BiOBr / magnetic zeolite composite photocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a BiOBr / magnetic zeolite composite photocatalyst and a preparation method and application thereof, belongs to the technical field of photocatalysts, the composite photocatalyst is composed of flaky BiOBr and magnetic zeolite particles, the mass fraction of the magnetic zeolite particles is 10%, the specific preparation method of the BiOBr / magnetic zeolite composite photocatalyst and the application of the BiOBr / magnetic zeolite composite photocatalyst in degradation of butyl xanthate are provided. Fe3O4 is loaded on the surface of zeolite by a coprecipitation method to obtain magnetic zeolite (MZ) particles, and then bismuth oxybromide and the magnetic zeolite are compounded by a solvothermal method, so that the performance of the obtained composite photocatalyst is rapidly improved, the composite photocatalyst has the characteristics of high photocatalytic activity, good stability and convenience in recycling, and in the degradation process of butyl xanthate, the photocatalytic activity of the composite photocatalyst is greatly improved. And repeated use can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysts, and in particular to a BiOBr / magnetic zeolite composite photocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of industry, the scale of mining has gradually expanded, and the usage amount of flotation agents has increased. In mining areas, toxic chemical residues in flotation wastewater have led to the deterioration of the ecological environment. Xanthate is the most commonly used and most effective collector for sulfide ores. It can cause serious harm to animals, humans, and natural ecosystems. Therefore, the treatment method of xanthate is of great significance for environmental protection in mining areas. Currently, the main methods for treating xanthate in flotation wastewater include coagulation sedimentation method, adsorption method, advanced oxidation method, and biodegradation method. However, most of these conventional methods have problems such as high cost, low efficiency, and varying degrees of secondary pollution.

[0003] Among them, the photocatalysis technology in the advanced oxidation method is considered to be one of the cleanest and most effective treatment means, and has been proven to be an effective method for degrading xanthate wastewater. The principle is that when the light energy absorbed by the semiconductor catalyst ≥ its band gap energy, the electrons (e - ) on the valence band of the catalyst are excited and transition to the conduction band, generating extremely oxidizing electron holes h+ on the valence band. The photo-generated electron-hole pairs (e - -h + ) can react with O 2 , H 2 O to generate extremely oxidizing ·O 2- , ·OH, and the active substances undergo photocatalytic oxidation-reduction reactions to mineralize xanthate into simple non-toxic small molecules.

[0004] In recent years, due to the advantages of BiOBr such as low price, non-toxicity, and excellent optical activity, it has received extensive attention in the research and development field of visible light-responsive photocatalysts. However, the serious agglomeration phenomenon of single BiOBr reduces the utilization rate of the photocatalyst and the pollutant adsorption and light capture capabilities, and further optimization is required to improve its photocatalytic activity. Loading BiOBr on the surface of the carrier zeolite with good economy, excellent adsorption performance, and large specific surface area can effectively improve the adsorption and photocatalytic performance of the composite material. On the other hand, it is difficult to separate and recycle the solid and liquid after the photocatalytic material is used. The magnetic composite photocatalyst obtained by compounding the photocatalyst with the magnetic material Fe 3 O 4 can achieve rapid solid-liquid separation under the action of an external magnetic field, reduce secondary pollution, and improve the recycling ability.

[0005] Based on this, a BiOBr / magnetic zeolite composite photocatalyst, a preparation method thereof, and an application thereof are proposed. Summary of the Invention

[0006] The object of the present invention is to provide a BiOBr / magnetic zeolite composite photocatalyst, its preparation method and application to solve the problems in the background art.

[0007] To achieve the above object, the present invention provides a BiOBr / magnetic zeolite composite photocatalyst, which is composed of flaky BiOBr and magnetic zeolite particles, and the mass fraction of the magnetic zeolite particles is 10%.

