CoFe-LDH composite hypha biochar electrode material and preparation method and application thereof

Abstract

The CoFe-LDH composite hypha biological electrode material and the preparation method and application thereof are provided for the first time, CoFe-LDH nanosheets vertically grow on hypha biochar (FBC) through an in-situ hydrothermal method to prepare a CoFe-LDH-based composite material (FBC / CoFe-LDH), the CoFe-LDH-based composite material is innovatively used as a CDI anode to remove Cl <->, and the application scene of a traditional LDH-based material is broken through; it is worthy of noting that FBC serves as a carbon substrate, an environment-friendly biomass precursor is ingeniously selected, a net-shaped structure can be formed in a charcoal sheet derived from fungal mycelia, and the FBC is an ideal frame embedded with a metal nanometer material; the prepared CoFe-LDH composite hypha biochar electrode material can be used as an anode of CDI; the electrode material is mainly characterized in that LDH with rich redox active sites is utilized, storage of pseudo-capacitive ions is accelerated through rapid ion embedding / de-embedding, potential aggregation of LDH is prevented through a unique net structure of hypha biochar, and the durability of the electrode material is improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a CoFe-LDH composite mycelial biochar electrode material, its preparation method, and its application. Background Technology

[0002] Chloride ions (Cl) - Cl- is commonly found in industrial wastewater from chemical manufacturing, food processing, metallurgy, and related industries. Currently, Cl- in industrial wastewater... - The concentration of Cl is generally greater than 2000 mg / L, especially in metallurgical wastewater (which accounts for about 12% of the total industrial wastewater discharge in the country). - The concentration was far higher than 2000 mg / L, even reaching 10000 mg / L. High concentrations of Cl... - It poses significant challenges to the environment and infrastructure, including corrosion of industrial pipelines and contamination of drinking water sources through groundwater seepage. Current dechlorination technologies, such as ion exchange, chemical precipitation, evaporation concentration, adsorption, and reverse osmosis, are often limited by high energy consumption, membrane fouling, secondary pollution, operational complexity, and high costs, hindering their widespread application.

[0003] Capacitive deionization (CDI), a promising water treatment separation technology, has received considerable research and attention in recent years due to its energy-saving and environmentally friendly characteristics. Compared with traditional dechlorination methods, CDI offers significant advantages such as simple operation, regenerable electrodes, long-term stability, and significantly reduced energy consumption. This process relies on electrostatic ion adsorption, removing contaminants by forming an electric double layer (EDL) at the electrode-electrolyte interface. System performance is heavily dependent on the electrode material properties. Although porous carbon materials have been extensively studied as traditional CDI electrodes, their practical application faces fundamental limitations, including limited salt adsorption capacity (SAC), poor charge efficiency, and easy anode oxidation. Electrochemical deionization (EDI) using Faraday materials has emerged as a promising alternative, significantly improving desalination performance through redox-active reactions. However, current research mainly focuses on the development of Faraday cathode materials, exploring efficient Cl-… - A crucial gap remains in the study of Faraday anodes for storage. To date, the most studied Cl... - The capture electrodes are mainly Ag / AgCl and Bi / BiOCl systems. Although the Ag / AgCl system has shown effectiveness in high-salinity environments, its performance is compromised due to the high cost of silver and the poor conductivity of AgCl, making it economically impractical. Similarly, the Bi / BiOCl electrode exhibits significant volume expansion during cycling, leading to structural degradation and posing a major challenge to its long-term stability.

[0004] Layered hydrogen hydroxides (LDHs) have attracted widespread attention in various applications such as catalysis, supercapacitors, and energy storage due to their unique layered structure, reversible redox activity, and good charge transport properties. Notably, the positively charged LDH interlayers can effectively insert anions, making them particularly suitable for the removal of anionic pollutants in water treatment applications. However, some challenges remain: (1) limited conductivity restricts charge transfer; (2) interlayer stacking / aggregation reduces active sites and ion diffusion efficiency; and (3) repeated volume expansion / contraction during cycling leads to structural degradation and mechanical instability.

