Magnetic hydrogel microspheres with both uranium extraction and detection functions and preparation method thereof

Abstract

The present invention belongs to the field of new material preparation, discloses a magnetic hydrogel microsphere with both uranium extraction and detection functions and its preparation method, the preparation method comprises the following steps: (1) adding a photopolymerization monomer, a photoinitiator, and a cross-linking agent to deionized water to obtain a prepolymer solution; (2) uniformly mixing the prepolymer solution, a magnetic material, a metal organic framework material and deionized water to obtain an aqueous phase solution; the metal organic framework material is any one of ZIF-8, ZIF-67, ZIF-90, and MOF-5; (3) adding an emulsifier to an oil phase solvent to obtain an oil phase part; then, uniformly mixing the aqueous phase solution and the oil phase part to obtain an oil-in-water emulsion; (4) subjecting the oil-in-water emulsion to ultraviolet irradiation to fully gelate it; and then washing to obtain the magnetic hydrogel microsphere. The magnetic hydrogel microspheres in the present invention have excellent uranium adsorption performance, can simultaneously realize uranium extraction and detection, and have important significance and practical value.

Description

Technical Field

[0001] The present invention belongs to the field of new material preparation, and more specifically, relates to a magnetic hydrogel microsphere with both uranium extraction and detection functions and a preparation method thereof. Background Art

[0002] With the rapid development of the global economy, humanity's demand for energy is growing. Nuclear energy, with its advantages of not emitting greenhouse gases or other toxic gases, is considered one of the most promising future energy sources. Uranium is currently the most important nuclear fuel, but terrestrial uranium reserves are far from meeting the global demand for uranium in industry, agriculture, defense, and other fields. The search for alternative uranium sources is urgent. To address this issue, many countries have turned their attention to seawater. Although the concentration of uranium in seawater is relatively low, the total resource reserves are enormous, approximately 4.5 billion tons. Therefore, extracting uranium from seawater is bound to become a key solution to the uranium shortage.

[0003] To extract uranium from seawater, researchers have explored a variety of methods, including chemical precipitation, ion exchange, evaporation and concentration, membrane separation, and adsorption. After years of research, adsorption has become recognized as an efficient and ideal uranium extraction method due to its simplicity, cost-effectiveness, and wide adaptability. This method primarily relies on the interaction between the adsorbent and the adsorbate, allowing uranyl ions to adhere to the adsorbent surface, thereby extracting uranium. Common adsorbents studied can be broadly divided into two categories: inorganic and organic. Inorganic adsorbents primarily include metal oxides, clay minerals, and layered metal sulfides. These adsorbents offer advantages such as simple preparation, ease of elution, and recovery. However, while adsorbing uranium ions, inorganic adsorbents' adsorption sites are also susceptible to complexation with other metal ions, significantly reducing their selectivity for uranium in the complex environment of seawater and severely limiting the development of uranium adsorption. Organic adsorbents primarily include chitosan, synthetic polymers, and engineered proteins. Polymer-based adsorption materials have become the most promising adsorption materials due to their inherent structural advantages, such as the presence of a large number of -OH, -CONH2, -NH2, -COOH and other functional groups in the molecules that can firmly bind to uranyl ions.

[0004] Traditional adsorption methods are often in situ adsorption, and adsorbent materials are often processed into macroscopic bulk materials. However, based on the principle of surface adsorption, the adsorbent material's active area is limited to the surface, and the adsorption sites distributed internally are unable to function. As a result, it has disadvantages such as low adsorption efficiency and slow adsorption rate. In recent years, with the rise of micro-nanotechnology, micro-nanomaterials have developed rapidly. The micro-nanoscale effect has brought many novel properties, such as high surface activity, high surface energy, and high specific surface area, which makes its performance significantly different from that of macroscopic bulk materials. These properties have created more possibilities in the environmental field, such as adsorbents and catalysts. Magnetic micro-nanomaterials not only retain the excellent properties of micro-nanomaterials, but also break passive diffusion due to their magnetic drive properties, realizing active extraction and transportation. Therefore, the design of magnetic micro-nanoadsorbents is expected to improve the adsorption capacity and adsorption rate of adsorbents and endow the materials with magnetic recovery properties.

