A fenton-like catalyst, and a preparation method and application thereof

Abstract

The application belongs to the technical field of wastewater treatment, and particularly relates to a Fenton-like catalyst, a preparation method and application thereof. The Fenton-like catalyst is a granular iron monatomic catalyst. Raw materials include a powdered 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 powdered iron monatomic catalyst; (4) preparing a plastic slurry; and (5) preparing a granular iron monatomic catalyst. The Fenton-like catalyst can be used for advanced treatment of sewage, and can efficiently degrade various new pollutants without additional oxidants.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wastewater treatment, and particularly relates to a Fenton-like catalyst, a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of pharmaceutical, chemical and other industries, a large amount of newly synthesized antibiotics is discharged into the water environment through wastewater. As a typical new pollutant, antibiotics can persist in the water environment for a long time and continuously enrich due to their high chemical stability and anti-biodegradation characteristics. At the same time, their strong biological toxicity not only directly endangers the population structure of aquatic organisms, but also induces cumulative health risks such as gene mutation in the human body through the food chain. However, due to the difficulty of conventional water treatment processes in effectively removing new pollutants such as antibiotics, the safety of drinking water and the stability of the ecological system are continuously threatened, which has become a serious challenge in current water pollution control.

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

[0004] The purpose of the present application is to provide a Fenton-like catalyst, a preparation method and application thereof in view of the defects of current Fenton-like systems relying on high-concentration peroxides. The Fenton-like catalyst is used for the advanced treatment of wastewater, and various new pollutants can be efficiently degraded without additional oxidants.

[0005] The preparation of the Fenton-like catalyst according to the present application first precisely prepares an iron-based organic precursor through in-situ coordination polymerization, and then a powder-like iron monatomic catalyst is prepared through high-temperature pyrolysis. The powder-like iron monatomic catalyst is mixed with modified bentonite, carbon nanofibers and ammonium bicarbonate, extruded and sintered to obtain a granular iron monatomic catalyst.

[0006] The technical scheme of the present application is as follows:

[0007] A Fenton-like catalyst is a granular iron monatomic catalyst with a particle size of 2-3 mm. The granular iron monatomic catalyst comprises the following raw materials: powder-like iron monatomic catalyst, modified bentonite, carbon nanofibers and ammonium bicarbonate. The mass ratio of the powder-like iron monatomic catalyst, modified bentonite, carbon nanofibers and ammonium bicarbonate is (75-80):(13-18):3:4.

[0008] The raw materials of the powder-like iron single-atom catalyst include 2-methyl imidazole, zinc nitrate hexahydrate and iron acetylacetone; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methyl imidazole is 1: (5-6): (30-35).

[0009] The Fenton-like catalyst is prepared by the following steps:

[0010] (1) Preparation of precursor solution

[0011] 2-methyl imidazole and zinc nitrate hexahydrate are added to methanol and stirred uniformly to prepare a precursor solution; wherein the molar ratio of zinc nitrate hexahydrate: 2-methyl imidazole is 1: (5-7), and the ratio of the mass of zinc nitrate hexahydrate to the volume of methanol is 1 g: (27-30) mL.

[0012] (2) Preparation of metal iron organic precursor

[0013] Iron acetylacetone is added to the precursor solution obtained in step (1) and stirred for at least 24 h to obtain a metal iron organic precursor solution; wherein the molar ratio of iron acetylacetone: zinc nitrate hexahydrate is 1: (5-6).

[0014] The metal iron organic precursor solution is centrifuged, and the precipitate is collected and dried to prepare a metal iron organic precursor.

[0015] (3) Preparation of powder-like iron single-atom catalyst

[0016] The metal iron organic precursor obtained in step (2) is placed in an N2 atmosphere and calcined at a constant temperature of 1100-1200℃ for 2-3 h; after calcination, it is cooled to room temperature; to obtain a powder-like iron single-atom catalyst.

[0017] (4) Preparation of plastic slurry

[0018] The powder-like iron single-atom catalyst obtained in step (3) is mixed with raw material modified bentonite, carbon nanofiber and ammonium bicarbonate in a certain proportion to obtain total materials; deionized water is added to the total materials and stirred to plasticize to prepare a uniform plastic slurry.

[0019] The mass ratio of the powder-like iron single-atom catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is (75-80): (13-18): 3: 4; the amount of deionized water added is 30-35 wt% of the mass of the total materials.

[0020] (5) Preparation of granular iron single-atom catalyst

[0021] The plastic slurry prepared in step (4) is extruded and molded, dried and dehydrated, and then sintered at 600-650℃ in an N2 atmosphere, and cooled to obtain a granular iron single-atom catalyst.

