JP2022511035A - Radioactive cesium decontamination agent and radioactive cesium decontamination method that can be adjusted according to the water depth using this - Google Patents

Abstract

The present invention is a composition containing a clay mineral and a foaming agent, which can adsorb or remove radioactive cesium in water and adjust the foaming rate according to the water depth by adjusting the content of the clay mineral and the foaming agent. Provide a cesium decontamination agent. The present invention, after all, includes a technical idea to maximize the horizontal dispersion performance by adjusting the sedimentation rate of zeolite, which is a radioactive cesium decontamination agent, and is new in the field of decontamination of radioactive cesium in water. Present the model. [Selection diagram] FIG. 8d

Description

This technique relates to a technique for decontaminating pollutants in water, and in particular, a technique related to a decontamination agent and a decontamination method capable of efficiently decontaminating radioactive cesium existing in water at various water depths.

Due to the accident at the Japan Fukushima Nuclear Power Station in March 2011, soil, animals and plants, waste, etc. are contaminated with radioactive substances, causing serious environmental problems. Radioiodine and radioactive cesium can be mentioned as the main radioactive substances generated in the event of a nuclear power plant accident. Radioiodide has a relatively short half-life of about 8 days, whereas radioactive cesium has a very long half-life of 30 years, and cesium has similar chemical properties to potassium during absorption. It is concentrated in muscles and causes deficiency of immunity and induces various cancers (infertility, myeloma, lung cancer, thyroid cancer, breast cancer, etc.).

Minerals such as zeolite must be in direct contact with contaminants in order to remove contaminants such as radioactive cesium. If radioactive cesium flows into a place with a fixed capacity such as a water purification plant, there is no problem with the contact between zeolite and cesium, but in places such as lakes where the capacity is not fixed, on the water surface. Depending on the spraying of, contact limits may occur. In addition, since the specific gravity of zeolite is 2.0 to 2.4, the sedimentation rate is high in water, and it may not be possible to have a sufficient residence time to react with radioactive cesium. In addition, in relatively large fresh water such as Lake Hachido, the maximum depth is 23 m, and the average depth is 6 m. There is also the possibility that it is not distributed.

In the present invention, the decontaminating agent is effectively dispersed in the horizontal direction with a sufficient residence time in a situation where the contaminants can be distributed unevenly depending on the depth according to the scale of the water system. The present invention is an invention devised to solve the problems of the prior art, and an object of the present invention is to provide a radioactive cesium decontaminating agent capable of adjusting radioactive cesium according to the water depth to decontaminate.

Another object of the present invention is to provide a method for decontaminating radioactive cesium, which can efficiently decontaminate radioactive cesium in water according to the water depth by using the radioactive cesium decontaminating agent.

Hereinafter, various specific examples described in the present application will be described with reference to the drawings. In the following description, various specific details, such as specific forms, compositions and processes, are described for a complete understanding of the invention. However, certain embodiments may be performed without one or more of these specific details or in conjunction with other known methods and forms. In other examples, known processes and manufacturing techniques are not described as specific details so as not to unnecessarily obscure the invention. References throughout the specification to a "specific example" or "specific example" are examples of one or more embodiments of the invention in which the particular features, shapes, compositions or properties described in connection with the embodiment. Means to be included in. Therefore, the "in one embodiment" or "specific example" situation expressed at various positions throughout the specification does not necessarily indicate the same embodiment of the present invention. In addition, special features, shapes, compositions or properties may be combined by any suitable method, as described in one or more specific examples.

Unless otherwise defined within the invention, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art in the art to which the invention belongs. ..

In the present invention, the "radioactive substance" is a main pollutant generated at the time of a serious nuclear accident. In today's widely used nuclear power plants, fission in a nuclear reactor involves the production of significant amounts of radioactive by-products. As the radioactive substances, the main ones of these radioactive substances are iodine 131, cesium 134, cesium 137, cerium 144, rhodium 106, cobalt 60, strontium 90, radium 226, uranium 234, uranium 235, uranium 238, and plutonium 239. Fission products and active elements containing extremely dangerous radioisotopes such as, but are not limited to.

In the present invention, the contaminated water can mean an aqueous solution in which a radioactive substance is dissolved. In the event of a serious nuclear accident, highly volatile radioactive materials may vaporize and move into the atmosphere early in the serious accident and flow into the surface environment through fallout or rainfall. In the contaminated water, radioactive substances such as radioactive cesium may be dissolved in ionic form or may be contained in a strong bond with clay and organic matter.

In the present invention, zeolite is a group of minerals belonging to reticulated silicate minerals, has a large number of pores of several nanometers inside, and has high removal efficiency for various pollutants. Are known. It can absorb and remove water and malodor, can capture heavy metals, and can also be used as a material for ion exchangers. In particular, natural zeolites are collected in the form of "zeolitic tuff", which is an altered form of almost fine-grained tuff, and are positive for Na, K, Ca, Mg, Sr or Ba in terms of chemical composition. Hydrous silicate minerals containing a small amount of ions, the types of which are clinoptilolite, mordenite, heulandite, phillipsite, erionite, and the like. There are, but are not limited to, chabazite and ferrierite.

In the present invention, sodium hydrogen carbonate may generate voids or pores due to the generation of HCO ₃ gas in the process of decomposition by heat during drying, and Na ⁺ may remain in the adsorbent even after firing to help form structural force. can. Further, in the process of forming the voids or pores, the natural zeolite, citric acid, and corn starch can play a role of adhering or adhering to the adsorbent of the present invention without a film.

The corn starch of the present invention may be, but is not limited to, amylose-containing starch extracted from corn. Alternatively, starch formulations such as high amylose corn starch and corn starch formulations may be used. The maize of the present invention is obtained in its natural state or by standard mating techniques including mating breeding, translocation, inversion, transformation or any other gene or chromosomal manipulation method including these mutations. It may be, but it is not limited to this.

The starches of the present invention are produced by, but are not limited to, physical treatment steps including extrusion, total compression, cooking of starch slurries, spray drying and fluidized bed aggregation. In one embodiment, the step may be an extrusion step. The starch is treated to partially gelatinize to produce starch particles with gelatinized and non-gelatinized moieties. In one embodiment, the gelatinized starch binds together essentially non-gelatinized particles (ie, granules). In the present invention, corn starch can serve to keep the dosage form of the decontamination agent constant.

According to one embodiment of the present invention, the decontaminating agent for removing radioactive substances contained in contaminated water relates to a decontaminating agent for radioactive contaminants including zeolite; sodium hydrogen carbonate; and citric acid.

In the present invention, the decontamination agent may contain 30 to 60% by weight of zeolite; 20 to 40% by weight of sodium hydrogen carbonate; and 10 to 40% by weight of citric acid, but is limited thereto. is not it.

In the present invention, the decontamination agent contains 40 to 60% by weight of zeolite; 20 to 40% by weight of sodium hydrogen carbonate; and 10 to 20% by weight of citric acid, for removing radioactive substances contained in the middle layer water system. It may be, but it is not limited to this.

