Modified modified ceramic membrane and preparation process thereof

Abstract

The application discloses a modified modified ceramic membrane and a preparation process thereof, and belongs to the technical field of material science. The modified modified ceramic membrane comprises a ceramic base prepared by adopting Al2O3 as a base material through a sol-gel method, wherein ZnO nanowires are embedded in the ceramic base, and a SiO2 nano modification structure is deposited on the surface of the ceramic base; and a biological derivative material antibacterial layer is further covered on the surface of the formed SiO2 nano modification structure. The application solves the problem of insufficient stability of the existing ceramic membrane. The application provides the modified modified ceramic membrane and the preparation process thereof, adopts Al2O3 as the base material, embeds the ZnO nanowires in the base material, improves the mechanical strength and separation efficiency of the ceramic membrane, and combines the SiO2 nano modification structure with polyvinyl alcohol and chitosan; the SiO2 nanowires can improve the rigidity of the composite material, and the flexibility of the chitosan can improve the overall toughness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material science, in particular to a modified ceramic membrane and a preparation process thereof. BACKGROUND

[0002] With the development of industrial technology, there is an increasing demand for efficient and stable separation membranes. Ceramic membranes show great application potential in gas separation, water treatment and other fields due to their unique physical and chemical properties. However, the stability of traditional ceramic membranes in some special environments is insufficient, which limits their application range.

[0003] A modification method of ceramic membranes and modified ceramic membranes are disclosed in Chinese Patent No. CN106669440B. A silane compound is coated on the surface of the ceramic membrane by impregnation or deposition method. The coated ceramic membrane is heat treated in a protective atmosphere, and the modified ceramic membrane is obtained after natural cooling. The modified ceramic membrane prepared by modification has the characteristics of high long-term stability, strong acid and alkali resistance, and super-hydrophobicity compared with common organic modification materials. However, the patent is not suitable for ceramic membranes that require hydrophilic properties, and ceramic membranes with hydrophilic properties often also require strong antibacterial properties. SUMMARY

[0004] The present application aims to provide a modified ceramic membrane and a preparation process thereof. Al2O3 is used as the base material, and ZnO nanowires are embedded in the base material to improve the mechanical strength and separation efficiency of the ceramic membrane. SiO2 nano-modification structure is deposited on the surface of the ceramic membrane. The SiO2 nano-modification structure is combined with polyvinyl alcohol and chitosan. SiO2 nanowires can improve the rigidity of the composite material, solving the problems raised in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a modified ceramic membrane, comprising a ceramic substrate prepared by sol-gel method using Al2O3 as the base material, ZnO nanowires embedded in the ceramic substrate, and SiO2 nano-modification structure deposited on the surface of the ceramic substrate, wherein the surface of the formed SiO2 nano-modification structure is further covered with a biologically derived material antibacterial layer, and the biologically derived material antibacterial layer at least comprises a chitosan coating layer.

[0006] Preferably, the preparation method of the ZnO nanowires is as follows: a ZnO seed layer is deposited on the substrate as a nucleation point, the substrate is placed in a reactor, vacuum is applied, heated to the reaction temperature, zinc source Zn and oxygen are introduced, and the reaction is carried out at 300-500℃. After the reaction is completed, the reactor is naturally cooled to room temperature, the sample is taken out from the reactor, washed and dried to obtain ZnO nanowires.

[0007] Preferably, the SiO2 nano-modified structure is a network structure formed on the surface of the ceramic substrate by chemical vapor deposition.

[0008] Preferably, the antibacterial layer of the biologically derived material is an alternating composite layer of polyvinyl alcohol and chitosan.

[0009] Another technical problem to be solved by the present application is to provide a preparation process for modifying and modifying ceramic membranes, comprising the following steps:

[0010] Step one: dissolve aluminum alkoxide in an organic solvent, add water and a catalyst, stir to form a uniform sol, and uniformly disperse ZnO nanowires into the sol;

[0011] Step two: coat the above sol on the support and dry;

[0012] Step three: sinter the dried coating at a certain temperature to form a ceramic membrane;

[0013] Step four: deposit SiO2 nano-modified structure on the surface of the ceramic membrane by chemical vapor deposition technology;

[0014] Step five: prepare a biologically derived material impregnating solution and coat a biologically derived material antibacterial layer on the surface of the ceramic membrane by deposition method;

[0015] Step six: clean and dry the modified ceramic membrane.

