CN114870658A - Preparation method of polyamide nanofiltration membrane with polyaldehyde crosslinked polyvinyl alcohol as intermediate layer - Google Patents
Preparation method of polyamide nanofiltration membrane with polyaldehyde crosslinked polyvinyl alcohol as intermediate layer Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 207
- 239000004372 Polyvinyl alcohol Substances 0.000 title claims abstract description 117
- 229920002451 polyvinyl alcohol Polymers 0.000 title claims abstract description 117
- 238000001728 nano-filtration Methods 0.000 title claims abstract description 84
- 239000004952 Polyamide Substances 0.000 title claims abstract description 62
- 229920002647 polyamide Polymers 0.000 title claims abstract description 62
- 229920001744 Polyaldehyde Polymers 0.000 title claims abstract description 30
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000004695 Polyether sulfone Substances 0.000 claims abstract description 60
- 229920006393 polyether sulfone Polymers 0.000 claims abstract description 60
- 238000001471 micro-filtration Methods 0.000 claims abstract description 53
- 239000000126 substance Substances 0.000 claims abstract description 44
- 238000000034 method Methods 0.000 claims abstract description 12
- 229920000768 polyamine Polymers 0.000 claims abstract description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 9
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims description 90
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 51
- 239000000243 solution Substances 0.000 claims description 47
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 46
- 239000000178 monomer Substances 0.000 claims description 40
- WSMYVTOQOOLQHP-UHFFFAOYSA-N Malondialdehyde Chemical compound O=CCC=O WSMYVTOQOOLQHP-UHFFFAOYSA-N 0.000 claims description 37
- 238000001035 drying Methods 0.000 claims description 34
- 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 30
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical group O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 claims description 27
- 239000011259 mixed solution Substances 0.000 claims description 27
- 229960000587 glutaral Drugs 0.000 claims description 25
- 238000002791 soaking Methods 0.000 claims description 22
- 229940118019 malondialdehyde Drugs 0.000 claims description 21
- 238000004132 cross linking Methods 0.000 claims description 20
- TUSDEZXZIZRFGC-UHFFFAOYSA-N 1-O-galloyl-3,6-(R)-HHDP-beta-D-glucose Natural products OC1C(O2)COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC1C(O)C2OC(=O)C1=CC(O)=C(O)C(O)=C1 TUSDEZXZIZRFGC-UHFFFAOYSA-N 0.000 claims description 19
- 239000001263 FEMA 3042 Substances 0.000 claims description 19
- LRBQNJMCXXYXIU-PPKXGCFTSA-N Penta-digallate-beta-D-glucose Natural products OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-PPKXGCFTSA-N 0.000 claims description 19
- LRBQNJMCXXYXIU-QWKBTXIPSA-N gallotannic acid Chemical compound OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@H]2[C@@H]([C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-QWKBTXIPSA-N 0.000 claims description 19
- 229940033123 tannic acid Drugs 0.000 claims description 19
- 235000015523 tannic acid Nutrition 0.000 claims description 19
- 229920002258 tannic acid Polymers 0.000 claims description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 238000002156 mixing Methods 0.000 claims description 12
- 235000013824 polyphenols Nutrition 0.000 claims description 10
- 239000003377 acid catalyst Substances 0.000 claims description 8
- LNTHITQWFMADLM-UHFFFAOYSA-N gallic acid Chemical compound OC(=O)C1=CC(O)=C(O)C(O)=C1 LNTHITQWFMADLM-UHFFFAOYSA-N 0.000 claims description 8
- 150000008442 polyphenolic compounds Chemical class 0.000 claims description 8
- PCSMJKASWLYICJ-UHFFFAOYSA-N Succinic aldehyde Chemical compound O=CCCC=O PCSMJKASWLYICJ-UHFFFAOYSA-N 0.000 claims description 7
- 229920005610 lignin Polymers 0.000 claims description 6
- VKOUCJUTMGHNOR-UHFFFAOYSA-N Diphenolic acid Chemical compound C=1C=C(O)C=CC=1C(CCC(O)=O)(C)C1=CC=C(O)C=C1 VKOUCJUTMGHNOR-UHFFFAOYSA-N 0.000 claims description 5
- LXEJRKJRKIFVNY-UHFFFAOYSA-N terephthaloyl chloride Chemical compound ClC(=O)C1=CC=C(C(Cl)=O)C=C1 LXEJRKJRKIFVNY-UHFFFAOYSA-N 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 229940074391 gallic acid Drugs 0.000 claims description 4
- 235000004515 gallic acid Nutrition 0.000 claims description 4
- LEQAOMBKQFMDFZ-UHFFFAOYSA-N glyoxal Chemical compound O=CC=O LEQAOMBKQFMDFZ-UHFFFAOYSA-N 0.000 claims description 4
- CTSLXHKWHWQRSH-UHFFFAOYSA-N oxalyl chloride Chemical compound ClC(=O)C(Cl)=O CTSLXHKWHWQRSH-UHFFFAOYSA-N 0.000 claims description 4
- -1 poly imino group Polymers 0.000 claims description 4
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 3
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 claims description 2
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 claims description 2
- SVYKKECYCPFKGB-UHFFFAOYSA-N N,N-dimethylcyclohexylamine Chemical compound CN(C)C1CCCCC1 SVYKKECYCPFKGB-UHFFFAOYSA-N 0.000 claims description 2
- LHIJANUOQQMGNT-UHFFFAOYSA-N aminoethylethanolamine Chemical compound NCCNCCO LHIJANUOQQMGNT-UHFFFAOYSA-N 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
- UKJLNMAFNRKWGR-UHFFFAOYSA-N cyclohexatrienamine Chemical group NC1=CC=C=C[CH]1 UKJLNMAFNRKWGR-UHFFFAOYSA-N 0.000 claims description 2
