Prussian blue composite adsorbent for selectively extracting cesium and preparation method and application thereof

Abstract

The application discloses a Prussian blue composite adsorbent for selectively extracting cesium and a preparation method and application thereof. The preparation steps of the composite adsorbent comprise the following steps: uniformly mixing polyethylene glycol, a ferric salt and a solvent, stirring to form a complex of the polyethylene glycol and the ferric ion, then adding a high polymer material into the complex, uniformly mixing, vacuum deaerating, and then preparing a high polymer microsphere precursor with a hollow structure through spray drying; mixing the high polymer microsphere precursor with a potassium ferrocyanide solution to react, and then filtering, washing with water and drying to obtain the Prussian blue composite adsorbent for selectively extracting cesium. The composite adsorbent has the characteristics of high Prussian blue loading capacity, high adsorption capacity and low loss, and can be applied to extraction of cesium elements in cesium-containing solutions such as salt lake raw brine, old brine, lithium precipitation mother liquor, seawater and underground water resources.

Description

TECHNICAL FIELD

[0001] The present application relates to a hollow structure of polymer / prussian blue composite adsorbent and its preparation method and application, belonging to the technical field of cesium extraction in brine resources. BACKGROUND

[0002] Cesium is a rare metal element with unique properties. It has great development in traditional application fields such as electronic devices, catalysts, special glass, biochemistry and medicine. At the same time, it also shows strong vitality in emerging fields such as cesium ion cloud communication, magnetic fluid power generation, laser energy conversion power generation device, etc. In China, cesium resources are mainly extracted from cesium spar and lithium mica ore. Acid method, alkali method, iron chloride, BAMBP extraction method, etc. are often used in production. However, the development of cesium resources in ore requires the use of various chemical reagents, which has poor environmental friendliness. In recent years, with the rapid development of salt lake lithium extraction technology, the resources of rubidium and cesium associated in brine have attracted widespread attention. Extraction of cesium element from extremely low concentration brine has also become a new research hotspot.

[0003] The extraction of cesium resources in salt lake brine often uses adsorption method. Prussian blue and its analogues have good adsorption performance for cesium ions in water, and the preparation method is simple, economical and has high selectivity. As a cesium ion adsorbent, it has become the focus of researchers. However, prussian blue usually exists in the form of microcrystals, which is easy to lose in actual use. At the same time, prussian blue has poor solubility in most solvents, and the reaction rate is fast during preparation, which limits the application of prussian blue adsorbent.

[0004] In view of the above problems, composite adsorbents with prussian blue as active material have gradually attracted attention. The invention patent WO2019134183A1 uses particulate inorganic oxides or activated carbon as carrier, and the outer periphery is wrapped with ferrocyanide layer, and the outermost periphery is coated with a layer of polymer material. The prepared composite adsorbent has high strength and high stability, and can be produced on a large scale. The invention patent CN105233794B uses carbon fiber / graphene composite material as carrier, and then deposits prussian blue on it. The prepared composite adsorbent has excellent selective adsorption capacity, and is easy to operate and separate. The invention patent CN113509910B uses water-absorbing polymer as carrier, mixes with metal ferrocyanide powder, and then extrudes and granulates after secondary crosslinking. The adsorbent particles have high elasticity, porosity, high water absorption, good permeability and other characteristics. However, the prussian blue composite adsorbents disclosed in these patents have the problems of complex preparation process, high proportion of carrier material in the composite adsorbent, and the properties of the carrier material limiting the application of the composite adsorbent. In addition, the carrier material usually does not have high pore structure, which is not conducive to the transmission of molecules on the surface or inside in actual application, and the adsorption capacity cannot be further improved. SUMMARY

[0005] In view of the deficiencies of the prior art, the application provides a Prussian blue composite adsorbent for selectively extracting cesium, which is prepared by using a hollow-structured polymer microsphere as a carrier, using a complex of polyethylene glycol (PEG) and trivalent iron ions as a pore-forming agent, and loading a large amount of Prussian blue adsorption material on the surface and inside of the carrier in situ to obtain a hollow-structured polymer / Prussian blue composite adsorbent. The prepared adsorbent not only has the characteristics of acid resistance, alkali resistance and chemical stability, but also has the advantages of a large specific surface area, a developed internal pore structure, high stability, high loading capacity, and the active component is not easy to be lost.

