A rare earth / carbon-doped titanium suboxide electrode, its preparation method and application

Abstract

This invention discloses a method for preparing a rare-earth / carbon-doped titanium suboxide electrode, comprising: a. mixing titanium suboxide powder, carbon powder, rare earth elements, a binder, and a solvent to obtain a slurry; b. coating the slurry obtained in step a onto a porous titanium substrate and calcining it under an inert atmosphere to obtain the rare-earth / carbon-doped titanium suboxide electrode. The rare-earth / carbon-doped titanium suboxide electrode prepared by this method possesses excellent electrochemical characteristics and stable properties. It also exhibits excellent high-temperature resistance and corrosion resistance, making it suitable for deep treatment applications involving complex pollutants and demanding processing conditions. Furthermore, the raw materials are readily available, the preparation cost is low, the preparation method is simple, and it is easy to apply industrially.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical water treatment technology, specifically relating to a rare earth / carbon-doped titanium suboxide electrode and its preparation method, and particularly to the application of the rare earth / carbon-doped titanium suboxide electrode. Background Technology

[0002] Industrial wastewater contains various toxic and harmful substances, such as heavy metals and organic pollutants, posing serious threats to the environment and human health. It not only pollutes rivers and lakes, disrupting the ecological balance, but may also seep into groundwater, affecting drinking water safety. Furthermore, the harmful substances in industrial wastewater are bioaccumulative, and long-term accumulation in the human body can lead to various diseases. Therefore, timely and effective treatment of industrial wastewater to prevent its harm to the environment and human health has become an urgent priority. Scientific and reasonable methods and strict supervision must be implemented to ensure that industrial wastewater is properly treated. Electrochemical-based deep treatment technologies have broad practical prospects due to their high efficiency, ease of operation, and scalability. However, due to the inherent reaction characteristics of electrochemical technology, it is difficult to combine the reaction features of organic matter removal and desalination.

[0003] In electrochemical reactions, the performance of the anode material is a key factor in reaction efficiency. Anode materials can effectively degrade pollutants through direct and indirect oxidation; therefore, their performance and stability largely determine the efficiency, applicable scenarios, and lifespan of advanced electrochemical oxidation technologies. In recent years, titanium suboxide electrodes have been used as high-efficiency anode materials due to their high oxygen evolution potential (OEP), good conductivity, excellent chemical stability, and ease of preparation. They are inexpensive, pollution-free, and rich in components, making them more cost-effective than boron-doped diamond and noble metal electrodes, and more environmentally friendly than SnO2 and PbO2 electrodes. Due to their unique physical properties, they exhibit excellent catalytic activity and are applied in the electrocatalytic treatment of wastewater. However, titanium suboxide electrodes are prone to passivation during electrocatalysis, leading to a reduction in pollutant removal efficiency.

[0004] Therefore, in order to improve the stability and catalytic efficiency of electrodes and enhance their applicability in practical applications, it is necessary to conduct in-depth research on titanium suboxide electrodes to provide anode materials with both catalytic activity and stability for electrochemical devices. Summary of the Invention

[0005] This invention is based on the inventors' discoveries and understanding of the following facts and problems: doping with rare earth metals and other metal oxides can improve the bonding between the coating and the titanium substrate, effectively preventing the formation of a passivation film, and giving the electrode characteristics such as uniform distribution, fast charge transfer, high oxygen evolution potential, and strong water absorption. However, the high price of rare earths significantly increases the cost of manufacturing electrocatalytic electrodes. Therefore, there is a need to find a low-cost method that can effectively improve the performance of titanium suboxide electrodes.

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a rare-earth / carbon-doped titanium suboxide electrode and its preparation method. The obtained rare-earth / carbon-doped titanium suboxide electrode possesses excellent electrochemical characteristics and stable properties, while also exhibiting excellent high-temperature resistance and corrosion resistance. It is suitable for deep treatment applications involving complex pollutants and demanding processing conditions. Furthermore, the raw materials are readily available, the preparation cost is low, the preparation method is simple, and it is easy to apply industrially.

