JP5725621B2 - 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 removal method capable of removing both radioactive iodine and radioactive cesium present in radioactive liquid waste and / or radioactive solids generated from nuclear power plants and spent nuclear fuel facilities, and fixing both of the radioactive iodine and radioactive cesium. The present invention relates to a hydrophilic resin composition exhibiting a function of converting to a hydrophilic resin composition.

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 long-lived iodine 129 (half-life: 1.57 years × 10 ⁷ ) and short half-life iodine 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, if radioactive iodine is taken in through breathing, water, or food, it is collected in the thyroid gland just like normal iodine and increases internal radiation exposure. Don't 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. This radioactive cesium is mainly composed of 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. In addition, radioactive cesium is easily absorbed by the human body through breathing and skin, and is almost uniformly distributed throughout the body.

  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 Extensive radioactive contamination is 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.

  For such a situation, as a treatment method of the generated radioactive iodine, a washing treatment method, a physical / chemical treatment method by filling a solid adsorbent using fibrous activated carbon or the like (see Patent Documents 1 and 2), ions Treatment with an exchange agent (see Patent Document 3) and the like have been studied.

  However, any of the above-described methods has problems, 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 are put to practical use in the cleaning treatment method, but in order to store this as a liquid for a long period of time by processing with a cleaning method using a liquid adsorbent, quantitatively, There are also many safety issues. In addition, in the physical and chemical treatment system with solid adsorbent filling, the supplemented 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 method 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 is not exhibited at higher temperatures.

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

  However, all of the above-described processing methods require large facilities such as a circulation pump, a purification tank, and a filling tank containing each adsorbent, and a great amount of energy for operating 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, radioactive cesium, etc. diffused to the surrounding area due to the runaway accident of the reactor falls into a very difficult situation, which may expand the radioactive contamination There is concern about the situation. 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

  Therefore, the main object of the present invention is to provide a simple and effective removal technique that can remove radioactive iodine and radioactive cesium together, but in that case, the problem of the prior art is solved and simplified. In addition, at low cost and without the need for an energy source such as electric power, the removed radioactive iodine and radioactive cesium can be taken into the solid body and stably fixed. The object is to provide a new technology for simultaneous removal of radioactive iodine and radioactive cesium that can be reduced in volume. An object of the present invention is to provide a novel hydrophilic resin composition that has a function capable of immobilizing both radioactive iodine and radioactive cesium described above, and that can be removed together. There is.

The above object is achieved by the present invention described below. That is, the present invention is a method for removing radioactive iodine and radioactive cesium in a radioactive liquid waste and / or radioactive solid using a hydrophilic resin composition comprising a hydrophilic resin composition and zeolite. A method for removing radioactive cesium, wherein the hydrophilic resin composition has a hydrophilic segment and has a hydrophilic group in the molecule, but is a resin insoluble in water and warm water, At least one hydrophilic resin selected from the group consisting of hydrophilic polyurethane resins, hydrophilic polyurea resins, and hydrophilic polyurethane-polyurea resins having a tertiary amino group in the main chain and / or side chain in the structure. And at least zeolite is dispersed at a ratio of 1 to 200 parts by mass with respect to 100 parts by mass of the hydrophilic resin. It provides a method for removing sexual cesium.

［但し、式（１）中、Ｍ²⁺は、Ｃａ²⁺、Ｍｎ²⁺、Ｂａ²⁺又はＭｇ²⁺のいずれかであり、Ｍ⁺は、Ｎａ⁺、Ｋ⁺又はＬｉ⁺のいずれかであり、ｍは１〜１８のいずれかの数、ｎは１〜７０のいずれかの数である。］ The following are mentioned as a preferable form of this invention. The hydrophilic segment is a polyethylene oxide segment. The hydrophilic resin is a resin formed by using a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group as a raw material. The zeolite is a compound represented by the following general formula (1).

[In the formula (1), M ²⁺ is, Ca ^2+, Mn ^2+, is either Ba ²⁺ or Mg ^2+, M ⁺ is, Na ^+, K ⁺ or Li ⁺ either M is any number from 1 to 18, and n is any number from 1 to 70. ]

  In the present invention, as another embodiment, there is provided a hydrophilic resin composition having a function capable of fixing either radioactive iodine or radioactive cesium in a liquid and / or a solid material, comprising a hydrophilic resin and zeolite. A hydrophilic segment formed by using a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group as a part of a raw material, A resin having a tertiary amino group, insoluble in water and warm water, and at least 1 to 200 parts by mass of zeolite dispersed with respect to 100 parts by mass of the hydrophilic resin A hydrophilic resin composition for removing radioactive iodine and radioactive cesium is provided.

