Composite photoelectrocatalytic material and application thereof in algal bloom treatment

Abstract

This invention discloses a composite photoelectrocatalytic material and its application in algal bloom control, belonging to the field of water treatment technology. The composite photoelectrocatalytic material of this invention is prepared by the following method: (1) FeCo2O4 is added to NaOH solution to obtain a first solution; g-C3N4 is added to deionized water and stirred evenly to obtain a second solution; the first solution and the second solution are mixed evenly, and FeCo2O4 / g-C3N4 is prepared by hydrothermal reaction; (2) Cellulose acetate is dissolved in acetone to form a sol; FeCo2O4 / g-C3N4 is added to the sol, ultrasonically mixed, poured into a petri dish, and allowed to stand and evaporate to prepare a FeCo2O4 / g-C3N4 / CA membrane. This invention uses the FeCo2O4 / g-C3N4 / CA membrane as a composite photoelectrocatalytic material, a graphite plate as an electrode, and sodium chloride solution as an electrolyte to form a photoelectrocatalytic system, which can quickly and effectively remove green algae in water bodies and has broad application prospects in algal bloom control.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a composite photoelectrocatalytic material and its application in algal bloom control. Background Technology

[0002] The discharge of large amounts of nitrogen- and phosphorus-containing waste into water bodies has led to eutrophication, which has become one of the most critical issues in water pollution. Eutrophication not only causes a surge in phytoplankton (such as green algae, cyanobacteria, and dinoflagellates) in aquatic ecosystems, resulting in algal blooms and posing a serious threat to drinking water quality, but also reduces dissolved oxygen and water transparency, harming aquatic life and ultimately disrupting the ecological balance of the water body. Compared to cyanobacterial blooms, green algal blooms, while less intense, have a much wider impact. Green algal blooms not only absorb large amounts of nutrients from the water, reducing the living space of other aquatic species and disrupting the original ecological balance, but also cause severe economic losses to people's daily lives, tourism, and fisheries. Therefore, effectively addressing green algal blooms is of paramount importance.

[0003] Currently, traditional methods for controlling algal blooms mainly fall into three categories: physical methods, chemical methods, and biological methods. Physical methods have minimal environmental impact, but their high cost and low efficiency limit their application. Chemical methods offer advantages in high removal efficiency and low cost, but they are highly harmful to the environment. Biological methods are relatively cheaper and easier to operate than the other two, but due to their low removal rate, they are unsuitable for algal bloom outbreaks. In general, traditional algae control methods have limitations to some extent. Therefore, there is an urgent need to find an economical, safe, and efficient method for controlling algal blooms to address the challenges of algal bloom outbreaks.

[0004] Emerging photocatalysis and electrocatalysis technologies are gradually coming into focus for researchers. Photocatalytic algae removal involves exciting a semiconductor catalyst with light, which generates reactive oxygen species (ROS) with strong oxidizing capabilities. These ROS damage the physiological characteristics of algae, effectively inactivating them. However, currently used photocatalytic technologies and materials face challenges in dealing with algal blooms, including long reaction times and low algal biomass, clearly unable to handle large-scale algal blooms and severely limiting their practical application. Electrocatalysis, on the other hand, relies on the oxidation process to generate a large number of free radicals, which are primarily used to inactivate algae. While current electrocatalytic algae removal can achieve rapid algae removal in a short time, its high energy consumption and complex electrode material preparation greatly limit its practical application. Therefore, there is an urgent need for a technology that is simple to prepare, has low energy consumption, high algae removal efficiency, and can be applied to actual water bodies to replace simple photocatalysis and electrocatalysis technologies. Summary of the Invention

[0005] In view of the above-mentioned prior art, the purpose of this invention is to provide a composite photoelectrocatalytic material and its application in algal bloom control. This invention uses a FeCo2O4 / g-C3N4 / CA membrane as the composite photoelectrocatalytic material, a graphite plate as the electrode, and sodium chloride solution as the electrolyte to form a photoelectrocatalytic system (PEC). This system can rapidly and effectively remove green algae from water bodies and has broad application prospects in algal bloom control.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a composite photoelectrocatalytic material prepared by the following method:

[0008] (1) Add ferric cobalt oxide (FeCo2O4) to NaOH solution to obtain the first solution; add graphitic carbon nitride (g-C3N4) to deionized water and stir evenly to obtain the second solution; mix the first solution and the second solution evenly and prepare FeCo2O4 / g-C3N4 by hydrothermal reaction;

[0009] (2) Dissolve cellulose acetate (CA) in acetone to form a sol; add FeCo2O4 / g-C3N4 prepared in step (1) to the sol, mix with ultrasonication, pour into a petri dish, let stand to evaporate, and prepare the composite photoelectrocatalytic material (FeCo2O4 / g-C3N4 / CA membrane).