- 238000007598 dipping method Methods 0.000 claims description 2
- 229940015043 glyoxal Drugs 0.000 claims description 2
- 229940018564 m-phenylenediamine Drugs 0.000 claims description 2
- SXYFKXOFMCIXQW-UHFFFAOYSA-N propanedioyl dichloride Chemical compound ClC(=O)CC(Cl)=O SXYFKXOFMCIXQW-UHFFFAOYSA-N 0.000 claims description 2
- 125000003277 amino group Chemical group 0.000 claims 1
- 230000004907 flux Effects 0.000 abstract description 18
- 238000010612 desalination reaction Methods 0.000 abstract description 3
- 239000013535 sea water Substances 0.000 abstract description 2
- 238000004065 wastewater treatment Methods 0.000 abstract description 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 166
- 229940068984 polyvinyl alcohol Drugs 0.000 description 95
- 229940032330 sulfuric acid Drugs 0.000 description 22
- 238000000926 separation method Methods 0.000 description 16
- 238000010521 absorption reaction Methods 0.000 description 12
- 239000002131 composite material Substances 0.000 description 8
- 238000012360 testing method Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 230000014759 maintenance of location Effects 0.000 description 6
- 239000012527 feed solution Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 238000012695 Interfacial polymerization Methods 0.000 description 4
- 150000001263 acyl chlorides Chemical class 0.000 description 4
- 125000003172 aldehyde group Chemical group 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 230000002522 swelling effect Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000002346 layers by function Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- JPBGQGOQYGYTTA-UHFFFAOYSA-N 1,3,5-trimethylbenzene;hydrochloride Chemical compound Cl.CC1=CC(C)=CC(C)=C1 JPBGQGOQYGYTTA-UHFFFAOYSA-N 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000003431 cross linking reagent Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000005935 nucleophilic addition reaction Methods 0.000 description 2
- 239000012434 nucleophilic reagent Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- XKZQKPRCPNGNFR-UHFFFAOYSA-N 2-(3-hydroxyphenyl)phenol Chemical compound OC1=CC=CC(C=2C(=CC=CC=2)O)=C1 XKZQKPRCPNGNFR-UHFFFAOYSA-N 0.000 description 1
- 229920012266 Poly(ether sulfone) PES Polymers 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
- DHKHKXVYLBGOIT-UHFFFAOYSA-N acetaldehyde Diethyl Acetal Natural products CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 description 1
- 125000002777 acetyl group Chemical class [H]C([H])([H])C(*)=O 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 125000003158 alcohol group Chemical group 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000010889 donnan-equilibrium Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002373 hemiacetals Chemical group 0.000 description 1
- 229920001477 hydrophilic polymer Polymers 0.000 description 1
- 125000001841 imino group Chemical group [H]N=* 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
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- 238000013508 migration Methods 0.000 description 1
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- 230000035484 reaction time Effects 0.000 description 1
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- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
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Images
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
- B01D71/76—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74
- B01D71/82—Macromolecular material not specifically provided for in a single one of groups B01D71/08 - B01D71/74 characterised by the presence of specified groups, e.g. introduced by chemical after-treatment
-
- 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
-
- 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
- B01D69/12—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
- B01D71/38—Polyalkenylalcohols; Polyalkenylesters; Polyalkenylethers; Polyalkenylaldehydes; Polyalkenylketones; Polyalkenylacetals; Polyalkenylketals
-
- 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
-
- 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
Abstract
A preparation method of a polyamide nanofiltration membrane with polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer relates to a preparation method of a nanofiltration membrane, and aims to solve the technical problems that the membrane surface of the existing nanofiltration membrane with a sandwich structure is easy to pollute, the membrane is easy to expand and the stability is poor. The method comprises the following steps: firstly, preparing a polyaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane; secondly, the middle layer film absorbs polyamine or polyimine substances; III, multiple layers on the intermediate layer filmAnd (3) reacting the amino or polyimine substance with a polyacyl chloride substance to obtain the polyamide nanofiltration membrane taking the polyaldehyde crosslinked polyvinyl alcohol as the middle layer. The rejection rate of the nanofiltration membrane is 90-98%, and the membrane flux is 8.0-25L (m) 2 ·bar·h) ‑1 . Can be applied to the fields of wastewater treatment and seawater desalination.
Description
Technical Field
The invention relates to a preparation method of a nanofiltration membrane.
