Method for degrading tetracycline and oxytetracycline by producing treating fluid through electro-catalysis water oxidation

Abstract

The invention discloses a method for degrading tetracycline and oxytetracycline through an electrocatalytic water oxidation production treatment liquid, which comprises the following steps: (1) preparation of the electrocatalytic water oxidation treatment liquid: constructing an electrocatalytic environment and an electrochemical double cell, separating an anode and a cathode through a nafion membrane only allowing protons to pass through, enabling the anode to be a carbon-based material loaded with a water oxidation material, and preparing the electrocatalytic water oxidation treatment liquid through a Nafion membrane only allowing protons to pass through; the cathode is a graphite sheet, and the electrolyte is a mixed solution of potassium carbonate and potassium bicarbonate. Then carrying out an electro-catalysis water oxidation reaction to obtain a treatment solution; and (2) degrading tetracycline antibiotic pollutants by using the electro-catalytic water oxidation treatment liquid: taking out the electro-catalytic water oxidation treatment liquid in the step (1) at normal temperature and pressure, putting the electro-catalytic water oxidation treatment liquid into a water sample containing tetracycline or oxytetracycline, and stirring, so that tetracycline and oxytetracycline can be oxidized and degraded without adding any chemical reagent and other operations.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalytic water oxidation, and in particular relates to a method for degrading tetracycline and oxytetracycline by producing a treatment liquid through electrocatalytic water oxidation. Background Art

[0002] Tetracycline antibiotics (TCs) are the most widely used antibiotics, and they are also the most widely used antibiotics in my country's livestock and poultry industry. The environmental pollution and ecotoxicological effects of antibiotics have become one of the major environmental problems facing my country and the world. After tetracycline wastewater produced during the production and use of industries such as medical and animal husbandry enters the natural world, it will be enriched through the food chain, causing organisms to develop antibiotic resistance. Efficient and clean treatment technology is urgently needed to effectively remove it. At present, the treatment and disposal methods for tetracycline antibiotic wastewater mainly include biological methods, adsorption methods, membrane treatment methods, electrochemical methods, and advanced oxidation methods. However, due to the antibacterial and bactericidal properties of antibiotics in biological methods, and the relatively stable molecular structure of tetracycline antibiotics, microorganisms usually show weak degradation of them, and plant methods take too long and are not thorough. The adsorption method can separate and transfer pollutants from the aqueous phase, but it does not essentially eliminate and reduce the harm of pollutants. The problem with membrane treatment methods is membrane pollution. The intercepted pollution leads to decreased efficiency of membrane pore blockage, and frequent membrane cleaning and replacement bring additional workload and cost. The electrochemical method has a large unit power consumption, high requirements for equipment, and the anode plate is easily "passivated". Advanced oxidation technology is a new and popular pretreatment method. Its principle is mainly to generate hydroxyl radicals (·OH) with strong oxidizing ability or activate persulfate to generate sulfate radicals (SO4 - ·) to oxidize pollutants to achieve efficient removal. Pollutants are treated by activating hydrogen peroxide to produce hydroxyl radicals. It is green and pollution-free, and does not introduce other ions. The main methods are photocatalysis, transition metal activation, and electrocatalysis. Among them, photocatalysis requires strong light irradiation and needs to solve the problem of light transmittance. The actual application has high environmental requirements and is difficult to popularize. When hydrogen peroxide is activated by adding transition metals, metal ion leaching will occur in actual application, which is easy to cause secondary pollution. In addition, hydrogen peroxide is explosive during transportation and storage, which poses a great safety hazard. Many hazardous incidents have been reported. In-situ production of hydrogen peroxide by electrocatalysis is a method with great application potential. Hydrogen peroxide is prepared on site to degrade pollutants, which avoids the problems caused by the transportation and storage of hydrogen peroxide. At present, there are two methods: electrocatalytic oxygen reduction and electrocatalytic water oxidation. Among them, electrocatalytic oxygen reduction is very dependent on oxygen exposure equipment, which is troublesome to use and has poor production efficiency. It cannot meet the treatment needs of high-concentration hydrogen peroxide and requires additional activation of hydrogen peroxide to ensure sufficient degradation effect. Electrocatalytic water oxidation does not require additional equipment and can prepare hydroperoxide anions (HO2 -) and hydrogen peroxide (H2O2) to degrade tetracycline and oxytetracycline without activation, which is difficult to achieve with the above-mentioned advanced oxidation methods. In addition, the technology can continuously produce a mixed treatment solution under low voltage conditions, which can be used for ex situ treatment, providing great convenience for practical applications. Summary of the invention

