CN115318115A - Micro-channel type hydrophobic membrane, preparation method and application thereof, and prediction method for bromine extraction yield by gas membrane method - Google Patents
Micro-channel type hydrophobic membrane, preparation method and application thereof, and prediction method for bromine extraction yield by gas membrane method Download PDFInfo
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- CN115318115A CN115318115A CN202210808787.9A CN202210808787A CN115318115A CN 115318115 A CN115318115 A CN 115318115A CN 202210808787 A CN202210808787 A CN 202210808787A CN 115318115 A CN115318115 A CN 115318115A
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- 239000012528 membrane Substances 0.000 title claims abstract description 205
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 title claims abstract description 121
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 title claims abstract description 121
- 229910052794 bromium Inorganic materials 0.000 title claims abstract description 121
- 238000000034 method Methods 0.000 title claims abstract description 67
- 230000002209 hydrophobic effect Effects 0.000 title claims abstract description 33
- 238000000605 extraction Methods 0.000 title claims abstract description 30
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 239000002994 raw material Substances 0.000 claims abstract description 53
- 230000008569 process Effects 0.000 claims abstract description 19
- 239000002105 nanoparticle Substances 0.000 claims abstract description 16
- 239000002033 PVDF binder Substances 0.000 claims abstract description 15
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims abstract description 15
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 90
- 239000000243 solution Substances 0.000 claims description 81
- 239000007788 liquid Substances 0.000 claims description 42
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 39
- 238000006243 chemical reaction Methods 0.000 claims description 31
- 238000011282 treatment Methods 0.000 claims description 29
- 238000009792 diffusion process Methods 0.000 claims description 28
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 claims description 24
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 24
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims description 23
- 229910000077 silane Inorganic materials 0.000 claims description 23
- 125000002091 cationic group Chemical group 0.000 claims description 22
- 238000004132 cross linking Methods 0.000 claims description 19
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 16
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 16
- 239000003513 alkali Substances 0.000 claims description 15
- 239000002243 precursor Substances 0.000 claims description 15
- 238000001035 drying Methods 0.000 claims description 13
- 238000005805 hydroxylation reaction Methods 0.000 claims description 13
- QRPMCZNLJXJVSG-UHFFFAOYSA-N trichloro(1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-henicosafluorodecyl)silane Chemical compound FC(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)[Si](Cl)(Cl)Cl QRPMCZNLJXJVSG-UHFFFAOYSA-N 0.000 claims description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 11
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 9
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 9
- 230000004913 activation Effects 0.000 claims description 9
- 230000033444 hydroxylation Effects 0.000 claims description 9
- 239000011259 mixed solution Substances 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 230000035484 reaction time Effects 0.000 claims description 9
- 229910044991 metal oxide Inorganic materials 0.000 claims description 8
- 150000004706 metal oxides Chemical class 0.000 claims description 8
- -1 alkyl trimethoxy silane Chemical compound 0.000 claims description 7
- 239000000084 colloidal system Substances 0.000 claims description 7
- 150000004756 silanes Chemical class 0.000 claims description 7
- 239000002585 base Substances 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- JMXKSZRRTHPKDL-UHFFFAOYSA-N titanium ethoxide Chemical compound [Ti+4].CC[O-].CC[O-].CC[O-].CC[O-] JMXKSZRRTHPKDL-UHFFFAOYSA-N 0.000 claims description 6
- CPUDPFPXCZDNGI-UHFFFAOYSA-N triethoxy(methyl)silane Chemical compound CCO[Si](C)(OCC)OCC CPUDPFPXCZDNGI-UHFFFAOYSA-N 0.000 claims description 6
- 238000007256 debromination reaction Methods 0.000 claims description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 4
- 239000012670 alkaline solution Substances 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- 239000012466 permeate Substances 0.000 claims description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 3
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 claims description 3
- 150000004645 aluminates Chemical class 0.000 claims description 3
- NCGBFHRHXQDSQM-UHFFFAOYSA-N chloro(fluoro)silane Chemical compound F[SiH2]Cl NCGBFHRHXQDSQM-UHFFFAOYSA-N 0.000 claims description 3
- HMMGMWAXVFQUOA-UHFFFAOYSA-N octamethylcyclotetrasiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1 HMMGMWAXVFQUOA-UHFFFAOYSA-N 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 3
- 239000004246 zinc acetate Substances 0.000 claims description 3
- 238000006460 hydrolysis reaction Methods 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- 239000011787 zinc oxide Substances 0.000 claims description 2
- 230000004907 flux Effects 0.000 abstract description 29
- 230000003075 superhydrophobic effect Effects 0.000 abstract description 7
- 230000003746 surface roughness Effects 0.000 abstract description 5
- 238000005457 optimization Methods 0.000 abstract description 2
- 125000001165 hydrophobic group Chemical group 0.000 abstract 1
- 239000000758 substrate Substances 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 31
- 239000007789 gas Substances 0.000 description 31
- 235000019441 ethanol Nutrition 0.000 description 28
- 239000012510 hollow fiber Substances 0.000 description 28
- 238000000926 separation method Methods 0.000 description 14
- 238000010438 heat treatment Methods 0.000 description 13
- 238000004140 cleaning Methods 0.000 description 11
- 238000002474 experimental method Methods 0.000 description 10
- 238000005086 pumping Methods 0.000 description 10
- 238000003756 stirring Methods 0.000 description 10
- 238000005406 washing Methods 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 238000012546 transfer Methods 0.000 description 8
- 239000008367 deionised water Substances 0.000 description 7
- 229910021641 deionized water Inorganic materials 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 6
- 239000011148 porous material Substances 0.000 description 6
- 125000004122 cyclic group Chemical group 0.000 description 5
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 238000002791 soaking Methods 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- 238000005576 amination reaction Methods 0.000 description 4
- 238000011221 initial treatment Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 235000012239 silicon dioxide Nutrition 0.000 description 4
- 238000009736 wetting Methods 0.000 description 4
- 230000033558 biomineral tissue development Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000012527 feed solution Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 244000020998 Acacia farnesiana Species 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 235000010643 Leucaena leucocephala Nutrition 0.000 description 2
- 125000000129 anionic group Chemical group 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- JGJLWPGRMCADHB-UHFFFAOYSA-N hypobromite Inorganic materials Br[O-] JGJLWPGRMCADHB-UHFFFAOYSA-N 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 2
