Method for selectively removing tetracycline antibiotics in water

Abstract

The invention discloses a method for selectively removing tetracycline antibiotics in water, and relates to the field of wastewater treatment. The core technology of the method is as follows: the TCs in the water are selectively removed by using complex interaction between background matrixes such as Mn (II) and HCO3 in the wastewater and the TCs and adding an oxidizing agent H2O2 at the same time. The method can selectively and efficiently remove TCs in water, has the advantages of simplicity in operation, low cost, environmental friendliness, difficulty in interference of background matrixes and the like, has a wide application prospect in the field of water pollution control, and is a new discovery for developing a water pollution control technology based on pollutant properties and the background matrixes in water.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, and in particular to a method for selectively removing tetracycline antibiotics from water. Background Technology

[0002] Tetracycline antibiotics (TCs) are among the most widely used antibiotics. TCs exhibit good antibacterial effects against Gram-negative bacteria, Gram-positive bacteria, mycoplasma, chlamydia, rickettsia, and protozoa. Therefore, TCs are widely used in clinical medicine, animal husbandry, and aquaculture. There are many types of TCs, including not only the widely used tetracycline (TTC), oxytetracycline (OTC), and chlortetracycline (CTC), but also minocycline, doxycycline, and others. In recent years, TCs have been frequently detected in aquatic environments, with concentrations in surface water generally ranging from 0.1 ng / L to 0.98 μg / L. TCs can persist stably in natural water bodies, thus accumulating through the food chain and exerting toxic effects on humans and other organisms. For example, oxytetracycline can regulate steroid-related gene expression and hormone production, causing endocrine disorders in organisms. Therefore, the water pollution caused by TCs is receiving increasing attention.

[0003] Industrial and medical wastewater discharge is one of the main sources of total chemical (TC) pollution in water. However, TCs in wastewater are difficult to biodegrade. Therefore, it is necessary to develop chemical methods to effectively degrade and remove TCs from wastewater. It is worth noting that trace elements such as ferrous iron (Fe(II)) and manganese divalent (Mn(II)) are introduced during the preparation of TCs, and wastewater often contains dissolved organic matter (DOM) and bicarbonate (HCO3-). – Background matrices such as TCs and sulfates are present in the water. Therefore, the composition of TCs wastewater is complex, making the selective removal of TCs from wastewater a challenging problem in water pollution control. Advanced oxidation processes (AOPs) are a commonly used water pollution control technology that generates highly reactive oxidants with strong oxidizing capabilities, such as hydroxyl radicals, sulfate radicals, and intermediate valence metals, thereby effectively removing organic pollutants from water. However, in practical applications, AOPs are easily interfered with by background matrices in the water, making selective removal of TCs difficult. To achieve selective removal of TCs from wastewater, it is necessary to develop AOPs that combine both oxidizing power and selectivity.

[0004] HCO3 – Mn(II) and Mg2+ are common background matrices in wastewater and important precursors for the formation of active oxidants in AOPs. Hydrogen peroxide / bicarbonate activation system (H2O2 / HCO3) ‒ The BAP system is a type of AOP that has been widely reported in recent years. H2O2 and HCO3 ‒The mixed solution can be activated in various ways, such as by UV, ultrasound, and transition metals, to generate highly selective active oxidants to remove pollutants from water. Among these, Mn(II) activates H₂O₂ / HCO₃. ‒ Process (Mn(II) / H2O2 / HCO3) ‒ The Mn(II) / H₂O₂ / HCO₃ system has received widespread attention in recent years. It is an important process in human biochemistry and is also widely used in organic chemical synthesis and water treatment. Some scholars have discovered that under pH 8.5 conditions, the Mn(II) / H₂O₂ / HCO₃ system... ‒ The system can effectively oxidize arsenic in water. Given that TCs can complex with transition metal ions in solution, thereby enhancing the removal of TCs by AOPs, the complexation of TCs with Mn(II) may enable its removal by Mn(II) / H₂O₂ / HCO₃. ‒ Selective removal of pollutants is possible. However, there is currently limited research on constructing AOPs based on pollutant properties and background matrix in wastewater to achieve selective pollutant removal, necessitating further development of related water pollution control technologies. Summary of the Invention

[0005] To address the problem of the difficulty in selectively and efficiently removing tetracycline antibiotics (TCs) from wastewater, the main objective of this invention is to propose a method for the selective removal of tetracycline antibiotics from water. This method utilizes Mn(II) and HCO3- in the wastewater... ‒ The complex interaction between the background matrix and TCs is addressed by adding the oxidant H2O2 to selectively remove TCs from water. Specifically, the steps include: (1) adding a certain concentration of Mn(II) and HCO3-. ‒ (1) Mix with TCs solution to obtain reaction solution; (2) Adjust the pH value of the reaction solution in step (1) to the set value; (3) Add H2O2 to the solution with pH adjusted in step (2) and react for a period of time.

