JP6556685B2 - Platinum extractant, platinum extraction method, and platinum recovery method - Google Patents

Description

  The present invention relates to a platinum extractant, a platinum extraction method, and a platinum recovery method.

  Platinum is used in a wide range of fields such as electronic materials, magnetic recording materials, automobile exhaust gas purification catalysts, and fuel cell electrode catalysts, and is an extremely useful resource that is expected to further increase in future demand. On the other hand, platinum is a rare and expensive metal in terms of resources, and the main producing countries are biased to specific countries. Therefore, recycling by recovery and refining is essential in order to stably supply platinum. .

  Conventionally, various methods for recovering and purifying precious metals such as platinum have been known. Separation / recovery method of noble metal ions from aqueous solution includes adsorption method for solid-liquid contact using ion exchange resin or activated carbon, and solvent extraction method for liquid-liquid contact with organic solvent in which oil-soluble extractant is dissolved. There is.

  The former solid-liquid adsorption method is particularly suitable for the treatment of dilute solutions, but it takes a long time for the reaction and it is difficult to handle a large volume.

  On the other hand, the latter solvent-liquid contact method has the advantage that a relatively high concentration raw material liquid can be processed in large quantities, the operation is relatively easy, and continuous production is possible. Here, the solvent extraction method uses the difference in chemical affinity between two phases of oil water to distribute the target substance such as metal ions between the oil and water, and extracts the target substance by superimposing such distribution process. It is a method of separation. First, metal ions are moved from a solution containing metal ions to an organic solvent (extraction step). Next, metal ions are recovered from the organic solvent using a back extractant (release agent) such as a water-soluble complexing agent or a strong acid solution (back extraction step). A large amount of chemical reagent such as “extractant” is used in the extraction process, and “back extractant (release agent)” is used in the back extraction process.

  Since the extraction agent has a great influence on the separation performance of the target substance by this method, research on the development of the extraction agent has been extensively conducted so far. For example, Non-Patent Document 1 discloses a solvent extraction method of platinum using an extractant of N, N ′, dimethyl-N, N′-dibutylmalonamide having different alkyl side chains.

Ana Paula Paiva, Goncalo Ivo Carvalho, Maria Clara Costa, Ana M. Rosa da Costa & Carlos Nogueir, "The Solvent Extraction 97, Nand-Dimethylyl-Nand, N'-Dimethylinamide Worlds

However, although the extractant described in Non-Patent Document 1 is excellent in selectivity to platinum with respect to palladium, 1 M (M = mol dm ⁻³ ) sodium thiosulfate aqueous solution is required for stripping, and the stripping rate is also extracted. There is a problem that it is considerably lowered at the stage of repeated peeling. In addition, the extractant has low solubility in organic solvents, and halogen-containing and aromatic organic solvents such as 1,2-dichloroethane, toluene, and p-xylene are required. Further, as a result of further experiments by the present inventors, the extraction agent was dissolved in a mixed solvent of Varsol 80 and toluene having a low polarity and platinum was extracted, and as a result, the extraction rate of platinum was significantly reduced. Was found to occur.
Moreover, when amines, such as a trioctylamine, are used as an extracting agent, since precipitation generate | occur | produces at the time of peeling, it is known by experiment of the present inventors that it cannot use industrially.

  Accordingly, an object of the present invention is to provide a platinum extractant having high selectivity, extraction rate, and exfoliation rate with respect to platinum, a platinum extraction method using the same, and a platinum recovery method.

  As a result of diligent research to solve the above problems, the present inventors have found that a platinum extractant comprising an amide compound or a urea derivative having a specific structure has high selectivity, extraction rate, and exfoliation rate with respect to platinum. The present invention has been completed.

That is, the present invention is as follows.
1. A platinum extractant comprising an amide compound represented by the following general formula (I) or a urea derivative represented by the following general formula (II).

(In the formula, R ¹ and R ² each independently represents a substituted or unsubstituted linear or branched C _1-18 alkyl, C _2-18 alkenyl, or C _2-18 alkynyl.)

