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Preparation method of polyvinyl alcohol composite nano-filtration membrane

A technology of polyvinyl alcohol and nanofiltration membrane, which is applied in the field of membrane separation and can solve the problems of water permeability reduction and other issues

Inactive Publication Date: 2018-06-15
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Chemical cross-linking modification increases the water resistance and mechanical strength of PVA, but at the same time reduces the water permeability of the membrane

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0010] Mix ethanol and pure water in a volume ratio of 1:1 to form a solvent, add 1,3,5-benzenetricarboxylic acid and sodium dodecylsulfonate, and the mass volume ratio of it to the solvent is 0.2% and 0.15%, respectively, Stir and dissolve at room temperature to make a cross-linking agent solution; dissolve polyvinyl alcohol in pure water with a mass volume ratio of 0.1%, heat and stir at 95°C for 1.5 hours to make an aqueous solution, place it at room temperature and add a small amount of concentrated H 2 SO 4 . Apply the cross-linking agent solution on the polysulfone base film in a predetermined amount by slit coating, the coating amount is 15 g / m2, put it in an oven at 25 °C and dry it; then continue to coat the surface of the film through the slit A predetermined amount of 0.1% polyvinyl alcohol aqueous solution is coated on cloth, the coating amount is 25 g / m2, and it is baked at 80° C. for 10 minutes to form a film. The thickness of the membrane cortex was analyzed b...

Embodiment 2-3

[0013] The mass fraction of 1,3,5-benzenetricarboxylic acid in the crosslinking agent solution was changed, and other steps were performed in the same manner as in Example 1 to prepare a composite membrane and test it. The results are shown in the following table:

[0014] 1,3,5-Benzenetricarboxylic acid / wt%

Embodiment 4-5

[0016] The mass fraction of the polyvinyl alcohol aqueous solution was changed, the mass fraction of 1,3,5-benzenetricarboxylic acid was 0.2%, the other steps were the same as in Example 1, and the composite film was prepared and tested, and the results were obtained in the following table:

[0017] PVA wt%

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Abstract

The invention discloses a preparation method of a polyvinyl alcohol nano-filtration membrane. The preparation method comprises the following steps of: mixing ethanol and pure water according to a volume ratio of 1:1, adding a certain amount of 1,3,5-benzene tricarbonic acid and sodium dodecyl sulfate, and carrying out stirring for dissolution at a normal temperature to prepare a cross-linking agent solution; dissolving polyvinyl alcohol in pure water, carrying out heating and stirring at 95 DEG C for 1.5 hours to prepare an aqueous solution, and dropwise adding concentrated H2SO4 for later use; coating a predetermined amount of the cross-linking agent solution on a polysulfone base membrane by slit coating; and coating a predetermined amount of the polyvinyl alcohol aqueous solution on thesurface of the membrane by slit coating, and carrying out drying in an oven at a certain temperature to obtain a membrane, thereby forming an ultra-thin skin layer with a uniform thickness of 40-80 nanometers. According to the preparation method provided by the invention, the cross-linking agent with hydrophilic groups is selected to form a gradient cross-linked structure with gradually decreasing cross-linking degrees from bottom to top, so that the water flux can be greatly improved. Moreover, the wettability of the base membrane can be obviously improved, which is helpful for PVA to be uniformly and firmly attached to the base membrane.

Description

technical field [0001] The invention belongs to the technical field of membrane separation, and in particular relates to a preparation method of a polyvinyl alcohol nanofiltration membrane, especially a preparation method of a polyvinyl alcohol nanofiltration membrane with high flux under low pressure. Background technique [0002] Polyvinyl alcohol (PVA) is a white granular polymer substance with a large number of hydroxyl groups on the molecular chain, which can react with a cross-linking agent to form a macromolecular network structure; PVA molecules have good water solubility and film-forming properties However, the pure PVA membrane is very easy to swell in water, has high permeability to water and solute at the same time, and cannot separate the solute, so it needs to be modified to improve its water resistance. Therefore, people have carried out a lot of research on the modification of PVA composite membranes, such as using chemical cross-linking methods, using substa...

Claims

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Application Information

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IPC IPC(8): B01D69/12B01D69/02B01D67/00B01D71/38
CPCB01D67/0002B01D67/0006B01D69/02B01D69/12B01D69/125B01D71/38B01D2323/02B01D2325/36
Inventor 周勇郭淼高从堦
Owner ZHEJIANG UNIV OF TECH
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