A separation membrane for cesium in solution and its preparation method and application

Abstract

The present invention provides a membrane for separating cesium from solution, its preparation method, and its application, belonging to the field of membrane separation technology. This invention utilizes an ion exchange-deposition growth method to grow a layer of Prussian blue analog particles with specific permeability to cesium ions on the surface of a cation exchange membrane to form the separation membrane. Combining the advantages of high selectivity and continuous operation of membrane separation, this method has been developed to continuously separate and enrich cesium from water under electrical drive. This method achieves industrial continuous operation while ensuring efficient and selective separation of cesium ions in water.

Description

Technical Field

[0001] The present invention relates to the field of membrane separation technology, and more particularly to a cesium separation membrane in a solution, a preparation method thereof, and an application thereof. Background Art

[0002] Cesium is an important key metal, with applications primarily in the electronics, energy, petroleum, and medical industries. Whether extracted from ore, salt lakes, or seawater, cesium must pass through a solution state, requiring separation. Furthermore, cesium-related electronics and chemical companies may discharge large amounts of cesium-containing wastewater during production, requiring separation and enrichment. Cesium-containing wastewater generated during treatment in cesium-contaminated areas also requires separation.

[0003] After decades of development, research on removing cesium ions from wastewater has been relatively extensive, among which membrane separation technology has been widely studied due to its high selectivity and good application prospects. Membrane separation has the advantages of simple operation and no secondary pollution, but the performance and cost of membrane materials are the key issues restricting its development. Among them, the main research directions of the technology of using membrane separation to treat wastewater containing cesium, strontium, lanthanum and zirconium are membrane adsorption materials, filter membranes, liquid membranes, reverse osmosis membranes, and MD membranes. Zhaoyong Ye et al. successfully prepared a new type of GO / PB modified nanofiltration membrane (PB content is 5wt%, GO content is 0.1wt%, PEG content is 15wt%) by combining graphene oxide and Prussian blue. The nanofiltration membrane has the advantages of both membrane separation and adsorption, and the water flux is 24.79L / (m 2 h), Cs in wastewater + and Sr 2+ With ultra-high removal rates (99.5% and 97.5% respectively). Hyung-Ju Kim et al. studied the ability of nanofiltration (NF) membrane and reverse osmosis (RO) membrane to remove radionuclides (cesium, strontium and cobalt) from solution. In the osmotic simulation of seawater, the nanofiltration membrane showed a removal rate of 160 to 210 L·(m -2 ·h -1 ) high flux, while the reverse osmosis (RO) membrane showed 13 to 22 L·(m -2 ·h -1 ) has a low flux. However, the reverse osmosis membrane is more effective in removing radionuclides (cesium, strontium and cobalt) in dilute aqueous solutions. Its removal rate for single components exceeds 93%, and the removal rate for mixed radionuclides is even higher (>98%). Xi Zhang et al. used dopamine-modified bacterial cellulose (BC) as a template and designed a cesium ion imprinted composite membrane (I-DBC) through sol-gel surface imprinting technology. The results showed that the I-DBC composite membrane is more consistent with the Langmuir model and mainly adsorbs Cs(I) in the form of chemical monolayer adsorption. The maximum adsorption capacity under optimal conditions is 50.016 mg·g-1 In low-concentration wastewater, the maximum adsorption capacity of I-DBC is 4.093 mg·g -1 .

[0004] Because cesium is an alkali metal that is easily soluble in water, separating it from wastewater is difficult. Traditional pressure membranes have low selectivity for cesium, while membrane adsorption methods have low adsorption capacity, making it difficult to achieve the goal of separating and enriching cesium ions from solutions. Therefore, the efficient separation of cesium ions from contaminated water bodies remains an urgent task. The present invention combines the high selectivity of ion exchange membranes with the research on the separation of cesium from solutions under electrical drive, which can achieve continuous separation of cesium from solutions. Summary of the Invention

[0005] To address the aforementioned technical issues, the present invention provides a cesium separation membrane, its preparation method, and its application. A thin layer of a Prussian blue analogue, specifically selective for cesium, is grown on the surface of a cation exchange membrane via an ion exchange-deposition growth method. During the separation and enrichment of cesium from the solution, the Prussian blue acts as an ion channel for cesium, achieving efficient separation and enrichment.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A cesium separation membrane in a solution is composed of a cation exchange membrane and Prussian blue analogue particles having exclusive permeability to cesium ions grown on one surface of the cation exchange membrane.

