Method for separating and enriching cesium in solution

Abstract

The application 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 by a selective Prussian blue diaphragm. The application draws lessons from the method of diaphragm electrolysis, combines the advantages of high selectivity of membrane separation and continuity of operation, and develops a method for continuously separating and enriching cesium from a water body under the electric driving. While realizing the industrial continuity operation, the efficient selective separation of cesium ions in the water body is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgy, and more particularly to a method for separating and enriching cesium in a solution. BACKGROUND

[0002] Cesium is an important key metal, and its application fields mainly include electronic industry, energy field, petroleum industry, medical treatment, etc. Whether extracted from ores, salt lakes or seawater, cesium needs to be separated from the solution. And the electronic and chemical enterprises related to cesium may discharge a large amount of cesium-containing wastewater in the production process, and the cesium in the wastewater also needs to be separated and enriched. The cesium-containing wastewater generated in the treatment process of the cesium-polluted area also needs to be separated. Therefore, it is urgent to develop a method for separating cesium in a solution system.

[0003] At present, the methods for treating cesium in wastewater can be summarized as follows: chemical precipitation, solvent extraction, membrane separation, adsorption, etc. Membrane separation technology is a method for selectively separating different particle sizes under the action of various driving forces, and is called membrane filtration (MF) and membrane distillation (MD) according to pressure gradient and temperature gradient. The application of membrane separation technology in cesium separation has the advantages of large decontamination factor, but the selectivity of the membrane separation for cesium is not enough at present. The present application develops a cesium separation membrane with high selectivity by means of the special selectivity of specific Prussian blue to cesium ions.

[0004] Due to the low electronegativity and large ionic radius of cesium ions, they are easy to migrate, and similar to Na and K ions, it is difficult to selectively separate them. In order to achieve high separation coefficient and purification depth, a high-efficiency separation membrane needs to be specially designed and operated. And there are a large number of ion interferences in the solution to be treated, which reduces the selectivity of cesium. Therefore, it is still an urgent task to efficiently separate cesium ions from contaminated water bodies. SUMMARY

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

[0006] In order to achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A method for efficiently separating and enriching cesium in a solution, under the action of an electric field, cesium ions are enriched by a selective Prussian blue analogue membrane.

[0008] Further, the method comprises the following steps:

[0009] S1, synthesis of a Prussian blue analogue membrane:

[0010] A Prussian blue analogue with a chemical formula of A x M Ay [M B (CN)6] Z -nH2O is hydrothermally reacted with an organic adhesive to form a casting solution, and the casting solution is made into a Prussian blue analogue membrane;

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

[0012] S2, construction of a separation system:

[0013] The Prussian blue analogue membrane is used as a diaphragm, a solution to be treated is placed in an anode chamber, and a blank solution to be enriched is placed in a cathode chamber;

[0014] S3, separation of cesium ions in a solution:

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

[0016] The Prussian blue analogue with exclusive selectivity for cesium ions is synthesized first, and then a composite membrane containing a large number of cesium ion channels is synthesized using the Prussian blue as a precursor. The size and direction of the electric field of the solution are controlled by electrodes, so that the ions in the solution move directionally. When the cations move towards the specific Prussian blue analogue membrane, the cesium ions can pass through the membrane surface due to the special structure of the membrane, while other cations in the solution are intercepted, thereby realizing efficient separation and enrichment of cesium.

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

[0018] Further, the raw material for synthesizing the Prussian blue is M Am Y n and A x [M B (CN)6]; wherein, 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] Further, the molar ratio of M Am Y n : A x [M B (CN)6] is 1-3:1, and the solution concentration is 0.01-1 mol / L.

[0020] Further, the organic binder comprises any one or several of polystyrene, polyamide, sulfonated polysulfone, polyvinylidene fluoride, polyvinyl chloride, polypropylene, polysulfone, polytetrafluoroethylene.

