A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials

Abstract

The application discloses a method for efficiently degrading fluoroquinolone antibiotics by using natural mineral materials, and first synthesizes a natural ferrous sulfide mineral; the synthesized ferrous sulfide mineral is added into a fluoroquinolone antibiotic solution, a suitable buffer salt is used to adjust the pH of the reaction, and the degradation reaction of the fluoroquinolone antibiotic is started under uniform stirring in air. The method for oxidatively degrading typical fluoroquinolone antibiotics by using the ferrous sulfide mineral material overcomes the problems of the traditional Fenton system, such as large consumption of raw materials, strong requirement for strong acid, and easy secondary pollution. The synthesized low-concentration ferrous sulfide natural mineral material is used to realize the rapid degradation of typical fluoroquinolone antibiotics, such as enrofloxacin, ciprofloxacin and flumequine, under neutral conditions; and degradation product analysis shows that the reaction path is mainly a step-by-step ring-opening process of a piperazine ring, and a defluorohydroxylation process is a secondary path.

Description

Technical Field

[0001] This invention belongs to the field of degradation of halogenated organic pollutants, and specifically relates to a method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials. Background Technology

[0002] Antibiotics are now widely used in all aspects of human production and life. They are mainly used to treat human diseases, and are also used in animal husbandry, aquaculture, agriculture and other fields because they can cure animal diseases (Van Doorslaer X., Dewulf J., Van Langenhove H., et al. Fluoroquinolone antibiotics: an emerging class of environmental micropollutants[J]. Sci Total Environ, 2014, 500-501: 250-269. Davies J. Where have all the antibiotics gone?[J]. Can J Infect Dis Med Microbiol, 2006, 17(5): 287-290.). Fluoroquinolones (FQs) are the third most common antibiotics in the world and are listed as “critically important” antibiotics by the World Health Organization. They play an important role in the treatment of human and animal diseases (Collignon P., Powers JH, Chiller TM, et al. World Health Organization ranking of antimicrobials according to their importance in human medicine: A critical step for developing risk management strategies for the use of antimicrobials in food production animals[J]. Clin Infect Dis, 2009, 49(1): 132-141).Excessive use of fungicides (FQs) cannot be absorbed by organisms and is excreted, entering the environment through industrial wastewater, medical wastewater, municipal wastewater, livestock wastewater, etc. Because soil and sediments have a strong adsorption capacity for them, the FQs that enter the environment will be further redistributed, ultimately leading to high concentrations of FQs residues detectable in freshwater and seawater, soil and sediment, organisms, and even food. (Van Doorslaer X, Dewulf J, et al., Fluoroquinolone antibiotics: An emerging class of environmental micropollutants, Science of The Total Environment 500-501(2014)250-269; Riaz L., Mahmood T., Khalid A., et al. Fluoroquinolones (FQs) in the environment: A review on their abundance, sorption and toxicity in soil[J]. Chemosphere, 2018, 191:704-720; Brown KD, Kulis) J.,Thomson B.,et al.Occurrence of antibiotics inhospital,residential,and dairy effluent,municipal wastewater,and the RioGrande in New Mexico[J].Sci Total Environ,2006,366(2-3):772-783; Senta I.,Terzic S.,Ahel M.Occurrence and fate of dissolved and particulateantimicrobials in municipal wastewater treatment[J].Water Res,2013,47(2):705-714.).The widespread distribution of these antibiotics in the environment has led to the formation of drug-resistant genes in various environmental media, a rapid increase in the proportion of drug-resistant strains, and even the emergence of "superbugs," which will become a major threat to human health (Adachi F., Yamamoto A., Takakura K., et al. Occurrence of fluoroquinolones and fluoroquinolone-resistance genes in the aquatic environment[J]. Sci TotalEnviron, 2013, 444: 508; Redgrave LS, Sutton SB, Webber MA, et al. Fluoroquinolone resistance: mechanisms, impact on bacteria, and role inevolutionary success[J]. Trends Microbiol, 2014, 22(8): 438-445; Livermore DM, Hope R., Reynolds R., et al. Declining cephalosporin and fluoroquinolone non-susceptibility among bloodstream Enterobacteriaceae from the UK: links toprescribing change? [J].J Antimicrob Chemother,2013,68(11):2667-2674.).Furthermore, their accumulation in the body can affect the growth and development of organisms, and even induce various human diseases (Adomas B., Antczak-Marecka J., Nalecz-Jawecki G., et al. Phytotoxicity of enrofloxacin soil pollutant to narrow-leaved lupin plant[J]. Pol J Environ Stud, 2013, 22(1): 71-76; Shen R., Yu Y., Lan R., et al. The cardiovascular toxicity induced by highdoses of gatifloxacin and ciprofloxacin in zebrafish[J]. Environ Pollut, 2019, 254(Pt B): 112861). Therefore, it is crucial to efficiently remove FQs from the environment, especially from water bodies that serve as emission sources.

[0003] Currently, the main technologies for treating iron-containing gases (FQs) fall into three categories: physical, biological, and chemical treatments. Among these, chemical removal methods are more effective than physical and biological methods, and these methods are generally referred to as advanced oxidation processes (AOPs). Fenton is a common and highly efficient iron-based advanced oxidation technology. Although the Fenton reaction has high oxidation efficiency and is easy to operate, it also has drawbacks such as requiring acidic conditions, producing a large amount of iron-containing sludge, which may cause secondary pollution, and high reagent consumption (Giri, AS and Golder, AK, Ciprofloxacin degradation from aqueous solution by Fenton oxidation: reactionkinetics and degradation mechanisms, RSC Advances 4(13)(2014)6738; Gupta, A. and Garg, A. Degradation of ciprofloxacin using Fenton's oxidation: Effect of operating parameters, identification of oxidized by-products and toxicity assessment, Chemosphere 193(2018)1181-1188).Therefore, people have made various modifications to the Fenton reaction, using other iron-containing or other metal substances to replace ferrous ions, resulting in a variety of Fenton reaction systems. However, hydrogen peroxide is still required as an oxidant to generate reactive oxygen species (ROS) to degrade pollutants, and the synthesis process is relatively complex and the materials are difficult to obtain (Feng M., Wang Z., Dionysiou DD, et al. Metal-mediated oxidation of fluoroquinolone antibiotics in water: A review on kinetics, transformation products, and toxicity assessment[J]. J Hazard Mater, 2018, 344: 1136-1154; Wang J., Zhuan R. Degradation of antibiotics by advanced oxidation processes: An overview[J]. Sci Total Environ, 2020, 701: 135023). Natural iron mineral materials are readily available and have a strong adsorption capacity for FQs. For example, iron minerals such as goethite also have the ability to directly oxidize these antibiotics, but the oxidation reaction rate is very slow (Zhang H., Huang CH Adsorption and oxidation of fluoroquinolone antibacterial agents and structurally related amines with goethite[J].Chemosphere,2007,66(8):1502-1512.). Summary of the Invention

