Device and method for concentrating radionuclides in seawater

Abstract

The invention relates to the technical field of water treatment and radiation monitoring, and discloses a concentration device and method for radionuclides in seawater, the concentration device comprises an anode flow electrode unit, a cation exchange membrane, an intermediate chamber, an anion exchange membrane and a cathode flow electrode unit which are sequentially arranged in parallel; wherein the anode flowing electrode unit comprises an anode plate and a first titanium mesh which are arranged in parallel; the first titanium mesh is positioned between the anode plate and the cation exchange membrane; the cathode flowing electrode unit comprises a second titanium mesh and a cathode plate which are arranged in parallel; and the second titanium mesh is positioned between the negative plate and the anion exchange membrane. The flowing electrode is adopted, ions in water enter the flowing electrode through the ion exchange membrane and are adsorbed through an external electric field, and concentration of nuclides in seawater is achieved; and by introducing the titanium mesh, the migration speed of the radionuclides is increased, so that the concentration efficiency of the radionuclides is further improved.

Description

Technical Field

[0001] The present invention relates to the fields of water treatment technology and radiation monitoring technology, and in particular to a device and method for concentrating radioactive nuclides in seawater. Background Art

[0002] Since the current content of radioactive nuclides in seawater is at trace levels, such as strontium-90, which is about 9.8 × 10 -16 g / L, cesium-137 is about 3.1 × 10 -15 g / L, the sensitivity of existing detection instruments is not enough to directly and quickly detect radionuclides with such low content.

[0003] The current mainstream method of radionuclide detection is to concentrate the water samples obtained, and then conduct detection after the radionuclide in the water samples is concentrated hundreds of times.

[0004] There are three main traditional methods for radionuclide concentration: evaporation, membrane separation, and adsorption. However, evaporation equipment is susceptible to corrosion and scaling, posing a potential explosion hazard. Membrane separation suffers from long operating cycles and high energy consumption. When adsorbing radionuclides, the surface active sites of traditional adsorbents are easily deactivated by interfering components such as salt in the water sample.

[0005] Capacitive deionization technology is a highly efficient electrochemical adsorption method that drives the migration of ions in water to the electrode surface by applying an external electric field, achieving selective adsorption and removal. In the adsorption stage, the electric field causes the ions to be adsorbed by the electrodes separately; in the desorption stage, the adsorbed ions are released by removing the potential difference or applying a reverse voltage. Compared with traditional methods, this technology has the advantages of low energy consumption and simple operation, and can achieve more efficient and precise concentration effects in the field of nuclide concentration. However, this technology has problems such as electrode saturation, common ion rejection, double layer effect, and electrode redox reaction. To address these shortcomings, membrane capacitive deionization technology introduces an ion exchange membrane between the electrode and the feed liquid to avoid the formation of a double layer, reduce the common ion rejection effect, and protect the electrode from oxidation, thereby improving system stability.

[0006] Despite this, existing capacitive deionization and membrane capacitive deionization technologies still face the problems of electrode saturation and limited adsorption capacity. In the process of concentrating trace radionuclides, they cannot meet the efficiency requirements of increasing the concentration of radionuclides by hundreds of times.

[0007] Therefore, there is an urgent need to develop radionuclide enrichment technologies with stronger adsorption performance. Summary of the Invention

[0008] In order to solve the above technical problems, the present invention provides a device for concentrating radionuclides in seawater, comprising an anode flow electrode unit, a cation exchange membrane, an intermediate chamber, an anion exchange membrane and a cathode flow electrode unit arranged in parallel; wherein, The anode flow electrode unit includes an anode plate and a first titanium mesh arranged in parallel; The first titanium mesh is located between the anode plate and the cation exchange membrane; The cathode flow electrode unit includes a second titanium mesh and a cathode plate arranged in parallel; The second titanium mesh is located between the cathode plate and the anion exchange membrane; The anode flow electrode unit further includes a first carbon fiber, wherein the first carbon fiber is located between the first titanium mesh and the cation exchange membrane; The cathode flow electrode unit further includes a second carbon fiber, and the second carbon fiber is located between the second titanium mesh and the anion exchange membrane.

[0009] Preferably, the mesh size of the first titanium mesh and the second titanium mesh are both 100-200 meshes.

[0010] Preferably, edges of the grids on the first titanium mesh and the second titanium mesh are provided with protruding structures.

[0011] Preferably, a hydrophobic conductive layer is provided on the surface of the first titanium mesh and the second titanium mesh.

[0012] Preferably, the hydrophobic conductive layer is a graphene layer.

[0013] Preferably, a third carbon fiber is provided in the intermediate cavity.

