KR102025087B1 - Hydrogel bead of removing radionuclide and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a hydrogel bead containing a polymer having a hydroxy group, wherein the hydrogel bead containing the magnetic nanoparticles and the radionuclide removal adsorbent, respectively, encapsulated inside the hydrogel bead, and a method for producing the same. It is about.

Description

Hydrogel bead for radionuclide removal and preparation method thereof {HYDROGEL BEAD OF REMOVING RADIONUCLIDE AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a hydrogel bead for radionuclide removal and a method for preparing the same.

Nuclear facilities, including nuclear power plants, as well as a variety of industries dealing with radionuclides generate a variety of radioactive waste. To treat such radioactive waste, adsorption, solvent extraction, chemical precipitation, membrane processing, coagulation, electrodialysis, ion exchange Various technologies are used industrially. Adsorption in the double is known as a simple and advantageous method for treating large amounts of radioactive waste. Adsorbents used for such adsorption may be various materials depending on the type of radionuclide. Specifically, for removing radioactive cesium, metal ion-ferrocyanide, zeolite, tetraphenylborate, ammonium phosphomolybdate, and the like, and for removing radioactive strontium, ferrous hydroxide (ferrous) hydroxide, calcium or iron phosphate, calcium carbonate, manganese dioxide, barium sulphate, and the like. In addition, there are various adsorbents for removing radionuclides such as Pu, Am, Cr-51, Mn-54, Co, Fe-59, Sb, Ru, Zr, Nb and Ce. On the other hand, it is well known that as the size of the adsorbents decreases, the surface area of the adsorbent increases, so that the adsorption motion of the adsorbent increases. Therefore, most of the studies related to the adsorbent are mainly focused on improving the adsorption performance by reducing the size of the adsorbent to micro or nano size. However, accordingly, there is a disadvantage in that various processes such as a centrifugal separation method and a membrane method are additionally required for recovery of the adsorbent after use.

Korean Patent Publication No. 10-1678860 (2016. 12. 06.)

The present invention is to provide a hydrogel bead, including a magnetic nanoparticles and radionuclide removal adsorbent, each encapsulated inside the hydrogel bead in a hydrogel bead comprising a polymer having a hydroxyl group, and the like. do.

However, the technical problem to be achieved by the present invention is not limited to the above-mentioned problem, another task that is not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention provides a hydrogel bead for removing a radionuclide comprising a magnetic nanoparticle and an adsorbent for removing radionuclides, each of which is encapsulated inside the hydrogel bead in a hydrogel bead including a polymer having a hydroxyl group.

In one embodiment of the invention, (a) preparing an aqueous solution containing a polymer having a hydroxyl group; And (b) adding a magnetic nanoparticle precursor to the aqueous solution prepared in step (a), and then preparing a solution in which an adsorbent for radionuclide removal is further added. To provide.

A radionuclide removing hydrogel bead containing a polymer having a hydroxyl group according to the present invention is prepared under a condition of pH 11.3 or more, and includes magnetic nanoparticles and an adsorbent for removing radionuclides, respectively, enclosed in the hydrogel beads. Characterized in that.

Therefore, according to the present invention, it can be usefully used to purify various radioactive waste liquids generated in various industries dealing with radionuclides as well as nuclear facilities including nuclear power plants, and various contaminated with radionuclides during serious accidents such as Fukushima nuclear accident. It can be effectively used to restore the water environment.

1 is a schematic diagram showing a hydrogel bead for radionuclide removal according to an embodiment of the present invention.
Figure 2 is a graph showing the XRD analysis of the hydrogel beads prepared in Examples 1-3.
3 is a photograph comparing the appearance of the hydrogel beads prepared in Examples 1 and 3 and the hydrogel beads prepared in Comparative Examples 1 to 3.
4 is a photograph showing the behavior of the hydrogel beads prepared in Example 1 when an external magnet is introduced into the hydrogel beads prepared in Example 1. FIG.
Figure 5 is a graph showing the results of confirming the adsorption performance for non-radioactive cesium using the hydrogel beads prepared in Example 1.

While the present inventors have studied hydrogel beads capable of maximizing the adsorption area of radionuclides, magnetic nanoparticles and radionuclide removal adsorbents are incorporated into hydrogel beads containing a polymer having a hydroxyl group at specific pH conditions. By encapsulating each, it was confirmed that radionuclides can be effectively removed, and the present invention was completed.

