KR950009706B1 - Method of preparing metal element adsorbent and method of adsorbing and separating metal - Google Patents

Abstract

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Description

Method for producing metal element adsorbent and method for adsorptive separation of metal elements by the adsorbent

1 is a graph showing the results of adsorption performance test example 1 according to the present invention.

2 is a graph showing the results of the adsorption performance test example 2 according to the present invention.

3 is a cross-sectional view of the column used in the adsorption performance test example 3 according to the present invention.

4 is a graph showing the uranium adsorption situation of adsorption performance test example 4 according to the present invention.

5 is a graph showing the uranium elution state of the adsorption performance test example 4 according to the present invention.

6 is a graph showing the results of adsorption performance test examples 7-9, 11, 13 and 14 of the present invention.

7 is a graph showing the results of the adsorption performance test 16 of the present invention.

The present invention is capable of adsorbing actinide such as uranium, thorium and ultra uranium, or heavy metal elements including cadmium, lead, chromium, mercury and iron, or metal elements such as cobalt, cesium and strontium. It relates to a method for producing a metal element adsorbent.

The present invention also relates to a method of adsorbing and separating a metal element from a solution containing the metal element using the adsorbent.

The waste luquid discharged from the nuclear fuel handling process contains nuclear fuel elements such as uranium and thorium.

DESCRIPTION OF RELATED ART Conventionally, as a manufacturing method of the adsorbent for adsorb | sucking this nuclear fuel element, the manufacturing method of the nuclear fuel element adsorbent which uses persimmon juice, ie, "nap juice" is disclosed (Japanese Patent Laid-Open No. 63-61998). Publication, Japanese Patent Laid-Open No. 1-155947).

This adsorbent is a hydrogel composition, and is prepared by reacting a liquid persimmon with an acid such as aldehyde or sulfuric acid or phosphoric acid to gel the persimmon.

On the other hand, the present applicant has previously applied for a method of dissolving tannin powder in an aldehyde aqueous solution, adding ammonia to this solution to form a precipitate, and aging the precipitate to prepare an adsorbent composed of insoluble tannin (Japanese Patent Laid-Open Application). 3-206094).

However, in the manufacturing method of the former hydrous gel composition, when a lot of tannins extracted from natural products other than persimmons are used as raw materials, the raw materials are limited to persimmons because they do not gelate even if aldehydes or acids are acted on these kinds of tannins. There was a problem.

Insoluble tannin prepared using the latter tannin powder is agglomerates of fine particles, and when it is filled into a column of the waste liquid treatment apparatus and passed through the waste liquid, the insoluble tannin is changed into the form of fine particles, and the liquid permeability of the column ( There is a problem of lowering the permeability.

Specifically, the adsorbent made of insoluble tannin had to be passed through at a space velocity of about 17 h ⁻¹ at most, and thus the waste liquid treatment ability could not be improved.

Accordingly, an object of the present invention is to produce a gel-like composition using a large number of condensed tannins present in a large amount in a natural state, having a high adsorption capacity, and in a column of a waste liquid treatment apparatus. The present invention provides a method for producing a metal element adsorbent having extremely good liquid permeability.

Another object of the present invention is to provide a method for adsorbing and separating a metal element which can recover the metal by efficiently adsorbing the metal element using the adsorbent.

The first method for obtaining the metal element adsorbent of the present invention is to dissolve condensed tannin powder in ammonia water, mix an aldehyde aqueous solution to this solution to form a gel composition, and to mature the gel composition at room temperature. Or stabilization by heating.

In the second method, ammonia water and an aldehyde aqueous solution are mixed, a condensed tannin powder is dissolved in the mixed solution, and the solution is heated to produce a stabilized gel composition.

The third method is a method in which a condensed tannin powder is dissolved in ammonia water of pH 8 or higher, hexamethylenetetramine is mixed with this solution, and the mixed solution is heated to produce a stabilized gel composition.

The fourth method is a gel composition in which a condensed tannin powder is mixed with an aqueous solution of hexamethylenetetramine, and ammonia water is added to the mixed solution to pH 8 or more to dissolve the condensed tannin powder, and the solution is heated and stabilized. How to create it.

