Granular active carbon supported cobalt-iron bimetallic catalyst and preparation method and application thereof

Abstract

The invention belongs to the technical field of new pollutant sewage treatment, and particularly relates to a granular activated carbon loaded cobalt-iron bimetallic catalyst and a preparation method and application thereof. According to the preparation method, granular active carbon is taken as a carrier, and the granular active carbon loaded cobalt-iron bimetallic catalyst is prepared through an ultrasonic-assisted chemical impregnation-calcination method. The granular activated carbon loaded cobalt-iron bimetallic catalyst can activate peracetic acid to degrade and remove sulfonamide pollutants in water. According to the invention, a FexCo < 3-x > O < 4 > coated granular active carbon / peracetic acid oxidation system is constructed, peracetic acid is activated through cooperation of FexCo < 3-x > O < 4 > bimetal and granular active carbon, free radicals of. OH, CH3C (O) OO and CH3C (O) OO with strong oxidizing property are generated, and deep degradation of sulfonamide pollutants adsorbed in situ is realized. According to the invention, the degradation operation is simple, no toxic by-products are generated, and the disinfection of the culture circulating water is realized while the sulfonamides pollutants in the water are continuously and rapidly removed.

Description

Technical Field

[0001] The invention belongs to the technical field of new pollutant sewage treatment, and specifically relates to a granular activated carbon-loaded cobalt-iron bimetallic catalyst and a preparation method and application thereof. Background Art

[0002] As a new model for rapid transformation and upgrading of aquaculture ponds to achieve zero discharge of pollutants in aquaculture tailwater, the recirculating aquaculture system (RAS) can purify and recycle aquaculture water through a series of water treatment units. During the operation of RAS, when a certain fish disease breaks out in a high-density aquaculture pond, a small amount of approved sulfonamide antibiotics will still be applied. However, these sulfonamide antibiotics cannot be completely metabolized in the fish body, and more than 30% to 80% of the antibiotics will enter the aquaculture water with the urine and feces of the fish. These untreated antibiotics will enter other fish ponds through the circulating water system, polluting the circulating water in the entire system; or they will be discharged into natural water bodies with aquaculture tailwater, which may induce the emergence of antibiotic-resistant microorganisms and the spread of antibiotic resistance genes.

[0003] At present, many researchers have also tried to develop various processes to solve the above problems, such as developing various bioreactors (anaerobic ammonium oxidation, moving bed membrane reactor). However, due to the low C / N ratio (<5) of the circulating water quality and the fast water exchange rate (600-1500L / h), the colonization and growth of microorganisms in various biological treatment units are hindered, making it difficult to effectively remove sulfonamide organic pollutants in the circulating water.

[0004] In recent years, the advanced oxidation process based on peracetic acid (PAA) has attracted widespread attention. PAA has a low OO (159 kJ / mol) bond energy and is easily activated to produce highly reactive ·OH (E 0 =2.73V), CH 3 C(O)O·(E 0 =2.25V) and CH 3 C(O)OO·(E 0 =1.64V) free radicals, which can quickly and efficiently oxidize and degrade sulfonamide antibiotics in water. In addition, PAA, as a peroxide with dual properties (oxidant and disinfectant), has the advantages of low pH dependence, easy implementation (no expensive equipment investment) and no toxic by-products.

[0005] In the advanced oxidation process based on peracetic acid, the generation of free radical species is an important step to achieve water disinfection and oxidative degradation of micropollutants. Free radical species can activate the production of PAA in a variety of ways, such as ultraviolet irradiation, heating or catalysis (transition metals, carbon materials). Among them, the heterogeneous transition metal-based catalysts obtained by existing methods are the most effective activators. However, most of these catalysts are nano-scale powders, and there are problems such as cumbersome preparation steps, low catalyst yield, difficult recovery, easy agglomeration and low reusability. In particular, heterogeneous single metal-based catalysts have low catalytic efficiency, high metal leaching, and secondary pollution in the process of activating PAA. Summary of the invention

[0006] In view of the shortcomings of the above-mentioned prior art, the present invention provides a granular activated carbon-supported cobalt-iron bimetallic catalyst and its preparation method and application. The present invention uses commercially available granular activated carbon as a carrier and adopts an ultrasound-assisted chemical impregnation-calcination method to prepare a granular activated carbon-supported cobalt-iron bimetallic catalyst, namely Fe x Co 3-x O 4 @ Granular activated carbon composite material, x is 1 to 2. The operation steps of the present invention are simple and environmentally friendly, and the granular activated carbon-supported cobalt-iron bimetallic catalyst obtained by the method of the present invention has high catalytic efficiency and low metal leaching amount, thus overcoming the defects of the heterogeneous transition metal-based catalyst in the prior art.

