Method and device for degrading tetracycline antibiotics in wastewater based on solar energy

Abstract

The present application belongs to the technical field of sewage treatment, and specifically discloses a treatment method and device for degrading tetracycline antibiotics in wastewater based on solar energy. The photo-thermal continuous flow reactor comprises a copper heat exchanger, the surface of the copper heat exchanger is coated with a heat-conducting material and a photo-thermal conversion material from inside to outside, and the copper heat exchanger is provided with a water inlet and a water outlet. The treatment method for degrading tetracycline antibiotics in wastewater utilizes the photo-thermal continuous flow reactor, and comprises the following steps: adding an oxidizing agent to wastewater containing tetracycline antibiotics, then introducing the copper heat exchanger from the water inlet; then irradiating the copper heat exchanger to perform degradation treatment; finally, discharging the degraded wastewater through the water outlet. The present application converts tetracycline antibiotics into copper complexes, not only reduces the dependence on temperature, but also improves the degradation efficiency, and realizes the continuous flow degradation of tetracycline antibiotics in wastewater based on solar energy.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a treatment method and apparatus for treating tetracycline antibiotics in wastewater based on solar energy degradation. Background Technology

[0002] Tetracycline, the first broad-spectrum antibiotic discovered by humans, is widely used globally due to its excellent antibacterial efficacy, low side effects, and affordability (Environmental Pollution, 2017, 221, 1-14). However, tetracycline antibiotics generally have low absorption rates in organisms, and the unmetabolized portion often enters natural water bodies through wastewater discharge. This not only disrupts the balance of aquatic ecosystems but also induces bacterial resistance, posing a serious threat to public health (Antibiotics, 2023, 12, 440). To address this issue, researchers have developed a series of technologies for degrading tetracycline antibiotics, mainly including physical, chemical, and biological methods. However, these methods all have certain limitations in practical applications. For example, traditional physical methods such as reverse osmosis generate large amounts of high-concentration wastewater during treatment, while sedimentation methods produce harmful sludge, making it difficult to achieve complete removal. Although biological methods can achieve complete degradation by culturing specific microorganisms, they require advanced operational techniques, have long treatment cycles, and lack stability, limiting their large-scale application. In contrast, advanced oxidation processes (AOPs), as a highly efficient, simple, and widely applicable chemical treatment method, have been widely used in the field of water treatment. This method involves adding an oxidant to wastewater and activating it to generate reactive oxygen species, thereby degrading pollutants into harmless substances. Among these, AOPs using sodium persulfate as an oxidant have attracted considerable attention due to their ease of storage, low cost, and excellent stability (Science of the Total Environment, 2022, 831, 154906).

[0003] In novel advanced oxidation methods based on sodium persulfate, activating persulfate ions to generate reactive oxygen species (ROS) is a crucial step, directly impacting the applicability and cost-effectiveness of the method. Existing activation methods include physical methods such as heating, ultrasonic treatment, light irradiation, and plasma activation, as well as chemical methods such as alkali activation, electrochemical activation, and catalytic activation (Science of the Total Environment, 2022, 831, 154906). Among these, thermal activation is particularly advantageous due to its simplicity and flexibility. Its principle involves breaking the oxygen-oxygen bonds in persulfate ions through heating, generating highly oxidizing sulfate radicals, which then transform into even more potent oxidizing hydroxyl radicals (Journal of Hazardous Materials, 2013, 254–255, 228–235). However, because the activation energy of the oxygen-oxygen bonds in sodium persulfate is as high as 140.16 kJ / mol, the system needs to be heated to 40–80 °C and maintained for 20–60 minutes for effective activation. This results in high energy consumption and is not conducive to continuous operation.

[0004] To address the high energy consumption of traditional thermal activation methods, researchers have explored converting solar energy, an economical and sustainable clean energy source, into thermal energy for the thermal activation process. While solar energy offers significant economic and environmental benefits, its low energy density and uneven distribution limit heating efficiency. Currently, advanced oxidative degradation schemes using solar thermal activation of sodium persulfate still require heating to 65°C for 4 hours followed by maintaining that temperature for 2 hours to achieve a 95% pollutant degradation efficiency (SolarEnergy, 2020, 205, 372–379). Therefore, developing a mature scheme for the continuous treatment of tetracycline-containing antibiotic wastewater based on solar energy remains a significant challenge.

