High-flux antibacterial reverse osmosis membrane and preparation method thereof

Abstract

The invention discloses a high-flux antibacterial reverse osmosis membrane and a preparation method thereof. The reverse osmosis membrane comprises a base membrane and a polyamide desalination layer, the polyamide desalination layer is formed on the surface of the base membrane through an interfacial polymerization reaction of an acyl chloride monomer and an aromatic amine monomer, and a ZIF-8 nano material is embedded in the polyamide desalination layer. The preparation method comprises the following steps: S1, providing a base membrane, and soaking and storing the base membrane in water for later use; s2, dissolving chitosan quaternary ammonium salt, a ZIF-8 nano material and an aromatic amine monomer in water, and performing ultrasonic dispersion to obtain a water-phase liquid; s3, dissolving an acyl chloride monomer in an organic solvent to obtain an oil phase liquid; and S4, immersing a base membrane into the aqueous phase liquid for treatment, taking out the base membrane, removing the residual aqueous phase liquid on the surface of the base membrane, pouring the oil phase liquid onto the surface of the base membrane, carrying out interfacial polymerization reaction, removing the liquid on the surface of the membrane, and drying to prepare the positively charged polyamide reverse osmosis membrane embedded with the ZIF-8 nano material.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment separation membranes, and in particular to a high-flux antibacterial reverse osmosis membrane and a preparation method thereof. The reverse osmosis membrane is suitable for household water purification. Background Art

[0002] In the field of household water purification, reverse osmosis membranes are often contaminated by bacteria, which seriously affects the water purification effect and the service life of membrane elements. Studies have shown that bacterial contamination on the surface of reverse osmosis membranes is caused by a series of activities such as microorganisms adsorbing to the membrane surface, growing, proliferating, dying, precipitating, and polymerizing on the membrane surface. Bacterial contamination will reduce the dissolution-diffusion dynamics, resulting in poor membrane separation effect and a decrease in water production. In actual use, it will also cause a sharp decrease in the service life of the reverse osmosis membrane.

[0003] Therefore, in order to solve the problem of reduced performance and service life of reverse osmosis membranes in the field of household water purification due to their susceptibility to microbial contamination, the prior art adopts the following technical solutions: for example, Chinese patent CN201410443370 discloses that ZIF-8 material is embedded in the desalination layer as an additive, which can increase the fluid channel in the membrane and effectively improve the membrane flux. However, the agglomeration problem of the ZIF-8 material limits the concentration of addition, which leads to a decrease in the effective antibacterial ability; and in patent CN202210687721, carboxymethyl chitosan quaternary ammonium salt is used to form an antibacterial protective layer, and a cation-rich protective membrane is used to improve the antibacterial ability of the reverse osmosis membrane. However, the protective layer fixed on the surface of the reverse osmosis membrane by reacting with residual acyl chloride groups is at risk of being easily detached due to residual chlorine attack. Summary of the invention

[0004] The purpose of the present invention is to provide a high-flux antibacterial reverse osmosis membrane suitable for household water purification and a preparation method thereof, aiming to solve the problem that the existing reverse osmosis membrane is easily contaminated by bacteria, which affects its performance and service life. The reverse osmosis membrane of the present invention effectively improves the antibacterial performance and osmotic flux of the membrane, thereby avoiding the decline in the performance of the reverse osmosis membrane and the shortening of its service life.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions:

[0006] The invention provides a high-flux antibacterial reverse osmosis membrane, which comprises a base membrane and a polyamide desalination layer; wherein the polyamide desalination layer is formed on the surface of the base membrane by an interfacial polymerization reaction of an acyl chloride monomer and an aromatic amine monomer, and a ZIF-8 nanomaterial is embedded in the polyamide desalination layer.

[0007] Specifically, the base film of the present invention can be selected from one of polysulfone base film, polyethersulfone base film, polyvinylidene fluoride base film, polyethylene base film, polyacrylonitrile base film and polyetheretherketone base film.

