A titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, its preparation method and application

Abstract

This invention provides a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, its preparation method, and its application, belonging to the field of water treatment technology. This invention prepares a highly ordered TiO2 nanotube array as an intermediate coating on a porous Ti substrate after acidification pretreatment. This not only increases the inter-coating stress and improves the adhesion between the Ti substrate and the metal oxide coating, enhancing the material's mechanical strength, but also enhances the electron transport rate. This invention obtains rutile tetragonal β-PbO2 through electrodeposition, exhibiting good electrocatalytic activity. Doping PbO2 with Ce element gives the metal oxide coating high catalytic activity. The titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane of this invention has a dense and uniform coating, high specific surface area, and certain water permeability. It can achieve simultaneous filtration and catalytic degradation in continuous flow mode, and has good decolorization treatment efficiency for organic dye wastewater.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, its preparation method, and its application. Background Technology

[0002] Currently, there is a significant demand for dye wastewater discharge from industries such as dyeing, textiles, and papermaking. This wastewater typically has complex characteristics, containing dyes that exhibit carcinogenic, mutagenic, and teratogenic effects. These dyes are highly stable and also resistant to light and oxidation; direct discharge without treatment will cause significant harm to plants and animals. Common treatment methods for these pollutants include physical methods (membrane separation, adsorption, ion exchange), chemical methods (photocatalysis, coagulation), and biodegradation technologies. However, these technologies are constrained by various conditions, including the failure of physical methods to reduce toxicity, the limitation of catalyst activity in photocatalysis by wastewater color, and the extremely high requirements for temperature and pH in biodegradation technologies. Electrochemical Advanced Oxidation Processes (EAOPs) have become a promising wastewater treatment technology due to their mild treatment conditions, fewer limitations, and minimal secondary pollution. This technology involves two processes: firstly, initiating a direct electron transfer reaction on the anode material surface to catalyze the degradation of pollutants; and secondly, generating oxidizing free radicals in the vicinity of the anode material to indirectly oxidize pollutants. Both reactions are continuous.

[0003] Metal oxide membranes are a type of inorganic membrane characterized by stable properties, high mechanical strength, and excellent catalytic performance. They are manufactured from metal powder through molding and high-temperature sintering, thus exhibiting good conductivity and physicochemical stability. Dimensionally Stable Anodes (DSA electrodes), using inexpensive titanium as a substrate, are dimensionally stable electrodes characterized by stable performance and low cost. They typically consist of a layer of catalytically active metal oxides, such as IrO2, RuO2, and PbO2, loaded onto the surface of a titanium substrate. Due to their high electrocatalytic activity, high cost-effectiveness, and long lifespan, they have become ideal anode materials in the field of electrocatalysis. Among these, PbO2 electrodes, as a typical inactive DSA electrode, possess numerous advantages, including high oxygen evolution potential, high conductivity, corrosion resistance, simple preparation process, and low cost, making them widely used in water treatment industries such as phenolic wastewater and dye wastewater treatment. PbO2 mainly exists in nature in two forms: orthorhombic α-PbO2 and rutile tetragonal β-PbO2. β-PbO2 exhibits higher catalytic activity and is therefore more suitable as a catalytic coating for current water treatment applications. However, due to the limitations of foamed Ti substrates, catalytic coatings directly loaded onto them often suffer from poor adhesion. This inherent defect makes the active coating on Ti / PbO2 electrodes prone to peeling and electrode deactivation, making them unsuitable for long-term, continuous, and harsh water treatment applications. This severely restricts the development of Ti / PbO2 anodes in the field of advanced wastewater treatment. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, its preparation method and application. The titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared by this invention is suitable for long-term, continuous, high-intensity application and has good decolorization treatment efficiency for organic dye wastewater.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, comprising the following steps:

[0007] The porous filter Ti substrate was immersed in an acidification solution to undergo acidification treatment, resulting in an acidified substrate.

[0008] The acidified substrate is immersed in a first electrolyte and subjected to first anodic oxidation to obtain a pre-oxidized substrate;

[0009] The pre-oxidized substrate was immersed in a second electrolyte and subjected to a second anodic oxidation. After calcination, a Ti substrate with a titanium dioxide nanotube array was obtained.

[0010] The Ti substrate with the titanium dioxide nanotube array was placed in a deposition solution and electrodeposited to obtain a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane.

