JP5927912B2 - Method for recovering noble metal from solution containing noble metal ions, back extractant and desorbent used therefor - Google Patents

Description

  The present invention relates to a method of recovering a noble metal by reducing a solution containing a noble metal ion extracted or adsorbed by an extractant or adsorbent and then back-extracted or desorbed by a back-extractant or desorbent, and a reverse used for the same. The present invention relates to an extractant and a desorbent.

  Industrial catalysts, automobile exhaust gas purification catalysts and many electrical appliances use noble metals such as palladium, platinum and rhodium. Since noble metals are expensive and useful as resources, they are conventionally collected and recycled after use. In recent years, the demand for resource conservation has increased, and the importance of recovery and recycling of precious metals has increased.

  As a method for recovering the noble metal, methods such as a precipitation separation method, an ion exchange method, an electrolytic deposition method, and a solvent extraction method have been developed. When the noble metal is palladium ion, the solvent extraction method among the above methods is widely adopted from the viewpoints of economy and operability.

  As a method for recovering palladium ions by a solvent extraction method, for example, an extraction step of extracting palladium ions to the organic phase side by bringing the aqueous phase in which palladium ions are dissolved into contact with the organic phase in which the oil-soluble extractant is dissolved is liquid-liquid contact. And a back extraction step of back extracting the palladium ions extracted on the organic phase side back to the aqueous phase side again using the aqueous phase in which the back extractant is dissolved. More specifically, palladium ions are back-extracted by an organic phase using a dialkyl sulfide compound as an extractant, and palladium is back-extracted by an aqueous phase using ammonia water as a back extractant (for example, , See Patent Document 1).

  In order to improve the extraction speed in the solvent extraction method, an extractant with an amide group introduced near the sulfur of the dialkyl sulfide has been proposed, and a palladium recovery method using an acidic thiourea aqueous solution as the back extractant has been proposed. (For example, refer to Patent Document 2).

  However, since the above-described solvent extraction method uses a large amount of organic solvent, it has problems in terms of safety and environmental load.

  For this reason, a palladium ion adsorption method has been proposed as a recovery method that does not use an organic solvent (see, for example, Patent Document 3). In this method, an adsorbent is prepared by immobilizing a specific sulfide compound on a styrene derivative polymer (eg, polychloromethylstyrene) carrier as a ligand (acceptor) of palladium ion, and this adsorbent is dissolved in palladium ion. The palladium ions are adsorbed by adding them directly to the aqueous solution.

  In addition, the present applicant has already filed a patent application regarding an adsorbent using a compound in which an amide group is introduced in the vicinity of sulfur of a dialkyl sulfide as a ligand of palladium ion (see, for example, Patent Documents 4 and 5).

  When an extractant or adsorbent containing an amide group in the vicinity of sulfur in the dialkyl sulfide is used, if hydrochloric acid or ammonia is used as the back extractant or desorbent, the reverse extraction or desorption rate of palladium ions is low. An aqueous urea solution is preferably used (see, for example, Patent Document 5).

Japanese Patent Laid-Open No. 9-279264 International Publication No. 2005/083131 Pamphlet JP-A-5-105973 JP 2011-41916 A JP 2011-41918 A

  In accordance with Patent Documents 4 and 5, the present inventors prepared an adsorbent in which an amide group-introduced compound (ligand) was immobilized on an alumina carrier in the vicinity of sulfur of a dialkyl sulfide, adsorbed palladium ions in an aqueous solution, Next, palladium ions were desorbed using an aqueous thiourea solution to obtain a solution containing palladium ions. In order to recover metallic palladium from the obtained solution, an electrolytic reduction of the recovered liquid was attempted. As a result, the obtained metallic palladium was of low purity containing a large amount of sulfur-containing impurities. In order to obtain high-purity metal palladium from this low-purity metal palladium, it has been found that a complicated high-purity treatment is required.

  Thus, the present invention has been made in view of the above circumstances, and the object thereof is to obtain a noble metal obtained by efficiently back-extracting or desorbing a noble metal ion, particularly palladium ion, extracted or adsorbed on an extractant or an adsorbent. A back extractant or desorbent that makes it possible to obtain a high-purity precious metal by reducing a solution containing ions (hereinafter also referred to as a recovered solution), and recovery of the precious metal using the back extractant or desorbent. It is to provide a method.

  As a result of intensive studies to solve the above problems, the present inventors have found that the sulfur-containing amino acid derivative represented by the general formula (1) is superior in noble metal ions as compared with conventionally known hydrochloric acid, ammonia and the like. It was found that it exhibits reverse extractability and desorption properties. Furthermore, unexpectedly, when the recovered solution obtained by back extraction or desorption using such a sulfur-containing amino acid derivative is reduced, the purity is extremely high compared to the case of using conventional thiourea. The inventors have found that noble metals can be easily obtained, and have completed the present invention.

  That is, the present invention has the following gist.

[1]
General formula (1)

(Wherein R ¹ represents a methyl group, an ethyl group, a vinyl group, a linear, branched, or cyclic hydrocarbon group having 3 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms; ² are each independently a hydrogen atom, a methyl group, an ethyl group, a vinyl group, a linear, branched, or cyclic hydrocarbon group having 3 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms. And n represents 0 or 1.)
A noble metal ion back extractant or desorbent comprising a sulfur-containing amino acid derivative represented by:

[2]
In the sulfur-containing amino acid derivative represented by the general formula (1) according to [1], R ¹ is a methyl group, and each R ² is independently a hydrogen atom, a methyl group, an ethyl group, a vinyl group, carbon Noble metal ion back-extracting agent or desorption, which is a linear, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms or an aromatic hydrocarbon group having 6 to 14 carbon atoms and n is 1 Agent.

