Preparation method of nano-bimetallic composite remover for the removal of cesium-containing wastewater

Abstract

A preparation method for removing caesium-containing wastewater nano-bimetallic composite remover, the nano-bimetallic composite remover made has excellent performance, is a composite bimetallic material with high selectivity, can be effectively used for the removal of cesium in wastewater, and reduce the content of cesium in wastewater, and can adjust the composition ratio of nano-scale bimetallic powder and alkaline activator according to demand, so as to obtain good performance, its chemical stability and mechanical strength are good, and the process of adsorbing cesium ions is simple. It has obvious selectivity and advantages for the extraction of cesium ions from seawater, which can improve the cesium removal efficiency of pollutants in polluted wastewater and meet the discharge standards.

Description

[Technical Field]

[0001] This invention relates to a method for preparing a nano-bimetallic composite removal agent for removing cesium-containing wastewater, and more particularly to a nano-bimetallic composite removal agent composed of nano-scale bimetallic powder prepared by co-precipitation and particulate material formed by polycondensation synthesis. In particular, it refers to a material that can adsorb cesium ions, has significant advantages in extracting cesium ions from seawater, and thus improves the removal efficiency of pollutants in wastewater. [Previous Technology]

[0002] Currently, due to the subsequent processing procedures following nuclear power generation or use, it is necessary to develop key technologies for nuclear power plant decommissioning and nuclear waste disposal, and establish independent nuclear back-end industry technology capabilities. Furthermore, the Fukushima incident in Japan resulted in the leakage of a large amount of radioactive waste, including significant amounts of radioactive nuclides such as cesium (Cs) and strontium (Sr), with the leakage and contamination of cesium-137 (Cs-137) being particularly severe. Cs-137 has a relatively long half-life (30 years), emits high-energy gamma rays, and cesium ions have higher water solubility and mobility compared to other radioactive nuclides, making it one of the main sources of radioactivity in major nuclear accidents.

[0003] Nuclear accidents usually have a significant impact on surrounding water bodies. For example, after the Fukushima nuclear accident, thousands of tons of radioactive cesium wastewater leaked into the Pacific Ocean, causing serious pollution to the environment and water bodies and threatening the environment and human health and safety.

[0004] Therefore, there is an urgent need to develop adsorption materials that can be fast, efficient, highly selective and have a large adsorption capacity to solve the problem of environmental water pollution caused by radioactive cesium ions in nuclear accidents.

[0005] Therefore, the effective removal of radioactive ions is of considerable importance. The removal of radioactive cesium ions from environmental water bodies mainly employs adsorption (ion exchange), chemical precipitation, evaporation and concentration, solvent extraction, and membrane treatment. The removal agents used must be materials with selectivity and binding affinity to radioactive cesium ions. Current research focuses on materials such as zeolite, Prussian blue, silica-polymer-calixcrown hybrid materials, ammonium molybdophosphate, and crown ethers. However, an ideal Cs-137 removal agent must provide excellent and selective binding to Cs-137, because the concentration of Cs-137 in the environment is usually significantly lower than the concentration of competing cations (such as potassium (K+), sodium (Na+), calcium (Ca2+), and magnesium (Mg2+) ions).

[0006] The treatment and disposal of radioactive wastewater generally involves diluting and diffusing low-level radioactive wastewater before discharging it into water bodies that meets discharge standards; or concentrating and solidifying the radioactive wastewater to isolate it from the human living environment for a long period, allowing it to decay naturally. The second principle has a wider applicability, applicable to high, medium, and low-level radioactive wastewater. The treatment objective for radioactive wastewater is judged by achieving higher decontamination factor (DF) and concentration factor (CF). DF refers to the ratio of radioactive concentration to mass concentration in the influent and effluent; CF refers to the ratio of the original volume of the influent radioactive wastewater to the volume of the concentrated radioactive products after treatment. Higher DF and CF indicate better radioactive removal from the water sample and a smaller volume of concentrated waste, thus facilitating the solidification and isolation of concentrated radioactive waste.

