CN114191992A - Composite nanofiltration membrane for extracting lithium from salt lake and preparation method thereof - Google Patents
Composite nanofiltration membrane for extracting lithium from salt lake and preparation method thereof Download PDFInfo
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- CN114191992A CN114191992A CN202111578632.2A CN202111578632A CN114191992A CN 114191992 A CN114191992 A CN 114191992A CN 202111578632 A CN202111578632 A CN 202111578632A CN 114191992 A CN114191992 A CN 114191992A
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- nanofiltration membrane
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- salt lake
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- 239000012528 membrane Substances 0.000 title claims abstract description 116
- 238000001728 nano-filtration Methods 0.000 title claims abstract description 85
- 239000002131 composite material Substances 0.000 title claims abstract description 71
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title claims abstract description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000002791 soaking Methods 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 239000007788 liquid Substances 0.000 claims abstract description 3
- 239000000243 solution Substances 0.000 claims description 59
- 239000012071 phase Substances 0.000 claims description 42
- 239000003054 catalyst Substances 0.000 claims description 21
- 239000002904 solvent Substances 0.000 claims description 19
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 17
- VHYFNPMBLIVWCW-UHFFFAOYSA-N 4-Dimethylaminopyridine Chemical compound CN(C)C1=CC=NC=C1 VHYFNPMBLIVWCW-UHFFFAOYSA-N 0.000 claims description 16
- 229920002873 Polyethylenimine Polymers 0.000 claims description 14
- 238000000605 extraction Methods 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 12
- 238000012986 modification Methods 0.000 claims description 12
- 239000000654 additive Substances 0.000 claims description 11
- 230000004048 modification Effects 0.000 claims description 11
- 150000001263 acyl chlorides Chemical class 0.000 claims description 10
- 230000000996 additive effect Effects 0.000 claims description 10
- 239000008346 aqueous phase Substances 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 9
- 150000001412 amines Chemical class 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 9
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims description 8
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical compound NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 claims description 8
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 6
- 238000005266 casting Methods 0.000 claims description 5
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 claims description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 4
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- 239000004695 Polyether sulfone Substances 0.000 claims description 4
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 4
- UWCPYKQBIPYOLX-UHFFFAOYSA-N benzene-1,3,5-tricarbonyl chloride Chemical compound ClC(=O)C1=CC(C(Cl)=O)=CC(C(Cl)=O)=C1 UWCPYKQBIPYOLX-UHFFFAOYSA-N 0.000 claims description 4
- 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 4
- 229940018564 m-phenylenediamine Drugs 0.000 claims description 4
- 229920006393 polyether sulfone Polymers 0.000 claims description 4
- LXEJRKJRKIFVNY-UHFFFAOYSA-N terephthaloyl chloride Chemical compound ClC(=O)C1=CC=C(C(Cl)=O)C=C1 LXEJRKJRKIFVNY-UHFFFAOYSA-N 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 3
- 238000000576 coating method Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 239000004745 nonwoven fabric Substances 0.000 claims description 3
- 229940068918 polyethylene glycol 400 Drugs 0.000 claims description 3
- 239000011347 resin Substances 0.000 claims description 3
- 229920005989 resin Polymers 0.000 claims description 3
- 238000007790 scraping Methods 0.000 claims description 3
- 238000009849 vacuum degassing Methods 0.000 claims description 3
- 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
- FYXKZNLBZKRYSS-UHFFFAOYSA-N benzene-1,2-dicarbonyl chloride Chemical compound ClC(=O)C1=CC=CC=C1C(Cl)=O FYXKZNLBZKRYSS-UHFFFAOYSA-N 0.000 claims description 2
- VKIRRGRTJUUZHS-UHFFFAOYSA-N cyclohexane-1,4-diamine Chemical compound NC1CCC(N)CC1 VKIRRGRTJUUZHS-UHFFFAOYSA-N 0.000 claims description 2
- HXTYZWJVMWWWDK-UHFFFAOYSA-N cyclohexane-1,4-dicarbonyl chloride Chemical compound ClC(=O)C1CCC(C(Cl)=O)CC1 HXTYZWJVMWWWDK-UHFFFAOYSA-N 0.000 claims description 2
- YVOFTMXWTWHRBH-UHFFFAOYSA-N pentanedioyl dichloride Chemical compound ClC(=O)CCCC(Cl)=O YVOFTMXWTWHRBH-UHFFFAOYSA-N 0.000 claims description 2
