Application of charcoal / metal oxide composite material in antibiotic elimination

Abstract

The invention belongs to the technical field of water environment purification, and relates to a water treatment technology, in particular to application of a charcoal / metal oxide composite material in antibiotic elimination. According to the application, high-concentration antibiotics in a water body are efficiently eliminated by utilizing the adsorption of the biochar / metal oxide composite material on the antibiotics and cooperating with the photocatalytic degradation effect, and the elimination speed and the elimination rate are high. The biochar / metal oxide composite material is added into an antibiotic aqueous solution in proportion, and antibiotics can be eliminated under the illumination condition after the biochar / metal oxide composite material is dispersed. A base material of the composite material is a biochar base material, a metal oxide is loaded on the surface of the biochar base material, the loading capacity of the metal oxide ranges from 15 wt% to 60 wt%, and the biochar base material is prepared through the steps that firstly, lignocellulose biomass serves as a raw material and is evenly mixed with a hard template agent according to the proportion, and then pyrolysis is conducted to prepare the biochar base material; and carrying out in-situ loading of a metal oxide on the surface of the biochar base material through hydro-thermal synthesis.

Description

Technical Field

[0001] The present invention belongs to the technical field of water environment purification, relates to a water treatment technology, and particularly relates to application of a biochar / metal oxide composite material in eliminating antibiotics. Background Art

[0002] With the acceleration of urbanization and industrialization, many new organic pollutants, such as antibiotics, hormones, personal care products, and food additives, have appeared in the aquatic environment. These pollutants are stable, difficult to degrade, and pose serious risks, attracting widespread attention. Among them, antibiotics are a class of chemical pollutants that pose a potential threat to human health and the ecological environment.

[0003] Photocatalytic technology can degrade organic pollutants into harmless small molecules such as CO2 and H2O, and is gaining increasing attention for removing antibiotics from water. Commonly used photocatalysts include TiO2, ZnO, SnO2, C3N4, BiVO4, ZrO2, MOFs, and CdS. However, some catalysts face challenges during use, such as aggregation, rapid electron-hole recombination (e.g., C3N4), and high cost (e.g., Pt), limiting their commercial application.

[0004] Existing research indicates that using a carrier to support photocatalysts can effectively avoid agglomeration and enhance the photocatalytic activity and stability of the catalyst. Photocatalytic materials have been combined with carbon-based materials such as semiconductors (C₃N₄ and carbon spheres), metal oxides (TiO₂ and biochar), and metal sulfides (MoS₂ and carbon quantum dots) to prepare and apply photocatalytic composites. The use of these composites can improve the efficiency of photogenerated electron-hole pair separation in photocatalysts. Research also indicates that biochar, as a suitable support material, possesses advantages such as a large specific surface area and numerous surface active sites. These properties enable rapid charge shuttle and act as an electron reservoir, promoting enhanced charge separation and playing a key role in photocatalysis.

[0005] Furthermore, the economic benefits of biochar depend on its cost and selling price. According to literature, biochar pyrolyzed at 300°C sells for $220 / ton, and biochar pyrolyzed at 450°C sells for $280 / ton. The value gained from biochar offsets the economic costs of biomass feedstock, harvesting, transportation, and storage, as well as the costs of pyrolysis, transportation, and application. This means that the net profit from biochar production can be increased through cheaper feedstock and promising processing technologies. With the development of biochar production technologies, the cost of biochar is expected to further decrease, and the biochar industry has a vast market potential and promising prospects. The development of biochar as a photocatalytic carrier will help realize the resource utilization of biomass. The application of high-performance biochar to eliminate antibiotics in water bodies will undoubtedly bring significant economic, social, and environmental benefits.

[0006] With the development of society and the demands of industrial production, the elimination of antibiotics at higher initial concentrations and faster kinetic rates is required. Single-use photocatalytic technology is only suitable for removing low-concentration organic pollutants from water. The development and application of high-performance biochar / metal oxide composites that utilize both adsorption and photocatalysis to eliminate high-concentration antibiotics are relatively rare. Improving the ability of biochar / metal oxide composites to eliminate high-concentration antibiotics in water while reducing production costs is a key technical challenge in this field and crucial for the commercialization and application of these materials.

