Method for separating and enriching cesium in solution

Abstract

The invention provides a method for separating and enriching cesium in a solution, and belongs to the technical field of hydrometallurgy. Under the action of an electric field, cesium ions are enriched through the Prussian blue diaphragm with selectivity. The method for continuously separating and enriching cesium from the water body under electric driving is developed by referring to a diaphragm electrolysis method and combining the advantages of high selectivity and continuous operation of membrane separation. And efficient selective separation of cesium ions in a water body is ensured while industrial continuous operation is realized.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and more specifically to a method for separating and enriching cesium in a solution. Background Art

[0002] Cesium is an important key metal, and its application areas mainly include the electronics industry, energy field, petroleum industry, and medical treatment. Whether cesium is extracted from ore, salt lake, or seawater, it needs to go through a solution state, and the cesium in the solution needs to be separated. In addition, electronic and chemical companies related to cesium may discharge a large amount of cesium-containing wastewater during the production process, and this part of cesium must also be separated and enriched. The cesium-containing wastewater generated during the treatment process in cesium-contaminated areas also needs to be separated. Therefore, the development of a treatment solution system to separate cesium is a pollution problem that needs to be solved urgently.

[0003] At present, the treatment methods for removing cesium from wastewater can be summarized as follows: chemical precipitation, solvent extraction, membrane separation, adsorption, etc. Membrane separation technology is a method of selectively separating particles of different sizes under multiple driving forces, which is called membrane filtration (MF) and membrane distillation (MD) according to the pressure gradient and temperature gradient, respectively. The application of membrane separation technology in cesium separation has the advantages of large decontamination factor, but the selectivity of membrane separation for cesium is not enough at this stage. The present invention develops a highly efficient and selective cesium separation membrane with the help of the exclusive selectivity of specific Prussian blue for cesium ions.

[0004] Since cesium ions have low electronegativity, large ion radius, easy migration, and are similar to Na and K ions, selective separation is difficult. In order to achieve high separation coefficients and purification depths, it is necessary to specially design efficient separation membranes and implement them under certain operating methods. In addition, there are a large number of ion interferences in the solution to be treated, which leads to reduced selectivity for cesium. Therefore, efficient separation of cesium ions from contaminated water bodies is still a task that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for efficiently separating and enriching cesium in a solution, which utilizes the special cubic crystal structure in the Prussian blue analog film to construct an ion channel, and develops a method for continuously separating and enriching cesium from water under electrical drive by controlling the size and direction of the electric field in the solution. Under the action of the electric field, various ions in the solution are directed to move, and when the cations migrate toward a specific Prussian blue analog film, the cesium ions can pass through due to the special structure of the membrane surface, while other cations in the solution are intercepted, thereby achieving efficient separation and enrichment of cesium.

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

[0007] The invention discloses a method for efficiently separating and enriching cesium in a solution. Under the action of an electric field, cesium ions are enriched through a selective Prussian blue analog membrane.

[0008] Further, the following steps are included:

[0009] S1. Synthesis of Prussian blue analog film:

[0010] The synthetic chemical formula is A x M Ay [M B (CN)6] Z -nH2O Prussian blue analogue, reacting with an organic binder through hydrothermal reaction to form a film casting solution, and the film casting solution is made into a Prussian blue analogue film;

[0011] Where 0≤x≤2, 1≤y≤4, 1≤z≤3, A represents an alkali metal, M A and M B Any one of Fe, Cr, Ti, Ni, Co, Mn, Cu and Zn;

[0012] S2. Construction of separation system:

[0013] A Prussian blue analog membrane is used as a 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;

[0014] S3. Separation of cesium ions in solution:

[0015] The electric field of the solution is controlled by the working electrode, so that cesium ions pass through the Prussian blue analog membrane and are enriched in the cathode chamber.

[0016] The invention firstly synthesizes a Prussian blue analogue with exclusive selectivity for cesium ions, takes the Prussian blue as a precursor, synthesizes a composite membrane containing a large number of cesium ion channels, controls the size and direction of the electric field in the solution through electrodes, and makes the ions in the solution move in a directional manner. When the cations migrate toward the specific Prussian blue analogue membrane, the cesium ions can pass through due to the special structure of the membrane surface, while other cations in the solution are retained, thereby realizing efficient separation and enrichment of cesium.

[0017] Furthermore, the chemical composition of Prussian blue is A x M Ay [M B (CN)6] Z -nH2O (e.g., Fe4[Fe(CN)6]3, Cu2[Fe(CN)6], KNi[Co(CN)6]), where 0≤x≤2, 1≤y≤4, 1≤z≤3, A represents an alkali metal (Li, K, Na, etc.), M A and M BIt is any one of Fe, Cr, Ti, Ni, Co, Mn, Cu, and Zn.

