Reverse osmosis membrane with bionic aquatic plant anti-pollution antibacterial coating and preparation method of reverse osmosis membrane

Abstract

The invention belongs to the technical field of environmental protection, and particularly relates to a reverse osmosis membrane with a bionic aquatic plant anti-pollution antibacterial coating and a preparation method of the reverse osmosis membrane. A thiol-polyethylene glycol-amino compound surface functionalized nano antibacterial particle suspension is obtained; (2) adding an epoxy compound into the suspension to obtain a coating solution; and (3) applying the coating liquid to the surface of a reverse osmosis membrane, and drying to obtain the reverse osmosis membrane with the epoxy compound cross-linked nano antibacterial particle coating. The epoxy compound and the nano antibacterial particles are subjected to a cross-linking reaction to form a non-water-soluble polymer, and the non-water-soluble polymer is deposited on the surface of the reverse osmosis membrane and has excellent stability; ions released by the nano antibacterial particles have a sterilizing effect; the adsorption of cationic pollutants is effectively slowed down; the epoxy compound crosslinked on the surface of the nano particles has a bionic aquatic plant structure, and is beneficial to improving the anti-pollution performance of the reverse osmosis membrane.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating and a preparation method thereof. Background Art

[0002] Membrane separation technology has the functions of separation, concentration, purification and refining, and has the characteristics of high efficiency, energy saving, environmental protection and easy control. It has been widely used in food, medicine and other fields, generating huge economic and social benefits, and has become one of the most important means in today's separation science.

[0003] Reverse osmosis technology is a technology that separates substances by driving a membrane through pressure. Based on the selective permeability of the reverse osmosis membrane, which can only pass water molecules and intercept ions or small molecules, the pressure difference on both sides of the membrane is used as the driving force to achieve the effect of separating the mixture. In the actual operation of the reverse osmosis membrane, due to the complexity of water quality and the variability of the environment, a layer of pollutants is easily attached to its surface, which greatly reduces the separation effect of the reverse osmosis membrane.

[0004] Defects and shortcomings of the existing technology:

[0005] In order to reduce membrane pollution, the surface of the polyamide desalination layer of the reverse osmosis membrane is generally hydrophilically modified during the production process to reduce the hydrophobic properties of the membrane surface and reduce the pollution of some substances. The existing production process usually uses water-soluble polymers, such as polyvinyl alcohol (PVA) to directly hydrophilically modify the surface of the reverse osmosis membrane. Due to its good water solubility, polyvinyl alcohol is unstable on the surface of the reverse osmosis polyamide and is easy to fall off. The polyvinyl alcohol coating cannot achieve an antibacterial effect. The membrane product is prone to contamination by microorganisms and bacteria during operation, resulting in irreversible fouling of the membrane product and a serious reduction in the service life. Therefore, the preparation of a stable and antibacterial anti-pollution coating on the surface of the reverse osmosis membrane has an important impact on its use. Summary of the invention

[0006] In order to solve the defects of the prior art that the hydrophilic modification of the surface of the reverse osmosis membrane using polyvinyl alcohol is unstable and easy to fall off, the present invention provides a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating and a preparation method thereof.

[0007] The technical solution adopted by the present invention is as follows: A method for preparing a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating, comprising:

[0008] (1) adding a thiol-polyethylene glycol-amino compound to a nano-antibacterial particle dispersion to react and obtain a thiol-polyethylene glycol-amino compound surface functionalized nano-antibacterial particle suspension;

[0009] (2) adding an epoxy compound to the above suspension to obtain a coating solution;

[0010] (3) The coating liquid is applied to the surface of the reverse osmosis membrane, and after drying, a reverse osmosis membrane having an epoxy compound cross-linked nano antibacterial particle coating is obtained.

[0011] Furthermore, in some embodiments, the antibacterial nanoparticles are metal or metal oxide nanoparticles with antibacterial function.

[0012] Specifically, the antibacterial nanoparticles include one or more of nano-gold, nano-silver, nano-zinc, nano-zinc oxide, nano-copper or nano-copper oxide.

[0013] Specifically, the nano antibacterial particle dispersion is prepared by dispersing the antibacterial nanoparticles in toluene. Preferably, the mass volume ratio of the antibacterial nanoparticles to the dispersion is 0.5 mg / mL.

[0014] In some embodiments, the thiol-polyethylene glycol-amino compound includes thiol-polyethylene glycol 1000-amino, thiol-polyethylene glycol 2000-amino, thiol-polyethylene glycol 5000-amino, thiol-polyethylene glycol 10000-amino, thiol-polyethylene glycol 15000-amino, and thiol-polyethylene glycol 20000-amino.

