A high-bonding anti-fouling coating with adjustable charge function for filtration membranes, and a preparation method and application thereof

Abstract

The application discloses a high-bonding-force anti-pollution coating with an adjustable charge function for a filtering membrane and a preparation method and application thereof, which is attached to the surface of the filtering membrane and comprises a copolymer network formed by a water-soluble polymer, a polybasic phenol compound and a polyamine compound, and a trimethylol aminomethane hydrochloride; and the thickness is 10 nm-2 microns. The polybasic phenol compound and the polyamine compound are directly introduced into the water-soluble polymer system, and an interpenetrating copolymer network is formed by utilizing self-initiated oxidation polymerization reaction of the two. The copolymer network serves as a stable crosslinking framework, firmly anchors the water-soluble polymer on the surface of the filtering membrane, and endows the coating with excellent anti-shearing flushing capacity, thereby significantly prolonging the effective period of the membrane modification effect.

Description

Technical Field

[0001] This invention belongs to the field of filter membrane technology, specifically relating to a high-adhesion antifouling coating with adjustable charge function for filter membranes, its preparation method, and its application. Background Technology

[0002] Membrane separation technology, as a novel separation technology characterized by high efficiency, low energy consumption, and no phase change, plays a crucial role in water treatment, resource recovery, biomedicine, and chemical separation. Currently, the mainstream separation membranes in industry are mainly divided into two categories: inorganic membranes and organic membranes. Among them, organic separation membranes occupy the vast majority of the market share due to their significant advantages, including a wide selection of membrane-forming materials, separation precision covering the entire range from microfiltration, ultrafiltration, nanofiltration to reverse osmosis, and flexible membrane module forms.

[0003] However, in the long-term practical operation of organic separation membranes, membrane fouling has always been the core bottleneck restricting their large-scale promotion and stable operation. Commonly used organic separation membrane substrates (such as polysulfone, polyethersulfone, and polyvinylidene fluoride) typically have strong hydrophobicity. When microorganisms, colloidal particles, proteins, or solute macromolecules in the feed solution come into contact with the membrane surface, strong hydrophobic interactions and van der Waals forces are generated between the hydrophobic groups. These contaminants are prone to disordered adsorption, deposition, and accumulation on the membrane surface or inner pore walls, leading to membrane pore size shrinkage or even blockage. Membrane fouling not only causes a sharp decline in membrane permeate flux, increases operating energy consumption and cleaning frequency, but also significantly shortens the service life of membrane modules, imposing a huge economic burden on industrial production.

[0004] To address the hydrophobic fouling problem of organic membranes, hydrophilic modification of the membrane material surface to improve its anti-adhesion ability is the most direct and effective technical approach to reduce membrane fouling. Existing surface modification methods mainly include physical coating, surface adsorption, chemical graft copolymerization, and biomodification. Among these, surface coating modification using water-soluble polymers has become one of the most favored modification methods in industry due to its simple process, low raw material cost, and easy compatibility with existing continuous roll-to-roll production lines.

[0005] However, existing water-soluble polymer coating modification technologies still have the following significant drawbacks: First, poor interfacial adhesion and insufficient long-term operational stability. Water-soluble polymer coatings that rely solely on physical adsorption to bind to the membrane surface are prone to detachment and dissolution under the hydrodynamic shearing action of high-speed cross-flow scouring or high-pressure filtration, leading to a rapid loss of modification effect. Although introducing external cross-linking agents for chemical cross-linking can improve the mechanical strength of the coating to some extent, excessive cross-linking reactions will drastically consume the hydrophilic functional groups on the polymer chains, resulting in a severe decrease in the hydrophilicity of the coating, falling into the dilemma of "high strength and high hydrophilicity cannot be achieved simultaneously." Second, a lack of charge regulation capability. Contaminants in actual industrial feed solutions often carry specific charges. If the charge properties of the modified membrane surface are opposite to those of the contaminants, the strong electrostatic attraction will drastically aggravate the deposition and enrichment of contaminants on the membrane surface. Existing traditional hydrophilic coatings can usually only provide a unidirectional hydrophilic barrier, making it difficult to flexibly adjust the charge distribution and isoelectric point of the membrane surface according to the specific contamination system, and thus failing to achieve electrostatic repulsion and antifouling.