[0006] In the above method, the divalent manganese is manganese sulfate, manganese chloride, manganese nitrate, or manganese acetate; the bicarbonate is sodium bicarbonate, sodium carbonate, potassium bicarbonate, or potassium carbonate; and the concentration of TCs in the reaction solution is greater than 10 μmol•L. −1 The ratio of TCs to Mn(II) in the reaction solution is 10:20000~800:5000; the ratio of Mn(II) to H2O2 in the reaction solution is 5:800~80:100; the mixing method is magnetic stirring; the pH of the reaction system is 8.5~10.0.

[0007] The beneficial effects of this invention are as follows: (1) This invention uses the background matrix present in wastewater as reactants to construct AOPs, which has the advantages of simple operation, low cost, and environmental friendliness. (2) In this invention, TCs are simultaneously removed during the decomposition of H2O2 by Mn(II) catalysis. Therefore, this invention can selectively remove TCs in water and is not easily affected by the background matrix. (3) This invention can achieve selective removal of TCs under environmental pH conditions, and will not cause drastic changes in the pH of the water body during use. Attached Figure Description

[0008] Figure 1 shows the Mn(II) / H2O2 / HCO3 ratio in Example 1. ‒ The system's removal rates for nine organic pollutants and four TCs; Figure 2 For different H2O2 concentrations in Example 2, the Mn(II) / H2O2 / HCO3 ratio was calculated. ‒ Kinetic curves of TTC removal from the system (in the figure) C / C 0 represents the ratio of TTC concentration at time t to the initial TTC concentration (the same applies below). Figure 3 For example 3, under different Mn(II) concentrations, the Mn(II) / H2O2 / HCO3 ratio was calculated. ‒ Kinetic curves of TTC removal from the system; Figure 4 Different HCO3 in Example 4 ‒ Under certain concentration conditions, Mn(II) / H2O2 / HCO3 ‒ Kinetic curves of TTC removal from the system; Figure 5 For the Mn(II) / H2O2 / HCO3 under different pH conditions in Example 5 ‒ Kinetic curves of TTC removal from the system; Figure 6 Under the high concentration TTC conditions in Example 6, Mn(II) / H2O2 / HCO3 ‒ Kinetic curves of TTC removal from the system; Figure 7 Different HA and Cl in Example 7 ‒ Under certain concentration conditions, Mn(II) / H2O2 / HCO3 ‒ Kinetic curves of TTC removal from the system. Detailed Implementation

[0009] Example 1

[0010] In a moderately alkaline solution, Mn(II) / H₂O₂ / HCO₃ ‒The system can oxidize pollutants in water. In this embodiment, nine organic pollutants and four TCs were selected as target pollutants, and the removal rate of the method of the present invention on them was investigated. The specific steps are as follows: (1) A certain concentration of Mn(II) and HCO3- were added. ‒ (1) Mix with the organic pollutant solution to obtain a reaction solution; (2) Adjust the pH of the reaction solution in step (1) to 9.0; (3) Add H2O2 to the solution whose pH has been adjusted in step (2) and react for 20 min.

[0011] The organic pollutant is one of ciprofloxacin (CIP), sulfamethoxazole (SMX), penicillin G (PENG), tetracycline (TTC), phenol, tryptophan (TRP), naproxen (NPX), carbamazepine (CBZ), chlortetracycline (CTC), minocycline (MNC), and tigecycline (TGC); the reaction system is Mn(II) / H2O2 / HCO3. ‒ The system; the mixing method is magnetic stirring; the reaction solution contains Mn(II), H2O2, and HCO3. ‒ The initial concentrations of organic pollutants were 40 μmol•L. −1 800 μmol•L −1 20 mmol•L −1 and 20 μmol•L −1 The reaction solution has a reaction pH of 9.0.

[0012] Figure 1 The Mn(II) / H2O2 / HCO3 ratio was shown. ‒ The system's removal rates for nine organic pollutants and four TCs were measured. The Mn(II) / H₂O₂ / HCO₃ ratio at pH 9.0 was also considered. – The system removed less than 10.0% of CIP, SMX, phenol, TRP, NPX, and CBZ within 20 min. Mn(II) / H2O2 / HCO3 – The system removed 35.5% of PENG within 20 min, while achieving a removal rate of 98.0% for TTC. Therefore, at pH 9.0, the Mn(II) / H2O2 / HCO3 ratio... – The system can selectively remove TTC. Besides TTC, the Mn(II) / H₂O₂ / HCO₃ ratio is reduced within 20 min. – The system achieved removal rates of 76.0%, 92.0%, and 61.0% for the other three TCs, namely CTC, MNC, and TGC, respectively. Therefore, the Mn(II) / H2O2 / HCO3 ratio... – The system can selectively remove TCs.

