CN106861437B - Preparation method of stable high-flux ultrafiltration membrane - Google Patents
Preparation method of stable high-flux ultrafiltration membrane Download PDFInfo
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- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/14—Ultrafiltration; Microfiltration
- B01D61/145—Ultrafiltration
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Abstract
The invention discloses a preparation method of a stable high-flux ultrafiltration membrane. The method mainly comprises the following steps: preparing a modifier precursor poly (N-vinyl pyrrolidone-alt-maleic anhydride) -b-polystyrene by adopting a free radical polymerization method; dissolving a modifier precursor, polyethylene glycol 2000 and polyether sulfone in N, N-dimethylformamide to prepare a membrane casting solution, and stirring and heating the membrane casting solution, wherein the modifier with a cross-linking structure is generated in situ in the process through an acid anhydride alcoholysis reaction; finally, preparing the stable high-flux ultrafiltration membrane by a non-solvent induced phase inversion method. The invention has the advantages that: the preparation method can adjust the cross-linking degree and other structures of the in-situ generated modifier by changing the feeding ratio of the modifier precursor and the polyethylene glycol 2000, further regulate and control the composition structure and the performance of the ultrafiltration membrane, and realize stable high flux and good separation performance.
Description
Technical Field
The invention relates to a preparation method of a stable high-flux ultrafiltration membrane, belonging to the technical field of preparation of ultrafiltration membranes.
Background
Membrane separation is a high and new technology covering multiple disciplines of chemical engineering, material science, process engineering and the like, and is a separation medium which has selectivity on a certain component in a mixture, and a certain driving force is applied to two sides of a membrane so that the component in the mixture is selectively transferred from one side of the membrane to the other side. The ultrafiltration membrane is one of membrane separation technologies which take pressure as a driving force and aim at the separation of macromolecules and micromolecules. As a novel separation technology, the ultrafiltration membrane can effectively retain suspended particles, colloids, macromolecules, algae, bacteria and the like, and is applied in many aspects. Seawater desalination pretreatment is one of the important applications of ultrafiltration technology, but in the practical application process, the ultrafiltration technology still faces the problems of low treatment flux, serious membrane pollution and the like.
The membrane pollution generally refers to that the effective pore size of the membrane is gradually reduced and blocked due to the phenomena of adsorption, deposition and the like on the surface or in the pore channels of the membrane, even a filter cake layer or a gel layer is formed, so that the permeation flux of the membrane is continuously reduced and is consistent and cannot be used due to the physical, chemical, biochemical or mechanical effects of particles such as proteins and organic matters, micelles, microorganisms and the like in the treated feed liquid. There are many ways to improve and mitigate membrane fouling to extend the useful life of the membrane, for example: increasing the flow rate of feed liquid on the surface of the membrane, establishing and optimizing a cleaning scheme, developing an ultrafiltration membrane with anti-pollution performance and the like, wherein the development of the anti-pollution ultrafiltration membrane is a fundamental way for solving the problem of membrane pollution.
The construction of the existing anti-pollution membrane mostly follows the four anti-pollution principles of Whitesids, and the group with the following four characteristics effectively inhibits the nonspecific adsorption of biological pollutants (proteins): (1) strong hydrophilicity; (2) a hydrogen bond acceptor; (3) a non-hydrogen bond donor; (4) is electrically neutral. Despite extensive research, the general principle of anti-fouling surface construction to date has been to increase the hydrophilicity of the surface, i.e., to construct a strongly hydrophilic anti-fouling surface.
Heretofore, hydrophilic anti-fouling materials which can exert a good anti-fouling effect and have been widely recognized mainly include polyoxyethylene-based polymers, zwitterionic-based polymers and other hydrophilic anti-fouling materials. Surface modification methods commonly used today are surface coating, surface grafting and surface segregation. Because the surface coating and the surface grafting are used for modifying the surface of the membrane after the membrane is formed, the surface of the membrane can be effectively modified, but the pores of the membrane are still damaged by pollutants. The surface segregation is an in-situ three-dimensional modification method, and the membrane is modified in the membrane formation process, so that the surface of the membrane can be modified, membrane pores can be effectively modified, and the pollution of pollutants to the membrane pores is reduced, thereby gaining wide attention.
The surface segregation agent mainly comprises two parts, namely a hydrophilic section and a hydrophobic section, wherein the two parts play different roles in the surface segregation process. In the surface segregation process, the hydrophilic section can migrate from the casting solution to the gel bath due to better water solubility, and the surface of the membrane pores exist in the membrane forming process, so that the surface modification effect is realized; and the hydrophobic section plays a role in anchoring the hydrophilic section due to the hydrophobic interaction of the hydrophobic section and the membrane main body material, so that the hydrophilic section can stably exist on the surface of the membrane.
