Heterojunction AgI / MIL-53 (Fe, Co) composite polyether sulfone film as well as preparation method and application thereof

Abstract

The invention discloses a heterojunction AgI / MIL-53 (Fe, Co) composite polyethersulfone membrane and a preparation method and application thereof. The heterojunction AgI / MIL-53 (Fe, Co) composite polyethersulfone membrane is composed of a polyethersulfone membrane, AgI modified MIL-53 (Fe, Co) nano particles loaded on the polyethersulfone membrane and a polyamide nano layer. Preparing by adopting a particle adding mode of vacuum filtration and interfacial polymerization modification; the mold material is good in permeability, high in mechanical strength and excellent in pollution resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane materials, and particularly relates to a heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, a preparation method thereof, and an application thereof. Background Art

[0002] With the research and development of science and technology, membrane separation science has become an important tool in wastewater treatment. Related excellent properties such as selectivity, high-efficiency separation, convenient operation, stability, easy integration with other processes, and cost-effectiveness make the membrane separation process the first choice for wastewater treatment. In recent years, the research and development of membrane technology have been committed to changing some physical and chemical properties of the membrane through grafting or mixing reactions, so that the material can make specific responses to specific external stimuli, such as the pore size distribution, hydrophilicity, and anti-pollution shock load of the membrane. These changes endow the membrane with high permeability, selectivity, and self-cleaning efficiency.

[0003] Polyethersulfone (PES) is a high molecular organic polymer with excellent comprehensive properties. Its glass transition temperature is as high as 225°C, and it has excellent heat resistance, alkali resistance, pressure resistance, corrosion resistance, and superior blood compatibility, etc. It is a good material for preparing various microporous membranes. However, PES membranes still have some disadvantages that need to be overcome and improved, such as poor hydrophilicity, easy membrane fouling and blockage problems during application, and easy biological fouling in biological applications.

[0004] With the development of nanotechnology, nanomaterials have become one of the main materials for membrane modification due to their special physical and chemical properties (such as hydrophilicity, antibacterial property, etc.). The organic combination of nanomaterials and membrane materials can better play the roles of both. MIL-53(Fe,Co) (metal-organic framework) is formed by infinite Fe-O clusters and 1,4-benzenedicarboxylic acid (H2BDC). Under visible light irradiation, MIL-53(Fe,Co) exhibits photocatalytic activity in the degradation of organic dyes and the reduction of CO2. However, the photocatalytic efficiency of MIL-53(Fe,Co) is relatively low, and its application is limited due to the rapid recombination of photo-generated electron-hole pairs. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, a preparation method thereof, and an application thereof. The membrane material has good permeability, high mechanical strength, and excellent anti-pollution property.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention provides a heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, and the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane is composed of a polyethersulfone membrane and AgI-modified MIL-53(Fe,Co) nanoparticles and a polyamide nanolayer supported thereon.

[0008] The present invention also provides a preparation method of the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, and the preparation method includes the following steps:

[0009] (1) Ultrasonically disperse the MIL-53(Fe,Co) material in deionized water, add a silver salt under dark conditions, stir until it is completely dissolved, and then dropwise add an aqueous solution containing I - . After the addition is completed, stir and react for 1.0 - 1.5 h, wash, dry, and grind to obtain the AgI / MIL-53(Fe,Co) material;

[0010] (2) Disperse the AgI / MIL-53(Fe,Co) material in an aqueous piperazine solution to obtain solution A;

[0011] (3) Dissolve 1,3,5-benzenetricarbonyl chloride in n-hexane to obtain solution B;

[0012] (4) Immerse the polyethersulfone membrane in a polyvinyl alcohol solution, load the immersed polyethersulfone membrane into a vacuum filtration device as a filtration membrane, then add solution A for filtration, and then add solution B for filtration to obtain the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane.

[0013] In step (1), the silver salt is one or more of AgNO3 and AgCl.

[0014] In step (1), the aqueous solution containing I - is one or more of an aqueous KI solution and an aqueous NaI solution.