[0022] In the application, the raw material of the Fenton-like catalyst, the powdered iron monatomic catalyst, has a porous carbon skeleton structure, N elements are uniformly dispersed in the porous carbon skeleton, and Fe elements form a spatially associated Fe-N co-localization network with N elements.

[0023] The powdered iron monatomic catalyst has a porous carbon skeleton structure, a clean surface without visible particulate matter, and only amorphous carbon strips exist in the carbon carrier, completely lacking the characteristic lattice of iron, iron oxide or iron carbide nanoparticles. In addition, N elements are uniformly dispersed in the carbon skeleton, and Fe elements are highly overlapped with nitrogen in an atomic dispersion mode, forming a spatially associated Fe-N co-localization network. As can be seen, the iron in the powdered iron monatomic catalyst is anchored to the nitrogen site by chemical bonding, and there is no local aggregation phenomenon, while the carbon skeleton structure remains intact.

[0024] In the application, the diameter of the carbon nanofiber, the raw material of the Fenton-like catalyst, is 80-85 nm.

[0025] In the application, the particle size of the powdered iron monatomic catalyst, the raw material of the Fenton-like catalyst, is 1-3 μm.

[0026] In the application, the porosity of the granular iron monatomic catalyst is 55-65%; the specific surface area is 800-1000 m 2 / g; the abrasion index is 1.5-2.5%; and the compressive strength is 12-18 MPa.

[0027] A preparation method of the Fenton-like catalyst, comprising the following steps:

[0028] (1) Preparation of precursor solution

[0029] 2-methylimidazole and zinc nitrate hexahydrate are added to methanol, stirred uniformly, and a precursor solution is prepared. The molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:(5-7), and the mass ratio of zinc nitrate hexahydrate to the volume of methanol is 1g:(27-30)mL.

[0030] (2) Preparation of metal iron organic precursor

[0031] Acetylacetone iron is added to the precursor solution obtained in step (1), stirred for at least 24 h, and a metal iron organic precursor solution is obtained; the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:(5-6);

[0032] The metal iron organic precursor solution is centrifuged, the precipitate is collected and dried, and the metal iron organic precursor is prepared.

[0033] (3) Preparation of powdered iron monatomic catalyst

[0034] The metal iron organic precursor obtained in step (2) is placed in an N2 atmosphere, and is calcined at 1100-1200 DEG C for 2-3 h; after calcination, the temperature is cooled to room temperature; and a powder-like iron monatomic catalyst is obtained.

[0035] (4) Preparation of plastic slurry

[0036] The powder-like iron monatomic catalyst obtained in step (3) is mixed with raw material modified bentonite (Al2O3*4SiO2), carbon nanofiber and pore-forming agent ammonium bicarbonate in a certain proportion to obtain total material; deionized water is added to the total material, and stirring plasticization is carried out to obtain a uniform plastic slurry.

[0037] The mass ratio of the powder-like iron monatomic catalyst, modified bentonite, carbon nanofiber and ammonium bicarbonate is (75-80):(13-18):3:4; and the amount of deionized water added is 30-35 wt% of the total material.

[0038] (5) Preparation of granular iron monatomic catalyst

[0039] The plastic slurry prepared in step (4) is extruded and formed, and after drying and dehydration, sintering treatment is carried out at 600-650 DEG C for 2-3 h in an N2 atmosphere, and after cooling, a granular iron monatomic catalyst with regular size is obtained.

[0040] In the application, in step (2) of the preparation method of the Fenton-like catalyst, the centrifugation rate is 8000 rpm, and centrifugation is carried out 3 times, with each centrifugation time being 4 min; and the precipitate is rinsed with ethanol during centrifugation.

[0041] In the application, in step (3) of the preparation method of the Fenton-like catalyst, the N2 flow rate is 100-150 mL / min; the temperature is raised to 1100-1200 DEG C at a temperature raising rate of 5 DEG C / min; and the temperature is cooled to room temperature at a temperature lowering rate of 10 DEG C / min.

[0042] In the application, in step (5) of the preparation method of the Fenton-like catalyst, the extrusion molding adopts a double-screw extruder; the rotation speed of the double screw is 25-30 rpm, and the die pressure is 18-20 MPa.

[0043] In the application, in step (5) of the preparation method of the Fenton-like catalyst, air drying and dehydration are carried out at 100-105 DEG C for 2-3 h; the N2 flow rate is 100-150 mL / min; the temperature is raised to 600-650 DEG C at a temperature raising rate of 2 DEG C / min; and temperature control cooling is carried out at a temperature lowering rate of 5 DEG C / min.

[0044] The application of the above Fenton-like catalyst in advanced wastewater treatment (especially new pollutant wastewater). The applicable wastewater pollutants (new pollutants) include ibuprofen (PCM), sulfamethoxazole (SMZ), bisphenol A (BPA), carbamazepine (CBZ), ciprofloxacin (CIP), etc.