[0005] Therefore, developing new and efficient technologies for the degradation of tetracycline antibiotics, especially innovative methods that combine solar energy utilization with chemical conversion, is of great significance for solving environmental pollution problems. Summary of the Invention

[0006] This invention addresses the technical problems of low efficiency and inability to operate continuously in the treatment of tetracycline antibiotics in wastewater using solar energy in existing technologies. It proposes a photothermal continuous flow reactor and a continuous flow treatment method for degrading tetracycline antibiotics in wastewater using solar energy.

[0007] The inventive concept of this invention is as follows: when tetracycline forms a complex with copper, due to the coordination of Cu... 2+Exhibiting strong electronegativity, the electron cloud density of tetracycline copper complexes is significantly higher than that of single tetracycline molecules. This makes the copper complexes more readily react with electrophilic sulfate or hydroxyl radicals, thus achieving effective degradation at lower temperatures. Simultaneously, the complexes formed between tetracycline antibiotics and copper can further react to generate cuprous ions, promoting bond breaking of the oxidant and generating reactive oxygen species through a Fenton-like reaction, increasing the activation pathway of the oxidant and improving degradation efficiency. Based on this, this invention converts tetracycline antibiotics into copper complexes to reduce the required heating temperature and improve degradation efficiency; and combines this with photothermal activation of sodium persulfate to achieve solar-driven, highly efficient, and continuous degradation of tetracycline antibiotics in wastewater.

[0008] First, solar energy is converted into heat energy using high-performance photothermal conversion materials, and then transferred to a copper heat exchanger via a thermally conductive material to heat the wastewater. During this process, thermally activated oxidants (such as sodium sulfate) generate reactive oxygen species (ROS), which initiate a degradation reaction with tetracycline antibiotics. Simultaneously, the tetracycline antibiotics react with divalent copper ions released from the copper heat exchanger to form copper complexes that are easily degraded by ROS. These copper complexes can effectively degrade even at relatively low temperatures, significantly reducing the temperature requirement. Furthermore, after forming a complex with copper, the tetracycline antibiotics can further react to generate cuprous ions, which further enhance the generation of ROS through a Fenton-like reaction, broadening the pathway for oxidant activation. Therefore, this invention, by converting tetracycline antibiotics into their copper complexes, not only reduces temperature dependence but also improves degradation efficiency, achieving continuous flow degradation of tetracycline antibiotics in wastewater based on solar energy.

[0009] To solve the above-mentioned technical problems, the first aspect of the present invention provides a photothermal continuous flow reactor, including a copper heat exchanger, wherein the surface of the copper heat exchanger is coated with a thermally conductive material and a photothermal conversion material from the inside to the outside, and the copper heat exchanger is provided with an inlet and an outlet.

[0010] In some embodiments of the present invention, the photothermal conversion material is selected from at least one of carbon black, activated carbon, graphite, and organic eutectic photothermal conversion materials.

[0011] In some embodiments of the present invention, the organic eutectic photothermal conversion material is formed by a combination of an electron donor and an electron acceptor, wherein the electron donor is N,N,N',N'-tetramethylbenzidine and the electron acceptor is tetracyano-p-quinone dimethylane. This organic eutectic photothermal conversion material exhibits good absorption performance in the 200-2500 nm wavelength range and can efficiently convert solar energy into thermal energy for activating oxidants.

[0012] In some embodiments of the present invention, the organic eutectic photothermal conversion material is prepared by a solvent method, including the following steps: first, N,N,N',N'-tetramethylbenzidine powder is dissolved in an organic solvent, then tetracyano-p-quinone dimethyl ether powder is added, and after ultrasonic-assisted dissolution, it is allowed to stand, separated, and dried to obtain the material.

[0013] In some embodiments of the present invention, the molar ratio of N,N,N',N'-tetramethylbenzidine to tetracyanoquinone dimethylane is (1-2):1.

[0014] In some embodiments of the present invention, the organic solvent includes acetone.