[0008] Specifically, the present invention introduces metal organic frameworks (MOFs), particularly ZIF-8 nanoparticles into a polyamide desalination layer, and utilizes its sterilization mechanism and sustained-release principle to carry out antibacterial modification on the diaphragm, thereby making the reverse osmosis membrane possess a long-acting sterilization ability. At the same time, the present invention introduces chitosan quaternary ammonium salt into an aqueous phase solution, and the chitosan quaternary ammonium salt and the ZIF-8 nano material have good compatibility in a polymer. The chitosan quaternary ammonium salt, as a surfactant, can effectively solve the problem of uneven dispersion of ZIF-8 nano material in a polyamide desalination layer under a higher concentration and the hydrophobic surface problem brought by ZIF-8. The present invention is based on the synergistic effect of ZIF-8 nano material and chitosan quaternary ammonium salt, and finally obtains a kind of antibacterial reverse osmosis membrane with high flux.

[0009] The present invention also provides a method for preparing a high-flux antibacterial reverse osmosis membrane. The method comprises the following steps:

[0010] S1. Basement membrane preparation: provide a basement membrane and soak it in water for storage;

[0011] S2, preparing aqueous phase liquid: dissolving chitosan quaternary ammonium salt, ZIF-8 nanomaterials and aromatic amine monomers in water, and ultrasonically dispersing to obtain aqueous phase liquid;

[0012] S3, preparing the oil phase liquid: dissolving the acyl chloride in an organic solvent to obtain an oil phase liquid;

[0013] S4, preparation of reverse osmosis membrane: immerse the base membrane in the aqueous phase liquid for treatment, remove the residual aqueous phase liquid on the surface of the base membrane after taking it out, and then pour the oil phase liquid on the surface of the base membrane for interfacial polymerization reaction, remove the liquid on the membrane surface, dry it, and prepare a positively charged polyamide reverse osmosis membrane with ZIF-8 nanomaterials embedded inside.

[0014] Furthermore, a method for preparing a high-flux antibacterial reverse osmosis membrane is provided: the concentration of the chitosan quaternary ammonium salt in the aqueous phase is 0.5-5.0 wt %.

[0015] Furthermore, a method for preparing a high-flux antibacterial reverse osmosis membrane is provided: the chitosan quaternary ammonium salt is selected from hydroxypropyltrimethylammonium chloride chitosan, and the substitution degree of the chitosan quaternary ammonium salt is not less than 92.0%.

[0016] Furthermore, a method for preparing a high-flux antibacterial reverse osmosis membrane is provided: the concentration of the ZIF-8 nanomaterial in the aqueous phase is 0.2 to 2.0 wt %.

[0017] Furthermore, a method for preparing a high-flux antibacterial reverse osmosis membrane is provided: the particle size of the ZIF-8 nanomaterial is 50 to 500 nm.

[0018] Furthermore, a method for preparing a high-flux antibacterial reverse osmosis membrane is provided: the concentration of the aromatic amine monomer in the aqueous phase liquid is 1.0 to 5.0 wt %.

[0019] Preferably, the concentration of the aromatic amine monomer in the aqueous phase is 2.5 wt %.

[0020] Furthermore, a method for preparing a high-flux antibacterial reverse osmosis membrane is provided: the aromatic amine monomer is selected from any one of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine and benzidine.

[0021] Furthermore, a method for preparing a high-flux antibacterial reverse osmosis membrane is provided: the concentration of the acyl chloride monomer in the oil phase liquid is 0.02-0.3 wt%, and the acyl chloride is selected from one or more of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, and cyclohexanetrichloride; the organic solvent is selected from one or more of n-hexane, cyclohexane, n-heptane, and isoparaffin solvents.

[0022] Preferably, the acyl chloride monomer is trimesoyl chloride, and its concentration in the oil phase liquid is 0.05-0.3 wt %.

[0023] Furthermore, a method for preparing a high-throughput antibacterial reverse osmosis membrane is provided: the base membrane is first immersed in the aqueous phase liquid for 15 to 60 seconds, and after being taken out, the residual aqueous phase liquid on the front side of the base membrane is removed by air knife blowing, and the residual aqueous phase liquid on the back side of the base membrane is removed by wiping with absorbent paper, and then the oil phase liquid is poured on the surface of the base membrane (completely covering the surface of the base membrane) for interfacial polymerization for 20 to 60 seconds to form a polyamide desalination layer, the liquid on the membrane surface is removed, and then the membrane is dried at 60 to 80°C for 1 to 5 minutes, thereby preparing a positively charged polyamide reverse osmosis membrane with ZIF-8 nanomaterials embedded inside.

