Difunctional ultrafiltration membrane and preparation method thereof
By using a dual-function ultrafiltration membrane in photovoltaic wastewater treatment, the composition includes manganese dioxide nanoparticles and polymers, combined with alkaline earth metal inorganic nanoparticles or acidic functional organic compounds, forming a dense cortex and sponge pore structure, the hydrogen peroxide in photovoltaic wastewater and The problem of particulate matter removal extends the life of the membrane and reduces operation and maintenance costs.
Patent Information
- Application Number
- CN202411559275.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-04
- Publication Date
- 2024-12-20
AI Technical Summary
The high concentration of hydrogen peroxide in existing photovoltaic production wastewater leads to reverse osmosis or oxidation and decomposition of nanofiltration membranes, thereby reducing reuse and increasing operation and maintenance costs. In addition, traditional removal methods such as manganese sand filtration and reducing agent filtration have colloid blockage and high cost. The problem.
Using a dual-function ultrafiltration membrane, the composition includes manganese dioxide nanoparticles and polymers, and water-insoluble alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups are added to the polymer, and the mixture is stirred and gel bath. Form a dense cortex and a uniform sponge pore structure to achieve the removal of hydrogen peroxide and particulate matter.
Effectively reduce the effluent oxide content, extend the life of downstream membranes, reduce operation and maintenance costs, improve wastewater reuse rate, and avoid colloid blockage and reducing agent consumption.
Smart Images
Figure CN119158414A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a dual-function ultrafiltration membrane and a preparation method thereof. Background Art
[0002] The amount of water and wastewater in the production process is also considerable. At present, the annual water demand for photovoltaic production in China exceeds 500 million tons, and 300 million tons of wastewater are discharged, which brings great environmental pressure to enterprises and local areas. At the same time, photovoltaic wastewater has extremely high requirements for water treatment technology, mainly because the wastewater is highly acidic, alkaline and oxidizing; the wastewater has poor biodegradability; the quality and quantity of wastewater discharged in different production processes and time periods vary greatly; environmental protection regulations continue to raise standards for fluoride ion emissions.
[0003] The concentration of hydrogen peroxide in photovoltaic wastewater is generally around tens to hundreds of ppm. This is mainly because hydrogen peroxide is mainly used for cleaning and etching photovoltaic cells and is an important raw material for configuring cell cleaning fluid. However, nanofiltration and reverse osmosis membranes, key technologies for wastewater reuse, are intolerant to oxidizing substances. They require the content of oxidizing substances in the influent to be less than 0.1ppm, otherwise the separation functional layer with a thickness of only tens of nanometers will undergo oxidative decomposition, resulting in a sharp drop in separation efficiency. Therefore, membrane separation technology is rarely used for photovoltaic wastewater at present, and simple mixing and sedimentation technology is mainly used, with a recovery rate of only 30%.
[0004] In order to achieve efficient use and protection of water resources, it has become an important trend to use membrane separation technology in photovoltaic wastewater treatment to increase wastewater reuse rate. This requires adding a hydrogen peroxide removal device before reverse osmosis or nanofiltration water inlet.
[0005] Compared with traditional manganese sand filtration, the dissolution of manganese sand will not only increase the salt concentration of the effluent, but the iron ions and manganese ions in it will enter the downstream reverse osmosis system with the effluent, and gradually form colloids during the circulation process, eventually clogging the membrane or precision filtration device, resulting in flux attenuation and the need for frequent cleaning.
[0006] Compared with traditional reducing agent filtration, reducing agents such as sodium bisulfite are used. However, unlike the principle of manganese dioxide catalyzing the decomposition of hydrogen peroxide, reducing agents are consumables and need to be added in equivalent amounts to achieve the effect. The cost is high, and the amount added and the hydrogen peroxide content of the influent need to be monitored in real time to prevent the addition of too much or too little.
[0007] Therefore, in order to solve the problems of colloid blockage caused by manganese sand in removing hydrogen peroxide and fast failure of adding reducing agent, which makes it difficult to use it for a long time, a dual-function ultrafiltration membrane and a preparation method thereof are provided. Summary of the invention
[0008] The purpose of the present invention is to overcome the existing defects and provide a dual-function ultrafiltration membrane and a preparation method thereof, which can remove hydrogen peroxide and particulate matter in one step through the dual-function ultrafiltration membrane, ensure that the oxide content in the effluent is lower than the limit of the reverse osmosis or nanofiltration membrane, and realize the long life of the downstream separation membrane.
