Persulfate catalyst as well as preparation method and application thereof

Abstract

The invention discloses a persulfate catalyst as well as a preparation method and application thereof. The preparation method comprises a calcining treatment step, wherein the calcining treatment comprises the following steps: calcining for the first time, cooling for the first time, calcining for the second time after heating, cooling for the second time, calcining for the third time after heating, cooling for the third time, and calcining for the fourth time after heating; moreover, the temperature of the next calcination is higher than the temperature of the previous calcination. The porous structure of the obtained catalyst can be enriched through multiple times of high-temperature calcination and cooling treatment; meanwhile, the temperature of the next calcination is higher than the temperature of the previous calcination, so that the stability of the catalyst can be improved.

Description

Technical Field

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

[0002] Sulfadimethoxazole (SMX) is a typical synthetic broad-spectrum antibiotic commonly used to treat bacterial infections, especially in aquaculture and animal husbandry. After use, only a small portion of SMX can be metabolized or absorbed by living systems, and most of it enters wastewater treatment plants. Due to the stable chemical properties of SMX, it is difficult to degrade it by traditional activated sludge methods. Therefore, it is necessary 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 produces a large amount of sulfate (·SO4-). Compared with hydroxyl radicals (·OH), sulfate (·SO4-) shows enhanced selectivity, excellent redox potential and longer life, thus promoting the effective degradation of pollutants in water environments. The use of transition metal ion-doped materials to catalyze persulfate is considered to be an effective method for generating free radicals. As a typical perovskite oxide (ABO3) and a good heterogeneous catalyst, BiFeO3 material has good magnetic properties and acid and alkali resistance (refer to non-patent literature 1), and can catalyze persulfate by separating electrons and holes under ultrasonic excitation. Doping is an effective method to modify the structure of existing catalysts, making it widely used in catalytic degradation-related technologies. The properties of perovskite materials can be changed by doping ions to improve the activity of existing catalysts. After ion doping, the catalytic activity of the material will be improved. However, doped materials usually have secondary pollution problems caused by the outflow of metal ions, as well as low efficiency of material reuse (refer to 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 stimulate 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, LWand KE 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 purposes 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 solution adopted by the present invention is 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 1.5h to 2.5h; then treating the solution at 120°C to 130°C for 3h to 7h to form a gel, and drying and grinding to obtain a solid powder;

[0014] S4, calcining the solid powder;

[0015] The calcination treatment 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 treatment 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 cooling 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°C;

[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 a persulfate catalyst of any embodiment of the first aspect of the present invention, the doping molar amount of cerium is 3 to 25% calculated 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, wherein the persulfate catalyst is prepared according to the method for preparing the persulfate catalyst according to any embodiment of the first aspect of the present invention.

[0043] The 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 The BiFeO3 prepared in Comparative Example 1 and the 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 The BiFeO3 prepared in Comparative Example 1 and the 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 The cyclic degradation curve of sulfamethoxazole in water of the prepared catalyst is shown;

[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 without changing the structure of the perovskite oxide. DETAILED DESCRIPTION

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

[0057] It should be noted that the terms used here 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 indicated, they are generally in accordance with the conventional methods and conditions of molecular biology within 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, the 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 substructure 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 the list will be interpreted as a different embodiment. For example, a list of embodiments represented 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 article, the endpoints and any value of the disclosed scope are not limited to the accurate scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered as specifically disclosed in this article. Unless the context clearly indicates otherwise, the singular form "one", "a kind of" and "described" as used herein include singular and plural indicators. The numerical range described by the endpoint is included in all numerical values ​​and fractions within the corresponding range, and the described endpoint, unless the context clearly indicates otherwise.

[0061] In this document, reference to "a substance" is a reference to at least one of that substance and its equivalents.

[0062] When items are described by using the conjunction terms "... and / or...," etc., the description should be understood to include any one of the associated listed items and all combinations of one or more thereof.

