阅读说明：本技术 一种中空纳米颗粒复合纳滤膜及其制备方法和用途 (Hollow nano-particle composite nanofiltration membrane and preparation method and application thereof ) 是由 张国亮 李洋 于 2019-08-29 设计创作，主要内容包括：本发明公开了一种中空纳米颗粒复合纳滤膜及其制备方法和用途,所述的制备方法为：将浓度为1～10mg/mL的单宁酸水溶液与浓度为0.5～20mg/mL的纳米颗粒水溶液混合,搅拌反应后离心分离,得到沉淀物去除杂质,得到刻蚀好的中空纳米颗粒加入到质量分数为0.05％～5％的哌嗪的水溶液中得到混合液,然后将所述的混合液均匀铺在聚合物底膜的表面,保持30～180s后吸干所述聚合物底膜表面的水,然后将质量分数为0.01％～1％的均苯三甲酰氯的正己烷溶液均匀铺在所述混合液处理过的聚合物底膜表面,反应15～150s,去除表面多余的溶剂,静置后干燥,即得中空纳米颗粒复合纳滤膜。本发明所述的中空纳米颗粒复合纳滤膜应用于盐类的分离。本发明提高了膜的亲水性,显著提高了水通量,且膜制备过程简单。(The invention discloses a hollow nano-particle composite nanofiltration membrane as well as a preparation method and application thereof, wherein the preparation method comprises the following steps: mixing a tannic acid aqueous solution with the concentration of 1-10 mg/mL and a nano-particle aqueous solution with the concentration of 0.5-20 mg/mL, stirring for reaction, performing centrifugal separation to obtain a precipitate, removing impurities, adding etched hollow nano-particles into a piperazine aqueous solution with the mass fraction of 0.05-5% to obtain a mixed solution, uniformly paving the mixed solution on the surface of a polymer base membrane, keeping the mixed solution for 30-180 s, sucking water on the surface of the polymer base membrane, uniformly paving an n-hexane solution of trimesoyl chloride with the mass fraction of 0.01-1% on the surface of the polymer base membrane treated by the mixed solution, reacting for 15-150 s, removing redundant solvent on the surface, standing, and drying to obtain the hollow nano-particle composite nanofiltration membrane. The hollow nano-particle composite nanofiltration membrane is applied to salt separation. The invention improves the hydrophilicity of the membrane, obviously improves the water flux and has simple membrane preparation process.)

1. A hollow nano particle composite nanofiltration membrane is characterized in that: the hollow nano-particle composite nanofiltration membrane is prepared by the following method:

(1) Mixing 1-10 mg/mL tannic acid aqueous solution with 0.5-20 mg/mL nano-particle aqueous solution, stirring for reaction for 3-120 min, then carrying out centrifugal separation, washing the obtained precipitate with methanol and water to remove impurities, and obtaining etched hollow nano-particles; the volume ratio of the tannic acid aqueous solution to the nano-particle aqueous solution is 0.4-2;

(2) Adding the etched hollow nano particles obtained in the step (1) into a piperazine water solution with the mass fraction of 0.05% -5% to obtain a mixed solution, uniformly coating the mixed solution on the surface of a polymer base membrane, keeping the mixed solution for 30-180 s, then sucking water on the surface of the polymer base membrane, uniformly paving a n-hexane solution of trimesoyl chloride with the mass fraction of 0.01% -1% on the surface of the polymer base membrane treated by the mixed solution, reacting for 15-150 s, removing redundant solvent on the surface, standing for 30-300 s, and drying in an oven for 3-15 min to obtain the hollow nano particle composite nanofiltration membrane; the mass ratio of the hollow nanoparticles to the piperazine is 0.1-20: 1.

2. The hollow nanoparticle composite nanofiltration membrane of claim 1, wherein: the metal organic framework particles are ZIF-8 or MIL-68.

3. The hollow nanoparticle composite nanofiltration membrane of claim 1, wherein: the preparation method of the ZIF-8 comprises the following steps of respectively dissolving zinc nitrate hexahydrate and 2-methylimidazole in absolute methanol to obtain an absolute ethanol solution with the concentration of 0.005-0.06 g/mL of zinc nitrate hexahydrate and an absolute ethanol solution with the concentration of 0.01-0.1 g/mL of 2-methylimidazole, uniformly mixing the absolute ethanol solution of the zinc nitrate hexahydrate and the absolute ethanol solution of the 2-methylimidazole, putting the mixture into a high-pressure reaction kettle, reacting at 150 ℃ for 5 hours, cooling, centrifuging, washing an obtained centrifugal product with methanol for 1-3 times to obtain ZIF-8, and dispersing the ZIF-8 in the methanol solution for later use; the mass ratio of the zinc nitrate hexahydrate to the 2-methylimidazole is 1: 1-5.