[0045] A method for advanced wastewater treatment by using the above Fenton-like catalyst, comprising the following steps:

[0046] First, the Fenton-like catalyst particles are filled into the continuous flow bed reactor to form a Fenton-like catalyst bed with a filling height of 200-300 cm.

[0047] Subsequently, the clean water is injected from the bottom end of the continuous flow bed reactor at a flow rate of 5-8 m / h, and the uniform accumulation of the Fenton-like catalyst bed is realized by the synergistic effect of hydraulic load and material settlement, and the bed is cleaned.

[0048] The wastewater to be treated is introduced into the continuous flow bed reactor for wastewater treatment.

[0049] The bottom of the continuous flow bed reactor is provided with a cyclone distributor with an inclination angle of 15°, and the cyclone distributor has an annular array of holes with a hole diameter of 3-4 mm.

[0050] An alumina ceramic ball layer with a height of 15-20 cm is laid at the bottom of the continuous flow bed reactor, and the particle size of the alumina ceramic ball is 3-5 mm to realize water flow pre-distribution.

[0051] A stainless steel anti-escape screen with a hole diameter of 1-2 mm is arranged at the top of the continuous flow bed reactor.

[0052] The continuous flow bed reactor has three functions of water flow pre-distribution, prevention of filler expansion, and prevention of filler loss, and can sustainably operate the catalytic reaction, comprehensively treat the effluent after biochemical treatment, avoid the construction demand of a multi-stage advanced treatment system, and significantly reduce the construction cost of wastewater advanced treatment facilities.

[0053] The Fenton-like catalyst in combination with the continuous flow catalytic reactor can efficiently treat the effluent after biochemical treatment and realize the long-term stable removal of new pollutants. In addition, the low sludge production can also help to reduce the burden of chemical sludge treatment and disposal.

[0054] The Fenton-like catalyst has a precise coordination structure, and a double reaction center with an electron-poor / electron-rich microzone structure is formed on the surface thereof; pollutants in biochemical wastewater are adsorbed on the electron-poor region as an electron donor and transfer electrons, and the electrons are transferred to the electron-rich region through the bond bridge on the surface of the catalyst; the single iron atom in the Fenton-like catalyst can efficiently capture the electrons from the pollutants, thereby realizing efficient and selective degradation of new pollutants under the condition of no addition of oxidants. The process completely eliminates the dependence on external oxidants such as persulfate and ozone in the traditional process, not only eliminating the storage and transportation risks and residual toxicity of chemical reagents, but also significantly reducing equipment investment and energy consumption. In complex water quality (such as a high-chloride ion and carbonate system), the electron transfer mechanism can avoid the free radical quenching effect, maintain excellent degradation efficiency, and the iron valence state cycle (Fe 2+ / Fe 3+ ) driven by dissolved oxygen enables the catalyst to have self-regeneration capability.

[0055] Compared with the traditional reactor, the continuous flow bed reactor has the advantages of high mass transfer efficiency, strong pollution resistance (avoiding catalyst passivation), low energy consumption, and the like, and can realize deep degradation of new pollutants in a short residence time, and has excellent new pollutant degradation rate, thereby providing an efficient and reliable path for the engineering treatment of highly toxic new pollutants.

[0056] In the continuous flow bed reactor, the Fenton-like catalyst can realize efficient and sustainable removal of pollutants through its unique dynamic mass transfer and electron coordination mechanism, and can tolerate water quality fluctuations. When the water containing pollutants flows through the reactor, the turbulent flow forces the pollutant molecules to be preferentially adsorbed on the surface of the catalyst and to transfer electrons, and at this time, the single iron atom as the core electron acceptor efficiently captures the electrons to realize long-term stable removal of the pollutants. At the same time, the continuous operation characteristics of the flow bed promote the dynamic regeneration of the catalyst, and the degradation products are washed away from the active sites in real time, and the oxygen reduction reaction continuously repairs the oxidation state of the catalytic site, thereby forming a self-cycle. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 It is a transmission electron microscope image of the powder-like single iron atom catalyst at 200 nm.

[0058] Figure 2 It is a transmission electron microscope image of the powder-like single iron atom catalyst at 5 nm.

[0059] Figure 3 It is an energy spectrum distribution diagram of the powder-like single iron atom catalyst.

[0060] Figure 4 It is a schematic diagram of the method for Fenton-like deep treatment of new pollutants in wastewater according to the application. DETAILED DESCRIPTION

[0061] The technical solutions of the present application are described in detail below.

[0062] The specific steps of the method for deep treatment of wastewater by using the Fenton-like catalyst are as follows:

[0063] First, the Fenton-like catalyst particles are filled into the continuous flow bed reactor to form a Fenton-like catalyst bed with a filling height of 200 cm.

