High-strength hollow fiber ultrafiltration membrane and method for preparing the same

Abstract

The application belongs to the field of composite materials, and particularly relates to a high-strength hollow fiber ultrafiltration membrane and a preparation method thereof, which comprises the following steps: slowly adding 24.5 parts of diethylene glycol into 54 parts of dimethylacetamide, adding one of 1,10-phenanthroline modified ZIF-8, 1,10-phenanthroline modified ZIF-8 / Fe composite or 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite at a stirring speed of 500 r / min, adding 18 parts of polyethersulfone after stirring for 1 hour, continuing to stir and heating to 80 DEG C, stirring for 24 h under a nitrogen atmosphere, and stirring at a speed of 500 r / min; then naturally cooling to 30 DEG C, and maintaining vacuum degassing at 30 DEG C for one day. The prepared hollow fiber ultrafiltration membrane solves the problem of low bovine serum protein retention rate of the hollow fiber ultrafiltration membrane caused by the use of 1,10-phenanthroline modified ZIF-8 / Fe composite, improves the tensile strength, and maintains the bovine serum protein retention rate and high pure water flux.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to a high-strength hollow fiber ultrafiltration membrane and its preparation method. Background Technology

[0002] Ultrafiltration technology is a type of membrane filtration. The unique pore size of ultrafiltration membranes (0.01~0.1µm) can effectively trap bacteria, viruses, colloids, etc., to achieve separation, classification, purification, and concentration.

[0003] Ultrafiltration, due to its lack of phase change and simple operation, is widely used in water treatment, food industry, and biochemical engineering. With advancements in ultrafiltration technology, its contribution to human society will only increase.

[0004] Hollow fiber ultrafiltration membranes have the advantages of high packing density, easy production process control, and low production cost, making them the main form of ultrafiltration membranes and the current mainstream in the market.

[0005] Ultrafiltration membranes are mainly made of materials such as PVDF, PES, PS, PVC, PAN, and PP. In existing technologies, adding ZIF-8 to PES ultrafiltration membranes increases the water flux, but the strength of the membrane fibers still needs improvement. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a high-strength hollow fiber ultrafiltration membrane and its preparation method.

[0007] The technical solution of the present invention is as follows: a high-strength hollow fiber ultrafiltration membrane, wherein the preparation method of the high-strength hollow fiber ultrafiltration membrane includes the following steps:

[0008] Step S1: Preparation of casting solution: By weight, 24.5 parts of diethylene glycol were slowly added to 54 parts of dimethylacetamide. One of the following was added under stirring speed of 500 r / min: 1,10-phenanthroline modified ZIF-8, 1,10-phenanthroline modified ZIF-8 / Fe complex, or 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 complex. After stirring for 1 hour, 18 parts of polyethersulfone were added. Stirring was continued and the temperature was raised to 80℃. Stirring was carried out under nitrogen atmosphere for 24 hours at a stirring speed of 500 r / min. Then, the mixture was naturally cooled to 30℃ and vacuum degassed at 30℃ for one day to obtain the casting solution.

[0009] Step S2: The casting solution is passed through the spinning nozzle mold under a pressure of 0.4 MPa, maintained in air for 2-3 seconds, and then directly entered a 30°C coagulation water bath. It is then soaked in 1.0 M sulfuric acid for 2 hours, then washed in pure water, then soaked in methanol and n-hexane respectively, and then dried at 60°C.

[0010] Furthermore, in step S1, 0.5 parts of 1,10-phenanthroline-modified ZIF-8 are added.

[0011] Furthermore, in step S1, 0.5 parts of a 1,10-phenanthroline-modified ZIF-8 / Fe complex are added.

[0012] Furthermore, in step S1, 1,10-phenanthroline-modified ZIF-8 / Fe / CeO2 is added, with a content of 0.5-1 part.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] By adding 1,10-phenanthroline to modify the ZIF-8 / Fe / CeO2 complex, the problem of low bovine serum albumin retention rate of hollow fiber ultrafiltration membranes caused by using 1,10-phenanthroline to modify ZIF-8 / Fe was solved. While improving tensile strength, the retention rate of bovine serum albumin and a high pure water flux were maintained. Detailed Implementation

[0015] The present invention will be further described below with reference to the embodiments. Unless otherwise specified, the contents in the embodiments are all parts by weight.

