A method for degrading tetracycline antibiotics

Abstract

The invention discloses a method for degrading tetracycline antibiotics, which is characterized by placing a catalyst between the cathode and anode plates of an electrolytic cell, treating wastewater containing tetracycline antibiotics under the action of an electric field and microbubbles, and achieving degradation of the tetracycline antibiotics. The catalyst is prepared from tailings, and under the action of the electric field, microbubbles, and catalyst, the invention achieves electrochemical catalysis coordinated with microbubbles coupled to three-dimensional particle electrodes to degrade tetracycline antibiotics, significantly improving the degradation effect of the antibiotics, having excellent removal effect on antibiotics in the presence of high salt content, interfering ions, and a wide pH range, and having broad application prospects in the field of antibiotic removal.

Description

Technical Field

[0001] The invention belongs to the technical field of antibiotic degradation treatment, and particularly relates to a method for degrading tetracycline antibiotics. Background Art

[0002] Tetracycline antibiotics are among the earliest antibiotics used and widely adopted in medicine and veterinary medicine. However, their long-term and extensive use has also led to residual problems in the environment. Traditional biodegradation and physical treatment methods are inadequate for the degradation of tetracycline molecules, especially for some structurally more stable tetracyclines. The release of large amounts of tetracycline residues into the environment poses a potential threat to ecological and environmental safety.

[0003] Generally speaking, traditional techniques such as filtration, precipitation, coagulation, and gelation are ineffective in removing tetracyclines. Advanced oxidation processes (AOPs), such as sonolysis (ultrasound), Fenton-like processes, photocatalysis, and electrochemistry, are effective technologies for tetracycline degradation and detoxification in aqueous solutions. Electrochemical methods have shown great potential in environmental treatment. However, direct electrochemical degradation of tetracyclines also has limitations. These include a dependence of treatment efficiency on wastewater properties and limited selectivity for different molecules. To improve the effectiveness of electrochemical methods for antibiotic treatment, microbubbles, a novel three-phase interface preparation technology, are gaining increasing attention. Microbubbles can produce unique physical effects within a very small volume, such as strong electric fields and high-temperature zones. Studies have shown that microbubbles can successfully promote the removal of difficult-to-degrade wastewater pollutants, but their use alone cannot meet the requirements for efficient antibiotic degradation. Summary of the Invention

[0004] In response to the problems of the prior art, the present invention provides a method for degrading tetracycline antibiotics. A catalyst is placed between the cathode and anode plates of an electrolytic cell. Under the action of an electric field and microbubbles, wastewater containing tetracycline antibiotics is treated to achieve degradation of tetracycline antibiotics.

[0005] The catalyst is prepared by adding crushed tailings to a nitric acid solution with a concentration of 250-350 g / L, reacting at 150-250° C. for 3-5 hours, separating the solid and the liquid, adding a phosphoric acid solution with a mass concentration of 80-85% to the solid, reacting at 200-250° C. for 1-3 hours, separating the solid and the liquid, adding the solid to water at 85-95° C. and stirring for 1-2 hours, separating the solid and the liquid, drying the solid, dissolving the solid in 40-50% hydrofluoric acid, and then heating at 110° C. to 200° C. until completely dissolved. , sodium borohydride is added to the solution, with the mass ratio of solid to sodium borohydride being 20-100:1; cetyltrimethylammonium bromide or sodium lauryl sulfate is added after mixing, the mixture is transferred to a hydrothermal reaction tank, reacted at 20-70°C for 3-6 hours, solid-liquid separation is performed, the solid is ultrasonically cleaned with 70-80% ethanol, placed in an alcohol solution containing metal salt and graphene, 3-aminopropyltriethoxysilane is added, stirred evenly, transferred to a hydrothermal reaction tank, reacted at 180°C~300°C for 20~35 hours, cooled to room temperature, solid-liquid separation is performed, and the solid is washed and dried to obtain the product.

[0006] The mass ratio of the hexadecyltrimethylammonium bromide or sodium lauryl sulfate to sodium borohydride is 1:10-50.