(In the formula, R ³ and R ⁴ each independently represent a substituted or unsubstituted linear or branched C _1-18 alkyl, C _2-18 alkenyl, or C _2-18 alkynyl.)
2. R ^{1 in the} formula (I) is a substituted or unsubstituted branched C _6-10 alkyl, and R ² is a substituted or unsubstituted linear C _1-9 alkyl, and the R in the formula (II) ^2. The platinum extractant as described in 1 above, wherein ³ is a substituted or unsubstituted branched C _6-10 alkyl, and R ⁴ is a substituted or unsubstituted linear C _2-6 alkyl.
3. The amide compound represented by the formula (I) is N- (2-ethylhexyl) -acetamide or N- (2-ethylhexyl) -octaneamide, and the urea derivative represented by the formula (II) is 1 3. The platinum extractant as described in 1 or 2 above, which is butyl-3- (2-ethylhexyl) urea.
4). A platinum extraction, wherein an acidic solution containing a noble metal containing platinum is subjected to solvent extraction with the platinum extractant according to any one of 1 to 3 dissolved in an organic solvent, and the platinum is extracted from the acidic solution. Method.
5). 5. The platinum extraction method according to 4, wherein the acidic solution contains platinum and at least one noble metal selected from the group consisting of rhodium, iridium, and copper, and platinum is extracted from the noble metal.
6). 6. The platinum extraction method according to 4 or 5 above, wherein the organic solvent is at least one organic solvent selected from a chlorinated solvent, an aromatic hydrocarbon, an aliphatic hydrocarbon, an ether, a ketone, and an ester. .
7). 7. The method for extracting platinum according to 6 above, wherein the organic solvent is a mixed solvent containing dodecane and 2-ethylhexanol in a volume ratio of 10: 0 to 4: 6.
8). After extracting platinum by the platinum extraction method according to any one of 4 to 7, the extraction agent from which the platinum has been extracted from the acidic solution is subjected to back extraction by mixing a back extraction reagent, A platinum recovery method for recovering platinum.
9. 9. The platinum recovery method according to 8 above, wherein the back extraction reagent is water.
10. 10. The method for recovering platinum according to 8 or 9, wherein the acidic solution contains platinum and at least one noble metal selected from the group consisting of rhodium, iridium, and copper, and recovers platinum from the acidic solution.

  Since the platinum extractant of the present invention is composed of an amide compound having a specific structure or a urea derivative, it can provide a platinum extractant having excellent selectivity, extraction rate, and exfoliation rate with respect to platinum. By using the platinum extractant dissolved in an organic solvent, platinum can be selectively and efficiently extracted into an organic solvent from an acidic solution containing a noble metal containing platinum. Furthermore, since the platinum extracted in the organic solvent can be peeled (back extraction) by using the back extraction reagent, platinum can be recovered from the acidic solution with high efficiency.

FIG. 1 is a diagram showing the results of measuring the concentration of each metal extracted in the aqueous phase in Example 12.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. Can do.

<Platinum extractant>
The platinum extractant of the present invention is a platinum extractant comprising an amide compound represented by the following general formula (I) or a urea derivative represented by the following general formula (II).

In the formula, R ¹ and R ² each independently represent a substituted or unsubstituted linear or branched C _1-18 alkyl, C _2-18 alkenyl, or C _2-18 alkynyl.

In the formula, R ³ and R ⁴ each independently represent a substituted or unsubstituted linear or branched C _1-18 alkyl, C _2-18 alkenyl, or C _2-18 alkynyl.

[Amide compound]
In the amide compound, R ^{1 in the} above formula (I) is preferably a substituted or unsubstituted branched C _1-18 alkyl or C _2-18 alkenyl, and R ² is a substituted or unsubstituted straight chain. It is a chain C _1-18 alkyl or C _2-18 alkenyl.

More preferably, in the amide compound, R ¹ is C _6-10 alkyl and R ² is C _1-9 alkyl. More preferably, R ¹ is C ₈ alkyl, R ² is C ₁ or C ₇ alkyl, specifically, for example, N- (2-ethylhexyl) -acetamide represented by the following formula (III), And N- (2-ethylhexyl) -octaneamide represented by the following formula (IV) is applicable.

  The various amide compounds can be appropriately produced by a conventionally known method, and the production method is not particularly limited. Below, the production method of N- (2-ethylhexyl) -acetamide represented by the above formula (III) and N- (2-ethylhexyl) -octaneamide represented by the above formula (IV) will be exemplified. However, regarding other amide compounds, those skilled in the art can produce the desired amide compounds by appropriately changing the conditions of the raw materials and the like as necessary.

First, 2-ethylhexylamine and triethylamine are added in an ice bath and dissolved in an organic solvent such as chloroform. Other organic solvents that can be used include dichloromethane, dichloroethane, toluene, diethyl ether, and the like.
Next, under cooling, acetyl chloride or octanoyl chloride is slowly added, heated and stirred overnight.
Furthermore, the obtained amide compound is produced by washing the resulting solution with a weakly basic aqueous solution such as a saturated sodium bicarbonate solution and distilled water, dehydrating and drying, and then removing the organic solvent.

