CN114425244B - Preparation method and application of modified super-hydrophobic membrane based on polytetrafluoroethylene - Google Patents
Preparation method and application of modified super-hydrophobic membrane based on polytetrafluoroethylene Download PDFInfo
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- CN114425244B CN114425244B CN202210056902.1A CN202210056902A CN114425244B CN 114425244 B CN114425244 B CN 114425244B CN 202210056902 A CN202210056902 A CN 202210056902A CN 114425244 B CN114425244 B CN 114425244B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
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- 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
- B01D61/364—Membrane distillation
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- 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
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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
- B01D71/36—Polytetrafluoroethene
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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
- B01D2325/38—Hydrophobic membranes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
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Abstract
The invention provides a preparation method of a modified super-hydrophobic membrane based on polytetrafluoroethylene, which belongs to the technical field of membrane surface modification, wherein a hydrophobic polytetrafluoroethylene filter membrane is prepared by immersing a hydrophobic polytetrafluoroethylene filter membrane in a hot mixed aqueous solution of sodium hydroxide and dodecyl dimethyl benzyl ammonium chloride after being pre-wetted by ethanol, preserving heat and immersing the hydrophobic polytetrafluoroethylene filter membrane in a gamma-aminopropyl triethoxysilane ethanol solution, an acidic buffer solution with silica particles dispersed therein and a fluorosilane solution in sequence.
Description
Technical Field
The invention relates to the technical field of membrane surface modification, in particular to a preparation method and application of a modified super-hydrophobic membrane based on polytetrafluoroethylene.
Background
The membrane distillation is a membrane separation process with hydrophobic membrane material as a separation medium and steam pressure difference as a driving force. Unlike reverse osmosis desalination, the membrane distillation process has phase change and high energy consumption. Therefore, the application of the method generally has potential application prospects in the fields of inapplicability to reverse osmosis and relatively small treatment capacity, such as zero emission of industrial sewage, deep concentration of strong brine, movable miniaturized pure water preparation and the like.
The reuse of waste water is one of the effective measures for solving the shortage of water resources, taking coal chemical industry as an example, the sewage containing various organic matters and a large amount of salt needs to be subjected to complex pretreatment including flocculation, oxidation, precipitation, membrane filtration and concentration (such as ultra-micro filtration and reverse osmosis), and the salt content of the formed concentrated brine reaches 50000-80000mg/L, and then the concentrated brine is concentrated to obtain crystals and pure water. Compared with the existing concentration technology (such as natural evaporation, mechanical compression evaporation and multi-effect evaporation), the membrane distillation equipment has relatively low cost, low operating pressure and temperature, mild operating conditions and high quality of produced water. It would be of great competitive advantage if it were possible to utilize solar energy, waste heat, etc. as a heat source for the distillation process. The membrane distillation can also be used as a core component of movable water treatment equipment to provide clean water sources for many fresh water deficient areas. However, in the case of complex water systems, the fouling, scaling, wetting of hydrophobic membrane materials will lead to instability of the distillation process, and thus the hydrophobic stability and contamination resistance properties of the membrane materials are critical to the stable operation of the membrane distillation during the membrane distillation process.
Because of a certain price advantage, the modified PVDF (polyvinylidene fluoride) membrane is used as a hydrophobic membrane in the prior art, and the pollution resistance and the salt tolerance of the modified PVDF membrane are better than those of the PVDF original membrane, but the hydrophobic stability and the durability of the modified PVDF membrane are to be enhanced, and the flux is reduced, so that the distilled water production efficiency is reduced.
Disclosure of Invention
The invention provides a preparation method and application of a modified super-hydrophobic membrane based on polytetrafluoroethylene.
The aim of the invention is realized by adopting the following technical scheme:
a preparation method of a modified super-hydrophobic membrane based on polytetrafluoroethylene comprises the following steps:
s1, pre-wetting a hydrophobic polytetrafluoroethylene filter membrane with ethanol, immersing the filter membrane in a hot mixed aqueous solution of sodium hydroxide and dodecyl dimethyl benzyl ammonium chloride, and washing the filter membrane with deionized water after heat preservation and immersion are finished to obtain a first modified filter membrane;
s2, immersing the first modified filter membrane into an ethanol solution of gamma-aminopropyl triethoxysilane to obtain a second modified filter membrane;
s3, immersing the second modified filter membrane into an acidic buffer solution in which silica particles are dispersed to obtain a third modified filter membrane;
s4, immersing the third modified filter membrane into an ethanol solution of (1H, 2H-) perfluoro decyl triethoxysilane, and drying after the soaking is finished to obtain the modified super-hydrophobic membrane.
In some preferred embodiments, the pore size of the hydrophobic polytetrafluoroethylene filter is 0.1 μm.