In a fifth method, a condensed tannin powder is dissolved in an aqueous solution of an alkali metal hydroxide having a pH of 7-10, an aldehyde aqueous solution is mixed with this solution, and the mixed solution is heated to produce a stabilized gel composition.

In the sixth method, a condensed tannin powder is dissolved in an aqueous solution of an alkali metal hydroxide having a pH of 7-10, hexamethylenetetramine is mixed with the solution, and the mixed solution is heated to produce a stabilized gel composition. to be.

In the seventh method, the condensed tannin powder is mixed with an aqueous solution of hexamethylenetetramine, an alkali metal hydroxide is added to the mixed solution to pH 7-10, and the tannin powder described above is dissolved to heat the solution. To stabilize the gel composition.

In the present specification, "stabilization" of the gel composition refers to making the gel composition insoluble in any of water, acid or alkali, and "stabilized gel composition" is insoluble in any of water, acid or alkali. Refers to the composition.

According to the present invention, the metal element is adsorbed and separated from the solution containing the metal element by contacting the solution containing the metal element with the adsorbent of the present invention for a sufficient time so that the metal in the solution is adsorbed to the adsorbent. At this time, the adsorbent may be pre-ground to increase its surface area. After such a contact, the adsorbent which adsorb | sucked a metal element and the eluent, such as dilute mineral acid, for example, can be contacted, and a metal element can be collect | recovered from this adsorbent.

In particular, examples of the metal element that can be adsorbed by the adsorbent of the present invention include uranium, thorium, ultrauranium elements, heavy metals such as cadmium, lead, chromium, mercury and iron, or metal elements such as cobalt, cesium and strontium. Can be.

Suitable tannin powders for use in the methods of the invention are condensed tannins.

This condensed tannin means tannin that reacts with acid to produce anthocyanidin dyes. Such condensed tannins are extracted from quebracho, wattle, mangrove, spruce, gambier, acacatechin, oak bark, etc. Prepared by the conventional method of, does not contain persimmon.

As the aldehyde aqueous solution commonly used in the first, second and fifth methods, for example, formaldehyde aqueous solution, acetaldehyde aqueous solution, glutaraldehyde aqueous solution and the like can be cited. It is preferable because the production of the composition is accelerated and the mechanical strength of the gel composition is increased. As alkali metal hydroxides commonly used in the fifth, sixth and seventh methods, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like can be cited.

In the first method of the present invention, the mixing ratio of the condensed tannin powder, ammonia and aldehyde is 3-35% by weight of condensed tannin powder, 33-35% by weight of ammonia, and aldehyde based on the total amount of the three components. The range of 30-62 weight% is preferable. For example, when the tannin powder is 24% by weight, ammonia is 33% by weight and aldehyde is 43% by weight.

Of these mixing ratios, the ratio of condensed tannin powder is particularly important. If the tannin powder is less than 3% by weight, it is difficult to gel, and if it exceeds 35% by weight, the above-mentioned range is preferable.

This gel composition is not dissolved in water in this form but is soluble in acid or alkali. Therefore, the gel composition is preferably stabilized by the following two methods. One method is to leave the gel composition at room temperature of 20-25 ° C. for 3-4 days or more, and the other method is to quickly stabilize the gel composition by heating it. If the heating temperature is increased, the heating time can be shortened.

For example, heating at 70 ° C. requires at least 30 minutes to stabilize, but heating at 80 ° C. takes only 15 minutes.

In the second method, first, an aqueous ammonia solution and an aldehyde aqueous solution are mixed, and then the condensed tannin powder is dissolved in the mixed solution. The mixing ratio of this tannin powder, ammonia and aldehyde is the same as that shown in the first method.

After dissolving the tannin powder completely by stirring for about 5-10 minutes, the gel composition was stabilized by heating in the same manner as in the first method. That is, gelation and stabilization are performed simultaneously by this heating.

In the third method, first, the condensed tannin powder is dissolved in ammonia water of pH 8 or higher. If it is less than pH 8, it is because a tannin powder is hard to melt | dissolve in ammonia water. The mixing ratio of the condensed tannin powder depends on the pH of the ammonia water. For example, it is preferable to mix the tannin powder in the range of 1-15% by weight with respect to ammonia water at pH 8.

