Cerium dioxide-based nanopowder, antibacterial film, and preparation method and application of cerium dioxide-based nanopowder

Abstract

The present application relates to a kind of ceria-based nanopowder and its preparation method and application.Cerium dioxide-based nanopowder preparation method includes the following steps: (1) cerium salt is mixed with water, optionally adding salt to provide doped metal, to make precursor solution;(2) first, add hydrogen peroxide solution to precursor solution to adjust pH to 2-4, then add alkali solution with concentration of 1.2-1.8M to adjust pH to 8.5-9.5, to make suspension, control the system temperature of this step is 20-30℃;(3) wash the suspension to neutral or close to neutral, collect the solid particles in the suspension, then dry at 70-90℃, to obtain cerium dioxide-based nanopowder.The preparation method of the present application is simple, low cost, without using additional structure-directing agent, alcohol solvent, etc., and the preparation condition is mild, can be prepared at room temperature and normal pressure;The cerium dioxide nanopowder prepared has truncated octahedron morphology, small particle size, large specific surface area, and has better antibacterial performance.

Description

Technical Field

[0001] This invention relates to a cerium dioxide-based nanopowder, an antibacterial film, and a method for preparing and applying the cerium dioxide-based nanopowder. Background Technology

[0002] Cerium dioxide (CeO2) is an inexpensive and widely used light rare earth oxide. Compared to bulk materials, nanoscale cerium dioxide exhibits altered electronic structures and increased specific surface areas, often displaying novel physical properties (such as lattice diffusion, lattice boundary transitions, and blue shift of the UV absorption peak) and higher chemical activity. The physicochemical properties of nanoscale cerium dioxide are closely dependent on its size, morphology, and crystal structure; therefore, constructing novel cerium dioxide nanostructures and achieving their controllable preparation is of great significance.

[0003] In recent years, a series of nano-cerium dioxide with different morphologies have been successfully synthesized. For example, patent CN107746069B prepared cerium dioxide with different morphologies using a hydrothermal method. It used Ce(NO3)3·6H2O as the cerium source and NaOH as the precipitant. The reaction was carried out at 180±5℃ for 20 to 24 hours, and the calcination temperature was 300±5℃ for 20 to 24 hours. Cubic CeO2 was prepared with a side length of 7.5 to 40 nm and a thickness of 7.5 to 40 nm. The patent also describes the preparation of nanoparticle-type CeO2 at 100±5℃ for 20–24 h, with a nanoparticle size of 66.7–102.3 nm. Furthermore, it describes the preparation of nanorod-type CeO2 at 100±5℃ for 20–24 h, with a nanorod length of 115.5–192.3 nm and an average diameter of 9.0 nm. However, the hydrothermal method requires high reaction temperatures and pressures, resulting in harsh reaction conditions and demanding equipment requirements.

[0004] For example, patent CN 104445340 B uses cerium nitrate as the cerium source, hexadecyltrimethylammonium bromide as the structure directing agent, and deionized water and ethanol as solvents to generate octahedral cerium oxide by reacting at 150°C for 22-24 hours. This method has a high reaction temperature and requires the use of alcohol solvents and structure directing agents, which increases the difficulty and cost of post-processing.

[0005] For example, patent CN 102730740 B uses cerium nitrate as the cerium source, gelatin as the structure directing agent, and deionized water as the solvent to generate cubic cerium dioxide at 70°C. This method requires gelatin, which increases the cost, and gelatin can only dissolve in water at around 70°C.

[0006] In summary, further research and improvement are needed on the preparation methods of cerium dioxide-based nanopowders in order to construct novel cerium dioxide nanostructures and achieve their controllable preparation. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing cerium dioxide-based nanopowder that is simple to operate, has mild reaction conditions and low cost. The cerium dioxide-based nanopowder prepared by this method is truncated octahedral and has the advantages of small particle size, large specific surface area and good antibacterial properties.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing cerium dioxide-based nanopowder, carried out under normal pressure, includes the following steps:

[0010] (1) Mix cerium salt with water and selectively add salts that provide doping metals to prepare a precursor solution;

[0011] (2) First, add hydrogen peroxide solution to the precursor solution to adjust the pH to 2-4, and then add 1.2-1.8M alkaline solution to adjust the pH to 8.5-9.5 to make a suspension. Control the system temperature of this step to 20-30℃.