[0015] In some embodiments of the present invention, the settling time is 10-20 minutes, during which N,N,N',N'-tetramethylbenzidine and tetracyanoquinone dimethyl ether molecules in the solution precipitate out from the solution through non-covalent bond-driven self-assembly to form an organic eutectic.

[0016] In some embodiments of the present invention, the thermally conductive material is selected from at least one of thermally conductive silicone cloth, thermally conductive grease, and thermally conductive paste.

[0017] In some embodiments of the present invention, the lining or piping of the copper heat exchanger is made of metallic copper. Metallic copper is an ideal choice for heat exchanger materials due to its excellent thermal conductivity, low price, and ease of processing. Furthermore, tetracycline antibiotics can form copper complexes with divalent copper ions released from metallic copper. This is because Cu coordinated with tetracycline... 2+ The high electronegativity of tetracycline makes the electron cloud of its copper complex more concentrated than that of tetracycline, making it more likely to react with electrophilic sulfate or hydroxyl radicals. This not only enables effective degradation at lower temperatures, but also promotes the generation of cuprous ions through a Fenton-like reaction, further enhancing the reactive oxygen species generation pathway of the oxidant and improving degradation efficiency.

[0018] In some embodiments of the present invention, the copper heat exchanger is a plate radiator or a tubular radiator.

[0019] A second aspect of the present invention provides a continuous flow treatment method for degrading tetracycline antibiotics in wastewater, utilizing the above-mentioned photothermal continuous flow reactor, comprising the following steps:

[0020] (1) An oxidant is added to wastewater containing tetracycline antibiotics to obtain mixed wastewater; then the mixed wastewater is introduced into a copper heat exchanger from the inlet.

[0021] (2) Irradiate the copper heat exchanger to degrade it, and then discharge the degraded wastewater through the outlet.

[0022] In some embodiments of the present invention, the tetracycline antibiotics include one or more of tetracycline, oxytetracycline, and chlortetracycline.

[0023] In some embodiments of the present invention, the oxidant includes sodium persulfate, wherein the molar amount of sodium persulfate in the mixed wastewater is 4-24 times that of tetracycline antibiotics, preferably 8-20 times.

[0024] In some embodiments of the present invention, the illumination is continuous irradiation using sunlight.

[0025] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages:

[0026] (1) This invention employs advanced oxidation technology, which effectively degrades tetracycline antibiotics in wastewater by adding and activating an oxidant. Compared to physical methods such as reverse osmosis, ion exchange, and sedimentation, advanced oxidation not only achieves the complete degradation of tetracycline antibiotics but also avoids the generation of high-concentration wastewater and toxic sludge. Compared to biological methods such as constructing bioreactors and chemical methods such as electrocatalysis and photocatalysis, advanced oxidation has significant advantages due to its convenient operation, high efficiency, and wide applicability. Unlike methods that rely on electroactivation and photoactivation, this invention does not require the configuration of an electrolytic cell or artificial ultraviolet light source, simplifying the operation process. Furthermore, compared to alkaline activation and catalytic activation technologies, this invention does not require the introduction of external chemical reagents or materials, thereby eliminating the risk of secondary pollution.

[0027] (2) This invention utilizes solar energy for photothermal conversion, providing the necessary thermal energy to activate the oxidant for the degradation of tetracycline antibiotics. As a clean and renewable energy source, the application of solar energy significantly reduces energy consumption and costs compared to traditional heating methods that rely on electrical or chemical energy, while also improving environmental benefits.

[0028] (3) This invention utilizes a copper heat exchanger to introduce free divalent copper ions, which form easily degradable copper complexes with tetracycline antibiotics, thereby effectively reducing the required reaction temperature. Simultaneously, this treatment method expands the generation pathway of reactive oxygen species, further improving degradation efficiency. Compared with other advanced oxidation schemes that rely on photothermal activation of persulfate, this invention achieves a significant breakthrough in degradation efficiency, with a single-pass degradation rate for tetracycline antibiotics consistently above 99.47%, reaching a maximum of 99.82%. Furthermore, it can achieve continuous flow operation using solar energy, which has a relatively low energy density, opening up broad application prospects for the effective control and degradation of tetracycline antibiotic wastewater. Attached Figure Description

[0029] Figure 1 Here is a picture of a copper heat exchanger.