[0004] Objective: Current Fenton and Fenton-like reactions suffer from drawbacks such as large reagent dosages, extreme reaction conditions, generation of large amounts of iron-containing sludge, and difficulties in material acquisition. While common natural iron minerals are easy to obtain, they exhibit slow oxidation rates for fluoroquinolone antibiotics. This invention provides an advanced oxidation method for the efficient degradation of fluoroquinolone antibiotics using natural mineral materials. FeS minerals are synthesized in an anaerobic environment using Na₂S and FeCl₂. These FeS minerals are then added to a solution containing fluoroquinolone antibiotics, and degradation is carried out under uniform stirring in air. The surface of the FeS minerals effectively adsorbs fluoroquinolone antibiotics from the solution through electrostatic and coordination interactions. Furthermore, the surface reacts with oxygen to produce reactive oxygen species (ROS), rapidly degrading the adsorbed fluoroquinolone antibiotics.

[0005] Technical Solution: To achieve the above objectives, this invention provides a method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0006] (a) Synthesizing natural ferrous sulfide minerals;

[0007] (b) The synthesized ferrous sulfide minerals were added to a fluoroquinolone antibiotic solution, the pH of the reaction was adjusted with a suitable buffer salt, and the mixture was stirred evenly under air conditions to carry out the degradation reaction of the fluoroquinolone antibiotics.

[0008] The specific steps for synthesizing natural ferrous sulfide minerals in step (a) are as follows:

[0009] (1) Na2S solution was added dropwise to FeCl2 solution under anaerobic conditions;

[0010] (2) The solution in step (1) is stirred and aged under anaerobic conditions;

[0011] (3) Centrifuge the aged solution in step (2), discard the supernatant, and obtain the precipitate;

[0012] (4) Add oxygen-free water to the precipitate under anaerobic conditions and then shake to redisperse it;

[0013] (5) Centrifuge the well dispersed solution, discard the supernatant, and obtain the precipitate;

[0014] (6) Repeat steps (4)-(5) to redisperse the cleaned precipitate with anoxic water and store it in anaerobic conditions for later use.

[0015] In step (2), the molar ratio of Na2S to FeCl2 is 1-1.5:1.

[0016] Preferably, the Na2S solution has a concentration of 1.1 mol / L and a volume of 72 mL; the FeCl2 solution has a concentration of 0.57 mol / L and a volume of 120 mL.

[0017] In step (2), the stirring rate is 100-200 rpm and the aging time at room temperature is 60-80 h.

[0018] Preferably, the stirring speed is 100 rpm and the stirring aging time is 3 days.

[0019] In step (6), steps (4)-(5) are repeated 5-8 times.

[0020] Further, 5 mL of the ferrous sulfide mineral dispersion obtained in step (6) was taken out using a centrifuge tube, freeze-dried, and weighed to obtain the concentration of ferrous sulfide mineral in the dispersion.

[0021] In steps (1)-(6), except for centrifugation, all operations are performed under anaerobic conditions.

[0022] In step (b), the fluoroquinolone antibiotics include fluoroquinolones containing a piperazine ring structure, such as flumethin, ciprofloxacin, or enrofloxacin.

[0023] In step (b), 3-morpholinopropanesulfonic acid buffer (MOPS) is used to control the pH of the reaction system within the range of 7.0±0.1, or acetate-sodium acetate buffer is used to control the pH to 5.0±0.1, or 2-cyclohexylaminoethanesulfonic acid (CHES) buffer is used to control the pH to 9.0±0.1, and the concentration of the above buffers is 5 μM.

[0024] In step (b), ferrous sulfide minerals are added to a fluoroquinolone antibiotic solution at a concentration of 0.1-100 μM; the amount of FeS minerals used is 0.02-5 g / L. Specifically, in step (b), increasing the concentration of ferrous sulfide minerals from 0.02 g / L to 5.0 g / L initially increases the degradation effect, which then decreases.

[0025] In step (b), the dissolved oxygen content of the solution under air or aerobic conditions can significantly affect the degradation of fluoroquinolone antibiotics; at the same time, it can generate superoxide anion free radicals and hydroxyl free radicals under air or aerobic conditions to degrade fluoroquinolone antibiotics.

[0026] Preferably, in step (b), the concentration of FQs is 10 μM; the amount of FeS mineral is 0.02-5 g / L, and the final preferred amount of FeS mineral is 0.05 g / L; the reaction pH is adjusted to 5, 7, or 9, and the final preferred reaction pH is 7; the reaction time is 4 hours.

[0027] Preferably, in step (b), oxygen-free water that has been heated to remove oxygen and then cooled is used to study the effect of oxygen on the reaction rate.

[0028] Preferably, in step (b), 10 μM of enrofloxacin, ciprofloxacin, 1-(2-fluorophenyl)piperazine and flumethylquine are added to study the differences and characteristics of the degradation of different types of FQs by the present invention.

[0029] In this invention, all water used is ultrapure water. The pH of the reaction system is controlled within the range of 7.0±0.1 using MOPS, the pH is controlled at 5.0±0.1 using acetate-sodium acetate buffer, and the pH is controlled at 9.0±0.1 using CHES buffer.

