Preparation method of iron-cerium modified porous biochar membrane and application of iron-cerium modified porous biochar membrane in adsorption and recovery of phosphate in water body

Abstract

The invention discloses a preparation method of an iron-cerium modified porous biochar membrane and application of the iron-cerium modified porous biochar membrane to adsorption and recovery of phosphate in a water body, and relates to the technical field of biochar membrane preparation. The method comprises the following steps: adding porous charcoal, cerium nitrate hexahydrate, ferric nitrate nonahydrate and ascorbic acid into distilled water, and oscillating under a water bath condition to obtain a mixed solution; adding a NaOH solution, oscillating under a water bath condition, filtering and then drying to obtain iron-cerium modified porous biochar; the iron-cerium modified porous biochar and a triton X-100 solution are mixed, a suspension is formed through ultrasonic treatment, then filtering and drying are conducted, the iron-cerium modified porous biochar film is obtained, and the iron-cerium modified porous biochar film is used for adsorbing and recycling phosphate in a water body. The invention can obtain the preparation method of the iron-cerium modified porous biochar film and the application of the iron-cerium modified porous biochar film in adsorption and recovery of phosphate in a water body.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biochar membrane preparation, and particularly relates to a preparation method of iron-cerium modified porous biochar membrane and application of the iron-cerium modified porous biochar membrane in adsorption and recovery of phosphate in water. BACKGROUND

[0002] With the continuous development of urbanization and industry and agriculture, a large amount of wastewater containing phosphorus elements is continuously discharged into natural water bodies, which will inevitably lead to water eutrophication over a long period of time. Eutrophic water bodies will cause a large number of algae to reproduce and the oxygen content of the water body to decrease, ultimately destroying the structure of the water body and affecting the ecological balance of the water body, posing a serious threat to drinking water supply and the health of residents. At the same time, phosphorus, as an essential nutrient element for the growth and development of plants, is one of the core fertilizer components in agricultural production, and the global phosphorus ore resources are facing the pressure of exhaustion, which is a non-renewable strategic resource. Therefore, removing and recovering phosphorus from phosphorus-containing contaminated water bodies not only is a key measure to curb water eutrophication and ensure water environment safety, but also can realize the recycling of phosphorus resources and provide a sustainable source of fertilizer for agricultural production, which has important practical significance and strategic value for efficient synergy of water body treatment and phosphorus resource utilization.

[0003] At present, the methods for removing phosphate in water bodies mainly include chemical precipitation, biological method, membrane separation method and adsorption method. Among them, the adsorption method has become one of the most widely used water phosphorus treatment methods due to its simple operation, low energy consumption, high adsorption efficiency and other characteristics. Biochar is a carbonaceous material prepared by pyrolysis or gasification of biomass under low oxygen or inert conditions, which has a porous structure and abundant surface functional groups (hydroxyl or carboxyl groups), and is a high-efficiency adsorbent. However, there are obvious limitations in the practical application of biochar. Generally, the apparent charge on the surface of the biochar is negative, which limits its binding affinity to anions such as phosphate, resulting in poor adsorption performance. In addition, the original biochar has fewer pores and less specific surface area, and the effective functional group loading is not high, which makes it difficult to efficiently combine with phosphate in water. Moreover, the powder-like adsorbent is difficult to separate in water, which limits its wide application in water phosphorus adsorption.

[0004] In order to solve the above problems, the commonly used modification methods at present include acid-base modification, element doping and metal loading. However, according to the previous literature reports, the commonly used cerium-based adsorbents will inevitably be oxidized from Ce(III) to Ce(IV) in the synthesis process, which weakens the adsorption of cerium-based adsorbents to phosphate. In view of the above problems, it is urgent to find a modification method which is simple in preparation method and can solve the above defects of biochar. SUMMARY

[0005] The present application aims to solve the above technical problems and provides a preparation method of iron-cerium modified porous biochar membrane and application of the iron-cerium modified porous biochar membrane in adsorption and recovery of phosphate in water.

