Method for degrading tetracycline antibiotics in water body

Abstract

The invention provides a method for degrading tetracycline antibiotics in a water body. The degradation method comprises the following steps: preparing an AgCl / MIL-100 (Fe) MOF material, mixing the MOF material, TiO2 and ZnO with a water body containing the tetracycline antibiotics under a dark condition, controlling the mass ratio of the MOF material to the TiO2 to the ZnO to be 1: (0.1-0.5): (1.2-2.5), and then turning on a light source to carry out photocatalytic reaction so as to degrade the tetracycline antibiotics in the water body. According to the degradation method, the MOF material with excellent performance is obtained through a specific method, and the MOF material is mixed with TiO2 and ZnO, so that the degradation rate of tetracycline antibiotics in the water body can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of water pollution control, and in particular to a method for degrading tetracycline antibiotics in water. Background Art

[0002] With the rapid development of medicine and animal husbandry, tetracycline antibiotics have become widely used in clinical treatment and livestock farming due to their broad-spectrum antimicrobial properties. However, due to their difficulty in being fully metabolized by organisms, large amounts of unused tetracycline antibiotics enter the aquatic environment through wastewater discharge. Tetracycline antibiotics in water bodies not only disrupt the balance of aquatic ecosystems and affect the growth and reproduction of aquatic organisms, but can also be transmitted through the food chain, posing a potential threat to human health. Furthermore, the long-term presence of tetracycline antibiotics in water bodies can induce bacterial resistance, further exacerbating public health issues.

[0003] Currently, the treatment methods for tetracycline antibiotics in water bodies mainly include physical methods, chemical methods and biological methods. Although physical methods such as adsorption are simple to operate, they only transfer antibiotics from the water body to the adsorbent, without fundamentally eliminating the pollution. In addition, there is a saturation problem of the adsorbent, making subsequent treatment difficult. Advanced oxidation technology in chemical methods can effectively degrade antibiotics, but it often requires the use of a large amount of chemical reagents, which is costly and may also cause secondary pollution. Biological treatment efficiency is relatively low, the treatment cycle is long, and the environmental conditions are demanding. It is difficult to deal with high-concentration, complex composition antibiotics contaminated water bodies. Therefore, it is of great practical significance to develop an efficient, environmentally friendly and economical method for degrading tetracycline antibiotics in water bodies. Summary of the Invention

[0004] Based on the above problems, the present invention provides a method for degrading tetracycline antibiotics in water. By preparing a specific AgCl / MIL-100 (Fe) MOF material and rationally mixing it with TiO2 and ZnO, an efficient composite photocatalytic system is constructed to achieve rapid and efficient degradation of tetracycline antibiotics in water, overcoming the shortcomings of the existing technology.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A method for degrading tetracycline antibiotics in water comprises the following steps: S101: Preparation of AgCl / MIL-100 (Fe) MOF material: Dissolving an iron ion source and trimesic acid in water, and adjusting the pH value to 4.5-5.5 to obtain a reaction solution; The reaction solution was stirred at 20°C-30°C for 20h-30h, and then washed and dried to obtain MIL-100 (Fe); The MIL-100 (Fe) was mixed with a silver ion solution, stirred for 2 h to 5 h, and then a chloride ion solution was added dropwise, and stirred for 5 h to 10 h under natural light irradiation conditions, and then washed and dried to obtain an AgCl / MIL-100 (Fe) MOF material; S102: Photocatalytic degradation: The AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO are mixed with water containing tetracycline antibiotics under dark conditions, and the mass ratio of the AgCl / MIL-100 (Fe) MOF material, the TiO2 and the ZnO is controlled to be 1: (0.1-0.5): (1.2-2.5). The mixed system is stirred in the dark for 0.5h-1h, and then a light source is turned on to carry out a photocatalytic reaction. The light source is a visible light source, and the light intensity of the light source is 50mW / cm²-200mW / cm².

