Method for killing pathogenic bacteria by using Fe3O4 nanoparticles loaded with ruthenium atoms

Abstract

The invention discloses a method for killing pathogenic bacteria by using Fe3O4 nano-particles loaded with ruthenium atoms, which comprises the following steps: putting the Fe3O4 nano-particles loaded with ruthenium atoms and peroxymonosulfate into a water body containing the pathogenic bacteria to carry out catalytic reaction so as to realize inactivation treatment on the pathogenic bacteria, the preparation process of the Fe3O4 nano-particles loaded with ruthenium atoms comprises the following steps: firstly preparing the Fe3O4 nano-particles, and then mixing the Fe3O4 nano-particles with a mixed solution of ruthenium trichloride and a sodium hydroxide solution for reaction to obtain the Fe3O4 nano-particles loaded with ruthenium atoms. According to the method, ruthenium atoms are anchored on the Fe3O4 nanoparticles, efficient catalysis of peroxymonosulfate is improved, rapid separation of the catalyst is achieved, and the method has the advantages of being easy to operate, high in bacterium inactivation speed, short in time, rapid in catalyst separation and recovery and the like and can be widely applied to the field of killing of pathogenic bacteria in water.

Description

Technical Field

[0001] This invention belongs to the field of nanocatalysis and wastewater disinfection, specifically relating to a method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms. Background Technology

[0002] Ensuring water resource security is of paramount importance to human life, as the presence of numerous pathogenic microorganisms in water poses a serious threat to human health. According to the World Health Organization, approximately 505,000 people die annually from diarrhea-related causes, resulting from drinking water contamination by pathogenic microorganisms. Pathogenic microorganisms in the aquatic environment mainly include bacteria, viruses, and protozoa. Notably, high concentrations of these pathogens are often present in natural water bodies. Studies indicate that the microbial risk posed by pathogens is induced by low doses, and these risks are often highly infectious, with a short timeframe required to induce severe symptoms. Therefore, microbial risk is a crucial issue that must be prioritized for control during water treatment.

[0003] Advanced oxidation processes (AOPs) are widely considered a highly efficient wastewater treatment method. AOPs work by generating sulfate radicals (SO4· ... - ), hydroxyl radicals (·OH), superoxide radicals (·O2) - ) and singlet oxygen ( 1 Reactive oxygen species (ROS) such as O2 are used to inactivate bacteria. Among various active oxygen species (AOPs), persulfate-mediated AOPs show great potential for bacterial inactivation due to their simplicity and ability to generate high ROS levels. Persulfate (PMS), as a representative of persulfates, exhibits extremely high oxidizing activity. Noble metals and their metal oxides are effective catalysts for accelerating the breaking of O2 bonds in PMS to generate ROS. Ru and its metal oxides, as excellent heterogeneous persulfate catalysts, can effectively generate ROS, but developing high-performance, low-cost Ru-based catalysts for pathogenic microorganism inactivation remains a significant challenge. Furthermore, although many researchers have developed nanoscale heterogeneous catalysts, this also brings new challenges to catalyst recovery. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for disinfecting pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, which have high catalytic activity, good bactericidal and inactivation effects and are easy to recycle. The method mainly uses magnetic iron as a catalyst to achieve efficient inactivation of bacteria in water, and the catalyst can be quickly separated from the system.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms includes the following steps: adding Fe3O4 nanoparticles loaded with ruthenium atoms and persulfate into water containing pathogens to carry out a catalytic reaction, thereby achieving the inactivation of pathogens in the water.

[0007] The preparation method of the Fe3O4 nanoparticles loaded with ruthenium atoms includes the following steps:

[0008] S1. Mix iron salt, anhydrous sodium acetate, ethylene glycol and polyethylene glycol to obtain a mixed solution;

[0009] S2. The resulting mixed solution was subjected to a hydrothermal reaction at 200℃~205℃ to obtain Fe3O4 nanoparticles;

[0010] S3. The obtained Fe3O4 nanoparticles are mixed with a mixture of ruthenium trichloride and sodium hydroxide solution, wherein the mass ratio of Fe3O4 nanoparticles to ruthenium trichloride is 50-52:1, and the mixture is reacted at 50℃-55℃ to obtain Fe3O4 nanoparticles loaded with ruthenium atoms.

