CN115350603A - Polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and preparation method thereof - Google Patents
Polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and preparation method thereof Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 114
- 239000002033 PVDF binder Substances 0.000 title claims abstract description 68
- 229920002981 polyvinylidene fluoride Polymers 0.000 title claims abstract description 68
- 238000001728 nano-filtration Methods 0.000 title claims abstract description 63
- 239000002131 composite material Substances 0.000 title claims abstract description 47
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 238000012695 Interfacial polymerization Methods 0.000 claims abstract description 20
- 239000004952 Polyamide Substances 0.000 claims abstract description 20
- 229920002647 polyamide Polymers 0.000 claims abstract description 20
- 238000000926 separation method Methods 0.000 claims abstract description 10
- 238000007654 immersion Methods 0.000 claims abstract description 8
- 238000000614 phase inversion technique Methods 0.000 claims abstract description 8
- 238000001556 precipitation Methods 0.000 claims abstract description 8
- UUORTJUPDJJXST-UHFFFAOYSA-N n-(2-hydroxyethyl)prop-2-enamide Chemical compound OCCNC(=O)C=C UUORTJUPDJJXST-UHFFFAOYSA-N 0.000 claims abstract description 5
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 20
- 239000000178 monomer Substances 0.000 claims description 19
- 229920000642 polymer Polymers 0.000 claims description 18
- 230000008569 process Effects 0.000 claims description 17
- 239000003607 modifier Substances 0.000 claims description 16
- 239000000243 solution Substances 0.000 claims description 16
- 239000004745 nonwoven fabric Substances 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 11
- 239000012074 organic phase Substances 0.000 claims description 10
- 239000002904 solvent Substances 0.000 claims description 10
- 239000000654 additive Substances 0.000 claims description 8
- 230000000996 additive effect Effects 0.000 claims description 8
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 229920001400 block copolymer Polymers 0.000 claims description 5
- MJYFYGVCLHNRKB-UHFFFAOYSA-N 1,1,2-trifluoroethyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OC(F)(F)CF MJYFYGVCLHNRKB-UHFFFAOYSA-N 0.000 claims description 4
- 239000008346 aqueous phase Substances 0.000 claims description 4
- UWCPYKQBIPYOLX-UHFFFAOYSA-N benzene-1,3,5-tricarbonyl chloride Chemical compound ClC(=O)C1=CC(C(Cl)=O)=CC(C(Cl)=O)=C1 UWCPYKQBIPYOLX-UHFFFAOYSA-N 0.000 claims description 4
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 4
- 229920005604 random copolymer Polymers 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- 229920000587 hyperbranched polymer Polymers 0.000 claims description 3
- GEYOCULIXLDCMW-UHFFFAOYSA-N 1,2-phenylenediamine Chemical compound NC1=CC=CC=C1N GEYOCULIXLDCMW-UHFFFAOYSA-N 0.000 claims description 2
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 claims description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 2
- 239000004215 Carbon black (E152) Substances 0.000 claims description 2
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- 239000002202 Polyethylene glycol Substances 0.000 claims description 2
- 229920002873 Polyethylenimine Polymers 0.000 claims description 2
- 239000004743 Polypropylene Substances 0.000 claims description 2
- FDQSRULYDNDXQB-UHFFFAOYSA-N benzene-1,3-dicarbonyl chloride Chemical compound ClC(=O)C1=CC=CC(C(Cl)=O)=C1 FDQSRULYDNDXQB-UHFFFAOYSA-N 0.000 claims description 2
- 229930195733 hydrocarbon Natural products 0.000 claims description 2
- 150000002430 hydrocarbons Chemical class 0.000 claims description 2
- 229920001600 hydrophobic polymer Polymers 0.000 claims description 2
- 229940018564 m-phenylenediamine Drugs 0.000 claims description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 2
- 229960005141 piperazine Drugs 0.000 claims description 2
- 150000004885 piperazines Chemical class 0.000 claims description 2
- 229920000728 polyester Polymers 0.000 claims description 2
- 229920001223 polyethylene glycol Polymers 0.000 claims description 2
- -1 polypropylene Polymers 0.000 claims description 2
- 229920001155 polypropylene Polymers 0.000 claims description 2
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 2
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 2
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 2
- 229940066771 systemic antihistamines piperazine derivative Drugs 0.000 claims description 2
- LXEJRKJRKIFVNY-UHFFFAOYSA-N terephthaloyl chloride Chemical compound ClC(=O)C1=CC=C(C(Cl)=O)C=C1 LXEJRKJRKIFVNY-UHFFFAOYSA-N 0.000 claims description 2
- 239000003759 ester based solvent Substances 0.000 claims 1
- 239000004210 ether based solvent Substances 0.000 claims 1
- 239000011148 porous material Substances 0.000 abstract description 6
- 230000003204 osmotic effect Effects 0.000 abstract description 3
- 238000005457 optimization Methods 0.000 abstract description 2
- 239000012071 phase Substances 0.000 description 8
- 239000002585 base Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 230000009286 beneficial effect Effects 0.000 description 5
- 230000004907 flux Effects 0.000 description 5
- 230000002209 hydrophobic effect Effects 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- 238000000108 ultra-filtration Methods 0.000 description 5
- 239000004695 Polyether sulfone Substances 0.000 description 4
- 229920002492 poly(sulfone) Polymers 0.000 description 4
