Microcystin-degrading agent in water, and preparation method and application thereof

Abstract

The application discloses a microcystin degradation agent in water, a preparation method and application thereof, and utilizes oxalic acid and siderite to prepare a compound oxalic acid degradation agent, the degradation agent can degrade microcystin and antibiotic pollutant cefazolin sodium in water, and the degradation reaction can be carried out in dark light conditions, meanwhile, the reaction pH has a wide range, and the degradation can be carried out at pH 5-9; the degradation agent can degrade more than 93% of the microcystin within 26 hours, and the degradation rate of the cefazolin sodium can reach more than 93% within 10 hours, which indicates that the degradation agent prepared by compounding oxalic acid on the surface of the siderite can be applied to the degradation and removal of microcystin and organic pollutants such as antibiotics in water without external light, and therefore has wide application value.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a microcystin degrading agent for water, its preparation method, and its application. Background Technology

[0002] Eutrophication of water bodies caused by the disorderly discharge of nitrogen and phosphorus nutrients has long been a research hotspot for aquatic environment and ecology scholars. Surveys indicate that over 60% of lakes in my country are in a state of eutrophication to varying degrees. The resulting algal blooms, particularly cyanobacterial blooms, not only disrupt the ecological balance of the aquatic environment but also seriously threaten human health. Nearly 50% of known cyanobacterial blooms produce toxic compounds, among which microcystins (MCs) are the most widespread, produced in the largest quantities, and are the most harmful, with over 80 isomers identified to date. Microcystin LR (MC_LR) is currently the most prevalent and toxic of these compounds, entering the human body through various routes including skin contact, drinking water, and the food chain. It can damage the liver, lungs, heart, and trachea, leading to hepatitis, liver failure, and liver cancer. There are also reports that MC_LR can enter the human brain, causing neurotoxicity. Given these concerns, the removal of MC_LR from water bodies is urgently needed.

[0003] MC_LR has a stable structure and is difficult to degrade in the natural environment. Conventional water purification processes such as coagulation-sedimentation-filtration-disinfection are not very effective in removing MCs, and may even exacerbate MC_LR pollution in the effluent due to algal cell rupture and oxidation. Therefore, the effective degradation of MCs has become a research hotspot. Current methods for removing MC_LR include physical adsorption, membrane filtration, traditional chemical oxidation degradation, biodegradation, and advanced oxidation methods. However, physical methods primarily transfer pollutants rather than truly removing them; traditional chemical oxidants can only remove a portion of MC_LR and easily generate disinfection byproducts causing secondary pollution; while microbial degradation technology is low-cost and ecologically safe, it has limited effective bacterial strains and currently cannot achieve harmlessness or mineralization of MC_LR through biodegradation. Furthermore, the analysis and identification of degradation products are still incomplete. Advanced oxidation methods, which generate free radicals, can theoretically degrade MC_LR efficiently and safely, but currently suffer from stringent reaction conditions, requiring ultraviolet light, ultrasound, and acidic conditions. Therefore, if an MC_LR degrading agent could be prepared to reduce the requirements for reaction conditions, it would be possible to simply, efficiently, and with low energy consumption degrade MC_LR pollutants in water.