[0030] Figure 2 A schematic diagram (a) and a flowchart (b) of the preparation process of the photothermal continuous flow reactor are shown.

[0031] Figure 3 The absorption spectrum of the organic eutectic photothermal conversion material formed by N,N,N',N'-tetramethylbenzidine and tetracyano-p-quinone dimethane;

[0032] Figure 4 A schematic diagram of the treatment process for degrading tetracycline antibiotics in wastewater;

[0033] Figure 5 A physical diagram of an apparatus for degrading tetracycline antibiotics in wastewater;

[0034] Figure 6 The results of the experiment on the degradation of tetracycline in wastewater in Example 1;

[0035] Figure 7 The surface temperature distribution (a) and outlet temperature (b) of the photothermal continuous flow reactor in Example 1 are shown.

[0036] Figure 8 The experimental results (a) and outlet temperature (b) of the degradation of tetracycline in wastewater in Example 2 are shown.

[0037] Figure 9 The results of the experiment on the degradation of oxytetracycline in wastewater in Example 3;

[0038] Figure 10 Absorption spectra of tetracycline stock solution, tetracycline copper complex, and water sample after passing through a photothermal continuous flow reactor (a); and absorption spectra of tetracycline stock solution, water sample after passing through a photothermal continuous flow reactor, and water sample with added cuprous ion scavenger (b).

[0039] Figure 11 Electron spin resonance spectrum for capturing reactive oxygen species by adding DMPO. Detailed Implementation

[0040] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0041] The copper heat exchanger and photothermal continuous flow reactor used in the following embodiments of the present invention are as follows: Figure 1-2 As shown, where: Figure 1 The image shows a physical picture of a copper heat exchanger. This copper heat exchanger is a tubular copper heat exchanger that uses a hollow copper coil with a diameter of 2mm and an inner diameter of 1mm as the heat exchanger. The coil diameter is 7.5cm, the coil length is 1.8m, and the heat exchanger volume is 1.5mL.

[0042] Figure 2 The diagram shows the structure and preparation process of the photothermal continuous flow reactor, such as... Figure 2 As shown in (a), the photothermal continuous flow reactor includes a copper heat exchanger, and the surface of the copper heat exchanger is coated with a thermally conductive material and a photothermal (conversion) material sequentially from the inside to the outside. Its preparation process is as follows: Figure 2 As shown in (b): First, a thermally conductive material is uniformly covered on the surface of the copper heat exchanger, and then a powdered photothermal material is uniformly coated to obtain a photothermal continuous flow reactor.

[0043] The thermally conductive material consists of 0.15mm thick acrylic polymer and silicone thermally conductive double-sided adhesive; the photothermal material is an organic eutectic photothermal conversion material formed by N,N,N',N'-tetramethylbenzidine and tetracyanoquinone dimethylane, with a mass of 150mg.

[0044] The preparation process of organic eutectic photothermal conversion materials includes the following steps:

[0045] (1) Weigh 84.12 mg of N,N,N',N'-tetramethylbenzidine powder and dissolve it in 15 mL of acetone solution;

[0046] (2) Weigh 71.47 mg of tetracyanoquinone dimethyl ether powder and add it to the acetone solution of N,N,N',N'-tetramethylbenzidine prepared in step (1). Dissolve it completely under ultrasonic assistance to obtain a mixed solution.

[0047] (3) Let the mixed solution obtained in step (2) stand for 10-20 minutes. During this period, the two molecules in the solution form an organic eutectic through non-covalent bond-driven self-assembly and precipitate from the solution. Then, the precipitated organic eutectic is separated from the solution by vacuum filtration.

[0048] (4) Collect the filtered organic eutectic powder, let it stand, and allow the acetone to completely evaporate to obtain a dry organic eutectic photothermal conversion material formed by N,N,N',N'-tetramethylbenzidine and tetracyano-p-quinone dimethylane. This organic eutectic photothermal conversion material can effectively absorb light with wavelengths of 200-2500 nm (see...). Figure 3 (Wavelength represents wavelength, and Absorbance represents absorption rate), and the photothermal conversion efficiency under sunlight can reach 90%.

