A super-hydrophobic ceramic membrane based on zinc oxide nanoflower balls and a preparation method thereof

Abstract

This invention belongs to the field of superhydrophobic technology and discloses a superhydrophobic ceramic membrane based on zinc oxide nanoflowers and its preparation method. Addressing the problems of poor coating stability, complex and time-consuming processes, and difficulty in large-scale production in existing processes, this invention first prepares zinc oxide nanoflower powder with regular morphology by a solvent mixture of deionized water and ethylene glycol, supplemented with zinc acetate and urea, through a solvothermal reaction, washing, drying, and calcination annealing. Then, a silica colloidal solution and a zinc oxide dispersion are prepared separately, mixed in a certain proportion to form a film solution, and deposited onto the surface of a ceramic support using a dip-coating method. Finally, the film is modified with silane to obtain the finished product. This invention separates powder preparation from membrane loading, resulting in a simple and easy-to-operate process with a short production cycle. The resulting ceramic membrane forms a silica network and a zinc oxide nanoflower bridging structure internally, and possesses a low surface energy hydrophobic interface, exhibiting excellent superhydrophobic, self-cleaning, and anti-fouling properties. The membrane adheres firmly and has good durability, making it suitable for large-scale production and widely applicable in water treatment scenarios.

Description

Technical Field

[0001] This invention belongs to the field of superhydrophobic technology, specifically relating to a superhydrophobic ceramic film based on zinc oxide nanoflowers and its preparation method. Background Technology

[0002] Superhydrophobic membrane materials have important applications in water treatment. For example, in membrane distillation and the treatment of oily wastewater, organic membranes are prone to swelling, aging, and degradation in high-temperature and oily environments, leading to decreased membrane performance and shortened service life. In contrast, inorganic ceramic membranes, with their advantages of high temperature resistance, organic solvent resistance, high mechanical strength, and good chemical stability, demonstrate superior applicability in these demanding processes and have therefore attracted widespread attention in the industry.

[0003] In the treatment of water-in-oil wastewater, even with superhydrophobic ceramic membranes, membrane fouling remains a key technical challenge. Membrane fouling leads to decreased membrane flux, reduced separation efficiency, and increased cleaning frequency, thereby increasing treatment costs and limiting the large-scale application of superhydrophobic ceramic membranes. To address this fouling problem, a common technique in the art is to construct a nano-zinc oxide filter layer on the ceramic membrane surface. Utilizing the hydrophobic properties, antibacterial properties, and high specific surface area of ​​nano-zinc oxide, the membrane's antifouling ability is improved, and its separation performance is enhanced.

[0004] Currently, existing methods for constructing nano-zinc oxide filtration layers on ceramic membrane surfaces mainly include chemical deposition and hydrothermal methods, with auxiliary methods such as sol-gel and sputtering. Among them, chemical deposition requires strict control of reaction concentration, pH value, and reaction temperature, and suffers from problems such as uneven coating thickness and weak adhesion to the ceramic membrane substrate. In addition, by-products are easily generated during the reaction, increasing subsequent processing costs. Hydrothermal methods require high temperature and high pressure conditions, have long reaction cycles, high energy consumption, and are difficult to achieve uniform coating of large tubular ceramic membranes, making the operation quite difficult. Coatings prepared by the sol-gel method are prone to cracking and peeling, exhibiting poor stability. Sputtering methods involve high equipment investment, complex operation processes, and poor economic efficiency for large-scale production.

[0005] Crucially, the existing methods mentioned above all have significant limitations when it comes to the superhydrophobic modification of large tubular ceramic membranes, which are widely used in industry: either the processing time is long and the production efficiency is low, making it difficult to meet the needs of large-scale production; or the operation process is complex and the equipment requirements are high, resulting in high operating costs, which further restricts the industrial promotion of superhydrophobic ceramic membranes in fields such as oily wastewater treatment.

[0006] In summary, existing technologies for addressing the fouling problem of superhydrophobic ceramic membranes suffer from drawbacks in practical applications, such as unstable coating performance, complex operation, long processing time, high cost, and difficulty in adapting to the large-scale production of large tubular ceramic membranes. Therefore, providing an efficient, low-cost, and scalable antifouling modification technology for superhydrophobic ceramic membranes has become a core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of poor coating stability, complicated and time-consuming process and difficulty in large-scale production in existing processes, and to provide a superhydrophobic ceramic film based on zinc oxide nanoflower balls and its preparation method.

[0008] The present invention proposes a method for preparing a superhydrophobic ceramic film based on zinc oxide nanoflowers, comprising the following steps: Tetraethoxysilane and anhydrous ethanol were mixed and stirred to obtain a mixture. Pretreated ammonia was added to the mixture to obtain a colloidal solution. A base solution was prepared by mixing deionized water and anhydrous ethanol. Zinc oxide nanoflower ball powder was mixed with the base solution and then dispersed in polyethylene glycol solution to obtain a dispersion solution. A colloidal solution is added to the dispersion solution to obtain a membrane solution. The support is vertically immersed in the membrane solution. After standing, the sample is pulled out of the membrane solution to obtain a ceramic membrane sample. The ceramic membrane sample was processed to obtain a ceramic membrane. The modified solution was prepared by mixing n-octyltriethoxysilane with anhydrous ethanol. The ceramic membrane was then immersed in the modified solution to obtain a superhydrophobic ceramic membrane.