[3]
A sulfur-containing amino acid derivative represented by the general formula (1) according to [1] is a methionine, a noble metal ion back extractant or desorbent.

[4]
A solution containing a noble metal ion obtained by bringing the noble metal ion back-extracting agent or desorbing agent according to any one of [1] to [3] into contact with an extracting agent or an adsorbing agent containing noble metal ions is reduced. A method for recovering precious metals, characterized by obtaining precious metals by processing.

[5]
The method according to [4], wherein the noble metal ion is palladium ion and the noble metal is palladium.

[6]
A solution containing noble metal ions is obtained by bringing the noble metal ion back-extracting agent or desorbing agent according to any one of [1] to [3] into contact with an extracting agent or adsorbing agent containing noble metal ions. A back extraction method or desorption method for precious metal ions.

[7]
[1] A method for producing a noble metal, comprising reducing a solution containing a noble metal ion back-extracting agent or desorbing agent according to any one of [1] to [3] and a noble metal ion.

[8]
The following general formula (1)

(Wherein R ¹ represents a methyl group, an ethyl group, a vinyl group, a linear, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms; R ² Each independently represents a hydrogen atom, a methyl group, an ethyl group, a vinyl group, a linear, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms, n represents 0 or 1.)
A noble metal ion desorbing agent comprising a sulfur-containing amino acid derivative represented by:

[9]
The noble metal ion desorbing agent according to [8], wherein the sulfur-containing amino acid derivative is methionine.

[10]
A method for desorbing a noble metal ion, wherein the noble metal ion desorbing agent according to [8] or [9] is brought into contact with an adsorbent adsorbing the noble metal ion to desorb the noble metal ion.

[11]
[10] A method for recovering a noble metal, wherein the aqueous solution containing the noble metal ion obtained by the method for desorbing a noble metal ion according to [10] is subjected to reduction treatment to precipitate and recover the noble metal.

[12]
The method for recovering a noble metal according to [11], wherein the noble metal ion is palladium ion and the noble metal is palladium.

  According to the present invention, by using the sulfur-containing amino acid derivative represented by the general formula (1), the extracted or adsorbed noble metal ion, particularly palladium ion, is efficiently back-extracted or desorbed, and the recovered liquid obtained By this reduction treatment, a high-purity noble metal, particularly metallic palladium, which has a significantly lower content of impurities such as sulfur than conventional ones, can be easily obtained.

  Hereinafter, the present invention will be described in detail.

(Back extractor or desorbent)
In the sulfur-containing amino acid derivative represented by the general formula (1) contained in the back extractant or desorbent of the present invention, R ¹ is a methyl group, an ethyl group, a vinyl group, 3 to 8 carbon atoms, preferably carbon. Represents a linear, branched or cyclic hydrocarbon group having 3 to 6 carbon atoms, or an aromatic hydrocarbon group having 6 to 14 carbon atoms, preferably 6 to 10 carbon atoms, and each R ² independently represents a hydrogen atom, A methyl group, an ethyl group, a vinyl group, a C3-C8 linear, branched or cyclic hydrocarbon group, or a C6-C14 aromatic hydrocarbon group is represented, and n represents 0 or 1.

  The linear, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms is not particularly limited. For example, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, isopropyl group, Isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, tert-pentyl group, 2-ethylhexyl group, allyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group 2-methylallyl group, 1-heptynyl group, 1-hexenyl group, 1-heptenyl group, 1-octenyl group, 2-methyl-1-propenyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl Group, cyclooctyl group, cyclohexenyl group, cyclohexadienyl group, cyclohexane Satorieniru group, cyclooctenyl group, cyclooctadienyl group and the like.

  Examples of the aromatic hydrocarbon group having 6 to 14 carbon atoms include, but are not limited to, phenyl group, naphthyl group, anthryl group, tolyl group, xylyl group, cumenyl group, benzyl group, phenethyl group, and styryl group. , Cinnamyl group, biphenyl group, phenanthryl group and the like.

Among these, R ¹ is preferably a methyl group or an ethyl group, and R ² is independently preferably a hydrogen atom, a methyl group or an ethyl group, from the viewpoint of noble metal ions, particularly preferably palladium ion back-extractability or desorption. Among these, methionine, in which R ¹ is a methyl group, all R ² are hydrogen atoms, and n = 1, is particularly preferable from the viewpoint of noble metal ion back-extraction or desorption and availability.

  In the case of methionine among the sulfur-containing amino acid derivatives represented by the general formula (1), production examples thereof are shown below.

  Methyl mercaptan and acrolein are reacted to produce 3-methylmercaptopropionaldehyde, which is then cyanohydrinized with hydrocyanic acid to give 3-methylmercaptopropion cyanohydrin. M-hydantoin is obtained by hydantoinizing the obtained 3-methylmercaptopropion cyanohydrin with carbon dioxide and ammonia.

  The obtained M-hydantoin includes alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal carbonates such as sodium carbonate and potassium carbonate, and alkali metal hydrogen carbonates such as sodium bicarbonate and potassium bicarbonate. Hydrolysis in the presence of alkali gives the alkali metal salt of methionine. The obtained alkali metal salt of methionine is neutralized by adding sulfuric acid, hydrochloric acid, carbon dioxide or the like to crystallize methionine. The precipitated methionine can be obtained by filtration, separation, washing with water if necessary, and drying (see, for example, JP-A-2000-143617).