[0016] Preferably, the catalyst in step one is one of nitric acid, hydrochloric acid, ammonia and potassium hydroxide, and the content of ZnO nanowires is 0.5wt%-1wt%.

[0017] Preferably, the sintering temperature in step three is 900-1000℃, and the holding time is 2-3 hours.

[0018] Preferably, the specific method of step four is as follows:

[0019] The ceramic membrane is pretreated as necessary, such as ultrasonic cleaning, pickling, etc., to remove surface contaminants and oxide layers, and the treated ceramic membrane is placed in a CVD reactor, SiH2Cl2, oxygen and carrier gas N2 are introduced into the reactor, the temperature in the reactor is adjusted to 900-1200℃, and the reaction is carried out in an inert atmosphere, the deposition reaction is carried out at a certain temperature and pressure, and the SiO2 nano-network structure is formed on the surface of the ceramic membrane. After deposition, slowly cool the reactor to room temperature to avoid cracks in the membrane layer caused by sudden temperature changes.

[0020] Preferably, the biological material impregnation solution comprises a polyvinyl alcohol solution and a chitosan solution, the polyvinyl alcohol solution is prepared by adding a desired amount of polyvinyl alcohol powder into deionized water, heating the mixture to 80-90 DEG C and continuously stirring until the polyvinyl alcohol is completely dissolved, and cooling to room temperature to obtain a polyvinyl alcohol solution with a concentration of 1wt%-5wt%; the chitosan solution is prepared by dissolving chitosan in an acetic acid solution to obtain a chitosan solution with a concentration of 0.5wt%-2wt%.

[0021] Preferably, the specific steps of the deposition method in step five are as follows: the pretreated ceramic membrane is immersed in the polyvinyl alcohol solution for 1-5 minutes, the ceramic membrane is taken out and washed with deionized water to remove excess polyvinyl alcohol, the ceramic membrane is again immersed in the chitosan solution for the same time, the ceramic membrane is taken out and washed with deionized water, and the above-mentioned deposition steps of polyvinyl alcohol and chitosan are repeated several times to form a multilayer composite membrane, and finally the membrane is dried at room temperature.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The modified ceramic membrane and the preparation process thereof provided by the present application use Al2O3 as a base material and embed ZnO nanowires in the base material to improve the mechanical strength and separation efficiency of the ceramic membrane, and at the same time, a SiO2 nano modification structure is deposited on the surface of the ceramic membrane, the SiO2 nano modification structure is combined with polyvinyl alcohol and chitosan, the SiO2 nanowires can improve the rigidity of the composite material, and the flexibility of chitosan can improve the toughness of the whole, the combination of the two can improve the comprehensive mechanical properties of the material, chitosan itself has antibacterial properties, and the presence of SiO2 nanowires can improve the uniformity of the distribution of the antibacterial components and enhance the antibacterial effect. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The modified ceramic membrane processing flow chart of the present application is as follows: DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Embodiment one:

[0027] In order to solve the problem of insufficient stability of the existing traditional ceramic membrane in some special environments, which limits its application range, please refer to Figure 1The embodiment provides the following technical scheme:

[0028] In the embodiment, the modified modified ceramic membrane comprises a ceramic substrate prepared by adopting Al2O3 as a base material through a sol-gel method, wherein ZnO nanowires are embedded in the ceramic substrate, and a SiO2 nano modification structure is deposited on the surface of the ceramic substrate; the SiO2 nano modification structure is a network structure formed on the surface of the ceramic substrate by a chemical vapor deposition method; the ZnO nanowires and the SiO2 nano modification structure are used for constructing a nano structure, improving the mechanical strength and separation efficiency of the ceramic membrane; the surface of the SiO2 nano modification structure further covers an antibacterial layer of a biological derivative material; the antibacterial layer of the biological derivative material is a composite layer in which polyvinyl alcohol and chitosan are alternately arranged; the chitosan can be adsorbed on the SiO2 nano modification structure through hydrogen bond interaction to form a stable composite material; the chitosan can be filled in the gaps between the SiO2 nano modification structures to enhance the overall structural stability of the composite material; the polyvinyl alcohol solution and the chitosan solution are alternately coated to form a multilayer structure, so as to improve the hydrophilicity and antibacterial performance of the membrane; the SiO2 nanowires can improve the rigidity of the composite material, and the flexibility of the chitosan can improve the toughness of the whole; the combination of the two can improve the comprehensive mechanical properties of the material; the chitosan itself has antibacterial performance, and the presence of the SiO2 nanowires can improve the uniformity of the distribution of the antibacterial components and enhance the antibacterial effect; the hydrophilicity of the chitosan can improve the wettability of the composite material, and the SiO2 nanowires can increase the roughness of the surface of the material, thereby improving the hydrophilicity of the composite material; a layer of intermediate material of polyvinyl alcohol solution is introduced between the chitosan and the SiO2 nanowires to promote the combination of the two.

[0029] In order to better show the preparation process of the modified modified ceramic membrane, the embodiment provides a preparation process of the modified modified ceramic membrane, which comprises the following steps:

[0030] Step one: aluminum alkoxide, water and ethanol are mixed in a ratio of 1:2:6, nitric acid is added as a catalyst, and stirring is performed to form a uniform sol; the ZnO nanowires are uniformly dispersed in the sol;

[0031] The preparation method of the ZnO nanowires is as follows: a ZnO seed layer is deposited on a substrate as a nucleation point; the substrate is placed in a reactor, vacuum is drawn, heating is performed to a reaction temperature, zinc source Zn and oxygen are introduced, reaction is performed at 350 DEG C, after the reaction is completed, the reactor is naturally cooled to room temperature, the sample is taken out from the reactor, and cleaning and drying are performed to obtain the ZnO nanowires; the content of the ZnO nanowires is 0.5wt%;

[0032] Step two: the sol is coated on a support, and drying treatment is performed;

[0033] Step three: sinter the dried coating at a certain temperature to form a ceramic film, the sintering temperature is 900℃, and the holding time is 2 hours;

[0034] Step four: ultrasonic cleaning of the ceramic film to remove surface contaminants and oxide layers, and the treated ceramic film is placed in a CVD reactor, SiH2Cl2, oxygen and carrier gas N2 are introduced into the reactor, the temperature in the reactor is adjusted to 900℃, and the reaction is carried out in an inert atmosphere, the pressure in the reaction chamber is 100Pa, and the radio frequency power is 70W, so that the SiO2 nanometer network structure is formed on the surface of the ceramic film, after deposition, slowly cool the reactor to room temperature to avoid temperature sudden change leading to film layer crack;

[0035] Step five: configure a bio-derived material impregnation solution, and coat a bio-derived material antibacterial layer on the surface of the ceramic film by deposition method, the bio-derived material impregnation solution includes polyvinyl alcohol solution and chitosan solution, the preparation method of polyvinyl alcohol solution is as follows: add the required weight of polyvinyl alcohol powder into deionized water, heat the mixture to 80℃, and continue to stir until the polyvinyl alcohol is completely dissolved, cool to room temperature to obtain a polyvinyl alcohol solution with a concentration of 2wt%; the preparation method of chitosan solution is as follows: dissolve chitosan in acetic acid solution to obtain a chitosan solution with a concentration of 1wt%;

[0036] The pretreated ceramic film is immersed in the polyvinyl alcohol solution for 3 minutes, the ceramic film is taken out and washed with deionized water to remove excess polyvinyl alcohol, the ceramic film is immersed in the chitosan solution again for the same time, the ceramic film is taken out and washed with deionized water, the above-mentioned polyvinyl alcohol and chitosan deposition steps are repeated three times to form a multilayer composite film, and finally the film is dried at room temperature;

[0037] Step six: clean and dry the modified ceramic film.