[0006] A preparation method of an iron-cerium modified porous biochar film is carried out in the following steps:

[0007] Step S1, preparing a porous biochar:

[0008] The straw powder and KHCO3 are mixed, heated to 600-800 DEG C under a nitrogen atmosphere, and kept at a temperature of 600-800 DEG C for 110-130 min; after the heat preservation is completed, washing to neutral, and then drying, to obtain a porous biochar;

[0009] Step S2, preparing an iron-cerium modified porous biochar:

[0010] The porous biochar obtained in step S1, Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid are added to distilled water, and oscillated under water bath conditions to obtain a mixed solution; then NaOH solution is added, oscillated under water bath conditions, filtered and dried to obtain an iron-cerium modified porous biochar;

[0011] Step S3, preparing an iron-cerium modified porous biochar film:

[0012] The iron-cerium modified porous biochar obtained in step S2 and a Triton X-100 solution are mixed, ultrasonically formed into a suspension, and then filtered and dried to obtain an iron-cerium modified porous biochar film;

[0013] The ratio of the mass of the iron-cerium modified porous biochar to the volume of Triton X-100 in the Triton X-100 solution and the volume of distilled water is 200 mg: (1.5-2) mL: 150 mL, 300 mg: (1.5-2) mL: 150 mL, 400 mg: (1.5-2) mL: 150 mL or 500 mg: (1.5-2) mL: 150 mL.

[0014] An application of an iron-cerium modified porous biochar film, the iron-cerium modified porous biochar film is used for adsorbing and recovering phosphate in water.

[0015] The beneficial effects of the present application are:

[0016] (1) The present application reasonably regulates the ratio of iron and cerium, utilizes the different phosphate binding strengths of iron and cerium, highlights the strong affinity of cerium for phosphate, and increases the adsorption selectivity of the material for phosphate; utilizes the different isoelectric points of iron and cerium, so that the material still has effectiveness in a wide pH range, and ascorbic acid is added during synthesis, the protective effect of ascorbic acid is utilized to effectively inhibit the oxidation of trivalent cerium to tetravalent cerium, thereby maintaining its high adsorption activity for phosphate; at the same time, the developed pore structure of the porous biochar significantly improves the loading efficiency of cerium. In addition, the introduction of iron not only endows the material with magnetism, realizes convenient recovery after use; and iron and cerium can form a composite metal hydroxide, which is uniformly loaded on the surface and pores of the biochar, improving the pore structure of the material and further enhancing the overall stability of the material. Finally, by preparing the carbon powder into a carbon film structure, the separation and recovery efficiency of the material is greatly improved, realizing the sustained and efficient adsorption and resource recovery of phosphate.

[0017] (2) The present application provides a phosphate adsorption material applicable to water bodies, and the iron-cerium modified porous biochar film has almost no effect on the adsorption of phosphate in the range of 25-45 DEG C, and has wide adaptability to pH, which can realize efficient adsorption of phosphate in water bodies, and promote the development and application of phosphate adsorbents in water bodies.

[0018] The present application can obtain a preparation method of an iron-cerium modified porous biochar film and its application in adsorbing and recovering phosphate in water bodies. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The scanning electron microscope image of the iron-cerium modified porous biochar film in Example 1 is shown;

[0020] Figure 2 The element mapping image of the iron-cerium modified porous biochar film in Example 1 is shown;

[0021] Figure 3 The scanning electron microscope image of the iron-cerium modified porous biochar film in Example 1 is shown;

[0022] Figure 4 The element mapping image of the iron-cerium modified porous biochar film in Example 1 is shown;

[0023] Figure 5 The adsorption effect of the iron-cerium modified porous biochar film on phosphate in Examples 1-4 synthesized by using different amounts of Fe / Ce-PBC is shown;

[0024] Figure 6 The adsorption effect of the iron-cerium modified porous biochar film on phosphate in Example 1 under different pH conditions (pH=2, 3, 4, 5 or 6) is shown;

[0025] Figure 7 FIG. 1 shows the adsorption effect of the iron-cerium modified porous biochar membrane on phosphate at different temperatures (25℃, 35℃ or 45℃) in Example 1;

[0026] Figure 8 FIG. 2 shows the adsorption effect of the iron-cerium modified porous biochar membrane on phosphate at different times (0~24 h) in Example 1;