[0007] Currently, physical, chemical, biological, and membrane separation technologies have been developed for the treatment of radioactive wastewater. The characteristics of radioactive wastewater treatment technologies are as follows: (I) Chemical co-precipitation involves adding chemicals to the wastewater to cause coagulation and sedimentation, thereby removing nuclei and fine suspended particles from the wastewater. Nuclei are concentrated in sludge and then separated by physical methods (such as filtration). This method is generally suitable for treating alkaline, low-activity, and high-concentration salt wastewater. The procedure is simple and the setup and operation costs are low. However, it is difficult to separate precipitated colloids and other substances, and organic matter is easily decomposed. The selective adsorption and competition with other ions leads to low adsorption and separation efficiency of cesium, making the precipitated adsorption products more difficult to treat. (II) Ion exchange resins are suitable for treating wastewater with extremely low concentrations, such as removal agents. (III) Evaporation concentration has a good effect on removing pollutants from high-concentration inorganic wastewater. It has the highest pollutant removal factor among current wastewater treatment methods. The distillate after treatment can be recycled and reused, and the concentrated wastewater will be further solidified. (iv) Thin film treatment includes reverse osmosis and thin film distillation, which have the advantages of no temperature change and phase change and low energy consumption. However, the concentrate must be further concentrated by evaporation.

[0008] Generally, radioactive nuclides that may be present in nuclear wastewater mainly include Cs-134, Cs-137, iodine-125 (I-125), I-129, I-131, radium-226 (Ra-226), and Ra-228. Cs-137, I-129, and I-131 are the most common radioactive nuclides released during nuclear leaks. Compared to other radioactive nuclides, these are more easily absorbed by the human body and are extremely harmful. Therefore, removing radioactive cesium is a key element in the treatment of radioactive wastewater.

[0009] Currently, the main methods for removing cesium from water are ion exchange resin method, absorption method, and adsorption method. Among them, the ion exchange resin method is suitable for capturing cesium from low-concentration wastewater, and the removal agent has good selectivity. However, the removal agent is easily interfered with by other impurities in the wastewater, and the operation process is relatively cumbersome.

[0010] Adsorption methods, characterized by simple technology, large adsorption capacity, and high selectivity, have become the most competitive method. Adsorption (ion exchange) uses a removal agent to adsorb radioactive cesium nuclei from a water sample onto its surface. Through ion exchange with the material, the radioactive nuclei are removed and effectively immobilized. Because it introduces fewer other chemical substances into the water sample, it is a simpler and less polluting method, thus having wide applications. However, adsorption methods are easily affected by interference from other ions in the water, resulting in problems such as low adsorption capacity, frequent regeneration, and high treatment costs. Therefore, there is a need to develop more economical, easily prepared, conveniently stored, highly efficient, and highly selective adsorption materials. Research on removal agent technologies mainly includes activated carbon adsorption, microporous exchange resin adsorption, bimetallic exchange or bimetallic impregnated zeolite, silica gel, or alumina adsorption.

[0011] These materials each have different advantages and disadvantages. Most of them have irregular shapes or too fine particles, resulting in poor internal mass transfer conditions and mechanical strength, making them unsuitable for fixed-bed operation. To improve the adsorption and removal efficiency of inorganic ion removers, they are often loaded onto porous material supports to form composite materials. Commonly used supports typically have high surface area and are porous, including activated carbon (AC), γ-alumina (γ-Al₂O₃), silicon dioxide (SiO₂), cerium dioxide (CeO₂), magnesium oxide (MgO), titanium dioxide (TiO₂), silica, MCM-41 composed of silicates and aluminates, ion exchange resins, polyvinyl alcohol, polyacrylonitrile, and zeolites, etc. Different materials and morphologies will also affect their metal loading and adsorption / desorption capabilities. However, previously synthesized cesium selective composite materials have defects such as low inorganic ion exchanger loading or irregular shapes. Therefore, it is necessary to develop cesium selective removal agents with the same particle size and shape, and their preparation methods, for application in fixed adsorption removal beds to remove pollutants from wastewater.

[0012] Recent developments and applications of ferrocyanide exchange materials include adsorbing potassium nickel ferrocyanide onto zeolite or loading copper ferrocyanide onto polyurethane to prepare composite ion exchanger particles, thereby improving removal efficiency. Another method involves preparing spherical composite exchange materials using the sol-gel method. This method can modify the properties of materials that are difficult to shape by combining them into gel spheres. This method can produce spherical particles with adjustable particle size, resulting in uniform particles with good mechanical strength, large porosity, and specific surface area. However, a drawback is the significant shrinkage of the gel spheres during drying, and some composite gel spheres are prone to cracking and fragmentation during drying.

