A persulfate catalyst, a preparation method and application thereof

Abstract

The application discloses a persulfate catalyst and a preparation method and application thereof. The preparation method comprises a calcination treatment step, and the calcination treatment comprises the following steps: first calcination, first cooling, second calcination after temperature rising, second cooling, third calcination after temperature rising, third cooling, and fourth calcination after temperature rising; and the temperature of the last calcination is higher than that of the previous calcination. The pore structure of the obtained catalyst can be enriched through multiple high-temperature calcination and cooling treatment; meanwhile, the stability of the catalyst can be improved by the fact that the temperature of the last calcination is higher than that of the previous calcination.

Description

Technical Field

[0001] The invention belongs to the technical field of traditional Chinese medicine, and specifically relates to a persulfate catalyst and a preparation method and application thereof. Background Art

[0002] Sulfamethoxazole (SMX) is a typical synthetic broad-spectrum antibiotic commonly used to treat bacterial infections, particularly in aquaculture and livestock farming. Following use, only a small fraction of SMX is metabolized or absorbed by living systems, with the majority entering wastewater treatment plants. Due to its stable chemical properties, SMX is difficult to degrade using traditional activated sludge processes. Therefore, there is a need to develop an efficient water treatment process for SMX.

[0003] In recent years, persulfate-based advanced oxidation processes have become an important means of treating organic pollutants in wastewater. The activation of persulfate generates a large amount of sulfate (·SO4-). Compared to hydroxyl radicals (·OH), sulfate (·SO4-) exhibits enhanced selectivity, superior redox potential, and longer lifetime, thereby promoting the effective degradation of pollutants in aquatic environments. The use of transition metal ion-doped materials to catalyze persulfate is considered an effective method for generating free radicals. As a typical perovskite oxide (ABO3) and a good heterogeneous catalyst, BiFeO3 exhibits excellent magnetic properties and acid and alkali resistance (see Non-Patent Literature 1). Under ultrasonic excitation, it can catalyze persulfate by separating electrons and holes. Doping is an effective method for modifying the structure of existing catalysts, making it widely used in catalytic degradation technologies. The properties of perovskite materials can be modified by doping with ions to improve the activity of existing catalysts. Ion doping enhances the catalytic activity of the material. However, doped materials often suffer from secondary contamination caused by metal ion outflow and low material reuse efficiency (see Non-Patent Literature 2). Therefore, it is necessary to explore stable, efficient, reusable doping materials that can be used multiple times without additional ultrasound to excite persulfate, which is one of the key issues that need to be addressed in the field of antibiotic wastewater treatment.

[0004] Non-patent literature 1: Matzek, L. Wan and K. E. Carter (2016). "Activated persulfate for organic chemical degradation: A review." Chemosphere 151: 178-188.

[0005] Non-patent literature 2: Zhu, J., L. Zhang, J. Liu, S. Zhong, P. Gao and J. Shen (2022). "Trichloroethylene remediation using zero-valent iron with kaolin clay, activated carbon and bacteria." Water Research 226:119186. Summary of the Invention

[0006] 1. Problem to be solved

[0007] One of the objectives of the present invention is to provide a persulfate catalyst and a preparation method thereof, wherein the persulfate catalyst has an excellent degradation effect on sulfamethoxazole.

[0008] 2. Technical solution

[0009] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0010] According to the purpose of the present invention, the first aspect of the present invention provides a method for preparing a persulfate catalyst, comprising the steps of:

[0011] S1. preparing a solution containing a bismuth source and an iron source;

[0012] S2, adding a cerium source and nitric acid to the solution;

[0013] S3, treating the solution at 60° C. to 75° C. for 1.5 to 2.5 hours; then treating the solution at 120° C. to 130° C. for 3 to 7 hours to form a gel, and drying and grinding the solution to obtain a solid powder;

[0014] S4, calcining the solid powder;

[0015] The calcination process includes: a first calcination, a second calcination after heating, a third calcination after heating, and a fourth calcination after heating;

[0016] Wherein, the temperature of any calcination treatment is 200-500° C., and the calcination time of each treatment is 10-90 minutes.

[0017] According to the method for preparing a persulfate catalyst of any embodiment of the first aspect of the present invention, the temperature of the first calcination is lower than the temperature of the second calcination, the temperature of the second calcination is lower than the temperature of the third calcination, and the temperature of the third calcination is lower than the temperature of the fourth calcination.

