阅读说明：本技术 一种高效防污、亲水的聚醚砜超滤膜及其制备方法 (Efficient antifouling hydrophilic polyethersulfone ultrafiltration membrane and preparation method thereof ) 是由 李勇进 倪春军 郑鑫 于 2019-11-05 设计创作，主要内容包括：本发明公开一种高效防污、亲水的聚醚砜超滤膜及其制备方法。本发明通过Co-γ辐射接枝的化学改性方法,在聚醚砜表面均匀分布化学键连接的含不饱和键的离子液体,然后通过浸没沉淀相转化方法制备得到不对称多孔膜；离子液体与聚醚砜的质量比为2～11：100。本发明为不对称多孔膜,表现出优异的防污性能,较好的纯水通量和BSA截留率。(The invention discloses a high-efficiency antifouling hydrophilic polyethersulfone ultrafiltration membrane and a preparation method thereof. According to the preparation method, by a chemical modification method of Co-gamma radiation grafting, ionic liquid containing unsaturated bonds and connected by chemical bonds is uniformly distributed on the surface of polyether sulfone, and then the asymmetric porous membrane is prepared by an immersion precipitation phase conversion method; the mass ratio of the ionic liquid to the polyether sulfone is 2-11: 100. the invention is an asymmetric porous membrane, which shows excellent antifouling performance, better pure water flux and BSA retention rate.)

1. An efficient antifouling hydrophilic polyethersulfone ultrafiltration membrane is characterized in that ionic liquid connected with chemical bonds is uniformly distributed on the surface of a polyethersulfone material by a chemical modification method of Co-gamma radiation grafting, and then an asymmetric porous membrane is prepared by an immersion precipitation phase conversion method; the mass ratio of the ionic liquid to the polyether sulfone is (2-11): 100, respectively;

the Ionic Liquid (IL) is an ionic liquid containing unsaturated bonds.

2. A preparation method of a high-efficiency antifouling hydrophilic polyethersulfone ultrafiltration membrane is characterized by comprising the following steps:

adding PES and ionic liquid into a reaction kettle according to a certain proportion to carry out solution blending; wherein the mass ratio of the ionic liquid to the PES is 2-11: 100, respectively;

the ionic liquid is an ionic liquid containing unsaturated bonds;

step (2), spreading a film on the solution after the solution blending, and drying to remove the solvent to obtain a polymer and ionic liquid blended film;

step (3), placing the obtained blend film in a polyethylene plastic bag for radiation irradiation;

the irradiation is Co-gamma ray irradiation, and the experimental conditions are normal temperature and air or nitrogen environment;

and (4) preparing the irradiated polymer into a solution, and performing membrane casting by using an immersion precipitation phase conversion method to obtain the multifunctional PES porous membrane.

3. The high-efficiency antifouling hydrophilic polyethersulfone ultrafiltration membrane according to claim 1 or the high-efficiency antifouling hydrophilic polyethersulfone ultrafiltration membrane prepared by the preparation method according to claim 2, wherein the ionic liquid containing unsaturated bonds is imidazole ionic liquid;

the cation structural formula is as follows:

wherein R1 is C1-C24 alkyl or C2-C24 alkenyl; r2 is alkenyl containing C2-C24;

the anion is PF₆ ^-、BF₄ ^-、Br^-、Cl^-、I^-、NO₃ ^-、CF₃CO₂ ^-、CH₃COO^-Or (CF)₃SO₃)₂N^-。

4. The high-efficiency antifouling hydrophilic polyethersulfone ultrafiltration membrane according to claim 1 or the preparation method according to claim 2, wherein the Co-gamma irradiation absorption dose is 30 kGy.

5. The method for preparing a permanent antibacterial polyethersulfone film material as claimed in claim 2, wherein the temperature in the solution blending process in step (1) is 60 ℃.

6. The method for preparing a permanent antibacterial polyethersulfone membrane material as claimed in claim 2 or 5, characterized in that the solvent in the solution blending process in step (1) is N, N-dimethylformamide.

Technical Field

The invention relates to a high-efficiency antifouling hydrophilic ultrafiltration membrane and a preparation method thereof, in particular to a preparation method of a polymer composite material with ionic liquid uniformly distributed on the surface of the material and connected by chemical bonds.

