CN-122006505-A - Durable superhydrophobic uniform pore separation membrane and preparation method and application thereof

Abstract

The invention belongs to the technical field of membrane distillation, and discloses a durable superhydrophobic uniform pore separation membrane, a preparation method and application thereof, wherein a comonomer, a polymer membrane material, a solvent, a pore-forming agent and an initiator are mixed in proportion, stirred at constant temperature, and subjected to in-situ copolymerization reaction under the atmosphere of nitrogen and the conventional dissolution temperature of the polymer membrane material to form a casting solution containing a strong hydrophobic crosslinkable copolymer A-B, the casting solution is then prepared into a nascent liquid membrane, the interfacial phase separation of the surface of the liquid membrane is accelerated by short-time spray treatment, and then the membrane is immersed into a coagulating bath for crosslinking and curing, so that the durable superhydrophobic uniform pore separation membrane is obtained, wherein the water contact angle is more than 150 degrees, and the tensile strength is more than 3.5 MPa. The preparation method is simple to operate, the reaction condition is mild, the lasting super-hydrophobization and pore size uniformity of the membrane material are realized in the membrane preparation process, and the anti-wetting capability of the membrane is promoted.

Inventors

• WU CHUNRUI
• GAO HAIFU
• HE LONGFEI
• YAN HONGJIN
• Han Qijia

Assignees

• 沧州市天津工业大学研究院
• 天津工业大学

Dates

Publication Date

20260512

Application Date

20260414

Claims (10)

1. 1. A preparation method of a durable super-hydrophobic uniform pore separation membrane is characterized by comprising the following steps: (1) Mixing a comonomer, a polymer film material, a solvent, a pore-forming agent and an initiator in proportion, stirring at constant temperature, and initiating in-situ copolymerization reaction under the atmosphere of nitrogen and the conventional dissolution temperature of the polymer film material to form a casting film solution containing a strong hydrophobic cross-linkable copolymer A-B, wherein the comonomer comprises a strong hydrophobic molecule A and a cross-linkable molecule B, the strong hydrophobic molecule A is a molecule simultaneously containing an unsaturated bond and a polyfluoroalkyl group, and the cross-linkable molecule B is a molecule simultaneously containing an unsaturated bond and a siloxane group; (2) Preparing the casting film liquid into a nascent liquid film, and placing the nascent liquid film in a spraying environment to obtain a surface pre-solidified nascent liquid film; (3) And immersing the surface pre-solidified nascent liquid film into a coagulating bath for crosslinking and solidifying to obtain the durable super-hydrophobic uniform pore separation film.
2. 2. The method according to claim 1, wherein the strongly hydrophobic molecule A comprises one or more of 1H, 2H-perfluorodecyl acrylate, 1H, 2H-perfluoro-1-dodecene, 1H, 2H-perfluoro-1-decene, 1H, 2H-perfluoro-1-hexene, perfluorohexyl ethyl acrylate, 2-perfluorooctyl ethyl methacrylate, 2-perfluorooctyl ethyl acrylate, and 2-perfluorobutyl ethyl methacrylate.
3. 3. The method of manufacturing according to claim 1, characterized in that: the crosslinkable molecule B comprises one or more than two of vinyl dimethyl ethoxy silane, vinyl methyl diethoxy silane, vinyl trimethoxy silane, dimethyl ethoxy formyloxy silane, 3-methacryloxypropyl methyl dimethoxy silane, gamma-methacryloxypropyl trimethoxy silane and 3-acryloxypropyl trimethoxy silane; the initiator comprises azobisisobutyronitrile azobisisovaleronitrile, azobisisoheptonitrile, and azodiisovaleronitrile azo-diisoheptonitrile.
4. 4. The method of claim 1, wherein the molar ratio of the strongly hydrophobic molecule A to the crosslinkable molecule B is 1:1 to 10:1.
5. 5. The method according to claim 1, wherein the polymer film material comprises one or more of polyvinylidene fluoride, polyvinylidene fluoride-chlorotrifluoroethylene and polyvinylidene fluoride-hexafluoropropylene, the solvent comprises one or more of dimethylacetamide, dimethylformamide and N-methylpyrrolidone, and the pore-forming agent comprises one or more of methanol, ethanol, propylene glycol and N-butanol.
6. 6. The method of claim 1, wherein the total amount of the polymer film material is 11-19 wt%, the solvent is 45.90-77.99 wt%, the pore-forming agent is 10-25 wt%, the comonomer is 1-10 wt%, and the initiator is 0.01-0.1 wt%.
7. 7. The process according to claim 1, wherein the stirring temperature in the step (1) is 60-90 ℃ and the dissolution time is 4-24 hours.
8. 8. The method according to claim 1, wherein the nascent membrane is placed in a spraying environment for 30s-200s, the spraying flow is 200mL/h-500mL/h, and the coagulation bath is deionized water, and the temperature is 20 ℃ to 70 ℃.
9. 9. A durable superhydrophobic uniform pore separation membrane according to any one of claims 1-8, wherein the membrane body has a strong hydrophobic cross-linked interpenetrating network structure and the surface of the membrane has a pleated high-roughness micro/nano structure with an open pore structure.
10. 10. Use of the durable superhydrophobic uniform pore separation membrane of claim 9 in membrane distillation.

