Preparation method and application of cuprous oxide loaded phosphoric acid modified biochar composite adsorption material

Abstract

The present application belongs to the field of environmental engineering and water pollution control technology, and particularly relates to a preparation method and application of a cuprous oxide loaded phosphoric acid modified biochar composite adsorption material. The method comprises soaking corn cob powder in a phosphoric acid solution to obtain a mixed precursor; the mixed precursor is calcined and activated at high temperature under inert gas protection to obtain phosphoric acid modified biochar; the phosphoric acid modified biochar is dispersed in an aqueous solution containing soluble copper salt, and is fully adsorbed and mixed; the system is adjusted to be weakly alkaline, and then a reducing agent is added under heating to generate cuprous oxide nanoparticles; after the reaction is completed, the solid-liquid mixture is separated, and the composite adsorption material is obtained after post-treatment. The present application realizes efficient removal of weakly polar phenolic pollutants in wastewater; the preparation method is simple to operate and has low operating cost; the present application has excellent pre-settling properties, significantly optimizes the solid-liquid separation process in practical application, and has good popularization and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering and water pollution control technology, specifically relating to a modified biochar composite material for adsorbing phenolic pollutants in water and its preparation method. Background Technology

[0002] Phenolic compounds (such as phenol) are a class of typical highly toxic, teratogenic, and recalcitrant organic pollutants, posing a serious threat to aquatic ecosystems and human health. Among existing wastewater treatment technologies, adsorption has become the most promising core technology in engineering applications due to its advantages such as simple operation, low cost, and no byproducts. In recent years, biochar prepared from agricultural waste (such as corn cobs) has become an ideal carbon substrate material for treating phenolic pollutants due to its wide availability, environmental friendliness, and well-developed porosity.

[0003] To improve the adsorption performance of biochar, acid-base modification or loading with metal oxides is often used to increase surface active sites. However, traditional modification processes face two major technical bottlenecks: First, the conventional "carbonization followed by activation" secondary high-temperature pyrolysis process is cumbersome, energy-intensive, and accompanied by severe equipment corrosion and carbon loss, making it difficult to achieve low-cost green production; second, existing modified materials have a single adsorption mechanism and have failed to form an effective multi-component synergistic effect, resulting in a significant upper limit to their adsorption capacity for phenol.

[0004] Therefore, it is of great significance to rationally design the pore structure and surface chemical properties of biochar and develop a green, mild, and high-adsorption-capacity composite adsorbent. Summary of the Invention

[0005] To address the technical problems of the existing technologies, such as demanding preparation processes and limited adsorption mechanisms, the present invention aims to provide a cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material, its preparation method, and its application, thereby achieving simple synthesis of the composite adsorbent material and efficient removal of phenol.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material, comprising the following steps: S1. Wash, dry and crush corn cobs to obtain corn cob powder; then soak the corn cob powder in a phosphoric acid solution with a mass fraction of 30%~85% and fully impregnate to obtain a mixed precursor; S2. The mixed precursor is activated by high-temperature calcination under inert gas protection. After cooling, the solid product is washed and dried to obtain phosphoric acid modified biochar. S3. Disperse the phosphoric acid modified biochar in an aqueous solution containing soluble copper salt to allow it to be fully adsorbed and mixed. S4. Slowly add alkaline solution to the mixed system to adjust the system to be weakly alkaline. Then add a reducing agent under heating conditions to reduce the copper precursor in situ on the surface of biochar and in the micropores to generate cuprous oxide nanoparticles. S5. After the reaction is complete, the solid-liquid mixture is separated. The solid product is then washed alternately and dried under vacuum to obtain the composite adsorbent material.

[0007] Optionally, the washing conditions are repeated washing with ultrapure water to remove surface impurities; the drying conditions are drying at 60-70℃ for 10-24 hours.

[0008] Optionally, the corn cob powder has a particle size of 80-120 mesh.

[0009] Furthermore, the phosphoric acid solution has a mass fraction of 85%.

[0010] Optionally, the mass ratio of corn cob to phosphoric acid solution for impregnation is 1:1 to 1:3.

[0011] Furthermore, the mass ratio of the corn cob to the phosphoric acid solution used for impregnation is 1:2.

[0012] Optionally, the impregnation conditions are: standing at room temperature for 12-24 hours.

[0013] Optionally, the inert gas is nitrogen or argon, and the gas flow rate is 30-80 mL / min.

