CN115837223A - Composition for producing ultrafiltration and/or microfiltration membranes and method for producing composite ultrafiltration membranes - Google Patents
Composition for producing ultrafiltration and/or microfiltration membranes and method for producing composite ultrafiltration membranes Download PDFInfo
- Publication number
- CN115837223A CN115837223A CN202111101059.6A CN202111101059A CN115837223A CN 115837223 A CN115837223 A CN 115837223A CN 202111101059 A CN202111101059 A CN 202111101059A CN 115837223 A CN115837223 A CN 115837223A
- Authority
- CN
- China
- Prior art keywords
- membrane
- composition
- ultrafiltration
- ultrafiltration membrane
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to the field of material science, and discloses a composition for preparing an ultrafiltration and/or microfiltration membrane and a method for preparing a composite ultrafiltration membrane. In the composition provided by the invention, the polyvinyl alcohol and the hydrophilic porous material are adopted to carry out blending modification on the ultrafiltration and/or microfiltration membrane, and the dispersibility of the hydrophilic material and the compatibility between modified components such as the hydrophilic material and the membrane material are improved by utilizing the synergistic effect among the components, so that the composite ultrafiltration membrane prepared by the method provided by the invention has the advantages of good hydrophilicity, good pollution resistance effect and the like.
Description
Technical Field
The invention relates to the field of material science, in particular to a composition for preparing an ultrafiltration and/or microfiltration membrane and a method for preparing a composite ultrafiltration membrane.
Background
The membrane separation technology is widely applied to a plurality of fields of biology, medicine, environmental protection and the like, wherein in the water treatment work, the membrane separation technology becomes a research hotspot in the fields of materials and environmental protection at present due to the advantages of small occupied area, simple operation, high separation efficiency, good separation effect and the like. The common membrane separation sewage treatment method at present comprises ultrafiltration membrane separation, nanofiltration membrane separation, liquid membrane separation and the like, wherein the ultrafiltration membrane separation technology can effectively remove particulate matters, microorganisms, colloidal substances and other organic matters, and is an important technology in membrane separation water treatment application. However, the pollutants in the wastewater are adsorbed and deposited on the surface or in the pores of the membrane during the use process, so that the membrane pollution is caused, the service life of the membrane is shortened, and the membrane flux is continuously reduced along with the increase of the use time, so that the treatment effect is influenced. Therefore, improving the anti-fouling performance of ultrafiltration membranes has become a major research focus in membrane water treatment technology.
Researches show that the hydrophilicity of the membrane has a certain relation with pollution resistance, and the common methods for improving the hydrophilicity of the ultrafiltration membrane comprise surface modification and blending modification. The surface modification is realized by adopting a surface coating or grafting mode, so that the surface of the ultrafiltration membrane is covered with a hydrophilic layer, the hydrophilicity of the ultrafiltration membrane is improved, however, the hydrophilic coating on the surface of the modified ultrafiltration membrane obtained by the coating method is easy to fall off and has poor stability, the grafting method is complex in operation method, the grafting rate is difficult to control, and the stability of the product is also difficult to control. The blending modification is to mix the modified material directly in the film preparation process, and has the advantages of simple operation, low cost and stable modification effect. For example, CN105457510a discloses a hydrophilic polyethersulfone ultrafiltration membrane and a preparation method thereof, wherein polyethersulfone and hydrophilic polymer are blended and scraped, and then a cross-linking agent is grafted on the surface of the ultrafiltration membrane, thereby improving the hydrophilicity of the ultrafiltration membrane. CN102512998A discloses a preparation method of a molecular sieve modified polysulfone ultrafiltration membrane, which is characterized in that a molecular sieve and polysulfone are blended and then prepared into a microporous membrane by a phase inversion method, so that an ultrafiltration membrane with good hydrophilicity is obtained. However, the anti-pollution capability of the ultrafiltration membranes prepared by the blending modification is limited at present, and the hydrophilicity of the ultrafiltration membranes is still to be further improved.
Disclosure of Invention
The invention aims to overcome the problems of the prior art that the anti-pollution effect of an ultrafiltration membrane is not ideal, the hydrophilicity needs to be improved and the like, and provides a composition for preparing an ultrafiltration and/or microfiltration membrane and a method for preparing a composite ultrafiltration membrane. The composite ultrafiltration membrane provided by the invention has the advantages of good hydrophilicity, good pollution resistance effect, high mechanical strength and the like.
In order to achieve the above objects, in one aspect, the present invention provides a composition for preparing an ultrafiltration and/or microfiltration membrane, comprising, based on the total weight of the composition: 10-20 wt% of membrane material, 0.5-5 wt% of polyvinyl alcohol, 0.5-5 wt% of porous material and 5-15 wt% of additive.
