A carboxylated aromatic oxime adsorbent and its preparation method and application

Abstract

The present invention provides a carboxylated aromatic oxime adsorbent and a preparation method and application thereof, belonging to the technical field of uranium adsorption materials. The carboxylated aromatic oxime adsorbent provided by the present invention has a structural formula as described. The present invention introduces hydrophilic carboxyl groups and selective amidoximes into the main chain of polymer molecules. On the one hand, the hydrophilic carboxyl groups are beneficial to the rapid diffusion of uranyl ions at the phase interface, greatly improving the uranium adsorption kinetics. On the other hand, they can synergistically enrich uranium elements with amidoximes, so that the target adsorbent has a larger adsorption capacity and a faster adsorption rate.

Description

Technical Field

[0001] The invention relates to the technical field of uranium adsorption materials, and in particular to a carboxylated aromatic oxime adsorbent and a preparation method and application thereof. Background Art

[0002] As a clean energy, nuclear energy has become one of the biggest contributors to low carbon emissions. However, uranium resources are in short supply, and the proven reserves of uranium mines cannot meet the long-term needs of nuclear power development. Therefore, it is urgent to find new uranium resources.

[0003] The ocean contains about 4.5 billion tons of uranium, and the extremely low uranium concentration (3.3 ppb, one part per billion) and the presence of a large number of coexisting ions make it extremely difficult to recover uranium from seawater. Therefore, it is necessary to develop an efficient uranium recovery strategy. Adsorption is the most effective and commonly used method for enriching uranium. Polyacrylonitrile amidoxime (PAO) has become a mainstream uranium adsorbent due to its specific complexation with uranium. However, PAO adsorbents have the disadvantages of poor hydrophilicity and a single adsorption site, resulting in slow adsorption kinetics and small adsorption capacity. In addition, the mechanical properties of PAO membranes are poor and they do not have the ability to support. The application of PAO often requires the introduction of supporting resins, which inevitably reduces the uranium adsorption capacity. Therefore, it is urgent to develop an adsorbent with a fast adsorption rate, high adsorption capacity and self-supporting characteristics. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a carboxylated aromatic oxime adsorbent and a preparation method and application thereof. The adsorbent provided by the present invention has faster adsorption kinetics and higher adsorption capacity for uranium in seawater.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a carboxylated aromatic oxime compound having a structure shown in Formula I:

[0006]

[0007] The mass average molecular weight Mw of the carboxylated aromatic oxime compound is 70,000 to 250,000.

[0008] Preferably, the structural formula of the carboxylated aromatic oxime compound is:

[0009]

[0010] The present invention also provides a method for preparing the carboxylated aromatic oxime compound, comprising the following steps:

[0011] Under an inert atmosphere, carboxylated bisphenol and difluorocyanide undergo salt formation and polycondensation reactions in sequence to obtain an adsorbent intermediate;

[0012] The adsorbent intermediate is oximated in a hydroxylamine solution to obtain the carboxylated aromatic oxime.

[0013] Preferably, the carboxylated bisphenol is:

[0014]

[0015] The difluorocyanate is:

[0016]

[0017] Preferably, the molar ratio of the cyanide bisfluoride to the carboxylated bisphenol is 1:1 to 1:1.1.

[0018] Preferably, the temperature of the salt formation is 120-135° C., and the time is 2-3 h; the temperature of the polycondensation is 155-160° C., and the time is 5-6 h.

[0019] Preferably, the amount of hydroxylamine used is 2.5 to 10 times the molar equivalent of the difluorocyanate.

[0020] Preferably, the oximation temperature is 60° C. and the time is 48 h.

[0021] The invention also provides a self-supporting porous uranium element adsorbent. The self-supporting porous uranium element adsorbent is prepared by subjecting the carboxylated aromatic oxime compound to a non-solvent induced phase separation method.

[0022] The present invention also provides the use of the carboxylated aromatic oxime compound or the self-supporting porous uranium adsorbent described in the above technical solution for extracting uranium from seawater.

[0023] Beneficial technical effects:

[0024] The present invention introduces hydrophilic carboxyl groups and selective amidoximes into the main chain of polymer molecules. The hydrophilic carboxyl groups are beneficial to the rapid diffusion of uranyl ions at the phase interface, greatly improving the uranium adsorption kinetics, and can synergistically enrich uranium elements with amidoximes.

