Ro membrane filter element for water purifier

Abstract

The invention relates to the technical field of reverse osmosis (RO) membranes, in particular to a ro membrane filter element for a water purifier. A ro membrane filter element for a water purifier is a polyethersulfone membrane with a hydrophilic modifier-polydopamine coating deposited on the surface, and the hydrophilic modifier is one or more of polyethylene glycol, hexanehexol and 3-sulfopropyl tetradecyl dimethyl betaine. The ro membrane filter element for the water purifier disclosed by the invention has extremely high anti-pollution performance.

Description

Technical Field

[0001] The present application relates to the technical field of reverse osmosis (RO) membranes, and more specifically, to a RO membrane filter element for a water purifier. Background Art

[0002] Reverse osmosis membrane (RO membrane) is a semi-permeable membrane with specific properties that is artificially synthesized. This membrane allows solvents to pass through, but solutes cannot pass through. It is the core component of reverse osmosis technology. The surface pore size of the reverse osmosis membrane is very small, ranging from 0.5-10nm, which can effectively remove various pollutants in the water, including microorganisms, salts, etc., thereby achieving the effect of purifying water quality.

[0003] Polyethersulfone membrane is a common polymer membrane material. It has excellent tensile strength, chemical stability, heat resistance, pressure resistance, and a wide pH range, so it is widely used in the field of reverse osmosis RO membranes. However, polyethersulfone membranes are highly hydrophobic, and when using polyethersulfone membranes, polyethersulfone membranes are easily adsorbed by pollutants due to hydrophobic-hydrophobic interactions, resulting in the accumulation of pollutants, which in turn affects the normal use of polyethersulfone membranes. Summary of the invention

[0004] In order to improve the defect of poor anti-pollution performance of conventional polyethersulfone membranes, the present application provides a RO membrane filter element for a water purifier.

[0005] The present application provides a RO membrane filter element for a water purifier, which adopts the following technical solution:

[0006] A RO membrane filter element for a water purifier is a polyethersulfone membrane with a hydrophilic modifier-polydopamine coating deposited on the surface, wherein the hydrophilic modifier is one or more of polyethylene glycol, hexadecyl hexacol and 3-sulfopropyl tetradecyl dimethyl betaine.

[0007] Preferably, the hydrophilic modifier is 3-sulfopropyltetradecyl dimethyl betaine.

[0008] Preferably, the deposition method of the hydrophilic modifier-polydopamine coating is: first, 3-sulfopropyltetradecyl dimethyl betaine is added to 50 ml of Tris buffer containing dopamine hydrochloride at a concentration of 1.8-2.2 mg / ml, and then the polyethersulfone membrane is immersed in the above solution, reacted at room temperature for 3-5 hours, and then rinsed with deionized water and dried with nitrogen to obtain a polyethersulfone membrane with a hydrophilic modifier-polydopamine coating deposited thereon.

[0009] The pollution of RO membrane is mainly caused by the hydrophobic-hydrophobic interaction between the membrane and the pollutants. Therefore, hydrophilic modification of RO membrane is the main method to improve the anti-pollution performance of RO membrane. In this regard, the applicant learned that polyethylene glycol has extremely strong hydrophilic properties and can form a hydration layer on the surface of RO membrane, thereby hindering the adsorption of pollutants on the surface of RO membrane, thereby enabling RO membrane to obtain excellent anti-pollution performance.

[0010] However, the connection performance between polyethersulfone membrane and polyethylene glycol is poor. If the polyethersulfone membrane is directly modified with polyethylene glycol for hydrophilicity, the polyethylene glycol will be separated from the polyethersulfone membrane in a short time. The polydopamine coating can form a strong connection between inert surfaces or functional polymers through Schiff base reaction or Michael addition reaction. At the same time, there are a large number of amino groups on the surface of the polydopamine coating. Therefore, polyethylene glycol can be connected to the surface of the polydopamine coating through external modification. Under the action of the polydopamine coating, the polyethylene glycol and the polyethersulfone membrane will obtain an extremely good connection effect.

[0011] However, polyethylene glycol contains only one oxygen atom in each repeating unit, so it can only form a hydrogen bond with one water molecule, while the hexane hexacol molecule contains more hydroxyl groups, which can form more hydrogen bonds between water molecules, promote the transfer of water molecules, and further form a hydration layer on the surface of the polyethersulfone membrane, effectively improving the anti-fouling performance of the RO membrane.