[0006] Therefore, how to develop an antifouling coating technology that can not only form a strong and stable bond with the surface of the filter membrane and maintain long-term operational stability, but also has the function of adjustable surface charge, and has a simple preparation process and controllable cost is a technical problem that urgently needs to be solved in the field of filter membranes. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-adhesion anti-fouling coating with adjustable charge function for use in filter membranes.

[0008] Another object of the present invention is to provide a method for preparing the above-mentioned high-adhesion anti-fouling coating.

[0009] Another object of the present invention is to provide the application of the above-mentioned high-adhesion anti-fouling coating.

[0010] The technical solution of the present invention is as follows:

[0011] A high-adhesion antifouling coating with adjustable charge function for use in filter membranes is attached to the surface of the filter membrane and comprises a copolymer network formed by a water-soluble polymer, a polyphenolic compound and a polyamine compound, and tris(hydroxymethyl)aminomethane hydrochloride; its thickness is 10 nm to 2 µm.

[0012] The water-soluble polymer is at least one of polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, and carboxymethyl cellulose;

[0013] The polyphenolic compound is at least one of catechol, p-methylcatechol, 3-methylcatechol, p-tert-butylcatechol, and tannic acid;

[0014] The polyamine compound is at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine with a molecular weight of 300 to 300,000.

[0015] In a preferred embodiment of the present invention, the water-soluble polymer is polyvinyl alcohol; the polyphenol compound is catechol; and the polyamine compound is triethylenetetramine.

[0016] In a preferred embodiment of the present invention, the filtration membrane is an ultrafiltration membrane, a microfiltration membrane, a nanofiltration membrane, or a reverse osmosis membrane.

[0017] The preparation method of the above-mentioned high-adhesion anti-fouling coating includes the following steps:

[0018] (1) Preparation of coating solution A: Dissolve the water-soluble polymer and polyphenol compound in pure water to form coating solution A;

[0019] (2) Preparation of coating solution B: Dissolve the polyamine compound and tris(hydroxymethyl)aminomethane hydrochloride in pure water to form coating solution B;

[0020] (3) Mixing and coating: Mix coating liquid A and coating liquid B immediately to obtain coating liquid C, and then coat coating liquid C onto the surface of the filter membrane within 2 minutes.

[0021] (4) Drying and curing: The coated filter membrane is placed in an oven to dry, and then placed in a storage room at a constant temperature of 35°C and a relative humidity of 70% for curing for 2 to 24 hours to obtain a modified filter membrane with an anti-fouling coating.

[0022] In a preferred embodiment of the present invention, the water-soluble polymer in the coating solution C has a mass concentration of 0.1% to 3%, the polyphenol compound has a mass concentration of 0.01% to 1%, the polyamine compound has a mass concentration of 0.005% to 1%, and the tris(hydroxymethyl)aminomethane hydrochloride has a concentration of 10 mM.

[0023] More preferably, in step (3), the pH of the coating solution C is 8 to 11; the coating solution A and the coating solution B are mixed at a volume ratio of 1:1.

[0024] In a preferred embodiment of the present invention, in step (4), the drying conditions are: drying at 90°C for 15 min.

[0025] A modified filter membrane includes a filter membrane and an antifouling coating attached to its surface, wherein the antifouling coating is the aforementioned high-adhesion antifouling coating.

[0026] The above-mentioned high-adhesion antifouling coatings are used in water treatment or industrial separation processes.

[0027] The above-mentioned modified filter membranes are used in water treatment or industrial separation processes.

[0028] The beneficial effects of this invention are:

[0029] 1. This invention directly introduces polyphenolic compounds and polyamine compounds into a water-soluble polymer system, utilizing their self-initiated oxidative polymerization to form an interpenetrating copolymer network. This copolymer network, acting as a stable crosslinking framework, firmly anchors the water-soluble polymer to the filter membrane surface, endowing the coating with excellent shear erosion resistance and significantly extending the effective period of membrane modification.