[0005] While uranium brings sustainable development benefits to the nuclear industry, it should also be noted that heavy metal uranium is also a radioactive and chemically toxic environmental pollutant. Therefore, incorporating materials with a specific fluorescent response to uranyl ions into micro-nano adsorbents could enable the integration of uranium extraction and detection. Summary of the Invention

[0006] In response to the above-mentioned deficiencies or improvements in the prior art, the present invention aims to provide magnetic hydrogel microspheres that combine uranium extraction and detection functions, and a method for preparing the same. By improving the components of the magnetic hydrogel microspheres and the corresponding preparation method, the resulting magnetic hydrogel microspheres can be used as adsorbents for uranium extraction from seawater, effectively addressing the shortcomings of the prior art. Furthermore, under the control of an external magnetic field, the magnetic hydrogel microspheres can freely move in a liquid medium, allowing for magnetic recovery. The magnetic hydrogel microspheres of the present invention possess excellent uranium adsorption properties, enabling simultaneous uranium extraction and detection, and possessing significant significance and practical value.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for preparing magnetic hydrogel microspheres having both uranium extraction and detection functions is provided, characterized in that the method comprises the following steps:

[0008] (1) Using a photopolymerizable monomer containing at least one of a hydroxyl group, a carboxyl group, an amino group, and an amide group as a raw material, adding the photopolymerizable monomer, a photoinitiator, and a crosslinking agent into deionized water, and mixing them uniformly to obtain a prepolymer solution;

[0009] (2) uniformly mixing the prepolymer obtained in step (1), the magnetic material, the metal organic framework material and deionized water to obtain an aqueous solution; wherein the metal organic framework material is any one of ZIF-8, ZIF-67, ZIF-90 and MOF-5;

[0010] (3) adding an emulsifier to the oil phase solvent and mixing uniformly to obtain an oil phase portion; then, uniformly mixing the aqueous phase solution obtained in step (2) with the oil phase portion at a volume ratio of 0.5:(20-40) to obtain a water-in-oil emulsion;

[0011] (4) The water-in-oil emulsion obtained in step (3) is heated to 50 mW / cm 2 The magnetic hydrogel microspheres are irradiated with ultraviolet light for 4-15 minutes to fully gelate the microspheres; and then washed.

[0012] As a further preferred embodiment of the present invention, in step (1), the photopolymerizable monomer is any one or more of acrylic acid, acrylamide, methacrylic acid, and methyl acrylate; and the mass ratio of the photopolymerizable monomer to the deionized water is (1-5):5.

[0013] As a further preferred embodiment of the present invention, in the step (2), the volume ratio of the prepolymer solution to the deionized water is (1-4):1.

[0014] As a further preferred embodiment of the present invention, in step (1), the photoinitiator is any one of 2,2'-azobisisobutylamidine dihydrochloride, 2-hydroxy-2-methylpropiophenone, 1-hydroxy-cyclohexyl-phenyl ketone, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone; the mass ratio of the photoinitiator to the photopolymerizable monomer is (0.5-5):15;

[0015] The crosslinking agent is any one of N-N'-methylenebis(acrylamide), divinylbenzene, and diisocyanate; and the mass ratio of the crosslinking agent to the photopolymerizable monomer is (1-10):100.

[0016] As a further preferred embodiment of the present invention, in step (2), the magnetic material is ferroferric oxide, ferrous oxide, chromium dioxide, rubidium iron boron, cobalt trioxide, Fe 12 O 19 Any one of Sr; the ratio of the mass of the magnetic material to the volume of the deionized water is (0.1-0.4) g: 1 mL;

[0017] The ratio of the mass of the metal organic framework material to the volume of the deionized water is (0.1-0.4) g:1 mL.

[0018] As a further preferred embodiment of the present invention, in step (3), the emulsifier is any one or more of Tween 80, Span 80, Span 85, L64, and M-2070; the oil phase solvent is any one of liquid paraffin, soybean oil, and olive oil;

[0019] The mass ratio of the emulsifier to the volume ratio of the oil phase solvent is (0.2-1) g:30 mL.

[0020] As a further preferred embodiment of the present invention, in step (1), the mixing is specifically carried out by ultrasonic mixing or mechanical stirring mixing;

[0021] In the step (2), the mixing is specifically carried out by ultrasonic mixing;

[0022] In the step (3), the mixing is performed by mechanical stirring; the speed of the mechanical stirring used in any mixing is 200-800 rpm, and the stirring time is 5-30 min;

[0023] The washing is specifically performed by centrifugation with cyclohexane and ethanol for multiple times, and the supernatant is removed.

[0024] According to another aspect of the present invention, the present invention provides magnetic hydrogel microspheres prepared by the above preparation method.

[0025] According to another aspect of the present invention, the present invention provides the use of the magnetic hydrogel microspheres in extracting uranium from seawater or detecting uranium in a solution by fluorescence quenching;

[0026] Preferably, the application further achieves controllable movement or recovery of the magnetic hydrogel microspheres by applying an external magnetic field.

