Magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics and preparation method of magnetic FeS2 / biochar material

Abstract

The invention discloses a magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics and a preparation method of the magnetic FeS2 / biochar material. Mixing and stirring the biochar raw material and the iron-sulfur source under a nitrogen atmosphere condition; transferring the obtained solution into a reaction kettle, heating at a fixed temperature, after the reaction is finished, filtering and separating a solid-phase substance, washing the solid-phase substance with ultrapure water for multiple times, drying and cooling, and grinding with a mortar; and dispersing the solid in a crucible, heating at a fixed temperature, naturally cooling, and grinding by using a mortar to obtain the magnetic FeS2 / biochar material. By accurately regulating and controlling the concentration and the temperature of an iron-sulfur source, compared with a common modification method, the method is simpler and easier to regulate and control, and compared with an original biochar material, the method has more efficient PAA degradation activation capacity, the preparation process is simpler, parameters are easy to control, complex post-treatment steps are not needed, efficient pollutant degradation performance and cycle stability are achieved, and the method is suitable for industrial production. And after use, the device can be quickly recovered through magnetic attraction.

Description

Technical Field

[0001] The present invention relates to the field of catalytic technology, and particularly relates to a magnetic FeS 2 / biochar material for activating peracetic acid to degrade antibiotics and a preparation method thereof. Background Art

[0002] Due to their widespread use, antibiotics are becoming an emerging pollutant, posing a threat to environmental safety and human health. Traditional advanced oxidation processes (AOPs) mainly rely on hydroxyl radicals (HO • ·) or sulfate radicals (SO 4 •− ·) for oxidation reactions, but face problems such as low utilization rate of oxidants and possible secondary pollution caused by metal catalysts. Peracetic acid (PAA) is considered an emerging oxidant in advanced oxidation processes because it has the same O-O bond structure as peroxymonosulfate (PMS), peroxydisulfate (PDS), and hydrogen peroxide (H 2 2 2 O −1 ). In addition, the activation energy for the cleavage of the O-O bond in PAA (170 KJ mol

[0003] -1) is relatively low, making it easy to be activated and showing advantages in pollutant decay. However, its targeted degradation efficiency when used alone is limited by the free radical generation rate and mass transfer efficiency.

[0004] Biochar has an adjustable specific surface area and abundant surface functional groups, and has high catalytic activity for various peroxides such as hydrogen peroxide, PMS, and PAA. However, due to insufficient active sites and low electron transfer efficiency, raw biochar exhibits limited catalytic activity and durability. Therefore, it is necessary to appropriately modify biochar to improve its activation performance for PAA. Research shows that synthesizing iron-based biochar by loading iron or its compounds on biochar can not only significantly improve the activation performance of PAA, but also significantly reduce the generation amount of free iron ions, greatly improving the effectiveness of the activator. 3+ 2+ 2+ 3+ 2+ 3+ • · 2+ 2+ 3+The cyclic efficiency is the key to improving the performance of this process.

[0005] An important challenge in the application of nanocatalysts in the field of water remediation is their solution separation performance. Although biochar materials exhibit excellent catalytic activity, they are difficult to efficiently separate from the aqueous phase after the reaction, which limits 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, etc.) as additives. These embedded magnetic metal particles not only enhance the catalytic performance of the materials but also endow them with good 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 technologies.

[0006] In response to the above problems, this patent synthesizes Fe / S-BC-750 by hydrothermal and calcination methods through precisely regulating the molar concentration of iron and sulfur sources and the calcination temperature, and realizes the efficient removal of organic pollutants in water by activating PAA, aiming to establish a simple, efficient, stable, and easily recyclable advanced treatment technology for organic pollutants. Summary of the Invention

[0007] In view of this, the problem to be solved by the present invention is to provide a magnetic FeS 2 / biochar material for activating peracetic acid to degrade antibiotics and its preparation method. The synthesis process of this material is simple, it has higher activity and stability in activating PAA to degrade antibiotics, and it can be rapidly recovered by magnetic attraction after use.

