Preparation method and application of iron-molybdenum co-loaded biochar catalyst

Abstract

The present invention relates to the technical field of the preparation of biochar catalysts, specifically to a preparation method and application of an iron-molybdenum co-loaded biochar catalyst, which includes the following preparation steps: S1. Preparation of a biochar precursor; S2. Introduction of iron and molybdenum elements; S3. Loading modification; S4. Pore structure modification; S5. Secondary pyrolysis. The present invention can degrade tetracycline in water more quickly and efficiently, greatly improving the treatment efficiency, which is of great significance for solving the problem of antibiotic pollution in water. In addition, the application of this process in actual water bodies also shows good degradation effects, with a degradation rate of tetracycline reaching 98.8%, effectively reducing the content of tetracycline in water and reducing the potential harm of antibiotics to the environment and ecosystem.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of biochar catalysts, and specifically to a preparation method and application of an iron-molybdenum co-loaded biochar catalyst. Background Art

[0002] Antibiotics are used in livestock farms to increase production or prevent infections. Livestock manure containing residual antibiotics is further used as fertilizer for crop production and aquaculture, resulting in the entry of antibiotics into the soil, groundwater and aquatic ecosystems. At the same time, due to the high solubility characteristics of antibiotics and the lack of effective treatment measures, antibiotics are directly or indirectly released into different environments.

[0003] Tetracycline (TC) is one of the most widely used antibiotics in the world. The extensive use of a large amount of tetracycline has led to its frequent detection in the environment. It is in the form of light yellow crystals or powder, odorless, bitter, hygroscopic, and gradually darkens when exposed to light. Tetracycline antibiotics include tetracycline, doxycycline, minocycline, tigecycline, oxytetracycline, chlortetracycline, etc. Due to the extensive use of tetracycline antibiotics and the series of environmental safety risks they can cause, to date, the use of biological methods, physical adsorption, advanced oxidation methods and other methods to remove tetracycline has been widely reported.

[0004] In the advanced oxidation method, the ozone / peroxymonosulfate (O3 / PMS) combined process was first proposed by Professor Ma Jun of Harbin Institute of Technology, and the efficient degradation of atrazine was achieved in a short time. Although the ozone / peroxymonosulfate process shows high efficiency in degrading organic pollutants, there are still some limitations in its practical application. First, when ozone or peroxymonosulfate is used alone, the utilization rate of the oxidant is low and the degradation efficiency is limited. Second, the reaction rate of ozone and peroxymonosulfate is slow, especially in complex water bodies, and it is easily interfered by inorganic ions and organic substances, resulting in a decrease in the degradation effect. In addition, the reaction conditions (such as pH, temperature, etc.) of ozone and peroxymonosulfate have a great influence on the degradation efficiency, which limits its application in practical engineering. In order to improve the degradation efficiency of the ozone / peroxymonosulfate process, researchers have tried to introduce catalysts to accelerate the activation of the oxidant and the generation of free radicals. Transition metal catalysts (such as iron, molybdenum, etc.) have become a research hotspot due to their good catalytic performance and low cost. However, the existing iron-molybdenum catalysts have problems such as uneven loading and unstable catalytic activity during the preparation process, which limit their popularization in practical applications. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method and application of an iron-molybdenum co-loaded biochar catalyst, which significantly enhances the degradation efficiency through the iron-molybdenum co-loaded biochar catalyst, and solves the problems of low utilization rates of ozone and persulfate and great influence of complex water components on the degradation efficiency in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A preparation method of an iron-molybdenum co-loaded biochar catalyst, comprising the following preparation steps:

[0008] S1. Preparation of biochar precursor: Wash, dry, and crush the carbon-containing organic matter into powder, pass it through a 100-mesh sieve, and then perform primary pyrolysis in a nitrogen atmosphere to obtain the biochar precursor;

[0009] S2. Introduction of iron and molybdenum elements: Mix the biochar precursor, ferric chloride, and sodium molybdate in a mass ratio of 1:1:1.5, impregnate them in an acetone solution with a mass fraction of 50%, stir at a speed of 100-200 r / min for 22-24 h, then filter and dry to obtain the primary biochar;

[0010] S3. Loading modification: Add the primary biochar obtained in step S2 to the primary modification solution, stir at a speed of 150-250 r / min for 1-2 h at 20-30 °C to obtain the primary modified biochar;

[0011] S4. Pore structure modification: Add the primary modified biochar obtained in step S3 to the secondary modification solution, stir at a speed of 200-300 r / min for 2.5-3.5 h at 50-60 °C, then filter and dry to obtain the secondary modified biochar;

[0012] S5. Secondary pyrolysis: Perform secondary pyrolysis on the secondary modified biochar obtained in step S4 at 500-600 °C for 1.5-2 h to obtain the iron-molybdenum co-loaded biochar catalyst.

