Granular material with ferroferric carbide and zero-valent iron co-loaded on surface of silicon dioxide coated ferroferric oxide as well as preparation method and application of granular material
By co-loading iron carbide and zero-valent iron on silica coated on the surface of ferrous tetraoxide, the stability and removal efficiency problems in nitrite pollution treatment in high-salt environments are solved, and efficient and safe water purification is achieved Effect.
Patent Information
- Application Number
- CN202411442696.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2024-12-06
AI Technical Summary
The prior art is difficult to effectively reduce nitrite pollution in high-salt environments, zero-valent iron is prone to agglomeration in water bodies, the surface reduction reaction process is difficult to control, and the stability is poor.
Iron tetraoxide particles were prepared by hydrothermal method, and then silica coated with iron tetraoxide was prepared by hydrolysis reaction. Finally, iron carbide and zero-valent iron were loaded on silica coated with iron tetraoxide through reduction reaction. The surface is firmly combined with covalent action to improve the stability and activity of the material.
It improves the surface electrochemical activity and stability of the material, extends the service life, and achieves efficient removal of nitrite pollution in high saline water. The material is safe and non-toxic, and is suitable for magnetic separation and reuse.
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Figure CN119076065A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalytic materials and environmental protection, and in particular to a method for preparing a granular material in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide and an application thereof. The material can be applied in the field of environmental purification. Background Art
[0002] With the growth of population and economic development, the continuous progress of industry and agriculture, the pollution of the ocean has been increasing. Nitrite, as a water pollutant, will not only cause eutrophication of the water, but also endanger human health. In marine aquaculture, as the aquaculture progresses, a large amount of nitrite will accumulate in the water, which is not only not conducive to the aquaculture, but also pollutes the environment. However, due to the high-salt environment, the widespread use of microbial denitrification technology and ion resin adsorption technology cannot effectively reduce the nitrite content.
[0003] Zero-valent iron (ZVI) is particulate metallic iron (Fe(0)). ZVI is mainly composed of an Fe(0) core surrounded by an iron oxide or iron hydride shell. Its chemical reduction ability is: the Fe(0) core acts as an electron source, and the shell acts as an electron channel, releasing electrons quickly on the surface. These characteristics of zero-valent iron and its environmentally friendly nature make it an ideal agent for environmental purification.
[0004] Magnetic Fe 3 C not only has the advantages of abundant raw materials and low production cost, but also has a low Fermi level and high conductivity, and is mainly used in the field of electrocatalysis. 3 Although C has been widely studied in the field of electrocatalysis, it is rarely used in environmental water pollution treatment.
[0005] In recent years, encapsulating transition metals in carbon shells has been considered a promising technique for synthesizing highly active and stable functional catalysts, which not only prolongs their residence time but also promotes the catalytic reaction on the carbon surface due to the electron transfer of the encapsulated transition metals. Xiao Zhang, Zhongping Yao et al. realized the CNT, NCNT and Fe by using VASP and density functional theory (DFT) 3 The construction and optimization of C@NCNT geometry demonstrates that Fe 3 The addition of C can increase the charge density of the complex. Xiao Zhang, Jiankang Wang et al. designed a dual reaction center structure on the multi-channel of C-Fe and CS-Fe to promote the electron transfer process.
[0006] In view of the nitrite pollution in the high-salinity water environment, combined with the disadvantages of easy agglomeration of zero-valent iron, difficult to control the surface reduction reaction process, and poor stability, it is necessary to prepare a zero-valent iron-based material with low cost, stable and controllable structure. Summary of the invention
[0007] The object of the present invention is to provide a method for preparing a granular material in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide and its application. The preparation method of the material is to first prepare the iron oxide granular material by a hydrothermal method, then prepare the silicon dioxide-coated iron oxide by a hydrolysis reaction, and finally load the zero-valent iron and iron carbide on the surface of the silicon dioxide-coated iron oxide by a reduction reaction, so as to obtain a granular material in which iron carbide and zero-valent iron are co-loaded on the surface of the silicon dioxide-coated iron oxide. The reduction loading method used in the present invention firmly combines iron carbide and zero-valent iron on the surface of the silicon dioxide-coated iron oxide through covalent action, which greatly improves the stability of the material surface, improves the activity of the material, and prolongs the service life of the material. The granular material prepared by the present invention is safe and non-toxic, and is suitable for efficiently and stably treating nitrite pollution in high-salt water bodies.