[0006] The Prussian blue composite adsorbent for selectively extracting cesium can be widely used in the extraction of cesium elements in cesium-containing solutions such as salt lake crude brine, old brine, lithium precipitation mother liquor, seawater and groundwater resources, and can effectively improve the cesium adsorption efficiency and service life.

[0007] To achieve the above object, the technical scheme adopted by the application is as follows:

[0008] Firstly, the application provides a preparation method of a Prussian blue composite adsorbent for selectively extracting cesium, which comprises the following steps:

[0009] (1) uniformly mixing polyethylene glycol, trivalent iron salt and a solvent to form a complex of polyethylene glycol and trivalent iron ions, then adding a polymer material thereto, uniformly mixing, vacuum degassing, and then preparing a polymer microsphere precursor by spray drying;

[0010] (2) mixing the polymer microsphere precursor with a potassium ferrocyanide solution to react, and then filtering, washing with water and drying to obtain the Prussian blue composite adsorbent for selectively extracting cesium.

[0011] In some specific examples, the molecular weight of the polyethylene glycol in step (1) is 400-2000, for example, 400, 800, 1000, 1500 or 2000, preferably 400-1000.

[0012] Preferably, the amount of polyethylene glycol is 10-25wt%, for example, 10wt%, 15wt%, 20wt% or 25wt%, more preferably 15-20wt%, based on the total mass of polyethylene glycol, trivalent iron salt, solvent and polymer material being 100%.

[0013] In some specific examples, the trivalent iron salt in step (1) is selected from one or more of ferric nitrate, ferric chloride, ferric sulfate, ferric acetate or a hydrate thereof.

[0014] Preferably, the ferric salt is used in an amount of 2-10 wt%, such as 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, more preferably 5-9 wt%, based on the total mass of the polyethylene glycol, ferric salt, solvent and high molecular material being 100%.

[0015] In some specific examples, the solvent in step (1) is selected from one or more of amides, halogenated hydrocarbons, ketones, sulfones, preferably one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane, dichloroethane, acetone, dioxane, dimethyl sulfoxide;

[0016] Preferably, the solvent is used in an amount of 60-85 wt%, such as 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, more preferably 65-80 wt%, based on the total mass of the polyethylene glycol, ferric salt, solvent and high molecular material being 100%.

[0017] In some specific examples, the high molecular material in step (1) is selected from conventional raw materials that can be used to prepare high molecular film materials in the art, preferably one or more of polysulfones, fluoropolymers, cellulose derivatives, ethylene polymers;

[0018] Preferably, the high molecular material has a molecular weight of 5-100 million, such as 5 million, 20 million, 40 million, 60 million, 80 million, 100 million, more preferably one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, cellulose acetate, polyvinyl chloride;

[0019] Preferably, the high molecular material is used in an amount of 2.5-15 wt%, such as 2.5 wt%, 5.0 wt%, 7.5 wt%, 10.0 wt%, 12.5 wt%, 15.0 wt%, based on the total mass of the polyethylene glycol, ferric salt, solvent and high molecular material being 100%.

[0020] In some specific examples, the stirring in step (1) forms a complex of polyethylene glycol and ferric ion, specifically through complexation reaction of ferric ion and the polyhydroxy groups in PEG to form a complex with stable mono- to tri-coordination structure, which becomes a pore-forming agent for high molecular microspheres in subsequent reactions, wherein the stirring time is 12-24 h, such as 12 h, 16 h, 20 h, 24 h;

[0021] Preferably, the end point of the stirring is the change from brownish red to brown in color of the solution, which indicates that the complex of polyethylene glycol and ferric ion is formed.

[0022] In some specific examples, the vacuum degassing in step (1) is performed at a pressure of 0.5-1.5 MPaG, such as 0.5 MPaG, 0.8 MPaG, 1.1 MPaG, 1.5 MPaG, and for a time period of 6-24 h, such as 6 h, 10 h, 14 h, 18 h, 22 h, 24 h.

