CN111013410A - Polyamide hollow fiber nanofiltration composite membrane and preparation method thereof - Google Patents
Polyamide hollow fiber nanofiltration composite membrane and preparation method thereof Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/56—Polyamides, e.g. polyester-amides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/027—Nanofiltration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/10—Testing of membranes or membrane apparatus; Detecting or repairing leaks
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/08—Hollow fibre membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
- B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction
Abstract
The invention provides a polyamide hollow fiber nanofiltration composite membrane and a preparation method thereof, wherein the polyamide hollow fiber nanofiltration composite membrane comprises the following steps: step 1: activating the polyamide hollow fiber ultrafiltration membrane to form carboxylic acid groups and amino groups on the surface of the polyamide hollow fiber ultrafiltration membrane; step 2: putting the polyamide hollow fiber ultrafiltration membrane subjected to activation treatment into polyamine aqueous solution; and step 3: taking the polyamide hollow fiber ultrafiltration membrane out of the polyamine aqueous solution and putting the polyamide hollow fiber ultrafiltration membrane into a polybasic acyl chloride organic solution, wherein an interfacial polymerization reaction is generated on the surface of the polyamide hollow fiber ultrafiltration membrane to form a separation layer; and 4, step 4: and taking out the polyamide hollow fiber ultrafiltration membrane with the separation layer from the polybasic acyl chloride organic solution and carrying out heat treatment on the polyamide hollow fiber ultrafiltration membrane to obtain the polyamide hollow fiber nanofiltration composite membrane. The invention can effectively reduce the structural defects of the membrane separation layer, strengthen the connection tightness between the base membrane and the separation layer and improve the service performance of the membrane.
Description
Technical Field
The invention relates to the technical field of preparation of separation membranes, in particular to a polyamide hollow fiber nanofiltration composite membrane and a preparation method thereof.
Background
The nano filter membrane is a membrane material with special separation function, the size of the membrane aperture is between 1 and 10 nanometers, the aperture range allows monovalent salt ions such as sodium, potassium and the like to penetrate (the retention rate is less than or equal to 50 percent), and the nano filter membrane has better removal rate on divalent or polyvalent ions and organic matters with the molecular weight between 200 and 1000. In view of the special separation scale of the nanofiltration membrane, the nanofiltration membrane can be used in the fields of water softening (calcium and magnesium ion interception), detoxification (microorganism and heavy metal interception), purification and concentration of special chemical raw materials (such as dye, medicine and biomass) and oil-water separation. Meanwhile, the nanofiltration membrane still has higher flux under lower pressure (0.2-1 MPa), so the operation and maintenance cost is effectively saved. The nanofiltration membrane is suitable for large-scale city tap water treatment and has important significance for drinking water safety guarantee.
The current mainstream nanofiltration membrane is formed by compounding a selective separation layer (mostly made of polyamide material) on the surface of a flat ultrafiltration membrane by an interfacial polymerization method and then rolling a membrane sheet into a membrane element. However, such composite rolled elements have structural limitations: 1) modules such as a water collecting pipe, a separation net, an inter-membrane supporting net and the like are also arranged in the roll-type element besides the membrane, so that the membrane space is greatly occupied, the filling density of the membrane is limited, and the water production efficiency is restricted; 2) pollutants in the narrow flow channel are not easy to wash out, and are easy to cause pollution blockage after long-time operation, so that the requirement on the quality of inlet water is high, an ultramicro filter membrane is often required to be introduced as a pretreatment process, and the operation cost of the nanofiltration membrane process is increased.
Compared with the roll type membrane, the hollow fiber membrane belongs to a self-supporting structure, a supporting device is not needed when the membrane element is assembled, and the unit fiber occupies a small space, so that the area of the filling membrane in the element is larger, and the water production efficiency is obviously improved compared with the roll type membrane. In addition, the hollow fiber structure has good pressure tolerance, can be washed by strong impact, and has better pollution resistance. In view of the advantages, the hollow fiber has great application potential in the manufacture of nanofiltration membranes.
The prior hollow fiber composite nanofiltration membrane has two main technical difficulties: 1) reaction monomers are unevenly distributed on the curved surface base film, and a separation layer formed by polymerization is easy to generate defects, so that the separation performance of the film is influenced; 2) the compatibility of the materials of the base film and the separation layer is poor, the base film and the separation layer lack effective physical or chemical interaction at an interface, so that the separation layer is easy to separate from the base film under long-term operation or extreme water quality conditions, the phenomenon is more obvious on a hollow fiber membrane with a higher specific surface area, and when the separation layer is actually operated (particularly in a high-speed cleaning process), membrane filaments are easy to shake, so that surface friction is generated, the possibility that the separation layer falls off is increased, and the practicability of the membrane is seriously affected by double images.
