Filter membranes and their preparation methods, filter elements and applications

Abstract

This invention discloses a filter membrane, its preparation method, filter element, and application. The preparation method of the filter membrane includes the following steps: (1) preparing a membrane from a casting solution to obtain an initial filter membrane. The casting solution includes the following components: 13-25% membrane substrate material, 10-20% pore-forming agent, 0.5-2% silver acetylacetone, and an organic solvent, where % refers to the mass percentage of each component relative to the mass of the casting solution; (2) contacting the initial filter membrane with an aqueous solution to attach amine monomers, and then contacting it with an oil solution for interfacial polymerization to obtain the filter membrane; wherein the aqueous solution includes amine monomers, and the oil solution includes acyl chloride monomers containing at least two acyl chloride groups. The filter membrane prepared by this invention has better antibacterial properties, and the antibacterial particles can be better fixed in the membrane, are less prone to loss, and have a longer-lasting antibacterial effect. The generation of antibacterial particles can also promote interfacial polymerization, so that no new acid-binding agent needs to be added to the system.

Description

Technical Field

[0001] This invention relates to a filter membrane, its preparation method, filter element, and application. Background Technology

[0002] In water purifier systems, antibacterial technology is commonly used to address biological contamination (bacterial growth forming biofilms). Although the raw water may contain few bacteria, they can easily proliferate, affecting the safety of the water purifier. Therefore, antibacterial treatment of the water purifier is crucial. Nanofiltration / reverse osmosis is the core separation component in the entire water purifier system. Using nanofiltration / reverse osmosis as a dividing point, the entire water system can be divided into two parts: the product water side and the raw water side. On the product water side, an antibacterial solution consisting of a post-filter carbon rod and ultraviolet light sterilization is used to ensure that the water flowing from the faucet is clean, meaning the user is drinking healthy water. On the raw water side of the nanofiltration / reverse osmosis membrane, besides the residual chlorine in the tap water, there are no other antibacterial solutions. The result is that when tap water passes through the pre-treatment filter, the residual chlorine in the water is adsorbed. Without residual chlorine protection, the water in contact with the nanofiltration / reverse osmosis filter cartridge is prone to bacterial growth and biofilm formation, which in turn affects the flux and selectivity of the nanofiltration / reverse osmosis filter cartridge and reduces its service life.

[0003] Nanofiltration / reverse osmosis filter cartridges consist of four parts: a separator, a nanofiltration / reverse osmosis membrane, a flow guide cloth, and a central tube. The separator and nanofiltration / reverse osmosis membrane are located on the raw water side, where bacteria easily proliferate and require antibacterial treatment. As the core separation component, the nanofiltration membrane shows significant antibacterial properties after modification, making it an excellent solution for eliminating contamination on the raw water side of nanofiltration / reverse osmosis filter cartridges.

[0004] In existing technologies, nanofiltration / reverse osmosis membranes with antibacterial properties are typically prepared by adding nanoparticles with antibacterial properties during the interfacial polymerization process. However, these nanoparticles are easily lost during the use of the filter cartridge, causing secondary pollution. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the defect of easy loss of antibacterial particles in existing nanofiltration / reverse osmosis membranes with antibacterial properties, and to provide a filter membrane, its preparation method, filter element, and application. The filter membrane of this invention has less risk of loss of antibacterial particles, a more lasting antibacterial effect, and a simple preparation method.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] The present invention also provides a method for preparing a filter membrane, which includes the following steps:

[0008] (1) The casting solution is used to prepare a membrane to obtain an initial filter membrane. The casting solution includes the following components: 13-25% membrane bulk material, 10-20% pore-forming agent, 0.5-2% silver acetylacetone, and organic solvent. The percentage refers to the mass percentage of each component in the casting solution.

[0009] (2) The initial filter membrane is contacted with an aqueous solution to attach amine monomers, and then contacted with an oil solution to carry out an interfacial polymerization reaction to obtain the filter membrane; wherein the aqueous solution includes amine monomers and the oil solution includes acyl chloride monomers containing at least two acyl chloride groups.

[0010] In this invention, the method of preparing the film can be a conventional film-forming method in the art, such as coating or spinning the casting solution.

