above, acidic impurities do not pass through the cation exchange membrane and reach the electrodes, so current efficiency does not decrease.

Taking advantage of this, by intentionally adding a small amount of acid to the stock solution, it is possible to prevent the electrical conductivity from decreasing as ion exchange progresses, increasing the capacity of the device and saving power. .

As the acid added for this purpose, in addition to mineral acids such as sulfuric acid, organic acids such as acetic acid can also be used, but the amount must be kept within a range that does not interfere with subsequent steps.

Usually, a sufficient effect can be obtained by adding 0.0001 to 0.1 parts by weight per 1 part of the raw material.

Further, when it is desired to increase the ion exchange rate, the following method is also effective as a method for avoiding disadvantages such as a decrease in device capacity or an increase in power consumption due to a decrease in the electrical conductivity of the solution.

That is, the ion exchange by the method of the present invention is limited to a range in which the electrical conductivity of the treatment liquid is sufficiently high, and the remaining sodium ions are continuously removed by applying the usual ion exchange resin method or electrodialysis method. and remove it.

A treatment solution with an ion exchange rate of, for example, 80 to 95 percent has several times or more of conductive dust than a solution that has been completely exchanged.

Therefore, by keeping the ion exchange rate to this level, illegal electrolysis/ion exchange can be operated at a high current density even at a relatively low voltage, so the electrolytic cell can be made smaller.

On the other hand, in the subsequent ion exchange resin method or electrodialysis method, the amount of sodium ions to be exchanged is only 5 to 20% of the conventional method, so the resin regeneration frequency is low in the resin method, and the electrodialysis method In this case, the salt concentration of the solution to be treated is low and the dialysis time is short.

Therefore, among the drawbacks of conventional methods, such as a decrease in yield, generation of waste liquid, decrease in concentration of processing liquid, and consumption of resin, etc., are greatly reduced.

Of course, the sodium is mostly recovered as useful sodium hydroxide.

This method is particularly effective when applied to conventional plants, since it can effectively utilize conventional equipment and reduce equipment investment for electrolysis.

As the cation exchange membrane in the present invention, commercially available ordinary ones can be used, but power consumption can be reduced by selecting one that has excellent ion permselectivity and low electrical resistance.

Note that the membrane installed closest to the cathode must be alkali-resistant, and the membrane installed closest to the anode must be acid-resistant.

The smaller the distance between each electrode and the membrane and the distance between the membranes, the smaller the power loss due to the electrical resistance of the solution, but it is technically difficult to make them too small, and Since the diameter also increases, it is usually kept within the range of 1 to 5 mm.

In the method of the present invention, even if various measures are combined as described above, it is inevitable that a considerable amount of power will be consumed.

The power required to recover 1 kilogram of sodium hydroxide varies widely depending on the performance and operating method of the equipment, but if equipment is selected and operated properly, it will be 2 to 6 kW.
It will be in the H range.

The value of the sodium hydroxide combined with the value of not consuming the acid is believed to more than compensate for the power costs.

If we evaluate the above-mentioned effects such as high yield, no pollution, energy saving, and rationalization of operation management, the advantages of the present invention compared to conventional methods cannot be overstated. The significance of this invention is great.

For simplicity, the case where sodium hydroxide is used as the alkali has been described above, but all the descriptions apply similarly to the case where potassium hydroxide is used.

In particular, since potassium hydroxide is more expensive than sodium hydroxide, it is even more significant that it can be recovered by employing the method of the present invention.

The first step in the method of the present invention is already a well-developed technology, but by combining it with the newly developed second step, great effects are brought about, as already mentioned, glycine, α- Amino acids such as alanine and β-alanine can now be produced at lower cost.

Next, examples will explain how the invention can be implemented.

The electrolytic cell used in the following examples had an effective area of 100 cm for both electrodes and cation exchange membranes, and the electrodes and membranes and the membranes were kept at a distance of 2 mm from each other.

The anode is made of titanium with an oxide coating on its surface, and the cathode is iron.

The ion exchange membrane 4a closest to the anode is 61AZL manufactured by Ionics, and the membrane 4c closest to the cathode is Nafion 215 manufactured by DuPont.

The central membrane 4b in the case of the concave chamber method is Nafion 315 manufactured by DuPont.