Background

At present, the overall research and application level of the film industry and technology in China, the performance of the film product and the like have great gaps compared with the foreign advanced technology. Because the operation effect and the service life of the membrane have great relationship with the local water quality, the pollution resistance of the membrane in China is poor. Therefore, the scientific and technical research of membranes in China needs to be strengthened, a novel membrane material needs to be developed, or a high-performance membrane material modification scheme needs to be searched, so that a separation membrane with more excellent performances, including high hydrophilicity, high pollution tolerance, effective antibiosis and the like, can be obtained. Polyethersulfone (PES) has been used in ultrafiltration membrane preparation as a material for preparing separation membranes. The PES ultrafiltration membrane prepared also shows good thermal stability, strong mechanical properties and oxidation resistance, but it still has the disadvantages: strong hydrophobicity, low separation efficiency, etc. Numerous studies have demonstrated that the hydrophobicity of membranes directly affects the fouling tendency of membranes, the more hydrophobic the membranes are, the more susceptible they are to fouling. Therefore, the invention provides a high-efficiency antifouling hydrophilic polyethersulfone ultrafiltration membrane and a preparation method thereof.

First, there are two main methods for increasing the hydrophilicity of a PES porous membrane. One is to perform physical or chemical modification on the surface of the membrane: the polyethersulfone membrane is surface modified, for example by uv/ozone. However, the surface modification of the membrane by such a method may change the pore size and distribution of the membrane, resulting in the loss of other properties. Another approach is bulk modification: blending PES with hydrophilic polymers or inorganic particles is a common method to achieve physical bulk modification. This approach is primarily to use hydrophilic polymers as pore formers, such as polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG). The porous membrane blended by polyether sulfone (PES) and PVP or PEG has only temporary enhancement of hydrophilicity due to the elution effect of the PVP or PEG during the filtration process, and cannot play a permanent hydrophilic modification effect. Another common method for bulk modification is to chemically modify the PES bulk. Chemical modification is a feasible way for realizing molecular design of PES membrane material, but the chemical modification of the polyethersulfone by harsh reaction conditions and corrosive reagents is also greatly limited. It is therefore an object to provide a permanent and efficient modification process.

The invention mainly relates to a modification method for grafting ionic liquid by radiation. Reasons for selecting irradiation grafting: 1. radiation grafting techniques are well established and are used in many ways. 2. Radiation grafting can serve the purpose of permanently modifying the PES material. 3. The irradiation grafting does not need chemical reagents, and the method is simple to operate and environment-friendly. 4. Ionic Liquid (IL) is a substance which is Liquid at room temperature and is composed of ions, and the Ionic Liquid itself is a relatively hydrophilic substance, and the Ionic Liquid is grafted onto a PES molecular chain, so that the hydrophilicity of PES can be greatly improved, and the antifouling performance of PES can be improved. Meanwhile, the antibacterial performance of the ionic liquid can endow the PES porous membrane with better antibacterial performance.

The invention mainly adopts a two-step method, firstly fixes ionic liquid on a matrix polymer molecular chain through a chemical bond, and then obtains a series of porous membranes with excellent antifouling performance through immersion precipitation phase conversion. In detail, the ionic liquid connected through chemical bonds is uniformly distributed on the surfaces (inner surface and outer surface) of the polymer composite material, so that the membrane structure of the porous membrane is greatly changed, the finger-shaped holes are more communicated, the distribution density is increased, and meanwhile, the membrane holes on the upper surface and the lower surface are increased, so that the effects of good hydrophilic modification and flux improvement can be achieved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a high-efficiency antifouling and hydrophilic ultrafiltration membrane and a preparation method thereof, and the high-efficiency antifouling and hydrophilic ultrafiltration membrane is characterized in that a green solvent-ionic liquid modified PES membrane is selected, so that the problems of strong hydrophobicity, easy pollution and the like of the PES membrane are greatly improved on the premise of not changing the performance and the structure of a PES matrix, the material has good hydrophilicity and antifouling performance, the water flux is greatly improved, and the good retention rate of BSA is kept.