[0012] (3) Wash the suspension until it is neutral or close to neutral, collect the solid particles in the suspension, and then dry it at 70-90°C to obtain cerium dioxide-based nanopowder.

[0013] This invention improves the preparation method, especially by adding hydrogen peroxide solution to the precursor solution and controlling the temperature of the system in step (2), the concentration of the added alkali solution and its dosage, so that the morphology of cerium dioxide is transformed into a truncated octahedron with a larger specific surface area, while significantly reducing the particle size of cerium dioxide nanopowder.

[0014] Preferably, the cerium dioxide-based nanoparticles have a particle size of no more than 10 nm. Unless otherwise specified, the particle size in this invention refers to the average particle size.

[0015] More preferably, the cerium dioxide-based nanoparticles have a particle size of no more than 5 nm.

[0016] More preferably, the cerium dioxide-based nanoparticles have a particle size of no more than 4 nm.

[0017] In some embodiments, the cerium dioxide-based nanoparticles have a particle size of 3–4 nm.

[0018] Preferably, the cerium dioxide-based nanopowder has a specific surface area of ​​135–155 m². 2 / g.

[0019] Preferably, the cerium dioxide-based nanopowder is in the form of a truncated octahedron.

[0020] Preferably, the cerium dioxide-based nanopowder is doped with any one of metallic silver, copper, or molybdenum.

[0021] Preferably, the molar ratio of the doped metal to cerium in the precursor solution is (1-7):100, for example, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, or 7:100.

[0022] Preferably, the cerium salt is a trivalent cerium salt.

[0023] More preferably, the concentration of cerium in the precursor solution is 0.05–0.15 M.

[0024] Preferably, the alkaline solution is selected from ammonia water or sodium hydroxide aqueous solution.

[0025] Preferably, the salt providing the doped metal is selected from silver nitrate, copper nitrate, or molybdenum chloride.

[0026] Preferably, the drying time in step (3) is 20 to 28 hours.

[0027] A second objective of this invention is to provide a cerium dioxide-based nanopowder, which is prepared according to the preparation method described above.

[0028] A third objective of this invention is to provide an application of the cerium dioxide-based nanopowder as described above, wherein the cerium dioxide-based nanopowder is used as a bactericidal and antibacterial material.

[0029] A fourth objective of this invention is to provide an antibacterial membrane comprising a substrate layer and an antibacterial membrane layer disposed on one side of the substrate layer, wherein the antibacterial membrane layer comprises cerium dioxide-based nanopowder as described above. By adding cerium dioxide-based nanopowder to the antibacterial membrane layer, the antibacterial membrane layer can effectively kill bacteria and viruses, exhibiting good antibacterial effect.

[0030] Preferably, the substrate layer is a PET film.

[0031] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0032] The preparation method of the present invention is simple to operate and low in cost. It does not require the use of additional structure directing agents, alcohol solvents, etc., and can be prepared at room temperature and pressure under mild conditions. The prepared cerium dioxide nanopowder is truncated octahedral, with small particle size, large specific surface area and good antibacterial properties. Attached Figure Description

[0033] Figure 1 The image shows the XRD pattern of the cerium dioxide nanopowder in Example 1.

[0034] Figure 2 The Raman spectrum of the cerium dioxide nanopowder in Example 1;

[0035] Figure 3 This is a transmission electron microscope image of the cerium dioxide nanopowder in Example 1;

[0036] Figure 4 The images shown are transmission electron microscope (TEM) images of the nanoparticles in Examples 2 to 10, where a, b, c, d, e, f, g, h, and i correspond to the nanoparticles in Examples 2 to 10, respectively. Detailed Implementation

[0037] Nanoscale CeO2 possesses unique properties and applications, leading to increasingly stringent requirements for the morphology and particle size of CeO2 nanopowders. Currently, hydrothermal synthesis of CeO2 nanopowders is commonly employed. This method utilizes specialized reaction vessels to provide a physicochemical environment unattainable at ambient temperature and pressure, allowing chemical reactions to occur in water and other solvents, resulting in a range of powders with diverse morphologies. However, this method demands demanding experimental equipment, involves lengthy preparation processes, and consumes significant energy.