The anolyte is approximately 1N sulfuric acid, and the catholyte is approximately 2N aqueous sodium hydroxide.

The electrolytic cell was operated at a current density of 0.12 amperes per 1 cm2 of effective area. Both electrode solutions were constantly circulated in such an amount that the concentration change before and after each operation was within 20% of the original concentration. I didn't add any water in between.

Example 1 9.5% sodium hydroxide aqueous solution was added to 1000 g of an aqueous solution containing 14% α-aminopropionitrile (all percentages by weight are used below) and 2.3% α・α′-iminobispropionitrile. Ammonia and water were distilled off while adding 1030 g at once and heating and stirring.

This aqueous sodium hydroxide solution was recovered in a previous experiment and contained 1.1% α-alanine.

When the reaction was completed and the liquid temperature reached 102°C, heating was stopped.

In this way, 1171 g of an aqueous solution containing 19.9% of the sodium salt of α-alanine was obtained.

The reaction yield was 98.7%.

This aqueous solution was ion-exchanged using a pressure chamber electrolytic cell.

The supply amount of the stock solution was adjusted so that the pH value of the treatment solution was in the range of 6 to 7.

For 2 hours when steady state was maintained, the supply amount of stock solution was 41
386 g of treatment liquid was obtained for 1 g.

The average voltage during this period was 6.5V.

From the analysis results of the treatment liquid and catholyte, the ion exchange rate, that is, the recovery rate of sodium hydroxide, was 94.5%, and the yield of α-alanine in the treatment liquid was 95.3%.

When the α-alanine that had migrated into the catholyte was added, the yield was approximately 100%.

Current efficiency was 86.7%.

The power required per 1 kg of recovered sodium hydroxide is 5
．． It was 2KWH.

Further, the α-alanine concentration in the treatment solution was 16.2%, which was about 1.9 times the concentration of a solution normally obtained by the ion exchange resin method.

This treated solution was concentrated, crystallized, filtered and dried in a conventional manner to obtain 54 g of α-alanine crystals.

The quality was equivalent to that obtained by conventional methods, and of course it fully passed the food additive standards.

Example 2 In the method of Example 1, the pH value of the electrolytic treatment solution is 8.
．． The amount of stock solution supplied was adjusted to be in the range of 3 to 8.5.

A comparison of the results is shown in the table below. As can be seen from the above table, by lowering the ion exchange rate, the processing capacity of the electrolytic cell improves and the power consumption rate decreases.

After passing 300 g of the obtained treated liquid through a cylinder filled with 50 ml of H+ type cation exchange resin (Diaion WK-20), the remaining liquid was extruded with 50 ml of water, and the entire amount of the obtained liquid was concentrated and crystallized. After analysis, filtration and drying, 40 g of α-alanine crystals were obtained.

On the other hand, the resin was regenerated with 130 ml of normal sulfuric acid and then washed with 50 ml of water.

The regeneration liquid and washing liquid were combined and used as waste liquid.

Compared to the case where the entire treatment is done with ion exchange resin without electrolytic ion exchange, the amount of cation exchange resin used and the amount of waste liquid are both one-fifth for each unit amount of α-alanine obtained. The COD load was one-third, and the amount of alanine lost to the waste liquid was about one-seventh.

Moreover, the concentration of the alanine aqueous solution obtained was about 1.6 times.

Example 3 In the partial electrolytic ion exchange of Example 20, 80.
1N hydrochloric acid was added to 2500 g of the liquid ion-exchanged to 3% to neutralize the remaining sodium ions, and the pH value was adjusted to 6.0.

This was desalted using a commercially available electrodialysis device (Model DU-06 manufactured by Asahi Glass Co., Ltd.).

A 3% NaCl aqueous solution was used as the electrode solution of the dialysis device, and a 0.7% NaCl aqueous solution 21 was used as the concentrated solution.

This device had 9 sample chambers and 10 concentration chambers, the membrane spacing between each chamber was 2 mm, and the effective area of the membrane was approximately 200 cm2.

The sample liquid was circulated through the tube while maintaining the sliding voltage at 15V.

The sample solution was desalted until the NaCl concentration reached 11,000 pp.

