An electro-Fenton system with an electro-responsive cyclic catalytic electrode and a water treatment method thereof

Abstract

The present invention provides an electro-Fenton system of an electro-responsive cyclic catalytic electrode and a water treatment method thereof, which relates to the technical field of wastewater treatment and includes a hydrogen peroxide-producing cathode, a cyclic catalytic cathode, an electrochemical reaction cell, an anode, a power supply and an air pump. The hydrogen peroxide cathode, the cyclic catalytic cathode and the anode are located inside the electrochemical reaction cell. The electrochemical reaction cell is used for wastewater treatment, the air pump is used for aerating the electrochemical reaction cell, and the power supply is used for power supply. By in-situ producing hydrogen peroxide at the hydrogen peroxide-producing cathode, and using the cyclic catalytic cathode as electro-Fenton after being electrified to continuously activate hydrogen peroxide to generate reactive oxygen species, and by the anode undergoing an oxidation reaction, the present invention has the advantages of not consuming reagents and catalysts, high catalytic efficiency, in-situ cyclic catalysis, not generating waste sludge, and long service life of the electrode. In water treatment, it realizes green oxidation, degrades organic pollutants in sewage, and has the characteristics of low energy consumption, low cost and easy automation control.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly to an electro-Fenton system with an electro-responsive cyclic catalytic electrode and a water treatment method thereof. Background Art

[0002] The electro-Fenton process generates Fenton reagents (such as hydroxyl radicals) through electrolysis. These reagents have very strong redox capabilities and can effectively degrade organic substances and decompose them into non-toxic inorganic substances. During electrolysis, an iron electrode and a noble metal electrode (usually platinum) are placed in wastewater at a specific pH value, and electrolysis is carried out for a certain period of time to generate Fenton reagents;

[0003] The application of the traditional electro-Fenton process in wastewater treatment has the following deficiencies: large consumption of reagents, low treatment efficiency, difficulty in regenerating and recycling the catalyst, generation of a large amount of waste sludge, and relatively high operating costs. The cost-effectiveness of the electro-Fenton process depends on the activation of H2O2 and the regeneration of the catalyst. The activation of H2O2 to generate reactive oxygen species mainly occurs at the Fe(II) active sites, and the conversion of Fe(III) to Fe(II) for the regeneration of the Fe(II) catalytic sites is the key rate-limiting step in all heterogeneous Fenton processes. However, it is still difficult and challenging to convert Fe(III) to Fe(II) at the cathode. Developing an efficient catalyst cycle and water treatment efficiency for the electro-Fenton process is an urgent problem to be solved. Therefore, the present invention proposes an electro-Fenton system with an electro-responsive cyclic catalytic electrode and a water treatment method thereof to solve the problems existing in the prior art. Summary of the Invention

[0004] In view of the above problems, the present invention proposes an electro-Fenton system with an electro-responsive cyclic catalytic electrode and a water treatment method thereof. The electro-Fenton system with the electro-responsive cyclic catalytic electrode and the water treatment method generate hydrogen peroxide in situ at the hydrogen peroxide cathode, act as electro-Fenton after being energized through the cyclic catalytic cathode, continuously activate hydrogen peroxide to generate reactive oxygen species, and undergo an oxidation reaction at the anode. It has the advantages of not consuming reagents and catalysts, high catalytic efficiency, in-situ cyclic catalysis, not generating waste sludge, and long service life of the electrode.

[0005] To achieve the object of the present invention, the present invention is realized through the following technical solutions: An electro-Fenton system with an electro-responsive cyclic catalytic electrode, comprising a hydrogen peroxide cathode, a cyclic catalytic cathode, an electrochemical reaction cell, an anode, a power supply, and an air pump. The hydrogen peroxide cathode, the cyclic catalytic cathode, and the anode are located inside the electrochemical reaction cell;

[0006] The electro-chemical reaction cell is used for wastewater treatment. The air pump is used to aerate the electro-chemical reaction cell. The power supply is used for power supply. The hydrogen peroxide-producing cathode is used for in-situ production of hydrogen peroxide. After being electrified, the cyclic catalytic cathode is used to continuously activate hydrogen peroxide to generate reactive oxygen species. The anode is used for oxidation reaction.

