A method for preparing a hydrophilic oil-water separation anti-fouling membrane and the anti-fouling membrane and applications thereof

Abstract

The application discloses a preparation method of a hydrophilic oil-water separation anti-pollution membrane and the anti-pollution membrane and application thereof, and prepares MNRs material; the MNRs material is dispersed in dimethylacetamide, is uniformly stirred, polyvinylpyrrolidone is added, and stirring is continued, and a first mixture is obtained through ultrasonic treatment; the first mixture is mixed with polyvinylidene fluoride to obtain a second mixture, and the second mixture is stirred; the treated second mixture is dip-coated on a carrier, the dip-coated carrier is treated in deionized water to obtain an ultrafiltration membrane; the ultrafiltration membrane is soaked in a tea polyphenol solution with a Tris-HCl buffer solution, and is shaken to obtain the hydrophilic oil-water separation anti-pollution membrane. The hydrophilic oil-water separation anti-pollution membrane has excellent separation efficiency and flux recovery rate for four different oil-water mixtures of kerosene, gasoline, edible oil and n-hexane. The preparation process of the oil-water separation membrane is simple, the cost is low, and the reaction condition is mild; when the oil-water separation membrane is applied to organic wastewater separation, the oil-water separation membrane has the advantages of high efficiency, good removal performance and good recycling performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of membrane separation technology, and particularly relates to a preparation method of a hydrophilic oil-water separation anti-fouling membrane, the anti-fouling membrane and application thereof. BACKGROUND

[0002] With the rapid development of industrial society, the discharge amount of oily wastewater increases sharply, which is mainly generated in various industrial production processes (including petroleum chemical industry, machinery manufacturing, metal smelting and other industries). As a common pollution, oily wastewater pollution is extremely harmful to environmental protection and ecological balance. If it is not treated before entering the water body, it will cause greater harm to the environment than other types of oil-water because of its special physical and chemical properties.

[0003] In recent years, the demand for materials capable of effectively and quickly separating oil-water mixtures and oil-water emulsions has rapidly increased.

[0004] So far, existing oil-water separation technologies can be divided into the following categories: for example, suspended gravity treatment method, centrifugal deposition method, biological treatment and electrodeposition. However, these technologies have more or less the following shortcomings, such as low separation efficiency, high separation cost, easy secondary pollution problem, etc., which greatly limits their application.

[0005] Recent studies have shown that oil-water separation materials based on membranes have been proven to have good application prospects for oil-water separation, but their performance is poor and difficult to promote application. SUMMARY

[0006] This section aims to summarize some aspects of the embodiments of the application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the application.

[0007] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0008] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art and provide a preparation method of a hydrophilic oil-water separation anti-fouling membrane.

[0009] To solve the above technical problems, the present application provides the following technical scheme: a preparation method of a hydrophilic oil-water separation anti-fouling membrane, comprising,

[0010] alkalization reaction of dispersing MXene in an alkaline solution, separation and collection of the precipitate obtained by the alkalization reaction, and preparation of MNRs material after water washing to neutral, drying and grinding in sequence;

[0011] The MNRs material is dispersed in dimethylacetamide, stirred uniformly, polyvinylpyrrolidone is added, and stirring is continued, and a first mixture is obtained by ultrasonic treatment;

[0012] The first mixture is mixed with polyvinylidene fluoride to obtain a second mixture, and the second mixture is stirred at 50-60℃;

[0013] The treated second mixture is dip-coated on a carrier, and the dip-coated carrier is placed in deionized water to obtain an ultrafiltration membrane;

[0014] The obtained ultrafiltration membrane is soaked in a tea polyphenol solution with Tris-HCl buffer solution, and shaken to obtain the hydrophilic oil-water separation anti-pollution membrane.

[0015] As a preferred embodiment of the preparation method of the application, the alkaline solution is one of sodium hydroxide solution or potassium hydroxide solution.

[0016] As a preferred embodiment of the preparation method of the application, in the alkalization reaction, the alkalization temperature is 50-70℃, and the alkalization time is 48-72h.

[0017] As a preferred embodiment of the preparation method of the application, the MNRs material is prepared by grinding to a particle size of 1500 mesh.

[0018] As a preferred embodiment of the preparation method of the application, the material ratio of the MNRs material to dimethylacetamide is (0.1-0.9)g:40ml.

[0019] As a preferred embodiment of the preparation method of the application, in the first mixture, the material ratio of the MNRs material to polyvinylpyrrolidone is (0.1-0.9):(0-1).

