Modified carbon nanotube and macene composite doped polyether sulfone membrane and preparation method thereof

Abstract

The application discloses a modified carbon nanotube and mackinaw cloth composite doped polyether sulfone membrane and a preparation method thereof, and the preparation method comprises the following steps: step 1, combining MWCNTs and EGCG by using a non-covalent grafting method to prepare E-MWCNTs; step 2, performing amino functionalization on Mxene by using AEAPTMS to obtain A-Mxene; and step 3, preparing a PES mixed matrix membrane with E-MWCNTs and A-Mxene as dopants by using a phase inversion method. The polyether sulfone water treatment membrane can efficiently remove dirt through electric assistance in the use process, can achieve a high flux recovery rate, can prevent bacterial pollution, can prolong the service life of the membrane and can reduce the cost.

Description

Technical Field

[0001] This invention relates to the field of separation membrane modification technology, and in particular to a modified carbon nanotube and MICRE composite doped polyethersulfone membrane and its preparation method. Background Technology

[0002] Currently, due to the excessive discharge of industrial and agricultural wastewater, the world is facing a problem of per capita water scarcity, which has led to an increasingly tense situation regarding water resource utilization. To address this issue, water recycling is necessary. Membrane separation technology, which involves sieving mixtures of molecules with different particle sizes, is a practical solution for water reuse. However, membrane fouling has always been a common problem in membrane separation processes.

[0003] In recent years, the combination of membranes and applied electric fields has been widely used in wastewater treatment to improve retention rates or pollutant removal rates. Fouling in water (such as bacteria and natural organic matter) is typically negatively charged; applying an external voltage to make the membrane surface negatively charged can improve the electrostatic repulsion between the membrane and the fouling. Furthermore, this process generates bubbles similar to gas scrubbing, effectively removing membrane fouling. Therefore, researchers urgently need to develop a stable, easily fabricated conductive ultrafiltration membrane.

[0004] Multi-walled carbon nanotubes (MWCNTs) and MXenes are widely used in water treatment membranes due to their excellent conductivity, high mechanical strength, large specific surface area, and good stability. However, both pristine carbon nanotubes and MXenes carry a negative charge, resulting in weak binding forces, which is a problem that needs to be solved. Therefore, how to provide a modified carbon nanotube and MXene-doped polyethersulfone (PES) membrane and its preparation method to improve membrane performance and achieve high-efficiency fouling removal is a problem that researchers in this field still need to solve. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies of existing carbon nanomaterial-doped water treatment membranes by providing a polyethersulfone membrane composite-doped with modified carbon nanotubes and MICRE.

[0006] Another object of the present invention is to provide a method for preparing the polyethersulfone film co-doped with the modified carbon nanotubes and micene.

[0007] The technical solution adopted to achieve the purpose of this invention is:

[0008] A method for preparing a polyethersulfone film co-doped with modified carbon nanotubes and MICRE includes the following steps:

[0009] Step 1: E-MWCNTs were prepared by combining MWCNTs and epigallocatechin gallate (EGCG) using a non-covalent grafting method.

[0010] Step 2: Mxene is amino-functionalized using [3-(2-aminoethylamino)-propyl]trimethoxysilane (AEAPTMS) to obtain A-Mxene;

[0011] Step 3: Prepare polyethersulfone films with E-MWCNTs and A-Mxene as dopants using the phase inversion method.

[0012] In the above technical solution, in step 1, firstly, MWCNTs and EGCG are ultrasonically dispersed to obtain a uniform suspension, mechanically stirred, and then the suspension is filtered, washed, dried, and ground to obtain E-MWCNTs.

[0013] In the above technical solution, in step 1, the mass ratio of MWCNTs to EGCG is 1:(2-7.5);

[0014] The ultrasound duration is 30-60 minutes, and the ultrasound power is 180-250W.

[0015] The mechanical stirring is carried out in a magnetic stirrer with a rotation speed of 500-700 rpm and a stirring time of 12-36 hours.

[0016] The suspension was filtered and washed three times with alcohol during the filtration process;

[0017] The drying process is carried out in a vacuum oven at room temperature for 6–24 hours.

[0018] In the above technical solution, in step 2, under the protection of a protective gas, MXene and [3-(2-aminoethylamino)-propyl]trimethoxysilane (AEAPTMS) are added to a water / ethanol mixed solution, the pH of the reaction medium is adjusted to 3.5 with hydrochloric acid, and mechanical stirring is performed. After the reaction is completed, the suspension is filtered and washed, and the resulting filter cake is dried and ground to obtain A-Mxene.

[0019] In the above technical solution, in step 2, the mass ratio of MXene and AEAPTMS is 1:2;

[0020] The mass ratio of the water / ethanol mixture is 1:9;

[0021] The mechanical stirring is carried out in a magnetic stirrer at a speed of 500-700 rpm for a mixing time of 6-12 hours.