In summary, there is an urgent need to develop a high-performance hollow fiber nanofiltration membrane that can effectively overcome the above technical problems.
Disclosure of Invention
The invention provides a polyamide hollow fiber nanofiltration composite membrane and a preparation method thereof, which can reduce the structural defects of a membrane separation layer, effectively enhance the connection tightness between a base membrane and the separation layer and improve the service performance of the membrane.
In order to achieve the purpose, the technical scheme of the invention is as follows: a preparation method of a polyamide hollow fiber nanofiltration composite membrane comprises the following steps:
step 1: activating the polyamide hollow fiber ultrafiltration membrane to form carboxylic acid groups and amino groups on the surface of the polyamide hollow fiber ultrafiltration membrane; the polyamide hollow fiber ultrafiltration membrane is used as a base membrane, and the carboxylic acid group and the amino group can effectively improve the hydrophilicity of the surface of the base membrane, so that the adsorption of the surface of the base membrane on subsequent reaction monomers is more uniform, and the defects of a membrane separation layer are reduced;
step 2: putting the polyamide hollow fiber ultrafiltration membrane subjected to activation treatment into polyamine aqueous solution, and performing strong electrostatic interaction with a polyamine monomer charged with positive electricity by utilizing the negative electricity charging characteristic of carboxylic acid groups to generate amidation reaction;
and step 3: taking the polyamide hollow fiber ultrafiltration membrane out of the polyamine aqueous solution and putting the polyamide hollow fiber ultrafiltration membrane into a polybasic acyl chloride organic solution to enable the surface of the polyamide hollow fiber ultrafiltration membrane to generate interfacial polymerization reaction to form a separation layer;
and 5: and taking the polyamide hollow fiber ultrafiltration membrane with the separation layer out of the polybasic acyl chloride organic solution and carrying out heat treatment on the polyamide hollow fiber ultrafiltration membrane to obtain the polyamide hollow fiber nanofiltration composite membrane. And carrying out amidation reaction on the amino group and residual polyacyl chloride on the polyamide hollow fiber ultrafiltration membrane under the action of heat treatment. Under the action of the double amide reaction, stable amido bond acting force is formed between the base membrane and the separation layer, and the problem that the membrane separation layer is easy to fall off is obviously solved.
Optionally, the activation treatment in step 1 specifically includes: putting the polyamide hollow fiber ultrafiltration membrane into an activation reagent for hydrolysis activation; washing is then carried out until the pH is neutral.
Optionally, the hydrolysis activation process specifically includes: the polyamide hollow fiber ultrafiltration membrane is kept in an activating reagent at the temperature of 30-80 ℃ for 30-90 minutes.
Optionally, the activating reagent is an alkaline activating reagent or an oxidative activating reagent with a mass concentration of 0.5% -5%.
Optionally, the activating agent comprises KOH, NaOH, Na2CO3And NaClO.
Optionally, the polyamine aqueous solution comprises a polyethyleneimine aqueous solution with a mass concentration of 0.1% -1%.
Optionally, the mass concentration of the polyethyleneimine aqueous solution is 0.6% to 0.8%.
Alternatively, the weight average molecular weight of the polyethyleneimine is 8000-50000.
Optionally, the poly-acid chloride organic solution comprises a trimesoyl chloride organic solution with a mass concentration of 0.1% -0.5%.
Optionally, the organic solvent in the organic solution of a polybasic acid chloride comprises at least one of pentane, hexane, cyclohexane and heptane.
Optionally, the polyamide hollow fiber ultrafiltration membrane in the step 2 is placed in the polyamine aqueous solution for a holding time of 1-10 minutes.
Optionally, step 3 specifically includes: taking the polyamide hollow fiber ultrafiltration membrane out of the polyamine aqueous solution, vertically suspending for 1-10 minutes, and wiping off the residual polyamine aqueous solution on the surface of the polyamide hollow fiber ultrafiltration membrane; placing the mixture into a polybasic acyl chloride organic solution for keeping for 1-5 minutes.
Optionally, the heat treatment in step 5 includes: and (3) putting the polyamide hollow fiber ultrafiltration membrane into a drying oven at the temperature of 60-80 ℃ for 15-25 minutes.
