Microbial-based composite electrode and application thereof in purifying amc wastewater

Abstract

The application discloses a microbial-based composite electrode and application thereof in purifying AMC wastewater, and belongs to the technical field of electrochemical water treatment, wherein the microbial-based composite electrode takes aspergillus niger spores as active material, takes Fe3O4 solid powder as catalytic material, and takes foam metal as a current collector matrix; the aspergillus niger spores are wrapped in the Fe3O4 solid powder to form aspergillus niger spore@Fe3O4 core-shell structure; the aspergillus niger spore@Fe3O4 core-shell structure is uniformly distributed in the three-dimensional porous structure of the foam metal through a bonding agent; and the microbial-based composite electrode can be used as a cathode to construct an electro-Fenton-biosorption coupling system and can be used for purifying AMC wastewater. The application utilizes the electro-Fenton-biosorption coupling technology, destroys the structure of an AMC complex through electro-Fenton oxidation, releases heavy metal ions, and realizes the adsorption of the heavy metal ions through the biosorption effect of the aspergillus niger spores, so that the AMC wastewater can be well degraded, the reaction system is stable, operation is convenient and controllable, there is no subsequent pollution problem, and the application has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical water treatment, and particularly relates to a microbial-based composite electrode and application thereof in purifying antibiotic-metal complex (AMC) wastewater. BACKGROUND

[0002] Antibiotic-metal complexes (AMCs) are a new type of emerging refractory complex organic pollutants, which exist widely in various water bodies. Since trace amounts of antibiotics and heavy metals remain after sewage treatment in the biochemical section, the structure of the antibiotics contains ionizable groups (hydroxyl, amino and carboxyl groups) and N, O and S heteroatoms that can form complexes with various heavy metal ions. Therefore, the two can easily form chelates, which in turn cause frame delocalization, reduce the polarity of the entire chelate system, and make them usually insoluble or insoluble in water medium, and present variable morphology and structure under different water medium conditions. In addition, the affinity between AMCs and bacterial cell membranes enables them to penetrate cells and bioaccumulate, inducing the growth of drug-resistant bacteria and genes, and the environmental risk is prominent.

[0003] Currently, the treatment of AMCs mainly adopts the adsorption method. However, the combination of antibiotics and heavy metals increases the molecular weight, which brings great difficulty to physical adsorption. Meanwhile, there are many combinations of antibiotics and heavy metals, and the adsorption method often has selectivity. More importantly, AMCs are not degraded in the adsorption process, thereby producing secondary pollution materials. The advanced oxidation method can mineralize organic macromolecules, and the electro-Fenton method is particularly suitable for this purpose. The electro-Fenton method is driven by electrical energy and belongs to the "carbon neutral" green water treatment technology system. The core of the method is that H2O2 generated on the electrode can attack organic matter indiscriminately to mineralize it.

[0004] Traditional heavy metal treatment methods mainly include chemical treatment, evaporation concentration, reverse osmosis and adsorption, etc. Compared with the above-mentioned methods, the adsorption method has the advantages of low cost, simplicity and flexibility, especially the biological adsorption method, which is suitable for low-carbon treatment of large-volume low-concentration heavy metal wastewater. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and to provide a microbial-based composite electrode. The electro-Fenton method is combined with the biological adsorption method, and the electro-Fenton-biological adsorption coupling technology is used to destroy the structure of the AMCs complex through electro-Fenton oxidation, release heavy metal ions, and realize the adsorption of heavy metal ions through the biological adsorption of Aspergillus niger spores. The AMCs wastewater can be well degraded, the reaction system is stable, the operation is convenient and controllable, the catalyst does not need to be recovered, there is no subsequent pollution problem, and the method has good application prospect.

[0006] To solve the above-mentioned technical problems, the present invention provides a microbial-based composite electrode. The microbial-based composite electrode uses Aspergillus niger spores as the electrode active material, Fe3O4 solid powder as the catalyst material, and foamed metal as the current collector matrix. The Aspergillus niger spores are encapsulated in Fe3O4 solid powder to form an Aspergillus niger spore@Fe3O4 core-shell structure. The Aspergillus niger spore@Fe3O4 core-shell structure is uniformly distributed in the three-dimensional porous structure of the foamed metal by a binder.

[0007] Preferably, the Aspergillus niger spores have a diameter of 2 μm and an ordered pore diameter of 0–4 nm on their surface.

