A bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material, its preparation method, and its application in water treatment.

Abstract

This invention discloses a bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material, its preparation method, and its application in water treatment, belonging to the field of water pollution treatment. The preparation method includes the following steps: (1) adding AgNPs particles and MOFs nanoparticles to an organic solvent and stirring to obtain AgNPs / MOFs composite particles; (2) adding the AgNPs / MOFs composite particles to a bio-enzyme solution and stirring to obtain bio-enzyme / AgNPs / MOFs composite particles; (3) adding the bio-enzyme / AgNPs / MOFs composite particles to a polylactic acid solution, dispersing them evenly, and then electrospinning to obtain the bio-enzyme / AgNPs / MOFs / PLA composite fiber membrane material. The bio-enzyme / MOFs / AgNPs / PLA composite fiber material of this invention can achieve the dual effects of efficiently removing heavy metals from water and antibacterial properties.

Description

Technical Field

[0001] This invention belongs to the field of water pollution treatment, specifically relating to a bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material, its preparation method, and its application in water treatment. Background Technology

[0002] Environmental pollution, especially water pollution, has become a global challenge, and its long-term impact on human health and the Earth's ecosystems is increasingly attracting public and scientific attention. The health and ecological hazards caused by heavy metal and microbial pollution are particularly serious. Their presence not only threatens water safety and quality but also poses a severe threat to biodiversity and ecological balance. Heavy metal pollution mainly originates from industrial activities, agricultural emissions, and urban sewage. These heavy metal elements (such as lead and cadmium) are difficult to degrade naturally once they enter water bodies due to their persistence and bioaccumulation capacity. Long-term accumulation can severely damage aquatic ecosystems and even affect human health through the food chain. On the other hand, microbial pollution, especially the presence of pathogens such as bacteria, viruses, and parasites, directly threatens public health and safety. Traditional methods for treating microbial pollution, such as chlorination disinfection and ultraviolet irradiation, while effective to some extent, also have problems such as generating harmful byproducts and high energy consumption. Against this backdrop, developing a highly efficient and environmentally friendly water treatment material that can simultaneously address both heavy metal and microbial pollution is an urgent problem to be solved.

[0003] Existing technologies in water pollution treatment, especially when using materials such as metal-organic frameworks (MOFs), silver nanoparticles (AgNPs), and bioenzymes, have some significant drawbacks and limitations. These drawbacks mainly stem from the properties of the materials themselves, their interaction mechanisms, and their performance in practical applications. Specifically, the main drawbacks and their causes include:

[0004] (1) AgNPs’ tendency to aggregate: Silver nanoparticles tend to aggregate in water, which reduces their surface area and activity, thus affecting their antibacterial effect.

[0005] (2) Biocompatibility and environmental impact issues: AgNPs particles may be potentially toxic to humans and the environment. They may accumulate through the food chain, posing a threat to aquatic organisms and human health. In addition, although MOFs have strong adsorption capacity, they are not easy to recycle and can easily cause secondary pollution when they enter water bodies.

[0006] (3) Stability and activity of biological enzymes: biological enzymes may lose their activity in complex environments (such as high temperature and extreme pH value), which limits their effectiveness in practical applications.

[0007] (4) The preparation process is complex: The process of combining MOFs, AgNPs and biological enzymes is complex and requires precise control of the proportion and interaction of each component, which increases the difficulty and cost of preparation.

[0008] (5) Insufficient mechanical strength: Some MOF-based fiber membranes may not have sufficient mechanical strength and durability, which limits their reliability in practical water treatment applications.

[0009] (6) Narrow application scope: Currently, polyvinyl alcohol is mostly used as the electrospinning substrate, but polyvinyl alcohol is easily soluble in water, which limits its application in water treatment.

[0010] In summary, the shortcomings of existing technologies are mainly due to the inherent chemical and physical properties of the materials, the complexity of their interactions, and performance limitations in practical application environments. Therefore, developing novel, more efficient, and more stable water treatment materials, as well as improving the synthesis and application strategies of existing materials, are crucial to addressing these challenges. Summary of the Invention

[0011] This invention simultaneously immobilizes silver nanoparticles and bio-enzymes within metal-organic frameworks (MOFs), forming a composite material with synergistic antibacterial effects. Silver nanoparticles provide powerful antibacterial activity, while bio-enzymes enhance the catalytic degradation of specific biopollutants. This combination not only improves the overall antibacterial performance of the material but also strengthens its ability to combat bacterial resistance. This invention utilizes polylactic acid (PLA) as the matrix for the electrospun membrane, effectively immobilizing silver nanoparticles and enabling their slow release during use. This not only maintains a long-lasting antibacterial effect but also significantly reduces the rapid release of silver ions, avoiding potential secondary pollution to the environment. The antibacterial membrane of this invention is not limited to antibacterial functions but also possesses the ability to degrade specific pollutants due to the inclusion of bio-enzymes. This makes the membrane material widely applicable in environmental protection, biomedicine, food preservation, and other fields. This invention employs a unique electrospinning technology, combining MOFs, silver nanoparticles, and bio-enzymes in a composite preparation process. This novel method not only improves the material preparation efficiency but also makes the membrane performance more controllable, providing new ideas for the development of high-performance antibacterial materials.

[0012] The objective of this invention is achieved through the following technical solutions.