[0007] A further improvement lies in that: the cyclic catalytic cathode is an electrode with electro-responsive redox characteristics. Ferrocene metal-organic framework is in-situ prepared on the current collector plate by a one-step hydrothermal method. The current collector plate includes one of titanium plate, titanium mesh, nickel mesh, nickel foam, stainless steel mesh, titanium foam, and stainless steel foam.

[0008] A further improvement lies in that: the preparation method of the electrode with electro-responsive redox characteristics includes the following steps:

[0009] Mix ferrocene organic ligand and metal salt evenly according to a molar ratio of 1:1, and dissolve them in water and DMF organic solvent;

[0010] Put it together with a current collector into a hydrothermal reaction kettle and react under the condition of 80-150 °C;

[0011] After the reaction, wash with water and dry to obtain an electrode with electro-responsive redox characteristics.

[0012] A further improvement lies in that: the hydrogen peroxide-producing cathode is one of graphite, carbon felt, carbon paper, and carbon nanotube electrode.

[0013] A further improvement lies in that: the anode is one of ruthenium-iridium-titanium electrode, tin-antimony electrode, tin dioxide electrode, Ti4O7 electrode, and BDD electrode.

[0014] A further improvement lies in that: the power supply is a multi-mode power supply, and the power supply is connected to the hydrogen peroxide-producing cathode, the cyclic catalytic cathode, the anode, and the air pump for power supply and controlling the current mode.

[0015] A further improvement lies in that: a micro-porous inert material tank is arranged inside the electro-chemical reaction cell, and the micro-porous inert material tank is located below the hydrogen peroxide-producing cathode and the cyclic catalytic cathode. The output end of the air pump is connected to the micro-porous inert material tank.

[0016] A further improvement lies in that: the micro-porous inert material tank is one of ceramics, mica, and carbon materials.

[0017] A further improvement lies in that: the distance between the hydrogen peroxide-producing cathode and the cyclic catalytic cathode is 0.1 cm - 0.8 cm.

[0018] A water treatment method for an electro-responsive cyclic catalytic electrode electro-Fenton system includes the following steps:

[0019] Aerate the electrochemical reaction cell through an air pump;

[0020] Apply a voltage. After power-on, the sewage enters the electrochemical reaction cell through the inlet;

[0021] Flow through the hydrogen peroxide-producing cathode, the cyclic catalytic cathode, and the anode once;

[0022] The organic pollutants in the wastewater are degraded, discharged from the outlet, and clean water is obtained;

[0023] The cyclic catalytic cathode is regenerated in-situ, continuously producing reactive oxygen species.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. In the present invention, hydrogen peroxide is produced in-situ by the hydrogen peroxide-producing cathode. After power-on, the cyclic catalytic cathode continuously activates hydrogen peroxide to produce reactive oxygen species, and an oxidation reaction occurs at the anode. It has the advantages of not consuming chemicals and catalysts, high catalytic efficiency, in-situ cyclic catalysis, no generation of waste sludge, and long service life of the electrodes. In water treatment, it realizes green oxidation, degrades organic pollutants in sewage, and has the characteristics of low energy consumption, low cost, and easy automation control.

[0026] 2. In the present invention, the metallocene organic ligand and the metal salt are dissolved in water and DMF organic solvent, and reacted with a current collector to obtain a catalyst as the cyclic catalytic cathode. The catalyst grows in-situ on the porous foam metal, has good electrical conductivity, can increase the effective catalytic area, is conducive to long-term stable existence, shows obvious electrical response characteristics, can efficiently activate hydrogen peroxide to produce reactive oxygen while the catalyst is regenerated in-situ under electric drive, realizing electrically responsive continuous cyclic catalysis.

