Aluminum-cobalt bimetallic ionic liquid modified biochar catalyst, and preparation method and application thereof

Abstract

This invention discloses an aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst, its preparation method, and its application, belonging to the technical field of water pollution control and environmental functional materials. The method involves mixing an aluminum-cobalt bimetallic ionic liquid with biomass raw materials, followed by one-step or two-step pyrolysis, then cooling, washing, and drying to obtain the aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst. This method eliminates the need for prior preparation of a biochar precursor followed by secondary loading, enabling simultaneous pore formation, nitrogen doping, aluminum-cobalt bimetallic active site construction, and metal-oxygen coordination structure formation of biochar in a single pyrolysis process. The process is simple, and the raw materials are readily available. The resulting catalyst possesses a high specific surface area, abundant surface defects, and stable aluminum-cobalt synergistic active sites, enabling efficient activation of persulfate and rapid degradation of norfloxacin under near-neutral conditions. It also exhibits good anti-interference properties, cycle stability, and potential for practical water body application.

Description

Technical Field

[0001] This invention belongs to the technical field of water pollution control and environmental functional materials, and particularly relates to an aluminum-cobalt bimetallic ion liquid modified biochar catalyst, its preparation method and application. Background Technology

[0002] Antibiotics (especially fluoroquinolone antibiotics) are widely used in medical, aquaculture, and pharmaceutical fields, and their continuous input into the environment has become a typical emerging pollutant problem. Norfloxacin, as a common fluoroquinolone antibiotic, is characterized by its stable molecular structure, strong environmental persistence, and high potential ecotoxicity. Once it enters water bodies, it is not easily removed completely by conventional biological methods, and there is an urgent need to develop efficient and stable deep purification technologies.

[0003] Currently, adsorption, membrane separation, biodegradation, and advanced oxidation methods can all be used for antibiotic wastewater treatment. Among them, persulfate-based advanced oxidation technology has attracted widespread attention due to its advantages such as strong oxidizing power, wide applicable pH range, and excellent removal effect on recalcitrant organic pollutants. However, persulfate (PDS) itself has limited reactivity and usually requires the assistance of catalysts to activate it and generate reactive species such as sulfate radicals, hydroxyl radicals, and singlet oxygen to achieve rapid degradation of the target pollutants.

[0004] Biochar is considered a promising persulfate activation support material due to its wide availability, low cost, and highly tunable surface properties. However, unmodified biochar typically suffers from low specific surface area, insufficient defect sites, limited active sites, and weak electron transport capabilities, resulting in limited catalytic activity. To improve the persulfate activation performance of biochar, researchers often modify it by introducing transition metals or heteroatoms. However, traditional methods often employ multi-step processes such as "metal salt impregnation + high-temperature carbonization" or "char preparation followed by loading," which are not only cumbersome but also leave room for improvement in metal dispersion and structural stability. Furthermore, in traditional metal salt impregnation or post-loading modification methods, the metal components often exist on the biochar surface in the form of physical loading or simple deposition, resulting in limited dispersion and binding stability of active sites. Consequently, problems such as metal loss, insufficient structural stability, and restricted interfacial electron migration may occur.

[0005] Therefore, developing a novel biochar catalyst is of great significance for improving the activation efficiency of persulfate and achieving efficient degradation of norfloxacin. Summary of the Invention

[0006] To address the problems of complex preparation processes, insufficient metal site stability, and limited removal efficiency for recalcitrant fluoroquinolone antibiotics in existing biochar catalysts, this invention proposes an aluminum-cobalt bimetallic ionic liquid modified biochar catalyst, its preparation method, and its application. The aluminum-cobalt bimetallic ionic liquid modified biochar catalyst of this invention can activate persulfate to degrade quinolone antibiotics (especially norfloxacin).

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing an aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst, comprising the following steps: One-step pyrolysis: The aluminum-cobalt bimetallic ionic liquid is mixed with biomass raw material and preheated to allow the aluminum-cobalt bimetallic ionic liquid to fully wet the biomass raw material; the preheated mixture is subjected to high-temperature pyrolysis under an inert atmosphere, cooled, washed and dried to obtain the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst. Alternatively, a two-step pyrolysis method is used: the biomass raw material is pyrolyzed at a low temperature of 400~600℃ to obtain a biochar precursor; the biochar precursor is mixed with an aluminum-cobalt bimetallic ionic liquid and pyrolyzed at a high temperature of 700~900℃ to obtain the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst.

[0008] Cobalt is the main active metal component for activating PDS and promoting the oxidative degradation of norfloxacin, and can promote PDS activation and induce the generation of various reactive oxygen species. Aluminum itself is not a typical reversible variable-valence transition metal and is generally not considered to be a major active center for persulfate activation. This invention introduces aluminum as an auxiliary regulating component into a cobalt-based biochar system, constructing a synergistic aluminum-cobalt active interface through one-step pyrolysis of aluminum-cobalt bimetallic ionic liquid, improving the dispersion and immobilization state of cobalt, regulating the electronic structure of the catalyst surface, thereby enhancing PDS activation efficiency and interfacial electron transfer capacity. Unlike existing technologies that rely on Fe / Co dual transition metal redox cycles to activate persulfate, the material prepared by this invention exhibits excellent norfloxacin degradation efficiency and low Co leaching concentration, achieving the technical effects of enhanced PDS activation, improved electron transfer efficiency, and reduced metal leaching risk. The method of this invention can simultaneously achieve biochar pore formation, nitrogen doping, aluminum-cobalt synergistic active site construction and metal-oxygen coordination structure formation in a single pyrolysis process. The resulting catalyst can efficiently activate PDS and rapidly degrade norfloxacin under near-neutral conditions, and has good anti-interference, cycle stability and potential for practical water application.

