Preparation method and application of iron-based MOF nano composite material for kitchen waste degradation

Abstract

The invention provides a preparation method and application of an iron-based MOF (Metal Organic Framework) nano composite material for kitchen waste degradation, and the preparation method specifically comprises the following steps: taking ferric trichloride as a metal source, taking N, N-dimethylformamide (DMF) as a solvent, matching with 2-methylimidazole as an organic ligand, and carrying out solvothermal reaction to generate the iron-based MOF nano composite material. The material has a high specific surface area, a porous structure and excellent catalytic activity, and the organic matter degradation efficiency of kitchen waste can be remarkably improved. Through catalytic reaction under mild conditions, the material can rapidly generate active oxygen species, and organic matter degradation is effectively catalyzed. The nano composite material prepared by the invention has excellent catalytic performance and thermal stability, can be recycled for multiple times, has the characteristics of lower cost, no toxicity and environment friendliness, and is suitable for being applied to the industrial process of kitchen waste treatment on a large scale.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste treatment and resource utilization, and particularly relates to a preparation method of an iron-based MOF nanocomposite for degradation of kitchen waste and application thereof. BACKGROUND

[0002] With the acceleration of urbanization, kitchen waste treatment has become an important issue in environmental protection and resource utilization. Kitchen waste is mainly composed of organic matter. Traditional treatment methods such as composting and anaerobic fermentation have problems such as long treatment cycle, low efficiency, large treatment facility area, etc., and are difficult to meet the demand of large-scale treatment. In recent years, the application of catalytic materials in waste treatment has attracted widespread attention, especially metal-organic framework materials (MOF) with high specific surface area, adjustable pore structure and multifunctional active sites, which have shown good application prospects in the degradation of organic waste.

[0003] Iron-based MOF (Fe-MOF) is considered as a potential catalytic material due to its rich iron ion active center and low synthesis cost. By further compounding carbon-based materials, the conductivity and stability of Fe-MOF can be significantly improved, thereby enhancing its catalytic efficiency in the degradation process of kitchen waste. The present application aims to provide a preparation method of an efficient and low-cost iron-based MOF nanocomposite to solve the problem of low efficiency in current kitchen waste treatment. SUMMARY

[0004] In view of the above problems in kitchen waste treatment, the present application provides a preparation method of an iron-based MOF nanocomposite for degradation of kitchen waste. Through a simple and environmentally friendly process route, a Fe-MOF nanocomposite with excellent catalytic activity and adsorption performance is prepared. The composite material exhibits excellent organic matter removal effect in the degradation process of kitchen waste, and can shorten the treatment time and reduce the energy consumption.

[0005] To achieve the above-mentioned purposes, the present application adopts the following technical solutions: The application provides a preparation method of an iron-based MOF nanocomposite for kitchen waste degradation, and specifically comprises the following steps: taking iron trichloride as a metal source, using N,N-dimethylformamide (DMF) as a solvent, mixing and performing magnetic stirring for 10-15 minutes until complete dissolution, so as to form a transparent iron ion solution; taking 2-methylimidazole as an organic ligand, dissolving in DMF, stirring until complete dissolution, so as to form a transparent ligand solution; slowly adding the iron ion solution into the ligand solution, stirring while adding, stirring for 10-15 minutes, ensuring uniform mixing, and then continuing to stir for 30-50 minutes to ensure sufficient uniformity of the precursor solution; transferring the uniformly mixed precursor solution into a 100 mL high-pressure reaction kettle, sealing, and then placing into a constant-temperature oven at 100-120 DEG C to perform a solvothermal reaction for 24-36 hours; after the reaction is completed, naturally cooling the reaction kettle to room temperature, taking out the reaction liquid, and using a centrifuge to centrifuge the reaction liquid at a speed of 5000 rpm for 10 minutes to separate out a solid product; sequentially washing the obtained solid with anhydrous ethanol and deionized water alternately for 3 times, stirring for 5 minutes each time to remove residual organic matter and unreacted precursors; placing the washed solid sample in a vacuum drying box at 60 DEG C to dry for 12 hours until the sample is completely dried, and finally obtaining the iron-based MOF nanocomposite.

[0006] Further, in the preparation method of the iron-based MOF nanocomposite, the dosages of the components are specifically as follows: 5-20 parts by mass of iron trichloride, 5-12 parts by mass of DMF, and 3-10 parts by mass of 2-methylimidazole, and the volume ratio of the iron ion solution to the ligand solution is 1:1-1:10.

