A method for preparing a hybrid ultrafiltration membrane

Abstract

The present invention discloses a method for preparing a hybrid ultrafiltration membrane, comprising the following steps: S1: preparing raw materials, collecting discarded SCR denitration catalyst (WSCR), and pre-treating the raw materials to obtain crude WSCR; S2: preparing WSCR powder, crushing the WSCR with a high-speed multifunctional grinder, grinding it with a mortar, and screening the powder after grinding with a sieve; S3: drying the powder, drying it in an oven to obtain dried WSCR powder, which is then packaged in a sealed bottle for later use. The present invention recycles discarded SCR denitration catalyst (WSCR), is simple and efficient, consumes little material, generates little waste liquid, is environmentally friendly, and has significant economic and environmental benefits. Hybridization can increase the specific surface area, hydrophilicity, and mechanical properties of the ultrafiltration membrane, giving the ultrafiltration membrane properties such as anti-fouling, high flux, and high retention rate.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrafiltration membranes, and in particular to a method for preparing a hybrid ultrafiltration membrane. Background Art

[0002] The widespread use of Selective Catalytic Reduction (SCR) technology generates a large amount of waste selective catalytic reduction (WSCR) catalyst. SCR is a widely used flue gas denitrification technology. Most catalysts use TiO2 as a carrier and V2O5 or V2O5-MoO3 as the active components. With increasing environmental protection efforts, the disposal of waste SCR denitrification catalysts (WSCR) generated from flue gas denitrification has attracted considerable attention. Spent vanadium-titanium denitrification catalysts, rich in elements such as V, W / Mo, and Ti, are considered hazardous waste, both polluting and valuable resources. Recycling these waste catalysts has significant economic and environmental benefits.

[0003] WSCR recovery technologies mainly include chlorination method, wet method and dry-wet combined method. Among them, the wet method can be divided into alkaline method and acid method, among which alkaline method recovery is the current mainstream recovery process; dry-wet combined method can be divided into sodium roasting, calcium roasting, potassium roasting, composite roasting, etc. The above regeneration and reuse methods have the disadvantages of large chemical consumption, high energy consumption and large amount of waste liquid generated, which cannot meet people's requirements. However, if they are used to prepare hybrid ultrafiltration membranes, they become a good choice. Summary of the Invention

[0004] The purpose of the present invention is to add WSCR to PVDF membrane and prepare hybrid ultrafiltration membrane by blending method, thereby improving the microstructure, hydrophilicity and anti-fouling performance of the membrane. A method for preparing a hybrid ultrafiltration membrane is proposed.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a hybrid ultrafiltration membrane comprises the following steps:

[0007] S1: Prepare raw materials, collect spent SCR denitration catalyst (WSCR), and pretreat it to obtain crude WSCR;

[0008] S2: Prepare WSCR powder by crushing it with a high-speed multifunctional grinder, grinding it with a mortar, and sieving it with a sieve to obtain the powder below the sieve;

[0009] S3: Drying: Place the obtained powder in an oven for drying to obtain dry WSCR powder, which is then placed in a sealed bottle for later use;

[0010] S4: Prepare dispersion A by adding 0, 0.21, 0.44, 0.70, 1.00, and 1.33 g of WSCR to N-dimethylacetamide (16.00 g each) and stirring and ultrasonically dispersing the mixture to obtain dispersion A;

[0011] S5: Prepare dispersion B by adding solution A to 0.5 g of polyvinyl pyrrolidone in a beaker, stirring and dispersing the mixture, and then subjecting the mixture to ultrasonic vibration for 1 hour to obtain dispersion B;

[0012] S6: preparing a casting solution, adding 4.00 g of polyvinylidene fluoride to dispersion B, stirring the mixture with a magnetic stirrer at room temperature for 20-30 hours to completely mix and dissolve the mixture, then placing the mixture in a vacuum drying oven at room temperature for vacuum degassing, and allowing the mixture to stand for 12-36 hours to obtain a casting solution;

[0013] S7: Prepare hybrid ultrafiltration membrane. First, pour the casting liquid onto a clean glass plate, then scrape the membrane with a 200um scraper, then pre-evaporate in air for 10 seconds, and then quickly put the glass plate into pure water for coagulation bath. After the membrane is completely solidified, soak it in deionized water to finally obtain a polyvinylidene fluoride hybrid ultrafiltration membrane. The membrane is stored in deionized water for maintenance.

[0014] As a further solution of the present invention: the pretreatment in S1 is performed by coarsely crushing the raw material, and impurities are screened out while crushing.

[0015] As a further solution of the present invention: the screening in S2 is performed through a 400-mesh sieve.

