Pdmapaa@ta-aptes@pvdf composite hydrogel film and preparation method and application thereof

Abstract

The present application relates to a kind of PDMAPAA@TA-APTES@PVDF composite hydrogel film and its preparation method and application.The present application uses PVDF as base film, material is cheap, mechanical performance is good, environment-friendly, and good recycling performance.Iron ion (Fe 3+ ) And tannic acid (TA) are used to construct double autocatalysis system, and PDMAPAA@TA-APTES@PVDF composite hydrogel film is prepared rapidly, efficiently and massively under mild conditions.The prepared PDMAPAA@TA-APTES@PVDF composite hydrogel film has high flux, superhydrophilicity, underwater superoleophobicity and long-time stable antifouling property.The preparation method of the present application is simple, easy to operate, low in energy consumption, easy to handle and free of secondary pollution, in line with the concept of green chemistry, and has good application prospect in oil-water separation field.The prepared antifouling oil-water separation membrane has superhydrophilicity and excellent antifouling property, can be operated stably for a long time, and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The application relates to a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane and a preparation method and application thereof, and belongs to the technical field of environment functional material preparation. BACKGROUND

[0002] Oil-containing wastewater produced in industry and daily life has a serious impact on the ecosystem and human health, and efficient treatment of oil-containing wastewater is a global concern. Membrane separation technology is distinguished from other traditional methods due to its energy saving, mild operating conditions, cost-effectiveness and other advantages. However, membrane fouling inevitably leads to a significant decrease in the flux of traditional membranes. This fatal weakness not only leads to low separation efficiency and high energy consumption, but also restricts the development of the technology in the treatment of oil-containing wastewater. Therefore, it is very important to improve the anti-fouling performance of separation membranes.

[0003] Surface hydrophilic modification is an effective way to enhance the anti-fouling performance of membranes. It can form a hydration layer and micro-nano structure on the membrane surface, prevent oil and other pollutants from directly contacting and adhering to the membrane surface, form an effective "pollution resistance" barrier, and reduce the pollution of oil to the separation membrane. Therefore, the stronger the hydration of the membrane material, the stronger the anti-oil pollution performance. Hydrogel is a kind of polymer material with three-dimensional network structure formed by cross-linking of hydrophilic compounds through chemical and physical action, which has super high hydrophilic performance and can form a solid hydration layer on the membrane surface. Moreover, the low Young's modulus of hydrogel endows the membrane surface with a larger excluded volume and enhances the steric hindrance effect. Therefore, the hydrogel layer of the hydrogel membrane will integrate and strengthen the pollution resistance mechanism on the membrane surface, improve the hydrophilicity and oleophobicity of the membrane surface, and thus improve the permeability and anti-pollution performance of the membrane surface. However, the process of preparing a composite hydrogel membrane by traditional methods is relatively complex, and the reaction conditions are relatively harsh. The polymerization process usually includes monomers, chemical cross-linking agents and toxic adjuvants, and the gelation process depends on external stimuli, which requires strong ultraviolet irradiation or high heating temperature. Therefore, it is still a major challenge to prepare a composite hydrogel membrane at room temperature or low temperature without external stimuli.

[0004] In recent years, by learning from the catalytic performance of mussel-inspired / natural polyphenol, a self-catalytic system of polyphenol-metal ion is constructed by combining transition metal, which is used for constructing super-strong hydrogel based on mussel-inspired / natural polyphenol and has become an important research hotspot. A new dual self-catalytic system composed of multiple variable valence metal ions and compounds containing o-diphenol groups can effectively catalyze the polymerization of hydrogel without external stimuli, and efficiently and rapidly prepare hydrogel. However, there is no report on the application of this method to prepare hydrogel membranes. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to overcome the technical defects of the prior art, and provide a method for efficiently, quickly and large-scale preparation of PDMAPAA@TA-APTES@PVDF composite hydrogel film. Specifically, the present application first forms a TA-APTES micro-nano sphere coating on the PVDF base film by Michael addition reaction of TA and APTES to obtain TA-APTES@PVDF film, and then uses a double autocatalytic system composed of oxidizing high-valence metal iron ions (Fe 3+ ) and reducing tannic acid (TA) containing catechol functional groups to initiate the polymerization of dimethylaminopropyl acrylamide (DMAPAA) on the surface of TA-APTES@PVDF film, and prepare a high-flux anti-pollution PDMAPAA@TA-APTES@PVDF composite hydrogel film.