- 238000001256 steam distillation Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- LLZRNZOLAXHGLL-UHFFFAOYSA-J titanic acid Chemical compound O[Ti](O)(O)O LLZRNZOLAXHGLL-UHFFFAOYSA-J 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
- B01D71/34—Polyvinylidene fluoride
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
-
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/09—Bromine; Hydrogen bromide
- C01B7/096—Bromine
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- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/32—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond
- D06M11/36—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond with oxides, hydroxides or mixed oxides; with salts derived from anions with an amphoteric element-oxygen bond
- D06M11/38—Oxides or hydroxides of elements of Groups 1 or 11 of the Periodic System
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- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/77—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with silicon or compounds thereof
- D06M11/79—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with silicon or compounds thereof with silicon dioxide, silicic acids or their salts
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- D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
- D06M13/50—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with organometallic compounds; with organic compounds containing boron, silicon, selenium or tellurium atoms
- D06M13/51—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond
- D06M13/513—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond with at least one carbon-silicon bond
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- D06M13/50—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with organometallic compounds; with organic compounds containing boron, silicon, selenium or tellurium atoms
- D06M13/51—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond
- D06M13/513—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond with at least one carbon-silicon bond
- D06M13/517—Compounds with at least one carbon-metal or carbon-boron, carbon-silicon, carbon-selenium, or carbon-tellurium bond with at least one carbon-silicon bond containing silicon-halogen bonds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2325/00—Details relating to properties of membranes
- B01D2325/02—Details relating to pores or porosity of the membranes
- B01D2325/028—Microfluidic pore structures
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- D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
- D06M2101/16—Synthetic fibres, other than mineral fibres
- D06M2101/18—Synthetic fibres consisting of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
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- D06M2200/10—Repellency against liquids
- D06M2200/12—Hydrophobic properties
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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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
Abstract
The invention discloses a micro-channel type PVDF hydrophobic membrane for bromine extraction from bromine-containing raw materials, a preparation method thereof and a bromine extraction process by a gas membrane method. The nano-scale particles grow on the film substrate and are grafted with hydrophobic groups, so that the surface roughness of the film is improved, the surface energy is reduced, the hydrophobicity of the film is improved, and the super-hydrophobic capability of the film is realized. The micro-channel type hydrophobic membrane greatly prolongs the service life and flux of the membrane, and the prepared hydrophobic membrane can better improve the bromine extraction process, improve the bromine extraction efficiency and realize stable operation of the process. A yield prediction model in the bromine extraction process by the gas membrane method is provided, and the model can predict the total bromine yield of the bromine extraction process by the gas membrane method under different process conditions, so that process optimization is realized.
Description
Technical Field
The invention relates to a micro-channel type hydrophobic membrane, a preparation method and application thereof, and a yield prediction model of a bromine extraction process by a gas membrane method, belonging to the technical field of membrane separation.
Background
The industrialized bromine extraction method mainly adopts the processes of steam distillation and air blowing. But the steam distillation method has high requirement on the grade of raw materials and the air blowing method has larger energy consumption. Novel bromine extraction processes such as an adsorption method, an extraction method, a membrane method and the like are developed at home and abroad aiming at researching a bromine extraction technology with wide application range and low energy consumption. The membrane method for extracting bromine comprises two aspects of extracting bromine by a gaseous membrane method and extracting bromine by a liquid membrane method.
The gas membrane method is a membrane separation technology using vapor pressure as a driving force, water and substances in an ionic state cannot permeate through membrane pores in the separation process due to the hydrophobicity of a membrane material, and volatile substances can diffuse to the other side through the membrane pores to be absorbed and enriched. The method is suitable for separating and extracting certain volatile substances from the aqueous solution, and has the characteristics of simple process, high efficiency, energy conservation, good selectivity and the like.
In the membrane separation process, the membrane is easy to be wetted, so that the membrane cannot run for a long time in the membrane separation process, and the membrane separation effect is influenced. The separation membrane with insufficient hydrophobicity can be slowly soaked in membrane pores by feed liquid in the operation process, so that steam cannot permeate through the separation membrane, flux attenuation is caused, and the separation performance of the separation membrane is reduced. Therefore, the key to prepare the composite membrane is to carry out super-hydrophobic modification on the PVDF hollow fiber membrane and maintain the flux.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the existing separation membrane material applied to extracting bromine by a gas membrane method has the problems of fast flux attenuation and poor separation performance.
The invention can endow the membrane with anti-wetting function by carrying out super-hydrophobic modification on the membrane surface, effectively reduce the membrane pore wetting phenomenon in the membrane separation process, and provides a yield prediction method of the gas membrane bromine extraction process, so as to predict the total bromine yield of the gas membrane bromine extraction process under different process conditions. The technical scheme of the invention maintains the pore structure of the membrane while enhancing the hydrophobicity of the membrane so as to realize the anti-wetting and anti-pollution capabilities of the membrane and realize high membrane flux.
A microchannel hydrophobic membrane, comprising:
a base film;
and an oxide nanoparticle layer covering the surface of the base film;
the surface of the oxide nano-particle is grafted with a hydrophobic compound.
The base film is made of PVDF.
The oxide nanoparticles are selected from titanium oxide, zinc oxide, aluminum oxide or silicon oxide.
The hydrophobic compound is selected from halosilanes.
