A functionalized blended ultrafiltration membrane for uranium extraction from seawater and its preparation method
By combining MXenes with gastroxime-polymerized polyacrylonitrile to prepare functionalized blended ultrafiltration membranes, the problems of insufficient adsorption amount and low selectivity in seawater extraction are solved, and efficient and stable uranium adsorption effect is achieved, which is suitable for complex seawater environments.
Patent Information
- Application Number
- CN202210506537.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-05-11
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2042-05-11
AI Technical Summary
The existing adsorbents have problems such as insufficient adsorption, low selectivity and poor adaptability to complex environments during the extraction of uranium in seawater. In particular, MXenes has low selectivity for uranium and is easily disturbed by other ions in seawater.
The functionalized particle MXenes was combined with geminoximetyl polyacrylonitrile to prepare a functionalized blended ultrafiltration membrane. The synergistic effect of MXenes' highly active sites and geminoximetyl groups was used to improve the adsorption amount of uranium and enhance the hydrophilicity and anti-fouling properties of the membrane.
It has achieved high adsorption capacity, good selectivity, stable operation in complex environments, and the materials are environmentally friendly and low-priced, making it suitable for large-scale applications.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of membrane adsorption, and particularly relates to a functionalized blend ultrafiltration membrane for uranium extraction from seawater and a preparation method thereof. Background Art
[0002] Due to its low-carbon characteristics, there is an increasing demand in modern society for nuclear energy as an important alternative energy source to fossil fuels. Uranium resources are the prerequisite for the sustainable development of the nuclear industry. However, only about 6% of the uranium reserves are in terrestrial ores. The increasing consumption rate has led to a serious shortage of uranium fuel in less than a century. Notably, the uranium content in the ocean is approximately 1000 times that in ores. Extracting uranium from seawater is a necessary condition to ensure the long-term and stable power generation of nuclear energy.
[0003] Advanced functional adsorbents play an important role in the economical and efficient extraction of uranium from seawater. However, considering the complex conditions including high ionic strength, various interfering ions, ultra-low uranium concentration (3.3 ppb), and complex biochemical environment, developing adsorbents with high stability, excellent adsorption capacity, and excellent selectivity for uranium in seawater remains a challenge.
[0004] The adsorption method has the advantages of high removal rate, low cost, convenient operation, simple availability, etc., and is currently the most widely used adsorption method. However, developing suitable materials with good adsorption capacity remains a key challenge, and appropriate high-adsorption-capacity adsorbents must be developed to remove radionuclides from harsh environmental conditions. Some advanced functional nanomaterials, such as clay minerals, zeolites, carbon materials, and metal-organic frameworks (MOFs), are limited in their practical applications due to their low adsorption capacity, slow adsorption kinetics, and poor selectivity. In addition, two-dimensional (2D) nanomaterials with a lateral size greater than 100 nm, including graphene, transition metal dichalcogenides (MoS2), and boron nitride, exhibit excellent physical and chemical properties and a high specific surface area. However, their adsorption capacity is very low, and they are not suitable for adsorption applications due to their weak van der Waals bonds.
[0005] MXenes do not have the drawback of weak van der Waals adsorption because they are composed of transition metal elements such as titanium (Ti) and vanadium (V), and have good affinity for heavy metals (lead, chromium, copper, and mercury), organic dyes (methylene blue, methyl green), and radionuclides. Due to the presence of a large number of active sites terminated by numerous functional groups in MXenes, it not only provides sites for direct ion exchange but also effectively adsorbs and immobilizes radionuclides through chemical and electrostatic attraction. More importantly, MXenes exhibit high resistance to strong radiation due to their excellent chemical and thermal stability, which is a prerequisite for a material to be an ideal adsorbent for separating hazardous radionuclides from nuclear waste. However, the selectivity of MXenes for uranium is not very high and it is easily affected by ions such as vanadium in seawater, increasing the difficulty of uranium extraction from seawater.