The invention provides a method for preparing a composite ultrafiltration membrane, which comprises the steps of mixing the composition to prepare a membrane casting solution, preparing a semi-finished ultrafiltration membrane by adopting a membrane scraping mode, putting the semi-finished ultrafiltration membrane into a coagulating bath for immersion precipitation phase inversion membrane preparation, and then performing desolventizing and pore-protecting treatment to obtain the composite ultrafiltration membrane.
A third aspect of the invention provides a composite ultrafiltration membrane prepared according to the method described above.
Through the technical scheme, the invention can obtain the following beneficial effects:
(1) According to the composite ultrafiltration membrane provided by the invention, the polyvinyl alcohol and the hydrophilic porous material are adopted to carry out blending modification on the ultrafiltration membrane, and the synergistic effect among all the components, particularly the synergistic effect among the polyvinyl alcohol and the hydrophilic porous material is utilized, so that the hydrophilicity and the anti-pollution performance of the ultrafiltration membrane are improved, the compatibility between the hydrophilic material and the membrane material is improved, the dispersity of all the components (particularly the hydrophilic material) in the membrane casting solution is improved, and the hydrophilicity and the anti-pollution performance of the ultrafiltration membrane are better and more stable.
(2) The porous material in the composite ultrafiltration membrane provided by the invention not only influences the permeability of the ultrafiltration membrane through the pore structure of the porous material, but also increases the mechanical strength and the mechanical stability of the ultrafiltration membrane, so that the composite ultrafiltration membrane is more durable and has longer service life.
(3) The cross-linking agent is added in the preparation process of the composite ultrafiltration membrane provided by the invention, and the polyvinyl alcohol is chemically cross-linked while the composite ultrafiltration membrane is phase-separated to form a membrane, so that the water resistance of the composite ultrafiltration membrane is improved, and the service life of the composite ultrafiltration membrane is further prolonged.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The inventor of the invention skillfully discovers that when the ultrafiltration membrane is prepared by adopting a blending method, the addition of the porous material and the polyvinyl alcohol can improve the hydrophilicity and the pollution resistance of the ultrafiltration membrane, and the compatibility and the dispersibility of the porous material in a membrane matrix are also better. And the anti-pollution property and the mechanical stability of the ultrafiltration membrane can be further improved by selecting and optimizing the content of each component.
In one aspect, the present invention provides a composition for preparing an ultrafiltration and/or microfiltration membrane, comprising, based on the total weight of the composition: 10-20 wt% of membrane material, 0.5-5 wt% of polyvinyl alcohol, 0.5-5 wt% of porous material and 5-15 wt% of additive. The "ultrafiltration and/or microfiltration membrane" may be any form of membrane material known in the art for use in ultrafiltration or microfiltration processes, e.g. may be a (flat) ultrafiltration membrane, a hollow fibre membrane, etc.
The porous material employed in the compositions provided herein can be any of the hydrophilic porous materials currently used in the art for the preparation of ultrafiltration and/or microfiltration membranes. According to a preferred embodiment of the present invention, wherein the porous material is at least one selected from the group consisting of a microporous molecular sieve, a mesoporous inorganic material, and an organic framework material.
In order to secure the mechanical properties of the membrane while obtaining good hydrophilicity, it is preferable that the particle size of the porous material is 0.1 to 1 μm.
Any microporous molecular sieve having the above particle size may be suitable for use in the present invention. Preferably, the microporous molecular sieve is selected from microporous zeolitic molecular sieves. Any microporous zeolite molecular sieve known in the art that can be used in ultrafiltration and/or microfiltration membrane preparation may be suitable for use in the present invention, such as 4A molecular sieves, ZSM-5 molecular sieves, Y-type molecular sieves, and the like.
Any mesoporous inorganic material having the above-described particle size and pore structure characteristics may be suitable for use in the present invention. Preferably, the mesoporous inorganic material is selected from mesoporous carbon and/or mesoporous SiO 2 。
Any organic framework material having the above-described particle size and pore structure characteristics may be suitable for use in the present invention. Preferably, the organic framework material is selected from metal organic framework Materials (MOFs) and/or covalent organic framework materials (COFs).
Any metal organic framework material that can be used in the art for ultrafiltration and/or microfiltration membrane preparation can be suitable for use in the present invention. Such as ZIFs series metal organic framework materials, uiO series metal organic framework materials and the like.
Any covalent organic framework material that can be used in the art for ultrafiltration and/or microfiltration membrane preparation can be suitable for use in the present invention. For example, tpPa-1, tpPa-2, etc.
According to a preferred embodiment of the invention, wherein the additive comprises an organic additive and/or an inorganic additive.
In the invention, the additive is used for improving the interaction of the components in the composition and reducing the solvation effect in a polymer solution, thereby effectively adjusting the characteristics of the membrane such as pore diameter, porosity, hydrophilicity and the like. Any organic and/or inorganic additive capable of performing the above-described functions may be suitable for use in the present invention.
