Magnetic composite photocatalyst for removing antibiotics as well as preparation method and application of magnetic composite photocatalyst

Abstract

The invention relates to the technical field of photocatalysts, in particular to a magnetic composite photocatalyst for removing antibiotics as well as a preparation method and application of the magnetic composite photocatalyst. The preparation method comprises the following steps: mixing choline chloride, glycerol, ethanol, a magnesium source, an iron source and citric acid, and carrying out complex reaction to obtain sol; adjusting the pH value of the sol, and then heating to form gel; igniting the gel to obtain a precursor; calcining the precursor to obtain the magnetic composite photocatalyst; in the mixing process, the molar ratio of the magnesium element in the magnesium source to the iron element in the iron source is (1-1.6): (1.8-2.4); the molar ratio of choline chloride to glycerol to ethanol is (0.5-1.5): (1.5-2.5): (0.1-0.3). By adopting the method, the magnetic composite photocatalyst composed of magnesium ferrite, magnesium oxide and ferric oxide can be prepared, and the magnetic composite photocatalyst has a relatively good treatment effect on antibiotics, and is high in removal rate and relatively short in removal time.

Description

Technical Field

[0001] The invention relates to the technical field of photocatalysts, and in particular to a magnetic composite photocatalyst for removing antibiotics, and a preparation method and application thereof. Background Art

[0002] Antibiotic wastewater mainly comes from hospitals, pharmaceutical industry, animal husbandry, aquaculture and other fields. Antibiotic wastewater is a new pollutant wastewater with biological toxicity, environmental persistence and accumulation. BOD5 / COD is usually less than 0.1. Traditional methods cannot effectively degrade antibiotic wastewater. Advanced oxidation technology is needed for pretreatment to increase the BOD5 / COD of the wastewater to above 0.3 to improve its biodegradability, and then use traditional methods for efficient treatment. Photocatalytic advanced oxidation technology can pretreat and deeply treat antibiotic wastewater, and the theoretical treatment cost is very low, which has received widespread attention in recent years.

[0003] Photocatalytic technology is an emerging and effective technical means to treat organic matter. Its mechanism of action is to directly use sunlight to irradiate semiconductor materials, induce strong oxidizing and reducing substances, and directly react with pollutants in water to convert organic matter in water into non-toxic small molecules. Photocatalyst materials are mostly metal oxide or sulfide semiconductors. Their structure consists of a lower energy valence band and a higher energy conduction band. There is a band gap between the valence band and the conduction band. When photons with energy higher than the band gap width of the semiconductor irradiate the semiconductor, the valence band electrons undergo inter-band transitions from the valence band to the conduction band, generating positively charged photoinduced holes and negatively charged photogenerated electrons. The strong oxidizing properties of photoinduced holes and the reducing properties of photogenerated electrons trigger a series of photocatalytic reactions, which can be used to treat organic pollutants such as antibiotics in sewage.

[0004] Tetracycline is a typical antibiotic commonly used in humans and animals. In different water environments, the half-life of tetracycline is different, and the natural degradation time is in the range of 4.5 to 180 days. Especially under acidic conditions, tetracycline is very stable and has strong accumulation. The accumulation effect will cause water pollution on the one hand, and on the other hand, it will change the microbial environment in the water or soil, causing the production of antibiotic-resistant pathogens, which will then enter the human body through drinking water or the food chain. Therefore, the rapid degradation of tetracycline antibiotics and the reduction of their accumulation effect will be of great significance.

[0005] Ciprofloxacin is one of the fluoroquinolone antibiotics and is also the most widely used chemical drug antibiotic in the world. There are three generations of fluoroquinolone antibiotics. The first generation of fluoroquinolone antibiotics is nalidixic acid. Through scientific research experiments, the structure of nalidixic acid has been continuously optimized and improved, and the second and third generations of fluoroquinolone antibiotics have been successfully generated. Common second-generation fluoroquinolone antibiotics include ciprofloxacin, enrofloxacin and clinafloxacin. Among them, ciprofloxacin has good antibacterial and antibacterial effects, and has good antibacterial effects on Pseudomonas aeruginosa, Enterobacter, Haemophilus influenzae, Legionella, Neisseria gonorrhoeae, Streptococcus, and Staphylococcus aureus. Ciprofloxacin blocks bacterial proliferation by destroying cell replication in bacteria, which can achieve effective antibacterial effects. Due to the widespread use of ciprofloxacin in medical and aquaculture industries, ciprofloxacin drug residues have appeared in water, soil, and even in animals and plants. Therefore, the degradation and removal of ciprofloxacin is of great significance.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a method for preparing a magnetic composite photocatalyst for removing antibiotics. The method can be used to prepare a magnetic composite photocatalyst composed of magnesium ferrite, magnesium oxide and ferric oxide. The magnetic composite photocatalyst has a good treatment effect on antibiotics, a high removal rate, and a short removal time.

