Layered phosphate materials for radionuclide adsorption and their preparation and application

Abstract

The present invention relates to a layered phosphate material for radionuclide adsorption, as well as its preparation method and application. The method comprises the following steps: (S1) adding an alkaline hydroxide or magnesium salt, a sodium salt, and a sodium phosphate salt in a molar ratio to deionized water and stirring and mixing them uniformly; (S2) pouring the mixed solution into a high-temperature reactor for reaction to obtain a layered phosphate material. The layered phosphate material is used to adsorb radionuclide ions. Compared with existing technologies, the present invention has advantages such as high adsorption capacity, fast adsorption rate, and a wide pH range.

Description

Technical Field

[0001] The present invention belongs to the technical field of water pollution control, and in particular relates to a layered phosphate material for radionuclide adsorption, a preparation method and an application thereof. Background Art

[0002] Radioactive waste management is one of the major environmental issues facing the world today. 137 Cs, 90 Sr and 60 Co is a fission product produced by nuclear reactions with half-lives of 30.17, 28.79 and 5.27 years. Once it enters the human body, it can accumulate in the liver and kidneys. 137 The biological effects of Cs on animal organisms include acute radiation effects such as bone marrow destruction, hematopoietic dysfunction, a significant decrease in white blood cells and platelets, anemia, sepsis and hemorrhagic syndrome. 90 The chemical properties of Sr and Ca are similar. 90 After Sr enters the bone tissue, it mainly accumulates in the inorganic matter near the bone marrow cavity of the long bones, causing the bone marrow to be irradiated by β particles, which mainly causes serious damage to the bone marrow hematopoietic tissue and leads to a significant decrease in white blood cells, red blood cells and platelets. 60 Co in the human body can cause hair loss, severely damage blood cells, cause leukopenia, and lead to blood system diseases such as aplastic anemia. The complex, difficult, and expensive technology of high-level radioactive waste treatment and disposal has become a key constraint on the development of the nuclear industry.

[0003] During the research process, researchers found that ordinary phosphate materials have certain limitations in the amount of radioactive nuclides they can adsorb. Therefore, it is necessary to develop new phosphate materials to improve their adsorption capacity for radioactive nuclides. Glaserite-type layered phosphates have a variety of exchangeable ions in their structure, so they have the potential to have a large adsorption capacity for a variety of radioactive nuclides. In addition, phosphate adsorbents are used for the adsorption of heavy metal ions. For example, patent application CN 110124641A discloses a fly ash adsorption material activated by phosphoric acid, which can adsorb Sr 2+ 、Cs + and Co 2+ Produce chemical adsorption; however, the fly ash material composition is complex, the components cannot be quantified, and the adsorption capacity is low. CN 111135801A discloses a hydroxyapatite flat silk composite material with heavy metal adsorption function, but its adsorption rate is slow, and it takes more than 40 hours to achieve complete adsorption. Adsorption and removal of strontium in aqueous solution by synthetic hydroxyapatite , DOI: 10.1007 / s10967-015-4228-9 discloses hydroxyapatite for radioactive 90 Sr adsorption; Modification of hydroxyapatite for removal of cesium and strontium ions from aqueous solution , DOI: 10.1016 / j.jallcom.2017.03.156 discloses a modified hydroxyapatite, which has a great influence on the performance of Cs + and Sr 2+ The adsorption capacities of these phosphates for radionuclides are 69.49 mg / g and 13.44 mg / g, respectively. However, the adsorption capacities of these phosphates for radionuclides are low and the adsorption rates are slow.