[0013] Preferably, the carbon-containing organic matter is one or more of corn straw, wheat straw, and rice straw.

[0014] Preferably, the primary pyrolysis temperature is controlled at 500-600 °C, and the pyrolysis time is 1.5-2 h.

[0015] Preferably, in step S3, the primary modification solution is a mixed solution of 5% cetyltrimethylammonium bromide solution and polyaspartic acid, wherein the mass ratio of the 5% cetyltrimethylammonium bromide solution to polyaspartic acid is 10:1.

[0016] Preferably, in step S4, the secondary modification solution is a mixed solution of 5% disodium ethylenediaminetetraacetate solution and polymaleic anhydride, and the mass ratio of the 5% disodium ethylenediaminetetraacetate solution to polymaleic anhydride is 8:1.

[0017] Preferably, in step S3, the mass ratio of the primary biochar to the primary modification solution is 1:3.

[0018] Preferably, in step S4, the mass ratio of the primary modified biochar to the secondary modification solution is 1:1.

[0019] Preferably, in step S2, the drying temperature is 60 - 70 °C and the time is 10 - 12 h.

[0020] Preferably, in step S4, the drying temperature is 80 - 90 °C and the time is 5 - 8 h.

[0021] Application of an iron-molybdenum co-loaded biochar catalyst prepared according to the above preparation method in degrading tetracycline in water.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. In the present invention, the primary modification solution can make iron and molybdenum ions disperse more evenly on the surface of the biochar, increasing the number of active sites. It can also make iron and molybdenum ions enter the pores of the biochar more fully, achieving more uniform and deeper loading, thereby improving the catalytic efficiency of the catalyst and enhancing the catalytic performance. The polyaspartic acid therein contains multiple carboxyl groups, which can form stable chelates with various metal ions, making the metal ions disperse evenly on the surface of the biochar, enhancing the binding ability between the metal ions and the surface functional groups of the biochar, and improving the loading efficiency.

[0024] 2. The adsorption of the secondary modification solution on the surface of the biochar in the present invention helps to improve the pore structure of the biochar, making its pores more uniform and open, which is beneficial to the loading of metal ions. It complements the primary modification solution and better improves the catalytic efficiency of the catalyst and enhances the catalytic performance.

[0025] 3. The present invention can degrade tetracycline in water more quickly and efficiently, greatly improving the treatment efficiency, which is of great significance for solving the problem of antibiotic pollution in water. In addition, the application of this process in actual water also shows good degradation effects, and the degradation rate of tetracycline can reach 98.8%, effectively reducing the content of tetracycline in water and reducing the potential harm of antibiotics to the environment and ecosystem. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart for the preparation of the iron-molybdenum co-loaded biochar catalyst of the present invention;

[0027] Figure 2The three-dimensional fluorescence spectra of tetracycline water samples are configured for the water samples at the fine grille of the Southeast Wastewater Treatment Plant. Among them, a is the three-dimensional fluorescence spectrum of the untreated water sample without tetracycline, b is the three-dimensional fluorescence spectrum of the untreated water sample containing tetracycline, c is the three-dimensional fluorescence spectrum of the water sample after 20 minutes of treatment, and d is the three-dimensional fluorescence spectrum of the water sample after 60 minutes of treatment;

[0028] Figure 3 This is a line graph showing the effect of the iron-molybdenum co-loaded biochar catalyst of the present invention in degrading tetracycline water samples under different water quality conditions;

[0029] Figure 4 This is a schematic diagram of the structure of the iron-molybdenum co-loaded biochar catalyst obtained in Example 1 and Comparative Examples 1-3 of the present invention under an electron microscope. Among them, a, b, and c are the observation results of the product obtained in Comparative Example 1 at magnifications of 3000 times, 2000 times, and 1000 times respectively, d, e, and f are the observation results of the product obtained in Comparative Example 2 at magnifications of 20000 times, 5000 times, and 2000 times respectively, g, h, and i are the observation conditions of the product obtained in Comparative Example 3 at magnifications of 5000 times, 3000 times, and 2000 times respectively, j, k, and l are the observation conditions of the newly obtained product in Example 1 at magnifications of 20000 times, 5000 times, and 2000 times respectively, and m, n, and o are the observation conditions of the product obtained and used in Example 1 at magnifications of 20000 times, 10000 times, and 2000 times respectively;

[0030] Figure 5 This is the EDS energy spectrum diagram of the iron-molybdenum co-loaded biochar catalyst obtained in Example 1 of the present invention;

