High-temperature-resistant antibacterial nanofiltration membrane and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant antibacterial nanofiltration membrane and a preparation method thereof.The preparation method of the high-temperature-resistant antibacterial nanofiltration membrane comprises the following steps that polyacrylonitrile powder is dissolved in a first organic solvent, and a polyacrylonitrile solution is obtained; adding an aminating agent into the polyacrylonitrile solution, and reacting for a period of time under a preset amination condition to obtain a uniform emulsion; collecting solid-phase components in the emulsion to obtain colloidal polymer particles; jointly dissolving the colloidal polymer particles and unmodified polyacrylonitrile powder in a second organic solvent in proportion to obtain a membrane casting solution; preparing the membrane casting solution on a non-woven fabric through a non-solvent induced phase separation method to obtain a composite base membrane; and immersing the composite base membrane in a water phase solution, coating the surface of the composite base membrane with an oil phase monomer solution, carrying out an interfacial polymerization reaction, and carrying out drying treatment to form a polyamide functional layer on the surface of the composite base membrane so as to obtain the target high-temperature-resistant antibacterial nanofiltration membrane.

Description

Technical Field

[0001] This invention relates to the field of nanofiltration membrane technology, and in particular to a high-temperature resistant and antibacterial nanofiltration membrane and its preparation method. Background Technology

[0002] Nanofiltration (NF) membranes, as a pressure-driven separation membrane between ultrafiltration and reverse osmosis, are widely used in water treatment, food processing, and chemical separation due to their excellent performance in divalent ion removal, organic matter separation, and water softening. Currently, composite nanofiltration membranes with polyamide (PA) as the selective layer are the mainstream products on the market, and they are usually prepared on a porous support layer by interfacial polymerization.

[0003] However, in practical applications, especially in high-temperature industrial wastewater treatment or high-temperature disinfection scenarios, traditional nanofiltration membranes face severe challenges. Existing technologies often use polyacrylonitrile (PAN) as the support layer material, but PAN-based membranes themselves suffer from insufficient heat resistance. As temperature rises, polymer chain segment movement intensifies, leading to a loosening of the support layer structure, increased pore size, and decreased mechanical strength. More critically, the polyamide selective layer and the PAN support layer are primarily bonded by physical forces (such as van der Waals forces and mechanical interlocking), lacking chemical bonding. Under high-temperature conditions, the two layers experience internal stress due to their different coefficients of thermal expansion, making them highly susceptible to delamination and blistering. This results in a sharp decline in membrane flux and a significant decrease in retention rate, severely limiting the application of nanofiltration technology under high-temperature conditions. Furthermore, in these applications, the presence of proteins and other substances in the wastewater makes the membranes prone to bacterial growth on the membrane surface during long-term operation.

[0004] Therefore, it is crucial to develop a nanofiltration membrane with excellent high-temperature resistance. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a high-temperature resistant and antibacterial nanofiltration membrane and its preparation method, which can improve the high-temperature resistance and antibacterial properties of the nanofiltration membrane.

[0006] To address the aforementioned technical problems, this invention provides a method for preparing a high-temperature resistant antibacterial nanofiltration membrane, comprising the following steps: dissolving polyacrylonitrile powder in a first organic solvent to obtain a polyacrylonitrile solution; adding an amination agent to the polyacrylonitrile solution and reacting under preset amination conditions for a period of time to obtain a uniform emulsion; collecting the solid phase component in the emulsion to obtain colloidal polymer particles; dissolving the colloidal polymer particles and unmodified polyacrylonitrile powder together in a second organic solvent in a certain proportion to obtain a casting solution; preparing a composite base membrane on a nonwoven fabric using a solvent-inducing phase separation method with the casting solution; immersing the composite base membrane in an aqueous solution, then coating the surface of the composite base membrane with an oil-phase monomer solution for interfacial polymerization, and after drying, forming a polyamide functional layer on the surface of the composite base membrane to obtain the target high-temperature resistant antibacterial nanofiltration membrane; wherein the aqueous solution comprises an aqueous monomer and an ionic liquid.

