CN117046310A - Fluoride modified pervaporation membrane and preparation method and application thereof - Google Patents
Fluoride modified pervaporation membrane and preparation method and application thereof Download PDFInfo
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- CN117046310A CN117046310A CN202310969692.XA CN202310969692A CN117046310A CN 117046310 A CN117046310 A CN 117046310A CN 202310969692 A CN202310969692 A CN 202310969692A CN 117046310 A CN117046310 A CN 117046310A
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- 239000012528 membrane Substances 0.000 title claims abstract description 77
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 title claims abstract description 48
- 238000005373 pervaporation Methods 0.000 title claims abstract description 35
- 238000002360 preparation method Methods 0.000 title abstract description 11
- 239000004205 dimethyl polysiloxane Substances 0.000 claims abstract description 58
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims abstract description 58
- -1 polydimethylsiloxane Polymers 0.000 claims abstract description 48
- 238000000926 separation method Methods 0.000 claims abstract description 33
- 125000003277 amino group Chemical group 0.000 claims abstract description 8
- 150000002222 fluorine compounds Chemical group 0.000 claims abstract description 4
- 239000002033 PVDF binder Substances 0.000 claims description 21
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 21
- 238000005266 casting Methods 0.000 claims description 19
- 239000005057 Hexamethylene diisocyanate Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 15
- 230000004048 modification Effects 0.000 claims description 14
- 238000012986 modification Methods 0.000 claims description 14
- 238000004132 cross linking Methods 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 claims description 11
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 10
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 10
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 10
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 claims description 10
- 239000003431 cross linking reagent Substances 0.000 claims description 8
- 125000000217 alkyl group Chemical group 0.000 claims description 6
- 125000004122 cyclic group Chemical group 0.000 claims description 6
- 229910052736 halogen Inorganic materials 0.000 claims description 6
- 150000002367 halogens Chemical group 0.000 claims description 6
- 238000001471 micro-filtration Methods 0.000 claims description 6
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 5
- 238000002791 soaking Methods 0.000 claims description 5
- 230000007480 spreading Effects 0.000 claims description 5
- 238000003892 spreading Methods 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 229910052801 chlorine Inorganic materials 0.000 claims description 3
- 238000004108 freeze drying Methods 0.000 claims description 3
- 229910052794 bromium Inorganic materials 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 239000000758 substrate Substances 0.000 claims description 2
- 150000001298 alcohols Chemical class 0.000 claims 2
- 230000004907 flux Effects 0.000 abstract description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052710 silicon Inorganic materials 0.000 abstract description 2
- 239000010703 silicon Substances 0.000 abstract description 2
- 235000013870 dimethyl polysiloxane Nutrition 0.000 description 43
- 239000000243 solution Substances 0.000 description 30
- 229910052731 fluorine Inorganic materials 0.000 description 10
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 9
- 239000011737 fluorine Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 6
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 6
- 230000007246 mechanism Effects 0.000 description 6
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 5
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical group CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000000855 fermentation Methods 0.000 description 3
- 230000004151 fermentation Effects 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- AQQBRCXWZZAFOK-UHFFFAOYSA-N 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoyl chloride Chemical compound FC(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(Cl)=O AQQBRCXWZZAFOK-UHFFFAOYSA-N 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- UKLDJPRMSDWDSL-UHFFFAOYSA-L [dibutyl(dodecanoyloxy)stannyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)O[Sn](CCCC)(CCCC)OC(=O)CCCCCCCCCCC UKLDJPRMSDWDSL-UHFFFAOYSA-L 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 239000012975 dibutyltin dilaurate Substances 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000004745 nonwoven fabric Substances 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 229920000728 polyester Polymers 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000002411 thermogravimetry Methods 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910002808 Si–O–Si Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 235000010633 broth Nutrition 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 1
- 125000004185 ester group Chemical group 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 239000013153 zeolitic imidazolate framework Substances 0.000 description 1
Classifications
-
- 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
- B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
- B01D61/362—Pervaporation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
- B01D17/08—Thickening liquid suspensions by filtration
- B01D17/085—Thickening liquid suspensions by filtration with membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0006—Organic membrane manufacture by chemical reactions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Water Supply & Treatment (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to a fluoride modified pervaporation membrane, and a preparation method and application thereof, and belongs to the technical field of membrane separation. The fluoride modified pervaporation membrane comprises a support layer and a selection layer; the selection layer is a fluoride modified aminated polydimethylsiloxane film, the fluoride modified aminated polydimethylsiloxane film takes a silicon bond as a main chain, and the fluoride is connected with an amino group on a side chain of the polydimethylsiloxane film through an amide bond. The fluoride modified pervaporation membrane prepared by the invention has higher separation performance on ethanol, the separation factor can reach 5.66-8.14, and the permeation flux is 727-8528 g.m ‑2 ·h ‑1 。
Description
Technical Field
The invention belongs to the technical field of membrane separation, and particularly relates to a fluoride modified pervaporation membrane, a preparation method and application thereof, in particular to a fluoride modified polydimethylsiloxane pervaporation membrane with high permeation flux and separation factors.
