Application of perovskite-based titanate adsorbent to enrichment of strontium by using ion exchange method and electrochemical switch ion exchange method

Abstract

The invention discloses application of a perovskite-based titanate adsorbent to enrichment of strontium by using an ion exchange method and an electrochemical switch ion exchange method, and belongs to the technical field of strontium-containing wastewater treatment. The strontium ion adsorbent is titanate of a Ruddlesden-Popper type perovskite structure, contains rare earth metal Ln and variable valence metal Ti, has a [Ln2Ti3O10] n2n-layered framework, and alkali metal ions are arranged between layers, and the strontium ion adsorbent can deeply remove < 90 > Sr in actual acid waste liquid generated in the industrial production process. After the strontium ion adsorbent is prepared into a working electrode, strontium ions in a water body can be enriched through an electrochemical switch ion exchange method, the strontium ion adsorbent has high adsorption capacity and good selectivity in neutral and acid solutions, and regeneration and recycling of the working electrode can be achieved through change of applied potential.

Description

Technical Field

[0001] The present application relates to the application of a perovskite-based titanate adsorbent for enriching strontium using an ion exchange method and an electrochemical switch ion exchange method, and belongs to the field of strontium-containing wastewater treatment technology. Background Art

[0002] With the rapid development of nuclear energy, the public is paying more and more attention to nuclear safety issues. 90 Sr(t 1 / 2 ~28 years) as 235 U fission products are one of the main sources of beta radioactivity in spent fuel. Due to their strong radioactivity, high solubility and easy migration, they will cause serious harm to the ecosystem once released into the environment. 90 Sr 2+ Ions are an urgent need for the sustainable development of nuclear energy and spent fuel reprocessing. However, the complex environment has a great impact on the radioactive waste liquid. 90 Sr 2+ The selective separation of

[0003] Ion exchange method for the removal of Sr 2+ However, traditional ion exchange materials have good application prospects in Sr 2+ The adsorption capacity is low and the selectivity is poor. The electrochemically switched ion exchange (ESIX) method combines electrochemical adsorption and ion exchange and is a promising method for removing radionuclides. Compared with the traditional ion exchange method, ESIX can significantly enhance the adsorption capacity by adjusting the voltage and minimize the formation of secondary pollutants in a more sustainable and environmentally friendly way. However, ESIX has not yet been used to treat Sr 2+ , which may be due to Sr 2+ The large hydration radius and high valence of Sr lead to difficulties in ion migration and reversible insertion. 2+ The key to this is developing electrode materials with excellent structural stability, enabling dynamic response to electric fields while also exhibiting ion exchange properties. Perovskite oxides, as a versatile class of materials, possess excellent water stability, tunable structures, and abundant active sites, making them well-suited for radionuclide adsorption. However, their application in radioactive strontium capture remains exploratory. Summary of the Invention

[0004] In order to solve the problems of low adsorption capacity and poor selectivity of traditional ion exchange materials in the existing technology for treating strontium-containing wastewater, and the difficulty of strontium ion migration and reversible insertion in the electrochemical switch ion exchange method, this application proposes a technical solution for electrochemical switch ion exchange using electroactive layered titanate-based perovskite as a strontium ion adsorbent for enriching and recovering strontium in water. The Ruddlesden-Popper type titanate such as Na2La2Ti3O 10 The working electrode is used to enrich and recover strontium in water. It has a high adsorption capacity and good selectivity in neutral and acidic solutions for the extraction of strontium ions from water. The adsorbed strontium ions can be quickly released into the solution by changing the applied potential, achieving regeneration and recycling of the electrode.

[0005] This application adopts the following technical solutions:

[0006] According to a first aspect of the present application, there is provided an application of a perovskite-based titanate adsorbent for enriching strontium using an ion exchange method, the ion exchange method comprising contacting the strontium ion adsorbent with water containing strontium ions;

[0007] The strontium ion adsorbent is a titanate with a Ruddlesden-Popper perovskite structure;

[0008] The strontium ion adsorbent has [Ln2Ti3O 10 ] n 2n- Layered skeleton, the [Ln2Ti3O 10 ] n 2n- The interlayers of the layered skeleton are alkali metal ions, where n is a way of expressing the anion layer and does not involve a specific range of values.

[0009] Optionally, Ln is selected from at least one rare earth element.