[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0009] A method for preparing a granular material in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide, comprising the following steps:
[0010] S1, dissolving ferric chloride hexahydrate in ethylene glycol, stirring evenly, adding sodium citrate dihydrate and sodium acetate, stirring for 2-4 hours, transferring the liquid to a hydrothermal kettle for hydrothermal reaction, performing solid-liquid separation after the reaction, washing the solid product, and drying it in a drying oven for 10-15 hours to prepare ferrosoferric oxide particles;
[0011] S2, mixing ammonia water, anhydrous ethanol and water, adding the ferrosoferric oxide particles obtained in step S1 during ultrasound, and then ultrasound for 20-40 minutes, adding tetraethyl silicate after ultrasound, mechanically stirring for 5-7 hours, and then performing solid-liquid separation, washing the solid product, and drying it in a drying oven for 10-15 hours to obtain silicon dioxide-coated ferrosoferric oxide particles;
[0012] S3, adding carbon powder, ferric nitrate nonahydrate and the silica-coated ferroferric oxide particles obtained in step S2 into water, mechanically stirring for 6-8 hours, and then drying for 40-50 hours, and calcining the obtained solid in an inert atmosphere to obtain a granular material in which ferroferric carbide and zero-valent iron are co-loaded on the surface of the silica-coated ferroferric oxide.
[0013] Preferably, in step S1, the molar ratio of ferric chloride hexahydrate, ethylene glycol, sodium citrate dihydrate and sodium acetate is 1:(0.20-0.27):(0.15-0.20):(3.4-4.0).
[0014] Preferably, in step S1, the reaction temperature of the hydrothermal autoclave is 180°C-220°C, and the reaction time is 10-12 hours.
[0015] Preferably, in step S2, the concentration of the aqueous ammonia is 25wt.%-28wt.%.
[0016] Preferably, in step S2, the volume ratio of the aqueous ammonia, anhydrous ethanol and water is 1:(14-17):(3-6); the molar ratio of the ferrosoferric oxide to tetraethyl silicate is 1:(2.0-2.5).
[0017] Preferably, in step S3, the mass ratio of the carbon powder, ferric nitrate nonahydrate and silicon dioxide-coated ferrosoferric oxide particles is (1-4):(3-6):1.
[0018] Preferably, in step S3, the calcination temperature is 750° C.-900° C., and the calcination time is 2 hours; and the inert atmosphere is one or both of argon and nitrogen.
[0019] The granular material prepared by the above method in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide is applied to the removal of nitrite in a high-salt water environment, wherein the high-salt water environment refers to a water body with a NaCl content greater than or equal to 1wt.%.
[0020] Preferably, when the granular material in which the iron carbide and zero-valent iron are co-loaded on the surface of the silicon dioxide-coated iron oxide is used to remove nitrite contained in a high-salt water environment, the nitrite content should be 5ppm-50ppm, the amount of granular material added is 1-10g / L, and magnetic separation is used after application to achieve rapid recovery and reuse of the granular material.
[0021] The advantages of the present invention are:
[0022] 1. The present invention uses ferric chloride hexahydrate and ferric nitrate nonahydrate as iron sources, tetraethyl silicate as silicon source, and carbon powder as carbon source to synthesize the granular material in which the ferric carbide and zero-valent iron are co-loaded on the surface of the silicon dioxide-coated ferric oxide. The synthesis conditions are mild, the operation is simple, and the preparation is easy.
[0023] 2. The granular material prepared by the present invention, in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide, has C-Fe bonds, which promotes the rapid transfer of electrons, greatly improves the surface electrochemical activity of the material, and improves the removal efficiency of nitrite.
[0024] 3. Pure zero-valent iron is easy to oxidize and has magnetism, and can be easily used in water treatment magnetic separation technology. However, due to the accumulation of pollutants and non-magnetic iron oxides on the surface of the material during use, the zero-valent iron aggregates during use, reducing the removal efficiency. In the granular material of the present invention, in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide, the newly formed surface iron oxide also maintains good magnetism under the induction of the Fe-OC hyperconjugation effect during the reaction with nitrite. Therefore, its service life as a magnetic separation material can be greatly extended. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is an X-ray diffraction pattern of the granular material prepared in Example 1 in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide.
