Composite nanofiltration membrane and preparation method thereof
By grafting silver nanoparticles on the surface of the nanofiltration membrane amide bond, the problem of nanofiltration membrane being prone to biological contamination is solved, the antibacterial effect and separation performance are improved, and the stability and antibacterial effect of silver nanoparticles are achieved.
Patent Information
- Application Number
- CN202510197728.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-21
- Publication Date
- 2025-07-04
AI Technical Summary
The existing nanofiltration membranes are susceptible to biological contamination during use, resulting in a shortening of service life. The antibacterial nanofiltration membrane prepared by the traditional silver nitrate reduction method is prone to loss, and the antibacterial effect needs to be improved.
By grafting silver nanoparticles with amide bonds on the surface of the polyamide nanofiltration membrane layer to form a composite nanofiltration membrane, the silver nanoparticles have high stability in the functional layer and are not easily lost, improving the antibacterial effect.
The stability of silver nanoparticles in the functional layer is achieved, the antibacterial properties of the nanofiltration membrane are enhanced, biological pollution is reduced, and efficient separation performance is maintained.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of separation, and particularly relates to a composite nanofiltration membrane and a preparation method thereof. Background Art
[0002] Nanofiltration is a pressure-driven membrane separation process between ultrafiltration and reverse osmosis. The membrane pore size is in the nanometer range, and it has good removal effects on multivalent ions and organic substances with molecular weights between 200 and 1000. Nanofiltration membranes have been widely used in multiple fields such as water purification, wastewater treatment, and material separation. In the actual application process, membrane surface biofouling is a key factor restricting the service life of nanofiltration membranes. Therefore, developing antibacterial nanofiltration membranes will be one of the main directions for the future development of membrane technologies.
[0003] Currently, the methods for preparing antibacterial nanofiltration membranes include antibacterial nanofiltration membranes prepared by silver nitrate reduction method, but the antibacterial effect needs to be improved. Summary of the Invention
[0004] This application aims to solve at least one of the technical problems in the related technologies to some extent. For this reason, an object of the present invention is to provide a composite nanofiltration membrane and a preparation method thereof. In this composite nanofiltration membrane, silver nanoparticles are grafted onto the polyamide nanofiltration membrane through chemical bonds, with high stability and showing good antibacterial effects.
[0005] In one aspect of this application, a composite nanofiltration membrane is provided, including: a base membrane; and a functional layer located on at least one surface of the base membrane, the functional layer including polyamide and silver nanoparticles, and the silver nanoparticles being grafted onto the polyamide through amide bonds.
[0006] In the composite nanofiltration membrane provided by this application, the silver nanoparticles are grafted onto the polyamide through amide bonds, that is, the silver nanoparticles are introduced into the polyamide nanofiltration membrane through chemical bonds. The silver nanoparticles have high stability in the functional layer and are not easily lost during use, thereby facilitating the improvement of antibacterial effects and preventing biofouling of the nanofiltration functional layer.
[0007] In some embodiments, the base membrane includes at least one of polysulfone, polyethersulfone, and polyacrylonitrile.
[0008] In some embodiments, the base membrane includes at least one of polysulfone and polyethersulfone.
[0009] In the second aspect of this application, a preparation method of the above composite nanofiltration membrane is provided, including:
[0010] An initial-state nanofiltration membrane is provided. The initial-state nanofiltration membrane includes a base membrane and a polyamide nanofiltration membrane layer located on the surface of the base membrane; the polyamide in the polyamide nanofiltration membrane layer contains acyl chloride terminal functional groups; an aqueous solution of amino silver nanoparticles is placed on the surface of the polyamide nanofiltration membrane layer to jointly form a functional layer. The functional layer includes polyamide and silver nanoparticles, and the silver nanoparticles are grafted onto the polyamide through amide bonds.
[0011] In this application, the polyamide contains acyl chloride terminal functional groups. The acyl chloride terminal functional groups can be residues remaining during the synthesis of the polyamide or can be introduced through chemical modification after the synthesis of the polyamide. The acyl chloride terminal functional groups can be mono- or poly-acyl chloride functional groups.
