A rare earth doped antibacterial nano ceramic membrane and a preparation method and application thereof

Abstract

This invention discloses a rare-earth-doped antibacterial nanoceramic membrane, its preparation method, and its application, relating to the field of water treatment technology. The invention discloses an antibacterial nanoceramic membrane comprising an Al2O3 ceramic substrate and a membrane layer attached to the surface of the Al2O3 ceramic substrate; the membrane layer is obtained by coating the surface of the Al2O3 ceramic substrate with a membrane slurry and then sintering it; the membrane slurry includes ZrO2 powder and a rare-earth antibacterial agent, wherein the rare-earth antibacterial agent is a CeO2-La2O3 composite oxide. The antibacterial nanoceramic membrane prepared by this invention adopts a composite structure of an Al2O3 ceramic substrate and a rare-earth-doped ZrO₂ membrane layer; the Al2O3 substrate ensures the mechanical support performance of the membrane, while the membrane layer serves as a functional layer to achieve high-precision filtration and antibacterial functions. The membrane layer is obtained by sintering a membrane slurry containing a rare-earth antibacterial agent and ZrO₂ powder, solving the problems of easy detachment and excessive leaching of the antibacterial agent, and achieving a balance between mechanical and antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a rare earth-doped antibacterial nanoceramic membrane, its preparation method, and its application. Background Technology

[0002] Traditional tap water production processes involve coagulation, sedimentation, filtration, and disinfection, which remove most suspended solids and bacteria from the water. However, due to pollution of source water, traditional processes are gradually proving insufficient. Furthermore, chlorination disinfection can produce trihalomethanes. Using ceramic membrane technology for water treatment can effectively solve this problem, offering advantages such as lower chemical dosage, smaller footprint, energy efficiency, and ease of management and maintenance. Nano-ceramic membranes, with their small pore size (typically <100nm), high filtration accuracy, good chemical stability, high temperature resistance, and strong anti-fouling capabilities, have become the core material for the fine filtration stage of direct drinking water, effectively removing bacteria, viruses, colloids, and large molecular organic matter from the water.

[0003] However, the existing nano-ceramic membranes have the following technical bottlenecks in the application of direct drinking water systems: (1) The problem of biological pollution is prominent: Although the surface of the nano-ceramic membrane is smooth, after long-term use, bacteria in the water will still attach to and multiply on the membrane surface, forming a biofilm, which leads to a decrease in membrane flux (flux decay rate > 30% / month), an increase in cleaning frequency, and a shortened service life; (2) The antibacterial modification technology is immature: The existing antibacterial ceramic membranes mostly use physical coating to load antibacterial agents (such as silver nanoparticles, TiO2) onto the membrane surface, but the antibacterial agents are not firmly bound, are easy to fall off (dissolution amount > 0.1mg / L), and have a narrow antibacterial range (only effective against...). (3) It is difficult to balance mechanical properties and antibacterial properties: In order to improve the antibacterial effect, excessive addition of antibacterial components will lead to a decrease in the density of ceramic membrane and a decrease in fracture strength (<20MPa), which makes it easy to break under water pressure and cannot meet the long-term operation requirements of direct drinking water system; (4) The preparation process is complicated and costly: The preparation of existing antibacterial nano-ceramic membranes mostly adopts complex processes such as sol-gel method and vapor deposition method, which have large equipment investment and long production cycle (>24h / batch), and the pilot production cost is >500 yuan / m 2 (5) Poor system adaptability: The component design of the antibacterial ceramic membrane is unreasonable, the water flow is unevenly distributed on the membrane surface, resulting in low membrane utilization. In addition, the installation method of the membrane component is incompatible with the existing direct drinking water system, and the system needs to be significantly modified. Summary of the Invention

[0004] The purpose of this invention is to provide a rare earth-doped antibacterial nanoceramic membrane, its preparation method, and its application, thereby solving the following technical problems:

[0005] Existing nano-ceramic membranes have unsatisfactory antibacterial properties and the antibacterial materials are prone to detachment.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A rare earth-doped antibacterial nanoceramic membrane, comprising an Al2O3 ceramic substrate and a membrane layer attached to the surface of the Al2O3 ceramic substrate.