Background
The nanofiltration membrane separation technology in the membrane separation technology is a common strategy and means in seawater desalination, however, the Traded-off effect of the nanofiltration membrane is a main reason which troubles the popularization of the nanofiltration membrane technology, namely, the rejection rate and the membrane flux of the nanofiltration membrane have opposite increasing trends in numerical values. In the prior art, hydrophilic substances are embedded between a base membrane and a selective separation layer to improve the comprehensive separation performance of the nanofiltration membrane, and the nanofiltration membrane with a sandwich structure is called TFN for short. A nanofiltration Membrane with a sandwich structure is prepared by a layer-by-layer self-assembly method through a Polyphenol engineered membranes with a double charged sandwich structure for low-pressure molecular separation (Polyphenol engineered membranes with a reduced charge sandwich structure for low-pressure molecular separation) on 601 year 2020 of Journal of Membrane Science (Journal of Membrane Science). However, the separation functional layer of the nanofiltration membrane is easy to fall off and generate swelling effect, and polymer ions are easy to damage, so that the membrane surface of the nanofiltration membrane is easy to be polluted, and the membrane is easy to expand and has poor stability.
Disclosure of Invention
The invention provides a preparation method of a polyamide nanofiltration membrane with polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer, aiming at solving the technical problems that the membrane surface of the existing nanofiltration membrane with a sandwich structure is easy to pollute, the membrane is easy to expand and the stability is poor.
The preparation method of the polyamide nanofiltration membrane with polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a multi-aldehyde cross-linked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding the aldehydic substance, the polyvinyl alcohol, the strong acid catalyst and the polyhydroxy substance into water according to the mass percentage concentration of the aldehydic substance of 0.01-50%, the mass percentage concentration of the polyvinyl alcohol of 0.01-50%, the mass percentage concentration of the strong acid catalyst of 0.01-50% and the mass percentage concentration of the polyhydroxy substance of 0.01-50%, and uniformly mixing to obtain a mixed solution; dipping the polyether sulfone microfiltration membrane in the mixed solution for 1-200 min, taking out the polyether sulfone microfiltration membrane, and placing the polyether sulfone microfiltration membrane in a drying oven at the temperature of 10-200 ℃ for crosslinking for 1-200 min to obtain an intermediate layer membrane;
secondly, soaking the intermediate layer film in a polyamine or polyimine substance solution with the mass percentage concentration of 0.01-50% for 1-200 min, then taking out the intermediate layer film, and drying at room temperature for 1-200 min to obtain the intermediate layer film absorbing polyamine or polyimine substance monomers;
thirdly, preparing n-hexane solution of the polyacyl chloride-based substance according to the mass percentage concentration of the polyacyl chloride-based substance of 0.001% -50%, then placing the middle layer film absorbing the polyamine or polyimine-based substance monomer in the n-hexane solution of the polyacyl chloride-based substance for 1-500 s, taking out the middle layer film, and then placing the middle layer film in a drying oven at the temperature of 10-200 ℃ for 1-200 min to obtain the polyamide nanofiltration membrane taking the polyaldehyde crosslinked polyvinyl alcohol as the middle layer.
Further, the multi-aldehyde substance in the first step is glutaraldehyde, glyoxal, malonaldehyde or succinaldehyde.
Further, the strong acid catalyst in the first step is sulfuric acid or hydrochloric acid.
Further, the polyhydroxy substance in the first step is tannic acid, lignin polyphenol, gallic acid, tannic acid or hexahydroxy diphenol acid. The polyhydroxy substance can improve the hydrophilicity of the aqueous solution, reduce the monomer migration rate of the interfacial polymerization reaction of the aqueous phase monomer solution and improve the interfacial polymerization efficiency.
Furthermore, in the mixed solution in the first step, the mass percentage concentration of the aldehyde-containing substance is 0.1-1%, the mass percentage concentration of the polyvinyl alcohol is 1-3%, the mass percentage concentration of the strong acid catalyst is 0.1-1%, and the mass percentage concentration of the polyhydroxy substance is 0.1-3%.
Further, in the second step, the polyamine or polyimine group material is piperazine, hydroxyethyl ethylenediamine, m-phenylenediamine, 1, 4-cyclic ethylenediamine, p-phenylenediamine, 3, 5-diamino-N- (4-aminophenyl) or 1, 3-cyclohexyldimethylamine.
Further, the poly (acyl chloride) -based substance mentioned in the third step is trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, oxalyl chloride or malonyl chloride.
Furthermore, the mass percentage concentration of the polyamine group or the polyimine group substance solution in the step two is 0.1 to 3 percent;
furthermore, the mass percentage concentration of the poly-acyl chloride substances in the normal hexane solution of the poly-acyl chloride substances in the third step is 0.1-1%.
According to the invention, hydrophilic polyvinyl alcohol is more tightly embedded into the surface of the base membrane in a crosslinking mode, and the hydrophilic polyvinyl alcohol intermediate layer with a crosslinking structure can more effectively absorb and store monomers, so that reaction monomers are more uniformly dispersed on the surface of the intermediate layer, and generation of a more uniform outermost layer is promoted. After the polyvinyl alcohol is crosslinked, the swelling effect of the polyvinyl alcohol is reduced, so that the performance of the nanofiltration membrane product is more stable, and meanwhile, the pollution probability of the nanofiltration membrane product is greatly reduced because the polyvinyl alcohol is the middle layer.
The rejection rate of the polyamide nanofiltration membrane prepared by the invention is 90% -98%, and the membrane flux is 8.0-25L (m) 2 ·bar·h) -1 . Can be applied to wastewater treatment and seawaterThe field of desalination.
