Formic acid modified nano zero-valent iron material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of environmental functional nano materials, and discloses a formic acid modified nano zero-valent iron material as well as a preparation method and application thereof. The preparation method comprises the following steps: adding formic acid into commercial nano zero-valent iron (nZVI), and carrying out ball milling by using a ball mill to obtain formic acid modified nano zero-valent iron. The preparation method disclosed by the invention is simple in process, and the obtained formic acid modified nano zero-valent iron has uniform particle size and very high Cr (III)-EDTA oxidative degradation and Cr (III) removal capabilities, is high in removal rate and removal rate, and can be widely applied to the field of environmental governance and remediation.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional nanomaterials technology, specifically relating to a formic acid-modified nanomaterial of zero valent iron, its preparation method and application. Background Technology

[0002] With economic development and expanding market demand, tailings and waste residues from the mining and smelting processes of construction sand, basalt, and kaolin enter the soil through atmospheric deposition from rainfall, resulting in the incorporation of ethylenediaminetetraacetic acid (EDTA). Chromium in the soil can react with EDTA to form stable Cr(III)-EDTA complexes. When chromium is released under changing soil conditions and exists in a water-soluble complex with EDTA, the solubility of heavy metal ions in the soil significantly increases, making chromium more prone to migration and thus increasing its mobility. This increased bioavailability of chromium also increases its risk of entering the food chain, leading to increased long-term ecological risks.

[0003] Because the complex formed by EDTA and trivalent chromium poses potential hazards to soil and the ecological environment, traditional treatment methods struggle to disrupt the structure of soils containing Cr(III)-EDTA. Furthermore, Cr(III)-EDTA exhibits resistance to biodegradation, making it difficult to degrade using conventional biological treatment technologies. Related research indicates that nano-zero-valent iron (nZVI) possesses the ability to oxidize organic matter and reduce and adsorb heavy metals, attracting widespread attention in the field of heavy metal pollution remediation. However, it still faces challenges such as the limited availability of active species, low reaction efficiency, and complex reaction processes.

[0004] Researchers have further improved the specific surface area, passivation resistance, treatment efficiency, and lifespan of nZVI by modifying it. CN119281404B discloses a zero-valent iron particle prepared by mixing micron-sized zero-valent iron, heteropolyacids, and noble metal compounds; however, this material suffers from drawbacks such as high cost, harsh reaction conditions, and high risk of secondary pollution, making it difficult to apply to the treatment of practical soil pollutants. CN120136284A discloses an application of oxalicized zero-valent iron in the treatment of organic pollutants, which improves the electron transfer efficiency of the material and thus enhances its ability to treat pollutants. However, the activation of reactive oxygen species requires peracetic acid, making the reaction process complex. Therefore, developing a green, environmentally friendly, cost-effective, and high-performance modified nano-zero-valent iron material is crucial. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing formic acid-modified nano-zero-valent iron materials. This method is green, simple, and can be scaled up industrially, producing materials with high dispersibility and stability.

[0006] Another object of the present invention is to provide a formic acid-modified nano-zero-valent iron material obtained by the above preparation method.

[0007] Another objective of this invention is to provide the application of the formic acid-modified nano-zero-valent iron material in environmental remediation, particularly in the oxidative degradation and removal of Cr(III)-EDTA pollutants in high geological background soils and other environmental systems contaminated by EDTA.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing formic acid-modified nano-zero-valent iron materials, comprising the following steps: Nano-sized zero-valent iron particles and formic acid were ball-milled and dried to obtain formic acid-modified nano-sized zero-valent iron materials.

[0009] Preferably, the nano-zero-valent iron is spherical.

[0010] Preferably, the nano-zero valent iron is 100-200 mesh.

[0011] Preferably, the mass ratio of the nano-zero-valent iron particles to formic acid is (12-67):1; more preferably, it is (12-31):1.