[0009] Preferably, the zinc oxide nano-flower ball powder is specifically: Mix deionized water and ethylene glycol, add zinc acetate and urea, and stir magnetically at room temperature; The uniformly dispersed solution was reacted at a set temperature to obtain a zinc oxide precursor. The zinc oxide precursor was centrifuged, washed with deionized water and anhydrous ethanol, and dried at a set temperature to obtain precursor powder. The precursor powder was calcined and annealed to obtain zinc oxide nanoflower ball powder.

[0010] Preferably, the volume ratio of deionized water to ethylene glycol and the mass ratio of zinc acetate to urea are both 1:3, and the mixture is magnetically stirred at room temperature for 30 to 40 minutes. The uniformly dispersed solution was reacted at 90℃~110℃ for 3h~5h to obtain the zinc oxide precursor; The precursor powder was obtained by washing with deionized water and anhydrous ethanol and drying at 50℃~70℃ for 8h~12h. Zinc oxide nano-flower ball powder was obtained by calcining the precursor powder at 350℃~450℃ and annealing it for 2h~4h.

[0011] Preferably, the method for preparing the dispersion solution is as follows: A base solution was prepared by mixing deionized water and anhydrous ethanol. Zinc oxide nanoflower ball powder was mixed with the base solution at a concentration of 3 mg / mL to 5 mg / mL. The mixture was ultrasonically vibrated for 30 min to 40 min. A polyethylene glycol solution with a mass fraction of 0.05% to 0.15% was then added dropwise to disperse the mixture and obtain a dispersion solution. The volume ratio of deionized water to anhydrous ethanol is 1:9.

[0012] Preferably, the step of adding a colloidal solution to the dispersion solution to obtain a film solution specifically involves: Add a colloidal solution to the dispersion at a volume ratio of 19:1, while maintaining the pH of the solution at neutral or slightly alkaline.

[0013] Preferably, the step of vertically immersing the ceramic membrane support in the membrane solution, allowing it to stand, and then pulling the sample out of the membrane solution to obtain the ceramic membrane sample specifically involves: The ceramic membrane support is vertically immersed in the membrane solution and left to stand for 30 to 60 seconds. The sample is then pulled out of the membrane solution at a speed of 2 cm / min to 4 cm / min to obtain the ceramic membrane sample.

[0014] Preferably, the process of processing the ceramic membrane sample to obtain the ceramic membrane specifically involves: The ceramic membrane sample was naturally dried in a ventilated place at room temperature for 1 to 2 hours, then dried at 90℃ to 110℃ for 3 to 4 hours. The sample was then cured at 140℃ to 170℃ and kept at that temperature for 2 to 4 hours to obtain the ceramic membrane.

[0015] Preferably, the step of mixing n-octyltriethoxysilane with anhydrous ethanol to prepare a modification solution, and then immersing the ceramic membrane in the modification solution to obtain a superhydrophobic ceramic membrane, specifically involves: Octyltriethoxysilane was added to anhydrous ethanol to prepare a modification solution. The ceramic membrane was immersed in the modification solution and stirred with a fixed magnetic force. The modified ceramic membrane was rinsed sequentially with ethanol, a mixture of ethanol and deionized water, and deionized water. The modified ceramic membrane was dried to obtain a superhydrophobic ceramic membrane.

[0016] Preferably, the magnetic stirring speed is fixed at 145 r / min to 155 r / min, the temperature is 38℃ to 42℃, and the reaction time is 10h to 12h; the modified ceramic membrane is dried at 80℃ to 90℃ for 5h to 8h to obtain a superhydrophobic ceramic membrane; the volume ratio of the ethanol and deionized water mixture is 1:1.