[0027] Figure 9 FIG. 3 shows the intraparticle diffusion model fitting results of the adsorption process of the iron-cerium modified porous biochar membrane on phosphate at different times (0~24 h) in Example 1. DETAILED DESCRIPTION

[0028] Specific embodiment one: a preparation method of the iron-cerium modified porous biochar membrane in the embodiment, which is carried out according to the following steps:

[0029] Step S1, preparing the porous biochar:

[0030] Mixing the straw powder and KHCO3, heating to 600~800℃ under nitrogen atmosphere, and keeping the temperature at 600~800℃ for 110~130 min; after the end of the heat preservation, washing to neutral, and then drying to obtain the porous biochar;

[0031] Step S2, preparing the iron-cerium modified porous biochar:

[0032] Adding the porous biochar obtained in step S1, Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid into distilled water, and oscillating under water bath conditions to obtain a mixed solution; then adding NaOH solution, oscillating under water bath conditions, filtering, and then drying to obtain the iron-cerium modified porous biochar;

[0033] Step S3, preparing the iron-cerium modified porous biochar membrane:

[0034] Mixing the iron-cerium modified porous biochar obtained in step S2 and the Triton X-100 solution, forming a suspension by ultrasonic, and then filtering and drying to obtain the iron-cerium modified porous biochar membrane;

[0035] The ratio of the mass of the iron-cerium modified porous biochar to the volume of Triton X-100 in the Triton X-100 solution and the volume of distilled water is 200 mg: (1.5~2) mL: 150 mL, 300 mg: (1.5~2) mL: 150 mL, 400 mg: (1.5~2) mL: 150 mL or 500 mg: (1.5~2) mL: 150 mL.

[0036] Specific implementation two: the difference between this embodiment and specific implementation one is that the mass ratio of straw powder to KHCO3 in step S1 is 1: (0.8-1).

[0037] The other steps are the same as specific implementation one.

[0038] Specific implementation three: the difference between this embodiment and specific implementation one or two is that the temperature is raised to 600-800℃ at a temperature rise rate of 5-10℃ / min in step S1.

[0039] The other steps are the same as specific implementation one or two.

[0040] Specific implementation four: the difference between this embodiment and one of specific implementation one to three is that the mass ratio of porous biochar to Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid in step S2 is (9-11):(19-21):(4-6):(15-17).

[0041] The other steps are the same as specific implementation one to three.

[0042] Specific implementation five: the difference between this embodiment and one of specific implementation one to four is that the ratio of the mass of porous biochar to the volume of distilled water in step S2 is (0.9-1.1)g:(145-155)mL.

[0043] The other steps are the same as specific implementation one to four.

[0044] Specific implementation six: the difference between this embodiment and one of specific implementation one to five is that the porous biochar, Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid are added to distilled water in step S2, and oscillated at 50-55℃ water bath for 11-12h; NaOH solution is added and oscillated at 25-30℃ water bath for 30-40min.

[0045] The other steps are the same as specific implementation one to five.

[0046] Specific implementation seven: the difference between this embodiment and one of specific implementation one to six is that the volume ratio of NaOH solution to mixed solution in step S2 is 1:(3-4), and the concentration of NaOH solution is 0.4-0.55M.

[0047] The other steps are the same as specific implementation one to six.

[0048] Embodiment eight: the difference between this embodiment and one of embodiments one to seven is that the ratio of the mass of the iron-cerium modified porous biochar to the volume of Triton X-100 in the Triton X-100 solution and the volume of distilled water is 300 mg: 1.5 mL: 150 mL.

[0049] The other steps are the same as those in embodiments one to seven.

[0050] Embodiment nine: the difference between this embodiment and one of embodiments one to eight is that the ultrasonic time in step S3 is 30-40 min; and the filtration uses a nitrocellulose membrane, and after filtration, the nitrocellulose membrane is removed using acetone.

[0051] The other steps are the same as those in embodiments one to eight.

[0052] Embodiment ten: an application of the iron-cerium modified porous biochar film, the iron-cerium modified porous biochar film is used for adsorbing and recovering phosphate in water.