[0011] The first electrolyte and the second electrolyte independently comprise a soluble fluorine source, ethylene glycol, and water;

[0012] The sedimentation solution consists of a soluble lead source, a soluble cerium source, a fluorine source, and an acid solution.

[0013] Preferably, the porous filter Ti substrate has a thickness of 0.3–1 mm, a pore size of 5–50 μm, and a porosity of ≥30%.

[0014] Preferably, the acidification solution comprises hydrofluoric acid, nitric acid, and water;

[0015] The volume ratio of hydrofluoric acid to nitric acid is 1:1 to 5, and the volume ratio of hydrofluoric acid to water is 1:5 to 25.

[0016] The acidification treatment is performed at a temperature of 20–30°C for 10–15 seconds.

[0017] Preferably, the mass ratio of soluble fluoride source to water in the first electrolyte is 1:2.3 to 4.3, and the mass ratio of soluble fluoride source to ethylene glycol is 0.004 to 0.006:1.

[0018] The voltage for the first anodizing is 50–100V, the time is 0.5–1.5h, and the distance between the anode and cathode plates is 2–5cm.

[0019] Preferably, the mass ratio of soluble fluoride source to water in the second electrolyte is 1:4.5 to 6.5, and the mass ratio of soluble fluoride source to ethylene glycol is 0.001 to 0.003:1.

[0020] The voltage for the second anodizing is 50-100V, the time is 3-6h, and the distance between the anode and cathode plates is 2-5cm.

[0021] Preferably, the calcination temperature is 200–550°C, and the holding time is 1.5–3 hours.

[0022] Preferably, the Pb in the sedimentation solution 2+ Concentrations range from 10 to 300 g / L, Ce 3+ The concentration is 0.35–0.55 g / L, F - The concentration is 0.4–0.6 g / L;

[0023] The electrode spacing for electrode deposition is 0.5–3.5 cm, and the current density is 5–50 mA / cm². 2The deposition time is 5 to 45 minutes.

[0024] The present invention provides a titanium dioxide nanotube array-cerium-doped lead dioxide coating filter membrane prepared by the above preparation method, comprising a porous filter Ti substrate, a titanium dioxide nanotube array grown on the surface of the porous filter Ti substrate, and a cerium-doped lead dioxide coating attached to the surface of the titanium dioxide nanotube array.

[0025] This invention provides the application of the above-mentioned titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane in the treatment of organic wastewater.

[0026] Preferably, the organic matter in the organic wastewater includes one or more of Congo red, methyl orange, and methylene blue.

[0027] This invention provides a method for preparing a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, comprising the following steps: immersing a porous Ti substrate in an acidification solution for acidification treatment to obtain an acidified substrate; immersing the acidified substrate in a first electrolyte for first anodic oxidation to obtain a pre-oxidized substrate; immersing the pre-oxidized substrate in a second electrolyte for second anodic oxidation, followed by calcination to obtain a Ti substrate with a grown titanium dioxide nanotube array; and placing the Ti substrate with the grown titanium dioxide nanotube array in a deposition solution for electrodeposition to obtain a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane (denoted as Ti / TiO2NTAs / PbO2-Ce). This invention prepares a highly ordered TiO2 nanotube array (TiO2 NTAs) as an intermediate coating on a porous Ti substrate after acidification pretreatment. This not only enhances the inter-coating stress and improves the adhesion between the Ti substrate and the metal oxide coating, thereby increasing the material's mechanical strength and extending its service life, but also enhances the electron transport rate. This invention also employs electrodeposition of a cerium-doped lead dioxide coating (PbO2-Ce). The electrodeposited lead dioxide is rutile tetragonal β-PbO2, exhibiting excellent electrocatalytic activity. Doping PbO2 with Ce imparts high catalytic activity to the metal oxide coating. The resulting titanium dioxide nanotube array-cerium-doped lead dioxide coating filter membrane is dense, uniform, and has a high specific surface area. It possesses a certain degree of water permeability and can achieve simultaneous filtration and catalytic degradation in continuous flow mode, demonstrating excellent decolorization efficiency for organic dye wastewater.