[0027] 3. The present invention does not require the addition of chemical agents, adopts a multi-mode power supply, synchronously controls the hydrogen peroxide-producing cathode, the cyclic catalytic cathode, and the air pump under different modes, applies a multi-mode micro-gradient voltage under the condition of sharing one anode, realizes electrically driven catalysis of hydrogen peroxide to produce reactive oxygen, synchronously and synergistically removes pollutants efficiently, and has lower energy consumption. Brief Description of the Drawings

[0028] Figure 1 It is the main view of the system of the present invention;

[0029] Figure 2 It is the schematic diagram of the cyclic catalytic electrode of the present invention;

[0030] Figure 3 It is the schematic diagram of the two-dimensional nanosheet array structure of the present invention;

[0031] Figure 4 It is the SEM image of the traditional metal oxide electrode;

[0032] Figure 5X-ray diffraction characterization diagram of the cyclic catalytic electrode of the present invention;

[0033] Figure 6 Electrical response characteristic diagram of the cyclic catalytic electrode of the present invention;

[0034] Figure 7 Water treatment effect diagram of the present invention (taking ciprofloxacin antibiotic wastewater as an example);

[0035] Figure 8 Schematic diagram of the removal efficiency of pollutants at different flow rates of the present invention. Detailed implementation manners

[0036] To deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation to the protection scope of the present invention.

[0037] Embodiment 1

[0038] According to Figure 1 、 2 As shown in Figures 3, 4, 5, 6, 7, 8, this embodiment proposes an electro-Fenton system with an electrically responsive cyclic catalytic electrode, which includes a hydrogen peroxide-producing cathode, a cyclic catalytic cathode, an electrochemical reaction cell, an anode, a power supply and an air pump. The hydrogen peroxide cathode, the cyclic catalytic cathode and the anode are located inside the electrochemical reaction cell;

[0039] The electrochemical reaction cell is used for wastewater treatment. The air pump is used to aerate the electrochemical reaction cell. The power supply is used for power supply. The hydrogen peroxide-producing cathode is used for in-situ production of hydrogen peroxide. After being energized, the cyclic catalytic cathode is used to continuously activate hydrogen peroxide to generate reactive oxygen species. The anode is used for oxidation reaction.

[0040] The cyclic catalytic cathode is an electrode with electrically responsive redox characteristics. Ferrocene metal-organic framework is in-situ prepared on the current collector plate by a one-step hydrothermal method. The current collector plate includes one of titanium plate, titanium mesh, nickel mesh, nickel foam, stainless steel mesh, titanium foam, and stainless steel foam.

[0041] The preparation method of the electrode with electrically responsive redox characteristics includes the following steps: mixing ferrocene organic ligand and metal salt in a molar ratio of 1:1 and dissolving them in water and DMF organic solvent; putting them together with a current collector into a hydrothermal reaction kettle and reacting under the condition of 80-150 °C; after the reaction, washing with water and drying to obtain the electrode with electrically responsive redox characteristics.

[0042] The hydrogen peroxide-producing cathode is one of graphite, carbon felt, carbon paper, and carbon nanotube electrode. The anode is one of ruthenium-iridium-titanium electrode, tin-antimony electrode, tin dioxide electrode, Ti4O7 electrode, and BDD electrode.

[0043] The power supply is a multi-standard power supply, and the power supply is connected to the hydrogen peroxide-producing cathode, the circulating catalytic cathode, the anode and the air pump, and is used for power supply and current mode control.

[0044] A microporous inert material tank is arranged inside the electro-chemical reaction cell, and the microporous inert material tank is located below the hydrogen peroxide-producing cathode and the circulating catalytic cathode. The output end of the air pump is connected to the microporous inert material tank. The microporous inert material tank is one of ceramics, mica and carbon materials and is used for aeration.