[0004] Patent application CN201710533389.X discloses a method for preparing a magnesium phosphate nanomaterial with a mesoporous structure, which uses a water-soluble magnesium salt as a magnesium source, phosphoric acid or a water-soluble phosphate as a phosphorus source, and an aqueous solution as a solvent. The magnesium source and the phosphorus source are added to the aqueous solution at a Mg / P molar ratio of 0.5-1.5 and mixed evenly; the pH value of the solution is adjusted to 7-12, and a hydrothermal reaction is carried out at 100-200°C for 1-24 hours. The resulting precipitate is separated, washed, and dried to obtain a magnesium phosphate nanomaterial with a developed mesoporous channel structure. Although the technology mentions that the obtained mesoporous magnesium phosphate has a high specific surface area and high adsorption capacity, and has wide application value in the fields of tissue engineering, drug delivery, modern agriculture, sewage treatment, etc., it can be seen from XRD that its composition is a combination of multiple magnesium phosphate salt compounds, not a pure compound, and from the perspective of its preparation method, it is also impossible to generate a layered structure because sufficient Na is not provided during its preparation process. + The layered structure used to support phosphates leads to the fact that the adsorption mechanism is mainly physical adsorption produced by the mesoporous structure of phosphates, so its adsorption to radionuclides (Cs + , Sr 2+ and Co 2+ ) does not have a large adsorption capacity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a layered phosphate material for radionuclide adsorption with high adsorption capacity and fast adsorption speed, as well as its preparation method and application. The layered phosphate adsorbent structure of the present invention contains monovalent filling ions, such as H + , Na + , K + , so that it can be used with the monovalent Cs + Ion exchange can also be used to treat divalent Sr 2+ and Co 2+ For adsorption.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A layered phosphate material for radionuclide adsorption is provided. The material is a layered phosphate X3HY(PO4)2 with a Glaserite-type structure, wherein X=Na and Y=Mg or Ca.

[0008] The method for preparing the layered phosphate material for radionuclide adsorption comprises the following steps:

[0009] S1: adding an alkaline hydroxide or magnesium salt, a sodium salt and a sodium phosphate salt in a molar ratio of 1:1-3:1-10 into deionized water and stirring and mixing them uniformly; wherein the alkaline hydroxide is Mg(OH)2 or Ca(OH)2, the magnesium salt is MgCl2 or Mg(NO3)2; the sodium salt is NaCl or NaNO3; and the phosphate is NaH2PO4 or Na3PO4;

[0010] S2: Pour the material obtained after evenly mixing S1 into a high-temperature reactor, place the high-temperature reactor in a closed oven, heat it to 100-200°C, react at a constant temperature for 1-24 hours, and then cool it to room temperature to obtain the resulting layered phosphate material;

[0011] Furthermore, the product in S2 is taken out, washed with deionized water and ethanol, and centrifuged, and then placed in a vacuum oven for drying.

[0012] Furthermore, the cleaning times are 2 to 5 times.

[0013] Furthermore, the centrifugal speed is 3000-10000 rpm / min, and the centrifugal time is 5-10 min.

[0014] The present invention also provides the application of the layered phosphate material to treat radioactive wastewater, which can be used in a wide pH range (Cs + :3~11; Sr 2+ :3~9; Co 2+ :3~7) to achieve efficient removal of radioactive ions in water.

[0015] The layered phosphate material of the present invention can also treat radioactive wastewater containing interfering ions, including Na + , K + , Mg 2+ , Ca 2+ One or more of the .

[0016] Compared with the prior art, the present invention has the following benefits:

[0017] (1) The present invention uses alkaline hydroxide or magnesium salt and sodium phosphate as raw materials, reacts in a high temperature and high pressure reactor to generate a layered phosphate X3HY(PO4)2 (X = Na; Y = Mg, Ca) of Glaserite type structure. The obtained adsorbent material has a small particle size and is therefore particularly suitable for adsorbing radioactive nuclide ions such as in solution. 137 Cs, 90 Sr and 60 Co.

[0018] (2) The present invention provides a method for preparing a radioactive nuclide material capable of being adsorbed, wherein a layered phosphate material such as Na3HMg(PO4)2 is obtained by hydrothermal synthesis of Mg(OH)2, NaCl and Na2HPO4, and the atoms thereof are rearranged to form a stable structure, and the interlayer ions (Na + , H + ) and the layer ions (Mg 2+ ) can exchange with radionuclides, thereby increasing their adsorption properties.

[0019] (3) The present invention provides a method for preparing an adsorbable radionuclide material, which can be prepared by ion exchange and dissolution and reprecipitation (such as Cs + and interlayer Na + and H + Ion exchange and Mg 2+ and PO4 3- Combined to form a precipitate Cs[Mg(H2O)6]PO4; Sr 2+ With Mg 2+ Ion exchange and PO4 3- Combined to form a precipitate (Sr 0.95 Mg 0.05 )3(PO4)2;Co 2+ With Mg 2+ Ion exchange and PO4 3- Combined to form a precipitate Co3(PO4)2∙8H2O) to form a stable compound, making the material resistant to radionuclides 137 Cs, 90 Sr and 60 Co has adsorptive properties.