[0006] The present application modifies the surface of commercial PVDF film, which is simple to operate, short in modification reaction time, high in efficiency, suitable for roll film production line and suitable for industrial production. The prepared anti-pollution oil-water separation membrane has a super-hydrophilic surface and excellent anti-pollution properties, and can be stably operated for a long time under high-concentration oil-water separation conditions.

[0007] The present application modifies the TA-APTES micro-nano sphere coating on the PVDF base film, and then uses a double autocatalytic system composed of oxidizing high-valence metal iron ions (Fe 3+ ) and tannic acid (TA) to initiate the polymerization of dimethylaminopropyl acrylamide (DMAPAA) on the surface of the film, and quickly and efficiently prepare a high-flux anti-pollution PDMAPAA@TA-APTES@PVDF composite hydrogel film under mild conditions, thereby improving the flux and anti-pollution performance of the film, solving the problems of pollution, low flux and poor interfacial bonding stability of traditional separation membranes, and enabling the prepared PDMAPAA@TA-APTES@PVDF composite hydrogel film to separate various oil-water emulsions, greatly improving the separation efficiency and anti-pollution performance, and being able to be stably operated for a long time under high-concentration oil-water separation conditions.

[0008] The technical solution adopted by the present application is as follows: the present application is completed by three steps of reaction:

[0009] (1) Preparation of PVDF base film: completely immerse the commercially available hydrophobic PVDF film (polyvinylidene fluoride film) in anhydrous ethanol to obtain a PVDF base film.

[0010] (2) Synthesis of TA-APTES@PVDF film: form a TA-APTES micro-nano sphere coating on the PVDF base film by Michael addition reaction of TA and APTES to prepare a TA-APTES@PVDF film.

[0011] (3) Synthesis of PDMAPAA@TA-APTES@PVDF composite hydrogel membrane: The prepared TA-APTES@PVDF membrane was placed in a beaker containing a mixed solution of Fe 3+ , MBAA, (NH4)2S2O8 and DMAPAA, and a double autocatalytic system was constructed by Fe 3+ and TA to catalyze the polymerization of DMAPAA to obtain a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane.

[0012] In step (1), the PVDF membrane was immersed in anhydrous ethanol and then subjected to the next reaction.

[0013] In step (2), the solvent used was 25-35 ml of deionized water; the TA used was 40-60 mg, and the APTES used was 600-800 μl; and the reaction condition was 25°C water bath oscillation for 30-50 min.

[0014] In step (3), the solvent used was 4-8 ml of deionized water; the FeCl3·6H2O used was 50-70 mg, the (NH4)2S2O8 used was 8-12 mg, and the MBAA used was 10-14 mg, and 30-70 μl of DMAPAA was added after complete dissolution; and the reaction condition was 25°C water bath oscillation for 1.5-2.5 h.

[0015] The above PDMAPAA@TA-APTES@PVDF composite hydrogel membrane was applied to oil-water separation experiments:

[0016] In the oil-water emulsion used in the experiment, the volume ratio of water to oil was 99:1, and 10 mg of ionic surfactant was added, and the emulsion was stirred for 12 h to form a stable emulsion. The oil-water emulsion was separated using a suction filtration device at a pressure of 0.2 bar and a stirring speed of 300 r / min. The transmittance between wavelengths of 400 nm and 800 nm was measured using a UV spectrophotometer (UH5300 type), and the oil concentration in the emulsion and filtrate was calculated. The separation efficiency was calculated by the following formula:

[0017]

[0018] In the formula, S is the separation efficiency of the oil-in-water emulsion, T feed is the average transmittance of the prepared emulsion. T0 is the average transmittance of the corresponding pure water; and T1 is the average transmittance of the filtrate after separation.

[0019] The permeation flux of the membrane was calculated by the following formula:

[0020]

[0021] In the formula, J is the permeation flux of the membrane (L·m-2 ·h -1 ·bar -1 ), A is the effective area (m 2 ) of the separation membrane, Δt is the time (h) of the solution passing through the membrane, and ΔP is the operating pressure (bar).

[0022] In Figure 6 , the separation material involved is petroleum ether, hexane, cyclohexane, dichloroethane, toluene, and the emulsion to be separated is an emulsion with a volume ratio of water to oil (the above-mentioned substances) of 99:1.