4. The hollow nanoparticle composite nanofiltration membrane of claim 1, wherein: the preparation method of the high molecular polymer basement membrane comprises the following steps: dissolving a high molecular material in a polar organic solvent to obtain a high molecular membrane casting solution, stirring, performing ultrasonic treatment, standing, and scraping by a phase inversion method to obtain an ultrafiltration membrane; the mass fraction of the high molecular polymer casting solution is 8-20%.

5. The hollow nanoparticle composite nanofiltration membrane of claim 4, wherein: the high polymer material comprises polyvinylidene fluoride, polypropylene, polyacrylonitrile, polyethylene, polyvinyl chloride, polysulfone, polyether sulfone or polyimide.

6. The hollow nanoparticle composite nanofiltration membrane of claim 4, wherein: the polar organic solvent is N, N-dimethylformamide, N-methylpyrrolidone or dimethylacetamide.

7. The hollow nanoparticle composite nanofiltration membrane of claim 4, wherein: in the step (1), the concentration of the tannic acid aqueous solution is 3-6 mg/mL.

8. The hollow nanoparticle composite nanofiltration membrane of claim 1, wherein: in the step (1), the time for mixing the aqueous solution of tannic acid with the aqueous solution of MOFs is preferably within 30 min.

9. The hollow nanoparticle composite nanofiltration membrane of claim 1, wherein: in the step (2), the drying temperature is 60-90 ℃.

10. The hollow nano-particle composite nanofiltration membrane as claimed in claim 1, applied to salt separation.

Technical Field

The invention relates to a hollow nano-particle composite nanofiltration membrane, a preparation method and application thereof, belonging to the technical field of functional membrane preparation and separation application.

Background

In 1972, Cadotte firstly applies an interfacial polymerization method to prepare a high-performance reverse osmosis composite membrane NS100, the salt rejection rate and the water flux of the membrane are greatly improved compared with those of the membrane prepared by the L-S method, and 90 percent of the current reverse osmosis/nanofiltration membranes worldwide are produced by the interfacial polymerization method.

In recent years, the research heat of interfacial polymerization is still not reduced, the Zhang teacher team of Zhejiang university deeply analyzes the formation process of the interfacial polymerization nanofiltration membrane, and different inhibitors are used for regulating and controlling the membrane surface obtained by interfacial polymerization to construct a Tuling structure. However, in the aspect of practical application, the flux of the reverse osmosis/nanofiltration membrane is very low, the treatment efficiency of the membrane can be greatly improved by using new materials or technical methods, and the method can provide another selectable way for preparing the high-efficiency desalination membrane.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to prepare the hollow nano-particle composite nanofiltration membrane to realize high-efficiency water treatment, and is mainly used for separating salts in the nanofiltration aspect.

The technical scheme adopted by the invention is as follows:

And (2) doping hollow nano particles into a water phase for interfacial polymerization, preparing a polyamide layer on the surface of a self-made ultrafiltration membrane in an interfacial polymerization mode, and immersing the ultrafiltration membrane into water after heat treatment to obtain the modified interfacial polymerization membrane.

the preparation method of the hollow nano-particle composite nanofiltration membrane comprises the following steps:

(1) Mixing 1-10 mg/mL tannic acid aqueous solution with 0.5-20 mg/mL nano-particle aqueous solution, stirring for reaction for 3-120 min, then carrying out centrifugal separation, washing the obtained precipitate with methanol and water to remove impurities, and obtaining etched hollow nano-particles; the volume ratio of the tannic acid aqueous solution to the nano-particle aqueous solution is 0.4-2;

(2) Adding the etched hollow nano particles obtained in the step (1) into a piperazine water solution with the mass fraction of 0.05% -5% to obtain a mixed solution, uniformly coating the mixed solution on the surface of a polymer base membrane, keeping the mixed solution for 30-180 s, then sucking water on the surface of the polymer base membrane, uniformly paving a n-hexane solution of trimesoyl chloride with the mass fraction of 0.01% -1% on the surface of the polymer base membrane treated by the mixed solution, reacting for 15-150 s, removing redundant solvent on the surface, standing for 30-300 s, and drying in an oven for 3-15 min to obtain the hollow nano particle composite nanofiltration membrane; the mass ratio of the hollow nanoparticles to the piperazine is 0.1-20: 1.

further, the metal organic framework particles of the present invention are preferably ZIF-8 or MIL-68.

