Modified biochar catalyst as well as preparation method and application thereof

Abstract

The invention discloses a modified biochar catalyst as well as a preparation method and application thereof, and belongs to the technical field of industrial wastewater treatment. The catalyst comprises a carrier: biochar having a porous structure; and the active component is an oxide which is loaded on the carrier and contains a plurality of cerium. The catalyst is beneficial to generation of oxygen vacancies and has oxygen storage / release capacity, so that ozone is catalyzed to directionally generate singlet oxygen active species, and the oxidation selectivity to pollutants is improved. The catalyst provided by the invention is used for treating complex electroplating wastewater containing heavy metal complexes, and can realize high-selectivity oxidation complex breaking and synchronous adsorption and recovery of heavy metals; meanwhile, the catalyst shows high catalytic activity in a wide pH range, can be repeatedly used and is high in complex water body interference resistance.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment technology, and more specifically, relates to a modified biochar catalyst, its preparation method, and its application. Background Technology

[0002] The electroplating industry is an important part of the national economy, but the large amounts of wastewater generated during its production process contain various heavy metals (such as Zn, Fe, Cr, Ni, Cd, Au, and Cu) and organic pollutants, posing a serious threat to the environment. Heavy metals in electroplating wastewater mainly exist in stable complex forms, and traditional treatment methods often fail to achieve ideal treatment results. In recent years, advanced oxidation technologies have received widespread attention in the field of electroplating wastewater treatment due to their high efficiency and thoroughness.

[0003] In advanced oxidation technologies, selective oxidation by catalysts is a crucial issue. Selective oxidation refers to the preferential oxidation of target pollutants under the action of a catalyst, with minimal influence from other coexisting components. In electroplating wastewater treatment, selective oxidation is particularly important due to the complex composition of the wastewater. Currently, most optimizations of selective oxidation are achieved by controlling the composition, structure, and surface properties of the catalyst. For example, in photocatalytic oxidation, the band structure of the catalyst is adjusted by doping with specific elements or constructing heterojunctions, thereby improving the selectivity for the degradation of target pollutants. In Fenton oxidation, the oxidation capacity for specific organic compounds is enhanced by introducing ligands or using supported catalysts. In recent years, ozone oxidation technology has been widely used in electroplating wastewater treatment due to its strong oxidizing power and lack of secondary pollution. However, due to the complex composition of electroplating wastewater, ozone oxidation suffers from low selectivity. First, the complex composition of electroplating wastewater may lead to competitive reactions between different pollutants, affecting selectivity; second, the stability of the catalyst has not been fully resolved, and long-term operation may lead to a decrease in selectivity; third, pursuing selectivity at the expense of oxidation efficiency may reduce oxidation efficiency, making the balance between selectivity and oxidation efficiency a challenging problem. Therefore, developing efficient catalysts to break down complexed heavy metals has become one of the key research areas in the environmental field.

[0004] A search revealed that patent CN117339562A discloses the preparation and application of cerium-modified coconut shell biochar. The method includes steps S1: preparation of cerium-modified biochar; impregnating the biochar in a cerium chloride solution, stirring, adding sodium hydroxide to adjust the pH to obtain cerium hydroxide precipitate, centrifuging, washing, and drying; and S2: adsorption; weighing the cerium-modified biochar and adding it to a KH₂PO₄ solution, shaking for 24 hours to adsorb phosphorus from the solution. However, in this method, cerium exists in the form of cerium hydroxide in the cerium-modified biochar, and it is only used for physical adsorption, making it difficult to remove complexed heavy metals.

[0005] Patent CN118253307A discloses an iron-magnesium modified biochar catalyst, its preparation method, and its application. The steps are as follows: an iron source, a magnesium source, and a cerium source are stirred and dissolved; a biomass carbon source is added; the mixture is heated and stirred to obtain a paste; and then dried and calcined under limited oxygen conditions to obtain the catalyst. This catalyst is used to activate persulfate to degrade tetracycline. Patent CN119080205A discloses an ozone catalytic oxidation wastewater treatment device and method. The treatment device is filled with a catalyst, which includes a catalyst support, an active component, and an adsorption component. The catalyst support is a molecular sieve. The active component includes one or more oxides of Fe, Ru, Mn, Cu, Ni, Zn, Co, Ce, and La. The adsorption component includes activated carbon; the activated carbon includes at least two or more of coal-based activated carbon, coconut shell activated carbon, and fruit shell activated carbon. This patent describes a process where a catalyst support, active component, and adsorbent component are blended to form a precursor, which is then integrally molded and calcined to obtain the catalyst. The active component includes Fe₂O₃, CuO, RuO, and ZnO, which are blended with the other components in oxide form before calcination. Both of the aforementioned patents introduce other components into the catalyst for co-firing, resulting in cerium oxides existing in amorphous, low-crystallinity, or other mixed forms, leading to catalysts with poor selectivity. Summary of the Invention

[0006] 1. The problem to be solved

[0007] To address the problems of poor interference resistance, poor selectivity and stability of existing ozone catalysts, which make them unsuitable for the degradation of complex copper plating wastewater, the primary objective of this invention is to provide a modified biochar catalyst. A second objective of this invention is to provide a method for preparing the above-mentioned modified biochar catalyst; The third objective of this invention is to provide the application of the above-mentioned modified biochar catalyst in the treatment of complexed heavy metal wastewater, which can achieve complex breaking and simultaneous efficient recovery of heavy metal electroplating wastewater containing complex matrix components.

[0008] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of this invention discloses a modified biochar catalyst, comprising: Carrier: Biochar, which has a porous structure; Active component: Oxides containing cerium supported on a carrier; The oxides of cerium include CeO. 2-x In the formula, x≥0.

[0009] In one feasible embodiment, the cerium oxide includes cerium dioxide (CeO2), cerium trioxide (Ce2O3), and non-stoichiometric cerium oxide (CeO2). 2-x ), which is a composite phase of various cerium oxides.

[0010] CeO2 has a cubic fluorite structure, forming the main structural component, while Ce2O3 is mainly enriched in non-stoichiometric CeO. 2-x And in the surface active sites of CeO2, non-stoichiometric cerium oxide (CeO) 2-x It is rich in oxygen vacancies and mainly exists in the surface, grain boundaries and defects of cerium dioxide (CeO2) with a cubic fluorite structure.