[0007] In one feasible implementation, the mass percentage of polyacrylonitrile in the polyacrylonitrile solution ranges from 15% to 18%.

[0008] In one feasible implementation, the molar ratio of polyacrylonitrile to the amination agent in the polyacrylonitrile solution is 6:1.

[0009] In one feasible implementation, the preset amination conditions include: an amination temperature range of 90°C, an amination gas atmosphere of nitrogen, and an amination time range of 3 to 6 hours.

[0010] In one feasible implementation, the mass ratio of colloidal polymer particles to unmodified polyacrylonitrile powder in the casting solution is 1:1.

[0011] In one feasible implementation, the steps of preparing the composite base membrane by the non-solvent-induced phase separation method include the following operations: the casting solution is scraped onto a nonwoven fabric to form a wet film with a thickness of 100-200 micrometers, and then the wet mill is immersed in a coagulation bath for phase transformation. After the film is completely solidified, the composite base membrane is obtained and stored in deionized water for later use.

[0012] In one feasible implementation, the aqueous monomer is selected from at least one of piperazine, m-phenylenediamine, p-phenylenediamine, 3,5-diaminobenzoic acid, ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexamethylenediamine, and 4-aminomethylpiperazine.

[0013] In one feasible implementation, the ionic liquid is selected from one of 1-ethyl-3-methylimidazolium lysine, 1-aminoethyl-3-methylimidazolium tetrafluoroborate, and 1-ethyl-3-methylimidazolium acetate.

[0014] In one feasible implementation, the oil phase monomer in the oil phase monomer solution is pyromellitic trimethylol chloride.

[0015] In one feasible implementation, the solvent of the oil phase monomer solution is selected from at least one of n-hexane or IsoparG.

[0016] In one feasible implementation, the interfacial polymerization reaction includes the following steps: immersing the composite base film in an aqueous solution containing 1wt%-10wt% aqueous monomer and 0.1wt%-1wt% ionic liquid for 1-5 minutes, then rolling off the excess aqueous phase; next, pouring it into an oil solution containing 0.1wt%-0.5wt% oil monomer, maintaining it for 1-3 minutes, then discarding the excess oil phase, and drying it in an oven.

[0017] In one feasible implementation, the first organic solvent is selected from at least one of N,N-dimethylacetamide, N,N-dimethylformamide (DMF), and N-methylpyrrolidone.

[0018] In one feasible implementation, the amination agent is selected from at least one of aromatic diamines or aliphatic diamines, wherein, In one feasible implementation, the aromatic diamine includes phenylenediamine; In one feasible implementation, the aliphatic diamine includes at least one of ethylenediamine, 1,6-diaminohexane, diethylenetriamine, propylenediamine, butanediamine, and m-phenylamine.

[0019] Accordingly, the present invention also provides a high-temperature resistant antibacterial nanofiltration membrane, which is prepared by any of the above-described methods for preparing high-temperature resistant antibacterial nanofiltration membranes.

[0020] Implementing this invention has the following beneficial effects: The method for preparing a high-temperature resistant antibacterial nanofiltration membrane provided in this application first modifies the polyacrylonitrile used to prepare the composite base membrane by amination. The composite base membrane prepared using amination-modified polyacrylonitrile not only has a more stable network structure due to the introduction of amino groups, but the introduced amino groups also react with acyl chlorides to form amide bonds, chemically anchoring the polyamide selective layer to the surface of the support layer, thus enhancing the overall high-temperature resistance of the high-temperature resistant antibacterial nanofiltration membrane. The ionic liquid introduced into the aqueous solution adds antibacterial ions to the formed polyamide layer, improving the overall antibacterial properties of the high-temperature resistant antibacterial nanofiltration membrane. Simultaneously, because the antibacterial ions are introduced during interfacial polymerization, the antibacterial properties are firmly fixed in the polyamide layer, thereby significantly improving the overall high-temperature resistance and antibacterial properties of the high-temperature resistant antibacterial nanofiltration membrane.