[Urea derivatives]
In the above various urea derivatives, preferably, R ^{3 in the} above formula (II) is a substituted or unsubstituted branched C _1-18 alkyl or C _2-18 alkenyl, and R ⁴ is substituted or unsubstituted. It is a linear C _1-18 alkyl or C _2-18 alkenyl.
More preferably, in the amide compound, R ¹ is C _6-10 alkyl and R ² is C _2-6 alkyl. More preferably, in the urea derivative, R ³ is C ₈ alkyl and R ⁴ is C ₄ alkyl. Specifically, for example, 1-butyl-3- (2 represented by the following formula (V): -Ethylhexyl) urea.

  The urea derivative can be appropriately produced by a conventionally known method, and the production method is not particularly limited. Hereinafter, the production method of 1-butyl-3- (2-ethylhexyl) urea represented by the above formula (V) will be described as an example. By appropriately changing as necessary, a desired urea derivative can be produced.

First, 2-ethylhexylamine is added to butyl isocyanate at room temperature, dissolved in an organic solvent such as THF (tetrahydrofuran), and stirred.
Next, the urea derivative is produced by removing the organic solvent after 3 hours.

By using an extractant composed of the above specific amide compound or urea derivative, it is presumed that the selectivity to platinum, the extraction rate, and the peeling rate are increased due to the following mechanism.
That is, the selectivity of platinum is high because extraction occurs based on the weak interaction between the platinum anion and the secondary amide hydrogen in the amide compound or the urea hydrogen in the urea derivative, and the interaction with other metal cations. This is thought to be due to weak action.
Moreover, it is thought that the high extraction rate of platinum is because the weak interaction with platinum can be sufficiently compensated by adjusting the concentration of the extraction reagent as appropriate.
In addition, the high peeling rate of platinum is because the extraction is based on the weak interaction between the platinum anion and the secondary amide hydrogen in the amide compound or the urea hydrogen in the urea derivative. It is thought that it is to become.
In addition, the extraction reagent of the extractant and the effect of selectivity largely depend on the functional group. For example, it is considered that the fat solubility of the functional group is also involved. When the alkyl chain of the functional group becomes long (the number of C increases), the solubility in an organic solvent increases. Furthermore, when the functional group contains an unsaturated bond, the lipid solubility is improved, and thus the extraction ability is considered to be increased.

<Platinum extraction and recovery methods>
In order to extract platinum using the above extractant, an acidic solution (aqueous phase) containing a noble metal containing platinum is added to an organic solution (organic phase) in which the extractant is dissolved, followed by solvent extraction. (Positive extraction process). Thereby, platinum can be selectively extracted into the organic phase. In some cases, platinum is extracted in the third phase described later.

  In addition, the organic solvent and / or the third phase after extraction of platinum is separated, and a separation solution containing a back-extraction reagent is added to this and stirred, so that platinum is back-extracted into an aqueous solution and separated. (Back extraction process).

  The organic solvent is not particularly limited as long as it is a solvent in which the extractant and the metal extraction species are dissolved. For example, chlorinated solvents such as chloroform, dichloromethane, dichloroethane, and chlorobenzene, aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as hexane, dodecane, kerosene, and cycloalkanes, ethers, and ketones And esters. These organic solvents may be used alone or in combination, and alcohols such as 2-ethylhexanol and 1-octanol may be mixed.

  Among them, from the viewpoint of reducing environmental burden and solubility, the organic solvent is preferably a mixed solvent of an aliphatic hydrocarbon and an alcohol that is difficult to partition into water, an aliphatic hydrocarbon, an aromatic hydrocarbon, or a mixture thereof. Is preferred. In particular, it is preferable to use a mixed solvent of dodecane and 2-ethylhexanol from the viewpoints of reduction of environmental load, regulation of hazardous materials, solubility, and high extraction rate.

  Furthermore, in the case of a mixed solvent of aliphatic hydrocarbon and alcohol, when the extractant and the acidic solution to be treated are mixed, a third phase other than the aqueous phase and the organic phase (platinum that is not concentrated and distributed to the organic phase). From the viewpoint that formation of a complex solid or emulsion) can be suppressed, the mixing ratio (volume ratio) is preferably 10: 0 to 4: 6, and 8: 2 to 4: 6. More preferably. In particular, when the extractant is the urea derivative, the mixing ratio (volume ratio) is preferably 5: 5 to 4: 6. When the third phase is formed, platinum is extracted not only in the organic solvent but also in the third phase, so that the extraction rate of platinum into the organic solvent becomes relatively small. When the third phase is formed, platinum is also contained in the third phase. Therefore, it is preferable to perform back extraction of platinum from the third phase.