[0008] The film layer is prepared by coating a film layer slurry onto the surface of an Al2O3 ceramic substrate and then sintering it.

[0009] The membrane slurry includes ZrO2 powder and a rare earth antibacterial agent, wherein the rare earth antibacterial agent is a CeO2-La2O3 composite oxide.

[0010] As a further aspect of the present invention: the porosity of the Al2O3 ceramic substrate is 30-35%, and the average pore size is 2-5 μm;

[0011] The thickness of the film is 5-8 μm, and the average pore size is 50-80 nm.

[0012] As a further aspect of the present invention, the preparation method of Al2O3 ceramic substrate includes the following steps: mixing α-Al2O3 powder, PVA, glycerol and deionized water to form a slurry, casting it into shape, drying it and sintering it to obtain Al2O3 ceramic substrate.

[0013] As a further aspect of the present invention: the mass ratio of α-Al2O3 powder, PVA, glycerol, and deionized water is 60-70:4-6:1-3:25-35;

[0014] The specific steps for sintering are: sintering at 1200-1250℃ for 2-3 hours.

[0015] As a further aspect of the present invention, the preparation method of rare earth antibacterial agent includes the following steps: dissolving Ce(NO3)3˙6H2O and La(NO3)3˙6H2O in deionized water, adding urea, hydrothermal reaction, centrifugation, taking the precipitate, washing, drying, and calcining to obtain rare earth antibacterial agent.

[0016] As a further aspect of the present invention: the molar ratio of Ce(NO3)3˙6H2O, La(NO3)3˙6H2O, and urea is approximately 1.5-2.5:0.8-1.2:5-7;

[0017] The hydrothermal reaction is carried out at 180-200℃ for 8-10 hours; the calcination is carried out at 600-650℃ for 3-4 hours.

[0018] The preparation method of rare earth-doped antibacterial nanoceramic membrane includes the following steps: immersing an Al2O3 ceramic substrate in a membrane slurry and then sintering it to obtain a rare earth-doped antibacterial nanoceramic membrane.

[0019] As a further aspect of the present invention: the membrane slurry is prepared by mixing ZrO2 powder, rare earth antibacterial agent, PEG-400, and deionized water; wherein the ZrO2 powder accounts for 60-75% of the total mass of the membrane slurry; the rare earth antibacterial agent accounts for 0.5-2% of the total mass of the membrane slurry; and the PEG-400 accounts for 0.3-1% of the total mass of the membrane slurry.

[0020] The specific steps for sintering after impregnation treatment are as follows: immerse the Al2O3 ceramic substrate in the film slurry, remove it at a pulling speed of 5-8 cm / min, dry it, and sinter it at 1000-1050℃ for 1.5-2 hours.

[0021] The aforementioned antibacterial nano-ceramic membranes are applied to water treatment equipment or water treatment systems.

[0022] As a further aspect of the present invention: the water treatment equipment includes household direct drinking water machines and commercial direct drinking water equipment; the water treatment system is a direct drinking water system.

[0023] As a further aspect of the present invention: the water treatment system includes a pretreatment unit, a fine filtration unit, and a post-antibacterial unit arranged in sequence;

[0024] The pretreatment unit consists of PP cotton and activated carbon filter cartridges; it removes suspended solids, residual chlorine, and odors from the water.

[0025] The fine filtration unit is equipped with an antibacterial nano-ceramic membrane assembly; the antibacterial nano-ceramic membrane assembly is composed of antibacterial nano-ceramic membranes and silica gel meshes spaced apart; each antibacterial nano-ceramic membrane assembly contains 3-5 antibacterial nano-ceramic membranes; removing bacteria, viruses, and colloids from the water;

[0026] The post-antibacterial unit is filled with silver ion antibacterial particles to further ensure that the total number of bacteria in the effluent is <1 CFU / mL.