[0007] In order to achieve the above technical objectives, the present invention is implemented through the following technical solutions:

[0008] The present invention provides a method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst, comprising the following steps:

[0009] The commercially available granular activated carbon is pretreated to obtain granular activated carbon with a particle size of 20 to 50 mesh without any impurities through screening, water washing and drying; if the mesh number is too small, the specific surface area of ​​the granular activated carbon is small, the contact area with sewage is small, and the adsorption capacity is weak; if the mesh number is too high, the particle size of the granular activated carbon is small, it is not easy to settle and it will increase the resistance to water flow.

[0010] A soluble iron salt and a soluble cobalt salt are mixed together in ultrapure water to obtain a metal salt solution.

[0011] The cleaned granular activated carbon is added to the metal salt solution, and the metal salt solution is evenly impregnated into the surface of the granular activated carbon by applying ultrasound. Then, it is dried and calcined in a muffle furnace, and then washed and dried to remove the metal oxides not fixed on the surface of the granular activated carbon to obtain Fe x Co 3-x O 4@Granular activated carbon composite material, x is 1-2, and the catalytic effect is best when x is 1; that is, the granular activated carbon supports the cobalt-iron bimetallic catalyst.

[0012] Furthermore, the commercially available granular activated carbon is selected from coal-made charcoal, fruit shell charcoal or coconut shell charcoal, and coal-made charcoal is preferred.

[0013] Furthermore, the ratio of the molar amount of iron in the soluble iron salt to the molar amount of cobalt in the soluble cobalt salt is x:3-x, where x is 1 to 2; the soluble iron salt is selected from ferric chloride, ferric nitrate or ferric sulfate; and the soluble cobalt salt is selected from cobalt chloride, cobalt nitrate or cobalt sulfate.

[0014] Furthermore, the ultrasonic frequency is 20kHz to 40kHz, and the time is 0.25h to 0.5h. Preferably, the ultrasonic wave is performed at 40kHz for 0.5h. If the frequency and time are lower than this range, it will be difficult for the metal salt solution to be evenly impregnated on the surface of the granular activated carbon; if the frequency and time are higher than this range, part of the granular activated carbon will be broken.

[0015] Furthermore, the calcination temperature in the muffle furnace is 300° C. to 400° C., the calcination time is 1.5 h to 2 h, and the heating rate is 5° C. / min. Preferably, the calcination is performed at 400° C. for 2 h.

[0016] The present invention also protects a granular activated carbon-supported cobalt-iron bimetallic catalyst prepared by the above-mentioned preparation method, wherein the granular activated carbon-supported cobalt-iron bimetallic catalyst is Fe x Co 3-x O 4 Composite materials with granular activated carbon, Fe x Co 3-x O 4 Stably compounded on the surface of granular activated carbon.

[0017] Furthermore, in the granular activated carbon-supported cobalt-iron bimetallic catalyst, Fe x Co 3-x O 4 The mass ratio of Fe to granular activated carbon is 0.2 to 5:100. This mass ratio is obtained through experiments and increases with the increase of Fe x Co 3-x O 4 The degradation performance of sulfonamide pollutants increases with the increase of the added amount.

[0018] The present invention also protects the application of granular activated carbon supported cobalt-iron bimetallic catalyst in removing sulfonamide pollutants. The removal method is: mixing granular activated carbon supported cobalt-iron bimetallic catalyst, peracetic acid and sulfonamide pollutants, and carrying out an oxidative degradation reaction of the sulfonamide pollutants; the sulfonamide pollutants are selected from one or more of sulfamethoxazole, sulfadiazine, sulfamethoxazole and sulfadimethoxine.

