Fenton-like catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a Fenton-like catalyst as well as a preparation method and application thereof. The Fenton-like catalyst is a granular iron monatomic catalyst; the raw materials comprise a powdery iron monatomic catalyst, modified bentonite, carbon nanofibers and ammonium bicarbonate. The preparation method of the catalyst comprises the following steps: (1) preparing a precursor solution; (2) preparing a metal iron organic precursor; (3) preparing a powdery iron monatomic catalyst; (4) preparing plastic slurry; and (5) preparing the granular iron monatomic catalyst. The Fenton-like catalyst can be used for advanced treatment of sewage, and various new pollutants can be efficiently degraded without adding an oxidizing agent.

Description

Technical Field

[0001] This invention belongs to the technical field of wastewater treatment, specifically relating to a Fenton-like catalyst, its preparation method, and its application. Background Technology

[0002] With the rapid development of industries such as pharmaceuticals and chemicals, large quantities of newly synthesized antibiotics are being discharged into the aquatic environment through wastewater. As a typical new pollutant, antibiotics, due to their extremely high chemical stability and resistance to biodegradation, can persist and accumulate in the aquatic environment for a long time. Simultaneously, their strong biotoxicity not only directly harms the structure of aquatic organism populations but also, through the food chain, induces cumulative health risks such as gene mutations in the human body. However, because new pollutants such as antibiotics are difficult to remove effectively by conventional water treatment processes, they pose a continuous threat to drinking water safety and ecosystem stability, becoming a severe challenge in current water pollution control.

[0003] In recent years, heterogeneous Fenton systems have been widely developed for the remediation of wastewater. However, various Fenton systems generally rely on the continuous addition of high concentrations of peroxides (such as PMS and H2O2), and the utilization rate of oxidants is severely low due to free radical quenching and mass transfer limitations. In addition, residual peroxides not only inhibit the activity of aquatic organisms but may also cause environmental risks such as secondary pollution of water bodies, which has become a major bottleneck limiting their practical application. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of current Fenton-like systems that rely on high concentrations of peroxides by providing a Fenton-like catalyst, its preparation method, and its applications. Using the described Fenton-like catalyst for advanced wastewater treatment, a variety of novel pollutants can be efficiently degraded without the addition of external oxidants.

[0005] The preparation of the Fenton-like catalyst described in this invention first involves the precise preparation of an iron-based organic precursor through in-situ coordination polymerization, followed by high-temperature pyrolysis to obtain a powdered iron single-atom catalyst. The powdered iron single-atom catalyst is then mixed with modified bentonite, carbon nanofibers, and ammonium bicarbonate, extruded, and sintered to obtain a granular iron single-atom catalyst.

[0006] The technical solution of this invention is as follows: A Fenton-like catalyst is a granular iron single-atom catalyst with a particle size of 2-3 mm. The granular iron single-atom catalyst includes the following raw materials: powdered iron single-atom catalyst, modified bentonite, carbon nanofibers and ammonium bicarbonate; wherein the mass ratio of powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate is (75-80):(13-18):3:4.

[0007] The raw materials for the powdered iron single-atom catalyst include 2-methylimidazole, zinc nitrate hexahydrate and iron acetylacetone; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methylimidazole is 1:(5-6):(30-35).

[0008] The Fenton-like catalyst is prepared by the following steps: (1) Preparation of precursor solution 2-Methylimidazole and zinc nitrate hexahydrate were added to methanol and stirred until homogeneous to obtain a precursor solution; wherein the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole was 1:(5-7), and the mass ratio of zinc nitrate hexahydrate to methanol volume was 1g:(27-30)mL.

[0009] (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for at least 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:(5-6); The solution of the iron-organic precursor was centrifuged, the precipitate was collected and dried to obtain the iron-organic precursor.

[0010] (3) Preparation of powdered iron single-atom catalyst The organic precursor of metallic iron obtained in step (2) was placed in a N2 atmosphere and calcined at a constant temperature of 1100-1200℃ for 2-3 hours; after the calcination was completed, it was cooled to room temperature to obtain a powdered iron single-atom catalyst.

[0011] (4) Preparation of plastic slurry The powdered iron single-atom catalyst obtained in step (3) is mixed with raw material modified bentonite, carbon nanofibers and ammonium bicarbonate in a certain proportion to obtain the total material; deionized water is added to the total material and stirred and plasticized to obtain a uniform plastic slurry. The mass ratio of powdered iron single-atom catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate is (75-80):(13-18):3:4; the amount of deionized water added is 30-35 wt% of the total material mass.

