Rare earth / carbon doped titanium black electrode and preparation method and application thereof

Abstract

The invention discloses a preparation method of a rare earth / carbon doped titanium black electrode, which comprises the following steps: a, mixing titanium black powder, carbon powder, rare earth, a binder and a solvent to prepare slurry; and b, coating a porous titanium substrate with the slurry prepared in the step a, and calcining in an inert atmosphere to prepare the rare earth / carbon doped titanium black electrode. The rare earth / carbon doped titanium black electrode prepared by the preparation method has good electrochemical characteristics, stable properties, excellent high temperature resistance and corrosion resistance, is suitable for the deep treatment field with complex pollutants and harsh treatment conditions, and has the advantages of easily available raw materials, low preparation cost, simple preparation method and easy industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical water treatment, and specifically relates to a rare earth / carbon-doped titania electrode and a preparation method thereof, and particularly relates to the application of the rare earth / carbon-doped titania electrode. Background Art

[0002] Industrial wastewater contains various toxic and harmful substances, such as heavy metals, organic pollutants, etc., which cause serious harm to the environment and human health. It will not only pollute rivers and lakes and destroy the ecological balance, but may also seep into groundwater and affect the safety of drinking water. In addition, the harmful substances in industrial wastewater are bioaccumulative, and long-term accumulation in the human body can cause various diseases. Therefore, it has become a top priority to timely and effectively treat industrial wastewater to prevent its harm to the environment and human health. To this end, scientific and reasonable methods must be adopted and strict supervision must be implemented to ensure that industrial wastewater is properly treated. Electrochemical deep treatment technology has broad practical prospects due to its advantages such as high efficiency, convenient operation and easy scalability. However, due to its own reaction characteristics, electrochemical technology is difficult to have the reaction characteristics of organic matter removal and desalination.

[0003] In the electrochemical reaction process, the performance of the anode material is a key factor in the reaction efficiency. Anode materials can effectively degrade pollutants through direct oxidation and indirect oxidation. Therefore, the performance and stability of anode materials largely determine the efficiency, applicable scenarios and service life of electrochemical advanced oxidation technology. In recent years, titanium dioxide electrodes have been used as high-efficiency anode materials due to their high oxygen evolution potential (OEP), good conductivity, excellent chemical stability and easy preparation. They are cheap, pollution-free and rich in ingredients. Compared with boron-doped diamond and precious metal electrodes, they are more cost-effective and more environmentally friendly than SnO2 and PbO2 electrodes. Due to its unique physical properties, it has good catalytic activity and is used in the field of electrocatalytic wastewater treatment. However, titanium dioxide electrodes are prone to passivation during the electrocatalytic process, resulting in reduced pollutant removal effects.

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

[0005] The present invention is based on the inventor's discovery and understanding of the following facts and problems: doping with metal oxides such as rare earth metals can improve the bonding between the coating and the titanium substrate, effectively prevent the formation of a passivation film, and make the electrode have the characteristics of uniform distribution, fast charge transfer, high oxygen evolution potential, strong water absorption, etc. However, the high price of rare earths significantly increases the cost of making electrocatalytic electrodes, so it is necessary to find a low-cost method that can effectively improve the performance of sub-titanium oxide electrodes.

[0006] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the embodiments of the present invention provide a rare earth / carbon-doped titanium oxide electrode and a preparation method thereof. The prepared rare earth / carbon-doped titanium oxide electrode has good electrochemical properties, stable properties, and excellent high temperature resistance and corrosion resistance. It is suitable for deep treatment fields with complex pollutants and harsh treatment conditions. The raw materials are easily available, the preparation cost is low, the preparation method is simple, and it is easy to apply in industry.

[0007] The method for preparing the rare earth / carbon doped titanium dioxide electrode according to the embodiment of the present invention comprises:

[0008] a. mixing titanium dioxide powder, carbon powder, rare earth, a binder and a solvent to prepare a slurry;

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

[0010] The advantages and technical effects brought by the preparation method of the rare earth / carbon-doped sub-titanium oxide electrode of the embodiment of the present invention are as follows: 1. In the embodiment of the present invention, doping Ce and C in the electrode will produce defects in the sub-titanium oxide crystals. At the same time, the doping of Ce and C in the electrode leads to changes in the surface electronic structure. The defects of the sub-titanium oxide crystals 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 the embodiment of the present invention, porous titanium metal is used as the support layer, and rare earth and carbon powder are simultaneously introduced into the sub-titanium oxide to synthesize a rare earth / carbon-doped sub-titanium oxide functional layer on the surface of the porous titanium metal, which not only solves the passivation problem of the sub-titanium oxide 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 the embodiment of the present invention has low cost and simple operation steps. The prepared rare earth / carbon-doped sub-titanium oxide electrode has good electrochemical properties, stable properties, and excellent high temperature resistance and corrosion resistance, and 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 carbon powder is 50-100 μm; the purity of the carbon powder is not less than 99.9 wt %; the rare earth includes at least one of lanthanum, cerium, and neodymium; the binder includes polyvinylidene fluoride; and the solvent includes at least one of dimethylformamide or dimethylformamide.

