Method for photodegrading sulfadiazine in water body

Abstract

The invention provides a method for photodegrading sulfadiazine in a water body, and belongs to the technical field of water treatment. The method for photodegrading sulfadiazine in the water body comprises the following steps: collecting a water sample in a plateau lake, and extracting to obtain a soluble organic matter extract; and mixing the soluble organic matter extract with a sulfadiazine-containing water body, and carrying out degradation treatment under an illumination condition. According to the method, the soluble organic matter extract is extracted from the plateau lake water sample, the sulfadiazine can be degraded under the illumination condition, the sulfadiazine in the sulfadiazine-containing water body is removed, the operation is simple, and the sulfadiazine removal rate is high.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, in particular to a method for photodegrading sulfadiazine in water. Background Art

[0002] Due to the extensive use of antibiotics, many types of antibiotics are frequently detected in lakes and offshore areas. Therefore, the pollution caused by antibiotics to the water environment has become one of the major environmental issues that people are increasingly concerned about. Among them, sulfonamide antibiotics such as sulfadiazine have good antibacterial and antibacterial abilities and are widely used in medical enterprises, animal husbandry and aquaculture, as well as agriculture. It is one of the most widely used and largest-volume antibiotics. Therefore, sulfadiazine has become one of the antibiotics frequently detected in the water environment. However, sulfadiazine is difficult to remove through the general sewage treatment process of sewage treatment plants. Summary of the invention

[0003] The object of the present invention is to provide a method for photodegrading sulfadiazine in water. The method provided by the present invention is used to treat water containing sulfadiazine, and the operation is simple and the sulfadiazine removal rate is high.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for photodegrading sulfadiazine in water, comprising the following steps: Water samples were collected from plateau lakes for extraction to obtain dissolved organic matter extracts; The soluble organic matter extract is mixed with the water body containing sulfadiazine and subjected to degradation treatment under light conditions.

[0005] Preferably, the plateau lakes include one or more of Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake and Xingyun Lake.

[0006] Preferably, the extraction comprises sequential filtration and reverse osmosis concentration.

[0007] Preferably, the filter membrane used for the filtration is a water filter membrane with a pore size of 0.45 μm.

[0008] Preferably, the reverse osmosis concentration is performed 3 to 4 times.

[0009] Preferably, the sulfadiazine-containing water body comprises pharmaceutical factory wastewater and / or domestic sewage.

[0010] Preferably, the concentration of sulfadiazine in the sulfadiazine-containing water is 0.005-0.05 mmol / L.

[0011] Preferably, after the soluble organic matter extract is mixed with the water containing sulfadiazine, the concentration of soluble organic matter in the obtained mixed liquid is 4~6 mg C / L; the pH value of the mixed liquid is 6.8~7.2.

[0012] Preferably, the lighting is natural lighting.

[0013] Preferably, the degradation treatment temperature is 20-25°C and the time is ≥1h.

[0014] Beneficial effects: The present invention extracts soluble organic matter extracts from plateau lake water samples, which can degrade sulfadiazine under light conditions to achieve the removal of sulfadiazine from sulfadiazine-containing water bodies, with simple operation and high sulfadiazine removal rate. The results of the embodiment show that after the sulfadiazine-containing water body is treated by the above method, the removal rate of sulfadiazine in the purified water body can reach 34.41~45.32%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the spectrum of a 500W high pressure mercury lamp; Figure 2 This is the relationship between the reaction concentration and time of the DOM extract from Yangzonghai; Figure 3 This is the relationship between the reaction concentration and time of Erhai Lake DOM extract; Figure 4 This is the relationship between the reaction concentration and time of the Fuxian Lake DOM extract; Figure 5 This is the relationship between the reaction concentration and time of the DOM extract of Dianchi Lake; Figure 6 This is the relationship between the reaction concentration and time of the Qilu Lake DOM extract; Figure 7 This is the relationship between the reaction concentration and time of the DOM extract from Xingyun Lake; Figure 8 is the relationship between SRHA (DOM) reaction concentration and time; Fig. 9 is the relationship between SRFA (DOM) reaction concentration and time; Fig.10 is the relationship between PPFA (DOM) reaction concentration and time; Fig.11 for f TMP and E 2 :E 3 Linear fitting result diagram of ; Fig.12 for f TMP and Sr linear fitting results. DETAILED DESCRIPTION

[0016] The present invention provides a method for photodegrading sulfadiazine in water, comprising the following steps: Water samples were collected from plateau lakes for extraction to obtain dissolved organic matter extracts; The soluble organic matter extract is mixed with the water body containing sulfadiazine and subjected to degradation treatment under light conditions.