[0014] Optionally, the conditions for high-temperature calcination activation are: heating to 400-600℃ at a heating rate of 2-10℃ / min and maintaining the temperature at a constant temperature for 60-180min.

[0015] Furthermore, the conditions for high-temperature calcination activation are: heating to 600°C at a heating rate of 5°C / min and maintaining the temperature at a constant temperature for 180min.

[0016] Optionally, the soluble copper salt is at least one of copper sulfate, copper nitrate, or copper chloride.

[0017] Furthermore, the copper salt is copper sulfate pentahydrate.

[0018] Optionally, the mass ratio of the phosphoric acid modified biochar to copper salt (CuSO4·5H2O) is 10:1-10:3.

[0019] Furthermore, the mass ratio of the phosphoric acid-modified biochar to the copper salt is 5:1.

[0020] Optionally, the alkaline solution is a 0.01 mol / L sodium hydroxide solution, and the pH of the system is adjusted to 9-11.

[0021] Furthermore, the pH value of the system is preferably adjusted to 10.

[0022] Optionally, the reducing agent is at least one of glucose or ascorbic acid.

[0023] Furthermore, the reducing agent is glucose, and the molar ratio of glucose to copper salt is 1:2.

[0024] Optionally, the heating conditions are a constant temperature reaction at 50-70°C for 1-2 hours.

[0025] Furthermore, the preferred heating condition is a constant temperature reaction at 60°C for 1.5 hours.

[0026] This invention discloses a cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent obtained by the above preparation method.

[0027] This invention also discloses the application of the above-mentioned composite adsorbent material in the treatment of phenol-containing wastewater.

[0028] Optionally, the phenolic contaminant is phenol.

[0029] Compared with the prior art, the present invention has the following advantages and significant technical effects:

[0030] (1) The cuprous oxide-supported phosphoric acid-modified biochar system constructed in this invention achieves efficient removal of weakly polar phenolic pollutants in wastewater. Its comprehensive adsorption capacity and removal efficiency are significantly better than those of single carbon-based adsorbents or conventional metal oxides.

[0031] (2) The composite material of the present invention has multiple complementary pollutant adsorption mechanisms: phosphoric acid modified biochar effectively enriches pollutants through pore interception, hydrogen bonding and π-π interaction; cuprous oxide nanoparticles grown in situ in confined space act as Lewis acid sites to generate strong chemical coordination with phenol, and the two work together to significantly improve the adsorption efficiency and stability of the system.

[0032] (3) This invention uses corn cobs, agricultural waste, as raw material to prepare biochar, realizing the recycling of resources; at the same time, it adopts a mild one-step phosphoric acid activation method to replace the highly corrosive strong alkali activation, making the process safe and environmentally friendly, in line with the concept of green circular economy, and having both environmental and economic benefits.

[0033] (4) The preparation method of the present invention is simple to operate and has low operating cost; and the composite material has excellent pre-sedimentation characteristics due to the loading of metal oxides, which significantly optimizes the solid-liquid separation process in practical applications and has good prospects for promotion and application. Attached Figure Description

[0034] Figure 1 This is a microstructure and surface C, P, O and Cu element distribution diagram of the 2.7% Cu2O / PBC composite material prepared in Example 9 of the present invention.

[0035] Figure 2 This is a comparison chart of the equilibrium adsorption capacity of the adsorbent materials prepared in Examples 7 and 9 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be described in detail below with reference to specific embodiments. It should be particularly noted that the following embodiments are only intended to help those skilled in the art to better understand and implement the present invention, and should not be regarded as a limitation on the scope of protection of the present invention.

[0037] Unless otherwise specified, the experimental methods described in the embodiments of this invention are all conventional methods; unless otherwise specified, the reagents, raw materials and instruments can be obtained from commercial channels.

[0038] In some specific embodiments, the preparation method of the cuprous oxide-supported phosphoric acid-modified biochar composite material of the present invention includes the following steps:

[0039] Pretreatment of corn cobs: Waste corn cobs are washed with ultrapure water and dried at 60°C to constant weight; then they are crushed and passed through a 100-mesh sieve, and the sieve material is collected to obtain corn cob powder for later use.

[0040] Phosphoric acid impregnation and cross-linking pre-reconstruction: The corn cob powder is impregnated in an 85% H3PO4 solution, stirred evenly, and then left to stand at room temperature for 12-24 hours to allow the corn cob powder to fully contact the activator.

