A magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics and its preparation method.

Abstract

This invention discloses a magnetic FeS2 / biochar material for activating the degradation of antibiotics by peracetic acid and its preparation method. Biochar raw materials and an iron-sulfur source are mixed and stirred under a nitrogen atmosphere. The resulting solution is transferred to a reaction vessel and heated at a fixed temperature. After the reaction, the solid phase is filtered, washed several times with ultrapure water, dried, cooled, and then ground in a mortar. The solid is dispersed in a crucible and heated at a fixed temperature. After natural cooling, it is ground in a mortar to obtain the magnetic FeS2 / biochar material. This invention, through precise control of the iron-sulfur source concentration and temperature, is simpler and easier to control than general modification methods. It exhibits a more efficient PAA degradation activation capacity than the original biochar material. The preparation process is simple, parameters are easily controlled, and no complex post-processing steps are required. It combines high-efficiency pollutant degradation performance and cycle stability, and can be quickly recovered via magnetic attraction after use.

Description

Technical Field

[0001] This invention relates to the field of catalysis technology, specifically to a magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics and its preparation method. Background Technology

[0002] Antibiotics, due to their widespread use, are emerging as a threat to environmental safety and human health. Traditional advanced oxidation processes (AOPs) primarily rely on hydroxyl radicals (HO radicals). • ) or sulfate free radicals (SO4) •− While oxidation reactions can be performed using peracetic acid (PAA), problems such as low oxidant utilization and potential secondary pollution from metal catalysts remain. PAA is considered an emerging oxidant in advanced oxidation processes because it shares the same O / O bond structure as peroxymonosulfate (PMS), peroxydisulfate (PDS), and hydrogen peroxide (H₂O₂). Furthermore, PAA exhibits O / O bond cleavage (170 kJ / mol). −1 Its low activation energy makes it easy to activate and gives it an advantage in pollutant decay, but its targeted degradation efficiency when used alone is limited by the free radical generation rate and mass transfer efficiency.

[0003] Biochar possesses an adjustable specific surface area and abundant surface functional groups, exhibiting high catalytic activity for various peroxides such as hydrogen peroxide, PMS, and PAA. However, pristine biochar exhibits limited catalytic activity and durability due to insufficient active sites and low electron transfer efficiency. Therefore, it is necessary to appropriately modify biochar to improve its activation performance for PAA. Studies have shown that loading iron or its compounds onto biochar to synthesize iron-based biochar can not only significantly improve the activation performance of PAA but also significantly reduce the generation of free iron ions, greatly enhancing the effectiveness of the activator.

[0004] Iron-based biochar-catalyzed peracetic acid production has attracted widespread attention due to its strong oxidizing power and environmentally friendly characteristics. However, the Fe content in the catalyst... 3+ To Fe 2+ The slow conversion rate significantly limited the activation efficiency of PAA. Secondly, the high concentration of Fe... 2+ It may reduce reactive oxygen species (such as hydroxyl radicals HO) in the system through the free radical quenching effect. • The concentration of Fe2+ can weaken the degradation effect on pollutants. These factors collectively limit the application potential of iron-based biochar catalysts in practical water treatment. Therefore, optimizing Fe2+ concentrations is crucial. 2+ / Fe 3+ The cycle efficiency is key to improving the performance of this process.

[0005] A significant challenge in the application of nanocatalysts in water remediation is their solution separation performance. Although biochar materials exhibit excellent catalytic activity, their efficient separation from the aqueous phase after reaction is difficult, limiting their practical application. To address this issue, researchers successfully synthesized modified biochar materials with ideal physicochemical properties by introducing multivalent transition metals (such as iron, cobalt, and copper) as additives. These embedded magnetic metal particles not only enhance the catalytic performance of the material but also endow it with excellent magnetic response characteristics. Under the action of an external magnetic field, the magnetic biochar catalyst can be rapidly separated from the solution, significantly simplifying the recovery process and avoiding the cumbersome operations of traditional solid-liquid separation techniques.

[0006] This patent addresses the aforementioned problems by precisely controlling the molar concentration of the iron-sulfur source and the calcination temperature, using a hydrothermal and calcination method to synthesize Fe / S-BC-750, and achieving efficient removal of organic pollutants from water by activating PAA. The aim is to establish a simple, efficient, stable, and easily recyclable deep treatment technology for organic pollutants. Summary of the Invention

[0007] Therefore, the present invention aims to provide a magnetic FeS2 / biochar material for activating the degradation of antibiotics by peracetic acid and its preparation method. The material has a simple synthesis process, higher activity and stability in activating the degradation of antibiotics by PAA, and can be quickly recovered by magnetic attraction after use.