[0010] Optionally, Ln is selected from at least one of Nd, Sm, Eu, Gd, Dy, and La.

[0011] The strontium ion adsorbent is an electroactive layered titanate-based perovskite, in which [Ln2Ti3O 10 ] n 2n- The layered skeleton contains rare earth metal Ln and variable valence metal Ti, and the interlayers are alkali metal ions, which have certain adsorption properties for strontium ions.

[0012] Optionally, the [Ln2Ti3O 10 ] n 2n- The initial valence of Ti in the layered framework is independently +4;

[0013] Optionally, the [Ln2Ti3O 10 ] n 2n- Ln in the layered skeleton is La.

[0014] Optionally, the [Ln2Ti3O 10 ] n 2n- The interlayer of the layered skeleton is Na + ion.

[0015] Optionally, the chemical formula of the strontium ion adsorbent is Na2La2Ti3O 10 .

[0016] Optionally, the preparation method of the strontium ion adsorbent comprises the following steps:

[0017] The mixture containing alkali metal carbonate, TiO2 and La2O3 is ground uniformly, then calcined, slowly cooled to room temperature, washed, filtered and separated, and dried to obtain the strontium ion adsorbent.

[0018] Optionally, alkali metal carbonate, TiO2, and La2O3 are mixed in a stoichiometric ratio of the strontium ion adsorbent.

[0019] Optionally, the calcination conditions include: maintaining the calcination temperature at 800-1000° C. for 24-36 hours.

[0020] Optionally, the slow cooling condition includes: cooling from the calcination temperature to room temperature for 24 to 48 hours.

[0021] Optionally, the water containing strontium ions is 90 Sr waste liquid.

[0022] Optionally, the pH value of the water containing strontium ions is 3.75.

[0023] Optionally, the mixing ratio of the strontium ion adsorbent and the water containing strontium ions is 5-40 mg:5 mL.

[0024] According to a second aspect of the present application, there is provided an application of a perovskite-based titanate adsorbent for enriching strontium using an electrochemical switch ion exchange method, wherein the electrochemical switch ion exchange method is performed in a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode;

[0025] The steps of the electrochemical switch ion exchange method include:

[0026] Adsorption process: under the condition of applying a negative external voltage to the working electrode, the working electrode is contacted with the water containing strontium ions until the strontium ion adsorbent and the water containing strontium ions reach adsorption equilibrium, thereby completing strontium ion enrichment;

[0027] Desorption process: Under the condition of applying a positive external voltage to the working electrode, the working electrode after adsorption equilibrium is placed in water to desorb the adsorbed strontium ions to complete the strontium ion recovery.

[0028] The working electrode includes a conductive substrate and a coating containing a strontium ion adsorbent disposed on the surface of the conductive substrate;

[0029] The strontium ion adsorbent is a titanate with a Ruddlesden-Popper perovskite structure;

[0030] The strontium ion adsorbent has [Ln2Ti3O 10 ] n 2n- Layered skeleton, the [Ln2Ti3O 10 ] n 2n- The interlayers of the layered skeleton are alkali metal ions.

[0031] Optionally, Ln is selected from at least one rare earth element.

[0032] Optionally, Ln is selected from at least one of Nd, Sm, Eu, Gd, Dy, and La.

[0033] The strontium ion adsorbent is an electroactive layered titanate-based perovskite, in which [Ln2Ti3O 10 ] n 2n- The layered skeleton contains rare earth metal Ln and variable valence metal Ti, and the interlayers are alkali metal ions, which have certain adsorption properties for strontium ions.

[0034] Optionally, the [Ln2Ti3O 10 ] n 2n- The initial valence of Ti in the layered framework is independently +4;

[0035] Optionally, the [Ln2Ti3O 10 ] n 2n- Ln in the layered skeleton is La.

[0036] Optionally, the [Ln2Ti3O 10 ] n 2n- The interlayer of the layered skeleton is Na + ion.

[0037] Optionally, the chemical formula of the strontium ion adsorbent is Na2La2Ti3O 10 .

[0038] Optionally, the counter electrode is carbon cloth, and the reference electrode is a saturated calomel electrode (Hg / Hg2Cl2 / KCl saturated solution).