[0010] Preferably, in step (1), the FeCo2O4 is prepared by the following method:

[0011] Dissolve ferric nitrate and cobalt nitrate in deionized water and stir at 50-70℃ for 1.5-2.5 hours. Then add citric acid and continue stirring for 1.5-2.5 hours. Raise the temperature to 85-95℃ and continue stirring until a sol-like liquid is formed.

[0012] The obtained sol-like liquid was placed in a muffle furnace and calcined. The calcined solid was then ground, washed, and dried to prepare FeCo2O4.

[0013] Preferably, in step (1), the g-C3N4 is prepared by the following method:

[0014] Urea was dissolved in deionized water to obtain a urea solution; the urea solution was placed in a muffle furnace and heated to 550°C at a rate of 5°C / min, and then held at 550°C for 4 hours, and then naturally cooled to room temperature to obtain a pale yellow solid g-C3N4.

[0015] Preferably, in step (1), the amount of FeCo2O4 added is 1%-15% of the mass of g-C3N4.

[0016] Preferably, in step (1), the temperature of the hydrothermal reaction is 150-170℃ and the time of the hydrothermal reaction is 4-8h.

[0017] Preferably, in step (2), the ratio of the amount of CA to FeCo2O4 / g-C3N4 added is 5:1-1:1.

[0018] In a second aspect, the present invention provides the application of the above-described composite photoelectrocatalytic material in the removal of algae from water.

[0019] In the above applications, preferably, the algae is green algae; more preferably, the green algae is Chlorella.

[0020] A third aspect of the present invention provides a photoelectrocatalytic system for controlling algal blooms, comprising: the aforementioned composite photoelectrocatalytic material, a graphite plate electrode, and an electrolyte solution.

[0021] Preferably, the electrolyte solution is 0.1M NaCl.

[0022] A fourth aspect of the present invention provides a method for removing algae from water using the above-described photoelectrocatalytic system, comprising the following steps:

[0023] A composite photoelectrocatalytic material was added to the water to be treated. A photoelectrocatalytic system was constructed using a graphite plate as the electrode and 0.1M NaCl as the electrolyte. Under light irradiation, the photoelectrocatalytic effect was achieved by applying 2.0 mA / cm². 2 Current density is used to remove algae from water.

[0024] The beneficial effects of this invention are:

[0025] (1) The technology used in this invention is different from traditional photocatalytic algae removal technology (action time of about 6 hours, algal biomass treated 2.7×10⁻⁶). 6 Compared to electrocatalysis (current density of 50 mA / mL), this method reduces reaction time and increases treatable algal biomass. 2 -75 mA / cm 2 Compared to other methods, this reduces energy consumption and shortens the electrode preparation steps. This allows for more efficient treatment of green algal blooms and improves drinking water safety.

[0026] (2) From the perspective of the physiological characteristics of Chlorella, this invention provides a novel technology for inactivating Chlorella by combining photocatalysis and electrocatalysis in an efficient manner. The photocatalytic material is simple to prepare and has low energy consumption, thereby saving manpower, material resources and financial resources. Moreover, the composite photocatalytic material prepared by this invention can be recycled, further reducing the cost of algae removal. Attached Figure Description

[0027] Figure 1These are the XRD patterns of the FeCo2O4 / g-C3N4 composite materials prepared in Examples 1-5.

[0028] Figure 2 These are SEM images of the composite photoelectrocatalytic material (FeCo2O4 / g-C3N4 / CA film) prepared in Example 3; where a is a surface view and b is a cross-sectional view.