[0011] In this invention, the filter membrane can be a flat sheet filter membrane or a hollow fiber filter membrane.

[0012] In step (1), when the structure type of the filter membrane is a flat sheet filter membrane, the method of preparing the membrane can be a scraped membrane; when the structure type of the filter membrane is a hollow fiber filter membrane, the method of preparing the membrane can be spinning.

[0013] During the film formation process, a coagulation bath can be used. The medium of the coagulation bath is generally water, and the temperature of the coagulation bath can be 20-60℃.

[0014] In this invention, preferably, in step (1), the membrane host material is selected from one of polysulfone, polyethersulfone, polypropylene, polyvinylidene fluoride, polyvinyl chloride and polyimide.

[0015] In this invention, preferably, the number-average molecular weight of the membrane substrate material is 5w-20w.

[0016] In this invention, preferably, the pore-forming agent comprises a mixture of polyvinylpyrrolidone and polyethylene glycol.

[0017] More preferably, the pore-forming agent comprises 5-10% polyvinylpyrrolidone and 5-10% polyethylene glycol, wherein % refers to the mass percentage of the component relative to the mass of the casting solution.

[0018] Preferably, the polyvinylpyrrolidone is PVPK15.

[0019] Preferably, the polyethylene glycol is PEG600.

[0020] In this invention, in step (1), the organic solvent can be a conventional organic solvent in the art, such as N,N-dimethylformamide or N,N-dimethylacetamide.

[0021] In this invention, preferably, in step (1), the amount of the membrane substrate material is 18-20%, for example 19%, where % refers to the mass percentage of the component relative to the mass of the casting solution.

[0022] In this invention, preferably, in step (1), the amount of polyvinylpyrrolidone used is 6-8%, where % refers to the mass percentage of the component relative to the mass of the casting solution.

[0023] In this invention, preferably, in step (1), the amount of polyethylene glycol used is 6-8%, for example 7%, where % refers to the mass percentage of the component relative to the mass of the casting solution.

[0024] In this invention, preferably, in step (1), the amount of silver acetylacetone used is 0.8%, 1% or 1.2%, where % refers to the mass percentage of the component relative to the mass of the casting solution.

[0025] In this invention, preferably, the amount of organic solvent used is such that the mass of the casting solution is replenished to 100%.

[0026] In this invention, preferably, in step (2), the amine monomer is an amine monomer containing at least two amino groups, more preferably piperazine and / or m-phenylenediamine.

[0027] In this invention, preferably, in step (2), the mass concentration of the amine monomer in the aqueous solution is 0.1-1.5 wt%, for example 0.2 wt%, 0.4 wt%, 0.5 wt%, and 1.2 wt%, wherein wt% refers to the mass percentage of the amine monomer in the aqueous solution.

[0028] In this invention, the solvent of the aqueous solution is water.

[0029] In this invention, preferably, in step (2), the acyl chloride monomer is pyromellitic trimethylolpropionate chloride.

[0030] In this invention, preferably, in step (2), the mass concentration of the acyl chloride monomer in the oil phase solution is 0.2-0.5 wt%, for example 0.3 wt% or 0.4 wt%, where wt% refers to the mass percentage of the oil phase monomer to the mass of the oil phase solution.

[0031] In this invention, preferably, in step (2), the solvent of the oil phase solution is one or more of n-hexane, isoalkanes L, G, and M.

[0032] In this invention, preferably, in step (2), the contact can be made by immersion, for example, immersing the initial filter membrane in an aqueous solution or an oil solution.

[0033] The immersion is not subject to temperature requirements; for example, it can be carried out at room temperature, such as 20±5℃.

[0034] In this invention, preferably, in step (2), the initial filter membrane is in contact with the aqueous solution for a time sufficient to allow the amine monomers to fully adhere to the membrane, preferably 4-6 minutes, for example 5 minutes.

[0035] In this invention, preferably, in step (2), the solvent in the aqueous solution in the initial filter membrane is completely evaporated after contact with the aqueous solution and before contact with the oil solution.

[0036] In this invention, preferably, in step (2), the initial filter membrane is in contact with the oil phase solution for more than 30 seconds, for example, 30 seconds.

