Adsorbent and its preparation method and application

Abstract

The present invention relates to the technical field of adsorption materials, and discloses an adsorbent, a preparation method thereof, and an application thereof. The structural formula of the adsorbent is as follows; preparation method: after dissolving phloroglucinol, 2,6-dichloropyridine-3,5-dicarbonitrile, and an alkaline catalyst, reacting for 1 h to 1.5 h, the organic layer after extraction is a molecular cage containing a cyano group; under alkaline conditions, dissolving the obtained molecular cage containing a cyano group and hydroxylamine hydrochloride, reacting at 58° C. to 65° C. for 24 h to 48 h, filtering the obtained solid to obtain the adsorbent. The main structure of the adsorbent obtained by the present invention is a molecular cage containing an amide oxime group, and the amide oxime functional group shows great potential as a uranium absorbent due to its selectivity and high chelating affinity for uranium. There are also many electronegative nitrogen and oxygen atoms in the organic structural unit, which can play a synergistic role in the selective adsorption of uranium ions;

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorption materials, and in particular relates to an adsorbent and a preparation method and application thereof. Background Art

[0002] With the ever-increasing demand for energy and the widespread burning of fossil fuels, nuclear energy has long attracted attention as a carbon-free energy source that can significantly alleviate the global energy crisis on a large scale. Among all radionuclides, uranium, as a key basic resource for sustainably enhancing the capabilities of nuclear reactors, plays an indispensable role in the search for alternative energy sources. It is estimated that global seawater contains an almost inexhaustible amount of uranium, approximately 4.5 tons, which is nearly 1,000 times the amount of uranium found on land. Therefore, the development of technologies for selectively extracting uranium seems particularly important. However, the ultra-low concentration of soluble uranium, approximately 3.3 ppb, and the coexistence of a large amount of interfering metal ions pose unprecedented challenges to the recovery of uranium from the ocean. Therefore, how to obtain highly selective and high-adsorption materials for extracting uranium ions from seawater is a technical problem that needs to be solved urgently.

[0003] Prior art discloses a synthesis method and application of a uranyl adsorbent material, as described in Chinese Patent CN107349919 B. The preparation method includes: a) mixing fibers, a polymer, a double-bond monomer, and water, and subjecting the mixture to electron beam irradiation to produce a gel; the polymer comprises one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polystyrene, and polyacrylonitrile; and the double-bond monomer comprises one or more of acrylonitrile, divinylbenzene, styrene, acrylic acid, acrylamide, butadiene, pentadiene, and triallyl isocyanurate; b) mixing the gel with acrylonitrile and subjecting the mixture to electron beam irradiation to produce a grafted cross-linked product; and c) mixing the grafted cross-linked product with hydroxylamine and reacting the product to produce the uranyl adsorbent material. This adsorbent has a very low adsorption capacity. Summary of the Invention

[0004] The present invention provides an adsorbent, a preparation method and application thereof, which solve the problem that the adsorption capacity of uranyl adsorption materials prepared in the prior art is too low.

[0005] An adsorbent having the following structural formula:

[0006]

[0007] The second object of the present invention is to protect a method for preparing the adsorbent, which specifically comprises the following steps:

[0008] After dissolving phloroglucinol, 2,6-dichloropyridine-3,5-dicarbonitrile and a basic catalyst, the reaction is carried out for 1 h to 1.5 h. The organic layer after extraction is vacuum dried at 60°C to 80°C for 12 h to 48 h to obtain a molecular cage containing a cyano group;

[0009] Under alkaline conditions, the obtained molecular cage containing a cyano group and hydroxylamine hydrochloride are dissolved, reacted at 58° C. to 65° C. for 24 to 48 hours, and the obtained solid is filtered and vacuum dried at 100° C. to 110° C. for 12 to 48 hours to obtain the adsorbent.

[0010] The molecular cage synthesized by reacting 2,6-dichloropyridine-3,5-dicarbonitrile with phloroglucinol under an alkaline catalyst contains numerous cyano groups, which can be converted into amidoxime groups with specific adsorption properties for uranium ions. The adsorbent prepared in this invention contains six amidoxime molecular cages as structural units within a single molecule.

[0011] The reaction temperature of 58°C to 65°C is selected because when the temperature is too high, the cyano group is easily converted into a carboxyl group, and the boiling point of the solvent is 65°C. Therefore, in order to improve the yield and ensure that the reaction can be completely converted into an amidoxime group, the temperature is set to this range.

[0012] Preferably, when preparing the adsorbent, the molar ratio of the molecular cage containing a cyano group to hydroxylamine hydrochloride is 1:12-24.

[0013] Preferably, the molar ratio of phloroglucinol, 2,6-dichloropyridine-3,5-dicarbonitrile and the alkaline catalyst is 2:3:4-8.

