Method for degrading antibiotics in water based on vacuum ultraviolet rays

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a method for degrading antibiotics in water based on vacuum ultraviolet rays, which comprises the following steps: adding a sample water body containing antibiotics into a sample container of a photoreaction device, and starting a magnetic stirrer to uniformly mix liquid in the sample container under the action of rapid rotation of a magnetic stirring rotor; adding a Fenton reagent into the sample container to enable the sample water body to reach a preset reaction condition; the peristaltic pump is opened, and the reaction liquid in the sample container is pumped into the annular reaction layer under the action of the peristaltic pump and reacts under the irradiation of the detachable vacuum ultraviolet light source so as to degrade antibiotics in the sample water body.

Description

Technical Field

[0001] The present application belongs to the technical field of water treatment, and specifically relates to a method for degrading antibiotics in water based on vacuum ultraviolet rays. Background Art

[0002] In the past few decades, antibiotics frequently detected in the environment have attracted widespread attention for the serious threat they pose to the ecological safety of water bodies. At present, antibiotics are mainly discharged into the water environment through multiple sources such as municipal sewage treatment plants, centralized livestock farms, hospitals, pharmaceutical factories and chemical plants. Since most antibiotics are highly water-soluble and chemically stable, it is difficult for traditional water treatment technologies to effectively remove them.

[0003] The development of efficient treatment technologies is particularly important for achieving effective removal of antibiotics in aquatic environments and thus reducing their harm to the aquatic environment and human health. Advanced oxidation technologies (AOPs) are efficient water treatment technologies that can generate high redox potential and strong oxidizing HO in situ. ● , thereby removing difficult-to-degrade organic pollutants in water bodies. Summary of the invention

[0004] The present application provides a method for degrading antibiotics in water based on vacuum ultraviolet rays, which can solve the problem in the prior art that traditional water treatment technology is difficult to effectively remove antibiotics.

[0005] The present application provides a method for degrading antibiotics in water based on vacuum ultraviolet light, comprising:

[0006] Add the sample water containing antibiotics into the sample container of the photoreaction device, turn on the magnetic stirrer, and make the liquid in the sample container evenly mixed under the action of the rapid rotation of the magnetic stirring rotor;

[0007] Add Fenton reagent into the sample container so that the sample water reaches the preset reaction conditions;

[0008] The peristaltic pump is turned on, and the reaction liquid in the sample container is pumped into the annular reaction layer under the action of the peristaltic pump, and reacts under the irradiation of a detachable vacuum ultraviolet (VUV) light source to degrade the antibiotics in the sample water;

[0009] The photoreaction device comprises: a photoreactor, a liquid circulation system and a constant temperature water bath layer; the photoreactor comprises: a detachable VUV light source, a high-purity quartz annular reaction layer, a top cover body and a bottom cover body; the top and bottom of the photoreactor are respectively provided with a top cover body and a bottom cover body, and a detachable VUV light source is vertically provided in the photoreactor; the detachable VUV light source is detachably fixed to the top cover body; a constant temperature water bath layer is sleeved on the outer side of the photoreactor; the liquid circulation system comprises: a magnetic stirrer, a liquid outlet pipe, a liquid return pipe and a sample container, one end of the liquid outlet pipe is connected to the sample container, the other end of the liquid outlet pipe is detachably connected to the high-purity quartz annular reaction layer, one end of the liquid return pipe is connected to the sample container, and the other end of the liquid return pipe is detachably connected to the high-purity quartz annular reaction layer; the magnetic stirrer is used to place the sample container, a magnetic stirring rotor is placed in the sample container, and a peristaltic pump is connected to the middle part of the liquid outlet pipe.

[0010] Optionally, the Fenton reagent is FeCl3·6H2O and H2O2.

[0011] Optionally, the method further comprises:

[0012] The initial pH was adjusted using 0.1 M NaOH and HCl, and the initial pH value of the sample water was 4.0.

[0013] Optionally, the method further comprises:

[0014] After adjusting the initial pH, add the following compounds:

[0015] Sodium salts, as donors of inorganic anions (IAs), include: NaNO3, NaHCO3 and NaCl;

[0016] Humic acid (HA), as a natural organic matter donor;

[0017] tert-Butanol, as a hydroxyl radical (HO ● ) of a quencher;

[0018] p-Benzoquinone, as a hydroperoxide radical (HO2 ● ) of a quencher;

[0019] 5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) and 5-tert-butyl-5-methyl-1-pyrroline-N-oxide (BMPO) as spin trapping agents for free radicals.

