CN117123071A - Ultrafiltration membrane and preparation method thereof - Google Patents
Ultrafiltration membrane and preparation method thereof Download PDFInfo
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- CN117123071A CN117123071A CN202210553671.5A CN202210553671A CN117123071A CN 117123071 A CN117123071 A CN 117123071A CN 202210553671 A CN202210553671 A CN 202210553671A CN 117123071 A CN117123071 A CN 117123071A
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- 239000012528 membrane Substances 0.000 title claims abstract description 100
- 238000000108 ultra-filtration Methods 0.000 title claims abstract description 82
- 238000002360 preparation method Methods 0.000 title abstract description 19
- 239000010410 layer Substances 0.000 claims abstract description 75
- 239000011148 porous material Substances 0.000 claims abstract description 52
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 45
- 239000002346 layers by function Substances 0.000 claims abstract description 34
- 239000002344 surface layer Substances 0.000 claims abstract description 34
- 239000000758 substrate Substances 0.000 claims abstract description 32
- 238000005266 casting Methods 0.000 claims description 47
- 229920000642 polymer Polymers 0.000 claims description 47
- 238000000889 atomisation Methods 0.000 claims description 43
- 239000002904 solvent Substances 0.000 claims description 40
- 238000000034 method Methods 0.000 claims description 37
- 239000007788 liquid Substances 0.000 claims description 23
- 238000005345 coagulation Methods 0.000 claims description 22
- 230000015271 coagulation Effects 0.000 claims description 22
- 239000003795 chemical substances by application Substances 0.000 claims description 20
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 17
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 14
- 229920000728 polyester Polymers 0.000 claims description 14
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 12
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 12
- 239000004695 Polyether sulfone Substances 0.000 claims description 10
- 229920006393 polyether sulfone Polymers 0.000 claims description 10
- 229920000098 polyolefin Polymers 0.000 claims description 10
- 239000004952 Polyamide Substances 0.000 claims description 8
- 229920002647 polyamide Polymers 0.000 claims description 8
- 239000002033 PVDF binder Substances 0.000 claims description 7
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 7
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 6
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- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 4
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 4
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 229920002125 Sokalan® Polymers 0.000 claims description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 4
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 4
- 229920001893 acrylonitrile styrene Polymers 0.000 claims description 4
- 229920002301 cellulose acetate Polymers 0.000 claims description 4
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 claims description 4
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 229920000747 poly(lactic acid) Polymers 0.000 claims description 4
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- 239000004584 polyacrylic acid Substances 0.000 claims description 4
- 229920001601 polyetherimide Polymers 0.000 claims description 4
- 229920001721 polyimide Polymers 0.000 claims description 4
- 239000004626 polylactic acid Substances 0.000 claims description 4
- 229920002223 polystyrene Polymers 0.000 claims description 4
- 239000004800 polyvinyl chloride Substances 0.000 claims description 4
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 4
- SCUZVMOVTVSBLE-UHFFFAOYSA-N prop-2-enenitrile;styrene Chemical compound C=CC#N.C=CC1=CC=CC=C1 SCUZVMOVTVSBLE-UHFFFAOYSA-N 0.000 claims description 4
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 4
- 238000007790 scraping Methods 0.000 claims description 3
- 229920002050 silicone resin Polymers 0.000 claims description 3
- AVQQQNCBBIEMEU-UHFFFAOYSA-N 1,1,3,3-tetramethylurea Chemical compound CN(C)C(=O)N(C)C AVQQQNCBBIEMEU-UHFFFAOYSA-N 0.000 claims description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 claims description 2
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 2
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- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 2
- 229910021389 graphene Inorganic materials 0.000 claims description 2
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- WEFZXWJJPHGTTN-UHFFFAOYSA-N methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate Chemical compound COC(=O)C(C)CCC(=O)N(C)C WEFZXWJJPHGTTN-UHFFFAOYSA-N 0.000 claims description 2
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims description 2
- 229920001223 polyethylene glycol Polymers 0.000 claims description 2
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- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 2
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 2
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 2
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 claims description 2
- WVLBCYQITXONBZ-UHFFFAOYSA-N trimethyl phosphate Chemical compound COP(=O)(OC)OC WVLBCYQITXONBZ-UHFFFAOYSA-N 0.000 claims description 2
- 239000011592 zinc chloride Substances 0.000 claims description 2
- 235000005074 zinc chloride Nutrition 0.000 claims description 2
- 239000011787 zinc oxide Substances 0.000 claims description 2
- 239000004254 Ammonium phosphate Substances 0.000 claims 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims 1
- 229910000148 ammonium phosphate Inorganic materials 0.000 claims 1
- 235000019289 ammonium phosphates Nutrition 0.000 claims 1
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims 1
- 229920005989 resin Polymers 0.000 claims 1
- 239000011347 resin Substances 0.000 claims 1
- 229910052710 silicon Inorganic materials 0.000 claims 1
- 239000010703 silicon Substances 0.000 claims 1
- 230000004907 flux Effects 0.000 abstract description 19
- 230000014759 maintenance of location Effects 0.000 abstract description 13
- 238000000926 separation method Methods 0.000 abstract description 11
- 239000000243 solution Substances 0.000 description 44
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 10
- 238000005191 phase separation Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 239000008367 deionised water Substances 0.000 description 8
- 229910021641 deionized water Inorganic materials 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 108091003079 Bovine Serum Albumin Proteins 0.000 description 7
- 229940098773 bovine serum albumin Drugs 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 7
- 239000003361 porogen Substances 0.000 description 7
- 239000004745 nonwoven fabric Substances 0.000 description 6