[0025] The self-supporting porous uranium element adsorbent provided by the present invention is applied to extract uranium from seawater and exhibits a faster adsorption rate and a higher adsorption capacity, and has self-supporting performance and excellent mechanical properties, without the need to introduce additional supporting resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1This is the high temperature gel chromatography test chart of carboxylated aromatic oxime in Example 1;

[0028] Figure 2 FTIR spectra of the target adsorbent (i.e., carboxylated aromatic oxime) and the adsorbent intermediate in Example 1;

[0029] Figure 3 is the adsorbent intermediate in Example 1 1 H NMR spectrum;

[0030] Figure 4 is the carboxylated aromatic oxime in Example 1 1 H NMR spectrum;

[0031] Figure 5 This is the high temperature gel chromatography test chart of carboxylated aromatic oxime in Example 2;

[0032] Figure 6 Uranium adsorption kinetics test diagram of carboxylated aromatic oxime in Example 2;

[0033] Figure 7 The high temperature gel chromatography test chart of carboxylated aromatic oxime in Example 3;

[0034] Figure 8 Isotherm adsorption curve of carboxylated aromatic oxime in Example 3;

[0035] Fig. 9 This is the high temperature gel chromatography test chart of carboxylated aromatic oxime in Example 4;

[0036] Fig.10 The cross-sectional morphology of the membrane after the carboxylated aromatic oxime in Example 4 was recycled 5 times. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] The present invention provides a carboxylated aromatic oxime compound having a structure shown in Formula I:

[0043]

[0044] The mass average molecular weight Mw of the carboxylated aromatic oxime compound is 70,000 to 250,000.

[0045] The present invention introduces hydrophilic carboxyl groups and selective amidoximes into the main chain of polymer molecules. The hydrophilic carboxyl groups are beneficial to the rapid diffusion of uranyl ions at the phase interface, greatly improving the uranium adsorption kinetics, and can synergistically enrich uranium elements with amidoximes.

[0046] Preferably, the structural formula of the carboxylated aromatic oxime compound is:

[0047]

[0048]

[0049] The present invention also provides a method for preparing the carboxylated aromatic oxime compound, comprising the following steps:

[0050] Under an inert atmosphere, carboxylated bisphenol and difluorocyanide undergo salt formation and polycondensation reactions in sequence to obtain an adsorbent intermediate;

[0051] The adsorbent intermediate is oximated in a hydroxylamine solution to obtain the carboxylated aromatic oxime.

[0052] In some embodiments, the inert atmosphere is preferably nitrogen.

[0053] In some embodiments, the present invention first dissolves carboxylated bisphenol, difluorocyanate and potassium carbonate in a polar aprotic solvent, adds a water-carrying agent, and quickly stirs to form a uniform and transparent mixed solution, and then performs salt formation and polycondensation reactions; the polar aprotic solvent is at least one of dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dimethylacetamide (DMAc); the water-carrying agent is toluene and / or xylene; the carboxylated bisphenol and difluorocyanate are sequentially subjected to salt formation and polycondensation reactions, and the solid content in the system is 10wt% to 15wt%; the molar ratio of the potassium carbonate to the difluorocyanate is 2.5:1, and the function of the potassium carbonate is salt formation.

[0054] In some embodiments, the carboxylated bisphenol is the following monomer c or monomer d:

[0055]

[0056] The following monomer a or monomer b of the difluorocyanate is:

[0057]

[0058] In some embodiments, the molar ratio of the cyanide bisfluoride to the carboxylated bisphenol is 1:1 to 1:1.1.

[0059] In some embodiments, the temperature of the salt formation is 120-135° C., and the time is 2-3 hours; the temperature of the polycondensation is 155-160° C., and the time is 5-6 hours.

[0060] In some embodiments, the present invention firstly crushes the adsorbent intermediate and disperses it in ultrapure water before subsequent oximation. The present invention has no special requirements on the crushing method of the adsorbent intermediate, and a method familiar to those skilled in the art can be used.

[0061] In some embodiments, the amount of hydroxylamine used is 2.5 to 10 times the molar equivalent of the difluorocyanate.

[0062] In some embodiments, the oximation temperature is 60° C. and the time is 48 h.

[0063] The present invention also provides a self-supporting porous uranium adsorbent. The self-supporting porous uranium adsorbent is prepared by subjecting the carboxylated aromatic oxime described in the above technical solution to a non-solvent induced phase separation method (NIPS).