Drawings
FIG. 1 is a Fourier transform infrared spectrum of the polyethersulfone microfiltration membrane, the intermediate layer membrane prepared in the first step, and the polyamide nanofiltration membrane using glutaraldehyde crosslinked polyvinyl alcohol prepared in the third step as the intermediate layer in example 1;
fig. 2 is a fourier transform infrared spectrum of the polyethersulfone microfiltration membrane, the intermediate layer membrane prepared in the first step, and the polyamide nanofiltration membrane using glutaraldehyde crosslinked polyvinyl alcohol prepared in the third step as the intermediate layer in example 1.
Detailed Description
The following examples are used to demonstrate the beneficial effects of the present invention.
Example 1: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a glutaraldehyde cross-linked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding glutaraldehyde, polyvinyl alcohol, sulfuric acid and tannic acid into water according to the mass percentage concentration of 0.50% of glutaraldehyde, 0.6% of polyvinyl alcohol, 0.10% of sulfuric acid and 0.2% of tannic acid, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 5min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 70 ℃ for crosslinking treatment for 20min to obtain an intermediate layer membrane; in the step, dilute sulfuric acid is used as a catalyst on a polyether sulfone microfiltration membrane, and a glutaraldehyde crosslinking agent and hydrophilic polymer polyvinyl alcohol are subjected to crosslinking reaction;
secondly, soaking the intermediate layer film in 0.45 mass percent piperazine solution for 2min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 20min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.2%, then placing the intermediate layer membrane absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for keeping for 25s, taking out the intermediate layer membrane, and then placing the intermediate layer membrane in a drying oven at the temperature of 70 ℃ for keeping for 20min to obtain the polyamide nanofiltration membrane taking the glutaraldehyde crosslinking polyvinyl alcohol as the intermediate layer; in the step, piperazine and mesitylene chloride are subjected to interfacial polymerization reaction at an interface of two phases to obtain a polyamide selective separation layer, and then heating treatment is carried out to improve the reaction strength of polyamide and increase the stability of a polyamide structure.
The fourier transform infrared spectrogram of the polyamide nanofiltration membrane with glutaraldehyde crosslinked polyvinyl alcohol as the intermediate layer prepared in the example is shown in fig. 1 and fig. 2. In the figure, PES basal membrane represents a polyether sulfone microfiltration membrane, PES-PVA represents an intermediate layer membrane prepared in the first step, and PES-PVA-PA represents a polyamide nanofiltration membrane with glutaraldehyde cross-linked polyvinyl alcohol prepared in the third step as an intermediate layer; from the Fourier transform infrared spectrogram, the change of the surface chemical structure of three kinds of film materials can be obtained. 1577cm can be found in the infrared spectrogram curve chart of PES-PVA-PA composite membrane -1 The in-plane stretching vibration absorption peak of-N-H appears and is at 1410cm -1 Has a C-N telescopic vibration absorption peak of 1577cm -1 And 1410cm -1 The two absorption peaks are characteristic absorption peaks of polyamide, so that a stable polyamide surface structure can be formed on the surface of the PES-PVA-PA composite film. 3282cm can be found in the IR plot of a PES-PVA interlayer film -1 the-OH absorption peak of the polyvinyl alcohol molecule appears, the peak value is strong, the peak position is wide, the absorption is mainly caused by the superposition of residual hydroxyl intramolecular association absorption and intermolecular hydroxyl association absorption in the polyvinyl alcohol structure, and the polyvinyl alcohol is caused by crosslinking with glutaraldehyde, so that the fact that PVA is attached to the surface of the PES basal membrane to form an intermediate membrane under the action of a glutaraldehyde crosslinking agent can also be proved.
As can be seen from FIG. 2, the common feature among the PES base film, the PES-PVA intermediate layer film and the PES-PVA-PA composite film is that many identical peaks appear. 1320cm of infrared spectrum of the three -1 And 1237cm -1 The absorption peak of C-O-C stretching vibration appears at 1147cm -1 And 1103cm -1 The absorption peak of S ═ O stretching vibration appears at the position, and the characteristic absorption peak of PES basal membrane is formed at both peaks, therebyIt can be found that after the surface of the PES base film is modified, a thin intermediate layer is formed on the surface of the PES base film, and a thin selective polyamide separation layer is also formed on the surface of the PES-PVA intermediate layer film, so that the characteristic absorption peak of the PES base film appears on the surfaces of the three film materials.
The polyamide nanofiltration membrane with the glutaraldehyde crosslinked polyvinyl alcohol as the middle layer prepared in the embodiment is of a three-layer membrane structure, the bottom layer is polyether sulfone (PES) for providing a mechanical effect, the middle layer plays a role in improving the membrane performance, and the upper layer is a functional layer for membrane separation.
Principle of formation of intermediate layer: the aldehyde group in the glutaraldehyde structure is a strong polar group, and carbon in the aldehyde group has strong electropositivity, so that the aldehyde group is easily attacked by hydroxyl in a nucleophilic reagent polyvinyl alcohol (PVA) under an acidic condition to generate nucleophilic addition reaction, so that the carbon in the aldehyde group of the glutaraldehyde is changed into carbon positive ions, and the polymer structure with oxonium ions is formed because the electronegativity of oxygen is greater than that of carbon, so that the structure is extremely unstable, and a stable hemiacetal structure is generated. The hemiacetal hydroxyl group is easy to protonate in an acid solution to generate a better leaving group, which is beneficial to the removal of water, thereby generating a stable acetal product.
