Preparation method for polyvinylidene fluoride modified composite film

A technology of polyvinylidene fluoride and composite membrane, which is applied in chemical instruments and methods, membrane technology, semipermeable membrane separation, etc., can solve the problems of inconvenient catalyst recovery and poor catalytic degradation effect, and achieve good catalytic degradation effect and solve Effects of Recycling Questions

Inactive Publication Date: 2019-01-29
TIANJIN JINLIN WATER TREATMENT SCI & TECH CO LTD
10 Cites 1 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0004] The invention proposes a method for preparing a polyvinylidene fluoride modified composite membrane to solve te...
View more

Method used

Zinc oxide (ZnO) is used in photocatalytic degradation pollutant process as n-type semiconductor oxide, has following problem: (1) need the aftertreatment that catalyst removes; (2) easily form agglomerate in solution, Reduce the effective surface area; (3) It is difficult to realize the complete recovery of the catalyst; (4) The photogenerated electrons and holes recombine in a short time. As an excellent carri...
View more

Abstract

The invention provides a preparation method for a polyvinylidene fluoride modified composite film. The preparation method comprises the following steps: a) preparation of graphene oxide through an improved Hummer's chemical method; b) preparation of aminated graphene oxide; c) preparation of an amino-functionalized graphene oxide/zinc oxide composite photocatalyst; and d) preparation of a polyvinylidene fluoride modified composite film. The polyvinylidene fluoride modified composite film prepared by using the preparation method provided by the invention is mainly applied to treatment of organic pollutants in sewage, can effectively solve the problem of catalyst recovery, can degrade organic matters contaminating PVDF, realizes the self-cleaning function of a composite film, and has excellent catalytic degradation effect.

Application Domain

Semi-permeable membranesCatalyst carriers +4

Technology Topic

Polyvinylidene fluorideChemistry +13

Image

  • Preparation method for polyvinylidene fluoride modified composite film
  • Preparation method for polyvinylidene fluoride modified composite film
  • Preparation method for polyvinylidene fluoride modified composite film

Examples

  • Experimental program(4)
  • Comparison scheme(1)
  • Effect test(1)

