JP2501831B2 - Cartridge for collecting radionuclides and heavy metals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cartridge for collecting radionuclides, heavy metals and the like.

[Prior art]

Radioactive waste liquid generated from nuclear power plants, radioisotope handling sites, etc. has various problems such as radiation exposure of workers, release of radioactivity to the surrounding environment, and storage of radioactive waste on the premises. There is an urgent need to establish technology for separating and removing waste liquid.

JP-A-60-260000 discloses that a ferrocyanate compound represented by the general formula K ₂ M ^II [Fe (CN) ₆ ] (M ^II is a divalent metal) is supported and fixed on an acrylic fiber. It is described that the radionuclide and the heavy metal scavenger are capable of capturing the radionuclide with high efficiency and reduced in volume at a high rate.

However, the following problems have been encountered when treating radioactive waste liquid using this trapping material. That is,
After collecting the collected material from the treatment system or leakage of radioactive waste liquid during its replacement, difficulty in replacing the collected material, and collection of the collected material during the work until the volume of the collected material is reduced. Poor handling in transportation and storage of gathering materials. Therefore, there is an urgent need to establish a practical use form of the above-mentioned trapping material having excellent radionuclide trapping performance.

[Problems to be solved by the invention]

The present invention enhances the collection performance of the above-mentioned collection material having excellent performance in collecting the radionuclide and improves the handling property during its use, prevents the leakage of radioactive waste liquid during its replacement, and It is also intended to improve the handling before the volume of the trapping material is reduced.

[Means for solving problems]

The present invention is a cartridge in which an acrylic fiber carrying 0.001 g or more of insoluble ferrocyanide per 1 g of fiber is filled in a cylinder having a treatment liquid inlet and an outlet, and the cylinder is made of a combustible synthetic resin. Provided is a cartridge for collecting radionuclides and heavy metals, wherein the acrylic fiber is an acrylic fiber whose surface is hydrolyzed with a base or an acid and which contains 0.1 to 5 mmol / g of carboxyl groups and / or sulfonic acid groups. It is a thing.

 Hereinafter, the present invention will be described in detail.

The acrylic fiber used in the present invention may be a fiber composed of a copolymer of two or more monomers containing acrylonitrile in an amount of 40% by weight or more, or an acrylonitrile homopolymer. Here, as the copolymerization component, acrylic acid, sodium methallyl sulfonate, sodium allyl sulfonate, sodium p-styrene sulfonate, acrylamide, methacrylamide, vinyl chloride, vinylidene chloride, vinyl acetate, methyl acrylate, N, N Examples thereof include, but are not limited to, '-dimethylaminoethyl acrylate and N, N'-diethylaminoethyl methacrylate. Further, the above acrylic fiber may be used as the acrylic fiber of the present invention after the surface thereof is hydrolyzed with a base such as sodium hydroxide or an acid such as sulfuric acid.

More preferably, acrylic fibers containing 0.1 to 5 mmol / g of carboxyl groups and / or sulfonic acid groups are used. Since the insoluble ferrocyanide is adsorbed on the acrylic fiber through the ionic interaction via the carboxyl group and / or the sulfonic acid group, the amount of the insoluble ferrocyanide attached increases. However, the total content of carboxyl groups and / or sulfonic acid groups is 0.1m
If it is less than mol / g, the amount of the insoluble ferrocyanide deposited will hardly increase, and if it is 5 mmol / g or more, the physical properties of the single yarn when it is used as a radionuclide and a heavy metal scavenger are markedly deteriorated. Result. Insoluble ferrocyanide has a solubility in water of 25 ℃, 0.1g / 100cc
It is a substance that is as follows and is composed of [Fe (CN) ₆ ] and a metal. For example, K ₂ Co [Fe (CN) ₆ ], Na ₂ Ni [Fe (C
N) ₆ ], K ₂ Zn ₃ [Fe (CN) ₆ ] ₂ , Cu ₂ [Fe (CN) ₆ ], Zn ₂
[Fe (CN) ₆ ], Cd ₂ [Fe (CN) ₆ ], Ni ₂ [Fe (C
N) _6], Fe ₄ [Fe (CN) _{6] 3,} Ti [Fe (CN) _6], can be cited such as metals, Li, K, Na, Ag , Zn, Cd, C
One or a combination of two or more of u, Co, Ni, Mn, Fe, Ti, Zr, V, Mo, W, U and the like can be used, but the present invention is not limited thereto. The loading of the insoluble ferrocyanide on the acrylic fiber is that the acrylic fiber itself surrounds the insoluble ferrocyanide, or that the carboxyl group and / or sulfonic acid group in the acrylic fiber and the insoluble ferrocyanide are adsorbed by ionic interaction. , Or by its synergistic effect, it is fixed to the acrylic fiber.