[0030] This invention synthesizes the natural mineral material Maginotite (FeS) under anaerobic conditions using Na₂S and FeCl₂, achieving efficient degradation of ferrous sulfate (FQs) under aerobic conditions. The Fe(II) sites on the FeS surface efficiently adsorb FQs from solution through coordination and electrostatic interactions, rapidly reducing the concentration of FQs in the solution. Simultaneously, unlike other adsorbents, the Fe(II) sites on the FeS surface oxidize upon contact with oxygen, generating ROS, which can simultaneously degrade the adsorbed FQs. Mechanistic analysis suggests that this method is widely applicable to FQs containing piperazine rings in their structure. This method overcomes the shortcomings of traditional Fenton reactions, preventing the release of iron ions and secondary pollution, while also ensuring efficient degradation of FQs. The FeS material exists in solid form in solution, facilitating sedimentation and solid-liquid separation. Furthermore, FeS, as a natural mineral material, is simple to synthesize, readily available, and has promising application prospects.

[0031] The principle of this invention is as follows: Under pH conditions, the synthesized FeS mineral surface carries a negative charge, while FQs exist in the form of amphoteric molecules and can be adsorbed onto the mineral surface through electrostatic interactions. Simultaneously, the FeS surface has a large number of Fe(II) sites, which readily form coordination bonds with the carboxyl groups in the FQs molecular structure, thus adsorbing FQs through coordination interactions. Under these two mechanisms, FQs in solution can be rapidly adsorbed onto the mineral surface within minutes. Simultaneously, the Fe(II) sites on the FeS surface, upon contact with oxygen, are oxidized to Fe(III), generating superoxide anion radicals. These superoxide anion radicals are further converted into hydrogen peroxide and surface hydroxyl radicals under the influence of surface Fe(II). These ROS can capture electrons from the N atom of the piperazine ring and the carbon-carbon double bond of the quinolone structure in FQs through radical attack and electrophilic attack, forming positive ion radicals. Further oxidation leads to ring-opening cleavage of the piperazine ring and quinolone structure, efficiently degrading FQs. Figure 1 As the mineral concentration increases, the number of reaction sites increases, and the degradation rate of ENR gradually accelerates. However, when the concentration further increases, the reoxygenation process slows down due to the greater decrease in dissolved oxygen content in the system, thus slowing down the degradation rate. Oxygen plays a crucial role in the degradation of FQs in this process. Simultaneously, the synthesized FeS material is easy to settle, thereby achieving solid-liquid separation and preventing secondary pollution.

[0032] This invention proposes a method for the oxidative degradation of typical fluoroquinolone antibiotics using ferrous sulfide mineral materials, overcoming the problems of high raw material consumption, strong pH requirements, and susceptibility to secondary pollution associated with traditional Fenton systems. This invention achieves rapid degradation of typical fluoroquinolone antibiotics such as enrofloxacin, ciprofloxacin, and flumethylquinolone under neutral conditions using synthesized natural ferrous sulfide mineral materials, and further investigated the effect of different pH values ​​on the reaction. Analysis of the degradation products revealed that the main reaction pathway is a stepwise ring-opening process of the piperazine ring, with defluorination and hydroxylation as a secondary pathway.

[0033] This invention is the first to discover the simultaneous degradation of organic pollutants, particularly FQs, by generating both superoxide anion radicals and hydroxyl radicals during the oxidation process of low-concentration ferrous sulfide minerals (FeS, e.g., 0.05 g / L), especially under neutral conditions. This invention found that at lower mineral concentrations, the production amount and rate of superoxide anion radicals in the system are high, while the production amount and rate of hydroxyl radicals are low, indicating that superoxide anion radicals may play an important role in the degradation process.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0035] (1) This invention synthesizes natural mineral material Makino mineral FeS under anaerobic conditions using Na2S and FeCl2 solution. Under aerobic conditions, it can efficiently adsorb FQs in solution and achieve rapid degradation of typical FQs through a Fenton-like reaction. It is widely applicable to the degradation of FQs containing piperazine ring structure and quinolone structure in various structures.

[0036] (2) The amount of FeS mineral used in this invention is very small. At a concentration of 0.05 g / L, it can achieve efficient degradation of FQs within 2 hours. The reaction is carried out under neutral conditions and the conditions are mild.

[0037] (3) In this invention, FeS is in solid form before and after the reaction, which is easy to settle and thus achieve solid-liquid separation. At the same time, during the reaction, the iron ions react on the solid surface, avoiding the iron ions from entering the water body and avoiding the generation of secondary pollution.

[0038] (4) In this invention, FeS is a natural mineral material that is widely distributed in anaerobic environments, easy to obtain, and easy to synthesize in industry. It is a simple, readily available, and efficient degradation material. Attached Figure Description

[0039] Figure 1 This is a reaction route diagram of the present invention;

[0040] Figure 2 The XRD diffraction patterns of the FeS synthesized in this invention and the oxidized minerals are shown.

[0041] Figure 3 The FeSζ potential at different pH values ​​was measured using a laser particle size analyzer in this invention.

[0042] Figure 4 This invention describes the degradation kinetics of ENR at different FeS mineral concentrations.

[0043] Figure 5 This is the particle size distribution of the system under different experimental conditions measured by a laser particle size analyzer in this invention;

[0044] Figure 6 This invention illustrates the variation of dissolved oxygen concentration in the solution under different mineral concentrations.

[0045] Figure 7 The XRD diffraction patterns of FeS minerals at different reaction times in this invention are shown below.

[0046] Figure 8 The images show SEM images of FeS minerals in this invention at reaction times of 0 min (a, b), 30 min (c, d), 60 min (e, f), 120 min (g, h), and 240 min (i, j).

[0047] Figure 9 The figures show the variations in total ferrous iron (a), solution-state ferrous iron (b), and total iron concentration (c) under different FeS mineral concentrations in this invention.

[0048] Figure 10 This refers to the changes in sulfite and sulfate concentrations during the ENR degradation process in this invention.

[0049] Figure 11 This invention demonstrates the degradation of ENR by FeS under different reaction atmospheres.

[0050] Figure 12 To illustrate the degradation of ENR by FeS at different pH levels in this invention, (a) changes in total concentration and (b) changes in solution concentration;

[0051] Figure 13 The XRD patterns of FeS over time are shown in (a) pH = 5.0 and (b) pH = 9.0 in this invention.

