Iron-carbon nanocomposite and its preparation method and application

Abstract

The present invention provides an iron-carbon nanocomposite and a preparation method and application thereof. The preparation method comprises dissolving ferrous salt and aldose in an ethanol aqueous solution at a molar ratio of 1‑5:1‑10 to form a reactant solution, performing a hydrothermal reaction or a microwave heating reaction, and carbonizing to obtain the iron-carbon nanocomposite. The present invention also provides an iron-carbon nanocomposite obtained by the above preparation method. The present invention also provides the application of the above iron-carbon nanocomposite in treating halogenated hydrocarbon pollution. The preparation process of the iron-carbon nanocomposite provided by the present invention is simple, the raw materials used are cheap and easily available, and halogenated hydrocarbon organic pollutants such as carbon tetrachloride and trichloroethylene can be effectively removed from groundwater.

Description

Technical Field

[0001] The invention relates to the technical field of material synthesis, and relates to an iron-carbon nanocomposite and a preparation method and application thereof. Background Art

[0002] The pollutant composition in petrochemical wastewater is relatively complex. In addition to oil, sulfur, phenol, cyanide, and COD, the wastewater also contains many difficult-to-degrade organic pollutants, such as halogenated hydrocarbons (aliphatic hydrocarbons / aromatic hydrocarbons). Most halogenated hydrocarbons have a density greater than that of water, and a smaller surface tension and viscosity coefficient than water. When groundwater is seriously polluted, they will accumulate at the bottom of the aquifer, so halogenated hydrocarbons are also classified as non-aqueous phase heavy liquids. The treatment of halogenated hydrocarbons in groundwater has attracted widespread attention and attention.

[0003] At present, the carbon industry has also opened up new fields based on nanomaterials based on traditional carbon materials, such as carbon nanotubes, activated carbon, graphite-coated nanometal ions, etc. However, carbon materials such as activated carbon only play a role in concentrating and enriching pollutants in the process of pollutant treatment, and cannot effectively remove or degrade pollutants.

[0004] Nano-zero-valent iron (nZVI) has become a very active and popular technology in the fields of material synthesis, environmental remediation, and medicine due to its high reactivity. However, the agglomeration of unmodified zero-valent iron particles limits their wide application in various fields of the scientific community.

[0005] In order to improve the dispersibility and stability of nano-iron particles and effectively remove pollutants, current research uses methods such as adding dispersants and preparing coated nano-iron particles to improve the dispersibility and stability of nano-iron particles to effectively remove pollutants, but these two methods are relatively complex and difficult to implement. Therefore, a greener and more convenient method for producing iron-carbon composite materials is urgently needed to meet the needs of groundwater halogenated hydrocarbon remediation. Summary of the invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide an iron-carbon nanocomposite and a preparation method and application thereof. The iron-carbon nanocomposite has a good treatment effect when applied to the degradation treatment of halogenated hydrocarbon organic pollutants.

[0007] In order to achieve the above-mentioned purpose, the present invention provides a method for preparing an iron-carbon nanocomposite, which comprises dissolving ferrous salt and aldose in an ethanol aqueous solution at a molar ratio of 1-5:1-10 to form a reactant solution, performing a hydrothermal reaction or a microwave heating reaction, and carbonizing to obtain the iron-carbon nanocomposite.

[0008] In the above-mentioned preparation method, the adsorption of ferrous ions by carbon-supported materials (aldose) is utilized to make the carbon-supported materials become the nucleation center of mineralization (iron nanoparticles), followed by crystallization and growth, and the precursor of the composite of carbon-supported materials / iron-containing minerals is obtained, and carboxyl activated carbon / iron-containing nanomaterials can be obtained after high-temperature carbonization. The above-mentioned carboxyl activated carbon can be obtained by converting the carbon-supported materials, and the carboxyl activated carbon not only has an adsorption effect on halogenated hydrocarbon pollutants, but also can enhance the dispersibility and stability of nanoparticles. Compared with the physical and chemical methods for modifying nano iron particles, the preparation method of the iron-carbon nanocomposite provided by the present invention is more convenient and environmentally friendly.

[0009] In the above preparation method, preferably, the molar ratio of the ferrous salt to the aldose is 1-5:3-8.

[0010] In the above preparation method, preferably, the ferrous salt includes ferrous sulfate (FeSO4) and / or ferrous chloride (FeCl2). In a specific embodiment, a hydrate of a ferrous salt, such as FeSO4·7H2O, etc., can also be used.

[0011] In the above preparation method, aldose is selected as the carbon loading material, and carboxyl activated carbon can be generated through hydrothermal reaction and carbonization. Preferably, the aldose includes glucose.

[0012] In the above preparation method, preferably, in the reactant solution, the molar concentration of the ferrous salt is 0.1 mol / L-1 mol / L, and the molar concentration of the aldose is 0.25 mol / L-1 mol / L.

[0013] In the above preparation method, preferably, in the ethanol aqueous solution, the volume ratio of ethanol to water is 1:0.1-1:50, such as 1:1.