[0008] The second object of the present invention is to provide a magnetic composite photocatalyst for removing antibiotics, wherein the magnetic composite photocatalyst has a high removal rate for antibiotics such as tetracycline and ciprofloxacin and a short removal time.

[0009] The third object of the present invention is to provide an application of a magnetic composite photocatalyst for removing antibiotics.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] The present invention first provides a method for preparing a magnetic composite photocatalyst for removing antibiotics, comprising the following steps:

[0012] Choline chloride, glycerol, ethanol, a magnesium source, an iron source and citric acid are mixed and subjected to complexation reaction to obtain a sol; the pH of the sol is adjusted, and then heated to form a gel; the gel is ignited to obtain a precursor; and the precursor is calcined to obtain the magnetic composite photocatalyst.

[0013] During the mixing process, the molar ratio of the magnesium element in the magnesium source to the iron element in the iron source is 1-1.6:1.8-2.4.

[0014] The molar ratio of the choline chloride, the glycerol and the ethanol is 0.5-1.5:1.5-2.5:0.1-0.3.

[0015] Furthermore, the ratio of the molar amount of the citric acid to the molar amount of the magnesium element in the magnesium source is 1.8 to 4:1.

[0016] Furthermore, the ratio of the sum of the volumes of the choline chloride, the glycerol and the ethanol to the molar amount of the magnesium element in the magnesium source is 15-85 mL:1 mol.

[0017] Furthermore, the temperature of the complexation reaction is 40-90°C.

[0018] Furthermore, the pH of the sol is adjusted to 6.5-9.5.

[0019] Furthermore, the calcination temperature is 400-900°C.

[0020] Furthermore, the calcination holding time is ≥1h.

[0021] Furthermore, the calcination further includes the steps of washing and drying.

[0022] The present invention further provides a magnetic composite photocatalyst for removing antibiotics, which is mainly prepared by the preparation method of the magnetic composite photocatalyst for removing antibiotics. The magnetic composite photocatalyst for removing antibiotics comprises magnesium ferrite, magnesium oxide and ferric oxide.

[0023] The invention also provides application of the magnetic composite photocatalyst for removing antibiotics in removing antibiotics, wherein the antibiotics include tetracycline and ciprofloxacin.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention provides a method for preparing a magnetic composite photocatalyst for removing antibiotics. The method can be used to prepare a magnetic composite photocatalyst composed of magnesium ferrite, magnesium oxide and ferric oxide. The magnetic composite photocatalyst has a good treatment effect on antibiotics, a high removal rate, and a short removal time.

[0026] (2) The method for preparing the magnetic composite photocatalyst for removing antibiotics provided by the present invention has magnetism, can be recovered and reused multiple times by applying an external magnetic field, and is environmentally friendly and energy-saving.

[0027] (3) The preparation method of the magnetic composite photocatalyst for removing antibiotics provided by the present invention has mild conditions, short time consumption and excellent effect for the photocatalysis of antibiotics such as tetracycline and ciprofloxacin.

[0028] (4) The preparation method of the magnetic composite photocatalyst for removing antibiotics provided by the present invention is easy to operate, suitable for large-scale production, has low raw material cost, and the particle size distribution of the obtained product is uniform and the product added value is high. The magnetic composite photocatalyst prepared by this method can be widely used in the treatment of antibiotic wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 The XRD diagram of the magnetic composite photocatalyst prepared in Example 4 provided by the present invention;

[0031] Figure 2 A curve diagram showing the change in the removal rate of the tetracycline solution by the magnetic composite photocatalyst prepared in Example 4 provided by the present invention as a function of the treatment time;