Background
Clean renewable bioethanol produced by biomass fermentation has great prospects for solving the existing energy crisis. However, recovery of bioethanol from fermentation broths still faces significant challenges due to the relatively low recovery rate. As an advanced separation technology, the membrane-based pervaporation technology has the potential of efficiently recovering bioethanol from fermentation liquor. The core of pervaporation technology is a membrane with high permeability and selective transport properties. Therefore, designing a membrane with high separation efficiency is a key to achieving efficient recovery of bioethanol.
Polydimethylsiloxane (PDMS) is currently widely studied as a membrane material for alcohol and water separation. However, the traditional PDMS membrane has low separation coefficient and extremely poor flux, and is not suitable for industrial application. In order to increase the permeability of PDMS membranes, researchers have explored different cross-linking agents, changing PDMS side groups, adding ZIFs particles, etc., to increase permeation flux and separation factors. However, the application of these film materials remains challenging due to the trade-off effect, defects, etc. Therefore, there is an urgent need to develop a membrane material that is easy to prepare, increases flux, and improves separation coefficient.
Patent publication No. CN202011199011 discloses a method of forming a selective layer by crosslinking a siloxane containing a fluorine group selected from the group consisting of-F, -CF with PDMS 3 ，-C 2 H 4 CF 3 At least one of the groups, and the chain segment of PDMS isAt least one of the following. The membrane mainly utilizes the hydrophobicity of the-F group to further improve the separation performance, the separation factor of the prepared membrane material is between 7 and 12, and the permeation flux is between 300 and 800 g.m -2 ·h -1 。
The current PDMS membrane material used for alcohol and water separation has a separation factor of 6-7 and a permeation flux of 1000 g.m -2 ·h -1 The flux and separation factor are low. Thus, there is a need to further explore effective methods of increasing separation factors and throughput.
Disclosure of Invention
The invention solves the technical problems of low permeation flux and low molecular factor of a pervaporation membrane in the prior art, and provides a fluoride modified pervaporation membrane, wherein a selection layer is a fluoride modified amino polydimethylsiloxane membrane, the fluoride modified amino polydimethylsiloxane membrane takes a silicon bond as a main chain, and the fluoride is connected with an amino group on a side chain of the polydimethylsiloxane membrane through an amide bond. The fluoride modified pervaporation membrane provided by the invention has high permeation flux and selectivity.
According to a first aspect of the present invention, there is provided a fluoride modified aminated polydimethylsiloxane pervaporation membrane comprising a support layer and a selection layer; the selection layer is a fluoride modified aminated polydimethylsiloxane film, the fluoride modified aminated polydimethylsiloxane film takes a silicon-oxygen bond as a main chain, and the fluoride is connected with uncrosslinked amino groups on an aminated polydimethylsiloxane side chain through an amide bond.
Preferably, the fluoride has the structural formula X-CO-R, wherein R is a fluorinated alkyl chain or cyclic group and X is halogen.
Preferably, X is Cl or Br.
Preferably, the support layer is a microfiltration membrane;
preferably, the microfiltration membrane is a polyvinylidene fluoride membrane.
According to another aspect of the present invention, there is provided a method for preparing any one of fluoride-modified aminated polydimethylsiloxane pervaporation membranes, comprising the steps of:
(1) Spreading a casting film solution on a base film serving as a supporting layer, wherein the casting film solution is a crosslinking solution of an aminated polydimethylsiloxane solution and a crosslinking agent hexamethylene diisocyanate solution;
(2) After film formation, adding fluoride solution for modification, wherein fluoride is connected with amine groups on the side chains of the polydimethylsiloxane film through amide bonds, and the fluoride modified polydimethylsiloxane pervaporation film is obtained.
Preferably, the fluoride has the structural formula X-CO-R, wherein R is a fluorinated alkyl chain or cyclic group and X is halogen.