[0016] The synthesis method of ZIF-8 in this invention is as follows:

[0017] 3.00 g of zinc nitrate hexahydrate was dissolved in 50 mL of methanol, and then added to 100 mL of methanol solution containing 3.34 g of 2-methylimidazole. The mixture was stirred for 12 h, and the suspension was washed three times with methanol by centrifugation. Then it was dried overnight in a vacuum oven at 60 °C to obtain ZIF-8.

[0018] The method for synthesizing 1,10-phenanthroline-modified ZIF-8 in this invention is as follows:

[0019] 0.5 g ZIF-8 and 0.125 g 1,10-phenanthroline were dispersed in 45 ml of ethanol and distilled aqueous solution at a volume ratio of 2:1 and magnetically stirred for 2 hours. The mixture was then vacuum dried overnight at 80 °C. The dried product was ground into a fine powder and carbonized in a tube furnace at a heating rate of 5 °C / min, and kept at 900 °C for 3 hours under continuous argon protection. The sample was then naturally cooled to room temperature to obtain 1,10-phenanthroline modified ZIF-8.

[0020] The method for synthesizing the 1,10-phenanthroline-modified ZIF-8 / Fe complex in this invention is as follows:

[0021] 100 mg of ferrocene and 400 mg of 1,10-phenanthroline-modified ZIF-8 were added to a tube furnace for carbonization. The furnace center temperature was increased to 120 °C at a rate of 2 °C / min and held at this temperature for 3 hours. Subsequently, the temperature was further increased to 900 °C and held at a rate of 5 °C / min for pyrolysis. Then, the mixture was naturally cooled to room temperature to obtain the 1,10-phenanthroline-modified ZIF-8 / Fe complex.

[0022] The method for synthesizing the 1,10-phenanthroline-modified ZIF-8 / Fe / CeO2 complex in this invention is as follows:

[0023] 80 mg of 1,10-phenanthroline-modified ZIF-8 / Fe complex and 30 mg of Ce(acac)3 were dispersed in 10 ml of distilled water and sonicated for 30 min, followed by lyophilization overnight. Then, the powder was annealed at low temperature for 3 h by heating to 120 °C (heating rate of 2 °C / min) in an argon atmosphere. The temperature was then further increased to 900 °C at a heating rate of 5 °C / min. The sample was then allowed to cool naturally to room temperature, finally yielding the 1,10-phenanthroline-modified ZIF-8 / Fe / CeO2 complex.

[0024] The method for determining the pure water flux in this invention is as follows: Using a hollow fiber membrane pure water flux testing device based on existing technology, the membrane is pre-pressed at 0.1 MPa for 30 minutes, and then tested within a time t. The product water volume is V, and the membrane filtration area is S. The purified water flux is then J = V / St, where V is in L, t is in h, and S is in m³. 2 The average flux of 5 different membrane fibers in the same batch is taken as the flux of that batch of membrane fibers.

[0025] The method for determining bovine serum albumin retention rate in this invention is a commonly used method in the prior art, and specifically includes the following steps:

[0026] First, a series of BSA solutions were prepared, and the absorbance of these BSA solutions was measured at a wavelength of 280 nm using a UV-Vis spectrophotometer. Then, a standard curve of BSA concentration versus absorbance was plotted.

[0027] Prepare a 1 g·L⁻¹ BSA solution and pour it into the liquid tank of a self-made testing device (using a testing device with the same pure water flux as hollow fiber membrane fibers). Fix the membrane module to the branch port of the device, and then pre-pressurize it at 0.1 MPa for 15 minutes before collecting the filtrate. Measure 5 samples, each sample 3 times, and take the average value.