[0041] In some specific embodiments, the impregnation mass ratio of corn cob powder to 85% phosphoric acid solution is 1:1 to 1:3. Unlike the cumbersome two-step process requiring "first carbonization, then secondary high-temperature activation" with traditional strong alkalis (such as KOH) as activators, this invention utilizes the unique properties of phosphoric acid to achieve a one-step reconstruction of corn cob biomass carbonization, directional pore formation, and surface functionalization. At this stage, the appropriate impregnation ratio ensures that phosphoric acid molecules deeply penetrate the interior of lignocellulose, pre-constructing a polymer network rich in phosphate ester bonds (COP), laying the foundation for the hierarchical pore directional expansion in the subsequent high-temperature pyrolysis stage.

[0042] Preparation of phosphoric acid modified biochar: The above impregnated precursor was transferred to a tube furnace and calcined at medium and high temperature under an inert atmosphere. After washing and drying, phosphoric acid modified porous biochar (PBC) was obtained.

[0043] In some specific embodiments, the calcination temperature is 400-600℃, and the holding time is 60-180 min. Suitable calcination temperature and holding time are key parameters determining pore development and surface chemical properties. In the initial stage of pyrolysis, the previously constructed COP cross-linked network effectively prevents the skeleton from drastically shrinking and collapsing at high temperatures. As the pyrolysis temperature continues to rise, the strongly oxidizing P2O5 generated by the dehydration condensation of phosphoric acid initiates deep chemical etching of the carbon skeleton, not only promoting the development of hierarchical pores but also generating high-density phosphorus / oxygen-containing active sites such as P=O on the carbon surface, providing a favorable support for subsequent in-situ Cu2O loading.

[0044] Preparation of Cu 2+ Ionic solution: Copper salt is dissolved in ultrapure water to prepare Cu 2+ Ionic solutions.

[0045] In some specific embodiments, the soluble copper salt is preferably copper sulfate.

[0046] Modified biochar and Cu 2+ Mixing: Phosphoric acid-modified biochar was dispersed in ultrapure water, and a certain amount of copper salt solution was added to make Cu... 2+ It is uniformly adsorbed on the surface and in the pores of biochar.

[0047] In some specific embodiments, the mass ratio of the modified biochar to copper sulfate pentahydrate is controlled at 10:1-10:3. After mixing the system under the above conditions, the treatment process includes ultrasonic dispersion for 0.5 h, followed by continuous stirring at room temperature for 6 h.

[0048] Alkali precipitation treatment: Slowly add an alkaline regulator to the above mixed suspension to adjust the system to a weakly alkaline state, so that the Cu anchored in the channels... 2+ It is converted in situ into a copper hydroxide precursor.

[0049] In some specific embodiments, the alkaline regulator is a 0.01 mol / L sodium hydroxide solution, which, after being added dropwise, adjusts the pH of the system to 9-10.

[0050] In-situ reduction of cuprous oxide: The above system was placed in a heating device, and glucose reducing agent was introduced for a isothermal reaction. After the reaction was completed, the mixture was separated into solid and liquid components, washed, and dried to obtain a cuprous oxide-supported phosphoric acid-modified porous biochar composite material.

[0051] In some specific embodiments, the reducing agent is glucose, the molar ratio of glucose to copper sulfate is 1:2, the heating equipment is a constant temperature oil bath, the reaction temperature is 60°C, and the reaction time is 1.5h.

[0052] Glucose, as a mild reducing agent, will bind the pre-anchored Cu 2+Precise reduction to Cu2O effectively avoids over-reduction and excessive grain growth. The generated Cu2O nanoparticles, as the core chemically active component, possess a strong coordination and capture ability for pollutants such as phenol at their Lewis acid sites. This process integrates the chemical coordination of Cu2O, the physical retention by the hierarchical pores of biochar, and the hydrogen bonding of oxygen-containing functional groups. The synergistic effect of these three factors determines the excellent adsorption performance of the composite material.

[0053] This invention discloses a cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent obtained by the above preparation method.

[0054] The present invention also discloses the application of the above-mentioned composite adsorbent material in the treatment of phenol-containing wastewater.

[0055] In some specific embodiments, the phenolic contaminant is phenol, with an initial concentration of 50 mg / L.

[0056] The technical solution of the present invention will be further illustrated by the following embodiments.

[0057] Example 1

[0058] A method for preparing phosphoric acid modified biochar specifically includes the following steps: S1. Take 3g of dried corn cob powder into a beaker and add 4.5g of 85% phosphoric acid solution at a mass ratio of 1:1.5.