[0008] The present invention also provides a preparation method of a BiOBr / magnetic zeolite composite photocatalyst, including the following steps:

[0009] S1. Put ferric chloride and ferrous sulfate heptahydrate into a zeolite solution, fully dissolve them, and then dropwise add ammonia water to adjust the pH to 10 - 11;

[0010] S2. After continuous stirring, separate with an external magnet to obtain solid particles, wash and dry them to obtain magnetic zeolite nanoparticles;

[0011] S3. Dissolve bismuth nitrate pentahydrate in ethylene glycol, add magnetic zeolite nanoparticles under continuous stirring conditions, and then dropwise add a potassium bromide solution to obtain a suspension precursor;

[0012] S4. Transfer the obtained precursor to a 100 ml polytetrafluoroethylene autoclave for storage, naturally cool to room temperature after solvothermal treatment, separate with an external magnetic field, wash and dry to obtain the BiOBr / magnetic zeolite composite photocatalyst.

[0013] Preferably, in S1, the molar ratio of ferric chloride to ferrous sulfate heptahydrate is 2:1, the content of the zeolite solution is 100 - 120 ml, and the molar concentration of ammonia water is 3 - 4 M.

[0014] Preferably, in S2, the stirring time is 1 - 2 h and the temperature is 50 - 60 °C.

[0015] Preferably, in S3, the dosage of bismuth nitrate pentahydrate is 3 - 4 mmol, the dosage of ethylene glycol is 20 - 40 ml, the addition amount of magnetic zeolite nanoparticles is 0.12 g, 0.48 g or 0.96 g, the potassium bromide solution is 3 - 4 mmol potassium bromide dissolved in 10 - 20 ml of water, and continue to stir for 20 - 30 min after dropping the potassium bromide solution.

[0016] Preferably, in S4, the storage temperature is 160 - 180 °C and the storage time is 10 - 12 h.

[0017] Preferably, the cleaning methods in both S2 and S4 are to rinse 2 - 3 times with distilled water and absolute ethanol respectively, the drying time is 6 - 8 h, and the drying temperature is 60 - 80 °C.

[0018] The present invention also provides an application of the BiOBr / magnetic zeolite composite photocatalyst, which is applied to the photocatalytic degradation of xanthate wastewater.

[0019] Preferably, the BiOBr / magnetic zeolite composite photocatalytic material is used for the photocatalytic degradation experiment of butyl xanthate. The specific process is as follows:

[0020] Take a butyl xanthate solution, add the composite photocatalyst, stir and adsorb in the dark until the adsorption-desorption equilibrium is reached, and then carry out illumination. The light source is a 350W xenon lamp. During the magnetic stirring process, the reaction solution is cooled with circulating water. Take out 4 mL of the suspension every 20 minutes, and then filter to remove the catalyst; use a HACH DR 6000 spectrophotometer to measure the absorbance of the butyl xanthate solution at a wavelength of 301 nm, and then calculate the degradation efficiency of butyl xanthate;

[0021] The degradation efficiency (D) of butyl xanthate can be calculated according to the Lambert-Beer law. The formula is as follows:

[0022]

[0023] Among them, A 0 and A t respectively represent the initial absorbance and the absorbance at time t of the butyl xanthate solution.

[0024] Therefore, for the BiOBr / magnetic zeolite composite photocatalyst, its preparation method and application of the present invention, Fe is loaded onto the zeolite surface by the co-precipitation method 3 O 4 to obtain magnetic zeolite (MZ) particles, and then bismuth oxybromide is combined with magnetic zeolite by the solvothermal method, so that the performance of the obtained composite photocatalyst is rapidly improved, and it has the characteristics of high photocatalytic activity, good stability and convenient recycling, and can be reused during the degradation process of butyl xanthate.

[0025] In the experiment of butyl xanthate degradation, h + and ·OH are the main active species for MZB-10 to degrade butyl xanthate. Both h + and ·OH are active species that cause the photocatalytic degradation of butyl xanthate. In the MZB composite photocatalyst, the hole ·OH plays a major role, and h + plays a minor role.