Furthermore, in the present invention, as another embodiment, there is provided a hydrophilic resin composition having a function capable of fixing either radioactive iodine or radioactive cesium in a liquid and / or solid matter, wherein the hydrophilic resin and zeolite are combined. The hydrophilic resin comprises 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. It is a resin obtained by reacting a compound in the same molecule, having a hydrophilic segment, having a hydrophilic group in the molecule, but insoluble in water and warm water, and has a structure. At least 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 in the main chain and / or side chain therein A hydrophilic resin for removing radioactive iodine and radioactive cesium, which is a seed and has at least 1 to 200 parts by mass of zeolite dispersed with respect to 100 parts by mass of the hydrophilic resin A composition is provided.

［但し、式（１）中、Ｍ²⁺は、Ｃａ²⁺、Ｍｎ²⁺、Ｂａ²⁺又はＭｇ²⁺のいずれかであり、Ｍ⁺は、Ｎａ⁺、Ｋ⁺又はＬｉ⁺のいずれかであり、ｍは１〜１８のいずれかの数、ｎは１〜７０のいずれかの数である。］ As a preferable form of any of the above-described hydrophilic resin compositions of the present invention, the hydrophilic segment is a polyethylene oxide segment; the zeolite is a compound represented by the following general formula (1), Is mentioned.

[In the formula (1), M ²⁺ is, Ca ^2+, Mn ^2+, is either Ba ²⁺ or Mg ^2+, M ⁺ is, Na ^+, K ⁺ or Li ⁺ either M is any number from 1 to 18, and n is any number from 1 to 70. ]

  According to the present invention, it is possible to provide an effective and simple removal technique that can remove radioactive iodine and radioactive cesium present in a liquid or solid matter together. More specifically, according to the present invention, radioactive iodine and radioactive cesium are simply and at low cost, and do not require an energy source such as electric power, and the removed radioactive iodine and radioactive cesium are contained inside the solid. Thus, a novel technique capable of removing radioactive iodine and radioactive cesium together, which can be stably fixed and can reduce the volume of radioactive waste as required, is provided. In addition, according to the present invention, in particular, it has a function capable of immobilizing both radioactive iodine and radioactive cesium, and it can be realized to remove these together, and the main component thereof is a resin composition. Therefore, a novel hydrophilic resin composition capable of reducing the volume of radioactive waste as required is provided. These significant effects of the present invention include organic polyisocyanates, high molecular weight hydrophilic polyols and / or polyamines (hereinafter referred to as “hydrophilic components”), at least one active hydrogen-containing group and at least one third. At least one hydrophilic resin selected from the group consisting of a hydrophilic polyurethane resin obtained by reacting a compound having a secondary amino group in the same molecule, a hydrophilic polyurea resin, and a hydrophilic polyurethane-polyurea resin; This is achieved by a very simple method of utilizing a hydrophilic resin composition obtained by dispersing the slag.

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 water solubility, 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 the comparative examples 1 and 2. FIG. 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 the comparative examples 1 and 2. FIG.

Next, the present invention will be described in more detail with reference to preferred embodiments.
The hydrophilic resin composition of the present invention, which characterizes the removal method of the present invention, comprises a composition in which a zeolite is dispersed in a hydrophilic resin, and the hydrophilic resin comprises a hydrophilic segment having a hydrophilic component as a structural unit, and And having a tertiary amino group-containing segment whose constituent unit is a component having at least one tertiary amino group. 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. Any material having an amino group-containing segment may be used. 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. It is distinguished from water-soluble resins such as acids and cellulose derivatives. Details thereof will be described later.

  The hydrophilic resin composition of the present invention comprises a hydrophilic resin and zeolite, and the reason why it is possible to remove radioactive iodine and radioactive cesium together by using the composition. The present inventors consider as follows. First, the hydrophilic resin used in the present invention exhibits excellent water absorption by the hydrophilic segment, and further, by introducing a tertiary amino group into 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, is fixed in the hydrophilic resin.