[0014] In the above preparation method, preferably, the temperature of the hydrothermal reaction is 150°C-230°C (eg, 180-200°C), and the time of the hydrothermal reaction is 5h-24h (eg, 5h-20h, 15h).

[0015] In the above preparation method, microwave heating is used for reaction, which has the advantages of being simple, rapid, efficient, and green compared to the traditional hydrothermal method. Preferably, the temperature of the microwave heating reaction is 280°C-350°C, the time of the microwave heating reaction is 0.5h-1h, and the microwave power can be controlled to be about 30KW.

[0016] In the above preparation method, preferably, the carbonization temperature is 600°C-750°C (eg 650°C-720°C), and the carbonization time is 5h-10h (eg 6h-8h).

[0017] According to a specific embodiment of the present invention, in the above preparation method, before carbonization, the preparation method further includes cooling, washing and drying the product of the hydrothermal reaction, and the product obtained after drying can be called a precursor of the iron-carbon nanocomposite. Specifically, the drying temperature is generally controlled to be 40°C-50°C, the drying time is generally controlled to be 180min-540min, and the washing can include centrifugal washing with ethanol.

[0018] The present invention also provides an iron-carbon nanocomposite obtained by the above preparation method. In a specific embodiment, the iron-carbon nanocomposite contains nano zero-valent iron. In some specific embodiments, the particle size of the nano zero-valent iron can be 20nm-60nm.

[0019] According to a specific embodiment of the present invention, the iron-carbon nanocomposite can be used to remove halogenated hydrocarbons. For example, the removal rate of carbon tetrachloride by the iron-carbon nanocomposite can reach 50%.

[0020] The present invention also provides the use of the iron-carbon nanocomposite in treating halogenated hydrocarbon pollution. In some specific embodiments, the mass ratio of the iron-carbon nanocomposite to halogenated hydrocarbon can be 25-100:4-16, for example 25:4. The removal rate of the iron-carbon nanocomposite for halogenated hydrocarbons such as carbon tetrachloride can reach more than 50%.

[0021] The beneficial effects of the present invention are:

[0022] 1. The present invention adopts ethanol solution to synthesize the iron-carbon nanocomposite rich in carboxyl groups, has a simple preparation process, uses cheap and readily available raw materials, has no special requirements for external environmental conditions, occupies little space, and has no secondary pollution.

[0023] 2. The iron-carbon nanocomposite provided by the present invention has both the adsorption effect of carbon materials and the strong reducing properties of nano zero-valent iron, which can avoid the agglomeration phenomenon caused by the high magnetism and van der Waals force between nano iron particles, and can effectively remove halogenated hydrocarbon organic pollutants such as carbon tetrachloride and trichloroethylene in groundwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the SEM image of the iron-carbon nanocomposite of Example 1.

[0025] Figure 2 This is the XRD pattern of the iron-carbon nanocomposite of Example 1.

[0026] Figure 3 This is the infrared spectrum of the iron-carbon nanocomposite of Example 1.

[0027] Figure 4These are the experimental results of the degradation of carbon tetrachloride by commercial zero-valent iron powder (Figure a) and commercial activated carbon materials (Figure b).

[0028] Figure 5 The results of the experiment on the degradation of carbon tetrachloride by the iron-carbon nanocomposite of Example 1 are shown. DETAILED DESCRIPTION

[0029] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0030] Example 1

[0031] 1. Dissolve 8.60 g of FeSO4·7H2O and 16.78 g of glucose in a 100 mL ethanol-water solution (ethanol: water volume ratio 1:1) beaker and stir until completely dissolved to form a reactant solution;

[0032] 2. Take 80 mL of the reactant solution and place it in a 100 mL polytetrafluoroethylene sleeve. Use a microwave heating device with a microwave power of 30 KW. After 10 minutes, heat the sleeve to 350°C and keep it for 1 hour. Then cool the reaction product at room temperature, wash it with anhydrous ethanol by centrifugation, retain the precipitate, and dry it in a vacuum drying oven at 50°C for 6 hours to obtain an iron-carbon composite precursor.

[0033] 3. The iron-carbon composite precursor is placed in a tube furnace, nitrogen is introduced into the tube furnace, and carbonized at 680° C. for 6 h, and then cooled to room temperature to obtain an iron-carbon nanocomposite.

[0034] Figure 1 The SEM image of the product prepared in this example, Figure 2 This is the XRD pattern of the iron-carbon nanocomposite. Figure 1 The white circles in the middle are zero-valent iron nanoparticles. Figure 1 It can be seen that the nano-sized zero-valent iron in the product is attached to the carbon nanomaterial, and there is no agglomeration between the nanoparticles, and the dispersion is good. The nano-zero-valent iron is evenly distributed on the surface of the porous nano-activated carbon, and the iron nanoparticle size is 20nm-60nm. Figure 2 It can be seen that the XRD results show that the peaks at 44.5°, 65°, and 85° in 2θ are mainly characteristic peaks of zero-valent iron, which indicates that there is a lot of zero-valent iron in the composite nanomaterial.