[0015] In step (1), the mass ratio of the MIL-53(Fe,Co) material to the silver salt is 1:0.1 - 0.5; the molar ratio of the silver salt to I - in the aqueous solution containing I - is 1:1 - 1.2.

[0016] In step (2), the mass ratio of the AgI / MIL-53(Fe,Co) material to piperazine is 0.1 - 0.3:4; the mass concentration of the aqueous piperazine solution is 0.001 - 0.005 wt%.

[0017] In step (3), the mass ratio of 1,3,5-benzenetricarbonyl chloride to n-hexane is 0.1 - 0.3:100.

[0018] In step (4), the mass concentration of the polyvinyl alcohol solution is 0.5-1.0 wt%; the volume ratio of solution A to solution B is 1:1.

[0019] The present invention also provides the application of the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane as a membrane material for treating wastewater.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) In the preparation method of the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane provided by the present invention, MIL-53(Fe,Co) with a relatively large specific surface area is selected as the composite substrate of silver iodide (AgI), which improves the separation rate of photo-generated carriers of the catalyst.

[0022] (2) The particle addition method of vacuum filtration and interfacial polymerization modification has small operation difficulty, easy operation control, and small floor area.

[0023] (3) The anti-pollution performance of the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane prepared by the method of the present invention is significantly improved. The present invention modifies the polyethersulfone membrane to form a polyamide layer that is not easy to bond and deposit pollutants and antibacterial AgI particles on the membrane surface, thereby effectively alleviating the membrane pollution problem and extending the service life of the membrane. Description of the Drawings

[0024] Figure 1 It is the SEM image of the AgI / MIL-53(Fe,Co) material in Example 1;

[0025] Figure 2 It is the TEM image of the AgI / MIL-53(Fe,Co) material in Example 1;

[0026] Figure 3 It is the XRD image of the AgI / MIL-53(Fe,Co) material in Example 1;

[0027] Figure 4 It is the XPS image of the AgI / MIL-53(Fe,Co) particles in Example 1;

[0028] Figure 5 It is the SEM image of the membrane materials prepared in each example and comparative example;

[0029] Figure 6 It is the pure water flux image of the membrane materials prepared in each example and comparative example;

[0030] Figure 7 It is the pollutant interception change image of the membrane materials prepared in each example and comparative example;

[0031] Figure 8 It is the preparation flow chart of the AgI / MIL-53(Fe,Co) material;

[0032] Figure 9 It is the preparation flow chart of the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane. Specific embodiments

[0033] The present invention will be described in detail below in conjunction with embodiments.

[0034] The preparation method of the AgI / MIL-53(Fe,Co) material used in the embodiment is as follows: Terephthalic acid, ferric chloride hexahydrate, and cobalt nitrate hexahydrate are dissolved in 60 mL of N,N-dimethylformamide according to a molar ratio of 1:1:280, ultrasonic oscillation is carried out for 30 min, and then magnetic stirring is carried out for 1 h. The completely dissolved mixture is transferred to a 100 mL Teflon-lined stainless steel autoclave reactor and heated at 150 °C for 15 h. After natural cooling to room temperature, the obtained precipitate is collected by centrifugation, washed 5 times with DMF and anhydrous methanol respectively. Finally, the sample is dried overnight at 60 °C. The MIL-53(Fe,Co) material is ultrasonically dispersed in deionized water. Under dark conditions, a silver salt is added and stirred until it is completely dissolved, and then an aqueous solution containing I- is added dropwise. After the addition is completed, the reaction is stirred for 5-6 h. After washing, drying, and grinding, the AgI / MIL-53(Fe,Co) material is obtained;

[0035] Example 1 (particles 0.3 wt%)

[0036] A preparation method of a heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane includes the following steps:

[0037] (1) 0.1 g of the MIL-53(Fe,Co) material is ultrasonically dispersed in 100 mL of deionized water. Under dark conditions, 0.0141 g of KI is added and stirred until it is completely dissolved, and then 1 mL of an aqueous AgNO3 solution with a mass concentration of 0.0144 g / mL is added dropwise. After the addition is completed, the reaction is stirred for 1.0 h. After washing with deionized water multiple times, drying, and grinding, the AgI / MIL-53(Fe,Co) material is obtained;