[0017] The present invention proposes a superhydrophobic ceramic membrane based on zinc oxide nanofloral balls, which is prepared by the aforementioned method for preparing a superhydrophobic ceramic membrane based on zinc oxide nanofloral balls.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: This invention proposes a method for preparing superhydrophobic ceramic membranes based on zinc oxide nanospheres. First, the preparation of zinc oxide nanosphere powder is separated from membrane loading. A pre-synthesized powder is directly dispersed, replacing in-situ growth processes such as hydrothermal and chemical deposition. This avoids the high-temperature, high-pressure environment and long reaction cycle required for in-situ reactions, significantly shortening production time, reducing process complexity and equipment costs, and making it suitable for industrial operation of large-scale tubular membranes. Second, a silicon-oxygen network formed by the hydrolysis of tetraethoxysilane is used as a bridging medium. The silica sol and zinc oxide nanospheres in the membrane solution are uniformly composited. In the membrane layer formed after dip-coating, the silicon-oxygen network and zinc oxide nanospheres form a stable bridging structure, significantly improving the adhesion between the membrane layer and the ceramic support. This solves the problems of easy coating peeling and poor stability in existing coatings, ensuring membrane durability. Third, the dip-coating process achieves membrane loading. The support only needs to be immersed in the membrane solution and then allowed to stand before being pulled out. The operation is simple and controllable, requiring no complex equipment, and can be adapted to tubular ceramic membranes of different specifications, solving the pain point of existing processes being difficult to scale up. Finally, by modifying the membrane surface with n-octyltriethoxysilane, a low surface energy alkane-silicon interface is grafted onto the membrane surface. This interface works synergistically with the micro-nano rough structure constructed from zinc oxide nanospheres to achieve stable superhydrophobic properties. Simultaneously, the photocatalytic properties of zinc oxide can further enhance the membrane's self-cleaning ability and alleviate membrane fouling. This approach balances production efficiency, scalability, and membrane stability, effectively addressing the shortcomings of existing technologies.

[0019] Furthermore, by combining solvothermal reaction with calcination annealing, zinc oxide nanoflower-like powder with uniform morphology and high purity is prepared, realizing the separation of powder synthesis and film loading processes. This avoids the shortcomings of in-situ growth processes, which are complicated, time-consuming, and difficult to adapt to large-scale production, and significantly shortens the overall production process. At the same time, the zinc oxide nanoflower-like powder obtained by this method has a typical hierarchical rough structure, providing a key morphological basis for the subsequent construction of superhydrophobic interfaces. Moreover, the powder can form a stable bridge with the silicon-oxygen network, significantly improving the adhesion between the film and the substrate and the consistency of product performance, ensuring the stability and durability of the superhydrophobic ceramic film.

[0020] The present invention proposes a superhydrophobic ceramic membrane based on zinc oxide nanoflowers, which is prepared by the aforementioned method. The silicon-oxygen network in the membrane layer is strongly bridged with the zinc oxide nanoflowers. The surface has both micro-nano rough structure and low surface energy interface. It has stable superhydrophobic properties, excellent anti-fouling and durability, and is suitable for large-scale industrial applications. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the surface of the modified ceramic film prepared according to the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0024] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0025] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0026] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0027] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0028] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0029] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0030] This invention aims to overcome the shortcomings of existing tubular ceramic membranes in terms of antifouling performance. It utilizes zinc oxide nanosphere gel to prepare a superior self-cleaning superhydrophobic ceramic membrane at a lower curing temperature. The superhydrophobic ceramic membrane is prepared by dip-coating and possesses self-cleaning functionality. The dip-coating method separates the preparation and loading of the zinc oxide nanosphere material, optimizing the production process, shortening production time, and reducing operating costs. The method is described in detail below: The present invention proposes a method for preparing a superhydrophobic ceramic film based on zinc oxide nanoflowers, comprising the following steps: Step 1: Mix tetraethoxysilane with anhydrous ethanol to obtain a mixture. Add pretreated ammonia to the mixture to obtain a colloidal solution. The pretreated ammonia is ammonia that has been pre-diluted with deionized water.

[0031] Step 2: Prepare a base solution by mixing deionized water and anhydrous ethanol. Mix the zinc oxide nanoflower ball powder with the base solution and then add polyethylene glycol solution to disperse the powder, thus obtaining a dispersion solution. The zinc oxide nanoparticle powder is specifically: Mix deionized water and ethylene glycol, add zinc acetate and urea, and stir magnetically at room temperature; The uniformly dispersed solution was reacted at a set temperature to obtain a zinc oxide precursor. The zinc oxide precursor was centrifuged, washed with deionized water and anhydrous ethanol, and dried at a set temperature to obtain precursor powder. The precursor powder was calcined and annealed to obtain zinc oxide nanoflower ball powder.

[0032] The volume ratio of deionized water to ethylene glycol and the mass ratio of zinc acetate to urea were both 1:3. The mixture was magnetically stirred at room temperature for 30-40 minutes. The uniformly dispersed solution was reacted at 90-110°C for 3-5 hours to obtain a zinc oxide precursor. After washing with deionized water and anhydrous ethanol, the precursor powder was dried at 50-70°C for 8-12 hours to obtain the precursor powder. The precursor powder was calcined at 350-450°C and annealed for 2-4 hours to obtain zinc oxide nanoflower ball powder.

[0033] The dispersion solution is specifically: A base solution was prepared by mixing deionized water and anhydrous ethanol. Zinc oxide nanoflower ball powder was mixed with the base solution at a concentration of 3 mg / mL to 5 mg / mL. The mixture was ultrasonically vibrated for 30 min to 40 min. A polyethylene glycol solution with a mass fraction of 0.05% to 0.15% was then added dropwise to disperse the mixture and obtain a dispersion solution. The volume ratio of deionized water to anhydrous ethanol is 1:9.