[0052] Figure 14 The degradation of different types of fluoroquinolone antibiotics by FeS in this invention is shown in (a) changes in total concentration and (b) changes in solution concentration.

[0053] Figure 15 This is a quenching experiment for ENR degradation in this invention;

[0054] Figure 16This is an experiment to capture hydroxyl radicals in this invention;

[0055] Figure 17 This is an experiment to capture superoxide anion free radicals in this invention;

[0056] Figure 18 The electron paramagnetic resonance spectrum of the FeS aqueous dispersion in this invention is shown, with DMPO as the scavenging agent.

[0057] Figure 19 The degradation pathways of ENR in the (a) FeS system and (b) Fenton system in this invention are shown. Detailed Implementation

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0059] Unless otherwise specified, the experimental methods described in these examples are conventional methods. Unless otherwise specified, the medicines and reagents are conventional medicines.

[0060] The anaerobic deionized water in this invention is oxygen-free water. It is obtained by boiling deionized water to remove oxygen initially, cooling it, and then aerating it with nitrogen for more than 30 minutes. The oxygen-free water is prepared fresh for each use.

[0061] Example 1

[0062] The steps for synthesizing natural mineral materials for degrading fluoroquinolone antibiotics are as follows:

[0063] Prepare 1.1M Na₂S solution and 0.57M FeCl₂ solution using deionized water. Add 72mL of Na₂S solution dropwise to 120mL of FeCl₂ solution, stirring at 100rpm on a magnetic stirrer at room temperature to ensure uniform mixing. After all additions are complete, age the mixture for three days with stirring at 100rpm on a magnetic stirrer. After aging, transfer the mixture to a centrifuge bottle, tighten the cap, and centrifuge at 12000rpm for 20min using a Beckman Coulter Avanti J-26S XPI high-speed centrifuge. Immediately after centrifugation, transfer the mixture to an anaerobic incubator (YQX-II) manufactured by Shanghai Hengzi Instrument Co., Ltd. Slowly pour off the supernatant, add anaerobic-treated deionized water to the precipitate, shake to redisperse, and centrifuge again using a high-speed centrifuge. Wash the mixture eight times with anaerobic deionized water, and finally redisperse it in oxygen-free water to obtain a FeS material suspension. Wrap the suspension in aluminum foil and store it in an anaerobic incubator for later use.

[0064] Example 2

[0065] The steps for characterizing the crystal structure of natural mineral materials used to degrade fluoroquinolone antibiotics are as follows:

[0066] The FeS sample prepared in Example 1 was freeze-dried into powder using a vacuum freeze dryer. The crystal structure of the mineral powder was analyzed using an X-ray powder diffractometer (D8 ADVANCE X) manufactured by Bruker AG, Germany. X-rays (Cu-Kα rays) were provided by a copper target. The mineral powder was loaded onto a single-crystal silicon sample stage for measurement. The operating voltage was 40 kV, the operating current was 40 mA, the scan rate was 0.2° / s, the scan step size was 0.02°, and the measurement angle 2θ ranged from 10° to 80°. Figure 2 As shown in the XRD pattern, the structure of Maginotite FeS was successfully synthesized. Upon oxidation in air, FeS was transformed into structures of ferrihydrite and elemental sulfur.

[0067] Example 3

[0068] The steps for surface zeta potential analysis of natural mineral materials used to degrade fluoroquinolone antibiotics are as follows:

[0069] The FeS mother liquor prepared in Example 1 was diluted to 2 g / L with deionized water. 1 mL of the sample was added to a U-shaped capillary tube and placed in the instrument for measurement. To determine the isoelectric point of the FeS mineral, the pH of the FeS solution was adjusted to 3.0, 4.0, 5.0, and 6.0 using HCl solution. Immediately afterward, the zeta potential of the sample surface was measured using a ZEN 3500 Zetasizer Nano ZS laser particle size analyzer (Malvin Instruments Ltd., UK). The samples were allowed to equilibrate for 60 s, and the refractive index was set to 2.20 for all samples. Figure 3 As shown, within the pH range of this invention, the FeS surface exhibits a negative charge.

[0070] Example 4

[0071] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0072] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: enrofloxacin (ENR) concentration was 10 μM, and the pH value was controlled within the range of 7.0 ± 0.1 using 5 mmol / L MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentrations of FeS in the system were 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, and 5 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm using a magnetic stirrer for 4 h.

[0073] (2) During the reaction, at specific time points (0, 10, 30, 60, 90, 120, 180, 240 min), 0.8 mL of sample was taken with a pipette and mixed with 0.8 mL of quenching solution (the volume ratio of 3M HClO4 to methanol in the quenching solution was 1:16). After thorough shaking, the mixture was filtered through a polytetrafluoroethylene (PTFE) filter membrane (water-based, 0.45 μm, 25 nm) into a liquid chromatography vial for determination of the total ENR content. Figure 4 As shown, the degradation rate exhibited a pattern of initially slow, then rapid, and then decreasing again with increasing mineral concentration. After 4 hours of reaction, the degradation rates of ENR were 70.3%, 86.5%, 88.5%, 88.3%, 89.7%, 87.8%, 62.9%, and 30.4%, respectively. ENR was rapidly adsorbed onto the mineral surface, with only a small portion remaining in the solution.

[0074] Example 5

[0075] The particle size distribution of the samples during the reaction was analyzed using a ZEN 3500 Zetasizer Nano ZS laser particle size analyzer. The FeS mother liquor prepared in Example 1 was diluted with MOPS buffer to 0.5 g / L and 0.05 g / L, respectively, with the pH controlled within the range of 7.0 ± 0.1. One mL of the sample was added to a U-shaped capillary tube for particle size distribution analysis. Additionally, for the 0.05 g / L FeS mineral, a separate sample was added to ENR at a final concentration of 10 μM, mixed thoroughly, and one mL of the mixture was used for particle size analysis. All sample particle size distribution data were measured in triplicate. Figure 5 As shown, there was no significant difference in particle size distribution between the two concentrations of minerals, but the particle size distribution of the system increased significantly after the addition of ENR. These experimental results indicate that the addition of ENR reduces the electrostatic repulsion between minerals, suggesting that ENR is adsorbed onto the surface of FeS mineral particles via electrostatic forces.

