阅读说明：本技术 一种常温原位生长制备uio-66-nh2纳滤膜的方法 (Normal-temperature in-situ growth preparation of UIO-66-NH2Method for preparing nanofiltration membrane ) 是由 徐艳超 林红军 李志文 陶敏 于 2021-09-22 设计创作，主要内容包括：本发明提供一种常温原位生长制备UiO-66-NH-(2)纳滤膜的方法,包括：将聚合物原料和溶剂,配制成17％的混合溶液,在混合溶液中添加1～7％的致孔剂,配置成铸膜液,所用的致孔剂为聚乙烯吡咯烷酮(PVP)；对铸膜液采用浸没式相转化的方法制备基膜；将ZrCl-(4)溶解在甲酸和乙醇的混合溶液中,配制成浓度为2mmol～10mmol/27ml的第一溶液,将氨基对苯二甲酸溶解在甲酸、纯水、乙醇的混合溶液中,配制成2mmol～10mmol/35ml的第二溶液；将基膜浸没在第一溶液中,静置,使基膜表面溶剂挥发得到第一膜；将第一膜浸没在第二溶液中,静置后,浸泡在无水乙醇中30min,用去离子水漂洗5min,得到UiO-66-NH-(2)纳滤膜,该方法操作简单,膜的通量大,截留率高,易于实现工业化生产。(The invention provides a method for preparing UiO-66-NH by normal temperature in-situ growth 2 A method of nanofiltration membrane comprising: preparing a 17% mixed solution from a polymer raw material and a solvent, adding 1-7% of a pore-forming agent into the mixed solution, and preparing a membrane casting solution, wherein the pore-forming agent is polyvinylpyrrolidone (PVP); preparing a base film from the casting solution by adopting an immersion type phase inversion method; reacting ZrCl 4 Dissolving in a mixed solution of formic acid and ethanol to prepare a first solution with the concentration of 2 mmol-10 mmol/27ml, and dissolving amino terephthalic acid in a mixed solution of formic acid, pure water and ethanol to prepare a second solution with the concentration of 2 mmol-10 mmol/35 ml; immersing the base film in the first solution, standing, and volatilizing a solvent on the surface of the base film to obtain a first film; immersing the first membrane in the second solution, standing, soaking in absolute ethanol for 30min, rinsing with deionized water for 5min to obtain UiO-66-NH 2 Nanofiltration membrane, process of operationSimple, large flux of the membrane, high retention rate and easy realization of industrial production.)

1. Preparation of UiO-66-NH by normal temperature in-situ growth₂The nanofiltration membrane method is characterized by comprising the following steps:

providing a base film, a first solution and a second solution; the first solution is ZrCl with the concentration of 2 mmol-10 mmol/27ml₄The second solution is an amino terephthalic acid solution with the concentration of 2 mmol-10 mmol/35 ml; immersing the base film in the first solution, standing at 25 ℃ to volatilize a solvent on the surface of the base film to obtain a first film;

immersing the first membrane in a second solution, standing for 1-24 h, and rinsing with deionized water to obtain UiO-66-NH₂A nanofiltration membrane.

2. The method of claim 1, wherein the step of preparing UiO-66-NH comprises growing in situ at room temperature₂A method of nanofiltration membrane, wherein providing a base membrane comprises:

preparing a 17% mixed solution by taking a proper amount of polymer raw materials and a solvent, wherein the polymer raw materials are one or a combination of Polyacrylonitrile (PAN), polyether sulfone (PES), Polysulfone (PSF) and Polyimide (PI), and the solvent is one or a combination of polyvinylpyrrolidone (PVP), dimethyl sulfoxide (DMSO) and N, N-Dimethylformamide (DMF);

adding 1-7% of pore-forming agent into the mixed solution to prepare a membrane casting solution, and stirring until the membrane casting solution is completely dissolved, wherein the pore-forming agent is polyvinylpyrrolidone (PVP);

preparing a base film by adopting an immersion type phase inversion method for the casting solution, and washing with deionized water to obtain the base film.

3. The method of claim 1, wherein the step of preparing UiO-66-NH comprises growing in situ at room temperature₂A method of nanofiltration membrane, wherein providing a first solution comprises:

reacting ZrCl₄Dissolved in a mixed solution of formic acid and ethanol.

4. The method of claim 1, wherein the step of preparing UiO-66-NH comprises growing in situ at room temperature₂A method of nanofiltration membrane, wherein providing a second solution comprises:

dissolving amino terephthalic acid in a mixed solution of formic acid, pure water and ethanol.