[0007] The alcohol solution containing metal salt and graphene is an anhydrous ethanol or anhydrous methanol solution containing a mass volume concentration of 16-50% metal salt and a mass volume concentration of 0.1-1% graphene, wherein the metal salt is one or more of copper salt, manganese salt, titanium salt, iron salt, cobalt salt, nickel salt, and platinum salt.

[0008] The tailings are selected from copper tailings, phosphate tailings, lead-zinc tailings, antimony tailings and tin tailings.

[0009] Peroxydisulfate can also be added when treating wastewater, with 0.5-4 mmol of peroxydisulfate added per liter of wastewater.

[0010] The current density of the electric field is 5-35 mA / cm 2 The applied voltage is 3V-31V. Microbubbles are generated by a microbubble generator with an average bubble diameter of <200nm. The microbubble gas is one or more of air, pure oxygen, and ozone.

[0011] In the electrolyte solution, the electric field and aeration cause microbubbles to accumulate on the catalyst surface. These microbubbles locally exert a high electric field strength, promoting the reaction. Guided by the electric field, tetracycline antibiotic molecules are adsorbed onto the catalyst surface. The high-energy electrons and free radicals generated during the formation and collapse of the microbubbles can react with tetracycline antibiotic molecules adsorbed on the electrode surface. Due to the involvement of high-energy electrons and free radicals, tetracycline antibiotic molecules may undergo reactions such as oxidation, reduction, fragmentation, and depolymerization. These reactions may lead to structural changes and degradation of the tetracycline antibiotic molecules. Ultimately, degradation products can be released from the electrode surface through diffusion, convection, and electromigration in the electrolyte solution.

[0012] Advantages and technical effects of the present invention:

[0013] 1. Efficient degradation: Through the synergistic effect of electrochemical reaction, microbubbles and catalysts, tetracycline antibiotics can be quickly decomposed into harmless substances, improving degradation efficiency;

[0014] 2. Low energy consumption: The microbubble coupling reaction under electric field conditions has efficient mass transfer and heat transfer characteristics, which can increase the reaction rate and reduce energy consumption;

[0015] 3. High stability: The microbubble-coupled catalyst has high stability; the catalyst has a stable structure and can maintain a long service life. At the same time, the generation and stability of microbubbles can also improve the stability of the reaction;

[0016] 4. Reusable: The microbubble coupled catalyst can be used multiple times. By cleaning and regenerating the catalyst, the catalyst can be recycled and the waste of resources can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The results of the effects of different voltages on degradation are shown;

[0018] Figure 2 The results of the effects of different tetracycline concentrations on degradation are shown;

[0019] Figure 3 The results show the effects of different pH, normal aeration and microbubbles on the degradation of oxytetracycline. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 efforts are within the scope of protection of the present invention. Example 1

[0021] 1. Add the crushed antimony tailings to a 300g / L nitric acid solution, react at 200℃ for 4h, separate the solid and liquid, add 85% phosphoric acid solution to the solid, react at 250℃ for 2h, separate the solid and liquid, add the solid to 90℃ water and stir for 2h, separate the solid and liquid, dry the solid at 75℃ for 8h, dissolve the solid in 45% hydrofluoric acid, and then heat at 150℃ until completely dissolved, add sodium borohydride to the solution, the mass ratio of solid to sodium borohydride is 40:1; after mixing, add hexadecyltrimethylolpropane The mass ratio of ammonium bromide, hexadecyltrimethylammonium bromide and sodium borohydride is 1:20, and the mixture is transferred to a hydrothermal reaction tank and reacted at 50°C for 4 hours. The solid-liquid separation is performed, and the solid is ultrasonically cleaned with 75% ethanol, and then placed in anhydrous ethanol containing 20% ​​manganese nitrate and 0.5% graphene. 3-aminopropyltriethoxysilane (20 mg / L) is added, and after stirring evenly, the mixture is transferred to a hydrothermal reaction tank and reacted at 200°C for 25 hours. The mixture is cooled to room temperature, the solid-liquid separation is performed, and the solid is washed with distilled water several times and dried at 65°C for 24 hours to prepare the catalyst.