[0026] The technical solution of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0027] Figure 1 It is the XRD pattern of the products of Examples 1-3 and Comparative Examples 1 and 2 of the present invention;

[0028] Figure 2 This is the overall scanning spectrogram of the product of Example 1 of the present invention. Among them, a is the overall scanning spectrum, b is Bi 4f, c is Br 3d, d is O1s, e is Fe 2P, and f is Si2p;

[0029] Figure 3 This is the photo - electric property detection diagram of the products of Examples 1 - 3 and Comparative Examples 1 and 2 of the present invention;

[0030] Figure 4 This is the N 2 adsorption - desorption isotherm curve graph of the products of Example 1 and Comparative Example 1 of the present invention, where a is Comparative Example 1 and b is Example 1;

[0031] Figure 5 This is the photocatalytic degradation performance effect diagram of the butyl xanthate degradation experiments carried out on the products of Examples 1 - 3 and Comparative Examples 1 and 2 of the present invention respectively;

[0032] Figure 6 This is the hysteresis curve graph of the products of Examples 1 - 3 and Comparative Example 1 of the present invention;

[0033] Figure 7 This is the cyclic detection graph of the butyl xanthate degradation experiment carried out on the product of Example 1 of the present invention. Detailed implementation manners

[0034] The technical solutions of the present invention will be further described below through the accompanying drawings and examples.

[0035] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0036] Example 1

[0037] Prepare the MZB - 10 composite material, and the steps are as follows:

[0038] S1. Place 0.48 g of ferric chloride and 1.67 g of ferrous sulfate heptahydrate in a 100 ml, 7.5 mg·L -1 zeolite solution. After fully dissolving, add dropwise 20 ml of 3 M ammonia water solution to make the pH of the final mixture 11 under vigorous stirring;

[0039] S2. Keep the mixture stirring continuously at 60 °C for 2 h, separate it with an external magnet to obtain solid particles, wash them 3 times with distilled water and anhydrous ethanol respectively, and then dry them at 60 °C for 8 h to obtain magnetic zeolite nanoparticles;

[0040] S3. Dissolve 4 mmol (1.94 g) of bismuth nitrate pentahydrate in 40 ml of ethylene glycol, sonicate for 5 min, and then add 0.12 g of magnetic zeolite nanoparticles under vigorous stirring;

[0041] Subsequently, add dropwise 4 mmol (0.476 g) of potassium bromide dissolved in 20 ml of water to the above mixture, and then stir vigorously for 30 min to form a suspended precursor;

[0042] S4. Transfer the obtained precursor to a 100 ml polytetrafluoroethylene autoclave for storage, and store it at 180 °C for 12 h. After solvothermal treatment, naturally cool the synthesized photocatalyst to room temperature, separate it with an external magnetic field, then rinse it 3 times with distilled water and absolute ethanol, and dry it at 60 °C for 8 h to obtain the MZB-10 composite material.

[0043] Example 2

[0044] Prepare the MZB-40 composite material, and the steps are as follows:

[0045] S1. Place 0.48 g of ferric chloride and 1.67 g of ferrous sulfate heptahydrate in 100 ml of a 7.5 mg·L -1 zeolite solution. After fully dissolving, add dropwise 20 ml of 3 M ammonia water solution to make the pH of the final mixture 11 under vigorous stirring;

[0046] S2. Keep the mixture stirring continuously at 60 °C for 2 h, separate it with an external magnet to obtain solid particles, rinse them 3 times with distilled water and absolute ethanol respectively, and then dry them at 60 °C for 8 h to obtain magnetic zeolite nanoparticles;

[0047] S3. Dissolve 4 mmol (1.94 g) of bismuth nitrate pentahydrate in 40 ml of ethylene glycol, sonicate for 5 min, and then add 0.48 g of magnetic zeolite nanoparticles under vigorous stirring;