In the present invention, the decontamination agent contains 30 to 40% by weight of zeolite; 30 to 40% by weight of sodium hydrogen carbonate; and 20 to 40% by weight of citric acid, for removing radioactive substances contained in a deep water system. It may be, but it is not limited to this.

In the present invention, the decontamination agent may further contain corn starch, and preferably the corn starch may be 5 to 20% by weight, but is not limited thereto. ..

In the present invention, the decontaminating agent may contain zeolite, sodium hydrogen carbonate, citric acid and corn starch in a weight ratio of 2: 1 to 2: 0.5 to 1: 0.25 to 1. However, it is not limited to this.

In the present invention, the decontamination agent may contain zeolite, sodium hydrogen carbonate, citric acid and corn starch in a weight ratio of 2: 1: 0.5: 0.5, or the decontamination agent. May be for removing radioactive substances contained in the middle layer water system, but is not limited thereto.

In the present invention, the decontamination agent contains zeolite, sodium hydrogen carbonate, citric acid and corn starch in a weight ratio of 2: 1: 0.5: 0.25, and the decontamination agent is a deep water system. It may be for removing radioactive substances contained in, but is not limited to this.

In the present invention, the zeolite may contain 50 to 60% by weight of heulandite and 40 to 50% by weight of heulandite, but is not limited thereto.

In the present invention, the zeolite has a specific surface area of 50 to 70 m ² / g, an average void volume of 0.1 to 0.15 ml / g, and an average void size of 5 to 15 nm. The cation exchange capacity may be 60 to 120 meq / 100 g, but is not limited thereto.

The radioactive cesium decontamination agent according to an embodiment of the present invention contains a clay mineral such as zeolite for adsorbing radioactive cesium, and at the same time contains a foaming component, and the content of the clay mineral and the foaming component. For adjustment, the foaming rate of the decontamination agent can be adjusted. This makes it possible to adjust the onset rate and fulcrum of the decontamination effect according to various depths or water depths, and enable decontamination that can be adjusted according to various water depths in the water system. This means that, after all, it is possible to decontaminate the radioactive cesium contamination source existing in all the water depths, and thereby the decontamination efficiency of the radioactive cesium in the water can be maximized.

Therefore, when the decontamination agent is sprayed on various horizontal regions in a water system contaminated with radioactive cesium and at the same time spraying decontamination agents having various compositions, a uniform decontamination effect is exhibited in the horizontal and vertical regions. be able to.

However, the unit weight, unit capacity, etc. of the decontamination agent can be variously deformed in consideration of the capacity, area, water depth, etc. of the water system.

The present invention, after all, includes the technical idea of maximizing the horizontal dispersion performance by adjusting the sedimentation rate of zeolite, which is a radioactive cesium decontamination agent, and is new in the field of decontamination of radioactive cesium in water. Present the model.

