Internal aeration type electro-Fenton device and method for treating antibiotic wastewater

Abstract

The present invention discloses an internal aeration electro-Fenton device and a method for treating antibiotic wastewater, which solves the technical problems of the existing electro-Fenton technology, such as the short existence time of free genes, low utilization rate, harsh pH conditions, high cost and poor reaction efficiency. The method comprises the following steps: step 1, preparation of iron oxyhydroxide-loaded clinoptilolite; step 2, installation of the electro-Fenton device, the device being a single-chamber reactor, an electrolytic cell made of organic glass, a carbon felt plate as the cathode, a titanium plate as the anode, the iron oxyhydroxide-loaded clinoptilolite described in step 1 as the catalyst, a copper wire as the conductor connected to the working power supply in the external circuit, and automatic recording of the voltage value every 15-30 minutes; step 3, starting the reactor. The present invention uses clinoptilolite as an adsorbent coupled with a carbon felt cathode, and the electro-Fenton reaction that occurs is a process of enrichment, degradation and regeneration, which is twice as efficient as the traditional electro-Fenton process and does not require extremely low pH conditions.

Description

Technical Field

[0001] The present invention relates to the fields of environmental antibiotic pollution, regeneration and electrochemistry, and in particular to a method for treating antibiotic wastewater using a cathode aerated iron oxyhydroxide-loaded clinoptilolite clean regeneration electro-Fenton process. Background Art

[0002] Antibiotics, chemical drugs used to kill or inhibit microorganisms, have made significant contributions to the treatment of bacterial infections and diseases. However, after entering the human body and organisms, antibiotics are not absorbed and are excreted as metabolites, causing environmental and water pollution. The impact of this drug contamination on human health continues to attract widespread attention. Therefore, it is imperative to develop effective methods for removing antibiotics. The main antibiotic residues in water fall into four categories: quinolones, macrolides, sulfonamides, and tetracyclines.

[0003] Currently, the treatment methods for antibiotics mainly include the following: biological methods (such as anaerobic biological methods, aerobic biological methods, etc.), physical methods (such as adsorption, membrane separation, flotation, etc.) and chemical methods (electro-Fenton, photocatalytic oxidation, ozone oxidation, etc.).

[0004] Electro-Fenton technology, due to its high efficiency, rapidity, and thoroughness, has been widely used in various fields of pollutant degradation. Compared to the traditional Fenton process, it generates H₂O₂ and hydroxyl radicals (•OH) through cathode aeration. •OH has a high oxidation potential and is non-selective, making it suitable for treating some difficult-to-degrade organic matter. However, •OH has a very short lifetime in water, typically 3-5 milliseconds, and its high energy consumption has hindered its development in water treatment. Improving the utilization of •OH, and thus the degradation efficiency of electro-Fenton technology, has become a key issue in this field. To address this technical challenge, extensive research has been conducted, including: modifying cathode materials; developing new electrode plates (from single electrodes to three-dimensional electrodes); developing catalysts (from homogeneous to heterogeneous catalysis); and integrating with other processes such as bio-electro-Fenton and biofuel cells. These measures have alleviated the energy consumption issue of electro-Fenton to some extent, but the demanding technical requirements for plate modification and the high cost of catalysts remain challenges. The low conversion rates of bio-electro-Fenton and microbial fuel cells currently prevent them from being put into practical production.

[0005] Homogeneous catalysts are widely used in traditional electro-Fenton processes. To prevent the formation of precipitates and sludge from free iron, which would affect removal efficiency, the reaction pH must be strictly controlled at around 3. After the reaction, the pH must be adjusted back to neutral to facilitate subsequent biological treatment. However, due to cost constraints, the homogeneous electro-Fenton process is only suitable for treating smaller volumes of wastewater, making it difficult to implement on a large scale in practical projects.

[0006] In order to improve the removal efficiency of ofloxacin and sulfamethoxazole and reduce their pollution in the environment, an improved electro-Fenton process was designed. Under the premise of considering economic costs, the electro-Fenton degradation efficiency was improved as much as possible so that it can be truly put into actual industrial production. Summary of the Invention

[0007] The purpose of the present invention is to provide an internal aeration electro-Fenton device and a method for treating antibiotic wastewater to solve the technical problems of the existing electro-Fenton technology, such as short existence time of free genes, low utilization rate, harsh pH conditions, high cost and poor reaction efficiency.