[0063] In general, the use of the term "about" indicates an approximate value that may vary depending on the desired properties obtained by the disclosed subject matter, and will be interpreted in a context-dependent manner based on function. Therefore, one of ordinary skill in the art will be able to interpret a certain degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about". In other cases, a gradient in a range of values ​​can be used to determine the range of differences allowed by the term "about". Further, all ranges in this disclosure are inclusive and combinable, and reference to the values ​​stated in the range includes each value within the range.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0065] The present invention is described below by specific embodiments to make the technical solution of the present invention easier to understand and grasp, but the present invention is not limited thereto, and the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Therefore, they do not impose any restrictions on the present invention, and some non-essential improvements and adjustments made by technicians in this field based on the content of the present invention belong to the protection scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should belong to the protection scope of the present invention. The experimental methods described in the following embodiments, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from commercial channels. Specific embodiments

[0067] Example 1

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

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

[0070] 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 obtained 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.

[0071] 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 0.95 Ce 0.05 FeO3 (abbreviated as BFO-5%); the calcination treatment is specifically as follows:

[0072] The temperature was raised to 240°C, and the first calcination was carried out at 240°C for 40 minutes, wherein the heating rate was 6°C / min;

[0073] 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 6°C / 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 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 make the solution uniform;

[0081] S2, add 1 mmol of Ce(NO3)4 to the solution, add 26 mmol of nitric acid, stir for 5 min, and then ultrasonicate for 5 min 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 obtained 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, wherein the heating rate was 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 make the solution uniform;

[0091] S2, add 2 mmol of Ce(NO3)4 to the solution, add 27 mmol of nitric acid, stir for 5 min, and then ultrasonicate for 5 min 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 obtained 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, wherein the heating rate was 6°C / min;

[0095] 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.

[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 and nitric acid are 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 make the solution uniform;

[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 obtained 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, putting the powder into a crucible, placing it in a muffle furnace for calcination to obtain a catalyst, 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, wherein the heating rate was 6°C / min;

[0105] 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 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 The BiFeO3 prepared in Comparative Example 1 and the Bi prepared in Example 1 0.95 Ce 0.05 FeO3, Bi prepared in Example 3 0.8 Ce 0.2 XRD diagram of FeO3; it can be seen from the figure that compared with BiFeO3 prepared in Comparative Example 1, the Ce-doped product 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 The XRD comparison of FeO3 shows that the introduction of Ce ions will not lead to 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 will replace some Bi ions, but will not cause changes in the crystal structure of barium ferrate. The reason for the analysis is that the radius of the element Ce is close to the ionic radius of the element Bi, so the tolerance factor will not change significantly after ion replacement, and ion replacement can also inhibit the loss of the volatile element Bi.

[0110] Comparative Example 2

[0111] This comparative example is basically the same as Example 1, except for the calcination treatment in step S4; the calcination treatment in step S4 in 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 minutes; wherein 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 treatment in step S4; the calcination treatment in step S4 in 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 6° C. / min, the same as that in Example 1;

[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 4°C / min, the same as the heating rate from 300°C to 500°C in Example 1.

[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 performed at 240° C. for 40 min. The heating rate was 6° C. / min as in Example 1.

[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 min; 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 minutes. The heating rate was the same as the heating rate 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), and the heating rate was 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 temperature 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), and the heating rate was 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), and the heating rate was 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 degradable solution containing sulfamethoxazole:

[0144] Prepare a degradation solution containing sulfamethoxazole, with a total volume of 200 mL and a concentration of sulfamethoxazole 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 liquid to be degraded to catalyze the degradation of sulfamethoxazole ( Figure 4 The catalytic temperature was 25 degrees Celsius and the 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 of 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 high performance liquid chromatograph equipped with a chromatographic column model and specification of ZORBAX Eclipse XDB-C18 (4.6 mm × 150 mm × 5 μm). The mobile phase was A (acetic acid water) : B (acetonitrile) = 30:70, and the flow rate was 0.9 mL min -1, detection wavelength 270nm, injection volume 10μL, column temperature 30℃. Take 2mL sample with syringe every 5 minutes, filter into liquid vial with filter membrane with pore size of 0.45μm; all samples are measured by liquid chromatography at 270nm wavelength.