  Further, in the case of a mixed solvent of aliphatic hydrocarbon and alcohol, from the viewpoint that the extraction rate of platinum can be increased, the mixing ratio (volume ratio) may be set to 10: 0 to 4: 6. preferable. In particular, when the extractant is the amide compound, the mixing ratio (volume ratio) is preferably 9.5: 0.5 to 9: 1. Moreover, when making an extractant into the said urea derivative, it is preferable that each mixing ratio (volume ratio) shall be 8: 2-4: 6, and it is more preferable to set it as 6: 4-5: 5.

  Also when using the said urea derivative as an extractant, from a viewpoint of a high extraction rate, it is preferable to use the mixed solvent of an aliphatic hydrocarbon and alcohol preferably from an organic solvent.

  When the extractant is the amide compound, the concentration of the extractant in the organic solution (organic phase) is preferably 0.15M to 1.2M, and preferably 0.4M to 1.2M. It is more preferable to set it to 0.6M to 1.0M.

  When the extractant is the urea derivative, the concentration of the extractant in the organic solution (organic phase) is preferably 0.1M to 1.2M, and is preferably 0.2M to 1.2M. More preferably, it is more preferably 0.4M to 1.0M.

  By setting the concentration of the extractant within the above range, high selectivity to platinum and high extraction rate of platinum can be obtained.

The acidic solution to be treated is an acidic solution containing a noble metal including platinum. Examples of the acidic solution include hydrochloric acid, nitric acid, and aqua regia. The noble metal other than platinum contained in the acidic solution is not particularly limited. For example, rhodium, iridium, ruthenium, copper, iron, nickel, cobalt, lead, zinc and tin.
For example, when the acidic solution contains platinum and at least one noble metal selected from the group consisting of rhodium, iridium, and copper, the platinum extractant of the present invention extracts platinum from the noble metal excluding platinum. It becomes possible to do.

  The concentration of platinum contained in the acidic solution is preferably 0.01 g / L to 100 g / L, more preferably 20 g / L to 80 g / L, and still more preferably 40 g / L to 60 g / L. By setting it as the said range, the volume of a liquid can be reduced and a processing facility can be reduced in size. If the concentration is higher than the above range, it is necessary to concentrate, resulting in poor economic efficiency. In order to set the concentration of platinum contained in the acidic solution within the above range, for example, the acidic solution may be diluted with pure water or the like.

  The mixing ratio between the extractant and the acidic solution to be treated is 5: 1 to 1: 5 (water phase: organic phase volume ratio) regardless of whether the extractant is the amide compound or the urea derivative. Preferably, it is preferably 3: 1 to 1: 3, and more preferably 1: 1. By setting the mixing ratio in the above range, high selectivity for platinum and high extraction rate of platinum can be obtained.

  As stirring conditions for the extractant and the acidic solution to be treated, the stirring time is usually 30 minutes to 300 minutes, preferably 60 minutes to 180 minutes. The stirring (extraction) temperature is usually from room temperature to 30 ° C. The stirring speed is usually 50 rpm to 1000 rpm, and preferably 100 rpm to 300 rpm.

  About the acid concentration in the case of platinum extraction, it can be made into the wide range ranging from the strongly acidic area | region of about 5M to the weakly acidic area | region of 0.01M or more. If impurities are contained in the acidic solution containing platinum, it is preferable to add an organic solution of the extractant while adjusting the acid concentration so that impurities are hardly extracted.

  In particular, the acid concentration is preferably 0.5M to 3.0M. This is because high selectivity to platinum can be achieved within the above range.

  As the back extraction reagent, for example, water, aqueous solutions of nitric acid, ammonia, and sodium hydroxide are used. In particular, in the present invention, from the viewpoint that platinum can be easily extracted using water by extracting platinum using an extractant composed of a compound having a specific structure, as a back extraction reagent, It is preferable to use water. If water can be used as a back-extraction reagent, there is no need to separately prepare another back-extraction reagent, and platinum can be easily back-extracted.

  The lower limit of pH is not particularly limited, but when high-concentration nitric acid is mixed, platinum back-extraction proceeds, and generally organic extractants are degraded by high-concentration acids and alkalis. In view of the fact that it is believed that the pH is promoted, the pH during extraction is preferably about 2 or more, more preferably 3 or more.

