A method for preparing and degrading antibiotics in wastewater with sulfur-vacancy-containing greigite

Abstract

The present invention discloses a method for preparing sulfur-deficient greigite and degrading antibiotics in wastewater. This method utilizes sulfur-deficient greigite to activate water to generate hydroxyl radicals (•OH) and hydrogen radicals (•H) for synergistically degrading halogen-containing antibiotics. In this process, sulfur-deficient greigite serves as a remediation material, and water serves as a precursor for free radicals. The presence of sulfur vacancies promotes the homolytic cleavage of water molecules to generate highly reactive hydroxyl radicals and hydrogen radicals. This method effectively solves the problem that traditional wastewater treatment technologies are prone to generating highly toxic halogen-containing intermediates when treating halogen-containing antibiotic pollution, and thus has high popularization value.

Description

Technical Field

[0001] The present invention relates to a method for treating antibiotic - contaminated wastewater, and particularly to a method for degrading antibiotics in wastewater by sulfur - deficient greigite, belonging to the field of environmental pollution control. Background Art

[0002] Antibiotics are effective drugs for killing the physiological activities of pathogenic microorganisms and are widely used in industries such as medicine, livestock and poultry, and aquaculture. 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 wastes, disrupting the ecological balance. Among them, halogen - containing antibiotics are the most serious. Halogen - containing antibiotics refer to antibiotics whose molecular structures contain halogen atoms. These drugs are widely used due to their strong biological activity and strong drug resistance. However, they are not only difficult to degrade in the environment, but also their diluted residues can persist in water bodies, affecting the ecosystem.

[0003] Currently, when treating halogen - containing antibiotic wastewater, common methods include biodegradation and chemical oxidation. Biodegradation uses microorganisms and their metabolic processes to decompose and transform halogen - containing antibiotics. However, the degradation ability of some microorganisms for halogen - containing antibiotics is limited, and it may lead to the problem of drug resistance. The chemical oxidation method degrades halogen - containing antibiotics by generating strongly oxidizing reactive oxygen species (ROS) such as •OH, •OOH and 1 O2. However, during the reaction process, highly toxic, structurally complex, and stable halogen - containing intermediates are easily generated, making it difficult to effectively remove them in traditional water treatment processes. Therefore, there is an urgent need to develop a highly efficient and low - toxic method for treating halogen - containing 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 - deficient greigite.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] According to the first aspect of the embodiments of the present invention, a preparation method of sulfur - deficient greigite is provided, including the following steps:

[0007] Step S1. Synthesis of greigite

[0008] 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;

[0009] Step S2. Constructing sulfur vacancies on the surface of pyrite

[0010] 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.

[0011] Furthermore, in step S1, the particle size of the crushed pyrite particles ranges from 1 μm to 50 μm.

[0012] Furthermore, in step S2, the particle size of the sulfur-vacancy pyrite powder is in the range of 1 μm to 50 μm.

[0013] Furthermore, in step S1, 3 mmol of ferric chloride hexahydrate is added.

[0014] 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.

[0015] Furthermore, the antibiotic in the wastewater is any one of thiamphenicol, chloramphenicol, and ciprofloxacin, and the concentration does not exceed 50 mg / L.

[0016] Furthermore, the pH value of the wastewater is 3-14.

[0017] Furthermore, the added sulfur-containing vacancy pyrite is 0.5 to 2 g / L.

[0018] Theoretical analysis:

[0019] 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.

[0020] During the above reaction process, both the stable water activation and the homogeneous cleavage processes are attributed to the inverse spinel structure of pyrite, in which the high-spin iron atoms are arranged in an anti-parallel manner, enabling electrons to be effectively localized on the sulfur vacancies and the adjacent hydrogen-bonded 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 enabling the H-O bond to cleave on the surface of pyrite in an unobstructed manner, generating stable radical •OH and •H groups.

[0021] The present invention utilizes the highly reactive radicals generated by activating water with sulfur-vacancy-containing pyrite to degrade halogenated antibiotics through an effective reduction-oxidation pathway, successfully solving the problem that traditional wastewater treatment methods are prone to generate highly toxic halogenated intermediates when treating halogenated antibiotic pollution.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] (1) Utilize sulfur-vacancy-containing pyrite to effectively activate water molecules, generating highly reactive •OH and •H. Through the way of redox coupling, the generation of highly toxic halogenated intermediates is effectively avoided, realizing the low-toxic transformation and deep oxidation of halogenated antibiotics.

[0024] (2) Throughout the whole process, the degradation reaction conditions of halogenated antibiotics are mild, the overall energy consumption is low, it has good environmental compatibility, and conforms to the principles of green chemistry.

[0025] (3) The key material used, sulfur-containing pyrite, has a simple synthesis method, wide raw material sources, economical price, environmental friendliness, and will not cause secondary pollution.

[0026] (4) The present invention is applicable to the sewage treatment fields of various industries, agriculture, and medicine, has industrial application prospects, and has good application prospects in the field of environmental governance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the X-ray diffraction (XRD) pattern of pyrite (Fe3S4) and sulfur-vacancy-containing pyrite (SV-Fe3S4);

[0028] Figure 2 is the electron paramagnetic resonance (EPR) spectrum of pyrite (Fe3S4) and sulfur-vacancy-containing pyrite (SV-Fe3S4). DETAILED DESCRIPTION OF THE INVENTION

[0029] 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.

[0030] Example 1: Preparation of sulfur-containing vacancy pyrite

[0031] Step S1. Synthesis of pyrite

[0032] In the embodiments of the present invention, pyrite may be written as Fe3S4, and sulfur-vacancy pyrite may be written as SV-Fe3S4.