Example Embodiment

[0024] A preparation method of a polyvinylidene fluoride modified composite membrane, comprising the steps of:
[0025] a) Graphene oxide (GO) was prepared by an improved Hummer's chemical method;
[0026] b) Preparation of aminated graphene oxide (NGO): performing amination modification on the graphene oxide obtained in step a) to obtain aminated graphene oxide;
[0027] c) Preparation of amino-functionalized graphene oxide/zinc oxide (NGO-ZnO) composite photocatalyst; dissolving the aminated graphene oxide obtained in step b) in absolute ethanol, ultrasonically dispersing, adding zinc acetate dihydrate, and heating to dihydrate After the zinc acetate is completely dissolved, add the ethanol solution of potassium hydroxide, then place it in the reaction kettle for reaction, wash and dry to obtain the NGO-ZnO composite photocatalyst;
[0028] d) Preparation of polyvinylidene fluoride modified composite membrane (PVDF/NGO-ZnO), as follows:
[0029] d1) After ultrasonically dispersing the NGO-ZnO composite photocatalyst obtained in step c) in a polyethylene glycol (PEG) dimethylformamide solution (DMF), add PVDF, and under constant temperature conditions, stir until the PVDF is completely dissolved and then stand still Degassing until no bubbles are produced to obtain the casting solution;
[0030] d2) Add the casting liquid onto a dry glass plate dropwise, scrape the film, and quickly immerse the obtained film in a pure water coagulation bath. After the film is formed, wash it with pure water to obtain a PVDF/NGO-ZnO composite film.
[0031] When zinc oxide (ZnO) is used as an n-type semiconductor oxide in the process of photocatalytic degradation of pollutants, there are the following problems: (1) post-treatment for catalyst removal is required; (2) agglomerates are easily formed in the solution, reducing the effective surface area ; (3) It is difficult to realize the complete recovery of the catalyst; (4) The photogenerated electrons and holes recombine in a short time. As an excellent carrier and electron transport material, nitrogen-doped graphene (NGO) has a large surface area and excellent electrical conductivity and mechanical properties. NGO modified ZnO can effectively inhibit the recombination of photogenerated electrons. Compared with zinc oxide itself As a photocatalyst, the photocatalytic performance is improved, but there is still the problem that the photocatalyst is not easy to recycle.
[0032] As a membrane material, polyvinylidene fluoride (PVDF) is widely used in the treatment of organic pollutants due to its good chemical stability, high mechanical strength, and excellent anti-aging performance. PVDF reprocessing process is required.
[0033] Therefore, the embodiment of the present invention combines PVDF as a carrier with an NGO-ZnO composite photocatalyst, and proposes a method for preparing a PVDF/NGO-ZnO composite film. The NGO-ZnO composite photocatalyst is loaded on a PVDF carrier to form a composite film with The composite membrane with high catalytic degradation performance can not only effectively solve the problem of catalyst recovery, but also degrade the organic matter that pollutes PVDF, realize the self-cleaning function of the composite membrane, and at the same time have a good catalytic degradation effect.
[0034] Further, in step c), the concentration of aminated graphene oxide in absolute ethanol is 0.1-15 mg/ml; the concentration of zinc acetate dihydrate is 0.1-15 mg/ml; the concentration of aminated graphene oxide and zinc acetate dihydrate The mass ratio is 1:1-1:100.
[0035] Further, in step c), the reaction temperature in the reactor is 80-150°C, and the reaction time is 3-12h.
[0036] Further, in step c), the ethanol solution of potassium hydroxide is prepared by ultrasonically dissolving 0.5-3 g of potassium hydroxide in 1-10 ml of absolute ethanol.
[0037] In one embodiment of the present invention, in step d1), the amount of amino-functionalized graphene oxide/zinc oxide composite photocatalyst accounts for 0.1-1wt% of the dimethylformamide solution; specifically, it can be 0.1wt%, 0.2wt%, 0.4 wt%, 0.5wt%, 0.8wt%, 1wt%. Within this range, with the increase in the amount of NGO-ZnO composite photocatalyst, the catalytic degradation ability of the composite film gradually increases, but if the amount of NGO-ZnO composite photocatalyst is too much, it will cause photocatalyst aggregation, reduce the light utilization rate, and affect the catalytic performance. Degradation performance, while the catalyst is not easy to recycle. Preferably, the amount of the NGO-ZnO composite photocatalyst accounts for 0.5 wt% of the dimethylformamide solution. The catalytic effect of the composite membrane at this ratio is the best.
[0038] Further, in step d1), the amount of PVDF accounted for dimethylformamide solution can be 2-20wt%; preferably, the amount of PVDF accounted for dimethylformamide solution 16-20wt%, specifically can be 16wt%, 18wt% %, 20wt%. Excessive use of PVDF will reduce the self-cleaning performance of the composite membrane.