[0027] As a further aspect of the present invention: the antibacterial nano-ceramic membrane module adopts a cross-flow filtration method with a concentrate reflux ratio of 3:1.

[0028] As a further aspect of the present invention: the antibacterial nano-ceramic membrane module operates at a pressure of 0.1-0.15 MPa, a water temperature of 25°C, and a water production flux of 120-150 L / (m²). 2 ˙h).

[0029] As a further aspect of the present invention: a combination of "physical cleaning + chemical cleaning" is used for cleaning; the specific steps of physical cleaning are: compressed air back-blowing the membrane surface; the specific steps of chemical cleaning are: citric acid solution circulation cleaning, followed by rinsing with deionized water until neutral.

[0030] The beneficial effects of this invention are:

[0031] (1) Imparting spectral antibacterial properties to the film layer

[0032] This application describes the preparation of a lattice-doped CeO2-La2O3 composite rare earth antibacterial agent using cerium nitrate and lanthanum nitrate as raw materials via a hydrothermal-calcination method. Specifically, the oxygen vacancy defects in CeO2 can catalyze the generation of reactive oxygen species (ROS), which disrupt bacterial cell membranes; the alkaline surface of La2O3 inhibits bacterial adhesion, and La... 3+ It can interfere with microbial metabolism. Meanwhile, rare earth ions (Ce) 3+ / Ce 4+ La 3+ The adjustable valence state of TiO2 allows it to exert a broad-spectrum antibacterial effect by generating reactive oxygen species (ROS) even in the dark without ultraviolet light excitation, overcoming the limitation of TiO2's dependence on ultraviolet light.

[0033] (2) Achieving uniform loading and stable bonding of rare earth antibacterial materials in nano-ceramic membranes

[0034] The antibacterial nano-ceramic membrane prepared in this application adopts a composite structure of an Al2O3 ceramic substrate and a rare-earth-doped ZrO2 membrane layer. The Al2O3 substrate ensures the mechanical support performance of the membrane, while the membrane layer serves as a functional layer to achieve high-precision filtration and antibacterial functions. This application uses a blend of rare-earth antibacterial agent and ZrO2 powder as the membrane slurry, and achieves chemical bonding / lattice doping between the antibacterial agent and the ceramic membrane layer through impregnation and subsequent sintering. This solves the problems of easy detachment and excessive leaching of the antibacterial agent, with the leaching amount ≤0.01 mg / L. The ZrO2 added to the membrane slurry achieves a phase transformation toughening effect (tetragonal phase → monoclinic phase), which can compensate for the brittleness caused by rare-earth doping and maintain the mechanical properties of the material. This avoids the density reduction problem caused by the doping of antibacterial agents with a single material, achieving a balance between mechanical and antibacterial properties.

[0035] (3) Stable filtration performance

[0036] The rare-earth antibacterial nano-ceramic membrane prepared in this application is suitable for direct drinking water systems and provides corresponding integrated application solutions, achieving compatibility between the membrane module and existing direct drinking water systems. The membrane module has a cleaning cycle of ≥3 months and a service life of ≥2 years. The ceramic membrane exhibits an antibacterial rate of ≥99% against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, and after a 1000L water flux test, the antibacterial rate remains ≥98%, solving the biofouling problem of traditional ceramic membranes. It ensures that the effluent water quality meets the "Drinking Water Quality Standard" (CJ94-2020), with turbidity <0.1 NTU, total bacterial count <1 CFU / mL, and virus removal rate ≥99.9%, meeting the requirements for direct drinking water quality. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0038] Raw materials: Ce(NO3)3・6H2O, La(NO3)3˙6H2O (purity 99.9%, Shanghai Maclean Biochemical Technology Co., Ltd.); urea (analytical grade, Sinopharm Chemical Reagent Co., Ltd.); α-Al2O3 powder (particle size 1-3μm, purity 99%, Shandong Elpai Powder Technology Co., Ltd.); ZrO2 powder (particle size 50-100nm, purity 99.5%, Shanghai Aladdin Biochemical Technology Co., Ltd.); PVA, glycerol, PEG-400 (analytical grade, Sinopharm Chemical Reagent Co., Ltd.); deionized water (self-made, resistivity ≥18.2MΩ˙cm).