[0032] Figure 3 A curve diagram showing the change in removal rate of ciprofloxacin solution by the magnetic composite photocatalyst prepared in Example 4 provided by the present invention as a function of treatment time;

[0033] Figure 4 A comparison chart of the removal rates of tetracycline solution by the magnetic composite photocatalyst prepared in Example 4 of the present invention after the first photocatalysis and three repeated recycling of tetracycline solution;

[0034] Figure 5 This is a comparison chart of the removal rates of ciprofloxacin solution after the first photocatalysis of the magnetic composite photocatalyst prepared in Example 4 provided by the present invention and after three repeated recycling. DETAILED DESCRIPTION

[0035] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0036] If there is no special explanation, in the present invention, "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", "the third", "the fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0037] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0038] If there is no special explanation, in the present invention, "one or more" or "at least one" refers to any one, any two or more of the listed items. Among them, "several" refers to any two or more of the listed items.

[0039] In a first aspect, the present invention provides a method for preparing a magnetic composite photocatalyst for removing antibiotics, comprising the following steps: mixing choline chloride, glycerol, ethanol, a magnesium source, an iron source and citric acid, and performing a complexation reaction to obtain a sol. Adjusting the pH of the sol, and then heating it to form a viscous gel. Ignite the gel to fully burn it, and obtain a precursor after the combustion ends. Calcinate the precursor, and obtain the magnetic composite photocatalyst after cooling.

[0040] Wherein, during the mixing process, the molar ratio of the magnesium element in the magnesium source to the iron element in the iron source is 1 to 1.6 (including but not limited to any one of 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 or any range between two of them): 1.8 to 2.4 (including but not limited to any one of 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 or any range between two of them); values ​​or any range between them), for example, 1.0:1.8, 1.0:2.0, 1.0:2.2, 1.0:2.4, 1.2:1.8, 1.2:2.0, 1.2:2.2, 1.2:2.4, 1.4:1.8, 1.4:2.0, 1.4:2.2, 1.4:2.4, 1.6:1.8, 1.6:2.0, 1.6:2.2, 1.6:2.4, etc.

[0041] The molar ratio of the choline chloride, the glycerol and the ethanol is 0.5-1.5 (including but not limited to any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any range between two of them): 1.5-2.5 (including but not limited to any one of 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5) point value or any range value between two of them): 0.1~0.3 (including but not limited to any one of 0.1, 0.2, 0.3 or any range value between two of them), for example 0.5:1.5:0.1, 1:1.5:0.1, 1.5:1.5:0.1, 0.5:2:0.2, 1:2:0.2, 1.5:2:0.2, 0.5:2.5:0.3, 1:2.5:0.3, 1.5:2.5:0.3, etc.

[0042] The method can be used to prepare a magnetic composite photocatalyst composed of magnesium ferrite, magnesium oxide and ferric oxide. The magnetic composite photocatalyst has a good treatment effect on antibiotics, a high removal rate and a short removal time.

[0043] In addition, the present invention adopts the sol-gel-ignition method for reaction, which has the advantages of simple operation, short reaction time, low sintering temperature, uniform particle size distribution of the obtained product, easy control of the reaction process, low cost, stable process and easy repeatability.

[0044] Specifically, the present invention uses a specific choline chloride-propylene glycol-ethanol mixed solution as a solvent, so that the anions and cations in the mixture are fully mixed with the metal ions in the mixed solution through the electrostatic force, and then the iron salt and the metal ions are evenly dispersed in the process of sol-gel formation, which is beneficial to the formation of the nanoparticles of the precursor, and the particles are finer and more uniform, thereby improving the static magnetic properties, stability, and surface active center content of the magnetic composite photocatalyst.

[0045] In some specific embodiments, choline chloride, glycerol, and ethanol are mixed to form a solvent. A magnesium source, an iron source, and citric acid are then added to the solvent, mixed, and subjected to a complex reaction to obtain a sol. The pH of the sol is then adjusted, and the sol is heated to form a gel. By adjusting the pH of the sol, the dissociation form of citric acid, the morphology and spatial network structure of the gel, and the dispersibility of metal ions can be controlled, thereby improving the microstructure and performance of the material. In addition, the ethanol in the solvent can also accelerate the reaction speed after ignition, making the combustion more complete, which is beneficial to promoting the solid phase reaction of the precursor calcination process.