[0013] In a first aspect, the present invention provides a method for preparing a bio-enzyme / AgNPs / MOFs / PLA composite fiber membrane material for water treatment, comprising the following steps:

[0014] (1) Add AgNPs particles and MOFs nanoparticles to an organic solvent, stir and react, and dry the mixture to obtain AgNPs / MOFs composite particles.

[0015] (2) The AgNPs / MOFs composite particles were added to the bio-enzyme solution, stirred, centrifuged, and sonicated to obtain bio-enzyme / AgNPs / MOFs composite particles;

[0016] (3) The bio-enzyme / AgNPs / MOFs composite particles are added to a polylactic acid solution and dispersed evenly to obtain a spinning solution. The spinning solution is electrospun to obtain a bio-enzyme / AgNPs / MOFs / PLA composite fiber membrane material.

[0017] Metal-organic frameworks (MOFs) have shown great potential in water treatment due to their unique physicochemical properties. MOFs are a class of porous materials composed of metal ions or metal clusters linked to organic ligands through strong covalent or coordination bonds. They possess high specific surface area, diverse chemical compositions, tunable pore structures, and excellent adsorption properties, making them ideal for removing heavy metal ions from water. Meanwhile, silver nanoparticles (AgNPs) are widely used in water treatment and biomedicine due to their excellent antibacterial properties. AgNPs can effectively inhibit bacterial growth and reproduction by interacting with bacterial cell walls and membranes, disrupting bacterial life activities. However, using AgNPs alone for water treatment may be limited by their stability and regeneration capacity, and the potential environmental risks cannot be ignored.

[0018] Against this backdrop, the introduction of bioenzymes offers a new research direction in this field. As biocatalysts, bioenzymes can promote specific reactions under environmentally friendly conditions, potentially enhancing the performance of MOFs / AgNPs systems. Simultaneously, the introduction of polylactic acid (PLA) fiber membranes provides new possibilities for the preparation of highly efficient and multifunctional water treatment materials. PLA is a biodegradable thermoplastic polyester with good biocompatibility, mechanical strength, and processing properties. Effectively combining MOFs, AgNPs, and bioenzymes, and utilizing PLA fiber membranes as a carrier, can achieve not only the dual removal of heavy metals and microorganisms but also ensure the mechanical stability and practical applicability of the material.

[0019] In this invention, metal-organic frameworks (MOFs) possess high specific surface area, diverse chemical composition, tunable pore structure, and excellent adsorption performance, enabling efficient removal of metal ions from water. Silver nanoparticles (AgNPs) exhibit outstanding antibacterial properties. AgNPs can effectively inhibit bacterial growth and reproduction by interacting with bacterial cell walls and membranes, disrupting bacterial life activities. Biocatalysts, acting as biocatalysts, can promote specific reactions under environmentally friendly conditions, enhancing the performance of the MOFs / AgNP system. Polylactic acid (PLA) fiber membranes are biodegradable thermoplastic polyesters with good biocompatibility, mechanical strength, and processing properties. This invention effectively combines MOFs, AgNPs, and biocatalyst fiber membranes, utilizing PLA fiber membranes as a carrier, achieving not only dual removal of heavy metals and microorganisms but also ensuring the mechanical stability and practical applicability of the material.

[0020] In step (1):

[0021] In some embodiments, the MOF nanoparticles include ZIF-8 nanoparticles, ZIF-67 nanoparticles, and HKUST-1 nanoparticles.

[0022] In some embodiments, the MOF nanoparticles are prepared by adding an organic ligand, a metal source, and a dispersant to a solvent, mixing them evenly, and then sonicating, reacting, and washing to obtain MOF nanoparticles.

[0023] Preferably, when the MOF nanoparticles are ZIF-8 nanoparticles,

[0024] The organic ligand is at least one selected from 2-methylimidazole, 4,5-dimethylimidazole, benzimidazole, 1H-imidazole, and 2-ethylimidazole; the metal source is at least one selected from zinc nitrate hexahydrate ([Zn(NO3)2·6H2O]), zinc chloride (ZnCl2), zinc sulfate (ZnSO4), and zinc acetate (Zn(CH3COO)2); the solvent is at least one selected from dimethyl sulfoxide, methanol, and N,N-dimethylformamide; and the dispersant is sodium dodecyl sulfate. The metal source and organic ligand are selected from at least one of SDS, polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP); the mass ratio of the metal source to the organic ligand is at least one of 1:(1-4); the amount of dispersant added is 0.1% to 1% of the mass of the metal source; the ultrasonication time is 10-30 min; the reaction temperature is 70-90℃; the stirring speed of the reaction is 300-500 rpm; the reaction time is 8-12 h; and the cleaning is performed by washing with methanol 2-4 times.

[0025] Preferably, when the MOF nanoparticles are ZIF-67 nanoparticles,

[0026] The organic ligand is at least one of 2-methylimidazole, 4,5-dimethylimidazole, benzimidazole, 1H-imidazole, and 2-ethylimidazole; the metal source is at least one of cobalt nitrate hexahydrate ([Co(NO3)2·6H2O]), cobalt chloride (CoCl2), cobalt sulfate (CoSO4), and cobalt acetate (Co(CH3COO)2); the solvent is at least one of dimethyl sulfoxide, methanol, and N,N-dimethylformamide; the dispersant is at least one of sodium dodecyl sulfate (SDS), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP); the mass ratio of the metal source to the organic ligand is at least one of 1:(1-4); the amount of dispersant added is 0.1% to 1% of the mass of the metal source; the ultrasonication time is 10-30 min; the reaction temperature is 70-90℃; the stirring speed is 300-500 rpm; the reaction time is 8-12 h; and the cleaning is performed 2-4 times with methanol.

