Pyrite Fenton-like catalyst, preparation method thereof and application of pyrite Fenton-like catalyst in red tide treatment

Abstract

The invention discloses a pyrite Fenton-like catalyst, a preparation method thereof and application of the pyrite Fenton-like catalyst in red tide governance, and the preparation method comprises the following steps: under an anaerobic condition, adding ferrite, sodium sulfide, elemental sulfur and polyvinylpyrrolidone into an aqueous solution, and uniformly stirring to obtain a reaction solution; and carrying out hydrothermal reaction on the reaction liquid, collecting precipitate, washing and drying to obtain the pyrite Fenton-like catalyst. In the reaction process, PVP can form a barrier effect in the growth process of FeS2, inhibit aggregation of FeS2 and form stably dispersed FeS2 with a micron structure, the size of the FeS2 is similar to that of algae cells, the catalytic activity of FeS2 is remarkably improved, interaction between FeS2 and the algae cells is facilitated, and efficient removal of various red tide algae can be achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of red tide control, and specifically relates to a pyrite-based Fenton catalyst, a preparation method thereof, and an application thereof in red tide control. Background Art

[0002] Harmful algal blooms are abnormal ecological phenomena caused by the explosive growth of plankton in water bodies under certain conditions, including blue algae, diatoms, green algae, dinoflagellates, golden algae, etc. In seawater, harmful algal blooms can cause seawater to change color, which is called red tide. Red tide algae can consume a large amount of dissolved oxygen by aggregating and adhering, or accumulate in the environment or in the body of the ingestor by producing algal toxins, causing serious impacts on the safety of nuclear power cooling sources, aquaculture and tourism.

[0003] Advanced oxidation technology is an emerging environmental remediation technology that can generate reactive oxygen species such as hydroxyl radicals and sulfate radicals by activating oxidants such as hydrogen peroxide, persulfate, and percarbonate. These reactive oxygen species can interact with algal cell membranes and change the activity state of algal cells, making them suitable for emergency disposal of red tide algae. Ultraviolet, ultrasound, heating, transition metals, etc. are commonly used activation methods in advanced oxidation technology. Among them, iron-based minerals have attracted attention because of their wide sources and the lack of need for additional energy input. Pyrite is the most abundant pyrite mineral in the earth's crust. It can provide electrons for the breaking of oxygen-oxygen bonds and regulate the circulation process of ferrous ions and ferric ions, which is conducive to the continuous generation of reactive species. However, natural pyrite contains a large amount of impurities and has problems such as insufficient surface reaction activity, slow dissolution rate, and low catalytic activity at high pH, ​​which limits its application in the field of emergency disposal of red tides. Summary of the invention

[0004] The purpose of the present application is to provide a pyrite-based Fenton catalyst and a preparation method and application thereof, so as to solve the technical problems existing in the prior art that natural pyrite contains a large amount of impurities, insufficient surface reaction activity, slow dissolution rate, and low catalytic activity at high pH, ​​which limits its application in red tide emergency treatment.

[0005] In order to achieve the above-mentioned object, the first aspect of the present application provides a method for preparing a pyrite-based Fenton catalyst, comprising:

[0006] Under anaerobic conditions, ferrous salt, sodium sulfide, sulfur and polyvinyl pyrrolidone are added into the aqueous solution and stirred evenly to obtain a reaction solution;

[0007] The reaction solution is subjected to a hydrothermal reaction, and then the precipitate is collected, washed and dried to obtain a Fenton-like catalyst.

[0008] In one or more embodiments, the molecular weight of the polyvinyl pyrrolidone is 1,000 to 100,000.

[0009] In one or more embodiments, in the reaction solution, the molar ratio of the ferrous salt, sodium sulfate and elemental sulfur is (1.5-3): (1.5-3): (2-5).

[0010] In one or more embodiments, in the reaction solution, the ferrous salt includes one or more combinations of ferrous sulfate, ferrous chloride and ferrous nitrate.

[0011] In one or more embodiments, the mass ratio of the ferrous salt to polyvinyl pyrrolidone is (1.5-2.5):1.

[0012] In one or more embodiments, in the step of subjecting the reaction solution to a hydrothermal reaction, the temperature of the hydrothermal reaction is 180 to 220° C., and the time of the hydrothermal reaction is 12 to 36 hours.

[0013] In order to achieve the above-mentioned purpose, the second aspect of the present application provides a pyrite-based Fenton catalyst prepared by the preparation method described in any of the above-mentioned embodiments.