[0038] Example two:

[0039] The aluminum alkoxide, water and ethanol are mixed in a ratio of 1:2:6, nitric acid is added as a catalyst, and stirring is performed to form a uniform sol, the ZnO nanowires are uniformly dispersed in the sol, the content of the ZnO nanowires is 1wt%, the sol is coated on a support, drying treatment is performed, the dried coating is sintered at a certain temperature to form a ceramic membrane, the sintering temperature is 1000°C, and the ceramic membrane is kept at the temperature for 3 hours, the ceramic membrane is subjected to ultrasonic cleaning to remove surface contaminants and an oxide layer, the treated ceramic membrane is placed in a CVD reactor, dichlorodihydrogen silicon SiH2Cl2, oxygen and carrier gas nitrogen N2 are introduced into the reactor, the temperature in the reactor is adjusted to 900°C, the pressure in the reaction chamber is 100 Pa, and the radio frequency power is 70 W, so that the SiO2 nanometer network structure is formed on the surface of the ceramic membrane, after deposition is completed, the reactor is slowly cooled to room temperature; the pretreated ceramic membrane is immersed in a 2wt% polyvinyl alcohol solution for 3 minutes, the ceramic membrane is taken out and washed with deionized water to remove excess polyvinyl alcohol, the ceramic membrane is again immersed in a 1wt% chitosan solution for the same time, the ceramic membrane is taken out and washed with deionized water, and the above-mentioned polyvinyl alcohol and chitosan deposition steps are repeated three times to form a multilayer composite membrane, and finally the membrane is dried at room temperature; the modified ceramic membrane is cleaned and dried.

[0040] Example Three

[0041] The aluminum alkoxide, water and ethanol are mixed in a ratio of 1:2:6, nitric acid is added as a catalyst, and stirring is performed to form a uniform sol, the ZnO nanowires are uniformly dispersed in the sol, the content of the ZnO nanowires is 1wt%, the sol is coated on a support, drying treatment is performed, the dried coating is sintered at a certain temperature to form a ceramic membrane, the sintering temperature is 1000°C, and the ceramic membrane is kept at the temperature for 3 hours, the ceramic membrane is subjected to ultrasonic cleaning to remove surface contaminants and an oxide layer, the treated ceramic membrane is placed in a CVD reactor, dichlorodihydrogen silicon SiH2Cl2, oxygen and carrier gas nitrogen N2 are introduced into the reactor, the temperature in the reactor is adjusted to 900°C, the pressure in the reaction chamber is 100 Pa, and the radio frequency power is 70 W, so that the SiO2 nanometer network structure is formed on the surface of the ceramic membrane, after deposition is completed, the reactor is slowly cooled to room temperature; the pretreated ceramic membrane is immersed in a 2wt% polyvinyl alcohol solution for 3 minutes, the ceramic membrane is taken out and washed with deionized water to remove excess polyvinyl alcohol, the ceramic membrane is again immersed in a 1wt% chitosan solution for the same time, the ceramic membrane is taken out and washed with deionized water, and the above-mentioned polyvinyl alcohol and chitosan deposition steps are repeated three times to form a multilayer composite membrane, and finally the membrane is dried at room temperature; the modified ceramic membrane is cleaned and dried.

[0042] The ceramic membrane prepared in the above-mentioned examples is detected to obtain the following data:

[0043] Example One Example Two Example Three Contact angle 20° 20° 16° Compressive strength 500 MPa 600 MPa 550 MPa Antibacterial rate 99％ 99％ 99％ Maximum working temperature 950℃ 980℃ 1020℃

[0044] From the above table, it can be concluded that the ceramic membrane processed in the embodiment of the present application has good hydrophilicity, high mechanical strength, good antibacterial property, and can work in a high-temperature environment above 900 DEG C, and has good heat resistance.

[0045] In summary: the modified ceramic membrane and the preparation process thereof proposed in the present application use Al2O3 as the base material, and embed ZnO nanowires in the base material to improve the mechanical strength and separation efficiency of the ceramic membrane, and deposit SiO2 nano modification structure on the surface of the ceramic membrane, the SiO2 nano modification structure is combined with chitosan through polyvinyl alcohol, the SiO2 nanowires can improve the rigidity of the composite material, and the flexibility of chitosan can improve the toughness of the whole, the combination of the two can improve the comprehensive mechanical properties of the material, chitosan itself has antibacterial property, and the existence of the SiO2 nanowires can improve the uniformity of the distribution of the antibacterial components and enhance the antibacterial effect.

