Method for preparing sulfur vacancy-containing thioureite and degrading antibiotics in wastewater

Abstract

The invention discloses a method for preparing sulfur vacancy-containing thioureite and degrading antibiotics in wastewater. According to the method, water is activated by sulfur vacancy-containing thioureite to generate hydroxyl free radicals (OH) and hydrogen free radicals (H) so as to synergistically degrade halogen-containing antibiotics. In the process, the sulfur vacancy-containing thioureite is used as a repairing material, and water is used as a precursor of free radicals. The existence of the sulfur vacancies promotes the water molecules to generate uniform cracking, and hydroxyl free radicals and hydrogen free radicals with high reactivity are generated. The method effectively solves the problem that high-toxicity halogen-containing intermediates are easy to generate when the traditional wastewater treatment technology is used for treating halogen-containing antibiotic pollution, so that the method has very high popularization value.

Description

Technical Field

[0001] The invention relates to a method for treating antibiotic-contaminated wastewater, in particular to a method for degrading antibiotics in wastewater using sulfur-vacancy pyrite, and belongs to the field of environmental pollution control. Background Art

[0002] Antibiotics are effective drugs that kill the physiological activity of pathogenic microorganisms and are widely used in the pharmaceutical, livestock and poultry, and aquatic industries. However, antibiotics are difficult to be completely absorbed and transformed by organisms, and a large amount of residual antibiotics and their active antibacterial components will be released into the environment in the form of metabolic waste, destroying the ecological balance. Among them, halogenated antibiotics are the most serious. Halogenated antibiotics refer to antibiotics that contain halogen atoms in their molecular structure. These drugs are widely used because of their strong biological activity and strong drug resistance. However, they are not only difficult to be degraded in the environment, but their diluted residues can persist in water bodies, affecting the ecosystem.

[0003] At present, the commonly used methods for treating halogenated antibiotic wastewater include biodegradation and chemical oxidation. Biodegradation is the use of microorganisms and their metabolic processes to decompose and transform halogenated antibiotics, but some microorganisms have limited ability to degrade halogenated antibiotics and may cause drug resistance. Chemical oxidation produces strong oxidative reactive oxygen species (ROS) such as •OH, •OOH and 1 O2 is used to degrade halogenated antibiotics. However, during the reaction, highly toxic, complex, and stable halogenated intermediates are easily produced, making them difficult to be effectively removed in traditional water treatment processes. Therefore, it is urgent to develop an efficient and low-toxic method for treating halogenated antibiotic wastewater. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for degrading antibiotics in wastewater by sulfur-vacancy pyrite.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: According to a first aspect of an embodiment of the present invention, a method for preparing a sulfur-containing vacancy pyrite is provided, comprising the following steps: Step S1. Synthesis of pyrite 6 mmol of thiourea was added to 60.0 mL of ethylene glycol, and after the thiourea was completely dissolved by stirring, ferric chloride hexahydrate (FeCl3•6H2O) was immediately added, and stirring was continued until all substances in the solution were fully dissolved and mixed evenly; the mixture was transferred to a high-pressure reactor and reacted at 180 °C for 12 h; after the reaction was completed, it was naturally cooled to room temperature, the solid was collected, washed and dried to obtain a block-like black solid substance; the block-like black substance was crushed to a black powder, and pyrite was obtained; Step S2. Constructing sulfur vacancies on the surface of pyrite The pyrite powder obtained in step S1 is placed in a tube furnace, the temperature of the tube furnace is increased from room temperature to 300°C at a heating rate of 10°C / min, and vacuum heat treatment is maintained at 300°C for 4 h, then naturally cooled to room temperature, and the black powder obtained is taken out, which is pyrite rich in surface sulfur vacancies.

[0006] Furthermore, in step S1, the particle size of the crushed pyrite particles ranges from 1 μm to 50 μm.

[0007] Furthermore, in step S2, the particle size of the sulfur-vacancy pyrite powder is in the range of 1 μm to 50 μm.

[0008] Furthermore, in step S1, 3 mmol of ferric chloride hexahydrate is added.

