Heterogeneous electro-Fenton reaction device for high-concentration organic wastewater treatment

Abstract

The invention belongs to the technical field of environmental protection, and provides a heterogeneous electro-Fenton reaction device for high-concentration organic wastewater treatment. The equipment core comprises a cathode, an anode, a gas diffusion chamber, a reaction tank and the like; the cathode adopts a heterogeneous catalyst and a gas diffusion type oxygen supply electrode structure, is tightly attached to two sides of the gas diffusion chamber, is arranged in parallel and opposite to the anode, and is fixedly connected with the anode to form an electrode group module, the electrode group module is placed in a reaction tank with an insulating shell, and the cathode and the anode are respectively connected with a power supply to carry out electro-Fenton degradation on the high-concentration organic wastewater; a heterogeneous catalysis mode is selected, the pH application range of the Fenton reaction can be widened, and secondary pollution is avoided; an oxygen supply mode of a gas diffusion electrode is adopted, so that the mass transfer efficiency of oxygen in a reaction system can be improved; the electro-Fenton reaction device is used for treating high-concentration organic wastewater, and is high in treatment efficiency, low in energy consumption, environment-friendly and low in operation and maintenance cost.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment. Background Art

[0002] At present, the water pollution situation in my country is still severe. Among them, industrial wastewater contains a large amount of persistent, bioaccumulative, carcinogenic and teratogenic organic pollutants with complex composition, high concentration, high toxicity and difficulty in biological treatment, which poses a serious threat to human health and ecological balance. Traditional water treatment technologies such as physical adsorption and biochemical treatment technologies usually face the shortcomings of low treatment efficiency, poor mineralization ability and easy secondary pollution when dealing with such persistent and difficult to degrade pollutants. Fenton technology is an efficient oxidation removal technology for organic pollutants. It uses hydrogen peroxide (H2O2) as a reactant and removes Fe 2+ Catalytic decomposition of H2O2 produces highly oxidizing ·OH to achieve the degradation and mineralization of pollutants. However, traditional Fenton technology usually faces the disadvantages of narrow pH application range, difficult catalyst recovery and large amount of iron sludge, and it consumes a large amount of H2O2 and Fe 2+ Reagents, and concentrated H2O2 has the potential safety hazard of explosion during storage and transportation, which has become a potential risk of Fenton technology in actual operation. In recent years, the coupling of traditional Fenton technology with electrocatalytic O2 reduction to produce H2O2 technology to construct electro-Fenton technology has received widespread attention in the field of water treatment due to its unique advantages. Electro-Fenton technology only uses green O2 and H2O as reactants, and drives the reaction through renewable electric energy. H2O2 is continuously produced in situ by cathode reduction of O2, which avoids the problem of H2O2 addition in traditional Fenton technology and effectively reduces the consumption of chemical reagents. Subsequently, the in-situ generated H2O2 is activated and decomposed by the bifunctional heterogeneous cathode catalyst to produce highly oxidizing active oxygen free radicals, solving the shortcomings of the traditional Fenton technology with a narrow pH range and the production of iron mud. In the electro-Fenton reaction process, the oxygen mass transfer efficiency and the selection of cathode catalysts are crucial, which can directly affect the yield of active oxygen free radicals and the treatment effect of wastewater. It is very necessary to effectively improve the oxygen mass transfer efficiency and current utilization rate in electro-Fenton technology and increase the yield of active oxygen free radicals for the industrial application of this technology.

[0003] The present invention provides a heterogeneous electro-Fenton reaction device for treating high-concentration organic wastewater. The cathode adopts a bifunctional heterogeneous catalyst and a gas diffusion oxygen supply method to improve the mass transfer efficiency of oxygen and the yield of active oxygen free radicals, and combines with the oxidation effect of the anode to improve the current efficiency, enhance the wastewater treatment effect and reduce the operating cost. Summary of the invention

[0004] The purpose of the present invention is to provide a heterogeneous electro-Fenton reaction device for treating high-concentration organic wastewater.