[0026] Figure 2 The X-ray photoelectron spectrum of the full spectrum peak and the C element 1s peak of the granular material prepared in Example 1 in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide; wherein: (a) the full spectrum peak; (b) the C element 1s peak.
[0027] Figure 3 The granular material prepared in Example 1, in which the iron carbide and zero-valent iron are co-loaded on the surface of the silicon dioxide-coated iron oxide, is applied to the removal of nitrite in a high-salt water body (NaCl content is 1 wt.%). At 298 K, the NO 2 - Content change curve. DETAILED DESCRIPTION
[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:
[0029] Example 1
[0030] In this embodiment, a granular material in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide is prepared. The specific process is as follows:
[0031] S1. Weigh ferric chloride hexahydrate, ethylene glycol, sodium citrate dihydrate, and sodium acetate in a molar ratio of 1:0.26:0.18:3.7, then dissolve ferric chloride hexahydrate in ethylene glycol, stir evenly, add sodium citrate dihydrate and sodium acetate, stir for 2 hours, transfer the liquid to a hydrothermal kettle for reaction, the reaction temperature is 200°C, the reaction time is 10 hours, then perform solid-liquid separation, wash the solid product, and dry it in a drying oven for 12 hours to prepare ferrosoferric oxide particles;
[0032] S2, the mass fraction of the ammonia water used is 25wt.%, and the ammonia water, anhydrous ethanol and water are weighed in a volume ratio of 1:16:4, and then the ferroferric oxide particles prepared in step S1 and tetraethyl silicate are weighed in a molar ratio of 1:2.3, and then the ammonia water, anhydrous ethanol and water are mixed, and the obtained ferroferric oxide is added in ultrasound, and then ultrasound is performed for 30 minutes. After ultrasound, tetraethyl silicate is added, mechanical stirring is performed for 6 hours, and then solid-liquid separation is performed, the solid product is washed, and dried in a drying oven for 12 hours to obtain a core-shell structure in which silicon dioxide is coated on the surface of the ferroferric oxide particles (silicon dioxide coated ferroferric oxide particles);
[0033] S3. Weigh carbon powder, ferric nitrate nonahydrate, and silica-coated ferroferric oxide particles in a mass ratio of 2:5:1, then add the carbon powder, ferric nitrate nonahydrate and the obtained silica-coated ferroferric oxide particles into water, mechanically stir for 7 hours, and then dry for 48 hours. The obtained solid is calcined at 800°C for 2 hours in a nitrogen atmosphere to obtain a granular material in which ferroferric carbide and zero-valent iron are co-loaded on the surface of the silica-coated ferroferric oxide.
[0034] Figure 1 The X-ray diffraction pattern of the granular material prepared in this example, in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide, shows that the corresponding Fe 3 O 4 , Fe 0 , Fe 3 The element peak of C indicates that the new sample was successfully synthesized. Figure 2 The X-ray photoelectron spectrum of the full spectrum peaks and the 1s peak of the C element of the granular material in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide prepared in this embodiment. It can be seen from the full spectrum that the prepared sample contains only four elements, C, O, Fe, and Si. It can be seen from the fine element spectrum that carbon exists in three forms, namely CC, CO, and OCO, which further indicates that the obtained sample is the expected granular material in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide.
[0035] Example 2
[0036] In this embodiment, the ferroferric carbide prepared in Example 1 and the zero-valent iron are co-loaded on the surface of the ferroferric oxide coated with silicon dioxide and applied to remove nitrite in a high-salt environment. The process is as follows:
[0037] 1. Mix 1g NaCl and 1mg NaNO 2 Add 100 ml of water into a three-necked flask and stir evenly to prepare a solution with a NaCl concentration of 1 wt.%, NaNO 2High saline water containing nitrite at a concentration of 10 ppm.