- 229940113115 polyethylene glycol 200 Drugs 0.000 claims description 2
- 229940068886 polyethylene glycol 300 Drugs 0.000 claims description 2
- 229940085675 polyethylene glycol 800 Drugs 0.000 claims description 2
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- 238000005303 weighing Methods 0.000 claims description 2
- JDTUPLBMGDDPJS-UHFFFAOYSA-N 2-methoxy-2-phenylethanol Chemical compound COC(CO)C1=CC=CC=C1 JDTUPLBMGDDPJS-UHFFFAOYSA-N 0.000 claims 1
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 abstract description 13
- 238000000926 separation method Methods 0.000 abstract description 13
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 abstract description 10
- GCICAPWZNUIIDV-UHFFFAOYSA-N lithium magnesium Chemical compound [Li].[Mg] GCICAPWZNUIIDV-UHFFFAOYSA-N 0.000 abstract description 9
- 229910001629 magnesium chloride Inorganic materials 0.000 abstract description 7
- 230000004907 flux Effects 0.000 abstract description 6
- 238000002834 transmittance Methods 0.000 abstract description 4
- 230000014759 maintenance of location Effects 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 description 26
- 230000000694 effects Effects 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- 239000012267 brine Substances 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 230000035699 permeability Effects 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 3
- 229920000604 Polyethylene Glycol 200 Polymers 0.000 description 3
- 229920002593 Polyethylene Glycol 800 Polymers 0.000 description 3
- 239000008364 bulk solution Substances 0.000 description 3
- 238000010889 donnan-equilibrium Methods 0.000 description 3
- 229910001425 magnesium ion Inorganic materials 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 229920002565 Polyethylene Glycol 400 Polymers 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- JLFNLZLINWHATN-UHFFFAOYSA-N pentaethylene glycol Chemical compound OCCOCCOCCOCCOCCO JLFNLZLINWHATN-UHFFFAOYSA-N 0.000 description 2
- 150000003335 secondary amines Chemical class 0.000 description 2
- 238000012695 Interfacial polymerization Methods 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- CNLWCVNCHLKFHK-UHFFFAOYSA-N aluminum;lithium;dioxido(oxo)silane Chemical compound [Li+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O CNLWCVNCHLKFHK-UHFFFAOYSA-N 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- IRXBNHGNHKNOJI-UHFFFAOYSA-N butanedioyl dichloride Chemical compound ClC(=O)CCC(Cl)=O IRXBNHGNHKNOJI-UHFFFAOYSA-N 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000003631 expected effect Effects 0.000 description 1
- KWLMIXQRALPRBC-UHFFFAOYSA-L hectorite Chemical compound [Li+].[OH-].[OH-].[Na+].[Mg+2].O1[Si]2([O-])O[Si]1([O-])O[Si]([O-])(O1)O[Si]1([O-])O2 KWLMIXQRALPRBC-UHFFFAOYSA-L 0.000 description 1
- 229910000271 hectorite Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 229910052629 lepidolite Inorganic materials 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- VAOCPAMSLUNLGC-UHFFFAOYSA-N metronidazole Chemical compound CC1=NC=C([N+]([O-])=O)N1CCO VAOCPAMSLUNLGC-UHFFFAOYSA-N 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910052642 spodumene Inorganic materials 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
Classifications
-
- 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
- B01D67/0088—Physical treatment with compounds, e.g. swelling, coating or impregnation
-
- 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
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0093—Chemical modification
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/16—Membrane materials having positively charged functional groups
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Nanotechnology (AREA)
- Water Supply & Treatment (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention provides a composite nanofiltration membrane for extracting lithium from a salt lake and a preparation method thereof, belonging to the technical field of nanofiltration membrane preparation. Soaking a basic membrane in a water phase solution and an oil phase solution in sequence, and performing heat treatment to obtain a nascent state composite nanofiltration membrane; and then modifying by adopting post-treatment liquid to obtain the nanofiltration membrane with positive charges on the surface. The composite nanofiltration membrane has high water flux, and has the characteristics of high magnesium chloride retention rate and high lithium chloride transmittance. The composite nanofiltration membrane can improve the magnesium-lithium separation ratio and improve the separation efficiency.