[0045] The distance between the hydrogen peroxide-producing cathode and the circulating catalytic cathode is 0.1 cm - 0.8 cm.

[0046] A water treatment method for an electro-Fenton system with an electro-responsive circulating catalytic electrode includes the following steps:

[0047] Aerate the electro-chemical reaction cell through the air pump;

[0048] Apply voltage. After power-on, the sewage enters the electro-chemical reaction cell through the water inlet;

[0049] Flow through the hydrogen peroxide-producing cathode, the circulating catalytic cathode and the anode once;

[0050] The organic pollutants in the wastewater are degraded and discharged from the outlet to obtain clean water;

[0051] The circulating catalytic cathode is regenerated in-situ to continuously produce reactive oxygen species.

[0052] Example Two

[0053] According to Figure 1 、 2 、3, 4, 5, 6, 7, 8, this example proposes an electro-Fenton system with an electro-responsive circulating catalytic electrode and its water treatment method, including.

[0054] An electro-responsive circulating catalyst: The innovative features of this catalyst: It has the properties of conductivity, electro-responsiveness, and catalyzing H2O2, and can achieve electro-driven redox cycle catalysis. In-situ preparation method: Dissolve the metallocene organic ligand (iron, cobalt, nickel, vanadium) and the metal (iron, cobalt, nickel, vanadium) salt in a molar ratio of 1:1.2 into a mixed solvent of water and N,N-dimethylformamide, and put it into a reaction kettle together with a current collector, and react at 80 - 150 °C for 24 - 48 h. After the reaction, wash with water and dry to obtain the catalyst. This catalyst grows in-situ on the porous foam metal (iron, cobalt, nickel, vanadium) and has good electrical conductivity. As Figure 2 shown, the catalyst presents a uniform two-dimensional nanosheet array structure ( Figure 3 ), compared with the general electrode structure ( Figure 4) can increase the effective catalytic area. Through X-ray diffraction characterization ( Figure 5 ), the catalyst exhibits high crystallinity and purity, which is beneficial for long-term stable existence. Due to the innovative use of metallocene organic ligands to synthesize the metal-organic framework structure, which has obvious redox characteristics, the catalytic electrode shows obvious electrical response characteristics, with obvious oxidation peaks and reduction peaks appearing in the cyclic voltammetry curve ( Figure 6 ), while traditional foam metal electrodes do not show oxidation peaks or reduction peaks in electrochemical tests. This catalyst can efficiently activate H2O2 to generate reactive oxygen species and simultaneously realize in-situ regeneration of the catalyst under electric drive, achieving continuous cyclic catalysis with electrical response.

[0055] Table 1: Effects of reaction temperature and reaction time on the purity of the catalyst

[0056]

[0057]

[0058] The electro-Fenton system of the electro-responsive cyclic catalytic electrode: hydrogen peroxide-producing cathode, cyclic catalytic cathode, electrochemical reaction cell, anode, power supply, and air pump. The innovative use of the electro-responsive cyclic catalytic electrode to activate H2O2 in the electro-Fenton process eliminates the need to add chemical agents and catalysts, continuously activates hydrogen peroxide to generate reactive oxygen species, realizes green oxidation, and degrades organic pollutants in wastewater. The traditional electro-Fenton reaction uses a three-electrode system with the addition of chemicals, such as using a carbon cathode to produce hydrogen peroxide and adding FeCl2 to catalyze H2O2 or adding a powder catalyst to activate hydrogen peroxide. The cost of adding chemicals is high, and in addition, a large amount of iron sludge waste needs to be treated, and the catalyst cannot be regenerated. The system of the present invention adopts a dual-cathode design. One cathode is used to produce hydrogen peroxide, and its material is a porous carbon-based catalytic material. The other is an electro-responsive cyclic catalytic electrode, and its material is a foam homogeneous metal evolved after the reaction of an organic ligand metallocene. To ensure the utilization efficiency of in-situ produced hydrogen peroxide, the distance between the two cathode plates is 0.1 - 0.8 cm. The produced hydrogen peroxide is activated into reactive oxygen species by the other electro-responsive cyclic catalytic electrode. In-situ production of H2O2 and activation without adding any chemicals can achieve chemical agent savings and high-efficiency wastewater treatment. The innovative use of a dual-cathode sharing one anode system, with the power supply controlling the current mode, and the two cathodes placed close to each other, is conducive to the rapid diffusion of the produced H2O2 to the surface of the catalytic electrode, improving the treatment efficiency. The coupling anodic oxidation design is adopted. In this system, the anode uses an electrode with oxidation ability to simultaneously oxidize pollutants in the wastewater. This electrode system can realize self-repair of the electrocatalyst and continuously catalyze the oxidation and degradation of pollutants in the long term.