The preparation method of the hydrophobic membrane of the micro-channel comprises the following steps:
step 3, immersing the cationic porous membrane obtained in the step 2 into a solution containing metal oxide colloid to cover the surface with a metal oxide layer;
and 4, immersing the porous membrane obtained in the step 3 into a solution containing halogenated silane, carrying out grafting reaction on the surface, and drying to obtain the hydrophobic membrane of the micro-channel.
In the step 1, the porous membrane is a porous PVDF membrane; the alkali solution is one of lithium hydroxide, sodium hydroxide, potassium hydroxide and other alkali solutions, the concentration of the alkali solution is 1-5 mol/L, the reaction temperature of surface hydroxylation is 30-80 ℃, and the reaction time is 1-6 hours.
In the step 2, the cationic silane is selected from one of long-carbon chain alkyl trimethoxy silane (HDTMS), methyl Triethoxysilane (MTES), octamethylcyclotetrasiloxane (D4), 3-Aminopropyltriethoxysilane (APTES), and the like, and 3-aminopropyltriethoxysilane APTES is preferred; the mass fraction of the cationic silane solution is 1-5 wt%, and the treatment time is 6-24 hours.
In the step 3, the preparation method of the solution containing the metal oxide colloid comprises the following steps:
mixing the mineralized precursor with an alcohol solvent, adding ammonia water, and performing hydrolysis reaction to obtain a solution containing metal oxide colloid.
The mineralized precursor is selected from one of tetraethyl silicate, tetraethyl titanate, trimethyl aluminate, zinc acetate and the like, and preferably tetraethyl silicate; the content of ammonia water is 15-30wt%; the volume ratio of the mineralized precursor to the alcohol solvent is 1-20:100, respectively; the volume ratio of the mixed solution obtained by mixing the mineralized precursor and the alcohol solvent to ammonia water is 1:0.5 to 1:3; the contact time of the porous membrane and the solution is 3 to 15 hours.
In step 4, the halosilane is a long-chain chloro-fluoro silane, such as triethoxy-1H, 2H-heptadecafluorodecyl silane, perfluorodecyl trichlorosilane, etc., preferably perfluorodecyl trichlorosilane PFTS.
The mass fraction of the halogenated silane is 1 to 5wt percent; the crosslinking reaction temperature is 40-80 ℃; the crosslinking reaction time is 6-24 hours.
The application of the microchannel hydrophobic membrane in extracting bromine by a gas membrane method.
The application comprises the following steps: contacting bromine-containing solution with a hydrophobic membrane of the microchannel, applying negative pressure on a permeation side to enable bromine to permeate the membrane layer, and condensing and collecting; the bromine-containing solution has a concentration of 10-10000ppm and a temperature of 10-90 ℃; the negative pressure range is-0.1 to-0.9 bar.
The application also comprises a prediction process of the debromination rate, and the method comprises the following steps:
s1, measuring the bromine concentration C of the initial raw material liquid under different temperature conditions 0 And is fixed toResidual bromine concentration C of the feed solution after time Deltat t The reaction rate r was calculated by the following formula A ：
r A ＝(C 0 -C t )/Δt；
S2, calculating diffusion rate constants k under different temperature conditions according to the following formula:
(-r A )＝kc 0
s3, performing linear fitting according to the following formula, and regressing a frequency factor k 0 And diffusion activation energy E:
r is the ideal gas constant and T is the temperature;
and S4, applying the equation obtained by fitting in the S3 to k under different temperature conditions, and substituting the equation into the equation in the S2 to calculate the debromination rate.
Advantageous effects
The membrane surface super-hydrophobic modification means combines low surface energy and high surface roughness, so that the physical and chemical properties of the membrane surface are changed, and a super-hydrophobic surface with anti-wetting capacity is formed.
The surface of the membrane is treated by alkali, so that abundant hydroxyl groups are generated on the surface of the membrane to provide anchoring sites for the growth of mineralized particles. The surface of the film is positively charged by treating the surface of the film with cationic silane, and after the mineralized precursor is hydrolyzed, colloid particles (such as titanium hydroxide, titanium oxide, silicon oxide and the like) with negative charges are generated, and the positive charges on the surface of the film can enable the mineralized particles with the negative charges to be more fully combined on the surface of the film through electrostatic induction. The growth of the mineralized nanoparticles increases the roughness of the surface of the membrane, and after the roughness is improved, an air layer can be formed among particles of the membrane layer to form a Cassie State State, so that the hydrophobic effect can be enhanced; the grafted halogenated silane can reduce the surface chemical energy and has the effect of hydrophobic modification. It should be noted that for hydrophobic modification, the increase in roughness can introduce an air layer between the particles, thereby enhancing the hydrophobic effect of the film layer, i.e., forming a "Cassie State" State. Generally, by adopting the technical means, the surface roughness of the film can be increased, the surface chemical energy of the film can be reduced, the hydrophobicity of the film is greatly enhanced, and the organic/inorganic film structure improves the chemical stability of the film, so that the film has certain acid and alkali resistance.
Drawings
Fig. 1 is a surface SEM photograph of the multi-channel PVDF membrane prepared in example 1.
FIG. 2 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 1 and example 1.
FIG. 3 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 1 and comparative example 2.
FIG. 4 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 3 and example 1.
FIG. 5 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 4 and example 1.
FIG. 6 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 5 and example 1.
FIG. 7 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 6 and example 1.
FIG. 8 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 7 and example 2.
FIG. 9 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 8 and example 2.
FIG. 10 is a graph showing the yield/flux in extracting bromine by a gas membrane method in comparative example 9 and example 2.
Figure 11 is a linear fit of bromine flux to bromine-containing feed solution concentration.
FIG. 12 is a graph of diffusion rate constants at different temperatures.