[0021] The high-temperature resistant antibacterial nanofiltration membrane of this application is prepared using the above-described method, comprising a composite base membrane prepared by amination-modified polyacrylonitrile, and a polyamide layer formed by interfacial polymerization on the basis of this composite base membrane. Due to the amino groups introduced by the amination modification, the composite base membrane has a more stable network structure. Simultaneously, the amino groups react with acyl chlorides to form amide bonds, chemically anchoring the polyamide functional layer to the surface of the composite base membrane, greatly enhancing the bonding force between the base membrane and the functional layer. The ionic liquid introduced into the aqueous solution adds antibacterial ions to the formed polyamide layer, improving the overall antibacterial properties of the high-temperature resistant antibacterial nanofiltration membrane. Furthermore, the introduction of antibacterial ions during the interfacial polymerization process ensures that the antibacterial properties are firmly fixed in the polyamide layer, thereby significantly improving the overall high-temperature resistance and antibacterial performance of the high-temperature resistant antibacterial nanofiltration membrane. Attached Figure Description

[0022] Figure 1 This is a flowchart of a method for preparing a high-temperature resistant antibacterial nanofiltration membrane according to an embodiment of this application. Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] Please see Figure 1 The method for preparing a high-temperature resistant antibacterial nanofiltration membrane according to an embodiment of the present invention includes the following steps: S110. Dissolve polyacrylonitrile powder in a first organic solvent to obtain a polyacrylonitrile solution.

[0026] In one feasible implementation, the operation of dissolving polyacrylonitrile (PAN) powder in an organic solvent is as follows: the polyacrylonitrile powder is added to the organic solvent and stirred at a temperature of 60°C to 90°C, at which point the polyacrylonitrile powder can be dissolved in the organic solvent relatively quickly.

[0027] In one feasible embodiment, the first organic solvent is selected from at least one of N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP). Optionally or preferably, the first organic solvent is a mixture of N,N-dimethylformamide (DMF) and N-methylpyrrolidone (NMP) in a mass ratio of 1:3.

[0028] In one feasible embodiment, the mass percentage of polyacrylonitrile in the polyacrylonitrile solution ranges from 15% to 18%. Further, the mass percentage of polyacrylonitrile in the polyacrylonitrile solution can be, but is not limited to, any value between 15%, 16%, 17%, 18%, or 15%-18%.

[0029] A suitable PAN concentration is crucial for ensuring the successful formation of a homogeneous emulsion and the subsequent acquisition of ideal colloidal particle morphology. Too low a concentration may result in excessively small particle size or low yield; too high a concentration will lead to excessively high solution viscosity, which is detrimental to the diffusion of the amination agent and the uniformity of the reaction, easily resulting in gelation or irregular aggregates. Optimizing this parameter range ensures that the amination reaction proceeds efficiently and controllably, laying the foundation for obtaining high-quality modified particles.

[0030] S120. An amination agent is added to the polyacrylonitrile solution, and after reacting for a period of time under preset amination conditions, a uniform emulsion is obtained.

[0031] In step S120, the cyano group of PAN undergoes a nucleophilic addition reaction with the primary amino group of the amination agent to generate an unstable intermediate—an amidine structure. Subsequently, under predetermined amination conditions (such as heating, acidic environment, or prolonged reaction), this amidine structure may further hydrolyze, transforming into a more stable amide group, or remain in the amidine form. Regardless of the final structure, the key is the successful introduction of additional amino or imino groups from the polyamine onto the PAN chain. Thus, after the amination reaction, the PAN polymer, originally containing only cyano groups, is transformed into one with a PAN backbone and side chains containing free amino or imino groups (i.e., grafted polyamine molecules). These introduced amino or imino groups can form additional hydrogen bonds or physical entanglements between PAN chains, constructing a denser, more cross-linked network structure. This network structure effectively inhibits the vigorous movement and relaxation of polymer chain segments at high temperatures, thereby improving the dimensional stability and mechanical strength of the base film in a high-temperature aqueous environment and solving the problem of base film structural instability caused by chain segment movement. More importantly, the surface of the composite film prepared by amination-modified polyacrylonitrile is rich in free amino groups. In the subsequent interfacial polymerization step, the oil-phase monomer not only reacts with piperazine in the aqueous phase to form a PA layer, but its active acyl chloride groups also react with the amino groups on the surface of the support layer to form strong amide bonds. In this way, the polyamide selective layer is chemically anchored or chemically bonded to the support layer through covalent bonds, rather than just being physically attached. This chemical connection greatly enhances the bonding force between the two layers. Even if both the PA layer and the support layer expand at high temperatures, delamination or peeling is not likely to occur, thus significantly improving the overall high-temperature resistance of the composite film.