[0059] Water treatment application of an electro-responsive cyclic catalyst electrode system: Using this system for water treatment: No chemical agents need to be added. A multi-mode collaborative control mode power supply system is adopted to synchronously control the catalytic device and the air pump under different modes. Under a shared anode, a multi-mode micro-gradient voltage is applied to realize electro-driven catalysis to generate active oxygen from H2O2 and synchronously and efficiently remove pollutants.

[0060] Specific steps: Assemble according to the electrode system. Through the multi-mode collaborative control mode power supply system, control the two cathodes to work under a micro-gradient voltage. After power-on, aerate near the double cathodes through an air pump. The aeration uses a microporous inert material (such as ceramics, mica, carbon materials, etc.) tank for aeration to effectively buffer the bubble impulse, generate uniform and gentle micro-nano bubbles near the double cathodes, effectively promote mass transfer, promote the generation of H2O2 and effectively migrate it to the cyclic catalytic cathode to carry out the Fenton reaction. The influent adopts a gentle influent method to avoid impact on the electrodes. The sewage flows through the electrochemical reaction cell at a flux of 50 - 100L m -2 h -1 The sewage first passes through the hydrogen peroxide-producing cathode, and then on the cyclic catalytic cathode, H2O2 is rapidly activated to generate a large amount of highly active oxygen species, which oxidize and degrade the organic matter in the sewage. Finally, the sewage passes through the anode, and the pollutants are further oxidized, and clean water is obtained at the outlet. The cyclic catalytic cathode is regenerated in-situ and continuously produces active oxygen species. The energy consumption per ton of water treatment of this system is only 0.08 kWh.

[0061] Table of energy consumption per ton of water treatment

[0062] Different voltage conditions Energy consumption (kwh / t) 1V 0.11 1.5V 0.08 2V 0.12

[0063] In the present invention, hydrogen peroxide is produced in-situ by the hydrogen peroxide-producing cathode, and after power-on, the cyclic catalytic cathode acts as an electro-Fenton to continuously activate hydrogen peroxide to generate active oxygen species. Through the oxidation reaction occurring at the anode, it has the advantages of not consuming agents and catalysts, high catalytic efficiency, in-situ cyclic catalysis, not generating waste sludge, and long electrode service life. In water treatment, it realizes green oxidation, degrades organic pollutants in sewage, and has the characteristics of low energy consumption, low cost, and easy automation control. Moreover, the metallocene organic ligand and metal salt are dissolved in water and DMF organic solvent, and reacted together with a current collector to obtain a catalyst as the cyclic catalytic cathode. This catalyst grows in-situ on the porous foam metal, has good electrical conductivity, can increase the effective catalytic area, is conducive to long-term stable existence, exhibits obvious electro-responsive characteristics, can efficiently activate hydrogen peroxide to generate active oxygen, and at the same time, under the action of electric drive, the catalyst is regenerated in-situ, realizing electro-responsive continuous cyclic catalysis. At the same time, the present invention does not need to add chemical agents, adopts a multi-mode power supply, synchronously controls the hydrogen peroxide-producing cathode, cyclic catalytic cathode, and air pump under different modes, applies a multi-mode micro-gradient voltage under a shared anode, realizes electro-driven catalysis to generate active oxygen from hydrogen peroxide, and synchronously and efficiently removes pollutants with lower energy consumption.

