A PE-based material separation ultrafiltration membrane and its application

Abstract

This invention relates to the field of membrane material technology, specifically disclosing a PE-based material separation ultrafiltration membrane, and also its applications. The PE-based material separation ultrafiltration membrane provided by this invention is prepared through the following steps: taking a PE-based membrane, hydrophilically modifying the PE-based membrane to prepare a hydrophilic PE membrane; immersing the hydrophilic PE membrane in an aqueous solution, then removing it and drying it with cold air, followed by heat treatment; then immersing it in an oil-phase solution, followed by heat treatment, to obtain the PE-based material separation ultrafiltration membrane. The preparation process of the PE-based material separation ultrafiltration membrane provided by this invention is simple and low-cost, can be used to separate organic matter with a molecular weight greater than 700, and has the characteristics of high retention, good selective adsorption, and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of membrane materials technology, and in particular to a PE-based material separation ultrafiltration membrane, as well as its applications. Background Technology

[0002] Membrane separation technology combines the functions of separation, concentration, purification, and refining. It features high efficiency, energy saving, environmental protection, molecular-level filtration, and simple and easy-to-control filtration processes. It has significant advantages in drinking water purification, seawater desalination, treatment and disposal of urban sewage and industrial wastewater, as well as material separation, and has gained increasingly widespread attention.

[0003] Ultrafiltration membranes are a widely used and common membrane separation technology. The main characteristic of ultrafiltration membranes is that their pore size is between that of microfiltration and nanofiltration membranes, enabling them to retain substances with molecular weights ranging from hundreds to hundreds of thousands. They exhibit good separation effects on proteins, various alcohols, bacteria, viruses, and particulates. They have broad market prospects in wastewater treatment and material separation, and have attracted significant attention within the industry.

[0004] Currently, the market for ultrafiltration membrane materials mainly focuses on polysulfone (PSF), polyethersulfone (PES), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE), with no ultrafiltration membranes made of polyethylene (PE) yet to be found. Existing ultrafiltration membrane manufacturing processes are complex and costly, leading to a gradual decline in their competitive advantage.

[0005] Based on the above problems, the present invention aims to develop a new PE-based material separation ultrafiltration membrane to reduce the production cost of ultrafiltration membranes. Its application in water treatment and material separation fields will have a significant competitive advantage in the market. Summary of the Invention

[0006] The main technical problem solved by this invention is to provide an ultrafiltration membrane for separating PE-based materials, and also provides its applications.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a PE-based material separation ultrafiltration membrane, which is obtained by a preparation method comprising the following steps: S1. Take a PE base film and modify it to be hydrophilic to prepare a hydrophilic PE film. S2: Soak the hydrophilic PE membrane in an aqueous solution, then remove it and dry it with cold air, and then heat-bake it. S3: The PE membrane after step S2 is soaked in an oil phase solution, then taken out and heat-dried to prepare a PE-based material separation ultrafiltration membrane. The aqueous phase solution is an aqueous solution containing piperazine; the oil phase solution is a solution containing trimesoyl chloride.

[0008] As one embodiment of the present invention, the PE base film is prepared by a wet PE film preparation process, with a thickness of 9-20 μm and an average pore size of 30-50 nm.

[0009] Preferably, the thickness of the PE base film is 12-20 μm.

[0010] In one embodiment of the present invention, the hydrophilic modification uses PVA (polyvinyl alcohol) as the modifier.

[0011] Preferably, the molecular weight of the modifier PVA is 20,000 to 220,000.

[0012] As one embodiment of the present invention, the hydrophilic modification includes: coating the PE base film with a PVA solution to form a hydrophilic PE film.

[0013] Preferably, a PVA solution is coated on both sides of the PE base film to form a hydrophilic PE film.

[0014] Preferably, the mass percentage concentration of the PVA solution is 0.2% to 3%. More preferably, the mass percentage concentration of the PVA solution is 1% to 3%.

[0015] In one embodiment of the present invention, after coating the PE base film with a PVA solution, it is subjected to heat drying to form a hydrophilic PE film. The heat drying time is 1 to 5 minutes, and the heat drying temperature is 50°C to 60°C.