The upper layer is a selective separation layer, and the formation principle is as follows: firstly, piperazine is used as a nucleophilic reagent to carry out nucleophilic addition on mesitylene chloride to form an amide cation intermediate, and then the amide cation intermediate is deionized to obtain an amide product. Because piperazine has two imino groups and trimesoyl chloride contains three acyl chloride groups, a compact polyamide network structure is easily formed.
Polyvinyl alcohol (PVA) is a hydrophilic substance with a polyhydroxy structure, the polyhydroxy structure endows PVA with good modification conditions, Glutaraldehyde (GA) crosslinking PVA can reduce the possibility of forming a compact packing structure in the PVA film forming process, and the probability of generating a network intermediate layer is greatly increased, so that the structural performance of the formed intermediate layer is more excellent, and a foundation is laid for the generation of a polyamide functional layer; the crosslinking effect can also reduce the number of hydroxyl groups, reduce the swelling effect of the PVA intermediate layer and strengthen the membrane performance of the composite nanofiltration membrane. Tannic Acid (TA) contains abundant phenolic hydroxyl active groups, and has the characteristics of high density of surface functional groups, good chemical stability and hydrophilicity and the like. More importantly, the TA serving as the composite nanofiltration membrane additive has a loose molecular structure and a large molecular weight, and can mix the viscosity of a solution, so that the diffusion rate of a reaction monomer in the mixed solution is reduced, the interfacial polymerization reaction time is shortened, a compact selective separation layer is formed, the thickness of the selective separation layer is greatly reduced, a unique nano-wrinkled structure is successfully formed on the surface of the composite membrane, and the comprehensive separation performance of the composite nanofiltration membrane is improved. In addition, the strong polarity of phenolic hydroxyl of the Tannic Acid (TA) can strengthen the electronegativity of the polyamide composite nanofiltration membrane, so that the selective separation layer can be provided with more negative charges, the Donnan effect can be strengthened, the electrostatic repulsion effect on anions is also strengthened, and the separation performance of the nanofiltration membrane is indirectly strengthened.
The glutaraldehyde crosslinked polyvinyl alcohol prepared in this example 1 was used as a polyamide nanofiltration membrane for the intermediate layer to perform membrane flux and rejection tests.
The membrane flux was tested as follows: and (3) installing the prepared nanofiltration membrane in a test groove, and then starting an instrument to regulate the water inlet pressure and flow. In addition, before the test, the nanofiltration membrane performance tester needs to be started in advance to operate under the condition of 7bar, and the nanofiltration membrane performance evaluation can not be carried out until the water inlet pressure and the water flow are stable. The fixed test pressure is unchanged in the test process, and the water volume in the membrane filtrate collecting device is measured for a certain time, so that the membrane flux of the nanofiltration membrane can be obtained. The formula for calculating the membrane flux is as follows:
in the formula, L P Is the membrane flux, in units of L (m) 2 ·bar·h) -1 (ii) a V is the volume of water produced in t time, and the unit is L; a is the effective area of the membrane module, and the unit is m 2 (ii) a t is the sampling time in h.
The retention test method is as follows: at a concentration of 1000 mg.L -1 Sodium sulfate solution ofThe test pressure is 3bar as the test solution of the rejection rate, and in addition, the nanofiltration membrane performance tester needs to be started in advance before the test to operate under the condition of 3bar, and the nanofiltration membrane performance evaluation can not be carried out until the pressure of the feed solution is stable. And then, calculating the concentration of the discharged solution according to the relation between the conductivity of the feeding solution and the conductivity of the discharged solution, thereby calculating the rejection rate of the nano-filtration membrane. The retention rate is calculated as follows:
in the formula, R is the retention rate; c P As the concentration of the feed solution, the unit is mS (cm) -1 ；C R Is the concentration of the feed solution, in units of mS (cm) -1 ；C P Conductivity mS (cm) for the feed solution -1 In units of; c P Is the conductivity of the feed solution, in mS (cm) -1 。
The retention rate of the polyamide nanofiltration membrane taking glutaraldehyde crosslinked polyvinyl alcohol as the middle layer prepared in the embodiment is 95.05%, and the membrane flux is 10.76L (m) 2 ·bar·h) -1 。
The glutaraldehyde crosslinked polyvinyl alcohol prepared by the embodiment is used as the polyamide nanofiltration membrane of the middle layer, and the polyvinyl alcohol is not easily polluted because of being positioned in the middle layer, and is in a crosslinked state, so that the swelling effect of the glutaraldehyde crosslinked polyvinyl alcohol is reduced, and the stability of the nanofiltration membrane is improved.