[0020] Optionally, the method further comprises:

[0021] Reaction samples were collected at set time intervals, and excess NaHSO3 was quickly added to the reaction sample solution to eliminate the residual oxidant.

[0022] Optionally, the method further comprises:

[0023] Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS / MS) analysis was used to determine the concentration of sulfadimethoxine (SMN);

[0024] The mobile phase was a mixture of 0.2% formic acid solution (65%) and acetonitrile (35%); the flow rate was 0.3 mL / min, the column temperature was 30°C, and the injection volume was 5 μL; the mass spectrometry adopted positive ion electrospray ionization mode, and the detection m / z were 279.3, 92.0 and 186.0, respectively; the SMN retention time was 1.32 min, and the quantification limit was 1.80 nM.

[0025] Optionally, the method further comprises:

[0026] The Fe 2+ The detection wavelength was 510 nm.

[0027] Optionally, the method further comprises:

[0028] Electron paramagnetic resonance spectroscopy was used to measure the free radical concentration; free radicals included: HO ● HO2 ● , DMPO spin traps and BMPO spin traps;

[0029] In the determination process, DMPO and BMPO were used as spin trapping agents; the test temperature was 25°C, the microwave frequency was 9.8 GHz, and the modulation frequency was 100 kHz;

[0030] The central magnetic field of the DMPO system is 3509.76G, and that of the BMPO system is 3503.39G.

[0031] Optionally, the method further comprises:

[0032] According to the measured SMN concentration, the degradation kinetic curve was analyzed and obtained.

[0033] Optionally, before adding the sample water containing the antibiotic into the sample container of the photoreaction device, the method further comprises:

[0034] Installing a detachable VUV light source to the photoreaction device; the detachable light source is a detachable VUV light source;

[0035] Turn on the cooling circulator, pump ultrapure water into the constant temperature water bath through the cooling water inlet and discharge it back through the cooling water outlet;

[0036] Turn on the detachable VUV light source of the photoreaction device to preheat the irradiation chamber;

[0037] Open the high-purity nitrogen gas storage cylinder, and continuously introduce high-purity nitrogen into the irradiation chamber through the high-purity nitrogen gas inlet and discharge it from the high-purity nitrogen gas exhaust port, so that the irradiation chamber is filled with high-purity nitrogen.

[0038] Optionally, the water temperature of the thermostatic water bath is kept constant at 25°C.

[0039] In the embodiment of the present application, a sample water body containing antibiotics is added to a sample container of a photoreaction device, and a magnetic stirrer is turned on so that the liquid in the sample container is evenly mixed under the action of the rapid rotation of the magnetic stirring rotor; a Fenton reagent is added to the sample container so that the sample water body reaches a preset reaction condition; a peristaltic pump is turned on, and the reaction liquid in the sample container is pumped into the annular reaction layer under the action of the peristaltic pump, and reacts under the irradiation of a detachable VUV light source to degrade the antibiotics in the sample water body; because the production and maintenance costs of the VUV light source are similar to those of a traditional low-pressure (LP) mercury lamp, more strongly oxidizing HO can be generated in situ without increasing the cost. ● , thereby accelerating the removal of refractory organic pollutants in water bodies and achieving cost reduction and efficiency improvement. Through the action of Fenton reagent and VUV light source, Fe 3+ The complex is Fe 2+ , promoting the generation of active oxygen species and inhibiting the precipitation of iron, thereby accelerating the degradation of pollutants and reducing the generation of sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic structural diagram of a photoreaction device provided in an embodiment of the present application;

[0041] Figure 2 is a SMN morphology distribution diagram provided in an embodiment of the present application;

[0042] Figure 3 This is a degradation kinetics curve diagram provided in the examples of the present application. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0044] The embodiments of the present application can be applied to at least the following scenarios, which are described in detail below:

[0045] In the past few decades, antibiotics frequently detected in the environment have attracted widespread attention as a serious threat to the ecological safety of water bodies. At present, antibiotics are mainly discharged into the water environment through multiple sources such as municipal sewage treatment plants, centralized livestock farms, hospitals, pharmaceutical factories and chemical plants. Since most antibiotics (such as sulfonamides and fluoroquinolone antibiotics) are highly water-soluble and chemically stable, it is difficult to effectively remove them using traditional water treatment technologies (such as coagulation-flocculation, adsorption and precipitation).

