Carboxylated multi-walled carbon nanotube modified ceramic membrane, preparation method and application thereof

Abstract

The application discloses a carboxylated multi-walled carbon nanotube modified ceramic membrane and a preparation method and application thereof, wherein carboxylated multi-walled carbon nanotubes (MWCNTs) and copper ferrite nanomaterials (CuFe2O4) are modified on the ceramic membrane to endow the ceramic membrane with synchronous anti-pollution and catalytic degradation performance; the copper ferrite nanomaterials are coated on the surface of the ceramic membrane through impregnation, and after calcination, the carboxylated multi-walled carbon nanotube materials are deposited in situ, so that the prepared carboxylated multi-walled carbon nanotube modified ceramic membrane (MWCNTs@CuFe2O4) can simultaneously realize efficient oil-water separation and effective removal of organic pollutants, so as to achieve the effect of modifying the ceramic membrane to reduce membrane pollution and remove refractory substances in oily wastewater.

Description

Technical Field

[0001] This invention belongs to the field of ceramic membrane preparation technology, specifically relating to a carboxylated multi-walled carbon nanotube modified ceramic membrane, its preparation method, and its application. Background Technology

[0002] Industrial development has made life more convenient for human society, but it has also caused many environmental problems, among which water pollution is particularly prominent in many parts of the world. Oily wastewater has a complex composition, rich in insoluble oils and toxic organic pollutants. Its discharge can cause serious pollution to surface water, groundwater, and soil. Further bioaccumulation of toxic substances in wastewater will threaten human health. In the past few decades, membrane technology has been widely used in the treatment of drinking water and sewage. Ultrafiltration ceramic membrane technology has shown good application prospects in the treatment of emulsified oily wastewater due to its advantages such as high separation efficiency and stable physicochemical properties. However, ultrafiltration ceramic membrane technology faces two major challenges when used to treat oily wastewater: 1. The complex composition and properties of emulsified oil can easily lead to increased membrane fouling, resulting in accelerated membrane flux decline and affecting membrane separation performance; 2. Oily wastewater often contains toxic small organic molecules miscible with water, which are difficult to treat with membrane separation. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a carboxylated multi-walled carbon nanotube modified ceramic membrane, its preparation method and application. By modifying the ceramic membrane with carboxylated multi-walled carbon nanotubes (MWCNTs) and copper ferrite nanomaterials (CuFe2O4), it is endowed with simultaneous anti-pollution and catalytic degradation properties, so as to achieve the goal of efficient separation of oily wastewater and degradation of coexisting organic matter.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for preparing a carboxylated multi-walled carbon nanotube modified ceramic film, comprising the following steps:

[0005] S1: Prepare the solution;

[0006] S101: Preparation of impregnation mother liquor: Dissolve copper source and iron source in deionized water to obtain solution A. Heat complexing agent to 55-65℃, and then add solution A dropwise to complexing agent while stirring. After mixing, continue stirring at 55-65℃ for 1-2 hours. Finally, age at room temperature for 10-14 hours to obtain impregnation mother liquor.

[0007] S102: Preparation of carboxylated multi-walled carbon nanotubes (MWCNTs) solution: Dissolve carboxylated multi-walled carbon nanotubes (MWCNTs) in deionized water and sonicate to obtain a carboxylated multi-walled carbon nanotubes (MWCNTs) solution with a concentration of 0.02-0.05 mg / mL;

[0008] S2: Immersion coating: Immerse the ceramic membrane in the immersion mother liquor for 10-20 seconds, then rinse with deionized water for 3-5 minutes, and then dry the ceramic membrane at 60-80℃ for 1-2 hours. Repeat the immersion-rinse-drying steps 2-3 times to obtain the coated membrane.

[0009] S3: Calcination and phase formation: The coated film is calcined at 300-500℃ for 2-5 hours. The high temperature can form the phase of the copper ferrite catalyst and strengthen the bonding strength between the copper ferrite catalyst and the ceramic film. Then, it is naturally cooled to room temperature, rinsed with deionized water for 3-5 minutes, and then the coated film is dried at 75-85℃ for 2-4 hours to obtain the copper ferrite (CuFe2O4) modified film.

