Super hydrophobic modification method for polyvinylidene fluoride hydrophobic membranes

A polyvinylidene fluoride and hydrophobic membrane technology, which is applied in the field of separation membranes, can solve the problem of low hydrophobicity on the surface of PVDF microporous membranes, and achieve the effects of low cost, high desalination rate, and short process

Inactive Publication Date: 2011-09-14
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0020] The primary purpose of the present invention is to solve the problem that the surface hydrophobicity of the existing PVDF microporous membrane is not high, and to provide a metho

Method used

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  • Super hydrophobic modification method for polyvinylidene fluoride hydrophobic membranes
  • Super hydrophobic modification method for polyvinylidene fluoride hydrophobic membranes
  • Super hydrophobic modification method for polyvinylidene fluoride hydrophobic membranes

Examples

Experimental program
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Effect test

Embodiment 1

[0051] 1. Mix PVDF (7%), DMAC (56%) and 1,2-propanediol (40%), stir on a magnetic stirrer with heating for 6 to 7 hours, and control the temperature of the membrane liquid at 75°C, Obtain a clear and uniform casting solution, and then put the film solution in an oven at 60°C for 24 hours to fully mature and defoam, and then use it as the upper layer of the film solution;

[0052] 2. Mix PVDF (20%), DMAC (77%) and LiCl (3%), stir on a heated magnetic stirrer for 6-7 hours, and control the temperature of the film liquid at 75°C to obtain a clear and uniform cast film solution, and then put the membrane solution in an oven at 60°C for 48 hours to fully mature and defoam, and then use it as the lower layer membrane solution;

[0053] 3. Scrape the 75°C lower layer liquid film obtained in step 2 on a glass plate to form a 0.15mm thick lower layer liquid film, and at the same time scrape the 60°C film liquid in step 1 into an upper layer film liquid with a thickness of 0.04-0.05mm, ...

Embodiment 2

[0057] 1. Mix PVDF (4%), DMAC (66%) and ethylene glycol (30%), stir on a magnetic stirrer with heating for 6 to 7 hours, and control the temperature of the membrane liquid at 60°C to obtain clarification Uniform casting solution, and then put the film solution in an oven at 60°C for 48 hours to fully mature and defoam, and use it as the upper layer of film solution;

[0058]2. Mix PVDF (20%), DMAC (76%) and LiCl (4%), stir on a magnetic stirrer with heating for 6-7 hours, control the temperature of the membrane liquid at 60°C, and obtain a clear and uniform Cast the film solution, and then put the film solution in an oven at 60°C for 36 hours to fully mature and defoam, and then use it as the lower layer film solution;

[0059] 3. Scrape the 60°C film liquid obtained in step 2 on the glass plate to form a lower liquid film with a thickness of 0.16mm, and at the same time scrape the 60°C film liquid in step 1 to form an upper film liquid with a thickness of 0.04mm, and immediat...

Embodiment 3

[0063] 1. Mix PVDF (10%), DMAC (60%) and 1,2-propylene glycol (35%), stir on a magnetic stirrer with heating for 6 to 7 hours, so that the temperature of the membrane liquid is controlled at 60°C, Obtain a clear and uniform casting solution, and then place the film solution in an oven at 60°C for 36 hours to fully mature and defoam, and then use it as the upper layer of the film solution;

[0064] 2. Mix PVDF (20%), DMAC (78%) and LiCl (2%), stir on a magnetic stirrer with heating for 6 to 7 hours, and control the temperature of the membrane liquid at 60°C to obtain a clear and uniform Cast the film solution, and then put the film solution in an oven at 60°C for 24 hours to fully mature and defoam, and then use it as the lower layer film solution;

[0065] 3. Scrape the 60°C film liquid obtained in step 2 on the glass plate to form a lower liquid film with a thickness of 0.16 mm, and at the same time scrape the 60°C film liquid in step 1 to form an upper film liquid with a thi...

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Abstract

The invention discloses a super hydrophobic modification method for polyvinylidene fluoride hydrophobic membranes and belongs to the technical field of membrane separation. The method comprises: preparing membrane casting solution by using polyvinylidene fluoride (PVDF), N,N-dimethylacetamide (DMAC) serving as a solvent and non-solvent low-molecular-weight alcohol and aging the membrane casting solution to form upper membrane solution; preparing membrane casting solution by using PVDF, DMAC, LiCl or/and polyvinyl pyrrolidone (PVP), and aging the membrane casting solution to form lower membrane solution, wherein the PVDF content in the lower membrane solution is higher than that in the upper membrane solution; scraping the lower membrane solution and the upper membrane solution on a glass plate in turn, and placing the glass plate in air at 50 to 75 DEG C and at a water relative humidity of 80 to 100 percent to obtain a primary ecological membrane; and immersing in running water for stripping the membrane and drying to obtain a polyvinylidene fluoride composite film of which the surface is super hydrophobic. In the invention, the method is simple, the process flow is short, the cost is low, and the prepared membrane has high flux and high salt rejection rate.

Description

technical field [0001] The invention belongs to the technical field of separation membranes, and in particular relates to a superhydrophobic modification method on the surface of a polyvinylidene fluoride membrane. Background technique [0002] One of the main reasons why membrane distillation has not been applied in large-scale industry at present is that the permeation flux of the membrane used for membrane distillation is low, and it is not competitive compared with other separation technologies. The other is the wetting of the membrane pores during operation, and the flux is not stable enough. Therefore, the requirement for the membrane used in membrane distillation is to obtain stable high flux. Mohamed Khayet [Khayet M.Membranes and theoretical modeling of membranedistillation, A review, Adv Colloid Interface Sci.2010] concluded that such a membrane should meet the following requirements: [0003] 1. Single-layer or multi-layer structure, but at least one layer is a ...

Claims

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Application Information

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IPC IPC(8): B01D71/34B01D67/00B01D69/10B01D69/12
Inventor 彭跃莲范红玮
Owner BEIJING UNIV OF TECH
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