[0012] 3-Sulfopropyltetradecyl dimethyl betaine belongs to sulfobetaine, which can combine with more water molecules than hexane. At the same time, 3-Sulfopropyltetradecyl dimethyl betaine can also be co-deposited with polydopamine, thereby achieving a better connection effect between 3-Sulfopropyltetradecyl dimethyl betaine and polyethersulfone membrane.

[0013] In summary, in order to improve the hydrophilicity of polyethersulfone membrane, with the assistance of polydopamine coating, the hydrophilic modifier can be specifically selected as polyethylene glycol, hexadecyl dimethyl betaine and 3-sulfopropyl tetradecyl dimethyl betaine. Among them, when 3-sulfopropyl tetradecyl dimethyl betaine is selected, the prepared RO membrane will have a better hydrophilic effect, and thus obtain better anti-fouling performance.

[0014] Preferably, the hydrophilic modifier is hexanehexacol and 3-sulfopropyltetradecyl dimethyl betaine.

[0015] Preferably, the deposition method of the hydrophilic modifier-polydopamine coating comprises the following steps:

[0016] S1. First, 3-sulfopropyl tetradecyl dimethyl betaine is added to 50 ml of a Tris buffer solution containing dopamine hydrochloride at a concentration of 1.8-2.2 mg / ml, and then a polyethersulfone membrane is immersed in the above solution. After reacting at room temperature for 3-5 hours, the membrane is rinsed with deionized water and dried with nitrogen gas to obtain a polyethersulfone membrane with a 3-sulfopropyl tetradecyl dimethyl betaine-polydopamine coating deposited thereon;

[0017] S2. First, hexamethylenetetradecyl dimethyl betaine-polydopamine coating-deposited polyethersulfone membrane is dissolved in 1 wt% triethylamine aqueous solution, and then the polyethersulfone membrane with 3-sulfopropyltetradecyl dimethyl betaine-polydopamine coating is immersed in the hexamethylenetetradecyl dimethyl betaine-polydopamine aqueous solution for 20-40 minutes, and finally rinsed with deionized water and dried with nitrogen to obtain a polyethersulfone membrane with hydrophilic modifier-polydopamine coating deposition.

[0018] Compared with selecting 3-sulfopropyl tetradecyl dimethyl betaine alone as a hydrophilic modifier, the simultaneous use of hexadecyl hexaol and 3-sulfopropyl tetradecyl dimethyl betaine will enable the polyethersulfone membrane to obtain better anti-fouling performance. The reason is that hexadecyl hexaol is connected to the surface of the polydopamine coating through external modification, while 3-sulfopropyl tetradecyl dimethyl betaine exists inside the polydopamine coating through co-deposition. Therefore, the two will have an internal and external synergistic effect, thereby enabling the RO membrane to obtain a better hydrophilic effect, which is ultimately manifested as a better anti-fouling performance.

[0019] Preferably, the addition amount of the 3-sulfopropyltetradecyl dimethyl betaine is 40-50 mg, and the concentration of the hexadecene is 1-5 wt %.

[0020] When hexanehexaol and 3-sulfopropyltetradecyl dimethyl betaine are added in the above amounts and concentrations, the prepared RO membrane will obtain a better hydrophilic effect, thereby significantly improving the anti-pollution performance of the RO membrane.

[0021] Preferably, in S2, a reversible acylhydrazone diol is added simultaneously with the addition of hexanediol.

[0022] During the long-term use of RO membranes, micro-damage to the polydopamine coating is likely to lead to further adhesion of pollutants, and the self-repair function of the polydopamine coating can effectively improve the above problems. Self-repair includes autonomous self-repair and non-autonomous self-repair. Autonomous self-repair does not require any additional external triggers. The damage itself is the stimulus for self-repair. The repair process is carried out autonomously within the material structure. In order to promote the self-repair function of polymers, non-covalent bonds such as hydrogen bonds, ionic interactions or metal-ligand interactions and reversible covalent bonds such as disulfide bonds or acylhydrazone bonds are usually introduced into the polymer.