[0064] Subsequently, the clean water is injected from the bottom end of the continuous flow bed reactor at a flow rate of 8 m / h, so that the Fenton-like catalyst bed is uniformly stacked and the bed is cleaned.

[0065] The wastewater to be deep treated is introduced into the continuous flow bed reactor for wastewater treatment.

[0066] The bottom of the continuous flow bed reactor is provided with a cyclone distributor with an inclination angle of 15°, and the cyclone distributor has an annular array of holes with a hole diameter of 4 mm.

[0067] An alumina ceramic ball layer with a height of 15 cm is laid at the bottom of the continuous flow bed reactor, and the particle size of the alumina ceramic balls is 3 mm.

[0068] A stainless steel anti-escape screen with a pore size of 1 mm is provided at the top of the continuous flow bed reactor.

[0069] Example 1

[0070] The Fenton-like catalyst is a granular iron monatomic catalyst, and the raw materials are as follows: powdered iron monatomic catalyst, modified bentonite, carbon nanofiber with a diameter of 80 nm, and ammonium bicarbonate; wherein the mass ratio of powdered iron monatomic catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is 78:15:3:4.

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

[0072] The preparation method of the Fenton-like catalyst includes the following specific steps:

[0073] (1) Preparation of precursor solution

[0074] Zinc nitrate hexahydrate and 2-methyl imidazole are added to methanol in a molar ratio of 1:5, and stirred uniformly to prepare a precursor solution; wherein the mass ratio of zinc nitrate hexahydrate to the volume of methanol is 1:27 g / mL.

[0075] (2) Preparation of metal iron organic precursor

[0076] The acetylacetone iron is added into the precursor solution obtained in step (1) and stirred for 24 h to obtain a metal iron organic precursor solution; wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:6.

[0077] The metal iron organic precursor solution is centrifuged, and the precipitate is collected and dried to obtain the metal iron organic precursor; wherein the centrifugal rate is 8000 rpm, the centrifugal time is 4 min each time, and ethanol is used to rinse the precipitate during the centrifugal process.

[0078] (3) Preparation of powder iron monatomic catalyst

[0079] The metal iron organic precursor obtained in step (2) is placed in a N2 atmosphere, heated to 1100℃ at a heating rate of 5℃ / min, and then kept at constant temperature for 2 h; after the calcination is completed, it is cooled to room temperature at a cooling rate of 10℃ / min; to obtain a powder iron monatomic catalyst; wherein the N2 flow rate is 100 mL / min.

[0080] (4) Preparation of plastic slurry

[0081] The powder iron monatomic catalyst obtained in step (3) is mixed with raw material modified bentonite (Al2O3·4SiO2), carbon nanofiber and pore-forming agent ammonium bicarbonate in proportion to obtain the total material; deionized water is added to the total material, and stirring and plasticizing are performed to obtain a uniform plastic slurry.

[0082] The mass ratio of the powder iron monatomic catalyst, the modified bentonite, the carbon nanofiber and the ammonium bicarbonate is 78:15:3:4; the amount of deionized water added is 35wt% of the mass of the total material.

[0083] (5) Preparation of granular iron monatomic catalyst

[0084] The plastic slurry prepared in step (4) is extruded into granules by a double screw extruder; wherein the rotation speed of the double screw is 25 rpm, and the die pressure is 18 MPa.

[0085] After air drying and dehydration at 105℃ for 3 h, sintering treatment is carried out at 600℃ for 2 h in a N2 atmosphere at a heating rate of 2℃ / min; after cooling at a cooling rate of 5℃ / min, a granular iron monatomic catalyst with a size of 2 mm is obtained. The N2 flow rate is 100 mL / min.

[0086] Example 2

[0087] The Fenton-like catalyst is a granular iron monatomic catalyst, and the raw materials are as follows: a powder iron monatomic catalyst, modified bentonite, carbon nanofibers, and ammonium bicarbonate; wherein the mass ratio of the powder iron monatomic catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate is 75:18:3:4.

[0088] The raw materials of the powder iron monatomic 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.

[0089] The preparation method of the Fenton-like catalyst, and the specific steps are as follows:

[0090] (1) Preparation of precursor solution

[0091] Zinc nitrate hexahydrate and 2-methylimidazole are added to methanol in a molar ratio of 1:7, and stirred uniformly to prepare a precursor solution; wherein the mass ratio of zinc nitrate hexahydrate to the volume of methanol is 1:30 g / mL.

[0092] (2) Preparation of metal iron organic precursor

[0093] Iron acetylacetone is added to the precursor solution obtained in step (1), and stirred for 24 h to obtain a metal iron organic precursor solution; wherein the molar ratio of iron acetylacetone to zinc nitrate hexahydrate is 1:5.