[0076] Example 6

[0077] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0078] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: enrofloxacin concentration was 10 μM, and the pH value was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentrations of FeS in the system were 0.05, 0.2, 0.5, and 1 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h.

[0079] (2) The changes in dissolved oxygen content during the reaction under different mineral concentrations were measured using an Orion 5STAR (Thermo Fisher Scientific) panel equipped with an Orion 081010MD dissolved oxygen electrode (Thermo Fisher Scientific, USA). Before the reaction began (without the addition of FeS), the solution was thoroughly stirred to ensure complete dissolution of oxygen. Figure 6 As shown, the addition of FeS led to a rapid decrease in dissolved oxygen content to varying degrees within minutes. As the reaction proceeded, the dissolved oxygen content gradually recovered. The ENR degradation rate was correlated with the trend of dissolved oxygen content changes, indicating that dissolved oxygen content is crucial in this invention. Based on the above data analysis, the characteristics of ENR degradation with FeS concentration in this system can be explained: For low-concentration FeS ([FeS]0 ≤ 0.2 g / L), reactant concentration and reaction sites are the main factors limiting the reaction rate, and the reaction kinetics exhibit pseudo-first-order reaction kinetics characteristics. However, as the mineral concentration further increases ([FeS]0 > 0.2 g / L), mineral concentration and reaction sites are no longer limiting factors; the dissolved oxygen content in the system becomes the important factor limiting the reaction rate. The addition of excessive FeS minerals will consume a large amount of dissolved oxygen, thus limiting the rate of the ENR oxidation process, which also requires oxygen. Considering all factors, 0.05 g / L FeS was selected as the optimal concentration.

[0080] Example 7

[0081] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0082] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: enrofloxacin concentration was 10 μM, and the pH was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentration of FeS in the system was 0.05 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h.

[0083] (2) To characterize the crystal form changes of the minerals during the reaction, 15 mL samples were taken at 0, 30, 60, 120, and 240 min, respectively. These samples were immediately centrifuged at 12000 rpm for 20 min. After centrifugation, the samples were immediately transferred to an anaerobic incubator, the supernatant was discarded, and the remaining solid was freeze-dried to powder using a vacuum freeze dryer. The crystal form was determined using an X-ray powder diffractometer (D8 ADVANCE X) manufactured by Bruker GmbH, Germany. Figure 7As shown, the characteristic peak intensity of FeS gradually decreases, and lepidocrocite and sharply shaped elemental sulfur gradually form. These experimental results indicate that during the oxidative degradation of ENR, the transformation of the FeS mineral itself is consistent with its own oxidative transformation in an air atmosphere; iron is mainly converted to lepidocrocite, and sulfur is converted from S… 2- It is transformed into the form of elemental sulfur.

[0084] Example 8

[0085] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0086] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: enrofloxacin concentration was 10 μM, and the pH was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentration of FeS in the system was 0.05 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h.

[0087] (2) The synthesized FeS minerals were characterized using a field emission scanning electron microscope (SEM, QUANTA FEG 250) equipped with an energy-dispersive X-ray spectrometer (EDS) manufactured by FEI Corporation, USA. Additionally, to characterize the changes in mineral surface morphology during degradation, 10 mL samples were centrifuged at 12000 rpm for 20 min at 0, 30, 60, 120, and 240 min. Immediately after centrifugation, the samples were transferred to an anaerobic incubator, the supernatant was discarded, and the remaining solid was freeze-dried to powder using a vacuum freeze dryer. The surface morphology of the minerals at different reaction times was then analyzed using a scanning electron microscope. For example... Figure 8 As shown, before the reaction begins, the morphology of FeS at both magnifications is amorphous with poor crystal structure, and the particle size varies from tens to hundreds of micrometers after powder agglomeration. After the reaction begins, lamellar lepidocrocite can be observed forming on the surface of FeS in the mineral. From 60 min onwards, rhombic or spindle-shaped orthorhombic sulfur (α-S8) crystal structures appear in the solid-state SEM images. Combined with the XRD characterization results in Example 7, this indicates that the FeS mineral transforms into lepidocrocite and generates elemental sulfur during the oxidative degradation of ENR.

[0088] Example 9

[0089] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0090] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: enrofloxacin concentration was 10 μM, and the pH was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentration of FeS in the system was 0.05 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h.

[0091] (2) The changes in the concentrations of dissolved ferrous iron (Fe2+) and total ferrous iron (Fe2+) in the system during the reaction were determined using the phenoxyzine colorimetric method. The phenoxyzine colorimetric reagent was dissolved in 5 mM MOPS buffer (pH = 7.0) at a concentration of 5 g / L. Samples of 2 mL were taken at 0, 10, 30, 60, 90, 120, 180, and 240 min, respectively, and immediately filtered through a 0.22 μm nylon membrane. 0.96 mL of the filtrate was mixed with 40 μL of the prepared colorimetric reagent, rapidly shaken, and allowed to develop for at least 30 min to obtain the solution of ferrous iron ions. To determine the total ferrous iron concentration in the system, 0.1 mL of the sample was simultaneously taken, and 0.9 mL of 5 M HCl solution was added. After rapid shaking to ensure complete dissolution of the minerals, the sample was immediately filtered through a 0.22 μm nylon membrane. 0.96 mL of the filtrate was mixed with 40 μL of the prepared colorimetric reagent, rapidly shaken, and allowed to develop for at least 30 min to obtain the total ferrous iron ion sample. The ferrous ion standard curve was prepared using a serially diluted stock solution of ferrous ammonium sulfate hexahydrate. 0.96 mL of the standard solution was mixed with 40 μL of pre-prepared colorimetric reagent, rapidly shaken, and allowed to develop for at least 30 minutes. 0.2 mL of the developed sample was added to a 96-well plate, and the absorbance at 562 nm was measured using a microplate reader. The ferrous ion concentration was calculated from the standard curve. Changes in total iron concentration were analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES, PQ9000) manufactured by Jena Analytical Instruments AG, Germany. For each ferrous ion concentration measurement, a 2 mL sample was simultaneously filtered through a 0.22 μm nylon membrane to determine the total iron ion concentration in solution. An additional 1 mL sample was taken to determine the total iron ion concentration of the entire system. Figure 9 As shown, the total Fe(II) concentration began to decrease slowly as the reaction proceeded, while the dissolved oxygen concentration in the solution began to rise during this process, and the Fe(II) oxidation rate gradually accelerated. This trend is consistent with the degradation trend of ENR. The total iron content of the system remained essentially unchanged, and no significant iron dissolution was observed. The Fe(II) in the mineral was ultimately almost entirely converted to Fe(III), existing as FeOOH in ferrihydrite. These experimental results demonstrate that Fe(II) oxidation induces the degradation of ENR.