[0023] In the present application, while adding hexane hexol, reversible acylhydrazone diol is also added, so that non-covalent hydrogen bonds and reversible covalent acylhydrazone bonds exist on the surface of the polydopamine coating at the same time, thereby promoting the hydrophilic modified material-polydopamine coating to have certain self-healing properties, thereby obtaining better durability.

[0024] Preferably, the concentration ratio of hexadecene to reversible acylhydrazone diol is (1-2): (1-2).

[0025] When the above concentration ratio of hexane hexanol and reversible acylhydrazone diol is used, the prepared hydrophilic modified material-polydopamine coating will have better self-healing performance, thereby obtaining better durability.

[0026] Preferably, the preparation method of the reversible acylhydrazone diol is:

[0027] 20-30g of p-hydroxybenzaldehyde is dissolved in 50-70ml of isopropanol, 15-20g of adipic acid dihydrazide is dissolved in 70-90ml of glacial acetic acid, and then the two are mixed evenly at a temperature of 60-80°C, and then filtered, washed with ethanol and deionized water in turn to remove impurities, and finally dried to obtain a reversible acylhydrazone diol.

[0028] In summary, this application has the following beneficial effects:

[0029] 1. The connection performance between polyethersulfone membrane and polyethylene glycol is poor. If the polyethersulfone membrane is directly modified with polyethylene glycol for hydrophilicity, polyethylene glycol will be separated from the polyethersulfone membrane body in a short time. The polydopamine coating can form a strong connection between the inert surface or functional polymers through Schiff base reaction or Michael addition reaction. At the same time, there are a large number of amino groups on the surface of the polydopamine coating. Therefore, polyethylene glycol can be connected to the surface of the polydopamine coating through external modification. Under the action of the polydopamine coating, an extremely good connection effect will be obtained between polyethylene glycol and the polyethersulfone membrane.

[0030] 2. Polyethylene glycol contains only one oxygen atom in each repeating unit, so it can only form a hydrogen bond with one water molecule, while the hexane hexacol molecule contains more hydroxyl groups, thus forming more hydrogen bonds between water molecules, promoting the transfer of water molecules, and further forming a hydration layer on the surface of the polyethersulfone membrane, effectively improving the anti-fouling performance of the RO membrane.

[0031] 3. 3-Sulfopropyltetradecyl dimethyl betaine is a sulfobetaine. Compared with hexane hexol, it can combine with more water molecules. At the same time, 3-Sulfopropyltetradecyl dimethyl betaine can also be co-deposited with polydopamine, thereby promoting a better connection effect between 3-Sulfopropyltetradecyl dimethyl betaine and polyethersulfone membrane, and promoting the prepared RO membrane to have a better hydrophilic effect, thereby obtaining a better anti-fouling performance.

[0032] 4. Compared with selecting 3-sulfopropyl tetradecyl dimethyl betaine alone as a hydrophilic modifier, the simultaneous use of hexadecyl hexacol and 3-sulfopropyl tetradecyl dimethyl betaine will enable the polyethersulfone membrane to obtain better anti-fouling performance. The reason is that hexadecyl hexacol is connected to the surface of the polydopamine coating through external modification, while 3-sulfopropyl tetradecyl dimethyl betaine exists inside the polydopamine coating through co-deposition. Therefore, the two will have an internal and external synergistic effect, thereby enabling the RO membrane to obtain a better hydrophilic effect, which is ultimately manifested as a better anti-fouling performance. DETAILED DESCRIPTION

[0033] The present application is further described in detail below in conjunction with Examples 1 to 9 and Comparative Example 1.

[0034] raw material

[0035] Polyethylene glycol, triethylamine, p-hydroxybenzaldehyde, isopropanol, adipic acid dihydrazide, glacial acetic acid, and Tris buffer were purchased from MERCK;

[0036] Dopamine hydrochloride was purchased from MACKLIN;

[0037] Hexacol Jinan Shuangshi;

[0038] 3-sulfopropyltetradecyl dimethyl betaine subfamily shares;

[0039] Polyethersulfone membrane Zhongke Ruiyang.

[0040] Example 1

[0041] A RO membrane filter element for a water purifier is a polyethersulfone membrane with a hydrophilic modifier-polydopamine coating deposited on the surface, wherein the hydrophilic modifier is polyethylene glycol.

