Preparation method and application of calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst

Abstract

This invention discloses a calcium-rich biochar-enhanced dual-reaction-center Fenton-like catalyst. This system utilizes calcium-rich biochar as a solid-phase ligand, inorganic aluminum as the main crystal, and copper as a dopant. The introduction of calcium-rich biochar further enhances the redox interaction between electron-rich and electron-deficient regions caused by the electronegativity differences of the metal atoms. This system also leverages the key performance advantages of the calcium-rich biochar carrier, such as its abundant surface organic functional groups, well-developed pore structure, and the electron transport-promoting properties of the calcium carbonate component, to maximize the treatment of heavy metal-organic complexes in industrial wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment catalytic materials, and in particular to a preparation method and application of a calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst. Background Art

[0002] Fenton oxidation is an advanced oxidation technology based on the hydroxyl radical reaction principle, enabling the non-selective oxidative degradation and mineralization of refractory pollutants in aquatic environments. It is widely applicable to the pretreatment or advanced treatment of a variety of sewage / wastewater types, including dye wastewater, phenolic wastewater, landfill leachate, and pharmaceutical wastewater. However, in practical applications, Fenton oxidation suffers from limitations such as a narrow pH range, difficulty in catalyst recovery, high H₂O₂ consumption, and high iron-containing sludge production, limiting its further application. To address the technical limitations of traditional Fenton oxidation, the development of efficient and stable heterogeneous Fenton-like catalysts has become a research hotspot in the field of environmental catalysis.

[0003] Based on the theory of electron distribution polarization, the use of crystal phase doping technology to construct heterogeneous Fenton-like catalysts with dual reaction centers and the enhancement of electron transport through organic functional group ligands are effective approaches to address the problems of traditional Fenton oxidation technology. For example, the prior art "An In-situ Doped Cobalt-Based Fenton Catalyst, Synthesis Method, and Application thereof" discloses adding a cobalt source to precursors such as melamine, monocyanamide, dicyandiamide, or urea, followed by an in-situ doping and calcination process to synthesize the in-situ doped cobalt-based Fenton catalyst. The prior art "A Surface Solid-Phase Ligand-Enhanced Fenton Catalyst, Preparation Method, and Application thereof" discloses baking a precursor metal solution to form a xerogel, calcining it at high temperature, and then mixing and calcining it with a urea aqueous solution to obtain a surface ligand-enhanced Fenton catalyst. While these heterogeneous Fenton-like catalysts offer significant advantages in catalytic activity, catalytic stability, efficient H2O2 utilization, and pollutant removal, they still have limitations in terms of catalyst preparation, pollutant treatment targets, and the type of surface solid-phase ligand. Patent CN 107930694 A discloses a surface-solid-phase ligand-enhanced Fenton catalyst, its preparation method, and its application. However, the preparation process is relatively complex and involves numerous control steps. Furthermore, existing catalysts are only applicable to a limited range of pollutants, primarily aromatic organic compounds such as bisphenol A, diphenhydramine, ciprofloxacin, phenytoin, and 2-chlorophenol. Furthermore, existing catalysts utilize relatively few solid-phase ligands, primarily carbonized nitrogen, graphene, and graphene quantum dots. Developing heterogeneous Fenton-like catalysts with simplified preparation processes, superior overall performance, and a wide range of solid-phase ligand sources has become a pressing goal for researchers. Summary of the Invention

[0004] In view of the above-mentioned prior art, the purpose of the present invention is to provide a preparation method and application of a calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst, using calcium-rich biomass waste as a carbonaceous precursor, and preparing an efficient and stable heterogeneous Fenton-type catalyst through ultrasonic blending, hydrothermal carbonization, high-temperature calcination and other methods.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a method for preparing a calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst, comprising the following steps:

[0007] S1: dissolving an inorganic metal salt and glucose in deionized water in sequence, and adding a calcium-rich biomass waste raw material under ultrasonication to obtain a suspension system with uniformly dispersed particles, and subjecting the obtained suspension system to a hydrothermal reaction under magnetic stirring conditions;

[0008] S2: After the reactor is naturally cooled to room temperature, the product obtained in step S1 is washed and dried;

[0009] S3: The dried product of step S2 is calcined at high temperature, cooled, and then ground and sieved to obtain the calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst.