[0048] Subsequently, add dropwise 4 mmol (0.476 g) of potassium bromide dissolved in 20 ml of water to the above mixture, and then stir vigorously for 30 min to form a suspended precursor;

[0049] S4. Transfer the obtained precursor to a 100 ml polytetrafluoroethylene autoclave for storage, and store it at 180 °C for 12 h. After solvothermal treatment, naturally cool the synthesized photocatalyst to room temperature, separate it with an external magnetic field, then rinse it 3 times with distilled water and absolute ethanol, and dry it at 60 °C for 8 h to obtain the MZB-40 composite material.

[0050] Example 3

[0051] Prepare the MZB-80 composite material, and the steps are as follows:

[0052] S1. Place 0.48 g of ferric chloride and 1.67 g of ferrous sulfate heptahydrate into 100 ml of 7.5 mg·L -1 zeolite solution. After complete dissolution, add dropwise 20 ml of 3 M ammonia solution to make the pH of the final mixture 11 under vigorous stirring;

[0053] S2. Keep the mixture stirring continuously at 60 °C for 2 h, separate it with an external magnet to obtain solid particles, rinse them 3 times with distilled water and anhydrous ethanol respectively, and then dry them at 60 °C for 8 h to obtain magnetic zeolite nanoparticles;

[0054] S3. Dissolve 4 mmol (1.94 g) of bismuth nitrate pentahydrate in 40 ml of ethylene glycol, sonicate for 5 min, and then add 0.96 g of magnetic zeolite nanoparticles under vigorous stirring conditions;

[0055] Subsequently, add dropwise 4 mmol (0.476 g) of potassium bromide dissolved in 20 ml of water into the above mixture, and then stir vigorously for 30 min to form a suspended precursor;

[0056] S4. Transfer the obtained precursor to a 100 ml polytetrafluoroethylene autoclave for preservation, and keep it at 180 °C for 12 h. After solvothermal treatment, naturally cool the synthesized photocatalyst to room temperature, separate it with an external magnetic field, then rinse it 3 times with distilled water and anhydrous ethanol respectively, and dry it at 60 °C for 8 h to obtain the MZB-80 composite material.

[0057] Comparative Example 1

[0058] Prepare BiOBr, the steps are as follows:

[0059] Dissolve 4 mmol (1.94 g) of bismuth nitrate pentahydrate in 40 ml of ethylene glycol, sonicate for 5 min, add dropwise 4 mmol (0.476 g) of potassium bromide dissolved in 20 ml of water into the above mixture, and then stir vigorously for 30 min to form a suspended precursor; transfer the obtained precursor to a 100 ml polytetrafluoroethylene autoclave for preservation, and keep it at 180 °C for 12 h to obtain BiOBr.

[0060] Comparative Example 2

[0061] Prepare magnetic zeolite, the steps are as follows:

[0062] Place 0.48 g of ferric chloride and 1.67 g of ferrous sulfate heptahydrate into 100 ml of 7.5 mg·L -1 zeolite solution. After complete dissolution, add dropwise 20 ml of 3 M ammonia solution to make the pH of the final mixture 11 under vigorous stirring;

[0063] The mixture was continuously stirred at 60 °C for 2 h, separated by an external magnet to obtain solid particles, rinsed 3 times with distilled water and absolute ethanol respectively, and then dried at 60 °C for 8 h to obtain magnetic zeolite nanoparticles.