Preferably, the organic additive is selected from at least one of polyethylene glycol, ethyl acetate, polymaleic anhydride, cyclohexanol, glycerol, triethyl phosphate, tributyl phosphate, polyvinylpyrrolidone.
Preferably, the inorganic additive is selected from at least one of sodium chloride, lithium chloride, calcium chloride, lithium nitrate, calcium nitrate, magnesium chloride, and zinc chloride.
Any polyvinyl alcohol known in the art for use in ultrafiltration and/or microfiltration (hydrophilic) modification may be suitable for use in the present invention. According to a preferred embodiment of the present invention, wherein the weight average molecular weight of the polyvinyl alcohol is 100000-200000;
preferably, the alcoholysis degree of the polyvinyl alcohol is more than 85%.
Any membrane material known in the art for use in ultrafiltration and/or microfiltration membrane preparation may be suitable for use in the present invention. Preferably, the membrane material is selected from at least one of polysulfone, polyethersulfone (preferably polyethersulfone with weight average molecular weight of 40000-60000) and fluoropolymer (such as polyvinylidene fluoride and the like, preferably polyvinylidene fluoride with weight average molecular weight of 300000-450000).
The present invention also provides a composition comprising a solvent, wherein the solvent is present in an amount of 60 to 80 wt% based on the total weight of the composition, in order to optimize the structure and properties of a film made using the composition, according to a preferred embodiment of the present invention.
Any solvent known in the art for use in the preparation of ultrafiltration and/or microfiltration membranes may be suitable for use in the compositions provided herein. According to a preferred embodiment of the present invention, wherein the solvent is at least one selected from the group consisting of dimethylformamide, dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone.
According to a preferred embodiment of the present invention, the composition further comprises a crosslinking agent independently present. Preferably, the cross-linking agent is glutaraldehyde. By "independent" is meant that the crosslinking agent is packaged and used separately from the composition described above.
Ultrafiltration and/or microfiltration membranes prepared using the compositions as described above are also within the scope of the present invention.
The invention provides a method for preparing a composite ultrafiltration membrane, which comprises the steps of mixing the composition to prepare a membrane casting solution, preparing a semi-finished ultrafiltration membrane by adopting a membrane scraping mode, putting the semi-finished ultrafiltration membrane into a coagulating bath for immersion precipitation phase inversion membrane preparation, and then performing desolventizing and pore-protecting treatment to obtain the composite ultrafiltration membrane.
According to a preferred embodiment of the present invention, wherein the mixing conditions include: the temperature is 80-100 ℃, the stirring speed is 150-400rpm, and the time is 12-24h.
According to a preferred embodiment of the present invention, the casting solution is further subjected to defoaming and homogenizing treatment before the membrane scraping.
Any defoaming means currently used in the art for ultrafiltration membrane preparation can be applied to the methods provided herein. Preferably, the defoaming means comprises: standing at 20-30 deg.C for 12-24 hr.
Any homogenization method known in the art for enhancing the dispersion and compatibility of the components in a mixture, particularly a membrane casting solution for ultrafiltration membranes, may be suitable for use in the present invention. Preferably, the homogenizing comprises: the temperature is 20-30 ℃, and the ultrasonic treatment is carried out for 2-6h.
According to a preferred embodiment of the present invention, the coagulation bath contains a crosslinking agent.
Preferably, the cross-linking agent is selected from glutaraldehyde.
More preferably, the coagulation bath is performed using a mixed aqueous solution of hydrochloric acid and glutaraldehyde, wherein the concentration of HCl in the mixed aqueous solution is 0.015 to 0.045M and the concentration of glutaraldehyde is 2 to 5 wt%.
According to a preferred embodiment of the present invention, wherein the condition of the wiping film includes: the temperature is 20-30 ℃, the film scraping speed is 5-15cm/s, and the film scraping thickness is 100-250 mu m.
According to a preferred embodiment of the present invention, the method for preparing a membrane by immersion precipitation phase inversion comprises: immersing the film scraping product in a coagulating bath at the temperature of 20-60 ℃ and standing for 0.5-3h.
Any desolventizing treatment method for ultrafiltration membrane preparation known in the art may be applied to the method provided by the present invention. According to a preferred embodiment of the present invention, wherein the solvent removing means comprises: standing and soaking in water at 20-30 deg.C for 24-72 hr.
Any conventional pore-preserving treatment means used in the art for ultrafiltration membrane preparation can be adapted for use in the methods provided herein.
In a third aspect, the present invention provides a composite ultrafiltration membrane prepared by the method described above.
In addition, the invention also provides application of the composite ultrafiltration membrane in sewage treatment. For example, in the treatment of domestic sewage, industrial sewage and other sewage.
