Preparation method of foamed cerium oxide for photocatalytic sterilization

Abstract

The invention provides a preparation method of foamed cerium oxide for photocatalytic sterilization, and relates to the field of cerium oxide preparation. The preparation method of the foamed cerium oxide for photocatalytic sterilization comprises the following steps: S1, preparing common roasted coffee beans, grinding 2g of coffee beans, 4g of coffee beans, 5g of coffee beans and 8g of coffee beans into powder, and respectively dissolving the powder in 100ml of deionized water; s2, continuously stirring at 80 DEG C for 240 minutes to obtain a coffee extract; and S3, filtering the mixture with water-containing filter paper, marking filtrate as C2, C4, C5 and C8 according to corresponding concentrations of CeO2 (Cn), and storing the filtrate at 4 DEG C for subsequent experiments. According to the invention, cerium oxide has good photocatalytic performance and can generate strong oxidizing free radicals especially under irradiation of ultraviolet light or visible light so as to kill bacteria, and cerium oxide with a foam structure not only can provide a larger illumination reaction area, but also can effectively improve the absorption efficiency of the cerium oxide to ultraviolet light or visible light; therefore, the photocatalytic sterilization performance is enhanced.

Description

Technical Field

[0001] The invention relates to the field of cerium oxide preparation, in particular to a method for preparing foamed cerium oxide for photocatalytic sterilization. Background Art

[0002] As one of the most promising green technologies, photocatalysis has broad prospects in solving energy and environmental safety issues. Photocatalytic technology directly converts solar energy into chemical energy, and the photogenerated electrons and holes generated are widely used, such as reacting to generate superoxide radicals to degrade pollutants, which is an important research topic that is beneficial to the development and progress of human society. In addition, photocatalytic technology has great potential for application in the field of antibacterial.

[0003] CeO2 is used as the base material of photocatalyst, and CeO2 is modified by doping with metal and non-metal elements to make it 3+ The concentration of oxygen vacancies, bandgap width, light response range, separation of photogenerated carriers and production of reactive oxygen species (ROS) are regulated, which greatly promotes the efficacy of photocatalytic antibacterial and prepares high-efficiency broad-spectrum antibacterial agents with visible light response, provides new ideas for the development of photocatalytic antibacterial materials, and provides more options for marine-related industries to solve corrosion and biological fouling problems. It is of great value to marine development and national defense construction, and reduces the safety issues of marine fouling as much as possible.

[0004] However, the current preparation methods of CeO2 are mostly traditional hydrothermal preparation methods, and its morphology is often seen in traditional rods, sheets, spheres and other morphologies. Summary of the invention

[0005] Technical issues solved In view of the shortcomings of the prior art, the present invention provides a method for preparing foamed cerium oxide for photocatalytic sterilization, which solves the problem of less selectivity in solving corrosion and biological fouling problems in marine-related industries.

[0006] (II) Technical solution To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for preparing foamed cerium oxide for photocatalytic sterilization comprises the following steps: S1. Prepare ordinary roasted coffee beans, grind 2 g, 4 g, 5 g and 8 g of coffee beans into powder, and dissolve them in 100 ml of deionized water respectively; S2. Continuously stirring at 80° C. for 240 minutes to obtain a coffee extract; S3. The mixture was filtered with water-containing filter paper, and the filtrate was prepared by CeO2 (C n ) were labeled as C2, C4, C5, and C8 and stored at 4 °C for subsequent experiments; S4. Preparation of cerium oxide nanoparticles using coffee extract and cerium nitrate by green chemistry method: 0.8684 g Ce(NO3)3·6H2O was dissolved in 20 mL distilled water to obtain a 0.1 M solution; S5. 20 ml of coffee extracts of different concentrations were mixed with 20 ml of cerium nitrate solution (0.1 M), and stirred vigorously at 100 °C for 1 hour to obtain a gel-like substance, which was calcined at high temperature (400 °C) in a muffle furnace for 2 hours to obtain a light yellow powder; S6. The obtained powder was ground with an agate mortar and pestle and foamed CeO2 was prepared using coffee extract of different concentrations; Through the above technical scheme, an environmentally friendly, economical, efficient and adjustable approach is provided to prepare foamed cerium oxide materials for photocatalytic sterilization. The use of coffee extract as a green reducing agent can not only improve the performance of the catalyst, but also conform to the concept of sustainable development. At the same time, in practical applications, it can not only provide efficient photocatalytic performance, but also effectively reduce environmental pollution and production costs.

[0007] Furthermore, the pore size of the filter paper in step S3 is 0.22 μm; By adopting the above technical solution, the mixture can be better filtered using water-containing filter paper.