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

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

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

[0015] In some embodiments, in step b, the preparation method of the porous titanium substrate comprises: 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 diaphragm, and obtaining a porous titanium substrate after vacuum calcination; preferably, the purity of the titanium powder is not less than 99.9wt%; the average particle size of the titanium powder is 10-50μm; the average particle size of the urea is 150-450μm; the pressure of the hydraulic press is 1.5-4MPa; the vacuum calcination comprises: placing the diaphragm in a heating furnace, heating to 400-500℃ at 4-6℃ / min under a vacuum degree of 8-15Pa, and then cooling to 20-30℃ with the furnace, and then transferring the diaphragm to a horizontal carbon tube sintering furnace at a temperature not higher than 10 -4 The calcination treatment is carried out under a vacuum degree of Pa, the calcination temperature is 1000-1200° C., and the calcination time is 6-10 hours.

[0016] The embodiment of the present invention also provides a rare earth / carbon doped titanium oxide electrode, which is prepared by the method of the embodiment of the present invention. The rare earth / carbon doped titanium oxide electrode of the embodiment of the present invention has good electrochemical properties, stable properties, and excellent high temperature resistance and corrosion resistance, and is suitable for deep treatment fields with complex pollutants and harsh treatment conditions.

[0017] The embodiment of the present invention further provides an electrochemical device, including an anode and a cathode, wherein the anode is the rare earth / carbon-doped titanium dioxide electrode of the embodiment of the present invention, the cathode is a carbonaceous electrode, and an ultraviolet light source is arranged between the cathode and the anode.

[0018] In the device of the embodiment of the present invention, a rare earth / carbon-doped titanium dioxide electrode is used as the anode, which effectively improves the ion transmission and electron conduction performance, improves the efficiency of the electrochemical treatment, and introduces ultraviolet light into the electrochemical reaction device. In the sewage treatment process, the dissolved oxygen in the water is reduced on the surface of the carbon cathode to produce hydrogen peroxide, which can react with the ferrous ions in the water to produce hydroxyl radicals. At the same time, hydroxyl radicals can also be produced under ultraviolet light irradiation, and organic pollutants can be removed efficiently. In addition, ultraviolet light can also promote the photochemical reduction of iron ions to generate ferrous ions, and promote the electrochemical removal of organic pollutants. The device of the embodiment of the present invention effectively improves the sewage treatment effect, and the removal rate of COD in sewage can reach more than 80%, which has broad application prospects.

[0019] In some embodiments, the cathode includes a first cathode and a second cathode, the first cathode is a carbonaceous 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 arranged between the anode and the first cathode.

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

[0021] The present invention also provides an electrochemical treatment method for sewage, which is carried out using the device of the present invention. The electrochemical treatment method of the present invention can effectively remove pollutants in sewage, and the COD removal rate can reach more than 80%, which is suitable for deep treatment fields with complex pollutants and harsh treatment conditions.

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

[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, in the electrochemical treatment method, the current density is 8-12 mA / cm 2 .

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

[0026] In some embodiments, the sewage is landfill leachate nanofiltration concentrate. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 1 is a graph showing the morphology and characterization data of the rare earth / carbon-doped titanium dioxide electrode prepared in the embodiment of the present invention; a is a scanning electron microscope image; b is an energy dispersive X-ray spectrum; c is an X-ray diffraction analysis; d is a Ti 2p X-ray photoelectron spectroscopy spectrum; e is an O1s XPS analysis graph;

[0029] Figure 3 This is a test result diagram of the sewage electrochemical treatment method of Example 1;

[0030] Figure 4 This is a test result diagram of the sewage electrochemical treatment method of Example 2;

[0031] Figure 5 This is a test result diagram of the sewage electrochemical treatment method of Example 3;

[0032] Figure 6 This is a test result diagram of the sewage electrochemical treatment method of Example 4;

[0033] Figure 7 This is a test result diagram of the sewage electrochemical treatment method of Comparative Example 1;

[0034] Figure 8 This is a test result diagram of the sewage electrochemical treatment method of comparative example 2. DETAILED DESCRIPTION