[0016] As a further solution of the present invention: in said S3, the temperature is controlled at 60° C. during oven drying, and the drying time is 2-24 hours.

[0017] As a further solution of the present invention: in S6, the polyvinylidene fluoride is pretreated before use and dried at 60° C. for 24 hours.

[0018] As a further solution of the present invention: in S7, the deionized water is used for soaking for no less than 12 hours, and the water is replaced every 8-14 hours.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention recycles discarded SCR denitration catalysts (WSCR), is simple and efficient, consumes little material, generates little waste liquid, is green and environmentally friendly, and has important economic value and environmental benefits.

[0021] 2. Organic-inorganic hybridization can improve the specific surface area, hydrophilicity and mechanical properties of the ultrafiltration membrane, so that the ultrafiltration membrane has the properties of anti-pollution, high flux and high retention rate, and has a good removal ability for humic acid.

[0022] 3. When preparing the hybrid ultrafiltration membrane, soak it in deionized water to remove a large amount of residual solvent DMAc and additives such as PVP in the membrane to improve its use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention provides a flow chart of a method for preparing a hybrid ultrafiltration membrane. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0025] Example 1

[0026] Reference Figure 1 , a method for preparing a hybrid ultrafiltration membrane, comprising the following steps:

[0027] S1: Prepare raw materials, collect waste SCR denitration catalysts (WSCR), and pretreat them to obtain crude WSCR. During the pretreatment in S1, the WSCR is coarsely crushed and impurities are screened out during the crushing;

[0028] S2: WSCR powder is prepared by crushing the WSCR with a high-speed multifunctional crusher, then grinding it with a mortar, and then screening the powder through a sieve. The present invention recycles the discarded SCR denitration catalyst (WSCR), is simple and efficient, has low material consumption, generates little waste liquid, is environmentally friendly, and has important economic value and environmental benefits. The screening in S2 is performed through a 400-mesh sieve;

[0029] S3: Drying: The obtained powder is placed in an oven for drying to obtain dry WSCR powder, which is then placed in a sealed bottle for later use. In S3, the temperature during oven drying is controlled at 60° C., and the drying time is 20 hours.

[0030] S4: Prepare dispersion A by adding 0, 0.21, 0.44, 0.70, 1.00, and 1.33 g of WSCR to N-dimethylacetamide (16.00 g each) and stirring and ultrasonically dispersing the mixture to obtain dispersion A;

[0031] S5: Prepare dispersion B by adding solution A to 0.5 g of polyvinyl pyrrolidone in a beaker, stirring and dispersing the mixture, and then subjecting the mixture to ultrasonic vibration for 1 hour to obtain dispersion B;

[0032] S6: preparing a casting solution, adding 4.00 g of polyvinylidene fluoride to dispersion B, stirring the solution with a magnetic stirrer at room temperature for 24 hours to completely mix and dissolve the solution, then placing the solution in a vacuum drying oven at room temperature for vacuum degassing, and standing the solution for 24 hours to obtain a casting solution. In S6, the polyvinylidene fluoride was pretreated before use and dried at 60°C for 24 hours;

[0033] S7: Prepare hybrid ultrafiltration membrane. First, pour the casting liquid onto a clean glass plate, then use a 200um scraper to scrape the membrane, then pre-evaporate in the air for 10 seconds, and then quickly place the glass plate in pure water for coagulation bath. After the membrane is completely solidified, soak it in deionized water to finally obtain a polyvinylidene fluoride hybrid ultrafiltration membrane. The membrane is stored in deionized water for maintenance. The organic-inorganic hybridization can improve the specific surface area, hydrophilicity and mechanical properties of the ultrafiltration membrane, so that the ultrafiltration membrane has anti-pollution, high flux and high retention rate, and has good removal ability for humic acid. Soak in deionized water for no less than 12 hours in S7, and replace the water every 13 hours to remove a large amount of solvent DMAc and PVP and other additives remaining in the membrane.

[0034] Example 2

[0035] Reference Figure 1 , a method for preparing a hybrid ultrafiltration membrane, comprising the following steps:

[0036] S1: Prepare raw materials, collect waste SCR denitration catalysts (WSCR), and pretreat them to obtain crude WSCR. During the pretreatment in S1, the WSCR is coarsely crushed and impurities are screened out during the crushing;

[0037] S2: WSCR powder is prepared by crushing the WSCR with a high-speed multifunctional crusher, then grinding it with a mortar, and then screening the powder through a sieve. The present invention recycles the discarded SCR denitration catalyst (WSCR), is simple and efficient, has low material consumption, generates little waste liquid, is environmentally friendly, and has important economic value and environmental benefits. The screening in S2 is performed through a 400-mesh sieve;

[0038] S3: Drying: The obtained powder is placed in an oven for drying to obtain dry WSCR powder, which is then placed in a sealed bottle for later use. In S3, the temperature during oven drying is controlled at 60° C., and the drying time is 18 hours.

