CN117323835A - Preparation method of microfiltration membrane - Google Patents
Preparation method of microfiltration membrane Download PDFInfo
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- CN117323835A CN117323835A CN202311548477.9A CN202311548477A CN117323835A CN 117323835 A CN117323835 A CN 117323835A CN 202311548477 A CN202311548477 A CN 202311548477A CN 117323835 A CN117323835 A CN 117323835A
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- 239000012528 membrane Substances 0.000 title claims abstract description 82
- 238000001471 micro-filtration Methods 0.000 title claims abstract description 43
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 239000000243 solution Substances 0.000 claims abstract description 45
- 239000002904 solvent Substances 0.000 claims abstract description 24
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229920000642 polymer Polymers 0.000 claims abstract description 17
- 239000000126 substance Substances 0.000 claims abstract description 14
- 238000005191 phase separation Methods 0.000 claims abstract description 9
- 238000001035 drying Methods 0.000 claims abstract description 7
- 239000007864 aqueous solution Substances 0.000 claims abstract description 6
- 238000002791 soaking Methods 0.000 claims abstract description 6
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 5
- 239000012298 atmosphere Substances 0.000 claims abstract description 3
- 238000006243 chemical reaction Methods 0.000 claims abstract description 3
- 238000002156 mixing Methods 0.000 claims abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 16
- 150000003384 small molecules Chemical class 0.000 claims description 16
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 15
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 11
- 238000005345 coagulation Methods 0.000 claims description 9
- 230000015271 coagulation Effects 0.000 claims description 9
- 239000002202 Polyethylene glycol Substances 0.000 claims description 7
- 229920001223 polyethylene glycol Polymers 0.000 claims description 7
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 7
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 7
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 5
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 5
- 239000004695 Polyether sulfone Substances 0.000 claims description 5
- 229920002492 poly(sulfone) Polymers 0.000 claims description 5
- 229920006393 polyether sulfone Polymers 0.000 claims description 5
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Chemical compound CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 claims description 4
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 4
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 claims description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 4
- 241000894006 Bacteria Species 0.000 claims description 3
- 239000002033 PVDF binder Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 244000005700 microbiome Species 0.000 claims description 3
- 150000007524 organic acids Chemical class 0.000 claims description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 3
- 102000004169 proteins and genes Human genes 0.000 claims description 3
- 108090000623 proteins and genes Proteins 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 2
- 235000011054 acetic acid Nutrition 0.000 claims description 2
- 150000001298 alcohols Chemical class 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims description 2
- 235000019253 formic acid Nutrition 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 235000005985 organic acids Nutrition 0.000 claims description 2
- 239000004800 polyvinyl chloride Substances 0.000 claims description 2
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 2
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 2
- 235000019260 propionic acid Nutrition 0.000 claims description 2
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 abstract description 7
- 230000001112 coagulating effect Effects 0.000 abstract 2
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 239000011148 porous material Substances 0.000 description 18
- 238000005266 casting Methods 0.000 description 13
- 238000009826 distribution Methods 0.000 description 9
- 239000007788 liquid Substances 0.000 description 9
- 239000011521 glass Substances 0.000 description 8
- 230000004907 flux Effects 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 230000008878 coupling Effects 0.000 description 5
- 238000010168 coupling process Methods 0.000 description 5
- 238000005859 coupling reaction Methods 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 239000013557 residual solvent Substances 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 229960000074 biopharmaceutical Drugs 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000009295 crossflow filtration Methods 0.000 description 1
- 235000013365 dairy product Nutrition 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 238000005371 permeation separation Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- CMDGQTVYVAKDNA-UHFFFAOYSA-N propane-1,2,3-triol;hydrate Chemical compound O.OCC(O)CO CMDGQTVYVAKDNA-UHFFFAOYSA-N 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
- B01D67/0011—Casting solutions therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- 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
- B01D61/147—Microfiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
- B01D67/0013—Casting processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
- B01D67/0016—Coagulation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/34—Polyvinylidene fluoride
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
- B01D71/68—Polysulfones; Polyethersulfones
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/12—Specific ratios of components used
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/15—Use of additives
- B01D2323/16—Swelling agents
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Dispersion Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Water Supply & Treatment (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention provides a preparation method of a microfiltration membrane, which comprises the following steps: (1) Adding a film-forming polymer into a solvent to prepare a film-forming solution with the mass ratio of 12% -24%, adding 10% -20% of pore-forming agent into the film-forming solution, and fully dissolving; (2) Adding a certain amount of polar small molecular substances into the film forming solution, fully and uniformly mixing, and regulating the viscosity of the film forming solution; (3) Preparing a polymer film-forming solution into a polymer solution film, and exposing the solution film to a steam atmosphere with a certain humidity for steam-induced phase inversion for a certain time; (4) Transferring the solution film subjected to steam-induced phase inversion in the step (3) into a non-solvent coagulating bath, performing non-solvent-induced phase separation film formation, taking out, and continuously storing in a fresh non-solvent coagulating bath for a period of time to enable the phase inversion to be completed; (5) And (3) soaking the membrane with the complete phase conversion in the step (4) in a glycerol aqueous solution for 24 hours, and naturally drying to obtain the microfiltration membrane.