  However, since the ionic bond as described above is 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. It was expected that it would be difficult to fix and remove the fixing state. However, according to the study by the present inventors, it was actually found that the 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, in the specific hydrophilic resin used in the present invention, a hydrophobic portion is also present in the molecule, and after an ionic bond is formed between the tertiary amino group in the resin and radioactive iodine. It is speculated that this hydrophobic part may surround the hydrophilic part (hydrophilic segment) and the ion binding part. For these reasons, in the present invention, by using the hydrophilic resin composition of the present invention including a hydrophilic resin having a specific structure, radioactive iodine is fixed to the resin and can be removed. Conceivable.

  Furthermore, in the present invention, by using the hydrophilic resin composition of the present invention containing zeolite, in addition to the above-described removal of radioactive iodine, it is also possible to remove radioactive cesium, and simultaneously remove radioactive iodine and radioactive cesium. Achieve to process. Hereinafter, the zeolite used in the present invention will be described. Zeolite can be synthesized artificially, but it is a naturally occurring crystalline compound consisting of silicon, aluminum, and oxygen and having fine pores at the molecular level, and has various crystal structures. Are known. Zeolite has a unique crystal structure with pores with a very large surface area, so it exhibits a high adsorption capacity for gases and ions, a catalytic ability to assist various chemical reactions, and the size of the pores. It is also used in a wide range of fields because it is possible to screen molecules by.

［但し、式（１）中、Ｍ²⁺は、Ｃａ²⁺、Ｍｎ²⁺、Ｂａ²⁺又はＭｇ²⁺のいずれかであり、Ｍ⁺は、Ｎａ⁺、Ｋ⁺又はＬｉ⁺のいずれかであり、ｍは１〜１８のいずれかの数、ｎは１〜７０のいずれかの数である。］ Natural zeolite is a mineral having a void (pore) as described above in the crystal structure among aluminosilicates represented by the following general formula (1), but can be used in the present invention.

[In the formula (1), M ²⁺ is, Ca ^2+, Mn ^2+, is either Ba ²⁺ or Mg ^2+, M ⁺ is, Na ^+, K ⁺ or Li ⁺ either M is any number from 1 to 18, and n is any number from 1 to 70. ]

Zeolite is widely used as a catalyst and adsorbing material as described above, but in addition to these, the positive ions contained in the zeolite can be easily exchanged for other ions, thus exhibiting high ion exchange properties. Since it can be used even under conditions such as high temperatures unsuitable for resins, it is also useful as an ion exchange material. In the present invention, in addition to the above-described high adsorption function of zeolite, in particular, by utilizing the ion exchange property of zeolite, radioactive cesium present in the liquid and / or solid matter is removed. Here, the ion exchange property of zeolite will be specifically described. The ion exchange property of zeolite is expressed due to the crystal structure forming the framework of the zeolite, as described below. Since silicon (Si), which is one of the components that form the framework (crystal lattice) of zeolite, is tetravalent, oxygen, which is a divalent negative ion, can be balanced in charge with a composition of SiO _2. Since aluminum (Al), which is one component, is trivalent, when Al enters the skeleton instead of Si, one positive charge is deficient and a cation deficiency is generated. Therefore, the zeolite contains another cation, and the cation such as sodium (Na), calcium (Ca), potassium (K), etc. is taken into the generated defect portion to balance the charge. Yes. Since the cation contained in the taken-in zeolite has the property of being interchanged with other cations in the aqueous solution, the zeolite exhibits high ion exchange properties. Here, the priority order of cation exchange possessed by zeolite is as follows.

<Ion exchange order>
Cesium (Cs)> Rubidium (Rb)> NH ₄ > Barium (Ba)> Strontium (Sr)>Na>Ca> Iron (Fe)>Al> Magnesium (Mg)> Lithium (Li)

  As described above, since the ion exchange order of cesium and strontium is high, it is said that the ion exchange property of zeolite can be used for the removal of radioactive substances such as radioactive cesium, and this point is publicly known. In the present invention, the hydrophilic resin composition of the present invention in which the above-described hydrophilic resin having a unique structure capable of removing radioactive iodine is dispersed with the above-described zeolite capable of removing radioactive substances such as radioactive cesium. By using an object, a technique capable of removing radioactive iodine and radioactive cesium together is provided.