[0029] Figure 3 This is a graph showing the removal effect of different FeCo2O4 doping ratios during photocatalysis.

[0030] Figure 4 These are images showing the removal effects of Chlorella in different systems.

[0031] Figure 5 The images show the XRD patterns of the composite photocatalytic material (FeCo2O4 / g-C3N4 / CA film) prepared in Example 3 before and after the four reactions.

[0032] Figure 6 The images show the algae removal effect of the composite photoelectrocatalytic material (FeCo2O4 / g-C3N4 / CA membrane) prepared in Example 3 of the fourth instance.

[0033] Figure 7 These are SEM images of algae at different time points of the composite photoelectrocatalytic material (FeCo2O4 / g-C3N4 / CA membrane) prepared in Example 3; where a is the initial time; b is 90 min; and c is 180 min. Detailed Implementation

[0034] The following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0035] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.

[0036] The test materials used in the embodiments of the present invention, unless otherwise specified, are all conventional test materials in the art and can be purchased through commercial channels.

[0037] The following examples are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way.

[0038] Example 1: Preparation of composite photoelectrocatalytic materials

[0039] 1. Preparation of g-C3N4:

[0040] 125g of urea was added to 125mL of deionized water and heated in a water bath at 65℃ for 30min to dissolve. The dissolved solution was poured into a high-temperature resistant ceramic crucible and placed in a muffle furnace. The temperature was increased to 550℃ at a rate of 5℃ / min and then maintained at 550℃ for 4h. The solution was then allowed to cool naturally to room temperature to obtain a pale yellow solid g-C3N4.

[0041] 2. Preparation of FeCo2O4:

[0042] 4.04 g of ferric nitrate and 5.82 g of cobalt nitrate were dissolved in 100 mL of deionized water and heated and stirred in a 60 °C water bath for 2 h. Then, 7.56 g of citric acid was added and stirring was continued for 2 h. The water bath temperature was then increased to 90 °C to accelerate liquid evaporation, eventually forming a sol-like liquid. The obtained sol-like liquid was poured into a high-temperature resistant ceramic crucible and placed in a muffle furnace. The temperature was increased to 400 °C at a rate of 2 °C / min and then maintained at 400 °C for 2 h. The mixture was then allowed to cool naturally to room temperature. The black solid obtained after calcination was ground and washed three times alternately with deionized water and anhydrous ethanol. The product was dried in a 60 °C oven for 12 h and then ground to obtain a black powder, FeCo2O4.

[0043] 3. Preparation of FeCo2O4 / g-C3N4:

[0044] Add 0.03g of FeCo2O4 to 30mL of 0.2M NaOH solution, and label it solution A; add 3g of g-C3N4 to 70mL of deionized water and stir for 1h to form a suspension, and label it solution B.

[0045] Solution A and solution B were mixed thoroughly and transferred to a 200 mL high-pressure reactor. The mixture was subjected to hydrothermal reaction at 160 °C for 6 hours, followed by natural cooling to room temperature. The mixture was then washed alternately with deionized water and anhydrous ethanol until neutral. The product was dried in a 60 °C oven for 6 hours and then ground to obtain FeCo2O4 / g-C3N4 (labeled as "FeCo2O4 / g-C3N4-1%" based on the amount of FeCo2O4 incorporated).

[0046] 4. Preparation of composite photoelectrocatalytic materials (FeCo2O4 / g-C3N4 / CA membrane):

[0047] Add 0.5g CA and 15mL acetone to a beaker. After the CA is completely dissolved to form a transparent sol, add 0.3g FeCo2O4 / g-C3N4 to the beaker and sonicate for 4 hours to disperse the FeCo2O4 / g-C3N4 powder evenly in the solution. Pour the mixed solution into a petri dish with a diameter of 3cm. After the acetone evaporates, a FeCo2O4 / g-C3N4 / CA film will be formed, thus preparing the composite photoelectrocatalytic material (labeled as FeCo2O4 / g-C3N4 / CA-1%).

[0048] Example 2: Preparation of composite photoelectrocatalytic materials

[0049] The preparation methods for g-C3N4 and FeCo2O4 are the same as in Example 1.

