A method for electrocatalytic oxidation of organic wastewater

Abstract

The present invention provides an electrocatalytic oxidation method for organic wastewater, the electrocatalytic oxidation method comprising the following steps: under aeration conditions, using a metal-supported catalyst for electrocatalytic oxidation treatment of organic wastewater, the residence time of the organic wastewater is 60-240min, and the gas-water volume ratio is (1-2): 1; during electrocatalytic oxidation, the spacing between the anode plate and the cathode plate is 15-25mm; the substrates of the anode plate and the cathode plate are independently titanium alloys, and the surface coatings are independently iridium-ruthenium alloys or iridium-tantalum alloys with a thickness of 8-12μm. The electrocatalytic oxidation method provided by the present invention controls the parameters of the electrocatalytic oxidation process so that when it treats organic wastewater with COD≥15000mg / L, the value of BOD5 / COD can be increased to 0.6, so that the organic wastewater has biodegradability.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection and relates to a wastewater treatment method, in particular to an electrocatalytic oxidation method for organic wastewater. Background Art

[0002] High-concentration organic wastewater has the characteristics of high COD content and complex composition. The methods for treating it include conventional biochemical method, advanced oxidation method and combined biochemical method.

[0003] Conventional biochemical methods use a combination of biological filters and O / A / O contact oxidation treatment processes to separate high-concentration wastewater from low-concentration wastewater. High-concentration wastewater is first pumped into an anaerobic biological filter for anaerobic hydrolysis, then flows into a multi-stage contact oxidation tank for aerobic biochemical treatment, and then passes through a medium sedimentation tank for mud and water separation. The effluent is then mixed with low-concentration wastewater for anaerobic hydrolysis, and then enters a mixed sewage contact oxidation tank for aerobic biochemical treatment. Finally, it passes through a secondary sedimentation tank for mud and water separation, and the effluent meets the discharge standard. However, due to the poor biodegradability of high-concentration organic wastewater, the actual effect deviates greatly from the ideal effect.

[0004] The advanced oxidation methods commonly used in industry include wet oxidation, photocatalytic oxidation and Fenton oxidation. Wet oxidation requires high temperatures above 125°C and high pressure conditions not exceeding 20MPa, and has the disadvantage of high operating costs. Photocatalytic oxidation treatment of organic wastewater has the advantages of being economical and green, but it is greatly limited by the turbidity of the sewage, has low treatment efficiency, and is only suitable for treating low-concentration organic wastewater.

[0005] Fenton oxidation method uses Fenton reagent to oxidize and remove refractory organic matter. The working principle is that H2O2 reacts with Fe 2 + The hydroxyl radical ·OH with high reactivity is generated under the catalytic action of ·OH, which can react with most organic matter to degrade it. It oxidizes and decomposes organic matter into small molecules through pathways such as electron transfer. 2+ Oxidized to Fe 3+ However, the Fenton oxidation process will produce a large amount of iron-containing sludge, and there are great safety hazards in the presence and use of hydrogen peroxide.

[0006] CN 111573913A discloses a method for treating benzotriazole salt-containing wastewater with electrocatalytic oxidation: adding a composite agent to the benzotriazole salt-containing wastewater to adjust the pH to 7-9; electrocatalytically oxidizing the benzotriazole salt-containing wastewater after adjusting the pH to obtain pre-treated wastewater; and post-treating the obtained pre-treated wastewater to obtain treated wastewater. The method achieves the adjustment of the pH value of the benzotriazole salt-containing wastewater by adding the composite agent, and the total salt content does not increase significantly, reducing the influence of impurity ions on the electrocatalytic oxidation, and the COD removal rate of the benzotriazole salt-containing wastewater after adjusting the pH value is as high as 96.79%. However, the above method requires the additional addition of the composite agent, and can only adjust the benzotriazole salt-containing wastewater with a COD not exceeding 12000 mg / L.