[0039] Optionally, the preparation method of the strontium ion adsorbent comprises the following steps:

[0040] The mixture containing alkali metal carbonate, TiO2 and La2O3 is ground uniformly, then calcined, slowly cooled to room temperature, washed, filtered and separated, and dried to obtain the strontium ion adsorbent.

[0041] Optionally, the preparation step of the working electrode includes: coating a slurry containing the strontium ion adsorbent, conductive carbon black, polymer, and organic solvent on the surface of a conductive substrate and then curing the slurry.

[0042] Optionally, the concentration of strontium ions in the water body is 10 to 70 mg / L.

[0043] Optionally, the content of the strontium ion adsorbent in the working electrode is 70-110 mg / cm 2 .

[0044] Optionally, the pH value of the water containing strontium ions is 1-11.

[0045] Optionally, the pH value of the water containing strontium ions is independently selected from any value among 1, 3, 5, 7, 9, 11 or any range between two values.

[0046] Optionally, the pH value of the water containing strontium ions is 7.

[0047] Optionally, during the adsorption process, the applied voltage of the working electrode is 0 to -4V.

[0048] Optionally, during the adsorption process, the applied voltage of the working electrode is preferably -4V.

[0049] Optionally, during the desorption process, the applied voltage of the working electrode is 4V.

[0050] Optionally, the temperature condition of the adsorption process and the desorption process is room temperature.

[0051] Optionally, during the adsorption process, the applied voltage of the working electrode is selected from any value of 0, -1V, -2V, -3V, -4V, or a range of values ​​therebetween.

[0052] Optionally, the water body containing strontium ions is strontium-containing radioactive wastewater and / or a strontium-contaminated water source.

[0053] Optionally, the water containing strontium ions is neutral waste liquid or acidic waste liquid.

[0054] Optionally, the water containing strontium ions contains alkali metal ions and alkaline earth metal ions.

[0055] Optionally, the alkali metal ion is selected from at least one of sodium ion, potassium ion and cesium ion.

[0056] Optionally, the alkaline earth metal ions are selected from at least one of calcium ions and magnesium ions.

[0057] Optionally, the concentration ratio of alkali metal ions and / or alkaline earth metal ions to strontium ions in the water containing strontium ions is 0.5-2.

[0058] Optionally, the molar ratio of alkali metal ions and / or alkaline earth metal ions to strontium ions in the water containing strontium ions is 0.61 to 1.16.

[0059] Optionally, the temperature of the water containing strontium ions is 25°C.

[0060] Optionally, after adsorption equilibrium is reached, the contact is stopped.

[0061] Room temperature in this application refers to 20-35°C.

[0062] The beneficial effects of this application include:

[0063] (1) The strontium ion adsorbent provided by the present application has a certain adsorption performance for strontium ions. The adsorbent has good irradiation stability. After 100kGy and 200kGy of γ irradiation, the framework remains stable, the removal rate of strontium ions remains almost unchanged, and the removal rate of strontium ions is greater than 95%. The adsorbent has good thermal stability. It loses less than 5% of its mass in the range of room temperature to 1200°C. After thermogravimetric testing at 1200°C, the layered structure remains stable and the adsorbent can still maintain its framework structure. The adsorbent is stable at 10 -7 The framework is kept stable in nitric acid solution of 2 mol / L, and the metal overflow rate is less than 7%. The adsorbent can be used for the actual acidic waste liquid (pH=3.75) generated in the industrial production process. 90 Sr was deeply removed, and the removal rate was as high as over 99% when the solid-liquid ratio was 8 mg / mL.

[0064] (2) The strontium ion adsorbent provided by the present application is prepared into a working electrode, and the electrochemical switch ion exchange method is used to enrich and recover strontium in the water body. The adsorption capacity of strontium ions in the water body is high and the selectivity is good in neutral and acidic solutions. The adsorbed strontium ions can be quickly released by changing the applied potential, thereby realizing the regeneration and recycling of the electrode. Specifically, at a voltage of -4V and neutral conditions, the adsorption capacity of the adsorbent for 50mL volume 50mg / L strontium is as high as 175.42mg / g. Under acidic conditions (pH=1), the distribution coefficient of the adsorbent for strontium ions in strontium ion solution is greater than 10 3 mL / g. When strontium ions coexist with various ions, such as alkali metal ions and alkaline earth metal ions, it exhibits high selectivity for strontium ions, while most competing ions remain in the solution after adsorption. The adsorbed strontium ions can be rapidly released into the solution by changing the applied potential, enabling regeneration and recycling of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The Na2La2Ti3O in the embodiment of this application 10 Powder diffraction patterns after treatment with nitric acid solutions of different concentrations;