[0092] Example 10

[0093] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0094] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: enrofloxacin concentration was 10 μM, and the pH was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentration of FeS in the system was 0.05 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h.

[0095] (2) An ion chromatograph (ICS-900) manufactured by Dionex Corporation (USA) was used to determine the anions in the system. It was equipped with an autosampler and an anion exchange column (Dionex IonPac AS23, 4mm × 250mm). The mobile phase used in the ion chromatography contained 10mM sodium carbonate and 1.6mM sodium bicarbonate, with a flow rate of 1.0mL / min and a sample determination time of 25min. A standard curve was prepared using sodium sulfate pentahydrate, sodium sulfite, and sodium thiosulfate. The prepared standard curve R... 2 All values ​​were greater than 0.99. During the reaction, at 0, 10, 30, 60, 90, 120, 180, and 240 min, 10 mL samples were taken using a pipette and immediately filtered through a 0.22 μm nylon membrane. The filtered samples were then pretreated with a sample pretreatment column activated with methanol and deionized water to remove organic matter and heavy metal ions. The samples were then slowly passed through a P column, an RP column, and a Na column sequentially. The filtrate was collected using an ion chromatography vial and then loaded for analysis. Figure 10 As shown, the concentrations of both sulfite and sulfate ions increased slowly during the reaction. Sulfate ions, as a product of further oxidation of sulfite, showed a slow upward trend in concentration throughout the process. However, calculations based on the concentrations revealed that almost all the sulfur in FeS was converted into elemental sulfur, with the other two forms present in negligible amounts. These experimental results indicate that during the oxidation of FeS, elemental sulfur is converted into elemental sulfur, sulfite ions, and sulfate ions.

[0096] Example 11

[0097] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0098] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: enrofloxacin concentration was 10 μM, and the pH value was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentration of FeS in the system was 0.05 g / L. The reaction was carried out at room temperature under anaerobic / air conditions, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h. To study the difference in reaction process under nitrogen atmosphere (anaerobic conditions, the reaction system was prepared with anaerobic water) and air atmosphere, for the anaerobic experiment under nitrogen atmosphere, the deionized water used in the experiment was initially boiled to remove oxygen, and after cooling, it was aerated with nitrogen for more than 30 min to obtain anaerobic water, which was prepared fresh for each use. During the reaction, nitrogen was continuously introduced into the anaerobic group to maintain the anaerobic system.

[0099] (2) During the reaction, at specific time points (0, 10, 30, 60, 90, 120, 180, 240 min), 0.8 mL of sample was taken with a pipette and mixed with 0.8 mL of quenching solution (the volume ratio of 3M HClO4 to methanol in the quenching solution was 1:16). After thorough shaking, the mixture was filtered through a polytetrafluoroethylene (PTFE) membrane (water-based, 0.45 μm, 25 nm) into a liquid chromatography vial to determine the total ENR content. Simultaneously, 1.6 mL of sample was taken with a pipette and directly filtered through a PTFE membrane into a liquid chromatography vial. 20 μL of 3M HClO4 was added for acidification, and the content of ENR in the solution was determined. Figure 11 As shown, under a nitrogen atmosphere, the low dissolved oxygen content significantly inhibited the degradation of ENR, indicating that oxygen plays a crucial role in the reaction.

[0100] Example 12

[0101] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0102] (1) The experimental conditions for the degradation of fluoroquinolone antibiotics were as follows: the concentration of enrofloxacin was 10 μM, and FeS prepared in Example 1 was added to the antibiotic solution, with a final concentration of 0.05 g / L in the system. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h. To study the effect of pH, the pH value was controlled within the range of 7.0 ± 0.1 using 5 mM M OPS, 5 mM acetate-sodium acetate buffer to control pH = 5.0 ± 0.1 using 5 mM 2-cyclohexylaminoethanesulfonic acid (CHES) buffer to control pH = 9.0 ± 0.1.

[0103] (2) During the reaction, at specific time points (0, 10, 30, 60, 90, 120, 180, 240 min), 0.8 mL of sample was taken with a pipette and mixed with 0.8 mL of quenching solution (the volume ratio of 3M HClO4 to methanol in the quenching solution was 1:16). After thorough shaking, the mixture was filtered through a polytetrafluoroethylene (PTFE) membrane (water-based, 0.45 μm, 25 nm) into a liquid chromatography vial to determine the total ENR content. Simultaneously, 1.6 mL of sample was taken with a pipette and directly filtered through a PTFE membrane into a liquid chromatography vial. 20 μL of 3M HClO4 was added for acidification, and the content of ENR in the solution was determined. Figure 12 As shown (different batches from Example 4), after a reaction of 4 hours, the degradation rates of ENR at different pH levels (5.0, 7.0, 9.0) were 37.1%, 87.7%, and 63.4%, respectively. The above experimental results indicate that this method can efficiently degrade FQs within a certain pH range, and the effect is best at pH 7.0.

[0104] Example 13

[0105] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0106] (1) The experimental conditions for the degradation of fluoroquinolone antibiotics were as follows: the concentration of enrofloxacin was 10 μM, and FeS prepared in Example 1 was added to the antibiotic solution, with a final concentration of 0.05 g / L in the system. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h. To study the effect of pH, the pH value was controlled within the range of 7.0 ± 0.1 using 5 mM M OPS, pH = 5.0 ± 0.1 using 5 mM acetate-sodium acetate buffer, and pH = 10.0 ± 0.1 using 5 mM 2-cyclohexylaminoethanesulfonic acid (CHES) buffer.