[0022] The drying process is carried out in a vacuum oven at room temperature for 6–24 hours.

[0023] In the above technical solution, in step 3, E-MWCNTs and A-MXene are first dispersed in N,N-dimethylacetamide (DMAc) solvent at a predetermined ratio, and sonicated to ensure uniform suspension of the dopants to obtain a suspension. Then, PES and polyvinylpyrrolidone (PVP) are slowly added to the suspension under stirring to obtain a casting solution. Mechanical stirring is maintained to remove air bubbles in the casting solution. Then, the casting solution is poured onto a clean glass plate using a scraper and a film is scraped with a scraper to obtain an initial film. The initial film is evaporated at room temperature for a predetermined time and then immersed in a water bath for phase transformation to obtain a polyethersulfone film with modified carbon nanotubes and MXene composite doping.

[0024] In the above technical solution, in step 3, the content of E-MWCNTs in the casting solution is 0-0.75%, the content of A-MXene is 0-0.1%, the content of DMAc solvent is 79.25-80%, the content of PVP is 1%, and the content of PES is 19%.

[0025] The ultrasound duration is 30-60 minutes, and the ultrasound power is 180-250W.

[0026] The stirring is carried out in a magnetic stirrer at a speed of 500-700 rpm for a mixing time of 6-10 hours.

[0027] The thickness of the scraper is 150-200μm.

[0028] Another aspect of the present invention includes a polyethersulfone film co-doped with modified carbon nanotubes and micene obtained by the preparation method described above.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention uses a phase inversion method to dope E-MWCNTs and A-MXene to prepare a PES water treatment membrane, which has the advantages of simple preparation, excellent permeability and separation performance, good conductivity and excellent antibacterial properties.

[0031] 2. The modified surfaces of E-MWCNTs and A-MXene have opposite charges, which can promote electrostatic bonding, alleviate aggregation, and make the composite of the two in the membrane more stable.

[0032] 3. The polyethersulfone water treatment membrane of the present invention can efficiently remove dirt through electrical assistance during use, achieve a high flux recovery rate, prevent bacterial contamination, extend the membrane's working life, and reduce costs. Attached Figure Description

[0033] Figure 1Transmission electron microscope (TEM) images of E-MWCNTs provided for this invention.

[0034] Figure 2 Transmission electron microscope image of A-MXene provided by this invention.

[0035] Figure 3 Cross-sectional structure scanning electron microscope images of pure PES membranes and modified membranes provided for this invention

[0036] Figure 4 Bar chart showing the pure water flux of the pure PES membrane and the modified membrane provided by this invention.

[0037] Figure 5 The bar chart shows the flux recovery rates of the pure PES membrane and the modified membrane provided by this invention. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0039] The reagents and materials used in this invention, including MWCNTs, EGCG, PVP, DMAc, PES, Congo red dye, and bovine serum albumin, were all of analytical grade.

[0040] Example 1

[0041] A modified carbon nanotube and MICRE composite-doped polyethersulfone film is prepared by the following steps:

[0042] Step 1: MWCNTs and EGCG at a mass ratio of 1:5 were ultrasonically dispersed at 200W for 60 minutes to obtain a uniform suspension. This suspension was then mechanically stirred in an oil bath for 24 hours. Afterward, the suspension was filtered and washed three times with alcohol during the filtration process. Finally, the resulting filter cake was dried in a vacuum drying oven at room temperature for 12 hours, then ground for use.

[0043] Step 2: MXene and [3-(2-aminoethylamino)-propyl]trimethoxysilane (AEAPTMS) in a mass ratio of 1:2 were added to a water / ethanol mixture and stirred. Nitrogen gas was introduced for protection during the reaction, and the pH of the reaction medium was adjusted to 3.5 with hydrochloric acid. During filtration, the suspension was filtered and washed three times. Finally, the resulting filter cake was dried in a vacuum drying oven at room temperature for 24 hours and then ground.

[0044] Step 3: Add 0.75g of E-MWCNTs powder and 0.06g of A-MXene to 79.25mL of DMAc solvent and sonicate for 60min. Then add 19g of PES powder and 1g of PVP powder to the mixture and heat in an oil bath at 70℃ for 6h to prepare the casting solution. DMAc is used as the organic solvent and PVP as the pore-forming additive. First, stir the uniformly dispersed casting solution to remove some air bubbles, then place it in a vacuum oven to stand and degas. After degassing, use a 200μm doctor blade to evenly scrape the casting solution onto a clean glass plate. Then, place the glass plate smoothly and quickly into a water coagulation bath. After the phase transformation process is complete, the film automatically detaches from the glass plate, obtaining the modified film (modified carbon nanotube and A-MXene composite doped polyethersulfone film).