[0050] Add 0.09 g of FeCo2O4 to 30 mL of 0.2 M NaOH solution, and label it solution A; add 3 g of g-C3N4 to 70 mL of deionized water and stir for 1 h to form a suspension, and label it solution B.

[0051] Solution A and solution B were mixed evenly and transferred to a 200 mL high-pressure reactor. The mixture was hydrothermally reacted at 160 °C for 6 h and then naturally cooled to room temperature. The product was washed alternately with deionized water and anhydrous ethanol until neutral. The product was then dried in a 60 °C oven for 6 h and ground to obtain FeCo2O4 / g-C3N4 (labeled as "FeCo2O4 / g-C3N4-3%" according to the amount of FeCo2O4 incorporated).

[0052] Add 0.5g CA and 15mL acetone to a beaker. After the CA is completely dissolved to form a transparent sol, add 0.3g FeCo2O4 / g-C3N4 to the beaker and sonicate for 4 hours to disperse the FeCo2O4 / g-C3N4 powder evenly in the solution. Pour the mixed solution into a petri dish with a diameter of 3cm. After the acetone evaporates, a FeCo2O4 / g-C3N4 / CA film will be formed, thus preparing the composite photoelectrocatalytic material (labeled as FeCo2O4 / g-C3N4 / CA-3%).

[0053] Example 3: Preparation of composite photoelectrocatalytic materials

[0054] The preparation methods for g-C3N4 and FeCo2O4 are the same as in Example 1.

[0055] Add 0.15g of FeCo2O4 to 30mL of 0.2M NaOH solution, and label it solution A; add 3g of g-C3N4 to 70mL of deionized water and stir for 1h to form a suspension, and label it solution B.

[0056] Solution A and solution B were mixed evenly and transferred to a 200 mL high-pressure reactor. The mixture was hydrothermally reacted at 160 °C for 6 h and then naturally cooled to room temperature. The product was washed alternately with deionized water and anhydrous ethanol until neutral. The product was then dried in a 60 °C oven for 6 h and ground to obtain FeCo2O4 / g-C3N4 (labeled as "FeCo2O4 / g-C3N4-5%" according to the amount of FeCo2O4 incorporated).

[0057] Add 0.5g CA and 15mL acetone to a beaker. After the CA is completely dissolved to form a transparent sol, add 0.3g FeCo2O4 / g-C3N4 to the beaker and sonicate for 4 hours to disperse the FeCo2O4 / g-C3N4 powder evenly in the solution. Pour the mixed solution into a petri dish with a diameter of 3cm. After the acetone evaporates, a FeCo2O4 / g-C3N4 / CA film will be formed, thus preparing the composite photoelectrocatalytic material (labeled as FeCo2O4 / g-C3N4 / CA-5%).

[0058] Example 4: Preparation of composite photoelectrocatalytic materials

[0059] The preparation methods for g-C3N4 and FeCo2O4 are the same as in Example 1.

[0060] Add 0.30g of FeCo2O4 to 30mL of 0.2M NaOH solution, and label it solution A; add 3g of g-C3N4 to 70mL of deionized water and stir for 1h to form a suspension, and label it solution B.

[0061] Solution A and solution B were mixed evenly and transferred to a 200 mL high-pressure reactor. The mixture was hydrothermally reacted at 160 °C for 6 h and then naturally cooled to room temperature. The product was washed alternately with deionized water and anhydrous ethanol until neutral. The product was then dried in a 60 °C oven for 6 h and ground to obtain FeCo2O4 / g-C3N4 (labeled as "FeCo2O4 / g-C3N4-10%" according to the amount of FeCo2O4 incorporated).

[0062] Add 0.5g CA and 15mL acetone to a beaker. After the CA is completely dissolved to form a transparent sol, add 0.3g FeCo2O4 / g-C3N4 to the beaker and sonicate for 4 hours to disperse the FeCo2O4 / g-C3N4 powder evenly in the solution. Pour the mixed solution into a petri dish with a diameter of 3cm. After the acetone evaporates, a FeCo2O4 / g-C3N4 / CA film will be formed, thus preparing the composite photoelectrocatalytic material (labeled as FeCo2O4 / g-C3N4 / CA-10%).