[0012] (5) Preparation of particulate iron single-atom catalyst The plastic slurry obtained in step (4) is extruded and molded, dried and dehydrated, and then sintered in a N2 atmosphere at 600-650°C. After cooling, granular iron single-atom catalyst is obtained.

[0013] In this invention, the raw material powdered iron single-atom catalyst of the Fenton-like catalyst has a porous carbon framework structure, with N element uniformly dispersed in the porous carbon framework, and Fe element forming a spatially correlated Fe-N co-location network with N element.

[0014] The powdered iron single-atom catalyst possesses a porous carbon framework structure with a clean surface free of visible particles. Furthermore, the carbon support exhibits only amorphous carbon streaks, completely lacking the characteristic lattice of iron, iron oxide, or iron carbide nanoparticles. In addition, nitrogen (N) is uniformly dispersed within the carbon framework, while fe (Fe) exhibits an atomically dispersed pattern that highly overlaps with the nitrogen distribution, forming a spatially correlated Fe-N co-localized network. This demonstrates that iron in the powdered iron single-atom catalyst is chemically anchored to nitrogen sites without localized aggregation, while the carbon framework structure remains intact.

[0015] In this invention, the Fenton-like catalyst is made from carbon nanofibers with a diameter of 80-85 nm.

[0016] In this invention, the Fenton-like catalyst has a raw material of powdered iron single-atom catalyst with a particle size of 1-3 μm.

[0017] In this invention, the particulate iron single-atom catalyst has a porosity of 55-65% and a specific surface area of ​​800-1000 m². 2 / g; abrasion index is 1.5-2.5%; compressive strength is 12-18MPa.

[0018] A method for preparing the aforementioned Fenton-like catalyst includes the following steps: (1) Preparation of precursor solution 2-Methylimidazole and zinc nitrate hexahydrate were added to methanol and stirred until homogeneous to obtain a precursor solution. The molar ratio of zinc nitrate hexahydrate to 2-methylimidazole was 1:(5-7), and the mass ratio of zinc nitrate hexahydrate to methanol volume was 1 g:(27-30) mL.

[0019] (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for at least 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:(5-6); The solution of the iron-organic precursor was centrifuged, the precipitate was collected and dried to obtain the iron-organic precursor.

[0020] (3) Preparation of powdered iron single-atom catalyst The organic precursor of metallic iron obtained in step (2) was placed in a N2 atmosphere and calcined at a constant temperature of 1100-1200℃ for 2-3 hours; after the calcination was completed, it was cooled to room temperature to obtain a powdered iron single-atom catalyst.

[0021] (4) Preparation of plastic slurry The powdered iron single-atom catalyst obtained in step (3) is mixed with the raw material modified bentonite (Al2O3·4SiO2), carbon nanofibers and pore-forming agent ammonium bicarbonate in a certain proportion to obtain the total material; deionized water is added to the total material and stirred and plasticized to obtain a uniform plastic slurry. The mass ratio of powdered iron single-atom catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate is (75-80):(13-18):3:4; the amount of deionized water added is 30-35 wt% of the total material mass.

[0022] (5) Preparation of particulate iron single-atom catalyst The plastic slurry obtained in step (4) is extruded and molded, dried and dehydrated, and then sintered at 600-650℃ for 2-3 hours in N2 atmosphere. After cooling, a granular iron single-atom catalyst with regular size is obtained.

[0023] In the preparation method of the Fenton-like catalyst in this invention, the centrifugation rate in step (2) is 8000 rpm, centrifuged 3 times, and the centrifugation time is 4 min each time. The precipitate is washed with ethanol during the centrifugation process.

[0024] In the preparation method of the Fenton-like catalyst in this invention, the N2 flow rate in step (3) is 100-150 mL / min; the temperature is increased to 1100-1200℃ at a heating rate of 5℃ / min; and the temperature is cooled to room temperature at a cooling rate of 10℃ / min.

[0025] In this invention, the preparation method of the Fenton-like catalyst, in step (5), uses a twin-screw extruder for extrusion molding; wherein the rotation speed of the twin screw is 25-30 rpm and the die pressure is 18-20 MPa.