[0064] The photocatalysts prepared in Examples 1-3 and Comparative Examples 1 and 2 above were detected, and their XRD patterns are as Figure 1 shown. For the BiOBr sample, the main detected peaks can be well indexed to the tetragonal phase structure planes of (001), (002), (101), (102), (110), (112), (200) and (212) (JCPDS No. 09-0393). The 2θ values of 30.10°, 35.42°, 43.05°, 56.94° and 62.52° correspond to the Fe 3 O 4 lattice planes of (220), (311), (400), (511), (440) (JCPDS No. 77-1545). The diffraction peak at 2θ value of 22.49° indicates the presence of the zeolite phase. In the XRD spectrum of MZB-10, the diffraction peaks of BiOBr, Fe 3 O 4 and zeolite can be seen, confirming the successful preparation of the composite material. However, the diffraction peak of MZ is relatively weak. The reason is that in the MZB-10 catalyst, the content of MZ is small, and the diffraction peak of the Fe 3 O 4 monomer itself is also relatively weak.

[0065] For Example 1, the XPS method was used to study the elemental composition and valence state of the surface of the MZB-10 composite material, as Figure 2 shown. Figure 2 In a of, the overall scanning spectrum of the MZB-10 nanocomposite material is described. The O, Br, Bi, Fe and Si elements coexist in the BiOBr-10 nanocomposite material; in Figure 2 In the high-resolution spectrum of Bi 4f in b of, there are two obvious peaks at 159.5 eV and 165.1 eV, which are related to Bi 4f 5 / 2 and Bi 4f 3 / 2 respectively, and both belong to Bi 3+ in BiOBr. In Figure 2 c of, the Br 3d of MZB-10 has two peaks at 68.03 eV and 69.07 eV, which come from Br 3d 3 / 2 and Br 3d 5 / 2， of the Br 3d orbital respectively, revealing the -1 valence of Br in the catalyst. In Figure 2In d of MZB-10, two characteristic peaks of O 1s are shown. The peak at 530.1 eV corresponds to the Bi-O bond in the BiOBr lattice, and the characteristic peak at 531.8 eV corresponds to surface-adsorbed -OH / H 2 O. In Figure 2 e of it, the two peaks at 710.9 eV and 723.8 eV are Fe 2P 3 / 2 and Fe 2P 1 / 2 respectively. In addition, in Figure 2 f of it, the characteristic peak site of Si 2p appears at a binding energy of 102.5 eV, belonging to Si-O-Si. These results further prove the presence of BiOBr, magnetite, and zeolite in the prepared composite material, indicating the successful preparation of the composite material.

[0066] The efficiency of photoinduced charge separation is a key factor affecting photocatalytic activity. An electrochemical workstation CHI760E was used to measure the migration and separation efficiency of the generated e - / h + pairs. Generally speaking, the higher the photocurrent density, the higher the carrier separation efficiency. For Examples 1-3 and Comparative Examples 1 and 2, photoelectric performance detection was carried out. As Figure 3 shown, the photocurrent intensity of BiOBr is weak, indicating the rapid recombination of photoinduced charges, while the photocurrent response of MZB-10 is significantly enhanced. The transient photocurrent of BiOBr is only 0.03 μA·cm -2 , while that of MZB-10 is as high as 0.13 μA·cm -2 , which is 3 times that of BiOBr. The above results show that due to the good conductivity of MZ, the interfacial charge transfer and separation on MZB-10 are fast.

[0067] The N 2 adsorption-desorption isotherm curve was used to study the specific surface area and pore volume of the catalyst. BET analysis was carried out on Examples 1-3 and Comparative Examples 1 and 2. It can be seen from Figure 4 that the N 2 adsorption-desorption isotherms of BiOBr and MZB-10 both belong to Type IV isotherms and both show clear H3-type hysteresis loops, indicating that the samples contain rich mesoporous structures. The BET model was used to calculate the specific surface areas of the BiOBr and MZB-10 composite materials, which are 17.7 m 2 / g and 37.7 m 2 / g. Generally speaking, materials with a larger specific surface area have better photocatalytic activity because there are many active sites distributed on the material surface. The larger the BET, the more active sites can be exposed on the material surface. After introducing MZ into BiOBr, the BET surface area of BiOBr increases significantly, which is beneficial to the adsorption of organic molecules and provides more active sites during the photocatalytic degradation process. Based on the BJH model, the pore volumes of the two samples were calculated. The pore volumes of BiOBr and MZB-10 are 0.04 m 3 / g and 0.09 m 3 / g.

