A rapid green and good versatility polyphenol coating modification method, product and application thereof

Abstract

The application discloses a kind of fast green and good versatility polyphenol coating modification method, product and application thereof.Hydrophobic material is washed with ethanol multiple times to be pre-wetted;Pre-wetted hydrophobic material is immersed in polyphenol-containing substance, silane coupling agent with amino group and deionized water to be super-hydrophilic modified;Modified film is taken out and washed with deionized water completely.The prepared polyphenol coating modified super-hydrophilic film has layered nanosphere structure, and can be applied to purification of oily wastewater.The method is carried out in pure water system, does not contain any toxic additives and oxidant, and only needs 40 minutes to realize super-hydrophilic modification of various polymer hydrophobic films, greatly improves modification efficiency.Modified PP film prepared by the method has super-high pure water flux and higher oil-in-water emulsion separation efficiency, and has excellent mechanical stability, acid and alkali resistance and long-term stability in air.The method has the advantages of green environmental protection, good versatility, high modification efficiency and the like.

Description

Technical Field

[0001] This invention belongs to the field of material modification technology, specifically relating to a rapid, green, and universally applicable method for modifying polyphenol coatings, the products thereof, and their applications. Background Technology

[0002] With rapid economic development, industrial production and daily life generate a large amount of oily wastewater, most of which exists in the form of oil-in-water emulsions. These emulsified oils are often difficult to treat, severely damaging the ecological environment and affecting people's lives. Therefore, there is an urgent need for efficient oil-water separation technology to treat oily wastewater and purify water resources. Conventional methods for treating oily wastewater include gravity separation, ultrasonic separation, centrifugation, and coagulation-based biological treatment. However, these methods suffer from low separation efficiency, complex processes, and secondary pollution. Membrane separation technology, on the other hand, has advantages such as simplicity and high separation efficiency, and has been widely used in water treatment. Currently, some membrane materials, such as polyvinylidene fluoride (PVDF), polypropylene (PP), and polytetrafluoroethylene (PTFE), are hydrophobic. Direct use in oil-water separation can adsorb oil droplets and proteins from the oil-in-water emulsion, causing membrane fouling and significantly reducing separation efficiency. Therefore, superhydrophilic modification of these hydrophobic membranes is an effective way to solve the membrane fouling problem. In recent years, due to their wide applicability and multifunctionality, polyphenol coatings have received widespread attention for surface modification of separation membranes, especially for rapid modification. For example, patent application CN112029146A discloses a superhydrophobic coating based on protein particles and its preparation method; patent application CN114515515 discloses a superhydrophobic hollow MOFs modified hollow fiber composite membrane and its application; CN114425508A discloses a metal material with a superhydrophobic surface, its preparation method and application, and an oil-water separation method; CN105064040A discloses a method for hydrophilic modification of the surface of porous hydrophobic materials. All of these disclose coating modification based on polyphenols and silane coupling agents. However, these coating modification methods suffer from drawbacks such as complex processes, long processing times, and secondary pollution. Furthermore, to improve modification efficiency and shorten the formation time of the polyphenol coating, some toxic oxidants (such as H2O2, CuSO4, NaIO4, etc.) are inevitably added during the modification process. The introduction of these oxidants leads to secondary pollution during preparation. Therefore, developing a rapid, green, and universally applicable coating modification strategy remains a significant challenge. Summary of the Invention

[0003] To address the issue of existing technologies failing to simultaneously achieve high modification efficiency and environmental friendliness, this invention aims to provide a rapid, green, and universally applicable method for polyphenol coating modification. This method facilitates the rapid superhydrophilic modification of various hydrophobic membranes, enabling efficient separation of oil-in-water emulsions. Using polyphenols and silane coupling agents with amino groups as raw materials, the concentration ratio and reaction rate are controlled, significantly shortening the polyphenol coating formation time and improving the modification efficiency of hydrophobic membranes. Furthermore, the modification process is green and environmentally friendly, conducted in a pure water system without any toxic additives or oxidants. Superhydrophilic modification of various polymer hydrophobic membranes, such as polypropylene (PP), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE), can be achieved in just 40 minutes, demonstrating excellent versatility. Therefore, our polyphenol coating modification strategy not only improves modification efficiency but also solves the secondary pollution problem caused by adding toxic oxidants, making it more environmentally friendly. Moreover, this modification strategy is applicable to various hydrophobic materials, has a wide range of applications, and possesses significant application value.