In order to solve the problems, the invention also provides a polyamide hollow fiber nanofiltration composite membrane prepared by the preparation method of the polyamide hollow fiber nanofiltration composite membrane.
The invention provides a polyamide hollow fiber nanofiltration composite membrane and a preparation method thereof. Compared with the prior art, the polyamide hollow fiber ultrafiltration membrane is used as the base membrane, after activation treatment, the base membrane can simultaneously generate carboxylic acid groups and amino groups, and the carboxylic acid groups and the amino groups can effectively improve the hydrophilicity of the surface of the base membrane, so that the adsorption of the surface of the base membrane on subsequent reaction monomers is more uniform, and the defects of a membrane separation layer are reduced; by utilizing the characteristic of negative charge of carboxylic acid groups, the carboxylic acid groups and the polyamine monomers with positive charge are subjected to amidation reaction, and amino groups and the polyacyl chloride are subjected to amidation reaction, so that stable amido bond acting force is formed between the base membrane and the separation layer under the action of double amide reaction, and the problem that the membrane separation layer is easy to fall off is obviously solved.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments thereof will be described in detail below.
Example 1
The embodiment provides a preparation method of a polyamide hollow fiber nanofiltration composite membrane, which comprises the following steps:
step 1: using a polyamide hollow fiber ultrafiltration membrane as a base membrane, putting the base membrane into a KOH (potassium hydroxide) solution with the temperature of 40 ℃ and the mass concentration of 2 percent for hydrolysis activation treatment for 1 hour, and cleaning the base membrane by using pure water until the pH (hydrogen ion concentration index) is neutral after the activation treatment is finished;
step 2: placing the base film into a 0.6 mass percent polyethyleneimine water solution for 3 minutes, wherein the weight average molecular weight of polyethyleneimine in the embodiment is 8000;
and step 3: taking out the base film from the polyethyleneimine aqueous solution, vertically hanging for 8 minutes, wiping off the redundant polyethyleneimine aqueous solution on the base film by using a paper towel, and immersing the base film into a 0.3% by mass concentration trimesoyl chloride organic solution for 2 minutes to form a separation layer on the surface of the base film, wherein the organic solvent is pentane.
And 4, step 4: and taking the base membrane with the separation layer out of the trimesoyl chloride organic solution, putting the base membrane into a 60-DEG C forced air drying oven to keep the base membrane for 20 minutes, and finally washing the base membrane with water to obtain the polyamide hollow fiber nanofiltration composite membrane.
In this example, the bonding strength between the base membrane and the separation layer of the polyamide hollow fiber nanofiltration composite membrane is measured as follows:
the prepared polyamide hollow fiber nanofiltration composite membrane is placed in an environment with the temperature of 25 ℃ and the pressure of 0.3MPa for separation performance test, and MgSO with the concentration of 2000mg/L is used4The water solution is a test water sample, and a test result is obtained: the desalting rate is 93.6 percent, and the water flux is 21.3L/m2h。
Due to different swelling coefficients, the base membrane and the separation layer can swell to different degrees after being treated by the alcohol solvent, so that the interface bonding force of the base membrane and the separation layer is influenced, and the interface bonding force can be effectively tested by utilizing the principle. In this embodiment, the polyamide hollow fiber nanofiltration composite membrane after the test is soaked in an ethanol solution for 1 hour, and after being washed with water, the separation performance of the polyamide hollow fiber nanofiltration composite membrane is tested by the same method as that described above, so as to obtain the test result: the salt rejection rate is 92.4 percent, and the water flux is 25.3L/m2h。
In this example, a group of polyamide hollow fiber nanofiltration composite membranes prepared without activation treatment was used as a control group, and the bonding strength between the base membrane and the separation layer was measured in the same manner as described above, and it was found that the salt rejection rate of the control group was changed from 92.8% to 70.2%.
In contrast, the separation layer and the base membrane of the polyamide hollow fiber nanofiltration composite membrane obtained by the preparation method provided by the embodiment have more excellent bonding strength.
