JP5750388B2 - Method for removing radioactive iodine and radioactive cesium and hydrophilic resin composition for removing radioactive iodine and radioactive cesium - Google Patents

Description

  The present invention relates to a method for removing both radioactive iodine and radioactive cesium in radioactive liquid waste and / or radioactive solids generated from nuclear power plants and spent nuclear fuel facilities, and radioiodine / radioactive cesium suitable for carrying out the method. It is related with the hydrophilic resin composition which shows the function to fix all.

Currently, widely used nuclear power plants involve the production of significant amounts of radioactive by-products due to nuclear fission in the reactor. The main ones of these radioactive materials are fission products and active elements containing extremely dangerous radioactive isotopes such as radioactive iodine, radioactive cesium, radioactive strontium and radioactive cerium. Among these, since radioactive iodine becomes a gas at 184 ° C, it is very likely to be released when inspecting and replacing nuclear fuel, and for other reasons such as accidents when handling nuclear fuel and accidents such as reactor runaway accidents. There is a danger. The main radioactive iodines are iodine with a long half-life of 129 (half-life: 1.57 × 10 ⁷ years) and iodine with a short half-life of 131 (half-life: 8.05 days). Here, normal iodine that does not exhibit radioactivity is a trace element essential for the human body, and is collected in the thyroid gland near the throat and becomes a component of growth hormone. For this reason, when humans take in radioactive iodine through breathing, water, and food, they are collected in the thyroid gland just like normal iodine, increasing internal radiation exposure. There must be.

  In addition, radioactive cesium is one of metals that have a melting point of 28.4 ° C. and is in a liquid state at around room temperature, and is very easily released like radioactive iodine. The target radioactive cesium is mainly cesium 134 having a relatively short half-life (half-life: 2 years) and cesium 137 having a long half-life (half-life: 30 years). In particular, cesium 137 not only has a long half-life, but also emits high-energy radiation and has a property of being highly soluble in water because it is an alkali metal. Furthermore, since radioactive cesium is easily absorbed by the human body through breathing and skin, and is dispersed almost uniformly throughout the body, human health damage is serious.

  For this reason, when radioactive cesium is accidentally released from reactors operating around the world due to unforeseen reasons, not only radioactive contamination to workers working in the reactor and neighboring residents, but also due to air There is concern that a wider range of radioactive contamination will be caused to humans and animals through food and water contaminated by the radioactive cesium being carried. The danger in this regard has been clearly demonstrated by the Chernobyl nuclear power plant accident.

  In response to such a situation, as a method for treating radioactive iodine generated in a nuclear reactor, a cleaning treatment method, a physical / chemical treatment method using solid adsorbent filling using fibrous activated carbon or the like (see Patent Documents 1 and 2) ), Treatment with an ion exchange agent (see Patent Document 3) and the like have been studied.

  However, any of the above-described methods has problems as described below, and development of a method for removing radioactive iodine in which these problems are solved is desired. First, there are alkali cleaning methods and the like that have been put to practical use in the cleaning treatment method. However, in order to treat this in a liquid adsorption agent cleaning method and store it in a liquid state for a long period of time, it is quantitative. There are also many safety issues. In addition, in the physical / chemical treatment method using solid adsorbent filling, the trapped iodine is always exposed to the possibility of exchange with other gases, and the adsorbate is easily released when the temperature rises. There are difficulties. Furthermore, in the treatment system using an ion exchanger, the heat resistant temperature of the ion exchanger is up to about 100 ° C., and there is a problem that sufficient performance cannot be exhibited at a temperature higher than this.

  On the other hand, as a method for treating radioactive cesium produced in a nuclear reactor, an adsorption method using an inorganic ion exchanger or a selective ion exchange resin, a coprecipitation method using a heavy metal and a soluble ferrocyanide or a ferrocyanide salt in combination, a cesium precipitation reagent There is known a chemical treatment method by the method (see Patent Document 4).

  However, all of the above-described processing methods require large-scale equipment such as a circulation pump, a septic tank, and a filling tank containing each adsorbent, and further, a large amount of energy is required to operate them. In addition, as the Fukushima Daiichi nuclear power plant accident in Japan on March 11, 2011, when the power supply was cut off, these facilities would not be able to operate, so contamination with radioactive iodine, radioactive cesium, etc. The risk level of increases. And especially when the power supply is cut off, the removal method for radioactive iodine and radioactive cesium diffused in the surrounding area due to the runaway accident of the reactor falls into a very difficult situation, and the radioactive contamination may be expanded. There is a concern that the situation will not be. Accordingly, there is an urgent need to develop a technique for removing radioactive iodine and radioactive cesium that can cope with such a situation. In addition, it would be extremely useful if an effective removal technique capable of treating radioactive iodine and radioactive cesium together was developed.

Japanese Patent Publication No.62-44239 JP 2008-116280 A JP 2005-37133 A JP-A-4-118596

  Accordingly, an object of the present invention is to solve the problems of the prior art in providing an effective removal technique capable of treating radioactive iodine and radioactive cesium together, and to reduce energy consumption such as electric power easily and at low cost. It is not necessary, and it can be fixed by taking in the removed radioactive iodine and radioactive cesium inside the solid, and can be fixed more stably, and the volume of radioactive waste can be reduced as needed. The object is to provide a technology for removing radioactive iodine and radioactive cesium. Since the object of the present invention has a function capable of immobilizing both radioactive iodine and radioactive cesium, which is particularly useful when implementing the above-described technique, it is possible to remove these radioactive substances together. The object is to provide a novel hydrophilic resin composition.

The above object is achieved by the present invention described below.
That is, the present invention relates to a method for removing radioactive iodine / radioactive cesium using a hydrophilic resin composition comprising a hydrophilic resin and a ferrocyanide compound that removes radioactive iodine / radioactive cesium in radioactive liquid waste and / or radioactive solids. The hydrophilic resin has a hydrophilic segment and has a hydrophilic group in the molecule, but is insoluble in water and warm water, and has a main chain in the structure. And / or at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin and a hydrophilic polyurethane-polyurea resin having a tertiary amino group and a polysiloxane segment in the side chain, and the above In the hydrophilic resin composition, at least the ferrocyanide compound is dispersed at a ratio of 1 to 200 parts by mass with respect to 100 parts by mass of the hydrophilic resin. Wherein the by comprising Te provides method of removing radioactive iodine, radioactive cesium.