[0032] In one feasible embodiment, the mass fraction ratio of polyacrylonitrile to amination agent in the polyacrylonitrile solution is in the range of 6:1.

[0033] In one feasible implementation, the amination agent in the polyacrylonitrile solution is in excess.

[0034] In one feasible implementation, the preset amination conditions include: an amination temperature range of 90°C, an amination gas atmosphere of nitrogen, and an amination time range of 4 hours. The high temperature (90°C) provides sufficient activation energy, accelerating the nucleophilic addition reaction rate between the cyano and amino groups and ensuring the reaction completes within a reasonable time. The nitrogen atmosphere isolates oxygen, preventing the amination agent or reaction intermediates from being oxidized and degraded at high temperatures, thus ensuring the purity and efficiency of the reaction. The optimized 4-hour reaction time is sufficient to achieve a high conversion rate while avoiding the risk of increased side reactions or polymer degradation due to excessively long reaction times.

[0035] In one feasible implementation, the homogeneous emulsion changes from yellow to orange or dark orange.

[0036] In one feasible implementation, the amination agent is selected from at least one of aromatic diamines or aliphatic diamines.

[0037] In one feasible implementation, the aromatic diamine includes phenylenediamine (PDA). The core advantage of using aromatic diamines (such as p-phenylenediamine and m-phenylenediamine) as amination agents lies in their excellent thermal stability and rigidity. The benzene ring structure possesses high bond energy and strong heat resistance. When grafted onto the PAN backbone, it acts like an embedded heat-resistant molecular pillar, significantly increasing the glass transition temperature and thermal decomposition temperature of the entire support layer. This fundamentally suppresses the violent movement of polymer chain segments at high temperatures, ensuring the support layer maintains structural stability in high-temperature environments. Furthermore, the rigid benzene ring can enhance the mechanical strength and modulus of the support layer and may promote the formation of a denser, more regular porous structure through intermolecular π-π stacking interactions, providing a more reliable physical basis for the composite membrane.

[0038] In one feasible implementation, the aliphatic diamine includes at least one selected from ethylenediamine (EDA), 1,6-diaminohexane (DAH), diethylenetriamine (DETA), propylenediamine, butanediamine, and m-phenylamine. The main advantages of using aliphatic diamines as amination agents are their high reactivity and molecular flexibility. The strong nucleophilicity of aliphatic primary amines allows for more efficient reaction with the cyano groups on the polyacrylonitrile (PAN) chain, achieving a higher amine grafting density. This introduces more active sites on the support layer surface that can be used for subsequent chemical anchoring, contributing to enhanced adhesion to the polyamide selective layer. Simultaneously, their long carbon chain structure increases the flexibility and toughness of the polymer network, making the support layer less brittle under heat or pressure, and potentially improving the hydrophilicity of the material, which is beneficial for improving the membrane's antifouling properties. Furthermore, these reagents are generally inexpensive.

[0039] Aromatic diamines or polyamines are selected as amination agents, as these molecules typically have higher thermal stability. When grafted onto PAN, they not only provide abundant amino groups for chemical anchoring, but their rigid structure also acts as molecular pillars, further inhibiting chain segment movement in the support layer at high temperatures and synergistically improving the heat resistance of the entire support layer.