[0010] S4: In-situ deposition: The copper ferrite (CuFe2O4) modified membrane is loaded into a filtration device, and the carboxylated multi-walled carbon nanotube (MWCNTs) solution is filtered at 0.1-0.3 MPa until the UV254 value of the filtered water is 0, thus obtaining a carboxylated multi-walled carbon nanotube modified ceramic membrane (MWCNTs@CuFe2O4).

[0011] Based on the above technical solution, the present invention can be further improved as follows:

[0012] Furthermore, the copper source is copper nitrate, and the iron source is ferric nitrate.

[0013] Furthermore, the concentration of Cu in solution A is 0.15-0.25 mol / L, and the concentration of Fe is 0.35-0.45 mol / L.

[0014] Furthermore, the complexing agent is a citric acid solution with a concentration of 0.5-0.7 mol / L.

[0015] Furthermore, the time required to heat the complexing agent to the target temperature is 25-35 minutes.

[0016] Furthermore, in step S102, the ultrasonic power is 30-50W and the ultrasonic time is 20-40min.

[0017] Furthermore, the ceramic membrane is washed 2-3 times with deionized water before impregnation, and then dried at 60-80℃ for 15-25 minutes.

[0018] Furthermore, the calcination temperature is 400℃ and the calcination time is 3.5h.

[0019] The present invention also discloses a method for preparing a carboxylated multi-walled carbon nanotube modified ceramic membrane.

[0020] This invention also discloses the application of carboxylated multi-walled carbon nanotube modified ceramic membranes in wastewater treatment.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) To address the limitations of the single separation function of ceramic membranes and the problem of membrane fouling, a method of modifying ceramic membranes with carboxylated multi-walled carbon nanotubes by "modifying the surface properties of the membrane with hydrophilic materials and catalytically modifying and degrading pollutants with copper ferrite" is proposed. Through the efficient early selective separation of the hydrophilic layer on the membrane surface and the subsequent environmentally friendly SR-AOPs process in the membrane pores, efficient oil-water separation and effective removal of organic pollutants can be achieved simultaneously.

[0023] (2) Combining the membrane fouling mechanism and catalytic degradation mechanism in membrane fouling, this study reveals the synergistic mechanism of the coupling between the anti-oil droplet adsorption of the hydrophilic functional layer and the site degradation of organic matter in the catalytic functional layer, providing a solution for the further promotion and application of ceramic membrane technology in the field of emulsified oil wastewater treatment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process of the present invention;

[0025] Figure 2 Figure 1 shows the SEM images of the membrane surface. Figure 2 shows the original ceramic membrane (CM), Figure 3 shows the CuFe2O4 modified ceramic membrane (CuFeCM) prepared in the comparative example, and Figure 4 shows the MWCNTs@CuFe2O4 modified ceramic membrane (CCuFeCM) prepared in Example 1.

[0026] Figure 3 Figure 1 shows the SEM images of the membrane cross sections. Figure 2 shows the original ceramic membrane (CM), Figure 3 shows the CuFe2O4 modified ceramic membrane (CuFeCM) prepared in the comparative example, and Figure 4 shows the MWCNTs@CuFe2O4 modified ceramic membrane (CCuFeCM) prepared in Example 1.

[0027] Figure 4 The images shown are SEM-EDX images of the surface of the MWCNTs@CuFe2O4 modified ceramic film (CCuFeCM) prepared in Example 1. Figure (a) is the C element signal imaging image, Figure (b) is the Fe element signal imaging image, Figure (c) is the Cu element signal imaging image, and Figure (d) is the signal imaging image of the main constituent elements of CCuFeCM.

[0028] Figure 5 XPS spectra of the membrane;

[0029] Figure 6 The infrared spectrum of the membrane;

[0030] Figure 7 The image shows the XRD spectrum of the membrane.