[0039] Equipment: Hydrothermal reactor (KH-200, Shanghai Kexing Instrument Co., Ltd.); High-speed centrifuge (TGL-16M, Hunan Xiangyi Laboratory Instrument Development Co., Ltd.); Muffle furnace (SX2-12-10, Shanghai Yifeng Electric Furnace Co., Ltd.); Casting machine (LY-600, Dongguan Liyu Machinery Co., Ltd.); Ultrasonic disperser (KQ-500DE, Kunshan Ultrasonic Instrument Co., Ltd.); Electronic universal testing machine (WDW-10, Jinan Shijin Group Co., Ltd.); Membrane flux analyzer (MPT-2, Suzhou Sujing Group Co., Ltd.); Antibacterial performance tester (KJ-201, Suzhou Kejian Testing Instrument Co., Ltd.).

[0040] Example 1: A method for preparing rare earth-doped antibacterial nanoceramic films, comprising the following steps:

[0041] S1: Preparation of rare earth antibacterial agent: 17.3g (0.04mol) Ce(NO3)3·6H2O, 9.7g (0.02mol) La(NO3)3·6H2O, and 200mL deionized water were placed in a beaker and stirred until completely dissolved to obtain a mixed solution; 7.2g (0.12mol) urea was added and stirred for 10min until the urea was completely dissolved to obtain a reaction solution; the reaction solution was transferred to the lining of a hydrothermal reactor (80% filling), the reactor lid was tightened, and the reactor was placed in an oven and reacted at 190℃ for 9h; After the reaction was completed, the oven was closed and the reactor was allowed to cool to room temperature. The liner was removed, and the solution was poured into centrifuge tubes and centrifuged at 8000 r / min for 15 min to obtain rare earth hydroxide precipitate. The rare earth hydroxide precipitate was washed three times with deionized water (100 mL of deionized water was added each time and centrifuged). The precipitate was then placed in a forced-air drying oven and dried at 80℃ for 4 h. The dried precipitate was placed in a muffle furnace, heated to 620℃, and kept at that temperature for 3.5 h. After natural cooling, the rare earth antibacterial agent was obtained, and the particle size was measured to be 35 nm by a laser particle size analyzer.

[0042] S2: Substrate preparation: 65g α-Al2O3 powder, 5g PVA, 2g glycerol, and 30g deionized water were placed in a planetary ball mill and milled at 300r / min for 2h to prepare a ceramic slurry; the ceramic slurry was poured into the material tank of a casting machine, the coating thickness was set to 0.25mm, the PET base film running speed was 10cm / min, and it was dried at 60℃ for 2h to obtain a ceramic green body;

[0043] The green body was peeled off from the PET base film, placed in a muffle furnace, heated to 1220℃, held for 2.5h, and cooled to room temperature after sintering to obtain an Al2O3 ceramic substrate (diameter 120mm, thickness 0.2mm, porosity 32%, average pore size 3μm).

[0044] S3: Membrane coating: Place 74g ZrO2 powder, 0.5g rare earth antibacterial agent, 0.5g PEG-400 and 25g deionized water into a beaker and disperse it for 30 minutes using an ultrasonic disperser (300W) to prepare a membrane slurry;

[0045] An Al2O3 ceramic substrate was vertically immersed in the film slurry and held for 10 seconds. It was then pulled out at a speed of 6 cm / min and dried at 80°C for 1 hour. The dried substrate was then placed in a muffle furnace, heated to 1020°C, held for 1.8 hours, and cooled to obtain a rare earth antibacterial nano-ceramic film (film thickness 6 μm, average pore size 65 nm).

