Antibacterial cellulose acetate membrane and preparation method thereof

Abstract

The invention discloses an antibacterial cellulose acetate membrane and a preparation method thereof, and belongs to the technical field of membrane materials, the prepared antibacterial cellulose acetate membrane comprises the following raw material components: cellulose acetate, succinic acid, phytic acid, a modified antibacterial substance, a solvent, a cross-linking agent and a catalyst; a preparation process of the modified antibacterial substance comprises the following steps: mixing chitosan, acetic acid and water, then adding nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide, and carrying out ultrasonic dispersion mixing and drying to obtain the modified antibacterial substance. The antibacterial cellulose acetate membrane prepared by the preparation method disclosed by the invention has good antibacterial property, high water flux and good durability, and the service life of the cellulose acetate membrane is greatly prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane materials, and particularly relates to an antibacterial cellulose acetate membrane and a preparation method thereof. Background Art

[0002] Cellulose acetate (CA) has the advantages of rich sources, good biocompatibility, low cost, easy film formation, etc., and is often used for water treatment, such as separating and desalting organisms in different water bodies.

[0003] Since cellulose acetate is a polysaccharide compound formed by connecting dehydrated glucose units, cellulose acetate is easily eroded and degraded by bacteria and other microorganisms. Furthermore, the structure of cellulose acetate is damaged, resulting in a serious decline in the water flux and durability of the cellulose acetate membrane.

[0004] Therefore, there is an urgent need to provide a new cellulose acetate membrane, which not only has good antibacterial properties, but also has high water flux and good durability, which is beneficial to improving the service life of the cellulose acetate membrane. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides an antibacterial cellulose acetate membrane and a preparation method thereof. The antibacterial cellulose acetate membrane prepared by the preparation method of the present invention has good antibacterial properties, high water flux, and good durability, greatly extending the service life of the cellulose acetate membrane.

[0006] The first aspect of the present invention provides an antibacterial cellulose acetate membrane.

[0007] An antibacterial cellulose acetate membrane, the raw material components of which include cellulose acetate, succinic acid, phytic acid, modified antibacterial agent, solvent, cross-linking agent, catalyst;

[0008] The preparation process of the modified antibacterial agent includes: mixing chitosan, acetic acid, and water, then adding nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide, and ultrasonically dispersing and mixing, followed by drying to obtain the modified antibacterial agent.

[0009] The present invention utilizes a modified antibacterial substance composed of chitosan, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide, and then through the coordination of cellulose acetate, succinic acid and phytic acid, through a double cross-linking reaction, on the one hand, the modified antibacterial substance encounters glutaraldehyde in the cross-linking agent, and a cross-linking reaction occurs, which is helpful to improve the compatibility between chitosan, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide (the composite antibacterial substance among chitosan, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide of the present invention can significantly improve the antibacterial property of the membrane to Escherichia coli and Staphylococcus aureus). On the other hand, succinic acid and phytic acid will also undergo a cross-linking reaction under the action of the cross-linking agent isocyanate and the catalyst, and further interact with cellulose acetate in the process of phase transformation into a membrane to form a three-dimensional spatial network structure with a stable structure. At the same time, it is also beneficial for the antibacterial substance to be evenly distributed in the three-dimensional spatial network structure, thereby obtaining a cellulose acetate membrane with good antibacterial property, high water flux and good durability.

[0010] Preferably, the raw material components, by weight, include 3-10 parts of cellulose acetate, 0.1-1.2 parts of succinic acid, 0.1-1.5 parts of phytic acid, 1-2.5 parts of modified antibacterial material, 15-25 parts of solvent, 0.5-3 parts of cross-linking agent, and 0.1-0.5 parts of catalyst; further preferably, the raw material components, by weight, include 4-8 parts of cellulose acetate, 0.1-1 parts of succinic acid, 0.1-1 parts of phytic acid, 1-2 parts of modified antibacterial material, 15-25 parts of solvent, 0.5-3 parts of cross-linking agent, and 0.2-0.4 parts of catalyst.