The present invention will be described in detail below by way of examples. It should be understood that the following examples are only intended to further illustrate and explain the contents of the present invention by way of example, and are not intended to limit the present invention.
In the following examples, the polyvinyl alcohol had a weight average molecular weight of 145000 and an alcoholysis degree of 98. + -. 1%. Unless otherwise specified, all other chemicals used were purchased from the normal chemical suppliers and were of analytical purity.
In the following examples, the specific method of the hole-protecting treatment is: soaking the mixture in 0.2wt% sodium dodecyl sulfate for 5-6 days, and drying at room temperature and humidity of 88%.
In the following examples, all operations were carried out at room temperature (25. + -. 5 ℃ C.) unless otherwise specified.
Example 1
(1) Preparation of casting solution
The components are as follows: 15 wt% polyethersulfone (weight average molecular weight 58000), 1 wt% polyvinyl alcohol, 0.5 wt% 4A molecular sieve (particle size 500 nm), 10 wt% polyethylene glycol (PEG 400), 73.5 wt% dimethylsulfoxide.
The above components were mixed and heated to 80 ℃ and stirred at 200rpm for 24h. Standing for 24h for defoaming, and then carrying out ultrasonic treatment for 2h to obtain a casting solution-1.
(2) Scraping film
And (3) uniformly coating the membrane casting solution-1 on a glass plate by using a scraper, wherein the membrane scraping speed is 15cm/s, and the membrane scraping thickness is 150 mu m, so as to obtain a semi-finished ultrafiltration membrane-1.
(3) Solidification film-making, desolventizing and hole-protecting treatment
Coagulation bath-1: an aqueous solution of HCl mixed with glutaraldehyde at an HCl concentration of 0.02M and at a glutaraldehyde concentration of 4 wt.%.
And (3) placing the semi-finished ultrafiltration membrane-1 in a coagulating bath-1, and soaking and coagulating at 20 ℃ for 3h. And then placing the semi-finished product-1 of the solidified ultrafiltration membrane in deionized water for soaking for 72h for desolvation treatment, and then carrying out pore-protecting treatment to obtain the composite ultrafiltration membrane A1.
Example 2
(1) Preparation of casting solution
The components are as follows: 18% by weight of polyethersulfone (weight-average molecular weight 58000), 1% by weight of polyvinyl alcohol, 1% by weight of 4A molecular sieve (particle size 500 nm), 5% by weight of polyethylene glycol (PEG 400), 75% by weight of dimethylsulfoxide.
The above components were mixed and heated to 80 ℃ and stirred at 300rpm for 12h. Standing for 24h for defoaming, and then carrying out ultrasonic treatment for 4h to obtain a casting solution-2.
(2) Scraping film
And (3) uniformly coating the membrane casting solution-2 on a glass plate by using a scraper, wherein the membrane scraping speed is 10cm/s, and the membrane scraping thickness is 150 mu m, so as to obtain a semi-finished ultrafiltration membrane-2.
(3) Solidification film-making, desolventizing and hole-protecting treatment
Coagulation bath-2: HCl and glutaraldehyde were mixed in an aqueous solution with an HCl concentration of 0.015M and a glutaraldehyde concentration of 2% by weight.
And (3) placing the semi-finished ultrafiltration membrane-2 in a coagulating bath-2, and soaking and coagulating for 2h at 40 ℃. And then placing the solidified ultrafiltration membrane semi-finished product-2 in deionized water for soaking for 72h for solvent removal treatment, and then performing pore protection treatment to obtain the composite ultrafiltration membrane A2.
Example 3
The components are as follows: 15 wt% of polyethersulfone (weight-average molecular weight of 58000), 1 wt% of polyvinyl alcohol, 0.5 wt% of mesoporous SiO 2 (particle size 200 nm), 10% by weight of glycerol, 73.5% by weight of dimethyl sulfoxide.
The above components were mixed and heated to 80 ℃ and stirred at 300rpm for 24h. Standing for 12h for defoaming, and then carrying out ultrasonic treatment for 6h to obtain a casting solution-3.
(2) Scraping film
And (3) uniformly coating the membrane casting solution-3 on a glass plate by using a scraper, wherein the membrane scraping speed is 10cm/s, and the membrane scraping thickness is 150 mu m, so as to obtain a semi-finished ultrafiltration membrane-3.
(3) Solidification film-making, desolventizing and hole-protecting treatment
The coagulation bath-2 in example 2 was used to form a film by coagulation.
And (3) placing the semi-finished ultrafiltration membrane-3 in a coagulating bath-2, and soaking and coagulating at 60 ℃ for 1h. And then placing the solidified ultrafiltration membrane semi-finished product-3 in deionized water for soaking for 36h for solvent removal treatment, and then performing pore protection treatment to obtain the composite ultrafiltration membrane A3.