[0004] This invention is achieved through the following technical solution:

[0005] The first aspect of this invention provides a rapid and universally applicable method for modifying polyphenol coatings, the method comprising the following steps:

[0006] S1. Wash the hydrophobic material with ethanol multiple times to achieve pre-wetting of the hydrophobic material;

[0007] S2. The pre-wetted hydrophobic material is immersed in a mixed solution containing polyphenols, silane coupling agents with amino groups and deionized water and reacted for 40 minutes to carry out superhydrophilic modification and obtain a modified film.

[0008] S3. After removing the modified membrane, rinse it thoroughly with deionized water to obtain a polyphenol-coated modified superhydrophilic membrane.

[0009] Furthermore, this invention has good versatility and can be used for the rapid superhydrophilic modification of various polymer hydrophobic materials such as polypropylene (PP), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE).

[0010] Furthermore, the polyphenolic substance is tannic acid (TA); the silane coupling agent with amino groups is 3-aminopropyltriethoxysilane (APTES). The green modification method of this invention involves reacting the polyphenolic substance and the silane coupling agent with amino groups in a pure water system, without adding any toxic oxidants during the modification process, making it environmentally friendly. This solves the problem of secondary pollution caused by the addition of toxic oxidants in previous rapid modification methods.

[0011] Furthermore, the mass ratio of polyphenolic substances to silane coupling agents with amino groups is 1:1 to 8, preferably 1:1, 1:2, 1:4, or 1:8. By using polyphenolic substances and silane coupling agents with amino groups as raw materials, and by controlling their concentration ratio, the reaction rate is controlled, significantly shortening the formation time of the polyphenol coating, improving the modification efficiency of the polyphenol coating on the hydrophobic film, and solving the problem of low modification efficiency of polyphenol coatings in the prior art.

[0012] Furthermore, before adding the ethanol-pre-wetted hydrophobic material to the mixed solution in step S2, excess ethanol should be removed as much as possible. This can be achieved by gently shaking the ethanol-pre-wetted membrane. Because ethanol is a hydrolysis product of 3-aminopropyltriethoxysilane, it inhibits the hydrolysis of 3-aminopropyltriethoxysilane, thus affecting the modification rate. Therefore, to minimize the impact of ethanol on the reaction rate, the pre-wetted hydrophobic membrane should be gently shaken a few times to remove excess ethanol before adding it to the mixed solution.

[0013] The second aspect of the present invention provides a polyphenol-coated modified superhydrophilic membrane prepared by the above modification method, wherein the polyphenol-coated modified superhydrophilic membrane has a layered nanosphere structure.

[0014] The superhydrophilic membrane modified with the polyphenol coating exhibits both superhydrophilicity and underwater superoleophobicity. In particular, the modified PP membrane not only has an extremely high pure water flux (11990 L / m³), but also... -2 h -1 It has high water-in-oil emulsion separation efficiency (>99.8%), and also has excellent mechanical stability, acid and alkali resistance and long-term stability in air.

[0015] The third aspect of this invention provides the application of the polyphenol-coated modified superhydrophilic membrane prepared by the above-described modification method. This invention enables rapid superhydrophilic modification of various hydrophobic membranes to achieve efficient separation of oil-in-water emulsions, which can be used in the field of water purification, specifically for the treatment of oily wastewater.

[0016] Compared with the prior art, the beneficial effects of the present invention include:

[0017] 1. This invention uses polyphenolic substances and silane coupling agents with amino groups as raw materials. By adjusting their concentration ratio and reaction rate, the formation time of polyphenol coating is significantly shortened to only 40 minutes, thereby improving the modification efficiency of hydrophobic film by polyphenol coating.

[0018] 2. The polyphenol coating modification strategy described above has a simple preparation process and does not involve the addition of any toxic oxidants, making it green and environmentally friendly.