[0039] S4: Prepare dispersion A by adding 0, 0.21, 0.44, 0.70, 1.00, and 1.33 g of WSCR to N-dimethylacetamide (16.00 g each) and stirring and ultrasonically dispersing the mixture to obtain dispersion A;

[0040] S5: Prepare dispersion B by adding solution A to 0.5 g of polyvinyl pyrrolidone in a beaker, stirring and dispersing the mixture, and then subjecting the mixture to ultrasonic vibration for 1 hour to obtain dispersion B;

[0041] S6: preparing a casting solution, adding 4.00 g of polyvinylidene fluoride to dispersion B, stirring the solution with a magnetic stirrer at room temperature for 24 hours to completely mix and dissolve the solution, then placing the solution in a vacuum drying oven at room temperature for vacuum degassing, and standing the solution for 26 hours to obtain a casting solution. In S6, the polyvinylidene fluoride was pretreated before use and dried at 60°C for 24 hours;

[0042] S7: Prepare hybrid ultrafiltration membrane. First, pour the casting liquid onto a clean glass plate, then use a 200um scraper to scrape the membrane, then pre-evaporate in the air for 10 seconds, and then quickly put the glass plate into pure water for coagulation bath. After the membrane is completely solidified, soak it in deionized water to finally obtain a polyvinylidene fluoride hybrid ultrafiltration membrane. The membrane is stored in deionized water for maintenance. The organic-inorganic hybridization can improve the specific surface area, hydrophilicity and mechanical properties of the ultrafiltration membrane, so that the ultrafiltration membrane has anti-pollution, high flux and high retention rate, and has good removal ability for humic acid. Soak in deionized water for at least 12 hours in S7, and replace the water every 12 hours to remove a large amount of solvent DMAc and PVP and other additives remaining in the membrane.

[0043] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a hybrid ultrafiltration membrane, comprising the following steps: S1: Prepare raw materials, collect spent SCR denitration catalyst (WSCR), and pretreat it to obtain crude WSCR; S2: Prepare WSCR powder by crushing it with a high-speed multifunctional grinder, grinding it with a mortar, and sieving it with a sieve to obtain the powder below the sieve; S3: Drying: placing the obtained powder in an oven for drying to obtain dry WSCR powder, which is then placed in a sealed bottle for later use; S4: Prepare dispersion A by adding 0.21, 0.44, 0.70, 1.00, and 1.33 g of WSCR to N-dimethylacetamide (16.00 g each) and stirring and ultrasonically dispersing the mixture to obtain dispersion A; S5: Prepare dispersion B by adding solution A to 0.5 g of polyvinyl pyrrolidone in a beaker, stirring and dispersing the mixture, and then subjecting the mixture to ultrasonic vibration for 1 h to obtain dispersion B; S6: preparing a casting solution, adding 4.00 g of polyvinylidene fluoride to dispersion B, stirring the mixture with a magnetic stirrer at room temperature for 20-30 hours to completely mix and dissolve the mixture, then placing the mixture in a vacuum drying oven at room temperature for vacuum degassing, and allowing the mixture to stand for 12-36 hours to obtain a casting solution; S7: Prepare hybrid ultrafiltration membrane. First, pour the casting liquid onto a clean glass plate, then scrape the membrane with a 200um scraper, then pre-evaporate in air for 10 seconds, and then quickly put the glass plate into pure water for coagulation bath. After the membrane is completely solidified, soak it in deionized water to finally obtain a polyvinylidene fluoride hybrid ultrafiltration membrane. The membrane is stored in deionized water for maintenance.

2. The method for preparing a hybrid ultrafiltration membrane according to claim 1, characterized in that: The pretreatment in S1 is to coarsely crush the raw material and screen out impurities while crushing.

3. The method for preparing a hybrid ultrafiltration membrane according to claim 2, characterized in that: The sieving in S2 is performed through a 400-mesh sieve.

4. The method for preparing a hybrid ultrafiltration membrane according to claim 1, characterized in that: In the step S3, the temperature during oven drying is controlled at 60° C., and the drying time is 2-24 hours.

5. The method for preparing a hybrid ultrafiltration membrane according to claim 4, characterized in that: In the S6, the polyvinylidene fluoride is pretreated before use and dried at 60° C. for 24 hours.

6. The method for preparing a hybrid ultrafiltration membrane according to claim 1, characterized in that: In the step S7, the sample is immersed in deionized water for no less than 12 hours, and the water is replaced every 8-14 hours.

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