Zero-valent iron material with boric acid layer modified on surface, preparation method of zero-valent iron material and application of zero-valent iron material in antibiotic removal

Abstract

The invention relates to the technical field of aquaculture wastewater treatment, in particular to a surface boric acid layer modified zero-valent iron material and preparation and application thereof. The invention provides a preparation method of a surface boric acid layer modified zero-valent iron material, which comprises the following steps: mixing boric acid powder and zero-valent iron powder to obtain a mixture, adding water, and carrying out ball milling in an inert atmosphere to obtain surface boric acid layer modified zero-valent iron. According to the method, boric acid, water and zero-valent iron are subjected to mechanical ball milling modification on the basis of the mechanochemical principle by utilizing acting forces such as mechanical shearing force, impact force and friction force, and a uniformly coated surface boric acid layer is generated on the surface of the zero-valent iron material, so that the removal efficiency of florfenicol is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aquaculture wastewater treatment, and in particular to a zero-valent iron material modified with a surface boric acid layer, a preparation method thereof, and an application thereof in removing antibiotics. Background Art

[0002] Florfenicol (FF) is a broad-spectrum antibiotic in the chloramphenicol class of drugs, widely used in veterinary medicine to treat various infections caused by sensitive bacteria. In aquaculture, FF is also used to prevent and treat bacterial diseases in aquatic animals such as fish and shrimp. Consequently, FF is often found in aquaculture wastewater. FF undergoes a series of transformations in the environment and within organisms, with its main metabolites including deschloroflorfenicol (DFF) and dideschloroflorfenicol (DDFF).

[0003] In order to solve the environmental hazards caused by FF, selective dehalogenation (such as converting CX bonds into relatively harmless CH bonds) has become a key environmental remediation method. Among them, the reduction dehalogenation method can convert FF into non-toxic organic matter and halide ions through a reduction reaction. Common reduction dehalogenation methods include biological reduction, zero-valent metal (ZVM) reduction, electrochemical reduction and photocatalytic reduction. In particular, microscale zero-valent iron (mZVI) has become a research hotspot due to its low cost, easy availability and good environmental compatibility. In the mZVI system, the iron core (Fe 0 ) as the electron source, while the iron oxide shell (FeO x ) promotes the transfer of electrons and drives the dehalogenation reaction.

[0004] However, the inertness and hydrophilicity of the iron oxide shell restricts the efficient transfer of electrons from the iron core to the C—X bond, thereby limiting the efficiency of the dehalogenation reaction. Therefore, how to modify zero-valent iron materials to make them more suitable for FF processing is still a problem that is being explored. Summary of the Invention

[0005] The present invention provides a zero-valent iron material modified with a surface boric acid layer, a preparation method, and its application in antibiotic removal. Based on mechanochemical principles, this method utilizes mechanical shear, impact, and friction forces to mechanically ball-mill boric acid, water, and zero-valent iron. This creates a uniform boric acid layer on the surface of the zero-valent iron material, improving the removal efficiency of florfenicol.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a zero-valent iron material modified with a surface boric acid layer, comprising: mixing boric acid powder and zero-valent iron powder to obtain a mixture, adding water, and ball milling under an inert atmosphere to obtain the zero-valent iron material modified with a surface boric acid layer.

[0008] In the present invention, water, a grinding aid, is added to a mixture of boric acid powder and zero-valent iron powder. The boron and iron interact mechanochemically, forming a surface boric acid layer on the zero-valent iron surface, resulting in a surface boric acid-layer-modified zero-valent iron material. Experimental studies have demonstrated that the surface boric acid-layer-modified zero-valent iron material obtained by the method proposed in the present invention effectively enhances the zero-valent iron's ability to degrade florfenicol in water.

[0009] Preferably, the molar ratio between the boron in the boric acid powder and the iron in the zero-valent iron powder is 0.1 to 0.25:1.

[0010] Preferably, the mass volume ratio of the zero-valent iron powder to the water is 1 g:(50-125) μL.

[0011] Further preferably, the mass volume ratio of the zero-valent iron powder to the water is 1 g:(50-80) μL.

[0012] Further preferably, the mass-to-volume ratio of the zero-valent iron powder to the water is 1 g:(80-100) μL.