[0019] Furthermore, Fe x Co 3-x O 4 @The granular activated carbon composite material is loaded into the reactor, and then a mixture of sulfonamide pollutants and peracetic acid is used as the influent. The pH value of the mixture is 6-7. The mixture is transported to the reactor to realize a continuous flow oxidation degradation reaction in the reactor to remove sulfonamide pollutants in the water.

[0020] The fixed bed reactor includes a mixing tank, a reactor and a collecting tank. The reactor is connected between the mixing tank and the collecting tank, and a peristaltic pump is arranged between the reactor and the mixing tank. The reactor is uniformly filled with Fe x Co 3-x O 4 @ Granular activated carbon composite material; a mixed solution of sulfonamide pollutants and peracetic acid is stored in the mixing tank. The water inlet direction of the mixed solution is from bottom to top, the peristaltic pump flow rate is 0.5mL / min, and the hydraulic retention time is 15min~20min; the concentration ratio of peracetic acid to sulfonamide pollutants is 0.05mmol / L:5μmol / L~30μmol / L.

[0021] Furthermore, Fe x Co 3-x O 4 @The granular activated carbon composite material was added to the aqueous solution of sulfonamide pollutants with a pH of 6.0 to 7.0, mechanically stirred, and Fe x Co 3-x O 4 @ Granular activated carbon composite material adsorbs sulfonamide pollutants, and then adds peracetic acid solution to carry out oxidative degradation reaction to remove sulfonamide pollutants in water. x Co 3-x O 4 @The ratio of the dosage of granular activated carbon composite material, the concentration of sulfonamide pollutants and the concentration of peracetic acid is 0.1g / L~0.5g / L: 30μmol / L: 0.05mmol / L~0.5mmol / L. 2 O 4 @The dosage of granular activated carbon composite material is 0.4g / L, and the concentration of peracetic acid is 0.1mmol / L.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention uses commercially available granular activated carbon (GAC) as a carrier, immerses the granular activated carbon into a metal salt solution containing a soluble iron salt and a soluble cobalt salt, and prepares a granular activated carbon-supported cobalt-iron bimetallic catalyst by an ultrasonic-assisted chemical impregnation-calcination method. The granular activated carbon-supported cobalt-iron bimetallic catalyst is Fe x Co 3-x O 4 @ Granular activated carbon composite material. The preparation method of the present invention has simple operation steps, is environmentally friendly, has low cost, and can realize large-scale synthesis of supported catalyst Fe x Co 3-x O 4 @Granular activated carbon composite materials.

[0024] In the present invention, cobalt, iron bimetallic and granular activated carbon are introduced to synergistically activate peracetic acid to generate OH, CH 3 C(O)O· and CH 3 C(O)OO· free radicals, through the adsorption of sulfonamide pollutants by granular activated carbon, achieve in-situ efficient oxidation degradation of sulfonamide pollutants. At pH 6.0-7.0, the degradation rate of sulfonamide pollutants in water is as high as 97%. In addition, due to the bonding effect of the strong metal bond between Co-Fe, the leaching amount of Co and Fe is significantly reduced. x Co 3-x O 4 Loaded onto the surface of granular activated carbon, solid-liquid separation can be achieved through natural gravity sedimentation; it can also be achieved through Fe x Co 3-x O 4 The inherent magnetism of the product uses magnetic separation to enhance the separation and recovery efficiency.

[0025] Fe prepared by the method of the present invention x Co 3-x O 4 @ Granular activated carbon composite materials also have the advantages of being difficult to agglomerate and highly reusable. The reason for this is that the mutual repulsion of electrostatic forces between granular activated carbons offsets part of the magnetic Fe x Co 3-x O 4 The attraction between the materials makes Fe x Co 3-x O 4 @Granular activated carbon composite materials have good dispersibility.

[0026] 2. The present invention constructs Fe for the first time x Co 3-x O 4@ Granular activated carbon composite material / peracetic acid oxidation system, activates peracetic acid with dual properties (oxidant and disinfectant) to degrade and remove sulfonamide pollutants in water, through Fe x Co 3-x O 4 Bimetallic and granular activated carbon synergistically activate peracetic acid to produce strong oxidizing ·OH and CH 3 C(O)OO· and CH 3 C(O)O·free radicals can achieve deep degradation of sulfonamide pollutants adsorbed in situ.

