Flame-retardant environment-friendly oil-water separation composite membrane based on tea polyphenol-silicon dioxide synergistic modification and preparation method of flame-retardant environment-friendly oil-water separation composite membrane
By synergistic modification of MCE membranes with tea polyphenols and silica, the problems of insufficient oil-water separation efficiency and flame retardant performance of MCE membranes were solved, achieving efficient and environmentally friendly oil-water separation, and improving the membrane's anti-fouling ability and flame retardant performance.
Patent Information
- Application Number
- CN202511145289.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-15
- Publication Date
- 2025-12-26
AI Technical Summary
Existing MCE membranes have shortcomings in oil-water separation efficiency and flame retardant properties, and traditional chemical modifiers may introduce toxicity risks, making it difficult to meet the requirements of green and environmentally friendly practices.
A synergistic modification method of tea polyphenols and silica was adopted. Hydrophilic silica powder was loaded onto the surface of TP-MCE membrane through vacuum filtration to form a dense barrier layer and physical barrier. Combined with the carbonization effect of tea polyphenols, the hydrophilicity and flame retardant properties of the membrane were improved, and the use of toxic substances was avoided through green modification process.
It achieves efficient oil-water separation, improves flame retardant performance, and the process is environmentally friendly and non-toxic. It has excellent anti-pollution ability and low cost characteristics, and is suitable for oil-water separation in high-risk environments.
Smart Images
Figure CN121198071A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of oil-water separation, and particularly relates to a flame-retardant environment-friendly oil-water separation composite membrane based on tea polyphenol-silicon dioxide synergistic modification and a preparation method thereof. BACKGROUND
[0002] With the acceleration of global industrialization, water pollution has become a core problem threatening ecological security and human sustainable development. Among them, improper handling of oil spills, oily wastewater discharge and industrial oil pollution mixtures is the key inducement leading to water pollution. Traditional oil-water separation technologies (such as flocculation method, flotation method, adsorption method, etc.) generally have the defects of low separation efficiency, high risk of secondary pollution and high energy consumption, which are difficult to meet the needs of green environmental protection and efficient treatment.
[0003] In recent years, separation membrane materials based on special wettability surface modification have attracted widespread attention due to their high efficiency and low energy consumption. Among them, nitrocellulose / acetic acid cellulose (MCE) membrane substrate has great potential in the field of oil-water separation due to its excellent biocompatibility, strong renewability and adjustable porous structure. However, the existing MCE membrane material still faces the following technical bottlenecks: firstly, the permeation flux and anti-pollution performance of single MCE membrane are limited, which is difficult to adapt to the separation needs of complex oil-water mixtures; secondly, the flame retardant performance of the membrane material is insufficient in high temperature or fire scene, which limits its actual application range; thirdly, traditional chemical modifiers (such as synthetic polymers) may introduce toxic risk, which does not meet the green development concept.
[0004] Hydrophilic silicon dioxide nanoparticles can significantly improve the hydrophilicity and permeation flux of membrane materials due to the rich siloxane groups and hydroxyl structures on their surface. Their unique flame-retardant mechanism (forming a silicon dioxide protective layer at high temperature) also provides a guarantee for the safety of the composite membrane. However, existing technologies mostly use silicon dioxide as an independent additive, which fails to fully exploit its synergistic effect with the membrane substrate.
[0005] On the other hand, tea polyphenol (TP) as a natural polyphenolic compound has strong adhesion, antioxidant and biological safety, and has been applied in medical dressing antibacterial coating. However, existing research has not paid attention to the potential value of TP in the integration of oil-water separation and flame retardant function, and the composite modification strategy of TP with inorganic nanoparticles and membrane substrate is still blank.
[0006] Therefore, how to realize efficient oil-water separation, flame retardant enhancement and environmental friendliness of MCE membrane through green modification has become a technical problem to be solved in the field. SUMMARY
[0007] The prior art has the problem that the oil-water separation effect of a single MCE membrane is poor. In view of the above technical problems, the present application provides a flame-retardant environmentally friendly oil-water separation composite membrane based on tea polyphenol-silicon dioxide synergistic modification, which is obtained by loading a water dispersion of hydrophilic silicon dioxide powder on the surface of a TP-MCE membrane by vacuum filtration, and then drying to obtain the composite membrane; the TP-MCE membrane is a membrane material obtained by TP impregnation modification of a microporous base membrane.