If the tannin powder is less than 1% by weight, the tannin powder is difficult to gel. When pH of ammonia water is made higher, the mixing amount of a tannin powder can be 15 weight% or more. Next, hexamethylenetetramine is added to ammonia water in which the tannin powder is dissolved, and mixed. This hexamethylenetetramine is mixed at least 0.5% by weight with respect to the aqueous ammonia solution in which the tannin powder is dissolved.

Next, the gel composition stabilized by heating similarly to the 2nd method is produced. In the fourth method, first, a condensed tannin powder is mixed with hexamethylenetetramine demand. The hexamethylenetetramine aqueous solution is an aqueous solution in which at least 0.5% by weight of hexamethylenetetramine is dissolved. This mixing ratio is the same as in the third method.

At this point, the tannin powder is not dissolved in the hexamethylenetetramine aqueous solution. However, when the pH 8 is 8 or more by adding ammonia water, the tannin powder is completely dissolved. Hereinafter, the gel composition stabilized by heating similarly to the 2nd and 3rd method is produced.

In the fifth method, first, a condensed tannin powder is dissolved in an aqueous solution of an alkali metal hydroxide having a pH of 7-10. It is because the tannin powder is hard to dissolve below pH 7, and when the pH exceeds 10, the gel composition produced is unstable and easily dissolved in water. The mixing ratio of the tannin powder is preferably mixed with the tannin powder in the range of 1-40% by weight based on the aqueous solution of the alkali metal hydroxide.

If the tannin powder is less than 1% by weight, the tannin powder is difficult to gel. If the tannin powder is more than 40% by weight, the viscosity of the mixed solution becomes high, making it difficult to handle. To this solution is mixed an aqueous aldehyde solution in the same manner as in the first method. As an aldehyde aqueous solution, when using the aqueous solution which contains 37 weight% of formaldehyde, for example, at least 1.39 ml of formaldehyde aqueous solution is added and mixed with respect to 50 ml of aqueous solutions which dissolve tannin.

Hereinafter, similarly to the second, third and fourth methods, this mixed solution is heated to produce a stabilized gel composition. In the sixth method, an aqueous solution of an alkali metal hydroxide is used instead of aqueous ammonia to produce a gel composition stabilized in the same manner as in the third method except that the pH is 7-10. The mixing ratio of tannin powder is the same as in the fifth method.

Hexamethylenetetramine (0.5% by weight) is mixed with an aqueous solution of alkali metal hydroxide in which tannin powder is dissolved. In the seventh method, an aqueous solution of an alkali metal hydroxide is used in place of aqueous ammonia, and a stabilized gel composition is produced in the same manner as in the fourth method except that the pH is 7-10. The mixing ratio of tannin powder is the same as in the fifth method.

By employing any of the seven methods of the present invention described above, the resulting gel composition is a metal element adsorbent that is insoluble in water, acid or alkali. The metal element adsorbent of the present invention may be crushed to a desired size by mechanical means such as a mixer in order to increase the contact area with the metal element-containing solution.

As a method of adsorbing and separating a metal element using this metal element adsorbent, a column method, a batch method, etc. can be mentioned.

The adsorbent of the present invention is packed into a column to adsorb a metal element, and then the dilute mineral acid is passed through the column to elute the metal element adsorbed to the adsorbent. In addition, the metal element can be eluted from the adsorbent by stirring the metal element in the adsorbent which adsorbed the metal element in the dilute acid. As dilute mineral acid, nitric acid, hydrochloric acid, sulfuric acid, etc. are used here.

As described above, according to the present invention, the condensed tannin powder used as the raw material of the adsorbent can utilize various tannins extracted from natural products other than persimmon, and thus, the effective use of resources can be achieved. Since it is inexpensive and easy to obtain, and becomes an adsorbent in a few steps, it is suitable for mass production and has a large economic effect.

Moreover, in this invention, the adsorbent excellent in the adsorption performance of a metal element is obtained by making many types of condensation tannin into a gel composition. When this adsorbent is subdivided into a desired size and filled in a column, a solution containing a metal element is passed through the column, which is extremely good in "liquidity" or "flow resistance" as compared with insoluble tannin made of conventional particulate aggregates. As a result, the processing capacity of the solution can be significantly improved.

