A method for separating and enriching uranium from seawater, and an electrically driven membrane separation reaction system

Abstract

The present invention provides a method for separating and enriching uranium in seawater. Compared with the prior art, the present invention utilizes the advantages of an electro-dehydration electric-driven separation system to achieve the selective separation of ions of different valence states. By selecting a suitable cation exchange membrane type and current density, sodium chloride and uranium are selectively separated in one step; and by utilizing electro-dehydration, high water migration can be obtained to enhance the uranium enrichment effect; the method is simple to implement and has no harmful pollution to the environment. The characteristics of different ion exchange membranes can be utilized to achieve the separation of single and multivalent ions. The defect of the ion exchange membrane being not dense enough can also be cleverly utilized to turn disadvantages into advantages and reduce costs; at the same time, the electric field force is used as the driving force, the separation effect is better, the enrichment efficiency is greatly improved, and the problems of the traditional physical adsorption method are avoided. Therefore, the use of an electro-dehydration electro-membrane reactor to separate and enrich uranium from seawater is a green, environmentally friendly, and efficient method with important industrial application value.

Description

Technical Field

[0001] The invention belongs to the technical field of uranium separation and enrichment, and in particular relates to a method for separating and enriching uranium from seawater and an electrically driven membrane separation reaction system. Background Art

[0002] Uranium is an important raw material for nuclear power, but uranium mineral resources on land are very limited. Due to the scarcity and value of uranium resources, it is urgent to explore a new source of uranium as a supplement and guarantee of uranium resources. Among them, getting uranium from the ocean is a very important and promising source.

[0003] Seawater contains abundant uranium resources, about 4.5 billion tons, which is about 1,000 times the reserves on land. However, as a highly complex matrix, seawater has high ionic strength and complex composition, and contains a large number of competing ions. At the same time, the concentration of uranium in seawater is very low (only ~3.3 ppb), and it is very difficult to separate and enrich low-concentration uranium from seawater, which faces huge challenges. At present, the adsorption method using polymer adsorbents is considered to be a more effective method for enriching uranium from seawater. However, this traditional physical adsorption method has problems such as lack of driving force leading to low adsorption efficiency, difficulty in entering the adsorption site, and a large number of competing ions occupying the adsorption site, which greatly reduces the ability of the adsorbent to enrich uranium and limits its large-scale application in actual industrial production.

[0004] As a new and highly applicable advanced membrane separation technology, electromembrane technology uses the selective permeability of ion exchange membranes to generate an electromembrane-driven process to achieve selective separation of ions in solution. It has broad application prospects and has the advantages of high efficiency and energy saving, easy operation, easy integration with other technologies, and environmental friendliness. It provides a new solution for separating and enriching uranium from seawater. However, there are few reports on the separation and enrichment of uranium from seawater using electromembrane technology. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for separating and enriching uranium from seawater using an electrically driven membrane separation technology, and an electrically driven membrane separation reaction system.

[0006] The present invention provides a method for separating and enriching uranium in seawater, which is characterized by comprising:

[0007] An electro-dehydration electrically driven membrane separation reaction system is provided; the electro-dehydration electrically driven membrane separation reaction system comprises an anode chamber, a reactor membrane stack and a cathode chamber arranged in sequence;

[0008] The reactor membrane stack is connected to the anode chamber through a first cation exchange membrane;

[0009] The reactor membrane stack is connected to the cathode chamber through a second cation exchange membrane;

[0010] The reactor membrane stack comprises a reaction unit; the reaction unit comprises a concentration chamber and a desalination chamber arranged in sequence from the anode chamber to the cathode chamber; the desalination chamber and the concentration chamber are connected through a monovalent or polyvalent selective anion exchange membrane;

[0011] A solution to be concentrated is introduced into a desalination chamber in an electric dehydration and electric driven membrane separation reaction system, a sodium chloride solution is introduced into a concentration chamber, a first electrolyte solution is introduced into an anode chamber, and a second electrolyte solution is introduced into a cathode chamber, and a low-salinity and high-concentration uranium solution is obtained by electrodialysis;

[0012] The solution to be concentrated includes uranium element and sodium chloride.

[0013] Preferably, the concentration of sodium chloride in the solution to be concentrated is equal to the concentration of sodium chloride in the sodium chloride solution.

[0014] Preferably, the volume of the solution to be concentrated in the desalination chamber is greater than the volume of the sodium chloride solution in the concentration chamber.

[0015] Preferably, the pH value of the solution to be concentrated is 7.5-8.5.

[0016] Preferably, the first electrolyte solution and the second electrolyte solution are each independently a sodium sulfate solution; the concentration of the sodium sulfate solution is 0.01 to 1 mol / L.

[0017] Preferably, the linear speeds of the solution to be concentrated, the sodium chloride solution, the first electrolyte solution and the second electrolyte solution are independently 3 to 10 cm / s.

[0018] Preferably, the first cation exchange membrane and the second cation exchange membrane are independently selected from CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd., or CM-2 produced by Japan Astom Company;

[0019] The monovalent and multivalent selective anion exchange membrane is selected from the dense ASA produced by Astom Company of Japan.

[0020] Preferably, the current density of the electrodialysis is 4-10 mA / cm 2 .

[0021] Preferably, the number of the reaction units is greater than or equal to 2; and adjacent reaction units are connected via a cation exchange membrane.

