CN114432907B - Composite nanofiltration membrane with ultrahigh lithium magnesium selectivity and preparation method and application thereof - Google Patents
Composite nanofiltration membrane with ultrahigh lithium magnesium selectivity and preparation method and application thereof Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims abstract description 229
- 238000001728 nano-filtration Methods 0.000 title claims abstract description 100
- GCICAPWZNUIIDV-UHFFFAOYSA-N lithium magnesium Chemical compound [Li].[Mg] GCICAPWZNUIIDV-UHFFFAOYSA-N 0.000 title claims abstract description 97
- 239000002131 composite material Substances 0.000 title claims abstract description 85
- 238000002360 preparation method Methods 0.000 title claims abstract description 25
- 239000000243 solution Substances 0.000 claims abstract description 151
- 239000000178 monomer Substances 0.000 claims abstract description 132
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 128
- 238000000108 ultra-filtration Methods 0.000 claims abstract description 85
- 238000000926 separation method Methods 0.000 claims abstract description 71
- 229920000768 polyamine Polymers 0.000 claims abstract description 64
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 49
- 239000002070 nanowire Substances 0.000 claims abstract description 49
- 239000004094 surface-active agent Substances 0.000 claims abstract description 37
- 239000004952 Polyamide Substances 0.000 claims abstract description 29
- 229920002647 polyamide Polymers 0.000 claims abstract description 29
- 230000004907 flux Effects 0.000 claims abstract description 28
- 238000006243 chemical reaction Methods 0.000 claims abstract description 24
- 238000012695 Interfacial polymerization Methods 0.000 claims abstract description 22
- 239000008346 aqueous phase Substances 0.000 claims abstract description 21
- 239000012267 brine Substances 0.000 claims abstract description 20
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 20
- 238000009792 diffusion process Methods 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 14
- 239000012074 organic phase Substances 0.000 claims abstract description 14
- 230000009881 electrostatic interaction Effects 0.000 claims abstract description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 150000001263 acyl chlorides Chemical class 0.000 claims description 56
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 50
- 229920000962 poly(amidoamine) Polymers 0.000 claims description 43
- 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 36
- 239000011777 magnesium Substances 0.000 claims description 35
- 239000002121 nanofiber Substances 0.000 claims description 33
- 230000014759 maintenance of location Effects 0.000 claims description 31
- 229920002873 Polyethylenimine Polymers 0.000 claims description 23
- 229910052708 sodium Inorganic materials 0.000 claims description 23
- 239000011734 sodium Substances 0.000 claims description 23
- 229920002749 Bacterial cellulose Polymers 0.000 claims description 22
- 239000005016 bacterial cellulose Substances 0.000 claims description 22
- 238000004519 manufacturing process Methods 0.000 claims description 20
- 229920002492 poly(sulfone) Polymers 0.000 claims description 17
- 239000011148 porous material Substances 0.000 claims description 16
- 238000000605 extraction Methods 0.000 claims description 15
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 10
- 229910052749 magnesium Inorganic materials 0.000 claims description 10
- 239000012071 phase Substances 0.000 claims description 10
- 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 claims description 9
- 239000004695 Polyether sulfone Substances 0.000 claims description 9
- 229920006393 polyether sulfone Polymers 0.000 claims description 9
- 238000002791 soaking Methods 0.000 claims description 9
- 229920001328 Polyvinylidene chloride Polymers 0.000 claims description 8
- 150000002500 ions Chemical class 0.000 claims description 8
- 239000005033 polyvinylidene chloride Substances 0.000 claims description 8
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 6
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 6
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 6
- 239000003054 catalyst Substances 0.000 claims description 6
- 229920002678 cellulose Polymers 0.000 claims description 6
- 239000001913 cellulose Substances 0.000 claims description 6
- 239000003960 organic solvent Substances 0.000 claims description 6
- 239000002109 single walled nanotube Substances 0.000 claims description 6
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- 239000002048 multi walled nanotube Substances 0.000 claims description 3
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 3
- 229960000776 sodium tetradecyl sulfate Drugs 0.000 claims description 3
- 239000000758 substrate Substances 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
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 2
- PWAXUOGZOSVGBO-UHFFFAOYSA-N adipoyl chloride Chemical compound ClC(=O)CCCCC(Cl)=O PWAXUOGZOSVGBO-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
- 229940018564 m-phenylenediamine Drugs 0.000 claims description 2
- LXEJRKJRKIFVNY-UHFFFAOYSA-N terephthaloyl chloride Chemical compound ClC(=O)C1=CC=C(C(Cl)=O)C=C1 LXEJRKJRKIFVNY-UHFFFAOYSA-N 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 1
- 229910000861 Mg alloy Inorganic materials 0.000 claims 1
- 239000004745 nonwoven fabric Substances 0.000 claims 1
- 229920000642 polymer Polymers 0.000 claims 1
- UPUIQOIQVMNQAP-UHFFFAOYSA-M sodium;tetradecyl sulfate Chemical compound [Na+].CCCCCCCCCCCCCCOS([O-])(=O)=O UPUIQOIQVMNQAP-UHFFFAOYSA-M 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 4
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 4
- 239000010408 film Substances 0.000 description 65
- 239000007864 aqueous solution Substances 0.000 description 33
- 238000012360 testing method Methods 0.000 description 33
- 150000003839 salts Chemical class 0.000 description 27
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 24
- 239000008367 deionised water Substances 0.000 description 17
- 229910021641 deionized water Inorganic materials 0.000 description 17
- -1 sodium alkyl sulfate Chemical class 0.000 description 16
- 230000000694 effects Effects 0.000 description 11
- 238000005265 energy consumption Methods 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 230000033228 biological regulation Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 4
- 230000002401 inhibitory effect Effects 0.000 description 3
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- 230000002829 reductive effect Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 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 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- JYFHYPJRHGVZDY-UHFFFAOYSA-N Dibutyl phosphate Chemical compound CCCCOP(O)(=O)OCCCC JYFHYPJRHGVZDY-UHFFFAOYSA-N 0.000 description 1
- 229910006309 Li—Mg Inorganic materials 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 239000003945 anionic surfactant Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
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- 230000007774 longterm Effects 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 150000007519 polyprotic acids Polymers 0.000 description 1
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- 238000012216 screening Methods 0.000 description 1
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- 239000000126 substance Substances 0.000 description 1
Images
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—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
- 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
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0083—Thermal after-treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/10—Supported membranes; Membrane supports
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/56—Polyamides, e.g. polyester-amides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
- C22B26/10—Obtaining alkali metals
- C22B26/12—Obtaining lithium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
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Abstract
The invention discloses a composite nanofiltration membrane with ultrahigh lithium magnesium selectivity, and a preparation method and application thereof. The preparation method comprises the following steps: the surface of a porous ultrafiltration support bottom film is used as an interface between an aqueous phase solution containing polyamine monomers, a surfactant and nanowires and an organic phase solution containing polyacyl chloride monomers, so that the polyamine monomers and the surfactant molecules are gathered at the interface through a first electrostatic interaction force, the nanowires give a second electrostatic interaction force to the second electrostatic interaction force and limit the upward diffusion of the polyamine monomers, the polyamine monomers and the polyacyl chloride monomers are subjected to interfacial polymerization reaction at the interface to form a compact polyamide separation and selection layer, and the compact polyamide separation and selection layer is subjected to heat treatment to obtain the composite nanofiltration film with ultrahigh lithium-magnesium selectivity. The composite nanofiltration membrane has excellent lithium-magnesium separation performance, has an enrichment function on lithium ions, and has pure water flux up to 15.09Lm ‑2 h ‑1 The method has wide application prospect in the field of extracting lithium from brine.
