CN115475538A - Hollow fiber composite nanofiltration membrane based on COFs intermediate layer and preparation method thereof - Google Patents
Hollow fiber composite nanofiltration membrane based on COFs intermediate layer and preparation method thereof Download PDFInfo
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- CN115475538A CN115475538A CN202110664258.1A CN202110664258A CN115475538A CN 115475538 A CN115475538 A CN 115475538A CN 202110664258 A CN202110664258 A CN 202110664258A CN 115475538 A CN115475538 A CN 115475538A
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- hollow fiber
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- 239000012528 membrane Substances 0.000 title claims abstract description 133
- 239000012510 hollow fiber Substances 0.000 title claims abstract description 90
- 239000013310 covalent-organic framework Substances 0.000 title claims abstract description 83
- 238000001728 nano-filtration Methods 0.000 title claims abstract description 65
- 239000002131 composite material Substances 0.000 title claims abstract description 59
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 48
- 238000000926 separation method Methods 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000012695 Interfacial polymerization Methods 0.000 claims abstract description 18
- 238000011065 in-situ storage Methods 0.000 claims abstract description 8
- 239000000126 substance Substances 0.000 claims abstract 2
- 239000000178 monomer Substances 0.000 claims description 56
- 210000004379 membrane Anatomy 0.000 claims description 54
- 239000010410 layer Substances 0.000 claims description 49
- 239000000243 solution Substances 0.000 claims description 45
- 239000007864 aqueous solution Substances 0.000 claims description 37
- 239000012074 organic phase Substances 0.000 claims description 29
- 230000035699 permeability Effects 0.000 claims description 29
- 239000002086 nanomaterial Substances 0.000 claims description 26
- 230000014759 maintenance of location Effects 0.000 claims description 21
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 18
- GLUUGHFHXGJENI-UHFFFAOYSA-N diethylenediamine Natural products C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims description 18
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 18
- 239000008346 aqueous phase Substances 0.000 claims description 16
- 150000003839 salts Chemical class 0.000 claims description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 13
- 229920000768 polyamine Polymers 0.000 claims description 13
- 229910001385 heavy metal Inorganic materials 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 10
- 239000003960 organic solvent Substances 0.000 claims description 10
- 238000002791 soaking Methods 0.000 claims description 10
- 239000011780 sodium chloride Substances 0.000 claims description 9
- 239000012071 phase Substances 0.000 claims description 8
- 239000004952 Polyamide Substances 0.000 claims description 6
- 229920002647 polyamide Polymers 0.000 claims description 6
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 claims description 5
- 239000000654 additive Substances 0.000 claims description 5
- 229920002492 poly(sulfone) Polymers 0.000 claims description 5
- 238000000108 ultra-filtration Methods 0.000 claims description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 4
- 230000000996 additive effect Effects 0.000 claims description 4
- 210000002469 basement membrane Anatomy 0.000 claims description 3
- UWCPYKQBIPYOLX-UHFFFAOYSA-N benzene-1,3,5-tricarbonyl chloride Chemical group ClC(=O)C1=CC(C(Cl)=O)=CC(C(Cl)=O)=C1 UWCPYKQBIPYOLX-UHFFFAOYSA-N 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 239000011229 interlayer Substances 0.000 claims description 3
- 229920003169 water-soluble polymer Polymers 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
- 239000004135 Bone phosphate Substances 0.000 claims description 2
- 239000004695 Polyether sulfone Substances 0.000 claims description 2
- 150000004985 diamines Chemical group 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 150000002500 ions Chemical class 0.000 claims description 2
- 229940018564 m-phenylenediamine Drugs 0.000 claims description 2
- 238000001471 micro-filtration Methods 0.000 claims description 2
- 125000004193 piperazinyl group Chemical group 0.000 claims description 2
- 229920006393 polyether sulfone Polymers 0.000 claims description 2
- 239000012266 salt solution Substances 0.000 claims description 2
- NGNBDVOYPDDBFK-UHFFFAOYSA-N 2-[2,4-di(pentan-2-yl)phenoxy]acetyl chloride Chemical compound CCCC(C)C1=CC=C(OCC(Cl)=O)C(C(C)CCC)=C1 NGNBDVOYPDDBFK-UHFFFAOYSA-N 0.000 claims 3