[0022] The present invention also provides a method for separating and enriching uranium in seawater, comprising:

[0023] Providing an electric dehydration electrically driven membrane separation reaction system and an electrically driven membrane separation reaction system;

[0024] The electric dehydration and electric driven membrane separation reaction system comprises an anode chamber, a reactor membrane stack and a cathode chamber which are arranged in sequence;

[0025] The reactor membrane stack is connected to the anode chamber through the first cation exchange membrane;

[0026] The reactor membrane stack is connected to the cathode chamber through a second cation exchange membrane;

[0027] The reactor membrane stack comprises a reaction unit; the reaction unit comprises a concentration chamber and a desalination chamber arranged in sequence from the anode chamber to the cathode chamber; the desalination chamber and the concentration chamber are connected through a monovalent or polyvalent selective anion exchange membrane;

[0028] The electrically driven membrane separation reaction system comprises an electrically driven anode chamber, an electrically driven reactor membrane stack and an electrically driven cathode chamber which are arranged in sequence;

[0029] The electrically driven reactor membrane stack is connected to the anode chamber via a third cation exchange membrane;

[0030] The electrically driven reactor membrane stack is connected to the cathode chamber via a fourth cation exchange membrane;

[0031] The electrically driven reactor membrane stack comprises an electrically driven reaction unit; the electrically driven reaction unit comprises an electrically driven desalination chamber and an electrically driven concentration chamber arranged in sequence along the direction from the electrically driven anode chamber to the electrically driven cathode chamber; the electrically driven desalination chamber and the electrically driven concentration chamber are connected through an anion exchange membrane;

[0032] The solution to be concentrated is introduced into the desalination chamber of the electric dehydration and electric driven membrane separation reaction system, the sodium chloride solution is introduced into the concentration chamber, the first electrolyte solution is introduced into the anode chamber, and the second electrolyte solution is introduced into the cathode chamber to perform the first electrodialysis;

[0033] Passing the solution in the desalination chamber after the first electrodialysis into the electrically driven desalination chamber and the electrically driven concentrating chamber in the electrically driven membrane separation reaction system for a second electrodialysis;

[0034] The solution in the concentration chamber after the second electrodialysis is passed into the desalination chamber in the electric dehydration electric driven membrane separation reaction system, and at the same time, a sodium chloride solution is passed into the concentration chamber, a first electrolyte solution is passed into the anode chamber, and a second electrolyte solution is passed into the cathode chamber, and a third electrodialysis is performed to obtain a low-salinity and high-concentration uranium solution;

[0035] The solution to be concentrated includes uranium element and sodium chloride.

[0036] The invention provides a method for separating and enriching uranium in seawater, comprising: providing an electro-dehydration electrically driven membrane separation reaction system; the electro-dehydration electrically driven membrane separation reaction system comprises an anode chamber, a reactor membrane stack and a cathode chamber which are arranged in sequence; the reactor membrane stack is connected with the anode chamber through a first cation exchange membrane; the reactor membrane stack is connected with the cathode chamber through a second cation exchange membrane; the reactor membrane stack comprises a reaction unit; the reaction unit comprises a concentration chamber and a desalination chamber which are arranged in sequence from the anode chamber to the cathode chamber; the desalination chamber and the concentration chamber are connected through a monovalent or polyvalent selective anion exchange membrane; a solution to be concentrated is introduced into the desalination chamber in the electro-dehydration electrically driven membrane separation reaction system, a sodium chloride solution is introduced into the concentration chamber, a first electrolyte solution is introduced into the anode chamber, and a second electrolyte solution is introduced into the cathode chamber, and a low-salinity and high-concentration uranium solution is obtained through electrodialysis; the solution to be concentrated comprises uranium element and sodium chloride. Compared with the prior art, the present invention utilizes the advantages of the electro-dehydration electric-driven separation system to achieve the selective separation of ions of different valence states, and selectively separates sodium chloride from uranium in one step by optimizing the appropriate cation exchange membrane type and current density; and by utilizing electro-dehydration, high water migration can be obtained to enhance the enrichment effect of uranium; the method is simple to implement, has no harmful pollution to the environment, can utilize the characteristics of different ion exchange membranes to achieve the separation of single and multivalent ions, and can also cleverly utilize the defect of the ion exchange membrane that is not dense enough to turn disadvantages into advantages and reduce costs; at the same time, using the electric field force as the driving force, the separation effect is better, the enrichment efficiency is greatly improved, and the problems of the traditional physical adsorption method are avoided. Therefore, using the electro-dehydration electro-membrane reactor to separate and enrich uranium from seawater is a green, environmentally friendly and efficient method with important industrial application value.

[0037] Furthermore, the present invention couples the electric dehydration electric driven membrane separation reaction system and the electric driven membrane separation reaction system to perform multi-stage treatment, thereby achieving low salinity and high concentration of the uranium solution and obtaining a higher yield.

