Waste PET (polyethylene terephthalate) derived carbon loaded Fe monatomic material as well as preparation method and application thereof

Abstract

The invention provides a waste PET derived carbon loaded Fe monatomic material as well as a preparation method and application thereof, and belongs to the technical field of environmental protection and material science. The preparation method comprises the following steps: S1, preparing waste PET into a carbon material; s2, mixing the carbon material with KOH, and sequentially grinding, pyrolyzing, cooling, neutralizing and drying to obtain a first product; s3, mixing and dispersing ferric salt, 1, 10-phenanthroline monohydrate, an ethanol solution and the first product, and then stirring and evaporating to obtain a second product; s4, the second product and melamine are mixed and then sequentially subjected to grinding, calcination, cooling, acid treatment, washing and drying, and the waste PET derived carbon loaded Fe monatomic material is obtained. Therefore, the tetracycline degradation efficiency is remarkably improved, and the tetracycline has good structural stability and chemical stability, is mild in reaction condition and relatively low in cost, and is easy to popularize in practical application.

Description

Technical Field

[0001] The present invention belongs to the technical fields of environmental protection and materials science, and particularly relates to a waste PET-derived carbon-supported Fe single-atom material, a preparation method thereof, and an application thereof. Background Art

[0002] In today's society, environmental protection and resource recycling have become crucial topics. The large generation and accumulation of waste PET plastics have brought a heavy burden to the environment. How to effectively recycle and reuse them is an urgent problem to be solved. At the same time, as a widely used antibiotic, tetracycline residues and accumulation in the environment pose a serious threat to the ecosystem and human health. Existing waste PET plastic treatment methods are often inefficient, costly, and prone to secondary pollution. Many treatment methods simply landfill or incinerate. Landfilling not only occupies a large amount of land resources, but also plastics are difficult to degrade in the natural environment, and long-term existence will affect soil structure and ecological balance; incineration will produce harmful gases and pollute the atmospheric environment.

[0003] Traditional tetracycline degradation methods have many limitations. Physical methods such as adsorption often only transfer tetracycline from one phase to another phase, and do not really achieve its degradation; chemical methods may require the use of a large amount of chemical reagents, which are not only costly but also may introduce new pollutants; biological methods are relatively environmentally friendly, but have a long treatment cycle, unstable effects, and require harsh environmental conditions. In addition, existing persulfate activation methods have problems such as insufficient activity and poor selectivity, resulting in incomplete tetracycline degradation and possible adverse effects on other beneficial substances.

[0004] The present invention aims to solve the above series of technical problems. A new preparation method of a waste PET plastic-derived carbon-based Fe single-atom material is proposed. The material prepared by this method can effectively activate persulfate and achieve efficient degradation of tetracycline. The present invention can convert waste PET plastics into valuable carbon-based materials, realize resource recycling, and reduce the environmental pressure of plastic waste. At the same time, the prepared material has high activity and selectivity, can accurately activate persulfate, enable rapid and complete degradation of tetracycline, and reduce its residues in the environment. The present invention can also avoid secondary pollution and other adverse effects brought by traditional degradation methods, and provide a green, efficient, and sustainable solution for the treatment of waste PET plastics and the degradation of tetracycline.

[0005] In summary, the present invention is committed to solving the problems of waste PET plastic recycling and efficient tetracycline degradation, and making important contributions to environmental protection and sustainable development. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a preparation method of a waste PET-derived carbon-supported Fe single-atom material. The material of the present invention can activate persulfate more quickly and effectively to generate strong oxidizing substances, thereby significantly improving the degradation efficiency of tetracycline; the prepared carbon-based Fe single-atom material has good structural stability and chemical stability, and can still maintain high catalytic activity after being recycled multiple times.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a preparation method of a waste PET-derived carbon-supported Fe single-atom material, comprising the following steps:

[0009] S1. Prepare waste PET into a carbon material;

[0010] S2. Mix the carbon material with KOH, and then successively grind, pyrolyze, cool, neutralize, and dry to obtain a first product;

[0011] S3. Mix and disperse iron salt, 1,10-phenanthroline monohydrate, ethanol solution, and the first product, and then stir and evaporate to obtain a second product;

[0012] S4. Mix the second product and melamine, and then successively grind, calcine, cool, acid-treat, wash, and dry to obtain a waste PET-derived carbon-supported Fe single-atom material.

