Cellulose-based iron / molybdenum-carbon nanocomposite catalytic material, preparation method thereof and application thereof in degrading pollutants

Abstract

The present application relates to a cellulose-based iron / molybdenum-carbon nanocomposite catalytic material, a preparation method thereof and application thereof in degrading pollutants, the composite catalytic material is prepared by taking cellulose and ionic liquid as raw materials, making cellulose-based hydrogel, adsorbing ferrous sulfate and ammonium molybdate, drying, and synthesizing iron-carbon composite catalyst or iron / molybdenum-carbon-based composite catalyst through high-temperature carbonization, and can be used for activating persulfate to catalytically degrade antibiotic wastewater. The preparation method of the present application realizes the resource utilization of waste, successfully synthesizes a catalyst with high efficiency in activating persulfate, has good degradation effect, is used for activating persulfate to degrade antibiotic wastewater, has high activation performance, strong Fe 3+ / Fe 2+ cycle ability, effectively realizes the cycle between Fe 3+ and Fe 2+ in the iron-based catalyst-persulfate advanced oxidation process, has good treatment effect on antibiotic wastewater, and realizes effective utilization of natural resources.

Description

Technical Field

[0001] This invention relates to a cellulose-based iron / molybdenum-carbon nanocomposite catalytic material, its preparation method, and its application in degrading pollutants, belonging to the fields of chemistry and environmental technology. Background Technology

[0002] Agricultural waste such as straw is rich in cellulose. Cellulose, due to its high concentration of -OH groups, is an ideal material for synthesizing natural polymer hydrogels. However, the strong hydrogen bonds within cellulose make it difficult to dissolve in common solvents. Ionic liquids are green, low-toxicity, and environmentally friendly solvents with extremely high solubility for biomolecules like cellulose. Furthermore, ionic liquids can be recycled by displacing them in aqueous solutions, saving investment costs and effectively reducing secondary pollution. Cellulose-based hydrogels prepared by dissolving cellulose in ionic liquids, after high-temperature carbonization, form a three-dimensional network carbon skeleton that effectively disperses metal ions and promotes electron transfer in advanced oxidation processes.

[0003] Based on sulfate free radicals (SO4· - Advanced oxidation techniques (SR-AOPs) utilize activated persulfate (PS) to degrade organic pollutants in the environment. Compared to heterogeneous iron-based catalytic systems, iron-carbon-based heterogeneous catalytic materials have become a research hotspot due to their advantages such as high activation performance, wide applicability, and easy recovery. However, the Fe in the reaction... 3+ / Fe 2+ The poor recyclability between different phases is a key factor limiting the practical application of heterogeneous iron-based catalysts. The introduction of nitrogen species can improve the electron transport capacity of carbon-based materials, while molybdenum (Mo) can effectively achieve Fe ionization during the activation of PS by iron-based catalysts. 3+ / Fe 2+ cycle.

[0004] A search revealed no research reports on the one-step synthesis of cellulose-based iron / molybdenum-carbon composite catalysts using cellulose as a template for activating persulfate degradation of organic pollutants. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a cellulose-based iron / molybdenum-carbon nanocomposite catalytic material, its preparation method, and its application in degrading pollutants. Invention Overview:

[0007] The composite catalytic material of this invention is prepared in one step by dissolving cellulose in an ionic liquid to form a hydrogel, simultaneously adsorbing iron and molybdenum salts, followed by high-temperature calcination to produce a cellulose-based iron / molybdenum-carbon-based composite catalytic material. The iron and molybdenum sites are dispersed using a gel network via a template method, and the catalyst is synthesized in a one-step process under an anaerobic environment created by argon (Ar). The iron and molybdenum particles are uniformly dispersed in the pores of a nitrogen-doped porous carbon material. This material is used to activate the degradation of antibiotic-like wastewater by persulfate, exhibiting high activation performance and high Fe content. 3+ / Fe 2+ It has strong recycling capacity and effectively realizes the Fe process in the iron-based catalyst-persulfate advanced oxidation process. 3+ and Fe 2+ The cycle between these processes has a good treatment effect on antibiotic wastewater, realizing the effective utilization of natural resources. Invention Details:

[0009] This invention is achieved through the following technical solution:

[0010] A cellulose-based iron / molybdenum-carbon nanocomposite catalytic material, wherein the composite catalytic material comprises a three-dimensional porous carbon material, and iron clusters and molybdenum clusters are uniformly dispersed inside the porous carbon material.