Further, the preparation method of the ZIF-8 comprises the following steps of respectively dissolving zinc nitrate hexahydrate and 2-methylimidazole in absolute methanol to obtain an absolute ethanol solution of the zinc nitrate hexahydrate with the concentration of 0.005-0.06 g/mL and an absolute ethanol solution of the 2-methylimidazole with the concentration of 0.01-0.1 g/mL, uniformly mixing the absolute ethanol solutions of the zinc nitrate hexahydrate and the 2-methylimidazole, putting the mixture into a high-pressure reaction kettle, reacting for 5 hours at 150 ℃, cooling, centrifuging, washing the obtained centrifugal product with methanol for 1-3 times to obtain the ZIF-8, and dispersing the ZIF-8 in the methanol solution for later use; the mass ratio of the zinc nitrate hexahydrate to the 2-methylimidazole is 1: 1-5.

Further, the preparation method of the high molecular polymer basement membrane comprises the following steps: dissolving a high molecular material in a polar organic solvent to obtain a high molecular membrane casting solution, stirring, performing ultrasonic treatment, standing, and scraping by a phase inversion method to obtain the ultrafiltration membrane.

Still further, the polymer basement membrane made of high molecular materials comprises but is not limited to polyvinylidene fluoride, polypropylene, polyacrylonitrile, polyethylene, polyvinyl chloride, polysulfone, polyethersulfone or polyimide, and the like.

still further, the polar organic solvent may be N, N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, or the like.

Further, the mass fraction of the high molecular polymer casting solution is 8-20%.

Further, in the step (1), the concentration of the aqueous solution of tannic acid is preferably 3-6 mg/mL.

Further, in the step (1), the time for mixing the aqueous solution of tannic acid with the aqueous solution of MOFs is preferably within 30 min.

Further, in the step (1), the cleaning mode is that methanol and water are respectively used for cleaning for 1-3 times.

Further, the hollow nano-particles obtained in the step (1) are not required to be dried, but are stored in an aqueous solution so as to ensure good dispersibility.

Further, in the step (2), the drying temperature is 60-90 ℃.

The hollow nano-particle composite nanofiltration membrane is applied to salt separation.

Compared with the prior art, the invention has the advantages that:

The tannin etched metal organic framework particles are introduced into the interfacial polymerization membrane, hydrophilic groups are introduced on the surfaces of the metal organic framework nano particles, the hydrophilicity of the membrane is improved, the water flux is obviously improved by introducing the hollow nano particles, the membrane preparation process is simple, and the amplification experiment is easy to carry out.

The invention is further illustrated by the following examples.

Drawings

Fig. 1 is an SEM image of a hollow nanoparticle composite membrane.

Detailed Description

The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to the following examples, and various modifications and implementations are included within the technical scope of the present invention without departing from the content and scope of the present invention.

Materials and reagents required in the preparation of the composite membrane:

polysulfone (PSF) Shanghai eosino photochemical plant, polyvinylidene fluoride (PVDF) Shanghai eosino photochemical plant, Polyethersulfone (PES) Shanghai eosino photochemical plant, Polypropylene(PP) Shanghai eosino photochemical factory, Polyacrylonitrile (PAN) Shanghai eosino photochemical factory, polyvinyl chloride (PVC) Shanghai eosino photochemical factory, 2-methylimidazole (MIM) Azadine reagent (Shanghai) Co., Ltd., Zinc nitrate hexahydrate (Zn (NO)₃)₂·6H₂O) Aladdin reagent (Shanghai) Ltd, indium nitrate hydrate (In (NO)₃)₃·xH₂O) Aladdin reagent (Shanghai) Co., Ltd, terephthalic acid (H)₂BDC) alatin reagent (shanghai) ltd, Tannic Acid (TA) alatin reagent (shanghai) ltd, anhydrous methanol alatin reagent (shanghai) ltd, 30% hydrogen peroxide (H)₂O₂) Aladdin reagent (Shanghai) Ltd, sodium sulfate (Na)₂SO₄) Magnesium sulfate (MgSO)₄) Magnesium chloride (MgCl)₂) Sodium nitrate (NaNO)₃) Sodium chloride (NaCl), N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP), Dimethylacetamide (DMAC) by national medicine group chemical reagent Co.