[0009] The technical solution to achieve the above purpose is: One of the present invention is a dual-function ultrafiltration membrane, characterized in that the dual-function ultrafiltration membrane comprises the following components: manganese dioxide nanoparticles and polymers, and also includes water-insoluble alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups added to the polymers; The dual-function ultrafiltration membrane comprises the following components by weight: The polymer is based on 100 parts by weight: 10-300 parts of manganese dioxide nanoparticles; 1-20 parts of alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups.
[0010] Preferably, the particle size of the manganese dioxide nanoparticles is 5nm-5um.
[0011] Preferably, the polymer is an ultrafiltration membrane material, including but not limited to polysulfone, polyethersulfone, polyphenylsulfone, polyacrylonitrile and polyvinylidene fluoride.
[0012] Preferably, alkaline earth metal inorganic nanoparticles include but are not limited to magnesium oxide, magnesium hydroxide, barium sulfate and hydroxyapatite, and functional organic substances with acidic groups include but are not limited to sulfonated polysulfone, sulfonated polyether sulfone, sulfonated polyphenyl sulfone, maleic acid and polystyrene copolymers of polymers, and sodium stearate, acetic acid, butyric acid, malic acid and polyphosphoric acid of small molecules.
[0013] A second method for preparing a dual-function ultrafiltration membrane of the present invention comprises: Step S1, mixing manganese dioxide nanoparticles and alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups in DMF by high-speed stirring; Step S2, adding a polymer to the mixed solution prepared above; Step S3, subjecting the mixed solution to high-speed stirring and degassing for 12 hours to form a uniform composite slurry; Step S4, coating the uniform composite slurry on a non-woven fabric and placing it in a gel bath to form a dual-function ultrafiltration membrane containing manganese dioxide particles.
[0014] Preferably, in step S4, the gel bath is an aqueous solution of a dipolar aprotic solvent, and the dipolar aprotic solvent includes but is not limited to N-methylpyrrolidone, N,N-dimethylformamide, and N,N-diethylformamide; wherein the weight percentage of the dipolar aprotic solvent in the aqueous solution ranges from 1% to 30%.
[0015] Preferably, in the step S4, in the formed dual-function ultrafiltration membrane, the weight of water-insoluble alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups accounts for 1%-20% of the total solids.
[0016] The beneficial effects of the present invention are as follows: the dual-function ultrafiltration membrane of the present invention can effectively protect the reverse osmosis or nanofiltration membrane in the dual-membrane process for photovoltaic wastewater treatment, while removing particulate matter and hydrogen peroxide, and will not dissolve multivalent cations that are easy to form colloids or salts that increase conductivity, thereby preventing back-end membrane fouling and oxidative decomposition; compared with traditional manganese sand filtration or reducing agent filtration, the present invention saves costs, reduces space occupancy, and simplifies the operation and maintenance process. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a flow chart of a method for preparing a dual-function ultrafiltration membrane of the present invention; Figure 2 This is a schematic diagram of the SEM microstructure of the surface cortex of the dual-function ultrafiltration membrane of the present invention; Figure 3 It is a schematic diagram of the SEM microstructure of the cross-section cortex of the dual-function ultrafiltration membrane of the present invention. DETAILED DESCRIPTION
[0018] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.
[0019] The present invention will be further described below in conjunction with the accompanying drawings.
[0020] A dual-function ultrafiltration membrane, characterized in that the dual-function ultrafiltration membrane comprises the following components: manganese dioxide nanoparticles and polymers, and also comprises water-insoluble alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups added to the polymers; The dual-function ultrafiltration membrane comprises the following components by weight: The polymer is based on 100 parts by weight: 10-300 parts of manganese dioxide nanoparticles; 1-20 parts of alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups.
[0021] In the embodiment, the particle size of the manganese dioxide nanoparticles is 5nm-5um; preferably between 10nm-300nm, and the manganese dioxide nanoparticles with a specific surface area of 5-1000m2 / g are selected, specifically 20-200m2 / g.
[0022] In the embodiment, the polymer is an ultrafiltration membrane material, including but not limited to polysulfone, polyethersulfone, polyphenylsulfone, polyacrylonitrile and polyvinylidene fluoride.
[0023] In the embodiment, in order to improve the stability of manganese dioxide in the dual-function ultrafiltration membrane, water-insoluble alkaline earth metal inorganic nanoparticles are added to the polymer; the alkaline earth metal inorganic nanoparticles include but are not limited to magnesium oxide, magnesium hydroxide, barium sulfate and hydroxyapatite; after the alkaline earth metal inorganic nanoparticles and the polymer form a film, the powder falling phenomenon is greatly reduced, and the pores are denser.