[0011] The preparation method of the above-mentioned cellulose-based iron / molybdenum-carbon nanocomposite catalytic material includes the following steps:

[0012] 1) Preparation of cellulose;

[0013] 2) Cellulose powder is mixed with [BMIM]Cl ionic liquid, heated and stirred, and then replaced with deionized water to obtain cellulose-based hydrogel spheres;

[0014] 3) Mix FeSO4·7H2O solution and (NH4)6Mo7O 24 The mixture is prepared by mixing with 4H2O solution to obtain a mixed solution. Hydrogel balls are added to the mixed solution and the mixture is shaken in a constant temperature water bath until adsorption reaches saturation. The residual metal ions are removed, and the mixture is freeze-dried. The dried hydrogel balls are then calcined in an oxygen-free environment and ground into powder to obtain cellulose-based iron / molybdenum-carbon nanocomposite catalytic material.

[0015] According to a preferred embodiment of the present invention, the preparation of cellulose is specifically as follows: the collected wheat straw is washed clean, dried at 70°C, and then pulverized to collect powder smaller than 100 mesh, thus obtaining wheat straw powder. 8g of wheat straw powder is added to 400mL of 15% HNO3 and stirred at 110°C for 10h. After standing and settling, the supernatant is removed. Then, boiled deionized water is added and allowed to stand and settle to remove the supernatant. This operation is repeated until the mixture is milky white. The mixture is then stirred at room temperature for 12h. Finally, the milky white precipitate is filtered and collected. After freeze-drying, the pulverized powder is obtained, which is cellulose powder.

[0016] According to a preferred embodiment of the present invention, in step 2), the mass ratio of cellulose powder to [BMIM]Cl ionic liquid is (0.3-0.8):(6-15).

[0017] According to a preferred embodiment of the present invention, in step 2), the heating and stirring are performed by heating to 80-100°C and stirring for 3-6 hours.

[0018] According to a preferred embodiment of the present invention, in step 2), the deionized water replacement is performed by adding the mixture of cellulose powder and [BMIM]Cl ionic liquid dropwise to deionized water, and replacing the deionized water every 12 hours until the ionic liquid is completely replaced and recovered.

[0019] According to a preferred embodiment of the present invention, in step 3), the concentration of FeSO4·7H2O in the mixture is 0.1-0.5 mol / L.

[0020] Most preferably, in step 3), the concentration of FeSO4·7H2O in the mixture is 0.3 mol / L.

[0021] According to a preferred embodiment of the present invention, in step 3), the molar ratio of iron ions to molybdenum ions in the mixture is (1-5):1.

[0022] Most preferably, in step 3), the molar ratio of iron ions to molybdenum ions in the mixture is 2.5:1.

[0023] According to a preferred embodiment of the present invention, in step 3), the mass-to-volume ratio of the hydrogel spheres to the mixture is (3-6):(50-80), in g / mL.

[0024] According to a preferred embodiment of the present invention, in step 3), the heating process has a heating rate of 8-12℃ / min, a calcination temperature of 700-1000℃, a calcination time of 20-50min, and an argon flow rate of 300-500sccm.

[0025] The aforementioned cellulose-based iron / molybdenum-carbon nanocomposite catalytic materials are used for the efficient activation of persulfate to degrade organic pollutants.

[0026] The specific treatment steps are as follows: After mixing the cellulose-based iron-carbon composite catalyst or the cellulose-based iron / molybdenum-carbon composite catalyst with a solution containing antibiotics, persulfate is added to carry out the reaction. Under room temperature conditions, without adjusting the pH value of the solution, the organic pollutants in the reaction system are degraded.

[0027] More preferably, the mass-to-volume ratio of the catalyst to the organic pollutant solution is 0.003-0.015 g: 100 mL.