[0017] The present invention collects water samples from plateau lakes for extraction to obtain dissolved organic matter (DOM) extracts. In the present invention, the plateau lakes preferably include one or more of Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake and Xingyun Lake, more preferably Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake or Xingyun Lake, and further preferably Xingyun Lake. The present invention does not specifically limit the method for collecting the water samples, and the surface water samples of plateau lakes can be collected by methods well known to those skilled in the art. In the present invention, the extraction preferably includes filtration and reverse osmosis concentration in sequence; the filter membrane used for filtration is preferably a water filter membrane with a pore size of 0.45 μm; the number of reverse osmosis concentration is preferably 3 to 4 times. In an embodiment of the present invention, the reverse osmosis concentration is specifically carried out in a reverse osmosis machine, and the model of the reverse osmosis machine is BONA-GM-19.

[0018] After obtaining the soluble organic matter extract, the present invention mixes the soluble organic matter extract with the water body containing sulfadiazine and performs degradation treatment under light conditions. In the present invention, the water body containing sulfadiazine preferably includes pharmaceutical factory wastewater and / or domestic sewage. In the present invention, the concentration of sulfadiazine in the water body containing sulfadiazine is preferably 0.005~0.05mmol / L, more preferably 0.007~0.03mmol / L, further preferably 0.009~0.02mmol / L, and further preferably 0.01mmol / L. In the present invention, after the soluble organic matter extract is mixed with the sulfadiazine-containing water, the concentration of soluble organic matter in the obtained mixed liquid is preferably 4-6 mg C / L, more preferably 4.5-5.5 mg C / L, and further preferably 5 mg C / L; the pH value of the mixed liquid is preferably 6.8-7.2, more preferably 6.9-7.1, and further preferably 7.0. When the pH value of the mixed liquid does not meet the above requirements, the present invention preferably uses H 3 PO 4Or NaOH adjusts the pH value of the mixed liquid to the above requirements. In the present invention, the illumination is preferably natural illumination; in an embodiment of the present invention, a 500W high-pressure mercury lamp is used as the light source, and a 290nm cutoff filter is selected to simulate natural illumination. In the present invention, the temperature of the degradation treatment is preferably 20~25°C, the time is preferably ≥1h, more preferably 1~20h, further preferably 5~15h, and further preferably 8~12h.

[0019] In the present invention, after the sulfadiazine-containing water body is treated by the above method, the removal rate of sulfadiazine in the purified water body can reach 34.0-45.3%.

[0020] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The sources of the experimental drugs used in the following examples are as follows: acetonitrile (HPLC grade), isopropanol (HPLC grade), sulfadiazine, 2,4,6-trimethylphenol (TMP), sorbic acid, ammonium acetate, glacial acetic acid, sodium dihydrogen phosphate (NaH 2 PO 4 ·2H 2 O) and disodium hydrogen phosphate (Na 2 HPO 4 12H 2 O) was from JK&Scientific; p-nitroanisole (PNA) and pyridine (pyr) were purchased from TCI; SRHA, SRFA and PPFA were from the International Humic Acid Society (IHSS); ultrapure water (18.25 MPa) was prepared using an ultrapure water machine.

[0022] The experimental instruments used in the following examples are as follows: UV / visible spectrophotometer from Agilent Technologies (Evolution201); high performance liquid chromatograph from Agilent Technologies (1260 HPLC); electronic balance from Mettler Toledo (AL204); ultrasonic cleaning machine from Ningbo Xinzhi Biotechnology Co., Ltd. (SB-5200D), water bath nitrogen blower from Shanghai Qiqian Electronic Technology Co., Ltd. (NDK-12W), ultrapure water machine from Nanjing Oukai Environmental Technology Co., Ltd. (EU-K1-10TY), photochemical reaction instrument from Henan Kaifeng Hongxing Instrument Factory (OCRS-PX32T), pH meter from Shanghai Precision Scientific Instrument Co., Ltd. (PHS-3C); electric blast drying oven from Hangzhou Qikun Technology Co., Ltd. (101-2AB); total organic carbon analyzer from Hangzhou Qikun Technology Co., Ltd. (CD-800S); the container for water samples during simulated light exposure is a quartz test tube with an inner diameter of 1.75 cm.