[0094] The metal iron organic precursor solution is centrifuged, and the precipitate is collected and dried to prepare a metal iron organic precursor; wherein the centrifugal speed is 8000 rpm, and the centrifugation time is 4 min each time, and ethanol is used to rinse the precipitate during the centrifugation process.

[0095] (3) Preparation of powder iron monatomic catalyst

[0096] The metal iron organic precursor obtained in step (2) is placed in a N2 atmosphere, and heated to 1200℃ at a heating rate of 5℃ / min, and then calcined for 2h; after the calcination is completed, it is cooled to room temperature at a cooling rate of 10℃ / min; to obtain a powder iron monatomic catalyst; wherein the N2 flow rate is 150 mL / min.

[0097] (4) Preparation of plastic slurry

[0098] The powder iron monatomic catalyst obtained in step (3) and the raw materials modified bentonite (Al2O3·4SiO2), carbon nanofibers, and pore-forming agent ammonium bicarbonate are mixed in proportion to obtain total materials; deionized water is added to the total materials, and stirred and plasticized to prepare a uniform plastic slurry.

[0099] The mass ratio of the powder-like iron single-atom catalyst, modified bentonite, carbon nanofiber and ammonium bicarbonate is 75:18:3:4; and the amount of the deionized water added is 30wt% of the total material mass.

[0100] (5) Preparation of the granular iron single-atom catalyst

[0101] The plastic slurry prepared in step (4) is extruded into granular form by using a double-screw extruder, wherein the rotation speed of the double screw is 30 rpm and the die pressure is 20 MPa.

[0102] After air drying and dehydration at 105℃ for 3h, the sintering treatment is performed by heating the sample to 650℃ at a heating rate of 2℃ / min under N2 atmosphere, and then cooling at a cooling rate of 5℃ / min to obtain the granular iron single-atom catalyst with a regular size of 3mm. The N2 flow rate is 150mL / min.

[0103] Example 3

[0104] The Fenton-like catalyst is a granular iron single-atom catalyst, and the raw materials thereof include powder-like iron single-atom catalyst, modified bentonite, carbon nanofiber and ammonium bicarbonate; and the mass ratio of the powder-like iron single-atom catalyst, modified bentonite, carbon nanofiber and ammonium bicarbonate is 80:13:3:4.

[0105] The raw materials of the powder-like iron single-atom catalyst include 2-methyl imidazole, zinc nitrate hexahydrate and iron acetylacetone; and the molar ratio of iron acetylacetone, zinc nitrate hexahydrate and 2-methyl imidazole is 1:6:30.

[0106] The preparation method of the Fenton-like catalyst includes the following specific steps:

[0107] (1) Preparation of the precursor solution

[0108] The zinc nitrate hexahydrate and 2-methyl imidazole are added to methanol in a molar ratio of 1:5, and stirred uniformly to obtain the precursor solution; and the mass ratio of the zinc nitrate hexahydrate to the volume of methanol is 1:27g / mL.

[0109] (2) Preparation of the metal iron organic precursor

[0110] The iron acetylacetone is added to the precursor solution obtained in step (1), and stirred for 24h to obtain the metal iron organic precursor solution; and the molar ratio of the iron acetylacetone to the zinc nitrate hexahydrate is 1:6.

[0111] The metal iron organic precursor solution is centrifuged, and the precipitate is collected and dried to obtain the metal iron organic precursor; and the centrifugal speed is 8000rpm, and the centrifugal time is 4min for each of the three times, and the precipitate is rinsed with ethanol during the centrifugation.

[0112] (3) Preparation of powdered iron monatomic catalyst

[0113] The metal iron organic precursor obtained in step (2) is placed in a N2 atmosphere, heated to 1100°C at a heating rate of 5°C / min, and held at constant temperature for 2h. After the calcination is completed, it is cooled to room temperature at a cooling rate of 10°C / min. A powdered iron monatomic catalyst is obtained. The N2 flow rate is 100 mL / min.

[0114] (4) Preparation of plastic slurry

[0115] The powdered iron monatomic catalyst obtained in step (3) is mixed with raw material modified bentonite (Al2O3·4SiO2), carbon nanofiber 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 to plasticize to obtain a uniform plastic slurry.

[0116] The mass ratio of powdered iron monatomic catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is 80:13:3:4. The amount of deionized water added is 35wt% of the total material.

[0117] (5) Preparation of granular iron monatomic catalyst

[0118] The plastic slurry prepared in step (4) is extruded into granules using a double screw extruder, wherein the rotation speed of the double screw is 25 rpm and the die pressure is 18 MPa.

[0119] After air drying and dehydrating at 105°C for 3h, the granular iron monatomic catalyst with a regular size of 2mm is prepared by sintering treatment in a N2 atmosphere at a heating rate of 2°C / min to 600°C, and cooling at a cooling rate of 5°C / min. The N2 flow rate is 100 mL / min.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Example 1 is that the catalyst of this comparative example is a powdered iron monatomic 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.