[0028] More preferably, the mass-to-volume ratio of persulfate to organic pollutant solution is 0.027-0.108 g: 100 mL.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. The cellulose used in this invention is an environmentally friendly material. The raw materials are readily available and inexpensive. The ionic liquid can be recycled and reused, which conforms to the principles of "resource utilization" and "renewability".

[0031] 2. This invention utilizes a template method to disperse and immobilize metallic Fe and Mo using a hydrogel network. In an oxygen-free environment created by Ar, a nitrogen-doped porous carbon material rich in metal sites is generated. The Fe active sites are uniformly dispersed within the porous carbon material, ensuring highly efficient catalytic performance. The uniformly dispersed Mo sites enhance the Fe activity during the reaction. 2+ / Fe 3+ cycle.

[0032] 3. The cellulose-based iron / molybdenum-carbon-based composite catalytic material prepared by this invention is suitable for treating antibiotic wastewater in a wide range of temperatures and complex environments containing various inorganic salts and natural organic matter. The catalyst is easy to recover, has broad application prospects, high environmental friendliness, and high catalytic efficiency. Attached Figure Description

[0033] Figure 1 This is a scanning electron microscope image of the cellulose-based iron / molybdenum-carbon composite catalytic material prepared in Example 1.

[0034] Figure 2 This is a transmission electron microscope (TEM) image of the cellulose-based iron / molybdenum-carbon composite catalytic material prepared in Example 1.

[0035] Figure 3 The image shows the energy dispersive spectrum of the cellulose-based iron / molybdenum-carbon composite catalytic material prepared in Example 1.

[0036] Figure 4 The image shows the XRD pattern of the cellulose-based iron / molybdenum-carbon composite catalyst prepared in Example 1.

[0037] Figure 5 This is a comparison chart showing the removal effect of cellulose-based iron-carbon composite catalyst on sulfadiazine in Experiment Example 1.

[0038] Figure 6 This is a comparison chart showing the removal effect of cellulose-based iron / molybdenum-carbon-based composite catalyst on sulfadiazine in Experiment Example 2.

[0039] Figure 7 The graph shows the degradation effect of different composite catalysts on sulfadiazine at different pH values ​​in Experiment Example 3.

[0040] Figure 8 The graph shows the degradation effect of different composite catalysts on sulfadiazine at different pH values ​​in Experiment Example 3.

[0041] Figure 9 The graph shows the degradation effect of different composite catalysts on sulfadiazine in Experiment Example 4 under the presence of different inorganic anions at 5 mmol / L.

[0042] Figure 10 The graph shows the degradation effect of different composite catalysts on sulfadiazine in Experiment Example 4 under the presence of different inorganic anions at 5 mmol / L.

[0043] Figure 11 The graph shows the degradation effect of different composite catalysts on bisphenol S in the presence of different concentrations of humic acid in Experiment Example 5.

[0044] Figure 12 The graph shows the degradation effect of different composite catalysts on bisphenol S in the presence of different concentrations of humic acid in Experiment Example 5. Detailed Implementation

[0045] The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings.

[0046] The raw materials used in the examples are all commercially available products.

[0047] Example 1

[0048] The preparation method of a highly efficient cellulose-based iron / molybdenum-carbon-based composite catalytic material for activating persulfate comprises the following steps:

[0049] (1) Dissolve 8g of wheat straw powder in 400mL of 15% HNO3, stir at 110℃ for 10h, let stand to precipitate, remove the supernatant, add boiled deionized water, let stand to precipitate, remove the supernatant, repeat this operation until the mixture is milky white, stir the mixture at room temperature for 12h, finally filter and collect the milky white precipitate, freeze dry and pulverize to obtain cellulose powder;

[0050] (2) Take 0.5g of the cellulose powder prepared in step (1) and mix it with 9.5g of [BMIM]Cl ionic liquid. Stir at 90℃ for 4h to obtain a cellulose 5wt% ionic liquid mixed solution. Add the mixed solution dropwise to deionized water with a syringe. Change the deionized water every 12h until the ionic liquid is completely replaced and recovered to obtain 5wt% cellulose-based hydrogel balls.

[0051] (3) Take 4g of the cellulose-based hydrogel spheres prepared in step (2) and immerse them in 60mL of 0.3mol / L FeSO4·7H2O solution. Shake the solution in a constant temperature water bath at 40℃ until saturation. Wash the surface of the hydrogel spheres with deionized water to remove residual metal ions and then freeze-dry them for later use.

