Method for preparing silver-loaded antibacterial polyamide composite membrane

Abstract

The present invention relates to a method for preparing a membrane material, and more specifically, to a method for preparing a silver-loaded antibacterial polyamide composite membrane. The method involves modifying the exterior of porous silver particles with polyamide, which is then coated onto the outer surface of the polyamide composite membrane. The amino groups in the polyamide shell form amide bonds with the acyl chloride on the surface of the polyamide composite membrane, thereby improving the stability of the anti-fouling composite membrane without substantially reducing the anti-fouling ability of the silver particles.

Description

Technical Field

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

[0002] With the rapid development of industrialization and urbanization, water pollution and deteriorating water quality are becoming increasingly serious. Traditional water treatment methods often fail to meet the demand for high-quality water resources. Membrane separation technologies, such as reverse osmosis and nanofiltration, are highly effective and widely used in water treatment. However, traditional reverse osmosis membranes are susceptible to contamination by bacteria and microorganisms, resulting in reduced membrane permeability and separation efficiency, and may even cause secondary contamination.

[0003] In order to solve this problem, antibacterial polyamide composite reverse osmosis membranes came into being. By introducing antibacterial agents, such as nanosilver particles, and compounding them with polyamide membranes, the reverse osmosis membrane is given antibacterial properties. This composite membrane 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 permeability and service life of the membrane. In the prior art, the introduction of silver particles into polyamide composite membranes usually involves loading the silver particles on the membrane surface, but there are problems with the stability of the silver particle loading. There are also prior arts that directly introduce silver particles or place silver particles in an organic shell structure and blend them in the middle of a polyamide composite membrane, but the antibacterial and anti-pollution capabilities of the silver particles inside the membrane are reduced, and there are compatibility issues between the organic shell and the polyamide composite membrane, which affects the membrane quality. Therefore, how to solve the above problems has not been a good solution 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. The method comprises the following steps: modifying the exterior of porous silver particles with polyamide and then coating the particles on the outer surface of the polyamide composite membrane. The amino groups of the polyamide shell form amide bonds with the acyl chloride on the surface of the polyamide composite membrane, thereby improving the stability of the anti-fouling composite membrane without substantially reducing the anti-fouling ability of the silver particles.

[0005] Specifically, the present invention provides a method for preparing a silver-loaded antibacterial polyamide composite membrane, which is characterized by comprising the following steps:

[0006] Preparation of polyamide-coated porous silver particles

[0007] The porous silver particles are sequentially immersed 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, filtered, dried, and then immersed in an aqueous solution with continuous stirring to form a modification solution for use;

[0008] Preparation of polyamide composite membrane

[0009] The second aqueous phase monomer solution and the second oil phase monomer solution are successively impregnated on the surface of the support so as to form a polyamide composite membrane by interfacial polymerization on the surface of the support, and then dried at 60-80°C;

[0010] Modified polyamide composite membrane

[0011] The dissolved polyamide solution is evenly scraped onto the polyamide composite membrane and heat-treated at 40-60°C for 0.5-1h. The polyamide composite membrane is then immersed in the modification solution formed in step (1) for 10-30s and dried after the immersion.

[0012] Preferably, the particle size of the porous silver particles is 20-200 nm.

[0013] Preferably, the first aqueous 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 %.

[0014] Preferably, the concentration of the polyamide-coated porous silver particles in the modification solution in step (1) is 1-10 wt %.

[0015] Preferably, the support is a microfiltration or ultrafiltration membrane.

[0016] Preferably, the second aqueous phase monomer is selected from one of the aromatic diamines, with a concentration of 0.05-1 wt%, and the support is in contact with it for 60-180 s; the second oil phase monomer is trimesoyl chloride, with a concentration of 0.5-5 wt%, and the support is in contact with it for 20-60 s.

[0017] Preferably, the drying time in step (2) is 1 to 4 hours.

[0018] 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.

[0019] Preferably, in step (3), the immersion time of the polyamide composite membrane in the modification solution is 10 to 60 seconds.