[0020] As a preferred embodiment of the preparation method of the application, the first mixture is mixed with polyvinylidene fluoride to obtain a second mixture, and the ratio of the first mixture to polyvinylidene fluoride is (30-50)ml:(3-4)g.

[0021] As a preferred embodiment of the preparation method of the application, the obtained ultrafiltration membrane is soaked in a tea polyphenol solution with Tris-HCl buffer solution, which needs to be soaked in ethanol first and then placed in the buffer solution, and the pH value of the Tris-HCl buffer solution is 8.5.

[0022] Still another object of the application is to provide a hydrophilic oil-water separation anti-pollution membrane prepared by the preparation method.

[0023] Another object of the present application is to overcome the deficiencies in the prior art and provide an application of a hydrophilic oil-water separation anti-pollution film in oil-water mixture separation.

[0024] Advantages of the present application:

[0025] (1) The ultrafiltration membrane prepared by the method of the present application not only has superhydrophilic-subsuperoleophobicity, larger water flux, and higher oil-water separation efficiency compared with the hydrogel ultrafiltration membrane prepared by the traditional method, but also can achieve nearly 100% rejection effect, and the filtration flux is about 3 times that of the original PVDF membrane, showing excellent oil-water separation effect.

[0026] (2) The ultrafiltration membrane prepared by the method of the present application has excellent anti-pollution ability. The results of the anti-pollution test show that the flux recovery rate of the ultrafiltration membrane prepared by the method of the present application is close to 100% after filtering oil-water emulsion, which is higher than that of the traditional ultrafiltration membrane (unmodified treatment) which is only 70%; at the same time, the flux decay rate of the modified membrane is much lower than that of the unmodified membrane, which shows that the ultrafiltration membrane of the present application not only has high oil-water separation efficiency, but also can achieve high recovery rate and maintain the effectiveness of its own flux after oil-water separation, effectively preventing oil pollution. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0028] Figure 1 The separation mechanism diagram of the composite membrane of the present application.

[0029] Figure 2 The filtration effect diagram of the composite membrane on different types of oil.

[0030] Figure 3 The separation efficiency and flux comparison diagram of PVDF-MNRs-TP after 8 cycles of separation. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail in conjunction with the description of the present application.

[0032] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description, that the present application can be practiced with other systems, and that the present application can be practiced using different methodologies than those described herein. Therefore, the scope of the present application is indicated by the appended claims rather than by the description preceding them.

[0033] Second, the "one embodiment" or "an embodiment" referred to herein means a specific feature, structure, or characteristic under discussion that can be included in at least one implementation of the present application. The phrase "in one embodiment" as used throughout this specification does not necessarily refer to the same embodiment, though it can. In other words, unless expressly stated to the contrary, embodiments "in one embodiment" are neither mutually exclusive nor are they stand alone implementations of other embodiments.

[0034] In the present application, the MXene powder (multi-layer Ti3C2T x Acetamide, purchased from Aladdin; polyvinylpyrrolidone (PVP-K30) of superior purity, purchased from Sinopharm Group, batch number: 20190318; tea polyphenol solution of Tris-HCl buffer solution, tea polyphenol concentration is 6mol / L.

[0035] In the present application, the composite separation membrane is tested for oil-water mixture separation performance:

[0036] (1) Water flux test method: the time for 100ml pure water to pass through the composite membrane using a vacuum filtration device is used to determine the water flux of the membrane, and the specific formula is:

[0037] In the formula, V(L), A(m 2 ), and Δt(h) are the filtrate volume, effective membrane permeation area, and filtration time, respectively.

[0038] (2) Oil flux test method: the time for 100ml oil-in-water emulsion (kerosene emulsion, the preparation method is: 990mL of deionized water is added to a container, 30mg of SDS is taken as an emulsifier; then, 10mL of kerosene is added to the above solution, ultrasonic stirring for 30min, and then strong stirring for 6h to obtain a surfactant-stabilized emulsion) to pass through the composite membrane using a vacuum filtration device is used to determine the water flux of the membrane, and the specific formula is

[0039] In the formula, V(L), A(m2), Δt(h), and ΔP(bar) are the filtrate volume, effective membrane permeation area, filtration time, and transmembrane pressure, respectively.

[0040] (3) Retention rate test method: after 100ml of oil-in-water emulsion (kerosene emulsion, the preparation method is the same as above) passes through the composite membrane using a vacuum filtration device, the concentrations of the solutions before and after filtration are measured using an infrared oil measuring instrument, and the specific formula is

[0041] wherein C i (mg / L) and Co (mg / L) are the oil content in the emulsion after filtration and before filtration, respectively.