[0022] 2. A catalyst (0.2 g / L) was placed between the cathode and anode plates of the electrolytic cell. The cathode plate was a graphite electrode, and the anode plate was a foam nickel electrode. A tetracycline solution with a concentration of 50 mg / L and a pH of 7 was then introduced, and 1 mmol / L peroxydisulfate was added. The microbubble generator was turned on, and oxygen was introduced at a rate of 30 mL / min. Voltages of 5 V, 10 V, and 15 V were applied to the electrodes, respectively, to treat the wastewater containing tetracycline antibiotics. The results are shown in the table. Figure 1 ,It can be seen from the figure that within 120 min, the voltage increased from 5 V to 15 V, and the ,removal rates of tetracycline reached 80.74%, 90.57%, and 98.96%, respectively. Example 2

[0023] 1. Add the crushed phosphate tailings to a 250g / L nitric acid solution, react at 200°C for 4 hours, separate the solid and liquid, add a 85% mass concentration phosphoric acid solution to the solid, react at 250°C for 2 hours, separate the solid and liquid, add the solid to 90°C water and stir for 2 hours, separate the solid and liquid, dry the solid at 60°C for 12 hours, dissolve the solid in 48% hydrofluoric acid, and then heat at 150°C until completely dissolved. Add sodium borohydride to the solution with a mass ratio of solid to sodium borohydride of 50:1; after mixing, add hexadecyltrimethylammonium bromide The mass ratio of hexadecyltrimethylammonium bromide to sodium borohydride is 1:25, and the mixture is transferred to a hydrothermal reaction tank and reacted at 50°C for 4 hours. The solid-liquid separation is performed, and the solid is ultrasonically cleaned with 75% ethanol and then placed in anhydrous ethanol containing 30% ferric chloride, 15% ferrous chloride and 1% graphene. 3-aminopropyltriethoxysilane (30 mg / L) is added and stirred evenly. The mixture is transferred to a hydrothermal reaction tank and reacted at 200°C for 25 hours. The mixture is cooled to room temperature, and the solid-liquid separation is performed. The solid is washed with distilled water several times and dried at 70°C for 24 hours to obtain the catalyst.

[0024] 2. A catalyst (0.2 g / L) was placed between the cathode and anode plates of the electrolytic cell. The cathode plate was a graphite electrode, and the anode plate was a foam nickel electrode. 5 mg / L, 15 mg / L, and 30 mg / L tetracycline solutions were then introduced, respectively. 1 mmol / L peroxydisulfate was added, and the microbubble generator was turned on. Air was introduced at a rate of 50 mL / min. A voltage of 15 V was applied to the electrodes to treat the wastewater containing tetracycline antibiotics. The results are shown in the table. Figure 2 ,It can be seen from the figure that: when the initial concentrations were 5, 15 and 30 mg / L within 120 min, the TC removal rates reached 99.84%, 88.80% and 86.43%, respectively. Example 3

[0025] The crushed tin tailings were added to a 300 g / L nitric acid solution, reacted at 220 ° C for 5 hours, solid-liquid separation, 85% mass concentration of phosphoric acid solution was added to the solid, reacted at 250 ° C for 2 hours, solid-liquid separation, the solid was added to 90 ° C water and stirred for 2 hours, solid-liquid separation, the solid was dried at 60 ° C for 24 hours, the solid was dissolved in 40% hydrofluoric acid, and then heated at 150 ° C until completely dissolved, sodium borohydride was added to the solution, the mass ratio of solid to sodium borohydride was 25:1; after mixing, sodium lauryl sulfate and lauryl sulfate were added. The mass ratio of sodium nitrate:sodium borohydride is 1:30, the mixture is transferred to a hydrothermal reaction tank, reacted at 50°C for 4 hours, solid-liquid separation is performed, the solid is ultrasonically cleaned with 75% ethanol, and then placed in anhydrous ethanol containing 10% cobalt nitrate, 20% copper nitrate, 20% ferric chloride and 0.5% graphene, 3-aminopropyltriethoxysilane (50 mg / L) is added, stirred evenly, and then transferred to a hydrothermal reaction tank and reacted at 200°C for 25 hours. The reaction is cooled to room temperature, solid-liquid separation is performed, the solid is washed with distilled water several times, and dried at 60°C for 24 hours to obtain a catalyst;

