JPS5846551B2 - Method for producing amino acids from amino acid alkali metal salts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Among amino acids, those having the same number of amino groups and carboxy groups are generally called neutral amino acids.

The present invention relates to a method for obtaining amino acids from alkali metal salts of neutral amino acids (hereinafter referred to as alkali salts).

When producing various neutral amino acids by synthetic methods or fermentation methods, it is often the case that an alkali salt of the amino acid is first obtained and then converted into an amino acid.

The conversion of alkali salts into amino acids is usually carried out by (1) contacting with an H-type cation exchange resin, (2) adding an inorganic acid to form a mixture of amino acids and inorganic salts, and then desalting by crystallization or electrodialysis. carried out by any of the following methods:

However, in these methods, an approximately equivalent amount of acid to the alkali metal ion contained in the raw material is consumed, and both become salts and are contained in the waste liquid.

Therefore, an ion exchange membrane electrolysis method has been developed as a method that does not consume acid and recovers alkali, and therefore does not produce waste liquid containing a large amount of salt.

This is a three-compartment electrolytic cell in which a diaphragm consisting of two cation permselective membranes (hereinafter referred to as cation membranes) is installed between the cathode and anode electrodes, and an aqueous solution of an inorganic acid is placed in the anode chamber and in the cathode chamber. In this method, an aqueous solution of an alkali hydroxide is passed through each, and an aqueous solution containing an amino acid alkali salt as a raw material is passed through an ion exchange chamber separated from both electrodes by two cation membranes, and electricity is applied to the ion exchange chamber. Amino acids are obtained in the ejected liquid, and alkali is recovered as hydroxide in the catholyte.

This method is an excellent method that does not generate waste liquid and can obtain amino acids as a highly concentrated solution, but the only drawback is that it consumes a lot of power when applied to neutral amino acids.

This is because the conductive dust in the neutral amino acid aqueous solution is small.

That is, as the conversion progresses and the amount of amino acids increases and the amount of alkali ions decreases, the amount of conductive dust in the solution decreases.

This increases the electrical resistance of the ion exchange chamber and increases the power required for electrolysis.

This disadvantage arises when increasing the ion exchange rate, that is, the recovery rate of alkali, or when handling solutions with low concentrations due to the low solubility of amino acids in water.
It becomes even more noticeable.

The present invention provides an ion exchange membrane electrolysis method with low power consumption.

The feature is that a mixed solution of amino acids and supporting salt (hereinafter referred to as supporting salt) is added to a solution containing the raw material amino acid alkali salt and a salt for increasing conductive dust (hereinafter referred to as supporting salt) is electrolyzed.
After obtaining an ion exchange solution (referred to as an ion exchange solution), amino acids are precipitated as crystals from this by a normal crystallization operation, and the crystals are separated from the supporting salt by separation in a furnace.

This method is based on the following two points: (1) Adding a small amount of a certain kind of salt greatly increases the electrically conductive dust in the amino acid aqueous solution, and (2) All salts that are effective as supporting salts are highly soluble in aqueous solvents, so crystallization is required. This takes advantage of the fact that it is easy to separate from amino acids.

For example, a 15% aqueous solution of α-alanine at 25°C.
The conductive dust in the is about 40μmhOA, but by adding O, ISg/100'rrLl of sodium sulfate, which corresponds to only 1% of the α-alanine contained, the conductive dust becomes about 1500μmho/cm. Become.

Furthermore, the solubility of α-alanine at 25°C is approximately 16g.
7100-, whereas the solubility of sodium sulfate is about 21g/100ml, highly pure α-alanine can be obtained by crystallization even if the amount of sodium sulfate added is considerably larger than in the above inversion. .

FIG. 1 is a conceptual flow diagram of a process applying the present invention.

FIG. 2 is a conceptual diagram of the structure of a unit cell constituting the ion exchange membrane electrolyzer.

Hereinafter, the present invention will be described in detail according to these drawings.

The amino acid alkaline salt aqueous solution in the raw material tank 1 and the solid or aqueous supporting salt are mixed in the raw material tank 2 to form a stock solution.

An anolyte A consisting of an aqueous solution of an inorganic acid, such as sulfuric acid, is circulated through the anode chamber 32 of each cell of the electrolyzer 3.

