CN-122006521-A - Polyamide nanofiltration membrane regulated and controlled by tannic acid coordination ZIF-8 intermediate layer, and preparation method and application thereof

Abstract

A tannic acid coordination ZIF-8 interlayer regulated polyamide nanofiltration membrane, a preparation method and application thereof relate to the technical field of polyamide nanofiltration membrane preparation and comprise a polyacrylonitrile supporting layer, wherein the surface of the polyacrylonitrile supporting layer is provided with an interlayer formed by mixing piperazine and TA/ZIF-8 nano particles, the surface of the interlayer, which is away from the polyacrylonitrile supporting layer, is distributed with a selective layer which is formed by the interface reaction of an oil phase solution and the interlayer and is in an integral structure with the interlayer.

Inventors

• LI RUI
• ZHANG FANG
• LI LINZE
• DONG CHENGYU
• LI JIAHAO
• LI ZHEXIN
• GAO JIAYU
• HE MENG
• LI ZUYU
• TU QIRUI
• LI YANQIANG
• Han Shuangqiao
• CHEN PINGPING

Assignees

• 华北水利水电大学

Dates

Publication Date

20260512

Application Date

20260327

Claims (10)

1. 1. A polyamide nanofiltration membrane regulated and controlled by a tannic acid coordination ZIF-8 middle layer comprises a polyacrylonitrile supporting layer and is characterized in that the surface of the polyacrylonitrile supporting layer is provided with a middle layer formed by mixing piperazine and TA/ZIF-8 nano particles, and the surface of the middle layer, which faces away from the polyacrylonitrile supporting layer, is distributed with a selection layer which is formed by the reaction of an oil phase solution and a middle layer interface and is in an integral structure with the middle layer.
2. 2. A polyamide nanofiltration membrane regulated and controlled by a tannic acid coordination ZIF-8 intermediate layer is characterized in that the surface load of TA/ZIF-8 nano particles on the surface of a polyacrylonitrile supporting layer is 4.8-12.0 mug/cm 2 .
3. 3. A polyamide nanofiltration membrane regulated and controlled by a tannic acid coordination ZIF-8 intermediate layer is characterized in that the thickness of a selected layer is 50-120 nm.
4. 4. A preparation method of a polyamide nanofiltration membrane regulated and controlled by a tannic acid coordination ZIF-8 intermediate layer is characterized in that ZIF-8 nano particles and tannic acid are in contact reaction in an ethanol system to obtain TA/ZIF-8 nano particles, the TA/ZIF-8 nano particles are dispersed in a water phase solution containing piperazine and deposited on the surface of a polyacrylonitrile supporting layer through vacuum filtration to form the intermediate layer on the surface of the polyacrylonitrile supporting layer, the oil phase solution is added on the surface of the intermediate layer to carry out interfacial polymerization, and then the temperature is 50-80 ℃ and the temperature is heated for 5-30 minutes to obtain the polyamide nanofiltration membrane.
5. 5. The method for preparing the polyamide nanofiltration membrane regulated and controlled by the tannic acid coordination ZIF-8 interlayer, as set forth in claim 4, is characterized in that the preparation method of the ZIF-8 nanoparticles comprises the steps of dissolving zinc nitrate hexahydrate in methanol solution to form zinc nitrate methanol solution with the concentration of 10-15 mg/mL, dissolving 2-methylimidazole in the methanol solution to form 2-methylimidazole methanol solution with the concentration of 10.0-16.0 mg/mL, mixing the zinc nitrate methanol solution and the 2-methylimidazole methanol solution in a volume ratio of 1:0.8-1.2, stirring, aging for 24 hours at 25 ℃, centrifuging to obtain precipitate, washing the precipitate, and vacuum drying at 60 ℃ to obtain the ZIF-8 nanoparticles.
6. 6. The method for preparing the polyamide nanofiltration membrane regulated and controlled by the tannic acid coordination ZIF-8 interlayer, as claimed in claim 4, is characterized in that ZIF-8 nanoparticles and tannic acid are subjected to contact reaction in an ethanol system, the method for obtaining TA/ZIF-8 nanoparticles is that ZIF-8 nanoparticles are dispersed in ethanol at a ratio of 1.0-3.0 mg to 1mL to form a dispersion liquid, tannic acid is dissolved in ethanol to form a mixed solution with a concentration of 1.0-3.0 mg/mL, the mixed solution and the dispersion liquid are mixed at a volume ratio of 1:0.8-1.2, and then are subjected to magnetic stirring, centrifugal separation, washing and vacuum drying at 60 ℃ for 12 hours to obtain TA/ZIF-8 nanoparticles.
7. 7. The method for preparing the tannic acid coordination ZIF-8 interlayer-regulated polyamide nanofiltration membrane as claimed in claim 4, wherein the ratio of TA/ZIF-8 nanoparticles to the aqueous phase solution containing piperazine is 0.005-0.03 mg/1 mL.
8. 8. The method for preparing a tannic acid coordination ZIF-8 interlayer-regulated polyamide nanofiltration membrane as claimed in claim 4, wherein the piperazine concentration in the aqueous phase solution containing piperazine is 0.2wt%.
9. 9. The method for preparing the polyamide nanofiltration membrane regulated and controlled by the interlayer of the tannic acid coordination ZIF-8, as claimed in claim 4, wherein the oil phase solution is trimesoyl chloride-n-hexane solution.
10. 10. Use of a polyamide nanofiltration membrane obtained by the process of any one of claims 4 to 9 in brine separation, ion screening or monovalent/divalent silver ion selective separation.