[Extraction rate]
By mixing an organic phase containing an extractant and an aqueous phase that is an acidic solution, platinum is extracted (positively extracted) into the organic phase. The extraction rate of the metal containing platinum is represented by the following formula.
Extraction rate (% E) = (Ci−Ce) / Ci × 100
Ci: initial metal ion concentration (in aqueous phase) Ce: post-equilibrium metal ion concentration (in aqueous phase)

  Although the measuring method in particular of metal ion concentration is not restrict | limited, For example, it can measure using ICP-AES (made by SHIMADZU, ICPS-8100) etc.

  The extraction rate (% E) is preferably 20 to 100%, more preferably 50 to 100%, and still more preferably 90 to 100%.

[Back extraction rate]
By mixing the organic phase after the normal extraction and the back extraction reagent (aqueous phase), platinum is back extracted into the aqueous phase. The back extraction rate (peeling rate) of the metal containing platinum is expressed by the following formula.
Back extraction rate (% S) = Cs / (Ci−Ce) × 100
Cs: Metal ion concentration after back extraction (in water phase) Ci: Initial metal ion concentration (in water phase) Ce: Metal ion concentration after equilibrium (in water phase)

  The back extraction rate is preferably 70 to 100%, more preferably 80 to 100%, and further preferably 95 to 100%.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not restrict | limited to the following example.

[Extractant]
<Production Example 1>
Extractant A: N- (2-ethylhexyl) -acetamide In an ice bath, 2-ethylhexylamine and triethylamine were added and dissolved in chloroform. Next, under cooling, acetyl chloride was added slowly, heated and stirred overnight. Furthermore, the obtained solution was washed with a saturated sodium hydrogen carbonate solution and distilled water which are weakly basic aqueous solutions, dehydrated and dried, and then the organic solvent was removed to produce N- (2-ethylhexyl) -acetamide.

<Production Example 2>
Extractant B: N- (2-ethylhexyl) -octaneamide N- (2-ethylhexyl) -octaneamide was produced in the same manner as in Production Example 1 except that acetyl chloride was changed to octanoyl chloride. did.

<Production Example 3>
Extractant C: 1-butyl-3- (2-ethylhexyl) urea At room temperature, 2-ethylhexylamine was added to butyl isocyanate, dissolved in THF (tetrahydrofuran) as an organic solvent, and stirred. After 3 hours, C: 1-butyl-3- (2-ethylhexyl) urea was produced by removing the organic solvent.

<Production Example 4>
Extractant D: N, N′-dimethyl-N, N′-dibutylmalonamide In an ice bath, N-methylbutylamine and triethylamine were added and dissolved in chloroform. Next, under cooling, malonyl chloride was added slowly, heated and stirred overnight. Further, the obtained solution was washed with a saturated sodium bicarbonate solution and distilled water, which are weakly basic aqueous solutions, dehydrated and dried, and then the organic solvent was removed, whereby N, N ′ represented by the following formula (VI): -Dimethyl-N, N'-dibutylmalonamide was obtained.

<Production Example 5>
Extractant E: N-2-ethylhexylurea Aqueous urea solution, ethanol / water solution of 2-ethylhexylamine, and hydrochloric acid were mixed. The solvent of the reaction solution was distilled off, the residue was added to chloroform and washed with 1.0 M hydrochloric acid solution to remove unreacted urea and 2-ethylhexylamine. Water was removed with anhydrous sodium sulfate, and then chloroform was removed. By recrystallization using hexane, N-2-ethylhexyl urea represented by the following formula (VII) was obtained.

<Production Example 6>
Extractant F: N- (2-ethylhexyl) -3- (methylphenylamino) -propanamide 2-ethylhexylamine was added dropwise to a dry dichloromethane solution of acryloyl chloride at 0 ° C. and stirred. After stirring at room temperature for 30 minutes, the reaction was quenched with a saturated sodium hydrogen carbonate solution, the organic phase was washed with water, and then anhydrous sodium sulfate was added and dried. The organic phase was distilled off to obtain N- (2-ethylhexyl) -2-propanamide. Under a nitrogen stream, N- (2-ethylhexyl) -2-propanamide, N-methylaniline, and silicon tetrachloride were mixed at 70 ° C. and stirred for 16 hours. The mixture was dissolved in dichloromethane, washed with water, and then dehydrated and dried over anhydrous magnesium sulfate. The solvent was distilled off and the viscous liquid product was purified by silica gel column chromatography to obtain N- (2-ethylhexyl) -3- (methylphenylamino) -propanamide represented by the following formula (VIII). The eluent used was dichloromethane containing 10% methanol.