[0122] The preparation method of the catalyst is as follows:

[0123] (1) Preparation of precursor solution

[0124] The precursor solution was prepared by adding zinc nitrate hexahydrate and 2-methylimidazole in a molar ratio of 1:5 into methanol and stirring uniformly, wherein the mass ratio of zinc nitrate hexahydrate to the volume of methanol was 1:27 g / mL.

[0125] (2) Preparation of metal iron organic precursor

[0126] The metal iron organic precursor solution was obtained by adding acetylacetone iron into the precursor solution obtained in step (1) and stirring for 24 h, wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate was 1:6.

[0127] The metal iron organic precursor was prepared by centrifuging the metal iron organic precursor solution, collecting the precipitate and drying, wherein the centrifugation rate was 8000 rpm, the centrifugation time was 4 min each time, and ethanol was used to rinse the precipitate during the centrifugation process.

[0128] (3) Preparation of powder iron monatomic catalyst

[0129] The metal iron organic precursor obtained in step (2) was placed in a N2 atmosphere, heated to 1100℃ at a heating rate of 5℃ / min, and then kept at a constant temperature for 2 h; after the calcination was completed, the temperature was cooled to room temperature at a cooling rate of 10℃ / min; a powder iron monatomic catalyst was obtained; wherein the N2 flow rate was 100 mL / min.

[0130] Comparative Example 2

[0131] The difference from Example 1 is that it does not contain carbon nanofibers.

[0132] The granular iron monatomic catalyst of this comparative example has the following raw materials: powder iron monatomic catalyst, modified bentonite and ammonium bicarbonate; wherein the mass ratio of powder iron monatomic catalyst: modified bentonite: ammonium bicarbonate is 78:18:4.

[0133] The preparation method of the catalyst is as follows:

[0134] The total material was obtained by mixing the obtained powder iron monatomic catalyst with raw materials modified bentonite (Al2O3·4SiO2) and pore-forming agent ammonium bicarbonate in proportion; deionized water was added to the total material, and the mixture was stirred and plasticized to obtain a uniform plastic slurry.

[0135] The mass ratio of powder iron monatomic catalyst: modified bentonite: ammonium bicarbonate is 78:18:4.

[0136] The other is the same as Example 1.

[0137] Comparative Example 3

[0138] Different from example 1, the granular iron single-atom catalyst of the comparative example is prepared from the following raw materials: the mass ratio of the powdered iron single-atom catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is 70:23:3:4.

[0139] Comparative example 4

[0140] Different from example 1, the granular iron single-atom catalyst of the comparative example is prepared from the following raw materials: the mass ratio of the powdered iron single-atom catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is 85:8:3:4.

[0141] Comparative example 5

[0142] Different from example 1, the granular iron single-atom catalyst of the comparative example is prepared from the following raw materials: the mass ratio of the powdered iron single-atom catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is 78:15:1:6.

[0143] Comparative example 6

[0144] Different from example 1, the die pressure in step (5) of the catalyst preparation method is 25 MPa.

[0145] Application example 1

[0146] A simulation experiment is performed by configuring a high-concentration new pollutant solution, and the main pollutants and concentrations are as follows: ibuprofen: 10 mg / L, carbamazepine: 10 mg / L, bisphenol A: 5 mg / L, sulfamethoxazole: 5 mg / L, and ciprofloxacin: 10 mg / L.

[0147] 0.025 g (0.5 g / L) of each catalyst obtained in examples 1-3 and comparative examples 1-6 is respectively added to 50 mL of the pollutant solution with a specific concentration, and is fully stirred to uniformly mix, and then is subjected to reaction, and the concentration of the pollutant is measured after the reaction is completed.

[0148] The main pollutant indicators of the prepared simulation wastewater are detected, the degradation performance of the iron single-atom catalyst on each pollutant is determined by liquid chromatography (LC-MS / MS), and the pollutant detection results are shown in Table 1.

[0149] Table 1 Pollutant indicators

[0150]

[0151] The results show that the concentration of the pollutant in the simulation wastewater is significantly reduced after being treated by the Fenton-like catalyst.

[0152] Application example 2

[0153] The simulated experiment is carried out by adding high-concentration new pollutants to the effluent of the secondary sedimentation tank of a sewage treatment plant in an industrial park (the effluent after biochemical treatment of chemical, pharmaceutical and other wastewater), and the main pollutant indexes are: ibuprofen: 209 μg / L, carbamazepine: 158 μg / L, bisphenol A: 11 μg / L, sulfamethoxazole: 152 μg / L, and ciprofloxacin: 199 μg / L.