The alanine yield in the desalted solution was 97.8%.

Concentrate NaCl concentration is 3.7%, COD value is 11050
Assuming that the concentrated waste liquid is discharged with the same concentration of NaCl (pp), the results are as follows when compared with the conventional method, which uses only neutralization and electrodialysis without using electrolytic ion exchange.

That is, for every 1 kg of alanine produced, in this example, the amount of waste liquid was one-fifth, the COD load in the waste liquid was one-half, and the amount of alanine lost to the waste liquid was about one-third.

Example 4 An aqueous solution containing 17% sodium salt of glycine was used as a stock solution and treated in a three-chamber electrolytic cell.

The supply amount of the stock solution was adjusted so that the pH value of the treatment solution was in the range of 7 to 8.

Processing capacity per hour is 227g of stock solution, voltage is 7.6
■It was.

The ion exchange rate was 97.2%, the current efficiency was 75.5%, and the glycine yield in the treated solution was 87.4%.

Example 5 The stock solution used in Example 4 was treated in a concave non-electrolyzed tank.

The supply amount of the stock solution was adjusted so that the pH value of the treatment solution was 6 to 6.5.

Processing capacity per hour is 227g of stock solution, voltage is 9.1
It was V.

The ion exchange rate was 99.6%, the current efficiency was 88.5%, and the glycine yield in the treated solution was 100%.

Example 6 While continuing the operation as in Example 4, 0.0% was added to the stock solution.
Acetic acid was added at a rate of 7%.

The voltage, which was 9.1 V, was lowered to 7.5 V, and the processing capacity was improved by about 10% to 251 g of stock solution per hour.

The ion exchange rate was 94.2%, the current efficiency was 92.6%, and the glycine yield in the treated solution was 100%.

Example 7 Aqueous solution 1000 containing 10% β-aminopropionitrile and 1.2% β·β′-iminobispropionitrile
630 g of a 14% aqueous solution of potassium hydroxide was added to the solution, and while gradually heating and stirring, ammonia and water were distilled off.

Heating was stopped when the generation of ammonia ended and the liquid temperature reached approximately 102°C.

In this way, 1240 g of an aqueous solution containing 14.5% potassium salt of β-alanine was obtained.

The reaction yield was 99.1%.

This aqueous solution was ion-exchanged using a three-chamber electrolytic cell.

However, a 14% aqueous solution of potassium hydroxide was used as the catholyte.

The supply amount of the stock solution was adjusted so that the pH value of the treatment solution was in the range of 7 to 8.

For 2 hours of steady state, the stock solution supply amount was 7
660 g of treatment liquid was obtained using 11 g.

The average voltage during this period was 6.2V.

From the analysis results of the treatment liquid and catholyte, the ion exchange rate, that is, the recovery rate of potassium hydroxide, was 95.3%, and the yield of β-alanine in the treatment liquid was 95.7%.

When β-alanine that had migrated into the catholyte was added, the yield was approximately 100%.

Current efficiency is 92.3%, recovered potassium hydroxide 1k
The required power per g was 3.3 KWH.

Concentration, crystallization, filtration, and drying are performed from this treated solution in the usual manner to obtain β-alanine crystals with a purity of 98% or more.
I got g.

The quality of the recovered catholyte, ie, potassium hydroxide aqueous solution, was such that it could be used as is in the first step.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the principle when a royal method cell is used in the electrolytic ion exchange apparatus used in the second step of the present invention, and FIG. 2 is a diagram showing the principle when a concave chamber method cell is used. In the figure, 1 is an electrolytic cell, 2 is an anode, 3 is a cathode, and 4a
, 4b and 4c are cation exchange membranes, 5 is an anode chamber, 6 is a cathode chamber, 7° 7a and 7c are ion exchange chambers, 8 is a circulation rate control valve, 9 is an anolyte tank, 10 is a catholyte tank, 1
1 is a stock solution tank, 12 is a flow rate control valve, 13 is a fertilization solution tank, 14 is a circulation path, and 15 and 16 are separation chambers.

