Modified polyethersulfone hollow fiber membrane as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of filter membrane materials, and particularly relates to a modified polyether sulfone hollow fiber membrane as well as a preparation method and application thereof. The modified polyethersulfone hollow fiber membrane provided by the invention comprises a base membrane and polymethylacrylic acid-N, N-dimethylaminoethyl ester grafted on the surface and / or in holes of the base membrane, and the base membrane is a polyether sulfone hollow fiber membrane. The polyethersulfone hollow fiber membrane is taken as a base membrane, and polymethylacrylic acid-N, N-dimethylaminoethyl ester is introduced into the base membrane, so that the hydrophilicity of the modified polyethersulfone hollow fiber membrane is improved, and the pollution resistance of the modified polyethersulfone hollow fiber membrane is improved; when the modified polyethersulfone hollow fiber membrane provided by the invention is used as a filter membrane for filtering beer, the problem of pollution in the beer filtering process is reduced while relatively high filtering precision is achieved, so that the filtering efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of filter membrane materials, and in particular relates to a modified polyethersulfone hollow fiber membrane and a preparation method and application thereof. Background Art

[0002] Beer filtration is an important part of beer production. Its purpose is to remove impurities such as suspended matter, sediment and microorganisms in beer to improve the clarity and stability of beer. Most traditional methods use diatomaceous earth as the filtration medium, but its filtration accuracy is poor, which affects the quality of beer. In recent years, hollow fiber membranes have been applied to beer filtration. They have the advantages of high filtration accuracy and large liquid production. Using hollow fiber membranes to filter beer has gradually become the mainstream method of beer filtration. Currently, commonly used hollow fiber membrane materials include cellulose filter membranes, polypropylene filter membranes, polysulfone filter membranes or polyethersulfone filter membranes. However, these materials are easily contaminated during the filtration process, affecting the filtration efficiency. Summary of the invention

[0003] In view of this, the present invention provides a modified polyethersulfone hollow fiber membrane and a preparation method and application thereof. The modified polyethersulfone hollow fiber membrane provided by the present invention has high pollution resistance and has high filtration efficiency when used as a filter membrane to filter beer.

[0004] In order to solve the above technical problems, the present invention provides a modified polyethersulfone hollow fiber membrane, comprising a base membrane and polymethacrylate-N,N-dimethylaminoethyl grafted on the surface and / or pores of the base membrane;

[0005] The base membrane is a polyethersulfone hollow fiber membrane.

[0006] Preferably, the grafting amount of poly(methacrylate)-N,N-dimethylaminoethyl ester in the modified polyethersulfone hollow fiber membrane is 0.05-25 wt %.

[0007] Preferably, the average pore size of the pores in the polyethersulfone hollow fiber membrane is 0.45 to 0.65 μm;

[0008] The porosity of the modified polyethersulfone hollow fiber membrane is 75-90%.

[0009] The present invention also provides a method for preparing the modified polyethersulfone hollow fiber membrane described in the above technical solution, comprising the following steps:

[0010] The polyethersulfone hollow fiber membrane, N,N-dimethylaminoethyl methacrylate, a photoinitiator and water are mixed and ultraviolet grafting is performed to obtain the modified polyethersulfone hollow fiber membrane.

[0011] Preferably, the mixing comprises the following steps:

[0012] first mixing a photoinitiator and a portion of water to obtain a photoinitiator solution;

[0013] The N,N-dimethylaminoethyl methacrylate and the remaining portion of water are mixed for a second time to obtain an N,N-dimethylaminoethyl methacrylate solution;

[0014] first immersing the polyethersulfone hollow fiber membrane in the photoinitiator solution to obtain a photoinitiator adsorbed base membrane;

[0015] The photoinitiator adsorption base film is immersed in the N,N-dimethylaminoethyl methacrylate solution for a second time.

[0016] Preferably, the photoinitiator includes one or more of benzophenone, benzoin dimethyl ether and azobisisobutyronitrile.

[0017] Preferably, the mass concentration of the photoinitiator solution is 2 to 50 g / L.

[0018] Preferably, the mass concentration of the N,N-dimethylaminoethyl methacrylate solution is 30-100%.

[0019] Preferably, the UV grafting time is 2 to 30 minutes.