- XJUSNFMGLDTILB-UHFFFAOYSA-N OC(CC(C1)(C(C2=CC=CC=C2)=O)O)(CC1(C(C1=CC=CC=C1)=O)O)C(C1=CC=CC=C1)=O Chemical compound OC(CC(C1)(C(C2=CC=CC=C2)=O)O)(CC1(C(C1=CC=CC=C1)=O)O)C(C1=CC=CC=C1)=O XJUSNFMGLDTILB-UHFFFAOYSA-N 0.000 claims 1
- 238000010276 construction Methods 0.000 claims 1
- 239000011521 glass Substances 0.000 claims 1
- 230000004907 flux Effects 0.000 abstract description 8
- 230000008569 process Effects 0.000 abstract description 6
- 239000011148 porous material Substances 0.000 abstract description 4
- 230000001105 regulatory effect Effects 0.000 abstract description 4
- 239000000463 material Substances 0.000 abstract description 3
- 238000009826 distribution Methods 0.000 abstract description 2
- 239000002585 base Substances 0.000 description 27
- 239000011734 sodium Substances 0.000 description 11
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 238000011056 performance test Methods 0.000 description 7
- 150000001408 amides Chemical class 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 3
- 150000001263 acyl chlorides Chemical class 0.000 description 3
- 229910017053 inorganic salt Inorganic materials 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 235000000177 Indigofera tinctoria Nutrition 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- NKLPQNGYXWVELD-UHFFFAOYSA-M coomassie brilliant blue Chemical compound [Na+].C1=CC(OCC)=CC=C1NC1=CC=C(C(=C2C=CC(C=C2)=[N+](CC)CC=2C=C(C=CC=2)S([O-])(=O)=O)C=2C=CC(=CC=2)N(CC)CC=2C=C(C=CC=2)S([O-])(=O)=O)C=C1 NKLPQNGYXWVELD-UHFFFAOYSA-M 0.000 description 2
- 239000003292 glue Substances 0.000 description 2
- 229940097275 indigo Drugs 0.000 description 2
- COHYTHOBJLSHDF-UHFFFAOYSA-N indigo powder Natural products N1C2=CC=CC=C2C(=O)C1=C1C(=O)C2=CC=CC=C2N1 COHYTHOBJLSHDF-UHFFFAOYSA-N 0.000 description 2
- 239000012621 metal-organic framework Substances 0.000 description 2
- 229930187593 rose bengal Natural products 0.000 description 2
- 229940081623 rose bengal Drugs 0.000 description 2
- AZJPTIGZZTZIDR-UHFFFAOYSA-L rose bengal Chemical compound [K+].[K+].[O-]C(=O)C1=C(Cl)C(Cl)=C(Cl)C(Cl)=C1C1=C2C=C(I)C(=O)C(I)=C2OC2=C(I)C([O-])=C(I)C=C21 AZJPTIGZZTZIDR-UHFFFAOYSA-L 0.000 description 2
- STRXNPAVPKGJQR-UHFFFAOYSA-N rose bengal A Natural products O1C(=O)C(C(=CC=C2Cl)Cl)=C2C21C1=CC(I)=C(O)C(I)=C1OC1=C(I)C(O)=C(I)C=C21 STRXNPAVPKGJQR-UHFFFAOYSA-N 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- JPYHHZQJCSQRJY-UHFFFAOYSA-N Phloroglucinol Natural products CCC=CCC=CCC=CCC=CCCCCC(=O)C1=C(O)C=C(O)C=C1O JPYHHZQJCSQRJY-UHFFFAOYSA-N 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
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- -1 and the like Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910001431 copper ion Inorganic materials 0.000 description 1
- 238000009295 crossflow filtration Methods 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910001437 manganese ion Inorganic materials 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- QCDYQQDYXPDABM-UHFFFAOYSA-N phloroglucinol Chemical compound OC1=CC(O)=CC(O)=C1 QCDYQQDYXPDABM-UHFFFAOYSA-N 0.000 description 1
- 229960001553 phloroglucinol Drugs 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/027—Nanofiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0006—Organic membrane manufacture by chemical reactions
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/66—Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
- B01D71/68—Polysulfones; Polyethersulfones
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Nanotechnology (AREA)
- Water Supply & Treatment (AREA)
- Manufacturing & Machinery (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention discloses a hollow fiber composite nanofiltration membrane based on a Covalent Organic Frameworks (COFs) middle layer, a preparation method and application thereof; the preparation method of the hollow fiber composite membrane comprises the steps of preparing a COFs intermediate layer and preparing a separation skin layer; according to the invention, the COFs intermediate layer is generated in situ on the surface of the hollow fiber base membrane, and then interfacial polymerization is carried out on the COFs layer, so that the flux and the interception performance of the composite membrane are remarkably improved due to the introduction of the COFs intermediate layer; the COFs intermediate layer material can improve the physical and chemical properties of the base membrane, and adjust the pore diameter and pore diameter distribution of the membrane, so that the subsequent interfacial polymerization process can be more effectively regulated and controlled, and the separation performance of the composite membrane is greatly improved; the invention has simple preparation process and good application prospect in the aspect of water treatment.
