JPH03279352A - Method for removing cyanogen in amino acid solution - Google Patents

Abstract

PURPOSE:To enable selective removal of cyanogen in an amino acid solution and complete adsorption and removal thereof to the detection limit or below and effectively reuse an adsorbent by using a resin containing group VIII, Ib or IIb metal ions adsorbed on a pyridine-based polymer as the adsorbent. CONSTITUTION:A cyanide is removed from an amino acid solution containing the cyanide, especially from an amino acid solution prepared by the Strecker method. In the process, a resin obtained by adsorbing group VIII, Ib or IIb metal ions on a pyridine-based polymer is used as an adsorbent to adsorb and remove cyanogen. Thereby, the cyanogen concentration can be reduced to <=0.05mg/l. The used adsorbent can be advantageously reused by regeneration treatment.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for removing cyanide from an amino acid solution,
In particular, it relates to a method for removing cyanide from an amino acid solution obtained by the Strecker method.

Demand for amino acids has increased in recent years, and they are widely used in infusions, seasonings, health foods, nutrients, feed additives, and as raw materials for industrial chemicals. There are many important amino acids.

[Prior Art 1 Many conventional methods for treating cyanide-containing waste liquid have been known for a long time.

That is, the hydrolysis method using an alkali (for example, JP-A No. 4
4-25185), a method of forming a complex salt with copper chloride or the like and separating it by precipitation (e.g., JP-A-43-13288), a decomposition method using chlorine gas (e.g., JP-A-39-70)
46), a method of changing to cyanic acid (for example, JP-A No. 46),
4-10197), a method of forming a complex with iron ions and separating by precipitation (for example, JP-A-45-1730)
, a decomposition method using sodium subzinc chloride (for example, JP-A-45
29790), activated carbon adsorption method, hypo method, etc.

However, our work with amino acid solutions shows that most of these methods cannot completely remove cyanide in amino acid solutions below the detection limit of 0.0511 g, # without damaging the amino acids. could not. In addition, among these methods, the method of adding copper ions to form a complex salt removes free cyanide ions to 0.
．． Although it was possible to reduce the amount to less than 0.05 mg #, post-treatment of the toxic complex salt is a problem, which is technically difficult.

As a known technique for treating cyanide in an amino acid solution, there is a method in which carbon dioxide gas is blown into an N-phenylglycine alkaline solution obtained by the Strecker reaction and the remaining cyanide alkali salt is discharged from the system (Japanese Patent Laid-Open No. 59
210052), but although this method could reduce cyan to 5 pp+m or less, it could not completely remove it below the detection limit.

[Problems to be Solved by the Invention] When producing amino acids from aldehydes or ketones, cyanide, ammonia, etc. by the Strecker method, a method for removing residual cyanide becomes a major problem.

After the Strecker reaction, cyanide is typically removed from the synthetic amino acid solution by heating in the presence of excess ammonia to convert the alkali cyanide to alkali hydroxide. However, in reality, cyanide often remains on the order of ppm, and removal of highly toxic cyanide is often insufficient.

The coexistence of amino acids in a solution is considered to be an unfavorable condition for the removal of cyanide, and it is not possible to completely remove cyanide from an amino acid solution by a simple method using the above-mentioned known techniques without damaging the amino acids. Ta.

[Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present inventors found a specific adsorbent, and by bringing a liquid containing amino acids and cyanide into contact with this adsorbent, , selectively removes only cyan, reducing the cyan concentration to 0.05mg/j
We were able to achieve the following (below the detection limit) and achieved the intended purpose.

That is, the present invention provides a method for adsorbing and removing cyanide from an amino acid beach solution containing cyanide, in which a pyridine-based polymer adsorbed with group (I), Ib, or IIb metal ions is used as an adsorbent. This is a characteristic method for removing cyanide from an amino acid solution.

[Detailed Description of the Invention 1 fi + Adsorbent The adsorbent used in the present invention is a pyridine polymer containing
It is a resin on which group Ib or group IIb metal ions are adsorbed.

In addition to poly-4-vinyl and lysine, examples of the pyridine-based polymer include, but are not limited to, vinyl alcohol, a copolymer of vinyl halide and 4-vinylpyridine, and the like.

The metal ions to be immobilized on these pyridine polymers are Group I, Group Ib, or Group IIb metal ions, and among these, nickel ions, cobalt ions, iron ions, platinum ions, and palladium ions are preferred.