[0042] A method for preparing a RO membrane filter element for a water purifier comprises the following steps:

[0043] S1. First, the polyethersulfone membrane is immersed in 50 ml of a Tris buffer solution containing dopamine hydrochloride at a concentration of 2 mg / ml, reacted at room temperature for 4 hours, then rinsed with deionized water, and dried with nitrogen gas to obtain a polyethersulfone membrane with a polydopamine coating deposited thereon;

[0044] S2. Add polyethylene glycol to a 1wt% triethylamine aqueous solution to a polyethylene glycol concentration of 3wt%, then soak the polyethersulfone membrane with a polydopamine coating in the polyethylene glycol-triethylamine aqueous solution for 30 minutes, and finally rinse with deionized water and blow dry with nitrogen to obtain a RO membrane filter element for a water purifier.

[0045] Example 2

[0046] The difference from Example 1 is that the hydrophilic modified substance is hexadecene.

[0047] A method for preparing a RO membrane filter element for a water purifier comprises the following steps:

[0048] S1. First, the polyethersulfone membrane is immersed in 50 ml of a Tris buffer solution containing dopamine hydrochloride at a concentration of 2 mg / ml, reacted at room temperature for 4 hours, then rinsed with deionized water, and dried with nitrogen gas to obtain a polyethersulfone membrane with a polydopamine coating deposited thereon;

[0049] S2. Dissolve hexacol in a 1wt% triethylamine aqueous solution to a hexacol concentration of 3wt%, then soak the polyethersulfone membrane with a polydopamine coating in the hexacol-triethylamine aqueous solution for 30 minutes, and finally rinse with deionized water and blow dry with nitrogen to obtain a RO membrane filter element for a water purifier.

[0050] Example 3

[0051] The difference from Example 1 is that the hydrophilic modified substance is 3-sulfopropyltetradecyl dimethyl betaine.

[0052] A method for preparing a RO membrane filter element for a water purifier is as follows:

[0053] First, 45 mg of 3-sulfopropyltetradecyl dimethyl betaine was added to 50 ml of Tris buffer containing dopamine hydrochloride at a concentration of 2 mg / ml, and then the polyethersulfone membrane was immersed in the above solution. After reacting at room temperature for 4 hours, it was rinsed with deionized water and dried with nitrogen to obtain a RO membrane filter element for a water purifier.

[0054] Example 4

[0055] The difference from Example 1 is that the hydrophilic modified substances are 3-sulfopropyltetradecyl dimethyl betaine and hexanehexatin.

[0056] A method for preparing a RO membrane filter element for a water purifier comprises the following steps:

[0057] S1. First, 45 mg of 3-sulfopropyl tetradecyl dimethyl betaine was added to 50 ml of Tris buffer containing dopamine hydrochloride at a concentration of 2 mg / ml, and then a polyethersulfone membrane was immersed in the above solution. After reacting at room temperature for 4 hours, the membrane was rinsed with deionized water and dried with nitrogen gas to obtain a polyethersulfone membrane with 3-sulfopropyl tetradecyl dimethyl betaine-polydopamine coating deposited thereon;

[0058] S2. First, dissolve hexacol in a 1wt% triethylamine aqueous solution to a hexacol concentration of 3wt%, then soak the polyethersulfone membrane deposited with a 3-sulfopropyltetradecyl dimethyl betaine-polydopamine coating in the hexacol-triethylamine aqueous solution for 30 minutes, and finally rinse with deionized water and blow dry with nitrogen to obtain a RO membrane filter element for a water purifier.

[0059] Example 5-Example 6

[0060] The difference from Example 4 is that the amount of 3-sulfopropyltetradecyl dimethyl betaine added and the concentration of hexadecene are different, as shown in Table 1.

[0061] Table 1 The amount or concentration of each component added in the RO membrane filter element for water purifier of Example 4-Example 6

[0062]

[0063] Example 7

[0064] The difference from Example 4 is that in S2, a reversible acylhydrazone diol is added at the same time as hexane hexol;

[0065] The preparation method of reversible acylhydrazone diol is:

[0066] 25 g of p-hydroxybenzaldehyde was dissolved in 60 ml of isopropanol, and 18 g of adipic acid dihydrazide was dissolved in 80 ml of glacial acetic acid. The two were then mixed evenly at 70° C., filtered, washed with ethanol and deionized water in turn to remove impurities, and finally dried to obtain a reversible acylhydrazone diol.