[0007] The method for preparing a rare earth / carbon-doped titanium suboxide electrode according to an embodiment of the present invention includes:

[0008] a. Mix titanium suboxide powder, carbon powder, rare earth elements, binder, and solvent to prepare a slurry;

[0009] b. The slurry obtained in step a is coated onto a porous titanium substrate and calcined under an inert atmosphere to obtain a rare earth / carbon-doped titanium suboxide electrode.

[0010] The advantages and technical effects of the rare earth / carbon-doped titanium suboxide electrode preparation method of this invention are as follows: 1. In this invention, doping Ce and C in the electrode will generate defects in the titanium suboxide crystal. At the same time, the doping of Ce and C in the electrode leads to changes in the surface electronic structure. The defects in the titanium suboxide crystal and the changes in the surface electronic structure increase the generation efficiency of oxygen vacancies. Therefore, doping Ce and C in the electrode significantly enhances the generation of oxygen vacancies in the electrode, thereby generating more active sites. 2. In this invention, using porous titanium metal as the support layer, rare earth and carbon powder are introduced into the titanium suboxide simultaneously to synthesize a rare earth / carbon-doped titanium suboxide functional layer on the surface of the porous titanium metal. This not only solves the passivation problem of the titanium suboxide electrode in the electrocatalytic process, but also effectively improves the ion transport and electronic conduction performance, improves the efficiency of electrochemical treatment, and improves the removal rate of pollutants. 3. The method of this invention is low in cost, simple in operation, and the rare earth / carbon-doped titanium suboxide electrode has good electrochemical characteristics, stable properties, and excellent high temperature resistance and corrosion resistance. It is suitable for deep treatment fields with complex pollutants and harsh treatment conditions.

[0011] In some embodiments, in step a, the average particle size of the toner is 50-100 μm; the purity of the toner is not less than 99.9 wt%; the rare earth element includes at least one of lanthanum, cerium, and neodymium; the binder includes polyvinylidene fluoride; and the solvent includes at least one of dimethylformamide or dimethyl ethylformamide.

[0012] In some embodiments, in step a, the mass ratio of the sub-titanium oxide, binder, rare earth, toner, and solvent is 4-8:0.5-2:0.5-2:0.5-2:0.5-2.

[0013] In some embodiments, in step b, the coating is performed using a coating machine with a speed of 8-15 mm / s.

[0014] In some embodiments, in step b, the calcination process is carried out under a nitrogen atmosphere, the calcination temperature is 100-150°C, and the calcination time is 15-25 hours.

[0015] In some embodiments, step b, the method for preparing the porous titanium substrate includes: mixing urea and titanium powder in a mortar and stirring to obtain a mixture, then pressing the mixture in a hydraulic press to obtain a membrane, and then calcining it under vacuum to obtain a porous titanium substrate; preferably, the purity of the titanium powder is not less than 99.9 wt%; the average particle size of the titanium powder is 10-50 μm; the average particle size of the urea is 150-450 μm; the pressure of the hydraulic press is 1.5-4 MPa; the vacuum calcination includes: placing the membrane in a heating furnace, maintaining a vacuum of 8-15 Pa, heating it to 400-500 °C at 4-6 °C / min, then cooling it to 20-30 °C with the furnace, and then transferring the membrane to a horizontal carbon tube sintering furnace at a temperature not exceeding 10 °C. -4 The calcination process is carried out under a vacuum of Pa, with a calcination temperature of 1000-1200℃ and a calcination time of 6-10 hours.

[0016] This invention also provides a rare-earth / carbon-doped titanium suboxide electrode, prepared using the method described in this invention. The rare-earth / carbon-doped titanium suboxide electrode of this invention exhibits excellent electrochemical characteristics, stable properties, and superior high-temperature and corrosion resistance, making it suitable for advanced treatment applications involving complex pollutants and demanding processing conditions.

[0017] This invention also provides an electrochemical device, including an anode and a cathode. The anode is a rare earth / carbon-doped titanium suboxide electrode according to this invention, and the cathode is a carbon electrode. An ultraviolet light source is disposed between the cathode and the anode.