[0030] 2. By adjusting the composition ratio of polyphenolic compounds and polyamine compounds in the coating solution, the charge distribution characteristics and isoelectric point of the coating surface can be precisely adjusted. For target contamination systems with different charge characteristics, the membrane surface can be selectively modulated to have the same charge. Utilizing the electrostatic repulsion between like charges, the adhesion of contaminants can be further blocked, enhancing the antifouling ability under complex liquid conditions.

[0031] 3. Unlike traditional crosslinking agents that cause hydrophilicity degradation, the phenol-amine copolymer generated in situ in this invention contains abundant hydrophilic functional groups (such as hydroxyl and amino groups), which can maintain excellent surface hydrophilicity while strengthening the coating adhesion, and greatly slow down the flux decay rate during the filtration process.

[0032] 4. The coating preparation process of the present invention is mild and can be fully implemented using existing filter membrane production lines and coating equipment without the need for additional investment in expensive equipment upgrades. Moreover, the cost of raw and auxiliary materials is controllable, making it highly valuable for industrial application and promotion. Attached Figure Description

[0033] Figure 1 This is a comparison graph showing the change in flux retention rate over time in simulated cross-flow filtration tests of contaminated liquids in Examples 1, 2, and Comparative Example 1 of the present invention.

[0034] Figure 2 The graph shows the test results of the membrane surface Zeta potential under different pH conditions for Examples 1 and 2 of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be further explained and described below with reference to specific embodiments and accompanying drawings.

[0036] Unless otherwise specified, all raw materials, reagents or instruments used in the embodiments of this invention are conventional products that can be purchased commercially; where no specific technology, reaction conditions or test conditions are specified, they shall be carried out in accordance with conventional technical conditions in the field, conditions described in the literature or conditions recommended in the product instructions.

[0037] I. General preparation technology scheme of the anti-fouling coating modified film of the present invention

[0038] The present invention provides a high-adhesion antifouling coating with adjustable charge function for use in filter membranes, wherein the antifouling coating is bonded to the surface of the filter membrane and the coating thickness is 10 nm to 2 µm.

[0039] 1. Composition:

[0040] Water-soluble polymer: selected from at least one of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), and carboxymethyl cellulose (CMC);

[0041] Polyphenolic compounds: selected from at least one of catechol, p-methylcatechol, 3-methylcatechol, p-tert-butylcatechol, and tannic acid;

[0042] Polyamine compounds: selected from at least one of diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and polyethyleneimine (PEI) with a molecular weight of 300 to 300,000;

[0043] Buffer component: Tris-HCl (tris-hydroxymethylaminomethane hydrochloride).

[0044] 2. General preparation steps:

[0045] (1) Preparation of coating solution A: Dissolve the water-soluble polymer and polyphenol compound in pure water to form coating solution A;

[0046] (2) Preparation of coating solution B: Dissolve the polyamine compound and tris(hydroxymethyl)aminomethane hydrochloride in pure water to form coating solution B;

[0047] (3) Mixing and coating: Mix coating solution A and coating solution B immediately to obtain coating solution C (control the mass concentration of water-soluble polymer in coating solution C to be 0.1% to 3%, the mass concentration of polyphenol compound to be 0.01% to 1%, the mass concentration of polyamine compound to be 0.005% to 1%, the concentration of tris(hydroxymethyl)aminomethane hydrochloride to be 10 mM, and the pH to be 8 to 11); Coat the surface of filter membrane with coating solution C within 2 min after immediate mixing.

[0048] (4) Drying and curing: The coated filter membrane is placed in an oven to dry, and then placed in a storage room at a constant temperature of 35°C and a relative humidity of 70% for curing for 2 to 24 hours to obtain a modified filter membrane with an anti-fouling coating.