[0066] Figure 2 The Na2La2Ti3O in the embodiment of this application 10 Powder diffraction pattern after irradiation and removal rate diagram of strontium ions before and after irradiation (Note: a is the powder diffraction pattern, b is the removal rate diagram);

[0067] Figure 3 The Na2La2Ti3O in the embodiment of this application 10 Thermogravimetric curves and powder diffraction patterns before and after adsorption of strontium ions (Note: a is the thermogravimetric curve, b is the powder diffraction pattern);

[0068] Figure 4 Schematic diagram of the three-electrode system and adsorption and desorption processes of this application (Note: a is a schematic diagram of the three-electrode system structure; b is a schematic diagram of ion movement during adsorption; c is a schematic diagram of ion movement during desorption);

[0069] Figure 5 The Na2La2Ti3O in the embodiment of this application 10 The adsorption results of strontium ions under different applied voltages;

[0070] Figure 6 The Na2La2Ti3O in the embodiment of this application 10 Adsorption kinetics of strontium ions (Note: applied voltage is -4V, neutral conditions);

[0071] Figure 7The Na2La2Ti3O in the embodiment of this application 10 The distribution coefficient of strontium ions in the pH range of 1 to 11 (Note: the applied voltage is -4V);

[0072] Figure 8 The Na2La2Ti3O in the embodiment of this application 10 In Na + , K + 、Cs + , Ca 2+ Mg 2+ The distribution coefficient results of strontium ions under coexistence (Note: the applied voltage is -4V; a is neutral conditions; b is pH = 3; c is pH = 1);

[0073] Figure 9 The Na2La2Ti3O in the embodiment of this application 10 Cyclic stability results (Note: a is Na2La2Ti3O 10 CV curves at different scan rates in 50 mg / L SrCl2·6H2O solution; b is Na2La2Ti3O 10 CV curves of the 1st to 100th cycles at 0.08 V / s; c is the four adsorption and desorption cycles of strontium ions). DETAILED DESCRIPTION

[0074] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0075] Unless otherwise specified, the raw materials in the examples of this application were purchased from commercial channels and used directly without any special treatment.

[0076] Unless otherwise specified, the analytical methods in the examples all adopt conventional settings and conventional analytical methods of instruments or equipment.

[0077] The analysis methods in the following examples are as follows:

[0078] Electrochemical tests were performed in an electrochemical workstation (CHI660E, CH Instruments, China).

[0079] Inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES) were performed on an XSerise II and a Thermo 7400 instrument, respectively.

[0080] X-ray powder diffraction (PXRD) analysis was performed on a Rigaku MiniFlex II diffractometer at 30 kV and 15 mA, using a Cu target and a Kα radiation source.

[0081] Use the test center of Suzhou China Nuclear Huadong Irradiation Co., Ltd. 60 The samples were irradiated with gamma rays using a Co irradiation source (2 million Curies) with total doses of 100 kGy (1.2 kGy / h, 89 hours) and 200 kGy (1.2 kGy / h, 175 hours), respectively.

[0082] Thermogravimetric analysis (TGA) was performed on a NETZSCH STA449F3 DTA-TG analyzer from room temperature to 1200 °C at a heating rate of 10 °C / min under nitrogen atmosphere.

[0083] The adsorption capacity in the examples of this application is calculated by the following method:

[0084]

[0085] The distribution coefficient in the examples of this application is calculated by the following method:

[0086]

[0087] The removal rate in the examples of this application is calculated by the following method:

[0088]

[0089] The leaching rate in the examples of this application is calculated by the following method:

[0090]

[0091] In the above formula, C0 and C e (mg / L) represent the initial concentration and equilibrium concentration of strontium solution, K d (mL / g) represents the distribution coefficient of various ions, C A and C T (mg / L) represents the concentration of ions overflowing from the material when it is immersed in the solution for a period of time and the theoretical concentration of ions completely dissolved in the solution.

