An amphiphilic graft polymer hydrophilically modified polymer ultrafiltration membrane and a preparation method thereof

Abstract

The application belongs to the technical field of filter membrane preparation, and particularly relates to a kind of amphiphilic grafting polymer hydrophilic modified polymer ultrafiltration membrane and its preparation method. Carboxymethyl chitosan is grafted with aminated polyether sulfone, wrapped on MWCNT with non-covalent bond, to prepare amphiphilic grafting polymer. The hydrophilicity, permeability and antifouling performance of MWCNT / PES-g-carboxymethyl chitosan blended membrane are evaluated, and the results show that the modified membrane has good antifouling performance and high permeability, and has practical application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of filter membrane preparation, and particularly relates to a kind of amphiphilic graft polymer hydrophilic modified polymer ultrafiltration membrane and its preparation method. BACKGROUND

[0002] Among numerous membrane separation technologies, ultrafiltration (UF) is considered as an effective water treatment method due to its ability to remove colloids and macromolecules. However, the strong hydrophobicity of the membrane polymer substrate limits the membrane's permeability and leads to membrane fouling, thereby significantly reducing the membrane's reusability. Therefore, to meet the requirements of membrane antifouling and permeability, new strategies for modifying the membrane are urgently needed. Various methods have been used to modify the membrane, including surface coating, blending with hydrophilic polymers, plasma treatment, or UV-induced grafting of hydrophilic functional groups. Although these methods have produced certain modification effects, there are many limitations in the use of these technologies, including poor solubility of hydrophilic modification materials in organic casting solutions, and inevitable elution of long-term use of modification materials due to poor compatibility with polymer membranes, strict reaction conditions. SUMMARY

[0003] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a method for preparing a two-graft polymer hydrophilic modified polymer ultrafiltration membrane.

[0004] Another purpose of the present application is to provide a two-graft polymer hydrophilic modified polymer ultrafiltration membrane prepared by the above method.

[0005] The purpose of the present application is achieved by the following scheme:

[0006] A method for preparing a two-graft polymer hydrophilic modified polymer ultrafiltration membrane, comprising the following steps:

[0007] Mixing and stirring carboxymethyl chitosan with multi-walled carbon nanotubes (MWCNT) to obtain MWCNT / carboxymethyl chitosan;

[0008] Adding PES-NH2 and MWCNT / carboxymethyl chitosan in N,N-dimethylacetamide (DMAc) and performing amidation reaction under heating conditions to obtain MWCNT / PES-g-carboxymethyl chitosan;

[0009] Dissolving polyethersulfone, MWCNT / PES-g-carboxymethyl chitosan and polyvinylpyrrolidone in DMAc, then pouring on a substrate and soaking in water to obtain a two-graft polymer hydrophilic modified polymer ultrafiltration membrane.

[0010] Preferably, the mass ratio of carboxymethyl chitosan to multi-walled carbon nanotubes is 1-5:1, preferably 2-4:1.

[0011] Preferably, the carboxymethyl chitosan and the multi-walled carbon nanotube are stirred at 50-70℃, and the stirring time is preferably 4-10h.

[0012] Preferably, the carboxymethyl chitosan and the multi-walled carbon nanotube are mixed in water, and the mass-volume ratio of the carboxymethyl chitosan to water is 0.5-3g:50ml.

[0013] Preferably, the mass ratio of the PES-NH2 and the MWCNT / carboxymethyl chitosan is 0.5-3:0.5-3, and more preferably 1:1-3.

[0014] Preferably, the mass-volume ratio of the PES-NH2 to DMAc is 1g:5-15ml, and preferably 1g:8-12ml.

[0015] Preferably, the reaction temperature of the amidation reaction is 50-70℃, and the reaction time is 1-5h.

[0016] Preferably, the mass ratio of the polyether sulfone, the polyvinylpyrrolidone and the MWCNT / PES-g-carboxymethyl chitosan is 18:2:0.2-1.5, and more preferably 18:2:0.45-0.85.

[0017] Preferably, the mass ratio of the MWCNT / PES-g-carboxymethyl chitosan to DMAc is 0.2-1.5:100.

[0018] Preferably, the PES-NH2 is prepared by the following method:

[0019] (1) mixing and stirring a mixed solution of HNO3 and H2SO4 with polyether sulfone to obtain PES-NO2;

[0020] (2) dissolving the PES-NO2 in DMSO, adding a reducing agent Na2S2O4, and obtaining amino polyether sulfone (PES-NH2) after reaction.

[0021] In step (2), the mass ratio of PES-NO2 to Na2S2O4 is 3-6:45-60;

[0022] In step (2), the mass-volume ratio of PES-NO2 to DMSO is 1g:5-15ml;

[0023] In step (2), the reaction temperature is 70-90℃, and the reaction time is 3-8h.

[0024] An amphiphilic grafted polymer hydrophilic modified polymer ultrafiltration membrane is prepared by the above method.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] The application provides a kind of amphiphilic graft polymer (MWCNT / PES-g-carboxymethyl chitosan), the method for preparing antifouling high permeable membrane.Caroxy methyl chitosan (carboxymethyl chitosan) is grafted with amino polyether sulfone (PES-NH2), and is wrapped on MWCNT with non-covalent bond to prepare amphiphilic graft polymer.The hydrophilicity, permeability and antifouling performance of MWCNT / PES-g-carboxymethyl chitosan blend membrane are evaluated, and the results show that the modified membrane has good antifouling performance and high permeability, and has practical application potential. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the cross-section electron micrograph of MWCNT / PES-g-carboxymethyl chitosan modified membrane (a x 1000, b x 5000, c x 8000)

[0028] Figure 2 It is the time variation flux of the modified membrane obtained by adding different mass fractions of amphiphilic polymer. DETAILED DESCRIPTION

[0029] The application will be further described in detail below in combination with examples, but the embodiments of the application are not limited thereto.