[0059] S2. Stir thoroughly to ensure even mixing, and let stand at room temperature for 18 hours for thorough impregnation.

[0060] S3. Transfer the impregnated precursor to a crucible and push it into a tube furnace. Heat it to 500°C at a heating rate of 5°C / min under a nitrogen atmosphere and hold it at that temperature for 180 min.

[0061] S4. After the tube furnace has cooled to room temperature, remove the carbonized product and grind it evenly in a ceramic mortar.

[0062] S5. First, wash with 0.1 mol / L NaOH solution to neutralize the residual acid, then repeatedly filter and wash with ultrapure water until the pH of the filtrate is neutral.

[0063] S6. Place the washed biochar in a vacuum drying oven and dry it to constant weight to obtain phosphoric acid activated modified biochar, labeled as PBC-500-180-1.5.

[0064] Example 2

[0065] A method for preparing phosphoric acid modified biochar is basically the same as that in Example 1, except that in S1, the mass ratio of corn cob powder to 85% phosphoric acid solution is adjusted to 1:2, and the final product is labeled as PBC-500-180-2.

[0066] Example 3

[0067] A method for preparing phosphoric acid modified biochar is basically the same as that in Example 1, except that in S1, the mass ratio of corn cob powder to 85% phosphoric acid solution is adjusted to 1:2.5; the final product is labeled as PBC-500-180-2.5.

[0068] Example 4

[0069] A method for preparing phosphoric acid modified biochar is basically the same as that in Example 2, except that in S3, the isothermal holding time of high-temperature calcination is adjusted to 60 min; the final product is labeled as PBC-500-60-2.

[0070] Example 5

[0071] A method for preparing phosphoric acid modified biochar is basically the same as that in Example 2, except that in S3, the isothermal holding time of high-temperature calcination is adjusted to 120 min; the final product is labeled as PBC-500-120-2.

[0072] Example 6

[0073] A method for preparing phosphoric acid modified biochar is basically the same as that in Example 2, except that in S3, the heating temperature for high-temperature calcination is adjusted to 400℃; the final product is labeled as PBC-400-180-2.

[0074] Example 7

[0075] A method for preparing phosphoric acid modified biochar is basically the same as that in Example 2, except that in S3, the heating temperature for high-temperature calcination is adjusted to 600℃; the final product is labeled as PBC-600-180-2.

[0076] Test Example 1 The specific surface area and pore structure of each sample were routinely determined using the nitrogen adsorption-desorption method (BET model).

[0077] A phenol solution with a concentration of 50 mg / L was prepared as simulated wastewater. 10 mg of each example and comparative material was weighed into a beaker, and 20 ml of simulated wastewater was added. The sealed beaker was placed in a constant temperature shaking incubator and shaken at 27°C and 150 r / min. After adsorption equilibrium was reached, 1 ml of the supernatant was extracted, filtered through a 0.22 μm filter membrane, and the absorbance at 270 nm was measured using a UV-Vis spectrophotometer. The equilibrium adsorption capacity of biochar for phenol (q) was calculated. e )

[0078] The performance data of the phosphoric acid modified biochar in the above embodiments are shown in Table 1: Table 1. Comparison of pore structure and preliminary adsorption performance of different phosphoric acid-modified porous biochars <![CDATA[Specific surface area (m 2 / g)]]> 954.68 1,146.58 986.88 964.66 1,123.21 1,014.50 1,229.82 <![CDATA[Total pore volume (cm 3 / g)]]> 0.847061 1.246288 1.389410 1.140810 1.245504 1.272677 1.245867 Equilibrium adsorption capacity (mg / g) 39.19 44.16 40.95 36.77 38.63 24.12 53.25

[0079] As shown in Table 1, the impregnation ratio of corn cob to phosphoric acid solution, calcination temperature, and holding time significantly affect the pore development and adsorption performance of the final biochar. Among them, the phosphoric acid-modified biochar (PBC-600-180-2) prepared in Example 7 exhibited the best overall performance: its specific surface area reached a maximum of 1229.82 m² / g, its total pore volume reached 1.245867 cm³ / g, and its initial equilibrium adsorption capacity for phenol also reached a peak of 53.25 mg / g. This indicates that the phosphoric acid etching effect was optimal under these parameters, greatly promoting the development of hierarchical pores within the biochar.

