Preparation method of nano zero-valent iron cluster particles and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LONGYAN UNIV
- Filing Date
- 2024-06-07
- Publication Date
- 2026-07-21
Smart Images
Figure CN118598326B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental protection materials technology, and in particular relates to a method for preparing nano-zero-valent iron cluster particles and their application. Background Technology
[0002] Since its development, nano-zero-valent iron (nZVI) has been widely used in groundwater and soil remediation due to its high activity and wide range of applications. However, its high preparation cost, difficulty in maintaining activity, and tendency to agglomerate limit its further application. Researchers have used various dispersants to disperse nano-zero-valent iron, such as carboxymethyl cellulose, sodium dodecylbenzene sulfonate, and sophorolipids. However, these methods all rely on the reduction of nano-zero-valent iron with sodium borohydride, which solves the problems of agglomeration and oxidation. However, the high preparation cost of nano-zero-valent iron remains a challenge. Carbothermic reduction, which uses carbon reduction at high temperatures to prepare zero-valent iron, offers a solution to this problem. Studies have shown that zero-valent iron can be obtained by pyrolyzing iron salts with biomass powder at temperatures above 900°C for several hours. This is because the pyrolysis of carbon at high temperatures produces reducing gases such as CO, which reduce iron to its zero-valent state. Changes in the valence state of iron species are accompanied by changes in morphology. Typically, the zero-valent iron (ZVFe) prepared is already agglomerated, with particle sizes generally larger than 100 nm, and its activity is significantly lower compared to nano-sized ZVFe. To reduce the particle size of ZVFe, ball milling is used. However, ball milling removes the protective layer of ZVFe, making it difficult to maintain the activity of the prepared nano-sized ZVFe. Therefore, how to ensure that ZVFe prepared in carbothermal reduction does not agglomerate, does not lose activity, and is easily stored is one of the problems that currently needs to be solved in the carbothermal reduction method. Summary of the Invention
[0003] The purpose of this invention is to reduce the production cost of nano-zero valent iron, reduce the agglomeration effect of nano-zero valent iron to control the size of nano-zero valent iron clusters below 70 nm, solve the fatal defect of easy oxidation when stored in air, and develop a method for effectively activating and removing metronidazole by synthesizing clustered nano-zero valent iron particles through carbothermal reduction. Therefore, a method for preparing nano-zero valent iron cluster particles and its application are proposed.
[0004] To achieve the above objectives, the present invention provides the following technical solution:
[0005] A method for preparing nano-zero-valent iron cluster particles includes the following steps: mixing iron salt, plant waste powder, iron complexing agent and solvent and then carrying out a carbothermic reduction reaction to obtain the nano-zero-valent iron cluster particles; the iron complexing agent includes at least one of gallic acid, pyromellitic acid and terephthalic acid.
[0006] Furthermore, the iron salt is selected from at least one of ferric nitrate, ferric chloride, and ferric carbonate.
[0007] Furthermore, the plant waste powder is at least one of sugarcane bagasse, straw, rice husk, coconut shell, sawdust, and bamboo shavings, and its cellulose content must be higher than 60%.
[0008] Furthermore, the mass ratio of the iron salt to the plant waste powder is (1-7):1; the molar ratio of the iron salt to the iron complexing agent is 1:(0.5-2).
[0009] Furthermore, the solvent is water or ethanol.
[0010] Furthermore, the mixing is carried out at 60°C for 0.5-12 hours.
[0011] Furthermore, the conditions for the carbothermic reduction reaction are: heating to 800-1000℃ at a heating rate of 1-5℃ / min under a nitrogen atmosphere, and pyrolysis for 30-180min.
[0012] The present invention also provides nano-zero valent iron cluster particles prepared by the above preparation method, with a diameter <70nm and a nano-zero valent iron content greater than 60wt%.
[0013] This invention also provides an application of nano-zero-valent iron cluster particles in the treatment of organic matter and heavy metals in wastewater. The organic matter is an antibiotic, specifically selected from at least one of metronidazole, monobromodiphenyl ether, metronidazole, florfenicol, norfloxacin, tetracycline, and oxytetracycline; the heavy metal is specifically selected from at least one of lead (Pb), cadmium (Cd), and copper (Cu).
[0014] This invention utilizes nano-zero-valent iron clusters prepared by carbothermal reduction. In solutions containing antibiotics, the addition of a certain amount of persulfate facilitates the degradation of antibiotics through advanced oxidation processes involving both free and non-free radicals. The reactive oxygen species are primarily generated by the reaction between the nano-zero-valent iron and the persulfate. Furthermore, in soils containing heavy metal ions, the addition of these nano-zero-valent iron clusters, prepared by carbothermal reduction, removes the heavy metal ions through the reducing properties and co-precipitation of the zero-valent iron.