[Organic solvent]
Solvent A: Dodecane / 2-ethylhexanol (80 vol% / 20 vol%)
Solvent B: Dodecane Solvent C: Chloroform Solvent D: Shellsol TK (second petroleum, linear paraffin base, aromatic component included)
Solvent E: Shellzol D70 (third petroleum, linear paraffin only)
Solvent F: Toluene

[Acid solution]
Acidic solution A: Pt (IV) 0.300M (58.5 g / L), Rh (III) 0.100M (10.3 g / L), Ir (III) 0.010M (1.92 g / L), Hydrochloric acid solution containing Cu (II) 0.300M (19.1 g / L) and having a hydrochloric acid concentration of 2.0 M (used in Examples 1 to 11)
Acidic solution B: Pt (IV), Ir (III), Rh (III), Fe (III), Cu (II), Ni (II), Co (II), Zn (II), Pb (II) Hydrochloric acid solution having a hydrochloric acid concentration of 0.01 M to 10 M each containing 0.1 mM (used in Example 12)
Acidic solution C: A hydrochloric acid solution having a hydrochloric acid concentration of 7.0 M containing Pt (IV) (0.10 g / L) (used in Comparative Example 1)
Acidic solution D: a hydrochloric acid solution having a hydrochloric acid concentration of 1.0 M containing 1.0 mM each of Pt (IV), Cu (II), Ni (II), Zn (II), Co (II), and Fe (III) (Used in Comparative Example 2)
Acidic solution E: 6.0 M hydrochloric acid solution containing 0.01 M Pt (IV) (used in Comparative Example 3)

[Extraction rate]
The extraction rate of metal is represented by the following formula.
% E (extraction rate) = (Ci−Ce) / Ci × 100
Ci: Initial metal ion concentration (in aqueous phase) Ce: Post-equilibrium metal ion concentration (in aqueous phase) The metal ion concentration was measured using ICP-AES (manufactured by SHIMADZU, ICPS-8100).

[Back extraction rate]
The back extraction rate of metal is represented by the following formula.
% S (back extraction rate) = Cs / (Ci-Ce) × 100
Cs: Metal ion concentration after back extraction (in aqueous phase) Ci: Initial metal ion concentration (in aqueous phase) Ce: Metal ion concentration after equilibrium (in aqueous phase) The measuring method of metal ion concentration is ICP-AES (manufactured by SHIMADZU) , ICPS-8100) and the like.

<Test Example 1>
[Example 1]
Extractant A (N- (2-ethylhexyl) -acetamide) was diluted with solvent A (dodecane / 2-ethylhexanol (80 vol% / 20 vol%)). The extractant concentration was 1.0M. The acidic solution A as an extraction stock solution and mixed at a volume ratio of 1: 1 was shaken and stirred using a magnetic stirrer for 3 hours at a temperature of 30 degrees and a speed of 150 rpm. After stirring, when the concentration of each metal in the aqueous phase was measured, the Pt extraction rate into the organic phase was 33.0%, and the extraction rates of other elements were 0%. Further, after Pt extraction, the organic phase was mixed with the same volume of water as a back extraction reagent. As a result, equilibrium was reached at the time of stirring for 3 hours, and the Pt back-extraction rate was 95.5%. The results are shown in Table 1.

[Example 2]
Example 1 was repeated except that the acidic solution A used in Example 1 was diluted twice with pure water to make an extraction stock solution. As a result, the Pt extraction rate was 50.0%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 91.2%. The results are shown in Table 1.

[Example 3]
Example 1 was repeated except that the extractant was changed to extractant B (N- (2-ethylhexyl) -octanamide). As a result, the Pt extraction rate into the organic phase was 15.8%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 74.8%. The results are shown in Table 1.

[Example 4]
Example 3 was repeated except that solvent A was changed to solvent B (dodecane). As a result, the Pt extraction rate into the organic phase was 24.7%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 100.0%. The results are shown in Table 1.

[Example 5]
Example 3 was repeated except that solvent A was changed to solvent C (chloroform). As a result, the Pt extraction rate into the organic phase was 22.0%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 92.3%. The results are shown in Table 1.

[Example 6]
Example 3 was repeated except that solvent A was changed to solvent D (Shellsol TK). As a result, the Pt extraction rate into the organic phase was 19.1%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 96.2%. The results are shown in Table 1.

[Example 7]
Example 3 was repeated except that solvent A was changed to solvent E (Shellsol D70). As a result, the Pt extraction rate into the organic phase was 12.0%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 98.2%. The results are shown in Table 1.