[0006] Optionally, the reaction temperature of the photocatalytic reaction is 20° C.-30° C., and the reaction time is 1 h-3 h.

[0007] Optionally, the visible light source is a tungsten light source with a 400nm cut-off filter.

[0008] Optionally, the mass ratio of the AgCl / MIL-100 (Fe) MOF material, the TiO2 and the ZnO is 1:0.3:2.

[0009] Optionally, the molar ratio of the iron ions in the iron ion source to the trimesic acid is 1:(1.1-1.5).

[0010] Optionally, the iron ion source includes at least one of FeCl3·4H2O and Fe(NO3)3·9H2O.

[0011] Optionally, the molar concentration of silver ions in the silver ion solution is 50 mmol / L-60 mmol / L.

[0012] Optionally, the molar concentration of chloride ions in the chloride ion solution is 10 mmol / L-15 mmol / L.

[0013] Optionally, the volume ratio of the silver ion solution to the chloride ion solution is 1:(3-5).

[0014] Optionally, the mass ratio of the MIL-100 (Fe) to the silver ions in the silver ion solution is 1: (1.1-1.3).

[0015] Beneficial effects The AgCl / MIL-100(Fe) MOF material, obtained through a specific preparation method, possesses a high specific surface area and abundant active sites, enabling effective adsorption of tetracycline antibiotics. Furthermore, when mixed with TiO2 and ZnO in a specific mass ratio, the resulting composite photocatalytic system significantly improves the separation efficiency of photogenerated charge carriers and broadens the photoresponse range, thereby achieving efficient degradation of tetracycline antibiotics in water. In some embodiments, the degradation method of the present invention can achieve a degradation rate of over 95% for tetracycline antibiotics.

[0016] In addition, the degradation method of the present invention mainly utilizes a photocatalytic reaction, does not require the use of large amounts of chemical reagents, has mild reaction conditions, and does not produce secondary pollution. At the same time, the raw materials used in the degradation method are relatively low in cost, with good economic and environmental benefits.

[0017] Furthermore, the entire degradation process of the present invention is simple to operate, requires minimal reaction equipment, and is readily applicable for industrial applications. By controlling parameters such as material ratios and reaction conditions, the degradation efficiency can be flexibly adjusted to meet the treatment requirements for tetracycline antibiotic contamination in different water bodies. DETAILED DESCRIPTION

[0018] One embodiment of the present invention provides a method for degrading tetracycline antibiotics in water. The method for degrading tetracycline antibiotics in water comprises the following steps: S101: Preparation of AgCl / MIL-100(Fe)MOF: Dissolve an iron ion source and trimesic acid in water and adjust the pH to 4.5-5.5 to obtain a reaction solution. Stir the reaction solution at 20°C-30°C for 20-30 hours, then wash and dry to obtain MIL-100(Fe). Mix MIL-100(Fe) with a silver ion solution and stir for 2-5 hours. Then, add a chloride ion solution dropwise and stir under natural light for 5-10 hours. Wash and dry to obtain the AgCl / MIL-100(Fe)MOF material.

[0019] S102: Photocatalytic degradation: Mix AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO with water containing tetracycline antibiotics under dark conditions, and control the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO to 1: (0.1-0.5): (1.2-2.5). Stir the mixed system in the dark for 0.5h-1h, and then turn on the light source for photocatalytic reaction. The light source is a visible light source, and the light intensity of the light source is 50mW / cm²-200mW / cm².

[0020] In this degradation method, the AgCl / MIL-100(Fe)MOF material, obtained through a specific preparation method, possesses a high specific surface area and abundant active sites, enabling effective adsorption of tetracycline antibiotics. Furthermore, by mixing it with TiO2 and ZnO in a specific mass ratio, the resulting composite photocatalytic system significantly improves the separation efficiency of photogenerated charge carriers and broadens the photoresponse range, thereby achieving efficient degradation of tetracycline antibiotics in water.