[0008] To achieve the above objectives, the present invention provides the following technical solutions:

[0009] The present invention provides an internal aeration type electro-Fenton device, comprising an electrolytic cell, an anode plate, a cathode plate, an aeration head, and an aeration pump;

[0010] Among them, the electrolytic cell is a single-chamber electrolytic cell, in which an anode plate and a cathode plate are arranged, the anode plate and the cathode plate are connected by a power supply, and a copper wire is used as a conductor in the external circuit to connect to the working power supply; the cathode plate is a cubic hollow structure, the interior of the hollow structure is provided with an aeration head and filled with iron oxide-loaded clinoptilolite, and the aeration head is connected to the aeration pump outside the electrolytic cell.

[0011] Furthermore, the method further comprises a rotor, and the reaction device is placed on a magnetic stirrer, and the reaction device and the rotor act together to stir the electrolyte.

[0012] Furthermore, the electrolytic cell is made of organic glass, with dimensions of 16cm×15cm×7cm, a thickness of 0.5cm, an effective volume of 1L, and a titanium electrode with dimensions of 6cm×10cm×0.2cm; the cathode plate is a carbon felt electrode with dimensions of 7cm×3cm×8cm, a wall thickness of 0.2cm, and a hollow interior.

[0013] Furthermore, the inner wall of the electrolytic cell is provided with a slot to facilitate the movement between the plates.

[0014] Furthermore, the power supply is provided by a DC regulated power supply with an adjustable voltage range of 0-15V and an adjustable current range of 0-2A.

[0015] Furthermore, the aeration pump is responsible for aerating the water, with an exhaust pressure of 0.02MP and an exhaust volume of 0.025m 3 •min -1 .

[0016] The present invention provides a method for treating antibiotic wastewater, characterized in that it is carried out using the internal aeration electro-Fenton device described in claims 1 to 6, and specifically comprises the following steps:

[0017] Step 1, preparation of iron oxyhydroxide-loaded clinoptilolite;

[0018] Step 2: Install an electro-Fenton device, wherein the cathode is a cubic hollow structure made of carbon felt, an aeration head is placed inside the hollow structure and filled with iron oxyhydroxide-loaded clinoptilolite, the aeration head and the iron oxyhydroxide-loaded clinoptilolite work together, and the electro-Fenton reaction occurring under coupled conditions is a process of enrichment, degradation, and regeneration, the anode is a metal titanium plate, the catalyst is the iron oxyhydroxide-loaded clinoptilolite described in step 1, and a copper wire is used as a conductor in the external circuit to connect to the working power supply, and the voltage value is automatically recorded every 15-30 minutes;

[0019] Step 3, start the reactor, add 10 mg / L ofloxacin solution and 10 mg / L sulfamethoxazole solution, respectively, and add 150 mg of FeSO4. The aeration position adopts the internal position, and the loading FeOOH zeolite is added in an amount of 20 g. After starting, the concentrations of the ofloxacin solution and sulfamethoxazole in the reactor are recorded every ten minutes;

[0020] Step 4: When the concentrations of ofloxacin and sulfamethoxazole drop to 0.5 mg / L, disconnect the power supply to stop the reaction, add ofloxacin solution and sulfamethoxazole solution to 10 mg / L respectively, and continue the reaction. If the difference between the two reaction times does not exceed five minutes, it means that the startup is successful. After the startup is successful, replace the ofloxacin solution and sulfamethoxazole solution with 20 mg / L and continue the reaction.

[0021] Furthermore, in step 1, the preparation of the iron oxyhydroxide-loaded clinoptilolite comprises the following sub-steps:

[0022] Step 1.1. Weigh 0.5-1 mm particle size clinoptilolite into a beaker and rinse repeatedly with deionized water to remove dust from the surface of the zeolite. Then, soak it in 80% acetone solution and shake it in an ultrasonic cleaner for 120 minutes to remove organic impurities on the surface. Finally, rinse it again with deionized water and dry it in a 60°C oven for later use.

[0023] Step 1.2, prepare 1 mol•L -1 NaOH solution and 0.5 mol•L -1 1L of FeCl3 solution each;

[0024] Step 1.3: Add 100 mL of the prepared FeCl3 solution to a water bath at 90-100°C, then add 10 g of clinoptilolite and stir continuously with a magnetic stirrer for 20 min. Drain with a glass rod and slowly pour in 100 mL of the prepared NaOH solution. Stir slowly with a glass rod to ensure full contact between the clinoptilolite and the solution until the solution evaporates to dryness.

[0025] Step 1.4: Place the clinoptilolite in an oven at 105°C for 8 hours, then place it in a muffle furnace and calcine it for 2 hours at 400°C. After taking it out, rinse it with deionized water and finally place it in an oven at 105°C for drying.

[0026] Furthermore, in step 3, the current density of the reactor is 10 mA·m -2 , reaction time 40min, pH is neutral, and the plate distance is 3cm.