[0013] Example 2

[0014] As the concentration of H2O2 increases, the ratio of Mn(II) / H2O2 / HCO3 increases. ‒ The system's oxidizing capacity is enhanced, and changing the initial concentration of H2O2 can increase the rate of TC removal. TTC was selected as the target pollutant to investigate the effect of the initial H2O2 concentration on the TC removal efficiency of this method; the specific steps are the same as in Example 1.

[0015] Unlike Example 1, the initial concentration of H2O2 in the reaction solution is 100~800 μmol•L. −1 .

[0016] Figure 2 The ratio of Mn(II) / H2O2 / HCO3 was shown under different H2O2 concentrations. ‒ Kinetic curves for TTC removal from the system. When the initial H₂O₂ concentration is 100 μmol•L⁻¹. −1 200 μmol•L −1 400 μmol•L −1 and 800 μmol•L −1 At that time, Mn(II) / H2O2 / HCO3 – The system achieved TTC removal rates of 16.0%, 30.0%, 48.5%, and 66.0% within 1 min, respectively. Furthermore, when the initial H2O2 concentration was greater than 200 μmol•L... −1 At that time, the removal rate of TTC was above 90.0% within 20 min. Therefore, the Mn(II) / H2O2 / HCO3 ratio... – The removal rate of TTC by the system increases with increasing initial H2O2 concentration. This example illustrates that changing the initial H2O2 concentration can improve the efficiency of TC removal in this invention.

[0017] Example 3

[0018] Increasing the initial concentration of Mn(II) can also enhance the Mn(II) / H2O2 / HCO3 ratio. ‒ The oxidation capacity of the system is improved, thereby increasing the rate of TC removal. TTC was selected as the target pollutant to investigate the effect of the initial Mn(II) concentration on the TC removal efficiency of this method. The specific steps are the same as in Example 1.

[0019] Unlike Example 1, the initial concentration of Mn(II) in the reaction solution was 5~80 μmol•L. −1 .

[0020] Figure 3 This shows the Mn(II) / H2O2 / HCO3 ratio under different Mn(II) concentrations.‒ Kinetic curves for TTC removal from the system. When the initial Mn(II) concentration is 5 μmol•L... −1 10 μmol•L −1 20 μmol•L −1 40 μmol•L −1 and 80 μmol•L −1 At that time, Mn(II) / H2O2 / HCO3 – The removal rates of TTC by the system within 5 min were 41.0%, 61.0%, 81.0%, 95.5%, and 96.0%, respectively. Furthermore, when the initial concentration of Mn(II) was 40 μmol•L... −1 and 80 μmol•L −1 At that time, the removal rate of TTC was higher than 98.0% within 20 min, while the initial concentration of Mn(II) was 20 μmol•L. −1 The removal rate was 95.0%. This example illustrates that changing the initial concentration of Mn(II) can improve the efficiency of TC removal in this invention.

[0021] Example 4

[0022] Mn(II) / H2O2 / HCO3 ‒ The system's oxidation capacity is also affected by HCO3. ‒ The effect of initial concentration. TTC was selected as the target pollutant to investigate HCO3. ‒ The effect of initial concentration on the TCs removal efficiency of this method is explained in the same steps as in Example 1.

[0023] Unlike Example 1, the reaction solution contained HCO3 ‒ The initial concentrations were 5–40 mmol•L. −1 20 μmol•L −1 .

[0024] Figure 4 Different HCO3 were shown ‒ Under certain concentration conditions, Mn(II) / H2O2 / HCO3 ‒ Kinetic curves of TTC removal from the system. When HCO3... – The initial concentration was 5 mmol•L. −1 At that time, Mn(II) / H2O2 / HCO3 – The system achieved a TTC removal rate of 77.5% within 10 minutes. However, when HCO3... – Initial concentration: 10–40 mmol·L −1 At that time, Mn(II) / H2O2 / HCO3 –The system achieved a TTC removal rate exceeding 95.0% within 10 minutes. Therefore, HCO3... – The initial concentration affects the Mn(II) / H2O2 / HCO3 ratio. – The system's removal efficiency for TTC.

[0025] Example 5

[0026] Under moderately alkaline conditions, this method can effectively remove TCs from water. TTC was selected as the target pollutant to investigate the removal efficiency of this method for TCs under different pH conditions; the specific steps are the same as in Example 1.