[0028] Furthermore, the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane provided by this invention can adapt to long-term, continuous, high-intensity applications. It has good water flux in continuous flow operation mode, achieves simultaneous and efficient filtration and degradation of organic dyes, is easy to operate, does not introduce other chemical additives, and has high decolorization efficiency without secondary pollution. Attached Figure Description

[0029] Figure 1 SEM-Mapping image of the titanium dioxide array nanotubes prepared in Example 1;

[0030] Figure 2 Cross-sectional view of the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared in Example 1;

[0031] Figure 3 The image shows a SEM-Mapping of the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared in Example 2.

[0032] Figure 4 The XRD test results are for the titanium dioxide array nanotubes prepared in Example 1;

[0033] Figure 5 The XRD test results are for the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared in Example 2.

[0034] Figure 6 The pure water flux of the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared in Example 1 at different flow rates

[0035] Figure 7 The decolorization behavior of methylene blue at different times. Detailed Implementation

[0036] This invention provides a method for preparing a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, comprising the following steps:

[0037] The porous filter Ti substrate was immersed in an acidification solution to undergo acidification treatment, resulting in an acidified substrate.

[0038] The acidified substrate is immersed in a first electrolyte and subjected to first anodic oxidation to obtain a pre-oxidized substrate;

[0039] The pre-oxidized substrate was immersed in a second electrolyte and subjected to a second anodic oxidation. After calcination, a Ti substrate with a titanium dioxide nanotube array was obtained.

[0040] The Ti substrate with the titanium dioxide nanotube array was placed in a deposition solution and electrodeposited to obtain a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane.

[0041] The first electrolyte and the second electrolyte independently comprise a soluble fluorine source, ethylene glycol, and water;

[0042] The sedimentation solution consists of a soluble lead source, a soluble cerium source, a fluorine source, and an acid solution.

[0043] In this invention, a porous filter Ti substrate is immersed in an acidification solution to undergo acidification treatment, thereby obtaining an acidified substrate.

[0044] In this invention, the thickness of the porous filter Ti substrate is preferably 0.3-1 mm, more preferably 0.6 mm; the pore size is preferably 5-50 μm, more preferably 20-30 μm; and the porosity is preferably ≥30%, more preferably 30-50%.

[0045] In this invention, the acidification treatment solution preferably comprises hydrofluoric acid, nitric acid, and water. The volume ratio of hydrofluoric acid to nitric acid is preferably 1:1 to 5, more preferably 1:2 to 4; the volume ratio of hydrofluoric acid to water is preferably 1:5 to 25, more preferably 1:10 to 21. The acidification treatment temperature is preferably 20 to 30°C, and the treatment time is preferably 10 to 15 seconds. After the acidification treatment, the surface of the resulting acidified substrate forms a uniformly rough, grayish-brown texture. The purpose of the acidification treatment in this invention is to remove the oxide layer on the surface of the porous filter Ti substrate and enhance the adhesion between the substrate and the coating.

[0046] Following the acidification treatment, the resulting acidified substrate is preferably dried. In this invention, the drying is preferably vacuum drying, with the vacuum drying temperature preferably between 60 and 130°C, more preferably between 80 and 100°C; and the drying time preferably between 1 and 3 hours, more preferably 2 hours.

[0047] After obtaining the acidified substrate, the present invention immerses the acidified substrate in a first electrolyte and performs a first anodic oxidation to obtain a pre-oxidized substrate. In the present invention, the first electrolyte comprises a soluble fluoride source, ethylene glycol, and water, wherein the soluble fluoride source is preferably ammonium fluoride and / or hydrofluoric acid. In the present invention, the mass ratio of the soluble fluoride source to water in the first electrolyte is preferably 1:2.3 to 4.3, more preferably 1:3 to 4; the mass ratio of the soluble fluoride source to ethylene glycol is preferably 1:0.4% to 0.6%, more preferably 1:0.5%.

[0048] In this invention, the counter electrode used for the first anodizing is preferably one of Pt, C, and Ti. In this invention, the voltage for the first anodizing is preferably 50–100V, more preferably 60–80V; the time is preferably 0.5–1.5h, more preferably 0.8–1.2h; and the distance between the anode and cathode plates is preferably 2–5cm, more preferably 3–4cm.

[0049] In this invention, after the first anodizing, the resulting pre-oxidized substrate is preferably dried. The drying is preferably vacuum drying, with the vacuum drying temperature preferably between 60 and 130°C, more preferably between 80 and 100°C; and the drying time preferably between 1 and 3 hours, more preferably 2 hours.

