Preparation method and application of nano composite material for removing uranium through photocatalysis under acidic uranium-containing wastewater system

Abstract

The invention discloses a preparation method of a nano composite material for removing uranium through photocatalysis under an acidic uranium-containing wastewater system. The preparation method comprises the following steps: preparing a CdS nano rod by using Cd (NO3) 2.4 H2O and NH2CSNH2; preparing a high-entropy alloy from ferric acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate and manganese acetylacetonate; and adding the CdS nanorod into water, carrying out ultrasonic dispersion to obtain a CdS solution for later use, adding a high-entropy alloy into water, carrying out ultrasonic dispersion to obtain a high-entropy alloy solution, then adding the alloy aqueous solution into the CdS solution, carrying out strong magnetic stirring, carrying out heat preservation for a period of time after stirring is completed, and then filtering, washing and drying to obtain the nano composite material. Uranium under the acidic condition (pH = 3-8) can be effectively removed; the technology is green and environment-friendly, and secondary pollution caused by chemical reagents is avoided; operation is simple, reaction devices are not complex, reaction conditions are mild, and control is easy; meanwhile, the photocatalyst can be recycled, the cost is reduced, and the photocatalyst can be combined with other treatment technologies to synergistically improve the treatment effect.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear wastewater purification or environmental radiochemistry, and particularly relates to a preparation method and application of a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system. Background Art

[0002] The development and utilization of nuclear energy is considered to be one of the main ways to solve the world energy crisis. At that time, a large amount of medium and low-level radioactive liquid waste / wastewater containing uranium will be generated every year due to the treatment of unloaded spent fuel. Uranium, as the main radionuclide in the radioactive "three wastes" generated during nuclear fuel production, nuclear power plant operation, and nuclear facility decommissioning, has a relatively long half-life and extremely high physical and chemical toxicity. It mainly exists in the form of dissolved hexavalent uranium (U(VI)) in the environment and is extremely easy to migrate to the biosphere along with surface water and groundwater, which may cause significant harm to the ecological environment and normal human life activities. Therefore, how to efficiently, safely, and low-costly treat radioactive wastewater containing uranium remains a difficult problem that needs to be faced urgently in the sustainable development of nuclear energy.

[0003] Since U(VI) ions are generally highly soluble and mobile, while U(IV) species, especially oxides / hydroxides, are relatively insoluble and relatively immobile, reducing U(VI) to U(IV) precipitation is another method for separating and recovering uranium from aqueous solutions. Since 1972, when Fujishima and Honda first used TiO 2 thin film as a working electrode to achieve photocatalytic water splitting, the semiconductor photocatalytic technology driven by solar energy has rapidly become a research hotspot in the fields of energy and environment. In recent years, semiconductor photocatalysis has been widely used in hydrogen production and carbon dioxide emission reduction. This technology is also applicable to the separation and recovery of uranium. During the photocatalytic process, the semiconductor catalyst is excited by a light source to generate electron-hole pairs, and the photoelectrons can reduce the highly soluble and mobile hexavalent uranium (U(VI)) into a relatively insoluble and relatively immobile tetravalent uranium (U(IV)) product, thereby achieving the reduction and fixation of uranium. However, the acidity of real uranium-containing wastewater is relatively strong, resulting in ineffective photocatalytic reduction and removal of uranium. Therefore, there is an urgent need for a material that can effectively achieve the photocatalytic reduction and removal of hexavalent uranium in acidic uranium-containing wastewater. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0005] The present invention provides a preparation method of a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system, including the following steps:

[0006] Step 1: Use Cd(NO 3 )2 ·4H 2 O and NH 2 CSNH 2 Prepare CdS nanorods;

[0007] Step 2: Prepare a high-entropy alloy (HEA) using iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate, and manganese acetylacetonate;

[0008] Step 3: Add the CdS nanorods to water and disperse them by ultrasonic treatment to obtain a CdS solution for standby. Add the high-entropy alloy to water and disperse it by ultrasonic treatment to obtain a high-entropy alloy solution. Then add the alloy aqueous solution to the CdS solution and perform strong magnetic stirring. After stirring and keeping warm for a period of time, filter, wash, and dry to obtain a nanocomposite, namely the HEA / CdS composite photocatalyst.