[0040] S130. Collect the solid phase component in the emulsion to obtain colloidal polymer particles.

[0041] In one feasible implementation, the process of collecting the solid phase component of the emulsion includes centrifugation, washing, and drying. Further, the process of collecting the solid phase component of the emulsion may involve washing several times sequentially with DMF and an aqueous solution, followed by drying at 80°C to obtain colloidal polymer particles.

[0042] S140. The colloidal polymer particles and unmodified polyacrylonitrile powder are dissolved together in a second organic solvent in a certain proportion to obtain a casting solution.

[0043] In one feasible embodiment, the mass ratio of colloidal polymer particles to unmodified polyacrylonitrile powder in the casting solution is 1:1.

[0044] Increasing the proportion of modified particles can introduce more amino groups for chemical anchoring and further strengthen the support layer network. However, an excessively high proportion may affect the rheological properties and film-forming properties of the casting solution, leading to increased defects in the support layer. The original PAN powder provides the basic mechanical strength and film-forming framework. Optimizing this proportion can maximize its contribution to high-temperature resistance without affecting the basic properties of the support layer.

[0045] S150. The casting solution is used to prepare a composite base film on a nonwoven fabric by a non-solvent-induced phase separation method.

[0046] In one feasible embodiment, the steps of preparing the composite membrane by the non-solvent-induced phase separation method include the following operations: The casting solution is scraped onto a nonwoven fabric to form a wet film 100-200 micrometers thick. Then, the wet film is immersed in a coagulation bath for phase inversion. After the film is completely solidified, the composite base film is obtained and stored in deionized water for later use.

[0047] A suitable film thickness (100-200 micrometers) helps obtain a support layer with moderate mechanical strength and reasonable mass transfer resistance. Immersing the wet film in a coagulation bath is the core of achieving phase separation. Through rapid exchange between the solvent (DMF / NMP) and the non-solvent (water), the polymer is induced to precipitate from the solution, forming a composite base film with an asymmetric structure (dense skin layer and porous bottom layer). Storing it in deionized water prevents the collapse of the pore structure caused by drying, maintains its porosity and hydrophilicity, and creates favorable conditions for subsequent interfacial polymerization.

[0048] S160. The composite base membrane is first immersed in a mixed solution of aqueous monomer and ionic liquid, and then an oil-phase monomer solution is applied to the surface of the composite base membrane to carry out an interfacial polymerization reaction. After drying, a polyamide functional layer is formed on the surface of the composite base membrane to obtain the target high-temperature resistant and antibacterial nanofiltration membrane.

[0049] In one feasible embodiment, the aqueous monomer in the aqueous solution is selected from at least one of piperazine, m-phenylenediamine, p-phenylenediamine, 3,5-diaminobenzoic acid, ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexamethylenediamine, and 4-aminomethylpiperazine.

[0050] In one feasible embodiment, the ionic liquid is selected from one of 1-ethyl-3-methylimidazolium lysine, 1-aminoethyl-3-methylimidazolium tetrafluoroborate, and 1-ethyl-3-methylimidazolium acetate.

[0051] In one feasible embodiment, the oil phase monomer in the oil phase monomer solution is pyromellitic trimethylol chloride.

[0052] In one feasible embodiment, the solvent of the oil phase monomer solution is selected from at least one of n-hexane or IsoparG.

[0053] In one feasible embodiment, the steps of the interfacial polymerization reaction include the following operations: immersing the composite base film in a mixed solution containing 1wt%-10wt% aqueous monomer and 0.1wt%-1wt% ionic liquid for 1-5 minutes, then rolling off the excess aqueous phase; then pouring it into an oil phase solution containing 0.1wt%-0.5wt% oil phase monomer, maintaining it for 1-3 minutes, then discarding the excess oil phase, and drying it in an oven at 85°C.