The following are mentioned as a preferable form of this invention. The hydrophilic segment is a polyethylene oxide segment. The hydrophilic resin comprises a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group, at least one active hydrogen group and a polysiloxane segment in the same molecule. It is a resin formed using a compound having a part of the raw material. The ferrocyanide metal compound is a compound represented by the following general formula (1).
_{A x M y [Fe (CN} ) 6] (1)
[Wherein, A is any one selected from K, Na, and NH ₄ , M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, and x, y Satisfies the formula x + ny = 4 (x is a number from 0 to 3), and n represents the valence of M. ]

In another aspect of the present invention, there is provided a hydrophilic resin composition having a function capable of fixing both radioactive iodine and radioactive cesium in a liquid and / or a solid material, the hydrophilic resin and a ferrocyanide metal. And a hydrophilic resin comprising a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group, at least one active hydrogen-containing group, and a polysiloxane segment And having a hydrophilic segment in the molecule, and having a tertiary segment in the molecular chain and a polysiloxane segment . It has the group, an insoluble resin in water and hot water, and, with respect to 100 parts by weight of the hydrophilic resin, at least, ferrocyanide metal compound 1-2 To provide a hydrophilic resin composition for removing radioactive iodine, radioactive cesium, characterized in that is dispersed in a proportion of 0 part by weight.

Furthermore, in another aspect of the present invention, as another embodiment, a hydrophilic resin composition having a function capable of fixing both radioactive iodine and radioactive cesium in a liquid and / or a solid substance, the hydrophilic resin and ferrocyanated And a hydrophilic compound comprising an organic polyisocyanate, a high molecular weight hydrophilic polyol and / or polyamine which is a hydrophilic component, at least one active hydrogen-containing group and at least one tertiary. A molecule having a hydrophilic segment obtained by reacting a compound having an amino group in the same molecule with a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule; It has the hydrophilic group in a insoluble resin to water and hot water, and tertiary amino groups and polysiloxane cell in the main chain and / or side chain in the structure And at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin and a hydrophilic polyurethane-polyurea resin, and at least ferrocyan with respect to 100 parts by mass of the hydrophilic resin. Provided is a hydrophilic resin composition for removing radioactive iodine and radioactive cesium, characterized in that the metal halide compound is dispersed at a ratio of 1 to 200 parts by mass.

The following is mentioned as a preferable form of one of the above-described hydrophilic resin compositions of the present invention. The hydrophilic segment of the hydrophilic resin is a polyethylene oxide segment. The ferrocyanide metal compound is a compound represented by the following general formula (1).
_{A x M y [Fe (CN} ) 6] (1)
[Wherein, A is any one selected from K, Na, and NH ₄ , M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, and x, y Satisfies the formula x + ny = 4 (x is a number from 0 to 3), and n represents the valence of M. ]

According to the present invention, radioactive iodine and radioactive cesium present in waste liquid and waste solids can be removed easily and at low cost, and without the need for an energy source such as electric power, and removed. cesium was fixing Nde Captures inside solid, more stably can be immobilized, volume reduction of radioactive waste as required are also possible, moreover be removed handle radioactive iodine and radioactive cesium together New technology is provided. According to the present invention, it has a function capable of immobilizing both radioactive iodine and radioactive cesium, and it can be realized to remove them together, and the main component is a resin composition. A novel hydrophilic resin composition capable of reducing the volume of radioactive waste as required is provided. These remarkable effects of the present invention are because the hydrophilic resin has in its structure a hydrophilic segment, at least one tertiary amino group and a polysiloxane segment in the molecular chain. More specifically, the organic polyisocyanate, the high molecular weight hydrophilic polyol and / or polyamine (hereinafter referred to as “hydrophilic component”), at least one active hydrogen-containing group and at least one tertiary amino group are the same. From a hydrophilic polyurethane resin, a hydrophilic polyurea resin, a hydrophilic polyurethane-polyurea resin obtained by reacting a compound having in the molecule and a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule. Hydrophilic property obtained by dispersing a ferrocyanide metal compound in at least one hydrophilic resin selected from the group consisting of It is achieved in a very simple method of utilizing fat composition.

The figure which shows the relationship between the iodine concentration in aqueous solution, and the immersion time of the film produced with the hydrophilic resin composition of Examples 1-3. The figure which shows the relationship between the cesium density | concentration in aqueous solution, and the immersion time of the film produced with the hydrophilic resin composition of Examples 1-3. The figure which shows the relationship between the iodine concentration in aqueous solution, and the immersion time of the film produced with the non-hydrophilic resin composition of Comparative Examples 1-2. The figure which shows the relationship between the cesium density | concentration in aqueous solution, and the immersion time of the film produced with the non-hydrophilic resin composition of Comparative Examples 1-2.

Next, the present invention will be described in more detail with reference to preferred embodiments.
The hydrophilic resin composition characterizing the present invention is a composition in which a ferrocyanide compound represented by bitumen is dispersed in a hydrophilic resin, and the hydrophilic resin comprises a hydrophilic component as a constituent unit. A hydrophilic segment, a tertiary amino group-containing segment having a component having a tertiary amino group as a constituent unit, and a polysiloxane segment in the main chain and / or side chain in the structure. Features. That is, the hydrophilic resin used in the present invention is a tertiary resin having a hydrophilic segment as a structural unit and a component having at least one tertiary amino group as a structural unit in the structure. What is necessary is just to have an amino group containing segment and a polysiloxane segment. When a chain extender is not used during the synthesis of the hydrophilic resin, these segments are bonded at random by a urethane bond, a urea bond, a urethane-urea bond, or the like. When chain extension is used during the synthesis of the hydrophilic resin, a short chain which is a residue of the chain extender exists between these bonds in addition to the above bonds.