[0026] In the preparation method of the Fenton-like catalyst in this invention, step (5) involves air drying and dehydration at 100-105℃ for 2-3 hours; N2 flow rate of 100-150 mL / min; heating to 600-650℃ at a heating rate of 2℃ / min; and cooling at a controlled temperature rate of 5℃ / min.

[0027] The above-mentioned Fenton-like catalysts are used in advanced wastewater treatment (especially for new pollutant wastewater). Applicable wastewater pollutants (new pollutants) include: ibuprofen (PCM), sulfamethoxazole (SMZ), bisphenol A (BPA), carbamazepine (CBZ), ciprofloxacin (CIP), etc.

[0028] A method for deep treatment of wastewater using the aforementioned Fenton-like catalyst includes the following steps: First, Fenton-like catalyst particles are filled into a continuous flow bed reactor to form a Fenton-like catalyst bed with a filling height of 200-300 cm.

[0029] Subsequently, purified water is injected from the bottom of the continuous flow bed reactor at a flow rate of 5-8 m / h. The uniform stacking of the Fenton-like catalyst bed is achieved through the synergistic effect of hydraulic load and material settling, and the bed is then cleaned.

[0030] The wastewater requiring advanced treatment can be introduced into a continuous fluidized bed reactor for wastewater treatment.

[0031] The bottom of the continuous flow bed reactor is equipped with a swirl distributor with a 15° tilt angle. The swirl distributor has an annular array of openings with a diameter of 3-4 mm.

[0032] A layer of alumina ceramic balls with a height of 15-20 cm is laid at the bottom of the continuous flow bed reactor, wherein the particle size of the alumina ceramic balls is 3-5 mm, to achieve water pre-distribution.

[0033] A stainless steel anti-escape screen with a aperture of 1-2 mm is installed at the top of the continuous flow bed reactor.

[0034] This continuous fluidized bed reactor has three functions: water pre-distribution, prevention of packing expansion, and prevention of packing loss. It can continuously operate the catalytic reaction and carry out comprehensive deep treatment of the effluent after biochemical treatment. It can avoid the construction requirements of multi-stage deep treatment systems and significantly reduce the construction cost of wastewater deep treatment facilities.

[0035] The aforementioned Fenton-like catalyst, combined with the continuous flow catalytic reactor, enables highly efficient and advanced treatment of the effluent after biochemical treatment, achieving long-term stable removal of new pollutants. Furthermore, the lower sludge production also helps alleviate the burden of chemical sludge treatment and disposal.

[0036] The beneficial effects of this invention are as follows: The Fenton-like catalyst described in this invention has a precise coordination structure, forming a dual reaction center with electron-poor / electron-rich microregions on its surface. Pollutants in biochemical wastewater are adsorbed in the electron-poor region as electron donors and transfer electrons. Electrons are transferred to the electron-rich region through bonding bridges on the catalyst surface. The iron single atom in this Fenton-like catalyst acts as the main electron acceptor, efficiently capturing electrons from pollutants, thereby achieving efficient and selective degradation of new pollutants without the addition of oxidants. This process completely eliminates the dependence of traditional processes on exogenous oxidants such as persulfate and ozone, not only eliminating the risks of chemical reagent storage and transportation and residual toxicity, but also significantly reducing equipment investment and energy consumption. In complex water conditions (such as high chloride ion and carbonate systems), the electron transfer mechanism can avoid the free radical quenching effect, maintaining excellent degradation efficiency, while dissolved oxygen-driven iron valence state cycling (Fe 2+ / Fe 3+ This enables the catalyst to have self-regeneration capabilities.

[0037] Compared to traditional reactors, the continuous fluidized bed reactor has advantages such as high mass transfer efficiency, strong anti-fouling ability (avoiding catalyst passivation), and low energy consumption. It can achieve deep degradation of new pollutants in a short residence time and has excellent degradation rate of new pollutants, providing an efficient and reliable path for the engineering treatment of highly toxic new pollutants.

[0038] Loading the aforementioned Fenton-like catalyst into a continuous fluidized bed reactor enables highly efficient and sustainable removal of pollutants through its unique dynamic mass transfer and electron synergy mechanism, while also withstanding fluctuations in water quality. When polluted water flows through the reactor, turbulence forces pollutant molecules to preferentially adsorb onto the catalyst surface and transfer electrons. At this point, iron single atoms act as core electron acceptors, efficiently capturing electrons to achieve long-term stable removal of pollutants. Simultaneously, the continuous operation of the fluidized bed promotes dynamic catalyst regeneration. Degradation products are flushed away from the active sites by the fluid in real time, while the oxygen reduction reaction continuously repairs the oxidation state of the catalytic sites, forming a self-circulating system. Attached Figure Description

[0039] Figure 1 This is a transmission electron microscope image of a powdered iron single-atom catalyst at 200 nm.