[0006] In addition, to adsorb uranium from environments with difficult conditions such as seawater, a membrane material with good chemical and mechanical strength is required. Polymers such as polyacrylonitrile have good chemical and mechanical strength but lack appropriate chemical groups to adsorb heavy metals. The amidoximation method of cyanide is the most mature and most reported uranium extraction technology from seawater currently. The earliest amidoxime compound was synthesized in 1884. Amidoxime compounds have been well applied in the field of heavy metal recovery due to their excellent chelating properties for metal ions. Currently, there are many literature reports on the application of amidoxime compounds in this regard, especially their more extensive application in extracting uranium from seawater. However, the single amidoximation method has a low adsorption capacity for uranium and it is difficult to achieve large-scale practical applications. Summary of the Invention
[0007] In order to solve problems such as insufficient adsorption capacity and low selectivity, the present invention provides a preparation method of a functionalized blend ultrafiltration membrane for uranium extraction from seawater, which combines functionalized particles MXenes with amidoximated polyacrylonitrile to achieve their synergistic adsorption effect. For the first time, functionalized particles are combined with functionalized groups to extract uranium, greatly improving the uranium adsorption capacity. In addition, the prepared blend membrane has simple operation, excellent mechanical properties, high pure water flux, good hydrophilicity on the membrane surface, strong anti-fouling performance, excellent physical and chemical properties, and can operate stably for a long time.
[0008] Therefore, the technical solution of the present invention is as follows:
[0009] 1) Preparation of MXenes powder: Slowly add a certain amount of MXenes powder precursor into a container containing an etching agent, stir magnetically, and react in a water bath at 40 - 60 °C for 30 - 48 h. After the reaction, centrifuge the obtained slurry, wash it with deionized water until neutral, and finally collect the precipitate, which is vacuum dried to obtain MXenes powder.
[0010] 2) Preparation of blended ultrafiltration membrane: Powders of MXenes and polyacrylonitrile (PAN) in a certain proportion were added to 80 - 86 wt% solvent, ultrasonically dispersed, heated in a water bath and mechanically stirred for 4 - 12 h, where the water bath temperature was 40 - 80 °C and the mechanical stirring rate was 100 - 400 r / min. After the reaction was completed, degassing was carried out under vacuum, and flat membranes were coated with an automatic film coater, and then immersed in deionized water.
[0011] 3) Preparation of functionalized ultrafiltration membrane: A certain amount of the blended membrane was added to a 20 - 40 g / L hydroxylamine hydrochloride solution, heated in a water bath and reacted for 1 - 5 h, where the water bath temperature was 40 - 80 °C. After the reaction was completed, the surface of the functionalized blended membrane was rinsed with deionized water.
[0012] 4) Uranium extraction from seawater experiment: Adsorption experiments were carried out using uranium solutions with different initial concentrations; the pH was adjusted by HNO3 and NaOH; in the desorption experiment, desorption was carried out with a 1 mol / L HNO3 solution; during the adsorption and desorption processes, the change in the absorbance of the solution was measured using an ultraviolet spectrophotometer, and the adsorption experiment device used a commonly used water flux test device in the laboratory.
[0013] Furthermore, the MXenes powder described in step 1) is one of Ti3C2, Nb2C, V2C, and Mo2C.
[0014] Furthermore, the etching agent described in step 1) is one of hydrofluoric acid (HF), lithium fluoride and hydrochloric acid (LiF + HCl), and ammonium bifluoride (NH4HF2).
[0015] Furthermore, the mass ratio of the MXenes powder precursor to the etching agent in step 1) is 1:8 - 15.
[0016] Furthermore, the mass ratio of the MXenes powder to the PAN powder in step 2) is 1:4 - 32.
[0017] Furthermore, the solvent described in step 2) is one of N,N - dimethylformamide (DMF), N,N - dimethylacetamide (DMAc), or N - methylpyrrolidone (NMP).
[0018] Furthermore, the mass ratio of the blended membrane to hydroxylamine hydrochloride in step 3) is 1:50 - 200.