[0023] In some specific examples, the spray drying in step (1) is performed at a temperature of 80-250℃, such as 80℃, 100℃, 125℃, 150℃, 175℃, 200℃, 225℃, 250℃, preferably 200-235℃.

[0024] Preferably, the spray drying is performed using a nozzle with a diameter of 0.05-1 mm, such as 0.05, 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, 1 mm.

[0025] Under the spray drying conditions of the present application, the mixed solution is first atomized into small droplets, and upon entering the drying chamber, the solvent in the droplets rapidly evaporates. Due to the fact that the internal vapor pressure is greater than the external vapor pressure, the polymer is precipitated and continuously expands during the internal solvent evaporation process, and finally forms polymer microspheres with hollow structure, and at the same time contains the complex of PEG and ferric ion on the surface and inside thereof.

[0026] In some specific examples, the potassium ferrocyanide solution in step (2) is an aqueous solution of potassium ferrocyanide with a concentration of 0.1-5 wt%, such as 0.1 wt%, 0.5 wt%, 1.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, preferably 0.5-2 wt%.

[0027] In some specific examples, the mixing mass ratio of the polymer microsphere precursor to the potassium ferrocyanide solution in step (2) is 1:1-10, such as 1:1, 1:3, 1:5, 1:7, 1:9, 1:10, preferably 1:1-2.5.

[0028] In some specific examples, the reaction in step (2) is performed at a temperature of 100-150℃, such as 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, preferably 120-140℃, and for a time period of 1-12 h, such as 1 h, 3 h, 5 h, 7 h, 9 h, 11 h, 12 h, preferably 6-10 h. During the reaction, the complex of PEG and ferric ion becomes a pore-forming agent for the polymer microspheres, which partially and slowly dissolves and diffuses in the potassium ferrocyanide solution, resulting in the formation of microporous structure on the surface of the microspheres; and the interaction between PEG and the polymer inhibits the slow release of ferric ion, thereby controlling the nucleation and growth rate of Prussian blue, and finally forming Prussian blue particles in situ on the surface and inside of the microspheres.

[0029] In some specific examples, the filtration, washing, and drying described in step (2) are routine operations in the art, and the present invention does not have any special requirements. Since the composite adsorbent obtained after the reaction in step (4) may have residual solvent on its surface and inside, as well as complexes formed by PEG and ferric ions that did not participate in the reaction, it is necessary to repeatedly wash, filter, and dry it with pure water to finally obtain a stable, hollow-structured polymer / Prussian blue composite adsorbent material.

[0030] Secondly, the present invention also provides a Prussian blue composite adsorbent for selectively extracting cesium prepared by the above method.

[0031] The selective cesium-extracting Prussian blue composite adsorbent uses hollow polymer microspheres as a carrier and a complex of polyethylene glycol and ferric ions as a pore-forming agent. The resulting microspheres exhibit a rich microporous structure on their surface. By further controlling the nucleation and growth of Prussian blue through PEG, Prussian blue particles can be grown in situ on the surface and inside of the microspheres.

[0032] In some specific examples, the total mass of the Prussian blue composite adsorbent for selectively extracting cesium is based on the Prussian blue content of 25-65 wt%, for example, 25 wt%, 35 wt%, 45 wt%, 55 wt%, 65 wt%, preferably 35-65 wt%.

[0033] In some specific examples, the Prussian blue composite adsorbent for selectively extracting cesium has a particle size of 0.05-1 mm, such as 0.05 mm, 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, and 1 mm.

[0034] In some specific examples, the Prussian blue composite adsorbent for selectively extracting cesium has a specific surface area of ​​500-1000 m². 2 / g for example 500m 2 / g、550m 2 / g 600m 2 / g、650m 2 / g、700m 2 / g、750m 2 800m 2 / g、850m 2 / g、900m 2 / g、950m 2 / g, 1000m 2 / g, preferably 650-900m 2 / g, with a porosity of 58-80%, for example 58%, 60%, 65%, 70%, 75%, 80%, preferably 60-80%.

[0035] Finally, the present invention also provides the application of the Prussian blue composite adsorbent for selectively extracting cesium.

[0036] The composite adsorbent described in this invention can be used for the extraction of cesium from cesium-containing solutions;

[0037] Preferably, the cesium-containing solution can be raw brine from a salt lake, old brine, lithium precipitation mother liquor, seawater, or groundwater resources.