Description
Technical Field
The invention belongs to the technical field of membrane separation, and particularly relates to a hollow fiber composite nanofiltration membrane as well as a preparation method and application thereof.
Background
The nanofiltration membrane separation technology is a novel pressure-driven separation technology, has the advantages of low operating pressure, stable operation, excellent separation performance and the like, and has been widely applied in the fields of seawater desalination, municipal water purification engineering, environmental protection, food industry and the like. The core of the nanofiltration membrane separation technology is a nanofiltration membrane, which comprises a flat plate type and a hollow fiber type. The hollow fiber nanofiltration membrane has the advantages of small amplification effect, high comprehensive performance, high packing density, low membrane pollution degree and the like in practical application, and has a good development prospect in the aspect of industrial application.
The separation performance of the membrane is an important standard for measuring the performance of the membrane, however, most of the membranes prepared in the actual process have a Trade-off effect, namely, the contradiction relationship between permeability and selectivity exists, and the permeability and the selectivity cannot be simultaneously considered, so that the effect of the filter membrane in the actual use process is not good. In order to break the Trade-off effect and effectively improve the performance of the film, researchers mainly adopt the following modes: doping nanoparticles in a separate layer, such as: metal Organic Frameworks (MOFs), covalent Organic Frameworks (COFs), graphene Oxide (GO), carbon Nanotubes (CNTs), and the like, or nanoparticles or other polymers are mixed into a base film to modify the film surface, or an intermediate layer is constructed on the film surface. The introduction of the nano particles generally has the problem of low improvement on the membrane performance due to the agglomeration phenomenon, and the problem does not exist when the nano material intermediate layer is constructed on the surface of the membrane in situ.
Covalent Organic Frameworks (COFs) are organic polymer materials composed of organic elements and connected by covalent bonds, have the characteristics of high specific surface area, porosity, multiple dimensions, low density, strong thermal stability and the like, and have special structure and material characteristics, so that the COFs are paid attention to in the field of membrane separation. Many COFs nano materials are two-dimensional layered structures, and are characterized by having a porous structure with high order, so that the pore structure on the surface of the membrane is easy to regulate and control. By means of multiple advantages of the two-dimensional COFs nano material, the separation performance of the membrane can be regulated and optimized by introducing the COFs structure in the membrane preparation process, so that the Trade-off effect is broken, a thin and defect-free separation skin layer is finally prepared, and the separation performance of the hollow fiber composite nanofiltration membrane is greatly improved.
Disclosure of Invention
The invention provides a hollow fiber composite nanofiltration membrane based on a COFs intermediate layer, a preparation method and application thereof, aiming at a series of technical problems of low flux, poor separation performance, poor stability, slow industrialization and the like of the hollow fiber composite nanofiltration membrane in the prior art.
In order to achieve the above object, the technical solution of the present invention is as follows.
The invention discloses a hollow fiber composite nanofiltration membrane in a first aspect, which comprises a three-layer structure: hollow fiber basement membrane, COFs nano-material intermediate level, separation cortex, wherein:
(1) The COFs nano material intermediate layer is generated by an interface reaction of a water phase monomer and an organic phase monomer which form COFs in situ;
(2) The separation skin layer is an ultrathin polyamide layer generated in situ in an interfacial polymerization mode.
Preferably, the hollow fiber base membrane is a hollow fiber ultrafiltration membrane or a hollow fiber microfiltration membrane, and the material of the hollow fiber base membrane comprises polysulfone and polyethersulfone.
Preferably, the aqueous phase monomer solution constituting the COFs contains an aqueous phase monomer and an additive, and the organic phase monomer solution constituting the COFs contains an organic phase monomer and an organic solvent.
Preferably, the aqueous monomers constituting the COFs comprise p-phenylenediamine (Pa), the organic monomers constituting the COFs comprise 1,3,5-triafol (Tp), and the organic solvent in the organic monomer solution constituting the COFs comprises hexane.
Preferably, the polyamide separation skin layer is prepared by a method of interfacial polymerization of polyamine and polybasic acyl chloride.
Preferably, the average thickness of the polyamide separation skin layer is less than 25 nm, and the average roughness is less than 45 nm.