[0007] CN 104176798A discloses a method and device for treating high-concentration wastewater by electrocatalytic oxidation, which comprises a reaction pool, an electrode and a composite catalyst. Several reaction pools are respectively provided with water inlets and outlets, an air inlet pipe and a special alloy electrode combination and a composite catalyst active particle filler, and a suitable water and air distribution system is arranged. Electrocatalytic oxidation is performed on the basis of an integrated separation reactor composed of several reaction pool devices. Under normal temperature and pressure conditions, high-concentration organic wastewater that is difficult to biodegrade is completely mineralized into carbon dioxide and water, or while degrading polluting organic matter, the B / C of the wastewater is increased to make the wastewater biodegradable. However, the cost of the device is high, and a specific composite catalyst is also required, which makes it difficult to apply industrially.

[0008] CN102126804A discloses a method for degrading high-concentration organic wastewater. The method firstly passes the wastewater into an electrolytic cell for electrocatalytic oxidation, and controls the current density to be 1×10 -3 -1×10 -2 A / m 2 ; After electrolysis, it is passed into the flotation tank, and ozone is introduced under the stirring of the flotation machine, and the ozone flow rate is controlled at 1L / min; finally, it is adsorbed by activated carbon, filtered by microfiltration membrane and ultrafiltration membrane, and finally the qualified industrial wastewater with COD degraded to less than 50mg / L is obtained. However, the above method requires the addition of ozone, the cost of ozone is relatively high, and the operator needs to take additional protection when using ozone.

[0009] Therefore, it is necessary to provide an electrocatalytic oxidation method for organic wastewater with simple COD removal operation and suitable for industrial use. Summary of the invention

[0010] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for electrocatalytic oxidation of organic wastewater. The electrocatalytic oxidation method is simple to operate, and by controlling the parameters in the electrocatalytic oxidation process, the method can treat organic wastewater with COD ≥ 15000 mg / L, increase the BOD5 / COD value of the organic wastewater to 0.6, and make the organic wastewater biodegradable.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] The present invention provides an electrocatalytic oxidation method for organic wastewater, which comprises the following steps: using a metal-supported catalyst to electrocatalytically oxidize and treat the organic wastewater under aeration conditions, wherein the residence time of the organic wastewater is 60-240 min and the gas-water volume ratio is (1-2):1;

[0013] During the electrocatalytic oxidation, the distance between the anode plate and the cathode plate is 15-25 mm;

[0014] The substrates of the anode plate and the cathode plate are independently made of titanium alloy, and the surface coatings are independently made of iridium-ruthenium alloy or iridium-tantalum alloy with a thickness of 8-12 μm.

[0015] The gas used in the aeration conditions of the present invention is air.

[0016] When the electrocatalytic oxidation method of the present invention is carried out, the spacing between the anode plate and the cathode plate is 15-25 mm, for example, it can be 15 mm, 16 mm, 18 mm, 20 mm, 21 mm, 24 mm or 25 mm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 18-21 mm.

[0017] When the electrocatalytic oxidation method of the present invention is carried out, the surface coating thickness of the anode plate is 8-12 μm, for example, it can be 8 μm, 9 μm, 10 μm, 11 μm or 12 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] When the electrocatalytic oxidation method of the present invention is carried out, the surface coating thickness of the cathode plate is 8-12 μm, for example, it can be 8 μm, 9 μm, 10 μm, 11 μm or 12 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] When the electrocatalytic oxidation method of the present invention is carried out, the residence time of the organic wastewater is 60-240 min, for example, it can be 60 min, 80 min, 100 min, 120 min, 150 min, 180 min, 200 min, 210 min, or 240 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] The gas-water volume ratio of the present invention is (1-2):1, for example, it can be 1:1, 1.2:1, 1.5:1, 1.6:1, 1.8:1 or 2:1, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. The unit of the gas-water volume ratio is Nm 3 / L.

[0021] The electrocatalytic oxidation method provided by the present invention controls the parameters of the electrocatalytic oxidation process so that when treating organic wastewater with COD≥15000mg / L, the value of BOD5 / COD can be increased to 0.6, making the organic wastewater biodegradable.

