A method for preparing a ceramic-based Co single-atom catalytic membrane and its application

Abstract

This invention relates to a method for preparing a ceramic-based Co single-atom catalytic membrane and its application, belonging to the field of ceramic-based single-atom catalytic membrane preparation technology. The method involves pretreating and modifying an inorganic ceramic membrane to introduce amino groups, followed by impregnation and sintering to load tetradentate chelated Co ligands onto the ceramic membrane to prepare a Co-SA@CM catalytic membrane. This Co-SA@CM catalytic membrane exhibits excellent degradation ability for various antibiotics in water and maintains good anti-interference ability under various anion / cation or different pH conditions. Furthermore, the negligible Co leaching rate indicates that the membrane has excellent stability. The Co-SA@CM membrane prepared by this method possesses excellent stability and catalytic activity, solving the problems of poor stability and weak binding force of commonly used organic catalytic membranes.

Description

Technical Field

[0001] This invention belongs to the field of catalytic membrane preparation technology, and relates to a method for preparing ceramic-based Co single-atom catalytic membranes and their application in retaining and degrading antibiotics in water. Background Technology

[0002] Traditional membrane separation technologies (such as nanofiltration and reverse osmosis) only concentrate pollutants on the intercept side during the treatment of antibiotic wastewater, making it difficult to achieve deep removal. Coupled with catalytic processes, membrane separation technology can be used to efficiently treat antibiotic wastewater, achieving both separation and degradation. This is of great significance. Constructing a single-atom catalytic membrane reactor by immobilizing the active components on the surface or inside the separation membrane is a highly attractive technical approach. Most single-atom catalytic membranes are typically prepared by filtration of single-atom catalysts on organic polymer substrates, often facing problems such as poor catalyst-substrate bonding, easy catalyst aggregation, and easy catalyst loss [Yang Y, Li H, Fu W, et al. Large-scale deployment of single-atom catalysts via cross-scale confinement in ceramic membranes for advanced water treatment[J]. Nature Water, 2025, 3(11): 1281~1290]. Furthermore, the lack of sufficient mechanical robustness and chemical elasticity in organic polymer substrates makes it difficult for such catalytic membranes to operate long-term under harsh environments.

[0003] In contrast, ceramic membranes, due to their excellent chemical stability, mechanical strength, and corrosion resistance, have become a highly promising single-atom catalytic integration platform. Taylor Hedtke et al. [Hedtke T, Zhang Y, Beebe M, et al. Copper Single-Atom Catalyst on Nanoconfined Ceramic Membranes for Fenton-Like Removal of Organic Contaminants[J]. ACS ES&T Engineering, 2025, 5(5): 1171~1179] successfully prepared atomically dispersed copper single-atom catalysts on the inner wall of anodic alumina ceramic membrane pores using a method combining Cu-EDTA precursor electrostatic adsorption and high-temperature calcination. This catalytic membrane achieved a dead-end filtration removal rate of 54% for benzoic acid at pH = 4 and exhibited excellent stability within the pH = 4-8 range. The mechanism of action is that copper single-atom sites anchored in the membrane pores activate H2O2 to generate ·OH free radicals. At the same time, the nano-confinence effect of the membrane pores significantly shortens the diffusion distance between free radicals and pollutants and improves the reaction kinetics.

[0004] This synergistic "filtration-catalytic oxidation" design holds promise for achieving high-throughput, continuous, and low-Co leaching efficient water purification. However, research on single-atom ceramic catalytic membrane catalytic oxidation processes is relatively scarce, and the catalytic activity and stability of ceramic membranes need further improvement. Therefore, developing a Co single-atom catalytic membrane based on ceramic membranes that combines high catalytic activity and stability to address the problems of insufficient catalytic activity and poor stability of existing membranes is of great significance for promoting the industrial application of ceramic-based single-atom catalytic membrane technology for antibiotic degradation. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a catalytic membrane by introducing Co single atoms on a ceramic substrate and its application in treating antibiotics in water. This method solves the problems of poor adhesion, easy catalyst loss, and poor mechanical robustness of catalytic membranes obtained by filtration of catalysts on organic substrates. At the same time, the Co-SA@CM membrane has excellent degradation effect on emerging pollutants in water.

[0006] The technical solution of this invention: a method for preparing a ceramic-based Co single-atom catalytic membrane, comprising the following steps:

[0007] 1) Pretreatment of ceramic hollow fiber membrane: First, seal one end of the inorganic ceramic hollow fiber membrane, and uniformly coat the outer surface of the inorganic ceramic hollow fiber substrate with 8-15 wt% zirconium oxide sol using the dip-coating process; after dip-coating, dry and calcine to obtain the pretreated ceramic hollow fiber membrane.