[0018] According to the method for preparing a persulfate catalyst in any embodiment of the first aspect of the present invention, the

[0019] First calcination: temperature is 230℃~260℃; time is 20min~60min;

[0020] Second calcination: temperature is 280℃~320℃; time is 20min~60min;

[0021] The third calcination: temperature is 380℃~420℃; time is 30min~70min;

[0022] The fourth calcination: temperature is 480℃~530℃; time is 30min~70min.

[0023] According to the method for preparing a persulfate catalyst of any embodiment of the first aspect of the present invention, the calcination treatment further comprises: a first cooling, a second cooling, and a third cooling;

[0024] That is, the calcination process includes: a first calcination, a first cooling, a second calcination after heating, a second cooling, a third calcination after heating, a third cooling, and a fourth calcination after heating;

[0025] Wherein, the temperature of any of the cooling steps is 100-350°C.

[0026] According to the method for preparing a persulfate catalyst of any embodiment of the first aspect of the present invention, the temperature of the first cooling is lower than the temperature of the second cooling, and the temperature of the second cooling is lower than the temperature of the third cooling.

[0027] According to the method for preparing a persulfate catalyst in any embodiment of the first aspect of the present invention, the

[0028] First cooling to 130-160℃;

[0029] Cooling to 230℃~260℃ for the second time;

[0030] The third cooling is to 280℃~320℃.

[0031] According to the method for preparing a persulfate catalyst of any embodiment of the first aspect of the present invention, the molar ratio of the bismuth source, the iron source, and the cerium source is (8-9.5):10:(0.5-2) calculated based on the amount of metal.

[0032] According to the method for preparing the persulfate catalyst of any embodiment of the first aspect of the present invention, the doping molar amount of cerium is 3 to 25% based on the total amount of metal bismuth and cerium;

[0033] Preferably, the doping molar amount of cerium is 4-20%.

[0034] According to the method for preparing a persulfate catalyst according to any embodiment of the first aspect of the present invention, in step S1, the solvent is a mixture of alcohol and water;

[0035] The mixing volume ratio of the alcohol and water is (2.5-5):1.

[0036] According to the method for preparing a persulfate catalyst according to any embodiment of the first aspect of the present invention, in step S1, the alcohol includes any one or more of ethylene glycol, n-propanol, and isopropanol.

[0037] According to the method for preparing a persulfate catalyst according to any embodiment of the first aspect of the present invention, the acid in S2 may include, but is not limited to, any one or both of hydrochloric acid and nitric acid.

[0038] In the method for preparing a persulfate catalyst according to any embodiment of the first aspect of the present invention, the bismuth source includes but is not limited to bismuth nitrate.

[0039] According to the method for preparing a persulfate catalyst according to any embodiment of the first aspect of the present invention, the iron source includes but is not limited to any one or more of ferric nitrate and ferric chloride.

[0040] According to the method for preparing a persulfate catalyst according to any embodiment of the first aspect of the present invention, the cerium source includes but is not limited to cerium nitrate.

[0041] According to the method for preparing a persulfate catalyst according to any embodiment of the first aspect of the present invention, in step S3, calculated based on the amount of metal, the concentration of the bismuth source in the solution is 0.1-0.5 mol / L, the concentration of the iron source is 0.1-0.5 mol / L, and the concentration of the cerium source is 0.008-0.08 mol / L.

[0042] A second aspect of the present invention provides a persulfate catalyst, which is prepared according to the method for preparing the persulfate catalyst according to any embodiment of the first aspect of the present invention.

[0043] A third aspect of the present invention provides an application of a persulfate catalyst for catalyzing persulfate to degrade the antibiotic.

[0044] According to the use of the persulfate catalyst of any embodiment of the third aspect of the present invention, the antibiotic includes sulfamethoxazole. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 BiFeO3 prepared in Comparative Example 1, Bi prepared in Example 1 0.95 Ce0.05 FeO3, Bi prepared in Example 3 0.8 Ce 0.2 SEM imaging of FeO3;

[0046] Figure 2 BiFeO3 prepared in Comparative Example 1, Bi prepared in Example 1 0.95 Ce 0.05 FeO3, Bi prepared in Example 3 0.8 Ce 0.2 XRD pattern of FeO3;

[0047] Figure 3 Bi prepared in Example 1 0.95 Ce 0.05 Elemental distribution diagram of FeO3;

[0048] Figure 4 This is a diagram showing the effect of using a catalyst to degrade sulfamethoxazole in water in an embodiment;

[0049] Figure 5 This is a diagram showing the degradation effect of the prepared catalyst on sulfamethoxazole in water;

[0050] Figure 6 This is the cyclic degradation curve of sulfamethoxazole in water of the prepared catalyst;

[0051] Figure 7 These are the DFT graphs of BFO-5%-D2 prepared in Comparative Example 2 and BFO-5% prepared in Example 1.