Preferably, the time of the modification is 60 seconds or less.
Preferably, the preparation method of the base film comprises the following steps:
(1) Uniformly mixing polyvinylidene fluoride, triethyl phosphate, polyvinylpyrrolidone and N-methyl pyrrolidone to obtain homogeneous casting solution; the method comprises the steps of carrying out a first treatment on the surface of the
(2) And (3) spreading the casting film liquid obtained in the step (1) on a substrate, soaking in a water solidifying bath, removing residual triethyl phosphate, polyvinylpyrrolidone and N-methyl pyrrolidone, and freeze-drying to obtain the base film.
According to another aspect of the present invention there is provided the use of a fluoride modified aminated polydimethylsiloxane pervaporation membrane according to any of the preceding claims, for separating an alcohol from a mixture of alcohol and water.
Preferably, the temperature of the separation is from 25 ℃ to 60 ℃.
In general, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
(1) The fluoride modified polydimethylsiloxane membrane preparation method provided by the invention adopts novel aminated polydimethylsiloxane (MAPDMS) and Hexamethylene Diisocyanate (HDI) as cross-linking agents to form a membrane, and fluoride modification is carried out on amine groups which do not participate in cross-linking on the surface of the membrane and in the membrane to design the fluorine-containing pervaporation membrane material. The fluorine-containing pervaporation membrane prepared by the invention has strong hydrogen bond effect between the introduced fluorine and water, thereby being beneficial to damaging the ethanol water cluster structure and improving the separation performance of the membrane on ethanol water solution. When the fluoride modified MAPDMS pervaporation membrane of the invention is used for separating ethanol water solution with the concentration of 5wt.% at the temperature of 25-80 ℃, the separation factor can reach 5.66-8.14, and the permeation flux is 727-8528 g.m -2 ·h -1 。
(2) For pervaporation techniques, the separation of small molecule substances can be explained by a dissolution diffusion mechanism, whereas the dissolution process is mainly related to the affinity between the membrane surface groups and the substance to be separated. Based on the principle, the invention proposes that fluoride is introduced into the surface and the inside of the separation membrane, so that not only the separation performance and flux of the membrane to the ethanol water solution are improved by utilizing the strong hydrophobicity of the fluoride, but also the hydrogen bond between the ethanol water is broken by utilizing the stronger hydrogen bond action between fluorine-containing groups and water, thereby breaking the cluster structure of the fluoride and realizing the improvement of the membrane to the separation factor of the organic solution, such as the ethanol water solution.
(3) Compared with the traditional PMDS film, the fluorine-containing pervaporation film prepared by the invention has strong hydrophobicity and more free bodies, and is beneficial to improving the separation factor and the permeation flux. The traditional PDMS film is formed by taking Polydimethylsiloxane (PDMS) with hydroxyl groups as end groups as a film forming main body and crosslinking with a crosslinking agent ethyl orthosilicate (TEOS) under the action of a catalyst dibutyl tin Dilaurate (DBTL), wherein the essence of the crosslinking process is high-molecular polymerization reaction between the hydroxyl groups in the PDMS and ester groups in the TEOS. In the invention, hexamethylene Diisocyanate (HDI) is used as a cross-linking agent, a catalyst is not needed in comparison with TEOS cross-linking, the surface of a polydimethylsiloxane film formed after cross-linking is modified by adopting fluoride, the fluoride is selected from X-CO-R, R is fluorinated alkyl long chain or cyclic group, and X is halogen.
(4) The fluorine-containing pervaporation membrane main chain prepared by the invention is still a hydrophobic Si-O-Si main chain, so that the prepared membrane still has stronger stability and flexibility.
Drawings
FIG. 1 is a schematic diagram of a conventional polydimethylsiloxane film formation mechanism.
FIG. 2 is a schematic diagram of the structural mechanism of the fluorine-containing pervaporation membrane of the present invention.
FIG. 3 is a schematic diagram of the mechanism of the preparation process of the fluorine-containing pervaporation membrane according to the present invention.
FIG. 4 is a FT-IR characterization of MAPDMS-HDI-F15 membranes demonstrating that F15 successfully modifies MAPDMS-HDI membranes.
FIG. 5 is a thermogravimetric analysis of MAPDMS-HDI-F15-x(s), demonstrating the difference in degradation at different F15 modification times.