[0009] Preferably, Step 1 specifically includes: Dissolve Cd(NO 3 ) 2 ·4H 2 O and NH 2 CSNH 2 in ethylenediamine, stir evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave, heat it in an oven for a period of time, then cool it to room temperature, centrifuge to collect the precipitate in the mixed solution, wash, and dry to obtain CdS nanorods.

[0010] Preferably, Step 2 specifically includes: Add iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate, and manganese acetylacetonate to a mixed solution of acetone and ethanol respectively to obtain precursor solutions containing different metals. Add the prepared precursor solutions together to a steel autoclave lined with Teflon, seal the autoclave, and place it in an oven to heat for a period of time, then cool it to room temperature, centrifuge to collect the solid product, wash, and dry to obtain a high-entropy alloy.

[0011] Preferably, in Step 1, the molar ratio of Cd(NO 3 ) 2 ·4H 2 O, NH 2 CSNH 2 , ethylenediamine is 2-4:6-8:200-400, the heating temperature is 180-200°C, and the heating time is 12-28 h.

[0012] Preferably, in Step 1, the centrifugation speed is 6000-8000 rpm, the centrifugation time is 8-15 min. When washing the precipitate, wash it 3-6 times with distilled water and anhydrous ethanol respectively, and the drying temperature is 50-70°C, and the drying time is 5-12 h.

[0013] Preferably, in step 2, the molar ratio of iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate and manganese acetylacetonate is 1:1:1:1:1, the volume ratio of acetone to ethanol in the mixed solution of acetone and ethanol is 45-55:45-55, and the metal concentration of the precursor solution is 3×10 -3 ~6×10 -3 M / L.

[0014] Preferably, in step 2, the heating temperature is 200° C., the heating is for 24 hours, the centrifugal speed is 6000-8000 rpm, the centrifugation is for 8-15 minutes, and the drying temperature is 50-70° C., and the drying is for 5-12 hours.

[0015] Preferably, in step three, the mass ratio of CdS nanorods to water is 0.8-1.2:2500-3500, the mass ratio of high entropy alloy to water is 0.8-1.2:800-1200, and the volume ratio of CdS solution to high entropy solution is 90-110:3-20.

[0016] Preferably, in step three, the strong magnetic stirring speed is 10-30 Hz, the stirring time is 10-30 min, after the stirring is completed, the temperature is kept for 18-30 h, the drying temperature is 55-65° C., and the drying is performed for 8-20 h.

[0017] Preferably, when preparing CdS in step 1, Cd(NO 3 ) 2 ·4H 2 O mass 5~10wt% Co(NO 3 ) 2 6H 2 O, to prepare cobalt-doped CdS, and then in step 2, when preparing the high entropy alloy, additionally add cerium acetylacetonate in the same molar ratio to prepare the cerium-doped high entropy alloy.

[0018] The invention also provides an application of the nanocomposite material, wherein the nanocomposite material is used to remove hexavalent uranium from acidic uranium-containing wastewater with a pH value of 3-8.

[0019] The present invention at least has the following beneficial effects: the present invention can effectively remove uranium under acidic conditions (pH = 3 to 8); under acidic conditions, when the photocatalyst is irradiated with light whose energy is greater than its bandgap width, the electrons in the valence band will be excited to transition to the conduction band, thereby forming holes H in the valence band. + , forming photogenerated electrons e in the conduction band - , generating photogenerated carriers. Under acidic conditions, uranium is mainly in the form of hexavalent uranyl ions UO 2 2+ Hydrogen atom H . He Guangsheng Electronics- It can gradually reduce UO 2 2+ to tetravalent uranium U 4+ . Uranium U 4+ has a low solubility under acidic conditions and will precipitate or be adsorbed on the surface of the photocatalyst, thus achieving the purpose of removing uranium from the solution; the present invention also dopes Co in CdS, which can effectively transfer photogenerated electrons, reduce the recombination probability of photogenerated electron-hole pairs, thereby improving the photocatalytic activity of the composite photocatalyst and simultaneously slowing down the occurrence of photocorrosion and prolonging the service life of cadmium sulfide; and rare earth metal cerium is doped in the high-entropy alloy to enhance the corrosion resistance of the composite catalyst under acidic conditions. The technology of the present invention is green and environmentally friendly, only requiring light and a photocatalyst, avoiding secondary pollution caused by chemical reagents; it is easy to operate, the reaction device is not complex, the reaction conditions are mild and easy to control; at the same time, the photocatalyst can be recycled, reducing costs, and can also be used in combination with other treatment technologies to synergistically improve the treatment effect.