[0052] Beneficial effects

[0053] (1) The preparation method of the persulfate catalyst provided by the present invention can enrich the pore structure of the obtained catalyst through multiple high-temperature calcination and cooling treatments; at the same time, the temperature of the latter calcination is higher than the temperature of the previous calcination, which can improve the stability of the catalyst.

[0054] (2) In the preparation method of the persulfate catalyst provided by the present invention, the temperature of the latter cooling is higher than the temperature of the previous cooling, which is beneficial for maintaining the fine pores therein.

[0055] (3) In the preparation method of the persulfate catalyst provided by the present invention, the cerium doping amount is 3% to 20%, preferably not more than 15%. At the same time, the cerium doping amount is not less than 5%, which can ensure the doping effect while not changing the structure of the perovskite oxide. DETAILED DESCRIPTION

[0056] The present disclosure may be more readily understood by reference to the following description in conjunction with the accompanying drawings and examples, all of which constitute a part of this disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions, or parameters described and / or illustrated herein. Further, the terms used herein are for the purpose of describing specific embodiments by way of example only and are not intended to be limiting unless otherwise indicated.

[0057] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. It should be understood that the scope of protection of the present invention is not limited to the specific specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific specific embodiments and are not intended to limit the scope of protection of the present invention. In the following specific embodiments, if the experimental methods of specific conditions are not specified, they are generally in accordance with the conventional methods and conditions of molecular biology within the technology of the art, and such techniques and conditions are fully explained in the literature.

[0058] It should also be understood that, for the sake of clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically not included, each separate embodiment is considered to be combinable with any other embodiment, and the combination is considered to represent another different embodiment. Conversely, for the sake of simplicity, various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or sub-structure itself may also be considered to be an independent embodiment.

[0059] Unless otherwise indicated, it should be understood that each individual element in a list and each combination of individual elements in that list will be interpreted as a different embodiment. For example, a list of embodiments expressed as "A, B, or C" should be interpreted to include embodiments "A," "B," "C," "A or B," "A or C," "B or C," or "A, B, or C."

[0060] In this document, the recitation of ranges of values are intended to include all values within the range, and endpoints of the ranges, unless otherwise indicated. For ranges of numerical values, the endpoints are included in the ranges, and the ranges are inclusive of the endpoints, unless the context clearly dictates otherwise. The recitation of a single value of a numerical range is intended to mean that the range includes the single value, unless the context clearly dictates otherwise. The use of "about" in conjunction with a reference to a value is intended to mean that the value is approximate, and that slight variations are acceptable, depending on the context. Thus, a person of ordinary skill in the art would recognize that a degree of variation is acceptable, on a case-by-case basis, depending on the context. In some instances, the number of significant digits used in expressing a specific value can be indicative of the degree of precision intended for that value. In other instances, the degree of precision intended can be indicated by the use of a series of values in combination with the term "about." Further, all ranges disclosed in this disclosure are inclusive of the endpoints, and the disclosure of a range between two values includes every value and sub-range between the two values.

[0061] In this document, references to "a substance" are references to at least one of such substance and equivalents thereof.

[0062] When describing items by using the conjunctive term "and / or," etc., the description shall be understood to include any one of the associated listed items, as well as all combinations of one or more of them.

[0063] Generally, the use of the term "about" indicates an approximation, which can vary depending on the desired properties obtained by the disclosed subject matter, and will be interpreted based on functionality in a context-dependent manner. Thus, a person of ordinary skill in the art will be able to interpret a degree of variation on a case-by-case basis. In some instances, the number of significant digits used in expressing a specific value can be indicative of the degree of precision intended for that value. In other instances, the degree of precision intended can be indicated by the use of a series of values in combination with the term "about." Further, all ranges disclosed in this disclosure are inclusive of the endpoints, and the disclosure of a range between two values includes every value and sub-range between the two values.

[0064] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs; and the terms and / or combinations of terms used herein are intended to include all equivalents thereof.