[0008] Preferably, the contents of C, N, O and P in the Aspergillus niger spores are 62%, 10.5%, 22.8% and 3%, respectively; the Aspergillus niger spores contain oxygen-containing functional groups and CN bonds, wherein the oxygen-containing functional groups are -OH, -COOH, CO and C=O.

[0009] Preferably, the adhesive is PTFE, SBR, PAA, or CMC.

[0010] Preferably, the foamed metal is foamed nickel, foamed copper, or foamed iron, and the porosity of the foamed metal is 98%.

[0011] The microbial-based composite electrode of this invention mainly consists of Aspergillus niger spores, Fe3O4, and foamed metal, which serve as the active material, catalytic material, and current collector, respectively. The presence of a binder creates a dual-interface structure: one interface between Aspergillus niger spores and Fe3O4, and another interface between Aspergillus niger spores@Fe3O4 and foamed metal. Adjusting the composition, concentration, reaction time, and method of the binder can alter the structure at the interfaces, thereby controlling the overall structure and improving the performance of the composite electrode, achieving a synergistic effect of activity, conductivity, and stability.

[0012] Aspergillus niger spores [purchased from the National Center for Medical Microbial Culture Collection (CMCC) strain (strain number: Aspergillus niger CMCC98003)] are the reproductive dormant forms of the Aspergillus niger fungus. Their natural properties coincide with the cathode structure and components required for efficient H2O2 production. Aspergillus niger spores can produce 60-80% H2O2 under relatively high voltages and exhibit 2e-ORR selectivity. Furthermore, the functional groups and electronegativity on the surface of Aspergillus niger spores enable them to adsorb various heavy metals, including Cu. 2+ The adsorption capacity was 12.1 times that of rice straw of equivalent mass, and it was effective against Pb at an initial concentration of 30 mg / L. 2+ Cd 2+ Hg 2+The removal rates reached 96.6%, 99.85%, and 99.7%, respectively. This demonstrates that Aspergillus niger spores combine electrochemical oxygen reduction activity and heavy metal adsorption characteristics, making them suitable as active materials for constructing electro-Fenton cathode devices.

[0013] The construction of electro-Fenton cathode devices requires not only active materials but also Fe catalysts and current collectors. Preparing solid Fe3O4 into a water-based magnetofluid to encapsulate Aspergillus niger spores not only serves as a protective layer, reducing the impact of water, gas, and current on the Aspergillus niger spore clusters, but also acts as a "link" between the current collector and the Aspergillus niger spores, guiding the current to the spore surface. Furthermore, the three-dimensional structure of Fe3O4 can also achieve Fe… 2+ with Fe 3+ Redox, Fe 2+ As an electron donor, it can effectively catalyze the electro-Fenton reaction. Furthermore, foamed metal materials (iron, copper, nickel, etc.) are ideal current collectors, exhibiting low resistance during current and electron transfer. Their three-dimensional open structure and porosity not only provide a large specific surface area to increase active sites but also facilitate O2 transfer. This invention combines Aspergillus niger spores, Fe3O4, and foamed metal to construct an Aspergillus niger spore@Fe3O4 / foamed metal composite electrode. By regulating the interface structure of the three components, the stability and activity synergy of the Aspergillus niger spore cathode device are enhanced, achieving a leap from microscopic structural control to macroscopic applications.

[0014] To address the aforementioned technical problems, this invention also provides the application of a microbial-based composite electrode in constructing an electro-Fenton-bioadsorption coupling system, specifically using the microbial-based composite electrode as the cathode of the electro-Fenton-bioadsorption coupling system.

[0015] As the cathode of the electro-Fenton-bioadsorption coupling system, the microbial-based composite electrode enables the electro-Fenton cathode to have both H2O2 production and heavy metal adsorption capabilities, achieving a leap from microscopic material control to macroscopic application stability.

[0016] To address the aforementioned technical problems, this invention also provides the application of an electro-Fenton-bioadsorption coupling system in the purification of AMCs wastewater, wherein the antibiotics are mainly tetracyclines (chlortetracycline, oxytetracycline, tetracycline), sulfonamides (sulfamethoxazole, sulfapyridine, thiamphenicol), macrolides (erythromycin, roxithromycin), quinolones (ciprofloxacin, ofloxacin, norfloxacin), and chloramphenicol (thiamphenicol), etc.; the heavy metals are mainly Cu, Zn, Pb, Cd, Ni, Hg, etc.