Claims (1)

[Scope of Claims] 1. In an aqueous solution containing aminoacetonitrile, α-aminopropionitrile or β-aminopropionitrile,
A first step of obtaining an aqueous solution of sodium salt or potassium salt of glycine, α-alanine or β-alanine by adding an aqueous solution of sodium hydroxide or potassium hydroxide and stirring with heating, and two or three sheets between the two electrodes. An aqueous solution of mineral acid is passed through the anode chamber of an electrolytic cell equipped with a cation exchange membrane as a diaphragm, and an aqueous solution of sodium hydroxide or potassium hydroxide is passed through the cathode chamber. By passing the aqueous amino acid salt solution obtained in the first step through the chamber and performing electrolytic ion exchange, an aqueous solution of glycine, α-alanine, or β-alanine is obtained, and at the same time, sodium hydroxide or potassium hydroxide is added to the catholyte. 1. A method for producing glycine, α-alanine or β-alanine, which comprises a second step of producing and recovering glycine, α-alanine or β-alanine. 2. The method according to claim 1, in which 0.0001 to 0.1 part of acid is added to 1 part of the amino acid salt aqueous solution for electrolytic ion exchange. 3. To an aqueous solution containing aminoacetonitrile, α-aminopropionitrile or β-aminopropionitrile,
A first step of obtaining an aqueous solution of sodium salt or potassium salt of glycine, α-alanine or β-alanine by adding an aqueous solution of sodium hydroxide or potassium hydroxide and stirring with heating, and two or three sheets between the two electrodes. An aqueous solution of mineral acid is passed through the anode chamber of an electrolytic cell equipped with a cation exchanger as a diaphragm, and an aqueous solution of sodium hydroxide or potassium hydroxide is passed through the cathode chamber. By passing the aqueous amino acid salt solution obtained in the first step through and performing partial electrolytic ion exchange, an aqueous solution containing glycine, α-alanine, or β-alanine as its main components is obtained, and at the same time, hydroxylation is added to the catholyte. It is characterized by comprising a second step of producing and recovering sodium or potassium hydroxide, and an additional step of contacting the aqueous solution obtained in the second step with an H-type cation exchange resin. glycine, alpha-alanine or beta
-A method for producing alanine. 4 Into an aqueous solution containing aminoacetonitrile, α-aminopropionitrile or β-aminopropionitrile,
A first step of obtaining an aqueous solution of sodium salt or potassium salt of glycine, α-alanine or β-alanine by adding an aqueous solution of sodium hydroxide or potassium hydroxide and stirring with heating, and two or three sheets between the two electrodes. An aqueous solution of mineral acid is passed through the anode chamber of an electrolytic cell equipped with a cation exchange membrane as a diaphragm, and an aqueous solution of sodium hydroxide or potassium hydroxide is passed through the cathode chamber. By circulating the aqueous amino acid salt solution obtained in the first step through the chamber and performing partial electrolytic ion exchange, an aqueous solution containing glycine, α-alanine, or β-alanine as the main component is obtained, and at the same time, water is added to the catholyte. A glycine characterized by comprising a second step of producing and recovering sodium oxide or potassium hydroxide, and an additional step of neutralizing the aqueous solution obtained in the second step by adding a mineral acid. , a method for producing α-alanine or β-alanine. 5. To an aqueous solution containing aminoacetonitrile, α-aminopropionitrile or β-aminopropionitrile,
A first step of obtaining an aqueous solution of sodium salt or potassium salt of glycine, α-alanine or β-alanine by adding an aqueous solution of sodium hydroxide or potassium hydroxide and stirring with heating, and two or three sheets between the two electrodes. An aqueous solution of mineral acid is passed through the anode chamber of an electrolytic cell equipped with a cation exchange membrane as a diaphragm, and an aqueous solution of sodium hydroxide or potassium hydroxide is passed through the cathode chamber. By passing the aqueous amino acid salt solution obtained in the first step through the chamber and performing partial electrolytic ion exchange, an aqueous solution containing glycine, α-alanine, or β-alanine as its main components is obtained, and at the same time hydroxylation is carried out in the catholyte. a second step of generating and recovering sodium or potassium hydroxide; a mineral acid is added to the aqueous solution obtained in the second step to neutralize it; and the neutralized aqueous amino acid solution is subjected to electrodialysis. A method for producing glycine, α-alanine or β-alanine, which comprises an additional step of desalting.