[0014] The molar ratio of the molecular cage containing a cyano group and hydroxylamine hydrochloride, and the molar ratio of phloroglucinol and 2,6-dichloropyridine-3,5-dicarbonitrile were all set according to the number of reactive groups.

[0015] Preferably, the alkaline catalyst is any one of cesium carbonate, potassium carbonate, sodium carbonate, sodium hydroxide, and potassium hydroxide.

[0016] Preferably, the structural formula of the molecular cage containing a cyano group is as follows:

[0017]

[0018] Preferably, the adsorbent is crystallized at -5°C to 35°C to obtain a porous organic hydrogen bond material.

[0019] Preferably, when the adsorbent is crystallized at -5°C to 24°C, the prepared porous organic hydrogen-bonded material has an R-3C space group, and the unit cell parameters are: α=90°, β=90°, γ=120°.

[0020] Preferably, when the adsorbent is crystallized at 25°C to 35°C, the prepared porous organic hydrogen-bonded material has a P-1 space group, and the unit cell parameters are: α=98.1°, β=106.6°, γ=94.3°.

[0021] The third object of the present invention is to protect the adsorbent as the porous organic hydrogen bond material, and the porous organic hydrogen bond material is used for extracting uranium from seawater.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The main structure of the adsorbent obtained by the present invention is a molecular cage containing an amidoxime group. Compared with other groups, the amidoxime functional group shows great potential as a uranium absorbent due to its selectivity and high chelating affinity for uranium. At the same time, the organic structural unit contains many electronegative nitrogen and oxygen atoms, which can play a synergistic role in the selective adsorption of uranium ions. The adsorbent obtained by the present invention is crystallized to obtain a porous organic hydrogen-bonded material, and the uranium ion adsorption rate can reach a maximum of 1727 mg·g at room temperature. -1 The porous organic hydrogen-bonded material obtained by the present invention has high crystallinity. Unlike other different types of amidoxime-based adsorbents, such as nanofibers, resins, hydrogels, covalent organic frameworks, and porous aromatic frameworks, the porous organic hydrogen-bonded material has orderly pores and a clear structure. It also contains a large number of available chelating active sites, which can allow uranium ions to enter the pores and be selectively adsorbed between layers, meeting the requirements for practical applications in seawater.

[0024] In addition, the porous organic hydrogen bond material obtained by the present invention has good U / V selectivity and can maintain its structural stability even after 7 adsorption-desorption cycles, with an adsorption rate of more than 90%. In natural seawater, the porous organic hydrogen bond material has reached 10.85 mg·g after 30 days of field testing. -1 Considering these advantages, the present invention has great potential for uranium immobilization and opens up a new concept for the synthesis of uranium recovery materials.

[0025] 2. The adsorbent prepared by the present invention produces porous organic hydrogen-bonding materials with different crystal forms after crystallization at different temperatures. Crystal structures formed at 25°C to 35°C exhibit high adsorption capacity, while those formed at -5°C to 24°C exhibit low adsorption capacity. This is because the material formed at high temperatures has internal pores through which uranium ions can pass, while those formed at low temperatures lack these pores, resulting in adsorption only on the surface of the adsorbent.

[0026] 3. The preparation method of the porous organic hydrogen bond material for extracting uranium from seawater of the present invention is simple, the raw materials are cheap, the instruments used are conventional, and it is easy to use. It has good application prospects in the field of uranium extraction from seawater and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1This is the infrared spectrum of the cyano-containing molecular cage and its amide oximation obtained in Example 1 of the present invention;

[0028] Figure 2 This is the H NMR spectrum of the amidoxime molecular cage obtained in Example 1 of the present invention;

[0029] Figure 3 This is the C NMR spectrum of the amidoxime molecular cage obtained in Example 1 of the present invention;

[0030] Figure 4 This is the X-ray single crystal diffraction pattern of the porous organic hydrogen-bonding material prepared in Example 1;

[0031] Figure 5 This is the X-ray single crystal diffraction pattern of the porous organic hydrogen-bonding material prepared in Example 2;

[0032] Figure 6 This is a graph showing the isothermal adsorption performance of the porous organic hydrogen-bonding material obtained in Example 1 of the present invention for adsorbing uranium ions;

[0033] Figure 7 This is a kinetic diagram of the adsorption of uranium ions by the porous organic hydrogen-bonding material obtained in Example 1 of the present invention;

[0034] Figure 8 Graph showing the effect of pH on the adsorption of uranyl ions by the porous organic hydrogen-bonding material obtained in Example 1 of the present invention;

[0035] Figure 9 This is a graph showing the uranyl ion adsorption selectivity test of the porous organic hydrogen-bonding material obtained in Example 1 of the present invention;

[0036] Figure 10 This is a graph showing the uranium cyclic adsorption and desorption test of the porous organic hydrogen-bonding material obtained in Example 1 of the present invention;

[0037] Figure 11 This is a test chart of the porous organic hydrogen bond material obtained in Example 1 of the present invention adsorbing uranyl ions in natural seawater. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the specific implementation of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Unless otherwise specified, the methods described in the embodiments of the present invention are conventional methods. The materials and reagents used are all commercially available unless otherwise specified.