  “Hydrophilic resin” in the present invention means a resin having a hydrophilic group in its molecule but insoluble in water, hot water, etc., and includes polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylic acid. And water-soluble resins such as cellulose derivatives.

  The hydrophilic resin composition of the present invention comprises a hydrophilic resin and a ferrocyanide metal compound typified by bitumen. By using the hydrophilic resin composition, radioactive iodine and radioactive cesium are removed together. Processing becomes possible. The present inventors consider the reason as follows. First, the hydrophilic resin used in the present invention exhibits excellent water absorption by the hydrophilic segment, and further, by introducing tertiary amino groups in the main chain and / or side chain in the structure. It is considered that an ionic bond is formed between the ionized radioactive iodine and as a result, the radioactive iodine is fixed in the hydrophilic resin.

  However, since the ionic bonds as described above are easily dissociated in the presence of moisture, it is considered that radioactive iodine is released from the resin again after a certain period of time, and the present inventors determined the state of fixation of radioactive iodine in the resin. It was expected that it would be difficult to remove in a fixed state. However, contrary to this expectation, it was actually found that ion-bound radioactive iodine remained fixed in the resin even when standing for a long time. The reason for this is not clear, but the present inventors consider as follows. That is, the hydrophilic resin having a specific structure used in the present invention also has a hydrophobic portion in the molecule, and an ionic bond was formed between the tertiary amino group in the resin and radioactive iodine. Later, it is presumed that this hydrophobic part may surround the hydrophilic part (hydrophilic segment) and the ion binding part. For these reasons, in the present invention, radioactive iodine can be fixed to the resin and removed by using the hydrophilic resin composition of the present invention including a hydrophilic resin having a specific structure. it is conceivable that.

  The hydrophilic resin used in the present invention further needs to have a polysiloxane segment in its structure. Here, the polysiloxane segment introduced into the resin molecule is inherently hydrophobic (water repellency). However, when a specific amount of polysiloxane segment is introduced into the structure, the resin is “environmental responsiveness”. It is known that there will be a property "(Polymer Journal, Vol. 48 [No. 4], 227 (1991)). The resin referred to in the above paper has “environmental responsiveness”. In the dry state, the resin surface is completely covered with the polysiloxane segment. However, when the resin is immersed in water, the polysiloxane segment is in the resin. It is a phenomenon that is buried in

  In the present invention, this “environmental responsiveness” phenomenon that appears in a resin by introducing a polysiloxane segment is used for the removal treatment of radioactive iodine. As described above, when an ionic bond is formed between the tertiary amino group introduced into the hydrophilic resin used in the present invention and the radioactive iodine to be treated, the resin further increases in hydrophilicity. However, this may cause the following problems. That is, in the method for removing radioactive iodine and radioactive cesium of the present invention, as described later, in order to fix and remove radioactive iodine and radioactive cesium, for example, a hydrophilic resin is used in the form of a film or the like. In this case, if the amount of radioactive iodine to be treated is large, the water resistance required for the resin may be hindered. On the other hand, in the present invention, by introducing a polysiloxane segment further into the molecule (structure) of the hydrophilic resin to be used, the resin to be used has a sufficient water resistance function even in the above case. This realizes a resin configuration in which the processing is effectively performed. That is, the hydrophilic resin characterizing the present invention is introduced into the structure by introducing the polysiloxane segment in addition to the water absorption performance by the hydrophilic segment and the fixing performance to the radioactive iodine by the tertiary amino group. By realizing the water resistance of the resin and the blocking resistance (sticking resistance) of the surface, it becomes more useful when used for the removal treatment of radioactive iodine.

Furthermore, in the present invention, by using the hydrophilic resin composition of the present invention containing a ferrocyanide metal compound typified by bitumen, it is possible to remove radioactive cesium in addition to the above-described removal of radioactive iodine. This achieved the treatment of radioactive iodine and radioactive cesium together. The ferrocyanide compound used in the present invention is a compound represented by the following general formula (1). Some of these are called bitumen and are widely used as coloring materials, and any of them can be suitably used in the present invention.
_{A x M y [Fe (CN} ) 6] (1)
[Wherein, A is any one selected from K, Na, and NH ₄ , M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, and x, y Satisfies the formula x + ny = 4 (x is a number from 0 to 3), and n represents the valence of M. ]

More specific examples of the ferrocyanide compound include compounds represented by the following general formula (A) or (B) called bitumen, and these are pigments produced from a long time ago. There are many common names such as Prussian blue, Milori blue and Berlin blue.
MFe [Fe (CN) ₆ ] (A) [However, M = NH ₄ , K, Fe]
MK ₂ [Fe (CN) ₆ ] (B) [However, M = Ni, Co]

  The use of bitumen as described above for the removal of radioactive cesium is already known and is actually used in the event of the Chernobyl nuclear power plant accident. The mechanism of bitumen's removal of radioactive cesium has not yet been fully elucidated, but the following two ideas have been proposed: “ion exchange” and “adsorption”.

  The idea of “ion exchange” is that when ammonium bitumen, which is a kind of bitumen, contacts with cesium ions, the cation and cesium ions in the bitumen are replaced by ion exchange, and radioactive cesium is fixed and can be removed. . On the other hand, “adsorption” is an idea that cesium ions are selectively adsorbed in vacancies having a bitumen crystal interval of about 0.5 nm, and as a result, radioactive cesium is removed. At present, it is not clear which is correct, but in any case, the effect of removing cesium by bitumen has been demonstrated. The metal ferrocyanide compound represented by bitumen capable of removing such radioactive cesium is dispersed in a hydrophilic resin having a unique structure capable of removing the above-mentioned radioactive iodine. By using the hydrophilic resin composition, the present invention provides a technique capable of removing radioactive iodine and radioactive cesium together.