[0013] Currently, there are relevant patents that disclose the preparation method of carboxymethyl cellulose and Prussian blue composite gel microsphere adsorbent materials. The preparation procedure is as follows: carboxymethyl cellulose and Prussian blue are dissolved and mixed in water to form a composite sol, then the composite sol is injected into a metal salt solution, and a crosslinking agent is added. The mixture is stirred and shaped to obtain microspheres, which are then rinsed with ultrapure water, filtered and dried to prepare composite gel microsphere adsorbent materials.

[0014] Another related patent uses a method for preparing three-dimensional ordered porous carbon composite Prussian blue. The process is as follows: porous carbon material prepared by carbonization technology is mixed with 30 mM ferric chloride (FeCl3), then 30 mM potassium ferricyanide (K3Fe(CN)6) and concentrated hydrochloric acid are added, and the mixture is heated and refluxed at 80°C for 12 hours to obtain a blue product. The product is then washed with ultrapure water until the pH value is 7, and then dried in an oven at 75°C for 3 hours to obtain the Prussian blue / three-dimensional ordered porous carbon composite material.

[0015] The technology for preparing Prussian blue composite materials is a traditional synthesis method. The reaction process is relatively complicated. It requires the addition of a variety of chemical reactants and the use of a large number of chemical reagents, which increases the cost of the material. At the same time, the residues may remain in the product, affecting its adsorption performance and efficiency, and posing a threat to the environment.

[0016] Given the high mobility of cesium nuclei following the Fukushima nuclear disaster in Japan, making it one of the most difficult radioactive nuclei to handle, research on the removal of radioactive cesium from water bodies in China is relatively scarce, especially regarding emergency technologies for treating radioactive cesium nuclei in water, with limited achievements. Therefore, to prepare for potential large-scale radioactive cesium contamination of water bodies in the future, it is essential to establish relevant treatment technologies in advance. Thus, developing a new technology that can effectively solve the problem of radioactive cesium contamination in water bodies and overcome the shortcomings of existing technologies is crucial. [Summary of the Invention]

[0017] The main objective of this invention is to overcome the above-mentioned problems encountered in the prior art and to provide a nano-bimetallic composite remover that uses nano-bimetallic powder to adsorb cesium ions, while increasing the cesium ion adsorption and exchange removal effect and increasing the adsorption sites. It can also be used as a remover in a wastewater treatment system and improve the removal rate of radioactive nuclides. This method is for preparing a nano-bimetallic composite remover for removing cesium-containing wastewater.

[0018] Another objective of the present invention is to provide a method for preparing a nano-bimetallic composite removal agent for removing cesium from cesium-containing wastewater, radioactive wastewater, or routine wastewater from nuclear power plants and nuclear facilities, thereby achieving discharge standards and producing uncontaminated water samples.

[0019] Another objective of the present invention is to provide a method for preparing a nano-bimetallic composite removal agent for removing cesium-containing wastewater by means of a nano-bimetallic composite removal agent prepared by co-precipitation method, which has good adsorption performance for cesium ions in water.

[0020] To achieve the above objectives, the present invention relates to a method for preparing a nano-bimetallic composite removal agent for removing cesium-containing wastewater, comprising at least the following steps: Step 1: Dissolving two transition metal chloride salts with concentrations between 0.1 and 2.0 M as co-precipitation substrates in water, dissolving at a low temperature of 25-65°C and maintaining a constant temperature to form a bimetallic solution; and dissolving a transition metal chloride salt with a concentration between 0.1 and 1.5 M in water. The ferrocyanide between M and M dissolves in water to form a ferrocyanide solution. This ferrocyanide solution is slowly added to the bimetallic solution, with a ratio of 0.5 to 3.5. After stirring for 4 to 16 hours, the precipitate is filtered and washed with water to remove any unreacted reagents. After drying at a low temperature of 85 to 125°C, the powder is ground to prepare a nano-sized bimetallic powder. Step 2: The aluminosilicate material is calcined and activated at a high temperature of 600 to 900°C to achieve an amorphous structure. The nano-sized bimetallic powder is mixed with the calcined and activated aluminosilicate material at a ratio of 1 to 5:1. Then, 1 to 5 M of alkaline activator are added and stirred until homogeneous to form a paste-like polymerization mixture. Step 3: The paste-like polymerization mixture is coated onto a template with an array of 1 to 2 mm pores and polymerized and cured at room temperature for 1 to 3 hours. After curing and demolding, the particle size of 1 to 2 mm is obtained. mm-sized bimetallic composite remover.