Description

Polyamide nanofiltration membrane regulated and controlled by tannic acid coordination ZIF-8 intermediate layer, and preparation method and application thereof Technical Field The invention relates to the technical field of preparation of polyamide nanofiltration membranes, in particular to a tannic acid coordination ZIF-8 intermediate layer regulated polyamide nanofiltration membrane, a preparation method and application thereof. Background The nanofiltration membrane has high water flux and good selective interception capability to multivalent ions and small organic molecules, and has wide application prospects in the fields of brackish water, industrial wastewater treatment, resource separation, high-salt system selective salt separation and the like. At present, an interfacial polymerization method is mostly adopted for nanofiltration membranes, specifically, a polyamide selection layer is formed on the surface of a porous support membrane, so that a thin film composite nanofiltration membrane is prepared. Although the membrane has better separation performance, the diffusion process of the aqueous phase monomer is difficult to control accurately due to the high interfacial polymerization reaction speed, the obtained polyamide layer is generally compact, and the restriction relationship between the flux and the selectivity of the membrane is easy to exist. In the prior art, the interfacial polymerization process is regulated and controlled by constructing an intermediate layer to improve the structure and performance of the traditional polyamide nanofiltration membrane, for example, patent CN113663530A discloses a polyamide ceramic composite nanofiltration membrane containing a MoS 2 intermediate layer and a preparation method thereof, the intermediate layer of MoS 2 is constructed on the surface of a ceramic matrix and then subjected to interfacial polymerization to promote the formation of a continuous and uniform polyamide separation layer, and patent CN115845639A discloses a nanofiltration membrane containing a molecular sieve organic composite material intermediate layer and a preparation method thereof, and the intermediate layer is formed by suction filtration and then subjected to interfacial polymerization to improve the desalination performance of the nanofiltration membrane. In the prior art, there are also schemes for improving the comprehensive performance of nanofiltration membranes by introducing nano materials, for example, patent CN105080367B discloses a composite nanofiltration membrane containing composite nano particles and a preparation method, the composite nano particles are added into an organic phase to disperse the nano particles in a functional layer so as to improve the comprehensive performance of the membrane, patent CN115090123a discloses a nanofiltration membrane preparation based on a positively charged nano material intermediate layer and application thereof, and the positively charged nano material is subjected to vacuum filtration to be compounded on the surface of a porous carrier membrane to form a double-layer composite membrane, and then interfacial polymerization is carried out to improve the permeation and separation performance of the membrane. However, the two schemes still have the following defects that 1) the prior scheme often disperses nano-particles such as nano-cages or modified metal organic frameworks in an organic phase. This conventional approach does not allow a direct and precise confinement of the aqueous monomer diffusion behaviour, which is very likely to lead to random embedment or even agglomeration of the nanoparticles in the polyamide layer, thus introducing non-selective defects. Secondly, a significant diffusion coefficient gradient is difficult to construct at an organic-water interface by simple organic phase dispersion, and deep remodeling of the thickness, the crosslinking degree and the surface micro morphology of the polyamide layer is difficult to realize, so that the traditional nanofiltration membrane is difficult to break through the restriction effect of the difference between flux and selectivity. Thirdly, the synchronous improvement of the performances such as high-selectivity separation, pollution resistance and long-term stable operation of monovalent/divalent ions still has the defects. Disclosure of Invention The invention aims to provide a polyamide nanofiltration membrane regulated and controlled by a tannic acid coordination ZIF-8 interlayer, a preparation method and application thereof, which are used for improving the dispersibility and interfacial compatibility of nanoparticles in an interfacial polymerization process, reducing the thickness of a polyamide layer, simultaneously taking the membrane flux and the selectivity into consideration, and improving the pollution resistance and the long-term stability of the polyamide nanofiltration membrane. In order to achieve the aim, the specific scheme adopted by the inve