[0020] Other advantages, objectives and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a scanning electron microscope schematic diagram of the nanocomposite prepared in Example 1 of the present invention;

[0022] Figure 2 It is a scanning electron microscope schematic diagram of CdS nanorods in Example 1 of the present invention;

[0023] Figure 3 It is a physical picture of the HEA solution in Example 1 of the present invention;

[0024] Figure 4 It is a schematic diagram of the removal rate effect of hexavalent uranium under the condition of pH = 3 in Application Example 1 of the present invention;

[0025] Figure 5 It is a schematic diagram of the removal rate effect of hexavalent uranium under the condition of pH = 3 in Examples 4-5 of the present invention;

[0026] Figure 6 It is a graph of the removal rate of hexavalent uranium in the cyclic test in Application Example 1 of the present invention;

[0027] Figure 7 It is a graph of the removal rate of hexavalent uranium at different concentrations in Application Example 1 of the present invention;

[0028] Figure 8 It is a graph of the removal rate of hexavalent uranium at different pH values in Application Example 1 of the present invention;

[0029] Figure 9Schematic diagram of the removal effect of hexavalent uranium in Comparative Examples 3-4 of the present invention under the condition of pH = 3. Detailed implementation manners

[0030] The following further describes the present invention in detail with reference to the accompanying drawings, so that those skilled in the art can implement it according to the description in the specification.

[0031] It should be understood that the terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0032] Example 1

[0033] A preparation method of a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system, comprising the following steps:

[0034] Step 1: Dissolve 0.925 g of Cd(NO 3 ) 2 ·4H 2 O and 0.563 g of NH 2 CSNH 2 in 20 mL of ethylenediamine, stir for 30 min. After stirring evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave, and heat it in an oven at 200 °C for 24 hours, then cool to room temperature. Centrifuge at a rate of 7000 rpm for 10 min, collect the precipitate in the mixed solution after centrifugation, wash it 5 times with distilled water and anhydrous ethanol respectively, and then dry it at 60 °C for 8 h to obtain CdS nanorods (the scanning electron micrograph is as shown in Figure 2 );

[0035] Step 2: Add 176.5 mg of iron acetylacetonate, 178 mg of cobalt acetylacetonate, 128.35 mg of nickel acetylacetonate, 130.78 mg of copper acetylacetonate and 175.97 mg of manganese acetylacetonate into a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 6 mL of each of the prepared precursor solutions into a steel autoclave lined with Teflon, seal the autoclave and place it in an oven to heat at 200 °C for 24 hours, then cool to room temperature, centrifuge at 7000 rpm for 10 min, collect the solid product after centrifugation, wash it 2 times with acetone, and dry it overnight at 60 °C in a vacuum drying oven to obtain a high-entropy alloy;

[0036] Step 3: Add 10 mg of CdS nanorods into 30 mL of water and disperse them by ultrasonic treatment to obtain a CdS solution for standby. Add 10 mg of the high-entropy alloy into 10 mL of water and disperse them by ultrasonic treatment to obtain a HEA solution (as shown in Figure 3As shown in the figure, 5.26 mL of the HEA solution was then added to 30 mL of the CdS solution, and strong magnetic stirring was carried out at 10 Hz for 20 min. After the stirring was completed, it was stored at room temperature for 24 h, then filtered, washed with deionized water, and dried in a vacuum oven at 60 °C for 12 h to obtain a nanocomposite, namely the HEA / CdS composite photocatalyst, denoted as 5-HEA / CdS.

[0037] Figure 1 It is a scanning electron microscope schematic diagram of the nanocomposite prepared in Example 1; it can be seen that compared with the CdS nanorods ( Figure 2 ) alloy nanoparticles are attached. It proves the successful preparation of the composite material.