[0011] In the preferred embodiment of the above-mentioned method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, the amount of Fe3O4 nanoparticles loaded with ruthenium atoms added is 0.10 g to 0.12 g per liter of water containing pathogens, and the amount of persulfate added is 20 mg to 22 mg per liter of water containing pathogens.

[0012] The method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, as described above, preferably includes one or more of Streptococcus suis, Escherichia coli, and Staphylococcus aureus.

[0013] In the above-described method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, preferably, in step S3, the ratio of ruthenium trichloride to sodium hydroxide solution is 6.8 mg to 7.0 mg: 93 mL to 95 mL, and the concentration of sodium hydroxide solution is 0.020 mol / L to 0.022 mol / L.

[0014] In the preferred embodiment of the above-mentioned method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, in step S1, the ratio of the iron salt, anhydrous sodium acetate, ethylene glycol, and polyethylene glycol is 1.35g–1.37g: 3.60g–3.80g: 43mL–45mL: 5mL–7mL, the iron salt is FeCl3·6H2O, the mixing is carried out under stirring conditions, and the stirring time is 30min–35min.

[0015] In the preferred embodiment of the above-mentioned method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, step S2 involves the following steps: the hydrothermal reaction time is 10-11 hours; after the hydrothermal reaction, the reaction product is washed and dried, the washing is performed using ethanol, the drying is performed under vacuum, the vacuum drying temperature is 60-65°C, and the vacuum drying time is 6-7 hours.

[0016] In the preferred embodiment of the above-mentioned method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, in step S3, the reaction time is 8-9 hours. After the reaction is completed, the reaction product is washed and dried. The washing is done with water, and the drying is done under vacuum. The temperature of the vacuum drying is 60-65°C, and the time of the vacuum drying is 10-11 hours.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] (1) This invention provides a method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms. Magnetic iron is used as the base catalyst to achieve efficient inactivation of bacteria in water. By anchoring ruthenium atoms (Ru) onto Fe3O4, which possesses properties such as stability, biocompatibility, surface interaction, and high specific saturation magnetization, the utilization rate of ruthenium atoms is improved, providing more active sites for the efficient catalysis of persulfate (PMS). Simultaneously, the magnetic strength of Fe3O4 is utilized to rapidly separate and recover the catalyst using an external magnetic field, achieving efficient elimination and inactivation of pathogens in water while rapidly recovering the catalyst. The method of this invention has advantages such as simple operation, high inactivation efficiency, and simple and rapid catalyst separation, enabling efficient inactivation of pathogens in wastewater. Taking *Escherichia coli* as an example, under the catalytic action of the ruthenium-loaded Fe3O4 magnetic catalyst, persulfate (PMS) is rapidly activated, and *E. coli* is completely inactivated within 5 minutes. Similarly, for *Staphylococcus aureus*, under the catalytic action of the ruthenium-loaded Fe3O4 magnetic catalyst, persulfate (PMS) is rapidly activated, and *S. aureus* is completely inactivated within 20-30 minutes. For *Streptococcus suis*, under the catalytic action of the ruthenium-loaded Fe3O4 magnetic catalyst, persulfate (PMS) is rapidly activated, and *Streptococcus suis* is inactivated by 5 log within 30 minutes. Therefore, the ruthenium-loaded Fe3O4 magnetic catalyst of this invention can achieve rapid inactivation of pathogens, providing a feasible solution for efficient wastewater disinfection and potentially replacing traditional water disinfection methods. Furthermore, the catalyst can be rapidly separated from the system.

[0019] (2) The Fe3O4 nanoparticles loaded with ruthenium atoms used in the method of the present invention have the advantages of high catalytic activity and simple and rapid catalyst recovery. The preparation method is simple to operate and no other impurities are introduced during the reaction. The catalyst has good application potential. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of the ruthenium-loaded Fe3O4 magnetic catalyst prepared in Example 1 of the present invention.

[0021] Figure 2 The image shows the XRD pattern of the Fe3O4 magnetic catalyst loaded with ruthenium atoms prepared in Example 1 of this invention.

[0022] Figure 3 This is a hysteresis loop diagram of the Fe3O4 magnetic catalyst loaded with ruthenium atoms prepared in Example 1 of the present invention.