- 229920006393 polyether sulfone Polymers 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000001471 micro-filtration Methods 0.000 description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 2
- 229920001721 polyimide Polymers 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 241000282414 Homo sapiens Species 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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- 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
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
-
- 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
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- 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
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/122—Separate manufacturing of ultra-thin membranes
-
- 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
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
-
- 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
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- 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
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/30—Cross-linking
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/50—Control of the membrane preparation process
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/30—Chemical resistance
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
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- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to a polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and a preparation method thereof, belonging to the technical field of separation membranes. The invention provides a polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and a preparation method thereof. The preparation method comprises the following steps: firstly, preparing a polyvinylidene fluoride support membrane with a hydrophilic poly (N-hydroxyethyl acrylamide) (PHEAA) surface functionalized by using an immersion precipitation phase inversion method, and then preparing a polyamide composite nanofiltration membrane by interfacial polymerization. The composite nanofiltration membrane prepared by the invention has excellent osmotic selectivity and stability. The preparation method can regulate and control the porosity, the pore size and the hydrophilicity of the surface of the polyvinylidene fluoride support membrane, further optimizes the interfacial polymerization condition, can realize the optimization of the structure and the performance of the polyamide composite nanofiltration membrane, has controllable preparation process, mature technology and low cost, and has great industrial application prospect.
Description
The technical field is as follows:
the invention belongs to the technical field of separation membranes, and relates to a polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and a preparation method thereof.
The background art comprises the following steps:
with the industrialization process and population growth, water resource shortage and pollution become problems which need to be solved urgently for human beings. The aperture of the nanofiltration membrane is between 0.5 and 1nm, and the nanofiltration membrane has excellent interception capability on multivalent salt and organic small molecules (the molecular weight is between 200 and 1000 Da); therefore, nanofiltration membranes are widely used in the fields of seawater desalination, industrial wastewater, food, medicine, and the like. At present, commercial thin-layer composite polyamide nanofiltration membranes are mainly prepared on the surface of a polysulfone or polyethersulfone base membrane through interfacial polymerization between piperazine and trimesoyl chloride. The traditional polysulfone or polyether sulfone-based membrane has poor surface hydrophilicity and low porosity, and is difficult to overcome the 'trade-off' effect between the inherent solvent permeability and solute selectivity of the thin-layer composite polyamide nanofiltration membrane; in addition, polysulfone and polyether sulfone membranes are easy to swell in ester and ketone organic solvents, and the thin-layer composite polyamide nanofiltration membrane has poor organic solvent resistance stability, so that the application field of the thin-layer composite polyamide nanofiltration membrane is limited.
The thin polyamide layer determines the performance of the polyamide composite nanofiltration membrane, and researches show that the physicochemical properties (aperture size, aperture distribution, surface charge property, hydrophilicity and hydrophobicity and the like) of the ultrafiltration substrate have important influence on the formation of a separation layer in the interfacial polymerization process. The polyvinylidene fluoride membrane has excellent mechanical properties, solvent resistance, acid and alkali resistance and the like, and is widely used as a membrane material for ultrafiltration and microfiltration, however, the membrane prepared by taking a polyvinylidene fluoride ultrafiltration membrane as a substrate has few related reports, because the surface of the polyvinylidene fluoride membrane is not beneficial to uniform dispersion and infiltration of water phase monomers in an interfacial polymerization process, and the pore diameter of the polyvinylidene fluoride membrane subjected to phase transformation is larger than that of polysulfone and polyether sulfone, so that a continuous and flawless polyamide selective separation layer is difficult to prepare, and the development of the polyvinylidene fluoride thin-layer composite nanofiltration membrane is limited.
