Preparation method of modifying composite nanofiltration membrane by building pure COFs interlayer

A composite nanofiltration membrane and intermediate layer technology, applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc., can solve the problems of few interfacial polymerization processes, inability to fully infiltrate amine monomers, and low flux. Achieve excellent separation performance, achieve precise regulation, and high water flux

Inactive Publication Date: 2018-03-13
TIANJIN UNIV
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  • Abstract
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Problems solved by technology

[0005] However, there are relatively few reports on the effect of support layer on the interfacial polymerization process.
The interfacial polymerization method usually forms a separation layer on the basis of the ultrafiltration base membrane, but the commonly used ultrafiltration membrane has poor hydrophilicity and cannot fully infiltrate the amine monomer; the pore size distribution is not uniform, and the amine monomer is not evenly distributed during the interfacial polymerization process. , so that the separation layer is prone to defects; commonly used ultrafiltration membranes have low porosity, which is not conducive to the preparation of high-flux nanofiltration membranes
At the same time, the thickness of the separation layer of the nanofiltration membrane prepared by this method is generally above 100nm, and the flux is low.

Method used

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  • Preparation method of modifying composite nanofiltration membrane by building pure COFs interlayer
  • Preparation method of modifying composite nanofiltration membrane by building pure COFs interlayer

Examples

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Effect test

Embodiment 1

[0020] Embodiment 1, the preparation of pure COFs intermediate layer modified composite nanofiltration membrane, the steps are as follows:

[0021] Step 1. Preparation of TpPa-1 by Schiff base condensation: 0.3 mmol of 1,3,5-triformylphloroglucinol, 0.45 mmol of p-phenylenediamine, and 3 mL of 1,3 with a volume ratio of 1:1 , 5-trimethylbenzene / dioxane mixed solution, 0.5 mL of acetic acid aqueous solution with a concentration of 3 mol / L were placed in a heat-resistant flask, ultrasonicated for 2 min to obtain a mixed-phase suspension; and freeze-vacuum-thawed 3 times Cycle operation to room temperature. The freezing process is to place the flask in 77K liquid nitrogen to quickly freeze; after sealing, heat at 120 °C for three days to form a dark red precipitate and then collect by centrifugation; sequentially use acetone, tetrahydrofuran and dichloromethane to wash the precipitate, After collection, solvent exchange was performed in acetone, and then vacuum dried at 180 °C fo...

Embodiment 2

[0025] Example 2. Preparation of pure COFs interlayer modified composite nanofiltration membrane. The preparation process is basically the same as that in Example 1, except that: in the construction of the TpPa-1 interlayer in step 2, the deposition density of TpPa-1 was changed from 0.150 g / m 2 Change to 0.373g / m 2 , and finally obtained the pure COFs interlayer modified composite nanofiltration membrane, denoted as composite nanofiltration membrane 2.

[0026] The water flux of the composite nanofiltration membrane 2 prepared in Example 2 under the operating pressure of 0.2MPa is 82.770L / (m 2 h), for Na 2 SO 4 (mass fraction 0.1%), the retention rate was 89.02%, and the retention rate for the aqueous solution of orange yellow sodium (mass fraction 0.01%) was 92.52%. figure 1 Modified composite nanofiltration membrane 2 for pure COFs intermediate layer against Na 2 SO 4 (mass fraction of 0.1%), orange yellow sodium, Congo red, methyl blue and alcian blue (mass fraction ...

Embodiment 3

[0027] Example 3. Preparation of pure COFs interlayer modified composite nanofiltration membrane. The preparation process is basically the same as that in Example 1, except that in the construction of the TpPa-1 interlayer in step 2, the deposition density of TpPa-1 was changed from 0.150g to 0.150g. / m 2 Change to 0.448g / m 2 , and finally obtained the pure COFs interlayer modified composite nanofiltration membrane, which is denoted as composite nanofiltration membrane.

[0028] The water flux of the composite nanofiltration membrane 3 prepared in Example 3 under the operating pressure of 0.2MPa is 50.285L / (m 2 h), for Na 2 SO 4 (mass fraction 0.1%), the retention rate was 91.73%, and the retention rate for the aqueous solution of orange yellow sodium (mass fraction 0.01%) was 94.01%.

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Abstract

The invention discloses a method for preparing a modified composite nanofiltration membrane by constructing a pure COFs intermediate layer, which mainly includes: preparing TpPa-1 by using Schiff base condensation, constructing a pure COFs intermediate layer on a porous base membrane by vacuum filtration, and then A composite nanofiltration membrane is obtained through interfacial polymerization, wherein the porous base membrane is a polymer porous membrane with a pore diameter of 0.1 μm. In the present invention, by controlling the concentration of the aqueous phase monomer and the organic phase monomer in the interfacial polymerization step and the drying time after the interfacial polymerization reaction ends, the internal pore moisture and piperazine of the formed composite nanofiltration membrane can be effectively controlled. Molecules, that is, the hydrophilicity and porosity of the polyethersulfone-based membrane surface are optimized by vacuum filtration of the hydrophilic COFs intermediate layer, thereby realizing precise regulation of the interfacial polymerization process. The polyamide separation layer prepared by this method is thin and dense, Under the lower operating pressure (0.2MPa), it has higher water flux and maintains excellent separation performance.

Description

technical field [0001] The invention belongs to the technical field of preparation of composite membranes, and in particular relates to a preparation method of a composite nanofiltration membrane modified by constructing a pure COFs intermediate layer. Background technique [0002] Nanofiltration is a membrane process driven by a pressure difference. Nanofiltration membrane, as its core component, has nano-scale pore size, which can effectively retain natural organic matter, dyes and high-valent salt ions in water. And its operating pressure is low, it has the advantages of low energy consumption and easy to scale, and has been widely used in sewage treatment, seawater / brackish water desalination and other fields [0003] Interfacial polymerization is currently the most common and effective method for preparing commercial nanofiltration membranes, and has the advantages of simple operation and easy industrialization. The interfacial polymerization reaction is through the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D67/00B01D69/12B01D71/68
CPCB01D67/0006B01D69/125B01D71/68
Inventor 吴洪姜忠义吴梦园苏延磊杨昊曹利游昕达何雪溢贺明睿刘亚楠张润楠
Owner TIANJIN UNIV
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