[0030] The reagents used in the examples can be commonly purchased from the market unless otherwise specified.

[0031] Example 1

[0032] An amphiphilic graft polymer hydrophilic modified polymer ultrafiltration membrane and a preparation method thereof, comprising the following steps:

[0033] (1) HNO3 (160 ml) and H2SO4 (40 ml) are mixed in a 500 ml round-bottom flask. After the mixed solution is cooled, the polyether sulfone raw material is slowly added, stirred at 25℃ for 2h, and the product is washed with deionized water for multiple times to obtain product a (PES-NO2).

[0034] (2) 3g of PES-NO2 is dried in a 50℃ vacuum box for 24h, then dissolved in DMSO (60ml), and a reducing agent Na2S2O4 (52g) is added, stirred at 80℃ for 5h, and finally the mixture is precipitated in deionized water and dried in a 50℃ vacuum box for 24h to obtain product b (PES-NH2).

[0035] (3) 3g of carboxymethyl chitosan (carboxymethyl chitosan) and 1g of multi-walled carbon nanotubes (MWCNT) are added to 150ml of water, stirred at 60℃ for 6h, and then carboxymethyl chitosan wrapped MWCNT is obtained as product c (MWCNT / carboxymethyl chitosan).

[0036] (4) 1 g of product b and 1 g of product c were added in 10 ml of DMAc, and amidation reaction was carried out under heating condition, after reaction for 3 h, the synthesized product MWCNT / PES-g-carboxymethyl chitosan was washed and leached by deionized water, and product d was obtained.

[0037] (5) Polyether sulfone (PES), product d and polyvinylpyrrolidone (PVP) were used as raw materials, and casting solution was obtained by dissolving in N, N-dimethylacetamide (DMAc) for 8 h (PES 18 wt%, PVP 2 wt%, product d 0.25 wt%, 0.5 wt%, 0.75 wt% and 1.0 wt% respectively). After degassing the casting solution at 80℃ for 6 h, the casting solution was poured on a glass plate by using a doctor blade, and then immersed in deionized water to obtain a hydrophilic polyether sulfone ultrafiltration membrane.

[0038] Table 1 Pure water flux and contact angle of MWCNT / PES-g-carboxymethyl chitosan modified membrane with different mass fractions

[0039]

[0040] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application shall be equivalent replacement methods and shall be included in the protection scope of the present application.

Claims

1. A method for preparing a hydrophilic modified polymer ultrafiltration membrane grafted with amphiphilic polymers, characterized in that... Includes the following steps: Carboxymethyl chitosan was mixed and stirred with multi-walled carbon nanotubes to obtain MWCNT / carboxymethyl chitosan; PES-NH2 and MWCNT / carboxymethyl chitosan were added to N,N-dimethylacetamide and amidation reaction was carried out under heating conditions to obtain multi-walled carbon nanotubes MWCNT / PES-g-carboxymethyl chitosan. Polyethersulfone, MWCNT / PES-g-carboxymethyl chitosan and polyvinylpyrrolidone were dissolved in N,N-dimethylacetamide, then cast onto a substrate and immersed in water to obtain an amphiphilic grafted polymer hydrophilic modified polymer ultrafiltration membrane.

2. The method according to claim 1, characterized in that: The mass ratio of carboxymethyl chitosan to multi-walled carbon nanotubes is 1 to 5:

1.

3. The method according to claim 1, characterized in that: The carboxymethyl chitosan and multi-walled carbon nanotubes were stirred at 50–70°C for 4–10 hours.

4. The method according to claim 1, characterized in that: The mass ratio of PES-NH2 to MWCNT / carboxymethyl chitosan is 0.5–3:0.5–3; the mass-to-volume ratio of PES-NH2 to N,N-dimethylacetamide is 1 g:5–15 ml.

5. The method according to claim 1, characterized in that: The amidation reaction is carried out at a temperature of 50–70°C for 1–5 hours.

6. The method according to claim 1, characterized in that: The mass ratio of polyethersulfone, polyvinylpyrrolidone, and MWCNT / PES-g-carboxymethyl chitosan is 18:2:0.2-1.

5.

7. The method according to claim 1, characterized in that: The mass ratio of MWCNT / PES-g-carboxymethyl chitosan to DMAc is 0.2–1.5:

100.

8. The method according to claim 1, characterized in that... The PES-NH2 was prepared by the following method: (1) Mix the mixed solution of HNO3 and H2SO4 with polyethersulfone and stir to obtain PES-NO2; (2) PES-NO2 is dissolved in DMSO, and reducing agent Na2S2O4 is added. After the reaction, amino-modified polyether sulfone is obtained.

9. The method according to claim 8, characterized in that: In step (2), the mass ratio of PES-NO2 to Na2S2O4 is 3-6:45-60; In step (2), the mass-to-volume ratio of PES-NO2 to DMSO is 1g: 5-15ml; In step (2), the reaction temperature is 70-90℃ and the reaction time is 3-8h.

10. A hydrophilic modified polymer ultrafiltration membrane grafted with an amphiphilic polymer, prepared by the method described in any one of claims 1 to 9.

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