Preferably, the hollow fiber composite nanofiltration membrane is used for treating 2000mg/L Na at normal temperature and under the transmembrane pressure difference of 0.5MPa 2 SO 4 Na in aqueous solution 2 SO 4 The retention rate of the water-soluble polymer is more than 94 percent, and the water permeability is more than 70L/(m) 2 ·h·MPa)。
Preferably, the hollow fiber composite nanofiltration membrane has the interception rate of NaCl in 2000mg/L NaCl aqueous solution of less than 40% and the water permeability of more than 70L/(m) under the conditions of normal temperature and 0.5MPa of transmembrane pressure difference 2 ·h·MPa)。
Preferably, the hollow fiber composite nanofiltration membrane is used for treating 2000mg/L MgSO at normal temperature and under the transmembrane pressure difference of 0.5MPa 4 MgSO in aqueous solution 4 The retention rate is more than 90 percent, and the water permeability is more than 70L/(m) 2 ·h·MPa)。
Preferably, the hollow fiber composite nanofiltration membrane is used for treating 2000mg/L MgCl at normal temperature and under the transmembrane pressure difference of 0.5MPa 2 MgCl in aqueous solution 2 The retention rate of the water-soluble polymer is less than 80 percent, and the water permeability is more than 70L/(m) 2 ·h·MPa)。
Preferably, the hollow fiber composite nanofiltration membrane has a rejection rate of more than 90% for heavy metal ions in a 2000mg/L heavy metal salt aqueous solution at normal temperature and a transmembrane pressure difference of 0.5 MPa.
Preferably, the hollow fiber composite nanofiltration membrane has the rejection rate of more than 94% for sulfate ions in a mixed salt solution containing sulfate ions and chloride ions and the rejection rate of less than 40% for chloride ions.
The second aspect of the invention discloses a preparation method of a hollow fiber composite nanofiltration membrane, which comprises the following steps:
the method comprises the following steps: firstly, soaking a hollow fiber base membrane in an aqueous phase monomer solution for forming COFs for a certain time, then removing redundant aqueous phase solution on the surface of the base membrane, drying the base membrane, soaking the base membrane in an organic phase monomer solution for forming COFs for a certain time, and then drying the membrane in an atmosphere at a certain temperature for a certain time to finally obtain the hollow fiber base membrane decorated with the ultrathin and uniform COFs nano material intermediate layer;
step two: and (2) firstly contacting the surface of the hollow fiber base membrane of the modified ultrathin and uniform two-dimensional COFs nano material intermediate layer obtained in the step one with a water phase solution of polyamine for a certain time, then airing for a certain time, then contacting with an organic phase solution of polyacyl chloride for a certain time to enable the polyammonium and the polyacyl chloride to generate interfacial polymerization, and then carrying out heat treatment to obtain the hollow fiber composite nanofiltration membrane containing the COFs nano material intermediate layer.
Preferably, the aqueous phase monomer solution constituting the COFs contains an aqueous phase monomer and an additive, and the organic phase monomer solution constituting the COFs contains an organic phase monomer and an organic solvent.
Preferably, the aqueous monomers constituting the COFs comprise p-phenylenediamine (Pa), the organic monomers constituting the COFs comprise 1,3,5-triafol (Tp), and the organic solvent in the organic monomer solution constituting the COFs comprises hexane.
Preferably, the mass percentage concentration range of the water phase monomer in the water phase monomer solution forming the COFs is 0.005% -0.060%: the mass percentage concentration range of the organic phase monomer in the organic phase monomer solution forming the COFs is 0.00025% -0.0030%.
Preferably, the time for soaking the hollow fiber base membrane in an aqueous phase monomer solution forming COFs is 1 s-180 s, the time for soaking the hollow fiber base membrane in an organic phase monomer solution forming COFs is 1 s-90 s, and the drying time of the hollow fiber base membrane decorated with the ultrathin and uniform COFs nano material intermediate layer is 0-30min.
Preferably, the polyamine is diamine, and the polyacyl chloride is tribasic acyl chloride.
Preferably, the polyamine is piperazine or m-phenylenediamine, and the polyacyl chloride is trimesoyl chloride.
Preferably, the contact time of the surface of the COFs nano material interlayer and the aqueous solution of the polyamine is 5 to 60 s; and the surface of the intermediate layer of the COFs nano material is contacted with an aqueous solution of polyamine and dried, and then is contacted with an organic phase solution of polyacyl chloride for 5 to 30 seconds.
The third aspect of the invention discloses an application of a hollow fiber composite nanofiltration membrane, which is used for separating and purifying divalent salt and monovalent salt in an aqueous solution system, or separating and purifying an aqueous solution containing heavy metal salt, or separating and purifying an aqueous solution containing an organic solute, or separating and purifying salt and an organic solute in an aqueous solution system containing salt and the organic solute simultaneously, wherein the molecular weight range of the organic solute is 200 to 2000 daltons.
The technical scheme of the invention achieves obvious technical effect and progress and has substantive characteristics.
Compared with the nanofiltration membrane which is prepared under the same condition and does not contain the nano-material intermediate layer, the composite nanofiltration membrane has the advantages that the salt rejection rate and the water permeability are greatly improved, the sodium sulfate rejection rate is increased from 92% to 96%, and the water permeability can be increased to 48%; the stability of the composite membrane is improved, the application range of the composite membrane is greatly expanded, the obvious technical effect is obtained, and the composite membrane has good application prospect.
The preparation method of the hollow fiber composite nanofiltration membrane has the remarkable technical advantages that the traditional interfacial polymerization technology is combined with the two-dimensional nano material, and the two-dimensional COFs nano material intermediate layer is generated in situ on the surface of the hollow fiber base membrane through the reaction of two monomers. The structure and performance advantages of the two-dimensional COFs nano material are fully utilized, the pore size distribution on the surface of the base membrane is effectively regulated and controlled, the uniform distribution of the water-phase monomer solution on the micro scale of the surface of the middle layer is realized, the interfacial polymerization process is effectively regulated and controlled, the precise regulation and control of the surface micro appearance, the structure and the separation performance of the hollow fiber nanofiltration membrane are realized, and the uniform and defect-free cortex is more favorably generated. The film prepared by the method has good long-term stability, stain resistance, acid and alkali resistance and chlorine resistance; the interfacial polymerization can be carried out at a lower concentration, so that the film preparation cost is reduced, and the resources are saved; the preparation method is simple and easy to operate.
Through the technical innovation, the invention achieves remarkable technical progress and has excellent application prospect in the field of water treatment.
Detailed Description
The invention is further illustrated by the following specific comparative examples and examples.
The basement membrane is a polysulfone (PSf) hollow fiber ultrafiltration membrane;
the water phase monomer forming the Covalent Organic Frameworks (COFs) is p-phenylenediamine (Pa), the organic phase monomer is 1,3,5-triacyl phloroglucinol (Tp), and the organic solvent of the organic phase is n-hexane;
the polyamine compound used for the skin layer interface polymerization reaction is piperazine (PIP), wherein Sodium Dodecyl Sulfate (SDS) and Triethylamine (TEA) are added as additives; the polybasic acyl chloride is 1,3,5-trimesoyl chloride (TMC); the organic solvent is n-hexane;
the membrane separation performance test method adopted by the embodiment of the invention comprises the following steps:
the prepared composite hollow fiber nanofiltration membrane is packaged into a component for separation performance test, and all tests adopt the same operating conditions for comparison: normal temperature, transmembrane pressure difference of 0.5MPa, same and constant feed flow and cross flow filtration. The solute comprises inorganic salt, dye and heavy metal salt, which are all prepared into solution with single solute. The inorganic salt includes NaCl and Na 2 SO 4 、MgSO 4 、MgCl 2 . The concentration of the inorganic salt used was 2000 mg/L; the concentration of the dye used was 100 mg/L; the concentration of the heavy metal salt used was 2000mg/L. The test performance is expressed in terms of the rejection of the solute and the corresponding water flux or water permeability, the ratio of water flux to the transmembrane pressure difference representing the water permeability. The method for representing the retention rate and the water flux is a common method in the field.
Comparative example:
preparing PIP aqueous solution by using deionized water, wherein the components of the PIP aqueous solution are as follows: 0.75 PIP in% by mass, TEA in 2.0% by mass, and SDS in 0.1% by mass;
the TMC is dissolved in n-hexane to prepare 0.15 wt% TMC organic phase solution.
The preparation method of the polypiperazine amide composite hollow fiber nanofiltration membrane comprises the following steps and conditions:
a pretreatment step: soaking the hollow fiber base membrane subjected to the sealing glue treatment at two ends in deionized water for 12 hours;
interfacial polymerization step for separating skin layer: taking out the base film from the deionized water, airing the water on the surface of the base film, and fully contacting the surface of the base film with a PIP aqueous solution to obtain 60 s; removing the PIP aqueous solution on the surface of the base film, and airing the film in the air at room temperature; fully contacting the surface of the dried base film with 30 s of TMC organic phase solution; then, removing the TMC organic phase solution on the surface of the membrane, and quickly putting the membrane into a drying oven at 80 ℃ for drying for 5 min; and finally, taking out the membrane, and naturally airing the membrane in a dry environment to obtain the polypiperazine-amide composite hollow fiber nanofiltration membrane with the outer skin layer in a dry state.