[0004] Natural mineral raw materials and materials are an extremely important class of natural resources, widely used in various sectors of industry, agriculture, and science and technology. Natural minerals have good compatibility with the ecological environment and directly possess the function of pollution prevention and environmental remediation. They can remove various pollutants from the environment through multiple mechanisms such as adsorption, oxidative degradation, and hydrolysis. Because these minerals originate from nature and have advantages such as abundance, low cost, and environmental friendliness, they are considered the most attractive materials for purifying soil, groundwater, sediments, and industrial wastewater. Utilizing them as catalysts for the purification and degradation of pollutants is also an increasingly popular in-situ pollution control technology. Fang et al., 2018, found that under anaerobic conditions, siderite (FeCO3) can purify and degrade pollutants through the adsorption of HCO3- on its surface. Acid catalysis hydrolyzes the core peptide bonds of MC_LR, achieving a degradation rate of 36.7% for 10 mg / L MC_LR under anaerobic conditions at 30 °C for 48 h in the dark. Neyens et al., 2003 discovered that based on Fe... 2+ The reaction with H₂O₂ produces hydroxyl radicals, which steal hydrogen atoms from organic matter (RH) to generate corresponding active organic groups. These active groups and hydroxyl radicals further react with the organic matter to generate various oxidation products, which are ultimately mineralized into carbon dioxide and water, a process known as the Fenton system. Studies have shown that this system can achieve a degradation efficiency of over 90% for both microcystin-LR and microcystin-RR after 30 minutes of reaction. However, conventional natural minerals have low efficiency in decomposing and purifying pollutants, and some minerals themselves can become sources of acidic pollution. To improve the adsorption and catalytic properties of minerals, modification is usually necessary. Currently, the main methods for mineral surface modification include acid modification, alkali modification, thermal modification, and composite with semiconductors. Among these, acid and alkali can alter the functional groups on the mineral surface, thereby improving the adsorption performance and catalytic activity of the mineral, making it a very effective and user-friendly modification method. Rao Wenxiu discovered that acid modification of kaolinite not only increases its specific surface area and surface acidity but also forms a large number of porous structures. Colina reacted uncalcined kaolinite with four inorganic acid solutions (HCl, HNO3, HPO4, and H2SO4) at relatively high temperatures and found that only the H2SO4 solution reacted well with kaolinite, dissolving Al, Fe, and Ti ions in the system, and significantly increasing the specific surface area of ​​kaolinite. However, how to achieve the degradation of pollutants by acid-modified mineral materials under conventional experimental conditions, such as aerobic and dark environments, while ensuring good degradation results, remains an urgent problem to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a microcystin degrading agent for water. It is prepared by soaking natural mineral siderite in an oxalic acid solution to make the siderite surface composite with oxalic acid, thus creating a catalyst capable of degrading organic pollutants. This catalyst can efficiently remove microcystin toxins (MC-LR) and antibiotic pollutants such as cefazolin sodium from water under dark conditions.

[0006] To achieve the above objectives, the present invention provides a microcystin degrading agent for water, which is prepared by compounding oxalic acid on the surface of siderite.

[0007] Preferably, the concentration of oxalic acid is 0.25-2 mol / L.

[0008] This invention also provides a method for preparing a microcystin degrading agent in water, comprising the following steps:

[0009] (1) Siderite is crushed, sieved, settled and vacuum dried to obtain siderite powder;

[0010] (2) Place the siderite powder in an oxalic acid aqueous solution and soak it at 60°C for 2-3 hours. Filter and retain the precipitate.

[0011] (3) Wash the precipitate with water several times until the washing solution is neutral to obtain a mineral sample;

[0012] (4) The sample obtained in step (3) is filtered and vacuum dried to obtain a microcystin degrading agent in water.

[0013] Preferably, the sieve used in step (1) is 200 mesh and the settling time is 8-12 hours.

[0014] Preferably, the concentration of the oxalic acid aqueous solution in step (2) is 0.25-2 mol / L.

[0015] More preferably, the concentration of the oxalic acid aqueous solution is 1-2 mol / L.

[0016] Preferably, the vacuum degree of vacuum drying in steps (1) and (4) is -0.08 to -0.10 MPa, the temperature is 50-70℃, and the time is 8-12h.

[0017] This invention also provides an application of a microcystin degrading agent in the degradation of organic polluted wastewater.

[0018] Preferably, the pollutants in the organic wastewater are one or more of algal organic matter, algal toxins, or antibiotics.

[0019] More preferably, the algal organic matter and algal toxins are derived from Microcystis aeruginosa, and the antibiotic is cefazolin sodium.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. By soaking the natural mineral siderite in oxalic acid solution at 60℃, oxalic acid was incorporated onto the surface of the siderite, resulting in a degrading agent capable of degrading organic pollutants in water. The preparation method is simple, efficient, and the raw materials are readily available, making it suitable for large-scale application.

[0022] 2. The degradation agent prepared by this invention can degrade pollutants in water, namely microcystin (MC_LR) and antibiotic pollutant, cefazolin sodium, under dark conditions. The degradation rate of MC_LR can reach more than 93% within 26 hours, and the degradation rate of cefazolin sodium can reach more than 93% within 10 hours. It can be widely used in the field of wastewater treatment. Since the degradation reaction does not require photocatalysis and the reaction pH can be within the range of 5-9, it has a wide pH range and can be widely promoted and applied. At the same time, it effectively saves the increased costs caused by photocatalyst conditions and pH adjustment. Attached Figure Description

[0023] Figure 1 The figures show the kinetic curves of MC_LR degradation in siderite modified with oxalic acid, glycine, citric acid, acetic acid, and oxalic acid, and unmodified siderite, respectively, in Example 1. In the figures, C represents the MC_LR content during the process, and C0 represents the initial MC_LR content.