[0046] In some specific embodiments, the preparation method of the magnetic composite photocatalyst for removing antibiotics specifically includes: first mixing choline chloride, propylene glycol, and ethanol evenly, then adding a magnesium source and an iron source thereto, stirring for a period of time, adding citric acid thereto to carry out a complex reaction, and after reacting for a period of time, adding an ammonia solution or a sodium hydroxide solution thereto to adjust the pH of the reaction system to obtain a sol; heating the sol to gradually form a gel, and igniting the gel to obtain a precursor; calcining the precursor and cooling it to obtain a magnetic composite photocatalyst.

[0047] It is understandable that the ratio of choline chloride, glycerol and ethanol and the ratio of metal elements are important factors affecting the removal rate of antibiotics. The above ratio can ensure a higher removal rate.

[0048] In some specific embodiments, the magnesium source includes a magnesium-containing compound, such as magnesium nitrate, but is not limited thereto.

[0049] In some specific embodiments, the iron source includes an iron-containing compound, such as ferric nitrate, but is not limited thereto.

[0050] In order to further improve the degradation effect of the magnetic composite photocatalyst on antibiotics, increase the removal rate, and shorten the removal time, the present invention optimizes the addition amount of citric acid and parameters such as temperature, pH value and time during the preparation process as follows.

[0051] In some specific embodiments, the ratio of the molar amount of citric acid to the molar amount of magnesium in the magnesium source is 1.8 to 4:1, including but not limited to any point value of 1.8:1, 1.9:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or a range value between any two of them.

[0052] Among them, citric acid mainly acts as a buffer in the solvent, which is beneficial to adjust the pH of the reaction system and promote the formation of sol. Secondly, citric acid is an organic acid, and the citrate ions contained in it can form complexes with metal ions. Due to the chelation effect, the complex has a certain stability, thereby improving the structure, spatial network, particle size and distribution of the material.

[0053] In some specific embodiments, the ratio of the sum of the volumes of the choline chloride, the glycerol and the ethanol to the molar amount of the magnesium element in the magnesium source is 15 to 85 (eg, 20, 30, 40, 50, 60 or 70) mL: 1 mol.

[0054] In some specific embodiments, the temperature of the complexation reaction is 40-90°C, including but not limited to any point value of 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or a range between any two of them.

[0055] In some specific embodiments, the pH of the sol is adjusted to 6.5-9.5, including but not limited to any point value of 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or a range of values ​​between any two of them.

[0056] In some specific embodiments, the calcination temperature is 400-900°C, including but not limited to any one of 400°C, 500°C, 600°C, 700°C, 800°C, 900°C or a range between any two of them.

[0057] In some specific embodiments, the calcination holding time is ≥1h, including but not limited to any one of 1h, 3h, 5h, 6h, 8h, 10h, 12h, 15h, 20h, 24h or a range between any two of them.

[0058] In some specific embodiments, the calcination further comprises the steps of water washing and drying.

[0059] In a second aspect, the present invention provides a magnetic composite photocatalyst for removing antibiotics, which is mainly prepared by the preparation method of the magnetic composite photocatalyst for removing antibiotics, wherein the magnetic composite photocatalyst for removing antibiotics includes magnesium ferrite (MgFe2O4), magnesium oxide and ferric oxide.

[0060] The magnetic composite photocatalyst has a good treatment effect on antibiotics such as tetracycline and ciprofloxacin, with a high removal rate and a short removal time.

[0061] In addition, the magnetic composite photocatalyst has magnetism and can be recovered and reused multiple times through an external magnetic field, which is environmentally friendly and energy-saving.

[0062] In a third aspect, the present invention provides the use of the magnetic composite photocatalyst for removing antibiotics in removing antibiotics, wherein the antibiotics include but are not limited to tetracycline and ciprofloxacin.

[0063] The magnetic composite photocatalyst for removing antibiotics provided by the present invention has mild conditions for adsorbing antibiotics such as tetracycline and ciprofloxacin, short time consumption, excellent effect, and the magnetic composite photocatalyst is recyclable.