[0019] 3. The polyphenol coating modification strategy described above is applicable to various hydrophobic materials such as polypropylene membrane (PP), polyvinylidene fluoride membrane (PVDF), and polytetrafluoroethylene membrane (PTFE), and has a wide range of applications and good application value.

[0020] 4. The separation membrane modified with the polyphenol coating described above exhibits superhydrophilicity and underwater superoleophobicity. More importantly, the modified PP membrane prepared by this method not only has an ultra-high pure water flux (11990 L / m³), but also... -2 h -1 It has high water-in-oil emulsion separation efficiency (>99.8%), and also has excellent mechanical stability, acid and alkali resistance and long-term stability in air. Attached Figure Description

[0021] Figure 1 Schematic diagram of the preparation process for modifying PP, PVDF, and PTFE for polyphenol coating modification.

[0022] Figure 2 These are scanning electron microscope images of the original PP film and the PP film modified with TA-APTES polyphenol coating in Example 1.

[0023] Figure 3 Images of the original PP film and the PP film modified with TA-APTES polyphenol coating in Example 1, along with corresponding images of the water contact angle in the air.

[0024] Figure 4 The images are scanning electron microscope (SEM) images of the TA-APTES polyphenol-coated TA-APTES modified polypropylene (PP), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE) films in Example 1.

[0025] Figure 5 This is a graph showing the flux and separation efficiency of the modified PP membrane used in Example 1 for emulsion separation. In the graph, the horizontal axis PP-(TA-APTES) represents the TA-APTES polyphenol-coated modified PP membrane, and the left vertical axis represents Water Flux, which represents the water flux (L / m³). -2 h -1 The right-hand vertical axis represents the oil rejection rate (%).

[0026] Figure 6 This is a stability test of the modified PP film in Example 1.

[0027] Figure 7 Figures showing the air-water contact angle and underwater oil contact angle of PP films modified with tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) at different mass-volume ratios. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] Example 1: Preparation of modified PP, modified PVDF, and modified PTFE by polyphenol coating modification

[0030] A schematic diagram of the preparation process is shown below. Figure 1 As shown.

[0031] First, the hydrophobic polypropylene membrane (PP), polyvinylidene fluoride membrane (PVDF), and polytetrafluoroethylene membrane (PTFE) are washed with ethanol multiple times, and then pre-wetted with ethanol before use.

[0032] Then, 50 mg of tannic acid (TA) was added to the petri dish, and 25 mL of deionized water was added to dissolve it. After the tannic acid was dissolved, 200 mg of 3-aminopropyltriethoxysilane (APTES) was added to the tannic acid solution.

[0033] The polypropylene (PP), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE) films, pre-wetted with ethanol, were then gently shaken to remove as much ethanol as possible; they were then immersed separately in the mixed solution for 40 minutes. The reaction was carried out at room temperature, and the entire process was conducted on a shaker.

[0034] Remove the modified polypropylene (PP), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE) membranes, wash them with deionized water, and let them air dry.

[0035] Scanning electron microscope images of pristine and modified polypropylene films PP-(TA-APTES) are shown below. Figure 2 As shown, scanning electron microscope images of polypropylene (PP), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE) membranes modified with TA-APTES coating are as follows. Figure 4 As shown, the hydrophobic material modified with polyphenol coating according to this invention has a unique layered nanosphere structure.

[0036] Water contact angles in air for virgin polypropylene (PP) film and modified polypropylene film PP-(TA-APTES) are as follows: Figure 3 As shown, the polyphenol-coated modified polypropylene film PP-(TA-APTES) of the present invention has superhydrophilicity.