[0011] Preferably, in the preparation process of the modified antibacterial material, the weight ratio of chitosan, acetic acid, water, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide is 1:(0.1-0.5):(2-10):(0.1-1):(0.1-1); further preferably, the weight ratio of chitosan, acetic acid, water, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide is 1:(02.-0.4):(3-8):(0.2-0.8):(0.3-0.7).

[0012] Preferably, the ultrasonic dispersion time is 30-60 minutes, more preferably 40-50 minutes.

[0013] Preferably, the drying temperature is 60-100° C., and the drying time is 12-24 hours.

[0014] Preferably, during the preparation of the modified antibacterial agent, after adding water, a silane coupling agent (such as silane coupling agent KH570) is also added. The silane coupling agent undergoes hydrolysis when it encounters water. After hydrolysis, it is beneficial for the graft modification on the surfaces of inorganic substances (such as nano silver nitrate) and organic substances (such as chitosan and dodecyl dimethyl phenoxyethyl ammonium bromide), thereby obtaining a modified antibacterial agent with a more stable structure. It is also beneficial for improving the compatibility and uniformity of the modified antibacterial agent in the antibacterial cellulose acetate membrane, and further enhancing the durability of the antibacterial cellulose acetate membrane.

[0015] Preferably, by weight, the weight ratio of chitosan to the silane coupling agent is 1:(0.1 - 0.5), and more preferably 1:(0.2 - 0.4).

[0016] Preferably, the catalyst includes triethylphosphine and triethylamine.

[0017] Preferably, the solvent includes at least two of 1,4 - dioxane, methanol, ethanol, and acetone. For example, it includes 1,4 - dioxane, methanol, and acetone.

[0018] Preferably, the cross - linker includes glutaraldehyde and isocyanate.

[0019] Preferably, the isocyanate includes at least one of toluene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate.

[0020] Preferably, the cellulose acetate includes at least one of di - cellulose acetate and tri - cellulose acetate, and more preferably the cellulose acetate is composed of di - cellulose acetate and tri - cellulose acetate in a weight ratio of 1:1. A specific weight ratio can obtain an antibacterial cellulose acetate membrane with more stable performance.

[0021] The second aspect of the present invention provides a method for preparing an antibacterial cellulose acetate membrane.

[0022] A method for preparing an antibacterial cellulose acetate membrane includes the following steps:

[0023] (1) Preparation of the casting solution: Mix cellulose acetate, succinic acid, phytic acid, and a solvent, then add the modified antibacterial agent, continue to mix, filter, take the filtrate, and stand for defoaming to obtain the casting solution for standby;

[0024] (2) Phase inversion film formation: Use the casting solution prepared in step (1) and a doctor blade to scrape a film on a base cloth in a casting chamber, then allow the solvent to volatilize, then immerse it in a gel bath, and then perform heat treatment to obtain the antibacterial cellulose acetate membrane.

[0025] Preferably, the standing defoaming is carried out in an atmosphere of a protective gas. For example, it is carried out in an atmosphere of nitrogen or a noble gas. The time for standing defoaming is 1 - 12 hours.

[0026] Preferably, the conditions for volatilizing the solvent are carried out under the conditions of a temperature of 20-50 °C and a relative humidity of 20%-50%.

[0027] Preferably, the temperature corresponding to the gel bath is 5-10 °C. The gel bath is a conventional process in the art.

[0028] Preferably, the temperature of the heat treatment is 60-80 °C, and the time of the heat treatment is 20-100 minutes. The cross-linking reaction can be completed sufficiently during the heat treatment process.

[0029] The third aspect of the present invention provides an application of the antibacterial cellulose acetate membrane.

[0030] The application of the above antibacterial cellulose acetate membrane in the field of water treatment.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) The present invention uses a modified antibacterial agent composed of chitosan, nano silver nitrate, and dodecyldimethylphenoxyethyl ammonium bromide, and then through the cooperation of cellulose acetate, succinic acid, and phytic acid, through a double cross-linking reaction. On the one hand, when the modified antibacterial agent encounters glutaraldehyde in the cross-linking agent, a cross-linking reaction occurs, which helps to improve the compatibility among chitosan, nano silver nitrate, and dodecyldimethylphenoxyethyl ammonium bromide. On the other hand, succinic acid and phytic acid will also undergo a cross-linking reaction under the action of the cross-linking agent isocyanate and the catalyst. During the process of phase transformation into a membrane, they further interact with cellulose acetate to form a three-dimensional network structure with stable structure. At the same time, it is also beneficial for the antibacterial substances to be evenly distributed in the three-dimensional network structure, thereby resulting in a cellulose acetate membrane with good antibacterial properties, high water flux, and good durability.