[0016] In one embodiment of the present invention, the aqueous solution is an aqueous solution of piperazine, wherein the mass percentage concentration of piperazine is 0.05% to 3%.

[0017] Preferably, the mass percentage concentration of piperazine in the aqueous solution is 1% to 3%.

[0018] In one embodiment of the present invention, the oil phase solution is a hexane solution of trimesoyl chloride, wherein the mass percentage concentration of trimesoyl chloride is 0.1% to 0.5%.

[0019] In one embodiment of the present invention, the soaking time in the aqueous solution is 1 to 60 minutes.

[0020] Preferably, the soaking time in the aqueous solution is 10–60 min.

[0021] In one embodiment of the present invention, the soaking time in the oil phase solution is 1 to 30 minutes.

[0022] Preferably, the soaking time in the oil phase solution is 1 to 15 minutes.

[0023] In one embodiment of the present invention, in step S2, the processing time of the hot drying treatment is 5 to 20 minutes, and the hot drying temperature is 50°C to 60°C.

[0024] In one embodiment of the present invention, in step S3, the processing time of the hot drying treatment is 5 to 20 minutes, and the hot drying temperature is 50°C to 60°C.

[0025] Secondly, the present invention provides an application of a PE-based material separation ultrafiltration membrane, wherein the PE-based material separation ultrafiltration membrane is used in material separation, concentration, purification and refining.

[0026] Thirdly, the present invention provides an application of a PE-based material separation ultrafiltration membrane in wastewater treatment.

[0027] The PE-based material separation ultrafiltration membrane provided by this invention is made from a polyethylene (PE) membrane. In recent years, due to the rapid development of the new energy industry, lithium-ion battery PE membranes have received increasing attention. With massive capital investment in the new energy industry, technological barriers are being continuously broken down. Along with the continuous updating of lithium-ion battery membrane production technology, the cost of lithium-ion battery PE membranes is rapidly decreasing. Therefore, using lithium-ion battery PE membranes as the base membrane to prepare PE-based material separation ultrafiltration membranes and applying them to water treatment and material separation fields will have a significant market competitive advantage.

[0028] The PE-based material separation ultrafiltration membrane provided by this invention has a simple preparation process and low cost. It can be used to separate organic matter with a molecular weight greater than 700 and has the characteristics of high retention, good selective adsorption and environmental friendliness. Attached Figure Description

[0029] Figure 1 This is the infrared spectrum of the PE-based material separation ultrafiltration membrane provided in Embodiment 1 of the present invention; Figure 2 This is a SEM image of the PE-based material separation ultrafiltration membrane provided in Embodiment 1 of the present invention; Figure 3 This is a SEM image of the PE-based material separation ultrafiltration membrane provided in Embodiment 2 of the present invention. Detailed Implementation

[0030] The technical solution of the present invention will be described in detail below through specific embodiments. These embodiments are intended to further illustrate the content of the present invention, but are not intended to limit the scope of protection of the claims of the present invention.

[0031] Unless otherwise specified, the materials or reagents used in the following embodiments or comparative examples of the present invention are all commercially available.

[0032] Example 1 This embodiment provides a PE-based material separation ultrafiltration membrane, which is obtained through a preparation method including the following steps: S1. Take a PE base film and perform hydrophilic modification on the PE base film. The modifier used for hydrophilic modification is PVA with a molecular weight of 200,000. Prepare a PVA solution with a mass percentage concentration of 1.5% by water. Roll the PVA solution onto both sides of the PE base film and then place it in an oven to bake at 60°C for 3 minutes to make a hydrophilic PE film. The PE base film was prepared using a wet PE film preparation process, with a thickness of 16μm and an average pore size of 45nm. S2: Soak the hydrophilic PE film in an aqueous phase solution, which is an aqueous solution of piperazine with a mass percentage concentration of 1% for 30 minutes. Then take it out and dry it with a hair dryer using cold air. Then place it in an oven for heat treatment for 10 minutes at a temperature of 60°C. S3: The PE membrane treated in step S2 is immersed in an oil phase solution, which is a hexane solution of trimesoyl chloride, wherein the mass percentage concentration of trimesoyl chloride is 0.3%, and the immersion time in the oil phase solution is 5 min. Piperazine and trimesoyl chloride polymerize, and their crosslinking products are uniformly attached to the membrane pores and membrane surface. Then, it is taken out and subjected to heat drying treatment for 15 min at a temperature of 60°C. After washing with water and drying, the PE-based material separation ultrafiltration membrane is prepared.