At present, surface segregation is regulated and controlled by adopting a mode of low hydrophilic-hydrophobic segment proportion, and loss of a surface segregation agent in a non-solvent bath in a non-solvent induced phase transformation process is inhibited, but the mode also causes enrichment of more hydrophobic segments on the surface of a membrane, and has adverse effect on a modification effect. The invention regulates and controls the surface segregation by regulating and controlling the crosslinking degree of the hydrophilic section, promotes the enrichment of the hydrophilic section on the surface of the membrane while inhibiting the loss of a surface segregation agent, and endows the membrane with stable and high-flux performance.
Disclosure of Invention
The invention aims to provide a preparation method of a stable high-flux ultrafiltration membrane, the preparation method is simple and easy to operate, and the prepared ultrafiltration membrane has stable high flux and good separation performance.
In order to solve the technical problems, the preparation method of the stable high-flux ultrafiltration membrane provided by the invention comprises the following steps:
step one, preparing a modifier precursor: mixing maleic anhydride, N-vinyl pyrrolidone and N, N-dimethylformamide into a uniform solution according to the mass ratio of 1:1:10, taking azobisisobutyronitrile with the equivalent of 5 percent of the total mass of the maleic anhydride and the N-vinyl pyrrolidone as an initiator, carrying out radical alternating copolymerization for 3h at 70 ℃, then adding styrene to continue polymerizing for 3h, wherein the mass ratio of the styrene to the maleic anhydride is 4:1, and the structure of the finally obtained modifier precursor is a poly (N-vinyl pyrrolidone-alt-maleic anhydride) -b-polystyrene like block copolymer;
step two, in-situ synthesis of a modifier and preparation of a stable high-flux ultrafiltration membrane: mixing the modifier precursor prepared in the step one, polyethylene glycol 2000, polyether sulfone and N, N-dimethylformamide according to the mass ratio of 1-3: 6:16: 75-77, stirring at 60 ℃ for 12 hours, carrying out an acid anhydride alcoholysis reaction on the modifier precursor and the polyethylene glycol 2000 to generate a modifier with a cross-linking structure in situ, and fully mixing the modifier precursor and the polyether sulfone to form a uniform casting solution; and then standing and defoaming the membrane casting solution at 60 ℃ for 46h, cooling to room temperature, pouring the membrane casting solution on a glass plate to scrape a membrane, putting the membrane casting solution into a water bath at 25 ℃ to solidify into a membrane, taking the membrane out of the glass plate, and soaking the membrane in deionized water for 24h to obtain the stable high-flux ultrafiltration membrane.
The ultrafiltration membrane prepared by the preparation method provided by the invention has the pure water specific flux of 265-351 Lm-2h- 1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 96-98%, and the recovery rates of three circulation fluxes are 54.1-79.1% respectively; 93.0 to 100.0% and 93.9 to 100%.
The invention has the advantages that: the preparation method can adjust the cross-linking degree and other structures of the in-situ generated modifier by changing the feeding ratio of the modifier precursor and the polyethylene glycol 2000, further regulate and control the composition structure and the performance of the ultrafiltration membrane, and realize stable high flux and good separation performance.
Drawings
FIG. 1 is a graph showing the three-cycle flux change of a 1g/L bovine serum protein solution filtered by a comparative membrane prepared in the comparative example, wherein the contents of each cycle are as follows: pure water (30min) -protein solution (60min) -rinse (20min, time not shown in the figure) -pure water (30 min).
FIG. 2 is a graph showing the three-cycle flux change of a 1g/L bovine serum protein solution filtered by a stable high-flux ultrafiltration membrane 3 according to example 3 of the present invention, wherein each cycle comprises: pure water (30min) -protein solution (60min) -rinse (20min, time not shown in the figure) -pure water (30 min).
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following specific embodiments and the attached table, and the described specific embodiments are only illustrative of the present invention and are not intended to limit the present invention.