[0009] According to a second aspect of an embodiment of the present invention, a method for degrading antibiotics in wastewater with sulfur-vacancy pyrite is provided, comprising the following steps: adding sulfur-vacancy pyrite to wastewater containing antibiotics, and shaking the reaction on a shaker for more than 60 minutes.

[0010] Furthermore, the antibiotic in the wastewater is any one of thiamphenicol, chloramphenicol, and ciprofloxacin, and the concentration does not exceed 50 mg / L.

[0011] Furthermore, the pH value of the wastewater is 3-14.

[0012] Furthermore, the added sulfur-containing vacancy pyrite is 0.5 to 2 g / L.

[0013] Theoretical analysis: The present invention uses sulfur-vacancy pyrite as a key material to promote the splitting of water molecules into highly reactive free radicals •OH and •H groups. First, the •H group is used to undergo a hydrogenation reaction to achieve targeted dehalogenation of halogen-containing antibiotics, and then the organic matter is deeply oxidized through the hydroxylation oxidation reaction of the free radical •OH, thereby achieving low-toxic transformation and deep oxidation of the halogen-containing antibiotics.

[0014] In the above reaction process, the stable water activation and uniform cleavage process are attributed to the inverse spinel structure of pyrite, whose high-spin iron atoms are arranged in antiparallel, so that the electrons can be effectively positioned on the sulfur vacancies and the adjacent hydrogen-bonding medium sulfur atoms. The electron-rich sulfur vacancies are conducive to the adsorption and subsequent activation of water molecules, while the sulfur atoms can extract hydrogen atoms from the activated H2O, thereby making the HO bond cleaved in an unimpeded manner on the pyrite surface to generate stable free radicals •OH and •H groups.

[0015] The present invention utilizes highly reactive free radicals generated by activated water of sulfur-containing vacancy pyrite and adopts an effective reduction-oxidation pathway to degrade halogen-containing antibiotics, thereby successfully solving the problem that traditional wastewater treatment methods are prone to produce highly toxic halogen-containing intermediates when treating halogen-containing antibiotic pollution.

[0016] Compared with the prior art, the advantages of the present invention are: (1) Sulfur vacancy pyrite is used to effectively activate water molecules to produce highly reactive •OH and •H. Through redox coupling, the formation of highly toxic halogen-containing intermediates is effectively avoided, and the low-toxic transformation and deep oxidation of halogen-containing antibiotics are achieved.

[0017] (2) Throughout the entire process, the degradation conditions for halogenated antibiotics are mild, the overall energy consumption is low, it has good environmental compatibility, and it complies with the principles of green chemistry.

[0018] (3) The key material used is sulfur-containing pyrite, which has a simple synthesis method, a wide range of raw material sources, an economical price, is environmentally friendly, and will not cause secondary pollution.

[0019] (4) The present invention is applicable to various industrial, agricultural, and medical sewage treatment fields, has industrial application prospects, and has good application prospects in the field of environmental governance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The X-ray diffraction (XRD) patterns of sulfide iron ore (Fe3S4) and sulfur vacancy sulfide iron ore (SV-Fe3S4); Figure 2 These are the electron paramagnetic resonance (EPR) spectra of sulfide iron ore (Fe3S4) and sulfur vacancy sulfide iron ore (SV-Fe3S4). DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only used to illustrate the technical solution of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are still within the protection scope of the present invention.

[0022] Example 1: Preparation of sulfur-containing vacancy pyrite Step S1. Synthesis of pyrite In the embodiments of the present invention, pyrite may be written as Fe3S4, and sulfur-vacancy pyrite may be written as SV-Fe3S4.

[0023] 6 mmol of thiourea (CH4N2S) was added to 60.0 mL of ethylene glycol (C2H6O2) and stirred for 30 min using a magnetic stirrer to completely dissolve the thiourea. Subsequently, 3 mmol of ferric chloride hexahydrate (FeCl3•6H2O) was immediately added and stirred for 30 min until all substances in the solution were fully dissolved and mixed evenly.

[0024] The mixture was transferred to a 100 mL stainless steel autoclave, placed in an electric constant temperature blast drying oven, and reacted at 180°C for 12 h. After the reaction was completed, it was naturally cooled to room temperature, the solid was collected, and centrifuged and washed twice with anhydrous methanol, carbon disulfide, and anhydrous methanol in sequence. Finally, the obtained product was placed in a vacuum drying oven at 30°C and dried for 24 hours to obtain a blocky black solid substance.