[0015] Compared with the prior art, the present invention has the following advantages and technical effects:
[0016] 1) This invention provides nano-zero-valent iron cluster particles. Due to the addition of iron complexing agent, the agglomeration of zero-valent iron during carbothermal reduction is overcome, so that the particle size of nano-zero-valent iron cluster particles is controlled below 70nm.
[0017] 2) This invention utilizes a carbothermal reduction method to prepare nano-zero-valent iron clusters, effectively increasing the nano-zero-valent iron content and reducing costs. The preparation method meets the requirements of large-scale, low-cost industrial production, with simple reaction conditions, easy operation, and convenient industrialization. The prepared material contains more than 60 wt% nano-zero-valent iron.
[0018] 3) The nano-zero-valent iron cluster particles of this invention exhibit strong reactivity and overcome the technical shortcomings of traditional zero-valent iron, such as easy aggregation, instability, difficulty in transportation, and difficulty in storage. They can be applied to environmental remediation. The remediation process is simple, requiring no other complex equipment or processes, and can be directly used in small-scale wastewater treatment plants for the removal of pollutants such as antibiotics and heavy metals. They can also be used for soil remediation, groundwater remediation, etc., showing great development potential. They can also be used in other chemical reactions that use zero-valent iron as a catalyst. Attached Figure Description
[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0020] Figure 1 The image shows the XRD pattern of the nano-zero-valent iron cluster particles prepared in Example 1 of this invention.
[0021] Figure 2 The image shows the XRD pattern of the zero-valent iron cluster particles prepared in Comparative Example 1 of this invention.
[0022] Figure 3 This is a graph showing the content of nano-zero valent iron in the nano-zero valent iron cluster particles prepared in Example 1 of the present invention;
[0023] Figure 4 This is a TEM image of a single particle in the nano-zero-valent iron cluster particles prepared in Example 1 of the present invention;
[0024] Figure 5 This is a TEM image of the nano-zero-valent iron cluster particles prepared in Example 1 of the present invention;
[0025] Figure 6 This is a TEM image of the labeled nano-zero-valent iron cluster particles prepared in Example 1 of the present invention;
[0026] Figure 7 The diagram shows the effect of different materials activating persulfate to remove antibiotics according to the present invention.
[0027] Figure 8 This is an analytical diagram of the intermediate product of the activation of persulfate to remove metronidazole by nano-zero-valent iron cluster particles prepared in Example 1 of the present invention;
[0028] Figure 9The efficiency of the nano-zero-valent iron cluster particles prepared in Example 2 of this invention in stabilizing the heavy metal lead in soil;
[0029] Figure 10 The efficiency of the nano-zero-valent iron cluster particles prepared in Example 3 of this invention in stabilizing heavy metal copper in soil;
[0030] Figure 11 This invention demonstrates the efficiency of the nano-zero-valent iron cluster particles prepared in Example 4 of this invention in stabilizing the heavy metal cadmium in soil. Detailed Implementation
[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0036] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.
[0037] All raw materials used in this invention were purchased from the market.
[0038] This invention utilizes a metal complexing agent to disperse iron ions, significantly reducing the particle size of zero-valent iron during carbothermal reduction. The amount of metal complexing agent can be controlled to regulate the particle size of nano-zero-valent iron. More complexing agent results in higher iron ion dispersion and smaller nano-zero-valent iron clusters; less complexing agent results in lower iron ion dispersion and larger nano-zero-valent iron clusters. Furthermore, the carbothermal reduction method significantly reduces the production cost of nano-zero-valent iron.
[0039] The preparation method of the nano-zero-valent iron cluster particles of the present invention includes the following steps: mixing iron salt, plant waste powder, iron complexing agent and solvent and then carrying out a carbothermic reduction reaction to obtain the nano-zero-valent iron cluster particles; the iron complexing agent includes at least one of gallic acid, pyromellitic acid and terephthalic acid, preferably gallic acid.
[0040] In the following preferred embodiments of the present invention, the iron salt is selected from at least one of ferric nitrate, ferric chloride and ferric carbonate, preferably ferric nitrate.
[0041] In the following preferred embodiments of the present invention, the plant waste powder is at least one selected from sugarcane bagasse, straw, rice husk, coconut shell, sawdust, and bamboo shavings, preferably sugarcane bagasse. The dry weight cellulose content of the plant waste powder is higher than 60 wt%.