Example 2: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a glutaraldehyde cross-linked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding glutaraldehyde, polyvinyl alcohol, sulfuric acid and tannic acid into water according to the mass percentage concentration of 0.50% of glutaraldehyde, 1.0% of polyvinyl alcohol, 0.10% of sulfuric acid and 1.5% of tannic acid, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 5min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 65 ℃ for crosslinking treatment for 20min to obtain an intermediate layer membrane;
secondly, soaking the intermediate layer film in 0.7 mass percent piperazine solution for 2min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 20min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.1%, then placing the intermediate layer membrane absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for keeping for 25s, taking out the intermediate layer membrane, and then placing the intermediate layer membrane in a drying oven at the temperature of 70 ℃ for keeping for 20min to obtain the polyamide nanofiltration membrane taking the glutaraldehyde crosslinking polyvinyl alcohol as the intermediate layer;
the retention rate of the polyamide nanofiltration membrane using the glutaraldehyde crosslinked polyvinyl alcohol prepared in the embodiment as the middle layer is 95.38%, and the membrane flux is 11.26L (m) 2 ·bar·h) -1 。
Example 3: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a succinaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding succinaldehyde, polyvinyl alcohol, sulfuric acid and tannic acid into water according to the mass percentage concentration of 0.40 percent of succinaldehyde, 2.0 percent of polyvinyl alcohol, 0.20 percent of sulfuric acid and 1.5 percent of tannic acid, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 10min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 50 ℃ for crosslinking treatment for 15min to obtain an intermediate layer membrane;
secondly, soaking the intermediate layer film in 0.5% by mass of piperazine solution for 5min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 10min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.2%, then placing the intermediate layer membrane absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for 30s, taking out the intermediate layer membrane, and then placing the intermediate layer membrane in a drying oven at the temperature of 50 ℃ for 30min to obtain the polyamide nanofiltration membrane taking the succinaldehyde crosslinked polyvinyl alcohol as the intermediate layer;
the retention rate of the polyamide nanofiltration membrane with the succinaldehyde crosslinked polyvinyl alcohol prepared in the embodiment as the middle layer is 95.12%, and the membrane flux is 11.29L (m) 2 ·bar·h) -1 。
Example 4: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a malonaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding malondialdehyde, polyvinyl alcohol, sulfuric acid and tannic acid into water according to the mass percentage concentration of 0.20% of malondialdehyde, 3.0% of polyvinyl alcohol, 0.50% of sulfuric acid and 2.5% of tannic acid, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 15min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 60 ℃ for crosslinking treatment for 10min to obtain an intermediate layer membrane;
soaking the intermediate layer film in 0.6 mass percent piperazine solution for 8min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 15min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.3 percent, then placing the intermediate layer film absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for keeping for 40s, taking out the intermediate layer film, and then placing the intermediate layer film in a drying oven at the temperature of 60 ℃ for keeping for 20min to obtain the polyamide nanofiltration membrane taking the malonaldehyde crosslinked polyvinyl alcohol as the intermediate layer;
the rejection rate of the polyamide nanofiltration membrane using the malondialdehyde crosslinked polyvinyl alcohol as the middle layer prepared in the embodiment is 94.23%, and the membrane flux is 10.56L (m) 2 ·bar·h) -1 。
Example 5: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a malonaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding malondialdehyde, polyvinyl alcohol, sulfuric acid and lignin polyphenol into water according to the mass percentage concentration of malondialdehyde of 0.50%, the mass percentage concentration of polyvinyl alcohol of 1.0%, the mass percentage concentration of sulfuric acid of 0.80% and the mass percentage concentration of lignin polyphenol of 0.5%, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 10min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 50 ℃ for crosslinking treatment for 15min to obtain an intermediate layer membrane;
soaking the intermediate layer film in 0.5 mass percent piperazine solution for 20min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 30min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.5%, then placing the intermediate layer film absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for keeping for 50s, taking out the intermediate layer film, and then placing the intermediate layer film in a drying oven at the temperature of 50 ℃ for keeping for 10min to obtain the polyamide nanofiltration membrane taking the malonaldehyde crosslinked polyvinyl alcohol as the intermediate layer;
the rejection rate of the polyamide nanofiltration membrane using the malondialdehyde crosslinked polyvinyl alcohol prepared in the embodiment as the middle layer is 95.19%, and the membrane flux is 11.76L (m) 2 ·bar·h) -1 。
Example 6: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a malonaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding malondialdehyde, polyvinyl alcohol, sulfuric acid and lignin polyphenol into water according to the mass percentage concentration of malondialdehyde of 0.50%, the mass percentage concentration of polyvinyl alcohol of 1.0%, the mass percentage concentration of sulfuric acid of 0.80% and the mass percentage concentration of lignin polyphenol of 0.8%, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 10min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 50 ℃ for crosslinking treatment for 15min to obtain an intermediate layer membrane;