  The hydrophilic resin having a unique structure capable of removing radioactive iodine, which characterizes the present invention, includes an organic polyisocyanate, a high molecular weight hydrophilic polyol and / or polyamine, which are hydrophilic components, and at least one activity. It is obtained by reacting a compound containing a hydrogen-containing group and at least one tertiary amino group in the same molecule. That is, the compound used for introducing the hydrophilic segment and the tertiary amino group into the structure of the hydrophilic resin used in the present invention has at least one active hydrogen-containing group (reactive group) in the molecule. And having a tertiary amino group in the molecular chain. Examples of the compound having at least one active hydrogen-containing group include compounds having a reactive group such as an amino group, an epoxy group, a hydroxyl group, a mercapto group, an acid halide group, a carboxyester group, and an acid anhydride group. .

［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、−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。また、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 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).

[R ₁ in Formula (2) 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 is, -O -, - CO -, - COO -, - NHCO -, - S -, - SO -, - SO 2 - is a substituted lower alkylene group which may be coupled with such, X and Y, - OH, —COOH, —NH ₂ , —NHR ₁ (R ₁ has the same definition as above), —SH and the like, 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 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２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−（該式中の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), provided that two R ₁ form a cyclic structure. May be. R ₄ is — (CH ₂ ) _n — (wherein n is an integer of 0 to 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 heterocycle, nitrogen and oxygen-containing heterocycle, or nitrogen and sulfur-containing heterocycle. ]

  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. Note that m in any one of the following formulas represents an integer of 1 to 60, and n represents an integer of 1 to 6.

  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 (MDI), hydrogenated MDI, isophorone diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 2,4-tolylene diisocyanate, m It is also possible to use -phenylene diisocyanate, p-phenylene diisocyanate, or the like, or a polyurethane prepolymer obtained by reacting these organic polyisocyanates with low molecular weight polyols or polyamines to form terminal isocyanates.

  In addition to the organic polyisocyanate described above, the hydrophilic component used for the synthesis of the hydrophilic resin characterizing the present invention includes a weight average molecular weight having a hydroxyl group, an amino group, a carboxyl group, etc. (standard polystyrene conversion value measured by GPC. The same) is a compound having hydrophilicity 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 diamine can be used, and is not particularly limited. . For example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, ethylenediamine, hexamethylenediamine and the like can be mentioned.

  The hydrophilic segment obtained using the above raw material components and the hydrophilic resin having a tertiary amino group in the molecular chain preferably have a weight average molecular weight in the range of 3,000 to 800,000. . A more preferred weight average molecular weight is in the range of 5,000 to 500,000.

  The tertiary amino group content (equivalent) in the hydrophilic resin particularly preferably used in the present invention is preferably in the range of 0.1 to 50 eq / kg, more preferably 0.5 to 20 eq / kg. is there. 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. If the content of the tertiary amino group exceeds 50 eq / kg, that is, more than 500 per 10,000 molecular weight, the hydrophobicity increases due to the decrease of the hydrophilic portion in the resin, and the water absorption performance becomes inferior.

  Moreover, as content of the hydrophilic segment of the hydrophilic resin used especially suitably for this invention, the range of 30-80 mass% is preferable, and also the range of 50-75 mass% is preferable. If the content of the hydrophilic segment is less than 30% by mass, the water absorption performance is inferior and the radioiodine removability is lowered. On the other hand, if it exceeds 80% by mass, the water resistance becomes inferior.

  The hydrophilic resin composition of the present invention used in the method for removing radioactive iodine / radiocesium of the present invention can be obtained by dispersing the above-mentioned zeolite in the above-described hydrophilic resin. Specifically, it can be produced by adding zeolite 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 select and set in view of the property and economy. Further, as the media, glass beads, zirconia beads, alumina beads, magnetic beads, stainless beads, etc. can be used.

  As the dispersion ratio of the hydrophilic resin and the zeolite in the hydrophilic resin composition of the present invention, it is preferable to use a mixture of zeolite at a ratio of 1 to 200 parts by mass with respect to 100 parts by mass of the hydrophilic resin. If the amount of zeolite is less than 1 part by mass, the effect of removing radioactive cesium may be insufficient. If the amount exceeds 200 parts by mass, the mechanical properties of the composition will be weak and the water resistance will be inferior. This is not preferable because the shape cannot be maintained. In addition, when determining the composition ratio of the hydrophilic resin and the zeolite in the hydrophilic resin composition of the present invention, the ion-exchanged ions are eluted from the zeolite into the aqueous solution according to the above-described ion exchange order of the zeolite. This point needs to be taken into consideration to prevent the occurrence of secondary contamination.

