Preparation method and application of monatomic iron oxide catalyst based on graphene anchoring

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a preparation method and application of a monatomic iron oxide catalyst based on graphene anchoring. Graphene and ferric chloride are used as raw materials, the monatomic iron oxide catalyst Fe-SA G is prepared through a low-reaction-temperature process, and the preparation method is simple, suitable for large-scale production and low in energy consumption. Experiments prove that the catalyst disclosed by the invention has high catalytic activity and high stability: (1) the catalyst can be used for efficiently treating wastewater containing antibiotics such as tetracycline and the like; and (2) when the catalyst is used for catalyzing persulfate to degrade antibiotics, the stability is high, and the treatment capacity is relatively high.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and in particular to a preparation method and application of a graphene-anchored single-atom iron oxide catalyst. Background Art

[0002] Antibiotic-containing wastewater has become a major challenge in global water pollution control due to its high biotoxicity, recalcitrance, and risk of spreading drug-resistant genes. In recent years, advanced oxidation technologies based on persulfate (PDS) have attracted considerable attention for their high efficiency and broad-spectrum pollutant degradation capabilities, but their treatment efficiency depends primarily on catalyst performance. Traditional technologies such as Fenton oxidation and photocatalysis suffer from issues such as catalyst deactivation, harsh reaction conditions (such as the requirement for a strong acidic environment), and secondary contamination by iron sludge. Single-atom catalysts (SACs) are widely used in pollutant degradation due to their high activity, maximized atom utilization, and minimized catalyst usage. Some researchers have assembled transition metal nanoparticles onto porous materials, which not only exposes more catalytically active sites but also enhances the catalyst's adsorption properties (Journal of Hazardous Materials, 2018, 358; Chemical Reviews, 2021, 121). However, the high adsorption capacity of porous materials can easily lead to the accumulation of catalytic products on the catalyst surface, resulting in reduced catalyst activity or even inactivation. Therefore, it is necessary to identify catalysts with high catalytic activity and stability for the treatment of antibiotic-containing wastewater. Summary of the Invention

[0003] Therefore, based on the above background, the present invention provides a preparation method and application of a graphene-anchored single-atom iron oxide catalyst, which can be prepared with high catalytic activity through a simple operation and low energy consumption method.

[0004] The technical solution provided by the present invention is:

[0005] A method for preparing a graphene-anchored single-atom iron oxide catalyst comprises the following steps:

[0006] S1: Grind graphene powder and ferric chloride powder;

[0007] S2: annealing the material after grinding in step S1 at high temperature in air or oxygen atmosphere;

[0008] S3: After the material annealed in step S2 is cooled, washed, and dried, a single-atom iron oxide catalyst Fe-SA@G is obtained.

[0009] Furthermore, the weight ratio of the graphene powder to the ferric chloride powder in step S1 is 1:(0.1-1).

[0010] Furthermore, in step S2, the annealing temperature is 120-320° C., and the annealing time is controlled within 60-240 min.

[0011] Based on the same inventive concept, the present invention also provides a single-atom iron oxide catalyst prepared by the above-mentioned method for preparing a graphene-anchored single-atom iron oxide catalyst.

[0012] Based on the same inventive concept, the present invention also provides the use of the single-atom iron oxide catalyst in the treatment of organic wastewater.

[0013] Furthermore, the organic wastewater contains antibiotics.

[0014] Furthermore, the antibiotic includes at least one of oxytetracycline, tetracycline, chlortetracycline, doxycycline, ofloxacin and sulfamethoxazole.

[0015] Furthermore, the single-atom iron oxide catalyst catalyzes the oxidation and degradation of antibiotics by a persulfate system.

[0016] The above technical solution has the following beneficial effects:

[0017] The present invention prepares the single-atom iron oxide catalyst Fe-SA@G through a process with a low reaction temperature. The preparation method is simple, suitable for large-scale production, and has low energy consumption.

[0018] The present invention has been experimentally verified to have high catalytic activity and high stability: ① it can efficiently treat wastewater containing antibiotics such as tetracycline; ② the present invention has high stability and large processing capacity when catalyzing the degradation of antibiotics by persulfate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Attachment Figure 1 This is a TEM image of the single-atom Fe-SA@G solid catalyst prepared in Example 1 of the present invention.

[0020] Attachment Figure 2 This is the HR-TEM image of the single-atom Fe-SA@G solid catalyst prepared in Example 1 of the present invention.

[0021] Attachment Figure 3 This is the XRD pattern of the single-atom Fe-SA@G solid catalyst prepared in Example 1 of the present invention.

[0022] Attachment Figure 4 A diagram of the degradation of tetracycline by the single-atom Fe-SA@G solid catalyst prepared in Example 1 of the present invention.