[0008] A magnetic FeS 2 / biochar material for activating peracetic acid to degrade antibiotics and its preparation method provided by the present invention include the following steps: (A) Mix and stir the biochar raw material and the iron and sulfur sources under a nitrogen atmosphere. (B) Transfer the solution obtained above into a reaction kettle and heat it at a fixed temperature. After the reaction ends, the solid substance is separated by filtration, washed several times with ultrapure water, dried and cooled, and then ground using a mortar. (C) Disperse the above solid in a crucible and heat it at a fixed temperature. After natural cooling, grind it using a mortar to obtain the magnetic FeS 2 / biochar material, which is labeled as Fe / S-BC-750.

[0009] Preferably, the biochar raw material is Bischofia polycarpa powder, the iron and sulfur source is ferrous sulfate heptahydrate, and the molar concentration of ferrous sulfate heptahydrate is 0.5 mol / L.

[0010] Preferably, the reaction in step (B) is carried out in a reaction kettle, the reaction temperature is 180 °C, and the reaction time is 24 h.

[0011] Preferably, the reaction in step (C) is carried out in a muffle furnace, the reaction temperature is 750 °C, and the reaction time is 1 h.

[0012] The technical solution of the present invention has the following advantages: The present invention provides a magnetic FeS 2 / biochar material (Fe / S-BC-750) with precise proportional temperature regulation and high-efficiency activated PAA degradation performance and its preparation method.

[0013] Fe / S-BC-750 is synthesized by hydrothermal and calcination treatments, controlling a certain temperature and reagent ratio. Under the conditions of a molar concentration of ferrous sulfate heptahydrate of 0.5 mol / L, a hydrothermal temperature of 180 °C, and a calcination temperature of 750 °C, precise controllability of the chemical composition of the material is achieved. And it matches with the standard cards FeS 2 PDF#99-0076 and Fe 3 O 4 PDF#75-0449. The material has a layered porous structure, which is beneficial to the improvement of specific surface energy and thus beneficial to the degradation of antibiotics in water.

[0014] The iron-based supported biochar catalyst generates hydroxyl radicals (HO • ), superoxide radicals (O 2 •- ), and organic radicals (R-O • ) through the reaction of iron species (such as Fe²⁺, Fe³⁺) with PAA, thereby degrading organic pollutants in water. However, the conversion efficiency of Fe 3+ to Fe 2+ is low, which limits the activation efficiency of PAA. Fe / S-BC-750 introduces reducing sulfur substances to improve the conversion rate of Fe³⁺ to Fe²⁺, significantly enhancing the activation efficiency of PAA and promoting the generation of various reactive species (such as superoxide radicals (O 2 •- ), acetoxy radicals (CH 3 COO • ), and singlet oxygen ( 1 O 2 )). These reactive species can efficiently degrade organic pollutants in water while avoiding secondary pollution of metal catalysts. In addition, the magnetic Fe 3 O 4 loaded on the biochar effectively solves the problem of difficult recovery of biochar.

[0015] The preparation method of the present invention is simple to operate, has high synthesis efficiency, high activation PAA degradation performance, and good catalyst stability. Description of the Drawings

[0016] Figure 1a The kinetics of activating PAA to degrade SMX for the catalyst prepared in Example 1.

[0017] Figure 1b The kinetics of activating PAA to degrade SMX for the catalyst prepared in Example 2.

[0018] Figure 1c Curves of activating PAA to degrade SMX by Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3 respectively.

[0019] Figure 2a Curves of activating PAA to degrade SMX by Fe / S-BC-750 prepared in Example 1 under the influence of different catalyst dosages.

[0020] Figure 2b Curves of activating PAA to degrade SMX by Fe / S-BC-750 prepared in Example 1 under the influence of different PAA dosages.

[0021] Figure 3 SEM, TEM images of Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3 respectively, and elemental distribution map of Fe / S-BC-750.

[0022] Figure 4 Isotherm diagrams of Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3 respectively.

[0023] Figure 5 Tafel diagrams and electrochemical impedance spectroscopy diagrams of Fe / S-BC-750 and BC-750 prepared in Examples 1 and 3 respectively.

[0024] Figure 6 Curves of activating PAA to degrade SMX by Fe / S-BC-750 prepared in Example 1 under the influence of different pH values.

[0025] Figure 7 Bar charts of activating PAA to degrade SMX by Fe / S-BC-750 prepared in Example 1 under the influence of different anion concentrations and natural organic matter.