[0067] A method for preparing a RO membrane filter element for a water purifier comprises the following steps:

[0068] S1. First, 45 mg of 3-sulfopropyl tetradecyl dimethyl betaine was added to 50 ml of Tris buffer containing dopamine hydrochloride at a concentration of 2 mg / ml, and then a polyethersulfone membrane was immersed in the above solution. After reacting at room temperature for 4 hours, the membrane was rinsed with deionized water and dried with nitrogen gas to obtain a polyethersulfone membrane with 3-sulfopropyl tetradecyl dimethyl betaine-polydopamine coating deposited thereon;

[0069] S2. First, hexamethylenetetradecyl dimethyl betaine-polydopamine coating-deposited polyethersulfone membrane was immersed in the hexamethylenetetradecyl dimethyl betaine-triethylamine aqueous solution for 30 minutes, and finally rinsed with deionized water and dried with nitrogen to obtain a ro membrane filter element for a water purifier.

[0070] Example 8-Example 9

[0071] The difference from Example 7 is that the concentration ratio of hexane hexanol and reversible acylhydrazone diol is different, as shown in Table 2.

[0072] Table 2 Concentration ratio of hexane hexanol and reversible acylhydrazone diol in Example 7-Example 9

[0073] Example 7 Example 8 Example 9 Hexacol 1.5 2 1 Reversible acylhydrazone diol 1.5 1 2

[0074] Comparative Example 1

[0075] A RO membrane filter element for a water purifier, which is only a polyethersulfone membrane.

[0076] Performance testing

[0077] 1. Anti-pollution performance test

[0078] Three samples were taken from Examples 1 to 7 and Comparative Example 1, and then a bovine serum albumin solution was used as a feed solution, wherein the bovine serum albumin concentration was 0.5 mg / ml, and a permeation test was performed at 20 bar for 10 h;

[0079] The permeation flux 10 minutes before the test was defined as the original flux, and the permeation flux 10 minutes after 10 hours was defined as the test flux. Finally, the flux decline rate was calculated to characterize the anti-pollution performance, and the average value was taken.

[0080] Flux decrease rate = (original flux - test flux) / original flux × 100%.

[0081] The test data are shown in Table 3.

[0082] Table 3 Anti-pollution performance of Example 1 to Example 7 and Comparative Example 1

[0083] Flux decline rate / % Flux decline rate / % Example 1 44.3％ Example 5 22.3％ Example 2 30.1％ Example 6 23.0％ Example 3 25.7％ Example 7 19.4％ Example 4 19.2％ Comparative Example 1 76.9％

[0084] 2. Durability test

[0085] Three samples were taken from Example 4 and Example 7-Example 9 respectively, and then the samples were tested one hundred times with reference to the above anti-pollution performance test. A flushing operation was performed before each test. Finally, the difference between the flux reduction rate at the first time and the flux reduction rate at the hundredth time was calculated, recorded as the durability rate and the average value was taken.

[0086] The test data are shown in Table 4.

[0087] Table 4 Durability of Example 4 and Example 7-Example 9

[0088] Durability / % Durability / % Example 4 11.8％ Example 8 4.9％ Example 7 4.6％ Example 9 5.1％

[0089] Referring to Example 1 and Comparative Example 1 and in combination with Table 3, it can be seen that the flux reduction rate of Example 1 is significantly reduced compared with Comparative Example 1, which indicates that depositing a polyethylene glycol-polydopamine coating on the surface of the polyethersulfone membrane can effectively improve the anti-fouling performance of the polyethersulfone membrane.

[0090] The reason is that the pollution of RO membrane is mainly caused by the hydrophobic-hydrophobic effect between the membrane and the pollutants. Therefore, hydrophilic modification of the RO membrane is the main method to improve the anti-pollution performance of the RO membrane. In this regard, the applicant learned that polyethylene glycol has extremely strong hydrophilic properties. It can form a hydration layer on the surface of the RO membrane, thereby hindering the adsorption of pollutants on the surface of the RO membrane, thereby enabling the RO membrane to obtain excellent anti-pollution performance.