[0040] The structure of the molecular cage containing a cyano group prepared in the embodiment of the present invention is as follows:

[0041]

[0042] Example 1

[0043] A method for preparing an adsorbent comprises the following steps:

[0044] (1) Under ambient atmosphere, 1.59 mmol of phloroglucinol, i.e., 200 mg, 2.38 mmol of 2,6-dichloropyridine-3,5-dicarbonitrile, i.e., 472 mg, and 4 mmol of cesium carbonate, i.e., 1.30 g, were added to a round-bottom flask, and 50 mL of anhydrous dimethyl sulfoxide was added. The mixture was stirred for 1 hour to obtain a mixed product. The mixed product was extracted with 100 mL of ethyl acetate and 100 mL of ultrapure water, separated, and the aqueous layer was extracted twice with 40 mL of ethyl acetate. The organic layers were combined. The combined organic layers were washed with 100 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the liquid was evaporated to remove the solvent to obtain a mixed solid. The obtained mixed solid was then washed three times with anhydrous methanol, filtered, and the washed solid was vacuum dried at 60°C for 12 hours. The obtained solid was a molecular cage containing a cyano group.

[0045] (2) Under ambient atmosphere, 251 mg of the cyano group-containing molecular cage prepared in step (1), 333.3 mg of hydroxylamine hydrochloride and 192 mg of sodium hydroxide were placed in a round-bottom flask, 30 mL of methanol was added, and the reaction was carried out at 58° C. for 24 h. After that, the product was filtered, washed with ultrapure water, and the solid was vacuum-dried at 110° C. for 12 h to obtain an amide oxime molecular cage, i.e., the adsorbent.

[0046] (3) Dissolve 50 mg of the adsorbent prepared in step (2) in 70 mL of methanol at 25° C. and evaporate at room temperature for 2 days to obtain a porous organic hydrogen bond material.

[0047] The porous organic hydrogen-bonding material prepared in this embodiment has a P-1 space group, and the unit cell parameters are: α=98.1°, β=106.6°, γ=94.3°.

[0048] Example 2

[0049] A method for preparing an adsorbent comprises the following steps:

[0050] (1) Under ambient atmosphere, 1.59 mmol of phloroglucinol, i.e., 200 mg, 2.38 mmol of 2,6-dichloropyridine-3,5-dicarbonitrile, i.e., 472 mg, and 4 mmol of cesium carbonate, i.e., 1.30 g, were added to a round-bottom flask, and 50 mL of anhydrous dimethyl sulfoxide was added. The mixture was stirred for 1 hour to obtain a mixed product. The mixed product was extracted with 100 mL of ethyl acetate and 100 mL of ultrapure water, separated, and the aqueous layer was extracted twice with 40 mL of ethyl acetate. The organic layers were combined. The combined organic layers were washed with 100 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the liquid was evaporated to remove the solvent to obtain a mixed solid. The obtained mixed solid was then washed three times with anhydrous methanol, filtered, and the washed solid was vacuum dried at 60°C for 12 hours. The obtained solid was a molecular cage containing a cyano group.

[0051] (4) Under ambient atmosphere, 251 mg of the cyano group-containing molecular cage prepared in step (1), 333.3 mg of hydroxylamine hydrochloride, and 192 mg of sodium hydroxide were placed in a round-bottom flask, 30 mL of methanol was added, and the mixture was reacted at 58° C. for 24 h. After that, the product was filtered, washed with ultrapure water, and the solid was vacuum-dried at 110° C. for 12 h to obtain an amide oxime molecular cage, i.e., the adsorbent.

[0052] (5) Dissolve 50 mg of the adsorbent prepared in step (2) in 70 mL of methanol at 29° C. and evaporate at room temperature for 2 days to obtain a porous organic hydrogen bond material.

[0053] The porous organic hydrogen-bonding material prepared in this embodiment has a P-1 space group, and the unit cell parameters are: α=98.1°, β=106.6°, γ=94.3°.