[0064] In some embodiments, the non-solvent induced phase separation method is: dissolving the carboxylated aromatic oxime in a solvent to form a homogeneous solution, then adding a NIPS non-solvent to extract the solvent to form a two-phase structure with the polymer as a continuous phase and the solvent as a dispersed phase, and then removing the solvent to obtain a polymer with a certain pore structure.

[0065] In some embodiments, the solvent is one or more of dimethylacetamide (DMAc), dimethylformamide (DMF), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO); the type of the NIPS non-solvent is one or more of methanol, ethanol, and water; and the temperature during the non-solvent induced phase separation method is 25 to 45°C.

[0066] In some embodiments, the preparation method of the self-supporting porous uranium adsorbent is:

[0067] (1) Under a nitrogen atmosphere, carboxylated bisphenol, difluorocyanate and potassium carbonate are dissolved in a polar aprotic solvent, a water-carrying agent is added, and the mixture is rapidly stirred to form a uniform and transparent mixed solution, and salt is formed and polycondensed under high temperature to obtain an adsorbent intermediate;

[0068] (2) crushing the above-mentioned adsorbent intermediate and dispersing it in ultrapure water, adding hydroxylamine solution at 60° C. for 48 hours to obtain carboxylated aromatic oxime;

[0069] (3) The obtained carboxylated aromatic oxime is dissolved in a solvent to form a homogeneous solution, and then a NIPS non-solvent is added to extract the solvent to form a two-phase structure with the polymer as a continuous phase and the solvent as a dispersed phase. The solvent is then removed to obtain the target adsorbent.

[0070] The present invention also provides the use of the carboxylated aromatic oxime compound or the self-supporting porous uranium adsorbent described in the above technical solution for extracting uranium from seawater.

[0071] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0072] Unless otherwise specified, the reagents or raw materials used in the examples of the present invention were purchased from commercial channels or have been disclosed.

[0073] Example 1

[0074] (1) Under nitrogen atmosphere, 10 mmol of cyanide bisfluoroa, 10 mmol of carboxylated bisphenol c, and 25 mmol of K 2 CO 3 Dissolve in DMSO solvent, add toluene, stir rapidly to form a uniform and transparent mixed solution, heat to 120°C for 2 hours to form salt, continue to heat to 160°C for 5 hours to obtain an adsorbent intermediate;

[0075] (2) crushing the above-mentioned adsorbent intermediate and dispersing it in ultrapure water, adding 25 mL of hydroxylamine solution and performing oximation at 60° C. for 48 h to obtain carboxylated aromatic oxime;

[0076] (3) The carboxylated aromatic oxime is dissolved in DMAc to form a homogeneous solution, and then methanol is added to extract the DMAc to form a two-phase structure with the polymer as the continuous phase and the solvent as the dispersed phase. Then, DMAc is removed to obtain the target adsorbent; the molecular formula is:

[0077]

[0078] Figure 1 This is the high temperature gel chromatography (GPC) diagram of the molecule in Example 1. It can be seen from the figure that the target molecule has a mass average molecular weight Mw = 95,600 and a molecular weight distribution PDI = 1.609, indicating that the obtained adsorbent has a higher molecular weight and the flexibility of the membrane can be guaranteed when the membrane is prepared.

[0079] Figure 2 The FTIR spectra of the adsorbent intermediate and carboxylated aromatic oxime in Example 1 are shown in the figure. As can be seen from the figure, for the FTIR spectrum of the target adsorbent, 3438 cm -1 and 3360cm -1 The stretching vibration peak of amino group appears at 1656cm -1 and 1376cm -1 The NO and CN stretching vibration peaks appeared respectively, proving the existence of amidoxime groups; in addition, both showed aromatic ether bonds (1225 cm -1 and 1010cm -1 ), indicating that the molecular skeleton of the adsorbent remained intact before and after oximation.

[0080] Figure 3 and Figure 4 are respectively the adsorbent intermediate and the carboxylated aromatic oxime in Example 1 1 H NMR spectra. It can be seen from the figure that the hydrogen in each environment of the two polymers is well assigned. The above characterization confirms the successful preparation of the adsorbent.