[0011] The aforementioned multivalent cerium oxides exhibit synergistic effects: tetravalent cerium (Ce(IV)), primarily located in the cubic fluorite CeO2 framework, serves as a stable structural matrix and electron reservoir, maintaining the overall stability of the catalyst and providing the thermodynamic driving force for redox cycles; trivalent cerium (Ce(III)) is mainly enriched in non-stoichiometric CeO2. 2-x And within the surface active sites, it directly drives catalytic function, which selectively activates ozone generation through the accompanying oxygen vacancies. 1 O2 (singlet oxygen) efficiently breaks down complexes, improving their anti-interference properties, and acts as a strong electron donor to release Cu from the broken complex. 2+ In-situ reduction to Cu + This achieves the chemical fixation and resource recovery of copper. More importantly, Ce(III) and Ce(IV) form a dynamic cycle through reversible electron transfer. This cycle not only continuously regenerates oxygen vacancies and active Ce(III) sites, ensuring long-term catalytic efficacy, but also interacts with Cu... 2+ / Cu + The conversion process is coupled to form a bimetallic synergistic catalytic network, which ultimately enables the catalyst to simultaneously possess the properties of high selective oxidation, efficient recovery of heavy metals, strong anti-interference, and self-enhancing stability.

[0012] According to any embodiment of the first aspect of the present invention, in the modified biochar catalyst, cerium is present as Ce(III), Ce(IV) and Ce(4-2x) in a non-stoichiometric ratio, wherein Ce(III) accounts for 15%-40% of the total cerium (Ce(III) + Ce(IV) + Ce(4-2x)), preferably 20%-35%.

[0013] Among them, the Ce(III) content is ≥15% to ensure a sufficient concentration of Ce(III) to form the necessary oxygen vacancies, driving... 1 O2 generation and Cu 2+The reduction of Ce(III) content should be ≤40% to avoid excessive distortion of the crystal structure due to excessive Ce(III) content, which would affect the thermal stability and mechanical strength of the catalyst.

[0014] According to any embodiment of the first aspect of the invention, the modified biochar catalyst, wherein the cerium dioxide has a cubic fluorite structure.

[0015] This application utilizes a specific preparation process to obtain cerium dioxide with a cubic fluorite crystal structure, which is beneficial for improving the catalytic generation of ozone. 1 The selectivity of O2 leads to the formation of high-concentration, stable, and highly catalytically active oxygen vacancies.

[0016] Among them, the cubic fluorite structure, compared with other crystals such as the hexagonal structure, is more likely to form surface oxygen vacancies and has suitable active crystal faces, which is beneficial for catalyzing the generation of O3 in the reversible cycle of Ce(III) and Ce(IV). 1 O2 improves the selectivity and catalytic efficiency of catalysts.

[0017] (1) Oxygen vacancy The cubic fluorite structure has an open calcium fluoride-type structure, which allows for high oxygen ion mobility and low oxygen vacancy formation energy. This means that under mild reaction conditions, a large number of oxygen vacancies can be generated on the surface and subsurface. These oxygen vacancies are active sites for activating O3 molecules and initiating selective oxidation pathways.

[0018] Other structures, such as hexagonal structures, typically have a more compact atomic packing or different coordination environments, resulting in a higher oxygen vacancy formation energy and therefore a lower oxygen vacancy concentration and lower catalytic performance.

[0019] (2) Ce 3+ / Ce 4+ Redox Cycle Cubic fluorite structures can accommodate a high proportion of Ce. 3+ Without causing severe lattice distortion, its structural framework is Ce. 3+ and Ce 4+ The coexistence provides a flexible space, in which Ce 3+ Ce has a large ionic radius. 4+ With its small ionic radius, the cubic fluorite structure achieves Ce2+ through the formation of oxygen vacancies and dynamic redox cycles. 3+ and Ce 4+ Coexistence, avoiding high-valence Ce 4+ Restored to Ce 3+ This prevents structural instability, sintering or deactivation of the active phase caused by time, ensuring the high reversibility and stability of the redox cycle.

[0020] (3) Exposed active crystal facets The cubic fluorite structure includes (111), (110), and (100) crystal planes, which facilitate oxygen adsorption / desorption, oxygen vacancy formation, and specific reaction pathways such as O3 orientation. 1 The conversion of O2 has optimal surface energy and geometry.

[0021] Furthermore, although the amorphous or non-crystalline CeO2 formed by traditional blending and calcination has a high specific surface area and abundant defects, its structure is disordered, the oxygen vacancy properties are inhomogeneous, and the Ce valence state distribution is broad, which can easily lead to a chaotic catalytic pathway and make it impossible to accurately guide the conversion of O3 to CeO2. 1 O2 may increase the yield of non-selective active species ·OH, thereby weakening the anti-interference ability.

[0022] According to any embodiment of the first aspect of the present invention, the modified biochar catalyst has an active component loading of 1 wt% to 10 wt%, preferably 2 wt% to 6 wt%.

[0023] If there are too few active components, it is difficult to form an effective catalytic active site network, and the catalytic enhancement effect is not obvious; if there are too many active components, they are prone to excessive aggregation on the surface of the support and in the pores, blocking the micropores with high specific surface area, resulting in a decrease in the specific surface area of ​​the catalyst and a decrease in the utilization rate of active components.

[0024] According to any embodiment of the first aspect of the present invention, the modified biochar catalyst of the support has an average pore size of 2-8 nm, preferably 3.0-5.0 nm, and a porosity of 0.25-0.6 cm⁻¹. 3 / g, preferably 0.33-0.40 cm³ / g; specific surface area is 700-1100 m² / g, preferably 800-900 m² / g.

[0025] According to any embodiment of the first aspect of the present invention, the modified biochar catalyst is a support of biochar, including one or more of coconut shell char, walnut shell char, and apricot kernel char. Preferably, the biochar is coconut shell char, which has sub-nanometer hierarchical channels, high mechanical strength, and rich surface chemical properties.

[0026] Preferably, the coconut shell charcoal comprises macropores (>50 nm), mesopores (2-50 nm), and sub-nanometer micropores (0.3-0.8 nm). This structure not only provides a highly dispersed loading space for the active components, but its strong enrichment effect significantly improves the local reaction concentration and catalytic efficiency; more importantly, the confined environment created by the sub-nanometer micropores is conducive to the conversion of ozone to singlet oxygen (…). 1The directional activation of O2 enhances oxidation selectivity, while its pore size screening effect effectively reduces the poisoning of active sites by macromolecular organic matter. However, the original biochar has poor catalytic ability. By doping with Ce, which has excellent oxygen storage / release capacity and oxygen storage capacity, it is beneficial to generate oxygen vacancies and form a singlet oxygen active component with stronger selectivity, thereby improving the selectivity, anti-interference ability and stability of the catalyst.

[0027] The second aspect of this invention discloses a method for preparing the above-mentioned modified biochar catalyst, which includes the following steps: Step S1, Impregnation: Dissolve the cerium source to obtain a cerium salt solution, add the bio-carbon source to the cerium salt solution, sonicate for several hours, let stand overnight, and then dry. Step S2, pyrolysis: calcination treatment to obtain modified biochar catalyst.