[0020] The present invention also provides the use of the modified polyethersulfone hollow fiber membrane described in the above technical solution or the modified polyethersulfone hollow fiber membrane prepared by the preparation method described in the above technical solution in beer filtration.

[0021] The present invention provides a modified polyethersulfone hollow fiber membrane, comprising a base membrane and polymethacrylate-N,N-dimethylaminoethyl grafted on the surface and / or pores of the base membrane; the base membrane is a polyethersulfone hollow fiber membrane. The present invention uses the polyethersulfone hollow fiber membrane as the base membrane and introduces polymethacrylate-N,N-dimethylaminoethyl into the base membrane to improve the hydrophilicity of the modified polyethersulfone hollow fiber membrane, thereby improving its pollution resistance; using the modified polyethersulfone hollow fiber membrane provided by the present invention as a filter membrane to filter beer has a high filtration accuracy while reducing its pollution problem in the beer filtration process, thereby improving the filtration efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The infrared spectra of the modified polyethersulfone hollow fiber membrane and the polyethersulfone hollow fiber membrane prepared in Examples 1 to 4 are shown. DETAILED DESCRIPTION

[0023] The present invention provides a modified polyethersulfone hollow fiber membrane, comprising a base membrane and polymethacrylate-N,N-dimethylaminoethyl grafted on the surface and / or pores of the base membrane;

[0024] The base membrane is a polyethersulfone hollow fiber membrane.

[0025] As a specific embodiment of the present invention, the polyethersulfone hollow fiber membrane can be a polyethersulfone hollow fiber membrane prepared by a phase inversion method; the average pore size of the pores in the polyethersulfone hollow fiber membrane can be 0.45 to 0.65 μm, specifically 0.45 μm, 0.5 μm 0.55 μm, 0.6 μm or 0.65 μm. In the present invention, the polyethersulfone hollow fiber membrane has a high through-hole structure and high porosity, which can provide abundant channels for filtering beer liquid, while reducing the mass transfer resistance during the filtration process and improving the filtration efficiency.

[0026] As a specific embodiment of the present invention, the grafting amount of polymethacrylate-N,N-dimethylaminoethyl ester in the modified polyethersulfone hollow fiber membrane can be 0.05-25wt%, and can be specifically 0.1wt%, 1wt%, 5wt%, 10wt%, 15wt%, 15wt%, 20wt% or 25wt%. The present invention introduces hydrophilic polymethacrylate-N,N-dimethylaminoethyl ester (containing hydrophilic tertiary amine groups) into the base membrane to improve the hydrophilicity of the modified polyethersulfone hollow fiber membrane, thereby improving its pollution resistance.

[0027] As a specific embodiment of the present invention, the porosity of the modified polyethersulfone hollow fiber membrane may be 75-90%, or 80-85%.

[0028] The present invention also provides a method for preparing the modified polyethersulfone hollow fiber membrane described in the above technical solution, comprising the following steps:

[0029] The polyethersulfone hollow fiber membrane, N,N-dimethylaminoethyl methacrylate, a photoinitiator and water are mixed and ultraviolet grafting is performed to obtain the modified polyethersulfone hollow fiber membrane.

[0030] In the present invention, unless otherwise specified, all materials are conventional commercially available products.

[0031] As a specific embodiment of the present invention, the mixing may include the following steps:

[0032] first mixing a photoinitiator and a portion of water to obtain a photoinitiator solution;

[0033] The N,N-dimethylaminoethyl methacrylate and the remaining portion of water are mixed for a second time to obtain an N,N-dimethylaminoethyl methacrylate solution;

[0034] first immersing the polyethersulfone hollow fiber membrane in the photoinitiator solution to obtain a photoinitiator adsorbed base membrane;

[0035] The photoinitiator adsorption base film is immersed in the N,N-dimethylaminoethyl methacrylate solution for a second time.

[0036] The present invention first mixes the photoinitiator and part of the water to obtain a photoinitiator solution. As a specific embodiment of the present invention, the photoinitiator may include one or more of benzophenone, benzoin dimethyl ether and azobisisobutyronitrile, which may be specifically benzophenone, benzoin dimethyl ether or azobisisobutyronitrile; the water may be deionized water. The present invention has no special requirements for the first mixing, as long as it can be mixed evenly. As a specific embodiment of the present invention, the mass concentration of the photoinitiator solution may be 2 to 50 g / L, which may be specifically 2 g / L, 3 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L or 50 g / L.