  Next, the raw material for forming the hydrophilic resin characterizing the present invention that achieves the above-described performance will be described. The hydrophilic resin used in the present invention is characterized by having a hydrophilic segment, a tertiary amino group, and a polysiloxane segment in its structure. Therefore, in order to obtain the hydrophilic resin, a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group, at least one active hydrogen-containing group, and a polysiloxane segment are used. It is preferable to use as a part of the raw material a compound having As the compound for introducing a tertiary amino group into the hydrophilic resin used in the present invention, it is preferable to use a tertiary amino group-containing compound as described below. That is, as the at least one active hydrogen-containing group (hereinafter sometimes referred to as a reactive group) in the molecule, for example, an amino group, an epoxy group, a hydroxyl group, a mercapto group, an acid halide group, a carboxyester group, an acid A compound having an anhydride group or the like and a tertiary amino group in the molecular chain is used.

［式（２）中の、Ｒ₁は炭素数２０以下のアルキル基、脂環族基、又は芳香族基（ハロゲン、アルキル基で置換されていてもよい）であり、Ｒ₂及びＲ₃はそれぞれ独立に、−Ｏ−、−ＣＯ−、−ＣＯＯ−、−ＮＨＣＯ−、−Ｓ−、−ＳＯ−、−ＳＯ₂−等で連結されていてもよい低級アルキレン基であり、Ｘ及びＹは−ＯＨ、−ＣＯＯＨ、−ＮＨ₂、−ＮＨＲ₁（Ｒ₁は上記と同じ定義である）、−ＳＨ等の反応性基であり、Ｘ及びＹは同一でも異なってもよい。又、Ｘ及びＹは上記の反応性基に誘導できるエポキシ基、アルコキシ基、酸ハライド基、酸無水物基、又はカルボキシルエステル基でもよい。］ Preferable specific examples of the tertiary amino group-containing compound having a reactive group as described above include compounds represented by the following general formulas (2) to (4).

[In Formula (2), R ₁ is an alkyl group having 20 or less carbon atoms, an alicyclic group, or an aromatic group (which may be substituted with a halogen or an alkyl group), and R ₂ and R ₃ are independently, -O -, - CO -, - COO -, - NHCO -, - S -, - SO -, - SO 2 - is a substituted lower alkylene group which may be coupled with such, X and Y It is a reactive group such as —OH, —COOH, —NH ₂ , —NHR ₁ (R ₁ has the same definition as above), —SH, and X and Y may be the same or different. X and Y may be an epoxy group, an alkoxy group, an acid halide group, an acid anhydride group, or a carboxyl ester group that can be derived from the above reactive group. ]

［式（３）中の、Ｒ₁、Ｒ₂、Ｒ₃、Ｘ及びＹは、前記式（２）におけるものと同じ定義であるが、但し二つのＲ₁同士は環状構造を形成するものであってもよい。Ｒ₄は−(ＣＨ₂)_n−、（ｎは０〜２０の整数）である。］

[In formula (3), R ₁ , R ₂ , R ₃ , X and Y have the same definition as in formula (2), except that two R ₁ form a cyclic structure. There may be. R ₄ is — (CH ₂ ) _n —, where n is an integer of 0-20. ]

（式（４）中の、Ｘ及びＹは、前記式（２）におけるものの定義と同じであり、Ｗは、窒素含有複素環、窒素と酸素含有複素環、又は窒素と硫黄含有複素環を表す。）

(X and Y in the formula (4) are the same as defined in the formula (2), and W represents a nitrogen-containing heterocyclic ring, a nitrogen and oxygen-containing heterocyclic ring, or a nitrogen and sulfur-containing heterocyclic ring. .)

  Specific examples of the compounds represented by the above general formulas (2), (3) and (4) include the following. For example, N, N-dihydroxyethyl-methylamine, N, N-dihydroxyethyl-ethylamine, N, N-dihydroxyethyl-isopropylamine, N, N-dihydroxyethyl-n-butylamine, N, N-dihydroxyethyl-t -Butylamine, methyliminobispropylamine, N, N-dihydroxyethylaniline, N, N-dihydroxyethyl-m-toluidine, N, N-dihydroxyethyl-p-toluidine, N, N-dihydroxyethyl-m-chloroaniline N, N-dihydroxyethylbenzylamine, N, N-dimethyl-N ′, N′-dihydroxyethyl-1,3-diaminopropane, N, N-diethyl-N ′, N′-dihydroxyethyl-1,3 -Diaminopropane, N-hydroxyethyl-piperazine, N N-dihydroxyethyl-piperazine, N-hydroxyethoxyethyl-piperazine, 1,4-bisaminopropyl-piperazine, N-aminopropyl-piperazine, dipicolinic acid, 2,3-diaminopyridine, 2,5-diaminopyridine, 2 , 6-diamino-4-methylpyridine, 2,6-dihydroxypyridine, 2,6-pyridine-dimethanol, 2- (4-pyridyl) -4,6-dihydroxypyrimidine, 2,6-diaminotriazine, 2, 5-diaminotriazole, 2,5-diaminooxazole and the like can be mentioned.

  Also, ethylene oxide adducts and propylene oxide adducts of these tertiary amino compounds can be used in the present invention. Examples of the adduct include compounds represented by the following structural formula. In the following formula, m represents an integer of 1 to 60, and n represents an integer of 1 to 6.

  The hydrophilic resin used in the present invention is characterized by having a polysiloxane segment in its structure. Examples of the polysiloxane compound that can be used for introducing the polysiloxane segment into the hydrophilic resin molecule include, for example, one or more reactive groups in the molecule, such as an amino group, an epoxy group, a hydroxyl group, and a mercapto. And compounds having a group or a carboxyl group. Preferable examples of the polysiloxane compound having a reactive group as described above include the following compounds.

Amino-modified polysiloxane compounds

Epoxy-modified polysiloxane compound

Alcohol-modified polysiloxane compound

Mercapto-modified polysiloxane compounds

Carboxyl-modified polysiloxane compound

  Of the polysiloxane compounds having active hydrogen-containing groups as described above, polysiloxane polyols and polysiloxane polyamines are particularly useful. The listed compounds are all preferred compounds used in the present invention, and the present invention is not limited to these exemplified compounds. Accordingly, not only the above-exemplified compounds but also any other compounds that are currently commercially available and can be easily obtained from the market can be used in the present invention.