[0031] Figure 6 This is the nitrogen adsorption-desorption isotherm curve graph of BC, FeBC, MoBC, FeMoBC (new), and FeMoBC (used). Among them, BC is the product obtained in Comparative Example 1, FeBC is the product obtained in Comparative Example 2, MoBC is the product obtained in Comparative Example 3, FeMoBC (new) is the iron-molybdenum co-loaded biochar catalyst prepared in Example 1, and FeMoBC (used) is the iron-molybdenum co-loaded biochar catalyst after use;

[0032] Figure 7 This is the XRD spectrum diagram of the iron-molybdenum co-loaded biochar catalyst obtained in Example 1 of the present invention and after use. Among them, FeMoBC (new) is the iron-molybdenum co-loaded biochar catalyst prepared in Example 1, and FeMoBC (used) is the iron-molybdenum co-loaded biochar catalyst after use;

[0033] Figure 8Full-spectrum diagrams of the newly prepared and used materials of the iron-molybdenum co-loaded biochar catalyst obtained in Example 1 of the present invention. Among them, FeMoBC(new) is the iron-molybdenum co-loaded biochar catalyst prepared in Example 1, and FeMoBC(used) is the product of Example 1 after use;

[0034] Figure 9 Element XPS analysis spectra of the newly prepared and used iron-molybdenum co-loaded biochar catalyst obtained in Example 1 of the present invention. Among them, a is the XPS analysis spectrum of the C1 orbital electrons of the C element of the newly prepared product in Example 1, b is the XPS analysis spectrum of the C1 orbital electrons of the C element of the product in Example 1 after use, c is the XPS analysis spectrum of the 2p orbital electrons of the Fe element of the newly prepared product in Example 1, d is the XPS analysis spectrum of the 2p orbital electrons of the Fe element of the product in Example 1 after use, e is the XPS analysis spectrum of the 3d orbital electrons of the Mo element of the newly prepared product in Example 1, and f is the XPS analysis spectrum of the 3d orbital electrons of the Mo element of the product in Example 1 after use;

[0035] Figure 10 Kinetic fitting diagram for exploring the effect of the dosage of the iron-molybdenum co-loaded biochar catalyst of the present invention on the degradation efficiency of tetracycline;

[0036] Figure 11 Kinetic fitting diagram for exploring the effect of the concentration of potassium persulfate solution on the degradation efficiency of tetracycline in the present invention;

[0037] Figure 12 Kinetic fitting diagram for exploring the effect of the initial concentration of tetracycline on the degradation efficiency in the present invention;

[0038] Figure 13 Kinetic fitting diagram for exploring the effect of the concentration of ozone on the degradation efficiency of tetracycline in the present invention;

[0039] Figure 14 Kinetic fitting diagram for exploring the effect of the pH value of the water environment on the degradation efficiency of tetracycline in the present invention;

[0040] Figure 15 Reaction flow chart of the O3 / PMS / FeMoBC system for exploring the effect of the O3 / PMS / FeMoBC system on the degradation of tetracycline in the performance test of the present invention. Detailed implementation manners

[0041] Next, in combination with the embodiments of the present invention, the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] Please refer to Figures 1 - 15 , the present invention provides a technical solution:

[0043] Example 1

[0044] A preparation method of an iron-molybdenum co-loaded biochar catalyst:

[0045] S1. Preparation of biochar precursor: Wash, dry, crush the carbon-containing organic matter into powder, pass through a 100-mesh sieve, and then carry out primary pyrolysis in a nitrogen atmosphere. The primary pyrolysis temperature is controlled at 500 °C, and the pyrolysis time is 1.5 h to obtain the biochar precursor;

[0046] S2. Introduction of iron and molybdenum elements: Mix 100 g of the biochar precursor, 100 g of ferric chloride, and 150 g of sodium molybdate, and impregnate them in 500 mL of an acetone solution with a mass fraction of 50%. Stir at a speed of 100 r / min for 22 h, then filter and dry. The drying temperature is 60 °C, and the time is 10 h to obtain the primary biochar;

[0047] S3. Loading modification: Add the primary biochar obtained in step S2 to a primary modification solution with a mass three times that of the primary biochar, and stir at a speed of 150 r / min at 20 °C for 1 h to obtain the primary modified biochar;

[0048] S4. Pore structure modification: Add the primary modified biochar obtained in step S3 to the secondary modification solution, stir at a speed of 200 r / min at 50 °C for 2.5 h, then filter and dry. The drying temperature is 80 °C, and the time is 5 h to obtain the secondary modified biochar;

[0049] S5. Secondary pyrolysis: Carry out secondary pyrolysis on the secondary modified biochar obtained in step S4 at 500 °C, and the pyrolysis time is 1.5 h to obtain the iron-molybdenum co-loaded biochar catalyst.

