A high-flux microfiltration membrane and preparation method thereof

Abstract

The invention provides a high-flux microfiltration membrane and a preparation method thereof. The high-flux microfiltration membrane is mainly made of the following raw materials, by weight: 15-30 parts of a film-forming polymer, 10-17 parts of a solvent, 5-12 parts of a porogen, and 3-7 parts of a viscosity modifier. The membrane is suitable for large-scale liquid separation and filtration, has good chemical stability and mechanical strength, and can maintain stable filtration performance in harsh working environments.

Description

Technical Field

[0001] The invention belongs to the technical field of membrane separation, and in particular to a large-flux microfiltration membrane and a preparation method thereof. Background Art

[0002] Membrane separation technology, as an efficient and environmentally friendly separation method, plays a vital role in modern industry. Among them, microfiltration membrane, as an important component of membrane separation technology, is widely used in water treatment, dairy processing, biopharmaceuticals, food and beverages and other fields because it can effectively remove impurities such as microorganisms, bacteria, proteins, cells and suspended solids in liquids. The pore size of microfiltration membrane is usually larger than 0.1μm. This feature enables it to intercept larger particulate matter without causing significant obstruction to small molecules in the liquid, thereby ensuring filtration efficiency while also ensuring a higher liquid flux.

[0003] However, traditional microfiltration membrane preparation methods, such as phase inversion method, melt stretching method and nuclear track-etching method, face many challenges in the preparation of high-flux microfiltration membranes. Although the phase inversion method is relatively mature, the uniformity of the membrane structure is difficult to control during the preparation process, and the production efficiency is relatively low, which is difficult to meet the needs of large-scale production. The melt stretching method requires a high temperature and high pressure environment, which not only has high energy consumption, but also has limitations in physical properties and chemical stability of the prepared membrane materials. As for the nuclear track-etching method, although it can prepare a microfiltration membrane with uniform pore size distribution, its process is complicated, the cost is high, and it is difficult to achieve industrial production.

[0004] In the face of the shortcomings of the current microfiltration membrane preparation methods, it is an important issue to develop a new preparation method to meet the growing demand for microfiltration membranes in different fields.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The first purpose of the present invention is to provide a high-flux microfiltration membrane, which has excellent filtration performance, large flux and good stability, and at the same time has a large capacity, is suitable for large-scale liquid separation and filtration, and has good chemical stability and mechanical strength, and can maintain stable filtration performance in harsh working environments.

[0007] The second object of the present invention is to provide a method for preparing the above-mentioned high-flux microfiltration membrane, which prepares a microfiltration membrane with excellent filtration performance, high flux and good stability by coupling steam-induced phase separation and non-solvent-induced phase separation, combined with the addition of specific film-forming polymers, pore-forming agents and viscosity regulators.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: The invention provides a large flux microfiltration membrane, which is mainly prepared from the following raw materials, calculated by weight: 15-30 parts of a film-forming polymer, 10-17 parts of a solvent, 5-12 parts of a porogen and 3-7 parts of a viscosity regulator.

[0009] Preferably, as a further feasible solution, the following components are used in parts by mass: 17-28 parts of film-forming polymer, 12-16 parts of solvent, 8-11 parts of porogen and 4-6 parts of viscosity modifier.

[0010] Preferably, as a further feasible solution, the following components are used in parts by mass: 25 parts of film-forming polymer, 15 parts of solvent, 10 parts of porogen and 5 parts of viscosity modifier.

[0011] Preferably, the film-forming polymer is one or more of polysulfone, polyethersulfone, polyvinylidene fluoride and polyvinyl chloride.

[0012] Preferably, the solvent is one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0013] Preferably, the porogen is one or more of polyethylene glycol and polyvinyl pyrrolidone.

[0014] Preferably, the viscosity modifier is one or more of methanol, acetic acid and water.

[0015] In the above-mentioned materials of the present invention, the film-forming polymer is the main structural component of the membrane. The film-forming polymer provides the necessary strength and chemical stability, ensuring that the microfiltration membrane is not easily damaged or degraded during use; the type of film-forming polymer is selected because it can directly affect the size of the pore size of the microfiltration membrane, further affecting the filtration efficiency and retention performance of the microfiltration membrane.