[0046] Example 2: A method for preparing rare earth-doped antibacterial nanoceramic films, comprising the following steps:

[0047] S1: Preparation of rare earth antibacterial agent: 15.0 g (0.035 mol) Ce(NO3)3·6H2O, 8.7 g (0.018 mol) La(NO3)3·6H2O, and 200 mL of deionized water were placed in a beaker and stirred until completely dissolved to obtain a mixed solution; 6.6 g (0.11 mol) urea was added and stirred for 10 min until the urea was completely dissolved to obtain a reaction solution; the reaction solution was transferred to the lining of a hydrothermal reactor (80% filling), the reactor lid was tightened, and the reactor was placed in an oven and reacted at 185 °C for 8.5 h. After the reaction was completed, the oven was closed, and the reactor was allowed to cool to room temperature. The liner was removed, and the solution was poured into centrifuge tubes and centrifuged at 8000 r / min for 15 min to obtain rare earth hydroxide precipitate. The rare earth hydroxide precipitate was washed three times with deionized water (100 mL of deionized water was added each time, and centrifuged to separate the precipitate). The precipitate was then placed in a forced-air drying oven and dried at 80℃ for 4 h. The dried precipitate was placed in a muffle furnace, heated to 610℃, and kept at that temperature for 3.2 h. After natural cooling, the rare earth antibacterial agent was obtained, and the particle size was measured to be 33 nm by a laser particle size analyzer.

[0048] S2: Substrate preparation: 60g Al2O3 powder, 4.8g PVA, 1.8g glycerol, and 29g deionized water were placed in a planetary ball mill and milled at 300r / min for 2h to prepare a ceramic slurry; the ceramic slurry was poured into the material tank of a casting machine, the coating thickness was set to 0.25mm, the PET base film running speed was 10cm / min, and it was dried at 60℃ for 2h to obtain a ceramic green body;

[0049] The green body was peeled off from the PET base film, placed in a muffle furnace, heated to 1210℃, held for 2.2h, and cooled to room temperature after sintering to obtain an Al2O3 ceramic substrate (diameter 120mm, thickness 0.2mm, porosity 31%, average pore size 2.8μm).

[0050] S3: Membrane coating: Place 73.5g ZrO2 powder, 1g rare earth antibacterial agent, 0.5g PEG-400 and 25g deionized water into a beaker and disperse it for 30 minutes using an ultrasonic disperser (300W) to prepare a membrane slurry;

[0051] An Al2O3 ceramic substrate was vertically immersed in the film slurry and held for 10 seconds. It was then pulled out at a speed of 5.5 cm / min and dried at 80 °C for 1 hour. The dried substrate was then placed in a muffle furnace, heated to 1010 °C, held for 1.6 hours, and cooled to obtain a rare earth antibacterial nano-ceramic film (film thickness 5.8 μm, average pore size 62 nm).

[0052] Example 3: A method for preparing rare earth-doped antibacterial nanoceramic films, comprising the following steps:

[0053] S1: Preparation of rare earth antibacterial agent: 19.5g (0.045mol) Ce(NO3)3·6H2O, 10.7g (0.022mol) La(NO3)3·6H2O, and 200mL deionized water were placed in a beaker and stirred until completely dissolved to obtain a mixed solution; 7.8g (0.13mol) urea was added and stirred for 10min until the urea was completely dissolved to obtain a reaction solution; the reaction solution was transferred to the lining of a hydrothermal reactor (80% filling), the reactor lid was tightened, and the reactor was placed in an oven and reacted at 195℃ for 9.5h; after the reaction was completed, the oven was closed, and the reactor was allowed to cool to room temperature. The lining was removed, the solution was poured into centrifuge tubes, and centrifuged at 8000r / min. Centrifuge for 15 min to obtain rare earth hydroxide precipitate; wash the rare earth hydroxide precipitate three times with deionized water (add 100 mL of deionized water each time and centrifuge to separate), then put the precipitate into a forced-air drying oven and dry at 80℃ for 4 h; put the dried precipitate into a muffle furnace, heat to 640℃, keep at the temperature for 3.8 h, and after natural cooling, obtain rare earth antibacterial agent with a particle size of 37 nm as measured by a laser particle size analyzer.