[0024] Another method to improve the stability of manganese dioxide particles is to add functional organic substances with acidic groups to the polymer system; functional organic substances with acidic groups include but are not limited to sulfonated polysulfone, sulfonated polyethersulfone, sulfonated polyphenylsulfone, maleic acid and polystyrene copolymers of macromolecules, and sodium stearate, acetic acid, butyric acid, malic acid and polyphosphoric acid of small molecules; organic acid groups can form strong coordination bonds with manganese, which is conducive to the uniform dispersion of manganese dioxide nanoparticles in the polymer matrix. Functional organic substances with acidic groups can form strong coordination bonds with manganese, which is conducive to the uniform dispersion of manganese dioxide nanoparticles in the polymer matrix.
[0025] like Figure 1 As shown, a method for preparing a dual-function ultrafiltration membrane comprises: Step S1, mixing manganese dioxide nanoparticles and alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups in DMF by high-speed stirring.
[0026] Step S2, adding a polymer to the mixed solution prepared above.
[0027] Step S3, the mixed solution is subjected to high-speed stirring and degassing for 12 hours to form a uniform composite slurry.
[0028] Step S4, coating the uniform composite slurry on a non-woven fabric and placing it in a gel bath to form a dual-function ultrafiltration membrane containing manganese dioxide particles, such as Figure 2 , 3As shown, by regulating the phase conversion process, a dense cortex can be formed on the surface of the dual-function ultrafiltration membrane to filter out particulate matter, while uniform sponge pores are formed inside the membrane, and manganese dioxide particles are distributed on the surface of the water channel to achieve the catalytic decomposition of hydrogen peroxide.
[0029] In the embodiment, the gel bath is a dipolar aprotic solvent aqueous solution, and the dipolar aprotic solvent includes but is not limited to N-methylpyrrolidone, N,N-dimethylformamide, and N,N-diethylformamide; wherein the weight percentage of the dipolar aprotic solvent in the aqueous solution ranges from 1% to 30%.
[0030] In the embodiment, in the formed dual-functional ultrafiltration membrane, the weight of the water-insoluble alkaline earth metal inorganic nanoparticles or the functional organic matter with acidic groups accounts for 1%-20% of the total solids.
[0031] The following experiments were conducted to verify the ability of the dual-function ultrafiltration membrane of the present invention to remove hydrogen peroxide and particulate matter.
[0032] Comparative example: 18% polyethersulfone and N,N-dimethylformamide (DMF) solution were prepared to form a mixed solution, which was then precisely coated on a non-woven fabric. The gel bath was an 8% DMF aqueous solution, and the temperature was controlled at 15 degrees Celsius. After multiple steps of cleaning, a polyethersulfone ultrafiltration membrane was formed. The ultrafiltration layer had a thickness of approximately 50um, a molecular weight cutoff of 100,000 Da, and a pure water flux of 567LMH / bar.
[0033] Example 1: Manganese dioxide nanoparticles (50nm), polysulfone, and DMF mixed solution were prepared with a weight ratio of 1.5:16.5:82. After 12 hours of high-speed stirring and degassing, a uniform composite slurry was formed, which was precisely coated on a non-woven fabric. The gel bath was a 12% DMF aqueous solution, and the temperature was controlled at 15 degrees Celsius to form a mixed matrix ultrafiltration membrane containing manganese dioxide particles. The ultrafiltration layer thickness is about 50um, the molecular weight cutoff is 100,000 Da, and the pure water flux is 461LMH / bar.
[0034] Example 2: Manganese dioxide nanoparticles (50nm), polysulfone, and DMF mixed solution were prepared with a weight ratio of 12.6:5.4:82. After 12 hours of high-speed stirring and degassing, a uniform composite slurry was formed, which was precisely coated on a non-woven fabric. The gel bath was a 12% DMF aqueous solution, and the temperature was controlled at 15 degrees Celsius to form a mixed matrix ultrafiltration membrane containing manganese dioxide particles. The ultrafiltration layer thickness is about 50um, the molecular weight cutoff is 100,000 Da, and the pure water flux is 271LMH / bar.
[0035] Example 3: Manganese dioxide nanoparticles (50nm), polyethersulfone, and DMF mixed solution were prepared at a weight ratio of 18:12:70. After 12 hours of high-speed stirring and degassing, a uniform composite slurry was formed, which was precisely coated on a non-woven fabric. The gel bath was a 15% DMF aqueous solution, and the temperature was controlled at 15 degrees Celsius to form a mixed matrix ultrafiltration membrane containing manganese dioxide particles. The ultrafiltration layer thickness is about 50um, the molecular weight cutoff is 20,000 Da, and the pure water flux is 112LMH / bar.