[0031] Figure 8The water contact angle (top) and underwater oil contact angle (bottom) of the membrane;

[0032] Figure 9 The effect of adding a capture agent on the catalytic degradation effect of RhB;

[0033] Figure 10 EPR spectrum for DMPO capturing free radicals;

[0034] Figure 11 EPR spectrum for TEMP to capture free radicals;

[0035] Figure 12 Synergistic mechanism for treating RhB-containing emulsified oil wastewater. Detailed Implementation

[0036] The specific embodiments of the present invention are described below to facilitate understanding of the invention by those skilled in the art. Unless otherwise specified, specific conditions are applied according to conventional conditions or the manufacturer's recommendations. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims. All inventions utilizing the concept of this invention are protected.

[0037] Example 1:

[0038] A carboxylated multi-walled carbon nanotube modified ceramic film, the preparation method of which is as follows: Figure 1 As shown, it includes the following steps:

[0039] S1: Prepare the solution;

[0040] S101: Preparation of impregnation mother liquor: Weigh 2.416g (10mmol) copper nitrate and 8.08g (20mmol) ferric nitrate and dissolve them in deionized water to obtain 50mL solution A. Weigh 5.763g (30mmol) citric acid and dissolve it in deionized water to prepare 50mL solution. Heat the citric acid solution to 60℃ in 30min using a constant temperature magnetic stirrer. Then, while stirring, add solution A dropwise to the citric acid solution. After mixing, continue stirring at 60℃ for 1.5h. Finally, age at room temperature for 12h to obtain the impregnation mother liquor.

[0041] S102: Preparation of carboxylated multi-walled carbon nanotubes (MWCNTs) solution: Dissolve carboxylated multi-walled carbon nanotubes (MWCNTs) in 100 mL of deionized water, set the power of the ultrasonic machine to 40 W, and then sonicate for 30 min to obtain a carboxylated multi-walled carbon nanotubes (MWCNTs) solution with a concentration of 0.03 mg / mL.

[0042] S2: Impregnation Coating: Wash the ceramic membrane twice with deionized water to remove impurities from the membrane surface, then place it in an oven and dry it at 70°C for 20 minutes. After that, immerse the ceramic membrane in the impregnation mother liquor for 15 seconds, rinse it with deionized water for 4 minutes to remove excess impregnation mother liquor from the membrane surface, and then dry the ceramic membrane at 70°C for 1.5 hours. Repeat the impregnation-rinse-drying steps 3 times to obtain the coated membrane.

[0043] S3: Calcination and phase formation: The coated film was calcined at 400℃ for 3.5h, then removed and allowed to cool naturally to room temperature. It was then rinsed with deionized water for 4min, and then dried at 80℃ for 3h to obtain copper ferrite (CuFe2O4) modified film.

[0044] S4: In-situ deposition: The copper ferrite (CuFe2O4) modified membrane was rinsed with deionized water for 4 min, and then the copper ferrite (CuFe2O4) modified membrane was loaded into a filter device and the carboxylated multi-walled carbon nanotube (MWCNTs) solution was filtered at 0.2 MPa until the UV254 value of the filtered water was 0, thus obtaining a carboxylated multi-walled carbon nanotube modified ceramic membrane (MWCNTs@CuFe2O4).

[0045] Example 2:

[0046] A carboxylated multi-walled carbon nanotube modified ceramic film, the preparation method of which includes the following steps:

[0047] S1: Prepare the solution;

[0048] S101: Preparation of impregnation mother liquor: Weigh 1.812g (7.5mmol) copper nitrate and 9.09g (22.5mmol) ferric nitrate and dissolve them in deionized water to obtain 50mL solution A. Weigh 4.803g (25mmol) citric acid and dissolve it in deionized water to prepare 50mL solution. Heat the citric acid solution to 55℃ in 25min using a constant temperature magnetic stirrer. Then, while stirring, add solution A dropwise to the citric acid solution. After mixing, continue stirring at 65℃ for 1h. Finally, age at room temperature for 14h to obtain the impregnation mother liquor.