[0003] In view of the urgent need for treating tetracycline antibiotic pollution in aquaculture water, the present invention aims to provide a method for degrading tetracycline and oxytetracycline by producing a treatment liquid through electrocatalytic water oxidation. The method of the present invention has the advantages of simple equipment, convenient operation, low cost, and environmental friendliness.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A method for degrading tetracycline and oxytetracycline by electrocatalytic water oxidation production treatment liquid, the method comprising the following steps:

[0006] (1) Preparation of electrocatalytic water oxidation treatment solution:

[0007] The electrocatalytic environment is set up, and the electrochemical double cell is separated by a nafion membrane that only allows protons to pass through. The anode is a carbon-based material loaded with water oxidation materials, the cathode is a graphite sheet, and the electrolyte is a mixture of 0-3.5M potassium carbonate and 0-0.5M potassium bicarbonate. Then, the electrocatalytic water oxidation reaction is carried out at 2.0-4Vversus RHE for 30-60min to obtain a treatment solution containing hydrogen peroxide and hydroperoxide anions;

[0008] (2) The electrocatalytic water oxidation treatment liquid degrades tetracycline antibiotic pollutants:

[0009] At room temperature and pressure, 5 ml of the electrocatalytic water oxidation treatment liquid of step (1) is taken out and placed in a water sample containing tetracycline or oxytetracycline and stirred without adding any chemical reagents or other operations to obtain solution 1; wherein the hydroperoxide anions and hydrogen peroxide in the treatment liquid in solution 1 have strong oxidizing properties and can directly oxidize and degrade tetracycline and oxytetracycline.

[0010] Preferably, the anode of the electrocatalytic environment in step (1) is a carbon-based material loaded with water oxidation materials such as bismuth antimonate, copper tungstate, bismuth tungstate, zinc tungstate, antimony tungstate, zinc gallium oxide, etc., and the cathode is a graphite sheet.

[0011] Preferably, the electrolyte in the electrocatalytic environment in step (1) is a mixture of 0-3.5M potassium carbonate and 0-0.5M potassium bicarbonate.

[0012] Preferably, the electrocatalytic water oxidation reaction time in step (1) is 30 to 60 minutes.

[0013] Preferably, the device in step (1) is an electrochemical dual cell, the anode and cathode are separated by a nafion membrane that only allows protons to pass through, and the electrocatalytic water oxidation voltage is 2.0-4V versus RHE.

[0014] Preferably, the concentration of tetracycline or oxytetracycline in the wastewater of step (2) is 1 ppm-50 ppm.

[0015] Preferably, the volume of the treatment liquid in step (2) is 0-1 / 30 of the volume of the wastewater.

[0016] Preferably, in step (2), the stirring speed is set at 300 rpm and the stirring time is 1 hour.

[0017] Preferably, the tetracycline pollutants treated in step (2) include tetracycline, oxytetracycline and chlortetracycline.

[0018] Compared with the prior art, this application has the following advantages:

[0019] (1) Using H2O, which is widely available in the environment, as raw material, only cheap carbonates and bicarbonates are needed as electrolytes to produce hydrogen peroxide anions and hydrogen peroxide treatment fluid at low voltage. It has the advantages of rapid on-site preparation and low green energy consumption;

[0020] (2) The reaction can occur at normal temperature and pressure, and can degrade organic pollutants efficiently and quickly;

[0021] (3) The mixed treatment liquid can be used conveniently and can be further adapted to the polluted environment, thus having great application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the performance diagram of the mixed treatment solution degrading 50ml of tetracycline of different concentrations;

[0023] Figure 2 The performance diagram of the mixed treatment solution degrading 50 ml of oxytetracycline with different concentrations;

[0024] Figure 3 This is the performance diagram of the mixed treatment liquid degrading 50ml of 25ppm tetracycline in aquaculture water;

[0025] Figure 4 This is the performance diagram of the mixed treatment solution degrading 50ml of 25ppm oxytetracycline in aquaculture water;

[0026] Figure 5 This is the performance diagram of 100mM hydrogen peroxide degrading tetracycline in water;

[0027] Figure 6 This is the performance diagram of 1000mM hydrogen peroxide degrading tetracycline in water;

[0028] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the following embodiments are based on the present technical solution and provide detailed implementation methods and specific operating processes, but the protection scope of the present invention is not limited to these embodiments.