[0012] In this application, by placing the aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer and reacting the acyl chloride terminal functional groups in the polyamide nanofiltration membrane layer with the amino groups in the amino silver nanoparticles, the silver nanoparticles are connected to the polyamide through amide bonds, realizing the chemical grafting of the silver nanoparticles onto the surface of the polyamide nanofiltration membrane layer. Therefore, the silver nanoparticles have high stability in the functional layer and are not easily lost during use, which is conducive to improving the antibacterial effect and preventing biological fouling of the nanofiltration functional layer.
[0013] In some embodiments, in the aqueous solution of amino silver nanoparticles, the concentration of the amino silver nanoparticles is 100 ppm to 1000 ppm.
[0014] In some embodiments, in the aqueous solution of amino silver nanoparticles, the average particle size of the amino silver nanoparticles is 10 nm to 50 nm.
[0015] In some embodiments, the step of placing the aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer to jointly form a functional layer takes 1 min to 10 min.
[0016] In some embodiments, providing the initial-state nanofiltration membrane includes preparing the initial-state nanofiltration membrane. Preparing the initial-state nanofiltration membrane includes: forming a polyamide nanofiltration membrane layer on the surface of the base membrane through an interfacial polymerization reaction with raw materials including a polyamine monomer and a polyacyl chloride monomer.
[0017] In some embodiments, preparing the initial-state nanofiltration membrane includes the steps of: coating an aqueous solution containing a polyamine monomer on the surface of the base membrane, and then coating an organic solution containing a polyacyl chloride monomer to obtain the initial-state nanofiltration membrane.
[0018] In some embodiments, preparing the initial-state nanofiltration membrane satisfies at least one of the following:
[0019] (ⅰ) The polyamine monomer includes at least one of piperazine, 2-carboxy piperazine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, diethylenetriamine, tetraethylenepentamine, and polyethyleneimine;
[0020] (ii) In the aqueous solution containing polyamine monomers, the concentration of the polyamine monomers is 0.5 w% to 5 w%;
[0021] (iii) The polyacyl chloride monomers include trimesoyl chloride;
[0022] (iii) In the organic solution containing polyacyl chloride monomers, the concentration of the polyacyl chloride monomers is 0.1 w% to 1 w%;
[0023] (iv) The organic solvent used in the organic solution containing polyacyl chloride monomers includes at least one of n - hexane, cyclohexane, ethylcyclohexane, and isoparaffin.
[0024] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Detailed Embodiments
[0025] The embodiments of the present invention will be described in detail below, which are intended to explain the present invention and should not be construed as limiting the present invention.
[0026] Currently, the method for preparing an antibacterial nanofiltration membrane is the antibacterial nanofiltration membrane prepared by the silver nitrate reduction method, but the antibacterial effect needs to be improved. For this antibacterial nanofiltration membrane prepared by the traditional silver nitrate reduction method, a silver nitrate solution is mixed with a reducing agent (such as hydrazine, ascorbic acid, or glucose), and silver ions are reduced under appropriate conditions to form silver nanoparticles. The reduced silver nanoparticles are dispersed in the nanofiltration membrane. Since the silver nanoparticles are introduced by a physical method, they are easily lost during use, affecting the use effect.
[0027] In the first aspect of the embodiments of the present application, a composite nanofiltration membrane is proposed, including: a base membrane; a functional layer located on at least one surface of the base membrane, the functional layer including polyamide and silver nanoparticles, and the silver nanoparticles are grafted onto the polyamide through amide bonds.
[0028] For the composite nanofiltration membrane provided in the embodiments of the present application, the silver nanoparticles are grafted onto the polyamide through amide bonds, that is, the silver nanoparticles are introduced into the polyamide nanofiltration membrane through chemical bonds. The silver nanoparticles have high stability in the functional layer and are not easily lost during use, thereby facilitating the improvement of the antibacterial effect and preventing the biological pollution of the nanofiltration functional layer.