[0027] The above technical solution conceived by the present invention, compared with the prior art, the magnetic hydrogel microspheres of the present invention, which have both uranium extraction and detection functions, use a compound containing at least a hydroxyl group, a carboxyl group, an amino group, or an amide group as a photopolymerizable monomer, and introduce a specific type of metal-organic framework material (i.e., ZIF-8, ZIF-67, ZIF-90, or MOF-5). The hydrogel microspheres obtained by the present invention have both specific fluorescence responsiveness to uranyl ions and excellent adsorption capacity for uranium, thus having both adsorption and detection functions for uranyl ions. In addition, the magnetic hydrogel microspheres can also be controlled to move under magnetic field control, accelerating the adsorption rate, while also facilitating magnetic recovery after adsorption is completed.

[0028] The photopolymerizable monomers of the present invention contain abundant hydroxyl, carboxyl, amino or amide groups, so that the adsorbent obtained by the present invention exhibits excellent adsorption capacity for uranium and has a high adsorption rate; the introduction of the metal organic framework material with high porosity can promote the entry of uranyl ions into the interior of the adsorbent, increasing the utilization efficiency of the adsorption sites; the synergistic effect of the metal organic framework material and the functional groups on the photopolymerizable monomer helps to increase the adsorption amount. In addition, the introduction of the magnetic material can not only achieve magnetic recovery after the adsorption is completed, but also can be controlled to move under the control of the magnetic field to accelerate the adsorption. Therefore, the magnetic hydrogel microspheres with uranium extraction and detection functions obtained by the present invention can be used as adsorbents for uranium extraction from seawater, and can also detect whether the test solution contains uranium by fluorescence quenching, and realize visual detection of uranyl ions in the system by changes in fluorescence intensity (further, the speed of the fluorescence quenching process can also reflect the relative high and low uranium concentration in the solution). In addition, the pre-enrichment of the magnetic hydrogel microspheres in the process of adsorbing uranyl ions in the present invention helps to improve the detection ability of the magnetic hydrogel microspheres and optimize the detection limit.

[0029] The magnetic multifunctional micro-nano adsorbent obtained by the present invention integrates detection, adsorption and recovery, can improve the adsorption rate and adsorption amount of uranyl ions, and can simultaneously realize uranium extraction and detection, as well as magnetically controlled movement and magnetic recovery, which is of great significance and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The SEM image and particle size distribution curve of the magnetic hydrogel microspheres prepared in Example 1; wherein, Figure 1 (A) is the SEM image. Figure 1 (B) in the figure is the particle size distribution curve.

[0031] Figure 2 Comparison of infrared spectra of the magnetic hydrogel microspheres prepared in Example 1 before and after uranium adsorption.

[0032] Figure 3 This is an aqueous optical image of the magnetic hydrogel microspheres prepared in Example 2.

[0033] Figure 4 This is a comparison chart of the saturated adsorption capacity of the magnetic hydrogel microspheres prepared in Example 2 in uranium solutions with different pH values.

[0034] Figure 5 This is an SEM image of the magnetic hydrogel microspheres prepared in Example 3 after adsorbing uranium.

[0035] Figure 6 The hysteresis loop and adsorption kinetic curve of the magnetic hydrogel microspheres prepared in Example 4; wherein, Figure 6(A) is the hysteresis loop and the actual photo of the prepared magnetic hydrogel microspheres being recovered by a magnet. Figure 6 (B) in the figure is the adsorption kinetics curve.

[0036] Figure 7 This is the motion trajectory of the magnetic hydrogel microspheres prepared in Example 5 under the control of the magnetic field.

[0037] Figure 8 This is a curve showing the change in fluorescence intensity of the magnetic hydrogel microspheres prepared in Example 5 over time in uranium solutions of different concentrations.

[0038] Figure 9 This is a comparison of the XPS full spectra of the magnetic hydrogel microspheres prepared in Example 6 before and after uranium adsorption.

[0039] Figure 10 Comparison of the adsorption capacity of the magnetic hydrogel microspheres prepared in Example 2 and Comparative Example 3. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0041] It should be noted in advance that: 1) Motion control under an external magnetic field is achieved by a three-dimensional Helmholtz coil. The device consists of three sets of coils and an imaging system. The principle is to generate a three-phase current through a programmable AC power supply. The current passes through the power amplifier and then enters the three sets of coils to generate a uniform / rotating / oscillating magnetic field. In the following embodiments, a rotating magnetic field in the xz direction or yz direction is applied, and the magnetic hydrogel microspheres roll forward along the x or y direction accordingly. 2) The uranium solutions of different concentrations used in the uranium adsorption test in the following embodiments are all obtained by diluting the 1000ppm uranium standard stock solution. Preparation method of 1000ppm uranium standard stock solution: Accurately weigh 210.95mg of uranyl nitrate hexahydrate into a 100mL reagent bottle, then add 2mL nitric acid and 98mL ultrapure water, and stir magnetically until completely dissolved to obtain a uranium standard stock solution with a concentration of 1000ppm, set aside. 3) Adsorption amount determination method: 60μL of the solution to be tested, 60μL of a solution with a concentration of 0.1mol·L -1 HCl solution, 120 μL of 500 mg·L -1 The arsenazo solution was mixed evenly with 360 μL ultrapure water and then transferred to a cuvette. The absorbance of the mixed solution at a wavelength of 652 nm was measured using a UV-visible spectrophotometer, and the adsorption amount of the adsorbent was calculated according to formula (1).