[0025] The obtained black block substance can be crushed into black powder using a mortar or ball mill to obtain pyrite.

[0026] The pyrite is crushed to a particle size ranging from 1 μm to 50 μm, which is convenient for the subsequent preparation of pyrite powder containing sulfur vacancies.

[0027] Step S2. Constructing sulfur vacancies on the surface of pyrite The pyrite powder obtained in S1 was placed in a tube furnace, and the temperature of the tube furnace was increased from room temperature to 300 °C at a heating rate of 10 °C / min. It was maintained at 300 °C for vacuum heat treatment for 4 h, and then naturally cooled to room temperature. The black powder obtained was pyrite rich in surface sulfur vacancies.

[0028] The particle size of the sulfur vacancy pyrite powder prepared by the method is 1 μm to 50 μm.

[0029] like Figure 1 As shown in the figure, the phase structure of the sulfide iron ore rich in surface sulfur vacancies was analyzed by X-ray diffraction spectroscopy (XRD). The results showed that the XRD pattern of the sulfide iron ore (Fe3S4) synthesized in step S1 was highly consistent with the Fe3S4 standard card (JCPDS No. 16-0713), and no other impurities were detected, indicating that the synthesized sample was high-purity Fe3S4. In addition, the XRD pattern of the sulfide iron ore (SV-Fe3S4) containing sulfur vacancies was also consistent with the standard card, indicating that the sulfur vacancies generated during the vacuum heat treatment process would not significantly affect the crystal structure of Fe3S4, and its inverse spinel structure was successfully retained.

[0030] like Figure 2 As shown in Figure 2, the sulfur vacancy concentration of pyrite rich in surface sulfur vacancies was analyzed using electron paramagnetic resonance spectroscopy (EPR). The EPR signal is simply defined as the degree of localization of unpaired electrons in solid-state materials.e3 Unlike S4, the stronger signal associated with the localized electrons of sulfur vacancies in SV-Fe3S4 indicates a significant increase in its electronic flexibility. Figure 2 As shown, after vacuum heat treatment, the EPR characteristic peak signal of sulfur vacancies on the Fe3S4 surface is significantly enhanced, indicating that sulfur vacancies are successfully constructed on the original Fe3S4 surface.

[0031] Example 2: Degradation of norfloxacin by pyrite and pyrite containing sulfur vacancies The raw material solution of simulated wastewater was prepared: the concentration of norfloxacin was 5 mg / L, and the initial pH value of the wastewater was adjusted to 3.4.

[0032] The pyrite and sulfur-containing vacancy pyrite (particle size range of 1 μm to 20 μm) prepared in Example 1 were added to 100 mL of norfloxacin wastewater at a ratio of 0.8 g / L. The wastewater was placed on a shaker, and after adding sulfur-containing vacancy pyrite powder, the shaker was started at a speed of 100 rpm, and the reaction occurred. The reaction was started, and samples were taken at 0, 10, 30, 60, 90, and 150 minutes, and the norfloxacin concentration was tested by high performance liquid chromatography. The removal results are shown in Table 1 below: Table 1 Changes of norfloxacin concentration over time during degradation process Example 3: Degradation of ciprofloxacin by pyrite and pyrite containing sulfur vacancies The raw material solution of simulated wastewater was prepared: the concentration of ciprofloxacin was 5 mg / L, and the initial pH value of the wastewater was adjusted to 7.2.

[0033] The pyrite and sulfur-containing vacancy pyrite (particle size of 20-40 μm) prepared in Example 1 were added to 100 mL of ciprofloxacin wastewater at a ratio of 1.2 g / L. The wastewater was placed on a shaker, and after adding sulfur-containing vacancy pyrite powder, the shaker was started, and the shaker speed was 250 rpm for the reaction to occur. The reaction was started, and samples were taken at 0, 10, 30, 60, 90, and 150 minutes, and the ciprofloxacin concentration was tested by high performance liquid chromatography. The removal results are shown in Table 2 below: Table 2 Changes of concentration of ciprofloxacin during degradation over time Example 4: Degradation of chloramphenicol by pyrite and pyrite containing sulfur vacancies The raw material solution of simulated wastewater was prepared: the concentration of chloramphenicol was 50 mg / L, and the initial pH value of the wastewater was adjusted to 10.5.