[0053] The beneficial effects of the present application are verified by the following examples:

[0054] Example 1: a preparation method of an iron-cerium modified porous biochar film, which is carried out according to the following steps:

[0055] Step S1, preparation of porous biochar:

[0056] The straw powder and KHCO3 are mixed, heated to 700℃ at a heating rate of 10℃ / min under a nitrogen atmosphere, and kept at 700℃ for 120 min, the mass ratio of the straw powder to KHCO3 is 1:1; after the heat preservation is completed, the obtained sample is washed to neutral, and then dried to obtain the porous biochar (PBC);

[0057] Step S2, preparation of iron-cerium modified porous biochar:

[0058] The porous biochar, Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid are added to distilled water, and oscillated at 50℃ water bath for 12 h to obtain a mixed solution, the mass ratio of the porous biochar to Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid is 10:20:5:16, and the ratio of the mass of the porous biochar to the volume of distilled water is 1 g:150 mL; then 0.5 M NaOH solution is added, oscillated at 25℃ water bath for 40 min, and then dried after filtration to obtain the iron-cerium modified porous biochar (Fe / Ce-PBC);

[0059] The volume ratio of the NaOH solution to the mixed solution is 1:4.

[0060] Step S3: Preparation of iron-cerium modified porous biochar membrane:

[0061] 300 mg of iron / cerium modified porous biochar was mixed with Triton X-100 solution (1.5 mL Triton X-100, 150 mL distilled water), and sonicated for 40 min to form a suspension. The suspension was then filtered through a nitrocellulose membrane, and the nitrocellulose membrane was removed with acetone after filtration. Finally, the membrane was dried to obtain an iron / cerium modified porous biochar membrane (Fe / Ce-PBCF).

[0062] Example 2: In this example, the amount of Fe / Ce-PBC added was 200 mg. All other experimental conditions were the same as in Example 1.

[0063] Example 3: In this example, the amount of Fe / Ce-PBC added was 400 mg. All other experimental conditions were the same as in Example 1.

[0064] Example 4: In this example, the amount of Fe / Ce-PBC added was 500 mg. All other experimental conditions were the same as in Example 1.

[0065] The iron-cerium modified porous biochar membrane material prepared using the above examples was subjected to material dosage experiments and water phosphate adsorption experiments under different conditions. The specific conclusions are as follows:

[0066] Figure 1 This shows a scanning electron microscope image of the iron-cerium modified porous biochar membrane in Example 1; as shown. Figure 1 As shown, the iron-cerium modified porous biochar membrane has a distinct pore structure and a particulate structure, which is supported by iron and cerium.

[0067] Figure 2 This shows the elemental mapping diagram of the iron-cerium modified porous biochar membrane in Example 1; as shown. Figure 2 As shown, iron and cerium are uniformly distributed on the material surface, proving the successful loading of iron and cerium.

[0068] Figure 3 This shows a scanning electron microscope image of the iron-cerium modified porous biochar membrane after phosphate adsorption in Example 1; as shown. Figure 3 As shown, the surface of the biochar membrane after phosphate adsorption still has a porous structure and a large number of dendritic crystals appear, proving that phosphate is adsorbed onto the material surface.

[0069] Figure 4 This shows the elemental mapping diagram of the iron-cerium modified porous biochar membrane after phosphate adsorption in Example 1; as shown. Figure 4 As shown, after phosphate adsorption, the material surface is uniformly covered with phosphorus, proving that the phosphate was successfully adsorbed.

[0070] 2. Effect of different Fe / Ce-PBC dosages:

[0071] The adsorption process was as follows: 0.05 g of iron-cerium modified porous biochar membranes synthesized with different Fe / Ce-PBC dosages were weighed using a balance and added to a 150 mL Erlenmeyer flask. Then, 100 mL of phosphate solution was added to the Erlenmeyer flask, and the initial pH of the solution was adjusted to 3.0 with 0.1 M HCl. After shaking at 200 rpm and 25 °C for 24 h, the concentration of phosphate in the solution was measured, and the adsorption efficiency of the adsorption material was calculated.