[0063] Example 5: Preparation of composite photoelectrocatalytic materials

[0064] The preparation methods for g-C3N4 and FeCo2O4 are the same as in Example 1.

[0065] Add 0.45g of FeCo2O4 to 30mL of 0.2M NaOH solution, and label it solution A; add 3g of g-C3N4 to 70mL of deionized water and stir for 1h to form a suspension, and label it solution B.

[0066] Solution A and solution B were mixed evenly and transferred to a 200 mL high-pressure reactor. The mixture was hydrothermally reacted at 160 °C for 6 h and then naturally cooled to room temperature. The product was washed alternately with deionized water and anhydrous ethanol until neutral. The product was then dried in a 60 °C oven for 6 h and ground to obtain FeCo2O4 / g-C3N4 (labeled as "FeCo2O4 / g-C3N4-15%" according to the amount of FeCo2O4 incorporated).

[0067] Add 0.5g CA and 15mL acetone to a beaker. After the CA is completely dissolved to form a transparent sol, add 0.3g FeCo2O4 / g-C3N4 to the beaker and sonicate for 4 hours to disperse the FeCo2O4 / g-C3N4 powder evenly in the solution. Pour the mixed solution into a petri dish with a diameter of 3cm. After the acetone evaporates, a FeCo2O4 / g-C3N4 / CA film will be formed, thus preparing the composite photoelectrocatalytic material (labeled as FeCo2O4 / g-C3N4 / CA-15%).

[0068] Comparative Example 1: Preparation of g-C3N4 / CA membrane

[0069] The preparation method of g-C3N4 is the same as in Example 1.

[0070] Add 0.5g CA and 15mL acetone to a beaker. After the CA is completely dissolved, a transparent sol is formed. Add 0.3g g-C3N4 to the beaker and sonicate for 4 hours to disperse the g-C3N4 powder evenly in the solution. Pour the mixed solution into a petri dish with a diameter of 3cm. After the acetone evaporates, a g-C3N4 / CA film will be formed.

[0071] Comparative Example 2: Preparation of FeCo2O4 / CA membrane

[0072] The preparation method of FeCo2O4 is the same as in Example 1.

[0073] Add 0.5g CA and 15mL acetone to a beaker. After the CA is completely dissolved, a transparent sol is formed. Add 0.3g FeCo2O4 to the beaker and sonicate for 4 hours to disperse the FeCo2O4 powder evenly in the solution. Pour the mixed solution into a petri dish with a diameter of 3cm. After the acetone evaporates, a FeCo2O4 / CA film will be formed.

[0074] Experimental Example 1: Structural Characterization of Composite Photoelectrocatalytic Materials

[0075] 1. XRD characterization of FeCo2O4 / g-C3N4:

[0076] The FeCo2O4 / g-C3N4 prepared in Examples 1-5 were characterized by XRD, and the results are as follows: Figure 1As shown, the results indicate that no other impurity peaks appeared in either g-C3N4 or FeCo2O4, indicating high material purity. Furthermore, the XRD pattern of FeCo2O4 / g-C3N4 included characteristic peaks of both g-C3N4 and FeCo2O4, and the peak value at 36.2° significantly increased with increasing FeCo2O4 percentage mass. In conclusion, the XRD results demonstrate the successful preparation of FeCo2O4 / g-C3N4.

[0077] 2. SEM characterization of the composite photoelectrocatalytic material:

[0078] The cross-section and surface of the composite photoelectrocatalytic material prepared in Example 3 were observed by scanning electron microscopy (SEM), and the results are as follows: Figure 2 As shown, the results indicate that both its surface and cross-section exhibit excellent uniform layered structure, which suggests that CA has good cross-linking properties.

[0079] Experimental Example 2: Performance Evaluation of Composite Photocatalytic Materials for Removing Chlorella

[0080] 1. Test method:

[0081] The photocatalytic performance of the materials prepared in Examples 1-5 and Comparative Examples 1-2 in removing Chlorella was investigated. The photocatalytic process was carried out in a photochemical reactor. 6 × 10⁶ μL of [material name missing] was added to the reactor. 6 100 mL of Chlorella cells / mL was used in a FeCo₂O₄ / g-C₃N₄ / CA membrane (d = 3 cm) with a 350W xenon lamp as the light source. The reaction time was 180 min. 4 mL of algal solution was taken at fixed intervals, and the algal removal rate was analyzed using a UV-Vis spectrophotometer. The removal rate formula is as follows:

[0082]

[0083] In the formula, R is the algal cell removal rate, %; C0 and C t represents the initial chlorophyll a concentration and the chlorophyll a concentration at time t, respectively, in mg / L.

