Antibacterial and antifouling ultrafiltration membrane and preparation method thereof

Abstract

The invention belongs to the technical field of ultrafiltration membrane preparation, and particularly relates to an antibacterial and antifouling ultrafiltration membrane and a preparation method thereof. The preparation method comprises the following steps: synthesizing a terpolymer from 2, 2 '-allyl bisphenol A, 4, 4'-dichlorodiphenyl sulfone and diphenylsulfonyl-4, 4 '-dichloro-3, 3'-disodium disulfonate, introducing allylcatechol to the polymer through an in-situ grafting method, preparing an ultrafiltration membrane through a non-solvent induced phase separation method, carrying out alkali treatment, and separating the ultrafiltration membrane to obtain the high-purity allylcatechol / 2, 4 '-dichlorodiphenyl sulfone / 2, 2'-allyl bisphenol A / 2, 4 '-dichlorodiphenyl sulfone / 2, 2'-dichlorodiphenyl sulfone / 2, 4 '-dichloro-3, 3'-disodium disulfonate. The antibacterial peptide is fixed on the surface of the polymer membrane through a reaction between-NH2 in the antibacterial peptide and a catechol group, so that the ultrafiltration membrane has excellent antibacterial, anti-pollution and hydrophilic properties.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrafiltration membrane preparation, and specifically relates to an antibacterial and antifouling ultrafiltration membrane and a preparation method thereof. Background Art

[0002] Ultrafiltration membranes have gradually entered daily life and become an effective measure for initial water treatment due to their environmental friendliness, low price, and easy operation of developed equipment. Ultrafiltration (UF) technology is a membrane separation technology between microfiltration and nanofiltration, with an average pore size of 3 to 100 nm, and has the functions of purifying, separating, and concentrating solutions. Its interception mechanism mainly includes the screening effect and electrostatic effect of the membrane. The filter medium is an ultrafiltration membrane. Driven by the pressure difference on both sides, only low molecular weight solutes and water can pass through the ultrafiltration membrane, thereby achieving the purpose of purification, separation, and concentration. Since the common materials for preparing ultrafiltration membranes are basically hydrophobic materials, membrane contamination frequently occurs during the use of ultrafiltration membranes.

[0003] Membrane fouling refers to the phenomenon that during the use of ultrafiltration membrane, particles, colloidal particles, solute macromolecules or microorganisms in water are adsorbed and deposited on the membrane surface or in the membrane pores due to physical and chemical interactions or mechanical effects with the membrane, causing the membrane pore size to become smaller or blocked, and causing irreversible changes in the membrane's permeability and separation characteristics. Bacteria, fungi and other microorganisms can directly (through enzyme action) or indirectly (through local pH or reduction potential) degrade polymer membranes or membrane elements, resulting in shortened membrane life and damaged membrane structural integrity. At present, the main ways to alleviate membrane fouling are pretreatment of raw water, membrane cleaning and membrane modification.

[0004] Pre-treatment of raw water and membrane cleaning can reduce the degree of membrane pollution to a certain extent, but it not only cannot fundamentally solve the problem of membrane pollution, but also reduces the efficiency of production operations, increases costs, and reduces the service life of the membrane. At the same time, most of the current research on membrane modification is basically to enhance the hydrophilicity of the membrane surface. Among them, blending modification is the most common and most studied method. Nanoparticles, organic matter or polymers are directly added to the membrane material by physical blending to modify the membrane, but its disadvantage is that the compatibility and dispersibility of the particles and materials will have a direct impact on the performance of the membrane. In addition, there are methods such as surface grafting modification and post-treatment modification of the membrane, but the grafting rate and grafting stability of the surface grafting are difficult to control, and post-treatment modification has a series of problems such as unclear effect, low efficiency and instability. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides an antibacterial and antifouling ultrafiltration membrane and a preparation method thereof.

[0006] This is achieved specifically through the following technical solutions:

[0007] A method for preparing an antibacterial and antifouling ultrafiltration membrane comprises the following steps:

[0008] (1) Add 2,2'-allyl bisphenol A, 4,4'-dichlorodiphenyl sulfone, disodium diphenyl sulfone-4,4'-dichloro-3,3'-disulfonate, K2CO3, toluene and N-methylpyrrolidone into a flask, stir evenly at room temperature, then heat to 140-155°C and keep warm for 2-4 hours, then heat to 180-190°C and keep warm for 6-8 hours. After the reaction is completed, wash the obtained copolymer with pure water and anhydrous ethanol for 3-5 times respectively to obtain a terpolymer;