[0029] In some embodiments of the present application, based on the functional layer, the mass percentage content of the silver nanoparticles is 0.1% to 1%. In specific examples, the mass percentage content of the silver nanoparticles is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.
[0030] When the mass percentage content of silver nanoparticles decreases, the antibacterial effect of the composite nanofiltration membrane shows a downward trend; when the mass percentage content of silver nanoparticles increases, it will affect the number of residual acyl chloride functional groups, and the surface charge of the membrane shows a downward trend, resulting in a downward trend in the rejection performance, and at the same time, it will also increase the production cost. When the mass percentage content of silver nanoparticles meets the above conditions, it is beneficial to obtain a higher antibacterial effect and a higher rejection performance.
[0031] In some embodiments of the present application, the base membrane includes at least one of polysulfone, polyethersulfone, and polyacrylonitrile.
[0032] In the embodiments of the present application, the base membrane can be used to provide a supporting role for the composite nanofiltration membrane. The base membrane provides a certain mechanical strength for the composite nanofiltration membrane, enabling the membrane to remain stable under high-pressure operating conditions. In addition to improving the mechanical properties of the composite nanofiltration membrane, the base membrane can also facilitate the improvement of the chemical resistance, filtration performance, and other properties of the composite nanofiltration membrane. The material of the base membrane can be selected from the base membrane materials well-known to those skilled in the art. In a specific example, the base membrane includes at least one of polysulfone, polyethersulfone, and polyacrylonitrile.
[0033] In some embodiments, the base membrane includes at least one of polysulfone and polyethersulfone.
[0034] The second aspect of the embodiments of the present application provides a method for preparing a composite nanofiltration membrane, including:
[0035] Providing an initial nanofiltration membrane, the initial nanofiltration membrane includes a base membrane and a polyamide nanofiltration membrane layer located on the surface of the base membrane; the polyamide in the polyamide nanofiltration membrane layer contains acyl chloride terminal functional groups;
[0036] Placing an aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer to jointly form a functional layer, the functional layer includes polyamide and silver nanoparticles, and the silver nanoparticles are grafted onto the polyamide through amide bonds.
[0037] In the embodiments of the present application, the polyamide contains acyl chloride terminal functional groups, which can be residues during the synthesis of the polyamide or introduced through chemical modification after the synthesis of the polyamide. The acyl chloride terminal functional groups can be mono- or poly-acyl chloride functional groups.
[0038] In the embodiments of the present application, by placing an aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer and reacting the acyl chloride terminal functional groups in the polyamide nanofiltration membrane layer with the amino groups in the amino silver nanoparticles, the silver nanoparticles are connected to the polyamide through amide bonds, realizing the chemical grafting of the silver nanoparticles onto the surface of the polyamide nanofiltration membrane layer. Therefore, the silver nanoparticles have high stability in the functional layer and are not easily lost during use, which is beneficial to improving the antibacterial effect and preventing biological pollution of the nanofiltration functional layer.
[0039] In some embodiments of the present application, in the aqueous solution of amino silver nanoparticles, the concentration of amino silver nanoparticles is 100 ppm to 1000 ppm. In specific examples, the concentration of amino silver nanoparticles is 100 ppm, 120 ppm, 140 ppm, 160 ppm, 180 ppm, 200 ppm, 220 ppm, 240 ppm, 260 ppm, 280 ppm, 300 ppm, 320 ppm, 340 ppm, 360 ppm, 380 ppm, 400 ppm, 420 ppm, 440 ppm, 460 ppm, 480 ppm, 500 ppm, 520 ppm, 540 ppm, 560 ppm, 580 ppm, 600 ppm, 620 ppm, 640 ppm, 660 ppm, 680 ppm, 700 ppm, 720 ppm, 740 ppm, 760 ppm, 780 ppm, 800 ppm, 820 ppm, 840 ppm, 860 ppm, 860 ppm, 880 ppm, 900 ppm, 920 ppm, 940 ppm, 960 ppm, 980 ppm, 1000 ppm, etc., or any other value between 100 ppm and 1000 ppm.