[0023] The present application has the following advantages:

[0024] (1) The present application uses PVDF as the base film, which is low in material cost, good in mechanical properties, friendly to the environment, and good in recycling performance.

[0025] (2) A double autocatalysis system is constructed by using iron ions (Fe 3+ ) and tannic acid (TA) to rapidly, efficiently and massively prepare PDMAPAA@TA-APTES@PVDF composite hydrogel membrane under mild conditions.

[0026] (3) The prepared PDMAPAA@TA-APTES@PVDF composite hydrogel membrane has high flux, superhydrophilicity, underwater superoleophobicity and long-term stable antifouling properties.

[0027] (4) The preparation method of the present application is simple, easy to operate, low in energy consumption, easy to handle and free of secondary pollution, which meets the concept of green chemistry and has good application prospect in the field of oil-water separation; the prepared antifouling oil-water separation membrane has superhydrophilicity and excellent antifouling properties, can be stably operated for a long time, and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a scanning electron microscope image of a hydrophobic PVDF base film.

[0029] Figure 2 is a scanning electron microscope image of the prepared TA-APTES@PVDF membrane.

[0030] Figure 3 is a scanning electron microscope image of the prepared PDMAPAA@TA-APTES@PVDF composite hydrogel membrane

[0031] Figure 4 is a water contact angle photo of the prepared PDMAPAA@TA-APTES@PVDF composite hydrogel membrane.

[0032] Figure 5 The underwater dichloroethane contact angle photo of the prepared PDMAPAA@TA-APTES@PVDF composite hydrogel film.

[0033] Figure 6 The permeation flux and separation efficiency diagram of different types of oil-water emulsion of the prepared PDMAPAA@TA-APTES@PVDF composite hydrogel film (a) and after acid (b), base (c), salt (d) environment treatment.

[0034] Figure 7 The cycle separation experiment diagram of the prepared PDMAPAA@TA-APTES@PVDF composite hydrogel film.

[0035] Figure 8 The mass production of the PDMAPAA@TA-APTES@PVDF composite hydrogel film and its permeation flux and separation efficiency diagram for n-hexane emulsion.

[0036] Specific example mode

[0037] The following detailed description of the embodiments of the present application is given on the premise of the technical solutions of the present application, and detailed operation procedures and specific reaction conditions are given, but the protection scope of the present application is not limited to the following examples.

[0038] Example 1

[0039] Step 1: Preparation of PVDF base film: completely immerse the commercially available hydrophobic PVDF film in anhydrous ethanol to obtain a PVDF base film.

[0040] Figure 1 It can be seen that the surface of the hydrophobic PVDF base film is relatively smooth, and the pore size is sparse.

[0041] Step 2: Synthesis of TA-APTES@PVDF film: dissolve 50 mg of TA (tannic acid) in a beaker containing 25 ml of deionized water, add 600 μl of APTES (3-aminopropyl triethoxysilane), and when APTES begins to hydrolyze, put the PVDF base film immersed in anhydrous ethanol into it, seal the beaker with a sealing film, and shake in a water bath at 25°C for 40 min. TA and APTES undergo Michael addition reaction to form a TA-APTES micro-nano ball coating on the PVDF base film, and a TA-APTES@PVDF film is prepared.

[0042] Figure 2 It can be seen that the surface of the TA-APTES@PVDF film has grown many small balls compared with the PVDF base film, and becomes rough, and the pore size is reduced, indicating that TA-APTES is successfully crosslinked on the surface of the PVDF film.

[0043] Step 3: Synthesis of PDMAPAA@TA-APTES@PVDF composite hydrogel membrane: 58 mg FeCl3·6H2O, 10 mg (NH4)2S2O8, 12 mg MBAA (N,N-methylenebisacrylamide) were dissolved in a beaker containing 6 ml deionized water, 50 μl DMAPAA (dimethylaminopropyl acrylamide) was added, the prepared TA-APTES@PVDF membrane was placed therein, the beaker was sealed with sealing film, and water bath oscillation was carried out at 25°C for 2 h. Fe 3+ and TA to construct a dual autocatalytic system to catalyze the polymerization of DMAPAA to obtain a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane.

[0044] Figure 3 It can be seen that the PDMAPAA@TA-APTES@PVDF composite hydrogel membrane grows a gel structure on the surface compared with the TA-APTES@PVDF membrane, and the small balls are wrapped therein, and the pore size is smaller, indicating that DMAPAA is successfully polymerized on the surface of the TA-APTES@PVDF membrane.