Hereinafter, the present invention will be described in detail.

Hydrogel Beads for Radionuclide Removal

The present invention provides a hydrogel bead for removing a radionuclide comprising a magnetic nanoparticle and an adsorbent for removing radionuclides, each of which is encapsulated inside the hydrogel bead in a hydrogel bead including a polymer having a hydroxyl group.

As used herein, the term "hydrogel" refers to a gel having water as a dispersion medium, and refers to a matrix of hydrophilic swellable three-dimensional structure that can be prepared by chemical and / or physical crosslinking of a specific polymer.

That is, the hydrogel is hydrophilic and can be easily hydrated in water. The hydrogel is contained in water while suppressing the release of magnetic nanoparticles and radionuclide removal adsorbents respectively enclosed in the hydrogel in water. The purified radionuclide may be introduced to purify the radioactive waste liquid.

As used herein, the term "bead" refers to grains of a size capable of maximizing an adsorption area, and may have an average particle size of several nm to several cm, preferably 100 nm to 1 cm, More preferably, it is 10 mm to 70 mm, but is not limited thereto.

1 is a schematic diagram showing a hydrogel bead for radionuclide removal according to an embodiment of the present invention.

As shown in Figure 1, the radionuclide for removing radionuclides according to an embodiment of the present invention in the hydrogel bead (10) comprising a polymer having a hydroxyl group, each inside the hydrogel bead (10) The encapsulated magnetic nanoparticles 20 and the radionuclide removal adsorbent 30 are included.

First, the radionuclide for removing radionuclides according to the present invention includes a polymer having a hydroxyl group.

The hydroxyl group in the polymer corresponds to a functional group that forms a hydrogen bond with the magnetic nanoparticles to be described later, and the hydrogen bond may form a crosslink having a network form between the polymer and the magnetic nanoparticle. In addition, the hydrogen bond is preferably made under a condition of pH 11.3 or more, which is a condition in which the magnetic nanoparticles described later are synthesized, but is not limited thereto.

Specifically, the polymer is preferably at least one selected from the group consisting of polyvinyl alcohol, gum arabic, guar gum, locust bean gum and derivatives thereof, and more preferably polyvinyl alcohol, but is not limited thereto. In addition, the polymer may include a diol group, a catechol group, or a salicylic hydroxy acid (Salicylhydroxamic acid) group.

In addition, the polymer may further include one or more materials selected from the group consisting of polyvinylpyrrolidone, cellulose, alginate, chitosan, polyacrylamide, polyacrylic acid, graphene oxide, graphite, and carbon nanotubes. At this time, in the case of a material having a skeleton containing a carboxyl group, such as alginate, polyacrylic acid, the carboxyl group may have an advantage of adsorbing radionuclides having positive charge in an anion state.

Next, the hydrogel beads for radionuclide removal according to the present invention include magnetic nanoparticles and radionuclide removal adsorbents respectively enclosed therein.

The magnetic nanoparticles are introduced for magnetic separation and recovery after radionuclide adsorption. It is characterized in that the encapsulated inside the hydrogel beads, it has the advantage of easy magnetic separation and recovery after radionuclide adsorption.

The magnetic nanoparticles to form a hydrogen bond with the hydroxyl group in the polymer, specifically, may be Fe ₃ O ₄ . Fe ₃ O ₄ can be synthesized through the following reaction.

^{Fe 2+ + 2Fe 3+ + 8OH -} → Fe 3 O 4 + 4H 2 O

At this time, the pH condition for synthesis is preferably at least pH 11.3, but is not limited thereto.

The radionuclide removing adsorbent is also encapsulated inside the hydrogel bead, wherein the radionuclide removing adsorbent is not outside the hydrogel bead through a crosslink having a mesh form between the polymer and the magnetic nanoparticles. By enclosed strongly in the inside, The radionuclide adsorbent can be easily prevented from leaking to the outside, and for the same reason, various radionuclide adsorbents are encapsulated inside the hydrogel beads to remove various nuclides simultaneously.

The radionuclide adsorbent for removal of Cs, Sr, Pu, Am. It may be for removing one or more radionuclides selected from the group consisting of Cr, Mn, Co, Fe, Sb, Ru, Zr, Nb and Ce, one type of radionuclide adsorbent is the hydrogel beads Although it may be enclosed inside, when the various kinds of radionuclide removal adsorbent is encapsulated inside the hydrogel bead, there is an advantage that can be removed at the same time.