[0064] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. An electro-Fenton system with an electro-responsive cyclic catalytic electrode, comprising a hydrogen peroxide-producing cathode, a cyclic catalytic cathode, an electrochemical reaction cell, an anode, a power supply and an air pump, characterized in that: The hydrogen peroxide cathode, the circulating catalytic cathode and the anode are located inside the electrochemical reaction cell; the electrochemical reaction cell is used for wastewater treatment, the air pump is used to aerate the electrochemical reaction cell, the power supply is used for power supply, the hydrogen peroxide-producing cathode is used for in-situ production of hydrogen peroxide, the circulating catalytic cathode is used to continuously activate hydrogen peroxide to generate reactive oxygen species after being energized, and the anode is used for oxidation reaction; The circulating catalytic cathode is an electrode with electro-responsive redox characteristics, and ferrocene metal-organic framework is in-situ prepared on the current collector plate by a one-step hydrothermal method. The current collector plate includes one of titanium plate, titanium mesh, nickel mesh, nickel foam, stainless steel mesh, titanium foam, and stainless steel foam; A preparation method of an electrode with electro-responsive redox characteristics includes the following steps: mixing a metallocene organic ligand and a transition metal salt in a molar ratio of 1:1, dissolving them in a mixed solvent of water and dimethylformamide (DMF) (1:1); putting a current collector together into a hydrothermal reaction kettle and reacting under the condition of 8**0-150°C; after the reaction, washing with water and drying to obtain an electrode with electro-responsive redox characteristics; The distance between the hydrogen peroxide-producing cathode and the circulating catalytic cathode is 0.1 cm - 0.8 cm.

2. The electro-Fenton system of an electro-responsive cyclic catalytic electrode according to claim 1, characterized in that: The hydrogen peroxide-producing cathode is one of graphite, carbon felt, carbon paper, and carbon nanotube electrode.

3. The electro-Fenton system of an electro-responsive cyclic catalytic electrode according to claim 1, characterized in that: The anode is one of ruthenium-iridium-titanium electrode, tin-antimony electrode, tin dioxide electrode, titanium suboxide electrode, and boron-doped diamond electrode.

4. The electro-Fenton system of an electro-responsive cyclic catalytic electrode according to claim 1, characterized in that: The power supply is a multi-mode power supply, and the power supply is connected to the hydrogen peroxide-producing cathode, the circulating catalytic cathode, the anode and the air pump for power supply and controlling the current mode.

5. The electro-Fenton system of an electro-responsive cyclic catalytic electrode according to claim 1, characterized in that: A microporous inert material tank is arranged inside the electrochemical reaction cell, and the microporous inert material tank is located directly below the hydrogen peroxide-producing cathode and the circulating catalytic cathode. The output end of the air pump is connected to the microporous inert material tank for improving the mass transfer of reactants.

6. The electro-Fenton system of an electro-responsive cyclic catalytic electrode according to claim 5, wherein: The microporous inert material tank is one of ceramics, mica, and carbon materials.

7. A water treatment method for an electro-Fenton system of an electro-responsive cyclic catalytic electrode, applying the electro-responsive cyclic catalytic electrode electro-Fenton system described in any one of the above claims 1-6, characterized in that, It includes the following steps: Aerate the electrochemical reaction cell through the air pump; apply voltage. After being energized, the sewage enters the electrochemical reaction cell through the water inlet; flows through the hydrogen peroxide-producing cathode, the circulating catalytic cathode and the anode in sequence; the organic pollutants in the wastewater are degraded and discharged from the outlet to obtain clean water; the circulating catalytic cathode is regenerated in-situ and continuously generates reactive oxygen species.

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