Description
Technical Field
The invention relates to a nanofiltration membrane, in particular to a film composite nanofiltration membrane with ultrahigh lithium magnesium selectivity, a preparation method thereof and application of the film composite nanofiltration membrane, and belongs to the technical field of materials and water treatment.
Background
As an energy metal of an important element for promoting the world to advance, lithium has important significance for the development of national economy, and the demand of various industries such as glass, electric appliances, pharmacy and the like on lithium resources is greatly improved at present. The traditional lithium extraction method is to extract lithium from ores, but the process is complex, the energy consumption is high, the ore storage capacity is increasingly reduced, and the development of global lithium ores is mainly in the form of salt lakes at present. However, since lithium and magnesium in a salt lake are symbiotic, and the chemical properties of magnesium ions and lithium ions are similar, the difference of ionic hydration radii is small, and in order to realize effective extraction of lithium from the salt lake, the problem of lithium-magnesium separation is solved first.
The salt lakes of China are intensively distributed in Qinghai-Tibet plateau areas, the Qinghai-salt lakes generally have the characteristics of high lithium-magnesium ratio and low lithium content, and the main extraction technology comprises the following steps: extraction, adsorption, electrodialysis and nanofiltration. However, these processes have some drawbacks such as high energy consumption, low economic efficiency, environmental friendliness, or inapplicability to salt lakes with high magnesium-lithium ratios. The separation size of the nanofiltration membrane is between ultrafiltration and reverse osmosis, and multivalent ions can be effectively intercepted and monovalent ions can be effectively permeated. The unique advantages of simple selective separation and operation, low cost and environmental protection determine the importance of the nanofiltration method in the field of lithium extraction in salt lakes.
The separation principle of the nanofiltration membrane mainly comprises size screening and charge rejection, and the nanofiltration membrane with proper pore diameter and charging property is designed and prepared aiming at different separation systems and target products so as to realize high-selectivity separation. Because the ionic hydration radius of lithium magnesium is very close, the charge repulsive effect is more remarkable, and the positively charged membrane shows more excellent lithium magnesium separation selectivity. Most of the modification methods now improve the chargeability of the membrane, but this can result in high lithium ion interception. The intention is to extract lithium, but the white loss is substantial. The nanofiltration method is applied to the field of lithium-magnesium separation, and has a great improvement space.
Therefore, how to optimize the polymerization system, a new technology for preparing the thin film composite nanofiltration membrane with high separation selectivity and low lithium interception is sought, and the method has strong research significance and is also the direction of the research efforts.
Disclosure of Invention
The invention mainly aims to provide a composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity and a preparation method thereof, and simultaneously has high separation selectivity and low lithium interception rate so as to overcome the defects of the prior art.
The invention also aims to provide the application of the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity in the field of water treatment.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a preparation method of a composite nanofiltration membrane with ultrahigh lithium magnesium selectivity, which comprises the following steps:
providing a porous ultrafiltration support membrane;
the surface of the porous ultrafiltration support base film is used as an interface between an aqueous phase solution containing polyamine monomers, a surfactant and nano wires and an organic phase solution containing polybasic acyl chloride monomers, so that the polyamine monomers and the surfactant molecules in the porous ultrafiltration support base film are gathered at the interface through a first electrostatic interaction force, the nano wires give a second electrostatic interaction force to the porous ultrafiltration support base film and limit upward diffusion of the polyamine monomers, so that the polyamine monomers and the polybasic acyl chloride monomers perform interfacial polymerization reaction at the interface, a compact polyamide separation selection layer is formed on the surface of the porous ultrafiltration support base film, and then the porous ultrafiltration support base film is subjected to heat treatment, so that the composite nanofiltration film with ultrahigh lithium magnesium selectivity is obtained.
The embodiment of the invention also provides the composite nanofiltration membrane with ultrahigh lithium magnesium selectivity prepared by the preparation method, which comprises a porous ultrafiltration support bottom membrane and a polyamide selective separation layer arranged on the porous ultrafiltration support bottom membrane.
The embodiment of the invention also provides application of the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity in the fields of multivalent/monovalent salt separation or brine extraction and the like.
Correspondingly, the embodiment of the invention also provides a method for extracting lithium from brine, which comprises the following steps:
fully contacting brine with the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity to ensure that Li in the brine + 、Mg 2+ And separating to realize extraction of lithium in brine.
Compared with the prior art, the invention has the following beneficial effects:
1) The ultra-high lithium magnesium selective membrane composite nanofiltration membrane provided by the invention adopts the aqueous solution of the polyamine monomer/surfactant and the nanowire as the water phase and the oil phase of the polyacyl chloride monomer to carry out interfacial polymerization, thus obtaining the membrane composite nanofiltration membrane with ultra-high lithium magnesium selectivity, which has excellent lithium magnesium separation performance, has enrichment effect on lithium ions, and simultaneously has the flux to pure water as high as 15.09Lm -2 h -1 The membrane composite nanofiltration membrane with ultrahigh interception, high selectivity and low energy consumption has great application value in the aspects of multivalent/monovalent salt separation or brine extraction and the like;
2) The preparation method of the ultrahigh lithium magnesium selective membrane composite nanofiltration membrane provided by the invention is simple, and the ultrahigh interception and high selectivity of the nanofiltration membrane can greatly reduce the energy consumption cost when the nanofiltration membrane is applied to the aspects of multivalent/monovalent salt separation or brine extraction and the like, and the process is easy to realize the large-scale production and has high industrial application value.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.