[0027] Preferably, when the MOF nanoparticles are HKUST-1 nanoparticles,

[0028] The organic ligand is phthalic acid (BDC); the metal source is at least one of copper nitrate trihydrate ([Cu(NO3)2·3H2O]), copper chloride (CuCl2), copper sulfate (CuSO4), and copper acetate (Cu(CH3COO)2); the solvent is at least one of dimethyl sulfoxide, ethanol, and N,N-dimethylformamide; the dispersant is at least one of sodium dodecyl sulfate (SDS), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP); the mass ratio of the metal source to the organic ligand is at least one of 1:(1-4); the amount of dispersant added is 0.1% to 1% of the mass of the metal source; the ultrasonication time is 10-30 min; the reaction temperature is 20-35℃; the stirring speed is 300-500 rpm; the reaction time is 6-24 h; and the cleaning is performed 2-4 times with ethanol.

[0029] In step (1):

[0030] In some embodiments, the mass ratio of the silver nanoparticles to the MOF nanoparticles is at least one of (1-2):(1-4).

[0031] In some embodiments, the organic solvent is one or more of ethanol, methanol, dimethyl sulfoxide, and N,N-dimethylformamide.

[0032] In some embodiments, the temperature of the stirring reaction is 25-35°C, and the stirring reaction time is 1-3 hours.

[0033] In some embodiments, the drying temperature is 30-70°C and the drying time is 6-10 hours.

[0034] In step (2):

[0035] In some embodiments, the biological enzyme includes one or more of lysozyme, catalase, ursylase, and antistreptococcal enzyme.

[0036] In some embodiments, the concentration of the bioenzyme in the bioenzyme solution is 0.1-2 mg / mL.

[0037] In some embodiments, the solvent of the bioenzyme solution is a phosphate buffer solution with a pH of 6.8-7.8.

[0038] In some embodiments, the mass ratio of the AgNPs / MOFs composite particles to the bioenzyme solution is (300-1500) mg: 1 L.

[0039] In some embodiments, the stirring temperature is 30-50°C, the stirring time is 1-4 hours, and the stirring speed is 100-500 rpm.

[0040] In some embodiments, the centrifugation speed is 8000-12000 rpm, and the centrifugation time is 5-10 min.

[0041] In some embodiments, the ultrasound duration is 3-5 minutes.

[0042] In step (3):

[0043] In some embodiments, the mass concentration of the polylactic acid solution is 8-12%.

[0044] In some embodiments, the solvent for the polylactic acid solution is one or more of ethyl acetate, dimethyl sulfoxide, and tetrahydrofuran.

[0045] In some embodiments, the mass ratio of the bio-enzyme / AgNPs / ZIF-8 composite particles to the polylactic acid solution is 1:(100-300).

[0046] In some embodiments, the electrospinning conditions are: voltage 12-18kV, flow rate 2-4mL / h, and collection distance 12-18cm.

[0047] Secondly, the present invention provides a bioenzyme / MOFs / AgNPs / PLA composite fiber membrane material, wherein the bioenzyme / ZIF-8 / AgNPs / PLA composite fiber membrane material is prepared by the preparation method described above.

[0048] Thirdly, the present invention provides an application of a bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material in water treatment.

[0049] The bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material provided by this invention can adsorb heavy metals in polluted water and kill pathogens such as bacteria, viruses and parasites in the water.

[0050] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0051] (1) This invention effectively combines MOFs, AgNPs and biological enzymes, and uses PLA as a carrier to prepare a biological enzyme / MOFs / AgNPs / PLA composite fiber material that can achieve the dual effects of efficient removal of heavy metals in water and antibacterial properties.

[0052] (2) Bioenzymes have low stability and are easily deactivated in the environment, which limits their application in water treatment. In this invention, the bioenzyme is loaded onto AgNPs particles, which improves the stability of the bioenzyme and increases its effectiveness in practical applications. At the same time, the bioenzyme has catalytic antibacterial effect, which can realize the synergistic antibacterial effect of the bioenzyme and AgNPs, thereby reducing the amount of AgNPs used and reducing the cost of membrane materials.

[0053] (3) In this invention, MOFs, AgNPs and biological enzymes can promote each other, improve the effect of composite fiber materials in removing heavy metals and microorganisms, and fix AgNPs on MOFs particles to avoid the problem of AgNPs agglomeration.

[0054] (4) The present invention fixes bio-enzyme / MOFs / AgNPs particles in PLA, which can realize the recycling of MOFs particles and AgNPs, improve the stability of AgNPs, and avoid the problem of AgNPs easily remaining in water, thus avoiding secondary pollution of water.

[0055] (5) Currently, polyvinyl alcohol is mostly used as the electrospinning substrate in electrospinning. Polyvinyl alcohol is easily soluble in water, which limits its application in water treatment. This invention innovatively uses PLA as the electrospinning substrate. PLA is insoluble in water and can provide sufficient mechanical strength, improving the durability of the bioenzyme / ZIF-8 / AgNPs / PLA composite fiber material. In addition, PLA has good biodegradability, which makes this invention advantageous in terms of environmental friendliness and biomedical applications. Attached Figure Description

[0056] Figure 1 This is a morphology diagram of the ZIF-8 nanoparticles obtained in Example 1 of the present invention.