[0072] Figure 5 The graphs show the adsorption effects of phosphate on iron-cerium modified porous biochar membranes synthesized with different Fe / Ce-PBC dosages in Examples 1-4; for example... Figure 5 As shown, the iron-cerium modified porous biochar membranes synthesized using 200~400 mg all had a phosphate adsorption capacity of 60 mg / g, with the best effect observed at a dosage of 300 mg. However, when the dosage of Fe / Ce-PBC was 500 mg, the adsorption effect was much lower than that of other treatment groups. This is because excessive Fe / Ce-PBC leads to an increase in membrane thickness, which reduces the specific surface area and porosity of the material, thereby reducing the phosphate mass transfer efficiency and resulting in a lower adsorption capacity than other treatment groups. Therefore, 300 mg of Fe / Ce-PBC was selected as the optimal dosage for synthesizing iron-cerium modified porous biochar membranes.

[0073] 3. The effect of different pH values:

[0074] The adsorption process was as follows: 0.05 g of iron-cerium modified porous biochar membrane was weighed using a balance and added to a 150 mL Erlenmeyer flask. Then, 100 mL of phosphate solution was added to the Erlenmeyer flask. The initial pH of the solution was adjusted to 2, 3, 4, 5 and 6 with 0.1 M HCl. After shaking at 200 rpm for 24 h in a 25℃ water bath, the concentration of phosphate in the solution was measured, and the adsorption efficiency of the adsorption material was calculated.

[0075] Figure 6 This diagram illustrates the phosphate adsorption effect of the iron-cerium modified porous biochar membrane in Example 1 under different pH conditions (pH=2, 3, 4, 5, or 6); Figure 6 As shown, the material exhibits the highest adsorption capacity for phosphate at pH=2; while at pH>2, the adsorption capacity for phosphate gradually decreases, but the adsorption efficiency remains above 60%, indicating that the material has good tolerance and adsorption effect in acidic and slightly acidic environments.

[0076] 4. The effect of different temperatures:

[0077] The adsorption process is: using a balance to take 0.05 g of iron and cerium modified porous biochar membrane, adding it into a 150 mL conical flask, then adding 100 mL of phosphate solution into the conical flask, adjusting the initial pH value of the solution to 3.0 with 0.1 M HCl, and oscillating at 200 rpm in a 25℃ water bath for 24 h, then measuring the concentration of phosphate in the solution, and calculating the adsorption efficiency of the adsorption material.

[0078] Figure 7 The figure shows the adsorption effect of the iron and cerium modified porous biochar membrane in Example 1 on phosphate at different temperatures (25℃, 35℃ or 45℃); as shown in Figure 7 , under three different temperature conditions, with the increase of the initial concentration, the adsorption capacity of the material on phosphate also increases, and the adsorption capacity of the material increases with the increase of the temperature, indicating that the adsorption process of the material on phosphate is an endothermic process. In addition, the R 2 of Langmuir model is 0.98, the R 2 of Freundlich model is 0.99, and the R 2 of Sips model is 0.97; it can be seen that the fitting effect of Freundlich model is better, indicating that the adsorption of iron and cerium modified porous biochar membrane on phosphate is a heterogeneous multilayer adsorption.

[0079] 5. Effect of adsorption time:

[0080] The adsorption process is: using a balance to take 0.05 g of iron and cerium modified porous biochar membrane, adding it into a 150 mL conical flask, then adding 100 mL of phosphate solution into the conical flask, adjusting the initial pH value of the solution to 3.0 with 0.1 M HCl, and oscillating at 200 rpm in a 25℃ water bath for 24 h, during which samples were taken, the concentration of phosphate in the solution was measured, and the adsorption efficiency of the adsorption material was calculated.

[0081] Figure 8 The figure shows the adsorption effect of the iron and cerium modified porous biochar membrane in Example 1 on phosphate at different times (0~24 h); points were taken at 5 min, 15 min, 30 min, 60 min, 2 h, 4 h, 8 h, 12 h and 24 h, as shown in Figure 8 , the adsorption of the material on phosphate increases rapidly within the initial 4 h, and the adsorption effect gradually stabilizes after 8 h, and finally gradually tends to be balanced. The results of the adsorption of phosphate by the iron and cerium modified porous biochar membrane were fitted using three kinds of kinetic models, namely pseudo-first-order, pseudo-second-order and Avrami fractional order model, among which the R 2 of pseudo-first-order kinetic model is 0.93, the R 2The R-value of the Avrami fractional model is 0.97. 2 The value is 0.99; due to the R-value of the Avrami fractional model... 2 The maximum value of the kinetic model allows for a good fit of the phosphate adsorption process of iron-cerium modified porous biochar membranes, indicating that the adsorption process is not a simple physical or chemical adsorption, but a complex and multi-stage adsorption process involving multiple mechanisms. Furthermore, the R0 of the pseudo-second-order kinetic model is [value missing]. 2 The results are greater than those of a pseudo-first-order kinetic model, indicating that chemisorption plays a dominant role.