[0050] Example 2

[0051] A preparation method of an iron-molybdenum co-loaded biochar catalyst:

[0052] S1. Preparation of biochar precursor: Wash, dry, crush the carbon-containing organic matter into powder, pass through a 100-mesh sieve, and then carry out primary pyrolysis in a nitrogen atmosphere. The primary pyrolysis temperature is controlled at 600 °C, and the pyrolysis time is 2 h to obtain the biochar precursor;

[0053] S2. Introduction of iron and molybdenum elements: 90 g of biochar precursor, 90 g of ferric chloride, and 135 g of sodium molybdate are mixed and impregnated in an acetone solution with a mass fraction of 50%. After stirring at a speed of 200 r / min for 24 h, filtration and drying are carried out. The drying temperature is 70 °C and the time is 12 h to obtain primary biochar;

[0054] S3. Loading modification: The primary biochar obtained in step S2 is added to a primary modification solution with a mass three times that of the primary biochar, and stirred at a speed of 250 r / min at 30 °C for 2 h to obtain primary modified biochar;

[0055] S4. Pore structure modification: The primary modified biochar obtained in step S3 is added to a secondary modification solution with the same mass as the primary modified biochar, and stirred at a speed of 300 r / min at 60 °C for 3.5 h, followed by filtration and drying. The drying temperature is 90 °C and the time is 8 h to obtain secondary modified biochar;

[0056] S5. Secondary pyrolysis: The secondary modified biochar obtained in step S4 is subjected to secondary pyrolysis at 600 °C for 2 h to obtain an iron-molybdenum co-loaded biochar catalyst.

[0057] Example 3

[0058] A preparation method of an iron-molybdenum co-loaded biochar catalyst:

[0059] S1. Preparation of biochar precursor: The carbon-containing organic matter is washed, dried, crushed into powder and passed through a 100-mesh sieve, and then subjected to primary pyrolysis in a nitrogen atmosphere. The primary pyrolysis temperature is controlled at 550 °C and the pyrolysis time is 1.7 h to obtain the biochar precursor;

[0060] S2. Introduction of iron and molybdenum elements: 95 g of biochar precursor, 95 g of ferric chloride, and 142.5 g of sodium molybdate are mixed and impregnated in an acetone solution with a mass fraction of 50%. After stirring at a speed of 150 r / min for 23 h, filtration and drying are carried out. The drying temperature is 63 °C and the time is 11 h to obtain primary biochar;

[0061] S3. Loading modification: The primary biochar obtained in step S2 is added to a primary modification solution with a mass three times that of the primary biochar, and stirred at a speed of 200 r / min at 25 °C for 1.5 h to obtain primary modified biochar;

[0062] S4. Pore structure modification: Add the primary modified biochar obtained in step S3 to a secondary modification solution with the same mass as the primary modified biochar, stir at a speed of 250 r / min at 55 °C for 3 h, then filter and dry. The drying temperature is 85 °C and the time is 6 h to obtain the secondary modified biochar;

[0063] S5. Secondary pyrolysis: Perform secondary pyrolysis on the secondary modified biochar obtained in step S4 at 550 °C for 1.7 h to obtain the iron-molybdenum co-loaded biochar catalyst.

[0064] Example 4

[0065] A preparation method of an iron-molybdenum co-loaded biochar catalyst:

[0066] S1. Preparation of biochar precursor: Wash, dry, and crush the carbon-containing organic matter into powder, pass through a 100-mesh sieve, and then perform primary pyrolysis under a nitrogen atmosphere. The primary pyrolysis temperature is controlled at 580 °C and the pyrolysis time is 1.9 h to obtain the biochar precursor;

[0067] S2. Introduction of iron and molybdenum elements: Mix 100 g of biochar precursor, 100 g of ferric chloride, and 150 g of sodium molybdate, impregnate them in an acetone solution with a mass fraction of 50%, stir at a speed of 180 r / min for 23.5 h, then filter and dry. The drying temperature is 68 °C and the time is 11.5 h to obtain the primary biochar;

[0068] S3. Loading modification: Add the primary biochar obtained in step S2 to a primary modification solution with a mass 3 times that of the primary biochar, stir at a speed of 230 r / min at 28 °C for 1.8 h to obtain the primary modified biochar;

[0069] S4. Pore structure modification: Add the primary modified biochar obtained in step S3 to a secondary modification solution with the same mass as the primary modified biochar, stir at a speed of 280 r / min at 58 °C for 3.3 h, then filter and dry. The drying temperature is 88 °C and the time is 7 h to obtain the secondary modified biochar;

[0070] S5. Secondary pyrolysis: Perform secondary pyrolysis on the secondary modified biochar obtained in step S4 at 580 °C for 1.8 h to obtain the iron-molybdenum co-loaded biochar catalyst.