[0050] After obtaining the pre-oxidized substrate, the present invention immerses the pre-oxidized substrate in a second electrolyte for a second anodic oxidation, followed by calcination to obtain a Ti substrate with a titanium dioxide nanotube array grown on it. In the present invention, the second electrolyte comprises a soluble fluorine source, ethylene glycol, and water, wherein the soluble fluorine source is preferably ammonium fluoride and / or hydrofluoric acid. In the present invention, the mass ratio of the soluble fluorine source to water in the second electrolyte is preferably 1:4.5–6.5, more preferably 1:5–6; the mass ratio of the soluble fluorine source to ethylene glycol is preferably 1:0.1%–0.3%, more preferably 1:0.2%.

[0051] In this invention, the counter electrode used for the second anodizing is preferably one of Pt, C, and Ti. In this invention, the voltage for the second anodizing is preferably 50–100V, more preferably 60–80V; the time is preferably 3–6h, more preferably 4–5h; and the distance between the anode and cathode plates is preferably 2–5cm, more preferably 3–4cm.

[0052] In this invention, after the second anodizing, the resulting pre-oxidized substrate is preferably dried. The drying is preferably vacuum drying, with the vacuum drying temperature preferably between 60 and 130°C, more preferably between 80 and 100°C, and the drying time preferably between 1 and 3 hours, more preferably 2 hours.

[0053] This invention grows a highly ordered TiO2 nanotube array (TiO2 NTAs) on the surface of a porous Ti substrate through the first and second anodizing processes. This increases the specific surface area to a certain extent, provides more attachment sites for PbO2, and enables the material to have more active sites available for reaction, thereby improving catalytic efficiency.

[0054] In this invention, the calcination is preferably carried out in an air atmosphere, and the calcination temperature is preferably 200–550°C, more preferably 300–450°C; the holding time is preferably 1.5–3 h, more preferably 2–2.5 h. In this invention, the heating rate to the calcination temperature is preferably 5°C / min. Through the calcination, the TiO2 array after anodizing transforms into anatase. In this invention, among the three crystal structures of TiO2, the anatase type is more stable than the rutile and brookite types, exhibits special phenomena such as macroscopic quantum tunneling effects, and has more electron holes and electron defects. The generated oxygen vacancies can effectively promote electron transfer. Therefore, when anatase TiO2NTAs are used as an intermediate layer, their highly ordered nanotube array structure will improve the current situation of nonlinear electron transfer between the porous filter Ti substrate and the PbO2 catalytic coating, increase the electron transfer rate, and further enhance the catalytic processing capacity.

[0055] After obtaining the Ti substrate with the grown titanium dioxide nanotube array, the present invention places the Ti substrate with the grown titanium dioxide nanotube array in a deposition solution and performs electrodeposition to obtain a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane. In the present invention, the deposition solution comprises a soluble lead source, a soluble cerium source, a fluorine source, and an acid solution. In the present invention, the soluble lead source is preferably lead nitrate, the soluble cerium source is preferably cerium nitrate; the fluorine source is preferably sodium fluoride or Nafion solution, the acid solution is preferably a nitric acid solution, and the concentration of the nitric acid solution is preferably 1-5 wt%, more preferably 2-4 wt%.

[0056] In this invention, the Pb in the sedimentation solution 2+ The preferred concentration is 10–300 g / L, more preferably 50–200 g / L; Ce 3 + The preferred concentration is 0.35–0.55 g / L, more preferably 0.4–0.5 g / L; F - The concentration is preferably 0.4 to 0.6 g / L, more preferably 0.5 g / L.

[0057] In this invention, the electrode spacing for electrode deposition is preferably 0.5–3.5 cm, more preferably 1.5–3 cm; the current density is preferably 5–50 mA / cm². 2 More preferably 20–40 mA / cm 2 The deposition time is preferably 5 to 45 minutes, more preferably 15 to 30 minutes.

[0058] The present invention provides a titanium dioxide nanotube array-cerium-doped lead dioxide coating filter membrane prepared by the above preparation method, comprising a porous filter Ti substrate, a titanium dioxide nanotube array (TiO2 NTAs) grown on the surface of the porous filter Ti substrate, and a cerium-doped lead dioxide coating (PbO2-Ce) attached to the surface of the titanium dioxide nanotube array.