  As the organic polyisocyanate used for synthesizing the hydrophilic resin characterizing the present invention, any known ones in the synthesis of conventional polyurethane resins can be used and are not particularly limited. Preferable examples include 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), hydrogenated MDI, isophorone diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 2,4-trilylene. Ranges isocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, etc., or polyurethane prepolymers obtained by reacting these organic polyisocyanates with low molecular weight polyols or polyamines to form terminal isocyanates can also be used.

  The hydrophilic component used for the synthesis of the hydrophilic resin characterizing the present invention is preferably a hydrophilic compound having a hydroxyl group, an amino group, a carboxyl group and the like and having a weight average molecular weight in the range of 400 to 8,000. Examples of the polyol having a hydroxyl group at the end and hydrophilicity include polyethylene glycol, polyethylene glycol / polytetramethylene glycol copolymer polyol, polyethylene glycol / polypropylene glycol copolymer polyol, polyethylene glycol adipate polyol, polyethylene glycol succinate polyol, polyethylene Examples include glycol / polyε-lactone copolymer polyol, polyethylene glycol / polyvalerolactone copolymer polyol, and the like.

  Examples of the polyamine having a terminal amino group and hydrophilicity include polyethylene oxide diamine, polyethylene oxide propylene oxide diamine, polyethylene oxide triamine, and polyethylene oxide propylene oxide triamine. Other examples include ethylene oxide adducts having a carboxyl group or a vinyl group.

  In the present invention, in order to impart water resistance to the hydrophilic resin, it is also possible to use other polyols, polyamines, polycarboxylic acids and the like that do not have a hydrophilic chain together with the hydrophilic component.

  As the chain extender used as necessary in the synthesis of the hydrophilic resin characterizing the present invention, for example, any conventionally known chain extender such as a low-molecular diol or a diamine can be used. Not. Specific examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, ethylenediamine, hexamethylenediamine, and the like.

  The hydrophilic resin obtained by using the above raw material components, the tertiary amino group, and the polysiloxane segment in the molecular chain has a weight average molecular weight (in terms of standard polystyrene measured by GPC). It is preferable that it is a thing of the range of 3,000-800,000. A more preferred weight average molecular weight is in the range of 5,000 to 500,000.

  The tertiary amino group content in the hydrophilic resin particularly suitable for use in the method for removing radioactive iodine and radioactive cesium of the present invention is preferably in the range of 0.1 to 50 eq (equivalent) / kg. Preferably it is 0.5-20 eq / kg. If the content of the tertiary amino group is less than 0.1 eq / kg, that is, less than 1 per 10,000 molecular weight, the intended release of radioactive iodine, which is the intended purpose of the present invention, becomes insufficient. When the content of the tertiary amino group exceeds 50 eq / kg, that is, exceeds 500 per 10,000 molecular weight, the hydrophobicity due to the decrease of the hydrophilic portion in the resin becomes strong and the water absorption performance is inferior. This is not preferable.

  Further, the content of the polysiloxane segment in the hydrophilic resin particularly suitable for the method for removing radioactive iodine and radioactive cesium of the present invention is in the range of 0.1 to 12% by mass, particularly in the range of 0.5 to 10% by mass. Is preferred. If the content of the polysiloxane segment is less than 0.1% by mass, the expression of water resistance and surface blocking resistance, which are the objects of the present invention, will be insufficient. Is unfavorable because it increases the water absorption performance and impairs the adsorption of radioactive iodine.

  Further, the content of the hydrophilic segment of the hydrophilic resin particularly suitable for the method for removing radioactive iodine and radioactive cesium of the present invention is preferably in the range of 20 to 80% by mass, more preferably in the range of 30 to 70% by mass. is there. If content of a hydrophilic segment is less than 20 mass%, it will be inferior to water absorption performance and the removability of radioactive iodine will fall. On the other hand, when it exceeds 80 mass%, it will become inferior to water resistance, and is unpreferable.

  The hydrophilic resin composition of the present invention suitable for the method for removing radioactive iodine and radioactive cesium of the present invention comprises a ferrocyanide compound represented by bitumen (hereinafter referred to as bitumen) in the hydrophilic resin described above. It is obtained by dispersing. Specifically, it can be produced by adding bitumen and a dispersion solvent to the above-described hydrophilic resin and performing a dispersion operation with a predetermined disperser. As the disperser used for the dispersion, any disperser that is usually used for pigment dispersion can be used without any problem. For example, paint conditioner (manufactured by Red Devil), ball mill, pearl mill (manufactured by Eirich), sand mill, visco mill, attritor mill, basket mill, wet jet mill (manufactured by Genus), etc. It is preferable to set in view of the above. Further, as the media, glass beads, zirconia beads, alumina beads, magnetic beads, stainless beads, etc. can be used.

  As a dispersion ratio of the hydrophilic resin and the bitumen in the hydrophilic resin composition of the present invention, a blending ratio of 1 to 200 parts by weight of bitumen with respect to 100 parts by weight of the hydrophilic resin is used. If the bitumen is less than 1 part by mass, the removal of radioactive cesium is insufficient, and if it exceeds 200 parts by mass, the mechanical properties of the composition become weak and the water resistance becomes inferior, and the shape can be maintained in radioactively contaminated water. It is not preferable because it disappears.

  In the method for removing radioactive iodine and radioactive cesium of the present invention, it is preferable to use the hydrophilic resin composition of the present invention having the above-described configuration in the following form. That is, a film obtained by applying a solution of the hydrophilic resin composition to a release paper, a release film or the like so that the thickness after drying is 5 to 100 μm, preferably 10 to 50 μm, and drying in a drying furnace. The thing of the shape is mentioned. In this case, it is peeled off from the release paper or film at the time of use, and used as a removal film for radioactive iodine / radiocesium. In addition, a resin solution obtained from the raw materials described above may be applied or impregnated on various base materials. As the base material in this case, metal, glass, wood, fiber, various plastics and the like can be used.