[0024] The high-flux antibacterial reverse osmosis membrane provided by the present invention contains the metal organic framework material ZIF-8 introduced by the blending technology in its polyamide desalination layer, and there is good compatibility between ZIF-8 and the polyamide desalination layer, and the hydrophobic channel formed by it can make the internal water molecules of the desalination layer pass quickly, and improve the reverse osmosis membrane flux. Meanwhile, the ZIF-8 nano material formed by the coordination of imidazole small molecules and zinc ions can also show good antibacterial properties, but its spontaneous agglomeration phenomenon and hydrophobicity can affect the performance of the reverse osmosis membrane. Therefore, the present invention also introduces hydroxypropyl trimethyl ammonium chloride chitosan (chitosan quaternary ammonium salt) in the aqueous phase liquid, and chitosan quaternary ammonium salt can effectively suppress the agglomeration of ZIF-8 nanoparticles as a surfactant, and the quaternary ammonium salt group can significantly improve the hydrophilicity of the membrane surface, improve membrane flux, and simultaneously utilize its cationic charge to hinder the growth and proliferation of membrane surface bacteria, and can also be used as an auxiliary antibacterial agent to improve the antibacterial property of the reverse osmosis membrane. The present invention can fully improve the antibacterial performance of the membrane surface through the synergistic effect of quaternary ammonium salt cations and ZIF-8 nanomaterials, and fully improve the permeation flux of the reverse osmosis membrane based on the internal water channels of the separation layer provided by the ZIF-8 nano additive and the hydrophilic membrane surface modified by the quaternary ammonium salt.

[0025] Beneficial effects of the present invention:

[0026] (1) The high-flux antibacterial reverse osmosis membrane provided by the present invention selects ZIF-8 nanomaterials with good compatibility and good antibacterial properties with the polyamide desalination layer as the aqueous phase liquid additive, successfully disperses and embeds a relatively high concentration of ZIF-8 nanomaterials in the polyamide desalination layer. The release kinetics of the ZIF-8 nanomaterials are characterized, and it is found that the ZIF-8 nanomaterials slowly degrade and release Zn during the reverse osmosis membrane water production process. 2+ , part of which Zn 2+ It affects the negatively charged cell membrane, causing the cytoplasm to flow out, thus killing bacteria. The other part of Zn 2+ It will pass through the bacterial cell membrane and accumulate inside the bacteria, causing the physiological function of the bacteria to be disrupted, hindering the proliferation of bacteria and accelerating the death of bacteria, thereby achieving an antibacterial effect. In addition, the imidazole substances slowly released by the ZIF-8 nanomaterial also have a high bactericidal efficiency. Therefore, the addition of the ZIF-8 nanomaterial additive effectively improves the antibacterial performance of the reverse osmosis membrane.

[0027] (2) The ZIF-8 nanomaterial used in the present invention as an additive can also modify the internal transmission channel of the polyamide desalination layer. The ZIF-8 nanoparticles embedded under the polyamide desalination layer have a hydrophobic surface that can accelerate the transmission efficiency of water molecules in the polyamide desalination layer. The new fluid channels constructed by the ZIF-8 nanoparticles inside the polyamide desalination layer can increase the transmission channels of water molecules in the membrane. Under the synergistic effect of the two, the permeation flux of the reverse osmosis membrane can be effectively improved.

