Ceramic reinforced hollow fiber membrane and preparation method thereof

Abstract

The invention relates to the technical field of hollow fiber ceramic membranes, and discloses a ceramic reinforced hollow fiber membrane and a preparation method thereof.The ceramic reinforced hollow fiber membrane comprises a membrane body, the membrane body is composed of composite fibers and homogeneous polymer membrane casting liquid coating the outer surfaces of the composite fibers, and the composite fibers are prepared by evenly mixing inorganic ceramic powder and membrane polymer powder; the inorganic ceramic powder is prepared by mixing one or more of silicon carbide, aluminum oxide or zirconium oxide. According to the ceramic reinforced hollow fiber membrane and the preparation method thereof, the inorganic ceramic powder is fixed in the homogeneous polymer by adopting a high-temperature melt spinning technology in a production process of the ceramic reinforced hollow fiber membrane, so that the inorganic ceramic powder is immobilized and cannot fall off in a subsequent continuous use process, and therefore, the ceramic reinforced hollow fiber membrane has a good application prospect. The problem that inorganic ceramic particles of the inorganic ceramic / polymer composite hollow fiber obtained by directly mixing in a membrane casting solution for spinning are easy to peel and fall off is effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field of hollow fiber ceramic membranes, in particular to a ceramic reinforced hollow fiber membrane and a preparation method thereof. Background Art

[0002] Hollow fiber ceramic membranes combine the advantages of organic membrane and inorganic membrane preparation methods. Hollow fiber ceramic membranes have unique advantages over traditional ceramic membranes, such as larger specific surface area, self-supporting membrane formation, simple process and low cost. Therefore, they have broad application potential and competitiveness in many fields.

[0003] The existing ceramic reinforced hollow fiber membrane needs to work in a water flow environment when in use, so as to filter water. However, the existing fiber membranes are often made of PET polyester fibers, which makes the strength of the fiber membrane itself limited, and the adhesion between these polyester fibers and the equipment is poor, making the limiting membrane easily affected by external forces during use and peeling off from the equipment, thereby affecting the use effect and service life of the hollow fiber membrane; in view of this, we proposed a ceramic reinforced hollow fiber membrane and a preparation method thereof. Summary of the invention

[0004] The object of the present invention is to provide a ceramic reinforced hollow fiber membrane and a preparation method thereof to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a ceramic reinforced hollow fiber membrane, comprising a membrane body, wherein the membrane body is composed of a composite fiber and a homogeneous polymer casting liquid coated on the outer surface of the composite fiber, the composite fiber is made by mixing inorganic ceramic powder and membrane polymer powder, the inorganic ceramic powder is made by mixing one or a mixture of silicon carbide, aluminum oxide or zirconium oxide, the membrane polymer is made by mixing one or a mixture of polysulfone or polyethersulfone, polyvinylidene fluoride, and the homogeneous polymer casting liquid is made by mixing silicon carbide polymer, porogen, inorganic filler and solvent.

[0006] Preferably, the porogen is polyvinyl pyrrolidone, and the amount of the porogen added is 10% to 15%. By using polyvinyl pyrrolidone as an additive to improve the hydrophilicity and pore structure of the membrane, the membrane formation process can be synchronously regulated by controlling the amount and conditions of polyvinyl pyrrolidone added, thereby preparing a membrane material with specific properties and structure. The inorganic filler is one or a mixture of alumina, zirconium oxide, silicon dioxide, and talc, and the component content of the inorganic filler is 3% to 5%, which can effectively improve the mechanical strength, wear resistance, corrosion resistance and thermal stability of the hollow fiber membrane. By selecting suitable inorganic fillers and appropriate filling amounts, the comprehensive performance of ceramic reinforced hollow fiber membranes can be optimized to meet different product requirements.