[0038] Experiments show that the uranium-containing solution obtained by multi-stage treatment by coupling the electric dehydration electric-driven membrane separation reaction system and the electric-driven membrane separation reaction system of the present invention has a uranium concentration of more than 22 ppm, an enrichment multiple of 7.5, and a yield of >80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of the structure of the electric dehydration and electric driven membrane separation reaction system provided by the present invention;

[0040] Figure 2 uranium enrichment curves of different cation exchange membrane desalination chambers in Example 1 of the present invention;

[0041] Figure 3 2 is a graph showing uranium enrichment in desalination chambers at different current densities in Example 2 of the present invention;

[0042] Figure 4 This is a graph showing the uranium enrichment curves of the three electrodialysis processes in Example 3 of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0044] The invention provides a method for separating and enriching uranium in seawater, comprising: providing an electro-dehydration electrically driven membrane separation reaction system; the electro-dehydration electrically driven membrane separation reaction system comprises an anode chamber, a reactor membrane stack and a cathode chamber which are arranged in sequence; the reactor membrane stack is connected with the anode chamber through a first cation exchange membrane; the reactor membrane stack is connected with the cathode chamber through a second cation exchange membrane; the reactor membrane stack comprises a reaction unit; the reaction unit comprises a concentration chamber and a desalination chamber which are arranged in sequence from the anode chamber to the cathode chamber; the desalination chamber and the concentration chamber are connected through a monovalent or polyvalent selective anion exchange membrane; a solution to be concentrated is introduced into the desalination chamber in the electro-dehydration electrically driven membrane separation reaction system, a sodium chloride solution is introduced into the concentration chamber, a first electrolyte solution is introduced into the anode chamber, and a second electrolyte solution is introduced into the cathode chamber, and a low-salinity and high-concentration uranium solution is obtained through electrodialysis; the solution to be concentrated comprises uranium element and sodium chloride.

[0045] The present invention has no particular limitation on the sources of all raw materials, and any raw materials available on the market can be used.

[0046] The present invention uses an electric dehydration and electric driven membrane separation reaction system to separate and enrich uranium in seawater. Figure 1 , Figure 1 The schematic diagram of the structure of the electro-dehydration electrically driven membrane separation reaction system provided by the present invention is as follows. The electro-dehydration electrically driven membrane separation system comprises an anode chamber, a reactor membrane stack and a cathode chamber which are arranged in sequence.

[0047] In the present invention, the anode chamber is connected to the positive electrode of the power supply through an anode plate; the anode plate can be any anode plate known to those skilled in the art without any special limitation, and corrosion-resistant titanium coated with ruthenium is preferred in the present invention.

[0048] The reactor membrane stack is connected to the anode chamber through a first cation exchange membrane; the first cation exchange membrane can be a cation exchange membrane well known to those skilled in the art without any special restrictions. In the present invention, it is preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd. or CM-2 produced by Japan Astom Company, and more preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd.

[0049] The reactor membrane stack includes a reaction unit; the reaction unit includes a concentration chamber and a desalination chamber arranged in sequence along the direction from the anode chamber to the cathode chamber; the desalination chamber and the concentration chamber are connected through a monovalent selective anion exchange membrane; in the present invention, the monovalent selective anion exchange membrane is preferably a dense ASA produced by Astom of Japan. The number of the reaction units is 1 or multiple without special restrictions, preferably 2 to 8 in the present invention, more preferably 4 to 5, which can be set by the number of reaction units; when the number of the reaction units is greater than or equal to 2, adjacent reaction units are connected through a cation exchange membrane, and the cation exchange membrane can be a cation exchange membrane well known to those skilled in the art, without special restrictions, preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd. or CM-2 produced by Astom of Japan, more preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd.

[0050] The other end of the reactor membrane stack is connected to the cathode chamber through a second cation exchange membrane; the second cation exchange membrane can be a cation exchange membrane well known to those skilled in the art, without any special restrictions. In the present invention, it is preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd. or CM-2 produced by Japan Astom Company, and more preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd.

[0051] The cathode chamber is preferably connected to the negative electrode of the power supply through a cathode plate; the cathode plate can be any cathode plate known to those skilled in the art without any special limitation. In the present invention, corrosion-resistant titanium coated with ruthenium is preferred.

[0052] In the present invention, the anode chamber in the electro-dehydration and electro-driven membrane separation system, the desalination chamber in the reactor membrane stack, the concentration chamber and the cathode chamber are preferably composed of a gasket with a flow channel and a grid; the above-mentioned first cation exchange membrane, the second cation exchange membrane, the cation exchange membrane and the monovalent selective anion exchange membrane are supported by a grid; in the present invention, it is preferably also included a sealing gasket to seal the edge of the membrane so that adjacent chambers are connected only through the membrane; the thickness of the gasket is preferably 0.5-1 mm, more preferably 0.8 mm.