The separation performance test result of the prepared hollow fiber nanofiltration membrane is as follows:
for 2000mg/L Na 2 SO 4 Na in aqueous solution 2 SO 4 The retention rate of (A) is 92.9%, and the water permeability is 58.3L/(m) 2 ·h·MPa)。
The NaCl retention rate of the NaCl solution of 2000mg/L is 29.31 percent, and the water permeability is 66.4L/(m) 2 ·h·MPa)。
MgSO for 2000mg/L 4 MgSO in aqueous solution 4 The retention rate of (1) is 90.8%, and the water permeability is 57.8L/(m) 2 ·h·MPa)。
MgCl for 2000mg/L 2 MgCl in aqueous solution 2 The retention rate of the membrane is 58.03 percent, and the water permeability is 57.6L/(m) 2 ·h·MPa)。
Example 1
And (3) preparing a Pa water solution with the mass percent concentration of 0.020% and a Tp solution with the mass percent concentration of 0.0010%.
The film preparation steps are as follows:
the method comprises the following steps: soaking a prepared hollow fiber ultrafiltration base membrane subjected to sealing glue treatment at two ends in deionized water for 12 hours, taking out water on the surface of the hollow fiber ultrafiltration base membrane, soaking the hollow fiber base membrane in a Pa aqueous solution for 60 s, removing redundant aqueous phase solution on the surface of the base membrane, drying the base membrane, soaking the base membrane in a Tp organic phase solution for 15 s, drying the membrane in an atmosphere at a certain temperature for 5 minutes, and finally obtaining the ultrathin and uniform hollow fiber polysulfone base membrane modified by the two-dimensional COFs intermediate layer;
step two: and (3) separating interfacial polymerization of the skin layer, performing interfacial polymerization on the surface of the intermediate layer containing the COFs, and obtaining the polypiperazine amide hollow fiber composite nanofiltration membrane of the outer skin layer containing the COFs intermediate layer by adopting the same interfacial polymerization step as the comparative example.
The separation performance test result of the prepared hollow fiber nanofiltration membrane containing the COFs middle layer is as follows:
for Na 2 SO 4 The retention rate of (A) is 96.6%, and the water permeability is 86.6L/(m) 2 h.MPa) compared with the comparative example, the water permeability is greatly improved, and the water permeability is improved by 48.5 percent.
The NaCl retention rate of the NaCl solution of 2000mg/L is 38.9 percent, and the water permeability is 93.8L/(m) 2 ·h·MPa)。
MgSO for 2000mg/L 4 MgSO in aqueous solution 4 The retention rate of (A) is 92.3%, and the water permeability is 78.8L/(m) 2 ·h·MPa)。
MgCl for 2000mg/L 2 MgCl in aqueous solution 2 The retention rate of (2) is 73.0%, and the water permeability is 73.0L/(m) 2 ·h·MPa)。
The retention rate of Cang Gong T molecules in 100 mg/L Cang Gong T (molecular weight is 350 daltons) aqueous solution is 90.8%; the retention rate of the indigo disulfonic acid sodium molecules in 100 mg/L indigo disulfonic acid sodium (with the molecular weight of 466 daltons) aqueous solution is 93.5%; the rejection rate of the Coomassie brilliant blue molecules in 100 mg/L Coomassie brilliant blue (with the molecular weight of 854 daltons) aqueous solution is 97.2 percent; the retention rate of rose bengal molecules in 100 mg/L rose bengal (with a molecular weight of 1017 daltons) aqueous solution is 98.7%.
For Cr of 2000mg/L 2 (SO 4 ) 3 The rejection rate of heavy metal chromium ions in the aqueous solution is 95.4 percent; for CuSO of 2000mg/L 4 Of heavy metal copper ions in aqueous solutionThe retention rate is 94.3%; for 2000mg/L ZnSO 4 The rejection rate of heavy metal zinc ions in the aqueous solution is 91.7 percent; for MnSO of 2000mg/L 4 The interception rates of heavy metal manganese ions in the aqueous solution reach 91.0 percent respectively.
The prepared hollow fiber nanofiltration membrane containing the COFs intermediate layer has good pollution resistance, acid and alkali resistance and chlorine resistance, and the average thickness of a separation skin layer of the composite membrane is 20 nm.
Example 2
The difference from example 1 is that: the reaction time of the Pa monomer and the Tp monomer in the first step is 30 s.
All other steps are the same as in example 1;
the separation performance test result of the prepared hollow fiber nanofiltration membrane containing the COFs intermediate layer is as follows:
prepared polypiperazine amide hollow fiber composite nanofiltration membrane pair Na 2 SO 4 Has a retention rate of 94.5% and a water permeability of 72.4L/(m) 2 h.MPa). Compared with a comparative example, the flux is greatly improved, and the water permeability is improved by 23.9%.