[0018] Further, the raw material for synthesizing Prussian blue is Am Y n and A x [M B (CN)6]; where 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.

[0019] Furthermore, M Am Y n : A x [M B The molar ratio of (CN)6] is 1 to 3:1, and the solution concentration is 0.01 mol / L to 1 mol / L.

[0020] Furthermore, the organic binder includes any one or more of polystyrene, polyamide, sulfonated polysulfone, polyvinylidene fluoride, polyvinyl chloride, polypropylene, polysulfone, and polytetrafluoroethylene.

[0021] Furthermore, the temperature of the hydrothermal reaction is 40-90° C., and the rotation speed is 100-600 r / min.

[0022] Furthermore, the casting solution is subjected to spin coating, dip coating, phase inversion or hot pressing to prepare a Prussian blue analog film.

[0023] Furthermore, in the working electrode, the anode can be an inert electrode or a soluble electrode, and the cathode can be a graphite electrode, a copper electrode, a platinum electrode, etc.

[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 0.1 to 100 A / m 2 .

[0025] Furthermore, the specific Prussian blue analog film has a thickness of 50 to 1000 μm.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] The present invention utilizes the selectivity of the Prussian blue analog membrane for cesium ions, and combines the electric field to enable the cesium ions in the solution to enter the cathode chamber through the Prussian blue analog membrane for enrichment, thereby achieving efficient enrichment of cesium ions in the water body. The present invention draws on the method of diaphragm electrolysis, combines the advantages of high selectivity and continuous operation of membrane separation, and develops a method for continuous separation and enrichment of cesium from water under electric drive. While achieving industrial continuous operation, it ensures efficient and selective separation of cesium ions in water, providing a new route for the treatment of cesium pollution in water bodies and hydrometallurgical processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the SEM image of the Prussian blue analog film. DETAILED DESCRIPTION

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

[0030] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional 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] A method for separating and enriching cesium in a solution, comprising the following steps:

[0034] Prussian blue analogue was synthesized by using 0.01 mol / L NiSO4 and 0.01 mol / L K4[Fe(CN)6] in a solution volume of 3:1. The obtained Prussian blue analogue and polystyrene were hydrothermally synthesized at a mass ratio of 1:1 at a temperature of 40°C and a rotation speed of 100 r / min to obtain 12 g of Prussian blue analogue film. The surface area of ​​the Prussian blue analogue film was 50 cm 2 The anode is a platinum electrode, the cathode is a copper electrode, and the surface area of ​​the electrode sheet is 40cm 2 , the current density is 0.6A / m 2 , the electrolysis voltage is controlled to be 0.5V, the liquid volume of the anode chamber and cathode chamber is 0.5L, and the initial cation concentration of the anode chamber is as follows:

[0035]

[0036] After 3 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0037]

[0038] The separation factor f of cesium and strontium is obtained Cs / S r = 83, the separation factor f of cesium lanthanum Cs / La =167, the separation factor f of cesium zirconium Cs / Z r=500.

[0039] Example 2

[0040] A method for separating and enriching cesium in a solution, comprising the following steps:

[0041] Prussian blue analogue was synthesized by using 0.08 mol / L FeSO4 and 0.04 mol / L K3[Fe(CN)6] in a solution volume of 1:1. The obtained Prussian blue analogue and polyamide were hydrothermally synthesized at a mass ratio of 1:5 at a temperature of 50°C and a rotation speed of 200 r / min to obtain 12 g of Prussian blue analogue film. The surface area of ​​the Prussian blue analogue film was 50 cm 2 The anode is a platinum electrode, the cathode is a platinum electrode, and the surface area of ​​the electrode sheet is 40cm 2 , the current density is 1.8A / m 2 , the electrolysis voltage was controlled to be 1.5V, the liquid volume of the anode chamber and cathode chamber was 0.5L, and the initial cation concentration of the anode chamber was as follows:

[0042]

[0043] After 3 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0044]

[0045] The separation factor f of cesium and strontium is obtained Cs / Sr =15, the separation factor f of cesium lanthanum Cs / La =37.5, the separation factor f of cesium zirconium Cs / Zr =75.