[0038] (2) 0.003 g of the AgI / MIL-53(Fe,Co) material is dispersed in 10 mL of an aqueous piperazine solution with a mass concentration of 0.004 g / mL to obtain solution A;

[0039] (3) 0.15 g of 1,3,5-benzenetricarbonyl chloride is dissolved in 100 g of n-hexane to obtain solution B;

[0040] (4) Immerse the polyethersulfone membrane in a polyvinyl alcohol solution with a mass concentration of 0.5 wt%, load the immersed polyethersulfone membrane into a vacuum filtration device as a filtration membrane, then add 10 mL of solution A for filtration, and then add 10 mL of solution B for filtration to obtain a heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, and its serial number is denoted as P3.

[0041] The SEM image of the AgI / MIL-53(Fe,Co) material prepared in step (1) is as Figure 1 shown. MIL-53(Fe,Co) has a well-crystallized octahedral structure and a smooth surface. After coupling with AgI, the surface morphology of the bare MOF has changed significantly. It can be clearly seen from Figure 1 that the surface of MIL-53(Fe,Co) is rough, which is caused by the adhesion of AgI particles.

[0042] The TEM image of the AgI / MIL-53(Fe,Co) material prepared in step (1) is as Figure 2 shown. The (110) crystal plane can be determined from the AgI lattice spacing of 0.229 nm. The faint fringes in MIL-53(Fe,Co) may be due to the intolerance to the electron beam.

[0043] The XRD pattern of the AgI / MIL-53(Fe,Co) material prepared in step (1) is as Figure 3 shown. In AgI, the diffraction peaks at 22.3° (110), 23.7° (002), 39.1° (110), and 46.3° (112) are the main diffraction peaks. In AgI / MIL-53(Fe,Co), due to the loading of AgI, some obvious new diffraction peaks appear. Due to the loading of AgI, the diffraction changes more significantly between 20° and 50°. The peak intensity increases with the increase of the AgI content, verifying the successful preparation of AgI / MIL-53(Fe,Co).

[0044] The XPS pattern of the AgI / MIL-53(Fe,Co) material prepared in step (1) is as Figure 4As shown, XPS, C1s, O1s, Fe2p, Co2p, Ag3d, and I3d in the AgI / MIL-53(Fe,Co) spectrum were used for analysis. Compared with MIL-53(Fe,Co), the positions of C1s at 288.56 eV and 284.8 eV shifted to 288.60 eV and 284.75 eV, indicating that the symmetric and asymmetric vibrations of the benzene ring and carboxyl group were affected by AgI nanoparticles. The peak intensity of the C1s diffraction peak was affected by the high crystallinity of AgI. For O1s, the peak at 531.76 eV shifted to 531.81 eV, indicating that the binding energy of -COOH was affected by AgI nanoparticles. This provided more possibilities for the loading of AgI. From the perspective of Fe, the electronic configuration of Fe was affected by AgI nanoparticles, and the Fe2p 1 / 2 and Fe2p 3 / 2 peaks shifted to 724.76 eV and 711.58 eV, indicating that the coordination of H2BDC with Fe was affected by AgI nanoparticles. The XPS spectrum of MIL-53(Fe,Co) confirmed the presence of Fe and Co, indicating the successful incorporation of Co. In the high-resolution spectrum of Co 2p, the peaks at 797.27 eV and 782.06 eV shifted to 796.99 eV and 782.13 eV, indicating that the oxidation state of Co in MIL-53(Fe / Co) and MIL-53(Co)28 was +2. In addition, the characteristic peaks at 374.24 eV and 368.24 eV corresponded to Ag 3d 3 / 2 and Ag 3d 5 / 2 , and the characteristic peaks at 630.90 eV and 619.43 eV corresponded to I3d 3 / 2 and I 3d 5 / 2 , so Ag+ combined with I- to form AgI. These results indicate that a tight contact interface was established between MIL-53(Fe,Co) and AgI nanoparticles, verifying the formation of a heterostructure between AgI and MIL-53(Fe,Co).