[0082] Figure 9 This figure shows the fitting results of the intraparticle diffusion model for the phosphate adsorption process of the iron-cerium modified porous biochar membrane in Example 1 at different time points (0~24 h); as shown. Figure 9 As shown, both fitted curves exhibit intercepts, indicating that intraparticle diffusion—the diffusion of phosphate from the carbon film surface to its internal pores—is one of the main controlling steps of the adsorption rate, but not the only one. This further suggests that the adsorption process is controlled by multiple consecutive steps. Furthermore, the intercept of the first straight line is less than zero because the carbon film surface has a certain degree of hydrophobicity, indicating an initial surface wetting stage during phosphate adsorption. Therefore, the phosphate adsorption process of iron-cerium modified porous biochar membranes can be roughly divided into three stages: surface wetting, external surface adsorption, and intraparticle diffusion.

Claims

1. A method for preparing an iron-cerium modified porous biochar membrane, characterized in that, The preparation method is carried out according to the following steps: Step S1: Preparation of porous biochar: Straw powder and KHCO3 were mixed and heated to 600-800℃ under a nitrogen atmosphere, and kept at 600-800℃ for 110-130 min. After the holding time, the mixture was washed until neutral and then dried to obtain porous biochar. Step S2: Preparation of iron-cerium modified porous biochar: The porous biochar obtained in step S1, Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid were added to distilled water and shaken under water bath conditions to obtain a mixed solution; then NaOH solution was added, shaken under water bath conditions, filtered and dried to obtain iron-cerium modified porous biochar. Step S3: Preparation of iron-cerium modified porous biochar membrane: The iron-cerium modified porous biochar obtained in step S2 is mixed with Triton X-100 solution, and then a suspension is formed by ultrasonication. After filtration and drying, an iron-cerium modified porous biochar membrane is obtained. The mass ratio of the iron-cerium modified porous biochar to the volume of Triton X-100 and the volume of distilled water in the Triton X-100 solution is 200 mg: (1.5~2) mL: 150 mL, 300 mg: (1.5~2) mL: 150 mL, 400 mg: (1.5~2) mL: 150 mL, or 500 mg: (1.5~2) mL: 150 mL.

2. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, The mass ratio of straw powder to KHCO3 in step S1 is 1:(0.8~1).

3. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, In step S1, the temperature is increased to 600-800℃ at a heating rate of 5-10℃ / min.

4. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, The mass ratio of porous biochar to Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid in step S2 is (9~11):(19~21):(4~6):(15~17).

5. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, The ratio of the mass of porous biochar to the volume of distilled water in step S2 is (0.9~1.1) g : (145~155) mL.

6. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, In step S2, porous biochar, Ce(NO3)3·6H2O, Fe(NO3)3·9H2O and ascorbic acid are added to distilled water and shaken in a water bath at 50~55℃ for 11~12 h; then NaOH solution is added and shaken in a water bath at 25~30℃ for 30~40 min.

7. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, The volume ratio of NaOH solution to mixed solution in step S2 is 1:(3~4), and the concentration of NaOH solution is 0.4~0.55 M.

8. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, The mass ratio of the iron-cerium modified porous biochar to the volume of Triton X-100 and the volume of distilled water in the Triton X-100 solution is 300 mg: 1.5 mL: 150 mL.

9. The method for preparing an iron-cerium modified porous biochar membrane according to claim 1, characterized in that, In step S3, the ultrasonic time is 30-40 min; filtration is performed using a nitrocellulose membrane, and acetone is used to remove the nitrocellulose membrane after filtration.

10. The application of an iron-cerium modified porous biochar membrane prepared by the method according to any one of claims 1-9, characterized in that, The iron-cerium modified porous biochar membrane is used to adsorb and recover phosphates in water.

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