[0014] In order to achieve the above-mentioned purpose, the third aspect of the present application provides an application of the pyrite Fenton catalyst described in any of the above-mentioned embodiments in red tide control.

[0015] In one or more embodiments, the pyrite-based Fenton catalyst and the oxidant are added to the red tide algae solution and allowed to stand to inactivate the algae cells and flocculate, and the algae cells are naturally sedimented while the cell membrane remains intact, thereby achieving effective removal of the red tide algae.

[0016] In one or more embodiments, the oxidant includes one or more combinations of hydrogen peroxide, sodium persulfate, sodium persulfate, and sodium percarbonate;

[0017] In the red tide algae liquid, the concentration of the Fenton-like catalyst is 0.05-1 g / L, the concentration of the oxidant is 0.2-4 mM; and the natural sedimentation time is 3-6 hours.

[0018] In one or more embodiments, the red tide algae liquid includes one or more combinations of Phaeocystis sphericalensis, Heterosigma akashiwo, Prorocentrum donghaiense and Karenia mikimotoi, and the concentration of the red tide algae liquid is (0.5-5)×10 9 cells / L.

[0019] Different from the prior art, the beneficial effects of this application are:

[0020] The present application prepares a pyrite-based Fenton catalyst by a hydrothermal method, and by adding PVP, PVP can form a barrier effect in the growth process of FeS2 during the reaction process, inhibit the aggregation of FeS2, and form a stably dispersed FeS2 with a micron structure, and its size is similar to that of algae cells, which significantly improves the catalytic activity of FeS2 and is beneficial to the interaction between FeS2 and algae cells. It can achieve efficient removal of various red tide algae and help improve the effect of red tide control.

[0021] When the pyrite-based Fenton catalyst and oxidant of the present application are added to the red tide algae liquid, FeS2 can activate the oxidant to produce active oxygen species such as hydroxyl radicals (·OH) and sulfate radicals (SO4·-). These active oxygen species can interact with the algae cell membrane to inactivate the algae cells while ensuring the integrity of the cell membrane of the algae cells to avoid the overflow of intracellular toxins. The inactivated algae cells can flocculate and settle following the natural sedimentation process of FeS2, thereby achieving the removal of the algae cells.

[0022] The pyrite Fenton catalyst of the present application can effectively remove various algal cells in the algal liquid. For a single spherical brown cyst algae liquid, the algal cell removal rate can reach 95.9%, for a single Prorocentrum donghaiense liquid, the algal cell removal rate can reach 90.2%, for a single Heterosigma akashiwo, the algal cell removal rate can reach 96.9%, and for a mixed algal liquid of spherical brown cyst algae, Prorocentrum donghaiense, and Karenia mikimotoi, the removal rates of the three algal cells can all reach more than 80%, among which the removal efficiency of Prorocentrum donghaiense can reach 98.3%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a schematic flow chart of an implementation method of a method for preparing a pyrite-based Fenton catalyst of the present application;

[0025] Figure 2 is a SEM image of the pyrite-based Fenton catalyst of Example 1;

[0026] Figure 3 is a SEM image of the pyrite-type Fenton catalyst of Comparative Example 1;

[0027] Figure 4 is a data graph of the removal rate of Phaeocystis sphericalensis by the pyrite-type Fenton catalyst of Example 1 at different concentrations;

[0028] Figure 5 is a data graph of the removal rate of Phaeocystis sphericalensis by the pyrite-type Fenton catalyst of Comparative Example 1 with different concentrations;

[0029] Figure 6 This is a flow cytometric analysis data diagram of the removal of Phaeocystis spherica by the sodium persulfate system activated by the pyrite-type Fenton catalyst in Example 1;

[0030] Figure 7 is a data diagram of the removal rate of Prorocentrum donghaiense by the pyrite-type Fenton catalyst of Example 1 at different concentrations;

[0031] Figure 8 is a data graph showing the removal rate of Heterosigma akashiwo using the pyrite-based Fenton catalyst of Example 1 at different concentrations;

[0032] Fig. 9 This is a data graph showing the removal rate of composite red tide algae by the pyrite-based Fenton catalyst of Example 1. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application.