[0054] Limiting the aqueous phase immersion time ensures a sufficient amount of aqueous monomers adsorbed on the support layer surface without excessive diffusion into the interior. Rolling off excess liquid controls the monomer loading. The oil phase reaction time (1-3 min) is sufficient to complete the interfacial polymerization reaction and form a dense PA layer; excessive time may lead to over-crosslinking and make the film brittle. The final 85°C drying is not only to remove solvent, but more importantly, to promote the post-crosslinking reaction of the PA layer, further improving its chemical stability and pressure resistance.

[0055] The method for preparing a high-temperature resistant antibacterial nanofiltration membrane provided in this application first involves amination modification of the polyacrylonitrile used to prepare the composite base membrane. The composite base membrane prepared using amination-modified polyacrylonitrile not only has a more stable network structure due to the introduction of amino groups, but the introduced amino groups also react with acyl chlorides to form amide bonds, chemically anchoring the polyamide selective layer to the surface of the support layer, thus enhancing the overall high-temperature resistance of the high-temperature resistant antibacterial nanofiltration membrane. The introduction of ionic liquids into the aqueous solution adds antibacterial ions to the formed polyamide layer, improving the overall antibacterial properties of the high-temperature resistant antibacterial nanofiltration membrane. Simultaneously, the introduction of antibacterial ions during interfacial polymerization ensures that the antibacterial properties are firmly fixed within the polyamide layer, thereby significantly improving the overall high-temperature resistance and antibacterial properties of the high-temperature resistant antibacterial nanofiltration membrane.

[0056] One embodiment of the high-temperature resistant antibacterial nanofiltration membrane is prepared using any of the above-described methods for preparing high-temperature resistant antibacterial nanofiltration membranes.

[0057] The high-temperature resistant antibacterial nanofiltration membrane of this application is prepared using the above-described method, comprising a composite base membrane prepared by amination-modified polyacrylonitrile, and a polyamide layer formed by interfacial polymerization on the basis of this composite base membrane. Due to the amino groups introduced by the amination modification, the composite base membrane has a more stable network structure. Simultaneously, the amino groups react with acyl chlorides to form amide bonds, chemically anchoring the polyamide functional layer to the surface of the composite base membrane, greatly enhancing the bonding force between the base membrane and the functional layer. The ionic liquid introduced into the aqueous solution adds antibacterial ions to the formed polyamide layer, improving the overall antibacterial properties of the high-temperature resistant antibacterial nanofiltration membrane. Furthermore, the introduction of antibacterial ions during the interfacial polymerization process ensures that the antibacterial properties are firmly fixed in the polyamide layer, thereby significantly improving the overall high-temperature resistance and antibacterial performance of the high-temperature resistant antibacterial nanofiltration membrane.

[0058] The high-temperature resistant and antibacterial nanofiltration membrane provided in this application exhibits thermal stability far exceeding that of traditional nanofiltration membranes due to its unique chemical anchoring structure. Even under long-term operation at temperatures above 80°C, it maintains stable flux and rejection rate, and is not prone to delamination or performance degradation. Membranes used in industrial processes requiring high-temperature wastewater reuse, heat-sensitive material concentration, and frequent high-temperature cleaning are particularly susceptible to bacterial growth on their surfaces during long-term operation due to the presence of proteins and other substances in the wastewater. The high-temperature resistant and antibacterial nanofiltration membrane provided in this application is especially suitable for industrial processes requiring high-temperature wastewater reuse, heat-sensitive material concentration, and frequent high-temperature cleaning.

[0059] Referring to the above implementation details, in order to make the technical solution of this application more specific, clear, and easy to understand, examples of the technical solution of this application are given below. However, it should be noted that the content to be protected by this application is not limited to the following embodiments.