[0023] Attachment Figure 5The mineralization efficiency of the single-atom Fe-SA@G solid catalyst prepared in Example 1 of the present invention for different antibiotic pollutants.

[0024] Attachment Figure 6 Figure b shows the degradation of tetracycline in a catalytic tower equipped with a single-atom Fe-SA@G solid catalyst prepared in Example 3 of the present invention.

[0025] Attachment Figure 7 This is a graph showing the stability test results of the single-atom Fe-SA@G solid catalyst in Example 3 of the present invention. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0028] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0029] In the following examples, high performance liquid chromatography (HPLC) was used to test the concentration of pollutants.

[0030] The technical solution of the present invention is a method for preparing a graphene-anchored single-atom iron oxide catalyst, which comprises the following steps:

[0031] S1: Grind graphene powder and ferric chloride powder;

[0032] In this step, the weight ratio of graphene powder to ferric chloride powder is 1:(0.1-1).

[0033] S2: annealing the material after grinding in step S1 at high temperature in air or oxygen atmosphere;

[0034] In this step, the annealing temperature is 220-320° C., and the annealing time is controlled at 60-240 min. The preferred annealing temperature is 220° C.

[0035] S3: After the material annealed in step S2 is cooled, washed, and dried, a single-atom iron oxide catalyst Fe-SA@G is obtained.

[0036] In this step, the annealed material is naturally cooled.

[0037] In this step, the substrate is first cleaned with acetone and then washed with deionized water to remove residual ferric chloride. Preferably, the drying process is performed by vacuum drying.

[0038] Example 1:

[0039] 10 mg of graphene powder (Shanghai Titan Technology Co., Ltd., single layer, size 100 μm) and 3 mg of ferric chloride powder (Shanghai Titan Technology Co., Ltd., analytical grade (AR)) were weighed and placed in an agate mortar and manually ground for 10 min. The graphene was then annealed at 220 °C for 2 h in an air atmosphere using a muffle furnace.

[0040] After naturally cooling to room temperature, the synthesized powder material was first washed with acetone and then with deionized water to remove residual ferric chloride, and finally vacuum dried to obtain the single-atom iron oxide catalyst Fe-SA@G;

[0041] The Fe-SA@G catalysts prepared above were characterized separately. The characterization results are shown in Figures 1 to 3 ,

[0042] according to Figures 1-2 The TEM and HRT images show that in the Fe-SA@G catalyst of the present invention, a single-atom Fe2O3 catalyst (Fe-SA@G) is anchored on the graphene substrate. The Fe-SA@G catalyst was subjected to XRD test, and the test results are shown in FIG. Figure 3 .Depend on Figure 3 It can be seen that Bragg peaks are found at 24.0, 32.9, 40.6, 49.4 and 53.8°, which are consistent with the 2θ values of Fe2O3 crystals. This shows that the catalytically active component in the solid catalyst prepared by the present invention is Fe2O3 catalyst.

[0043] Next, the effect of Fe-SA@G catalyst in catalyzing the degradation of tetracycline by PDS was verified.

[0044] 10 mg of the prepared Fe-SA@G catalyst was weighed and placed in a reaction reagent bottle. 10 ml of a 20 ppm tetracycline (Shanghai Titan Technology Co., Ltd., analytical grade (AR)) solution (prepared by adding tetracycline to purified water) was added. Ultrasonication or continuous stirring was performed for 10 min. After reaching adsorption equilibrium, the pH value of the solution was adjusted to 13 using 0.1 M sodium hydroxide solution or sulfuric acid. 0.4 mM PDS (peroxydisulfate) solution was added and the reaction was stirred at 700 rpm for 2 h.

[0045] Then, after 0, 15, 30, 45, 60, 90, and 120 min of reaction, 1 ml of methanol was added, the mixture was shaken vigorously to quench, and immediately filtered with a 0.22 μm filter head and placed in a liquid phase vial. The concentration of pollutants in the sample was determined by high performance liquid chromatography (HPLC), and the degradation rate of organic pollutants was further calculated. The results are shown in Figure 4 ,Depend on Figure 4 It can be seen that the degradation efficiency of tetracycline reaches 100% within 90 min, indicating that the prepared catalyst has excellent catalytic performance.

[0046] Example 2: This example verifies the catalytic performance of the Fe-SA@G catalyst of the present invention in the degradation of different antibiotics by PDS.

[0047] 20mL of 20ppm pollutant solution (oxytetracycline, tetracycline, chlortetracycline, doxycycline, ofloxacin and sulfamethoxazole) (prepared by adding antibiotics to purified water) was added to a 50mL glass beaker containing 10mg of the single-atom Fe-SA@G catalyst prepared in Example 1. After continuous stirring or ultrasound to reach adsorption equilibrium, 0.4mM PDS was added to initiate the reaction. The entire experiment was stirred for 4h without adjusting the pH value (the initial pH value was around 5). The total organic carbon (TOC) value was measured using a total organic carbon analyzer (multi-3100, Analytik Jena) to further calculate the mineralization efficiency of organic pollutants. The results are shown in Figure 2. Figure 5 .