[0049] S102: Preparation of carboxylated multi-walled carbon nanotubes (MWCNTs) solution: Dissolve carboxylated multi-walled carbon nanotubes (MWCNTs) in 100 mL of deionized water, set the power of the ultrasonic machine to 30 W, and then sonicate for 40 min to obtain a carboxylated multi-walled carbon nanotubes (MWCNTs) solution with a concentration of 0.02 mg / mL.

[0050] S2: Impregnation Coating: Wash the ceramic membrane three times with deionized water to remove impurities from the membrane surface, then place it in an oven and dry it at 80°C for 15 minutes. After that, immerse the ceramic membrane in the impregnation mother liquor for 20 seconds, rinse it with deionized water for 3 minutes to remove excess impregnation mother liquor from the membrane surface, and then dry the ceramic membrane at 60°C for 2 hours. Repeat the impregnation-rinse-drying steps twice to obtain the coated membrane.

[0051] S3: Calcination and phase formation: The coated film was calcined at 300℃ for 5 hours, then removed and allowed to cool naturally to room temperature. It was then rinsed with deionized water for 3 minutes, and then dried at 75℃ for 4 hours to obtain a copper ferrite (CuFe2O4) modified film.

[0052] S4: In-situ deposition: The copper ferrite (CuFe2O4) modified membrane was rinsed with deionized water for 5 min, and then the copper ferrite (CuFe2O4) modified membrane was loaded into a filter device and the carboxylated multi-walled carbon nanotube (MWCNTs) solution was filtered at 0.1 MPa until the UV254 value of the filtered water was 0, thus obtaining a carboxylated multi-walled carbon nanotube modified ceramic membrane (MWCNTs@CuFe2O4).

[0053] Example 3:

[0054] A carboxylated multi-walled carbon nanotube modified ceramic film, the preparation method of which includes the following steps:

[0055] S1: Prepare the solution;

[0056] S101: Preparation of impregnation mother liquor: Weigh 3.02g (12.5mmol) copper nitrate and 7.07g (17.5mmol) ferric nitrate and dissolve them in deionized water to obtain 50mL solution A. Weigh 6.724g (35mmol) citric acid and dissolve it in deionized water to prepare 50mL solution. Heat the citric acid solution to 65℃ in 35min using a constant temperature magnetic stirrer. Then, while stirring, add solution A dropwise to the citric acid solution. After mixing, continue stirring at 55℃ for 2h. Finally, age at room temperature for 10h to obtain impregnation mother liquor.

[0057] S102: Preparation of carboxylated multi-walled carbon nanotubes (MWCNTs) solution: Dissolve carboxylated multi-walled carbon nanotubes (MWCNTs) in 100 mL of deionized water, set the power of the ultrasonic machine to 50 W, and then sonicate for 20 min to obtain a carboxylated multi-walled carbon nanotubes (MWCNTs) solution with a concentration of 0.05 mg / mL.

[0058] S2: Impregnation Coating: Wash the ceramic membrane twice with deionized water to remove impurities on the membrane surface, then place it in an oven and dry at 60°C for 25 minutes. Then, immerse the ceramic membrane in the impregnation mother liquor for 10 seconds, rinse with deionized water for 5 minutes to remove excess impregnation mother liquor from the membrane surface, and then dry the ceramic membrane at 80°C for 1 hour. Repeat the impregnation-rinse-drying steps 3 times to obtain the coated membrane.

[0059] S3: Calcination and phase formation: The coated film was calcined at 500℃ for 2 hours, then removed and allowed to cool naturally to room temperature. It was then rinsed with deionized water for 5 minutes, and then dried at 85℃ for 2 hours to obtain a copper ferrite (CuFe2O4) modified film.

[0060] S4: In-situ deposition: The copper ferrite (CuFe2O4) modified membrane was rinsed with deionized water for 3 min, and then the copper ferrite (CuFe2O4) modified membrane was loaded into a filter device and the carboxylated multi-walled carbon nanotube (MWCNTs) solution was filtered at 0.3 MPa until the UV254 value of the filtered water was 0, thus obtaining a carboxylated multi-walled carbon nanotube modified ceramic membrane (MWCNTs@CuFe2O4).