[0007] The application further provides application of the iron-based MOF nanocomposite obtained by the above preparation method in degradation of kitchen waste.

[0008] The degradation process comprises the following steps: after the Fe-MOF nanocomposite and the kitchen waste are fully mixed, stirring is performed at 80-100 r / min, the reaction temperature is controlled to be 25 DEG C-35 DEG C, the reaction pH is controlled to be 5-8, and after 12 h-24 h of reaction, the degradation is completed.

[0009] Further, the specific dosages are as follows: the mass ratio of the Fe-MOF nanocomposite to the kitchen waste is 1:5-1:10.

[0010] Further, after the kitchen waste is degraded, the weight loss rate of the kitchen waste is 60%-80%, and the soluble COD accounts for 20%-50%.

[0011] The application provides a preparation method of an iron-based MOF nanocomposite for kitchen waste degradation, and compared with existing strengthening methods, the following obvious advantages are obtained: 1、The iron-based MOF nanocomposite material of the present application has high specific surface area and porous structure, can quickly generate active oxygen species (such as •OH free radicals), effectively catalyze the degradation of complex organic matter in kitchen waste, significantly improve the COD removal rate, and the highest can reach more than 80%, the degradation efficiency is much higher than that of traditional methods.

[0012] 2、The iron-based MOF nanocomposite material of the present application shows good thermal stability and structural stability, and still maintains high efficient catalytic performance after multiple uses. After 5 cycles, the COD removal rate still remains above 70%, has excellent regeneration, greatly reduces the processing cost and the replacement frequency of catalyst.

[0013] 3、The preparation process of the present application does not use harmful solvents or chemicals, the material is environmentally friendly and non-toxic, does not produce secondary pollution, meets the requirements of green environmental protection. In addition, the raw material price is low, the preparation process is simple, suitable for large-scale production, can meet the industrialization demand of kitchen waste treatment at low cost.

[0014] 4、Compared with traditional physical and chemical treatment methods, the Fe-MOF nanocomposite material of the present application greatly shortens the degradation period when treating kitchen waste, can complete the decomposition of organic matter in a short time, significantly reduces the energy consumption in the process. The material does not need complex reaction conditions, can realize efficient degradation only under mild temperature and pH conditions, further reduces the overall energy consumption, improves the economic benefit of the treatment. DETAILED DESCRIPTION

[0015] A preparation method of an iron-based MOF nanocomposite for degrading kitchen waste, specifically comprising the following steps: using ferric chloride as a metal source, using N,N-dimethylformamide (DMF) as a solvent, mixing and performing magnetic stirring for 10-15 minutes until completely dissolved, forming a transparent iron ion solution; using 2-methylimidazole as an organic ligand, dissolving in DMF, stirring until completely dissolved, forming a transparent ligand solution; slowly adding the iron ion solution to the ligand solution, stirring while adding, stirring for 10-15 minutes, ensuring uniform mixing, and then continuing to stir for 30-50 minutes to ensure the full uniformity of the precursor solution; transferring the uniformly mixed precursor solution to a 100 mL high-pressure reaction kettle, sealing it and placing it in a constant temperature oven at 100-120 DEG C, and performing a solvothermal reaction for 24-36 hours; after the reaction is completed, the reaction kettle is naturally cooled to room temperature, the reaction liquid is taken out, and a centrifuge is used to centrifuge at a speed of 5000 rpm for 10 minutes to separate the solid product; the obtained solid is washed with anhydrous ethanol and deionized water alternately for 3 times, each time stirring for 5 minutes to remove residual organic matter and unreacted precursors; the washed solid sample is placed in a vacuum drying oven at 60 DEG C and dried for 12 hours until the sample is completely dried, and finally an iron-based MOF nanocomposite is obtained.

[0016] In the preparation method of the iron-based MOF nanocomposite, the amounts of the components are specifically as follows: 5-20 parts by mass of ferric chloride, 5-12 parts by mass of DMF, and 3-10 parts by mass of 2-methylimidazole, and the volume ratio of the iron ion solution to the ligand solution is 1:1-1:10.