[0018] In the device of this invention, a rare-earth / carbon-doped titanium suboxide electrode is used as the anode, which effectively improves ion transport and electron conduction performance, thereby increasing the efficiency of electrochemical treatment. Furthermore, ultraviolet light is introduced into the electrochemical reaction device. During wastewater treatment, dissolved oxygen in the water is reduced on the carbon cathode surface to produce hydrogen peroxide, which reacts with ferrous ions in the water to generate hydroxyl radicals. Hydroxyl radicals can also be generated under ultraviolet light irradiation, efficiently removing organic pollutants. Moreover, ultraviolet light can promote the photochemical reduction of ferric ions to generate ferrous ions, further promoting the electrochemical removal of organic pollutants. The device of this invention effectively improves wastewater treatment efficiency, achieving a COD removal rate of over 80%, and has broad application prospects.

[0019] In some embodiments, the cathode includes a first cathode and a second cathode, the first cathode being a carbon electrode and the second cathode being a stainless steel electrode; the anode is located between the first cathode and the second cathode, and an ultraviolet light source is disposed between the anode and the first cathode.

[0020] In some embodiments, the carbonaceous electrode includes at least one of activated carbon electrode, graphite electrode, and carbon felt electrode; the stainless steel electrode includes at least one of 304 stainless steel electrode or 316 stainless steel electrode; and the ultraviolet light source includes at least one of low-pressure mercury lamp or medium-pressure mercury lamp.

[0021] This invention also provides an electrochemical treatment method for wastewater, using the apparatus described in this invention. This electrochemical treatment method can effectively remove pollutants from wastewater, achieving a COD removal rate of over 80%, and is suitable for advanced treatment applications involving complex pollutants and demanding treatment conditions.

[0022] In some embodiments, the pH of the electrochemical reaction is controlled at 3-5 in the electrochemical treatment method. In some embodiments, ferrous or ferric ions at a concentration of 1 mM to 4 mM are used as a catalyst in the electrochemical treatment method.

[0023] In some embodiments, in the electrochemical treatment method, air or oxygen is introduced into the electrochemical device at a flow rate of 0.5-2 ml / min.

[0024] In some embodiments, the current density in the electrochemical treatment method is 8-12 mA / cm². 2 .

[0025] In some embodiments, the power of the ultraviolet light source is controlled to be 20-30W in the electrochemical treatment method.

[0026] In some embodiments, the wastewater is a landfill leachate nanofiltration concentrate. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the electrochemical device according to an embodiment of the present invention;

[0028] Figure 2 These are morphology and characterization data of the rare earth / carbon-doped titanium suboxide electrode prepared according to the embodiments of the present invention; a is a scanning electron microscope image; b is an energy-dispersive X-ray spectrum; c is X-ray diffraction analysis; d is a Ti 2p X-ray photoelectron spectrum; e is an O1s XPS analysis diagram.

[0029] Figure 3 The graph shows the test results of the wastewater electrochemical treatment method in Example 1;

[0030] Figure 4 The graph shows the test results of the wastewater electrochemical treatment method in Example 2;

[0031] Figure 5 The graph shows the test results of the wastewater electrochemical treatment method in Example 3;

[0032] Figure 6 The graph shows the test results of the wastewater electrochemical treatment method in Example 4;

[0033] Figure 7 The graph shows the test results of the wastewater electrochemical treatment method in Comparative Example 1.

[0034] Figure 8 The figure shows the test results of the wastewater electrochemical treatment method in Comparative Example 2. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] The method for preparing a rare earth / carbon-doped titanium suboxide electrode according to an embodiment of the present invention includes:

[0037] a. Mix titanium suboxide powder, carbon powder, rare earth elements, binder, and solvent to prepare a slurry;

[0038] b. The slurry obtained in step a is coated onto a porous titanium substrate and calcined under an inert atmosphere to obtain a rare earth / carbon-doped titanium suboxide electrode.