[0037] The present invention performs a second mixing of N,N-dimethylaminoethyl methacrylate and the remaining part of water to obtain a N,N-dimethylaminoethyl methacrylate solution. The present invention has no special requirements for the second mixing, as long as it can be mixed evenly. As a specific embodiment of the present invention, the mass concentration of the N,N-dimethylaminoethyl methacrylate solution can be 30 to 100%, specifically 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%.

[0038] After obtaining the photoinitiator solution, the present invention first immerses the polyethersulfone hollow fiber membrane in the photoinitiator solution to obtain a photoinitiator adsorption base membrane. The present invention has no special limitation on the amount of the photoinitiator solution as long as it can be immersed. As a specific embodiment of the present invention, the first immersion time can be more than 2 hours, and can also be 2 to 4 hours.

[0039] After obtaining the N,N-dimethylaminoethyl methacrylate solution, the present invention immerses the photoinitiator adsorption base film in the N,N-dimethylaminoethyl methacrylate solution for a second time. The present invention has no particular limitation on the amount of the N,N-dimethylaminoethyl methacrylate solution as long as it can be immersed.

[0040] As a specific implementation of the present invention, the time of the UV grafting can be 2 to 30 minutes, and can be specifically 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes.

[0041] As a specific embodiment of the present invention, the UV grafting may further include: washing the UV grafted product to obtain the modified polyethersulfone hollow fiber membrane; the washing detergent may be an ethanol aqueous solution, and the mass concentration of the ethanol aqueous solution may be 60-75%.

[0042] The preparation method provided by the invention is simple and easy to operate and has high practical value.

[0043] The present invention also provides the use of the modified polyethersulfone hollow fiber membrane described in the above technical solution or the modified polyethersulfone hollow fiber membrane prepared by the preparation method described in the above technical solution in beer filtration. The modified polyethersulfone hollow fiber membrane provided by the present invention is used for beer clarification filtration, and the clarity after filtration is significantly improved, yeast cells are trapped, and the original wort and flavor substances can be better retained, while the occurrence of membrane pollution problems is reduced, and a higher beer liquid yield can be obtained.

[0044] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0045] Example 1

[0046] A polyethersulfone hollow fiber membrane with an average pore size of 0.65 μm was prepared by a phase inversion method.

[0047] Firstly, benzophenone and water are mixed to obtain a photoinitiator solution having a mass concentration of 5 g / L;

[0048] The polyethersulfone hollow fiber membrane is first immersed in a photoinitiator solution (immersed for 2.5 hours) to obtain a photoinitiator adsorbed base membrane;

[0049] The photoinitiator adsorbed base membrane is secondly immersed in methacrylate-N,N-dimethylaminoethyl ester monomer and irradiated under ultraviolet lamp for 5 minutes for ultraviolet grafting; the ultraviolet grafted product is washed with 70% ethanol aqueous solution to obtain a modified polyethersulfone hollow fiber membrane.

[0050] Example 2

[0051] A polyethersulfone hollow fiber membrane with an average pore size of 0.65 μm was prepared by a phase inversion method.

[0052] Firstly, azobisisobutyronitrile and water are mixed to obtain a photoinitiator solution with a mass concentration of 3 g / L;

[0053] The N,N-dimethylaminoethyl methacrylate and water are mixed for the second time to obtain an N,N-dimethylaminoethyl methacrylate solution having a mass concentration of 80%;

[0054] The polyethersulfone hollow fiber membrane is first immersed in a photoinitiator solution (immersed for 3 hours) to obtain a photoinitiator adsorbed base membrane;

[0055] The photoinitiator adsorbed base membrane is secondly immersed in methacrylate-N,N-dimethylaminoethyl ester solution and irradiated under ultraviolet lamp for 10 minutes for ultraviolet grafting; the ultraviolet grafted product is washed with 60% mass concentration of ethanol aqueous solution to obtain a modified polyethersulfone hollow fiber membrane.

