Preparation method of graphene-based hydrogel for uranium extraction

Abstract

The invention discloses a preparation method of graphene-based hydrogel for uranium extraction. The preparation method comprises the following steps: preparing functionalized graphene oxide; s2, dissolving N-isopropylacrylamide, N, N '-methylene bisacrylamide, 2-methacryloyloxyethyl phosphorylcholine and the functionalized graphene oxide prepared in the step S1 in distilled water to obtain a mixed solution; adding tetramethylethylenediamine and potassium persulfate into the obtained mixed solution, heating and stirring, reacting in nitrogen, and placing in an ice bath after the reaction is completed, so as to obtain the graphene-based hydrogel. Graphene oxide is introduced, due to the two-dimensional structure of graphene oxide nanosheets and the strong hydrogen bond interaction between graphene oxide and an NIPAM chain, the graphene-based hydrogel has good mechanical properties and excellent chemical stability, and the graphene-based hydrogel serving as an efficient adsorbent of uranium can remarkably improve the selectivity and adsorption capacity of uranium.

Description

Technical Field

[0001] The present invention relates to the technical field of uranium adsorption, and in particular to a method for preparing a graphene-based hydrogel for uranium extraction. Background Art

[0002] Nuclear energy is a sustainable energy source that does not release greenhouse gases, has high energy density and high efficiency, and is expected to replace traditional fossil fuels in most countries. The nuclear industry will inevitably produce a large amount of uranium-containing wastewater. Among the existing chemical separation technologies, adsorption has been proven to be an adaptable, reliable method that is harmless to the environment. It is very important to design uranium adsorption materials with high efficiency. However, the existing uranium adsorption materials have certain limitations: (1) Low adsorbent efficiency. The existing adsorbent materials have low adsorption efficiency for uranium in seawater and salt lake brine, resulting in a longer uranium extraction process. Since the concentration of uranium in seawater and salt lake brine is relatively low, it is difficult to extract uranium. The selectivity and adsorption capacity of the adsorbents of the existing technology for uranium still need to be improved; (2) Poor durability and regeneration performance. Many adsorbents have limited service life in the process of uranium extraction from seawater and salt lake brine. After multiple adsorption-desorption processes, the adsorption performance is significantly reduced. (1) The adsorption efficiency of uranium ions has decreased significantly, and adsorbents with poor regeneration performance need to be replaced frequently, which increases operating costs and operational complexity; (2) The anti-interference ability is insufficient. Seawater contains a variety of other metal ions, such as calcium, magnesium, sodium, etc. These ions will compete with uranium ions for adsorption sites, reducing the adsorption efficiency of uranium; the existing adsorbents are not very selective for uranium ions and are easily interfered by other components in seawater and salt lake brine; (3) The cost is high. The synthesis cost of existing adsorbents is high, especially in large-scale industrial applications. Economic efficiency is still a major challenge. The high production, operation and maintenance costs restrict the widespread application of uranium extraction technology.

[0003] Graphene oxide (GO) is a two-dimensional nanomaterial composed of functionalized sp 2 It is composed of hybrid carbon atoms and has a huge network structure. Its surface is randomly distributed with hydroxyl and epoxy groups, and its edges have carboxyl groups, which makes it an ideal matrix for adsorption. Therefore, the development of graphene-based adsorption materials is of great significance for the efficient extraction of uranium. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention aims to develop a method for preparing a graphene-based hydrogel for uranium extraction. The prepared graphene-based hydrogel can significantly improve the selectivity and adsorption capacity for uranium, shorten the uranium extraction time, and thus improve the economy and feasibility of uranium extraction, so as to solve the problems of low adsorption efficiency, poor durability and regeneration performance, insufficient anti-interference ability and high cost in existing uranium adsorbent technology.

[0005] In order to solve the above problems, the present invention first provides a method for preparing a graphene-based hydrogel for uranium extraction, characterized in that the preparation method comprises the following steps:

[0006] S1. Preparation of functionalized graphene oxide (GO);

[0007] S2, dissolving N-isopropylacrylamide (NIPAM), N,N'-methylenebisacrylamide (MBA), 2-methacryloyloxyethylphosphorylcholine (MPC) and the functionalized graphene oxide prepared in step S1 in distilled water to obtain a mixed solution;

[0008] S3. Add tetramethylethylenediamine (TEMED) and potassium persulfate to the mixed solution obtained in step S2, heat and stir, and react under nitrogen. After the reaction is completed, place in an ice bath to obtain a graphene-based hydrogel.