5. The method of claim 1, wherein the step of preparing UiO-66-NH comprises growing in situ at room temperature₂A method for preparing nano-filter membrane is characterized in that,

and immersing the first membrane in the second solution, standing for 1-24 h, and soaking in absolute ethyl alcohol for 30 min.

6. The method of claim 2, wherein the step of preparing UiO-66-NH comprises growing in situ at room temperature₂The nanofiltration membrane method is characterized in that the polymer raw material is polyether sulfone (PES), and the solvent is N, N-Dimethylformamide (DMF).

7. The method of claim 6, wherein the step of preparing UiO-66-NH comprises growing the precursor solution at room temperature in situ₂The nanofiltration membrane method is characterized in that 7% of pore-forming agent is added into the mixed solution.

8. The method of claim 7, wherein the step of preparing UiO-66-NH comprises growing in situ at room temperature₂The method of nanofiltration membrane is characterized in that ZrCl is contained in the first solution₄The concentration was 5mmol/27ml and the concentration of the amino terephthalic acid in the second solution was 2mmol/35 ml.

Technical Field

The invention relates to a preparation method of a film, in particular to normal-temperature in-situ growth UiO-66-NH₂And (4) preparing the nanofiltration membrane.

Background

Nanofiltration membrane separation is an advanced substance separation and purification technology, and is widely applied to the fields of chemical industry, medicine, printing and dyeing, seawater desalination and the like due to the characteristics of high efficiency, low energy consumption, high single-pass separation degree and the like, and particularly widely applied to water treatment processes in the fields of industrial wastewater, medical wastewater, printing and dyeing wastewater and the like by virtue of the advantages of environmental friendliness, no physical and chemical change in the separation process and the like.

The in-situ growth method is one of hot spot techniques for preparing nanofiltration separation membranes, and the method is a process of directly immersing a carrier in a growth stock solution to obtain a membrane material on the premise that no crystal is attached to the surface of the carrier in advance, wherein nucleation, growth and crosslinking symbiosis on the carrier are all completed in one synthesis step, ideally, continuous MOFs crystals grow in the carrier or on the surface of the carrier, and the continuous crystal membranes play a decisive role in the process of separating pollutants.

The metal organic framework Materials (MOFs) are porous materials formed by coordination and connection of metal ions or ion clusters and organic ligands, according to the composition, the pores of the MOFs are different from 0.3nm to 10nm, which is undoubtedly a good molecular sieve tool, so that the MOFs have high selectivity when separating pollutant molecules in water, and characteristics such as rich and various pore channel structures, extremely high porosity, excellent post-synthesis modification and the like provide wide application space for the MOFs in the field of membrane separation, and the UO series MOFs are formed by a regular octahedral secondary structural unit [ Zr ] of the Zr₆O₄(OH)₄]Is formed by coordination and connection with 12 organic ligands terephthalic acid, and Zr is known from soft and hard acid-base theory⁴⁺The coordination with the carboxylic acid ligand is combined in a manner of hard acid-hard base, and the coordination bond has strong strength, so that the UiO series MOFs material has excellent water stability and thermal stability.

However, the existing preparation process or method of the MOFs nanofiltration membrane has the problems of high operation difficulty, low membrane flux, low rejection rate, difficulty in industrial production and the like.

Disclosure of Invention

The invention provides a method for preparing UiO-66-NH by normal temperature and pressure in-situ growth₂The method of the nanofiltration membrane has the advantages of simple operation, large membrane flux, high rejection rate and easy realization of industrial production.

The invention provides a method for preparing UiO-66-NH by normal temperature in-situ growth₂A method of nanofiltration membrane comprising the steps of:

providing a base film, a first solution and a second solution; the first solution is ZrCl with the concentration of 2 mmol-10 mmol/27ml₄The second solution is an amino terephthalic acid solution with the concentration of 2 mmol-10 mmol/35 ml; immersing the base film in the first solution, standing at 25 ℃ to volatilize a solvent on the surface of the base film to obtain a first film;

immersing the first membrane in a second solution, standing for 1-24 h, and rinsing with deionized water to obtain UiO-66-NH₂A nanofiltration membrane.

Further, providing a base film comprises:

preparing a 17% mixed solution by taking a proper amount of polymer raw materials and a solvent, wherein the polymer raw materials are one or a combination of Polyacrylonitrile (PAN), polyether sulfone (PES), Polysulfone (PSF) and Polyimide (PI), and the solvent is one or a combination of polyvinylpyrrolidone (PVP), dimethyl sulfoxide (DMSO) and N, N-Dimethylformamide (DMF);

adding 1-7% of pore-forming agent into the mixed solution to prepare a membrane casting solution, and stirring until the membrane casting solution is completely dissolved, wherein the pore-forming agent is pyrrolidone (PVP);

preparing a base film by adopting an immersion type phase inversion method for the casting solution, and washing with deionized water to obtain the base film.