[0020] (4) The present invention is a radioactive nuclide adsorbable material, which can 137 Cs, 90 Sr and 60 Co has a large adsorption capacity and a high degree of applicability.

[0021] (5) The application of the radioactive nuclide adsorption material provided by the present invention in treating radioactive wastewater can be carried out in a wide pH range (Cs + :3~11; Sr 2+ :3~9; Co 2+ :3~7) to achieve efficient removal of radioactive ions in water.

[0022] (6) The preparation method of the present invention is simple and economical, the material is easy to prepare, and can be widely used. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of the layered phosphate adsorption material Na3HMg(PO4)2 in Example 1;

[0024] Figure 2 is a SEM image of the layered phosphate adsorbent material Na3HMg(PO4)2 in Example 1;

[0025] Figure 3 is the XRD pattern of the layered phosphate adsorbent material Na3HMg(PO4)2 in Example 1;

[0026] Figure 4 is the FTIR graph of the layered phosphate adsorbent material Na3HMg(PO4)2 in Example 1;

[0027] Figure 5 is a schematic structural diagram of the layered phosphate adsorption material K3HCa(PO4)2 in Example 2;

[0028] Figure 6 The layered phosphate adsorption material Na3HMg(PO4)2 in Example 1 adsorbs Cs + , Sr 2+ and Co 2+ After the SEM image;

[0029] Figure 7 The layered phosphate adsorption material Na3HMg(PO4 ) 2 adsorption of Cs + , Sr 2+ and Co 2+ After the XRD pattern;

[0030] Figure 8 The layered phosphate adsorption material Na3HMg(PO4)2 in Example 1 adsorbs radionuclides and Cs + , Sr 2+ and Co 2+ kinetic diagram. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute any limitation to the scope of protection of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other, and the resulting technical solutions are also considered to fall within the contents disclosed in the embodiments of the present application.

[0032] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art.

[0033] Unless otherwise specified, the reagents and materials used in the following examples were commercially available and of analytical grade. Example 1

[0034] A preparation method of a layered phosphate adsorbent, the preparation method is as follows:

[0035] Preparation of Na3HMg(PO4)2: Mg(OH)2, NaCl and Na2HPO4 were added to deionized water in a molar ratio of 1:1:8, stirred evenly, and placed in a polytetrafluoroethylene-lined autoclave for reaction at a constant temperature of 150°C for 24 hours. The product was washed twice with deionized water and ethanol in sequence. After each washing, it was centrifuged at a speed of 5000 rpm / min for 5 minutes and then vacuum dried for 24 hours to obtain the layered phosphate material - white powder solid Na3HMg(PO4)2. Its structural schematic is shown in FIG. Figure 1 , three oxygen atoms of the PO4 tetrahedron are shared with the adjacent MgO6 octahedron, one oxygen atom is a non-bridging bond, and the [Mg(PO4)2] layer exhibits a negative charge, forming a looser stacking structure with additional compensating cations, allowing additional cationic positions in the stacking of the layers, whose vacancies are occupied by Na and H.

[0036] The adsorbent, Na3HMg(PO4)2, was analyzed by scanning electron microscopy (SEM). Figure 2 As shown, the adsorbent is nanoparticles with a particle size of about 50 nm.

[0037] The adsorbent, Na3HMg(PO4)2, was subjected to X-ray diffraction (XRD) analysis, and the results were as follows: Figure 3 As shown, the corresponding ICDD card number is 01-086-0528, proving that the Na3HMg(PO4)2 material was successfully synthesized.

[0038] The adsorbent, Na3HMg(PO4)2, was analyzed by infrared spectroscopy (FTIR). The results are as follows: Figure 4 As shown in the figure, it can be seen that at 546cm-1 and 1067cm -1 The characteristic peak at is attributed to PO4 3- vibration, and 3300 to 3700cm -1 The peak at is attributed to the presence of water molecules.

[0039] Effect experiment

[0040] 1. Adsorption experiment:

[0041] The layered phosphate adsorption material Na3HMg(PO4)2 prepared in Example 1 was used to remove simulated radionuclides from water. 137 Cs, 90 Sr and 60 Co, the steps are as follows: use a 30mL reagent bottle as a reactor, add 20mL of the simulated nuclide Cs into the reactor + , Sr 2+ and Co 2+ The reactor was sealed and placed in a desktop oscillator at a speed of 150 rpm and a temperature of 25°C.