In the cathode chamber 34, normally, a catholyte C consisting of an aqueous solution of alkali hydroxide of the same type as the alkali constituting the raw amino acid salt, for example, an aqueous solution of sodium hydroxide when the raw material salt is a sodium salt, is circulated.

When the stock solution F is passed through the ion exchange chamber 36 while applying direct current to the electrolytic cell, the hydrogen ions generated by the anode reaction permeate the cation selectively permeable membrane 35a and enter the ion exchange chamber 36.
enters the amino acid salt and replaces the alkaline cation (eg, sodium ion) to yield the amino acid, liberating the alkaline cation.

The liberated alkali cations pass through the cation membrane 35c and enter the cathode chamber.

The resulting solution containing amino acids is taken out as ion exchange solution B.

The alkali cations entering the cathode chamber meet the hydroxide ions produced by the cathode reaction, producing alkali hydroxide (eg, sodium hydroxide).

The above mechanism is already well known, and examples of its implementation have also been reported.

Hereinafter, this method will be referred to as electrolytic ion exchange.

Descriptions of matters common to the operating method of conventional electrolyzers, such as the need to replenish water to both electrodes, will be omitted.

A feature of the present invention is that a supporting salt is added to the stock solution.

As the acid constituting the supporting salt, an acid that is more acidic than the amino acid to be produced is selected, except in special cases described later.

Further, as the alkali constituting the supporting salt, it is usually convenient to select an alkali of the same type as the alkali constituting the raw material amino acid salt.

Therefore, for example, when trying to obtain alanine and sodium hydroxide from the sodium salt of alanine, the supporting salts are sodium chloride, sodium sulfate, sodium phosphate, sodium acetate, sodium lactate, sodium oxalate, imino-di-propion. Sodium acid, etc. can be used.

The supporting salt may also be a mixture of these salts.

When a stock solution containing such a supporting salt is subjected to electrolytic ion exchange,
Less acidic amino acids occur preferentially, and the supporting salt remains as a salt.

If ion exchange is stopped when all of the amino acid salts have been converted to amino acids, a mixed solution of amino acids and supporting salts, ie, an ion exchange solution, can be obtained.

Even at this point, the solution remains highly conductive due to the dissolved supporting salts.

Therefore, the voltage required for electrolysis is lower than without the addition of a supporting salt, and the power consumption is proportionally lower.

The alkali obtained in the catholyte by electrolytic ion exchange is
It can be used again in the process of producing amino acid alkali salts.

In order to obtain amino acids from the ion exchange solution, the solution is appropriately concentrated if necessary, and then the amino acids are precipitated and separated in a furnace.

Methods for precipitating amino acids include a method of (concentrating) and cooling a solution, and a method of adding an alcohol such as methanol or ethanol.

Which one is suitable depends on the combination of amino acid and supporting salt, the amount of supporting salt added, and the type and amount of other impurities.

The remaining mother liquor enriched with amino acids can be discarded, but since some amino acids are usually dissolved in the mother liquor together with the supporting salt, at least a portion of the mother liquor can be reused as a stock solution, either as is or after being concentrated. By adding both the supporting salt and the amino acid may be recovered.

Alternatively, after concentrating the mother liquor, most of the amino acids and supporting salts may be precipitated by cooling or adding alcohol, separated in a furnace, and then added to the stock solution again.

This operation is called "second crystallization." According to this method, most of the amino acids and supporting salts are recovered, and other impurities contained in the raw salt are dissolved in the mother liquor of the second crystallization. It can also be taken outside.

The above is the principle of the present invention, but in order for the method of the present invention to be applicable, the amino acids to be handled must have a certain level of water solubility.

Generally, alkaline salts of amino acids have high water solubility, but
When it comes to amino acids, the solubility decreases.

Therefore, the concentration of the stock solution must be adjusted so that the concentration of amino acids produced by electrolytic ion exchange does not exceed the saturated solubility.

This is because the structure of general electrolyzers is not suitable for handling liquids containing solids.

On the other hand, if the concentration of the solution is too low, even if a supporting salt is added, the conductivity will be low, making it inappropriate to apply electrolytic ion exchange.

This is because there is a limit to the ratio of the supporting salt to the amino acid in the solution in order to efficiently obtain a highly pure amino acid through the subsequent crystallization operation.

