Anti-pollution reverse osmosis membrane as well as preparation method and application thereof

Abstract

The invention relates to the field of anti-pollution reverse osmosis membrane materials, and discloses an anti-pollution reverse osmosis membrane as well as a preparation method and application thereof. The method for preparing the anti-pollution reverse osmosis membrane comprises the following steps: (1) carrying out first contact treatment on a porous support membrane and a water phase solution to obtain an intermediate I; (2) carrying out second contact treatment on the intermediate I and an oil phase solution to obtain a porous support membrane I with a polyamide separation layer; and (3) sequentially carrying out contact treatment on the porous support membrane I with a dopamine solution, a polyethyleneimine solution, a glycidyl solution and a polyvinyl alcohol solution to obtain the anti-pollution reverse osmosis membrane. According to the anti-pollution reverse osmosis membrane provided by the invention, the separation performance and the water yield of a basic reverse osmosis membrane are not changed, and meanwhile, the anti-pollution performance of the membrane can be improved.

Description

Technical Field

[0001] The present invention relates to the field of anti-pollution reverse osmosis membrane materials, and in particular to an anti-pollution reverse osmosis membrane and a preparation method and application thereof. Background Art

[0002] With increasing public awareness of water resources and the environment, coupled with the development of domestic membrane science, more and more domestically produced membrane modules are being used in industry. Due to the complex nature of raw water, pretreatment processes such as multi-media filters, activated carbon filtration, and flocculants are often required before the raw water enters the membrane module. These substances, combined with the complex water quality, enter the membrane module under pressure, inevitably leading to membrane fouling.

[0003] Membrane fouling reduces membrane water flux and salt rejection, two key performance indicators. To achieve ideal water yields, pressure applications and frequent chemical cleaning are often employed. These methods damage the membrane, shortening its service life while increasing costs and energy consumption. Statistics show that controlling membrane fouling accounts for 50% of the total operating cost of a membrane system.

[0004] Currently, methods for preparing anti-fouling reverse osmosis membranes primarily include adding additives to the water and oil phases (e.g., CN116036878A), surface modification (e.g., CN116351258A), and composite coatings (e.g., US6177011, CN105833743). However, these methods are complex and struggle to balance membrane selectivity and anti-fouling properties.

[0005] CN114768556A discloses a method for preparing a PDA-PEI modified membrane, comprising the following steps:

[0006] (1) DA is dissolved in a Tris-HCl buffer solution to prepare a DA-modified solution; a reverse osmosis membrane is placed in a reaction vessel, the DA-modified solution is poured in, and the reaction is carried out at room temperature. The DA-modified solution is then poured out, and the surface of the reverse osmosis membrane is repeatedly rinsed with deionized water to obtain a modified membrane with a PDA coating; (2) a PEI aqueous solution is poured into the reaction vessel, the reaction is carried out at 37°C, the PEI aqueous solution is poured out, and the surface of the reverse osmosis membrane is repeatedly rinsed with deionized water to obtain a PDA-PEI-modified reverse osmosis membrane. However, this method is difficult to balance the membrane water flux and desalination rate.

[0007] Therefore, there is still a lot of room for development in the existing anti-fouling reverse osmosis membrane development technology. It is necessary to provide a basic reverse osmosis membrane that has good separation performance, large flux and good anti-fouling performance. Summary of the Invention

[0008] The purpose of the present invention is to solve the problem in the prior art that the reverse osmosis membrane is difficult to have good anti-pollution performance, good separation performance and high flux at the same time.

[0009] In order to achieve the above object, the first aspect of the present invention provides a method for preparing an anti-fouling reverse osmosis membrane, the method comprising:

[0010] (1) subjecting a porous support membrane to a first contact treatment with an aqueous solution to obtain an intermediate I; the porous support membrane having a pore size of 70-100 nm;

[0011] (2) subjecting the intermediate I to a second contact treatment with an oil phase solution to obtain a porous support membrane I having a polyamide separation layer;

[0012] (3) contacting the porous support membrane I with a dopamine solution, a polyethyleneimine solution, a glycidol solution, and a polyvinyl alcohol solution in sequence to obtain an anti-pollution reverse osmosis membrane;

[0013] In step (3), the concentration of the dopamine solution is 0.1-0.5 wt%; the concentration of the polyethyleneimine solution is 0.1-0.25 wt%, and the pH value is 6-8; the concentration of the glycidol solution is 2-5 wt%; the concentration of the polyvinyl alcohol solution is 7-9 wt%; and

[0014] The contact treatment time with the glycidol solution is 20-50 minutes.