soaking the intermediate layer film in 0.5 mass percent piperazine solution for 20min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 30min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.5%, then placing the intermediate layer film absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for keeping for 50s, taking out the intermediate layer film, and then placing the intermediate layer film in a drying oven at the temperature of 50 ℃ for keeping for 10min to obtain the polyamide nanofiltration membrane taking the malonaldehyde crosslinked polyvinyl alcohol as the intermediate layer;
the rejection rate of the polyamide nanofiltration membrane using the malondialdehyde crosslinked polyvinyl alcohol as the middle layer prepared in the embodiment is 92.47%, and the membrane flux is 11.81L (m) 2 ·bar·h) -1 。
Example 7: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a malonaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding malonaldehyde, polyvinyl alcohol, sulfuric acid and gallic acid into water according to the mass percentage concentration of malonaldehyde of 0.70%, polyvinyl alcohol of 2.0%, sulfuric acid of 0.90% and gallic acid of 0.6%, and mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 15min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 60 ℃ for crosslinking treatment for 20min to obtain an intermediate layer membrane;
secondly, soaking the intermediate layer film in 0.6 mass percent piperazine solution for 30min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 15min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.8%, then placing the intermediate layer film absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for 35s, taking out the intermediate layer film, and then placing the intermediate layer film in a baking oven at the temperature of 60 ℃ for 10min to obtain the polyamide nanofiltration membrane taking the malonaldehyde crosslinked polyvinyl alcohol as the intermediate layer;
the rejection rate of the polyamide nanofiltration membrane using the malondialdehyde crosslinked polyvinyl alcohol prepared in the embodiment as the middle layer is 94.86%, and the membrane flux is 9.67L (m) 2 ·bar·h) -1 。
Example 8: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a malonaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding malondialdehyde, polyvinyl alcohol, sulfuric acid and tannic acid into water according to the mass percentage concentration of 0.80% of malondialdehyde, 1.0% of polyvinyl alcohol, 0.60% of sulfuric acid and 0.9% of tannic acid, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 16min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 50 ℃ for crosslinking treatment for 10min to obtain an intermediate layer membrane;
soaking the intermediate layer film in 0.5 mass percent piperazine solution for 20min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 16min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.7%, then placing the intermediate layer film absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for keeping for 25s, taking out the intermediate layer film, and then placing the intermediate layer film in a drying oven at the temperature of 50 ℃ for keeping for 20min to obtain the polyamide nanofiltration membrane taking the malonaldehyde crosslinked polyvinyl alcohol as the intermediate layer;
the rejection rate of the polyamide nanofiltration membrane using the malondialdehyde crosslinked polyvinyl alcohol as the middle layer prepared in the embodiment is 96.26%, and the membrane flux is 8.96L (m) 2 ·bar·h) -1 。
Example 9: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a malonaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding malondialdehyde, polyvinyl alcohol, sulfuric acid and hexahydroxy diphenolic acid into water according to the mass percentage concentration of malondialdehyde of 0.50%, the mass percentage concentration of polyvinyl alcohol of 3.0%, the mass percentage concentration of sulfuric acid of 0.30% and the mass percentage concentration of hexahydroxy diphenolic acid of 0.50%, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 30min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 20 ℃ for crosslinking treatment for 40min to obtain an intermediate layer membrane;
soaking the intermediate layer film in 0.5 mass percent piperazine solution for 10min to absorb piperazine monomers, taking out the intermediate layer film, and drying at room temperature for 10min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing a n-hexane solution of the trimesoyl chloride according to the mass percentage concentration of the trimesoyl chloride of 0.6%, then placing the intermediate layer film absorbing the piperazine monomer in the n-hexane solution of the trimesoyl chloride for keeping for 60s, taking out the intermediate layer film, and then placing the intermediate layer film in a drying oven at the temperature of 80 ℃ for keeping for 10min to obtain the polyamide nanofiltration membrane taking the malonaldehyde crosslinked polyvinyl alcohol as the intermediate layer;
the rejection rate of the polyamide nanofiltration membrane using the malondialdehyde crosslinked polyvinyl alcohol prepared in the embodiment as the middle layer is 92.65%, and the membrane flux is 9.25L (m) 2 ·bar·h) -1 。
Example 10: the preparation method of the polyamide nanofiltration membrane with the polyaldehyde crosslinked polyvinyl alcohol as the middle layer comprises the following steps:
firstly, preparing a malonaldehyde crosslinked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding malondialdehyde, polyvinyl alcohol, sulfuric acid and hexahydroxy diphenolic acid into water according to the mass percentage concentration of malondialdehyde of 0.10%, the mass percentage concentration of polyvinyl alcohol of 2.0%, the mass percentage concentration of sulfuric acid of 0.10% and the mass percentage concentration of hexahydroxy diphenolic acid of 0.20%, and uniformly mixing to obtain a mixed solution; soaking the polyethersulfone microfiltration membrane in the mixed solution for 16min, taking out the polyethersulfone microfiltration membrane, and placing the polyethersulfone microfiltration membrane in a drying oven at the temperature of 30 ℃ for crosslinking treatment for 30min to obtain an intermediate layer membrane;
secondly, soaking the intermediate layer film in 0.3 mass percent piperazine solution for 30min to absorb piperazine monomers, taking out the intermediate layer film, and drying and keeping the intermediate layer film at room temperature for 30min to obtain the intermediate layer film absorbing the piperazine monomers;