The radionuclide removal adsorbent may be nano or micro sized.

For example, the radionuclide removal adsorbent may be an adsorbent for cesium removal, and is preferably a metal ion-ferrocyanide, but is not limited thereto. In this case, transition metal ions such as iron may be used as the metal ions, and sodium ferrocyanide (Na ₄ Fe (CN) ₆ ), potassium ferrocyanide (K ₄ Fe (CN) ₆ ) and ammonium ferrocyanide as ferrocyanide One or more selected from the group consisting of ((NH ₄ ) ₄ Fe (CN) ₆ ) can be used.

In the present invention, as the adsorbent for cesium removal, Prussian blue represented by the following Chemical Formula 1 was used:

[Formula 1]

.

.

At this time, Prussian blue represented by Formula 1 is a substance dissolved in water. On the other hand, Fe ^{4 +} [Fe (CN) ₆ ] ₃ may be used as the substance which does not dissolve in water.

Method for preparing hydrogel beads for radionuclide removal

The present invention (a) preparing an aqueous solution containing a polymer having a hydroxyl group; And (b) adding a magnetic nanoparticle precursor to the aqueous solution prepared in step (a), and then preparing a solution in which an adsorbent for radionuclide removal is further added. To provide.

(c) The solution prepared in step (b) may further comprise the step of preparing a hydrogel bead under the conditions of pH 11.3 or more.

First, the method for preparing a radionuclide for removing radionuclides according to the present invention includes the step [(a)] of preparing an aqueous solution containing a polymer having a hydroxyl group.

Since the polymer containing the hydroxyl group has been described above, duplicate descriptions will be omitted.

Next, the method for producing a radionuclide for removing radionuclides according to the present invention comprises adding a magnetic nanoparticle precursor to the prepared aqueous solution, and then preparing a solution to which an adsorbent for radionuclide removal is further added ((b)). Step].

The magnetic nanoparticle precursor refers to a starting material for synthesizing the magnetic nanoparticles, and may be FeCl ₃ and FeCl ₂ · 4H ₂ O as starting materials for synthesizing Fe ₃ O ₄ .

With respect to 100 parts by weight of the polymer, the added magnetic nanoparticle precursor is preferably 0.01 parts by weight to 200 parts by weight, but is not limited thereto. In this case, when the content of the added magnetic nanoparticle precursor is less than the above range, there is a problem in that the magnetic separation and recovery is not easy, and when the content of the added magnetic nanoparticle precursor exceeds the above range, it is encapsulated into the hydrogel bead. There is a problem that is not easy.

On the other hand, since the radionuclide removal adsorbent has been described above, duplicate description thereof will be omitted.

With respect to 100 parts by weight of the polymer, the added radionuclide removing adsorbent is preferably 0.01 parts by weight to 50 parts by weight, but is not limited thereto. At this time, when the content of the added radionuclide removal adsorbent is less than the above range, the radionuclide removal performance is insignificant, and when the content of the added radionuclide removal adsorbent exceeds the above range, it is encapsulated into the hydrogel beads. There is a problem that is not easy.

Next, the method for producing a radionuclide for removing a radionuclide according to the present invention further comprises the step [(c)] of preparing a hydrogel bead under the condition that the solution prepared in step (b) has a pH of 11.3 or more. It may include.

The preparation of the hydrogel beads may be carried out by dropping the prepared solution into an ammonium hydroxide solution, depending on the size of the droplets into which the prepared solution is dropped, the average particle size of the prepared hydrogel beads Can be adjusted. Specifically, the prepared solution may be added dropwise to the ammonium hydroxide solution using a pipette tip, wherein the average particle size of the hydrogel beads prepared is adjusted by adjusting the volume of the pipette tip to 0.1 mL to 20 mL. It can be adjusted from 10 mm to 70 mm.

In addition, the ammonium hydroxide solution to be used can maintain a condition of pH 11.3 or more, thereby well synthesizing the magnetic nanoparticles from the magnetic nanoparticle precursor, and then allowing the magnetic nanoparticles to form hydrogen bonds with hydroxyl groups in the polymer. It can be encapsulated inside the hydrogel beads without structural collapse of the radionuclide removal adsorbent.