[0054] Example 3

[0055] A method for preparing an adsorbent comprises the following steps:

[0056] (1) Under ambient atmosphere, 1.59 mmol of phloroglucinol, i.e., 200 mg, 2.38 mmol of 2,6-dichloropyridine-3,5-dicarbonitrile, i.e., 472 mg, and 4 mmol of cesium carbonate, i.e., 1.30 g, were added to a round-bottom flask, and 50 mL of anhydrous dimethyl sulfoxide was added. The mixture was stirred for 1 hour to obtain a mixed product. The mixed product was extracted with 100 mL of ethyl acetate and 100 mL of ultrapure water, separated, and the aqueous layer was extracted twice with 40 mL of ethyl acetate. The organic layers were combined. The combined organic layers were washed with 100 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the liquid was evaporated to remove the solvent to obtain a mixed solid. The obtained mixed solid was then washed three times with anhydrous methanol, filtered, and the washed solid was vacuum dried at 60°C for 12 hours. The obtained solid was a molecular cage containing a cyano group.

[0057] (6) Under ambient atmosphere, 251 mg of the cyano group-containing molecular cage prepared in step (1), 333.3 mg of hydroxylamine hydrochloride, and 192 mg of sodium hydroxide were placed in a round-bottom flask, 30 mL of methanol was added, and the reaction was carried out at 58° C. for 24 h. After that, the product was filtered, washed with ultrapure water, and the solid was vacuum-dried at 110° C. for 12 h to obtain an amide oxime molecular cage, i.e., the adsorbent.

[0058] (7) Dissolve 50 mg of the adsorbent prepared in step (2) in 70 mL of methanol at 35° C. and evaporate at room temperature for 2 days to obtain a porous organic hydrogen bond material.

[0059] The porous organic hydrogen-bonding material prepared in this embodiment has a P-1 space group, and the unit cell parameters are: α=98.1°, β=106.6°, γ=94.3°.

[0060] Example 4

[0061] A method for preparing an adsorbent comprises the following steps:

[0062] (1) Under ambient atmosphere, 1.59 mmol of phloroglucinol, i.e., 200 mg, 2.38 mmol of 2,6-dichloropyridine-3,5-dicarbonitrile, i.e., 472 mg, and 4 mmol of cesium carbonate, i.e., 1.30 g, were added to a round-bottom flask, and 50 mL of anhydrous DMSO was added. The mixture was stirred for 1 h to obtain a mixed product. The mixed product was extracted with 100 mL of ethyl acetate and 100 mL of ultrapure water, separated, and the aqueous layer was extracted twice with 40 mL of ethyl acetate. The organic layers were combined. The combined organic layers were washed with 100 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the liquid was evaporated to remove the solvent to obtain a mixed solid. The obtained mixed solid was then washed three times with anhydrous methanol, filtered, and the washed solid was vacuum dried at 60°C for 12 h. The obtained solid was a molecular cage containing a cyano group.

[0063] (2) Under ambient atmosphere, 251 mg of the cyano group-containing molecular cage prepared in step (1), 500 mg of hydroxylamine hydrochloride, and 288 mg of sodium hydroxide were placed in a round-bottom flask, 30 mL of methanol was added, and the mixture was reacted at 58° C. for 24 h. After that, the product was filtered, washed with ultrapure water, and the solid was vacuum-dried at 110° C. for 12 h to obtain an amide oxime molecular cage, i.e., the adsorbent.

[0064] (3) Dissolve 50 mg of the adsorbent prepared in step (2) in 70 mL of methanol at 5° C. and slowly evaporate for 2 days under ambient atmosphere to obtain a porous organic hydrogen bond material.

[0065] The porous organic hydrogen-bonding material prepared in this embodiment has an R-3C space group, and the unit cell parameters are: α=90°, β=90°, γ=120°.

[0066] Example 5

[0067] A method for preparing an adsorbent comprises the following steps:

[0068] (1) Under ambient atmosphere, 1.59 mmol of phloroglucinol, i.e., 200 mg, 2.38 mmol of 2,6-dichloropyridine-3,5-dicarbonitrile, i.e., 472 mg, and 7 mmol of cesium carbonate, i.e., 2.28 g, were added to a round-bottom flask, and 50 mL of anhydrous DMSO was added. The mixture was stirred for 1 h to obtain a mixed product. The mixed product was extracted with 100 mL of ethyl acetate and 100 mL of ultrapure water, separated, and the aqueous layer was extracted twice with 40 mL of ethyl acetate. The organic layers were combined. The combined organic layers were washed with 100 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the liquid was evaporated to remove the solvent to obtain a mixed solid. The obtained mixed solid was then washed three times with anhydrous methanol, filtered, and the washed solid was vacuum dried at 70°C for 36 h. The obtained solid was a molecular cage containing a cyano group.

[0069] (2) Under ambient atmosphere, 251 mg of the cyano group-containing molecular cage prepared in step (1), 583.3 mg of hydroxylamine hydrochloride and 336 mg of sodium hydroxide were placed in a round-bottom flask, 30 mL of methanol was added, and the reaction was carried out at 63° C. for 40 h. After that, the product was filtered, washed with ultrapure water, and the solid was vacuum-dried at 110° C. for 36 h to obtain an amide oxime molecular cage, i.e., the adsorbent.

