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Method for preparing high-intensity high-throughput polyvinylidene fluoride hollow fiber membrane

A polyvinylidene fluoride, high-throughput technology, used in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc. The effect of reducing the film pressure difference and operating energy consumption

Active Publication Date: 2009-05-27
NANJING LONGYUAN ENVIRONMENTAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the chemical modification technology is modified on the surface of the microporous membrane, it is easy to destroy the surface pore structure of the membrane, and change the molecular weight cut-off and filtration effect of the membrane.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] (1) Preparation of raw materials

[0026] 3kg of PVDF solid powder with a molecular weight of 1.5 million Daltons, 11.2L of solvent N,N'-dimethylacetamide, 1.5kg of porogen (polyvinylpyrrolidone, polyvinyl alcohol or polyethylene glycol), hydrophilic Modifier 1kg, core liquid is a mixture of ethanol and NMP with a weight ratio of 3:7.

[0027] (2) Preparation of hollow fiber membrane

[0028] Add PVDF solid powder to part of the solvent, stir to dissolve it, add dropwise sodium hydroxide solution, adjust the pH to 8-9, and form an active group; mix with a hydrophilic modifier, stir and react to obtain a hydrophilic polymer Vinylidene fluoride; gradually add it into the feed liquid tank containing the solvent, and the temperature of the solvent is 50°C. Stir while adding to make it dissolve evenly. After stirring for half an hour, add a porogen to the mixed solution, and continue stirring for 4 hours until the mixture is uniformly dissolved, then stop stirring to obta...

Embodiment 2—3

[0030] The hollow fiber membrane was prepared according to the same method and steps as in Example 1, except that the PVDF molecular weights of 500,000 and 1,000,000 Daltons were used in Embodiment 2 and Embodiment 3, respectively. The obtained hollow fiber membrane has a completely asymmetric structure, and its section is divided into two parts: an outer skin layer and a supporting layer, and the supporting layer has a honeycomb structure. The prepared hollow fiber membrane has an outer diameter of 1.5 mm, an inner diameter of 0.9 mm, a porosity of about 75%, and an average pore diameter of 0.03-0.05 μm.

Embodiment 4-6

[0032] The hollow fiber membrane was prepared according to the same method and steps as in Examples 1-3. The difference is that the molecular weights of PVDF used in Examples 4, 5, and 6 are 150,000, 500,000, and 1,000,000 Daltons, and the core fluid is a mixture of NMP and water at a weight ratio of 1:9.

[0033] The difference between the cross-section of the prepared hollow fiber membrane and the implementation example 1-3 is that the prepared membrane is a double skin layer, that is, the cross-sectional structure is divided into three parts: an outer skin layer, a support layer and an inner skin layer, and the support layer is a honeycomb structure. The prepared hollow fiber membrane has an outer diameter of 1.5 mm, an inner diameter of 0.9 mm, a porosity of about 75%, an average pore diameter of 0.03-0.05 μm, and tensile strengths of 1.3N, 2.1N and 2.8N, respectively.

[0034] It can be seen that the strength of the membrane made of low-molecular-weight raw material PVDF ...

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Abstract

The invention relates to a preparation method for a high-flux high-intensity polyvinylidene fluoride hollow fibrous membrane. In the method, 0.6 to 1.5 million daltons of polyvinylidene fluoride raw materials with super high molecular weight are chemically treated to lead the materials to form active groups and then are acted with hydrophilic compounds like glycidyl methacrylate or acrylic acid, and the like, to form a hydrophilic polyvinylidene fluoride raw material; the hydrophilic polyvinylidene fluoride material is mixed with a solvent and a pore-foaming agent according to a certain proportion to form membrane preparing liquid; then the membrane preparing liquid is woven into a uniformly distributed pollution-resistant polyvinylidene fluoride hollow fibrous membrane with high intensity, small aperture and high water flux by a phase inversion technique. The pollution-resistant polyvinylidene fluoride hollow fibrous membrane can be used for the fields like water processing, medicines, food, and industry by the forms of hyperfiltration, continuous micro-filter or membrane bioreactor according to the size of the millipore thereof.

Description

technical field [0001] The invention relates to a preparation method of a hollow fiber membrane, in particular to a preparation method of a high-strength and high-throughput polyvinylidene fluoride hollow fiber membrane suitable for use in the fields of microfiltration and ultrafiltration. Background technique [0002] At present, polymer membranes such as polyvinylidene fluoride (PVDF for short) have been widely used in the concentration, separation and purification processes in the production process of water purification, wine, fruit juice, medicine and other fields. This membrane separation technology has the advantages of simple operation, It has the advantages of less energy consumption, small footprint, and no secondary pollution, especially in water treatment. Unfortunately, these polymer membranes are mostly hydrophobic materials, and the membrane surface is easily polluted by organic matter in sewage, which reduces the water flux. Moreover, most of the existing pol...

Claims

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Application Information

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IPC IPC(8): B01D71/34B01D69/08
Inventor 徐忠任德胜
Owner NANJING LONGYUAN ENVIRONMENTAL CO LTD
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