[0010] Preferably, in step S1, the mass ratio of the inorganic metal salt, glucose, and calcium-rich biomass waste raw material is (6-7):(3-8):1.

[0011] Preferably, the inorganic metal salt is a metal aluminum salt and a metal copper salt, the metal aluminum salt is Al(NO3)3, and the metal copper salt is Cu(NO3)2 or CuCl2; the mass ratio of the metal aluminum salt to the metal copper salt is 10:1.

[0012] More preferably, the calcium-rich biomass waste raw material is calcium-rich rice husk powder, the calcium content of which is 10-15%, and the particle size of which is 500-1000 mesh.

[0013] Preferably, in step S1, the ultrasonic frequency is 30-50 kHz and the time is 20-40 min.

[0014] Preferably, in step S1, the hydrothermal temperature is 150-250° C., the reaction time is 15-25 h, and the stirring speed is 300-500 rpm.

[0015] Preferably, in step S3, the high-temperature calcination temperature is 550° C., the calcination time is 3-5 h, the heating rate is 5° C. / min, and the grinding particle size is 100 mesh.

[0016] The second aspect of the present invention provides a calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst obtained by the above preparation method.

[0017] The third aspect of the present invention provides the application of the above-mentioned calcium-rich biochar-enhanced dual-reaction center Fenton catalyst in the pretreatment or deep treatment of heavy metal-organic complexes in industrial wastewater. For heavy metal-organic complex wastewater with a pH value of 3-8, the above-mentioned calcium-rich biochar-enhanced dual-reaction center Fenton catalyst is added under magnetic stirring, and then H2O2 solution is added dropwise to react for 60-120 minutes.

[0018] Preferably, the heavy metal-organic complex wastewater is a complex pollutant wastewater formed by the coordination of Ni and EDTA; the addition amount of the calcium-rich biochar-enhanced dual-reaction center Fenton catalyst is 1-3 g / L, and the addition amount of H2O2 is 0.05-0.1 mol / L.

[0019] The calcium-rich biochar-enhanced dual-reaction center Fenton-like catalyst prepared by the present invention through ultrasonic blending, hydrothermal carbonization and high-temperature calcination process is mostly irregular spherical, and the catalyst surface is composed of elements such as Al, O, C, Cu, Ca, Si, Mg, etc., and each element is evenly distributed. In the catalyst, Al is mainly in the form of Al 3+ and Al 3+ δ exists in the form of Cu, and Cu element mainly exists in the form of Cu 2+ and Cu + exists in the form of Cu + While the crystal phase doping constructs Al-O-Cu bonds, the introduction of calcium-rich biochar not only complexes with Cu within the crystal framework but also secures more Cu oxides to the catalyst surface through the formation of CO-Cu bonds. The resulting electron polarization distribution fosters the formation of an electron-rich, high-density region centered on Cu and an electron-deficient, low-density region centered on Al and C (i.e., the aromatic ring structure). Furthermore, the π system in the aromatic ring structure has a stronger electron-donating capacity for Cu than Al does for Cu.

[0020] During the preparation process, copper salt, aluminum salt, and glucose are pre-blended to form a complex system. Ultrasound is then applied to the calcium-rich biomass, promoting its adsorption of copper. This ensures copper is doped within the alumina crystal structure while also forming more Cu-O-C bonds on the biochar surface, increasing the Cu loading. During the hydrothermal reaction, glucose first forms glucose-carbon microspheres through reactions such as dehydration condensation. Aluminum salt adsorbs on the surface of the microspheres to form pseudo-boehmite. During this process, the calcium-rich biomass undergoes carbonization and introduces oxygen-containing functional groups, which are more inclined to pore-filling distribution and tightly bind to copper. During calcination, some glucose-derived and rice husk biochar are converted to carbon dioxide, and the pseudo-boehmite on their surfaces is converted to γ-Al2O3. The aromatic rings of the biochar are connected to the copper via CO-Cu bonds. Since CaCO3 has a high decomposition temperature (>600°C), its structure remains unchanged during the preparation process. After the reaction, aluminum serves as the primary core, while copper, while also serving as a core, is directly distributed on the catalyst surface, bonding with carbon. Carbon and calcium carbonate are more uniformly distributed over the surface. This method utilizes ultrasonic blending, hydrothermal carbonization, and high-temperature calcination at 550°C to preserve the original calcium carbonate in the rice husk.