[0154] The main pollutant indexes of the treated wastewater treated by each catalyst obtained in Examples 1-3 and Comparative Examples 1-6 are detected. The detection method of the concentration of new pollutants is referred to Application Example 1, and the detection results are shown in Table 2.

[0155] Table 2 Pollutant indexes

[0156] .

[0157] The results show that the concentration of pollutants in the simulated effluent of the secondary sedimentation tank is significantly reduced after being treated by the Fenton-like catalyst.

[0158] Based on the above test results, it can be seen that the Fenton-like catalyst can be used for Fenton-like advanced treatment of new pollutant wastewater, can efficiently remove various new pollutants in the wastewater, and completely eliminates the dependence on exogenous oxidants such as persulfate and ozone, not only eliminates the storage and transportation risks and residual toxicity of chemical agents, but also significantly reduces the equipment investment and operation energy consumption.

Claims

1. A Fenton-like catalyst characterized in that, The Fenton-like catalyst is a granular iron monatomic catalyst with a particle size of 2-3 mm. The granular iron monatomic catalyst The raw material of the powder iron monatomic catalyst comprises 2-methylimidazole, zinc nitrate hexahydrate, and iron acetylacetone; the molar ratio of iron acetylacetone: zinc nitrate hexahydrate: 2-methylimidazole is 1: (5-6): (30-35). The raw material of the powder iron monatomic catalyst comprises 2-methylimidazole, zinc nitrate hexahydrate, and iron acetylacetone; 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 are added to methanol and stirred uniformly to prepare a precursor solution; the molar ratio of zinc nitrate hexahydrate: 2-methylimidazole is 1: (5-7), and the mass ratio of zinc nitrate hexahydrate to the volume of methanol is 1 g: (27-30) mL; (2) Preparation of metal iron organic precursor Iron acetylacetone is added to the precursor solution obtained in step (1) and stirred for at least 24 h to obtain a metal iron organic precursor solution; the molar ratio of iron acetylacetone: zinc nitrate hexahydrate is 1: (5-6); The metal iron organic precursor solution is centrifuged, the precipitate is collected and dried to prepare a metal iron organic precursor; (3) Preparation of powder iron monatomic catalyst The metal iron organic precursor obtained in step (2) is placed in an N2 atmosphere and calcined at 1100-1200°C for 2-3 h; after calcination, it is cooled to room temperature; a powder iron monatomic catalyst is obtained; (4) Preparation of plastic slurry The powder iron monatomic catalyst obtained in step (3) is mixed with raw materials of modified bentonite, carbon nanofibers, and ammonium bicarbonate in a certain proportion to obtain total materials; deionized water is added to the total materials and stirred to plasticize to prepare a uniform plastic slurry; The mass ratio of the powder iron monatomic catalyst: modified bentonite: carbon nanofibers: ammonium bicarbonate is (75-80): (13-18): 3: 4; the amount of deionized water added is 30-35 wt% of the mass of the total materials; (5) Preparation of granular iron monatomic catalyst The plastic slurry prepared in step (4) is extruded and molded, dried and dehydrated, and then sintered at 600-650°C in an N2 atmosphere to obtain a granular iron monatomic catalyst.

2. The Fenton-like catalyst according to claim 1, characterized in that, The raw material powder iron monatomic catalyst has a porous carbon skeleton structure, and N elements are uniformly dispersed in the porous carbon skeleton, and Fe elements form a spatially associated Fe-N co-localization network with N elements.

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

4. The Fenton-like catalyst according to claim 1, characterized in that, The particle size of the raw material powder iron monatomic catalyst is 1-3 μm.

5. The Fenton-like catalyst according to claim 1, wherein The granular iron single-atom catalyst has a porosity of 55-65%, a specific surface area of 800-1000 m 2 / g; an abrasion index of 1.5-2.5%; and a compressive strength of 12-18 MPa.

6. A method of preparing a Fenton's-like catalyst according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: (1) Preparation of precursor solution A precursor solution is prepared by adding 2-methylimidazole and zinc nitrate hexahydrate into methanol and stirring uniformly, wherein the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:(5-7), and the mass ratio of zinc nitrate hexahydrate to methanol is 1g:(27-30)mL; (2) Preparation of metal iron organic precursor The precursor solution obtained in step (1) is added with acetylacetone iron and stirred for at least 24 hours to obtain a metal iron organic precursor solution, wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:(5-6); The metal iron organic precursor solution is centrifuged, and the precipitate is collected and dried to obtain a metal iron organic precursor; (3) Preparation of powder iron monatomic catalyst The metal iron organic precursor obtained in step (2) is placed in a N2 atmosphere and calcined at 1100-1200℃ for 2-3 hours; after calcination, it is cooled to room temperature; a powder iron monatomic catalyst is obtained; (4) Preparation of plastic slurry The powder iron monatomic catalyst obtained in step (3) is mixed with raw material modified bentonite, carbon nanofiber and ammonium bicarbonate in a certain proportion to obtain total material; deionized water is added to the total material and stirred to plasticize to obtain a uniform plastic slurry; wherein the mass ratio of powder iron monatomic catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is (75-80):(13-18):3:4; the amount of deionized water added is 30-35wt% of the total material; (5) Preparation of granular iron monatomic catalyst The plastic slurry prepared in step (4) is extruded and formed, and after drying and dehydration, sintering treatment is carried out in a N2 atmosphere at 600-650℃, and after cooling, a granular iron monatomic catalyst is obtained.