[0053] A solution to be concentrated is introduced into a desalination chamber in an electric dehydration and electric driven membrane separation reaction system, a sodium chloride solution is introduced into a concentration chamber, a first electrolyte solution is introduced into an anode chamber, and a second electrolyte solution is introduced into a cathode chamber to perform electrodialysis; the solution to be concentrated comprises uranium and sodium chloride, and is preferably seawater in the present invention; the pH value of the solution to be concentrated is preferably 7.5 to 8.5, and more preferably 8; in the present invention, a sodium hydroxide solution is preferably used to adjust the pH value of the solution to be concentrated; the concentration of sodium chloride in the solution to be concentrated is the same as the concentration of sodium chloride in the sodium chloride solution; The concentrations of the electrolytes are preferably equal; the conductivity of the solution to be concentrated is preferably 30-50 mS / cm, more preferably 35-45 mS / cm, and more preferably 40 mS / cm; the volume of the solution to be concentrated in the desalination chamber is preferably greater than the volume of the sodium chloride solution in the concentration chamber; in the present invention, the volume of the solution to be concentrated is preferably 2-50 times, more preferably 2-30 times, more preferably 2-20 times, and most preferably 5-20 times the volume of the sodium chloride solution; the first electrolyte solution and the second electrolyte solution are each independently a sodium sulfate solution; The concentration of the sodium sulfate solution is preferably 0.01-1 mol / L, more preferably 0.1-1 mol / L, more preferably 0.2-0.8 mol / L, and most preferably 0.3-0.5 mol / L; the volume ratio of the solution to be concentrated to the first electrolyte solution is preferably (1-5):1, more preferably (2-3):1; the volume ratio of the solution to be concentrated to the second electrolyte solution is preferably (1-5):1, more preferably (2-3):1; in order to avoid the occurrence of concentration polarization, the solution to be concentrated, the sodium chloride solution, and the first electrolyte solution are preferably 1-5:1, more preferably (2-3):1. The linear velocity of the first electrolyte solution and the second electrolyte solution is preferably 3-10 cm / s, more preferably 3-8 cm / s, and even more preferably 3-5 cm / s. In the present invention, the electro-dehydration electrically driven membrane separation reaction system preferably also includes a peristaltic pump, which is used to control the flow rate of the solution to be concentrated, the sodium chloride solution, the first electrolyte solution and the second electrolyte solution. The electrodialysis is preferably carried out under direct current conditions, more preferably under constant current conditions. The current density of the electrodialysis is preferably 4-10 mA / cm 2 In the embodiment provided by the present invention, the current density of the electrodialysis is specifically 4 mA / cm 2, 6mA / cm 2 , 8mA / cm 2 or 10mA / cm 2 .

[0054] In the present invention, it is preferred that current is applied to perform electrodialysis until the conductivity of the solution in the desalination chamber reaches 5-10 mS / cm, and the electrodialysis is terminated to obtain a uranium solution with low salinity and high concentration.

[0055] The present invention utilizes the advantages of the electro-dehydration electric drive separation system to achieve the selective separation of ions of different valence states, and selectively separates sodium chloride from uranium in one step by optimizing the appropriate cation exchange membrane type and current density; and by utilizing electro-dehydration, high water migration can be obtained, thereby improving the enrichment effect of uranium; the method is simple to implement, has no harmful pollution to the environment, can utilize the characteristics of different ion exchange membranes to achieve the separation of single and multivalent ions, and can also cleverly utilize the defect that the ion exchange membrane is not dense enough, turning disadvantages into advantages and reducing costs; at the same time, using electric field force as the driving force, the separation effect is better, the enrichment efficiency is greatly improved, and the problems of the traditional physical adsorption method are avoided. Therefore, utilizing the electro-dehydration electro-membrane reactor to separate and enrich uranium from seawater is a green, environmentally friendly and efficient method with important industrial application value.

[0056] The present invention also provides another method for separating and enriching uranium in seawater, which adopts an electro-dehydration electrically driven membrane separation reaction system coupled with an ordinary electro-driven membrane separation reaction system for multi-stage treatment, including: providing an electro-dehydration electrically driven membrane separation reaction system and an electro-driven membrane separation reaction system; the electro-dehydration electrically driven membrane separation reaction system includes an anode chamber, a reactor membrane stack and a cathode chamber arranged in sequence; the reactor membrane stack is connected to the anode chamber through a first cation exchange membrane; the reactor membrane stack is connected to the cathode chamber through a second cation exchange membrane; the reactor membrane stack includes a reaction unit; the reaction unit includes a concentration chamber and a desalination chamber arranged in sequence along the direction from the anode chamber to the cathode chamber; the desalination chamber and the concentration chamber are connected through a mono-multivalent selective anion exchange membrane; the electro-driven membrane separation reaction system includes an electro-driven anode chamber, an electro-driven reactor membrane stack and an electro-driven cathode chamber arranged in sequence; the electro-driven reactor membrane stack is connected to the anode chamber through a third cation exchange membrane; the electro-driven reactor membrane stack is connected to the cathode chamber through a fourth cation exchange membrane The electric-driven reactor membrane stack includes an electric-driven reaction unit; the electric-driven reaction unit includes an electric-driven desalination chamber and an electric-driven concentrating chamber arranged in sequence along the direction from the electric-driven anode chamber to the electric-driven cathode chamber; the electric-driven desalination chamber and the electric-driven concentrating chamber are connected through an anion exchange membrane; the solution to be concentrated is introduced into the desalination chamber in the electric-driven membrane separation reaction system, the sodium chloride solution is introduced into the concentrating chamber, the first electrolyte solution is introduced into the anode chamber, and the second electrolyte solution is introduced into the cathode chamber to perform a first electrodialysis; the solution in the desalination chamber after the first electrodialysis is introduced into the electric-driven desalination chamber and the electric-driven concentrating chamber in the electric-driven membrane separation reaction system for a second electrodialysis; the solution in the concentrating chamber after the second electrodialysis is introduced into the desalination chamber in the electric-driven membrane separation reaction system, and at the same time, the sodium chloride solution is introduced into the concentrating chamber, the first electrolyte solution is introduced into the anode chamber, and the second electrolyte solution is introduced into the cathode chamber to perform a third electrodialysis to obtain a low-salinity and high-concentration uranium solution; the solution to be concentrated includes uranium element and sodium chloride.