[0038] 2. Stir for 30 minutes under nitrogen atmosphere, add 1 g of the granular material obtained in Example 1 into a three-necked flask, stir mechanically to make it uniform, and then take a liquid sample every 30 minutes. The experimental time is 2 hours. Figure 3 The graph of the change of NO2- content in water at 298K when the granular material of iron carbide and zero-valent iron co-loaded on the surface of silicon dioxide-coated iron oxide was applied to the removal of nitrite in high-salt water (NaCl content of 1wt.%) is given. It can be seen from the figure that the granular material of iron carbide and zero-valent iron co-loaded on the surface of silicon dioxide-coated iron oxide has a significant effect on the removal of NO 2 - It has good removal performance, NO in water 2 - The content is below 1ppm and the removal rate is greater than 99%.
[0039] The present invention includes but is not limited to the above embodiments. Any equivalent replacement or partial improvement made under the principle of the spirit of the present invention shall be deemed to be within the protection scope of the present invention.
Claims
1. A method for preparing a granular material in which iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide, characterized in that: The method comprises the following steps: S1, dissolving ferric chloride hexahydrate in ethylene glycol, stirring evenly, adding sodium citrate dihydrate and sodium acetate, stirring for 2-4 hours, transferring the liquid to a hydrothermal kettle for hydrothermal reaction, performing solid-liquid separation after the reaction, washing the solid product, and drying it in a drying oven for 10-15 hours to prepare ferrosoferric oxide particles; S2, mixing ammonia water, anhydrous ethanol and water, adding the ferrosoferric oxide particles obtained in step S1 during ultrasound, and then ultrasound for 20-40 minutes, adding tetraethyl silicate after ultrasound, mechanically stirring for 5-7 hours, and then performing solid-liquid separation, washing the solid product, and drying it in a drying oven for 10-15 hours to obtain silicon dioxide-coated ferrosoferric oxide particles; S3, adding carbon powder, ferric nitrate nonahydrate and the silica-coated ferroferric oxide particles obtained in step S2 into water, mechanically stirring for 6-8 hours, and then drying for 40-50 hours, and calcining the obtained solid in an inert atmosphere to obtain a granular material in which ferroferric carbide and zero-valent iron are co-loaded on the surface of the silica-coated ferroferric oxide.
2. The preparation method according to claim 1, characterized in that: In step S1, the molar ratio of ferric chloride hexahydrate, ethylene glycol, sodium citrate dihydrate and sodium acetate is 1: (0.20-0.27): (0.15-0.20): (3.4-4.0).
3. The preparation method according to claim 1, characterized in that: In step S1, the hydrothermal reaction temperature is 180°C-220°C, and the reaction time is 10-12 hours.
4. The preparation method according to claim 1, characterized in that: In step S2, the concentration of the aqueous ammonia is 25wt.%-28wt.%.
5. The preparation method according to claim, characterized in that: In step S2, the volume ratio of the aqueous ammonia, anhydrous ethanol and water is 1:(14-17):(3-6); the molar ratio of the ferrosoferric oxide to tetraethyl silicate is 1:(2.0-2.5).
6. The preparation method according to claim 1, characterized in that: In step S3, the mass ratio of the carbon powder, ferric nitrate nonahydrate and silicon dioxide coated ferrosoferric oxide particles is (1-4): (3-6):
1.
7. The preparation method according to claim 1, characterized in that: In step S3, the calcination temperature is 750° C.-900° C., and the calcination time is 2 hours; the inert atmosphere is one or both of argon and nitrogen.
8. A granular material prepared by the method of any one of claims 1 to 7, wherein iron carbide and zero-valent iron are co-loaded on the surface of silicon dioxide-coated iron oxide.
9. The use of the granular material in which the iron carbide and zero-valent iron are co-loaded on the surface of the silicon dioxide-coated iron oxide according to claim 8, characterized in that: The granular material is used for removing nitrite in a high-salt water environment; the high-salt water environment refers to a water body in which the NaCl content is greater than or equal to 1wt.%.
10. The use according to claim 9, characterized in that: When the granular material is used to remove nitrite in a high-salt water environment, the nitrite content should be 5ppm-50ppm, and the amount added to the high-salt water environment is 1-10g / L. After application, magnetic separation is used to achieve rapid recovery of the granular material and reuse.