[0007] A method for preparing a ceramic reinforced hollow fiber membrane comprises the following steps:

[0008] S1. Prepare powder raw materials: grind one or more powder materials of silicon carbide, aluminum oxide or zirconium oxide to 600-800 mesh and set aside to obtain inorganic ceramic powder, then grind one or more mixture powder materials of polysulfone or polyethersulfone, polyvinylidene fluoride to 600-800 mesh and set aside to obtain polymer powder for membrane;

[0009] S2, high temperature melting: adding the inorganic ceramic powder obtained in S1 to the membrane polymer powder and mixing them first, and then melting the mixture at a high temperature to obtain a molten mixture;

[0010] S3, preparing inorganic ceramic powder / polymer composite fibers: inputting the molten mixture obtained in S2 into a melt spinning machine, and spinning the inorganic ceramic powder / polymer composite fibers through the nozzle and stretching device of the melt spinning machine;

[0011] S4, preparing a homogeneous polymer casting solution: adding a certain mass of silicon carbide polymer, porogen, and inorganic filler into a solvent in sequence, and mixing and stirring until the solution is in a uniform state without precipitation, so as to obtain a homogeneous polymer casting solution;

[0012] S5, coating with homogeneous polymer casting liquid: the inorganic ceramic powder / polymer composite fiber obtained in S3 is woven into a fiber tube online, and then the homogeneous polymer casting liquid obtained in S4 is uniformly coated on the outer surface of the fiber tube;

[0013] S6. Preparation by phase inversion synchronous technology: The fiber tube coated with the homogeneous polymer casting liquid in S5 is prepared by phase inversion synchronous technology to obtain a ceramic reinforced hollow fiber membrane.

[0014] Preferably, a ball mill is used for processing when preparing the powder raw material in S1, and the discharge end of the ball mill is provided with a return assembly and a screening assembly, the return assembly is arranged on the side of the screening assembly, and the return assembly is connected to the feed port of the ball mill through a conveyor belt to ensure that the mesh size of the powder raw material reaches a qualified state, thereby facilitating the mixing of the powder and the subsequent preparation of the molten mixture.

[0015] Preferably, the high-temperature melting temperature in S2 is set at 150-180°C, and the inorganic ceramic powder after mixing is added to the membrane polymer powder and fed into the high-temperature melting equipment in a quantitative and sequential manner to avoid the situation where too much material is added at one time, resulting in different melting states of the materials in the high-temperature melting equipment. Before feeding, the mixture is preheated by a waste heat recovery system arranged outside the high-temperature melting equipment to improve the melting processing efficiency of the equipment.

[0016] Preferably, the diameter of the inorganic ceramic powder / polymer composite fibers prepared by the melt spinning machine in S3 is set at 50μm-200μm, and the inorganic ceramic powder / polymer composite fibers prepared by melt spinning are collected after being cooled to room temperature by air using side blowing, ring blowing and center blowing, so that the inorganic ceramic powder / polymer composite fibers are in a relatively stable state and facilitate subsequent spinning operations.

[0017] Preferably, the silicon carbide polymer used in S4 is directly mixed with silicon carbide powder and polymer resin, and the two are evenly dispersed by stirring and kneading, and then formed and cured to obtain a silicon carbide polymer composite material, thereby ensuring the high hardness, wear resistance, corrosion resistance and good thermal stability of silicon carbide itself while maintaining the advantages of easy processing and toughness of the composite polymer, thereby improving the overall quality of ceramic reinforced hollow fiber membrane products.

[0018] Preferably, before coating the homogeneous polymer casting liquid in S5, the outer surface of the fiber tube is first ground to ensure the flatness of the outer surface of the fiber tube. Then, a scraper or coater is used to perform coating during the coating process to ensure the uniformity of the coating effect on the outer surface of the fiber tube. After the coating operation is completed, a drying device is used for drying and curing. The temperature of the drying device is controlled at 60-80°C to avoid deformation or cracking of the membrane material.