[0056] Example 3

[0057] A polyethersulfone hollow fiber membrane with an average pore size of 0.45 μm was prepared by a phase inversion method.

[0058] Firstly mixing benzophenone and water to obtain a photoinitiator solution with a mass concentration of 3 g / L;

[0059] The N,N-dimethylaminoethyl methacrylate and water are mixed for the second time to obtain a 50% by mass concentration N,N-dimethylaminoethyl methacrylate solution;

[0060] The polyethersulfone hollow fiber membrane is first immersed in a photoinitiator solution (immersed for 3.5 hours) to obtain a photoinitiator adsorbed base membrane;

[0061] The photoinitiator adsorbed base membrane is secondly immersed in methacrylate-N,N-dimethylaminoethyl ester solution and irradiated under ultraviolet lamp for 20 minutes for ultraviolet grafting; the ultraviolet grafted product is washed with 65% mass concentration of ethanol aqueous solution to obtain a modified polyethersulfone hollow fiber membrane.

[0062] Example 4

[0063] A polyethersulfone hollow fiber membrane with an average pore size of 0.65 μm was prepared by a phase inversion method.

[0064] Firstly, benzophenone and water are mixed to obtain a photoinitiator solution having a mass concentration of 20 g / L;

[0065] The N,N-dimethylaminoethyl methacrylate and water are mixed for the second time to obtain a 50% by mass concentration N,N-dimethylaminoethyl methacrylate solution;

[0066] The polyethersulfone hollow fiber membrane is first immersed in a photoinitiator solution (immersed for 4 hours) to obtain a photoinitiator adsorbed base membrane;

[0067] The photoinitiator adsorbed base membrane is secondly immersed in methacrylate-N,N-dimethylaminoethyl ester solution and irradiated under ultraviolet lamp for 5 minutes for ultraviolet grafting; the ultraviolet grafted product is washed with 70% ethanol aqueous solution to obtain a modified polyethersulfone hollow fiber membrane.

[0068] Comparative Example 1

[0069] A polyethersulfone hollow fiber membrane with an average pore size of 0.65 μm prepared by a phase inversion method was used as a comparative example.

[0070] The modified polyethersulfone hollow fiber membrane and the polyethersulfone hollow fiber membrane (PES original membrane) prepared in Examples 1 to 4 were detected by Fourier transform infrared spectroscopy (TENSOR37, BrukerAXS) to obtain infrared spectra, as shown in FIG. Figure 1 As shown. Figure 1 It can be seen that the modified polyethersulfone hollow fiber membranes prepared in Examples 1 to 4 have a high conductivity at 1730 cm -1 There is an absorption peak at , which corresponds to the stretching vibration peak of C=O on poly(methacrylate)-N,N-dimethylaminoethyl ester (PDMAEMA), indicating that the grafted chain PDMAEMA has been grafted onto the surface of the polyethersulfone membrane.

[0071] The modified polyethersulfone hollow fiber membranes prepared in Examples 1 to 4 were tested for performance according to the following method, and the results are listed in Table 1:

[0072] The grafting amount of poly(methacrylate)-N,N-dimethylaminoethyl ester in the modified polyethersulfone hollow fiber membrane is calculated, that is, the percentage of the grafted chain weight to the main chain weight, expressed as mass percentage, and the calculation formula is as follows:

[0073]

[0074] Wherein, GD is the grafting ratio, m is the mass of the modified polyethersulfone hollow fiber membrane, and m0 is the mass of the blank membrane (the mass of the polyethersulfone hollow fiber membrane).

[0075] The porosity of the modified polyethersulfone hollow fiber membrane prepared in Examples 1 to 4 was tested by the dry-wet weight method; specifically, the wet membrane was weighed (Ww), and then dried in an electric blast drying oven at 60°C for 24 hours to remove moisture, and the mass of the membrane was weighed after drying (Wd). The porosity was calculated as follows:

[0076] ε=(Ww-Wd)×100% / Adρ;

[0077] Where: ε is the porosity of the membrane (%); Ww is the mass of the wet membrane (g); Wd is the mass of the dry membrane (g); A is the area of ​​the membrane (cm 2 ), d is the average thickness of the membrane (cm), ρ is the density of pure water (1.0 g / cm 3 ).