Description
Technical Field
The invention relates to the technical field of nanofiltration membrane preparation, in particular to a composite nanofiltration membrane for lithium extraction in a salt lake and a preparation method thereof.
Background
Lithium is a type of lithium ion in salt lake brine, underground brine and seawater in nature, and exists mainly in the form of solid hectorite in pegmatite such as spodumene and lepidolite. At present, lithium extraction from salt lake brine is a main source of global lithium salt production, and a nanofiltration technology becomes a novel extraction technology aiming at the exploitation of salt lakes with high magnesium-lithium ratio.
Nanofiltration membranes, which are a new type of pressure-driven membrane between RO and UF membranes, are being gradually explored and clarified to be suitable for their own application boundaries. Nanofiltration membranes are used as a novel membrane separation technology, and the separation effect is mainly determined by the pore size, the charge effect and the dielectric effect. Therefore, the salt separating agent has selective permeability to different ions, thereby realizing the salt separating effect. The charge effect is also known as the Donnan effect and when a charged group membrane is placed in a solvent containing salts, the concentration of the counter ion (the ion with a charge opposite to the fixed charge in the membrane) in the solution is greater than that in the bulk solution, while the concentration of the ion of the same name in the membrane is lower than that in the bulk solution. The Donnan potential difference thus formed prevents diffusion of the homonymous ions from the bulk solution into the membrane, and the counterions are also trapped by the membrane in order to maintain electroneutrality.
However, the nanofiltration membranes currently used in the market are generally electronegative nanofiltration membranes, and are influenced by the Donnan effect as a main factor, and can effectively separate monovalent, divalent and higher anions, but have poor effects on separating monovalent, divalent and higher cations. Therefore, the nanofiltration membrane in the market cannot efficiently separate magnesium ions and lithium ions in salt lake brine.
In conclusion, a nanofiltration membrane with electropositive surface charge and a preparation method thereof are urgently needed to solve the problems in the prior art, namely, the nanofiltration membrane with low lithium chloride rejection rate and high magnesium chloride rejection rate is produced and is applied to the separation of magnesium and lithium in salt lake brine.
Disclosure of Invention
In view of the above, the invention provides a composite nanofiltration membrane for lithium extraction from a salt lake and a preparation method thereof, the composite nanofiltration membrane has high water flux, and not only can increase the retention rate of magnesium chloride, but also can improve the transmittance of lithium chloride.
The invention aims to provide a preparation method of a composite nanofiltration membrane for extracting lithium from a salt lake, which comprises the following steps:
(1) preparing an aqueous phase solution: uniformly mixing an amine substance, a water-phase additive and deionized water to obtain a water-phase solution;
(2) preparing an oil phase solution: uniformly mixing polybasic acyl chloride and an oil phase solvent to obtain an oil phase solution;
(3) preparing a nascent state composite nanofiltration membrane: firstly, soaking a base film in an aqueous phase solution, and then soaking the base film in an oil phase solution; carrying out heat treatment on the basic membrane soaked by the oil phase solution to obtain a nascent state composite nanofiltration membrane;
(4) preparation of the post-treatment solution: mixing polyethyleneimine, a catalyst and an alcohol solvent to prepare a post-treatment solution;
(5) post-treatment modification: and (4) immersing the nascent-state composite nanofiltration membrane obtained in the step (3) into the post-treatment solution, and obtaining the composite nanofiltration membrane for extracting lithium from the salt lake after the post-treatment modification is completed.
Preferably, the amine substance in the step (1) is at least one of piperazine, 1, 6-hexamethylene diamine, 1, 4-diaminocyclohexane and m-phenylenediamine;
the water phase additive is at least one of polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400 and polyethylene glycol 800;
the mass ratio of the amine substances, the water-phase additive and the deionized water in the water-phase solution is 0.5-3: 1-5: 92-98.5.