[0014] Preferably, the anode flow electrode unit further comprises an anode clamp located outside the anode plate, and a first pipe connection port is provided on the anode clamp; the cathode flow electrode unit further comprises a cathode clamp located outside the cathode plate, and a second pipe connection port is provided on the cathode clamp.

[0015] Preferably, electrode liquid is provided in both the anode flow electrode unit and the cathode flow electrode unit; the electrode liquid includes electrode material.

[0016] Preferably, the electrode liquid further includes a conductive additive.

[0017] Another object of the present application is to provide a method for concentrating radioactive nuclides in seawater, and to perform concentration according to the above-mentioned device for concentrating radioactive nuclides in seawater.

[0018] The embodiments of the present invention have the following technical effects: The device for concentrating radioactive nuclides in seawater provided in the present application adopts mobile electrode capacitive deionization technology, breaking the limitations of traditional fixed electrodes. By using mobile electrodes, an external electric field is used to allow ions in water to pass through the ion exchange membrane into the mobile electrode and be adsorbed, thereby achieving the concentration of nuclides in seawater. Compared with traditional fixed electrode technology, mobile electrode capacitive deionization technology has the advantages of scalable scale, unlimited adsorption capacity, continuous operation and low energy consumption. It is particularly suitable for the efficient concentration of radioactive nuclides, and provides an innovative solution for the rapid concentration of radioactive nuclides and the sustainable development of seawater resources. At the same time, the present application improves the migration efficiency of radioactive nuclides by introducing titanium mesh, thereby further improving the concentration efficiency of radioactive nuclides. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A schematic diagram of the structure of a radionuclide concentration device in seawater provided by an embodiment of the present invention; Figure 2 Schematic diagram of the concentration process of radionuclides in seawater according to an embodiment of the present invention; Figure 3 Schematic diagram of the change in conductivity of the target material to be treated by the medium concentration device in Example 1 of the present invention; Figure 4 Schematic diagram of the change in conductivity of the target material to be treated by the medium concentration device in Example 2 of the present invention; Figure 5 is the desalination efficiency at different intermediate chamber flow rates in Example 4 of the present invention; Figure 6 This is a comparison chart of the average desalination rate under each device configuration; Figure 7 This is a comparison chart of the energy-normalized desalination capacity under each device configuration; Figure 8 is a comparison chart of charge efficiency under various device configurations; Figure 9 This is a comparison chart of the final salt removal ratio under each device configuration.

[0021] In the figure: 1-anode flow electrode unit; 11-anode plate; 12-first titanium mesh; 13-first carbon fiber; 14-anode splint; 141-first pipe connection port; 15-anode insulating gasket; 2-cation exchange membrane; 3-middle chamber; 4-anion exchange membrane; 5-cathode flow electrode unit; 51-cathode plate; 52-second titanium mesh; 53-second carbon fiber; 54-cathode splint; 541-second pipe connection port; 55-cathode insulating gasket; 6-electrode liquid storage tank; 7-heating unit; 8-water storage tank. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are considered to be within the scope of the present invention.

[0023] Based on the problem that the existing deionization technology is difficult to meet the demand for increasing the concentration of radionuclides in the process of concentrating trace radionuclides, this application provides a device for concentrating radionuclides in seawater, see Figure 1 As shown, the concentration device includes an anode flow electrode unit 1, a cation exchange membrane 2, an intermediate chamber 3, an anion exchange membrane 4 and a cathode flow electrode unit 5 which are arranged in parallel in sequence; Among them, the intermediate chamber 3 is the input channel for the seawater to be treated containing radionuclides, and is sandwiched by a cation exchange membrane 2 and an anion exchange membrane 4; the cation exchange membrane 2 and the anion exchange membrane 4 are used to selectively separate different ions to ensure that specific ions enter the corresponding flow electrode units; specifically, the cation exchange membrane 2 is combined with the anode flow electrode unit 1 to form an anode flow channel for separating positively charged radionuclides; the anion exchange membrane 4 is combined with the cathode flow electrode unit 5 to form a cathode flow channel for separating negatively charged radionuclides; during operation, the seawater to be treated is input into the intermediate chamber 3 by a peristaltic pump, and a DC voltage is applied to the anode flow electrode unit 1 and the cathode flow electrode unit 5 on both sides. Under the action of the electric field, the positively charged radionuclides in the seawater to be treated enter the anode flow electrode unit 1 after passing through the cation exchange membrane 2, and the positively charged radionuclides are concentrated in the anode flow electrode unit 1; the negatively charged radionuclides in the seawater to be treated enter the cathode flow electrode unit 5 after passing through the anion exchange membrane 4, and the negatively charged radionuclides are concentrated in the cathode flow electrode unit 5.