[0034] Add pyrite or sulfur-vacancy pyrite (particle size of 0.5-10 μm) to 100 mL of chloramphenicol wastewater at a ratio of 1 g / L. Place the wastewater on a shaker, add sulfur-vacancy pyrite powder, start the shaker, and the shaker speed is 200 rpm for the reaction to occur. Start the reaction, take samples at 0, 10, 30, 60, 90, and 150 minutes, and test the chloramphenicol concentration using high performance liquid chromatography. The removal results are shown in Table 3 below: Table 3 Changes of concentration over time during chloramphenicol degradation process Example 5: Degradation of thiamphenicol by pyrite and pyrite containing sulfur vacancies The raw material solution of simulated wastewater was prepared: the concentration of thiamphenicol was 50 mg / L, and the initial pH value of the wastewater was adjusted to 13.

[0035] Add sulfide iron ore or sulfur-vacancy sulfide iron ore (particle size of 5-50μm) to 100 mL of thiamphenicol wastewater at a ratio of 1 g / L. Place the wastewater on a shaker, add sulfur-vacancy sulfide iron ore powder, start the shaker, and the reaction occurs. Start the reaction, take samples at 0, 10, 30, 60, 90, and 150 minutes, and test the thiamphenicol concentration using high performance liquid chromatography. The removal results are shown in Table 4 below: Table 4 Changes of concentration of thiamphenicol during degradation process over time Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing sulfur-containing vacancy pyrite, characterized in that The following steps are involved: Step S1. Synthesis of pyrite 6mmol of thiourea was added to 60.0mL of ethylene glycol, and after the thiourea was completely dissolved by stirring, ferric chloride hexahydrate (FeCl3•6H2O) was immediately added, and stirring was continued until all substances in the solution were fully dissolved and mixed evenly; the mixture was transferred to a high-pressure reactor and reacted at 180°C for 12h; after the reaction was completed, it was naturally cooled to room temperature, the solid was collected, and it was washed and dried to obtain a block-like black solid substance; the block-like black substance was crushed to a black powder, and pyrite was obtained; Step S2. Constructing sulfur vacancies on the surface of pyrite The pyrite powder obtained in step S1 is placed in a tubular furnace, the temperature of the tubular furnace is increased from room temperature to 300°C at a heating rate of 10°C / min, and vacuum heat treatment is maintained at 300°C for 4 hours, then naturally cooled to room temperature, and the black powder obtained is the pyrite rich in surface sulfur vacancies.

2. The method for preparing the sulfur-containing vacancy pyrite according to claim 1, characterized in that: In the step S1, the particle size of the crushed pyrite particles ranges from 1 μm to 50 μm.

3. The method for preparing the sulfur-containing vacancy pyrite according to claim 1, characterized in that: In the step S2, the particle size of the sulfur vacancy pyrite powder is in the range of 1 μm to 50 μm.

4. The method for preparing the sulfur-containing vacancy pyrite according to claim 1, characterized in that: In the step S1, 3 mmol of ferric chloride hexahydrate is added.

5. A method for degrading antibiotics in wastewater using sulfur-vacancy pyrite, characterized in that The following steps are involved: Add sulfur-vacancy pyrite to the wastewater containing antibiotics, and shake on a shaker to allow the reaction to proceed for more than 60 minutes.

6. The method for degrading antibiotics in wastewater by sulfur-vacancy pyrite according to claim 5, characterized in that: The antibiotic in the wastewater is any one of thiamphenicol, chloramphenicol and ciprofloxacin, and the concentration does not exceed 50 mg / L.

7. The method for degrading antibiotics in wastewater from sulfur-vacancy pyrite according to claim 5, characterized in that: The pH value of the wastewater is 3-14.

8. The method for degrading antibiotics in wastewater by sulfur-vacancy pyrite according to claim 5, characterized in that: The amount of sulfur-containing vacancy pyrite added is 0.5-2 g / L.

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