[0065] The present application will be described in detail below through specific examples, so that the technical solutions of the present application are easier to understand and master. However, the present application is not limited to the examples, and the described examples are only a part of the examples, but not all the examples. Therefore, they do not limit the present application in any way, and any non-essential improvements and adjustments made by those skilled in the art based on the content of the present application shall fall within the scope of protection of the present application. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor shall fall within the scope of protection of the present application. In the following examples, the experimental methods are described, and if not specifically stated, they are all conventional methods; the reagents and materials are commercially available, unless otherwise specified. Specific embodiments

[0067] Example 1

[0068] S1, dissolve 9.5 mmol of Bi(NO3)3·5H2O and 10 mmol of Fe(NO3)3·9H2O in a mixture of 30 mL of ethylene glycol and 10 mL of deionized water, stir for 5 min, and then ultrasonic for 5 min to make the solution uniform;

[0069] S2, add 0.5 mmol of Ce(NO3)4 and 25 mmol of nitric acid to the solution, stir for 5 min, and then ultrasonic for 5 min to make it dissolve and mix evenly;

[0070] S3, place the solution in a water bath at 65℃ for 2h, and then continue to place the mixed solution in a water bath at 125℃ for 4h, wash the obtained dark brown gel with deionized water and ethanol, centrifuge, and then dry in an oven at 60℃ for 4h; grind the dried solid into powder.

[0071] S4, place the powder in a crucible and calcine in a muffle furnace to obtain a catalyst, denoted as Bi 0.95 Ce 0.05 FeO3(simplified as BFO-5%); the calcination process is as follows:

[0072] heat to 240℃, and perform the first calcination at 240℃ for 40 min; wherein the heating rate is 6℃ / min;

[0073] after the first calcination is completed, cool to 150℃, and then immediately heat to 300℃ for the second calcination, with a calcination time of 50 min; wherein the heating rate from 150℃ to 240℃ is 6℃ / min, and the heating rate from 240℃ to 300℃ is 6℃ / min;

[0074] After the second calcination, the mixture was cooled to 240°C and then immediately heated to 400°C for the third calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0075] After the third calcination, the mixture was cooled to 300°C and then immediately heated to 500°C for the fourth calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0076] The persulfate catalyst prepared in this example is Bi 0.95 Ce 0.05 FeO3,

[0077] Figure 1 (B) is the product Bi 0.95 Ce 0.05 The SEM image of FeO3 shows that Bi 0.95 Ce 0.05 FeO3 doping was successful, and there were regular octahedrons on the surface.

[0078] Figure 3 Product Bi 0.95 Ce 0.05 Element distribution diagram of FeO3. It can be seen from the figure that the elements Bi, Ce, Fe and O are evenly distributed, which is consistent with the SEM results.

[0079] Example 2

[0080] S1. Dissolve 9 mmol Bi(NO3)3·5H2O and 10 mmol Fe(NO3)3·9H2O in a mixture of 30 mL ethylene glycol and 10 mL deionized water, stir for 5 min, and then sonicate for 5 min to mix the solution evenly.

[0081] S2. Add 1 mmol of Ce(NO3)4 to the solution, add 26 mmol of nitric acid, stir for 5 minutes, and then ultrasonicate for 5 minutes to dissolve and mix;

[0082] S3. Place the solution in a water bath at 65°C for 2 hours, then continue to place the mixed solution in a water bath at 125°C for 4 hours, wash the resulting dark brown gel with deionized water and ethanol, centrifuge, and then dry in an oven at 60°C for 4 hours; grind the dried solid into powder.

[0083] S4. Put the powder into a crucible and place it in a muffle furnace for calcination to obtain a catalyst, which is recorded as Bi 0.9 Ce 0.1 FeO3 (abbreviated as BFO-10%); the calcination treatment is specifically as follows:

[0084] The temperature was raised to 240°C, and the first calcination was carried out at 240°C for 40 minutes at a heating rate of 6°C / min.

[0085] After the first calcination, the mixture was cooled to 150°C and then immediately heated to 300°C for the second calcination. The calcination time was 50 min. The heating rate from 150°C to 240°C was 6°C / min, and the heating rate from 240°C to 300°C was 4°C / min.

[0086] After the second calcination, the mixture was cooled to 240°C and then immediately heated to 400°C for the third calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0087] After the third calcination, the mixture was cooled to 300°C and then immediately heated to 500°C for the fourth calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0088] The persulfate catalyst prepared in this example is Bi 0.9 Ce 0.1 FeO3.

[0089] Example 3

[0090] S1. Dissolve 8 mmol Bi(NO3)3·5H2O and 10 mmol Fe(NO3)3·9H2O in a mixture of 30 mL ethylene glycol and 10 mL deionized water, stir for 5 min, and then sonicate for 5 min to mix the solution evenly.