[0027] Based on the above technical solution, the embodiments of the present invention can produce at least the following technical effects:

[0028] (1) The internal aeration electro-Fenton device and the method for treating antibiotic wastewater provided by the present invention use clinoptilolite as an adsorbent coupled with a carbon felt cathode. The electro-Fenton reaction is a process of enrichment, degradation, and regeneration. The treatment efficiency is twice as high as that of the traditional electro-Fenton process, and extremely low pH conditions are not required. The adsorption of ofloxacin and sulfamethoxazole near the cathode is increased, and there is no need to modify the electrode plate. Clinoptilolite is easy to replace and inexpensive, making it suitable for actual industrial production.

[0029] (2) The internal aeration electro-Fenton device and method for treating antibiotic wastewater provided by the present invention have an aeration position located at the bottom of the carbon felt cube. Dissolved oxygen in the interior generates •OH through the electro-Fenton reaction, which can immediately degrade ofloxacin and sulfamethoxazole adsorbed by the clinoptilolite. This avoids the problem that •OH cannot react quickly with ofloxacin due to its short existence time, greatly improving the degradation efficiency. At the same time, the water flow generated by the aeration stirs the interior of the carbon felt, causing some of the zeolites adsorbed with ofloxacin and sulfamethoxazole to be disturbed internally and cleaned by the action of •OH, thus achieving the purpose of recycling.

[0030] (3) The method for treating antibiotic wastewater provided by the present invention loads FeOOH onto clinoptilolite and activated carbon, thereby avoiding the problems of iron sludge pollution and recovery difficulties generated by homogeneous catalysts, increasing the reaction pH range while reducing operating costs and facilitating subsequent biological treatment.

[0031] (4) The present invention provides a method for treating antibiotic wastewater. The reaction equipment has low cost and a short operating cycle. After multiple cycles of continuous operation, the degradation efficiency of ofloxacin and sulfamethoxazole remains close to 100%, and the filled adsorption material can be cleanly regenerated, with the effluent concentration far below the emission standard. An electro-Fenton reactor with green clean regeneration function for degrading ofloxacin and sulfamethoxazole wastewater has been successfully designed. Compared with the traditional electro-Fenton reactor, it has excellent performance in treating ofloxacin and sulfamethoxazole wastewater, and the equipment and materials are low-priced, providing a new idea for achieving green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0033] Figure 1 Schematic diagram of the structure of the internal exposure type electro-Fenton device of the present invention;

[0034] Figure 2 It is a schematic diagram of the method for treating antibiotic wastewater of the present invention;

[0035] In the figure: 1. Electrolytic cell; 2. Anode plate; 3. Cathode plate; 4. Aeration head; 5. Aeration pump; 6. Rotor. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] See also Figure 1 、 Figure 2 , an internal aeration type electro-Fenton device, characterized in that it includes an electrolytic cell 1, an anode plate 2, a cathode plate 3, an aeration head 4, and an aeration pump 5;

[0038] The electrolytic cell 1 is a single-chamber electrolytic cell, in which an anode plate 2 and a cathode plate 3 are provided. The anode plate 2 and the cathode plate 3 are connected by a power supply provided by a DC regulated power supply with an adjustable voltage range of 0-15V and an adjustable current range of 0-2A. A copper wire is used as a conductor in the external circuit to connect to the working power supply; the cathode plate 3 is a cubic hollow structure, and an aeration head 4 is provided inside the hollow structure and filled with iron oxyhydroxide-loaded clinoptilolite. The aeration head 4 is connected to the aeration pump 5 outside the electrolytic cell 1, and the aeration pump 5 is responsible for aerating the water. The exhaust pressure is 0.02MP and the exhaust volume is 0.025m 3 •min -1 .

[0039] In a specific embodiment, a rotor 6 is further included. The reaction device is placed on a magnetic stirrer, and the reaction device and the rotor 6 work together to stir the electrolyte.

[0040] In a specific embodiment, the electrolytic cell 1 is an electrolytic cell made of organic glass, with dimensions of 16cm×15cm×7cm, a thickness of 0.5cm, and an effective volume of 1L. The inner wall of the electrolytic cell 1 is provided with a slot to facilitate the movement between the plates; the anode plate is a titanium electrode with dimensions of 6cm×10cm×0.2cm; the cathode plate is a carbon felt electrode with dimensions of 7cm×3cm×8cm, a wall thickness of 0.2cm, and a hollow interior.