[0009] Preferably, the method for preparing the functionalized graphene oxide comprises the following steps:

[0010] S4, stirring graphite powder and H2SO4 in an ice bath, then adding potassium permanganate to react for a period of time to obtain a first reaction solution;

[0011] S5, heating the first reaction solution, adding distilled water, keeping warm and stirring, then adding hydrogen peroxide and distilled water, keeping warm and stirring again to obtain a warm solution;

[0012] S6. Rinse the warm solution obtained in step S5 with water until the pH is 7 to obtain functionalized graphene oxide.

[0013] Preferably, in step S2, the mass ratio of N-isopropylacrylamide, 2-methacryloyloxyethyl phosphorylcholine and functionalized graphene oxide is 10:2.9:1-6.

[0014] Preferably, in step S2, the mass ratio of N,N'-methylenebisacrylamide to functionalized graphene oxide is 0.3:1-6.

[0015] Preferably, in step S3, the mass ratio of tetramethylethylenediamine, potassium persulfate and functionalized graphene oxide is 1:1-1.5:5-5.5.

[0016] Preferably, the temperature for heating and stirring in step S3 is 40-60° C., and the reaction time under nitrogen is 20-60 min.

[0017] Preferably, in step S4, the reaction temperature is 0-3°C and the reaction time is 3 hours.

[0018] Preferably, in step S5, the temperature of the heat preservation and stirring is 40-60° C., and the stirring time is 10-20 minutes.

[0019] Preferably, in step S5, the concentration of hydrogen peroxide is 5%, and the mass ratio of the added amount to the graphite powder is 60:1.

[0020] The present invention also provides a graphene-based hydrogel for uranium extraction, which is characterized in that it is prepared by the above-mentioned preparation method.

[0021] The present invention provides a method for preparing a graphene-based hydrogel for uranium extraction. The method uses N-isopropylacrylamide (NIPAM) and 2-methacryloyloxyethylphosphorylcholine (MPC) as raw materials, exhibiting good physical and chemical stability. Functionalized graphene oxide (GO) is also utilized to endow GO with abundant uranium anchoring active sites, thereby synthesizing a graphene-based hydrogel with photothermal conversion and antibacterial properties. The present invention introduces GO. Due to the two-dimensional structure of graphene oxide nanosheets and the strong hydrogen bonding interaction between graphene oxide and NIPAM chains, the graphene-based hydrogel exhibits good mechanical properties and excellent chemical stability. As a highly efficient adsorbent for uranium, the hydrogel can significantly improve uranium selectivity and adsorption capacity, shorten uranium extraction time, and improve adsorption efficiency. The hydrogel also exhibits good stability and recyclability, and has strong resistance to biofouling, making it suitable for extracting uranium from seawater and salt lake brine. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart of the preparation process of the graphene-based hydrogel provided by the present invention;

[0023] Figure 2 In the figure, (a) and (d) are scanning electron microscope images of PNIPAM; (b) and (e) are scanning electron microscope images of PNG-5; (c) and (f) are scanning electron microscope images of PNGM-5; (g) is the FTIR (Fourier transform infrared spectrum) of GO, PNIPAM, MPC, PNG-5 and PNGM-5; (h) is the Raman spectrum of GO and PNGM-5; (i) is the XRD pattern of GO and PNGM-5;

[0024] Figure 3 In the figure, (a) is a diagram showing the adsorption performance of PNGM gels with different graphene oxide contents under dark light conditions; (b) is a diagram showing the effect of pH on the adsorption of PNIPAM, GO, PNGM-5, and PNGM-5 under dark light conditions; (c) is a diagram showing the adsorption capacity of graphene oxide, PNIPAM, and PNGM-5 under different uranium concentrations; (d) is a diagram showing the removal rates of graphene oxide, PNIPAM, and PNGM-5 under different uranium concentrations;

[0025] Figure 4This is the recycling test chart of PNGM-5, the horizontal axis represents the number of cycles, and the vertical axis represents the uranium removal rate;

[0026] Figure 5 This is the adsorption capacity diagram of PNGM-5 in natural seawater for 30 days. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0028] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "top", "bottom", "top surface", "bottom surface", "inside", "outside", "inside", "outside" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The terms "first," "second," and "third" are used solely for descriptive purposes and to distinguish technical features. They are not to be construed as indicating or implying relative importance, or as implicitly specifying the number or order of the technical features indicated.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified or limited, the terms "installed," "connected," "connected," and "set" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances. The following describes an embodiment of the present invention based on its overall structure.