[0017] The macroscopic process of removing AMCs from wastewater using the electro-Fenton-bioadsorption coupling system involves AMCs transferring mass from infinity to the surface of the microbial-based composite electrode of the electro-Fenton-bioadsorption coupling system. First, H2O2 is generated in situ by the electrode, which oxidizes and destroys the AMC complex structure on the electrode surface, releasing heavy metal ions. Subsequently, the electrode uses its own bioadsorption properties to capture free heavy metal ions, achieving heavy metal ion adsorption. The former process involves the electrochemical cathode oxygen reduction process of the microbial-based composite electrode material, while the latter involves the microbial adsorption of heavy metal ions. Through the interfacial structure regulation among Aspergillus niger spores, Fe3O4, and foamed metal, the synergistic effect of the composite cathode activity, conductivity, and stability is achieved.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0019] 1. This invention improves the 2e-ORR selectivity and electrostatic attraction coordination complexation by regulating the electronegativity, oxygen-containing functional groups and pore size of Aspergillus niger spores, i.e., the "three-in-one" regulation of electronic, molecular and nanoscale, thereby improving the H2O2 yield and adsorption performance.

[0020] 2. By constructing a microbial-based composite electrode of Aspergillus niger spores@Fe3O4 / foam metal, the structure of the interface between Aspergillus niger spores@Fe3O4 and foam metal is regulated to achieve synergistic control of stability, activity and conductivity from microscopic materials to macroscopic electrode devices;

[0021] 3. By regulating the structure of Aspergillus niger spores and the interface structure of Aspergillus niger spores@Fe3O4 / foam metal, based on the principle of "structure-activity relationship", the application of electro-Fenton-bioadsorption coupling technology is enhanced, and the enhanced degradation of AMCs is finally achieved. The reaction system is stable, the operation is convenient and controllable, there is no need for catalyst recovery, and there are no subsequent pollution problems, which has good application prospects. Attached Figure Description

[0022] Figure 1 This is a structural diagram of a microbial-based composite electrode;

[0023] Figure 2 The graph shows the properties of Aspergillus niger spores, their oxygen reduction activity, and their heavy metal adsorption capacity.

[0024] Figure 3 It is a chemical process for removing AMCs from wastewater using an electro-Fenton-bioadsorption coupling system;

[0025] Figure 4 It is the process of treating AMCs wastewater using an electro-Fenton-bioadsorption coupling system. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a microbial-based composite electrode. The microbial-based composite electrode uses Aspergillus niger spores as the electrode active material, Fe3O4 solid powder as the catalyst material, and foamed metal as the current collector matrix. The Aspergillus niger spores are encapsulated within the Fe3O4 solid powder to form an Aspergillus niger spore@Fe3O4 core-shell structure. This Aspergillus niger spore@Fe3O4 core-shell structure is uniformly distributed within the three-dimensional porous structure of the foamed metal by a binder. Figure 1 As shown.

[0029] Aspergillus niger spores are naturally occurring organic materials with regular morphology (small spheres with a diameter of 2 μm) and a large specific surface area; their surface micropore diameter is 0–4 nm. Figure 2 (a) shows that the surface contains a large number of oxygen-containing functional groups such as -OH, -COOH, CO, and C=O, as well as CN bonds. Figure 2 (b) shows that the contents of C, N, O, and P in Aspergillus niger spores are 62%, 10.5%, 22.8%, and 3%, respectively, which can effectively achieve elemental self-doping with high N content. Figure 2 (c) shows the process of the 2-electron ORR reaction. Furthermore, the process involves O2 mass transfer from infinity to the electrode surface, followed by electron gain and loss to generate H2O2. This requires enhancing two processes: the oxygen mass transfer process and the 2-electron gain and loss process. The micropores on the surface of *Aspergillus niger* spores can effectively enhance oxygen transfer. Simultaneously, the spores are doped with heteroatoms (N, P, etc.) and possess oxygen-containing functional groups, which can effectively enhance the 2-electron gain and loss process. Therefore, *Aspergillus niger* spores are an excellent 2-electron ORR electrode active material. As a cathode, *Aspergillus niger* spores can produce 60-80% H2O2 at higher voltages. Figure 2 (d) shows that the ORR process tends to favor 2e-ORR ( Figure 2 (e) shown). Furthermore, the functional groups and electronegativity on the surface of Aspergillus niger spores enable them to adsorb various heavy metals, including Cu. 2+ The adsorption capacity is 12.1 times that of rice straw of equivalent mass. Figure 2 (f) shows that for Pb with an initial concentration of 30 mg / L 2+ Cd 2+ Hg 2+ The removal rates reached 96.6%, 99.85%, and 99.7%, respectively.Figure 2 (g) shown) and has adsorption selectivity ( Figure 2 (h) is shown.