[0021] In addition, the degradation method of the present invention mainly utilizes a photocatalytic reaction, does not require the use of large amounts of chemical reagents, has mild reaction conditions, and does not produce secondary pollution. At the same time, the raw materials used in the degradation method are relatively low in cost, with good economic and environmental benefits.

[0022] Furthermore, the entire degradation process of the present invention is simple to operate, requires minimal reaction equipment, and is readily applicable for industrial applications. By controlling parameters such as material ratios and reaction conditions, the degradation efficiency can be flexibly adjusted to meet the treatment requirements for tetracycline antibiotic contamination in different water bodies.

[0023] Optionally, the molar ratio of iron ions in the iron ion source to trimesic acid is 1:(1.1-1.5). This molar ratio of iron ions in the iron ion source to trimesic acid within this range can reduce defects in the crystal structure of MIL-100(Fe) and increase its porosity. For example, when the molar ratio of iron ions in the iron ion source to trimesic acid is greater than 1:1.1, the resulting MIL-100(Fe) has a relatively regular octahedral crystal structure and high porosity, which is conducive to the subsequent loading of Ag⁺ and the adsorption of tetracycline antibiotics. However, when the molar ratio of iron ions in the iron ion source to trimesic acid is greater than 1:1.5, the crystal structure exhibits increased defects and improved porosity, but the crystal stability decreases slightly. Therefore, the molar ratio of iron ions in the iron ion source to trimesic acid is preferably 1:(1.1-1.5). For example, the molar ratio of iron ions in the iron ion source to trimesic acid can be 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc. It is understood that the molar ratio of iron ions in the iron ion source to trimesic acid can also be selected from other suitable ranges within the range of 1:(1.1-1.5). Alternatively, the molar ratio of iron ions in the iron ion source to trimesic acid is 1:1.2. Optionally, the iron ion source includes at least one of FeCl₃·4H₂O and Fe(NO₃)₃·9H₂O.

[0024] Optionally, in S101, during the stirring of the reaction solution at 20° C.-30° C. for 20-30 hours, the stirring speed may be 300 rpm-500 rpm. For example, the stirring speed may be 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, etc. It is understood that the stirring speed may also be other suitable selections within the range of 300 rpm-500 rpm.

[0025] Optionally, in S101, during the reaction of stirring the reaction solution at 20°C-30°C for 20-30 hours, the reaction temperature may be 20°C, 22°C, 25°C, 28°C, 30°C, etc. It is understood that the reaction temperature may be other suitable selections within the range of 20°C-30°C. Optionally, the reaction time may be 20 hours, 22 hours, 25 hours, 28 hours, 30 hours, etc. It is understood that the reaction time may be other suitable selections within the range of 20 hours-30 hours.

[0026] It is understood that after the reaction solution is stirred at 20°C-30°C for 20h-30h, MIL-100 (Fe) can be obtained by filtering, washing, and drying. Washing can be performed with water.

[0027] Optionally, MIL-100(Fe) and the silver ion solution are mixed and stirred for 2-5 hours at a relatively high stirring speed, for example, 1000-1500 rpm. Furthermore, the stirring speed for mixing MIL-100(Fe) and the silver ion solution can be 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, etc. The stirring time can be 2 hours, 3 hours, 4 hours, 5 hours, etc.

[0028] Alternatively, after the MIL-100 (Fe) and silver ion solution are mixed and reacted, the chloride ion solution is added dropwise and stirred for 5-10 hours under natural light irradiation. The stirring speed can be 200-300 rpm. For example, the stirring speed can be 200 rpm, 220 rpm, 250 rpm, 280 rpm, 300 rpm, etc. The stirring time can be 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, etc.

[0029] It is understood that after mixing MIL-100 (Fe) with a silver ion solution, stirring for 2-5 hours, then adding a chloride ion solution dropwise, and stirring for 5-10 hours under natural light irradiation, the AgCl / MIL-100 (Fe) MOF material can be obtained by filtering, washing, and drying. Washing can be performed with water.