[0017] An application of an iron-based MOF nanocomposite in degrading kitchen waste. The degradation process includes: after the Fe-MOF nanocomposite and kitchen waste are fully mixed, stirring is performed at 80-100 r / min, the reaction temperature is controlled at 25 DEG C-35 DEG C, the reaction pH is controlled at 5-8, and after 12 h-24 h of reaction, the degradation is completed. The mass ratio of the Fe-MOF nanocomposite to the kitchen waste is 1:5-1:10.

[0018] The application will be described in detail below in conjunction with the specific embodiments. Example 1

[0019] Take 1.35 grams of ferric chloride as the iron ion source, dissolve it in 30 mL of DMF solution, and use a magnetic stirrer to stir for 10 minutes until it is completely dissolved to form a transparent iron ion solution. Take another 1.64 grams of 2-methylimidazole and dissolve it in 30 mL of DMF, and also stir until completely dissolved to form a transparent ligand solution. Slowly pour the iron ion solution into the ligand solution while stirring, and stir for 10 minutes to ensure uniform mixing. After mixing uniformly, continue stirring for 45 minutes to ensure the uniformity of the precursor solution. Transfer the uniformly mixed precursor solution to a 100 mL Teflon-lined high-pressure reaction kettle, seal it well, and place it in a constant-temperature oven at 100°C for solvothermal reaction for 24 hours. This process ensures the formation of the MOF crystal structure. After the reaction is complete, let the reaction kettle cool naturally to room temperature. Then use a centrifuge at a speed of 5000 rpm for 10 minutes to separate the generated solid product from the solution. The separated solid is washed with anhydrous ethanol and deionized water alternately 3 times, each time stirring for 5 minutes, to remove unreacted residues and impurities. The washed solid sample is placed in a vacuum drying oven at 60°C for 12 hours to dry, obtaining the final Fe-MOF nanocomposite.

[0020] In a 1 L container, add 30 g of Fe-MOF nanocomposite and 150 g of kitchen waste, mix well, and stir at 80 r / min, control the reaction temperature at 25°C, and control the reaction pH at 5. After 12 h of reaction, the degradation is complete. It is determined that the weight loss rate of the kitchen waste is 60%, and the soluble COD proportion increases by 20%. Example 2

[0021] Take 1.35 grams of ferric chloride as the iron ion source, dissolve it in 30 mL of DMF solution, and use a magnetic stirrer to stir for 10 minutes until it is completely dissolved to form a transparent iron ion solution. Take another 1.64 grams of 2-methylimidazole and dissolve it in 35 mL of DMF, and also stir until completely dissolved to form a transparent ligand solution. Slowly pour the iron ion solution into the ligand solution while stirring, and stir for 15 minutes to ensure uniform mixing. After mixing uniformly, continue stirring for 30 minutes to ensure the uniformity of the precursor solution. Transfer the uniformly mixed precursor solution to a 100 mL Teflon-lined high-pressure reaction kettle, seal it well, and place it in a constant-temperature oven at 100°C for solvothermal reaction for 30 hours. This process ensures the formation of the MOF crystal structure. After the reaction is complete, let the reaction kettle cool naturally to room temperature. Then use a centrifuge at a speed of 5000 rpm for 10 minutes to separate the generated solid product from the solution. The separated solid is washed with anhydrous ethanol and deionized water alternately 3 times, each time stirring for 5 minutes, to remove unreacted residues and impurities. The washed solid sample is placed in a vacuum drying oven at 60°C for 12 hours to dry, obtaining the final Fe-MOF nanocomposite.

[0022] In a 1 L container, 50 g of Fe-MOF nanocomposite and 300 g of kitchen waste were thoroughly mixed, stirred at 90 r / min, the reaction temperature was controlled at 30°C, and the reaction pH was controlled at 6. The degradation was completed after 15 h of reaction. It was determined that the weight loss rate of the kitchen waste was 70%, and the soluble COD accounted for an increase of 25%. Example 3