[0057] Figure 2 This is a morphology diagram of the lysozyme / AgNPs / ZIF-8 / PLA composite fiber membrane material obtained in Example 1 of the present invention.

[0058] Figure 3 This is a morphology diagram of the HKUST-1 nanoparticles obtained in Example 2 of the present invention.

[0059] Figure 4 This is a morphology diagram of the polylactic acid (PLA) fiber membrane obtained in Comparative Example 1 of the present invention.

[0060] Figure 5 This is a morphology diagram of the AgNPs / PLA composite fiber membrane obtained in Comparative Example 4 of the present invention.

[0061] Figure 6 This is a comparison chart of the mechanical strength of different membrane materials. Detailed Implementation

[0062] The specific embodiments of the present invention will be further described below with reference to examples and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0063] Example 1

[0064] S1. Preparation of ZIF-8 nanoparticles: 2g benzimidazole, 4g zinc nitrate and 0.02g polyvinylpyrrolidone were added to 100ml dimethyl sulfoxide, mixed evenly, sonicated for 20min, and reacted at 80℃ and 400rpm for 10h to obtain ZIF-8 solution. After washing with methanol three times, centrifuged and dried at 50℃ for 8h, ZIF-8 nanoparticles were obtained.

[0065] S2. Preparation of AgNPs / ZIF-8 composite particles: 500 mg AgNPs particles and 500 mg ZIF-8 nanoparticles were added to 1000 ml methanol and stirred continuously at 300 rpm for 2 h at 30 °C. The resulting mixture was centrifuged at 8000 rpm for 5 min, and the solid precipitate was dried at 50 °C for 8 h to obtain AgNPs / ZIF-8 composite particles.

[0066] S3. Preparation of lysozyme / AgNPs / ZIF-8 composite particles: Weigh 500 mg of lysozyme and dissolve it in 1 L of phosphate buffer (pH 7.4) at 30℃ and 200 rpm for 2 hours to prepare an enzyme solution with a concentration of 0.5 mg / mL. Add 500 mg of AgNPs / ZIF-8 composite particles to the enzyme solution, stir at 40℃ and 200 rpm for 2 hours, sonicate for 5 minutes, centrifuge at 8000 rpm for 5 minutes, and dry the resulting solid precipitate at 50℃ for 8 hours to obtain lysozyme / AgNPs / ZIF-8 composite particles.

[0067] S4. Preparation of lysozyme / AgNPs / ZIF-8 / PLA composite fiber membrane material: 10 g of polylactic acid (PLA) was added to 90 g of dimethyl sulfoxide and mixed evenly to obtain a 10 wt% polylactic acid (PLA) solution; 0.1 g of lysozyme / AgNPs / ZIF-8 composite particles were added to 100 ml of the 10 wt% PLA solution and dispersed evenly to obtain a lysozyme / AgNPs / ZIF-8 / PLA spinning solution; the lysozyme / AgNPs / ZIF-8 / PLA composite fiber membrane material was prepared using electrospinning technology; the electrospinning conditions were a voltage of 15 kV, a flow rate of 3 ml / h, and a collection distance of 15 cm.

[0068] The scanning electron microscope image of the ZIF-8 nanoparticles prepared in step S1 of Example 1 is shown below. Figure 1 As shown, the scanning electron microscope image of the prepared lysozyme / AgNPs / ZIF-8 / PLA composite fiber membrane material is as follows. Figure 2 As shown.

[0069] Example 2

[0070] The difference between Example 2 and Example 1 is that in Example 2, the ZIF-8 nanoparticles in Example 1 are replaced with HKUST-1 nanoparticles. The remaining steps and parameters are the same as in Example 1. The preparation method of HKUST-1 nanoparticles is as follows:

[0071] 2g of benzimidazole, 4g of copper nitrate trihydrate and 0.02g of polyvinylpyrrolidone were added to 100ml of dimethyl sulfoxide, mixed evenly, sonicated for 20min and reacted at 80℃ and 400rpm for 10h to obtain HKUST-1 solution. After washing three times with methanol, centrifuged and dried at 50℃ for 8h, HKUST-1 nanoparticles were obtained.

[0072] The scanning electron microscope image of the HKUST-1 nanoparticles prepared in this embodiment is shown below. Figure 3 As shown.

[0073] Example 3

[0074] The difference between Example 3 and Example 1 is that in Example 3, 500mg of ZIF-8 nanoparticles in step S2 of Example 1 is replaced with 1000mg of ZIF-8 nanoparticles, while the remaining steps and parameters are the same as in Example 1; that is, in Example 3, the mass ratio of AgNPs particles to ZIF-8 nanoparticles in Example 1 is changed from 1:1 to 1:2.

[0075] Example 4

[0076] The difference between Example 4 and Example 1 is that in Example 4, the lysozyme in Example 1 is replaced with the same mass of catalase, while the remaining steps and parameters are the same as in Example 1.

[0077] Example 5

[0078] The difference between Example 5 and Example 1 is that in Example 5, the 0.5 mg / mL enzyme solution in step S3 is replaced with a 1.0 mg / mL solution (1000 mg of lysozyme is weighed and dissolved in 1 L of phosphate buffer (pH 7.4) at 30°C and stirred continuously at 200 rpm for 2 hours to prepare an enzyme solution with a concentration of 1.0 mg / mL). The remaining steps and parameters are the same as in Example 1.

