Ionic liquid modified positively charged composite nanofiltration membrane and preparation method thereof

A composite nanofiltration membrane and ionic liquid technology, applied in the field of positively charged composite nanofiltration membrane and its preparation, can solve the problems of low permeation flux, poor film formation, poor compatibility between inorganic nanoparticles and polymer matrix, etc. To achieve the effect of simple process, easy industrial production, and industrial production

Active Publication Date: 2019-07-19
TSINGHUA UNIV
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Problems solved by technology

Chinese patent document (CN108636140A) proposes to use lactated chitosan as the water phase and polyacyl chloride as the organic phase interface polymerization to successfully prepare a positively charged nanofiltration membrane with good retention performance, but the permeation flux of the membrane is low
Chinese patent CN106925121A proposes interfacial polymerization of polyethylenimine modified by carbon nanotubes and polyacyl chlorides, and successfully prepares a positively charged composite nanofiltration membrane that can be used to extract lithium from salt lake brine with a high magnesium-to-lithium ratio. The poor compatibility of the particles with the polymer matrix leads to poor film-forming properties, making it difficult to realize industrial applications

Method used

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  • Ionic liquid modified positively charged composite nanofiltration membrane and preparation method thereof
  • Ionic liquid modified positively charged composite nanofiltration membrane and preparation method thereof
  • Ionic liquid modified positively charged composite nanofiltration membrane and preparation method thereof

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preparation example Construction

[0038] The present invention also provides a method for preparing a positively charged composite nanofiltration membrane, which specifically includes the following steps:

[0039] 1) Configure a polyamine aqueous phase solution with a certain mass volume concentration;

[0040] 2) Bottom film treatment: immerse the surface of the bottom film in the polyamine water phase solution, so that its surface is immersed in the polyamine water phase solution, and use a rubber roller to remove the excess water phase solution on the surface, and set aside;

[0041] 3) Interfacial polymerization reaction: configure a multi-component acid chloride organic phase solution with a certain mass volume concentration, pour the organic phase solution into the surface of the bottom film treated in step 2) to make it carry out interfacial polymerization reaction, and remove the organic phase solution on the bottom film surface after a certain period of time. Organic phase solution to prepare nascent ...

Embodiment 1～4

[0059] The preparation method of the positively charged composite nanofiltration membrane modified by amino functionalized ionic liquid comprises the following steps:

[0060] Pour the piperazine aqueous solution with a mass volume concentration of 0.5% on the surface of the fixed polyacrylonitrile base film and cover it, let it stand for 1 minute to allow the piperazine aqueous solution to soak into the surface of the base film, and remove the surface of the base film by rolling with a rubber roller The excess piperazine aqueous solution is dried for subsequent use; the mass volume concentration of 0.15% trimesoyl chloride / toluene solution is poured into the surface of the dried base film, and the organic solution on the surface is removed after the interface polymerization for 30 seconds; the mass volume concentration 0.5%, 1%, 1.5%, and 2% 1-aminopropyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt / dichloromethane solutions were poured into the bottom film afte...

Embodiment 5

[0069] The positively charged composite nanofiltration membrane was prepared in a manner basically similar to that of Example 1, but polyethersulfone was selected as the supporting bottom membrane, and amino functionalized ionic liquid organic solutions of different structures were used to modify the preparation. The organic solution is a 1.5% 1-aminoethyl-3-methylimidazolium bromide / ethanol solution, thereby preparing a modified positively charged composite nanofiltration membrane.

[0070] The nanofiltration membrane made above is carried out performance test of pure water flux and salt rejection rate, test result shows, the pure water flux of described charged nanofiltration membrane is 55.23L / (m2 h), for MgCl 2 The rejection rate of LiCl is 92.2%, the rejection rate of LiCl is 16.3%, and the separation factor of magnesium and lithium is 0.12.

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Abstract

The invention discloses an ionic liquid modified positively charged composite nanofiltration membrane and a preparation method thereof. The preparation method comprises the following steps: on a supporting bottom film, firstly, carrying out interfacial polymerization on polyamine and polyacyl chloride to form a primary polyamide layer, and then carrying out an amidation reaction on acyl chloride groups remaining on the surface of the primary polyamide layer and amino functionalized ionic liquid to prepare the composite film. The preparation method comprises the following steps: (1) preparing apolyamine aqueous phase solution and a polyacyl chloride organic phase solution; (2) carrying out interfacial polymerization on the surface of the bottom film to prepare a primary polyamide nanofiltration membrane; and (3) reacting the amino-functionalized ionic liquid solution with acyl chloride groups on the surface of the primary polyamide layer, and carrying out heat treatment to obtain the positively charged composite nanofiltration membrane. By changing the charge property of the composite membrane, lithium resources in the salt lake brine with a high magnesium-lithium ratio can be effectively extracted, the magnesium-lithium separation factor of the composite membrane is lower than 0.15, and the flux is 40-50L/m<2>h. The method has the advantages that the preparation method is simple, and the method has a good industrial application prospect in the aspect of salt lake lithium extraction.

Description

technical field [0001] The invention relates to a positively charged composite nanofiltration membrane modified by ionic liquid and a preparation method thereof, and belongs to the technical field of membrane material preparation and membrane separation. Background technique [0002] With the rapid development of new energy fields such as mobile phones, notebook computers, electric vehicles and other industries, the market demand for lithium resources has increased sharply. How to effectively develop metal lithium, lithium salts and other products is particularly important. Lithium resources mainly exist in ore, salt lake brine and seawater, and 70% of my country's lithium resource content is stored in salt lake brine, but the amount of lithium extracted from salt lake brine only accounts for 8% of the total extraction. The main reason is that the ratio of magnesium to lithium in my country's salt lake brine is high, and the difficulty in separating magnesium and lithium lea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D69/12B01D69/02B01D67/00B01D71/56
CPCB01D67/0006B01D69/02B01D69/125B01D71/56B01D2325/16
Inventor 王晓琳吴欢欢汪林
Owner TSINGHUA UNIV
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