The solubility of the amino acid can be increased by increasing the temperature of the solution, but if the durability of the electrodes and cation membrane is considered, the upper limit is about 80°C.

Therefore, the amino acids to which the present invention can be applied include 8
It is desirable that the water solubility at 0° C. is at least 0.2 mol/l.

Examples of neutral amino acids that meet this condition include alanine, glycine, threonine, phenylalanine, valine,
There are many examples, such as methionine and sarcosine, and the present invention can be applied to all of them.

On the other hand, as alkali ions constituting amino acid salts, sodium ions and potassium ions are easily applicable to the present invention.

Next, as acids constituting the supporting salt, in addition to all water-soluble inorganic acids and carboxylic acids, amino acids and iminodicarboxylic acids that are more acidic than the amino acids to be handled are also effective.

The alkali ions constituting the supporting salt are preferably sodium ions or potassium ions, and it is usually convenient to use the same type of alkali as the alkali constituting the raw material amino acid salt.

Note that the supporting salt may be a mixture of two or more types of salts, each of which satisfies each of the above conditions.

Furthermore, instead of adding salt, an acid may be added to form a salt with some of the alkali ions in the raw material.

However, in this case, the alkali equivalent to the added acid is not recovered, so the alkali recovery rate is low.

Of course, the acid is not recovered either.

In special cases of the present invention, the raw amino acid salt solution may initially contain a salt that meets the above conditions as an impurity.

For example, when producing alanine, glycine, etc. by the Strecker reaction, the reaction solution contains a small amount of the corresponding imino-di-carboxylic acid salt along with the alkali salt of these amino acids.

According to the principle of the present invention, it is better to electrolyze such impurities without removing them.

That is, these impurities can be used as a supporting salt or a part of a supporting salt.

In another special case of the present invention, the raw amino acid salt itself is utilized as the supporting salt.

In other words, this corresponds to partial electrolytic ion exchange to prevent all of the amino acid salt from being converted into amino acids, and allows the amino acid salt remaining without ion exchange to act as a supporting salt.

Then, a portion of the amino acid is extracted as a crystal by utilizing the difference in solubility between the amino acid and the amino acid alkali salt.

The mother liquor in which the remaining amino acids and amino acid salts are dissolved is concentrated if necessary and returned to the electrolytic ion exchange process.

That is, a part of the amino acid salt as a raw material circulates within the system and acts as a supporting salt.

Of course, other supporting salts may also be present.

If the amount of supporting salt in the stock solution is large, the electrical conductivity will be high and the power required for electrolytic ion exchange will be reduced, but if the supporting salt concentration is too high, there is a risk that the supporting salt will be mixed into the amino acid crystals obtained during crystallization. be.

Furthermore, if the raw materials contain impurities, they must be taken out of the system, and at least a portion of the mother liquor or second mother liquor must be discarded.

Correspondingly, there is some loss of supporting salts and sometimes also of amino acids.

The higher the concentration of supporting salt, the greater its loss tends to be.

The amount of supporting salt to be added must be determined taking the above into account, but its optimal concentration is usually 0.03 to 1 equivalent/l.
within the range of

The anode of the electrolytic device used in the present invention has excellent electrical properties and corrosion resistance.

For example, one known as the trade name DSE may be used.

The cation membrane 35a on the anode side is required to have acid resistance, and the cation membrane 35c on the cathode side is required to have alkali resistance, and such membranes are also commercially available.

For example, there are perfluorosulfonic acid films and perfluorocarboxylic acid films.

Most metals can be used for the cathode, but iron is the cheapest.

There are also commercially available devices in which a large number of three-chamber electrolysis cells made of such materials are assembled to perform electrolysis on an industrial scale.

Operating methods for the process of electrolytically ion-exchanging the stock solution containing a supporting salt include (1) the so-called batch circulation method in which the stock solution is circulated and electrolysis is continued until the required ion exchange rate is reached;
) The so-called one-pass method, in which the stock solution is temporarily treated and the supply amount or current supply amount of the stock solution is adjusted to achieve the desired ion exchange rate;
(3) Methods such as a partial circulation method in which a portion of the ion-exchanged solution is added to the stock solution are possible, but which method is best depends on the material being handled, the situation of peripheral equipment such as storage tanks, and the power supply situation. They differ and must be considered on a case-by-case basis.