[0039] In the preparation method of the rare earth / carbon-doped titanium suboxide electrode of this invention, doping Ce and C into the electrode will generate defects in the titanium suboxide crystal. At the same time, the doping of Ce and C into the electrode leads to changes in the surface electronic structure. The defects in the titanium suboxide crystal and the changes in the surface electronic structure increase the generation efficiency of oxygen vacancies. Therefore, doping Ce and C into the electrode significantly enhances the generation of oxygen vacancies in the electrode, thereby generating more active sites. In this invention, porous titanium metal is used as the support layer. By simultaneously introducing rare earth and carbon powder into the titanium suboxide, a rare earth / carbon-doped titanium suboxide functional layer is synthesized on the surface of the porous titanium metal. This not only solves the passivation problem of the titanium suboxide electrode in the electrocatalytic process, but also effectively improves the ion transport and electronic conduction performance, improves the efficiency of electrochemical treatment, and improves the removal rate of pollutants. The method of this invention is low in cost, simple in operation, and the rare earth / carbon-doped titanium suboxide electrode has good electrochemical characteristics, stable properties, and excellent high temperature resistance and corrosion resistance. It is suitable for deep treatment fields with complex pollutants and harsh treatment conditions.

[0040] In some embodiments, in step a, the average particle size of the carbon powder is 50-100 μm; the purity of the carbon powder is not less than 99.9 wt%; the rare earth element includes at least one of lanthanum, cerium, and neodymium; the binder includes polyvinylidene fluoride; and the solvent includes at least one of dimethylformamide or dimethylacetamide. Preferably, the mass ratio of the titanium suboxide, binder, rare earth element, carbon powder, and solvent is 4-8:0.5-2:0.5-2:0.5-2:0.5-2. In this embodiment of the invention, the ratio of rare earth element, carbon powder, and titanium suboxide is further optimized, which is beneficial to further improve ion transport and electron conduction performance, thereby improving the electrochemical treatment effect. If the amount of carbon powder is too small, it will not be conducive to fully exerting its function; if the amount of carbon powder is too large, it will lead to the preparation solution being too viscous, which is not conducive to electrode preparation and improvement of catalytic performance. If the amount of rare earth element is too small, the improvement on the electrochemical treatment effect will be limited; if the amount of rare earth element is too large, it will be not conducive to the improvement of electron transport and catalytic activity, and will also increase the cost.

[0041] In some embodiments, in step b, the coating is performed using a coating machine with a speed of 8-15 mm / s; the calcination treatment is performed under a nitrogen atmosphere with a calcination temperature of 100-150°C and a calcination time of 15-25 hours.

[0042] In some embodiments, step b, the method for preparing the porous titanium substrate includes: mixing urea and titanium powder in a mortar and stirring to obtain a mixture, then pressing the mixture in a hydraulic press to obtain a membrane, and then calcining it under vacuum to obtain a porous titanium substrate; preferably, the purity of the titanium powder is not less than 99.9 wt%; the average particle size of the titanium powder is 10-50 μm; the average particle size of the urea is 150-450 μm; the pressure of the hydraulic press is 1.5-4 MPa; the vacuum calcination includes: placing the membrane in a heating furnace, maintaining a vacuum of 8-15 Pa, heating it to 400-500 °C at 4-6 °C / min, then cooling it to 20-30 °C with the furnace, and then transferring the membrane to a horizontal carbon tube sintering furnace at a temperature not exceeding 10 °C. -4 The calcination process is carried out under a vacuum of Pa, with a calcination temperature of 1000-1200℃ and a calcination time of 6-10 hours.

[0043] This invention also provides a rare-earth / carbon-doped titanium suboxide electrode, prepared using the method described in this invention. The rare-earth / carbon-doped titanium suboxide electrode of this invention exhibits excellent electrochemical characteristics, stable properties, and superior high-temperature and corrosion resistance, making it suitable for advanced treatment applications involving complex pollutants and demanding processing conditions.