[0036] Example 4: Manganese dioxide nanoparticles (50nm), sulfonated polysulfone (20% sulfonation degree), polyethersulfone, and DMF mixed solution were prepared with a weight ratio of 18:1.5:10.5:70. After 12 hours of high-speed stirring and degassing, a uniform composite slurry was formed and precisely coated on a non-woven fabric. The gel bath was a 15% DMF aqueous solution, and the temperature was controlled at 15 degrees Celsius to form a mixed matrix ultrafiltration membrane containing manganese dioxide particles. The ultrafiltration layer thickness is about 50um, the molecular weight cutoff is 20,000 Da, and the pure water flux is 183LMH / bar.
[0037] Hydrogen peroxide removal experiment: A 100ppm hydrogen peroxide solution was prepared, the pH was controlled between 8-9, the temperature was 25 degrees Celsius, and the above comparative examples and examples 1-4 were all rolled into 1812 standard membrane elements; the ultrafiltration operating pressure was 0.1Mpa, the recovery rate was 90%, and hydrogen peroxide spiked test water was introduced. After the flow rate was stable for 30 minutes, the hydrogen peroxide content of the effluent was tested. The results are shown in Table 1 below:
[0038] In the comparative example, conventional ultrafiltration membranes basically do not remove hydrogen peroxide, while the dual-function mixed matrix membrane can effectively remove hydrogen peroxide. When the manganese dioxide content is increased to a certain level (such as Example 2-4), the hydrogen peroxide concentration is reduced to the limit of 0.1ppm, which meets the reverse osmosis membrane inlet water requirements. It is also found that the addition of hydrophilic sulfonated polymers can increase the membrane flux without reducing the removal efficiency, which may be because the sulfonated groups can more effectively and evenly disperse the manganese dioxide nanoparticles, making the effective catalytic area of the water channel higher.
[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A dual-function ultrafiltration membrane, characterized in that: The dual-function ultrafiltration membrane comprises the following components: manganese dioxide nanoparticles and polymers, and also water-insoluble alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups added into the polymers; The dual-function ultrafiltration membrane comprises the following components by weight: The polymer is based on 100 parts by weight: 10-300 parts of manganese dioxide nanoparticles; 1-20 parts of alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups.
2. A dual-function ultrafiltration membrane according to claim 1, characterized in that: The particle size of manganese dioxide nanoparticles is 5nm-5um.
3. A dual-function ultrafiltration membrane according to claim 1, characterized in that: Polymers are ultrafiltration membrane materials, including but not limited to polysulfone, polyethersulfone, polyphenylsulfone, polyacrylonitrile and polyvinylidene fluoride.
4. A dual-function ultrafiltration membrane according to claim 1, characterized in that: Alkaline earth metal inorganic nanoparticles include but are not limited to magnesium oxide, magnesium hydroxide, barium sulfate and hydroxyapatite, and functional organic substances with acidic groups include but are not limited to polymers such as sulfonated polysulfone, sulfonated polyether sulfone, sulfonated polyphenyl sulfone, maleic acid and polystyrene copolymers, and small molecules such as sodium stearate, acetic acid, butyric acid, malic acid and polyphosphoric acid.
5. A method for preparing a dual-function ultrafiltration membrane, characterized in that: include: Step S1, mixing manganese dioxide nanoparticles and alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups in DMF by high-speed stirring; Step S2, adding a polymer to the mixed solution prepared above; Step S3, subjecting the mixed solution to high-speed stirring and degassing for 12 hours to form a uniform composite slurry; Step S4, coating the uniform composite slurry on a non-woven fabric and placing it in a gel bath to form a dual-function ultrafiltration membrane containing manganese dioxide particles.
6. The method for preparing a dual-function ultrafiltration membrane according to claim 5, characterized in that: In step S4, the gel bath is an aqueous solution of a dipolar aprotic solvent, and the dipolar aprotic solvent includes but is not limited to N-methylpyrrolidone, N,N-dimethylformamide, and N,N-diethylformamide; wherein the weight percentage of the dipolar aprotic solvent in the aqueous solution ranges from 1% to 30%.
7. The method for preparing a dual-function ultrafiltration membrane according to claim 5, characterized in that: In the step S4, in the formed dual-function ultrafiltration membrane, the weight of water-insoluble alkaline earth metal inorganic nanoparticles or functional organic matter with acidic groups accounts for 1%-20% of the total solids.