Description

Durable superhydrophobic uniform pore separation membrane and preparation method and application thereof Technical Field The invention belongs to the technical field of membrane distillation, and relates to a durable superhydrophobic uniform pore separation membrane, and a preparation method and application thereof. Background Severe water pollution and fresh water resource shortage have become key problems affecting human survival and development. Desalination from seawater, high-salinity water and wastewater has become a necessary requirement for ecological civilization construction and sustainable development of economy and society. The membrane distillation is a novel membrane separation process which takes a hydrophobic microporous membrane as a separation medium and takes a vapor pressure difference as a driving force, can be used for treating high-concentration and high-pollution brine under the conditions of high desalination rate close to 100% and relatively mild operation (such as pressure close to atmospheric pressure and temperature lower than the boiling point of water), realizes 100% removal of non-volatile solutes, preferentially permeates and efficiently recovers volatile components in water, and has been widely used in the fields of treatment of domestic wastewater and industrial wastewater, medicine, food processing and the like. With the deep research and application expansion of the membrane distillation technology, the problems of membrane pollution and membrane wetting of the hydrophobic membrane in the running process are increasingly prominent, and the hydrophobic membrane has become the key for influencing the quality, efficiency, stability and service life of the produced water of the membrane distillation. It was found that constructing a superhydrophobic film with micro/nano-scale roughness structure with low interfacial energy is key to effectively alleviate problems such as film contamination and wetting. Following this principle, researchers have developed various superhydrophobic films by means of external modifications or changes in intrinsic properties. External modification includes applying a coating or surface treatment to the surface of the existing film material to enhance its superhydrophobic properties. Materials such as fluorinated silica nanoparticles, carbon nanotubes, metal Organic Frameworks (MOFs), etc. have been used to build layered rough superhydrophobic functional layers on film surfaces to improve their contamination resistance, anti-wetting properties. However, the deposition and modification process is time consuming and consumes large amounts of chemical resources, which is difficult to scale. In addition, there is a risk that the deposited components on the membrane will fall out and dissolve during operation, which not only damages the superhydrophobicity of the membrane, but also raises concerns about potential environmental toxicity. Intrinsic modification can improve the surface structure of the film by controlling the phase separation behavior inherent in the film formation process, imparting superhydrophobic properties thereto. Common methods include non-solvent induced phase separation (NIPS), vapor Induced Phase Separation (VIPS). In the NIPS method, crystal nucleus, hydrogen bond can be adopted to induce molecular chain crystallization and crystal form transformation of the membrane material to construct a surface-body super-hydrophobic microstructure or a soft coagulant (such as alcohols) is adopted to delay the phase separation process, so that the molecular chain rearrangement crystallization of the membrane material is promoted, and a microsphere coarse membrane structure is constructed to improve the hydrophobicity of the membrane. In the VIPS method, the hydrophobicity of the film is enhanced by exposing the scraped nascent liquid film to a gaseous non-solvent for a long period of time, allowing it to absorb the vapor for solid-liquid phase separation, forming larger polymer crystals. However, both the induced crystallization in NIPS, delayed phase separation and vapor induced solid-liquid phase separation in VIPS increase the crystallinity of the polymer, reduce the supersaturation degree of polymer crystal growth of the membrane material and the nucleation energy barrier in the crystallization process, easily cause rearrangement of molecular chain segments of the membrane material due to crystallization template effect, lead to enhancement of polymer micelle size discreteness, difficult regulation of molecular chain and micelle space uniformity, and cause problems of reduced membrane strength, nonuniform pore size and the like of the whole structure to a spherical particle stacking structure. Chinese patent CN113578062A proposes a preparation method of a durable hydrophilic uniform pore ultrafiltration membrane, which adopts a method of crosslinking and phase separation to improve the durable hydrophilicity of a membrane material on th