FIGS. 1 and 2 are molecular weight cut-off and pore size distribution diagrams of the membrane surface after interfacial polymerization with and without nanowires added to the aqueous phase in example 10 of the present invention;
FIG. 3 is an SEM image of the surface of an ultra-high Li-Mg selective composite nanofiltration membrane after interfacial polymerization with nanowires added to the water phase in example 10 of the present invention.
Detailed Description
In view of the defects in the prior art, the inventor discovers that the nanowire can play a role in inhibiting the diffusion of a polyamine monomer through the electrostatic effect through long-term research and a large number of practices, and based on the discovery, the inventor provides a preparation method of an ultrahigh lithium magnesium selective thin film composite nanofiltration membrane under the condition of using a surfactant and the nanowire for common regulation. The technical scheme, the implementation process, the principle and the like are further explained as follows.
One aspect of an embodiment of the present invention provides a composite nanofiltration membrane with ultra-high lithium magnesium selectivity, comprising: the porous ultrafiltration support bottom membrane and the polyamide separation and selection layer are arranged on the porous ultrafiltration support bottom membrane, wherein the polyamide separation and selection layer is mainly formed by interfacial polymerization reaction of a polyamine monomer and a polyacyl chloride monomer under the common regulation and control of a surfactant and nanowires, the surfactant comprises sodium alkyl sulfate, and the nanowires comprise nanofibers.
In some preferred embodiments, the surfactant includes sodium alkyl sulfate, and preferably may include any one or a combination of two or more of sodium octaalkyl sulfate, sodium dodecyl sulfate, sodium tetradecyl sulfate, etc., but is not limited thereto.
In some preferred embodiments, the nanowires include nanofibers, and preferably may include any one or a combination of two or more of bacterial cellulose nanofibers, sulfonated cellulose nanofibers, single wall carbon nanotubes, multi wall carbon nanotubes, and the like, but are not limited thereto.
The alkyl sodium sulfate is used as a water-soluble anionic surfactant, and is added into a water phase to participate in the reaction, so that the upward diffusion of a polyamine monomer can be promoted, and meanwhile, the nanowire can weakly limit the diffusion of the polyamine monomer, so that the effect of accurate regulation and control is achieved, and the formed compact polyamide nanofiltration membrane has ultrahigh lithium-magnesium selectivity and has an enrichment effect on lithium.
More specifically, the invention provides a film composite nanofiltration membrane which is regulated and controlled by sodium alkyl sulfate and nanowires and has high separation selectivity and lithium enrichment effect, and the film composite nanofiltration membrane comprises a porous support bottom membrane for providing mechanical support and a polyamide selective separation layer which is arranged on the porous support bottom membrane and has the selective separation effect, wherein the polyamide selective separation layer is mainly formed by interfacial polymerization reaction of a polyamine monomer solution containing a surfactant and the nanowires and a polybasic acyl chloride monomer solution, and the polyamine monomer and the surfactant are aggregated at an interface through electrostatic interaction.
Further, the polyamide selective separation layer is mainly prepared by interfacial polymerization reaction of a polyamine monomer solution containing a surfactant and a nanowire and a polybasic acyl chloride monomer solution, wherein the nanowire has a slight limiting effect on the diffusion of the polyamine monomer, has an accurate regulation and control effect, and can effectively improve the performance of the nanofiltration membrane.
In some embodiments, the polybasic acid chloride monomer may include any one or a combination of two or more of trimesoyl chloride, isophthaloyl chloride, adipoyl chloride, terephthaloyl chloride, and the like, but is not limited thereto.
In some embodiments, the polyamine monomer may include any one or a combination of two or more of piperazine, polyethyleneimine, m-phenylenediamine, dendritic polyamidoamine, and the like, but is not limited thereto.
In some embodiments, the polyamide selective separation layer has a thickness of 20 to 60nm.
In some embodiments, the porous ultrafiltration support base membrane may be any one or a combination of two or more of a polyethersulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, a polysulfone ultrafiltration membrane, a sulfonated polysulfone ultrafiltration membrane, and a polyvinylidene chloride ultrafiltration membrane, and is preferably a polyethersulfone ultrafiltration membrane, but is not limited thereto.
Further, the pore diameter of the pores contained in the porous ultrafiltration support bottom membrane is 5-100 nm.
In some embodiments, the polyamide selective separation layer of the composite nanofiltration membrane has a pore size of 0.550nm or more, preferably 0.550-0.560 nm.
In some embodiments, the polyamide selective separation layer has a molecular weight cut-off (MWCO) size above 160Da, preferably 180-200 Da.
Further, the ultra-high lithium magnesium selective film composite nanofiltration membrane comprises a porous support bottom membrane and a polyamide selective separation layer with the aperture of 0.27-0.30 nm.
The ultra-high lithium magnesium selectivity film composite nanofiltration membrane provided by the invention has basically unchanged pore size distribution (d p About 0.560 nm) slightly increases the molecular weight cut-off (MWCO about 190 Da), the crosslinking density of the polyamide separation layer is substantially unchanged, the surface potential is substantially unchanged, and the molecular weight cut-off for monovalent cations Li is greatly reduced + Thereby greatly improving the separation factor (S) Mg，Li About 100).
In some embodiments, the porous ultrafiltration support backing membrane is further provided with a nonwoven substrate, i.e., alternatively, the ultrafiltration porous support backing membrane may be nonwoven-backed or nonwoven-backed.
In some embodiments, the polyamide separation selection layer pair Mg 2+ The retention rate of the ions is more than 96%, preferably more than 98%; for Li + The rejection rate of ions is less than 30%, preferably less than 28%.
Further, the polyamide selective separation layer is in a mixed solution with a magnesium-lithium ratio of 21.4:1, mg 2+ The retention rate of (2) is greater than 96%, preferably more than 98%; li (Li) + The retention rate of the lithium-magnesium separation is less than-90%, preferably less than-100%, and the separation factor of the lithium-magnesium separation is more than 90%, preferably more than 100.
In some embodiments, the flux of the thin film composite nanofiltration membrane prepared at the surfactant and the nanowires to pure water is 10Lm -2 h -1 Above, preferably at 15Lm -2 h -1 The above; compared with the nanofiltration membrane prepared by no surfactant and nanowire, the pure water flux of the nanofiltration membrane is 10Lm -2 h -1 The pure water flux of the modified membrane is higher than that of the unmodified membrane. The membrane composite nanofiltration membrane with ultrahigh separation factor, high interception and low energy consumption has great application value in the aspects of multivalent/monovalent salt separation or brine extraction and the like.
