JP5881044B2 - Method for preparing solid extractant and method for extracting palladium - Google Patents

Description

The present invention relates to a method of extracting the adjustment direction Ho及 beauty palladium solid extractant, in particular adjustment direction suitable solid extractant is applied in the efficient extraction of palladium from the solution, such as high-level radioactive liquid waste Ho及 And a method for extracting palladium.

  The high-level radioactive liquid waste generated in the spent nuclear fuel reprocessing step or the like is finally treated as a glass solid.

  Such high-level radioactive liquid waste contains a large amount of platinum group elements (metals), including palladium (Pd), which is a useful metal, and these platinum group elements produce a glass solid from the liquid waste. Therefore, development of a technique for separating and recovering the platinum group element from the waste liquid has been desired because it accumulates and becomes a factor that hinders vitrification.

  As a technique that meets such a demand, for example, a polymer-type extractant comprising polydiphenylvinylphosphine oxide (PDPVPO) disclosed in Patent Document 1 and polydialkylvinylphosphine oxide (PDAVPO) disclosed in Patent Document 2 It is conceivable to separate and recover platinum group elements from high-level radioactive liquid waste.

JP 2007-91824 A JP 2010-179287 A

Sasaki, Sadaaki, Han Tung, “Applicability of polymer-type extractants for white metal elements” The Atomic Energy Society of Japan, Spring 2012 Proceedings, page 371 Sasaki, Sadaaki, Hanri Sung, “Separation and Recovery of White Metal Elements Using Polymer Bead-Type Extractant” The Atomic Energy Society of Japan, Autumn 2011 Proceedings, page 122 Sasaki, Sadaaki, Han Tung, “Separation and Recovery of White Metal Elements Using Polymer Type Extractant” The Atomic Energy Society of Japan, 2011 Spring Annual Meeting Proceedings, page 170

  However, although PDPVPO disclosed in Patent Document 1 and PDAVPO disclosed in Patent Document 2 are effective as an extractant, since they are powdery polymers and have a low specific gravity, a solution such as an aqueous solution is mixed. When contacting by means of, for example, it is necessary to use liquid-liquid extraction by dissolving in an organic solvent, there is a problem that the organic solvent must be separated and recovered after extraction.

The present invention has been made to solve the above-mentioned conventional problems. Since liquid-solid extraction without using an organic solvent can be performed, it is not necessary to separate and recover the organic solvent, and the extraction performance for palladium is also improved. and to provide an excellent method of extracting the adjustment direction Ho及 beauty palladium solid extractant.

In order to provide a technique capable of performing liquid-solid extraction without using an organic solvent and having excellent extraction performance for palladium , the present inventors have provided a polymer-type extractant and a polymer bead-type extractant in which the polymer-type extractant is beaded. And, a silica-supported polymer-type extractant in which a polymer-type extractant was supported on silica in an appropriate range was examined. As a result, it was found that polyphenyl vinyl sulfide (PPVS), which is a silica-supported polymer type extractant, can be liquid-solid extracted without using an organic solvent and has excellent extraction characteristics.

The present invention has been made on the basis of the above findings, and is a method for preparing a solid extractant used when extracting palladium from a solution, which comprises adding silica gel to a chloroform solution of polyphenylvinyl sulfide, and overnight at room temperature. After stirring, the solvent is removed under vacuum to obtain silica gel on which polyphenylvinyl sulfide is supported, thereby solving the above-mentioned problems.
Here, phenyl vinyl sulfide (monomer) produced by the substitution reaction of the following formula (1) and the elimination reaction of the following formula (2) is polymerized by the polymerization reaction of the following formula (3) to obtain the above poly Ru can generate phenyl vinyl sulfide.

The present invention also solves the above-mentioned problem by bringing a solution into contact with the solid extractant prepared by the above method and extracting palladium from the solution.

According to the present invention, the solid extractant, by the polyphenyl vinyl sulfide was prepared responsible lifting the silica, the solution is contacted by mixing or the like to the solid extractant, when separating and recovering palladium from the solution In addition to the liquid-solid extraction without using an organic solvent, an excellent extraction rate could be obtained.

Diagram showing effective loading range of polyphenyl vinyl sulfide (PPVS) on silica Diagram showing comparison of extraction rate of palladium by polymer bead type PTPRS and silica supported type PPVS

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

で表されるポリフェニルビニルスルフィドを、シリカに担持して調製される。 The solid extractant according to the present invention has a structural formula

It is prepared by supporting polyphenylvinyl sulfide represented by the following formula on silica.

This PPVS can produce phenyl vinyl sulfide (monomer) produced by the substitution reaction of the formula (1) and the elimination reaction of the formula (2) by the polymerization reaction of the formula (3), and then (4) As shown in the formula, the solid extractant can be produced by supporting silica gel (silica): SiO ₂ .

  The monomers synthesized by the formulas (1) and (2) were polymerized by the formula (3) to obtain PPVS having a mass average molecular weight (Mw) of 36,900 and a molecular weight distribution (Mw / Mn) of 1.66.

  The molecular weight was measured by gel permeation chromatography using Tosoh's product name “GMHHR-H * 2” as a column and N-methyl-2-pyrrolidone as a solvent and polystyrene as a standard.

  Next, a plurality of solid extractants in which the obtained PPVS was supported on silica at different ratios were prepared, and the extraction rate with respect to palladium was evaluated.