[0037] Modified polypropylene film PP-(TA-APTES) exhibits excellent mechanical stability, acid and alkali resistance, and long-term stability in air. For example... Figure 6 As shown, a series of stability tests were conducted on the modified polypropylene film PP-(TA-APTES). Figure 6As shown in (a), the modified polypropylene membrane PP-(TA-APTES) underwent 10 cycles of rinsing. After 10 cycles, the modified polypropylene membrane PP-(TA-APTES) still maintained its superhydrophilic and underwater superoleophobic properties. Figure 6 As shown in (b), the modified polypropylene film PP-(TA-APTES) was ultrasonically treated for 10 minutes. After ultrasonic treatment, the water contact angle and underwater oil contact angle of the modified polypropylene film PP-(TA-APTES) remained at 0° and 160°, respectively, indicating that the modified polypropylene film PP-(TA-APTES) has excellent mechanical stability. Figure 6 As shown in (c), the modified polypropylene membrane PP-(TA-APTES) was immersed in solutions with different pH values ​​(pH = 2, 3, 5, 9, 11) for 12 hours. The underwater oil contact angle of the polypropylene membrane PP-(TA-APTES) was greater than 150° under all pH conditions, indicating that the polypropylene membrane PP-(TA-APTES) has good acid and alkali resistance. Figure 6 As shown in (d), the modified polypropylene film PP-(TA-APTES) was exposed to air for different periods (10 days, 20 days, and 30 days). Even after 30 days of exposure to air, the underwater oil contact angle of PP-3 was approximately 157°, indicating that it still exhibits underwater superoleophobicity. This demonstrates that PP-3 has long-term stability in air.

[0038] Example 2

[0039] The modification steps are the same as in Example 1, except that the reaction rate is controlled by adjusting the concentration ratio of tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES). The mass ratio of polyphenolic substances to silane coupling agents with amino groups is adjusted to 1:1, 1:2, 1:4, and 1:8, respectively. The air-water contact angle and underwater oil contact angle of the PP film modified at each concentration ratio are as follows: Figure 7 As shown, within the same reaction time (40 min), the modified PP film exhibited better hydrophilicity and underwater superoleophobic properties with increasing dosage of 3-aminopropyltriethoxysilane (APTES).

[0040] Example 3: Application of polyphenol-coated modified superhydrophilic membrane in the purification of oily wastewater.

[0041] The TA-APTES polyphenol-coated modified PP membrane prepared in Example 1 was used to test the separation of oil-in-water emulsions. The modified PP membrane was placed in a vacuum filtration system for oil-water separation. The oil-in-water emulsion was prepared by stirring soybean oil, surfactant, and water. Figure 5 As shown, the modified PP membrane has an emulsion separation efficiency of over 99.8%, demonstrating high oil-water separation efficiency, as measured by experiments.

[0042] The above description merely illustrates preferred embodiments of the present invention, and while the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A rapid, green, and universally applicable method for modifying polyphenol coatings, characterized in that, The modification method includes the following steps: S1. Wash the hydrophobic material with ethanol multiple times to achieve pre-wetting of the hydrophobic material; S2. Remove the ethanol from the surface of the hydrophobic material, and then immerse the pre-wetted hydrophobic material in water containing polyphenols, silane coupling agents with amino groups and deionized water for superhydrophilic modification to obtain a modified film. A polyphenolic substance and a silane coupling agent with an amino group are reacted in a pure water system for 40 min; the polyphenolic substance is tannic acid; the silane coupling agent with an amino group is 3-aminopropyltriethoxysilane; the mass ratio of the polyphenolic substance to the silane coupling agent with an amino group is 1:2~8. S3. After removing the modified membrane, rinse it thoroughly with deionized water to obtain a polyphenol-coated modified superhydrophilic membrane; the polyphenol-coated modified superhydrophilic membrane has a layered nanosphere structure. When the hydrophobic material is a polypropylene membrane, a polyphenol-coated modified polypropylene membrane is prepared. After further ultrasonic treatment for 10 min, the water contact angle and underwater oil contact angle of the modified polypropylene membrane PP-(TA-APTES) are maintained at 0° and 160°, respectively. When the modified polypropylene membrane PP-(TA-APTES) is immersed in solutions with different pH values ​​of 2, 3, 5, 9, and 11 for 12 hours, the underwater oil contact angle is greater than 150°.

2. The rapid, green, and universally applicable method for modifying polyphenol coatings according to claim 1, characterized in that: The hydrophobic material is one of polypropylene film, polyvinylidene fluoride film, and polytetrafluoroethylene film.

3. The polyphenol-coated modified superhydrophilic membrane prepared by any of the modification methods described in claims 1 to 2.

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