[0059] In this invention, the crystal structure of the titanium dioxide nanotube array is preferably anatase; the thickness of the titanium dioxide nanotube array is preferably 2.5–4.5 μm, more preferably 3–4 μm; the diameter of a single titanium dioxide nanotube is preferably 1–80 nm, more preferably 5–60 nm, and even more preferably 10–50 nm.

[0060] In this invention, the thickness of the cerium-doped lead dioxide coating is preferably 60–120 μm, more preferably 80–100 μm. In this invention, the lead dioxide in the cerium-doped lead dioxide coating is preferably rutile tetragonal β-PbO2.

[0061] This invention provides the application of the above-mentioned titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane in the treatment of organic wastewater. In this invention, the organic wastewater is preferably organic dye wastewater. In this invention, the organic matter in the organic wastewater includes one or more of Congo red, methyl orange, and methylene blue.

[0062] In this invention, the method of application preferably includes the following steps:

[0063] Organic wastewater is mixed with electrolyte to obtain wastewater to be treated;

[0064] Using the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane as the anode and the macroporous Ti mesh as the cathode, the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane and the macroporous Ti mesh are placed in a filtration device, and an external power supply is connected so that the wastewater to be treated passes through the filtration device, and the wastewater to be treated is electrocatalytically degraded at the same time as filtration.

[0065] In this invention, the electrolyte is preferably sodium sulfate and / or sulfuric acid. In this invention, the concentration of the electrolyte in the wastewater to be treated is preferably 20–80 mmol / L, more preferably 40–60 mmol / L.

[0066] In this invention, the spacing between the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane and the macroporous Ti mesh is preferably 1-15 mm, more preferably 5-10 mm. In this invention, the voltage of the external power supply is preferably 3-10 V, more preferably 5-8 V. In this invention, the flow rate of the wastewater to be treated through the filtration device is preferably 0.5-5 mL / min, more preferably 1-3 mL / min.

[0067] The following detailed description, in conjunction with embodiments, illustrates the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, its preparation method, and its application, but these should not be construed as limiting the scope of protection of this invention.

[0068] Example 1

[0069] The preparation method of titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane includes the following steps:

[0070] Acidification pretreatment of porous foam Ti filter substrate:

[0071] (1) Substrate pretreatment: The porous filter Ti substrate (thickness 0.5 mm, average pore size 20 μm) was immersed in a mixture of HF, HNO3 and H2O with a volume ratio of 1:3:21 for 10-15 seconds until a uniformly rough gray surface appeared on the substrate. After washing with deionized water, it was vacuum dried at 80℃ for 2 hours.

[0072] Preparation of Ti / TiO2 NTAs intermediate layer:

[0073] (1) Preparation of electrolyte 1: Dissolve 0.5g of NH4F in 2mL of deionized water and dilute to 100mL with ethylene glycol;

[0074] (2) First anodizing: Using the pretreated material as the anode and Ti as the counter electrode, the plate spacing is controlled at 3 cm. The material is oxidized in electrolyte 1 for 1 h under a voltage of 60 V and then washed with deionized water.

[0075] (3) Preparation of electrolyte 2: Dissolve 0.2g of NH4F in 1mL of deionized water and dilute to 100mL with ethylene glycol;

[0076] (4) Second anodizing: Using the material after the first anodizing as the anode and Ti as the counter electrode, the plate spacing is controlled at 3 cm. The material is oxidized in electrolyte 2 for 4 h at a voltage of 60 V, and then washed with deionized water. After vacuum drying at 80 °C for 2 h, it is calcined at 450 °C for 2 h to obtain Ti / TiO2 NTAs.

[0077] Preparation of Ti / TiO2 NTAs / PbO2-Ce surface-active coating:

[0078] (1) Preparation of sedimentation solution: Add 40g Pb(NO3)2, 0.11g Ce(NO3)3, and 0.12g NaF to a 1% nitric acid solution and bring the volume to 250mL.

[0079] (2) Metal oxide coating loading: Using the Ti / TiO2 NTAs prepared in Example 1 as the anode and Ti as the counter electrode, the current density was controlled at 30 mA / cm². 2 A titanium dioxide array nanotube metal oxide coating filter membrane with a PbO2 coating was obtained by deposition for 40 min at an electrode spacing of 1.0 cm. This membrane is denoted as Ti / TiO2 NTAs / PbO2-Ce.