7. The method of preparing a Fenton's-like catalyst according to claim 6, characterized in that, In step (2), the centrifugal speed is 8000rpm, and the centrifugation is carried out 3 times, each time for 4min; In step (3), the N2 flow rate is 100-150mL / min; the temperature is raised to 1100-1200℃ at a rate of 5℃ / min; and the temperature is cooled to room temperature at a rate of 10℃ / min; In step (5), the extrusion molding is carried out by using a double screw extruder; wherein the rotation speed of the double screw is 25-30rpm, and the die pressure is 18-20MPa; In step (5), air drying and dehydration are carried out at 100-105℃ for 2-3h; the N2 flow rate is 100-150mL / min; the temperature is raised to 600-650℃ at a rate of 2℃ / min; and the temperature is cooled at a rate of 5℃ / min.

8. Use of the Fenton-like catalyst according to any one of claims 1 to 5 for the advanced treatment of wastewater, characterized in that, The suitable sewage pollutants include ibuprofen, sulfamethoxazole, bisphenol A, carbamazepine or ciprofloxacin.

9. A method for advanced treatment of wastewater using the Fenton-like catalyst according to any one of claims 1-5, characterized in that, The method comprises the following steps: First, the Fenton-like catalyst particles are filled into a continuous flow bed reactor to form a Fenton-like catalyst bed with a filling height of 200-300cm; Then, the clean water is injected from the bottom end of the continuous flow bed reactor at a flow rate of 5-8m / h to clean the bed; The sewage to be treated is introduced into the continuous flow bed reactor for sewage treatment. A precursor solution is prepared by adding 2-methylimidazole and zinc nitrate hexahydrate into methanol and stirring uniformly, wherein the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:(5-7), and the mass ratio of zinc nitrate hexahydrate to methanol is 1g:(27-30)mL; (2) Preparation of metal iron organic precursor The precursor solution obtained in step (1) is added with acetylacetone iron and stirred for at least 24 hours to obtain a metal iron organic precursor solution, wherein the molar ratio of acetylacetone iron to zinc nitrate hexahydrate is 1:(5-6); The metal iron organic precursor solution is centrifuged, and the precipitate is collected and dried to obtain a metal iron organic precursor; (3) Preparation of powder iron monatomic catalyst The metal iron organic precursor obtained in step (2) is placed in a N2 atmosphere and calcined at 1100-1200℃ for 2-3 hours; after calcination, it is cooled to room temperature; a powder iron monatomic catalyst is obtained; (4) Preparation of plastic slurry The powder iron monatomic catalyst obtained in step (3) is mixed with raw material modified bentonite, carbon nanofiber and ammonium bicarbonate in a certain proportion to obtain total material; deionized water is added to the total material and stirred to plasticize to obtain a uniform plastic slurry; wherein the mass ratio of powder iron monatomic catalyst: modified bentonite: carbon nanofiber: ammonium bicarbonate is (75-80):(13-18):3:4; the amount of deionized water added is 30-35wt% of the total material; (5) Preparation of granular iron monatomic catalyst The plastic slurry prepared in step (4) is extruded and formed, and after drying and dehydration, sintering treatment is carried out in a N2 atmosphere at 600-650℃, and after cooling, a granular iron monatomic catalyst is obtained. The suitable sewage pollutants include ibuprofen, sulfamethoxazole, bisphenol A, carbamazepine or ciprofloxacin. including the following steps: First, the Fenton-like catalyst particles are filled into a continuous flow bed reactor to form a Fenton-like catalyst bed with a filling height of 200-300cm; Then, the clean water is injected from the bottom end of the continuous flow bed reactor at a flow rate of 5-8m / h to clean the bed; The sewage to be treated is introduced into the continuous flow bed reactor for sewage treatment. The bottom of the continuous flow bed reactor is configured with a cyclone distributor with a 15° inclination angle, which has an annular array of openings with a diameter of 3-4 mm; The bottom of the continuous flow bed reactor is configured with a cyclone distributor with a 15° inclination angle, which has an annular array of openings with a diameter of 3-4 mm; The top of the continuous flow bed reactor is provided with a stainless steel escape-proof screen with a pore size of 1-2 mm.

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