[0038] Through extensive research, the inventors discovered that by adjusting the pH of a cerium-containing precursor solution with hydrogen peroxide, followed by the addition of an alkaline solution and precise control of its concentration and amount, truncated octahedral CeO2 nanopowder can be obtained at room temperature and pressure without the need for structure-directing agents or alcohol solvents. This CeO2 nanopowder possesses a smaller particle size and a larger specific surface area. The following further elaborates on the invention.

[0039] A method for preparing cerium dioxide-based nanopowder includes the following steps:

[0040] (1) Mix cerium salt with water and selectively add salts that provide doping metals to prepare a precursor solution;

[0041] (2) First, add hydrogen peroxide solution to the precursor solution to adjust the pH to 2-4, and then add 1.2-1.8M alkaline solution to adjust the pH to 8.5-9.5 to make a suspension. Control the system temperature in this step to 20-30℃.

[0042] (3) Wash the suspension until it is neutral or close to neutral, collect the solid particles in the suspension, and then dry it at 70-90°C to obtain cerium dioxide-based nanopowder.

[0043] In step (1), the cerium salt can be, for example, cerium nitrate hexahydrate or a similar cerium salt.

[0044] The inventors discovered that this preparation method can satisfy the doping requirements of most metal elements. Preferably, the doping metal is selected from silver, copper, and molybdenum. For example, silver nitrate can be used as the salt providing silver, copper nitrate as the salt providing copper, and molybdenum chloride as the salt providing molybdenum. Doping with these metals can further enhance the antibacterial properties of cerium dioxide-based nanopowders. Furthermore, the molar ratio of cerium to the doping metal in the precursor solution is 100:(3-7), for example, 100:3, 100:4, 100:5, 100:6, 100:7, etc.; the concentration of cerium in the precursor solution is preferably 0.05-0.15 M, more preferably 0.05-0.1 M.

[0045] The precursor solution can be prepared at room temperature (20-30℃) and atmospheric pressure (i.e., one atmosphere).

[0046] In step (2), by adding hydrogen peroxide solution, the Ce in the precursor solution can be reduced. 3+ Convert as much as possible to Ce 4+ This is beneficial for improving the catalytic reduction performance of CeO2 nanopowder. Preferably, the concentration of the hydrogen peroxide solution is 25–35 vol%, for example, 25 vol%, 26 vol%, 27 vol%, 28 vol%, 29 vol%, 30 vol%, 31 vol%, 32 vol%, 33 vol%, 34 vol%, and 35 vol%.

[0047] In step (2), the suspension is also prepared at room temperature and pressure.

[0048] The inventors discovered that, under normal temperature and pressure, the concentration of the added alkaline solution significantly affects the morphology and particle size of CeO2-based nanoparticles. When the alkaline solution concentration is below 1 M, the CeO2-based nanoparticles are irregular in shape with a particle size of 8–14 nm; when the alkaline solution concentration is above 2 M, the CeO2-based nanoparticles are rod-shaped with a length of 123.5–168.3 nm and an average diameter of 18.0 nm. By controlling the alkaline solution concentration, CeO2-based nanoparticles with truncated octahedral structures and a particle size not exceeding 10 nm can be prepared, compared to rod-shaped nanoparticles (with a specific surface area of ​​approximately 87–104.9 m²). 2 / g), cube (specific surface area approximately 13.6m²) 2 / g), the truncated octahedron has a higher specific surface area (specific surface area can reach 135m²). 2 The larger the specific surface area (g and above), the better the catalytic reduction performance. Preferably, the solution concentration is controlled at 1.2 to 1.8 M, for example 1.2 M, 1.3 M, 1.4 M, 1.5 M, 1.6 M, 1.7 M, 1.8 M.

[0049] In step (2), an alkaline solution is added dropwise to adjust the pH to 8.5 to 9.5, and more preferably to adjust the pH to 8.7 to 9.3, for example 9.

[0050] In step (3), the suspension is rinsed with deionized water, and the number of rinses is not specifically limited. After the suspension is rinsed to neutral, it is separated into layers using a centrifuge, the supernatant is removed, the remaining solid particles are retained, and then sent to an oven to dry for 20 to 28 hours, preferably 22 to 26 hours.