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

[0022] Further, the casting solution is used to prepare the Prussian blue analogue membrane by spin coating, dip coating, phase inversion or hot-pressing method.

[0023] Further, 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] Further, the solution in the cathode chamber is an acidic or neutral solution (pH = -0.5-7), the solution in the anode chamber is acidic or neutral (pH = -0.5-7), the electrolysis voltage is 0.5-10 V, and the current density is 0.1-100 A / m 2 .

[0025] Further, the thickness of the specific Prussian blue analogue membrane is 50-1000 μm.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] The application utilizes the selectivity of the Prussian blue analog film to 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 film to be enriched, so that the cesium ions in the water body are efficiently enriched. The application draws lessons from the method of diaphragm electrolysis, combines the advantages of high selectivity of membrane separation and continuous operation, and develops a method for continuously separating and enriching cesium from the water body under the electric driving. While realizing the industrial continuous operation, the efficient selective separation of the cesium ions in the water body is ensured, and a new route is provided for the treatment of cesium pollution in the water body and the hydrometallurgical process. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

[0032] Example 1

[0033] A method for separating and enriching cesium in a solution, the steps of which are as follows:

[0034] 0.01 mol / L of NiSO4 and 0.01 mol / L of K4[Fe(CN)6] are used, the solution volume is 3:1, the Prussian blue analog is synthesized, the obtained Prussian blue analog is hydrothermally synthesized with polystyrene according to a mass ratio of 1:1 at a temperature of 40℃ and a rotation speed of 100r / min to obtain a Prussian blue analog film of 12g, and the surface area of the Prussian blue analog film is 50cm 2 A platinum electrode is used for the anode, and a copper electrode is used for the cathode, the surface area of the electrode sheet is 40cm 2 , the current density is 0.6A / m 2 , the control electrolysis voltage is 0.5V, the liquid volume of the anode chamber and the cathode chamber is 0.5L, and the initial cation concentration of the anode chamber is as follows:

[0035]

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

[0037]

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

[0039] Example 2

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

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

[0042]

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

[0044]

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

[0046] Example 3

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

[0048]

[0049] The cation concentrations in the anode chamber after 6 hours of electrolysis are as follows:

[0050]

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

[0052] Example 4

[0053] Prussian blue analogues were synthesized using a 1:1 volume ratio of 0.3 mol / L Zn(NO3)2 and 0.1 mol / L Na3[Co(CN)6]. The resulting Prussian blue analogue was then hydrothermally synthesized with polyvinylidene fluoride at a 5:1 mass ratio at 70°C and 400 rpm, yielding 12 g of a Prussian blue analogue film with a surface area of ​​50 cm². 2 The anode uses a graphite electrode, and the cathode is a copper electrode; the electrode surface area is 40 cm². 2 The current density is 6A / m 2 The electrolysis voltage was controlled at 5.0V, and the liquid volume in both the anode and cathode chambers was 0.5L. The initial cation concentration in the anode chamber was as follows:

[0054]

[0055]

[0056] The cation concentrations in the anode chamber after 6 hours of electrolysis are as follows:

[0057]

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

[0059] Example 5

[0060] Prussian blue analogues were synthesized using 0.5 mol / L CoCl2 and 1 mol / L K3[Ni(CN)6] with a solution volume ratio of 4:1. The obtained Prussian blue analogues were hydrothermally synthesized into Prussian blue analogue membranes 12 g with a surface area of 50 cm2 at a temperature of 80°C and a rotation speed of 500 r / min, with polyvinyl chloride at a mass ratio of 10:1. 2 A graphite electrode was used as the anode and a copper electrode was used as the cathode, with an electrode sheet surface area of 40 cm2, a current density of 6 A / m2, and an electrolysis voltage of 5.0 V. The liquid volume in the anode chamber and the cathode chamber was 0.5 L, and the initial cation concentration in the anode chamber was as follows: 2 2

[0061]

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

[0063]

[0064]