[0038] Example 2

[0039] A preparation method of a nanocomposite for photocatalytic removal of uranium in an acidic uranium-containing wastewater system, comprising the following steps:

[0040] Step 1: Dissolve 0.925 g of Cd(NO 3 ) 2 ·4H 2 O and 0.563 g of NH 2 CSNH 2 in 20 mL of ethylenediamine, stir for 30 min. After stirring evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave and heat it in an oven at 200 °C for 24 h, then cool to room temperature. Centrifuge at a rate of 7000 rpm for 10 min, collect the precipitate in the mixed solution after centrifugation and wash it 5 times with distilled water and anhydrous ethanol respectively, and then dry it at 60 °C for 8 h to obtain CdS nanorods (whose scanning electron microscope image is as Figure 2 shown);

[0041] Step 2: Add 176.5 mg of iron acetylacetonate, 178 mg of cobalt acetylacetonate, 128.35 mg of nickel acetylacetonate, 130.78 mg of copper acetylacetonate, and 175.97 mg of manganese acetylacetonate to a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 6 mL of each of the prepared precursor solutions to a steel autoclave with a Teflon lining, seal the autoclave and place it in an oven to heat at 200 °C for 24 h, then cool to room temperature, centrifuge at 7000 rpm for 10 min, collect the solid product after centrifugation and wash it 2 times with acetone, and dry it overnight in a vacuum drying oven at 60 °C to obtain a high-entropy alloy;

[0042] Step 3: Add 10 mg of CdS nanorods to 30 mL of water and disperse them by ultrasonic treatment to obtain a CdS solution for standby. Add 10 mg of high-entropy alloy to 10 mL of water and disperse it by ultrasonic treatment to obtain an HEA solution. Then, add 1.01 mL of the HEA solution to 30 mL of the CdS solution and perform strong magnetic stirring at 10 Hz for 20 min. After the stirring is completed, store it at room temperature for 24 h, then filter, wash it with deionized water, and dry it in a vacuum oven at 60 °C for 12 h to obtain a nanocomposite, namely, an HEA / CdS composite photocatalyst, denoted as 1-HEA / CdS.

[0043] Example 3

[0044] A preparation method of a nanocomposite for photocatalytic removal of uranium in an acidic uranium-containing wastewater system, comprising the following steps:

[0045] Step 1: Dissolve 0.925 g of Cd(NO 3 ) 2 ·4H 2 O and 0.563 g of NH 2 CSNH 2 in 20 mL of ethylenediamine, stir for 30 min. After stirring evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave and heat it in an oven at 200 °C for 24 h, then cool it to room temperature. Centrifuge at a rate of 7000 rpm for 10 min, collect the precipitate in the mixed solution after centrifugation and wash it 5 times with distilled water and anhydrous ethanol respectively, and then dry it at 60 °C for 8 h to obtain CdS nanorods (the scanning electron micrograph is as shown in Figure 2 );

[0046] Step 2: Add 176.5 mg of iron acetylacetonate, 178 mg of cobalt acetylacetonate, 128.35 mg of nickel acetylacetonate, 130.78 mg of copper acetylacetonate, and 175.97 mg of manganese acetylacetonate to a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 6 mL of each of the prepared precursor solutions to a steel autoclave with a Teflon lining, seal the autoclave and place it in an oven to heat at 200 °C for 24 h, then cool it to room temperature, centrifuge at 7000 rpm for 10 min, collect the solid product after centrifugation and wash it 2 times with acetone, and dry it overnight in a vacuum drying oven at 60 °C to obtain a high-entropy alloy;

[0047] Step 3: Add 10 mg of CdS nanorods to 30 mL of water and disperse them by ultrasonic treatment to obtain a CdS solution for standby. Add 10 mg of high-entropy alloy to 10 mL of water and disperse it by ultrasonic treatment to obtain an HEA solution. Then, add 11.11 mL of the HEA solution to 30 mL of the CdS solution and perform strong magnetic stirring at 10 Hz for 20 min. After the stirring is completed, store it at room temperature for 24 h, then filter, wash it with deionized water, and dry it in a vacuum oven at 60 °C for 12 h to obtain a nanocomposite, namely the HEA / CdS composite photocatalyst, denoted as 10-HEA / CdS.