[0019] Preferably, the phase inversion synchronization technique used in S6 comprises the following steps:

[0020] S61, immersing the fiber tube coated with the homogeneous polymer casting solution in pure water for a certain period of time, so that the solvent and the non-solvent diffuse with each other. When the diffusion reaches a certain level, the homogeneous polymer casting solution becomes a thermodynamically unstable system, resulting in phase separation of the homogeneous polymer casting solution;

[0021] S62. After the homogeneous polymer casting liquid system is separated into phases, the solvent and non-solvent are further exchanged, and the membrane pores are condensed, the phases flow, and the polymer-rich phase solidifies into a membrane, and finally a stable membrane is formed on the outside of the fiber tube.

[0022] Preferably, the membrane wall thickness of the membrane body is set at 0.1-0.7 mm, and the inner diameter thereof is set at 0.4-2.2 mm, so as to ensure the strength of the ceramic reinforced hollow fiber membrane itself and the filtering effect on the water flow, and facilitate people's use.

[0023] Compared with the prior art, the present invention provides a ceramic reinforced hollow fiber membrane and a preparation method thereof, which has the following beneficial effects:

[0024] 1. The ceramic reinforced hollow fiber membrane and its preparation method use high-temperature melt spinning technology in the production process of the ceramic reinforced hollow fiber membrane to fix the inorganic ceramic powder in a homogeneous polymer, so that the inorganic ceramic powder is fixed and will not fall off during subsequent continuous use. Therefore, the problem of easy peeling and falling off of the inorganic ceramic particles of the inorganic ceramic / polymer composite hollow fiber obtained by spinning directly mixed in the casting liquid is effectively avoided.

[0025] 2. The ceramic reinforced hollow fiber membrane and its preparation method use inorganic ceramic powder to replace the existing polyester fiber in the preparation of the ceramic reinforced hollow fiber membrane to improve the overall strength of the hollow fiber membrane, thereby ensuring its use effect and service life. The tensile strength of the traditional polymer membrane is only 2-4N, while the strength of the inorganic ceramic polymer hybrid fiber reinforced hollow fiber membrane is 10-100N.

[0026] 3. The ceramic reinforced hollow fiber membrane and its preparation method, since the strength and toughness of the inorganic ceramic powder polymer hybrid fiber are better than those of the pure polymer fiber, and the fiber is used to reinforce the homogeneous polymer membrane, since the polymer in the inorganic ceramic powder polymer hybrid fiber is consistent with the material of the membrane itself, the hybrid fiber and the separation membrane are easier to bond together, that is, semi-homogeneous reinforcement, thereby solving the problem of poor adhesion and easy falling off of the reinforced fiber and the hollow fiber membrane polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the ceramic reinforced hollow fiber membrane of the present invention;

[0028] Figure 2 It is a schematic diagram of the process flow of preparing the ceramic reinforced hollow fiber membrane of the present invention.

[0029] In the figure: 1. Membrane. DETAILED DESCRIPTION

[0030] like Figure 1-Figure 2As shown, the present invention provides a technical solution: a ceramic reinforced hollow fiber membrane includes a membrane body 1, the membrane body 1 is composed of a composite fiber and a homogeneous polymer casting liquid coated on the outer surface of the composite fiber, the composite fiber is made by mixing inorganic ceramic powder and membrane polymer powder, the inorganic ceramic powder is made by mixing one or a mixture of silicon carbide, aluminum oxide or zirconium oxide, the membrane polymer is made by mixing one or a mixture of polysulfone or polyethersulfone, polyvinylidene fluoride, the homogeneous polymer casting liquid is made by mixing silicon carbide polymer, porogen, inorganic filler and solvent, and the porogen is polyvinyl pyrrolidone, and the addition amount of the porogen is 10%. ~15%, polyvinyl pyrrolidone is used as an additive to improve the hydrophilicity and pore structure of the membrane, and by controlling the amount and conditions of polyvinyl pyrrolidone added, the membrane formation process can be synchronously adjusted to prepare a membrane material with specific properties and structure. The inorganic filler adopts one or a mixture of alumina, zirconia, silica, and talcum powder, and the component content of the inorganic filler is 3% to 5%, which can effectively improve the mechanical strength, wear resistance, corrosion resistance and thermal stability of the hollow fiber membrane. By selecting suitable inorganic fillers and appropriate filling amounts, the comprehensive performance of the ceramic reinforced hollow fiber membrane can be optimized to meet different product requirements.