[0046] As a typical sulfonamide antibiotic, SMN has the advantages of a wide antibacterial spectrum, strong bactericidal power, and low price. Since SMN is widely used to treat human and animal diseases, it can be detected in many water environments around the world, with concentrations reaching ng / L-μg / L. So far, although no research has reported that SMN will have obvious toxic side effects on human health, some scholars have found that its long-term use will lead to high bacterial resistance and potential bioaccumulation and persistence. Therefore, the development of efficient treatment technology is particularly important to achieve the effective removal of antibiotics in the water environment, thereby reducing its harm to the water environment and human health.

[0047] AOPs is a highly efficient water treatment technology that can generate high redox potential and strong oxidizing HO in situ. ● As a widely used AOP, photo-Fenton technology (λ<400nm) can reduce Fe 3+ The complex is Fe 2+ , thereby promoting the generation of reactive oxygen species (ROSs) and inhibiting the precipitation of iron. The main chemical reactions involved in the photo-Fenton technology are shown in equations 1-6:

[0048] Fe 2+ +H2O2→Fe 3+ +HO · +OH - (1)

[0049] Fe 3+ +H2O2→Fe 2+ +HO2 · +H + (2)

[0050] HO2 · +Fe 3+ →Fe 2+ +O2+H + (3)

[0051] HO · +Fe 2+ →Fe 3+ +OH- (4)

[0052] HO · +H2O2→HO2 · +H2O (5)

[0053] [Fe(OH)] 2+ +hv <400 →Fe 2+ +HO · (6)

[0054] Since H2O can be photolyzed by VUV to generate HO ● , hydrogen radical (H ● ) and hydrated electrons As shown in Equations 7-8, VUV is therefore also considered to be an AOP that can remove organic pollutants in water.

[0055] H2O+hv 185 →HO · +H · (7)

[0056]

[0057] As the most common ultraviolet (UV) light source, LP mercury lamp can simultaneously emit 185nm and 254nm photons (i.e. VUV / UV), thereby directly photolyzing and indirectly oxidizing organic pollutants in water. When the detachable VUV light source replaces the traditional UV mercury lamp as the light source, VUV / UV / chlorine has a higher efficiency in removing organic pollutants than UV / chlorine technology, which is mainly due to the additional HO ● The generation and synergistic effects are jointly led to.

[0058] Therefore, VUV / UV can be used as an efficient light source for UV-based AOPs (UV-AOPs). At present, there are relatively few studies on VUV / UV / Fenton (VPF) technology in the field of water treatment, so it is very meaningful to explore its removal of organic pollutants in water.

[0059] In order to facilitate the explanation of the vacuum ultraviolet degradation method of antibiotics in water provided by the present application, the photoreaction device used in the method of the present application is described below:

[0060] like Figure 1 As shown, this embodiment provides a light reaction device, including:

[0061] Photoreactor 10, liquid circulation system 20 and constant temperature water bath layer 30;

[0062] The photoreactor 10 includes: a detachable VUV light source 11, a high-purity quartz annular reaction layer 12, a top cover 13, and a bottom cover 14;

[0063] A top cover 13 and a bottom cover 14 are respectively arranged at the top and bottom of the photoreactor 10, and a detachable VUV light source 11 is vertically arranged in the photoreactor; the detachable VUV light source 11 is detachably fixed to the top cover 13;

[0064] The outer side of the photoreactor is provided with a constant temperature water bath layer 30;

[0065] The liquid circulation system 20 includes: a liquid outlet pipe 21, a liquid return pipe 22 and a sample container 23. One end of the liquid outlet pipe 21 is connected to the sample container 23, and the other end of the liquid outlet pipe 21 is detachably connected to the high-purity quartz annular reaction layer 12. One end of the liquid return pipe 22 is connected to the sample container 23, and the other end of the liquid return pipe 22 is detachably connected to the high-purity quartz annular reaction layer 12.

[0066] The detachable VUV light source 11 refers to a light source inside the photoreactor that can be easily disassembled and replaced, such as a UV lamp or an LED lamp, etc., which is convenient for maintenance and optimization of the light source and improves the flexibility and adaptability of the system.

[0067] The high-purity quartz annular reaction layer 12 is the main reaction area for placing photocatalysts or samples inside the photoreactor 10. The light emitted by the detachable VUV light source 11 irradiates the high-purity quartz annular reaction layer 12 to stimulate the photocatalytic reaction or directly act on the sample.

[0068] In the embodiment of the present application, on the one hand, the high-purity quartz annular reaction layer 12 can make the structure of the entire photoreaction device more compact and stable, which can not only reduce the volume of the photoreaction device, but also facilitate the transportation of the device and extend the service life of the photoreaction device.