[0023] Figure 4 This is a magnetic test image of the Fe3O4 magnetic catalyst loaded with ruthenium atoms prepared in Example 1 of the present invention.

[0024] Figure 5 The diagram shows the bactericidal effect of the ruthenium-loaded Fe3O4 magnetic catalyst (Fe3O4-Ru) of Example 1 of the present invention and the catalysts of control groups 1-3 in activating persulfate to inactivate Escherichia coli.

[0025] Figure 6 The images show the bactericidal effects of the ruthenium-loaded Fe3O4 magnetic catalysts in Examples 1-3 on Escherichia coli, Staphylococcus aureus, and Streptococcus suis. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0027] Example 1:

[0028] A method for eliminating pathogens using ruthenium-loaded Fe3O4 nanoparticles according to the present invention specifically involves using the magnetic catalyst of ruthenium-loaded Fe3O4 nanoparticles to activate persulfate (potassium persulfate can be used) to inactivate Escherichia coli in water, including the following steps:

[0029] Weigh 0.01 g of ruthenium-loaded Fe3O4 nanoparticles (Fe3O4-Ru) and add them to 100 mL of solution with an initial concentration of 1 × 10⁻⁶. 7The solution of E. coli at cfu / mL was placed on a constant temperature shaker, and then persulfate was added at a dosage of 20 mg / L to carry out a catalytic reaction, thereby completing the inactivation treatment of E. coli in the water.

[0030] In this embodiment, the preparation method of Fe3O4 nanoparticles loaded with ruthenium atoms includes the following process:

[0031] S1. Preparation of mixed solution:

[0032] Dissolve 1.35g FeCl3·6H2O and 3.6g anhydrous NaAc in 45mL ethylene glycol and 5mL polyethylene glycol, and mix with stirring for 30min to obtain a mixed solution.

[0033] S2, Hydrothermal reaction generates Fe3O4 nanoparticles:

[0034] The mixed solution obtained in step S1 was transferred to a reaction vessel for hydrothermal reaction at a temperature of 200°C for 10 hours. After the reaction was completed, the reaction product was washed and filtered at least three times with ethanol, and then dried under vacuum at 60°C in an oven for 6 hours to obtain Fe3O4 nanoparticles.

[0035] S3, Immersion:

[0036] First, 7.0 mg of ruthenium trichloride (analytical grade) was dissolved in a beaker containing 95 mL of 0.021 mol / L sodium hydroxide solution to obtain a ruthenium trichloride / sodium hydroxide mixture. Then, 0.35 g of Fe3O4 nanoparticles obtained in step S2 were added to the ruthenium trichloride / sodium hydroxide mixture, and the mixture was stirred at 50 °C for 8 h. After the reaction was completed, the reaction product was washed and filtered at least 3 times with ultrapure water, and then vacuum dried at 60 °C for 10 h in a vacuum drying oven to obtain a ruthenium-loaded Fe3O4 nanoparticle magnetic catalyst, denoted as Fe3O4-Ru.

[0037] Figure 1 , Figure 2 , Figure 3 The images shown are scanning electron microscope (SEM) images, X-ray diffraction (XRD) patterns, and magnetic strength evidence of the ruthenium-loaded Fe3O4 nanoparticle magnetic catalyst prepared in this embodiment. Figure 1 As can be seen, the material exhibits a microspherical structure with a particle size of approximately 100-200 nm. This microspherical structure increases the contact area between persulfate (PMS) and single-atom ruthenium, providing a basis for the efficient activation of PMS and the rapid inactivation of E. coli. Simultaneously, the clean, cluster-free surface of the material indicates that ruthenium atoms are well-loaded on the Fe3O4 surface. Figure 2The XRD pattern shows that after ruthenium atom loading, the position of the characteristic peak of the material remains unchanged and is in good agreement with the standard pattern, which suggests that the successful synthesis of cubic Fe3O4 and the anchoring of ruthenium atoms did not cause any change in the crystal structure of the material. Figure 3 The hysteresis loop diagram shows that Fe3O4-Ru is superparamagnetic, with both resonance and coercivity being 0. Figure 4 This indicates that the catalyst completely separates from the system within 10 seconds under the action of an external magnetic field, and the Fe3O4 nanoparticle magnetic catalyst loaded with ruthenium atoms prepared in this invention has good magnetic strength.