[0035] The pH value of the aqueous solution of the iron-carbon nanocomposite of Example 1 (mass concentration of 8.6 wt%) was tested and the result was 6.1. The iron-carbon nanocomposite was tested by infrared spectroscopy. The test results are as follows: Figure 3 As shown in Table 1, the peak positions related to the carboxyl group are shown. Figure 3 It can be seen that the material is at 1690cm -1 The nearby absorption peak is the carboxyl stretching vibration peak (the absorption position of C=O in the form of CH2-CH-COOH di-association is shifted to a low wave number due to the influence of hydrogen bonding), which proves that the material contains carboxyl groups.

[0036] Table 1

[0037]

[0038] Test Example 1

[0039] This test example provides a carbon tetrachloride degradation performance test using the iron-carbon nanocomposite prepared in Example 1, commercial zero-valent iron powder (manufactured by Nangong Dinghong Metal Materials Co., Ltd., model JR-Fe-T01), and commercial activated carbon (manufactured by Changzhou Zhiguang Activated Carbon Co., Ltd., model 8-16 mesh coconut shell activated carbon) as the test samples. The test process is as follows:

[0040] 1. Add 0.1g of the sample to be tested to 100mL of carbon tetrachloride (16mg / L) solution and place it in a shaker (25 degrees, 125r / min) for degradation experiments. Set up at least 3 parallel controls for each group of samples to be tested. Take carbon tetrachloride as a single pollutant, sample every 30min, for a total of 5 times, and the reaction time lasts for 150min. Use gas chromatography to investigate the degradation effect of the iron-carbon nanocomposite.

[0041] Figure 4 The results of the degradation experiment of carbon tetrachloride by commercial zero-valent iron powder (Figure a) and commercial activated carbon material (Figure b) are shown in Figure 1. Figure 5 The degradation test results of the iron-carbon nanocomposite of Example 1 on carbon tetrachloride are shown in FIG. Figure 4 , Figure 5 The chromatographic results are integrated to obtain the peak area and then the carbon tetrachloride removal rate. Figure 4 , Figure 5 It can be seen that when the reaction time reaches 150 minutes, the removal rates of carbon tetrachloride in the solution treated with commercial zero-valent iron powder and commercial activated carbon are only 12% and 30%. However, the removal rate of carbon tetrachloride by the iron-carbon nanocomposite prepared by the present invention reaches 50%, which is significantly higher than the above two commercial materials. This shows that the iron-carbon nanocomposite provided by the present invention has excellent pollutant adsorption and degradation effects and can be applied to the degradation of halogenated hydrocarbons.

Claims

1. A method for preparing an iron-carbon nanocomposite, comprising dissolving a ferrous salt and an aldose in an ethanol aqueous solution at a molar ratio of 1-5:1-10 to form a reactant solution, and subjecting the solution to microwave heating reaction and carbonization to obtain the iron-carbon nanocomposite; The temperature of the microwave heating reaction is 280°C-350°C, and the time of the microwave heating reaction is 0.5h-1h; The carbon nanocomposite material contains nano zero-valent iron and porous nano activated carbon, wherein the nano zero-valent iron is distributed on the surface of the porous nano activated carbon, and the particle size of the nano zero-valent iron is 20 nm-60 nm; The ferrous salt includes ferrous sulfate and / or ferrous chloride.

2. The preparation method according to claim 1, wherein The molar ratio of the ferrous salt to the aldose is 1-5:3-8.

3. The preparation method according to claim 1, wherein The aldose includes glucose.

4. The preparation method according to claim 1, wherein In the reactant solution, the molar concentration of the ferrous salt is 0.1 mol / L-1 mol / L, and the molar concentration of the aldose is 0.25 mol / L-1 mol / L.

5. The preparation method according to claim 1, wherein In the ethanol aqueous solution, the volume ratio of the ethanol to water is 1:0.1-1:

50.

6. The preparation method according to claim 1, wherein In the ethanol aqueous solution, the volume ratio of the ethanol to water is 1:

1.

7. The preparation method according to claim 1, wherein The carbonization temperature is 600° C.-750° C., and the carbonization time is 5 h-10 h.

8. The preparation method according to claim 1, wherein The carbonization temperature is 650° C.-720° C., and the carbonization time is 6 h-8 h.

9. The preparation method according to any one of claims 1 to 8, wherein: Before carbonization, the preparation method further comprises cooling, washing and drying the product of the microwave reaction.

10. The preparation method according to claim 9, wherein: The drying temperature is 40° C.-50° C., the drying time is 180 min-540 min, and the washing includes centrifugal washing with ethanol.

11. An iron-carbon nanocomposite obtained by the preparation method according to any one of claims 1 to 10.

12. Use of the iron-carbon nanocomposite according to claim 11 in treating halogenated hydrocarbon pollution.

13. The use according to claim 12, wherein: The mass ratio of the iron-carbon nanocomposite to the halogenated hydrocarbon is 25-100:4-16.

14. The use according to claim 13, wherein: The mass ratio of the iron-carbon nanocomposite to the halogenated hydrocarbon is 25:4.

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