Ideally, the ion exchange rate should be such that only the target amino acid is completely converted to the amino acid and the supporting salt remains as is, but there is often no particular disadvantage even if there is a slight excess or deficiency.

To know the ion exchange rate and control the process, it is usually most convenient to measure the pH value of the liquid exiting the electrolyzer.

This is because the relationship between the ion exchange rate and the pH value is uniquely determined by the composition of the stock solution.

Except for special cases, ion exchange may be performed until the pH value is close to the isoelectric point of the amino acid.

At this time, the amino acid salt in the solution is almost completely converted into amino acids, and the supporting salt remains as it is.

If ion exchange is carried out any further, the supporting salt will also be decomposed and acid will begin to be produced.

Therefore, near the isoelectric point, a slight change in the ion exchange rate causes a large change in the pH value, so it is easy to detect that the required ion exchange rate has been reached, and accurate process control is possible.

Since the iso-point of neutral amino acids lies in the pH range of 5 to 8, the solution does not become strongly acidic until the ion exchange is complete.

Therefore, hydrogen ions hardly migrate to the cathode chamber, and electrolysis is performed with high current efficiency.

However, if electrolysis is continued past the isoelectric point, the supporting salt decomposes and the solution becomes acidic, and hydrogen ions move from the ion exchange chamber to the cathode chamber, producing a reactive current and reducing current efficiency.

In order to prevent this, it is convenient to control the operation based on the pH value of the ion exchange solution.

Normally, it is desirable to manage this pH value so that it does not fall below 4.

As mentioned earlier as one of the special cases, if part of the amino acid salt is left without ion exchange, the electrolysis will naturally end at a pH value higher than the isoelectric point of the amino acid, resulting in high current efficiency. It will be done.

Another effect of the present invention is improved current efficiency.

When electrolytic ion exchange is operated at a high ion exchange rate, the amount of stock solution supplied to each part of the electrolyzer must be uniform.

For example, if there is a difference in the supply amount between multiple cells electrically connected in series, the amount of salt supplied will be different even though the amount of current flowing through each cell is the same, so a large supply amount The ion exchange rate will be lower in the cell, and the voltage will be higher in the cell with less supply.

In order to increase the ion exchange rate of the former, a higher voltage must be applied and an extra current must flow for the latter, resulting in a decrease in current efficiency.

Although it is difficult to make the flow distribution in an electrolytic cell highly uniform, if ion exchange is performed using the method of the present invention, part of the supporting salt decomposes in areas where the flow rate is low, producing acid. Since the acid neutralizes the alkali remaining in the areas where the flow rate is high, it is possible to prevent a decrease in current efficiency due to uneven flow rates.

If the current efficiency is high, the amount of current can be reduced, so
Naturally, the voltage will also be lower.

In this way, lower aliphatic monocarboxylate salts such as acetic acid and phosphorus are especially suitable as supporting salts used not only to lower the voltage by providing conductive dust but also to prevent problems caused by uneven flow rates. It is a salt of a highly water-soluble weak acid such as an acid salt.

This is because even if these supporting salts decompose to produce acids, the pH value of the solution does not become too low.

Crystallizing amino acids from an ion exchange solution involves concentration and
Both the cooling method and the alcohol addition method are widely used, and the principles do not seem to require any special explanation.
Specific operating conditions must be considered based on the required purity of the amino acid and the amount of impurities contained in the raw material.

However, in any case, it is easy if the amount of supporting salt added is not large.

The effect of the present invention in saving electrolytic power will be greater if the existing knowledge regarding crystallization operations is utilized to allow for as high a supporting salt concentration as possible.

As long as there are not particularly many impurities in the raw materials, most of the amino acids and supporting salts in the mother liquor can be recovered and reused.

As explained above, the present invention has the following features: (1) The conductivity of a neutral amino acid aqueous solution is low, but by adding a small amount of supporting salt to it, the conductivity can be greatly increased; (2) Three-chamber electrolysis Amino acid salts can be converted to amino acids with high current efficiency by electrolytic ion exchange while controlling the pH value of the ion exchange solution to not fall significantly below the isoelectric point of the amino acid using a device; (3) As a supporting salt. This method takes advantage of the fact that all salts that satisfy the following conditions have high solubility, so amino acids can be crystallized and separated from supporting salts.