[0034] Step 3: Add colloidal solution to dispersion solution to obtain membrane solution. Vertically immerse ceramic membrane support into membrane solution. After standing, pull sample out of membrane solution to obtain ceramic membrane sample. The process of adding a colloidal solution to the dispersion solution to obtain a membrane solution specifically involves: Add a colloidal solution to the dispersion at a volume ratio of 19:1, while maintaining the pH of the solution at neutral or slightly alkaline.

[0035] The process of vertically immersing the ceramic membrane support in the membrane solution, allowing it to stand, and then pulling the sample out of the membrane solution to obtain the ceramic membrane sample is as follows: The ceramic membrane support is vertically immersed in the membrane solution and left to stand for 30 to 60 seconds. The sample is then pulled out of the membrane solution at a speed of 2 cm / min to 4 cm / min to obtain the ceramic membrane sample.

[0036] Step 4: The ceramic membrane sample is processed to obtain a ceramic membrane. Octyltriethoxysilane is mixed with anhydrous ethanol to prepare a modification solution. The ceramic membrane is immersed in the modification solution for treatment to obtain a superhydrophobic ceramic membrane.

[0037] The process of processing the ceramic membrane sample to obtain the ceramic membrane specifically involves: The ceramic membrane sample was naturally dried in a ventilated place at room temperature for 1 to 2 hours, then dried at 90℃ to 110℃ for 3 to 4 hours. The sample was then cured at 140℃ to 170℃ and kept at that temperature for 2 to 4 hours to obtain the ceramic membrane.

[0038] The superhydrophobic ceramic membrane is specifically: Octyltriethoxysilane was added to anhydrous ethanol to prepare a modification solution. The ceramic membrane was immersed in the modification solution and stirred with a fixed magnetic force. The modified ceramic membrane was rinsed sequentially with ethanol, a mixture of ethanol and deionized water, and deionized water. The modified ceramic membrane was dried to obtain a superhydrophobic ceramic membrane.

[0039] The magnetic stirring speed was fixed at 145 r / min to 155 r / min, the temperature was 38℃ to 42℃, and the reaction time was 10h to 12h. The modified ceramic membrane was dried at 80℃ to 90℃ for 5h to 8h to obtain a superhydrophobic ceramic membrane. The volume ratio of the ethanol and deionized water mixture was 1:1.

[0040] Example 1 Pre-treatments such as grinding and wiping were performed on the surface of the support to remove imperfections. The support was ultrasonically treated for 5 min each in anhydrous ethanol and deionized water. 100 mL of deionized water and 300 mL of ethylene glycol were mixed, and 10 g of zinc acetate and 30 g of urea were added. The mixture was magnetically stirred at room temperature for 40 min. The uniformly dispersed solution was heated in an oven at 110 °C for 4 h. The obtained zinc oxide precursor was centrifuged, washed three times with deionized water and anhydrous ethanol, and dried in an oven at 70 °C for 9 h to obtain precursor powder. Finally, the precursor powder was calcined in a muffle furnace at 450 °C for 2 h in air to obtain zinc oxide nanoflower ball powder.

[0041] Tetraethoxysilane (TEOS, > 99%) was mixed with anhydrous ethanol and magnetically stirred for 12 min at room temperature; a colloidal solution was obtained by dropwise addition of 0.01 M ammonia solution pre-diluted with deionized water.

[0042] A solution was prepared by mixing 5 ml of deionized water and 45 ml of anhydrous ethanol at a volume ratio of 1:9. The obtained zinc oxide nanoparticle powder was then mixed with this solution at a concentration of 3 mg / mL. The mixture was ultrasonically vibrated for 33 min, and then dispersed by adding a 0.1% (w / w) polyethylene glycol solution dropwise.

[0043] Slowly add 2 ml of gel solution to 38 ml of dispersion, at a volume ratio of 19:1. Maintain the pH of the solution at a slightly alkaline level throughout the process.

[0044] The pretreated support was vertically immersed in the liquid and allowed to stand for 30 seconds. The sample was then slowly pulled out of the membrane liquid at a speed of 2.5 cm / min.

[0045] The ceramic film sample was air-dried at room temperature in a ventilated area for 1 hour. It was then placed in a 100℃ oven for 4 hours. Finally, the sample was placed in a muffle furnace and cured at 150℃ in air for 2 hours.

[0046] A modification solution was prepared by adding 6.5 mL of n-octyltriethoxysilane to 100 mL of anhydrous ethanol. The ceramic membrane was immersed in the modification solution, and the magnetic stirring speed was fixed at 150 r / min, the temperature at 40℃, and the reaction was carried out for 12 h. The modified ceramic membrane was then rinsed twice each with ethanol, a mixture of 50% ethanol and deionized water, and deionized water. Finally, the modified ceramic membrane was dried in an oven at 85℃ for 5 h.