[0044] This invention also provides an electrochemical device, including an anode and a cathode. The anode is a rare earth / carbon-doped titanium suboxide electrode according to this invention, and the cathode is a carbon electrode. An ultraviolet light source is disposed between the cathode and the anode.

[0045] In the device of this invention, a rare-earth / carbon-doped titanium suboxide electrode is used as the anode, which effectively improves ion transport and electron conduction performance, thereby increasing the efficiency of electrochemical treatment. Furthermore, ultraviolet light is introduced into the electrochemical reaction device. During wastewater treatment, dissolved oxygen in the water is reduced on the carbon cathode surface to produce hydrogen peroxide, which reacts with ferrous ions in the water to generate hydroxyl radicals. Hydroxyl radicals can also be generated under ultraviolet light irradiation, efficiently removing organic pollutants. Moreover, ultraviolet light can promote the photochemical reduction of ferric ions to generate ferrous ions, further promoting the electrochemical removal of organic pollutants. The device of this invention effectively improves wastewater treatment efficiency, achieving a COD removal rate of over 80%, and has broad application prospects.

[0046] In some embodiments, the cathode includes a first cathode and a second cathode, the first cathode being a carbon electrode and the second cathode being a stainless steel electrode; the anode is located between the first cathode and the second cathode, and an ultraviolet light source is disposed between the anode and the first cathode. In this embodiment of the invention, two types of cathode plates are disposed in the electrochemical device. The stainless steel cathode plate effectively improves the desalination efficiency, enabling the electrochemical device to simultaneously remove organic matter and salt. This is mainly because introducing ultraviolet light into the electrochemical reaction allows dissolved oxygen in the water to be reduced on the surface of the carbon cathode to produce hydrogen peroxide, which can react with ferrous ions in the water to generate hydroxyl radicals. Hydroxyl radicals can also be generated under ultraviolet light irradiation, efficiently removing organic pollutants. Furthermore, ultraviolet light can promote the photochemical reduction of iron ions to generate ferric ions, promoting the electrochemical removal of organic pollutants. Simultaneously, the carbon cathode can promote ion deposition, achieving partial desalination. On the other side, the stainless steel cathode mainly forms an effective electric field effect with the anode and synergistically promotes ion deposition with the carbon cathode, achieving efficient desalination.

[0047] like Figure 1 As shown, the electrochemical device 1 of the preferred embodiment of the present invention includes an anode 2, a first cathode 3 and a second cathode 4. The first cathode 3 is a carbon electrode and the second cathode 4 is a stainless steel electrode. The anode 2 is located between the first cathode 3 and the second cathode 4, and an ultraviolet light source 5 is provided between the anode 2 and the first cathode 3.

[0048] In some embodiments, the carbonaceous electrode includes at least one of activated carbon electrode, graphite electrode, and carbon felt electrode; the stainless steel electrode includes at least one of 304 stainless steel electrode or 316 stainless steel electrode; and the ultraviolet light source includes at least one of low-pressure mercury lamp or medium-pressure mercury lamp.

[0049] This invention also provides an electrochemical treatment method for wastewater, using the apparatus described in this invention. This electrochemical treatment method can effectively remove pollutants from wastewater, achieving a COD removal rate of over 80%, and is suitable for advanced treatment applications involving complex pollutants and demanding treatment conditions.

[0050] In some embodiments, the pH of the electrochemical reaction is controlled at 3-5 in the electrochemical treatment method. In some embodiments, ferrous or ferric ions at a concentration of 1 mM to 4 mM are used as a catalyst in the electrochemical treatment method.

[0051] In some embodiments, in the electrochemical treatment method, air or oxygen is introduced into the electrochemical device at a flow rate of 0.5-2 ml / min.

[0052] In some embodiments, the current density in the electrochemical treatment method is 8-12 mA / cm². 2 .

[0053] In some embodiments, the power of the ultraviolet light source is controlled to be 20-30W in the electrochemical treatment method.

[0054] In some embodiments, the wastewater is a landfill leachate nanofiltration concentrate.