[0042] Detection method: After the solution was filtered through a 0.22 μm microporous membrane, the initial and residual Cs were detected by flame atomic absorption spectrometry (FAAS). + , Sr 2+ and Co 2+ The adsorption results are shown in the following table:

[0043]

[0044] As can be seen from the table above, the layered phosphate adsorbent obtained in Example 1 has a high adsorption capacity for radioactive nuclides. Under the condition of an initial concentration of about 1000 mg / L, the layered phosphate adsorbent has a high adsorption capacity for Cs + The maximum adsorption capacity of Sr is 399.66 mg / g. 2+ The maximum adsorption capacity of Co is 444.85 mg / g. 2+ The maximum adsorption capacity is 441.92 mg / g.

[0045] The adsorbed material was measured by SEM, where Cs + The results are as follows Figure 6 As shown in (a), Sr 2+ The results are as follows Figure 6 As shown in (b), Co 2+ The results are as follows Figure 6 (c) As shown in the figure, it can be seen that the material adsorbs Cs + Then a tetrahedral structure with a diameter of 2-5 μm is generated, which adsorbs Sr 2+Then the particles with a diameter of about 2 μm are generated, which adsorb Co 2+ Then a flower-like flake stacking structure with a diameter of about 5 μm is generated.

[0046] The adsorbed material was measured by XRD, where Cs + The results are as follows Figure 7 As shown in (a), Sr 2+ The results are as follows Figure 7 As shown in (b), Co 2+ The results are as follows Figure 7 As shown in (c), it can be seen from the figure that the XRD of the material after adsorption has changed, and the product and the corresponding ICDD card number are Cs[Mg(H2O)6]PO4:96-201-3392, (Sr 0.95 Mg 0.05 )3(PO4)2: 00-014-0491, Co3(PO4)2∙8H2O: 00-041-0375.

[0047] 2. Anti-interference experiment under different pH conditions

[0048] The anti-interference test of the layered phosphate adsorbent Na3HMg(PO4)2 prepared in Example 1 on the adsorption of radionuclides under different pH conditions:

[0049] Formulated with Cs + The initial concentration of the solution was 100 mg / L, and the Cs + The pH value of the solution was adjusted to 3, 5, 7, 9, and 11. The adsorbent was placed in a reagent bottle containing 20 mL of the solution. The adsorbent dosage was 1 g / L, the adsorption temperature was T = 25 °C, the adsorption time was t = 24 h, and the speed of the desktop oscillator was 150 rpm / min. The Cs in the adsorbed solution was then determined by atomic absorption spectrometry. + concentration.

[0050] Preparation containing Sr 2+ The initial concentration of the solution was 100 mg / L, and the Cs + The pH value of the solution was adjusted to 3, 5, 7, 9, and 11. The adsorbent was placed in a reagent bottle containing 20 mL of the solution. The adsorbent dosage was 1 g / L, the adsorption temperature was T = 25 °C, the adsorption time was t = 24 h, and the speed of the desktop oscillator was 150 rpm / min. The Sr content in the adsorbed solution was then determined by atomic absorption spectrometry. 2+ concentration.

[0051] Formulated with Co 2+ The initial concentration of the solution was 100 mg / L, and the Co 2+The pH value of the solution was adjusted to 3, 5, and 7. The adsorbent was placed in a reagent bottle containing 20 mL of the solution. The adsorbent dosage was 1 g / L, the adsorption temperature was T = 25 ° C, the adsorption time was t = 24 h, and the speed of the desktop oscillator was 150 rpm / min. The Co in the adsorbed solution was then determined by atomic absorption spectrometry. 2+ The results are shown in the following table:

[0052]

[0053] It can be seen from the above table that the prepared layered phosphate adsorbent can be used in a wide pH range (Cs + :3~11; Sr 2+ :3~9; Co 2+ :3~7) to achieve efficient removal of radioactive ions in water.

[0054] 3. Anti-interference test of different coexisting ions

[0055] The anti-interference test of the layered phosphate adsorbent Na3HMg(PO4)2 prepared in Example 1 against different coexisting ions:

[0056] Prepare Cs solution with a concentration of 200 mg / L at pH = 7 and T = 25°C. + With 100mmol / L Na + , K + , Mg 2 + , Ca 2+ The adsorbent was added to 20 mL of the solution with the coexistence of interfering ions. The addition amount was 1 g / L. The adsorption time was t = 30 min. The speed of the desktop oscillator was 150 rpm / min. Then the Cs in the solution was determined by atomic absorption spectrometry. + concentration.

