Preparation method of silver-loaded antibacterial polyamide composite membrane

Abstract

The invention relates to a preparation method of a membrane material, in particular to a preparation method of a silver-loaded antibacterial polyamide composite membrane. Polyamide modification is carried out on the outer portions of the porous silver particles, then the outer surface of the polyamide composite membrane is coated with the modified porous silver particles, amidogen of a polyamide shell and acyl chloride on the surface of the polyamide composite membrane form amido bond bonding, and therefore the stability of the anti-pollution composite membrane is improved on the basis that the anti-pollution capacity of the silver particles is basically not reduced.

Description

Technical Field

[0001] The present invention relates to a method for preparing a membrane material, and specifically to a method for preparing a silver-loaded antibacterial polyamide composite membrane. Background Art

[0002] With the rapid development of industrialization and urbanization, the problems of water resource pollution and water quality decline have become increasingly serious. Traditional water treatment methods often struggle to meet people's demand for high-quality water resources. Membrane separation technology, represented by reverse osmosis and nanofiltration, as an efficient membrane separation technology, has been widely applied in the field of water treatment. However, traditional reverse osmosis membranes are prone to contamination by bacteria, microorganisms, etc., leading to a decline in the membrane's permeability and separation efficiency, and even potentially causing secondary pollution.

[0003] To address this issue, antibacterial polyamide composite reverse osmosis membranes have emerged. By introducing antibacterial agents, such as silver nanoparticles, and compounding them with polyamide membranes, antibacterial properties are imparted to the reverse osmosis membranes. Such composite membranes can not only effectively filter out impurities, heavy metals, and harmful substances in water but also inhibit the growth of bacteria on the membrane surface, maintaining the membrane's permeability and service life. In the prior art, silver particles are usually loaded on the surface of polyamide composite membranes when introducing silver particles into polyamide composite membranes, but there are problems with the loading stability of silver particles. There is also prior art in which silver particles are directly or placed in an organic shell structure and blended in the middle of polyamide composite membranes, but the antibacterial and anti-pollution ability of silver particles inside the membrane decreases, and there are compatibility problems between the organic shell and the polyamide composite membrane, thus affecting the membrane quality. Therefore, there has been no good solution to the above problems in the field of membrane preparation. Summary of the Invention

[0004] The present invention provides a method for preparing a silver-loaded antibacterial polyamide composite membrane. By modifying the outside of porous silver particles with polyamide and then coating it on the outer surface of the polyamide composite membrane, the amino group of the polyamide shell forms an amide bond with the acyl chloride on the surface of the polyamide composite membrane, thereby achieving an improvement in the stability of the anti-pollution composite membrane on the basis of basically not reducing the anti-pollution ability of silver particles.

[0005] Specifically, the present invention provides a method for preparing a silver-loaded antibacterial polyamide composite membrane, which is characterized by including the following steps: Preparing polyamide-coated porous silver particles Successively impregnating the porous silver particles in a first oil-phase monomer solution and a first water-phase monomer solution to form porous polyamide-coated porous silver particles on the outer layer of the porous silver. After filtration and drying, soak them in an aqueous solution and continuously stir to form a modified solution for standby; Preparing a polyamide composite membrane The second aqueous monomer solution and the second oil-phase monomer solution are successively impregnated on the surface of the support, so that an interfacial polymerization is formed on the surface of the support to form a polyamide composite membrane, and it is dried at 60-80 °C; Modify the polyamide composite membrane The dissolved polyamide solution is uniformly scrape-coated on the polyamide composite membrane, and heat-treated at 40-60 °C for 0.5-1 h. Then, the polyamide composite membrane is impregnated in the modification liquid formed in step (1) for 10-30 s, and dried after impregnation.

[0006] Preferably, the particle size of the porous silver particles is 20-200 nm.

[0007] Preferably, the first aqueous monomer is selected from one of aliphatic diamines, with a concentration of 0.05-0.1 wt%, and the first oil-phase monomer is selected from one of phthaloyl chloride compounds, with a concentration of 0.1-0.5 wt%.

[0008] Preferably, the concentration of polyamide-coated porous silver particles in the modification liquid in step (1) is 1-10 wt%.

[0009] Preferably, the support is one of microfiltration or ultrafiltration membranes.

[0010] Preferably, the second aqueous monomer is selected from one of aromatic diamines, with a concentration of 0.05-1 wt%, and the contact time between the support and it is 60-180 s; the second oil-phase monomer is trimesoyl chloride, with a concentration of 0.5-5 wt%, and the contact time between the support and it is 20-60 s.

[0011] Preferably, the drying time in step (2) is 1-4 h.