[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 bismuth ferrite catalyst BiFeO3 (abbreviated as BFO) not doped with cerium in Comparative Example 1 decreased significantly after four cycles of use (the removal rate dropped to 64.5%). For the other bismuth ferrite catalysts doped with cerium, the removal rates were higher than those of the bismuth ferrite catalyst BFO not doped with cerium 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 after two calcination treatments in Comparative Example 2; Figure 7 (B) DFT diagram of BFO-5% prepared in Example 1; it can be seen from the figure that compared with Figure 7 (A) Figure 7 The pores in (B) are changed from peaks distributed at about 3 nm to multi-peak pores, from which it can be seen that the pore structure of the obtained catalyst can be enriched and the specific surface area of ​​the obtained catalyst can be increased after multiple high-temperature calcinations and cooling treatments, indicating that multiple annealing is beneficial to enhancing the stability and anti-interference of the catalyst. It can catalyze the degradation of sulfamethoxazole in water by persulfate at normal temperature and pressure. The cerium-doped catalyst used in the present invention has excellent stability, and there is basically no metal leaching during the application process, and can be used for degrading sulfamethoxazole wastewater many times.

[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 at a relatively high level, and no leaching of metal ions 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 (BFO in the figure) prepared in Example 1 0.95 Ce 0.05 FeO3 (BFO-5% in the figure) is 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 is completed, the catalyst in the reaction system is recovered by suction filtration (sand core filter funnel combined with 0.45 μm filter membrane), washed three times with ethanol and deionized water respectively to remove pollutants remaining on the catalyst surface, and then dried in an oven (60° C.) to obtain a regenerated catalyst. The operations in the degradation step and the recovery step are repeated, and the sulfamethoxazole wastewater is repeatedly treated with the catalyst, which is repeated 4 times, and the catalyst is used 5 times in total.

[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 is significantly reduced after 5 repeated uses (the removal rate drops to 64.5%).

Claims

1. A method for preparing a persulfate catalyst, characterized in that: Includes 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 1.5h to 2.5h; then treating the solution at 120°C to 130°C for 3h to 7h to form a gel, and drying and grinding to obtain a solid powder; S4, calcining the solid powder; The calcination treatment includes: a first calcination, a second calcination after heating, a third calcination after heating, and a fourth calcination after heating; Wherein, the temperature of any calcination treatment is 200-500° C., and the calcination time of each treatment is 10-90 minutes.

2. The method for preparing a persulfate catalyst according to claim 1, wherein 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.

3. The method for preparing a persulfate catalyst according to claim 2, wherein Said 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.

4. The method for preparing a persulfate catalyst according to any one of claims 1 to 3, characterized in that: The calcination process further comprises: a first cooling, a second cooling, and a third cooling; That is, the calcination treatment 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 cooling is 100-350°C.

5. The method for preparing a persulfate catalyst according to claim 4, 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.

6. The method for preparing a persulfate catalyst according to claim 5, characterized in that: Said First cooling to 130-160°C; Cooling to 230℃~260℃ for the second time; The third cooling is to 280℃~320℃.

7. The method for preparing a persulfate catalyst according to any one of claims 1 to 3 or 5 to 6, characterized in that: 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)。 8. The method for preparing a persulfate catalyst according to any one of claims 1 to 3 or 5 to 6, characterized in that: Calculated based on the total molar amount of metal bismuth and cerium, the doping molar amount of cerium is 3-25%.

9. A persulfate catalyst, characterized in that: The persulfate catalyst is prepared according to any one of claims 1 to 8.

10. An application of a persulfate catalyst, characterized in that: Used to catalyze persulfate to degrade the antibiotic; and / or, The antibiotics include sulfamethoxazole.

Images