The present inventors have completed the present invention by discovering that the efficiency of electrolytic ion exchange can be greatly increased by applying the above principle only in the case of alkaline salts of neutral amino acids.

For reference, the conductivity of an aqueous solution of acidic or hydrochloric acidic amino acids or general acids is much higher than that of neutral amino acids, so there is no point in applying the present invention.

Next, a specific method for carrying out the present invention and its effects will be described in more detail with reference to Examples.

In the following examples, unless otherwise specified, electrolysis was carried out under the following conditions.

Anode: DSB Cathode diiron cation membrane: Nafion Effective area of electrode and membrane: 100i Anolyte: Approximately 5% sulfuric acid Catholyte: 5-10% sodium hydroxide Current density: 0.176 amps/cell operation Temperature: 60°C Operating method: One-pass method Note that water was not replenished to the polar liquid during one experiment, and a large amount of liquid was circulated so that the concentration would not change significantly before and after the experiment.

The required power is expressed as the value obtained by multiplying the average electrolysis voltage (volts) by the amount of current (ampere-hours) divided by the weight of the ion-exchanged amino acids (kilowatt-hours/units).

The following method is used to express the degree of decomposition of amino acid salts and supporting salts.

a - Alkali ion equivalent in stock solution b = Alkali ion equivalent in ion exchange solution C - Amino acid salt equivalent in stock solution Ion exchange amount (d) = a - b Ion exchange rate above 100d/a (%) Amino acid conversion rate =100-d/c (%) Therefore,
When a portion of the supporting salt is decomposed, the amino acid conversion rate exceeds 100%.

In addition, the value obtained using the following formula is used for the current efficiency.

Current efficiency -2680d/Amount of current (%) Leprosy example I DL-α-alanine salt was added to 18.7. !
Various salts were added to an aqueous solution containing a ratio of i'/100 rul and electrolytic ion exchange was performed, and the results shown in Table 1 were obtained.

Of these, Experiment No. 1 is the result when no supporting salt was added, and is included for comparison.

Experiment No. 5 shows the case of partial electrolysis using the sodium salt of α-alanine itself as a supporting salt.

In this case, the pH value of the ion exchange solution is higher than in other cases.

The pH value varies depending on the temperature, but here it is all 50-6.
Measured values are shown at 0°C.

When a supporting salt is added, the electrolytic power is approximately 0% in both cases.
It's getting less.

Note that there is not much difference in current efficiency depending on whether or not a supporting salt is added, but this is because only one small electrolytic cell is used in this actual case, so there is almost no local unevenness in flow rate.

500ml each of ion exchange solution obtained by electrolysis
The amount of α-alanine crystals obtained by concentrating to 0 ml, cooling to 25° C., filtration, and washing with 25 to 100 ml of water is also shown in the table.

All of these had a quality that passed food additive standards.

Note that the low yield of α-ala**nine crystals in Experiment No. 5 is due to the low amino acid conversion rate and does not mean loss of α-alanine.

Unconverted α-alanine salt is recovered by reusing the mother liquor.

Example 2 The mother liquor and washing solution obtained in Experiment No. 3 of Example 1 were combined, and the sodium salt of α-alanine was added at 18.79%.
After adding it to 500 TL of an aqueous solution containing 7,100 ml, it was concentrated to a total volume of 500 ml, and this was subjected to electrolytic ion exchange.

The pH value of the ion exchange solution is 6.5, and the ion exchange rate is 94.
3%, amino acid conversion rate is 99.4%, electrolysis voltage is 6.8
The volt and current efficiency was 83.6%, and the electrolytic power was 2.45 kilowatt hours/kg.

Concentrate the total volume of this ion exchange solution to 150ml,
After cooling to 25℃, methanol 150ml! was gradually added, the precipitated α-alanine crystals were passed through, and methanol 1
Wash with 00rrLl and dry to obtain α-alanine crystals 96
．． 7g was obtained.

The total yield including the yield in Example 1 was 95.3%.

In addition, in calculating the amino acid conversion rate, imino-di-
It was assumed that propionic acid remained as a monosodium salt and sulfuric acid remained as a disodium salt.

In addition, when the amount of α-alanine transferred to the catholyte during electrolysis and the amount of α-alanine dissolved in the mother liquor was determined by analysis of the combined solution and added, the yield was almost 100%.
There was no loss due to degradation of alanine.