In conclusion, the ultrahigh lithium magnesium selective membrane composite nanofiltration membrane provided by the invention has ultrahigh separation selectivity on lithium magnesium and higher pure water permeation flux. The ultra-high lithium magnesium selective membrane composite nanofiltration membrane provided by the invention adopts the aqueous solution of the polyamine monomer/surfactant and the nanowire as the aqueous phase and the oil phase of the polybasic acyl chloride monomer to carry out interfacial polymerization, the surfactant and the nanowire jointly regulate and control the diffusion process of the polyamine monomer, and the membrane composite nanofiltration membrane with ultra-high separation factor and high interception is obtained, the pore diameter is accurately regulated and controlled, the narrower pore diameter distribution is maintained, and the separation selectivity is improved.
The preparation method of the composite nanofiltration membrane with ultrahigh lithium magnesium selectivity provided by the other aspect of the embodiment of the invention comprises the following steps: and (3) performing interfacial polymerization reaction on the polyamine monomer and the polybasic acyl chloride monomer under the regulation and control of a surfactant and a nanowire, so that a compact polyamide selective separation layer is formed on the surface of the porous ultrafiltration support base membrane, and then, performing aftertreatment to obtain the composite nanofiltration membrane.
In some embodiments, the preparation method specifically includes:
providing a porous ultrafiltration support membrane;
the surface of the porous ultrafiltration support base film is used as an interface between an aqueous phase solution containing polyamine monomers, a surfactant and nano wires and an organic phase solution containing polybasic acyl chloride monomers, so that the polyamine monomers and the surfactant molecules in the porous ultrafiltration support base film are gathered at the interface through a first electrostatic interaction force, the nano wires give a second electrostatic interaction force to the porous ultrafiltration support base film and limit upward diffusion of the polyamine monomers, so that the polyamine monomers and the polybasic acyl chloride monomers perform interfacial polymerization reaction at the interface, a compact polyamide separation selection layer is formed on the surface of the porous ultrafiltration support base film, and then the porous ultrafiltration support base film is subjected to heat treatment, so that the composite nanofiltration film with ultrahigh lithium magnesium selectivity is obtained.
In some embodiments, the preparation method specifically comprises:
providing an aqueous phase solution containing a polyamine monomer, a surfactant, and a nanowire, and an organic phase solution containing a polyacyl chloride monomer, respectively, wherein the surfactant comprises sodium alkyl sulfate, and the nanowire comprises nanofibers;
And (2) under the conditions of 50-70% of relative humidity and 20-30 ℃ of ambient temperature, enabling an aqueous phase solution containing polyamine monomers, surfactants and nanowires to be in contact with the surface of the porous ultrafiltration support base membrane, fully soaking for 10-150 s, preferably 60-90 s, adding an organic phase solution containing polybasic acyl chloride monomers to the surface of the porous ultrafiltration support base membrane, soaking for 30-120 s, preferably 30-60 s, enabling the polyamine monomers and the polybasic acyl chloride monomers to perform interfacial polymerization reaction at a two-phase interface for 30-60 s, and then placing the obtained composite nanofiltration membrane in an environment of 50-80 ℃ for heat treatment for 10-40 min to obtain the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity.
In some preferred embodiments, the surfactant includes sodium alkyl sulfate, preferably including any one or a combination of two or more of sodium octaalkyl sulfate, sodium dodecyl sulfate, sodium tetradecyl sulfate, but is not limited thereto; the nanowire includes nanofibers, preferably including any one or a combination of two or more of bacterial cellulose nanofibers, sulfonated cellulose nanofibers, single-walled carbon nanotubes, and multi-walled carbon nanotubes, but is not limited thereto. Wherein, the alkyl sodium sulfate and the nano-wires are dissolved in the aqueous solution to jointly regulate and control the diffusion process of the polyamine monomer.
The preparation principle of the composite nanofiltration membrane with ultrahigh lithium magnesium selectivity of the invention may be as follows: sodium alkyl sulfate added in a mixed aqueous solution containing polyamine monomer/sodium alkyl sulfate and nanowires, wherein the sodium alkyl sulfate and the polyamine monomer are gathered at an interface through electrostatic interaction, and the nanowires give the other one of the sodium alkyl sulfate and the nanowire weak electrostatic interaction to inhibit upward diffusion of the polyamine monomer; the porous ultrafiltration support bottom film is used as an aqueous phase-oil phase interface of aqueous solution of polyamine monomer/sodium alkyl sulfate and nano wire and organic solution of polybasic acyl chloride monomer, and the polyamine monomer/sodium alkyl sulfate and polybasic acyl chloride monomer in the aqueous phase solution are subjected to interfacial polymerization reaction on the surface of the film, so that a polyamide selective separation layer is formed, meanwhile, the nano wire can not be upwards diffused, but only plays a role of inhibiting the diffusion of the polyamine monomer through electrostatic effect, so that the interfacial polymerization reaction process is not influenced, and the ultrahigh lithium magnesium selective film composite nanofiltration film is obtained.
In some more specific embodiments, the method of preparation may specifically include:
adding the aqueous solution containing the polyamine monomer to the surface of the porous ultrafiltration support base membrane under the conditions of 50-70% of relative humidity and 20-30 ℃ of ambient temperature, and fully soaking for 10-150 s, preferably 60-90 s; and adding an aqueous solution containing a polyamine monomer, a surfactant such as sodium dodecyl sulfate and bacterial cellulose nanofiber and a nanowire to the surface of the porous ultrafiltration support base membrane, infiltrating the surface for 30-120 s, preferably 30-60 s, carrying out interfacial polymerization reaction on the polyamine monomer and the polybasic acyl chloride monomer at a two-phase interface for 30-60 s, wherein the sodium dodecyl sulfate provides a channel for the diffusion of the polyamine monomer from the aqueous phase to the organic phase, the bacterial cellulose nanofiber cannot diffuse upwards, only plays a role of inhibiting the diffusion of the polyamine through the electrostatic effect, and then placing the obtained composite nanofiltration membrane in an environment of 50-80 ℃ for heat treatment for 10-40 min to obtain the membrane composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity.
The types of the polyamine monomer and the polyacyl chloride monomer are all as described above, and are not described herein.
As one of the preferable schemes, the preparation method specifically comprises the following steps: and dissolving the polyamine monomer in water, and sequentially adding the surfactant and the nanowire to form the aqueous phase solution containing the polyamine monomer, the surfactant and the nanowire.
Further, the concentration of the surfactant in the aqueous phase solution is 0.6g/L to 2.4g/L, preferably 0.8g/L to 1.6g/L.