[0038] Control group 1: Fe3O4 nanoparticles loaded with ruthenium atoms were replaced with Fe3O4 nanoparticles (Fe3O4-Ru), and all other conditions were the same.

[0039] Control group 2: Only Fe3O4 nanoparticles loaded with ruthenium atoms (Fe3O4-Ru) were added, without PMS, and all other conditions were the same.

[0040] Control group 3: Only PMS was added, and all other conditions were the same.

[0041] The change in the number of E. coli after coating reflects the change in the concentration of E. coli in the water. The number of E. coli in the reaction solution was recorded at 0 min, 2 min, 4 min, 6 min, 8 min and 10 min to obtain the corresponding concentration of E. coli in the solution at different reaction times. The number of E. coli at different reaction times was calculated according to the formula N = logC, where C is the concentration of E. coli at different times and N is the logarithm of the concentration.

[0042] Figure 5 This diagram illustrates the bactericidal effect on *Escherichia coli* under different reaction system conditions in this embodiment. Figure 5 It is evident that the ruthenium-loaded Fe3O4 nanoparticles (Fe3O4-Ru) of this invention, when activating persulfate, can achieve a 100% removal rate of Escherichia coli in water within 5 minutes. Its catalytic efficiency is significantly higher than that of Fe3O4 catalysis alone, and its inactivation efficiency is also far superior to that of pure persulfate and pure ruthenium-loaded Fe3O4 magnetic catalysts. Therefore, the ruthenium-loaded Fe3O4 magnetic nanoparticles of this invention exhibit higher catalytic efficiency and better inactivation effect on Escherichia coli.

[0043] Example 2

[0044] A method for eliminating pathogenic bacteria using ruthenium-loaded Fe3O4 nanoparticles according to the present invention specifically involves using the magnetic catalyst of ruthenium-loaded Fe3O4 nanoparticles to activate persulfate for inactivation treatment of Staphylococcus aureus in water. The ruthenium-loaded Fe3O4 nanoparticles used are the ruthenium-loaded Fe3O4 nanoparticles (Fe3O4-Ru) prepared in Example 1. The method includes the following steps:

[0045] Weigh 0.01 g of ruthenium-loaded Fe3O4 nanoparticles (Fe3O4-Ru) and add them to 100 mL of a solution with an initial concentration of 1 × 10⁻⁶. 7 The solution of Staphylococcus aureus at cfu / mL was placed on a constant temperature shaker, and then PMS was added at a dosage of 20 mg / L to carry out a catalytic reaction, thereby completing the inactivation treatment of Staphylococcus aureus in the water.

[0046] The change in the number of Staphylococcus aureus after coating reflects the change in the concentration of Staphylococcus aureus in the water. The number of Staphylococcus aureus in the reaction solution was recorded at 0 min, 2 min, 4 min, 6 min, 8 min, 10 min, 20 min and 30 min to obtain the corresponding concentration of Staphylococcus aureus in the solution at different reaction times. According to the formula N = logC (where C is the concentration of Staphylococcus aureus at different times and N is the logarithm of the concentration), the number of Staphylococcus aureus corresponding to different reaction times was calculated.

[0047] Example 3

[0048] A method for eliminating pathogens using ruthenium-loaded Fe3O4 nanoparticles according to the present invention specifically involves using the magnetic catalyst of ruthenium-loaded Fe3O4 nanoparticles to activate persulfate for inactivation of Streptococcus suis in water. The ruthenium-loaded Fe3O4 nanoparticles used are the ruthenium-loaded Fe3O4 nanoparticles (Fe3O4-Ru) prepared in Example 1. The method includes the following steps:

[0049] Weigh 0.01 g of ruthenium-loaded Fe3O4 nanoparticles (Fe3O4-Ru) and add them to 100 mL of a solution with an initial concentration of 1 × 10⁻⁶. 7 The solution of Streptococcus suis in cfu / mL was placed on a constant temperature shaker, and then PMS was added at a dosage of 20 mg / L to carry out a catalytic reaction, thereby completing the inactivation treatment of Streptococcus suis in the water.