Of the sulfur-containing amino acid derivatives represented by the general formula (1), R ¹ is a methyl group, and each R ² is independently a hydrogen atom, a methyl group, an ethyl group, a vinyl group, or a carbon number of 3 to 8. A production example in the case of a methionine derivative which represents a linear, branched or cyclic hydrocarbon group or an aromatic hydrocarbon group having 6 to 14 carbon atoms and where n = 1 is shown.

  That is, methionine is N-alkylated (see, for example, Laboratory Science, 4th edition, Volume 20, Section 285) or N-arylation (eg, Tetrahedron Letters, 1998, using known reagents). 39, see page 2367) and / or esterification (see, for example, Experimental Chemistry Course, 5th Edition, Volume 16, Section 285) to produce a methionine derivative represented by general formula (1). I can do it.

Among the sulfur-containing amino acid derivatives represented by the general formula (1), R ¹ is a methyl group, an ethyl group, a vinyl group, a straight chain, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms, or 6 to 6 carbon atoms. Each of R ² independently represents a hydrogen atom, a methyl group, an ethyl group, a vinyl group, a linear, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms, or a carbon number; The production example in the case of the sulfur-containing amino acid derivative which represents the aromatic hydrocarbon group of 6-14 and is n = 1 is shown.

  That is, instead of methyl mercaptan in the production method described in JP-A-2000-143617, the following general formula (2)

(Wherein R ¹ is the same as R ¹ in the general formula (1).)
Is used to obtain S-substituted-2-amino-4-mercaptobutyric acid. The obtained S-substituted-2-amino-4-mercaptobutyric acid is N-alkylated (for example, see the above-mentioned literature) or N-arylation (for example, see the above-mentioned literature) and / or using a known reagent. By esterification (for example, refer to the above-mentioned document), a methionine derivative represented by the general formula (1) where n = 1 can be arbitrarily produced.

Among the sulfur-containing amino acid derivatives represented by the general formula (1), R ¹ is a methyl group, an ethyl group, a vinyl group, a straight chain, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms, or 6 to 6 carbon atoms. Each of R ² independently represents a hydrogen atom, a methyl group, an ethyl group, a vinyl group, a linear, branched or cyclic hydrocarbon group having 3 to 8 carbon atoms, or a carbon number of 6; The example of manufacture in the case of the sulfur-containing amino acid derivative which represents -14 aromatic hydrocarbon group and is n = 0 is shown.

  That is, cysteine is converted to S-alkylation using a known reagent (see, for example, New Experimental Chemistry Course, Vol. 16, Section 1716), N-alkylation (see, for example, the above-mentioned literature) or N-arylation ( For example, the sulfur-containing amino acid derivative represented by the general formula (1) where n = 0 can be arbitrarily produced by esterification (for example, see the above-mentioned literature) and / or esterification.

  The sulfur-containing amino acid derivative represented by the general formula (1) has an asymmetric center, but may be any of S-form, R-form, or racemic mixture. The sulfur-containing amino acid derivative is not particularly limited, and may be a salt such as hydrochloride, nitrate, sulfate, lithium salt, sodium salt, potassium salt, cesium salt and the like.

(Back extraction method or desorption method with back extractant or desorbent)
The sulfur-containing amino acid derivative represented by the above general formula (1) is used as a back extractant or a desorbent, and the precious metal ions are back-extracted or brought into contact with an extractant or adsorbent containing precious metal ions, respectively. Can be desorbed.

  As the back extractant or desorbent containing the sulfur-containing amino acid derivative represented by the general formula (1) (hereinafter also referred to as “back extractant or desorbent of the present invention”), an aqueous solution of such a sulfur-containing amino acid derivative is used. Preferably, the concentration of the sulfur-containing amino acid derivative in the aqueous solution is not particularly limited, but is usually 0.1 to 20% by weight. The back extractant or desorbent may contain salts such as sodium chloride, organic solvents such as methanol, polymers such as polysaccharides, and other third components.

  The back extractant or desorbent of the present invention can be used without any problem in basic, neutral, and acidic liquids, but an acidic aqueous solution is usually used in a noble metal extraction process and an adsorption process. It is preferably used under acidic conditions.

  The acid used in the acidic aqueous solution of the back extractant or desorbent of the present invention is not particularly limited, but inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid are preferred, and among these, hydrochloric acid is particularly preferred. Although it does not specifically limit as acid concentration of this acidic aqueous solution, The range of 0.01-10 mol / L is preferable and 0.1-5 mol / L is more preferable. In particular, when the acid concentration is 1 to 3 mol / L, it is possible to quantitatively back-extract or desorb noble metal ions, and chemical damage of the extractant or adsorbent, and the noble metal ion ligand from the adsorbent. This is preferable because desorption can be reduced.

  In the back extraction or desorption using the back extractant or desorbent of the present invention, the target noble metal ion is not particularly limited. For example, palladium ion, platinum ion, gold ion, rhodium ion, iridium ion, Examples thereof include noble metal ions having high affinity for sulfur atoms such as ruthenium ions and osmium ions. Among these, palladium ions are particularly preferable, and the palladium ions may coexist with the other noble metal ions described above.

  In the back extraction or desorption using the back extractant or desorbent of the present invention, the amount of the back extractant or desorbent used is not particularly limited, but the sulfur-containing amino acid derivative is used with respect to 1 mol of the target noble metal ion. It is preferable to adjust so that it may become 2 times mole amount or more, and it is more preferable to adjust so that it may become 5-1000 times mole.