[0048] from Figure 5 It can be seen that the chemical oxygen demand (TOC) removal rate of different antibiotic pollutants such as oxytetracycline, tetracycline, chlortetracycline, doxycycline, ofloxacin and sulfamethoxazole reached >70.0% within 6 h.

[0049] Example 3: This example simulates the cyclic stability of the Fe-SA@G catalyst in actual wastewater treatment.

[0050] In order to simulate the application of Fe-SA@G catalyst in actual wastewater treatment, a continuous treatment system was built, such as Figure 6 As shown, the continuous treatment system includes a vertical circulation tower filled with Fe-SA@G catalyst. The feed port at the bottom of the circulation tower is connected to a wastewater storage cup via a feed pump. The feed pump transfers wastewater from the wastewater storage cup to the circulation tower. The discharge port at the top of the circulation tower is connected to the wastewater storage cup via a hose. In other words, after the wastewater in the wastewater storage cup is treated in the circulation tower, it is returned to the wastewater storage cup and then further pumped to the circulation tower via the feed pump, thus completing the circulation process.

[0051] The catalytic tower is constructed as follows:

[0052] Add 100 mg of Fe-SA@G catalyst to a large beaker filled with 1.0 L of deionized water. Soak a 1 cm × 1 cm × 1 cm melamine sponge in the catalyst solvent and ultrasonicate for 30 minutes. Dry the sponge in a 150°C oven for 2 hours to obtain a catalyst-loaded sponge. Then, fill the catalytic circulation tower with the catalyst-loaded sponge.

[0053] Specifically, 20 mg / L tetracycline solution was prepared in wastewater, 0.4 mM PDS was added, 15 L of wastewater was added to the wastewater storage cup, and the wastewater was transported to the circulation tower through the feed pump at a flow rate of 150 mL / min, and then returned to the wastewater storage cup for circulation. After continuous operation for 8 hours, it was a cycle; after 8 hours, the tetracycline content in the wastewater in the wastewater storage cup was tested; after 8 hours, new wastewater was taken from the wastewater storage cup, and the wastewater was continued to be transported to the circulation tower through the feed pump at a flow rate of 150 mL / min, and then returned to the wastewater storage cup for circulation, which was the next cycle; as above, the cycle was continued for ten times, a total of 12 cycles. After each cycle, the concentration of tetracycline pollutants was measured by high performance liquid chromatography (HPLC), and the degradation rate of the antibiotic was further calculated. The results are shown in FIG. Figure 7 .from Figure 7 It is obvious that after the twelfth cycle, the catalyst still has stable catalytic degradation ability.

[0054] The above description of the present invention and its embodiments is non-limiting and the actual embodiments are not limited thereto. In short, if a person skilled in the art is inspired by the above description and designs an implementation method and embodiment similar to the technical solution without departing from the purpose of the present invention, they shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene-anchored single-atom iron oxide catalyst, characterized in that: It includes the following steps: S1: Grind graphene powder and ferric chloride powder; S2: annealing the material after grinding in step S1 at high temperature in air or oxygen atmosphere; S3: After the material annealed in step S2 is cooled, washed, and dried, a single-atom iron oxide catalyst Fe-SA@G is obtained.

2. The method for preparing a graphene-anchored single-atom iron oxide catalyst according to claim 1, wherein: The weight ratio of the graphene powder to the ferric chloride powder in step S1 is 1:(0.1-1).

3. The method for preparing a graphene-anchored single-atom iron oxide catalyst according to claim 1, wherein: In step S2, the annealing temperature is 120-320° C., and the annealing time is controlled within 60-240 min.

4. The method for preparing a graphene-anchored single-atom iron oxide catalyst according to claim 3, wherein: The annealing temperature in step S2 is 120-220°C.

5. A single-atom iron oxide catalyst prepared by the method for preparing a graphene-anchored single-atom iron oxide catalyst according to any one of claims 1 to 5.

6. Use of the monatomic iron oxide catalyst according to claim 5 in the treatment of organic wastewater.

7. The use according to claim 6, characterized in that The organic wastewater contains antibiotics.

8. The use according to claim 7, characterized in that The antibiotics include at least one of oxytetracycline, tetracycline, chlortetracycline, doxycycline, ofloxacin and sulfamethoxazole.

9. The use according to claim 8, characterized in that The single-atom iron oxide catalyst catalyzes the oxidation and degradation of antibiotics by a persulfate system.

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