In particular, the adsorbent obtained in the present invention is not only excellent in the adsorption performance of uranium, thorium and uranium generated in the nuclear fuel manufacturing process, but also the ultra uranium elements such as quirium, americium and nap generated in the nuclear fuel reprocessing process. It has excellent adsorption performance of various elements from heavy metal elements such as cadmium, lead, hexavalent chromium, mercury, iron, cobalt, cesium and strontium, which are produced in the process of handling tunium, plutonium or metal elements. Is extremely large. In addition, since the adsorbent of the present invention which adsorbs a metal can be incinerated without generating toxic gas, the volume of the adsorbent can be greatly reduced by incineration, thereby reducing the generation rate of solid waste.

In addition, depending on the metal element adsorbed, the solid material is made of a metal oxide containing no impurities, and can be reused.

In addition, the adsorbent obtained in the present invention has a high mechanical strength gel composition, so that the form is difficult to collapse even when contacted with a dilute acid, and the adsorbed metal element can be easily eluted from the gel composition to recover and purify the metal. . Hereinafter, the Example of this invention is demonstrated concretely with a comparative example. The following examples do not limit the scope of the invention.

Example 1

8 g of condensed tannin powder was added to 50 ml of 13.3N ammonia water to dissolve it, and then 57 ml of formaldehyde 37% by weight aqueous solution was added to the solution, followed by stirring and mixing. When this stirring was stopped, a gel composition was produced.

The gel composition was divided into two parts, one gel composition was left to mature at room temperature for 4 days, and the remaining gel composition was heated at 70 ° C for 1 hour. As a result, a metal element adsorbent composed of two stabilized gel compositions was obtained. In the adsorption performance test 1-14 described later, the latter metal element adsorbent was used.

Example 2

After mixing 50 ml of 13.3N ammonia water and 57 ml of 37% by weight aqueous formaldehyde solution, 8 g of Wattantan powder was added to the mixed solution to dissolve it, and the solution was heated at 70 ° C for 1 hour. As a result, gelation and stabilization were simultaneously performed to obtain a metal element adsorbent composed of the stabilized gel composition.

Example 3

8 g of Wattantan powder was added to 107 ml of ammonia water at pH 8.5 to dissolve. As the tannin powder was added, the pH of the solution gradually decreased, so that ammonia water was added at any time to maintain the pH of the solution at 8 or higher. Next, after adding 1.5 g of hexamethylenetetramine powder to this solution, it heated at 70 degreeC for 3 hours. As a result, gelation and stabilization were simultaneously performed to obtain a metal element adsorbent composed of the stabilized gel composition.

Example 4

To 107 ml of pure water, 1.5 g of hexamethylenetetramine powder was added and dissolved. Subsequently, 8 g of Wattle tannin powder was added to this aqueous solution and mixed uniformly. No tannin powder was dissolved at this stage. Next, ammonia water was added to this mixed solution, and the tannin was dissolved at a pH of the mixed solution of 8 or more, and then heated at 70 ° C. for 3 hours. As a result, gelation and stabilization were simultaneously performed to obtain a metal element adsorbent composed of the stabilized gel composition.

Example 5

8 g of Wattantan powder was added to 50 ml of an aqueous NaOH solution at pH 8.7 to dissolve. As the tannin powder is added, the pH of the solution gradually decreases, so that an aqueous NaoH solution is added at any time to maintain the pH of the solution.

Subsequently, after adding 2.77 ml of 37 weight% aqueous solution of formaldehyde to this solution, this solution was heated at 70 degreeC for 1 hour. As a result, gelation and stabilization were performed simultaneously, and a metal element adsorbent composed of the stabilized gel composition was obtained.

Example 6

8 g of wuttannin powder was added to 50 ml of an aqueous NaOH solution at pH 8.5 to dissolve it. As the tannin powder was added, the pH of the solution gradually decreased, so that an aqueous NaOH solution was added at any time to maintain the pH of the solution.

Next, 1.0 g of hexamethylenetetramine powder was added to this solution, followed by heating at 70 ° C. for 1 hour. As a result, gelation and stabilization were performed simultaneously, and a metal element adsorbent composed of the stabilized gel composition was obtained.

Example 7

1.0 g of hexamethylenetetramine powder was added to 50 ml of pure water to dissolve it. Subsequently, 8 g of tannin powder was added to this aqueous solution, and it mixed uniformly. At this stage, the tannin powder did not dissolve.