According to the preparation method, by a chemical modification method of Co-gamma radiation grafting, ionic liquid with chemical bond connection is uniformly distributed on the surface of a polyether sulfone material, and then an asymmetric porous membrane is prepared by an immersion precipitation phase conversion method; the mass ratio of the ionic liquid to the polyether sulfone is (2-11): 100, respectively;

the Ionic Liquid (IL) is an ionic liquid containing unsaturated bonds; preferably, the ionic liquid containing unsaturated bonds is imidazole ionic liquid; wherein the cation has the following structural formula:

wherein R1 is C1-C24 alkyl or C2-C24 alkenyl; r2 is alkenyl containing C2-C24; the anion in the ionic liquid is PF₆ ^-、BF₄ ^-、Br^-、Cl^-、I^-、NO₃ ^-、CF₃CO₂ ^-、CH₃COO^-Or (CF)₃SO₃)₂N^-；

Another object of the present invention is to provide a method for preparing the above highly effective antifouling hydrophilic polymer porous membrane.

The method comprises the following steps:

adding a polymer and an ionic liquid into a reaction kettle according to a certain ratio to carry out solution blending. The solvent is N, N-dimethylformamide. The temperature was 60 ℃.

Step (2) spreading a film on the solution after the solution blending, drying and removing the solvent to obtain a polymer and ionic liquid blended film;

step (3) placing the obtained blend film in a polyethylene plastic bag for radiation irradiation;

the irradiation is Co-gamma irradiation, and the experimental conditions are normal temperature and air or nitrogen environment;

the irradiation absorbed dose is 30 kGy;

and (4) preparing the irradiated polymer into a solution, casting a membrane by an immersion precipitation phase conversion method to obtain the multifunctional PES porous membrane, and finally performing performance characterization.

In the step (4), the polymer grafted with the ionic liquid is mainly irradiated to prepare a casting solution with a certain concentration, the casting solution is coated on a glass plate by a scraper with the thickness of 100 microns, then the glass plate is immersed in a coagulating bath, and finally the multifunctional PES porous membrane is prepared under the action of solvent exchange.

The invention has the beneficial effects that:

the PES modified membrane provided by the invention has excellent antifouling performance, and good pure water flux and BSA (bovine serum albumin) rejection rate.

According to the invention, Co-gamma irradiation with specific radiation absorption dose is adopted, so that the ionic liquid influences the membrane structure (aperture and distribution) of PES, and the retention rate of the ionic liquid to macromolecules is kept on the premise of improving flux;

the porous membrane obtained by the invention is an asymmetric membrane which is composed of a compact skin layer and a support layer, thereby not only ensuring the larger flux of the porous membrane, but also ensuring a certain selectivity, and playing a role in intercepting macromolecules.

Drawings

FIGS. 1(1) - (6) are SEM images of comparative example 1(PES porous membrane), example 1(2 wt% IL-PES modified porous membrane), example 2(4 wt% IL-PES modified porous membrane), example 3(6 wt% IL-PES modified porous membrane), example 4(10 wt% IL-PES modified porous membrane), and comparative example 2(10 wt% IL-PES-E-beam porous membrane), respectively, in which a, b, and c represent the cross-section, the micro-topography of the top surface and the bottom surface, respectively, of each sample;

FIG. 2 is a graph of contact angles for comparative example 1(PES porous membrane), example 1(2 wt% IL-PES modified porous membrane), example 2(4 wt% IL-PES modified porous membrane), example 3(6 wt% IL-PES modified porous membrane), example 4(10 wt% IL-PES modified porous membrane), and comparative example 2(10 wt% IL-PES e-beam porous membrane);

FIG. 3 is a graph of pure water flux for comparative example 1(PES porous membrane), example 1(2 wt% IL-PES modified porous membrane), example 2(4 wt% IL-PES modified porous membrane), example 3(6 wt% IL-PES modified porous membrane), example 4(10 wt% IL-PES modified porous membrane), and comparative example 2(10 wt% IL-PES e-beam porous membrane);

FIG. 4 is a graph of flux recovery and loss for comparative example 1(PES porous membrane), example 1(2 wt% IL-PES modified porous membrane), example 2(4 wt% IL-PES modified porous membrane), example 3(6 wt% IL-PES modified porous membrane), example 4(10 wt% IL-PES modified porous membrane), and comparative example 2(10 wt% IL-PES e-beam porous membrane).

Detailed Description

The present invention is described in detail below with reference to the attached drawings and the embodiments, but the present invention is not limited to the scope of the embodiments.

In this example and in the comparative examples, the polymer PES was used as matrix, produced by Basff and having the model number ULTRASON E6020P.

The imidazole-based ionic liquid containing unsaturated bonds used in the present example was: 1-vinyl-3-butylimidazolium tetrafluoroborate.