[0045] Figure 4 It can be seen that the PDMAPAA@TA-APTES@PVDF composite hydrogel membrane presents superhydrophilic performance.

[0046] Figure 5 It can be seen that the PDMAPAA@TA-APTES@PVDF composite hydrogel membrane has underwater superoleophobicity.

[0047] Figure 6 It can be seen that the PDMAPAA@TA-APTES@PVDF composite hydrogel membrane has unchanged permeation flux and separation efficiency for different types of oil-water emulsion after treatment in acid, alkali and salt environments.

[0048] Figure 7 It can be seen that the PDMAPAA@TA-APTES@PVDF composite hydrogel membrane still has high permeation flux and separation efficiency after 15 cycles of separation of n-hexane emulsion.

[0049] Figure 8 It can be seen that the large-scale prepared PDMAPAA@TA-APTES@PVDF composite hydrogel membrane has high permeation flux and separation efficiency.

[0050] Example 2:

[0051] Step 1: Preparation of PVDF-based membrane: commercially available hydrophobic PVDF membrane was completely immersed with anhydrous ethanol to obtain a PVDF-based membrane.

[0052] Step 2: Synthesis of TA-APTES@PVDF film: 50 mg of TA was dissolved in a beaker containing 25 ml of deionized water, 600 μl of APTES was added, and the PVDF-based film immersed in anhydrous ethanol was placed in it when APTES began to hydrolyze. The beaker was sealed with a sealing film, and shaken in a water bath at 25°C for 40 min. TA and APTES underwent Michael addition reaction to form a TA-APTES micro-nanosphere coating on the PVDF-based film, and a TA-APTES@PVDF film was prepared.

[0053] Step 3: Synthesis of PDMAPAA@TA-APTES@PVDF composite hydrogel film: 58 mg of FeCl3·6H2O, 10 mg of (NH4)2S2O8, and 12 mg of MBAA were dissolved in a beaker containing 6 ml of deionized water, 50 μl of DMAPAA was added, and the prepared TA-APTES@PVDF film was placed in it. The beaker was sealed with a sealing film, and shaken in a water bath at 25°C for 2 h. Fe 3+ and TA to construct a dual autocatalytic system to catalyze the polymerization of DMAPAA to obtain a PDMAPAA@TA-APTES@PVDF composite hydrogel film.

[0054] Example 3:

[0055] Step 1: Preparation of PVDF-based film: commercially available hydrophobic PVDF film was completely immersed in anhydrous ethanol to obtain a PVDF-based film.

[0056] Step 2: Synthesis of TA-APTES@PVDF film: 50 mg of TA was dissolved in a beaker containing 25 ml of deionized water, 700 μl of APTES was added, and the PVDF-based film immersed in anhydrous ethanol was placed in it when APTES began to hydrolyze. The beaker was sealed with a sealing film, and shaken in a water bath at 25°C for 50 min. TA and APTES underwent Michael addition reaction to form a TA-APTES micro-nanosphere coating on the PVDF-based film, and a TA-APTES@PVDF film was prepared.

[0057] Step 3: Synthesis of PDMAPAA@TA-APTES@PVDF composite hydrogel film: 58 mg of FeCl3·6H2O, 10 mg of (NH4)2S2O8, and 12 mg of MBAA were dissolved in a beaker containing 6 ml of deionized water, 50 μl of DMAPAA was added, and the prepared TA-APTES@PVDF film was placed in it. The beaker was sealed with a sealing film, and shaken in a water bath at 25°C for 2 h. Fe 3+ and TA to construct a dual autocatalytic system to catalyze the polymerization of DMAPAA to obtain a PDMAPAA@TA-APTES@PVDF composite hydrogel film.

[0058] Example 4:

[0059] Step 1: Preparation of PVDF base film: Commercially available hydrophobic PVDF film was completely immersed with anhydrous ethanol to obtain PVDF base film.

[0060] Step 2: Synthesis of TA-APTES@PVDF film: 50 mg of TA was dissolved in a beaker containing 25 ml of deionized water, 700 μl of APTES was added, and the PVDF base film immersed with anhydrous ethanol was placed therein when APTES began to hydrolyze. The beaker was sealed with a sealing film, and shaken in a water bath at 25°C for 40 min. TA and APTES underwent Michael addition reaction to form a TA-APTES micro-nanosphere coating layer on the PVDF base film to obtain TA-APTES@PVDF film.