FIG. 6 is a benchmark plot of MAPDMS-HDI-F15-x(s) showing that the films prepared according to the present invention have better performance than other preparation methods.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The fluoride modified polydimethylsiloxane pervaporation membrane comprises a support layer and a selection layer, wherein the support layer is a microfiltration membrane, and the selection layer is a fluoride modified aminated polydimethylsiloxane membrane; the fluoride modified aminated polydimethylsiloxane membrane takes a silicon-oxygen bond as a main chain, the fluoride is positioned on a side chain, and fluoride molecules are connected with amine groups on the side chain of the polydimethylsiloxane membrane through an amide bond.
In some embodiments, the fluoride is selected from X-CO-R, R is a fluorinated alkyl long chain or cyclic group, and X is Cl, br halogen.
In some embodiments, the aminated polydimethylsiloxane (MAPDMS) isThe modified structural formula is
In some embodiments, the microfiltration membrane is a polyvinylidene fluoride membrane (PVDF).
The fluoride modified polydimethylsiloxane membrane has a separation factor of 5.66-8.14 and a permeation flux of 727-8528 g.m when separating an ethanol aqueous solution with a concentration of 5wt.% at 25-80 DEG C -2 ·h -1 。
The preparation method of the fluoride modified polydimethylsiloxane membrane comprises the following steps:
(1) Preparing a casting film liquid: crosslinking the aminated polydimethylsiloxane solution with Hexamethylene Diisocyanate (HDI) solution, and stopping further crosslinking of the HDI when the crosslinking concentration reaches about 34 m.Pa.s;
(2) Preparation of polydimethylsiloxane film: the casting film liquid is coated on a base film serving as a supporting layer in a scraping way, and is placed in an atmospheric environment to react for 12 hours at a film forming temperature of 40-60 ℃ to form a film;
(3) Fluoride modified polydimethylsiloxane membrane preparation: the polydimethylsiloxane film was spread flat in a plate frame, with fluoride solutions of different concentrations, or surface modifications were made for different times.
In some embodiments, the solvent used to prepare the fluoride modified polydimethylsiloxane membrane is n-hexane.
In some embodiments, the casting solution in step (1) is prepared as follows: polydimethyl siloxane: the mass ratio of the solvent is 1:10, and the cross-linking agent: the mass ratio of the solvent is 1:100.
In some embodiments, the base film is polyvinylidene fluoride (PVDF), and the method of making the base film comprises the steps of:
(1) Preparing PVDF casting solution: PVDF, triethyl phosphate (TEP), polyvinylpyrrolidone (PVP, mn=24000 g/mol) and N-methylpyrrolidone (NMP) were mixed in a flask, and stirred at 80 ℃ for 24 hours to obtain a homogeneous casting solution; placing the casting solution at room temperature for 48 hours, and removing bubbles;
(2) Preparing a PVDF base film: spreading the casting solution on a polyester non-woven fabric by using a scraper with the thickness of 150 mu m, immediately soaking the spread PVDF base film in a room temperature water coagulation bath, replacing deionized water for 6 hours, and soaking for 48 hours to completely remove TEP, PVP and NMP in the PVDF base film; finally, the PVDF base film was freeze-dried.
In some embodiments, the casting solution is formulated as follows: PVDF: TEP: PVP: the mass ratio of NMP is 18:30:6:46.
in some embodiments, the PVDF powder of the present invention is dried under vacuum at 80℃for 12 hours prior to use. PVDF casting solutions were prepared with PVDF (18 wt.%), PVP (6 wt.%), TEP (30 wt.%) and NMP (46 wt.%). After removing the air bubbles, the casting solution was knife coated on the polyester nonwoven fabric with a 200 μm doctor blade, and then transferred into a water bath for non-solvent induced phase separation (NIPS). In order to further remove NMP, PVP and TEP in the membrane, timely replacing PVDF deionized water, soaking for more than 12 hours, and finally obtaining the PVDF support membrane through freeze drying.
Example 1
An n-hexane solution of HDI (1 wt.%) was slowly added to a MAPDMS (10 wt.%) solution with rapid stirring. A casting solution of 2.4mL of HDI solution reached a suitable viscosity (34.2 mPa.s). Cast onto PVDF base film with a 100 μm blade. Subsequently, the film was dried in a graphene hotplate at 40 ℃ and further cross-linked to form a MAPDMS-HDI film, the cross-linking mechanism of which is completely different from that of conventional tetraethyl orthosilicate (TEOS) and Polydimethylsiloxane (PDMS) cross-linking agents, as shown in fig. 1 and 2, respectively. FIG. 3 is a schematic view showing the mechanism of the process for producing a fluorine-containing pervaporation membrane according to example 1.