  Such back extraction or desorption is usually carried out under normal pressure or in the atmosphere, but can also be carried out under pressure or under reduced pressure, or in the presence of an inert gas. Such back extraction or desorption is usually carried out in a temperature range of 4 to 150 ° C, but a temperature range of 10 to 50 ° C is more preferable.

  In such back extraction or desorption, other back extraction agents or desorption agents other than the sulfur-containing amino acid derivative represented by the general formula (1) can be used in combination as long as the object of the present invention is not impaired.

  By such back extraction or desorption, a solution containing the sulfur-containing amino acid derivative represented by the general formula (1) and a noble metal ion is obtained.

(Recovery of precious metals by reduction treatment)
A solution containing noble metal ions, particularly palladium ions, preferably back-extracted or desorbed by the back-extracting agent or desorbing agent of the present invention (hereinafter also referred to as a solution for reduction treatment) is reduced as it is or after neutralization. By the treatment, a noble metal, particularly metal palladium can be obtained.

  The reduction treatment solution is preferably an aqueous solution. The aqueous solution may contain a component derived from the back extractant or desorbent of the present invention. That is, it may contain salts such as sodium chloride, organic solvents such as methanol, polymers such as polysaccharides, and other third components.

  Such reduction treatment can be carried out under any of acidic conditions, neutral conditions, and basic conditions, but the pH is 6 or more and 8 or less from the viewpoint of reducing the precious metal ion reduction efficiency and the corrosiveness of the equipment. Is preferred. When the solution for reduction treatment is acidic, it is preferable to neutralize in advance, and the neutralizing agent is not particularly limited, but for example, an inorganic base compound such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, or slaked lime is used. It can be preferably used.

  Although it does not specifically limit as a density | concentration of the sulfur-containing amino acid derivative represented by General formula (1) contained in the solution for a reduction process, For example, it is 0.01 to 30 weight% preferable. Among these, it is more preferable that it is 0.01 to 15 weight% from an economic point of view.

  The concentration of the noble metal ions in the reduction treatment solution is not particularly limited, but is preferably 0.01% by weight or more and 20% by weight or less. Among these, it is more preferable that it is 0.01 weight% or more and 15 weight% or less at the point of the ease of handling.

  The reduction treatment of the present invention is not particularly limited, but various methods can be used depending on the purpose and equipment. For example, electroreduction by electrolysis or a reducing agent such as hydrogen gas or boron hydride compound can be used. The chemical reduction method to add is mentioned. Among these, the electrolytic reduction method is preferable from the viewpoint of ease of operation and cost.

When such a reduction treatment is performed by an electrolytic reduction method, for example, a known electrolytic reduction treatment described in “Electrochemical reaction operation and electrolytic cell engineering” (published by Kagaku Dojin Co., Ltd., 1979, page 175) can be used. . For example, a titanium electrode whose surface is coated with platinum is used as the anode, and a titanium electrode, a copper electrode, a nickel electrode, or the like is used as the cathode. The current density is preferably 0.001 to 100 A / dm ² , and particularly preferably 1 to 50 A / dm ² .

  Although the noble metal can be obtained by the reduction treatment of the present invention, the noble metal is obtained as a noble metal precipitate. The noble metal precipitate can be separated from the back-extracting agent or desorbing agent or water by filtration. Examples of the filtration method include a method using a membrane filter, filter paper, filter cloth, glass filter or the like, but a method using a membrane filter or filter paper is preferable from the viewpoint of ease of operation. Thus, the noble metal can be produced and isolated from the reduction treatment solution obtained by the above-described back extraction or desorption.

(Extraction or adsorption of noble metal ions from solutions containing noble metal ions)
In the back extraction or desorption of the noble metal ions using the back extractant or desorbent of the present invention, the extractant or adsorbent of the noble metal ions to be treated is not particularly limited, and various types can be mentioned.

  Although it does not specifically limit as an extracting agent, For example, the extracting agent containing a dihexyl sulfide, a dioctyl sulfide, etc. can be mentioned.

  Examples of the adsorbent include commercially available products such as the SiliacBond series manufactured by SILICYCLE and the QuadraPure series manufactured by Reaxa, or those in which a ligand that captures a conventionally known noble metal ion is supported on an appropriate carrier. The ligand that captures the noble metal ion is not particularly limited, but a compound having a sulfide group or an amino group is preferably used.

  The extractant is usually used as a solution in an organic solvent. The organic solvent is preferably not miscible with water and is not particularly limited. For example, tobenzene, ruene, xylene, hexane, methylene chloride, chloroform and the like can be used.

  The extractant extracts noble metal ions by contact with an aqueous solution in which the noble metal ions are dissolved. Then, the back extractant containing the sulfur-containing amino acid derivative represented by the general formula (1) is brought into contact with the extractant separated from the mother aqueous solution, so that the noble metal ion is taken from the phase of the extractant. Back extracted to the phase of Although it does not specifically limit in the contact and mutual separation of an extractant and a back extractant, For example, a separating funnel can be used. It is also possible to use an industrial apparatus having the same function as the separatory funnel.

  On the other hand, in the adsorbent in which the above-mentioned ligand for capturing noble metal ions is supported on a suitable carrier, the carrier can be used without particular limitation as long as it is insoluble in water. For example, styrene polymers such as polystyrene or crosslinked polystyrene, polyolefins such as polyethylene or polypropylene, poly (halogenated olefins) such as polyvinyl chloride or polytetrafluoroethylene, nitrile polymers such as polyacrylonitrile, polymethyl methacrylate, poly Synthetic high molecular weight carriers such as (meth) acrylic acid ester polymers such as ethyl methacrylate, natural high molecular weight carriers such as cellulose, agarose, dextran, or activated carbon, silica gel, diatomaceous earth, hydroxyapatite, alumina, titanium oxide, magnesia, poly An inorganic carrier such as siloxane may be mentioned.