[0040] Figure 2 This is a transmission electron microscope image of a powdered iron single-atom catalyst at 5 nm.

[0041] Figure 3 This is the energy spectrum distribution of a powdered iron single-atom catalyst.

[0042] Figure 4 This is a schematic diagram illustrating the principle of the Fenton-like deep treatment method for novel pollutants in wastewater according to the present invention. Detailed Implementation

[0043] The technical solution of the present invention will be described in detail below.

[0044] The specific steps of the method for deep treatment of wastewater using the aforementioned Fenton-like catalyst are as follows: First, Fenton-like catalyst particles are filled into a continuous flow bed reactor to form a Fenton-like catalyst bed with a filling height of 200 cm.

[0045] Subsequently, clean water is injected from the bottom of the continuous flow bed reactor at a flow rate of 8 m / h to ensure uniform deposition of the Fenton-like catalyst bed and to clean the bed.

[0046] The wastewater requiring advanced treatment can be introduced into a continuous fluidized bed reactor for wastewater treatment.

[0047] The bottom of the continuous flow bed reactor is equipped with a swirl distributor with a 15° tilt angle. The swirl distributor has an annular array of openings with a diameter of 4 mm.

[0048] A layer of alumina ceramic balls with a height of 15 cm and a particle size of 3 mm is laid at the bottom of the continuous flow bed reactor.

[0049] A stainless steel anti-escape screen with a 1mm aperture is installed at the top of the continuous fluidized bed reactor.

[0050] Example 1 The Fenton-like catalyst is a granular iron single-atom catalyst, and its raw materials are as follows: powdered iron single-atom catalyst, modified bentonite, carbon nanofibers with a diameter of 80 nm and ammonium bicarbonate; wherein, the mass ratio of powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate is 78:15:3:4.

[0051] The raw materials for the powdered iron single-atom catalyst include 2-methylimidazole, zinc nitrate hexahydrate, and iron acetylacetone; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methylimidazole is 1:6:30.

[0052] The specific steps for preparing the Fenton-like catalyst are as follows: (1) Preparation of precursor solution Zinc nitrate hexahydrate and 2-methylimidazole were added to methanol at a molar ratio of 1:5 and stirred until homogeneous to obtain a precursor solution; wherein the mass ratio of zinc nitrate hexahydrate to the volume ratio of methanol was 1:27 g / mL.

[0053] (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:6.

[0054] The solution of the iron-organic precursor was centrifuged, the precipitate was collected and dried to obtain the iron-organic precursor. The centrifugation rate was 8000 rpm, and the centrifugation was performed 3 times, with each centrifugation time being 4 min. The precipitate was rinsed with ethanol during the centrifugation process.

[0055] (3) Preparation of powdered iron single-atom catalyst The organic precursor of metallic iron obtained in step (2) was placed in a N2 atmosphere and heated to 1100℃ at a heating rate of 5℃ / min for 2 hours. After the calcination was completed, it was cooled to room temperature at a cooling rate of 10℃ / min to obtain a powdered iron single-atom catalyst. The N2 flow rate was 100mL / min.

[0056] (4) Preparation of plastic slurry The powdered iron single-atom catalyst obtained in step (3) is mixed with raw material modified bentonite (Al2O3·4SiO2), carbon nanofibers and pore-forming agent ammonium bicarbonate in a certain proportion to obtain the total material; deionized water is added to the total material and stirred and plasticized to obtain a uniform plastic slurry.

[0057] The mass ratio of powdered iron single-atom catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate is 78:15:3:4; the amount of deionized water added is 35 wt% of the total material mass.

[0058] (5) Preparation of particulate iron single-atom catalyst The plastic slurry obtained in step (4) is extruded into granules using a twin-screw extruder; wherein the twin-screw speed is 25 rpm and the die pressure is 18 MPa.

[0059] After air drying and dehydration at 105℃ for 3 hours, the catalyst was sintered in an N2 atmosphere at a heating rate of 2℃ / min to 600℃ for 2 hours. After cooling at a controlled temperature of 5℃ / min, granular iron single-atom catalyst with a regular particle size of 2mm was obtained. The N2 flow rate was 100mL / min.