FIG. 1a is a graph showing the results of X-ray diffraction analysis on a zeolite (ZG) sample, and FIG. 1b is a graph showing the results of X-ray diffraction analysis on a Gyeongju-produced zeolite (KGZ) sample. FIG. 1c. Is a graph showing the results of X-ray diffraction analysis on a zeolite (KPZ) sample produced in Urano. It is a graph which showed the result of the low-concentration cesium (Cw≈50 μg / L) adsorption partition coefficient for various clay minerals. It is a schematic diagram which showed the large column water tank. It is a graph which showed the result of the preliminary experiment of a 40L water tank. 5a to 5f are graphs showing changes in turbidity concentration over time due to the zeolite powder type decontamination agent. FIG. 5a is a graph showing the change in turbidity concentration after 1 minute by the zeolite powder type decontamination agent, and FIG. 5b is a graph showing the change in turbidity concentration after 3 minutes by the zeolite powder type decontamination agent. FIG. 5c is a graph showing the change in turbidity concentration after 10 minutes due to the zeolite powder type decontamination agent, and FIG. 5d shows the change in turbidity concentration after 60 minutes due to the zeolite powder type decontamination agent. 5d is a graph showing the change in turbidity concentration after 120 minutes due to the zeolite powder type decontamination agent, and FIG. 5f is a graph showing the change in turbidity concentration after 1440 minutes due to the zeolite powder type decontamination agent. It is a graph shown. 6a to 6f are graphs showing changes in cesium concentration over time due to the zeolite powder type decontamination agent. FIG. 6a is a graph showing the change in cesium concentration after 1 minute by the zeolite powder type decontamination agent, and FIG. 6b is a graph showing the change in cesium concentration after 3 minutes by the zeolite powder type decontamination agent. FIG. 6c is a graph showing the change in cesium concentration after 10 minutes by the zeolite powder type decontamination agent, and FIG. 6d is a graph showing the change in cesium concentration after 60 minutes by the zeolite powder type decontamination agent. FIG. 6d is a graph showing the change in cesium concentration after 120 minutes by the zeolite powder type decontamination agent, and FIG. 6f is a graph showing the change in cesium concentration after 1440 minutes by the zeolite powder type decontamination agent. 7a to 7f are graphs showing changes in turbidity concentration over time due to the decontamination agent of Example 1. FIG. 7a is a graph showing the change in turbidity concentration after 1 minute by the decontamination agent of Example 1, and FIG. 7b shows the change in turbidity concentration after 3 minutes by the decontamination agent of Example 1. 7c is a graph showing the change in turbidity concentration after 10 minutes by the decontamination agent of Example 1, and FIG. 7d is a graph showing the turbidity concentration after 60 minutes by the decontamination agent of Example 1. It is a graph showing the change, FIG. 7d is a graph showing the change in turbidity concentration after 120 minutes by the decontamination agent of Example 1, and FIG. 7f is a graph showing the change in turbidity concentration after 1440 minutes by the decontamination agent of Example 1. It is a graph which showed the turbidity concentration change of. 8a to 8f are graphs showing changes in cesium concentration over time due to the decontamination agent of Example 1. FIG. 8a is a graph showing the change in cesium concentration after 1 minute by the decontamination agent of Example 1, and FIG. 8b is a graph showing the change in cesium concentration after 3 minutes by the decontamination agent of Example 1. FIG. 8c is a graph showing the change in cesium concentration after 10 minutes by the decontamination agent of Example 1, and FIG. 8d shows the change in cesium concentration after 60 minutes by the decontamination agent of Example 1. 8d is a graph showing the change in cesium concentration after 120 minutes due to the decontamination agent of Example 1, and FIG. 8f shows the change in cesium concentration after 1440 minutes due to the decontamination agent of Example 1. It is a graph shown. 9a to 9f are graphs showing changes in turbidity concentration over time due to the decontamination agent of Example 2. FIG. 9a is a graph showing the change in turbidity concentration after 1 minute by the decontamination agent of Example 2, and FIG. 9b shows the change in turbidity concentration after 3 minutes by the decontamination agent of Example 2. 9c is a graph showing the change in turbidity concentration after 10 minutes by the decontamination agent of Example 2, and FIG. 9d is a graph showing the turbidity concentration after 60 minutes by the decontamination agent of Example 2. 9d is a graph showing the change, and FIG. 9d is a graph showing the change in turbidity concentration after 120 minutes by the decontamination agent of Example 2, and FIG. 9f is a graph showing the change in turbidity concentration after 1440 minutes by the decontamination agent of Example 2. It is a graph which showed the turbidity concentration change of. 10a to 10f are graphs showing changes in cesium concentration over time due to the decontamination agent of Example 2. FIG. 10a is a graph showing the change in cesium concentration after 1 minute by the decontamination agent of Example 2, and FIG. 10b is a graph showing the change in cesium concentration after 3 minutes by the decontamination agent of Example 2. FIG. 10c is a graph showing the change in cesium concentration after 10 minutes by the decontamination agent of Example 2, and FIG. 10d shows the change in cesium concentration after 60 minutes by the decontamination agent of Example 2. 10d is a graph showing the change in cesium concentration after 120 minutes due to the decontamination agent of Example 2, and FIG. 10f shows the change in cesium concentration after 1440 minutes due to the decontamination agent of Example 2. It is a graph shown. FIG. 11a shows an example of a dosage form of the decontamination agent of Examples 1 and 2, and FIG. 11b shows an embodiment of the dosage form of the decontamination agent of Examples 3 and 4. An example is shown. 12a to 12d show the time-dependent dispersion pattern of the decontamination agent of Example 3. FIG. 12a shows the dispersion mode 2 seconds after the administration of the decontamination agent of Example 3, and FIG. 12b shows the dispersion 8 seconds after the administration of the decontamination agent of Example 3. The mode is shown, FIG. 12c shows the dispersion mode 20 seconds after the administration of the decontamination agent, and FIG. 12d shows the dispersion mode 40 seconds after the administration of the decontamination agent of Example 3. It shows the state of dispersion after the lapse of time. 13a to 13d show the time-dependent dispersion pattern of the decontamination agent of Example 4. FIG. 13a shows the dispersion mode 2 seconds after the administration of the decontamination agent of Example 4, and FIG. 13b shows the dispersion 5 seconds after the administration of the decontamination agent of Example 4. The mode is shown, FIG. 13c shows the dispersion mode 20 seconds after the administration of the decontamination agent of Example 4, and FIG. 13d shows the administration of the decontamination agent of Example 4. After that, it shows the dispersion mode after 40 seconds have passed. 14a to 14c show the time-dependent dispersion pattern of the decontamination agent of Comparative Example 11. FIG. 14a shows the dispersion mode 4 seconds after the administration of the decontamination agent of Comparative Example 11, and FIG. 14b shows the dispersion 20 seconds after the administration of the decontamination agent of Comparative Example 11. The mode is shown, and FIG. 14c shows the dispersion mode 60 seconds after the administration of the decontamination agent of Comparative Example 11. 15a to 15c show the time-dependent dispersion pattern of the decontamination agent of Comparative Example 12. FIG. 15a shows the dispersion mode 2 seconds after the administration of the decontamination agent of Comparative Example 12, and FIG. 15b shows the dispersion 5 seconds after the administration of the decontamination agent of Comparative Example 12. The mode is shown, and FIG. 15c shows the dispersion mode 70 seconds after the administration of the decontamination agent of Comparative Example 12. 16a to 16d show the time-dependent dispersion pattern of the decontamination agent of Comparative Example 13. FIG. 16a shows the dispersion pattern 4 seconds after the administration of the decontamination agent, and FIG. 16b shows the dispersion pattern 8 seconds after the administration of the decontamination agent of Comparative Example 13. FIG. 16c shows the dispersion mode 20 seconds after the administration of the decontamination agent. In FIG. 17a, a decontaminating agent having the same compounding ratio as in Example 3 and produced in a dosage form of 10 g is dropped into two water tanks having different temperatures of 0 ° C. (left) and 20 ° C. (right), and then. It shows how 15 seconds have passed. FIG. 17b shows 15 seconds after dropping the decontamination agent produced in 12 g having the same compounding ratio as in Example 4 into two water tanks having different temperatures of 0 ° C (left) and 20 ° C (right). It shows how it has passed. FIG. 18a is an embodiment of the present invention, and shows the desorption rate divided into low concentration and high concentration from 14 days to about 70 days in order to investigate the time-dependent desorption effect of illite depending on the temperature and concentration. Is. FIG. 18b is an embodiment of the present invention, and shows the desorption rate divided into low concentration and high concentration from 14 days to about 70 days in order to investigate the time-dependent desorption effect of zeolite depending on the temperature and concentration. Is.

According to one embodiment of the present invention, the decontaminating agent for removing radioactive substances contained in contaminated water relates to a decontaminating agent for radioactive contaminants including zeolite; sodium hydrogen carbonate; and citric acid.

Hereinafter, the radioactive cesium decontamination agent of the present invention and the method for decontaminating radioactive cesium that can be adjusted according to the water depth using the same will be described in detail through the attached drawings, experimental materials, and the like. However, the following description is an exemplary description to aid in the understanding of the present invention, and the technical idea of the present invention is not limited by the following description. However, the technical idea of the present invention can be interpreted or limited by the scope of claims described later.

[Preparation example] Preparation of sample for decontamination agent A natural zeolite sample (ZG) was selected as the basic material for the radioactive cesium decontamination agent. FIG. 1a is a graph showing the results of X-ray diffraction analysis on a zeolite (ZG) sample. As the origin of zeolite, samples produced in Gyeongju Gyeongju area were selected. Among the commercially available Gyeongju zeolite (KGZ) products, the most widely sold product with a particle size of 45 μm was purchased. In addition, Table 1 below is a table showing the composition ratios of the constituent components (minerals) confirmed by the results of the diffraction analysis. With reference to FIG. 1a and Table 1, it was confirmed through X-ray diffraction analysis that heulandite and mordenite, which are minerals belonging to zeolite, were composed, and the composition ratio was about 53% heulandite and morden. Zeolites consisted of about 47%.

Pohang zeolite (KPZ) produced in Pohang, preferably Pohang Yeongil Bay, is also composed entirely of heulandite and mordenite, and has similar characteristics to Gyeongju zeolite (KGZ). FIG. 1b is a graph showing the results of X-ray diffraction analysis on a zeolite sample produced in Gyeongju, and FIG. 1c is a graph showing the results of X-ray diffraction analysis on a zeolite sample produced in Pohang. As shown in Table 1, the Gyeongju-produced zeolite and the Pohang-produced zeolite have slightly different composition ratios, but the results of the X-ray diffraction analysis showed substantially similar peak morphology (FIGS. 1b and 1c). Zeolites have a specific surface area of about 60 m ² / g, a very small particle size, and a cation exchange capacity of about 72 to 100 meq / 100 g. It showed a very high value compared to (Table 2). In particular, the specific surface area and the cation exchange capacity can act as factors that affect the difference in adsorption capacity.