[0092] Example 1

[0093] Na2La2Ti3O 10 Preparation:

[0094] Na2CO3 (2.8 mmol, 0.2968 g), TiO2 (6 mmol, 0.4792 g), and La2O3 (2 mmol, 0.6516 g) were mixed in a stoichiometric ratio and ground uniformly. The mixture was placed in a 20 mL round-bottomed alumina crucible and maintained at 900°C for 24 hours, followed by slow cooling to room temperature over 48 hours. The product was rinsed with deionized water and ethanol multiple times, separated by filtration, and finally dried in an 80°C oven overnight to obtain a pure off-white powder, Na2La2Ti3O 10 .

[0095] Test Example 1

[0096] Na2La2Ti3O 10 Acid stability test:

[0097] The Na2La2Ti3O prepared in Example 1 10 At different concentrations (such as Figure 1 The sample was stirred at 600 rpm for 12 hours in an HNO3 solution (concentration indicated in the figure). After solid-liquid separation, the leaching concentrations of Ti and La in the solution were determined by ICP-OES or ICP-MS, and the leaching rates of Ti and La in the sample were calculated. After treatment with nitric acid of different molar concentrations, the metal overflow rate in the solution was less than 7%. The solid material was subjected to powder diffraction analysis to determine whether the material skeleton was stable. The test results are shown in Figure 2. Figure 1 As shown. Figure 1 It can be seen that after being treated with nitric acid of different molar concentrations, the material of the present application can still maintain a stable skeleton.

[0098] Test Example 2

[0099] Na2La2Ti3O 10 Radiation stability test:

[0100] Na2La2Ti3O 10 Place 60 The samples were irradiated with a total dose of 100 kGy (1.2 kGy / h, for 89 h) and 200 kGy (1.2 kGy / h, for 175 h) of gamma rays in a Co irradiation source. Figure 2 As shown. Figure 2 It can be seen from a that after irradiation, the frame structure of the sample remains stable. Figure 2 b It can be seen that the adsorption performance of strontium ions remains basically unchanged, proving that the material of the present application has good radiation resistance.

[0101] Test Example 3

[0102] Na2La2Ti3O 10 Thermal stability test before and after strontium adsorption:

[0103] Na2La2Ti3O 10 The samples before and after strontium adsorption were placed on a DTA-TG analyzer, and the temperature was raised from room temperature to 1200°C at a rate of 10°C / min using a nitrogen atmosphere. Figure 3 As shown. Figure 3 b shows that the frame structure of the sample remains stable after heating. Figure 3 As shown in a, the weight loss of the sample from 20°C to 1200°C is less than 5%. The test results show that the material of the application has good thermal stability.

[0104] Test Example 4

[0105] Na2La2Ti3O 10 Removal in actual wastewater 90 Sr's ability test:

[0106] 40 mg of Na2La2Ti3O 10 With 90 The mixture was mixed with 5 mL of actual waste liquid of Sr, stirred at 200 r / min for 4 h at 25 °C, and the supernatant was filtered through a 0.1 μm microporous filter membrane. 1 mL of the solution was sampled and measured. 90 The activity of Sr changes. The results show that Na2La2Ti3O 10 The actual content of 90 Strontium can be efficiently removed from Sr waste liquid. The initial activity of the waste liquid is 3042Bq / mL, and the activity after treatment is 25Bq / mL. The deactivation rate of strontium is as high as 99.18%.

[0107] Example 2

[0108] Na2La2Ti3O 10 The electrodes are prepared and form a three-electrode system:

[0109] The Na2La2Ti3O prepared in Example 1 10 , conductive carbon black and polyvinylidene fluoride (PVDF) were dispersed in N-methylpyrrolidone (NMP) at a mass ratio of 8:1:1 at room temperature. The prepared slurry was coated on a carbon cloth (1.0×1.0 cm 2 ) as the working electrode, and prepare a carbon cloth (1.0×1.0cm 2 ) is the auxiliary electrode, and the saturated calomel electrode (Hg / Hg2Cl2 / KCl saturated solution) is the reference electrode. The schematic diagram of the three-electrode system and the adsorption and desorption process is shown in Figure 4 shown.