[0005] To achieve the above object, the technical solution of the present invention is as follows: A heterogeneous electro-Fenton reaction device for treating high-concentration organic wastewater, comprising a cathode, an anode, a reaction tank, a power supply, a gas diffusion chamber, etc.; Among them, the cathode and the anode are arranged in parallel and opposite positions, fixedly connected to form an electrode group module, and the module is placed inside a reaction tank with an insulating shell. The cathode and the anode in the electrode group are respectively connected to the power supply. The cathode adopts a heterogeneous catalyst and a gas diffusion type oxygen supply electrode structure. The cathode end is closely attached to both sides of the gas diffusion chamber. Oxygen in the gas diffusion chamber can directly pass through the cathode, and under the action of the heterogeneous catalyst on the cathode, H2O2 is in-situ generated through a 2e - oxygen reduction reaction, and then the in-situ generated H2O2 is reduced to generate reactive oxygen free radicals (such as: ·OH, O2 ·- , 1 O2) for the degradation of pollutants. The edge connection between the cathode and the gas diffusion chamber is separated and fixed by a waterproof insulating pad. The gas diffusion chamber is provided with an air inlet and an air outlet, and an air pump can be externally connected to control the gas flow according to requirements. The internal space of the reaction tank is a reaction zone, and electro-Fenton degradation reaction of the wastewater is carried out in the reaction zone. The reaction tank is provided with a water inlet and a water outlet, and a water pump can be externally connected to control the wastewater flow according to requirements.

[0006] Further, the cathode adopts a gas diffusion type oxygen supply electrode structure, and the electrode is composed of a gas diffusion layer and a catalytic layer; the gas diffusion layer can select a variety of conductive carriers, including, but not limited to, metal meshes, carbon papers, carbon cloths, carbon felts, etc.; the catalytic layer selects a coating material loaded with a "bifunctional" catalyst.

[0007] Further, the "bifunctional" catalyst has two different catalytic active sites. One of the catalytic active sites can electrocatalytically reduce O2 to generate H2O2, and then the electro-synthesized H2O2 is in-situ decomposed into reactive oxygen free radicals (such as: ·OH, O2· - , 1 O2) for the treatment of high-concentration organic wastewater.

[0008] Further, the "bifunctional" catalyst includes, but is not limited to, heteroatom-doped carbon catalysts, carbon catalysts loaded with metal nanoparticles, carbon catalysts loaded with metal oxide nanoparticles, carbon catalysts loaded with metal single atoms, or carbon catalysts loaded with metal clusters, etc.

[0009] Further, the anode materials include, but are not limited to, carbon electrodes (such as graphite, carbon paper, carbon cloth, carbon felt, etc.), titanium-based tin antimony oxide coated electrodes, titanium-based ruthenium iridium oxide coated electrodes, titanium-based lead dioxide electrodes, platinum electrodes, and boron-doped diamond electrodes.

[0010] Furthermore, the distance between the cathode and the anode is fixed and consistent, and the range of the plate distance is less than 10 cm.

[0011] Furthermore, the gas diffusion chamber adopts a hollow cavity structure, and a diversion channel with a circuitous path can be constructed inside according to actual treatment requirements. This can not only increase the supply pressure of the gas and extend the residence time of the gas, but also support the cathode and prevent the deformation of the cathode electrode plate, thus extending the service life of the electrode. The gas diffusion chamber can introduce oxygen, air, or a mixture of oxygen and air according to requirements. The gas diffusion chamber supports bilateral synchronous supply of reaction gas to the cathode, enabling efficient utilization of the reaction device space and small floor area. The thickness of the gas diffusion chamber is preferably 0.1 - 10 cm.

[0012] Furthermore, the modular design of the device allows for flexible adjustment of the number of combined units of the gas diffusion chamber and the electrode group, and the optimized number of units is 1 - 20 groups.