Example 2
The embodiment provides a preparation method of a polyamide hollow fiber nanofiltration composite membrane, which comprises the following steps:
step 1: using a polyamide hollow fiber ultrafiltration membrane as a base membrane, putting the base membrane into a KOH solution with the temperature of 50 ℃ and the mass concentration of 2 percent for activation treatment for 1 hour, and cleaning the base membrane by using pure water until the pH value is neutral after the activation treatment is finished;
step 2: placing the base film into a 0.7 mass percent polyethyleneimine water solution for keeping for 4 minutes, wherein the weight average molecular weight of polyethyleneimine in the embodiment is 10000;
and step 3: taking out the base film from the polyethyleneimine aqueous solution, vertically hanging for 8 minutes, wiping off the redundant polyethyleneimine aqueous solution on the base film by using a paper towel, and immersing the base film into a 0.4 mass percent trimesoyl chloride organic solution for 2 minutes to form a separation layer on the surface of the base film. In this example, the organic solvent is hexane.
And 4, step 4: and taking the base membrane with the separation layer out of the trimesoyl chloride organic solution, putting the base membrane into a 70 ℃ forced air drying oven for keeping for 20 minutes, and finally washing the base membrane with water to obtain the polyamide hollow fiber nanofiltration composite membrane.
In this example, the bonding strength between the base film and the separation layer of the polyamide hollow fiber nanofiltration composite membrane obtained in the same manner as in example 1 was measured, and the test results were obtained: the membrane desalination rate is changed from 95.7 percent to 94.1 percent, and the water flux is changed from 18L/m2h is changed to 20.8L/m2h。
Example 3
The embodiment provides a preparation method of a polyamide hollow fiber nanofiltration composite membrane, which comprises the following steps:
step 1: using a polyamide hollow fiber ultrafiltration membrane as a base membrane, putting the base membrane into a KOH solution with the temperature of 60 ℃ and the mass concentration of 2 percent for hydrolysis activation treatment for 1 hour, and cleaning the base membrane by using pure water until the pH value is neutral after the activation treatment is finished;
step 2: placing the base film into a polyethyleneimine water solution with the mass concentration of 0.7% for 5 minutes, wherein the weight average molecular weight of the polyethyleneimine in the embodiment is 30000;
and step 3: taking out the base film from the polyethyleneimine aqueous solution, vertically hanging for 8 minutes, wiping off the redundant polyethyleneimine aqueous solution on the base film by using a paper towel, and immersing the base film into a 0.4 mass percent trimesoyl chloride organic solution for 2 minutes to form a separation layer on the surface of the base film. In this example, the organic solvent is hexane.
And 4, step 4: and taking the base membrane with the separation layer out of the trimesoyl chloride organic solution, putting the base membrane into an air-blast drying oven at the temperature of 80 ℃ for keeping for 20 minutes, and finally washing with water to obtain the polyamide hollow fiber nanofiltration composite membrane.
In this example, the bonding strength between the base film and the separation layer of the polyamide hollow fiber nanofiltration composite membrane obtained in the same manner as in example 1 was measured, and the test results were obtained: the salt rejection rate is changed from 96.1 percent to 93.2 percent, and the water flux is changed from 23.8L/m2h is changed to 28.4L/m2h。
Example 4
The embodiment provides a preparation method of a polyamide hollow fiber nanofiltration composite membrane, which comprises the following steps:
step 1: using a polyamide hollow fiber ultrafiltration membrane as a base membrane, putting the base membrane into NaClO (sodium hypochlorite) solution with the temperature of 30 ℃ and the mass concentration of 0.5% for hydrolysis activation treatment for 1 hour, and cleaning the base membrane by using pure water until the pH value is neutral after the activation treatment is finished;
step 2: placing the base film into a polyethyleneimine water solution with the mass concentration of 0.8% for 5 minutes, wherein the weight-average molecular weight of the polyethyleneimine in the embodiment is 50000;
and step 3: taking out the base film from the polyethyleneimine aqueous solution, vertically hanging for 8 minutes, wiping off the redundant polyethyleneimine aqueous solution on the base film by using a paper towel, immersing the base film into a 0.5 mass percent trimesoyl chloride organic solution, and maintaining for 3 minutes to form a separation layer on the surface of the base film. The organic solvent in this example was heptane.
And 4, step 4: and taking the base membrane with the separation layer out of the trimesoyl chloride organic solution, putting the base membrane into a 70 ℃ forced air drying oven for keeping for 20 minutes, and finally washing the base membrane with water to obtain the polyamide hollow fiber nanofiltration composite membrane.