Example 4
The components are as follows: 15 wt% polyvinylidene fluoride (weight average molecular weight 400000), 2wt% polyvinyl alcohol, 1 wt% mesoporous carbon (particle size 100 nm), 10 wt% polyethylene glycol (PEG 400), 72 wt% dimethyl sulfoxide.
The above components were mixed and heated to 90 ℃ and stirred at 350rpm for 18h. Standing for 12h for defoaming, and then carrying out ultrasonic treatment for 2h to obtain a casting solution-4.
(2) Scraping film
And (3) uniformly coating the membrane casting solution-4 on a glass plate by using a scraper, wherein the membrane scraping speed is 5cm/s, and the membrane scraping thickness is 100 mu m, so as to obtain a semi-finished ultrafiltration membrane-4.
(3) Solidification film-making, desolventizing and hole-protecting treatment
Coagulation bath-3: HCl and glutaraldehyde were mixed in an aqueous solution with an HCl concentration of 0.02M and a glutaraldehyde concentration of 2% by weight.
And (3) placing the semi-finished ultrafiltration membrane-4 in a coagulating bath-3, and soaking and coagulating at 60 ℃ for 0.5h. And then placing the solidified ultrafiltration membrane semi-finished product-4 in deionized water for soaking for 24 hours for desolventizing treatment, and then performing hole retention treatment to obtain the composite ultrafiltration membrane A4.
Example 5
The components are as follows: 20% by weight of polyethersulfone (weight-average molecular weight 58000), 0.5% by weight of polyvinyl alcohol, 0.5% by weight of 4A molecular sieve (particle size 500 nm), 10% by weight of polyvinylpyrrolidone (PVP K30), 69% by weight of dimethylsulfoxide.
The components are mixed and heated to 80 ℃ and stirred at 350rpm for 24h. Standing for 24h for defoaming, and then carrying out ultrasonic treatment for 2h to obtain a casting solution-5.
(2) Scraping film
And uniformly coating the membrane casting solution-5 on a glass plate by using a scraper, wherein the membrane scraping speed is 15cm/s, and the membrane scraping thickness is 150 mu m, so as to obtain a semi-finished product-5 of the ultrafiltration membrane.
(3) Solidification film-making, desolventizing and hole-protecting treatment
Coagulation bath-4: HCl and glutaraldehyde were mixed in an aqueous solution with an HCl concentration of 0.03M and a glutaraldehyde concentration of 4% by weight.
Placing the semi-finished ultrafiltration membrane-5 in a coagulating bath-4, and soaking and coagulating at 20 deg.C for 3h. And then placing the solidified ultrafiltration membrane semi-finished product-5 in deionized water for soaking for 48h for solvent removal treatment, and then performing pore protection treatment to obtain the composite ultrafiltration membrane A5.
Example 6
The components are as follows: 20% by weight of polyethersulfone (weight-average molecular weight 58000), 0.5% by weight of polyvinyl alcohol, 0.5% by weight of UiO-66 (average particle diameter 400 nm), 10% by weight of polyvinylpyrrolidone (PVP K30), 69% by weight of dimethylacetamide.
The above components were mixed and heated to 80 ℃ and stirred at 300rpm for 24h. Standing for 24h for defoaming, and then carrying out ultrasonic treatment for 2h to obtain a casting solution-6.
(2) Scraping film
And (3) uniformly coating the membrane casting solution-6 on a glass plate by using a scraper, wherein the membrane scraping speed is 15cm/s, and the membrane scraping thickness is 150 mu m, so as to obtain a semi-finished ultrafiltration membrane-6.
(3) Solidification film-making, desolventizing and hole-protecting treatment
The coagulation bath-3 in example 4 was used to form a film by coagulation.
Placing the semi-finished ultrafiltration membrane-6 in a coagulating bath-3, and soaking and coagulating at 20 deg.C for 3h. And then placing the solidified ultrafiltration membrane semi-finished product-6 in deionized water for soaking for 72h for solvent removal treatment, and then performing pore protection treatment to obtain the composite ultrafiltration membrane A6.
Example 7
The components are as follows: 20% by weight of polyethersulfone (weight-average molecular weight 58000), 0.5% by weight of polyvinyl alcohol, 0.5% by weight of 4A molecular sieve (particle size 500 nm), 10% by weight of lithium chloride, 69% by weight of dimethylsulfoxide.
The above components were mixed and heated to 90 ℃ and stirred at 250rpm for 24h. Standing for 12h for defoaming, and then carrying out ultrasonic treatment for 4h to obtain a casting solution-7.
(2) Scraping film
And (3) uniformly coating the membrane casting solution-7 on a glass plate by using a scraper, wherein the membrane scraping speed is 5cm/s, and the membrane scraping thickness is 100 mu m, so as to obtain a semi-finished ultrafiltration membrane-7.
(3) Solidification film-making, desolventizing and hole-protecting treatment
The coagulation bath-2 in example 2 was used to form a film by coagulation.