[0013] Further preferably, the mass volume ratio of the zero-valent iron powder to the water is 1 g:(100-120) μL.

[0014] Preferably, the mass volume ratio of the mixture to the water is 1 g: (60-100) μL.

[0015] Further preferably, the mass volume ratio of the mixture to the water is 1 g: (60-80) μL.

[0016] Further preferably, the mass volume ratio of the mixture to the water is 1 g: (80-100) μL.

[0017] Preferably, the water is oxygen-free water purged with inert gas.

[0018] Preferably, the zero-valent iron powder is elemental iron powder, reduced iron powder, cast iron powder, pig iron powder or industrial scrap iron containing zero-valent iron.

[0019] Preferably, the ball milling speed is 300-500 rpm, and the ball milling time is 2-30 h.

[0020] The present invention also provides a surface boric acid layer modified zero-valent iron material, wherein the surface boric acid layer modified zero-valent iron material comprises zero-valent iron and a surface boric acid layer uniformly wrapped on the surface of the zero-valent iron, wherein the thickness of the surface boric acid layer is 10 to 20 nm; based on the mass of the surface boric acid layer modified zero-valent iron material, the mass of the zero-valent iron is 60 to 90 wt%.

[0021] Preferably, the particle size of the surface boric acid layer modified zero-valent iron material is 1 to 10 μm.

[0022] The present invention also provides a surface boric acid layer-modified zero-valent iron material prepared by the above preparation method or the use of the surface boric acid layer-modified zero-valent iron material in repairing and removing florfenicol in aquaculture wastewater.

[0023] Preferably, the concentration of florfenicol is 10 to 100 ppm.

[0024] Therefore, the present invention has the following beneficial effects:

[0025] (1) The present invention utilizes boric acid as a boron modifier and water as a grinding aid to coat the boron element onto the surface of zero-valent iron particles under the action of mechanical force, thereby obtaining a zero-valent iron material having a surface boric acid layer.

[0026] (2) The surface boric acid layer modified zero-valent iron material synthesized by the method of the present invention has an excellent removal effect on florfenicol and can be used to solve the problem of regeneration treatment of aquaculture wastewater.

[0027] (3) The raw materials used in the method of the present invention are widely available, inexpensive, and used in low amounts. No wastewater or waste is generated during the preparation process, and the method is safe to use.

[0028] (4) The technical method of the present invention is simple, practical, has mild reaction conditions, is easy to operate, has high productivity, high repeatability, does not have excessively high requirements for equipment, can be used for large-scale experiments, and has significant economic, environmental and social effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a SEM-mapping comparison diagram of the zero-valent iron material prepared in the present invention;

[0030] Figure 2 This is an XRD comparison diagram of the zero-valent iron material prepared in the present invention;

[0031] Figure 3 This is a diagram showing the removal effect of FF in Example 1;

[0032] Figure 4 This is the FF removal effect diagram of Comparative Example 1;

[0033] Figure 5Comparison of the effects of different B / Fe molar ratios on the degradation of FF by zero-valent iron materials modified with a surface boric acid layer;

[0034] Figure 6 This is a comparison of the effects of different water addition amounts on the degradation of FF by zero-valent iron materials modified with a surface boric acid layer;

[0035] Figure 7 This is a diagram showing the removal effect of Example 1 for different FF concentrations;

[0036] Figure 8 This is a diagram showing the removal effect of FF in the river water system and aquaculture wastewater system of Example 1. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below generally represent only a portion of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0038] [Example]

[0039] Example 1

[0040] Reduced iron powder and boric acid were mixed, with the molar ratio of boron to iron controlled at 0.25 (denoted as B / Fe = 0.25). Water was then added and the mill was filled with inert gas. The combined mass ratio of reduced iron powder and boric acid to water was 1g:80μL, and the ratio of reduced iron powder to water was 1g:100μL. The milling was performed at 400 rpm for 20 hours to obtain zero-valent iron modified with a boric acid layer, designated B-ZVI. The zero-valent iron content in B-ZVI was 80wt%, the thickness of the boric acid layer was 10-20nm, and the particle size of the boric acid-modified zero-valent iron material was 6μm.