[0057] The present invention has no special restrictions on the sources of all raw materials, and any raw materials available on the market can be used. The electro-dehydration electro-driven membrane separation reaction system is the same as described above, and will not be described in detail here.

[0058] The electrically driven membrane separation reaction system comprises an electrically driven anode chamber, an electrically driven reactor membrane stack and an electrically driven cathode chamber which are arranged in sequence; the anode chamber is connected to the positive electrode of the power supply via an anode plate; the anode plate can be an anode plate familiar to those skilled in the art without any special restrictions, and in the present invention, corrosion-resistant titanium coated with ruthenium is preferred.

[0059] The electrically driven reactor membrane stack is connected to the electrically driven anode chamber through a third cation exchange membrane; the third cation exchange membrane can be a cation exchange membrane well known to those skilled in the art without any special restrictions. In the present invention, it is preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd. or CM-2 produced by Japan Astom Corporation, and more preferably CM-2 produced by Japan Astom Corporation.

[0060] The electrically driven reactor membrane stack includes an electrically driven reaction unit; the electrically driven reaction unit includes an electrically driven desalination chamber and an electrically driven concentration chamber arranged in sequence along the direction from the electrically driven anode chamber to the electrically driven cathode chamber; the electrically driven desalination chamber and the electrically driven concentration chamber are connected through an anion exchange membrane; the anion exchange membrane is preferably AMX produced by Japan Astom Company; the number of the electrically driven reaction units can be 1 or more, and there is no special restriction. When the number of the electrically driven reaction units is greater than or equal to 2, adjacent electrically driven reaction units are connected through a cation exchange membrane, and the cation exchange membrane can be a cation exchange membrane well known to those skilled in the art, and there is no special restriction. In the present invention, preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd. or CM-2 produced by Japan Astom Company, more preferably CM-2 produced by Japan Astom Company.

[0061] The other end of the electrically driven reactor membrane stack is connected to the electrically driven cathode chamber through a fourth cation exchange membrane; the fourth cation exchange membrane can be a cation exchange membrane well known to those skilled in the art, without any special restrictions. In the present invention, it is preferably CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd. or CM-2 produced by Japan Astom Company, and more preferably CM-2 produced by Japan Astom Company.

[0062] The electrically driven cathode chamber is preferably connected to the negative electrode of the power supply via a cathode plate; the cathode plate can be any cathode plate known to those skilled in the art without any special limitation, and in the present invention, corrosion-resistant titanium coated with ruthenium is preferred.

[0063] The solution to be concentrated is introduced into the desalination chamber of the electro-dehydration electrically driven membrane separation reaction system, the sodium chloride solution is introduced into the concentration chamber, the first electrolyte solution is introduced into the anode chamber, and the second electrolyte solution is introduced into the cathode chamber to perform the first electrodialysis; wherein the solution to be concentrated, the sodium chloride solution, the first electrolyte solution and the second electrolyte solution are all as described above and will not be repeated here; the first electrodialysis is preferably performed under direct current conditions, more preferably under constant current conditions; the current density of the first electrodialysis is preferably 4-10 mA / cm2 In the embodiment provided by the present invention, the current density of the first electrodialysis is specifically 10mA / cm 2 In the present invention, it is preferred to apply current electrodialysis until the conductivity of the solution in the desalination chamber is 5 to 10 mS / cm, more preferably 8 to 10 mS / cm, and the first electrodialysis is completed.

[0064] The solution in the desalination chamber after the first electrodialysis is passed into the electrically driven desalination chamber and the electrically driven concentrating chamber in the electrically driven membrane separation reaction system for a second electrodialysis; the volume ratio of the solution in the electrically driven desalination chamber to the solution in the electrically driven concentrating chamber is preferably (2-10):1, more preferably (3-8):1, more preferably (4-6):1, and most preferably 5:1; during the second electrodialysis, the electrically driven anode chamber and the electrically driven cathode chamber in the electrically driven membrane separation reaction system are also respectively passed into the third electrolyte solution and the fourth electrolyte solution; the third electrolyte solution and the fourth electrolyte solution are each independently sodium sulfate solution; the sodium sulfate solution The concentration of the solution is preferably 0.01-1 mol / L, more preferably 0.1-1 mol / L, more preferably 0.2-0.8 mol / L, and most preferably 0.3-0.5 mol / L; the linear speeds of the solution in the electrically driven desalination chamber, the solution in the electrically driven concentration chamber, the third electrolyte solution, and the fourth electrolyte solution are each independently preferably 3-10 cm / s, more preferably 3-8 cm / s, and more preferably 3-5 cm / s; the second electrodialysis is preferably carried out under direct current conditions, more preferably under constant current conditions; the current density of the second electrodialysis is preferably 4-10 mA / cm 2 In the embodiment provided by the present invention, the current density of the second electrodialysis is specifically 5mA / cm 2 In the present invention, it is preferred to apply current electrodialysis until the conductivity of the solution in the electrically driven desalination chamber is 1 to 5 mS / cm, more preferably 2 to 3 mS / cm, and the second electrodialysis is completed.