[0015] The second aspect of the present invention provides an anti-fouling reverse osmosis membrane prepared by the method described in the first aspect.

[0016] The third aspect of the present invention provides use of the anti-pollution reverse osmosis membrane described in the second aspect in sewage treatment.

[0017] Through the above technical solution, the present invention has at least the following advantages:

[0018] (1) The anti-pollution reverse osmosis membrane provided by the present invention can improve the anti-pollution performance of the membrane without changing the separation performance and water production of the basic reverse osmosis membrane.

[0019] (2) The anti-pollution reverse osmosis membrane provided by the present invention has lower surface roughness, higher surface hydrophilicity, and lower surface charge, which moves the isoelectric point of the membrane surface toward a higher pH value, thereby increasing the anti-pollution ability of the anti-pollution reverse osmosis membrane.

[0020] (3) The anti-pollution reverse osmosis membrane provided by the present invention can be applied to sewage treatment, especially sewage and urban sewage generated in the fields of electricity, steel, petrochemical, coal chemical industry, etc. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0022] In the present invention, the contact treatment surfaces of the "first contact treatment" in step (1), the "second contact treatment" in step (2), and the "contact treatment" in step (3) are all the surfaces of the polyester non-woven fabric of the porous support membrane on which the support layer material is present.

[0023] As mentioned above, the first aspect of the present invention provides a method for preparing an anti-fouling reverse osmosis membrane, the method comprising:

[0024] (1) subjecting a porous support membrane to a first contact treatment with an aqueous solution to obtain an intermediate I; the porous support membrane having a pore size of 70-100 nm;

[0025] (2) subjecting the intermediate I to a second contact treatment with an oil phase solution to obtain a porous support membrane I having a polyamide separation layer;

[0026] (3) contacting the porous support membrane I with a dopamine solution, a polyethyleneimine solution, a glycidol solution, and a polyvinyl alcohol solution in sequence to obtain an anti-pollution reverse osmosis membrane;

[0027] In step (3), the concentration of the dopamine solution is 0.1-0.5 wt%; the concentration of the polyethyleneimine solution is 0.1-0.25 wt%, and the pH value is 6-8; the concentration of the glycidol solution is 2-5 wt%; the concentration of the polyvinyl alcohol solution is 7-9 wt%; and

[0028] The contact treatment time with the glycidol solution is 20-50 minutes.

[0029] Preferably, the porous support membrane is a polysulfone ultrafiltration membrane.

[0030] Preferably, in step (1), the aqueous phase solution contains m-phenylenediamine and sodium dodecylbenzenesulfonate.

[0031] Preferably, in step (1), the pH value of the aqueous solution is 7-9, the concentration of the m-phenylenediamine is 1-8 wt %, and the concentration of the sodium dodecylbenzenesulfonate is 0.1-1 wt %.

[0032] Preferably, in step (1), the conditions of the first contact treatment include: temperature of 23-27° C., and time of 60-180 s.

[0033] According to a preferred embodiment, the method further comprises, in step (1), performing a first drying after the first contact treatment to obtain the intermediate I.

[0034] Preferably, the first drying conditions include: temperature of 40-80° C. and time of 60-120 seconds.

[0035] Preferably, in step (2), the oil phase solution contains trimesoyl chloride.

[0036] Preferably, in step (2), the solvent of the oil phase solution is isoparaffin solvent oil.

[0037] Preferably, in step (2), the pH value of the oil phase solution is 8-10, and the concentration of trimesoyl chloride is 0.1-1 wt %.

[0038] Preferably, in step (2), the conditions of the second contact treatment include: temperature of 35-55° C., and time of 60-120 s.

[0039] According to a preferred embodiment, the method further comprises, in step (2), performing a second drying after the second contact treatment to obtain the porous support membrane I.

[0040] Preferably, the second drying conditions include: a temperature of 70-120° C. and a time of 4-6 minutes.

[0041] Preferably, in step (3), the concentration of the dopamine solution is 0.2-0.3 wt%; the concentration of the polyethyleneimine solution is 0.1-0.15 wt%, and the pH value is 7-7.5; the concentration of the glycidol solution is 2.5-3.5 wt%; and the concentration of the polyvinyl alcohol solution is 8-8.5 wt%.

[0042] Preferably, in step (3), the number average molecular weight of the polyethyleneimine in the polyethyleneimine solution is 10,000 to 30,000.