[Example 8]
Example 1 was repeated except that the extractant was changed to extractant C (1-butyl-3- (2-ethylhexyl) urea). As a result, the Pt extraction rate into the organic phase was 53.0%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 70.3%. The results are shown in Table 1.

[Example 9]
Example 8 was repeated except that solvent A was changed to solvent C (chloroform). As a result, the Pt extraction rate into the organic phase was 57.0%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 51.2%. The results are shown in Table 1.

[Example 10]
Example 8 was repeated except that solvent A was changed to solvent D (Shellsol TK). As a result, the Pt extraction rate into the organic phase was 27.0%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 100.0%. The results are shown in Table 1.

[Example 11]
Example 8 was repeated except that solvent A was changed to solvent E (Shellsol D70). As a result, the Pt extraction rate into the organic phase was 25.0%, and the extraction rates of other elements were 0%. The Pt back extraction rate was 97.8%. The results are shown in Table 1.

[Example 12]
Extractant B (N- (2-ethylhexyl) -octanamide) was diluted with solvent A (dodecane / 2-ethylhexanol (80 vol% / 20 vol%)). The extractant concentration was 1.0M. An acidic solution B (hydrochloric acid concentration of 0.01 to 10 M) as an extraction stock solution and mixed at a volume ratio of 1: 1 was shaken and stirred for 3 hours at a temperature of 30 degrees and a speed of 150 rpm. After stirring, the concentration of each metal in the aqueous phase was measured. The results are shown in FIG. FIG. 1 shows that, for example, Pt is extracted with high selectivity at a hydrochloric acid concentration of 0.01M.

[Comparative Example 1]
Extractant D (N, N′-dimethyl-N, N′-dibutylmalonamide) was diluted with solvent F (toluene). The extractant concentration was 0.05M. The acidic solution C as an extraction stock solution and mixed at a volume ratio of 1: 1 was shaken and stirred for 30 minutes at a temperature of 30 degrees and a speed of 1000 rpm. After stirring, when the concentration of each metal in the aqueous phase was measured, the Pt extraction rate into the organic phase was 90.0%. Further, after extraction with Pt, the organic phase was mixed with a 1.0 M hydrochloric acid solution of 0.1 M potassium thiocyanate in the same volume as a back extraction reagent. As a result, equilibrium was reached at the time of stirring for 3 hours, and the Pt back extraction rate was 35.0%. The results are shown in Table 1.

[Comparative Example 2]
Extractant E (N-2-ethylhexyl urea) was diluted with solvent C (chloroform). The extractant concentration was 0.05M. The acidic solution D used as an extraction stock solution and mixed at a volume ratio of 1: 1 was shaken and stirred at a temperature of 30 degrees for 24 hours. After stirring, when the concentration of each metal in the aqueous phase was measured, the Pt extraction rate into the organic phase was 40.0%. On the other hand, the Cu extraction rate was 5%. The results are shown in Table 1.

[Comparative Example 3]
Extractant F (N- (2-ethylhexyl) -3- (methylphenylamino) -propanamide) was diluted with solvent F (toluene). The extractant concentration was 0.05M. An acidic solution E as an extraction stock solution and mixed at a volume ratio of 1: 1 was shaken and stirred at a temperature of 30 degrees for 24 hours. After stirring, when the concentration of each metal in the aqueous phase was measured, the Pt extraction rate into the organic phase was 90.0%. However, the extraction rate shown here is the extraction rate transported to the third phase. The results are shown in Table 1.

  From the above results, it was found that platinum can be selectively extracted and its extraction rate and back-extraction rate can be increased by using the extraction agent comprising the specific amide compound or urea derivative according to the present invention. . Moreover, the back extraction of Pt could be easily performed with water.

In Comparative Example 1, since N, N′-dimethyl-N, N′-dibutylmalonamide was used as the extractant, it was necessary to use potassium thiocyanate instead of water during back extraction.
In Comparative Example 2, N-2-ethylhexylurea is used as an extractant, and in this case, 5.0% of Cu (II) is extracted under the coexistence conditions of Pt (IV) and Cu (II), Pt selectivity was inferior.
In Comparative Example 3, N- (2-ethylhexyl) -3- (methylphenylamino) -propanamide is used as the extractant. In this case, the extraction rate of Pt (IV) is as high as 90%, but organic It was not the proportion of platinum extracted into the phase, but the concentration of platinum removed from the aqueous phase, ie, the formation of a third phase, and was not considered an extractant that could be used in an actual process.