[0009] Furthermore, the preparation process of the aluminum-cobalt bimetallic ionic liquid is as follows: first, the imidazole ionic liquid is melted at 70~100 °C, a soluble aluminum salt is added and reacted at 100~130 °C for 1~4 h, then a soluble cobalt salt is added and reacted at 130~170 °C for 8~16 h, and the aluminum-cobalt bimetallic ionic liquid is obtained after cooling.

[0010] Furthermore, the imidazole ionic liquid is 1-ethyl-3-methylimidazolium chloride, the soluble aluminum salt is aluminum chloride, and the soluble cobalt salt is cobalt chloride.

[0011] Further, the molar ratio of 1-ethyl-3-methylimidazolium chloride, aluminum chloride and cobalt chloride is 1:(0.3~0.6):(0.3~0.6).

[0012] Furthermore, the mass ratio of the aluminum-cobalt bimetallic ionic liquid to the biomass raw material is 2:1.

[0013] Furthermore, the preheating temperature is 150 °C, and the time is 6~12 h.

[0014] Furthermore, the high-temperature pyrolysis under an inert atmosphere was carried out at a temperature of 800 °C, a holding time of 2 h, and a heating rate of 5 °C / min.

[0015] Furthermore, the low-temperature pyrolysis at 400~600℃ takes 1~3 h with a heating rate of 3~10 ℃ / min; the high-temperature pyrolysis at 700~900℃ takes 2 h with a heating rate of 5 ℃ / min; both low-temperature and high-temperature pyrolysis are carried out under an inert atmosphere.

[0016] The present invention also provides an aluminum-cobalt bimetallic ionic liquid modified biochar catalyst prepared according to the above preparation method.

[0017] The present invention also provides an application of the above-mentioned aluminum-cobalt bimetallic ionic liquid modified biochar catalyst in the degradation of organic pollutants by activated persulfate, wherein the organic pollutants are quinolone antibiotics.

[0018] Furthermore, the dosage of the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst is 0.05~0.20 g / L, and the persulfate concentration is 0.1~2.0 mM.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The present invention uses aluminum-cobalt bimetallic ionic liquid as a single modification source to achieve pore formation, heteroatom doping and bimetallic active site construction of biochar through one-step pyrolysis or two-step pyrolysis; in particular, pore formation, heteroatom doping and bimetallic active site construction of biochar can be achieved simultaneously through one-step pyrolysis, without the need to prepare biochar precursor first and then perform secondary loading, which significantly simplifies the process.

[0020] (2) The catalyst obtained by the present invention has a high specific surface area, abundant surface defects, stable metal oxygen coordination structure and aluminum-cobalt synergistic active sites, and has excellent activation ability for persulfate, and can efficiently degrade recalcitrant antibiotic pollutants such as norfloxacin.

[0021] (3) The catalyst obtained in this invention exhibits excellent catalytic performance under neutral to weakly acidic conditions and maintains high removal efficiency in most common anions, natural organic matter and actual water environments, indicating that it has good environmental adaptability.

[0022] (4) The catalyst obtained by the present invention has good cycle stability and low metal leaching risk, and has practical application potential. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A comparison of the degradation performance of norfloxacin by Al / Co-0.5-PBC obtained by one-step pyrolysis and Al / Co-0.5-T-PBC obtained by two-step pyrolysis is shown in the figure. Figure 2 (a) shows the degradation performance of catalysts obtained from different aluminum-cobalt bimetallic ionic liquids on norfloxacin, and (b) shows the removal effect of catalysts on norfloxacin in the absence of PDS. Figure 3 A comparison of the degradation performance of norfloxacin by Co-PBC and Al / Co-0.5-PBC; Figure 4 The images are SEM and HR-TEM images of the materials, where a is the SEM image of UPBC, b is the SEM image of Al / Co-0.5-PBC, c is the SEM image of Co-PBC, d is the HR-TEM image of Al / Co-0.5-PBC, and e is the HR-TEM image of Co-PBC. Figure 5 XRD and Raman spectra of UPBC, Co-PBC and Al / Co-0.5-PBC are shown, where (a) is the XRD spectrum and (b) is the Raman spectrum. Figure 6The FT-IR and XPS full spectra of UPBC, Co-PBC and Al / Co-0.5-PBC are shown, where (a) is the FT-IR spectrum and (b) is the XPS full spectrum. Figure 7 The high-resolution O 1s and Co 2p spectra of UPBC, Co-PBC and Al / Co-0.5-PBC are shown, where (a) is the high-resolution O 1s spectrum of UPBC, Co-PBC and Al / Co-0.5-PBC, and (b) is the high-resolution Co 2p spectrum of Co-PBC and Al / Co-0.5-PBC. Figure 8 The graph shows the effects of pH (a) and coexisting anions and humic acid (b) on the degradation of norfloxacin in the Al / Co-0.5-PBC / PDS system. Figure 9 Figure (a) shows the experimental results of repeated use of Al / Co-0.5-PBC, and Figure (b) shows the Co leaching concentration during the cycle. Figure 10 The image shows the application effect of Al / Co-0.5-PBC in actual water samples (deionized water, tap water, river water); Figure 11 Figure (a) shows the quenching experiment of norfloxacin and the DMPO-·OH / SO4 ratio. ·- (b) DMPO-O2 ·- (c) and TEMP- 1 EPR spectrum of O2(d); Figure 12 The images show the EPR spectra of active species in the Al / Co-0.5-PBC / PDS and Co-PBC / PDS systems, where (a) represents DMPO-·OH / SO4. ·- (b) is DMPO-O2 ·- (c) is TEMP- 1 O2; Figure 13 Nyquist plot (a), it curve (b), and LSV curve (c) for Co-PBC and Al / Co-0.5-PBC, respectively. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] An embodiment of the present invention provides a method for preparing an aluminum-cobalt bimetallic ionic liquid modified biochar catalyst, comprising the following steps: One-step pyrolysis: Aluminum-cobalt bimetallic ionic liquid is mixed with biomass raw material and preheated to allow the aluminum-cobalt bimetallic ionic liquid to fully wet the biomass raw material; the preheated mixture is subjected to high-temperature pyrolysis under an inert atmosphere, cooled, washed and dried to obtain aluminum-cobalt bimetallic ionic liquid modified biochar catalyst. Alternatively, a two-step pyrolysis method can be used: the biomass feedstock is pyrolyzed at a low temperature of 400~600℃ to obtain a biochar precursor; the biochar precursor is mixed with an aluminum-cobalt bimetallic ionic liquid and pyrolyzed at a high temperature of 700~900℃ to obtain an aluminum-cobalt bimetallic ionic liquid modified biochar catalyst.