[0057] Prepare Sr with a concentration of 400 mg / L at pH = 7 and T = 25°C. 2+ With 100mmol / L Na + , K + , Mg 2 + , Ca 2+ The adsorbent was added to 20 mL of the solution with the coexistence of interfering ions. The addition amount was 1 g / L. The adsorption time was t = 1440 min. The speed of the desktop oscillator was 150 rpm / min. Then the Sr in the solution was determined by atomic absorption spectrometry. 2+ concentration.

[0058] Prepare a 200 mg / L Co solution at pH = 7 and T = 25°C. 2+With 100mmol / L Na + , K + , Mg 2 + , Ca 2+ The adsorbent was added to 20 mL of the solution with the coexistence of interfering ions. The addition amount was 1 g / L. The adsorption time was t = 480 min. The speed of the desktop oscillator was 150 rpm / min. Then the Co in the solution was determined by atomic absorption spectrometry. 2+ concentration.

[0059] Under the conditions of pH=7, T=25℃, simulated seawater (Na + :9670 mg / L; K + :367.6 mg / L; Mg 2+ :1110mg / L;Ca 2+ :331.6 mg / L): Based on simulated seawater, Cs was added + 、Sr 2+ and Co 2+ , so that their concentrations were 0.4mmol / L respectively; the layered phosphate adsorbent material was added to 20mL of simulated seawater, the addition amount was 1g / L, the adsorption time was t=1440min (24h), the desktop oscillator speed was 150rpm / min, and the Cs + , Sr 2+ and Co 2+ The adsorption results are shown in Table 3.

[0060] The adsorption results are shown in the following table:

[0061]

[0062] It can be seen from the above table that the prepared layered phosphate adsorbent has good anti-ion interference ability, especially for Cs + and C O 2+ The adsorption of Na + , K + Mg 2+ It still has good adsorption capacity when coexisting alone. In the complex seawater environment, the adsorbent has good adsorption capacity for Cs + , Sr 2+ and Co 2+ It also has adsorption capacity.

[0063] Comparison of the affinity of the layered phosphate adsorbent Na3HMg(PO4)2 prepared in Example 1 to Cs, Sr and Co ions:

[0064] Prepare Cs solution with a concentration of 0.4 mmol / L at pH = 7 and T = 25°C. + With Sr 2+ The mixture of 0.4mmol / L Cs + With Co 2+ The mixture of 0.4mmol / L Sr 2+ With Co 2+ The adsorbent was added to 20 mL of the three ion mixture at a dosage of 1 g / L. The adsorption time was t = 1440 min (24 h). The speed of the desktop oscillator was 150 rpm / min. Then, the Cs in the solution was determined by atomic absorption spectrometry. + , Sr 2+ With Co 2+ Concentration and distribution coefficient ( K d ), and calculate the separation coefficient ( K d / K d ).

[0065] The adsorption results are shown in the following table:

[0066]

[0067] As can be seen from the table above, in Cs + , Sr 2+ and Co 2+ Under the coexistence conditions, the affinity of the layered phosphate adsorbent to the three ions is in the following order: Co 2+ >Sr 2+ >Cs + .

[0068] 4. Adsorption rate experiment

[0069] Example 1 provides the adsorption rate of radionuclides by the layered phosphate adsorbent Na3HMg(PO4)2:

[0070] Prepare Cs solution with a concentration of 1000 mg / L at pH = 7 and T = 25°C. + The adsorbent was added to 20 mL of the solution at a dosage of 1 g / L. The Cs in the solution was measured by atomic absorption spectrometry at 5 min, 10 min, 20 min, 30 min, 60 min, 120 min, 240 min, 480 min, 720 min, and 1440 min. + Concentration, the results are as follows Figure 8 As shown in (a), the reaction reached adsorption equilibrium in 30 min.

[0071] Prepare Sr with a concentration of 1000 mg / L at pH = 7 and T = 25°C. 2+ The adsorbent was added to 20 mL of the solution at a dosage of 1 g / L. The Sr content in the solution was measured by atomic absorption spectrometry at 5 min, 10 min, 20 min, 30 min, 60 min, 120 min, 240 min, 480 min, 720 min, and 1440 min. 2+ Concentration, the results are as follows Figure 8 As shown in (b), the reaction reached adsorption equilibrium at 1440 min.