[0079] The electrospinning process in Examples 2-5 is the same as that in Example 1. The differences are in the type of MOFs material, the ratio of AgNPs to MOFs, the type of biological enzyme and the concentration of biological enzyme. The differences in Examples 2-3 are shown in Table 1.

[0080] Table 1 Summary of differences in Examples 1-5

[0081] MOFs material types AgNPs and MOFs ratio Types of biological enzymes biological enzyme concentration Example 1 ZIF-8 1:1 Lysozyme 0.5 mg / mL Example 2 HKUST-1 1:1 Lysozyme 0.5 mg / mL Example 3 ZIF-8 1:2 Lysozyme 0.5 mg / mL Example 4 ZIF-8 1:1 catalase 0.5 mg / mL Example 5 ZIF-8 1:1 Lysozyme 1mg / mL

[0082] Comparative Example 1

[0083] The steps for preparing pure PLA fiber membrane material are as follows:

[0084] 10 g of polylactic acid (PLA) was added to 90 g of dimethyl sulfoxide and mixed evenly to obtain a 10 wt% PLA solution; electrospinning membrane preparation: PLA fiber membrane material was prepared using electrospinning technology. The electrospinning conditions were 15 kV voltage, 3 ml / h flow rate, and 15 cm collection distance.

[0085] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 directly spins polylactic acid (PLA) into a membrane using the polymer as the spinning agent, without adding MOF nanoparticles, AgNPs, or bioenzymes. The scanning electron microscope image of the PLA fiber membrane prepared in Comparative Example 1 is shown below. Figure 4 As shown.

[0086] Comparative Example 2

[0087] The steps for preparing the ZIF-8 / PLA composite fiber membrane material are as follows:

[0088] S1. Preparation of ZIF-8 nanoparticles: Same as in Example 1.

[0089] S2. Preparation of ZIF-8 / PLA composite fiber membrane material: 10 g of polylactic acid (PLA) was added to 90 g of dimethyl sulfoxide and mixed evenly to obtain a 10 wt% PLA solution; 50 mg of ZIF-8 particles were added to 100 ml of the 10 wt% PLA solution and dispersed evenly to obtain a ZIF-8 / PLA spinning solution. ZIF-8 / PLA composite fiber membrane material was prepared using electrospinning technology; the electrospinning conditions were: voltage 15 kV, flow rate 3 ml / h, and collection distance 15 cm.

[0090] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 only added ZIF-8 nanoparticles to the PLA fiber membrane, without adding AgNPs and bioenzymes.

[0091] Comparative Example 3

[0092] The steps for preparing the bio-enzyme / PLA composite fiber membrane material are as follows:

[0093] 10 g of polylactic acid (PLA) was added to 90 g of dimethyl sulfoxide and mixed evenly to obtain a 10 wt% PLA solution; 50 mg of lysozyme was added to 100 ml of 0 wt% PLA solution and dispersed evenly to obtain a lysozyme / PLA spinning solution; lysozyme / PLA composite fiber membrane material was prepared using electrospinning technology; the electrospinning conditions were a voltage of 15 kV, a flow rate of 3 ml / h, and a collection distance of 15 cm.

[0094] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 only added bio-enzymes to the PLA fiber membrane, without adding AgNPs and MOFs nanoparticles.

[0095] Comparative Example 4

[0096] The steps for preparing AgNPs / PLA composite fiber membrane materials are as follows:

[0097] 10 g of polylactic acid (PLA) was added to 90 g of dimethyl sulfoxide and mixed evenly to obtain a 10 wt% PLA solution; 50 mg of AgNPs was added to 100 mL of the 10 wt% PLA solution and dispersed evenly to obtain an AgNPs / PLA spinning solution; AgNPs / PLA composite fiber membrane material was prepared using electrospinning technology; the electrospinning conditions were 15 kV voltage, 3 mL / h flow rate, and 15 cm collection distance.

[0098] The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 only added AgNPs to the PLA fiber membrane, without adding bioenzymes or MOF nanoparticles. The scanning electron microscope image of the AgNPs / PLA fiber membrane material prepared in Comparative Example 4 is shown below. Figure 6 As shown.

[0099] Comparative Example 5

[0100] The steps for preparing lysozyme / AgNPs / PLA composite fiber membrane material are as follows:

[0101] S1. Preparation of lysozyme / AgNPs composite particles: Add 500 mg of nano-silver particles to a 0.5 mg / mL lysozyme solution (preparation method is the same as in Example 1), stir at 40°C and 200 rpm for 2 hours, sonicate for 5 min, centrifuge, centrifuge at 8000 rpm for 5 min, and dry the resulting solid precipitate at 50°C for 8 h to obtain lysozyme / AgNPs composite particles.

[0102] S2. Preparation of lysozyme / AgNPs / PLA composite fiber membrane material: 0.1g of lysozyme / AgNPs composite particles were added to 100mL of 10wt% PLA solution (preparation method as in Example 1), and dispersed evenly to obtain lysozyme / AgNPs / PLA spinning solution; lysozyme / AgNPs / PLA composite antibacterial membrane was prepared using electrospinning technology. The electrospinning conditions were set as follows: voltage 15kV, flow rate 3ml / h, and collection distance 15cm.