Example 3
The difference from example 1 is that: and in the first step, the drying time of the membrane surface after the Pa monomer and the Tp monomer react is 5 min.
All other steps are the same as in example 1;
the separation performance test result of the prepared hollow fiber nanofiltration membrane containing the COFs intermediate layer is as follows:
prepared polypiperazine amide hollow fiber composite nanofiltration membrane pair Na 2 SO 4 The retention rate of (A) is 95.5%, and the water permeability is 76.2L/(m) 2 h.MPa). Compared with a comparative example, the flux is greatly improved, and the water permeability is improved by 30.7%.
Example 4
The difference from example 1 is that: the mass concentration of PIP in the interfacial polymerization condition in the second step is 1.0 wt%.
All other steps are the same as in example 1;
the separation performance test result of the prepared hollow fiber nanofiltration membrane containing the COFs middle layer is as follows:
prepared polypiperazine amide hollow fiber composite nanofiltration membrane pair Na 2 SO 4 The retention rate of (A) is 97.1%, and the water permeability is 76.5L/(m) 2 h.MPa). Compared with a comparative example, the flux is greatly improved, and the water permeability is improved by 31.2 percent.
The above examples illustrate that the two-dimensional TpPa intermediate layer is generated in situ on the base film, which has a great influence on the interfacial polymerization process, and the introduction of the two-dimensional nano-materials COFs intermediate layer effectively regulates the interfacial polymerization process and the structure of the separation layer, so that the separation performance of the film is greatly improved. The invention achieves remarkable technical effects and progress.
It should be noted that the above-mentioned embodiments illustrate only preferred specific embodiments of the invention, and are not to be construed as limiting the invention, any embodiments falling within the scope of the invention, which is defined by the features of the claims or the equivalents thereof, constituting a right to infringe the invention.
Claims (20)
1. The utility model provides a hollow fiber composite nanofiltration membrane which characterized in that includes three layer construction: hollow fiber basement membrane, COFs nano-material intermediate level, separation cortex, wherein:
the COFs nano material intermediate layer is generated by an interface reaction of a water phase monomer and an organic phase monomer which form COFs in situ;
the separation skin layer is an ultrathin polyamide layer generated in situ in an interfacial polymerization mode.
2. The composite nanofiltration membrane according to claim 1, wherein the hollow fiber membrane is a hollow fiber ultrafiltration membrane or a hollow fiber microfiltration membrane, and the hollow fiber membrane is made of polysulfone and polyethersulfone.
3. The hollow fiber composite nanofiltration membrane of claim 1, wherein the aqueous phase monomer solution constituting the COFs comprises an aqueous phase monomer and an additive, and the organic phase monomer solution constituting the COFs comprises an organic phase monomer and an organic solvent.
4. The hollow fiber composite nanofiltration membrane according to claim 1 or 2, wherein the aqueous phase monomers forming the COFs comprise p-phenylenediamine (Pa), the organic phase monomers forming the COFs comprise 1,3,5-tri-benzoyl phloroglucinol (Tp), and the organic solvent in the organic phase monomer solution forming the COFs comprises hexane.
5. The hollow fiber composite nanofiltration membrane according to claim 1, wherein the polyamide separation skin layer is prepared by interfacial polymerization of polyamine and polyacyl chloride.
6. The hollow fiber composite nanofiltration membrane of claim 1, wherein the average thickness of the polyamide separation skin layer is less than 25 nm, and the average roughness is less than 45 nm.
7. The hollow fiber composite nanofiltration membrane of claim 1, wherein the hollow fiber composite nanofiltration membrane is used for treating 2000mg/L Na at normal temperature and a transmembrane pressure difference of 0.5MPa 2 SO 4 Na in aqueous solution 2 SO 4 The retention rate of the water-soluble polymer is more than 94 percent, and the water permeability is more than 70L/(m) 2 ·h·MPa)。
8. The hollow fiber composite nanofiltration membrane of claim 1, wherein the rejection rate of the hollow fiber composite nanofiltration membrane on NaCl in a 2000mg/L NaCl aqueous solution is less than 40% and the water permeability is greater than 70L/(m) under the conditions of normal temperature and 0.5MPa of transmembrane pressure difference 2 ·h·MPa)。
9. The composite nanofiltration membrane of claim 1, wherein the pressure difference between the hollow fiber and the nanofiltration membrane is 0.5MPa at room temperature2000 mg/L MgSO 4 MgSO in aqueous solution 4 The retention rate is more than 90 percent, and the water permeability is more than 70L/(m) 2 ·h·MPa)。
10. The hollow fiber composite nanofiltration membrane of claim 1, wherein the rejection rate of the hollow fiber composite nanofiltration membrane on heavy metal ions in a 2000mg/L heavy metal salt water solution is more than 90% at normal temperature and a transmembrane pressure difference of 0.5 MPa.