[0028] The tensile strength measurement method in this invention is as follows: The tensile strength of the membrane is tested using an electronic single-fiber tensile tester (LLY-06). First, the membrane filament linear density is obtained by weighing with a balance. The clamping distance is 10 mm, the stretching rate is 10 mm / min, and each sample is measured 3 times, and the average value is taken.

[0029] Example 1

[0030] Step S1: Preparation of casting solution: 24.5 parts of diethylene glycol were slowly added to 54 parts of dimethylacetamide. 0.5 parts of ZIF-8 were added while stirring at 500 r / min. After stirring for 1 hour, 18 parts of polyethersulfone were added. Stirring was continued and the temperature was raised to 80℃. Stirring was carried out under a nitrogen atmosphere for 24 hours at a stirring speed of 500 r / min. Then, the mixture was naturally cooled to 30℃ and vacuum degassed at 30℃ for one day to obtain the casting solution.

[0031] Step S2: The casting solution is passed through the spinning nozzle mold under a pressure of 0.4 MPa, maintained in air for 2-3 seconds, and then directly entered a 30°C coagulation water bath. It is then soaked in 1.0 M sulfuric acid for 2 hours, then washed in pure water, then soaked in methanol and n-hexane respectively, and then dried at 60°C.

[0032] The hollow fiber ultrafiltration membrane was subjected to performance testing. The tensile strength of the hollow fiber ultrafiltration membrane at room temperature was 17 MPa, and the pure water flux at 0.1 MPa was 1323 L / m³. 2 h, the retention rate of bovine serum albumin was 92%.

[0033] Example 2

[0034] Step S1: Preparation of casting solution: 24.5 parts of diethylene glycol were slowly added to 54 parts of dimethylacetamide. 0.5 parts of 1,10-phenanthroline-modified ZIF-8 were added while stirring at 500 r / min. After stirring for 1 hour, 18 parts of polyethersulfone were added. Stirring continued and the temperature was raised to 80℃. Stirring was carried out for 24 hours under a nitrogen atmosphere at a stirring speed of 500 r / min. Then, the mixture was naturally cooled to 30℃ and vacuum degassed at 30℃ for one day to obtain the casting solution.

[0035] Step S2: The casting solution is passed through the spinning nozzle mold under a pressure of 0.4 MPa, maintained in air for 2-3 seconds, and then directly entered a 30°C coagulation water bath. It is then soaked in 1.0 M sulfuric acid for 2 hours, then washed in pure water, then soaked in methanol and n-hexane respectively, and then dried at 60°C.

[0036] The hollow fiber ultrafiltration membrane was subjected to performance testing. The tensile strength of the hollow fiber ultrafiltration membrane at room temperature was 23 MPa, and the pure water flux at 0.1 MPa was 1357 L / m³. 2h, the retention rate of bovine serum albumin was 81%.

[0037] Example 3

[0038] Step S1: Preparation of casting solution: 24.5 parts of diethylene glycol were slowly added to 54 parts of dimethylacetamide. 0.5 parts of 1,10-phenanthroline-modified ZIF-8 / Fe composite were added while stirring at 500 r / min. After stirring for 1 hour, 18 parts of polyethersulfone were added. Stirring continued and the temperature was raised to 80℃. Stirring was carried out under a nitrogen atmosphere for 24 hours at a stirring speed of 500 r / min. Then, the mixture was naturally cooled to 30℃ and vacuum degassed at 30℃ for one day to obtain the casting solution.

[0039] Step S2: The casting solution is passed through the spinning nozzle mold under a pressure of 0.4 MPa, maintained in air for 2-3 seconds, and then directly entered a 30°C coagulation water bath. It is then soaked in 1.0 M sulfuric acid for 2 hours, then washed in pure water, then soaked in methanol and n-hexane respectively, and then dried at 60°C.

[0040] The hollow fiber ultrafiltration membrane was subjected to performance testing. The tensile strength of the hollow fiber ultrafiltration membrane at room temperature was 35 MPa, and the pure water flux at 0.1 MPa was 1342 L / m³. 2 h, the retention rate of bovine serum albumin is 60%.