[0070] (3) Dissolve 50 mg of the adsorbent prepared in step (2) in 70 mL of methanol at -5°C and slowly evaporate for 2 days under ambient atmosphere to obtain a porous organic hydrogen bond material.

[0071] The porous organic hydrogen-bonding material prepared in this embodiment has an R-3C space group, and the unit cell parameters are: α=90°, β=90°, γ=120°.

[0072] Example 6

[0073] A method for preparing an adsorbent comprises the following steps:

[0074] (1) Under ambient atmosphere, 1.59 mmol of phloroglucinol, i.e., 200 mg, 2.38 mmol of 2,6-dichloropyridine-3,5-dicarbonitrile, i.e., 472 mg, and 8 mmol of cesium carbonate, i.e., 2.61 g, were added to a round-bottom flask, and 50 mL of anhydrous DMSO was added. The mixture was stirred for 1 h to obtain a mixed product. The mixed product was extracted with 100 mL of ethyl acetate and 100 mL of ultrapure water, separated, and the aqueous layer was extracted twice with 40 mL of ethyl acetate. The organic layers were combined. The combined organic layers were washed with 100 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the liquid was evaporated to remove the solvent to obtain a mixed solid. The obtained mixed solid was then washed three times with anhydrous methanol, filtered, and the washed solid was vacuum dried at 80°C for 48 h. The obtained solid was a molecular cage containing a cyano group.

[0075] (2) Under ambient atmosphere, 251 mg of the cyano group-containing molecular cage prepared in step (1), 666.7 mg of hydroxylamine hydrochloride and 384 mg of sodium hydroxide were placed in a round-bottom flask, 30 mL of methanol was added, and the mixture was reacted at 65° C. for 48 h. After that, the product was filtered, washed with ultrapure water, and the solid was vacuum dried at 110° C. for 48 h to obtain an amide oxime molecular cage, i.e., the adsorbent.

[0076] (3) Dissolve 50 mg of the adsorbent prepared in step (2) in 70 mL of methanol at 10° C. and slowly evaporate for 2 days under ambient atmosphere to obtain a porous organic hydrogen bond material.

[0077] The porous organic hydrogen-bonding material prepared in this embodiment has an R-3C space group, and the unit cell parameters are: α=90°, β=90°, γ=120°.

[0078] Comparative Example 1

[0079] Refer to Example 3 of Chinese patent CN 107349919 B.

[0080] A method for synthesizing uranyl adsorption material:

[0081] (1) 11 parts by weight of straw fiber (fineness ≥30 mesh, ash content ≤2wt%) are put into a mixing tank, and 600 parts by weight of clean water, 130 parts by weight of polyvinyl alcohol (brand 1799), 20 parts by weight of styrene, 0.9 parts by weight of acrylonitrile, 0.5 parts by weight of fatty alcohol polyoxyethylene ether (brand AEO-3), and 12 parts by weight of isopropyl alcohol are added and stirred evenly; the brand of polyvinyl alcohol is 1799, and the brand of fatty alcohol polyoxyethylene ether is AEO-3.

[0082] (2) The prepared solution in (1) is irradiated under an electron beam until the absorbed dose of the solution reaches 100 kGy, thereby obtaining a gel sheet.

[0083] (3) The gel sheet obtained in (2) is cut into gel particles by a cutting machine.

[0084] (4) 10 parts by weight of the particles obtained in (3) were added to 1.8 parts by weight of acrylonitrile, mixed evenly, and irradiated under an electron beam at a dose of 60 kGy to obtain a graft cross-linked body.

[0085] (5) 4.8 parts by weight of hydroxylamine hydrochloride was added to the graft cross-linked product of (4), and the temperature was controlled to react at 80° C. for 6 hours to obtain a uranyl adsorption material.

[0086] In this embodiment, the particle size of the uranyl adsorption material finally obtained is controlled to be 30-80 meshes by controlling the size of the colloid particles in step (3).

[0087] Performance Testing

[0088] 1) The apparent density of the prepared adsorption material was tested and the result was: 0.6g / cm 3 .

[0089] 2) A solution containing 0.9 mg / L uranium ions was prepared, and the prepared adsorption material was used for adsorption at room temperature under static conditions for 2 weeks. After elution, the adsorption amount was measured to be 4.7 mg / g.

[0090] 3) A 10 mg / L solution containing uranium ions was prepared and the prepared adsorption material was used for adsorption at room temperature under static conditions for one day. After elution, the adsorption capacity was measured to be 29 mg / g; the adsorption capacity of the above-mentioned adsorption material after the third elution was 85.3% of the original adsorption capacity.