The amount of the insoluble ferrocyanide supported on the fiber may be 0.001 g or more per 1 g of the fiber, and if it is less than 0.001 g, the amount of the acrylic fiber necessary for adsorbing the radionuclide and the heavy metal is large, which is a practical problem. Is.

As a method for supporting the insoluble ferrocyanide on the acrylic fiber, for example, when spinning the acrylic fiber, there is a method in which the insoluble ferrocyanide is mixed with a stock solution for spinning and then a wet method or a dry method is used to carry out spinning by a conventional method. Examples of the spinning solvent include dimethylformamide, dimethylacetamide, dimethylsulfoxide, nitric acid, and an aqueous solution of rhodanate. In addition, for example, when spinning acrylic fibers, K ₄ [Fe (CN)] which is a water-soluble ferrocyanide is used.
₆ ], Na ₄ [Fe (CN) ₆ ] and the like are dissolved in water having a saturated solubility or higher and mixed with the spinning dope. After that, spinning is carried out by a conventional method using a wet method. One or two or more kinds of A are used so that the ferrocyanide becomes an insoluble ferrocyanide.
Examples of the method include adding metal ions or metal complexes such as g, Zn, Cd, Cu, Co, Ni, Mn, Fe, Ti, Zr, V, Mo, W, and U to a coagulation bath and spinning.

Further, for example, during spinning of acrylic fiber, one or more Ag, Zn, Cd, Cu, Co, Ni, Mn, and F, such that the ferrocyanide becomes an insoluble ferrocyanide in the spinning dope,
Metal ions such as e, Ti, Zr, V, Mo, W, and U, and metal complexes are dissolved in water having a saturated solubility or higher and mixed with the spinning dope. After that, spinning is carried out by a conventional method using a wet method. Water-soluble ferrocyanides such as K ₄ [Fe (CN) ₆ ], Na ₄ [Fe (CN)]
₆ ] and the like are added to the coagulation bath and spinning is performed.

Further, for example, an acrylic fiber is treated with an aqueous solution of a water-soluble ferrocyanide such as K ₄ [Fe (CN) ₆ ] or Na ₄ [Fe (CN) ₆ ] at a treatment temperature of 10 ° C. to 140 ° C. for a treatment time of 30 seconds or more.
The treatment is carried out in 3 hours. After that, one or more kinds of metals such as Ag, Zn, Cd, Cu, Co, Ni, Mn, Fe, Ti, Zr, V, Mo, W, U, etc., in which the ferrocyanide becomes an insoluble ferrocyanide. Treatment temperature 10 ° C with aqueous solution of ion or metal complex
A method of performing the treatment at 140 ° C. for 30 seconds to 3 hours can be mentioned.

In addition, for example, acrylic fibers are prepared from one or more kinds of Ag, Zn, Cd, Cu, Co, Ni, Mn, Fe, Ti, Zr, V, Mo, W in which the ferrocyanide becomes an insoluble ferrocyanide. Treatment temperature 10 with aqueous solution of metal ion or metal complex such as
The treatment is carried out at a temperature of 140 ° C to 140 ° C for 30 seconds to 3 hours. After that, K ₄ [Fe (C
N) ₆ ], Na ₄ [Fe (CN) ₆ ] or the like may be used at a treatment temperature of 10 ° C. to 140 ° C. for a treatment time of 30 seconds to 3 hours.