[0021] The catalyst is accompanied by graphite and CaCO3 crystal phase structures. The conduction band electrons in the graphite structure can move freely within the crystal plane, have high electron mobility and conductivity, and facilitate electron transfer between π→Cu. Calcium carbonate can not only adsorb and remove heavy metals, but also has good ionization and conductivity properties, which can promote the transmission of electrons and holes and accelerate the oxidation and degradation reaction of pollutants. Regarding the role of calcium carbonate, only a small amount of literature involves its application in photocatalysts, which is different from the materials in this application, and its mechanism of action is still unclear.

[0022] At present, the research focus of dual-reaction center catalysts is on the construction of metal systems with different electronegativities, or the construction of electron transfer systems of non-carbon materials and the catalytic efficiency and principles. There are relatively few studies involving the enhancement of carbonaceous materials. Since the composition system and performance regulation of biochar are relatively complex, its composition and structure affect the catalytic efficiency of the catalyst, which leads to difficulties in biomass screening. In addition, the types of solid-phase ligands used in the preparation of existing catalysts are limited. Therefore, the present invention uses calcium-rich biochar as a solid-phase ligand to expand the types of ligands.

[0023] In the present invention, the working principle of calcium-rich biochar is divided into the following aspects: (1) constructing CO-Cu bonds to achieve electron transfer between π and Cu; (2) synergistically acting with Al-O-Cu bonds to further enhance electron transfer; (3) loading and binding more Cu, which can be separated from the Al2O3 crystal structure and dispersed on the biochar surface; (4) More importantly, the calcium carbonate coexisting in the biochar plays an electron transfer role, while oxidizing and destroying the structure of heavy metal complexes, it also adsorbs and removes heavy metals. The calcium carbonate here is not generated by a later reaction, but is already present in the raw materials themselves. Among them, aspects (3) and (4) are different from previous studies or have not been reported in previous studies.

[0024] In the prior art, since there are many impurities in biochar, the biochar is acid-washed to remove impurities and improve catalytic performance. In the early stages of the experiment, the present invention did not use acid washing. The main purposes were (1) to reduce the number of pretreatment steps in the early stage and (2) to save costs from the perspective of industrial application by simply washing with water to remove impurities. In order to study the reaction principle during the reaction process, especially the role of biochar and its coexisting impurities, the biochar was acid-washed, and it was unexpectedly discovered that the calcium carbonate originally present in the biomass has a strengthening effect on catalysis during the reaction process, achieving unexpected technical results.

[0025] Beneficial effects of the present invention:

[0026] This invention constructs a heterogeneous Fenton-like catalytic system using calcium-rich biochar as a solid-phase ligand, inorganic aluminum as the main crystal, and copper as a dopant. The introduction of calcium-rich biochar further enhances the redox effects of electron-rich and electron-deficient regions caused by the electronegativity differences of the metal atoms. It also leverages the key performance advantages of the calcium-rich biochar carrier, such as its abundant surface organic functional groups, well-developed pore structure, and the electron transport-promoting properties of the calcium carbonate component, to maximize the treatment of heavy metal-organic complexes in industrial wastewater.

[0027] Under the condition of an initial pH value of 3-8, after 90 minutes of treatment, the catalyst of the present invention can achieve a heavy metal complex decomposition efficiency of more than 91%, and the Cu dissolution amount is less than 0.2 mg / L, showing a wide pH application range and excellent catalytic reaction characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 : SEM-EDS image of the calcium-rich biochar-enhanced dual-reaction-center Fenton-like catalyst in Example 1;

[0029] Figure 2 : XPS full spectrum of the calcium-rich biochar-enhanced dual-reaction-center Fenton-like catalyst in Example 1 and fine spectra of Cu and Al elements;

[0030] Figure 3 : XRD patterns of three different dual-reaction-center Fenton-like catalysts in Example 1 and Comparative Examples 1-2;