[0027] 3. The present invention also proposes to prepare a fixed bed reactor, add a mixed solution of sulfonamide pollutants and peracetic acid as influent, and utilize Fe x Co 3-x O 4 @ Granular activated carbon composite material is used as filler to achieve degradation of sulfonamide pollutants under continuous flow operation. x Co 3-x O 4 @The degradation of sulfonamide pollutants by granular activated carbon composite materials is simple to operate, and no toxic byproducts are generated. While continuously and rapidly removing sulfonamide pollutants in water, it also achieves the disinfection of aquaculture circulating water. In addition, the system has the advantages of high catalytic efficiency, strong ability to oxidatively degrade sulfonamide pollutants, easy catalyst recovery, and low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 GAC, calcined GAC at 400°C, FeCo 2 O 4 and 5%-FeCo of Example 1 2 O 4 / SEM image of GAC.

[0029] Figure 2 For granular activated carbon, 5%-FeCo 2 O 4 / GAC and 1%-FeCo of Example 2 2 O 4 / GAC real photos.

[0030] Figure 3 5%-FeCo of Example 1 2 O 4 / GAC scanning electron microscope image and solid-liquid separation effect diagram.

[0031] Figure 4It is a comparison chart of the degradation effects of sulfamethoxazole on granular activated carbon, granular activated carbon loaded with cobalt-iron bimetallic catalyst of Examples 1 to 5, and calcined granular activated carbon of Comparative Example 1.

[0032] Figure 5 The 5%-FeCo 2 O 4 / Comparison of the degradation effects of sulfamethoxazole by GAC after 4 cycles of experiments.

[0033] Figure 6 The 5%-FeCo 2 O 4 Figure 3. Co and Fe ion leaching amounts of GAC after 4 cycle experiments.

[0034] Figure 7 Schematic diagram of the structure of a fixed bed reactor.

[0035] Description of reference numerals:

[0036] 1-Mixing tank; 2-Reactor; 3-Collection tank; 4-Peristaltic pump. DETAILED DESCRIPTION

[0037] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are conventional methods unless otherwise specified.

[0038] The Fe prepared by the present invention x Co 3-x O 4 @ Granular activated carbon composite materials can continuously activate peracetic acid and have a high degradation efficiency for sulfonamide pollutants. Taking sulfamethoxazole as an example, at 25°C and a solution pH of 7.0, only 40 mg of catalyst FeCo 2 O 4 @ Granular activated carbon composite material and 0.1mmol / L peracetic acid, the degradation rate of 100mL, 30μmol / L sulfamethoxazole reached 97% within 45min. 2 O 4 The synergistic mechanism between the activated carbon and the granular activated carbon showed that the removal rate of sulfamethoxazole was still above 94% after four cycles of degradation. The leaching amount of cobalt ions and iron ions was low after the cyclic degradation, which showed good reusability and stability and reduced secondary pollution.2 O 4 The magnetic effect can realize rapid solid-liquid separation and overcome the technical defects of the heterogeneous transition metal-based catalysts in the prior art.

[0039] The technical solution of the present invention is further explained by using embodiments and comparative examples, as shown below:

[0040] Example 1

[0041] A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst comprises the following steps:

[0042] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0043] S2, 0.8484g of Fe(NO 3 ) 3 9H 2 O and 1.2222 g of Co(NO 3)2 6H 2 O were dissolved in 30 mL of ultrapure water, and then 10 g of the clean activated carbon prepared in step S1 was added thereto, followed by ultrasonic cleaning at 20 kHz and ultrasonic dispersion for 30 min to obtain a suspension.

[0044] S3. Pour the suspension of step S2 into a glass culture dish so that the solvent just covers the clean activated carbon, then place it in a 60°C oven to dry for 4 hours, and then place it in a muffle furnace at 400°C to calcine for 2 hours. The heating rate of the muffle furnace calcination is 5°C / min to obtain an intermediate.

[0045] S4, washing the intermediate of step S3 with water to remove the metal oxides not loaded on the surface of the clean activated carbon, and then drying in an oven at 60°C to constant weight to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst, wherein the granular activated carbon-loaded cobalt-iron bimetallic catalyst is FeCo 2 O 4 @Granular activated carbon composites, FeCo 2 O 4 The mass ratio of FeCo to clean activated carbon is 0.5:10, recorded as 5%-FeCo 2 O 4 / GAC.