FIG. 1 is a longitudinal sectional view showing an example of a radionuclide- and heavy metal-collecting cartridge (hereinafter referred to as a cartridge) of the present invention. In FIG. 1, 1 is a cylindrical body, 2 is an inlet of the processing liquid provided in the cylindrical body, and 3 is an outlet of the processing liquid. Reference numeral 4 is an acrylic fiber (hereinafter referred to as the present collection material) which is filled in the cylindrical body 1 and carries the insoluble ferrocyanide.

In the cartridge shown in FIG. 1, when the collecting material filled in the cylindrical body 1 is an acrylic long fiber, the collecting material comes out of the cylindrical body 1 through the inlet 2 or the outlet 3 of the treatment liquid. It is preferable because it is less dangerous and has a simple structure.

The cartridge shown in FIG. 2 shows another embodiment in which the liquid permeable support 5 is installed inside the cylindrical body 1 close to the inlet 2 and the outlet 3 of the treatment liquid. The liquid-permeable support 5 has a function of fixing the trapping material 4 inside the cylindrical body 1, and is a non-woven fabric, a woven fabric, a perforated plate, a porous plate, or the like. In this embodiment, two liquid permeable supports 5 are provided close to the inlet 2 and the outlet 3 of the treatment liquid, but one or more liquid permeable supports may be provided. In this example, a short fibrous collecting material is used as the collecting material 4. In the case of a short fiber type collecting material, the collecting material is more likely to come out of the cylinder through the inlet and outlet of the treatment liquid than the long fiber type collecting material, but the treatment of the radioactive liquid containing the radioactive nuclide is performed. It is indispensable to install this liquid-permeable support because the collection material leaks into the outside of the tubular body. Further, the short fiber-like trapping material can increase the packing density in the cylinder and increase the processing capacity per cartridge, but on the other hand, the trapping material is unevenly distributed in the cylinder. Occurs, and it becomes difficult to uniformly fill. Such uneven distribution of the trapping material causes uneven flow of the processing liquid, resulting in a decrease in processing capacity. In order to solve such a problem, two or more liquid-permeable support members, preferably 3 to 10 are provided to divide the inside of the tubular body into several chambers and to collect the liquid-permeable support members between them. It is preferable to fill the material. The cartridge having the above structure can prevent uneven distribution of the trapping material and can increase the packing density of the trapping material. Further, the inlet and outlet of the treatment liquid and the mounting position of the water-permeable support are provided in the order from the inlet of the treatment liquid to the outlet thereof, the treatment liquid inlet, a plurality of liquid-permeable supports, and the treatment liquid outlet. The trapping material is filled between the liquid-permeable supports as described above.

Since the trapping material of the present invention is particularly suitable for volume reduction, the material of the tubular body 1, the liquid-permeable support 5 and the like is most preferably made of combustible resin and fibers. , Metal, ceramic, etc. may be used. As the material for forming the cylinder 1, synthetic resin such as polyethylene, polypropylene, and other polyolefins, polyester, polyamide, polyvinyl chloride, polyvinylidene chloride, poly (meth) acrylate, and the liquid-permeable support 5 can be used. Is acrylic fiber, polyester fiber, polyamide fiber, polyethylene fiber, polypropylene fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, rayon, bemberg,
Examples include non-woven fabrics made of various fibers such as acetate, cotton, hemp, and wool, cloths such as woven and knitted fabrics, porous plates made of the various synthetic resins described above, or sponge-like porous plates.

The cartridge of the present invention can be used by incorporating it into a liquid treatment system containing a radionuclide or a heavy metal, and can be used outside the treatment liquid system in each operation step such as attachment of a trapping material, replacement, and volume reduction treatment. There is a remarkable effect in reducing the risk of leaks from workers, exposure to workers, and ensuring safer work and the environment.