[0031] In the technical solution of the present invention, the method for preparing a ceramic reinforced hollow fiber membrane comprises the following steps:

[0032] S1. Prepare powder raw materials: grind one or more powder materials of silicon carbide, aluminum oxide or zirconium oxide to 600-800 mesh and set aside to obtain inorganic ceramic powder, then grind one or more mixture powder materials of polysulfone or polyethersulfone, polyvinylidene fluoride to 600-800 mesh and set aside to obtain polymer powder for membrane;

[0033] S2, high temperature melting: adding the inorganic ceramic powder obtained in S1 to the membrane polymer powder and mixing them first, and then melting the mixture at a high temperature to obtain a molten mixture;

[0034] S3, preparing inorganic ceramic powder / polymer composite fibers: inputting the molten mixture obtained in S2 into a melt spinning machine, and spinning the inorganic ceramic powder / polymer composite fibers through the nozzle and stretching device of the melt spinning machine;

[0035] S4, preparing a homogeneous polymer casting solution: adding a certain mass of silicon carbide polymer, porogen, and inorganic filler into a solvent in sequence, and mixing and stirring until the solution is in a uniform state without precipitation, so as to obtain a homogeneous polymer casting solution;

[0036] S5, coating with homogeneous polymer casting liquid: the inorganic ceramic powder / polymer composite fiber obtained in S3 is woven into a fiber tube online, and then the homogeneous polymer casting liquid obtained in S4 is uniformly coated on the outer surface of the fiber tube;

[0037] S6. Preparation by phase inversion synchronous technology: The fiber tube coated with the homogeneous polymer casting liquid in S5 is prepared by phase inversion synchronous technology to obtain a ceramic reinforced hollow fiber membrane.

[0038] The phase inversion synchronization technique used in S6 includes the following steps:

[0039] S61, immersing the fiber tube coated with the homogeneous polymer casting solution in pure water for a certain period of time, so that the solvent and the non-solvent diffuse with each other. When the diffusion reaches a certain level, the homogeneous polymer casting solution becomes a thermodynamically unstable system, resulting in phase separation of the homogeneous polymer casting solution;

[0040] S62. After the homogeneous polymer casting liquid system is separated into phases, the solvent and non-solvent are further exchanged, and the membrane pores are condensed, the phases flow, and the polymer-rich phase solidifies into a membrane, and finally a stable membrane is formed on the outside of the fiber tube.

[0041] Specifically, a ball mill is used for processing when preparing the powder raw material in S1, and the discharge end of the ball mill is provided with a return component and a screening component. The screening component can be replaced and controlled according to the processing accuracy to ensure that the powder material is within the corresponding mesh number range to facilitate subsequent further processing. The return component is arranged on the side of the screening component, and the return component is connected to the feed port of the ball mill through a conveyor belt to ensure that the mesh number of the powder raw material reaches a qualified state, thereby facilitating the mixing of the powder and the preparation of the subsequent molten mixture. By providing the return component, a batch of materials can be ground multiple times to finally reach the required mesh number range, thereby reducing material waste and appropriately reducing the screening pressure of the screening component. At the same time, S The high-temperature melting temperature in 2 is set at 150-180°C, which can make the production materials quickly enter the melting state without decomposition, ensuring the melting quality of the product. The inorganic ceramic powder after mixing is added to the membrane polymer powder. When feeding into the high-temperature melting equipment, quantitative feeding is adopted to avoid adding too much material at one time, resulting in different melting states of the materials in the high-temperature melting equipment. The feeding amount can be accurately controlled to avoid feeding errors, affect the material ratio accuracy of the product, and thus reduce the overall quality of the product. Before feeding, the mixture is preheated by the waste heat recovery system set outside the high-temperature melting equipment to improve the melting processing efficiency of the equipment.