[0048] Example 4

[0049] A preparation method of a nanocomposite for photocatalytic removal of uranium in an acidic uranium-containing wastewater system, comprising the following steps:

[0050] Step 1: Dissolve 0.925 g of Cd(NO 3 ) 2 ·4H 2 O, 0.074 g of Co(NO 3 ) 2 ·6H 2 O, and 0.563 g of NH 2 CSNH 2 in 20 mL of ethylenediamine, stir for 30 min. After stirring evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave and heat it in an oven at 200 °C for 24 h, then cool it to room temperature. Centrifuge at a rate of 7000 rpm for 10 min. After centrifugation, collect the precipitate in the mixed solution and wash it 5 times with distilled water and anhydrous ethanol respectively, and then dry it at 60 °C for 8 h to obtain Co-doped CdS nanorods CdS / Co;

[0051] Step 2: Add 176.5 mg of iron acetylacetonate, 178 mg of cobalt acetylacetonate, 128.35 mg of nickel acetylacetonate, 130.78 mg of copper acetylacetonate, and 175.97 mg of manganese acetylacetonate to a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 6 mL of each of the prepared precursor solutions to a steel autoclave lined with Teflon. Seal the autoclave and place it in an oven to heat at 200 °C for 24 h, then cool it to room temperature. Centrifuge at 7000 rpm for 10 min. After centrifugation, collect the solid product and wash it 2 times with acetone, and dry it overnight in a vacuum drying oven at 60 °C to obtain the high-entropy alloy HEA;

[0052] Step 3: Add 10 mg of CdS / Co nanorods to 30 mL of water and disperse them by ultrasonic treatment to obtain a CdS / Co solution for standby. Add 10 mg of high-entropy alloy HEA to 10 mL of water and disperse it by ultrasonic treatment to obtain an HEA / Ce solution. Then add 5.26 mL of the HEA solution to 30 mL of the CdS / Co solution and perform strong magnetic stirring at 10 Hz for 20 min. After the stirring is completed, store it at room temperature for 24 h, then filter, wash it with deionized water, and dry it in a vacuum oven at 60 °C for 12 h to obtain a nanocomposite, that is, a composite photocatalyst, denoted as 5-HEA / CdS / Co.

[0053] Example 5

[0054] A preparation method of a nanocomposite for photocatalytic removal of uranium in an acidic uranium-containing wastewater system, comprising the following steps:

[0055] Step 1: Dissolve 0.925 g of Cd(NO 3 ) 2 ·4H 2 O, 0.074 g of Co(NO 3 ) 2 ·6H 2 O, and 0.563 g of NH 2 CSNH 2 in 20 mL of ethylenediamine, stir for 30 min. After stirring evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave and heat it in an oven at 200 °C for 24 h, then cool it to room temperature. Centrifuge at a rate of 7000 rpm for 10 min, collect the precipitate in the mixed solution after centrifugation, and wash it 5 times with distilled water and anhydrous ethanol respectively, and then dry it at 60 °C for 8 h to obtain Co-doped CdS nanorods CdS / Co;

[0056] Step 2: Add 176.5 mg of iron acetylacetonate, 178 mg of cobalt acetylacetonate, 128.35 mg of nickel acetylacetonate, 130.78 mg of copper acetylacetonate, 175.97 mg of manganese acetylacetonate, and 218.7 mg of cerium acetylacetonate to a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 6 mL of each of the prepared precursor solutions to a steel autoclave with a Teflon lining, seal the autoclave, and place it in an oven to heat at 200 °C for 24 h, then cool it to room temperature, centrifuge at 7000 rpm for 10 min, collect the solid product after centrifugation, wash it 2 times with acetone, and dry it overnight in a vacuum drying oven at 60 °C to obtain Ce-doped high-entropy alloy HEA / Ce;

[0057] Step 3: Add 10 mg of CdS / Co nanorods to 30 mL of water and disperse them by ultrasonic treatment to obtain a CdS / Co solution for standby. Add 10 mg of high-entropy alloy HEA / Ce to 10 mL of water and disperse them by ultrasonic treatment to obtain an HEA / Ce solution. Then, add 5.26 mL of the HEA / Ce solution to 30 mL of the CdS / Co solution and perform strong magnetic stirring at 10 Hz for 20 min. After the stirring is completed, store it at room temperature for 24 h, then filter, wash it with deionized water, and dry it in a vacuum oven at 60 °C for 12 h to obtain a nanocomposite, that is, a composite photocatalyst, denoted as 5-HEA / Ce / CdS / Co.