In some preferred embodiments, the soaking temperature in the incubation step S1 is 60 ℃ and the soaking time is 3 hours.
In some preferred embodiments, the mass ratio of sodium hydroxide to dodecyldimethylbenzyl ammonium chloride in the aqueous mixture of step S1 is 5:1, with a total concentration of 6mg/mL.
In some preferred embodiments, the volume ratio of gamma-aminopropyl triethoxysilane to ethanol in step S2 is 1:100.
In some preferred embodiments, the acidic buffer solution of step S3 is an acetate buffer solution at ph=4, and the amount of silica particles dispersed is 0.05wt.%.
In some preferred embodiments, the volume ratio of (1H, 2H-) perfluorodecyl triethoxysilane to ethanol described in step S4 is 1:100.
The second object of the invention is to provide a modified super-hydrophobic membrane based on polytetrafluoroethylene, wherein the modified super-hydrophobic membrane is prepared by the preparation method.
The invention further aims to provide an application of the modified super-hydrophobic membrane, particularly an application in membrane distillation.
The beneficial effects of the invention are as follows:
aiming at the problem that stability and flux are difficult to be compatible in the prior art, the invention provides a polytetrafluoroethylene-based modified super-hydrophobic membrane, the modification improves the hydrophobicity of a PTFE membrane, meanwhile, the flux is not reduced or even improved, and particularly, the invention takes a hydrophobic polytetrafluoroethylene filter membrane as a substrate, the hydrophobic polytetrafluoroethylene filter membrane is treated by NaOH-DDBAC mixed solution, then surface amino is introduced by silane coupling agent, silica to be negatively charged is introduced by impregnation under an acidic condition by utilizing electrostatic effect, and finally, the modified PTFE membrane is prepared by fluorosilane treatment and drying.
Drawings
The invention will be further described with reference to the accompanying drawings, in which embodiments do not constitute any limitation of the invention, and other drawings can be obtained by one of ordinary skill in the art without inventive effort from the following drawings.
FIG. 1 is a graph of water droplet interaction with PTFF film;
FIG. 2 is a schematic diagram of water droplets and F-SiO 2 Graph of PTFE film interaction force;
FIG. 3 is a schematic diagram of water in PTFF film and F-SiO 2 Comparative graph of contact angle on @ PTFE film;
FIG. 4 shows water in PTFF film and F-SiO 2 Roll on PTFE film versus graph;
FIG. 5 is a schematic diagram of the structure of the membrane distillation apparatus according to the experimental example;
FIG. 6 is a PTFE membrane and F-SiO 2 The @ PTFE membrane is plotted against time for the hot water side 1.5wt.%, 3.5wt.%, 5.5wt.% NaCl solution flux, respectively.
Detailed Description
The invention will be further described with reference to the following examples.
The embodiment of the invention relates to a modified super-hydrophobic membrane, and a preparation method thereof comprises the following steps:
(1) Completely prewetting a dried hydrophobic PTFE film with ethanol, immersing the dried hydrophobic PTFE film in a mixed solution of NaOH and DDBAC (dodecyl dimethyl benzyl ammonium chloride), putting the mixed solution into an oven together, immersing the dried hydrophobic PTFE film for 3 hours at the temperature of 60 ℃, filtering out the dried hydrophobic PTFE film and washing the dried hydrophobic PTFE film with deionized water to obtain an alkaline treated PTFE film;
the concentration of NaOH and DDBAC in the mixed solution is 5mg/mL and 1mg/mL respectively;
(2) Soaking the PTFE membrane obtained in the step (1) in an APTES (gamma-aminopropyl triethoxysilane) -ethanol solution with the concentration of 1% (v/v) for 1h, so that amine groups and positive charges are introduced into the surface of the membrane;
(3) Immersing the positively charged PTFE film obtained in (2) in a dispersion of SiO 2 Soaking in acetate buffer solution (pH=4) for 2.5 hr to obtain SiO 2 A @ PTFE film;
acetic acid content in the buffer solution is 0.0375mL/L, siO 2 The content of the particles is 0.5g/L;
(4) SiO prepared in step (3) 2 @PTFImmersing E film in 1% (v/v) of (1H, 2H-) perfluorodecyl triethoxysilane-ethanol solution for 10min, vacuum drying at 120deg.C for 20min to obtain the modified super-hydrophobic film (marked as F-SiO) 2 @PTFE)。
Experimental example
1. Comparing unmodified PTEF film, determining water drop and PTEF film and F-SiO 2 The interaction force of the PTFE film is measured according to the attached figures 1-2;
2. measurement of water on PTEF film and F-SiO by comparison with unmodified PTEF film 2 Contact angle and rolling property of the @ PTFE film, and the measurement results are shown in FIGS. 3-4;
3. continuous testing was performed in a membrane distillation apparatus with unmodified PTEF membrane as a comparison, the membrane distillation apparatus being schematically shown in FIG. 5, for determining PTFE membrane and F-SiO 2 The flux change of the @ PTFE film on NaCl solutions (pure water on the cold water side) with different concentrations on the hot water side is shown in FIG. 6.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.