[0054] S2: Substrate preparation: 70g α-Al2O3 powder, 5.2g PVA, 2.2g glycerol, and 31g deionized water were placed in a planetary ball mill and milled at 300r / min for 2h to prepare a ceramic slurry; the ceramic slurry was poured into the material tank of a casting machine, the coating thickness was set to 0.25mm, the PET base film running speed was 10cm / min, and it was dried at 60℃ for 2h to obtain a ceramic green body;

[0055] The green body was peeled off from the PET base film, placed in a muffle furnace, heated to 1240℃, held for 2.8h, and cooled to room temperature after sintering to obtain an Al2O3 ceramic substrate (diameter 120mm, thickness 0.2mm, porosity 34%, average pore size 3.2μm).

[0056] S3: Membrane coating: Put 72g ZrO2 powder, 2g rare earth antibacterial agent, 1g PEG-400 and 25g deionized water into a beaker and disperse them for 30 minutes using an ultrasonic disperser (300W) to prepare a membrane slurry;

[0057] An Al2O3 ceramic substrate was vertically immersed in the film slurry, held for 10 seconds, and then pulled out at a speed of 7 cm / min. The substrate was then dried at 80°C for 1 hour. The dried substrate was placed in a muffle furnace, heated to 1040°C, held for 1.9 hours, and then cooled to obtain a rare earth antibacterial nano-ceramic film (film thickness 6.2 μm, average pore size 68 nm).

[0058] Example 4: Setting up a water treatment system:

[0059] A1: Constructing a rare earth antibacterial nano-ceramic membrane module: The rare earth antibacterial nano-ceramic membrane prepared in Example 1 was cut into circular membrane sheets with a diameter of 100 mm. A "flat plate" module structure was adopted, with each module containing 3 membrane sheets. The membrane sheets were separated by a silicone mesh (1 mm thick, 1 mm mesh pore size) to form a water flow channel. The module shell was made of food-grade ABS material and was equipped with an inlet, a concentrate outlet, and a product outlet. The inlet was located on one side of the module, and the concentrate outlet and product outlet were located on the other side to achieve "cross-flow filtration" (concentrate recirculation ratio 3:1).

[0060] A2: System Setup: Includes a pretreatment unit, a fine filtration unit, and a post-antibacterial unit;

[0061] A21: Pretreatment unit: composed of PP cotton (5μm) and activated carbon filter;

[0062] A22: Fine filtration unit: connected to rare earth antibacterial nano-ceramic membrane module, operating pressure 0.1-0.15MPa, water temperature 25℃, water production flow 120-150L / (m²・h);

[0063] A23: Rear antibacterial unit: filled with silver ion antibacterial particles.

[0064] Example 5 is the same as Example 4, except that the rare earth antibacterial nano-ceramic membrane prepared in Example 1 is replaced with the rare earth antibacterial nano-ceramic membrane prepared in Example 2.

[0065] Example 6 is the same as Example 4, except that the rare earth antibacterial nano-ceramic membrane prepared in Example 1 is replaced with the rare earth antibacterial nano-ceramic membrane prepared in Example 3.