[0037] In this invention, preferably, in step (2), after the initial filter membrane comes into contact with the oil phase solution, the solvent in the oil phase solution in the initial filter membrane is completely evaporated. For example, the filter membrane is vigorously shaken to evaporate the solvent.

[0038] In this invention, preferably, after step (2), a post-processing step is also included.

[0039] The post-processing method can be a conventional method in the art, such as drying.

[0040] The post-processing temperature is preferably 60-100℃, for example 70, 80 or 90℃.

[0041] The post-treatment time is preferably sufficient to allow the reaction to proceed fully, more preferably 1-30 min, for example 2, 5, 10 or 20 min.

[0042] The present invention also provides a filter membrane prepared by the aforementioned filter membrane preparation method.

[0043] The present invention also provides a filter membrane comprising an ultrafiltration layer and a separation layer, wherein the ultrafiltration layer comprises a membrane substrate material, the separation layer comprises polyamide, the thickness of the ultrafiltration layer is 50-1000 μm, the thickness of the separation layer is 1-10 nm, and silver chloride is distributed in the ultrafiltration layer and the separation layer.

[0044] In this invention, acetylacetone is retained in the ultrafiltration membrane during the interfacial polymerization process.

[0045] In this invention, the type of filter membrane may be a nanofiltration membrane or a reverse osmosis membrane.

[0046] The filter membrane can be a flat sheet filter membrane or a hollow fiber filter membrane.

[0047] When the filter membrane is a flat sheet filter membrane, preferably, the filter membrane further includes a support layer, wherein the ultrafiltration layer is located between the support layer and the separation layer.

[0048] Preferably, the support layer and the ultrafiltration layer have the same composition and thickness.

[0049] When the filter membrane is a flat sheet filter membrane, preferably, the thickness of the ultrafiltration layer is about 50-300 μm.

[0050] When the filter membrane is a hollow fiber membrane, preferably, the thickness of the ultrafiltration layer is about 400-1000 μm.

[0051] The filter membrane can be in the shape of a sheet or a filament, i.e., a sheet or a filament.

[0052] The present invention also provides a filter element comprising the filter membrane as described above.

[0053] The present invention also provides an application of the aforementioned filter membrane or filter element in a water purification device.

[0054] In this invention, the water purification device is, for example, a water purifier.

[0055] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0056] The reagents and raw materials used in this invention are all commercially available.

[0057] The positive and progressive effects of this invention are as follows:

[0058] 1. The silver acetylacetone used in this invention is insoluble in water, so more of it can remain on the membrane during the casting process, providing more reaction sites for subsequent reactions. After the reaction, more antibacterial particles are generated, resulting in stronger antibacterial performance of the prepared filter membrane.

[0059] 2. In this invention, silver acetylacetone reacts with hydrochloric acid generated during interfacial polymerization to produce silver chloride. This reaction occurs simultaneously with the interfacial polymerization reaction, which is more conducive to the fixation of silver chloride particles in the membrane, making them less prone to loss and resulting in a longer-lasting antibacterial effect. If silver chloride is added directly during the interfacial polymerization process, it is easy for the silver chloride to detach, affecting the antibacterial effect, and there is a risk of slow release during use.

[0060] 3. In this invention, the antibacterial particle reactant is a byproduct of the interfacial polymerization reaction. Therefore, the generation of antibacterial particles can also promote the interfacial polymerization reaction, eliminating the need to add new acid-binding agents to the system. The preparation method is simple. Detailed Implementation

[0061] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0062] In the following examples, the number-average molecular weight of the membrane substrate material is 5w-20w.

[0063] During the film-forming process by scraping or spinning, the medium in the coagulation bath is water, and the temperature of the coagulation bath is 20-60℃.