[0020] The silver-loaded antibacterial polyamide composite membrane prepared according to the above method comprises porous silver particles coated with polyamide loaded on the surface of the polyamide membrane.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] First, the present invention wraps silver particles with polyamide and then coats them on the surface of a polyamide composite membrane. The amino groups of the polyamide shell form amide bonds with the acyl chloride on the surface of the polyamide composite membrane, thereby improving the stability of the anti-fouling composite membrane without substantially reducing the anti-fouling ability of the silver particles.

[0023] Secondly, the present invention uses porous silver as antibacterial particles. The porous properties of porous silver ensure that it can be encapsulated with polyamide by interfacial polymerization, and the oil phase first and then water phase method can increase the number of amino groups on the surface of the polyamide shell.

[0024] In addition, the coating of polyamide polymer can improve the smoothness of the surface of the polyamide composite membrane, avoid the accumulation of excessive antibacterial particles in local areas and increase the possibility of silver particles being washed away. The improved surface smoothness of the polyamide membrane also increases the anti-pollution ability of the composite membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 SEM image of the surface of the polyamide composite membrane prepared in Example 1. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific examples so that those skilled in the art can fully understand the technical contents of the present invention. It should be noted that the specific examples described herein are only used to explain the concept of the present invention and are not intended to limit the present invention. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0027] Example 1

[0028] The porous silver particles with an average particle size of 88 nm were first immersed in a 0.2wt% isophthaloyl chloride n-hexane solution for 5 minutes, then filtered and continued to be immersed in a 0.05wt% ethylenediamine solution for 2 minutes, filtered, dried at 60°C for 6 hours, and then immersed in an aqueous solution and continuously stirred to form a 5wt% modification solution for standby use; a polysulfone ultrafiltration membrane was selected as a support, and the surface of the support was immersed in a 0.05wt% m-phenylenediamine solution for 180 seconds, and after removing the surface liquid, it was continued to be immersed in a 2wt% cyclohexane solution of trimesoyl chloride for 30 seconds to form a polyamide composite membrane, and dried at 80°C; finally, a polyamide with a weight average molecular weight of 20,000 was dissolved in N-methylpyrrolidone to form a saturated solution, the saturated solution was evenly scraped on the polyamide composite membrane, and heat-treated at 60°C for 1 hour, and then the polyamide composite membrane was immersed in the modification solution for 30 seconds, and dried after the immersion (its SEM characterization figure is as shown in FIG. Figure 1 shown).

[0029] Comparative Example 1

[0030] Porous silver particles with an average particle size of 88 nm are immersed in an aqueous solution and continuously stirred to form a 5 wt% modification solution for use; a polysulfone ultrafiltration membrane is selected as a support, and the surface of the support is immersed in a 0.05 wt% m-phenylenediamine solution for 180 seconds. After removing the surface liquid, it is continuously immersed in a 2 wt% cyclohexane solution of trimesoyl chloride for 30 seconds to form a polyamide composite membrane, and then dried at 80°C; finally, a 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 scraped onto the polyamide composite membrane, and heat-treated at 60°C for 1 hour, and then the polyamide composite membrane is immersed in the modification solution for 30 seconds and dried after the immersion is completed.

[0031] Comparative Example 2

[0032] Solid silver particles with an average particle size of 42 nm were first immersed in a 0.2 wt% isophthaloyl chloride n-hexane solution for 5 minutes, then filtered and continued to be immersed in a 0.05 wt% ethylenediamine solution for 2 minutes, filtered, dried at 60 ° C for 6 hours, and then immersed in an aqueous solution and continuously stirred to form a 5 wt% modification solution for standby use; a polysulfone ultrafiltration membrane was selected as a support, and the surface of the support was immersed in a 0.05 wt% m-phenylenediamine solution for 180 seconds. After removing the surface liquid, it was continued to be immersed in a 2 wt% cyclohexane solution of trimesoyl chloride for 30 seconds to form a polyamide composite membrane, and then dried at 80 ° C; finally, a polyamide with a weight average molecular weight of 20,000 was dissolved in N-methylpyrrolidone to form a saturated solution, the saturated solution was evenly coated on the polyamide composite membrane, and heat treated at 60 ° C for 1 hour, and then the polyamide composite membrane was immersed in the modification solution for 30 seconds, and dried after the immersion.