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

[0036] The method for preparing the rare earth / carbon doped titanium dioxide electrode according to the embodiment of the present invention comprises:

[0037] a. mixing titanium dioxide powder, carbon powder, rare earth, a binder and a solvent to prepare a slurry;

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

[0039] In the preparation method of the rare earth / carbon-doped sub-titanium oxide electrode of the embodiment of the present invention, doping Ce and C in the electrode will produce defects in the sub-titanium oxide crystals, and at the same time, the doping of Ce and C in the electrode leads to changes in the surface electronic structure. The defects of the sub-titanium oxide crystals and the changes in the surface electronic structure improve 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; in the embodiment of the present invention, porous titanium metal is used as the support layer, and rare earth and carbon powder are simultaneously introduced into the sub-titanium oxide to synthesize a rare earth / carbon-doped sub-titanium oxide functional layer on the surface of the porous titanium metal, which not only solves the passivation problem of the sub-titanium oxide 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 the embodiment of the present invention has low cost and simple operation steps. The prepared rare earth / carbon-doped sub-titanium oxide electrode has good electrochemical properties, stable properties, and excellent high temperature resistance and corrosion resistance, and 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 includes at least one of lanthanum, cerium, and neodymium; the binder includes polyvinylidene fluoride; and the solvent includes at least one of dimethylformamide or dimethylethylformamide. Preferably, the mass ratio of the titanium oxide, binder, rare earth, carbon powder, and solvent is 4-8: 0.5-2: 0.5-2: 0.5-2: 0.5-2. In the embodiment of the present invention, the ratio of rare earth, carbon powder, and titanium oxide is further optimized, which is conducive to further improving the ion transmission and electronic conductivity performance, thereby improving the electrochemical treatment effect. If the amount of carbon powder is too little, it is not conducive to fully exerting its effect. If the amount of carbon powder is too much, it will cause the preparation liquid to be too viscous, which is not conducive to the preparation of electrodes and the improvement of catalytic performance; if the amount of rare earth is too little, the improvement of the electrochemical treatment effect is limited. If the amount of rare earth is too much, it will be not conducive to the improvement of electronic transmission and catalytic activity, and it will also increase the cost.

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

[0042] In some embodiments, in step b, the preparation method of the porous titanium substrate comprises: 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 diaphragm, and obtaining a porous titanium substrate after vacuum calcination; preferably, the purity of the titanium powder is not less than 99.9wt%; the average particle size of the titanium powder is 10-50μm; the average particle size of the urea is 150-450μm; the pressure of the hydraulic press is 1.5-4MPa; the vacuum calcination comprises: placing the diaphragm in a heating furnace, heating to 400-500℃ at 4-6℃ / min under a vacuum degree of 8-15Pa, and then cooling to 20-30℃ with the furnace, and then transferring the diaphragm to a horizontal carbon tube sintering furnace at a temperature not higher than 10 -4 The calcination treatment is carried out under a vacuum degree of Pa, the calcination temperature is 1000-1200° C., and the calcination time is 6-10 hours.

[0043] The embodiment of the present invention also provides a rare earth / carbon doped titanium oxide electrode, which is prepared by the method of the embodiment of the present invention. The rare earth / carbon doped titanium oxide electrode of the embodiment of the present invention has good electrochemical properties, stable properties, and excellent high temperature resistance and corrosion resistance, and is suitable for deep treatment fields with complex pollutants and harsh treatment conditions.

[0044] The embodiment of the present invention further provides an electrochemical device, including an anode and a cathode, wherein the anode is the rare earth / carbon-doped titanium dioxide electrode of the embodiment of the present invention, the cathode is a carbonaceous electrode, and an ultraviolet light source is arranged between the cathode and the anode.

[0045] In the device of the embodiment of the present invention, a rare earth / carbon-doped titanium dioxide electrode is used as the anode, which effectively improves the ion transmission and electron conduction performance, improves the efficiency of the electrochemical treatment, and introduces ultraviolet light into the electrochemical reaction device. In the sewage treatment process, the dissolved oxygen in the water is reduced on the surface of the carbon cathode to produce hydrogen peroxide, which can react with the ferrous ions in the water to produce hydroxyl radicals. At the same time, hydroxyl radicals can also be produced under ultraviolet light irradiation, and organic pollutants can be removed efficiently. In addition, ultraviolet light can also promote the photochemical reduction of iron ions to generate ferrous ions, and promote the electrochemical removal of organic pollutants. The device of the embodiment of the present invention effectively improves the sewage treatment effect, and the removal rate of COD in sewage can reach more than 80%, which has broad application prospects.