[0033] The PE-based material separation ultrafiltration membrane prepared in this embodiment has an average pore size of 29.6 nm and a maximum pore size of 41.2 nm.

[0034] The infrared spectrum of the PE-based material separation ultrafiltration membrane prepared in this embodiment is shown below. Figure 1 As shown, the SEM image is... Figure 2 As shown.

[0035] Figure 1 Infrared spectral analysis: (1) 1621 cm -1 (Measured value: 1613.468 cm) -1 ) Classification: Amide I band (C=O stretching vibration) Interpretation: Strong absorption peak, wavenumber significantly lower than 1700 cm⁻¹ for free C=O. -1 This indicates that amide bonds are formed and strong intermolecular hydrogen bonds exist (a characteristic of cross-linked polyamides). (2) 1575 cm -1 (The measured value is not directly marked, but it is 1560-1590 cm) -1 (The region has a corresponding peak) Classification: Amide II band (NH bending + CN stretching) Interpretation: It should appear in pairs with the amide I band, which is a characteristic double peak of polyamide; Based on the two main characteristic peaks above, the formation of amide bonds (-CO-NH-) can be determined.

[0036] Example 2 This embodiment provides a PE-based material separation ultrafiltration membrane, which is obtained through a preparation method including the following steps: S1. Take a PE base film and perform hydrophilic modification on the PE base film. The modifier used for hydrophilic modification is PVA with a molecular weight of 180,000. Prepare a PVA solution with a mass percentage concentration of 3% by water. Roll the PVA solution onto both sides of the PE base film and then place it in an oven to bake at 60°C for 5 minutes to make a hydrophilic PE film. The PE base film is prepared by a wet PE film preparation process, with a thickness of 10μm and an average pore size of 40nm. S2: Soak the hydrophilic PE film in an aqueous phase solution, which is an aqueous solution of piperazine with a mass percentage concentration of 3% for 50 minutes. Then take it out and dry it with a hair dryer using cold air. Then place it in an oven for heat treatment for 20 minutes at a temperature of 50°C. S3: The PE membrane treated in step S2 is immersed in an oil phase solution, which is a hexane solution of trimesoyl chloride, wherein the mass percentage concentration of trimesoyl chloride is 0.5%, and the immersion time in the oil phase solution is 15 min. Piperazine and trimesoyl chloride polymerize, and their crosslinking products are uniformly attached to the membrane pores and membrane surface. Then, it is taken out and subjected to heat drying treatment for 10 min at a temperature of 55°C. After washing with water and drying, the PE-based material separation ultrafiltration membrane is prepared.

[0037] The SEM image of the PE-based material separation ultrafiltration membrane prepared in this embodiment is shown below. Figure 3 As shown.

[0038] Comparative Example 1 This comparative example provides a PE-based ultrafiltration membrane. The difference between this comparative example and Example 1 is that in step S2, after taking it out and drying it with a hair dryer using cold air, it is not subjected to heat drying. Specifically, it is obtained through a preparation method including the following steps: S1. Take a PE base film and perform hydrophilic modification on the PE base film. The modifier used for hydrophilic modification is PVA with a molecular weight of 200,000. Prepare a PVA solution with a mass percentage concentration of 1.5% by water. Roll the PVA solution onto both sides of the PE base film and then place it in an oven to bake at 60°C for 3 minutes to make a hydrophilic PE film. The PE base film was prepared using a wet PE film preparation process, with a thickness of 16μm and an average pore size of 45nm. S2: Soak the hydrophilic PE membrane in an aqueous phase solution, which is an aqueous solution of piperazine with a mass percentage concentration of 1% for 30 minutes. Then remove it and dry it with a hair dryer using cold air. S3: The PE membrane treated in step S2 is immersed in an oil phase solution, which is a hexane solution of trimesoyl chloride, wherein the mass percentage concentration of trimesoyl chloride is 0.3%, and the immersion time in the oil phase solution is 5 min. After that, it is taken out and subjected to heat drying treatment for 15 min at a temperature of 60°C. Then, it is washed with water and dried to prepare a PE-based ultrafiltration membrane.