[0021] In the above embodiments of the present invention, the average particle size of the nano-scale bimetallic powder is 40±20% nm.

[0022] In the above embodiments of the present invention, the bimetallic solution is an aqueous solution containing at least one bimetallic compound selected from the group consisting of bimetallic nitrate, bimetallic sulfate, bimetallic acetate, and bimetallic chloride.

[0023] In the above embodiments of the present invention, the transition metal chloride salt is selected from at least two soluble salts in the group consisting of nickel chloride, cobalt chloride, ferric chloride and potassium chloride.

[0024] In the above embodiments of the present invention, the ferrocyanide is selected from at least one of the group consisting of potassium ferrocyanide, sodium ferrocyanide, copper ferrocyanide, potassium titanium ferrocyanide and nickel ferrocyanide.

[0025] In the above embodiments of the present invention, the nano-bimetallic composite remover can adjust the composition ratio of the nano-bimetallic powder and the alkaline activator as needed, and adjust the polymerization curing and granulation ratio.

[0026] In the above embodiments of the present invention, the alkaline activator is sodium metasilicate solution and the silica aluminate material is metakaolin.

[0027] To achieve the above objectives, the present invention is a nano bimetallic composite removal agent, which is prepared by the above preparation method. Its cesium removal rate in water is greater than 98%, and its BET (Brunauer-Emmett-Teller) specific surface area is at least 35 m2 / g, and it has a mechanical strength of 0.71 kgf / mm or higher.

Implementation Method

[0028] Please refer to Figures 1-3, which are respectively schematic diagrams of the manufacturing process of the nano-bimetallic composite remover of the present invention, schematic diagrams of the mechanical strength of the nano-bimetallic composite remover of the present invention, and test diagrams of the continuous cesium removal adsorption efficiency of the nano-bimetallic composite remover of the present invention. As shown in the figures: The present invention is a method for preparing a nano-bimetallic composite remover for removing cesium-containing wastewater. The nano-bimetallic composite remover is a nano-composite functional cesium removal agent material composed of bimetallic composite materials, which has the effect of adsorbing cesium ions. It can increase the cesium ion adsorption capacity and increase the adsorption removal effect. It can be used as a remover in wastewater treatment systems and improve the removal rate of radioactive nuclides. It is suitable for removing cesium from cesium-containing polluted wastewater, radioactive waste liquid, or routine wastewater from nuclear power plants and nuclear facilities to meet discharge standards and for use in pollution-free water samples. The proposed nano-bimetallic composite remover contains a bimetallic composite material with high selectivity, high specific surface area, and high adsorption capacity, which increases cesium adsorption or ion exchange capacity, and a polymeric blending liquid added to the bimetallic composite material to solidify it and increase its applicability. It can effectively adsorb cesium in water and solve the problem of reducing radioactive pollutants in wastewater discharge. Furthermore, the composition ratio of the bimetallic composite material and the polymeric blending liquid can be adjusted according to needs.

[0029] The bimetallic composite material mentioned above is composed of nano-scale bimetallic powder; while the polymerizing liquid is composed of aluminosilicate material and alkaline activator, thereby forming a polymeric network structure of the nano-bimetallic composite remover. The ratio of the bimetallic composite material to the polymerizing liquid can be adjusted according to the needs to achieve various ratios of adsorption, exchange and dispersion. In this embodiment, 2 M has the best effect.

[0030] The preparation method of the above-mentioned nano-bimetallic composite remover includes at least the following steps: Step s11: Take two 1.6 M transition metal chloride salts as the starting co-precipitation substrates, dissolve them sequentially in 1 liter of deionized water, dissolve them at a low temperature of 25~65°C and maintain a constant temperature to form a bimetallic solution. Take 1 M ferrocyanide and completely dissolve it in 1 liter of deionized water to form a ferrocyanide solution. Slowly and uniformly add the ferrocyanide solution to the bimetallic solution for reaction. The ratio of the ferrocyanide solution to the bimetallic solution is 0.5~3.5. After stirring for 4~16 hours, filter and wash the precipitate with water to remove the residual unreacted reagents. After drying at a low temperature of 85~125°C, grind it to prepare a nano-scale bimetallic powder. Step s12: The aluminosilicate material is calcined and activated at a high temperature of 600~900°C to achieve an amorphous structure with thermodynamic metastable properties, exhibiting high reactivity under alkaline conditions. This nano-scale bimetallic powder is mixed with the calcined and activated aluminosilicate material at a ratio of 1~5:1, and then 1~5 M of alkaline activator is added and stirred until homogeneous, forming a paste-like polymerization mixture. Step s13: This paste-like polymerization mixture is coated onto a template with an array of 1~2 mm pores. Depending on the temperature and humidity, the polymerization and curing time at room temperature is 1~3 hours. After curing and demolding, a high-adsorption-capacity nano-bimetallic composite remover (NCFC) with a particle size of 1~2 mm is completed.