[0046] In some embodiments, the cathode includes a first cathode and a second cathode, the first cathode is a carbonaceous 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 arranged between the anode and the first cathode. In an embodiment of the present invention, two cathode plates are arranged in the electrochemical device, and the arrangement of the stainless steel cathode plate effectively improves the desalination efficiency, so that the electrochemical device can simultaneously remove organic matter and salt. This is mainly because ultraviolet light is introduced into the electrochemical reaction, and the dissolved oxygen in the water is reduced on the surface of the carbon cathode to produce hydrogen peroxide, which can react with ferrous ions in the water to produce hydroxyl radicals, and can also produce hydroxyl radicals under ultraviolet light irradiation, so as to efficiently remove organic pollutants, and ultraviolet light can promote the photochemical reduction of iron ions to generate iron ions, so as to promote the electrochemical removal of organic pollutants, and at the same time, the carbon cathode can promote ion deposition, so as to achieve the purpose of partial desalination. The stainless steel cathode on the other side mainly forms an effective electric field effect with the anode, and cooperates with the carbon cathode to promote ion deposition, so as to achieve efficient desalination.

[0047] like Figure 1 As shown, the electrochemical device 1 of a 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 carbonaceous electrode, 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 arranged between the anode 2 and the first cathode 3.

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

[0049] The present invention also provides an electrochemical treatment method for sewage, which is carried out using the device of the present invention. The electrochemical treatment method of the present invention can effectively remove pollutants in sewage, and the COD removal rate can reach more than 80%, which is suitable for deep treatment fields with complex pollutants and harsh treatment conditions.

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

[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, in the electrochemical treatment method, the current density is 8-12 mA / cm 2 .

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

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

[0055] The present invention is described in detail below with reference to the embodiments and the accompanying drawings.

[0056] Example 1

[0057] 1. Preparation of rare earth / carbon-doped titanium dioxide 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 and stirred in a mortar to obtain a mixture, and then the mixture was pressed in a hydraulic press at 2 MPa to obtain a membrane, and the membrane was placed in a heating furnace and heated to 450°C at 5°C / min under a vacuum of 10 Pa, and then cooled to room temperature (25°C) with the furnace, and then the membrane was transferred to a horizontal carbon tube sintering furnace and sintered at 10 -4 The calcination treatment was carried out under a vacuum degree of Pa, the calcination temperature was 1100° C., and the calcination time was 8 hours.

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

[0060] 3. The slurry was inverted into an automatic coating machine, and the slurry was evenly coated on the porous titanium substrate at a speed of 10 mm / S, and then calcined in a high-temperature furnace at 110° C. in a nitrogen atmosphere to obtain a rare earth / carbon-doped titania electrode.

[0061] The rare earth / carbon doped titania electrode prepared in this example was characterized, including morphology and element distribution.

[0062] like Figure 2 As shown in a, the scanning electron microscope (SEM) analysis of the rare earth / carbon doped titanium oxide electrode shows that the titanium oxide in the electrode prepared in this example is formed in the form of nano-scale particles.

[0063] Figure 2 The energy dispersive X-ray spectroscopy results of the rare earth / carbon-doped titania electrode in b show that the main elements in the electrode mainly contain Ti, C and Ce.

[0064] Figure 2The X-ray diffraction analysis (XRD) results in c show that the XRD pattern of the rare earth / carbon doped titania electrode is similar to that of the titania electrode. In addition, some diffraction peaks of the rare earth / carbon doped titania were shifted or weakened. New peaks appeared at 22.3° and 32.9°. The XRD results show that the addition of Ce and C doping in the electrode will produce defects in the titania crystals.

[0065] Figure 2 d Ti 2p X-ray photoelectron spectroscopy (XPS) spectrum of the rare earth / carbon-doped titania electrode shows that a shift in the Ti-O binding energy is observed, indicating that the doping of Ce and C in the electrode leads to a change in the surface electronic structure.

[0066] The defects of TiO2 crystals and the changes in the surface electronic structure caused by the introduction of Ce and C in the electrode can improve the generation efficiency of oxygen vacancies.

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

[0068] 2. 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 sub-titanium oxide electrode prepared in this embodiment, the first cathode 3 is a graphite electrode, 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 arranged between the anode 2 and the first cathode 3, and the ultraviolet light source 5 adopts a low-pressure mercury lamp.

[0070] 3. Electrochemical treatment of sewage

[0071] The landfill leachate nanofiltration concentrate was used as the treatment object, and the electrochemical device of this embodiment was used to perform multiphase electrochemical treatment.