Preferably, the polybasic acyl chloride in the step (2) is at least one of trimesoyl chloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, 4' -biphenyldicarbonyl chloride, succinoyl chloride, glutaryl dichloride, adipoyl chloride and 1, 4-cyclohexanedicarboxylic chloride;
the oil phase solvent is at least one of n-hexane, cyclohexane and heptane;
the mass ratio of the polybasic acyl chloride to the oil phase solvent in the oil phase solution is 0.05-1: 99 to 99.95.
Preferably, the preparation method of the base film in the step (3) is as follows:
weighing polyether sulfone resin and N-methyl pyrrolidone, mixing to prepare a solution, heating and stirring for 6 hours to prepare a uniformly dispersed casting film liquid, filtering, vacuum degassing, uniformly coating on a non-woven fabric on a film scraping machine, wherein the wet film thickness is 150-170 mu m, curing to form a film to obtain the base film, and refrigerating the base film in a freezer at 5 ℃ for later use.
Preferably, the nascent composite nanofiltration membrane in the step (3) is soaked in the aqueous phase solution for 15-25 s, and then a rubber roller is adopted to remove the residual aqueous phase solution on the surface of the basic membrane; soaking the base film in the oil phase solution for 10-20 s, and then removing the residual oil phase solution on the surface of the base film by using a rubber roller.
Preferably, the heat treatment method in the step (3) is to place the base film soaked in the oil phase solution in an oven at 30-90 ℃ for 1-30 min.
Preferably, the molecular weight of the polyethyleneimine of step (4) is 600, 1800, 10000 or 20000;
the catalyst is at least one of 4-dimethylamino pyridine, triethylamine and pyridine;
the alcohol solvent is at least one of methanol, ethanol and isopropanol;
preferably, the mass ratio of the polyethyleneimine, the catalyst and the alcohol solvent in the post-treatment solution in the step (4) is 0.5-3: 0.1-0.5: 96.5 to 99.4.
Preferably, the soaking time of the nascent-state composite nanofiltration membrane in the step (4) in the post-treatment modified solution is 1-20 min.
The invention also aims to provide the composite nanofiltration membrane for extracting lithium from the salt lake, which is prepared by the method.
The invention provides a preparation method of a composite nanofiltration membrane for lithium extraction in a salt lake.
Compared with the prior art, the invention has the following beneficial effects:
(1) in the preparation process of the nascent-state composite nanofiltration membrane prepared by the invention, a large amount of unreacted-NH exists on the membrane2reacting-COCl, then carrying out post-treatment modification on the nascent composite nanofiltration membrane, adding a catalyst in the post-treatment process to improve the reaction rate of secondary amine and-COCl in polyethyleneimine, further reacting unreacted-COCl in a molecular chain with secondary amine in the polyethyleneimine, reducing the content of-COCl hydrolyzed to-COOH at the tail end of a polyamide molecular chain, and simultaneously increasing a large amount of-NH-A group. The membrane surface which is originally electronegative is converted into electropositive, and the pore diameter of the membrane is not greatly changed. The main factor of the lithium ion rejection rate is the pore size, so the lithium ion rejection rate is basically unchanged; the main influencing factor of magnesium ion rejection is the Donnan effect, because the electropositive membrane surface greatly improves the rejection of magnesium ions.
(2) According to the invention, polyethylene glycol is used as a water phase additive, the viscosity of the solution is adjusted, the interfacial polymerization rate is delayed, the water production flux of the nanofiltration membrane is improved, and the permeability of inorganic salt is not influenced, so that the retention rate of magnesium chloride is increased, the permeability of lithium chloride is increased, and the magnesium-lithium separation coefficient of lithium extracted from a salt lake is further improved.
(3) The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake is simple, short in process flow, low in cost and good in application prospect.
Detailed Description
The present invention is further illustrated by the following examples, in which the preferred embodiments and materials are shown for illustrative purposes only.