[0049] Application scope of the base membrane: The filter membrane can be selected from ultrafiltration membrane, microfiltration membrane, nanofiltration membrane or reverse osmosis membrane.

[0050] II. Specific Implementation Examples and Comparative Examples

[0051] Example 1

[0052] (1) Preparation of coating solution A: Polyvinyl alcohol (with a degree of hydrolysis of 95% and a viscosity of 5-6 mPa·s under the conditions of 20℃ and 4 wt% aqueous solution) and catechol are dissolved in pure water and stirred thoroughly to prepare coating solution A with a polyvinyl alcohol mass concentration of 0.4 wt% and a catechol mass concentration of 0.05 wt%.

[0053] (2) Preparation of coating solution B: Dissolve triethylenetetramine and tris(hydroxymethyl)aminomethane hydrochloride in pure water and dissolve them completely to prepare coating solution B with a triethylenetetramine mass concentration of 0.03 wt% and a tris(hydroxymethyl)aminomethane hydrochloride concentration of 20 mM.

[0054] (3) Mixing and coating: The coating solution A obtained in step (1) and the coating solution B obtained in step (2) are mixed evenly at a volume ratio of 1:1 to obtain coating solution C with a pH value of 9.5. In the mixed coating solution C, the mass concentration of polyvinyl alcohol is 0.2 wt%, the mass concentration of catechol is 0.025 wt%, the mass concentration of triethylenetetramine is 0.015 wt%, and the concentration of tris(hydroxymethyl)aminomethane hydrochloride is 10 mM. After preparation, coating solution C is coated on the surface of nanofiltration membrane base membrane (denoted as NF-0) within 2 min, and the coating amount is controlled so that the thickness of the coating after drying is 100 nm.

[0055] (4) Drying and curing: The coated nanofiltration membrane was placed in a 90℃ oven for 15 min to dry, and then placed in a constant temperature and humidity storage room at 35℃ and 70% relative humidity for 24 h to cure, thus forming the antifouling coating on the surface of the nanofiltration membrane, and the modified nanofiltration membrane sample SNF-1 was obtained.

[0056] Example 2

[0057] (1) Preparation of coating solution A: Polyvinyl alcohol (degree of alcoholysis is 95%, and the viscosity of 4 wt% aqueous solution at 20℃ is 5-6 mPa·s) and catechol are dissolved in pure water to prepare coating solution A with a polyvinyl alcohol mass concentration of 0.4 wt% and a catechol mass concentration of 0.05 wt%.

[0058] (2) Preparation of coating solution B: Dissolve triethylenetetramine and tris(hydroxymethyl)aminomethane hydrochloride in pure water to prepare coating solution B with a triethylenetetramine mass concentration of 0.3 wt% and a tris(hydroxymethyl)aminomethane hydrochloride concentration of 20 mM.

[0059] (3) Mixing and coating: The coating solution A obtained in step (1) and the coating solution B obtained in step (2) are mixed evenly at a volume ratio of 1:1 to obtain coating solution C with a pH value of 10.5. In the mixed coating solution C, the mass concentration of polyvinyl alcohol is 0.2 wt%, the mass concentration of catechol is 0.025 wt%, the mass concentration of triethylenetetramine is 0.15 wt%, and the concentration of tris(hydroxymethyl)aminomethane hydrochloride is 10 mM. The prepared coating solution C is coated on the surface of the nanofiltration membrane base (NF-0) within 2 min, and the coating thickness after drying is controlled to be 100 nm.

[0060] (4) Drying and curing: The coated nanofiltration membrane was placed in a 90℃ oven for 15 min to dry, and then placed in a constant temperature and humidity storage room at 35℃ and 70% relative humidity for 24 h to cure, thus obtaining the modified nanofiltration membrane sample SNF-2.