[0091] S2, add 2 mmol of Ce(NO3)4 to the solution, add 27 mmol of nitric acid, stir for 5 minutes, and then ultrasonicate for 5 minutes to dissolve and mix;

[0092] S3. Place the solution in a water bath at 65°C for 2 hours, then continue to place the mixed solution in a water bath at 125°C for 4 hours, wash the resulting dark brown gel with deionized water and ethanol, centrifuge, and then dry in an oven at 60°C for 4 hours; grind the dried solid into powder.

[0093] S4. Put the powder into a crucible and place it in a muffle furnace for calcination to obtain a catalyst, which is recorded as Bi 0.8 Ce 0.2 FeO3 (abbreviated as BFO-20%); the calcination treatment is specifically as follows:

[0094] The temperature was raised to 240°C, and the first calcination was carried out at 240°C for 40 minutes at a heating rate of 6°C / min.

[0095] After the first calcination, the mixture was cooled to 150°C and then immediately heated to 300°C for a second calcination. The calcination time was 50 min. The heating rate from 150°C to 240°C was 6°C / min, and the heating rate from 240°C to 300°C was 4°C / min.

[0096] After the second calcination, the mixture was cooled to 240°C and then immediately heated to 400°C for the third calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0097] After the third calcination, the mixture was cooled to 300°C and then immediately heated to 500°C for the fourth calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0098] The persulfate catalyst prepared in this example is Bi 0.8 Ce 0.2 FeO3, Figure 1 (C) is the product Bi 0.8 Ce 0.2 SEM image of FeO3.

[0099] Comparative Example 1

[0100] This comparative example is basically the same as Example 1, except that no cerium source or nitric acid is added; specifically, it includes:

[0101] S1. Dissolve 10 mmol Bi(NO3)3·5H2O and 10 mmol Fe(NO3)3·9H2O in a mixture of 30 mL ethylene glycol and 10 mL deionized water, stir for 5 min, and then sonicate for 5 min to mix the solution evenly.

[0102] S2. Place the solution in a water bath at 65°C for 2 hours, then continue to place the mixed solution in a water bath at 125°C for 4 hours, wash the resulting dark brown gel with deionized water and ethanol, centrifuge, and then dry in an oven at 60°C for 4 hours; grind the dried solid into powder.

[0103] S3. The powder is placed in a crucible and placed in a muffle furnace for calcination to obtain a catalyst, which is recorded as BiFeO3 (abbreviated as BFO); the calcination process is specifically as follows:

[0104] The temperature was raised to 240°C, and the first calcination was carried out at 240°C for 40 minutes at a heating rate of 6°C / min.

[0105] After the first calcination, the mixture was cooled to 150°C and then immediately heated to 300°C for a second calcination. The calcination time was 50 min. The heating rate from 150°C to 240°C was 6°C / min, and the heating rate from 240°C to 300°C was 6°C / min.

[0106] After the second calcination, the mixture was cooled to 240°C and then immediately heated to 400°C for the third calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0107] After the third calcination, the mixture was cooled to 300°C and then immediately heated to 500°C for the fourth calcination. The calcination time was 60 min, and the heating rate was 4°C / min.

[0108] The persulfate catalyst prepared in this comparative example is BiFeO3, Figure 1 (A) is the SEM image of the product BiFeO3.

[0109] Figure 2 BiFeO3 prepared in Comparative Example 1, Bi prepared in Example 1 0.95 Ce 0.05 FeO3, Bi prepared in Example 3 0.8 Ce 0.2 XRD pattern of FeO3; It can be seen from the figure that compared with BiFeO3 prepared in Comparative Example 1, Ce-doped products Bi prepared in Example 1 and Example 3 0.95 Ce 0.05 FeO3、Bi 0.8 Ce 0.2 The diffraction peak at 28.54° of FeO3 becomes stronger, which corresponds to the (111) lattice plane. 0.95 Ce 0.05 FeO3、Bi 0.8 Ce 0.2 Comparison of FeO3 XRD patterns reveals that the introduction of Ce ions does not result in the appearance of impurity phases in the sample. The XRD diffraction pattern of bismuth ferrite after Ce ion doping is consistent with that before doping, indicating that Ce ions partially replace Bi ions but do not alter the crystal structure of barium ferrate. This is attributed to the fact that the radius of element Ce is close to that of Bi, so the tolerance factor does not change significantly after ion replacement. Ion replacement also suppresses the loss of volatile Bi.