[0110] Test Example 5

[0111] In the three-electrode system of Example 2, the adsorption capacity of strontium by the working electrode was tested at different applied voltages:

[0112] The working electrode was exposed to a neutral aqueous solution with an initial strontium concentration of 57.88 mg / L at different applied voltages. The solution volume was 50 mL and the current was applied at 25°C for 4 hours. After adsorption was complete, the supernatant and the initial solution were taken and the strontium concentration was determined by inductively coupled plasma emission spectroscopy. The experimental results are shown in Figure 2. Figure 5 As shown. Figure 5 It can be seen that in the voltage range of 0 to -1 V, the adsorption capacity remains almost stable. When the potential increases to above -2 V, the adsorption capacity begins to increase significantly, and finally reaches 175.43 mg / g at -4 V.

[0113] Test Example 6

[0114] Adsorption kinetics test of the working electrode for the electrochemical switching ion exchange method under the three-electrode system of Example 2:

[0115] The working electrode was placed in contact with a neutral solution with an initial strontium concentration of 58.25 mg / L, and the applied voltage was -4 V. The solution volume was 50 mL, and the current was applied at 25°C for 4 hours. A small amount of the supernatant was taken at regular intervals and the ion concentration was measured using inductively coupled plasma emission spectrometry. The test results are as follows: Figure 6 As shown. Figure 6 It can be seen that the adsorption of strontium reaches equilibrium after 4 hours.

[0116] Test Example 7

[0117] In the three-electrode system of Example 2, the ability of the working electrode used in the electrochemical switch ion exchange method to adsorb strontium at different pH values ​​was tested:

[0118] The working electrode was placed in contact with strontium solutions of varying pH values, with an applied voltage of -4 V. The solution volume was 50 mL, and the initial concentration was 9.96 to 11.88 mg / L. The current was applied at 25°C for 4 hours. After adsorption was complete, the supernatant and initial solution were taken and the ion concentrations were determined using inductively coupled plasma emission spectroscopy. The results are shown in Figure 2. Figure 7 As shown. Figure 7 It can be seen that the sample can maintain its strontium removal activity within the pH range of 1 to 11.

[0119] Test Example 8

[0120] In the three-electrode system of Example 2, the ability of the working electrode used in the electrochemical switch ion exchange method to selectively adsorb strontium at different pH values ​​was tested:

[0121] The working electrode was exposed to strontium solutions of varying pH values ​​containing various competing ions, including alkali metal and alkaline earth metal ions. A voltage of -4 V was applied, and the solution volume was 50 mL, at 25°C for 4 hours. After adsorption, the supernatant and initial solutions were collected and the concentrations of strontium and other ions were determined using inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry, respectively. Figure 8 For Na + , K + 、Cs + , Ca 2+ Mg 2+ The removal ability of samples to strontium under coexistence. Figure 8 It can be seen from a that when the mass concentration of the competing ion is almost the same as that of strontium, the distribution coefficient can reach 4.23×10 3 mL / g, indicating that the sample has a high selectivity for strontium. Figure 8 a. Figure 8 b shows that when the acidity of the solution increases to pH = 3 or even pH = 1, the distribution coefficient of the sample remains at 2.95×10 3 mL / g and 7.56×10 2 mL / g. It can be seen that the sample still has good selectivity for strontium in acidic solution and is particularly suitable for the removal of strontium in acidic radioactive wastewater (Note: The use of the reference electrode results in K + As the concentration increases, Sr 2+ and Na + The ion exchange between Na + The concentration increases, so Figure 8 Na is not shown in + and K + data).

[0122] Test Example 9

[0123] Cyclic stability test of the working electrode used in the electrochemical switching ion exchange method under the three-electrode system of Example 2:

[0124] The cyclic voltammetry curves of the working electrode at different scan rates of 0.02 to 0.1 V / s were tested. Figure 9 a It can be seen that the redox peak is very broad, indicating that Na2La2Ti3O 10 With the increase of scan rate, there is a slight peak shift, but the overall shape of the redox peak remains unchanged, which means that even at high scan rates, Na2La2Ti3O 10 The capacity is still reversible. In addition, the cycling stability of the electrode is an important indicator for evaluating whether the electrochemical switch ion exchange method can efficiently adsorb and desorb. Figure 9b It can be seen that at a scan rate of 0.08 V / s, after 100 electrochemical redox processes, the cyclic voltammetry curve did not change significantly, proving that Na2La2Ti3O 10 It has good stability in the electrochemical process. In order to further test the complete adsorption and desorption cycle of the electrochemical adsorption process, the sample was reused for 4 cycles. Figure 9 As shown in c, the adsorption process of strontium on the sample was studied in a solution containing 67.70 mg / L strontium at -4 V; the desorption process was carried out in a 0.5 mol / L NaCl solution at 4 V. The experimental results show that after 4 cycles, Na2La2Ti3O 10 The adsorption and desorption capabilities remain good, and the adsorption amount remains above 170.32 mg / g.