[0049] The following embodiments of the present invention describe a treatment process for the degradation of tetracycline antibiotics in wastewater using the aforementioned photothermal continuous flow reactor, such as... Figure 4 As shown, the process includes the following steps: First, wastewater containing tetracycline antibiotics and an oxidant is pumped into the inlet of the copper heat exchanger of a photothermal continuous flow reactor. Then, the photothermal continuous flow reactor is continuously exposed to sunlight for degradation. The degraded wastewater flows out from the outlet. The physical apparatus for degrading tetracycline antibiotics in the above-mentioned wastewater is shown below. Figure 5 As shown.

[0050] Example 1

[0051] use Figure 5 The apparatus shown treats tetracycline antibiotics in wastewater. In this embodiment, the tetracycline antibiotic in the wastewater is tetracycline with a concentration of 0.125 mmol / L (56 mg / L), and the added oxidant sodium persulfate has a concentration of 2 mmol / L, which is 16 equivalents of tetracycline.

[0052] In this embodiment, a controlled-flow syringe pump was used to deliver raw water containing the aforementioned concentrations of tetracycline and sodium persulfate to the photothermal continuous flow reactor at a flow rate of 1 mL / min. During the experimental investigation, an ultrafine thermocouple was used to measure the temperature of the treated water sample at the outlet. The photothermal continuous flow reactor was placed under sunlight, and the solar power density measured using a power meter was approximately 127 mW / cm². 2 The retention time of raw water in the photothermal continuous flow reactor was 1.5 min. Treated water samples were collected from the reactor every 5 min to determine the tetracycline concentration and calculate the degradation rate. The results are as follows: Figure 6 As shown. By Figure 6 It can be seen that in the water sample taken at 5 minutes after treatment, 87.96% of tetracycline had been degraded. After a brief equilibrium period, the single-pass degradation rate of tetracycline by the device stabilized at over 99.47%, reaching a maximum of 99.82%. Based on the retention time of 1.5 minutes, the pseudo-first-order reaction kinetic constant k for the degradation of tetracycline in water using this device under these operating conditions can be calculated to be 3.070 min. -1 .

[0053] Figure 7 The above figures represent the surface temperature of the photothermal continuous flow reactor, captured by a thermal imaging camera, and the temperature of the treated water sample at the outlet of the device, monitored using an ultrafine thermocouple, under the operating conditions of Example 1. Figure 7 It can be seen that the power density is approximately 127 mW / cm². 2Under sunlight, the surface temperature of the stabilized photothermal continuous flow reactor reached 71.4℃. At the outlet, the temperature of the treated water sample stabilized at approximately 64℃. This indicates that the organic eutectic photothermal conversion material formed from N,N,N',N'-tetramethylbenzidine and tetracyanoquinone dimethylane can effectively capture sunlight and efficiently convert it into heat energy. Simultaneously, the heat energy converted by the photothermal material can be conducted to the tetracycline water sample within the heat exchanger via thermally conductive double-sided adhesive tape and a tubular copper heat exchanger, effectively heating it to approximately 64℃.

[0054] Example 2

[0055] The conditions for degrading tetracycline antibiotics in water were followed as described in Example 1, except that the solar power density was measured to be approximately 60.8-73.6 mW / cm² during the experiment due to cloudy weather. 2 . Figure 8 The results of the experiment on the degradation of tetracycline in water under the conditions of Example 2, and the temperature of the treated water sample at the outlet of the device. Figure 8 It can be seen that under cloudy weather conditions, in the treated water sample taken at 5 minutes, tetracycline had degraded by 60.51%. After this brief equilibrium period, the single-pass degradation rate of tetracycline by the device stabilized at over 81.66%, reaching a maximum of 85.75%. At the device outlet, the temperature of the treated water sample stabilized at approximately 43℃. Based on a retention time of 1.5 minutes, the pseudo-first-order reaction kinetic constant k for the degradation of tetracycline in water under these operating conditions can be calculated as k = 1.299 min. -1 The above results demonstrate that even under conditions of low sunlight density, the treatment method of this invention can still efficiently degrade tetracycline.