[0068] Application Example

[0069] In the photocatalytic degradation of xanthate wastewater, the specific steps are as follows:

[0070] Using a 350W xenon lamp as the light source, 15 mg of the prepared photocatalyst solid powder was put into a quartz reactor containing 50 mL of 50 mg / L butyl xanthate solution (maintaining room temperature). Butyl xanthate was selected as the target pollutant. Under two conditions of dark state and light irradiation, the photocatalytic activity of the BiOBr / magnetic zeolite photocatalyst was studied. Under the condition of xenon lamp irradiation, 5 mL of the reacted suspension was taken every 20 minutes. After filtration, the absorbance of butyl xanthate at 301 nm was detected by an ultraviolet-visible spectrophotometer to analyze the photocatalytic degradation effect. The test results are shown in Figure 5 .

[0071] Using the above experimental method, the products obtained in Examples 1-3 and Comparative Examples 1 and 2 were used as photocatalyst solid powders for experiments respectively, and the experiment without adding a photocatalyst was used as a blank control experiment. The photocatalytic degradation performance of different photocatalysts on butyl xanthate is as Figure 5 shown. When no photocatalyst was added, butyl xanthate did not degrade, indicating that butyl xanthate is stable under light irradiation conditions. It can be seen from the figure that MZ can basically not degrade butyl xanthate, while BiOBr and MZB can effectively degrade butyl xanthate. Under the stirring condition in the dark state, the photocatalyst shows adsorption characteristics, and the adsorption of butyl xanthate reaches equilibrium within 30 minutes. When the xenon lamp irradiation time is 120 minutes, compared with the photocatalysts with different MZ mass ratios, the photocatalytic degradation performance of MZB-10 is the strongest, and the removal efficiency of butyl xanthate reaches 99.3%.

[0072] The magnetic properties of the photocatalyst were detected. The magnetic properties of the BiOBr and MZB composite materials with different ratios were studied using a vibrating sample magnetometer. The hysteresis curves of MZB and BiOBr with different ratios measured at room temperature are as Figure 6As shown, the saturation magnetization (Ms) values of MZB-10 and BiOBr are 3.62 emu / g and 0 emu / g, respectively. Although the Ms of MZB-10 is much lower than that of MZ, it is still sufficient for magnetic recovery. As Figure 6 shown in the inset of, MZB-10 can be magnetically separated under an applied magnetic field, indicating its good solid-liquid separation and recovery capabilities. The efficient recovery of MZB-10 is beneficial for its reuse, thereby reducing costs and improving the feasibility of practical applications.

[0073] To investigate the recyclability of the photocatalyst, a photocatalytic stability experiment was conducted on MZB-10 with the mass of the photocatalyst and the concentration of butyl xanthate remaining unchanged. In the recycling experiment, the dark reaction adsorption was carried out for 30 min, and after the photocatalytic reaction for 120 min, MZB-10 was filtered, washed, and dried, and then the dark reaction for 30 min and the photocatalytic reaction for 120 min were carried out in turn, and so on, for five cycles. The results are as Figure 7 shown. It can be seen that through 5 repeated catalytic degradation experiments, the photocatalytic degradation efficiency of MZB-10 for butyl xanthate is still as high as 90.5%, which is only 8.8% lower than the photocatalytic degradation efficiency during the first use. It can be seen that the BiOBr / magnetic zeolite composite photocatalyst prepared in the present invention has good catalytic stability and can be reused.