[0046] Example 2

[0047] A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst, which is the same as the preparation steps of Example 1, except that the Fe(NO 3 )3 9H 2 O and Co(NO 3)2 6H 2 The addition amount of O comprises the following steps:

[0048] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0049] S2, 0.1697g of Fe(NO 3 ) 3 9H 2 O and 0.2446 g of Co(NO 3)2 6H 2 O were dissolved in 30 mL of ultrapure water, and then 10 g of the clean activated carbon prepared in step S1 was added thereto, followed by ultrasonic cleaning at 20 kHz and ultrasonic dispersion for 30 min to obtain a suspension.

[0050] S3. Pour the suspension of step S2 into a glass culture dish so that the solvent just covers the clean activated carbon, then place it in a 60°C oven to dry for 4 hours, and then place it in a muffle furnace at 400°C to calcine for 2 hours. The heating rate of the muffle furnace calcination is 5°C / min to obtain an intermediate.

[0051] S4, washing the intermediate of step S3 with water to remove the metal oxides not loaded on the surface of the clean activated carbon, and then drying in an oven at 60°C to constant weight to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst, wherein the granular activated carbon-loaded cobalt-iron bimetallic catalyst is FeCo 2 O 4 @Granular activated carbon composites, FeCo 2 O 4 The mass ratio of FeCo to clean activated carbon is 0.1:10, recorded as 1%-FeCo 2 O 4 / GAC.

[0052] Example 3

[0053] A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst, which is the same as the preparation steps of Example 1, except that the Fe(NO 3 ) 3 9H 2 O and Co(NO 3)2 6H 2 The addition amount of O comprises the following steps:

[0054] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0055] S2, 0.0849g of Fe(NO 3 ) 3 9H 2 O and 0.1223 g of Co(NO 3)2 6H 2 O were dissolved in 30 mL of ultrapure water, and then 10 g of the clean activated carbon prepared in step S1 was added thereto, followed by ultrasonic cleaning at 20 kHz and ultrasonic dispersion for 30 min to obtain a suspension.

[0056] S3. Pour the suspension of step S2 into a glass culture dish so that the solvent just covers the clean activated carbon, then place it in a 60°C oven to dry for 4 hours, and then place it in a muffle furnace at 400°C to calcine for 2 hours. The heating rate of the muffle furnace calcination is 5°C / min to obtain an intermediate.

[0057] S4, washing the intermediate of step S3 with water to remove the metal oxides not loaded on the surface of the clean activated carbon, and then drying in an oven at 60°C to constant weight to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst, wherein the granular activated carbon-loaded cobalt-iron bimetallic catalyst is FeCo 2 O 4 @Granular activated carbon composites, FeCo 2 O 4 The mass ratio of FeCo to clean activated carbon is 0.05:10, recorded as 0.5%-FeCo 2 O 4 / GAC.

[0058] Example 4

[0059] A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst, which is the same as the preparation steps of Example 1, except that the Fe(NO 3 ) 3 9H 2 O and Co(NO 3)2 6H 2 The addition amount of O comprises the following steps:

[0060] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0061] S2, 0.0339g of Fe(NO 3 ) 39H 2 O and 0.0489 g of Co(NO 3)2 6H 2 O were dissolved in 30 mL of ultrapure water, and then 10 g of the clean activated carbon prepared in step S1 was added thereto, followed by ultrasonic cleaning at 20 kHz and ultrasonic dispersion for 30 min to obtain a suspension.

[0062] S3. Pour the suspension of step S2 into a glass culture dish so that the solvent just covers the clean activated carbon, then place it in a 60°C oven to dry for 4 hours, and then place it in a muffle furnace at 400°C to calcine for 2 hours. The heating rate of the muffle furnace calcination is 5°C / min to obtain an intermediate.

[0063] S4, washing the intermediate of step S3 with water to remove the metal oxides not loaded on the surface of the clean activated carbon, and then drying in an oven at 60°C to constant weight to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst, wherein the granular activated carbon-loaded cobalt-iron bimetallic catalyst is FeCo 2 O 4 @Granular activated carbon composites, FeCo 2 O 4 The mass ratio of FeCo to clean activated carbon is 0.02:10, recorded as 0.2%-FeCo 2 O 4 / GAC.