[0041] The present invention provides a method for treating ofloxacin and sulfamethoxazole mixed wastewater by using a cathode aerated iron oxyhydroxide-loaded clinoptilolite clean regeneration electro-Fenton process, which is prepared according to the following steps:

[0042] Step 1: prepare iron oxyhydroxide-loaded clinoptilolite.

[0043] Step 1.1. Weigh 1 mm particle size clinoptilolite into a beaker and rinse repeatedly with deionized water to remove dust from the surface of the zeolite. Then, soak it in 80% acetone solution and shake it in an ultrasonic cleaner for 120 minutes to remove organic impurities on the surface. Finally, rinse it again with deionized water and dry it in a 60°C oven for later use.

[0044] Step 1.2, prepare 1 mol•L -1 NaOH solution and 0.5 mol•L -1 1L of FeCl3 solution each.

[0045] Step 1.3: Add 100 ml of the prepared FeCl3 solution to a water bath at 95°C, then add 10 g of clinoptilolite and stir continuously with a magnetic stirrer for 20 min. Drain with a glass rod and slowly pour in 100 ml of the prepared NaOH solution. Stir slowly with a glass rod to ensure full contact between the clinoptilolite and the solution until the solution evaporates to dryness.

[0046] Step 1.4: Place the zeolite in an oven at 105°C for 8 hours, then place it in a muffle furnace and calcine it for 2 hours. After taking it out, rinse it with deionized water and finally place it in an oven at 105°C for drying.

[0047] Step 2, electro-Fenton reactor configuration (such as Figure 1 As shown): The equipment is a single-chamber reactor, with an electrolytic cell made of organic glass, with dimensions of 16cm×15cm×7cm, a thickness of 0.5cm, and an effective volume of 1L. The anode is a titanium electrode with dimensions of 6cm×10cm×0.2cm; the cathode electrode is a carbon felt electrode with dimensions of 7cm×3cm×8cm, a wall thickness of 0.2cm, and a hollow interior. The inner wall of the electrolytic cell is provided with a slot to facilitate the movement between the plates; the power supply is provided by a DC regulated power supply with an adjustable voltage range of 0-15V and an adjustable current range of 0-2A; the reaction device is placed on a magnetic stirrer to stir the electrolyte. The aeration pump is responsible for aerating the water, with an exhaust pressure of 0.02MP and an exhaust volume of 0.025m 3 •min -1 ;

[0048] The cathode is a cubic hollow structure made of carbon felt. An aeration head is placed inside the hollow structure and filled with iron oxyhydroxide-loaded clinoptilolite. The aeration head and the iron oxyhydroxide-loaded clinoptilolite work together. The electro-Fenton reaction that occurs under coupled conditions is a process of enrichment, degradation, and regeneration. The anode is a metal titanium plate, and the catalyst is the iron oxyhydroxide-loaded clinoptilolite described in step 1. Copper wire is used as a conductor in the external circuit to connect to the working power supply, and the voltage value is automatically recorded every 15-30 minutes.

[0049] Step 3: Start the reactor, add 10 mg / L ofloxacin and sulfamethoxazole solution respectively into the reaction chamber, add 150 mg of FeSO4, and set the current density to 10 mA·m -2 , reaction time 40min, pH is neutral, plate spacing is 3cm, aeration position is internal, loading FeOOH zeolite dosage is 20g, and the concentrations of ofloxacin and sulfamethoxazole in the reactor are recorded every ten minutes after startup.

[0050] Step 4: When their concentration drops to 0.5 mg / L, disconnect the power supply to stop the reaction, add the two solutions to 10 mg / L respectively and continue the reaction. If the difference between the two reaction times does not exceed five minutes, it means the startup is successful. After the startup is successful, replace the two solutions with 20 mg / L and continue the reaction.

[0051] The results of this experiment showed that under optimal experimental conditions, within a reaction time of 40 minutes, the removal rates of ofloxacin and TOC reached 94% and 82%, respectively; the removal rates of sulfamethoxazole and TOC reached 97% and 78%, respectively. After five runs, the FeOOH-loaded zeolite catalyst achieved removal rates of 75.42% for ofloxacin and 52.28% for TOC; and 65.4% for sulfamethoxazole and 57.3% for TOC. The loaded material exhibited excellent stability, with a catalyst weight difference of 0.77 g.