[0071] Comparative Example 1

[0072] The differences between Comparative Example 1 and Example 1 are as follows. The only difference is that sodium molybdate and ferric chloride are not added in step S2, and the remaining steps are exactly the same in Comparative Example 1 and Example 1.

[0073] Comparative Example 2

[0074] Comparative Example 2 is different from Example 1 only in that sodium molybdate is not added in step S2, and the remaining steps are exactly the same in Comparative Example 2 and Example 1.

[0075] Comparative Example 3

[0076] Comparative Example 3 is different from Example 1 only in that ferric chloride is not added in step S2, and the remaining steps are exactly the same in Comparative Example 3 and Example 1.

[0077] Performance test:

[0078] To verify the degradation ability of the iron-molybdenum co-loaded biochar catalyst in actual complex water bodies, water samples from the fine grille of the Southeast Sewage Treatment Plant in Changchun, Jilin Province were used for experiments. After the retrieved raw water was left standing for 24 hours, it was filtered twice with a 50-μm qualitative filter paper and used as a solvent to prepare a 30-μM tetracycline solution. At the same time, the water quality analysis results obtained by detecting the water sample parameters using a UV spectrophotometer and a three-dimensional fluorescence spectrometer and the results of the three-dimensional fluorescence distribution method are shown in Tables 1 and 2 below:

[0079] Table 1 Water quality analysis results of water samples from the fine grille of the Southeast Sewage Treatment Plant

[0080] Water quality indicators Before treatment (including tetracycline) After treatment COD 204.68 mg / L 45.61 mg / L TN 39.68 mg / L 25.06 mg / L NH3-N 33.93 mg / L 21.24 mg / L TP 5.59 mg / L 4.55 mg / L pH 7.41 6.48

[0081] Table 2 Three-dimensional fluorescence distribution method

[0082]

[0083] The three-dimensional fluorescence spectrogram of the water sample is as shown in the appendix Figure 2 It can be seen that the organic substances in the solution mainly exist between regions III, IV, and V (240 - 400 nm / 350 - 550 nm), and are judged to be aromatic proteins or phenolic substances (Fulvic acid) and humic acid substances. In the appendix Figure 2 After the iron-molybdenum co-loaded biochar catalyst was treated for 20 minutes, the fluorescent substances in the raw water sample decreased significantly; in the 60-minute water sample, the fluorescent regions in the three-dimensional fluorescence spectrogram almost disappeared, indicating that most of the fluorescent organic substances were degraded below the detection limit. As the oxidative degradation proceeded, the content of the relevant organic substances gradually decreased.

[0084] Appendix Figure 3It is a line chart showing the effect of the iron-molybdenum co-loaded biochar catalyst on the degradation of tetracycline water samples under different water quality conditions. Compared with the deionized water sample, the time required to degrade the target pollutant dissolved in the raw water sample to less than 90% increased by 6 minutes. The complex water sample had a certain impact on the degradation efficiency of the iron-molybdenum co-loaded biochar catalyst. The main reason was that there were various types of inorganic salts and other complex organic substances in the raw water sample. During the oxidative degradation process, they interfered by quenching active oxidative substances and competing with the target pollutant for active oxidative substances respectively. However, there was still a 98.8% degradation rate for tetracycline in the water. This result further indicated that the present invention had certain applicability in degrading tetracycline in the presence of actual water bodies.

[0085] 1. Characterization and analysis by electron microscope-energy dispersive spectrometer

[0086] Characterization and analysis by electron microscope-energy dispersive spectrometer (SEM-EDS): The morphology of the iron-molybdenum co-loaded biochar catalysts obtained in Example 1 and Comparative Examples 1-3 was observed and the energy spectrum was tested using a TESCAN MIRA LMS scanning electron microscope. The results are as follows Figure 4 shown. In the figure, a, b, and c are the observation results of the product obtained in Comparative Example 1 at magnifications of 3000 times, 2000 times, and 1000 times respectively, d, e, and f are the observation results of the product obtained in Comparative Example 2 at magnifications of 20000 times, 5000 times, and 2000 times respectively, g, h, and i are the observation situations of the product obtained in Comparative Example 3 at magnifications of 5000 times, 3000 times, and 2000 times respectively, and j, k, and l are the observation situations of the newly obtained product in Example 1 at magnifications of 20000 times, 5000 times, and 2000 times respectively. The element composition in the iron-molybdenum co-loaded biochar catalyst was clarified by EDS analysis. As follows Figure 5 shown, there are elements such as carbon, oxygen, iron, and molybdenum in the iron-molybdenum co-loaded biochar catalyst, and their mass percentages are 41.56%, 26.31%, 18.82%, and 13.31% respectively; their atomic weight percentages are 62.03%, 29.45%, 6.02%, and 2.5% respectively.