[0013] Preferably, the specific method for preparing the carbon material from waste PET in S1 is as follows:

[0014] Ball-mill waste PET into PET powder;

[0015] Mix the PET powder with molten salt to obtain a mixture;

[0016] Pyrolyze, cool, pickling, wash, and dry the mixture to obtain a carbon material.

[0017] Preferably, the particle size of the PET powder is 150-200 μm.

[0018] Preferably, the mass ratio of the PET powder to the molten salt is 1:(0.5-10);

[0019] The molten salt is composed of ZnCl 2 and NaCl mixed in a mass ratio of 58:42.

[0020] Preferably, the specific method for pyrolysis is as follows:

[0021] The mixture is heated to 270 - 290 °C at a heating rate of 5 - 10 °C / min under an inert gas atmosphere and held for 8 - 12 min, and then heated to 450 - 650 °C at a heating rate of 5 - 10 °C / min and held for 5 - 8 min.

[0022] Preferably, the pickling is carried out by washing the reaction product with 0.1 M hydrochloric acid.

[0023] The present invention uses a molten salt-assisted strategy to pyrolyze to obtain carbon materials, which have the characteristics of high yield, fast heating, high efficiency, controllable products, and recyclable salts.

[0024] Preferably, the mass ratio of the carbon material to KOH in S2 is 1:2.

[0025] Preferably, the pyrolysis temperature in S2 is 800 °C; the pyrolysis is carried out under an inert gas atmosphere.

[0026] Preferably, the neutralization in S2 is carried out with deionized water.

[0027] Preferably, the ratio of the iron salt, 1,10-phenanthroline monohydrate, ethanol solution, and the first product in S3 is 0.4 mM:2 mM:30 mL:300 mg;

[0028] The iron salt is ferrous acetate or ferrous chloride.

[0029] Preferably, the temperature of stirring and evaporation in S3 is 60 - 70.

[0030] Preferably, the mass ratio of the second product to melamine in S4 is (0.3 - 1):2.

[0031] Preferably, the calcination process in S4 is: calcining at 500 - 600 °C for 1 - 3 h, and then calcining at 650 - 800 °C for 0.5 - 1.5 h.

[0032] Preferably, the pickling in S4 is carried out with 1.0 M H 2 SO 4 for.

[0033] Preferably, the inert gas is nitrogen or argon.

[0034] Preferably, the calcination or pyrolysis is carried out in a tube furnace.

[0035] In a second aspect, the present invention provides a waste PET-derived carbon-supported Fe single-atom material prepared by the above method.

[0036] Thirdly, the present invention provides the application of the above-mentioned waste PET-derived carbon-supported Fe single-atom material in activating persulfate, and the waste PET-derived carbon-supported Fe single-atom material activates persulfate for the degradation of tetracycline.

[0037] It has at least the following beneficial technical effects:

[0038] (1) The present invention converts waste PET plastics into valuable carbon-based Fe single-atom materials, realizing the efficient recycling and reuse of resources and reducing the environmental pressure caused by plastic waste.

[0039] (2) The material prepared by the present invention exhibits excellent catalytic performance. Compared with the conventional catalysts used in the prior art, it can activate persulfate to generate strong oxidizing substances more quickly and effectively, thereby significantly improving the degradation efficiency of tetracycline; the prepared carbon-based Fe single-atom material has good structural stability and chemical stability, and can still maintain high catalytic activity after multiple cycles of use, ensuring the reliability and repeatability in practical applications.