[0008] Furthermore, the stirring speed in step S5 is 1500 rpm; Through the above technical solution, the stirring effect can be effectively improved.

[0009] Furthermore, in step S6, CeO2, such as CeO2 (C n ), where n = 2, 4, 5, 8, corresponding to the coffee extract concentration values.

[0010] Through the above technical solution, it can be better classified.

[0011] (III) Beneficial effects The present invention provides a method for preparing foamed cerium oxide for photocatalytic sterilization, which has the following beneficial effects: The present invention provides a method for preparing foamed cerium oxide for photocatalytic sterilization, and analyzes the photocatalytic antibacterial effect of the prepared photocatalyst to explore its potential application in marine sterilization and antifouling. Pseudomonas aeruginosa and Staphylococcus aureus are taken as target bacteria, and a xenon lamp is used as a visible light source with a power of 500W (λ≥420nm). Under light irradiation, the relevant photocatalyst will produce active oxygen, such as hydroxyl free radicals and superoxide free radicals, which can directly induce lipid peroxidation and bacterial cell wall perforation, leading to membrane leakage, structural damage, and ultimately bacterial death. The photocatalytic sterilization analysis lasted for 12 hours. As shown in the figure, the bacterial colony and fluorescent staining respectively showed live bacteria and dead bacteria, wherein blue fluorescence showed live bacteria and purple showed dead bacteria. It was found that the bactericidal performance of C5 was better than that of other C n Spherical CeO2 (C S ), and the sterilization data show that after 12 hours of culture, the bactericidal effect of C5 on Pseudomonas aeruginosa and Staphylococcus aureus was about 99.06% and 99.43%, respectively. It was observed that within 30 minutes of dark reaction, the bactericidal rate reached 60%. This is because the porous material has a strong adsorption effect on bacteria, so more bacteria are adsorbed on the surface of the material, thereby reducing the bacterial content in the solution. This is due to the fact that C n It has excellent porosity and specific surface area. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the appearance of CeO2 prepared by coffee extract in the present invention; Figure 2 C in the present invention S Electron microscope images of Figure 3 The present invention is a flow chart of preparing cerium oxide nanoparticles by a green chemical method using coffee extract and cerium nitrate; Figure 4 is the XRD pattern of the present invention; Figure 5 It is a schematic diagram of analyzing the photocatalytic antibacterial effect of the present invention; Figure 6 C5 and C S Schematic diagram of the difference in sterilization rate between the two; Figure 7 Schematic diagram of the photoelectrochemical analysis of the present invention. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] Embodiment 1: like Figure 1-7 As shown, the present invention provides a method for preparing foamed cerium oxide for photocatalytic sterilization, comprising the following steps: S1. Prepare ordinary roasted coffee beans, grind 2 g, 4 g, 5 g and 8 g of coffee beans into powder, and dissolve them in 100 ml of deionized water respectively; S2. Continuously stirring at 80° C. for 240 minutes to obtain a coffee extract; S3. The mixture was filtered with water-containing filter paper, and the filtrate was prepared by CeO2 (C n ) were labeled as C2, C4, C5, and C8 and stored at 4 °C for subsequent experiments; S4. Preparation of cerium oxide nanoparticles using coffee extract and cerium nitrate by green chemistry method: 0.8684 g Ce(NO3)3·6H2O was dissolved in 20 mL distilled water to obtain a 0.1 M solution; S5. 20 ml of coffee extracts of different concentrations were mixed with 20 ml of cerium nitrate solution (0.1 M), and stirred vigorously at 100 °C for 1 hour to obtain a gel-like substance, which was calcined at high temperature (400 °C) in a muffle furnace for 2 hours to obtain a light yellow powder; S6. The obtained powder was ground with an agate mortar and pestle and foamed CeO2 was prepared using coffee extract of different concentrations; The invention provides an environmentally friendly, economical, efficient and reliable way to prepare foamed cerium oxide materials for photocatalytic sterilization. The use of coffee extract as a green reducing agent can not only improve the performance of the catalyst, but also conform to the concept of sustainable development. At the same time, in practical applications, it can not only provide efficient photocatalytic performance, but also effectively reduce environmental pollution and production costs.

[0015] The pore size of the filter paper in step S3 is 0.22 μm, so that the mixture can be better filtered using the water-containing filter paper. The stirring speed in step S5 is 1500 rpm, so that the stirring effect can be effectively improved. In step S6, CeO 2， Such as CeO2(C n ), where n=2, 4, 5, 8, corresponding to the concentration values ​​of coffee extract, so that it can be better classified.