[0065] The solution in the concentration chamber after the second electrodialysis is passed into the desalination chamber in the electro-dehydration electrically driven membrane separation reaction system, and at the same time, sodium chloride solution is passed into the concentration chamber, the first electrolyte solution is passed into the anode chamber, and the second electrolyte solution is passed into the cathode chamber, and the third electrodialysis is performed; in this step, the concentration of the sodium chloride solution is preferably equal to the concentration in the desalination chamber; the volume of the solution in the desalination chamber is preferably greater than the volume of the sodium chloride solution in the concentration chamber; in the present invention, the volume of the solution in the desalination chamber is preferably 2 to 50 times the volume of the sodium chloride solution, more preferably 2 to 30 times, more preferably 2 to 20 times, and most preferably 5 to 20 times; the first electrolyte solution and the second electrolyte solution are each independently sodium sulfate solution; the concentration of the sodium sulfate solution is preferably 0.01 to 1 mol / L, more preferably 0.1 to 1 mol / L / L, more preferably 0.2-0.8 mol / L, most preferably 0.3-0.5 mol / L; the volume ratio of the solution in the desalination chamber to the first electrolyte solution is preferably (1-5):1, more preferably (2-3):1; the volume ratio of the solution in the desalination chamber to the second electrolyte solution is preferably (1-5):1, more preferably (2-3):1; in order to avoid the occurrence of concentration polarization, the linear speed of the solution in the desalination chamber, the sodium chloride solution, the first electrolyte solution and the second electrolyte solution is independently preferably 3-10 cm / s, more preferably 3-8 cm / s, and more preferably 3-5 cm / s; the third electrodialysis is preferably carried out under direct current conditions, more preferably under constant current conditions; the current density of the third electrodialysis is preferably 4-10 mA / cm 2 In the embodiment provided by the present invention, the current density of the third electrodialysis is specifically 10mA / cm 2 In the present invention, it is preferred to apply current electrodialysis until the conductivity of the solution in the electrically driven desalination chamber is 5 to 10 mS / cm, more preferably 8 to 10 mS / cm, and the third electrodialysis is completed.

[0066] The present invention couples an electric dehydration electric drive membrane separation reaction system and an electric drive membrane separation reaction system to perform multi-stage treatment, thereby achieving low salinity and high concentration of a uranium solution and obtaining a higher yield.

[0067] In order to further illustrate the present invention, a method for separating and enriching uranium from seawater and an electrically driven membrane separation reaction system provided by the present invention are described in detail below in conjunction with embodiments.

[0068] The reagents used in the following examples are all commercially available.

[0069] In implementation, the following Figure 1The schematic diagram of the membrane stack of the electro-dehydration membrane reactor is shown. Anode plates and cathode plates are fixed on both sides of the reactor membrane stack. The plate material is corrosion-resistant titanium coated with ruthenium. The anode plate is connected to the positive pole of the power supply, and the cathode plate is connected to the negative pole of the power supply. The effective area of ​​a single membrane is 189cm 2 (9cm×21cm). The compartments between adjacent ion exchange membranes include a concentration chamber and a desalination chamber, which are composed of gaskets with flow channels and grids, and the thickness of the gasket is 0.8mm. The cation exchange membrane forms an anode chamber with the adjacent anode plate, and a cathode chamber with the adjacent cathode plate. The anode chamber and the cathode chamber are connected to store the anode chamber liquid, the desalination chamber stores simple simulated seawater containing uranium, and the concentration chamber stores sodium chloride solution of equal concentration. The number of repeating units of "concentration chamber-desalination chamber" composed of alternating common cation exchange membranes (CEM in the figure) and monovalent multivalent selective anion exchange membranes (ASA in the figure) is 5. The desalination chamber liquid processing capacity can be reasonably adjusted by setting the number of repeating units.

[0070] The method for separating and enriching uranium by using the above-mentioned electro-dehydration electro-membrane reactor is as follows:

[0071] First, a simple simulated seawater containing uranium (mainly sodium chloride solution) is introduced into the desalination chamber of the membrane stack of the electro-dehydration membrane reactor, a sodium chloride solution of equal concentration is introduced into the concentration chamber, and a strong electrolyte solution (sodium sulfate solution with a concentration of 0.01-1.0 mol / L) is introduced into the cathode chamber and the anode chamber respectively. The feed solution of each compartment is circulated by a peristaltic pump for 5-30 minutes to discharge the bubbles in the membrane stack. Then, direct current is applied to both ends of the reactor membrane stack. Under the action of direct current, the sodium ions in the desalination chamber migrate from the desalination chamber to the concentration chamber through the ordinary cation exchange membrane, while the chloride ions and tricarbonate uranyl anions are separated under the screening of the mono-multivalent selective anion exchange membrane. The chloride ions migrate to the concentration chamber, and the tricarbonate uranyl anions are retained in the desalination chamber. During the experiment, the ions migrate in the form of hydrated ions. At the same time, affected by the structure of the cation exchange membrane, current density, etc., the migration of water molecules is improved to varying degrees (from the desalination chamber to the concentration chamber), thereby improving the effect of electro-dehydration. Therefore, a uranium-containing solution with lower salinity and higher concentration can be obtained in the desalination chamber at the same time. During the experiment, the pH of the desalination chamber was always controlled at around 8, and the linear velocity of the solution flow in the anode chamber, cathode chamber, desalination chamber and concentration chamber was controlled at 3-10 cm / s by a peristaltic pump.