- 230000035699 permeability Effects 0.000 description 5
- 238000012876 topography Methods 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000000706 filtrate Substances 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000001112 coagulating effect Effects 0.000 description 3
- 239000003814 drug Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000004088 foaming agent Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
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- 239000012085 test solution Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 1
- 229920001046 Nanocellulose Polymers 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
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- 238000010041 electrostatic spinning Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
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- 210000002615 epidermis Anatomy 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 238000000713 high-energy ball milling Methods 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000001471 micro-filtration Methods 0.000 description 1
- 238000001728 nano-filtration Methods 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 238000002663 nebulization Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
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- 238000001223 reverse osmosis Methods 0.000 description 1
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Classifications
-
- 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
- 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
- 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
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/10—Supported membranes; Membrane supports
-
- 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
- B01D71/26—Polyalkenes
-
- 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
- B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
- B01D71/42—Polymers of nitriles, e.g. polyacrylonitrile
-
- 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
- B01D71/52—Polyethers
-
- 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
- B01D71/56—Polyamides, e.g. polyester-amides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Dispersion Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to the field of membrane separation, and discloses an ultrafiltration membrane and a preparation method thereof. The ultrafiltration membrane comprises a substrate layer and a functional layer, wherein the functional layer comprises a sub-layer and a surface layer which are sequentially attached to the substrate layer; wherein the average pore diameter of the surface layer is 1-100nm, the sub-layer is of a three-dimensional network porous structure, and the average pore diameter of the sub-layer is 200-500nm; the porosity of the functional layer is 60-90%. The ultrafiltration membrane has high retention rate and water flux, and has simple preparation process and low cost.
Description
Technical Field
The invention relates to the field of membrane separation, in particular to an ultrafiltration membrane and a preparation method thereof.
Background
The demand of modern society for water resources is increasing, and fresh water resources are being more and more threatened and infringed by environmental pollution as a precious resource for our human lives. The membrane separation technology is one of the most promising high and new technologies, and the application fields mainly comprise microfiltration, ultrafiltration, nanofiltration, reverse osmosis and the like. Among them, ultrafiltration has advantages of low energy consumption, simple equipment layout, high separation level, and the like, and is considered as one of the most economical, efficient and clean membrane separation technologies. Besides water treatment and recycling, ultrafiltration technology is widely applied in the fields of biological medicine, food processing and the like.
Report in literature (Journal of Environmental Chemical Engineering 2021,9,105115): cuS prepared by high-energy ball milling technology 2 The nano particles are used as pore-forming agents of PVDF ultrafiltration membranes, so that the pore structure and the porosity of the membranes can be effectively improved, and the water flux of the ultrafiltration membranes can be increased. Literature (Journal of Membrane S)Science 2020,612,118382) report: the high-flux nanofiber ultrafiltration membrane prepared by taking electrospun Polyacrylonitrile (PAN) nanofibers deposited on non-woven fabrics as a supporting layer and taking nanocellulose composite PAN as a epidermis layer has significantly improved permeability. The interpenetrating nanofiber-polymer network formed in the separation layer greatly enhances the mechanical strength of the composite membrane and provides water channels. For the liquid separation membrane, it is known that the membrane preparation efficiency by the electrostatic spinning method is low and the preparation cost is high. In addition, the preparation methods of organic-inorganic hybrid metal net films (as disclosed in CN 110280222), A, film surface chemical grafting (as disclosed in CN 109499393A) and the like are also provided, but the problems of narrow separation application range, complex preparation process, high cost and the like are also provided.
Therefore, it is important to provide a high-performance ultrafiltration membrane which not only can meet the requirement of separation performance of a separation membrane, but also has low price of raw materials, low preparation cost and simple preparation process.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide an ultrafiltration membrane and a preparation method thereof, wherein the ultrafiltration membrane has higher retention rate and water flux, and the preparation process is simple and the cost is lower.
In order to achieve the above object, in one aspect, the present invention provides an ultrafiltration membrane comprising a substrate layer and a functional layer, the functional layer comprising a sub-layer and a surface layer sequentially attached to the substrate layer;
wherein the average pore diameter of the surface layer is 1-100nm, the sub-layer is of a three-dimensional network porous structure, and the average pore diameter of the sub-layer is 200-500nm; the porosity of the functional layer is 60-90%.
The second aspect of the invention provides a method for preparing an ultrafiltration membrane, comprising: adopting a casting solution containing a film-forming polymer, selecting one side of a substrate layer as a film-forming side, forming a film, protecting the film-forming side, atomizing the non-film-forming side of the substrate layer, and immersing the atomized product into a coagulation bath;
wherein the atomization time is 1-60s.
In a third aspect the invention provides an ultrafiltration membrane prepared by the method described above.