[0091] The maximum adsorption capacity of the porous organic hydrogen bond materials prepared in Examples 2 and 3 is 1723±10 mg·g -1 Therefore, the following performance test only takes the porous organic hydrogen bond material prepared in Example 1 as an example. Since the maximum adsorption capacity of the porous organic hydrogen bond materials prepared in Examples 4, 5, and 6 is relatively low, all at 300 mg·g -1 Therefore, the subsequent equilibrium adsorption amount is only based on the porous organic hydrogen bond material prepared in Example 4 as an example.

[0092] The maximum adsorption capacity of uranium ions by the uranyl adsorption material in Comparative Example 1 is 29 mg·g -1 The porous organic hydrogen bond material prepared in Example 1 of the present invention has a higher adsorption capacity of 1723 mg g -1Even after seven adsorption-desorption cycles, the material maintained structural stability, achieving an adsorption rate exceeding 90%, demonstrating cyclic adsorption performance superior to that of the uranyl adsorbent material prepared in Comparative Example 1. Furthermore, the adsorption capacity of the adsorbent of Example 1 in natural seawater was also higher than that of the ionically cross-linked supramolecular hydrogel membrane prepared in Comparative Example 1. This demonstrates the enormous potential of the present invention for uranium immobilization, meeting practical requirements for seawater applications and opening up a new concept for the synthesis of uranium recovery materials.

[0093] Figure 1 The infrared spectrum of the molecular cage containing cyano group and its amide oximation obtained in Example 1 of the present invention is shown in Figure 1. The infrared spectrum of the molecular cage before and after amide oximation is tested. Figure 1 As shown in the figure, the peak of the typical bond representing the cyanide C≡N stretching vibration in the cyanide molecular cage is at 2238cm -1 The amide oxime molecular cage showed no distinct signal. However, the amide oxime molecular cage showed a C=N-related characteristic signal region within its infrared peak. In summary, the cyano groups were completely converted to amide oxime groups, indicating successful amide oximation of the molecular cage.

[0094] Figure 2 This is the nuclear magnetic hydrogen spectrum of the amidoxime molecular cage obtained in Example 1 of the present invention. 1 H nuclear magnetic test, the test results are as follows Figure 2 As shown in the figure, two singlets correspond to the amidoxime groups, with the chemical shift peak at 9.60 ppm attributed to the hydroxyl group and the singlet at 5.82 ppm attributed to the amino group, indicating that the molecular cage has been successfully amidoximated. In addition, we also observed two aromatic proton peaks with chemical shifts of 7.96 and 6.79 ppm, both of which are singlets.

[0095] Figure 3 This is the NMR carbon spectrum of the amidoxime molecular cage obtained in Example 1 of the present invention. 13 C nuclear magnetic test, the test results are as follows Figure 3 As shown in the figure, there are six chemical shift peaks, corresponding to six carbon atoms in different environments in the amide oxime molecular cage.

[0096] Figure 4 This is the X-ray single crystal diffraction pattern of the porous organic hydrogen-bonding material prepared in Example 1. The displacement ellipsoid is scaled to a 50% probability level. Figure 5This is the X-ray single crystal diffraction pattern of the porous organic hydrogen bond material prepared in Example 4. The displacement ellipsoid is scaled to a probability level of 50%. The crystallization temperatures of Example 1 and Example 4 are different, and the crystal arrangements of the porous organic hydrogen bond material obtained are different. The adsorbent has a large adsorption capacity for the crystal structure formed at 25°C to 35°C, and a small adsorption capacity for the crystal structure formed at -5°C to 24°C. This is because the material formed at high temperature has pores inside that allow uranium ions to pass through, while the material formed at low temperature has no pores and can only be adsorbed on the surface of the adsorbent.

[0097] Figure 6 The isothermal adsorption performance curves of the porous organic hydrogen-bonding material obtained in Example 1 of the present invention for uranium ions are shown as HPOC-α; and the isothermal adsorption performance curves of the porous organic hydrogen-bonding material obtained in Example 4 for uranium ions are shown as HPOC-β. Simulated uranium solutions with different initial concentrations, i.e., 1.0 to 80.0 mg·L, were prepared at a pH of 7.0. -1 , used for equilibrium adsorption isotherm experiments. 1 mg of the adsorbent prepared in Example 1 was added to 80 mL of uranium solution to obtain a uranium solution after adsorption. After stirring at room temperature for 24 hours, the adsorbed uranium solution was removed and analyzed according to the arsenazo III test. The equilibrium isotherm data were fitted using the Langmuir and Freundlich adsorption isotherms, respectively, using the following equations:

[0098]

[0099] Among them, C in formula (1) and formula (2) e is the equilibrium concentration, in mg·g -1 ;q m Indicates saturated adsorption capacity, unit: mg·g -1 ;q e Indicates the equilibrium adsorption capacity, unit: mg·g -1 ; k1 represents the Langmuir constant, which is related to the affinity of the binding site. It can be seen from the figure that Example 1 belongs to Langmuir monolayer chemical adsorption, and the maximum adsorption capacity is 1727 mg·g -1 The porous organic hydrogen-bonding material prepared in Example 4 has a relatively small adsorption capacity for uranium ions. The following tests were conducted using the porous organic hydrogen-bonding material prepared in Example 1.