[0064] Example 1

[0065] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6 wt% polyethylene glycol (PEG600), 1 wt% silver acetylacetone, and the remainder is N,N-dimethylformamide, an organic solvent. After the casting solution is homogeneous and stable, perform membrane scraping to prepare a flat sheet ultrafiltration membrane;

[0066] (2) An interfacial polymerization reaction was carried out on a flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a piperazine concentration of 0.4 wt% for 5 min. The membrane was removed and, when the aqueous phase was basically completely evaporated, the membrane was placed in a hexane solution with a pyromellitic chloride concentration of 0.3 wt% for 30 s. The membrane was then removed and vigorously shaken to make the oil phase evaporate quickly. The membrane was placed in an oven at 60°C and post-treated for 10 min to obtain a flat sheet nanofiltration membrane with antibacterial properties.

[0067] (3) The prepared flat nanofiltration membrane was subjected to flux and retention tests. A flat nanofiltration membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 11 LMH and the magnesium sulfate retention rate was 95%.

[0068] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.5% and 99.7%, respectively. Simulating the use of nanofiltration membrane in a water purifier, after 2L of water was filtered through the nanofiltration membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.1% and 99.5%, respectively, which were basically no different from the antibacterial rates before use.

[0069] Example 2

[0070] (1) Prepare the casting solution with the following formula: 20wt% polysulfone, 8wt% polyvinylpyrrolidone (PVPK15), 7wt% polyethylene glycol (PEG600), 0.8wt% silver acetylacetone, and the remainder is the organic solvent N,N-dimethylacetamide. After the casting solution is homogeneous and stable, spin the fibers to prepare a hollow fiber ultrafiltration membrane.

[0071] (2) Interfacial polymerization reaction was carried out on the hollow fiber ultrafiltration membrane. The membrane fiber was immersed in an aqueous solution with a concentration of 0.5 wt% m-phenylenediamine for 5 min. The membrane fiber was removed and the aqueous phase was basically completely evaporated. The membrane fiber was then placed in a hexane solution with a concentration of 0.2 wt% trimesoyl chloride for 30 s. The membrane fiber was then removed and vigorously shaken to make the oil phase evaporate quickly. The membrane fiber was placed in an oven at 70°C and post-treated for 5 min to obtain a hollow fiber reverse osmosis membrane with antibacterial properties.

[0072] (3) The hollow fiber reverse osmosis membrane was tested for flux and rejection. The hollow fiber reverse osmosis membrane was placed in the test fixture. Its water flux was 5 LMH and the sodium chloride rejection rate was 99.9%.

[0073] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.5% and 99.9%, respectively. Simulating the use of the reverse osmosis membrane in a water purifier, after 2L of water was filtered through the reverse osmosis membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.0% and 98.5%, respectively, which were basically no different from the antibacterial rates before use.

[0074] Example 3

[0075] (1) Prepare the casting solution with the following formula: 20wt% polysulfone, 56wt% polyvinylpyrrolidone (PVPK1), 8wt% polyethylene glycol (PEG600), 2wt% silver acetylacetone, and the remainder is N,N-dimethylformamide, an organic solvent. After the casting solution is homogeneous and stable, perform membrane scraping to prepare a flat sheet ultrafiltration membrane;

[0076] (2) An interfacial polymerization reaction was carried out on the flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a concentration of 0.2 wt% m-phenylenediamine for 5 min. The membrane was removed and the aqueous phase was allowed to evaporate completely. The membrane was then placed in a hexane solution with a concentration of 0.2 wt% trimesoyl chloride for 30 s. The membrane was then removed and vigorously shaken to allow the oil phase to evaporate quickly. The membrane was then placed in an oven at 90°C and post-treated for 2 min to obtain a flat sheet reverse osmosis membrane with antibacterial properties.

[0077] (3) The prepared flat reverse osmosis membrane was subjected to flux and rejection tests. A flat reverse osmosis membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 6 LMH and the sodium chloride rejection rate was 99.9%.

[0078] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.6% and 99.5%, respectively. Simulating the use of the reverse osmosis membrane in a water purifier, after 2L of water was filtered through the reverse osmosis membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.3% and 99.3%, respectively, which were basically no different from the antibacterial rates before use.

[0079] Example 4

[0080] (1) Prepare the casting solution with the following formula: 18wt% polysulfone, 158wt% polyvinylpyrrolidone (PVPK), 6wt% polyethylene glycol (PEG600), 0.5wt% silver acetylacetone, and the remainder is N,N-dimethylacetamide, an organic solvent. After the casting solution is homogeneous and stable, spin the fibers to prepare a hollow fiber ultrafiltration membrane.