[0064] Example 5

[0065] A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst, which is the same as the preparation steps of Example 1, except that the Fe(NO 3 ) 3 9H 2 O and Co(NO 3)2 6H 2 The addition amount of O comprises the following steps:

[0066] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0067] S2, 0.0170g of Fe(NO 3 ) 3 9H 2 O and 0.0245 g of Co(NO 3)2 6H 2 O were dissolved in 30 mL of ultrapure water, and then 10 g of the clean activated carbon prepared in step S1 was added thereto, followed by ultrasonic cleaning at 20 kHz and ultrasonic dispersion for 30 min to obtain a suspension.

[0068] S3. Pour the suspension of step S2 into a glass culture dish so that the solvent just covers the clean activated carbon, then place it in a 60°C oven to dry for 4 hours, and then place it in a muffle furnace at 400°C to calcine for 2 hours. The heating rate of the muffle furnace calcination is 5°C / min to obtain an intermediate.

[0069] S4, washing the intermediate of step S3 with water to remove the metal oxides not loaded on the surface of the clean activated carbon, and then drying in an oven at 60°C to constant weight to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst, wherein the granular activated carbon-loaded cobalt-iron bimetallic catalyst is FeCo 2 O 4 @Granular activated carbon composites, FeCo 2 O 4 The mass ratio of FeCo to clean activated carbon is 0.01:10, recorded as 0.1%-FeCo 2 O 4 / GAC.

[0070] Example 6

[0071] A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst comprises the following steps:

[0072] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0073] S2, 1.2812g of Fe(NO 3 ) 3 9H 2 O and 0.9229 g of Co(NO 3)2 6H 2 O were dissolved in 30 mL of ultrapure water, and then 10 g of the clean activated carbon from step S1 was added thereto, and then placed in a 30 kHz ultrasonic cleaning and ultrasonically dispersed for 20 min to obtain a suspension.

[0074] S3. Pour the suspension of step S2 into a glass culture dish so that the solvent just covers the clean activated carbon, then place it in a 60°C oven to dry for 4 hours, and then place it in a muffle furnace at 350°C to calcine for 1.5 hours. The heating rate of the muffle furnace calcination is 5°C / min to obtain an intermediate.

[0075] S4, washing the intermediate of step S3 with water to remove the metal oxides not loaded on the surface of the clean activated carbon, and then drying in an oven at 60°C to constant weight to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst, wherein the granular activated carbon-loaded cobalt-iron bimetallic catalyst is 5%-Fe 1.5 Co1.5 O 4 @Granular activated carbon composite materials.

[0076] Example 7

[0077] A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst comprises the following steps:

[0078] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0079] S2, 1.7191g of Fe(NO 3 ) 3 9H 2 O and 0.6192 g of Co(NO 3)2 6H 2 O were dissolved in 30 mL of ultrapure water, and then 10 g of the clean activated carbon from step S1 was added thereto, and then placed in a 40 kHz ultrasonic cleaning and ultrasonically dispersed for 15 min to obtain a suspension.

[0080] S3. Pour the suspension of step S2 into a glass culture dish so that the solvent just covers the clean activated carbon, then place it in a 60°C oven to dry for 4 hours, and then place it in a muffle furnace at 300°C to calcine for 2 hours. The heating rate of the muffle furnace calcination is 5°C / min to obtain an intermediate.

[0081] S4, washing the intermediate of step S3 with water to remove the metal oxides not loaded on the surface of the clean activated carbon, and then drying in an oven at 60°C to constant weight to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst, wherein the granular activated carbon-loaded cobalt-iron bimetallic catalyst is 5%-Fe 2 CoO 4 @Granular activated carbon composite materials.

[0082] Comparative Example 1

[0083] The method for preparing calcined granular activated carbon comprises the following steps:

[0084] S1. Wash the commercially available coal-based granular activated carbon (particle size 20-50 mesh) with ultrapure water to remove the powdered carbon on the surface, then place it in an oven at 60°C for 12 hours and cool it to obtain clean activated carbon for later use.