[0013] Furthermore, during the electro-Fenton reaction process, power is supplied by a power source, and the power supply mode can be set to a constant voltage mode or a constant current mode. In the constant voltage mode, the voltage applied to the cathode is -0.1 to -10 V, preferably -0.2 to -2 V. In the constant current mode, the applied current density is 0.1 - 200 mA cm -2 , preferably 0.5 - 50 mA cm -2 .

[0014] The beneficial effects of the present invention are as follows: The preparation method of the electro-Fenton reaction device for treating high-concentration organic wastewater is simple, low-cost, easy to operate, small in floor area, and long in service life; it can in-situ generate a sufficient amount of reactive oxygen free radicals, avoiding the problems of a large amount of Fenton reagent addition and a narrow pH application range; it adopts a gas diffusion type oxygen supply electrode structure, which can not only enhance the mass transfer efficiency of oxygen and provide sufficient O2 for the electro-Fenton reaction, but also play a stirring role and enhance the diffusion and mass transfer of pollutants; using the electro-Fenton reaction device to treat wastewater has good treatment effect, high current efficiency, low energy consumption, and low operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 A front view structural diagram of an electro-Fenton reaction device for wastewater treatment related to the present invention is shown; Figure 2 A surface morphology diagram of the bifunctional heterogeneous cathode catalyst related to the present invention is shown; Figure 3 Shows the long-term operational stability diagram of the removal of sulfamethoxazole by the bifunctional heterogeneous cathode catalyst involved in the present invention. Detailed implementation manners

[0016] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0017] The present invention provides a heterogeneous electro-Fenton reaction device for treating high-concentration organic wastewater, and its basic idea is: As shown in the figure, a heterogeneous electro-Fenton reaction device for treating high-concentration organic wastewater includes a cathode 1, an anode 2, a reaction tank 3, a power supply 4, a gas diffusion chamber 5, a reaction zone 6, etc.; where: the cathode 1 and the anode 2 are arranged in parallel and opposite positions, fixedly connected to form an electrode group module, and this module is placed in the reaction tank 3 with an insulating shell. The cathode 1 and the anode 2 in the electrode group are respectively connected to the power supply 4. The cathode 1 is closely attached to both sides of the gas diffusion chamber 5. Oxygen in the gas diffusion chamber 5 can directly pass through the cathode 1 and, under the action of the heterogeneous catalyst on the cathode, generate H2O2 in situ through a 2e - oxygen reduction reaction. Immediately, the in-situ generated H2O2 is reduced to generate reactive oxygen free radicals (such as: ·OH, O2· - , 1 O2) for the degradation of pollutants. The edge connection between the cathode 1 and the gas diffusion chamber 5 is separated and fixed by a waterproof insulating pad. The gas diffusion chamber 5 is provided with an air inlet and an air outlet, and an air pump can be externally connected to control the gas flow according to requirements. The internal space of the reaction tank 3 is the reaction zone 6, and the electro-Fenton degradation reaction of the wastewater is carried out in the reaction zone 6. The reaction tank 3 is provided with a water inlet and a water outlet, and a water pump can be externally connected to the water inlet to control the wastewater flow according to requirements.

[0018] Furthermore, the cathode 1 adopts a gas diffusion type oxygen supply electrode structure, and this electrode is composed of a gas diffusion layer and a catalytic layer; the gas diffusion layer selects a conductive carrier, including, but not limited to, metal mesh, carbon paper, carbon cloth, carbon felt, etc.; the catalytic layer selects a coating material loaded with a "bifunctional" catalyst;

[0019] Furthermore, the said "bifunctional" catalyst has two different catalytic active sites. One of the catalytic active sites can electrocatalytically reduce O2 to generate H2O2. Immediately, the electro-synthesized H2O2 is in-situ decomposed into reactive oxygen free radicals on the other catalytic active site (such as: ·OH, O2· - , 1O2) for the treatment of high-concentration organic wastewater.

[0020] Further, the "bifunctional" catalyst includes, but is not limited to, heteroatom-doped carbon catalysts, carbon catalysts loaded with metal nanoparticles, carbon catalysts loaded with metal oxide nanoparticles, carbon catalysts loaded with single metal atoms, or carbon catalysts loaded with metal clusters, etc.