[0033] (2) During the preparation process of the modified antibacterial agent of the present invention, after adding water, a silane coupling agent (such as silane coupling agent KH570) is also added. The silane coupling agent undergoes hydrolysis when encountering water. After hydrolysis, it is beneficial for the graft modification on the surfaces of inorganic substances (such as nano silver nitrate) and organic substances (such as chitosan and dodecyldimethylphenoxyethyl ammonium bromide), thereby obtaining a modified antibacterial agent with more stable structure. It is also beneficial to improve the compatibility and uniformity of the modified antibacterial agent in the antibacterial cellulose acetate membrane, and further improve the durability of the antibacterial cellulose acetate membrane. Detailed implementation manners

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] An antibacterial cellulose acetate film, the raw material components of which, by weight, include 6 parts of cellulose acetate (cellulose acetate is composed of diacetyl cellulose and triacetyl cellulose in a weight ratio of 1:1), 0.5 parts of succinic acid, 0.5 parts of phytic acid, 1.2 parts of modified antibacterial material, 20 parts of solvent (the solvent is composed of 1,4-dioxane, methanol and acetone in a weight ratio of 14:3:3), 0.8 parts of cross-linking agent (the cross-linking agent is composed of glutaraldehyde and toluene diisocyanate in a weight ratio of 0.5:0.3), and 0.1 parts of catalyst (the catalyst is composed of triethylphosphine and triethylamine in a weight ratio of 1:1);

[0037] The preparation process of the modified antibacterial material includes: mixing chitosan, acetic acid and water, then adding nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide, ultrasonically dispersing and mixing for 50 minutes, and drying. The drying temperature is 80°C and the drying time is 12 hours to obtain the modified antibacterial material. The weight ratio of chitosan, acetic acid, water, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide is 1:0.2:3:0.5:0.3.

[0038] A method for preparing an antibacterial cellulose acetate film comprises the following steps:

[0039] (1) Preparation of casting solution: first, cellulose acetate, succinic acid, phytic acid and solvent were mixed, then modified antimicrobial material was added, and mixing was continued (mixing temperature was 50° C., mixing time was 30 minutes), filtered, and the filtrate was taken and allowed to stand for degassing under nitrogen atmosphere for 8 hours to obtain casting solution for later use;

[0040] (2) Phase transformation into membrane: In a membrane casting chamber, the membrane casting liquid prepared in step (1) is used with a scraper to scrape a base fabric (polyester nonwoven fabric) into a membrane, and then the solvent is evaporated at a temperature of 40° C. and a relative humidity of 30%, and then the membrane is immersed in a gel bath at a temperature of 6° C., and then heat treated at a temperature of 70° C. for 60 minutes to obtain an antibacterial cellulose acetate membrane.

[0041] Example 2

[0042] An antibacterial cellulose acetate film, the raw material components of which, by weight, include 7 parts of cellulose acetate (cellulose acetate is composed of diacetyl cellulose and triacetyl cellulose in a weight ratio of 1:1), 0.8 parts of succinic acid, 0.8 parts of phytic acid, 1.5 parts of modified antibacterial material, 21 parts of solvent (the solvent is composed of 1,4-dioxane, methanol and acetone in a weight ratio of 13:4:4), 1 part of cross-linking agent (the cross-linking agent is composed of glutaraldehyde and diphenylmethane diisocyanate in a weight ratio of 0.5:0.5), and 0.2 parts of catalyst (the catalyst is composed of triethylphosphine and triethylamine in a weight ratio of 1:1);

[0043] The preparation process of the modified antibacterial material includes: mixing chitosan, acetic acid and water, then adding nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide, ultrasonically dispersing and mixing for 60 minutes, and drying. The drying temperature is 90°C and the drying time is 10 hours to obtain the modified antibacterial material. The weight ratio of chitosan, acetic acid, water, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide is 1:0.3:4:0.6:0.3.