[0040] In the embodiments of the present application, the concentration of amino silver nanoparticles is 100 ppm to 1000 ppm, which is beneficial to the full reaction of the acyl chloride terminal functional groups of polyamide with amino groups, reaching or approaching a saturated state, enabling more silver nanoparticles to be grafted on the surface of the polyamide nanofiltration membrane and improving the antibacterial effect.
[0041] Furthermore, in the aqueous solution of amino silver nanoparticles, the concentration of amino silver nanoparticles is 400 ppm to 600 ppm.
[0042] When the concentration of amino silver nanoparticles in the aqueous solution of amino silver nanoparticles meets the above conditions, it is beneficial to improve the grafting efficiency and increase the antibacterial effect; in addition, it is beneficial to improve the retention performance of the composite nanofiltration membrane and reduce the production cost. This is because when the concentration of nano silver increases, the production cost tends to increase and the retention performance of the nanofiltration membrane tends to decline.
[0043] In some embodiments of the present application, in the aqueous solution of amino silver nanoparticles, the average particle size of the amino silver nanoparticles is 10 nm to 50 nm. In specific examples, the average particle size of the amino silver nanoparticles is 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm, etc., or any other value between 10 nm and 50 nm.
[0044] Further, in the aqueous solution of amino silver nanoparticles, the average particle size of the amino silver nanoparticles is 25 nm to 35 nm.
[0045] In the embodiments of the present application, the average particle size of the amino silver nanoparticles satisfies the above conditions, which is beneficial to improving the dispersibility of the amino silver nanoparticles in the aqueous solution, thereby improving the grafting effect.
[0046] In some embodiments of the present application, the step of placing the aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer to jointly form a functional layer takes 1 min to 10 min. In specific examples, the required time is 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.
[0047] In the embodiments of the present application, the step of placing the aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer to jointly form a functional layer takes 1 min to 10 min, that is, the grafting reaction time between the acyl chloride terminal functional group of the polyamide and the amino group of the amino silver nanoparticles is 1 min to 10 min, which is beneficial to the full reaction between the acyl chloride terminal functional group of the polyamide and the amino group to reach or approach a saturated state, so that more silver nanoparticles are grafted on the surface of the polyamide nanofiltration membrane, improving the antibacterial effect.
[0048] In some embodiments of the present application, providing an initial state nanofiltration membrane includes preparing an initial state nanofiltration membrane, and preparing the initial state nanofiltration membrane includes: forming a polyamide nanofiltration membrane layer on the surface of a base membrane through an interfacial polymerization reaction with raw materials including polyamine monomers and polyacyl chloride monomers.
[0049] Providing an initial state nanofiltration membrane may be directly using a sample of a polyamide nanofiltration membrane that already has an acyl chloride terminal functional group, or may be prepared by providing a method for preparing a polyamide nanofiltration membrane with an acyl chloride terminal functional group.
[0050] The preparation method of the composite nanofiltration membrane provided by the embodiments of the present application further includes the step of preparing an initial-state nanofiltration membrane. The polyamine monomer and the polyacyl chloride monomer form polyamide through an interfacial polymerization reaction, and steps such as post-heat treatment can be omitted, retaining the acyl chloride terminal functional groups remaining in the polyamide synthesis process, and enabling the remaining acyl chloride terminal functional groups to react with the amino groups in the amino silver nanoparticles for a secondary reaction to achieve chemical grafting of silver nanoparticles.
[0051] In some embodiments of the present application, preparing the initial-state nanofiltration membrane includes the steps of:
[0052] Coating an aqueous solution containing a polyamine monomer on the surface of the substrate membrane, and then coating an organic solution containing a polyacyl chloride monomer to obtain an initial-state nanofiltration membrane.