[0031] The above describes the nano-bimetallic composite removal agent obtained by the present invention through a simple co-precipitation method, which is applicable to the adsorption and removal of cesium ions from cesium-containing radioactive wastewater. Thus, the process disclosed above constitutes a novel method for preparing a nano-bimetallic composite removal agent for removing cesium-containing wastewater.

[0032] In one preferred embodiment of the present invention, the nano-bimetallic composite remover is a bimetallic composite remover material with good selectivity, adsorption, ion exchange capacity, high adsorption capacity, and high specific surface area. As shown in Table 1, the specific surface area of ​​the granulated BET (Brunauer-Emmett-Teller) is at least 35 m² / g. Table 1 Remover Cs treat (commercial) This invention (NCFC) BET(m2 / g) 4.74 35.8 Adsorption capacity (meq / g) 0.39 0.52 Cs ion removal rate (%) in seawater 99 99.2

[0033] In one preferred embodiment of the present invention, the modified and activated silicate material has an amorphous crystal structure, exhibiting thermodynamic metastable behavior, and its reactivity in alkaline solutions is enhanced. This allows the surface of the remover of the present invention to effectively contact the adsorbate, and gives the resulting molded product higher adsorption and exchange characteristics, thereby improving its removal rate.

[0034] In one preferred embodiment of the present invention, the average particle size of the nano-scale bimetallic powder is 40 nm.

[0035] In one preferred embodiment of the present invention, the bimetallic solution is an aqueous solution containing at least one bimetallic compound selected from the group consisting of bimetallic nitrate, bimetallic sulfate, bimetallic acetate, and bimetallic chloride.

[0036] In one preferred embodiment of the present invention, the transition metal chloride salt is selected from at least two soluble salts in the group consisting of nickel chloride, cobalt chloride, ferric chloride and potassium chloride.

[0037] In one preferred embodiment of the present invention, the ferrocyanide is selected from at least one of the group consisting of potassium ferrocyanide, sodium ferrocyanide, copper ferrocyanide, potassium titanium ferrocyanide and nickel ferrocyanide.

[0038] In one preferred embodiment of the present invention, the nano-bimetallic composite remover can adjust the composition ratio of the nano-bimetallic powder and the alkaline activator as needed, and adjust the polymerization curing and granulation ratio.

[0039] The following embodiments are only examples to illustrate the details and connotation of the present invention, and are not intended to limit the scope of the patent application of the present invention.

[0040] A preferred embodiment of the nano-bimetallic composite remover of the present invention is to use a remover composed of nano-grade bimetallic powder synthesized by precipitation method as an adsorbent material for adsorbing and removing cesium-containing radioactive waste liquid. The specific implementation steps are as follows: Step 1: Dissolve 100 g of nickel chloride and 60 g of cobalt chloride in one liter of deionized water in sequence, dissolve at 45°C to form a bimetallic solution and maintain a constant temperature. Separately, dissolve 110 g of potassium ferrocyanide completely in one liter of deionized water, slowly and evenly add it to the above bimetallic solution, stir for 12 hours, filter and wash the precipitate with water to remove residual unreacted reagents, and dry at a low temperature of 95°C and grind to prepare a nano-grade bimetallic powder. Step 2: Calcine and activate metakaolin at a high temperature of 700°C. Mix the nano-grade bimetallic powder and the metakaolin in a 1:2 ratio, and then add 1.1 M sodium metasilicate solution and stir to mix evenly to form a paste-like polymerized liquid. Step 3: Apply the paste-like polymerizing liquid to a template with an array of 2 mm holes, polymerize and cure at room temperature for 3 hours, and after curing and demolding, a high adsorption capacity nano-bimetallic composite remover with a particle size of 1~2 mm is completed.