FIG. 13 is a graph showing the contact angle of a water droplet on the surface of a PVDF hollow fiber hydrophobic membrane prepared under preferred conditions.
Fig. 14 is a schematic view of diffusion of gaseous bromine in a microchannel-type hydrophobic membrane.
FIG. 15 is a schematic view of a process flow for extracting bromine by a gas membrane method.
Detailed Description
The preparation method of the microchannel PVDF hydrophobic membrane is detailed as follows:
preparing an alkaline solution, immersing the cleaned hollow fiber membrane into the alkaline solution, and heating and reacting for a certain time to realize surface hydroxylation to obtain a primary treatment membrane;
preparing a cationic silane solution, cleaning the primary treatment membrane with deionized water, immersing the primary treatment membrane into the cationic silane solution, and oscillating the primary treatment membrane for a period of time by using a shaker to obtain a secondary treatment membrane;
mixing the mineralized precursor with ethanol, stirring to form a uniform solution, adding ammonia water to prepare a mineralized mixed solution, immersing the secondary treatment film cleaned by the ethanol into the mineralized solution, and oscillating for a period of time by a shaker to obtain a tertiary treatment film;
cleaning the third treatment membrane with ethanol, and drying to obtain a fourth treatment membrane;
preparing a mixed solution of halosilane and ethanol, immersing the four-time treatment film obtained by drying into an ethanol solution of halosilane, heating and stirring, and carrying out cross-linking reaction for a period of time to obtain a five-time treatment film;
and drying the five-time treated film at a certain temperature to obtain a finished film.
In one embodiment, the alkali solution is one of alkali solutions such as lithium hydroxide, sodium hydroxide, potassium hydroxide and the like;
in one embodiment, the cationic silane solution is long-chain alkyl trimethoxy silane (HDTMS), methyl Triethoxysilane (MTES), one of octamethylcyclotetrasiloxane (D4), 3-Aminopropyltriethoxysilane (APTES), etc., preferably 3-aminopropyltriethoxysilane APTES;
in one embodiment, the mineralized precursor is one of tetraethyl silicate TEOS, tetraethyl titanate Ti (OEt) 4, trimethyl aluminate, zinc acetate, and the like, preferably tetraethyl silicate TEOS;
in one embodiment, the halosilane is a long chain chloro, fluoro silane such as triethoxy-1H, 2H-heptadecafluorodecyl silane, perfluorodecyl trichlorosilane, etc., preferably perfluorodecyl trichlorosilane PFTS;
in one embodiment, the concentration of the alkali solution is 1 to 5mol/L;
in one embodiment, the heating temperature is 30-80 ℃;
in one embodiment, the heating reaction time is 1 to 6 hours;
in one embodiment, the mass fraction of the cationic silane solution is 1-5 wt%;
in one embodiment, the treatment time of the cationic silane solution is 6 to 24 hours;
in one embodiment, the ammonia content is 25wt%;
in one embodiment, the volume ratio of the mineralized precursor to ammonia water is 1:0.5 to 1:3;
in one embodiment, the treatment time of the mineralization solution is 3 to 15 hours;
in one embodiment, the mass fraction of the halosilane is 1 to 5wt%;
in one embodiment, the crosslinking reaction temperature is 40-80 ℃;
in one embodiment, the crosslinking reaction is carried out for a period of 6 to 24 hours.
The following experimental steps of the bromine extraction process by a gas film method are as follows: step 1, preheating a raw material liquid to a specified temperature, pumping the raw material liquid into a hollow fiber membrane shell pass through a pump, pumping the raw material liquid back into a raw material liquid storage tank after passing through the membrane shell pass, and realizing the cyclic absorption of the raw material; step 2, providing negative pressure on the hollow fiber membrane tube pass by using a vacuum pump, so that bromine in the raw material liquid passes through a membrane hole after being evaporated, enters the tube pass from the shell pass, and is condensed and recovered to obtain bromine; the preheating temperature of the raw material liquid is 30-90 ℃; the negative pressure provided by the tube pass of the membrane is-0.5-0.9 bar.
The procedure in the following examples is: preheating 1000ppm bromine-containing raw material liquid to 50 ℃, setting the flow rate to be 60ml/min by a pump, pumping into a hollow fiber membrane shell pass, pumping back to a raw material liquid storage tank after passing through the membrane shell pass, and realizing the cyclic absorption of the raw material; and (3) providing negative pressure of-0.60 bar on the tube pass of the hollow fiber membrane by using a vacuum pump, so that bromine in the raw material liquid passes through the membrane hole after being evaporated, enters the shell pass from the tube pass, and is condensed and recovered by using liquid nitrogen to obtain bromine. The membrane material used in this example was the membrane material of example 1.
Example 1
(1) Pretreating a PVDF hollow fiber membrane: soaking the pre-selected hollow fiber membrane in absolute ethyl alcohol for 1h, washing off impurities, and then washing with deionized water.
(2) Surface hydroxyl/amination treatment: preparing 2mol/L NaOH solution, immersing the hollow fiber membrane in the step (1) in the NaOH solution, heating to 50 ℃ and reacting for 1 hour to realize surface hydroxylation; preparing an APTES solution of 3-aminopropyltriethoxysilane with the mass fraction of 2wt%, immersing the membrane subjected to alkali treatment in the APTES solution of 3-aminopropyltriethoxysilane, oscillating for 24 hours by a shaker, and cleaning with absolute ethyl alcohol;
(3) And (3) growing the silicon dioxide nanoparticles: tetraethyl silicate TEOS and ethanol are mixed according to the weight ratio of 5: mixing according to the volume ratio of 100, stirring to form a uniform solution, adding 25wt% of ammonia water, wherein the volume ratio of tetraethyl silicate TEOS to ethanol to ammonia water is 5:100:4 preparing a mineralized mixed solution, immersing the membrane in the step (2) into the mineralized solution, oscillating for 6 hours by a shaking table, cleaning by ethanol, and drying;
(4) Perfluorodecyl trichlorosilane grafting: preparing an ethanol solution of PFTS, wherein the mass fraction of PFTS is 1%, immersing the membrane in the step (3) into the ethanol solution of PFTS, heating to 60 ℃, stirring, performing crosslinking reaction for 12h, and drying for 12h at 70 ℃ to obtain a finished membrane. FIG. 1 is a field emission scanning electron microscope image of a microchannel PVDF hydrophobic membrane, which shows that the surface of the membrane is rough and uniform in nanometer scale.