[0053] Dissolve the polyamine monomer (such as piperazine) in water to form an aqueous solution, and dissolve the polyacyl chloride monomer (such as trimesoyl chloride) in an organic solvent (such as n-hexane) to form an organic solution; coat the aqueous solution on the surface of the substrate membrane, and then cover it with the organic solution, and the two undergo an interfacial polymerization reaction on the surface of the substrate membrane to form a polyamide layer. A certain amount of acyl chloride terminal functional groups will remain in this polyamide layer for grafting reactions.
[0054] In some embodiments of the present application, preparing the initial-state nanofiltration membrane satisfies at least one of the following:
[0055] (ⅰ) The polyamine monomer includes at least one of piperazine, 2-carboxy piperazine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, diethylenetriamine, tetraethylenepentamine, and polyethyleneimine;
[0056] (ⅱ) In the aqueous solution containing the polyamine monomer, the concentration of the polyamine monomer is 0.5 w% to 5 w%;
[0057] (ⅲ) The polyacyl chloride monomer includes trimesoyl chloride;
[0058] (ⅲ) In the organic solution containing the polyacyl chloride monomer, the concentration of the polyacyl chloride monomer is 0.1 w% to 1 w%;
[0059] (ⅳ) The organic solvent used in the organic solution containing the polyacyl chloride monomer includes at least one of n-hexane, cyclohexane, ethylcyclohexane, and isoparaffin.
[0060] In the embodiments of the present application, the polyamine monomer can be selected from the polyamine monomer substances commonly used in the field for preparing polyamide nanofiltration membranes through interfacial polymerization. Specifically, for example, the polyamine monomer includes at least one of piperazine, 2-carboxy piperazine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, diethylenetriamine, tetraethylenepentamine, and polyethyleneimine.
[0061] In the embodiments of the present application, in the aqueous solution containing the polyamine monomer, the concentration of the polyamine monomer is 0.5 w% to 5 w%. This is conducive to promoting the effective progress of the interfacial polymerization reaction to form a dense polyamide nanofiltration membrane with appropriate pore size, which is beneficial to obtaining a nanofiltration membrane with high flux and magnesium sulfate rejection rate. The flux of the nanofiltration membrane is an important indicator to measure its water treatment ability, which represents the amount of water passing through a unit membrane area per unit time. The magnesium sulfate rejection rate of the nanofiltration membrane is an important indicator to measure its separation performance, which reflects the removal ability of the membrane for divalent salts such as magnesium sulfate. In specific examples, the concentration of the polyamine monomer is 0.5 w%, 0.6 w%, 0.7 w%, 0.8 w%, 0.9 w%, 1 w%, 1.1 w%, 1.2 w%, 1.3 w%, 1.4 w%, 1.5 w%, 1.6 w%, 1.7 w%, 1.8 w%, 1.9 w%, 2 w%, 2.1 w%, 2.2 w%, 2.3 w%, 2.4 w%, 2.5 w%, 2.6 w%, 2.7 w%, 2.8 w%, 2.9 w%, 3 w%, 3.1 w%, 3.2 w%, 3.3 w%, 3.4 w%, 3.5 w%, 3.6 w%, 3.7 w%, 3.8 w%, 3.9 w%, 4 w%, 4.1 w%, 4.2 w%, 4.3 w%, 4.4 w%, 4.5 w%, 4.6 w%, 4.7 w%, 4.8 w%, 4.9 w%, 5 w%, etc., or any other value between 0.5 w% and 5 w%.
[0062] In the embodiments of the present application, the polyacyl chloride monomer can be selected from the polyacyl chloride monomer substances commonly used in the field for preparing polyamide nanofiltration membranes by interfacial polymerization. In specific examples, the polyacyl chloride monomer includes one or more of trimellitic acid chloride, phthaloyl chloride, terephthaloyl chloride, and 1,3,6-naphthalenetrisulfonyl chloride.