[0046] Example 3

[0047] Prussian blue analogue was synthesized by using 0.1 mol / L FeCl2 and 0.1 mol / L K3[Co(CN)6] in a solution volume of 2:1. The obtained Prussian blue analogue and sulfonated polysulfone were hydrothermally synthesized at a mass ratio of 3:1 at a temperature of 60°C and a rotation speed of 300 r / min to obtain 12 g of Prussian blue analogue membrane. The surface area of ​​the Prussian blue analogue membrane was 50 cm 2 The anode is a graphite electrode, the cathode is a platinum electrode, and the surface area of ​​the electrode sheet is 40cm 2 , the current density is 3.6A / m 2, the electrolysis voltage was controlled to be 3.0V, the liquid volume of the anode chamber and cathode chamber was 0.5L, and the initial cation concentration of the anode chamber was as follows:

[0048]

[0049] After 6 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0050]

[0051] The separation factor f of cesium and strontium is obtained Cs / Sr =113, the separation factor f of cesium lanthanum Cs / La =225, the separation factor f of cesium zirconium Cs / Zr =450.

[0052] Example 4

[0053] Prussian blue analogue was synthesized by using 0.3 mol / L Zn(NO3)2 and 0.1 mol / L Na3[Co(CN)6] in a solution volume of 1:1. The obtained Prussian blue analogue and polyvinylidene fluoride were hydrothermally synthesized at a mass ratio of 5:1 at 70°C and a rotation speed of 400 r / min to obtain 12 g of Prussian blue analogue film. The surface area of ​​the Prussian blue analogue film was 50 cm 2 The anode uses a graphite electrode, the cathode is a copper electrode, and the surface area of ​​the electrode sheet is 40cm 2 , current density is 6A / m 2 , the electrolysis voltage was controlled to be 5.0V, the liquid volume of the anode chamber and cathode chamber was 0.5L, and the initial cation concentration of the anode chamber was as follows:

[0054]

[0055]

[0056] After 6 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0057]

[0058] The separation factor f of cesium and strontium is obtained Cs / Sr =98, the separation factor f of cesium lanthanum Cs / La =163, the separation factor f of cesium zirconium Cs / Zr =490.

[0059] Example 5

[0060] Prussian blue analogue was synthesized by using 0.5 mol / L CoCl2 and 1 mol / L K3[Ni(CN)6] with a solution volume of 4:1. The obtained Prussian blue analogue and polyvinyl chloride were hydrothermally synthesized at a mass ratio of 10:1 at a temperature of 80°C and a rotation speed of 500 r / min to obtain 12 g of Prussian blue analogue film. The surface area of ​​the Prussian blue analogue film was 50 cm 2 The anode uses a graphite electrode, the cathode is a copper electrode, and the surface area of ​​the electrode sheet is 40cm 2 , current density is 6A / m 2 , the electrolysis voltage was controlled to be 5.0V, the liquid volume of the anode chamber and cathode chamber was 0.5L, and the initial cation concentration of the anode chamber was as follows:

[0061]

[0062] After 6 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0063]

[0064]

[0065] The separation factor f of cesium and strontium is obtained Cs / Sr =163, the separation factor f of cesium lanthanum Cs / La =245, the separation factor f of cesium zirconium Cs / Zr =490.

[0066] Example 6

[0067] Prussian blue analogue was synthesized by using 0.4 mol / L MnCl2 and 0.2 mol / L Na3[Fe(CN)6] in a solution volume of 1:1. The obtained Prussian blue analogue and polyvinylidene fluoride were hydrothermally synthesized at a temperature of 90°C and a rotation speed of 600 r / min in a mass ratio of 1:1 to obtain 12 g of Prussian blue analogue film. The surface area of ​​the Prussian blue analogue film was 50 cm 2 The anode is a platinum electrode, the cathode is a copper electrode, and the surface area of ​​the electrode sheet is 40cm 2 , current density is 12A / m 2 , the electrolysis voltage was controlled to be 10V, the liquid volume of the anode chamber and cathode chamber was 0.5L, and the initial cation concentration of the anode chamber was as follows:

[0068]

[0069] After 3 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0070]

[0071] The separation factor f of cesium and strontium is obtainedCs / Sr =49.5, the separation factor f of cesium lanthanum Cs / La =198, the separation factor f of cesium zirconium Cs / Zr =330.

[0072] Example 7

[0073] Prussian blue analogue was synthesized by using 0.2 mol / L CuSO4 and 0.4 mol / L Na3[Co(CN)6] with a solution volume of 3:1. The obtained Prussian blue analogue and polytetrafluoroethylene were hydrothermally synthesized at a mass ratio of 1:1 to obtain 12 g of Prussian blue analogue film. The surface area of ​​the Prussian blue analogue film was 50 cm 2 The anode is a platinum electrode, the cathode is a copper electrode, and the surface area of ​​the electrode sheet is 5cm 2 , current density is 96A / m 2 , the electrolysis voltage was controlled to be 10V, the liquid volume of the anode chamber and cathode chamber was 0.5L, and the initial cation concentration of the anode chamber was as follows:

[0074]

[0075] After 3 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0076]

[0077] The separation factor f of cesium and strontium is obtained Cs / Sr =12, the separation factor f of cesium lanthanum Cs / La =49, the separation factor f of cesium zirconium Cs / Zr =75.