[0023] Example 1 1. Sample preparation The sampling points of the water samples used in this experiment are located in Kunming and Yuxi, Yunnan Province. Six lakes were selected as sampling points, namely Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake and Xingyun Lake, named #1, #2, #3, #4, #5 and #6 respectively. The surface water samples were taken with a polyethylene instrument. The sampling volume of the water samples from the six lakes was 60L. The water samples were filtered with a water filter membrane with a pore size of 0.45μm, and then the filtered water samples were added to a reverse osmosis machine (BONA-GM-19) for 4 times of reverse osmosis concentration, that is, DOM was extracted and separated from the lake water samples by reverse osmosis concentration. The concentrated solution obtained after reverse osmosis concentration was the DOM extract (respectively recorded as Yangzonghai DOM extract, Erhai DOM extract, Fuxian Lake DOM extract, Dianchi DOM extract, Qilu Lake DOM extract, Xingyun Lake DOM extract), and the DOM extract was placed in a polyethylene bottle, and then the polyethylene bottle was placed in a refrigerator for freezing and storage at a storage temperature of -20°C.

[0024] 2. Photolysis experiment and UV absorbance experiment The photolysis experiment uses a photochemical reaction instrument (OCRS-PX32T) and a 500W high-pressure mercury lamp as the light source. Since the wavelength of sunlight is greater than 290nm, a 290nm cutoff filter is selected to simulate natural light. The spectrum of the 500W high-pressure mercury lamp is shown in Figure 1 shown.

[0025] The concentration of the sulfadiazine stock solution used in this experiment is 5 mM, and its preparation method is as follows: 0.03129 g of sulfadiazine (relative molecular mass is 250.28) solid powder is weighed with an electronic balance, poured into a 25 mL volumetric flask, and made up to volume with ultrapure water. Since the solubility of sulfadiazine in ultrapure water is low, the solubilization effect of an ultrasonic cleaner is not ideal, and NaOH solution is used to dissolve it. The pH value of the final sulfadiazine stock solution is 7, and the sulfadiazine stock solution is clear.

[0026] The preparation method of the phosphate buffer solution used in this experiment is as follows: prepare a sodium dihydrogen phosphate solution with a concentration of 0.2 mol / L and a sodium dihydrogen phosphate solution with a concentration of 0.2 mol / L respectively, and then mix the sodium dihydrogen phosphate solution and the sodium dihydrogen phosphate solution in a volume ratio of 0.39:0.61 to prepare a phosphate buffer solution.

[0027] The method for performing the photolysis experiment in this embodiment is as follows: 9 50 mL volumetric flasks are named 1 to 9, respectively, Yangzonghai DOM extract is added to No. 1, Erhai DOM extract is added to No. 2, Fuxian Lake DOM extract is added to No. 3, Dianchi Lake DOM extract is added to No. 4, Qilu Lake DOM extract is added to No. 5, Xingyun Lake DOM extract is added to No. 6, SRHA (DOM) is added to No. 7, SRFA (DOM) is added to No. 8, and PPFA (DOM) is added to No. 9. 100 μL of sulfadiazine stock solution is added to each volumetric flask, and the volume is fixed with phosphate buffer solution, wherein the DOM concentration in each volumetric flask is 5 mg C / L, and 9 experimental water samples are prepared, and the solution of each volumetric flask is poured into a beaker, and H 3 PO 4 Or adjust the pH value to 7 with NaOH, divide the solution in each beaker into three equal parts and add them into quartz test tubes with an inner diameter of 1.75 cm, for a total of 27 quartz test tubes, put all the quartz test tubes into a photolysis box, ensure that the quartz test tubes are exposed to the same light conditions, turn on the turntable so that the quartz test tubes can be subjected to photolysis experiments under uniform light conditions, the photolysis experiment is carried out at room temperature (25±2°C), wherein the temperature in the photolysis box is 20~25°C, samples are taken for testing during the photolysis experiment, and the interval between two adjacent samplings is at least 1h.

[0028] In the free radical quenching experiment, a quenching agent is added before the phosphate buffer solution is fixed to volume. The quenching agent includes isopropanol, sorbic acid or nitrogen, which is used to quench hydroxyl radicals (·OH), singlet oxygen ( 1 O 2 ), excited triplet state ( 3 DOM * ); wherein the amount of isopropanol added is 1 mL; the amount of sorbic acid added is 1 mL; the flow rate of nitrogen gas is to ensure that the solution is not flushed out of the test tube by the gas, and the ventilation time is 15 minutes.