[0028] (3) The present invention also adds chitosan quaternary ammonium salt to the aqueous phase liquid. As a surfactant, chitosan quaternary ammonium salt helps ZIF-8 nanoparticles to disperse better in solution by reducing surface tension. Specifically, chitosan quaternary ammonium salt forms a protective layer on the surface of ZIF-8 nanoparticles to prevent aggregation and precipitation between ZIF-8 nanoparticles. Based on the protection of chitosan quaternary ammonium salt, even when the concentration of ZIF-8 nanomaterial is added at a high level, the integrity of the polyamide desalination layer will not be destroyed due to self-agglomeration, thereby ensuring the separation performance of the reverse osmosis membrane. At the same time, the hydrophilic quaternary amine group and hydroxyl group brought into by chitosan quaternary ammonium salt can effectively improve the hydrophilicity of the membrane surface. The enhancement of the hydrophilicity of the membrane surface is conducive to reducing the mass transfer resistance of water molecules, thereby effectively improving the permeability of the membrane. The hydrophilic group can form a water-containing layer on the membrane surface by forming hydrogen bonds with water molecules, thereby weakening the enrichment of pollutants on the membrane surface. Chitosan quaternary ammonium salt can also be used as an auxiliary antibacterial material to improve the antibacterial ability of the reverse osmosis membrane surface.

[0029] (4) The high-flux antibacterial reverse osmosis membrane provided by the present invention has shown excellent permeation flux and excellent antibacterial properties in the field of household water purification, and the preparation process is simple, safe and environmentally friendly. The modified materials used are low-cost and have good commercial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a water contact angle diagram of the high-flux antibacterial reverse osmosis membrane prepared in Example 1;

[0032] Figure 2 This is a water contact angle diagram of the polyamide composite reverse osmosis membrane prepared in Comparative Example 1. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment 1 provides a high-flux antibacterial reverse osmosis membrane, which includes a base membrane and a polyamide desalination layer; the polyamide desalination layer is formed on the surface of the base membrane by interfacial polymerization of acyl chloride monomers and aromatic amine monomers, and ZIF-8 nanomaterials are embedded in the polyamide desalination layer.

[0036] The method for preparing the high-flux antibacterial reverse osmosis membrane comprises the following specific steps:

[0037] S1. Preparation of base membrane: provide commercial polysulfone base membrane and soak it in pure water before use;

[0038] S2, preparing an aqueous phase liquid: first, dissolving an aromatic amine in pure water to obtain an amine monomer solution, then adding a chitosan quaternary ammonium salt additive to the amine monomer solution, stirring and dissolving, and then adding a ZIF-8 nanomaterial to the system, and dispersing the ZIF-8 nanomaterial with the aid of ultrasound (ultrasound for 20 minutes), thereby obtaining a uniformly dispersed aqueous phase liquid;

[0039] The aromatic amine is m-phenylenediamine, and its concentration in the aqueous phase is 2.5wt%; the chitosan quaternary ammonium salt is hydroxypropyltrimethylammonium chloride chitosan with a substitution degree of not less than 92.0%, and its concentration in the aqueous phase is 1.0wt%; the particle size of the ZIF-8 nanomaterial is 50nm, and its concentration in the aqueous phase is 0.8wt%;

[0040] S3, preparation of oil phase liquid: dissolving trimesoyl chloride in n-hexane solvent to obtain an oil phase liquid with a concentration of 0.175 wt %;

[0041] S4. Preparation of reverse osmosis membrane: take out the polysulfone base membrane soaked in pure water in advance, immerse it in aqueous liquid and let it stand for 15 seconds, then use a wind knife to blow away the residual aqueous liquid on the front side of the base membrane, wipe it with absorbent paper to remove the residual aqueous liquid on the back side of the base membrane, and then pour the oil phase liquid on the surface of the base membrane (completely covering the surface of the base membrane) to carry out interfacial polymerization for 25 seconds to form a polyamide desalination layer, remove excess oil phase liquid on the membrane surface, and then put it in an oven at 60°C to dry for 2 minutes to obtain a positively charged polyamide reverse osmosis membrane with ZIF-8 nanomaterials embedded inside, which is a high-flux antibacterial reverse osmosis membrane.

[0042] Example 2

[0043] The difference between Example 2 and Example 1 is that the concentration of chitosan quaternary ammonium salt in the aqueous phase of Example 2 is 0.5wt%, the concentration of aromatic amine monomer is 1.5wt%, and the other conditions are the same as those of Example 1.

[0044] Example 3

[0045] The difference between Example 3 and Example 1 is that the concentration of the ZIF-8 nanomaterial in the aqueous phase liquid of Example 3 is 1.2 wt %, and the other conditions are the same as those of Example 1.