[0034] In order to mitigate the adverse effects of red tide outbreaks, a variety of scientific and technological approaches have been used for emergency disposal, such as physical salvage, heavy metal flocculation, modified clay, plant extracts, and advanced oxidation. However, due to high application costs, long repair cycles, and large environmental side effects, some technologies cannot be applied to actual red tide emergency disposal. More importantly, chemical remediation methods often damage the algal cell membrane, causing a large amount of intracellular toxins to overflow and cause secondary environmental pollution. Advanced oxidation technology is an emerging environmental remediation technology that can activate oxidants such as hydrogen peroxide, persulfate, and percarbonate to produce reactive oxygen species such as hydroxyl radicals (·OH) and sulfate radicals (SO4·-). These reactive oxygen species can interact with the algal cell membrane, change the active state of the algal cells, and are suitable for emergency disposal of red tide algae.

[0035] Pyrite is the most abundant pyrite mineral in the earth's crust. It can provide electrons for the breaking of oxygen-oxygen bonds and regulate the cycle of ferrous ions and ferric ions, which is conducive to the continuous generation of reactive species. Therefore, in theory, the advanced oxidation process based on pyrite catalysis can be applied to red tide control. However, natural pyrite contains a large amount of impurities and has problems such as insufficient surface reaction activity, slow dissolution rate, and low catalytic activity at high pH, ​​which limits its application in the field of red tide emergency disposal.

[0036] In order to solve the above problems, the applicant has developed a pyrite-based Fenton catalyst. Compared with natural pyrite, this pyrite effectively regulates the morphology and size, improves the catalytic activity of the material, the sample size is similar to the algae cell size, and has good dispersibility, which is conducive to the interaction with the algae cells. When used in red tide control, it is beneficial to the inactivation and flocculation sedimentation of red tide algae.

[0037] Specifically, see Figure 1 , Figure 1 It is a schematic flow chart of an implementation method of a method for preparing a pyrite-based Fenton catalyst of the present application.

[0038] like Figure 1 As shown, the preparation method comprises:

[0039] S100. Under anaerobic conditions, ferrous salt, sodium sulfide, sulfur and polyvinyl pyrrolidone are added to the aqueous solution, stirred evenly, to obtain a reaction solution.

[0040] Among them, anaerobic conditions can be achieved by continuous inert gas.

[0041] In one embodiment, in the reaction solution, the molar ratio of ferrous salt, sodium sulfate and sulfur element may be (1.5-3): (1.5-3): (2-5).

[0042] Preferably, the molar ratio of ferrous salt, sodium sulfate and elemental sulfur can be 2:2:3.

[0043] In one embodiment, the molecular weight of polyvinylpyrrolidone (PVP) may be 1,000 to 100,000.

[0044] Preferably, the molecular weight of polyvinylpyrrolidone (PVP) may be 40,000-60,000.

[0045] In one embodiment, the mass ratio of ferrous salt to PVP may be (1.5-2.5):1.

[0046] In one embodiment, the ferrous salt may be one or more combinations of ferrous sulfate, ferrous chloride and ferrous nitrate.

[0047] S200, subjecting the reaction solution to a hydrothermal reaction, and then collecting the precipitate, washing and drying it to obtain a pyrite-based Fenton catalyst.

[0048] In one embodiment, the temperature of the hydrothermal reaction may be 180 to 220° C., and the time of the hydrothermal reaction may be 12 to 36 hours.

[0049] In one embodiment, the precipitate may be washed by multiple washings with ultrapure water and ethanol to remove unreacted substances.

[0050] Based on the preparation methods of the above-mentioned embodiments, PVP, as a low-toxic and biocompatible organic molecule, can form a barrier effect in the growth process of FeS2 during the reaction process, inhibit the aggregation of FeS2, and form a stable and dispersed FeS2 with a micron structure, and its size is similar to that of algae cells, which significantly improves the catalytic activity of FeS2 and is beneficial to the interaction between FeS2 and algae cells. It can achieve efficient removal of a variety of red tide algae and help improve the effect of red tide control.

[0051] The present application also provides an application of a pyrite-based Fenton catalyst prepared by any of the above-mentioned embodiments in red tide control.

[0052] Specifically, in the control of red tides, the above-mentioned pyrite-like Fenton catalyst and oxidant can be added to the red tide algae liquid. The Fenton-like catalyst can activate the oxidant to produce active oxygen species such as hydroxyl radicals (·OH) and sulfate radicals (SO4·-). These active oxygen species can interact with the algae cell membrane to inactivate the algae cells, while ensuring the integrity of the cell membrane of the algae cells and avoiding the overflow of intracellular toxins.

[0053] By leaving the red tide algae liquid to stand, the inactivated algae cells can flocculate and settle following the natural sedimentation process of FeS2, thereby achieving algae cell removal.