[0040] (3) The present invention uses waste plastics as raw materials, reducing the material cost. At the same time, the efficient degradation performance reduces the usage amount of persulfate, overall reducing the economic cost of treating tetracycline pollution. Moreover, compared with the traditional carbon-based material preparation technology, the preparation process of the present invention is relatively simple, without the need for complex equipment and harsh reaction conditions. This reduces the production cost, improves the production efficiency, and is conducive to large-scale industrial production. In addition to having excellent degradation effects on tetracycline, this material and method are also expected to be applied to the degradation treatment of other organic pollutants, having broad applicability and potential application prospects. Description of the Drawings

[0041] Figure 1 SEM image of 0.5Fe-SA / NPC prepared in Example 1;

[0042] Figure 2 TEM and Mapping images of 0.5Fe-SA / NPC prepared in Example 1;

[0043] Figure 3 AC-HAADF image of 0.5Fe-SA / NPC prepared in Example 1;

[0044] Figure 4 XRD patterns of the carbon-based Fe single-atom materials prepared in Examples 1-5;

[0045] Figure 5 Performance graphs of different obtained catalysts for activating persulfate to degrade tetracycline;

[0046] Figure 6Performance graph of the catalyst obtained in Example 1 for activating persulfate to degrade tetracycline at different dosages;

[0047] Figure 7 Schematic diagram of the synthesis route of the carbon-based Fe single-atom material of the present invention. Detailed implementation manners

[0048] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0049] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0050] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0051] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are only exemplary.

[0052] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0053] The "room temperature" and "normal temperature" mentioned in the present invention are both calculated as 25 ± 2 °C unless otherwise specified.

[0054] Unless otherwise specified, the raw materials or instruments used in the following examples of the present invention are all obtained commercially.

[0055] The waste PET used in the examples of the present invention is the Wahaha mineral water bottle.

[0056] Example 1

[0057] This embodiment provides a method for preparing a waste PET-derived carbon-supported Fe single-atom material, comprising the following steps:

[0058] S1. Prepare carbon material

[0059] Clean and crush waste PET plastic bottles, and then mechanically ball-mill them into waste PET particles with a particle size range of 200 μm using a high-speed ball mill;

[0060] Mix the waste PET particles with molten salt in a mass ratio of 1:2 to obtain a mixture, where the molten salt is obtained by mixing ZnCl 2 and NaCl in a mass ratio of 58:42;

[0061] Put the mixture into an alumina boat, and then put the alumina boat into a tube furnace. At room temperature, introduce nitrogen into the tube furnace, and heat it to 280 °C at a heating rate of 10 °C / min under an inert gas atmosphere and hold for 10 min, then heat it to 550 °C at a heating rate of 10 °C / min and hold for 8 min, and finally cool it to room temperature to obtain a reaction product;

[0062] Wash the reaction product with 0.1 M hydrochloric acid, then wash the reaction product with distilled water until it is neutral, and finally filter and dry it to obtain carbon material.

[0063] S2. Thoroughly mix 6 g of carbon material and 12 g of KOH and grind for 2 hours, then pyrolyze in a tube furnace at 800 °C for 2 hours under an N 2 atmosphere at a rate of 60 mL / min; after cooling overnight, neutralize the obtained powder with deionized water and then dry it in an oven to obtain a first product, named KPC.

[0064] S3. Dissolve 0.5 mM ferrous acetate and 2.5 mM 1,10-phenanthroline monohydrate in 30 mL of ethanol solution and continuously stir for 20 minutes to obtain a mixed solution; to adsorb the Fe(phen) 3 complex, disperse 300 mg of KPC in the above mixed solution, stir at room temperature for 2 hours, and then evaporate the solution at 60 °C under continuous stirring to obtain a second product.