Example 1
A preparation method of a composite nanofiltration membrane for extracting lithium from a salt lake comprises the following steps:
(1) preparing an aqueous phase solution: uniformly mixing piperazine, polyethylene glycol 400 and deionized water according to the mass ratio of 1:3:96 to obtain an aqueous phase solution;
(2) preparing an oil phase solution: uniformly mixing trimesoyl chloride and n-hexane according to the mass ratio of 0.2:99.8 to obtain an oil phase solution;
(3) preparing a nascent state composite nanofiltration membrane: soaking the base membrane in the aqueous phase solution for 20s, removing the aqueous phase solution remained on the surface of the base membrane by using a rubber roller, soaking the base membrane in the oil phase solution for 15s, removing the oil phase solution remained on the surface of the base membrane by using the rubber roller, placing the base membrane soaked in the oil phase solution in a drying oven at 70 ℃, and carrying out heat treatment for 5min to obtain the nascent state composite nanofiltration membrane;
(4) preparation of the post-treatment solution: mixing polyethyleneimine with polymerization degree of 10000, triethylamine and methanol solvent according to a mass ratio of 1:0.3:98.7 mixing to prepare a post-treatment solution;
(5) post-treatment modification: and (4) immersing the nascent-state composite nanofiltration membrane obtained in the step (3) into the post-treatment solution for soaking for 15min, and obtaining the composite nanofiltration membrane for extracting lithium from the salt lake after post-treatment modification is completed.
The preparation method of the base film comprises the following steps:
75g of polyether sulfone resin (PES) and 425g of N-methylpyrrolidone (NMP) are weighed and mixed to prepare 500g of solution, and the solution is stirred for 6 hours at 70 ℃ to prepare uniformly dispersed membrane casting solution. Filtering and vacuum degassing the membrane casting solution, uniformly coating the membrane casting solution on a non-woven fabric on a membrane scraping machine, wherein the wet membrane thickness is 150 mu m, evaporating for 3s at room temperature, and then immersing in ultrapure water at 16 ℃ for gel curing to form a membrane. Then, the film was completely cured with water at normal temperature, and finally the film was washed in water at 75 ℃ for 3min to obtain a base film, and the base film was refrigerated in a freezer at 5 ℃ for use.
Example 2
The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake comprises the same steps as in example 1, wherein the amine substance in the raw material is 1, 6-hexamethylene diamine, and the other raw materials are the same as in example 1.
Example 3
The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake comprises the same steps as the example 1, wherein the amine substance in the raw material is m-phenylenediamine, and other raw materials are the same as the example 1.
Example 4
The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake comprises the same steps as the example 1, wherein the polybasic acyl chloride in the raw material is isophthaloyl dichloride, and other raw materials are the same as the example 1.
Example 5
The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake comprises the same steps as the example 1, wherein the polybasic acyl chloride substances in the raw materials are terephthaloyl chloride, and other raw materials are the same as the example 1.
Example 6
The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake comprises the same steps as the example 1, wherein the water-phase additive in the raw materials is PEG200, and other raw materials are the same as the example 1.
Example 7
The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake comprises the same steps as the example 1, wherein the water phase additive in the raw materials is PEG800, and other raw materials are the same as the example 1.
Example 8
The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake comprises the same steps as the example 1, wherein the catalyst in the raw material is 4-dimethylaminopyridine, and other raw materials are the same as the example 1.
Example 9
The preparation method of the composite nanofiltration membrane for lithium extraction in the salt lake comprises the same steps as in example 1, wherein a catalyst in a raw material is 4-dimethylaminopyridine, the mass ratio of polyethyleneimine to the catalyst to an alcohol solvent is 1:0.1:98.9, and other raw materials are the same as in example 1.
Example 10
The preparation method of the composite nanofiltration membrane for lithium extraction in the salt lake comprises the same steps as in example 1, wherein a catalyst in a raw material is 4-dimethylaminopyridine, the mass ratio of polyethyleneimine to the catalyst to an alcohol solvent is 1:0.5:98.5, and other raw materials are the same as in example 1.
Example 11
The preparation method of the composite nanofiltration membrane for lithium extraction in the salt lake comprises the same steps as in example 1, wherein a catalyst in a raw material is 4-dimethylaminopyridine, the mass ratio of polyethyleneimine to the catalyst to an alcohol solvent is 0.5:0.3:99.2, and other raw materials are the same as in example 1.