  As the loading method, slica gel 60 (silica gel, particle size 40-50 μm) manufactured by Kanto Chemical Co., Inc. was used as silica, and the silica gel was added to a PPVS chloroform solution according to the formula (4) and stirred overnight at room temperature. Thereafter, the solvent was removed under vacuum to obtain silica gel carrying PPVS.

For each of the 9.1% by mass and 16.7% by mass solid extractants having different PPVS loading ratios on silica, a sample solution in which 0.03 mmol of palladium nitrate was dissolved in 1 mol of nitric acid solution was used as the extractant amount. The mixture was mixed with 0.03 mmol PPVS under the same conditions, stirred for 12 hours at room temperature, separated, and the palladium concentration in the filtrate was measured by an IPC emission spectrophotometer (HORIBA ULTMA2) to obtain the extraction rate.

  The results are shown in Table 1 and the graph of FIG.

  This solid extractant is considered to capture and extract palladium by complex formation in which 2 atoms of sulfur coordinate to 1 atom of palladium.

As can be seen from FIG. 1, as the solid extractant with PPVS supported on silica (hereinafter also referred to as silica-supported extractant), a support ratio in the range of 0.1% by mass to 25 % by mass is effective.

For carrying ratio 9.1 mass% of the solid extractant, use the extract polishes of 0.03mmol to the sample solution of one mole of nitric acid containing palladium ions of the metal amount 0.005 mmol, 60-fold Table 2 shows the extraction rate obtained by extracting in the same manner as in Example 1 under the condition of excess amount of the extractant and comparing the obtained extraction rate with the result of the unsupported polymer type extractant.

  Table 2 also shows the results of the same extraction of PVS-Co-5MMA and PDPVPO polymers supported by silica and those not supported by the following structural formula.

From Table 2, the silica-supported polymer type extractant (PPVS, PVS-Co-5MMA) is
The extraction rate is equal to or higher than that of the unsupported polymer type extractant.

  Table 3 shows the results of evaluating the influence of the radiation (γ-ray) irradiation on the extraction rate for each of the silica-supported and non-supported PPVSs shown in Table 2. The irradiated dose is 1.0 MGy.

  From this table, it can be seen that any of the extractants shows a high extraction rate without any adverse effects due to γ-ray irradiation, and can be used even under severe conditions for treating high-level radioactive waste liquid.

  Table 3 also shows the results of polymer bead type PPPPS (Poly Tri Phenyl Phosphine Sulfide) obtained by the following formula.

  FIG. 2 shows the extraction rate measured under the same condition of excess amount of the extractant in comparison with the polymer bead type PTPPS.

  From FIG. 2, the extraction rate of the polymer bead type PTPPS was very slow, and the extraction rate of palladium was 40% even in 5 hours, whereas the extraction rate of the silica-supported PPVS was very fast and within 1 hour. The extraction rate was 100%.

Table 4 shows the extraction rate, back extraction rate, and repeated extraction rate of the polymer bead type PTPPS and silica-supported PPVS, respectively.

  The reverse extraction rate is obtained by removing the aqueous phase from the mixed system of extractant and solution after extraction, adding 3 ml of 1 molar uric acid (1 molar nitric acid solution) to the extractant, and stirring and dissolving at room temperature for 24 hours. The palladium concentration of the solution was measured and determined.

  The extraction ratio with respect to palladium was 100% for any of the extraction agents. Regarding the back extraction of palladium, the silica-supported PPVS was 100%, whereas the polymer bead type PTPPS was as low as about 77%.

  Table 4 also shows the results of repeated extraction in which the polymer-type extractant after back extraction was washed with nitric acid and then extracted again. This repeated extraction rate showed 100% for any extractant, and it was found that the extractant can be used repeatedly. The results shown in FIG. 2 and Table 4 are also described in Non-Patent Document 1.

  Table 5 shows the results of measuring the extraction rate of a solution containing ruthenium (Ru) and rhodium (Rh) as other platinum group elements under the same conditions for the same solid extractant.

  Thereby, it turns out that silica carrying type PPVS and polymer bead type PTPPS have high selectivity about palladium extraction.

As described above in detail, silica-supported PPVS carrying PPVS of silica polymeric extractant in carrying proportion ranging from 0.1% to 25% by weight, has excellent extraction characteristics, palladium It was found that this is an effective extractant.

  Silica-supported PPVS has a very high extraction rate compared to polymer bead type PTPPS, and both the back extraction rate and the repeat extraction rate are 100%, and it exhibits excellent selectivity for palladium. Therefore, it was also found that it is an optimum extractant for palladium.

  The polymer type extractant detailed above is described in Non-Patent Document 3, and the polymer bead type extractant and silica-supported polymer type extractant are described in Non-Patent Document 2.

Claims (3)

A method for preparing a solid extractant for use in extracting palladium from a solution, comprising:
Preparation of solid extractant, characterized in that silica gel is added to chloroform solution of polyphenyl vinyl sulfide and stirred overnight at room temperature, then the solvent is removed under vacuum to obtain silica gel loaded with polyphenyl vinyl sulfide. Method. A phenyl vinyl sulfide (monomer) produced by the substitution reaction of the following formula (1) and the elimination reaction of the following formula (2) is polymerized by the polymerization reaction of the following formula (3) to produce the polyphenyl vinyl sulfide. The method for preparing a solid extractant according to claim 1, wherein:

A method for extracting palladium, comprising bringing a solution into contact with the solid extractant prepared by the method according to claim 1 or 2 and extracting palladium from the solution.

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