[0061] Comparative example:

[0062] A method for preparing a copper ferrite (CuFe2O4) modified ceramic membrane includes the following steps:

[0063] S1: Preparation of impregnation mother liquor: Weigh 2.416g (10mmol) copper nitrate and 8.08g (20mmol) ferric nitrate and dissolve them in deionized water to obtain 50mL solution A. Weigh 5.763g (30mmol) citric acid and dissolve it in deionized water to prepare 50mL solution. Heat the citric acid solution to 60℃ in 30min using a constant temperature magnetic stirrer. Then, while stirring, add solution A dropwise to the citric acid solution. After mixing, continue stirring at 60℃ for 1.5h. Finally, age at room temperature for 12h to obtain the impregnation mother liquor.

[0064] S2: Impregnation Coating: Wash the ceramic membrane twice with deionized water to remove impurities from the membrane surface, then place it in an oven and dry it at 70°C for 20 minutes. After that, immerse the ceramic membrane in the impregnation mother liquor for 15 seconds, rinse it with deionized water for 4 minutes to remove excess impregnation mother liquor from the membrane surface, and then dry the ceramic membrane at 70°C for 1.5 hours. Repeat the impregnation-rinse-drying steps 3 times to obtain the coated membrane.

[0065] S3: Calcination and phase formation: The coated film was calcined at 400℃ for 3.5h, then removed and allowed to cool naturally to room temperature. It was then rinsed with deionized water for 4min, and then dried at 80℃ for 3h to obtain copper ferrite (CuFe2O4) modified film.

[0066] Experimental example:

[0067] The MWCNTs@CuFe2O4 modified ceramic film (CCuFeCM) prepared in Example 1 and the CuFe2O4 modified ceramic film (CuFeCM) prepared in the comparative example were used as the experimental group, and the original ceramic film (CM) was used as the control group for the study.

[0068] 1. The apparent properties of the membrane were observed and analyzed using characterization techniques such as SEM / EDX, XPS, ATR-FTIR, XRD, and water contact angle. The results are as follows: Figure 2-8 As shown, Fe-O, Cu-O, and carboxyl functional groups were found on the surface of the CCuFeCM membrane. CuFe2O4 elements were distributed within the membrane pores, while MWCNTs elements were distributed on the surface, exhibiting a layered structure. The water contact angle decreased from 12.3° (CM) to 5.9°. These results indicate that MWCNTs and CuFe2O4 were successfully modified onto the MWCNTs@CuFe2O4-modified ceramic membrane, and the hydrophilicity of the membrane was significantly enhanced.

[0069] 2. Catalytic performance

[0070] Rhodamine B (RhB) was selected as a typical organic pollutant, and static oxidation degradation experiments and dynamic filtration degradation experiments were conducted. Static experiments showed that compared to the significant degradation effect of CuFe₂O₄ powder (86%) on RhB with the same amount of CuFe₂O₄ powder, the CuFeCM membrane exhibited a lower removal efficiency (24%) due to insufficient mass transfer caused by the supported CuFe₂O₄ catalyst. In the dynamic filtration experiment, the CuFeCM membrane achieved a RhB removal rate of 91%, which was 3.8 times that under static conditions and 13.5 times that under PMS oxidation alone, indicating that the synergistic effect of filtration and catalysis significantly enhanced the RhB degradation effect. The CCuFeCM membrane achieved a near 100% RhB removal rate, confirming its excellent catalytic performance.