[0103] The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 only added AgNPs and bioenzymes to the PLA fiber membrane, without adding MOF nanoparticles.

[0104] Comparative Example 6

[0105] The steps for preparing the lysozyme / ZIF-8 / PLA composite fiber membrane material are as follows:

[0106] S1. Preparation of ZIF-8 nanoparticles: Same as in Example 1.

[0107] S2. Preparation of lysozyme / ZIF-8 / PLA composite particles: Add 500 mg of ZIF-8 nanoparticles to a 0.5 mg / mL lysozyme solution (preparation method as in Example 1), stir at 40°C and 200 rpm for 2 hours, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, and dry the solid precipitate at 50°C for 8 h to obtain lysozyme / ZIF-8 composite particles.

[0108] S3. Preparation of lysozyme / ZIF-8 / PLA composite fiber membrane material: Take 0.1g of lysozyme / ZIF-8 composite particles and add them to 100ml of 10wt% PLA solution (preparation method is the same as in Example 1), disperse evenly to obtain lysozyme / ZIF-8 / PLA spinning solution; prepare lysozyme / ZIF-8 / PLA composite fiber membrane material using electrospinning technology; the electrospinning conditions are voltage 15kV, flow rate 3ml / h, and collection distance 15cm.

[0109] The difference between Comparative Example 6 and Example 1 is that Comparative Example 6 only adds bio-enzymes and ZIF-8 to the PLA fiber membrane, without adding AgNPs particles.

[0110] Comparative Example 7

[0111] The preparation steps for AgNPs / ZIF-8 / PLA fiber membrane materials are as follows:

[0112] S1. Preparation of AgNPs / ZIF-8 composite particles: Same as in Example 1.

[0113] S2. Preparation of AgNPs / ZIF-8 / PLA composite fiber membrane material: 0.1g of AgNPs / ZIF-8 composite particles were added to a 10wt% PLA solution (preparation method is the same as in Example 1) to obtain AgNPs / ZIF-8 / PLA spinning solution; AgNPs / ZIF-8 / PLA composite fiber membrane material was prepared by electrospinning technology; the electrospinning conditions were 15kV voltage, 3ml / h flow rate, and 15cm collection distance.

[0114] The difference between Comparative Example 7 and Example 1 is that Comparative Example 7 only adds AgNPs and ZIF-8 to the PLA fiber membrane, without adding biological enzymes.

[0115] Comparative Example 8

[0116] The preparation method for lysozyme / FeNPs / ZIF-8 / PLA composite fiber membrane material is as follows:

[0117] S1. Preparation of ZIF-8 nanoparticles: Same as in Example 1.

[0118] S2. Preparation of FeNPs / ZIF-8 composite particles: 500 mg of FeNPs particles and 500 mg of ZIF-8 nanoparticles were added to 1000 ml of methanol and stirred continuously at 300 rpm for 2 h at 30 °C. The resulting mixture was centrifuged at 8000 rpm for 5 min, and the solid precipitate was dried at 50 °C for 8 h to obtain FeNPs / ZIF-8 composite particles.

[0119] S3. Preparation of lysozyme / FeNPs / ZIF-8 composite particles: Weigh 500 mg of lysozyme and dissolve it in 1 L of phosphate buffer (pH 7.4) at 30℃ and 200 rpm for 2 hours to prepare an enzyme solution with a concentration of 0.5 mg / mL. Add 500 mg of FeNPs / ZIF-8 composite particles to this solution, stir at 40℃ and 200 rpm for 2 hours, sonicate for 5 minutes, centrifuge at 8000 rpm for 5 minutes, and dry the resulting solid precipitate at 50℃ for 8 hours to obtain lysozyme / FeNPs / ZIF-8 particles.

[0120] S4. Preparation of lysozyme / FeNPs / ZIF-8 / PLA composite fiber membrane material: 10 g of polylactic acid (PLA) was added to 90 g of dimethyl sulfoxide and mixed evenly to obtain a 10 wt% polylactic acid (PLA) solution; 0.1 g of lysozyme / FeNPs / ZIF-8 composite particles were added to 100 ml of the 10 wt% PLA solution and dispersed evenly to obtain a lysozyme / FeNPs / ZIF-8 / PLA spinning solution; the lysozyme / FeNPs / ZIF-8 / PLA composite fiber membrane material was prepared using electrospinning technology; the electrospinning conditions were a voltage of 15 kV, a flow rate of 3 ml / h, and a collection distance of 15 cm.

[0121] The difference between Comparative Example 8 and Example 1 is that Comparative Example 8 adds antibacterial nano-metals FeNPs to the PLA fiber membrane.

[0122] Comparative Example 9

[0123] The steps for preparing lysozyme / AgNPs / ZIF-8 / PVA composite fiber membrane material are as follows:

[0124] S1. Preparation of lysozyme / AgNPs / ZIF-8 composite particles: Same as in Example 1.

[0125] S2. Preparation of lysozyme / AgNPs / ZIF-8 / PVA composite fiber membrane material: 10 g of polyvinyl alcohol (PVA) was added to 90 g of dimethyl sulfoxide and mixed evenly to obtain a 10 wt% PVA solution. 0.1 g of lysozyme / AgNPs / ZIF-8 composite particles were added to 100 ml of the 10 wt% PVA solution and dispersed evenly to obtain the lysozyme / AgNPs / ZIF-8 / PVA spinning solution. The lysozyme / AgNPs / ZIF-8 / PVA composite fiber membrane material was prepared using electrospinning technology; the electrospinning conditions were: voltage 15 kV, flow rate 3 ml / h, and collection distance 15 cm.