The invention content is as follows:
in view of the above-mentioned deficiencies of the prior art, the present invention is directed to: provides a thin-layer composite nanofiltration membrane taking a poly (N-hydroxyethyl acrylamide) (PHEAA) surface functionalized polyvinylidene fluoride blend membrane as a substrate. The composite nanofiltration membrane prepared by the method has excellent osmotic selectivity and good organic solvent resistance.
In order to realize the aim, the invention provides a polyvinylidene fluoride-based thin-layer composite nanofiltration membrane. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane consists of a hydrophilic polyvinylidene fluoride support membrane and a polyamide selective separation layer.
The invention provides a hydrophilic polyvinylidene fluoride support membrane in a first aspect. The method comprises the steps of taking amphiphilic polymer of PHEAA as a modifier and polyvinylidene fluoride as a film forming material, adding an additive, and preparing a hydrophilic polyvinylidene fluoride support film on the surface of non-woven fabric by using an immersion precipitation phase inversion method.
Preferably, the monomers corresponding to the hydrophobic polymer structural units in the hydrophilic PHEAA amphiphilic polymer are: one or more of methyl (meth) acrylate (MMA), trifluoroethyl (meth) acrylate (TFEMA), styrene (St) and the like.
Preferably, the amphiphilic polymer of the hydrophilic PHEAA is one or a mixture of block copolymer, hyperbranched polymer and random copolymer. The weight of the amphiphilic polymer additive of the PHEAA is 2-40% of that of the polyvinylidene fluoride.
Preferably, the additive is one or a mixture of polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, lithium chloride and the like. The non-woven fabric is one or a mixture of more of polyester non-woven fabric, polypropylene non-woven fabric and polyamide non-woven fabric.
In the second aspect of the invention, the hydrophilic polyvinylidene fluoride support membrane in the first aspect is used as a substrate to prepare the composite nanofiltration membrane. The method comprises the following specific steps:
(1) Coating a layer of water-soluble monomer aqueous solution on the surface of a hydrophilic polyvinylidene fluoride support membrane, contacting for 20-300 s, removing the water-soluble monomer solution on the surface of the support membrane,
(2) Then a layer of organic phase solution of oil-soluble monomer is coated, after reaction for 20-120 s, the unreacted organic phase solution is removed,
(3) Treating for 5-60 min in an oven at 50-80 ℃.
Preferably, the water-soluble monomer is one or a mixture of more of piperazine, piperazine derivatives, m-phenylenediamine, phenylenediamine and polyethyleneimine. The mass percent of the water-soluble monomer aqueous phase solution is 0.05-1.5%.
Preferably, the oil-soluble monomer is trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride. The mass percentage of the oil-soluble monomer organic phase solution is 0.05-0.2%. The solvent of the organic phase solution is one or a mixture of ester solvent, hydrocarbon solvent or ether solvent.