[0107] (2) To characterize the crystal form changes of the minerals during the reaction, 15 mL samples were taken at 0, 60, 120, and 240 min, respectively. These samples were immediately centrifuged at 12000 rpm for 20 min using a high-speed centrifuge. After centrifugation, the samples were immediately transferred to an anaerobic incubator, the supernatant was discarded, and the remaining solid was freeze-dried to powder using a vacuum freeze dryer. The crystal form was determined using a Bruker D8 ADVANCE X XRD instrument. Figure 13 As shown, when pH changes, FeS is still mainly converted into elemental sulfur and the structure of ferrihydrite. Compared with the mineral transformation at pH 7.0, the mineral transformation rate is slower at pH 5.0, and no significant change is observed in mineral transformation at pH 9.0.

[0108] Example 14

[0109] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0110] (1) The experimental conditions for the degradation of fluoroquinolone antibiotics were as follows: the concentrations of enrofloxacin, ciprofloxacin, flumethylquine, and 1-(2-fluorophenyl)piperazine were 10 μM, and the pH was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the antibiotic solution, and the final concentration of FeS in the system was 0.05 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h.

[0111] (2) During the reaction, at specific time points (0, 10, 30, 60, 90, 120, 180, 240 min), 0.8 mL of sample was taken with a pipette and mixed with 0.8 mL of quenching solution (the volume ratio of 3M HClO4 to methanol in the quenching solution was 1:16). After thorough shaking, the mixture was filtered through a polytetrafluoroethylene (PTFE) membrane (water-based, 0.45 μm, 25 nm) into a liquid chromatography vial for total volume determination. Simultaneously, 1.6 mL of sample was taken with a pipette and directly filtered through a PTFE membrane into a liquid chromatography vial. 20 μL of 3M HClO4 was added for acidification, and the solution content was determined. For example... Figure 14 As shown, the present invention can achieve a degradation effect of more than 80% on FLU, ENR and CIP, and the overall degradation rate is FLU>ENR>CIP>FPP. FeS has a good degradation effect on fluoroquinolone antibiotics.

[0112] Example 15

[0113] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0114] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: the concentrations of enrofloxacin, ciprofloxacin, flumethylquine, and 1-(2-fluorophenyl)piperazine were 10 μM; the pH was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS; FeS prepared in Example 1 was added to the antibiotic solution, and the final concentration of FeS in the system was 0.05 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h. At the beginning of the reaction in each system, 100 mM tert-butanol (TBA) was added to quench hydroxyl radicals, 100 mM sodium fluoride (NaF) was added to complex trivalent iron on the mineral surface, 100 mM KI was added to quench surface hydroxyl radicals, 2,2'-bipyridine was added to chelate divalent iron ions, nitrotetrazolium chloride (NBT) was added to quench superoxide anion radicals, and peroxidase (CAT) was added to quench hydrogen peroxide.

[0115] (2) During the reaction, at specific time points (0, 10, 30, 60, 90, 120, 180, 240 min), 0.8 mL of sample was taken with a pipette and mixed with 0.8 mL of quenching solution (the volume ratio of 3M HClO4 to methanol in the quenching solution was 1:16). After thorough shaking, the mixture was filtered through a polytetrafluoroethylene (PTFE) membrane (water-based, 0.45 μm, 25 nm) into a liquid chromatography vial to determine the total ENR content. Simultaneously, 1.6 mL of sample was taken with a pipette and directly filtered through a PTFE membrane into a liquid chromatography vial. 20 μL of 3M HClO4 was added for acidification, and the content of ENR in the solution was determined. Figure 15 As shown, TAB slightly inhibits the degradation of ENR, proving the presence of hydroxyl radicals in the system. The addition of KI significantly inhibited ENR degradation, indicating that surface hydroxyl radicals play an important role in the reaction. The addition of NaF had no effect on the reaction rate and also had no significant effect on ENR adsorption, indicating that the ferric iron in the ferrihydrite formed by FeS oxidation does not act as a reaction site affecting the reaction. The CAT group showed that the generation of hydroxyl radicals was directly inhibited by quenching hydrogen peroxide, indicating that hydrogen peroxide was generated and involved in the oxidation process. NBT, as a superoxide anion radical quencher, had a very significant quenching effect on the system, indicating that superoxide anion radicals are also a very important ROS generated in this process. BPY significantly inhibited the adsorption and oxidation of ENR by FeS, indicating that ferrous iron, while acting as an adsorption site, is also an important reaction site in this reaction. The above experimental results indicate that both the superoxide anion radicals and hydroxyl radicals generated by ferrous oxidation are reactive oxygen species that degrade ENR.

[0116] Example 16

[0117] A method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials, comprising the following steps:

[0118] (1) The cumulative amount of hydroxyl radicals generated in the system was determined using the benzoic acid (BA) method. The experimental conditions for benzoic acid degradation were as follows: the pH value was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS, and the concentration of benzoic acid was 10 mM. FeS prepared in Example 1 was added to the solution, and the final concentration of FeS in the system was 0.05 and 0.5 g / L. The reaction was carried out at room temperature in air, and the reaction solution was continuously stirred at 150 rpm with a magnetic stirrer for 4 h. The amount of hydroxyl radicals generated in the system was calculated by measuring the content of p-hydroxybenzoic acid (p-HBA) generated during the reaction.

[0119] (2) During the reaction, at specific time points (0, 10, 30, 60, 90, 120, 180, 240 min), 0.8 mL of sample was taken with a pipette and mixed with 0.8 mL of quenching solution (the volume ratio of 3M HClO4 to methanol in the quenching solution was 1:16). After thorough shaking, the mixture was filtered through a polytetrafluoroethylene (PTFE) filter membrane (water-based, 0.45 μm, 25 nm) into a liquid chromatography vial for determination of the total BA content. Figure 16 As shown, the amount of hydroxyl radicals increases linearly under both mineral concentrations; the higher the mineral concentration, the greater the amount of hydroxyl radicals produced and the faster the rate. These experimental results demonstrate that hydroxyl radicals are generated in the FeS oxidation system, but fewer hydroxyl radicals are produced at low FeS concentrations.