[0008] 2) Modification of ceramic hollow fiber membrane: The pretreated ceramic hollow fiber membrane is vertically immersed in a 3-aminopropyltriethoxysilane (APTES) solution with a mass fraction of 8-15%, reacted in an oven at 60-80°C, rinsed with ethanol, and vacuum dried to obtain the modified ceramic hollow fiber membrane.

[0009] 3) Preparation of precursor solution: Co(NO3)2·6H2O and 1,4,8,11-tetraazacyclotetradecane were added to methanol solution in a molar ratio of 1:3 and stirred at room temperature to obtain precursor solution;

[0010] 4) Loading Co single atoms onto the successfully modified ceramic hollow fiber membrane: The modified ceramic hollow fiber membrane is immersed in the precursor solution for 5-20 min; dried and calcined to prepare the ceramic-based Co single-atom catalytic membrane Co-SA@CM.

[0011] Further, in step 1), the impregnation time is controlled to be 1-5 min to obtain the impregnated carrier; the impregnated carrier is placed in a vacuum oven to dry, and then calcined in a muffle furnace with an air sintering atmosphere at a temperature of 300°C-500°C for 180-300 min.

[0012] Furthermore, in step 4), the impregnated ceramic hollow fiber membrane is placed in a vacuum oven for drying and then calcined in a tube furnace with an argon sintering atmosphere at 800°C-1000°C for 2-5 hours.

[0013] A method for preparing a ceramic-based Co single-atom catalytic membrane, the specific steps of which are as follows:

[0014] 1) Pretreatment of ceramic hollow fiber membrane: First, one end of the inorganic ceramic hollow fiber membrane is sealed with raw material tape. Then, 10 wt% zirconium oxide sol is uniformly coated on the outer surface of the inorganic ceramic hollow fiber substrate using an impregnation and lifting process. During the above process, the impregnation time is controlled to be 1 min to obtain a successfully impregnated carrier. The carrier is then placed in a vacuum oven to dry for 24 h and calcined in a muffle furnace with an air sintering atmosphere at 400°C for 240 min to improve the pore size of the ceramic hollow fiber membrane.

[0015] 2) Modification of ceramic hollow fiber membrane: First, a 10% solution of 3-aminopropyltriethoxysilane (APTES) was prepared and vertically immersed in the solution. The membrane was then reacted in an oven at 70°C for 2 h. After rinsing with ethanol, the membrane was vacuum dried overnight at 60°C, and -NH2 was successfully grafted onto the ceramic hollow fiber substrate.

[0016] 3) Preparation of precursor solution: 1,4,8,11-tetraazacyclotetradecane (Cyclam) was used as the ligand for metallic Co; Co(NO3)2·6H2O and Cyclam were added to methanol solution in a molar ratio of 1:3 and stirred at room temperature to obtain precursor solution;

[0017] 4) Loading Co single atoms onto the successfully modified ceramic hollow fiber membrane: The modified ceramic hollow fiber membrane from step 2) was impregnated in the precursor solution from step 3) using an dip-coating process; the impregnation time was controlled to be 10 min during the above process. Afterwards, it was placed in a vacuum oven at 60°C for overnight drying, and then calcined in a tube furnace under an argon atmosphere at 900°C for 3 h to prepare the ceramic-based Co single-atom catalytic membrane Co-SA@CM.

[0018] A ceramic-based Co single-atom catalytic membrane, Co-SA@CM, was used to activate PMS to degrade antibiotics in water.

[0019] The application of the ceramic-based Co single-atom catalytic membrane Co-SA@CM is described in the application of activating the Co-SA@CM catalytic membrane in the degradation of antibiotics by PMS under gravity.

[0020] Furthermore, the gravity-driven height difference is 25cm.

[0021] Furthermore, the contaminants include tetracycline, sulfadiazine, moxifloxacin, sulfamethoxazole, etc.

[0022] Furthermore, the Co-SA@CM / PMS system exhibited excellent removal performance for tetracycline, sulfadiazine, and moxifloxacin, achieving a degradation rate of nearly 100% within 20 minutes. It also showed good degradation of sulfamethoxazole, reaching nearly 80% within 20 minutes.