At this time, when the pH of the ammonium hydroxide solution is less than 11.3, the cross-link having a mesh form between the polymer and the magnetic nanoparticles is not formed, the radionuclide adsorbent is not encapsulated inside the hydrogel beads, There is a problem that can not be released to form a stable hydrogel beads. On the other hand, when the metal ion-ferrocyanide (for example, Prussian blue represented by Formula 1) is used as the radionuclide adsorbent, when the pH of the ammonium hydroxide solution exceeds 11.5, the metal ion-ferrocyanide There is a problem that is dissolved.

Therefore, when the metal ion-ferrocyanide (for example, Prussian blue represented by Formula 1) is used as the radionuclide adsorbent, the pH of the ammonium hydroxide solution is maintained at 11.3 to 11.5, thereby reducing the radionuclide adsorbent. Stability can be secured.

The hydrogel beads for radionuclide removal may then be separated and recovered through a filter or external magnet after adsorbing the radionuclides. In this case, even if the radionuclide removing hydrogel beads have a small average particle size and are not easily separated and recovered through a filter, the magnetic nanoparticles encapsulated inside the hydrogel beads have superparamagnetism. Magnetic separation and recovery through external magnets is possible

As described above, the radionuclide removing hydrogel bead containing the polymer having a hydroxyl group according to the present invention was prepared under the conditions of pH 11.3 or more, respectively, the magnetic nanoparticles and radionuclides encapsulated inside the hydrogel beads. Characterized in that it comprises a removal adsorbent.

Therefore, according to the present invention, it can be usefully used to purify various radioactive waste liquids generated in various industries dealing with radionuclides as well as nuclear facilities including nuclear power plants, and various contaminated with radionuclides during serious accidents such as Fukushima nuclear accident. It can be effectively used to restore the water environment.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited by the following examples.

EXAMPLE

Example 1

500 g of polyvinyl alcohol (Mw = 138,000) was added to 10 ml of water, and stirred at 70 ° C. to prepare an aqueous solution. Here, FeCl ₃ 112 mg and 68 mg FeCl ₂ · H ₂ O were added. Then, a solution to which 50 mg of Prussian blue (Sigma Aldrich, Cas number = 12240-15-2) was added was prepared as an adsorbent for cesium removal.

Hydrogel beads were then prepared by dropping the solution into 20 mL of ammonium hydroxide (NH ₄ OH) solution adjusted to pH 11.3 using a commercially available 0.2 mL volume pipette tip. At this time, the average particle size (15 average values) of the prepared hydrogel beads is about 33.8 mm.

Example 2

Hydrogel beads were prepared in the same manner as in Example 1 except that the pH of the ammonium hydroxide (NH ₄ OH) solution was adjusted to 11.4.

Example 3

Hydrogel beads were prepared in the same manner as in Example 1 except that the pH of the ammonium hydroxide (NH ₄ OH) solution was adjusted to 11.5.

Example 4

Hydrogel beads were prepared in the same manner as in Example 1, except that the volume of the pipette tip was changed to 1 mL. At this time, the average particle size (15 average values) of the prepared hydrogel beads is about 38.0 mm.

Example 5

Hydrogel beads were prepared in the same manner as in Example 1, except that the volume of the pipette tip was changed to 5 mL. At this time, the average particle size (15 average values) of the prepared hydrogel beads is about 42.3 mm.

Example 6

Hydrogel beads were prepared in the same manner as in Example 1, except that the volume of the pipette tip was changed to 10 mL. At this time, the average particle size (15 average values) of the prepared hydrogel beads is about 53.0 mm.

Comparative Example 1

Hydrogel beads were prepared in the same manner as in Example 1 except that the pH of the ammonium hydroxide (NH ₄ OH) solution was adjusted to 10.9.

Comparative Example 2

Hydrogel beads were prepared in the same manner as in Example 1 except that the pH of the ammonium hydroxide (NH ₄ OH) solution was adjusted to 11.0.

Comparative Example 3

Hydrogel beads were prepared in the same manner as in Example 1 except that the pH of the ammonium hydroxide (NH ₄ OH) solution was adjusted to 11.2.

Figure 2 is a graph showing the XRD analysis of the hydrogel beads prepared in Examples 1-3.