[0008] This invention provides a magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics and its preparation method, comprising the following steps:

[0009] (A) Mix and stir the biochar raw material and the iron-sulfur source under a nitrogen atmosphere;

[0010] (B) The solution obtained above is transferred into a reaction vessel and heated at a fixed temperature. After the reaction is completed, the solid phase is separated by filtration, washed several times with ultrapure water, dried and cooled, and then ground in a mortar and pestle.

[0011] (C) The above solids are dispersed in a crucible and heated at a fixed temperature. After natural cooling, they are ground in a mortar to obtain magnetic FeS2 / biochar material, which is labeled as Fe / S-BC-750.

[0012] Preferably, the biochar raw material is *Chongyang* wood powder, the iron and sulfur source is ferrous sulfate heptahydrate, and the molar concentration of ferrous sulfate heptahydrate is 0.5 mol / L.

[0013] Preferably, the reaction in step (B) is carried out in a reaction vessel at a temperature of 180 °C for a time of 24 h.

[0014] Preferably, the reaction in step (C) is carried out in a muffle furnace at a temperature of 750 °C for a time of 1 h.

[0015] The technical solution of this invention has the following advantages:

[0016] This invention provides a magnetic FeS2 / biochar material (Fe / S-BC-750) with precise proportional temperature control and high efficiency in activating PAA degradation, and its preparation method.

[0017] Fe / S-BC-750 was synthesized by controlling specific temperatures and reagent ratios through hydrothermal and calcination treatments. Precise control over the chemical composition of the material was achieved under conditions of a ferrous sulfate heptahydrate molar concentration of 0.5 mol / L, a hydrothermal temperature of 180 ℃, and a calcination temperature of 750 ℃. The material is matched with standard cards FeS2 PDF#99-0076 and Fe3O4 PDF#75-0449. Its layered porous structure is beneficial for increasing specific surface energy, thus facilitating the degradation of antibiotics in water.

[0018] Iron-based supported biochar catalysts generate hydroxyl radicals (HO radicals) through the reaction of iron species (such as Fe²⁺, Fe³⁺) with PAA. • ), superoxide radicals (O2) •- ), organic free radicals (RO) • ), thereby degrading organic pollutants in the water, but Fe 3+ To Fe 2+ The low conversion efficiency of Fe³⁺ limits the activation efficiency of PAA. Fe / S-BC-750 introduces reducing sulfur compounds to improve the conversion rate of Fe³⁺ to Fe²⁺, significantly enhancing the activation efficiency of PAA and promoting the activation of various reactive species (such as superoxide radicals (O₂)). •- Acetoxy radical (CH3COO) • ) and singlet oxygen ( 1 The generation of O2. These active species can efficiently degrade organic pollutants in water while avoiding secondary pollution from metal catalysts. In addition, magnetic Fe3O4 loaded on biochar effectively solves the problem of difficult biochar recovery.

[0019] The preparation method of the present invention is simple to operate, has high synthesis efficiency, and exhibits high PAA degradation performance and good catalyst stability. Attached Figure Description

[0020] Figure 1a The catalyst prepared in Example 1 was activated to study the PAA degradation kinetics of SMX.

[0021] Figure 1bThe catalyst prepared in Example 2 was activated to study the PAA degradation kinetics of SMX.

[0022] Figure 1c The curves show the degradation of SMX by PAA activated by Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3, respectively.

[0023] Figure 2a The curves show the activation of PAA and degradation of SMX by Fe / S-BC-750 prepared in Example 1 under different catalyst dosages.

[0024] Figure 2b The curves show the activation of PAA and degradation of SMX by Fe / S-BC-750 prepared in Example 1 under different PAA dosage conditions.

[0025] Figure 3 The images show SEM and TEM images of Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3, respectively, and the elemental distribution diagram of Fe / S-BC-750.

[0026] Figure 4 Isotherm diagrams of Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3, respectively.

[0027] Figure 5 Tafel plots and electrochemical impedance spectroscopy of Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3, respectively.

[0028] Figure 6 The curves of PAA degradation of SMX by Fe / S-BC-750 prepared in Example 1 under different pH conditions.