[0060] Example 2 The Fenton-like catalyst is a granular iron single-atom catalyst, and its raw materials are as follows: powdered iron single-atom catalyst, modified bentonite, carbon nanofibers and ammonium bicarbonate; wherein, the mass ratio of powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate is 75:18:3:4.

[0061] The raw materials for the powdered iron single-atom catalyst include 2-methylimidazole, zinc nitrate hexahydrate, and iron acetylacetone; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methylimidazole is 1:5:35.

[0062] The specific steps for preparing the Fenton-like catalyst are as follows: (1) Preparation of precursor solution Zinc nitrate hexahydrate and 2-methylimidazole were added to methanol at a molar ratio of 1:7 and stirred until homogeneous to obtain a precursor solution; wherein the mass ratio of zinc nitrate hexahydrate to the volume ratio of methanol was 1:30 g / mL.

[0063] (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:5.

[0064] The solution of the iron-organic precursor was centrifuged, the precipitate was collected and dried to obtain the iron-organic precursor. The centrifugation rate was 8000 rpm, and the centrifugation was performed 3 times, with each centrifugation time being 4 min. The precipitate was rinsed with ethanol during the centrifugation process.

[0065] (3) Preparation of powdered iron single-atom catalyst The organic precursor of metallic iron obtained in step (2) was placed in a N2 atmosphere and heated to 1200℃ at a heating rate of 5℃ / min for 2 hours. After the calcination was completed, it was cooled to room temperature at a cooling rate of 10℃ / min to obtain a powdered iron single-atom catalyst. The N2 flow rate was 150mL / min.

[0066] (4) Preparation of plastic slurry The powdered iron single-atom catalyst obtained in step (3) is mixed with raw material modified bentonite (Al2O3·4SiO2), carbon nanofibers and pore-forming agent ammonium bicarbonate in a certain proportion to obtain the total material; deionized water is added to the total material and stirred and plasticized to obtain a uniform plastic slurry.

[0067] The mass ratio of powdered iron single-atom catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate is 75:18:3:4; the amount of deionized water added is 30 wt% of the total material mass.

[0068] (5) Preparation of particulate iron single-atom catalyst The plastic slurry obtained in step (4) is extruded into granules using a twin-screw extruder, wherein the twin screw speed is 30 rpm and the die pressure is 20 MPa.

[0069] After air drying and dehydration at 105℃ for 3 hours, the catalyst was sintered in an N2 atmosphere at a heating rate of 2℃ / min to 650℃, followed by controlled cooling at a cooling rate of 5℃ / min to obtain granular iron single-atom catalysts with regular particle size of 3mm. The N2 flow rate was 150mL / min.

[0070] Example 3 The Fenton-like catalyst is a granular iron single-atom catalyst, and its raw materials are as follows: powdered iron single-atom catalyst, modified bentonite, carbon nanofibers and ammonium bicarbonate; wherein, the mass ratio of powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate is 80:13:3:4.

[0071] The raw materials for the powdered iron single-atom catalyst include 2-methylimidazole, zinc nitrate hexahydrate, and iron acetylacetone; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methylimidazole is 1:6:30.

[0072] The specific steps for preparing the Fenton-like catalyst are as follows: (1) Preparation of precursor solution Zinc nitrate hexahydrate and 2-methylimidazole were added to methanol at a molar ratio of 1:5 and stirred until homogeneous to obtain a precursor solution; wherein the mass ratio of zinc nitrate hexahydrate to the volume ratio of methanol was 1:27 g / mL.

[0073] (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:6.

[0074] The solution of the iron-organic precursor was centrifuged, the precipitate was collected and dried to obtain the iron-organic precursor. The centrifugation rate was 8000 rpm, and the centrifugation was performed 3 times, with each centrifugation time being 4 min. The precipitate was rinsed with ethanol during the centrifugation process.

[0075] (3) Preparation of powdered iron single-atom catalyst The organic precursor of metallic iron obtained in step (2) was placed in a N2 atmosphere and heated to 1100℃ at a heating rate of 5℃ / min for 2 hours. After the calcination was completed, it was cooled to room temperature at a cooling rate of 10℃ / min to obtain a powdered iron single-atom catalyst. The N2 flow rate was 100mL / min.