[0091] However, the connection performance between polyethersulfone membrane and polyethylene glycol is poor. If the polyethersulfone membrane is directly modified with polyethylene glycol for hydrophilicity, the polyethylene glycol will be separated from the polyethersulfone membrane in a short time. The polydopamine coating can form a strong connection between inert surfaces or functional polymers through Schiff base reaction or Michael addition reaction. At the same time, there are a large number of amino groups on the surface of the polydopamine coating. Therefore, polyethylene glycol can be connected to the surface of the polydopamine coating through external modification. Under the action of the polydopamine coating, the polyethylene glycol and the polyethersulfone membrane will obtain an extremely good connection effect.

[0092] With reference to Examples 1 to 3 and in combination with Table 3, it can be seen that, relative to Example 1, the flux reduction rate of Example 2 is significantly reduced, and the flux reduction rate of Example 3 is further reduced. This indicates that among the hydrophilic modifiers, when 3-sulfopropyltetradecyl dimethyl betaine is selected, the anti-fouling performance of the polyethersulfone membrane is the best, followed by hexadecene, and polyethylene glycol is relatively poor.

[0093] The reason is that polyethylene glycol contains only one oxygen atom in each repeating unit, so it can only form a hydrogen bond with one water molecule, while the hexane hexacol molecule contains more hydroxyl groups, which can form more hydrogen bonds between water molecules, promote the transfer of water molecules, and further form a hydration layer on the surface of the polyethersulfone membrane, effectively improving the anti-pollution performance of the RO membrane.

[0094] 3-Sulfopropyltetradecyl dimethyl betaine belongs to sulfobetaine, which can combine with more water molecules than hexane. At the same time, 3-Sulfopropyltetradecyl dimethyl betaine can also be co-deposited with polydopamine, thereby achieving a better connection effect between 3-Sulfopropyltetradecyl dimethyl betaine and polyethersulfone membrane.

[0095] Referring to Example 3 and Example 4 and combining with Table 3, it can be seen that relative to Example 3, the flux reduction rate of Example 4 is further reduced, which indicates that when 3-sulfopropyltetradecyl dimethyl betaine and hexanehexatin are used in combination, the prepared RO membrane will have better anti-pollution performance.

[0096] The reason is that, compared with selecting 3-sulfopropyl tetradecyl dimethyl betaine alone as a hydrophilic modifier, the simultaneous use of hexadecyl hexacol and 3-sulfopropyl tetradecyl dimethyl betaine will enable the polyethersulfone membrane to obtain better anti-fouling performance. The reason is that hexadecyl hexacol is connected to the surface of the polydopamine coating through external modification, while 3-sulfopropyl tetradecyl dimethyl betaine exists inside the polydopamine coating through co-deposition. Therefore, the two will have an internal and external synergistic effect, thereby enabling the RO membrane to obtain a better hydrophilic effect, which is ultimately manifested as a better anti-fouling performance.

[0097] With reference to Examples 4 to 6 and in combination with Table 3, it can be seen that, relative to Example 4, the flux reduction rates of Examples 5 to 6 are slightly improved, which indicates that when 3-sulfopropyltetradecyl dimethyl betaine is added in the amount of Example 4 and hexanexacol is added at the concentration of Example 4, the prepared RO membrane will have better anti-pollution performance.

[0098] Referring to Example 4 and Example 7 and combining with Table 3-4, it can be seen that the flux reduction rate of Example 7 is basically unchanged compared with Example 4, which shows that the addition of reversible acylhydrazone diol has little effect on the anti-fouling performance of the RO membrane.

[0099] However, compared with Example 1, the durability of Example 7 is significantly reduced, which shows that the addition of reversible acylhydrazone diol can effectively improve the service life of the RO membrane. The reason is that during the long-term use of the RO membrane, the micro-damage of the polydopamine coating is likely to cause further adhesion of pollutants, and the self-repair function of the polydopamine coating can effectively improve the above problems. Self-repair includes autonomous self-repair and non-autonomous self-repair, in which autonomous self-repair does not require any additional external triggers. The destruction itself is a stimulus for self-repair, and the repair process is carried out autonomously within the material structure. In order to promote the self-repair function of the polymer, non-covalent bonds such as hydrogen bonds, ionic interactions or metal-ligand interactions and reversible covalent bonds such as disulfide bonds or acylhydrazone bonds are usually introduced into the polymer.