[0065] S4. Grind 0.450 ± 0.008 g of the second product with 2 g of melamine, then transfer it to a quartz boat, calcine it in a tube furnace at 550 °C for 2 hours, then heat it to 700 °C at a heating rate of 5 °C / min and calcine for 1 hour, and then cool it. Use 1.0 M H 2 SO 4The pyrolysis material was acid-treated with (50 mL) for 2 hours to remove unstable iron elements; then the reaction product was washed with distilled water until neutral, and finally filtered and dried to obtain 0.5Fe-SA / NPC, a Fe single-atom doped carbon material.

[0066] Example 2

[0067] The preparation method of this example is the same as that of Example 1, except that in S3, ferrous acetate is 0.1 mM and 1,10-phenanthroline monohydrate is 0.5 mM.

[0068] Example 3

[0069] The preparation method of this example is the same as that of Example 1, except that in S3, ferrous acetate is 0.3 mM and 1,10-phenanthroline monohydrate is 1.5 mM.

[0070] Example 4

[0071] The preparation method of this example is the same as that of Example 1, except that in S3, ferrous acetate is 0.7 mM and 1,10-phenanthroline monohydrate is 3.5 mM.

[0072] Example 5

[0073] The preparation method of this example is the same as that of Example 1, except that in S3, ferrous acetate is 0.9 mM and 1,10-phenanthroline monohydrate is 4.5 mM.

[0074] Example 6

[0075] This example provides a preparation method of a waste PET-derived carbon-supported Fe single-atom material, including the following steps:

[0076] S1. Prepare porous carbon

[0077] Clean and crush the waste PET plastic bottle, and then mechanically ball-mill it into waste PET particles with a particle size range of 150 μm using a high-speed ball mill;

[0078] Mix the waste PET particles with molten salt in a mass ratio of 1:0.5 to obtain a mixture, where the molten salt is composed of ZnCl 2 and NaCl mixed in a mass ratio of 58:42;

[0079] Put the mixture into an alumina boat, and then put the alumina boat into a tube furnace. Argon is introduced into the tube furnace at room temperature, and then heated to 270 °C at a heating rate of 5 °C / min and maintained for 8, and then heated to 450 °C at a heating rate of 5 °C / min and maintained for 5 min, and finally cooled to room temperature to obtain a reaction product;

[0080] The reaction product was washed with 0.1 M hydrochloric acid, then washed with distilled water until neutral, and finally filtered and dried to obtain the carbon material (PC).

[0081] S2. PC (6 g) and KOH (12 g) were thoroughly mixed and ground for 2 hours, and then pyrolyzed at 800 °C for 2 hours in a tubular furnace under an N atmosphere of 60 mL / min; after cooling overnight, the resulting powder was neutralized with deionized water and then dried in an oven to obtain the first product, named KPC. 2 After cooling overnight, the resulting powder was neutralized with deionized water and then dried in an oven to obtain the first product, named KPC.

[0082] S3. 0.5 mM ferrous chloride and 2.5 mM 1,10-phenanthroline monohydrate were dissolved in 30 mL of ethanol solution and continuously stirred for 20 minutes to obtain a mixed solution; to adsorb the Fe(phen) complex, 300 mg of the prepared KPC was dispersed in the above ethanol solution and stirred at room temperature for 2 hours. Then, the solution was evaporated at 70 °C under continuous stirring to obtain the second product; 3 To adsorb the Fe(phen) complex, 300 mg of the prepared KPC was dispersed in the above ethanol solution and stirred at room temperature for 2 hours. Then, the solution was evaporated at 70 °C under continuous stirring to obtain the second product;

[0083] S4. 1 g of the second product was ground with 2 g of melamine, then transferred to a quartz boat and calcined in a tubular furnace at 500 °C for 2 hours, and then heated to 650 °C at a rate of 5 °C / min and calcined for 1 hour. After cooling, the pyrolyzed material was acid-treated with 1.0 M H2SO4 (50 mL) at 70 °C for 2 hours to remove unstable iron elements; then the reaction product was washed with distilled water until neutral, and finally filtered and dried to obtain 0.5Fe-SA / NPC, a Fe single-atom doped carbon material. 2 SO 4 After cooling, the pyrolyzed material was acid-treated with 1.0 M H2SO4 (50 mL) at 70 °C for 2 hours to remove unstable iron elements; then the reaction product was washed with distilled water until neutral, and finally filtered and dried to obtain 0.5Fe-SA / NPC, a Fe single-atom doped carbon material.