[0022] Preferably, the thickness of the anode plate is 1-2 mm, for example, 1 mm, 1.2 mm, 1.5 mm, 1.6 mm, 1.8 mm or 2 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the thickness of the cathode plate is 1-2 mm, for example, 1 mm, 1.2 mm, 1.5 mm, 1.6 mm, 1.8 mm or 2 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] Preferably, during the electrocatalytic oxidation treatment, the inter-plate voltage is 28-32V, for example, 28V, 29V, 30V, 31V or 32V, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] Preferably, the current density during the electrocatalytic oxidation treatment is 1000-1500 A / m 2 , for example, it can be 1000A / m 2 、1050A / m 2 、1100A / m 2 、1150A / m 2 , 1200A / m 2 、1250A / m 2 、1300A / m 2 、1350A / m 2 、1400A / m 2 、1450A / m2 or 1500A / m 2 , but not limited to the listed values, other values ​​not listed in the numerical range are also applicable, preferably 1200-1400A / m 2 .

[0026] Preferably, the metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate.

[0027] Preferably, the metal oxide includes any one of CeO2, SnO2, TiO2, NiO2 or ZnO or a combination of at least two of them. Typical but non-limiting combinations include a combination of CeO2 and SnO2, a combination of TiO2 and NiO2, a combination of TiO2, NiO2 and ZnO, a combination of CeO2, SnO2 and ZnO, a combination of CeO2, SnO2, TiO2 and NiO2, or a combination of CeO2, SnO2, TiO2, NiO2 and ZnO, preferably a combination of CeO2 and TiO2.

[0028] Preferably, the mass ratio of the metal oxide to the activated carbon substrate is 1:(30-40), for example, it can be 1:30, 1:32, 1:33, 1:35, 1:36, 1:38 or 1:40, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the mass ratio of CeO2 to TiO2 is (3-5):1, for example, it can be 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the method for preparing the metal supported catalyst comprises the following steps:

[0031] An equal volume of a metal salt solution is impregnated into an activated carbon substrate, and then calcined after ultrasonic vibration to obtain the metal-supported catalyst;

[0032] The metal salt solution contains metal oxides dissolved in a prescribed amount.

[0033] The present invention does not impose too many restrictions on the method for dissolving the metal oxide, as long as the dissolution of the metal oxide can be achieved.

[0034] Preferably, the shape of the activated carbon substrate includes any one of columnar, strip or spherical.

[0035] Preferably, the calcination temperature is 450-500°C, for example, 450°C, 460°C, 470°C, 480°C, 490°C or 500°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the calcination time is 3-5 h, for example, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the activated carbon substrate is an activated carbon substrate pretreated with acid.

[0038] Preferably, the acid pretreatment comprises the following steps: soaking the activated carbon in nitric acid, washing it and then performing heat treatment to obtain the activated carbon substrate.

[0039] Preferably, the mass concentration of the nitric acid is 60-65wt%, for example, it can be 60wt%, 61wt%, 62wt%, 63wt%, 64wt% or 65wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the soaking time is 1-2 hours, for example, 1 hour, 1.2 hours, 1.5 hours, 1.6 hours, 1.8 hours or 2 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the temperature of the heat treatment is 200-240°C, for example, 200°C, 210°C, 220°C, 230°C or 240°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the heat treatment time is 1-2 h, for example, 1 h, 1.2 h, 1.5 h, 1.6 h, 1.8 h or 2 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the COD concentration of the organic wastewater is 15000-25000 mg / L, for example, it can be 15000 mg / L, 16000 mg / L, 17000 mg / L, 18000 mg / L, 19000 mg / L, 20000 mg / L, 21000 mg / L, 22000 mg / L, 23000 mg / L, 24000 mg / L or 25000 mg / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] The BOD5 / COD of the organic wastewater is ≤0.1, for example, it can be 0.01, 0.03, 0.05, 0.08 or 0.1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] Preferably, the BOD5 of organic wastewater treated by the present invention is ≤1000 mg / L, for example, it can be 100 mg / L, 300 mg / L, 500 mg / L, 600 mg / L, 800 mg / L or 1000 mg / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] Preferably, the pH value of the organic wastewater is 6-8, for example, 6, 6.5, 7, 7.5 or 8, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0047] Preferably, the chloride ion content of the organic wastewater is ≤5000 ppm, for example, it can be 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500 or 5000, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] When the total salt content of the treated organic wastewater is insufficient, sodium sulfate can be used as the electrolyte.