Through the technical scheme, the invention has the following beneficial effects:
1. the ultrafiltration membrane provided by the invention has higher rejection rate and water flux. In the conventional technology, the higher retention rate is realized to reduce the water flux, and the higher water flux is realized to reduce the retention rate, so that both the water flux and the retention rate are difficult to be combined. According to the ultrafiltration membrane disclosed by the invention, the pore diameter of the surface layer is smaller, the sub-layers are provided with three-dimensional network porous structures, the pore structures are mutually communicated, and the surface layer and the sub-layers are matched together, so that the mass transfer resistance of the ultrafiltration membrane can be effectively reduced, the permeation flux of the membrane is improved, and the high retention rate, particularly the retention rate of BSA (bovine serum albumin) can be ensured. The ultrafiltration membrane can provide better choice in the fields of water treatment, biology, medicine, energy and the like.
2. When the ultrafiltration membrane is prepared by adopting the method provided by the invention, the effect equivalent to that of adding the pore-foaming agent can be obtained while no additional pore-foaming agent is added, so that the use of the pore-foaming agent can be avoided, and the preparation cost is reduced.
3. The preparation method has the advantages of simple process, safety, high efficiency, easily available raw materials and low cost, and can adopt relatively compact equipment layout when being used for preparation, thereby being more beneficial to industrial production.
Drawings
FIG. 1 is a topography of the surface layer of an ultrafiltration membrane prepared in example 3 of the present invention;
FIG. 2 is a graph showing the morphology of the sub-layer of the ultrafiltration membrane prepared in example 3 of the present invention;
FIG. 3 is a topography of the surface layer of the ultrafiltration membrane prepared in example 4 of the present invention;
FIG. 4 is a graph showing the morphology of the sub-layer of the ultrafiltration membrane prepared in example 4 of the present invention;
FIG. 5 is a topography of the surface layer of the ultrafiltration membrane prepared in example 14 of the present invention;
FIG. 6 is a graph of the morphology of the sublayers of the ultrafiltration membrane prepared in example 14 of the present invention;
FIG. 7 is a topography of the surface layer of the ultrafiltration membrane prepared in comparative example 1 of the present invention;
FIG. 8 is a graph showing the morphology of the sub-layer of the ultrafiltration membrane prepared in comparative example 1 of the present invention.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In a first aspect, the present invention provides an ultrafiltration membrane comprising a substrate layer and a functional layer, the functional layer comprising a sub-layer and a surface layer sequentially attached to the substrate layer;
wherein the average pore diameter of the surface layer is 1-100nm, the sub-layer is of a three-dimensional network porous structure, and the average pore diameter of the sub-layer is 200-500nm; the porosity of the functional layer is 60-90%.
The substrate layer can provide a certain supporting and supporting function for the ultrafiltration membrane. The surface layer and the sublayer are different in structure, the surface layer is provided with uniform holes with narrower pore diameters, solute in the liquid to be treated can be trapped, and the solvent can pass through the surface layer, so that separation of the solvent and the solute is realized. The sublayers have three-dimensional network porous structures, the pores can be communicated with each other, the average pore diameter is larger than that of the surface layer, solute can possibly pass through the sublayers, and the transmission resistance is smaller, so that the water flux can be increased. In the conventional technology, in order to improve the water flux, the functional layer is often required to have larger pore diameter and porosity, but the retention rate is also reduced; in order to increase the retention rate, the functional layer needs to have a smaller pore diameter, but the water flux is obviously reduced, so that the water flux and the retention rate cannot be simultaneously achieved. The inventor of the invention discovers in the research that the ultrafiltration membrane provided by the invention can ensure higher retention rate and obtain higher water permeability.
According to the invention, the porosity of the functional layer is preferably 70-85%.
According to the invention, the average pore size of the sublayers is preferably 220-380nm.
According to the invention, the ultrafiltration membrane preferably has a thickness of 50-400 μm, more preferably 100-260 μm;
according to the present invention, it is preferable that the thickness of the base material layer is 50 to 300 μm, more preferably 70 to 180 μm;
according to the invention, the thickness of the sub-layer is preferably 10-60 μm, more preferably 20-50 μm;
according to the invention, the thickness of the skin layer is preferably 0.5-5 μm, more preferably 1-2.5 μm.
When the above range is satisfied, a higher water permeability can be obtained while ensuring a higher rejection rate.
According to the present invention, it is preferable that the porosity of the base material layer is 20 to 50% and the average pore diameter is 5 to 50. Mu.m. When the above range is satisfied, a higher water permeability and a higher rejection rate can be further ensured.
According to the present invention, the specific material of the substrate layer is not particularly limited, and may be a material commonly used in the art having a certain supporting and supporting function. Preferably, however, the material of the substrate layer is at least one selected from the group consisting of polyesters, polyolefins, polyamides and polyacrylonitriles. For example, it may be a nonwoven fabric of polyester or polyolefin, a woven fabric of polyester or polyolefin, an electrospun film of polyolefin, polyamide, polyester or polyacrylonitrile.
According to the present invention, the material of the functional layer is also preferably not particularly limited, and may be a polymer capable of forming a porous structure, which is commonly used. Preferably, the material of the functional layer is at least one selected from polyvinyl chloride, polysulfone, polyethersulfone, sulfonated polyethersulfone, polyacrylonitrile, cellulose acetate, polyvinylidene fluoride, polyimide, polyacrylic acid, polylactic acid, polyamide, chitosan, polyetherimide, polystyrene, polyolefin, polyester, polytrifluoroethylene, silicone resin and acrylonitrile-styrene copolymer.