Comparative example 1
The differences between the comparative example 1 and the example 1 are: the shaking time of the mineralized mixed solution in a shaking table is shortened, and the shaking table is shaken for 3 hours.
The influence of the mineralization reaction time on the membrane is examined, and based on the results of two experiments for preparing the membrane, as shown in fig. 2, the mineralization reaction time of the comparative example 1 is shortened relative to the example 1, so that the oxide nanoparticles growing on the surface of the membrane are reduced, the roughness of the surface of the membrane is lower, the hydrophobicity of the membrane is reduced compared with the example 1, the performance of the membrane is influenced, and the flux and the yield of the comparative example 1 in the early stage of the process are slightly reduced compared with the example 1.
Comparative example 2
The differences from example 1 are: the time of perfluorodecyl trichlorosilane grafting crosslinking reaction is prolonged, and the crosslinking reaction lasts 24 hours.
The influence of the halosilane graft-crosslinking reaction time on the membrane was examined, and based on the results of two experiments for preparing the membrane shown in fig. 3, the halosilane graft-crosslinking reaction time was prolonged in comparative example 2, so that the excess halosilane blocked part of the membrane pores on the membrane surface, thereby affecting the membrane flux per unit time, and causing a certain decrease in both flux and yield in comparative example 2 compared with example 1.
Comparative example 3
The differences from example 1 are: the cationic silane treatment step is eliminated.
(1) Pretreating a PVDF hollow fiber membrane: soaking the pre-selected hollow fiber membrane in absolute ethyl alcohol for 1h, washing off impurities, and then washing with deionized water.
(2) Surface hydroxylation treatment: preparing 2mol/L NaOH solution, immersing the hollow fiber membrane in the step (1) in the NaOH solution, heating to 50 ℃, reacting for 1 hour to realize surface hydroxylation, and cleaning with deionized water;
(3) And (3) growing the silicon dioxide nanoparticles: tetraethyl silicate TEOS and ethanol are mixed according to the proportion of 5: mixing according to the volume ratio of 100, stirring to form a uniform solution, adding 25wt% of ammonia water, wherein the volume ratio of tetraethyl silicate TEOS to ethanol to ammonia water is 5:100:4 preparing a mineralized mixed solution, immersing the membrane in the step (2) into the mineralized solution, oscillating for 6 hours by a shaking table, cleaning by ethanol and drying;
(4) Perfluorodecyl trichlorosilane grafting: preparing an ethanol solution of PFTS, wherein the mass fraction of PFTS is 1%, immersing the membrane in the step (3) into the ethanol solution of PFTS, heating to 60 ℃, stirring, performing crosslinking reaction for 12h, and drying for 12h at 70 ℃ to obtain a finished membrane.
The step of treating the membrane with cationic silane is omitted in comparative example 3, and based on the results of two experiments for preparing the membrane shown in fig. 4, the membrane surface is not treated with cationic silane, so that negatively charged oxide nanoparticles cannot be attracted to the membrane surface through electrostatic induction, colloidal particles cannot grow on the membrane surface, the membrane surface roughness is low, and the superhydrophobic property of the membrane cannot be realized, so that the flux and yield of the comparative example 3 are reduced in the whole process compared with those of example 1.
Comparative example 4
The differences from example 1 are: the cationic silane treatment was replaced with an anionic modifier treatment.
(1) Pretreating a PVDF hollow fiber membrane: soaking the pre-selected hollow fiber membrane in absolute ethyl alcohol for 1h, washing off impurities, and then washing with deionized water.
(2) Surface hydroxyl/amination treatment: preparing 2mol/L NaOH solution, immersing the hollow fiber membrane in the step (1) into the NaOH solution, heating to 50 ℃ and reacting for 1h to realize surface hydroxylation; preparing a sodium dodecyl benzene sulfonate solution with the mass fraction of 2wt%, immersing the membrane subjected to alkali treatment into the sodium dodecyl benzene sulfonate solution, oscillating in a table for 24 hours, and cleaning with absolute ethyl alcohol;
(3) And (3) growing the silicon dioxide nanoparticles: tetraethyl silicate TEOS and ethanol are mixed according to the weight ratio of 5: mixing according to the volume ratio of 100, stirring to form a uniform solution, adding 25wt% of ammonia water, wherein the volume ratio of tetraethyl silicate TEOS to ethanol to ammonia water is 5:100:4 preparing a mineralized mixed solution, immersing the membrane in the step (2) into the mineralized solution, oscillating for 6 hours by a shaking table, cleaning by ethanol and drying;
(4) Perfluorodecyl trichlorosilane grafting: preparing an ethanol solution of PFTS, wherein the mass fraction of PFTS is 1%, immersing the membrane in the step (3) into the ethanol solution of PFTS, heating to 60 ℃, stirring, performing crosslinking reaction for 12h, and drying at 70 ℃ for 12h to obtain the finished membrane.
Comparative example 4 the cationic silane treatment was replaced with the anionic modifier treatment, so that the surface of the membrane was negatively charged, and the colloidal particles could not grow successfully due to mutual repulsion with the negatively charged nanoparticles, which resulted in lower membrane roughness and poorer hydrophobic properties, and significantly decreased bromine yield and flux, and the results of two experiments for preparing the membrane are shown in fig. 5, which illustrates the necessity of the cationic silane treatment.