[0072] Example 1

[0073] 1000mL of simple simulated seawater containing uranium (25.6g / L sodium chloride, 193mg / L sodium bicarbonate and 3mg / L uranium standard solution, conductivity ~40mS / cm) was introduced into the desalination chamber of the electro-dehydration membrane reactor, 200mL of sodium chloride solution of equal concentration was introduced into the concentration chamber, the anode chamber and the cathode chamber were connected in series, and 500mL of 0.3mol / L Na2SO4 aqueous solution was introduced as a strong electrolyte solution. During the experiment, the common cation exchange membranes were selected as CJMC-5 produced by Hefei Kejia Polymer Materials Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd. and CM-2 produced by Astom, Japan, respectively. The monovalent and multivalent selective anion exchange membranes were selected as ASA produced by Astom, Japan. The linear velocity of each solution flowing in the membrane stack was 3cm / s, constant current operation, and the current density was 10mA / cm 2 , the current is set to 1.89A, and the voltage upper limit is set to 30V.

[0074] The experiment was stopped when the conductivity of the desalination chamber dropped to 5mS / cm. The different cation exchange membranes selected for the electro-dehydration membrane reactor resulted in different degrees of uranium concentration increase due to different electro-dehydration effects. The uranium enrichment curves of the desalination chambers with different cation exchange membranes are shown in Figure 2. Figure 2 As shown. Figure 2 It can be seen that the uranium enrichment factors measured in the desalination chamber using CJMC-5, TWEDC and CM-2 are 1.24, 1.14 and 1.06 respectively. This shows that the electro-dehydration electro-membrane reactor can significantly reduce the salinity in the desalination chamber while increasing the uranium concentration, thereby achieving the separation and enrichment of uranium from seawater.

[0075] Example 2

[0076] 1000mL of simple simulated seawater containing uranium (25.6g / L sodium chloride, 193mg / L sodium bicarbonate and 3mg / L uranium standard solution, conductivity ~40mS / cm) was introduced into the desalination chamber of the electro-dehydration membrane reactor, 200mL of sodium chloride solution of equal concentration was introduced into the concentration chamber, the anode chamber and the cathode chamber were connected in series, and 500mL of 0.3mol / L Na2SO4 aqueous solution was introduced as a strong electrolyte solution. During the experiment, the common cation exchange membrane was selected as CJMC-5 produced by Hefei Kejia Polymer Materials Technology Co., Ltd., and the mono-multivalent selective anion exchange membrane was selected as ASA produced by Astom Company of Japan. The linear velocity of each solution flowing in the membrane stack was 3cm / s, and the constant current operation was performed with a current density of 4, 6, 8, and 10mA / cm 2 The current settings are 0.76A, 1.13A, 1.51A, and 1.89A respectively, and the voltage upper limit is set to 30V.

[0077] The experiment was stopped when the conductivity of the desalination chamber dropped to 5mS / cm. The different current densities applied to the electro-dehydration membrane reactor resulted in different degrees of uranium concentration increase due to different electro-dehydration effects. The uranium enrichment curves of the desalination chambers with different current densities are shown in Figure 2. Figure 3 As shown. Figure 3 It can be seen that the applied current density is 4, 6, 8 and 10 mA / cm 2 The uranium enrichment factors measured in the desalination chamber were 1.49, 1.36, 1.29 and 1.24 respectively. This shows that the electro-dehydration electro-membrane reactor can significantly reduce the salinity in the desalination chamber while increasing the uranium concentration, thereby achieving the separation and enrichment of uranium from seawater.

[0078] Example 3

[0079] In the first step, 4000mL of simple simulated seawater containing uranium (25.6g / L sodium chloride, 193mg / L sodium bicarbonate and 3mg / L uranium standard solution, conductivity ~40mS / cm) was introduced into the desalination chamber of the electro-dehydration membrane reactor, and 200mL of sodium chloride solution of equal concentration was introduced into the concentration chamber. The anode chamber and the cathode chamber were connected in series, and 500mL of 0.3mol / L Na2SO4 aqueous solution was introduced as a strong electrolyte solution. During the experiment, the common cation exchange membrane was selected as CJMC-5 produced by Hefei Kejia Polymer Materials Technology Co., Ltd., and the monovalent multivalent selective anion exchange membrane was ASA produced by Astom Corporation of Japan. The linear velocity of each solution flowing in the membrane stack was 3cm / s, and the constant current operation was performed with a current density of 10mA / cm 2 , the current was set to 1.89 A, and the upper voltage limit was set to 30 V. The experiment was stopped when the conductivity of the desalination chamber dropped to 10 mS / cm.

[0080] In the second step, the feed liquid of the desalination chamber is obtained through the electro-dehydration membrane reactor, and is divided according to a certain volume ratio (desalination chamber: concentration chamber = 5:1) as the initial feed liquid of the desalination chamber and the concentration chamber, and enters the common membrane reactor. Different volumes of feed liquid are respectively introduced into the desalination chamber and the concentration chamber in the common membrane reactor (the feed liquid is the feed liquid of the desalination chamber after the first step of the electro-dehydration membrane reactor), the anode chamber and the cathode chamber are connected in series, and 500mL of 0.3mol / L Na2SO4 aqueous solution is introduced as a strong electrolyte. During the experiment, the common cation exchange membrane was CM-2 produced by Astom, Japan, and the common anion exchange membrane was AMX produced by Astom, Japan. The linear velocity of each solution flowing in the membrane stack was 3cm / s, and the constant current operation was performed with a current density of 5mA / cm 2 , the current was set to 0.95 A, and the upper voltage limit was set to 30 V. The experiment was stopped when the conductivity of the desalination chamber dropped to 2 mS / cm.