[0008] Furthermore, the cation exchange membrane is a sulfonic acid cation exchange membrane.

[0009] Furthermore, the chemical formula of the Prussian blue analogue is A x M Ay [M B (CN)6] Z -nH2O, where 0≤x≤2, 1≤y≤4, 1≤z≤3, A represents an alkali metal, M A and M B It is any one of Fe, Cr, Ti, Ni, Co, Mn, Cu, and Zn. The value of n is not limited.

[0010] The above-mentioned method for preparing the separation membrane comprises the following steps:

[0011] S1, M Am Y n Solution and A x [M B (CN)6] solution was placed on both sides of the electrolytic cell, and the middle of the electrolytic cell was separated by a cation exchange membrane. Am Y n With Ax [M B The molar ratio of (CN)6] is 1 to 3:1, and the solution concentration is controlled at 0.01 mol / L to 1 mol / L;

[0012] Among them, M A =Fe, Cr, Ti, Ni, Co, Mn, Cu or Zn, Y = Cl - , SO2-4 or NO-3, F - ;A=K, Na or Li, X=3 or 4; M B =Fe, Cr, Ti, Ni, Co, Mn, Cu or Zn;

[0013] S2, using the current or concentration difference to make M A Ions pass through the cation exchange membrane and interact with A on the other side of the cation exchange membrane. x [M B (CN)6] reaction deposition growth forms a layer of Prussian blue analog particles that are exclusively permeable to cesium ions, thereby obtaining a separation membrane.

[0014] Furthermore, the concentration difference is made to A Ions pass through the cation exchange membrane as follows: Am Y n The end where the solution is located is set as the anode chamber, and the anode is inserted; A x [M B The cathode chamber is set at one end where the (CN)6] solution is located, and the cathode is inserted. The temperature of the electrolysis system is controlled to be maintained at 25℃~60℃, and the current density is 0.5~50A / m 2 .

[0015] In this application, the concentration difference is used to make M A In the process of ions passing through the cation exchange membrane, there is no restriction on the concentration difference, and M is required. A Ions can pass through the cation exchange membrane to the other side.

[0016] Furthermore, the separation membrane has a thickness of 50 to 1000 μm.

[0017] A method for efficiently separating and enriching cesium in a solution comprises using the above-mentioned separation membrane as a diaphragm, placing a solution to be treated in the anode chamber, and a blank solution to be enriched in the cathode chamber. Under the action of an electric current, cesium ions are enriched in the cathode chamber through the separation membrane from the anode chamber.

[0018] Further, the following steps are included:

[0019] S1. Construction of separation system:

[0020] The Prussian blue composite membrane is used as the diaphragm, the anode chamber is filled with the solution to be treated, and the cathode chamber is filled with the blank solution to be enriched;

[0021] S2. Separation of cesium ions in solution:

[0022] The electric field of the solution is controlled by the working electrode, so that cesium ions pass through the Prussian blue membrane and are enriched in the cathode chamber.

[0023] Furthermore, in the working electrode, the anode and the cathode can be inert electrodes or soluble electrodes.

[0024] Furthermore, the solution in the cathode chamber is an acidic or neutral solution (pH = -0.5 to 7), the solution in the anode chamber is an acidic or neutral solution (pH = -0.5 to 7), the electrolysis voltage is 0.5 to 10 V, and the current density is 0.5 to 50 A / m 2 .

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] The present invention uses an ion exchange-deposition growth method to grow a layer of Prussian blue-like particles on the surface of a cation exchange membrane, forming a separation membrane with exclusive permeability to cesium ions. This separation membrane exhibits excellent selectivity for cesium, is simple to prepare, and exhibits strong anti-interference capabilities. Combined with an electric field, it can rapidly separate and enrich cesium ions from a solution. The separation membrane provided by the present invention is capable of continuously separating cesium ions from a solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the cesium separation device by diaphragm electrolysis (A) and schematic diagram of the separation membrane cross section (B).