[0126] The difference between Comparative Example 9 and Example 1 is that the electrospun polymer used in Comparative Example 9 is polyvinyl alcohol (PVA) instead of polylactic acid (PLA).

[0127] Comparative Example 10

[0128] Preparation of lipase / AgNPs / ZIF-8 / PLA composite fiber membrane material:

[0129] S1. Preparation of AgNPs / ZIF-8 composite particles: Same as in Example 1.

[0130] S2. Preparation of lipase / AgNPs / ZIF-8 composite particles: Weigh 500 mg of lipase and dissolve it in 1 L of phosphate buffer (pH 7.4) at 30℃ and 200 rpm for 2 hours to prepare an enzyme solution with a concentration of 0.5 mg / mL. Add 500 mg of AgNPs / ZIF-8 composite particles to the enzyme solution, stir at 40℃ and 200 rpm for 2 hours, sonicate for 5 minutes, centrifuge at 8000 rpm for 5 minutes, and then dry the resulting solid at 50℃ for 8 hours to obtain the prepared lipase / silver nanoparticles / ZIF-8 particles.

[0131] S3. Preparation of lipase / AgNPs / ZIF-8 / PLA composite fiber membrane material: 0.1g of lipase / AgNPs / ZIF-8 composite particles were added to 100ml of 10wt% PLA solution (preparation method as in Example 1), and dispersed evenly to obtain lipase / AgNPs / ZIF-8 / PLA spinning solution. The lipase / AgNPs / ZIF-8 / PLA composite fiber membrane material was prepared using electrospinning technology; the electrospinning conditions were: voltage 15kV, flow rate 3ml / h, and collection distance 15cm.

[0132] The difference between Comparative Example 10 and Example 1 is that the biological enzyme used in Comparative Example 10 is lipase.

[0133] Test Example 1 Antibacterial Effect

[0134] Test subjects: different membrane materials prepared in Examples 1-5 and Comparative Examples 1-10.

[0135] Test strain: Escherichia coli (ATCC-8739).

[0136] Test conditions: The initial concentration of E. coli bacterial suspension was 3×10⁻⁶. 7 The concentration of bacteria was CFU / mL, the solution volume was 50 mL, and the membrane material dosage was 0.4 g / L. The bacterial concentrations before and after the experiment were obtained using the plate count method, and the results were compared to obtain the final test results.

[0137] Table 2. Test results of different membrane materials in removing E. coli

[0138]

[0139] Table 2 shows the experimental results of different membrane materials in removing *E. coli*. It can be seen that under the same test conditions, Examples 1, 2, 3, 4, 5, Comparative Example 5, and Comparative Example 9 achieved a sterilization rate of up to 100% within 4 hours. Example 1 showed a significantly higher sterilization effect than Comparative Example 1 and Comparative Example 2 because Example 1 did not contain the antibacterial material nano-silver and bio-enzyme. Example 1 showed a higher sterilization effect than Comparative Example 3, Comparative Example 4, Comparative Example 6, and Comparative Example 7, indicating that nano-silver and bio-enzyme played a synergistic antibacterial role. Example 1 showed a higher sterilization effect than Example 8, indicating that under the catalytic action of lysozyme, the sterilization effect of nano-silver was much higher than that of nano-iron. Examples 1-5 showed a higher sterilization effect than Example 10, indicating that the synergistic sterilization effect of lysozyme, catalase, and nano-silver was much higher than the synergistic sterilization effect of lipase and nano-silver. Comparing Examples 1, 5, and 9, it can be seen that although Examples 1, 5, and 9 achieved a sterilization rate of up to 100% within 4 hours, Example 1 had a higher sterilization efficiency than Examples 5 and 9. This indicates that the type of MOF nanoparticles and polymers added to the composite fiber membrane material affects the sterilization effect. Adding MOF nanoparticles to the composite fiber membrane material, and using polylactic acid as the base material, is more conducive to enhancing the sterilization effect.

[0140] Test Example 2: Heavy Metal Adsorption Effect

[0141] Test subjects: Composite fiber membrane materials prepared in Examples 1-5 and Comparative Examples 1-10.

[0142] Tested pollutants: Cadmium nitrate (Cd(NO3)2), Lead nitrate (Pb(NO3)2)

[0143] Test conditions: The volume of the heavy metal solution was 1000 ml. The initial concentrations of cadmium nitrate (Cd(NO3)2) and lead nitrate (Pb(NO3)2) in the heavy metal solution were both 10 mg / L. The dosage of the composite fiber membrane material was 20 mg / L. The membrane material was placed in the heavy metal solution and reacted at 35℃ and 300 rpm for 6 hours. After that, the membrane material was removed, and the concentration of Cd in the solution after 6 hours of reaction was determined by atomic absorption spectrometry. 2+ Pb 2+ Ion concentration, calculation of Cd 2+ Pb 2+ The adsorption rate.