[0047] Example 2 Pre-treatments such as grinding and wiping were performed on the surface of the support to remove imperfections. The support was ultrasonically treated for 8 min each in anhydrous ethanol and deionized water. 20 mL of deionized water and 60 mL of ethylene glycol were mixed, and 1 g of zinc acetate and 3 g of urea were added. The mixture was magnetically stirred at room temperature for 35 min. The uniformly dispersed solution was heated in an oven at 100 °C for 3 h. The obtained zinc oxide precursor was centrifuged, washed three times with deionized water and anhydrous ethanol, and dried in an oven at 55 °C for 8 h to obtain precursor powder. Finally, the precursor powder was calcined in a muffle furnace at 400 °C for 2.5 h in air to obtain zinc oxide nano-flower ball powder.

[0048] Tetraethoxysilane (TEOS, > 99%) was mixed with anhydrous ethanol and magnetically stirred for 12 min at room temperature; a colloidal solution was obtained by dropwise addition of 0.05 M ammonia solution pre-diluted with deionized water.

[0049] A solution was prepared by mixing 3 ml of deionized water and 27 ml of anhydrous ethanol at a volume ratio of 1:9. The obtained zinc oxide nanoparticle powder was then mixed with this solution at a concentration of 4 mg / mL. The mixture was ultrasonically vibrated for 38 min, and then dispersed by adding a 0.15% (w / w) polyethylene glycol solution dropwise.

[0050] Slowly add 3 ml of gel solution to 57 ml of dispersion, at a volume ratio of 19:1. Maintain the pH of the solution at a slightly alkaline level throughout the process.

[0051] The pretreated support was vertically immersed in the liquid and allowed to stand for 50 seconds. The sample was then slowly pulled out of the membrane liquid at a speed of 3 cm / min.

[0052] The ceramic film sample was air-dried at room temperature in a ventilated area for 1 hour. It was then placed in a 95°C oven for 3.5 hours. Finally, the sample was placed in a muffle furnace and cured at 150°C in air for 3 hours.

[0053] A modification solution was prepared by adding 5.2 mL of n-octyltriethoxysilane to 80 mL of anhydrous ethanol. The ceramic membrane was immersed in the modification solution, and the magnetic stirring speed was fixed at 145 r / min, the temperature at 40 °C, and the reaction was carried out for 12 h. The modified ceramic membrane was then rinsed twice each with ethanol, a mixture of 50% ethanol and deionized water, and deionized water. Finally, the modified ceramic membrane was dried in an 80 °C oven for 6 h.

[0054] Example 3 Pre-treatments such as grinding and wiping were performed on the surface of the support to remove imperfections. The support was ultrasonically treated in anhydrous ethanol and deionized water for 10 min each. 25 mL of deionized water and 75 mL of ethylene glycol were mixed, and 4 g of zinc acetate and 12 g of urea were added. The mixture was magnetically stirred at room temperature for 32 min. The uniformly dispersed solution was heated in a 95 °C oven for 5 h. The obtained zinc oxide precursor was centrifuged, washed three times with deionized water and anhydrous ethanol, and dried in a 60 °C oven for 10 h to obtain precursor powder. Finally, it was calcined in a muffle furnace at 380 °C for 3.5 h in air to obtain zinc oxide nano-flower ball powder.

[0055] Tetraethoxysilane (TEOS, > 99%) was mixed with anhydrous ethanol and magnetically stirred for 10 min at room temperature; a colloidal solution was obtained by dropwise addition of 0.03 M ammonia solution pre-diluted with deionized water.

[0056] A solution was prepared by mixing 8 ml of deionized water and 72 ml of anhydrous ethanol at a volume ratio of 1:9. The obtained zinc oxide nanoparticle powder was then mixed with this solution at a concentration of 4.5 mg / mL. The mixture was ultrasonically vibrated for 35 min, and then dispersed by adding a 0.05% (w / w) polyethylene glycol solution dropwise.

[0057] Slowly add 4 ml of gel solution to 76 ml of dispersion, at a volume ratio of 19:1. Maintain the solution pH at a slightly alkaline level throughout the process. Vertically immerse the pretreated support in the solution and allow it to stand for 50 seconds. Slowly pull the sample out of the membrane solution at a speed of 4 cm / min.

[0058] The ceramic film sample was air-dried at room temperature in a ventilated area for 2 hours. It was then placed in a 100℃ oven for 4 hours. Finally, the sample was placed in a muffle furnace and cured at 140℃ in air for 2 hours.

[0059] A modification solution was prepared by adding 5.85 mL of n-octyltriethoxysilane to 90 mL of anhydrous ethanol. The ceramic membrane was immersed in the modification solution, and the magnetic stirring speed was fixed at 150 r / min, the temperature at 38℃, and the reaction was carried out for 11 h. The modified ceramic membrane was then rinsed twice each with ethanol, a mixture of 50% ethanol and deionized water, and deionized water. Finally, the modified ceramic membrane was dried in an oven at 85℃ for 8 h.