[0043] Preferably, in step (3), the temperature for contact treatment with the dopamine solution is 23-27° C., and the time is 1-4 h.

[0044] More preferably, in step (3), the contact treatment time with the dopamine solution is 2-3 hours.

[0045] Preferably, in step (3), the temperature for contact treatment with the polyethyleneimine solution is 23-27° C., and the time is 20-60 min.

[0046] More preferably, in step (3), the contact treatment time with the polyethyleneimine solution is 20-40 minutes.

[0047] Preferably, in step (3), the temperature for contact treatment with the glycidol solution is 23-27° C., and the time is 30-40 min.

[0048] Preferably, the temperature for contact treatment with the polyvinyl alcohol solution is 23-27° C., and the time is 5-30 minutes.

[0049] According to a preferred embodiment, the method further includes, in step (3), contacting the porous support membrane I in a dopamine solution, a polyethyleneimine solution, a glycidol solution and a polyvinyl alcohol solution in sequence, and then performing a third drying to obtain an anti-pollution reverse osmosis membrane.

[0050] Preferably, the conditions for the third drying include: a temperature of 80-120° C. and a time of 1-5 minutes.

[0051] In order to obtain a reverse osmosis membrane with better anti-fouling performance, according to a particularly preferred embodiment, the method further comprises, in step (3), sequentially subjecting the porous support membrane I to contact treatment in a dopamine solution, a polyethyleneimine solution, a glycidol solution, and a polyvinyl alcohol solution, comprising:

[0052] (3-1) contacting the porous support membrane I in a dopamine solution and then rinsing it for the first time to obtain a porous support membrane II;

[0053] (3-2) contacting the porous support membrane II in a polyethyleneimine solution and then rinsing the porous support membrane II for the second time to obtain a porous support membrane III;

[0054] (3-3) contacting the porous support membrane III in a glycidol solution and then rinsing the porous support membrane for the third time to obtain a porous support membrane IV;

[0055] (3-4) The porous support membrane IV is subjected to contact treatment in a polyvinyl alcohol solution to obtain an anti-fouling reverse osmosis membrane.

[0056] Preferably, the conditions for the first rinsing include: a temperature of 23-27° C. and a time of 2-3 hours.

[0057] Preferably, the second rinsing conditions include: a temperature of 50-70° C. and a time of 60-180 seconds.

[0058] More preferably, the second rinsing conditions include: a temperature of 65-70°C.

[0059] Preferably, the conditions for the third rinsing include: a temperature of 23-27° C. and a time of 30-40 minutes.

[0060] According to a preferred embodiment, in step (3-2), the second rinsing is performed at least twice, and the total time of each rinsing is the time of the second rinsing.

[0061] It should be noted that the present invention has no specific requirements for the amount of solution used in the "first contact treatment" in step (1), the "second contact treatment" in step (2), and the "contact treatment" in step (3). It is only necessary to completely contact the surface of the polyester non-woven fabric of the porous support membrane with the support layer material with the solution.

[0062] As mentioned above, the second aspect of the present invention provides an anti-fouling reverse osmosis membrane prepared by the method described in the first aspect.

[0063] As mentioned above, the third aspect of the present invention provides the use of the anti-pollution reverse osmosis membrane described in the second aspect in sewage treatment.

[0064] The anti-pollution reverse osmosis membrane of the present invention can also be used to treat sewage and urban sewage generated in the fields of electricity, steel, petrochemicals, coal chemical industry, etc.

[0065] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials and instruments used are commercially available. The specific sources of the raw materials are shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] The references for the preparation of the porous support membrane I and the porous support membrane II in the present invention are: Ding Ying, Wu Yulin, Wu Jinglei, et al. Preparation and modification research of polysulfone flat ultrafiltration membrane [J]. Journal of Nanjing Xiaozhuang University, 2022, 38(06): 33-38.

[0070] Example 1

[0071] (1) subjecting the porous support membrane to a first contact treatment in an aqueous solution and then to a first drying step to obtain an intermediate I;

[0072] (2) The intermediate I is subjected to a second contact treatment in an oil phase solution and then subjected to a second drying to obtain a porous support membrane I having a polyamide separation layer; the solvent of the oil phase solution is isoparaffin solvent oil.