[0056] Example 3

[0057] The conditions for degrading tetracycline antibiotics in water were the same as in Example 1, except that the solar power density was measured to be approximately 102 mW / cm² during the experiment. 2 The tetracycline antibiotic used was oxytetracycline, at a concentration of 0.125 mmol / L (57.5 mg / L). The degradation results were as follows... Figure 9 As shown, the single-pass degradation rate of tetracycline by the device is consistently above 76.03%, reaching a maximum of 76.41%. Based on a retention time of 1.5 min, the pseudo-first-order reaction kinetic constant k for the degradation of tetracycline in water using this device under these operating conditions can be calculated to be 0.963 min. -1 The above results demonstrate that the treatment method of the present invention can efficiently degrade oxytetracycline, one of the tetracycline antibiotics.

[0058] Comparative Examples 1-7

[0059] The pseudo-first-order reaction kinetic constants k for tetracycline antibiotics in wastewater treated using the methods described in Examples 1-3 were 3.070, 1.299, and 0.963 min, respectively. -1 (The larger the value, the faster the degradation). Comparative Examples 1-7 are tetracycline antibiotics in wastewater treated using existing technologies. Their pseudo-first-order reaction kinetic constants k are shown in Table 1.

[0060] Table 1: Comparison of k-values ​​of tetracycline antibiotics in wastewater treated by Examples 1-3 and Comparative Examples 1-7

[0061]

[0062]

[0063] As shown in Table 1, the pseudo-first-order reaction kinetic constant k of the method of the present invention for treating tetracycline antibiotics in wastewater is significantly greater than the k value of other prior art solutions in Comparative Examples 1-7 for treating tetracycline antibiotics in wastewater. That is, the method of the present invention is extremely efficient in treating tetracycline antibiotics in wastewater.

[0064] Verification Experiment

[0065] The method of this invention exhibits extremely high efficiency in treating tetracycline antibiotics in wastewater. This superior performance is primarily attributed to two key factors: first, the photothermal conversion material used efficiently captures solar energy and converts it into heat energy; second, tetracycline antibiotics can form copper complexes with divalent copper ions released from a copper heat exchanger. These copper complexes not only react more readily with reactive oxygen species (ROS), thus reducing the heating temperature required for degradation, but also further react to generate cuprous ions. These cuprous ions, through a Fenton-like reaction, further promote the generation of ROS by the oxidant, thereby increasing the pathway for oxidant activation and improving degradation efficiency. Therefore, these mechanisms work together to significantly enhance the efficiency of tetracycline antibiotic degradation.

[0066] 1. Formation of copper complexes and their role in lowering degradation temperature

[0067] This embodiment experimentally verifies the mechanism of the method of the present invention for treating tetracycline antibiotics in wastewater. The experiment was conducted according to the conditions of Example 1, the only difference being that the photothermal continuous flow reactor was not irradiated, therefore the degradation effect of tetracycline was not significant. Water samples were collected from the reactor outlet, and their ultraviolet absorption spectra were measured and compared with the absorption spectra of tetracycline stock solution and tetracycline copper complex. Figure 10As shown in Figure a, after flowing through the photothermal continuous flow reactor, the absorption spectrum of the water sample changed significantly compared to the tetracycline stock solution. Its characteristic absorption peak shifted significantly from 357 nm to 374 nm, which is very similar to the absorption spectrum of the tetracycline copper complex. This indicates that after flowing through the copper heat exchanger, tetracycline underwent a complexation reaction with divalent copper ions released from the copper heat exchanger, forming a tetracycline copper complex. Due to the coordination of Cu with tetracycline... 2+ Due to their strong electronegativity, the electron cloud of tetracycline's copper complex is more concentrated than that of tetracycline itself. Therefore, tetracycline's copper complex reacts more readily with electrophilic sulfate or hydroxyl radicals, enabling it to be effectively degraded at relatively lower temperatures, thus reducing the temperature requirement.