Example 12
The preparation method of the composite nanofiltration membrane for lithium extraction in the salt lake comprises the same steps as in example 1, wherein a catalyst in a raw material is 4-dimethylaminopyridine, the mass ratio of polyethyleneimine to the catalyst to an alcohol solvent is 3:0.3:96.7, and other raw materials are the same as in example 1.
Comparative example 1
A preparation method of a composite nanofiltration membrane for extracting lithium from a salt lake comprises the same raw materials and steps (1) to (3) as in example 1, and post-modification treatment is not carried out.
Comparative example 2
The raw materials and the steps of the preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake are the same as those of the example 1, and no catalyst is added into the post-treatment solution.
The nanofiltration membranes prepared in the examples 1-12 and the comparative examples 1-2 are tested on a cross-flow membrane detection table, and the test conditions are as follows: (. 1) MgCl22000ppm of aqueous solution, 70psi of operating pressure, 25 ℃ of testing temperature and 6.5-7.5 of pH value, 2000ppm of LiCl aqueous solution, 70psi of operating pressure, 25 ℃ of testing temperature and 6.5-7.5 of pH value. The results obtained are shown in table 1:
TABLE 1
In table 1, water flux represents the amount of water permeated per unit membrane area per unit time, and the water flux represents the performance characteristics of the composite nanofiltration membrane in terms of efficiency; transmittance is the ability to transmit a particular component; the rejection rate represents the performance characteristics of the composite nanofiltration membrane in the transmission aspect.
Comparing the data in table 1, the following results were obtained:
comparing the test result data of example 1 and comparative example 1, it can be seen that: the permeability of the composite nanofiltration membrane magnesium chloride which is lack of post-treatment modification treatment is obviously increased, namely the magnesium-lithium separation effect is poor. Therefore, the post-treatment modification treatment step has a remarkable effect of improving the magnesium-lithium separation performance of the composite nanofiltration membrane.
Comparing the test result data of example 1 and comparative example 2, it can be seen that: if the post-treatment modified solution lacks the catalyst, the transmittance of the finally prepared composite nanofiltration membrane magnesium chloride cannot be reduced to the expected effect. Therefore, the catalyst has an unexpected effect on improving the magnesium-lithium separation performance of the composite nanofiltration membrane.
The data of the test results of comparative examples 1-3 show that: the composite nanofiltration membrane prepared by using piperazine or 1, 6-hexamethylene diamine as amine substances has two performances of water flux and rejection rate which are obviously superior to those of the composite nanofiltration membrane prepared by using m-phenylenediamine.
The data of the test results of comparative examples 1, 4-5 show that: the composite nanofiltration membrane prepared by adopting trimesoyl chloride as polybasic acyl chloride has better performance in the aspect of magnesium-lithium separation than the composite nanofiltration membrane prepared by adopting isophthaloyl dichloride or terephthaloyl dichloride as polybasic acyl chloride.
The data of the test results of comparative examples 1, 6-7 show that: the composite nanofiltration membrane prepared by using PEG400 as a water phase additive has better magnesium-lithium separation performance than the composite nanofiltration membrane prepared by using PEG200 and PEG800 as water phase additives. The reason is that: in the process of preparing the nascent state composite nanofiltration membrane, the molecular size of PEG400 is suitable and the aim of reducing the reaction rate is fulfilled, PEG200 does not achieve the aim of reducing the reaction rate, and the reaction defect can be caused due to the overlarge molecular size of PEG 800.
The test result data of comparative examples 8 to 12 show that: 4-dimethylamino pyridine is used as a catalyst, and when the mass ratio of polyethyleneimine to the catalyst to the alcohol solvent is 1:0.3:98.7, 1:0.1:98.9 or 1:0.5:98.5, 0.5:0.3:99.2, and 3:0.3:96.7, the prepared composite nanofiltration membrane has excellent magnesium and lithium separation performance.