[0045] Comparative Example 1

[0046] 19g of PES powder and 1g of PVP powder were added to 80mL of DMAc solvent, and the casting solution was prepared by heating in an oil bath at 70℃ for 6h. DMAc was used as the organic solvent, and PVP as the pore-forming additive. The uniformly dispersed casting solution was first stirred to remove some air bubbles, and then placed in a vacuum oven for further degassing. After degassing, the casting solution was evenly coated onto a clean glass plate using a 200μm doctor blade. The glass plate was then smoothly and quickly placed in a water coagulation bath. After the phase transformation process was complete, the membrane automatically detached from the glass plate, yielding a pure PES membrane.

[0047] Example 2

[0048] Organic fouling experiments were conducted on the modified membrane obtained in Example 1 and the pure PES membrane obtained in Comparative Example 1:

[0049] In the organic fouling experiment of the membrane, Congo red (100 mg·L⁻¹) was used. -1 ) and bovine serum albumin (1 g·L -1 This was used to test the antifouling performance of the membrane. First, the pure water flux (J / m³) of the membrane was obtained at 0.1 MPa. w1 ),like Figure 4 As shown, the feed solution was then replaced with an aqueous solution of the fouling. The fouling was then removed using a membrane device powered by an external power source (voltage supplied by a DC power source, with the membrane and stainless steel serving as the cathode and anode, respectively). Finally, a physical rinse with deionized water was performed, and the pure water flux (J) was measured again. w2 ) Calculate flux recovery rate (FRR) to analyze the membrane's ability to remove fouling, such as Figure 5 As shown.

[0050] Flux recovery rate (FRR) can be calculated using the following formula:

[0051]

[0052] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a polyethersulfone film co-doped with modified carbon nanotubes and MICRE, characterized in that, Includes the following steps: Step 1: E-MWCNTs were prepared by combining MWCNTs and EGCG using a non-covalent grafting method; Step 2: Amin-functionalize Mxene using AEAPTMS to obtain A-Mxene; Step 3: Prepare polyethersulfone films with E-MWCNTs and A-Mxene as dopants using the phase inversion method.

2. The preparation method according to claim 1, characterized in that, In step 1, MWCNTs and EGCG are first ultrasonically dispersed to obtain a uniform suspension, mechanically stirred, and then the suspension is filtered, washed, dried, and ground to obtain E-MWCNTs.

3. The preparation method according to claim 2, characterized in that, In step 1, the mass ratio of MWCNTs to EGCG is 1:(2-7.5); The ultrasound duration is 30-60 minutes, and the ultrasound power is 180-250W. The mechanical stirring is carried out in a magnetic stirrer with a rotation speed of 500-700 rpm and a stirring time of 12-36 hours. The suspension was filtered and washed three times with alcohol during the filtration process; The drying process is carried out in a vacuum oven at room temperature for 6–24 hours.

4. The preparation method according to claim 1, characterized in that, In step 2, under the protection of a protective gas, MXene and AEAPTMS are added to a water / ethanol mixed solution, the pH of the reaction medium is adjusted to 3.5 with hydrochloric acid, and mechanical stirring is performed. After the reaction is completed, the suspension is filtered and washed, and the resulting filter cake is dried and ground to obtain A-Mxene.

5. The preparation method according to claim 4, characterized in that, In step 2, the mass ratio of MXene to AEAPTMS is 1:2; The mass ratio of water to ethanol in the water / ethanol mixed solution is 1:9; The mechanical stirring is carried out in a magnetic stirrer at a speed of 500-700 rpm for a mixing time of 6-12 hours. The drying process is carried out in a vacuum oven at room temperature for 6–24 hours.

6. The preparation method according to claim 1, characterized in that, In step 3, E-MWCNTs and A-MXene are first dispersed in DMAc solvent at a predetermined ratio and sonicated to ensure uniform suspension of the dopants, resulting in a suspension. Then, PES and PVP are slowly added to the suspension under stirring conditions to obtain a casting solution. Mechanical stirring is maintained to remove air bubbles from the casting solution. The casting solution is then poured onto a clean glass plate using a scraper and a film is scraped with a scraper to obtain an initial film. The initial film is evaporated at room temperature for a predetermined time and then immersed in a water bath for phase transformation to obtain a polyethersulfone film co-doped with modified carbon nanotubes and MXene.

7. The preparation method according to claim 6, characterized in that, In step 3, the casting solution contains 0-0.75% E-MWCNTs, 0-0.1% A-MXene, 79.25-80% DMAc solvent, 1% PVP, and 19% PES. The ultrasound duration is 30-60 minutes, and the ultrasound power is 180-250W. The stirring is carried out in a magnetic stirrer at a speed of 500-700 rpm for 6-10 hours. The thickness of the scraper is 150-200μm.

8. A polyethersulfone film doped with modified carbon nanotubes and micene, obtained by the preparation method according to any one of claims 1-7.

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