[0031] Figure 1 For the preparation process flow chart of the graphene-based hydrogel provided by the present invention, refer to Figure 1A method for preparing a graphene-based hydrogel for uranium extraction, characterized in that the preparation method comprises the following steps:

[0032] S1. Preparation of functionalized graphene oxide;

[0033] S2, dissolving N-isopropylacrylamide (NIPAM), N,N'-methylenebisacrylamide (MBA), 2-methacryloyloxyethylphosphorylcholine (MPC) and the functionalized graphene oxide prepared in step S1 in distilled water to obtain a mixed solution;

[0034] Wherein, in step S2, the mass ratio of N-isopropylacrylamide, 2-methacryloyloxyethyl phosphorylcholine and functionalized graphene oxide is 10:2.9:1-6; the mass ratio of N,N'-methylenebisacrylamide and functionalized graphene oxide is 0.3:1-6;

[0035] S3, adding tetramethylethylenediamine (TEMED) and potassium persulfate to the mixed solution obtained in step S2, heating and stirring, and reacting under nitrogen. After the reaction is completed, placing in an ice bath to obtain a graphene-based hydrogel;

[0036] The mass ratio of tetramethylethylenediamine, potassium persulfate and functionalized graphene oxide is 1:1-1.5:5-5.5; the heating and stirring temperature is 40-60° C., and the reaction time under nitrogen is 20-60 min.

[0037] In a preferred embodiment, the method for preparing the functionalized graphene oxide comprises the following steps:

[0038] S4, stirring graphite powder and H2SO4 in an ice bath, then adding potassium permanganate to react for a period of time to obtain a first reaction solution;

[0039] The reaction temperature is 0-3°C and the reaction time is 3h;

[0040] S5, heating the first reaction solution, adding distilled water, keeping warm and stirring, then adding hydrogen peroxide and distilled water, keeping warm and stirring again to obtain a warm solution;

[0041] The temperature of the heat preservation and stirring is 40-60° C., and the stirring time is 10-20 min. The concentration of the hydrogen peroxide is 5%, and the mass ratio of the added amount to the graphite powder is 60:1.

[0042] S6. Rinse the warm solution obtained in step S5 with water until the pH is 7 to obtain functionalized graphene oxide.

[0043] A graphene-based hydrogel for uranium extraction is prepared by the above-mentioned preparation method.

[0044] The raw material of the present invention is N-isopropylacrylamide (NIPAM, 98%, MW: 113.16 g·mol -1 ), potassium persulfate (K2S2O8, 99%, MW: 270.32 g·mol -1 ), graphite powder, N,N,N',N'-tetramethylethylenediamine (TEMED, 99%, MW: 116.20 g mol -1 ), sulfuric acid (H2SO4, 70%, MW: 98.08 g·mol -1 ), hydrogen peroxide (H2O2, 30 wt%, MW: 34.01 g·mol -1 ), potassium permanganate (KMnO4, 99%, MW: 158.03 g·mol -1 ), N,N'-methylenebisacrylamide (MBA, 97%, MW: 154.17 g·mol -1 ) and 2-methacryloyloxyethyl phosphorylcholine (MPC, >96%, MW: 295.27 g·mol -1 ) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the materials and reagents used were not further purified.

[0045] Example 1

[0046] (1) Preparation of functionalized graphene oxide: 5 g of graphite powder and 115 mL of H2SO4 were stirred in an ice bath for 1 h. 30 g of KMnO4 was slowly added to the above solution and reacted at 0-3°C for 3 h. The solution was then heated to 50±5°C and stirred for 45 min. 400 mL of H2O was added and stirred for 15 min, with the temperature maintained at 50±5°C. Finally, 300 mL of H2O and 360 g (5%) of H2O2 were added and stirred for 15 min. The warm solution was then rinsed with H2O until pH = 7 to obtain GO.

[0047] (2) Preparation of PNG hydrogel

[0048] Take 0.820g NIPAM, 0.025g MBA and an appropriate amount of 0.082g GO from step (1), add them to 10mL distilled water and stir until homogeneous and transparent. The solution reacts at 50℃. After the reaction is completed, the mixed solution is cooled to room temperature. Then, 20μL of TEMED and 0.020g of KPS are added to the solution and reacted under N2 atmosphere for 30min. Finally, the gel is placed in an ice bath for 2h to obtain PNG hydrogel, which is named PNG-1.