[0007] Therefore, the development of low-cost, high-efficiency and environmentally friendly biochar / metal oxide composites and their application in the elimination of high-concentration antibiotics in water bodies has important scientific significance and practical value. Summary of the Invention

[0008] Based on this, the purpose of the present invention is to provide an application of a biochar / metal oxide composite material in the elimination of antibiotics, through the adsorption of antibiotics by the composite material and the synergistic photocatalytic degradation effect, to achieve rapid elimination of high-concentration antibiotics in water.

[0009] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides an application of a biochar / metal oxide composite material in eliminating antibiotics.

[0010] Furthermore, the application is to utilize the adsorption of the antibiotic by the biochar / metal oxide composite material and the synergistic photocatalytic degradation effect to achieve the application of eliminating the antibiotic.

[0011] Furthermore, the biochar / metal oxide composite material is dispersed in the antibiotic aqueous solution in a proportionate manner, and the antibiotic is eliminated under light conditions. The mass ratio of the antibiotic aqueous solution to the biochar / metal oxide composite material is 1000:0.8-1.2. The illumination method is ultraviolet light. When the concentration of the antibiotic aqueous solution is ≤200 mg / L, especially when the concentration is between 50 mg / L and 200 mg / L, and the illumination time is set to 10-120 minutes, the antibiotic removal rate in the antibiotic aqueous solution reaches 90%-100%.

[0012] Furthermore, the substrate of the biochar / metal oxide composite material is a biochar substrate, the surface of the biochar substrate is loaded with the metal oxide, and the loading amount of the metal oxide is in the range of 15wt% to 60wt%. Furthermore, the biochar substrate is a mesoporous carbon material with a specific surface area of 1288.34 m 2 / g, pore volume 1.086cm3 / g, and the mesopore volume is 0.721cm 2 / g; the metal oxide includes TiO2 or SnO2; the antibiotics include tetracycline antibiotics, fluoroquinolone antibiotics or sulfonamide antibiotics; the tetracycline antibiotics include tetracycline, the fluoroquinolone antibiotics include ciprofloxacin or enrofloxacin, and the sulfonamide antibiotics include sulfadiazine.

[0013] The present invention further provides a method for preparing the biochar / metal oxide composite material described in the above application, firstly, lignocellulosic biomass is used as a raw material and mixed with a hard template in proportion and then pyrolyzed to prepare a biochar substrate; then, metal oxides are in situ loaded on the surface of the biochar substrate through hydrothermal synthesis to obtain the biochar substrate.

[0014] Furthermore, the lignocellulosic biomass includes straw, bamboo or peanut shell, preferably bamboo; the hard template includes basic magnesium carbonate, magnesium oxide or slag, preferably basic magnesium carbonate.

[0015] Furthermore, the biochar substrate preparation process includes: ball-milling the lignocellulosic biomass and hard template at a mass ratio of 1:0.5-2.5 at 25±5°C until uniformly mixed, and then calcining the mixture in a tube furnace at 800±50°C for 1-3 hours under an inert gas atmosphere to obtain a crude product. The tube furnace is heated at a rate of 5-15°C / min, and the inert gas flow rate is 200-300 mL / min. The crude product is acid-washed and washed with water until neutral, and then dried to obtain a crude product. Preferably, the inert gas includes nitrogen (N2) or argon (Ar), the acid wash is hydrochloric acid, and the drying temperature is 80°C. The ball milling process mainly uses balls as a medium to achieve material pulverization through the effects of impact, extrusion, and friction. Specifically, during ball milling, the mass ratio of bamboo powder to basic magnesium carbonate is 1:0.5~2.5, ball milling beads with a size of 5~20 mm and occupying 1 / 3 of the ball milling jar are added, and the ball mill is set to ball mill for 3h±1h, reversed once every 30min (stop for 5min), and ball milled for 3h±1h.

[0016] Furthermore, the hydrothermal synthesis process includes: first adding the metal oxide precursor and hydrochloric acid dropwise to the ethanol solution in proportion and mixing to obtain solution A, adding the biochar substrate to the solution A in proportion and mixing to obtain solution B, then transferring solution B to a hydrothermal reactor, reacting at 180±5°C for 10±1h, then naturally cooling, and washing and drying to obtain the product.