[0042] In the following preferred embodiments of the present invention, the mass ratio of the iron salt to the plant waste powder is (1-7):1, preferably 3.6:1; the molar ratio of the iron salt to the iron complexing agent is 1:(0.5-2), preferably 1:(0.8-1.2), and more preferably 1:1. The particle size of the prepared nano-zero valent iron can be flexibly adjusted according to the amount of metal complexing agent.
[0043] In the following preferred embodiments of the present invention, the solvent is water or anhydrous ethanol. The mixing is carried out at 60°C for 0.5-12 hours, preferably 2 hours.
[0044] In the following preferred embodiments of the present invention, the conditions for the carbothermic reduction reaction are as follows: under a nitrogen atmosphere, heating to 800-1000℃ (preferably 900℃) at a heating rate of 1-5℃ / min (preferably 5℃ / min), pyrolysis for 30-180min (preferably 180min), and then naturally cooling to room temperature.
[0045] Using the above preparation method, nano-zero-valent iron cluster particles can be prepared. The diameter of the nano-zero-valent iron cluster particles is <70nm, and the content of nano-zero-valent iron is greater than 60wt%.
[0046] The nano-sized zero-valent iron cluster particles can be used to degrade organic matter in wastewater. The organic matter is an antibiotic, specifically selected from at least one of metronidazole, monobromodiphenyl ether, florfenicol, norfloxacin, tetracycline, and oxytetracycline. Taking metronidazole as an example, a metal chelating agent is added to a mixed solution of iron salt and plant waste powder, and the solution is pyrolyzed in a tube furnace at 900°C. The iron ions in the complexed state are reduced to zero-valent iron. Due to the complexation effect, the obtained zero-valent iron avoids large-scale agglomeration, reducing the particle size of the carbothermic reduced zero-valent iron. Adding nano-sized zero-valent iron cluster particles and oxidants such as persulfate to the metronidazole solution can achieve degradation of the target substance through advanced oxidation.
[0047] The method for treating antibiotic-contaminated wastewater specifically includes the following steps: adding the above-mentioned nano-zero-valent iron cluster particles and the oxidant persulfate to the polluted water body and mixing them for in-situ remediation. The persulfate is selected from at least one of sodium persulfate, sodium persulfate, and sodium sulfite, with sodium persulfate being preferred.
[0048] When the concentration of antibiotics in the polluted water is 1-100 mg / L (preferably 10 mg / L), the dosage of the nano-zero-valent iron cluster particles is 0.01-0.5 g / L (preferably 0.02 g / L), and the dosage of the oxidant persulfate is 1-5 mM (preferably 1 mM). The remediation time is 1-100 min.
[0049] The technical solution of the present invention will be further illustrated by the following embodiments.
[0050] Example 1 - Preparation of nano-zero-valent iron cluster particles
[0051] 1) Place 4.04g of ferric nitrate (0.01mol), 1.12g of sugarcane bagasse that has passed through a 60-mesh sieve, and 1.70g of gallic acid (0.01mol) into a beaker containing 50mL of ethanol, stir at 60℃ for 2h, and dry for later use;
[0052] 2) The dried sample was transferred to a corundum boat and placed in a tube furnace under a nitrogen atmosphere. It was heated to 900℃ for 180 min at a heating rate of 5℃ / min to obtain nano-zero valent iron cluster particles, denoted as BAGAFe.
[0053] Comparative Example 1 - Preparation of Zero-Valence Iron Cluster Particles
[0054] Same as Example 1, except that gallic acid was not added, and the resulting zero-valent iron cluster particles were denoted as BAFe.
[0055] Comparative Example 2 - Preparation of Nano-Zero-Variant Iron (nZVI) by Liquid Phase Reduction
[0056] Weigh 2g of FeSO4 and add it to 100mL of ethanol-water solution (ethanol to water volume ratio 3:7, the same below). Stir well on a magnetic stirrer. Then weigh 1.08g of sodium borohydride and add it to 50mL of ethanol-water solution. Slowly add this sodium borohydride solution dropwise into ferrous sulfate solution. Place the solution on a magnet to precipitate for 5 minutes. Wash three times each with deionized water, ethanol, and acetone. Dry in a glove box for 12 hours. The prepared material is denoted as nZVI.
[0057] Comparative Example 3 - Preparation of Aging Liquid-Phase Reduced Nanoscale Zero-Variant Iron (O2 / nZVI)
[0058] Similar to Comparative Example 2, the difference is that nZVI was aged in an aerobic transition chamber for 12 hours, denoted as O2 / nZVI.