[0080] Example 8

[0081] A method for preparing a cuprous oxide-supported phosphoric acid-modified porous biochar composite material specifically includes the following steps: S1. Weigh 0.1g of the phosphoric acid modified porous biochar prepared in Example 7 and disperse it in 10mL of ultrapure water.

[0082] S2. Accurately weigh 0.01g CuSO4·5H2O and dissolve it in an appropriate amount of ultrapure water to prepare a copper salt solution.

[0083] S3. The solution was then added dropwise to the above suspension, and the mixed suspension was sonicated for 0.5 h, followed by continuous stirring at room temperature for 6 h.

[0084] S4. Slowly add 0.01 mol / L sodium hydroxide solution to the above suspension to adjust the pH of the system to 9.5.

[0085] S5. Preheat the system in a constant temperature oil bath at 60℃, then add glucose according to the molar ratio of glucose to copper sulfate of 1:2, and react at a constant temperature for 1.5h.

[0086] S6. After the reaction is complete, the product is subjected to solid-liquid separation, washed alternately with ultrapure water and anhydrous ethanol until neutral, and finally vacuum dried to obtain a composite adsorbent material with a copper content of 1.5%, denoted as 1.5%Cu2O / PBC.

[0087] Example 9 A method for preparing a cuprous oxide-supported phosphoric acid-modified porous biochar composite material is basically the same as that in Example 8, except that the mass of CuSO4·5H2O weighed in S2 is adjusted to 0.02g, and a composite adsorbent material with a copper content of 2.7% is finally obtained, which is denoted as 2.7%Cu2O / PBC.

[0088] Example 10 A method for preparing a cuprous oxide-supported phosphoric acid-modified porous biochar composite material is basically the same as that in Example 8, except that the mass of CuSO4·5H2O weighed in S2 is adjusted to 0.03g, and a composite adsorbent material with a copper content of 4.1% is finally obtained, which is denoted as 4.1%Cu2O / PBC.

[0089] Figure 1 The image shows the SEM image and elemental distribution of the composite material (2.7% Cu2O@PBC-100) from Example 9. As can be seen from the image, the biochar substrate possesses a rich porous structure, with a large number of nanoparticles uniformly loaded on its surface and within the pores, without significant agglomeration. Mapping results show that C, O, P, and Cu elements are highly uniformly distributed on the framework, confirming the successful construction of hierarchical channels and the in-situ growth of cuprous oxide.

[0090] The performance data of the phosphoric acid modified biochar in Examples 8-10 above are shown in Table 2: Table 2. Effects of cuprous oxide loading ratio on the pore structure and phenol adsorption efficiency of the composite material. <![CDATA[Specific surface area (m 2 / g)]]>< 1,175.42 1,108.65 996.24 <![CDATA[Total pore volume (cm 3 / g)]]> 1.152430 1.074522 0.942105 Equilibrium adsorption capacity (mg / g) 76.45 88.62 70.38

[0091] As shown in Table 2, the composite material (2.7% Cu2O@PBC-100) in Example 9 exhibits the highest equilibrium adsorption capacity for phenol, reaching 88.62 mg / g. Simultaneously, this material maintains a high specific surface area of ​​1108.65 m² / g, confirming that even after loading with Cu2O, the material retains a well-defined hierarchical porous structure.

[0092] Comparative Example 1

[0093] A method for preparing raw corn cob biochar includes the following steps: S1. Take 3g of dry corn cob powder, transfer it directly to the crucible and push it into the tube furnace.

[0094] S2. Under nitrogen atmosphere protection, heat to 500℃ at a heating rate of 5℃ / min and maintain the temperature for 3 hours.

[0095] S3. After the tube furnace has cooled naturally to room temperature, remove the carbonized product and grind it evenly in a ceramic mortar. Wash it repeatedly with ultrapure water three times, and then dry the washed biochar in a vacuum drying oven to constant weight to obtain the original corn cob biochar, labeled as BC.

[0096] Comparative Example 2

[0097] A method for preparing cuprous oxide-supported primary biochar includes the following steps: S1. Weigh 0.1g of the original biochar prepared in Comparative Example 1 and disperse it in 10mL of ultrapure water.

[0098] S2. Accurately weigh 0.02g CuSO4·5H2O and dissolve it in an appropriate amount of ultrapure water to prepare a copper salt solution.

[0099] S3. The mixed suspension was ultrasonically treated for 0.5 h, and then stirred continuously at room temperature for 6 h.