[0072] Prepare a 1000 mg / L Co2 solution at pH = 7 and T = 25°C. + The adsorbent was added to 20 mL of the solution at a dosage of 1 g / L. The concentration of Co in the solution was measured by atomic absorption spectrometry at 5 min, 10 min, 20 min, 30 min, 60 min, 120 min, 240 min, 480 min, 720 min, and 1440 min. 2+ Concentration, the results are as follows Figure 8 As shown in (c), the reaction reached adsorption equilibrium at 240 min.

[0073] Example 2

[0074] Synthesis of Mg-Na-PO4 phosphate adsorbent: Mg(NO3)2, NaNO3 and Na2HPO4 were added to deionized water in a molar ratio of 1:1:8, stirred evenly, placed in a polytetrafluoroethylene-lined high-pressure reactor, and reacted at a constant temperature of 150°C for 24 hours. The product was washed twice with deionized water and ethanol in sequence. After each washing, it was centrifuged at a speed of 5000 rpm / min for 5 minutes, then vacuum dried for 24 hours, and ground to obtain a powdered solid, which is the phosphate adsorbent.

[0075] Example 3

[0076] Synthesis of Mg-Na-PO4 phosphate adsorbent: MgCl2, NaCl and Na2HPO4 were added to deionized water in a molar ratio of 1:1:1, stirred evenly, placed in a polytetrafluoroethylene-lined high-pressure reactor, and reacted at a constant temperature of 100°C for 1 hour. The product was washed three times with deionized water and ethanol in sequence. After each washing, it was centrifuged at a speed of 3000 rpm / min for 10 minutes, and then vacuum dried for 24 hours. The powdered solid was ground to obtain the phosphate adsorbent.

[0077] Example 4

[0078] Synthesis of Mg-Na-PO4 phosphate adsorbent: Mg(OH)2, NaCl and Na3PO4 were added to deionized water in a molar ratio of 1:1:10, stirred evenly, placed in a polytetrafluoroethylene-lined high-pressure reactor, and reacted at a constant temperature of 200°C for 24 hours. The product was washed with deionized water and ethanol five times in sequence. After each washing, it was centrifuged at a speed of 10,000 rpm / min for 5 minutes, then vacuum dried for 24 hours, and ground to obtain a powdered solid, which is the phosphate adsorbent.

[0079] Comparative Example 1

[0080] Synthesis of Mg-Na-PO4 phosphate adsorbent: Mg(OH)2, NaCl and (NH4)2HPO4 were added to deionized water in a molar ratio of 1:1:8, stirred evenly, placed in a polytetrafluoroethylene-lined high-pressure reactor, and reacted at a constant temperature of 150°C for 24 hours. The product was washed twice with deionized water and ethanol in sequence. After each washing, it was centrifuged at a speed of 5000 rpm / min for 5 minutes, then vacuum dried for 24 hours, and ground to obtain a powdered solid, which is the phosphate adsorbent.

[0081] Comparative Example 2

[0082] Synthesis of Mg-Na-PO4 phosphate adsorbent: Mg(OH)2, NaCl and K2HPO4 were added to deionized water in a molar ratio of 1:1:8, stirred evenly, placed in a polytetrafluoroethylene-lined high-pressure reactor, and reacted at a constant temperature of 150°C for 24 hours. The product was washed twice with deionized water and ethanol in sequence. After each washing, it was centrifuged at a speed of 5000 rpm / min for 5 minutes, then vacuum dried for 24 hours, and ground to obtain a powdered solid, which is the phosphate adsorbent.

[0083] Comparative Example 3

[0084] Synthesis of Ca-Na-PO4 phosphate adsorbent: Ca(OH)2, NaCl and Na2HPO4 are added to deionized water in a molar ratio of 1:1:8, stirred evenly, placed in a polytetrafluoroethylene-lined high-pressure reactor, and reacted at a constant temperature of 150°C for 24 hours. The product is washed twice with deionized water and ethanol in sequence. After each washing, it is centrifuged at a speed of 5000 rpm / min for 5 minutes, then vacuum-dried for 24 hours, and ground to obtain a powdered solid, which is the phosphate adsorbent.