[0049] (3) Preparation of PNGM hydrogel

[0050] 0.820 g NIPAM, 0.025 g MBA, 0.237 g MPC, and an appropriate amount of 0.082 g GO from step (1) were dissolved in 10 mL of distilled water and stirred at 50°C until the solution was homogeneous and transparent. The solution was naturally cooled to room temperature. 20 μL of TEMED and 0.020 g of KPS were added to the above solution and reacted under a nitrogen atmosphere for 30 min. The gel was then placed in an ice bath for 2 h to obtain a PNGM hydrogel, designated PNGM-1.

[0051] After experimental verification, the amount of each raw material is controlled within a certain upper and lower floating range, and the performance of the prepared composite material hydrogel is at the same level, wherein the mass amount of functionalized graphene oxide added in steps (2) and (3) is (0.082g~0.492g); the heating temperature range of stirring in steps (2) and (3) is (40~60℃); the reaction time in nitrogen atmosphere in steps (2) and (3) is (20~60min), preferably, the reaction time in nitrogen atmosphere is 30min.

[0052] Example 2

[0053] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (2) to 0.164 g to prepare a composite hydrogel, which was designated as PNG-2.

[0054] Example 3

[0055] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (2) to 0.246 g to prepare a composite hydrogel, which was designated as PNG-3.

[0056] Example 4

[0057] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (2) to 0.328 g to prepare a composite hydrogel, which was designated as PNG-4.

[0058] Example 5

[0059] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (2) to 0.410 g to prepare a composite hydrogel, which was designated as PNG-5.

[0060] Example 6

[0061] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (2) to 0.492 g to prepare a composite hydrogel, which was designated as PNG-6.

[0062] Example 7

[0063] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (3) to 0.164 g to prepare a composite hydrogel, which was designated as PNGM-2.

[0064] Example 8

[0065] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (3) to 0.246 g to prepare a composite hydrogel, which was designated as PNGM-3.

[0066] Example 9

[0067] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (3) to 0.328 g to prepare a composite hydrogel, which was designated as PNGM-4.

[0068] Example 10

[0069] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (3) to 0.410 g to prepare a composite hydrogel, which was designated as PNGM-5.

[0070] Example 11

[0071] The same method as in Example 1 was used to adjust the content of graphene oxide (GO) in step (3) to 0.492 g to prepare a composite hydrogel, which was designated as PNGM-6.

[0072] Example 12

[0073] 0.820 g of NIPAM and 0.025 g of MBA were dissolved in 10 mL of distilled water, heated to 50°C, stirred until the solution became homogeneous and transparent, and then cooled to room temperature. 20 μL of TEMED and 0.020 g of KPS were added to the above solution and reacted under a nitrogen atmosphere for 30 minutes. The mixture was then placed in an ice bath for 2 hours to produce a composite hydrogel, designated as PNIPAM gel.

[0074] Example 5 Structure and Performance Verification

[0075] The microstructures of PNIPAM, PNG-5 and PNGM-5 were studied by scanning electron microscopy. Figure 2 It shows different network structures of the three gels, and the gel network gradually becomes denser with the increase of GO and MPC content.

[0076] Fourier transform infrared spectroscopy (FTIR) confirmed the successful preparation of graphene oxide, PNIPAM, PNG-5 and PNGM-5, e.g. Figure 2 (g) The stretching vibration peak of C=O graphene oxide is at 1650cm -1 、CO is 1108cm-1 and -OH at 3434 cm -1 There is a broad and strong stretching vibration peak. PNIPAM appears at 3434cm due to the stretching vibration of -NH -1 The peak appears at 1650cm -1 Around 1535 cm, representing the carbonyl group in acrylamide, and the bending vibration of -NH appears at 1535 cm -1 In the FT-IR spectrum of MPC, the -1 Two peaks were observed at + (CH3)3 bending vibration and P=O bending vibration of CH. In the FT-IR of PNG-5, at 3434cm -1 The peak at 1650 cm represents the -OH of GO and the -NH of PNIPAM. -1 The C=O stretching vibration peaks of PNIPAM and GO are 1108 cm -1 The stretching vibration peaks at 3434 cm are from the CO peaks of GO, which indicate that GO is combined with PNIPAM. -1 The peaks at 1650 and 1108 cm-1 are attributed to -OH of GO and -NH of PNIPAM, while the peaks at 1650 and 1108 cm-1 are attributed to -OH of GO and -NH of PNIPAM, respectively. -1 The peaks at 1457 and 1130 cm-1 are attributed to the stretching vibrations of PNIPAM, C=O of GO and CO of GO. The FT-IR spectrum of PNGM-5 shows the characteristic peaks of MPC at 1457 and 1130 cm-1. -1 The successful synthesis of PNGM-5 gel was confirmed. The Raman spectra of GO and PNGM-5 are shown in Figure 2. Figure 2 (h) shows distinct D-band and G-band features, corresponding to the sp 3 Hybridized carbon atoms and sp 2 Hybridized carbon atoms. I of PNGM-5 D / I G The intensity ratio (0.92) is higher than that of GO (0.81), which is due to the increased structural disorder of PNGM-5. The results show that NIPAM and MPC are successfully grafted on the surface of GO. XRD was performed to characterize GO and PNGM-5. The results are shown in Figure 2. Figure 2 (i). The peak at 11.4° is attributed to the (001) crystal plane of GO, with an interlayer spacing of 0.7793 nm, while the (002) diffraction plane of GO appears as a broad, weak diffraction peak at 22.5°. In the diffraction pattern of the PNGM-5 composite material, a broad diffraction peak appears at 26.7° due to the modification of the GO surface by the amorphous structure of NIPAM and MPC, indicating that NIPAM and MPC are successfully bound to GO.