[0019] Compared with the prior art, the present invention has the following advantages:
[0020] 1) By forming a film by mixing polyacrylonitrile and functional nanoparticles MXenes, the problems of low adsorption capacity and slow adsorption rate of traditional adsorbents are solved, and the added functional particles have excellent properties such as good resistance to complex chemical environments such as acids and bases.
[0021] 2) For the first time, the amidoximated polyacrylonitrile membrane is combined with functional particles, solving the problems of low selectivity of traditional adsorbents and the influence of interfering ions, and achieving the synergistic adsorption effect of particles and chelating groups.
[0022] 3) The ultrafiltration membrane prepared by the present invention has good hydrophilicity, strong anti-fouling performance, a stable surface structure, and can operate stably for a long time. The used MXenes particles are green, environmentally friendly, and inexpensive, with good market prospects. The used amidoximation method is technically mature and widely applied. Description of the Drawings
[0023] Figure 1 Fourier infrared spectra of MXenes precursors and MXenes particles obtained in Example 1
[0024] Figure 2 Scanning electron microscope image of the surface of the ultrafiltration membrane after blending with MXenes particles obtained in Example 1 Detailed Description of the Invention
[0025] The present invention will be further described below with reference to the drawings and examples.
[0026] Examples 1 to 4
[0027] Their preparation processes are basically the same, except that: the ratio of MXenes and polyacrylonitrile (PAN) powders in step 2) is changed.
[0028] 1) Preparation of MXenes powder: Slowly add 3 g of Ti3AlC2 powder into a container containing 40 mL of HF etching agent, stir magnetically, and react in a water bath at 55 °C for 36 h. After the reaction, centrifuge the obtained slurry, wash it with deionized water until neutral, and finally collect the precipitate, which is vacuum dried to obtain MXenes powder.
[0029] 2) Preparation of the blended ultrafiltration membrane: Add MXenes and polyacrylonitrile (PAN) powders in the ratio shown in Table 1 to 84 wt% DMAc, disperse them ultrasonically, heat in a water bath and mechanically stir for 12 h, where the water bath temperature is 60 °C and the mechanical stirring rate is 300 r / min. After the reaction, remove the bubbles under vacuum, coat a flat membrane with an automatic film coater, and then soak it in deionized water.
[0030] 3) Uranium extraction from seawater experiment: The adsorption experiment is carried out using uranium solutions with different initial concentrations; the pH is adjusted by HNO3 and NaOH; in the desorption experiment, 1 mol / L HNO3 solution is used for desorption; the absorbance changes of the solution during the adsorption and desorption processes are measured using an ultraviolet spectrophotometer, and the adsorption experiment device uses a commonly used water flux test device in the laboratory.
[0031] FromFigure 1 It can be seen that after etching, a new peak appears in the MXenes at 598 cm -1 and a new peak appears, which belongs to the vibration peak of the Ti-O bond. A broad peak appears around 3410 cm -1 which belongs to the stretching vibration peak of -OH, indicating that MXenes has been successfully etched. Figure 2 Figure 2 is the SEM image of the surface of the ultrafiltration membrane after blending, which reflects the surface morphology of the polyacrylonitrile membrane after blending.
[0032] Table 1 Specific implementation schemes of Examples 1-4
[0033]
[0034] It can be seen from Examples 1-4 that when the ratio of MXenes to polyacrylonitrile (PAN) powder is 1:8, the mechanical properties of the membrane are the best, the water flux is medium, the adsorption capacity is large, and the membrane blending uniformity is good.
[0035] Examples 5-9
[0036] The preparation process is basically the same, except that: the water bath heating reaction time in step 3) is changed.
[0037] 1) Preparation of MXenes powder: Slowly add 3 g of Ti3AlC2 powder into a container containing 40 mL of HF etching agent, stir magnetically, and react in a water bath at 55 °C for 36 h. After the reaction, centrifuge the obtained slurry, wash it with deionized water until neutral, and finally collect the precipitate, which is vacuum dried to obtain MXenes powder.