  The hydrophilic resin composition film characterized by the present invention obtained as described above or a sheet coated on various substrates is immersed in a radioactive waste liquid or a waste liquid obtained by decontaminating radioactive solids with water in advance. By doing so, both radioactive iodine and radioactive cesium can be selectively removed. In addition, solid iodine contaminated by radioactivity can be prevented from diffusing radioactive iodine and radioactive cesium by covering with a film or sheet made of the hydrophilic resin composition of the present invention.

  Since the film or sheet made of the hydrophilic resin composition of the present invention does not dissolve in water, it can be easily taken out from the waste liquid after decontamination. In this way, decontamination can be performed easily and at low cost without requiring special equipment or electric power to remove both radioactive iodine and radioactive cesium. Furthermore, if the absorbed water is dried and heated to 100 to 170 ° C., the resin is softened, the volume shrinks, and the effect of reducing the volume of radioactive waste can be expected.

  Next, the present invention will be described in more detail with reference to specific production examples, examples, and comparative examples, but the present invention is not limited to these examples. Further, “parts” and “%” in the following examples are based on mass unless otherwise specified.

[Production Example 1] (Synthesis of hydrophilic polyurethane resin having tertiary amino group and polysiloxane segment)
A reaction vessel equipped with a stirrer, a thermometer, a gas introduction tube and a reflux condenser was replaced with nitrogen. In the vessel, 8 parts of polydimethylsiloxane polyol (molecular weight 3,200) having the following structure, polyethylene glycol (molecular weight 2, 040) 142 parts, N-methyldiethanolamine 20 parts and diethylene glycol 5 parts were dissolved in a mixed solvent of 100 parts methyl ethyl ketone and 200 parts dimethylformamide. And the solution which melt | dissolved 73 parts hydrogenation MDI in 100 parts methyl ethyl ketone was dripped gradually, stirring well at 60 degreeC. After completion of the dropwise addition, the mixture was reacted at 80 ° C. for 6 hours, and then 60 parts of methyl ethyl ketone was added to obtain a hydrophilic polyurethane resin solution having a structure defined in the present invention.

  The resin solution obtained above had a viscosity of 330 dPa · s (25 ° C.) at a solid content of 35%. Moreover, the hydrophilic resin film formed from this solution had a breaking strength of 20.5 MPa, a breaking elongation of 400%, and a thermal softening temperature of 103 ° C.

[Production Example 2] (Synthesis of hydrophilic polyurea resin having tertiary amino group and polysiloxane segment)
In the same reaction vessel as used in Production Example 1, 5 parts of polydimethylsiloxane diamine (molecular weight 3,880) having the following structure, polyethylene oxide diamine (“Jeffamine ED” (trade name), manufactured by Huntsman; molecular weight 2 , 145), 145 parts of methyliminobispropylamine and 5 parts of 1,4-diaminobutane were dissolved in 250 parts of dimethylformamide, and the internal temperature was well stirred at 20-30 ° C. Then, while stirring, a solution prepared by dissolving 75 parts of hydrogenated MDI in 100 parts of dimethylformamide was gradually added dropwise to react. After completion of the dropwise addition, the internal temperature was gradually raised, and when the temperature reached 50 ° C., the mixture was further reacted for 6 hours, and then 124 parts of dimethylformamide was added to obtain a hydrophilic polyurea resin solution having a structure defined in the present invention.

  The resin solution obtained above had a solid content of 35% and a viscosity of 315 dPa · s (25 ° C.). Moreover, the hydrophilic resin film formed from this resin solution had a breaking strength of 31.3 MPa, a breaking elongation of 370%, and a thermal softening temperature of 147 ° C.

[Production Example 3] (Synthesis of hydrophilic polyurethane-polyurea resin having tertiary amino group and polysiloxane segment)
In the same reaction vessel as that used in Production Example 1, 5 parts of ethylene oxide addition type polydimethylsiloxane (molecular weight 4,500) having the following structure, polyethylene oxide diamine ("Jeffamine ED" (trade name), manufactured by Huntsman Molecular weight 2,000) 145 parts, N, N-dimethyl-N ′, N′-dihydroxyethyl-1,3-diaminopropane 30 parts and 1,4-diaminobutane 5 parts, methyl ethyl ketone 150 parts and 150 parts Was dissolved in a mixed solvent of dimethylformamide, and the internal temperature was well stirred at 20 to 30 ° C. And the solution which melt | dissolved 72 parts hydrogenated MDI in 100 parts methyl ethyl ketone was dripped gradually, stirring. After completion of dropping, the mixture was reacted at 80 ° C. for 6 hours. After completion of the reaction, 75 parts of methyl ethyl ketone was added to obtain a hydrophilic polyurethane-polyurea resin solution having a structure defined in the present invention.

  The resin solution obtained above had a solid content of 35% and a viscosity of 390 dPa · s (25 ° C.). The hydrophilic resin film formed from this resin solution had a breaking strength of 22.7 MPa, a breaking elongation of 450%, and a thermal softening temperature of 127 ° C.

[Production Example 4] (Synthesis of non-hydrophilic polyurethane resin containing neither tertiary amino group nor polysiloxane segment used in Comparative Example 1)
A reaction vessel similar to that used in Production Example 1 was purged with nitrogen, and 150 parts of polybutylene adipate having an average molecular weight of about 2,000 and 15 parts of 1,4-butanediol were dissolved in 250 parts of dimethylformamide. Stir well at 60 ° C. While stirring, 62 parts of hydrogenated MDI dissolved in 171 parts of dimethylformamide were gradually added dropwise. After completion of the dropping, the resin solution used in the comparative example was obtained by reacting at 80 ° C. for 6 hours. This resin solution had a viscosity of 3.2 MPa · s (25 ° C.) at a solid content of 35%. The resin film obtained from this resin solution had a breaking strength of 45 MPa, a breaking elongation of 480%, and a thermal softening temperature of 110 ° C.