[0045] Example 2 (0.2 wt% of particles)

[0046] A method for preparing a heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, comprising the following steps:

[0047] (1) The same as Example 1;

[0048] (2) Disperse 0.002 g of AgI / MIL-53(Fe,Co) material in 10 mL of an aqueous piperazine solution with a mass concentration of 0.004 g / mL to obtain Solution A;

[0049] (3) Dissolve 0.15 g of 1,3,5-benzenetricarbonyl chloride in 100 g of n-hexane to obtain Solution B;

[0050] (4) Immerse the polyethersulfone membrane in a polyvinyl alcohol solution with a mass concentration of 0.5 wt%. After immersion, load the polyethersulfone membrane into a vacuum filtration device as a filtration membrane. Then, add 10 mL of Solution A for filtration, and then add 10 mL of Solution B for filtration to obtain the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, which is numbered as P2.

[0051] Example 3 (0.1 wt% of particles)

[0052] A method for preparing a heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, comprising the following steps:

[0053] (1) The same as Example 1;

[0054] (2) Disperse 0.001 g of AgI / MIL-53(Fe,Co) material in 10 mL of an aqueous piperazine solution with a mass concentration of 0.004 g / mL to obtain Solution A;

[0055] (3) Dissolve 0.15 g of 1,3,5-benzenetricarbonyl chloride in 100 g of n-hexane to obtain Solution B;

[0056] (4) Immerse the polyethersulfone membrane in a polyvinyl alcohol solution with a mass concentration of 0.5 wt%. After immersion, load the polyethersulfone membrane into a vacuum filtration device as a filtration membrane. Then, add 10 mL of Solution A for filtration, and then add 10 mL of Solution B for filtration to obtain the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane, which is numbered as P1.

[0057] Comparative Example 1 (0 wt% of particles)

[0058] A method for preparing a polyethersulfone membrane, comprising the following steps

[0059] (1) Dissolve 0.15 g of 1,3,5-benzenetricarbonyl chloride in 100 g of n-hexane to obtain Solution B;

[0060] (2) Immerse the polyethersulfone membrane in a polyvinyl alcohol solution with a mass concentration of 0.5 wt%. After immersion, load the polyethersulfone membrane into a vacuum filtration device as a filtration membrane. Then, add 10 mL of an aqueous piperazine solution for filtration, and then add 10 mL of Solution B for filtration to obtain a polyethersulfone membrane, which is numbered as P0.

[0061] Comparative Example 2

[0062] A method for preparing a heterojunction AgI / MIL-53 (Fe, Co) composite polyethersulfone membrane comprises the following steps:

[0063] (1) Same as Example 1;

[0064] (2) 0.003 g of AgI / MIL-53 (Fe, Co) material was dispersed in 10 mL of a 0.004 g / mL piperazine aqueous solution to obtain solution A;

[0065] (3) The polyethersulfone membrane was soaked in a polyvinyl alcohol solution with a mass concentration of 0.5 wt%. The soaked polyethersulfone membrane was placed in a vacuum filtration device as a filtration membrane, and then 10 mL of solution A was added for filtration to obtain a polyethersulfone membrane, which was numbered P. m .

[0066] Test Example 1

[0067] The pure water flux of the membrane materials prepared in Examples 1 to 3 and Comparative Example 1 was tested using an SCM ultrafiltration cup as the main instrument. Before the test, the membrane was pre-pressed at a pressure of 0.15 MPa for 30 minutes, and the pure water flux was tested at 0.1 MPa.

[0068] The results are as follows Figure 6 As shown in the figure, it can be seen that with the increase of the mass fraction of AgI / MIL-53(Fe,Co) material, the pure water flux shows a decreasing trend, and the retention rate of the membrane for pollutants gradually increases. It can be seen that the loading of AgI / MIL-53(Fe,Co) material improves the filtration performance of the membrane.