[0049] As a preferred technical solution of the electrocatalytic oxidation method of the present invention, the electrocatalytic oxidation method comprises the following steps:

[0050] Under aeration conditions, metal-supported catalysts are used for electrocatalytic oxidation treatment of organic wastewater. The residence time of organic wastewater is 60-240 min, and the gas-water volume ratio is (1-2):1. During electrocatalytic oxidation, the distance between the anode plate and the cathode plate is 15-25 mm, the inter-plate voltage is 28-32 V, and the current density is 1000-1500 A / m 2 The thickness of the anode plate and the cathode plate is 1-2 mm, the substrates of the anode plate and the cathode plate are independently titanium alloy, and the surface coatings are independently iridium-ruthenium alloy or iridium-tantalum alloy with a thickness of 8-12 μm;

[0051] The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate, wherein the mass ratio of the metal oxide to the activated carbon substrate is 1:(30-40); the preparation method of the metal-supported catalyst comprises the following steps:

[0052] An activated carbon substrate is impregnated with an equal volume of a metal salt solution, and then calcined at 450-500° C. for 3-5 hours after ultrasonic vibration to obtain the metal-supported catalyst; the metal salt solution contains a metal oxide dissolved in a formula amount;

[0053] The preparation method of the activated carbon substrate comprises the following steps: soaking the activated carbon in nitric acid with a mass concentration of 60-65wt% for 1-2h, and heat treating at 200-240°C for 1-2h after washing to obtain the activated carbon substrate.

[0054] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The electrocatalytic oxidation method provided by the present invention is simple to operate. It can achieve the treatment of organic wastewater with COD≥15000mg / L by simply controlling the parameters of the electrocatalytic oxidation process, and can increase the BOD5 / COD value of the organic wastewater to 0.6, making the organic wastewater biodegradable. DETAILED DESCRIPTION

[0057] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0058] Example 1

[0059] This embodiment provides an electrocatalytic oxidation method for organic wastewater, and the electrocatalytic oxidation method comprises the following steps:

[0060] Under aeration conditions, metal-supported catalysts were used to electrocatalytically oxidize organic wastewater with a COD concentration of 20,000 mg / L, a pH value of 7, and a BOD5 concentration of 500 mg / L. The chloride ion content in the organic wastewater was 3200 ppm. The residence time of the organic wastewater was 150 min, and the gas-water volume ratio was 1.5:1. During electrocatalytic oxidation, the distance between the anode plate and the cathode plate was 20 mm, the inter-plate voltage was 30 V, and the current density was 1250 A / m 2 The thickness of the anode plate and the cathode plate is 1.5 mm, respectively. The substrates of the anode plate and the cathode plate are independently titanium alloy, and the surface coating is independently iridium-ruthenium alloy with a thickness of 10 μm.

[0061] The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate, wherein the mass ratio of the metal oxide to the activated carbon substrate is 1:35; the metal oxide is CeO2 and TiO2 in a mass ratio of 4:1; and the preparation method of the metal-supported catalyst comprises the following steps:

[0062] An equal volume of a metal salt solution is impregnated into a columnar activated carbon substrate, and the columnar activated carbon substrate is calcined at 480° C. for 4 hours after ultrasonic vibration to obtain the metal-supported catalyst; the metal salt solution contains a metal oxide dissolved in a formula amount;

[0063] The preparation method of the activated carbon substrate comprises the following steps: soaking the activated carbon in nitric acid with a mass concentration of 62wt% for 1.5h, and heat-treating the activated carbon at 220°C for 1.5h after washing to obtain the activated carbon substrate.

[0064] Example 2

[0065] This embodiment provides an electrocatalytic oxidation method for organic wastewater, and the electrocatalytic oxidation method comprises the following steps:

[0066] Under aeration conditions, the metal-supported catalyst was used to electrocatalytically oxidize the organic wastewater. The composition of the organic wastewater was the same as that in Example 1. The residence time of the organic wastewater was 120 min, and the gas-water volume ratio was 1.8:1. During the electrocatalytic oxidation, the distance between the anode plate and the cathode plate was 18 mm, the inter-plate voltage was 29 V, and the current density was 1400 A / m 2 The thickness of the anode plate and the cathode plate is 1.2 mm, respectively. The substrates of the anode plate and the cathode plate are titanium alloy, respectively. The surface coating is iridium-ruthenium alloy with a thickness of 9 μm.