[0029] In the experiment of calculating the quantum yield of various DOMs using TMP as a probe, 9 50 mL volumetric flasks were named 1 to 9, No. 1 was added with Yangzonghai DOM extract, No. 2 was added with Erhai DOM extract, No. 3 was added with Fuxian Lake DOM extract, No. 4 was added with Dianchi Lake DOM extract, No. 5 was added with Qilu Lake DOM extract, No. 6 was added with Xingyun Lake DOM extract, No. 7 was added with SRHA (DOM), No. 8 was added with SRFA (DOM), and No. 9 was added with PPFA (DOM). 100 μL of TMP was added to each volumetric flask, and the volume was fixed with phosphate buffer solution to prepare 9 experimental water samples. The subsequent operations were the same as the sulfadiazine photolysis experiment.

[0030] In the photolysis experiment of measuring PNA / pyr, four 50 mL volumetric flasks were named 1 to 4, and PNA and pyr in corresponding proportions were added to the corresponding numbered volumetric flasks. The volume was fixed with pure water, and a small amount of solution was taken out from each sample for measuring the ultraviolet absorbance. The subsequent operations were the same as those in the sulfadiazine photolysis experiment. The molar ratio of PNA to pyr is shown in Table 1.

[0031] Table 1 Molar ratio of PNA to pyr and addition amount

[0032] The UV absorbance experiment used a UV / visible spectrophotometer to measure the UV absorbance of Yangzonghai DOM extract, Erhai DOM extract, Fuxian Lake DOM extract, Dianchi Lake DOM extract, Qilu Lake DOM extract, Xingyun Lake DOM extract, SRHA (DOM), SRFA (DOM), PPFA (DOM), and the UV absorbance of samples with PNA to pyr molar ratios of 1:20, 1:50, 1:70, and 1:100, respectively.

[0033] 3. Experimental analysis After the photolysis experiment was completed, samples were collected. 500 μL of each sample was sampled and the concentrations of sulfadiazine, TMP and PNA were detected using a high performance liquid chromatograph. The composition of the mobile phase and the detection wavelength are shown in Table 2.

[0034] Table 2 Composition of mobile phase and detection wavelength

[0035] 4. Results Analysis and Discussion 4.1 Removal rate of sulfadiazine by different DOM extracts Table 3 shows the removal rates of sulfadiazine by different DOM extracts, specifically, samples were taken under different illumination time conditions during the photolysis experiment, and the samples were detected by high performance liquid chromatography. As shown in Table 3, the present invention uses DOM extracts to perform photodegradation treatment on the sulfadiazine-containing solution, and the removal rate of sulfadiazine can reach 34.41-45.32%.

[0036] Table 3 Removal rate of sulfadiazine by different DOM extracts

[0037] 4.2 Photodegradation kinetics of sulfadiazine in plateau lakes and contribution of DOM to sulfadiazine photodegradation This experiment ignored the degradation of sulfadiazine in other ways. Before adding the quencher, the concentration of sulfadiazine in the experimental water samples after being irradiated by the mercury lamp would decrease. Based on this, the contribution of DOM in plateau lake water to the photodegradation of sulfadiazine was studied. The following is a specific analysis of the degradation of sulfadiazine in 9 experimental water samples: Figure 2 This is the relationship between the reaction concentration and time of Yangzonghai DOM extract. Figure 3 This is the relationship between the reaction concentration and time of Erhai Lake DOM extract. Figure 4 This is the relationship between the reaction concentration and time of Fuxian Lake DOM extract. Figure 5 This is the relationship between the reaction concentration and time of the DOM extract from Dianchi Lake. Figure 6 This is the relationship between the reaction concentration and time of the Qilu Lake DOM extract. Figure 7 This is the relationship between the reaction concentration and time of the DOM extract from Xingyun Lake. Figure 8 is the relationship between SRHA (DOM) reaction concentration and time, Fig. 9 is the relationship between SRFA (DOM) reaction concentration and time, Fig.10 This is the relationship between the concentration of PPFA (DOM) and time. The vertical axis C in the figure represents the concentration of the compound at the end of the reaction, C 0 Indicates the concentration of the compound at the beginning of the reaction. Figure 2~Figure 10 It can be seen that when no quencher is added, sulfadiazine will be photodegraded, but after adding the quencher sorbic acid, the degradation rate of sulfadiazine is reduced by an order of magnitude, which can be regarded as no degradation. It can be seen that the excited triplet state ( 3 DOM * ) is the main active species leading to the photodegradation of sulfadiazine.

[0038] 4.3 Quantum yield coefficient ( f TMP ) The degradation rate of TMP was calculated based on the peak area obtained by HPLC. The results are shown in Table 4.

[0039] Table 4 Degradation rate of TMP ( k TMP )

[0040] The degradation rate of PNA was calculated based on the peak area obtained by HPLC. The results are shown in Table 5.