[0055] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0056] Example 1

[0057] I. Preparation of rare earth / carbon-doped titanium suboxide electrodes

[0058] 1. Preparation of porous titanium substrate: Urea with an average particle size of 300 μm and titanium powder with a particle size of 30 μm and 99.9 wt% were mixed in a mortar and stirred to obtain a mixture. The mixture was then pressed in a hydraulic press at 2 MPa to obtain a membrane. The membrane was placed in a heating furnace and heated to 450 °C at 5 °C / min while maintaining a vacuum of 10 Pa. It was then cooled to room temperature (25 °C) with the furnace. After that, the membrane was transferred to a horizontal carbon tube sintering furnace and heated for 10 minutes. -4 The calcination process was carried out under a vacuum of Pa at a temperature of 1100℃ for 8 hours.

[0059] 2. Mix titanium suboxide powder, polyvinylidene fluoride, carbon powder (purity 99.9wt%), cerium and dimethylformamide in a mass ratio of 6:1:1:1:1 to form a slurry;

[0060] 3. The slurry is poured into an automatic coating machine and uniformly coated onto a porous titanium substrate at a speed of 10 mm / s. Then, it is calcined in a high-temperature furnace at 110°C under a nitrogen atmosphere to obtain a rare earth / carbon-doped titanium suboxide electrode.

[0061] The rare earth / carbon-doped titanium suboxide electrode prepared in this embodiment was characterized, including its morphology and elemental distribution.

[0062] like Figure 2 As shown in Figure a, scanning electron microscopy (SEM) analysis of the rare earth / carbon-doped titanium suboxide electrode shows that the titanium suboxide in the electrode prepared in this embodiment is formed as nanoscale particles.

[0063] Figure 2 Energy dispersive X-ray spectroscopy results of the rare earth / carbon-doped titanium suboxide electrode showed that the main elements in the electrode were Ti, C and Ce.

[0064] Figure 2X-ray diffraction (XRD) analysis results in sample c show that the XRD pattern of the rare-earth / carbon-doped titanium suboxide electrode is similar to that of the titanium suboxide electrode. Furthermore, some diffraction peaks in the rare-earth / carbon-doped titanium suboxide are shifted or weakened. New peaks appear at 22.3° and 32.9°. The XRD results indicate that the addition of Ce and C doping to the electrode introduces defects in the titanium suboxide crystal.

[0065] Figure 2 The Ti 2p X-ray photoelectron spectroscopy (XPS) of the rare earth / carbon-doped sub-titanium oxide electrode showed a shift in the Ti-O binding energy, indicating that the doping of Ce and C in the electrode led to changes in the surface electronic structure.

[0066] Defects in the sub-titanium oxide crystal and changes in the surface electronic structure caused by the introduction of Ce and C in the electrodes can improve the efficiency of oxygen vacancy generation.

[0067] Figure 2 O1s XPS analysis of Ce revealed a significant increase in oxygen vacancy concentration from 18.2% to 36.9%, indicating that Ce and C doping significantly enhanced the generation of oxygen vacancies in the electrode, thereby generating more active sites.

[0068] II. Electrochemical Device

[0069] like Figure 1 As shown, the electrochemical device 1 includes an anode 2, a first cathode 3, and a second cathode 4. The anode 2 is a rare earth / carbon-doped titanium suboxide electrode prepared in this embodiment. The first cathode 3 is a graphite electrode, and the second cathode 4 is a 304 stainless steel electrode. The anode 2 is located between the first cathode 3 and the second cathode 4, and an ultraviolet light source 5 is provided between the anode 2 and the first cathode 3. The ultraviolet light source 5 is a low-pressure mercury lamp.

[0070] III. Electrochemical Treatment Methods for Wastewater

[0071] The landfill leachate nanofiltration concentrate is used as the treatment target, and the electrochemical device of this embodiment is used for multiphase electrochemical treatment.

[0072] The composition of landfill leachate nanofiltration concentrate is shown in Table 1.