[0050] The change in the number of Streptococcus suis after coating reflects the change in the concentration of Streptococcus suis in the water. The number of Streptococcus suis in the reaction solution was recorded at 0 min, 2 min, 4 min, 6 min, 8 min, 10 min, 20 min and 30 min to obtain the corresponding concentration of Streptococcus suis in the solution at different reaction times. The number of Streptococcus suis corresponding to different reaction times was calculated according to the formula N = logC (where C is the concentration of Streptococcus suis at different times and N is the logarithm of the concentration).

[0051] Figure 6 The images show the bactericidal effects of the ruthenium-loaded Fe3O4 nanoparticle magnetic catalysts used in Examples 1-3 against *Escherichia coli*, *Staphylococcus aureus*, and *Streptococcus suis*. Figure 6 It is evident that the ruthenium-loaded Fe3O4 nanoparticles activated persulfate of this invention exhibit inactivation effects on both Gram-negative and Gram-positive bacteria. Specifically, this system demonstrates the highest inactivation efficiency against Gram-positive bacteria, namely *Escherichia coli*, achieving 100% inactivation within 5 minutes. Gram-negative bacteria, such as *Staphylococcus aureus*, are completely inactivated within 20-30 minutes. Furthermore, the system also shows good inactivation effects against *Streptococcus suis* within 30 minutes. Therefore, the ruthenium-loaded Fe3O4 nanoparticle magnetic catalyst of this invention possesses very high catalytic efficiency and a very broad range of pathogen inactivation effects.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms, characterized in that, The process includes the following steps: Fe3O4 nanoparticles loaded with ruthenium atoms and persulfate are introduced into water containing pathogens to carry out a catalytic reaction, thereby achieving the inactivation of pathogens in the water. The preparation method of the Fe3O4 nanoparticles loaded with ruthenium atoms includes the following steps: S1. Mix iron salt, anhydrous sodium acetate, ethylene glycol and polyethylene glycol to obtain a mixed solution; S2. The resulting mixed solution was subjected to a hydrothermal reaction at 200℃~205℃ to obtain Fe3O4 nanoparticles; S3. The obtained Fe3O4 nanoparticles are mixed with a mixture of ruthenium trichloride and sodium hydroxide solution, wherein the mass ratio of Fe3O4 nanoparticles to ruthenium trichloride is 50-52:1, and the mixture is reacted at 50℃-55℃ to obtain Fe3O4 nanoparticles loaded with ruthenium atoms.

2. The method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms according to claim 1, characterized in that, The amount of Fe3O4 nanoparticles loaded with ruthenium atoms added is 0.10g to 0.12g per liter of water containing pathogens, and the amount of persulfate added is 20mg to 22mg per liter of water containing pathogens.

3. The method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms according to claim 1, characterized in that, The pathogens include one or more of Streptococcus suis, Escherichia coli, and Staphylococcus aureus.

4. The method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms according to any one of claims 1 to 3, characterized in that, In step S3, the ratio of ruthenium trichloride to sodium hydroxide solution is 6.8 mg to 7.0 mg : 93 mL to 95 mL, and the concentration of sodium hydroxide solution is 0.020 mol / L to 0.022 mol / L.

5. The method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms according to any one of claims 1 to 3, characterized in that, In step S1, the ratio of the iron salt, anhydrous sodium acetate, ethylene glycol, and polyethylene glycol is 1.35g~1.37g∶3.60g~3.80g∶43mL~45mL∶5mL~7mL, the iron salt is FeCl3·6H2O, the mixing is carried out under stirring conditions, and the stirring time is 30min~35min.

6. The method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms according to any one of claims 1 to 3, characterized in that, In step S2: the hydrothermal reaction takes 10-11 hours; after the hydrothermal reaction, the reaction product is washed and dried. The washing is done with ethanol, and the drying is done under vacuum. The vacuum drying temperature is 60-65°C, and the vacuum drying time is 6-7 hours.

7. The method for eliminating pathogens using Fe3O4 nanoparticles loaded with ruthenium atoms according to any one of claims 1 to 3, characterized in that, In step S3, the reaction time is 8h to 9h. After the reaction is completed, the reaction product is washed and dried. The washing is done with water, and the drying is done under vacuum. The temperature of the vacuum drying is 60℃ to 65℃, and the time of the vacuum drying is 10h to 11h.

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