[0100] S4. Slowly add 0.01 mol / L sodium hydroxide solution to the above suspension to adjust the pH of the system to 9.5.

[0101] S5. Preheat the system in a constant temperature oil bath at 60℃, then add glucose according to the molar ratio of glucose to copper sulfate of 1:2, and react at a constant temperature for 1.5h.

[0102] S6. After the reaction is complete, the solid product is collected by centrifugation, washed alternately with ultrapure water and anhydrous ethanol until neutral, and finally vacuum dried to obtain cuprous oxide-supported original biochar composite material.

[0103] Comparative Example 3

[0104] A method for preparing pure cuprous oxide particles includes the following steps: S1. Accurately weigh 0.2g CuSO4·5H2O and dissolve it in an appropriate amount of ultrapure water to prepare a copper salt solution.

[0105] S2. Under stirring at room temperature, slowly add 0.01 mol / L sodium hydroxide solution to the above solution to adjust the pH of the system to 9.5. At this time, a blue flocculent precipitate of copper hydroxide is formed in the system.

[0106] S3. Preheat the above system in a constant temperature oil bath at 60℃, then add glucose according to the molar ratio of glucose to copper sulfate of 1:2, and react at a constant temperature for 1.5h.

[0107] S4. After the reaction is complete, centrifuge to collect the brick-red precipitate at the bottom, then wash it alternately with ultrapure water and anhydrous ethanol until neutral, and finally vacuum dry to obtain pure cuprous oxide particles.

[0108] Figure 2 The results show a comparison of the adsorption performance of the adsorbent materials prepared in Examples 7 and 9 and Comparative Examples 1-3 on phenol solution (50 mg / L). It is evident that the (Cu2O@PBC-100) prepared in Example 9 exhibits the best phenol removal performance. The above data fully demonstrates that a significant synergistic enhancement effect is generated between the hierarchical channels constructed by phosphoric acid modification and the in-situ supported Cu2O nanoparticles, successfully breaking through the adsorption capacity limit of a single component.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent, characterized in that, The method includes the following steps: S1. Wash, dry and crush corn cobs to obtain corn cob powder; then soak the corn cob powder in a 30%-85% phosphoric acid solution by mass, and after full impregnation, obtain a mixed precursor; S2. The mixed precursor is activated by high-temperature calcination under inert gas protection. After cooling, the solid product is washed and dried to obtain phosphoric acid modified biochar. S3. Disperse the phosphoric acid modified biochar in an aqueous solution containing soluble copper salt to allow it to be fully adsorbed and mixed. S4. Slowly add alkaline solution to the mixed system to adjust the system to be weakly alkaline. Then add a reducing agent under heating conditions to reduce the copper precursor in situ on the surface of biochar and in the micropores to generate cuprous oxide nanoparticles. S5. After the reaction is complete, the solid-liquid mixture is separated. The solid product is then washed alternately and dried under vacuum to obtain the composite adsorbent material.

2. The preparation method of the cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material according to claim 1, characterized in that, The mass ratio of corn cob to phosphoric acid solution is 1:1 to 1:3; the mass fraction of the phosphoric acid solution is 85%.

3. The preparation method of the cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material according to claim 1 or 2, characterized in that, In S2, the calcination activation temperature is 400-600℃, and the activation time is 2-3h; the inert gas is either nitrogen or argon.

4. The preparation method of the cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material according to claim 1 or 2, characterized in that, In S3, the soluble copper salt is one or a mixture of copper sulfate, copper nitrate, or copper chloride; the mass ratio of biochar to copper salt is 10:1-10:

3.

5. The method for preparing the cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material according to claim 1 or 2, characterized in that, In S4, the pH value of the mixed system is 9-11; the alkaline solution is at least one of sodium hydroxide, potassium hydroxide, or sodium carbonate.

6. The method for preparing the cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material according to claim 1 or 2, characterized in that, In S4, the reducing agent is at least one of glucose or ascorbic acid; the heating condition is at a temperature of 50-70°C.

7. The method for preparing the cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material according to claim 1 or 2, characterized in that, The soaking time in S1 is 12-24 hours; the mixing in S3 is ultrasonic dispersion for 1-2 hours.

8. A cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent prepared by the preparation method according to any one of claims 1-7.

9. The application of the cuprous oxide-supported phosphoric acid-modified biochar composite adsorbent material according to claim 8 in the treatment of phenol-containing wastewater.

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