Application testing
MAPDMS-HDI films were immersed in 10wt.% perfluorooctanoyl chloride (F15) solution for 0s, 15s, 30s, 45s and 60s, respectively, to form F15-x films, and the specific modification procedure is shown in FIG. 2. It was found by FTIR (fig. 4) that the absorption peak of carbonyl group (c=o) after F15 modification was red shifted, and that the absorption peak of c—f bond appeared after MAPDMS-HDI film modification, indicating successful modification of MAPDMS-HDI film. It was found by thermogravimetry (fig. 5) that as the grafting time of F15 increased, the degradation of the membrane increased gradually at around 200 ℃ due to thermal decomposition of the amide bonds in the membrane and that after equilibrium of degradation (after 700 ℃), the final residual amount increased, indicating successful incorporation of F15. Specific data on the pervaporation performance are shown in tables 1 and 2. Table 1 shows the separation performance at various modification times, and Table 2 shows the separation performance at various temperatures. From observation of table 1, it was found that, as the modification time increases, the permeation flux changes from rising to falling, and the separation factor gradually increases. From an examination of table 2, it was found that, as the temperature increases, the permeation flux gradually increases, and the separation factor changes in such a way that it increases and decreases.
F15 modified membrane material has optimal separation performance at the test temperature of 60 ℃ for 45 seconds, and permeation flux of 4584.07 g.m -2 ·h -1 The separation factor was 8.14, which is shown in fig. 6 in comparison with other membrane materials.
TABLE 1
TABLE 2
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. A fluoride modified aminated polydimethylsiloxane pervaporation membrane, characterized in that the fluoride modified aminated polydimethylsiloxane pervaporation membrane comprises a support layer and a selection layer; the selection layer is a fluoride modified aminated polydimethylsiloxane film, the fluoride modified aminated polydimethylsiloxane film takes a silicon-oxygen bond as a main chain, and the fluoride is connected with uncrosslinked amino groups on an aminated polydimethylsiloxane side chain through an amide bond.
2. The fluoride-modified, aminated polydimethylsiloxane pervaporation membrane of claim 1, wherein the fluoride has the structural formula X-CO-R, wherein R is a fluorinated alkyl chain or cyclic group and X is a halogen.
3. The fluoride-modified aminated polydimethylsiloxane pervaporation membrane of claim 2, wherein X is Cl or Br.
4. A fluoride-modified aminated polydimethylsiloxane pervaporation membrane according to any of claims 1 to 3, wherein said support layer is a microfiltration membrane;
preferably, the microfiltration membrane is a polyvinylidene fluoride membrane.
5. A method for preparing a fluoride-modified aminated polydimethylsiloxane pervaporation membrane according to any of claims 1 to 4, comprising the steps of:
(1) Spreading a casting film solution on a base film serving as a supporting layer, wherein the casting film solution is a crosslinking solution of an aminated polydimethylsiloxane solution and a crosslinking agent hexamethylene diisocyanate solution;
(2) After film formation, adding fluoride solution for modification, wherein fluoride is connected with amine groups on the side chains of the polydimethylsiloxane film through amide bonds, and the fluoride modified polydimethylsiloxane pervaporation film is obtained.
6. The method of claim 5, wherein the fluoride has the structural formula X-CO-R, wherein R is a fluorinated alkyl chain or cyclic group and X is a halogen.
7. The method according to claim 5 or 6, wherein the modification time is 60 seconds or less.
8. The method of producing as claimed in claim 5 or 6, wherein the method of producing the base film comprises the steps of:
(1) Uniformly mixing polyvinylidene fluoride, triethyl phosphate, polyvinylpyrrolidone and N-methyl pyrrolidone to obtain homogeneous casting solution; the method comprises the steps of carrying out a first treatment on the surface of the
(2) And (3) spreading the casting film liquid obtained in the step (1) on a substrate, soaking in a water solidifying bath, removing residual triethyl phosphate, polyvinylpyrrolidone and N-methyl pyrrolidone, and freeze-drying to obtain the base film.
9. Use of a fluorochemical modified aminated polydimethylsiloxane pervaporation membrane according to any of claims 1 to 4, for separating alcohols from a mixture of alcohols and water.
10. The use according to claim 9, wherein the separation temperature is 25 ℃ to 60 ℃.
Priority Applications (1)
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