[0017] Furthermore, the mass ratio of the metal oxide precursor solution, hydrochloric acid, and ethanol solution in the solution A is 0.008-0.07:0.007-0.03:1; the mass ratio of the amount of biochar substrate to the amount of ethanol solution in the solution B is 0.007-0.015; the metal oxide precursor includes tetrabutyl titanate (TBOT) or SnCl4·5H2O; preferably, the concentration of the ethanol solution is greater than 99.5%, and the concentration of the hydrochloric acid is 3-12 mol / L.

[0018] Finally, the present invention provides a biochar / metal oxide composite material, which is prepared by the above preparation method.

[0019] The beneficial effects of the present invention are: 1. The application of the biochar / metal oxide composite material provided by the present invention in the elimination of antibiotics uses adsorption and photocatalysis to synergistically and efficiently eliminate high concentrations of antibiotics in water bodies, with a fast elimination rate and high elimination rate.

[0020] 2. The application of the biochar / metal oxide composite material provided by the present invention in the elimination of antibiotics uses a biochar / metal oxide composite material with biological mesoporous carbon as the substrate, which has a large specific surface area and high adsorption efficiency for antibiotics. It is loaded with an appropriate content of metal oxide and can efficiently catalyze the degradation of antibiotics under the action of light, thereby achieving a synergistic effect of adsorption and photocatalysis.

[0021] 3. The present invention provides a method for preparing a biochar / metal oxide composite material. In this method, the biochar substrate is prepared by ball milling lignocellulosic biomass and a hard template to achieve mutual embedding of the raw materials, avoiding the use of organic solvents. Lignocellulosic biomass is a low-cost and widely available raw material, and the use of a hard template provides the foundation for the generation of mesopores.

[0022] 4. The present invention provides a method for preparing a biochar / metal oxide composite material. In this method, the metal oxide is loaded using a hydrothermal method to allow the metal oxide to grow in situ in the pores of the biochar substrate. The process is simple and the loading amount is controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Attachment Figure 1 Schematic diagram of the application principle of the biochar / metal oxide composite material in the elimination of antibiotics in the present invention; Attachment Figure 2 The morphology and elemental analysis diagrams of the biochar / metal oxide composite material Mes / 1.0TiO2 in Example 1 of the present invention are shown; wherein a is a morphology analysis diagram, with a scale of 5 μm; b~e are elemental analysis diagrams, with a scale of 10 μm; Attachment Figure 3 This is a morphology analysis diagram of the BC material in Comparative Example 1; wherein the scale is 2 μm; Attachment Figure 4 Figure 1 is a test diagram for eliminating tetracycline; Figure (a) shows the dispersion effect of different biochar / metal oxide composite materials in tetracycline aqueous solution, and Figure (b) shows the test results of various materials in the examples and comparative examples under light (left) and dark (right) conditions; Attachment Figure 5 The figures are test diagrams of the elimination of ciprofloxacin by various materials in the examples and comparative examples; (a) is the test result under light conditions; (b) is the test result under dark conditions. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. The embodiments mentioned are all implemented based on the technical solutions of the present invention, and detailed implementation processes are given. However, it should be noted that the scope of protection of the present invention is not limited to the following embodiments.

[0026] like Figure 1 As shown, the present invention eliminates antibiotics by utilizing the adsorption of antibiotics by a biochar / metal oxide composite material and synergistic photocatalytic degradation. The high-performance biochar / metal oxide composite material is added proportionally to an aqueous solution of antibiotics. After dispersion, the biochar / metal oxide composite material adsorbs the antibiotics and, under light conditions, degrades the antibiotics into harmless small molecules such as CO2 and H2O, thereby purifying the water environment.

[0027] The present invention adopts a high-performance biochar / metal oxide composite material to eliminate antibiotics. The material uses waste biomass that is widely available and renewable in nature as raw material. First, a hard template method is adopted to prepare a mesoporous biochar substrate, and then a hydrothermal method is combined to uniformly grow metal oxides in the pores of the mesoporous biochar substrate to prepare the material.

[0028] 1. Material Preparation Example 1 (1) At room temperature (25±5℃), 4g of bamboo powder and 4g of basic magnesium carbonate were mixed, and 180g of 8mm ball mill beads were added. The mixture was inverted once every 30min (rested for 5min), and ground for 3h to form a uniform powder sample. The powder sample was placed in a tube furnace, nitrogen (N2) gas was passed through at a flow rate of 200mL / min, and the temperature was increased to 800℃ at a rate of 10℃ / min. The sample was calcined at 800℃ for 2h. After calcination, the sample was stirred overnight in 1mol / L HCl, and then washed with a large amount of water until the pH was neutral. It was dried at 80℃ overnight and collected for use to prepare a mesoporous biochar substrate.