[0063] In the embodiments of the present application, in the organic solution containing the polyacyl chloride monomer, the concentration of the polyacyl chloride monomer is 0.1 w% to 1 w%. This is conducive to promoting the effective progress of the interfacial polymerization reaction to form a dense polyamide nanofiltration membrane with appropriate pore size, which is beneficial to obtaining a nanofiltration membrane with high flux and magnesium sulfate rejection rate. At the same time, it is conducive to leaving a certain amount of acyl chloride terminal functional groups on the synthesized polyamide. In specific examples, the concentration of the polyacyl chloride monomer is 0.1 w%, 0.2 w%, 0.3 w%, 0.4 w%, 0.5 w%, 0.6 w%, 0.7 w%, 0.8 w%, 0.9 w%, 1 w%, etc., or any other value between 0.1 w% and 1 w%.
[0064] In some embodiments of the present application, the method for preparing the composite nanofiltration membrane includes the following steps:
[0065] S1000. Coating an aqueous solution containing a polyamine monomer on the surface of the substrate membrane;
[0066] S2000. Continuing to coat the organic solution containing polyfunctional acyl chloride monomers on the basis of step S1000 to obtain the initial-state nanofiltration membrane;
[0067] S3000. Coating an aqueous solution of amino silver nanoparticles on the surface of the initial-state nanofiltration membrane to prepare a composite nanofiltration membrane.
[0068] In the embodiments of the present application, an aqueous solution phase (aqueous solution containing polyamine monomers) is coated on the surface of the base membrane, and then covered with an organic solution phase (organic solution containing polyfunctional acyl chloride monomers). The two undergo an interfacial polymerization reaction on the surface of the base membrane to form a polyamide layer. Then, an aqueous solution of amino silver nanoparticles is continuously coated to carry out a grafting reaction to prepare a composite nanofiltration membrane.
[0069] During the water treatment process, the surface of the nanofiltration membrane is directly in contact with water and is prone to becoming a place for the attachment and reproduction of microorganisms. The attachment and reproduction of these microorganisms will lead to the formation of a biofilm, thereby affecting the separation performance and flux of the membrane, and increasing the difficulty and cost of cleaning and maintenance. Therefore, the surface of the nanofiltration membrane is required to have good antibacterial effects. The preparation method provided by the embodiments of the present application can graft a layer of silver nanoparticles on the surface of the polyamide nanofiltration membrane. The silver nanoparticles aggregate on the surface of the polyamide nanofiltration membrane, have a relatively high specific surface area, and exhibit good antibacterial effects.
[0070] The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way. The reagents used in the embodiments are all from Aladdin Biochemical Technology Co., Ltd.
[0071] Example 1
[0072] On the polysulfone base membrane, coat an aqueous solution phase containing 5 w% anhydrous piperazine and remove the excess water; then, coat an organic solution phase of isoparaffin (Isopar G) containing 1 w% trimesoyl chloride to obtain the initial-state nanofiltration membrane; finally, coat an aqueous solution of amino silver nanoparticles, wherein the size of the amino silver nanoparticles is 50 nm, the concentration of the amino silver nanoparticles is 1000 ppm, and the treatment time is 10 min to obtain the final composite nanofiltration membrane.
[0073] Example 2
[0074] On the polyethersulfone base membrane, coat an aqueous solution phase containing 0.5 w% anhydrous piperazine and remove the excess water; then, coat an organic solution phase of n-hexane containing 0.1 w% trimesoyl chloride to obtain the initial-state nanofiltration membrane; finally, coat an aqueous solution of amino silver nanoparticles, wherein the size of the amino silver nanoparticles is 10 nm, the concentration of the amino silver nanoparticles is 100 ppm, and the treatment time is 1 min to obtain the final composite nanofiltration membrane.
[0075] Example 3
[0076] On a polysulfone substrate membrane, a water-phase solution containing 2.5 w% anhydrous piperazine was coated, and the excess water was removed; then, a n-hexane organic-phase solution containing 0.5 w% trimesoyl chloride was coated to obtain an initial-state nanofiltration membrane; finally, an aqueous solution of amino silver nanoparticles with a size of 25 nm and a concentration of 500 ppm was coated for 5 min to obtain the final composite nanofiltration membrane.