[0069] On the other hand, compared with traditional high-purity quartz capillary tubes, the volume of the high-purity quartz annular reaction layer is significantly larger, which can increase the irradiation area of ​​the light source and the utilization efficiency of photons, reduce the cost of sewage treatment, and improve the efficiency of sewage treatment.

[0070] In addition, the high-purity quartz annular reaction layer can increase the amount of wastewater treated in a single test, so that each sampling in the detection process has little or even negligible impact on the total volume of the reaction solution, ensuring the scientificity and accuracy of the experimental results.

[0071] Furthermore, the high-purity quartz annular reaction layer can significantly increase the amount of wastewater treated per unit time, laying a good foundation for the practical promotion and application of related water treatment technologies in the future.

[0072] The top cover and bottom cover refer to the closed covers at the upper and lower ends of the photoreactor, which play the role of sealing the internal environment of the reactor and controlling the temperature and other conditions.

[0073] The detachable VUV light source and the top cover body are detachably fixed, which means that the light source, reaction layer and other components are detachably connected to the cover body, so that it is convenient to open the photoreactor to perform operations such as light source maintenance.

[0074] In the embodiments of the present application, the annular reaction interlayer structure is stable, and the switching and updating of different detachable VUV light sources can be easily achieved. By comparing the treatment effects of pollutants under different light sources, the mechanism can be explored.

[0075] The constant temperature water bath layer is a temperature-controlled water bath system arranged outside the photoreactor. Through the constant temperature water bath layer, the temperature conditions inside the reactor can be accurately controlled.

[0076] The liquid circulation system is a circulating flow system composed of a liquid outlet pipe, a liquid return pipe and a sample container, which can realize the continuous circulation of the reaction liquid between the reaction layer and the collection container, thereby improving the throughput of sample processing.

[0077] A high-purity nitrogen inlet pipe 15 and a high-purity nitrogen exhaust pipe 16 are respectively arranged on the photoreactor. The high-purity nitrogen inlet pipe 15 is connected to a high-purity nitrogen bottle, and the high-purity nitrogen exhaust pipe 16 is connected to the outside air.

[0078] The photoreactor is equipped with the following two nitrogen pipelines:

[0079] The high-purity nitrogen gas inlet pipe 15 is connected to the high-purity nitrogen gas bottle, and high-purity nitrogen gas can be introduced into the interior of the photoreactor through the high-purity nitrogen gas inlet pipe 15.

[0080] The high-purity nitrogen exhaust pipe 16 is connected to the outside air. Through the high-purity nitrogen exhaust pipe 16, the gas inside the photoreactor can be discharged into the outside air.

[0081] By continuously supplying high-purity nitrogen into the reactor, active gases such as oxygen in the air can be removed, providing a reaction environment and supporting the reaction process.

[0082] The middle part of the liquid outlet pipe is connected with a peristaltic pump 24, and the flow rate of the peristaltic pump is 600-1200 mL / min.

[0083] The peristaltic pump 24 can accurately control the flow rate of the liquid outlet to meet the liquid delivery requirements during the reaction process. The working principle of the peristaltic pump 24 is to produce a continuous, pulsation-free delivery effect by squeezing the hose through the roller, which can maintain the stable flow of the liquid in the liquid outlet pipe and avoid fluctuations in the flow rate, which is conducive to the smooth progress of the reaction process.

[0084] When the pressure in the reactor changes, the peristaltic pump 24 can prevent the liquid from flowing back into the reactor, thereby ensuring the stability of the reaction process. As an intermediate component of the liquid outlet pipe 21, the peristaltic pump 24 can be easily maintained and replaced, thereby improving the reliability of the entire system.

[0085] Wherein, the liquid circulation system 20 further includes:

[0086] The magnetic stirrer 25 is used to place the sample container 23 , and a magnetic stirring rotor is placed in the sample container 23 .

[0087] The magnetic stirrer 25 generates a controllable magnetic field to drive the magnetic stirring rotor inside the container to rotate, thereby achieving continuous stirring of the substances inside the sample container and increasing the contact and mixing between the reactants.

[0088] The sample container 23 is used to hold the raw materials or reactants that need to undergo photoreaction, and a magnetic stirring rotor is placed inside the container 23. When the magnetic stirring rotor is placed inside the sample container, it will rotate under the action of the external magnetic stirrer, thereby driving the reactants inside the container to mix.