Placing the semi-finished ultrafiltration membrane-7 in a coagulating bath-2, and soaking and coagulating at 20 deg.C for 3h. And then placing the semi-finished product-7 of the solidified ultrafiltration membrane in deionized water for soaking for 72h for desolvation treatment, and then carrying out pore-protecting treatment to obtain the composite ultrafiltration membrane A7.
Example 8
The components are as follows: 18% by weight of polyethersulfone (weight-average molecular weight 58000), 1% by weight of polyvinyl alcohol, 1% by weight of COF-TpPa-1 (particle size 1 μm), 5% by weight of polyethylene glycol (PEG 400), 75% by weight of dimethylsulfoxide.
After mixing the components, the mixture is heated to 80 ℃ and stirred for 12 hours at 300 rpm. Standing for 24h for defoaming, and then carrying out ultrasonic treatment for 4h to obtain a casting solution-8.
(2) Scraping film
And uniformly coating the membrane casting solution-8 on a glass plate by using a scraper, wherein the membrane scraping speed is 10cm/s, and the membrane scraping thickness is 150 mu m, so as to obtain a semi-finished product-8 of the ultrafiltration membrane.
(3) Solidification film-making, desolventizing and hole-protecting treatment
Coagulation bath-5: HCl and glutaraldehyde were mixed in an aqueous solution with an HCl concentration of 0.04M and a glutaraldehyde concentration of 2% by weight.
And (3) placing the semi-finished ultrafiltration membrane-8 in a coagulating bath-5, and soaking and coagulating for 2h at 40 ℃. And then placing the solidified ultrafiltration membrane semi-finished product-8 in deionized water for soaking for 72h for solvent removal treatment, and then performing pore protection treatment to obtain the composite ultrafiltration membrane A8.
Example 9
The components are as follows: 15% by weight of polyethersulfone (weight-average molecular weight 58000), 1.5% by weight of polyvinyl alcohol, 0.5% by weight of 4A molecular sieve (particle size 500 nm), 10% by weight of magnesium chloride, 73% by weight of dimethylsulfoxide.
The above components were mixed and heated to 80 ℃ and stirred at 200rpm for 24h. Standing for 24h for defoaming, and then carrying out ultrasonic treatment for 2h to obtain a casting solution-9.
(2) Scraping film
And (3) uniformly coating the membrane casting solution-9 on a glass plate by using a scraper, wherein the membrane scraping speed is 15cm/s, and the membrane scraping thickness is 150 mu m, so as to obtain a semi-finished ultrafiltration membrane-9.
(3) Solidification film-making, desolventizing and hole-protecting treatment
Coagulation bath-6: HCl and glutaraldehyde were mixed in an aqueous solution with an HCl concentration of 0.04M and a glutaraldehyde concentration of 4% by weight.
Placing the semi-finished product-9 of the ultrafiltration membrane in a coagulating bath-6, and soaking and coagulating at 20 ℃ for 3h. And then placing the solidified ultrafiltration membrane semi-finished product-9 in deionized water for soaking for 72h for solvent removal treatment, and then performing pore protection treatment to obtain the composite ultrafiltration membrane A9.
Example 10
The method of example 1 was used except that glutaraldehyde was not added to the coagulation bath but the HCl concentration was maintained the same as in coagulation bath-1. The remaining steps and conditions were the same as in example 1. Obtaining the composite ultrafiltration membrane A10.
Comparative example 1
The method of example 1 was used except that the polyvinyl alcohol content in the casting solution was adjusted to 10% by weight and the dimethyl sulfoxide content was adjusted to 64.5% by weight. The remaining steps and conditions were the same as in example 1. Obtaining the composite ultrafiltration membrane D1.
Comparative example 2
The method of example 1 was used except that the 4A molecular sieve was replaced with nano SiO 2 (particle size 500 nm). The remaining steps and conditions were the same as in example 1. Obtaining the composite ultrafiltration membrane D2.
Comparative example 3
The method of example 1 was used except that the 4A molecular sieve was not added and the content of dimethyl sulfoxide in the casting solution was adjusted to 74% by weight. The remaining steps and conditions were the same as in example 1.
Obtaining the composite ultrafiltration membrane D3.
Comparative example 4
The method of example 1 was used except that polyvinyl alcohol was not added and the content of dimethyl sulfoxide in the casting solution was adjusted to 74.5 wt%. The remaining steps and conditions were the same as in example 1. Obtaining the composite ultrafiltration membrane D4.
Test example 1
The performance of the composite ultrafiltration membranes obtained in the above examples and comparative examples was examined by the following methods, respectively. The results are detailed in table 1.
(1) Tensile strength: the stretching rate was 40mm/min as measured by an electronic stretcher (Instron 3342, USA).