[0041] The present invention uses the nano-bimetallic composite remover prepared by the above co-precipitation method to test the mechanical strength, adsorption efficiency, and decontamination factor of the remover. Wherein:

[0042] The mechanical properties of the nano-bimetallic composite remover and a commercial remover were tested in this invention, as shown in Figure 2 and Table 2. Figure 2(a) shows the mechanical strength value of the commercial remover (Cs treat), and Figure 2(b) shows the mechanical strength value of the nano-bimetallic composite remover of this invention. The results show that the mechanical strength of the nano-bimetallic composite remover proposed in this invention can reach above 0.71 kgf / mm, and the average strength is 0.45 kgf / mm, indicating that the nano-bimetallic composite remover proposed in this invention has better mechanical properties than the commercial remover. Table 2 Remover Cs treat (commercial) This invention (NCFC) Average crushing strength - kgf 0.22 0.45

[0043] The concentration of cesium-containing wastewater in general discharges is approximately 10.0 ppm, calculated by radioactivity conversion. In this invention, cesium nitrate dissolved in deionized water is used as simulated radioactive raw water. At a temperature of 25°C, the initial concentration of cesium in the simulated solution is prepared to be 12.0 ppm. In addition, for the decontamination factor efficiency test, 4 liters of radioactive cesium-137 (Cs-137) solution (activity 80000 Bq / L) prepared by the National Atomic Energy Agency are used to test the decontamination factor.

[0044] [Test Procedure for Adsorption Performance of Removal Agent] Take 20.0 mL sample bottles, add 0.2 g of nano bimetallic composite removal agent and 10.0 mL of simulated cesium solution to each bottle, mix and ultrasonically shake for 12 hours, then let stand for 2 hours to allow activated carbon to precipitate. Extract the supernatant from the sample bottle, filter it through a 0.45 μm syringe filter, and then use an atomic absorption spectrometer (AA) to determine the cesium ion concentration in the filtrate. The experiment is repeated three times and the average value is taken. The cesium ion concentration is detected using AA, and the standard solution for cesium ions is prepared using deionized water.

[0045] [Determination Procedure for Decontamination Factors] A column with a diameter of 1.1 cm and a filling height of 21.1 cm with granular nano-bimetallic composite decontaminant was used. The fixed filling amount of the decontaminant was 20 cm³. A 35-hour continuous adsorption and decontamination test was conducted using a radioactive Cs-137 solution (activity 80000 Bq / L) and a liquid hourly space velocity (LHSV) of 8.75 h⁻¹. The activity after adsorption was analyzed.

[0046] The decontamination factor (DF) is calculated as follows: Decontamination factor (DF) = initial activity / final activity.

[0047] This invention uses a nano-bimetallic composite remover packed in a laboratory-grade column for continuous adsorption testing. The filler volume is fixed at 20 cm³, and cesium nitrate solid dissolved in deionized water is used as simulated radioactive raw water. At room temperature (25°C), the initial concentration of cesium ions in the simulated wastewater solution is 12.85 ppm, as measured by AA. As shown in Figure 3, this invention uses a nano-bimetallic composite remover to conduct continuous cesium removal adsorption efficiency testing. At a fixed flow rate of approximately 4.2 L / d (LHSV = 8.75 h⁻¹), the continuous cesium removal efficiency remains >99%.

[0048] The emission limit for Cs-137 is 0.0802 Bq / mL. Table 3 below shows the decontamination factor test results of the nano-bimetallic composite remover. After treatment with the bimetallic nano-bimetallic composite remover, the residual viability was 0.061 Bq / L, and the calculated decontamination factor was 1311.5. The decontamination factor after 35 hours of continuous treatment meets the emission standard of 1311.5. Table 3 Cesium removal agent Decontamination time Survival DF This invention (NCFC) 35 hr 0.061 1311.5 CsT (Commercial) 35 hr 0.062 1290.3

[0049] The nano-bimetallic composite remover produced by the present invention has the effect of removing cesium from adsorbed wastewater after the above-mentioned actual test, which verifies that the nano-bimetallic composite remover of the present invention is suitable for removing cesium in water bodies under normal operation and accident conditions of nuclear facilities.