In this example, the bonding strength between the base film and the separation layer of the polyamide hollow fiber nanofiltration composite membrane obtained in the same manner as in example 1 was measured, and the test results were obtained: the desalination rate is changed from 90.2 percent to 89.8 percent, and the water flux is changed from 25.4L/m2h is changed to 29.5L/m2h。
Example 5
The embodiment provides a preparation method of a polyamide hollow fiber nanofiltration composite membrane, which comprises the following steps:
step 1: using a polyamide hollow fiber ultrafiltration membrane as a base membrane, putting the base membrane into NaClO solution with the temperature of 50 ℃ and the mass concentration of 1% for hydrolysis activation treatment for 1 hour, and cleaning the base membrane by using pure water until the pH value is neutral after the activation treatment is finished;
step 2: placing the base film into a polyethyleneimine water solution with the mass concentration of 0.4% for 5 minutes, wherein the weight average molecular weight of the polyethyleneimine in the embodiment is 30000;
and step 3: taking out the base film from the polyethyleneimine aqueous solution, vertically hanging for 8 minutes, wiping off the redundant polyethyleneimine aqueous solution on the base film by using a paper towel, immersing the base film into a 0.3 mass percent trimesoyl chloride organic solution, and maintaining for 3 minutes to form a separation layer on the surface of the base film. The organic solvent in this example was heptane.
And 4, step 4: and taking the base membrane with the separation layer out of the trimesoyl chloride organic solution, putting the base membrane into a 70 ℃ forced air drying oven for keeping for 20 minutes, and finally washing the base membrane with water to obtain the polyamide hollow fiber nanofiltration composite membrane.
In this example, the bonding strength between the base film and the separation layer of the polyamide hollow fiber nanofiltration composite membrane obtained in the same manner as in example 1 was measured, and the test results were obtained: the salt rejection rate is changed from 91.3 percent to 90.5 percent, and the water flux is changed from 22.4L/m2h becomes 25.5L/m2h。
Example 6
The embodiment provides a preparation method of a polyamide hollow fiber nanofiltration composite membrane, which comprises the following steps:
step 1: using a polyamide hollow fiber ultrafiltration membrane as a base membrane, putting the base membrane into NaOH (sodium hydroxide) solution with the temperature of 60 ℃ and the mass concentration of 1% for activation treatment for 1 hour, and cleaning the base membrane by using pure water until the pH value is neutral after the activation treatment is finished;
step 2: placing the base film into a polyethyleneimine water solution with the mass concentration of 0.5% for 5 minutes, wherein the weight average molecular weight of the polyethyleneimine in the embodiment is 10000;
and step 3: taking out the base film from the polyethyleneimine aqueous solution, vertically hanging for 8 minutes, wiping off the redundant polyethyleneimine aqueous solution on the base film by using a paper towel, immersing the base film into a 0.2 mass percent trimesoyl chloride organic solution, and maintaining for 3 minutes to form a separation layer on the surface of the base film. The organic solvent in this example was heptane.
And 4, step 4: and taking the base membrane with the separation layer out of the trimesoyl chloride organic solution, putting the base membrane into a 70 ℃ forced air drying oven for keeping for 20 minutes, and finally washing the base membrane with water to obtain the polyamide hollow fiber nanofiltration composite membrane.
In this example, the bonding strength between the base film and the separation layer of the polyamide hollow fiber nanofiltration composite membrane obtained in the same manner as in example 1 was measured, and the test results were obtained: the salt rejection rate is changed from 94.9 percent to 93.8 percent, and the water flux is changed from 23.1L/m2h is changed to 24.5L/m2h。
Example 7
The embodiment provides a preparation method of a polyamide hollow fiber nanofiltration composite membrane, which comprises the following steps:
step 1: using polyamide hollow fiber ultrafiltration membrane as base membrane, and placing the base membrane into Na with concentration of 4% at 60 deg.C2CO3Performing hydrolysis activation treatment on the (sodium carbonate) solution for 1 hour, and cleaning the base membrane by using pure water until the pH value of the base membrane is neutral after the activation treatment is finished;
step 2: placing the base film into a polyethyleneimine water solution with the mass concentration of 1% for 5 minutes, wherein the weight-average molecular weight of the polyethyleneimine in the embodiment is 50000;
and step 3: taking out the base film from the polyethyleneimine aqueous solution, vertically hanging for 8 minutes, wiping off the redundant polyethyleneimine aqueous solution on the base film by using a paper towel, immersing the base film into a 0.5 mass percent trimesoyl chloride organic solution, and maintaining for 3 minutes to form a separation layer on the surface of the base film. The organic solvent in this example was heptane.
And 4, step 4: and taking the base membrane with the separation layer out of the trimesoyl chloride organic solution, putting the base membrane into an air-blast drying oven at the temperature of 80 ℃ for keeping for 20 minutes, and finally washing with water to obtain the polyamide hollow fiber nanofiltration composite membrane.