[0038] 2) Preparation of blended ultrafiltration membrane: Blend MXenes and polyacrylonitrile (PAN) powder at a blending ratio of 1:8 into 84 wt% DMAc solvent, disperse it by ultrasonic wave, heat it in a water bath and stir mechanically for 12 h, where the water bath temperature is 60 °C and the mechanical stirring rate is 300 r / min. After the reaction, remove the bubbles under vacuum, coat a flat membrane with an automatic film coater, and then soak it in deionized water.
[0039] 3) Preparation of functionalized ultrafiltration membrane: Add 1 g of the blended membrane into 100 g of 30 g / L hydroxylamine hydrochloride solution, and the water bath heating reaction time is shown in Table 2, where the water bath temperature is 60 °C. After the reaction, rinse the surface of the functionalized blended membrane with deionized water.
[0040] 4) Uranium extraction from seawater experiment: Adsorption experiments were conducted using uranium solutions with different initial concentrations; the pH was adjusted with HNO3 and NaOH; in the desorption experiment, desorption was carried out with 1 mol / L HNO3 solution; the absorbance changes of the solution were measured by an ultraviolet spectrophotometer during both the adsorption and desorption processes, and the adsorption experiment device used a commonly used water flux test device in the laboratory.
[0041] Table 2 Specific implementation schemes of Examples 5 - 9
[0042]
[0043] As can be seen from Examples 5 - 9, when the water bath heating reaction time is 3 h, the adsorption capacity is the highest, the pure water flux is relatively high, and at this time, the internal structure of the membrane is better and the degree of membrane pore collapse is lower.
[0044] Comparative Example 1
[0045] 1) Preparation of ultrafiltration membrane: Polyacrylonitrile (PAN) powder was added to 84 wt% DMAc solvent, ultrasonically dispersed, heated in a water bath and mechanically stirred for 12 h, where the water bath temperature was 60 °C and the mechanical stirring rate was 300 r / min. After the reaction was completed, vacuum degassing was carried out, and a flat membrane was coated with an automatic film coater, and then immersed in deionized water.
[0046] 2) Uranium extraction from seawater experiment: Adsorption experiments were conducted using uranium solutions with different initial concentrations; the pH was adjusted with HNO3 and NaOH; in the desorption experiment, desorption was carried out with 1 mol / L HNO3 solution; the absorbance changes of the solution were measured by an ultraviolet spectrophotometer during both the adsorption and desorption processes, and the adsorption experiment device used a commonly used water flux test device in the laboratory.
[0047] Comparative Example 2
[0048] 1) Preparation of ultrafiltration membrane: Polyacrylonitrile (PAN) powder was added to 84 wt% DMAc solvent, ultrasonically dispersed, heated in a water bath and mechanically stirred for 12 h, where the water bath temperature was 60 °C and the mechanical stirring rate was 300 r / min. After the reaction was completed, vacuum degassing was carried out, and a flat membrane was coated with an automatic film coater, and then immersed in deionized water.
[0049] 2) Preparation of functionalized ultrafiltration membrane: 1 g of ultrafiltration membrane was added to 100 g of 30 g / L hydroxylamine hydrochloride solution, and heated in a water bath for 3 h, where the water bath temperature was 60 °C. After the reaction was completed, the surface of the functionalized ultrafiltration membrane was rinsed with deionized water.
[0050] 3) Uranium extraction from seawater experiment: Adsorption experiments were conducted using uranium solutions with different initial concentrations; the pH was adjusted with HNO3 and NaOH; in the desorption experiment, desorption was carried out with a 1 mol / L HNO3 solution; the changes in the absorbance of the solution during the adsorption and desorption processes were measured using an ultraviolet spectrophotometer, and the adsorption experiment device used a commonly used water flux test device in the laboratory.