[0008] Preferably, the average particle size of the hydrophilic silicon dioxide powder is 20 nm.
[0009] Preferably, the microporous base membrane is a mixed cellulose ester microporous filter membrane.
[0010] Preferably, the pore size of the mixed cellulose ester microporous filter membrane is 0.45 μm.
[0011] Preferably, the method for TP impregnation modification of the microporous base membrane is to immerse the microporous base membrane in a water dispersion of tea polyphenol powder, after soaking (soaking time not less than 24 h), add a buffer to the immersion liquid to adjust the pH to 8, then take out the membrane material and dry to obtain a TP-MCE membrane.
[0012] Preferably, the loading amount of the hydrophilic silicon dioxide powder on the surface of the TP-MCE membrane is 8.33-41.7% of the mass of the TP-MCE membrane.
[0013] Preferably, the loading amount of the TP on the surface of the MCE membrane is 17.6% of the mass of the MCE membrane.
[0014] The present application has the following advantages: The tea polyphenol-silicon dioxide synergistically modified flame-retardant environmentally friendly oil-water separation composite membrane provided by the present application solves the core defects of flammability and easy pollution of traditional MCE membranes through a stepwise green modification process and synergistic design of natural / inorganic materials, and has the following significant advantages: (1) Double-effect flame-retardant mechanism: Tea polyphenol (TP) carbonizes to form a dense barrier layer at high temperature, blocking the diffusion of oxygen; Nanoscale SiO2 (20 nm) acts as a physical barrier to inhibit the release of flammable gas; Hydrophilic / oil-repellent underwater surface: SiO2 nanoparticles construct a micro-nano rough structure, making the water contact angle ≤60° (instantaneous wetting) and the underwater oil contact angle >135°; The TP coating enhances the surface hydrophilicity and synergistically inhibits the adhesion of oil droplets; (2) Oil-water separation capacity: The separation efficiency for emulsified oil-water mixture (such as diesel emulsion) is >95%, and the water flux is greater than 5300 L-2 -1 -2 -1 2 (3) Non-toxic modification process: -2 TP immersion only requires aqueous dispersion + pH adjustment (buffer to pH = 8), avoiding toxic crosslinking agents such as glutaraldehyde; -1 SiO2 is physically loaded by vacuum filtration, without introducing chemical bonding agents; 2 (4) Natural material dominant: TP as a bio-based modifier is naturally degradable, and SiO2 inorganic particles are environmentally friendly, and the overall process meets the principles of green chemistry; i (5) High gradient combination firmness: -2 TP forms multiple hydrogen bonds with MCE fibers through phenolic hydroxyl groups (immersion ≥ 24h to ensure penetration depth), with a loading capacity of 0.72g / cm²; -1 SiO2 is embedded in the TP coating pores by vacuum filtration, with a precise controllable loading capacity (1.99g / cm²) and no particle shedding; -2 (6) The present application uses a "TP chemical anchoring + SiO2 physical construction" synergistic strategy to give MCE membranes intrinsic flame retardant properties and long-term anti-pollution ability without significantly reducing their high flux advantage. Its green process design, excellent comprehensive performance, and low-cost characteristics provide a good solution for oil-water separation in high-risk environments (petrochemical, shipping). -1 BRIEF DESCRIPTION OF DRAWINGS
[0001] is a preparation process flowchart of the TP-MCE membrane of the present application.
[0002] is a preparation process flowchart of the TP@SiO2 membrane of the present application.
[0003]
[0004] is a scanning electron microscope image of MCE membrane, TP membrane, and M-5 membrane at different magnifications.
[0005] is the water contact angle and water flux, underwater oil contact angle, diesel emulsion flux and retention rate, and images before and after filtering diesel emulsion of M-1, M-2, M-3, M-4, and M-5 membranes obtained in Examples 1-5, respectively.
[0006] is the anti-pollution performance test image of MCE membrane, TP-MCE membrane, and M-5 membrane.