[0012] Preferably, the milling medium for the ball milling reaction is zirconia balls.

[0013] More preferably, the mass ratio of the nano-zero-valent iron particles to the zirconium oxide spheres is 1:(5-20), and even more preferably 1:7.5.

[0014] More preferably, the diameter of the zirconium oxide spheres is 1-6 mm.

[0015] Preferably, the ball milling reaction time is 1-6 hours, more preferably 4-6 hours.

[0016] Preferably, the ball milling reaction is carried out at a rotation speed of 300-500 rpm, and more preferably at 400-500 rpm.

[0017] Preferably, the ball milling direction is clockwise and counterclockwise, and the direction is changed every 30 minutes.

[0018] Preferably, the drying time is 30±5 min; the drying temperature is 60±5℃.

[0019] Secondly, the present invention provides a formic acid-modified nano-zero-valent iron material obtained by the above preparation method.

[0020] Thirdly, this invention provides the application of the formic acid-modified nano-zero-valent iron material in environmental remediation.

[0021] Preferably, the application is in the environmental remediation of EDTA pollution.

[0022] Preferably, the application is in the environmental remediation of co-polluted EDTA and heavy metals, specifically in the removal of EDTA and heavy metals from water and / or soil environments.

[0023] More preferably, the heavy metal is Cr(III).

[0024] This invention provides a formic acid-modified nano-zero-valent iron material prepared by the above-described method. The material surface has carboxyl groups, exhibiting high utilization of reactive oxygen species. It can efficiently oxidize and degrade organic matter and immobilize heavy metals by generating various active species, overcoming the technical bottlenecks of iron activity decay and ineffective oxidant decomposition in traditional Fenton-like systems. It also possesses advantages such as wide pH applicability and green economy. The scientific principle lies in the formation of Fe(HCOO)2 in zero-valent iron through mechanical ball milling, which improves the electron transfer efficiency of the material, enhances the utilization of reactive oxygen species, oxidizes and degrades organic pollutants, and immobilizes heavy metals on the material surface. Experimental verification shows that the material of this invention has high activity in treating Cr(Ⅲ)-EDTA in soil.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The particle size and surface morphology of the formic acid modified nano zero-valent iron material provided by the present invention can be controlled by controlling the preparation reaction conditions; (2) The formic acid modified nano-zero valent iron material of the present invention has a wide range of applications and applicable objects in the field of environmental remediation, for example: it is suitable for water heavy metal pollution or soil heavy metal pollution of different degrees; (3) The formic acid modified nano zero-valent iron material provided by the present invention has good biocompatibility and has the advantages of fast removal rate and high removal efficiency of heavy metals. (4) The preparation method provided by the present invention is simple and convenient to operate, and is easy to scale up and industrialize for production and application. No toxic reagents are used in the preparation process, and no toxic by-products are generated. Attached Figure Description

[0026] Figure 1 The image shows the infrared spectrum of the modified nano-zero-valent iron material of Example 1.

[0027] Figure 2 The image shows the XRD pattern of the modified nano-zero-valent iron material of Example 1.

[0028] Figure 3 The image shows the Fe 2p plot of the modified nano-zero-valent iron material in Example 1.

[0029] Figure 4 The images show SEM (left) and TEM (right) images of the modified nano-zero-valent iron material from Example 1.

[0030] Figure 5 This is a particle size distribution diagram of the modified nano-zero-valent iron material in Example 1.

[0031] Figure 6 This is a SEM image of the modified nano-zero-valent iron material from Example 6.

[0032] Figure 7 The curves showing the changes in Cr(III)-EDTA and Cr content over time for the modified nano-zero-valent iron material of Example 10 are shown.

[0033] Figure 8 The curves showing the change of Cr(III) and Cr(VI) content over time in the modified nano-zero valent iron material of Example 10 are shown.