[0029] Figure 7 The bar chart shows the activation of PAA and degradation of SMX by Fe / S-BC-750 prepared in Example 1 under different anion concentrations and the influence of natural organic matter.

[0030] Figure 8 This is a diagram showing the recycling of SMX by Fe / S-BC-750 activated PAA prepared in Example 1.

[0031] Figure 9 The hysteresis loop of Fe / S-BC-750 prepared in Example 1. Detailed Implementation

[0032] To further describe the invention, the following detailed description, with reference to examples, provides a magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics and its preparation method. Example

[0033] 6.0 g of uniformly ground *Bischofia javanica* powder was mixed with 50 mL of FeSO4·7H2O (0.5 mol / L) under a nitrogen atmosphere and stirred for 1 h. The mixture was then transferred to a high-pressure reactor and hydrothermally heated at 180 °C for 24 h. After the reaction was complete, the solid phase was separated by filtration, washed several times with ultrapure water, dried at 80 °C, and cooled to obtain the hydrothermal carbon precursor Fe / S-BC.

[0034] Fe / S-BC was placed in a muffle furnace and heated at a rate of 10 °C / min until it reached 750 °C and was held for 1 h.

[0035] After naturally cooling to room temperature, the sample in the crucible was transferred to a mortar and ground. The resulting solid product was named Fe / S-0.5-BC-750.

[0036] Keeping the heating rate and synthesis temperature of the sample constant in the muffle furnace, the molar concentration of ferrous sulfate heptahydrate was adjusted to 0.10 mol / L, 0.25 mol / L, 0.75 mol / L, and 1.00 mol / L, respectively. The other steps were the same, and the resulting products were named Fe / S-0.10-BC-750, Fe / S-0.25-BC-750, Fe / S-0.75-BC-750, and Fe / S-1.00-BC-750. Example

[0037] 6.0 g of uniformly ground *Bischofia javanica* powder was mixed with 50 mL of FeSO4·7H2O (0.5 mol / L) under a nitrogen atmosphere and stirred for 1 h. The mixture was then transferred to a high-pressure reactor and hydrothermally heated at 180 °C for 24 h. After the reaction was complete, the solid phase was separated by filtration, washed several times with ultrapure water, dried at 80 °C, and cooled to obtain the hydrothermal carbon precursor Fe / S-BC.

[0038] Fe / S-BC was placed in a muffle furnace and heated at a rate of 10 °C / min until it reached 750 °C and was held for 1 h.

[0039] After naturally cooling to room temperature, the sample in the crucible was transferred to a mortar and ground. The resulting solid product was named Fe / S-BC-750.

[0040] Keeping the molar concentration of ferrous sulfate heptahydrate in the synthesized sample at 0.5 mol / L and the heating rate in the muffle furnace at 10 ℃ / min constant, the muffle furnace temperature was adjusted to 600 ℃ and 900 ℃, and the other steps were the same. They were named Fe / S-BC-600 and Fe / S-BC-900, respectively.

[0041] Figure 1a-b indicates that the Fe / S-BC-750 catalyst prepared under the conditions of FeSO4•7H2O molar concentration of 0.5 mol / L, heating rate of 10 ℃ / min, and holding at 750 ℃ ​​for 1 h has the highest degradation efficiency for SMX-activated PAA degradation. Example

[0042] 6.0 g of uniformly ground *Bischofia javanica* powder was mixed with 50 mL of ultrapure water and stirred for 1 h. The mixture was then transferred to a high-pressure reactor and hydrothermally heated at 180 °C for 24 h. After the reaction was completed, the solid phase was separated by filtration, washed several times with ultrapure water, dried and cooled at 80 °C to obtain the hydrothermal carbon precursor.

[0043] The above product was placed in a muffle furnace and heated at a rate of 10 °C / min until it reached 750 °C and was held for 1 h.

[0044] After naturally cooling to room temperature, the sample in the crucible was transferred to a mortar and ground. The resulting solid product was named BC-750.

[0045] according to Figure 1a The degradation effect of the -b catalyst on SMX shows that the activation of PAA for SMX degradation is most significant when the Fe / S-BC-750 preparation conditions are: 0.5 mol / L ferrous sulfate heptahydrate and 750 ℃.

[0046] according to Figure 1c The degradation effect of the catalyst on SMX showed that, compared with BC-750, the prepared Fe / S-BC-750 activated PAA had a more significant effect on SMX degradation.