[0071] 3. Oil-water separation performance

[0072] A dynamic filtration experiment was conducted using a mineral oil emulsion containing RhB as a simulated complex oily wastewater. Regarding the RhB removal efficiency, in the initial 5-minute reaction stage, the degradation rates of RhB by the control group CM membrane and the comparative CuFeCM membrane increased from 0.006 min to 0.006 min. -1 and 0.284min -1 (RhB solution alone) decreased to 0.001 min -1 and 0.266min -1 (Mineral oil emulsion containing RhB). The degradation rate of the CCuFeCM membrane prepared in Example 1 decreased from 0.377 min.-1 Rise to 0.648 min -1 The degradation rate increased by 71%, and the removal rate of RhB reached 100% after 7 minutes of operation. This is because the layered structure of the CCuFeCM membrane effectively blocks oily substances, ensuring that the subsequent confined oxidation process within the membrane pores is not affected by oil droplets. Regarding the fouling trend, the flux decline of the CM membrane, CuFeCM membrane, and CCuFeCM membrane was 43%, 37%, and 18%, respectively, demonstrating that the MWCNT-loaded material can alleviate membrane fouling to some extent, while the CCuFeCM membrane still maintains good antifouling performance.

[0073] 4. Reusability

[0074] The reusability of the CCuFeCM membrane was evaluated through cyclic experiments. After three cycles, the CCuFeCM membrane achieved a 100% removal rate of RhB, a flux decline of 21%, and an oil-water separation efficiency of over 90%, demonstrating good reusability.

[0075] 5. To reveal the mechanism of the synergistic effect of CCuFeCM ceramic membrane in enhancing catalytic activity, free radical quenching experiments and EPR experiments were conducted to verify the main active substances present in the CCuFeCM / PMS oxidation system and their contribution.

[0076] 5.1 Quenching Experiment

[0077] (1) Free radical identification

[0078] SO4 ·- ·OH is the main free radical generated during PMS activation. Quenching agents react differently with different free radicals. Ethanol (EtOH) acts as a quencher for SO42-. ·- The quenchers for ·OH have reaction rate constants of (1.2–2.8) × 10⁻⁶. 9 M -1 ·s -1 and (1.6~7.7)×10 7 M -1 ·s -1 tert-Butanol (TBA) and SO4 ·- The reaction rate constants are (4–9.1) × 10⁻⁶. 5 M -1 ·s -1 The reaction rate constant with ·OH is (3.8~7.6)×10 8 M -1 ·s -1 Therefore, TBA is considered to quench only ·OH, while EtOH can quench SO42-. ·-And ·OH, therefore the contribution of ·OH in the system can be assessed by the removal rate of pollutants during TBA quenching; while SO4 ·- The contribution to the reaction can be assessed by comparing the removal rates of pollutants when quenched with TBA and EtOH, respectively.

[0079] Under the conditions of PMS dosage of 0.1 mM and initial RhB concentration of 5 mg / L, the effects of adding different free radical quenchers on RhB degradation were investigated to identify the types of free radicals in the reaction system. TBA and EtOH were added at 0.3 M. The experimental results are as follows: Figure 2 As shown, without the addition of a quencher, the RhB removal rate was 100% after 20 minutes of reaction. After adding TBA, the RhB removal rate decreased to 96% after 20 minutes of reaction, indicating the presence of ·OH in the system. Furthermore, after adding EtOH, the removal rate decreased to 94%, indicating the presence of SO4 in the system. ·- In summary, SO42- is present in the CCuFeCM / PMS reaction system. ·- And ·OH, and their contribution to RhB degradation in the system is: SO4 ·- >·OH, but SO4 ·- ·OH is not the dominant species for RhB degradation in the system; other active substances also exist in the system.