In a second aspect, the present invention provides a method for preparing an ultrafiltration membrane, the method comprising: adopting a casting solution containing a film-forming polymer, selecting one side of a substrate layer as a film-forming side, forming a film, protecting the film-forming side, atomizing the non-film-forming side of the substrate layer, and immersing the atomized product into a coagulation bath;
wherein the atomization time is 1-60s.
By adopting the method of protecting the film forming side and then atomizing the non-film forming side of the substrate layer, the film forming side is not directly atomized, the non-film forming side is atomized, atomized liquid can gradually infiltrate into the film forming side from the substrate layer, three-dimensional netlike holes are gradually formed in the structure of the film forming side, when the atomization time is met, the surface layer of the film forming side is basically not influenced, a sub-layer with a three-dimensional netlike porous structure is obtained, the average pore diameter of the sub-layer is larger than that of the surface layer, and the functional layer has more proper porosity.
The ultrafiltration membrane prepared by the method can ensure higher interception rate and higher water permeability.
According to the present invention, the casting solution preferably contains a poor solvent for the film-forming polymer.
According to the present invention, it is preferable that the liquid used for atomization is a poor solvent for the film-forming polymer.
According to the present invention, it is preferable that the liquid used in the coagulation bath is a poor solvent for the film-forming polymer.
During atomization, the poor solvent of the film-forming polymer and the solvent in the casting solution can exchange to some extent, i.e., undergo phase separation, so that pores can be formed in the film. After immersing in the coagulation bath, a sufficiently complete phase separation can be performed to obtain a suitable pore. In addition, the poor solvent of the film-forming polymer is added into the film-casting solution, so that phase separation can be gradually started during film formation, and the atomization time can be saved. According to the above method, phase separation can be gradually performed, and the pore structure formed is more controllable than in a method in which a hard phase separation occurs in a coagulation bath directly.
According to the present invention, it is preferable that the porosity of the base material layer is 20 to 50%, the average pore diameter is 5 to 50 μm, and the thickness of the base material layer is 50 to 300 μm. It will be appreciated that the thickness of the substrate layer does not substantially change before and after the ultrafiltration membrane is prepared.
The materials of the optional substrate layer are described above, and will not be described here again.
The interaction parameter χ, also called Huggins parameter, between the film-forming polymer and the solvent can be used to determine whether the solvent is a poor solvent for the film-forming polymer, generally χ is greater than 0.5, and the solvent can be considered to be a poor solvent for the film-forming polymer. Preferably, the poor solvent for the film-forming polymer is selected from at least one of water, a C1-C5 alcohol, and a C2-C6 ketone. The poor solvent for the film-forming polymer in the coagulation bath used for atomizing in the casting solution may be plural at the same time. For example, an aqueous solution of ethanol having an ethanol concentration of 50 to 110g/L may be used as the liquid used in the atomizing and coagulating bath. Wherein the poor solvent for the film-forming polymer may contain a small amount of an additive, which may be an inorganic salt, or an acid or base, to further promote pore formation, the amount of the additive may be 0.05 to 0.2g relative to 1g of the poor solvent for the film-forming polymer.
According to the present invention, the content of the poor solvent for the film-forming polymer is preferably 0.5 to 5g, more preferably 1.5 to 4g, relative to 100g of the casting solution. Satisfying the above range can further ensure that a relatively gentle phase separation occurs during film formation, and can further save the time of atomization and improve the efficiency.
According to the invention, the concentration of the film-forming polymer in the casting solution is preferably 5 to 30% by weight, preferably 8 to 22% by weight.
According to the present invention, it is preferable that the film-forming polymer in the casting solution is at least one selected from polyvinyl chloride, polysulfone, polyethersulfone, sulfonated polyethersulfone, polyacrylonitrile, cellulose acetate, polyvinylidene fluoride, polyimide, polyacrylic acid, polylactic acid, polyamide, chitosan, polyetherimide, polystyrene, polyolefin, polyester, polytrifluoroethylene, silicone resin and acrylonitrile-styrene copolymer. The film-forming polymer may have a weight average molecular weight of 50-1000kDa.
According to the present invention, the solvent in the casting solution is preferably at least one selected from the group consisting of N, N-dimethylformamide, N-dimethylacetamide, acetone, N-methyl-2-pyrrolidone, dimethylsulfoxide, tetramethylsulfoxide, tetrahydrofuran, dioxane, acetonitrile, chloroform, methyl 5- (dimethylamino) -2-methyl-5-oxopentanoate (which may be a commercially available polarclean solvent), triethyl phosphate, trimethyl phosphate, hexamethylammonium phosphate, tetramethylurea, acetonitrile, toluene, hexane and octane.
The film-forming polymer can be dissolved in the solvent, and after uniform stirring, the poor solvent of the film-forming polymer is added, and after uniform stirring, the film-forming polymer is vacuumized and defoamed. The temperature at which the film-forming polymer is dissolved in the solvent may be specifically selected according to the film-forming polymer and the solvent so as to have a good solubility.