[0038] The composite adsorbent described in this invention is widely applicable to the extraction of cesium from cesium-containing solutions of any concentration, and is particularly suitable for the extraction of cesium from cesium-containing solutions with low concentrations. Preferably, the cesium content in the cesium-containing solution can be as low as 0.01-0.05 wt%, for example, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, or 0.05 wt%.

[0039] Compared with modern technology, the advantages of the technical solution of this invention are as follows:

[0040] This invention utilizes a complex of polyethylene glycol and ferric ions as a pore-forming agent to control the nucleation and growth of Prussian blue, resulting in a selective Prussian blue composite adsorbent for cesium extraction. This adsorbent possesses acid and alkali resistance, chemical stability, and structural advantages such as a large specific surface area and a well-developed internal pore structure. Furthermore, due to the in-situ loading of a large amount of Prussian blue adsorbent material on its surface and internal structure, it also exhibits high stability, high loading capacity, and minimal loss of active components. It can be widely applied to the extraction of cesium from cesium-containing solutions such as raw brine, aged brine, lithium precipitation mother liquor, seawater, and groundwater resources, effectively improving cesium adsorption efficiency and service life. Detailed Implementation

[0041] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0042] The main raw material information involved in each embodiment of the present invention is shown in Table 1:

[0043] Table 1 Information on Main Raw Materials

[0044]

[0045]

[0046] Unless otherwise specified, all other raw materials are commercially available industrial-grade standard raw materials.

[0047] The performance test parameters and corresponding test methods in various embodiments of the present invention are as follows:

[0048] The proportion of Prussian blue in the composite adsorbent was determined by elemental analysis.

[0049] Determination of cesium adsorption capacity: 30 mL of the composite adsorbent was added to a 100 mL solution containing cesium ions at a concentration of 200 mg / L, and the mixture was shaken at 25 °C for 8 h for adsorption. The adsorption capacity of the composite adsorbent for cesium was calculated by inductively coupled plasma atomic absorption spectrometry (ICP-MS).

[0050] Adsorbent leaching stability assessment: The composite adsorbent that had adsorbed cesium ion solution was removed and placed in a 50 mL resin column. The adsorbent material was dynamically rinsed with deionized water at a flow rate of 30 mL / h for 3 h to remove residual cesium ion solution from the surface. Then, the adsorbent material was dynamically rinsed with deionized water at a high flow rate of 1 L / h for 20 h. The iron and cesium ion contents in the high-flow-rate effluent were detected by inductively coupled plasma atomic emission spectrometry (ICP-MS).

[0051] The particle size of the adsorbent was determined using the method in GB / T 5758-2001; the specific surface area and porosity were determined using a physical adsorption apparatus.

[0052]

Examples 1-3

[0053] Prussian blue composite adsorbents for selective cesium extraction in Examples 1-3 were prepared according to the raw material formulation and main process conditions in Table 2.

[0054] (1) Mix PEG, ferric salt and solvent evenly, stir for about 12 hours to change the solution from brownish red to brown, forming a complex of polyethylene glycol and ferric ions. Then add polymer material to it, mix evenly, and degas under vacuum at 0.5 MPaG pressure and 25°C for 24 hours. Then spray dry to obtain hollow polymer microsphere precursor.

[0055] (2) The polymer microsphere precursor was mixed with potassium ferrocyanide aqueous solution and reacted. After filtration, rinsing with pure water and drying, Prussian blue composite adsorbent for selective extraction of cesium was obtained.

[0056] Table 2 Raw material formulations and main process conditions for Examples 1-3

[0057]

[0058] Comparative Example 1

[0059] The composite adsorbent was prepared in the same manner as in Example 1, except that in step (1), PEG400, ferric chloride, polysulfone and N,N-dimethylformamide were mixed evenly and stirred for about 2 hours. Then, the mixture was degassed under vacuum at 0.5 MPaG pressure and 25°C for 1 hour, and then spray-dried to obtain a hollow polymer microsphere precursor.