[0074] Therefore, for a BiOBr / magnetic zeolite composite photocatalyst, its preparation method and application in the present invention, Fe is loaded onto the surface of the zeolite by the co-precipitation method 3 O 4 to obtain magnetic zeolite (MZ) particles, and then bismuth oxybromide is combined with the magnetic zeolite by the solvothermal method, so that the performance of the obtained composite photocatalyst is rapidly improved, and it has the characteristics of high photocatalytic activity, good stability, and easy recovery and reuse. Moreover, it can be reused during the degradation process of butyl xanthate.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A BiOBr / magnetic zeolite composite photocatalyst, characterized in that: The invention is composed of flaky BiOBr and magnetic zeolite particles, wherein the mass fraction of the magnetic zeolite particles is 10%.

2. A method for preparing the BiOBr / magnetic zeolite composite photocatalyst as claimed in claim 1, characterized in that: The following steps are involved: S1. Place ferric chloride and ferrous sulfate heptahydrate in a zeolite solution, and after fully dissolving, add ammonia water to adjust the pH to 10-11; S2, after continuous stirring, separation is performed using an external magnet to obtain solid particles, which are then washed and dried to obtain magnetic zeolite nanoparticles; S3, dissolving bismuth nitrate pentahydrate in ethylene glycol, adding magnetic zeolite nanoparticles under continuous stirring, and then dropping potassium bromide solution to obtain a suspended precursor; S4. The obtained precursor was transferred to a 100 ml polytetrafluoroethylene autoclave for storage, naturally cooled to room temperature after solvent thermal treatment, separated by an external magnetic field, and washed and dried to obtain a BiOBr / magnetic zeolite composite photocatalyst.

3. The method for preparing a BiOBr / magnetic zeolite composite photocatalyst according to claim 2, characterized in that: In the S1, the molar ratio of ferric chloride to ferrous sulfate heptahydrate is 2:1, the content of the zeolite solution is 100-120 ml, and the molar concentration of ammonia water is 3-4M.

4. The method for preparing a BiOBr / magnetic zeolite composite photocatalyst according to claim 2, characterized in that: In S2, the stirring time is 1 to 2 hours and the temperature is 50 to 60°C.

5. The method for preparing a BiOBr / magnetic zeolite composite photocatalyst according to claim 2, characterized in that: In S3, the amount of bismuth nitrate pentahydrate is 3-4 mmol, the amount of ethylene glycol is 20-40 ml, the amount of magnetic zeolite nanoparticles added is 0.12 g, 0.48 g or 0.96 g, the potassium bromide solution is 3-4 mmol potassium bromide dissolved in 10-20 ml water, and stirring is continued for 20-30 min after the potassium bromide solution is added dropwise.

6. The method for preparing a BiOBr / magnetic zeolite composite photocatalyst according to claim 2, characterized in that: In S4, the storage temperature is 160-180° C. and the storage time is 10-12 hours.

7. The method for preparing a BiOBr / magnetic zeolite composite photocatalyst according to claim 2, characterized in that: The cleaning methods in S2 and S4 are both to use distilled water and anhydrous ethanol for 2 to 3 times respectively, with a drying time of 6 to 8 hours and a drying temperature of 60 to 80°C.

8. An application of the BiOBr / magnetic zeolite composite photocatalyst as claimed in claim 1, characterized in that: The BiOBr / magnetic zeolite composite photocatalyst was applied to photocatalytic degradation of xanthate wastewater.

9. The use of a BiOBr / magnetic zeolite composite photocatalyst according to claim 8, characterized in that: The BiOBr / magnetic zeolite composite photocatalytic material was used to carry out a photodegradation experiment of butyl xanthate, and the specific process was as follows: A butyl xanthate solution was added with a composite photocatalyst, and stirred and adsorbed in the dark to reach an adsorption-desorption equilibrium. Then, the solution was illuminated with a 350W xenon lamp as the light source. During the magnetic stirring process, the reaction solution was cooled with circulating water. 4 mL of the suspension was taken out every 20 minutes and then filtered to remove the catalyst. The absorbance of the butyl xanthate solution was measured at a wavelength of 301 nm using a HACH DR 6000 spectrophotometer, and the degradation efficiency of the butyl xanthate was calculated.

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