[0085] S2. The clean activated carbon from step S1 is placed in a muffle furnace at 400° C. and calcined for 2 h. The heating rate of the muffle furnace calcination is 5° C. / min to obtain calcined granular activated carbon, which is recorded as GAC-400° C.

[0086] Examples 1 to 7 of the present invention all produce granular activated carbon-supported cobalt-iron bimetallic catalysts with excellent catalytic performance. The following is a study using the granular activated carbon-supported cobalt-iron bimetallic catalysts of Examples 1 to 5 as examples. The specific research methods and results are as follows:

[0087] like Figure 1 As shown in the SEM spectrum, it is clear that the spherical FeCo 2 O 4 The particles are loaded onto the surface of the granular activated carbon. Figure 2 It shows that the surface of granular activated carbon is loaded with FeCo 2 O 4 The sample photo after the successful loading of FeCo 2 O 4 The surface of the granular activated carbon is light brown. Figure 3 The 5%-FeCo prepared in Example 1 is also shown. 2 O 4 / GAC is magnetic and can be recovered by magnetic separation.

[0088] Next, the performance verification of activated peracetic acid in degrading sulfamethoxazole was carried out. The specific experimental method was as follows: the temperature was maintained at 25±2°C in a constant temperature water bath, firstly, 40 mg of FeCo of Examples 1 to 5 were weighed using an analytical balance. 2 O 4 @ Granular activated carbon composite material, calcined granular activated carbon of comparative example 1 and granular activated carbon of example 1 were placed in 7 different 150mL beakers, and then 100mL, 30μmol / L sulfamethoxazole (SMX) was added to each beaker, and then 10mmol / L phosphate buffer solution was added to maintain the solution pH at 7, and mechanical stirring was performed for 20min to complete the adsorption of SMX at a speed of 150r / min. 0.1mmol / L PAA solution was added to start the reaction, and 1mL was sampled within a preset time (0min, 2min, 5min, 10min, 20min, 30min, 45min), filtered with a 0.45μm water filter membrane, and added to a liquid phase vial containing 20μL, 1mol / L sodium thiosulfate to terminate the reaction, and the remaining SMX concentration in the solution was determined using a high performance liquid chromatograph.

[0089] The results are as follows Figure 4 As shown, from Figure 4It can be seen that after 45 minutes of reaction, GAC removed about 26% of SMX, indicating that GAC itself can activate PAA. After heat treatment at 400℃ (GAC-400℃), the activation performance of GAC was further improved, and the SMX removal rate reached 37%. In addition, the activation performance of granular activated carbon loaded with cobalt-iron bimetallic catalysts with different doping ratios was compared, and it was found that with the increase of FeCo 2 O 4 As the doping amount increases, the removal efficiency of SMX by granular activated carbon supported cobalt-iron bimetallic catalyst also increases gradually, among which 5%-FeCo 2 O 4 / GAC exhibited the best SMX removal efficiency, reaching 97%.

[0090] The following is the 5%-FeCo 2 O 4 / GAC was used as an example to conduct an experiment on the cyclic degradation of SMX by the PAA oxidation system. The specific experimental method was as follows: the temperature was maintained at 25±2°C in a constant temperature water bath, and 40 mg of 5%-FeCo in Example 1 was first weighed using an analytical balance. 2 O 4 / GAC, placed in a 150mL beaker, then added 100mL, 30μmol / L SMX to the beaker, and then added 10mmol / L phosphate buffer solution to maintain the solution pH at 7, mechanically stirred for 20min to complete the adsorption of SMX, the speed was 150r / min. Add 0.1mmol / L PAA solution to start the reaction, and take 1mL of sample within the preset time (0min, 2min, 5min, 10min, 20min, 30min, 45min), filter with 0.45μm water filter membrane, and add to the liquid phase vial containing 20μL, 1mol / L sodium thiosulfate to terminate the reaction, and use high performance liquid chromatography to determine the remaining SMX concentration in the solution.

[0091] Recycling 5%-FeCo 2 O 4 / GAC: After the degradation experiment, stop the mechanical stirring and let it stand for 2 minutes, then place the magnet at the bottom of the beaker, pour off the reaction solution, wash it three times with ultrapure water, and dry it in an oven at 60°C. Repeat the above steps for 4 times to evaluate the degradation of 5%-FeCo 2 O 4 / GAC's stability and reusability.