[0021] Further, the anode 2 material includes, but is not limited to, carbon electrodes (such as graphite, carbon paper, carbon cloth, and carbon felt, etc.), titanium-based tin-antimony oxide coated electrodes, titanium-based ruthenium-iridium oxide coated electrodes, titanium-based lead dioxide electrodes, platinum electrodes, and boron-doped diamond electrodes.

[0022] Further, the distance between the cathode 1 and the anode 2 is fixed and consistent, and the range of the plate distance is less than 10 cm.

[0023] Further, the gas diffusion chamber adopts a hollow cavity structure, and a diversion channel with a circuitous path can be constructed inside according to actual treatment requirements. Oxygen, air, or a mixture of oxygen and air can be introduced into the gas diffusion chamber according to requirements. The gas diffusion chamber supports the synchronous supply of reaction gases to the cathode on both sides, the reaction device space can be efficiently utilized, and the floor area is small. The thickness of the gas diffusion chamber is preferably 0.1 - 10 cm.

[0024] Further, the number of units of the gas diffusion chamber 5 and the electrode group can be set according to requirements, and the optimized number of units is 1 - 20 groups.

[0025] Further, during the electro-Fenton reaction process, power is supplied by the power supply 4, and the power supply mode can be set to a constant voltage mode or a constant current mode. In the constant voltage mode, the voltage applied to the cathode 1 is -0.1 to -10 V, preferably -0.2 to -2 V. In the constant current mode, the applied current density is 0.1 - 200 mA cm -2 , preferably 0.5 - 50 mA cm -2 .

[0026] The following will further illustrate an electro-Fenton reaction device for wastewater treatment according to the present invention in the form of specific embodiments.

[0027] Example 1: A hollow porous carbon sphere / carbon cloth electrode with a size of 5 cm × 5 cm is used as the cathode 1, and a titanium-based tin-antimony oxide coated electrode of the same size is used as the anode 2. The electrode distance is fixed at 2 cm. The electrodes are placed in an electro-Fenton reaction tank 3 with a slightly larger size. The number of units in the electro-Fenton reaction zone 6 is 3 groups. The cathode 1 and the anode 2 are externally connected to the power supply 4 with copper wires, and the thickness of the gas diffusion chamber 5 is 2 cm. For a concentration of 20 mg L -1Perform electro-Fenton treatment on organic pollutants such as phenol, ciprofloxacin, sulfamethoxazole, and 4-chlorophenol. Add 50 mM of the electrolyte sodium sulfate, and introduce oxygen into the gas diffusion chamber 5 during the reaction process. Under the constant voltage mode with a voltage of -0.6 V applied to the cathode 1 by the power supply 4, perform electro-Fenton treatment on the above organic wastewater; Test and analyze the organic sewage before and after treatment. The results show that: after 1 hour of electro-Fenton treatment, the degradation rates of phenol, ciprofloxacin, sulfamethoxazole, and 4-chlorophenol are 99%, 98%, 99%, and 99% respectively; after 3 hours of electro-Fenton treatment, the TOC removal rates are 80%, 74%, 78%, and 75% respectively.

[0028] Example 2: In this example, the electro-Fenton reaction device is the same as that in Example 1, and treat the secondary effluent of coking wastewater with an initial COD value of 244 mg / L -1 and an initial TOC value of 59 mg / L -1 , and the initial pH is 7.2. The operating conditions are the same as those in Example 1; Analyze and test the secondary effluent of coking wastewater after 4 hours of electro-Fenton treatment. The results show that the COD value of the secondary effluent of coking wastewater decreases from 244 mg / L -1 to 51 mg / L -1 , and the TOC value decreases from 59 mg / L -1 to 17 mg / L -1 .