[0029] (2) 30 mL of ethanol (purity approximately 99.5%) was placed in a beaker and stirred. 0.5 mL of 6 mol / L HCl solution and 1.0 mL of tetrabutyl titanate (TBOT) were added dropwise while stirring. Then, 0.3 g of mesoporous biochar substrate was added and stirred for 30 min. The above mixture was transferred to a hydrothermal reactor and hydrothermally reacted at 180°C for 10 h. After natural cooling, it was washed with water five times and dried at 80°C overnight to prepare a biochar / metal oxide composite material, which was labeled Mes / 1.0TiO2.

[0030] Example 2 (1) At room temperature (25±5℃), take 2g of bamboo powder and 2g of basic magnesium carbonate, mix them, add 180g of 8mm ball mill beads, reverse once every 30min (stop for 5min), grind for 3h to form a uniform powder sample. The powder sample is placed in a tube furnace, argon (Ar) gas is introduced at a flow rate of 220mL / min, and the temperature is increased to 750℃ at 5℃ / min. It is calcined at 750℃ for 3.0h. After calcination, the sample is stirred overnight in 0.5mol / L HCl, then washed with a large amount of water until the pH is neutral, dried at 100℃ overnight and collected for use to prepare a mesoporous biochar substrate.

[0031] (2) 20 mL of ethanol (purity approximately 99.5%) was placed in a beaker and stirred. 0.5 mL of 6 mol / L HCl solution and 0.25 mL of tetrabutyl titanate (TBOT) were added dropwise while stirring. Then, 0.3 g of mesoporous biochar substrate was added and stirred for 30 min. The above mixture was transferred to a hydrothermal reactor and hydrothermally reacted at 180°C for 10 h. After natural cooling, it was washed with water 6 times and dried at 80°C overnight to prepare a biochar / metal oxide composite material, which was labeled as Mes / 0.25TiO2.

[0032] Example 3 (1) At room temperature (25±5℃), 3g of bamboo powder and 3g of basic magnesium carbonate were mixed, and 180g of 8mm ball mill beads were added. The mixture was inverted once every 30min (rested for 5min), and ground for 3h to form a uniform powder sample. The powder sample was placed in a tube furnace, nitrogen (N2) gas was introduced at a flow rate of 250mL / min, and the temperature was increased to 830℃ at 8℃ / min. The sample was calcined at 830℃ for 2.5h. After calcination, the sample was stirred overnight in 0.8mol / L HCl, and then washed with a large amount of water until the pH was neutral. The sample was dried at 60℃ overnight and collected for use to prepare a mesoporous biochar-based material.

[0033] (2) 35 mL of ethanol (purity approximately 99.5%) was placed in a beaker and stirred. 0.5 mL of 6 mol / L HCl solution and 0.5 mL of tetrabutyl titanate (TBOT) were added dropwise while stirring. Then, 0.3 g of mesoporous biochar substrate was added and stirred for 30 min. The above mixture was transferred to a hydrothermal reactor and hydrothermally reacted at 180°C for 10 h. After natural cooling, it was washed with water seven times and dried at 100°C overnight to prepare a biochar / metal oxide composite material, which was labeled as Mes / 0.5TiO2.

[0034] Example 4 (1) At room temperature (25±5℃), 5g of bamboo powder and 5g of basic magnesium carbonate were mixed, and 180g of 8mm ball mill beads were added. The mixture was inverted once every 30min (rested for 5min), and ground for 3h to form a uniform powder sample. The powder sample was placed in a tube furnace, and argon (Ar) gas was introduced at a flow rate of 260mL / min. The temperature was raised to 850℃ at 15℃ / min and calcined at 850℃ for 1.5h. After calcination, the sample was stirred overnight in 1.2mol / L HCl, and then washed with a large amount of water until the pH was neutral. The sample was dried at 90℃ overnight and collected for use to prepare a mesoporous biochar-based material.