[0030] For example, the biomass raw material is poplar wood powder.

[0031] In a preferred embodiment of the present invention, the preparation process of the aluminum-cobalt bimetallic ionic liquid is as follows: first, an imidazole ionic liquid is melted at 70-100 °C, a soluble aluminum salt is added and reacted at 100-130 °C for 1-4 h, then a soluble cobalt salt is added and reacted at 130-170 °C for 8-16 h, and after cooling, the aluminum-cobalt bimetallic ionic liquid is obtained; preferably, the preparation process of the aluminum-cobalt bimetallic ionic liquid is as follows: first, an imidazole ionic liquid is melted at 80 °C, a soluble aluminum salt is added and reacted at 120 °C for 2 h, then a soluble cobalt salt is added and reacted at 150 °C for 12 h, and after cooling, the aluminum-cobalt bimetallic ionic liquid is obtained.

[0032] In a preferred embodiment of the present invention, the imidazole ionic liquid is 1-ethyl-3-methylimidazolium chloride, the soluble aluminum salt is aluminum chloride, and the soluble cobalt salt is cobalt chloride.

[0033] In a preferred embodiment of the present invention, the molar ratio of 1-ethyl-3-methylimidazolium chloride, aluminum chloride and cobalt chloride is 1:(0.3~0.6):(0.3~0.6).

[0034] In a preferred embodiment of the present invention, the mass ratio of aluminum-cobalt bimetallic ionic liquid to biomass raw material is 2:1.

[0035] In a preferred embodiment of the present invention, the preheating temperature is 150 °C and the time is 12 h.

[0036] In a preferred embodiment of the present invention, the temperature for high-temperature pyrolysis under an inert atmosphere is 800 °C, the holding time is 2 h, and the heating rate is 5 °C / min.

[0037] In a preferred embodiment of the present invention, the two-step pyrolysis preparation of aluminum-cobalt bimetallic ionic liquid modified biochar catalyst is carried out under a nitrogen atmosphere. The low-temperature pyrolysis at 400~600℃ takes 1~3 h with a heating rate of 3~10℃ / min; the high-temperature pyrolysis at 800℃ takes 2 h with a heating rate of 5℃ / min.

[0038] For example, the inert atmosphere is a nitrogen atmosphere.

[0039] An embodiment of the present invention also provides an aluminum-cobalt bimetallic ionic liquid modified biochar catalyst prepared according to the above preparation method.

[0040] An embodiment of the present invention also provides the application of the above-mentioned aluminum-cobalt bimetallic ionic liquid modified biochar catalyst in the degradation of organic pollutants by activated persulfate, wherein the organic pollutant is a quinolone antibiotic, preferably norfloxacin.

[0041] In a preferred embodiment of the present invention, the pH of the quinolone antibiotic solution is 3.0 to 11.0, the dosage of the aluminum-cobalt bimetallic ion liquid modified biochar catalyst is 0.05 to 0.20 g / L, and the concentration of persulfate is 0.1 to 2.0 mM.

[0042] In a preferred embodiment of the present invention, when using an aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst to activate persulfate for the degradation of norfloxacin, the pH of the norfloxacin-containing solution is 3.0–11.0 (preferably 3.0–7.0), the dosage of the aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst is 0.05–0.20 g / L, the persulfate concentration is 0.1–2.0 mM, and the initial concentration of norfloxacin is 1–50 mg / L. When the catalyst dosage is 0.10 g / L, the persulfate concentration is 0.5 mM, and the initial concentration of norfloxacin is 10 mg / L, the aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst can achieve efficient degradation of norfloxacin within 60 min.