[0081] (2) Interfacial polymerization reaction was carried out on the hollow fiber ultrafiltration membrane. The membrane fiber was immersed in an aqueous solution with a piperazine concentration of 1.2wt% for 5 minutes. The membrane fiber was removed and the aqueous phase was basically completely evaporated. The membrane fiber was then placed in a n-hexane solution with a pyromellitic trimethylol chloride concentration of 0.4wt% for 30 seconds. The membrane fiber was then removed and vigorously shaken to make the oil phase evaporate quickly. The membrane fiber was then placed in an oven at 80℃ and post-treated for 20 minutes to obtain a hollow fiber nanofiltration membrane with antibacterial properties.

[0082] (3) The hollow fiber nanofiltration membrane was tested for flux and retention. The hollow fiber nanofiltration membrane was placed in the test fixture. Its water flux was 9 LMH and the magnesium sulfate retention rate was 97%.

[0083] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.4% and 99.3%, respectively. Simulating the use of the reverse osmosis membrane in a water purifier, after 2L of water was filtered through the reverse osmosis membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 99.0% and 99.1%, respectively, which were basically no different from the antibacterial rates before use.

[0084] Example 5

[0085] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6 wt% polyethylene glycol (PEG600), 1 wt% silver acetylacetone, and the remainder is N,N-dimethylformamide, an organic solvent. After the casting solution is homogeneous and stable, perform membrane scraping to prepare a flat sheet ultrafiltration membrane;

[0086] (2) An interfacial polymerization reaction was carried out on a flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a piperazine concentration of 0.4 wt% for 5 min. The membrane was removed and, when the aqueous phase was basically completely evaporated, the membrane was placed in a n-hexane solution with a pyromellitic chloride concentration of 0.3 wt% for 20 s. The membrane was then removed and vigorously shaken to make the oil phase evaporate quickly. The membrane was placed in an oven at 60°C and post-treated for 10 min to obtain a flat sheet nanofiltration membrane with antibacterial properties.

[0087] (3) The prepared flat nanofiltration membrane was subjected to flux and retention tests. A flat nanofiltration membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 15 LMH and the magnesium sulfate retention rate was 89%.

[0088] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 88.1% and 82.6%, respectively. Simulating the use of nanofiltration membrane in a water purifier, after 2L of water was filtered through the nanofiltration membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 43.5% and 37.8%, respectively.

[0089] Example 6

[0090] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6 wt% polyethylene glycol (PEG600), 1 wt% silver acetylacetone, and the remainder is N,N-dimethylformamide, an organic solvent. After the casting solution is homogeneous and stable, perform membrane scraping to prepare a flat sheet ultrafiltration membrane;

[0091] (2) An interfacial polymerization reaction was carried out on a flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a piperazine concentration of 0.4 wt% for 5 min. The membrane was removed and the aqueous phase was allowed to evaporate completely. The membrane was then placed in a hexane solution with a pyromellitic chloride concentration of 0.3 wt% for 20 s. The membrane was then removed and vigorously shaken to allow the oil phase to evaporate quickly. The membrane was then placed in an oven at 60 ℃ and post-treated for 30 s to obtain a flat sheet nanofiltration membrane with antibacterial properties.

[0092] (3) The prepared flat nanofiltration membrane was subjected to flux and rejection tests. A flat nanofiltration membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 20 LMH and the magnesium sulfate rejection rate was 87%.

[0093] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 75.1% and 84.3%, respectively. Simulating the use of nanofiltration membrane in a water purifier, after 2L of water was filtered through the nanofiltration membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 39.5% and 45.7%, respectively.

[0094] Comparative Example 1

[0095] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6 wt% polyethylene glycol (PEG600), 1 wt% nano silver, and the remainder is N,N-dimethylformamide, an organic solvent. After the casting solution is homogeneous and stable, perform membrane scraping to prepare a flat sheet ultrafiltration membrane;

[0096] (2) An interfacial polymerization reaction was carried out on a flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a piperazine concentration of 0.4 wt% for 5 min. The membrane was removed and, when the aqueous phase was basically completely evaporated, the membrane was placed in a hexane solution with a pyromellitic chloride concentration of 0.3 wt% for 30 s. The membrane was then removed and vigorously shaken to make the oil phase evaporate quickly. The membrane was placed in an oven at 60°C and post-treated for 10 min to obtain a flat sheet nanofiltration membrane with antibacterial properties.