[0009] (2) The terpolymer, polysulfone or polyethersulfone, allyl o-diphenol, initiator and solvent are mixed uniformly, heated to 80-100° C. and stirred for 6-12 hours, and then vacuum degassed at a negative pressure of 0.3-0.5 MPa for 4-6 hours to obtain an in-situ grafted casting solution;

[0010] (3) using non-woven fabric as a support material, reacting the in-situ grafted casting solution with pure water by a non-solvent phase separation method, washing with hot water to form an ultrafiltration membrane, and soaking the ultrafiltration membrane in a NaOH solution for 24-48 hours;

[0011] (4) The antimicrobial peptide and pure water are stirred evenly to obtain an antimicrobial peptide solution, and then the ultrafiltration membrane obtained in step (3) is immersed in the antimicrobial peptide solution at room temperature for 6-10 hours, and then washed with pure water for 3-5 times, and finally immersed in 10-20wt% glycerol for treatment and then blown dry to obtain an antimicrobial and antifouling ultrafiltration membrane.

[0012] In step (1), the ratio of 2,2'-allyl bisphenol A, 4,4'-dichlorodiphenyl sulfone, disodium diphenyl sulfone-4,4'-dichloro-3,3'-disulfonate, K2CO3, toluene and N-methylpyrrolidone is 8-15:4-7.5:4-7.5:3-10:20-27:40-54.

[0013] In step (2), the ratio of the terpolymer, polysulfone or polyethersulfone, allyl o-diphenol, initiator and solvent is 7-9:7-9:7-9:0.5-1.0:72-78.5.

[0014] In step (2), the initiator is any one or more of azobisisobutyronitrile, dicumyl peroxide, and benzoyl peroxide; and the solvent is any one or more of N,N-dimethylformamide, Isopar G, N-methylpyrrolidone, and dimethylacetamide.

[0015] In step (3), the thickness of the non-woven fabric is 3.2-3.6 mil; the total thickness of the ultrafiltration membrane is 5.8-6.5 mil.

[0016] In step (3), the process conditions of the non-solvent phase separation method are: phase inversion time is 0.5-1 min, and the phase inversion water bath temperature is 12-25°C.

[0017] In step (3), the temperature of the hot water is 60-75°C.

[0018] In step (3), the concentration of the NaOH solution is 10-20 g / L.

[0019] The present invention also provides an antibacterial and antifouling ultrafiltration membrane prepared by the method for preparing the antibacterial and antifouling ultrafiltration membrane.

[0020] Beneficial effects:

[0021] The present invention introduces a large number of sulfonic acid groups into the substrate to improve the hydrophilicity of the ultrafiltration membrane, and then modifies the double bond structure introduced into the substrate so that the surface of the membrane material is evenly covered with antibacterial functional groups, thereby improving the structural stability and antibacterial and antifouling properties of the ultrafiltration membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : Comparison chart of BSA cycle pollution experiment;

[0023] Figure 2 : E. coli inhibition performance comparison chart;

[0024] Figure 3 : Comparison of Staphylococcus aureus inhibition performance. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments, and any improvement or substitution based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0026] Example 1

[0027] A method for preparing an antibacterial and antifouling ultrafiltration membrane comprises the following steps:

[0028] (1) 2,2'-allyl bisphenol A, 4,4'-dichlorodiphenyl sulfone, disodium diphenyl sulfone-4,4'-dichloro-3,3'-disulfonic acid, K2CO3, toluene and N-methylpyrrolidone were added into a flask in a ratio of 8:4:4:3:27:54, stirred at room temperature for 1 hour to mix evenly, then heated to 150°C for reaction for 3 hours, then heated to 190°C for further reaction for 8 hours, and after the reaction was completed, the obtained copolymer was washed 5 times with pure water and anhydrous ethanol respectively to obtain a terpolymer;

[0029] (2) The terpolymer, polysulfone, allyl o-diphenol, initiator and solvent were mixed uniformly in a ratio of 9:9:9:1.0:72, heated to 100° C. and stirred for 12 h, and then degassed in a vacuum at a negative pressure of 0.5 MPa for 6 h to obtain a casting solution for in-situ grafting; the initiator was azobisisobutyronitrile; and the solvent was N,N-dimethylformamide;

[0030] (3) Using non-woven fabric as a support material, the casting solution was reacted with pure water at a temperature of 15° C. for 0.5 min by a non-solvent phase separation method, and washed with hot water at 70° C. to form an ultrafiltration membrane, and the obtained ultrafiltration membrane was immersed in a 15 g / L NaOH solution for 24 h; the thickness of the non-woven fabric was 3.3 mil, and the total thickness of the ultrafiltration membrane was 6.0 mil;

[0031] (4) The antimicrobial peptide and pure water are prepared in a ratio of 10:90 and stirred evenly, the ultrafiltration membrane obtained in step (3) is immersed in the antimicrobial peptide solution at room temperature for 8 hours, then washed with pure water 5 times, and finally immersed in 15wt% glycerol for treatment and then blown dry to obtain an antibacterial and antifouling ultrafiltration membrane.

[0032] Example 2

[0033] A method for preparing an antibacterial and antifouling ultrafiltration membrane comprises the following steps:

[0034] (1) 2,2'-allyl bisphenol A, 4,4'-dichlorodiphenyl sulfone, disodium diphenyl sulfone-4,4'-dichloro-3,3'-disulfonic acid, K2CO3, toluene and N-methyl pyrrolidone were added into a flask in a ratio of 15:7.5:7.5:10:20:40, stirred at room temperature for 2 h to mix evenly, then heated to 155° C. for reaction for 4 h, then heated to 190° C. for further reaction for 8 h, and after the reaction was completed, the obtained copolymer was washed 5 times with pure water and anhydrous ethanol respectively to obtain a terpolymer;

[0035] (2) The terpolymer, polyethersulfone, allyl o-diphenol, initiator and solvent were mixed uniformly in a ratio of 7:7:7:0.5:78.5, heated to 90° C. and stirred for 10 h, and then degassed in a vacuum at a negative pressure of 0.4 MPa for 5 h to obtain a casting solution for in-situ grafting; the initiator was diisopropylbenzene peroxide; and the solvent was Isopar G;

[0036] (3) Using non-woven fabric as a support material, the casting solution was reacted with 14° C. pure water for 0.75 min by a non-solvent phase separation method, and then washed with 75° C. hot water to form an ultrafiltration membrane, and the obtained ultrafiltration membrane was immersed in a 20 g / L NaOH solution for 36 h; the thickness of the non-woven fabric was 3.6 mil, and the total thickness of the ultrafiltration membrane was 6.2 mil;

[0037] (4) The antimicrobial peptide and pure water are prepared in a ratio of 15:85 and stirred evenly, the ultrafiltration membrane obtained in step (3) is immersed in the antimicrobial peptide solution, immersed at room temperature for 10 hours, then washed with pure water 5 times, and finally immersed in 20wt% glycerol for treatment and then blown dry to obtain an antibacterial and antifouling ultrafiltration membrane.

[0038] Experimental Example 1

[0039] In the water contact angle test, the water contact angle of the ultrafiltration membrane prepared by pure polysulfone or polyethersulfone is 92.8±3.1°, and the water contact angle of the antibacterial and antifouling ultrafiltration membrane prepared by the present invention is 26.8±3.4°, indicating that compared with the ultrafiltration membrane prepared by pure polysulfone or polyethersulfone, the hydrophilicity of the antibacterial and antifouling ultrafiltration membrane prepared by the present invention is significantly enhanced.

[0040] Experimental Example 2

[0041] The pure polysulfone or polyethersulfone ultrafiltration membrane and the antibacterial and antifouling ultrafiltration membrane prepared by the present invention were run simultaneously in the membrane test, and the solution was switched every 10 minutes between pure water operation and 50-100ppm BSA solution operation for 3 cycles. When the ultrafiltration membrane prepared by the present invention was run in BSA solution, the membrane flux decreased less, and the membrane flux recovery rate was higher after switching to pure water operation. After 3 runs, the membrane flux was well recovered; Figure 1 It can be seen that the antibacterial and antifouling ultrafiltration membrane prepared in the present invention has good performance in the BSA cycle pollution test.

[0042] Example 3

[0043] The pure polysulfone or polyethersulfone ultrafiltration membrane and the antibacterial and antifouling ultrafiltration membrane prepared by the present invention were run simultaneously in a membrane test bench, and the running solution contained 5×10 5CUF / mL liquid culture medium of Escherichia coli or Staphylococcus aureus, the operation time is 24-48h, after the operation, the membrane is taken out, and then the two groups of membranes are placed in culture dishes respectively, and the surface of the membrane is covered with a cover glass to prevent the bacterial solution from evaporating to the death of bacteria. After the culture dish is sealed, it is placed in a constant temperature and humidity incubator for 12-24h, and then the membrane is taken out, and the membrane is rinsed with 10-20mL of physiological saline and the rinse liquid is evenly applied on the sterile solid culture medium. After sealing, it is cultured in a constant temperature and humidity incubator for 12-24h. The bacterial growth conditions are as follows Figure 2 , Figure 3 As shown. In the bacterial culture sample corresponding to the ultrafiltration membrane prepared by the present invention, the number of bacteria is significantly less. According to the antibacterial rate calculation results, the antibacterial rates of the ultrafiltration membrane prepared by the present invention against Escherichia coli and Staphylococcus aureus are both above 90%, and have good antibacterial properties.