Description
Technical Field
The invention belongs to the technical field of membrane separation, and relates to a preparation method of a separation membrane, in particular to a preparation method of a microfiltration membrane.
Technical Field
Microfiltration membranes, which generally have a pore size greater than 0.1 μm, are useful for separating and filtering microorganisms, bacteria, proteins, cells and other suspended solids in liquids, and are widely used in the fields of water treatment, dairy, biopharmaceutical, food and beverage, and the like, and are generally prepared by Non-solvent-induced phase separation (NIPS) and vapor-induced phase separation (Vapor inducedphase separation, VIPS). VIPS and NIPS coupling (V-NIPS) are new effective methods for preparing microfiltration membranes, i.e., by exposing to a vapor of a certain humidity for a certain period of time to form pores, and then transferring to a coagulation bath to complete the entire phase inversion process.
Chen et al [ Journal of Membrane Science,2004,235 (1-2): 73-86 ] prepared PVDF microfiltration membranes using V-NIPS coupling, wherein the pore size and internal structure of the membrane were adjusted by controlling the exposure time to steam, but the membrane surface layer was converted from the original dense structure to the macroporous structure only when the exposure time was increased to 10 min. Chen et al [ Journal of Applied Polymer Science,2023,140 (34): e54305 ] prepared PVDF-uniform pore membranes with narrow pore size distribution by V-NIPS coupling, but only showed a narrow distribution porous structure on the membrane surface when exposed to air for up to 10 min. Marino et al [ Membranes,2018,8 (3): 71 ] A membrane having a symmetrical bicontinuous structure was prepared by the V-NIPS method, wherein the exposure time to air of a certain humidity had a very significant effect on the membrane structure, the exposure time increased from 2.5min to 7.5min, the pore diameter increased from 0.17 μm to 0.45 μm, and the pure water permeability increased from 1100L/(m) 2 H.bar) to 7900L/(m) 2 H.bar). Therefore, in the existing V-NIPS method for preparing a macroporous microfiltration membrane, the formation of a macroporous structure generally requires a long vapor exposure time (some are as long as 20 min), and then phase inversion film formation is completed in the NIPS method, which brings about a lot of inconveniences to practical production.
Aiming at the problems in the prior art, the invention provides a preparation method of a microfiltration membrane, which prepares a high-performance microfiltration membrane with narrow pore size distribution by adding a non-solvent into a membrane casting solution to pre-gel the membrane casting solution.