[0046] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0047] Although the embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, alternatives, and variations can be made thereto without departing from the principles and spirit of the present application.

Claims

1. A modified ceramic membrane, comprising a ceramic matrix prepared by sol-gel method using Al2O3 as the matrix material, wherein ZnO nanowires are embedded in the ceramic matrix, and SiO2 nano-modified structures are deposited on the surface of the ceramic matrix, and the surface of the formed SiO2 nano-modified structures is further covered with a bio-derived antibacterial layer, wherein the bio-derived antibacterial layer includes at least a chitosan coating layer; The ZnO nanowires are prepared as follows: a ZnO seed layer is deposited on a substrate as nucleation sites. The substrate is placed in a reactor, then a vacuum is drawn, and the temperature is heated to the reaction temperature. Zinc source Zn and oxygen are introduced, and the reaction is carried out at 300-500℃. After the reaction is completed, the reactor is allowed to cool naturally to room temperature. The sample is taken out from the reactor, cleaned and dried to obtain ZnO nanowires. The SiO2 nano-modified structure is a network structure formed on the surface of a ceramic substrate by chemical vapor deposition. The antibacterial layer of the bio-derived material is a composite layer of alternating polyvinyl alcohol and chitosan; The preparation process of the modified ceramic film is characterized by comprising the following steps: Step 1: Dissolve aluminum alkoxide in an organic solvent, add water and catalyst, stir to form a homogeneous sol, and uniformly disperse ZnO nanowires into the sol; Step 2: Apply the above sol to the support and allow it to dry. Step 3: Sinter the dried coating at a certain temperature to form a ceramic film; Step 4: Deposit SiO2 nanostructures on the ceramic film surface using chemical vapor deposition (CVD). Step 5: Prepare the bio-derived material impregnation solution and coat the ceramic membrane surface with a bio-derived material antibacterial layer by deposition. Step 6: Clean and dry the modified ceramic membrane.

2. The modified ceramic membrane according to claim 1, characterized in that: The catalyst in step one is one of nitric acid, hydrochloric acid, ammonia, and potassium hydroxide, and the ZnO nanowire content is 0.5 wt%-1 wt%.

3. The modified ceramic membrane according to claim 2, characterized in that: In step three, the sintering temperature is 900℃-1000℃, and the temperature is maintained for 2-3 hours.

4. The modified ceramic membrane according to claim 3, characterized in that: The specific method for step four is as follows: The ceramic membrane undergoes necessary pretreatment to remove surface contaminants and oxide layers. The pretreated ceramic membrane is then placed in a CVD reactor, and silicon dichlorosilane (SiH2Cl2), oxygen, and nitrogen (N2) are introduced into the reactor. The temperature inside the reactor is adjusted to 900-1200℃, and the reaction is carried out in an inert atmosphere. The deposition reaction is carried out under the set temperature and pressure to form a SiO2 nanostructure on the surface of the ceramic membrane. After deposition, the reactor is slowly cooled to room temperature to avoid sudden temperature changes that could cause cracks in the membrane.

5. The modified ceramic membrane according to claim 4, characterized in that: The impregnation solution for the bio-derived material includes a polyvinyl alcohol solution and a chitosan solution. The polyvinyl alcohol solution is prepared as follows: the required weight of polyvinyl alcohol powder is added to deionized water, the mixture is heated to 80-90°C, and stirred continuously until the polyvinyl alcohol is completely dissolved. After cooling to room temperature, a polyvinyl alcohol solution with a concentration of 1 wt%-5 wt% is obtained. The chitosan solution is prepared as follows: chitosan is dissolved in acetic acid solution to obtain a chitosan solution with a concentration of 0.5 wt%-2 wt%.

6. The modified ceramic membrane according to claim 5, characterized in that: The specific steps of the deposition method in step five are as follows: Immerse the pretreated ceramic membrane in a polyvinyl alcohol solution for 1-5 minutes, remove the ceramic membrane, rinse it with deionized water to remove excess polyvinyl alcohol, immerse the ceramic membrane in a chitosan solution again for the same time, remove the ceramic membrane, rinse it with deionized water, repeat the above polyvinyl alcohol and chitosan deposition steps several times to form a multilayer composite membrane, and finally dry the membrane at room temperature.

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