[0016] The reason for using solvents is that they can completely dissolve the membrane-forming polymers to form a uniform casting solution, and the interaction between the solvent's volatilization rate and the polymer can further affect the pore structure and pore size distribution of the microfiltration membrane, thereby affecting the permeability of the microfiltration membrane. The choice and proportion of solvents are crucial to the solubility of the membrane-forming polymer and the stability of the casting solution; the volatility of the solvent and the compatibility of the polymer jointly determine the pore structure and pore size distribution of the microfiltration membrane, thereby affecting the filtration efficiency and retention performance of the microfiltration membrane.

[0017] Porogens act as temporary spacers during the formation of microfiltration membranes. As the solvent evaporates, they can gradually precipitate, leaving pores and increasing the porosity and permeability of the microfiltration membrane. The choice of porogen type and concentration will directly affect the pore size and distribution of the microfiltration membrane, thereby adjusting the filtration performance of the microfiltration membrane.

[0018] Viscosity regulators not only affect the pore structure and pore size distribution of the membrane by adjusting the viscosity of the casting solution, but also ensure the uniformity and stability during the preparation of the microfiltration membrane. Appropriate viscosity regulators help to form a more uniform and finer pore structure, improve the filtration efficiency and retention performance of the membrane. At the same time, viscosity regulators can also help control the gelation rate during the preparation of the microfiltration membrane, ensuring that the structure and performance of the microfiltration membrane meet expectations.

[0019] In addition to providing a high-flux microfiltration membrane, the present invention also provides a method for preparing the high-flux microfiltration membrane, comprising the following steps: adding a film-forming polymer into a solvent to prepare a film-forming solution; Add the porogen into the film-forming solution and stir to fully dissolve it; Then add the viscosity regulator and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after static degassing onto the surface of the carrier to form a liquid film; exposing the obtained liquid film to a certain steam atmosphere for steam treatment; The liquid film is then transferred to a coagulation bath for non-solvent-induced phase separation to form a membrane; The membrane is then kept in the coagulation bath to allow the phase inversion process to proceed completely; The membrane with complete phase inversion was immersed in a glycerol aqueous solution, taken out and dried naturally.

[0020] Preferably, the liquid film is exposed to a certain steam atmosphere for 12-17 minutes.

[0021] Preferably, the film is kept in the coagulation bath for 27-33 minutes.

[0022] In the preparation method of the present invention, the film-forming polymer is dissolved in a solvent to form a uniform film-forming solution, which is the basis for preparing the microfiltration membrane. A suitable solvent can ensure that the film-forming polymer is fully dissolved to ensure the uniformity and stability of the microfiltration membrane.

[0023] The addition of porogens is intended to form the pore structure of the microfiltration membrane. The porogens play a placeholder role in the process of microfiltration membrane formation and are removed in the subsequent phase separation step, leaving pores. The addition of viscosity modifiers is used to adjust the viscosity of the membrane-forming solution to control the thickness and pore structure of the microfiltration membrane. Appropriate viscosity helps to form a stable liquid film to prevent rupture or deformation during the subsequent preparation process. Static degassing treatment can remove bubbles in the membrane-forming solution to prevent bubbles from forming defects during the formation of the microfiltration membrane and affecting the filtration performance of the microfiltration membrane.

[0024] Steam treatment is to partially solidify the surface of the microfiltration membrane through steam-induced phase separation to form a preliminary pore structure. This step is beneficial to optimize the internal structure of the microfiltration membrane and improve the permeability of the microfiltration membrane.

[0025] Transferring the liquid film treated with steam to the coagulation bath allows the solvent in the liquid film to interact with the non-solvent in the coagulation bath, resulting in the aggregation and precipitation of polymer chains, thereby forming the structure of the microfiltration membrane. Phase separation and the formation of the microfiltration membrane require time to be fully carried out, so the microfiltration membrane after the initial phase separation still needs to continue to be in the coagulation bath for a period of time. A new, unused coagulation bath is used here to avoid interference with the microfiltration membrane formation process due to polymers and other impurities that already exist in the previous coagulation bath. Prolonging the time the microfiltration membrane stays in the coagulation bath is to allow for more sufficient exchange and interaction, forming a more stable and uniform microfiltration membrane structure, and helping the final microfiltration membrane to have a large flux and good filtration performance.