[0050] The nano-bimetallic composite remover produced by the present invention is a composite bimetallic material with high selectivity, which can be effectively used to remove cesium from wastewater and reduce the cesium content in wastewater. Furthermore, the composition ratio of nano-bimetallic powder and alkaline activator can be adjusted according to needs. Its structure has a high specific surface area, high adsorption capacity and selectivity, so it can produce a more efficient cesium removal effect compared with removers produced by other methods.

[0051] Accordingly, the present invention is a method for reducing or removing cesium in wastewater solutions. The nano-bimetallic composite remover has excellent performance and the composition ratio of nano-bimetallic powder and alkaline activator can be easily controlled to achieve good efficiency. It has good chemical stability and mechanical strength, and the operation process for adsorbing cesium ions is simple. It has obvious advantages for extracting cesium ions from wastewater.

[0052] In summary, the present invention is a method for preparing a nano-bimetallic composite removal agent for removing cesium-containing wastewater. It can effectively improve the various shortcomings of conventional methods, and can remove radioactive cesium nuclei from water samples or during accidents in general nuclear power plants or facilities. It can effectively reduce the risk of wastewater discharge with radioactive cesium pollution and meet the discharge standards. Therefore, the present invention is more advanced, more practical and more in line with the needs of users. It has met the requirements for an invention patent application, and a patent application is hereby filed in accordance with the law.

[0053] However, the above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the specification of the present invention should still fall within the scope of the patent of the present invention. [Simplified Explanation of the Diagram]

[0054] Figure 1 is a schematic diagram of the manufacturing process of the nano-bimetallic composite remover of the present invention. Figure 2 is a schematic diagram of the mechanical strength of the nano-bimetallic composite remover of the present invention. Figure 3 is a test diagram of the continuous cesium removal adsorption efficiency of the present invention using the nano-bimetallic composite remover.

Claims

1. A method for preparing a nano-bimetallic composite remover, comprising at least the following steps: Step 1: Dissolving two transition metal chloride salts with concentrations between 0.1 and 2.0 M as co-precipitation substrates in water, dissolving at a low temperature of 25-65°C and maintaining a constant temperature to form a bimetallic solution; dissolving a ferrocyanide with a concentration between 0.1 and 1.5 M in water to form a ferrocyanide solution, slowly adding the ferrocyanide solution to the bimetallic solution for reaction, wherein the ratio of the ferrocyanide solution to the bimetallic solution is 0.5-3.5; after stirring for 4-16 hours, filtering and washing the precipitate with water to remove residual unreacted reagents, drying at a low temperature of 85-125°C, and grinding to prepare a nano-scale bimetallic powder; wherein, The transition metal chloride salt is selected from at least two soluble salts from the group consisting of nickel chloride, cobalt chloride, ferric chloride, and potassium chloride; the bimetallic solution is an aqueous solution containing at least one bimetallic compound from the group consisting of bimetallic nitrate, bimetallic sulfate, bimetallic acetate, and bimetallic chloride; the ferrocyanide is selected from at least one from the group consisting of potassium ferrocyanide, sodium ferrocyanide, copper ferrocyanide, potassium titanium ferrocyanide, and nickel ferrocyanide; Step 2: The silicate aluminate material is calcined and activated at a high temperature of 600~900°C to become an amorphous structure. The nano-scale bimetallic powder is mixed with the calcined and activated silicate aluminate material in a ratio of 1~5:1, and then 1~5 The alkaline activator M is stirred and mixed evenly to form a paste-like polymerization mixture; wherein, the silicate aluminate material is metakaolin, and the alkaline activator is sodium metasilicate solution; and step three: the paste-like polymerization mixture is coated onto a template with an array of 1~2 mm holes, and polymerized and cured at room temperature for 1~3 hours. After curing and demolding, the nano bimetallic composite remover with a particle size of 1~2 mm is completed.

2. The method for preparing the nano-bimetallic composite remover as described in claim 1, wherein, The average particle size of this nanoscale bimetallic powder is 40 ± 20% nm.

3. The method for preparing the nano-bimetallic composite remover as described in claim 1, wherein, The composition ratio of the nano-bimetallic composite remover to the alkaline activator can be adjusted according to requirements to regulate the polymerization, curing, and granulation ratio.

4. A nano-bimetallic composite remover, which is prepared by any one of the preparation methods described in claims 1 to 3, having a BET (Brunauer-Emmett-Teller) specific surface area of ​​at least 35 m2 / g and a mechanical strength of at least 0.71 kgf / mm.

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