Further, providing the first solution comprises:

reacting ZrCl₄Dissolved in a mixed solution of formic acid and ethanol.

Further, providing the second solution comprises:

dissolving amino terephthalic acid in a mixed solution of formic acid, pure water and ethanol.

Further, in the above-mentioned case,

and immersing the first membrane in the second solution, standing for 1-24 h, and soaking in absolute ethyl alcohol for 30 min.

Further, the polymer raw material is polyether sulfone (PES), and the solvent is N, N-Dimethylformamide (DMF).

Further, a porogen was added to the mixed solution in an amount of 7%.

Further, ZrCl is contained in the first solution₄The concentration was 5mmol/27ml and the concentration of the amino terephthalic acid in the second solution was 2mmol/35 ml.

Has the advantages that: the embodiment of the invention provides a method for preparing UiO-66-NH by normal-temperature in-situ growth₂A method of nanofiltration membrane comprising the steps of: preparing a 17% mixed solution by taking a proper amount of polymer raw materials and a solvent, wherein the polymer raw materials are one or a combination of Polyacrylonitrile (PAN), polyether sulfone (PES), Polysulfone (PSF) and Polyimide (PI), and the solvent is one or a combination of polyvinylpyrrolidone (PVP), dimethyl sulfoxide (DMSO) and N, N-Dimethylformamide (DMF); adding 1-7% of pore-forming agent into the mixed solution to prepare a membrane casting solution, and stirring until the membrane casting solution is completely dissolved, wherein the pore-forming agent is polyvinylpyrrolidone (PVP); preparing a base film by adopting an immersion type phase inversion method for the casting solution, and cleaning the base film by using deionized water; reacting ZrCl₄Dissolving in a mixed solution of formic acid and ethanol to prepare a first solution with the concentration of 2 mmol-10 mmol/27ml, and dissolving amino terephthalic acid in a mixed solution of formic acid, pure water and ethanol to prepare a second solution with the concentration of 2 mmol-10 mmol/35 ml; immersing the base film in the first solution, and standing for about 1h at 25 ℃ to volatilize the solvent on the surface of the base film to obtain a first film; immersing the first membrane in the second solution, standing for 1-24 h, soaking in absolute ethyl alcohol for 30min, rinsing with deionized water for 5min to obtain UiO-66-NH₂The method has the advantages of simple operation, large membrane flux, high rejection rate and easy realization of industrial production.

Drawings

FIG. 1 shows a polyethersulfone raw film produced in example 1Prepared UiO-66-NH₂Infrared spectroscopy of the nanofiltration membrane;

FIG. 2 is a polyethersulfone protomembrane and UiO-66-NH prepared in example 1₂X-ray diffraction pattern of nanofiltration membrane;

FIG. 3 is a polyethersulfone protomembrane and UiO-66-NH prepared in example 1₂Scanning electron microscopy of the nanofiltration membrane;

figure 4 is a graph of the performance of the UiO-66-NH2 nanofiltration membranes prepared in example 1 over time, metal ion concentration, and deionized water content of the growth solution.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1:

a method for preparing a nanofiltration membrane by normal-temperature in-situ growth specifically comprises the following steps.

S1: preparing a mixed solution from a proper amount of 17g of polyether sulfone and 76g N, N-dimethylacetamide;

it is understood that in other embodiments, the Polyethersulfone (PES) used may also be one of Polyacrylonitrile (PAN), Polysulfone (PSF), and Polyimide (PI), or may also be a combination of at least one of Polyacrylonitrile (PAN), Polyethersulfone (PES), Polysulfone (PSF), and Polyimide (PI).

And, N, N-dimethylacetamide can also be selected, polyvinylpyrrolidone (PVP), Dimethylsulfoxide (DMSO) or at least one combination of PVP), Dimethylsulfoxide (DMSO) and N, N-dimethylacetamide;

s2: adding 7g of polyvinylpyrrolidone into the mixed solution to prepare a membrane casting solution, and stirring until the membrane casting solution is completely dissolved;

s3: preparing a base film from the casting solution by adopting an immersion type phase inversion method, and repeatedly cleaning the prepared base film by using deionized water for later use;

s4: adding 5mmol of ZrCl₄Dissolving in a mixed solution of 7ml formic acid and 20ml ethanol to prepare a first solution with the concentration of 5mmol/27 ml; dissolving 2mmol of amino terephthalic acid in a mixed solution of 7ml of formic acid, 8ml of pure water and 20ml of ethanol to prepare a second solution with the concentration of 2mmol/35 ml;

s5: immersing the base film in the first solution, standing for 1h at 25 ℃, and volatilizing the solvent on the surface of the base film at room temperature to obtain a first film;

s6: immersing the first membrane in the second solution, standing for 4h, soaking in absolute ethanol for 30min, rinsing with deionized water for 5min to obtain UiO-66-NH₂A nanofiltration membrane.