[0097] (3) The prepared flat nanofiltration membrane was subjected to flux and retention tests. A flat nanofiltration membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 13 LMH and the magnesium sulfate retention rate was 92%.

[0098] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 78.5% and 88.3%, respectively. Simulating the use of nanofiltration membrane in a water purifier, after 2L of water was filtered through the nanofiltration membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 23.1% and 27.5%, respectively, showing a significant decrease in antibacterial rate.

[0099] Comparative Example 2

[0100] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6.9 wt% polyethylene glycol (PEG600), 0.1 wt% nano silver, and the remainder is N,N-dimethylformamide, an organic solvent. After the casting solution is homogeneous and stable, perform membrane scraping to prepare a flat sheet ultrafiltration membrane;

[0101] (2) An interfacial polymerization reaction was carried out on a flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a piperazine concentration of 0.4 wt% for 5 min. The membrane was removed and, when the aqueous phase was basically completely evaporated, the membrane was placed in a hexane solution with a pyromellitic chloride concentration of 0.3 wt% for 30 s. The membrane was then removed and vigorously shaken to make the oil phase evaporate quickly. The membrane was placed in an oven at 60°C and post-treated for 10 min to obtain a flat sheet nanofiltration membrane with antibacterial properties.

[0102] (3) The prepared flat nanofiltration membrane was subjected to flux and retention tests. A flat nanofiltration membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 13 LMH and the magnesium sulfate retention rate was 92%.

[0103] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 35.7% and 43.9%, respectively. Simulating the use of nanofiltration membrane in a water purifier, after 2L of water was filtered through the nanofiltration membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 19.6% and 24.5%, respectively, showing a significant decrease in antibacterial rate.

[0104] Comparative Example 3

[0105] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6 wt% polyethylene glycol (PEG600), and the remainder is N,N-dimethylformamide, an organic solvent; after the casting solution is homogeneous and stable, the membrane is scraped to prepare a flat sheet ultrafiltration membrane.

[0106] (2) An interfacial polymerization reaction was carried out on a flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a piperazine concentration of 0.4 wt% for 5 min. The membrane was removed and, when the aqueous phase was basically completely evaporated, the membrane was placed in a hexane solution with a pyromellitic chloride concentration of 0.3 wt% for 30 s. The membrane was then removed and vigorously shaken to make the oil phase evaporate quickly. The membrane was placed in an oven at 60°C and post-treated for 10 min to obtain a flat sheet nanofiltration membrane with antibacterial properties.

[0107] (3) The prepared flat nanofiltration membrane was subjected to flux and retention tests. A flat nanofiltration membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 11 LMH and the magnesium sulfate retention rate was 96%.

[0108] (4) The antibacterial performance of the antibacterial filter membrane was tested in accordance with GB21551.2-2010, "Special requirements for antibacterial materials with antibacterial, sterilization and purification functions for household and similar electrical appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 12.3% and 6.7%, respectively.

[0109] Comparative Example 4

[0110] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6 wt% polyethylene glycol (PEG600), 1 wt% silver nitrate, and the remainder is the organic solvent N,N-dimethylformamide. The casting solution cannot form a homogeneous and stable solution, making it unsuitable for film scraping or spinning.

[0111] Comparative Example 5

[0112] (1) Prepare the casting solution with the following formula: 19% wt% polysulfone, 156 wt% polyvinylpyrrolidone (PVPK), 6 wt% polyethylene glycol (PEG600), and the remainder is N,N-dimethylformamide, an organic solvent. After the casting solution is homogeneous and stable, perform membrane scraping to prepare a flat sheet ultrafiltration membrane;

[0113] (2) An interfacial polymerization reaction was carried out on a flat sheet ultrafiltration membrane. The membrane was immersed in an aqueous solution with a piperazine concentration of 0.4 wt% and a silver nitrate concentration of 1% for 5 min. The membrane was removed and the aqueous phase was allowed to evaporate completely. The membrane was then placed in a hexane solution with a pyromellitic chloride concentration of 0.3 wt% for 30 s. The membrane was then removed and vigorously shaken to allow the oil phase to evaporate quickly. The membrane was then placed in an oven at 60°C and post-treated for 10 min to obtain a flat sheet nanofiltration membrane with antibacterial properties.