[0081] The third step is to obtain the feed liquid of the concentration chamber through the ordinary electromembrane reactor, and use it as the initial feed liquid of the desalination chamber for the experiment. The feed liquid is introduced into the desalination chamber of the membrane stack of the electrodehydration electromembrane reactor (the feed liquid is the feed liquid of the concentration chamber after the ordinary electromembrane reaction treatment in the second step), and 200mL of sodium chloride solution with the same concentration as the desalination chamber is introduced into the concentration chamber. The anode chamber and the cathode chamber are connected in series, and 500mL of 0.3mol / L Na2SO4 aqueous solution is introduced as a strong electrolyte solution. During the experiment, the ordinary cation exchange membrane was selected as CJMC-5 produced by Hefei Kejia Polymer Materials Technology Co., Ltd., and the monovalent multivalent selective anion exchange membrane was ASA produced by Astom Corporation of Japan. The linear velocity of each solution flowing in the membrane stack was 3cm / s, and the constant current operation was performed with a current density of 10mA / cm 2 , the current was set to 1.89 A, and the upper voltage limit was set to 30 V. The experiment was stopped when the conductivity of the desalination chamber dropped to 10 mS / cm.

[0082] The three-stage electrodialysis uranium enrichment curve is as follows Figure 4 As shown. Figure 4 It can be seen that after multi-stage treatment by coupling the electro-dehydration membrane reactor and the ordinary membrane reactor, the uranium concentration in the feed liquid is greatly increased, and the final uranium concentration in the desalination chamber can reach more than 22 ppm, the enrichment factor reaches 7.5, and the yield is >80%. This shows that multi-stage treatment by coupling the electro-dehydration membrane reactor and the ordinary membrane reactor can greatly reduce the salinity in the desalination chamber and greatly increase the uranium concentration, thereby realizing the separation and enrichment of uranium from seawater using the electro-dehydration membrane reactor.

[0083] As can be seen from the above, the present invention provides a method for separating and enriching uranium from seawater using an electro-dehydration membrane reactor, which uses a single multivalent selective anion exchange membrane and a loosely structured cation exchange membrane, and is assisted by an electro-dehydration membrane reactor and a common membrane reactor for coupling to perform multi-stage treatment, successfully achieving the separation and enrichment of uranium (the uranium enrichment multiple is 7.5, and the yield is >80%). In addition, the present invention is simple to implement and has no harmful danger to the environment; the characteristics of the ion exchange membrane are used to achieve the separation of single and multivalent ions, and the defect of the ion exchange membrane being not dense enough is cleverly used to turn disadvantages into advantages and reduce costs; the electric field force is used as the driving force to ensure the separation effect while improving the enrichment efficiency, solving the disadvantages of the traditional physical adsorption method. Therefore, the use of an electro-dehydration membrane reactor to separate and enrich uranium from seawater is a green, environmentally friendly, and efficient method with important industrial application value.

Claims

1. A method for separating and enriching uranium in seawater, characterized in that: include: An electro-dehydration electrically driven membrane separation reaction system is provided; the electro-dehydration electrically driven membrane separation reaction system comprises an anode chamber, a reactor membrane stack and a cathode chamber arranged in sequence; The reactor membrane stack is connected to the anode chamber through a first cation exchange membrane; The reactor membrane stack is connected to the cathode chamber through a second cation exchange membrane; The reactor membrane stack comprises a reaction unit; the reaction unit comprises a concentration chamber and a desalination chamber arranged in sequence along the direction from the anode chamber to the cathode chamber; the desalination chamber and the concentration chamber are connected through a monovalent or polyvalent selective anion exchange membrane; the number of the reaction units is greater than or equal to 2; adjacent reaction units are connected through a cation exchange membrane; A solution to be concentrated is introduced into a desalination chamber in an electric dehydration and electric driven membrane separation reaction system, a sodium chloride solution is introduced into a concentration chamber, a first electrolyte solution is introduced into an anode chamber, and a second electrolyte solution is introduced into a cathode chamber, and a low-salinity and high-concentration uranium solution is obtained by electrodialysis; The solution to be concentrated includes uranium element and sodium chloride; The pH value of the solution to be concentrated is 7.5 to 8.5; The first electrolyte solution and the second electrolyte solution are each independently a sodium sulfate solution; the concentration of the sodium sulfate solution is 0.01 to 1 mol / L; The first cation exchange membrane and the second cation exchange membrane are independently selected from CJMC-5 produced by Hefei Kejia Polymer Material Technology Co., Ltd., TWEDC produced by Shandong Tianwei Membrane Technology Co., Ltd., or CM-2 produced by Japan Astom Company; The monovalent and multivalent selective anion exchange membrane is selected from the dense ASA produced by Astom Company of Japan; The current density of the electrodialysis is 4-10 mA / cm 2 .

2. The method according to claim 1, characterized in that The concentration of sodium chloride in the solution to be concentrated is equal to the concentration of sodium chloride in the sodium chloride solution.

3. The method according to claim 1, characterized in that The volume of the solution to be concentrated in the desalination chamber is greater than the volume of the sodium chloride solution in the concentration chamber.

4. The method according to claim 1, characterized in that: The linear speeds of the solution to be concentrated, the sodium chloride solution, the first electrolyte solution and the second electrolyte solution are independently 3 to 10 cm / s.

Images