[0023] The beneficial effects of this invention are as follows: 1. A Co single-atom catalytic membrane was prepared by introducing Co single atoms onto a ceramic substrate, which is a simple process. Under the action of tetradentate chelate coordination effect, the Co single atoms are firmly stabilized in the ceramic membrane framework, effectively overcoming the problem of easy migration and aggregation of single-atom materials under harsh reaction conditions. 2. The membrane pores in the catalytic membrane form a synergistic effect of "filtration-catalytic oxidation" with PMS. The Co single-atom sites anchored on the membrane activate PMS to generate a series of reactive oxygen species. At the same time, the nano-confinement effect of the membrane pores significantly shortens the diffusion distance between reactive oxygen species and pollutants and improves the reaction kinetics. Moreover, the Co-SA@CM / PMS system shows excellent removal performance for a variety of antibiotics. 3. It has excellent stability. Under the conditions of pH 3, 5, 9, and 11, Co-SA@CM can still maintain good degradation performance, meeting the needs of practical applications. 4. The average leaching amount of Co ions detected in the effluent is only 0.003 mg / L. -1 It is far below the limit for Co in drinking water and surface water stipulated by Chinese national standards (0.01 mg / L). -1 ) Attached Figure Description

[0024] Figure 1 These are physical images, SEM images, and EDS mapping images of the Co-SA@CM membrane. Among them, (a) is a physical image of Co-SA@CM, (bc) is a cross-sectional SEM image of Co-SA@CM, (d) is a SEM image of the outer surface of Co-SA@CM, and (ej) is an EDS mapping image of the outer surface of Co-SA@CM.

[0025] Figure 2 This is the XRD pattern of Co-SA@CM;

[0026] Figure 3 It is the XANES graph of the Co-SA@CM with K edges;

[0027] Figure 4 It is the FT K-2 weighted EXAFS spectrum of Co-SA@CM;

[0028] Figure 5 These are the K-edge WT-EXAFS diagrams of Co-SA@CM, where (a) is the WT diagram of Co foil, (b) is the WT diagram of Co3O4, (c) is the WT diagram of CoO, (d) is the WT diagram of CoPc, and (e) is the WT diagram of Co-SA@CM.

[0029] Figure 6 Here are the performance test graphs of the Co-SA@CM membrane: (a) the effect of initial TC concentration and (b) initial pH conditions on the degradation of TC in the Co-SA@CM / PMS system.

[0030] Figure 7 The anti-interference ability test data of Co-SA@CM membrane are as follows: (a) the effect of different anions and cations on the degradation of TC by the Co-SA@CM / PMS system; (b) the degradation effect of the Co-SA@CM / PMS system on different antibiotics. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below with reference to the technical solutions and accompanying drawings.

[0032] Example 1: Alumina ceramic-based Co single-atom catalytic membrane: Preparation of Co-based catalytic ceramic membrane

[0033] 1) Pretreatment of zirconia ceramic hollow fiber membrane: First, one end of the Al2O3 ceramic hollow fiber membrane is sealed with raw material tape. Then, 10 wt% zirconia sol is uniformly coated on the outer surface of the Al2O3 ceramic hollow fiber substrate using an impregnation and pulling process. During the above process, the impregnation time is controlled to be 1 min to obtain a successfully impregnated carrier. Then, the carrier is placed in a vacuum oven to dry for 24 h and calcined in a muffle furnace with an air sintering atmosphere at 400°C for 240 min to obtain the pretreated ceramic membrane.

[0034] 2) Modification of Al2O3 ceramic hollow fiber membrane: It was immersed in a 10 wt% solution of 3-aminopropyltriethoxysilane (APTES) and reacted at 70°C for 2 h for modification. Then it was rinsed with ethanol and vacuum dried at 60°C overnight for later use.

[0035] 3) Preparation of precursor solution: 1,4,8,11-tetraazacyclotetradecane (Cyclam) was used as the ligand for metal Co; Co(NO3)2·6H2O and Cyclam were added to methanol solution in a certain molar ratio and stirred at room temperature to obtain precursor solution.

[0036] 4) Preparation of catalytic ceramic membrane: The membrane was immersed in the precursor solution for 10 min, vertically pulled out, and placed in a vacuum oven for overnight vacuum drying at 60°C. It was then calcined at 900°C for 3 h in a tube furnace under an argon sintering atmosphere to prepare the Co-based catalytic ceramic membrane.

[0037] Example 2: Preparation of Zirconia Ceramic-Based Co Single-Atom Catalytic Membrane Co-SA@CM

[0038] 1) Pretreatment of zirconia ceramic hollow fiber membrane: First, one end of the ZrO2 ceramic hollow fiber membrane is sealed with raw material tape. Then, 10 wt% zirconia sol is uniformly coated on the outer surface of the ZrO2 ceramic hollow fiber substrate using an impregnation and pulling process. During the above process, the impregnation time is controlled to be 1 min to obtain a successfully impregnated carrier. The carrier is then placed in a vacuum oven to dry for 24 h and calcined in a muffle furnace with an air sintering atmosphere at 400°C for 240 min to obtain the pretreated ceramic membrane.

