Search

CN-122006506-A - Method for preparing super-hydrophobic membrane by silane-assisted non-solvent induced phase separation, super-hydrophobic membrane and application

CN122006506ACN 122006506 ACN122006506 ACN 122006506ACN-122006506-A

Abstract

The invention belongs to the technical field of membrane separation, and discloses a method for preparing a super-hydrophobic membrane by silane-assisted non-solvent induced phase separation, the super-hydrophobic membrane and application thereof. The silane molecular layer delays the phase separation rate, a fiber-connected open pore Gao Cucao structure is constructed on the surface of the membrane, and long-chain siloxane entangled with the polymer is formed at the same time, so that the synchronous improvement of hydrophobicity and stability is realized. The method is simple to operate and mild in condition, the contact angle of the obtained membrane water is more than 150 degrees, the tensile strength is more than 3.4 MPa, the liquid permeation pressure is more than 276 kPa, and the method is suitable for the fields of membrane distillation and the like.

Inventors

  • WU CHUNRUI
  • GAO HAIFU
  • HE LONGFEI
  • SONG ZIPING
  • 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 method for preparing a super-hydrophobic membrane by silane-assisted non-solvent induced phase separation is characterized by comprising the following steps: (1) Mixing a polymer film material, a solvent and a pore-forming agent, stirring at constant temperature for dissolution to obtain uniform film casting liquid, and scraping the film casting liquid into a nascent liquid film; (2) The method comprises the steps of utilizing silane molecules to spray and modify a nascent liquid film to form the nascent liquid film with a silane molecular layer on the surface, wherein the silane molecules comprise one or more of dimethyl dimethoxy silane, ethyl trimethoxy silane, methyl triethoxy silane, 3-trifluoro propyl methyl dimethoxy silane, 1H, 2H-perfluoro octyl methyl dimethoxy silane; (3) And immersing the nascent liquid film with the surface being a silane molecular layer in a coagulating bath for phase separation and solidification to obtain the super-hydrophobic film.
  2. 2. The method of claim 1, wherein the polymer film material comprises one or more of polyvinylidene fluoride, polyvinyl chloride, polyvinylidene fluoride-hexafluoropropylene, and polyvinylidene fluoride-chlorotrifluoroethylene.
  3. 3. The method according to claim 1, wherein the solvent comprises one or more of dimethylacetamide, dihydrol-glucosone, dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.
  4. 4. The method of claim 1, wherein the porogen comprises one or more of water, ethanol, methanol, isopropanol, propylene glycol, and n-butanol.
  5. 5. The method of claim 1, wherein the casting solution comprises 11wt% to 20wt% of the polymer film material, 55wt% to 80wt% of the solvent, and 9wt% to 25wt% of the porogen, based on 100wt% of the total mass.
  6. 6. The method of claim 1, wherein the silane molecules are spray modified for a period of 20s to 200s and a spray flow rate of 100 to 400mL/h.
  7. 7. The method according to claim 1, wherein the constant temperature stirring dissolution temperature is 60-90 ℃ for 4-12 hours.
  8. 8. The method of claim 1, wherein the coagulation bath is a deionized water solution and the coagulation bath temperature is 20-70 ℃.
  9. 9. A superhydrophobic film according to any one of claims 1-8, wherein the surface of the film has a reinforced network structure of low surface energy long chain siloxanes intertwined with polymer molecular chains and exhibits a fiber-linked open pore Gao Cucao structure.
  10. 10. Use of the superhydrophobic film of claim 9 in the preparation of a film distillation device, a film deamination device or a pervaporation film device.

Description

Method for preparing super-hydrophobic membrane by silane-assisted non-solvent induced phase separation, super-hydrophobic membrane and application Technical Field The invention belongs to the technical field of membrane separation, and relates to a method for preparing a super-hydrophobic membrane by silane-assisted non-solvent induced phase separation, the super-hydrophobic membrane and application. Background The contradiction between the increase of industrial and agricultural water demand and the relatively lagging development of advanced wastewater treatment technology leads to serious problems of water pollution and fresh water shortage. But is key to solving the problem of desalination of seawater and brackish water and resource utilization of wastewater. Membrane distillation technology with hydrophobic microporous membrane as the core has become a research hotspot in the water treatment industry due to its low-grade energy utilization capacity, nearly 100% desalination capacity and relatively mild operating conditions. The pollution wetting problem faced by the hydrophobic membrane is always the main problem faced in the application and popularization processes. The traditional hydrophobic membrane materials used for membrane distillation mainly comprise polytetrafluoroethylene, polypropylene, polyvinylidene fluoride and the like. Among them, polyvinylidene fluoride has been attracting attention due to its good chemical stability, film forming property and moderate cost. However, PVDF membranes prepared by conventional non-solvent induced phase separation methods tend to have insufficient surface hydrophobicity (water contact angles typically between 90 ° -120 °) and membrane pores are easily wetted by surfactants or low surface tension substances when exposed to complex feed solutions for long periods of time, resulting in dramatic drop in rejection rate and even process failure. In order to improve the hydrophobicity and the anti-wetting capability of the membrane, researchers at home and abroad mainly follow two basic principles, namely, constructing a micro/nano level coarse structure to increase the surface hydrophobicity and introducing a low surface energy substance to reduce the surface free energy. Currently, the main current technical means can be divided into the following four types: (1) The surface post-modification method is to prepare a base film with a porous structure, and load hydrophobic nano particles (such as silicon dioxide and titanium dioxide) or modify low-surface energy substances (such as fluorosilane) on the surface of the film by spray coating, dip coating, graft polymerization or chemical vapor deposition. For example, the prior art discloses dispersing fluorinated modified nano-silica particles in ethanol and depositing the particles on the surface of a formed PVDF-based film by spraying to obtain a superhydrophobic coating. Although the contact angle can be obviously improved by the method, most of the introduced hydrophobic layers and the base film are in physical adsorption or weakening combination, and the hydrophobic layers and the base film are easy to fall off and peel off under the conditions of long-term hydraulic flushing, high temperature or strong acid and alkali, so that the performance is attenuated and the stability is insufficient. And the post-treatment steps are complicated, so that the production cost and time are increased. (2) The blending modification method is that hydrophobic nano filler (such as carbon nano tube, graphene, organic metal frame material or modified inorganic nano particles) is directly blended with polymer in casting film liquid, and part of the polymer is exposed on the surface of the film or distributed in the film body through the phase inversion process, so that the hydrophobicity and other properties of the film are improved. However, the dispersibility of nanofillers and their interfacial compatibility with polymers are a technical difficulty. The filler is easy to agglomerate, which not only affects the uniformity of the membrane structure, but also can block part of pore channels, resulting in flux reduction. More importantly, blending modification has limited fine regulation and control capability on the micro-morphology of the film surface, and an ideal high-roughness structure is difficult to construct directionally. (3) The method does not depend on additional filler, but directly builds a rough film surface by regulating thermodynamic and kinetic processes of phase separation. Among them, steam-induced phase separation is one of representative techniques. The method is to put the scraped nascent liquid film in a high humidity environment for standing for a period of time, so that water vapor in the air slowly permeates into the film surface to induce the polymer to slowly phase separate, thereby forming a unique surface pore structure. There have been reports in the prior art of rapid construction of superhydrophob