[0044] The preparation method of the pure polysulfone or polyethersulfone ultrafiltration membrane is:

[0045] (1) uniformly mixing polysulfone or polyethersulfone with a solvent in a mass ratio of 16-22:78-84; heating and stirring at 85-95° C. for 4-8 hours, and then vacuum filtering for 2-4 hours to obtain a casting solution;

[0046] (2) The supporting material is a non-woven fabric, and the casting liquid is reacted with the supporting material by a liquid-solid phase conversion method to obtain a polysulfone or polyethersulfone ultrafiltration membrane. The phase conversion time in the liquid-solid phase conversion method is 0.5-1 min, the phase conversion water bath temperature is 12-15° C., and the heat curing water bath temperature is 60-80° C.

Claims

1. A method for preparing an antibacterial and antifouling ultrafiltration membrane, characterized in that: The steps include: (1) Add 2,2'-allyl bisphenol A, 4,4'-dichlorodiphenyl sulfone, disodium diphenyl sulfone-4,4'-dichloro-3,3'-disulfonate, K2CO3, toluene and N-methylpyrrolidone into a flask, stir evenly at room temperature, then heat to 140-155°C and keep warm for 2-4 hours, then heat to 180-190°C and keep warm for 6-8 hours. After the reaction is completed, wash the obtained copolymer with pure water and anhydrous ethanol for 3-5 times respectively to obtain a terpolymer; (2) The terpolymer, polysulfone or polyethersulfone, allyl o-diphenol, initiator and solvent are mixed uniformly, heated to 80-100° C. and stirred for 6-12 hours, and then vacuum degassed at a negative pressure of 0.3-0.5 MPa for 4-6 hours to obtain an in-situ grafted casting solution; (3) using non-woven fabric as a support material, reacting the in-situ grafted casting solution with pure water by a non-solvent phase separation method, washing with hot water to form an ultrafiltration membrane, and soaking the ultrafiltration membrane in a NaOH solution for 24-48 hours; (4) The antimicrobial peptide and pure water are stirred evenly to obtain an antimicrobial peptide solution, and then the ultrafiltration membrane obtained in step (3) is immersed in the antimicrobial peptide solution at room temperature for 6-10 hours, and then washed with pure water for 3-5 times, and finally immersed in 10-20wt% glycerol for treatment and then blown dry to obtain an antimicrobial and antifouling ultrafiltration membrane.

2. The method for preparing an antibacterial and antifouling ultrafiltration membrane according to claim 1, characterized in that: In step (1), the ratio of 2,2'-allyl bisphenol A, 4,4'-dichlorodiphenyl sulfone, disodium diphenyl sulfone-4,4'-dichloro-3,3'-disulfonate, K2CO3, toluene and N-methylpyrrolidone is 8-15:4-7.5:4-7.5:3-10:20-27:40-54.

3. The method for preparing an antibacterial and antifouling ultrafiltration membrane according to claim 1, characterized in that: In step (2), the ratio of the terpolymer, polysulfone or polyethersulfone, allyl o-diphenol, initiator and solvent is 7-9:7-9:7-9:0.5-1.0:72-78.

5.

4. The method for preparing an antibacterial and antifouling ultrafiltration membrane according to claim 1, characterized in that: In step (2), the initiator is any one or more of azobisisobutyronitrile, dicumyl peroxide, and benzoyl peroxide; and the solvent is any one or more of N,N-dimethylformamide, Isopar G, N-methylpyrrolidone, and dimethylacetamide.

5. The method for preparing an antibacterial and antifouling ultrafiltration membrane according to claim 1, characterized in that: In step (3), the thickness of the non-woven fabric is 3.2-3.6 mil; the total thickness of the ultrafiltration membrane is 5.8-6.5 mil.

6. The method for preparing an antibacterial and antifouling ultrafiltration membrane according to claim 1, characterized in that: In step (3), the process conditions of the non-solvent phase separation method are: phase inversion time is 0.5-1 min, and the phase inversion water bath temperature is 12-25°C.

7. The method for preparing an antibacterial and antifouling ultrafiltration membrane according to claim 1, characterized in that: In step (3), the temperature of the hot water is 60-75°C.

8. The method for preparing an antibacterial and antifouling ultrafiltration membrane according to claim 1, characterized in that: In step (3), the concentration of the NaOH solution is 10-20 g / L.

9. An antibacterial and antifouling ultrafiltration membrane prepared by the method for preparing an antibacterial and antifouling ultrafiltration membrane according to any one of claims 1 to 8.

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