[0012] Preferably, the solvent in the polyamide solution in step (3) is one of ether, chloroform, N-methylpyrrolidone, dimethylformamide, and dimethylacetamide. The polyamide solution is a saturated solution of polyamide, and the weight-average molecular weight of the polyamide is 10,000-30,000.

[0013] Preferably, the impregnation time of the polyamide composite membrane in the modification liquid in step (3) is 10-60 s.

[0014] The silver-loaded antibacterial polyamide composite membrane prepared according to the above method comprises polyamide-coated porous silver particles loaded on the surface of the polyamide membrane.

[0015] Compared with the prior art, the present invention has the following advantages: First, the silver particles of the present invention are wrapped with polyamide and then coated on the surface of the polyamide composite membrane. The amino group of the polyamide shell forms an amide bond with the acyl chloride on the surface of the polyamide composite membrane, thereby improving the stability of the anti-pollution composite membrane without substantially reducing the anti-pollution ability of the silver particles.

[0016] Secondly, the present invention uses porous silver as the antibacterial particles. The porous property of the porous silver ensures that it can be wrapped with polyamide by interfacial polymerization, and the method of first oil phase and then water phase can increase the number of amino groups on the surface of the polyamide shell.

[0017] In addition, the coating of the polyamide polymer can improve the flatness of the surface layer of the polyamide composite membrane, avoid the accumulation of excessive antibacterial particles in local areas, increase the possibility of the silver particles being washed away, and the improved flatness of the polyamide membrane surface increases the anti-pollution ability of the composite membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 SEM image of the surface of the polyamide composite membrane prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with specific embodiments, so that those skilled in the art can fully understand the technical content of the present invention. It should be noted that the specific embodiments described herein are only used to explain the concept of the present invention and are not used to limit the present invention. For those not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0020] Example 1

[0021] The porous silver particles with an average particle size of 88 nm are first immersed in a n-hexane solution of isophthaloyl chloride with a concentration of 0.2 wt% for 5 minutes, then filtered and continuously immersed in an ethylenediamine solution with a concentration of 0.05 wt% for another 2 minutes. After filtration and drying at 60 °C for 6 hours, they are soaked in an aqueous solution and continuously stirred to form a 5 wt% modification solution for standby. A polysulfone ultrafiltration membrane is selected as the support. The surface of the support is first immersed in a 0.05 wt% m-phenylenediamine solution for 180 s. After removing the surface liquid, it is continuously immersed in a 2 wt% trimesoyl chloride cyclohexane solution for 30 s to form a polyamide composite membrane, which is then dried at 80 °C. Finally, the polyamide with a weight average molecular weight of 20,000 is dissolved in N-methylpyrrolidone to form a saturated solution. The saturated solution is evenly spin-coated on the polyamide composite membrane and heat-treated at 60 °C for 1 hour. Then, the polyamide composite membrane is immersed in the modification solution for 30 s, and after the immersion is completed, it is dried (the SEM characterization image is as Figure 1 shown).

[0022] Comparative Example 1 Soak porous silver particles with an average particle size of 88 nm in an aqueous solution and continuously stir to form a 5 wt% modification solution for standby; select a polysulfone ultrafiltration membrane as the support, and successively immerse the surface of the support in a 0.05 wt% m-phenylenediamine solution for 180 s. After removing the surface liquid, continue to immerse it in a 2 wt% cyclohexane solution of trimellitic acid chloride for 30 s to form a polyamide composite membrane, and dry it at 80 °C; finally, dissolve polyamide with a weight average molecular weight of 20,000 in N-methylpyrrolidone to form a saturated solution, uniformly scrape the saturated solution on the polyamide composite membrane, and heat-treat it at 60 °C for 1 h. Then immerse the polyamide composite membrane in the modification solution for 30 s, and dry it after the immersion ends.

[0023] Comparative Example 2 First, immerse solid silver particles with an average particle size of 42 nm in a 0.2 wt% n-hexane solution of isophthaloyl chloride for 5 min, then filter and continue to immerse it in a 0.05 wt% ethylenediamine solution for 2 min. After filtration and drying at 60 °C for 6 h, soak it in an aqueous solution and continuously stir to form a 5 wt% modification solution for standby; select a polysulfone ultrafiltration membrane as the support, and successively immerse the surface of the support in a 0.05 wt% m-phenylenediamine solution for 180 s. After removing the surface liquid, continue to immerse it in a 2 wt% cyclohexane solution of trimellitic acid chloride for 30 s to form a polyamide composite membrane, and dry it at 80 °C; finally, dissolve polyamide with a weight average molecular weight of 20,000 in N-methylpyrrolidone to form a saturated solution, uniformly scrape the saturated solution on the polyamide composite membrane, and heat-treat it at 60 °C for 1 h. Then immerse the polyamide composite membrane in the modification solution for 30 s, and dry it after the immersion ends.