[0100] In the present application, while adding hexane hexol, reversible acylhydrazone diol is also added, so that non-covalent hydrogen bonds and reversible covalent acylhydrazone bonds exist on the surface of the polydopamine coating at the same time, thereby promoting the hydrophilic modified material-polydopamine coating to have certain self-healing properties, thereby obtaining better durability.

[0101] Referring to Examples 7 to 9 and in combination with Table 4, it can be seen that, relative to Example 7, the durability of Examples 8 to 9 is slightly improved, which indicates that when the concentration ratio of hexanehexol and reversible acylhydrazone diol is used in Example 7, the prepared RO membrane will have better durability.

[0102] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A ro membrane filter element for a water purifier, characterized in that, The invention is a polyethersulfone membrane with a hydrophilic modifier-polydopamine coating deposited on the surface, wherein the hydrophilic modifier is one or more of polyethylene glycol, hexanehexacol and 3-sulfopropyl tetradecyl dimethyl betaine.

2. The RO membrane filter element for a water purifier according to claim 1, characterized in that: The hydrophilic modifier is 3-sulfopropyltetradecyl dimethyl betaine.

3. The RO membrane filter element for a water purifier according to claim 2, characterized in that: The deposition method of the hydrophilic modifier-polydopamine coating is: First, 3-sulfopropyltetradecyl dimethyl betaine is added to 50 ml of Tris buffer containing dopamine hydrochloride at a concentration of 1.8-2.2 mg / ml, and then the polyethersulfone membrane is immersed in the above solution. After reacting at room temperature for 3-5 hours, it is rinsed with deionized water and dried with nitrogen to obtain a polyethersulfone membrane with a hydrophilic modification-polydopamine coating deposited thereon.

4. The RO membrane filter element for a water purifier according to claim 1, characterized in that: The hydrophilic modified substances are hexane hexacol and 3-sulfopropyl tetradecyl dimethyl betaine.

5. The RO membrane filter element for a water purifier according to claim 4, characterized in that: The deposition method of the hydrophilic modifier-polydopamine coating comprises the following steps: S1. First, 3-sulfopropyl tetradecyl dimethyl betaine is added to 50 ml of a Tris buffer solution containing dopamine hydrochloride at a concentration of 1.8-2.2 mg / ml, and then a polyethersulfone membrane is immersed in the above solution. After reacting at room temperature for 3-5 hours, the membrane is rinsed with deionized water and dried with nitrogen gas to obtain a polyethersulfone membrane with a 3-sulfopropyl tetradecyl dimethyl betaine-polydopamine coating deposited thereon; S2. First, hexamethylenetetradecyl dimethyl betaine-polydopamine coating-deposited polyethersulfone membrane is dissolved in 1 wt% triethylamine aqueous solution, and then the polyethersulfone membrane with 3-sulfopropyltetradecyl dimethyl betaine-polydopamine coating is immersed in the hexamethylenetetradecyl dimethyl betaine-polydopamine aqueous solution for 20-40 minutes, and finally rinsed with deionized water and dried with nitrogen to obtain a polyethersulfone membrane with hydrophilic modifier-polydopamine coating deposition.

6. The RO membrane filter element for a water purifier according to claim 4, characterized in that: The addition amount of the 3-sulfopropyltetradecyl dimethyl betaine is 40-50 mg, and the concentration of the hexasol is 1-5 wt %.

7. The RO membrane filter element for a water purifier according to claim 4, characterized in that: In S2, a reversible acylhydrazone diol is added simultaneously with the addition of hexanediol.

8. The RO membrane filter element for a water purifier according to claim 7, characterized in that: The concentration ratio of the hexasol to the reversible acylhydrazone diol is (1-2): (1-2).

9. The RO membrane filter element for a water purifier according to claim 7, characterized in that: The preparation method of the reversible acylhydrazone diol is: 20-30g of p-hydroxybenzaldehyde is dissolved in 50-70ml of isopropanol, 15-20g of adipic acid dihydrazide is dissolved in 70-90ml of glacial acetic acid, and then the two are mixed evenly at a temperature of 60-80°C, and then filtered, washed with ethanol and deionized water in turn to remove impurities, and finally dried to obtain a reversible acylhydrazone diol.

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