Double transition metal doped carbon material as well as preparation method and application thereof

Abstract

The invention discloses a double-transition-metal-doped carbon material and a preparation method and application thereof.The double-transition-metal-doped carbon material is obtained through dipping-pyrolysis with forestry and agricultural residues as raw materials and transition metal salts such as Fe and Mn, Co, Ni and Cu as modification reagents, and the transition metal salts specifically comprise Fe-Mn / C, Fe-Co / C, Fe-Ni / C, Fe-Cu / C and the like. Transition metal in the double-transition-metal-doped carbon material exists in the form of diatoms (Fe-X, X = Mn, Co, Ni or Cu), Fe is a first transition metal, X is a second transition metal, and X is a third transition metal. The prepared double-transition-metal-doped carbon material can activate peroxymonosulfate (PMS) to generate multiple high-activity oxides, and the high-activity oxides have a good oxidative degradation effect on antibiotics such as tetracycline in a water body. The catalytic activity of the double-transition-metal-doped carbon material is higher than that of an undoped carbon material, and the double-transition-metal-doped carbon material can be used as a potential water treatment functional material.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon materials, and in particular to a double transition metal doped carbon material and a preparation method and application thereof. Background Art

[0003] Traditional flocculation, precipitation, adsorption and other methods can effectively remove high-concentration macromolecular organic matter and inorganic salt ions in water, but have no obvious effect on trace and trace residual small molecular organic pollutants (antibiotics, etc.). Methods such as membrane filtration are too expensive. Carbon-based materials can be used as adsorption and catalytic materials to purify trace antibiotics in water, but the stable C=C saturated structure of the original carbon material is not conducive to the circulation of electrons in its structure, thereby limiting its catalytic activity in activating peroxymonosulfate (PMS). The single-atom carbon-based catalyst prepared by "impregnation-pyrolysis" of transition metals has a significant coordination structure, which can accelerate the circulation of electrons in the local microenvironment of carbon-based materials and thus has higher catalytic activity in Fenton-like reactions based on peroxymonosulfate. However, this peroxymonosulfate-based Fenton-like reaction usually involves multiple steps such as activation, stabilization, and accumulation, and it is difficult to break the inherent scale relationship of adsorption energy at single-atom sites. Therefore, it is also urgent to continue to develop carbon-based catalysts with stronger catalytic activity. Summary of the invention

[0004] The purpose of the present invention is to provide a double transition metal doped carbon material and its preparation method and application, so as to solve the problem that the above carbon material has insufficient purification effect on antibiotics. In view of the above problem, the present invention constructs a double atomic catalyst on the basis of a single atomic carbon-based catalyst, breaks the scale and spatial limitations of adsorption energy on a single atomic site, realizes the multi-step reaction synergistic effect of double transition metal atom coupling, and optimizes the adsorption process and energy barrier of the intermediate product, which can greatly improve the reaction kinetics and catalytic activity.

[0005] To achieve the above object, the first aspect of the present invention provides a method for preparing a double transition metal doped carbon material, comprising the following steps: Step 1: Preparation of wood fiber powder Using agricultural and forestry waste as raw materials, wood fiber powder is obtained through drying, crushing and sieving in sequence; Step 2: Doping The wood fiber powder is placed in a reactor, an iron salt solution is added, and the mixture is stirred evenly, and then a transition metal salt is added, and the mixture is stirred evenly to ensure that the iron salt and the transition metal salt are fully dispersed and absorbed by the wood fiber powder to obtain a mixed suspension; Step 3: Pyrolysis The mixed suspension was placed in an oven for drying, and then transferred to a tubular furnace for pyrolysis under a N2 atmosphere, cooled to room temperature, and then alternately washed with clean water and anhydrous ethanol and dried to obtain a double transition metal doped carbon material.

[0006] Preferably, in step 1, 50-100 mesh wood fiber powder is obtained by sieving.