[0110] Comparative Example 2

[0111] This comparative example is basically the same as Example 1, except for the calcination process in step S4. The calcination process in step S4 of this comparative example is specifically as follows:

[0112] The temperature was raised to 300° C. for the first calcination, and the calcination time was 90 min. The heating rate below 240° C. was the same as the heating rate from 150° C. to 240° C. in Example 1; the heating rate from 240° C. to 300° C. was the same as the heating rate from 240° C. to 300° C. in Example 1 (specifically, 6° C. / min).

[0113] After the first calcination, the temperature was immediately raised to 500°C for the second calcination, and the calcination time was 120 min; wherein, the heating rate was the same as the heating rate from 300°C to 500°C in Example 1 (specifically 4°C / min).

[0114] The obtained catalyst was recorded as BFO-5%-D2.

[0115] Comparative Example 3

[0116] This comparative example is basically the same as Example 1, except for the calcination process in step S4. The calcination process in step S4 of this comparative example is specifically as follows:

[0117] The temperature was raised to 240° C. for the first calcination, and the calcination time was 40 min; wherein the heating rate was the same as that in Example 1, which was 6° C. / min;

[0118] After the first calcination, the temperature was immediately raised to 300°C for the second calcination, and the calcination time was 50 minutes; wherein, the heating rate was the same as the heating rate from 240°C to 300°C in Example 1, which was 6°C / min;

[0119] After the second calcination, the temperature was immediately raised to 500°C for the third calcination, and the calcination time was 120 min; wherein, the heating rate was the same as the heating rate from 300°C to 500°C in Example 1, which was 4°C / min.

[0120] The obtained catalyst was recorded as BFO-5%-D3.

[0121] Example 4

[0122] This embodiment is basically the same as embodiment 1, the only difference being the calcination process in step S4. The calcination process in step S4 in this embodiment is specifically as follows:

[0123] The temperature was raised to 240° C., and the first calcination was carried out at 240° C. for 40 min. The heating rate was the same as in Example 1, which was 6° C. / min.

[0124] After the first calcination, the temperature was immediately raised to 300°C for the second calcination, and the calcination time was 50 minutes; wherein, the heating rate was the same as the heating rate from 240°C to 300°C in Example 1, which was 6°C / min;

[0125] After the second calcination, the temperature was immediately raised to 400°C for the third calcination, and the calcination time was 60 minutes; wherein, the heating rate was the same as the heating rate from 240°C to 400°C in Example 1, which was 4°C / min;

[0126] After the third calcination, the temperature was immediately raised to 500° C. for the fourth calcination, and the calcination time was 60 min. The heating rate was the same as that from 300° C. to 500° C. in Example 1, which was 4° C. / min.

[0127] The obtained catalyst was recorded as BFO-5%-D4.

[0128] Example 5

[0129] This embodiment is basically the same as embodiment 1, the only difference being the calcination process in step S4. The calcination process in step S4 in this embodiment is specifically as follows:

[0130] The calcination temperature, time and heating rate of the first calcination are the same as those in Example 1;

[0131] After the first calcination, the mixture was cooled to 150°C and then immediately heated to 300°C for the second calcination (the calcination time was 50 min as in Example 1), and the heating rate was 6°C / min as in Example 1;

[0132] After the second calcination, the mixture was cooled to 150°C and then immediately heated to 400°C for the third calcination (the calcination time was 60 min as in Example 1) at a heating rate of 4°C / min as in Example 1.

[0133] After the third calcination, the mixture was cooled to 150° C. and then immediately heated to 500° C. for the fourth calcination (the calcination time was 60 min as in Example 1), and the heating rate was 4° C. / min as in Example 1.

[0134] The obtained catalyst was recorded as BFO-5%-D5.

[0135] Example 6

[0136] This embodiment is basically the same as embodiment 1, the only difference being the calcination process in step S4. The calcination process in step S4 in this embodiment is specifically as follows:

[0137] The temperature was raised to 400°C and the first calcination was carried out at 400°C for 40 minutes at a heating rate of 6°C / min.

[0138] After the first calcination, the mixture was cooled to 150°C and then immediately heated to 400°C for the second calcination (the calcination time was 50 min as in Example 1) at a heating rate of 6°C / min as in Example 1.

[0139] After the second calcination, the mixture was cooled to 240°C and then immediately heated to 500°C for the third calcination (the calcination time was 60 min as in Example 1) at a heating rate of 4°C / min as in Example 1.