[0024] In order to improve the concentration efficiency, the present application preferably comprises an anode flow electrode unit 1 including an anode plate 11 and a titanium mesh arranged in parallel, which are recorded as the first titanium mesh 12 for easy distinction; the first titanium mesh 12 is located between the anode plate 1111 and the cation exchange membrane 2; correspondingly, the cathode flow electrode unit 5 comprises a titanium mesh arranged in parallel, which are recorded as the second titanium mesh 52 and the cathode plate 51 for easy distinction; the second titanium mesh 52 is located between the cathode plate 51 and the anion exchange membrane 4.

[0025] During operation, a DC voltage is applied to the anode plate 11 and the cathode plate 51 to provide an electric field, forming an anode flow channel between the anode plate 11 and the cation exchange membrane 2 , and a cathode flow channel between the cathode plate 51 and the anion exchange membrane 4 .

[0026] Furthermore, the anode flow electrode unit 1 in the present application also includes an insulating gasket, which is recorded as an anode insulating gasket 15; the anode insulating gasket 15 is located between the anode plate 11 and the first titanium mesh 12; accordingly, the cathode flow electrode unit 5 also includes an insulating gasket, which is recorded as a cathode insulating gasket 55; the cathode insulating gasket 55 is located between the cathode plate 51 and the second titanium mesh 52.

[0027] The titanium mesh in the present application is provided with several grid structures; the raised edges of each grid structure in the titanium mesh are used to gather charges, thereby enhancing the strength of the local electric field, thereby increasing the migration speed of radioactive nuclides, and further improving the concentration efficiency of radioactive nuclides.

[0028] The device for concentrating radioactive nuclides in seawater provided in the present application adopts mobile electrode capacitive deionization technology, breaking the limitations of traditional fixed electrodes. By using mobile electrodes, an external electric field is used to allow ions in water to pass through the ion exchange membrane into the mobile electrode and be adsorbed, thereby achieving the concentration of nuclides in seawater. Compared with traditional fixed electrode technology, mobile electrode capacitive deionization technology has the advantages of scalable scale, unlimited adsorption capacity, continuous operation and low energy consumption. It is particularly suitable for the efficient concentration of radioactive nuclides, and provides an innovative solution for the rapid concentration of radioactive nuclides and the sustainable development of seawater resources. At the same time, the present application introduces titanium mesh to increase the migration speed of radioactive nuclides, thereby further improving the concentration efficiency of radioactive nuclides.

[0029] Furthermore, the present application preferably includes an activated carbon fiber in the anode flow electrode unit, which is designated as the first carbon fiber 13 for easy distinction. The first carbon fiber 13 is located between the first titanium mesh 12 and the cation exchange membrane 2. The size of the first carbon fiber 13 is determined according to the size of the anode flow electrode unit 1 so that the first carbon fiber 13 is compatible with the anode flow electrode unit 1. By providing the first carbon fiber 13, on the one hand, it plays a role in promoting mass transfer and improving the mass transfer efficiency and ion migration effect. On the other hand, it also plays a buffering role, preventing the first titanium mesh 12 from directly contacting the cation exchange membrane 2, thereby avoiding the first titanium mesh 12 from damaging the cation exchange membrane 2 and extending the service life of the device.

[0030] Similarly, the present application preferably configures the cathode flow electrode unit to also include activated carbon fibers, which are designated as second carbon fibers 53 for ease of distinction. The second carbon fibers 53 are located between the second titanium mesh 52 and the anion exchange membrane 4. The size of the second carbon fibers 53 is determined according to the size of the cathode flow electrode unit 5, so that the second carbon fibers 53 are compatible with the cathode flow electrode unit 5. By providing the second carbon fibers 53, on the one hand, it promotes mass transfer and improves mass transfer efficiency and ion migration effect. On the other hand, it also acts as a buffer to prevent the second titanium mesh 52 from directly contacting the anion exchange membrane 4, thereby avoiding damage to the anion exchange membrane 4 by the second titanium mesh 52 and extending the service life of the device.

[0031] It should be noted that the titanium mesh and activated carbon fiber in this application do not work alone, but work together to further improve the mass transfer efficiency; the activated carbon fiber can form a three-dimensional network with high porosity on the surface of the titanium mesh, and this network has a pore structure of micron to submicron level. These pore structures not only help to enhance permeability and shorten the diffusion distance, but also the random orientation and staggered structure of the fibers in the activated carbon fiber will disturb the laminar flow, generate micro-eddies, destroy the boundary layer, and strengthen the diffusion of ions / molecules to the active sites, which plays a role in promoting turbulence, thereby enhancing the penetration and mixing at the microscopic scale through the activated carbon fiber, while shortening the diffusion path; the titanium mesh in this application enhances the migration speed of radioactive nuclides by strengthening the effect of charge aggregation, thereby optimizing the fluid distribution from a macroscopic perspective; the combination of titanium mesh and activated carbon fiber significantly improves the mass transfer efficiency by constructing a hierarchical mass transfer structure combining macroscopic diversion with microscopic diffusion, thereby improving the concentration efficiency.