  Cross-linked polystyrene means monovinyl aromatic compounds such as styrene, divinylbenzene, vinylxylene, vinylnaphthalene and polyvinylaromatic compounds such as divinylbenzene, divinyltoluene, divinylxylene, divinylnaphthalene, trivinylbenzene, bisvinyldiphenyl, bisbiphenylethane, etc. A cross-linked copolymer with a compound may be the main component, or a methacrylic acid ester such as glycerol methacrylate or ethylene glycol dimethacrylate may be copolymerized with these copolymers.

  Of these insoluble carriers, silica gel or alumina is preferable from the viewpoint of price and availability.

  The shape of the insoluble carrier is generally used as a separation substrate such as spherical (eg, spherical particles), granular, fibrous, granular, monolithic column, hollow fiber, membrane (eg, flat membrane), etc. The shape to be used can be used and is not particularly limited. Of these, spherical, membranous, granular and fibrous ones are preferred. The granular particles are particularly preferable because the volume of use can be arbitrarily set when used in the column method or batch method.

  As the particle size of the carrier, those having an outer diameter of 1 μm to 10 mm can be used, but those having a diameter of 2 μm to 1 mm are preferred from the viewpoint of precious metal ion adsorption performance and ease of handling. The support may be porous or nonporous, and can be used without any problem. However, a porous support is preferred because it has a wide effective area for precious metal ion adsorption.

  The method for immobilizing the ligand that captures the noble metal ion on the carrier is not particularly limited, and examples thereof include a method of physically adsorbing and supporting or a method of immobilization by chemical bonding.

  A commercially available noble metal ion adsorbent and a noble metal ion adsorbent in which an arbitrary ligand is immobilized on a carrier are not particularly limited. For example, the noble metal ion adsorbent can be used in a column method or a batch method. Can be used on floor or extended floor.

  The present invention will be specifically described below, but the present invention is not construed as being limited by these examples.

¹ H-NMR (nuclear magnetic resonance) was measured by Gemini-200 (manufactured by Varian).

  Metal ion aqueous solutions are commercially available palladium standard solution (1000 ppm), platinum standard solution (1000 ppm), rhodium standard solution (1000 ppm), copper standard solution (1000 ppm), iron standard solution (1000 ppm), nickel standard solution (1000 ppm), The zinc standard solution (1000 ppm) was diluted.

  The palladium ion concentration and the metal palladium purity in the aqueous solution were measured with an ICP emission spectroscopic analyzer (OPTIMA 3300 DV, manufactured by Perkin Elmaer).

  The sulfur content was measured by ion chromatography. Ion chromatography measurement was performed with the following pretreatment, equipment and conditions.

Pretreatment: The sample was introduced into an automatic sample combustion apparatus (AQF-100, manufactured by Mitsubishi Chemical Analytic Co., Ltd.), and SO ₄ ²⁻ produced by combustion was collected in an adsorbent (internal standard material PO ₄ ⁻ ).

Measuring device: IC-2001 manufactured by Tosoh Corporation
Separation column: TSKgel Super IC-AP (4.6 mmΦ × 150 mm)
Detector: Electrical conductivity detector Eluent: 2.7 mmol / L NaHCO ₃ + 1.8 mmol / L Na ₂ CO ₃
Commercially available DL-methionine (manufactured by Kishida Chemical Co., Ltd.) was used as it was as the sulfur-containing amino acid derivative represented by the general formula (1).

  Synthesis Example 1 Synthesis of Compound (7)

(In the formulas (3a), (5a), and (7), R is a beef tallow-derived long-chain alkyl group (for example, cetyl group, stearyl group, oleyl group, etc.).)
Synthesis of Diacylated Compound (5a) 9.51 g (30 mmol) of beef tallow propylenediamine (3a) (trade name: Diamine RRT, manufactured by Kao Corporation) in a 200 mL (liter) eggplant-shaped flask 00 g (75 mmol) and 40 g of diethyl ether were added. To this mixture, 8.47 g (75 mmol) of chloroacetyl chloride (4) was added dropwise at room temperature over 2 hours, and the mixture was further stirred at room temperature for 30 minutes. The reaction solution was transferred to a separatory funnel and extracted with ethyl acetate (15 mL × 2). The organic layers were combined and washed sequentially with saturated aqueous sodium bicarbonate (15 mL) and saturated brine (15 mL). After dehydration with sodium sulfate, the solvent was distilled off under reduced pressure, and the diacylated product represented by the above formula (5a) [hereinafter referred to as diacylated product (5a)]. The yield was 12.59 g and the yield was 89.3%.