  In carrying out the method for removing radioactive iodine / radiocesium 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, the hydrophilic resin composition solution was applied to a release paper or a release film so that the thickness after drying was 5 to 100 μm, preferably 10 to 50 μm, and dried in a drying furnace. What was made into a film form is mentioned. In this case, it peels from a release paper, a release film, etc. at the time of use, and uses it as a removal film of a radioactive iodine and radioactive cesium. 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 sheet made of the hydrophilic resin composition of the present invention obtained as described above and immersed on a film or various substrates is immersed in a radioactive waste liquid or a waste liquid in which radioactive solids have been decontaminated with water in advance. Thus, both radioactive iodine and radioactive cesium existing in these liquids can be selectively removed. In addition, for solid matter contaminated with radioactivity, diffusion of radioactive iodine and radioactive cesium can be prevented by covering the solid matter 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. Thus, no special equipment or electric power is required to remove both radioactive iodine and radioactive cesium, and decontamination can be performed easily and at low cost. 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 thereto. Further, “parts” and “%” in the following examples are based on mass unless otherwise specified.

[Production Example 1] (Synthesis of tertiary amino group-containing hydrophilic polyurethane resin)
A reaction vessel equipped with a stirrer, thermometer, gas introduction tube and reflux condenser was replaced with nitrogen, 150 parts of polyethylene glycol (molecular weight 2,040), 20 parts of N-methyldiethanolamine, 5 parts of diethylene glycol, 200 parts of methyl ethyl ketone ( Hereinafter, it was dissolved in a mixed solvent of 150 parts of dimethylformamide (hereinafter abbreviated as DMF) and stirred at 60 ° C. well. And the solution which melt | dissolved 74 parts hydrogenation MDI in 112 parts MEK was dripped gradually, stirring. After completion of the dropwise addition, the mixture was reacted at 80 ° C. for 6 hours to obtain a hydrophilic resin solution defined in the present invention. This resin solution had a solid content of 35% and a viscosity of 530 dPa · s (25 ° C.). Moreover, the hydrophilic resin film formed from this solution had a breaking strength of 24.5 MPa, a breaking elongation of 450%, and a thermal softening temperature of 115 ° C.

[Production Example 2] (Tertiary amino group-containing hydrophilic polyurea resin synthesis)
In the same reactor as used in Production Example 1, 150 parts of polyethylene oxide diamine (“Jeffamine ED” (trade name); molecular weight 2,000, manufactured by Huntsman), 30 parts of methyliminobispropylamine and 1,4 -4 parts of diaminobutane was dissolved in 200 parts of DMF, and the internal temperature was well stirred at 20-30 ° C. Then, with stirring, a solution obtained by dissolving 83 parts of hydrogenated MDI in 100 parts of DMF was gradually added dropwise to react. After completion of the dropping, the internal temperature was gradually raised, and when the temperature reached 50 ° C., the mixture was further reacted for 6 hours, and 195 parts of DMF was added to obtain a hydrophilic resin solution defined in the present invention. This resin solution had a solid content of 35% and a viscosity of 230 dPa · s (25 ° C.). Moreover, the hydrophilic resin film formed from this resin solution had a breaking strength of 27.6 MPa, a breaking elongation of 310%, and a thermal softening temperature of 145 ° C.

[Production Example 3] (Synthesis of tertiary amino group-containing hydrophilic polyurethane-polyurea resin)
In the same reaction vessel as used in Production Example 1, 150 parts of polyethylene oxide diamine (“Jeffamine ED” (trade name); molecular weight 2,000, manufactured by Huntsman), N, N-dimethyl-N ′, N ′ -30 parts of dihydroxyethyl-1,3-diaminopropane and 6 parts of triethylene glycol were dissolved in 140 parts of DMF. And the solution which melt | dissolved 70 parts hydrogenation MDI in 200 parts MEK was dripped gradually, stirring well with internal temperature 20-30 degreeC. After completion of the dropwise addition, the mixture was reacted at 80 ° C. for 6 hours, and 135 parts of MEK was added to obtain a hydrophilic resin solution defined in the present invention. This resin solution had a solid content of 35% and a viscosity of 280 dPa · s (25 ° C.). Further, the hydrophilic resin film formed from this resin solution had a breaking strength of 14.7 MPa, a breaking elongation of 450%, and a thermal softening temperature of 107 ° C.