[0081] The adsorbent of Example 1 was subjected to an adsorption kinetics test, and the test results were similar to those of Example 2. Compared with the traditional PAO type adsorbent, the equilibrium adsorption capacity of the carboxylated aromatic oxime porous membrane obtained by the present invention was increased by more than 300%, and the equilibrium time was within 12 hours.

[0082] The adsorption characteristics of the adsorbent of Example 1 were tested. The test structure was similar to that of Example 3. The uranium adsorption capacity of the target adsorbent could reach more than 490 mg / g.

[0083] The adsorbent of Example 1 was subjected to a cyclic adsorption performance test, and the test results were similar to those of Example 4. After 5 cycles of testing, the basic structure of the target adsorbent remained intact.

[0084] Example 2

[0085] (1) Under nitrogen atmosphere, 10 mmol of cyanide bisfluoroa, 11 mmol of carboxylated bisphenol d, and 25 mmol of K 2 CO 3 Dissolve in DMF solvent, add xylene, stir rapidly to form a uniform and transparent mixed solution, heat to 135°C for 3 hours to form salt, continue to heat to 155°C for 6 hours to obtain an adsorbent intermediate;

[0086] (2) crushing the above-mentioned adsorbent intermediate and dispersing it in ultrapure water, adding 50 mL of hydroxylamine solution and performing oximation at 60° C. for 48 h to obtain carboxylated aromatic oxime;

[0087] (3) The carboxylated aromatic oxime is dissolved in DMF to form a homogeneous solution, and then ethanol is added to extract the DMF to form a two-phase structure with the polymer as the continuous phase and the solvent as the dispersed phase, and then the DMF is removed to obtain the target adsorbent; the molecular formula is:

[0088]

[0089] Figure 5 This is the high temperature gel chromatography (GPC) diagram of the molecule in Example 2. It can be seen from the figure that the target molecule has a mass average molecular weight Mw = 159,000 and a molecular weight distribution PDI = 1.37, indicating that the obtained adsorbent has a higher molecular weight and the flexibility of the membrane can be guaranteed when the membrane is prepared.

[0090] Figure 6 This is a kinetic curve diagram of the target adsorbent in Example 2. It can be seen from the figure that, compared with the traditional PAO type adsorbent, the equilibrium adsorption capacity of the carboxylated aromatic oxime porous membrane obtained by the present invention is increased by 336%, and the equilibrium time is only 12 hours.

[0091] The adsorption characteristics of the adsorbent of Example 2 were tested. The test structure was similar to that of Example 3. The uranium adsorption capacity of the target adsorbent could reach more than 490 mg / g.

[0092] The adsorbent of Example 2 was subjected to a cyclic adsorption performance test, and the test results were similar to those of Example 4. After 5 cycles of testing, the basic structure of the target adsorbent remained intact.

[0093] Example 3

[0094] (1) Under nitrogen atmosphere, 10 mmol of cyanide bisfluoro b, 10.5 mmol of carboxylated bisphenol c, and 25 mmol of K 2 CO 3 Dissolve in DMSO solvent, add toluene, stir rapidly to form a uniform and transparent mixed solution, heat to 130°C for 2.5 hours to form salt, and continue to heat to 150°C for 5.5 hours to obtain an adsorbent intermediate;

[0095] (2) crushing the above-mentioned adsorbent intermediate and dispersing it in ultrapure water, adding 80 mL of hydroxylamine solution and performing oximation at 60° C. for 48 h to obtain carboxylated aromatic oxime;

[0096] (3) The carboxylated aromatic oxime is dissolved in NMP to form a homogeneous solution, and then ethanol is added to extract the NMP to form a two-phase structure with the polymer as the continuous phase and the solvent as the dispersed phase, and then the NMP is removed to obtain the target adsorbent; the molecular formula is:

[0097]

[0098] Figure 7 This is the high temperature gel chromatography (GPC) diagram of the molecule in Example 3. It can be seen from the figure that the target molecule has a mass average molecular weight Mw = 20.76 and a molecular weight distribution PDI = 1.21, indicating that the obtained adsorbent has a higher molecular weight and the flexibility of the membrane can be guaranteed when the membrane is prepared.

[0099] The adsorbent of Example 3 was subjected to an adsorption kinetics test, and the test results were similar to those of Example 2. Compared with the traditional PAO-type adsorbent, the equilibrium adsorption capacity of the carboxylated aromatic oxime porous membrane obtained by the present invention was increased by more than 300%, and the equilibrium time was within 12 hours.