[0007]
[0008] is the combustion comparison of MCE membrane, TP-MCE membrane, and M-5 membrane. DETAILED DESCRIPTION
[0009] The application will be described in detail below in conjunction with examples. However, it should be understood that the following examples are only illustrative of the embodiments of the application, but not a limitation on the scope of the application.
[0022] The raw materials used in the application are as follows: The hydrophilic silicon dioxide powder with the product number Kg-SiO2-1 is purchased from Beijing Qinghe Metallurgical Materials Co., Ltd., and the average particle size is 20 nm.
[0023] The tea polyphenol is purchased from Shanghai Shifeng Biological Technology Co., Ltd., and the average particle size is 80 mesh.
[0024] The MCE membrane with the model number DL-NPMCE has a thickness of 0.16 mm, a diameter of 50 mm, and a pore size of 0.45 μm, and is purchased from Haining Defilter New Material Technology Co., Ltd.
[0025] The other raw materials or reagents used in the application are commercially available unless otherwise specified.
[0026] The TP@SiO2 membrane in the drawings of the specification of the application refers to the composite membrane after the hydrophilic silicon dioxide powder and the TP double-modified MCE membrane.
[0027] The preparation method of the TP-MCE membrane (the preparation process flow chart is shown in the specification) used in the application is as follows: Figure 1 At room temperature, the MCE membrane is soaked in the TP dispersion liquid for 24 h, and then dried in a 50℃ drying oven for 15 min after the soaking is completed, so that the loading amount of TP on the surface of the composite membrane is 17.6% of the mass of the MCE membrane; the preparation method of the TP dispersion liquid is as follows: The tea polyphenol powder is dispersed in deionized water to obtain a TP dispersion liquid with a mass concentration of 5 mg / mL, and a buffer Tris is used to adjust the pH of the TP dispersion liquid to 8.
[0028] Example 1
[0029] A preparation method of an environmentally friendly oil-water separation composite membrane based on tea polyphenol-silicon dioxide synergistic modification is as follows: (1) 5 mg of hydrophilic silicon dioxide powder is added to 50 mL of deionized water and ultrasonically dispersed to obtain a hydrophilic silicon dioxide dispersion liquid; (2) The hydrophilic silicon dioxide deposition liquid is loaded onto the surface of the TP-MCE membrane by vacuum filtration, and naturally dried at room temperature to obtain a composite membrane (the preparation process flow chart is shown in the specification), and the obtained composite membrane (the loading amount of the hydrophilic silicon dioxide powder on the surface of the composite membrane is 8.33% of the mass of the TP-MCE membrane) is named M-1. Figure 2
[0030] Example 2 is the same as Example 1 except that step (1) of Example 2 is to add 10 mg of hydrophilic silica powder into 50 mL of deionized water and ultrasonically disperse to obtain a hydrophilic silica dispersion. The obtained composite membrane (the loading amount of hydrophilic silica powder on the surface of the composite membrane is 16.7% of the mass of the TP-MCE membrane) is named M-2.
[0031] Example 3 is the same as Example 1 except that step (1) of Example 3 is to add 15 mg of hydrophilic silica powder into 50 mL of deionized water and ultrasonically disperse to obtain a hydrophilic silica dispersion. The obtained composite membrane (the loading amount of hydrophilic silica powder on the surface of the composite membrane is 25% of the mass of the TP-MCE membrane) is named M-3.
[0032] Example 4 is the same as Example 1 except that step (1) of Example 4 is to add 20 mg of hydrophilic silica powder into 50 mL of deionized water and ultrasonically disperse to obtain a hydrophilic silica dispersion. The obtained composite membrane (the loading amount of hydrophilic silica powder on the surface of the composite membrane is 33.3% of the mass of the TP-MCE membrane) is named M-4.
[0033] Example 5 is the same as Example 1 except that step (1) of Example 5 is to add 25 mg of hydrophilic silica powder into 50 mL of deionized water and ultrasonically disperse to obtain a hydrophilic silica dispersion. The obtained composite membrane (the loading amount of hydrophilic silica powder on the surface of the composite membrane is 41.7% of the mass of the TP-MCE membrane) is named M-5.
[0034] Comparative Example 1 is a TP-MCE membrane without modification by hydrophilic silica powder.