[0041] Example 2

[0042] This embodiment is substantially the same as embodiment 1, except that the molar ratio of boron to iron is 0.1, denoted as B / Fe=0.1.

[0043] Example 3

[0044] This embodiment is substantially the same as embodiment 1, except that the molar ratio of boron to iron is 0.2, denoted as B / Fe=0.2.

[0045] Example 4

[0046] This embodiment is substantially the same as embodiment 1, except that the molar ratio of boron to iron is 0.15, denoted as B / Fe=0.15.

[0047] Comparative Example 1

[0048] This comparative example is basically the same as Example 1, except that: the same total mass of reduced iron powder as that in Example 1 was ball-milled, and other parameters remained unchanged to obtain a zero-valent iron material; denoted as mZVI, where B / Fe=0.

[0049] Comparative Example 2

[0050] This comparative example is basically the same as Example 1, except that the mass ratio of reduced iron powder to boric acid and water is 1 g:28 μL.

[0051] Comparative Example 3

[0052] This comparative example is substantially the same as Example 1, except that the addition of water is omitted.

[0053] Comparative Example 4

[0054] This comparative example is substantially the same as Example 1, except that the molar ratio of boron to iron is 0.05, which is expressed as B / Fe=0.05.

[0055] Comparative Example 5

[0056] This comparative example is substantially the same as Example 1, except that the molar ratio of boron to iron is 0.3, which is expressed as B / Fe=0.3.

[0057]

Performance test

[0058] 1. SEM and XRD

[0059] The materials obtained in Example 1 and Comparative Example 1 were subjected to SEM and XRD tests, respectively. The results are as follows: Figures 1-2 As shown. Observe Figure 1 Numerous fine particles are evident on the surface of the B-ZVI material, likely representing the roughened boric acid layer formed after boron modification. Furthermore, the B-ZVI material's small particle size results in a larger surface area, providing more reactive sites for pollutant treatment and, in theory, higher degradation efficiency. In comparison, the surface morphology of mZVI, which is not modified with boric acid, is regular and smooth, and the particles are larger than those of the B-ZVI material. Comparing the SEM results of the two materials suggests that the incorporation of boron significantly alters the particle size of ZVI under mechanical forces. Figure 2 It can be clearly seen that the zero-valent iron material can be successfully synthesized according to the method provided by the present invention, and the three characteristic peaks of zero-valent iron corresponding to the (110), (200) and (211) crystal planes can be clearly found.

[0060] 2. Degradation results of different pollutants

[0061] The florfenicol degradation experiment was conducted as follows: the material was added to a bottle, followed by HEPEs buffer solution (50 mM, pH 7) and FF, resulting in a material concentration of 10 g / L and a contaminant concentration of 20 ppm. Samples were collected at designated time intervals, and the FF in the filtrate was analyzed using high-performance liquid chromatography.

[0062] The materials prepared in Examples 1 to 4 and Comparative Examples 1 to 5 were respectively subjected to the above-mentioned degradation test method to measure the corresponding degradation efficiency, and the results are as follows: Figures 3 to 6 shown.

[0063] Figure 3 is the B-ZVI material obtained in accordance with Example 1, Figure 4 This is the mZVI material obtained in Comparative Example 1. Figure 3 and Figure 4 The results show that there is a significant difference in the degradation effects of florfenicol between B-ZVI material and mZVI material, indicating that the degradation efficiency of FF by B-ZVI material is greatly improved under the action of the surface boric acid layer.

[0064] also, Figure 5 Figure 3 is the FF degradation efficiency diagram of the materials prepared under different boron-iron molar ratios. It can be observed that when the boron-iron molar ratio is 0.25, the degradation effect of B-ZVI material on florfenicol is the best.