Next, an aqueous NaOH solution was added to the mixed solution, and the tannin was dissolved at a pH of the mixed solution of 7, followed by heating at 70 ° C for 1 hour.

As a result, gelation and stabilization were performed simultaneously, and a metal element adsorbent composed of the stabilized gel composition was obtained.

Comparative Example 1

8 g of Wattantan powder was dissolved in an aqueous 37% by weight formaldehyde solution. Subsequently, 14 ml or more of 13.7 N ammonia water was added to the solution to precipitate and filter the tannin compound, and the mixture was left at room temperature for 4 days to mature, to obtain a metal element adsorbent consisting of insoluble tannin having a particle size of about 1.0-2.4 mm.

[Adsorption performance test example 1]

The adsorbent obtained in Example 1-4 described above was crushed by a mixer so as to have the same particle size as the adsorbent of Comparative Example 1, subdivided into a particle size of about 1.0-2.4 mm, and then adsorption of uranium of Example 1-4 and Comparative Example 1 was carried out. The performance test was done.

A solution of pH 4 having a uranium concentration of 200 ppb was placed in five containers of 250 ml each. To these solutions, 25 mg of each of the metal element adsorbents obtained in Examples 1-4 and Comparative Example 1 were each added in dry weight, stirred for about 2 hours, and uranium was adsorbed to determine the adhesion rate.

Moreover, the adsorption rate of uranium was measured by changing with respect to the pH of the uranium containing solution of this test in various ways. In the adsorption test with the adsorbent obtained in Example 1-4, the pH was set to 6, 8 and 10. In the adsorption test with the adsorbent obtained in Comparative Example 1, the pH was set to 7 and 9.5, and the adsorption rate of uranium was measured in the same manner. It was. The results are shown in FIG.

Here adsorption rate α is, when the uranium concentration of the stock solution before addition of the adsorbent ₀ C, was added to the adsorbent the uranium concentration of the solution after adsorbing the uranium by C _t,

α = [(C ₀ -C _t ) / C ₀ ] × 100 (%)

Is the value calculated by.

As is apparent from FIG. 1, all the adsorbents of the gel composition of Example 1-4 exhibited high uranium adsorption rates in a wide range of pH 4-10, similarly to the adsorbents of the precipitate of Comparative Example 1. There was no difference in adsorption performance according to the form of.

[Adsorption performance test example 2]

The adsorbent obtained in Example 5-7 was crushed in a mixer and subdivided into particles having a particle diameter of about 1.0-2.4 mm, followed by an adsorption performance test of uranium. A solution of pH 4 having a uranium concentration of 245 ppb was placed in three containers of 250 ml each. 25 mg of each of the metal element adsorbents obtained in Example 5-7 was added to these solutions by dry weight, and stirred for about 2 hours to adsorb uranium, and the adsorption rate was measured. The result is shown in FIG.

As clearly shown in FIG. 2, all of the adsorbents consisting of the gel composition of Example 5-7 exhibited high uranium adsorption rates in a wide pH range.

[Adsorption performance test example 3]

The adsorbent obtained in Example 1 described above was subdivided into particle diameters of 1.0 to 2.4 mm, and then packed in the column 10 shown in FIG. The column 10 has an inner diameter of 50 mm, an inner diameter of the center portion 10b of 10 mm, an inner diameter of the outlet portion 10c of 4 mm, and a length from the upper end of the inlet portion to the lower portion of the center portion of 260 mm.

Glass wool 10d is loaded between the central portion 10b and the outlet portion 10c of the column 10. This adsorbent was filled until it became 180 mm from glass wool 10d. On the other hand, the adsorbent obtained in the comparative example 1 was equally packed in the column of the same structure.

In order to compare the liquid permeability of the column packed with the adsorbent of Example 1 and the column packed with the adsorbent of Comparative Example 1, 500 ml of pure water was injected into each column, and the passing time of 500 ml of the whole quantity was measured. This liquid test was carried out five times with different samples, and the results are shown in Table 1. As is apparent from Table 1, the average liquid passage time by the adsorbent of Example 1 was 0.85 hours while the average liquid passage time by the adsorbent of Comparative Example 1 was 4.88 hours.

This showed that Example 1 was about 5.7 times higher in liquid permeability than Comparative Example 1.