[0060] Example 4 Pre-treatments such as grinding and wiping were performed on the surface of the support to remove imperfections. The support was ultrasonically treated in anhydrous ethanol and deionized water for 10 min each. 30 mL of deionized water and 90 mL of ethylene glycol were mixed, and 1.8 g of zinc acetate and 5.4 g of urea were added. The mixture was magnetically stirred at room temperature for 35 min. The uniformly dispersed solution was placed in an oven at 100 °C and heated for 4 h. The obtained zinc oxide precursor was centrifuged, washed three times repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 65 °C for 8 h to obtain precursor powder. Finally, it was calcined in a muffle furnace at 350 °C in air and annealed for 3 h to obtain zinc oxide nano-flower ball powder.

[0061] Tetraethoxysilane (TEOS, > 99%) was mixed with anhydrous ethanol and magnetically stirred for 9 min at room temperature; a colloidal solution was obtained by dropwise addition of 0.02 M ammonia solution pre-diluted with deionized water.

[0062] Prepare a solution by mixing 10 ml of deionized water and 90 ml of anhydrous ethanol at a volume ratio of 1:9. Mix the obtained zinc oxide nanoparticle powder with this solution at a concentration of 3 mg / mL. Sonicate the mixture for 30 min, then disperse it by adding a 0.08% (w / w) polyethylene glycol solution dropwise.

[0063] Slowly add 5 ml of gel solution to 95 ml of dispersion, at a volume ratio of 19:1. Maintain the solution pH at a slightly alkaline level throughout the process.

[0064] The pretreated support was vertically immersed in the liquid and allowed to stand for 60 seconds. The sample was then slowly pulled out of the membrane liquid at a speed of 3.5 cm / min.

[0065] The ceramic film sample was air-dried at room temperature in a ventilated area for 1 hour. It was then placed in a 90℃ oven for 4 hours. Finally, the sample was placed in a muffle furnace and cured at 160℃ in air for 4 hours.

[0066] A modification solution was prepared by adding 6.5 mL of n-octyltriethoxysilane to 100 mL of anhydrous ethanol. The ceramic membrane was immersed in the modification solution, and the magnetic stirring speed was fixed at 155 r / min, the temperature at 42℃, and the reaction was carried out for 10 h. The modified ceramic membrane was then rinsed twice each with ethanol, a mixture of 50% ethanol and deionized water, and deionized water. Finally, the modified ceramic membrane was dried in an 80℃ oven for 5 h.

[0067] Example 5 Pre-treatments such as grinding and wiping were performed on the surface of the support to remove imperfections. The support was ultrasonically treated in anhydrous ethanol and deionized water for 10 min each. 35 mL of deionized water and 105 mL of ethylene glycol were mixed, and 2.5 g of zinc acetate and 7.5 g of urea were added. The mixture was magnetically stirred at room temperature for 38 min. The uniformly dispersed solution was placed in an oven at 110 °C and heated for 4 h. The obtained zinc oxide precursor was centrifuged, washed three times repeatedly with deionized water and anhydrous ethanol, and dried in an oven at 60 °C for 12 h to obtain precursor powder. Finally, it was calcined in a muffle furnace at 400 °C in air and annealed for 2 h to obtain zinc oxide nano-flower ball powder.

[0068] Tetraethoxysilane (TEOS, > 99%) was mixed with anhydrous ethanol and magnetically stirred for 8 min at room temperature; a colloidal solution was obtained by dropwise addition of 0.04 M ammonia solution pre-diluted with deionized water.

[0069] Prepare a solution by mixing 1 ml of deionized water and 9 ml of anhydrous ethanol at a volume ratio of 1:9. Mix the obtained zinc oxide nanoparticle powder with this solution at a concentration of 4 mg / mL. Sonicate the mixture for 40 min, then disperse it by adding a 0.13% (w / w) polyethylene glycol solution dropwise.

[0070] Slowly add 6 ml of gel solution to 114 ml of dispersion, at a volume ratio of 19:1. Maintain the solution pH at a slightly alkaline level throughout the process. The pretreated support was vertically immersed in the liquid and allowed to stand for 30 seconds. The sample was then slowly pulled out of the membrane liquid at a speed of 4 cm / min.

[0071] The ceramic film sample was air-dried at room temperature in a ventilated area for 1.5 hours. It was then placed in a 110℃ oven for 3 hours. Finally, the sample was placed in a muffle furnace and cured at 170℃ in air for 2 hours.

[0072] A modification solution was prepared by adding 7.8 mL of n-octyltriethoxysilane to 120 mL of anhydrous ethanol. The ceramic membrane was immersed in the modification solution, and the magnetic stirring speed was fixed at 150 r / min, the temperature at 40℃, and the reaction was carried out for 11 h. The modified ceramic membrane was then rinsed twice each with ethanol, a mixture of 50% ethanol and deionized water, and deionized water. Finally, the modified ceramic membrane was dried in an oven at 85℃ for 7 h.