Mineralogical Properties of Zeolite (ZG) Samples Table 2 shows the results of evaluating the mineralogical properties of the prepared zeolite samples. FIG. 2 is a graph showing the results of low-concentration cesium (Cw≈50 μg / L) adsorption and partition coefficient for various clay minerals. Table 3 is a table showing the quantified adsorption partition coefficient of each mineral. Referring to Table 2, Table 3 and FIG. 2, the specific surface area of ZG was about 65 m ² per 1 g, and the cation exchange capacity was about 100 meq / 100 g, which were high. As a result of a small-scale adsorption experiment conducted using 50 mL vial, the partition coefficient (K _d ) for cesium is about 600,000 L / kg, which is very high, which is higher than that of other minerals. It was about 100 to 1000 times higher. The main adsorption mechanism that occurs in zeolite is the cation exchange reaction that occurs in the voids, and it can be interpreted that the high specific surface area and cation exchange capacity of zeolite contributed to increasing the cesium removal rate of zeolite.

FIG. 18a is an embodiment of the present invention, and shows the desorption rate divided into low concentration and high concentration from 14 days to about 70 days in order to investigate the time-dependent desorption effect of illite depending on the temperature and concentration. Is.

FIG. 18b is an embodiment of the present invention, and shows the desorption rate divided into low concentration and high concentration from 14 days to about 70 days in order to investigate the time-dependent desorption effect of zeolite depending on the temperature and concentration. Is.

As a result of investigating the time-dependent desorption effects of illite and zeolite depending on the concentration, it can be seen that the degree of desorption of the two minerals does not change significantly with time, and that desorption occurs almost at the initial stage of the reaction. Illite had a desorption rate of about 20% at a low concentration and about 50% at a high concentration, and no difference in desorption characteristics depending on the temperature was observed. The point to be peculiar was that the attachment / detachment rate tended to increase slightly with time at high concentrations. Zeolites had a relatively low concentration and a high desorption rate, but in all cases the desorption rate was less than 1%, showing very excellent adsorption stability.

In this preparation example, only zeolite is exemplified as the clay mineral used for the decontamination agent, but the use of other minerals such as illite, bentonite, and sericite is also within the scope of the technical idea of the present invention. That is natural. Further, depending on the applicable water system, a plurality of kinds of mixed minerals may be used as the mineral.

On- site copying experiment In the existing laboratory experiment to confirm the adsorption efficiency of cesium using natural minerals such as zeolite, zeolite and cesium in the vial can be formed by continuous stirring using a small volume 50 mL vial. I tried to react as uniformly as possible. Such a method has an advantage that the theoretical maximum cesium adsorption performance (Qm, single plane maximum adsorption amount, Langmir model) and adsorption efficiency can be obtained. However, in the actual field where a decontamination agent such as zeolite is sprayed, 100% contact is not possible as in the experimental environment, so in order to confirm the efficiency with respect to the scale in this way, 1 ton scale. I made a large transparent water tank and experimented with it. FIG. 3 is a schematic view showing a large column water tank. With reference to FIG. 3, in order to confirm the dispersity of the decontamination agent and the cesium removal efficiency according to the distance and depth in the spraying area in the water tank, a sampling pipe was manufactured and provided with acrylic. The diameter of the sampling pipe is 20 mm (inner diameter 14 mm), and the total length of the sampling pipe is 1.7 m. After separating 5 cm from the bottom so that the water quality sample could flow in in units of 30 cm, a screen having a length of 5 cm was provided after drilling a total of 4 sections at intervals of 30 cm. After filling the water tank with 1 ton of water, the main cations (Ca, Mg, Na and K) and the main anions (Cl, SO ₄ , HCO) are to reflect the competitive ion effects that can occur in the actual field. ₃ ) was added to adjust the water quality to be similar to the water quality of Lake Hachido, which is the site to be copied, and homogenized with low-concentration cesium (about 50 μg / L). After that, a decontamination agent was added and the turbidity and cesium removal efficiency were confirmed.

Before spraying the decontamination agent, use a metering pump (Peristaltic Pump) to collect a water quality sample to check the initial water quality, and then add the decontamination agent to check the change over time. Was collected. At the time of sample collection, about 25 mL was collected at a time at a flow rate of 15 mL / min. The turbidity of the sample was first measured, then placed in a centrifuge and centrifuged at 3500 rpm for 30 minutes, and then the supernatant was collected. The pH of the supernatant was lowered to 2 or less using nitric acid, stored at 4 ° C. or lower, and the cesium concentration was measured by ICP-MS.

The nuclides of cesium that can be used in this experiment are not limited. Since one factor in the movement of radionuclides in the aquatic environment is the behavior of stable nuclides, the stable behavior of cesium in the aquatic environment is probably to predict the long-term effects of cesium-137 on the environment. This is because can be used as a metaphor (Tiwari, Diwakar & Lalhmunsiama, Lalhmunsiama & Choi, S & Lee, Seung-Mok (2014) .Activated Sericite:. An Efficient and Effective Natural Clay Material for Attenuation of Cesium from Aquatic Environment.Pedosphere24. 731-742.).

Powder type decontamination agent (powder type zeolite alone)
Prior to the 1-ton scale large tank experiment, a preliminary experiment was conducted in a 40 L scale water tank in order to calculate the appropriate amount of zeolite required to remove radioactive cesium in the water. As a result of the preliminary experiment, considering both the turbidity and the cesium removal rate, cesium was removed most efficiently when 2 g of zeolite was added at 40 L, so this was selected as the basic design quantity. FIG. 4 is a graph showing the results of a preliminary experiment of a 40 L water tank. The zeolite requirement for a 1-ton scale aquarium calculated based on this was 50 g.

Using the results of the preliminary experiment, 50 g of zeolite powder was placed in a water tank filled with 1 ton of cesium-contaminated water, and then the turbidity and cesium concentration by time, position, and depth were measured. 5a to 5f are graphs showing changes in turbidity concentration over time due to the zeolite powder type decontamination agent. FIG. 5a is a graph showing the change in turbidity concentration after 1 minute by the zeolite powder type decontamination agent, and FIG. 5b is a graph showing the change in turbidity concentration after 3 minutes by the zeolite powder type decontamination agent. FIG. 5c is a graph showing the change in turbidity concentration after 10 minutes due to the zeolite powder type decontamination agent, and FIG. 5d shows the change in turbidity concentration after 60 minutes due to the zeolite powder type decontamination agent. 5d is a graph showing the change in turbidity concentration after 120 minutes due to the zeolite powder type decontamination agent, and FIG. 5f is a graph showing the change in turbidity concentration after 1440 minutes due to the zeolite powder type decontamination agent. It is a graph shown.

Referring to FIGS. 5a-5f, the zeolite powder reached the bottom of the aquarium within 1 minute and was more likely to settle vertically than to disperse horizontally.