[0024] Figure 2 The figure shows the degradation kinetics curves of MC_LR by S-OA1 degrader under different pH conditions in Example 4. In the figure, C is the MC_LR content during the process and C0 is the initial MC_LR content.

[0025] Figure 3 The XRD patterns of the S-OA1 degrading agent and siderite in Example 5 are shown.

[0026] Figure 4 The IR spectra of the S-OA1 degrading agent and siderite in Example 5 are shown.

[0027] Figure 5 The image shows the zeta potential spectrum of the S-OA1 degrading agent and siderite in Example 5.

[0028] Figure 6 The figure shows the kinetic curves of MC_LR degradation by oxalic acid (OA), S and S-OA1 degrading agents in Example 5. In the figure, C is the MC_LR content during the process and C0 is the initial MC_LR content.

[0029] Figure 7 The figure shows the degradation kinetics curve of cefazolin sodium by the S-OA1 degrading agent in Example 6. In the figure, C is the cefazolin sodium content during the process and C0 is the initial cefazolin sodium content. Detailed Implementation

[0030] The technical solution of the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the contents of the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present invention without creative effort all fall within the scope of protection of the present invention.

[0031] In the following examples, the siderite (S) was obtained from the Yichang Institute of Geology and Mineral Resources (Institute 502), and its molecular composition is Fe. [II] 1.532 Mg 0.334 Mn 0.12 Ca 0.014 (CO2)2, with a ferrous atom content of 1.38% and an SSA value of 3.88m. 2 / g, pore size 7.84nm, site density 3.10site / nm 2 The pHpzc value is 4.45.

[0032] Acetic acid (AC), citric acid (CA), oxalic acid (OA), L-ascorbic acid (AS), and glycine (Gly) were all purchased from Aladdin Reagent Co., Ltd. in China.

[0033] Microcystin (MC_LR) was purchased from Express Technology Ltd. and stored at -25°C;

[0034] Cefazolin sodium (analytical grade) was purchased from Aladdin Reagent Co., Ltd., China.

[0035] The experimental conditions for dark box stirring in the following embodiments are: light intensity range of 0.15-1.46 mW / m 3 In near-dark conditions, the engine speed was 1000 rpm.

[0036] The degradation rate described in the following examples is calculated using the formula 1 - C / C0 × 100%.

[0037] Example 1: Determination of the types of organic acids

[0038] (1) Synthesis of the degrading agent

[0039] 1) After crushing the siderite, pass it through a 200-mesh sieve. Then, take the sieved siderite and mix it with water at a mass ratio of 1:100 to prepare a suspension. Let it sit overnight and allow it to settle naturally for 8 hours. Then, place it in a vacuum drying oven (vacuum degree between -0.08 and -0.10 MPa) and dry it at 60°C for 12 hours to obtain siderite powder.

[0040] 2) Take 0.5g of siderite powder and place it in 1mol / L aqueous solutions of acetic acid, citric acid, oxalic acid, L-ascorbic acid and glycine respectively. Soak at 60℃ for 2h, filter and retain the mineral precipitate;

[0041] 3) Wash the surface of the mineral precipitate repeatedly with ultrapure water (UP water) until the washing solution is neutral to obtain the mineral sample;

[0042] 4) The mineral sample obtained in step (3) is filtered and then placed in a vacuum drying oven (vacuum degree between -0.08 and -0.10 MPa) and dried at 60°C for 8 hours to obtain the degradation agent, which is labeled as S-AC degradation agent, S-CA degradation agent, S-OA degradation agent, S-AS degradation agent and S-Gly degradation agent respectively.

[0043] (2) Verification of the effect of the degradation agent:

[0044] Take 3 mL of 2 mg / L MC_LR into a 10 mL vial, and add 5 mg of S-AC degrading agent, S-CA degrading agent, S-OA degrading agent, S-AS degrading agent, S-Gly degrading agent, and unmodified siderite (S) as control groups. No substance was added to MC_LR as a blank group. The mixture was placed in a dark chamber and stirred. At certain reaction time intervals, the supernatant was collected, centrifuged, and filtered. The concentration C of MC_LR was determined by high-performance liquid chromatography (HPLC). The specific HPLC conditions for detecting MC_LR were: Waters C18 column (4.6 mm × 250 mm, particle size 10 μm), mobile phase MeOH:0.05% TFA = 65:35, flow rate 0.8 mL / min, detection temperature 35℃, and UV detection wavelength 238 nm.