[0031] Figure 4 : Comparative diagram of the removal effects of heavy metal-organic complexes under three different catalyst conditions in Example 1 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0033] As described in the background technology, based on this, the present invention provides a calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst, which is prepared by the following steps:

[0034] S1: dissolving an inorganic metal salt and glucose in deionized water in a proportional manner, adding a calcium-rich biomass waste raw material, and subjecting the suspension system to a 30-50 kHz ultrasonic treatment for 20-40 minutes to obtain a suspension system with uniformly dispersed particles. The suspension system is subjected to a hydrothermal reaction under magnetic stirring at 300-500 rpm at a hydrothermal temperature of 150-250° C. for a reaction time of 15-25 hours.

[0035] The mass ratio of inorganic metal salt, glucose and calcium-rich biomass waste raw materials is (6-7):(3-8):1.

[0036] The inorganic metal salts are aluminum salts and copper salts, wherein the aluminum salt is Al(NO3)3 and the copper salt is Cu(NO3)2 or CuCl2; the ratio of the aluminum salt to the copper salt is 10:1; the calcium-rich biomass waste raw material is calcium-rich rice husk powder, which has a calcium content of 10-15% and a particle size of 500-1000 mesh;

[0037] S2: After the reactor is naturally cooled to room temperature, the product obtained in step S1 is washed and dried;

[0038] S3: The dried product of step S2 is placed in a muffle furnace and calcined at 550°C for 3-5 hours at a heating rate of 5°C / min. After cooling, the product is ground into 100 mesh and sieved to obtain the calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst.

[0039] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0040] The experimental materials used in the examples of the present invention are all conventional experimental materials in the field and can be purchased through commercial channels. The calcium-rich rice husk powder used in the following examples and comparative examples of the present invention was purchased from Lianfeng Agricultural Products Deep Processing Factory in Lianyungang, Jiangsu Province.

[0041] Example 1

[0042] A method for preparing a calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst comprises the following steps:

[0043] Step S1: weigh 7.5 g Al(NO3)3·9H2O, 0.75 g Cu(NO3)2·3H2O and 5.0 g C6H 12 O6 was dissolved in 55 mL of deionized water, and 1.325 g of 1000-mesh calcium-rich rice husk powder with a calcium content of 13.28% was added. After being ultrasonicated at 40 kHz for 30 min, a suspension system with uniformly dispersed particles was obtained. The suspension system was transferred to a 100 mL hydrothermal reactor and hydrothermally reacted at 200°C for 20 h under magnetic stirring.

[0044] Step S2: After the reactor is cooled to room temperature naturally, the obtained product is washed with water several times and dried in a forced air drying oven at 80°C;

[0045] Step S3, transferring the dried product of step S2 into a corundum boat and covering it, calcining it at 550°C in a muffle furnace for 4 hours at a heating rate of 5°C / min, and grinding it through a 100-mesh sieve after cooling to obtain a calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst.

[0046] The calcium-rich biochar-enhanced dual-reaction center Fenton-like catalysts prepared by ultrasonic mixing, hydrothermal carbonization and high-temperature calcination are mostly irregular spherical (such as Figure 1 As shown in Figure 2), the catalyst surface is composed of elements such as Al, O, C, Cu, Ca, Si, and Mg, and each element is evenly distributed. XPS results (as shown in Figure 2) Figure 2 As shown in Figure 2, it is shown that the Al in the catalyst is mainly in the form of Al 3+ and Al 3+ δ exists in the form of Cu, and Cu element mainly exists in the form of Cu 2+ and Cu + exists in the form of Cu +Most of them. While the crystal phase doping constructs the Al-O-Cu bond, the introduction of calcium-rich biochar can not only complex with Cu in the crystal framework, but also fix more Cu oxides on the catalyst surface by forming CO-Cu bonds. The electronic polarization distribution generated under this action promotes the formation of an electron-rich high-density region centered on Cu and an electron-deficient low-density region centered on Al and C (i.e., aromatic ring structure). Compared with the electron-donating ability of Al to Cu, the electron-donating ability of the π system in the aromatic ring structure to Cu is stronger. XRD analysis results show that (such as Figure 3 The catalyst is composed of graphite and CaCO3 crystal phases. The graphite structure allows conduction band electrons to move freely within the crystal plane, resulting in high electron mobility and conductivity, facilitating electron transfer from π to Cu. Calcium carbonate not only adsorbs and removes heavy metals but also exhibits excellent ionization and conductivity, promoting electron and hole transport and accelerating the oxidative degradation of pollutants.