According to the present invention, it is preferable that the casting solution contains a pore-forming agent or does not contain a pore-forming agent, and the content of the pore-forming agent in the casting solution is 0 to 20wt%.
According to the present invention, preferably, the porogen is at least one selected from the group consisting of organic porogens, preferably at least one selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, glycerol, propylene glycol, acetone, polyoxyethylene-polyoxypropylene ether block copolymers, and inorganic porogens, preferably at least one selected from the group consisting of zinc chloride, lithium bromide, carbon nanotubes, graphene oxide, manganese dioxide, silicon dioxide and zinc oxide. The molecular weight of the high molecular weight porogen can be 200-200000Da.
Wherein, for the high molecular type pore-forming agent, the content of the pore-forming agent in the film casting liquid can be 0-20wt%, and for other pore-forming agents, the content of the pore-forming agent in the film casting liquid can be 0-10wt%.
According to a particularly preferred embodiment of the invention, the casting solution does not contain a porogen. By adopting the method provided by the invention, the film with proper pore structure can be obtained without adopting the pore-forming agent, so that the use of the pore-forming agent can be avoided, and the preparation cost is reduced. Moreover, it can be appreciated that the pore-forming agent is generally used for assisting in forming pores during film formation, and the pore-forming agent can flow away after atomization and coagulation bath, so that the prepared ultrafiltration membrane has low pore-forming agent content.
According to the present invention, it is preferable that the film forming method is a doctor blade, and the doctor blade conditions include such a condition that the thickness of the prepared ultrafiltration film is 50 to 400. Mu.m, more preferably 100 to 260. Mu.m. It will be appreciated that the thickness of the membrane is set at the time of scraping and the thickness of the functional layer in the final produced ultrafiltration membrane is somewhat different, and therefore the thickness of the scraped membrane is generally about 50-100 μm higher than the thickness of the functional layer desired to be produced.
The method for protecting the film forming side can be a shielding protection method, an air blowing protection method and the like, wherein the shielding protection method is to protect the functional layer by adopting a shielding box so as to prevent atomized liquid from being directly sprayed onto the surface of the functional layer, and the air blowing protection method is to discharge mild compressed air through an air pipe so as to prevent the atomized liquid from being directly sprayed onto the surface of the functional layer.
According to the present invention, the time for the atomization is preferably 2 to 40s (for example, may be 2s, 5s, 10s, 15s, 20s, 25s, 30s, 35s, 40s and a range formed by any two of the above values), more preferably 5 to 20s.
According to the invention, preferably, the temperature of the atomization is 20-30 ℃.
According to the invention, the atomized droplets preferably have a particle size of 1-50 μm, more preferably 3-30 μm.
According to the invention, it is preferable that the distance relative to 1m 2 The consumption of the liquid for atomization is 2.5 to 20L/h, more preferably 6 to 17L/h.
The particular manner of atomization may be selected as is conventional in the art, such as pressure atomization, rotary disk atomization, ultrasonic atomization, and the like.
When the above range is satisfied, it can be further ensured that a sub-layer having a three-dimensional network-like porous with more appropriate pore size and porosity is obtained without affecting the surface layer.
According to the invention, the temperature of the coagulation bath is preferably 10-40 ℃.
It will be appreciated that the coagulation bath time is generally relatively short and can be completed within 10 seconds.
When the above range is satisfied, it can be further ensured that a more gentle and sufficient phase separation is performed in the coagulation bath, so that the pore structure of the formed sub-layer is more suitable.
According to the invention, preferably, after the coagulation bath, the method further comprises: washing the product after coagulation bath. The washing is to remove the residual solvent.
In a third aspect, the present invention provides an ultrafiltration membrane prepared by the method described above.
The ultrafiltration membrane provided by the invention has higher interception rate and water flux, and can be widely applied to the fields of water treatment, biology, medicine, food, energy sources and the like.
According to a particularly preferred embodiment of the invention, the ultrafiltration membrane is prepared as follows:
a DMF solution of polyacrylonitrile was prepared, wherein the concentration of polyacrylonitrile was 10-13wt%, and the casting solution contained deionized water, with respect to 100g of the casting solution, the water content was 3-3.9g.
The casting solution is coated on a polyester non-woven fabric (the porosity is 30-40% and the average pore diameter is 8-15 μm) with the thickness of 80-90 μm by adopting a continuous film scraping machine.
Protecting film forming side by shielding with shielding box, directing non-film forming side of film after doctor blade coating to liquid drop bath of deionized water ultrasonic atomization, standing for 20-30s at 20-24deg.C, and liquid drop particle diameter of 4-8 μm, relative to 1m 2 The consumption of liquid for atomization is 15-17L/h. Removing a shielding box used for shielding, immersing the atomized product into a deionized water coagulation bath, and carrying out complete phase separation at 20-25 ℃; washing with water to obtain the ultrafiltration membrane.
The present invention will be described in detail by examples. In the examples below, the chemicals used were all commercially available products, and no particular purification treatments were used unless otherwise indicated.
In the following examples:
the method for protecting the film forming side is shielding protection, namely, a shielding box is adopted to protect the functional layer;
immersing in coagulating bath to form film within about 5 s;
the weight average molecular weight of polyacrylonitrile is 85kDa;
the weight average molecular weight of polyvinylidene fluoride is 700kDa;
the weight average molecular weight of polyethersulfone is 70kDa;
spraying equipment: the ultrasonic humidifier is Haoqi HQ-JS130H.