[0078] Table 1 Grafting amount and porosity of modified polyethersulfone hollow fiber membranes prepared in Examples 1 to 4

[0079] Example Grafting amount (wt%) Porosity (%) Example 1 15 85 Example 2 20 80 Example 3 18 82 Example 4 10 89

[0080] The modified polyethersulfone hollow fiber membranes prepared in Examples 1 to 4 and the polyethersulfone hollow fiber membranes in Comparative Example 1 were used to perform a filtration test on beer: the beer filtration performance of the modified polyethersulfone hollow fiber membranes was measured using a beer filtration device. The number of yeasts was measured using a Count starTY1100 I-03 yeast counter; the original wort concentration and alcohol content were measured using an Anton Paar / Type III beer fully automatic analyzer; and the turbidity was measured using a Haffmans / VOS90 / 25 dual-angle turbidity meter. The results of the feed liquid quality indicators before and after membrane filtration are listed in Table 2.

[0081] Table 2 Quality indexes of beer liquid before and after membrane filtration

[0082] index Beer stock solution Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Yeast count (10,000 / mL) 64 1.5 1.39 0.25 0.67 5 Original wort concentration (°P) 12.84 12.54 12.57 12.76 12.76 12.83 Turbidity (90°) 99 0.5 0.54 0.74 0.35 2.5

[0083] It can be seen from the results in Tables 1 and 2 that the poly(methacrylate)-N,N-dimethylaminoethyl ester) having a hydrophilic tertiary amine group in the polyethersulfone hollow fiber membrane of the present invention makes the modified polyethersulfone membrane have stronger pollution resistance, thereby reducing the pollution problem in the membrane beer filtration process and improving the clarity and filtration efficiency of the beer.

[0084] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A modified polyethersulfone hollow fiber membrane, characterized in that: It comprises a base film and polymethacrylate-N,N-dimethylaminoethyl ester grafted on the surface and / or pores of the base film; The base membrane is a polyethersulfone hollow fiber membrane.

2. The modified polyethersulfone hollow fiber membrane according to claim 1, characterized in that: The grafting amount of poly(methacrylate)-N,N-dimethylaminoethyl ester in the modified polyethersulfone hollow fiber membrane is 0.05-25 wt %.

3. The modified polyethersulfone hollow fiber membrane according to claim 1 or 2, characterized in that: The average pore size of the polyethersulfone hollow fiber membrane is 0.45 to 0.65 μm; The porosity of the modified polyethersulfone hollow fiber membrane is 75-90%.

4. The method for preparing the modified polyethersulfone hollow fiber membrane according to any one of claims 1 to 3, characterized in that: The following steps are involved: The polyethersulfone hollow fiber membrane, N,N-dimethylaminoethyl methacrylate, a photoinitiator and water are mixed and ultraviolet grafting is performed to obtain the modified polyethersulfone hollow fiber membrane.

5. The preparation method according to claim 4, characterized in that: The mixing comprises the following steps: first mixing a photoinitiator and a portion of water to obtain a photoinitiator solution; The N,N-dimethylaminoethyl methacrylate and the remaining portion of water are mixed for a second time to obtain an N,N-dimethylaminoethyl methacrylate solution; first immersing the polyethersulfone hollow fiber membrane in the photoinitiator solution to obtain a photoinitiator adsorbed base membrane; The photoinitiator adsorption base film is immersed in the N,N-dimethylaminoethyl methacrylate solution for a second time.

6. The preparation method according to claim 5, characterized in that: The photoinitiator includes one or more of benzophenone, benzoin dimethyl ether and azobisisobutyronitrile.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The mass concentration of the photoinitiator solution is 2-50 g / L.

8. The preparation method according to claim 5, characterized in that: The mass concentration of the N,N-dimethylaminoethyl methacrylate solution is 30-100%.

9. The preparation method according to claim 4, 5, 6 or 8, characterized in that: The ultraviolet grafting time is 2 to 30 minutes.

10. Use of the modified polyethersulfone hollow fiber membrane according to any one of claims 1 to 3 or the modified polyethersulfone hollow fiber membrane prepared by the preparation method according to any one of claims 4 to 9 in beer filtration.

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