[0047] Comparative Example 1

[0048] A method for preparing a biochar-enhanced dual-reaction-center Fenton-type catalyst comprises the following steps:

[0049] Step S1, placing 1.325 g of calcium-rich rice husk powder in 50 mL of 1 mol / L HCl solution, stirring magnetically for 24 h, and then washing with deionized water until the pH value of the supernatant is neutral;

[0050] Step S2: weigh 7.5 g Al(NO3)3·9H2O, 0.75 g Cu(NO3)2·3H2O and 5.0 g C6H 12 O6 was dissolved in 55 mL of deionized water, and the acid-washed rice husk powder in step S1 was added. After being ultrasonicated at 40 kHz for 30 min, a suspension system with uniformly dispersed particles was obtained. The suspension system was transferred to a 100 mL hydrothermal reactor and hydrothermally reacted at 200°C for 20 h under magnetic stirring conditions;

[0051] Step S3, after the reactor is naturally cooled to room temperature, the obtained product is washed with water several times and dried in a forced air drying oven at 80°C;

[0052] Step S4, transferring the dried product of step S3 into a corundum boat and covering it, calcining it at 550°C in a muffle furnace for 4 hours at a heating rate of 5°C / min, and grinding it through a 100-mesh sieve after cooling to obtain the biochar-enhanced dual-reaction center Fenton-type catalyst Cu-Al2O3-ABC.

[0053] In this comparative example, the calcium-rich biochar was acid-washed, and the rest was the same as in Example 1.

[0054] The XRD analysis results show that ( Figure 3 As shown in the figure), compared with Cu-Al2O3, the catalyst Cu-Al2O3-ABC has a graphite crystal structure but no CaCO3 crystal structure, which indicates that the graphite structure in biochar can promote the polarization distribution of electron cloud on the catalyst surface, thereby enhancing the performance of the dual reaction center catalyst.

[0055] Comparative Example 2

[0056] A method for preparing a dual-reaction-center Fenton-type catalyst comprises the following steps:

[0057] Step S1: weigh 7.5 g Al(NO3)3·9H2O, 0.75 g Cu(NO3)2·3H2O and 5.0 g C6H 12 O6 was dissolved in 55 mL of deionized water and subjected to 40 kHz ultrasound for 30 min to obtain a suspension system with uniformly dispersed particles. The suspension system was transferred to a 100 mL hydrothermal reactor and subjected to hydrothermal reaction at 200 °C for 20 h under magnetic stirring conditions.

[0058] Step S2: After the reactor is cooled to room temperature naturally, the obtained product is washed with water several times and dried in a forced air drying oven at 80°C;

[0059] Step S3, transferring the dried product of step S2 into a corundum boat and covering it, calcining it at 550°C in a muffle furnace for 4 hours at a heating rate of 5°C / min, and grinding it through a 100-mesh sieve after cooling to obtain the dual-reaction center Fenton-type catalyst Cu-Al2O3.

[0060] In this comparative example, no calcium-rich biochar was added, and the rest was the same as in Example 1.

[0061] Experimental example

[0062] A comparative catalytic oxidation experiment was conducted on the catalysts prepared in Example 1 and Comparative Examples 1-2 to further illustrate the performance advantages of the calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst. The specific steps are as follows:

[0063] Measure 50mL Ni-EDTA simulated wastewater (10mg / L, Ni 2+ Ion concentration meter) in the reactor, and then add 2g / L catalyst and 75mmol / L H2O2 in sequence to react. During the reaction, 1mL of sample was regularly taken into a colorimetric tube, and then appropriate amounts of Na2SO3 and NaOH were added to terminate the reaction and remove free Ni in the solution. 2+ The sample was diluted and filtered through a 0.45 μm microporous membrane to detect Ni 2+ The results are as follows Figure 4As shown, Cu-Al2O3-BC is the catalyst prepared in Example 1, Cu-Al2O3-ABC is the catalyst prepared in Comparative Example 1, and Cu-Al2O3 is the catalyst prepared in Comparative Example 2.