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

[0066] Example 6

[0067] Prussian blue analogues were synthesized using 0.4 mol / L MnCl2 and 0.2 mol / L Na3[Fe(CN)6] with a solution volume ratio of 1:1. The obtained Prussian blue analogues were hydrothermally synthesized into Prussian blue analogue membranes 12 g with a surface area of 50 cm2 at a temperature of 90°C and a rotation speed of 600 r / min, with polyvinylidene fluoride at a mass ratio of 1:1. 2 A platinum electrode was used as the anode and a copper electrode was used as the cathode, with an electrode sheet surface area of 40 cm2, a current density of 12 A / m2, and an electrolysis voltage of 10 V. The liquid volume in the anode chamber and the cathode chamber was 0.5 L, and the initial cation concentration in the anode chamber was as follows: 2 2

[0068]

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

[0070]

[0071] The separation factor f of cesium and strontium was 163, the separation factor f of cesium and lanthanum was 245, and the separation factor f of cesium and zirconium was 490.​​​​​​​Cs / Sr = 49.5, separation factor f of cesium and lanthanum Cs / La = 198, separation factor f of cesium and zirconium Cs / Zr = 330.

[0072] Example 7

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

[0074]

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

[0076]

[0077] The separation factor f of cesium and strontium was obtained Cs / Sr = 49.5, separation factor f of cesium and lanthanum Cs / La = 198, separation factor f of cesium and zirconium Cs / Zr = 75.

[0078] Comparative Example 1

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

[0080]

[0081]

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

[0083]

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

[0085] Comparative Example 2

[0086] Prussian blue is synthesized using 0.05 mol / L of FeCl2 and 0.1 mol / L of Na3[Fe(CN)6] with a solution volume ratio of 3:1, and the obtained Prussian blue is hydrothermally synthesized into a Prussian blue analog film 12 g at a temperature of 80°C and a rotation speed of 400 r / min, with a mass ratio of Prussian blue to polysulfone of 1:5. The surface area of the Prussian blue analog film is 50 cm 2 A platinum electrode is used as the anode, and a platinum electrode is used as the cathode. The surface area of the electrode sheet is 40 cm 2 No external electric field is used, and the driving force relies on the concentration difference. The liquid volume of the anode chamber and the cathode chamber is both 0.5 L. The initial cation concentration in the anode chamber is as follows:

[0087]

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

[0089]

[0090] After the external electric field is removed, the ion concentration in the solution hardly changes.

[0091] The above-described examples only express several embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method for separating and enriching cesium in solution, characterized in that, Under the influence of an electric field, cesium ions are enriched through a selective Prussian blue analog membrane; It includes the following steps: Synthesis of S1, Prussian blue analogue membrane: The synthetic chemical formula is A x M Ay [M B (CN)6] Z Prussian blue analogues with -nH2O are reacted with organic binders via hydrothermal reaction to form a casting solution, which is then used to make Prussian blue analogue films. Where 0≤x≤2, 1≤y≤4, 1≤z≤3, A represents an alkali metal, and M A and M B It can be any one of Fe, Cr, Ti, Ni, Co, Mn, Cu, and Zn; S2. Construction of the separation system: Using a Prussian blue analogue membrane 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: By controlling the solution electric field through the working electrode, cesium ions are enriched in the cathode chamber from the anode chamber through a Prussian blue analog film.

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

3. The separation and enrichment method according to claim 1, characterized in that, The hydrothermal reaction temperature is 40~90℃, and the rotation speed is 100~600r / min.

4. The separation and enrichment method according to claim 1, characterized in that, The casting solution is used to prepare Prussian blue analog films by spin coating, dip coating, phase inversion or hot pressing.

5. The separation and enrichment method according to claim 1, characterized in that, In the working electrode, the anode is an inert electrode or a soluble electrode, and the cathode is any one of a graphite electrode, a copper electrode, or a platinum electrode.

6. 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 / m³. 2 .

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

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