[0058] Comparative Example 1 (only prepare CdS)

[0059] Dissolve 0.925 g of Cd(NO 3 ) 2 ·4H 2 O and 0.563 g of NH 2 CSNH 2 in 20 mL of ethylenediamine, stir for 30 min. After stirring evenly, transfer the mixed solution to a polytetrafluoroethylene-lined autoclave and heat it in an oven at 200 °C for 24 h, then cool it to room temperature. Centrifuge at a rate of 7000 rpm for 10 min. After centrifugation, collect the precipitate in the mixed solution and wash it 5 times with distilled water and anhydrous ethanol respectively, and then dry it at 60 °C for 8 h to obtain CdS nanorods.

[0060] Comparative Example 2 (only prepare HEA)

[0061] Add iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate, and manganese acetylacetonate to a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 30 mL of the prepared precursor solution to a steel autoclave lined with Teflon. Seal the autoclave and place it in an oven to heat at 200 °C for 24 h, then cool it to room temperature. Centrifuge at 7000 rpm for 10 min. After centrifugation, collect the solid product and wash it 2 times with acetone, and dry it overnight in a vacuum drying oven at 60 °C to obtain a high-entropy alloy;

[0062] Application Example 1

[0063] The uranium adsorption performance of the HEA / CdS composite photocatalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was tested. The method was as follows: 2 ml of a U solution (250 ppm) was dropped into a 50 ml glass bottle using a pipette, and then 18 ml of pure water was added to make the concentration of the U solution 25 ppm. 10 mg of the nanocomposite material (HEA / CdS composite photocatalyst) prepared in Example 1 was added and stirred evenly with a stir bar to prepare a series of suspensions with the required initial uranium concentration; the pH was adjusted to 3 with trace amounts of NaOH and HCl. The solution with the adjusted pH was subjected to dark adsorption treatment and stirred in the dark for 60 min. Samples were taken every 30 min, 1 ml each time; after 60 min of dark adsorption, the light source was turned on and photocatalytic reduction was started, and samples were taken every 10 min, 1 ml each time. After taking samples six times, the instrument was turned off. The concentration of U(VI) was measured using a UV spectrophotometer.

[0064] Figure 4 It is a schematic diagram of the removal rate of hexavalent uranium in Examples 1 to 3 and Comparative Examples 1 to 2 under the condition of pH = 3. It can be seen that under acidic conditions (pH = 3), this nanocomposite material has a better photocatalytic reduction effect on uranium compared with CdS nanorods, and among them, the uranium removal rate of the 5-HEA / CdS nanocomposite material is the best.

[0065] The composite catalysts prepared in Examples 4 to 5 were used to test the uranium adsorption performance according to the method in Application Example 1. The results are as Figure 5 shown. It was found that in Example 4, due to the doping of Co in CdS on the basis of Example 1, the photogenerated electrons can be effectively transferred, the recombination probability of photogenerated electron-hole pairs can be reduced, thereby improving the photocatalytic activity of the composite photocatalyst, and at the same time slowing down the occurrence of photocorrosion and prolonging the service life of cadmium sulfide; in Example 5, on the basis of Example 1, while doping Co in CdS, rare earth metal cerium was also doped in the high-entropy alloy to improve the corrosion resistance of the composite catalyst under acidic conditions. Therefore, the composite catalyst in Example 5 not only has an improved efficiency of photocatalytic removal of hexavalent uranium, but also after being repeated many times under acidic conditions, the composite catalyst material is basically not corroded and still has a good photocatalytic effect.

[0066] The HEA / CdS composite photocatalyst prepared in Example 1 was used for cyclic adsorption testing under the same conditions as in Application Example 1. Figure 6 It is a graph of the removal rate of hexavalent uranium in the cyclic test. It can be seen that the HEA / CdS composite photocatalyst prepared in the present invention can be recycled at least 5 times under the condition that the use conditions remain unchanged and the reduction effect is ensured.

[0067] Uranium solutions U(VI) with different concentrations (1 - 100 ppm) were prepared, and the HEA / CdS composite photocatalyst prepared in Example 1 was used for uranium adsorption testing. Figure 7It is the removal rate graph of hexavalent uranium at different concentrations. It can be seen that the HEA / CdS composite photocatalyst prepared by the present invention has good removal effect on hexavalent uranium at different uranium concentrations.

[0068] Prepare hexavalent uranium solutions with pH values of 4, 5, 6, 7, and 8 respectively, and use the HEA / CdS composite photocatalyst of Example 1 to conduct uranium adsorption tests. Figure 8 It is the removal rate graph of hexavalent uranium at different pH values. It can be seen that under acidic conditions, the removal rate of hexavalent uranium remains stable, indicating that the material stability of the HEA / CdS composite photocatalyst prepared by the present invention is good.

[0069] Comparative Example 3

[0070] Step 1: Dissolve 2 g of tetrabutyl titanate (TBT) in 80 ml of alcohol, stir for half an hour, put the stirred solution into a 100 ml Teflon-lined autoclave, and heat it at 180 °C for 24 hours. After washing, centrifuge several times with ethanol, and place the obtained white sample in a drying oven at 60 °C for 24 hours. Finally, remove the dried powder sample and place it in a muffle furnace at a rate of 5 °C / min -1 and heat it to 470 °C and then heat for another 1 hour.

[0071] Step 2: Add 176.5 mg of iron acetylacetonate, 178 mg of cobalt acetylacetonate, 128.35 mg of nickel acetylacetonate, 130.78 mg of copper acetylacetonate, and 175.97 mg of manganese acetylacetonate into a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 6 mL of each of the prepared precursor solutions into a steel autoclave with a Teflon lining, seal the autoclave and place it in an oven to heat at 200 °C for 24 hours, then cool to room temperature, centrifuge at 7000 rpm for 10 min, collect the solid product after centrifugation, wash it twice with acetone, and dry it overnight at 60 °C in a vacuum drying oven to obtain a high-entropy alloy;

[0072] Step 3: Add 10 mg of TiO 2 to 30 mL of water and ultrasonically disperse it to obtain a TiO 2 solution for standby. Add 10 mg of the high-entropy alloy to 10 mL of water and ultrasonically disperse it to obtain a HEA solution. Then add 1.01 mL of the HEA solution to 30 mL of the TiO 2 solution and conduct strong magnetic stirring at 10 Hz for 20 min. After the stirring is completed, store it at room temperature for 24 h, then filter, wash it with deionized water, and dry it at 60 °C in a vacuum oven for 12 h to obtain a nanocomposite, namely the HEA / TiO 2 composite photocatalyst, denoted as 1-HEA / TiO 2。

[0073] Comparative Example 4

[0074] Step 1: Dissolve 2 g of tetrabutyl titanate (TBT) in 80 ml of alcohol, stir for half an hour, put the stirred solution into a 100 ml Teflon-lined autoclave, and heat at 180 °C for 24 hours. After washing, centrifuge several times with ethanol, and place the obtained white sample in an oven at 60 °C for 24 hours. Finally, remove the dried powder sample and place it in a muffle furnace at a rate of 5 °C min -1 and heat to 470 °C and then heat for another 1 hour.

[0075] Step 2: Add 176.5 mg of iron acetylacetonate, 178 mg of cobalt acetylacetonate, 128.35 mg of nickel acetylacetonate, 130.78 mg of copper acetylacetonate, and 175.97 mg of manganese acetylacetonate into a mixed solution composed of 50 mL of acetone and 50 mL of ethanol respectively to obtain precursor solutions containing different metals with a concentration of 5×10 -3 M / L. Add 6 mL of each of the prepared precursor solutions into a steel autoclave lined with Teflon, seal the autoclave and place it in an oven to heat at 200 °C for 24 hours, then cool to room temperature, centrifuge at 7000 rpm for 10 min, collect the solid product after centrifugation, wash it twice with acetone, and dry it overnight at 60 °C in a vacuum drying oven to obtain a high-entropy alloy;

[0076] Step 3: Add 10 mg of TiO 2 to 30 mL of water and ultrasonically disperse it to obtain a TiO 2 solution for standby. Add 10 mg of the high-entropy alloy to 10 mL of water and ultrasonically disperse it to obtain a HEA solution (as Figure 3 shown), then add 5.26 mL of the HEA solution to 30 mL of the TiO 2 solution and perform strong magnetic stirring at 10 Hz for 20 min. After the stirring is completed, store it at room temperature for 24 h, then filter, wash it with deionized water, and dry it at 60 °C in a vacuum oven for 12 h to obtain a nanocomposite, that is, a HEA / TiO 2 composite photocatalyst, denoted as 1-HEA / TiO 2 .

[0077] The HEA / TiO 2 composite photocatalysts prepared in Comparative Examples 3-4 were tested for uranium adsorption by the method of Application Example 1, and the results are as Figure 9 shown. It can be seen that in the case of a 5% HEA loading, the uranium removal rate of TiO 2 loaded with HEA is far less than that of HEA loaded with CdS nanorods.

[0078] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the examples shown and described herein.

Claims

1. A method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system, characterized in that: The following steps are involved: Step 1: Prepare CdS nanorods using Cd(NO3)2·4H2O and NH2CSNH2; Step 2, preparing a high entropy alloy using iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate and manganese acetylacetonate; Step 3: Add CdS nanorods into water and disperse them ultrasonically to obtain a CdS solution for later use; add a high entropy alloy into water and disperse them ultrasonically to obtain a high entropy alloy solution; then add the alloy solution into the CdS solution and stir it with a strong magnetic stirrer; after stirring, keep warm for a period of time, filter, wash, and dry to obtain a nanocomposite material, i.e., a HEA / CdS composite photocatalyst.

2. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 1, characterized in that: The step 1 specifically includes: Cd(NO3)2·4H2O and NH2CSNH2 were dissolved in ethylenediamine, stirred evenly, and then the mixed solution was transferred to a polytetrafluoroethylene-lined autoclave and heated in an oven for a period of time, then cooled to room temperature, and the precipitate in the mixed solution was collected by centrifugation, washed, and dried to obtain CdS nanorods.

3. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 1, characterized in that: The step 2 specifically includes: Acetylacetonate iron, acetylacetonate cobalt, acetylacetonate nickel, acetylacetonate copper and acetylacetonate manganese are respectively added to a mixed solution of acetone and ethanol to obtain precursor solutions containing different metals, and the prepared precursor solutions are added together into a Teflon-lined steel autoclave. The autoclave is sealed and placed in an oven to heat for a period of time, and then cooled to room temperature. The solid product is collected by centrifugation, washed and dried to obtain a high entropy alloy.

4. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 2, characterized in that: In the step 1, the molar ratio of Cd(NO3)2·4H2O, NH2CSNH2 and ethylenediamine is 2-4:6-8:200-400, the heating temperature is 180-200°C, and the heating is performed for 12-28 hours.

5. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 2, characterized in that: In the step 1, the centrifugal speed is 6000-8000 rpm, the centrifugation is 8-15 minutes, and when washing the precipitate, it is washed with distilled water and anhydrous ethanol for 3-6 times respectively, and the drying temperature is 50-70° C. and the drying is performed for 5-12 hours.

6. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 3, characterized in that: In the step 2, the molar ratio of iron acetylacetonate, cobalt acetylacetonate, nickel acetylacetonate, copper acetylacetonate and manganese acetylacetonate is 1:1:1:1:1, the volume ratio of acetone to ethanol in the mixed solution of acetone and ethanol is 45-55:45-55, and the metal concentration of the precursor solution is 3×10 -3 ~6×10 -3 M / L.

7. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 3, characterized in that: In the step 2, the heating temperature is 200° C., the heating is performed for 24 hours, the centrifugal speed is 6000-8000 rpm, the centrifugation is performed for 8-15 minutes, and the drying temperature is 50-70° C., and the drying is performed for 5-12 hours.

8. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 1, characterized in that: In the step three, the mass ratio of CdS nanorods to water is 0.8-1.2:2500-3500, the mass ratio of high entropy alloy to water is 0.8-1.2:800-1200, and the volume ratio of CdS solution to high entropy solution is 90-110:3-20.

9. The method for preparing a nanocomposite material for photocatalytic removal of uranium in an acidic uranium-containing wastewater system according to claim 1, characterized in that: In the step 3, the rotation speed of the strong magnetic stirring is 10-30 Hz, the stirring time is 10-30 min, after the stirring is completed, the temperature is kept at 18-30 h, the drying temperature is 55-65° C., and the drying is performed for 8-20 h.

10. An application of a nanocomposite material obtained by the preparation method according to any one of claims 1 to 9, characterized in that: The nanocomposite material is used for removing hexavalent uranium from acidic uranium-containing wastewater with a pH value of 3-8.

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