[0064] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0065] Example 1

[0066] The preparation method of the magnetic composite photocatalyst for removing antibiotics provided in this embodiment comprises the following steps: choline chloride, glycerol, and ethanol are mixed and stirred in a molar ratio of 1:2:0.1 to obtain a choline chloride-glycerol-ethanol solution. 30 mL of choline chloride-glycerol-ethanol solution is mixed with 2 mol of ferric nitrate, 1 mol of magnesium nitrate, and 3 mol of citric acid weighed in advance, and a complex reaction is carried out at 60°C to obtain a sol. The pH value of the sol is adjusted to 7.5 with an ammonia solution, and then continuously heated to form a viscous gel. The gel is ignited to fully burn, and a precursor is obtained after the reaction is completed. The precursor is calcined at 500°C for 5 hours, cooled, washed with water, and dried to obtain a magnetic composite photocatalyst for removing antibiotics.

[0067] Example 2

[0068] The preparation method of the magnetic composite photocatalyst for removing antibiotics provided in this embodiment is basically the same as that in Embodiment 1, except that the molar ratio of choline chloride: glycerol: ethanol is replaced with 1.2: 1.8: 0.15.

[0069] Example 3

[0070] The preparation method of the magnetic composite photocatalyst for removing antibiotics provided in this embodiment is basically the same as that in Embodiment 1, except that the pH value of the sol is adjusted to 8.5.

[0071] Example 4

[0072] The preparation method of the magnetic composite photocatalyst for removing antibiotics provided in this embodiment is basically the same as that in Example 1, except that the precursor is calcined at 700° C. for 2.5 h.

[0073] Example 5

[0074] The preparation method of the magnetic composite photocatalyst for removing antibiotics provided in this embodiment is basically the same as that in Example 1, except that the complexation reaction is carried out at 45°C.

[0075] Example 6

[0076] The preparation method of the magnetic composite photocatalyst for removing antibiotics provided in this embodiment is basically the same as that in Example 1, except that the addition amount of magnesium nitrate is replaced by 1.2 mol, the addition amount of citric acid is replaced by 3.4 mol, and the calcination holding time is replaced by 3 h.

[0077] Example 7

[0078] The preparation method of the magnetic composite photocatalyst for removing antibiotics provided in this embodiment is basically the same as that in Example 1, except that the amount of magnesium nitrate added is replaced by 1.4 mol, the amount of citric acid added is replaced by 3.2 mol, and the molar ratio of choline chloride: glycerol: ethanol is replaced by 1.2:2.5:0.3.

[0079] Comparative Example 1

[0080] The preparation method of the photocatalyst provided in this comparative example is basically the same as that of Example 1, except that glycerol is replaced by an equal molar amount of ethanol, that is, glycerol is not added.

[0081] Comparative Example 2

[0082] The preparation method of the photocatalyst provided in this comparative example is substantially the same as that of Example 1, except that choline chloride is replaced by an equal molar amount of glycerol, that is, choline chloride is not added.

[0083] Comparative Example 3

[0084] The preparation method of the photocatalyst provided in this comparative example is basically the same as that of Example 1, except that the choline chloride-glycerol-ethanol solution is replaced with an equal volume of water, that is, choline chloride, glycerol and ethanol are not added.

[0085] Comparative Example 4

[0086] The photocatalyst provided in this comparative example is ferric oxide.

[0087] Comparative Example 5

[0088] The photocatalyst provided in this comparative example is magnesium ferrite.

[0089] Experimental example

[0090] The magnetic composite photocatalysts prepared in the above embodiments and the photocatalysts prepared in the comparative examples were respectively used to carry out antibiotic (tetracycline and ciprofloxacin) degradation tests, and the photocatalysts were recovered after the antibiotic degradation tests were completed. The removal rate and recovery rate of the antibiotics by each group of photocatalysts were calculated. The results are shown in Table 1. Figure 4 , Figure 5 shown.

[0091] Among them, the test method of the antibiotic degradation test is as follows: 100 ml of 10 mg / L tetracycline solution and 100 ml of 10 mg / L ciprofloxacin solution are respectively transferred, the initial concentration of each antibiotic solution is measured, and the weighed photocatalyst (100 mg) is added to each antibiotic solution, and illumination (40 W visible light) and stirring treatment are started, and timing is started; antibiotic solution (5 ml) is taken every 30 minutes, and after centrifugation and magnetic separation, the concentration of the supernatant is measured to examine its change pattern over time; when the supernatant concentration no longer changes with the removal time, the removal rate of each photocatalyst for the antibiotic solution is calculated, and the magnetic composite photocatalyst is separated by a magnet, and then the photocatalyst is recovered and regenerated by alternating washing with anhydrous ethanol and distilled water. After drying, the composite photocatalyst is repeatedly used for photocatalytic degradation of antibiotics experiments, and the antibiotic removal rate of each photocatalytic experiment is calculated.