[0114] (3) The prepared flat nanofiltration membrane was subjected to flux and retention tests. A flat nanofiltration membrane with a diameter of 53 mm was placed in the test fixture. Its water flux was 11 LMH and the magnesium sulfate retention rate was 95%.

[0115] (4) The antibacterial performance of the antibacterial filter membrane was tested according to GB21551.2-2010, "Special Requirements for Antibacterial Materials with Antibacterial, Sterilizing and Purifying Functions in Household and Similar Electrical Appliances". The antibacterial rates against Escherichia coli and Staphylococcus aureus were 76.9% and 80.7%, respectively. Simulating the use of nanofiltration membrane in a water purifier, after 2L of water was filtered through the nanofiltration membrane, the antibacterial rates against Escherichia coli and Staphylococcus aureus were 32.5% and 35.5%, respectively, showing a significant decrease in antibacterial rate.

[0116] The results showed that, compared with other examples, the antibacterial durability was affected when the oil phase immersion time and post-treatment heating time were too short. Comparative Examples 1-5 showed that when silver acetylacetone was not present, or when silver acetylacetone was replaced with nano-silver or silver nitrate, or when antibacterial particles were added directly during the interfacial polymerization stage, not only did the antibacterial activity decrease, but the antibacterial durability of the present invention could not be achieved.

[0117] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for preparing a filter membrane, characterized in that, It includes the following steps: (1) The casting solution is used to prepare a membrane to obtain an initial filter membrane. The casting solution includes the following components: 13-25% membrane substrate material, 10-20% pore-forming agent, 0.5-2% silver acetylacetone, and organic solvent. The percentage refers to the mass percentage of each component in the casting solution. (2) The initial filter membrane is contacted with an aqueous solution to attach amine monomers, and then contacted with an oil solution to carry out an interfacial polymerization reaction to obtain the filter membrane; wherein the aqueous solution includes amine monomers and the oil solution includes acyl chloride monomers containing at least two acyl chloride groups.

2. The method for preparing the filter membrane as described in claim 1, characterized in that, The type of filter membrane is nanofiltration membrane or reverse osmosis membrane; And / or, the filter membrane is a flat sheet filter membrane or a hollow fiber filter membrane; In step (1), when the structure type of the filter membrane is a flat sheet filter membrane, the membrane preparation method is a scraped membrane; when the structure type of the filter membrane is a hollow fiber filter membrane, the membrane preparation method is spinning. And / or, in step (1), the film-forming process is carried out in a coagulation bath, the temperature of which is 20-60℃; the medium of which is water. And / or, in step (1), the membrane host material is selected from one of polysulfone, polyethersulfone, polypropylene, polyvinylidene fluoride, polyvinyl chloride and polyimide; And / or, in step (1), the number-average molecular weight of the membrane substrate material is 5w-20w; And / or, in step (1), the organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide; And / or, the pore-forming agent comprises a mixture of polyvinylpyrrolidone and polyethylene glycol.

3. The method for preparing the filter membrane as described in claim 2, characterized in that, The polyvinylpyrrolidone is PVPK15.

4. The method for preparing the filter membrane as described in claim 2, characterized in that, The polyethylene glycol is PEG600.

5. The method for preparing the filter membrane as described in claim 1, characterized in that, In step (1), the amount of the membrane substrate material is 18-20%, where % refers to the mass percentage of the component relative to the mass of the casting solution; And / or, in step (1), the pore-forming agent includes 5-10% polyvinylpyrrolidone and 5-10% polyethylene glycol, wherein % refers to the mass percentage of the component relative to the mass of the casting solution; And / or, in step (1), the amount of silver acetylacetone used is 0.8%, 1% or 1.2%, where % refers to the mass percentage of the component relative to the mass of the casting solution; And / or, the amount of the organic solvent used is such that the mass of the casting solution is replenished to 100%.