[0044] A method for preparing an antibacterial cellulose acetate film comprises the following steps:

[0045] (1) Preparation of casting solution: first, cellulose acetate, succinic acid, phytic acid and solvent were mixed, then modified antimicrobial material was added, and mixing was continued (mixing temperature was 45° C., mixing time was 35 minutes), filtered, and the filtrate was taken and allowed to stand for degassing under nitrogen atmosphere for 8 hours to obtain casting solution for later use;

[0046] (2) Phase transformation into membrane: In a membrane casting chamber, the membrane casting liquid prepared in step (1) is used with a scraper to scrape a base fabric (polyester nonwoven fabric) into a membrane, and then the solvent is evaporated at a temperature of 50° C. and a relative humidity of 30%, and then the membrane is immersed in a gel bath at a temperature of 5° C. and then heat-treated at a temperature of 75° C. for 60 minutes to obtain an antibacterial cellulose acetate membrane.

[0047] Example 3

[0048] An antibacterial cellulose acetate film, the raw material components of which, by weight, include 6 parts of cellulose acetate (cellulose acetate is composed of diacetyl cellulose and triacetyl cellulose in a weight ratio of 1:1), 0.5 parts of succinic acid, 0.5 parts of phytic acid, 1.2 parts of modified antibacterial material, 20 parts of solvent (the solvent is composed of 1,4-dioxane, methanol and acetone in a weight ratio of 14:3:3), 0.8 parts of cross-linking agent (the cross-linking agent is composed of glutaraldehyde and toluene diisocyanate in a weight ratio of 0.5:0.3), and 0.1 parts of catalyst (the catalyst is composed of triethylphosphine and triethylamine in a weight ratio of 1:1);

[0049] The preparation process of the modified antibacterial agent includes: mixing chitosan, acetic acid, water, and silane coupling agent KH570, then adding nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide, ultrasonically dispersing for 50 minutes, drying at a temperature of 80°C for 12 hours to obtain the modified antibacterial agent. The weight ratio of chitosan, acetic acid, water, nano silver nitrate, dodecyl dimethyl phenoxyethyl ammonium bromide, and silane coupling agent KH570 is 1:0.2:3:0.5:0.3:0.4.

[0050] A method for preparing an antibacterial cellulose acetate membrane includes the following steps:

[0051] (1) Preparation of the casting solution: First, mix cellulose acetate, succinic acid, phytic acid, and a solvent, then add the modified antibacterial agent and continue mixing (at a temperature of 50°C for 30 minutes), filter, take the filtrate, and let it stand and defoam in a nitrogen atmosphere for 8 hours to obtain the casting solution for standby;

[0052] (2) Phase inversion to form a membrane: Use the casting solution prepared in step (1) and a doctor blade to scrape a film on a base fabric (polyester non-woven fabric) in a casting chamber, then let the solvent evaporate under the conditions of a temperature of 40°C and a relative humidity of 30%, then immerse it in a gel bath with a corresponding temperature of 6°C, and then perform heat treatment at a temperature of 70°C for 60 minutes to obtain the antibacterial cellulose acetate membrane.

[0053] Comparative Example 1

[0054] Compared with Example 1, the difference in Comparative Example 1 is only that an equal amount of maleic anhydride is used instead of succinic acid and phytic acid, and other components and processes are the same as in Example 1.

[0055] Comparative Example 2

[0056] Compared with Example 1, the difference in Comparative Example 2 is only that an equal amount of succinic acid is used instead of phytic acid, and other components and processes are the same as in Example 1.

[0057] Comparative Example 3

[0058] Compared with Example 1, the difference in Comparative Example 3 is only that an equal amount of dodecyl dimethyl phenoxyethyl ammonium bromide is used instead of nano silver nitrate, and other components and processes are the same as in Example 1.

[0059] Product effect test

[0060] Take the antibacterial cellulose acetate membranes prepared in the above Examples 1-3 and Comparative Examples 1-3. Immerse the antibacterial cellulose acetate membranes in tap water. Under the conditions of an operating pressure of 0.69 MPa and a temperature of 25 °C, measure the water fluxes at the 1st hour, the 1st month, and the 6th month of immersion. After the antibacterial cellulose acetate membranes are immersed for the corresponding time, take out the antibacterial cellulose acetate membranes and refer to the standard of GB / T 31402-2015 to test the antibacterial effects against Escherichia coli and Staphylococcus aureus. The results are shown in Table 1.