Further, the concentration of the nanowires in the aqueous solution is 0.01g/L to 0.2g/L, preferably 0.05g/L to 1.5g/L.
Further, the concentration of the polyamine monomer in the aqueous solution is 1g/L to 5g/L, preferably 2g/L to 4g/L.
In some embodiments, the method of making comprises: the aqueous solution containing the polyamine monomer, the surfactant and the nanowires (i.e. the mixed aqueous solution of polyamine/sodium dodecyl sulfate and bacterial cellulose nanofibers) is prepared by dissolving the polyamine monomer in an aqueous solution (i.e. a solution of sodium alkyl sulfate and nanowires).
Further, the aqueous solution comprises pure water, a polyamine monomer, sodium alkyl sulfate, and nanowires.
As one of the preferable schemes, the preparation method specifically comprises the following steps: and dissolving the polybasic acyl chloride monomer in an organic solvent to form the organic phase solution containing the polybasic acyl chloride monomer.
Further, the concentration of the polybasic acyl chloride monomer in the organic phase solution is 0.1g/L to 2g/L, preferably 0.5g/L to 1.5g/L.
Further, the organic solvent used for dissolving the polyacyl chloride monomer may be any one or a combination of two or more of n-hexane, benzene, toluene, cyclohexane, and the like, but is not limited thereto.
In some embodiments, the porous ultrafiltration support base membrane may be any one or a combination of two or more of a polyethersulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, a polysulfone ultrafiltration membrane, a sulfonated polysulfone ultrafiltration membrane, and a polyvinylidene chloride ultrafiltration membrane, and is preferably a polyethersulfone ultrafiltration membrane, but is not limited thereto.
Further, the pore diameter of the pores contained in the porous ultrafiltration support bottom membrane is 5-100 nm.
In some embodiments, the porous ultrafiltration support backing membrane is further provided with a nonwoven substrate, i.e., alternatively, the ultrafiltration porous support backing membrane may be nonwoven-backed or nonwoven-backed.
Wherein, as one of more specific embodiments, the preparation method specifically may include the following steps:
interfacial polymerization is carried out at the temperature of 20-30 ℃ and the relative humidity of 50-70 percent: the polyamine monomer is dissolved in pure water which is not mutually dissolved with the organic phase, the concentration is 2 g/L-4 g/L, the polyacyl chloride monomer is dissolved in sodium dodecyl sulfate solution with the concentration of 0.8 g/L-1.6 g/L and bacterial cellulose nanofiber solution with the concentration of 0.05 g/L-1.5 g/L, and the concentration is 0.5 g/L-1.5 g/L;
after removing residual water stains on the surface of the porous ultrafiltration support base film, dripping a mixed aqueous solution of polyamine monomer/sodium dodecyl sulfate and bacterial cellulose nanofiber on the surface of the porous ultrafiltration support base film, fully soaking the surface for 30-150 s, then sucking the residual aqueous solution on the surface to be dry until no visible water stains, then dripping an organic solution of polybasic acyl chloride monomer on the surface of the film to fully soak the surface of the film for 10-120 s, after interfacial polymerization reaction is carried out on the polyamine monomer and the polybasic acyl chloride monomer at a two-phase interface for 30-60 s, soaking the porous ultrafiltration base film in the organic solvent to wash out redundant unreacted acyl chloride monomer, then placing the film composite nanofiltration film in an environment of 50-80 ℃ for heat treatment for 10-40 min, and finally placing the film composite nanofiltration film into deionized water to be stored in a refrigerator, thus obtaining the ultrahigh lithium-magnesium selective film composite nanofiltration film.
In conclusion, the preparation method of the ultrahigh lithium magnesium selective membrane composite nanofiltration membrane provided by the invention is simple, and the ultrahigh separation selectivity and high retention of the nanofiltration membrane enable the energy consumption cost to be greatly reduced when the ultrahigh lithium magnesium selective membrane composite nanofiltration membrane is applied to aspects of multivalent/monovalent salt separation, brine extraction and the like, and the technology is easy to scale-up production and has high industrial application value.
Furthermore, the preparation method of the ultrahigh lithium-magnesium selective composite nanofiltration membrane is simpler, the cost of the used medicines and materials is low, the low pressure during operation ensures low energy consumption, and the ultrahigh lithium-magnesium selective composite nanofiltration membrane has higher flux and simultaneously has the advantages of high magnesium content and low cost of Mg 2+ Has ultrahigh interception efficiency and wide application prospect in the field of extracting lithium from brine.
Another aspect of embodiments of the present invention also provides a method for preparing a catalyst having both ultra-high separation selectivity and low Li + The trapped composite nanofiltration membrane with ultrahigh lithium magnesium selectivity.
Further, the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity of the invention has Mg in a mixed solution with a magnesium-lithium ratio of 21.4:1 2+ The retention rate of (2) is greater than 96%, preferably more than 98%; li (Li) + The retention rate of (2) is less than-90%, and is excellentThe separation factors of lithium and magnesium separation are more than 90 and preferably more than 100, the lithium and magnesium separation agent is selected below-100%, the lithium and magnesium separation agent has excellent separation and selection performance, and the pure water flux is up to 10Lm -2 h -1 The above.
Another aspect of the embodiment of the invention also provides an application of the composite nanofiltration membrane with ultrahigh lithium magnesium selectivity in the field of water treatment.
Further, the application comprises the application of the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity in the fields of multivalent/monovalent salt separation or brine extraction and the like.
Still further, the application includes: the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity is applied to lithium-magnesium separation.
Correspondingly, another aspect of the embodiment of the invention also provides a method for extracting lithium from brine, which comprises the following steps:
fully contacting brine with the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity to ensure that Li in the brine + 、Mg 2+ And separating to realize extraction of lithium in brine.
The technical solution of the present invention will be described in further detail below with reference to a number of preferred embodiments and accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. It should be noted that the examples described below are intended to facilitate the understanding of the present invention and are not intended to limit the present invention in any way. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. In the examples described below, the ultrafiltration membrane is exemplified by polyethersulfone ultrafiltration membrane, sulfonated polysulfone ultrafiltration membrane, and polyvinylidene chloride ultrafiltration membrane, sodium alkyl sulfate is exemplified by sodium octaalkyl sulfate, sodium dodecyl sulfate, and sodium dodecyl sulfate, the nanofibers are exemplified by bacterial cellulose nanofibers, sulfonated cellulose nanofibers, and single-walled carbon nanotubes, the polyamine monomer is exemplified by dendritic polyamidoamine and polyethyleneimine, the organic solvent is exemplified by n-hexane, and the polyacyl chloride monomer is exemplified by trimesoyl chloride; some simple modifications of the method according to the invention are intended to be within the scope of the claims.