[0032] The preferred thickness range of the activated carbon fiber in this application is 7-15 mm.

[0033] In the present application, the mesh size of the first titanium mesh 12 and the second titanium mesh 52 is preferably 100-200 mesh, and the thickness of the first titanium mesh 12 and the second titanium mesh 52 is preferably in the range of 2-4 mm.

[0034] In order to enhance the charge aggregation effect and thus improve the concentration efficiency of radionuclides, the present application preferably provides a protrusion structure on the edge of each grid in the first titanium mesh 12 and the second titanium mesh 52 so as to further enhance the charge aggregation effect by utilizing the protrusion structure.

[0035] Furthermore, the addition of titanium mesh can easily lead to an increase in fluid resistance; to avoid the increase in fluid resistance, the present application preferably has a hydrophobic conductive layer on the surface of the titanium mesh so as to reduce slurry adhesion and prevent pore clogging while ensuring its effect on charge aggregation.

[0036] Specifically, the present application preferably adopts a hydrophobic conductive layer as a graphene layer, and preferably introduces a graphene layer onto the surface of the titanium mesh by vapor deposition.

[0037] The specific vapor deposition method can adopt the corresponding existing technology, and this application does not limit the vapor deposition method.

[0038] At the same time, the setting of the raised structure can further increase the surface area, and combined with the graphene layer set on its surface, it helps to further improve the mass transfer efficiency while avoiding an increase in fluid resistance.

[0039] In this application, the sizes of the first titanium mesh 12 and the second titanium mesh 52 are determined according to the sizes of the corresponding anode flow electrode unit 1 and cathode flow electrode unit 5, so that the first titanium mesh 12 and the second titanium mesh 52 are respectively adapted to the anode flow electrode unit 1 and the cathode flow electrode unit 5.

[0040] In addition, the present application preferably also provides activated carbon fibers in the intermediate chamber 3, which are referred to as third carbon fibers (not shown in the figure) for easy distinction; the size of the third carbon fibers is determined according to the size of the intermediate chamber 3 so that the third carbon fibers are compatible with the intermediate chamber 3; by providing the third carbon fibers, the mass transfer efficiency is improved, so that the device can operate at an operating voltage far exceeding the hydrogen / oxygen evolution potential, and still maintain a high-speed concentration effect at the over-limit potential, so as to further enhance the adsorption effect of nuclides and the fluid mass transfer performance.

[0041] For ease of operation, the present application further prefers that the anode flow electrode unit 1 also includes an anode clamp 14 located on the outside of the anode plate 11, wherein the outside of the anode plate 11 specifically refers to the side of the anode plate 11 away from the anode insulating gasket 15, and specifically, the anode clamp 14 and the anode insulating gasket 15 are respectively located on both sides of the anode plate 11; the anode clamp 14 is provided with a pipe connection port, which is recorded as a first pipe connection port 141, and the number of the first pipe connection port 141 is two, so as to facilitate the input and output of the electrode liquid through the two first pipe connection ports 141; correspondingly, the cathode flow electrode unit 5 also includes a cathode clamp 54 located on the outside of the cathode plate 51, wherein the outside of the cathode plate 51 specifically refers to the side of the cathode plate 51 away from the cathode insulating gasket 55, and specifically, the cathode clamp 54 and the cathode insulating gasket 55 are respectively located on both sides of the cathode plate 51; the cathode clamp 54 is provided with a pipe connection port, which is recorded as a second pipe connection port 541, and the number of the second pipe connection port 541 is two, so as to facilitate the input and output of the electrode liquid through the two second pipe connection ports 541. The anode clamping plate 14 and the cathode clamping plate 54 together form a clamp of the concentration device to fix the components.

[0042] In order to achieve the concentration of radioactive nuclides, electrode liquid is provided in the anode flow electrode unit 1 and the cathode flow electrode unit 5 in the present application; the electrode liquid continuously flows in the flow channels of the anode flow electrode unit 1 and the cathode flow electrode unit 5, adsorbs ions in the water and carries them out of the electric field area; specifically, in the anode flow electrode unit 1, the electrode liquid enters the anode flow channel from a first pipe connection 141 on the anode clamp 14, and after concentrating the positively charged nuclides through the anode plate 11, the first titanium mesh 12 of the anode insulating gasket 15 and the first carbon fiber 13, it is output from another first pipe connection 141 on the anode clamp 14; similarly, in the cathode flow electrode unit 5, the electrode liquid enters the cathode flow channel from a first pipe connection 541 on the cathode clamp 54, and after concentrating the negatively charged nuclides through the cathode plate 51, the second titanium mesh 52 of the cathode insulating gasket 55 and the second carbon fiber 53, it is output from another first pipe connection 541 on the cathode clamp 54.