[0026] 2. A catalyst (0.2 g / L) was placed between the cathode and anode plates of the electrolytic cell. The cathode plate was a graphite electrode and the anode plate was a foam nickel electrode. Oxytetracycline solutions (50 mg / L) with pH values ​​of 3, 5, 7, 9, and 11 were introduced, 1 mmol / L peroxydisulfate was added, the microbubble generator was turned on, ozone was introduced at a rate of 40 mL / min, and a voltage of 25 V was applied to the electrodes to treat the wastewater containing oxytetracycline antibiotics. The results are shown in the table. Figure 3 From the figure, it can be seen that in the process of ozone microbubbles participating, the degradation rate constant increased from 0.189 to 0.512 at pH 3.0-11.0, and the degradation rate constant of oxytetracycline at the optimal pH value (5.0) was 0.351min -1 .

[0027] At the same time, the ordinary aeration device was used as a control, and other conditions were the same as above. The results are shown in Figure 3 From the figure, it can be seen that during the conventional aeration process, the degradation rate constant increased from 0.0132 to 0.0155 min at pH 3.0-9.0. -1 , while it dropped to 0.0107 min at pH=11.0 -1 The degradation rate constant of oxytetracycline at the optimal pH value (9.0) is 0.0154min -1 .

Claims

1. A method for degrading tetracycline antibiotics, characterized in that: A catalyst is placed between the cathode and anode plates of the electrolytic cell, and peroxydisulfate is added. Under the action of an electric field and microbubbles, wastewater containing tetracycline antibiotics is treated to achieve degradation of tetracycline antibiotics. The catalyst is prepared by adding crushed tailings to a nitric acid solution with a concentration of 250-350 g / L, reacting at 150-250° C. for 3-5 hours, separating the solid and the liquid, adding a phosphoric acid solution with a mass concentration of 80-85% to the solid, reacting at 200-250° C. for 1-3 hours, separating the solid and the liquid, adding the solid to water at 85-95° C. and stirring for 1-2 hours, separating the solid and the liquid, drying the solid, dissolving the solid in 40-50% hydrofluoric acid, and then heating at 110° C. to 200° C. until completely dissolved. , adding sodium borohydride to the solution, with a mass ratio of solid to sodium borohydride of 20-100:1; after mixing, adding hexadecyltrimethylammonium bromide or sodium lauryl sulfate, transferring the mixture to a hydrothermal reaction tank, reacting at 20-70°C for 3-6 hours, solid-liquid separation, ultrasonically cleaning the solid with 70-80% ethanol, placing it in an alcohol solution containing metal salts and graphene, adding 3-aminopropyltriethoxysilane, stirring evenly, transferring it to a hydrothermal reaction tank, reacting at 180°C~300°C for 20~35 hours, cooling to room temperature, solid-liquid separation, and washing and drying the solid to obtain; The alcohol solution containing metal salt and graphene is an anhydrous ethanol or anhydrous methanol solution containing 16-50% by mass volume concentration of metal salt and 0.1-1% by mass volume concentration of graphene, wherein the metal salt is one or more of copper salt, manganese salt, titanium salt, iron salt, cobalt salt, nickel salt, and platinum salt, and the amount of 3-aminopropyltriethoxysilane added is 20-50 mg / L; The tailings are selected from copper tailings, phosphate tailings, lead-zinc tailings, antimony tailings, and tin tailings.

2. The method for degrading tetracycline antibiotics according to claim 1, characterized in that: The mass ratio of hexadecyltrimethylammonium bromide or sodium lauryl sulfate to sodium borohydride is 1:10~50.

3. The method for degrading tetracycline antibiotics according to claim 1, characterized in that: Microbubbles are generated by a microbubble generator, and the average diameter of the bubbles is <200nm.

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