[0041] Table 5 Degradation rate of PNA ( k PNA )

[0042] The degradation rate of TMP in DOM extract was obtained k TMP and the degradation rate of PNA k PNA After that, the DOM extracts were further calculated. f TMP The results are shown in Table 6.

[0043] Table 6 DOM extracts f TMP value

[0044] 4.4 DOM absorption parameters of plateau lakes and f TMP The fitting results of The absorption parameters of DOM in plateau lakes are mainly calculated by E 2 :E 3 , S r , the results are shown in Table 7.

[0045] Table 7 Absorption parameters of DOM in plateau lakes

[0046] The calculated plateau lake absorption parameter E 2 :E 3 , S r For and f TMP Perform a linear fit, where Fig.11 for f TMP and E 2 :E 3 The linear fitting result diagram of , the relevant data are shown in Table 8; Fig.12 for f TMP The linear fitting results of and Sr are shown in Table 9.

[0047] Table 8 f TMP and E 2 :E 3 The fitting results of

[0048] Table 9 f TMP The fitting results of Sr

[0049] Among them, when the solution has a higher E 2 :E 3 and S r When the solution contains a high amount of aromatic ketones, ketones and other oxidizing groups, these oxidizing groups are all conducive to the formation of triplet excited states of DOM, so E 2 :E 3 and S r To characterize the ability of DOM to generate excited triplet states. From the above linear fitting results, we can see that f TMP and E 2 :E 3 and S r Has a good linear relationship, and when E 2 :E 3 , S r The larger the f TMP The larger it is, the larger the corresponding quantum yield value will be.

[0050] From the above examples, it can be seen that the DOM in Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake and Xingyun Lake can photodegrade sulfadiazine, which indicates that the DOM extract extracted from plateau lakes has a certain ability to degrade sulfadiazine in surface water. In the free radical quenching experiment, free radical quenchers such as isopropanol, nitrogen and sorbic acid were used to quench hydroxyl radicals (·OH), singlet oxygen ( 1 O 2 ), excited triplet state ( 3 DOM * ), the excited triplet state contributes most to the photodegradation of sulfadiazine, while hydroxyl radicals and singlet oxygen contribute little to the photodegradation of sulfadiazine. In addition, the photodegradation of sulfadiazine from Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake, Xingyun Lake and three international standard humic substances SRHA, SRFA, and PPFA f TMP The value shows that the quantum yield of Xingyun Lake is the highest. f TMP and E 2 :E3 As for the linear fitting results of Sr, DOM in Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake and Xingyun Lake has a good ability to produce excited triplet states, among which Xingyun Lake has the strongest ability to produce excited triplet states. In summary, the method provided by the present invention has made certain contributions to the treatment of sulfadiazine in plateau lakes, and is also helpful for the restoration of the ecological environment of plateau lakes and for studying the environmental effects of typical organic micropollutants in plateau lakes.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for photodegrading sulfadiazine in water, The following steps are involved: Water samples were collected from plateau lakes for extraction to obtain dissolved organic matter extracts; The soluble organic matter extract is mixed with the water body containing sulfadiazine and subjected to degradation treatment under light conditions.

2. The method according to claim 1, It is characterized in that The plateau lakes include one or more of Yangzonghai Lake, Erhai Lake, Fuxian Lake, Dianchi Lake, Qilu Lake and Xingyun Lake.

3. The method according to claim 1, It is characterized in that The extraction includes sequential filtration and reverse osmosis concentration.

4. The method according to claim 3, It is characterized in that The filter membrane used in the filtration is a water filter membrane with a pore size of 0.45 μm.

5. The method according to claim 3, It is characterized in that The reverse osmosis concentration is performed 3 to 4 times.

6. The method according to claim 1, It is characterized in that The sulfadiazine-containing water body includes pharmaceutical factory wastewater and / or domestic sewage.

7. The method according to claim 6, It is characterized in that The concentration of sulfadiazine in the sulfadiazine-containing water body is 0.005-0.05 mmol / L.

8. The method according to any one of claims 1 to 7, It is characterized in that After the soluble organic matter extract is mixed with the water containing sulfadiazine, the concentration of the soluble organic matter in the obtained mixed liquid is 4-6 mg C / L; and the pH value of the mixed liquid is 6.8-7.

2.

9. The method according to claim 8, It is characterized in that The lighting is natural lighting.

10. The method according to claim 1 or 9, It is characterized in that The temperature of the degradation treatment is 20-25° C., and the time is ≥1 h.

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