[0034] Figure 9 The DMPO-•OH and DMPO-•O2 in the reaction process of the modified nano-zero valent iron material and Cr(III)-EDTA in Example 10 are examples of these compounds. - TEMP- 1 O2's EPR signal. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0036] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or conditions recommended by the manufacturer. All raw materials and reagents used, unless otherwise specified, are commercially available conventional products.

[0037] Example 1: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.27g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 400 rpm for 4 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0038] The material was characterized by analyzing the functional group composition of the formic acid-modified nano-zero-valent iron material using infrared spectroscopy (e.g., ...). Figure 1 As shown), at 1670, 1271 and 730cm −1At this location, characteristic peaks of C=O, C=C, and CO stretching vibrations appear, indicating the formation of Fe(HCOO)2 in the material. Combined with XRD test results (such as...), Figure 2 As shown in the figure, the diffraction peak at 2θ = 44.9° of the material highly matches that of the standard card, indicating that formic acid modification did not change the crystal structure of nZVI. XPS was used to analyze the Fe valence state distribution in the material (…). Figure 3 In FA-nZVI, zero-valent, divalent, and trivalent iron are all present, which is beneficial for electron transfer and the removal of contaminants. Its morphology and structure were observed using SEM and TEM (e.g., Figure 4 As shown, the material is spherical with uniform size and an average particle size of approximately 250 nm. The particle size was determined using a particle size analyzer. Figure 5 The results showed that the size of the reaction matched that of the SEM images. These results confirm at the molecular level that ball milling can achieve efficient modification of nZVI by formic acid molecules.

[0039] Example 2: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.06g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 400 rpm for 4 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0040] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, the Fe valence state distribution was analyzed by XPS, the morphology and structure were observed by SEM and TEM, and the particle size of the material was determined by a particle size analyzer. The results were similar to those in Example 1.

[0041] Example 3: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.13g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 400 rpm for 4 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0042] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, the Fe valence state distribution was analyzed by XPS, the morphology and structure were observed by SEM and TEM, and the particle size of the material was determined by a particle size analyzer. The results were similar to those in Example 1.

[0043] Example 4: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.2g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 400 rpm for 4 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0044] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, the Fe valence state distribution was analyzed by XPS, the morphology and structure were observed by SEM and TEM, and the particle size of the material was determined by a particle size analyzer. The results were similar to those in Example 1.

[0045] Example 5: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.33g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 400 rpm for 4 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0046] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, the Fe valence state distribution was analyzed by XPS, the morphology and structure were observed by SEM and TEM, and the particle size of the material was determined by a particle size analyzer. The results were similar to those in Example 1.

[0047] Example 6: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.27g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 300 rpm for 4 hours, with the milling direction being clockwise and counterclockwise, and the direction being changed every 30 minutes; 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0048] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, and the Fe valence state distribution was analyzed by XPS. The results were similar to those of Example 1. The morphology and structure were observed by SEM, and the particle size was approximately 400 nm.

[0049] Example 7: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.27g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 500 rpm for 4 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0050] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, and the Fe valence state distribution was analyzed by XPS. The results were similar to those of Example 1. The morphology and structure were observed by SEM, and the particle size of the material was approximately 100 nm.

[0051] Example 8: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.27g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 400 rpm for 5 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0052] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, and the Fe valence state distribution was analyzed by XPS. The results were similar to those of Example 1. The morphology and structure were observed by SEM, and the particle size was approximately 300 nm.

[0053] Example 9: Preparation of a formic acid-modified nanomaterial of zero valent iron 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.27g of formic acid. Add the mixture to a 250mL zirconia ball mill jar and add 50 6mm zirconia balls (30g in total) to the jar. 2) Use a planetary ball mill at 400 rpm for 6 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain FA-nZVI powder, dry it at 60℃ for 30 min, and store it for later use.

[0054] The functional group composition of the formic acid-modified nano-zero-valent iron material was analyzed by infrared spectroscopy, the phase composition was analyzed by XRD, and the Fe valence state distribution was analyzed by XPS. The results were similar to those of Example 1. The morphology and structure were observed by SEM, and the particle size of the material was approximately 100 nm.