[0144] Table 3 Adsorption capacity of different membrane materials for heavy metals

[0145]

[0146]

[0147] The results of the heavy metal adsorption experiment are shown in Table 3. It can be seen that under the same test conditions, Example 1 showed a significantly higher removal rate of cadmium (Cd) and lead (Pb) in water than Comparative Examples 1-5, indicating that the membrane material must be loaded with MOFs to possess catalytic performance. Example 1 showed a higher removal rate than Example 2, indicating that among the MOFs, ZIF-8 had a higher adsorption performance for heavy metals than HKUST-1. Example 1 showed a higher removal rate than Example 9 because, although the amount of ZIF-8 applied was the same, the PVA substrate in Comparative Example 9 dissolved in water, causing some ZIF-8 particles to detach, leaving the adsorbed heavy metals in the water. The heavy metal adsorption effect of Comparative Example 10 was also relatively high, but still lower than that of Example 1, indicating that in this invention, there is an interaction between PLA and MOFs nanoparticles, biological enzymes, and nano-silver, which improves the adsorption effect of the composite fiber membrane.

[0148] Test Example 3 Mechanical Strength

[0149] Test subjects: Composite fiber membrane materials prepared in Examples 1-5 and Comparative Examples 1-10.

[0150] Test conditions: The electrospun film was cut into 10cm long and wide specimens using a precision cutting tool and placed flat between the clamps of the testing machine. The testing machine was set to stretch the specimens at a constant rate of 100mm / min, and the tensile force and elongation of the specimens were recorded simultaneously during the process until the specimens broke. The maximum tensile force and the total elongation at break were recorded. Tensile strength is the maximum tensile force divided by the original cross-sectional area of ​​the specimen (width multiplied by thickness). Elongation at break is the ratio of the elongation at break to the original length, expressed as a percentage.

[0151] The mechanical strength test results of different membrane materials are shown in Figure 6It can be seen that under the same test conditions, the tensile strength and elongation at break of Example 1 are higher than those of Comparative Examples 1, 2, 3, 4, 5, and 6, indicating that higher mechanical strength can only be achieved by loading MOFs and nano-silver materials into the membrane material. The tensile strength of Example 3 is higher than that of Example 1, indicating that the more MOFs loaded, the higher the mechanical strength of the membrane. Example 1 is higher than Example 2 and Comparative Example 8, indicating that ZIF-8 enhances the mechanical strength of the membrane more than HKUST-1 and FeNPs. Example 1 is higher than Comparative Examples 7 and 10, indicating that the introduction of biological enzymes helps to enhance the mechanical strength of the membrane, and the enhancing effect of lysozyme is higher than that of lipase. The tensile strength and elongation at break of Example 1 are higher than those of Comparative Example 9, indicating that in the electrospinning substrate, PLA enhances the mechanical properties of the membrane more than PVA.

Claims

1. The application of a bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material in water treatment, characterized in that, It is used to adsorb heavy metals in polluted water and kill bacteria, viruses and parasites in the water; the preparation method of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material includes the following steps: (1) Add AgNPs particles and MOFs nanoparticles to an organic solvent, stir and react, and dry the mixture to obtain AgNPs / MOFs composite particles; (2) The AgNPs / MOFs composite particles were added to the bio-enzyme solution, stirred, centrifuged, and sonicated to obtain bio-enzyme / AgNPs / MOFs composite particles; (3) The bio-enzyme / AgNPs / MOFs composite particles are added to a polylactic acid solution and dispersed evenly to obtain a spinning solution. The spinning solution is electrospun to obtain a bio-enzyme / AgNPs / MOFs / PLA composite fiber membrane material.

2. The application of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material according to claim 1 in water treatment, characterized in that, The MOF nanoparticles in step (1) include one or more of ZIF-8 nanoparticles, ZIF-67 nanoparticles, and HKUST-1 nanoparticles; the mass ratio of the AgNPs particles to the MOF nanoparticles is (1-2):(1-4).

3. The application of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material according to claim 1 in water treatment, characterized in that, The organic solvent in step (1) is one or more of ethanol, methanol, dimethyl sulfoxide, and N,N-dimethylformamide; the temperature of the stirring reaction is 25-35℃, and the stirring reaction time is 1-3h.

4. The application of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material according to claim 1 in water treatment, characterized in that, The biological enzymes mentioned in step (2) include one or more of lysozyme, catalase, ursylase, and anti-streptococcal enzyme.

5. The application of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material according to claim 1 in water treatment, characterized in that, In step (2), the concentration of the bioenzyme in the bioenzyme solution is 0.1-2 mg / mL; the solvent of the bioenzyme solution is phosphate buffer solution with a pH of 6.8-7.8; the mass ratio of the AgNPs / MOFs composite particles to the bioenzyme solution is (300-1500) mg: 1L.

6. The application of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material according to claim 1 in water treatment, characterized in that, The stirring temperature in step (2) is 30-50℃, and the stirring time is 1-4h.

7. The application of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material according to claim 1 in water treatment, characterized in that, The mass concentration of the polylactic acid solution in step (3) is 8-12%; the solvent of the polylactic acid solution is one or more of ethyl acetate, dimethyl sulfoxide, and tetrahydrofuran; the mass ratio of the bioenzyme / AgNPs / ZIF-8 composite particles to the polylactic acid solution is 1:(100-300).

8. The application of the bio-enzyme / MOFs / AgNPs / PLA composite fiber membrane material according to claim 1 in water treatment, characterized in that, The conditions for electrospinning in step (3) are: voltage 12-18 kV, flow rate 2-4 mL / h, and collection distance 12-18 cm.

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