[0060] Example 1 Dissolve 16g of PAN powder in a mixed solution of 46g of DMF and 138g of NMP; Stir and dissolve at 80°C. After the PAN is completely dissolved, slowly add 2.67g of ethylenediamine (EDA) solution and react for 4 hours under nitrogen protection at 90°C until the solution changes from pale yellow to orange and becomes a uniform emulsion. Then, the emulsion was centrifuged, washed several times with DMF and aqueous solution, and dried at 80°C to obtain colloidal polymer particles. Dissolve 6g of colloidal polymer particles and 6g of PAN powder in DMF until completely dissolved to obtain casting solution; A 150-micron thick wet film is scraped onto a nonwoven fabric, and then the wet film is immersed in a water coagulation bath. After the wet film is completely cured, a composite base film is obtained and stored in deionized water for later use. The composite base membrane was immersed in a mixed aqueous solution containing 0.7 wt% piperazine and 0.3% 1-ethyl-3-methylimidazolium lysine salt for 2 min, and then the excess aqueous phase was removed by rolling. Next, pour in a hexane solution containing 0.15 wt% TMC, keep for 1 minute, then discard the excess oil phase and dry in an oven at 85°C to obtain the target high-temperature resistant and antibacterial nanofiltration membrane.

[0061] Example 2 It is basically the same as Example 1, except that the amination agent is 1,6-hexanediamine (DAH).

[0062] Example 3 It is basically the same as Example 1, except that the amination agent is diethylenetriamine (DETA).

[0063] Example 4 It is basically the same as Example 1, except that the amination agent is p-phenylenediamine (PDA).

[0064] Example 5 It is basically the same as Example 3, except that the ionic liquid is 0.3% 1-aminoethyl-3-methylimidazolium tetrafluoroborate.

[0065] Example 6 It is basically the same as Example 3, except that the ionic liquid is 0.3% 1-ethyl-3-methylimidazolium acetate.

[0066] Comparative Example 1 Dissolve 16g of PAN powder in a mixed solution of 46g of DMF and 138g of NMP; Stir and dissolve at 80°C. After PAN is completely dissolved, slowly add 2.67g of diethylenetriamine (DETA) solution and react at 90°C under nitrogen protection for 4 hours until the solution changes from pale yellow to orange and becomes a uniform emulsion. Then, the emulsion was centrifuged, washed several times with DMF and aqueous solution, and dried at 80°C to obtain colloidal polymer particles. Dissolve 6g of colloidal polymer particles and 6g of PAN powder in DMF until completely dissolved to obtain casting solution; A 150-micron thick wet film is scraped onto a nonwoven fabric, and then the wet film is immersed in a water coagulation bath. After the wet film is completely cured, a composite base film is obtained and stored in deionized water for later use. The composite base membrane was immersed in an aqueous solution containing 0.7 wt% piperazine for 2 minutes, and then the excess aqueous phase was removed by rolling. Next, pour in a 0.15wt% TMC solution in n-hexane, maintain for 1 minute, then discard the excess oil phase. Dry in an oven at 85°C to obtain the nanofiltration membrane. Performance testing 1. The nanofiltration membranes prepared in the examples and comparative examples were tested with 2000ppm Na2SO4 solution, with feed temperatures of 25℃ and 80℃ respectively, and a test pressure of 15 bar. The tests were conducted after pre-pressurization for 20-30 minutes. The test results are shown in Tables 1 and 2.

[0067] 2. Escherichia coli was used as a representative bacterium to test the antibacterial properties of the nanofiltration membranes prepared in Examples 3, 5, 6 and Comparative Example 1. The test results are shown in Table 3.

[0068] Table 1. Results of flux and rejection rate at 25℃ Table 2. Results of flux and rejection rate at 80℃ Table 3 Antibacterial test results The test results above show that the high-temperature resistant antibacterial nanofiltration membrane prepared in this application embodiment can maintain stable flux and rejection rate even under long-term operation at high temperatures above 80°C, and is not prone to delamination or performance degradation. Specifically, when tested at 80°C, some embodiments showed increased flux but significantly reduced rejection rate, while the high-temperature resistant antibacterial nanofiltration membrane prepared in Example 3 showed increased flux and minimal reduction in rejection rate. This is because the amination agent selected in the preparation method provided in Example 3 is superior, and the synergistic effect of other preparation processes improves the overall performance of the high-temperature resistant antibacterial nanofiltration membrane.