[0042] In addition, the diameter of the inorganic ceramic powder / polymer composite fiber prepared by the melt spinning machine in S3 is set at 50μm-200μm, and the inorganic ceramic powder / polymer composite fiber prepared by melt spinning is collected after being cooled to room temperature by air in the form of side blowing, ring blowing and center blowing, so that the inorganic ceramic powder / polymer composite fiber is in a relatively stable state and convenient for subsequent spinning operations. Furthermore, the silicon carbide polymer used in S4 is directly mixed with silicon carbide powder and polymer resin, and the two are evenly dispersed by stirring and kneading, and then formed and cured to obtain a silicon carbide polymer composite material, ensuring the high hardness, wear resistance, corrosion resistance and good thermal stability of silicon carbide itself while the advantages of easy processing and toughness of the composite polymer, thereby improving the overall quality of ceramic reinforced hollow fiber membrane products.

[0043] In an embodiment of the present invention, before coating the homogeneous polymer casting liquid in S5, the outer surface of the fiber tube is first ground to ensure the flatness of the outer surface of the fiber tube. Then, a scraper or a coater is used to perform the coating operation during the coating operation, and the uniformity of the coating effect on the outer surface of the fiber tube is ensured. After the coating operation is completed, the fiber tube is dried and cured using a drying device. The temperature of the drying device is controlled at 60-80°C to avoid deformation or cracking of the membrane material. After production is completed, the cured membrane can be further processed according to actual usage requirements, such as cutting, cleaning, etc., to improve product quality. Since the material of the homogeneous polymer casting liquid contains the same components as those in the inorganic ceramic powder / polymer composite fiber, the intermolecular affinity of the same components between the two is stronger after the fiber tube made of the composite fiber is coated and cured, and it is also easier to ensure the fixing effect of the membrane on the fiber tube, thereby avoiding the problem of falling off during use.

[0044] In the present invention, the membrane wall thickness of the membrane body 1 is set at 0.1-0.7 mm, and the inner diameter thereof is set at 0.4-2.2 mm, so as to ensure the strength of the ceramic reinforced hollow fiber membrane itself and the filtering effect on the water flow, and facilitate people's use.

[0045] The above generally describes the present invention in detail, but it is obvious to a person skilled in the art that some modifications or improvements can be made to the present invention. Therefore, modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A ceramic reinforced hollow fiber membrane, characterized in that: The invention comprises a membrane body (1), wherein the membrane body (1) is composed of a composite fiber and a homogeneous polymer casting liquid coated on the outer surface of the composite fiber, wherein the composite fiber is made by mixing an inorganic ceramic powder with a membrane polymer powder, wherein the inorganic ceramic powder is made by mixing one or a mixture of silicon carbide, aluminum oxide or zirconium oxide, wherein the membrane polymer is made by mixing one or a mixture of polysulfone or polyethersulfone, polyvinylidene fluoride, and wherein the homogeneous polymer casting liquid is made by mixing a silicon carbide polymer, a porogen, an inorganic filler and a solvent.

2. The ceramic reinforced hollow fiber membrane according to claim 1, characterized in that: The porogen is polyvinyl pyrrolidone, and the addition amount of the porogen is 10% to 15%. Polyvinyl pyrrolidone is used as an additive, the addition amount and conditions of polyvinyl pyrrolidone are controlled, and the film formation process is synchronously adjusted. The inorganic filler is one or a mixture of alumina, zirconium oxide, silicon dioxide, and talcum powder, and the component content of the inorganic filler is 3% to 5%.