[0054] Specifically, the above-mentioned red tide control is effective for a variety of red tide algae such as spherical brown cysts, red tide heterosigmus, and mikimoto's Karenia. The red tide algae liquid may include one or more combinations of spherical brown cysts, red tide heterosigmus, and mikimoto's Karenia. In one embodiment, the concentration of the red tide algae liquid may be (0.5-5)×10 9 cells / L.

[0055] In one embodiment, in order to optimize the treatment effect, the concentration of the Fenton-like catalyst in the red tide algae liquid can be 0.05-1 g / L, and the concentration of the oxidant can be 0.2-4 mM.

[0056] In one embodiment, the oxidizing agent may include one or more combinations of hydrogen peroxide, sodium persulfate, sodium hydrogen persulfate, and sodium percarbonate.

[0057] In one embodiment, the natural sedimentation time may be 4 to 6 hours.

[0058] The effects of the technical solution of the present application are further elaborated in detail below in conjunction with specific embodiments.

[0059] Embodiment 1:

[0060] A pyrite-based Fenton catalyst is prepared by the following steps:

[0061] Take 60 mL of ultrapure water in a beaker and pre-pass argon for 30 minutes to remove dissolved oxygen in the water; add 4 mM ferrous sulfate and 0.6 g PVP (molecular weight = 58,000) into the water and start stirring. During the stirring process, pass argon throughout to avoid oxidation of ferrous ions; then, add 4 mM sodium sulfide and 6 mM sulfur to the reaction solution, and continue stirring for 30 minutes.

[0062] After being fully mixed, the reaction solution was transferred to a high-pressure reactor and reacted in a constant temperature box with air supply at 200°C for 24 hours;

[0063] After the reaction is completed, the mixture is cooled to room temperature, and the black precipitate is collected by centrifugation. It is washed 2 to 3 times with ultrapure water and ethanol respectively, and then vacuum dried to obtain a PVP-FeS2 Fenton catalyst.

[0064] Comparative Example 1:

[0065] A pyrite-based Fenton catalyst is prepared by the following steps:

[0066] Take 60 mL of ultrapure water in a beaker and pre-pass argon gas for 30 minutes to remove dissolved oxygen in the water; add 4 mM ferrous sulfate into the water and start stirring. During the stirring process, pass argon gas throughout to avoid oxidation of ferrous ions; then, add 4 mM sodium sulfide and 6 mM sulfur to the reaction solution and continue stirring for 30 minutes.

[0067] After being fully mixed, the reaction solution was transferred to a high-pressure reactor and reacted in a constant temperature box with air supply at 200°C for 24 hours;

[0068] After the reaction is completed, the mixture is cooled to room temperature, and the black precipitate is collected by centrifugation. It is washed 2 to 3 times with ultrapure water and ethanol respectively, and then dried under vacuum to obtain a FeS2-type Fenton catalyst.

[0069] Effect example 1:

[0070] The Fenton-like catalysts prepared in Example 1 and Comparative Example 1 were characterized and analyzed to obtain Figure 2 and Figure 3 , Figure 2 is a SEM image of the pyrite Fenton catalyst of Example 1, Figure 3 This is the SEM image of the pyrite-type Fenton catalyst of Comparative Example 1.

[0071] like Figure 2 and Figure 3 As shown, the pyrite-based Fenton catalyst of Comparative Example 1 presents an irregularly aggregated block structure with a size greater than 10 μm, which results in a reduction in the surface active area, affects the surface reaction rate, and results in lower catalytic activity.

[0072] The pyrite Fenton catalyst of Example 1 presents a uniform micron spherical structure and has good dispersibility, which is mainly due to the barrier effect formed by PVP during the growth of FeS2, which inhibits the aggregation of FeS2. The micron spherical structure with good dispersibility significantly increases the surface active area and helps to improve the dispersion performance of the catalyst. In addition, the diameter of the micron spherical structure is about 0.3 to 2.2 μm, which is similar to the size of algae cells, which is conducive to the interaction between FeS2 and algae cells, significantly improves the catalytic activity, and helps to improve the treatment effect.