Example 1
Dissolving dendritic Polyamidoamine (PAMAM) in a pure water solution to prepare a dendritic polyamidoamine water solution with the concentration of 2.8g/L, dissolving sodium dodecyl sulfate in the dendritic polyamidoamine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nano fibers in the water solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 100 seconds at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) is 98.3% and-90.2%, and the pure water flux is 14.86Lm -2 h -1 。
Example 2
Dissolving dendritic Polyamidoamine (PAMAM) in a pure water solution to prepare a dendritic polyamidoamine water solution with the concentration of 2.8g/L, dissolving sodium dodecyl sulfate in the dendritic polyamidoamine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nano fibers in the water solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 100 seconds at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of the catalyst was 98.0% and-98.2%, and the pure water flux was 14.32Lm -2 h -1 。
Example 3
Dissolving dendritic Polyamidoamine (PAMAM) in a pure water solution to prepare a dendritic polyamidoamine water solution with the concentration of 2.8g/L, dissolving sodium dodecyl sulfate in the dendritic polyamidoamine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing single-wall carbon nano tubes therein with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 100 seconds at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) is 98.0% and-100.2%, and the pure water flux is 14.67Lm -2 h -1 。
Example 4
Dissolving Polyethylenimine (PEI) in pure water solution to prepare an aqueous polyethylenimine solution with the concentration of 2.8g/L, dissolving sodium dodecyl sulfate in the aqueous polyethylenimine solution to prepare an aqueous solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nanofibers in the aqueous solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 100 seconds at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of the catalyst was 98.9% and-93.5%, and the pure water flux was 14.24Lm -2 h -1 。
Example 5
Dissolving dendritic Polyamidoamine (PAMAM) in a pure water solution to prepare a dendritic polyamidoamine water solution with the concentration of 2.8g/L, dissolving sodium dodecyl sulfate in the dendritic polyamidoamine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nano fibers in the water solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 100 seconds at the temperature of 27 ℃ and the relative humidity of 70%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) is 98.5% and-94.3%, and the pure water flux is 14.91Lm -2 h -1 。
Example 6
Dissolving Polyethylenimine (PEI) in pure water solution to prepare an aqueous polyethylenimine solution with the concentration of 2.8g/L, dissolving sodium dodecyl sulfate in the aqueous polyethylenimine solution to prepare an aqueous solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nanofibers in the aqueous solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. After the polyvinylidene chloride ultrafiltration bottom membrane is soaked on the surface for 100 seconds with the aqueous solution at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked with the acyl chloride solution with the concentration of 1g/L for reaction for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of the catalyst was 98.2% and-93.0%, and the pure water flux was 13.03Lm -2 h -1 。
Example 7
Dissolving Polyethyleneimine (PEI) in a pure water solution to prepare a polyethyleneimine water solution with the concentration of 5g/L, dissolving sodium dodecyl sulfate in the polyethyleneimine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nano fibers in the water solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. After the polyvinylidene chloride ultrafiltration bottom membrane is soaked on the surface for 60 seconds with the aqueous solution at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked with the acyl chloride solution with the concentration of 1g/L for reaction for 60 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 30min at 60 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment uses magnesium respectively under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2barMixed salt with lithium ratio of 21.4:1 was tested, mg 2+ And Li (lithium) + The retention rate of (C) was 98.9% and-94.2%, and the pure water flux was 13.59Lm -2 h -1 。
Example 8
Dissolving Polyethyleneimine (PEI) in a pure water solution to prepare a polyethyleneimine water solution with the concentration of 5g/L, dissolving sodium dodecyl sulfate in the polyethyleneimine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nano fibers in the water solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. After the polyvinylidene chloride ultrafiltration bottom membrane is soaked on the surface for 60 seconds with the aqueous solution at the temperature of 27 ℃ and the relative humidity of 70%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked with the acyl chloride solution with the concentration of 1g/L for reaction for 60 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 30min at 60 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) was 98.3% and-83.9%, and the pure water flux was 13.61Lm -2 h -1 。
Example 9
Dissolving Polyethyleneimine (PEI) in a pure water solution to prepare a polyethyleneimine water solution with the concentration of 5g/L, dissolving sodium octaalkyl sulfate in the polyethyleneimine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nano fibers in the water solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. After the polyvinylidene chloride ultrafiltration bottom membrane is soaked on the surface for 100 seconds with the aqueous solution at the temperature of 27 ℃ and the relative humidity of 70%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked with the acyl chloride solution with the concentration of 1g/L for reaction for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) was 98.8% and-83.9%, and the pure water flux was 13.92Lm -2 h -1 。
Example 10
Dissolving dendritic Polyamidoamine (PAMAM) in a pure water solution to prepare a dendritic polyamidoamine water solution with the concentration of 2.8g/L, dissolving sodium dodecyl sulfate in the dendritic polyamidoamine water solution to prepare a water solution with the concentration of 1.0g/L, and dispersing bacterial cellulose nano fibers in the water solution with the concentration of 0.2g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 60 seconds at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for reaction for 60 seconds, and then the membrane is soaked in n-hexane for 60 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 30min at 60 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of the catalyst was 98.3% and-101%, and the pure water flux was 15.02Lm -2 h -1 。
According to tests, in the embodiment, MWCO and pore size distribution diagrams of the surface of the membrane after interfacial polymerization with sodium dodecyl sulfate and bacterial cellulose nanofibers added and without added are shown in fig. 1 and 2 respectively, and as can be seen from fig. 1 and 2, the interfacial polymerization reaction is carried out after the sodium dodecyl sulfate and the bacterial cellulose nanofibers are added, the pore size distribution of the nanofiltration membrane is basically unchanged, and the molecular weight cut-off is slightly increased. Fig. 3 is an SEM image of the surface morphology of the membrane composite nanofiltration after adding sodium dodecyl sulfate and bacterial cellulose nanofibers.