[0046] Example 4

[0047] The difference between Example 4 and Example 1 is that the concentration of ZIF-8 nanomaterial in the aqueous phase of Example 4 is 1.2 wt %, the concentration of chitosan quaternary ammonium salt is 1.5 wt %, and the other conditions are the same as those of Example 1.

[0048] Example 5

[0049] The difference between Example 5 and Example 1 is that the particle size of the ZIF-8 nanomaterial in the aqueous phase liquid of Example 5 is 500 nm, and the rest is the same as Example 1.

[0050] Example 6

[0051] The difference between Example 6 and Example 1 is that the concentration of the ZIF-8 nanomaterial in the aqueous phase of Example 6 is 0.2 wt %, and the rest is the same as Example 1.

[0052] Comparative Example 1

[0053] Provided is a method for preparing a polyamide composite reverse osmosis membrane, comprising the following specific steps:

[0054] (1) providing a commercial polysulfone-based membrane and soaking it in pure water before use;

[0055] (2) dissolving m-phenylenediamine in pure water to obtain an aqueous phase liquid A with a concentration of 2.5 wt %;

[0056] (3) dissolving trimesoyl chloride in n-hexane solvent to obtain an oil phase liquid B with a concentration of 0.175 wt %;

[0057] (4) The polysulfone base membrane soaked in pure water in advance is taken out, immersed in the above-mentioned aqueous phase liquid A and allowed to stand for 15 seconds, and then the aqueous phase liquid remaining on the front side of the base membrane is blown away by a wind knife, and the aqueous phase liquid remaining on the back side of the base membrane is wiped away by absorbent paper, and then the oil phase liquid B is poured on the surface of the base membrane (completely covering the surface of the base membrane) to carry out interfacial polymerization reaction for 25 seconds to form a polyamide desalination layer, and the excess oil phase liquid on the membrane surface is blown away by a wind knife, and then the membrane is placed in an oven at 60°C and dried for 2 minutes to obtain a polyamide composite reverse osmosis membrane.

[0058] The difference between the comparative example 1 and the embodiment 1 is that the aqueous phase liquid of the comparative example 1 does not contain ZIF-8 nanomaterials and chitosan quaternary ammonium salt, and the other conditions are the same as those of the embodiment 1.

[0059] Comparative Example 2

[0060] The difference between Comparative Example 2 and Comparative Example 1 is that: ZIF-8 nanomaterial with a concentration of 0.4 wt % and a particle size of 50 nm is added to the aqueous phase liquid of Comparative Example 2, and the rest is the same as Comparative Example 1.

[0061] Comparative Example 3

[0062] The difference between Comparative Example 3 and Comparative Example 1 is that a nanomaterial with a concentration of 0.8 wt % and a particle size of 50 nm is added to the aqueous phase liquid of Comparative Example 3, and the other conditions are the same as those of Comparative Example 1.

[0063] Comparative Example 4

[0064] The difference between Comparative Example 4 and Comparative Example 1 is that a nanomaterial with a concentration of 0.4 wt % and a particle size of 500 nm is added to the aqueous phase liquid of Comparative Example 4, and the other conditions are the same as those of Comparative Example 1.

[0065] test:

[0066] 1. Separation performance and antibacterial performance test of reverse osmosis membrane:

[0067] (1) On the first day and after 30 days of continuous use, the separation performance of the reverse osmosis membranes prepared in Examples 1 to 6 and Comparative Examples 1 to 4 was tested. The performance was mainly characterized by two characteristic parameters, namely, the water flux and the salt rejection rate of the membrane. The test results are shown in Table 1 below.

[0068] ① Water flux: refers to the volume of water passing through the effective unit area membrane per unit time under certain test conditions;

[0069] ②Desalination rate R, the calculation formula is: R = (1-C p / C f )*100%, where R is the interception rate or desalination rate, C p is the influent salt concentration, C f is the salt concentration of produced water;

[0070] The test conditions for the above-mentioned "water flux" and "salinity rejection rate" are: the feed liquid is a 500 ppm sodium chloride aqueous solution, the feed liquid temperature is 25° C., and the operating pressure is 70 psi (0.483 MPa).