[0055] Comparative Example 1 1) Weigh 4g of commercial nZVI powder (spherical, 100 mesh) and mix it with 0.27g of 2-pyridinecarboxylic acid and add it to a 250mL zirconia ball mill jar. Add 50 6 mm zirconia balls (30g in total) to the ball mill jar. 2) Use a planetary ball mill at 400 rpm for 4 hours. The grinding direction is clockwise and counterclockwise, and the direction is changed every 30 minutes. 3) Obtain 2-pyridinecarboxylic acid modified nZVI powder, dry it for 30 min, and store it for later use.

[0056] Compared to Example 1, this comparative example replaces formic acid with 2-pyridinecarboxylic acid.

[0057] Example 10: Cr(Ⅲ)-EDTA Removal Experiment 1) Prepare a 0.1 mmol / L Cr(III)-EDTA solution and adjust the pH to 6; 2) Take 0.4 g of FA-nZVI prepared in Examples 1-9 and add it to 100 mL of the solution obtained in step 1), and react in a shaker at 180 rpm for 6 h; take 0.4 g of 2-pyridinecarboxylic acid modified nZVI powder obtained in Comparative Example 1 and add it to 100 mL of the solution obtained in step 1), and react in a shaker at 180 rpm for 6 h; 3) Take samples at regular intervals, filter them, and then measure the concentrations of Cr(Ⅲ), Cr(Ⅵ), Cr(Ⅲ)-EDTA and the EPR signal in the solution; 4) The results showed that Examples 1-9 achieved a maximum Cr(III)-EDTA degradation rate and Cr(III) fixation rate of up to 80%. Figure 7 The lowest value was 63%, and the effect was better than the comparative example. Specific data are shown in Table 1. No Cr(VI) was generated during the reaction of Examples 1-9 with Cr(Ⅲ)-EDTA. Figure 8 •OH and •O2 were detected. - , 1 Signals of active substances such as O2 ( Figure 9 ).

[0058] Table 1 shows the degradation rate and Cr(III) fixation rate of different modified nano-zero valent iron materials Cr(III)-EDTA in Example 10.

[0059] Table 1

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing formic acid-modified nano-zero-valent iron materials, characterized in that, Includes the following steps: Nano-sized zero-valent iron particles and formic acid were ball-milled and dried to obtain formic acid-modified nano-sized zero-valent iron materials.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the nano-zero-valent iron particles to formic acid is (12-67):1; more preferably (12-31):

1.

3. The preparation method according to claim 1 or 2, characterized in that, The nano-zero-valent iron is spherical in shape; And / or, the nano-zero valent iron is 100-200 mesh.

4. The preparation method according to claim 1 or 2, characterized in that, The ball milling reaction time is 1-6 hours; preferably 4-6 hours.

5. The preparation method according to claim 1 or 2, characterized in that, The ball milling reaction is carried out at a rotation speed of 300-500 rpm; preferably 400-500 rpm. And / or, the ball milling direction is clockwise and counterclockwise, and the direction is changed every 30 minutes.

6. The preparation method according to claim 1 or 2, characterized in that, The ball milling media used in the ball milling reaction are zirconium oxide balls.

7. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of the nano-zero-valent iron particles to the zirconium oxide spheres is 1:(5-20); preferably 1:7.

5. And / or, the diameter of the zirconia spheres is 1-6 mm.

8. A formic acid-modified nano-zero-valent iron material obtained by the preparation method according to any one of claims 1-7.

9. The application of the formic acid-modified nano-zero-valent iron material as described in claim 8 in environmental remediation.

10. The application according to claim 9, characterized in that, Applications in the environmental remediation of EDTA pollution; And / or, its application in the environmental remediation of co-contaminated environments containing EDTA and heavy metals.

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