[0015] Preferably, the mass ratio of the nanoparticles to the thiol-polyethylene glycol-amino compound is 1:4.

[0016] Preferably, the epoxy compound includes diepoxybutane, diethylene glycol diglycidyl ether, methacrylate glycidyl ether, polyethylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol glycidyl ether, polypropylene glycol glycidyl ether, resorcinol diglycidyl ether, and butanediol glycidyl ether.

[0017] Preferably, the mass ratio of the mercapto-polyethylene glycol-amino compound to the epoxy compound is 1.5:1.

[0018] Preferably, step (3) is to uniformly apply the coating liquid to the surface of the reverse osmosis membrane, let it stand for 60 seconds, pour off the excess coating liquid on the surface, and then put the membrane into an oven at 80°C for drying.

[0019] The present invention also provides a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating, which is prepared by the above method.

[0020] Beneficial effects: Epoxy compounds and nano antibacterial particles form water-insoluble polymers through cross-linking reaction, which are deposited on the surface of reverse osmosis membranes and have excellent stability. In a flowing water environment, they can remain stable and will not fall off;

[0021] The ions released by the nano antibacterial particles have a bactericidal effect, and the composite coating gives the reverse osmosis membrane antibacterial properties;

[0022] The unique thiol-polyethylene glycol-amino compound crosslinker has an amino group and is positively charged, which effectively repels cationic pollutants and slows down the adsorption of cationic pollutants during use;

[0023] The epoxy compounds cross-linked on the surface of the nanoparticles have a bionic water grass structure. The existing molecular chains can form molecular brushes in the water environment, which can effectively reduce the deposition of pollutants and help improve the anti-pollution performance of the reverse osmosis membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The flowchart of the preparation process of the reverse osmosis membrane with the bionic aquatic grass anti-pollution and antibacterial coating of the present invention;

[0025] Figure 2 The SEM images of the reverse osmosis membrane prepared in Comparative Example 1 before and after alkali treatment;

[0026] Figure 3 The SEM images of the reverse osmosis membrane prepared in Example 1 before and after alkali treatment;

[0027] Figure 4 This is a diagram showing the antibacterial effects of the reverse osmosis membranes prepared in Comparative Example 1 and Example 1. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with specific implementation methods. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative changes belong to the protection scope of the present invention.

[0029] Comparative Example 1:

[0030] Dissolve 1.0 g of polyvinyl alcohol in 100 mL of water and mix well to prepare a 1% polyvinyl alcohol coating solution for later use;

[0031] The coating liquid in step 1 is evenly coated on the surface of the brackish water reverse osmosis membrane of Entai Technology, left to stand for 60 seconds, the excess solution on the surface of the membrane is poured off, and dried in an oven at 80°C to obtain a reverse osmosis membrane with a polyvinyl alcohol coating, which is comparison sample 1.

[0032] like Figure 1 As shown, the preparation process of the reverse osmosis membrane with bionic aquatic grass anti-pollution and antibacterial coating of the present invention is as follows: the surface of antibacterial nanoparticles is modified by surface functionalization using thiol-polyethylene glycol-amino compounds, and then cross-linked with epoxy compounds, and then deposited on the reverse osmosis membrane.

[0033] Example 1

[0034] (1) ultrasonically dispersing 0.05 g of silver nanoparticles in 100 ml of toluene solution, adding 0.3 g of thiol-polyethylene glycol 1000-amino compound, stirring at 90° C. for 2 h, and obtaining a thiol-polyethylene glycol 1000-amino surface functionalized nano antibacterial particle suspension solution for later use;

[0035] (2) adding 0.2 g of polyethylene glycol diglycidyl ether compound solution to the thiol-polyethylene glycol 1000-amino surface functionalized nano antibacterial particle suspension solution, stirring and mixing evenly to obtain a coating solution for later use;

[0036] (3) The coating solution mixed in step 2 was evenly applied to the surface of the brackish water reverse osmosis membrane of Entai Technology, left to stand for 60 seconds, and the excess solution on the surface was poured off;

[0037] (4) The membrane sheet was placed in an oven at 80° C. for drying to obtain a reverse osmosis membrane having a polyethylene glycol diglycidyl ether cross-linked nanosilver particle coating.

[0038] Example 2

[0039] The nano-silver particles in step (1) of Example 1 were replaced with nano-zinc particles, and the other steps and raw materials remained unchanged, to prepare a reverse osmosis membrane having a coating of polyethylene glycol diglycidyl ether cross-linked nano-zinc particles.