TABLE 1

(Unit: hour)

[Adsorption performance test example 4]

After dividing the adsorbent obtained in Example 1 into a particle diameter of 1.0-2.4 mm, a column having an inner diameter of 4 mm in the center portion was packed so as to have a height of 80 mm. The uranium concentration in the solution after the passage of the column was measured at regular time intervals while allowing a solution of pH 4 having a uranium concentration of 680 ppb to flow at a space velocity (SV) of 62.5 h ⁻¹ . The results are shown in FIG.

As can be seen from FIG. 4, the uranium concentration until about 2300 ml flowed became 1/10 or less of the uranium concentration of the stock solution. Since the volume of the adsorbent packed into the column is 1 ml (0.2 ² x pi x 0.8), the uranium-containing solution of about 2300 times or more of the volume of the adsorbent is treated, so that the adsorbent of Example 1 has high uranium adsorption performance. It was confirmed. In addition, 30-40mml of 0.1N nitric acid was added to the column packed with the adsorbent which adsorb | sucked this uranium at the ratio of 150 ml / h (linear velocity (LV) = 1190cm / h, space velocity (SV) = 149h- ¹ ). A total of 315 ml was flowed. The results are shown in Table 2 and FIG.

As shown in FIG. 5 and Table 2, as about 99% of uranium eluted from the column with 30 ml of the first dilute nitric acid, the uranium eluent concentration of the column gradually decreased, and finally nearly 100% of Uranium eluted. By this, it was confirmed that uranium elutes very easily from the adsorbent obtained in Example 1.

TABLE 2

[Adsorption performance test example 5]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example ³ , a solution having a thorium concentration of 8.5 × 10 ⁻¹ Bq / cm ³ was flowed through the same column as Test Example 3.

The thorium concentration in the solution was measured at the time of about 2300 ml of distillation from the column, and was 5.0 × 10 ⁺² Bq / cm ³ or less. It was confirmed from this that 94% or more of thorium was adsorbed to the adsorbent of Example 1.

[Adsorption performance test example 6]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 4 mg of the dry weight was collected and added to 1000 ml of natural seawater at pH 7.7 having a uranium concentration of 5.35 ppb. After stirring for 24 hours, uranium was adsorbed to this adsorbent.

This natural sea water was filtered through a filter paper (trade name: Toyo Filter Paper No. 6), and the concentration of uranium in the filtrate was 1.00 ppb. About 81% of uranium was adsorbed from this, and it was confirmed that the adsorption amount was 1088 µg per day per gram of adsorbent.

[Adsorption performance test example 7]

After subdividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 100 mg of the dry weight was collected, and a solution having a concentration of uranium element curium (244 cm) of 2.9 × 10 ⁻¹ Bq / cm ³ . To 200 ml. At this time, the curium-containing solution was prepared by changing the pH to four kinds from about 4 to about 10.

Each solution was stirred for 2 hours to adsorb curium to the adsorbent, and the adsorption rate was measured. The results are shown in FIG.

As is apparent from FIG. 6, this adsorbent showed a high adsorption rate in an acid solution.

[Adsorption performance test example 8]

After subdividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 100 mg of the dry weight was taken, and the concentration of americium (241Am), which is a superuranium element, was 1.6 × 1-0 ^-1 Bq / cm ³ . To 200 ml of solution was added. In this case, the americium-containing solution was prepared by changing the pH from about 3 to about 10 in six kinds.

Each solution was stirred for 2 hours to adsorb americium to the adsorbent, and the adsorption rate was measured. The results are shown in FIG.

As is apparent from FIG. 6, this adsorbent showed a higher adsorption rate as the solution became acidic.

[Adsorption performance test example 9]

After subdividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 100 mg of the dry weight was collected, and a solution having a concentration of Neptunium (237NP), which is a superuranium element, was 5.5 × 10 ⁻¹ Bq / cm ³ . To 200 ml. In this case, the neptunium-containing solution was prepared by changing the pH from four to about ten.

Each solution was stirred for 2 hours to adsorb neptunium to the adsorbent, and the adsorption rate was measured. The results are shown in FIG.

As is apparent from FIG. 6, this adsorbent showed a high adsorption rate at a pH of 6 or more.