[0060] Comparative Example 2

[0061] The composite adsorbent was prepared in a manner that was essentially the same as in Example 1, except that in step (1), after PEG400, ferric chloride and N,N-dimethylformamide were mixed evenly, a complex was formed without stirring, and polysulfone was added directly to it.

[0062] Comparative Example 3

[0063] The composite adsorbent was prepared in essentially the same manner as in Example 1, except that ferric chloride was not added in step (1).

[0064] Comparative Example 4

[0065] The composite adsorbent was prepared in essentially the same manner as in Example 1, except that in step (1), ferric chloride was replaced with an equal amount of cobalt chloride.

[0066] Comparative Example 5

[0067] The composite adsorbent was prepared in a manner that was essentially the same as in Example 1, except that in step (1), ferric chloride was replaced with an equal amount of ferrous chloride.

[0068] Comparative Example 6

[0069] The composite adsorbent was prepared in essentially the same manner as in Example 1, except that in step (1), PEG400 was replaced with an equal amount of polyethylene oxide (PEO).

[0070] Comparative Example 7

[0071] The composite adsorbent was prepared using essentially the same method as in Example 1, except that potassium ferrocyanide was not added in step (2). The composite adsorbents prepared in the above examples and comparative examples were subjected to performance tests, and the adsorbent leaching stability was evaluated after determining the cesium ion adsorption capacity.

[0072] The cesium-containing solution used to determine the cesium ion adsorption capacity was the lithium sedimentation mother liquor from Zabuye Salt Lake, with a cesium content of 0.02 wt%.

[0073] The evaluation results of the composite adsorbents in each embodiment and comparative example are shown in Table 3.

[0074] Table 3 Evaluation results of the composite adsorbents prepared in the examples and comparative examples.

[0075]

[0076] As shown in Table 3, the iron and cesium ion contents in the effluent of the composite adsorbent prepared in the embodiments of the present invention are both below 1 ppm. This confirms that the adsorbent material provided by the present invention has the characteristics of high Prussian blue loading, high adsorption capacity, and low leaching, and can be applied to the extraction of cesium from salt lake brine, old brine, lithium precipitation mother liquor, seawater, and groundwater resources.

Claims

1. A method for preparing a Prussian blue composite adsorbent for selectively extracting cesium, characterized in that the steps include... include: (1) Polyethylene glycol, ferric salt and solvent are mixed evenly and stirred to form a complex of polyethylene glycol and ferric ions. Then, polymer material is added to it, mixed evenly and vacuum degassed, and then spray dried to obtain polymer microsphere precursor. (2) The polymer microsphere precursor is mixed with potassium ferrocyanide solution and reacted, then filtered, washed with water and dried to obtain the Prussian blue composite adsorbent for selectively extracting cesium.

2. The preparation method according to claim 1, characterized in that, The polyethylene glycol in step (1) has a molecular weight of 400-2000; and / or The ferric salt in step (1) is selected from one or more of ferric nitrate, ferric chloride, ferric sulfate, ferric acetate, or their hydrates; and / or The solvent in step (1) is selected from one or more organic solvents selected from amides, halogenated hydrocarbons, ketones, and sulfones; and / or The polymer material in step (1) is selected from one or more of polysulfones, fluoropolymers, cellulose derivatives, and ethylene polymers.

3. The preparation method according to claim 2, characterized in that, The polyethylene glycol has a molecular weight of 400-1000.

4. The preparation method according to claim 2, characterized in that, The solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane, dichloroethane, acetone, dioxane, and dimethyl sulfoxide.

5. The preparation method according to claim 2, characterized in that, The polymer material has a molecular weight of 50,000 to 1,000,000.

6. The preparation method according to claim 2, characterized in that, The polymer material is selected from one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, cellulose acetate, and polyvinyl chloride.

7. The preparation method according to claim 1, characterized in that, The amount of polyethylene glycol used in step (1) is 10-25 wt%, based on the total mass of polyethylene glycol, ferric salt, solvent and polymer material as 100%.

8. The preparation method according to claim 7, characterized in that, The amount of polyethylene glycol used is 15-20 wt%.

9. The preparation method according to claim 1, characterized in that, The amount of ferric salt used in step (1) is 2-10 wt%, based on the total mass of polyethylene glycol, ferric salt, solvent and polymer material as 100%.