Example 1
A DMF (N, N-dimethylformamide) solution of polyacrylonitrile was prepared, in which the concentration of polyacrylonitrile was 11.76% by weight, and the content of water in the casting solution was 1.96g relative to 100g of the casting solution, which was a poor solvent for the film-forming polymer.
The casting solution was knife-coated on a polyester nonwoven fabric (porosity: 37% and average pore diameter: 9.3 μm) having a thickness of 85 μm using a continuous doctor blade machine.
Protecting film-forming side by shielding with a shielding box, and keeping non-film-forming side of film after doctor blade coating for 20s toward droplet bath of deionized water ultrasonic atomization at 20deg.C with droplet size of 5 μm relative to 1m 2 The consumption of liquid for atomization was 17L/h. Removing a shielding box used for shielding, immersing the atomized product into a deionized water coagulation bath, and carrying out complete phase separation at 20 ℃; washing with water to obtain the ultrafiltration membrane.
Example 2
An ultrafiltration membrane was produced in the same manner as in example 1 except that the amount of water in the casting solution was 2.88g relative to 100g of the casting solution.
Example 3
An ultrafiltration membrane was produced in the same manner as in example 1 except that the amount of water in the casting solution was 3.8g relative to 100g of the casting solution.
Example 4
Ultrafiltration membranes were prepared as in example 1 except that in the atomization, the time of atomization was 15s.
Example 5
Ultrafiltration membranes were prepared as in example 2 except that in the atomization, the time of atomization was 10s.
Example 6
Ultrafiltration membranes were prepared as in example 3 except that in the atomization, the time of atomization was 5s.
Example 7
Ultrafiltration membranes were prepared as in example 3, except that in atomization, the membrane was varied relative to 1m 2 The consumption of liquid for atomization was 6.2L/h.
Example 8
Ultrafiltration membranes were prepared as in example 3, except that in atomization, the membrane was varied relative to 1m 2 The consumption of liquid for atomization was 10L/h.
Example 9
An ultrafiltration membrane was prepared as in example 1, except that the poor solvent for the film-forming polymer in the casting solution was ethanol. The atomizing and coagulating bath was an aqueous ethanol solution having an ethanol concentration of 100 g/L.
Example 10
An ultrafiltration membrane was prepared as in example 1, except that the casting solution was a DMF solution of polyethersulfone having a concentration of 15wt% and the water content was still 1.96g relative to 100g of the casting solution.
The substrate layer is polyester non-woven fabric, the porosity is 22%, the average pore diameter is 20 mu m, the thickness is 150 mu m, the atomization temperature is 25 ℃, and the particle size of atomized liquid drops is 10 mu m; the temperature of the coagulation bath was 18 ℃.
Example 11
An ultrafiltration membrane was prepared as in example 1, except that the casting solution was a DMF solution of polyvinylidene fluoride having a concentration of 8% by weight and the water content was still 1.96g relative to 100g of the casting solution.
The substrate layer is a polyester nonwoven fabric, the porosity is 48%, the average pore diameter is 45 μm, the thickness is 180 μm, the atomization temperature is 30 ℃, the atomized droplet size is 25 μm, the atomization time is 10s, and the temperature of the coagulation bath is 32 ℃.
Example 12
An ultrafiltration membrane was prepared as in example 1, except that the casting solution further contained a content of Kong Jiju vinylpyrrolidone (molecular weight of 58000 Da) in an amount of 0.5% by weight.
Example 13
An ultrafiltration membrane was prepared in the same manner as in example 1 except that the content of the poor solvent of the film-forming polymer was 0.4g relative to 100g of the casting solution, and the time for atomization was 0.5s relative to 1m 2 The consumption of liquid for atomization was 1L/h.
Example 14
An ultrafiltration membrane was prepared as in example 1, except that no poor solvent for the film-forming polymer was added to the casting solution.
Example 15
An ultrafiltration membrane was prepared as in example 9, except that no poor solvent for the film-forming polymer was added to the casting solution.
Comparative example 1
Ultrafiltration membranes were prepared as in example 1 except that no atomization was performed.
Comparative example 2
Ultrafiltration membranes were prepared as in example 1, except that the time to nebulization was 120s.
Test example 1
The following measurements were made on the products prepared in examples and comparative examples, respectively:
the average pore size of the surface layer was determined using a pore size analyzer (GaoQ PSMA-10, available from Nanjing Gao Qian);
and measuring the porosity of the functional layer by adopting a weighing method:
since the total volume of the ultrafiltration membrane is the sum of the total volume of the substrate layer and the total volume of the functional layer, the total volume of the functional layer includes the volume of pores therein and the substantial volume of film-forming polymer. Firstly, determining the volume of the ultrafiltration membrane, and subtracting the total volume of the substrate layer to obtain the total volume of the functional layer; the total weight of the ultrafiltration membrane was then determined, subtracting the total weight of the substrate layer to give the total weight of the functional layer. From the total weight of the functional layer, and the density of the film-forming polymer, the substantial volume of the film-forming polymer can be obtained, and then the substantial volume of the film-forming polymer, i.e., the volume of the pores on the functional layer, is subtracted from the total volume of the functional layer, thereby obtaining the porosity.