[0033] 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.

[0034] 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.

[0035] The obtained black block substance can be crushed into black powder using a mortar or ball mill to obtain pyrite.

[0036] 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.

[0037] Step S2. Constructing sulfur vacancies on the surface of pyrite

[0038] 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.

[0039] The particle size of the sulfur vacancy pyrite powder prepared by the method is 1 μm to 50 μm.

[0040] like Figure 1As shown in the figure, the X-ray diffraction spectrum (XRD) was used to analyze the phase structure of greigite rich in surface sulfur vacancies. The results showed that the XRD pattern of the greigite (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 sulfur-vacancy-containing greigite (SV-Fe3S4) was also consistent with the standard card, indicating that the sulfur vacancies generated during the vacuum heat treatment did not significantly affect the crystal structure of Fe3S4, and its inverse spinel structure was successfully retained.

[0041] As Figure 2 shown, an electron paramagnetic resonance spectrometer (EPR) was used to analyze the sulfur vacancy concentration of greigite rich in surface sulfur vacancies. The EPR signal is simply defined as the degree of localization of unpaired electrons in solid materials. Different from F e3 S4, the stronger signal related to the localized electrons of sulfur vacancies in SV-Fe3S4 shows a significant increase in its electron flexibility. As Figure 2 shown, after vacuum heat treatment, the EPR characteristic peak signal of sulfur vacancies on the surface of Fe3S4 was significantly enhanced, indicating that sulfur vacancies were successfully constructed on the surface of the original Fe3S4.

[0042] Example 2: Degradation of norfloxacin by greigite and sulfur-vacancy-containing greigite

[0043] Prepare the raw material liquid for simulating wastewater: the concentration of norfloxacin is 5 mg / L, and the initial pH value of the wastewater is adjusted to 3.4.

[0044] The greigite and sulfur-vacancy-containing greigite (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. After adding the sulfur-vacancy-containing greigite 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 measured using high-performance liquid chromatography. The removal results are shown in Table 1 below:

[0045] Table 1 Changes in the concentration of norfloxacin during the degradation process

[0046]

[0047] Example 3: Degradation of ciprofloxacin by greigite and sulfur-vacancy-containing greigite

[0048] Prepare the raw material liquid for simulating wastewater: the concentration of ciprofloxacin is 5 mg / L, and the initial pH value of the wastewater is adjusted to 7.2.

[0049] Add the pyrite and sulfur vacancy-containing pyrite prepared in Example 1 (particle size: 20 - 40 μm) to 100 mL of ciprofloxacin wastewater at a ratio of 1.2 g / L. Place the wastewater on a shaker. After adding the sulfur vacancy-containing pyrite powder, start the shaker with a rotation speed of 250 rpm to initiate the reaction. Start the reaction and take samples at 0, 10, 30, 60, 90, and 150 minutes, and use high-performance liquid chromatography to measure the ciprofloxacin concentration. The removal results are shown in Table 2 below:

[0050] Table 2 Changes in concentration of ciprofloxacin during the degradation process over time

[0051]

[0052] Example 4: Degradation of chloramphenicol by pyrite and sulfur vacancy-containing pyrite

[0053] Prepare the raw material solution for the simulated wastewater: the chloramphenicol concentration is 50 mg / L, and the initial pH value of the wastewater is adjusted to 10.5.

[0054] Add pyrite or sulfur vacancy-containing pyrite (particle size: 0.5 - 10 μm) to 100 mL of chloramphenicol wastewater at a ratio of 1 g / L. Place the wastewater on a shaker. After adding the sulfur vacancy-containing pyrite powder, start the shaker with a rotation speed of 200 rpm to initiate the reaction. Start the reaction and take samples at 0, 10, 30, 60, 90, and 150 minutes, and use high-performance liquid chromatography to measure the chloramphenicol concentration. The removal results are shown in Table 3 below:

[0055] Table 3 Changes in concentration of chloramphenicol during the degradation process over time

[0056]

[0057] Example 5: Degradation of thiamphenicol by pyrite and sulfur vacancy-containing pyrite

[0058] Prepare the raw material solution for the simulated wastewater: the thiamphenicol concentration is 50 mg / L, and the initial pH value of the wastewater is adjusted to 13.

[0059] Add pyrite or sulfur vacancy-containing pyrite (particle size: 5 - 50 μm) to 100 mL of thiamphenicol wastewater at a ratio of 1 g / L. Place the wastewater on a shaker. After adding the sulfur vacancy-containing pyrite powder, start the shaker to initiate the reaction. Start the reaction and take samples at 0, 10, 30, 60, 90, and 150 minutes, and use high-performance liquid chromatography to measure the thiamphenicol concentration. The removal results are shown in Table 4 below:

[0060] Table 4 Changes in concentration of thiamphenicol during the degradation process over time

[0061]

[0062] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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 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 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 performed at 300°C for 4 hours, and then the temperature is naturally cooled to room temperature, and the black powder obtained is taken out, which is pyrite rich in surface sulfur vacancies; In the step S1, the particle size of the crushed pyrite particles ranges from 1 μm to 50 μm; In the step S2, the particle size of the sulfur vacancy pyrite powder is in the range of 1 μm to 50 μm; In the step S1, 3 mmol of ferric chloride hexahydrate is added.

2. A method for degrading antibiotics in wastewater using sulfur-vacancy pyrite prepared by the method of claim 1, 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.

3. The method for degrading antibiotics in wastewater by sulfur-vacancy pyrite according to claim 2, 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.

4. The method for degrading antibiotics in wastewater by sulfur-vacancy pyrite according to claim 2, characterized in that: The pH value of the wastewater is 3-14.

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

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