[0092] The results are as follows Figure 5 and Figure 6 As shown, 5%-FeCo 2 O 4In the fourth cycle degradation experiment, GAC can still remove 94% of SMX. In addition, in the four cycles of degradation experiments, the leaching amount of cobalt ions is less than 8.5μg / L, and the leaching amount of iron ions is less than 2.3μg / L. This shows that 5%-FeCo 2 O 4 / GAC has good reusability and stability.

[0093] Figure 7 It is a structural schematic diagram of a fixed bed reactor designed based on the technical solution of the present invention. Based on the fixed bed reactor, granular activated carbon-supported cobalt-iron bimetallic catalyst can be used to industrially degrade sulfonamide pollutants.

[0094] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention, and the protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst, characterized in that: The steps include: The granular activated carbon is added to a metal salt solution containing a soluble iron salt and a soluble cobalt salt, and the metal salt solution is evenly impregnated into the surface of the granular activated carbon with the assistance of ultrasound. The granular activated carbon is then dried, calcined, washed with water to remove the metal oxides not fixed on the surface of the granular activated carbon, and dried to obtain a granular activated carbon-loaded cobalt-iron bimetallic catalyst.

2. The method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst according to claim 1, characterized in that: The ratio of the molar amount of iron in the soluble iron salt to the molar amount of cobalt in the soluble cobalt salt is x:3-x, where x is 1-2.

3. The method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst according to claim 1, characterized in that: The ultrasonic conditions are: ultrasonication at 20kHz to 40kHz for 0.25h to 0.5h.

4. The method for preparing a granular activated carbon-supported cobalt-iron bimetallic catalyst according to claim 1, characterized in that: The calcination conditions are: calcination at 300°C to 400°C for 1.5h to 3h.

5. A granular activated carbon-supported cobalt-iron bimetallic catalyst prepared by the preparation method according to any one of claims 1 to 4.

6. The granular activated carbon-supported cobalt-iron bimetallic catalyst according to claim 5, characterized in that: In the granular activated carbon-loaded cobalt-iron bimetallic catalyst, the cobalt-iron bimetallic is loaded on the surface of the granular activated carbon, and the mass ratio of the cobalt-iron bimetallic to the granular activated carbon is 0.2 to 5:

100.

7. Use of the granular activated carbon supported cobalt-iron bimetallic catalyst according to claim 5 in removing sulfonamide pollutants, characterized in that: The removal method is: mixing granular activated carbon loaded with a cobalt-iron bimetallic catalyst, peracetic acid and sulfonamide pollutants to carry out an oxidative degradation reaction of the sulfonamide pollutants; Among them, the sulfonamide pollutants are selected from one or more of sulfamethoxazole, sulfadiazine, sulfamethoxazole, and sulfadimethoxine.

8. The use according to claim 7, characterized in that: The granular activated carbon-supported cobalt-iron bimetallic catalyst is loaded into a fixed bed reactor, and then a mixed solution of sulfonamide pollutants and peracetic acid is added, the pH of the mixed solution is 6-7, and a continuous flow oxidation degradation reaction is performed to remove sulfonamide pollutants in water; The fixed bed reactor comprises a mixing tank (1), a reactor (2) and a collecting tank (3), wherein the reactor (2) is connected between the mixing tank (1) and the collecting tank (3), and a peristaltic pump (4) is arranged between the reactor (2) and the mixing tank (1); The reactor (2) is uniformly filled with granular activated carbon-supported cobalt-iron bimetallic catalyst; The mixing tank (1) stores a mixed solution of sulfonamide pollutants and peracetic acid.

9. The use according to claim 8, characterized in that: The peristaltic pump (4) has a flow rate of 0.5 mL / min and a hydraulic retention time of 15 to 20 min.

10. The use according to claim 7, characterized in that: The granular activated carbon-loaded cobalt-iron bimetallic catalyst is added to an aqueous solution of sulfonamide pollutants at a pH of 6-7. After mechanical stirring and adsorption, a peracetic acid solution is added to perform an oxidative degradation reaction to remove the sulfonamide pollutants in the water.

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