10. The preparation method according to claim 9, characterized in that, The amount of the trivalent iron salt used is 5-9 wt%.

11. The preparation method according to claim 1, characterized in that, The amount of solvent used in step (1) is 60-85 wt%, based on the total mass of polyethylene glycol, ferric salt, solvent and polymer material as 100%.

12. The preparation method according to claim 11, characterized in that, The amount of solvent used is 65-80 wt%.

13. The preparation method according to claim 1, characterized in that, The amount of polymer material used in step (1) is 2.5-15 wt%, based on the total mass of polyethylene glycol, ferric salt, solvent and polymer material being 100%.

14. The preparation method according to claim 1, characterized in that, The stirring in step (1) forms a complex of polyethylene glycol and ferric ions, wherein the stirring time is 12-24 h; and / or The vacuum degassing in step (1) is performed at a pressure of 0.5-1.5 MPaG for a time of 6-24 hours; and / or The spray drying in step (1) is performed at a temperature of 80-250°C. o C.

15. The preparation method according to claim 14, characterized in that, Judging from the color of the solution, the stirring endpoint is a change from brownish-red to brown.

16. The preparation method according to claim 15, characterized in that, The spray drying is performed at a temperature of 200-235°C. o C.

17. The preparation method according to claim 1, characterized in that, The nozzle diameter used in the spray drying step (1) is 0.05-1mm.

18. The preparation method according to claim 1, characterized in that, The potassium ferrocyanide solution mentioned in step (2) is an aqueous solution of potassium ferrocyanide with a concentration of 0.1-5 wt%; and / or In step (2), the mass ratio of the polymer microsphere precursor to the potassium ferrocyanide solution is 1:1-10.

19. The preparation method according to claim 18, characterized in that, The potassium ferrocyanide solution is an aqueous solution of potassium ferrocyanide with a concentration of 0.5-2 wt%.

20. The preparation method according to claim 18, characterized in that, The polymer microsphere precursor and potassium ferrocyanide solution are mixed in a mass ratio of 1:1-2.

5.

21. The preparation method according to claim 1, characterized in that, The reaction described in step (2) is carried out at a temperature of 100-150℃ for 1-12 hours.

22. The preparation method according to claim 21, characterized in that, The reaction is carried out at a temperature of 120-140℃ for 6-10 hours.

23. A Prussian blue composite adsorbent for selectively extracting cesium, prepared by the method according to any one of claims 1-22.

24. The Prussian blue composite adsorbent for selectively extracting cesium according to claim 23, characterized in that, Based on the total mass of the Prussian blue composite adsorbent for selective cesium extraction, wherein the Prussian blue content is 25-65 wt%; and / or The Prussian blue composite adsorbent for selectively extracting cesium has a particle size of 0.05-1 mm; and / or The Prussian blue composite adsorbent for selectively extracting cesium has a specific surface area of ​​500-1000 m². 2 / g, with a porosity of 58-80%.

25. The Prussian blue composite adsorbent for selectively extracting cesium according to claim 24, characterized in that, The total mass of the Prussian blue composite adsorbent for selective cesium extraction is based on the Prussian blue content of 35-65 wt%.

26. The Prussian blue composite adsorbent for selectively extracting cesium according to claim 24, characterized in that, The Prussian blue composite adsorbent for selectively extracting cesium has a specific surface area of ​​650-900 m². 2 / g, with a porosity of 60-80%.

27. The application of the Prussian blue composite adsorbent for selectively extracting cesium prepared by the method of any one of claims 1-22 or the Prussian blue composite adsorbent for selectively extracting cesium according to any one of claims 23-26 in the extraction of cesium from cesium-containing solutions.

28. The application according to claim 27, characterized in that, The cesium-containing solution is a salt lake brine, old brine, lithium precipitation mother liquor, seawater, or groundwater resources.

29. The application according to claim 27, characterized in that, The composite adsorbent is suitable for extracting cesium from cesium-containing solutions of any concentration.

30. The application according to claim 29, characterized in that, The composite adsorbent is suitable for extracting cesium from solutions containing low levels of cesium.

31. The application according to claim 29, characterized in that, The cesium content in the cesium-containing solution is 0.01-0.05 wt%.

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