[0028] According to any embodiment of the second aspect of the present invention, in the method for preparing a modified biochar catalyst, in step S1, the cerium source includes one or more of cerium nitrate, cerium chloride, cerium sulfate, cerium ammonium nitrate, and cerium carbonate; preferably cerium nitrate, which has good thermal decomposition behavior and no harmful residues, and the concentration of the cerium salt solution is preferably 0.1-0.15M.

[0029] According to any embodiment of the second aspect of the present invention, in the method for preparing the modified biochar catalyst, in step S1, the ultrasonic treatment time is 4-5 h and the drying temperature is 120-130 °C.

[0030] According to any embodiment of the second aspect of the present invention, in the method for preparing the modified biochar catalyst, in step S2, the calcination temperature is 400-500℃, the calcination time is 4-5h, and the calcination atmosphere is air.

[0031] The third aspect of this invention discloses the application of the above-mentioned modified biochar catalyst, which is applied to the catalytic ozone oxidation degradation of complex heavy metal wastewater in complex water bodies, and at the same time, the recovery of heavy metals can be achieved.

[0032] The application of the modified biochar catalyst according to any embodiment of the third aspect of the present invention includes the steps of: adding the catalyst to complexed heavy metal wastewater, adjusting the pH to 5-8, preferably 6; adjusting the ozone concentration to 5-15 mg / L, preferably 8.7 mg / L, and carrying out degradation.

[0033] The selection of pH range is based on a comprehensive consideration of system stability and reaction efficiency. When the pH is below 5, the strong acidic environment inhibits the active oxygen pathway of ozone decomposition and accelerates the dissolution of active components, affecting the catalytic activity and stability of the catalyst. When the pH is above 8, the alkaline conditions will promote ozone self-decomposition, but will produce too much ·OH, reduce the selectivity of oxidation, and cause interfering precipitation.

[0034] The selection of ozone concentration range is based on the balance between oxidation efficiency and economy: when the concentration is below 5 mg / L, insufficient oxidant addition leads to slow reaction kinetics; when the concentration is above 15 mg / L, ineffective decomposition of ozone is likely to occur, and surface passivation may be triggered.

[0035] In the application of the modified biochar catalyst according to any embodiment of the third aspect of the present invention, the mass ratio of the catalyst added to the target heavy metal Cu in the wastewater is (0.2-0.6):1, preferably 5-15 mg / L.

[0036] In the application of the modified biochar catalyst according to any embodiment of the third aspect of the present invention, the pH is achieved by adding a pH adjuster, which may be one or more of sodium hydroxide and hydrochloric acid.

[0037] According to any embodiment of the third aspect of the present invention, the modified biochar catalyst is used in the case of complexed heavy metal wastewater containing complexed heavy metals and inorganic ions, wherein the heavy metals include one or more of Cu, Zn, Ni, and Co, the complexes include one or more of EDTA (ethylenediaminetetraacetic acid), citric acid, tartaric acid, and NAT (nitrotriacetic acid), and the inorganic ions include Cl... - CO3 2- and NO3 - One or more of the following. The method of the present invention can not only achieve the degradation of Cu complexes, but also be used for the degradation of heavy metal complexes such as Zn, Ni, and Co complexes.

[0038] This application uses a modified biochar catalyst containing cerium oxide to catalyze the ozone oxidation degradation of complex heavy metal wastewater in complex water bodies, especially Cu complexes.

[0039] The oxides of cerium include CeO. 2-x In the formula, x≥0.

[0040] In one feasible embodiment, the cerium oxide may include cerium dioxide (CeO2), cerium trioxide (Ce2O3), and non-stoichiometric cerium oxide (CeO2). 2-x ), which is a composite phase of various cerium oxides.

[0041] The aforementioned multivalent cerium and Cu in copper plating wastewater exhibit a synergistic effect: firstly, the reversible cycle of Ce(III) and Ce(IV) drives the dynamic generation of surface oxygen vacancies, thereby selectively catalyzing the conversion of ozone into singlet oxygen. 1 O2) enables efficient and precise disruption of Cu-complexes. Furthermore, the Cu released during disruption... 2+ Subsequently, a "Ce-O-Cu" interface structure is formed with the catalyst surface, in which Ce(III) acts as an electron donor to convert Cu... 2+ In-situ reduction to Cu + Simultaneously, Ce(III) is converted to Ce(IV), achieving chemical fixation and preliminary recovery of copper; the generated Ce(IV) can be rapidly regenerated, forming a coupled Ce-Cu bimetallic redox cycle. Ultimately, the in-situ formed Cu... + As a secondary catalytic center, it can efficiently activate ozone to generate free radicals such as ·OH, which react with Ce sites. 1 O2 forms a complementary synergistic oxidation network, which not only significantly enhances the system's resistance to and degradation of complex organic interferences (such as humic acid), but also achieves efficient recovery of heavy metals, deep removal of pollutants, and long-term stability of catalysts through a positive feedback cycle of "complex breaking-fixation-conversion-self-reinforcement".

[0042] In the reaction system, biochar (GAC) provides the reaction site, enriches reactants, and participates in electron transfer and the initial reduction of Cu; cerium-containing oxides act as catalytic centers, directionally converting O3 into a non-interfering form. 1 O2 initiates the complex-breaking reaction, and through Ce... 3+ / Ce 4+ Cyclic electron transfer is driven; O3: is both the initial oxidant and... 1 O2 precursor, and is converted by Cu + Secondary activation leads to synergy among oxide species; Cu ions transform from the target pollutant being treated into secondary catalytic active centers (Cu). + / Cu 2+ This not only accelerates the complete degradation of its own complexes, but also promotes the transformation and recycling of Cu species into stable solids, achieving waste treatment and self-recycling.

[0043] The presence and transformation of the target heavy metal Cu ions, through the formation of a stable interfacial structure with the active components of the catalyst and the construction of a synergistic catalytic network, not only realizes the resource recovery of Cu itself, but also effectively improves the catalyst's resistance to poisoning and cycle stability.

[0044] The modified biochar catalyst of this application exhibits higher catalytic efficiency, selectivity, stability, and anti-interference ability in the catalytic ozone oxidation degradation of complex heavy metal wastewater in complex water bodies.