[0067] The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate, wherein the mass ratio of the metal oxide to the activated carbon substrate is 1:30; the metal oxide is CeO2 and TiO2 in a mass ratio of 3:1; and the preparation method of the metal-supported catalyst comprises the following steps:

[0068] An equal volume of a metal salt solution is impregnated into a columnar activated carbon substrate, and then calcined at 450° C. for 5 hours after ultrasonic vibration to obtain the metal-supported catalyst; the metal salt solution contains a metal oxide dissolved in a formula amount;

[0069] The preparation method of the activated carbon substrate comprises the following steps: soaking the activated carbon in nitric acid with a mass concentration of 60wt% for 2h, and heat-treating it at 200°C for 2h after washing to obtain the activated carbon substrate.

[0070] Example 3

[0071] This embodiment provides an electrocatalytic oxidation method for organic wastewater, and the electrocatalytic oxidation method comprises the following steps:

[0072] Under aeration conditions, the metal-supported catalyst was used to electrocatalytically oxidize the organic wastewater. The composition of the organic wastewater was the same as that in Example 1. The residence time of the organic wastewater was 180 min, and the gas-water volume ratio was 1.2:1. During the electrocatalytic oxidation, the distance between the anode plate and the cathode plate was 21 mm, the inter-plate voltage was 31 V, and the current density was 1200 A / m 2 The thickness of the anode plate and the cathode plate is 1.8 mm, respectively. The substrates of the anode plate and the cathode plate are titanium alloy, respectively. The surface coating is iridium-ruthenium alloy with a thickness of 11 μm, respectively.

[0073] The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate, wherein the mass ratio of the metal oxide to the activated carbon substrate is 1:40; the metal oxide is CeO2 and TiO2 in a mass ratio of 5:1; and the preparation method of the metal-supported catalyst comprises the following steps:

[0074] An equal volume of a metal salt solution is impregnated into a columnar activated carbon substrate, and then calcined at 500° C. for 3 hours after ultrasonic vibration to obtain the metal-supported catalyst; the metal salt solution contains a metal oxide dissolved in a formula amount;

[0075] The preparation method of the activated carbon substrate comprises the following steps: soaking the activated carbon in nitric acid with a mass concentration of 65wt% for 1 hour, and then heat-treating it at 240°C for 1 hour after washing to obtain the activated carbon substrate.

[0076] Example 4

[0077] This embodiment provides a method for electrocatalytic oxidation of organic wastewater, which is the same as that of Embodiment 1 except that the mass of TiO2 in the metal oxide is replaced by CeO2.

[0078] Example 5

[0079] This embodiment provides a method for electrocatalytic oxidation of organic wastewater, which is the same as that of Embodiment 1 except that CeO2 and other components in the metal oxide are replaced by TiO2.

[0080] Example 6

[0081] This embodiment provides a method for electrocatalytic oxidation of organic wastewater, which is the same as that of Embodiment 1 except that the activated carbon substrate is activated carbon that has not been pretreated with acid.

[0082] Example 7

[0083] This embodiment provides an electrocatalytic oxidation method for organic wastewater, which is the same as that of Embodiment 1 except that the surface coating of the anode plate is an iridium-tantalum alloy with a thickness of 10 μm.

[0084] Example 8

[0085] This embodiment provides an electrocatalytic oxidation method for organic wastewater, and the electrocatalytic oxidation method comprises the following steps:

[0086] Under aeration conditions, metal-supported catalysts were used to electrocatalytically oxidize organic wastewater with a COD concentration of 15000 mg / L, a pH value of 6, and a BOD5 concentration of 800 mg / L. The chloride ion content in the organic wastewater was 2800 ppm. The residence time of the organic wastewater was 60 min, and the gas-water volume ratio was 2:1. During electrocatalytic oxidation, the distance between the anode plate and the cathode plate was 15 mm, the inter-plate voltage was 28 V, and the current density was 1500 A / m 2 The thickness of the anode plate and the cathode plate is 1 mm, the substrates of the anode plate and the cathode plate are titanium alloy, and the surface coating is iridium-ruthenium alloy with a thickness of 8 μm.