[0087] 2. Specific surface area and pore structure analysis

[0088] Specific surface area and pore structure analysis (BET analysis): The total specific surface area, total pore volume, pore diameter and other data of the material were measured using a Micromeritics ASAP2460 type fully automatic specific surface area and porosity analyzer. The results are as follows Figure 6 shown. As follows Figure 6Nitrogen adsorption - desorption isotherm curves of BC, FeBC, MoBC, FeMoBC (new) and FeMoBC (used). Among them, BC is the product obtained in Comparative Example 1, FeBC is the product obtained in Comparative Example 2, MoBC is the product obtained in Comparative Example 3, FeMoBC (new) is the iron - molybdenum co - loaded biochar catalyst prepared in Example 1, and FeMoBC (used) is the iron - molybdenum co - loaded biochar catalyst after use. The curve shows a slow upward trend, indicating that the catalyst has more mesoporous structures.

[0089] 3. X - ray diffraction analysis

[0090] X - ray diffraction analysis (XRD analysis) is used to characterize the solid - phase crystal structure of biochar. The crystal structures of the iron - molybdenum co - loaded biochar catalyst before and after use are determined through XRD patterns. The iron - molybdenum co - loaded biochar catalyst obtained in Example 1 is measured using a Rigaku SmartLabSE instrument made in Japan. The results are as shown Figure 7 below. The XRD analysis results indicate that the synthesis of the iron - molybdenum co - loaded biochar catalyst is successful. 4. X - ray photoelectron spectroscopy analysis

[0091] X - ray photoelectron spectroscopy analysis (XPS analysis) is tested using a Thermo Scientific K - Alpha XPS instrument. The results are as shown in Figure 8 and Figure 9 below, where Figure 8 is the full - spectrum diagram of the newly prepared and used materials of the iron - molybdenum co - loaded biochar catalyst obtained in Example 1; in Figure 9 a is the XPS spectrum analysis of the C1 orbital electrons of the C element of the newly prepared product in Example 1, b is the XPS spectrum analysis of the C1 orbital electrons of the C element of the product in Example 1 after use, c is the XPS spectrum analysis of the 2p orbital electrons of the Fe element of the newly prepared product in Example 1, d is the XPS spectrum analysis of the 2p orbital electrons of the Fe element of the product in Example 1 after use, e is the XPS spectrum analysis of the 3d orbital electrons of the Mo element of the newly prepared product in Example 1, and f is the XPS spectrum analysis of the 3d orbital electrons of the Mo element of the product in Example 1 after use. The XPS results show that various valence states of FeO x and MoO x are doped on the surface of the iron - molybdenum co - loaded biochar catalyst obtained in Example 1, which is consistent with the detection results of XRD, further indicating the successful synthesis of the iron - molybdenum co - loaded biochar catalyst.

[0092] 5. Explore the effect of the dosage of the iron - molybdenum co - loaded biochar catalyst on the degradation efficiency of tetracycline (TC)

[0093] The water body was taken from the fine grille of the Southeast Sewage Treatment Plant in Changchun City, Jilin Province. Under the conditions of an aqueous phase temperature of 25 ± 1 °C, a concentration of persulfate (PMS) of 30 μM, a gaseous ozone concentration of 3.6 mg / L, a concentration of the solution containing tetracycline of 0.03 mM, and a solution pH of 6.8 ± 0.1, the dosages of the material were controlled at 50, 100, 200, 300, and 500 mg / L respectively to investigate the effect of the dosage of the functional material in the O3 / PMS / FeMoBC process on the degradation efficiency of TC. The reaction flow chart of the O3 / PMS / FeMoBC system is shown in the appendix Figure 15 as follows

[0094] The results are shown in the appendix Figure 10 as follows. The reaction rate of the O3 / PMS / FeMoBC system was significantly improved compared with that of O3 and O3 / PMS. It can be seen from the figure that the addition of the catalyst greatly increased the k obs value. Under the same conditions, O3 / PMS / FeMoBC was higher than the individual O3 and O3 / PMS processes. When the catalyst dosage was 200 mg / L, the degradation rate reached 94.3% at 8 min, while the time points for O3 and O3 / PMS to reach this degradation rate under the same conditions were 20 min. When the dosage increased from 50 mg / L to 200 mg / L, the degradation rate increased from 89% degraded in 14 min to 98.6%. However, when the dosage increased from 200 mg / L to 500 mg / L, the increase in its degradation efficiency was extremely small. It is speculated that the reason is that the added material did not diffuse evenly into the reactor, resulting in a slow increase in its degradation efficiency. Therefore, in order to remove tetracycline in water and save costs, when considering other influencing factors in this experiment, the material dosage was set at 200 mg / L