[0071] (2) On the first day and after continuous use for 30 days, the antibacterial properties of the reverse osmosis membranes prepared in the above Examples 1 to 6 and Comparative Examples 2 to 4 were tested. The test method was as follows: Gram-negative Escherichia coli was used as a bacterial model. According to the National Standard of the People's Republic of China (GB / T 20944.3 2008), the antibacterial properties of the reverse osmosis membranes were tested by the bacterial liquid osmosis method. The number of colonies on each agar plate was calculated by the plate count method to analyze the antibacterial rate (K) of each membrane sample. The calculation formula was: K = (1-Nm / NO) × 100%; wherein Nm is the colony count (CFU / mL) of the reverse osmosis membrane sample prepared in each example; NO is the colony count (CFU / mL) of the reverse osmosis membrane sample prepared in Comparative Example 1. The specific test results are shown in Table 1 below.

[0072] Table 1 shows the test results of reverse osmosis membranes of Examples 1 to 6 and Comparative Examples 1 to 4

[0073]

[0074] As can be seen from the test results of Example 1 and Comparative Example 1 in Table 1, the present invention utilizes the reverse osmosis membrane modified in coordination with ZIF-8 nano material and chitosan quaternary ammonium salt, while improving the dispersibility of high-concentration ZIF-8 additives, it also brings the dual-effect improvement of permeation flux (GFD) and antibacterial performance, when adopting the ZIF-8 nano material of particle diameter 50nm, by the auxiliary dispersion of chitosan quaternary ammonium salt, the desalination performance of reverse osmosis membrane can be guaranteed. After 30 days of long-acting test, the reverse osmosis membrane modified in coordination with ZIF-8 nano material and chitosan quaternary ammonium salt can maintain good antibacterial effect. As can be seen from the test results of Comparative Examples 2 to 4 in Table 1, the simple ZIF-8 nano material, while improving the membrane permeation flux, destroys the integrity of the desalination layer due to the agglomeration between particles, causing the desalination capacity to weaken, and more easily causes this phenomenon under high concentration.

[0075] 2. Contact angle test:

[0076] The contact angle test was performed on the reverse osmosis membranes prepared in Example 1 and Comparative Example 1. The contact angle of the high-flux antibacterial reverse osmosis membrane prepared in Example 1 is as follows: Figure 1 As shown, the contact angle of the polyamide composite reverse osmosis membrane prepared in Comparative Example 1 is as shown Figure 2 As shown, from Figures 1-2It can be seen that the water contact angle of the high-flux antibacterial reverse osmosis membrane prepared in Example 1 of the present invention is smaller, indicating that the reverse osmosis membrane of the present invention has better hydrophilicity, better antibacterial performance and permeation flux.

[0077] In summary, the present invention successfully prepared a polyamide desalination layer with a positive surface charge by using ZIF-8 nanomaterials in conjunction with chitosan quaternary ammonium salt, so that the reverse osmosis membrane exhibits good permeability and antibacterial properties. ZIF-8 nanoparticles are embedded in the polyamide desalination layer as an additive. 2+ The positive charge of ZIF-8 nanomaterials, which is formed by the coordination bond with 2-methylimidazole, can destroy the cell membrane of negatively charged bacteria adsorbed on the membrane surface, achieving an antibacterial effect. At the same time, the imidazole substances slowly released by ZIF-8 nanomaterials belong to a category of organic antibacterial agents and have high bactericidal efficacy. 2+ They will accumulate on the surface of bacterial cell membranes, change the permeability of cell membranes, cause bacterial cytoplasm to outflow, and eventually lead to bacterial apoptosis.

[0078] In addition, ZIF-8 nano material is except bringing the promotion of antibacterial property, and the new fluid channel brought in the embedded polyamide desalination layer can effectively improve the permeation flux of reverse osmosis membrane. However, ZIF-8 nano material is very easy to reunite under high concentration, and is easy to form large particles in the interfacial polymerization stage, destroys the integrity of the polyamide desalination layer, and reduces the concentration of ZIF-8 material and then causes the long-term antibacterial performance to be impaired. In addition, ZIF-8 material can bring hydrophobic surface under high concentration, and according to the antibacterial mechanism, hydrophilic surface can increase the interaction between film and water molecules, thereby reducing the adsorption of bacteria, and the hydrophobic surface brought by ZIF-8 material may cause the accumulation of bacteria on the membrane surface. For this reason, the present invention has additionally added the dispersion of quaternary ammonium salt auxiliary ZIF-8 material in the aqueous phase solution, and the quaternary amine group added simultaneously can effectively improve the hydrophilicity of the membrane surface.