[0100] Figure 7The kinetic diagram of the adsorption of uranium ions by the porous organic hydrogen-bonding material obtained in Example 1 of the present invention. Under the condition of pH 7.0, the uranium capture kinetics experiment was measured at concentrations of 10ppm, 20ppm and 30ppm. 3.0mg of the porous organic hydrogen-bonding material obtained in Example 1 was soaked and dispersed into 300mL of uranium simulated seawater, and then 0.5mL of the solution was taken out at 1h, 3h, 6h, 9h, 12h, 24h, 36h, 48h, 60h, 72h, 84h, 96h and 120h of reaction, and centrifuged for detection. In order to further study the adsorption kinetics mechanism, we listed the pseudo-first-order model and the pseudo-second-order model as the following equations:

[0101]

[0102] ln(qE-qt)=lnqE-kt 式(4)

[0103] Wherein, qe in formula (3) and formula (4) represents the equilibrium adsorption capacity, with the unit of mg·g- 1 ; k1 represents the rate constant, unit is g·h- 1 mg- 1 ; qt is the amount of uranium adsorbed after contact time t, in mg g- 1 ; Ct is the uranium concentration at time t, in mg·g- 1 k3 is the kinetic rate constant, and t is the reaction time in hours. When adsorption equilibrium is reached, qt and Ct are replaced by qe and Ce, respectively.

[0104] from Figure 7 It can be seen from the figure that the porous organic hydrogen bond material obtained in Example 1 reaches equilibrium with uranium simulation solutions of different concentrations in about 24 hours.

[0105] Figure 8 Figure 1 is the effect of pH on the adsorption of uranyl ions by the porous organic hydrogen-bonding material obtained in Example 1 of the present invention. To obtain the optimal pH for uranium ion adsorption by the porous organic hydrogen-bonding material in Example 1, 1 mg of the porous organic hydrogen-bonding material sample was added to 80 mL of a 10 mg·L- 1 The uranium simulation solution contains 438.607×10- 3 M sodium chloride and 2.297×10- 3 The solution was divided into seven portions and the pH was adjusted with hydrochloric acid and sodium hydroxide to 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0, respectively. After shaking with a magnetic stirrer at room temperature for 36 hours, the samples were separated and analyzed for residual uranium concentration using inductively coupled plasma optical emission spectroscopy (ICP-OES). The adsorption capacity was expressed as qt and calculated using the following formula:

[0106]

[0107] Wherein, qt in formula (5) is the amount of uranium adsorbed after contact time t, and the unit is mg·g- 1 ; C0 is the initial uranium concentration, unit is mg·g- 1 ; Ct is the uranium concentration at time t, in mg·g- 1 ; V is the volume of the solution, in L; m is the mass of the adsorbent used, in g.

[0108] from Figure 8 It can be seen that the porous organic hydrogen bond material obtained in Example 1 has the largest adsorption capacity when the pH is 7, which is close to the pH of real seawater ≈ 8, so the porous organic hydrogen bond material obtained in Example 1 can be used for uranium extraction from seawater.

[0109] Figure 9 This is a test diagram of the uranyl ion adsorption selectivity of the porous organic hydrogen-bonding material obtained in Example 1 of the present invention. In order to accurately determine the affinity of the porous organic hydrogen-bonding material obtained in Example 1 for uranyl ions, the metal ion Fe 3+ , VO 2+ , Ni 2 + , Zn 2+ , Sr 2+ , Pb 2+ ,Co 2+ ,Ba 2+ , Cu 2+ , Cd 2+ With uranyl ion, UO2 2+ Mixed with natural seawater concentrated 100 times to obtain a mixture; + Mg 2+ , Ca 2+ , K + The concentrations of the porous organic hydrogen-bonding material remained at their original concentrations, i.e., sodium ions: 10.716 g / L, magnesium ions: 1.287 g / L, calcium ions: 0.41 g / L, and potassium ions: 0.397 g / L. The pH value of the mixture was adjusted to 6.0, and then 5.0 mg of the porous organic hydrogen-bonding material was immersed in 400 mL of the mixture and shaken for 72 hours. The uranium concentration remaining in the solution was then recorded and analyzed using inductively coupled plasma mass spectrometry, abbreviated as ICP-MS. It can be analyzed that the porous organic hydrogen-bonding material obtained in Example 1 exhibited a U / V selectivity of 1.51 times, providing potential applications for uranium recovery in natural seawater.