[0066] Performance testing

[0067] (1) Antibacterial performance test

[0068] According to the "Test Method for Antibacterial Properties of Antibacterial Ceramic Products" (JC / T 897-2014), bacterial suspensions of Escherichia coli (ATCC25922), Staphylococcus aureus (ATCC25923), and Pseudomonas aeruginosa (ATCC27853) (concentration 10) were tested. 6 CFU / mL was added dropwise to the surface of the rare earth antibacterial nanoceramic membranes prepared in Examples 1-3 (0.1 mL per membrane), and the membranes were incubated at 37°C for 24 h. The number of surviving colonies was counted, and the antibacterial rate was calculated. The results are shown in Table 1.

[0069] Table 1: Statistical Table of Antibacterial Performance Test Data for Examples 1-3

[0070]

[0071] As shown in Table 1, the rare earth antibacterial nanoceramic membrane prepared in this application has a high antibacterial rate against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa; and the antibacterial performance does not require external stimulation and has high safety.

[0072] (2) Mechanical property testing

[0073] According to the "Test Method for Tensile Strength of Fine Ceramics" (GB / T 30766-2014), the rare earth antibacterial nano-ceramic films prepared in Examples 1-3 were cut into 10mm×50mm specimens and subjected to tensile testing using an electronic universal testing machine at a tensile speed of 1mm / min. The fracture strength was recorded. The test results are shown in Table 2.

[0074] (3) Filtration performance test

[0075] The pure water flux of the rare earth antibacterial nanoceramic membranes prepared in Examples 1-3 was measured using a membrane flux analyzer at a pressure of 0.1 MPa and a water temperature of 25°C. Simulated raw water with a turbidity of 5 NTU (containing 10 μg / mL of E. coli) was used. 4 The filtration test was conducted using CFU / mL to detect the turbidity and total bacterial count of the effluent; the test results are shown in Table 2.

[0076] Table 2: Statistical table of test data on mechanical and filtration performance of Examples 1-3

[0077]

[0078] As shown in Table 2, the rare earth antibacterial nano-ceramic membrane prepared in this application has a tensile strength ≥32MPa and a uniform pore size distribution (average pore size 50-80nm), which far exceeds the long-term water flow pressure (0.1-0.15MPa) of existing antibacterial ceramic membranes (<20MPa). Furthermore, the water flux is ≥150L / (m²・h・0.1MPa), the effluent turbidity is <0.1NTU, and the total bacterial count is <1CFU / mL, which meets the water quality requirements for direct drinking water.

[0079] (4) Long-term performance testing

[0080] Simulated raw water continuous filtration membrane module (product water flux 120L / (m) 2 • h)), After filtering a cumulative 1000L, the antibacterial rate and water flux of the membrane were tested; the membrane surface was swept back by compressed air for 5 minutes; it was then cleaned with 0.5% citric acid solution and rinsed with deionized water until neutral; the flux recovery rate after cleaning was tested; the test results are shown in Table 3;

[0081] Table 3: Statistical table of test data on mechanical and filtration performance of Examples 1-3

[0082]

[0083] As shown in Table 3, the rare earth antibacterial nano-ceramic membrane prepared in this application still has an antibacterial rate of ≥98% after a 1000L water flux test, thus solving the problem of biological pollution of traditional ceramic membranes.

[0084] The rare earth antibacterial nano-ceramic membrane was cleaned using a combination of physical cleaning and chemical cleaning, and the membrane flux recovery rate after cleaning was ≥95%.

[0085] (5) The water treatment system built in Examples 4-6 has a treatment capacity of 50L / h. The system was run continuously for 3 months. The water quality (turbidity, total number of bacteria, virus removal rate) and water flux of the membrane module were tested. The membrane surface was back-blown with compressed air for 5 minutes. The membrane was cleaned with 0.5% citric acid solution and then rinsed with deionized water until neutral. The water flux after cleaning was tested. The test results are shown in Table 4.

[0086] Table 4: Statistical Table of Test Data for Water Treatment Systems in Examples 4-6

[0087]

[0088] As shown in Table 4, the water treatment system constructed in this application consistently exhibits an effluent turbidity <0.1 NTU, a total bacterial count <1 CFU / mL, and a poliovirus removal rate ≥99.9%, meeting the CJ94-2020 standard; the water flux of the membrane module increased from an initial 120 L / (m³) 2 •h) decreased to 85L / (m 2 •h) (3 months later), after cleaning, it recovered to 115L / (m 2 •h), runs stably.