Referring to FIG. 1, FIG. 1 shows a polyethersulfone raw membrane and UiO-66-NH obtained in this example₂The infrared spectrum of the nanofiltration membrane shows that the UiO-66-NH obtained by the embodiment is compared with the original polyethersulfone original membrane₂The nanofiltration membrane vibrates at 768cm due to the stretching of Zr-O^-1The peak width is formed at the left and right parts, and the polyvinylpyrrolidone is dissolved at 1666cm^-1The intensity of the C ═ O bond peak decreases on the left and right.

Referring to fig. 2 together, fig. 2 shows the X-ray diffraction patterns of the polyethersulfone raw membrane and the UIO-66-NH2 nanofiltration membrane obtained in this example, and it can be seen that the diffraction peaks are evident at 7.5 ° and 8.5 ° 2 θ, which proves that UIO-66-NH is grown on the surface of the polyethersulfone membrane₂And (4) crystals.

Referring to FIG. 3, FIG. 2 shows a scanning electron microscope image of a polyethersulfone raw membrane and the UIO-66-NH2 nanofiltration membrane obtained in this example, which shows that the polyethersulfone raw membrane has smooth and no obvious protrusions on the surface, while the UIO-66-NH2 nanofiltration membrane obtained in this example has smooth and no obvious protrusions on the surface₂The surface of the nanofiltration membrane shows obvious bulges, namely uniform UiO-66-NH grows on the surface of the membrane₂And (4) crystals.

Further, for UiO-66-NH obtained in this example₂The nanofiltration membrane was subjected to performance testing, please refer to FIG. 4, where FIG. 4 shows UiO-66-NH₂The performance graphs of the nanofiltration membrane along with time, the concentration of metal ions and the content of deionized water in the growth solution show that UiO-66-NH is increased along with the increase of the concentration of the metal ions₂The flux of the nanofiltration membrane gradually decreases and the rejection rate gradually increases because of the high concentration of Zr⁴⁺Not only can generate more UIO-66-NH₂The unit cell also allows for faster reaction times, also UiO-66-NH₂The longer the time is, the important factor for crystal formation, UiO-66-NH₂The better the quality of the crystal, the shapeResultant UIO-66-NH₂And the flux of the membrane is gradually reduced along with the time, the retention rate is gradually increased, and the deionized water plays a role in reducing the reaction rate and improving the crystal quality in the reaction process. Thus, the more deionized water in a ligand solution in a certain range, the slower the reaction rate, the better the quality of the crystals formed, but the excess deionized water will cause the reaction to stop.

Wherein, in the performance test, the pure water flux is measured by the following method:

the filtration of this experiment all adopted the dead-end filtration device, and the effective area of the membrane was 12.56X 10^-4m^-2Filtration was carried out at room temperature at 2bar (N)₂) Then, prepressing the membrane for 30min by using pure water to achieve stable flux, and then calculating the permeation flux P of the nanofiltration membrane by penetrating through the pure water, wherein the calculation formula is as follows:

wherein V is the permeation volume; a is the effective area of the membrane; t is the filtration time; Δ p is the osmotic pressure.

The pure water flux was measured in the following manner:

the retention rate of a nanofiltration membrane on Methyl Orange (MO) and sodium salt of tiger Red (RB) is used for representing the retention effect of the membrane, 35 mu M of dye solution is filtered at room temperature and 2bar of pressure, and the retention rate R (%) of the membrane is calculated according to the following formula:

in the formula C_pAnd C_fThe concentrations of the dyes in the permeate and the stock solutions are indicated, respectively.

Example 2:

in step S2, 1g of polyvinylpyrrolidone is added to the mixed solution, and in step S4 ZrCl is added₄Preparing a first solution with a concentration of 2mmol/27ml, preparing a second solution with 10mmol/35ml of aminoterephthalic acid, and immersing the first membrane in the second membrane in step S6Standing the two solutions for 24 hours, and obtaining UiO-66-NH by the same steps as the example 1₂A nanofiltration membrane.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.