[0030] In S102 of the above embodiment, when the TiO2 ratio is less than 0.1, its ability to capture and transfer photogenerated electrons is limited, and the photocatalytic efficiency of the composite system does not significantly improve. As the TiO2 ratio increases to 0.5, the separation efficiency of photogenerated carriers significantly improves, but excessive TiO2 may block the light absorption of the AgCl / MIL-100(Fe)MOF material. Therefore, the mass ratio of the AgCl / MIL-100(Fe)MOF material to TiO2 is 1:(0.1-0.5).

[0031] When the mass ratio of AgCl / MIL-100 (Fe) MOF material to ZnO is 1: (1.2-2.5), it can form a good energy band match with AgCl / MIL-100 (Fe) MOF material and TiO2, broadening the light response range from the ultraviolet light region to the visible light region.

[0032] Optionally, the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO is 1:0.3:2.

[0033] The mixed system was stirred in the dark for 0.5-1 hour to allow for full contact and adsorption between the material and the water. After one hour of adsorption in the dark, the adsorption of tetracycline antibiotics on the material surface reached 70%-80% of the equilibrium adsorption capacity. A visible light source with an intensity of 50-200 mW / cm² was then used to initiate the photocatalytic reaction. At lower light intensities (e.g., 50 mW / cm²), the generation of photogenerated carriers is limited, resulting in a slow degradation rate. Increasing the light intensity to 200 mW / cm² increases the probability of recombination of photogenerated carriers.

[0034] Optionally, the stirring speed in the dark is 150 rpm-250 rpm. For example, the stirring speed in the dark can be 150 rpm, 180 rpm, 200 rpm, 220 rpm, 250 rpm, etc.

[0035] Optionally, the reaction temperature of the photocatalytic reaction is 20°C-30°C, and the reaction time is 1 hour-3 hours. The reaction temperature is controlled at 20°C-30°C. The effect of temperature on the photocatalytic reaction is primarily reflected in the reaction rate and material stability. At 20°C, the reaction rate is relatively slow, but the material stability is good. As the temperature rises to 30°C, the reaction rate accelerates, but excessively high temperatures may cause changes in the material structure, affecting its reusability. Under optimal conditions, the degradation rate of tetracycline antibiotics can reach over 95% with a reaction time of 1 hour-3 hours.

[0036] Optionally, the visible light source is a tungsten light source with a 400 nm cut-off filter.

[0037] Optionally, the molar concentration of silver ions in the silver ion solution is 50 mmol / L-60 mmol / L. For example, the molar concentration of silver ions in the silver ion solution can be 50 mmol / L, 52 mmol / L, 55 mmol / L, 58 mmol / L, 60 mmol / L, etc. Optionally, the silver ion solution is a silver nitrate solution.

[0038] Optionally, the molar concentration of chloride ions in the chloride ion solution is 10 mmol / L-15 mmol / L. For example, the molar concentration of chloride ions in the chloride ion solution can be 10 mmol / L, 12 mmol / L, 15 mmol / L, etc. Optionally, the chloride ion solution is a sodium chloride solution.

[0039] Optionally, the volume ratio of the silver ion solution to the chloride ion solution is 1:(3-5). For example, the volume ratio of the silver ion solution to the chloride ion solution can be 1:3, 1:4, 1:5, etc.

[0040] Optionally, the mass ratio of MIL-100 (Fe) to silver ions in the silver ion solution is 1:(1.1-1.3). For example, the mass ratio of MIL-100 (Fe) to silver nitrate in the silver ion solution can be 1:1.1, 1:1.2, 1:1.3, etc.