Disclosure of Invention
The invention provides a preparation method of a microfiltration membrane, wherein a non-solvent is added into a membrane casting solution to enable the membrane casting solution to be pregelatinized, and the coupling use of non-solvent induced phase separation (NIPS) and Vapor Induced Phase Separation (VIPS) remarkably shortens the vapor exposure time in the membrane preparation process, simplifies the membrane preparation process and obtains the high-performance microfiltration membrane with narrow pore size distribution. Specifically, the aim of the invention is achieved by the following technical scheme:
a method for preparing a microfiltration membrane, comprising the following steps:
(1) Adding a film-forming polymer into a solvent to prepare a film-forming solution with the mass ratio of 12% -24%, adding 10% -20% of a pore-forming agent into the film-forming solution, and fully dissolving the film-forming solution at a certain temperature;
(2) Adding a certain amount of polar small molecular substances into the film forming solution, fully and uniformly mixing, and adjusting the viscosity of the film forming solution;
(3) Preparing a polymer film-forming solution into a polymer solution film, and exposing the solution film to a steam atmosphere with a certain humidity for steam-induced phase inversion for a certain time;
(4) Transferring the solution film subjected to steam-induced phase inversion obtained in the step (3) into a non-solvent coagulation bath, performing non-solvent-induced phase separation to form a film, taking out, and continuously storing in a fresh non-solvent coagulation bath for a period of time to enable the phase inversion to be completed;
(5) And (3) soaking the membrane with complete phase conversion obtained in the step (4) in a glycerol aqueous solution for 24 hours, and naturally drying to obtain the microfiltration membrane.
In the step (1), the film-forming polymer is one or two of polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride and other materials.
The solvent is one or more of N-methylpyrrolidone, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide and the like.
The pore-forming agent is preferably polyethylene glycol and polyvinylpyrrolidone; wherein the molecular weight of polyethylene glycol is 200-20000Da, and the molecular weight of polyvinylpyrrolidone is 5000-1300000Da.
In step (2), the polar small molecule substance is a non-solvent small molecule substance of the film forming polymer, which may be selected from organic alcohols such as methanol, ethanol, propanol, butanol, organic acids such as formic acid, acetic acid, propionic acid, butyric acid, and water, preferably ethanol, acetic acid, water, and the non-solvent small molecule substance is added in an amount of 0.1% -3% of the film forming solution.
In the step (3), the film forming mode of the solution film may be continuous or discontinuous scraping.
In step (3), the relative humidity of the steam used is 70% -100%, and the steam exposure time is 10 seconds-20 minutes.
The invention further relates to the microfiltration membrane prepared by the method, and the microfiltration membrane can be a microfiltration membrane with a substrate, which is prepared by coating a non-woven fabric substrate, or a substrate-free microfiltration membrane, which is prepared by directly coating a release type substrate and then releasing the substrate.
Microfiltration membranes prepared according to the methods of the invention can be used, for example, to isolate or filter microorganisms, bacteria, proteins, cells, and other suspended solids.
The preparation method of the microfiltration membrane of the invention uses non-solvent induced phase separation (NIPS) and Vapor Induced Phase Separation (VIPS) in a coupling way, and the membrane casting solution is pregelatinized by adding the non-solvent into the membrane casting solution, so that the high-performance microfiltration membrane with narrow pore size distribution is prepared, the method obviously shortens the vapor exposure time in the membrane preparation process, and simplifies the membrane preparation process
Drawings
FIG. 1a is a scanning electron micrograph of a microfiltration membrane obtained in comparative example (0 in polar small molecule content) according to the present invention, and FIGS. 1b, 1c and 1d are scanning electron micrographs of microfiltration membranes obtained in examples 1 to 3 (1%, 2% and 3% in polar small molecule content) according to the present invention, respectively, wherein the percentages in the figures represent the polar small molecule content.
FIG. 2 is a graph showing the effect of the content of polar small molecule substances on the pore size distribution of the membrane in the film-forming polymer solutions of comparative examples (0 for polar small molecule content) and examples 1 to 3 (1%, 2% and 3% for polar small molecule content, respectively) (curve a is a comparative example, and curves b, c and d are examples 1, 2 and 3, respectively), wherein the percentages in the graph represent the content of polar small molecule substances.
Detailed Description
The present invention will be described in detail with reference to specific examples for further explanation of the present invention. The examples are given solely for the purpose of illustration and are not to be construed as limitations. Variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.
The reagents and raw materials used in the examples of the present invention are not particularly limited and are commercially available.
The permeation separation performance of the obtained microfiltration membrane was examined as follows:
the osmotic separation performance of the microfiltration membrane was tested using a cross-flow filtration device, wherein the effective membrane area tested was 7.1cm 2 The test pressure was 1bar and the test temperature was 25.+ -. 0.5 ℃.