[0073] Effect example 2: Spherical brown cyst algae removal experiment

[0074] The initial concentration was 1.5×10 9 cells / L of spherical brown cysts were poured into a 10L reactor, and the pyrite-based Fenton catalysts of Example 1 and Comparative Example 1 were used to carry out treatment experiments. The experimental process included:

[0075] The pyrite Fenton catalyst was dispersed in a water dispersion, and the dispersion and sodium persulfate solution were sprayed into the reactor to make the final concentrations of the pyrite Fenton catalyst 0.1 g / L, 0.2 g / L, 0.3 g / L, and 0.4 g / L, respectively, and the concentration of sodium persulfate was 0.8 mM. After standing for 4 hours, the concentration of P. sphericalis was measured, and the removal rate of algal cells was calculated to obtain Figure 4 and Figure 5 . Figure 4 is a data graph showing the removal rate of Phaeocystis sphericalensis by pyrite-type Fenton catalysts of Example 1 at different concentrations. Figure 5 It is a data graph of the removal rate of spherical brown algae by the pyrite-type Fenton catalyst of Comparative Example 1 with different concentrations.

[0076] like Figure 4 As shown, different concentrations of PVP-FeS2 Fenton catalysts have obvious removal effects on P. sphericalus, and have better removal efficiency when the concentration is greater than 0.2g / L. When the concentration of PVP-FeS2 Fenton catalyst is 0.3g / L, the removal efficiency is the highest, reaching 95.9%.

[0077] And as Figure 5As shown, when the concentration of FeS2-type Fenton catalyst is 0.3 g / L, the removal efficiency of P. sphericalis is the highest, reaching 40.7%, which is significantly weaker than the PVP-FeS2-type Fenton catalyst in Example 1.

[0078] In summary, for the same concentration of spherical brown algae liquid, when the sodium persulfate concentration is 0.8mM, compared with comparative example 1, the PVP-FeS2 of Example 1 has a higher removal efficiency for spherical brown algae, which indicates that the PVP modification increases the surface active sites of FeS2, which is conducive to promoting the activation of sodium persulfate to produce more reactive species, attacking algae cells and making them inactive. Subsequently, PVP-FeS2, which is closer to the size of algae cells, will co-flocculate and settle with the inactivated algae cells, achieving efficient removal of spherical brown algae.

[0079] Further, flow cytometry analysis was performed on the spherical brown algae liquid treated with the PVP-FeS2-type Fenton catalyst in Example 1, and the results were as follows: Figure 6 , Figure 6 This is a flow cytometric analysis data diagram of the Fenton-like catalyst activated sodium persulfate system in Example 1 for removing Phaeocystis spherica.

[0080] like Figure 6 As shown, there are basically no necrotic cells in the Q1 quadrant. During the treatment process, the apoptotic algal cells can maintain the integrity of the cell membrane, which is beneficial to avoid the overflow of intracellular toxins.

[0081] Effect example 3: Prorocentrum donghaiense removal experiment

[0082] The initial concentration was 0.5×10 9 cells / L of Prorocentrum donghaiense was poured into a 10L reactor, and the pyrite Fenton catalyst of Example 1 was used to carry out a treatment experiment. The experimental process included:

[0083] The pyrite Fenton catalyst was dispersed in a water dispersion, and the dispersion and sodium percarbonate solution were sprayed into the reactor to make the final concentrations of the pyrite Fenton catalyst 0.05 g / L, 0.1 g / L, and 0.15 g / L, respectively, and the concentration of sodium percarbonate was 0.2 mM. After standing for 3 hours, the concentration of Prorocentrum donghaiense was measured, and the removal rate of algal cells was calculated to obtain Figure 7 . Figure 7 It is a data graph of the removal rate of Prorocentrum donghaiense with different concentrations of the pyrite-type Fenton catalyst of Example 1.

[0084] like Figure 7 As shown in the figure, different concentrations of PVP-FeS2 Fenton catalysts all had obvious removal effects on Prorocentrum donghaiense. When the concentration of PVP-FeS2 Fenton catalyst was 0.15 g / L, the removal effect on Prorocentrum donghaiense was significantly better than that on Prorocentrum donghaiense with a concentration of 0.5×10 9cells / L had the highest removal efficiency, reaching 90.2%.

[0085] Effect example 4: Experiment on removing Heterosigma akashiwo

[0086] The initial concentration was 3×10 9 cells / L of Heterosigma akashiwo was poured into a 10L reactor, and the pyrite-based Fenton catalyst of Example 1 was used to carry out a treatment experiment. The experimental process included:

[0087] The pyrite Fenton catalyst was dispersed in a water dispersion, and the dispersion and sodium persulfate solution were sprayed into the reactor to make the final concentrations of the pyrite Fenton catalyst 0.3 g / L, 0.4 g / L, and 0.5 g / L, respectively, and the concentration of sodium persulfate was 2 mM. After standing for 5 hours, the concentration of Heterosigma akashiwo was measured, and the removal rate of algal cells was calculated to obtain Figure 8 . Figure 8 This is a data graph showing the removal rate of Heterosigma akashiwo at different concentrations of the pyrite-based Fenton catalyst of Example 1.