[0043] The present application prefers that the electrode liquid is a mixed slurry, and further prefers that the slurry includes a mobile electrode material with high electrochemical adsorption properties, that is, the electrode liquid includes an electrode material, so that under the action of the electric field, the nuclides are adsorbed by the charged electrode material to achieve the concentration of the nuclides. In order to further improve the adsorption effect on nuclides, the present application preferably includes a conductive additive with high conductivity in the electrode solution to further improve the concentration efficiency.

[0044] Specifically, the present application prefers that the electrode material is selected from at least one of activated carbon, magnetic activated carbon, covalent organic framework material-loaded activated carbon, and g-C3N4-loaded activated carbon; the conductive additive is preferably selected from at least one of carbon black, graphene oxide, carbon nanotubes, carbon aerogel, g-C3N4-loaded graphene oxide, and covalent organic framework material-loaded graphene oxide; and further prefers that the mass fraction of the electrode material in the electrode liquid is 5~15wt%, and the mass fraction of the conductive additive is 0.5~1.5wt%.

[0045] See also Figure 2 As shown, in order to achieve the concentration of nuclides, the present application preferably further includes an electrode liquid storage tank 6, a heating unit 7 and a water storage tank 8 for the concentration of radioactive nuclides in seawater; wherein the electrode liquid storage tank 6 is connected to the anode clamp 14 and the cathode clamp 54, so as to facilitate the continuous concentration of nuclides by the circulation of the electrode liquid in the anode flow channel and the cathode flow channel; in order to achieve the connection between the electrode liquid storage tank 6 and the anode flow electrode unit and the cathode flow electrode unit, the electrode liquid storage tank 6 is preferably connected to the first pipe port 141 and the second pipe port 541, which are used for the entry and exit of the target nuclide ion extraction electrode liquid, so as to achieve the separation and concentration of nuclides. The heating unit 7 is located below the electrode liquid storage tank 6 and is used to maintain the temperature of the electrode liquid. The water storage tank 8 is connected to the intermediate chamber 3.

[0046] During operation, the electrode liquid is pumped from the electrode liquid storage tank 6 into the anode flow channel and the cathode flow channel respectively, and then pumped out from the two flow channels and flows back to the electrode liquid storage tank 6. The target concentrated nuclides in the water storage tank 8 are pumped into the intermediate chamber 3, and after separation and concentration, they are pumped out of the intermediate chamber 3 and flow back to the water storage tank 8.

[0047] It should be noted that, in order to simplify the structure, Figure 2 It is only used to illustrate the nuclide concentration process, and does not show the detailed structure of the titanium mesh, activated carbon fiber and ion exchange membrane in the concentration device.

[0048] The device for concentrating radioactive nuclides in seawater provided by the present invention is capable of concentrating radioactive nuclides such as uranium, thorium, radium, cesium, and strontium in seawater. The concentrating device utilizes the charge-aggregating effect of the titanium mesh to enhance the strength of the local electric field, thereby increasing the migration speed of the radioactive nuclides. By introducing activated carbon fibers into the mobile electrode capacitor deionization device, it is possible to operate at an operating voltage far exceeding the hydrogen / oxygen evolution potential, further enhancing the electrode's adsorption capacity for nuclides. At the same time, the screening effect of the ion exchange membrane effectively guides the nuclides in the intermediate chamber into the mobile electrode chamber. Under the action of the electric field, the charged electrode material adsorbs these nuclides, completing the concentration process. The concentration device provided by the present invention has the advantages of simple process and high nuclide concentration efficiency. The operation process is environmentally friendly and has no secondary pollution. It can achieve efficient concentration of radioactive nuclides in seawater and facilitates rapid and accurate detection of the radioactive nuclide content.

[0049] Another object of the present invention is to provide a method for concentrating radioactive nuclides in seawater, which comprises concentrating the radioactive nuclides in seawater using the device for concentrating radioactive nuclides in seawater as described above.

[0050] Specifically, the concentration method can be carried out according to the following process: The configured electrode liquid is introduced from the electrode liquid storage tank 6 into the anode flow channel and the cathode flow channel respectively through a peristaltic pump, and the seawater to be treated containing radioactive nuclides is introduced from the water storage tank 8 into the intermediate chamber 3 through a peristaltic pump; a DC voltage is applied to the anode plate 11 and the cathode plate 51. Under the action of the electric field, the positively charged nuclides in the seawater to be treated migrate to the anode flow channel after passing through the cation exchange membrane 2 and are adsorbed by the electrode liquid, thereby achieving the concentration of the positively charged nuclides; the negatively charged nuclides in the seawater to be treated migrate to the cathode flow channel after passing through the anion exchange membrane 4 and are adsorbed by the electrode liquid, thereby achieving the concentration of the negatively charged nuclides. The separated and concentrated seawater is pumped out of the intermediate chamber 3 and returned to the water storage tank 8.