[Production Example 5] (Synthesis of non-hydrophilic polyurethane resin containing a tertiary amino group and containing no polysiloxane segment used in Comparative Example 2)
The same reaction vessel as used in Production Example 1 was purged with nitrogen, 150 parts of polybutylene adipate having an average molecular weight of about 2,000, 20 parts of N-methyldiethanolamine, 5 parts of diethylene glycol, 200 parts of methyl ethyl ketone and 150 parts of It melt | dissolved in the mixed solvent with dimethylformamide, and stirred well at 60 degreeC. While stirring, a solution of 74 parts of hydrogenated MDI dissolved in 112 parts of methyl ethyl ketone was gradually added dropwise. After completion of the dropping, the resin solution used in the comparative example was obtained by reacting at 80 ° C. for 6 hours. This resin solution had a viscosity of 510 dPa · s (25 ° C.) at a solid content of 35%. The resin film formed from this solution had a breaking strength of 23.5 MPa, a breaking elongation of 470%, and a thermal softening temperature of 110 ° C.

  The weight average molecular weight, tertiary amino group, and polysiloxane segment content of each resin of Production Examples 1 to 5 obtained above were as shown in Table 1 below.

<Examples 1-3, Comparative Examples 1 and 2>
Each resin solution of Production Examples 1 to 5 and bitumen [Miroli Blue (color name); manufactured by Dainichi Seika Kogyo Co., Ltd.] are used in each formulation shown in Table 2, and high-density alumina balls (3.5 g / mL) For 24 hours with a ball mill. And the content after dispersion | distribution was taken out through the sieve of 100 mesh made from a polyester resin, and each liquid resin composition containing a resin solution and a bitumen was obtained.

[Evaluation]
Using each of the resin solutions of Examples 1 to 3 and Comparative Examples 1 and 2 obtained above, it was coated on a release paper, dried by heating at 110 ° C. for 3 minutes to evaporate the solvent, and had a thickness of about 20 μm. Each resin film was formed. Using the resin films of Examples 1 to 3 and Comparative Examples 1 and 2 thus obtained, the following items were tested and evaluated.

<Blocking resistance (sticking resistance)>
Each resin film of the example and the comparative example was superposed on each other and then subjected to a load of 0.29 MPa and left at 40 ° C. for 1 day. Thereafter, the blocking property between the superimposed films was visually observed and evaluated according to the following criteria. The results are shown in Table 3.
○: No blocking property △: Slight blocking property ×: Blocking property

<Water resistance>
Each resin film of Examples and Comparative Examples was cut into a shape of 20 μm in thickness, 5 cm in length × 1 cm in width, immersed in water at 25 ° C. for 12 hours, and measured for the vertical length of the film after the immersion test. The expansion coefficient (%) in the longitudinal direction of the film was measured and calculated using the following formula. And the film whose expansion coefficient was 200% or less was evaluated as (circle), and the film which exceeded 200% was set to x, and water resistance was evaluated. The results are shown in Table 3.
Expansion coefficient (%) = (vertical length after test / vertical length before test) × 100

<Effect on iodine ion and cesium ion removal>
Using the transparent resin films of Examples and Comparative Examples, the effects on the removal of iodine ions and cesium ions were evaluated by the following methods.
(Production of iodine solution and cesium solution for evaluation test)
The iodine solution for the evaluation test was prepared by dissolving potassium iodide in ion-exchanged pure water so that the iodine ion concentration was 200 mg / L (200 ppm). Moreover, the cesium solution for an evaluation test was prepared by dissolving cesium chloride in ion-exchanged pure water so that the cesium ion concentration was 200 mg / L (200 ppm). If iodine ions and cesium ions can be removed, naturally, radioactive iodine and radioactive cesium can be removed.

(Evaluation results for the resin composition of Example 1)
20 g of the resin film produced using the hydrophilic resin composition of Example 1 was immersed in a mixed solution of 50 ml of iodine solution and 50 ml of cesium solution prepared for the evaluation test previously (25 ° C.), and every elapsed time. The iodine ion concentration and the cesium ion concentration in the solution were measured with an ion chromatograph (manufactured by Tosoh; IC2001). The results are shown in Table 4. As shown in Table 4, it was confirmed that both the iodine ion concentration and the cesium ion concentration in the solution decreased for each elapsed time. In Table 4, the removal rates of these ions in the solution for each elapsed time are also shown. The results are shown in FIG. 1 and FIG.

(Evaluation results for the resin composition of Example 2)
Elapsed time in the same manner as using the resin film prepared using the hydrophilic resin composition of Example 1, except that 20 g of the resin film prepared using the hydrophilic resin composition of Example 2 was used. Each time, the iodine ion concentration and the cesium ion concentration in the solution were measured. The obtained results are shown in Table 5 and FIGS. 1 and 2 as in the case of Example 1 described above. As a result, even when the hydrophilic resin composition of Example 2 was used, it was confirmed that both the iodine ion concentration and the cesium ion concentration in the solution decreased every elapsed time.

(Evaluation results for the resin composition of Example 3)
Elapsed time in the same manner as using the resin film prepared using the hydrophilic resin composition of Example 1 except that 20 g of the resin film prepared using the hydrophilic resin composition of Example 3 was used. Each time, the iodine ion concentration and the cesium ion concentration in the solution were measured. The obtained results are shown in Table 6 and FIGS. 1 and 2 as in the case of Example 1 described above. As a result, even when the hydrophilic resin composition of Example 3 was used, it was confirmed that both the iodine ion concentration and the cesium ion concentration in the solution decreased every elapsed time.

(Evaluation results for the resin composition of Comparative Example 1)
In the same manner as that using the resin film prepared using the hydrophilic resin composition of Example 1, except that 20 g of the resin film prepared using the non-hydrophilic resin composition of Comparative Example 1 was used. The iodine ion concentration and the cesium ion concentration in the solution were measured every hour. The obtained results are shown in Table 7 and FIGS. 3 and 4 as in the case of Example 1 described above. As a result, when the hydrophilic resin composition of Comparative Example 1 was used, neither iodine ion concentration nor cesium ion concentration could be removed, and the superiority of the hydrophilic resin compositions of Examples 1 to 3 was confirmed. It was done.