[0089] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A rare earth-doped antibacterial nanoceramic membrane, characterized in that, The antibacterial nano-ceramic membrane includes an Al2O3 ceramic substrate and a membrane layer attached to the surface of the Al2O3 ceramic substrate. The film layer is prepared by coating the surface of an Al2O3 ceramic substrate with a film layer slurry and then sintering it; the specific sintering steps are: sintering at 1200-1250℃ for 2-3 hours. The membrane slurry comprises ZrO2 powder and a rare earth antibacterial agent, wherein the rare earth antibacterial agent is a CeO2-La2O3 composite oxide. The preparation method of the rare earth antibacterial agent includes the following steps: dissolving Ce(NO3)3˙6H2O and La(NO3)3˙6H2O in deionized water, adding urea, performing a hydrothermal reaction, centrifuging, taking the precipitate, washing, drying, and calcining to obtain the rare earth antibacterial agent; the hydrothermal reaction is carried out at 180-200℃ for 8-10 hours; the calcination is carried out at 600-650℃ for 3-4 hours; The preparation method of the Al2O3 ceramic substrate includes the following steps: mixing α-Al2O3 powder, PVA, glycerol and deionized water to form a slurry, casting it into shape, drying it and sintering it to obtain the Al2O3 ceramic substrate; The method for preparing the rare earth-doped antibacterial nano-ceramic membrane includes the following steps: immersing an Al2O3 ceramic substrate in a membrane slurry and then sintering it to obtain a rare earth-doped antibacterial nano-ceramic membrane. The membrane slurry is prepared by mixing ZrO2 powder, rare earth antibacterial agent, PEG-400 and deionized water; The ZrO2 powder accounts for 60-75% of the total mass of the membrane slurry; the rare earth antibacterial agent accounts for 0.5-2% of the total mass of the membrane slurry; and the PEG-400 accounts for 0.3-1% of the total mass of the membrane slurry. The specific steps for sintering after impregnation treatment are as follows: immerse the Al2O3 ceramic substrate in the film slurry, remove it at a pulling speed of 5-8 cm / min, dry it, and sinter it at 1000-1050℃ for 1.5-2 hours.

2. The rare earth-doped antibacterial nanoceramic membrane according to claim 1, characterized in that, The Al2O3 ceramic substrate has a porosity of 30-35% and an average pore size of 2-5 μm; The thickness of the film is 5-8 μm, and the average pore size is 50-80 nm.

3. The rare earth-doped antibacterial nanoceramic membrane according to claim 1, characterized in that, The mass ratio of α-Al2O3 powder, PVA, glycerol, and deionized water is 60-70:4-6:1-3:25-35.

4. The rare earth-doped antibacterial nanoceramic membrane according to claim 1, characterized in that, The molar ratio of Ce(NO3)3˙6H2O, La(NO3)3˙6H2O, and urea is 1.5-2.5:0.8-1.2:5-7.

5. The antibacterial nano-ceramic membrane as described in any one of claims 1-4 is applied to a water treatment equipment or water treatment system.

6. The application as described in claim 5, characterized in that, The water treatment system includes a pretreatment unit, a fine filtration unit, and a post-antibacterial unit that are connected in sequence. The pretreatment unit consists of PP cotton and activated carbon filter element; The fine filtration unit is equipped with an antibacterial nano-ceramic membrane assembly; the antibacterial nano-ceramic membrane assembly is composed of antibacterial nano-ceramic membranes and silicone meshes spaced apart; each antibacterial nano-ceramic membrane assembly contains 3-5 antibacterial nano-ceramic membranes. The post-antibacterial unit is filled with silver ion antibacterial particles.

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