Nano-filtration membrane, preparation method and applications of thereof

A nanofiltration membrane and composite membrane technology, applied in the field of nanofiltration membranes, can solve the problem that the retention rate of divalent ions is only 98%, and achieve the effects of increasing the crosslinking density, increasing the salt rejection rate, and improving the degree of crosslinking.

Active Publication Date: 2019-04-30
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This type of composite membrane has good water permeability, but the rejection rate of divalent ions is only about 98%.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0040] The present invention also provides the preparation method of above-mentioned nanofiltration membrane, and this method comprises the following steps:

[0041] (1) forming a polyamide separation layer on one surface of the support layer to obtain a composite membrane;

[0042] (2) first contacting the composite film obtained in step (1) with the polyphenolic compound, so that the polyhydric phenolic compound and the polyamide undergo a crosslinking reaction;

[0043] (3) second contacting the composite membrane obtained in step (2) with polyvalent metal cations to chelate the polyvalent metal cations with polyhydric phenolic compounds.

[0044] In the method of the present invention, the support layer is not particularly limited, it can be made of various existing materials with certain strength and can be used for nanofiltration membranes, usually polyester, polyacrylonitrile , polyvinylidene fluoride, phenolphthalein type non-sulfonated polyarylethersulfone, polyether...

Embodiment 1

[0083] The nanofiltration membrane M1 prepared according to the method of Comparative Example 1 was immersed in an aqueous solution containing 1% by weight of tannic acid, the temperature of the immersion solution was 25° C., and the immersion time was 1 min. After taking it out, wash it with deionized water. The membrane was then immersed in 1 wt% MgSO 4 In the aqueous solution, the immersion temperature is 25°C, and the immersion time is 5min. After taking it out, wash it with deionized water. Put the diaphragm into the cross-flow membrane tank, and under 0.2Mpa, use deionized water as the medium, pre-press for 120min, and obtain the nanofiltration membrane N1 with a surface modified membrane formed on the surface of the polyamide separation layer, wherein the surface modification The thickness of the permanent film is 0.060 μm.

Embodiment 2

[0085] The nanofiltration membrane M1 prepared according to the method of Comparative Example 1 was soaked in an aqueous solution containing 5% by weight of tannic acid, the temperature of the soaking solution was 25° C., and the soaking time was 5 minutes. After taking it out, wash it with deionized water. The membrane was then immersed in 2 wt% MgSO 4 In the aqueous solution, the immersion temperature is 25°C, and the immersion time is 30s. After taking it out, wash it with deionized water. Put the diaphragm into the cross-flow membrane tank, under 0.1Mpa, use deionized water as the medium, pre-press for 120min, and obtain the nanofiltration membrane N2 with the surface modified membrane formed on the surface of the polyamide separation layer, wherein the surface modification The thickness of the permanent film is 0.064 μm.

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Abstract

The invention relates to the field of separation membranes, particularly to a nano-filtration membrane and a preparation method thereof, and applications of the nano-filtration membrane in water treatment processes. The nano-filtration membrane comprises a support layer and a polyamide separation layer, wherein one surface of the polyamide separation layer is attached to the support layer, the other surface of the polyamide separation layer is cross-linked with a polyphenol-based compound, and the polyphenol-based compound is chelated with polyvalent metal cations. According to the present invention, tannic acid reacts with the residual amino group in the polyamide separation layer so as to increase the cross-linking density of the polyamide surface, and the cross-linking degree of the membrane surface is further increased through the chelating action between the polyvalent metal cations and the tannic acid, such that the salt retention rate of the membrane is significantly increased.

Description

technical field [0001] The invention relates to the field of separation membranes, in particular to a nanofiltration membrane, a preparation method of the nanofiltration membrane and an application of the nanofiltration membrane in a water treatment process. Background technique [0002] Membrane separation technology is a new separation technology that appeared in the early 20th century and rose rapidly after the 1960s. Because membrane separation technology not only has the functions of separation, concentration, purification and refining, but also has the characteristics of high efficiency, energy saving, environmental protection, molecular level filtration, simple filtration process and easy control, it is widely used in food, medicine, biology, environmental protection, chemical industry , metallurgy, energy, petroleum, water treatment, electronics, bionics and other fields, and has produced huge economic and social benefits, and has become one of the most important mea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/56B01D69/10B01D69/12B01D61/02C02F1/44
CPCB01D61/027B01D69/10B01D69/125B01D71/56C02F1/442B01D2323/30
Inventor 张杨徐健刘轶群潘国元严昊
Owner CHINA PETROLEUM & CHEM CORP
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