EXAMPLE 1 preparation of hollow ZIF-8 composite nanofiltration Membrane and salt rejection Performance testing

Preparing a polysulfone ultrafiltration membrane: dissolving polysulfone in NMP to prepare a casting solution with the mass fraction of 12%, stirring for 12h, standing for more than 4h, pouring the casting solution on a glass plate, scraping by a scraper with the diameter of 200 mu m, standing for about 15s in the air, then immersing in a water bath to complete phase transformation, immersing in water for more than 12h, and cutting into the required size for later use.

The preparation method of ZIF-8 is as follows, 0.3g zinc nitrate hexahydrate and 0.66g 2-methylimidazole are respectively dissolved in 14mL absolute methanol, are respectively dispersed evenly and then are mixed evenly and put into a high pressure reactor to react for 5h at 150 ℃, then are cooled, centrifuged, washed by methanol for 1 time and dispersed in methanol solution for standby.

Preparing eZIF-8: centrifugally separating the ZIF-8 methanol solution, dissolving the obtained white precipitate in 20mL of water, and taking 10mL of solution A; preparing 6mg/mL tannic acid aqueous solution, and taking 10mL as solution B; and (3) uniformly mixing the A, B two solutions, stirring for 10min, then performing centrifugal separation at 8000r/min, dissolving the obtained precipitate in 20mL of water, and performing ultrasonic dispersion uniformly to obtain the eMOF dispersion liquid.

Preparing a composite nanofiltration membrane: preparing 20mL of piperazine water solution with the mass fraction of 2%, adding 500 mu L of the eMOF dispersion liquid, performing ultrasonic stirring uniformly to obtain C solution, and adding 0.1% of trimesoyl chloride n-hexane solution D; placing a wafer on an ultrafiltration membrane, clamping the wafer by a clamp to form a groove, firstly moving 5mL of the solution C to the surface of the membrane, standing for 2min, absorbing water floating on the surface, after the solution is dried in the air, taking 5mL of the solution D to react on the surface of the membrane for 60s, then pouring off the redundant solution, placing the solution in the air for 2min, keeping the solution in an oven at 80 ℃ for 5min, taking out the solution after the solution is slightly cooled, and then immersing the solution for storage.

And (3) performance testing: the performance of the membrane is tested on a cross flow device, and the water flux of the membrane is 13.2L/(m) under 0.6MPa and 25L/h²H.bar) with a sodium sulfate rejection of 96.3%.

EXAMPLE 2 preparation of hollow ZIF-8 composite nanofiltration Membrane and salt rejection Performance testing

preparing a polysulfone ultrafiltration membrane: preparing 12% by mass of membrane casting solution, wherein the raw material and the polar solvent are respectively polysulfone and NMP, stirring the obtained membrane casting solution for 12h, standing for more than 4h, pouring the membrane casting solution on a glass plate, scraping the membrane casting solution by a scraper with the diameter of 200 mu m, standing in the air for about 15s, then immersing the membrane casting solution in a water bath to complete phase conversion, immersing the membrane casting solution in the water for more than 12h, and cutting the membrane casting solution into required sizes for later use.

the preparation method of ZIF-8 is as follows, 0.3g zinc nitrate hexahydrate and 0.66g 2-methylimidazole are respectively dissolved in 14mL absolute methanol, are respectively dispersed evenly and then are mixed evenly and put into a high pressure reactor to react for 5h at 150 ℃, then are cooled, centrifuged, washed by methanol for 1 time and dispersed in methanol solution for standby.

Preparing eZIF-8: centrifugally separating the ZIF-8 methanol solution, dissolving the obtained white precipitate in 20mL of water, and taking 10mL of solution A; preparing 6mg/mL tannic acid aqueous solution, and taking 10mL as solution B; and (3) uniformly mixing the A, B two solutions, stirring for 10min, then performing centrifugal separation at 8000r/min, dissolving the obtained precipitate in 20mL of water, and performing ultrasonic dispersion uniformly to obtain the eMOF dispersion liquid.

Preparing a composite nanofiltration membrane: preparing 20mL of piperazine water solution with the mass fraction of 2%, adding 1000 muL of the eMOF dispersion liquid, performing ultrasonic stirring uniformly to obtain C solution, and preparing 0.1% of trimesoyl chloride n-hexane solution D; placing a wafer on an ultrafiltration membrane, clamping the wafer by a clamp to form a groove, firstly moving 5mL of the solution C to the surface of the membrane, standing for 2min, absorbing water floating on the surface, after the solution is dried in the air, taking 5mL of the solution D to react on the surface of the membrane for 60s, then pouring off the redundant solution, placing the solution in the air for 2min, keeping the solution in an oven at 80 ℃ for 5min, taking out the solution after the solution is slightly cooled, and then immersing the solution for storage.