[0061] Comparative Example 1

[0062] Polyvinyl alcohol (95% degree of hydrolysis, viscosity of 5-6 mPa·s in a 4 wt% aqueous solution at 20°C) was dissolved in pure water to prepare a 0.2 wt% polyvinyl alcohol coating solution. This coating solution was applied to the surface of the same nanofiltration membrane base (NF-0) as in Example 1, and the coating thickness after drying was controlled to be 100 nm. It was then dried in a 90°C oven for 15 min, and then aged in a constant temperature and humidity storage room at 35°C and 70% relative humidity for 24 h to obtain the comparative nanofiltration membrane sample PNF.

[0063] III. Performance Evaluation Methods

[0064] 1. Evaluation of Membrane Surface Hydrophilicity (Water Contact Angle Test): The water contact angle of the membrane surface was measured using an optical contact angle meter (model: JCY-1, made in China). Test conditions: ambient temperature 25.0 ± 2.0℃, relative humidity 60% ± 5%. During the test, pure water was dropped onto the surface of the membrane under test. At least five parallel tests were performed randomly at different locations on the same membrane sample, and the average value was taken as the final water contact angle data. The smaller the water contact angle value, the better the hydrophilicity of the membrane surface.

[0065] 2. Evaluation of Antifouling Coating Adhesion and Long-Term Stability (Pure Water Rinsing Test): The membrane to be tested was fixed in the mold of the flat sheet membrane testing equipment. Under the temperature condition of 50℃ and cross-flow filtration mode, pure water was continuously circulated and rinsed on the membrane surface. After rinsing for 24 hours, the membrane was removed and dried, and its surface water contact angle was measured again. The long-term stability of the antifouling coating and the interfacial adhesion were evaluated by the ability to retain hydrophilicity.

[0066] 3. Antifouling Performance Evaluation (Simulated Fouled Feed Solution Filtration Test): An organic-inorganic composite simulated fouled feed solution was prepared, with the following composition: sodium alginate 5000 ppm + CaCl2 50 ppm + MgCl2 50 ppm + Na2CO3 100 ppm. Test Procedure: The membrane under test was loaded into the mold of the flat-panel membrane fouling test equipment and circulated using the fouled feed solution in cross-flow filtration mode (operating pressure 6.9 bar, feed solution temperature 25℃). The effluent flux was tested and recorded at time points (0h, 2h, 4h, 6h, 8h, and 24h), and the flux retention rate was calculated to evaluate the membrane's antifouling performance.

[0067] 4. Zeta charge test on membrane surface: The membrane surface potential was characterized using a solid-state Zeta potential analyzer (Antonpah, Austria, model: Surpass 3). Membrane sheets were cut to 1 cm × 2 cm dimensions and placed in the sample cell. A 1 mmol / L KCl aqueous solution was used as the electrolyte test solution. The pH of the test solution was adjusted using dilute hydrochloric acid (HCl) and dilute sodium hydroxide (NaOH) solutions (test range pH 4–9), and the change in Zeta potential with pH was recorded.

[0068] IV. Test Results and Data Analysis

[0069] 1. Analysis of hydrophilicity and coating bonding stability data

[0070] Table 1 shows the surface water contact angles of Examples 1-2, Comparative Example 1, and the original base film (NF-0), as well as the water contact angle test results after 24 hours of rinsing with pure water at 50°C.

[0071] Table 1 Evaluation results of hydrophilic and anti-fouling coating adhesion tests

[0072] Embodiment Initial water contact angle (°) Contact angle after 24 h scouring test (°) Original sample NF-0 56 54 Comparative Example 1 (PNF) 35 52 Example 1 (SNF-1) 28 29 Example 2 (SNF-2) 32 31

[0073] Data Analysis: Table 1 shows that the water contact angle of the original unmodified nanofiltration membrane base (NF-0) was 56°. After adding the hydrophilic coating, the initial contact angles of Comparative Example 1 (PNF), Example 1 (SNF-1), and Example 2 (SNF-2) all decreased significantly (to 35°, 28°, and 32°, respectively), indicating that the hydrophilicity of the membrane surface was improved.