[0073] Example 6 Pre-treatments such as grinding and wiping were performed on the surface of the support to remove imperfections. The support was ultrasonically treated in anhydrous ethanol and deionized water for 10 min each. 20 mL of deionized water and 60 mL of ethylene glycol were mixed, and 1 g of zinc acetate and 3 g of urea were added. The mixture was magnetically stirred at room temperature for 30 min. The uniformly dispersed solution was placed in a 90 °C oven and heated for 4 h. The obtained zinc oxide precursor was centrifuged, washed three times repeatedly with deionized water and anhydrous ethanol, and dried in a 50 °C oven for 8 h to obtain precursor powder. Finally, it was calcined in a muffle furnace at 350 °C in air and annealed for 4 h to obtain zinc oxide nano-flower ball powder.

[0074] Tetraethoxysilane (TEOS, > 99%) was mixed with anhydrous ethanol and magnetically stirred for 12 min at room temperature; a colloidal solution was obtained by dropwise addition of 0.03 M ammonia solution pre-diluted with deionized water.

[0075] Prepare a solution by mixing 2 ml of deionized water and 18 ml of anhydrous ethanol at a volume ratio of 1:9. Mix the obtained zinc oxide nanoparticle powder with this solution at a concentration of 5 mg / mL. Sonicate the mixture for 40 min, then disperse it by adding a 0.1% (w / w) polyethylene glycol solution dropwise.

[0076] Slowly add 7 ml of gel solution to 133 ml of dispersion, at a volume ratio of 19:1. Maintain the solution pH at a slightly alkaline level throughout the process. The pretreated support was vertically immersed in the liquid and allowed to stand for 40 seconds. The sample was then slowly pulled out of the membrane liquid at a speed of 2 cm / min.

[0077] The ceramic film sample was air-dried at room temperature in a ventilated area for 1 hour. It was then placed in a 100℃ oven for 4 hours. Finally, the sample was placed in a muffle furnace and cured at 150℃ in air for 2 hours.

[0078] A modification solution was prepared by adding 8.45 mL of n-octyltriethoxysilane to 130 mL of anhydrous ethanol. The ceramic membrane was immersed in the modification solution, and the magnetic stirring speed was fixed at 145 r / min, the temperature at 40 °C, and the reaction was carried out for 12 h. The modified ceramic membrane was then rinsed twice each with ethanol, a mixture of 50% ethanol and deionized water, and deionized water. Finally, the modified ceramic membrane was dried in a 90 °C oven for 6 h.

[0079] Table 1 Effects of the Examples

[0080] Table 1 shows the water contact angle test results of different ceramic membranes. The contact angle of the untreated hydrophilic ceramic membrane is 0°, and the water droplets spread completely on the surface, exhibiting a completely hydrophilic state. The contact angles of the ceramic membranes prepared in the six embodiments of this invention all reach more than 150°, meeting the criteria for superhydrophobic interfaces. This indicates that the technical solution of this invention successfully modifies the hydrophilic ceramic membrane into a stable superhydrophobic surface, which can significantly reduce pollutant adhesion and improve the antifouling performance of the membrane, verifying the effectiveness and universality of the technical solution of this invention.

[0081] In this invention, during the preparation of the zinc oxide nanosphere membrane solution, adjusting the membrane solution concentration and the type of zinc oxide nanospheres can control the microstructure of the modified ceramic membrane surface, thereby controlling the contact angle and oil-water separation characteristics of the ceramic membrane.

[0082] Figure 1 The image shows a scanning electron microscope (SEM) image of the modified ceramic membrane prepared according to the present invention. As can be seen from the image, the surface of the ceramic membrane is completely covered by a uniform and dense zinc oxide nanoflower-shaped membrane layer, forming a typical micro-nano hierarchical rough structure with no obvious defects or exposed substrate. This indicates that the dip-coating process of the present invention can achieve uniform loading of the membrane layer. This rough structure provides a key structural basis for the superhydrophobic properties of the membrane.