¹ H-NMR (CDCl ₃ ) δ (ppm): 0.85-0.91 (m, beef tallow alkyl group-derived peak), 1.25-1.31 (m, tallow alkyl group-derived peak), 1.52 -1.80 (m, peak from beef tallow alkyl group), 1.96-2.05 (m, peak from beef tallow alkyl group), 3.22-3.48 (m, 6H), 4.04 (s, 2H), 4.08 (s, 2H), 5.32-5.38 (m, peak from beef tallow alkyl group), 7.59 (1H, brs), 2H not detected (overlap from tallow alkyl group-derived peak) Estimated)
Synthesis of Diacylated Compound (5b) In a 200 mL eggplant-shaped flask, 3.71 g (50 mmol) of 1,3-propanediamine (3a), 50 g of water, and 20 g of diethyl ether were weighed, and 20 wt% sodium hydroxide was added thereto. Aqueous solution 24.00 g (120 mmol) was added. To this mixture, 13.55 g (120 mmol) of chloroacetyl chloride (4) was added dropwise at 0 ° C. over 1 hour, and the mixture was further stirred at 0 ° C. for 1 hour. The resulting white solid was collected by filtration and washed successively with water and diethyl ether, and the diacylated product represented by the above formula (5b) [hereinafter referred to as diacylated product (5a)]. The yield was 10.41 g and the yield was 91.7%.

¹ H-NMR (DMSO-d ₆ ) δ (ppm): 1.55 (2H, quintet, J = 7.0 Hz), 3.03-3.10 (4H, m), 4.03 (4H, s ), 8.22 (2H, brs)
Synthesis of Dithioester Compound (6) 2.65 g (19.2 mmol) of potassium carbonate and 40 g of water were weighed into a 100 mL eggplant-shaped flask, and 2.65 g (19.2 mmol) of thiobenzoic acid was added thereto at 40 ° C. Stir for 30 minutes. To this, 1.82 g (8 mmol) of the diacylated product (5b) and 10 g of tetrahydrofuran were added, and the mixture was stirred at 40 ° C. for 3 hours. Thereafter, the mixture is further stirred at 0 ° C. for 1 hour, and the resulting white solid is collected by filtration and washed with water to give a dithioesterified product represented by the above formula (6) [hereinafter referred to as dithioesterified product (6)]. . The yield was 3.51 g, and the yield was 95.6%.

¹ H-NMR (CDCl ₃ ) δ (ppm): 1.65 (2H, quintet, J = 6.2 Hz), 3.23-3.32 (4H, m), 3.74 (4H, s), 6.88 (2H, brs), 7.43-7.52 (4H, m), 7.57-7.66 (2H, m), 7.95-8.00 (4H, m)
Synthesis of Compound (7) 11.53 g (26.8 mmol) of the above-mentioned dithioester compound (6) and 100 g of methanol were weighed into a 300 mL eggplant-shaped flask, and 10.71 g of 20 wt% aqueous sodium hydroxide solution was added thereto. (53.5 mmol) was added, and the mixture was stirred at room temperature for 2 hours under a nitrogen stream. To this was added 1.14 g (5 mmol) of the diacylated product (5a), and the mixture was stirred at room temperature for 20 hours. After the solvent was distilled off under reduced pressure, 30 g of tetrahydrofuran, 30 g of water, and 10.71 g (53.5 mmol) of a 20 wt% aqueous sodium hydroxide solution were added, and the mixture was stirred at 40 ° C. for 1 hour. The reaction solution was transferred to a separatory funnel and extracted with ethyl acetate (20 mL × 3). The organic layers were combined and washed sequentially with 20 mL of saturated aqueous sodium bicarbonate and 20 mL of saturated brine. After dehydration with sodium sulfate, the solvent was distilled off under reduced pressure to obtain Compound (7) in a yield of 15.40 g and a yield of 92.9%.

¹ H-NMR (CDCl ₃ ) δ (ppm): 0.85-0.91 (m, beef tallow alkyl group-derived peak), 1.25-1.31 (m, tallow alkyl group-derived peak), 1.50 -2.03 (m, tallow alkyl group-derived peak), 3.26-3.52 (m, 18H), 5.32-5.38 (m, tallow alkyl group-derived peak), 7.36 (1H, brs), 7.58 (1H, brs), 7.70 (1H, brs), 4H not detected (estimated to overlap with tallow alkyl group-derived peak)
Synthesis Example 2 Synthesis of Compound (9)

  2.15 (5 mmol) of the above-mentioned dithioester compound (6) and 20 g of methanol are weighed into a 50 mL eggplant-shaped flask, and 2.00 g (10 mmol) of a 20 wt% aqueous sodium hydroxide solution is added thereto, and a nitrogen stream is added. The mixture was stirred at room temperature for 2 hours. To this, 1.22 g (5 mmol) of 1,6-dibromohexane (8) was added and stirred at room temperature for 20 hours. The resulting white solid was collected by filtration and washed successively with water and methanol to obtain Compound (9) in a yield of 1.16 g and a yield of 76.3%.

¹ H-NMR (DMSO-d ₆ ) δ (ppm): 1.34 to 1.39 (8H, m), 1.50 to 1.63 (12H, m), 2.55 to 2.61 (8H) , M), 3.05-3.17 (16H, m), 8.02 (4H, brs)
Synthesis Example 3 Synthesis of Compound (10)

  2.15 g (5 mmol) of the above dithioesterified product (6) and 20 g of methanol are weighed into a 100 mL eggplant-shaped flask, and 2.00 g of a 20 wt% aqueous sodium hydroxide solution (10 mmol as sodium hydroxide) is added thereto. In addition, the mixture was stirred at room temperature for 2 hours under a nitrogen stream. To this was added 1.93 g (10 mmol) of 1-bromooctane, and the mixture was stirred at room temperature for 20 hours. After the solvent was distilled off under reduced pressure, 10 g of tetrahydrofuran, 10 g of water, and 2.00 g (10 mmol) of 20% aqueous sodium hydroxide solution were added, and the mixture was stirred at 40 ° C. for 1 hour. The reaction solution was transferred to a separatory funnel and extracted with ethyl acetate (2 × 10 mL). The organic layers were combined, and washed sequentially with 10 mL of saturated aqueous sodium bicarbonate solution, 10 mL of water, and 10 mL of saturated brine solution. The organic phase was separated and dehydrated with sodium sulfate, and then the solvent was distilled off under reduced pressure to obtain Compound (10) in a yield of 2.12 g and a yield of 95.1%.