Claims (9)
1. The preparation method of the modified super-hydrophobic membrane based on polytetrafluoroethylene is characterized by comprising the following steps of:
s1, pre-wetting a hydrophobic polytetrafluoroethylene filter membrane with ethanol, immersing the filter membrane in a hot mixed aqueous solution of sodium hydroxide and dodecyl dimethyl benzyl ammonium chloride, and washing the filter membrane with deionized water after heat preservation and immersion are finished to obtain a first modified filter membrane;
s2, immersing the first modified filter membrane into an ethanol solution of gamma-aminopropyl triethoxysilane to obtain a second modified filter membrane;
s3, immersing the second modified filter membrane into an acidic buffer solution in which silica particles are dispersed to obtain a third modified filter membrane;
s4, immersing the third modified filter membrane into an ethanol solution of (1H, 2H-) perfluoro decyl triethoxysilane, and drying after the soaking is finished to obtain the modified super-hydrophobic membrane.
2. The method for preparing a modified super-hydrophobic membrane based on polytetrafluoroethylene according to claim 1, wherein the pore size of the hydrophobic polytetrafluoroethylene membrane is 0.1 μm.
3. The method for preparing a modified super-hydrophobic membrane based on polytetrafluoroethylene according to claim 1, wherein the soaking temperature in the step S1 is 60 ℃ and the soaking time is 3h.
4. The method for preparing a modified super-hydrophobic membrane based on polytetrafluoroethylene according to claim 1, wherein the mass ratio of sodium hydroxide to dodecyl dimethyl benzyl ammonium chloride in the mixed aqueous solution in the step S1 is 5:1, and the total concentration is 6mg/mL.
5. The method for preparing a modified super-hydrophobic membrane based on polytetrafluoroethylene according to claim 1, wherein the volume ratio of gamma-aminopropyl triethoxysilane to ethanol in the step S2 is 1:100.
6. The method for preparing a modified superhydrophobic film based on polytetrafluoroethylene according to claim 1, wherein the acidic buffer solution in step S3 is an acetate buffer solution having ph=4, and the dispersion amount of silica particles is 0.05wt.%.
7. The method for preparing a modified super-hydrophobic membrane based on polytetrafluoroethylene according to claim 1, wherein the volume ratio of (1 h,2 h-) perfluorodecyl triethoxysilane to ethanol in step S4 is 1:100.
8. A modified superhydrophobic film based on polytetrafluoroethylene produced by the production process according to any one of claims 1-7.
9. Use of the modified superhydrophobic film according to claim 8 in film distillation.
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| CN114891258B (en) * | 2022-05-24 | 2023-07-25 | 东北电力大学 | Preparation method of film with firm interface crosslinking layer on surface |
| CN115364700A (en) * | 2022-08-02 | 2022-11-22 | 广州大学 | Polyvinylidene fluoride-based modified super-hydrophobic membrane, and preparation method and application thereof |
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| CN103387690B (en) * | 2012-05-09 | 2015-01-14 | 中国科学院大连化学物理研究所 | Preparation method of cross-linking type composite anion-exchange membrane |
| WO2015084266A1 (en) * | 2013-12-05 | 2015-06-11 | Nanyang Technological University | A composite nanofiber membrane for membrane distillation and a method of fabrication thereof |
| CN106390764B (en) * | 2015-07-28 | 2018-10-12 | 北京工业大学 | A kind of super-hydrophobic oleophobic method of modifying of perforated membrane |
| CN105413488B (en) * | 2015-12-11 | 2018-03-06 | 上海交通大学 | A kind of preparation method and applications of super-hydrophobic film |
| CN109939573A (en) * | 2017-12-20 | 2019-06-28 | 扬州中福生物技术有限公司 | The hydrophobically modified method of PTFE filter membrane |
| WO2019155446A1 (en) * | 2018-02-12 | 2019-08-15 | Ypf Tecnología S.A. | Method of preparation of new super-hydrophobic membranes and membranes obtained by said method |
| CN109011919A (en) * | 2018-08-21 | 2018-12-18 | 安徽工业大学 | A kind of improved silica Nano sol solution and the micropore film filtering material for high humidity clarifying smoke and preparation method thereof |
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| CN113318617B (en) * | 2021-04-15 | 2022-05-31 | 中山大学 | Crystallization-resistant hydrophobic modified membrane and preparation method and application thereof |
| CN113230911A (en) * | 2021-05-25 | 2021-08-10 | 浙江工业大学 | Preparation method of amphiphobic polytetrafluoroethylene membrane |
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