[0069] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0070] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0071] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although some inventive embodiments that are currently considered useful have been discussed by way of various examples in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.

[0072] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0073] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0074] For each patent, patent application, patent application publication, and other material such as articles, books, specifications, publications, and documents referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0075] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A method for preparing a high-temperature resistant, antibacterial nanofiltration membrane, characterized in that, Includes the following steps: Polyacrylonitrile powder is dissolved in a first organic solvent to obtain a polyacrylonitrile solution; An amination agent is added to the polyacrylonitrile solution, and after reacting under preset amination conditions for a period of time, a uniform emulsion is obtained. The solid phase component in the emulsion is collected to obtain colloidal polymer particles; The colloidal polymer particles and unmodified polyacrylonitrile powder are dissolved together in a second organic solvent in a certain proportion to obtain a casting solution; A composite base film was prepared on a nonwoven fabric using the casting solution via a non-solvent-induced phase separation method. The composite base membrane is first immersed in an aqueous solution, and then an oil-phase monomer solution is applied to the surface of the composite base membrane to carry out an interfacial polymerization reaction. After drying, a polyamide functional layer is formed on the surface of the composite base membrane to obtain the target high-temperature resistant and antibacterial nanofiltration membrane. The aqueous solution includes an aqueous monomer and an ionic liquid.

2. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The mass percentage of polyacrylonitrile in the polyacrylonitrile solution ranges from 15% to 18%.

3. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The molar ratio of polyacrylonitrile to amination agent in the polyacrylonitrile solution is 6:

1.

4. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The preset amination conditions include: an amination temperature range of 90°C, an amination gas atmosphere of nitrogen, and an amination time range of 3 to 6 hours.

5. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The mass ratio of colloidal polymer particles to unmodified polyacrylonitrile powder in the casting solution is 1:

1.

6. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The steps for preparing the composite membrane using the solvent-inducible phase separation method include the following operations: The casting solution is scraped onto a nonwoven fabric to form a wet film with a thickness of 100-200 micrometers. Then, the wet film is immersed in a coagulation bath for phase transformation. After the film is completely solidified, the composite base film is obtained and stored in deionized water for later use.

7. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The aqueous phase monomer is selected from at least one of piperazine, m-phenylenediamine, p-phenylenediamine, 3,5-diaminobenzoic acid, ethylenediamine, propylenediamine, butylenediamine, pentanediamine, hexamethylenediamine, and 4-aminomethylpiperazine; The ionic liquid is selected from one of 1-ethyl-3-methylimidazolium lysine salt, 1-aminoethyl-3-methylimidazolium tetrafluoroborate, and 1-ethyl-3-methylimidazolium acetate; The oil phase monomer in the oil phase monomer solution is pyromellitic trimethylol chloride; The solvent for the oil phase monomer solution is selected from at least one of n-hexane or Isopar G.

8. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The steps of the interfacial polymerization reaction include the following operations: immersing the composite base film in an aqueous solution containing 1wt%-10wt% aqueous monomer and 0.1wt%-1wt% ionic liquid for 1-5 minutes, then rolling off the excess aqueous phase; then pouring it into an oil solution containing 0.1wt%-0.5wt% oil monomer, keeping it for 1-3 minutes, then discarding the excess oil phase, and drying it in an oven.

9. The method for preparing the high-temperature resistant antibacterial nanofiltration membrane according to claim 1, characterized in that, The first organic solvent is selected from at least one of N,N-dimethylacetamide, N,N-dimethylformamide (DMF), and N-methylpyrrolidone; The amination agent is selected from at least one of aromatic diamines or aliphatic diamines, wherein... The aromatic diamine includes phenylenediamine; The aliphatic diamine includes at least one of ethylenediamine, 1,6-diaminohexane, diethylenetriamine, propylenediamine, butanediamine, and m-aniline.

10. A high-temperature resistant and antibacterial nanofiltration membrane, characterized in that, The nanofiltration membrane was prepared using the method described in any one of claims 1-9.

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