Comparative example 5
The differences from example 1 are: the treatment step of the mineralized precursor solution is eliminated.
(1) Pretreating a PVDF hollow fiber membrane: soaking the pre-selected hollow fiber membrane in absolute ethyl alcohol for 1h, washing off impurities, and then washing with deionized water.
(2) Surface hydroxyl/amination treatment: preparing 2mol/L NaOH solution, immersing the hollow fiber membrane in the step (1) into the NaOH solution, heating to 50 ℃ and reacting for 1h to realize surface hydroxylation; preparing an APTES solution of 3-aminopropyltriethoxysilane with the mass fraction of 2wt%, immersing the membrane subjected to alkali treatment in the APTES solution of 3-aminopropyltriethoxysilane, oscillating for 24 hours by a shaker, and cleaning with absolute ethyl alcohol;
(3) Perfluorodecyl trichlorosilane grafting: preparing an ethanol solution of PFTS, wherein the mass fraction of PFTS is 1%, immersing the membrane in the step (2) into the ethanol solution of PFTS, heating to 60 ℃, stirring, performing crosslinking reaction for 12h, and drying for 12h at 70 ℃ to obtain a finished membrane.
Comparative example 5 cancels the treatment step of the mineralized precursor solution, directly performs the halogenated silane grafting, reduces the surface energy of the membrane only by treating the surface of the membrane with perfluorodecyl trichlorosilane, but still has low surface roughness, and does not realize the super-hydrophobic property of the membrane. Affecting the performance of the film resulted in a significant decrease in both bromine yield and flux compared to comparative example 5 compared to example 1, based on the results of two experiments to make the film, shown in figure 6, illustrating the necessity of treatment of the mineralized precursor solution.
Comparative example 6
The differences from example 1 are: the halosilane crosslinking step is eliminated.
(1) Pretreating a PVDF hollow fiber membrane: soaking the pre-selected hollow fiber membrane in absolute ethyl alcohol for 1h, washing off impurities, and then washing with deionized water.
(2) Surface hydroxyl/amination treatment: preparing 2mol/L NaOH solution, immersing the hollow fiber membrane in the step (1) into the NaOH solution, heating to 50 ℃ and reacting for 1h to realize surface hydroxylation; preparing an APTES solution of 3-aminopropyltriethoxysilane with the mass fraction of 2wt%, immersing the membrane subjected to alkali treatment in the APTES solution of 3-aminopropyltriethoxysilane, oscillating for 24 hours by a shaker, and cleaning with absolute ethyl alcohol;
(3) And (3) growing the silicon dioxide nanoparticles: tetraethyl silicate TEOS and ethanol are mixed according to the weight ratio of 5: mixing according to the volume ratio of 100, stirring to form a uniform solution, adding 25wt% of ammonia water, wherein the volume ratio of tetraethyl silicate TEOS to ethanol to ammonia water is 5:100:4 preparing a mineralized mixed solution, immersing the membrane in the step (2) into the mineralized solution, oscillating for 6 hours by a shaking table, cleaning by ethanol, and drying to obtain a finished membrane.
Comparative example 6, in which the halosilane crosslinking reaction step was eliminated, is shown in FIG. 7 based on the results of two experiments for preparing a film. In the comparison example, the halogenated silane crosslinking reaction is not carried out, so that the oxide nanoparticles growing on the surface of the membrane improve the roughness of the membrane, but the oxide on the surface of the membrane improves the surface energy of the membrane, so that the surface of the membrane is more hydrophilic on the whole, and the implementation of the bromine extraction process by a gas membrane method is not facilitated. As can be seen from FIG. 7, bromine extraction based on the film prepared in comparative example 6 could not be accomplished, indicating the necessity of carrying out the halosilane crosslinking reaction.
Comparative example 7
The differences from example 1 are: the bromine concentration of the raw material liquid is changed.
Preheating a 500ppm bromine-containing raw material solution to 50 ℃, setting the flow rate to be 60ml/min by a pump, pumping the raw material solution into a hollow fiber membrane shell pass, pumping the raw material solution back to a raw material solution storage tank after passing through the membrane shell pass, and realizing the cyclic absorption of the raw material; providing negative pressure of-0.60 bar on the tube pass of the hollow fiber membrane by using a vacuum pump, enabling bromine in the raw material liquid to pass through a membrane hole after being evaporated, entering the shell pass from the tube pass, and condensing and recycling by using liquid nitrogen to obtain bromine;
comparative example 8
The differences from example 1 are: the preheating temperature of the raw material liquid is changed.
Preheating 1000ppm bromine-containing raw material liquid to 70 ℃, setting the flow rate to be 60ml/min by a pump, pumping into a hollow fiber membrane shell pass, pumping back to a raw material liquid storage tank after passing through the membrane shell pass, and realizing the cyclic absorption of the raw material; providing negative pressure of-0.60 bar on the tube pass of the hollow fiber membrane by using a vacuum pump, enabling bromine in the raw material liquid to pass through a membrane hole after being evaporated, entering the shell pass from the tube pass, and condensing and recycling by using liquid nitrogen to obtain bromine;
comparative example 9
The differences from example 1 are: the flow rate of the feed liquid was changed.
Preheating a raw material liquid containing 1000ppm of bromine to 50 ℃, setting the flow rate to be 30ml/min by a pump, pumping the raw material liquid into a hollow fiber membrane shell pass, pumping the raw material liquid back to a raw material liquid storage tank after passing through the membrane shell pass, and realizing the cyclic absorption of the raw material; providing negative pressure of-0.60 bar on the tube pass of the hollow fiber membrane by using a vacuum pump, enabling bromine in the raw material liquid to pass through a membrane hole after being evaporated, entering the shell pass from the tube pass, and condensing and recycling by using liquid nitrogen to obtain bromine;
the mass transfer mechanism of the bromine extraction process by the air film method is as follows: bromine vapor is heated and evaporated from the raw material liquid, and under the pushing of the pressure difference between two sides of the hydrophobic membrane, the bromine vapor is diffused from the feed side to the absorption side. According to the power function model:
the diffusion rate constants at different temperatures can be determined, where (-r) A ) As the reaction rate, k is the diffusion rate constant, c A Alpha is the number of reaction stages for reactant concentration.