[0030] Example 1

[0031] Preparation of water oxidation material electrodes:

[0032] Nano-scale water oxidation material powders such as zinc gallium oxide, bismuth tungstate, copper tungstate, bismuth antimonate, zinc tungstate, and antimony tungstate are prepared by hydrothermal method. The water oxidation material is first mixed with polyvinylidene fluoride (PVDF) at a ratio of about 2 to 3:1, and then an appropriate amount of N-methylpyrrolidone (NMP) liquid is added and stirred for 5 minutes to form a non-stick slurry. The prepared slurry is dripped on a substrate material such as a carbon-based material, FTO conductive glass, titanium sheet, foamed nickel, foamed copper, etc., placed in an oven, and baked at 150°C for 5 minutes to 10 minutes to prepare an anode electrode sheet.

[0033] Example 2

[0034] Degradation of different concentrations of tetracycline by mixed treatment solution:

[0035] Step 1: Set up the electrochemical environment, electrochemical double cell, separate the cathode and cathode by the nafion membrane that only allows protons to pass through, the anode is carbon paper loaded with water oxidation material zinc tungstate, the cathode is graphite sheet, and the electrolyte is a mixture of 3.5M potassium carbonate and 0.5M potassium bicarbonate. Then electrocatalyze the water oxidation reaction at 3.2V versus RHE for 30min, and test its peroxide concentration of 50mM.

[0036] Step 2: Take 5 mL of electrolyte, i.e., treatment solution, and add it to 50 mL of water samples with different tetracycline concentrations. Stir at 300 rpm for 1 hour, and then let it stand for 20 hours. Samples were taken at 1 min, 10 min, 20 min, 40 min, 60 min, 90 min, and 1200 min, with 2 mL sampled each time. Water samples 1-6 and 2-6 were obtained.

[0037] Step 3: Detect the absorbance of tetracycline in samples 1-6 and 2-6 obtained in step 2 by UV-visible spectrophotometry.

[0038] The results are as follows Figure 1 As shown, it can be seen that:

[0039] Tetracycline is continuously degraded with time. After adding the mixed treatment solution for 1200 minutes, tetracycline of different concentrations is degraded to about 90%.

[0040] Therefore, this method can effectively degrade tetracycline in water and maintain stable degradation for a long time.

[0041] Example 3

[0042] Degradation of different concentrations of oxytetracycline by mixed treatment solution:

[0043] Step 1: Set up the electrochemical environment, electrochemical double cell, separate the cathode and cathode by the nafion membrane that only allows protons to pass through, the anode is carbon paper loaded with water oxidation material zinc tungstate, the cathode is graphite sheet, and the electrolyte is a mixture of 3.5M potassium carbonate and 0.5M potassium bicarbonate. Then electrocatalyze the water oxidation reaction at 3.2V versus RHE for 30min, and test its peroxide concentration of 50mM.

[0044] Step 2: Take 5 mL of the electrolyte, i.e., the treated solution, and add it to 50 mL of water samples with different oxytetracycline concentrations. Stir at 300 rpm for 1 hour, and then let it stand for 20 hours. Sampling was performed at 1 min, 10 min, 20 min, 40 min, 60 min, 90 min, and 1200 min, with 2 mL sampled each time. Water samples 3-6 and 4-6 were obtained.

[0045] Step 3: Detect the absorbance of tetracycline in samples 3-6 and 4-6 obtained in step 2 by UV-visible spectrophotometry.

[0046] The results are as follows Figure 2 As shown, it can be seen that:

[0047] Oxytetracycline was degraded continuously with the increase of time. After adding the mixed treatment solution for 1200 minutes, oxytetracycline of different concentrations was degraded to more than 80%.