(Evaluation results for the resin composition of Comparative Example 2)
Elapsed time in the same manner as using the film prepared using the hydrophilic resin composition of Example 1 except that 20 g of the resin film prepared using the non-hydrophilic resin composition of Comparative Example 2 was used. Each time, the iodine ion concentration and the cesium ion concentration in the solution were measured. The obtained results are shown in Table 8 and FIGS. 3 and 4 as in the case of Example 1 described above. As a result, when the hydrophilic resin composition of Comparative Example 2 was used, although the removal rate of iodine ions and cesium ions was improved as compared with the case of using the hydrophilic resin composition of Comparative Example 2, Examples 1 to Compared with the case where the hydrophilic resin composition of No. 3 was used, the superiority of the hydrophilic resin compositions of Examples was confirmed.

  According to the present invention, radioactive iodine and radioactive cesium in radioactive liquid waste and radioactive solids can be easily removed at a low cost and with a new removal method that does not require an energy source such as electric power. become. In the present invention, a hydrophilic resin composition containing a hydrophilic resin into which a polysiloxane segment is further introduced in addition to a hydrophilic segment and a tertiary amino group ionically bonded to radioactive iodine is used in the structure. In addition, the water resistance and the blocking resistance (sticking resistance) of the resin surface brought about by the presence of the polysiloxane segment are realized, and the practicality of the removal treatment using a film or the like is enhanced. By using a hydrophilic resin composition containing a ferrocyanide compound represented by bitumen, radioactive cesium can be removed at the same time, and the removed radioactive iodine and radioactive cesium can be taken in and more stably immobilized. A hydrophilic resin composition having high practical value is provided. Furthermore, since the main component of the resin composition provided by the present invention is a resin composition, it is possible to reduce the volume of radioactive waste as necessary. The problem of radioactive waste can be reduced and its use is expected.

Claims (8)

Radioactive iodine / radioactive cesium removed by using a hydrophilic resin composition comprising a hydrophilic resin and a metal ferrocyanide together with radioactive iodine and radioactive cesium present in radioactive liquid waste and / or radioactive solids A method for removing
The hydrophilic resin has a hydrophilic segment and a hydrophilic group in the molecule, but is insoluble in water and warm water, and has a main chain and / or side in the structure. Including at least one selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin having a tertiary amino group and a polysiloxane segment in the chain; and
Radioiodine / radioactive cesium characterized in that the hydrophilic resin composition comprises at least a metal ferrocyanide compound dispersed in an amount of 1 to 200 parts by mass with respect to 100 parts by mass of the hydrophilic resin. Removal method.   The method for removing radioactive iodine / radioactive cesium according to claim 1, wherein the hydrophilic segment is a polyethylene oxide segment.   The hydrophilic resin contains a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group, at least one active hydrogen-containing group and a polysiloxane segment in the same molecule. The method for removing radioactive iodine and radioactive cesium according to claim 1, wherein the compound is a resin formed by using a compound contained in the raw material as a part of a raw material. The method for removing radioactive iodine and radioactive cesium according to any one of claims 1 to 3, wherein the metal ferrocyanide compound is a compound represented by the following general formula (1).
_{A x M y [Fe (CN} ) 6] (1)
[Wherein, A is any one selected from K, Na, and NH ₄ , M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, and x, y Satisfies the formula x + ny = 4 (x is a number from 0 to 3), and n represents the valence of M. ] A hydrophilic resin composition showing a function capable of fixing both radioactive iodine and radioactive cesium in a liquid and / or solid matter,
A hydrophilic resin and a ferrocyanide metal compound,
The hydrophilic resin contains a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group, at least one active hydrogen-containing group and a polysiloxane segment in the same molecule. A hydrophilic segment formed as part of the raw material, a tertiary amino group and a polysiloxane segment in the molecular chain, and having a hydrophilic group in the molecule Is a resin that is insoluble in water and warm water, and
A hydrophilic resin composition for removing radioactive iodine and radioactive cesium, wherein at least a metal ferrocyanide compound is dispersed in an amount of 1 to 200 parts by mass with respect to 100 parts by mass of the hydrophilic resin. . A hydrophilic resin composition showing a function capable of fixing both radioactive iodine and radioactive cesium in a liquid and / or solid matter,
A hydrophilic resin and a ferrocyanide metal compound,
The hydrophilic resin is an organic polyisocyanate, a high molecular weight hydrophilic polyol and / or polyamine which is a hydrophilic component, at least one active hydrogen-containing group and at least one tertiary amino group in the same molecule. And a hydrophilic segment obtained by reacting a compound having in the compound with a compound having at least one active hydrogen-containing group and a polysiloxane segment in the same molecule, and having a hydrophilic group in the molecule. A hydrophilic polyurethane resin having hydrophilic properties that is insoluble in water and hot water, and has a tertiary amino group and a polysiloxane segment in the main chain and / or side chain in the structure, And at least one selected from the group consisting of a hydrophilic polyurea resin and a hydrophilic polyurethane-polyurea resin, and
A hydrophilic resin composition for removing radioactive iodine and radioactive cesium, wherein at least a metal ferrocyanide compound is dispersed in an amount of 1 to 200 parts by mass with respect to 100 parts by mass of the hydrophilic resin. .   The hydrophilic resin composition for removing radioactive iodine and radioactive cesium according to claim 5 or 6, wherein the hydrophilic segment of the hydrophilic resin is a polyethylene oxide segment. The hydrophilic resin composition for removing radioactive iodine / radiocesium according to any one of claims 5 to 7, wherein the metal ferrocyanide compound is a compound represented by the following general formula (1).
_{A x M y [Fe (CN} ) 6] (1)
[Wherein, A is any one selected from K, Na, and NH ₄ , M is any one selected from Ca, Mn, Fe, Co, Ni, Cu, and Zn, and x, y Satisfies the formula x + ny = 4 (x is a number from 0 to 3), and n represents the valence of M. ]

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