[Adsorption performance test example 10]

After subdividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 25 mg was taken by dry weight, a solution of pH 6 having a plutonium concentration of 1.1 × 10 ⁻⁵ Bq / cm ^{3 as a} superuranium element. To 50 ml. The solution was stirred for 2 hours to adsorb plutonium to the adsorbent. This solution was filtrated and the plutonium concentration in the filtrate was 1.0 x 10 ^-6 Bq / cm ³ . It was confirmed from this that about 90% of plutonium was adsorbed.

[Adsorption performance test example 11]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 500 mg of the dry weight was collected and added to 250 ml of a solution having a cadmium concentration of 100 ppm, which is a metal element. At this time, the cadmium-containing solution was prepared by changing the pH to four kinds from about 4 to about 10.

Each solution was stirred for 3 hours to adsorb cadmium to the adsorbent, and the adsorption rate was measured. The results are shown in FIG.

As is apparent from FIG. 6, this adsorbent showed a higher adsorption rate as the solution became alkaline.

[Adsorption performance test example 12]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 250 mg of the dry weight was collected and added to 125 ml of a pH 6 solution having a lead concentration of 100 ppm, which is a metal element. The solution was stirred for 1 hour to adsorb lead to the adsorbent. This solution was filtered and the lead concentration in the filtrate was 8.1 ppm. From this, it was confirmed that about 92% of lead was adsorbed.

[Adsorption performance test example 13]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 250 mg of the dry weight was collected, and 125 ml of a solution of 100 ppm of hexavalent chromium (CrO ₃ ) containing a metal element as a component element. Added. At this time, the hexavalent chromium-containing solution was prepared by changing the pH from about 3.5 to about 10 in five kinds. The results are shown in FIG.

As is apparent from FIG. 6, this adsorbent showed a higher adsorption rate as the solution became acidic.

[Adsorption performance test example 14]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 250 mg was taken by dry weight and added to 125 ml of a solution having a concentration of 10 ppm of mercury as a metal element. At this time, the mercury-containing solution was prepared by changing the pH to four kinds from about 3.5 to about 10.

Each solution was stirred for 2 hours to adsorb mercury to the adsorbent, and the adsorption rate was measured. The results are shown in FIG.

As is apparent from FIG. 6, this adsorbent showed a high adsorption rate around 6 pH of the solution.

[Adsorption performance test example 15]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 250 mg of the dry weight was collected and added to 100 ml of a solution of pH 4 having a concentration of 1 ppm of iron as a metal element. The solution was stirred for 1 hour to adsorb iron to the adsorbent. The solution was filtered and the iron ion concentration in the filtrate was measured to be 0.01 ppm or less. From this, about 99% or more of iron ions were adsorbed, and the amount of adsorption was confirmed to be 495 μg or more per 1 g of the adsorbent.

[Adsorption performance test example 16]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 200 mg was taken by dry weight and added to 100 ml of a cobalt chloride (CoCl ₂ ) solution having a cobalt concentration of 100 ppm. At this time, the cobalt-containing solution was prepared by changing the pH to four kinds from about 4 to about 10.

Each solution was stirred for 3 hours to adsorb cobalt to the adsorbent, and the adsorption rate was measured. The result is shown in FIG.

As is apparent from FIG. 7, this adsorbent showed a higher adsorption rate as the solution became alkaline.

[Adsorption performance test example 17]

After subdividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 400 mg was collected by dry weight, and a strontium nitrate (Sr (NO ₃ ) ₂ ) solution having a strontium concentration of 100 ppm and a pH of 10. To 100 ml. The solution was stirred for 3 hours, strontium was adsorbed to the adsorbent, and the adsorption amount was determined. As a result, 16 mg of strontium per 1 g of adsorbent adsorbed, showing high adsorption performance.

[Adsorption performance test example 18]

After dividing the adsorbent obtained in Example 1 in the same manner as in Adsorption Performance Test Example 3, 400 mg was taken by dry weight and added to 100 ml of cesium nitrate (CaNO ₃ ) solution having a concentration of 10 ppm of cesium and pH 10. The solution was stirred for 3 hours to adsorb cesium to the adsorbent to determine the adsorption amount. As a result, 798 µg of cesium was adsorbed per 1 g of the adsorbent, thereby showing high adsorption performance.