[0076] (4) Preparation of plastic slurry The powdered iron single-atom catalyst obtained in step (3) is mixed with raw material modified bentonite (Al2O3·4SiO2), carbon nanofibers and pore-forming agent ammonium bicarbonate in a certain proportion to obtain the total material; deionized water is added to the total material and stirred and plasticized to obtain a uniform plastic slurry.

[0077] The mass ratio of powdered iron single-atom catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate is 80:13:3:4; the amount of deionized water added is 35 wt% of the total material mass.

[0078] (5) Preparation of particulate iron single-atom catalyst The plastic slurry obtained in step (4) is extruded into granules using a twin-screw extruder, wherein the twin screw speed is 25 rpm and the die pressure is 18 MPa.

[0079] After air drying and dehydration at 105℃ for 3 hours, the catalyst was sintered in an N2 atmosphere at a heating rate of 2℃ / min to 600℃, followed by controlled cooling at a cooling rate of 5℃ / min to obtain granular iron single-atom catalyst with a regular particle size of 2mm. The N2 flow rate was 100mL / min.

[0080] Comparative Example 1 The difference from Example 1 is that the catalyst in this comparative example is a powdered iron single-atom catalyst, and the raw materials include 2-methylimidazole, zinc nitrate hexahydrate and iron acetylacetone; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methylimidazole is 1:6:30.

[0081] The preparation method of the catalyst includes the following specific steps: (1) Preparation of precursor solution Zinc nitrate hexahydrate and 2-methylimidazole were added to methanol at a molar ratio of 1:5 and stirred until homogeneous to obtain a precursor solution; wherein the mass ratio of zinc nitrate hexahydrate to the volume ratio of methanol was 1:27 g / mL.

[0082] (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:6.

[0083] The solution of the iron-organic precursor was centrifuged, the precipitate was collected and dried to obtain the iron-organic precursor. The centrifugation rate was 8000 rpm, and the centrifugation was performed 3 times, with each centrifugation time being 4 min. The precipitate was rinsed with ethanol during the centrifugation process.

[0084] (3) Preparation of powdered iron single-atom catalyst The organic precursor of metallic iron obtained in step (2) was placed in a N2 atmosphere and heated to 1100℃ at a heating rate of 5℃ / min for 2 hours. After the calcination was completed, it was cooled to room temperature at a cooling rate of 10℃ / min to obtain a powdered iron single-atom catalyst. The N2 flow rate was 100mL / min.

[0085] Comparative Example 2 The difference from Example 1 is that it does not contain carbon nanofibers.

[0086] The granular iron single-atom catalyst of this comparative example is made from the following raw materials: powdered iron single-atom catalyst, modified bentonite, and ammonium bicarbonate; wherein the mass ratio of powdered iron single-atom catalyst: modified bentonite: ammonium bicarbonate is 78:18:4.

[0087] The preparation of the catalyst, step (4) of preparing the plastic slurry, is as follows: The obtained powdered iron single-atom catalyst was mixed with modified bentonite (Al2O3·4SiO2) and pore-forming agent ammonium bicarbonate in a certain proportion to obtain the total material; deionized water was added to the total material and stirred and plasticized to obtain a uniform plastic slurry.

[0088] The mass ratio of powdered iron single-atom catalyst, modified bentonite, and ammonium bicarbonate is 78:18:4.

[0089] The others are the same as in Example 1.

[0090] Comparative Example 3 The difference from Example 1 is that the granular iron single-atom catalyst of this comparative example has the following raw materials: powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate in a mass ratio of 70:23:3:4.

[0091] Comparative Example 4 The difference from Example 1 is that the granular iron single-atom catalyst of this comparative example has the following raw materials: powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate in a mass ratio of 85:8:3:4.

[0092] Comparative Example 5 The difference from Example 1 is that the granular iron single-atom catalyst of this comparative example has the following raw materials: powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate in a mass ratio of 78:15:1:6.

[0093] Comparative Example 6 The difference from Example 1 is that the die pressure in step (5) of the catalyst preparation method is 25 MPa.

[0094] Application Example 1 A simulation experiment was conducted by preparing a high-concentration solution of the new pollutants. The main pollutants and their concentrations were: ibuprofen: 10 mg / L, carbamazepine: 10 mg / L, bisphenol A: 5 mg / L, sulfamethoxazole: 5 mg / L, and ciprofloxacin: 10 mg / L.