Example 11
Dissolving dendritic Polyamidoamine (PAMAM) in pure water solution to prepare dendritic polyamidoamine water solution with the concentration of 5g/L, dissolving sodium octaalkyl sulfate with the dendritic polyamidoamine water solution to prepare 1.6g/L water solution, and dispersing bacterial cellulose nano fibers with the concentration of 0.01g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1.5 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 60 seconds at the temperature of 25 ℃ and the relative humidity of 60%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1.5g/L for reaction for 60 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 30min at 60 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) is 98.0% and-96.4%, and the pure water flux is 14.32Lm -2 h -1 。
Example 12
Dissolving dendritic Polyamidoamine (PAMAM) in pure water solution to prepare dendritic polyamidoamine water solution with the concentration of 5g/L, dissolving sodium octaalkyl sulfate with the dendritic polyamidoamine water solution to prepare 1.0g/L water solution, and dispersing sulfonated cellulose nanofibers with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 150 seconds at the temperature of 20 ℃ and the relative humidity of 50%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for 120 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 10min at 80 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) was 97.2% and-86.3%, and the pure water flux was 16.10Lm -2 h -1 。
Example 13
Dissolving dendritic Polyamidoamine (PAMAM) in pure water solution to prepare dendritic polyamidoamine water solution with the concentration of 5g/L, dissolving sodium octaalkyl sulfate with the dendritic polyamidoamine water solution to prepare water solution with the concentration of 0.6g/L, and dispersing single-wall carbon nano tubes therein with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 120 seconds at the temperature of 27 ℃ and the relative humidity of 70%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 1g/L for reaction for 60 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 40min at 50 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) was 97.9% and-96.1%, and the pure water flux was 12.49Lm -2 h -1 。
Example 14
Dissolving dendritic Polyamidoamine (PAMAM) in a pure water solution to prepare a dendritic polyamidoamine water solution with the concentration of 1g/L, dissolving sodium octaalkyl sulfate in the dendritic polyamidoamine water solution to prepare a water solution with the concentration of 2.4g/L, and dispersing sulfonated cellulose nanofibers in the water solution with the concentration of 0.1g/L; the trimesoyl chloride monomer is dissolved in normal hexane to prepare acyl chloride solution with the concentration of 0.1 g/L. The surface of the sulfonated polysulfone ultrafiltration bottom membrane is soaked in the aqueous solution for 10 seconds at the temperature of 30 ℃ and the relative humidity of 70%, the solution on the surface of the membrane is sucked to be dry until no visible water stain exists, then the surface of the membrane is soaked in the acyl chloride solution with the concentration of 0.1g/L for 30 seconds, and then the membrane is soaked in n-hexane for 30 seconds to wash out residual trimesoyl chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 10min at 80 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested by mixed salt with magnesium-lithium ratio of 21.4:1 and Mg under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar 2+ And Li (lithium) + The retention rate of (C) was 96.2% and-76.5%, and the pure water flux was 16.30Lm -2 h -1 。
It should be noted that: the ultrahigh lithium magnesium selectivity composite nanofiltration membranes obtained in the above examples were tested by cross-flow mode. The retention rate of salt is calculated according to the ratio of the concentration of permeate to the concentration of feed liquid, and the calculation formula is as follows:
pure water flux is based on the volume of liquid filtered per hour per square meter of membrane area and normalized to unit atmospheric pressure:
comparative example 1
The polyether sulfone ultrafiltration membrane is used as a support base membrane, and dendritic polyamide (2.8 g/L) and trimesoyl chloride (1 g/L) are respectively used as polyamine monomers and polybasic acyl chloride monomers on the surface of the support base membrane for interfacial polymerization reaction to obtain the polyamide film composite nanofiltration membrane. However, the traditional nanofiltration membrane has low flux and low retention rate, and the separation factor of lithium and magnesium is low, so that the separation effect of lithium and magnesium is far from being achieved.
Through testing, the film composite nanofiltration membrane prepared in the comparative example is tested in mixed salt with the magnesium-lithium ratio of 21.4:1 under the conditions that the testing temperature is 25 ℃ and the operating pressure is 2bar, and Mg 2+ And Li (lithium) + The retention rate of (C) is 36% and-15.8%, and the pure water flux is 18Lm -2 h -1 . And the membrane has large pore diameter, wide pore diameter distribution and large molecular weight cut-off.
Control example 2 (aqueous phase surfactant: SDS, sodium dodecyl sulfate)
Preparing a solution with the concentration of 1CMC by using deionized water for sodium dodecyl sulfate molecules, and then dissolving dendritic Polyamidoamine (PAMAM) monomers by using the sodium dodecyl sulfate solution to prepare a dendritic polyamidoamine/sodium dodecyl sulfate solution with the concentration of 2.8 g/L; the trimesoyl chloride (TMC) monomer was dissolved with de-n-hexane to prepare an acid chloride solution at a concentration of 1 g/L. At the temperature of 25 ℃ and relative humidity of 60%, the polyethersulfone ultrafiltration bottom membrane is soaked with 2.8g/L dendritic polyamidoamine/sodium dodecyl sulfate solution for 1min, the surface solution of the membrane is sucked to be free of visible water stains, then the surface of the membrane is soaked with 1g/L trimesic acid chloride/dibutyl phosphate solution for 30s, and then the membrane is soaked in n-hexane for 30s to wash out residual trimesic acid chloride monomer on the surface. Finally, the film is put into an oven, and is soaked in deionized water and stored in a refrigerator after being heat treated for 30min at 60 ℃.
Through testing, the ultrahigh lithium-magnesium selective film composite nanofiltration membrane prepared in the embodiment is tested in mixed salt with a magnesium-lithium ratio of 21.4:1 at a testing temperature of 25 ℃ and an operating pressure of 2bar, and Mg 2+ And Li (lithium) + The retention rate of (2) was 98% and 10%, and the pure water flux was 10Lm -2 h -1 . In lithium magnesium separation, lithium is lost, and lithium is not suitable for enrichment.
In addition, the present inventors have also conducted experiments with other raw materials, conditions, etc. listed in the present specification in the manner of example 1-example 14, and have also produced ultra-high lithium magnesium selective membrane composite nanofiltration membranes having both ultra-high separation factor for lithium magnesium and low lithium rejection.
The various aspects, embodiments, features and examples of the invention are to be considered in all respects as illustrative and not intended to limit the invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.