[0035] (2) 40 mL of ethanol (purity approximately 99.5%) was placed in a beaker and stirred. 0.5 mL of 6 mol / L HCl solution and 2.0 mL of tetrabutyl titanate (TBOT) were added dropwise while stirring. Then, 0.3 g of mesoporous biochar substrate was added and stirred for 30 min. The above mixture was transferred to a hydrothermal reactor and hydrothermally reacted at 180°C for 10 h. After natural cooling, it was washed with water 8 times and dried at 85°C overnight to prepare a biochar / metal oxide composite material, which was labeled as Mes / 2.0TiO2.

[0036] The morphology and elemental analysis test results of the biochar / metal oxide composite material Mes / 1.0TiO2 prepared in Example 1 are as follows: Figure 2The biochar / metal oxide composite material of the present invention is a cross-linked porous structure, forming a 3D framework ( Figure 2 a). After the hydrothermal reaction, TiO2 can be loaded on the surface of the mesoporous biochar substrate to enhance its activity. Elemental analysis shows that the surface of the mesoporous biochar substrate contains three elements: C, O, and Ti, indicating that the metal oxide TiO2 is uniformly co-doped in situ in the carbon skeleton ( Figure 2 b~e).

[0037] The specific surface area, pore type and volume, metal oxide content, etc. of the composite materials prepared in Examples 1 to 4 were characterized and analyzed and measured. The test results are shown in Table 1 below.

[0038] As can be seen from Table 1, in the present invention, a mesoporous biochar photocatalyst carrier is prepared by hard template design, and a metal oxide is controllably grown on its surface by a hydrothermal method. The prepared composite material has both mesopores and metal oxides, and has excellent adsorption and photocatalytic properties.

[0039] Comparative Example 1 The loading of the metal oxide in step (2) of Comparative Example 1 is the same as that in Example 1. The difference from Example 1 is that basic magnesium carbonate is not used in preparing the biochar substrate in step (1). The material prepared in this embodiment is marked as BC.

[0040] The morphology test results of the BC material prepared in Comparative Example 1 are as follows: Figure 3 shown. Figure 3 The results show that since no hard template is used to provide a basis for the formation of mesopores, the BC material is in the form of large particles with a relatively smooth surface. The macroporous structure of the biomass after carbonization can be observed on the surface. These macropores are formed during the growth of the biomass. The specific surface area of the material is 345.02 m 2 / g, micropore specific surface area 218.15m 2 / g, total pore volume 0.184cm 3 / g, the volume of macropores + mesopores is 0.059 cm 3 / g; EDS element analysis of the material showed that no Ti element was detected on the surface of the material.

[0041] Comparative Example 2 The method for preparing the mesoporous biochar substrate in step (1) of Comparative Example 2 is the same as that in Example 1, except that the loading of the metal oxide in step (2) is not performed. The material prepared in this embodiment is labeled Mes.

[0042] The Mes material prepared in Comparative Example 2 was tested and found to have a specific surface area of 1288.34 m 2 / g, micropore specific surface area 853.32 m 2 / g, and a total pore volume of 1.086 cm 3 / g, the volume of macropores + mesopores is 0.721cm 2 / g, and EDS element analysis was performed on the material. The results showed that no Ti element was detected on the surface of the material.

[0043] Comparative Example 3 Comparative Example 3 shows TiO2 prepared using tetrabutyl titanate without the addition of mesoporous biochar. The specific preparation process is as follows: 30 mL of ethanol (approximately 99.5% purity) was placed in a beaker and stirred. 0.5 mL of a 6 mol / L HCl solution and 1.0 mL of tetrabutyl titanate (TBOT) were added dropwise while stirring. The mixture was transferred to a hydrothermal reactor and hydrothermally reacted at 180°C for 10 hours. After cooling naturally, the mixture was washed five times with water and then dried overnight at 80°C to produce the synthesized TiO2, labeled Blank TiO2.

[0044] Comparative Example 4 Comparative Example 4 is a commercial photocatalyst produced by Shanghai Aladdin Biochemical Technology Co., Ltd. Its CAS number is 13463-67-7, and its purity is ≥99%. It is labeled as Commercial TiO2.

[0045] 2. Verification of antibiotic elimination performance of different materials The materials in Examples 1-4 and Comparative Examples 1-4 were applied to the elimination of antibiotics to verify the effectiveness of the different materials in removing antibiotics from water. Application Examples 1 and 2 below provide examples of the elimination of tetracycline antibiotics and fluoroquinolone antibiotics, respectively.