[0052] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An internal aeration type electro-Fenton device, characterized in that: It includes an electrolytic cell (1), an anode plate (2), a cathode plate (3), an aeration head (4), and an aeration pump (5); The electrolytic cell (1) is a single-chamber electrolytic cell, in which an anode plate (2) and a cathode plate (3) are provided, the anode plate (2) and the cathode plate (3) are connected via a power supply, and a copper wire is used as a conductor in an external circuit to connect to a working power supply; the cathode plate (3) is a cubic hollow structure, an aeration head (4) is provided inside the hollow structure and filled with iron oxide-carrying clinoptilolite, and the aeration head (4) is connected to an aeration pump (5) outside the electrolytic cell (1); the electrolytic cell (1) is made of organic glass, and a slot is provided on the inner wall to facilitate the movement of the electrode plate; the cathode plate is a carbon felt electrode; The device also includes a rotor (6), and the reaction device is placed on the magnetic stirrer, and the reaction device and the rotor (6) act together to stir the electrolyte.

2. The internal aeration type electro-Fenton device according to claim 1, characterized in that: The electrolytic cell (1) has a size of 16 cm × 15 cm × 7 cm, a thickness of 0.5 cm, an effective volume of 1 L, and a titanium electrode with a size of 6 cm × 10 cm × 0.2 cm for the anode plate and a size of 7 cm × 3 cm × 8 cm for the cathode plate, with a wall thickness of 0.2 cm.

3. The internal aeration electro-Fenton device according to claim 1, characterized in that: The power supply is provided by a DC regulated power supply, the voltage adjustable range is 0-15V, and the current adjustable range is 0-2A.

4. The internal aeration type electro-Fenton device according to claim 1, characterized in that: The aeration pump (5) is responsible for aerating the water, with an exhaust pressure of 0.02MP and an exhaust volume of 0.025m 3 •min -1 .

5. A method for treating antibiotic wastewater, characterized in that: The method is carried out using the internal aeration electro-Fenton device according to any one of claims 1 to 4, and specifically comprises the following steps: Step 1, preparing iron oxyhydroxide-loaded clinoptilolite; Step 2, installing an electro-Fenton device, wherein the cathode is a cubic hollow structure made of carbon felt, an aeration head (4) is placed inside the hollow structure and filled with iron hydroxide-loaded clinoptilolite, the aeration head (4) and the iron hydroxide-loaded clinoptilolite act together, and the electro-Fenton reaction occurring under coupled conditions is a process of enrichment, degradation, and regeneration, the anode is a metal titanium plate, the catalyst is the iron hydroxide-loaded clinoptilolite described in step 1, and a copper wire is used as a conductor in the external circuit to connect to the working power supply, and the voltage value is automatically recorded every 15-30 minutes; Step 3: Start the reactor, add 10 mg / L ofloxacin solution and 10 mg / L sulfamethoxazole solution, respectively, add 150 mg of FeSO4, use internal aeration, add 20 g of FeOOH-loaded zeolite, and record the concentrations of ofloxacin and sulfamethoxazole in the reactor every ten minutes after startup; Step 4: When the concentrations of ofloxacin and sulfamethoxazole drop to 0.5 mg / L, disconnect the power supply to stop the reaction, add ofloxacin solution and sulfamethoxazole solution to 10 mg / L respectively, and continue the reaction. If the difference between the two reaction times does not exceed five minutes, it means that the startup is successful. After the startup is successful, replace the ofloxacin solution and sulfamethoxazole solution with 20 mg / L and continue the reaction.

6. The method for treating antibiotic wastewater according to claim 5, wherein: In step 1, the preparation of the iron oxyhydroxide-loaded clinoptilolite comprises the following sub-steps: Step 1.

1. Weigh 0.5-1 mm particle size clinoptilolite into a beaker and rinse repeatedly with deionized water to remove dust from the surface of the zeolite. Then, soak it in 80% acetone solution and shake it in an ultrasonic cleaner for 120 minutes to remove organic impurities on the surface. Finally, rinse it again with deionized water and dry it in a 60°C oven for later use. Step 1.2, prepare 1 mol•L -1 NaOH solution and 0.5 mol•L -1 1L of FeCl3 solution each; Step 1.3: Add 100 mL of the prepared FeCl3 solution to a water bath at 90-100°C, then add 10 g of clinoptilolite and stir continuously with a magnetic stirrer for 20 min. Drain with a glass rod and slowly pour in 100 mL of the prepared NaOH solution. Stir slowly with a glass rod to ensure full contact between the clinoptilolite and the solution until the solution evaporates to dryness. Step 1.4: Place the clinoptilolite in an oven at 105°C for 8 hours, then place it in a muffle furnace and calcine it for 2 hours at 400°C. After taking it out, rinse it with deionized water and finally place it in an oven at 105°C for drying.

7. The method for treating antibiotic wastewater according to claim 5, wherein: In step 3, the current density of the reactor is 10 mA·m -2 , reaction time 40min, pH is neutral, and the plate distance is 3cm.

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