[0095] Weigh 0.025 g (0.5 g / L) of each catalyst obtained in Examples 1-3 and Comparative Examples 1-6 respectively, add them to 50 mL of pollutant solutions of a specific concentration, stir thoroughly to mix them evenly, and then carry out the reaction. After the reaction is completed, measure the concentration of pollutants.

[0096] The simulated wastewater was tested for major pollutant indicators. The degradation performance of the iron single-atom catalyst on each pollutant was determined by liquid chromatography (LC-MS / MS). The pollutant test results are shown in Table 1.

[0097] Table 1 Pollutant Indicators

[0098] The results show that the concentration of pollutants in the simulated wastewater was significantly reduced after treatment with the Fenton-like catalyst described in this invention.

[0099] Application Example 2 A simulation experiment was conducted by adding high concentrations of new pollutants to the effluent from the secondary sedimentation tank of a wastewater treatment plant in an industrial park (wastewater from chemical, pharmaceutical, and other industries that has undergone biochemical treatment). The main pollutant indicators were: ibuprofen: 209 μg / L, carbamazepine: 158 μg / L, bisphenol A: 11 μg / L, sulfamethoxazole: 152 μg / L, and ciprofloxacin: 199 μg / L.

[0100] The wastewater purified by the catalysts obtained in Examples 1-3 and Comparative Examples 1-6 was tested for major pollutant indicators. The detection method for the concentration of new pollutants was the same as in Application Example 1, and the test results are shown in Table 2.

[0101] Table 2 Pollutant Indicators .

[0102] The results show that the concentration of pollutants in the simulated secondary sedimentation tank effluent is significantly reduced after treatment with the Fenton-like catalyst described in this invention.

[0103] Based on the above experimental results, it can be seen that the Fenton-like catalyst described in this invention can be used for deep treatment of new pollutant wastewater in a Fenton-like manner, which can efficiently remove various new pollutants from the wastewater and completely get rid of the dependence on exogenous oxidants such as persulfate and ozone. It not only eliminates the risks of chemical reagent storage and transportation and residual toxicity, but also significantly reduces equipment investment and operating energy consumption.

Claims

1. A Fenton-like catalyst, characterized in that, The Fenton-like catalyst is a particulate iron single-atom catalyst with a particle size of 2-3 mm; This granular iron single-atom catalyst The raw materials include: powdered iron single-atom catalyst, modified bentonite, carbon nanofibers and ammonium bicarbonate; wherein, the mass ratio of powdered iron single-atom catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate is (75-80):(13-18):3:

4. The raw materials for the powdered iron single-atom catalyst include 2-methylimidazole, zinc nitrate hexahydrate and iron acetylacetone; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methylimidazole is 1:(5-6):(30-35). The Fenton-like catalyst is prepared by the following steps: (1) Preparation of precursor solution 2-Methylimidazole and zinc nitrate hexahydrate were added to methanol and stirred until homogeneous to obtain a precursor solution; wherein the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole was 1:(5-7), and the mass ratio of zinc nitrate hexahydrate to methanol volume was 1g:(27-30)mL. (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for at least 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:(5-6); The solution of the metal iron organic precursor was centrifuged, the precipitate was collected and dried to obtain the metal iron organic precursor. (3) Preparation of powdered iron single-atom catalyst The metal iron organic precursor obtained in step (2) was placed in a N2 atmosphere and calcined at a constant temperature of 1100-1200℃ for 2-3 hours; after the calcination was completed, it was cooled to room temperature to obtain a powdered iron single-atom catalyst. (4) Preparation of plastic slurry The powdered iron single-atom catalyst obtained in step (3) is mixed with raw material modified bentonite, carbon nanofibers and ammonium bicarbonate in a certain proportion to obtain the total material; deionized water is added to the total material and stirred and plasticized to obtain a uniform plastic slurry. The mass ratio of powdered iron single-atom catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate is (75-80):(13-18):3:4; the amount of deionized water added is 30-35 wt% of the total material mass. (5) Preparation of particulate iron single-atom catalyst The plastic slurry obtained in step (4) is extruded and molded, dried and dehydrated, and then sintered in a N2 atmosphere at 600-650°C. After cooling, granular iron single-atom catalyst is obtained.

2. The Fenton-like catalyst according to claim 1, characterized in that, The raw material powdered iron single-atom catalyst has a porous carbon framework structure, with N element uniformly dispersed in the porous carbon framework, and Fe element forming a spatially correlated Fe-N co-location network with N element.