[0041] Example 4

[0042] Step S1: Preparation of casting solution: 24.5 parts of diethylene glycol were slowly added to 54 parts of dimethylacetamide. 0.5 parts of 1,10-phenanthroline-modified ZIF-8 / Fe / CeO2 composite were added while stirring at 500 r / min. After stirring for 1 hour, 18 parts of polyethersulfone were added. Stirring continued and the temperature was raised to 80℃. Stirring was carried out under a nitrogen atmosphere for 24 hours at a stirring speed of 500 r / min. Then, the mixture was naturally cooled to 30℃ and vacuum degassed at 30℃ for one day to obtain the casting solution.

[0043] Step S2: The casting solution is passed through the spinning nozzle mold under a pressure of 0.4 MPa, maintained in air for 2-3 seconds, and then directly entered a 30°C coagulation water bath. It is then soaked in 1.0 M sulfuric acid for 2 hours, then washed in pure water, then soaked in methanol and n-hexane respectively, and then dried at 60°C.

[0044] The hollow fiber ultrafiltration membrane was subjected to performance testing. The tensile strength of the hollow fiber ultrafiltration membrane at room temperature was 32 MPa, and the pure water flux at 0.1 MPa was 1357 L / m³. 2 h, the retention rate of bovine serum albumin was 88%.

[0045] Example 5

[0046] Step S1: Preparation of casting solution: 24.5 parts of diethylene glycol were slowly added to 54 parts of dimethylacetamide. 0.7 parts of 1,10-phenanthroline-modified ZIF-8 / Fe / CeO2 composite were added while stirring at 500 r / min. After stirring for 1 hour, 18 parts of polyethersulfone were added. Stirring continued and the temperature was raised to 80℃. Stirring was carried out under a nitrogen atmosphere for 24 hours at a stirring speed of 500 r / min. Then, the mixture was naturally cooled to 30℃ and vacuum degassed at 30℃ for one day to obtain the casting solution.

[0047] Step S2: The casting solution is passed through the spinning nozzle mold under a pressure of 0.4 MPa, maintained in air for 2-3 seconds, and then directly entered a 30°C coagulation water bath. It is then soaked in 1.0 M sulfuric acid for 2 hours, then washed in pure water, then soaked in methanol and n-hexane respectively, and then dried at 60°C.

[0048] The hollow fiber ultrafiltration membrane was subjected to performance testing. The tensile strength of the hollow fiber ultrafiltration membrane at room temperature was 36 MPa, and the pure water flux at 0.1 MPa was 1270 L / m³. 2 h, the retention rate of bovine serum albumin was 87%.

[0049] Example 6

[0050] Step S1: Preparation of casting solution: 24.5 parts of diethylene glycol were slowly added to 54 parts of dimethylacetamide. 1 part of 1,10-phenanthroline-modified ZIF-8 / Fe / CeO2 composite was added while stirring at 500 r / min. After stirring for 1 hour, 18 parts of polyethersulfone were added. Stirring continued and the temperature was raised to 80℃. Stirring was carried out under a nitrogen atmosphere for 24 hours at a stirring speed of 500 r / min. Then, the mixture was naturally cooled to 30℃ and vacuum degassed at 30℃ for one day to obtain the casting solution.

[0051] Step S2: The casting solution is passed through the spinning nozzle mold under a pressure of 0.4 MPa, maintained in air for 2-3 seconds, and then directly entered a 30°C coagulation water bath. It is then soaked in 1.0 M sulfuric acid for 2 hours, then washed in pure water, then soaked in methanol and n-hexane respectively, and then dried at 60°C.

[0052] The hollow fiber ultrafiltration membrane was subjected to performance testing. The tensile strength of the hollow fiber ultrafiltration membrane at room temperature was 35 MPa, and the pure water flux at 0.1 MPa was 812 L / m³. 2 h, the retention rate of bovine serum albumin was 86%.