[0045] Regarding catalytic efficiency: This stems from multivalent cerium (Ce) 3+ / Ce 4+ The rapid redox cycle of Ce and the synergistic effect of the Ce-Cu interface. 3+ / Ce 4+ The cycle drives ozone (O3) activation; during the reaction, Ce... 3+ Cu 2+ In-situ reduction to highly reactive Cu + Ce 3+ Converted to Ce 4+ The generated Cu + As a secondary catalytic center, it can efficiently activate O3 to generate free radicals such as ·OH, which react with Ce sites to produce 1 O2 forms a dual-center, multi-pathway synergistic oxidation network, while Cu is released during complex disruption. 2+ It forms a "Ce-O-Cu" interface structure with the CeO2 surface, chemically immobilizing the Ce component and improving the catalyst's stability; at the same time, Ce... 3+ / Ce 4 + The dynamic reversibility ensures the continuous and efficient generation of reactive oxygen species. Coconut shell charcoal has a well-developed conductive network, and its surface contains benzoquinone-hydroquinone redox pairs, which can serve as an efficient electron pool, continuously transferring electrons to Ce. 4+ Supply electrons to realize Ce 3+ Regeneration, through Ce 3+ / Ce 4+ The reversible cycle significantly improves the overall oxidation reaction rate and pollutant degradation efficiency of the system.

[0046] For selectivity: Utilizing cerium oxides, especially non-stoichiometric cerium oxides, which have abundant oxygen vacancies, it is possible to selectively convert O3 into singlet oxygen. 1 O2). 1 O2 is a highly selective reactive species that reacts through energy transfer or cycloaddition mechanisms. It exhibits high reactivity with target pollutants (such as specific functional groups in Cu-EDTA) but not with common inorganic ions in water (such as Cl-). - CO3 2- NO3 - The reaction is almost non-reactive. Therefore, even in the presence of a complex background matrix, the oxidation reaction preferentially targets the pollutant.

[0047] Regarding stability: During the reaction, the catalyst undergoes lattice strain, leading to its loss. The cubic fluorite structure of CeO2 can accommodate the lattice strain generated during cycling, ensuring that active sites are not lost or poisoned during long-term reactions. Simultaneously, Cu... 2+The Cu is firmly anchored to the catalyst framework via Ce-O-Cu bonds, effectively preventing the dissolution of active metal components. Furthermore, Cu... + / Cu 2+ With Ce 3+ / Ce 4+ The mutual support and functional complementarity of the two redox pairs ensure that even if the activity of one center decreases slightly, the other center can still maintain the function of the system, thereby ensuring the performance stability of the catalyst during long-term cyclic use.

[0048] Regarding anti-interference capabilities: primarily through... 1 The O2-dominated highly selective pathway and the Ce-Cu synergistic oxide network are achieved. First, 1 O2 quenches common inorganic ions (Cl-) - CO3 2- NO3 - It exhibits lower reactivity, avoiding quenching failure in the traditional ·OH pathway. Secondly, when complex organic compounds such as humic acid (HA) are present, the ·OH radicals generated by Ce-Cu synergy can effectively attack and mineralize these interfering substances, preventing them from accumulating on the catalyst surface and covering active sites. Simultaneously, Cu… + The formation of the center enhances the overall oxidation capacity of the system, ensuring that it maintains strong oxidation performance against target pollutants even in the presence of interfering substances, thus exhibiting excellent resistance to complex matrix interference.

[0049] Furthermore, this application is beneficial for Cu recovery: the modified biochar catalyst of this application exhibits a highly efficient and stable promoting effect on Cu recovery: firstly, the catalyst catalyzes the generation of highly selective singlet oxygen from ozone through the CeO2 active center ( 1 O2) precisely disrupts the organic ligands of stable complexes such as Cu-EDTA, achieving Cu 2+ The efficient release of Cu; subsequently, the released Cu 2 + It is rapidly enriched by the porous biochar support and firmly anchored to the catalyst framework by forming stable "Ce-O-Cu" chemical bonds with the CeO2 surface, completing the irreversible fixation from the liquid phase to the solid phase.

[0050] It should be noted that during the reduction of Cu(II), some Cu may also be generated in situ. 0 This further promotes the degradation of heavy metal complexes in the system, which is beneficial to improving the cyclic stability of the catalyst. Comparison of the full spectrum before and after the reaction reveals that extremely low levels of Cu are adsorbed on the catalyst after the reaction. Literature indicates that the peaks appearing at 934.0 eV and 932.5 eV can be attributed to Cu. 2+ and Cu 0This indicates that Cu is released during the degradation of Cu(II)-EDTA in the CeO2 / CSC catalytic ozone oxidation system. Under the catalysis of CeO2, Cu... 2+ It may be reduced to Cu 0 As active components, they work together to produce an effect.

[0051] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) A modified biochar catalyst of the present invention introduces cerium oxide. Cerium has a strong oxygen storage / release capacity, which is conducive to the generation of oxygen vacancies and regulates the directional generation of ozone into singlet oxygen. The two work together to show excellent selective catalytic ozone oxidation degradation of pollutants. (2) The modified biochar catalyst of the present invention is used in the treatment of complexed heavy metal wastewater. The catalyst and Cu in the wastewater work synergistically, resulting in higher catalytic efficiency, selectivity, stability and anti-interference ability. (3) The modified biochar catalyst of the present invention is used in the treatment of complexed heavy metal wastewater. Through the synergistic effect of the catalyst and Cu in the wastewater, it is beneficial to recover Cu. Attached Figure Description

[0052] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0053] Figure 1 (a) is a scanning electron microscope image of the biochar catalyst (GAC) from Example 1. Figure 1 (b) is a scanning electron microscope image of the modified biochar catalyst (CeO2@GAC) of Example 1; Figure 2 This is a Ce 3d XPS spectrum; Figure 3 This is a graph showing the total copper removal rate compared to different processes; Figure 4 These are the EPR experimental results for different catalyst systems. Detailed Implementation

[0054] The following detailed description of exemplary embodiments of the invention is taken with reference to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which the invention may be practiced. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from the spirit and scope thereof. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and not restrictive of the description of the features and characteristics of the invention, to suggest the best mode for carrying out the invention, and is sufficient to enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0055] The method for preparing the modified biochar catalyst according to embodiments of the present invention includes the following steps: S1. Impregnation: Dissolve the cerium source to obtain a cerium salt solution, add the bio-carbon source coconut shell carbon particles to the cerium salt solution, sonicate for 4 hours, let stand overnight, and then dry at 120°C; wherein, the cerium source is cerium nitrate hexahydrate, and the cerium nitrate hexahydrate solution is 0.1M. S2. Pyrolysis: Calcination at 500℃ for 4-5 hours yields modified biochar catalyst.

[0056] In the embodiments and comparative examples of the present invention, the degradation rate of Cu(II)-EDTA and the total Cu recovery rate are used as performance indicators of the catalyst.

[0057] The degradation rate of Cu(II)-EDTA and the total Cu recovery rate were used as performance evaluation indicators for the catalyst, and the specific calculations are as follows: (1) Cu(II)-EDTA degradation rate: During the reaction, samples were taken at specified time points, filtered through a filter membrane, and the reaction was terminated. The total copper concentration and the residual complexed copper concentration after masking were determined by atomic absorption spectrometry.