Claims (26)

A method for producing a metal element adsorbent, comprising dissolving a condensed tannin powder in ammonia water, mixing an aqueous aldehyde solution with this solution to form a gel composition, and aging and stabilizing the gel composition. The method for preparing a metal element adsorbent according to claim 1, wherein the gel composition is left to mature at room temperature for a time sufficient to stabilize the gel composition. The method for producing a metal element adsorbent according to claim 2, wherein the gel composition is aged by heating at a temperature of room temperature or more for a time sufficient to stabilize the gel composition. A method for producing a metal element adsorbent, characterized by mixing ammonia water and an aldehyde aqueous solution, dissolving condensed tannin powder in the mixed solution and heating at a temperature above room temperature for a time sufficient to produce a gel composition having stabilized the solution. . A metal element characterized by dissolving condensed tannin powder in ammonia water of pH 8 or higher and mixing hexamethylenetetramine in this solution and heating at a temperature above room temperature for a time sufficient to produce a gel composition having stabilized the mixture. Process for preparing adsorbent. Condensed tannin powder is mixed with an aqueous solution of hexamethylenetetramine, and ammonia water is added to the mixed solution to pH 8 or above to dissolve the tannin powder as described above, and for a time sufficient to produce a gel composition having stabilized the solution. A method for producing a metal element adsorbent, characterized by heating at a temperature above room temperature. The condensed tannin powder is dissolved in an aqueous solution of an alkali metal hydroxide having a pH of 7-10, and an aqueous solution of aldehyde is mixed with the solution, and the mixture is added at a temperature above room temperature for a time sufficient to produce a stabilized gel composition. Method for producing a metal element adsorbent. Condensed tannin powder is dissolved in an aqueous solution of an alkali metal hydroxide having a pH of 7-10, and hexamethylenetetramine is mixed with the solution, and heated at a temperature above room temperature for a time sufficient to produce a gel composition having stabilized the mixture. Method for producing a metal element adsorbent, characterized in that. A condensed tannin powder is mixed with an aqueous solution of hexamethylenetetramine, an aqueous solution of an alkali metal hydroxide is added to the mixed solution to pH 7-10 to dissolve the tannin powder described above to produce a gel composition obtained by stabilizing this solution. Method for producing a metal element adsorbent, characterized in that heating at a temperature above room temperature for a sufficient time to. The method for producing a metal element adsorbent according to claim 7 or 8, wherein the alkali metal hydroxide described above is sodium hydroxide, potassium hydroxide or lithium hydroxide. It is obtained by the manufacturing method of Claim 1, The metal element adsorption agent characterized by the above-mentioned. It is obtained by the manufacturing method of Claim 2, The metal element adsorption agent characterized by the above-mentioned. It is obtained by the manufacturing method of Claim 3, The metal element adsorption agent characterized by the above-mentioned. It is obtained by the manufacturing method of Claim 4, The metal element adsorption agent characterized by the above-mentioned. A metal element adsorbent obtained by the production method according to claim 5. It is obtained by the manufacturing method of Claim 6. The metal element adsorption agent characterized by the above-mentioned. It is obtained by the manufacturing method of Claim 7, The metal element adsorption agent characterized by the above-mentioned. It is obtained by the manufacturing method of Claim 8. The metal element adsorption agent characterized by the above-mentioned. It is obtained by the manufacturing method of Claim 9. The metal element adsorption agent characterized by the above-mentioned. A solution containing a metal element and the metal element adsorbent according to claims 11 to 19 are brought into contact with each other for a sufficient time so that the metal in the solution is adsorbed to the adsorbent described above, and separated from the solution. Adsorption separation method of a metal element, characterized in that. 21. The method of claim 20 wherein the adsorbent described above is subdivided prior to contact with the electrolytic solution. The method of claim 20, wherein the contacting of the adsorbent described above with the solution is performed by filling the adsorbent described above into a tubular column and passing the solution described above through the column. 21. The method of claim 20, wherein said metal element is an actinium element. 21. The method of claim 20, wherein the metal element described above is an element selected from the group consisting of cadmium, lead, chromium, mercury, and iron. 21. The method of claim 20, wherein the metal element described above is an element selected from the group consisting of cobalt, cesium, and strontium. 21. The method of claim 20, wherein the separated adsorbent is contacted with a dilute acid to elute the metal element from the adsorbent.