[0046] Application Example 1: Elimination of Tetracycline (1) Sample preparation: 100 mg of the material was dispersed in a quartz beaker containing 100 mL of an aqueous solution of the antibiotic tetracycline (initial concentration Co = 120 mg / L). Two identical samples were prepared and designated as Sample 1 and Sample 2. The antibiotic was commercially available tetracycline, manufactured by Shanghai MacLean Biochemical Technology Co., Ltd., with a CAS number of 60-54-8 and a purity of ≥98%.

[0047] (2) Elimination performance verification: Using a static adsorption experiment, under dark conditions, sample 1 was placed in a tetracycline aqueous solution of a certain concentration. A certain amount of suspension was taken out at intervals of 20 minutes, 25 minutes, 35 minutes, 50 minutes, 65 minutes, 80 minutes, and 115 minutes. After filtration, the concentration of antibiotics in the remaining solution was determined by high-performance liquid chromatography (HPLC) (this concentration is marked as Ce). At the beginning of stirring, UV light was applied. Sample 2 was stirred at the same time, and a certain amount of suspension was taken out at the same intervals during the stirring process. After filtration, the concentration of antibiotics in the remaining solution was determined by high-performance liquid chromatography. The difference between the removal amount of antibiotics by adsorption and photocatalysis under light and the removal amount of antibiotics by adsorption under dark conditions was compared.

[0048] (3) Verification of tetracycline self-degradation: Two 100 mL portions of tetracycline aqueous solution (initial concentration Co = 120 mg / L) were placed in two quartz beakers without adding any other materials. These were designated as Sample 3 and Sample 4, respectively, for verification of tetracycline self-degradation. The test of Sample 3 was performed with reference to Sample 1, and the test of Sample 4 was performed with reference to Sample 4. The tetracycline self-degradation sample was labeled Blank TC.

[0049] The test results of tetracycline elimination in water are as follows Figure 4 As shown. Figure 4 As can be seen from Figure a, the biochar / metal oxide composite material of the present invention can be uniformly dispersed in the tetracycline aqueous solution. Figure 4As shown in Figure b, tetracycline has poor self-degradation ability in water and cannot be eliminated naturally. It requires the use of materials with degradation or adsorption effects on it to achieve its elimination. Compared with the various materials in the comparative examples, the materials in the examples of the present invention can all effectively eliminate tetracycline in water. Specifically, under dark conditions, the elimination performance of each material showed significant differences at 20 minutes, and the gap became increasingly larger as time went on. When the time was extended to 35 minutes, the elimination rate of tetracycline by the materials in the examples increased significantly, reaching the elimination effect of the various materials in the comparative examples at 115 minutes. After the time was extended to 80 minutes, the elimination rate of tetracycline by the materials in the examples reached over 50%, and could reach as high as over 90%. Under light conditions, the elimination performance of each material showed the same trend of change over time as the elimination performance under dark conditions. Because the materials adsorb the antibiotics and cooperate with the photocatalytic degradation under light conditions, their elimination rates were higher at the same exposure time, reaching up to 100%, with Mes / 1.0TiO2 having the best elimination effect. In the various biochar / metal oxide composites provided by this invention, the biochar's excellent electron transfer properties promote the separation and transfer of photogenerated charge carriers. Its mesoporous structure rapidly adsorbs pollutants and enhances contact between them and the metal oxide, thereby improving photocatalytic efficiency and achieving the synergistic elimination of antibiotics through adsorption and photocatalysis. This indicates that mesopores play a crucial role in the adsorption and photocatalytic removal of pollutants.

[0050] Application Example 2: Elimination of Ciprofloxacin In order to further verify the elimination ability of biochar / metal oxide composite materials on different antibiotics, this application example used ciprofloxacin aqueous solution as the elimination object to carry out relevant experiments.

[0051] This application example is the same as the elimination performance verification process in step (2) of application example 1. The self-degradation ability verification of ciprofloxacin is the same as step (3). The ciprofloxacin self-degradation sample is marked as Blank CI. The difference is that the antibiotic ciprofloxacin aqueous solution is used in the sample preparation in step (1). The initial concentration of the ciprofloxacin aqueous solution is Co = 100 mg / L. The antibiotic is commercially available ciprofloxacin, which is manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd. Its CAS model is 85721-33-1 and its purity is ≥98%.