[Production Example 4] (Synthesis of tertiary amino group-free non-hydrophilic polyurethane resin used in Comparative Example)
The same reaction vessel as 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 DMF. And what melt | dissolved 62 parts hydrogenation MDI in 171 parts DMF was dripped gradually, stirring well at 60 degreeC. After completion of the dropwise addition, the mixture was reacted at 80 ° C. for 6 hours to obtain a resin solution used in the comparative example. This resin solution had a solid content of 35% and a viscosity of 3.2 MPa · s (25 ° C.). Further, the non-hydrophilic resin film obtained from this solution had a breaking strength of 45 MPa, a breaking elongation of 480%, and a thermal softening temperature of 110 ° C.

[Production Example 5] (Tertiary amino group-containing non-hydrophilic polyurethane resin used in Comparative Example)
A reaction vessel similar to that used in Production Example 1 was replaced 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 MEK and 150 parts of Dissolved in a mixed solvent with DMF. And the solution which melt | dissolved 74 parts hydrogenation MDI in 112 parts MEK was dripped gradually, stirring well at 60 degreeC. After completion of the dropwise addition, the mixture was reacted at 80 ° C. for 6 hours to obtain a resin solution used in the comparative example. This resin solution had a solid content of 35% and a viscosity of 510 dPa · s (25 ° C.). The non-hydrophilic 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 characteristics of the resins obtained in Production Examples 1 to 5 are shown in Table 1. Specifically, the hydrophilicity evaluation, the weight average molecular weight, and the tertiary amino group equivalent (eq / kg) per 1,000 weight average molecular weights were as shown in Table 1 below.

<Examples 1-3, Comparative Examples 1-2>
Each resin solution of Production Examples 1 to 5 and zeolite (manufactured by Sun Zeolite Industry Co., Ltd.) are mixed with each formulation shown in Table 2 (expressed on a mass basis), and high-density alumina balls (3.5 g / ml) ) For 24 hours by ball mill dispersion. Then, the content after dispersion was taken out through a 100-mesh sieve made of polyester resin to obtain a liquid resin composition containing a resin solution and zeolite.

[Evaluation]
(Production of resin film)
Using the liquid core resin compositions of Examples 1 to 3 and Comparative Examples 1 and 2 described above, each resin film was prepared as follows. Specifically, after each of the above resin compositions was applied onto a release paper, the solvent was evaporated by heating and drying at 110 ° C. for 3 minutes to prepare each resin film having a thickness of about 20 μm. Next, each resin film thus obtained was used to evaluate the effect on the removal of iodine ions and cesium ions by the following method.

(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 evaluation tests was prepared by dissolving cesium chloride in pure water subjected to ion exchange treatment 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.

<The evaluation result about the resin composition of Example 1>
20 g of a resin film prepared 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 by an ion chromatograph (manufactured by Tosoh; IC2001). The measurement results are shown in Table 3. As shown in Table 3, it was confirmed that both the iodine ion concentration and the cesium ion concentration in the solution decreased with each elapsed time. In Table 3, the removal rates of these ions in the solution for each elapsed time are also shown. Further, the obtained results of the change over time are graphed and shown in FIG. 1 and FIG.

<The evaluation result about the resin composition of Example 2>
Except for using 20 g of the resin film prepared with the hydrophilic resin composition of Example 2, in the same manner as using the resin film prepared with the hydrophilic resin composition of Example 1, every elapsed time. The iodine ion concentration and the cesium ion concentration in the solution were measured. The obtained results are shown in Table 4 and FIGS. 1 and 2 as in the case of Example 1 described above.

<The evaluation result about the resin composition of Example 3>
Except for using 20 g of the resin film prepared with the hydrophilic resin composition of Example 3, in the same manner as using the resin film prepared with the hydrophilic resin composition of Example 1, every elapsed 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.

<Evaluation result about the resin composition of Comparative Example 1>
Except for using 20 g of the resin film prepared with the non-hydrophilic resin composition of Comparative Example 1, every time elapsed as in the case of using the resin film prepared with the hydrophilic resin composition of Example 1. The iodine ion concentration and cesium ion concentration in the solution were measured. The obtained results are shown in Table 6 and FIGS. 3 and 4 as in the case of Example 1 described above.