[0041] Example 1 The degradation method of tetracycline antibiotics in water in this embodiment is as follows: S101: Preparation of AgCl / MIL-100(Fe)MOF: 2.26g of FeCl₃・4H₂O and 1.676g of trimesic acid were dissolved in 120mL of deionized water. The pH was adjusted to 5 with 1mol / L sodium hydroxide solution. The mixture was stirred at 25°C for 24h, washed, and dried to obtain MIL-100(Fe). 0.2g of MIL-100(Fe) was added to 28mL of silver nitrate solution (molar concentration of silver nitrate, 53.7mmol / L) and stirred at 1500rpm for 3h. Then, 98mL of NaCl solution (molar concentration of sodium chloride, 10.48mmol / L) was added dropwise at a rate of approximately 10mL / min and stirred thoroughly under natural light for 8h. After repeated washing and drying overnight, the AgCl / MIL-100(Fe)MOF was obtained.

[0042] S102: Photocatalytic Degradation: AgCl / MIL-100(Fe)MOF material, TiO2, and ZnO were mixed with water containing tetracycline antibiotics in the dark. The mass ratio of AgCl / MIL-100(Fe)MOF material, TiO2, and ZnO was controlled to be 1:0.3:2. The mixture was stirred in the dark for 0.8 hours. Then, a tungsten lamp with a 400nm cutoff filter was used as the visible light source for the photocatalytic reaction. The light intensity of the light source was 100mW / cm². After the reaction, the concentration of tetracycline antibiotics in the water was determined by high-performance liquid chromatography, and the degradation rate was calculated to be 96%.

[0043] Example 2 Compared with Example 1, the difference of Example 2 is that the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in S102 is 1:0.1:1.2.

[0044] After the reaction, the concentration of tetracycline antibiotics in the water was determined by high performance liquid chromatography, and the degradation rate was calculated to be 88%.

[0045] Example 3 Compared with Example 1, the difference of Example 3 is that the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in S102 is 1:0.5:2.5.

[0046] After the reaction, the concentration of tetracycline antibiotics in the water was determined by high performance liquid chromatography, and the degradation rate was calculated to be 87%.

[0047] Example 4 Compared with Example 1, the difference of Example 4 is that the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in S102 is 1:0.1:2.5.

[0048] After the reaction, the concentration of tetracycline antibiotics in the water was determined by high performance liquid chromatography, and the degradation rate was calculated to be 91%.

[0049] Example 5 Compared with Example 1, the difference of Example 5 is that the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in S102 is 1:0.5:1.2.

[0050] After the reaction, the concentration of tetracycline antibiotics in the water was determined by high performance liquid chromatography, and the degradation rate was calculated to be 92%.

[0051] Comparative Example 1 The degradation method of tetracycline antibiotics in water in this comparative example includes: S101: Preparation of MIL-100 (Fe) MOF material: Dissolve 2.26 g of FeCl3・4H2O and 1.676 g of trimesic acid in 120 mL of deionized water, adjust the pH to 5 with 1 mol / L sodium hydroxide solution, stir at 25°C for 24 h, wash and dry to obtain MIL-100 (Fe) MOF material: Dissolve 2.26 g of FeCl3・4H2O and 1.676 g of trimesic acid in 120 mL of deionized water.

[0052] S102: Photocatalytic Degradation: MIL-100(Fe)MOF material, TiO2, and ZnO were mixed with water containing tetracycline antibiotics in the dark. The mass ratio of AgCl / MIL-100(Fe)MOF material, TiO2, and ZnO was controlled to be 1:0.3:2. The mixture was stirred in the dark for 0.8 hours. Then, a tungsten lamp with a 400nm cutoff filter was used as the visible light source for the photocatalytic reaction. The light intensity of the light source was 100mW / cm². After the reaction, the concentration of tetracycline antibiotics in the water was determined by high-performance liquid chromatography, and the degradation rate was calculated to be 61%.

[0053] Comparative Example 2 Compared with Example 1, the difference of Comparative Example 2 is that the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in S102 is 1:0:0.

[0054] After the reaction, the concentration of tetracycline antibiotics in the water was determined by high performance liquid chromatography, and the degradation rate was calculated to be 69%.