[0073] (3) subjecting the porous support membrane I to a contact treatment in a dopamine solution and then performing a first rinsing to obtain a porous support membrane II;

[0074] (4) The porous support membrane II was contact-treated in a polyethyleneimine solution and then rinsed for the second time (the number of rinses was 2, and the time and temperature of each rinse were the same, see Table 3) to obtain a porous support membrane III;

[0075] (5) contacting the porous support membrane III in a glycidol solution and then rinsing the porous support membrane for the third time to obtain a porous support membrane IV;

[0076] (6) The porous support membrane IV is subjected to a contact treatment in a polyvinyl alcohol solution and then subjected to a third drying process to obtain an anti-fouling reverse osmosis membrane.

[0077] Unless otherwise specified, the remaining examples were carried out with reference to the method of Example 1, except that the types of solutions, concentrations and process parameters used in each example were different. For specific types and concentrations of solutions, see Table 2; for specific process parameters, see Table 3.

[0078] Table 2

[0079]

[0080] Table 3

[0081]

[0082]

[0083] Example 6

[0084] Example 6 was carried out according to the method of Example 1, except that, while keeping the volume of the polyethyleneimine solution in step (4) of this example unchanged, the amount of polyethyleneimine was adjusted so that the concentration of the polyethyleneimine solution was 0.2 wt%.

[0085] Example 7

[0086] Example 7 was carried out in accordance with the method of Example 1, except that, while keeping the volume of the glycidol solution in step (5) of this example unchanged, the amount of glycidol was adjusted so that the concentration of the glycidol solution was 4 wt %.

[0087] Example 8

[0088] Example 8 was carried out according to the method of Example 1, except that polyethyleneimine I in step (4) of Example 8 was replaced by polyethyleneimine II of equal weight, and the rest was the same as in Example 1.

[0089] Comparative Example 1

[0090] Comparative Example 1 was carried out in accordance with the method of Example 1, except that the time for contact treatment with the glycidol solution in step (5) of Comparative Example 1 was adjusted to 60 min.

[0091] Comparative Example 2

[0092] Step (1), step (2), step (3) and step (4) are the same as in Example 1.

[0093] Step (5): The porous support membrane III obtained in step (4) is subjected to a contact treatment in a polyvinyl alcohol solution and then subjected to a third drying to obtain an anti-pollution reverse osmosis membrane; the conditions of the contact treatment and the third drying are the same as those in Example 1.

[0094] Comparative Example 3

[0095] Comparative Example 3 was carried out in accordance with the method of Example 1, except that, while keeping the volume of the glycidol solution in step (5) of this comparative example unchanged, the amount of glycidol was adjusted so that the concentration of the glycidol solution was 5.5 wt %.

[0096] Comparative Example 4

[0097] Comparative Example 4 was carried out with the same method as Example 1, except that the porous support membrane I in Example 1 was replaced with a porous support membrane II of the same size.

[0098] Test Case

[0099] The anti-fouling reverse osmosis membrane prepared in the example was subjected to the following tests, and the test results are shown in Table 4.

[0100] (1) Membrane desalination rate and water flux: measured according to the method specified in GB / T 32373-2015. The specific test conditions are: test temperature 25±0.5℃, pH 7.5±0.5.

[0101] (2) Contact angle: The test method is GB / T 30693-2014.

[0102] (3) Zeta potential: The test method is GB / T 37617-2019. The specific test conditions are: measurement at a pH value of 7.

[0103] (4) X-ray photoelectron spectroscopy: the test method is GB / T 19500-2004.

[0104] (5) CTAB anti-fouling test experiment: (a) Test the initial permeation flux of the membrane. The raw liquid is 2000±20 mg / L sodium chloride solution, the pressure is 1.55 MPa, and the system cross-flow flow rate is 0.45 m / s. (b) When the membrane permeation flux is stable, the raw liquid is replaced with a pre-configured CTAB solution (containing 50 mg / L CTAB and 2000±20 mg / L sodium chloride). The pH value of the raw liquid is 7.5±0.5. The raw liquid temperature is always maintained at 25±0.5℃ by the constant temperature system. The membrane permeation flux change is recorded every hour. The membrane fouling experiment runs for 7 hours. (c) After the run is completed, the membrane surface is rinsed with pure water for 2 hours. After rinsing, the raw liquid is replaced with 2000±20 mg / L sodium chloride solution, and the membrane permeation flux is retested under the experimental conditions of a pressure of 1.55 MPa and a system cross-flow flow rate of 0.45 m / s to analyze the recovery of the membrane permeation flux.