(2) Water contact angle: measured by a contact angle measuring instrument (easy drop Standard, KRUSS, germany), in which the ambient temperature is controlled to 20 ℃ ± 5 ℃, and 5 different test points are taken from each film sheet to test the contact angle and averaged.
(3) And (3) testing water resistance: after soaking the membrane in deionized water for 72 hours (changing the deionized water every 12 hours), the membrane was removed and rinsed, dried at room temperature, and its contact angle was measured. The water resistance of the membrane is judged by comparing the change of the initial contact angle and the contact angle value after soaking, and the water resistance is poorer when the change is larger.
(4) Pure water flux: adopting cup ultrafiltration system to carry out pure water flux test, pressure drive adopts high-purity nitrogen gas, and the driving pressure is 0.1MPa, adopts electronic balance on-line continuous monitoring to pass through water accumulation volume change, calculates the water flux J of membrane according to the following formula:
wherein V is the volume of the permeate; a is the effective area of membrane filtration; t is the filtration time.
TABLE 1
As can be seen from the data in Table 1, the ultrafiltration membranes prepared by the composition and the method provided by the invention have better hydrophilicity and higher flux and strength, and the water resistance and stability of the ultrafiltration membranes are stronger as shown by comparing the initial water contact angle with the water contact angle after soaking for 72 hours by using deionized water. Therefore, the service life of the ultrafiltration membrane provided by the invention can be effectively prolonged.
By comparing the detection results of the ultrafiltration membranes A1 and A10, the water resistance of the ultrafiltration membranes can be remarkably improved after the cross-linking agent is added into the coagulation bath. On the other hand, comparing the results of the ultrafiltration membranes A1 and D1-D4, it can be seen that when any one of the components of the composition provided by the present invention is missing or some other component is replaced by another material not preferred by the present invention, the performance of the ultrafiltration membrane made from the composition is deteriorated.
In addition, the phenomenon that modified components are agglomerated is hardly observed in the membrane casting solution adopted in the preparation process of the ultrafiltration membranes A1-A10, which shows that the uniformity of the membrane casting solution is better when the composition provided by the invention is used for preparing the ultrafiltration membranes. When the ultrafiltration membrane D4 is prepared, obvious agglomeration of the modified components can be observed in the membrane casting solution, which indicates that the modified components are not well compatible with the membrane matrix, and the membrane casting solution has uneven component distribution.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A composition for use in the preparation of an ultrafiltration and/or microfiltration membrane comprising, based on the total weight of the composition: 10-20 wt% of membrane material, 0.5-5 wt% of polyvinyl alcohol, 0.5-5 wt% of porous material and 5-15 wt% of additive.
2. The composition of claim 1, wherein the porous material is selected from at least one of a microporous molecular sieve, a mesoporous inorganic material, and an organic framework material;
preferably, the particle size of the porous material is 0.1-1 μm;
preferably, the microporous molecular sieve is selected from microporous zeolitic molecular sieves;
preferably, the mesoporous inorganic material is selected from mesoporous carbon and/or mesoporous SiO 2 ；
Preferably, the organic framework material is selected from a metal-organic framework material and/or a covalent organic framework material.
3. The composition of claim 1, wherein the additive comprises an organic additive and/or an inorganic additive;
preferably, the organic additive is selected from at least one of polyethylene glycol, ethyl acetate, polymaleic anhydride, cyclohexanol, glycerol, triethyl phosphate, tributyl phosphate, polyvinylpyrrolidone;
preferably, the inorganic additive is selected from at least one of sodium chloride, lithium chloride, calcium chloride, lithium nitrate, calcium nitrate, magnesium chloride, and zinc chloride.
4. The composition of claim 1, wherein the polyvinyl alcohol has a weight average molecular weight of 100000-200000;
preferably, the alcoholysis degree of the polyvinyl alcohol is more than 85%.
5. The composition of claim 1, wherein the membrane material is selected from at least one of polysulfone, polyethersulfone, and fluoropolymer;
and/or, the composition also comprises a solvent, preferably the content of the solvent is 60-80 wt% of the total weight of the composition;
preferably, the solvent is selected from at least one of dimethylformamide, dimethylacetamide, dimethylsulfoxide, and N-methylpyrrolidone.
6. The composition according to any one of claims 1 to 5, wherein the composition further comprises a separate cross-linking agent, preferably glutaraldehyde.
7. A method for preparing a composite ultrafiltration membrane is characterized by comprising the steps of mixing the composition of any one of claims 1 to 5 to prepare a membrane casting solution, then preparing a semi-finished ultrafiltration membrane by adopting a membrane scraping mode, then placing the semi-finished ultrafiltration membrane in a coagulating bath for immersion precipitation phase inversion membrane preparation, and then performing desolventizing and pore-protecting treatment to obtain the composite ultrafiltration membrane.