[0078] Comparative Example 1

[0079] Using only polyvinylidene fluoride as raw material, 12g of film was hydrothermally synthesized with a surface area of ​​50cm 2 At a temperature of 60°C and a rotation speed of 500 r / min, the anode is a graphite electrode, the cathode is a copper electrode, and the surface area of ​​the electrode sheet is 40 cm 2 , current density is 12A / m 2 , the electrolysis voltage was controlled to be 10.0V, the liquid volume of the anode chamber and cathode chamber was 0.5L, and the initial cation concentration of the anode chamber was as follows:

[0080]

[0081]

[0082] After 6 hours of electrolysis, the cation concentration in the anode chamber is as follows:

[0083]

[0084] The separation factor f of cesium and strontium is obtained Cs / Sr =1.14, the separation factor f of cesium lanthanum Cs / La =0.95, the separation factor f of cesium zirconium Cs / Zr =1.05.

[0085] Comparative Example 2

[0086] Prussian blue was synthesized by using 0.05 mol / L FeCl2 and 0.1 mol / L Na3[Fe(CN)6] in a solution volume of 3:1. The obtained Prussian blue and polysulfone were hydrothermally synthesized at a mass ratio of 1:5 at a temperature of 80°C and a rotation speed of 400 r / min to obtain 12 g of Prussian blue analog film. The surface area of ​​the Prussian blue analog film was 50 cm 2 The anode is a platinum electrode, the cathode is a platinum electrode, and the surface area of ​​the electrode sheet is 40cm 2 Without using an external electric field and relying on concentration difference as the driving force, the liquid volume of the anode chamber and cathode chamber is 0.5L, and the initial cation concentration of the anode chamber is as follows:

[0087]

[0088] After the solution was left to stand for 6 hours, the cation concentration in the anode chamber was as follows:

[0089]

[0090] The ion concentration in the solution barely changes after the applied electric field is removed.

[0091] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for separating and enriching cesium in a solution, characterized in that: Under the action of electric field, cesium ions are enriched through the selective Prussian blue analog membrane; It includes the following steps: S1. Synthesis of Prussian blue analog film: The synthetic chemical formula is A x M Ay [M B (CN)6] Z -nH2O Prussian blue analogue, reacting with an organic binder through hydrothermal reaction to form a film casting solution, and the film casting solution is made into a Prussian blue analogue film; Where 0≤x≤2, 1≤y≤4, 1≤z≤3, A represents an alkali metal, M A and M B Any one of Fe, Cr, Ti, Ni, Co, Mn, Cu and Zn; S2. Construction of separation system: A Prussian blue analog membrane is used as a 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; S3. Separation of cesium ions in solution: The electric field of the solution is controlled by the working electrode, so that cesium ions are enriched in the cathode chamber through the Prussian blue analog membrane from the anode chamber.

2. The separation and enrichment method according to claim 1, characterized in that: The raw material for synthesizing Prussian blue is M Am Y n and A x [M B (CN)6]; where 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.

3. The separation and enrichment method according to claim 2, characterized in that: M Am Y n With A x [M B The molar ratio of (CN)6] is 1 to 3:1, and the solution concentration is 0.01 mol / L to 1 mol / L.

4. The separation and enrichment method according to claim 1, characterized in that: The organic binder includes any one or more of polystyrene, polyamide, sulfonated polysulfone, polyvinylidene fluoride, polyvinyl chloride, polypropylene, polysulfone and polytetrafluoroethylene.

5. The separation and enrichment method according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 40-90° C., and the rotation speed is 100-600 r / min.

6. The separation and enrichment method according to claim 1, characterized in that: The casting solution is used to prepare a Prussian blue analog film through a spin coating method, a dip coating method, a phase conversion method or a hot pressing molding method.

7. The separation and enrichment method according to claim 1, characterized in that: In the working electrode, the anode can be an inert electrode or a soluble electrode, and the cathode can be a graphite electrode, a copper electrode, a platinum electrode, etc.

8. The separation and enrichment method according to claim 1, characterized in that: The pH of the solution to be treated and the blank solution is -0.5 to 7; the electrolysis voltage is 0.5 to 10 V, and the current density is 0.1 to 100 A / m 2 .

9. The separation and enrichment method according to claim 1, characterized in that: The thickness of the Prussian blue analog film is 50-1000 μm.

Images