[0042]

[0043] Where Q is the adsorption amount (mg / g); C0 is the initial concentration of U(VI) in the uranium solution (mg / L); C is the concentration of U(VI) in the solution after adsorption (mg / L); V is the volume of the uranium solution (L); and m is the mass of the magnetic hydrogel microsphere uranium adsorbent (g).

[0044] Example 1

[0045] A method for preparing magnetic hydrogel microspheres with both uranium extraction and detection functions comprises the following steps:

[0046] (1) Preparation of prepolymer solution:

[0047] Dissolve 1.0 g of acrylamide in 2.0 g of deionized water (the mass ratio of photopolymerizable monomer to deionized water is 5:10), add 0.02 g of divinylbenzene as a crosslinker and 0.08 g of 2,2'-azobisisobutylamidine dihydrochloride as a photoinitiator, and stir well to obtain a prepolymer solution; wrap it with aluminum foil (the same below);

[0048] (2) Preparation of aqueous solution:

[0049] 0.3 mL of the prepolymer solution of step (1), 40 mg of chromium dioxide, 80 mg of ZIF-67, and 0.2 mL of deionized water were added to a 250 mL beaker and ultrasonically mixed to obtain an aqueous solution;

[0050] (3) Preparation of water-in-oil emulsion:

[0051] Add 30 mL of liquid paraffin to a 250 mL beaker, then add 0.2 g of Span 80 and stir evenly to fully disperse the Span 80 in the liquid paraffin to obtain an oil phase. Slowly drip the aqueous solution from step (2) into the oil phase and stir at 800 rpm for 5 minutes to obtain a water-in-oil emulsion.

[0052] (4) UV curing:

[0053] Take a certain volume of the water-in-oil emulsion in step (3) in a watch glass and measure it under an intensity of 25mW / cm 2 The solution was irradiated with UV light for 4 minutes to fully solidify the gel. The solution was then washed three times with cyclohexane and ethanol by centrifugation to remove the oil phase, yielding magnetic hydrogel microspheres with both uranium extraction and detection capabilities.

[0054] Figure 1 The SEM images and particle size distribution curves of the prepared magnetic hydrogel microspheres are shown in Figure 2. Figure 1As shown in (A), the prepared sample is a spherical shape with regular shape, which proves that the hydrogel microspheres were successfully synthesized by the microemulsion method; Figure 1 As shown in (B), the size of the microspheres is mostly distributed in the range of 2-4 μm. The prepared magnetic hydrogel microspheres were placed in a high concentration uranium solution for a certain period of time, and then recovered by a magnet for infrared spectroscopy characterization. Figure 2 The infrared spectra of the prepared magnetic hydrogel microspheres before and after uranium adsorption are compared. It can be seen from the figure that after uranium adsorption, the infrared spectra at 920 cm -1 There is a strong absorption peak of O=U=O at , indicating that uranium is successfully adsorbed on the sample.

[0055] Example 2

[0056] A method for preparing magnetic hydrogel microspheres with both uranium extraction and detection functions comprises the following steps:

[0057] (1) Preparation of prepolymer solution:

[0058] Dissolve 0.6g acrylamide and 0.6g acrylic acid in 1.2g deionized water (the mass ratio of photopolymerizable monomer to deionized water is 1:1), add 0.015g N-N'-methylenebis(acrylamide) as a crosslinker and 0.04g 2-hydroxy-2-methylpropiophenone as a photoinitiator, stir well, and obtain a prepolymer solution.

[0059] (2) Preparation of aqueous solution:

[0060] 0.25 mL of the prepolymer solution of step (1), 25 mg of ferrosoferric oxide, 60 mg of ZIF-8, and 0.25 mL of deionized water were added to a 250 mL beaker and mixed uniformly by ultrasonication to obtain an aqueous solution;

[0061] (3) Preparation of water-in-oil emulsion:

[0062] Add 40 mL of olive oil to a 250 mL beaker, then add 0.5 g of Tween 80 and stir evenly to fully disperse the Tween 80 in the olive oil to obtain an oil phase. Slowly drip the aqueous phase solution from step (2) into the oil phase and stir at 600 rpm for 12 minutes to obtain a water-in-oil emulsion.