¹ H-NMR (CDCl ₃ ) δ (ppm): 0.88 (6H, t, J = 7.0 Hz), 1.27-1.38 (20H, m), 1.52-1.79 (6H) M), 2.54 (4H, t, J = 7.0 Hz), 3.23 (4H, s), 3.29-3.83 (4H, m), 7.32 (2H, brs)
Preparation Example 1 Immobilization of Compound (7) on Alumina Carrier 0.1 g of Compound (7) synthesized in Synthesis Example 1 and 0.9 g of tetrahydrofuran were weighed into a 50 mL eggplant type flask and stirred at 40 ° C. for 30 minutes. . Thereafter, 0.9 g of alumina (trade name: activated alumina, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred at 40 ° C. for 30 minutes. After distilling off the solvent under reduced pressure, the obtained white powder was dried under reduced pressure at room temperature to prepare alumina impregnating and supporting Compound (7) at a ratio of 10% by weight. This is called adsorbent A.

Preparation Example 2 Immobilization of Compound (9) on Alumina Support 0.1 g of Compound (9) synthesized in Synthesis Example 2, 9 mL of chloroform, and 1 mL of methanol were weighed into a 50 mL eggplant type flask and stirred at 40 ° C. for 30 minutes. did. Thereafter, 0.9 g of alumina (trade name: activated alumina, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred at 40 ° C. for 30 minutes. After distilling off the solvent under reduced pressure, the obtained white powder was dried under reduced pressure at room temperature to prepare alumina impregnating and supporting 10% by weight of compound (9). This is called adsorbent B.

Example 1
The adsorbent A 300 mg (dry weight) prepared in Preparation Example 1 was added to 10 mL of a 1 mol / L hydrochloric acid solution containing 500 mg / L of palladium ions, and stirred at room temperature for 2 hours. Then, it filtered using the membrane filter with the hole diameter of 0.45 micrometer, and the adsorption amount of palladium ion was computed with 16.6 mg per 1 g of adsorption agent from the residual palladium ion density | concentration and initial concentration of a filtrate.

  Next, the adsorbent collected by filtration was washed with water and dried. 30 mg of the dried adsorbent was added to 10 mL of a desorbent prepared as a 1 mol / L hydrochloric acid aqueous solution having a DL-methionine concentration of 10% by weight and stirred at room temperature for 1 hour. Then, it filtered using the membrane filter with the hole diameter of 0.45 micrometer, As a result of calculating | requiring the desorption amount of palladium ion from the palladium ion density | concentration of a filtrate, the desorption rate of palladium ion was 100%.

Example 2
In Example 1, except that the DL-methionine concentration was changed to 2% by weight, the same procedure as in Example 1 was performed. As a result, the desorption rate of palladium ions was 98%.

Example 3
In Example 1, except that the DL-methionine concentration was 1% by weight, the same procedure as in Example 1 was performed. As a result, the desorption rate of palladium ions was 84%.

Example 4
The adsorbent B 400 mg (dry weight) prepared in Preparation Example 2 was added to 10 mL of a 1 mol / L hydrochloric acid solution containing 500 mg / L of palladium ions, and stirred at room temperature for 2 hours. Then, it filtered using the membrane filter with a hole diameter of 0.45 micrometer, and the adsorption amount of palladium ion was computed with 12.5 mg per 1 g of adsorption agent from the residual palladium ion density | concentration and initial concentration of a filtrate.

  Next, the adsorbent collected by filtration was washed with water and dried. 40 mg of the dried adsorbent was added to 10 mL of a desorbent prepared as a 1 mol / L hydrochloric acid aqueous solution having a DL-methionine concentration of 10% by weight and stirred at room temperature for 1 hour. Then, it filtered using the membrane filter with the hole diameter of 0.45 micrometer, As a result of calculating | requiring the desorption amount of palladium ion from the density | concentration of the palladium ion of a filtrate, the desorption rate of palladium ion was 100%.

Example 5
Silica Bond TAAcOH (adsorbent) 200 mg (dry weight) manufactured by SILICYCLE was added to 10 mL of 1 mol / L hydrochloric acid solution containing 500 mg / L of palladium ions, and stirred at room temperature for 2 hours. Then, it filtered using the membrane filter with the hole diameter of 0.45 micrometer, and the adsorption amount of palladium ion was computed with 19.5 mg per 1 g of adsorption agent from the residual palladium ion density | concentration and initial concentration of a filtrate.

  Next, after the adsorbent collected by filtration was washed with water and dried, 20 mg of the adsorbent was added to 10 mL of a desorbent prepared as a 1 mol / L hydrochloric acid aqueous solution having a DL-methionine concentration of 10% by weight and stirred at room temperature for 1 hour. Then, it filtered using the membrane filter with the hole diameter of 0.45 micrometer, As a result of calculating | requiring the desorption amount of palladium ion from the palladium ion density | concentration of a filtrate, the desorption rate of palladium ion was 100%.