[0089] Among them, a water outlet and a water inlet are respectively arranged at the top and bottom of the constant temperature water bath layer. The water outlet of the constant temperature water bath layer is connected to the water inlet of the cooling circulator through an outlet pipe, and the water outlet of the cooling circulator is connected to the water inlet of the constant temperature water bath layer through an inlet pipe.

[0090] The constant temperature water bath layer can maintain a constant temperature inside the water bath layer through continuous water inlet and outlet, providing a stable temperature environment for the photoreaction process. The outlet pipe and the inlet pipe form a closed circulating water circuit, connecting the constant temperature water bath layer with the cooling circulator. The cooling circulator can control the temperature of the circulating water and feed it back to the constant temperature water bath layer to maintain a constant temperature condition inside the photoreactor.

[0091] The coordinated work of the constant temperature water bath layer, circulation pipeline and cooling circulator provides precise temperature control for the photoreaction process, ensuring that the reaction can proceed at the optimal temperature.

[0092] The following is a description of a method for degrading antibiotics in water based on vacuum ultraviolet light provided in this application:

[0093] First, prepare the experimental materials:

[0094] All chemicals were of reagent grade or above and were not further purified before use. All solutions were prepared with ultrapure water (resistivity > 18.2 MΩcm).

[0095] Optionally, the Fenton reagent is FeCl3·6H2O and H2O2.

[0096] Optionally, the method further comprises:

[0097] The initial pH was adjusted using 0.1 M NaOH and HCl, and the initial pH value of the sample water was 4.0.

[0098] The initial pH of the solution was adjusted with 0.1 M NaOH and HCl.

[0099] Optionally, the method further comprises:

[0100] After adjusting the initial pH, add the following compounds:

[0101] Sodium salts, as donors of IAs, include: NaNO3, NaHCO3 and NaCl;

[0102] HA, as a natural organic matter donor;

[0103] tert-Butanol, as HO ● quencher;

[0104] p-Benzoquinone, as HO2 ● quencher;

[0105] DMPO and BMPO, as spin traps for free radicals.

[0106] Sodium salts (NaNO3, NaHCO3 and NaCl) and HA were used as donors of IAs and natural organic matter, respectively.

[0107] Tert-butyl alcohol (TBA) and p-benzoquinone (BQ) were used as HO ● and HO2 ● As spin trapping agents for free radicals, DMPO and BMPO and their stock solutions were stored at -18°C for future use.

[0108] Optionally, the method further comprises:

[0109] Reaction samples were collected at set time intervals, and excess NaHSO3 was quickly added to the reaction sample solution to eliminate the residual oxidant.

[0110] NaHSO3 is used to eliminate the residual oxidant after the Fenton reaction.

[0111] Chromatographic grade acetonitrile, methanol and formic acid were used as mobile phases for ultra-performance liquid chromatography-tandem mass spectrometry analysis.

[0112] The chemical structure of SMN is shown below. The chemical molecular formula is C 12 H 14 N4O2S, molecular weight is 278.33, morphological distribution is as follows Figure 2 shown.

[0113]

[0114] Next, the formal experimental part:

[0115] Add the sample water containing antibiotics into the sample container of the photoreaction device, turn on the magnetic stirrer, and make the liquid in the sample container evenly mixed under the action of the rapid rotation of the magnetic stirring rotor;

[0116] Add Fenton reagent into the sample container so that the sample water reaches the preset reaction conditions;

[0117] The peristaltic pump is turned on, and the reaction liquid in the sample container is pumped into the high-purity quartz annular reaction layer under the action of the peristaltic pump, and reacts under the irradiation of the detachable VUV light source to degrade the antibiotics in the sample water.

[0118] The preset reaction condition is that the initial pH value of the sample water is 4.0.

[0119] Because the production and maintenance costs of a detachable VUV light source are similar to those of a traditional LP mercury lamp, VPF can generate more high redox potentials in situ without increasing costs. Strong oxidizing HO ● , thereby accelerating the removal of difficult-to-degrade organic pollutants in water bodies and achieving cost reduction and efficiency improvement. Among them, VPF technology is an advanced oxidation technology that combines UV and Fenton reaction, mainly used for water treatment and wastewater treatment, especially for the degradation of organic pollutants.

[0120] VPF can reduce Fe 3+ The complex is Fe 2+ , promoting the generation of ROSs and inhibiting the precipitation of iron, thereby accelerating the degradation of pollutants and reducing the generation of sludge.