[0052] Elimination of ciprofloxacin in water test results Figure 5 As shown in the figure, ciprofloxacin has poor self-degradation ability in water and cannot be eliminated naturally. It needs to be eliminated with the help of materials that have degradation or adsorption effects on it. The elimination performance of various materials for ciprofloxacin has the same trend as that for tetracycline, and also shows good elimination effect. Specifically, from Figure 5 As can be seen in a, the biochar / metal oxide composite materials all showed good ciprofloxacin removal effects under light. Among them, Mes / 1.0 TiO2 had the highest removal rate of ciprofloxacin, which was mainly attributed to its strong adsorption effect on ciprofloxacin. Under the same experimental conditions, the removal of ciprofloxacin by the biochar / metal oxide composite materials under light irradiation was significantly higher than that of the corresponding samples under no light irradiation. It can be seen that ultraviolet light irradiation has a certain promoting effect on the degradation of ciprofloxacin by the composite materials, especially the samples loaded with TiO2. This shows that the TiO2 in the composite material exhibits strong photocatalytic activity for the photocatalytic degradation of ciprofloxacin. Mesoporous biochar not only helps the distribution and stability of metal oxides, but also accelerates the transfer of photogenerated electrons. The test results of ciprofloxacin removal under dark conditions are shown in Figure 2. Figure 5 b. The results indicate that mesoporous biochar plays an important role in the adsorption and photocatalytic removal of pollutants. The present invention utilizes adsorption and photocatalysis to synergistically and efficiently remove multiple antibiotics from water.

[0053] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. Application of a biochar / metal oxide composite material in antibiotic elimination.

2. The use according to claim 1, characterized in that The biochar / metal oxide composite material is dispersed in the antibiotic aqueous solution in proportion, and the antibiotic can be eliminated under light conditions; the mass ratio of the antibiotic aqueous solution to the biochar / metal oxide composite material is 1000:0.8~1.

2.

3. The use according to claim 1, characterized in that The substrate of the biochar / metal oxide composite material is a biochar substrate, the surface of the biochar substrate is loaded with the metal oxide, and the loading amount of the metal oxide is in the range of 15 wt % to 60 wt %.

4. The use according to claim 3, characterized in that The biochar substrate is a mesoporous carbon material, the metal oxide includes TiO2 or SnO2; the antibiotics include tetracycline antibiotics, fluoroquinolone antibiotics or sulfonamide antibiotics; the tetracycline antibiotics include tetracycline, the fluoroquinolone antibiotics include ciprofloxacin or enrofloxacin, and the sulfonamide antibiotics include sulfadiazine.

5. A method for preparing the biochar / metal oxide composite material according to any one of claims 1 to 4, characterized in that: First, lignocellulosic biomass is used as a raw material and mixed with a hard template in proportion, and then pyrolyzed to prepare a biochar substrate; then, metal oxides are in situ loaded on the surface of the biochar substrate through hydrothermal synthesis.

6. The preparation method according to claim 5, wherein The lignocellulosic biomass includes straw, bamboo or peanut shell, and the hard template includes basic magnesium carbonate, magnesium oxide or slag.

7. The preparation method according to claim 5, wherein The preparation process of the biochar substrate includes: ball milling the lignocellulosic biomass and the hard template at a mass ratio of 1:0.5-2.5 at 25±5°C, calcining at 800±50°C for 1-3 hours under an inert gas atmosphere to obtain a crude product; the crude product is acid-washed and washed with water until neutral, and then dried.

8. The preparation method according to claim 5, wherein The hydrothermal synthesis process includes: first, adding the metal oxide precursor and hydrochloric acid to the ethanol solution in proportion and mixing to obtain solution A; adding the biochar substrate to the solution A in proportion and mixing to obtain solution B; then, reacting solution B at 180±5°C for 10±1h, cooling the solution, washing with water, and drying the solution.

9. The preparation method according to claim 7, wherein The mass ratio of the metal oxide precursor solution, hydrochloric acid, and ethanol solution in the solution A is 0.008-0.07:0.007-0.03:1; the mass ratio of the biochar substrate to the ethanol solution in the solution B is 0.007-0.015; and the metal oxide precursor includes tetrabutyl titanate or SnCl4·5H2O.

10. A biochar / metal oxide composite material, characterized in that: It is prepared by the preparation method according to any one of claims 5 to 9.

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