[0051] This concentration method can release the adsorbed nuclides through a reverse electric field or chemical method, while achieving electrode regeneration and continuous nuclide concentration.

[0052] Specifically, the present application preferably applies a DC working voltage of 1.2 to 6.0 V to the flow electrode chamber, and preferably the pump flow rate of the flow electrode chamber during operation is 1 to 300 mL / min, and the pump flow rate of the intermediate chamber is 1 to 100 mL / min. The method for concentrating radioactive nuclides in seawater provided in the present application adopts mobile electrode capacitive deionization technology, breaking the limitations of traditional fixed electrodes. By using mobile electrodes, an external electric field is used to allow ions in water to pass through the ion exchange membrane into the mobile electrode and be adsorbed, thereby achieving the concentration of nuclides in seawater. Compared with traditional fixed electrode technology, mobile electrode capacitive deionization technology has the advantages of scalable scale, unlimited adsorption capacity, continuous operation and low energy consumption. It is particularly suitable for the efficient concentration of radioactive nuclides, and provides an innovative solution for the rapid concentration of radioactive nuclides and the sustainable development of seawater resources. At the same time, the present application improves the migration efficiency of radioactive nuclides by introducing titanium mesh, thereby further improving the concentration efficiency of radioactive nuclides.

[0053] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the application are described in detail below.

[0054] The following examples are all Figure 1 The device is used for concentration.

[0055] A graphene layer is deposited on the surface of the titanium mesh in each embodiment of the present application.

[0056] Example 1 (a) A 1-liter NaCl solution with a concentration of 0.5 g / L was introduced into the middle chamber 3 of the concentration device via a circulation pump. Simultaneously, 0.1 L of an electrode solution consisting of 5 wt% activated carbon and deionized water was pumped into the anode flow channel and the cathode flow channel, respectively.

[0057] The operating conditions of the device were set as a DC voltage of 6.0 V, a flow rate of 250 mL / min in the middle chamber 3, a flow rate of 100 mL / min in the anode flow channel and the cathode flow channel, and the electrode solution temperature was maintained at 40 °C.

[0058] (b) Run under the above conditions for 2 hours, the experimental results are as follows Figure 3 After 56 minutes of operation, the conductivity of the NaCl solution decreased by 90%, that is, the salt removal rate reached 90%. At this time, the device's concentration factor for the NaCl solution is theoretically 9 times. After 2 hours of operation, the salt removal rate reached 99%, corresponding to a theoretical concentration factor of 9.9 times.

[0059] Example 2 (a) An 8-liter NaCl solution with a concentration of 0.5 g / L was introduced into the middle chamber 3 of the concentration device via a circulation pump. Simultaneously, 0.08 L of an electrode solution consisting of 5 wt% activated carbon and deionized water was pumped into the anode flow channel and the cathode flow channel, respectively.

[0060] The operating conditions of the device were set as a DC voltage of 4.8 V, a flow rate of 250 mL / min in the middle chamber 3, a flow rate of 100 mL / min in the anode flow channel and the cathode flow channel, and the electrode solution temperature was maintained at 40 °C.

[0061] (b) The experimental results are as follows: Figure 4 After 10 hours of operation, the conductivity of the NaCl solution dropped by 90%, that is, the salt removal rate reached 90%. At this time, the concentration multiple of the device for NaCl solution theoretically reached 90 times.

[0062] Example 3 (a) A certain volume of seawater is collected, filtered, and acidified. 60 L of seawater is pumped into the middle chamber 3 of the concentration device. The prepared electrode solution, consisting of 5 wt% activated carbon and deionized water, is pumped into the anode and cathode flow channels.

[0063] The operating conditions were set as follows: DC voltage 3.0 V, flow rate of the middle chamber 3 1000 mL / min, flow rate of the anode flow channel and cathode flow channel 500 mL / min, electrode liquid temperature 40 °C, (b) After 20 hours of operation under the corresponding conditions, the seawater conductivity dropped by 90%, and the radioactive elements in the seawater were concentrated into the electrode liquid with a concentration factor of 90.

[0064] Example 4 (a) A 100 mL volume of 1.0 g / L NaCl solution was injected into the middle chamber of the concentration device through a circulation pump. At the same time, a 100 mL electrode solution consisting of 5 wt% activated carbon and deionized water was pumped into the flow electrode chamber.