[0095] 6. Explore the effect of the concentration of potassium peroxymonosulfate solution (PMS) on the degradation efficiency of tetracycline (TC)

[0096] The water body was taken from the fine grille of the Southeast Sewage Treatment Plant in Changchun City, Jilin Province. Under the conditions of controlling the aqueous phase temperature at 25 ± 1 °C, a gaseous ozone concentration of 3.6 mg / L, a FeMoBC material dosage of 200 mg / L, a concentration of the solution containing tetracycline of 30 μM, and a solution pH of 6.8 ± 0.1, the PMS concentration was controlled at 5 μM, 10 μM, 30 μM, 50 μM, and 80 μM to investigate the effect of the PMS concentration on the degradation efficiency under the O3 / PMS / FeMoBC process

[0097] The results are shown in the appendix Figure 11 as follows. The influence trend of the PMS concentration on O3 / PMS / FeMoBC was the same as that of the O3 / PMS process. When the PMS concentration increased from 5 μM to 50 μM, its k obsThe value gradually increases, and more PMS in the system improves the overall reaction rate. This indicates that within a certain concentration range, the increase in the value of PMS is positively correlated with the catalytic efficiency of FeMoBC.

[0098] 7. Explore the effect of the initial concentration of tetracycline (TC) on the degradation efficiency

[0099] The water body was taken from the fine grille of the Southeast Sewage Treatment Plant in Changchun, Jilin Province. The experiment was carried out under the conditions of controlling the aqueous phase temperature at 25 ± 1 °C, the concentration of potassium bisulfate solution at 30 μM, the gaseous ozone concentration at 3.6 mg / L, the dosage of FeMoBC material at 200 mg / L, and the solution pH at 6.8 ± 0.1. The initial concentration of tetracycline was controlled at 0.01 mM, 0.02 mM, 0.03 mM, 0.04 mM, and 0.05 mM to investigate the effect of the initial concentration of tetracycline on the degradation efficiency under the O3 / PMS / FeMoBC process.

[0100] The results are as follows Figure 12 shown. The degradation rate of the O3 / PMS / FeMoBC system is higher than that of the single O3 and O3 / PMS methods, and the reaction rate decreases with the increase in the TC concentration. When the TC concentration is 0.03 mM, its k obs = 0.307 min -1 , which is 141.7% and 65.05% higher than those of the O3 and O3 / PMS processes respectively. Even when the TC concentration is 0.05 mM, within 20 min, the degradation rate of this process is still as high as 99%.

[0101] 8. Explore the effect of the concentration of ozone on the degradation efficiency of tetracycline (TC)

[0102] The water body was taken from the fine grille of the Southeast Sewage Treatment Plant in Changchun, Jilin Province. The experiment was carried out under the conditions of controlling the aqueous phase temperature at 25 ± 1 °C, the concentration of potassium bisulfate solution at 30 μM, the solution pH at 6.8 ± 0.1, the dosage of FeMoBC material at 200 mg / L, and the concentration of the solution containing tetracycline at 0.03 mM. The gaseous ozone concentration was controlled at 1.2 mg / L, 2.4 mg / L, 3.6 mg / L, 4.8 mg / L, 6 mg / L, and Air (introducing air) to investigate the effect of the gaseous ozone concentration on the degradation efficiency under the O3 / PMS / FeMoBC process. Among them, the control group with air introduced only adjusted the current of the ozone generator to zero, and the other parameters were the same as those when O3 = 6 mg / L.

[0103] The results are as follows Figure 13 shown. The effect of the gaseous ozone concentration on the degradation efficiency in the O3 / PMS / FeMoBC process is similar to that of the O3 and O3 / PMS processes. Along with the increase in the ozone concentration, the k of the reaction system obsIt increases accordingly. The main reason is that the half-life of ·OH is relatively short, and self-quenching and free radical competition phenomena rarely occur. In addition, the increase in the concentration of ·OH also helps to increase the concentration of SO4 ·- and strengthen the decomposition ability of PMS, further improving the utilization rate of the oxidant. Compared with O3 and O3 / PMS, the addition of FeMoBC significantly increases the k obs value, confirming the high catalytic efficiency of FeMoBC. In addition, in the Air group, we further clarified the key role of O3 in O3 / PMS / FeMoBC.