[0121] In the embodiment of the present application, a sample water body containing antibiotics is added to a sample container of a photoreaction device, and a magnetic stirrer is turned on so that the liquid in the sample container is evenly mixed under the action of the rapid rotation of the magnetic stirring rotor; Fenton reagent is added to the sample container so that the sample water body reaches a preset reaction condition; a peristaltic pump is turned on, and the reaction liquid in the sample container is pumped into the annular reaction layer under the action of the peristaltic pump, and reacts under the irradiation of a detachable VUV light source to degrade the antibiotics in the sample water body; because the production and maintenance costs of the VUV light source are similar to those of a traditional LP mercury lamp, more strongly oxidizing HO can be generated in situ without increasing the cost. ● , thereby accelerating the removal of refractory organic pollutants in water bodies and achieving cost reduction and efficiency improvement. Through the action of Fenton reagent and VUV light source, Fe 3+ The complex is Fe 2+, promoting the generation of active oxygen species and inhibiting the precipitation of iron, thereby accelerating the degradation of pollutants and reducing the generation of sludge.

[0122] Optionally, before adding the sample water containing the antibiotic into the sample container of the photoreaction device, the method further comprises:

[0123] Installing a detachable VUV light source to the photoreaction device; the detachable light source is a detachable VUV light source;

[0124] Turn on the cooling circulator, pump ultrapure water into the constant temperature water bath through the cooling water inlet and discharge it back through the cooling water outlet;

[0125] Turn on the detachable VUV light source of the photoreaction device to preheat the irradiation chamber;

[0126] Open the high-purity nitrogen gas storage cylinder, and continuously introduce high-purity nitrogen into the irradiation chamber through the high-purity nitrogen gas inlet and discharge it from the high-purity nitrogen gas exhaust port, so that the irradiation chamber is filled with high-purity nitrogen.

[0127] Optionally, the water temperature of the thermostatic water bath is kept constant at 25°C.

[0128] Among them, a water outlet and a water inlet are respectively arranged at the top and bottom of the constant temperature water bath layer. The water outlet of the constant temperature water bath layer is connected to the water inlet of the cooling circulator through an outlet pipe, and the water outlet of the cooling circulator is connected to the water inlet of the constant temperature water bath layer through an inlet pipe.

[0129] The constant temperature water bath layer can maintain a constant temperature inside the water bath layer through continuous water inlet and outlet, providing a stable temperature environment for the photoreaction process. The outlet pipe and the inlet pipe form a closed circulating water circuit, connecting the constant temperature water bath layer with the cooling circulator. The cooling circulator can control the temperature of the circulating water and feed it back to the constant temperature water bath layer to maintain a constant temperature condition inside the photoreactor.

[0130] The coordinated work of the constant temperature water bath layer, circulation pipeline and cooling circulator provides precise temperature control for the photoreaction process, ensuring that the reaction can proceed at the optimal temperature.

[0131] Optionally, the method further comprises:

[0132] The SMN concentration was determined by UPLC-MS / MS analysis;

[0133] The mobile phase was a mixture of 0.2% formic acid solution (65%) and acetonitrile (35%); the flow rate was 0.3 mL / min, the column temperature was 30°C, and the injection volume was 5 μL; the mass spectrometry adopted positive ion electrospray ionization mode, and the detection m / z were 279.3, 92.0 and 186.0, respectively; the SMN retention time was 1.32 min, and the quantification limit was 1.80 nM.

[0134] Optionally, the method further comprises:

[0135] The Fe 2+ The detection wavelength was 510 nm.

[0136] Phenomenal spectrophotometry is a spectrophotometric method based on the formation of complexes, which can determine the Fe 2+ The concentration of Fe 2+ It forms a purple complex with o-phenanthroline, which has a characteristic absorption peak at 510nm. By measuring the absorbance of the solution at 510nm, the Fe 2+ This is a simple and rapid method for the determination of Fe 2+ Detection method.

[0137] Optionally, the method further comprises:

[0138] Electron paramagnetic resonance spectroscopy was used to measure the free radical concentration; free radicals included: HO ● HO2 ● , DMPO spin traps and BMPO spin traps;

[0139] In the determination process, DMPO and BMPO were used as spin trapping agents; the test temperature was 25°C, the microwave frequency was 9.8 GHz, and the modulation frequency was 100 kHz;

[0140] The central magnetic field of the DMPO system is 3509.76G, and that of the BMPO system is 3503.39G.

[0141] Electron paramagnetic resonance (ESR) technology can detect and quantify the concentration of free radicals in solution. The free radicals measured include HO ● HO2 ● As well as spin traps formed by two spin trapping agents, DMPO and BMPO, and free radicals.