[0084] 2. Test Results:

[0085] Depend on Figure 3 As can be seen from the results, in the experimental group under pure light conditions, the chlorophyll a content decreased rapidly in the first 20 minutes and then tended to stabilize. This may be due to the stress of algae to the new environment and the ultraviolet light irradiation of the xenon lamp. FeCo2O4 / g-C3N4 / CA-5% showed the best photocatalytic degradation performance, with a chlorophyll a degradation rate of 48.73% after 180 minutes.

[0086] from Figure 3As shown in b, the removal rate of chlorophyll a by FeCo2O4 / g-C3N4 / CA-5% was higher than that of g-C3N4 / CA (39.53%) and FeCo2O4 / CA (33.14%), indicating improved removal efficiency. This demonstrates that combining g-C3N4, FeCo2O4, and CA membranes can significantly improve the removal effect on Chlorella, exhibiting a synergistic effect.

[0087] In summary, the FeCo2O4 / g-C3N4 / CA membrane prepared in Example 3 was selected as the photoelectrocatalytic material in subsequent experiments.

[0088] Experimental Example 3: Performance Evaluation of Composite Photoelectrocatalytic Materials for Removing Chlorella

[0089] 1. Test method:

[0090] The experiment is designed with the following treatment:

[0091] Photocatalysis: The composite photocatalytic material prepared in Example 3 was used for the photocatalytic removal of Chlorella. The photocatalytic process was carried out in a photochemical reactor. 6 × 10⁶ μL of [material name missing] was added to the reactor. 6 100 mL of Chlorella cells / mL, FeCo₂O₄ / g-C₃N₄ / CA₄ 5% membrane (d = 3 cm), effective electrode area 2 cm × 5 cm graphite plate, 0.1 M NaCl as electrolyte solution, current density 2.0 mA / cm². 2 A 350W xenon lamp was used as the light source, and the reaction time was 180 min. 4 mL of algal solution was taken at fixed intervals, and the algae removal rate was analyzed using a UV-Vis spectrophotometer.

[0092] Individual light: Add 6×10 to the reactor 6 100 mL of Chlorella cells / mL was used as the light source, and a 350W xenon lamp was used to provide the light source. The reaction time was 180 min. 4 mL of algal solution was taken at fixed intervals, and the algal removal rate was analyzed using a UV-Vis spectrophotometer.

[0093] Photocatalysis: Add 6×10 to the reactor 6 100 mL of Chlorella cells / mL was used in a FeCo2O4 / g-C3N4 / CA-5% membrane (d = 3 cm). A 350W xenon lamp was used as the light source, and the reaction time was 180 min. 4 mL of algal solution was taken at fixed intervals, and the algal removal rate was analyzed using a UV-Vis spectrophotometer.

[0094] Electrocatalysis: Add 6×10 to the reactor 6100 mL of Chlorella cells / mL, FeCo₂O₄ / g-C₃N₄ / CA₄ 5% membrane (d = 3 cm), effective electrode area 2 cm × 5 cm graphite plate, 0.1 M NaCl as electrolyte solution, current density 2.0 mA / cm². 2 The reaction time was 180 min, and 4 mL of algal solution was taken at fixed intervals. The algae removal rate was analyzed using a UV-Vis spectrophotometer.

[0095] The formula for calculating the removal rate of each treatment is the same as that for Experimental Example 2.

[0096] 2. Test Results:

[0097] The results are as follows Figure 4 As shown, after 180 min of degradation reaction, the photoelectrocatalysis achieved a removal rate of 93.7% for Chlorella. Furthermore, the photoelectrocatalytic rate constant is greater than the sum of the photocatalytic and electrocatalytic rates, proving that this photoelectrocatalytic material is suitable for the photoelectrocatalytic removal of Chlorella and exhibits a synergistic photoelectrocatalytic degradation effect. Moreover, chlorophyll a release and electro-oxidation occur simultaneously within 20–40 min. The generated free radicals attack the adsorbed algal cell surface, damaging the algal cells, causing chloroplast damage, and releasing a large amount of chlorophyll. The chlorophyll a concentration increases rapidly within a short period.