[0080] (2) Non-radical identification

[0081] Singlet oxygen ( 1 O2) and direct oxidation by PMS are considered to be the main non-radical oxidation mechanisms in the PMS activation process. However, direct oxidation by PMS is difficult to degrade RhB in water. Therefore, 1 O2 is the primary reactive oxygen species responsible for RhB degradation in the CCuFeCM / PMS system. Furfuryl alcohol (FFA) and... 1 The reaction rate constant for O2 is 1.2 × 10⁻⁶. 8 M -1 ·s -1 It is commonly used as a quenching agent to confirm 1 The presence of O2 was observed. The experiment was conducted under conditions of 0.1 mM PMS dosage and an initial RhB concentration of 5 mg / L, with FFA selected as the primary active ingredient. 1 O2 quenchers are used to determine whether there is an O2 quencher in the system. 1 O2 is generated, and the result is as follows: Figure 9 As shown in the figure. Experiments revealed that the addition of 0.3M FFA severely inhibited the RhB degradation reaction, with a removal rate of only 60% after 20 minutes of reaction. This indicates that the CCuFeCM / PMS system not only contains SO42- but also other pollutants. ·- And ·OH, there are also a large number of 1 O2, and 1O2 dominates in the active substances. However, quenching occurs in the system. 1 RhB degradation continued even after O2, indicating the presence of other non-radical processes in the system, such as the formation of MWCNTs / CuFe2O4-PMS complexes and direct electron transfer. Radical quenching experiments confirm the presence of free radicals (SO42-) in the CCuFeCM / PMS system. ·- and ·OH) and non-free radical processes ( 1 The O2 process reduces membrane fouling and improves the removal rate of pollutants in the system.

[0082] 5.2 EPR capture experiment

[0083] Electron paramagnetic resonance (EPR) technology can detect the signals of products formed by specific free radical scavengers and free radicals, thereby identifying active substances in the system. EPR experiments can further verify the formation of active components. 5,5-Dimethyl-1-oxypyrrololine (DMPO), as a spin scavenger, can detect SO42-. ·- The formation of ·OH, and 4-amino-2,2,6,6-tetramethylpiperidine (TEMP) can act as... 1 DMPO acts as an O2 scavenger. It captures ·OH to form a DMPO-·OH complex, typically with a signal intensity ratio of 1:2:2:1. (DMPO and SO4...) ·- The product formed was characterized by six peaks in a 1:1:1:1:1:1 ratio, captured by TEMP. 1 When the products formed by O2 are detected, a 1:1:1 triplet signal peak will appear. For example... Figure 10 As shown, when DMPO is used as the trapping agent and water as the solvent, a typical signal characteristic peak of 1:2:2:1 appears for DMPO-·OH (αH=αN=14.9G), and DMPO-SO4... ·- The characteristic signal peaks of (αN=13.2G, αH=9.6G, αH=1.48G, αH=0.78G) consist of six peaks in a 1:1:1:1:1:1 ratio, appearing near the ·OH peak, indicating that ·OH and SO4 are present in the system. ·- The existence of. Furthermore, such as Figure 11 As shown, when TEMP is used as the trapping agent, the spectrum clearly shows TEMP- 1 The 1:1:1 characteristic triplet signal peak of the O2 (α=17G) adduct further indicates that it was indeed generated in the CCuFeCM / PMS system. 1 O2. In summary, the EPR experimental results are consistent with the previous quenching experimental results, further confirming that the main active species in the CCuFeCM / PMS system is SO4. ·- ·OH and 1 O2.

[0084] 6. Synergistic Mechanism Analysis

[0085] Stable oil droplets in complex oil-water emulsions often compete with target pollutants, consuming active species generated during catalysis and adversely affecting AOPs, leading to decreased degradation performance. The inactivation potential of AOPs in solutions containing multiple pollutants is severely neglected, limiting their application in practical water treatment. Previous studies on the immobilization of nanocatalysts on membranes mainly involved blending or surface coating, which cannot prevent the interference of large organic molecules with subsequent AOPs processes through pre-selective separation. The synergistic mechanism of the carboxylated multi-walled carbon nanotube modified ceramic membrane (MWCNTs@CuFe2O4) prepared in this invention for treating RhB-containing emulsified oily wastewater is as follows: Figure 12 As shown, its excellent catalytic and separation performance is attributed to the innovative design of its layered structure. The hydrophilic MWCNTs layer at the top effectively removes mineral oil while simultaneously improving the membrane's antifouling performance, preventing oil droplets from entering the membrane pores and interfering with subsequent advanced oxidation processes, thus providing protection for the oxidation process. During the catalyst activation of PMS, the mass transfer between PMS and contaminants to the catalyst surface is a crucial rate-limiting step. Under low-pressure drive, the flow process enhances the mass transfer between PMS and contaminants to the catalyst layer within the membrane pores, and the synergistic effect of filtration and catalysis improves the degradation effect of RhB. The carboxylated multi-walled carbon nanotube modified ceramic membrane (MWCNTs@CuFe2O4) prepared in this invention can simultaneously achieve efficient oil-water separation and effective removal of organic pollutants, achieving the effect of modifying ceramic membranes to reduce membrane fouling while removing recalcitrant substances from oily wastewater.