As shown in Figure 2, the beads prepared in Examples 1 to 3 were all confirmed to show peaks at the same position as the characteristic peaks of Fe ₃ O ₄ (red vertical line) and Prussian blue (blue vertical line). It was confirmed that Fe ₃ O ₄ was well synthesized and that Prussian blue was well encapsulated inside the hydrogel beads without structural collapse.

3 is a photograph comparing the appearance of the hydrogel beads prepared in Examples 1 and 3 and the hydrogel beads prepared in Comparative Examples 1 to 3.

As shown in FIG. 3, according to Examples 1 and 3, it was confirmed that the hydrogel beads were stably formed, but according to Comparative Examples 1 to 3, crosslinking in the form of a mesh was formed between polyvinyl alcohol and Fe ₃ O _4. In the absence of formation, the radionuclide removal adsorbent is not encapsulated inside the hydrogel beads, but is released out and observed as a brownish solution.

In other words, when prepared under a condition of pH 11.3 or more, a stable hydrogel bead is formed, but when prepared under a condition of pH 11.2 or less, a radionuclide removing adsorbent is not encapsulated inside the hydrogel bead, but released out to provide a stable hydrogel bead. It can be seen that it is not formed.

4 is a photograph showing the behavior of the hydrogel beads prepared in Example 1 when an external magnet is introduced into the hydrogel beads prepared in Example 1. FIG.

As shown in FIG. 4, the magnetic nanoparticles encapsulated inside the hydrogel beads prepared in Example 1 have superparamagnetism, and are manufactured in Example 1 by magnetizing the magnetic nanoparticles due to an external magnetic field of an external magnet. It can be seen that the hydrogel beads can be moved toward the outer magnet, which can be easily magnetically separated and recovered.

Figure 5 is a graph showing the results of confirming the adsorption performance for non-radioactive cesium using the hydrogel beads prepared in Example 1.

As shown in FIG. 5, the adsorption performance for non-radioactive cesium using the hydrogel beads prepared in Example 1 was found to conform well with the langmuir isotherm model. At this time, the maximum adsorption amount (Q _max ) for the non-radioactive cesium is confirmed to be about 13.6 mg / g.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (11)

In a hydrogel bead containing a polymer having a hydroxyl group,
Including the magnetic nanoparticles and radionuclide removal adsorbent, respectively enclosed in the hydrogel beads,
The magnetic nanoparticles form a hydrogen bond with a hydroxyl group in the polymer, thereby forming a crosslink having a network form between the polymer and the magnetic nanoparticles.
Hydrogel beads for radionuclide removal.
The method of claim 1,
The average particle size of the hydrogel beads is 100 nm to 1 cm
Hydrogel beads for radionuclide removal.
The method of claim 1,
The polymer having a hydroxy group is at least one selected from the group consisting of polyvinyl alcohol, gum arabic, guar gum, locust bean gum and derivatives thereof
Hydrogel beads for radionuclide removal.
delete The method of claim 1,
The magnetic nanoparticles are Fe ₃ O ₄
Hydrogel beads for radionuclide removal.
The method of claim 1,
The radionuclide adsorbent for removal of Cs, Sr, Pu, Am. For removing one or more radionuclides selected from the group consisting of Cr, Mn, Co, Fe, Sb, Ru, Zr, Nb and Ce
Hydrogel beads for radionuclide removal.
(a) preparing an aqueous solution containing a polymer having a hydroxyl group;
(b) adding a magnetic nanoparticle precursor to the aqueous solution prepared in step (a), and then preparing a solution in which an adsorbent for radionuclide removal is further added; And
(c) preparing the hydrogel beads under the conditions of pH 11.3 or higher using the solution prepared in step (b).
Method for producing a hydrogel beads for radionuclide removal according to claim 1.
delete The method of claim 7, wherein
The magnetic nanoparticle precursor added in the step (b) is 0.01 parts by weight to 200 parts by weight based on 100 parts by weight of the polymer in step (a), and the radionuclide removal adsorbent added in the step (b) is 0.005 To 50 parts by weight
Method of producing hydrogel beads for radionuclide removal.
The method of claim 7, wherein
The magnetic nanoparticle precursor added in step (b) is FeCl ₃ and FeCl ₂ · 4H ₂ O
Method of producing hydrogel beads for radionuclide removal.
The method of claim 7, wherein
Preparation of the hydrogel beads in step (c) is carried out by dropping the solution prepared in step (b) to the ammonium hydroxide solution
Method of producing hydrogel beads for radionuclide removal.

Images