6a to 6f are graphs showing changes in cesium concentration over time due to the zeolite powder type decontamination agent. FIG. 6a is a graph showing the change in cesium concentration after 1 minute by the zeolite powder type decontamination agent, and FIG. 6b is a graph showing the change in cesium concentration after 3 minutes by the zeolite powder type decontamination agent. FIG. 6c is a graph showing the change in cesium concentration after 10 minutes by the zeolite powder type decontamination agent, and FIG. 6d is a graph showing the change in cesium concentration after 60 minutes by the zeolite powder type decontamination agent. FIG. 6d is a graph showing the change in cesium concentration after 120 minutes by the zeolite powder type decontamination agent, and FIG. 6f is a graph showing the change in cesium concentration after 1440 minutes by the zeolite powder type decontamination agent.

With reference to FIGS. 6a to 6f, it was confirmed that the concentration of cesium in the water also decreased along the fulcrum where the turbidity increased, and that the decontamination effect was concentrated around the zeolite. This tendency was strong during the first 1-3 minutes of the experiment, after 3 minutes all the zeolite powder reached the bottom, and after 10 minutes the turbidity was homogenized first. After that, it was confirmed that the cesium concentration in the water was gradually homogenized. After 24 hours, the zeolite particles have sunk to the bottom to the extent that it is difficult to recover by collecting water through a metering pump. At this time, the final cesium removal rate is about 60%, and at all fulcrums. It was similar.

Decontamination agent that can be adjusted according to the depth When the above-mentioned powdered zeolite was charged into the water tank, it was confirmed that vertical dispersion was predominant due to sedimentation at the initial stage of charging, and horizontal dispersion was hardly performed. When spraying a decontamination agent over a large area, a low horizontal dispersion of the decontamination agent has the disadvantage of having to have more input fulcrums. As components for effervescence, sodium hydrogen carbonate (NaHCO ₃ ) and citric acid (C ₆ H ₈ O ₇ ) express the expression of zeolite, which is a decontamination component, by increasing the horizontal dispersion and adjusting the effervescence rate. It is an ingredient that can be adjusted.

[Example 1] Production of radioactive cesium decontamination agent (for deep layers)
In the foam decontamination agent, the main additives, sodium hydrogen carbonate, citric acid, and zeolite are mixed at the contents shown in Table 4, and ethanol (C ₂ H ₅ OH) is used to form these. It was used. The amount of zeolite charged based on 1 ton was set to 50 g as in the result of the preliminary experiment, and the same was applied. Ethanol for mixing and molding zeolite and other accompanying materials is injected inside and outside 20% of the total decontamination agent mass, placed in a production frame and dried in an oven set at 40 ° C for 2 days or more. Manufactured a decontamination agent. As a result of comparing the weights of the finally produced decontamination agents, a mass loss of about 20% inside and outside occurred in the process of production and drying. The final dosage form was to have the form of pellets or tablets.

[Comparative Examples 1 to 5] Production of radioactive cesium decontamination agent (outside the deep layer)
The decontamination agent was produced by the same method as in Example 1, but the decontamination agents of Comparative Examples 1 to 5 were produced according to the composition ratios shown in Table 4 below.

Analysis of dispersion in water and decontamination tendency In order to remove cesium in water, decontamination agents (Example 1, Comparative Examples 1 to 5) produced at different blending ratios were placed in a water tank, and then settled and dispersed. The tendency was observed, and the turbidity and the concentration of cesium according to the position and depth of the decontamination agent of Example 1 having the best dispersion tendency were measured and shown.

7a to 7f are graphs showing changes in turbidity concentration over time due to the decontamination agent of Example 1. FIG. 7a is a graph showing the change in turbidity concentration after 1 minute by the decontamination agent of Example 1, and FIG. 7b shows the change in turbidity concentration after 3 minutes by the decontamination agent of Example 1. 7c is a graph showing the change in turbidity concentration after 10 minutes by the decontamination agent of Example 1, and FIG. 7d is a graph showing the turbidity concentration after 60 minutes by the decontamination agent of Example 1. It is a graph showing the change, FIG. 7d is a graph showing the change in turbidity concentration after 120 minutes by the decontamination agent of Example 1, and FIG. 7f is a graph showing the change in turbidity concentration after 1440 minutes by the decontamination agent of Example 1. It is a graph which showed the turbidity concentration change of.

Referring to FIGS. 7a to 7f, unlike the powder type decontamination agent in which sedimentation occurs only in the vertical direction without horizontal dispersion, horizontal dispersion occurs greatly while the decontamination agent dissolves from about 60 cm below the water surface. It was confirmed that the sediment was settled after spreading. The overall settling was similar to that of the powder type decontamination agent, but the settling occurred rapidly, but the dispersion occurred much wider in the horizontal direction than in the powder type. It was possible to confirm the floating zeolite particles even when about 60 minutes had passed after the decontamination agent was added.

8a to 8f are graphs showing changes in cesium concentration over time due to the decontamination agent of Example 1. FIG. 8a is a graph showing the change in cesium concentration after 1 minute by the decontamination agent of Example 1, and FIG. 8b is a graph showing the change in cesium concentration after 3 minutes by the decontamination agent of Example 1. FIG. 8c is a graph showing the change in cesium concentration after 10 minutes by the decontamination agent of Example 1, and FIG. 8d shows the change in cesium concentration after 60 minutes by the decontamination agent of Example 1. 8d is a graph showing the change in cesium concentration after 120 minutes due to the decontamination agent of Example 1, and FIG. 8f shows the change in cesium concentration after 1440 minutes due to the decontamination agent of Example 1. It is a graph shown.

With reference to FIGS. 8a to 8f, it can be confirmed that cesium is rapidly removed at a deeper depth than the powdered decontamination agent in the case of the cesium concentration in water, and cesium at the deepest depth after one day has passed. The removal rate reached about 80%. However, the characteristic that cesium relatively near the water surface was hardly removed was observed.

The decontamination agents of Comparative Examples 1 to 5 produced at different compounding ratios from the decontamination agent of Example 1 did not clearly cause a delay in the sedimentation rate or a dispersion phenomenon in the horizontal direction. In the case of some decontamination agents, dispersion did not occur at all until the bottom of the aquarium was reached, and in some decontamination agents, dispersion occurred, but the degree of dispersion was weak.

As described above, after selecting zeolite powder as the basic substance of the cesium decontamination agent in water, chemicals such as sodium hydrogen carbonate and citric acid were added to improve the existing powder type decontamination agent. As a result of adding the improved decontamination agent to the water tank and measuring the turbidity and the concentration of cesium, the sedimentation, horizontal dispersion, and spatial removal rate were all different from those when the existing zeolite powder was added. In the case of the zeolite decontamination agent charged in the powder form, vertical sedimentation was predominant over horizontal dispersion, and the cesium concentration in water also decreased only in the vertical direction in which the zeolite was precipitated. Since the sedimentation was predominant, the powder reached the bottom 3 minutes after the decontamination agent was added, and was distributed parallel to the bottom 10 minutes later.

Of the improved decontamination agents of Example 1 and Comparative Example, the remaining types of decontamination agents except Example 1 did not clearly cause a delay in sedimentation rate or horizontal dispersion. The decontamination agent of Example 1 settled in the vertical direction similar to the powder type decontamination agent, but after the decontamination agent was dispersed in the horizontal direction at about 60 cm below the water surface, it re-precipitated and became a powder type. The dispersion was much wider than that of the decontamination agent. The decrease in cesium concentration in water was slightly different depending on the measurement position, but unlike the powder-type decontamination agent in which the decrease in cesium concentration occurred even near the water surface, the decontamination agent of Example 1 took time. Even after that, cesium near the water surface remained.