[0027] Unlike Example 1, the reaction pH of the reaction solution is 7.0~10.0.

[0028] Figure 5 The Mn(II) / H2O2 / HCO3 ratio was shown under different pH conditions. ‒ Kinetic curves of TTC removal by the system. When the solution pH increases from 7.0 to 10.0, the ratio of Mn(II) / H₂O₂ / HCO₃ changes. – The removal rates of TTC by the system within 20 min were 20.5% (pH 7.0), 37.0% (pH 7.5), 80.0% (pH 8.0), 94.5% (pH 8.5), 98.0% (pH 9.0), 99.0% (pH 9.5), and 100% (pH 10.0). Therefore, when the pH increased from 7.0 to 8.5, the Mn(II) / H2O2 / HCO3 ratio within 20 min was [data missing]. – The removal rate of TTC by the system increases with increasing solution pH, but is almost unaffected by solution pH when pH > 8.5. This example illustrates the effectiveness of the Mn(II) / H2O2 / HCO3 system under moderately alkaline conditions. ‒ The system can efficiently remove TTC.

[0029] Example 6

[0030] This method exhibits a high removal capacity for total toxic substances (TCs) in water. TTC was selected as the target pollutant to investigate the removal efficiency of this method for TCs under high TTC concentration conditions. The specific steps are the same as in Example 1.

[0031] Unlike Example 1, the initial concentration of TTC in the reaction solution was 250 and 800 μmol•L. −1 The reaction time is 2 hours.

[0032] Figure 6 Under high concentration TTC conditions, Mn(II) / H2O2 / HCO3 ‒Kinetic curves for TTC removal from the system. Within 2 h of reaction, the ratio of Mn(II) / H₂O₂ / HCO₃... – The system is effective against 250 μmol•L −1 and 800 μmol•L −1 The removal rates of TTC were 95.0% and 46.0%, respectively, which means that the Mn(II) / H2O2 / HCO3 ratio was within 2 hours. – The system can remove up to 350 μmol•L −1 The TTC. Therefore, under moderately alkaline conditions, Mn(II) / H2O2 / HCO3 – The system has a large removal capacity for TTC. This example illustrates the potential application of this invention as a water pollution control technology.

[0033] Example 7

[0034] Under moderately alkaline conditions, the removal efficiency of this method for TCs is not significantly affected by the background matrix in the water. TTC was selected as the target pollutant, along with humic acid (HA) and chloride ions (Cl). ‒ As a representative of the background matrix in water, the influence of the background matrix in water on the efficiency of this method in removing TCs was investigated. The specific steps are the same as in Example 1.

[0035] Unlike Example 1, the reaction solution contains HA and Cl. ‒ The initial concentrations were 0–5 mg C•L. −1 and 0~10 mmol•L −1 .

[0036] Figure 7 For different HA and Cl ‒ Under certain concentration conditions, Mn(II) / H2O2 / HCO3 ‒ Kinetic curves for TTC removal from the system. The results show that HA and Cl... – It has almost no effect on the Mn(II) / H2O2 / HCO3 ratio. – The kinetics of TTC removal from the system. This example illustrates the Mn(II) / H₂O₂ / HCO₃ combination under alkaline conditions. – The system's removal efficiency for TTC is almost unaffected by the background matrix in the water.

Claims

1. A method for selectively removing tetracycline antibiotics from water, characterized in that, Includes the following steps: (1) Mix a certain concentration of divalent manganese, bicarbonate and tetracycline antibiotic solution to obtain a reaction solution; (2) Adjust the pH of the reaction solution in step (1) to 8.5~10.0; (3) Add hydrogen peroxide to the solution in step (2) with the pH adjusted, and react for a period of time.

2. The method for selectively removing tetracycline antibiotics from water according to claim 1, characterized in that: The divalent manganese mentioned is manganese sulfate, manganese chloride, manganese nitrate, or manganese acetate.

3. The method for selectively removing tetracycline antibiotics from water according to claim 1, characterized in that: The bicarbonate mentioned is sodium bicarbonate, sodium carbonate, potassium bicarbonate, or potassium carbonate.

4. The method for selectively removing tetracycline antibiotics from water according to claim 1, characterized in that: The stirring method described is magnetic stirring.

5. The method for selectively removing tetracycline antibiotics from water according to claim 1, characterized in that: The reaction pH of the method is 8.5~10.

0.

6. The method for selectively removing tetracycline antibiotics from water according to claim 1, characterized in that: The ratio of TCs to Mn(II) in the reaction solution is 10:20000~800:5000.

7. The method for selectively removing tetracycline antibiotics from water according to claim 1, characterized in that: In the method described, the ratio of divalent manganese to hydrogen peroxide is 5:800 to 80:100.

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