[0042] (4) Test method of flux recovery rate: the membrane after filtering 100 ml of kerosene using a vacuum filtration device is simply cleaned and then measured for water flux again, with the formula being

[0043] wherein J W1 and J W2 are the pure water fluxes before and after filtering the emulsion, respectively.

[0044] Example 1

[0045] (1) A clean beaker is taken, 100 ml of deionized water is added, 20 grams of KOH solid is weighed and dissolved therein to prepare a KOH solution with a concentration of 4 mol / L, and is left to stand.

[0046] (2) 0.1 g of MXene powder is weighed and added to the KOH solution prepared in step (1), and then it is placed on a magnetic stirrer for stirring for 72 h, with a stirring speed of 1000 rpm and a temperature of room temperature, so that the MXene undergoes a sufficient alkalization reaction.

[0047] (3) After the reaction reaches 72 h, the reacted solution is transferred to a centrifuge tube, centrifuged at a speed of 3000 rpm for 10 minutes, and then the supernatant is poured out, and the residual solid is rinsed with deionized water, followed by continued centrifugation.

[0048] The operation is repeated 3 times until the supernatant is neutral. The material washed to neutral is dried in an oven at 65°C, and then ground to 1500 mesh by a mortar to reduce its agglomeration phenomenon, and then the MNRs material is collected.

[0049] (4) 0.1 g of MNRs is dispersed in 40 ml of N-N dimethylacetamide at room temperature and magnetically stirred for 20 minutes, and then 0.1 g of polyvinylpyrrolidone is added and magnetically stirred at room temperature for 20 minutes, and then ultrasonic treatment is performed for 10 minutes to obtain a mixed solution.

[0050] (5) 3 g of polyvinylidene fluoride powder is added to the mixed solution, and then magnetically stirred at 50°C for 6 h, and after being mixed into a uniform casting solution, it is left to stand for 12 h to degas.

[0051] (6) The casting solution is slowly moved on a glass plate with a 150 um spatula, and then placed in deionized water to form a membrane, soaked for 10 minutes, and then taken out and washed to obtain an ultrafiltration membrane.

[0052] (7) Put the ultrafiltration membrane into the tea polyphenol solution with Tris-HCl buffer at pH 8.5 and gently shake for 12 h to obtain an oil-water separation membrane.

[0053] Example 2

[0054] (1) Take a clean beaker, add 100 ml of deionized water, weigh 20 grams of KOH solid and dissolve it to prepare a KOH solution with a concentration of 4 mol / L, and stand still.

[0055] (2) Weigh 0.1 g of MXene powder into the KOH solution prepared in step (1), and then place it on a magnetic stirrer for stirring for 72 h, with a speed of 1000 rpm and a temperature of room temperature to make the MXene undergo a full alkalization reaction.

[0056] (3) After 72 h of reaction, transfer the reacted solution to a centrifuge tube, centrifuge at a speed of 3000 rpm for 10 minutes, then pour out the supernatant, and rinse the remaining solid with deionized water, then continue to centrifuge.

[0057] Repeat the operation 3 times until the supernatant is neutral. Dry the material washed to neutral in an oven at 65°C, then grind to 1500 mesh with a mortar to reduce its agglomeration phenomenon, and then collect the MNRs material.

[0058] (4) Disperse 0.2 g of MNRs in 40 ml of N-N dimethylacetamide at room temperature and magnetically stir for 30 minutes, then add 0.1 g of polyvinylpyrrolidone and continue to magnetically stir at room temperature for 30 minutes, then ultrasonic treatment for 20 minutes to obtain a mixed solution.

[0059] (5) Add 3 g of polyvinylidene fluoride powder to the mixed solution and then magnetically stir at 50°C for 7 h, mix into a uniform casting solution, and stand still for 14 h to degas.

[0060] (6) Slowly move the casting solution on a glass plate with a 150 um spatula, then place it in deionized water to form a membrane, soak for 15 minutes, then take it out and wash it to obtain an ultrafiltration membrane.

[0061] (7) Put the ultrafiltration membrane into the tea polyphenol solution with Tris-HCl buffer at pH 8.5 and gently shake for 12 h to obtain an oil-water separation membrane.

[0062] The comparison chart of separation efficiency and flux of PVDF-MNRs-TP membrane after 8 cycles of separation is shown in Figure 3 It can be seen that the PVDF-MNRs-TP membrane has good cycle performance.

[0063] Example 3

[0064] (1) Take a clean beaker, add 100 ml of deionized water, weigh 20 grams of KOH solid and dissolve it in it to prepare a KOH solution with a concentration of 4 mol / L, and stand still.