[0065] The operating conditions of the device were set as a DC voltage of 6.0 V, an intermediate chamber flow rate of 50-250 mL / min, a flow rate of 50 mL / min in the flow electrode chamber, and the electrode liquid temperature was maintained at room temperature; the currents at different intermediate chamber flow rates are shown in Table 1.

[0066] (b) Run continuously for 15 minutes under the above conditions. The experimental results are as follows: Figure 5 As shown. Figure 5 It can be seen that appropriately increasing the flow rate in the intermediate chamber can effectively promote the ion renewal rate, thereby significantly improving the desalination effect of the concentration device.

[0067] Table 1

[0068] In order to further understand the advantages of the radioactive nuclide concentration device in seawater provided by this application, the desalination effect of the concentration device provided by this application is compared with that of concentration devices with other structures. The configuration numbers of the mobile electrode capacitor deionization device and their specific meanings are shown in Table 2.

[0069] Table 2

[0070] Wherein "T,CCC,T" is the device configuration number provided in this application.

[0071] Desalination treatment was performed using the devices in Table 2 according to the following methods: A 100 mL volume of 3.5 g / L NaCl solution was injected into the middle chamber of the flow electrode capacitive deionization device through a circulation pump. At the same time, 50 mL of electrode solution consisting of 5 g activated carbon, 45 g deionized water and 0.175 g NaCl was pumped into the flow electrode chamber.

[0072] The operating conditions of the device were set as a DC voltage of 2.0 V, a flow rate of 200 mL / min in the intermediate chamber, a flow rate of 100 mL / min in the flow electrode chamber, a time of 6 minutes, and the electrode solution temperature was maintained at 25 °C.

[0073] In this application, the average salt removal rate (ASRR, μmol cm -2 min -1 ) and energy-normalized removed salt (ENRS, μmol J -1 ), charge efficiency (CE, %) and salt removal efficiency (SRE, %) were used to evaluate the desalination performance of the FCDI system.

[0074] The calculation formula for the above indicators is as follows: ; ASRR represents the system's desalination capacity per unit membrane area per unit time, and its value directly reflects the speed of treatment.

[0075] ; ENRS stands for energy consumption and desalination, reflecting energy utilization efficiency.

[0076] ; CE stands for charge utilization efficiency.

[0077] ; SRE represents the final salt removal ratio of the system, which measures the thoroughness of desalination.

[0078] Where C0 and C t Represent the salt concentration (g / L) at the initial moment and time t, V s is the volume of brine (100 mL), M is the molar mass of NaCl (58.69 g / mol), and A represents the effective contact area between the flow electrode and the ion exchange membrane (54 cm 2 ), t is the running time (s), I t is the transient current flowing through the FCDI system (A), U is the applied constant voltage (V), and F is the Faraday constant (96485 C / mol).

[0079] Under different device configurations, the ASRR, ENRS, CE and SRE values ​​of the flow electrode capacitive deionization device under different configurations are as follows: Figure 6-Figure 9 shown.

[0080] See also Figure 6 As shown in the experimental results, the T, CCC, T (device provided in this application) configuration exhibits the highest average salt rejection rate (ASRR), indicating that this structure has the best desalination performance. It is worth noting that although the T, T, CCC, T, T configuration adds two layers of titanium mesh on the basis of T, CCC, T, its desalination efficiency is significantly reduced. This phenomenon is Figure 9 This decline in efficiency was further validated by the desalination efficiency data from the 2017 study. This decline in efficiency may be due to the excessive number of titanium mesh layers, which resulted in an overly dense flow channel structure within the flow electrode chamber, leading to channel blockage and hindering charge transfer and ion migration. This finding suggests that in the design of flow electrode capacitive deionization devices, the use of titanium mesh requires a balance between its conductivity enhancement and flow channel patency; excessive stacking can compromise the overall system performance.

[0081] Experimental data show that the ASRR value of the T,CCC,T configuration is almost twice that of the TCT configuration. This significant difference reveals the key role of activated carbon fibers at the electrode liquid chamber end in improving desalination efficiency. The introduction of activated carbon fibers effectively enhances the mass transfer efficiency between the electrode liquid chamber and the ion exchange membrane interface, significantly improving the overall desalination performance of the system.

[0082] The experimental results show that the ASRR value of the pure activated carbon fiber configuration (CCC) is significantly lower than that of the T, CCC, and T configurations. Although the activated carbon fiber itself has good mass transfer properties, this difference indicates that the titanium mesh not only plays a role in assisting mass transfer in the system, but more importantly, its unique flow channel structure optimizes the flow path of the electrode solution, thereby synergistically improving the overall desalination efficiency.