In the preparation method, the PHEAA surface functionalized polyvinylidene fluoride support membrane is prepared by using an immersion precipitation phase inversion method. Polyvinylidene fluoride has excellent mechanical properties, solvent resistance, acid and alkali resistance and the like, and is widely used as a membrane material for ultrafiltration and microfiltration. And then preparing the polyvinylidene fluoride polyamide composite nanofiltration membrane through interfacial polymerization. In the interfacial polymerization process, the PHEAA chain segment is beneficial to the uniform and high-concentration dispersion of the water-phase monomer piperazine on the surface of the membrane, and the high-permeability and selectivity polyamide composite nanofiltration membrane is prepared after the interfacial polymerization.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the amphiphilic polymer of PHEAA is used as a modifier, polyvinylidene fluoride is used as a film forming material, and the hydrophilic polyvinylidene fluoride support film is prepared on the surface of non-woven fabric by adding the amphiphilic polymer modifier of PHEAA and utilizing an immersion precipitation phase inversion method. The introduction of the modifier can regulate and control the porosity, the pore size and the hydrophilicity of the surface of the polyvinylidene fluoride support membrane. Then, the composite nanofiltration membrane is prepared by taking the hydrophilic polyvinylidene fluoride support membrane as a substrate, and in the interfacial polymerization process, the PHEAA chain segment on the membrane surface is beneficial to uniform and high-concentration dispersion of water-phase monomer piperazine on the membrane surface, so that the prepared polyamide composite nanofiltration membrane has higher crosslinking degree. The composite nanofiltration membrane prepared by the invention has excellent osmotic selectivity and stability. The preparation method can regulate and control the porosity, the pore size and the hydrophilicity of the surface of the polyvinylidene fluoride support membrane, further optimizes the interfacial polymerization condition, can realize the optimization of the structure and the performance of the polyamide composite nanofiltration membrane, has controllable preparation process, mature technology and low cost, and has great industrial application prospect.
The optimized composite nanofiltration membrane has high water permeation flux and very high rejection rate (Na) to divalent salt 2 SO 4 ：99.2％，MgSO 1 : 99.1%), which has wide application prospect in water purification, special material separation and other industries.
Description of the drawings:
FIG. 1 is an electron microscope image of a nanofiltration membrane based on a block copolymer poly (N-hydroxyethyl acrylamide) (PHEAA) modified hydrophilic polyvinylidene fluoride support membrane in example 1 of the present invention, with a scale of 2 μm;
FIG. 2 is an electron microscope image of a nanofiltration membrane based on a hyperbranched PHEAA-modified hydrophilic polyvinylidene fluoride support membrane in example 4 of the present invention, with a scale of 2 μm;
FIG. 3 is an electron microscope image of the nanofiltration membrane based on the random copolymer PHEAA modified hydrophilic polyvinylidene fluoride support membrane of example 7, with a scale of 2 μm;
the specific implementation mode is as follows:
the present experiment will be described in detail below with reference to specific examples for achieving the object of the present invention, but the present invention is not limited to the following examples.
The invention adopts a cross-flow membrane permeation selective separation performance tester to test the membrane separation performance. The effective area of the membrane pool is 7.1cm 2 . Throughout the experiment, the operating pressure was 0.6MPa, the feed temperature was maintained at 25 ℃ and the feed solution was 1000ppm sodium sulfate (Na) 2 SO 4 ) And magnesium sulfate (MgSO) 4 ) And (3) solution. Wherein, prepressing for 1h before testing, and then testing.
Example 1:
the preparation method of the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises the following steps:
s1, selecting a poly (N-hydroxyethyl acrylamide) (PHEAA) functional modifier, wherein a hydrophilic chain segment is PHEAA, a hydrophobic chain segment is polymethyl (meth) acrylate (PMMA), and a polymer structure is a block copolymer.
S2, preparing a hydrophilic polyvinylidene fluoride support film on the surface of the non-woven fabric by using a PHEAA functional modifier through an immersion precipitation phase inversion method, wherein the mass of a PHEAA functional modifier additive accounts for 10% of the mass fraction of the polyvinylidene fluoride.
And S3, pouring 1.0wt% of piperazine aqueous solution on the surface of the prepared hydrophilic polyvinylidene fluoride support membrane, reacting for 1min, and then removing the redundant piperazine aqueous solution on the surface of the surface membrane. Then 0.15wt% of trimesoyl chloride organic phase solution is poured on the surface of the membrane for reaction for 1min, the redundant organic phase solution is poured off, washed by normal hexane, dried and then placed in a 60 ℃ oven for 10min. Taking out and putting into water for later use.
Examples 2 to 3:
the difference from example 1 is that: in the step S1, the PHEAA functional modifier has different hydrophobic segment polymers, the specific parameters are shown in table 1, and the others are the same as those in example 1 and are not repeated herein.
Examples 4 to 6:
the difference from example 1 is that: in the PHEAA functional modifier of step S1, the hydrophobic segment polymer and the polymer structure are different, the specific parameters are shown in table 1, and the others are the same as those in example 1 and are not repeated herein.