[0026] Figure 8 Recycling diagram of activating PAA to degrade SMX by Fe / S-BC-750 prepared in Example 1.

[0027] Figure 9Hysteresis loop of Fe / S-BC-750 prepared in Example 1. Detailed implementation mode

[0028] To further describe the present invention, a magnetic FeS for activating peracetic acid to degrade antibiotics provided by the present invention 2 / biochar material and its preparation method will be described in detail below. Example

[0029] The evenly ground Bischofia polycarpa powder (6.0 g) was mixed with 50 mL of FeSO 4 ·7H 2 O (0.5 mol / L) under a nitrogen atmosphere, stirred for 1 h, then transferred into a high-pressure reaction kettle, and hydrothermally treated at 180 °C for 24 h. After the reaction, the solid substance 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.

[0030] Put Fe / S-BC into a muffle furnace, with a heating rate of 10 °C / min, heated to 750 °C and held for 1 h.

[0031] After naturally cooling to room temperature, the sample in the crucible was transferred to a mortar and ground. The obtained solid product was named Fe / S-0.5-BC-750.

[0032] Keeping the heating rate and synthesis temperature of the sample in the muffle furnace unchanged, adjusting the molar concentration of ferrous sulfate heptahydrate to 0.10 mol / L, 0.25 mol / L, 0.75 mol / L, 1.00 mol / L, and the other steps were the same, and they were named Fe / S-0.10-BC-750, Fe / S-0.25-BC-750, Fe / S-0.75-BC-750, Fe / S-1.00-BC-750 respectively. Example

[0033] The evenly ground Bischofia polycarpa powder (6.0 g) was mixed with 50 mL of FeSO 4 ·7H 2 O (0.5 mol / L) under a nitrogen atmosphere, stirred for 1 h, then transferred into a high-pressure reaction kettle, and hydrothermally treated at 180 °C for 24 h. After the reaction, the solid substance 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] Put Fe / S-BC into a muffle furnace, with a heating rate of 10 °C / min, heated to 750 °C and held for 1 h.

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

[0036] 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 °C / min unchanged, the temperature of the muffle furnace was adjusted to 600 °C and 900 °C, and other steps were the same, named Fe / S-BC-600 and Fe / S-BC-900 respectively.

[0037] Figure 1a -b shows that the Fe / S-BC-750 catalyst prepared under the conditions of a molar concentration of FeSO 4 •7H 2 O of 0.5 mol / L, a heating rate of 10 °C / min, and heating to 750 °C and holding for 1 h has the highest degradation efficiency for the activation of PAA degradation of SMX. Example

[0038] The evenly ground Bischofia polycarpa powder (6.0 g) was mixed with 50 mL of ultrapure water, stirred for 1 h, then transferred to a high-pressure reactor and hydrothermally treated at 180 °C for 24 h. After the reaction, the solid matter was separated by filtration, washed several times with ultrapure water, and then dried and cooled at 80 °C to obtain a hydrothermal carbon precursor.

[0039] The above product was placed in a muffle furnace with a heating rate of 10 °C / min and heated to 750 °C for 1 h.

[0040] After natural cooling to room temperature, the sample in the crucible was transferred to a mortar and ground to obtain a solid product named BC-750.

[0041] According to Figure 1a -b The degradation effect of the catalyst on SMX shows that the preparation conditions of Fe / S-BC-750 are the most significant for the activation of PAA degradation of SMX when the molar concentration of ferrous sulfate heptahydrate is 0.5 mol / L and the temperature is 750 °C.

[0042] According to Figure 1c The degradation effect of the catalyst on SMX shows that compared with BC-750, the prepared Fe / S-BC-750 has a more significant effect on the activation of PAA degradation of SMX.

[0043] According to Figure 2aThe curves of Fe / S-BC-750 activating PAA to degrade SMX under the influence of different dosages of -b catalyst and different PAA concentrations. Considering the reaction cost and efficiency, compared with other reaction conditions, when the catalyst dosage is 0.2 g / L and the PAA addition concentration is 0.3 mM, activating PAA to degrade SMX is more green and efficient.