[0052] (4) Take the dried gel balls treated in step (3) and place them in a tube furnace. Under the protection of argon atmosphere, heat them to 800°C at a heating rate of 10°C / min. After holding at this temperature for 30 minutes, cool them to room temperature, grind them into powder, and sieve them for later use. The resulting material is denoted as Fe@CNs.

[0053] (5) Take 4g of the cellulose-based hydrogel spheres prepared in step (2) and soak them in 60mL of FeSO4·7H2O and (NH4)6Mo7O 24 In a mixed solution of FeSO4·7H2O, the concentration of FeSO4·7H2O in the mixed solution is 0.3 mol / L, and the concentration of (NH4)6Mo7O is... 24 The concentration of ·4H2O was 0.12 mol / L. The hydrogel balls were adsorbed to saturation by shaking in a constant temperature water bath at 40℃. The residual metal ions on the surface of the hydrogel balls were washed with deionized water and then freeze-dried for later use.

[0054] (6) Place the dried gel balls treated in step (5) in a tube furnace and heat them to 800°C at a heating rate of 10°C / min under an argon atmosphere. After holding at this temperature for 30 minutes, cool them to room temperature, grind them into powder, and sieve them for later use to obtain a cellulose-based iron / molybdenum-carbon composite catalytic material, denoted as Fe. 2.5 Mo@CNs.

[0055] The scanning electron microscope image of the cellulose-based iron / molybdenum-carbon-based composite catalyst prepared in this embodiment is shown below. Figure 1 As shown, the transmission electron microscope image is as follows: Figure 2 As shown, the energy dispersive spectrum is as follows: Figure 3 As shown. Combined with Figures 1-3 It can be seen that iron and molybdenum particles are uniformly dispersed inside the nitrogen-doped porous carbon material, as shown in the XRD pattern. Figure 4 As shown.

[0056] Example 2

[0057] The preparation method of the cellulose-based iron-carbon-based composite catalytic material as described in Example 1 differs from that:

[0058] In step (3), the concentration of FeSO4·7H2O solution is 0.1 mol / L, and the rest of the operation and dosage are exactly the same as in Example 1.

[0059] Example 3

[0060] The preparation method of the cellulose-based iron-carbon-based composite catalytic material as described in Example 1 differs from that:

[0061] In step (3), the concentration of FeSO4·7H2O solution is 0.5mol / L, and the rest of the operation and dosage are exactly the same as in Example 1.

[0062] Example 4

[0063] The preparation method of the cellulose-based iron / molybdenum-carbon-based composite catalytic material as described in Example 1 differs from that:

[0064] In step (5), (NH4)6Mo7O 24 The concentration of the 4H2O solution was 0.03 mol / L, and the rest of the operation and dosage were exactly the same as in Example 1.

[0065] Example 5

[0066] The preparation method of the cellulose-based iron / molybdenum-carbon-based composite catalytic material as described in Example 1 differs from that:

[0067] In step (5), (NH4)6Mo7O 24 The concentration of the 4H2O solution was 0.06 mol / L, and the rest of the operation and dosage were exactly the same as in Example 1.

[0068] Example 6

[0069] The preparation method of the cellulose-based iron / molybdenum-carbon-based composite catalytic material as described in Example 1 differs from that:

[0070] In step (5), (NH4)6Mo7O 24 The concentration of the 4H2O solution was 0.3 mol / L, and the rest of the operation and dosage were exactly the same as in Example 1.

[0071] Comparative Example 1

[0072] The preparation method of cellulose-based iron-carbon composite catalytic materials includes the following steps:

[0073] (1) Dissolve 8g of wheat straw powder in 400mL of 15% HNO3, stir at 110℃ for 10h, let stand to precipitate, remove the supernatant, add boiled deionized water, let stand to precipitate, remove the supernatant, repeat this operation until the mixture is milky white, stir the mixture at room temperature for 12h, finally filter and collect the milky white precipitate, freeze dry and pulverize to obtain cellulose powder;

[0074] (2) Take 0.5g of the cellulose powder prepared in step (1) and mix it with 9.5g of [BMIM]Cl ionic liquid. Stir at 90℃ for 4h to obtain a cellulose 5wt% ionic liquid mixed solution. Add the mixed solution dropwise to deionized water with a syringe. Change the deionized water every 12h until the ionic liquid is completely replaced and recovered to obtain 5wt% cellulose-based hydrogel balls.