[0035] Performance Test
[0036] (1) Water contact angle: the contact angle formed by a water droplet and the surface of the membrane is tested by goniometry, when the contact angle is less than 90°, it is described as hydrophilic, when the contact angle is close to 0° or 0°, it is described as super-hydrophilic.
[0037] (2) Underwater oil contact angle: the contact angle formed by an underwater oil droplet and the surface of the membrane is tested by goniometry, when the contact angle is greater than 90°, it is described as oleophobic, when the contact angle is greater than 150°, it is described as super-oleophobic.
[0038] (3) Water flux test method: the water flux J of the membrane is determined by the speed of 100 mL of pure water passing through the composite membrane using a vacuum filtration device (vacuum pump pressure 0.08 MPa), the specific formula is: J = 100 mL / t .
[0039] J: water flux, unit: L m -2 h -1 , V: filtrate volume (L), A: effective membrane permeation area (m 2 ), Δt: filtration time (h).
[0040] (4) Oil permeation flux and oil retention rate test method: using a vacuum filtration device (vacuum pump pressure 0.08 MPa) to determine the oil permeation flux K of the composite membrane used to pass through 100 mL oil-in-water emulsion, the specific formula is: K= , wherein K is the oil permeation flux, unit: L m -2 h -1 , V: filtrate volume (L), A: effective membrane permeation area (m 2 ), Δt: filtration time (h).
[0041] Oil retention rate R: using a TOC tester to measure the oil concentration of the solution before and after separation, the specific formula is ; wherein C i (mg / L) and C0(mg / L) are the oil concentrations of the filtrate and the original oil-in-water emulsion, respectively, unit: mg / L.
[0042] The preparation method of the oil-in-water emulsion for testing is as follows: In a container, add 99 mL of deionized water and 1 mg of sodium dodecyl sulfate (as an emulsifier), then take 1 mL of diesel oil dyed with Sudan III and put it into the container containing 99 mL of deionized water, ultrasonic stirring for 30 min, and then magnetic stirring for 5 min to obtain a stable emulsion.
[0043] The test results are shown in Table 1.
[0044] Table 1 ,
[0045] Note: According to the existing data, it can be explained that MCE membrane and TP-MCE membrane cannot be directly used for oil-water separation, the effect is not ideal, and further modification of SiO2 is needed.
[0046] The description is attached Figure 3(a1-a3 are original MCE membranes, b1-b3 are TP-MCE membranes, c1-c3 are TP@SiO2 membranes) are scanning electron microscope images of MCE membranes, TP-MCE membranes and M-5 membranes at different magnifications. As can be seen from the figures, the honeycomb porous structure of the MCE membrane is conducive to the passage of water. After TP modification, the membrane pores are reduced, and the surface appears granular coating but little undulation. The composite membrane modified by aqueous silica has a structure with significant levels, rich micro-undulations and pores, which enhances the hydrophilicity, anti-pollution and mechanical strength, indicating that the surface of the water-based mixed fiber filter membrane is successfully modified.
[0047] Description Figure 4 (a) are the water contact angle and water flux diagrams of the composite membranes obtained in Examples 1-5, respectively; Figure 4 (b) are the underwater oil contact angle diagrams of the composite membranes obtained in Examples 1-5, respectively; Figure 4 (c) are the diesel emulsion flux and retention rate diagrams of the composite membranes obtained in Examples 1-5, respectively; Figure 4 (d) are the images of the composite membranes obtained in Examples 1-5 before and after filtering diesel emulsion (left side is after filtering, right side is before filtering).
[0048] From the description Figure 4 (a) It is observed that after the MCE membrane is modified by TP / SiO2, the water contact angles of M1-M3 membranes decrease to 39°, 33° and 25°, respectively, showing superhydrophilicity (M3 is the best); while the water contact angles of M4 and M5 membranes increase to 47° and 60°, respectively. The hydrophilicity first increases and then decreases (M3 is the boundary), which is due to the best hydrophilic performance of the surface of M3; the subsequent decrease is caused by the excessive SiO2 covering the tea polyphenol, reducing the surface roughness and making the membrane layer thicker and flatter.