[0058] The degradation rate of Cu(II)-EDTA is calculated using the following formula: Degradation rate = (1 C complex,t / C complex,0 )×100%; Where C complex,0 With C complex,t , respectively, represent the initial and time t concentrations of the complexed copper state.

[0059] (2) Total Cu recovery rate: After the reaction is completed, the catalyst and the reaction solution are separated, and the total copper concentration in the filtrate is measured.

[0060] The total Cu recovery rate is calculated using the following formula: Recovery rate = (1 C final / C total,0 )×100%; Where C total,0 With C final These represent the total copper concentration in the solution at the initial stage and after the reaction is complete.

[0061] The coconut shell charcoal used in the embodiments and comparative examples of this invention was purchased from Pingdingshan Lvzhiyuan Activated Carbon Co., Ltd.: 1000 iodine value 4-8 mesh coconut shell / kg; the coconut shell charcoal meets the following requirements: specific surface area: 842.0030 m² 2 / g; Average pore size: 3.5920nm; Porosity: 0.3602cm³ 3 / g.

[0062] Example 1 This embodiment describes a method for preparing a modified biochar catalyst (CeO2@GAC), comprising the following steps: Step S1, Impregnation: Dissolve 5.21 g of Ce(NO3)3·6H2O in 120 ml of deionized water (Ce element molar concentration is 0.1 M). Impregnate 40 g of coconut shell charcoal particles in the above solution. Then, sonicate the resulting mixture in an ultrasonic bath for 4 hours, let it stand overnight, and dry it in a 120℃ oven for 24 hours. Do not add Cl. - and CO3 2- .

[0063] Step S2, pyrolysis: The mixture is placed in a muffle furnace and calcined at 500°C for 4 hours to obtain CeO2@GAC catalyst.

[0064] Electron micrograph of the prepared catalyst is shown below. Figure 1 As shown, Figure 1 (a) is a biochar catalyst (GAC). Figure 1 (b) is a scanning electron microscope (SEM) image of the cerium-modified biochar (CeO2@GAC) from Example 1. As can be seen from the image, the surface of the activated carbon particles before and after metal oxide loading is subjected to pitting erosion, resulting in a highly porous structure, which explains the large specific surface area of ​​the activated carbon. Aggregated microparticles are clearly visible on the surface of the activated carbon after metal oxide loading, some of which penetrate into the micropores, indicating that the impregnation method can successfully deposit metal oxides onto the activated carbon particles.

[0065] Figure 2 The Ce 3d XPS spectrum shows that Ce on the catalyst includes two valence states: one is Ce with characteristic peaks of V2 and U2. 3+ Secondly, the Ce characteristic peaks of V1, V3, V4, U1, U3, and U4. 4+ .

[0066] Comparative Example 1 This comparative example of a type of biochar (GAC) uses the same preparation method and carrier source as Example 1. The difference lies in that 40g of coconut shell char granules were placed directly into a muffle furnace without impregnation and calcined at 500°C in air for 4 hours. After cooling, pure GAC catalyst was obtained.

[0067] Example 2 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the concentration of the impregnation solution in step S1 is 0.05M.

[0068] Example 3 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the concentration of the impregnation solution in step S1 is 0.2M.

[0069] Example 4 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the concentration of the impregnation solution in step S1 is 0.3M.

[0070] Example 5 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the concentration of the impregnation solution in step S1 is 0.6M.

[0071] Example 6 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the impregnation time in step S1 is 2 hours.

[0072] Example 7 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the impregnation time in step S1 is 6 hours.

[0073] Example 8 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the impregnation time in step S1 is 8 hours.

[0074] Example 9 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the calcination temperature in step S2 is 300°C.

[0075] Example 10 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the calcination temperature in step S2 is 400°C.

[0076] Example 11 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the calcination temperature in step S2 is 600°C.

[0077] Example 12 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the calcination time in step S2 is 2 hours.

[0078] Example 13 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the calcination time in step S2 is 3 hours.

[0079] Example 14 The method for preparing a modified biochar catalyst (CeO2@GAC) in this embodiment differs from that in Example 1 in that the calcination time in step S2 is 5 hours.

[0080] Application Example 1 The degradation experiment was conducted in a stationary reactor at room temperature. 500 mL of an initial concentration of 0.4 mM Cu(II)-EDTA solution, 15 mg / L HA (humic acid) solution, and 5 g / L of the catalyst obtained in Example 1 were added to the reactor. The pH was adjusted to 6, and then 8 mg / L ozone was added to initiate the degradation reaction.

[0081] Intermittent sampling was performed, and the reaction solution was filtered using a 0.22 μm polyethersulfone needle filter. Sodium sulfite was added as a terminator, and the concentrations of Cu(II)-EDTA solution and total Cu were measured using atomic absorption spectrometry.

[0082] Application Example 2 The difference between this application example and Application Example 1 is that no HA solution is added.

[0083] Application Example 3 The difference between this application example and Application Example 1 is that the HA solution is 5 mg / L.

[0084] Application Example 4 The difference between this application example and Application Example 1 is that the HA solution is 10 mg / L.

[0085] Comparative Application Example 1 The difference between this comparative application example and application example 1 is that no catalyst or HA solution is added; only ozone is added.

[0086] Comparative Application Example 2 The difference between this comparative application example and application example 1 is that the catalyst is unmodified cerium biochar (GAC) and no ozone is added.

[0087] Comparative Application Example 3 The difference between this comparative application example and application example 1 is that the catalyst is unmodified cerium biochar (GAC), and only ozone is added.

[0088] Comparative Application Example 4 The difference between this comparative application example and application example 1 is that the catalyst is unmodified cerium biochar (GAC), with the addition of ozone and HA solution.

[0089] Degradation results are shown Figure 3 As can be seen from the figure, the degradation rate of Cu(II)-EDTA by the GAC+O3 and CeO2@GAC+O3 systems can reach 0.0492 min. -1 and 0.06889min -1 However, in the presence of HA, GAC exhibits poor interference resistance, with a degradation rate of only 0.01512 min. -1 However, CeO2@GAC remained undisturbed, with a degradation rate of 0.06847 min. -1 The reason is that CeO2 in CeO2@GAC reacts with Cu ions separated by complex breaking to form Ce-O-Cu bonds, thus enabling the recovery of Cu ions even in the presence of HA.

[0090] Figure 4 The EPR experiments of different systems can further confirm that the CeO2@GAC catalytic ozone oxidation process directionally produces singlet oxygen, which improves the catalyst's anti-interference ability in water bodies with multiple matrices.