[0048] Therefore, this method can effectively degrade oxytetracycline in water and maintain stable degradation for a long time.

[0049] Example 4

[0050] Degradation of tetracycline-containing aquaculture water by mixed treatment liquid:

[0051] Step 1: Set up the electrochemical environment, electrochemical double cell, separate the cathode and cathode by the nafion membrane that only allows protons to pass through, the anode is carbon paper loaded with water oxidation material zinc tungstate, the cathode is graphite sheet, and the electrolyte is a mixture of 3.5M potassium carbonate and 0.5M potassium bicarbonate. Then electrocatalyze the water oxidation reaction at 3.2V versus RHE for 30min, and test its peroxide concentration of 50mM.

[0052] Step 2: Take 5 mL of the electrolyte, i.e., the treatment solution, and add it to 50 mL of aquaculture water containing tetracycline at a tetracycline concentration of 25 ppm as the treatment group. At the same time, set up a control group without the treatment solution. Stir the two at the same time at a speed of 300 rpm for 1 hour, and then let it stand for 20 hours. Samples were taken at 1 minute, 10 minutes, 20 minutes, 40 minutes, 60 minutes, 90 minutes, and 1200 minutes, and 2 mL was sampled each time. Water samples 5-6 and 6-6 were obtained.

[0053] Step 3: Detect the absorbance of tetracycline in samples 5-6 and 6-6 obtained in step 2 by UV-visible spectrophotometry.

[0054] The results are as follows Figure 3 As shown, it can be seen that:

[0055] Tetracycline was continuously degraded as time went by. However, the control group without treatment solution was not degraded in the same period of time. After adding the mixed treatment solution for 1200 minutes, tetracycline was degraded by more than 90%.

[0056] Therefore, this method can effectively degrade tetracycline in aquaculture water and maintain stable degradation for a long time.

[0057] Example 5

[0058] Degradation of oxytetracycline-containing aquaculture water by mixed treatment liquid:

[0059] Step 1: Set up the electrochemical environment, electrochemical double cell, separate the cathode and cathode by the nafion membrane that only allows protons to pass through, the anode is carbon paper loaded with water oxidation material zinc tungstate, the cathode is graphite sheet, and the electrolyte is a mixture of 3.5M potassium carbonate and 0.5M potassium bicarbonate. Then electrocatalyze the water oxidation reaction at 3.2V versus RHE for 30min, and test its peroxide concentration of 50mM.

[0060] Step 2: Take 5 mL of the electrolyte, i.e., the treatment solution, and add it to 50 mL of aquaculture water containing oxytetracycline with a concentration of 25 ppm as the treatment group. At the same time, set up a control group without the treatment solution. Stir the two at the same time at a speed of 300 rpm for 1 hour, and then let it stand for 20 hours. Samples are taken at 1 minute, 10 minutes, 20 minutes, 40 minutes, 60 minutes, 90 minutes, and 1200 minutes, and 2 mL is sampled each time. Water samples 7-6 and 8-6 are obtained.

[0061] Step 3: Detect the absorbance of oxytetracycline in water samples 7-6 and 8-6 obtained in step 2 by UV-visible spectrophotometry.

[0062] The results are as follows Figure 4As shown, it can be seen that:

[0063] Oxytetracycline was degraded over time. The control group without treatment solution was not degraded in the same time. After adding the mixed treatment solution for 1200 minutes, oxytetracycline was degraded by more than 80%.

[0064] Therefore, this method can effectively degrade oxytetracycline in aquaculture water and maintain stable degradation for a long time.

[0065] Example 6

[0066] 100mM and 1000mM hydrogen peroxide degrade tetracycline water samples:

[0067] Step 1: Take 5 mL of 100 mM / 1000 mM hydrogen peroxide and add it to 25 ml of wastewater with a tetracycline concentration of 25 ppm. Stir at a speed of 300 rpm. The reaction lasts for 1 hour, and then stands for 4 hours. Samples are taken at 1 minute, 10 minutes, 20 minutes, and 240 minutes, and 2 mL is sampled each time. Water samples 9-6 and 10-6 are obtained.