[0105] Table 4

[0106]

[0107] Table 4

[0108]

[0109]

[0110] The results in Table 4 indicate that the anti-fouling reverse osmosis membrane obtained using the method of the present invention simultaneously exhibits excellent anti-fouling performance, good separation performance, and high flux. Furthermore, the anti-fouling reverse osmosis membrane provided by the present invention improves surface hydrophilicity, reduces surface negative charge, shifts the isoelectric point of the membrane surface toward a higher pH, and enhances the anti-fouling capability of the reverse osmosis membrane without changing the water flux and salt rejection rate of the basic reverse osmosis membrane.

[0111] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing an anti-pollution reverse osmosis membrane, characterized in that: The method includes: (1) subjecting a porous support membrane to a first contact treatment with an aqueous solution to obtain an intermediate I; the porous support membrane having a pore size of 70-100 nm; (2) subjecting the intermediate I to a second contact treatment with an oil phase solution to obtain a porous support membrane I having a polyamide separation layer; (3) contacting the porous support membrane I with a dopamine solution, a polyethyleneimine solution, a glycidol solution, and a polyvinyl alcohol solution in sequence to obtain an anti-pollution reverse osmosis membrane; In step (3), the concentration of the dopamine solution is 0.1-0.5 wt%; the concentration of the polyethyleneimine solution is 0.1-0.25 wt%, and the pH value is 6-8; the concentration of the glycidol solution is 2-5 wt%; the concentration of the polyvinyl alcohol solution is 7-9 wt%; and The contact treatment time with the glycidol solution is 20-50 minutes.

2. The method according to claim 1, wherein In step (1), the porous support membrane is a polysulfone ultrafiltration membrane.

3. The method according to claim 1 or 2, wherein: In step (1), the aqueous solution contains m-phenylenediamine and sodium dodecylbenzenesulfonate; And / or, in step (2), the oil phase solution contains trimesoyl chloride.

4. The method according to claim 3, wherein: In step (1), the pH value of the aqueous solution is 7-9, the concentration of m-phenylenediamine is 1-8 wt %, and the concentration of sodium dodecylbenzenesulfonate is 0.1-1 wt %; And / or, in step (2), the pH value of the oil phase solution is 8-10, and the concentration of trimesoyl chloride is 0.1-1 wt %.

5. The method according to any one of claims 1 to 4, wherein: In step (3), the concentration of the dopamine solution is 0.2-0.3 wt%; the concentration of the polyethyleneimine solution is 0.1-0.15 wt%, and the pH value is 7-7.5; the concentration of the glycidol solution is 2.5-3.5 wt%; and the concentration of the polyvinyl alcohol solution is 8-8.5 wt%.

6. The method according to any one of claims 1 to 5, wherein: In step (3), the temperature for contact treatment with the dopamine solution is 23-27° C. and the time is 1-4 hours; and / or, in step (3), the temperature for contact treatment with the polyethyleneimine solution is 23-27° C. and the time is 20-60 min; And / or, in step (3), the temperature for contact treatment with the glycidol solution is 23-27° C. and the time is 30-40 min.

7. The method according to any one of claims 1 to 6, wherein: The method further comprises, in step (3), sequentially contacting the porous support membrane I with a dopamine solution, a polyethyleneimine solution, a glycidol solution, and a polyvinyl alcohol solution, wherein: (3-1) contacting the porous support membrane I in a dopamine solution and then rinsing it for the first time to obtain a porous support membrane II; (3-2) contacting the porous support membrane II in a polyethyleneimine solution and then rinsing the porous support membrane II for the second time to obtain a porous support membrane III; (3-3) contacting the porous support membrane III in a glycidol solution and then rinsing the porous support membrane for the third time to obtain a porous support membrane IV; (3-4) contacting the porous support membrane IV in a polyvinyl alcohol solution to obtain an anti-fouling reverse osmosis membrane; And / or, the first rinsing conditions include: temperature of 23-27°C, time of 2-3h; And / or, the second rinsing conditions include: temperature of 50-70°C and time of 60-180s; And / or, the conditions of the third rinsing include: a temperature of 23-27° C. and a time of 30-40 minutes.

8. The method according to any one of claims 1 to 7, wherein: In step (3), the number average molecular weight of the polyethyleneimine in the polyethyleneimine solution is 10,000 to 30,000.

9. An anti-fouling reverse osmosis membrane prepared by the method according to any one of claims 1 to 8.

10. Use of the anti-pollution reverse osmosis membrane according to claim 9 in sewage treatment.

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