[0087] The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate, wherein the mass ratio of the metal oxide to the activated carbon substrate is 1:35; the metal oxide is CeO2 and TiO2 in a mass ratio of 4:1; and the preparation method of the metal-supported catalyst comprises the following steps:

[0088] An equal volume of a metal salt solution is impregnated into a columnar activated carbon substrate, and the columnar activated carbon substrate is calcined at 480° C. for 4 hours after ultrasonic vibration to obtain the metal-supported catalyst; the metal salt solution contains a metal oxide dissolved in a formula amount;

[0089] The preparation method of the activated carbon substrate comprises the following steps: soaking the activated carbon in nitric acid with a mass concentration of 62wt% for 1.5h, and heat-treating the activated carbon at 220°C for 1.5h after washing to obtain the activated carbon substrate.

[0090] Example 9

[0091] This embodiment provides an electrocatalytic oxidation method for organic wastewater, and the electrocatalytic oxidation method comprises the following steps:

[0092] Under aeration conditions, metal-supported catalysts were used to electrocatalytically oxidize organic wastewater with a COD concentration of 25000 mg / L, a pH value of 8, and a BOD5 concentration of 600 mg / L. The chloride ion content in the organic wastewater was 3600 ppm. The residence time of the organic wastewater was 240 min, and the gas-water volume ratio was 1:1. During electrocatalytic oxidation, the distance between the anode plate and the cathode plate was 25 mm, the inter-plate voltage was 32 V, and the current density was 1000 A / m 2 The thickness of the anode plate and the cathode plate is 2 mm, respectively, the substrates of the anode plate and the cathode plate are titanium alloy, and the surface coating is iridium-ruthenium alloy with a thickness of 12 μm;

[0093] The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate, wherein the mass ratio of the metal oxide to the activated carbon substrate is 1:35; the metal oxide is CeO2 and TiO2 in a mass ratio of 4:1; and the preparation method of the metal-supported catalyst comprises the following steps:

[0094] An equal volume of a metal salt solution is impregnated into a columnar activated carbon substrate, and the columnar activated carbon substrate is calcined at 480° C. for 4 hours after ultrasonic vibration to obtain the metal-supported catalyst; the metal salt solution contains a metal oxide dissolved in a formula amount;

[0095] The preparation method of the activated carbon substrate comprises the following steps: soaking the activated carbon in nitric acid with a mass concentration of 62wt% for 1.5h, and heat-treating the activated carbon at 220°C for 1.5h after washing to obtain the activated carbon substrate.

[0096] Example 10

[0097] This embodiment provides an electrocatalytic oxidation method for organic wastewater, which is the same as that of Embodiment 1 except that nitric acid in the acid pretreatment is replaced by 98 wt % sulfuric acid.

[0098] Comparative Example 1

[0099] This comparative example provides an electrocatalytic oxidation method for organic wastewater, which is the same as Example 1 except that the gas-water volume ratio is 0.8:1.

[0100] Comparative Example 2

[0101] This comparative example provides an electrocatalytic oxidation method for organic wastewater, which is the same as Example 1 except that the gas-water volume ratio is 2.2:1.

[0102] The BOD5 and COD of the treated organic wastewater were measured to obtain the BOD5 / COD value. The results are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] In summary, the electrocatalytic oxidation method provided by the present invention is simple to operate. By simply controlling the parameters of the electrocatalytic oxidation process, the BOD5 / COD value of organic wastewater with COD ≥ 15000 mg / L can be increased to 0.6, making the organic wastewater biodegradable.

[0107] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for electrocatalytic oxidation of organic wastewater, characterized in that: The electrocatalytic oxidation method comprises the following steps: under aeration conditions, using a metal-supported catalyst to electrocatalytically oxidize and treat organic wastewater, wherein the residence time of the organic wastewater is 60-240 min and the gas-water volume ratio is (1-2):1; The organic wastewater has a COD concentration of 15000-25000 mg / L, BOD5 / COD≤0.1, a pH value of 6-8, and a chloride ion content of ≤5000 ppm; The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate; the metal oxide is a combination of CeO2 and TiO2; During the electrocatalytic oxidation, the distance between the anode plate and the cathode plate is 15-25 mm; The substrates of the anode plate and the cathode plate are independently titanium alloy, and the surface coatings are independently iridium-ruthenium alloy or iridium-tantalum alloy with a thickness of 8-12 μm.