[0140] After the third calcination, the mixture was cooled to 300° C. and then immediately heated to 500° C. for the fourth calcination (the calcination time was 60 min as in Example 1), and the heating rate was 4° C. / min as in Example 1.

[0141] The obtained catalyst was recorded as BFO-5%-D6.

[0142] Example 7

[0143] (1) Degradation experiment of the solution to be degraded containing sulfamethoxazole:

[0144] Prepare a solution to be degraded containing sulfamethoxazole, with a total volume of 200 mL and a sulfamethoxazole concentration of 25 mg / L;

[0145] A catalyst (catalyst concentration of 0.3 g / L) and potassium persulfate (potassium persulfate concentration of 0.8 g / L) were added to the solution to be degraded to catalyze the degradation of sulfamethoxazole by persulfate. Figure 4 The catalytic temperature was 25 degrees Celsius and the catalytic time was 35 minutes.

[0146] Alternatively, a catalyst (catalyst concentration of 0.3 g / L) is added to the liquid to be degraded to catalyze the degradation of sulfamethoxazole by persulfate ( Figure 4 The catalytic temperature was 25 degrees Celsius and the time was 35 minutes.

[0147] Alternatively, potassium persulfate (potassium persulfate concentration is 0.8 g / L) is added to the solution to be degraded to catalyze the degradation of sulfamethoxazole by persulfate ( Figure 4 The catalytic temperature was 25 degrees Celsius and the time was 35 minutes.

[0148] (2) Determination of the concentration of sulfamethoxazole in the degradation solution:

[0149] The concentration of sulfamethoxazole was determined using an Agilent 1260 HPLC system equipped with a ZORBAX Eclipse XDB-C18 column (4.6 mm × 150 mm × 5 μm). The mobile phase was A (acetic acid water) and B (acetonitrile) at a ratio of 30:70, with a flow rate of 0.9 mL / min. -1, detection wavelength 270nm, injection volume 10μL, column temperature 30℃. Every 5 minutes, 2mL of sample was taken with a syringe and filtered through a 0.45μm pore size filter into a liquid phase vial; all samples were measured by liquid chromatography at a wavelength of 270nm.

[0150] Depend on Figure 4 It can be seen that the bismuth ferrite catalysts prepared at different cerium doping ratios (BFO / PMS, BFO-5% / PMS, BFO-10% / PMS and BFO-20% / PMS) all have certain catalytic properties, among which BFO-5% shows the best catalytic effect and can completely degrade sulfamethoxazole within 35 minutes.

[0151] When PMS was added alone, sulfamethoxazole was hardly oxidized and sulfamethoxazole itself was relatively stable.

[0152] When bismuth ferrite (BFO, BFO-5%, BFO-10% and BFO-20%) was added alone, the removal rate of sulfamethoxazole was less than 20% at most due to the limited adsorption effect;

[0153] Furthermore, compared with the addition of PMS or bismuth ferrite (BFO, BFO-5%, BFO-10% and BFO-20%) materials alone, the degradation rate of sulfamethoxazole was greatly improved when the bismuth ferrite catalyst and persulfate were used in combination (BFO / PMS, BFO-5% / PMS, BFO-10% / PMS and BFO-20% / PMS), indicating that the cerium-doped bismuth ferrite catalyst can be used as a catalyst to effectively activate persulfate, thereby achieving effective degradation of sulfamethoxazole wastewater.

[0154] Depend on Figure 5 It can be seen that the efficiency of the non-cerium-doped bismuth ferrite catalyst BiFeO3 (abbreviated as BFO) in Comparative Example 1 decreased significantly after four cycles of use (the removal rate dropped to 64.5%). However, the removal rates of the other cerium-doped bismuth ferrite catalysts were higher than those of the non-cerium-doped bismuth ferrite catalyst BFO after four cycles of use.