[0074] After being continuously circulated and rinsed with pure water at 50℃ for 24 hours, the water contact angle of Comparative Example 1 (PNF) was significantly restored to 52° due to poor adhesion of traditional physical coating and coating peeling. It was basically at the same level as the original base film NF-0 (54°), and the hydrophilicity could not be maintained for a long time.

[0075] After a strong rinsing test, the water contact angles of Examples 1 (SNF-1) and 2 (SNF-2) of this invention remained at 29° and 31°, respectively, showing essentially no change compared to before rinsing (28° and 32°). This result strongly demonstrates that, through the technical solution of this invention, the copolymer network formed by the in-situ polymerization of polyphenols and polyamines effectively and firmly binds the water-soluble polymer to the nanofiltration membrane surface, significantly improving the coating adhesion and achieving long-term stability of hydrophilicity.

[0076] 2. Analysis of Simulated Pollution Test Data

[0077] The flux retention rate of each modified nanofiltration membrane during the simulated circulating filtration process of polluted liquid changes over time (0 h, 2 h, 4 h, 6 h, 8 h, 24 h) as shown below. Figure 1 As shown. Specific flux retention test data are as follows:

[0078] At 0 h: the flux retention rates of Comparative Example 1 (PNF), Example 1 (SNF-1), and Example 2 (SNF-2) were all 100.0%;

[0079] At 2 h: the flux retention rate of Comparative Example 1 (PNF) rapidly decreased to approximately 78.0%; Example 1 (SNF-1) maintained at 98.0%; Example 2 (SNF-2) maintained at 97.0%.

[0080] At 4 h: Comparative Example 1 (PNF) maintained a flux retention rate of 76.0%; Example 1 (SNF-1) maintained 95.0%; Example 2 (SNF-2) maintained 89.0%.

[0081] At 6 h: Comparative Example 1 (PNF) maintained a flux retention rate of 76.0%; Example 1 (SNF-1) maintained 93.0%; Example 2 (SNF-2) maintained 89.0%.

[0082] At 8 h: the flux retention rate of Comparative Example 1 (PNF) decreased to 72.0%; Example 1 (SNF-1) remained at 95.0%; Example 2 (SNF-2) remained at 89.0%.

[0083] At 24 h: the flux retention rate of Comparative Example 1 (PNF) decreased sharply to 54.0%; while the flux retention rate of Example 1 (SNF-1) was as high as 72.0% and that of Example 2 (SNF-2) was as high as 68.0%.

[0084] Data analysis: by Figure 1It can be seen that after 24 hours of continuous contamination testing, the flux retention rates of the modified nanofiltration membranes in Examples 1 and 2 were significantly higher than those in Comparative Example 1. This strongly demonstrates that the coating constructed using the technical solution of this invention can effectively inhibit the deposition of pollutants and significantly improve the antifouling performance of the nanofiltration membrane.

[0085] 3. Analysis of Zeta charge and tunability data on membrane surface

[0086] The zeta potential test results of the modified nanofiltration membranes of Example 1 (SNF-1) and Example 2 (SNF-2) under different pH conditions (pH 4-9) are as follows: Figure 2 As shown. Specific test data is as follows:

[0087] At pH = 4: the Zeta potential of Example 1 (SNF-1) was -22 mV; the Zeta potential of Example 2 (SNF-2) was +12 mV;

[0088] At pH = 5: the Zeta potential of Example 1 (SNF-1) was -38 mV; the Zeta potential of Example 2 (SNF-2) was +11 mV;

[0089] At pH = 6: the Zeta potential of Example 1 (SNF-1) was -59 mV; the Zeta potential of Example 2 (SNF-2) was +9 mV;

[0090] At pH = 7: the Zeta potential of Example 1 (SNF-1) was -73 mV; the Zeta potential of Example 2 (SNF-2) was +5 mV;

[0091] At pH = 8: the Zeta potential of Example 1 (SNF-1) was -75 mV; the Zeta potential of Example 2 (SNF-2) was -15 mV;

[0092] At pH = 9: the Zeta potential of Example 1 (SNF-1) was -76 mV; the Zeta potential of Example 2 (SNF-2) was -55 mV.