[0098] Experimental Example 4: Evaluation of the Reusability of Composite Photoelectrocatalytic Materials

[0099] Under the experimental conditions described in Example 3, the FeCo2O4 / g-C3N4 / CA membrane prepared in Example 3 was subjected to four photoelectrocatalytic removal experiments of Chlorella. After the photoelectrocatalytic experiments were completed, the graphite electrode and FeCo2O4 / g-C3N4 / CA-5% were rinsed three times with deionized water, dried in an oven at 60°C for 2 hours, and then the experiment was carried out again.

[0100] The results are as follows Figure 5 As shown in the figure, the XRD patterns of FeCo2O4 / g-C3N4 / CA-5% before and after four cycles are basically the same, with all characteristic peaks retained. Furthermore, no other impurity peaks were found in the XRD pattern after four cycles, indicating that the crystal structure of the photocatalyst remained unchanged after four cycles. Therefore, FeCo2O4 / g-C3N4 / CA exhibits ideal stability and shows good promise for practical applications.

[0101] Depend on Figure 6 It can be seen that the removal rates of chlorophyll a in the four cycles were 93.7%, 93.4%, 92.55%, and 93.0%, respectively. The photoelectrocatalytic algae removal effect decreased slightly, but still reached over 90%, indicating that the material has good recyclability.

[0102] Experimental Example 5: Effects of Composite Photocatalytic Materials on Algal Cell Morphology

[0103] Using the experimental conditions described in Example 2, experiments were conducted on Chlorella using the FeCo2O4 / g-C3N4 / CA membrane prepared in Example 3, demonstrating the effect of photoelectrocatalysis on algal cell morphology.

[0104] The results are as follows Figure 7 As shown, at 90 minutes, the algal cells in the photoelectrocatalysis experimental group exhibited shrinkage and leakage of intracellular organic matter. This indicates that after the algal cells were attacked, the permeability of the cell membrane changed, leading to the damage and death of some algal cells. As the experiment progressed to 180 minutes, it was observed that almost all algal cells were damaged, and even the undamaged algal cells showed signs of shrinkage.

[0105] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. The application of composite photoelectrocatalytic materials in the removal of algae from water, characterized in that, The composite photoelectrocatalytic material is prepared by the following method: (1) Add FeCo2O4 to NaOH solution to obtain the first solution; add g-C3N4 to deionized water and stir evenly to obtain the second solution; mix the first solution and the second solution evenly and prepare FeCo2O4 / g-C3N4 by hydrothermal reaction; (2) Dissolve cellulose acetate in acetone to form a sol; add FeCo2O4 / g-C3N4 prepared in step (1) to the sol, mix with ultrasonication, pour into a petri dish, let stand to evaporate, and prepare the composite photoelectrocatalytic material. In step (1), the amount of FeCo2O4 added is 1%-15% of the mass of g-C3N4; In step (2), the ratio of cellulose acetate to FeCo2O4 / g-C3N4 added is 5:1-1:

1.

2. The application according to claim 1, characterized in that, The algae mentioned are green algae.

3. The application according to claim 2, characterized in that, The green algae mentioned is Chlorella vulgaris.

4. A photoelectrocatalytic system for controlling algal blooms, characterized in that, include: The composite photoelectrocatalytic material, graphite plate electrode, and electrolyte solution as described in claim 1.

5. The photoelectrocatalytic system according to claim 4, characterized in that, The electrolyte solution is 0.1M NaCl.

6. A method for removing algae from water using the photoelectrocatalytic system according to claim 4 or 5, characterized in that, Includes the following steps: The composite photocatalytic material of claim 1 is added to the water to be treated. A photocatalytic system is formed using a graphite plate as the electrode and 0.1 M NaCl as the electrolyte. Under light source irradiation conditions, by applying 2.0 mA / cm²... 2 Current density is used to remove algae from water.

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