[0033] Comparative Example 3

[0034] The porous silver particles with an average particle size of 58 nm were first immersed in a 0.2wt% isophthaloyl chloride n-hexane solution for 5 minutes, then filtered and continued to be immersed in a 0.05wt% ethylenediamine solution for 2 minutes, filtered, dried at 60°C for 6 hours, and then immersed in an aqueous solution with continuous stirring to form a 5wt% modification solution for standby use; a polysulfone ultrafiltration membrane was selected as a support, and the surface of the support was immersed in a 0.05wt% m-phenylenediamine solution for 180 seconds. After removing the surface liquid, it was continuously immersed in a 2wt% cyclohexane solution of trimesoyl chloride for 30 seconds to form a polyamide composite membrane, and then dried at 80°C; finally, the polyamide composite membrane was immersed in the modification solution for 30 seconds and dried after the immersion.

[0035] First, the bactericidal performance test: the above samples were cut into 2cm discs, washed with water, dried, and sterilized with ultraviolet light. Gram-negative Escherichia coli was selected as the bacterial species, and the antibacterial properties of different sample membranes were evaluated by plate counting method and inhibition zone experiment. Secondly, the separation performance was tested: the test conditions were 1400ppm sodium chloride solution, pH 7.5, and the permeability of the membrane was measured after 1h of stable operation at a temperature of 20°C and a test pressure of 150psi; finally, the sample membrane was flushed at 250Psi for 10d, and samples were taken to test the bactericidal and separation performance of the membrane. The specific characterization data are shown in Table 1

[0036]

[0037] Based on the above data, it can be seen that the polyamide composite film prepared by the present invention has good silver-loaded antibacterial performance and good stability.

[0038] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a silver-loaded antibacterial polyamide composite membrane, characterized in that The steps include: (1) Preparation of polyamide-coated porous silver particles The porous silver particles are sequentially immersed 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 particles. After filtering and drying, the porous silver particles are immersed in an aqueous solution with continuous stirring to form a modification solution for use. The first water phase monomer is selected from one of the aliphatic diamines at a concentration of 0.05-0.1 wt %, and the first oil phase monomer is selected from one of the phthaloyl chloride compounds at a concentration of 0.1-0.5 wt %. (2) Preparation of polyamide composite membrane The second aqueous phase monomer solution and the second oil phase monomer solution are successively impregnated on the surface of the support so as to form a polyamide composite membrane by interfacial polymerization on the surface of the support, and then dried at 60-80°C; (3) Modified polyamide composite membrane The dissolved polyamide solution is evenly scraped onto the polyamide composite film, and heat-treated at 40-60° C. for 0.5-1 h. The polyamide composite film is then immersed in the modification solution formed in step (1) for 10-30 s. After the immersion is completed, the film is dried. The polyamide solution is a saturated solution of polyamide, and the weight-average molecular weight of the polyamide is 10,000-30,000.

2. The preparation method according to claim 1, wherein The particle size of the porous silver particles is 20~200nm.

3. The preparation method according to claim 1, wherein The concentration of the polyamide-coated porous silver particles in the modification solution in step (1) is 1-10 wt %.

4. The preparation method according to claim 1, characterized in that The support is a microfiltration or ultrafiltration membrane.

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

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

7. The preparation method according to claim 1, characterized in that The solvent in the polyamide solution in step (3) is one of ether, chloroform, N-methylpyrrolidone, dimethylformamide and dimethylacetamide.

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

9. A silver-loaded antibacterial polyamide composite membrane prepared according to claim 1, characterized in that The antibacterial polyamide composite membrane comprises a polyamide membrane surface loaded with polyamide-coated porous silver particles.

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