11. The hollow fiber composite nanofiltration membrane according to claim 1, wherein the rejection rate of the hollow fiber composite nanofiltration membrane on sulfate ions in a mixed salt solution containing sulfate ions and chloride ions is greater than 94%, and the rejection rate on chloride ions is less than 40%.
12. The preparation method of the hollow fiber composite nanofiltration membrane is characterized by comprising the following steps of:
the method comprises the following steps: firstly, soaking a hollow fiber base membrane in an aqueous phase monomer solution for forming COFs (chemical on glass) for a certain time, then, removing redundant aqueous phase solution on the surface of the base membrane, airing, soaking the base membrane in an organic phase monomer solution for forming COFs for a certain time, and then, drying the membrane in an atmosphere at a certain temperature for a certain time to finally obtain the hollow fiber base membrane decorated with an ultrathin and uniform COFs nano material intermediate layer;
step two: and (2) firstly contacting the surface of the hollow fiber base membrane of the modified ultrathin and uniform two-dimensional COFs nano material intermediate layer obtained in the step one with a water phase solution of polyamine for a certain time, then airing for a certain time, then contacting with an organic phase solution of polyacyl chloride for a certain time to enable the polyammonium and the polyacyl chloride to generate interfacial polymerization, and then carrying out heat treatment to obtain the hollow fiber composite nanofiltration membrane containing the COFs nano material intermediate layer.
13. The method of claim 12, wherein the aqueous monomer solution constituting the COFs contains an aqueous monomer and an additive, and the organic monomer solution constituting the COFs contains an organic monomer and an organic solvent.
14. The method as claimed in claim 12 or 13, wherein the aqueous phase monomer constituting the COFs comprises p-phenylenediamine (Pa), the organic phase monomer constituting the COFs comprises 1,3,5-tria (Tp), and the organic solvent in the organic phase monomer solution constituting the COFs comprises hexane.
15. The method for preparing a hollow fiber composite nanofiltration membrane according to claim 12, wherein the concentration of the aqueous phase monomer in the aqueous phase monomer solution constituting the COFs is in a range from 0.005% to 0.060% by mass: the mass percentage concentration range of the organic phase monomer in the organic phase monomer solution forming the COFs is 0.00025% -0.0030%.
16. The preparation method of the hollow fiber composite nanofiltration membrane of claim 12, wherein the hollow fiber base membrane is soaked in an aqueous monomer solution forming COFs for 1 s to 180 s, the hollow fiber base membrane is soaked in an organic monomer solution forming COFs for 1 s to 90 s, and the drying time of the hollow fiber base membrane decorated with the ultrathin and uniform COFs nanomaterial middle layer is 0 to 30min.
17. The method for preparing a hollow fiber composite nanofiltration membrane comprising a COFs nanomaterial interlayer according to claim 12, wherein the polyamine is diamine, and the poly acid chloride is tribasic acid chloride.
18. The hollow fiber composite nanofiltration membrane comprising the COFs nanomaterial interlayer according to claim 12, wherein the polyamine is piperazine or m-phenylenediamine, and the poly-acid chloride is trimesoyl chloride.
19. The method for preparing the hollow fiber composite nanofiltration membrane according to claim 12, wherein the contact time of the surface of the intermediate layer of the COFs nano material and an aqueous solution of polyamine is 5-60 s; and the surface of the intermediate layer of the COFs nano material is contacted with an aqueous solution of polyamine and dried, and then is contacted with an organic phase solution of polyacyl chloride for 5 to 30 seconds.
20. An application of a hollow fiber composite nanofiltration membrane, which is used for separating and purifying divalent salt and monovalent salt in an aqueous solution system, or separating and purifying an aqueous solution containing heavy metal salt, or separating and purifying an aqueous solution containing an organic solute, or separating and purifying salt and an organic solute in an aqueous solution system containing salt and an organic solute simultaneously, wherein the molecular weight of the organic solute is 200 to 2000 daltons, and the hollow fiber composite nanofiltration membrane is the hollow fiber composite nanofiltration membrane according to any one of claims 1 to 11, or the hollow fiber composite nanofiltration membrane prepared by the preparation method according to any one of claims 12 to 19.
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