[0073] Table 1

[0074] parameter unit numerical values COD mg / L 830 <![CDATA[BOD5]]> mg / L 89 electrical conductivity mS / cm 11.2 <![CDATA[NH3-N]]> mg / L 10.2 chloride ions mg / L 2925.7 pH --- 7.4 calcium ions mg / L 640 magnesium ions mg / L 343

[0075] Processing conditions: The current density used in the electrochemical device is 10 mA / cm². 2The power of the ultraviolet light source was controlled at 25W. Air was introduced into the electrochemical device, and the air flow rate was controlled at 1ml / min during the reaction. Ferrous sulfate was added to the electrochemical device as a catalyst, and the concentration of ferrous ions in the electrochemical device was controlled at 2mM. The pH of the reaction system in the electrochemical device was controlled at 5, and the treatment time was 4 hours.

[0076] Test results are as follows Figure 3 As shown, the experiment was repeated 50 times, and the COD removal rate was basically 91-95%, and the desalination rate was 84-88% (the desalination rate is calculated as: (conductivity of raw water - conductivity of treated water) / conductivity of raw water * 100%).

[0077] As can be seen, the rare earth / carbon-doped titanium suboxide electrode prepared in this embodiment exhibits excellent processing efficiency and stability.

[0078] Example 2

[0079] The method is the same as in Example 1, except that the rare earth element used in step 2 of preparing the rare earth / carbon-doped titanium suboxide electrode is lanthanum.

[0080] The wastewater treatment results in this embodiment are as follows: Figure 4 As shown, the experiment was repeated 50 times, and the COD removal rate was basically 89-92%, and the desalination rate was 79-84%.

[0081] Example 3

[0082] The method is the same as in Example 1, except that the electrochemical device does not include a 304 stainless steel cathode, but only a graphite cathode. That is, the electrochemical device includes an anode and a cathode. The anode is a rare earth / carbon-doped titanium suboxide electrode, and the cathode is a graphite electrode. An ultraviolet light source is placed between the anode and the cathode. The ultraviolet light source is a low-pressure mercury lamp.

[0083] The wastewater treatment results in this embodiment are as follows: Figure 5 As shown, the experiment was repeated 50 times, and the COD removal rate was basically 80-85%, while the desalination rate was 34-40%.

[0084] Example 4

[0085] The method is the same as in Example 1, except that the 304 stainless steel cathode is replaced with a graphite cathode in the electrochemical device, that is, two identical graphite cathodes are used in this example.

[0086] The wastewater treatment results in this embodiment are as follows: Figure 6 As shown, the experiment was repeated 50 times, and the COD removal rate was basically 90-93%, while the desalination rate was 69-73%.

[0087] Comparative Example 1

[0088] The method is the same as in Example 1, except that the electrochemical device does not include a graphite cathode, but only a 304 stainless steel cathode. That is, the electrochemical device includes an anode and a cathode. The anode is a rare earth / carbon-doped titanium suboxide electrode, and the cathode is a 304 stainless steel cathode. An ultraviolet light source is set between the anode and the cathode. The ultraviolet light source is a low-pressure mercury lamp.

[0089] The wastewater treatment results of Comparative Example 1 are as follows Figure 7 As shown, the experiment was repeated 50 times, and the COD removal rate was basically 45-53%, and the desalination rate was 43-48%.

[0090] Comparative Example 2

[0091] The method is the same as in Example 1, except that the preparation step of the rare earth / carbon doped titanium suboxide electrode is omitted, and the anode used in the electrochemical device is a titanium-plated ruthenium-iridium electrode.

[0092] The wastewater treatment results of Comparative Example 2 are as follows Figure 8 As shown, the experiment was repeated 50 times, and the COD removal rate was basically between 43-48%, while the desalination rate was between 34-38%.

[0093] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0094] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a rare earth / carbon-doped titanium suboxide electrode, characterized in that, include: a. Mix titanium suboxide powder, carbon powder, rare earth elements, binder, and solvent to prepare a slurry; b. The slurry obtained in step a is coated onto a porous titanium substrate and calcined under an inert atmosphere to obtain a rare earth / carbon-doped titanium suboxide electrode.