[0065] (2) Weigh 0.1 g of MXene powder into the KOH solution prepared in step (1), then place it on a magnetic stirrer and stir for 72 h at a speed of 1000 rpm and room temperature to allow the MXene to undergo a full alkalization reaction.

[0066] (3) After 72 h of reaction, transfer the reacted solution to a centrifuge tube, centrifuge at 3000 rpm for 10 minutes, then pour out the supernatant, rinse the remaining solids with deionized water, and then continue centrifuging.

[0067] Repeat operation 3 times until the supernatant is neutral. Dry the material washed to neutral in an oven at 65°C, then grind it to 1500 mesh in a mortar to reduce its agglomeration, and then collect the MNRs material.

[0068] (4) Disperse 0.3 g of MNRs in 40 ml of N-N dimethylacetamide at room temperature and magnetically stir for 40 minutes, then add 0.1 g of polyvinylpyrrolidone and continue to magnetically stir at room temperature for 40 minutes, then ultrasonic treatment for 30 minutes to obtain a mixed solution.

[0069] (5) Add 3 g of polyvinylidene fluoride powder to the mixed solution and then magnetically stir at 60°C for 8 h, mix into a uniform casting solution, and then stand still for 16 h to degas.

[0070] (6) Slowly move the casting solution on a glass plate with a 150 um spatula, then place it in deionized water to form a membrane, soak for 20 minutes, then take it out and wash it to obtain an ultrafiltration membrane.

[0071] (7) Place the ultrafiltration membrane in a tea polyphenol solution with a Tris-HCl buffer at pH 8.5 and gently shake for 16 h to obtain an oil-water separation membrane.

[0072] Take the PVDF-MNRS-TP composite separation membrane prepared in Example 1 to test its oil-water mixture separation performance, using edible oil, n-hexane, kerosene, and petroleum ether as oil-in-water emulsions (add 990 mL of deionized water to the container, take 30 mg of SDS as an emulsifier; then, add 10 mL of the corresponding oil to the above solution, ultrasonic stir for 30 min, and then strong stirring for 6 h to obtain a surfactant-stable emulsion), and the composite membrane separation mechanism diagram is shown in Figure 1 , for example Figure 2 It can be concluded that the PVDF-MNRs-TP composite separation membrane has good separation efficiency.

[0073] The PVDF-MNRS-TP composite separation membrane prepared in the example was taken to test its water flux, oil filtration effect and flux recovery rate as shown in Table 1.

[0074] Table 1

[0075]

[0076] Comparative Example 1

[0077] On the basis of Example 2, MNRs material was not prepared, and MXene powder was directly added to prepare the membrane, and other conditions were the same as those in Example 2.

[0078] Comparative Example 2

[0079] On the basis of Example 2, tea polyphenol solution was not added, and the ultrafiltration membrane was directly placed in Tris-HCl buffer with a pH of 8.5, and other conditions were the same as those in Example 2.

[0080] Comparative Example 3

[0081] On the basis of Example 2, polyvinylpyrrolidone was not added, and other conditions were the same as those in Example 2.

[0082] The water flux, oil filtration effect and flux recovery rate were tested as shown in Table 2.

[0083] Table 2

[0084]

[0085] As can be seen from Table 2, the PVDF-MNRS-TP composite separation membrane prepared in Example 2 was taken to test the oil-water mixture separation performance with Comparative Examples 1, 2 and 3, and kerosene was used as an oil-in-water emulsion. As shown in Table 2, the PVDF-MNRs-TP greatly improved the oil-water separation performance and the stability of the membrane due to the loose fibrous structure of the MNRs material and the stable tea polyphenol layer double-loaded on the membrane.

[0086] Comparative Example 4

[0087] On the basis of Example 2, the ratio of MNRs material, polyvinylpyrrolidone and polyvinylidene fluoride was compared, and the specific conditions differed in steps (3) and (4), which were as follows:

[0088] Test 1:

[0089] 0.1 g of MNRs was dispersed in 40 ml of N-N dimethylacetamide at room temperature and magnetically stirred for 30 minutes, then 0.2 g of polyvinylpyrrolidone was added and magnetically stirred at room temperature for another 30 minutes, and then ultrasonic treatment was performed for 20 minutes to obtain a mixed solution;

[0090] 3g of polyvinylidene fluoride powder was added to the mixed solution and then magnetically stirred at 50℃ for 7h, and after mixing into a uniform casting solution, it was left to stand for 14h to remove bubbles.