[0007] Preferably, the agricultural and forestry waste in step 1 is one of agricultural waste and forestry waste, the agricultural waste is at least one of bagasse, straw, rice husk, fruit peel, and fruit shell, and the forestry waste is at least one of pine, fir, and mulberry residues.

[0008] Preferably, in step 2, the iron salt is ferric chloride hexahydrate, and the transition metal salt is one of manganese chloride tetrahydrate, cobalt chloride hexahydrate, copper sulfate pentahydrate and nickel chloride hexahydrate.

[0009] Preferably, in step 2, the total mass of the iron salt and the transition metal salt is 1‰-5‰ of the wood fiber powder, and the molar ratio of the iron salt to the transition metal salt is 1:5-5:1.

[0010] Preferably, the concentration of the iron salt in step 2 is 180-220 mg / L.

[0011] Preferably, in step 3, the calcination temperature in the tubular furnace is 400-1000° C. and the calcination time is 1-5 h.

[0012] Preferably, the drying temperature in step 3 is 60-80° C. and the drying time is 1-24 h.

[0013] The second aspect of the present invention provides a double transition metal doped carbon material, which is prepared by the above-mentioned preparation method.

[0014] A third aspect of the present invention provides an application of a double transition metal doped carbon material in the degradation of antibiotics.

[0015] Therefore, the present invention adopts a double transition metal doped carbon material with the above structure and its preparation method and application, which have the following beneficial effects: (1) The double transition metal doped in the present invention exists in the form of single atoms and has stronger catalytic activity than the original carbon material. Specifically, after the activated PMS, it has faster degradation kinetics and stronger degradation efficiency for antibiotics such as tetracycline.

[0016] (2) The degradation rate of tetracycline by the Fe-Co / C composite material prepared by the present invention can reach about 99% in about 180 min. Its excellent catalytic activity mainly comes from the doping of Fe and Co double transition metals. Compared with the undoped original carbon material, the doping of transition metals makes Fe-N x 、Co-Nx The co-doping of Fe-Co double transition metals can not only form a special Fe-N x -Co coordination bond, Fe atoms also provide additional electrons to adjacent Co atoms, promoting the d The band shifts, thereby optimizing the adsorption of PMS and rapidly generating highly active oxides through a low energy barrier pathway, accelerating the oxidative degradation of antibiotics in water.

[0017] (3) The Fe-Co / C composite material prepared in the present invention is a universal water pollution treatment material and has a good purification effect on a variety of antibiotics in water.

[0018] (4) The double transition metal doped carbon material prepared by the present invention uses agricultural and forestry waste fibers as raw materials, and has many advantages such as simple process, saving raw materials, low cost, and excellent effect. At the same time, using agricultural and forestry waste fibers as carbon sources has the advantages of turning waste into treasure and recycling waste resources, avoiding the addition of excessive chemical raw materials.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FTIR graphs of materials prepared in Examples 1-4 and Comparative Example 1; Figure 2 XRD patterns of materials prepared in Examples 1-4 and Comparative Example 1; Figure 3 Raman spectra of materials prepared in Examples 1-4 and Comparative Example 1; Figure 4 (a) is the SEM image of Fe-Co / C material; Figure 4 (b) is the TEM image of Fe-Co / C material; Figure 4 (c) is a high-angle annular dark field scanning transmission electron microscope photo of the Fe-Co / C material; Figure 5 This is the X-ray electron spectrum of Fe-Co / C material; Figure 6 (a) shows the effects of the materials prepared in Examples 1-4 and Comparative Example 1 on the degradation kinetics of tetracycline when the dosage of PMS is 10 mg; Figure 6 (b) shows the effects of the materials prepared in Examples 1-4 and Comparative Example 1 on the degradation kinetics of tetracycline when the dosage of PMS is 20 mg; Figure 6 (c) shows the effects of the materials prepared in Examples 1-4 and Comparative Example 1 on the degradation kinetics of tetracycline when the dosage of PMS is 30 mg; Figure 7The effect of Fe-Co / C dosage on the degradation kinetics of tetracycline; Figure 8 The effect of pH on the degradation kinetics of tetracycline by Fe-Co / C materials; Fig. 9 The degradation efficiency of Fe-Co / C activated PMS on different types of antibiotics. DETAILED DESCRIPTION

[0021] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and a specific operation process, but the present invention is not limited to this embodiment. Example 1

[0022] A method for preparing a double transition metal doped carbon material Fe-Mn / C comprises the following steps: Step 1: Preparation of wood fiber powder The waste mulberry branches are used as raw materials, dried in an oven, crushed in a grinder, and then sieved (50-100 meshes) to obtain wood fiber powder.