2. The method for preparing the rare earth / carbon-doped sub-titanium oxide electrode according to claim 1, characterized in that, In step a shown, the average particle size of the toner is 50-100 μm; And / or, the purity of the toner is not less than 99.9 wt%; And / or, the rare earth element includes at least one of lanthanum, cerium, and neodymium; And / or, the adhesive comprises polyvinylidene fluoride; And / or, the solvent includes at least one of dimethylformamide or dimethylacetamide; And / or, the mass ratio of the titanium suboxide, binder, rare earth, toner and solvent is 4-8:0.5-2:0.5-2:0.5-2:0.5-2.

3. The method for preparing the rare earth / carbon-doped sub-titanium oxide electrode according to claim 1, characterized in that, In step b, the coating is performed using a coating machine, and the speed of the coating machine is 8-15 mm / s. And / or, the calcination treatment is carried out under a nitrogen atmosphere, the calcination temperature is 100-150 °C, and the calcination time is 15-25 hours.

4. The method for preparing the rare earth / carbon-doped titanium suboxide electrode according to claim 1, characterized in that, In step b, the method for preparing the porous titanium substrate includes: mixing urea and titanium powder in a mortar and stirring to obtain a mixture, then pressing the mixture in a hydraulic press to obtain a membrane, and then calcining it under vacuum to obtain a porous titanium substrate; The purity of the titanium powder is not less than 99.9 wt%; The titanium powder has an average particle size of 10-50 μm; The average particle size of the urea is 150-450 μm; The pressure of the hydraulic press is 1.5-4 MPa; The vacuum calcination includes: placing the diaphragm in a heating furnace, maintaining a vacuum of 8-15 Pa, heating to 400-500 °C at 4-6 °C / min, then cooling it in the furnace to 20-30 °C, and then transferring the diaphragm to a horizontal carbon tube sintering furnace at a temperature not exceeding 10 °C. -4 The calcination process is carried out under a vacuum of 1000-1200 ℃ for 6-10 hours.

5. A rare earth / carbon-doped sub-titanium oxide electrode, characterized in that, It is prepared by any one of claims 1-4.

6. An electrochemical device, characterized in that, It includes an anode and a cathode, wherein the anode is a rare earth / carbon-doped titanium suboxide electrode prepared by any one of claims 1-4 or the rare earth / carbon-doped titanium suboxide electrode of claim 5, the cathode is a carbon electrode, and an ultraviolet light source is disposed between the cathode and the anode.

7. The electrochemical device according to claim 6, characterized in that, The cathode includes a first cathode and a second cathode, wherein the first cathode is a carbon electrode and the second cathode is a stainless steel electrode; The anode is located between the first cathode and the second cathode, and an ultraviolet light source is provided between the anode and the first cathode.

8. The electrochemical device according to claim 7, characterized in that, The carbonaceous electrode includes at least one of activated carbon electrode, graphite electrode, and carbon felt electrode; And / or, the stainless steel electrode includes at least one of 304 stainless steel electrode or 316 stainless steel electrode; And / or, the ultraviolet light source includes at least one of a low-pressure mercury lamp or a medium-pressure mercury lamp.

9. An electrochemical treatment method for wastewater, characterized in that, The apparatus described in any one of claims 6-8 shall be used.

10. The electrochemical treatment method according to claim 9, characterized in that, In the electrochemical treatment method, the pH of the electrochemical reaction is controlled at 3-5; And / or, in the electrochemical treatment method, ferrous ions or ferric ions with a concentration of 1mM~4mM are used as catalysts; And / or, in the electrochemical treatment method, air or oxygen is introduced into the electrochemical device at a flow rate of 0.5-2 ml / min; And / or, in the electrochemical treatment method, the current density is 8-12 mA / cm². 2 ; And / or, in the electrochemical treatment method, the power of the ultraviolet light source is controlled to be 20-30W; And / or, the wastewater is a nanofiltration concentrate of landfill leachate.

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