[0045] Depend on Figure 1 It can be seen that after 12 hours of dark reaction, the degradation rate of MC_LR by the S-OA degrading agent reached 72.1%, while the degradation rate of MC_LR by the blank group, control group and other acid-modified degrading agents was only about 20%. This indicates that the S-OA degrading agent prepared by oxalic acid modification of siderite has a significantly increased ability to degrade MC_LR. Other organic acid modifications do not significantly improve the degradation rate of MC_LR by siderite, indicating that oxalic acid modification of siderite is the best organic acid.

[0046] Example 2: Determination of oxalic acid concentration

[0047] (1) Synthesis of the degrading agent

[0048] 1) After crushing the siderite, pass it through a 200-mesh sieve. Then, take the sieved siderite and mix it with water at a mass ratio of 1:100 to prepare a suspension. Let it sit overnight and allow it to settle naturally for 8 hours. Then, place it in a vacuum drying oven (vacuum degree between -0.08 and -0.10 MPa) and dry it at 60°C for 12 hours to obtain siderite powder.

[0049] 2) Take 0.5g of siderite powder and place it in oxalic acid aqueous solutions of 0.25mol / L, 0.5mol / L, 1.00mol / L, 1.5mol / L and 2mol / L respectively. Soak at 60℃ for 2h, filter and retain the mineral precipitate;

[0050] 3) Wash the surface of the mineral precipitate repeatedly with ultrapure water (UP water) until the washing solution is neutral to obtain the mineral sample;

[0051] 4) The mineral sample obtained in step (3) is filtered and then placed in a vacuum drying oven (vacuum degree between -0.08 and -0.10 MPa) and dried at 60°C for 8 hours to obtain the degradation agent, which is labeled as S-OA. 0.25 Degrading agent, S-OA 0.5 Degrading agent, S-OA1 degrading agent, S-OA 1.5 Degrading agents and S-OA2 degrading agents.

[0052] (2) Verification of the effect of the degradation agent:

[0053] Take 3 mL of 2 mg / L MC_LR into a 10 mL vial, and add 5 mg of S-OA to each vial. 0.25 Degrading agent, S-OA 0.5 Degrading agent, S-OA1 degrading agent, S-OA 1.5 The degradation agent and S-OA2 degradation agent were placed in a dark chamber and stirred for 26 hours. The supernatant was then collected, centrifuged, filtered, and the concentration of MC_LR was determined by high-performance liquid chromatography (HPLC). t The specific conditions for high-performance liquid chromatography (HPLC) detection of MC_LR are the same as in Example 1, and the detection results are shown in Table 1:

[0054] Table 1. Degradation rate of MC_LR by S-OA degrading agents prepared from siderite modified with different concentrations of oxalic acid.

[0055] Oxalic acid concentration (mol / L) 0.25 0.5 1 1.5 2 Degradation rate 75.5％ 67.8％ 93.9％ 85.8％ 85.3％

[0056] As shown in Table 1, increasing the oxalic acid concentration from 0.25 mol / L to 0.5 mol / L actually decreased the degradation rate of MC_LR. This is because excess oxalic acid occupies active sites on the catalyst surface, hindering the reaction. Further increases in oxalic acid concentration lead to the removal of impurities due to increased acidity, thus increasing the degradation rate. However, with continued increases in oxalic acid concentration, excessive chelating agents are generated, increasing competition for the active material and hindering the degradation of MC_LR. Therefore, the optimal oxalic acid concentration is 1 mol / L, and after 26 hours, the S-OA1 degradation agent achieved a degradation rate of 93.9% for MC_LR.

[0057] Example 3: Effect of Degrading Agent Dosage on MC_LR Degradation Rate

[0058] Take 3 mL of 2 mg / L MC_LR into a 10 mL vial, and add 1 mg, 2 mg, 5 mg, 10 mg, and 20 mg of the S-OA1 degrading agent prepared in Example 2, respectively. Place the vials in a dark chamber and stir to react. After 12 h of reaction, collect the supernatant, centrifuge and filter. Determine the concentration C of MC_LR using high-performance liquid chromatography (HPLC). The specific conditions for HPLC detection of MC_LR are the same as in Example 1. The detection results are shown in Table 2.