In this example, the bonding strength between the base film and the separation layer of the polyamide hollow fiber nanofiltration composite membrane obtained in the same manner as in example 1 was measured, and the test results were obtained: the desalination rate is changed from 90.4 percent to 89.4 percent, and the water flux is changed from 21.9L/m2h is changed to 27.4L/m2h。
The comparison of the control group with each example is shown in table 1:
TABLE 1
As can be seen from Table 1, the preparation method of the polyamide hollow fiber nanofiltration composite membrane adopted by the invention improves the adsorption uniformity of the surface of the base membrane, effectively reduces the structural defects of the membrane separation layer, enhances the connection tightness between the base membrane and the separation layer, and improves the service performance of the membrane
It will be apparent to those skilled in the art that various changes and modifications may be made in the invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (14)
1. A preparation method of a polyamide hollow fiber nanofiltration composite membrane is characterized by comprising the following steps:
step 1: activating the polyamide hollow fiber ultrafiltration membrane to form carboxylic acid groups and amino groups on the surface of the polyamide hollow fiber ultrafiltration membrane;
step 2: putting the polyamide hollow fiber ultrafiltration membrane subjected to activation treatment into polyamine aqueous solution;
and step 3: taking the polyamide hollow fiber ultrafiltration membrane out of the polyamine aqueous solution and putting the polyamide hollow fiber ultrafiltration membrane into a polybasic acyl chloride organic solution, wherein an interfacial polymerization reaction is generated on the surface of the polyamide hollow fiber ultrafiltration membrane to form a separation layer;
and 4, step 4: and taking the polyamide hollow fiber ultrafiltration membrane with the separation layer out of the polybasic acyl chloride organic solution and carrying out heat treatment on the polyamide hollow fiber ultrafiltration membrane to obtain the polyamide hollow fiber nanofiltration composite membrane.
2. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 1, wherein the activation treatment in the step 1 specifically comprises: putting the polyamide hollow fiber ultrafiltration membrane into an activating reagent for hydrolysis activation; and cleaning the polyamide hollow fiber ultrafiltration membrane until the pH value is neutral.
3. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 2, wherein the hydrolysis activation process comprises: the polyamide hollow fiber ultrafiltration membrane is kept in an activating reagent at the temperature of 30-80 ℃ for 30-90 minutes.
4. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 2 or 3, wherein the activation reagent is an alkaline activation reagent or an oxidative activation reagent at a mass concentration of 0.5% to 5%.
5. The method of claim 4, wherein the activating reagent comprises KOH, NaOH, Na2CO3And NaClO.
6. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 1, wherein the polyamine aqueous solution comprises a polyethyleneimine aqueous solution with a mass concentration of 0.1% to 1%.
7. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 6, wherein the mass concentration of the polyethyleneimine aqueous solution is 0.6-0.8%.
8. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to any one of claims 6 or 7, wherein the weight average molecular weight of the polyethyleneimine is 8000-50000.
9. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 1, wherein the poly-acyl chloride organic solution comprises 0.1 to 0.5 mass% of trimesoyl chloride organic solution.
10. The method of claim 1, wherein the organic solvent in the organic solution of polyacyl chloride comprises at least one of pentane, hexane, cyclohexane and heptane.
11. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 1, wherein the polyamide hollow fiber ultrafiltration membrane is placed in the polyamine aqueous solution for a retention time of 1 to 10 minutes in the step 2.
12. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 1, wherein the step 3 specifically comprises: taking the polyamide hollow fiber ultrafiltration membrane out of the polyamine aqueous solution, vertically suspending for 1-10 minutes, and wiping off the residual polyamine aqueous solution on the surface of the polyamide hollow fiber ultrafiltration membrane; placing the mixture into a polybasic acyl chloride organic solution for keeping for 1-5 minutes.
13. The method for preparing a polyamide hollow fiber nanofiltration composite membrane according to claim 1, wherein the heat treatment in the step 4 comprises: and (3) putting the polyamide hollow fiber ultrafiltration membrane into a drying oven at the temperature of 60-80 ℃ for 15-25 minutes.
14. A polyamide hollow fiber nanofiltration composite membrane, characterized by being prepared by the preparation method of any one of claims 1 to 13.
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| CN111974222A (en) * | 2020-08-25 | 2020-11-24 | 达拉特旗永胜污水处理有限公司 | Regeneration and restoration integration method for industrial waste reverse osmosis membrane |
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