[0083] Experimental results demonstrate that the presence of activated carbon fibers in the intermediate chamber has a crucial impact on system performance. Comparing the performance of the T,C-0-C,T configuration (without the conductive intermediate chamber) with the standard configuration reveals that removing the activated carbon fibers significantly reduces desalination efficiency. This phenomenon confirms the dual function of the activated carbon fibers at the intermediate chamber end: they act as ion and mass transfer enhancers, effectively preventing concentration polarization, and as charge carriers, maintaining the continuity of the electrochemical reaction.

[0084] A comparative analysis of the ENRS and CE values ​​for different configurations revealed that, with the exception of the configuration where the intermediate chamber was not filled with a conductive medium, the numerical differences for the remaining configurations were relatively small. This result demonstrates that the conductive intermediate composed of the titanium mesh and activated carbon fiber plays a key role in promoting mass transfer in the system. In the optimal configuration (T, CCC, T), the synergistic effect of the titanium mesh and activated carbon fiber is particularly prominent: the titanium mesh not only provides an optimized fluid channel but also effectively enhances mass transfer efficiency in conjunction with the activated carbon fiber, significantly alleviating concentration polarization and thus improving overall system performance.

[0085] In summary, embodiments of the present invention provide a highly efficient method for concentrating radionuclides such as uranium, thorium, radium, cesium, and strontium in seawater. Through the synergistic effects of electric field enhancement, ion exchange, and adsorption in a mobile electrode capacitive deionization device, rapid concentration of seawater containing radionuclides such as uranium, thorium, radium, cesium, and strontium is achieved. The method of the present invention has significant efficiency advantages, enabling efficient concentration of radionuclides in a short period of time. It is also simple to operate, inexpensive, and environmentally friendly, providing a feasible path for the efficient development and comprehensive utilization of seawater resources and possessing broad prospects for industrialization.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A device for concentrating radionuclides in seawater, characterized in that: It comprises an anode flow electrode unit (1), a cation exchange membrane (2), an intermediate chamber (3), an anion exchange membrane (4), and a cathode flow electrode unit (5) which are arranged in parallel in sequence; wherein, The anode flow electrode unit (1) comprises an anode plate (11) and a first titanium mesh (12) arranged in parallel; The first titanium mesh (12) is located between the anode plate (11) and the cation exchange membrane (2); The cathode flow electrode unit (5) comprises a second titanium mesh (52) and a cathode plate (51) arranged in parallel; The second titanium mesh (52) is located between the cathode plate (51) and the anion exchange membrane (4); The anode flow electrode unit (1) further comprises a first carbon fiber (13), wherein the first carbon fiber (13) is located between the first titanium mesh (12) and the cation exchange membrane (2); The cathode flow electrode unit (5) further includes a second carbon fiber (53), and the second carbon fiber (53) is located between the second titanium mesh (52) and the anion exchange membrane (4).

2. The device for concentrating radioactive nuclides in seawater according to claim 1, characterized in that: The mesh sizes of the first titanium mesh (12) and the second titanium mesh (52) are both 100-200 meshes.

3. The device for concentrating radioactive nuclides in seawater according to claim 1, characterized in that: The edges of the meshes on the first titanium mesh (12) and the second titanium mesh (52) are provided with raised structures.

4. The device for concentrating radioactive nuclides in seawater according to claim 1, characterized in that: The surfaces of the first titanium mesh (12) and the second titanium mesh (52) are both provided with a hydrophobic conductive layer.

5. The device for concentrating radioactive nuclides in seawater according to claim 4, characterized in that: The hydrophobic conductive layer is a graphene layer.

6. The device for concentrating radioactive nuclides in seawater according to claim 1, characterized in that: A third carbon fiber is arranged in the middle chamber (3).

7. The device for concentrating radioactive nuclides in seawater according to any one of claims 1 to 6, characterized in that: The anode flow electrode unit (1) further comprises an anode clamp (14) located outside the anode plate (11), and a first pipe connection port (141) is provided on the anode clamp (14); the cathode flow electrode unit (5) further comprises a cathode clamp (54) located outside the cathode plate (51), and a second pipe connection port (541) is provided on the cathode clamp (54).

8. The device for concentrating radioactive nuclides in seawater according to any one of claims 1 to 6, characterized in that: Electrode liquid is provided in both the anode flow electrode unit (1) and the cathode flow electrode unit (5); the electrode liquid includes electrode material.

9. The device for concentrating radioactive nuclides in seawater according to claim 8, characterized in that: The electrode solution also includes a conductive additive.

10. A method for concentrating radionuclides in seawater, characterized in that: Concentration is carried out using the device for concentrating radioactive nuclides in seawater according to any one of claims 1 to 9.

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