[0061] Table 1

[0062]

[0063] As can be seen from Table 1, compared with the comparative examples, the membranes prepared in the examples of the present invention have higher water fluxes, good antibacterial properties, and good durability.

[0064] As can be seen from Example 1 and Example 3, the addition of the silane coupling agent KH570 significantly improves the durability of the antibacterial cellulose acetate membrane. Even after being immersed for 6 months, the water flux and antibacterial properties still remain good.

[0065] As can be seen from Example 1 and Comparative Examples 1-3, when changing the succinic acid and phytic acid in the raw materials, or the types of antibacterial substances, the water flux and antibacterial properties of the antibacterial cellulose acetate membrane both decrease significantly with the passage of time. Especially when the type of antibacterial substance was changed in Comparative Example 3, by the 6th month, the antibacterial cellulose acetate membrane rotted severely. The preparation process of the modified antibacterial substance of the present invention has a significant impact on the durability of the antibacterial cellulose acetate membrane.

[0066] It should be noted that in this article, terms such as "including" or "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or device.

[0067] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An antibacterial cellulose acetate membrane, characterized in that, Its raw material components include cellulose acetate, succinic acid, phytic acid, modified antibacterial substances, solvents, cross-linking agents, and catalysts; The preparation process of the modified antibacterial substance comprises: mixing chitosan, acetic acid and water, then adding nano silver nitrate and dodecyl dimethylphenoxyethyl ammonium bromide, ultrasonically dispersing and mixing, and drying to obtain the modified antibacterial substance.

2. The antibacterial cellulose acetate membrane according to claim 1, characterized in that, The raw material components, by weight, include 3-10 parts of cellulose acetate, 0.1-1.2 parts of succinic acid, 0.1-1.5 parts of phytic acid, 1-2.5 parts of modified antibacterial material, 15-25 parts of solvent, 0.5-3 parts of cross-linking agent, and 0.1-0.5 parts of catalyst.

3. The antibacterial cellulose acetate membrane according to claim 1, characterized in that, In the preparation process of the modified antibacterial material, the weight ratio of chitosan, acetic acid, water, nano silver nitrate and dodecyl dimethyl phenoxyethyl ammonium bromide is 1:(0.1-0.5):(2-10):(0.1-1):(0.1-1).

4. The antibacterial cellulose acetate membrane according to claim 1, wherein, The catalyst includes triethylphosphine and triethylamine.

5. The antibacterial cellulose acetate membrane according to claim 1, characterized in that, The solvent includes at least two of 1,4-dioxane, methanol, ethanol and acetone.

6. The antibacterial cellulose acetate membrane according to claim 1, wherein The cross-linking agent includes glutaraldehyde and isocyanate.

7. The antibacterial cellulose acetate membrane according to any one of claims 1-6, wherein, The cellulose acetate includes at least one of diacetyl cellulose and triacetyl cellulose.

8. The preparation method of the antibacterial cellulose acetate membrane according to any one of claims 1-7, characterized in that, The following steps are involved: (1) Preparation of casting solution: cellulose acetate, succinic acid, phytic acid and solvent are mixed, and then modified antibacterial material is added, and the mixture is continuously mixed, filtered, and the filtrate is collected and allowed to stand for degassing to obtain casting solution for later use; (2) Phase transformation into membrane: In a membrane casting chamber, the membrane casting liquid prepared in step (1) is used with a scraper to scrape a membrane on a base cloth, and then the solvent is evaporated, and then the membrane is immersed in a gel bath, and then heat-treated to obtain the antibacterial cellulose acetate membrane.

9. The preparation method according to claim 8, wherein, The conditions for volatilizing the solvent are a temperature of 20-50° C. and a relative humidity of 20%-50%; and / or, the temperature of the heat treatment is 60-80° C. and the time of the heat treatment is 20-100 minutes.

10. Use of the antibacterial cellulose acetate membrane according to any one of claims 1 to 7 in the field of water treatment.

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