Example 1, a stable high-throughput ultrafiltration membrane was prepared by the following steps:
step one, preparing a modifier precursor: dissolving maleic anhydride and N-vinyl pyrrolidone in a certain amount of N, N-dimethylformamide, taking azobisisobutyronitrile as an initiator, carrying out radical alternating copolymerization for 3h at 70 ℃, then adding styrene to continue polymerization for 3h, and finally obtaining a block copolymer with a structure of poly (N-vinyl pyrrolidone-alt-maleic anhydride) -b-polystyrene (the feeding ratio of maleic anhydride, N-vinyl pyrrolidone and styrene is 1:1: 4);
step two, in-situ synthesis of a modifier and preparation of a stable high-flux ultrafiltration membrane: mixing the modifier precursor 100mg prepared in the step one, polyethylene glycol 2000600 mg, polyether sulfone 1600mg and N, N-dimethylformamide 7700mg (mass ratio is 1:6:16:77) into a uniform solution, stirring at 60 ℃ for 12h, carrying out in-situ reaction on the modifier precursor and polyethylene glycol 2000 through acid anhydride alcoholysis reaction to generate a modifier with a cross-linking structure, and fully mixing the modifier precursor and polyether sulfone into a uniform casting solution. And standing the membrane casting solution at 60 ℃ for defoaming for 46h, cooling to room temperature, pouring the membrane casting solution on a glass plate for membrane scraping, putting the glass plate into a water bath at 25 ℃ for solidification to form a membrane, taking the membrane from the glass plate, and soaking the membrane in deionized water for 24h to obtain the stable high-flux ultrafiltration membrane, which is marked as the stable high-flux ultrafiltration membrane 1.
The stable high-flux ultrafiltration membrane 1 prepared in example 1 has a pure water specific flux of 265Lm-2h-1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 98%, and the recovery rates of the three circulation fluxes are 77.4%, 95.8% and 93.9%, respectively.
Example 2, a stable high-flux ultrafiltration membrane was prepared by substantially the same procedure as in example 1, except that: in the second step, the mass ratio of the modifier precursor, the polyethylene glycol 2000, the polyether sulfone and the N, N-dimethylformamide is changed to 1.5:6:16:76.5, and finally the stable high-flux ultrafiltration membrane 2 is prepared.
The stable high-flux ultrafiltration membrane 2 prepared in the example 2 has the specific flux of 289Lm in pure water-2h-1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 97%, and the recovery rates of three circulation fluxes are 79.1%, 93.0% and 96.7% respectively.
Example 3 a stable high-throughput ultrafiltration membrane was prepared by essentially the same procedure as in example 1, except that: in the second step, the mass ratio of the modifier precursor, the polyethylene glycol 2000, the polyether sulfone and the N, N-dimethylformamide is changed to 2:6:16:76, and finally the stable high-flux ultrafiltration membrane 3 is prepared.
The stable high-flux ultrafiltration membrane 3 prepared in example 3 has a pure water specific flux of 316Lm-2h-1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 97%, and the recovery rates of the three circulation fluxes are 75.0%, 98.2% and 100.0% respectively. FIG. 2 shows a stable high-throughput ultrafiltration membrane 3 for filtering 1g/L bovine serum albuminThree cycles of flux profiles for the solutions.
Example 4 a stable high-throughput ultrafiltration membrane was prepared by essentially the same procedure as in example 1, except that: in the second step, the mass ratio of the modifier precursor, the polyethylene glycol 2000, the polyether sulfone and the N, N-dimethylformamide is changed to 2.5:6:16:75.5, and finally the stable high-flux ultrafiltration membrane 4 is prepared.
The stable high-flux ultrafiltration membrane 4 prepared in example 4 has a pure water specific flux of 340Lm-2h-1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 97%, and the recovery rates of the three circulation fluxes are 61.0%, 100.0% and 99.0%, respectively.
Example 5 a stable high-throughput ultrafiltration membrane was prepared by essentially the same procedure as in example 1, except that: in the second step, the mass ratio of the modifier precursor, the polyethylene glycol 2000, the polyether sulfone and the N, N-dimethylformamide is changed to 3:6:16:75, and finally the stable high-flux ultrafiltration membrane 5 is prepared.
The stable high-flux ultrafiltration membrane 5 prepared in example 5 has a pure water specific flux of 351Lm-2h-1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 96%, and the recovery rates of three circulation fluxes are 54.1%, 100.0% and 98.2%, respectively.
Comparative example a stable high-throughput ultrafiltration membrane was prepared, which was prepared substantially in the same manner as in example 1, except that: in the second step, the mass ratio of the modifier precursor, the polyethylene glycol 2000, the polyether sulfone and the N, N-dimethylformamide is changed to 0:6:16:7.8, and finally the ultrafiltration membrane is prepared and marked as a contrast membrane.
Comparative example comparative film having a pure water specific flux of 95Lm-2h-1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 98%, and the recovery rates of the three circulation fluxes are 72.8%, 83.4% and 81.8% respectively. FIG. 1 is a graph showing the three-cycle flux changes of a 1g/L bovine serum protein solution filtered by a control membrane.