[0030] However, Aspergillus niger spores have poor electrical conductivity, necessitating the use of composite current collectors to transfer current. This invention prepares a water-based magnetic fluid from Fe3O4 solid powder to encapsulate Aspergillus niger spores. This fluid not only acts as a protective layer, reducing the impact of water, air, and current on the spore clusters, but also serves as a "link" between the current collector and the spores, guiding the current to the spore surface. Furthermore, the three-dimensional structure of Fe3O4 allows for the realization of Fe... 2+ with Fe 3+ Redox, Fe 2+ As an electron donor, it can effectively catalyze the electro-Fenton reaction.

[0031] Preferably, the adhesive is PTFE, SBR, PAA, or CMC.

[0032] In this invention, the active material, catalytic material, and current collector of the microbial-based composite electrode form a dual-interface structure due to the presence of a binder. These interfaces are the interface between Aspergillus niger spores and Fe3O4, and the interface between Aspergillus niger spores@Fe3O4 and the foamed metal. By optimizing the type of binder, molecular order and nano-micro regularity are constructed, and the interfacial structure between Aspergillus niger spores@Fe3O4 and the current collector is controlled, thereby enhancing electron transport capacity and strengthening the conductivity of the composite electrode.

[0033] Preferably, the foamed metal is foamed nickel, foamed copper, or foamed iron, and the porosity of the foamed metal is 98%. Foamed metal materials (iron, copper, nickel, etc.) are ideal current collectors, experiencing low resistance during current and electron transfer. Their three-dimensional open structure and porosity not only provide a large specific surface area to increase active sites but also facilitate O2 transfer. This invention combines Aspergillus niger spores, Fe3O4, and foamed metal to construct an Aspergillus niger spore@Fe3O4 / foamed metal composite electrode. By regulating the interface structure of the three components, the stability and activity synergy of the Aspergillus niger spore cathode device are enhanced, achieving a leap from microscopic structure regulation to macroscopic application.

[0034] This invention achieves synergistic control of H2O2 yield and heavy metal adsorption efficiency through the "three-in-one" regulation of the electronic, molecular, and nanoscale of Aspergillus niger spores. By regulating the interface structure between Aspergillus niger spores@Fe3O4 and foamed metal, it achieves synergistic control of stability, activity, and conductivity from the microscopic material level to the macroscopic electrode device level. By exploring the mechanism by which the bulk and interface structures of melanin spores enhance the electro-Fenton-bioadsorption coupling process for AMC removal, the "structure-activity relationship" is clarified. These research results will elucidate the key scientific issues in enhancing AMC removal through the regulation of the Aspergillus niger spore cathode structure from a microscopic perspective, providing a scientific basis and theoretical foundation for the discovery of new materials, methods, and technologies for AMC pollution control in the environment.

[0035] Example 2

[0036] This embodiment provides an application of a microbial-based composite electrode in constructing an electro-Fenton-bioadsorption coupling system, specifically using the microbial-based composite electrode as the cathode of the electro-Fenton-bioadsorption coupling system.

[0037] As the cathode of the electro-Fenton-bioadsorption coupling system, the microbial-based composite electrode enables the electro-Fenton cathode to have both H2O2 production and heavy metal adsorption capabilities, achieving a leap from microscopic material control to macroscopic application stability.

[0038] Example 3

[0039] This embodiment uses tetracycline-Cu(II) as an example to briefly describe the application of the electro-Fenton-bioadsorption coupling system in the purification of AMCs wastewater.

[0040] Wastewater samples containing tetracycline (20 mg / L)-Cu(II) (30 mg / L) prepared in the laboratory were added to an electro-Fenton-bioadsorption coupling system, using an iron-based electrode as the anode and a DC regulated power supply to control the current density at 50 mA / cm². 2Purified samples collected at different time points were filtered through a 0.22 μm filter membrane. The removal rates of antibiotics, total organic carbon (TOC), and heavy metals at different time points were determined to explore the quantitative relationships among them. TOC was measured using a TOC analyzer. Tetracycline was analyzed using a high-performance liquid chromatography (HPLC) system with a BEH C18 column (250 mm × 4.6 mm, 5 μm), a mobile phase of a mixture of 75% oxalic acid (0.02 M) and 25% acetonitrile, and a flow rate of 1.2 mL / min. Liquid chromatography-mass spectrometry (LC-MS / MS) was used to resolve intermediate substances in the tetracycline degradation process. The liquid chromatography separation system was an Acquity UPLC device (Waters) equipped with a Waters-BEH C18 column (1 mm × 50 mm, 1.7 μm). The column temperature was 40 °C, the mobile phase was pure acetonitrile: 0.1 formic acid = 30:70, and the flow rate was 0.1 mL / min. -1 The mass spectrometry conditions were as follows: Xevo TQ-S quadrupole mass spectrometer, EIS source, positive ion mode. First, a positive ion scan was performed based on the predicted substances, followed by a precursor ion scan. The ion source temperature was 150℃, the degassing temperature was 350℃, the capillary voltage was 3kV, the cone voltage was 30V, the collision voltage was 10eV, and the degassing rate was 650L / hr. Heavy metal ions were detected using IPC-MS.