[0039] Effect Test Case The PE-based material separation ultrafiltration membrane provided in Example 1 was placed in an ultrafiltration device. A prepared 1000 mg / L Congo red solution was used as the feed liquid for ultrafiltration retention testing. The device was run at 0.3 MPa. After pre-pressurization for half an hour, the filtered liquid was taken out for concentration testing. The concentration of Congo red was 97 mg / L.

[0040] Calculations show that the PE-based material separation ultrafiltration membrane provided in Example 1 achieved a removal rate of 90.3% for Congo red solution with a molecular weight of 700 and a flux of 95 mLH. The experimental test results indicate that it achieved a very good retention effect.

[0041] The formula for calculating the removal rate is as follows: ; In the formula: V 进 V represents the concentration of Congo red in the feed solution. 出 This represents the concentration of Congo red in the filtered liquid.

[0042] The PE-based ultrafiltration membrane provided in Comparative Example 1 was placed in an ultrafiltration device. A prepared 1000 mg / L Congo red solution was used as the feed liquid for ultrafiltration rejection testing. The device was operated at 0.3 MPa. After pre-pressurization for half an hour, the filtered liquid was taken out for concentration testing, and the concentration of Congo red was 516 mg / L. Calculations showed that the PE-based material separation ultrafiltration membrane provided in Comparative Example 1 had a removal rate of 48.4% for a 700 molecular weight Congo red solution, indicating poor rejection performance.

[0043] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A PE-based material separation ultrafiltration membrane, characterized in that, Obtained by a preparation method including the following steps: S1. Take a PE base film and modify it to be hydrophilic to prepare a hydrophilic PE film. S2: Soak the hydrophilic PE membrane in an aqueous solution, then remove it and dry it with cold air, and then heat-bake it. S3: The PE membrane after step S2 is soaked in an oil phase solution, then taken out and heat-dried to prepare a PE-based material separation ultrafiltration membrane. The aqueous phase solution is an aqueous solution containing piperazine; the oil phase solution is a solution containing trimesoyl chloride.

2. The PE-based material separation ultrafiltration membrane according to claim 1, characterized in that, The PE base film has a thickness of 9-20 μm and an average pore size of 30-50 nm.

3. The PE-based material separation ultrafiltration membrane according to claim 1, characterized in that, The hydrophilic modification uses PVA as the modifier, and the molecular weight of PVA is 20,000 to 220,000.

4. The PE-based material separation ultrafiltration membrane according to claim 1 or 3, characterized in that, The hydrophilic modification includes: coating the PE base film with a PVA solution to form a hydrophilic PE film; the mass percentage concentration of the PVA solution is 0.2% to 3%.

5. The PE-based material separation ultrafiltration membrane according to claim 1, characterized in that, The aqueous solution is an aqueous solution of piperazine, with a mass percentage concentration of 0.05% to 3%.

6. The PE-based material separation ultrafiltration membrane according to claim 1, characterized in that, The oil phase solution is a hexane solution of pyromellitic chloride, with a mass percentage concentration of 0.1% to 0.5% for pyromellitic chloride.

7. The PE-based material separation ultrafiltration membrane according to claim 1, characterized in that, The soaking time in the aqueous phase solution is 1–60 min, and / or the soaking time in the oil phase solution is 1–30 min.

8. The PE-based material separation ultrafiltration membrane according to claim 1, characterized in that, In steps S2 and S3, the processing time for the hot drying treatment is 5 to 20 minutes, and the hot drying temperature is 50°C to 60°C.

9. The application of the PE-based material separation ultrafiltration membrane according to any one of claims 1-8 in material separation, concentration, purification and refining.

10. The application of the PE-based material separation ultrafiltration membrane according to any one of claims 1-8 in wastewater treatment.

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