[0068] 2. The formation of cuprous ions and their role in improving degradation efficiency

[0069] Meanwhile, following the method reported in the literature (Journal of Hazardous Materials, 2022, 421, 126673), the generation of cuprous ions was confirmed by the formation of a yellow complex (with characteristic absorption at 457 nm) between 2,9-dimethyl-1,10-phenanthroline and cuprous ions. A methanol solution of 2,9-dimethyl-1,10-phenanthroline was added to a water sample flowing through a photothermal continuous flow reactor, and its ultraviolet absorption spectrum was measured. The results are as follows: Figure 10 As shown in b, the addition of a methanol solution of 2,9-dimethyl-1,10-phenanthroline resulted in a new absorption peak at 457 nm, confirming the formation of cuprous ions. This indicates that tetracycline first forms a tetracycline copper complex after flowing through the photothermal continuous flow reactor, and then further reacts to generate cuprous ions. These cuprous ions catalyze the breaking of the oxygen-oxygen bond in persulfate ions through a Fenton-like reaction, generating sulfate free radicals, which are used to degrade tetracycline antibiotics in wastewater, thereby improving the degradation efficiency.

[0070] 3. Copper promotes the formation of reactive oxygen species and improves degradation efficiency.

[0071] Following the method reported in the literature (Chemical Engineering Journal, 2023, 474, 145510), 5,5-dimethyl-1-pyrrolidone-N-oxide (DMPO) and electron spin resonance spectroscopy (EPR) were used to capture reactive oxygen species generated in the system. In the experiment, an aqueous solution of tetracycline copper complex and sodium persulfate was heated in a 50°C water bath to simulate the conditions in a photothermal continuous flow reactor. A control group containing only tetracycline and sodium persulfate was also set up. The experimental results are as follows: Figure 11As shown in the figure, the horizontal and vertical axes represent the magnetic field, and the vertical axis represents the intensity. When the system does not contain copper (such as...), Figure 11 As shown in a), when only tetracycline and sodium persulfate were present, no obvious EPR signal was observed after heating at 50°C for 15 minutes; however, when copper was introduced into the system (as shown in a), no obvious EPR signal was observed after heating at 50°C for 15 minutes; while when copper was introduced into the system (e.g., ... Figure 11 As shown in b), obvious DMPO-OH· and DMPO-SO4 could be detected after heating at 50℃ for only 3 minutes. ·- The signal indicates that the introduction of copper significantly promotes the formation of reactive oxygen species, thereby significantly improving the efficiency of degrading tetracycline antibiotics in wastewater.

[0072] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A photothermal continuous flow reactor, characterized in that, The device includes a copper heat exchanger, the surface of which is coated with a thermally conductive material and a photothermal conversion material from the inside out. The copper heat exchanger has an inlet and an outlet. The photothermal conversion material is an organic eutectic photothermal conversion material, which is formed by a combination of an electron donor and an electron acceptor. The electron donor is N,N,N',N'-tetramethylbenzidine, and the electron acceptor is tetracyanoquinone dimethylane.

2. The photothermal continuous flow reactor according to claim 1, characterized in that, The thermally conductive material is selected from at least one of thermally conductive silicone cloth, thermally conductive grease, and thermally conductive paste.

3. The photothermal continuous flow reactor according to claim 1, characterized in that, The lining or pipes of the copper heat exchanger are made of metallic copper.

4. The photothermal continuous flow reactor according to claim 1 or 3, characterized in that, The copper heat exchanger is a plate radiator or a tubular radiator.

5. A method for treating tetracycline antibiotics in wastewater, characterized in that, The process using the photothermal continuous flow reactor as described in any one of claims 1-4 includes the following steps: (1) An oxidant is added to wastewater containing tetracycline antibiotics to obtain mixed wastewater; then the mixed wastewater is introduced into a copper heat exchanger from the inlet. (2) Irradiate the copper heat exchanger to degrade it, and then discharge the degraded wastewater through the outlet.

6. The method for treating tetracycline antibiotics in wastewater according to claim 5, characterized in that, The tetracycline antibiotics include one or more of tetracycline, oxytetracycline, and chlortetracycline.

7. The method for treating tetracycline antibiotics in wastewater according to claim 5, characterized in that, The oxidant includes sodium persulfate, and in the mixed wastewater, the molar amount of sodium persulfate is 4-24 times that of tetracycline antibiotics.

8. The method for treating tetracycline antibiotics in wastewater according to claim 5, characterized in that, The illumination is continuous exposure to sunlight.

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