[0110] Figure 10This is a graph showing the uranium cyclic adsorption and desorption test of the porous organic hydrogen-bonding material obtained in Example 1 of the present invention. In order to evaluate the reusability of the porous organic hydrogen-bonding material obtained in Example 1, 5.0 mg of the porous organic hydrogen-bonding material obtained in Example 1 was immersed in 400 mL of a 20.0 mg·L -1 The uranium was added to the simulated seawater and stirred continuously for 24 hours. The porous organic hydrogen bond material that adsorbed uranium ions was then separated and regenerated with 200 mL of a mixed eluent of 1 M sodium carbonate and 0.1 M hydrogen peroxide until the concentration of the elution solution could not be detected by ICP-MS; the molar ratio of sodium carbonate and 0.1 M hydrogen peroxide was 10:1. During the desorption process, we need to immerse the separated and regenerated porous organic hydrogen bond material in 500 mL of deionized water and wash it twice with circulating ultrapure water to completely remove the eluent. As mentioned above, the uranium adsorption-desorption cycle experiment was repeated 7 times. From Figure 9 It can be seen from the figure that after 7 cycles, the adsorption rate is still above 90%, indicating that the porous organic hydrogen bond material obtained in Example 1 has excellent stability.

[0111] Figure 11 This is a test diagram of the porous organic hydrogen bond material obtained in Example 1 of the present invention adsorbing uranyl ions in natural seawater. In order to detect the uranium absorption capacity of the porous organic hydrogen bond material obtained in Example 1 in natural seawater, a flow test platform for laboratory field testing was established. Natural seawater collected from the Bohai Sea area near the coast of Qingdao City, Shandong Province, was filtered through a 0.22μm filter membrane to remove marine microorganisms and suspended matter. 10.0mg of the porous organic hydrogen bond material obtained in Example 1 was placed in the above-mentioned equipment, 50L of filtered natural seawater was added, and the mixture was stirred at room temperature at a rate of 1L·min -1 Three parallel experiments were conducted simultaneously at a flow rate of 100 nm. The concentrations of uranium-based and other metal ions in seawater were analyzed at regular intervals using ICP-MS. The porous organic hydrogen-bonding material prepared by the present invention exhibited an extremely fast adsorption rate within the first 10 days and reached 10.85 mg·g after 30 days of testing. -1 It has strong uranium absorption capacity and extremely strong adsorption properties.

[0112] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0113] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An adsorbent, characterized in that The structural formula of the adsorbent is as follows:

2. The method for preparing an adsorbent according to claim 1, wherein: The specific steps include: After dissolving phloroglucinol, 2,6-dichloropyridine-3,5-dicarbonitrile and a basic catalyst, the reaction is carried out for 1 h to 1.5 h, and the organic layer after extraction is a molecular cage containing a cyano group; The structural formula of the molecular cage containing a cyano group is as follows: Under alkaline conditions, the obtained molecular cage containing a cyano group and hydroxylamine hydrochloride are dissolved, reacted at 58° C. to 65° C. for 24 to 48 hours, and then the solid obtained by filtering is used as the adsorbent.

3. The method for preparing an adsorbent according to claim 2, characterized in that: When preparing the adsorbent, the molar ratio of the molecular cage containing the cyano group to the hydroxylamine hydrochloride is 1:12-24.

4. The method for preparing an adsorbent according to claim 3, characterized in that: The molar ratio of the phloroglucinol, 2,6-dichloropyridine-3,5-dicarbonitrile and the alkaline catalyst is 2:3:4-8.

5. The method for preparing an adsorbent according to claim 4, characterized in that: The alkaline catalyst is any one of cesium carbonate, potassium carbonate, sodium carbonate, sodium hydroxide and potassium hydroxide.

6. The method for preparing an adsorbent according to claim 2, characterized in that: The adsorbent is crystallized at -5°C to 35°C to obtain a porous organic hydrogen bond material.

7. The method for preparing an adsorbent according to claim 6, characterized in that: When the adsorbent is crystallized at -5°C to 24°C, the prepared porous organic hydrogen-bonded material has an R-3C space group, and the unit cell parameters are: α=90°, β=90°, γ=120°.

8. The method for preparing an adsorbent according to claim 7, characterized in that: When the adsorbent is crystallized at 25°C to 35°C, the prepared porous organic hydrogen-bonded material has a P-1 space group, and the unit cell parameters are: α=98.1°, β=106.6°, γ=94.3°.

9. An application of an adsorbent, characterized in that: The adsorbent is the porous organic hydrogen bond material according to claim 7, and the porous organic hydrogen bond material is used for extracting uranium from seawater.

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