[0024] Comparative Example 3 First, immerse porous silver particles with an average particle size of 58 nm in a 0.2 wt% n-hexane solution of isophthaloyl chloride for 5 min, then filter and continue to immerse it in a 0.05 wt% ethylenediamine solution for 2 min. After filtration and drying at 60 °C for 6 h, soak it in an aqueous solution and continuously stir to form a 5 wt% modification solution for standby; select a polysulfone ultrafiltration membrane as the support, and successively immerse the surface of the support in a 0.05 wt% m-phenylenediamine solution for 180 s. After removing the surface liquid, continue to immerse it in a 2 wt% cyclohexane solution of trimellitic acid chloride for 30 s to form a polyamide composite membrane, and dry it at 80 °C; finally, immerse the polyamide composite membrane in the modification solution for 30 s, and dry it after the immersion ends.

[0025] First, antibacterial performance test: Cut the above samples into 2-cm circular pieces, wash them with water, dry them, and sterilize them with ultraviolet light. Select Gram-negative Escherichia coli as the strain, and evaluate the antibacterial performance of different sample membranes through the plate counting method and the inhibition zone experiment. Secondly, test the separation performance: The test conditions are a sodium chloride solution of 1400 ppm, with a pH of 7.5. Measure the permeation performance of the membrane after it has been operating stably for 1 h at a temperature of 20°C and a test pressure of 150 psi; Finally, flush the sample membrane for 10 days under the condition of 250 Psi, and continue to take samples to test the antibacterial performance and separation performance of the membrane. The specific characterization data are shown in Table 1

[0026] Based on the above data, it can be seen that the silver-loaded antibacterial performance of the polyamide composite membrane prepared by the present invention is good and the stability is relatively good.

[0027] Of course, the present invention may also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention. However, these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. A preparation method of a silver-loaded antibacterial polyamide composite membrane, characterized in that It includes the following steps: Prepare polyamide-coated porous silver particles Successively immerse the porous silver particles in the first oil-phase monomer solution and the first water-phase monomer solution to form porous polyamide-coated porous silver particles on the outer layer of the porous silver. After filtration and drying, soak them in an aqueous solution and continuously stir to form a modified solution for standby; Prepare a polyamide composite membrane Successively immerse the second water-phase monomer solution and the second oil-phase monomer solution on the surface of the support to form a polyamide composite membrane by interfacial polymerization on the surface of the support, and dry it at 60-80 °C; Modify the polyamide composite membrane Uniformly scrape the dissolved polyamide solution on the polyamide composite membrane, and perform heat treatment at 40-60 °C for 0.5-1 h. Then immerse the polyamide composite membrane in the modified solution formed in step (1) for 10-30 s, and dry it after the immersion ends.

2. The preparation method according to claim 1, characterized in that The particle size of the porous silver particles is 20-200 nm.

3. The preparation method according to claim 1, characterized in that The first water-phase monomer is selected from one of aliphatic diamines, with a concentration of 0.05-0.1 wt%, and the first oil-phase monomer is selected from one of phthaloyl chloride compounds, with a concentration of 0.1-0.5 wt%.

4. The preparation method according to claim 1, characterized in that In step (1), the concentration of polyamide-coated porous silver particles in the modified solution is 1-10 wt%.

5. The preparation method according to claim 1, characterized in that The support is one of microfiltration or ultrafiltration membranes.

6. The preparation method according to claim 1, characterized in that The second water-phase monomer is selected from one of aromatic diamines, with a concentration of 0.05-1 wt%, and the contact time between the support and it is 60-180 s; the second oil-phase monomer is trimesoyl chloride, with a concentration of 0.5-5 wt%, and the contact time between the support and it is 20-60 s.

7. The preparation method according to claim 1, characterized in that The drying time in step (2) is 1-4 h.

8. The preparation method according to claim 1, characterized in that In step (3), the solvent in the polyamide solution is one of ether, chloroform, N-methylpyrrolidone, dimethylformamide, and dimethylacetamide. The polyamide solution is a saturated solution of polyamide, and the weight-average molecular weight of the polyamide is 10,000-30,000.

9. The preparation method according to claim 1, characterized in that In step (3), the immersion time of the polyamide composite membrane in the modified solution is 10-60 s.

10. A silver-loaded antibacterial polyamide composite membrane prepared according to claim 1, characterized in that The antibacterial polyamide composite membrane includes polyamide-coated porous silver particles loaded on the surface of the polyamide membrane.

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