[0065] Figure 6 The figure shows the FF degradation efficiency of the materials obtained under different water addition amounts. Previously, the applicant used silicate and zero-valent iron in water-assisted grinding to prepare silicon-doped zero-valent iron materials in patent CN 118724237A. In this patent, when the ratio of iron powder to water addition was 1g: (25-30) μL, it showed a treatment effect of nearly 100% of chlorine-containing organic pollutants; and when boric acid was used for modification, it was found that when the ratio between the mass of reduced iron powder and boric acid and water was 1g: 28 μL, its relative FF degradation effect was about 80%, showing a significant difference in water content with silicate. When the ratio between the mass of reduced iron powder and boric acid and water was 1g: 80 μL, it can be seen from Figure 6 It is clear that the degradation efficiency of B-ZVI for FF is close to 100%. This may be due to the special effect of the boric acid layer on the surface of B-ZVI material. More water is needed as a grinding aid to help activate the effectiveness of the surface boric acid layer, thereby achieving specific and efficient degradation of FF.

[0066] 3. Effect of Florfenicol Concentration on Degradation Efficiency

[0067] The degradation experiment of FF at concentrations of 10ppm, 20ppm, 50ppm and 100ppm was carried out using B-ZVI prepared in Example 1. The degradation experiment was completely consistent with that provided in the section "2. Degradation results of florfenicol". The results are recorded in Figure 7 Observation Figure 7 It was found that as the FF concentration increased, the corresponding degradation rate decreased; generally speaking, the increase in FF concentration did not significantly inhibit the degradation of B-ZVI, which means that the B-ZVI series materials provided by the present invention have wide applicability to the degradation of different concentrations of FF.

[0068] 4. Actual degradation effect of florfenicol

[0069] The B-ZVI prepared in Example 1 was used to conduct FF degradation experiments on river water in Huzhou, Zhejiang (the collection site was a river near the north side of Moganshan Campus of Zhejiang University of Technology) and aquaculture wastewater from a breeding factory in Xiazhuhu Street, Deqing County, Huzhou, Zhejiang.

[0070] The degradation experiment of florfenicol in river water is as follows: add the material to the bottle, then add river water and FF, so that the system concentration is maintained at 10g / L and the pollutant concentration is 20ppm. Other operations are the same as the degradation experiment.

[0071] The degradation experiment for florfenicol in aquaculture wastewater was as follows: Add the material to a bottle, then add aquaculture wastewater and FF to maintain the system concentration at 10g / L and the pollutant concentration at 20ppm. Other operations were the same as the degradation experiment.

[0072] Degradation results see Figure 8 It can be observed that under the action of B-ZVI, FF can still be degraded well in actual river water and aquaculture wastewater.

Claims

1. A method for preparing a zero-valent iron material modified with a surface boric acid layer, characterized in that: include: Boric acid powder and zero-valent iron powder are mixed to obtain a mixture, and then water is added and ball milled under an inert atmosphere to obtain a zero-valent iron material modified with a surface boric acid layer.

2. The preparation method according to claim 1, wherein The molar ratio of boron in the boric acid powder to iron in the zero-valent iron powder is 0.1 to 0.25:

1.

3. The preparation method according to claim 1, wherein The mass volume ratio of the zero-valent iron powder to the water is 1 g: (20-125) μL.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The mass volume ratio of the mixture to the water is 1 g: (60-100) μL.

5. The preparation method according to claim 1, wherein The zero-valent iron powder is elemental iron powder, reduced iron powder, cast iron powder, pig iron powder or industrial scrap iron containing zero-valent iron.

6. The preparation method according to claim 1, wherein The ball milling speed is 300-500 rpm, and the ball milling time is 2-30 hours.

7. The surface boric acid layer-modified zero-valent iron material prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The surface boric acid layer modified zero-valent iron material comprises zero-valent iron and a surface boric acid layer uniformly wrapped on the surface of the zero-valent iron, wherein the thickness of the surface boric acid layer is 10 to 20 nm; Calculated based on the mass of the surface boric acid layer modified zero-valent iron material, the mass of the zero-valent iron is 60-90 wt%.

8. The surface boric acid layer modified zero-valent iron material according to claim 7, characterized in that: The particle size of the surface boric acid layer modified zero-valent iron material is 1 to 10 μm.

9. Use of the surface boric acid layer-modified zero-valent iron material prepared by the preparation method according to any one of claims 1 to 6 or the surface boric acid layer-modified zero-valent iron material according to claim 7 or 8 in the repair and removal of florfenicol in aquaculture wastewater.

10. The use according to claim 9, characterized in that The concentration of the florfenicol is 10 to 100 ppm.

Images