And then the Allen-Wus equation is utilized:
the diffusion activation energy E and the frequency factor k can be calculated 0 。
Based on the above theoretical derivation, the prediction model proposed in this patent is as follows:
the modeling process in the invention is mainly used for predicting the total bromine yield of the bromine extraction process by the gas-film method under different process conditions.
The prediction comprises the following steps:
s1, carrying out air film bromine extraction on bromine water, and respectively recording the residual bromine concentration and yield in raw materials after a certain time under the conditions of different bromine contents in raw material liquid;
s2, calculating the membrane flux of the raw material liquid under the conditions of different bromine contents and concentrations, wherein the membrane flux is represented by an equation
Calculating, namely performing linear fitting on the bromine flux under different concentration conditions and the initial bromine concentration in the raw material liquid, solving a linear correlation coefficient, and determining the reaction stage number;
wherein J is membrane flux, V is total mass of bromine passing through the membrane, S is effective membrane area, and t is feed liquid retention time;
s3, carrying out gas film bromine extraction on bromine water, and respectively recording the residual bromine concentration in the raw material after a certain time under different preheating temperatures of the raw material liquid to obtain the total bromine yield under different preheating temperatures;
s4, substituting the initial bromine concentration of the raw material liquid and the residual bromine concentration of the raw material after bromine extraction for a certain time into an equation
K values at different raw material temperatures can be obtained;
wherein (-r) A ) As the reaction rate, k is the diffusion rate constant, c A In terms of reactant concentration, α is the number of reaction stages.
S5, substituting diffusion rate constants k and corresponding raw material temperatures at different temperatures into an equation
And deformation equation thereof
In (1), drawing a relationship diagram of lnk and 1/TThe slope of the straight line is-E/R, and the intercept of the straight line with the same vertical coordinate is lnk 0 . From this, the frequency factor k is determined 0 And a diffusion activation energy E.
S6, according to the obtained frequency factor k 0 And diffusion activation energy E, substitution equation
The diffusion rate constant k value under the set temperature can be calculated and substituted into the equation
And under the temperature, predicting the residual bromine concentration of the raw material liquid after a certain time and calculating the debromination rate of the raw material according to the initial bromine content of the raw material liquid and the set temperature, thereby optimizing the process.
More specifically:
when the bromine concentration of the raw material liquid is 500ppm,1000ppm and 2000ppm, the 5min flux is 0.54832 kg/(m) 2 *h)，1.02002kg/(m 2 * h) And 1.99117 kg/(m) 2 * h) The yields were 0.545,0.519,0.503, respectively.
A linear fit was made to the bromine flux and bromine-containing feed solution concentration as shown in figure 11. Linear correlation coefficient R 2 And the mass transfer rate is 0.99995, the linear dependence of the flux and the concentration is extremely strong, namely the main mass transfer driving force of the diffusion process of the gaseous bromine passing through the membrane is the bromine vapor concentration difference or the steam pressure difference at two sides of the membrane, and therefore the mass transfer diffusion of the bromine vapor can be inferred to be a first-order reaction, namely alpha =1 in a power function model. For the experiments of bromine separation and recovery under different bromine concentrations in the raw material liquid, the bromine concentration and the bromine flux are in an obvious linear relationship and accord with a first-stage reaction kinetic model, and the diffusion process of bromine vapor passing through the membrane is a first-stage reaction.
Thus, the power function model can be:
(-r A )＝kc A
the variation of the brine bromine concentration at 30 ℃, 50 ℃ and 70 ℃ within 5min is measured respectively, and the diffusion rate constant k at different temperatures is calculated. Substituting into a first-order reaction rate equation:
lnc A -lnc A0 ＝kt
the diffusion rate constants k at 30 deg.C, 50 deg.C and 70 deg.C can be calculated as k =0.0995,0.1320,0.1800min -1 The lnk values at 30 ℃, 50 ℃ and 70 ℃ are-2.3076, -2.025, -1.7148. The diffusion rate constant can be plotted against temperature as shown in fig. 12.
Can obtain lnk and 1/T linear correlation coefficient R 2 =0.9962, which shows that lnk has a linear relationship with 1/T, verifies the conclusion of setting parameter α =1 in the power function model.
The slope of a fitting straight line in the graph of the diffusion rate constant and the temperature function is-E/R, and the intercept intersected with the ordinate axis is lnk 0 . The diffusion activation energy E is 12.775kJ/mol, the frequency factor k is obtained 0 ＝15.665。
The chemical reaction activation energy is generally 42-420 kJ/mol, while the diffusion activation energy of bromine vapor in the bromine extraction process by the gas membrane method is only 12.775kJ/mol, which indicates that the process is not a chemical reaction process, but a physical process, namely, the mass transfer driving force of the bromine vapor in the diffusion process through the hydrophobic membrane microchannel is the vapor pressure difference at two sides of the membrane. The mass transfer equation calculation can be performed using a power function model.
Bromine dissolved in water in a bromine extraction process by a gas membrane method is changed into gas state from liquid state at a certain temperature, and is separated from the system under the promotion of pressure difference and concentration difference by utilizing the good air permeability of a hydrophobic membrane, so that the aim of purifying and separating bromine is fulfilled.