[0080] Example 2

[0081] The preparation method of titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane includes the following steps:

[0082] Acidification pretreatment of porous foam Ti filter substrate:

[0083] (1) Substrate pretreatment: The porous filter Ti substrate (thickness 0.6 mm, average pore size 20 μm) was immersed in a mixture of HF, HNO3 and H2O with a volume ratio of 1:4:23 for 10-15 seconds until a uniformly rough gray surface appeared on the substrate. After washing with deionized water, it was vacuum dried at 90℃ for 2 hours.

[0084] Preparation of Ti / TiO2 NTAs intermediate layer:

[0085] (1) Preparation of electrolyte 1: Dissolve 0.46g of NH4F in 1.8mL of deionized water and make up to 100mL with ethylene glycol;

[0086] (2) First anodizing: Using the pretreated material as the anode and Ti as the counter electrode, the plate spacing is controlled at 4 cm. The material is oxidized in electrolyte 1 for 1.2 h under a voltage of 65 V and then washed with deionized water.

[0087] (3) Preparation of electrolyte 2: Dissolve 0.25g of NH4F in 1.3mL of deionized water and dilute to 100mL with ethylene glycol;

[0088] (4) Second anodizing: Using the material after the first anodizing as the anode and Ti as the counter electrode, the plate spacing is controlled at 4 cm. The material is oxidized in electrolyte 2 at a voltage of 65 V for 3.8 h, washed with deionized water, vacuum dried at 90 °C for 2 h, and then calcined at 420 °C for 2 h to obtain Ti / TiO2 NTAs.

[0089] Preparation of Ti / TiO2 NTAs / PbO2-Ce surface-active coating:

[0090] (1) Preparation of sedimentation solution: Add 50g Pb(NO3)2, 0.13g Ce(NO3)3, and 0.13g NaF to a 1% nitric acid solution and bring the volume to 250mL.

[0091] (2) Metal oxide coating loading: Using the Ti / TiO2 NTAs prepared in Example 1 as the anode and Ti as the counter electrode, the current density was controlled at 20 mA / cm². 2 A titanium dioxide array nanotube metal oxide coating filter membrane with a PbO2 coating was obtained by deposition for 35 min at an electrode spacing of 1.5 cm. This membrane is denoted as Ti / TiO2NTAs / PbO2-Ce.

[0092] Structural characterization

[0093] The SEM-Mapping image of the titanium dioxide array nanotubes prepared in Example 1 is shown below. Figure 1 As can be seen, the prepared nanotubes exhibit high orderliness, with diameters ranging from 1.5 to 50 nm.

[0094] Cross-sectional view of the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared in Example 1 is shown below. Figure 2 It can be seen that the length of the titanium dioxide array nanotubes is between 3000 and 4000 nm.

[0095] The SEM-Mapping image of the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared in Example 2 is shown below. Figure 3 PbO2 loading was observed inside the pore.

[0096] The XRD test results of the titanium dioxide array nanotubes prepared in Example 1 are shown in the figure. Figure 4 As can be seen, TiO2 is obtained after anodizing.

[0097] The XRD test results of the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared in Example 2 are shown in the figure. Figure 5 Analysis showed that the active coating was β-PbO2.

[0098] Test Example 1

[0099] The Ti / TiO2 NTAs / PbO2-Ce material was prepared as described in Example 1 and placed in a filtration device. A peristaltic pump was used to control the outflow rate, and the pure water flux at different flow rates was measured. (See attached figure.) Figure 6 .Depend on Figure 6 It can be seen that the flow rate is 1 mL·min -1 The pure water flux of the material is approximately 190 L·m -2 •h, as the flow rate increases to 3mL·min -1 The pure water flux increases simultaneously, reaching approximately 730 L·m⁻².-2 The result of ·h indicates that the Ti / TiO2 NTAs / PbO2-Ce prepared in this invention can maintain a certain level of water permeability at different flow rates.