[0059] Figure 1 The image shows the XRD pattern of the zero-valent iron nanoparticles prepared by carbothermic reduction after adding gallic acid in Example 1. As shown in the figure, the crystallization peak of gallic acid completely disappeared after pyrolysis, indicating that the gallic acid-iron complex is decomposed after high-temperature pyrolysis, leaving only zero-valent iron. A clear zero-valent iron crystallization peak was also observed in the prepared material, showing no difference compared to the zero-valent iron standard PDF card (#06-0696). This indicates that the addition of gallic acid does not affect the formation of zero-valent iron in the material.
[0060] Figure 2 The XRD pattern of the micro / nano BAFe composite material prepared by carbothermal reduction without gallic acid in Comparative Example 1 is shown in the figure. As can be seen, zero-valent iron can also be prepared by the ordinary carbothermal reduction method. However, the iron content of the product prepared by this method is lower than that of the nano-zero-valent iron clusters prepared with gallic acid. Relevant data can be found in [link to relevant data]. Figure 3 .from Figure 3 As can be seen, the nano-zero-valent iron cluster particles prepared by adding gallic acid in Example 1 contain 62.1% nano-zero-valent iron, while the nano-zero-valent iron cluster particles prepared by not adding gallic acid in Comparative Example 1 contain only 17.2% nano-zero-valent iron.
[0061] The nano-zero-valent iron clusters prepared by carbothermic reduction of gallic acid in Example 1 were examined by transmission electron microscopy (TEM). The results are as follows: Figure 4-6 As shown. Figure 4 As shown, the particle size of a single nano-zero-valent iron cluster is approximately 20-30 nm. Figure 5 As shown, nano-sized zero-valent iron clusters are dispersed within the carbon material, spaced a certain distance apart. Figure 6 As shown, for some Figure 5Measurements were taken of the medium-sized particles, and the results showed that the average particle size was 24.0 nm, the largest particle size was 69.4 nm, and the smallest particle size was 9.59 nm. These results indicate that the particle size of the zero-valent iron clusters prepared under the condition of a 1:1 molar ratio of iron to gallic acid is less than 70 nm.
[0062] Application Example 1
[0063] The specific steps of the experiments on the removal of antibiotics by nano-zero-valent iron cluster particles and nano-zero-valent iron-activated persulfate are as follows:
[0064] 0.02 g / L of materials (BAGAFe nano-zero-valent iron cluster particles prepared in Example 1, BAFe ordinary carbothermal reduced zero-valent iron prepared in Comparative Example 1, nZVI nano-zero-valent iron prepared in Comparative Example 2, and oxidized nZVI nano-zero-valent iron prepared in Comparative Example 3) were added to a solution containing 10 mg / L metronidazole contamination. Then, 1 mM sodium persulfate (PDS) was added as an oxidant to the reaction system. The reaction was carried out at room temperature and pH 7.0. The nZVI nano-zero-valent iron group needed to be stored in an atmosphere chamber for the reaction. Samples were taken at various time points, and the metronidazole concentration was analyzed by high-performance liquid chromatography. The results are as follows: Figure 7 .
[0065] from Figure 7 It can be seen that nano-zero-valent iron cluster particles and nano-zero-valent iron-activated persulfate have similar metronidazole removal efficiencies. This indicates that nano-zero-valent iron cluster particles prepared by carbothermal reduction have the same reactivity as nZVI, and that nano-zero-valent iron cluster particles are easier to store, reducing preparation and transportation costs. However, the activation efficiency of oxidized O2 / nZVI for sodium persulfate and its metronidazole removal efficiency are significantly lower than those of nZVI stored in the atmosphere chamber. This indicates that nZVI is easily oxidized and loses its activity.
[0066] Metronidazole (MNZ) degradation intermediates such as Figure 8 As shown, the degradation pathway is as follows Figure 8 During the degradation of MNZ, the degradation reaction mainly occurs through five mechanisms: cyano hydrolysis, C-OH oxidation, demethylation, dehydroxylation, and deamination.
[0067] Example 2
[0068] Same as Example 1, except that the molar ratio of ferric nitrate to gallic acid is 1:2, and nano-zero valent iron cluster particles are prepared, denoted as BAGAFe.
[0069] The nano-zero-valent iron clusters prepared using this embodiment have an average particle size of 25.2 nm and a nano-zero-valent iron content of 60.5%.
[0070] 0.16 g of BAGAFe prepared in Example 2 and 0.16 g of BAFe prepared in Comparative Example 1 were added to a serum bottle containing 2.0 g of lead-contaminated soil with a concentration of 1786.5 mg / kg. The solution was placed in a shaker with a rotation speed of 250 r / min. The concentration of lead in the soil was determined by acid extraction and atomic absorption spectrophotometry. The results are as follows: Figure 9 BAFe stabilized 44.5% of lead in the soil within one week, while BAGAFe stabilized 96.3% of lead in the soil.