2. The electrocatalytic oxidation method according to claim 1, characterized in that: The thickness of the anode plate is 1-2 mm.

3. The electrocatalytic oxidation method according to claim 1, characterized in that: The thickness of the cathode plate is 1-2 mm.

4. The electrocatalytic oxidation method according to claim 1, characterized in that: During the electrocatalytic oxidation treatment, the voltage between the plates is 28-32V.

5. The electrocatalytic oxidation method according to claim 1, characterized in that: The current density during the electrocatalytic oxidation treatment is 1000-1500A / m 2 .

6. The electrocatalytic oxidation method according to claim 1, characterized in that: The mass ratio of the metal oxide to the activated carbon substrate is 1:(30-40).

7. The electrocatalytic oxidation method according to claim 1, characterized in that: The mass ratio of CeO2 to TiO2 is (3-5):

1.

8. The electrocatalytic oxidation method according to claim 1, characterized in that: The preparation method of the metal supported catalyst comprises the following steps: An equal volume of a metal salt solution is impregnated into an activated carbon substrate, and then calcined after ultrasonic vibration to obtain the metal-supported catalyst; The metal salt solution contains metal oxides dissolved in a prescribed amount.

9. The electrocatalytic oxidation method according to claim 8, characterized in that: The activated carbon substrate may have a shape of a column, a strip or a sphere.

10. The electrocatalytic oxidation method according to claim 8, characterized in that: The calcination temperature is 450-500°C.

11. The electrocatalytic oxidation method according to claim 8, characterized in that: The calcination time is 3-5h.

12. The electrocatalytic oxidation method according to claim 1, characterized in that: The activated carbon substrate is an activated carbon substrate pretreated with acid.

13. The electrocatalytic oxidation method according to claim 12, characterized in that: The acid pretreatment comprises the following steps: soaking the activated carbon in nitric acid, washing it and then performing heat treatment to obtain the activated carbon substrate.

14. The electrocatalytic oxidation method according to claim 13, characterized in that: The mass concentration of the nitric acid is 60-65wt%.

15. The electrocatalytic oxidation method according to claim 13, characterized in that: The soaking time is 1-2h.

16. The electrocatalytic oxidation method according to claim 13, characterized in that: The temperature of the heat treatment is 200-240°C.

17. The electrocatalytic oxidation method according to claim 13, characterized in that: The heat treatment time is 1-2h.

18. The electrocatalytic oxidation method according to claim 1, characterized in that: The electrocatalytic oxidation method comprises the following steps: Under aeration conditions, metal-supported catalysts are used for electrocatalytic oxidation treatment of organic wastewater. The residence time of organic wastewater is 60-240 min, and the gas-water volume ratio is (1-2):

1. During electrocatalytic oxidation, the distance between the anode plate and the cathode plate is 15-25 mm, the inter-plate voltage is 28-32 V, and the current density is 1000-1500 A / m 2 The thickness of the anode plate and the cathode plate is 1-2 mm, the substrates of the anode plate and the cathode plate are independently titanium alloy, and the surface coatings are independently iridium-ruthenium alloy or iridium-tantalum alloy with a thickness of 8-12 μm; The metal-supported catalyst comprises an activated carbon substrate and a metal oxide supported on the activated carbon substrate, wherein the mass ratio of the metal oxide to the activated carbon substrate is 1:(30-40); the preparation method of the metal-supported catalyst comprises the following steps: An activated carbon substrate is impregnated with an equal volume of a metal salt solution, and then calcined at 450-500° C. for 3-5 hours after ultrasonic vibration to obtain the metal-supported catalyst; the metal salt solution contains a metal oxide dissolved in a formula amount; The preparation method of the activated carbon substrate comprises the following steps: soaking the activated carbon in nitric acid with a mass concentration of 60-65wt% for 1-2h, and heat treating at 200-240°C for 1-2h after washing to obtain the activated carbon substrate.

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