[0063] (4) UV curing:

[0064] Take a certain volume of the water-in-oil emulsion in step (3) in a watch glass and measure it under an intensity of 10mW / cm 2 The solution was irradiated with UV light for 12 minutes to fully solidify the gel. The solution was then washed three times with cyclohexane and ethanol respectively by centrifugation to remove the oil phase, thereby obtaining magnetic hydrogel microspheres with both uranium extraction and detection functions.

[0065] This example investigates the adsorption performance of magnetic hydrogel microspheres prepared under pH conditions of 1.5-7.5 for U(VI). Uranium adsorption test method: Take a certain amount of 1000ppm uranium standard stock solution and dilute it to 40ppm with water. Take 15mL and adjust the pH of the uranium solution to 1.5, 3.0, 4.5, 6.0, and 7.5 with Na2CO3 / HCl; then add 75μL of 10mg·L -1 The adsorbent was added to the above solution (the mass ratio of the adsorbent to the volume of the uranium solution was 1 mg: 20 mL) and treated in a rotating magnetic field environment with a magnetic field strength of 100 Gs, a frequency of 6 Hz, and an xz direction for 50 min; then the solution was filtered through a micron-sized aqueous phase filter head to remove the adsorbed solution, and the concentration of U(VI) in the filtered solution was measured, and the adsorption amount was calculated using formula (1). Figure 3 This is the aqueous optical image of the prepared magnetic hydrogel microspheres. It can be seen from the image that the sample is a regular sphere with a size at the micron level, proving that the hydrogel microspheres were successfully synthesized through the microemulsion method. Figure 4 Comparison of the saturated adsorption capacity of the prepared magnetic hydrogel microspheres in uranium solutions with different pH values. The figure shows that the sample has the best adsorption when the pH value of the uranium solution is 4.5, and the adsorption capacity can reach 603.62 mg·g -1 .

[0066] Example 3

[0067] A method for preparing magnetic hydrogel microspheres with both uranium extraction and detection functions comprises the following steps:

[0068] (1) Preparation of prepolymer solution:

[0069] 0.7 g acrylamide and 0.82 g methacrylic acid were dissolved in 2.5 g deionized water (the mass ratio of photopolymerizable monomer to deionized water was 6:10), 0.016 g N-N'-methylenebis(acrylamide) as a crosslinker and 0.2 g 1-hydroxy-cyclohexyl-phenyl ketone as a photoinitiator were added, and stirred uniformly to obtain a prepolymer solution;

[0070] (2) Preparation of aqueous solution:

[0071] 0.4 mL of the prepolymer solution from step (1), 10 mg of Fe 12 O 19 Sr, 20 mg ZIF-90, and 0.1 mL deionized water were added to a 250 mL beaker and ultrasonically mixed to obtain an aqueous solution;

[0072] (3) Preparation of water-in-oil emulsion:

[0073] 35 mL of soybean oil was added to a 250 mL beaker. 0.3 g of Span 80 and 0.3 g of L64 were added and stirred until Span 80 and L64 were fully dispersed in the soybean oil to obtain an oil phase. The aqueous phase solution from step (2) was slowly added dropwise to the oil phase and stirred at 200 rpm for 30 min to obtain a water-in-oil emulsion.

[0074] (4) UV curing:

[0075] Take a certain volume of the water-in-oil emulsion in step (3) in a watch glass and measure it under an intensity of 10mW / cm 2 The solution was irradiated with UV light for 15 minutes to fully solidify the gel. The solution was then washed three times with cyclohexane and ethanol respectively by centrifugation to remove the oil phase, thereby obtaining magnetic hydrogel microspheres with both uranium extraction and detection functions.

[0076] The prepared magnetic hydrogel microspheres were added to a high concentration uranium solution for a certain period of time, and then recovered using a magnet for SEM characterization. Figure 5 This is an SEM image of the magnetic hydrogel microspheres prepared in Example 3 after uranium adsorption. The image shows that the uranium is evenly dispersed, proving that the uranium is successfully adsorbed on the sample.