In conclusion, the composite nanofiltration membrane provided by the embodiment of the invention has a remarkable improvement effect in magnesium-lithium separation compared with a common nanofiltration membrane; the preparation steps, raw material selection and raw material proportion of the composite nanofiltration membrane related by the embodiment of the invention are creatively improved.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A preparation method of a composite nanofiltration membrane for extracting lithium from a salt lake is characterized by comprising the following steps:
(1) preparing an aqueous phase solution: uniformly mixing an amine substance, a water-phase additive and deionized water to obtain a water-phase solution;
(2) preparing an oil phase solution: uniformly mixing polybasic acyl chloride and an oil phase solvent to obtain an oil phase solution;
(3) preparing a nascent state composite nanofiltration membrane: firstly, soaking a base film in an aqueous phase solution, and then soaking the base film in an oil phase solution; carrying out heat treatment on the basic membrane soaked by the oil phase solution to obtain a nascent state composite nanofiltration membrane;
(4) preparation of the post-treatment solution: mixing polyethyleneimine, a catalyst and an alcohol solvent to prepare a post-treatment solution;
(5) post-treatment modification: and (4) immersing the nascent-state composite nanofiltration membrane obtained in the step (3) into the post-treatment solution, and obtaining the composite nanofiltration membrane for extracting lithium from the salt lake after the post-treatment modification is completed.
2. The method for preparing the composite nanofiltration membrane for extracting lithium from the salt lake according to claim 1, wherein the amine substance in the step (1) is at least one of piperazine, 1, 6-hexamethylenediamine, 1, 4-diaminocyclohexane and m-phenylenediamine;
the water phase additive is at least one of polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 400 and polyethylene glycol 800;
the mass ratio of the amine substances, the water-phase additive and the deionized water in the water-phase solution is 0.5-3: 1-5: 92-98.5.
3. The method for preparing the composite nanofiltration membrane for extracting lithium from the salt lake according to claim 1, wherein the poly-acyl chloride in the step (2) is at least one of trimesoyl chloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, 4' -biphenyldicarbonyl chloride, succinyl chloride, glutaryl dichloride, adipoyl chloride and 1, 4-cyclohexanedicarbonyl chloride;
the oil phase solvent is at least one of n-hexane, cyclohexane and heptane;
the mass ratio of the polybasic acyl chloride to the oil phase solvent in the oil phase solution is 0.05-1: 99 to 99.95.
4. The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake according to claim 1, wherein the preparation method of the basic membrane in the step (3) is as follows:
weighing polyether sulfone resin and N-methyl pyrrolidone, mixing to prepare a solution, heating and stirring for 6 hours to prepare a uniformly dispersed casting film liquid, filtering, vacuum degassing, uniformly coating on a non-woven fabric on a film scraping machine, wherein the wet film thickness is 150-170 mu m, curing to form a film to obtain the base film, and refrigerating the base film in a freezer at 5 ℃ for later use.
5. The preparation method of the composite nanofiltration membrane for lithium extraction from the salt lake according to claim 1, wherein the nascent composite nanofiltration membrane in the step (3) is soaked in the aqueous solution for 15-25 s, and then a rubber roller is used for removing the residual aqueous solution on the surface of the basic membrane; soaking the base film in the oil phase solution for 10-20 s, and then removing the residual oil phase solution on the surface of the base film by using a rubber roller.
6. The preparation method of the composite nanofiltration membrane for extracting lithium from the salt lake according to claim 1, wherein the heat treatment method in the step (3) is to place the base membrane soaked in the oil phase solution in a 30-90 ℃ oven and keep the temperature for 1-30 min.
7. The method for preparing the composite nanofiltration membrane for extracting lithium from the salt lake according to claim 1, wherein the molecular weight of the polyethyleneimine obtained in the step (4) is 600, 1800, 10000 or 20000;
the catalyst is at least one of 4-dimethylamino pyridine, triethylamine and pyridine;
the alcohol solvent is at least one of methanol, ethanol and isopropanol.
8. The preparation method of the composite nanofiltration membrane for lithium extraction from the salt lake according to claim 1, wherein the mass ratio of polyethyleneimine, catalyst and alcohol solvent in the post-treatment solution in the step (4) is 0.5-3: 0.1-0.5: 96.5 to 99.4.
9. The preparation method of the composite nanofiltration membrane for lithium extraction from the salt lake according to claim 1, wherein the soaking time of the nascent state composite nanofiltration membrane in the step (4) in the post-treatment modified solution is 1-20 min.
10. A composite nanofiltration membrane for extracting lithium from a salt lake, which is characterized by being obtained by the preparation method of any one of claims 1 to 9.
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