[0059] Table 2. Effect of different amounts of degrading agent on degradation rate

[0060]

[0061]

[0062] As shown in Table 2, with the increase of the amount of degrading agent, the degradation rate of MC_LR by S-OA1 degrading agent showed a trend of first increasing and then gradually decreasing. The optimal oxalic acid concentration was 5 / 3 g / L, and the degradation rate of MC_LR by S-OA1 degrading agent reached 59.5% after 12 h.

[0063] Example 4: Effect of reaction pH on degradation rate during degradation

[0064] Take 3 mL of 2 mg / L MC_LR into a 10 mL vial, adjust the pH of the solution to 5, 6, 7, 8 and 9 respectively with 0.1 M NaOH solution and HClO4 solution, then add 5 mg of the S-OA1 degradation agent prepared in Example 2, place in a dark chamber and stir to react, take the supernatant at certain reaction time intervals, centrifuge and filter, and determine the concentration C of MC_LR by high performance liquid chromatography; the specific conditions for high performance liquid chromatography detection of MC_LR are the same as in Example 1.

[0065] The results are as follows Figure 2As shown, the S-OA1 degrading agent exhibits excellent degradation of MC_LR within a pH range of 5-9, indicating that the S-OA1 degrading agent can degrade MC_LR over a wide pH range, with pH 8 showing the best degradation rate.

[0066] Example 5: Effect of S-OA degrading agent, siderite, and oxalic acid on the degradation rate of MC_LR

[0067] (1) Synthesis of degradation agents under optimal conditions

[0068] 1) After crushing the siderite, pass it through a 200-mesh sieve. Then, take the sieved siderite and mix it with water at a mass ratio of 1:100 to prepare a suspension. Let it sit overnight and allow it to settle naturally for 8 hours. Then, place it in a vacuum drying oven (vacuum degree between -0.08 and -0.10 MPa) and dry it at 60°C for 12 hours to obtain siderite powder.

[0069] 2) Take 0.5g of siderite powder and place it in a 1mol / L oxalic acid aqueous solution. Soak it at 60℃ for 2h, filter and retain the mineral precipitate;

[0070] 3) Wash the surface of the mineral precipitate repeatedly with ultrapure water (UP water) until the washing solution is neutral to obtain the sample;

[0071] 4) The sample obtained in step (3) is filtered and then placed in a vacuum drying oven (vacuum degree between -0.08 and -0.10 MPa) and dried at 60°C for 8 hours to obtain the degradation agent, which is labeled as S-OA1 degradation agent. XRD analysis, IR analysis and Zeta potential analysis are performed on the S-OA1 degradation agent.

[0072] XRD analysis results of S-OA1 degrading agent and siderite are as follows: Figure 3 As shown: the peaks at 2θ values ​​of 18.4°, 22.8°, 34.2°, 42.6° and 48.1° can be attributed to the crystal planes (202), (004), (022), (224) and (026) of β-FeC2O4 (JCPDS No. 22-0635); the peaks at 2θ values ​​of 24.7°, 31.9°, 50.2° and 52.9° can be attributed to the crystal planes (012), (104), (024) and (116) of FeCO3, the main component in siderite (JCPDS No. 12-0531); the peaks at 2θ values ​​of 20.9°, 26.6° and 36.5° can be attributed to SiO2, another component in siderite. The results confirm that oxalic acid and siderite were successfully combined after acid modification, and the degradation agent was successfully prepared.

[0073] Using pristine siderite as a control, IR spectral analysis of the S-OA1 degrading agent revealed a value of 1615.74 cm⁻¹. -1The absorption of the double bond is attributed to the antisymmetric tensile vibration of C=O, 1358.87 cm. -1 1312.89cm -1 and 817.20cm -1 The absorption of tensile and flexural vibrations by OCO at the surface of the oxalic acid composite on the siderite surface (1021.02 cm⁻¹) is attributed to this. -1 Some literature reports that this is a vibrational peak in Si-O, and the peak at 1417.7 cm⁻¹ is... -1 and 866.69cm -1 This is attributed to CO3. 2- The tensile vibration absorption disappears in the S-OA1 degrading agent, and is replaced by C2O4. 2- CO3 replaced the surface of the siderite 2- 3000–3500cm -1 The broadband range is attributed to the ν of H2O. O-H ( Figure 4 ).