And (3) performance testing: the performance of the membrane is tested on a cross flow device, and the water flux of the membrane is 16.8L/(m) under 0.6MPa and 25L/h²h.bar) with a sodium sulfate rejection of 95.8%.

EXAMPLE 3 preparation of hollow MIL-68 composite nanofiltration Membrane and salt rejection Performance testing

Preparing a polysulfone ultrafiltration membrane: preparing 12% by mass of membrane casting solution, wherein the raw material and the polar solvent are respectively polysulfone and NMP, stirring the obtained membrane casting solution for 12h, standing for more than 4h, pouring the membrane casting solution on a glass plate, scraping the membrane casting solution by a scraper with the diameter of 200 mu m, standing in the air for about 15s, then immersing the membrane casting solution in a water bath to complete phase conversion, immersing the membrane casting solution in the water for more than 12h, and cutting the membrane casting solution into required sizes for later use.

The preparation method of MIL-68 comprises the following steps: 78mg of In (NO)₃)₃·xH₂O and 30mg of terephthalic acid (H)₂BDC) was dissolved in 9mL DMF. Stirring at 25 deg.C for 5min, placing the solution in oil bath, heating at 100 deg.C for 1 hr, centrifuging to collect precipitate, washing with a large amount of methanol, and air drying.

TA etch MIL-68: in a typical experiment, 8mg of prepared MIL-68 was placed in a TA solution (50mg/mL) for 3 days, centrifuged, washed with water and methanol, and then dispersed in the aqueous phase for storage.

Preparing a composite nanofiltration membrane: preparing 20mL of piperazine water solution with the mass fraction of 2%, adding 500 mu L of the eMOF dispersion liquid, performing ultrasonic stirring uniformly to obtain C solution, and adding 0.1% of trimesoyl chloride n-hexane solution D; placing a wafer on an ultrafiltration membrane, clamping the wafer by a clamp to form a groove, firstly moving 5mL of the solution C to the surface of the membrane, standing for 2min, absorbing water floating on the surface, after the solution is dried in the air, taking 5mL of the solution D to react on the surface of the membrane for 60s, then pouring off the redundant solution, placing the solution in the air for 2min, keeping the solution in an oven at 80 ℃ for 5min, taking out the solution after the solution is slightly cooled, and then immersing the solution for storage.

And (3) performance testing: in thatThe performance of the membrane is tested on a cross flow device, and the water flux of the membrane is 13.5L/(m) under 0.6MPa and 25L/h²H.bar) with a sodium sulfate rejection of 95.1%.

Comparative example 1 preparation of interfacial polymerization composite nanofiltration membrane and salt rejection performance test

Preparing a polysulfone ultrafiltration membrane: preparing 12% by mass of membrane casting solution, wherein the raw material and the polar solvent are respectively polysulfone and NMP, stirring the obtained membrane casting solution for 12h, standing for more than 4h, pouring the membrane casting solution on a glass plate, scraping the membrane casting solution by a scraper with the diameter of 200 mu m, standing in the air for about 15s, then immersing the membrane casting solution in a water bath to complete phase conversion, immersing the membrane casting solution in the water for more than 12h, and cutting the membrane casting solution into required sizes for later use.

Preparing a composite nanofiltration membrane: preparing 20mL A of piperazine aqueous solution with the mass fraction of 2% and 0.1% of trimesoyl chloride n-hexane solution B; placing a wafer on an ultrafiltration membrane, clamping the wafer by a clamp to form a groove, firstly moving 5mL of the solution C to the surface of the membrane, standing for 2min, absorbing water floating on the surface, after the solution is dried in the air, taking 5mL of the solution D to react on the surface of the membrane for 60s, then pouring off the redundant solution, placing the solution in the air for 2min, keeping the solution in an oven at 80 ℃ for 5min, taking out the solution after the solution is slightly cooled, and then immersing the solution for storage.

And (3) performance testing: the performance of the membrane is tested on a cross flow device, and the water flux of the membrane is 10.5L/(m) under 0.6MPa and 25L/h²H.bar) with a sodium sulfate rejection of 95.5%.