[0044] According to Figure 3 The results show that BC-750 exhibits an irregular layered structure with a porous surface conducive to organic adsorption, but Fe / S modification significantly enhances pore formation, indicating an improvement in mass transfer capacity. BC-750 shows a layered graphite structure with a lattice spacing of 0.248 nm, consistent with π-π stacked aromatic clusters. Fe / S-BC-750 exhibits clear lattice fringes of 0.159 nm (FeS 2 (031) crystal plane) and 0.253 nm (Fe 3 O 4 (311) crystal plane), confirming the coexistence of two crystal phases. The results of energy-dispersive spectroscopy elemental surface scanning analysis show that Fe, S, and O elements are uniformly distributed on the catalyst surface, verifying the uniform dispersion of FeS 2 and Fe 3 O 4 nanoparticles.

[0045] According to Figure 4 The BET results show that both Fe / S-BC-750 and BC-750 have large specific surface areas, which is conducive to exposing more active sites on the material surface, facilitating the adsorption of PAA and target pollutants on the material surface and the subsequent catalytic oxidation degradation process.

[0046] According to Figure 5 The analysis results show that the self-corrosion potential of Fe / S-BC-750 and BC-750 is -0.361 V, which decreases to -0.471 V after Fe / S modification, indicating that Fe / S-BC-750 has a greater electron transfer ability. In addition, the EIS of Fe / S-BC-750 has a smaller semicircle diameter and better charge separation. The above results show that the synergistic effect of Fe and S endows Fe / S-BC-750 with better electrochemical performance, which is conducive to better electron transfer.

[0047] According to Figure 6The results of the catalyst at different pH values showed that as the initial solution pH increased from 3.0 to 9.0, the removal rate of SMX was only slightly inhibited. Under acidic and neutral conditions, the change in the removal rate of SMX was small (about 4%). Even under alkaline conditions (pH = 9.0), the system could still maintain a high SMX removal rate (about 73%). The results indicated that the catalytic system exhibited excellent removal efficiency over a wide pH range and had strong anti-interference ability.

[0048] According to Figure 7 the results, low concentrations of Cl − and HA had a certain promoting effect on the removal of SMX. The addition of HCO 3 − and PO 4 3− both inhibited the removal of SMX. HCO 3 − competed with organic pollutants for HO • to generate CO 3 •– and inhibited the removal efficiency of organic pollutants in the activated PAA system.

[0049] According to Figure 8 the recycling results, Fe / S-BC-750 could still achieve 83% SMX removal after 4 recycling uses, showing good material stability.

[0050] According to Figure 9 the results of the hysteresis loop, Fe / S-BC-750 had sufficient ferromagnetism. Therefore, Fe / S-BC-75 was easy to recycle, avoiding secondary pollution to the environment.

[0051] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a magnetic FeS2 / biochar material for activating peracetic acid to degrade antibiotics, characterized in that: The steps include: (A) mixing a biochar raw material and an iron-sulfur source under a nitrogen atmosphere; (B) transferring the above obtained solution into a reaction vessel and heating it at a fixed temperature. After the reaction is completed, the solid phase is separated by filtration, washed with ultrapure water several times, dried and cooled, and then ground using a mortar; (C) The above solids were dispersed in a crucible and heated at a fixed temperature. After natural cooling, they were ground using a mortar to obtain magnetic FeS2 / biochar materials, which were labeled as Fe / S-BC-750. Wherein, the biochar raw material in step (A) is Chongyang wood powder, and the iron and sulfur source is ferrous sulfate heptahydrate (FeSO4·7H2O).

2. The preparation method according to claim 1, characterized in that: The molar concentration of FeSO4·7H2O is 0.5 mol / L.

3. The preparation method according to claim 1, characterized in that: Step (B) The fixed temperature was 180 °C and the hydrothermal time was 24 h.

4. The preparation method according to claim 1, characterized in that: In step (C), the fixed temperature is 750 °C and the heating time is 1 h.

5. The magnetic FeS2 / biochar material Fe / S-BC-750 with activated peracetic acid (PAA) is prepared according to the preparation method according to any one of claims 1 to 4.

6. The magnetic FeS2 / biochar material Fe / S-BC-750 according to claim 5 is used in the degradation of antibiotics by activated peracetic acid (PAA).

7. The use according to claim 6, characterized in that: Recovery of magnetic FeS2 / biochar material Fe / S-BC-750 by magnetic attraction.

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