[0039] 2) Modification of zirconia ceramic hollow fiber membrane: It was immersed in a 10 wt% solution of 3-aminopropyltriethoxysilane (APTES) and reacted at 70°C for 2 h for modification. Then it was rinsed with ethanol and vacuum dried at 60°C overnight for later use.

[0040] 3) Preparation of precursor solution: 1,4,8,11-tetraazacyclotetradecane (Cyclam) was used as the ligand for metal Co; Co(NO3)2·6H2O and Cyclam were added to methanol solution in a certain molar ratio and stirred at room temperature to obtain precursor solution.

[0041] 4) Preparation of Co-SA@CM catalytic ceramic membrane: The membrane was immersed in the precursor solution for 10 min, vertically pulled out, and placed in a vacuum oven for overnight vacuum drying at 60°C. The membrane was then calcined at 900°C for 3 h in a tube furnace under an argon sintering atmosphere to obtain the Co-SA@CM catalytic ceramic membrane. Figure 1 The image shown in section a features a photograph of the actual Co-SA@CM. Figure 1 In the images b and c, respectively, are the overall cross-sectional SEM and the magnified local SEM images of Co-SA@CM, which clearly show its cross-sectional structural features. Figure 1 The surface SEM image of Co-SA@CM shows the surface microstructure, and the corresponding EDS mapping indicates the successful modification of the film and the loading of Co. Figure 1 The XRD pattern of the catalytic membrane matches the peak shape of the base membrane. Furthermore, comparing with the Co standard card (JCPDS 15-0806), the characteristic peaks of metallic Co typically appear around 44° (111 crystal plane), 51.5° (200 crystal plane), and 76° (220 crystal plane). No diffraction peaks attributable to elemental cobalt were observed in the prepared Co-SA@CM, indicating that the Co element on the catalytic membrane is supported on the ZrO2 ceramic membrane in the form of single atoms. Figure 2 The k-edge XANES spectrum of Co-SA@CM shows that the near-edge absorption energy is between CoPc and CoO, indicating that the Co atoms in Co-SA@CM are positively charged and exist in a +2 valence state. Figure 3Further insights were gained through Fourier transform extended X-ray absorption fine structure (EXAFS) analysis. Figure 4 These results highlight the importance of 2.2. The absence of obvious peaks corresponding to Co-Co bonds at the left and right positions confirms that Co is dispersed in single-atom form on the film material, indicating the absence of Co nanoparticles in the prepared material. This is consistent with the XRD results, and this separation supports the assertion of single-atom coordination. Co-SA@CM at approximately 1.5 There is a main peak at this location, which coincides with the peak of CoPc, and is attributed to Co-N coordination. From Figure 5 The wavelet transform diagram shows that the Co-SA@CM catalytic film at approximately 1.5 The highest fluorescence intensity was observed at this location, significantly close to the Co-N peak in CoPc, and clearly distinct from that of Co foil (approximately 2.2). ) and CoO (approximately 1.6 The main peak position of the film is shown. Based on the above analysis, it is evident that a Co-monetized N-doped ceramic-based catalytic film anchored to a single atom has been successfully prepared.

[0042] Example 3: Performance testing of Co-SA@CM catalytic membrane

[0043] A gravity-driven cross-flow testing device was used, with the feed solution being a mixed aqueous solution containing 10 ppm tetracycline (TC) and 2 mM PMS. After collecting the sample from the permeate side, an appropriate amount of sodium thiosulfate solution was immediately added to quench residual reactive oxygen species, thereby terminating the catalytic reaction. Finally, the absorbance of the treated sample was measured using a UV-Vis spectrophotometer to determine the remaining TC concentration and evaluate the degradation performance of the catalytic membrane. Figure 6 In the figure, 'a' represents different initial concentrations (5, 10, 15, 20, 30 mg L). -1 The degradation performance of the Co-SA@CM / PMS system was evaluated, with the system exhibiting degradation rates in the range of 5-30 mg / L. -1 It can achieve efficient and stable degradation within the TC concentration range. Figure 6 Figure b shows the degradation performance of the Co-SA@CM / PMS system for TC in different pH ranges (pH=3, 5, 9, 11). Under near-neutral and alkaline conditions (pH = 5.0-11.0), Co-SA@CM exhibits stable and excellent catalytic performance, with no significant decrease in TC removal efficiency. This indicates that the catalytic system can effectively activate PMS and degrade pollutants in various acidic and alkaline environments. This wide pH applicable range demonstrates that the Co-SA@CM / PMS system has good environmental adaptability and operational flexibility in practical water treatment applications, and is particularly suitable for complex water quality conditions with large pH fluctuations.