[0088] like Figure 8 As shown in the figure, different concentrations of PVP-FeS2 Fenton catalysts all had obvious removal effects on Heterosigma akashiwo. When the concentration of PVP-FeS2 Fenton catalyst was 0.4 g / L, the removal effect on the concentration of 3×10 9 cells / L had the highest removal efficiency of Heterosigma akashiwo, which could reach 96.9%.

[0089] Effect example 5: Compound red tide algae removal experiment

[0090] A mixed algae solution of Phaeocystis sphericalensis, Prorocentrum donghaiense, and Karenia mikimotoi was prepared. The initial concentration of algae cells in the mixed algae solution was 5×10 9 cells / L, the concentration ratio of Phaeocystis sphericalensis, Prorocentrum donghaiense and Karenia mikimotoi was 2:1:2. The mixed algae solution was poured into a 10L reactor, and the pyrite Fenton catalyst of Example 1 was used to carry out the treatment experiment. The experimental process included:

[0091] The pyrite Fenton catalyst was dispersed in a water dispersion, and the dispersion and hydrogen peroxide solution were sprayed into the reactor to make the final concentration of the Fenton catalyst 1g / L and the concentration of hydrogen peroxide 4mM. After that, the concentrations of the three red tide algae were measured and the removal rates were calculated respectively to obtain Fig. 9 . Fig. 9 This is a data graph showing the removal rate of composite red tide algae by the pyrite-based Fenton catalyst of Example 1.

[0092] like Fig. 9As shown, the PVP-FeS2 Fenton catalyst of Example 1 has obvious removal effect on different types of red tide algae in the mixed algae liquid, and the removal efficiency of the three types of red tide algae can reach more than 80%, among which the removal efficiency of Prorocentrum donghaiense is the highest, which can reach 98.3%.

[0093] It is obvious to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0094] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a pyrite-based Fenton catalyst, characterized in that: include: Under anaerobic conditions, ferrous salt, sodium sulfide, sulfur and polyvinyl pyrrolidone are added into the aqueous solution and stirred evenly to obtain a reaction solution; The reaction solution is subjected to a hydrothermal reaction, and then the precipitate is collected, washed and dried to obtain a pyrite-type Fenton catalyst.

2. The preparation method according to claim 1, characterized in that: The molecular weight of the polyvinyl pyrrolidone is 1,000 to 100,000.

3. The preparation method according to claim 1, characterized in that: In the reaction solution, the molar ratio of the ferrous salt, sodium sulfate and sulfur is (1.5-3): (1.5-3): (2-5).

4. The preparation method according to claim 1, characterized in that: In the reaction solution, the ferrous salt includes one or more combinations of ferrous sulfate, ferrous chloride and ferrous nitrate; and / or, The mass ratio of the ferrous salt to polyvinyl pyrrolidone is (1.5-2.5):

1.

5. The preparation method according to claim 1, characterized in that: In the step of subjecting the reaction solution to a hydrothermal reaction, the temperature of the hydrothermal reaction is 180 to 220° C., and the time of the hydrothermal reaction is 12 to 36 hours.

6. A pyrite-based Fenton catalyst prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the pyrite Fenton catalyst as claimed in claim 6 in red tide control.

8. The use according to claim 7, characterized in that: The pyrite-based Fenton catalyst and the oxidant are added to the red tide algae solution and allowed to stand to inactivate and flocculate the algae cells, and the algae cells are naturally sedimented while the cell membrane remains intact, thereby achieving effective removal of the red tide algae.

9. The use according to claim 8, characterized in that: The oxidant comprises one or more combinations of hydrogen peroxide, sodium persulfate, sodium hydrogen persulfate and sodium percarbonate; In the red tide algae liquid, the concentration of the pyrite Fenton catalyst is 0.05-1 g / L, the concentration of the oxidant is 0.2-4 mM; and the natural sedimentation time is 3-6 h.

10. The use according to claim 8, characterized in that: The red tide algae liquid comprises one or more combinations of Phaeocystis sphericalensis, Heterosigma akashiwo, Prorocentrum donghaiense and Karenia mikimotoi, and the concentration of the red tide algae liquid is (0.5-5)×10 9 cells / L.

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