8. The method of claim 7, wherein the conditions of mixing comprise: the temperature is 80-100 ℃, the stirring speed is 150-400rpm, and the time is 12-24h;
and/or the condition of the scraping film comprises: the temperature is 20-30 ℃, the film scraping speed is 5-15cm/s, and the film scraping thickness is 100-250 mu m;
and/or the immersion precipitation phase inversion membrane preparation mode comprises the following steps: immersing the film scraping product in a coagulating bath, and standing for 0.5-3h at the temperature of 20-60 ℃;
and/or, the solvent removing mode comprises the following steps: standing and soaking in water at 20-30 deg.C for 24-72 hr.
9. The method of claim 7, wherein the coagulation bath contains a cross-linking agent;
preferably, the cross-linking agent is selected from glutaraldehyde;
more preferably, the coagulating bath adopts a mixed aqueous solution of hydrochloric acid and glutaraldehyde, wherein the concentration of HCl in the mixed aqueous solution is 0.015-0.045M, and the concentration of glutaraldehyde is 2-5 wt%.
10. A composite ultrafiltration membrane prepared according to the method of any one of claims 7 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111101059.6A CN115837223A (en) | 2021-09-18 | 2021-09-18 | Composition for producing ultrafiltration and/or microfiltration membranes and method for producing composite ultrafiltration membranes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111101059.6A CN115837223A (en) | 2021-09-18 | 2021-09-18 | Composition for producing ultrafiltration and/or microfiltration membranes and method for producing composite ultrafiltration membranes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115837223A true CN115837223A (en) | 2023-03-24 |
Family
ID=85574284
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111101059.6A Pending CN115837223A (en) | 2021-09-18 | 2021-09-18 | Composition for producing ultrafiltration and/or microfiltration membranes and method for producing composite ultrafiltration membranes |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115837223A (en) |
-
2021
- 2021-09-18 CN CN202111101059.6A patent/CN115837223A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109847586B (en) | High-flux reverse osmosis membrane and preparation method and application thereof | |
| Han et al. | Preparation and characterization of cellulose acetate/carboxymethyl cellulose acetate blend ultrafiltration membranes | |
| CN102794116B (en) | Mesoporous silicon dioxide sphere-polymer nano composite nano-filtration membrane and preparation method thereof | |
| JP3174332B2 (en) | Hydrophilic membrane made from polyethersulfone / poly-2-oxazoline / polyvinylpyrrolidone blend | |
| Song et al. | Characteristics of ultrafiltration membranes fabricated from polysulfone and polymer-grafted silica nanoparticles: Effects of the particle size and grafted polymer on the membrane performance | |
| CN107126849B (en) | Preparation method of hydrophilized polyvinylidene fluoride hybrid membrane | |
| CN108993171B (en) | Application of attapulgite in improving filtering flux of polyvinylidene fluoride ultrafiltration membrane | |
| WO2018201924A1 (en) | Composite reverse osmosis membrane, and manufacturing method thereof | |
| CN111760461B (en) | Preparation method of polyvinylidene fluoride mixed matrix membrane | |
| EP2060315A2 (en) | High performance membrane | |
| CN107149882A (en) | A kind of Kynoar pollution-resistant membrane and preparation method thereof | |
| WO2010078721A1 (en) | Modification method of interpenetrating polymer network on surface of porous polyvinylidene fluoride membrane | |
| CN111495206B (en) | Preparation method of high-flux pressure-resistant ultrafiltration membrane | |
| CN110479109B (en) | Preparation method of polyvinylidene fluoride mixed matrix membrane with high flux and strong pollution resistance | |
| CN106215724A (en) | A kind of antibacterial composite nanometer filtering film of loading nano silvery and preparation method thereof | |
| CN110743376A (en) | Novel PVDF-COF-MOFs ternary matrix mixed film and preparation method thereof | |
| CN109351190A (en) | It is a kind of to be crosslinked the compound solvent resistant nanofiltration membrane of fluorine-containing polyamide, preparation method and applications | |
| WO2005014150A1 (en) | Pvc hollow filtration membrane and the preparation method thereof | |
| Tang et al. | Effect of ethanol in the coagulation bath on the structure and performance of PVDF‐g‐PEGMA/PVDF membrane | |
| CN110917905B (en) | Ultrafiltration membrane and preparation method thereof | |
| CN113019157B (en) | Multifunctional supported nano multilayer composite film and preparation method and application thereof | |
| CN110605028A (en) | Preparation method of polyvinylidene fluoride mixed matrix membrane with high mechanical strength | |
| CN107088367B (en) | Preparation method of anti-pollution PVDF (polyvinylidene fluoride) hybrid membrane | |
| CN108499374A (en) | PVDF composite graphites alkene filter core film and its production technology | |
| CN110947308B (en) | Method for preparing composite reverse osmosis membrane by using GO/ZnO |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |