Cadmium sulfide-prussian blue-based composite photocatalytic material, and preparation method and application thereof

Abstract

The application discloses a kind of based on cadmium sulfide-prussian blue composite photocatalytic material and its preparation method and application.The composite photocatalytic material includes prussian blue nanoparticles and cadmium sulfide loaded on substrate, wherein, prussian blue nanoparticles are loaded on the surface of substrate, and prussian blue nanoparticles and cadmium sulfide are chemically connected to form heterojunction, and the preparation of photocatalytic material includes: substrate is soaked in the mixed solution of prussian blue nanoparticles and cadmium acetate, after closed reaction, drop sodium sulfide solution, after a period of time, substrate is taken out, washed and dried to obtain the composite photocatalytic material.The uranium adsorption performance of the composite photocatalytic material is good, the structure is stable, easy to recover, raw materials are abundant, reaction conditions are mild, steps are simple, and a large amount of production can be produced by only a small amount of cost, and it has excellent application potential in seawater uranium extraction, radioactive seawater treatment, recovery of precious metals, environmental remediation, industrial wastewater treatment and other fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of material preparation, in particular to a cadmium sulfide-prussian blue-based composite photocatalytic material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of science and technology, the consumption of energy is accelerating, but the main energy used by people, oil, is limited in the earth, and energy shortage has become a problem faced by the whole world. Therefore, finding a sustainable energy source to replace oil has become an urgent problem for countries around the world. Nowadays, various new energy sources have emerged, such as thermal energy, solar energy, water energy, etc., but they all have their own advantages and disadvantages. The thermal power generation by burning coal and other substances is a kind of power generation method with a long history and the most widely used at present, but this energy conversion method often brings serious environmental problems, for example, dust and waste gas generated in the combustion process not only causes weather pollution such as haze, but also harms people's health. Green energy from nature such as solar energy and water energy can produce a large amount of low-carbon electricity and will not bring many pollution problems like the former, but these energy sources are often uncontrollable and are restricted by external factors, and have low conversion efficiency, which cannot solve the energy crisis.

[0003] Nuclear energy, as a kind of green and low-carbon energy, has won people's favor with its advantages of high efficiency, cleanliness and safety, and has the potential to replace oil energy. After half a century of development, the development and use of nuclear energy have been quite mature, but the lack of uranium, its raw material, has become the biggest problem restricting its further development. On land, the reserves of uranium are not high enough to support the long-term use of the whole world. Related personnel found that the reserves of uranium in the ocean are much higher than on land, with 4.5 billion tons, which can be used by the whole human race for thousands of years at the current energy consumption rate. But this brings a new problem: because the ocean is too large, the concentration of uranium elements dispersed in seawater is too low, which is often difficult to extract.

[0004] Photocatalytic materials have entered people's field of vision with high selectivity and high efficiency. Cadmium sulfide, C3N4, titanium dioxide and other semiconductors have the advantages of negative conduction band position and narrow band gap, and become the first choice for preparing nano photocatalytic materials. Semiconductor materials with suitable conduction band position can reduce water-soluble uranyl ions to insoluble uranium compounds, realizing the extraction of uranyl ions. The narrow band gap makes the semiconductor material have excellent light response ability and wide light absorption range, and a large number of photoelectrons can be generated under sunlight conditions to carry out photocatalytic reduction reaction. Therefore, the preparation of nano photocatalytic materials with suitable conduction band position and narrow band gap can provide a new idea for the field of seawater uranium extraction.

[0005] A method for preparing an ethylenediamine-coated cadmium sulfotelluride nanobelt photocatalyst and separating uranium in radioactive wastewater is disclosed in Chinese Patent Publication No. CN 112958150 A, which comprises: preparing cadmium sulfotelluride nanobelt: adding cadmium chloride into ethylenediamine, stirring uniformly, then adding sulfur powder and tellurium powder, continuing to stir uniformly, then adding hydrazine hydrate, stirring for 25-35 min to obtain a mixed solution; transferring the mixed solution into a stainless steel reaction kettle, reacting at 115-125 DEG C for 6-10 h, after the reaction is completed, centrifugally collecting the product, washing with pure water and ethanol three times respectively, and finally drying the precipitate at 55-65 DEG C under vacuum to obtain a cadmium sulfotelluride nanobelt photocatalyst. The invention prepares an ethylenediamine-coated cadmium sulfotelluride nanobelt photocatalyst material, which provides amino groups as adsorption sites, and the introduction of tellurium improves the band gap structure of cadmium sulfide nanobelt. Through the modification of the amino group and the band gap structure on the cadmium sulfotelluride nanobelt, a high-efficiency photocatalytic reduction of hexavalent uranium catalyst is obtained.

[0006] Chinese Patent Publication No. CN 114177922 A discloses a composite catalyst for removing uranium in nuclear waste liquid, which is in the form of a sphere and comprises a carrier and cadmium sulfide loaded on the carrier, wherein the carrier is a spherical carbon aerogel and the cadmium sulfide has sulfur vacancies. The invention also provides a preparation method of the composite catalyst for removing uranium in nuclear waste liquid, which is safe and simple to operate, has high synthesis rate and low cost.

[0007] Chinese Patent Publication No. CN 115228500 A discloses a high-dispersity carbon ring / C3N4 seawater uranium extraction composite material photocatalyst, relating to the field of photocatalytic seawater uranium extraction. In order to solve the technical problem of how to adjust the optimal pH value of photocatalytic reduction of uranium in graphite phase carbon nitride series materials to be close to the seawater environment, a water-soluble graphite phase carbon nitride is first prepared by a molten salt method, and then a high-dispersity carbon ring / C3N4 seawater uranium extraction composite material photocatalyst is prepared by calcining the water-soluble graphite phase carbon nitride with different proportions of glucose in a nitrogen environment. When the glucose content is 5%, the prepared photocatalyst has the best uranium removal rate, and when the pH value is 8, the photocatalyst has the best uranium removal rate of 89.47%, which is suitable for application in seawater environment.

[0008] A method for extracting uranium under visible light using photocatalytic technology is disclosed in Chinese Patent Publication No. CN108906102A. C3N4 is ultrasonically dispersed uniformly, glucose, Cd(NO3)2.4H2O is added, magnetic stirring is performed, L-cysteine is added and stirring is continued, it is moved into a high-pressure reaction kettle and placed in an oven thermostat, cooled and filtered, washed several times with ultrapure water and anhydrous ethanol, freeze-dried, ground and added into a quartz tube, UO2(NO3)2 solution and ultrapure water or seawater are added, N2 gas is blown for a period of time in the dark, and then placed under natural light or xenon lamp irradiation, after 10 minutes, the suspension is filtered. 1 mL of water is added to the obtained solid, placed in air for 24 hours, then 1 mL of 0.1 mol / L Na2CO3 solution is added, desorbed for 30 minutes, then filtered, and the extracted uranium is obtained in the supernatant. The beneficial effect of the present application is that under visible light irradiation, 0.1 mmol / L of uranium in a 15 mL seawater system can be completely extracted in 10 minutes.

[0009] Among the reported preparation methods of nano-photocatalytic materials, the following problems often need to be faced:

[0010] (1) Electron-hole recombination problem: the holes generated in the photocatalytic process will compete with uranyl ions for photoelectrons, which will seriously inhibit the photocatalytic efficiency;

[0011] (2) Material photo-corrosion problem: single-phase materials (such as cadmium sulfide, etc.) are easy to combine with holes, and photo-corrosion phenomenon occurs, resulting in a decrease in the catalytic efficiency of the material;

[0012] (3) Material stability problem: although researchers have developed composite materials with heterojunction structure to solve the above problems. However, the interaction between two or more phases in the composite material is weak, resulting in poor composite stability of the material, which will aggravate the photo-corrosion phenomenon;

[0013] (4) Agglomeration problem of nanomaterials: due to the small size of nanomaterials, agglomeration often occurs in the solution in practical application, resulting in a decrease in specific surface area;

[0014] (5) Difficult to recover, complex preparation steps, and expensive raw materials make it very difficult to put into practical application. SUMMARY

[0015] In view of the above problems, on the basis of cadmium sulfide, a preparation method of a composite nanomaterial with suitable valence band-conduction band complementary relationship and excellent mechanical stability is provided. The cadmium sulfide is combined with Prussian blue nanoparticles to form a heterojunction, so that the photogenerated electrons and holes are separated, the photo-corrosion phenomenon of the cadmium sulfide is effectively inhibited, and a stable chemical bond (CN-Cd) is formed between the cadmium sulfide and the Prussian blue nanoparticles, so that the material can maintain structural stability in various extreme environments. Meanwhile, the composite nanomaterial is combined with a substrate with a large specific surface area to solve the agglomeration problem of the nanomaterial, improve the stability, photocatalytic performance and service life of the nanomaterial, etc. Therefore, the application provides a cadmium sulfide / Prussian blue composite photocatalytic material which is simple in steps, economical and feasible, rich in raw materials and wide in application range.

[0016] The application allows the Prussian blue nanoparticles to be loaded on the surface of the substrate by a hydrothermal synthesis method, and then allows the cadmium sulfide to be generated on the surface of the Prussian blue in an in-situ growth manner and form a heterojunction structure with the Prussian blue. After the reaction is completed, the substrate is taken out, washed and dried. The obtained material is the cadmium sulfide / Prussian blue composite photocatalytic material. The photocatalytic performance of the cadmium sulfide / Prussian blue photocatalytic material can be adjusted by controlling the type of the Prussian blue, the type of the substrate, the volume ratio of the Prussian blue-acetic acid cadmium solution and the sodium sulfide solution and the soaking time of the substrate.

[0017] The technical scheme of the application is as follows:

[0018] The photocatalytic material comprises a composite nanomaterial loaded on a substrate, the composite nanomaterial comprises Prussian blue nanoparticles and cadmium sulfide, the Prussian blue nanoparticles are loaded on the surface of the substrate, the surface of the Prussian blue nanoparticles is connected with the cadmium sulfide through a stable chemical bond, and the cadmium sulfide and the Prussian blue nanoparticles form a heterojunction, so that the photogenerated electrons and holes are separated and the photo-corrosion phenomenon of the cadmium sulfide is effectively inhibited. Specifically, the Prussian blue nanoparticles and the cadmium sulfide are chemically connected by a stable CN-Cd bond, so that the material can maintain structural stability in various extreme environments.

[0019] The Prussian blue nanoparticles are at least one of cobalt / iron Prussian blue nanoparticles Co Fe-PBA, nickel / iron Prussian blue nanoparticles Ni Fe-PBA, manganese / iron Prussian blue nanoparticles Mn Fe-PBA, cobalt / nickel Prussian blue nanoparticles Co Ni-PBA, manganese / chromium Prussian blue nanoparticles Mn Cr-PBA, copper / nickel Prussian blue nanoparticles Cu Ni-PBA, nickel / cobalt / iron Prussian blue nanoparticles Ni Co Fe-PBA, Prussian yellow nanoparticles PY and Prussian white nanoparticles PW.

[0020] Preferably, the Prussian blue nanoparticles are cobalt / nickel Prussian blue nanoparticles Co Ni-PBA.

[0021] The substrate is at least one of nanosponge, porous silica, basswood, graphene oxide, carbon nanotube, Fe3O4, balsa wood, nanofiber, covalent organic framework material COF, metal organic framework material MOF, and porous aromatic framework PAF.

[0022] Preferably, the substrate is a metal organic framework material (MOF).

[0023] The substrate has a large specific surface area, and after being combined with the composite nanomaterial, the problem of agglomeration of the nanomaterial can be solved, and the stability, photocatalytic performance, and service life of the nanomaterial can be improved.

[0024] The preparation method of the photocatalytic material comprises the following steps:

[0025] (1) Prussian blue nanoparticles are added to pure water under the condition of a hot water bath at room temperature to 50°C and pH=5-10, and stirred for 0.1-2h to obtain solution ①; solution ① is mixed with cadmium acetate (Cd(CH3COO)2) under the condition of room temperature to 60°C and pH=5-9, and stirred for 0.1-2h to obtain solution ②;

[0026] In the solution ② obtained in step (1), the mass ratio of the Prussian blue nanoparticles to cadmium acetate is 0.01-40:0.2-200.

[0027] (2) After solution ② is uniformly dispersed, a substrate is added to solution ②, the substrate is fully soaked in the solution, and the reaction is sealed for 0.1-12h;

[0028] In step (2), the soaking time of the substrate is 0.1-24h.

[0029] (3) Under the condition of a water bath at 10-60°C and pH=5-10, a sodium sulfide solution (Na2S) is added dropwise to solution ② in which the substrate is soaked, in this process, cadmium sulfide grows in situ on the surface of the Prussian blue material and forms a heterojunction;

[0030] In step (3), the mass ratio of the sodium sulfide to the Prussian blue nanoparticles is 0.1-20:1, and the volume ratio of solution ② in which the substrate is soaked to the sodium sulfide solution is 1-20:1.

[0031] Preferably, the volume ratio of solution ② in which the substrate is soaked to the sodium sulfide solution is 3:1.

[0032] Preferably, in step (3), the dropping speed of the sodium sulfide solution is 0.1-2mm / s.

[0033] (4) Take out the substrate and wash it with pure water and ethanol several times in turn, and dry it for 2h-24h to obtain the dried composite photocatalytic material.

[0034] The application includes uranium extraction from seawater, radioactive mining wastewater treatment, noble metal recovery, environmental remediation, industrial wastewater treatment and the like.

[0035] Preferably, the composite photocatalytic material is used for photocatalytic uranium extraction from seawater.

[0036] The detection steps of the photocatalytic uranium extraction performance of the composite photocatalytic material are as follows: after the dried composite photocatalytic material is added to a uranyl ion aqueous solution, sampling is performed after a period of reaction under light irradiation, and the supernatant is obtained by centrifugation, and the content of uranyl ions in the supernatant is tested by ICP-MS, and the higher the uranium extraction amount, the better the extraction performance of the composite photocatalytic material.

[0037] The application also includes loading other nanomaterials or functional groups on the surface of the cadmium sulfide-prussian blue composite photocatalytic material, so that the inherent performance can be further optimized or more excellent performance can be added, and the composite photocatalytic material is used in the fields of uranium extraction from seawater, radioactive mining wastewater treatment, noble metal recovery, environmental remediation, industrial wastewater treatment and the like.

[0038] Preferably, the nanomaterial is MXene or titanium dioxide (TiO2) or a carbon nanotube.

[0039] Preferably, the functional group is an amide oxime group or a hydroxyl group or an amino group.

[0040] The application has the following advantages and beneficial effects:

[0041] The photocatalytic material in the application has excellent adsorption performance for uranium, and has excellent structural stability, maintains excellent separation performance in various extreme environments, the entire uranium extraction operation process is simple, the reaction conditions (such as temperature, PH, reaction time, etc.) are mild, and the material is easy to recycle and has excellent recycling performance. The photocatalytic material needs raw materials, substrates, which are rich in types and reserves, have a wide source range, and can be produced in large quantities with only a small amount of cost. The preparation method of the photocatalytic material can prepare a large amount of materials with excellent photocatalytic performance under mild reaction conditions by a simple synthesis method, and has excellent application potential in the fields of uranium extraction from seawater, radioactive seawater treatment, recovery of noble metals, environmental remediation, industrial wastewater treatment and the like. In addition, the prepared composite material can introduce more functional groups or load other polymers to optimize its performance, and also adds a new preparation method to the preparation field of composite adsorption materials. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1A flow chart for preparing the cadmium sulfide-prussian blue composite photocatalytic material.

[0043] Figure 2 Effects of different raw materials on the extraction performance of uranium.

[0044] Figure 3 Effects of different substrates on the extraction performance of uranium.

[0045] Figure 4 Effects of the volume ratio of prussian blue-cadmium acetate solution to sodium sulfide solution on the extraction performance of uranium.

[0046] Figure 5 Effects of uranium-containing solutions with different pH values on the extraction performance of uranium. DETAILED DESCRIPTION

[0047] The present application is described in more detail by the following examples, but the examples do not constitute a limitation on the present application.

[0048] Example 1

[0049] Co Fe-PBA was selected as the prussian blue raw material required for the reaction, and nanosponge was selected as the substrate. Under the condition of a temperature of 30℃, 0.08g Co Fe-PBA was added to 50mL pure water, the pH value was adjusted to 6.2, and 50℃ hot water bath stirring was performed for 20min to obtain solution ①; under the condition of a temperature of 50℃, 0.2g cadmium sulfide was fully dissolved in 50mL pure water, and then mixed with solution ①, and the pH value was adjusted to 7.4 to obtain solution ②; after uniform mixing, the nanosponge was immediately placed in the mixed solution, and sealed reaction was performed at 50℃ for 1h; under the condition of a temperature of 50℃, 0.18g sodium sulfide was dispersed in 50mL pure water, and the pH value was adjusted to 7.4 to obtain solution ③, and then solution ③ was added to solution ② at a speed of 0.5mm / s through an automatic titration system. After the solution reaction was completed, the nanosponge was taken out, washed several times, and dried to obtain the cadmium sulfide / prussian blue composite photocatalytic material.

[0050] The dried nanosponge was added to 50mL of a uranyl ion aqueous solution with a concentration of 50ppm and a pH value of 6, and sampling was performed after reaction for 1h under light conditions, and the supernatant was obtained by centrifugation, and the content of uranyl ions in the solution was tested by ICP-MS. Through test analysis, the extraction amount of the cadmium sulfide / prussian blue nanosponge for uranyl ions was 1011.2mg / g.

[0051] Examples 2-10

[0052] Co Fe-PBA, Ni Fe-PBA, Mn Fe-PBA, Co Ni-PBA, Mn Cr-PBA, Cu Ni-PBA, Ni Co Fe-PBA, PY, PW were selected as Prussian blue nanoparticles raw materials, respectively, and the rest of the conditions were the same as in Example 1. The results showed that the Ni Co-PBA-based nanosponge had better extraction performance (see Figure 2 ).

[0053] Test Type of feed material Uranium extraction (mg / g) Example 2 Co Fe-PBA 811.2 Example 3 Co Ni-PBA 1113.1 Example 4 Ni Fe-PBA 998.5 Example 5 Mn Fe-PBA 861.1 Example 6 Mn Cr-PBA 918.5 Example 7 Cu Ni-PBA 965.2 Example 8 Ni Co Fe-PBA 965.1 Example 9 PY 795.7 Example 10 PW 886.4

[0054] Examples 11-18

[0055] Porous silica, carbon nanotubes, Fe3O4, balsa wood, linden wood, COFs, MOFs, PAFs were selected as substrates, respectively, and the rest of the conditions were the same as in Example 1. The results showed that the cadmium sulfide / Prussian blue composite MOFs material had the best extraction performance (see Figure 3 ).

[0056]

[0057]

[0058] Examples 19-24

[0059] The volume ratio of Prussian blue-cadmium acetate solution to sodium sulfide solution was 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, respectively, and the rest of the conditions were the same as in Example 1. The results showed that when the volume ratio of Prussian blue-cadmium acetate solution to sodium sulfide solution was 3:1, the performance of cadmium sulfide / Prussian blue nanosponge was the best (see Figure 4 ).

[0060] Test Volume ratio Uranium extraction (mg / g) Example 19 1:1 367.6 Example 20 2:1 895.3 Example 21 3:1 1069.3 Example 22 4:1 898.4 Example 23 5:1 792.5 Example 24 6:1 712.6

[0061] Examples 25-30

[0062] The pH value of the 16 ppm uranyl ion aqueous solution was adjusted to 1-11, respectively, and the rest of the conditions were the same as in Example 1.

[0063] Test Solution pH value Uranium extraction (mg / g) Example 25 1 387.6 Example 26 2 698.8 Example 27 3 788.6 Example 28 4 1001.2 Example 29 5 1099.1 Example 30 6 1121.3 Example 31 7 1007.6 Example 32 8 1006.8 Example 33 9 876.5 Example 34 10 712.3 Example 35 11 384.2

[0064] The results showed that the extraction content of cadmium sulfide / Prussian blue nanosponge for uranium was as high as 1000 or more in the pH range of 1-11 (see Figure 5 ).

Claims

1. Application of a cadmium sulfide-prussian blue-based composite photocatalytic material in uranium extraction from seawater, characterized in that: The composite photocatalytic material comprises a composite nanomaterial loaded on a substrate, the composite nanomaterial comprises Prussian blue nanoparticles and cadmium sulfide, the Prussian blue nanoparticles are loaded on the surface of the substrate, and the Prussian blue nanoparticles and the cadmium sulfide are chemically connected by a stable CN-Cd bond; the cadmium sulfide and the Prussian blue nanoparticles form a heterojunction. The Prussian blue nanoparticles are at least one of cobalt / iron Prussian blue nanoparticles Co Fe-PBA, nickel / iron Prussian blue nanoparticles Ni Fe-PBA, manganese / iron Prussian blue nanoparticles Mn Fe-PBA, cobalt / nickel Prussian blue nanoparticles CoNi-PBA, manganese / chromium Prussian blue nanoparticles Mn Cr-PBA, copper / nickel Prussian blue nanoparticles Cu Ni-PBA, and nickel / cobalt / iron Prussian blue nanoparticles Ni Co Fe-PBA. The substrate is at least one of nanosponge, porous silica, graphene oxide, carbon nanotube, Fe3O4, nanofiber, metal organic framework material, and porous aromatic framework.

2. Use according to claim 1, characterized in that: The preparation method of the composite photocatalytic material comprises the following steps: (1) under the conditions of room temperature to 50 DEG C and pH = 5-10, Prussian blue nanoparticles are added to pure water to obtain solution ①; under the conditions of room temperature to 60 DEG C and pH = 5-9, solution ① is blended with cadmium acetate to obtain solution ②; (2) the substrate is added to solution ②, the substrate is soaked in the solution and sealed for 0.1-12 h; (3) under the conditions of 10-60 DEG C and pH = 5-10, a sodium sulfide solution is added to solution ② in which the substrate is soaked; (4) the substrate is taken out and washed with pure water and ethanol in sequence, and is dried to obtain the composite photocatalytic material.

3. Use according to claim 2, characterized in that: In solution ② obtained in step (1), the mass ratio of Prussian blue nanoparticles to cadmium acetate is 0.01-40:0.2-200.

4. Use according to claim 2, characterized in that: In step (3), the mass ratio of sodium sulfide to Prussian blue nanoparticles is 0.1-20:

1.

5. Use according to claim 2, characterized in that: In step (3), the volume ratio of solution ② in which the substrate is soaked to the sodium sulfide solution is 1-20:

1.

6. Use according to claim 1, characterized in that: The application also includes the use of the cadmium sulfide-Prussian blue composite photocatalytic material for uranium extraction from seawater after loading other nanomaterials or functional groups on the surface of the cadmium sulfide-Prussian blue composite photocatalytic material.

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