[0051] The above preparation method has at least the following advantages:

[0052] (1) The CeO2-based nanoparticles prepared by this method have extremely small sizes (up to 3-4 nm). These tiny nanoparticles have higher fluidity, making them easier to reach the site of infection when used as bactericidal or antibacterial materials, thereby eliminating bacteria. The nanoparticles are truncated octahedrons, which have a larger specific surface area. The larger the specific surface area, the more CeO2 it contains. 3+ / Ce 4+ Yes, and more Ce 3+ / Ce 4+ It can enhance catalytic reduction performance, release more active oxygen, and has a positive impact on improving bactericidal performance.

[0053] (2) The preparation method is simple to operate, the preparation conditions are mild, the preparation process is short and the energy consumption is low.

[0054] (3) This preparation method is applicable to the doping of most metal elements. By doping with metals such as silver, copper, and molybdenum, the antibacterial properties of the material can be further improved.

[0055] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0056] Unless otherwise specified, the following examples and comparative examples were carried out under normal pressure.

[0057] Example 1

[0058] A method for preparing cerium oxide nanopowder includes the following steps:

[0059] (1) Dissolve an appropriate amount of cerium nitrate (Ce(NO3)3·6H2O) in deionized water to prepare a 0.1M solution, and stir it thoroughly for 5 minutes at room temperature (25℃) with the speed set to 500 rpm.

[0060] (2) Hydrogen peroxide (H2O2, 30 vol%) was added dropwise to the above solution to adjust the pH to approximately 3.0, resulting in a pale yellow solution. Then, ammonia (NH3·H2O, 1.5 M) was added dropwise to the pale yellow solution to adjust the pH to approximately 9.0. During this process, orange-yellow solid particles began to precipitate, forming a suspension. The system temperature was maintained at 25°C during this step.

[0061] (3) The above suspension was rinsed with sufficient deionized water to remove residual chemical components. The rinsing process was repeated about 10 times until the pH of the suspension reached neutral. Then, the suspension was separated by centrifugation to remove the upper clear liquid, leaving the remaining solid particles. The suspension was then dried in an oven at 80°C for 24 hours. After drying, the suspension was ground to obtain cerium dioxide nanoparticles.

[0062] The cerium dioxide nanopowder prepared by this method has a molar conversion rate of 88.3%, which is high and has good uniformity.

[0063] Example 2-10

[0064] A method for preparing cerium oxide-based nanopowder includes the following steps:

[0065] (1) Dissolve an appropriate amount of cerium nitrate (Ce(NO3)3·6H2O) in deionized water to prepare a 0.1M solution. Stir the solution continuously at room temperature (25℃) for 5 minutes with a speed of 500 rpm. Add metal salts with concentrations of 3 / 5 / 7 mol% to the solution according to the formula in Table 1 below to prepare a precursor solution.

[0066] (2) Hydrogen peroxide (H2O2, 30 vol%) was added dropwise to the above precursor solution to adjust the pH to approximately 3.0, resulting in a pale yellow solution. Then, ammonia (NH3·H2O, 1.5 M) was added dropwise to the pale yellow solution to adjust the pH to approximately 9.0. During this process, orange-yellow solid particles began to precipitate, resulting in a suspension. The system temperature was maintained at 25°C during this step.

[0067] (3) The above suspension was rinsed with sufficient deionized water to remove residual chemical components. The rinsing process was repeated about 10 times until the pH of the suspension reached neutral. Then, the suspension was separated by centrifugation to remove the upper clear liquid, leaving the remaining solid particles. The suspension was then dried in an oven at 80°C for 24 hours. After drying, the suspension was ground to obtain cerium dioxide-based nanoparticles.

[0068] The performance tests are shown in Table 1 below.

[0069] Table 1

[0070]

[0071]

[0072] The particle size test method in Table 1 above is as follows: the length of 20 lattices is directly measured by acquiring electron lens (TEM) images, and the average value is calculated to determine the particle size.