[0026] Immersing the microfiltration membrane in a glycerol aqueous solution will improve the smoothness and glossiness of its surface. As a plasticizer, glycerol can penetrate into the molecular structure of the microfiltration membrane, increase the sliding properties between molecular chains, and thus improve the toughness of the microfiltration membrane. At the same time, glycerol can also enhance the strength of the microfiltration membrane to a certain extent, making it more durable during use; the membrane treated with glycerol can maintain good elastic recovery after drying. This means that after being subjected to external forces, the membrane can quickly return to its original shape and size and maintain the stability of its structure.

[0027] Compared with the prior art, the present invention has the following beneficial effects: By adopting the preferred ratio of specific film-forming polymers, solvents, porogens and viscosity modifiers, and combining the coupling technology of steam-induced phase separation and non-solvent-induced phase separation, the present invention successfully prepared a high-flux microfiltration membrane. The microfiltration membrane has a uniform pore size distribution and an optimized internal structure, which significantly improves the filtration efficiency and capacity, making it suitable for large-scale liquid separation and filtration.

[0028] In addition, the preparation method of the present invention further optimizes the performance of the microfiltration membrane by finely controlling the process steps, such as the time the liquid film is exposed to the steam atmosphere and the time the microfiltration membrane continues to be stored in the coagulation bath. The prepared microfiltration membrane not only has a large capacity and excellent filtration performance, but also exhibits good chemical stability and mechanical strength. These characteristics enable the microfiltration membrane to maintain stable filtration performance in harsh working environments, thereby greatly extending its service life and scope of application.