[0074] By comparing the Zeta potential spectra of siderite and the S-OA1 degrading agent, it was found that the isoelectric point (IEP) of siderite is pH 4.22. For the S-OA1 degrading agent, the IEP decreases sharply, and the Zeta potential shifts negatively. This is because oxalic acid is adsorbed on the siderite surface, and the introduction of carboxyl groups (-COOH) shifts the electrode towards the negative electrode. Figure 5 ).

[0075] (2) Verification of the effect of the degradation agent:

[0076] Take 3 mL of 2 mg / L MC_LR in a 10 mL vial, add 5 mg of S-OA1 degrading agent, siderite (S), and oxalic acid (OA, 1 mol / L), and adjust the pH to 8. Place the vial in a dark chamber and stir to react. At certain reaction time intervals, take the supernatant, centrifuge and filter, and determine the concentration C of MC_LR using high performance liquid chromatography. t Meanwhile, no substance was added to MC_LR as a blank group; the specific conditions for high performance liquid chromatography detection of MC_LR were the same as in Example 1.

[0077] The results are as follows Figure 6 As shown, the content of MC_LR in the blank group remained basically unchanged over time. However, compared with oxalic acid and siderite alone, the synthesized S-OA1 degrading agent showed higher degradation efficiency, with a degradation rate of 93.9% for MC_LR after 26 hours.

[0078] Example 6: Degradation experiment of cefazolin sodium by S-OA1 degrading agent

[0079] (1) Preparation of cefazolin sodium solution: Take 10 mg of cefazolin sodium (analytical grade) in a beaker, dissolve it in RO water and make up to 1 L in a volumetric flask. The concentration of cefazolin sodium obtained is 10 mg / L.

[0080] (2) Take 10 mL of the cefazolin sodium solution prepared in step (1) into a 15 mL centrifuge tube, add 10 mg of S-OA1 degradation agent, shake in a shaker (in the dark), take the supernatant at a certain reaction time interval, centrifuge and filter, and retain the filtrate; the temperature in the shaker is 55℃ and the rotation speed is 25.0 r / min;

[0081] (3) The concentration C of cefazolin sodium in the filtrate was determined by high performance liquid chromatography (HPLC). Specific conditions for HPLC detection of cefazolin sodium: An Agilent 1220 (USA) chromatograph equipped with a UV detector was used. A Kromasil 100-C18 column (250 mm × 4.6 mm, 5 μm) was used with isocratic elution. The mobile phase was 68%:32% of a 0.5% formic acid aqueous solution and acetonitrile. The column temperature was maintained at 30.00℃, and the flow rate was 1.00 mL / min. -1 The injection volume was 20.00 μL, and the detection wavelength was λ. max =275nm.

[0082] The results are as follows Figure 7 As shown, the S-OA1 degrading agent achieved a removal rate of 93.9% for cefazolin sodium after 10 hours of dark reaction, indicating that the degrading agent also has a significant degradation ability for common antibiotic pollutants in water.

Claims

1. A method for preparing a microcystin degrading agent in water, characterized in that: Includes the following steps: (1) Siderite is crushed, sieved, settled and vacuum dried to obtain siderite powder; (2) Place the siderite powder in an oxalic acid aqueous solution and soak it at 60°C for 2-3 hours. Filter and retain the precipitate. (3) Wash the precipitate with water multiple times until the washing solution is neutral to obtain a mineral sample; (4) The sample obtained in step (3) is filtered and vacuum dried to obtain a microcystin degrading agent in water.

2. The preparation method according to claim 1, characterized in that: The sieve used in step (1) is 200 mesh, and the settling time is 8-12 hours.

3. The preparation method according to claim 1, characterized in that: The concentration of the oxalic acid aqueous solution in step (2) is 0.25-2 mol / L.

4. The preparation method according to claim 3, characterized in that: The concentration of the oxalic acid aqueous solution is 1-2 mol / L.

5. The preparation method according to claim 1, characterized in that: The vacuum degree of vacuum drying in steps (1) and (4) is -0.08 to -0.10 MPa, the temperature is 50-70℃, and the time is 8-12h.

6. The application of the microcystin degrading agent prepared by the method of any one of claims 1-5 in the degradation of organic polluted wastewater.

7. The application according to claim 6, characterized in that: The pollutants in the organic wastewater are one or more of algal organic matter, algal toxins, or antibiotics.

8. The application according to claim 7, characterized in that: The algal organic matter and algal toxins were derived from Microcystis aeruginosa, and the antibiotic was cefazolin sodium.

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