The flux and separation performance of the stable high-flux ultrafiltration membranes prepared in examples 1 to 5 of the present invention and the ultrafiltration membrane prepared in the comparative example were compared as shown in table 1:
TABLE 1
In summary, the preparation method can adjust the cross-linking degree and other structures of the in-situ generated modifier by changing the feeding ratio of the modifier precursor and the polyethylene glycol 2000, further regulate and control the composition structure and the performance of the ultrafiltration membrane, and realize stable high flux and good separation performance. With the increase of the feeding amount of the modifier precursor, the pure water flux of the ultrafiltration membrane is increased, the bovine serum albumin retention rate is kept unchanged, the anti-pollution performance is improved and then reduced, and the comprehensive performance of the ultrafiltration membrane in the embodiment 3 reaches the optimal value.
While the invention has been described in connection with the drawings and tables, the present invention is not limited to the embodiments described above, which are intended to be illustrative rather than restrictive, and many modifications may be made by those skilled in the art without departing from the spirit of the invention within the scope of the appended claims.
Claims (2)
1. A preparation method of a stable high-flux ultrafiltration membrane is characterized by comprising the following steps:
step one, preparing a modifier precursor:
mixing maleic anhydride, N-vinyl pyrrolidone and N, N-dimethylformamide into a uniform solution according to the mass ratio of 1:1:10, taking azobisisobutyronitrile with the equivalent of 5 percent of the total mass of the maleic anhydride and the N-vinyl pyrrolidone as an initiator, carrying out radical alternating copolymerization for 3h at 70 ℃, then adding styrene to continue polymerizing for 3h, wherein the mass ratio of the styrene to the maleic anhydride is 4:1, and the structure of the finally obtained modifier precursor is a poly (N-vinyl pyrrolidone-alt-maleic anhydride) -b-polystyrene like block copolymer;
step two, in-situ synthesis of a modifier and preparation of a stable high-flux ultrafiltration membrane:
mixing the modifier precursor prepared in the step one, polyethylene glycol 2000, polyether sulfone and N, N-dimethylformamide according to the mass ratio of 1-3: 6:16: 75-77, stirring at 60 ℃ for 12 hours, carrying out an acid anhydride alcoholysis reaction on the modifier precursor and the polyethylene glycol 2000 to generate a modifier with a cross-linking structure in situ, and fully mixing the modifier precursor and the polyether sulfone to form a uniform casting solution; and then standing and defoaming the membrane casting solution at 60 ℃ for 46h, cooling to room temperature, pouring the membrane casting solution on a glass plate to scrape a membrane, putting the membrane casting solution into a water bath at 25 ℃ to solidify into a membrane, taking the membrane out of the glass plate, and soaking the membrane in deionized water for 24h to obtain the stable high-flux ultrafiltration membrane.
2. A stable high-flux ultrafiltration membrane, which is characterized in that the ultrafiltration membrane prepared by the preparation method of the stable high-flux ultrafiltration membrane in claim 1 has the specific flux of 265-351 Lm in pure water-2h-1bar-1The retention rate of 1g/L bovine serum albumin aqueous solution is 96-98%, and the recovery rates of three circulation fluxes are 54.1-79.1% respectively; 93.0 to 100.0% and 93.9 to 100%.
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| CN114345151B (en) * | 2022-03-01 | 2023-06-23 | 天津工业大学 | Polymer-based ultrafiltration membrane with high toughness and pollution resistance and preparation method thereof |
| CN114917764B (en) * | 2022-04-29 | 2023-10-24 | 浙江理工大学 | Method for preparing high-selectivity high-flux PES (polyether sulfone) ultrafiltration membrane by using monomer self-crosslinking |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2003000761A1 (en) * | 2001-06-21 | 2003-01-03 | Basf Coatings Ag | Coated medium-density fibre boards, method for production and use thereof |
| CN101259386A (en) * | 2007-12-19 | 2008-09-10 | 天津大学 | Phospholipid modified poly (ether-sulfone) ultrafiltration membrane capable of resisting protein pollution and preparation |
| CN104998550A (en) * | 2015-06-30 | 2015-10-28 | 天津大学 | Anti-pollution ultrafiltration membrane filled with amphiphilic surface modified material with crosslinked hydrophobic segment and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2003000761A1 (en) * | 2001-06-21 | 2003-01-03 | Basf Coatings Ag | Coated medium-density fibre boards, method for production and use thereof |
| CN101259386A (en) * | 2007-12-19 | 2008-09-10 | 天津大学 | Phospholipid modified poly (ether-sulfone) ultrafiltration membrane capable of resisting protein pollution and preparation |
| CN104998550A (en) * | 2015-06-30 | 2015-10-28 | 天津大学 | Anti-pollution ultrafiltration membrane filled with amphiphilic surface modified material with crosslinked hydrophobic segment and preparation method thereof |
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