[0040] Example 3

[0041] The mercapto-polyethylene glycol 1000-amino group in step (1) of Example 1 was replaced with mercapto-polyethylene glycol 5000-amino group, and the other steps and raw materials remained unchanged to obtain a reverse osmosis membrane with an anti-fouling and antibacterial coating;

[0042] Example 4

[0043] The polyethylene glycol diglycidyl ether compound in step (2) of Example 1 was replaced with butanediol glycidyl ether, and the other steps and raw materials remained unchanged to prepare a reverse osmosis membrane having a butanediol glycidyl ether cross-linked nanosilver particle coating.

[0044] Performance Testing

[0045] The reverse osmosis membranes modified from the above embodiments and comparative examples were subjected to relevant performance tests, including anti-pollution performance test, coating stability test, and antibacterial performance test.

[0046] a. Water treatment performance test conditions: According to the test platform required by the national standard GB / T 32373-2015, add 10ppm hexadecyltrimethylammonium bromide and 100ppm bovine serum albumin to the 2000ppm NaCl solution, mix well and use as the test solution for standby; under the test conditions of 225psi operating pressure, temperature 25±1℃, pH value 7.0±0.5, test the water production (m0) and desalination rate of the membrane, and then test the water production (m1) of the membrane after continuous operation for 24 hours; then use hydrochloric acid solution (pH=1) and sodium hydroxide solution (pH=13) in turn to rinse the membrane, and then test the water production (m2) of the membrane. The membrane's anti-fouling performance is investigated by calculating the flux loss rate and flux recovery rate. The less the flux attenuation after operation, the better the anti-fouling performance. Flux loss rate = (1-m1 / m0)×100%, flux recovery rate = m2 / m0×100%. The results are shown in Table 1.

[0047] Table 1 Water treatment performance of the reverse osmosis membrane modified in the examples and comparative examples

[0048]

[0049] Table 2 Zeta potential data of reverse osmosis membranes obtained by modification of the embodiments and comparative examples

[0050]

[0051] According to the data analysis in Table 1, the initial water flux of the reverse osmosis membrane of the traditional polyvinyl alcohol coating (Comparative Example 1) is 42.89LMH, which is slightly higher than the anti-pollution and antibacterial reverse osmosis membrane prepared by this patent; after 24 hours of continuous pollution test, the water flux of the polyvinyl alcohol coating reverse osmosis membrane (Comparative Example 1) decayed to 30.99LMH, and the water flux of the membrane decayed by 27.75% compared with the initial data; after the anti-pollution and antibacterial reverse osmosis membrane prepared by this patent was polluted, the flux attenuation rate was below 7.5%, which shows that the anti-pollution and antibacterial reverse osmosis prepared by this patent has excellent anti-pollution performance; the excellent anti-pollution performance is the bionic water grass structure of the epoxy compound, which can form a layer of molecular brushes on the surface of the membrane, effectively slowing down the deposition of pollutants; at the same time, the unique thiol-polyethylene glycol-amino compound cross-linking agent has an amino group, and the surface of the modified reverse osmosis membrane has a slight positive charge (Table 2 data), which effectively repels hexadecyltrimethylammonium bromide pollutants during use and slows down the adsorption of hexadecyltrimethylammonium bromide pollutants.

[0052] The flux loss rate of each case membrane after 12 hours of operation and the flux recovery rate after cleaning were compared in depth; after chemical cleaning, the water flux of the traditional polyvinyl alcohol coated reverse osmosis membrane recovered to 38.66LMH. Compared with the initial flux data, the flux recovery rate after cleaning was 90.14%; the anti-pollution and antibacterial reverse osmosis prepared by this patent maintained a water flux recovery rate of more than 97% after chemical cleaning. The bionic water grass structure of the epoxy compound slowed down the deposition of pollutants while effectively blocking the adsorption of pollutants to the polyamide layer. The pollutants were only deposited on the surface of the molecular brush. The pollutants can be efficiently washed away during chemical cleaning, so that the membrane exhibits excellent water flux cleaning recovery.

[0053] Investigation on the stability of anti-pollution coating

[0054] The reverse osmosis membranes prepared in Comparative Example 1 and Example 1 were immersed in a 4% sodium hydroxide solution for 150 hours, and the microstructure of the membrane surface coating before and after the alkali solution treatment was observed to determine the coating stability; Figure 2 As shown in the figure, there is an obvious layer of polyvinyl alcohol on the membrane surface before alkali soaking, but after alkali soaking, the polyvinyl alcohol coating falls off, and the membrane surface shows a typical "peak and valley" polyamide layer structure, and the polyvinyl alcohol coating has poor stability; Figure 3 As shown, after the polyethylene glycol diglycidyl ether cross-linked nanosilver particle coating reverse osmosis membrane prepared by the present invention is soaked in alkali solution, the typical "peak and valley" polyamide layer structure does not appear on the surface of the membrane, and the microscopic morphology of the membrane before and after alkali soaking is basically the same. This shows that the polyethylene glycol diglycidyl ether cross-linked nanosilver particle coating prepared by the present invention has excellent stability and meets the cleaning requirements of the reverse osmosis product during use.