[0075] (3) Take 4g of the cellulose-based hydrogel spheres prepared in step (2) and immerse them in 60mL of 0.3mol / L FeSO4·7H2O solution. Shake the solution in a constant temperature water bath at 40℃ until saturation. Wash the surface of the hydrogel spheres with deionized water to remove residual metal ions and then freeze-dry them for later use.

[0076] (4) Take the dried gel balls treated in step (3) and place them in a tube furnace. Under the protection of argon atmosphere, heat them to 800°C at a heating rate of 10°C / min. After holding at this temperature for 30 minutes, cool them to room temperature, grind them into powder, and sieve them for later use. The resulting material is denoted as Fe@CNs.

[0077] Experimental Example

[0078] The following experiments demonstrate the effect of cellulose-based iron / molybdenum-carbon composite catalytic materials prepared under different conditions on the degradation of persulfate by sulfadiazine antibiotic solution.

[0079] Experimental Example 1

[0080] Experiments were conducted in Examples 1, 2, and 3 to activate the degradation of sulfadiazine antibiotic solution by persulfate using cellulose-based iron-carbon composite catalysts. 10 mg of Fe@CNs was prepared and placed in 100 mL of a 10 mg / L sulfadiazine solution. Catalytic degradation experiments were performed at room temperature without pH adjustment. The experimental results are as follows: Figure 5 As shown.

[0081] Experimental Example 2

[0082] Experiments were conducted in Examples 1, 4, 5, and 6 to activate persulfate degradation of sulfadiazine antibiotic solution using cellulose-based iron / molybdenum-carbon composite catalysts. 10 mg of Fe was used in the preparation... x Mo y @CNs were placed in 100 mL of a 10 mg / L sulfadiazine solution and subjected to catalytic degradation experiments at room temperature without pH adjustment. The experimental results are as follows: Figure 6 As shown.

[0083] Experimental Example 3

[0084] Experiments were conducted on Example 1 and Comparative Example 1 to demonstrate the activation of catalytic materials for the degradation of sulfadimidine antibiotic solution by persulfate under different pH conditions. 10 mg of the prepared catalyst was placed in 100 mL of a 10 mg / L sulfadimidine solution. The pH was adjusted to a range of 3-11 at room temperature for catalytic degradation experiments. The experimental results are as follows: Figure 7 , 8 As shown.

[0085] Experiment Example 4

[0086] Experiments were conducted on Example 1 and Comparative Example 1 to demonstrate the activation of catalytic materials for the degradation of sulfadiazine antibiotic solution by persulfate under different coexisting anion conditions. 10 mg of the prepared catalyst was placed in 100 mL of a 10 mg / L sulfadiazine solution. The reaction was carried out at room temperature without pH adjustment, with the anions being Cl... - SO4 2- HCO3 - and NO3 - The concentrations were all 5 mmol / L, and catalytic degradation experiments were conducted. The results are as follows: Figure 9 , 10 As shown.

[0087] Experimental Example 5

[0088] Experiments were conducted on Example 1 and Comparative Example 1 to demonstrate the activation of the catalytic material for the degradation of sulfadimidine antibiotic solution by persulfate under different coexisting organic compounds. 10 mg of the prepared catalyst was placed in 100 mL of a 10 mg / L sulfadimidine solution. Catalytic degradation experiments were performed at room temperature without pH adjustment, with the concentration of coexisting organic compound humic acid (HA) ranging from 2 mg / L to 10 mg / L. The experimental results are as follows. Figure 11 , 12 As shown.

[0089] Experimental Example 6

[0090] XRD pattern analysis was performed on Examples 1, 4, 5, and 6. The experimental results are as follows: Figure 4 As shown.