[0028] Figure 2 SEM-EDS images of both sides of the separation membrane; a is the contact Figure 1 The surface of the membrane with the solution on the a side and the contact surface on the b side Figure 1 The membrane surface of the solution on the b side. DETAILED DESCRIPTION

[0029] In order to facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed manner below in conjunction with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0030] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0032] Example 1

[0033] Prepare 0.1 mol / L FeSO4 solution and 0.1 mol / L K3[Fe(CN)6] solution respectively. Place the FeSO4 solution in the anode chamber and the K3[Fe(CN)6] in the cathode chamber. Use a sulfonic acid cation exchange membrane to separate the two sides of the electrolytic cell. Control the solution temperature at 25°C and the current density at 0.5A / m 2 A Prussian blue analogue formed on the cathode side of the cation exchange membrane. After 10 minutes, the membrane was removed and stored in deionized water. The membrane thickness was 250 μm, designated M1. The membrane was then used as a diaphragm in an electrolysis device to treat simulated cesium-containing wastewater.

[0034] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+ , the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 After 10 hours of electrolysis, the removal rate of cesium was calculated to be 76.3%, and Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =20.3, f Cs / La =69.1, f Cs / Zr =85.1.

[0035] Example 2

[0036] Prepare 0.1 mol / L CuSO4 solution and 0.1 mol / L K3[Fe(CN)6] solution respectively. Place the CuSO4 solution in the anode chamber and the K3[Fe(CN)6] in the cathode chamber. Use a sulfonic acid cation exchange membrane to separate the two sides of the electrolytic cell. Control the solution temperature at 25°C and the current density at 0.5A / m 2 A Prussian blue analogue formed on the cathode side of the cation exchange membrane. After 10 minutes, the membrane was removed and stored in deionized water. The membrane thickness was 250 μm, recorded as M2. The membrane was then used as a diaphragm in an electrolysis device to treat simulated cesium-containing wastewater.

[0037] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+, the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 After 10 hours of electrolysis, the removal rate of cesium was calculated to be 82.4%, and Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =30.5, f Cs / La =70.9, f Cs / Zr =90.6.

[0038] Example 3

[0039] A 0.1 mol / L CuSO4 solution and a 0.1 mol / L K3[Co(CN)6] solution were prepared, respectively. The CuSO4 solution was placed in the anode chamber and the K3[Co(CN)6] solution was placed in the cathode chamber. A sulfonic acid cation exchange membrane was used to separate the two sides of the electrolytic cell. The solution temperature was controlled at 30°C and the current was controlled at 0.001A. A Prussian blue analog formed on the surface of the cation exchange membrane located in the cathode chamber. After 10 minutes, the separation membrane was removed and stored in deionized water. The membrane thickness was 250 μm, recorded as M3. The separation membrane was then used as a diaphragm in an electrolysis device to treat simulated cesium-containing wastewater.

[0040] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+ , the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 , electrolysis for 10h, the removal rate of cesium was calculated to be 80.1%, Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =25.4, f Cs / La =64.9, f Cs / Zr =84.3.

[0041] Example 4

[0042] Prepare 0.1 mol / L CoSO4 solution and 0.1 mol / L K4[Fe(CN)6] solution respectively. Place the CoSO4 solution in the anode chamber and the K4[Fe(CN)6] in the cathode chamber. Use a sulfonic acid cation exchange membrane to separate the two sides of the electrolytic cell. Control the solution temperature at 60°C and the current density at 0.5A / m 2A Prussian blue analogue formed on the cathode side of the cation exchange membrane. After 10 minutes, the membrane was removed and stored in deionized water. The membrane thickness was 250 μm, designated M4. The membrane was then used as a diaphragm in an electrolysis device to treat simulated cesium-containing wastewater.

[0043] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+ , the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 After 10 hours of electrolysis, the removal rate of cesium was calculated to be 79.5%, and Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =28.0, f Cs / La =56.5, f Cs / Zr =85.5.

[0044] Example 5

[0045] Prepare 0.1 mol / L CuSO4 solution and 0.1 mol / L K3[Fe(CN)6] solution respectively. Place the CuSO4 solution in the anode chamber and the K3[Fe(CN)6] in the cathode chamber. Use a sulfonic acid cation exchange membrane to separate the two sides of the electrolytic cell. Control the solution temperature at 60°C and the current density at 5A / m 2 A Prussian blue analogue formed on the cathode side of the cation exchange membrane. After 10 minutes, the membrane was removed and stored in deionized water. The membrane thickness was 300 μm, designated M5. The membrane was then used as a diaphragm in an electrolysis device to treat simulated cesium-containing wastewater.

[0046] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+ , the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 After 10 hours of electrolysis, the removal rate of cesium was calculated to be 95.7%, and Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =119.7, f Cs / La =172.0, f Cs / Zr=336.8.