[0069] Test Example 2

[0070] The membrane was cut into pieces that matched the size of the SCM300 ultrafiltration cup and pre-pressed at 0.15 MPa for 30 minutes. The cup wall and the membrane were initially rinsed with 1000 ppm of specific pollutant solution (BSA and HA), and then a pollutant filtration test was performed. The pollutant concentration in the filtrate after 30 minutes was determined by UV spectrophotometry to explore the retention performance of the new composite membrane.

[0071] The results are as follows Figure 7As shown in the figure, it can be seen that with the increase of the mass fraction of AgI / MIL-53 (Fe, Co) material, the rejection rate of the membrane for pollutants gradually increases. At the optimal dosage of AgI / MIL-53 (Fe, Co) material (0.3wt%), the membrane has the best removal rates of two model organic pollutants (BSA and HA) of up to 90% and 98% respectively. From the comparison between Example 1 and Comparative Example 2, it can be seen that if only AgI / MIL-53 (Fe, Co) material is loaded on the polyethersulfone membrane without adding solution B, the separation and retention effect of the membrane for pollutants will deteriorate. It can be seen that the improvement in the retention rate is attributed to the fact that the polyamide layer enhances the separation and retention of the membrane for pollutants. It can be seen that the heterojunction AgI / MIL-53 (Fe, Co) composite polyethersulfone membrane provided by the present invention has a good pollutant retention effect.

[0072] The detailed description of a heterojunction AgI / MIL-53 (Fe, Co) composite polyethersulfone membrane and its preparation method and application with reference to the above-mentioned embodiment is illustrative rather than restrictive. Several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A heterojunction AgI / MIL-53(Fe, Co) composite polyethersulfone membrane, characterized in that, The heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane is composed of a polyethersulfone membrane, AgI-modified MIL-53(Fe,Co) nanoparticles loaded thereon, and a polyamide nanolayer.

2. The preparation method of the heterojunction AgI / MIL-53(Fe, Co) composite polyethersulfone membrane according to claim 1, characterized in that, The preparation method includes the following steps: (1) Ultrasonically disperse the MIL-53(Fe, Co) material in deionized water. Under dark conditions, add silver salt and stir until it completely dissolves. Then, dropwise add the aqueous solution containing I - . After the addition is complete, stir and react for 5 - 6 h. After washing, drying, and grinding, obtain the AgI / MIL-53(Fe, Co) material; (2) Disperse the AgI / MIL-53(Fe,Co) material in an aqueous piperazine solution to obtain Solution A; (3) Dissolve 1,3,5-benzenetricarbonyl chloride in n-hexane to obtain Solution B; (4) Immerse the polyethersulfone membrane in a polyvinyl alcohol solution. After immersion, load the polyethersulfone membrane into a vacuum filtration device as a filtration membrane, then add Solution A for filtration, and then add Solution B for filtration to obtain the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane.

3. The preparation method according to claim 2, characterized in that, In step (1), the silver salt is one or more of AgNO3 and AgCl.

4. The preparation method according to claim 2, characterized in that, In step (1), the aqueous solution containing I - is one or more of KI aqueous solution and NaI aqueous solution.

5. The preparation method according to claim 2, characterized in that, In step (1), the mass ratio of the MIL-53(Fe,Co) material to the silver salt is 1:0.1 to 0.5; the molar ratio of the silver salt to I in the aqueous solution containing I - is 1:1 to 1.

2. - ​ 6. The preparation method according to claim 2, characterized in that, In step (2), the mass ratio of the AgI / MIL-53(Fe,Co) material to piperazine is 0.1-0.3:4; the mass concentration of the aqueous piperazine solution is 0.001-0.005 wt%.

7. The preparation method according to claim 2, wherein In step (3), the mass ratio of 1,3,5-benzenetricarbonyl chloride to n-hexane is 0.1-0.3:

100.

8. The preparation method according to claim 2, characterized in that, In step (4), the mass concentration of the polyvinyl alcohol solution is 0.5-1.0 wt%; the volume ratio of Solution A to Solution B is 1:

1.

9. Use of the heterojunction AgI / MIL-53(Fe,Co) composite polyethersulfone membrane as claimed in claim 1 as a membrane material for treating wastewater.

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