[0073] Morphology testing method: Morphology is obtained by direct observation through acquired electron lens (TEM) images;

[0074] Specific surface area was determined by the BET test. See reference: Mehmood, R., Ariotti, N., Yang, JL, Koshy, P., Sorrell, CCPH-responsive morphology-controlled redox behavior and cellular uptake of nanoceria in fibrosarcoma. ACS Biomater., 2018; 4(3), 1064–1072.

[0075] The antibacterial performance was tested using the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), as detailed in the literature: Martínez, CGA. MN, Martínez, GF et al. Synthesis and antibacterial activity of silver nanoparticles with different sizes. J Nanopart Res., 2018; 10, 1343–1348.

[0076] Comparative Examples 1-6

[0077] The preparation method of cerium oxide nanopowder in this comparative example is roughly the same as that in Example 1, except for the ammonia concentration and the temperature and pH of the system in step (2). The specific differences between each comparative example and Example 1 are shown in Table 2 below.

[0078] Table 2

[0079]

[0080]

[0081] In the table above, N / A indicates synthesis failure, primarily likely due to excessively low pH, leading to an imbalance of OH groups. - The concentration was too low, precipitation was insufficient, and no pale yellow particles (cerium dioxide) were precipitated, resulting in synthesis failure.

[0082] Comparative Examples 7-10

[0083] The preparation method of cerium oxide nanopowder in this comparative example is roughly the same as that in Example 1, except that the raw materials are different. The differences between each comparative example and Example 1 are shown in Table 3 below.

[0084] Table 3

[0085]

[0086] Comparative Example 11

[0087] The preparation method of cerium oxide nanopowder in this comparative example is roughly the same as that in Example 1, except that after step (3) is completed, the cerium dioxide nanopowder is calcined at a temperature of 280°C for 24 hours.

[0088] The cerium dioxide nanopowder finally obtained in this comparative example has a spherical morphology with a particle size of 8-10 nm, and its antibacterial properties are somewhat reduced.

[0089] The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and implement the invention. However, this description should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be included within the scope of protection of the invention.

Claims

1. A method for preparing cerium dioxide-based nanopowder, characterized in that: The preparation method is carried out under normal pressure and includes the following steps: (1) Mix cerium salt with water, with or without adding salt to provide the dopant metal, to prepare a precursor solution; (2) First, add hydrogen peroxide solution to the precursor solution to adjust the pH to 2~4, and then add 1.2~1.8M alkaline solution to adjust the pH to 8.5~9.5 to make a suspension. Control the system temperature in step (2) to 20~30℃. (3) Wash the suspension until it is neutral or close to neutral, collect the solid particles in the suspension, and then dry it at 70~90℃ to obtain cerium dioxide-based nanopowder; The cerium dioxide-based nanoparticles are truncated octahedral in shape, with a particle size not exceeding 10 nm and a specific surface area of ​​135-155 m². 2 / g.

2. The preparation method according to claim 1, characterized in that: The cerium dioxide-based nanopowder has a particle size of no more than 5 nm.

3. The preparation method according to claim 1, characterized in that: The cerium dioxide-based nanopowder is doped with any one of the following metals: silver, copper, and molybdenum.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the doped metal to cerium in the precursor solution is (1~7):

100.

5. The preparation method according to claim 1, characterized in that: The cerium salt is a trivalent cerium salt, and / or the concentration of cerium in the precursor solution is 0.05~0.15M.

6. The preparation method according to claim 1, characterized in that: The alkaline solution is selected from ammonia water or sodium hydroxide aqueous solution; and / or, The salt providing the doped metal is selected from silver nitrate, copper nitrate, or molybdenum chloride.

7. The preparation method according to claim 1, characterized in that: The drying time in step (3) is 20~28h.

8. A cerium dioxide-based nanopowder, characterized in that: The cerium dioxide-based nanopowder is prepared by the method described in any one of claims 1 to 7.

9. The application of the cerium dioxide-based nanopowder as described in claim 8, characterized in that: The application of the cerium dioxide-based nanopowder as a bactericidal or antibacterial material.

10. An antibacterial film, characterized in that: The antibacterial film includes a substrate layer and an antibacterial film layer disposed on one side of the substrate layer, wherein the antibacterial film layer includes cerium dioxide-based nanopowder as described in claim 8.

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