〔Example〕

Example 1 (1) Production of Scavenger Material 4 kg of 3 denier acrylic fiber having a copolymer composition of acrylonitrile = 91.5% by weight, methyl acrylate = 8% by weight, and sodium methallylsulfonate = 0.5% by weight.
To the above, 3N aqueous sodium hydroxide solution 40 is added, and the reaction is carried out at a reaction temperature of 50 ° C. for 1 hour using an Overmeier type dyeing machine. After the reaction, the washing is repeated until the washing water has a pH of 7.0 (the content of carboxyl groups and sulfonic acid groups in the obtained fiber was 2.3 mmol / g). In addition, 1
40% of 0 wt% cobalt nitrate aqueous solution was added, and the treatment temperature was 6
Process at 0 ° C. for 1 hour using an Overmeier dyeing machine. After the treatment, the washing is repeated until the coloring of the washing water disappears. Then, 10 wt% potassium ferrocyanate aqueous solution 40 is added, and the treatment is performed at a treatment temperature of 60 ° C. for 1 hour using an Overmeier type dyeing machine. After the treatment, the washing was repeated until the coloring of the washing water disappeared and then dried at 70 ° C. for 3 hours.

(2) Manufacture of cartridge 1) The above-mentioned trapping material is well disentangled without being cut and divided into single yarns, and then 100 g of this trapping material is filled into a cylinder made of polypropylene having an inner diameter of 5 cm and a height of 15 cm. I made a Cartridge.

2) The above collecting material was cut into a length of 10 mm and divided into single fibers. A liquid-permeable support made of polypropylene non-woven fabric with a thickness of 5 mm is provided in a cylinder with an inner diameter of 5 cm at intervals of 15 cm,
100 g of the collecting material was filled between the liquid-permeable supports. The short fibrous collecting material was filled almost uniformly without uneven distribution.

(3) Cartridge performance and handling test A 2% sodium sulfate solution was added to the above two types of cartridges.
A pH 7.3 solution containing 5 ppm of cesium and 5 ppm of copper was passed at room temperature (about 2.0 ° C.) at a rate of 700 / hour. As a result, neither cesium nor copper was detected in the treated solution until the 70 treated solutions passed. After that, the concentration of cesium and copper in the solution after the treatment increased rapidly.

If there is a drift of the treatment liquid in the cartridge, it is possible to detect cesium and copper in the treated solution at an early stage, and at the same time, the concentration of them may gradually increase. It was found that the scavenger was uniformly filled.

Further, although the above-described processing operation was continuously performed for a long period of time while the cartridge was replaced, the cartridge was replaced and installed very easily. In addition, at that time, the processing liquid did not leak.

Further, the treated cartridges can be directly volume-reduced, and the transportation and storage until the volume-reduction treatment can be performed very safely.

〔The invention's effect〕

The cartridge according to the present invention is very easy to install and replace in the processing system, the processing solution does not leak during the installation and replacement, and the cartridge is transported after processing.
It is easy to store temporarily and is suitable for volume reduction. For this reason, it is most suitable for waste treatment of radioactive isotope facilities such as nuclear power plants, nuclear fuel reprocessing plants, hospitals, and laboratories.

[Brief description of drawings]

1 and 2 are sectional views showing examples of the cartridge according to the present invention. 1 ... Cylinder, 2 ... Processing liquid inlet, 3 ... Processing liquid outlet, 4
... Acrylic fiber carrying insoluble ferrocyanide,
5: Liquid-permeable support.

Claims (1)

(57) [Claims] 1. A cartridge comprising an inside of a cylindrical body having an inlet and an outlet of a treatment liquid and an acrylic fiber carrying 0.001 g or more of an insoluble ferrocyanide per 1 g of the fiber, the cylindrical body being flammable. A cartridge for collecting radionuclides and heavy metals, which is composed of a resin, and the acrylic fiber is an acrylic fiber whose surface is hydrolyzed with a base or an acid and which contains 0.1 to 5 mmol / g of a carboxyl group and / or a sulfonic acid group.