[0049] From the description Figure 4 (b) It is observed that M1-M3 membranes only have underwater oleophobicity, while M4 and M5 membranes reach the standard of underwater superoleophobicity. By comparing the water contact angle results, it is found that the M3 membrane with the best hydrophilicity has the lowest underwater oil contact angle (135°) and the worst oleophobicity; the M5 membrane with poor hydrophilicity has the best oleophobicity (156°). This indicates that there is no certain correspondence between the hydrophilicity and the underwater oleophobicity of the membrane surface.
[0050] From the description Figure 4 (c) It is observed that the emulsion flux of M1 membrane is the highest (3737.9 L m -2 h -1 ), and then the flux continuously decreases to the lowest (1658.4 L m -2 h -1), although the flux decreased, the separation efficiency gradually increased, especially for M5.
[0051] Fig. 1 is a schematic diagram of the oil-water separation device according to the present application. Figure 4 (d) It was observed that the treated emulsion changed from red-white turbidity to clear transparency, which proved that the composite membrane had excellent diesel emulsion interception capacity, and TP / Si The success of the composite modification.
[0052] Fig. 2 is a schematic diagram of the oil-water separation device according to the present application. Figure 5 (a is the original MCE membrane, b is the TP-MCE membrane, and c is the TP@SiO2 membrane) is an oil pollution resistance test diagram of the MCE membrane, the TP-MCE membrane, and the M-5 membrane. The composite membrane has excellent oil-water separation capacity, and also exhibits excellent oil pollution resistance and self-cleaning performance. The experiment shows that: the original membrane is completely covered with dyed oil stains; the TP membrane is partially attached; and the composite membrane only slightly adheres to oil droplets and is easy to rinse clean. The original membrane and the TP membrane are permanently stained with oil, which proves that the pollution resistance of the composite membrane is significantly improved.
[0053] Fig. 3 is a schematic diagram of the oil-water separation device according to the present application. Figure 6 Fig. 4 is a combustion comparison diagram of the MCE membrane, the TP-MCE membrane, and the M-5 membrane. By observing the combustion phenomenon and time, it can be found that the flame-retardant effect of the composite membrane modified by TP alone does not change obviously, and the combustion time is only increased by 0.6s. The combustion time of the composite membrane modified by hydrophilic silicon dioxide and TP is increased to 2s.
[0054] The test result analysis shows that the M-5 membrane obtained in Example 5 is the oil-water separation composite membrane with the best performance.
[0055] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the contents of the specification, and must be determined according to the scope of the claims.
Claims
1. A flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica, characterized in that, The composite membrane is obtained by loading an aqueous dispersion of hydrophilic silica powder onto the surface of a TP-MCE membrane using vacuum filtration and then drying it; the TP-MCE membrane is a membrane material obtained by impregnating and modifying a microporous base membrane with TP.
2. The flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica according to claim 1, characterized in that, The average particle size of the hydrophilic silica powder is 20 nm.
3. The flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica according to claim 1, characterized in that, The microporous base membrane is a mixed cellulose ester microporous filter membrane.
4. The flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica as described in claim 3, characterized in that, The pore size of the mixed cellulose ester microporous filter membrane is 0.45 μm.
5. The flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica according to claim 1, characterized in that, The method of TP impregnation modification of microporous base membrane is to impregnate the microporous base membrane in an aqueous dispersion of tea polyphenol powder. After the impregnation is completed, a buffer is added to the impregnation solution to adjust the pH to 8. Then the membrane material is taken out and dried to obtain TP-MCE membrane.
6. The flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica according to claim 5, characterized in that, Soaking time should be no less than 24 hours.
7. The flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica according to claim 1, characterized in that, The hydrophilic silica powder is loaded onto the surface of the TP-MCE membrane at a rate of 41.7% of the TP-MCE membrane mass.
8. The flame-retardant and environmentally friendly oil-water separation composite membrane based on synergistic modification of tea polyphenols and silica according to claim 1, characterized in that, The loading of TP on the surface of the MCE membrane is 17.6% of the mass of the MCE membrane.
9. A method for separating oil and water, characterized in that, The flame-retardant and environmentally friendly oil-water separation composite membrane based on the synergistic modification of tea polyphenols and silica, as described in claims 1-8, is used for membrane separation of oil and water.