[0091] It should be noted that the catalytic performance of pure biochar GAC decreases sharply in the presence of HA. On the one hand, HA competes with active species and target substances for active sites: HA has extremely strong adsorption properties and will irreversibly and strongly adsorb onto the surface and pores of GAC, resulting in the active sites of the catalyst being covered, preventing O3 and pollutants from contacting the catalytic center; and the catalyst pores are blocked, and the mass transfer resistance increases sharply. At this time, the porous structure of GAC becomes a site for HA adsorption in the presence of HA. On the other hand, HA competes with target pollutants for oxidants: In the GAC / O3 system, O3 may directly oxidize or weak free radicals (such as ·OH) may be oxidized on the surface of GAC. As a reducing organic compound, HA will strongly compete with target pollutants to consume these limited oxidants. Moreover, since the concentration of HA is usually much higher than that of target pollutants, and its molecular structure is diverse with a large number of sites that can react with oxidants, most of the oxidants are ineffectively consumed by HA, and the proportion of oxidants used to break the Cu-EDTA complex decreases significantly.

[0092] This application describes a CeO2@GAC catalyst system that releases Cu after complex disruption. 2+ The Ce-O-Cu interfacial bonds are formed with the catalyst surface, effectively enhancing its anti-interference ability. First, the formation of Ce-O-Cu bonds creates a Ce-Cu dual active center in situ for the catalyst. The existing Ce sites continue to catalyze the highly selective and quench-resistant production of ozone. 1 O2, while the newly fixed Cu sites are Cu + / Cu 2+ It exists in a form that can efficiently activate ozone to generate ·OH and other reactive oxygen species. These two reactive species form a complementary oxidation network: 1 O2 is responsible for selectively attacking specific structures of organic pollutants, such as the olefinic bonds of EDTA, while ·OH provides indiscriminate strong oxidizing properties. Even if complex organic compounds such as HA consume some ·OH, 1 The O2-dominated oxidation pathway remains unaffected, and the overall oxidation capacity is enhanced by the Cu produced during activation. + And significantly enhanced, with synergistic effects among the components.

[0093] Secondly, the Ce-O-Cu bond enables the functional transformation and self-cleaning of interfering substances: the fixed Cu species serve as catalytic sites, continuously activating O3 and in-situ oxidizing and degrading HA molecules adsorbed near the catalyst surface, preventing HA accumulation and covering of active sites, thus facilitating self-renewal of the catalyst surface. Simultaneously, the Ce-O-Cu bond, through strong chemical interaction, transfers Cu... 2+ Stable anchoring prevents the dissolution of active components and ensures long-term stability.

[0094] Application Example 5 The difference between this application example and application example 1 is that the modified biochar catalyst CeO2@GAC prepared in Examples 1-5 is added, and the concentration of the Cu(II)-EDTA solution is 4 mM.

[0095] The experiment was conducted according to the procedure of Application Example 1 to test the ability of modified biochar catalysts prepared with different impregnation solution concentrations to degrade Cu(II)-EDTA by ozone oxidation. Other conditions were the same as in Application Example 1. The measured Cu(II)-EDTA degradation rate and total Cu recovery rate are shown in Table 1.

[0096] Table 1. Degradation rate and total Cu recovery rate of Cu(II)-EDTA catalyzed by ozone oxidation of modified biochar catalysts prepared with different impregnation concentrations.

[0097] As shown in Table 1, the catalysts prepared using impregnation solutions with concentrations of 0.05M, 0.1M, 0.2M, 0.3M, and 0.6M catalyzed ozone oxidation within 30 minutes, degrading 78.1%, 100%, 100%, 95.8%, and 99.1% of Cu(II)-EDTA, respectively, and recovering 62.4%, 83.6%, 87.0%, 75%, and 79.5% of total copper, respectively. Considering both economy and efficiency, the 0.1M impregnation solution was the optimal choice.

[0098] Application Example 6 The difference between this application example and application example 1 is that the modified biochar catalyst CeO2@GAC prepared in Example 1 and Examples 6-8 is added, and the concentration of Cu(II)-EDTA solution is 4 mM.

[0099] The experiment was conducted according to the procedure of Application Example 1 to test the ability of modified biochar catalyst prepared with different impregnation times to degrade Cu(II)-EDTA by ozone oxidation. Other conditions were the same as in Application Example 1. The measured Cu(II)-EDTA degradation rate and total Cu recovery rate are shown in Table 2.

[0100] Table 2. Degradation rate and total Cu recovery rate of Cu(II)-EDTA catalyzed by ozone oxidation of modified biochar catalysts prepared with different impregnation times.

[0101] As shown in Table 2, the catalysts prepared with impregnation times of 2h, 4h, 6h and 8h catalyzed ozone oxidation within 30 minutes, respectively, degrading 94.3%, 95.5%, 97.8% and 100% of Cu(II)-EDTA, and recovering 65.5%, 62.4%, 83.6% and 83.6% of total copper, respectively. This indicates that the impregnation time has little effect on the catalyst activity.

[0102] Application Example 7 The difference between this application example and application example 1 is that the modified biochar catalyst (CeO2@GAC) prepared in Example 1 and Examples 9-11 is added, and the concentration of Cu(II)-EDTA solution is 4 mM.

[0103] The experiment was conducted according to the procedure of Application Example 1 to test the ability of modified biochar catalysts prepared at different calcination temperatures to degrade Cu(II)-EDTA by ozone oxidation. Other conditions were the same as in Application Example 1. The measured Cu(II)-EDTA degradation rate and total Cu recovery rate are shown in Table 3.

[0104] Table 3. Degradation rate and total Cu recovery rate of Cu(II)-EDTA catalyzed by ozone oxidation of modified biochar catalysts prepared at different calcination temperatures.

[0105] As shown in Table 3, the catalysts calcined at 300℃, 400℃, 500℃ and 600℃ degraded 94.3%, 98.8%, 100% and 80.4% of Cu(II)-EDTA by ozone oxidation within 30 minutes, respectively, and recovered 58.3%, 70.0%, 83.6% and 55.7% of total copper. Based on economic and efficiency considerations, the calcination temperature of 500℃ is the optimal one.

[0106] Application Example 8 The difference between this application example and application example 1 is that the modified biochar catalyst (CeO2@GAC) prepared in Example 1 and Examples 12-14 is added, and the concentration of Cu(II)-EDTA solution is 4 mM.

[0107] The experiment was conducted according to the procedure of Application Example 1 to test the ability of modified biochar catalysts prepared with different calcination times to degrade Cu(II)-EDTA by ozone oxidation. Other conditions were the same as in Application Example 1. The measured Cu(II)-EDTA degradation rate and total Cu recovery rate are shown in Table 4.