[0079] The preferred chitosan quaternary ammonium salt of the present invention is used as a surfactant, which can effectively prevent the agglomeration of ZIF-8 materials and make ZIF-8 have good dispersibility in the aqueous phase liquid. The addition of chitosan quaternary ammonium salt can improve the hydrophilicity of the membrane surface and bring about a hydrophilic membrane surface. At the same time, the quaternary ammonium salt cation interacts with the anionic components of the bacterial outer membrane, resulting in the destruction of the cell outer membrane, releasing the cytoplasm, and stopping the growth and proliferation of bacteria. Therefore, it can also be used as an auxiliary antibacterial material to further improve the antibacterial ability of the membrane surface.

[0080] The above are preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A high-flux antibacterial reverse osmosis membrane, characterized in that: The reverse osmosis membrane comprises a base membrane and a polyamide desalination layer; The polyamide desalination layer is formed on the surface of the base film by interfacial polymerization of acyl chloride monomers and aromatic amine monomers, and ZIF-8 nanomaterials are embedded in the polyamide desalination layer.

2. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 1, characterized in that: The method comprises the following steps: S1. Basement membrane preparation: provide a basement membrane and soak it in water for storage; S2, preparing aqueous phase liquid: dissolving chitosan quaternary ammonium salt, ZIF-8 nanomaterials and aromatic amine monomers in water, and ultrasonically dispersing to obtain aqueous phase liquid; S3, preparing the oil phase liquid: dissolving the acyl chloride monomer in an organic solvent to obtain an oil phase liquid; S4, preparation of reverse osmosis membrane: immerse the base membrane in the aqueous phase liquid for treatment, remove the residual aqueous phase liquid on the surface of the base membrane after taking it out, and then pour the oil phase liquid on the surface of the base membrane for interfacial polymerization reaction, remove the liquid on the membrane surface, dry it, and prepare a positively charged polyamide reverse osmosis membrane with ZIF-8 nanomaterials embedded inside.

3. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2, characterized in that: The concentration of chitosan quaternary ammonium salt in the aqueous phase is 0.5-5.0 wt %.

4. A method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2 or 3, characterized in that: The chitosan quaternary ammonium salt is hydroxypropyltrimethylammonium chloride chitosan, and the substitution degree of the chitosan quaternary ammonium salt is not less than 92.0%.

5. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2, characterized in that: The concentration of the ZIF-8 nanomaterial in the aqueous phase is 0.2-2.0 wt %.

6. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2 or 5, characterized in that: The particle size of the ZIF-8 nano material is 50 to 500 nm.

7. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2, characterized in that: The concentration of the aromatic amine monomer in the aqueous phase is 1.0-5.0 wt %.

8. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2 or 7, characterized in that: The aromatic amine monomer is selected from any one of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine and benzidine.

9. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2, characterized in that: The concentration of the acyl chloride monomer in the oil phase liquid is 0.02-0.3wt%, and the acyl chloride is selected from one or more of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, and cyclohexanetrichloride; the organic solvent is selected from one or more of n-hexane, cyclohexane, n-heptane, and isoparaffin solvents.

10. The method for preparing a high-flux antibacterial reverse osmosis membrane according to claim 2, characterized in that: The base membrane is first immersed in the aqueous phase liquid for 15 to 60 seconds, and the aqueous phase liquid remaining on the surface of the base membrane is removed after being taken out. Then, the oil phase liquid is poured on the surface of the base membrane for interfacial polymerization for 20 to 60 seconds to form a polyamide desalination layer, and the liquid on the membrane surface is removed. The membrane is dried at 60 to 80° C. for 1 to 5 minutes to prepare a positively charged polyamide reverse osmosis membrane with ZIF-8 nanomaterials embedded inside.

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