[0100] Test Example 2

[0101] A methylene blue solution with a concentration of 50 mg / L and containing 50 mM Na2SO4 electrolyte was prepared as the organic dye in the aqueous solution. The material prepared in Example 2 was used as the anode, and a macroporous Ti mesh was used as the cathode, with a 5 mm gap between them placed longitudinally in the filter device. An external regulated DC power supply provided a constant 5V electric field. A peristaltic pump was connected to the outlet pipe to control the flow rate at 1 mL / min. Filtration began simultaneously with the applied voltage. The methylene blue decolorization behavior at different times was as follows: Figure 7 As shown, the decolorization rate is approximately 55% after 45 minutes, and the decolorization rate of methylene blue exceeds 80% after 120 minutes of filtration and degradation.

[0102] Test Example 3

[0103] Using the materials Ti / PbO2-Ce and Ti / TiO2 NTAs / PbO2-Ce prepared in Examples 1 and 2, 0.25 M H2SO4 was used as the electrolyte, and 0.1 A·cm was applied. -2 A constant current was applied, with a voltage rise of 5V as the endpoint, to test the effect of the intermediate TiO2 NTAs on the accelerated service life of the material. The results showed that under these conditions, Ti / PbO2-Ce could only be used for a few hours, while the Ti / TiO2 NTAs / PbO2-Ce material with the intermediate layer loaded could be used for tens to hundreds of hours. Therefore, the presence of the intermediate TiO2 NTAs effectively improves the material's bonding strength and extends its service life.

[0104] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane, comprising the following steps: The porous filter Ti substrate was immersed in an acidification solution to undergo acidification treatment, resulting in an acidified substrate. The acidified substrate is immersed in a first electrolyte and subjected to first anodic oxidation to obtain a pre-oxidized substrate; The pre-oxidized substrate was immersed in a second electrolyte and subjected to a second anodic oxidation. After calcination, a Ti substrate with a titanium dioxide nanotube array was obtained. The Ti substrate with the titanium dioxide nanotube array grown thereon was placed in a deposition solution and electrodeposited to obtain a titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane. The first electrolyte and the second electrolyte independently comprise a soluble fluorine source, ethylene glycol, and water; The composition of the deposition solution includes a soluble lead source, a soluble cerium source, a fluorine source, and an acid solution; The length of the titanium dioxide nanotubes is 3000~4000 nm; The acidification solution comprises hydrofluoric acid, nitric acid, and water; The volume ratio of hydrofluoric acid to nitric acid is 1:1~5, and the volume ratio of hydrofluoric acid to water is 1:5~25. The acidification treatment is performed at a temperature of 20-30°C for 10-15 seconds. The mass ratio of soluble fluoride source to water in the first electrolyte is 1:2.3~4.3, and the mass ratio of soluble fluoride source to ethylene glycol is 0.004~0.006:

1. The voltage for the first anodizing is 50~100V, the time is 0.5~1.5h, and the distance between the anode and cathode plates is 2~5cm; The mass ratio of soluble fluoride source to water in the second electrolyte is 1:4.5~6.5, and the mass ratio of soluble fluoride source to ethylene glycol is 0.001~0.003:

1. The voltage for the second anodizing is 50~100V, the time is 3~6h, and the distance between the anode and cathode plates is 2~5cm.

2. The preparation method according to claim 1, characterized in that, The porous filter Ti substrate has a thickness of 0.3~1mm, a pore size of 5~50μm, and a porosity of ≥30%.

3. The preparation method according to claim 1, characterized in that, The calcination temperature is 200~550℃, and the holding time is 1.5~3h.

4. The preparation method according to claim 1, characterized in that, Pb in the sediment 2+ Concentrations range from 10 to 300 g / L, Ce 3+ The concentration is 0.35~0.55 g / L, F - The concentration is 0.4~0.6 g / L; The electrode spacing for electrode deposition is 0.5~3.5cm, and the current density is 5~50mA / cm. 2 The deposition time is 5~45 min.

5. The titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane prepared by the preparation method according to any one of claims 1 to 4 comprises a porous filter Ti substrate, a titanium dioxide nanotube array grown on the surface of the porous filter Ti substrate, and a cerium-doped lead dioxide coating attached to the surface of the titanium dioxide nanotube array.

6. The application of the titanium dioxide nanotube array-cerium-doped lead dioxide coated filter membrane according to claim 5 in the treatment of organic wastewater.

7. The application according to claim 6, characterized in that, The organic matter in the organic wastewater includes one or more of Congo red, methyl orange, and methylene blue.

Images