[0120] Example 17

[0121] (1) The amount of superoxide anion radical generated was determined by the XTT method. The initial concentration of XTT was 0.05 mM. The pH value was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS. FeS prepared in Example 1 was added to the XTT solution. The final concentrations of FeS in the system were 0.05, 0.2, 0.5, and 1 g / L. The pH value was controlled at around 7.0 using MOPS buffer. The reaction was carried out at room temperature. The reaction solution was continuously stirred at 150 rpm using a magnetic stirrer for 4 h.

[0122] (2) During the reaction, at specific time points (0, 10, 30, 60, 90, 120, 180, 240 min), 0.8 mL of sample was taken with a pipette and mixed with 0.8 mL of quenching solution (the volume ratio of 3M HClO4 to methanol in the quenching solution was 1:16). After thorough shaking, the mixture was filtered through a polytetrafluoroethylene (PTFE) membrane (water-based, 0.45 μm, 25 nm). The absorbance of the solution at 475 nm was measured using a UV-Vis spectrophotometer (Cary 50) manufactured by Agilent Technologies, USA. The concentration of XTT formazan in the solution was obtained according to the Lambert-Beer law. Figure 17 As shown, the higher the mineral concentration, the lower the dissolved oxygen content in the system, and the lower the production amount and rate of superoxide anion free radicals. However, more superoxide anion free radicals are produced at low FeS concentrations, indicating that superoxide anion free radicals play an important role in degradation.

[0123] Example 18

[0124] Analysis was performed using an A300-6 / 1 electron paramagnetic resonance spectrometer manufactured by Bruker Technologies, Germany. Before measurement, the FeS sample prepared in Example 1 was diluted with ultrapure water to concentrations of 0.001 g / L, 0.005 g / L, and 0.05 g / L. Then, 180 μL of each sample was taken, and 20 μL of 5,5-dimethyl-1-pyrrolline-N-oxide (DMPO) was added. The mixture was rapidly shaken to ensure sufficient contact between the FeS mineral and oxygen. The sample was then aspirated using a capillary tube, sealed with paraffin, and placed in the electron paramagnetic resonance spectrometer for analysis. Signals were superimposed three times. Figure 18 As shown, the fine structure of hydroxyl radicals with quartets was clearly observed in the EPR spectrum, indicating that hydroxyl radicals were generated in the FeS oxidation system, promoting the degradation of ENR.

[0125] Example 19

[0126] (1) The experimental conditions for degrading fluoroquinolone antibiotics were as follows: the concentration of enrofloxacin was 10 μM, the pH value was controlled within the range of 7.0 ± 0.1 using 5 mM MOPS, and FeS prepared in Example 1 was added to the solution, with a final concentration of 0.05 g / L in the system. The reaction time was 4 h.

[0127] (2) During the reaction, 5 mL samples were taken at specific time points (0, 30, 60, 120, and 240 min) using a pipette. The samples were purified and enriched using a Waters Oasis HLB cartridge (Waters Corporation, USA). Mass spectrometry data were collected using a high-performance liquid chromatography-time-of-flight mass spectrometer (HPLC-TOF-MS) to analyze the reaction products. The HPLC system was equipped with an Atlantis T3 2.1 × 100 mm, 3 μm column (Waters Corporation, USA) to separate substances in the samples. Figure 19 As shown, the superoxide anion radical and hydroxyl radical in the system steal electrons from the N atom of the piperazine ring and the carbon-carbon double bond of the quinolone structure through radical attack and electrophilic attack, forming positive ion radicals. Further oxidation leads to the ring-opening cleavage of the piperazine ring and the quinolone structure.

Claims

1. A method for efficient degradation of fluoroquinolone antibiotics using natural mineral materials, characterized by, The method comprises the following steps: (a) synthesizing natural ferrous sulfide minerals; (b) adding the synthesized ferrous sulfide minerals into a fluoroquinolone antibiotic solution, adjusting the pH of the reaction by using buffer salt, uniformly stirring under air condition, and performing a degradation reaction of the fluoroquinolone antibiotic; The specific steps for synthesizing the natural ferrous sulfide minerals in step (a) are as follows: (1) adding a Na2S solution into a FeCl2 solution under anaerobic condition; (2) stirring and aging the solution in step (1) under anaerobic condition; (3) centrifuging the solution after aging in step (2), discarding the supernatant, and obtaining a precipitate; (4) adding anaerobic water into the precipitate under anaerobic condition, and then oscillating and redispersing the precipitate; (5) centrifuging the redispersed solution, discarding the supernatant, and obtaining a precipitate; (6) repeating steps (4)-(5), redispersing the washed precipitate with anaerobic water, and storing the precipitate under anaerobic condition for standby use; In step (b), the pH of the reaction system is controlled in the range of 7.0±0.1, the amount of the ferrous sulfide minerals added into the fluoroquinolone antibiotic solution is 0.05 g / L, the concentration of the fluoroquinolone antibiotic is 10 μM, and the reaction time is 4 h; when the concentration of the minerals is low, the production amount and rate of superoxide anion free radicals in the system are high, and the production amount and rate of hydroxyl free radicals are low.

2. The method for efficient degradation of fluoroquinolone antibiotics using natural mineral materials according to claim 1, characterized in that, In step (1), the molar ratio of Na2S to FeCl2 is 1-1.5:

1. 3.The method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials according to claim 1, characterized in that, In step (2), the stirring rate is 100-200 rpm, and the stirring and aging time at room temperature is 60-80 h. 4.The method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials according to claim 1, characterized in that, In step (6), the number of times of repeating steps (4)-(5) is 5-8 times. 5.The method for efficiently degrading fluoroquinolone antibiotics using natural mineral materials according to claim 1, characterized in that, In step (b), 3-morpholinopropanesulfonic acid buffer (MOPS) is used to control the pH of the reaction system in the range of 7.0±0.1.

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