[0023] 6.5 grams of ferric chloride was weighed as an iron ion source and dissolved in 40 mL of DMF solution. A magnetic stirrer was used to stir for 10 minutes until complete dissolution to form a transparent iron ion solution. Another 3.6 grams of 2-methylimidazole was dissolved in 35 mL of DMF, and was also stirred until complete dissolution to form a transparent ligand solution. The iron ion solution was slowly poured into the ligand solution while stirring, and stirring was continued for 15 minutes to ensure uniform mixing. After uniform mixing, stirring was continued for 30 minutes to ensure the uniformity of the precursor solution. The uniformly mixed precursor solution was transferred to a 100 mL Teflon-lined high-pressure reaction kettle, which was sealed and placed in a constant temperature oven at 110°C for solvothermal reaction for 35 hours. This process ensures the formation of MOF crystal structure. After the reaction was completed, the reaction kettle was naturally cooled to room temperature. Then a centrifuge was used at a speed of 5000 rpm for 10 minutes to separate the generated solid product from the solution. The separated solid was washed with anhydrous ethanol and deionized water alternately for 3 times, each time for 5 minutes of stirring, to remove unreacted residues and impurities. The washed solid sample was placed in a vacuum drying oven at 60°C for drying for 12 hours to obtain the final Fe-MOF nanocomposite.

[0024] In a 1 L container, 50 g of Fe-MOF nanocomposite and 250 g of kitchen waste were thoroughly mixed, stirred at 100 r / min, the reaction temperature was controlled at 30°C, and the reaction pH was controlled at 6.5. The degradation was completed after 20 h of reaction. It was determined that the weight loss rate of the kitchen waste was 75%, and the soluble COD accounted for an increase of 30%. Example 4

[0025] Take 3.5 grams of ferric chloride as the iron ion source, dissolve it in 40 mL of DMF solution, and stir it with a magnetic stirrer for 10 minutes until it is completely dissolved to form a transparent iron ion solution. Take another 5.0 grams of 2-methylimidazole and dissolve it in 35 mL of DMF, and also stir it until it is completely dissolved to form a transparent ligand solution. Slowly pour the iron ion solution into the ligand solution while stirring, and stir for 15 minutes to ensure uniform mixing. After uniform mixing, continue stirring for 30 minutes to ensure the uniformity of the precursor solution. Transfer the uniformly mixed precursor solution to a 100 mL Teflon-lined high-pressure reaction kettle, seal it, and place it in a constant-temperature oven at 120°C for 24 hours of solvothermal reaction. This process ensures the formation of the MOF crystal structure. After the reaction is complete, allow the reaction kettle to cool naturally to room temperature. Then use a centrifuge at a speed of 5000 rpm for 10 minutes to separate the generated solid product from the solution. The separated solid is washed with anhydrous ethanol and deionized water alternately 3 times, each time stirring for 5 minutes, to remove unreacted residues and impurities. The washed solid sample is placed in a vacuum drying oven at 60°C for 12 hours to dry, obtaining the final Fe-MOF nanocomposite.

[0026] In a 1 L container, add 80 g of Fe-MOF nanocomposite and 800 g of kitchen waste, mix well, and stir at 80 r / min, control the reaction temperature at 35°C, and control the reaction pH at 7.0. After 24 h of reaction, the degradation is complete. It is determined that the weight loss rate of the kitchen waste is 80%, and the soluble COD proportion increases by 45%. Example 5

[0027] Take 3.5 grams of ferric chloride as the iron ion source, dissolve it in 40 mL of DMF solution, and stir it with a magnetic stirrer for 10 minutes until it is completely dissolved to form a transparent iron ion solution. Take another 5.0 grams of 2-methylimidazole and dissolve it in 35 mL of DMF, and also stir it until it is completely dissolved to form a transparent ligand solution. Slowly pour the iron ion solution into the ligand solution while stirring, and stir for 15 minutes to ensure uniform mixing. After uniform mixing, continue stirring for 30 minutes to ensure the uniformity of the precursor solution. Transfer the uniformly mixed precursor solution to a 100 mL Teflon-lined high-pressure reaction kettle, seal it, and place it in a constant-temperature oven at 120°C for 24 hours of solvothermal reaction. This process ensures the formation of the MOF crystal structure. After the reaction is complete, allow the reaction kettle to cool naturally to room temperature. Then use a centrifuge at a speed of 5000 rpm for 10 minutes to separate the generated solid product from the solution. The separated solid is washed with anhydrous ethanol and deionized water alternately 3 times, each time stirring for 5 minutes, to remove unreacted residues and impurities. The washed solid sample is placed in a vacuum drying oven at 60°C for 12 hours to dry, obtaining the final Fe-MOF nanocomposite.