[0039] Further, in step d1), the mass ratio of NGO-ZnO composite photocatalyst to PVDF is 1:1-40. Preferably, the mass ratio of NGO-ZnO composite photocatalyst to PVDF is 1:20-32. The appropriate ratio of NGO-ZnO composite photocatalyst to PVDF is beneficial to the uniform loading of the composite photocatalyst on PVDF, thereby improving the catalytic performance.
[0040] Further, in step d1), the constant temperature is 20-80°C; preferably, the constant temperature is 55-65°C; more preferably, the constant temperature is 60°C. This temperature range is conducive to better dissolution of PVDF, which is beneficial to the loading of NGO-ZnO photocatalyst.
[0041] Further, in step d1), the concentration of polyethylene glycol can be 2-8wt%; specifically, it can be 2wt%, 4wt%, 6wt%, 8wt%, etc.
[0042] Further, in step d1), the standing time for defoaming can be 1-24h. Specifically, it can be 10h, 12h, 15h, etc., for example, the standing defoaming time is 12h. Stand for defoaming until no bubbles are produced in the casting solution.
[0043] Further, in step d2), the temperature of the coagulation bath may be 10-60°C. Specifically, it may be 20°C, 25°C, or 30°C. For example, the temperature of the coagulation bath may be 25°C. The temperature of the coagulation bath has an important influence on the forming effect of the composite membrane. Too low or too high temperature is not conducive to the forming of the composite membrane.
[0044] Further, in step d2), the film scraping rod used in the scraping film may have a thickness of 100-300 μm; specifically, it may be 100 μm, 200 μm, 300 μm, etc.
[0045] In a preferred embodiment of the present invention, the amount of the amino-functionalized graphene oxide/zinc oxide composite photocatalyst accounts for 0.5 wt% of the dimethylformamide solution, and the amount of PVDF accounts for 16-20 wt% of the dimethylformamide solution.
[0046] In one embodiment of the present invention, step a) utilizes improved Hummer's chemical method to prepare graphene oxide (GO), specifically can be:
[0047] Add 5-20g of pretreated graphite powder and 1-10g of sodium nitrate into a reactor containing 100-500ml of concentrated sulfuric acid, stir in an ice-water bath for 0.5-5h, then slowly add 10-50g of potassium permanganate and continue stirring 1-5h; then raise the temperature of the reaction system to 10-50°C, continue the reaction for 1-5h, slowly add 100-500ml of deionized water, raise the temperature of the reaction system to 50-150°C and stir for 5-30min; then add to the system Slowly add 200-1000ml of deionized water, stir for 1-10min, then add 10-50ml of 30wt% hydrogen peroxide to terminate the reaction, the color of the solution changes from black to bright yellow, continue to stir for 10-30min, then pickle the product, Washed with water to pH ≈ 7, suction filtered and freeze-dried to obtain graphene oxide (GO), ready for use.
[0048] In an embodiment of the present invention, step b) prepares aminated graphene oxide (NGO), which may specifically be:
[0049] Weigh 30-50 mg of GO obtained in step a) and disperse it in a beaker containing N,N methyl-formamide (DMF), cool the GO solution to 0 °C, and then add 3-8 mmol 1-( 3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 3-8 mmol N-hydroxysuccinimide (NHS). After the mixture was activated at 0° C. for 0.5-5 h, 6-15 mmol of diethylenetriamine was added to the solution and stirred overnight at room temperature. The product was centrifuged, washed three times with acetone and water respectively, and freeze-dried to obtain aminated graphene oxide (NGO), which was ready for use.
[0050] In one embodiment of the present invention, step c) prepares amino-functionalized graphene oxide/zinc oxide composite photocatalyst (NGO-ZnO), which may specifically be:
[0051] Weigh 0.5-3g of potassium hydroxide (KOH) and ultrasonically dissolve it in 1-10ml of absolute ethanol for use. Dissolve 1-100mg of the aminated graphene oxide (NGO) obtained in step b) in 10-100mL of absolute ethanol, disperse it ultrasonically, and add 10-500mg of zinc acetate dihydrate to the solution, and raise the temperature in an oil bath to 50 -100°C, after the zinc acetate dihydrate is completely dissolved, quickly add 1-3ml of KOH ethanol solution and let it react for 3-10min, then transfer the above liquid to a tetrafluoroethylene-lined reactor and raise the temperature to 80-150°C and Keep for 3-12h. Finally, wash with deionized water three times, wash with absolute ethanol once, and dry at 25-80°C. This is also reported in related literature (Dongdong Zhang, Yiping Zhao, et al. "Fabrication and characterization of amino-grafted graphene oxide modified ZnO with high photocatalytic activity." Applied Surface Science 458(2018):638–647.).