[0100] Figure 8 The isothermal adsorption curve of the carboxylated aromatic oxime in Example 3 is given. According to calculation, the uranium adsorption capacity of the target adsorbent can reach 499 mg / g.

[0101] The adsorbent of Example 3 was subjected to a cyclic adsorption performance test, and the test results were similar to those of Example 4. After 5 cycles of testing, the basic structure of the target adsorbent remained intact.

[0102] Example 4

[0103] (1) Under nitrogen atmosphere, 10 mmol of cyanide bisfluoro b, 10.5 mmol of carboxylated bisphenol d, and 25 mmol of K 2 CO 3 Dissolve in DMAc solvent, add toluene and xylene, stir rapidly to form a homogeneous and transparent mixed solution, heat to 125°C for 2.5 hours to form salt, continue to heat to 160°C for 5.5 hours to obtain an adsorbent intermediate;

[0104] (2) crushing the above-mentioned adsorbent intermediate and dispersing it in ultrapure water, adding 100 mL of hydroxylamine solution and performing oximation at 60° C. for 48 h to obtain carboxylated aromatic oxime;

[0105] (3) The carboxylated aromatic oxime is dissolved in DMSO to form a homogeneous solution, and then ethanol is added to extract the DMSO to form a two-phase structure with the polymer as the continuous phase and the solvent as the dispersed phase, and then the DMSO is removed to obtain the target adsorbent; the molecular formula is:

[0106]

[0107] Fig. 9 This is the high temperature gel chromatography (GPC) diagram of the molecule in Example 4. It can be seen from the figure that the target molecule has a mass average molecular weight Mw = 71,000 and a molecular weight distribution PDI = 1.02, indicating that the obtained adsorbent has a higher molecular weight and the flexibility of the membrane can be guaranteed when the membrane is prepared.

[0108] The adsorbent of Example 4 was subjected to an adsorption kinetics test, and the test results were similar to those of Example 2. Compared with the traditional PAO-type adsorbent, the equilibrium adsorption capacity of the carboxylated aromatic oxime porous membrane obtained by the present invention was increased by more than 300%, and the equilibrium time was within 12 hours.

[0109] The adsorbent of Example 4 was tested for its adsorption characteristics. The test structure was similar to that of Example 3. The target adsorbent had a uranium adsorption capacity of more than 490 mg / g.

[0110] Fig.10 This is a cross-sectional morphology of the membrane after the adsorbent in Example 4 was tested for 5 cycles. It can be seen from the figure that the basic structure of the target adsorbent remains intact after long-term use.

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A self-supporting porous uranium adsorbent, characterized in that: A self-supporting porous uranium adsorbent is prepared by using a carboxylated aromatic oxime compound through a non-solvent induced phase separation method. The carboxylated aromatic oxime compound has a structure shown in Formula I: Formula I; The mass average molecular weight Mw of the carboxylated aromatic oxime compound is 70,000 to 250,000; The preparation method of the carboxylated aromatic oxime compound comprises the following steps: Under an inert atmosphere, carboxylated bisphenol and difluorocyanide undergo salt formation and polycondensation reactions in sequence to obtain an adsorbent intermediate; The adsorbent intermediate is oximated in a hydroxylamine solution to obtain the carboxylated aromatic oxime; The carboxylated bisphenol is: ； The difluorocyanate is:

2. The self-supporting porous uranium adsorbent according to claim 1, characterized in that: The structural formula of the carboxylated aromatic oxime compound is:

3. The self-supporting porous uranium adsorbent according to claim 1, characterized in that: The molar ratio of the cyanide bisfluoride to the carboxylated bisphenol is 1:1 to 1:1.

1.

4. The self-supporting porous uranium adsorbent according to claim 1, characterized in that: The temperature of the salt formation is 120-135° C., and the time is 2-3 hours; the temperature of the polycondensation is 155-160° C., and the time is 5-6 hours.

5. The self-supporting porous uranium adsorbent according to claim 1, characterized in that: The usage amount of the hydroxylamine is 2.5 to 10 times the molar equivalent of the difluorocyanate.

6. The self-supporting porous uranium adsorbent according to claim 1, characterized in that: The oximation temperature is 60°C and the time is 48h.

7. Use of the self-supporting porous uranium adsorbent according to claim 1 to extract uranium from seawater.

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