[0047] Example 6

[0048] Prepare 0.1 mol / L NiSO4 solution and 0.1 mol / L K3[Fe(CN)6] solution respectively. Place the NiSO4 solution in the anode chamber and the K3[Fe(CN)6] in the cathode chamber. Use a sulfonic acid cation exchange membrane to separate the two sides of the electrolytic cell. Control the solution temperature at 40°C and the current density at 50A / m 2 A Prussian blue analogue formed on the cathode side of the cation exchange membrane. After 30 minutes, the membrane was removed and stored in deionized water. The membrane thickness was 400 μm, designated M6. The membrane was then used as a diaphragm in an electrolysis device to treat simulated cesium-containing wastewater.

[0049] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+ , the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 After 10 hours of electrolysis, the removal rate of cesium was calculated to be 99.8%, and Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =152.2, f Cs / La =247.4, f Cs / Zr =435.9.

[0050] Example 7

[0051] A 0.1 mol / L CuSO₄ solution and a 0.1 mol / L K₃[Fe(CN)₆] solution were prepared, respectively. The CuSO₄ solution was placed in the anode chamber, and the K₃[Fe(CN)₆] solution was placed in the cathode chamber. A sulfonic acid cation exchange membrane was used to separate the two sides of the electrolytic cell. The solution temperature was controlled at 40°C, and the movement of Cu ions was driven solely by the concentration difference. After 120 minutes, the membrane was removed and stored in deionized water. The membrane thickness was 280 μm, designated M7. The separation membrane was then used as a diaphragm in an electrolysis device to treat simulated cesium-containing wastewater.

[0052] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+, the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 After 10 hours of electrolysis, the removal rate of cesium was calculated to be 90.8%, and Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =72.2, f Cs / La =127.4, f Cs / Zr =235.9.

[0053] Comparative Example 1

[0054] An unmodified sulfonic acid cation exchange membrane with a thickness of 200 μm, designated as M8, was used to treat simulated cesium-containing wastewater using an electrolysis device.

[0055] In the electrolytic cell, 1 L of 1 g / L CsNO3 solution (pH = 2) was placed in the anode chamber, and the coexisting ions included 1 g / L Sr 2+ 、La 3+ 、Zr 4+ , the cathode chamber uses 0.01mol / L nitric acid solution. Inert electrodes are inserted on both sides and the current density is controlled to 10A / m 2 , electrolysis for 10h, the removal rate of cesium was calculated to be 22.1%, Cs + With Sr 2+ 、La 3+ 、Zr 4+ The separation factor f Cs / Sr =0.9, f Cs / La =1.1, f Cs / Zr =1.5.

[0056] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a cesium separation membrane in a solution, characterized in that: The steps include: S1, M Am Y n Solution and A x [M B (CN)6] solution was placed on both sides of the electrolytic cell, and the middle of the electrolytic cell was separated by a cation exchange membrane. Am Y n With A x [M B The molar ratio of (CN)6] is 1~3:1, and the solution concentration is controlled at 0.01mol / L~1mol / L; Among them, M A =Fe, Cr, Ti, Ni, Co, Mn, Cu or Zn, Y=Cl - 、SO4 2- or NO3 - 、F - ;A=K, Na or Li, X=3 or 4; M B =Fe, Cr, Ti, Ni, Co, Mn, Cu or Zn; S2, using the current or concentration difference to make M A Ions pass through the cation exchange membrane and interact with A on the other side of the cation exchange membrane. x [M B (CN)6] reaction deposition growth forms a layer of Prussian blue analog particles that are exclusively permeable to cesium ions, thereby obtaining a separation membrane.

2. The preparation method according to claim 1, characterized in that The specific use of current is: Am Y n The end where the solution is located is set as the anode chamber, and the anode is inserted; A x [M B The cathode chamber is set at one end where the (CN)6] solution is located, and the cathode is inserted. The temperature of the electrolysis system is controlled to be maintained at 25℃~60℃, and the current density is 0.5~50 A / m 2 .

3. The preparation method according to claim 1, characterized in that The cation exchange membrane is a sulfonic acid type cation exchange membrane.

4. The preparation method according to claim 1, characterized in that The thickness of the separation membrane is 50-1000 μm.

5. A method for separating and enriching cesium in a solution, characterized in that: The separation membrane prepared by the preparation method according to any one of claims 1 to 4 is used as a diaphragm, the anode chamber is placed in the solution to be treated, the cathode chamber is the blank solution to be enriched, and under the action of current, cesium ions are enriched from the anode chamber through the separation membrane in the cathode chamber.

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