In this way, considering the sedimentation, dispersion and cesium removal characteristics for each decontamination agent type, the decontamination agent of Example 1 among the decontamination agents improved with different compounding ratios is distributed in the deep part of the water system. It is judged that it is appropriate to apply it to the application to remove.

From the experimental results, as a radioactive cesium decontamination agent, a decontamination agent containing 30 to 40% by weight of zeolite; 30 to 40% by weight of sodium hydrogen carbonate; and 20 to 40% by weight of citric acid was used as a decontamination agent for radioactive cesium in a deep water system. Determined as an adjustable decontamination agent for.

[Example 2] Production of radioactive cesium decontamination agent (for middle layer)
In the foam decontamination agent, the main additives, sodium hydrogen carbonate, citric acid, and zeolite are mixed at the contents shown in Table 5, and ethanol (C ₂ H ₅ OH) is used to form these. It was used. As the result of the preliminary experiment, the amount of zeolite charged based on 1 ton was set to 50 g and applied in the same manner. Ethanol for mixing and molding zeolite and other accompanying materials is injected inside and outside 20% of the total decontamination agent mass, placed in a production frame and dried in an oven set at 40 ° C for 2 days or more. Manufactured a decontamination agent. As a result of comparing the weights of the finally produced decontamination agents, a mass loss of about 20% inside and outside occurred in the process of production and drying. The final dosage form was to have the form of pellets or tablets.

[Comparative Examples 6 to 10] Production of radioactive cesium decontamination agent (outside the middle layer)
The decontamination agent was produced by the same method as in Example 2, but the decontamination agents of Comparative Examples 6 to 10 were produced according to the composition ratios shown in Table 5 below.

Analysis of dispersion in water and decontamination tendency In order to remove cesium in water, decontamination agents (Example 2, Comparative Examples 6 to 10) produced at different blending ratios were placed in a water tank, and then settled and dispersed. The tendency was observed, and the turbidity and the concentration of cesium according to the position and depth of the decontamination agent of Example 2 having the best dispersion tendency were measured and shown.

9a to 9f are graphs showing changes in turbidity concentration over time due to the decontamination agent of Example 2. FIG. 9a is a graph showing the change in turbidity concentration after 1 minute by the decontamination agent of Example 2, and FIG. 9b shows the change in turbidity concentration after 3 minutes by the decontamination agent of Example 2. 9c is a graph showing the change in turbidity concentration after 10 minutes by the decontamination agent of Example 2, and FIG. 9d is a graph showing the turbidity concentration after 60 minutes by the decontamination agent of Example 2. 9d is a graph showing the change, and FIG. 9d is a graph showing the change in turbidity concentration after 120 minutes by the decontamination agent of Example 2, and FIG. 9f is a graph showing the change in turbidity concentration after 1440 minutes by the decontamination agent of Example 2. It is a graph which showed the turbidity concentration change of.

Referring to FIGS. 9a to 9f, unlike the powder type decontamination agent in which sedimentation occurs only in the vertical direction without horizontal dispersion, the water decontamination agent sediments in the vertical direction and is about 30 cm below the water surface. After rising to the surface of the water again, it seems that it spreads downward, and unlike the powder type decontamination agent that had all sunk to the bottom before 1 hour passed, a small amount of decontamination even after 2 hours passed. It was confirmed that the dye particles were suspended and the sedimentation delay effect occurred. It was also confirmed that the horizontal dispersion effect of the particles was generated in the process of ascending to the water surface again and then settling.

10a to 10f are graphs showing changes in cesium concentration over time due to the decontamination agent of Example 2. FIG. 10a is a graph showing the change in cesium concentration after 1 minute by the decontamination agent of Example 2, and FIG. 10b is a graph showing the change in cesium concentration after 3 minutes by the decontamination agent of Example 2. FIG. 10c is a graph showing the change in cesium concentration after 10 minutes by the decontamination agent of Example 2, and FIG. 10d shows the change in cesium concentration after 60 minutes by the decontamination agent of Example 2. 10d is a graph showing the change in cesium concentration after 120 minutes due to the decontamination agent of Example 2, and FIG. 10f shows the change in cesium concentration after 1440 minutes due to the decontamination agent of Example 2. It is a graph shown.

Referring to FIGS. 10a to 10f, the concentration of cesium decreased rapidly in a wide range, and the cesium removal rate varied depending on the depth, but it was confirmed to be up to 70%, similar to the large horizontal dispersion.

The decontamination agents of Comparative Examples 6 to 10 produced at different compounding ratios from the decontamination agent of Example 2 did not clearly cause a delay in the sedimentation rate or a dispersion phenomenon in the horizontal direction. In the case of some decontamination agents, dispersion did not occur at all until the bottom of the aquarium was reached, and in some decontamination agents, dispersion occurred, but the degree of dispersion was weak.

As described above, after selecting zeolite powder as the basic substance of the cesium decontamination agent in water, chemicals such as sodium hydrogen carbonate and citric acid were added to improve the existing powder type decontamination agent. As a result of adding the improved decontamination agent to the water tank and measuring the turbidity and the concentration of cesium, the sedimentation, horizontal dispersion, and spatial removal rate were all different from those when the existing zeolite powder was added. In the case of the zeolite decontamination agent charged in the powder form, vertical sedimentation was predominant over horizontal dispersion, and the cesium concentration in water also decreased only in the vertical direction in which the zeolite was precipitated. Since the sedimentation was predominant, the powder reached the bottom 3 minutes after the decontamination agent was added, and was distributed parallel to the bottom 10 minutes later.

Of the improved decontamination agents of Example 2 and Comparative Example, the remaining types of decontamination agents except Example 2 did not clearly cause a delay in sedimentation rate or horizontal dispersion. The decontamination agent of Example 2 settled in the vertical direction similar to the powder type decontamination agent, but the settling was delayed while resurfaced from about 30 cm below the water surface to the water surface, and in the process, it was horizontal. It was confirmed that the dispersion phenomenon also occurred in the direction. The concentration of cesium in water decreased rapidly over a wide range, similar to the area where the particles were dispersed, although there were some differences depending on the measurement position.

In this way, considering the sedimentation, dispersion and cesium removal characteristics for each decontamination agent type, among the decontamination agents improved with different compounding ratios, the decontamination agent of Example 2 is distributed in the middle layer of the water system. It is judged that it is appropriate to apply it to the purpose of removal.

From the experimental results, as a radioactive cesium decontamination agent, a decontamination agent containing 40 to 60% by weight of zeolite; 20 to 40% by weight of sodium hydrogen carbonate; and 10 to 20% by weight of citric acid is used for decontaminating radioactive cesium in the middle layer water system. Determined as an adjustable decontamination agent.