[0093] Data Analysis:

[0094] Depend on Figure 2 It can be known that:

[0095] For Example 1 (SNF-1), the membrane surface exhibited a negative charge across the entire tested pH range of 4–9, and a strong negative charge as high as -73 mV at neutral conditions (pH 7). Because the pollutant sodium alginate used in this test is negatively charged, Example 1 achieved the highest flux retention rate through strong electrostatic repulsion. Figure 1 The 24-hour rate was 72%.

[0096] For Example 2 (SNF-2), by increasing the proportion of polyamine compounds, the isoelectric point (pH) of the membrane surface was significantly increased to above 7 (approximately pH 7.3). Under neutral conditions (pH 7), the membrane surface became positively charged (Zeta potential of +5 mV).

[0097] The above results fully confirm that by adjusting the ratio of polyphenolic compounds to polyamine compounds, the surface charge distribution and polarity of the formed coating can be precisely adjusted, thereby enabling customized repulsion control of industrial pollutants with different charge properties and achieving adjustable surface charge.

[0098] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A high-adhesion antifouling coating with adjustable charge function for use in filter membranes, characterized in that: It adheres to the surface of the filter membrane and comprises a copolymer network formed by water-soluble polymers, polyphenolic compounds and polyamine compounds, and tris(hydroxymethyl)aminomethane hydrochloride; its thickness is 10 nm to 2 µm. The water-soluble polymer is at least one of polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, and carboxymethyl cellulose; The polyphenolic compound is at least one of catechol, p-methylcatechol, 3-methylcatechol, p-tert-butylcatechol, and tannic acid; The polyamine compound is at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine with a molecular weight of 300 to 300,000.

2. The high-adhesion anti-fouling coating as described in claim 1, characterized in that: The water-soluble polymer is polyvinyl alcohol; the polyphenol compound is catechol; and the polyamine compound is triethylenetetramine.

3. The high-adhesion anti-fouling coating as described in claim 1 or 2, characterized in that: The filtration membrane is an ultrafiltration membrane, microfiltration membrane, nanofiltration membrane, or reverse osmosis membrane.

4. A method for preparing a high-adhesion anti-fouling coating according to any one of claims 1 to 3, characterized in that: Includes the following steps: (1) Preparation of coating solution A: Dissolve the water-soluble polymer and polyphenol compound in pure water to form coating solution A; (2) Preparation of coating solution B: Dissolve the polyamine compound and tris(hydroxymethyl)aminomethane hydrochloride in pure water to form coating solution B; (3) Mixing and coating: Mix coating liquid A and coating liquid B immediately to obtain coating liquid C, and then coat coating liquid C onto the surface of the filter membrane within 2 minutes. (4) Drying and curing: The coated filter membrane is placed in an oven to dry, and then placed in a storage room at a constant temperature of 35°C and a relative humidity of 70% for 2 to 24 hours to obtain a modified filter membrane with an anti-fouling coating.

5. The preparation method according to claim 4, characterized in that: In the coating solution C, the mass concentration of the water-soluble polymer is 0.1% to 3%, the mass concentration of the polyphenol compound is 0.01% to 1%, the mass concentration of the polyamine compound is 0.005% to 1%, and the concentration of tris(hydroxymethyl)aminomethane hydrochloride is 10 mM.

6. The preparation method according to claim 5, characterized in that: In step (3), the pH of coating solution C is 8 to 11; coating solution A and coating solution B are mixed at a volume ratio of 1:

1.

7. The preparation method according to claim 4, characterized in that: In step (4), the drying conditions are: drying at 90°C for 15 min.

8. A modified filter membrane, characterized in that: It includes a filter membrane and an antifouling coating attached to its surface, said antifouling coating being the high-adhesion antifouling coating as described in any one of claims 1 to 3.

9. The application of the high-adhesion antifouling coating according to any one of claims 1 to 3 in water treatment or industrial separation processes.

10. The application of the modified filter membrane according to claim 8 in water treatment or industrial separation processes.

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