[0108] Table 4. Degradation rate and total Cu recovery rate of Cu(II)-EDTA catalyzed by ozone oxidation of modified biochar catalysts prepared with different calcination times.

[0109] As shown in Table 4, the catalysts calcined for 2h, 3h, 4h and 5h catalyzed ozone oxidation within 30 minutes, respectively, degrading 98.3%, 97.6%, 100% and 70.6% of Cu(II)-EDTA, and recovering 71.2%, 66.5%, 83.6% and 64.6% of total copper. Considering both economy and efficiency, calcination for 4h was optimal.

[0110] Application Example 9 The difference between this application example and Application Example 1 is that different concentrations of Cl are added. - .

[0111] Following the procedure in Application Example 1, experiments were conducted to test the CeO2@GAC catalyst at different concentrations of Cl. - The degradation rate of Cu(II)-EDTA and the total Cu recovery rate in the system were the same as in Application Example 1, under the same conditions. Table 5 shows that Cl... - As a common interfering ion in wastewater systems, its addition not only did not hinder the catalytic process, but also promoted the degradation of Cu(II)-EDTA and the recovery of Cu. This is because Cl... - It can react with ozone, indirectly promoting the generation of active species and accelerating degradation reactions.

[0112] Although Cl - right 1 O2 has almost no quenching effect, but it can react with residual ozone molecules in the system or trace amounts of ·OH generated by secondary pathways to generate a series of reactive chloride species (RCS), such as hypochlorous acid / hypochlorite (HOCl / ClO). - ), chlorine radicals (Cl·), etc. These RCS, especially HOCl (E), 0 = 1.48 V), it is an oxidizing agent with moderate oxidation potential and good selectivity. 1 In an O2-dominated system, HOCl and 1 O2 synergistic oxidation: among which 1 O2 is adept at attacking C=C double bonds and electron-rich aromatic rings in organic compounds, disrupting the organic framework of complexing agents such as EDTA; HOCl exhibits specific electrophilic attack capabilities on nitrogen- and sulfur-containing functional groups, such as the amine groups in EDTA. Therefore, Cl - The existence of this led to the generation of RCS, and 1 O2 synergistically attacks heavy metal complexes from different reaction sites, accelerating complex disruption. As shown in Table 5, in Cl... - In the presence of Cu(II)-EDTA, the degradation rate and the total copper recovery rate are simultaneously improved.

[0113] Table 5. Different concentrations of Cl - Effects on the degradation rate of Cu(II)-EDTA and the total Cu recovery rate

[0114] Application Example 10 The difference between this application example and Application Example 1 is that different concentrations of CO3 are added. 2- .

[0115] Following the procedure in Application Example 1, experiments were conducted to test the CeO2@GAC catalyst at different CO3 concentrations. 2- The degradation rate of Cu(II)-EDTA and the total Cu recovery rate were compared under the same conditions as in Application Example 1. Table 6 shows that low concentrations of CO3... 2- (10 mM) promotes the reaction, and high concentrations of CO32- have a promoting effect. 2- (100 mM) had a slight inhibitory effect on the reaction, which may be due to the fact that at lower concentrations, CO3... 2- It can react with ozone, indirectly promoting the generation of reactive species and accelerating the degradation of organic matter; but CO3... 2- It is a basic ion that can adjust the pH of a solution to make it closer to neutral or weakly alkaline, while ozone is more likely to decompose into ·OH under alkaline conditions.

[0116] CO3 2- / HCO3 - It forms a natural buffer system, stabilizing the pH of the reaction solution within a weakly alkaline range (7.5-9.0). Within this pH range, the self-decomposition rate of ozone accelerates, promoting the generation of reactive species; a suitable pH helps maintain the hydroxylation state and electronic structure of the CeO2 surface, promoting oxygen vacancy formation and ozone adsorption activation; furthermore, low concentrations of CO3... 2- It can react with trace amounts of ·OH in the system to generate carbonate free radicals (CO3· · OH). - CO3· - Although its oxidation potential (~1.78 V) is lower than that of ·OH, it has a longer lifespan and higher selectivity, especially for nitrogen-, sulfur-, and phenolic organic compounds.

[0117] And when CO3 2- When the concentration is too high (e.g., 100 mM), high concentrations of CO3 2- It will react significantly with ozone molecules, consuming the ozone that it is a raw material for; excessive CO3 2- Ozone strongly adsorbs on the catalyst surface, competing for or covering some active sites, hindering contact between ozone and the catalyst, and limiting mass transfer.

[0118] Table 6 CeO2@GAC catalyst at different CO3 concentrations 2- Degradation rate of Cu(II)-EDTA and total Cu recovery rate

[0119] Application Example 11 The difference between this application example and Application Example 1 is that different concentrations of NO3 are added. - Following the procedure in Application Example 1, experiments were conducted to test the CeO2@GAC catalyst at different concentrations of NO3.- The degradation rate of Cu(II)-EDTA and the total Cu recovery rate were compared under the same conditions as in Application Example 1. Table 7 shows that NO3... - The catalytic system exhibits virtually no inhibitory or promoting effect on the degradation of Cu(II)-EDTA and the recovery of Cu. 1 O2 is the main active species. Since the quenching effect of the oxidant is mainly against ·OH, the quenching effect of the oxidant in this catalytic system is negligible and has little effect on the reaction process.

[0120] Table 7 CeO2@GAC catalyst at different NO3 concentrations - Degradation rate of Cu(II)-EDTA and total Cu recovery rate

[0121] Application Example 12 The difference between this application example and application example 1 is that different concentrations of HA are added.

[0122] The experiment was conducted following the procedure of Application Example 1, testing the degradation rate of Cu(II)-EDTA and the total Cu recovery rate of the CeO2@GAC catalyst at different concentrations of HA, with other conditions remaining the same as in Application Example 1. Table 8 shows that HA has virtually no inhibitory or promoting effect on the degradation of Cu(II)-EDTA and the recovery of Cu, indicating that the CeO2@GAC catalyst of this application can maintain high catalytic performance and high selectivity even in the presence of HA.

[0123] Table 8. Degradation rate of Cu(II)-EDTA and total Cu recovery rate of CeO2@GAC catalyst at different concentrations of HA

[0124] HA exhibits significantly lower reactivity to ¹O₂ than to ·OH. Although HA still consumes some oxidant, its high selectivity for ¹O₂ enhances its competitiveness in reacting with the target pollutant. Furthermore, the macroscopic structure of the bulk biochar support is more resistant to surface covering and pore blockage caused by HA compared to powdered catalysts, ensuring the long-term activity and stability of the catalyst.