[Example 3] Production of dosage form of decontamination agent to which corn starch is added (for middle layer)
In the process of producing the foaming decontamination agent of Example 3, corn starch (corn-starch) was additionally blended to enhance the binding force. When corn starch is additionally included in the decontamination agent, the dosage form of the adsorbent can be adjusted to be constant, and as the strength is increased, it is easier to adjust the depth. When the corn starch is not added, the form of the decontamination agent is the same as that of FIG. 11a, and the form of the decontamination agent obtained by adding the corn starch is the same as that of FIG. 11b. Example 3 was made for the middle layer. The composition ratio of Example 3 is as shown in Table 6.

[Example 4] Production of dosage form of decontamination agent to which corn starch is added (outside the middle layer)
Example 4 is a decontamination agent for use outside the middle layer, which is produced by changing the composition ratio in the process of manufacturing the foam type decontamination agent of Example 3. The composition ratio of Example 4 is as shown in Table 6.

[Comparative Examples 11 to 13] Production of Dosage Form of Decontamination Agent to which Corn Starch is Added Comparative Examples 11 to 13 are decontamination agents produced by changing the composition ratio in the process of producing a foaming decontamination agent. The composition ratios of Comparative Examples 11 to 13 are shown in Table 6.

Additional Analysis of Dispersion in Water In order to remove cesium in water, decontamination agents (Example 3, Example 4, Comparative Examples 11 to 13) produced at different compounding ratios are shown in FIGS. 12 to 17. A similar 40 L (length 30 cm, width 30 cm, depth 50 cm) water tank was filled with water having a water temperature of 20 ° C. to a depth of 45 cm, and then an adsorbent was dropped at 5 cm above the water surface to observe the tendency of sedimentation and dispersion. As shown in FIGS. 11a and 11b, the dosage form of the adsorbent was produced in the form of a cylinder having a diameter of 3 cm, a height of 1 cm, and a mass of about 10 g.

12a to 12d show the time-dependent dispersion pattern of the decontamination agent of Example 3. FIG. 12a shows the dispersion mode 2 seconds after the administration of the decontamination agent of Example 3. Immediately after being dropped, the decontamination agent of Example 3 sinks to 10 cm below the surface of the water, resurfaces, and disperses on the surface of the water for 3 seconds. FIG. 12b shows the dispersion mode 8 seconds after the administration of the decontamination agent of Example 3. The decontamination agent of Example 3 sinks to the bottom of the aquarium 8 seconds after the administration. FIG. 12c shows the dispersion mode 20 seconds after the administration of the decontamination agent. The decontamination agent of Example 3, which was strongly dispersed only in the vertical direction, resurfaces on the water surface 20 seconds after the administration. FIG. 12d shows the dispersion mode 40 seconds after the administration of the decontamination agent of Example 3. The decontamination agent of Example 3 continues to be dispersed, and after 40 seconds, it is completely dispersed in the entire water tank.

13a to 13d show the time-dependent dispersion pattern of the decontamination agent of Example 4. FIG. 13a shows the dispersion mode 2 seconds after the administration of the decontamination agent of Example 4. Immediately after the decontamination agent of Example 4, the decontamination agent sinks to 5 cm below the water surface and resurfaces, but immediately sinks. FIG. 13b shows the dispersion mode 5 seconds after the administration of the decontamination agent of Example 4. The decontamination agent of Example 4 reaches the bottom of the aquarium 5 seconds after administration. FIG. 13c shows the dispersion mode 20 seconds after the administration of the decontamination agent of Example 4. The decontamination agent of Example 4, which was strongly dispersed in the vertical direction and weakly dispersed in the horizontal direction and showed the dispersion behavior of the I form, resurfaces on the water surface 30 seconds after the administration. FIG. 13d shows the dispersion mode 40 seconds after the administration of the decontamination agent of Example 4. The decontamination agent of Example 4 continues to be dispersed, and after 35 seconds, it is completely dispersed in the entire water tank.

14a to 14c show the time-dependent dispersion pattern of the decontamination agent of Comparative Example 11. FIG. 14a shows the dispersion mode 4 seconds after the administration of the decontamination agent. The decontamination agent of Comparative Example 11 reaches the bottom of the water tank 4 seconds after being dropped. FIG. 14b shows the dispersion mode 20 seconds after the administration of the decontamination agent of Comparative Example 11. In the decontamination agent of Comparative Example 11, after reaching the bottom of the water tank, the bond of the decontamination agent is broken and the particles are dispersed in the vertical direction. FIG. 14c shows the dispersion mode 60 seconds after the administration of the decontamination agent of Comparative Example 11. The particles dispersed by the decontaminating agent of Comparative Example 11 and rising near the water surface settle again, and after 60 seconds have passed, are uniformly dispersed in the entire water tank.

15a to 15c show the time-dependent dispersion pattern of the decontamination agent of Comparative Example 12. FIG. 15a shows the dispersion mode 2 seconds after the administration of the decontamination agent of Comparative Example 12. Immediately after being dropped, the decontamination agent of Comparative Example 12 sinks to 10 cm below the water surface, resurfaces, and disperses on the water surface for 1 second. FIG. 15b shows the dispersion mode 5 seconds after the administration of the decontamination agent of Comparative Example 12. The decontamination agent of Comparative Example 12 sinks to the bottom of the aquarium 5 seconds after the administration. FIG. 15c shows the dispersion mode 70 seconds after the administration of the decontamination agent of Comparative Example 12. The decontamination agent of Comparative Example 12 is dispersed in the vertical direction, and after 70 seconds have passed, it is completely dispersed.

16a to 16d show the time-dependent dispersion pattern of the decontamination agent of Comparative Example 13. FIG. 16a shows the dispersion mode 4 seconds after the administration of the decontamination agent. Immediately after being dropped, the decontamination agent of Comparative Example 13 sinks to 10 cm below the water surface, resurfaces, and disperses on the water surface for 3 seconds. FIG. 16b shows the dispersion mode 8 seconds after the administration of the decontamination agent of Comparative Example 13. Eight seconds after administration, the decontamination agent of Comparative Example 13 sinks to the bottom of the aquarium and then disperses only in the vertical direction. FIG. 16c shows the dispersion mode 20 seconds after the administration of the decontamination agent. The decontamination agent of Comparative Example 13 resurfaces on the water surface 20 seconds after its administration. FIG. 16d shows the dispersion mode 60 seconds after the administration of the decontamination agent of Comparative Example 13. The decontamination agent of Comparative Example 13 continues to be dispersed, and after 60 seconds, it is completely dispersed in the entire water tank.

Table 7 shows the evaluation of the dispersion behaviors of Examples 3, 4 and 11 to 13. The 45 cm depth of the water tank was divided into three equal parts by 15 cm from the top and divided into upper, middle and lower regions, and the regions were described in the order in which the decontaminating agent was horizontally dispersed to evaluate the dispersion behavior.

The dispersion rate was evaluated by recording the time required for the adsorbent to completely spread over the entire water tank and complete the dispersion. As a result of the experiment, considering the dispersion behavior and the dispersion rate, it was judged that it is most suitable to carry out the decontamination agent for the middle layer as in Example 3 and the decontamination agent for deep layers as in Example 4.