[0084] Comparative Example 1

[0085] The preparation method of this comparative example was the same as that of Example 1, except that in S3, ferrous acetate was 0 mM and 1,10-phenanthroline monohydrate was 2.5 mM.

[0086] Experimental Example 1

[0087] 1. The Fe single-atom doped carbon material 0.5Fe-SA / NPC obtained in Example 1 was detected.

[0088] (1) Figure 1 SEM image of the prepared carbon-based Fe single-atom material 0.5Fe-SA / NPC;

[0089] From Figure 1 it can be seen that 0.5Fe-SA / NPC presents a honeycomb-like porous structure, which will provide sufficient contact area for catalytic reactions and expose more active sites during the AOP process.

[0090] (2)Figure 2 TEM and Mapping images of the as-prepared carbon-based Fe single-atom material 0.5Fe-SA / NPC;

[0091] From Figure 2 it can be seen that no obvious nanoparticle lattice was observed in the HR-TEM images, which verified the absence of metal oxides and nanoparticles in 0.5Fe-SA / NC. Additionally, from the mapping images, it can be seen that in the 0.5Fe-SA / NC catalyst, the distributions of C, O, N, and Fe are uniform, further indicating the successful loading of Fe.

[0092] (3) Figure 3 AC-HAADF image of the as-prepared carbon-based Fe single-atom material 0.5Fe-SA / NPC;

[0093] From Figure 3 it can be seen that a large number of isolated bright spots (marked with red circles) in the porous carbon matrix directly prove the atomically dispersed iron in the entire 0.5Fe-SA / NC structure.

[0094] 2. XRD detection was performed on the carbon-based Fe single-atom materials prepared in Examples 1-5

[0095] Figure 4 XRD pattern of the as-prepared carbon-based Fe single-atom material;

[0096] From Figure 4 it can be seen that no characteristic peaks related to iron oxides were observed in each Fe-SA / NC, indicating that the iron-containing crystalline and oxide species did not form or were eluted after acid leaching.

[0097] Experimental Example 2

[0098] Degradation experiment was carried out

[0099] Reagents used in the experiment: Tetracycline (C 22 H 24 N 2 O 8 , 100%, Shanghai Macklin Biochemical Co., Ltd.), persulfate (2KHSO 5 ·KHSO 4 ·K 2 SO 4Analytical pure, Sinopharm Chemical Reagent Co., Ltd.). All degradation experiments were carried out in 150 mL conical flasks, each containing a TC solution with a concentration of 20 mg / L, a PMS solution with a concentration of 0.5 mM, and an Fe-SA / NPC solution with a concentration of 50 mg / L (obtained from each example and comparative example). The initial pH value of the TC solution remained unchanged. 100 mL of the mixed solution was uniformly rotated at a speed of 160 rpm in a constant temperature water bath shaker (T = 25 °C). After the reaction started, an adsorption experiment was first carried out for 30 minutes. After reaching the adsorption equilibrium, PMS was then added to start the catalytic degradation process. After 90 min of reaction, the degradation rate was calculated as shown in Table 1.

[0100] Table 1 Degradation rates of catalysts with different Fe contents

[0101] Case Degradation rate Example 1 (0.5Fe-SA / NPC) 87.58％ Example 2 (0.1Fe-SA / NPC) 84.97％ Example 3 (0.3Fe-SA / NPC) 85.31％ Example 4 (0.7Fe-SA / NPC) 82.94％ Example 5 (0.9Fe-SA / NPC) 77.92％ Comparative Example 1 (0Fe-SA / NPC) 54.72％

[0102] Experimental example 3

[0103] The experimental method was the same as that in Experimental example 2, except that degradation experiments were carried out using different addition amounts of the 0.5Fe-SA / NPC catalyst with different concentrations in Example 1, as shown in Table 2.