[0092] Table 1 Removal rate of antibiotic solution by each photocatalyst

[0093]

[0094]

[0095] It can be seen from Table 1 that the magnetic composite photocatalysts prepared in each embodiment have a high removal rate for tetracycline and ciprofloxacin, while the photocatalysts in each comparative example have a low removal rate for tetracycline and ciprofloxacin. Among them, the magnetic composite photocatalyst prepared in Example 4 has a removal rate of up to 74% for tetracycline solution and a removal rate of up to 99.8% for ciprofloxacin solution.

[0096] In addition, if Figure 1 Shown is the XRD diagram of the magnetic composite photocatalyst prepared in Example 4 provided by the present invention.

[0097] like Figure 2 FIG. 4 is a graph showing the change in removal rate of the tetracycline solution by the magnetic composite photocatalyst prepared in Example 4 of the present invention as a function of treatment time; Figure 3 The figure shows a curve of the change of the removal rate of ciprofloxacin solution by the magnetic composite photocatalyst prepared in Example 4 provided by the present invention as a function of the treatment time.

[0098] like Figure 4 The figure shows the comparison of the removal rate of tetracycline solution by the magnetic composite photocatalyst prepared in Example 4 of the present invention after the first photocatalysis and three repeated recycling. Figure 5 The figure shows the comparison of the removal rates of ciprofloxacin solution by the first photocatalysis of the magnetic composite photocatalyst prepared in Example 4 of the present invention and by repeated recycling three times.

[0099] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a magnetic composite photocatalyst for removing antibiotics, characterized in that: The steps include: The steps of mixing choline chloride, glycerol, ethanol, a magnesium source, an iron source and citric acid and performing a complexation reaction to obtain a sol; adjusting the pH of the sol and then heating it to form a gel; igniting the gel to obtain a precursor; and calcining the precursor to obtain the magnetic composite photocatalyst; During the mixing process, the molar ratio of the magnesium element in the magnesium source to the iron element in the iron source is 1-1.6:1.8-2.4; The molar ratio of the choline chloride, the glycerol and the ethanol is 0.5-1.5:1.5-2.5:0.1-0.

3.

2. The method for preparing the magnetic composite photocatalyst for removing antibiotics according to claim 1, characterized in that: The ratio of the molar amount of the citric acid to the molar amount of the magnesium element in the magnesium source is 1.8 to 4:

1.

3. The method for preparing the magnetic composite photocatalyst for removing antibiotics according to claim 1, characterized in that: The ratio of the sum of the volumes of the choline chloride, the glycerol and the ethanol to the molar amount of the magnesium element in the magnesium source is 15-85 mL:1 mol.

4. The method for preparing the magnetic composite photocatalyst for removing antibiotics according to claim 1, characterized in that: The temperature of the complexation reaction is 40-90°C.

5. The method for preparing the magnetic composite photocatalyst for removing antibiotics according to claim 1, characterized in that: The pH of the sol is adjusted to 6.5-9.

5.

6. The method for preparing the magnetic composite photocatalyst for removing antibiotics according to claim 1, characterized in that: The calcination temperature is 400-900°C.

7. The method for preparing the magnetic composite photocatalyst for removing antibiotics according to claim 1, characterized in that: The calcination holding time is ≥1h.

8. The method for preparing the magnetic composite photocatalyst for removing antibiotics according to claim 1, characterized in that: The calcination step further includes water washing and drying steps.

9. A magnetic composite photocatalyst for removing antibiotics, characterized in that: The invention is mainly prepared by the preparation method of the magnetic composite photocatalyst for removing antibiotics as claimed in any one of claims 1 to 8, wherein the magnetic composite photocatalyst for removing antibiotics comprises magnesium ferrite, magnesium oxide and ferric oxide.

10. Use of the magnetic composite photocatalyst for removing antibiotics as claimed in claim 9 in removing antibiotics, characterized in that: The antibiotics include tetracycline and ciprofloxacin.

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