[0125] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An application of a perovskite-based titanate adsorbent for enriching strontium using an ion exchange method, characterized in that: The ion exchange method includes contacting a strontium ion adsorbent with water containing strontium ions; The strontium ion adsorbent is a titanate with a Ruddlesden-Popper perovskite structure; The strontium ion adsorbent has [Ln2Ti3O 10 ] n 2n- Layered skeleton, the [Ln2Ti3O 10 ] n 2n- The interlayers of the layered skeleton are alkali metal ions.

2. The use according to claim 1, characterized in that Ln is at least one selected from rare earth elements.

3. The use according to claim 1, characterized in that The chemical formula of the strontium ion adsorbent is Na2La2Ti3O 10 .

4. The use according to claim 1, characterized in that The preparation method of the strontium ion adsorbent comprises the following steps: The mixture containing alkali metal carbonate, TiO2 and La2O3 is ground uniformly, then calcined, slowly cooled to room temperature, washed, filtered and separated, and dried to obtain the strontium ion adsorbent.

5. The use according to claim 1, characterized in that The water containing strontium ions is 90 Sr waste liquid; Preferably, the pH value of the water containing strontium ions is 3.

75.

6. The use according to claim 1, characterized in that The mixing ratio of the strontium ion adsorbent and the water containing strontium ions is 5-40 mg:5 mL.

7. An application of a perovskite-based titanate adsorbent for enriching strontium using an electrochemical switch ion exchange method, characterized in that: The electrochemical switch ion exchange method is carried out in a three-electrode system consisting of a working electrode, a counter electrode and a reference electrode; The steps of the electrochemical switch ion exchange method include: Adsorption process: under the condition of applying a negative external voltage to the working electrode, the working electrode is contacted with the water containing strontium ions until the strontium ion adsorbent and the water containing strontium ions reach adsorption equilibrium, thereby completing strontium ion enrichment; Desorption process: under the condition of applying a positive external voltage to the working electrode, placing the working electrode after adsorption equilibrium in water to desorb the adsorbed strontium ions to complete strontium ion recovery; The working electrode includes a conductive substrate and a coating containing a strontium ion adsorbent disposed on the surface of the conductive substrate; The strontium ion adsorbent is a titanate with a Ruddlesden-Popper perovskite structure; The strontium ion adsorbent has [Ln2Ti3O 10 ] n 2n- Layered skeleton, the [Ln2Ti3O 10 ] n 2n- The interlayers of the layered skeleton are alkali metal ions.

8. The use according to claim 7, characterized in that The Ln is selected from at least one rare earth element; Preferably, the chemical formula of the strontium ion adsorbent is Na2La2Ti3O 10 ; Preferably, the preparation method of the strontium ion adsorbent comprises the following steps: The mixture containing alkali metal carbonate, TiO2 and La2O3 is ground uniformly, then calcined, slowly cooled to room temperature, washed, filtered and separated, and dried to obtain the strontium ion adsorbent; Preferably, the preparation step of the working electrode comprises: coating a slurry containing the strontium ion adsorbent, conductive carbon black, polymer, and organic solvent on the surface of a conductive substrate and then curing the slurry; Preferably, the concentration of strontium ions in the water is 10 to 70 mg / L; Preferably, the content of strontium ion adsorbent in the working electrode is 70-110 mg / cm 2 ; Preferably, the pH value of the water containing strontium ions is 1-11.

9. The use according to claim 7, characterized in that During the adsorption process, the applied voltage of the working electrode is 0 to -4 V; Preferably, during the desorption process, the applied voltage of the working electrode is 4V; Preferably, the temperature conditions of the adsorption process and the desorption process are room temperature.

10. The use according to claim 7, characterized in that The water containing strontium ions is neutral waste liquid or acidic waste liquid; Preferably, the water containing strontium ions contains alkali metal ions and alkaline earth metal ions; Preferably, the alkali metal ion is selected from at least one of sodium ion, potassium ion and cesium ion; Preferably, the alkaline earth metal ion is selected from at least one of calcium ion and magnesium ion.

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