[0077] Example 4

[0078] A method for preparing magnetic hydrogel microspheres with both uranium extraction and detection functions comprises the following steps:

[0079] (1) Preparation of prepolymer solution:

[0080] 0.6 g of acrylic acid was dissolved in 3.0 g of deionized water (the mass ratio of photopolymerizable monomer to deionized water was 1:5), 0.06 g of diisocyanate was added as a crosslinking agent, and 0.08 g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone was added as a photoinitiator, and stirred to obtain a prepolymer solution;

[0081] (2) Preparation of aqueous solution:

[0082] 0.2 mL of the prepolymer solution of step (1), 40 mg of rubidium iron boron, 30 mg of MOF-5, and 0.3 mL of deionized water were added to a 250 mL beaker and ultrasonically mixed to obtain an aqueous solution;

[0083] (3) Preparation of water-in-oil emulsion:

[0084] Add 20 mL of liquid paraffin to a 250 mL beaker, then add 0.2 g of Span 80 and 0.3 g of Tween 80. Stir evenly to fully disperse Span 80 and Tween 80 in the liquid paraffin to obtain an oil phase. Slowly dropwise add the aqueous phase solution from step (2) above into the oil phase and stir at 500 rpm for 18 minutes to obtain a water-in-oil emulsion.

[0085] (4) UV curing:

[0086] Take a certain volume of the water-in-oil emulsion in step (3) in a watch glass and measure it under the intensity of 5mW / cm 2 The solution was irradiated with UV light for 10 minutes to fully solidify the gel. The solution was washed three times with cyclohexane and ethanol respectively by centrifugation to remove the oil phase, thus obtaining magnetic hydrogel microspheres with both uranium extraction and detection functions.

[0087] This example explores the adsorption kinetics of the prepared magnetic hydrogel microspheres. Uranium adsorption test method: Take a certain amount of 1000ppm uranium standard stock solution and dilute it to 40ppm with water. Take 15mL and adjust the pH of the uranium solution to 4.5 with Na2CO3 / HCl; then add 75μL of 10mg·L -1 The adsorbent was placed in the above solution (the mass ratio of the adsorbent to the volume of the uranium solution was 1 mg: 20 mL) and treated in a rotating magnetic field environment with a magnetic field intensity of 100 Gs, a frequency of 6 Hz, and xz directions for 50 min. Samples were taken at certain time intervals to measure the absorbance at the corresponding time, and then the adsorption amount was calculated using formula (1).

[0088] Figure 6 Magnetic hysteresis loop and adsorption kinetic curve of the prepared magnetic hydrogel microspheres. Figure 6 As shown in (A), the hysteresis curve of the magnetic hydrogel microsphere sample is symmetrical, and the saturation magnetization value is 2.04emu·g -1 , the coercive force is zero, proving the superparamagnetism of the sample, which provides support for the controllable start-stop magnetic control of hydrogel microspheres under magnetic field; Figure 6 As shown in (B), the magnetic hydrogel microspheres can reach adsorption equilibrium in 20 minutes, and the adsorption rate is fast.

[0089] Example 5

[0090] A method for preparing magnetic hydrogel microspheres with both uranium extraction and detection functions comprises the following steps:

[0091] (1) Preparation of prepolymer solution:

[0092] 0.65 g of acrylic acid and 1 g of methyl methacrylate were dissolved in 2.35 g of deionized water (the mass ratio of photopolymerizable monomer to deionized water was 7:10), 0.0165 g of divinylbenzene as a crosslinking agent and 0.15 g of 1-hydroxy-cyclohexyl-phenyl ketone as a photoinitiator were added, and stirred uniformly to obtain a prepolymer solution;

[0093] (2) Preparation of aqueous solution:

[0094] 0.35 mL of the prepolymer solution of step (1), 25 mg of cobalt tetroxide, 25 mg of ZIF-8, and 0.15 mL of deionized water were added to a 250 mL beaker and ultrasonically mixed to obtain an aqueous solution;

[0095] (3) Preparation of water-in-oil emulsion:

[0096] Add 45 mL of soybean oil to a 250 mL beaker, then add 1.5 g of Tween 80 and stir evenly to fully disperse the Tween 80 in the soybean oil to obtain an oil phase. Slowly drop the aqueous phase solution from step (2) into the oil phase and stir at 700 rpm for 12 minutes to obtain a water-in-oil emulsion.

[0097] (4) UV curing:

[0098] Take a certain volume of the water-in-oil emulsion in step (3) in a watch glass and measure it under an intensity of 40mW / cm 2 The solution was irradiated with UV light for 8 minutes to fully solidify the gel. The solution was then washed three times with cyclohexane and ethanol respectively by centrifugation to remove the oil phase, thereby obtaining magnetic hydrogel microspheres with both uranium extraction and detection functions.