[0125] Compared to pure O3, the CeO2@GAC+O3 system can achieve a recovery rate of 0.06889 min for the total Cu in the system. -1 And in CO3 2- Cl - NO3 - Even in the presence of HA, the catalytic performance of CeO2@GAC remains undisturbed, with recovery rates still reaching 0.07576 min. -10.08322min -1 0.07238 and 0.06847 min -1 The reason is that the cubic fluorite structure of CeO2 in CeO2@GAC allows ozone oxidation to be directly decomposed into singlet oxygen, improving the system's selectivity and anti-interference ability. Furthermore, the catalyst reacts with the Cu ions separated by complex breaking to form Ce-O-Cu bonds, enabling the recovery of Cu ions even in the presence of complex ions.

[0126] Traditional ozone catalytic oxidation technology relies on catalysts to activate ozone and generate hydroxyl radicals (·OH, E) with high oxidation potential. 0 = 2.8 V). However, ·OH is a non-selective strong oxidizing agent and reacts with inorganic anions (such as Cl-) that are widely present in aqueous matrices. - CO3 2- / HCO3 - NO3 - The oxidation efficiency is severely reduced due to the violent quenching reaction of soluble organic matter (such as HA).

[0127] The catalyst of this invention supports cubic fluorite-structured cerium dioxide on porous biochar, utilizing the abundant surface oxygen vacancies in CeO2 and reversible Ce... 3+ / Ce 4+ Redox pairs can efficiently catalyze the decomposition of ozone, preferentially generating singlet oxygen. 1 O2 is the main reactive oxygen species. 1 O2 primarily reacts with electron-rich organic compounds through mechanisms such as energy transfer or cycloaddition. Its reaction rate constant (k) with the aforementioned inorganic anions is extremely low, typically several orders of magnitude lower than its reaction with ·OH. Therefore, when the dominant active species in the reaction system changes from ·OH to… 1 When O2 is present, traditional quenchers lose their main target and their interference effect is fundamentally suppressed.

[0128] Application Example 13 The cerium-modified biochar (CeO2@GAC) prepared in Example 1 was used in a catalytic ozone oxidation degradation of Cu(II)-EDTA wastewater in a recycling experiment. A 0.4 mM Cu(II)-EDTA solution and a 15 mg / L HA solution were prepared in a fixed reactor at room temperature. After adjusting the pH to 6, the modified biochar catalyst CeO2@GAC and ozone at a concentration of 8.7 mg / L were added to initiate the degradation reaction. The reaction was allowed to proceed for 1 hour. The catalyst was then removed, dried, and used for a second round of experiments, repeated five times. After five cycles, the total copper removal rate still reached 91.4%.

[0129] Application Example 14 This application example uses the cerium-modified biochar catalyst (CeO2@GAC) prepared in Example 1 to treat the effluent from an actual electroplating industrial park workshop, in order to verify its adaptability, stability and comprehensive treatment effect on complex actual wastewater under continuous flow conditions.

[0130] [Wastewater Sources and Water Quality] The wastewater was taken from the effluent outlet of a workshop in an electroplating industrial park in Wenzhou. Its main water quality parameters are shown in Table 9.

[0131] Table 9 Actual water quality parameters of electroplating wastewater

[0132] [Continuous Flow Experiment] A continuous flow reactor was used, with a designed hydraulic retention time (HRT) of 60 min, an ozone concentration of 8.7 mg / L, a single catalyst dosage of 50 g, corresponding to an effective reactor volume of 5 L, a catalyst concentration of 10 g / L, and influent and effluent flow rates controlled at 0.008 L / min. The experiment ran continuously for 24 h, with effluent water quality samples taken every 1 h for testing.

[0133] After the system has been running stably, the removal efficiency of each pollutant is shown in Table 10: Table 10 Actual Pollutant Removal Effect in Electroplating Wastewater

[0134] The catalyst of this application has a good removal effect on pollutants in actual electroplating wastewater, especially complexed Cu, with a removal rate of >99%.

[0135] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0136] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A modified biochar catalyst, characterized in that, include: Carrier: Biochar, which has a porous structure; Active component: Oxides containing cerium supported on a carrier; The oxides of cerium include cerium dioxide, cerium trioxide, and cerium oxide in non-stoichiometric proportions; The loading amount of the active component on the carrier is 1 wt% to 10 wt%.

2. The modified biochar catalyst according to claim 1, characterized in that, The cerium dioxide has a cubic fluorite structure.

3. The modified biochar catalyst according to claim 1, characterized in that, The non-stoichiometric cerium oxide exists in the surface, grain boundaries, and defects of cerium dioxide; The cerium trioxide exists in non-stoichiometric cerium oxide and cerium dioxide surface active sites.

4. The modified biochar catalyst according to claim 1, characterized in that, The carrier is biochar, including one or more of coconut shell charcoal, walnut shell charcoal, and apricot kernel charcoal; and / or, The carrier has an average pore size of 3-5 nm and a porosity of 0.25-0.6 cm. 3 / g.

5. A method for preparing the modified biochar catalyst according to any one of claims 1-4, characterized in that, Includes the following steps: Step S1, Impregnation: Dissolve the cerium source to obtain a cerium salt solution, add the bio-carbon source to the cerium salt solution, sonicate for several hours, let stand overnight, and then dry. Step S2, pyrolysis: calcination treatment to obtain modified biochar catalyst.

6. The method for preparing the modified biochar catalyst according to claim 5, characterized in that, In step S1, The cerium source includes one or more of cerium nitrate, cerium chloride, cerium sulfate, cerium ammonium nitrate, and cerium carbonate; and / or, The concentration of the cerium salt solution is 0.1-0.15 M; and / or, The ultrasonic treatment time is 4-5 hours, and the drying temperature is 120-130℃.

7. The method for preparing the modified biochar catalyst according to claim 6, characterized in that, In step S2, the calcination temperature is 400-500℃, the calcination time is 4-5h, and the calcination atmosphere is air.

8. The application of the modified biochar catalyst according to any one of claims 1-4, characterized in that, Modified biochar catalysts were used to catalyze the ozone oxidation and degradation of complex heavy metal wastewater in complex water bodies.

9. The application of the modified biochar catalyst according to claim 8, characterized in that, The steps include: adding the catalyst to the complexed heavy metal wastewater, adjusting the pH to 5-8, adjusting the ozone concentration to 5-15 mg / L, and then carrying out degradation.

10. The application of the modified biochar catalyst according to claim 8, characterized in that, The complexed heavy metal wastewater contains heavy metal complexes and inorganic ions. The heavy metals include one or more of Cu, Zn, Ni, and Co. The complexes include one or more of ethylenediaminetetraacetic acid, citric acid, tartaric acid, and triacetic acid. The inorganic ions include Cl. - CO3 2- and NO3 - One or more of them.

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