thirdly, preparing n-hexane solution of the terephthaloyl chloride according to the mass percentage concentration of the terephthaloyl chloride of 0.5%, then placing the intermediate layer membrane absorbing the piperazine monomer in the n-hexane solution of the terephthaloyl chloride for keeping for 35s, taking out the intermediate layer membrane, and then placing the intermediate layer membrane in a baking oven at the temperature of 70 ℃ for keeping for 40min to obtain the polyamide nanofiltration membrane taking the malondialdehyde crosslinked polyvinyl alcohol as the intermediate layer;
the rejection rate of the polyamide nanofiltration membrane using the malondialdehyde crosslinked polyvinyl alcohol as the middle layer prepared in the embodiment is 91.34%, and the membrane flux is 12.45L (m) 2 ·bar·h) -1 。
Claims (9)
1. A preparation method of a polyamide nanofiltration membrane with polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer is characterized by comprising the following steps:
firstly, preparing a multi-aldehyde cross-linked polyvinyl alcohol intermediate layer film on the surface of a polyether sulfone microfiltration membrane: adding the aldehydic substance, the polyvinyl alcohol, the strong acid catalyst and the polyhydroxy substance into water according to the mass percentage concentration of the aldehydic substance of 0.01-50%, the mass percentage concentration of the polyvinyl alcohol of 0.01-50%, the mass percentage concentration of the strong acid catalyst of 0.01-50% and the mass percentage concentration of the polyhydroxy substance of 0.01-50%, and uniformly mixing to obtain a mixed solution; dipping the polyether sulfone microfiltration membrane in the mixed solution for 1-200 min, taking out the polyether sulfone microfiltration membrane, and placing the polyether sulfone microfiltration membrane in a drying oven at the temperature of 10-200 ℃ for crosslinking for 1-200 min to obtain an intermediate layer membrane;
secondly, soaking the intermediate layer film in a polyamine or polyimine substance solution with the mass percentage concentration of 0.01-50% for 1-200 min, then taking out the intermediate layer film, and drying at room temperature for 1-200 min to obtain the intermediate layer film of the intermediate layer film monomer absorbing the polyamine or polyimine substance monomer;
thirdly, preparing n-hexane solution of the polyacyl chloride-based substance according to the mass percentage concentration of the polyacyl chloride-based substance of 0.001% -50%, then placing the middle layer film absorbing the polyamine or polyimine-based substance monomer in the n-hexane solution of the polyacyl chloride-based substance for 1-500 s, taking out the middle layer film, and then placing the middle layer film in a drying oven at the temperature of 10-200 ℃ for 1-200 min to obtain the polyamide nanofiltration membrane taking the polyaldehyde crosslinked polyvinyl alcohol as the middle layer.
2. The method for preparing the nanofiltration membrane using the polyaldehyde crosslinked polyvinyl alcohol as the intermediate layer according to claim 1, wherein the polyaldehyde group substance in the step one is glutaraldehyde, glyoxal, malondialdehyde, or succindialdehyde.
3. The method for preparing a polyamide nanofiltration membrane using polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer according to claim 1 or 2, wherein the strong acid catalyst in the first step is sulfuric acid or hydrochloric acid.
4. The method for preparing a polyamide nanofiltration membrane using polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer according to claim 1 or 2, wherein the polyhydroxy substance in the first step is tannic acid, lignin polyphenol, gallic acid, tannic acid or hexahydroxy diphenolic acid.
5. The method for preparing a nanofiltration membrane using polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer according to claim 1 or 2, wherein the polyamine or polyimine group in the second step is piperazine, hydroxyethylethylenediamine, ethylenediamine, m-phenylenediamine, 1, 4-cyclic ethylenediamine, p-phenylenediamine, 3, 5-diamino-N- (4-aminophenyl) or 1, 3-cyclohexyldimethylamine.
6. The method for preparing a polyamide nanofiltration membrane using polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer according to claim 1 or 2, wherein the polychloride-based substance in the third step is trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, oxalyl chloride or malonyl chloride.
7. The method for preparing a polyamide nanofiltration membrane using polyaldehyde crosslinked polyvinyl alcohol as an intermediate layer according to claim 1 or 2, wherein in the mixed solution in the first step, the mass percent concentration of the polyaldehyde group substance is 0.1-1%, the mass percent concentration of the polyvinyl alcohol is 1-3%, the mass percent concentration of the strong acid catalyst is 0.1-1%, and the mass percent concentration of the polyhydroxy substance is 0.1-3%.
8. The method for preparing the polyamide nanofiltration membrane using the polyaldehyde crosslinked polyvinyl alcohol as the middle layer according to claim 1 or 2, wherein the mass percentage concentration of the solution of the poly amino group or the poly imino group substances in the second step is 0.1-3%.
9. The method for preparing the polyamide nanofiltration membrane using the polyaldehyde crosslinked polyvinyl alcohol as the middle layer according to claim 1 or 2, wherein the mass percentage concentration of the polyacyl chloride-based substance in the n-hexane solution of the polyacyl chloride-based substance in the step three is 0.1-1%.
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| WO2024044869A1 (en) * | 2022-08-29 | 2024-03-07 | 深圳市星源材质科技股份有限公司 | Modified nanofiltration support membrane, preparation method therefor, and composite nanofiltration membrane |
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| CN116808842A (en) * | 2023-08-30 | 2023-09-29 | 国家电投集团氢能科技发展有限公司 | Modified microporous membrane, composite ion exchange membrane, and preparation methods and applications thereof |
| CN116808842B (en) * | 2023-08-30 | 2023-10-27 | 国家电投集团氢能科技发展有限公司 | Modified microporous membrane, composite ion exchange membrane, and preparation methods and applications thereof |
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