[0043] The reason why the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst of this invention (taking Al / Co-0.5-PBC as an example) can efficiently activate persulfate (PDS) and rapidly degrade norfloxacin lies in the "free radical-non-free radical synergistic catalytic mechanism" endowed by its unique material structure and chemical composition. Specifically, this can be summarized into the following four levels of synergistic effects: 1. Electron synergy and structural stabilization effects of aluminum-cobalt bimetals Formation of a spinel-type CoAl2O4 active phase: HR-TEM and XRD results confirm that the aluminum-cobalt bimetallic ionic liquid preferentially forms a highly stable spinel-type CoAl2O4 structure (corresponding to crystal planes (200), (311), etc.) during pyrolysis, rather than the Co3O4 or CoO that are easily formed in a single cobalt-based system. This structure has the following advantages: Electronic control: Al 3+ Introducing the Co-O lattice alters the coordination environment of Co and optimizes its electronic distribution (XPS analysis shows that the 2p peak of Co in Al / Co-0.5-PBC is consistent with the characteristics of CoAl2O4). This aluminum-cobalt synergistic structure promotes the adsorption and activation of PDS on the catalyst surface and interfacial electron transfer, thereby improving the PDS activation efficiency.

[0044] Site isolation and stability: Al 3+ As an inert framework ion, it helps improve the immobilization state and dispersion stability of Co species, preventing the aggregation of Co atoms and their loss during redox cycles. Experiments have shown that after five cycles of Al / Co-0.5-PBC, the Co leaching concentration is only 0.09~0.18 mg / L, which is much lower than that of single Co-PBC (0.89 mg / L).

[0045] 2. The contribution of high specific surface area and abundant defects to mass transfer and active sites Porous structure accelerates mass transfer: In the one-step pyrolysis process, the aluminum-cobalt bimetallic ionic liquid simultaneously acts as a pore-forming agent and an activator. The resulting catalyst has a specific surface area as high as 178.47 m². 2 / g (far higher than the 62.33 m of unmodified UPBC) 2 / g), forming a rich micro / mesoporous structure (average pore size 2.59 nm). This structure increases the probability of contact between the catalyst and PDS and norfloxacin molecules, and shortens the contact time between active species (such as SO4). ·- The diffusion distance from the generation site to the target pollutant.

[0046] The highly defective carbon framework promotes electron transfer: Raman spectroscopy shows that the ID / IG value of Al / Co-0.5-PBC reaches 3.27 (higher than 2.75 for Co-PBC), indicating that its carbon framework contains a large number of intrinsic defects (such as edge sites, vacancies, and dangling bonds). These defect sites themselves can serve as adsorption and activation centers for PDS, and together with the conductive carbon framework, promote the non-radical electron transfer process.

[0047] 3. Cooperative activation pathways of free radicals and non-free radicals Through quenching experiments, EPR, and electrochemical tests, this invention clarifies that both free radical and non-free radical pathways exist simultaneously in the system, and their synergistic effect significantly improves degradation efficiency. Free radical pathway (dominant): PDS is activated by the Co(II) / Co(III) redox pair in CoAl2O4, and cleaves to produce SO4. ·- (Standard redox potential 2.5~3.1 V) and ·OH. EPR detected strong DMPO-·OH / SO4. ·- Additive signal, quenching experiment shows SO4 ·- The ·OH radicals contribute the most. These free radicals can efficiently attack the electron-rich structures of norfloxacin, such as the piperazine ring and quinolone ring, to achieve ring-opening mineralization.

[0048] Non-radical pathway (synergistic enhancement): Surface-mediated electron transfer: Electrochemical tests show that Al / Co-0.5-PBC has a smaller charge transfer resistance and a stronger PDS-induced current response (it curve), indicating that after PDS is adsorbed on the catalyst surface (especially defect sites and Co sites), it can directly transfer electrons to the adsorbed norfloxacin molecules through the catalyst carbon matrix, bypassing the free radical intermediate.

[0049] Singlet oxygen ( 1 O2) generation: EPR detects TEMP- 1The characteristic signal of O2 indicates the presence of non-radical components in the system. 1 O2 oxidation pathway (from O2) ·- Disproportionation or direct decomposition of PDS). 1 O2 has the ability to selectively oxidize electron-rich organic pollutants.

[0050] Compared to Co-PBC, Al / Co-0.5-PBC has all active species (SO4) ·- ·OH, O2 ·- , 1 The EPR signals of O2 were stronger, confirming the promoting effect of bimetallic synergy on multiple activation pathways.

[0051] 4. The auxiliary regulatory role of aluminum: reducing metal leaching and widening the pH adaptation range. Inhibition of Co leaching: The stability of the Al-O bond in the CoAl2O4 structure significantly reduces the leaching of Co in the reaction medium, ensuring the cyclic stability of the catalyst (the removal rate is still >94% after 5 cycles).

[0052] Buffering pH fluctuations: Aluminum species (such as -OH) on the catalyst surface can undergo protonation / deprotonation at different pH levels, which helps stabilize the interfacial microenvironment. Experiments show that the catalyst of this invention maintains high activity (optimal at neutral pH) within the pH range of 3.0 to 11.0. This is due to the ability of Al to regulate surface charge, avoiding the problem of easy deactivation of single cobalt-based catalysts under alkaline conditions.