[0055] Comparative Example 3 Compared with Example 1, the difference of Comparative Example 3 is that the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in S102 is 1:0.05:1.

[0056] After the reaction, the concentration of tetracycline antibiotics in the water was determined by high performance liquid chromatography, and the degradation rate was calculated to be 74%.

[0057] Comparative Example 4 Compared with Example 1, the difference of Comparative Example 4 is that the mass ratio of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in S102 is 1:0.8:3.

[0058] After the reaction, the concentration of tetracycline antibiotics in the water was determined by high performance liquid chromatography, and the degradation rate was calculated to be 71%.

[0059] It can be seen from the examples and comparative examples that the synergistic combination of AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO in the present invention in an appropriate mass ratio can effectively improve the degradation rate of tetracycline antibiotics in water.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0061] For those skilled in the art, according to the concept of the present invention, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for degrading tetracycline antibiotics in water, characterized in that: The steps include: S101: Preparation of AgCl / MIL-100 (Fe) MOF material: Dissolving an iron ion source and trimesic acid in water, and adjusting the pH value to 4.5-5.5 to obtain a reaction solution; The reaction solution was stirred at 20°C-30°C for 20h-30h, and then washed and dried to obtain MIL-100 (Fe); The MIL-100 (Fe) was mixed with a silver ion solution, stirred for 2 h to 5 h, and then a chloride ion solution was added dropwise, and stirred for 5 h to 10 h under natural light irradiation conditions, and then washed and dried to obtain an AgCl / MIL-100 (Fe) MOF material; S102: Photocatalytic degradation: The AgCl / MIL-100 (Fe) MOF material, TiO2 and ZnO are mixed with water containing tetracycline antibiotics under dark conditions, and the mass ratio of the AgCl / MIL-100 (Fe) MOF material, the TiO2 and the ZnO is controlled to be 1: (0.1-0.5): (1.2-2.5). The mixed system is stirred in the dark for 0.5h-1h, and then a light source is turned on to carry out a photocatalytic reaction. The light source is a visible light source, and the light intensity of the light source is 50mW / cm²-200mW / cm².

2. The method for degrading tetracycline antibiotics in water according to claim 1, wherein: The reaction temperature of the photocatalytic reaction is 20° C.-30° C., and the reaction time is 1 h-3 h.

3. The method for degrading tetracycline antibiotics in water according to claim 1, wherein: The visible light source is a tungsten lamp with a 400nm cut-off filter.

4. The method for degrading tetracycline antibiotics in water according to any one of claims 1 to 3, characterized in that: The mass ratio of the AgCl / MIL-100 (Fe) MOF material, the TiO2 and the ZnO is 1:0.3:

2.

5. The method for degrading tetracycline antibiotics in water according to any one of claims 1 to 3, characterized in that: The molar ratio of the iron ions in the iron ion source to the trimesic acid is 1:(1.1-1.5).

6. The method for degrading tetracycline antibiotics in water according to claim 5, characterized in that: The iron ion source includes at least one of FeCl3·4H2O and Fe(NO3)3·9H2O.

7. The method for degrading tetracycline antibiotics in water according to any one of claims 1 to 3, characterized in that: The molar concentration of silver ions in the silver ion solution is 50 mmol / L-60 mmol / L.

8. The method for degrading tetracycline antibiotics in water according to any one of claims 1 to 3, characterized in that: The molar concentration of chloride ions in the chloride ion solution is 10 mmol / L-15 mmol / L.

9. The method for degrading tetracycline antibiotics in water according to any one of claims 1 to 3, characterized in that: The volume ratio of the silver ion solution to the chloride ion solution is 1:(3-5).

10. The method for degrading tetracycline antibiotics in water according to any one of claims 1 to 3, characterized in that: The mass ratio of the MIL-100 (Fe) to the silver ions in the silver ion solution is 1: (1.1-1.3).