[0068] Step 2: UV-visible spectrophotometry was used to detect the absorbance of tetracycline in water 9-6 and 10-6 obtained in step 2. The results are as follows: Figure 5 and Figure 6 As shown, it can be seen that:

[0069] In the 100mM hydrogen peroxide group, the peak absorbance of tetracycline did not decrease over time, indicating that hydrogen peroxide did not degrade tetracycline, and no degradation of tetracycline occurred after long-term storage. In the 1000mM hydrogen peroxide group, the peak absorbance of tetracycline did not decrease over time, and a small decrease in the peak absorbance of tetracycline was detected only at 240 minutes, indicating that the degradation effect was not obvious. Therefore, it is difficult for hydrogen peroxide alone to degrade tetracycline.

[0070] In summary, it can be seen that compared with the commonly used treatment liquid such as hydrogen peroxide, the method described in the present application utilizes water widely present in the environment as raw material, supplemented by cheap and readily available carbonates and bicarbonates, to quickly prepare a treatment liquid with better effect on site. It is convenient and quick to use, has obvious treatment effect, and has great practical application prospects.

[0071] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present invention.

Claims

1. A method for degrading tetracycline and oxytetracycline by electrocatalytic water oxidation production treatment liquid, the method comprising the following steps: (1) Preparation of electrocatalytic water oxidation treatment solution: The electrocatalytic environment and electrochemical double cell were set up. The anode was carbon paper loaded with tungstate, a water oxidation material, and the cathode was graphite sheet. The electrolyte was a mixture of 0-3.5M potassium carbonate and 0-0.5M potassium bicarbonate. Then, the electrocatalytic water oxidation reaction was carried out at 2.0-4V versus RHE for 30-60min to obtain hydrogen peroxide (H2O2) and hydroperoxide anions (HO2 - ) treatment fluid; (2) The electrocatalytic water oxidation treatment liquid degrades tetracycline antibiotic pollutants: At room temperature and pressure, an appropriate volume of the electrocatalytic water oxidation treatment solution of step (1) is taken out, placed in a water sample containing tetracycline antibiotics and stirred, without adding any chemical reagents or other operations, to obtain a solution 1; wherein the hydroperoxide anion (HO2 - ) and hydrogen peroxide (H2O2) have strong oxidizing properties and can directly oxidize and degrade tetracycline.

2. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that: In the step (1), the anode in the electrocatalytic environment is loaded with a carbon electrode of water oxidation materials such as bismuth antimonate, copper tungstate, bismuth tungstate, zinc tungstate, antimony tungstate, zinc gallium oxide, etc., wherein the water oxidation material is first mixed with polyvinylidene fluoride (PVDF) at a ratio of about 2 to 3:1, and then an appropriate amount of N-methylpyrrolidone (NMP) liquid is added and stirred for 5 minutes to form a non-stick slurry. The prepared slurry is dripped onto a substrate material such as a carbon-based material, FTO conductive glass, titanium sheet, foamed nickel, foamed copper and the like, placed in an oven, and baked at 150°C for 5 minutes to 10 minutes to prepare an anode electrode sheet. The cathode is a graphite sheet.

3. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that: The electrolyte in the electrocatalytic environment in step (1) is a mixture of 0-3.5M potassium carbonate and 0-0.5M potassium bicarbonate.

4. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that: The electrocatalytic reaction time in step (1) is 30 to 60 minutes.

5. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that: The device in step (1) is an electrochemical double cell, the anode and cathode are separated by a nafion membrane that only allows protons to pass through, and the electrocatalytic water oxidation voltage is 2.0-4V versus RHE.

6. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that: The concentration of tetracycline antibiotics in the wastewater of step (2) is 1 ppm-50 ppm.

7. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that: The volume of the treatment liquid in step (2) is 0-1 / 30 of the volume of the wastewater.

8. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that: In the step (2), the speed is set at 300 rpm and the stirring time is 1 hour.

9. The method for degrading tetracycline antibiotics by electrocatalytic water oxidation production treatment liquid according to claim 1, characterized in that The tetracycline contaminants treated include tetracycline, oxytetracycline, and chlortetracycline.

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