In order to fix metal ions on a pyridine-based polymer, the pyridine-based polymer is suspended in an organic compound commonly used as a reaction solvent such as methanol, dioxane, dimethylpolamide, or methyl sulfoxide, water, or a mixture of the organic compound and water. Fix the metal ions to the pyridine polymer by adding salts of the metal ions 1, such as nitrates, sulfates, chlorides, etc., at room temperature or in a heated state, and stirring slowly for several minutes to several hours. can be converted into They can also be made by other known methods of preparing metal-containing polymers.

(2) Removal of cyanide By bringing the above adsorbent into contact with an amino acid and a cyanide-containing liquid for an appropriate period of time, only cyanide can be completely adsorbed and removed. In this case, the amino acids are
Amino acids that can be synthesized by the Strecker reaction may include alanine, gutsine, methionine, threonine, serine, etc. However, the applicable amino acids are not limited to these.

The liquid to be brought into contact is usually an aqueous solution, but it may also contain organic substances such as alcohols such as ethylene glycol that do not have an adverse effect on the amino acids. Salts such as ammonium chloride and sodium chloride, which are preferable for maintaining shape,
Alkali such as ammonia and sodium hydroxide, acids such as sulfuric acid, etc. may be contained in appropriate proportions. However, acids may slightly decompose amino acids and may cause metal ions to be detached from the polymer. Therefore, it is better not to make the pn of the liquid strongly acidic.

The amino acid in the liquid to be contacted may be in an anionic state such as a sodium salt or in a non-dissociated state.Differences in these states will not impair the separation of the amino acid and cyanide.Cyanide in the liquid to be contacted may also be in an anionic state. It can be in the state or in the non-dissociated state A.

The amino acid concentration of the liquid to be contacted is preferably about 100 g/j or less.The cyanide concentration before contact is too high from the viewpoint of reducing the required amount of adsorbent or adsorption efficiency.
It is preferably less than 100 ppm, particularly preferably less than 100 ppm.

Contact between the adsorbent and the liquid may be carried out by either a batch method or a packed bed flow method, but the flow method is easier to operate.

In the case of the packed bed flow system, the total amount of liquid that can be treated with respect to the amount of adsorbent packed is determined by the cyanide concentration in the liquid, the type of metal on the adsorbent, and the amount of metal ions supported. Since one or more CN- groups can be selectively adsorbed per metal ion fixed on the adsorbent, until the total equivalent of cyanide flowing into the adsorbent reaches the equivalent of the metal ion in the adsorbent,
Cyan can be removed reliably.

The treatment may be carried out at around room temperature or in a heated state of about 100° C. or less; care must be taken because if the temperature is too high, the amino acids may decompose.

The contact time between the present adsorbent and the liquid depends on the temperature and the type of adsorbent, so it cannot be absolutely specified, but it is about several minutes to several hours.

(3) Desorption and regeneration When the adsorbent approaches cyanide adsorption saturation, the metal ions and cyanide are desorbed from the polymer using an acid such as sulfuric acid, and the metal ions are immobilized on the polymer again using a metal sulfate. can be played.

The desorbed complex salt of metal ions and cyanide can be easily rendered harmless by treatment with an alkali, concentration, incineration, or the like.

〔Example〕 The present invention will be explained in more detail with reference to Examples below.

In addition, high performance liquid chromatography was used to analyze serine in the liquid, and analysis of cyan was performed according to JIS KO10238, l.
and 38.3, according to the factory wastewater test method.

Example 1 Approximately 1:1 copolymer of vinyl chloride and 4-vinylpyridine H4CH, -CH-CH2-CH←H py cR (EX-212, Lot No. 310, manufactured by Kyoei Kagaku ■)
12, granular) 15.0g, 6.0g of N1fNOih
- Added 6H20 to an aqueous solution of 180 mj of water and slowly stirred at about 60°C for about 3 hours. The colored resin was filtered, washed with water, and dried at room temperature to obtain 16.65 g of nickel-immobilized KEX-212.

6.2 g of the above nickel-immobilized KEX-212 was added to a 40° Ilj aqueous solution of DL-serine (manufactured by Ajinomoto Co., Ltd., concentration 20 g/j) and sodium cyanide (fcN-group 1100 I/j), and the mixture was heated at 60°C for 30° C. After stirring slowly for a minute, filter.