[0023] Step 2: Preparation of transition metal doped suspension Weigh 2 g of the above-obtained wood fiber powder and place it in a beaker. Add 10 mL of 200 mg / L ferric chloride hexahydrate (transition metal one) and disperse it evenly by magnetic stirring. Then add 1.5 mg of manganese chloride tetrahydrate (transition metal two) and continue stirring until it is uniform. The stirring time is not less than 6 hours to ensure that the iron salt and manganese salt are fully dispersed and absorbed by the wood powder.

[0024] Step 3: Preparation of double transition metal-doped carbon materials The suspension was placed in an oven at 60 °C for drying, and then transferred to a crucible in a tubular furnace. It was pyrolyzed at 800 °C for 2 h in a N2 atmosphere. After cooling to room temperature, Fe and Mn co-doped carbon material (Fe-Mn / C) was obtained. Example 2

[0025] A method for preparing a double transition metal doped carbon material Fe-Co / C, which is different from Example 1 in that the transition metal II added in step 2 is 1.8 mg of cobalt chloride hexahydrate. Example 3

[0026] A method for preparing a double transition metal doped carbon material Fe-Cu / C, which is different from Example 1 in that the transition metal II added in step 2 is 1.9 mg of copper sulfate pentahydrate. Example 4

[0027] A method for preparing a double transition metal doped carbon material Fe-Ni / C, which is different from Example 1 in that the second transition metal added in step 2 is 1.8 mg of nickel chloride hexahydrate.

[0028] Comparative Example 1 A method for preparing a carbon material, which differs from Example 1 in that step 2 is omitted and iron salt and transition metal salt are not added.

[0029] Comparative Example 2 A method for preparing a transition metal-doped carbon material Fe / C, which differs from Example 1 in that no transition metal salt is added in step 2.

[0030] Comparative Example 3 A method for preparing a transition metal-doped carbon material Co / C, which differs from Example 2 in that no iron salt is added in step 2.

[0031] Comparative Example 4 A method for preparing a double transition metal doped carbon material Fe-Al / C, which differs from Example 2 in that the cobalt chloride hexahydrate added in step 2 is replaced by an equimolar amount of aluminum chloride.

[0032] Test Example 1 The materials prepared in Examples 1-4 and Comparative Example 1 were characterized by FTIR, XRD, Raman spectroscopy, SEM, TEM, and X-ray photoelectron spectroscopy.

[0033] (1) Infrared spectroscopy FTIR characterization Fourier transform infrared absorption spectra of five carbon materials: C, Fe-Co / C, Fe-Cu / C, Fe-Mn / C and Fe-Ni / C. Figure 1 3435 cm -1 The left and right sides are the stretching vibrations of OH, 2815 and 2725 cm -1 The left and right sides are the characteristic absorption peaks of unsaturated CH stretching vibration of carbonyl, 2363 cm -1 The left and right are the stretching vibration absorption peaks of carbon-carbon, carbon-nitrogen triple bonds and accumulated double bonds, while 1585, 1386, 1346 cm -1 The left and right sides are the characteristic absorption peaks of the benzene ring. In addition, 1088 cm -1 The left and right are characteristic absorption peaks of COC ether bonds. Based on the appearance of the above Fourier transform infrared absorption spectrum characteristic absorption peaks, it is shown that the undoped and double transition metal doped carbon materials were successfully prepared.