[0029] The above-described embodiments only represent the implementation manners of the present invention, but should not be construed as limiting the scope of the present invention patent. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A heterogeneous electro-Fenton reaction device for treating high-concentration organic wastewater, characterized in that: A heterogeneous electro-Fenton reaction device for treating high-concentration organic wastewater, the core components of which include a cathode, an anode, a gas diffusion chamber, a reaction tank, a power supply, etc.; the cathode and the anode are arranged in parallel and opposite positions, fixedly connected to form an electrode group module, and the module is placed inside a reaction tank with an insulating shell. The cathode and the anode in the electrode group are respectively connected to the power supply. The cathode adopts a heterogeneous catalyst and a gas diffusion type oxygen supply electrode structure. The cathode end is closely attached to both sides of the gas diffusion chamber. Oxygen in the gas diffusion chamber can directly pass through the cathode and, under the action of the heterogeneous catalyst on the cathode, generate H2O2 in situ through a 2e - oxygen reduction reaction, and then the in-situ generated H2O2 is reduced to generate reactive oxygen free radicals (such as: ·OH, O2· - , 1 O2) for the degradation of pollutants. The edge connection between the cathode and the gas diffusion chamber is separated and fixed by a waterproof insulating pad. The internal space of the reaction tank is the reaction zone, and the electro-Fenton degradation reaction of the wastewater is carried out in the reaction zone.

2. The heterogeneous electro-Fenton reaction device for high-concentration organic wastewater treatment according to claim 1, wherein The cathode adopts a gas diffusion type oxygen supply electrode structure, which is composed of a gas diffusion layer and a catalytic layer; various conductive carriers can be selected for the gas diffusion layer, including, but not limited to, metal mesh, carbon paper, carbon cloth, carbon felt, etc.; the catalytic layer selects a coating material loaded with a "dual-functional" heterogeneous catalyst. The described "bifunctional" heterogeneous catalyst has two different catalytic active sites. One of the catalytic active sites can electrocatalytically reduce O2 to generate H2O2, and then the electro-synthesized H2O2 is in-situ decomposed at the other catalytic active site to generate reactive oxygen species (such as ·OH, O2· - , 1 O2) for the treatment of high-concentration wastewater; The "dual-functional" catalyst includes, but is not limited to, heteroatom-doped carbon catalysts, carbon catalysts loaded with metal nanoparticles, carbon catalysts loaded with metal oxide nanoparticles, carbon catalysts loaded with metal single atoms, or carbon catalysts loaded with metal clusters, etc.

3. The heterogeneous electro-Fenton reaction device for high-concentration organic wastewater treatment according to claim 1, wherein, The anode materials include, but are not limited to, carbon electrodes (such as graphite, carbon paper, carbon cloth, carbon felt, etc.), titanium-based tin-antimony oxide coated electrodes, titanium-based ruthenium-iridium oxide coated electrodes, titanium-based lead dioxide electrodes, platinum electrodes, and boron-doped diamond electrodes.

4. The heterogeneous electro-Fenton reaction device for high-concentration organic wastewater treatment according to claim 1, wherein The gas diffusion chamber adopts a hollow cavity structure, and a diversion channel with a circuitous path can be constructed inside according to actual treatment requirements. This structure supports synchronous supply of reaction gas to the cathode from both sides, and pure oxygen, air, or a mixed gas of the two can be selectively introduced. The thickness of the gas diffusion chamber is designed in the range of 0.1 - 10 cm.

5. The heterogeneous electro-Fenton reaction device for high-concentration organic wastewater treatment according to claim 1, characterized in that, The modular design of the device allows flexible adjustment of the number of combined units of the gas diffusion chamber and the electrode group, and the optimized number of units is 1 - 20 groups.

6. The heterogeneous electro-Fenton reaction device for high-concentration organic wastewater treatment according to claim 1, characterized in that, During the electro-Fenton reaction process, power is supplied by a power source, and the power supply mode can be set to a constant voltage mode or a constant current mode. In the constant voltage mode, the voltage applied to the cathode is -0.1 to -10 V, preferably -0.2 to -2 V. In the constant current mode, the applied current density is 0.1 to 200 mA cm -2 , preferably 0.5 to 50 mA cm -2 .

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