[0028] In a 1 L container, 30 g of Fe-MOF nanocomposite and 240 g of kitchen waste were mixed well, stirred at 90 r / min, the reaction temperature was controlled at 35°C, and the reaction pH was controlled at 7.5. After 24 h of reaction, the degradation was completed. It was determined that the weight loss rate of kitchen waste was 75%, and the soluble COD accounted for an increase of 33%. Example 6

[0029] 1.5 grams of ferric chloride was weighed as an iron ion source and dissolved in 30 mL of DMF solution. A magnetic stirrer was used to stir for 10 minutes until complete dissolution to form a transparent iron ion solution. Another 3.0 grams of 2-methylimidazole was dissolved in 35 mL of DMF, and also stirred until complete dissolution to form a transparent ligand solution. The iron ion solution was slowly poured into the ligand solution, and stirred while adding, and stirred for 15 minutes to ensure uniform mixing. After uniform mixing, continue to stir for 30 minutes to ensure the uniformity of the precursor solution. The uniformly mixed precursor solution was transferred to a 100 mL Teflon-lined high-pressure reaction kettle, which was sealed and placed in a constant temperature oven at 120°C for solvothermal reaction for 20 hours. This process ensures the formation of MOF crystal structure. After the reaction was completed, the reaction kettle was naturally cooled to room temperature. Then a centrifuge was used at a speed of 5000 rpm for 10 minutes to separate the generated solid product from the solution. The separated solid was washed with anhydrous ethanol and deionized water alternately for 3 times, each time for 5 minutes of stirring, to remove unreacted residues and impurities. The washed solid sample was placed in a vacuum drying oven at 60°C for drying for 12 hours to obtain the final Fe-MOF nanocomposite.

[0030] In a 1 L container, 20 g of Fe-MOF nanocomposite and 140 g of kitchen waste were mixed well, stirred at 80 r / min, the reaction temperature was controlled at 30°C, and the reaction pH was controlled at 6.0. After 18 h of reaction, the degradation was completed. It was determined that the weight loss rate of kitchen waste was 70%, and the soluble COD accounted for an increase of 50%.

[0031] Those skilled in the art can understand that the above embodiments are specific examples for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A method for preparing an iron-based MOF nanocomposite material for the degradation of kitchen waste, characterized in that, Includes the following steps: Using ferric chloride as the metal source and N,N-dimethylformamide as the solvent, the mixture was magnetically stirred for 10-15 minutes until completely dissolved, forming a transparent iron ion solution. 2-Methylimidazole was dissolved in N,N-dimethylformamide and stirred until completely dissolved, forming a transparent ligand solution. The iron ion solution was slowly added to the ligand solution while stirring for 10-15 minutes to ensure uniform mixing, followed by further stirring for 30-50 minutes to ensure complete homogeneity of the precursor solution. The homogeneous precursor solution was transferred to a 100 mL high-pressure reactor, sealed, and placed in a constant temperature oven at 100-120℃ for a solvothermal reaction for 24-36 hours. After the reaction, the reactor was allowed to cool naturally to room temperature. The reaction solution was then removed and centrifuged at 5000 rpm. Centrifuge at rpm for 10 minutes to separate the solid product; wash the obtained solid three times alternately with anhydrous ethanol and deionized water, stirring for 5 minutes each time to remove residual organic matter and unreacted precursors; place the washed solid sample in a vacuum drying oven at 60℃ and dry for 12 hours until the sample is completely dry, finally obtaining the iron-based MOF nanocomposite material.

2. The preparation method according to claim 1, characterized in that, The specific amounts of each component are as follows: 5-20 parts by mass of ferric chloride, 5-12 parts by mass of N,N-dimethylformamide, and 3-10 parts by mass of 2-methylimidazole, wherein the volume ratio of the ferric ion solution to the ligand solution is 1:1 to 1:

10.

3. The application of the iron-based MOF nanocomposite material prepared according to claim 1 in the degradation of kitchen waste, characterized in that, After thoroughly mixing the Fe-MOF nanocomposite material with kitchen waste, the mixture is stirred at 80-100 r / min, the reaction temperature is controlled at 25℃-35℃, the reaction pH is controlled at 5-8, and the degradation is completed after 12-24 h.

4. The application according to claim 3, characterized in that, The mass ratio of Fe-MOF nanocomposite materials to kitchen waste is 1:5-1:

10.

5. The application according to claim 3, characterized in that, After degradation, the weight reduction rate of kitchen waste is 60%-80%, and the proportion of soluble COD increases by 20%-50%.