[0091] The results showed that the activation performance of the cellulose-based iron-carbon composite catalytic material first increased and then decreased with increasing iron content; the activation performance of the cellulose-based iron / molybdenum-carbon composite catalytic material first increased and then decreased with increasing molybdenum content; and the cellulose-based iron / molybdenum-carbon composite catalytic material had a wider pH adaptability range and stronger environmental adaptability than the cellulose-based iron-carbon composite catalytic material.

Claims

1. A cellulose-based iron / molybdenum-carbon nanocomposite catalytic material, wherein the composite catalytic material comprises a three-dimensional porous carbon material, wherein iron clusters and molybdenum clusters are uniformly dispersed inside the porous carbon material; The preparation method includes the following steps: 1) Preparation of cellulose; 2) Cellulose powder is mixed with [BMIM]Cl ionic liquid, heated and stirred, and then replaced with deionized water to obtain cellulose-based hydrogel spheres; 3) Mix FeSO4·7H2O solution and (NH4)6Mo7O24·4H2O to obtain a mixed solution. Add hydrogel balls to the mixed solution and shake in a constant temperature water bath until adsorption is saturated. Remove residual metal ions, freeze dry, and grind the dried hydrogel balls into powder after calcination in an oxygen-free environment to obtain cellulose-based iron / molybdenum-carbon nanocomposite catalytic material. The preparation method of the above-mentioned cellulose-based iron / molybdenum-carbon nanocomposite catalytic material includes the following steps: 1) Preparation of cellulose; 2) Cellulose powder and [BMIM]Cl ionic liquid are mixed, heated and stirred, and then replaced with deionized water to obtain cellulose-based hydrogel spheres; the mass ratio of cellulose powder to [BMIM]Cl ionic liquid is (0.3-0.8):(6-15), the heating and stirring are carried out at 80-100℃ for 3-6 hours, and the deionized water replacement is carried out by adding the mixture of cellulose powder and [BMIM]Cl ionic liquid dropwise to deionized water every 12 hours until the ionic liquid is completely replaced and recovered; 3) Mix FeSO4·7H2O solution and (NH4)6Mo7O24·4H2O solution to obtain a mixed solution. Add hydrogel balls to the mixed solution and shake in a constant temperature water bath until saturation. Remove residual metal ions, freeze dry, and grind the dried hydrogel balls into powder after calcination in an oxygen-free environment to obtain cellulose-based iron / molybdenum-carbon nanocomposite catalytic material. The concentration of FeSO4·7H2O in the mixed solution is 0.1-0.5 mol / L, the molar ratio of iron ions to molybdenum ions in the mixed solution is (1-5):1, the mass-volume ratio of hydrogel balls to the mixed solution is (3-6):(50-80), the unit is g / mL, the heating rate is 8-12℃ / min, the calcination temperature is 700-1000℃, the calcination time is 20-50min, and the argon flow rate is 300-500 sccm.

2. The cellulose-based iron / molybdenum-carbon nanocomposite catalytic material according to claim 1, characterized in that, The specific preparation of cellulose is as follows: After cleaning the collected wheat straw, dry it at 70℃ and then crush it. Screen out the powder with a mesh size of less than 100 and collect it for later use. Take 8g of wheat straw powder and add it to 400mL of 15% HNO3. Stir at 110℃ for 10h. After standing and settling, remove the supernatant. Then add boiled deionized water and let it stand and settling to remove the supernatant. Repeat this operation until the mixture is milky white. Then stir the mixture at room temperature for 12h. Finally, filter and collect the milky white precipitate. Freeze-dry and crush the precipitate to obtain the cellulose powder.

3. The application of the cellulose-based iron / molybdenum-carbon nanocomposite catalytic material according to claim 1, for the efficient activation of persulfate to degrade organic pollutants.

4. The application according to claim 3, characterized in that, The specific treatment steps are as follows: After mixing the cellulose-based iron-carbon composite catalyst or the cellulose-based iron / molybdenum-carbon composite catalyst with a solution containing antibiotics, persulfate is added to carry out the reaction. Under room temperature conditions, without adjusting the pH value of the solution, the organic pollutants in the reaction system are degraded. The mass-volume ratio of the catalyst to the organic pollutant solution is 0.003-0.015g:100mL; the mass-volume ratio of persulfate to the organic pollutant solution is 0.027-0.108g:100mL.

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