The water flux is calculated according to the following formula (1):
wherein J is the water flux of the membrane (L.m 2 H), V is the water volume (L) passing through the membrane, A is the membrane effective area (m 2 ) Δt is the permeation time (h).
Example 1
24g of polyethersulfone and 64g of polyethylene glycol (200 daltons) are dissolved in 12g of N, N-dimethylacetamide, acetic acid with the content of 1% is added into the mixture, the mixture is stirred for 8 hours to be fully dissolved to obtain casting solution, and then the casting solution is transferred into a vacuum oven for defoaming for 1 hour for standby. And then uniformly coating the film on a glass plate at a speed of 1500mm/min by an automatic film coater, wherein the thickness of the liquid film is controlled to be 200 mu m. Rapidly transferring the glass plate coated with the liquid film into a closed space with the relative humidity of 70%, and standing for 10 seconds to form a VIPS film; the VIPS-obtained film was then immediately placed in a water coagulation bath for NIPS film formation. The film was removed and immersed in water for 24 hours to remove the residual solvent. Finally, the membrane is soaked in 50% glycerol water solutionAnd (3) naturally drying the solution for 24 hours to obtain the microfiltration membrane. The pore diameter of the obtained membrane is 35nm, and the permeation flux 543L/(m) 2 ·h·bar)。
Example 2
12g of polysulfone and 12g of polyvinylpyrrolidone are dissolved in 76g of N, N-dimethylformamide, 2% ethanol is added into the polysulfone and the polyvinylpyrrolidone, the polysulfone and the polyvinylpyrrolidone are stirred for 8 hours to be fully dissolved to obtain a casting solution, and then the casting solution is transferred into a vacuum oven for defoaming for 1 hour for standby. And then uniformly coating the film on a glass plate at a speed of 1500mm/min by an automatic film coater, wherein the thickness of the liquid film is controlled to be 200 mu m. Rapidly transferring the glass plate coated with the liquid film into a closed space with the relative humidity of 80%, and standing for 20 minutes to form a VIPS film; the VIPS-obtained film was then immediately placed in a water coagulation bath for NIPS film formation. The film was removed and immersed in water for 24 hours to remove the residual solvent. Finally, soaking the membrane in 50% glycerol aqueous solution for 24 hours, and naturally drying to obtain the microfiltration membrane. The pore diameter of the obtained membrane is 50nm, and the permeation flux 1530L/(m) 2 ·h·bar)。
Example 3
18g of polyethersulfone and 70g of polyethylene glycol (400 daltons) are dissolved in 12g of N, N-dimethylacetamide, 3% water is added into the mixture, the mixture is stirred for 8 hours to be fully dissolved to obtain casting solution, and then the casting solution is transferred into a vacuum oven for defoaming for 1 hour for standby. And then uniformly coating the film on a glass plate at a speed of 1500mm/min by an automatic film coater, wherein the thickness of the liquid film is controlled to be 200 mu m. Rapidly transferring the glass plate coated with the liquid film into a closed space with the relative humidity of 100%, and standing for 30 seconds to form a VIPS film; the VIPS-obtained film was then immediately placed in a water coagulation bath for NIPS film formation. The film was removed and immersed in water for 24 hours to remove the residual solvent. Finally, soaking the membrane in 50% glycerol aqueous solution for 24 hours, and naturally drying to obtain the microfiltration membrane. The pore diameter of the obtained membrane is 190nm, and the permeation flux is 4500L/(m) 2 ·h·bar)。
Comparative example 1
18g of polyethersulfone and 70g of polyethylene glycol (400 daltons) are dissolved in 12g of N, N-dimethylacetamide, stirred for 8 hours to be fully dissolved to obtain casting solution, and then transferred into a vacuum oven for deaeration for 1 hour for standby. And then uniformly coating the film on a glass plate at a speed of 1500mm/min by an automatic film coater, wherein the thickness of the liquid film is controlled to be 200 mu m. Will be coated withRapidly transferring the glass plate with the liquid film into a closed space with the relative humidity of 100%, and standing for 30 seconds to form a VIPS film; the VIPS-obtained film was then immediately placed in a water coagulation bath for NIPS film formation. The film was removed and immersed in water for 24 hours to remove the residual solvent. Finally, soaking the membrane in 50% glycerol aqueous solution for 24 hours, and naturally drying to obtain the microfiltration membrane. The pore diameter of the obtained membrane is less than 10nm, and the permeation flux is 15L/(m) 2 ·h·bar)。
FIG. 1 is a scanning electron micrograph of the microfiltration membrane obtained in comparative example (0 in polar small molecule content) and examples 1 to 3 (1%, 2% and 3% in polar small molecule content, respectively); as can be seen from fig. 1, the additive content in the film-forming polymer solution has an effect on the film surface structure.