[0047] according to Figure 2a -b Catalyst under different dosages and PAA concentrations, Fe / S-BC-750 activated PAA degradation SMX curves. Considering reaction cost and efficiency, compared with other reaction conditions, the activated PAA degradation of SMX is more green and efficient when the catalyst dosage is 0.2 g / L and the PAA concentration is 0.3 mM.

[0048] according to Figure 3The results showed that BC-750 exhibited an irregular layered structure with a porous surface conducive to organic adsorption, but Fe / S modification significantly enhanced pore formation, indicating improved mass transfer capacity. BC-750 displayed a layered graphite structure with a lattice spacing of 0.248 nm, consistent with π-π stacked aromatic clusters. Fe / S-BC-750 exhibited clear lattice fringes of 0.159 nm (FeS2 (031) crystal plane) and 0.253 nm (Fe3O4 (311) crystal plane), confirming the coexistence of the two crystal phases. Energy dispersive spectroscopy elemental surface scanning analysis showed that Fe, S, and O elements were uniformly distributed on the catalyst surface, verifying the uniform dispersion of FeS2 and Fe3O4 nanoparticles.

[0049] according to Figure 4 The BET results showed that both Fe / S-BC-750 and BC-750 have large specific surface areas, which is beneficial for exposing more active sites on the material surface and for the adsorption of PAA and target pollutants on the material surface and the subsequent catalytic oxidation degradation process.

[0050] according to Figure 5 The analytical results show that the self-corrosion potential of Fe / S-BC-750 is −0.361 V, which decreases to −0.471 V after Fe / S modification, indicating that Fe / S-BC-750 has greater electron mobility. Furthermore, the EIS of Fe / S-BC-750 exhibits a smaller semi-circular diameter and better charge separation. These results suggest that the synergistic effect of Fe and S contributes to the better electrochemical performance of Fe / S-BC-750, facilitating better electron transfer.

[0051] according to Figure 6 Results at different pH levels showed that the removal rate of SMX was only slightly inhibited as the initial solution pH increased from 3.0 to 9.0. Under acidic and neutral conditions, the removal rate of SMX changed little (approximately 4%). Even under alkaline conditions (pH = 9.0), the system maintained a high SMX removal rate (approximately 73%). These results indicate that the catalytic system exhibits excellent removal efficiency over a wide pH range and strong resistance to interference.

[0052] according to Figure 7 The results showed that low concentrations of Cl − HA and HCO3 have a certain promoting effect on the removal of SMX. − and PO4 3− The addition of HCO3 inhibited the removal of SMX. − Competition with organic pollutants H2O •CO3 generation •– This inhibited the removal efficiency of organic pollutants in the activated PAA system.

[0053] according to Figure 8 The recycling results show that Fe / S-BC-750 can still remove 83% of SMX after four recycling cycles, demonstrating good material stability.

[0054] according to Figure 9 The hysteresis loop results show that Fe / S-BC-750 possesses sufficient ferromagnetism. Therefore, Fe / S-BC-75 is easily recyclable, avoiding secondary pollution to the environment.

[0055] The above-described embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics, characterized in that, Includes the following steps: (A) Mix and stir the biochar raw material and the iron-sulfur source under a nitrogen atmosphere; (B) The solution obtained above is transferred into a reaction vessel and heated at a fixed temperature. After the reaction is completed, the solid phase is separated by filtration, washed several times with ultrapure water, dried and cooled, and then ground in a mortar and pestle. (C) The above solids are dispersed in a crucible and heated at a fixed temperature. After natural cooling, they are ground in a mortar to obtain magnetic FeS2 / biochar material, which is labeled as Fe / S-BC-750. In step (A), the biochar raw material is *Chongyang* wood powder, and the iron-sulfur source is ferrous sulfate heptahydrate. The molar concentration of FeSO4·7H2O is 0.5 mol / L; In step (B), the temperature is fixed at 180 ℃ and the hydrothermal time is 24 h; In step (C), the temperature is fixed at 750 °C and the heating time is 1 h.

2. The magnetic FeS2 / biochar material Fe / S-BC-750 with the function of activating peracetic acid was prepared by the preparation method according to claim 1.

3. The application of the magnetic FeS2 / biochar material Fe / S-BC-750 according to claim 2 in the degradation of antibiotics by activated peracetic acid.

4. The application according to claim 3, characterized in that, Magnetic FeS2 / biochar material Fe / S-BC-750 is recovered by magnetic attraction.

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