<Evaluation result about the resin composition of Comparative Example 2>
Except for using 20 g of the resin film prepared with the non-hydrophilic resin composition of Comparative Example 2, every time elapsed as in the case of using the resin film prepared with the hydrophilic resin composition of Example 1. The iodine ion concentration and cesium ion concentration in the solution were measured. The obtained results are shown in Table 7 and FIGS. 3 and 4 as in the case of Example 1 described above.

  As an application example of the present invention, radioactive iodine and radioactive cesium in radioactive liquid waste and / or radioactive solids can be removed easily and at low cost and without the need for an energy source such as electric power. By implementing the simultaneous removal method of iodine and radioactive cesium, it has become possible to easily and economically remove radioactive substances that have recently become a problem in waste liquids and solids. So its practical value is extremely high. Furthermore, in the technique of the present invention, the removed radioactive iodine and radioactive cesium can be taken in and stably immobilized in the hydrophilic resin composition comprising a hydrophilic resin having a specific structure and zeolite. Furthermore, since the main component is a resin composition, it is possible to reduce the volume of radioactive waste as necessary, which can also reduce problems with a large amount of radioactive waste that occurs after the removal of radioactive material. Expected to be used.

Claims (8)

In the radioactive iodine / radioactive cesium removal method, the radioactive iodine / radioactive cesium in the radioactive liquid waste and / or radioactive solids is removed using a hydrophilic resin composition comprising a hydrophilic resin composition and zeolite. There,
The hydrophilic resin composition has a hydrophilic segment and a hydrophilic group in the molecule, but is a resin insoluble in water and warm water, and has a main chain in the structure and / or Or at least one hydrophilic resin selected from the group consisting of a hydrophilic polyurethane resin, a hydrophilic polyurea resin, a hydrophilic polyurethane-polyurea resin having a tertiary amino group in the side chain, and
A method for removing radioactive iodine / radioactive cesium, wherein at least zeolite is dispersed at a ratio of 1 to 200 parts by mass with respect to 100 parts by mass of the hydrophilic resin.   The method for removing radioactive iodine / radioactive cesium according to claim 1, wherein the hydrophilic segment is a polyethylene oxide segment.   3. The resin according to claim 1, wherein the hydrophilic resin is a resin formed using a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group as a part of a raw material. To remove radioactive iodine and radioactive cesium. The method for removing radioactive iodine / radioactive cesium according to any one of claims 1 to 3, wherein the zeolite is a compound represented by the following general formula (1).

[In the formula (1), M ²⁺ is, Ca ^2+, Mn ^2+, is either Ba ²⁺ or Mg ^2+, M ⁺ is, Na ^+, K ⁺ or Li ⁺ either M is any number from 1 to 18, and n is any number from 1 to 70. ] A hydrophilic resin composition having a function capable of fixing either radioactive iodine or radioactive cesium in liquid and / or solid matter,
Including a hydrophilic resin and zeolite,
In the molecular chain, the hydrophilic resin is formed by using a polyol having at least one tertiary amino group or a polyamine having at least one tertiary amino group as a part of a raw material, A resin having a tertiary amino group, insoluble in water and warm water, and
A hydrophilic resin composition for removing radioactive iodine and radioactive cesium, wherein at least zeolite is dispersed at a ratio 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 either radioactive iodine or radioactive cesium in a liquid and / or solid matter,
Including a hydrophilic resin and zeolite,
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. It has a hydrophilic segment obtained by reacting a compound contained therein, and has a hydrophilic group in the molecule, but is a resin insoluble in water and warm water, and in the structure And having at least one tertiary amino group in the main chain and / or side chain, a hydrophilic polyurethane resin, a hydrophilic polyurea resin, a hydrophilic polyurethane-polyurea resin, and
A hydrophilic resin composition for removing radioactive iodine and radioactive cesium, wherein at least zeolite is dispersed at a ratio 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 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 zeolite is a compound represented by the following general formula (1).

[In the formula (1), M ²⁺ is, Ca ^2+, Mn ^2+, is either Ba ²⁺ or Mg ^2+, M ⁺ is, Na ^+, K ⁺ or Li ⁺ either M is any number from 1 to 18, and n is any number from 1 to 70. ]

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