[0064] Under the condition of an initial pH value of 5, after 90 minutes of treatment, the decomposition efficiency of the heavy metal complex of Example 1 reached 96.7%, and the amount of Cu dissolved was less than 0.2 mg / L.

[0065] Depend on Figure 4 It can be seen that after 90 minutes of catalytic oxidation reaction, the complex breaking efficiency of the dual-reaction center Fenton-like catalyst Cu-Al2O3 in Comparative Example 2 is only 22.5%, which is much lower than the complex breaking efficiency of the Fenton-like catalyst (Cu-Al2O3-BC) under the conditions of calcium-rich biochar doping in Example 1 (96.7%), which indicates the strengthening effect of calcium-rich biochar on the dual-reaction center Fenton-like catalyst.

[0066] In the initial stages of the present invention, acid washing was not employed. The main objectives were (1) to reduce the number of pretreatment steps and (2) to achieve cost savings from an industrial application perspective by removing impurities through simple water washing. To clarify the reaction mechanism during the reaction, particularly the role of biochar and its coexisting impurities, the biochar was acid washed (Comparative Example 1), and it was unexpectedly discovered that the calcium carbonate originally present in the biomass had a catalytic enhancing effect during the reaction.

[0067] In Comparative Example 1, after the impurities in the biochar, especially calcium carbonate, were removed by acid washing, the decomposition efficiency of the catalyst (Cu-Al2O3-ABC) was reduced to 69.3%, indicating that calcium carbonate in the biochar has a synergistic effect on the performance of the Fenton-like catalyst.

[0068] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. Application of a calcium-rich biochar-enhanced dual-reaction center Fenton-like catalyst in the pretreatment or deep treatment of heavy metal-organic complexes in industrial wastewater, characterized in that: The calcium-rich biochar-enhanced dual-reaction center Fenton-type catalyst is prepared by the following method: S1. Dissolving an inorganic metal salt and glucose in deionized water in sequence, and adding a calcium-rich biomass waste raw material under ultrasonication to obtain a suspension system with uniformly dispersed particles, and subjecting the resulting suspension system to a hydrothermal reaction under magnetic stirring conditions; wherein the inorganic metal salt is a metal aluminum salt and a metal copper salt, the metal aluminum salt is Al(NO3)3, and the metal copper salt is Cu(NO3)2 or CuCl2; the mass ratio of the metal aluminum salt to the metal copper salt is 10:1; and the calcium-rich biomass waste raw material is calcium-rich rice husk powder, having a calcium content of 10-15% and a particle size of 500-1000 mesh; S2. After the reactor is cooled to room temperature, the product obtained in step S1 is washed and dried; S3. The dried product of step S2 is calcined at high temperature, cooled, ground and sieved to obtain the calcium-rich biochar-enhanced dual-reaction center Fenton catalyst; The specific application steps are: for heavy metal-organic complex wastewater with a pH value of 3-8, the calcium-rich biochar-enhanced dual-reaction center Fenton catalyst as described above is added under magnetic stirring, and then H2O2 solution is added dropwise to react for 60-120 minutes.

2. The use according to claim 1, characterized in that In step S1, the mass ratio of the inorganic metal salt, glucose, and calcium-rich biomass waste raw material is (6-7):(3-8):

1.

3. The use according to claim 1, characterized in that In step S1, the ultrasonic frequency is 30-50 kHz and the time is 20-40 min.

4. The use according to claim 1, wherein In step S1, the hydrothermal temperature is 150-250° C., the reaction time is 15-25 h, and the stirring speed is 300-500 rpm.

5. The use according to claim 1, characterized in that In step S3, the high-temperature calcination temperature is 550° C., the calcination time is 3-5 h, the heating rate is 5° C. / min, and the grinding particle size is 100 mesh.

6. The use according to claim 1, wherein The heavy metal-organic complex wastewater is complex pollutant wastewater formed by the coordination of Ni and EDTA; the addition amount of the calcium-rich biochar-enhanced dual-reaction center Fenton catalyst is 1-3 g / L, and the addition amount of H2O2 is 0.05-0.1 mol / L.

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