[0061] Step 3: Synthesis of PDMAPAA@TA-APTES@PVDF composite hydrogel film: 58 mg of FeCl3·6H2O, 10 mg of (NH4)2S2O8, and 12 mg of MBAA were dissolved in a beaker containing 6 ml of deionized water, 70 μl of DMAPAA was added, and the prepared TA-APTES@PVDF film was placed therein. The beaker was sealed with a sealing film, and shaken in a water bath at 25°C for 2 h. Fe 3+ and TA to construct a dual autocatalytic system to catalyze the polymerization of DMAPAA to obtain PDMAPAA@TA-APTES@PVDF composite hydrogel film.

[0062] Example 5:

[0063] Step 1: Preparation of PVDF base film: Commercially available hydrophobic PVDF film was completely immersed with anhydrous ethanol to obtain PVDF base film.

[0064] Step 2: Synthesis of TA-APTES@PVDF film: 50 mg of TA was dissolved in a beaker containing 25 ml of deionized water, 700 μl of APTES was added, and the PVDF base film immersed with anhydrous ethanol was placed therein when APTES began to hydrolyze. The beaker was sealed with a sealing film, and shaken in a water bath at 25°C for 40 min. TA and APTES underwent Michael addition reaction to form a TA-APTES micro-nanosphere coating layer on the PVDF base film to obtain TA-APTES@PVDF film.

[0065] Step 3, synthesis of PDMAPAA@TA-APTES@PVDF composite hydrogel film: 40 mg FeCl3·6H2O, 10 mg (NH4)2S2O8, 12 mg MBAA were dissolved in a beaker containing 6 ml deionized water, 50 μl DMAPAA was added, the prepared TA-APTES@PVDF film was placed therein, the beaker was sealed with a sealing film, and the water bath was oscillated at 25°C for 2 h. Fe 3+ and TA to construct a dual autocatalysis system to catalyze the polymerization of DMAPAA to obtain a PDMAPAA@TA-APTES@PVDF composite hydrogel film.

[0066] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent transformation or modification according to the spirit and essence of the present application should be covered in the protection scope of the present application.

Claims

1. A method for preparing a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane, characterized in that, The steps are as follows: Step 1: Preparation of PVDF base film: The hydrophobic PVDF film is completely impregnated with anhydrous ethanol to obtain the PVDF base film; Step 2: Preparation of TA-APTES@PVDF membrane: TA and APTES undergo a Michael addition reaction to form a TA-APTES micro / nanosphere coating on the PVDF substrate, thus preparing the TA-APTES@PVDF membrane; Step 3: Preparation of PDMAPAA@TA-APTES@PVDF composite hydrogel membrane: using Fe 3+ A dual autocatalytic system was constructed with tannic acid (TA) and reacted at room temperature to initiate the polymerization of dimethylaminopropylacrylamide (DMAPAA) on the surface of the prepared TA-APTES@PVDF membrane, thereby obtaining a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane.

2. The method for preparing a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane as described in claim 1, characterized in that, In step 1, the commercially available hydrophobic PVDF membrane is completely wetted with anhydrous ethanol and then taken out for the next reaction.

3. The method for preparing a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane as described in claim 1, characterized in that, In step 2, the reaction conditions for TA and APTES are water bath shaking at 25°C; the reaction time is 30-50 min.

4. The method for preparing a PDMAPAA@TA-APTES@PVDF composite hydrogel membrane as described in claim 1, characterized in that, In step 3, the reaction conditions are water bath shaking at 25°C; the reaction time is 2 hours, Fe 3+ It is derived from FeCl3·6H2O, wherein the FeCl3·6H2O content is 50–70 mg.

5. A PDMAPAA@TA-APTES@PVDF composite hydrogel membrane prepared by any one of the preparation methods of PDMAPAA@TA-APTES@PVDF composite hydrogel membranes as described in any one of claims 1-4, characterized in that, It includes a PVDF membrane having a TA-APTES micro / nanosphere coating and PDMAPAA.

6. The use of the PDMAPAA@TA-APTES@PVDF composite hydrogel membrane according to claim 5 for the separation of oil-water emulsions.

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