3. The Fenton-like catalyst according to claim 1, characterized in that, The carbon nanofibers have a diameter of 80-85 nm.

4. The Fenton-like catalyst according to claim 1, characterized in that, The raw material powdered iron single-atom catalyst has a particle size of 1-3 μm.

5. The Fenton-like catalyst according to claim 1, characterized in that, The particulate iron single-atom catalyst has a porosity of 55-65% and a specific surface area of ​​800-1000 m². 2 / g; abrasion index is 1.5-2.5%; compressive strength is 12-18MPa.

6. A method for preparing a Fenton-like catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Preparation of precursor solution 2-Methylimidazole and zinc nitrate hexahydrate were added to methanol and stirred until homogeneous to obtain a precursor solution; wherein the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole was 1:(5-7), and the mass ratio of zinc nitrate hexahydrate to methanol volume was 1g:(27-30)mL. (2) Preparation of organometallic iron precursors Add acetylacetone iron to the precursor solution obtained in step (1) and stir for at least 24 hours to obtain an organic precursor solution of metallic iron; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:(5-6); The solution of the metal iron organic precursor was centrifuged, the precipitate was collected and dried to obtain the metal iron organic precursor. (3) Preparation of powdered iron single-atom catalyst The metal iron organic precursor obtained in step (2) was placed in a N2 atmosphere and calcined at a constant temperature of 1100-1200℃ for 2-3 hours; after the calcination was completed, it was cooled to room temperature to obtain a powdered iron single-atom catalyst. (4) Preparation of plastic slurry The powdered iron single-atom catalyst obtained in step (3) is mixed with raw material modified bentonite, carbon nanofibers and ammonium bicarbonate in a certain proportion to obtain the total material; deionized water is added to the total material and stirred and plasticized to obtain a uniform plastic slurry. The mass ratio of powdered iron single-atom catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate is (75-80):(13-18):3:4; the amount of deionized water added is 30-35 wt% of the total material mass. (5) Preparation of particulate iron single-atom catalyst The plastic slurry obtained in step (4) is extruded and molded, dried and dehydrated, and then sintered in a N2 atmosphere at 600-650°C. After cooling, granular iron single-atom catalyst is obtained.

7. The method for preparing the Fenton-like catalyst according to claim 6, characterized in that, In step (2), the centrifugation rate is 8000 rpm, and the centrifugation is performed 3 times, with each centrifugation lasting 4 minutes. In step (3), the N2 flow rate is 100-150 mL / min; the temperature is increased to 1100-1200℃ at a heating rate of 5℃ / min; and the temperature is cooled to room temperature at a cooling rate of 10℃ / min. In step (5), the extrusion molding is performed using a twin-screw extruder; wherein the rotational speed of the twin screw is 25-30 rpm and the die pressure is 18-20 MPa; In step (5), the air is dried and dehydrated at 100-105℃ for 2-3 hours; the N2 flow rate is 100-150mL / min; the temperature is increased to 600-650℃ at a heating rate of 2℃ / min; and the temperature is controlled and cooled at a cooling rate of 5℃ / min.

8. The application of a Fenton-like catalyst according to any one of claims 1-5 in advanced wastewater treatment, characterized in that, Applicable wastewater contaminants include ibuprofen, sulfamethoxazole, bisphenol A, carbamazepine, or ciprofloxacin.

9. A method for deep treatment of wastewater using a Fenton-like catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: First, Fenton-like catalyst particles are filled into a continuous flow bed reactor to form a Fenton-like catalyst bed with a filling height of 200-300 cm; Subsequently, clean water is injected from the bottom of the continuous fluidized bed reactor at a flow rate of 5-8 m / h to clean the bed. The wastewater requiring advanced treatment can be introduced into a continuous fluidized bed reactor for wastewater treatment. The bottom of the continuous flow bed reactor is equipped with a swirl distributor with a 15° tilt angle. The swirl distributor has an annular array of openings, wherein the opening diameter is 3-4 mm. A layer of alumina ceramic balls with a height of 15-20 cm is laid at the bottom of the continuous flow bed reactor, wherein the particle size of the alumina ceramic balls is 3-5 mm. A stainless steel anti-escape screen with a aperture of 1-2 mm is installed at the top of the continuous flow bed reactor.

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