[0053] In summary, the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst of this invention uses CoAl2O4 spinel active phase as the core, stabilizes cobalt sites and enhances PDS activation ability through aluminum-cobalt electron synergy; relies on high specific surface area and high-defect biochar support to accelerate mass transfer and provide non-radical electron transfer channels; and ultimately forms SO42-based catalysts. ·- / ·OH is the dominant group, 1 A free radical-non-free radical synergistic oxidation system, supplemented by O2 and surface electron transfer, achieves efficient, rapid, and stable degradation of norfloxacin.

[0054] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0055] All raw materials used in the embodiments of the present invention were obtained through commercial purchase.

[0056] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0057] The technical solution of the present invention will be further illustrated by the following embodiments.

[0058] Example 1: Preparation of aluminum-cobalt bimetallic ionic liquid 0.1 mol of 1-ethyl-3-methylimidazolium chloride was placed in a flask and heated to 80 °C until melted. Then, 0.03 mol of anhydrous aluminum chloride was added and the mixture was magnetically stirred until a homogeneous molten liquid was formed. The temperature was raised to 120 °C and held for 2 h. Next, 0.06 mol of anhydrous cobalt chloride was added, and the temperature was raised to 150 °C with continuous stirring for 12 h. After cooling to room temperature, a deep blue aluminum-cobalt bimetallic ionic liquid was obtained, denoted as [Emim]Cl-0.3AlCl3-0.6CoCl2.

[0059] Example 2: One-step pyrolysis preparation of aluminum-cobalt bimetallic ionic liquid modified biochar catalyst Weigh 12.5 g of poplar wood powder and add 25 g of the [Emim]Cl-0.3AlCl3-0.6CoCl2 aluminum-cobalt bimetallic ionic liquid prepared in Example 1. After mixing evenly, preheat at 150 °C for 12 h to allow the bimetallic ionic liquid to fully impregnate the poplar wood powder. Transfer the preheated solid to a vacuum tube furnace and heat it to 800 °C at a rate of 5 °C / min under a nitrogen atmosphere and hold for 2 h. After naturally cooling to room temperature, remove the product, wash repeatedly with deionized water to remove inorganic salts, and vacuum dry to obtain the target catalyst, denoted as Al / Co-0.5-PBC.

[0060] Example 3: Two-step pyrolysis preparation of aluminum-cobalt bimetallic ionic liquid modified biochar catalyst First, biomass raw material (poplar wood powder) was placed in a vacuum tube furnace and heated to 500°C at 6°C / min under a nitrogen atmosphere. The mixture was then pyrolyzed at 500°C for 12 h to prepare a biochar precursor. Subsequently, 12.5 g of the obtained biochar precursor was mixed with 25 g of the [Emim]Cl-0.3AlCl3-0.6CoCl2 aluminum-cobalt bimetallic ionic liquid prepared in Example 1. The mixture was then heated to 800°C at 5°C / min under a nitrogen atmosphere and pyrolyzed again at 800°C for 2 h to obtain the two-step pyrolysis material, denoted as Al / Co-0.5-T-PBC.

[0061] Example 4 0.1 mol of 1-ethyl-3-methylimidazolium chloride was placed in a flask and heated to 80 °C until melted. Then, 0.03 mol of anhydrous aluminum chloride was added and the mixture was magnetically stirred until a homogeneous molten liquid was formed. The temperature was raised to 120 °C and held for 2 h. Next, 0.03 mol of anhydrous cobalt chloride was added, and the temperature was raised to 150 °C with continuous stirring for 12 h. After cooling to room temperature, a deep blue aluminum-cobalt bimetallic ionic liquid was obtained, denoted as [Emim]Cl-0.3AlCl3-0.3CoCl2.

[0062] An aluminum-cobalt bimetallic ionic liquid modified biochar catalyst was prepared using [Emim]Cl-0.3AlCl3-0.3CoCl2. The specific preparation method was the same as in Example 2, and the resulting catalyst was denoted as Al / Co-PBC.

[0063] Example 5 0.1 mol of 1-ethyl-3-methylimidazolium chloride was placed in a flask and heated to 80 °C until melted. Then, 0.06 mol of anhydrous aluminum chloride was added and the mixture was magnetically stirred until a homogeneous molten liquid was formed. The temperature was raised to 120 °C and held for 2 h. Next, 0.03 mol of anhydrous cobalt chloride was added, and the temperature was raised to 150 °C with continuous stirring for 12 h. After cooling to room temperature, a deep blue aluminum-cobalt bimetallic ionic liquid was obtained, denoted as [Emim]Cl-0.6AlCl3-0.3CoCl2.

[0064] An aluminum-cobalt bimetallic ionic liquid modified biochar catalyst was prepared using [Emim]Cl-0.6AlCl3-0.3CoCl2. The specific preparation method was the same as in Example 2, and the resulting catalyst was designated as Al / Co-2-PBC.

[0065] Comparative Example 1: Preparation of Unmodified Biochar Except for not adding aluminum-cobalt bimetallic ionic liquid, the remaining steps are the same as in Example 2, and an unmodified sample is obtained, denoted as UPBC.

[0066] Comparative Example 2: Preparation of a single cobalt-based modified catalyst Preparation of cobalt-based metal ionic liquid: 1-ethyl-3-methylimidazolium chloride and anhydrous cobalt chloride were mixed in a flask at a molar ratio of 2:1, heated to 80 °C under a nitrogen atmosphere, and magnetically stirred until a homogeneous molten liquid was formed; then the temperature was raised to 150 °C and the reaction was stirred for 12 h. After the reaction was completed, the mixture was cooled to room temperature to obtain the cobalt-based metal ionic liquid.