3. A method for preparing a ceramic reinforced hollow fiber membrane as claimed in claim 1-2, characterized in that: The following steps are involved: S1. Prepare powder raw materials: grind one or more powder materials of silicon carbide, aluminum oxide or zirconium oxide to 600-800 mesh and set aside to obtain inorganic ceramic powder, then grind one or more mixture powder materials of polysulfone or polyethersulfone, polyvinylidene fluoride to 600-800 mesh and set aside to obtain polymer powder for membrane; S2, high temperature melting: adding the inorganic ceramic powder obtained in S1 to the membrane polymer powder and mixing them first, and then melting the mixture at a high temperature to obtain a molten mixture; S3, preparing inorganic ceramic powder / polymer composite fibers: inputting the molten mixture obtained in S2 into a melt spinning machine, and spinning the inorganic ceramic powder / polymer composite fibers through the nozzle and stretching device of the melt spinning machine; S4, preparing a homogeneous polymer casting solution: adding a certain mass of silicon carbide polymer, porogen, and inorganic filler into a solvent in sequence, and mixing and stirring until the solution is in a uniform state without precipitation, so as to obtain a homogeneous polymer casting solution; S5, coating with homogeneous polymer casting liquid: the inorganic ceramic powder / polymer composite fiber obtained in S3 is woven into a fiber tube online, and then the homogeneous polymer casting liquid obtained in S4 is uniformly coated on the outer surface of the fiber tube; S6. Preparation by phase inversion synchronous technology: The fiber tube coated with the homogeneous polymer casting liquid in S5 is prepared by phase inversion synchronous technology to obtain a ceramic reinforced hollow fiber membrane.

4. The method for preparing a ceramic reinforced hollow fiber membrane according to claim 3, characterized in that: When preparing the powder raw material in S1, a ball mill is used for processing, and the discharge end of the ball mill is provided with a return component and a screening component, the return component is arranged on the side of the screening component, and the return component is connected to the feed port of the ball mill through a conveyor belt.

5. The method for preparing a ceramic reinforced hollow fiber membrane according to claim 3, characterized in that: The high-temperature melting temperature in S2 is set at 150-180°C, and the mixed inorganic ceramic powder is added to the membrane polymer powder and fed into the high-temperature melting equipment in a quantitative and sequential manner. The mixture is preheated before feeding using a waste heat recovery system provided outside the high-temperature melting equipment.

6. The method for preparing a ceramic reinforced hollow fiber membrane according to claim 3, characterized in that: The diameter of the inorganic ceramic powder / polymer composite fiber prepared by the melt spinning machine in S3 is set at 50μm-200μm, and the inorganic ceramic powder / polymer composite fiber prepared by melt spinning is collected after being cooled to room temperature by air in the form of side blowing, ring blowing and center blowing.

7. The method for preparing a ceramic reinforced hollow fiber membrane according to claim 3, characterized in that: The silicon carbide polymer used in S4 is prepared by directly mixing silicon carbide powder with a polymer resin, stirring and kneading the two to make them evenly dispersed, and then molding and curing to obtain a silicon carbide polymer composite material.

8. The method for preparing a ceramic reinforced hollow fiber membrane according to claim 3, characterized in that: In the S5, the outer surface of the fiber tube is firstly smoothed before coating with the homogeneous polymer casting liquid, and then a scraper or a coater is used for coating during the coating process, and the uniformity of the coating effect on the outer surface of the fiber tube is ensured, and after the coating operation is completed, the fiber tube is dried and solidified by a drying device, and the temperature of the drying device is controlled at 60-80°C.

9. The method for preparing a ceramic reinforced hollow fiber membrane according to claim 3, characterized in that: The phase inversion synchronization technique used in S6 comprises the following steps: S61, immersing the fiber tube coated with the homogeneous polymer casting solution in pure water for a certain period of time, so that the solvent and the non-solvent diffuse with each other. When the diffusion reaches a certain level, the homogeneous polymer casting solution becomes a thermodynamically unstable system, resulting in phase separation of the homogeneous polymer casting solution; S62. After the homogeneous polymer casting liquid system is separated into phases, the solvent and non-solvent are further exchanged, and the membrane pores are condensed, the phases flow, and the polymer-rich phase solidifies into a membrane, and finally a stable membrane is formed on the outside of the fiber tube.

10. The method for preparing a ceramic reinforced hollow fiber membrane according to claim 1, characterized in that: The membrane wall thickness of the membrane body (1) is set at 0.1-0.7 mm, and its inner diameter is set at 0.4-2.2 mm.

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