[0083] In summary, this invention provides a method for preparing a superhydrophobic ceramic membrane based on zinc oxide nanospheres. The superhydrophobic ceramic membrane prepared by this method has two important structural features: ① the membrane layer is bridged by a silicon-oxygen network and hollow zinc oxide nanospheres; ② the ceramic membrane surface has a low surface energy interface with alkane-silicon grafts. Due to the photocatalytic properties of zinc oxide, porous ceramics using zinc oxide nanospheres as the membrane layer not only possess high porosity and superhydrophobic surface function, but also hold promise for improving the durability and self-cleaning properties of ceramic membranes. The simple and easily implemented dip-coating method for membrane construction avoids the complexity and time-consuming in-situ zinc oxide growth process, significantly shortening the production time.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls, characterized in that, Includes the following steps: Tetraethoxysilane and anhydrous ethanol were mixed and stirred to obtain a mixture. Pretreated ammonia was added to the mixture to obtain a colloidal solution. A base solution was prepared by mixing deionized water and anhydrous ethanol. Zinc oxide nanoflower ball powder was mixed with the base solution and then dispersed in polyethylene glycol solution to obtain a dispersion solution. A colloidal solution is added to the dispersion solution to obtain a membrane solution. The support is vertically immersed in the membrane solution. After standing, the sample is pulled out of the membrane solution to obtain a ceramic membrane sample. The ceramic membrane sample was processed to obtain a ceramic membrane. The modified solution was prepared by mixing n-octyltriethoxysilane with anhydrous ethanol. The ceramic membrane was then immersed in the modified solution to obtain a superhydrophobic ceramic membrane.

2. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 1, characterized in that, The zinc oxide nanoparticle powder is specifically: Mix deionized water and ethylene glycol, add zinc acetate and urea, and stir magnetically at room temperature; The uniformly dispersed solution was reacted at a set temperature to obtain a zinc oxide precursor. The zinc oxide precursor was centrifuged, washed with deionized water and anhydrous ethanol, and dried at a set temperature to obtain precursor powder. The precursor powder was calcined and annealed to obtain zinc oxide nanoflower ball powder.

3. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 2, characterized in that, The volume ratio of deionized water to ethylene glycol and the mass ratio of zinc acetate to urea were both 1:

3. The mixture was magnetically stirred at room temperature for 30 to 40 minutes. The uniformly dispersed solution was reacted at 90℃~110℃ for 3h~5h to obtain the zinc oxide precursor; The precursor powder was obtained by washing with deionized water and anhydrous ethanol and drying at 50℃~70℃ for 8h~12h. Zinc oxide nano-flower ball powder was obtained by calcining the precursor powder at 350℃~450℃ and annealing it for 2h~4h.

4. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 1, characterized in that, The method for preparing the dispersion solution is as follows: A base solution was prepared by mixing deionized water and anhydrous ethanol. Zinc oxide nanoflower ball powder was mixed with the base solution at a concentration of 3 mg / mL to 5 mg / mL. The mixture was ultrasonically vibrated for 30 min to 40 min. A polyethylene glycol solution with a mass fraction of 0.05% to 0.15% was then added dropwise to disperse the mixture and obtain a dispersion solution. The volume ratio of deionized water to anhydrous ethanol is 1:

9.

5. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 1, characterized in that, The process of adding a colloidal solution to the dispersion solution to obtain a membrane solution specifically involves: Add a colloidal solution to the dispersion at a volume ratio of 19:1, while maintaining the pH of the solution at neutral or slightly alkaline.

6. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 1, characterized in that, The process of vertically immersing the ceramic membrane support in the membrane solution, allowing it to stand, and then pulling the sample out of the membrane solution to obtain the ceramic membrane sample is as follows: The ceramic membrane support is vertically immersed in the membrane solution and left to stand for 30 to 60 seconds. The sample is then pulled out of the membrane solution at a speed of 2 cm / min to 4 cm / min to obtain the ceramic membrane sample.

7. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 1, characterized in that, The process of processing the ceramic membrane sample to obtain the ceramic membrane specifically involves: The ceramic membrane sample was naturally dried in a ventilated place at room temperature for 1 to 2 hours, then dried at 90℃ to 110℃ for 3 to 4 hours. The sample was then cured at 140℃ to 170℃ and kept at that temperature for 2 to 4 hours to obtain the ceramic membrane.

8. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 1, characterized in that, The process involves mixing n-octyltriethoxysilane with anhydrous ethanol to prepare a modification solution, then immersing the ceramic membrane in the modification solution for treatment to obtain a superhydrophobic ceramic membrane. Specifically: Octyltriethoxysilane was added to anhydrous ethanol to prepare a modification solution. The ceramic membrane was immersed in the modification solution and stirred with a fixed magnetic force. The modified ceramic membrane was rinsed sequentially with ethanol, a mixture of ethanol and deionized water, and deionized water. The modified ceramic membrane was dried to obtain a superhydrophobic ceramic membrane.

9. The method for preparing a superhydrophobic ceramic film based on zinc oxide nanofloral balls according to claim 8, characterized in that, The magnetic stirring speed was fixed at 145 r / min ~ 155 r / min, the temperature was 38℃ ~ 42℃, and the reaction time was 10h ~ 12h. The modified ceramic membrane was dried at 80℃ ~ 90℃ for 5h ~ 8h to obtain a superhydrophobic ceramic membrane. The volume ratio of the ethanol and deionized water mixture was 1:

1.

10. A superhydrophobic ceramic membrane based on zinc oxide nanofloral balls, characterized in that, The superhydrophobic ceramic membrane based on zinc oxide nanoflowers, as described in any one of claims 1 to 9, was prepared.

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