6. The method for preparing the filter membrane as described in claim 5, characterized in that, In step (1), the amount of the membrane substrate material is 19%.

7. The method for preparing the filter membrane as described in claim 5, characterized in that, The amount of polyvinylpyrrolidone used is 6-8%.

8. The method for preparing the filter membrane as described in claim 5, characterized in that, The amount of polyethylene glycol used is 6-8%.

9. The method for preparing the filter membrane as described in claim 8, characterized in that, The amount of polyethylene glycol used is 7%.

10. The method for preparing the filter membrane according to claim 1, characterized in that, In step (2), the amine monomer is an amine monomer containing at least two amino groups; And / or, in step (2), the mass concentration of the amine monomer in the aqueous solution is 0.1-1.5 wt%, where wt% refers to the mass percentage of the amine monomer in the aqueous solution; And / or, the solvent of the aqueous phase solution is water; And / or, in step (2), the acyl chloride monomer is pyromellitic acid trimethylolpropionate (PMT); And / or, in step (2), the mass concentration of the acyl chloride monomer in the oil phase solution is 0.2-0.5 wt%, where wt% refers to the mass percentage of the oil phase monomer in the oil phase solution; And / or, in step (2), the solvent of the oil phase solution is one or more of n-hexane, isoalkanes L, G, and M.

11. The method for preparing the filter membrane according to claim 10, characterized in that, In step (2), the amine monomer is piperazine and / or m-diphenylamine.

12. The method for preparing the filter membrane as described in claim 10, characterized in that, In step (2), the mass concentration of the amine monomer in the aqueous solution is 0.2wt%, 0.4wt%, 0.5wt%, or 1.2wt%.

13. The method for preparing the filter membrane as described in claim 10, characterized in that, In step (2), the mass concentration of the acyl chloride monomer in the oil phase solution is 0.3 wt% or 0.4 wt%.

14. The method for preparing the filter membrane as described in claim 1, characterized in that, In step (2), the contact is performed by immersion; And / or, in step (2), the initial filter membrane is in contact with the aqueous solution for 4-6 minutes; And / or, in step (2), the solvent in the aqueous solution in the obtained initial filter membrane is completely evaporated after contact with the aqueous solution and before contact with the oil solution; And / or, in step (2), the initial filter membrane is in contact with the oil phase solution for more than 30 seconds; And / or, in step (2), after the initial filter membrane comes into contact with the oil phase solution, the solvent in the oil phase solution in the initial filter membrane is completely evaporated; and / or, after step (2), a post-processing step is also included.

15. The method for preparing the filter membrane as described in claim 14, characterized in that, In step (2), the immersion is carried out at room temperature; And / or, the contact is made by immersing the initial filter membrane in an aqueous or oil solution.

16. The method for preparing the filter membrane as described in claim 14, characterized in that, The initial filter membrane was in contact with the aqueous solution for 5 minutes.

17. The method for preparing the filter membrane according to claim 14, characterized in that, In step (2), the initial filter membrane is in contact with the oil phase solution for 30 seconds.

18. The method for preparing the filter membrane as described in claim 14, characterized in that, After step (2), the post-processing method is drying.

19. The method for preparing the filter membrane as described in claim 14, characterized in that, The post-processing temperature is 60-100℃.

20. The method for preparing the filter membrane according to claim 19, characterized in that, The post-processing temperature is 70, 80, or 90°C.

21. The method for preparing the filter membrane as described in claim 14, characterized in that, The post-processing time is 1-30 minutes.

22. The method for preparing the filter membrane according to claim 21, characterized in that, The post-processing time is 2, 5, 10, or 20 minutes.

23. A filter membrane prepared by the method of any one of claims 1-22.

24. A filter element, characterized in that, It includes the filter membrane as described in claim 23.

25. The application of a filter membrane as described in claim 23 or a filter cartridge as described in claim 24 in a water purification device.

26. The application as described in claim 25, characterized in that, The water purification equipment is a water purifier.