[0091] Test 2:

[0092] 0.2g of MNRs was dispersed in 40ml of N-N dimethylacetamide and magnetically stirred at room temperature for 30min, then 0.1g of polyvinylpyrrolidone was added and magnetically stirred at room temperature for another 30min, and then ultrasonic treatment was carried out for 20min to obtain a mixed solution;

[0093] 1.5g of polyvinylidene fluoride powder was added to the mixed solution and then magnetically stirred at 50℃ for 7h, and after mixing into a uniform casting solution, it was left to stand for 14h to remove bubbles.

[0094] Test 3:

[0095] 0.2g of MNRs was dispersed in 40ml of N-N dimethylacetamide and magnetically stirred at room temperature for 30min, then 0.1g of polyvinylpyrrolidone was added and magnetically stirred at room temperature for another 30min, and then ultrasonic treatment was carried out for 20min to obtain a mixed solution;

[0096] 3.6g of polyvinylidene fluoride powder was added to the mixed solution and then magnetically stirred at 50℃ for 7h, and after mixing into a uniform casting solution, it was left to stand for 14h to remove bubbles.

[0097] The water flux, oil filtration effect and flux recovery rate were tested, as shown in Table 3.

[0098] Table 3

[0099]

[0100] As can be seen from Table 3, the addition amount of polyvinylpyrrolidone cannot be too high, and if it exceeds the range, the pores of the membrane will become more, thereby reducing the oil blocking effect; if the addition amount of polyvinylidene fluoride powder is too small, the proportion of the loaded material will increase, thereby making the membrane surface dense and reducing the water and oil flux, so the addition proportion of various materials needs to be controlled.

[0101] The preparation method of the hydrophilic oil-water separation membrane provided by the application mainly has the following principles: in the pore forming mode, a pore forming agent polyvinylpyrrolidone is used to form pores, and particles are embedded in the pore positions of the membrane. In addition, the MNRs material has a loose fibrous structure, which can better adsorb the tea polyphenol coating, so that the coating will not be lost due to the number of filtrations, and the interaction between the two networks improves the oil blocking efficiency, so that the prepared membrane can achieve good effects in oil-water separation.

[0102] The technical problem to be solved by the present application is to provide a novel hydrophilic polyvinylidene fluoride oil-water separation membrane and a preparation method thereof, the method has simple preparation process, low material price, is suitable for industrial production, the obtained hydrophilic polyvinylidene fluoride flat membrane has the characteristics of high strength and high flux, the flux is stable in the oil-water separation process, the separation performance is excellent, and has wide industrial application value in oil-water separation, sewage treatment and marine oil leakage.

[0103] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the present application.

Claims

1. A method for preparing a hydrophilic oil-water separation anti-fouling membrane, characterized in that: The preparation method comprises the following steps: alkalization reaction of dispersing MXene in an alkaline solution, separation and collection of the precipitate obtained in the alkalization reaction, drying and grinding after water washing to neutralization; dispersing the MNRs material in dimethylacetamide, stirring uniformly, adding polyvinylpyrrolidone, continuing to stir, and obtaining a first mixture by ultrasonic treatment, the material ratio of the MNRs material to dimethylacetamide being 0.2 g:40 mL, and the ratio of the MNRs material to polyvinylpyrrolidone being 0.2 g:0.1 g; mixing the first mixture with polyvinylidene fluoride to obtain a second mixture, stirring the second mixture at 50-60℃, and the ratio of the MNRs material to polyvinylidene fluoride being 0.2 g:3 g; immersing the treated second mixture on a carrier, and placing the immersed carrier in a glass sheet and deionized water to obtain an ultrafiltration membrane; immersing the obtained ultrafiltration membrane in a tea polyphenol solution of Tris-HCl buffer solution, and shaking to obtain the hydrophilic oil-water separation anti-pollution membrane, and the tea polyphenol concentration in the tea polyphenol solution of Tris-HCl buffer solution being 6 mol / L.

2. The production method according to claim 1, characterized by: The alkaline solution is one of a sodium hydroxide solution or a potassium hydroxide solution.

3. The production method according to claim 1 or 2, characterized by: The alkalization reaction, wherein the alkalization temperature is 50-70℃, and the alkalization time is 48-72 h.

4. The production method according to claim 3, characterized by: The grinding to obtain the MNRs material, wherein the grinding is to a particle size of 1500 mesh.

5. The production method according to claim 1, wherein: The immersion of the obtained ultrafiltration membrane in the tea polyphenol solution of Tris-HCl buffer solution needs to be immersed in ethanol first and then placed in the buffer solution, and the pH value of the Tris-HCl buffer solution is 8.

5.

6. The hydrophilic oil-water separation anti-pollution membrane prepared by the preparation method in any one of claims 1-5.

7. The application of the oil-water separation anti-pollution membrane in claim 6 in oil-water mixture separation.

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