Claims

1. A method for preparing a carboxylated multi-walled carbon nanotube modified ceramic membrane for treating emulsified oil wastewater, characterized in that, Includes the following steps: S1: Prepare the solution; S101: Preparation of impregnation mother liquor: Dissolve the copper source and iron source in deionized water to obtain solution A. Heat the complexing agent to 55-65℃, and then add solution A dropwise to the complexing agent while stirring. After mixing, continue stirring at 55-65℃ for 1-2 hours. Finally, age at room temperature for 10-14 hours to obtain the impregnation mother liquor; the copper source is copper nitrate and the iron source is ferric nitrate. S102: Preparation of carboxylated multi-walled carbon nanotube solution: Dissolve carboxylated multi-walled carbon nanotubes in deionized water and sonicate to obtain a carboxylated multi-walled carbon nanotube solution with a concentration of 0.02-0.05 mg / mL; S2: Immersion coating: Immerse the ceramic membrane in the immersion mother liquor for 10-20 seconds, then rinse with deionized water for 3-5 minutes, and then dry the ceramic membrane at 60-80℃ for 1-2 hours. Repeat the immersion-rinse-drying steps 2-3 times to obtain the coated membrane. S3: Calcination and phase formation: The coated film is calcined at 300-500℃ for 2-5 hours, then naturally cooled to room temperature, rinsed with deionized water for 3-5 minutes, and then dried at 75-85℃ for 2-4 hours to obtain copper ferrite modified film. S4: In-situ deposition: The copper ferrite-modified membrane is loaded into a filtration device and the carboxylated multi-walled carbon nanotube solution is filtered at 0.1-0.3 MPa until the UV254 value of the filtered water is 0, thus obtaining a carboxylated multi-walled carbon nanotube-modified ceramic membrane.

2. The method for preparing carboxylated multi-walled carbon nanotube modified ceramic membrane for emulsified oil wastewater treatment according to claim 1, characterized in that: The concentration of Cu in solution A is 0.15-0.25 mol / L, and the concentration of Fe is 0.35-0.45 mol / L.

3. The method for preparing carboxylated multi-walled carbon nanotube modified ceramic membrane for emulsified oil wastewater treatment according to claim 1, characterized in that: The complexing agent is a citric acid solution with a concentration of 0.5-0.7 mol / L.

4. The method for preparing carboxylated multi-walled carbon nanotube modified ceramic membrane for emulsified oil wastewater treatment according to claim 1, characterized in that: The time required to heat the complexing agent to the target temperature is 25-35 minutes.

5. The method for preparing carboxylated multi-walled carbon nanotube modified ceramic membrane for emulsified oil wastewater treatment according to claim 1, characterized in that: The ultrasonic power in step S102 is 30-50W, and the ultrasonic time is 20-40min.

6. The method for preparing carboxylated multi-walled carbon nanotube modified ceramic membrane for emulsified oil wastewater treatment according to claim 1, characterized in that: Before impregnation, the ceramic membrane is washed 2-3 times with deionized water and then dried at 60-80℃ for 15-25 minutes.

7. The method for preparing carboxylated multi-walled carbon nanotube modified ceramic membrane for emulsified oil wastewater treatment according to claim 1, characterized in that: The calcination temperature is 400℃ and the calcination time is 3.5h.

8. A carboxylated multi-walled carbon nanotube modified ceramic membrane for treating emulsified oil wastewater, prepared by the method according to any one of claims 1-7.

9. The application of the carboxylated multi-walled carbon nanotube modified ceramic membrane according to claim 8 in the treatment of emulsified oil wastewater.

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