[0077] Example 4
[0078] On a polyethersulfone substrate membrane, a water-phase solution containing 5 w% anhydrous piperazine was coated, and the excess water was removed; then, a n-hexane organic-phase solution containing 1 w% trimesoyl chloride was coated to obtain an initial-state nanofiltration membrane; finally, an aqueous solution of amino silver nanoparticles with a size of 10 nm and a concentration of 100 ppm was coated for 1 min to obtain the final composite nanofiltration membrane.
[0079] Example 5
[0080] The composite nanofiltration membrane was prepared by the method of Example 3, except that the size of the amino silver nanoparticles was 10 nm.
[0081] Example 6
[0082] The composite nanofiltration membrane was prepared by the method of Example 3, except that the size of the amino silver nanoparticles was 35 nm.
[0083] Example 7
[0084] The composite nanofiltration membrane was prepared by the method of Example 3, except that the size of the amino silver nanoparticles was 50 nm.
[0085] Example 8
[0086] The composite nanofiltration membrane was prepared by the method of Example 3, except that the concentration of the amino silver nanoparticles was 100 ppm.
[0087] Example 9
[0088] The composite nanofiltration membrane was prepared by the method of Example 3, except that the concentration of the amino silver nanoparticles was 800 ppm.
[0089] Example 10
[0090] The composite nanofiltration membrane was prepared by the method of Example 3, except that the concentration of the amino silver nanoparticles was 1000 ppm.
[0091] Example 11
[0092] The composite nanofiltration membrane was prepared by the method of Example 3, except that: polyethyleneimine was used to replace piperazine.
[0093] Example 12
[0094] The composite nanofiltration membrane was prepared by the method of Example 3, except that: terephthaloyl chloride was used to replace trimellitic anhydride chloride.
[0095] Comparative Example 1
[0096] On the polysulfone substrate membrane, a water-phase solution containing 2.5 w% anhydrous piperazine was coated, and the excess water was removed; then, a n-hexane organic-phase solution containing 0.5 w% trimellitic anhydride chloride was coated to obtain the initial-state nanofiltration membrane.
[0097] Comparative Example 2
[0098] The nascent nanofiltration membrane was prepared by the method of Example 1, and then the nascent nanofiltration membrane was immersed in an ethanol solution containing silver nitrate and photoinitiator benzophenone for 30 min, wherein the concentration of silver nitrate was 2000 ppm and the concentration of benzophenone was 2000 ppm, and then after ultraviolet irradiation at 365 nm for 1 h, the silver nanofiltration membrane was prepared.
[0099] The process parameters in Examples 1-12 and Comparative Examples 1-2 are shown in Table 1.
[0100] Table 1
[0101]
[0102] Performance Test
[0103] I. Test Method
[0104] 1. Pure water flux: It was measured by a commercial triple high-pressure flat membrane device and tested at 25 °C and 0.7 MPa.
[0105] 2. Magnesium sulfate rejection rate: It was measured by a commercial triple high-pressure flat membrane device and tested according to the regulations in GB / T 34242-2017, where the temperature was 25 °C, the pressure was 0.7 MPa, the concentration of magnesium sulfate was 2000 ppM, and the rejection rate was calculated by testing the conductivity. The rejection rate R = 1 - (C p / C f ) × 100%, where C p is the conductivity of the permeate and C f is the conductivity of the stock solution.
[0106] 3. Antibacterial performance test of the membrane sheet: Referring to the national standard "Test Method for Antibacterial Performance of Organic Separation Membranes" (GB / T 37206-2018), the selected strain was Escherichia coli.
[0107] II. Test Results
[0108] The performance test results of Examples 1-12 and Comparative Examples 1-2 are shown in Table 2 below.