[0142] The test was carried out at 25°C, with a microwave frequency of 9.8 GHz and a modulation frequency of 100 kHz, and a stable ESR signal can be obtained. The central magnetic field of the DMPO system is 3509.76 G, and that of the BMPO system is 3503.39 G, which correspond to the characteristic peaks of different free radicals. By analyzing the ESR spectrum, the concentration changes of various free radicals can be quantitatively analyzed.

[0143] Optionally, the method further comprises:

[0144] According to the measured SMN concentration, the degradation kinetic curve was analyzed and obtained.

[0145] After determining the SMN concentration, we can draw a curve of SMN change over time, that is, the degradation kinetic curve. This can reflect the stability and degradation process of SMN under experimental conditions, which is very helpful for studying the dynamic behavior of SMN. The kinetic curve can be used to calculate the half-life, rate constant and other kinetic parameters of SMN, which is very important for the stability evaluation of SMN.

[0146] The degradation kinetics of SMN in UV, VUV / UV, Fenton (DF), UV-Fenton (UPF) and VPF techniques at an initial solution pH of 4.0 are shown in Figure 2. Figure 3 As shown in the figure, DF technology only corresponds to the horizontal axis "t(s)", while other technologies correspond to all horizontal axes. The pH of the solution dropped by less than 0.2 units before and after the reaction, which shows that SMN is mainly in the neutral state (SMN) during the entire reaction process. 0 )exist.

[0147] The degradation of SMN by different technologies conformed to the pseudo-first-order reaction kinetics well, and the fitting coefficient (R 2 ) is greater than 0.95, where k represents the degradation rate constant. Figure 3 It can be seen that the degradation effects of UV and DF technologies on SMN are poor (k UV =37.8m 2 einstein -1 , k DF =8.5×10 -4 s -1 ), the degradation rate was only 7% and 39% after 10 min reaction. Since most of the VUV photons emitted by the LP mercury lamp will be absorbed by H2O (about 55.6M) in the SMN solution, the VUV photolysis of SMN can be ignored.

[0148] After HO absorbs VUV photons with high energy, a chain reaction occurs (Equations 7, 8, 9-16) to generate a large amount of highly oxidizing HO ● and HO2 ● / O2 ●- , thereby accelerating the degradation of SMN (k VUV / UV =2094m 2 einstein -1 ), the degradation rate was as high as 96% after 10 minutes of reaction. In addition, compared with UV and VUV / UV technology, the degradation rate of SMN in UPF and VPF technology increased by 896 and 1804 m / s, respectively. 2 einstein -1 , the degradation rates increased by 75% and 3% respectively.

[0149] H · +O2→HO2 · (9)

[0150]

[0151] HO · +HO · →H2O2 (11)

[0152] HO · +HO2 · →H2O+O2 (12)

[0153] HO · +O2 ·- +H + →H2O+O2 (13)

[0154] HO2 · +HO2 · →H2O2+O2 (14)

[0155] HO2 · +O2 ·- +H + →H2O2+O2 (15)

[0156] H2O2+hv 185 / 254 →2HO · (16)

[0157] Theoretically, the degradation rate of SMN in VPF technology (k VPF ) should be equal to its VUV / UV(k VUV / UV ) and UPF(k UPF ) technology. However, the experimental results found that k VPF It is k VUV / UV and k UPF This indicates that VPF technology has a synergistic effect on the degradation of SMN. Compared with traditional UPF technology, the faster degradation of SMN in VPF technology is mainly attributed to the following two points:

[0158] First, VUV photons can split H2O and H2O2 to generate more ROSs;

[0159] Second, VUV photons can accelerate Fe 3+ / Fe 2+ Redox cycle.

[0160] Among them, the second point is the main reason why VPF technology significantly enhances SMN degradation.

[0161] Optionally, after the reaction is completed, the solution in the annular reaction layer is drained, and ultrapure water is injected to thoroughly clean the inlet and outlet connecting hoses and the inner wall of the annular reaction layer. After cleaning, the water in the connecting hose and the annular reaction layer is drained and the peristaltic pump is stopped.