[0071] Example 3
[0072] Same as Example 1, except that gallic acid was replaced with pyromellitic acid in equal molar amounts to obtain nano-zero valent iron cluster particles, denoted as BATAFe.
[0073] The nano-zero-valent iron clusters prepared using this embodiment have an average particle size of 45.6 nm and a nano-zero-valent iron content of 57%.
[0074] 0.16 g of BATAFe prepared in Example 3 and 0.16 g of BAFe prepared in Comparative Example 1 were added to a serum bottle containing 2.0 g of copper-contaminated soil with a concentration of 2536.75 mg / kg. The solution was placed in a shaker with a rotation speed of 250 r / min. The concentration of lead in the soil was determined by acid extraction and atomic absorption spectrophotometry. The results are as follows: Figure 10 BAFe stabilized 39.6% of the heavy metal copper in the soil within one week, while BATAFe stabilized 94.6% of the heavy metal copper in the soil.
[0075] Example 4
[0076] Same as Example 1, except that gallic acid was replaced with terephthalic acid in equal molar amounts to obtain nano-zero valent iron cluster particles, denoted as BAPTAFe.
[0077] The nano-zero-valent iron clusters prepared using this embodiment have an average particle size of 53.2 nm and a nano-zero-valent iron content of 53%.
[0078] 0.16 g of BAPTAFe (prepared in Example 4) and 0.16 g of BAFe (prepared in Comparative Example 1) were added to a serum bottle containing 2.0 g of cadmium-contaminated soil with a concentration of 52.94 mg / kg. The solution was placed in a shaker at a speed of 250 r / min. The concentration of lead in the soil was determined by acid extraction and atomic absorption spectrophotometry. The results are as follows: Figure 11 BAFe stabilized 27.8% of the heavy metal cadmium in the soil within one week, while BAPTAFe stabilized 84.3% of the heavy metal cadmium in the soil.
[0079] Comparative Example 4
[0080] Same as Example 1, except that the molar ratio of ferric nitrate to gallic acid is 1:0.1.
[0081] The zero-valent iron clusters prepared using this embodiment have an average particle size of 100.8 nm and a nano-zero-valent iron content of 22%, achieving a 79% removal rate of metronidazole within 30 min.
[0082] Comparative Example 5
[0083] Same as Example 1, except that gallic acid is replaced with carboxymethyl cellulose in an equal molar amount.
[0084] The zero-valent iron clusters prepared using this embodiment have an average particle size of 168.2 nm and a nano-zero-valent iron content of 0%, achieving a removal rate of 26% for metronidazole within 30 min.
[0085] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for preparing nano-zero-valent iron cluster particles, characterized in that, Includes the following steps: The nano-zero-valent iron cluster particles are prepared by mixing iron salts, plant waste powder, iron complexing agent and solvent and then carrying out a carbothermic reduction reaction; the iron complexing agent is gallic acid. The molar ratio of the iron salt to the iron complexing agent is 1:(0.5-2). The diameter of the nano-zero-valent iron cluster particles is <70nm, and the content of nano-zero-valent iron is greater than 60wt%.
2. The method for preparing nano-zero-valent iron cluster particles according to claim 1, characterized in that, The iron salt is selected from at least one of ferric nitrate, ferric chloride, and ferric carbonate.
3. The method for preparing nano-zero-valent iron cluster particles according to claim 1, characterized in that, The plant waste powder is at least one of sugarcane bagasse, straw, rice husk, coconut shell, sawdust, and bamboo shavings.
4. The method for preparing nano-zero-valent iron cluster particles according to any one of claims 1-3, characterized in that, The mass ratio of the iron salt to the plant waste powder is (1-7):
1.
5. The method for preparing nano-zero-valent iron cluster particles according to claim 1, characterized in that, The solvent is water or ethanol.
6. The method for preparing nano-zero-valent iron cluster particles according to claim 1, characterized in that, The mixing is carried out at 60°C for 0.5-12 hours; the conditions for the carbothermic reduction reaction are: under a nitrogen atmosphere, heating to 800-1000°C at a heating rate of 1-5°C / min, and pyrolysis for 30-180 minutes.
7. A nano-sized zero-valent iron cluster particle, characterized in that, It is prepared using the preparation method according to any one of claims 1-6.
8. The application of the nano-zero-valent iron cluster particles as described in claim 7 in the treatment of organic matter in wastewater.
9. The application according to claim 8, characterized in that, The organic compound is an antibiotic.