[0029] The high-flux microfiltration membrane and preparation method of the present invention have made significant progress in solving the problems of low production efficiency and uneven microfiltration membrane structure in the prior art, and provide a new, efficient and stable solution for large-scale liquid separation and filtration. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0031] Example 1 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 15 g of polysulfone and add it to 10 g of N-methylpyrrolidone to prepare a membrane-forming solution; Then, 5 g of polyethylene glycol was added to the film-forming solution and mixed and stirred to fully dissolve; Add 3g of methanol and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the glass substrate; Use a 0.2 mm scraper to slowly and evenly cast the solution on the surface of the glass substrate to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 17 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 33 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0032] Example 2 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 20g of polyethersulfone and add it to 12g of N,N-dimethylformamide to prepare a membrane-forming solution; Then, 8 g of polyethylene glycol was added to the film-forming solution and mixed and stirred to fully dissolve; Add 4g of acetic acid and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the steel belt; Use a 0.2mm scraper to slowly and evenly cast the solution on the surface of the steel belt to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 14 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 27 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0033] Example 3 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 25g of polyvinylidene fluoride and add it to 15g of N,N-dimethylformamide to prepare a film-forming solution; Then, 10 g of polyethylene glycol was added to the film-forming solution and mixed and stirred to fully dissolve; Add 5g of water and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the release paper coated with silicone rubber; Use a 0.2mm scraper to slowly and evenly cast the solution on the surface of the release paper coated with silicone rubber to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 15 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then, the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 30 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0034] Example 4 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 30g of polyvinyl fluoride and add it to 10g of dimethyl sulfoxide to prepare a membrane-forming solution; Then, 5 g of polyvinyl pyrrolidone was added to the film-forming solution and mixed and stirred to fully dissolve; Add 5g of methanol and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the roller; Use a 0.2mm scraper to slowly and evenly cast the solution on the roller surface to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 14 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then, the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 30 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0035] Example 5 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: 10 g of polysulfone and 5 g of polyethersulfone were added to 12 g of N-methylpyrrolidone to prepare a membrane-forming solution; Then, 8 g of polyvinyl pyrrolidone was added to the film-forming solution and mixed and stirred to fully dissolve; Add 5g of acetic acid and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the glass substrate; Use a 0.2 mm scraper to slowly and evenly cast the solution on the surface of the glass substrate to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 15 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 31 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0036] Example 6 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: 10 g of polyethersulfone and 10 g of polyvinylidene fluoride were added to 15 g of N,N-dimethylformamide to prepare a membrane-forming solution; Then, 10 g of polyvinyl pyrrolidone was added to the film-forming solution and mixed and stirred to fully dissolve; Add 4g of water and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the steel belt; Use a 0.2mm scraper to slowly and evenly cast the solution on the surface of the steel belt to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 13 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 31 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0037] Example 7 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: 15 g of polyethersulfone and 15 g of polyvinylidene fluoride were added to 12 g of N,N-dimethylformamide to prepare a membrane-forming solution; Then, 5 g of polyethylene glycol was added to the film-forming solution and mixed and stirred to fully dissolve; Add 4g of methanol and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the release paper coated with silicone rubber; Use a 0.2mm scraper to slowly and evenly cast the solution on the surface of the release paper coated with silicone rubber to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 15 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 29 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0038] Example 8 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: 12 g of polyvinylidene fluoride and 13 g of polyvinyl chloride were added to 12 g of dimethyl sulfoxide to prepare a membrane-forming solution; Then, 8 g of polyethylene glycol was added to the film-forming solution and mixed and stirred to fully dissolve; Add 4g of acetic acid and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the roller; Use a 0.2mm scraper to slowly and evenly cast the solution on the roller surface to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 16 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then, the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 30 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0039] Example 9 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 20 g of polyethersulfone and add it to 12 g of N-methylpyrrolidone to prepare a film-forming solution; Then, 11 g of polyethylene glycol was added to the film-forming solution and mixed and stirred to fully dissolve; Add 6g of water and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the glass substrate; Use a 0.2 mm scraper to slowly and evenly cast the solution on the surface of the glass substrate to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 12 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then, the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 30 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0040] Example 10 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 28 g of polyethersulfone and add it to 17 g of N,N-dimethylformamide to prepare a membrane-forming solution; Then, 5 g of polyvinyl pyrrolidone was added to the film-forming solution and mixed and stirred to fully dissolve; Add 5g of methanol and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the steel belt; Use a 0.2mm scraper to slowly and evenly cast the solution on the surface of the steel belt to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 15 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then, the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 30 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0041] Embodiment 11 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 15g of polyvinyl chloride and add it to 10g of N,N-dimethylformamide to prepare a film-forming solution; Then, 8 g of polyvinyl pyrrolidone was added to the film-forming solution and mixed and stirred to fully dissolve; Add 5g of acetic acid and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the release paper coated with silicone rubber; Use a 0.2mm scraper to slowly and evenly cast the solution on the surface of the release paper coated with silicone rubber to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 15 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then, the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 30 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0042] Example 12 The specific preparation process of the high flux microfiltration membrane of this embodiment is carried out according to the following steps: Take 15g of polyvinyl chloride and add it to 16g of dimethyl sulfoxide to prepare a membrane-forming solution; Then, 12 g of polyvinyl pyrrolidone was added to the film-forming solution and mixed and stirred to fully dissolve; Add 7g of water and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after standing and degassing onto one end of the steel belt; Use a 0.2mm scraper to slowly and evenly cast the solution on the surface of the steel belt to form a film with uniform thickness; The obtained membrane liquid was exposed to a steam atmosphere with a relative humidity of 90% for 14 minutes; The membrane solution was then transferred to a dimethyl sulfoxide aqueous solution coagulation bath for non-solvent-induced phase separation to form a membrane; Then the membrane was kept in a fresh dimethyl sulfoxide aqueous solution coagulation bath for 31 min to complete the phase conversion. Finally, the membrane with complete phase conversion was immersed in a glycerol aqueous solution for 24 hours, taken out and dried naturally to obtain a high-flux microfiltration membrane.

[0043] Comparative Example 1 The specific implementation method is consistent with Example 3, and the dosage of each substance is changed. The specific changes are shown in Table 1.