Measuring the thickness of the ultrafiltration membrane by using a thickness gauge (purchased from Shanghai LiuLing);
firstly, a scanning electron microscope (model is S-4800, purchased from Hitachi Co., japan) is adopted to obtain an SEM image of an ultrafiltration membrane, then, the appearance of the SEM image is analyzed by adopting Nanomeasure software, and the average pore diameter of a sub-layer, the thickness of the sub-layer and the thickness of a surface layer are measured;
determination of water flux:
immersing the ultrafiltration membrane in deionized water, measuring for 1h under the conditions that the operating pressure is 0.1MPa (the pressure of flowing water is controlled by a pressure gauge) and the water temperature is 25 ℃, accurately measuring the volume of deionized water passing through the ultrafiltration membrane, and calculating to obtain the pure water flux J by the following formula:
J＝V/(S·t)
wherein J represents the pure water flux (L/m of the ultrafiltration membrane 2 h) V represents the volume (L) of the filtrate, S represents the effective area (m 2 ) T represents the time (h) taken to reach the volume V of the filtrate.
Determination of the rejection rate:
at an operating pressure of 0.1MPa, at a temperature of 25℃of 0.1 g.L -1 As a test solution, an aqueous solution of Bovine Serum Albumin (BSA) having a molecular weight of 67kDa was used, and an ultrafiltration membrane was immersed in the BSA solution to carry out a retention test. After the filtrate was collected at room temperature, absorbance A of the BSA test solution and the filtrate was measured by a UV grating spectrophotometer at a wavelength of 280nm, and the rejection rate of BSA by the ultrafiltration membrane was calculated by the formula.
The results are shown in tables 1-2.
TABLE 1
TABLE 2
The result shows that the ultrafiltration membrane prepared by the method provided by the invention has higher retention rate and water flux. It can be seen from examples 1-3 and 14 that the pore structure of the membrane can be improved by adopting the poor solvent of the membrane-forming polymer to regulate and control the membrane-casting solution, the membrane flux is improved, and the pore diameter and the porosity of the membrane are increased and the pure water flux is correspondingly increased along with the increase of the addition amount of deionized water in the membrane-casting solution.
The films prepared in the above examples and comparative examples were observed by a scanning electron microscope (SEM, S-4800, hitachi Co., japan), respectively, and the structures of the surface layer and the sub-layer of the films were observed.
The morphology of the surface layer of the membrane prepared in the example 3 is shown in the figure 1, and the pore size distribution of the surface layer is narrow, and the membrane has no crack and macroporous defect, and uniform and regular pores; in the direction perpendicular to the membrane plane, the cross-sectional structure of the sub-layers is shown in fig. 2, and it can be seen that the sub-layers have interconnected three-dimensional network porous structures, and the types of the pores are uniform.
The film prepared in example 4 has the morphology of the surface layer and the cross-sectional structure of the sublayers in the direction perpendicular to the plane of the film as shown in fig. 3-4, respectively. As can be seen from the figure, the membrane prepared in example 4 is similar to the membrane prepared in example 3, the pore diameter of the surface layer is narrower, no crack or macropore defect exists, and the pores are uniform and regular; the sub-layer is provided with a three-dimensional network porous structure which is mutually communicated, and the types of the holes are consistent.
The films prepared in example 14 are shown in FIGS. 5-6, respectively, for the topography of the surface layer and the cross-sectional structure of the sublayers in the direction perpendicular to the plane of the film. From the graphs and tables of example 14 and example 4, it can be seen that the surface layer and the sub-layer have similar morphology, and it is demonstrated that in the case where the casting solution contains a poor solvent for the film-forming polymer, the poor solvent for the film-forming polymer can be obtained in a shorter atomization time, and the effect in the case where the atomization time is longer, that is, in the case where the casting solution contains the film-forming polymer, the atomization time can be saved, and the preparation efficiency can be improved. The morphology of the surface and sub-layers in examples 9 and 15 are also similar, and also demonstrate that the time to misting can be saved when the casting solution contains poor solvents for the film-forming polymer.
The film prepared in comparative example 1 has the morphology of the surface layer and the cross-sectional structure of the sub-layer in the direction perpendicular to the plane of the film as shown in FIGS. 7 to 8, respectively. The method of comparative example 1, in which the coagulation bath (conventional non-solvent induced phase separation method, also referred to as NIPS) was directly conducted, was found to have a thin and dense sponge-like pore structure above the sublayer (side close to the surface layer), and a finger-like pore structure with poor degree of communication between the sublayer and the sublayer (side close to the base material layer), was significantly different from the sublayer prepared in example "having a three-dimensional network porous structure with mutual communication, and a uniform pore type".
In addition, the pore size of the surface layer of the product prepared by the other examples is narrower, the sub-layers have interconnected three-dimensional network porous structures, and the pore types are consistent (related figures are not shown).
It can also be seen from examples 1 and 12 that the method provided by the invention can obtain the effect equivalent to that of adding the porogen without adding the porogen additionally.