[0155] In addition, the product BFO-5%-D2 in Comparative Example 2 was obtained after two calcinations, and the product BFO-5%-D3 in Comparative Example 3 was obtained after three calcinations. Figure 5 It can be seen that after four cycles of use, the removal rates of sulfamethoxazole in BFO-5%-D2 and BFO-5%-D3 were only 66.2% and 69.7% respectively. 0.95 Ce 0.05FeO3 (BFO-5%), BFO-5%-D4 of Example 4, BFO-5%-D5 of Example 5, and BFO-5%-D6 of Example 6 are more stable in efficiency (removal rate is stable at more than 80%) when reused. Figure 7 analyze, Figure 7 (A) is the DFT diagram of the product BFO-5%-D2 obtained by two calcination treatments in Comparative Example 2; Figure 7 (B) DFT diagram of BFO-5% prepared in Example 1; As can be seen from the figure, compared with Figure 7 (A), Figure 7 The pores in (B) change from peaks distributed around 3 nm to multimodal pores, indicating that multiple high-temperature calcinations and cooling treatments enrich the pore structure of the resulting catalyst and increase its specific surface area, indicating that multiple annealing processes are beneficial for enhancing the catalyst's stability and anti-interference properties. The cerium-doped catalyst employed in the present invention can catalyze the degradation of sulfamethoxazole in water at room temperature and pressure with persulfate. The catalyst exhibits excellent stability, exhibits substantially no metal leaching during use, and can be repeatedly used to degrade sulfamethoxazole wastewater.

[0156] It is worth mentioning that the catalytic effect of BFO-5% prepared in Example 1 can still reach 88% when it is used to treat sulfamethoxazole wastewater after four cycles, maintaining a high level, and no metal ion leaching is detected in the solution after the reaction.

[0157] Example 8

[0158] The BiFeO3 (BFO in the figure) prepared in Comparative Example 1 and the BiFeO3 prepared in Example 1 0.95 Ce 0.05 FeO3 (BFO-5% in the figure) was used as a catalyst to repeatedly catalyze potassium persulfate to degrade sulfamethoxazole wastewater;

[0159] The degradation treatment is the same as that of "(1) Degradation experiment of a solution to be degraded containing sulfamethoxazole" in Example 7;

[0160] The concentration of sulfamethoxazole in the solution to be degraded is determined in the same manner as in "(2) Determination of the concentration of sulfamethoxazole in the solution to be degraded" in Example 7;

[0161] After the degradation reaction was completed, the catalyst in the reaction system was recovered by filtration (a sand core filter funnel combined with a 0.45 μm filter membrane). It was washed three times with ethanol and three times with deionized water to remove contaminants remaining on the catalyst surface. The catalyst was then dried in an oven (60°C) to obtain a regenerated catalyst. The degradation and recovery steps were repeated four times, and the catalyst was used to treat sulfamethoxazole wastewater.

[0162] Depend on Figure 6 It can be seen that the cerium-doped bismuth ferrite catalyst BFO-5% can still effectively remove sulfamethoxazole wastewater after four cycles of use, while the efficiency of the undoped bismuth ferrite catalyst BFO decreases significantly after 5 repeated uses (the removal rate drops to 64.5%).

Claims

1. A method for preparing a persulfate catalyst, characterized in that: Including steps: S1. preparing a solution containing a bismuth source and an iron source; S2, adding a cerium source and nitric acid to the solution; S3, treating the solution at 60°C to 75°C for 1.5 hours to 2.5 hours; then treating the solution at 120°C to 130°C for 3 hours to 7 hours to form a gel, and drying and grinding the solution to obtain a solid powder; S4, calcining the solid powder; Calculated based on the amount of metal, the molar ratio of the bismuth source, iron source, and cerium source is (8-9.5): 10：（0.5~2）； The calcination process includes: a first calcination, a first cooling, a second calcination after heating, a second cooling, a third calcination after heating, a third cooling, and a fourth calcination after heating; Wherein, the temperature of any of the cooling is 100~350℃; The first calcination: temperature is 230℃~260℃; time is 20min~60min; Second calcination: temperature is 280℃~320℃; time is 20min~60min; The third calcination: temperature is 380℃~420℃; time is 30min~70min; The fourth calcination: temperature is 480℃~530℃; time is 30min~70min.

2. The method for preparing a persulfate catalyst according to claim 1, wherein The temperature of the first cooling is lower than that of the second cooling, and the temperature of the second cooling is lower than that of the third cooling.

3. The preparation method of persulfate catalyst according to claim 2, wherein described First cooling to 130~160℃; Cooling to 230℃~260℃ for the second time; The third cooling is to 280℃~320℃.

4. The method for preparing a persulfate catalyst according to any one of claims 1 to 3, wherein The doping molar amount of cerium is 3-25% based on the total molar amount of metal bismuth and cerium.

5. A persulfate catalyst, characterized in that The persulfate catalyst is prepared according to any one of claims 1 to 4.

6. Use of the persulfate catalyst according to claim 5, characterized in that: It is used to catalyze persulfate to degrade the antibiotic.

7. The use of the persulfate catalyst according to claim 6, characterized in that The antibiotics include sulfamethoxazole.

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