[0044] Table 1. Changes in dosage of each substance

[0045] Experimental Example 1 The microfiltration membranes prepared in the above Examples 1-12 and the microfiltration membranes prepared in Scheme 1-8 in Comparative Example 1 were subjected to the following tests: the prepared microfiltration membranes were immersed in a NaOH solution at 35°C and 0.5 mol / L for 0 days, 7 days, and 30 days. At 1.0 MPa, the flux of the microfiltration membranes was tested before and after static soaking, the retention rate of inorganic salts was measured, and the changes on the membrane surface were observed. The experimental results are shown in Tables 2 and 3.

[0046] Table 2. Experimental results of the examples

[0047] Table 3. Experimental results of comparative examples

[0048] Based on the above data, we can draw the following conclusions: According to the above data, from the experimental results of Example 1 to Example 12, after the prepared microfiltration membrane was immersed in the NaOH solution for 0 days, 7 days, and 30 days, the flux decreased but not significantly, and the retention rate remained in a relatively stable range, and there was no obvious change on the membrane surface before and after immersion. The flux did not decrease significantly in a harsh environment for a long time, and the retention rate was still maintained at more than 85%, indicating that the prepared microfiltration membrane has good chemical stability and excellent performance.

[0049] However, the flux and rejection rate of the microfiltration membranes prepared by Schemes 1 to 8 in Comparative Example 1 were lower than those in the embodiment under the same test conditions. More importantly, the microfiltration membranes in Comparative Example 1 were damaged on the membrane surface after being immersed in the NaOH solution for 7 days and 30 days, indicating that the microfiltration membranes prepared by the scheme in Comparative Example 1 had poor chemical stability.

[0050] The microfiltration membrane composition ratio is carefully designed and the preparation process is optimized to obtain a microfiltration membrane with excellent filtration performance, large flux and good stability. However, Schemes 1 to 8 in Comparative Example 1 change the composition ratio of the microfiltration membrane, such as excessive use of certain ingredients, resulting in reduced performance of the prepared microfiltration membrane.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high flux microfiltration membrane, characterized in that: The invention is mainly prepared from the following raw materials in parts by mass: 15-30 parts of film-forming polymer, 10-17 parts of solvent, 5-12 parts of pore-forming agent and 3-7 parts of viscosity regulator.

2. The high flux microfiltration membrane according to claim 1, characterized in that: In parts by mass: 17-28 parts of film-forming polymer, 12-16 parts of solvent, 8-11 parts of porogen and 4-6 parts of viscosity regulator.

3. The high flux microfiltration membrane according to claim 1, characterized in that: In parts by mass: 25 parts of film-forming polymer, 15 parts of solvent, 10 parts of porogen and 5 parts of viscosity modifier.

4. The high flux microfiltration membrane according to any one of claims 1 to 3, characterized in that: The film-forming polymer is one or more of polysulfone, polyethersulfone, polyvinylidene fluoride and polyvinyl chloride.

5. The high flux microfiltration membrane according to any one of claims 1 to 3, characterized in that: The solvent is one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

6. The high flux microfiltration membrane according to any one of claims 1 to 3, characterized in that: The porogen is one or more of polyethylene glycol and polyvinyl pyrrolidone.

7. The high flux microfiltration membrane according to any one of claims 1 to 3, characterized in that: The viscosity modifier is one or more of methanol, acetic acid and water.

8. A method for preparing a high-flux microfiltration membrane according to any one of claims 1 to 7, characterized in that: The steps include: adding a film-forming polymer into a solvent to prepare a film-forming solution; Add the porogen into the film-forming solution and stir to fully dissolve it; Then add the viscosity regulator and mix thoroughly to adjust the viscosity, then let it stand to degas; Pour the solution obtained after static degassing onto the surface of the carrier to form a liquid film; exposing the obtained liquid film to a certain steam atmosphere for steam treatment; The liquid film is then transferred to a coagulation bath for non-solvent-induced phase separation to form a membrane; The membrane is then kept in the coagulation bath to allow the phase inversion process to proceed completely; The membrane with complete phase inversion was immersed in a glycerol aqueous solution, taken out and dried naturally.

9. The method for preparing a high-flux microfiltration membrane according to claim 8, characterized in that: The liquid film is exposed to a certain steam atmosphere for 12-17 minutes.

10. The method for preparing a high-flux microfiltration membrane according to claim 8, characterized in that: The membrane was kept in the coagulation bath for 27-33 minutes.

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