The diffusion activation energy is 12.775kJ/mol, and the frequency factor k 0 Substitution of =15.665 into arrhenius equation:
the mass transfer diffusion equation of bromine in the gas film process is obtained as follows:
the bromine yield is predicted by the mass transfer diffusion equation through a gas film method at 90 ℃, and the diffusion rate constant k =0.22774min at 90 ℃ can be obtained by the formula -1 Substituted into the following formula:
lnc A -lnc A0 ＝kt
when the bromine-containing solution as the raw material solution was 1000ppm, the residual bromine content of the raw material solution after extracting bromine by a gas film method at 90 ℃ for 5 minutes was 320ppm, and the yield was 0.680.
A verification experiment is carried out on the gas film bromine extraction process at the temperature of 90 ℃, the residual bromine content of the raw material liquid after 5 minutes of bromine extraction by the gas film method is 320ppm, the yield is 0.680, and the residual bromine content is consistent with the predicted residual bromine content, which shows that the predicted total bromine yield of bromine extraction by the gas film method at the temperature of 90 ℃ is more accurate. In the same way, the total bromine yield under other temperature, concentration and flow rate conditions can be predicted, so that the optimization of process conditions is realized.
In conclusion, a yield prediction model under the system is provided for the bromine extraction process by the gas film method, the total bromine yield under other conditions is predicted, experiments prove that the model is more accurate, and the predicted total bromine yield is better matched with the total bromine yield in the experiments.
Claims (10)
1. A hydrophobic membrane of microchannel type, comprising:
a base film;
and an oxide nanoparticle layer covering the surface of the base film
The surface of the oxide nanoparticles is grafted with a hydrophobic compound.
2. The hydrophobic membrane of claim 1, wherein the base membrane is selected from the group consisting of PVDF;
the oxide nanoparticles are selected from titanium oxide, zinc oxide, aluminum oxide or silicon oxide;
the hydrophobic compound is selected from halosilanes.
3. The method for preparing a hydrophobic membrane of microchannel type according to claim 1, comprising the steps of:
step 1, immersing a porous membrane in an alkaline solution to hydroxylate the surface;
step 2, immersing the porous membrane obtained in the step 1 into a solution containing cationic silane to modify the surface with cationic silane;
step 3, immersing the cationic porous membrane obtained in the step 2 into a solution containing metal oxide colloid to cover the surface with a metal oxide layer;
and 4, immersing the porous membrane obtained in the step 3 into a solution containing halogenated silane, carrying out grafting reaction on the surface, and drying to obtain the hydrophobic membrane of the micro-channel.
4. The method according to claim 3, wherein in the step 1, the porous membrane is a porous PVDF membrane; the alkali solution is one of lithium hydroxide, sodium hydroxide, potassium hydroxide and other alkali solutions, the concentration of the alkali solution is 1-5 mol/L, the reaction temperature of surface hydroxylation is 30-80 ℃, and the reaction time is 1-6 hours.
5. The method according to claim 3, wherein in step 2, the cationic silane is selected from long-chain alkyl trimethoxy silane (HDTMS), methyl triethoxy silane (MTES), octamethylcyclotetrasiloxane (D4), 3-aminopropyl triethoxy silane (APTES), and preferably 3-aminopropyl triethoxy silane APTES; the mass fraction of the cationic silane solution is 1-5 wt%, and the treatment time is 6-24 hours.
6. The method according to claim 3, wherein the step 3 of preparing the solution containing the metal oxide colloid comprises the steps of: mixing the mineralized precursor with an alcohol solvent, adding ammonia water, and performing hydrolysis reaction to obtain a solution containing metal oxide colloid;
the mineralized precursor is selected from one of tetraethyl silicate, tetraethyl titanate, trimethyl aluminate, zinc acetate and the like, and preferably tetraethyl silicate; the content of ammonia water is 15-30wt%; the volume ratio of the mineralized precursor to the alcohol solvent is 1-20:100, respectively; the volume ratio of the mixed solution obtained by mixing the mineralized precursor and the alcohol solvent to ammonia water is 1:0.5 to 1:3; the contact time between the porous membrane and the solution is 3 to 15 hours.
7. The method of claim 3, wherein in step 4, the halosilane is a long-chain chloro-fluoro silane, such as triethoxy-1H, 2H-heptadecafluorodecyl silane, perfluorodecyl trichlorosilane, etc., preferably perfluorodecyl trichlorosilane PFTS;
the mass fraction of the halogenated silane is 1 to 5 weight percent; the crosslinking reaction temperature is 40-80 ℃; the crosslinking reaction time is 6-24 hours.
8. Use of the hydrophobic microchannel membrane of claim 1 for bromine extraction by gas membrane process.
9. Use according to claim 8, characterized in that it comprises the following steps: contacting the bromine-containing solution with a hydrophobic membrane of the micro-channel, applying negative pressure on the permeation side to enable bromine to permeate the membrane layer, and condensing and collecting; the bromine-containing solution has a concentration of 10-10000ppm and a temperature of 10-90 ℃; the negative pressure range is-0.1 to-0.9 bar.
10. The use according to claim 8, further comprising a process for predicting a debromination rate comprising the steps of:
s1, measuring the bromine concentration C of the initial raw material liquid under different temperature conditions 0 And the residual bromine concentration C of the raw material solution after a certain time Deltat t The reaction rate r was calculated by the following formula A ：
r A ＝(C 0 -C t )/Δt；
S2, calculating diffusion rate constants k under different temperature conditions according to the following formula:
(-r A )＝kc 0
s3, performing linear fitting according to the following formula, and regressing a frequency factor k 0 And diffusion activation energy E:
r is the ideal gas constant and T is the temperature;
and S4, applying the equation obtained by fitting in the S3 to k under different temperature conditions, and substituting the k into the equation in the S2 to calculate the debromination rate.
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| CN117771945A (en) * | 2024-02-28 | 2024-03-29 | 泰州禾益新材料科技有限公司 | Preparation method of homogeneous blend fiber reinforced PVDF ultrafiltration membrane |
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