[0099] Figure 7 This figure shows the motion trajectory of the prepared magnetic hydrogel microspheres under magnetic field control. In this example, a rotating magnetic field in the xz or yz direction is applied. The specific conditions are as follows: the magnetic field strength is 140 Gs, the frequency is 10 Hz, and the external magnetic field in the xz direction is applied from 0s to 55s; the external magnetic field in the yz direction is applied from 56s to 92s; the external magnetic field in the xz direction is applied from 93s to 114s; and the external magnetic field in the yz direction is applied from 115s to 125s. As shown in the figure, under the control of the magnetic field, the sample can move along the expected trajectory, indicating that the movement of the microspheres can be precisely controlled by applying a magnetic field. Figure 8 The curve of the fluorescence intensity of the prepared magnetic hydrogel microspheres changing with time in uranium solutions of different concentrations is shown in the figure. As shown in the figure, the fluorescence intensity of the sample gradually decreases with the extension of the contact time with the uranium solution, proving that the microspheres can realize fluorescence detection of low-concentration uranium solutions.

[0100] Example 6

[0101] A method for preparing magnetic hydrogel microspheres with both uranium extraction and detection functions comprises the following steps:

[0102] (1) Preparation of prepolymer solution:

[0103] Dissolve 1.2 g of methyl methacrylate in 3 g of deionized water (the mass ratio of photopolymerizable monomer to deionized water is 4:10), add 0.05 g of diisocyanate as a crosslinking agent and 0.4 g of 2-hydroxy-2-methylpropiophenone as a photoinitiator, and stir well to obtain a prepolymer solution;

[0104] (2) Preparation of aqueous solution:

[0105] 0.15 mL of the prepolymer solution of step (1), 40 mg of ferric oxide, 40 mg of ZIF-90, and 0.35 mL of deionized water were added to a 250 mL beaker and ultrasonically mixed to obtain an aqueous solution;

[0106] (3) Preparation of water-in-oil emulsion:

[0107] Add 25 mL of olive oil to a 250 mL beaker, then add 0.6 g of M-2070 and stir evenly to fully disperse the M-2070 in the olive oil to obtain an oil phase. Slowly drip the aqueous phase solution from step (2) into the oil phase and stir at 400 rpm for 20 minutes to obtain a water-in-oil emulsion.

[0108] (4) UV curing:

[0109] Take a certain volume of the water-in-oil emulsion in step (3) in a watch glass and measure it under an intensity of 50mW / cm 2 The gel was then irradiated with UV light for 6 minutes to fully solidify. The hydrogel was then washed three times with cyclohexane and then ethanol, respectively, to remove the oil phase, yielding magnetic hydrogel microspheres capable of both uranium extraction and detection.

[0110] The prepared magnetic hydrogel microspheres were added to a high concentration uranium solution for a certain period of time, and then recovered by a magnet for XPS characterization. Figure 9 The XPS full spectrum of the prepared magnetic hydrogel microspheres before and after uranium adsorption is compared. It can be seen from the figure that the sample has a strong U 4f peak, indicating that uranium was successfully adsorbed on the sample.

[0111] Comparative Example 1

[0112] The volume of liquid paraffin in step (3) of Example 1 was adjusted to 15 mL; the rest was kept consistent with Example 1. The final sample was stuck together and could not be dispersed by ultrasound.

[0113] Comparative Example 2

[0114] The UV lamp irradiation time in step (4) of Example 2 was adjusted to 2 minutes; the other conditions remained the same as in Example 2, and the resulting sample was extremely small and irregular in shape.

[0115] Comparative Example 3

[0116] The metal organic framework material (ZIF-8) is not added in step (2) of Example 2; the rest remains the same as Example 2.

[0117] This comparative example explores the effect of the introduction of metal organic framework materials on the adsorption properties of the prepared magnetic hydrogel microspheres. The uranium adsorption method of Example 2 is the same as that of Comparative Example 3. Uranium adsorption test method: Take a certain amount of 1000ppm uranium standard stock solution and dilute it to 40ppm with water. Take 15mL and adjust the pH of the uranium solution to 4.5 with Na2CO3 / HCl; then add 75μL of 10mg·L -1 The adsorbent is placed in the above solution (the volume ratio of the adsorbent mass to the uranium solution is 1 mg: 20 mL), and treated in a rotating magnetic field environment with a magnetic field strength of 100 Gs, a frequency of 6 Hz, and an xz direction for 50 minutes; then the solution is filtered through a micron-sized aqueous phase filter head to filter the adsorbed solution, and the concentration of U (VI) in the filtered solution is measured, and the adsorption amount is calculated by formula (1). The mass of each component in Example 2 is calculated to be: polymer (167 mg), ZIF-8 (60 mg), and it is estimated that the mass proportion of the polymer is 0.74, and the mass proportion of ZIF-8 is 0.26. The adsorption amount of the comparative example 3 sample without the ZIF-8 component is 543 mg·g -1 , theoretically, the adsorption capacity of the polymer in Example 2 is 301.37 mg / g microspheres; the adsorption capacity of ZIF-8 is 184.7 mg·g -1 , then theoretically the adsorption capacity of the ZIF-8 component in Example 2 is 36.02 mg / g microspheres. The sum of the two is 337.39 mg·g -1 , while the actual sample adsorption capacity is 603.61 mg·g -1 , which is much higher than the sum of the adsorption capacity of the three components. The synergistic effect between the metal organic framework material and the photopolymerization monomer can improve the adsorption performance of the adsorbent. Figure 10 The comparison of the adsorption amount of single-component and multi-component samples is intuitively displayed.