[0104] 8. Explore the influence of the pH value of the water environment on the degradation efficiency

[0105] The water body was taken from the fine grille of the Southeast Sewage Treatment Plant in Changchun City, Jilin Province. The experiment was carried out under the conditions of controlling the aqueous phase temperature at 25±1°C, the concentration of potassium bisulfate solution at 30 μM, the gaseous ozone concentration at 3.6 mg / L, the dosage of FeMoBC material at 200 mg / L, the solution pH at 6.8±0.1, and the concentration of the solution containing tetracycline at 0.03 mM. The solution pH value was controlled at 3.0, 5.0, 7.0, 9.0, and 11.0 to investigate the influence of the pH value of the water environment on the degradation efficiency under the O3 / PMS / FeMoBC process.

[0106] The results are as shown in the appendix Figure 14 . As shown, during the process of the pH in the reaction system changing from acidic to neutral and then to weakly alkaline, the degradation rate of tetracycline by O3 / PMS / FeMoBC first increases and then decreases. When pH = 5, the degradation rate reaches the maximum, indicating that the acidic condition is not conducive to the generation of hydroxyl groups but is conducive to the circulation of iron ions. The optimal pH is between 5 and 7. Within this range, the solubility of iron ions is relatively high, which is conducive to the reaction; the stability of ozone molecules is better, which will also improve the oxidation and decomposition efficiency. In addition, the pH adaptation range of O3 / PMS / FeMoBC is wider than that of the O3 and O3 / PMS processes. Even in the worst case of pH = 11 (k obs = 0.18113 min -1 ), as shown in its kinetic fitting graph, its fluctuation range is still smaller than that of the O3 and O3 / PMS processes.

[0107] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of an iron-molybdenum co-loaded biochar catalyst, characterized in that, It includes the following preparation steps: S1. Preparation of biochar precursor: Wash the carbon-containing organic matter, dry it, crush it into powder, pass it through a 100-mesh sieve, and then perform primary pyrolysis under the atmosphere of nitrogen to obtain the biochar precursor; S2. Introduction of iron and molybdenum elements: Mix the biochar precursor, ferric chloride, and sodium molybdate in a mass ratio of 1:1:1.5, impregnate them in an acetone solution with a mass fraction of 50%, stir at a rotation speed of 100 - 200 r / min for 22 - 24 h, then filter and dry to obtain the primary biochar; S3. Loading modification: Add the primary biochar obtained in step S2 into the primary modification solution, stir at a rotation speed of 150 - 250 r / min at 20 - 30 °C for 1 - 2 h to obtain the primary modified biochar; S4. Pore structure modification: Add the primary modified biochar obtained in step S3 into the secondary modification solution, stir at a rotation speed of 200 - 300 r / min at 50 - 60 °C for 2.5 - 3.5 h, then filter and dry to obtain the secondary modified biochar; S5. Secondary pyrolysis: Perform secondary pyrolysis on the secondary modified biochar obtained in step S4 at 500 - 600 °C for 1.5 - 2 h to obtain the iron-molybdenum co-loaded biochar catalyst; The primary modification solution is a mixed solution of 5% cetyltrimethylammonium bromide solution and polyaspartic acid, wherein the mass ratio of the 5% cetyltrimethylammonium bromide solution to polyaspartic acid is 10:1; The secondary modification solution is a mixed solution of 5% disodium ethylenediaminetetraacetate solution and polymaleic anhydride, wherein the mass ratio of the 5% disodium ethylenediaminetetraacetate solution to polymaleic anhydride is 8:

1.

2. The preparation method of an iron-molybdenum co-loaded biochar catalyst according to claim 1, characterized in that, The carbon-containing organic matter is one or more of corn straw, wheat straw, and rice straw.

3. The preparation method of an iron-molybdenum co-loaded biochar catalyst according to claim 1, characterized in that, In step S1, the primary pyrolysis temperature is controlled at 500 - 600 °C, and the pyrolysis time is 1.5 - 2 h.

4. The preparation method of an iron-molybdenum co-loaded biochar catalyst according to claim 1, wherein, In step S3, the mass ratio of the primary biochar to the primary modification solution is 1:

3.

5. The preparation method of an iron-molybdenum co-loaded biochar catalyst according to claim 1, characterized in that, In step S4, the mass ratio of the primary modified biochar to the secondary modification solution is 1:

1.

6. The preparation method of an iron-molybdenum co-loaded biochar catalyst according to claim 1, characterized in that, In step S2, the drying temperature is 60 - 70 °C, and the time is 10 - 12 h.

7. The preparation method of an iron-molybdenum co-loaded biochar catalyst according to claim 1, characterized in that, In step S4, the drying temperature is 80 - 90 °C, and the time is 5 - 8 h.

8. Application of an iron-molybdenum co-loaded biochar catalyst prepared by the preparation method according to any one of claims 1 - 7 in degrading tetracycline in water.

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