Fig. 2 shows curves of the influence of the content of the polar small molecular substances on the pore size distribution of the membrane in the film-forming polymer solutions of the comparative example (the content of the polar small molecules is 0) and the examples 1 to 3 (the content of the polar small molecules is 1%, 2% and 3% respectively), wherein the pore size distribution curves of the microfiltration membranes with the content of the polar small molecular substances of 0%, 1%, 2 and 3% are shown in the figure from left to right in the order of 4 curves a, b, c, d, so that the content of the polar small molecular substances has a significant influence on the pore size and the pore size distribution of the membrane, and further influence the separation performance of the permeate flux.
Claims (10)
1. A method for preparing a microfiltration membrane, comprising the following steps:
(1) Adding a film-forming polymer into a solvent to prepare a film-forming solution with the mass ratio of 12% -24%, and adding 10% -20% of pore-forming agent into the film-forming solution to be fully dissolved;
(2) Adding a certain amount of polar small molecular substances into the film forming solution, fully and uniformly mixing, and adjusting the viscosity of the film forming solution;
(3) Preparing a polymer film-forming solution into a polymer solution film, and exposing the solution film to a steam atmosphere with a certain humidity for steam-induced phase inversion for a certain time;
(4) Transferring the solution film subjected to steam-induced phase inversion obtained in the step (3) into a non-solvent coagulation bath, performing non-solvent-induced phase separation to form a film, taking out, and continuously storing in a fresh non-solvent coagulation bath for a period of time to enable the phase inversion to be completed;
(5) And (3) soaking the membrane with complete phase conversion obtained in the step (4) in a glycerol aqueous solution for 24 hours, and naturally drying to obtain the microfiltration membrane.
2. The method for preparing a microfiltration membrane according to claim 1, wherein in the step (1), the film-forming polymer is one or two of polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride and other materials, and the solvent is one or more of N-methylpyrrolidone, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide and other solvents; the pore-forming agent is polyethylene glycol or polyvinylpyrrolidone.
3. The method for preparing a microfiltration membrane according to claim 2 wherein the polyethylene glycol has a molecular weight of 200-20000Da and polyvinylpyrrolidone has a molecular weight of 5000-1300000 daltons.
4. The method for producing a microfiltration membrane according to claim 1, wherein in the step (2), the polar small molecular substance is a non-solvent small molecular substance of a film forming polymer selected from the group consisting of organic alcohols, organic acids, water.
5. The method for preparing a microfiltration membrane according to claim 4 wherein the organic alcohol is methanol, ethanol, propanol, butanol; the organic acid is formic acid, acetic acid, propionic acid or butyric acid.
6. The method for preparing a microfiltration membrane according to claim 4 wherein the polar small molecule substance is ethanol, acetic acid or water.
7. The method for preparing a microfiltration membrane according to any one of claims 1 and 4-6 wherein the polar small molecule is added in an amount of 0.1-3% of the membrane forming solution.
8. The method for producing a microfiltration membrane according to claim 1, wherein in step (3), the relative humidity of the steam is 70% -100% and the steam exposure time is 10 seconds to 20 minutes.
9. A microfiltration membrane prepared according to the method of any one of the preceding claims 1-7.
10. Use of a microfiltration membrane according to claim 9 for separating or filtering microorganisms, bacteria, proteins, cells and suspended solids.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311548477.9A CN117323835A (en) | 2023-11-20 | 2023-11-20 | Preparation method of microfiltration membrane |
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