[0109] Table 2
[0110] Serial number Retention rate of magnesium sulfate / % Water flux / LMH Antibacterial rate / % Example 1 98.7 41.2 99.3 Example 2 92.8 65.3 97.2 Example 3 95.4 55.9 95.1 Example 4 98.5 39.5 95.4 Example 5 97.2 46.2 94.5 Example 6 97.6 45.8 98.9 Example 7 95.6 51.3 95.2 Example 8 97.9 48.5 94.8 Example 9 97.5 45.6 93.8 Example 10 94.2 55.9 95.2 Example 11 98.2 41.9 98.5 Example 12 92.6 65.3 95.6 Comparative example 1 98.5 55.2 5.2 Comparative example 2 97.4 45.8 84.7
[0111] As shown by the test results in Table 2, the composite nanofiltration membranes provided in the embodiments of the present application exhibit good antibacterial effects, and the antibacterial rates of the composite nanofiltration membranes provided in each example are significantly higher than those of the comparative examples. In addition, the composite nanofiltration membranes provided in the embodiments of the present application can maintain a high water flux while effectively retaining the target substances.
[0112] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.
[0113] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.
Claims
1. A composite nanofiltration membrane, characterized in that, Comprising: Base film, A functional layer located on at least one side of the base film, the functional layer comprising polyamide and silver nanoparticles, the silver nanoparticles being grafted onto the polyamide via amide bonds.
2. The composite nanofiltration membrane according to claim 1, characterized in that, The base film comprises at least one of polysulfone, polyethersulfone, and polyacrylonitrile.
3. The composite nanofiltration membrane according to claim 1, wherein The base film comprises at least one of polysulfone and polyethersulfone.
4. The preparation method of the composite nanofiltration membrane according to any one of claims 1 to 3, characterized in that, Comprising: Providing an initial-state nanofiltration membrane, the initial-state nanofiltration membrane comprising a base film and a polyamide nanofiltration membrane layer located on the surface of the base film; the polyamide in the polyamide nanofiltration membrane layer contains acyl chloride terminal functional groups; Placing an aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer to jointly form a functional layer, the functional layer comprising polyamide and silver nanoparticles, the silver nanoparticles being grafted onto the polyamide via amide bonds.
5. The preparation method according to claim 4, characterized in that, In the aqueous solution of amino silver nanoparticles, the concentration of amino silver nanoparticles is 100 ppm to 1000 ppm.
6. The composite nanofiltration membrane according to claim 4, characterized in that, In the aqueous solution of amino silver nanoparticles, the average particle size of amino silver nanoparticles is 10 nm to 50 nm.
7. The preparation method according to claim 4, characterized in that, The step of placing the aqueous solution of amino silver nanoparticles on the surface of the polyamide nanofiltration membrane layer to jointly form a functional layer takes 1 min to 10 min.
8. The preparation method according to claim 5, wherein The providing of the initial-state nanofiltration membrane includes preparing the initial-state nanofiltration membrane, and the preparing of the initial-state nanofiltration membrane includes: Forming the polyamide nanofiltration membrane layer on the surface of the base film by interfacial polymerization reaction with raw materials including polyamine monomers and polyacyl chloride monomers.
9. The preparation method according to claim 8, wherein The preparing of the initial-state nanofiltration membrane includes the steps: Coating an aqueous solution containing the polyamine monomers on the surface of the base film, and then coating an organic solution containing the polyacyl chloride monomers to obtain the initial-state nanofiltration membrane.
10. The preparation method according to claim 9, wherein, The preparing of the initial-state nanofiltration membrane satisfies at least one of the following: (ⅰ) The polyamine monomers include at least one of piperazine, 2-carboxy piperazine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, diethylenetriamine, tetraethylenepentamine, and polyethyleneimine; (ⅱ) In the aqueous solution containing the polyamine monomers, the concentration of the polyamine monomers is 0.5 w% to 5 w%; (ⅲ) The polyacyl chloride monomers include trimesoyl chloride; (ⅲ) In the organic solution containing the polyacyl chloride monomers, the concentration of the polyacyl chloride monomers is 0.1 w% to 1 w%; (ⅳ) The organic solvents used in the organic solution containing the polyacyl chloride monomers include at least one of n-hexane, cyclohexane, ethylcyclohexane, and isoparaffin.