[0077] Based on the above embodiments and accompanying drawings, the present invention provides a method for preparing a graphene-based hydrogel for uranium extraction, which uses N-isopropylacrylamide (NIPAM) and 2-methacryloyloxyethylphosphorylcholine (MPC) as raw materials, has good physical / chemical stability, and also utilizes functionalized graphene oxide (GO) to give GO rich uranium anchoring active sites, synthesizing a graphene-based hydrogel with photothermal conversion and antibacterial properties. The present invention introduces GO. Due to the two-dimensional structure of graphene oxide nanosheets and the strong hydrogen bond interaction between graphene oxide and NIPAM chains, the graphene-based hydrogel exhibits good mechanical properties and excellent chemical stability. As an efficient adsorbent for uranium, it can significantly improve the selectivity and adsorption capacity for uranium, shorten the uranium extraction time, and improve the adsorption efficiency. At the same time, it has good stability and recyclability, and has strong anti-biological contamination performance, and can be used to extract uranium from seawater and salt lake brine.

[0078] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for preparing a graphene-based hydrogel for uranium extraction, characterized in that: The preparation method comprises the following steps: S1. Preparation of functionalized graphene oxide; S2, dissolving N-isopropylacrylamide, N,N'-methylenebisacrylamide, 2-methacryloyloxyethyl phosphorylcholine and the functionalized graphene oxide prepared in step S1 in distilled water to obtain a mixed solution; S3. Add tetramethylethylenediamine and potassium persulfate to the mixed solution obtained in step S2, heat and stir, and react under nitrogen. After the reaction is completed, place in an ice bath to obtain a graphene-based hydrogel.

2. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 1, wherein: The preparation method of the functionalized graphene oxide comprises the following steps: S4, stirring graphite powder and H2SO4 in an ice bath, then adding potassium permanganate to react for a period of time to obtain a first reaction solution; S5, heating the first reaction solution, adding distilled water, keeping warm and stirring, then adding hydrogen peroxide and distilled water, keeping warm and stirring again to obtain a warm solution; S6. Rinse the warm solution obtained in step S5 with water until the pH is 7 to obtain functionalized graphene oxide.

3. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 1, wherein: In step S2, the mass ratio of N-isopropylacrylamide, 2-methacryloyloxyethyl phosphorylcholine and functionalized graphene oxide is 10:2.9:1-6.

4. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 1, wherein: In step S2, the mass ratio of N,N'-methylenebisacrylamide to functionalized graphene oxide is 0.3:1-6.

5. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 1, characterized in that: In step S3, the mass ratio of tetramethylethylenediamine, potassium persulfate and functionalized graphene oxide is 1:1-1.5:5-5.

5.

6. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 1, characterized in that: The temperature of heating and stirring in step S3 is 40-60° C., and the reaction time under nitrogen is 20-60 min.

7. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 2, wherein: In the step S4, the reaction temperature is 0-3°C and the reaction time is 3 hours.

8. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 2, wherein: In step S5, the temperature of the heat preservation and stirring is 40-60° C., and the stirring time is 10-20 minutes.

9. The method for preparing a graphene-based hydrogel for uranium extraction according to claim 2, characterized in that: In step S5, the concentration of hydrogen peroxide is 5%, and the mass ratio of the added amount to the graphite powder is 60:

1.

10. A graphene-based hydrogel for uranium extraction, characterized in that: The preparation method is as described in any one of claims 1 to 9.

Images