[0067] 12.5 g of poplar wood powder was weighed and added to 25 g of cobalt-based metal ionic liquid. After mixing, the mixture was preheated at 150 °C for 12 h. Subsequently, the temperature was increased to 800 °C at 5 °C / min under a nitrogen atmosphere and held for 2 h. After cooling, the product was removed, washed with deionized water, and dried to obtain a single cobalt-based modified catalyst, denoted as Co-PBC.

[0068] Performance testing (1) Norfloxacin degradation performance test A batch reaction experiment was conducted in 100 mL of an aqueous solution containing norfloxacin. The experimental conditions were: initial norfloxacin concentration of 10 mg / L, catalyst dosage of 0.10 g / L, PDS concentration of 0.5 mM, temperature of 25 ℃, and shaking speed of 180 rpm. Samples were taken at 0, 5, 10, 15, 20, 30, 40, 50, and 60 min, filtered through a 0.22 μm filter membrane, and the norfloxacin concentration in the samples was determined by HPLC-MS / MS. The removal rate and apparent rate constant were calculated.

[0069] First, the effects of one-step and two-step pyrolysis routes on catalytic performance are compared. (See...) Figure 1 The results showed that both Al / Co-0.5-PBC obtained by one-step pyrolysis and Al / Co-0.5-T-PBC obtained by two-step pyrolysis could achieve near-complete removal of norfloxacin within 60 min, indicating that both routes can construct highly efficient catalytic systems. Considering that the one-step pyrolysis process is simpler, requires fewer pyrolysis steps, and has no performance disadvantage, the one-step pyrolysis route is preferred.

[0070] Based on the one-step pyrolysis route, the catalytic performance of materials obtained from different bimetallic ionic liquids was further compared, see [reference needed]. Figure 2 (a) The results showed that the unmodified UPBC removed only 32.6% of norfloxacin within 60 min, and the apparent rate constant k obs It is 0.007 min. -1 This indicates that its PDS activation ability is relatively weak; the removal rate of Al / Co-2-PBC at 60 min was 71.3%, k obs It is 0.015 min. -1 The removal rate of Al / Co-PBC at 60 min was 86.1%, k obs It is 0.025 min. -1 Al / Co-0.5-PBC performed best, achieving a norfloxacin removal rate of over 99% after 60 minutes. obs Increased to 0.070 min -1 This result indicates that the bimetallic ionic liquid ratio corresponding to Al / Co-0.5-PBC is more conducive to constructing highly efficient active sites and promoting PDS activation.

[0071] For a further comparison of the removal efficiency of different catalysts for norfloxacin in the absence of PDS, see [link to relevant documentation]. Figure 2(b) The results showed that the removal rates of norfloxacin by Al / Co-2-PBC, Al / Co-PBC and Al / Co-0.5-PBC within 60 min were only about 15%~19%, which was much lower than the removal level under the condition of adding PDS. This indicates that the rapid removal of norfloxacin in the system of the present invention mainly comes from the oxidative degradation initiated by catalytic activation of PDS, rather than simple adsorption.

[0072] Further comparison with the single Co-modified sample Co-PBC yielded the following results: Figure 3 The results showed that Co-PBC achieved a removal rate of 71.71% for norfloxacin at 60 min, k obs 0.020 min -1 The concentration of norfloxacin was significantly lower than that of Al / Co-0.5-PBC. In particular, at the initial stage of the reaction, the residual amount of norfloxacin in the Co-PBC system was still 82.0% after 5 min, while that in the Al / Co-0.5-PBC system had dropped to 51.2%, indicating that the bimetallic system can establish an effective oxidation reaction flux more quickly and significantly improve the initial degradation rate.

[0073] (2) Morphological, structural and compositional characteristics SEM ( Figure 4 The results showed that the surface of unmodified UPBC was relatively flat and dense, retaining obvious wood fiber groove structure and few pores; while the surface of Al / Co-0.5-PBC was obviously rough and loose, with a large number of granular clusters, wrinkles and pore structures, indicating that the bimetallic ionic liquid significantly promoted the destruction of the biomass skeleton, surface reconstruction and pore structure development; Co-PBC also showed surface roughening and granulation characteristics, but its overall structural characteristics were slightly weaker than those of Al / Co-0.5-PBC.

[0074] The specific surface area, pore structure, and EDS information of the material are shown in Table 1. The results show that the BET specific surface area of ​​UPBC is only 62.33 m². 2 / g, average pore size 3.07 nm, pore volume 0.05 cm³ / g 3 / g; while the specific surface area of ​​Al / Co-0.5-PBC increased to 178.47 m². 2 / g, with an average pore size of 2.59 nm and a pore volume of 0.15 cm³. 3 / g; the specific surface area of ​​Co-PBC is 163.71 m². 2 / g, with an average pore size of 2.76 nm and a pore volume of 0.14 cm³. 3 / g. The content of N, O and metal elements on the surface of the modified material is significantly increased, indicating that the ionic liquid pyrolysis process simultaneously achieves heteroatom doping and metal introduction.