Example 6
30 mg of compound (10) was dissolved in 2 mL of dichloromethane to obtain Extractant A. Extractant A and 10 mL of a 1 mol / L hydrochloric acid solution containing 500 mg / L of palladium ions were mixed and stirred at room temperature for 1 hour. The aqueous phase and the organic phase were separated using a separatory funnel. From the residual palladium ion concentration and the initial concentration in the aqueous phase, the amount of palladium ion extracted was calculated to be 166 mg per 1 g of Extractant A.

  Next, 10 mL of a 1 mol / L aqueous hydrochloric acid solution (back extractant) in which 1 g of DL-methionine is dissolved is added to the separated organic phase containing the extractant A, and the mixture is stirred for 1 hour at room temperature. The phase and the organic phase were separated. The back extraction rate of palladium ions determined from the palladium ion concentration of the obtained aqueous phase was 88%.

Example 7
Carbon anode (electrode area: 20 cm ² ) in 100 mL of 1.5 wt% DL-methionine aqueous solution containing 100 mg / L of palladium ions (pH 7, adjusted by diluting commercially available palladium standard solution (1000 ppm) with water) And when a cathode (electrode area: 20 cm ² ) was inserted and a constant current (current density 10 A / cm ² ) of 1 A (ampere) was passed at room temperature for 1 hour to reduce by electrolysis, a black precipitate was obtained. It was. A black precipitate was isolated by filtration using filter paper. As a result of ICP emission spectroscopic analysis measurement and ion chromatography measurement, the black precipitate was metallic palladium having a purity of 99% by weight or more.

Example 8
To 100 mL of a 1 mol / L hydrochloric acid solution containing 100 mg / L palladium ion and 1.5 wt% DL-methionine (adjusted using commercially available palladium chloride), sodium hydroxide was added until the solution became neutral. added. A carbon anode (electrode area: 20 cm ² ) and cathode (electrode area: 20 cm ² ) were inserted into the obtained liquid, and a constant current (current density 10 A / cm ² ) of 1 A (ampere) was applied for 1 hour at room temperature. As a result of reduction by electrolysis, a black precipitate was obtained. A black precipitate was isolated by filtration using filter paper. As a result of ICP emission spectroscopic analysis, the black precipitate was metallic palladium having a purity of 99% by weight or more.

Comparative Example 1
In Example 4, the same procedure as in Example 4 was carried out except that 10 mL of 28 wt% aqueous ammonia solution was used instead of the 1 mol / L hydrochloric acid aqueous solution having a DL-methionine concentration of 10 wt%. As a result, desorption of palladium ions was performed. The rate was 17%.

Comparative Example 2
As a result of performing in the same manner as in Example 4 except that 10 mL of 36 wt% hydrochloric acid was used instead of the desorbent of 1 mol / L hydrochloric acid aqueous solution having a DL-methionine concentration of 10 wt% in Example 4, the desorption rate of palladium ions Was 14%.

Comparative Example 3
In Example 7, instead of a 1.5 wt% DL-methionine aqueous solution containing 100 mg / L of palladium ions, 100 mL of a 3 wt% thiourea aqueous solution containing 100 mg / L of palladium (pH 7, commercially available palladium standard solution (1000 ppm)) was used. As a result of carrying out in the same manner as in Example 7 except that the sample was diluted with water and adjusted), a large amount of brown precipitate was formed. A brown precipitate was isolated by filtration using filter paper. As a result of ICP emission spectroscopic analysis, the palladium content of the brown precipitate was 2.9% by weight. As a result of ion chromatography measurement, it was found that the brown precipitate contained 91.9% by weight of sulfur.

Comparative Example 4
In Example 8, instead of the 1 mol / L hydrochloric acid solution containing 100 mg / L palladium ion and 1.5 wt% DL-methionine, 1 mol / L containing 100 mg / L palladium ion and 3 wt% thiourea As a result of carrying out in the same manner as in Example 8 except that 100 mL of hydrochloric acid solution (adjusted using commercially available palladium chloride) was used as a test solution, a large amount of brown precipitate was produced. A brown precipitate was isolated by filtration using filter paper. As a result of ICP emission spectroscopic analysis, the palladium content of the brown precipitate was 2.9% by weight. As a result of ion chromatography measurement, it was found that the brown precipitate contained 93.0% by weight of sulfur.

  By using the back extractant or desorbing agent and the noble metal recovery method of the present invention, it is possible to produce and collect precipitates of a highly pure noble metal very easily as compared with conventionally known techniques. For this reason, utilization in the resource recycling field | area which collect | recovers and reuses the expensive noble metal currently used for the discarded industrial or motor vehicle exhaust gas purification catalyst or an electrical appliance etc. is anticipated.

Claims (6)

A palladium ion back extractant or desorbent comprising an aqueous methionine solution . A palladium ion stripping agent or desorbing agent according to claim 1, that the water solution containing palladium ions obtained by contacting the extractant or adsorbents containing palladium ions reduction process to obtain a palladium A method for recovering palladium . Back extraction of billing and palladium ion stripping agent or desorbing agent according to claim 1, palladium ion, characterized in that contacting the extractant or adsorbents containing palladium ions obtain an aqueous solution containing palladium ions Method or desorption method. Palladium ion stripping agent or desorbing agent according to claim 1, and method for producing a palladium, wherein the reduction treatment the water solution containing the extractant or adsorbents containing palladium ions. The palladium ion desorption agent according to claim 1, the palladium ion is contacted with an adsorbent which has adsorbed, desorb method of palladium ions, characterized in that to desorb the palladium ions. A method for recovering palladium , comprising reducing the aqueous solution containing palladium ions obtained by the method for desorbing palladium ions according to claim 5 to precipitate and recover palladium .