[0104] Table 2 Degradation rates of 0.5Fe-SA / NPC with different concentrations

[0105] Different concentrations Degradation rate 10mg / L 79.34％ 30mg / L 85.67％ 70mg / L 87.95％ 100mg / L 89.52％ 0mg / L 10.87％

[0106] The above experimental results show that:

[0107] The catalytic performance has been greatly improved: The waste PET plastic-derived carbon-based Fe single-atom material prepared by adding an iron source shows strong catalytic ability in the process of activating persulfate to degrade tetracycline. Without adding an iron source, the material cannot effectively activate persulfate, resulting in extremely low degradation efficiency of tetracycline or even difficult degradation.

[0108] The reaction rate has been significantly accelerated: Due to the introduction of iron, the material in the present invention can rapidly activate persulfate to generate strongly oxidizing free radicals, thereby accelerating the reaction rate of tetracycline degradation. In contrast, the reaction in the comparative example without adding an iron source progresses slowly and takes a longer time to reach a lower degradation level.

[0109] The degradation effect has been significantly enhanced: Adding an iron source makes the material prepared in the present invention degrade tetracycline more thoroughly. Under the same experimental conditions, the removal rate of tetracycline in the comparative example without adding an iron source is much lower than that in the present invention, and there may be more undegraded tetracycline remaining, unable to achieve the ideal treatment effect.

[0110] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a waste PET-derived carbon-loaded Fe single-atom material, characterized in that: The following steps are involved: S1. Preparing waste PET into carbon materials; S2. The carbon material is mixed with KOH and then subjected to grinding, pyrolysis, cooling, neutralization, and drying to obtain a first product; S3. The iron salt, 1,10-phenanthroline monohydrate, ethanol solution, and the first product are mixed and dispersed and then stirred and evaporated to obtain a second product; S4. The second product and melamine are mixed and then subjected to grinding, calcination, cooling, acid treatment, washing and drying in sequence to obtain a waste PET-derived carbon-loaded Fe single atom material.

2. The preparation method according to claim 1, characterized in that: The specific method for preparing the S1 waste PET into carbon material is: Ball-milling the waste PET into PET powder; mixing the PET powder with molten salt to obtain a mixture; The mixture is pyrolyzed, cooled, acid-washed, washed and dried to obtain a carbon material.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the PET powder to the molten salt is 1:(0.5-10); The molten salt is formed by mixing ZnCl2 and NaCl in a mass ratio of 58:

42.

4. The preparation method according to claim 2, characterized in that: The specific method of the pyrolysis is: The mixture is heated to 270-290° C. at a heating rate of 5-10° C. / min under an inert gas atmosphere and maintained at 8-12 min, and then heated to 450-650° C. at a heating rate of 5-10° C. / min and maintained at 5-8 min.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the carbon material to KOH in the S2 is 1:

2.

6. The preparation method according to claim 1, characterized in that: The ratio of iron salt, 1,10-phenanthroline monohydrate, ethanol solution and the first product in S3 is (0.1-0.9) mM: (0.5-4.5) mM: 30 mL: 300 mg; The iron salt is ferrous acetate or ferrous chloride.

7. The preparation method according to claim 1, characterized in that: The mass ratio of the second product to melamine in S4 is (0.3-1):

2.

8. The preparation method according to claim 1, characterized in that: The calcination process in S4 is: calcining at 500-600° C. for 1-3 h, and then calcining at 650-800° C. for 0.5-1.5 h.

9. A waste PET-derived carbon-loaded Fe single-atom material, characterized in that: The method is prepared by any one of claims 1 to 8.

10. The use of the waste PET derived carbon supported Fe single atom material in activating persulfate according to claim 9, characterized in that: The waste PET-derived carbon-supported Fe single-atom material activates persulfate to degrade tetracycline.

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