<Test Example 2: Effect of organic diluent composition on extraction rate>
For the organic phase diluent having a diluent with the composition shown in Table 2 below, the content ratio (D: 2EH) of dodecane / 2-ethylhexanol in the diluent (solvent) was changed at the ratio shown in Table 2 below. The influence on the extraction rate of platinum was investigated. The experiment was conducted according to the following conditions. First, an organic phase in which an extractant was dissolved with an organic diluent (organic solvent) and an acidic solution were mixed in equal amounts, and then shaken to perform phase separation. ICP measurement was performed on the obtained aqueous phase, and the extraction rate (% E) of platinum was obtained. The results are shown in Table 2 below.

[Experimental conditions]
Extractant A Extractor A: 1.0 M N- (2-ethylhexyl) -acetamide Extractant B: 1.0 M N- (2-ethylhexyl) -octanamide Extractor C: 1.0 M 1 -Butyl-3- (2-ethylhexyl) urea-organic diluent (organic solvent): dodecane / 2-ethylhexanol-acidic solution: Pt (IV) = 295 mM (57.5 g / L), Ir (III) = 10 0.0 mM (1.92 g / L), Rh (III) = 115 mM (11.8 g / L), Cu (II) = 262 mM (16.6 g / L)
-Phase ratio: V _org. : V _aq. = 3 cm ³ : 3 cm ³
(V _org .: Volume of organic phase, V _aq. Volume of aqueous phase)
-Positive extraction time: 3.0 hours-Temperature: 30 ° C
-Shaking speed: 150 rpm
Measurement: ICP-AES (Shimadzu, ICPS-8100)
% E (extraction rate) = (Ci−Ce) / Ci × 100
Ci: initial metal ion concentration (in aqueous phase) Ce: post-equilibrium metal ion concentration (in aqueous phase)

  From the above results, in the case of the extractant A (N- (2-ethylhexyl) -acetamide), the extraction ratio of platinum is particularly improved by setting the mixing ratio of dodecane and 2-ethylhexanol to 10: 0 to 8: 2. It turned out to be high. Further, in the case of the extractant B (N- (2-ethylhexyl) -octaneamide), the extraction ratio of platinum is adjusted by setting the mixing ratio of dodecane and 2-ethylhexanol to 9.5: 0.5 to 9: 1. Was found to be particularly high. Further, in the case of the extractant C (1-butyl-3- (2-ethylhexyl) urea), the extraction ratio of platinum is particularly improved by setting the mixing ratio of dodecane and 2-ethylhexanol to 6: 4 to 5: 5. It turned out to be high.

Claims (10)

It consists urea derivative represented by the following Symbol formula (II), platinum extractant.
(In the formula, R ³ and R ⁴ each independently represent a substituted or unsubstituted linear or branched C _1-18 alkyl, C _2-18 alkenyl, or C _2-18 alkynyl.) ^{R 3} is a substituted or unsubstituted branched _{C 6-10} alkyl previous following formula (II), and ^{R 4} is a substituted or unsubstituted, straight _{C 2-6} alkyl, according to claim 1 Platinum extractant. Urea derivative represented by the front following formula (II) is 1-butyl-3- (2-ethylhexyl) urea, platinum extraction agent according to claim 1 or 2.   A platinum that is subjected to solvent extraction with the platinum extractant according to any one of claims 1 to 3 in which an acidic solution containing a noble metal including platinum is dissolved in an organic solvent, and extracts the platinum from the acidic solution. Extraction method.   The platinum extraction method according to claim 4, wherein the acidic solution contains platinum and at least one noble metal selected from the group consisting of rhodium, iridium, and copper, and platinum is extracted from the noble metal.   The platinum extraction according to claim 4 or 5, wherein the organic solvent is at least one organic solvent selected from a chlorinated solvent, an aromatic hydrocarbon, an aliphatic hydrocarbon, an ether, a ketone, and an ester. Method.   The method for extracting platinum according to claim 6, wherein the organic solvent is a mixed solvent containing dodecane and 2-ethylhexanol in a volume ratio of 10: 0 to 4: 6.   After extracting platinum by the platinum extraction method according to any one of claims 4 to 7, back extraction is performed by mixing a back extraction reagent with the extractant from which the platinum has been extracted from the acidic solution. A method for recovering platinum, which is performed to recover platinum.   The method for recovering platinum according to claim 8, wherein the back-extraction reagent is water.   The platinum recovery method according to claim 8 or 9, wherein the acidic solution contains platinum and at least one noble metal selected from the group consisting of rhodium, iridium, and copper, and recovers platinum from the acidic solution.