[0055] Antibacterial performance investigation

[0056] The antibacterial performance test was carried out with reference to the film sticking method in the national standard GB21551.2-2010; the reverse osmosis membranes prepared in comparative example 1 and example 1 were cut into samples of 50 mm*50 mm and placed in sterilized dishes; 0.2 mL of the test Escherichia coli suspension was respectively added dropwise to the test sample and the control sample; after culturing for 24±1 h at 37±1°C and relative humidity RH>90%, the samples were taken out, 20 mL of the eluent was added respectively, the test sample and the control sample were repeatedly washed, and after being fully shaken, the eluent was gradiently diluted and inoculated into the nutrient agar medium (NA), and the live bacteria were counted after culturing at 37±1°C for 24h-48h, and the number of live bacteria in the eluent was determined to judge the antibacterial performance of the membrane.

[0057] according to Figure 4The phenomenon in the figure shows that compared with the surface cleaning liquid of the reverse osmosis membrane with polyvinyl alcohol coating (Comparative Example 1), the number of colonies in the surface flushing liquid of the reverse osmosis membrane with polyethylene glycol diglycidyl ether cross-linked nanosilver particles coating (Example 1) is significantly less, which clearly shows that the reverse osmosis membrane with polyethylene glycol diglycidyl ether cross-linked nanosilver particles coating has excellent antibacterial properties. This is because the nanosilver particles will slowly release silver ions, which will destroy the cell structure of microorganisms such as bacteria, thereby playing a bactericidal role.

[0058] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of this application.

Claims

1. A method for preparing a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating, characterized in that: The method comprises: (1) adding a thiol-polyethylene glycol-amino compound to a nano antibacterial particle dispersion to react and obtain a thiol-polyethylene glycol-amino compound surface functionalized nano antibacterial particle suspension; (2) adding an epoxy compound to the above suspension to obtain a coating solution; (3) The coating liquid is applied to the surface of the reverse osmosis membrane, and after drying, a reverse osmosis membrane having an epoxy compound cross-linked nano antibacterial particle coating is obtained.

2. The method for preparing a reverse osmosis membrane having a bionic aquatic plant anti-pollution and antibacterial coating according to claim 1, characterized in that: The antibacterial nanoparticles are metal or metal oxide nanoparticles with antibacterial function.

3. The method for preparing a reverse osmosis membrane having a bionic aquatic plant anti-pollution and antibacterial coating according to claim 1 or 2, characterized in that: The nano antibacterial particles include one or more of nano gold, nano silver, nano zinc, nano zinc oxide, nano copper or nano copper oxide.

4. The method for preparing a reverse osmosis membrane having a bionic aquatic plant anti-pollution and antibacterial coating according to claim 1 or 2, characterized in that: The nano antibacterial particle dispersion is prepared by dispersing antibacterial nano particles in toluene.

5. The method for preparing a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating according to claim 1 or 2, characterized in that: The thiol-polyethylene glycol-amino compound includes thiol-polyethylene glycol 1000-amino, thiol-polyethylene glycol 2000-amino, thiol-polyethylene glycol 5000-amino, thiol-polyethylene glycol 10000-amino, thiol-polyethylene glycol 15000-amino and thiol-polyethylene glycol 20000-amino.

6. The method for preparing a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating according to claim 5, characterized in that: The mass ratio of the nanoparticles to the thiol-polyethylene glycol-amino compound is 1:

4.

7. The method for preparing a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating according to claim 1, characterized in that: The epoxy compounds include diepoxybutane, diethylene glycol diglycidyl ether, methacrylate glycidyl ether, polyethylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol glycidyl ether, polypropylene glycol glycidyl ether, resorcinol diglycidyl ether, and butanediol glycidyl ether.

8. The method for preparing a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating according to claim 1 or 7, characterized in that: The mass ratio of the mercapto-polyethylene glycol-amino compound to the epoxy compound is 1.5:

1.

9. The method for preparing a reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating according to claim 1, characterized in that: Step (3) specifically comprises the following steps: uniformly coating the coating liquid on the surface of the reverse osmosis membrane, allowing it to stand for 60 seconds, pouring off the excess coating liquid on the surface, and then placing the membrane in an oven at 80° C. for drying.

10. A reverse osmosis membrane with a bionic aquatic plant anti-pollution and antibacterial coating, characterized in that: It is prepared according to the method according to any one of claims 1 to 9.

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