[0034] (2) XRD characterization The X-ray diffraction spectra of five carbon materials are shown in Figure 2. Figure 2As shown. After bimetallic doping, Fe-Co / C, Fe-Cu / C, Fe-Mn / C, and Fe-Ni / C mainly have (002) and (101) crystal planes near 23° and 29°, which mainly correspond to the graphite carbon structure in the carbon material. In addition, there is no obvious metal oxide diffraction peak, indicating that the transition metal exists in the carbon material in the form of single atoms.

[0035] (3) Raman spectroscopy characterization Raman spectra of five carbon materials: C, Fe-Co / C, Fe-Cu / C, Fe-Mn / C and Fe-Ni / C. Figure 3 As shown. The five carbon materials have a wavelength of ~1340 cm -1 (I D )、~1571 cm -1 (I G ) show obvious absorption peaks, corresponding to the C atom lattice defects and sp 2 Hybridized in-plane stretching vibration.

[0036] (4) SEM and TEM characterization The scanning electron microscope (100 nm) of Fe-Co / C is shown in Figure 4(a). The scanning electron microscope photo shows that Fe-Co / C is a layered flower-like morphology with a size of about ~100 nm. The transmission electron microscope photo of Fe-Co / C is shown in Figure 4(bc). Fe-Co / C is a layered transparent structure as a whole. Due to the doping of transition metals, dark particles are evenly distributed in its structure. High-angle annular dark field transmission electron microscope photos show that transition metals are evenly distributed on the surface and inside of Fe-Co / C in the form of single atoms (white bright spots).

[0037] (5) Electronic spectrum characterization The X-ray electron spectrum of Fe-Co / C is as follows Figure 5 As shown, Fe-Co / C contains elements such as C, O, N, Fe, and Co, with contents of 86.65, 12.24, 0.72, 0.20, and 0.19%, respectively, indicating that the doping of Fe and Co elements is successful.

[0038] Test Example 2 The degradation properties of the materials prepared in the examples and comparative examples were tested.

[0039] (1) Test results of tetracycline degradation performance The degradation kinetics of tetracycline (TC) activated by PMS of five carbon materials, Fe-Co / C, Fe-Cu / C, Fe-Mn / C and Fe-Ni / C, are shown in Figure 6 (ac). Among them, the amount of carbon material is 5 mg, the concentration of TC is 10 mg / L, the volume of TC is 50 mL, the amount of PMS is 10-30 mg, and the pH is 5.06. The degradation kinetics and degradation rate of TC activated by PMS of four double transition co-doped carbon materials, Fe-Co / C, Fe-Cu / C, Fe-Mn / C and Fe-Ni / C, are stronger than those of undoped carbon materials. Among them, Fe-Co / C has the strongest activity, which is significantly better than the other three carbon materials under the same conditions. The degradation rate of TC can reach more than 98% after 180 min. It can be seen that Fe-Co / C is the carbon catalytic material with the best performance.

[0040] Effect of Fe-Co / C dosage on tetracycline degradation kinetics Figure 7 As shown. Among them, the amount of carbon catalyst material is 10-30 mg, TC concentration is 10 mg / L, TC volume is 50 mL, PMS amount is 10 mg, pH=5.06. Under different dosages, the degradation rate of TC by Fe-Co / C activated PMS is greater than 98% in about 180 minutes.

[0041] Effect of Fe-Co / C activated PMS on tetracycline degradation kinetics at different pH Figure 8 As shown. Among them, the amount of carbon material is 10 mg, the TC concentration is 10 mg / L, the TC volume is 50 mL, and the PMS amount is 10 mg. When the pH is strong acid or alkaline, the degradation rate of TC is significantly inhibited. When the pH is 5.06 (weakly acidic), the effect of TC is the best.

[0042] Under the conditions of 10 mg carbon material dosage, 10 mg / L TC concentration, 50 mL TC volume, 10 mg PMS dosage, and pH 5.06, the degradation effects of the materials prepared in Examples 1-4 and Comparative Examples 1-4 on tetracycline were tested. The test results are shown in Table 1.