[0075] Table 1. Material specific surface area, pore structure, and EDS information HR-TEM ( Figure 4 The results in (d) and (e) show that the 0.286 nm and 0.248 nm lattice fringes in Al / Co-0.5-PBC can be attributed to the (200) and (311) crystal planes of spinel-type CoAl2O4, respectively, while the 0.202 nm lattice fringes correspond to the metallic Co (111) crystal plane. In contrast, the 0.243 nm and 0.212 nm lattice fringes in Co-PBC correspond to the Co3O4 (311) and CoO (400) crystal planes, respectively, and the metallic Co (111) crystal plane can also be observed. This indicates that aluminum-cobalt bimetallic ionic liquids are more conducive to the formation of the CoAl2O4 composite active phase, while single Co-based metal ionic liquids tend to form the cobalt oxide phase.

[0076] XRD ( Figure 5 The results in (a) further confirm the above conclusions. UPBC mainly exhibits an amorphous carbon structure; Al / Co-0.5-PBC shows obvious diffraction peaks at 30.4°, 36.1°, 59.1°, and 64.7°, corresponding to the (220), (311), (642), and (440) crystal planes of CoAl2O4, respectively, while diffraction peaks related to metallic Co appear at 47.6° and 51.1°; Co-PBC mainly shows diffraction peaks related to Co3O4, accompanied by a small amount of metallic Co or low-valence Co oxide peaks. Raman results ( Figure 5 (b) indicates that the I of Al / Co-0.5-PBC D / I G The value reached 3.27, which is higher than 2.75 for Co-PBC and UPBC, indicating that bimetallic ionic liquid activation significantly improved the degree of defects in the carbon framework.

[0077] FT-IR ( Figure 6 The results in (a) show that the three materials at 3437 cm⁻¹ -1 1631 cm -1 and 1106 cm -1 Absorption peaks for -OH, C=C, and CO were observed in the vicinity; the modified material showed absorption peaks at 591 cm⁻¹. -1 A Co-O absorption peak appears nearby, while the Al / Co-0.5-PBC peak is at 475 cm⁻¹. -1 The presence of further Al-O absorption peaks nearby indicates that both Al and Co successfully participated in the material construction and formed a metal-oxygen coordination structure. XPS results showed that both Al / Co-0.5-PBC and Co-PBC detected Co 2p characteristic peaks, and Al / Co-0.5-PBC also detected Al 2p peaks (…). Figure 6In (a)); MO-related peaks were observed in the O 1s high-resolution spectra of both, indicating the formation of obvious metal-oxygen bonds ( Figure 7 (a) The Co 2p peak of Al / Co-0.5-PBC is consistent with the CoAl2O4 related structure, while the Co 2p of Co-PBC shows Co... 2 + / Co 3+ coexist( Figure 7 (b)

[0078] (3) Environmental adaptability test To evaluate the suitability of the catalyst of this invention in complex aquatic environments, pH ( Figure 8 (a) ), coexisting anions and humic acid ( Figure 8 The effect of (b) on the degradation performance of norfloxacin in the Al / Co-0.5-PBC / PDS system.

[0079] Within a pH range of 3.0–11.0, Al / Co-0.5-PBC could continuously degrade norfloxacin, but the reaction rate and final removal rate varied. The best performance was observed under neutral conditions, with a removal rate exceeding 99% after 60 minutes at pH 7.0. obs It is 0.081 min. -1 The removal rates at pH = 5.0 and 3.0 were 98.1% and 96.4% after 60 min, respectively. obs The values ​​were 0.061 and 0.049 min, respectively. -1 The removal rate decreased under alkaline conditions; at pH = 9.0 and 11.0, the removal rates after 60 min were 87.7% and 83.1%, respectively. obs The values ​​were 0.032 and 0.027 min, respectively. -1 This indicates that the catalyst of the present invention maintains high activity over a wide pH range, with the optimal application range being neutral to weakly acidic conditions.

[0080] Regarding the influence of coexisting anions, HCO3 - It exhibited the strongest inhibitory effect, with norfloxacin removal rates of 67.2%, 60.1%, and 57.9% at concentrations of 5, 20, and 50 mg / L, respectively; Cl - It exhibited moderate inhibition, with removal rates of 84.6%, 77.9%, and 70.8% at concentrations of 5, 20, and 50 mg / L, respectively; SO4 2- and NO3 - The impact is relatively small, especially on SO4. 2- The removal rate remained at 89.7%–94.9% within the range of 5–50 mg / L, NO3 -It causes almost no noticeable interference. This indicates that the system of the present invention has good tolerance to most common anions.

[0081] Regarding the effect of humic acid, humic acid exhibited a concentration-dependent inhibitory effect: when the humic acid concentration was 5 mg / L, the removal rate of norfloxacin could still reach 97.0%; when the humic acid concentration was increased to 20 and 50 mg / L, the removal rate decreased to 89.6% and 83.9%, respectively. This indicates that the system of the present invention can still maintain a high removal efficiency under the condition of low concentration of natural organic matter.

[0082] (4) Cyclic stability and actual water sample application Continuous reuse experiment of Al / Co-0.5-PBC ( Figure 9 (a) The results showed that after four consecutive cycles, the removal rates of norfloxacin at 60 min were 97.8%, 96.8%, 94.9%, and 94.8%, respectively. obs Although it gradually decreased to about 0.040 min -1 However, the overall level remains high, indicating that the catalyst has good durability and potential for repeated use.

[0083] The concentration of Co leaching in the filtrate during the circulation process was detected by ICP-MS. Figure 9 (b) The results showed that the Co leaching concentration in the Al / Co-0.5-PBC system was only 0.09~0.18 mg / L, significantly lower than the 0.89 mg / L when Co-PBC was used only once. This indicates that the introduction of Al helps to improve the immobilization state of Co and reduce the risk of metal leaching.