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

[0073] Table 1

[0074] parameter unit Numeric COD mg / L 830 <![CDATA[BOD5]]> mg / L 89 Conductivity mS / cm 11.2 <![CDATA[NH3-N]]> mg / L 10.2 Chloride ion mg / L 2925.7 pH --- 7.4 Calcium mg / L 640 Magnesium ion mg / L 343

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

[0076] Test results such as 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 was calculated as: (conductivity of raw water - conductivity of treated water) / conductivity of raw water * 100%).

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

[0078] Example 2

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

[0080] The sewage treatment results of 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 that in Example 1, except that the electrochemical device does not include a 304 stainless steel cathode, and only uses a graphite cathode, that is, the electrochemical device includes an anode and a cathode, the anode is a rare earth / carbon-doped titania electrode, the cathode is a graphite electrode, and an ultraviolet light source is arranged between the anode and the cathode, and the ultraviolet light source uses a low-pressure mercury lamp.

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

[0084] Example 4

[0085] The method is the same as that of 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 embodiment.

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

[0087] Comparative Example 1

[0088] The method is the same as that in Example 1, except that the electrochemical device does not include a graphite cathode, and only uses 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 dioxide electrode, the cathode is a 304 stainless steel cathode, and an ultraviolet light source is arranged between the anode and the cathode, and the ultraviolet light source uses a low-pressure mercury lamp.

[0089] The sewage 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 that of Example 1, except that the step of preparing the rare earth / carbon-doped titanium suboxide electrode is eliminated, and the anode used in the electrochemical device is a titanium-plated ruthenium-iridium electrode.

[0092] The sewage 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%, and the desalination rate was between 34-38%.

[0093] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0094] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

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

2. The method for preparing the rare earth / carbon doped titanium dioxide electrode according to claim 1, characterized in that: In step a, the average particle size of the carbon powder is 50-100 μm; and / or, the purity of the carbon powder is not less than 99.9wt%; And / or, the rare earth includes at least one of lanthanum, cerium and neodymium; and / or, the binder comprises polyvinylidene fluoride; and / or, the solvent comprises at least one of dimethylformamide or dimethylformamide; And / or, the mass ratio of the titanium oxide, the binder, the rare earth, the carbon powder and the 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 titanium dioxide electrode according to claim 1, characterized in that: In the step b, the coating is performed by a coating machine, and the speed of the coating machine is 8-15 mm / s; And / or, the calcination treatment is carried out in 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 dioxide electrode according to claim 1, characterized in that: In the step b, the method for preparing the porous titanium substrate comprises: 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 vacuum calcining to obtain a porous titanium substrate; Preferably, the purity of the titanium powder is not less than 99.9wt%; Preferably, the average particle size of the titanium powder is 10-50 μm; Preferably, the average particle size of the urea is 150-450 μm; Preferably, the pressure of the hydraulic press is 1.5-4MPa; Preferably, the vacuum calcination comprises: placing the membrane in a heating furnace, heating to 400-500°C at 4-6°C / min under a vacuum of 8-15 Pa, then cooling to 20-30°C with the furnace, and then transferring the membrane to a horizontal carbon tube sintering furnace at a temperature not higher than 10 -4 The calcination treatment is carried out under a vacuum degree of Pa, the calcination temperature is 1000-1200° C., and the calcination time is 6-10 hours.

5. A rare earth / carbon doped titanium dioxide electrode, characterized in that: The method according to any one of claims 1 to 4 is adopted to prepare the present invention.

6. An electrochemical device, characterized in that: The invention comprises an anode and a cathode, wherein the anode is a rare earth / carbon-doped titanium oxide electrode prepared by the method according to any one of claims 1 to 4 or a rare earth / carbon-doped titanium oxide electrode according to claim 5, the cathode is a carbonaceous electrode, and an ultraviolet light source is arranged between the cathode and the anode.

7. The electrochemical device according to claim 6, characterized in that The cathode comprises a first cathode and a second cathode, the first cathode is a carbonaceous 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 arranged 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 an activated carbon electrode, a graphite electrode, and a carbon felt electrode; And / or, the stainless steel electrode includes at least one of a 304 stainless steel electrode or a 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. A method for electrochemical treatment of sewage, characterized in that: The method is carried out using the device described in any one of claims 6 to 8.

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 to be 3-5; And / or, in the electrochemical treatment method, ferrous ions or ferric ions with a concentration of 1 mM to 4 mM 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 / cm 2 ; And / or, in the electrochemical treatment method, the power of the ultraviolet light source is controlled to be 20-30W; And / or, the sewage is nanofiltration concentrate of landfill leachate.

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