[0041] Experimental results showed that the removal rate of tetracycline stabilized at around 99.7% after about 30 minutes. The total organic carbon (TOC) removal rate also showed an increasing trend during the tetracycline degradation process, reaching 83.8% after 30 minutes. During the tetracycline degradation process, heavy metal ions Cu(II) were released and simultaneously bioadsorbed by the microbial-based composite electrode. Once the tetracycline removal rate stabilized, the Cu(II) removal rate also stabilized, reaching 92.8% after 30 minutes (Table 1).

[0042] Table 1. Removal rates of antibiotics, total organic carbon (TOC), and heavy metals at different time points.

[0043] Time (min) Tetracycline removal rate (%) TOC removal rate (%) Cu(II) removal rate (%) 5 62.8 11.8 56.4 10 80.3 40.5 75.9 15 85.7 53.6 83.6 20 95.3 68.5 87.6 25 97.8 79.5 91.6 30 99.7 83.8 92.8

[0044] The macroscopic process of removing AMCs from wastewater using the electro-Fenton-bioadsorption coupling system of this invention involves AMCs transferring mass from infinity to the surface of the microbial-based composite electrode of the electro-Fenton-bioadsorption coupling system. First, H2O2 is generated in situ by the electrode, oxidizing and destroying the AMC complex structure on the electrode surface, releasing heavy metal ions. Subsequently, the electrode utilizes its own bioadsorption properties to capture the free heavy metal ions, achieving heavy metal ion adsorption. The former process involves the electrochemical cathode oxygen reduction process of the microbial-based composite electrode material, while the latter involves the microbial adsorption of heavy metal ions (e.g., ...). Figure 3 , Figure 4 As shown in the figure, the synergistic effect of composite cathode activity, conductivity and stability can be achieved by regulating the interface structure among Aspergillus niger spores, Fe3O4 and foam metal.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the present invention.

Claims

1. A microbial-based composite electrode, characterized in that: The microbial-based composite electrode uses Aspergillus niger spores as the active material, Fe3O4 solid powder as the catalytic material, and foamed metal as the current collector matrix. The Aspergillus niger spores are encapsulated in Fe3O4 solid powder to form an Aspergillus niger spore@Fe3O4 core-shell structure. The Aspergillus niger spore@Fe3O4 core-shell structure is uniformly distributed in the three-dimensional porous structure of the foamed metal by a binder.

2. The microbial-based composite electrode according to claim 1, characterized in that: The diameter of the Aspergillus niger spores is 2 μm, and the diameter of the ordered pores on the surface is 0~4 nm.

3. The microbial-based composite electrode according to claim 2, characterized in that: The contents of C, N, O and P in the Aspergillus niger spores are 62%, 10.5%, 22.8% and 3%, respectively; the Aspergillus niger spores contain oxygen-containing functional groups and CN bonds.

4. The microbial-based composite electrode according to claim 3, characterized in that: The oxygen-containing functional groups are -OH, -COOH, CO, and C=O.

5. The microbial-based composite electrode according to claim 1, characterized in that: The adhesive is PTFE, SBR, PAA, or CMC.

6. The microbial-based composite electrode according to claim 1, characterized in that: The foamed metal is foamed nickel, foamed copper, or foamed iron.

7. The microbial-based composite electrode according to claim 6, characterized in that: The porosity of the foamed metal is 98%.

8. The application of the microbial-based composite electrode according to any one of claims 1-7 in constructing an electro-Fenton-bioadsorption coupling system, characterized in that: The microbial-based composite electrode is used as the cathode of the electro-Fenton-bioadsorption coupling system.

9. The application of the electro-Fenton-bioadsorption coupling system according to claim 8 in the purification of AMCs wastewater.

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