Example 3 3.65 g71.00T of sodium salt of methionine
Table 2 shows the results when electrolytic ion exchange was performed on an aqueous solution containing 100 ml and an aqueous solution to which sodium acetate was added as a supporting salt at a ratio of 0.75 g/100 rr Ll.

However, the current density was 0.10 ampere/crA.

Also, 5. Concentrate the ion exchange solution 5007711. O
After cooling to 25°C, filtering and washing with water, methionine crystals were obtained.

It can be seen that the method of the present invention with the addition of a supporting salt requires approximately 0% less electrolysis voltage despite a higher amino acid conversion rate.

Next, the entire amount of the mother liquor obtained from the experiment in which sodium acetate was added was added to the methionine sodium salt solution 5007.
711 to make a stock solution, which was subjected to electrolytic ion exchange and crystallization.

The results are shown in the rightmost column of Table 2.

It can be seen that methionine and sodium acetate in the mother liquor are effectively recovered and reused.

Example 4 Two electrolytic cells A and B were electrically connected in series, and potassium salt of β-alanine was added at 2 i, 6 g/1001 rL.
Electrolytic ion exchange is carried out while supplying an aqueous solution containing 1.0 mA/h to cell A at a flow rate of 360 mA/h and to cell B at a flow rate of 300 m1/h, and the pH value of the combined ion exchange solution that exits the two cells. An attempt was made to adjust the amount of current so that the pH was in the range of 7 to 8, but since the voltage of each cell was kept within a range of no more than 12 volts, the pH value only dropped to 8.4.

Next, 1.7 g of potassium acetate was added to the feed solution as a supporting salt.
A similar experiment was conducted by adding the following: /1,007,711.

Furthermore, electrolysis was carried out by supplying the solution with and without the supporting salt to two cells at an equal rate of 330 ml/hour.

The results of the above experiments are summarized in Table 3.

However, the voltage is the sum of the voltages of the two cells.

It can be seen that when no supporting salt is added, the voltage increases significantly due to the unevenness of the flow rates, a high amino acid conversion rate cannot be obtained, and the current efficiency also decreases.

On the other hand, in a solution containing a supporting salt, even if there is an uneven flow rate, the voltage does not increase much and the current efficiency does not decrease, and a high amino acid conversion rate can be obtained.

[Brief explanation of drawings]

FIG. 1 is a conceptual flow diagram of the amino acid production process to which the present invention is applied. FIG. 2 is a conceptual diagram of the structure of a unit cell of a royal method ion exchange membrane electrolyzer used for electrolytic ion exchange according to the present invention. In the figure, 1 is a raw material tank, 2 is a stock solution tank, 3 is an electrolytic device, 4 is a concentrator, 5 is a crystallization separation device, 6 is a second concentration device, 7 is a second crystallization separation device, 31 is an anode, 32 is an anode chamber, 33 is a cathode, 34 is a cathode chamber, 35a and 35c
is a cation permselective membrane, A is an anolyte, B is an ion exchange solution, C is a catholyte, and F is a stock solution.

Claims (1)

[Scope of Claims] 1. A method for producing an amino acid from an alkali metal salt of an amino acid, characterized by the following steps (1), (2), and (3). (1) Add one or more types of alkali metal salts (hereinafter referred to as supporting salts) of an acid as strong as or stronger than the amino acid to an aqueous solution containing an alkali metal salt of a neutral amino acid at a concentration of 0.03 to 1
Add at a ratio of equivalent/l to obtain a stock solution. (2) While circulating an aqueous solution of an inorganic acid in the anode chamber of an electrolytic device in which two cation selectively permeable membranes are provided as a diaphragm between the two electrodes, and distributing an aqueous solution of alkali hydroxide in the cathode chamber,
By passing the above stock solution through an ion exchange chamber sandwiched between two cation-selective membranes and performing electrolytic ion exchange, alkali hydroxide is obtained in the catholyte, and at the same time, the effluent from the ion exchange chamber ( A mixed solution of an amino acid and a supporting salt is obtained as an ion exchange solution (hereinafter referred to as an ion exchange solution). (3) After the ion exchange solution is concentrated as it is or as appropriate, it is cooled or alcohol is added to precipitate crystals of the amino acid, and the crystals are separated in a furnace to obtain the amino acid.