[0053] The test data shows that the addition of 1,10-phenanthroline-modified ZIF-8 / Fe / CeO2 improves the tensile strength of hollow fiber membranes, but affects the pure water flux, so its content needs to be strictly controlled.

[0054] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, any equivalent changes or modifications made in accordance with the principles described in the claims of the present invention should be within the scope of the present invention patent application.

Claims

1. A high-strength hollow fiber ultrafiltration membrane, characterized in that, The preparation method of the high-strength hollow fiber ultrafiltration membrane comprises the following steps: Step S1: preparation of casting solution: 24.5 parts of diethylene glycol is slowly added to 54 parts of dimethylacetamide, and one of 1,10-phenanthroline modified ZIF-8, 1,10-phenanthroline modified ZIF-8 / Fe composite or 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite is added under stirring at a speed of 500 r / min, 18 parts of polyether sulfone is added after stirring for 1 hour, continue to stir and heat to 80℃, stir for 24h under nitrogen atmosphere, the stirring speed is 500r / min; then naturally cool to 30℃, maintain 30℃ under vacuum degassing for one day, get the casting solution; Step S2: the casting solution is passed through a spinning nozzle die under a pressure of 0.4Mpa, maintained in air for 2-3s, then directly into a 30℃ coagulation water bath, then soaked in 1.0M sulfuric acid for 2h, then continue to clean in pure water, then soaked in methanol and n-hexane respectively, then dried at 60℃.

2. The high-strength hollow fiber ultrafiltration membrane according to claim 1, characterized in that, The content of 1,10-phenanthroline modified ZIF-8 added in step S1 is 0.5 parts by weight.

3. The high-strength hollow fiber ultrafiltration membrane according to claim 1, characterized in that, The content of 1,10-phenanthroline modified ZIF-8 / Fe composite added in step S1 is 0.5 parts by weight.

4. The high-strength hollow fiber ultrafiltration membrane according to claim 1, characterized in that, The content of 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite added in step S1 is 0.5-1 parts by weight.

5. The high-strength hollow fiber ultrafiltration membrane according to claim 4, characterized in that, The content of 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite added in step S1 is 0.7-1 parts by weight.

6. The high-strength hollow fiber ultrafiltration membrane according to claim 4, characterized in that, The content of 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite added in step S1 is 0.7 parts by weight.

7. A method for producing a high-strength hollow fiber ultrafiltration membrane, characterized by, The preparation method of the high-strength hollow fiber ultrafiltration membrane comprises the following steps: Step S1: preparation of casting solution: 24.5 parts of diethylene glycol is slowly added to 54 parts of dimethylacetamide, and one of 1,10-phenanthroline modified ZIF-8, 1,10-phenanthroline modified ZIF-8 / Fe composite or 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite is added under stirring at a speed of 500 r / min, 18 parts of polyether sulfone is added after stirring for 1 hour, continue to stir and heat to 80℃, stir for 24h under nitrogen atmosphere, the stirring speed is 500r / min; then naturally cool to 30℃, maintain 30℃ under vacuum degassing for one day, get the casting solution; Step S2: the casting solution is passed through a spinning nozzle die under a pressure of 0.4Mpa, maintained in air for 2-3s, then directly into a 30℃ coagulation water bath, then soaked in 1.0M sulfuric acid for 2h, then continue to clean in pure water, then soaked in methanol and n-hexane respectively, then dried at 60℃. The preparation method of the 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite is as follows: 80 mg of 1,10-phenanthroline modified ZIF-8 / Fe composite and 30 mg of Ce(acac)3 are dispersed in 10 ml of distilled water, ultrasonic treatment is carried out for 30 min, and then freeze-drying is carried out overnight; then, low-temperature annealing treatment is carried out by heating the powder to 120 DEG C at an argon gas flow, the temperature rising rate is 2 DEG C / min, and the treatment time is 3 hours; then, the temperature is further increased to 900 DEG C, the temperature rising rate is 5 DEG C / min; then, the sample is naturally cooled to room temperature; and finally, the 1,10-phenanthroline modified ZIF-8 / Fe / CeO2 composite is obtained.