Add new nickel-immobilized KEX-212 to the filtrate again.
was added, slowly stirred for 30 minutes at the same <60°C, and filtered. 100% of the serine in the filtrate was recovered. (below), no leakage of nickel ions into the filtrate was observed.

Example 2 Poly-4-vinylpyridine H2CO, -CH+-Hpy (P-4VP manufactured by Guangsong Chemical Company: Lot No. 20317
, irregular shape) 16.0 g, 49 g of N1fNO-1
About 37% by weight methanol water droplet solution of z・6H20 120■
It was added to the aqueous solution added in 1 and slowly stirred at about 80°C for 20 minutes. The colored resin was filtered, washed with water, and dried at room temperature to obtain 17.4 g of nickel-immobilized P-4VP.

The above nickel-immobilized P-4VP was added to 400 mj of an aqueous solution of DL-serine (manufactured by Ajinomoto Co., Ltd., concentration 20 g) and sodium cyanide (fcN-group 100 mg/j).
After adding 2g and stirring slowly at 60°C for 30 minutes, it was filtered, and fresh nickel-immobilized P-4V was added to the filtrate again.
4.2 g of P was added, slowly stirred for 30 minutes at the same <60°C, and filtered.

Serine in the filtrate was 100% recovered. C in filtrate
The amount of N-groups was 0.05 g/j or less (below the detection limit), and no leakage of nickel ions into the filtrate was observed.

Example 3 Glycolaldehyde 6.48g fl 8 mmol)
To an aqueous solution of about 341j added to water, 4.71 g (96 mmol) of sodium cyanide, 6.42 g (120 mmol) of ammonium chloride) and 23.5 g (345 mmol as NHs) of 25% by weight aqueous ammonia were added.
After the Strecker reaction was carried out at 45°C for 1 hour, an aqueous solution of sodium hydroxide (10.58 F264 mmol) dissolved in 3 ml of water (Ig) was added, and the mixture was heated at 80°C.
A hydrolysis reaction was carried out for 4 hours to synthesize sodium serine salt.

The resulting 50 mj aqueous solution contained 10.0 g (78.9 mmol) of serine sodium salt, about 7.2 g of sodium chloride, and about 3.0 g of sodium hydroxide.

The yield of serine sodium salt based on sodium cyanide was 82.3%.

Ammonia was distilled off from this reaction solution under a reduced pressure of 30-30-100 at 45-60°C. Next, the pH was adjusted with 10% sulfuric acid to obtain an aqueous solution with a serine isoelectric point pH = 5.70. .

A glass column with an inner diameter of 3G+m was filled with Na-type strongly acidic cation exchange resin Diaion 5K-IBS (manufactured by Mitsubishi Kasei) 12 μm, washed with a small amount of water, and heated 60°C water was circulated through the column jacket. After warming for a while, the above pH 5.7 solution was introduced from the top of the column at 5V=0.4/hr, and serine was fractionated using a refractive index detector. After the inorganic salt had flowed out, serine began to flow out, and about 300 mg of the effluent during this period was obtained.

The serine concentration of this serine effluent is 26.5 g/j, CN
The concentration of - group was 120 mg 7 g.

To this serine effluent was added 7.5 g of nickel-immobilized KEX-212, which was exactly the same as in Example 1, and after stirring slowly at 60°C for 30 minutes, it was filtered. 212 was added thereto, and the mixture was slowly stirred at 60° C. for 30 minutes, and then filtered. 100% of serine in the filtrate was recovered.

The amount of CN- groups in the filtrate was less than 0.05+++g, # (below the detection limit), and no leakage of nickel ions into the filtrate was observed.

[Effects of the Invention] By using a pyridine-based polymer that adsorbs and immobilizes specific metal ions as an adsorbent, cyanide can be selectively and completely adsorbed and removed below the detection limit. can be reused by recycling.

Claims (3)

[Claims] (1) A method for adsorbing and removing cyanide from a cyanide-containing amino acid solution, characterized by using a pyridine-based polymer adsorbing Group VIII, Group Ib, or Group IIb metal ions as an adsorbent. Method for removing cyanide from amino acid solution. (2) The method according to claim 1, wherein the amino acid solution is an amino acid solution synthesized by the Strecker method using an aldehyde or ketone and cyanide, or a solution obtained by processing the amino acid solution. (3) The method according to claim 1 or 2, wherein the amino acid is serine.