[0051] The adsorption capacity and pure water flux of Examples 3 and 7 and Comparative Examples 1 and 2 were tested, and the data are shown in Table 3.
[0052] Table 3 Specific implementation schemes of Examples 3 and 7 and Comparative Examples 1 and 2
[0053]
[0054] It can be seen from the above table that the functionalized blend ultrafiltration membrane prepared under the optimal conditions in Example 7 has a relatively higher adsorption capacity compared to the pure PAN membrane in Comparative Example 1, the single-functionalized PAN membrane in Comparative Example 2, and the single MXenes and PAN blend membrane in Example 3, indicating that the two achieve a synergistic adsorption effect.
[0055] Although the present invention has been described above in conjunction with the accompanying drawings and tables, the present invention is not limited to the above-mentioned manner. As long as various improvements are made by adopting the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.
Claims
1. A preparation method of a functionalized blend ultrafiltration membrane for uranium extraction from seawater, characterized in that It includes the following steps: 1) Preparation of MXenes powder: Slowly add a certain amount of MXenes powder precursor into a container filled with an etching agent, stir magnetically, and react in a water bath at a heating temperature of 40 - 60°C for 30 - 48 h. After the reaction, centrifuge the obtained slurry, wash it with deionized water until neutral, and finally collect the precipitate, which is vacuum-dried to obtain MXenes powder; 2) Preparation of the blended ultrafiltration membrane: Add a certain proportion of MXenes and polyacrylonitrile (PAN) powder into 80 - 86 wt% solvent, disperse ultrasonically, react in a water bath with mechanical stirring for 4 - 12 h, where the water bath temperature is 40 - 80°C and the mechanical stirring rate is 100 - 400 r / min. After the reaction is completed, remove air bubbles under vacuum, coat a flat membrane with an automatic film coater, and then soak it in deionized water; 3) Preparation of the functionalized ultrafiltration membrane: Add a certain amount of the blended membrane into a 20 - 40 g / L hydroxylamine hydrochloride solution, react in a water bath at a temperature of 40 - 80°C for 1 - 5 h. After the reaction is completed, rinse the surface of the functionalized blended membrane with deionized water; 4) Uranium extraction from seawater experiment: The adsorption experiment is carried out using uranium solutions with different initial concentrations; the pH is adjusted by HNO3 and NaOH; in the desorption experiment, desorption is carried out with a 1 mol / L HNO3 solution; the absorbance change of the solution during the adsorption and desorption processes is measured using an ultraviolet spectrophotometer, and the adsorption experiment device uses a commonly used water flux test device in the laboratory.
2. The preparation method of a functionalized blended ultrafiltration membrane for uranium extraction from seawater according to claim 1, characterized in that: The MXenes powder described in step 1) is one of Ti3C2, Nb2C, V2C, and Mo2C.
3. The preparation method of a functionalized blended ultrafiltration membrane for uranium extraction from seawater according to claim 1, characterized in that: The etching agent described in step 1) is one of hydrofluoric acid (HF), lithium fluoride and hydrochloric acid (LiF + HCl), and ammonium bifluoride (NH4HF2).
4. The preparation method of a functionalized blend ultrafiltration membrane for uranium extraction from seawater according to claim 1, characterized in that: The mass ratio of the MXenes powder precursor to the etching agent in step 1) is 1:8 - 15.
5. The preparation method of a functionalized blended ultrafiltration membrane for uranium extraction from seawater according to claim 1, characterized in that: The mass ratio of the MXenes powder to the PAN powder in step 2) is 1:4 - 32.
6. The preparation method of a functionalized blend ultrafiltration membrane for uranium extraction from seawater according to claim 1, characterized in that: The solvent described in step 2) is one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), or N-methylpyrrolidone (NMP).
7. The preparation method of a functionalized blended ultrafiltration membrane for uranium extraction from seawater according to claim 1, characterized in that: The mass ratio of the blended membrane to hydroxylamine hydrochloride in step 3) is 1:50 - 200.