[0084] In practical water sample applications ( Figure 10 The catalyst of this invention achieved removal rates of 99.4%, 99.1%, and 97.9% for norfloxacin in deionized water, tap water, and river water, respectively, indicating that the Al / Co-0.5-PBC / PDS system still has high removal efficiency and good environmental adaptability in real water conditions.

[0085] (5) Analysis of active species and catalytic mechanism To elucidate the mechanism of Al / Co-0.5-PBC activation of PDS in the degradation of norfloxacin, quenching experiments, EPR detection, and electrochemical tests were conducted.

[0086] The quenching experiment results show that ( Figure 11 In (a) of the control group, the removal rate of norfloxacin was greater than 99% at 60 min. After the addition of MeOH, the removal rate decreased to 53.5% at 60 min. obs Reduced to 0.008 min -1 This indicates that SO4·- ·OH plays an important role in the system; after the addition of TBA, the removal rate was 74.8% after 60 min, k obs It is 0.017 min. -1 This indicates that ·OH participates in the reaction, but its contribution is less than that of SO4· - The removal rate also decreased to some extent after adding FFA and p-BQ, indicating that... 1 O2 and O2 ·- It also participates in the reaction, but plays a more synergistic role. Therefore, it can be seen that SO4· - ·OH is the dominant active species, accompanied by O2. ·- and 1 O2 participates.

[0087] The EPR results further prove that ( Figure 11 In (b)-(d) of the Al / Co-0.5-PBC / PDS system, DMPO-·OH / SO4 can be detected. ·- DMPO-O2 ·- and TEMP- 1 The characteristic signals of O2 indicate that SO4 ·- ·OH, O2 ·- and 1 O2 is generated during the reaction. Compared with Co-PBC, Al / Co-0.5-PBC has a higher EPR signal intensity ( Figure 12 This indicates that the synergistic effect of aluminum-cobalt bimetals can more effectively promote PDS activation and enhance the generation of multiple active species.

[0088] Electrochemical tests showed that Al / Co-0.5-PBC had a lower charge transfer resistance than Co-PBC. (Nyquist plot) Figure 13 In (a) the semicircle diameter is significantly reduced, indicating smoother electron transfer at the interface; in the chronocurrent test ( Figure 13 In (b), when PDS was added at 200 s, Al / Co-0.5-PBC showed a more pronounced current response, and the current change was also stronger after norfloxacin was added at 400 s; LSV results showed that ( Figure 13 In (c), the overall current response shifted upward after the addition of PDS, and was further enhanced after the addition of norfloxacin. These results indicate that, in addition to the free radical oxidation pathway, the system of this invention also has a surface-mediated electron transfer pathway, thereby forming a synergistic mechanism between free radicals and non-free radicals.

[0089] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst, characterized in that, Includes the following steps: The aluminum-cobalt bimetallic ionic liquid was mixed with biomass raw material and preheated. The preheated mixture was then subjected to high-temperature pyrolysis under an inert atmosphere. After cooling, the mixture was washed and dried to obtain the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst. Alternatively, biomass raw materials are pyrolyzed at a low temperature of 400~600℃ to obtain a biochar precursor; the biochar precursor is mixed with an aluminum-cobalt bimetallic ionic liquid and pyrolyzed at a high temperature of 700~900℃ to obtain the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst.

2. The method for preparing the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst according to claim 1, characterized in that, The preparation process of the aluminum-cobalt bimetallic ionic liquid is as follows: first, the imidazole ionic liquid is melted at 70~100 °C, soluble aluminum salt is added and reacted at 100~130 °C for 1~4 h, then soluble cobalt salt is added and reacted at 130~170 °C for 8~16 h, and the aluminum-cobalt bimetallic ionic liquid is obtained after cooling.

3. The method for preparing the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst according to claim 2, characterized in that, The imidazole ionic liquid is 1-ethyl-3-methylimidazolium chloride, the soluble aluminum salt is aluminum chloride, and the soluble cobalt salt is cobalt chloride.

4. The method for preparing the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst according to claim 3, characterized in that, The molar ratio of 1-ethyl-3-methylimidazolium chloride, aluminum chloride, and cobalt chloride is 1:(0.3~0.6):(0.3~0.6).

5. The method for preparing the aluminum-cobalt bimetallic ionic liquid-modified biochar catalyst according to claim 1, characterized in that, The mass ratio of the aluminum-cobalt bimetallic ionic liquid to the biomass raw material is 2:

1.

6. The method for preparing the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst according to claim 1, characterized in that, The preheating temperature is 150 ℃, and the time is 6~12 h.

7. The method for preparing the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst according to claim 1, characterized in that, The high-temperature pyrolysis was carried out under an inert atmosphere at a temperature of 800 °C for 2 h.

8. A bimetallic aluminum-cobalt ionic liquid modified biochar catalyst, characterized in that, It is prepared according to any one of claims 1 to 7.

9. The application of the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst as described in claim 8 in the degradation of organic pollutants by activated persulfate, characterized in that, The organic pollutant is a quinolone antibiotic.

10. The application according to claim 9, characterized in that, The dosage of the aluminum-cobalt bimetallic ionic liquid modified biochar catalyst is 0.05~0.20 g / L, and the persulfate concentration is 0.1~2.0 mM.

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