[0044] Example 4: Stability test of Co-SA@CM catalytic membrane

[0045] To further investigate the influence of complex ions in actual water bodies on the catalytic oxidation process, a variety of common inorganic anions (NO3-) were systematically examined. - SO4 2- CO3 2- ) and cations (K) + Na + The interference effect of coexistence on the degradation of TC in the Co-SA@CM / PMS system. For example... Figure 7 As shown in Figure a, when NO3- concentration of 2 mM is present in the reaction system... - SO4 2- or K + At that time, the removal rate of TC remained close to 100% within 20 minutes, and the degradation kinetics were not significantly inhibited. To further verify the substrate universality and practical application potential of this system, three typical antibiotic pollutants, SMX, SMT, and MFX, were selected as target compounds for degradation evaluation. Figure 7 As shown in Figure b, under the same reaction conditions, the Co-SA@CM / PMS system exhibits excellent removal performance for all the above pollutants, demonstrating a certain degree of universality. ICP testing revealed that the membrane has a negligible Co leaching rate (0.003 mg / L). -1 The concentration of CO in drinking water and surface water is far below the national standard limit (0.01 mg / L). -1 ).

[0046] 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 ceramic-based Co single-atom catalytic membrane, characterized in that, The steps are as follows: 1) Pretreatment of ceramic hollow fiber membrane: First, seal one end of the inorganic ceramic hollow fiber membrane, and then uniformly coat the outer surface of the inorganic ceramic hollow fiber substrate with 8-15 wt% zirconium oxide sol using the dip-coating process. After impregnation, the membrane is dried and calcined to obtain a pretreated ceramic hollow fiber membrane. 2) Modification of ceramic hollow fiber membrane: The pretreated ceramic hollow fiber membrane is vertically immersed in a 3-aminopropyltriethoxysilane solution with a mass concentration of 8-15%, reacted in an oven at 60-80°C, rinsed with ethanol, and vacuum dried to obtain the modified ceramic hollow fiber membrane. 3) Preparation of precursor solution: Co(NO3)2·6H2O and 1,4,8,11-tetraazacyclotetradecane were added to methanol solution in a molar ratio of 1:3 and stirred at room temperature to obtain precursor solution; 4) Loading Co single atoms onto the successfully modified ceramic hollow fiber membrane: Immerse the modified ceramic hollow fiber membrane in the precursor solution for 5-20 min; The ceramic-based Co single-atom catalytic membrane Co-SA@CM was prepared by drying and calcination.

2. The method for preparing a ceramic-based Co single-atom catalytic membrane according to claim 1, characterized in that, In step 1), the impregnation time is controlled to be 1-5 min to obtain the impregnated carrier; the impregnated carrier is placed in a vacuum oven to dry, and then calcined in a muffle furnace with an air sintering atmosphere at a temperature of 300°C-500°C for 180-300 min.

3. The method for preparing a ceramic-based Co single-atom catalytic membrane according to claim 1, characterized in that, In step 4), the impregnated ceramic hollow fiber membrane is placed in a vacuum oven to dry and then calcined in a tube furnace with an argon sintering atmosphere at 800°C-1000°C for 2-5 hours.

4. A ceramic-based Co single-atom catalytic membrane, characterized in that: The ceramic-based Co single-atom catalytic membrane is prepared by the preparation method described in any one of claims 1-3.

5. An application of a ceramic-based Co single-atom catalytic membrane, characterized in that: The ceramic-based Co single-atom catalytic membrane is used to confine and retain antibiotics in water.

6. The application of the ceramic-based Co single-atom catalytic membrane according to claim 5, characterized in that: The antibiotics mentioned are sulfamethoxazole, sulfadiazine, tetracycline, and moxifloxacin.

7. An application of a ceramic-based Co single-atom catalytic membrane, characterized in that: The ceramic-based Co single-atom catalytic membrane is used to activate PMS to degrade antibiotics in water.

8. The application of the ceramic-based Co single-atom catalytic membrane according to claim 7, characterized in that, The ceramic-based Co single-atom catalytic membrane is used to activate PMS under gravity to degrade antibiotics in water.

9. The application of the ceramic-based Co single-atom catalytic membrane according to claim 8, characterized in that, The gravity-driven height difference is 20-30cm.

10. The application of a ceramic-based Co single-atom catalytic membrane according to any one of claims 7-9, characterized in that, The antibiotics mentioned are sulfamethoxazole, sulfadiazine, tetracycline, and moxifloxacin.

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