[0016] Embodiment 2: like Figure 1 As shown, Figures (ad) and (c) correspond to CeO2 (C n ), SEM images of n=2, 4, 5, 8, prove the foamy porous morphology of CeO2, Figure 2 This is a SEM electron microscope image of spherical CeO2 prepared by the traditional synthesis method as a comparison, and XRD characterization proves that the CeO2 (C n ), n=2, 4, 5, 8 were successfully prepared.

[0017] like Figure 4 Green synthetic foam C n As shown in the X-ray diffraction pattern, it can be seen that the X-ray diffraction peaks of CeO2 prepared by green synthesis are very consistent with the X-ray diffraction peaks of standard cubic phase CeO2 (ICSD: 34-0394) 26. n The diffraction peaks at 28.7°, 33.55°, 47.55° and 56.4° correspond to the (hkl) planes 27 of (111), (200), (220) and (311) diffraction, respectively, which are consistent with the C S Differently, the diffraction peaks of C5 and C8 appear at 59.2°, 69.55°, 76.75°, and 79.2°, corresponding to the (hkl) planes of (222), (400), (331), and (420), respectively.

[0018] like Figure 5 -a, bacterial colonies and fluorescent staining (BB-41266) respectively show live bacteria (shown by blue fluorescence) and dead bacteria (shown by purple fluorescence). The results showed that the bactericidal performance of C5 was significantly better than that of other C n and C S (C prepared by traditional hydrothermal synthesis S ). Through sterilization data Figure 5 -b and c show that after 12 hours of culture, the bactericidal effects of C5 on Pseudomonas aeruginosa and Staphylococcus aureus were approximately 99.06% and 99.43%, respectively, which is significantly better than that of the spherical material C synthesized by traditional hydrothermal synthesis. S Material.

[0019] like Figure 6 As shown in Figure 2, high specific surface area can provide more adsorption sites for bacteria, so this study focused on C5 and C S The specific surface area of ​​C5 and C S The N2 adsorption isotherm is shown in Figure 6 As shown, it is obvious that with C SCompared with the C5, the specific surface area of ​​the former increases exponentially, which is because the foaming structure of the former increases the specific surface area. The specific surface area of ​​C5 (24.9277m 2 / g) is greater than C S (12.6646m 2 / g), which also increases the surface's adsorption capacity and effective inhibition of microorganisms and bacteria.

[0020] To further understand the underlying reasons for the enhanced photocatalytic activity and to investigate the charge separation and transfer efficiency, various photoelectrochemical analyses were performed as shown in 7 , ref. Figure 7 In Figure a, first, the charge transfer resistance was evaluated by electrochemical impedance spectroscopy. S Compared with the C5 material, the Nyquist circle diameter of the C5 material is smaller, which indicates that C5 has better charge transfer characteristics. Figure 7 Figure b, then, the carrier separation and transfer performance was evaluated by transient photocurrent measurement, and it can be seen that the C S In comparison, C5 has a stronger photocurrent response under light excitation, which indicates that the porous foam structure increases light scattering and reflection, which is beneficial to accelerate carrier separation and migration.

[0021] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing foamed cerium oxide for photocatalytic sterilization, characterized in that: The following steps are involved: S1. Prepare ordinary roasted coffee beans, grind 2 g, 4 g, 5 g and 8 g of coffee beans into powder, and dissolve them in 100 ml of deionized water respectively; S2. Continuously stirring at 80° C. for 240 minutes to obtain a coffee extract; S3. The mixture was filtered with water-containing filter paper, and the filtrate was prepared by CeO2 (C n ) were labeled as C2, C4, C5, and C8 and stored at 4 °C for subsequent experiments; S4. Preparation of cerium oxide nanoparticles using coffee extract and cerium nitrate by green chemistry method: 0.8684 g Ce(NO3)3·6H2O was dissolved in 20 mL distilled water to obtain a 0.1 M solution; S5. 20 ml of coffee extracts of different concentrations were mixed with 20 ml of cerium nitrate solution (0.1 M), and stirred vigorously at 100 °C for 1 hour to obtain a gel-like substance, which was calcined at high temperature (400 °C) in a muffle furnace for 2 hours to obtain a light yellow powder; S6. The obtained powder was ground using an agate mortar and pestle and foamed CeO2 was prepared using different concentrations of coffee extract.

2. The method for preparing foamed cerium oxide for photocatalytic sterilization according to claim 1, characterized in that: The pore size of the filter paper in step S3 is 0.22 μm.

3. The method for preparing foamed cerium oxide for photocatalytic sterilization according to claim 1, characterized in that: The stirring speed in step S5 is 1500 rpm.

4. The method for preparing foamed cerium oxide for photocatalytic sterilization according to claim 1, characterized in that: In step S6, CeO2, such as CeO2 (C n ), where n = 2, 4, 5, 8, corresponding to the coffee extract concentration values.

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