[0043] Table 1 Tetracycline degradation performance test results Group Degradation efficiency% Example 1 98.32 Example 2 99.56 Example 3 98.48 Example 4 97.69 Comparative Example 1 68.53 Comparative Example 2 75.29 Comparative Example 3 83.14 Comparative Example 4 63.28 (2) Test results of commonly used antibiotics Several commonly used antibiotics (amoxicillin, daqingmycin sulfate, ciprofloxacin, erythromycin, cefaclor, tetracycline) such as penicillin, aminoglycoside, quinolone, macrolide, cephalosporin, and tetracycline were selected as representatives, and the degradation efficiency of different types of antibiotics was studied by Fe-Co / C activated PMS. Fig. 9As shown. Among them, the Fe-Co / C dosage is 10 mg, the TC concentration is 10 mg / L, the TC volume is 50 mL, the PMS dosage is 10 mg, t=180 min, T=30 ℃, and pH=5.06. It can be seen that Fe-Co / C, as a carbon catalytic material with excellent performance, has a good oxidative degradation effect on various antibiotics in water, with a degradation rate of 93~99%, and can be used as a potential functional material for water treatment.

[0044] Therefore, the present invention adopts a double transition metal-doped carbon material with the above structure, and its preparation method and application. The doped double transition metal exists in the form of single atoms and has stronger catalytic activity than the original carbon material. Specifically, after activating PMS, it has faster degradation kinetics and stronger degradation efficiency for antibiotics such as tetracycline.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a double transition metal doped carbon material, characterized in that: The following steps are involved: Step 1: Preparation of wood fiber powder Using agricultural and forestry waste as raw materials, wood fiber powder is obtained through drying, crushing and sieving in sequence; Step 2: Doping The wood fiber powder is placed in a reactor, an iron salt solution is added, and the mixture is stirred evenly, and then a transition metal salt is added, and the mixture is stirred until the mixture is evenly distributed, so as to ensure that the iron salt and the transition metal salt are fully dispersed and absorbed by the wood fiber powder to obtain a mixed suspension; Step 3: Pyrolysis The mixed suspension was placed in an oven for drying, and then transferred to a tubular furnace for pyrolysis under a N2 atmosphere, cooled to room temperature, and then alternately washed with clean water and anhydrous ethanol and dried to obtain a double transition metal doped carbon material.

2. The method for preparing a double transition metal doped carbon material according to claim 1, characterized in that: In step 1, 50-100 mesh wood fiber powder is obtained by sieving.

3. The method for preparing a double transition metal doped carbon material according to claim 1, characterized in that: In step 1, the agricultural and forestry waste is one of agricultural waste and forestry waste, the agricultural waste is at least one of bagasse, straw, rice husk, fruit peel and fruit shell, and the forestry waste is at least one of pine, fir and mulberry residue.

4. The method for preparing a double transition metal doped carbon material according to claim 1, characterized in that: In step 2, the iron salt is ferric chloride hexahydrate, and the transition metal salt is one of manganese chloride tetrahydrate, cobalt chloride hexahydrate, copper sulfate pentahydrate and nickel chloride hexahydrate.

5. The method for preparing a double transition metal doped carbon material according to claim 4, characterized in that: In step 2, the total mass of the iron salt and the transition metal salt is 1‰-5‰ of the wood fiber powder, and the molar ratio of the iron salt to the transition metal salt is 1:5-5:

1.

6. The method for preparing a double transition metal doped carbon material according to claim 4, characterized in that: The concentration of iron salt in step 2 is 180~220 mg / L.

7. The method for preparing a double transition metal doped carbon material according to claim 1, characterized in that: In step 3, the calcination temperature in the tubular furnace is 400-1000°C and the calcination time is 1-5 h.

8. The method for preparing a double transition metal doped carbon material according to claim 1, characterized in that: The drying temperature in step 3 is 60-80°C and the drying time is 1-24 h.

9. A double transition metal doped carbon material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of a double transition metal doped carbon material according to claim 9 in the degradation of antibiotics.

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