Claims

1. A method for degrading antibiotics in water based on vacuum ultraviolet light, characterized in that: include: Add the sample water containing antibiotics into the sample container of the photoreaction device, turn on the magnetic stirrer, and make the liquid in the sample container evenly mixed under the action of the rapid rotation of the magnetic stirring rotor; Add Fenton reagent into the sample container so that the sample water reaches the preset reaction conditions; The peristaltic pump is turned on, and the reaction liquid in the sample container is pumped into the annular reaction layer under the action of the peristaltic pump, and reacts under the irradiation of a detachable vacuum ultraviolet light source to degrade the antibiotics in the sample water; The photoreaction device comprises: a photoreactor, a liquid circulation system and a constant temperature water bath layer; the photoreactor comprises: a detachable vacuum ultraviolet light source, a high-purity quartz annular reaction layer, a top cover body and a bottom cover body; the top and bottom of the photoreactor are respectively provided with a top cover body and a bottom cover body, and a detachable vacuum ultraviolet light source is vertically arranged in the photoreactor; the detachable vacuum ultraviolet light source is detachably fixed to the top cover body; a constant temperature water bath layer is sleeved on the outer side of the photoreactor; the liquid circulation system comprises: a magnetic stirrer, a liquid outlet pipe, a liquid return pipe and a sample container, one end of the liquid outlet pipe is connected to the sample container, the other end of the liquid outlet pipe is detachably connected to the high-purity quartz annular reaction layer, one end of the liquid return pipe is connected to the sample container, and the other end of the liquid return pipe is detachably connected to the high-purity quartz annular reaction layer; the magnetic stirrer is used to place the sample container, a magnetic stirring rotor is placed in the sample container, and a peristaltic pump is connected to the middle part of the liquid outlet pipe.

2. The method according to claim 1, characterized in that Fenton's reagent is FeCl3·6H2O and H2O2.

3. The method according to claim 1, characterized in that The method further comprises: The initial pH was adjusted using 0.1 M NaOH and HCl, and the initial pH value of the sample water was 4.

0.

4. The method according to claim 3, characterized in that The method further comprises: After adjusting the initial pH, add the following compounds: Sodium salts, as donors of inorganic anions IAs, include: NaNO3, NaHCO3 and NaCl; Humic acid HA, as a donor of natural organic matter; tert-Butanol, as hydroxyl radical HO ● quencher; p-Benzoquinone, as the hydroperoxide radical HO2 ● quencher; 5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) and 5-tert-butyl-5-methyl-1-pyrroline-N-oxide (BMPO) act as spin traps for free radicals.

5. The method according to claim 1, characterized in that The method further comprises: Reaction samples were collected at set time intervals, and excess NaHSO3 was quickly added to the reaction sample solution to eliminate the residual oxidant.

6. The method according to claim 1, characterized in that The method further comprises: Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS / MS) was used to determine the concentration of sulfadimethoxine (SMN); The mobile phase was a mixture of 0.2% formic acid solution (65%) and acetonitrile (35%); the flow rate was 0.3 mL / min, the column temperature was 30°C, and the injection volume was 5 μL; the mass spectrometry adopted positive ion electrospray ionization mode, and the detection m / z were 279.3, 92.0 and 186.0, respectively; the SMN retention time was 1.32 min, and the quantification limit was 1.80 nM.

7. The method according to claim 1, characterized in that The method further comprises: The Fe 2+ The detection wavelength was 510 nm.

8. The method according to claim 1, characterized in that The method further comprises: Electron paramagnetic resonance spectroscopy was used to measure the free radical concentration; free radicals included: HO ● HO2 ● , DMPO spin traps and BMPO spin traps; In the determination process, DMPO and BMPO were used as spin trapping agents; the test temperature was 25°C, the microwave frequency was 9.8 GHz, and the modulation frequency was 100 kHz; The central magnetic field of the DMPO system is 3509.76G, and that of the BMPO system is 3503.39G.

9. The method according to claim 6, characterized in that The method further comprises: According to the measured SMN concentration, the degradation kinetic curve was analyzed and obtained.

10. The method according to claim 1, characterized in that Before adding the sample water containing the antibiotics into the sample container of the photoreaction device, the method further comprises: Installing a detachable vacuum ultraviolet light source to the photoreaction device; the detachable light source is a detachable vacuum ultraviolet light source; Turn on the cooling circulator, pump ultrapure water into the constant temperature water bath through the cooling water inlet and discharge it back through the cooling water outlet; Turning on the detachable vacuum ultraviolet light source of the photoreaction device to preheat the irradiation chamber; Open the high-purity nitrogen gas storage cylinder, and continuously introduce high-purity nitrogen into the irradiation chamber through the high-purity nitrogen gas inlet and discharge it from the high-purity nitrogen gas exhaust port, so that the irradiation chamber is filled with high-purity nitrogen.

11. The method according to claim 10, characterized in that The water temperature of the thermostatic water bath was kept constant at 25°C.

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