Examples 7 to 9:
the difference from example 1 is that: in the PHEAA functional modifier of step S1, the hydrophobic segment polymer and the polymer structure are different, the specific parameters are shown in table 1, and the others are the same as those in example 1 and are not repeated herein.
Table 1 shows the process and performance parameters for examples 1-9
In the interfacial polymerization process, the physicochemical properties (pore size, pore size distribution, surface charge property, hydrophilicity and hydrophobicity and the like) of the ultrafiltration base membrane have important influence on the formation of a polyamide layer in the interfacial polymerization process. The introduction of the PHEAA functional modifier can change the physicochemical property of the base membrane, and the types of the hydrophilic chain segment and the hydrophobic chain segment in the modifier and the type of the polymer can greatly influence the base membrane, which can also influence the performance of the prepared nanofiltration membrane.
Effect of polymer structure on nanofiltration membrane performance: in the process of the immersion precipitation phase inversion method, the block copolymer and the random copolymer are easy to segregate to the surface of the membrane, so that the aperture of the base membrane is increased, the flux of the nanofiltration membrane is increased, the segregation capability of the hyperbranched polymer is weak, the aperture of the base membrane is small, and the flux of the nanofiltration membrane is reduced.
Examples 10 to 14:
the difference from example 1 is that: in the step S2, in the process of preparing the hydrophilic polyvinylidene fluoride support film, the mass fractions of the functional modifier additive of PHEAA in the polyvinylidene fluoride are different, and in the step S3, in the interfacial polymerization process, the concentrations of the water-phase PIP and the oil-phase TMC are different, the specific parameters are shown in table 2, and the others are the same as those in example 1, and are not described herein again.
Table 2 shows the process and performance parameters of examples 1 and 10-14
During interfacial polymerization, PIP diffuses from the aqueous phase to the oil phase and reacts rapidly with TMC in the oil phase to form a polyimide layer on the support film, and therefore, variations in PIP and TMC concentrations have a great influence on the formation of the polyimide layer.
In the invention, the influence of PIP or TMC concentration on the performance of the nanofiltration membrane is as follows: the higher the PIP or TMC concentration is, the more dense the nanofiltration membrane polyamide layer is prepared, the higher the salt rejection rate is and the lower the water flux is. The PHEAA modifier accounts for the mass fraction of PVDF and mainly affects the base membrane, when the PHEAA modifier is increased, the viscosity of PVDF casting membrane liquid is increased, the exchange rate of a non-solvent and a solvent is slowed down in the process of an immersion precipitation phase inversion method, a macroporous structure is easily formed, the aperture of a hydrophilic PVDF support membrane is increased, the prepared nanofiltration membrane polyamide layer is easy to generate defects, the water flux is increased, and the salt rejection rate is reduced.
Examples 15 to 20:
the difference from example 1 is that: in the interfacial polymerization process in step S3, the soaking time of the aqueous solution, the interfacial polymerization time, the heat treatment temperature and the time are different, specific parameters are shown in table 3, and the others are the same as those in example 1 and are not described herein again.
Table 3 shows the process and performance parameters of examples 1 and 15-20
In the invention, the influence of the interfacial polymerization process parameters on the performance of the nanofiltration membrane is as follows: along with the increase of the soaking time of the aqueous phase solution and the interfacial polymerization time, the PIP and TMC react more fully, which is beneficial to improving the separation performance of the nanofiltration membrane, but the reaction time is not too long; the effect of the heat treatment time and the heat treatment temperature on the nanofiltration membrane is not very large.
Claims (9)
1. The polyvinylidene fluoride thin-layer composite nanofiltration membrane and the preparation method thereof are characterized in that: the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane consists of a hydrophilic polyvinylidene fluoride supporting membrane and a polyamide selective separation layer, and the preparation method of the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises the following steps:
(a) Preparing a hydrophilic polyvinylidene fluoride supporting membrane on the surface of non-woven fabric by adding an additive and utilizing an immersion precipitation phase inversion method by taking an amphiphilic polymer containing hydrophilic poly (N-hydroxyethyl acrylamide) (PHEAA) as a modifier and polyvinylidene fluoride as a membrane forming material;
(b) Preparing a polyvinylidene fluoride-based thin-layer composite nanofiltration membrane on the surface of a hydrophilic polyvinylidene fluoride support membrane through interfacial polymerization, wherein the interfacial polymerization process comprises the following steps: coating a layer of water-soluble monomer aqueous solution on the surface of a hydrophilic polyvinylidene fluoride support membrane, contacting for 20-300 s, removing the water-soluble monomer solution on the surface of the support membrane, coating a layer of oil-soluble monomer organic phase solution, reacting for 20-120 s, removing the unreacted organic phase solution, and treating at 50-80 ℃ for 5-60 min to obtain the polyvinylidene fluoride thin-layer composite nanofiltration membrane.
2. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and the preparation method thereof according to claim 1, wherein the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises the following components in parts by weight: in the step a), the monomers corresponding to the hydrophobic polymer structural unit in the hydrophilic PHEAA amphiphilic polymer are as follows: one or more of methyl (meth) acrylate (MMA), trifluoroethyl (meth) acrylate (TFEMA), styrene (St) and the like.
3. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and the preparation method thereof according to claims 1 and 2, wherein the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises: the hydrophilic PHEAA amphiphilic polymer is one or a mixture of block copolymer, hyperbranched polymer and random copolymer, and in the step a), the mass of the hydrophilic PHEAA amphiphilic polymer additive is 2-40% of that of the polyvinylidene fluoride.
4. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and the preparation method thereof according to claim 1, wherein the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises the following components in parts by weight: in the step a), the additive is one or a mixture of polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, lithium chloride and the like.
5. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and the preparation method thereof according to claim 1, wherein the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises the following components in parts by weight: in the step a), the non-woven fabric is one or a mixture of more of polyester non-woven fabric, polypropylene non-woven fabric and polyamide non-woven fabric.
6. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and the preparation method thereof according to claim 1, wherein the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises the following components in parts by weight: in the step b), the water-soluble monomer is one or a mixture of more of piperazine, piperazine derivatives, m-phenylenediamine, phenylenediamine and polyethyleneimine. In the step b), the mass percent of the water-soluble monomer aqueous phase solution is 0.05-1.5%.
7. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and the preparation method thereof according to claim 1, wherein the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises: in the step b), the oil-soluble monomers are trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride. In the step b), the mass percent of the oil-soluble monomer organic phase solution is 0.05-0.2%.
8. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane and the preparation method thereof according to claim 1, wherein the polyvinylidene fluoride-based thin-layer composite nanofiltration membrane comprises: in the step b), the solvent of the organic phase solution is one or a mixture of ester solvents, hydrocarbon solvents or ether solvents.
9. The polyvinylidene fluoride-based thin-layer composite nanofiltration membrane prepared according to any one of claims 1 to 8.
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| CN116036896A (en) * | 2023-03-13 | 2023-05-02 | 天津工业大学 | Composite nanofiltration membrane with low molecular weight cutoff and narrow pore size distribution and preparation method thereof |
| CN117018890A (en) * | 2023-07-06 | 2023-11-10 | 贵州省材料产业技术研究院 | Polyvinylidene fluoride double-layer composite membrane based on interfacial polymerization and preparation method thereof |
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| KR20180113350A (en) * | 2017-04-06 | 2018-10-16 | 한국화학연구원 | Method for preparation of high flux polyamide composite membrane |
| CN109395594A (en) * | 2018-11-16 | 2019-03-01 | 天津工业大学 | A kind of preparation method of the amphiphilic polymer modified PVDF membrane based on poly- N- hydroxyethyl acrylamide |
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| KR20180113350A (en) * | 2017-04-06 | 2018-10-16 | 한국화학연구원 | Method for preparation of high flux polyamide composite membrane |
| CN108097071A (en) * | 2017-11-22 | 2018-06-01 | 北京新源国能科技集团股份有限公司 | A kind of preparation method of improved polyvinylidene fluoride NF membrane |
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| CN117018890A (en) * | 2023-07-06 | 2023-11-10 | 贵州省材料产业技术研究院 | Polyvinylidene fluoride double-layer composite membrane based on interfacial polymerization and preparation method thereof |
| CN117018890B (en) * | 2023-07-06 | 2024-05-14 | 贵州省材料产业技术研究院 | Polyvinylidene fluoride double-layer composite membrane based on interfacial polymerization and preparation method thereof |
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