While the invention has been described with reference to an illustrative embodiment, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (23)
1. The preparation method of the composite nanofiltration membrane with ultrahigh lithium magnesium selectivity is characterized by comprising the following steps of:
providing a porous ultrafiltration support membrane;
contacting an aqueous phase solution containing polyamine monomers, a surfactant and a nanowire with the surface of the porous ultrafiltration support base membrane under the conditions of 50-70% of relative humidity and 20-30 ℃ of ambient temperature, fully soaking for 10-150 s, adding an organic phase solution containing polybasic acyl chloride monomers to the surface of the porous ultrafiltration support base membrane, soaking for 30-120 s, wherein the polyamine monomers and the surfactant molecules are gathered at an interface through a first electrostatic interaction force, the nanowire gives a second electrostatic interaction force and limits the upward diffusion of the polyamine monomers, so that the polyamine monomers and the polybasic acyl chloride monomers perform interfacial polymerization reaction at a two-phase interface for 30-60 s, thereby forming a compact polyamide separation selection layer on the surface of the porous ultrafiltration support base membrane, and then placing the obtained composite nanofiltration membrane in the environment of 50-80 ℃ for heat treatment for 10-40 min to obtain the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity;
wherein the surfactant is selected from any one or more than two of sodium octaalkyl sulfate, sodium dodecyl sulfate and sodium tetradecyl sulfate; the nanowire is selected from any one or the combination of more than two of bacterial cellulose nanofiber, sulfonated cellulose nanofiber, single-wall carbon nanotube and multi-wall carbon nanotube; the concentration of the surfactant in the aqueous phase solution is 0.6-g/L-2.4 g/L, the concentration of the nanowire in the aqueous phase solution is 0.01-g/L-0.2 g/L, the concentration of the polyamine monomer in the aqueous phase solution is 1-g/L-5 g/L, and the concentration of the polyacyl chloride monomer in the organic phase solution is 0.1-g/L-2 g/L;
The composite nanofiltration membrane with the ultrahigh lithium magnesium selectivity comprises a porous ultrafiltration support bottom membrane and a polyamide selective separation layer arranged on the porous ultrafiltration support bottom membrane, wherein the thickness of the polyamide selective separation layer is 20-60 nm;
the polyamide separation selection layer pair Mg 2+ The retention rate of ions is greater than 96%; for Li + The retention rate of ions is less than 30 percent; the flux of the composite nanofiltration membrane to pure water is 10 Lm -2 h -1 The above.
2. The preparation method according to claim 1, characterized in that it comprises in particular:
and (3) under the conditions that the relative humidity is 50-70% and the ambient temperature is 20-30 ℃, enabling an aqueous phase solution containing polyamine monomers, surfactants and nanowires to be in contact with the surface of the porous ultrafiltration support base membrane, fully soaking for 60-90 s, adding an organic phase solution containing polybasic acyl chloride monomers to the surface of the porous ultrafiltration support base membrane, soaking the surface for 30-60 s, and enabling the polyamine monomers and the polybasic acyl chloride monomers to carry out interfacial polymerization reaction at a two-phase interface.
3. The preparation method according to claim 1 or 2, characterized by comprising: and dissolving the polyamine monomer in water, and sequentially adding the surfactant and the nanowire to form the aqueous phase solution containing the polyamine monomer, the surfactant and the nanowire.
4. The method of manufacturing according to claim 1, characterized in that: the concentration of the surfactant in the aqueous phase solution is 0.8-g/L to 1.6-g/L.
5. The method of manufacturing according to claim 1, characterized in that: the concentration of the nanowires in the aqueous phase solution is 0.05 g/L-1.5 g/L.
6. The method of manufacturing according to claim 1, characterized in that: the concentration of the polyamine monomer in the aqueous phase solution is 2 g/L-4 g/L.
7. The method of manufacturing according to claim 1, characterized in that: the polyamine monomer is selected from any one or more than two of piperazine, polyethyleneimine, m-phenylenediamine and dendritic polyamidoamine.
8. The preparation method according to claim 1 or 2, characterized by comprising: and dissolving the polybasic acyl chloride monomer in an organic solvent to form the organic phase solution containing the polybasic acyl chloride monomer.
9. The method of manufacturing according to claim 8, wherein: the concentration of the polybasic acyl chloride monomer in the organic phase solution is 0.5-g/L to 1.5-g/L.
10. The method of manufacturing according to claim 8, wherein: the polybasic acyl chloride monomer is selected from any one or more than two of trimesoyl chloride, isophthaloyl dichloride, adipoyl chloride and terephthaloyl dichloride.
11. The method of manufacturing according to claim 8, wherein: the organic solvent is selected from any one or more than two of n-hexane, benzene, toluene and cyclohexane.
12. The method of manufacturing according to claim 1, characterized in that: the porous ultrafiltration support bottom membrane is made of a polyether sulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, a polysulfone ultrafiltration membrane, a sulfonated polysulfone ultrafiltration membrane or a polyvinylidene chloride ultrafiltration membrane.
13. The method of manufacturing according to claim 12, wherein: the porous ultrafiltration support bottom membrane is made of a polyethersulfone ultrafiltration membrane.
14. The method of manufacturing according to claim 1, characterized in that: the pore diameter of the pores contained in the porous ultrafiltration support bottom membrane is 5-100 nm.
15. The method of manufacturing according to claim 1, characterized in that: the porous ultrafiltration support bottom membrane is also provided with a non-woven fabric substrate.
16. The method of manufacturing according to claim 1, characterized in that: the polyamide separation selection layer pair Mg 2+ The rejection rate of ions is above 98%; for Li + The retention rate of ions is below 28%.
17. The method of manufacturing according to claim 1, characterized in that: at a magnesium to lithium ratio of 21.4:1 in the mixed solution of Mg 2 + The retention rate of the polymer is greater than 96%; li (Li) + The retention rate of the lithium-magnesium composite material is less than-90%, and the separation factors of lithium-magnesium separation are more than 90.
18. The method of manufacturing according to claim 17, wherein: at a magnesium to lithium ratio of 21.4:1 in the mixed solution of Mg 2+ The retention rate of the catalyst is above 98%; li (Li) + The retention rate of the lithium-magnesium alloy is below-100%, and the separation factor of lithium-magnesium separation is above 100.
19. The method of manufacturing according to claim 1, characterized in that: the flux of the composite nanofiltration membrane to pure water is 15 Lm -2 h -1 The above.
20. The method of manufacturing according to claim 1, characterized in that: the aperture of the holes contained in the polyamide selective separation layer of the composite nanofiltration membrane is more than 0.550 and nm, and the molecular weight cut-off is more than 160 and Da.
21. The method of manufacturing according to claim 20, wherein: the aperture of the holes contained in the polyamide selective separation layer of the composite nanofiltration membrane is 0.550-0.560 nm, and the molecular weight cut-off is 180-200 Da.
22. Use of a composite nanofiltration membrane with ultra-high lithium-magnesium selectivity produced by the production process of any one of claims 1-21 in the field of lithium-magnesium separation or brine extraction.
23. A method for extracting lithium from brine, comprising:
Contacting brine with the composite nanofiltration membrane with ultrahigh lithium-magnesium selectivity prepared by the preparation method of any one of claims 1-21 sufficiently to allow Li therein to be contained + 、Mg 2+ And separating to realize extraction of lithium in brine.
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