Additional analysis of water dispersion by temperature Additional experiments were performed to investigate the dispersion performance by temperature and mass of adsorbent dosage form. 17a and 17b show the dispersion mode of the decontaminating agent depending on the temperature and the mass of the dosage form of the adsorbent.

FIG. 17a shows after dropping a decontamination agent having the same compounding ratio as in Example 3 and produced in a dosage form of 10 g into two water tanks having different temperatures of 0 ° C (left) and 20 ° C (right). , 15 seconds have passed. As a result of evaluating the dispersion performance of the decontamination agent in a low temperature environment of 0 ° C to 3 ° C, the decontamination agent produced to 10 g stays only on the water surface regardless of the compounding ratio, and is vertical without horizontal dispersion. It disperses only in the direction, and the dispersion rate is significantly slower than the dispersion rate at room temperature.

FIG. 17b shows 15 seconds after dropping the decontamination agent produced in 12 g having the same compounding ratio as in Example 4 into two water tanks having different temperatures of 0 ° C (left) and 20 ° C (right). It shows how the time has passed. As a result of evaluating the dispersion performance of the decontamination agent in a low temperature environment of 0 ° C to 3 ° C, the weight of the decontamination agent's dosage form increased in the decontamination agent produced to 12 g, and the decontamination agent bottomed out in water. When it reaches, it is possible to overcome the decrease in dispersion of the decontamination agent in a low temperature environment. That is, the dispersion rate of the decontamination agent is slightly slower than that at room temperature of 20 ° C. Shows excellent dispersion behavior.

This technology is related to decontamination technology for pollutants in water, and in particular, is a technology related to decontamination agents and decontamination methods that can efficiently decontaminate radioactive cesium existing in water at various water depths. ..

Claims (24)

A decontamination agent for removing radioactive substances contained in contaminated water.
Zeolites; sodium hydrogen carbonate; decontamination agents for radioactive contaminants including citric acid. The decontamination agent is 30 to 60% by weight of zeolite;
The decontamination agent according to claim 1, which is 20 to 40% by weight of sodium hydrogen carbonate; and 10 to 40% by weight of citric acid. The decontamination agent is zeolite 40-60% by weight; sodium hydrogencarbonate 20-40% by weight; and citric acid 10-20% by weight.
The decontamination agent according to claim 1, wherein the decontamination agent is for removing radioactive substances contained in a middle layer water system. The decontamination agent is zeolite 30-40% by weight; sodium hydrogencarbonate 30-40% by weight; and citric acid 20-40% by weight.
The decontamination agent according to claim 1, wherein the decontamination agent is for removing radioactive substances contained in a deep water system. The decontamination agent according to claim 1, wherein the decontamination agent further contains corn starch. The decontamination agent according to claim 2, wherein the decontamination agent is 5 to 20% by weight of corn starch. The decontamination agent according to claim 6, wherein the decontamination agent has a weight ratio of zeolite, sodium hydrogen carbonate, citric acid and corn starch of 2: 1 to 2: 0.5 to 1: 0.25 to 1. .. The decontamination agent has a weight ratio of zeolite, sodium hydrogen carbonate, citric acid and corn starch of 2: 1: 0.5: 0.5, and the decontamination agent contains radioactive substances contained in the middle layer water system. The decontamination agent according to claim 7, which is intended for removal. The decontamination agent has a weight ratio of zeolite, sodium hydrogen carbonate, citric acid and corn starch of 2: 1: 0.5: 0.25, and the decontamination agent contains radioactive substances contained in a deep water system. The decontamination agent according to claim 7, which is intended for removal. The decontamination agent according to claim 1, wherein the zeolite is 50 to 60% by weight of heulandite and 40 to 50% by weight of heulandite. The zeolite has a specific surface area of 50 to 70 m ² / g, an average void volume of 0.1 to 0.15 ml / g, an average void size of 5 to 15 nm, and a cation exchange capacity. The decontamination agent according to claim 1, wherein the amount is 60 to 120 meq / 100 g. The decontamination agent according to claim 1, wherein the radioactive substance is selected from the group consisting of iodine, cesium, cerium, rhodium, cobalt, strontium, radium, uranium, and plutonium. To remove radioactive substances contained in contaminated water
A method for producing a decontaminating agent for radioactive contaminants by mixing zeolite; sodium hydrogen carbonate; and citric acid. The decontamination agent is 30 to 60% by weight of zeolite;
The method for producing a decontaminating agent for a radioactive contaminant according to claim 13, which is 20 to 40% by weight of sodium hydrogen carbonate; and 10 to 40% by weight of citric acid. The decontamination agent is zeolite 40-60% by weight; sodium hydrogencarbonate 20-40% by weight; and citric acid 10-20% by weight.
The method for producing a decontamination agent for a radioactive contaminant according to claim 13, wherein the decontamination agent is for removing a radioactive substance contained in a middle layer water system. The decontamination agent is zeolite 30-40% by weight; sodium hydrogencarbonate 30-40% by weight; and citric acid 20-40% by weight.
The method for producing a decontamination agent for a radioactive contaminant according to claim 13, wherein the decontamination agent is for removing a radioactive substance contained in a deep water system. The method for producing a decontamination agent for a radioactive contaminant according to claim 13, wherein the decontamination agent further comprises corn starch. The method for producing a decontaminating agent for a radioactive contaminant according to claim 14, wherein the decontaminating agent is 5 to 20% by weight of corn starch. The radioactive contaminant according to claim 18, wherein the decontaminating agent has a weight ratio of zeolite, sodium hydrogen carbonate, citric acid and corn starch of 2: 1 to 2: 0.5 to 1: 0.25 to 1. How to make a decontamination agent for. The decontamination agent contained zeolite, sodium hydrogen carbonate, citric acid and corn starch in a weight ratio of 2: 1: 0.5: 0.5, and the decontamination agent was contained in the middle layer water system. The method for producing a decontaminating agent for a radioactive contaminant according to claim 19, which is for removing radioactive substances. The decontamination agent contained zeolite, sodium hydrogen carbonate, citric acid and corn starch in a weight ratio of 2: 1: 0.5: 0.25, and the decontamination agent was contained in a deep water system. The method for producing a decontaminating agent for a radioactive contaminant according to claim 19, which is for removing radioactive substances. The method for producing a decontaminating agent for a radioactive contaminant according to claim 13, wherein the zeolite is 50 to 60% by weight of heulandite and 40 to 50% by weight of heulandite. The zeolite has a specific surface area of 50 to 70 m ² / g, an average void volume of 0.1 to 0.15 ml / g, an average void size of 5 to 15 nm, and a cation exchange capacity. The decontamination agent according to claim 13, wherein the amount is 60 to 120 meq / 100 g. The decontamination agent according to claim 13, wherein the radioactive substance is selected from the group consisting of iodine, cesium, cerium, rhodium, cobalt, strontium, radium, uranium, and plutonium.

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