[0118] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Application of magnetic hydrogel microspheres with both uranium extraction and detection functions in extracting uranium from seawater and detecting uranium in solution by fluorescence quenching, characterized in that: The method for preparing the magnetic hydrogel microspheres having both uranium extraction and detection functions comprises the following steps: (1) Using a photopolymerizable monomer containing at least one of a hydroxyl group, a carboxyl group, an amino group, and an amide group as a raw material, adding the photopolymerizable monomer, a photoinitiator, and a crosslinking agent into deionized water, and mixing them uniformly to obtain a prepolymer solution; (2) uniformly mixing the prepolymer obtained in step (1), the magnetic material, the metal organic framework material and deionized water to obtain an aqueous solution; wherein the metal organic framework material is any one of ZIF-8, ZIF-67, ZIF-90 and MOF-5; (3) adding an emulsifier to the oil phase solvent and mixing uniformly to obtain an oil phase portion; then, uniformly mixing the aqueous phase solution obtained in step (2) with the oil phase portion at a volume ratio of 0.5:(20-40) to obtain a water-in-oil emulsion; (4) The water-in-oil emulsion obtained in step (3) is heated to 50 mW / cm 2 The magnetic hydrogel microspheres are irradiated with ultraviolet light for 4-15 minutes to fully gelate the microspheres; and then washed to obtain magnetic hydrogel microspheres. The magnetic hydrogel microspheres have both specific fluorescence responsiveness to uranyl ions and adsorption capacity for uranium.

2. The use according to claim 1, characterized in that In the step (1), the photopolymerizable monomer is any one or more of acrylic acid, acrylamide, methacrylic acid, and methyl acrylate; and the mass ratio of the photopolymerizable monomer to the deionized water is (1-5):

5.

3. The use according to claim 1, characterized in that In the step (2), the volume ratio of the prepolymer solution to the deionized water is (1-4):

1.

4. The use according to claim 1, characterized in that In the step (1), the photoinitiator is any one of 2,2'-azobisisobutylamidine dihydrochloride, 2-hydroxy-2-methylpropiophenone, 1-hydroxy-cyclohexyl-phenyl ketone, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone; the mass ratio of the photoinitiator to the photopolymerizable monomer is (0.5-5):15; The crosslinking agent is any one of N-N'-methylenebis(acrylamide), divinylbenzene, and diisocyanate; and the mass ratio of the crosslinking agent to the photopolymerizable monomer is (1-10):

100.

5. The use according to claim 1, characterized in that In the step (2), the magnetic material is ferroferric oxide, ferrous oxide, chromium dioxide, rubidium iron boron, cobalt tetraoxide, Fe 12 O 19 Any one of Sr; the ratio of the mass of the magnetic material to the volume of the deionized water is (0.1-0.4) g: 1 mL; The ratio of the mass of the metal organic framework material to the volume of the deionized water is (0.1-0.4) g:1 mL.

6. The use according to claim 1, characterized in that In the step (3), the emulsifier is any one or more of Tween 80, Span 80, Span 85, L64, and M-2070; the oil phase solvent is any one of liquid paraffin, soybean oil, and olive oil; The mass ratio of the emulsifier to the volume ratio of the oil phase solvent is (0.2-1) g:30 mL.

7. The use according to claim 1, characterized in that In the step (1), the mixing is specifically carried out by ultrasonic mixing or mechanical stirring mixing; In the step (2), the mixing is specifically carried out by ultrasonic mixing; In the step (3), the mixing is performed by mechanical stirring; the speed of the mechanical stirring used in any mixing is 200-800 rpm, and the stirring time is 5-30 min; The washing is specifically performed by centrifugation with cyclohexane and ethanol for multiple times, and the supernatant is removed.

8. The use according to claim 1, characterized in that The application also achieves controllable movement or recovery of magnetic hydrogel microspheres by applying an external magnetic field.

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