In addition, the preparation process is simple, safe and efficient, and is more beneficial to industrial production.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (12)
1. The ultrafiltration membrane is characterized by comprising a substrate layer and a functional layer, wherein the functional layer comprises a sub-layer and a surface layer which are sequentially attached to the substrate layer;
wherein the average pore diameter of the surface layer is 1-100nm, the sub-layer is of a three-dimensional network porous structure, and the average pore diameter of the sub-layer is 200-500nm; the porosity of the functional layer is 60-90%.
2. The ultrafiltration membrane of claim 1 wherein the functional layer has a porosity of 70-85%;
and/or the average pore diameter of the sub-layer is 220-380nm;
and/or the ultrafiltration membrane has a thickness of 50-400 μm, more preferably 100-260 μm;
and/or the thickness of the substrate layer is 50 to 300 μm, more preferably 70 to 180 μm;
and/or the thickness of the sub-layer is 10-60 μm, more preferably 20-50 μm;
and/or the thickness of the surface layer is 0.5-5 μm, more preferably 1-2.5 μm.
3. Ultrafiltration membrane according to claim 1 or 2, wherein the porosity of the substrate layer is 20-50% and the average pore size is 5-50 μm.
4. An ultrafiltration membrane according to claim 3 wherein the material of the substrate layer is selected from at least one of polyester, polyolefin, polyamide and polyacrylonitrile.
5. The ultrafiltration membrane according to claim 1 or 2 wherein the material of the functional layer is selected from at least one of polyvinyl chloride, polysulfone, polyethersulfone, sulfonated polyethersulfone, polyacrylonitrile, cellulose acetate, polyvinylidene fluoride, polyimide, polyacrylic acid, polylactic acid, polyamide, chitosan, polyetherimide, polystyrene, polyolefin, polyester, polytrifluoroethylene, silicone resin and acrylonitrile-styrene copolymer.
6. A method for preparing an ultrafiltration membrane, the method comprising: adopting a casting solution containing a film-forming polymer, selecting one side of a substrate layer as a film-forming side, forming a film, protecting the film-forming side, atomizing the non-film-forming side of the substrate layer, and immersing the atomized product into a coagulation bath;
wherein the atomization time is 1-60s.
7. The method according to claim 6, wherein the casting solution contains a poor solvent for the film-forming polymer;
and/or the liquid used for atomization is a poor solvent for the film-forming polymer;
and/or the liquid used in the coagulation bath is a poor solvent for the film-forming polymer;
and/or the porosity of the substrate layer is 20-50%, the average pore diameter is 5-50 μm, and the thickness of the substrate layer is 50-300 μm;
and/or the material of the substrate layer is at least one selected from polyester, polyolefin, polyamide and polyacrylonitrile;
and/or the poor solvent of the film-forming polymer is selected from at least one of water, a C1-C5 alcohol, and a C2-C6 ketone;
the content of the poor solvent for the film-forming polymer is preferably 0.5 to 5g, more preferably 1.5 to 4g, relative to 100g of the casting solution.
8. A method according to claim 6 or 7, wherein the concentration of film-forming polymer in the casting solution is 5-30wt%, preferably 8-22wt%;
and/or the film-forming polymer in the casting film liquid is selected from at least one of polyvinyl chloride, polysulfone, polyethersulfone, sulfonated polyethersulfone, polyacrylonitrile, cellulose acetate, polyvinylidene fluoride, polyimide, polyacrylic acid, polylactic acid, polyamide, chitosan, polyetherimide, polystyrene, polyolefin, polyester, polytrifluoroethylene, organic silicon resin and acrylonitrile-styrene copolymer;
and/or the solvent in the casting solution is at least one selected from N, N-dimethylformamide, N-dimethylacetamide, acetone, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetramethyl sulfoxide, tetrahydrofuran, dioxane, acetonitrile, chloroform, 5- (dimethylamino) -2-methyl-5-oxopentanoic acid methyl ester, triethyl phosphate, trimethyl phosphate, hexamethyl ammonium phosphate, tetramethyl urea, acetonitrile, toluene, hexane and octane.
9. The method according to claim 6 or 7, wherein the casting solution contains or does not contain a pore-forming agent, and the content of the pore-forming agent in the casting solution is 0-20wt%;
preferably, the pore-forming agent is at least one selected from organic pore-forming agents and inorganic pore-forming agents, the organic pore-forming agents are preferably at least one selected from polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, glycerol, propylene glycol, acetone, polyoxyethylene-polyoxypropylene ether block copolymers, and the inorganic pore-forming agents are preferably at least one selected from zinc chloride, lithium bromide, carbon nanotubes, graphene oxide, manganese dioxide, silicon dioxide and zinc oxide.
10. A method according to claim 6 or 7, wherein the film forming method is a film scraping method, the conditions of which include making the thickness of the prepared ultrafiltration film 50-400 μm, more preferably 100-260 μm;
and/or, the atomization time is 2-40s;
and/or, the atomization temperature is 20-30 ℃;
and/or the atomized droplets have a particle size of 1-50 μm, preferably 3-30 μm;
and/or, relative to 1m 2 The consumption of liquid for atomization is 2.5 to 20L/h, preferably 6 to 17L/h.
11. The method of claim 6, wherein the coagulation bath has a temperature of 10-40 ℃;
and/or, after the coagulation bath, the method further comprises: washing the product after coagulation bath.
12. An ultrafiltration membrane prepared by the method of any one of claims 6-11.
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