[0085] Comparative Example 4

[0086] Preparation of K3HCa(PO4)2: Ca(OH)2, KCl and K2HPO4 were added to deionized water in a molar ratio of 1:1:8, stirred evenly, and placed in a polytetrafluoroethylene-lined autoclave for reaction at a constant temperature of 150°C for 24 hours. The mixture was washed twice with deionized water and ethanol in sequence. After each washing, the mixture was centrifuged at a speed of 5000 rpm / min for 5 minutes and vacuum dried for 24 hours to obtain the layered phosphate material - white powdery solid K3HCa(PO4)2. The schematic diagram of its structure is shown in FIG. Figure 5 As can be seen from the figure, three oxygen atoms of the PO4 tetrahedron are shared with the adjacent CaO6 octahedron, one oxygen atom is a non-bridging bond, and the [Ca(PO4)2] layer exhibits a negative charge, forming a looser stacking structure with additional compensating cations, allowing additional cationic positions in the stacking of the layers, whose vacancies are occupied by K and H.

[0087]

[0088] As can be seen from the above table, in Examples 2-4, different magnesium salts, sodium salts and sodium phosphate salts are used to react, and the resulting adsorbents have good adsorption effects on radioactive elements.

[0089] In Comparative Example 1, (NH4)2HPO4 replaced Na2HPO4 in Example 1, while other conditions remained unchanged, and the adsorption amount was greatly reduced.

[0090] In Comparative Example 2, K2HPO4 replaced Na2HPO4 in Example 1, while other conditions remained unchanged, and the adsorption amount was greatly reduced.

[0091] In Comparative Example 3, Ca(OH)2 replaced Mg(OH)2 in Example 1, while other conditions remained unchanged, and the adsorption amount was greatly reduced.

[0092] Comparative Example 4: K3HCa(PO4)2 was synthesized by pressing Ca(OH)2, KCl and K2HPO4. Although it also belongs to the layered phosphate of Glaserite structure, it has a strong affinity for Sr 2+ and Co 2+ Has adsorption properties, for Cs + The adsorption capacity is very low.

[0093] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A layered phosphate material for radionuclide adsorption, characterized in that: The material is a layered phosphate X3HY(PO4)2 with a Glaserite-type structure, wherein X=Na; Y=Mg; The material is prepared by the following method: S1: adding an alkaline hydroxide or magnesium salt, a sodium salt and a sodium phosphate salt in a molar ratio into deionized water and stirring and mixing them uniformly; the alkaline hydroxide is Mg(OH)2, the magnesium salt is MgCl2 or Mg(NO3)2; the sodium salt is NaCl or NaNO3; the phosphate is Na2HPO4 or Na3PO4; S2: Pour the material obtained in S1 into a high-temperature reactor, place the high-temperature reactor in a closed oven, and react at a constant temperature of 100-200°C for 1-24 hours, and then cool to room temperature to obtain a layered phosphate material.

2. A method for preparing a layered phosphate material for radionuclide adsorption according to claim 1, characterized in that: The following steps are involved: S1: adding alkaline hydroxide or magnesium salt, sodium salt and sodium phosphate in a molar ratio into deionized water and stirring to mix evenly; S2: Pour the material obtained in S1 into a high-temperature reactor, place the high-temperature reactor in a closed oven, and react at a constant temperature of 100-200°C for 1-24 hours, and then cool to room temperature to obtain a layered phosphate material.

3. The method for preparing a layered phosphate material for radionuclide adsorption according to claim 2, characterized in that: In step S1, the molar ratio of the alkaline hydroxide or magnesium salt to the sodium phosphate salt is 1:1-10.

4. The method for preparing a layered phosphate material for radionuclide adsorption according to claim 2, characterized in that: In step S1, the amount of sodium salt added is: the molar ratio of alkaline hydroxide or magnesium salt to sodium salt is 1:1-3.

5. The method for preparing a layered phosphate material for radionuclide adsorption according to claim 2, characterized in that: The layered phosphate material obtained in step S2 is further washed, centrifuged, and dried.

6. The method for preparing a layered phosphate material for radionuclide adsorption according to claim 5, characterized in that: The cleaning is performed with deionized water and ethanol for multiple times, with the number of cleaning times being 2 to 5 times; the centrifugal speed is 3000 to 10000 rpm / min, and the centrifugal time is 5 to 10 minutes.

7. Use of the layered phosphate material for radionuclide adsorption according to claim 1 for treating radioactive wastewater.

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