Example Embodiment

[0053] Example 1
[0054] a) Preparation of graphene oxide by modified Hummer's chemistry
[0055] 5g of pretreated graphite and 2.5g of sodium nitrate were added to a reactor containing 120ml of sulfuric acid, and after stirring for 1h under an ice-water bath, 15g of potassium permanganate was slowly added and stirring was continued for 2h; then the reaction system was heated to 35°C, After continuing to react for 2 hours, slowly add 120ml of deionized water, raise the temperature of the reaction system to 90°C and stir for 15 minutes; then slowly add 250ml of deionized water to the system, stir for 2 minutes and then add 12ml of 30wt% hydrogen peroxide to terminate the reaction, the color of the solution is From black to bright yellow, continue to stir for 15 minutes, pickle the product, wash with water to pH ≈ 7, filter and freeze-dry to obtain graphene oxide (GO), ready to use;
[0056] b) Preparation of aminated graphene oxide (NGO)
[0057] Disperse 30 mg of GO obtained in step a) in 50 ml of DMF, after 1 hour of ultrasonic treatment, cool the GO solution to 0 °C, and then add 5 mmol of 1-(3-dimethylaminopropyl)-3-ethyl Carbodiimide hydrochloride (EDC) and 5 mmol N-hydroxysuccinimide (NHS), the mixture was stirred at 0° C. for 2 h, then 12 mmol diethylenetriamine was added and stirred overnight at room temperature. The product was centrifuged, washed three times with acetone and water respectively, and freeze-dried to obtain aminated graphene oxide (NGO) for use;
[0058] c) Preparation of amino functionalized graphene oxide/zinc oxide composite photocatalyst (NGO-ZnO)
[0059] Weigh 70 mg of the NGO obtained in step b) and dissolve it in 35 mL of absolute ethanol, disperse it ultrasonically, and add 384 mg of zinc acetate dihydrate to the solution, heat up to 75°C in an oil bath, and after the zinc acetate dihydrate is completely dissolved, quickly After adding 1.5ml of KOH ethanol solution and allowing it to react for 5 minutes, transfer the above liquid to a tetrafluoroethylene-lined reaction kettle and raise the temperature to 150°C and keep it for 5 hours. Finally, wash it with deionized water three times and absolute ethanol once. Drying at ℃ to obtain amino-functionalized graphene oxide/zinc oxide (NGO-ZnO) composite photocatalyst, ready for use;
[0060] d) Preparation of polyvinylidene fluoride modified composite membrane (PVDF/NGO-ZnO)
[0061] d1) 0.3 wt% of the photocatalyst prepared in step c) was ultrasonically dispersed in a DMF solution with a PEG concentration of 8 wt%, and 10 wt% of PVDF powder was added to the solution. The mixed solution was stirred at a constant temperature of 55° C. until the PVDF was completely dissolved, and left at this temperature for defoaming for 12 hours to obtain a casting solution.
[0062] d2) Add the casting solution dropwise on a dry glass plate, and scrape a flat film with a film scraping rod with a thickness of 300 μm. Rapidly immerse the nascent film in a pure water coagulation bath at 25°C, wash it with a large amount of pure water after the film is formed, and store it in pure water to obtain a polyvinylidene fluoride modified composite film.

Example Embodiment

[0063] Example 2
[0064] a)-c) with embodiment 1;
[0065] d) Preparation of polyvinylidene fluoride modified composite membrane
[0066] d1) 0.5 wt% of the NGO-ZnO photocatalyst prepared in step c) was ultrasonically dispersed in a DMF solution with a PEG concentration of 8 wt%, and 16 wt% of PVDF powder was added to the solution. The mixed solution was stirred at 60° C. until the PVDF was completely dissolved, and left at this temperature for defoaming for 12 hours to obtain a casting solution.
[0067] d2) Add the casting solution dropwise on a dry glass plate, and scrape a flat film with a film scraping rod with a thickness of 300 μm. Rapidly immerse the nascent film in a pure water coagulation bath at 25°C, wash it with a large amount of pure water after the film is formed, and store it in pure water to obtain a polyvinylidene fluoride modified composite film.

PUM

PropertyMeasurementUnit
Concentration10.0mg/l

Description & Claims & Application Information

We can also present the details of the Description, Claims and Application information to help users get a comprehensive understanding of the technical details of the patent, such as background art, summary of invention, brief description of drawings, description of embodiments, and other original content. On the other hand, users can also determine the specific scope of protection of the technology through the list of claims; as well as understand the changes in the life cycle of the technology with the presentation of the patent timeline. Login to view more.

Similar technology patents

Hydroxyl functionalized heteropolyacid catalyst as well as preparation method and application thereof

InactiveCN107866281ASolving Recycling Problemslow cost
Owner:NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI +1

Classification and recommendation of technical efficacy words

Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products