[0005] To address these limitations, researchers have loaded LDH onto the surface of carbon materials (graphene, carbon nanotubes, etc.) as carriers. This reduces the redeposition of nanosheets and enhances their conductivity, thereby improving desalination performance and long-term durability. However, traditional methods using graphene and carbon nanotubes are costly, involve complex synthesis steps, and consume a lot of energy. Furthermore, the desalination performance and efficiency remain low even after LDH is composited with LDH.

[0006] In view of the above-mentioned defects in the existing technology, the purpose of this invention is to develop a new type of capacitive deionization anode material through a triple breakthrough of "mycelial biochar structure design → LDH in-situ growth → anode application innovation", thereby solving the industry problems of LDH material aggregation, poor conductivity and insufficient CDI anode performance. Summary of the Invention

[0007] This invention proposes for the first time a CoFe-LDH composite mycelial biochar electrode material, its preparation method, and its application. A CoFe-LDH-based nanocomposite material (FBC / CoFe-LDH) is prepared by vertically growing CoFe-LDH nanosheets onto mycelial biochar (FBC) using an in-situ hydrothermal method, and is used as a CDI anode for Cl removal. - It is worth noting that FBC, as a carbon substrate, is achieved by cleverly selecting an environmentally friendly biomass precursor. Biochar derived from fungal mycelium forms a network structure, which is an ideal framework for embedding metal nanomaterials. The main feature of this electrode material is that it utilizes LDH with abundant redox active sites to accelerate pseudocapacitive ion storage through rapid ion insertion / deintercalation, and uses the unique network structure of mycelial biochar to prevent potential LDH aggregation and improve its durability.

[0008] The present invention proposes a method for preparing a CoFe-LDH composite mycelial biochar electrode material, comprising: using mycelial biochar as a carrier, and vertically growing CoFe-LDH nanosheets on the inner and outer walls of the mycelial biochar by in-situ hydrothermal method, thereby obtaining the CoFe-LDH composite mycelial biochar composite material.

[0009] Preferably, the mycelial biochar is Aspergillus niger mycelial biochar, which is prepared by the following method:

[0010] S1. Prepare a liquid culture medium containing glucose, peptone, yeast powder, magnesium sulfate and potassium dihydrogen phosphate. Inoculate the Aspergillus niger spore suspension into the liquid culture medium and culture it to obtain Aspergillus niger mycelium.

[0011] S2. After filtering the Aspergillus niger mycelium, wash, dry, and then pyrolyze it under an inert gas to obtain the mycelial biochar.

[0012] Preferably, in step S1, the liquid culture medium comprises: glucose 10-30 g / L, peptone 1-10 g / L, yeast extract 1-5 g / L, magnesium sulfate 0.1-1 g / L and potassium dihydrogen phosphate 0.1-2 g / L.

[0013] Preferably, in step S2, the pyrolysis temperature is 500-700℃ and the heating rate is 1-10℃ / min.

[0014] Preferably, the in-situ hydrothermal method specifically includes:

[0015] Iron source, cobalt source, ammonium fluoride and urea are dissolved in water, and the mycelial biochar is added and mixed. After the mixture is homogenized, a hydrothermal reaction is carried out. CoFe-LDH nanosheets are grown in situ on the surface of the mycelial biochar, thus obtaining the CoFe-LDH composite mycelial biochar electrode material.

[0016] Preferably, the iron source is at least one of ferric nitrate, ferric chloride, ferric sulfate and their hydrates, and the cobalt source is at least one of cobalt nitrate, cobalt chloride, cobalt sulfate and their hydrates;

[0017] Preferably, the molar ratio of the iron source, cobalt source, ammonium fluoride, and urea is 1:2-4:4-8:10-30;

[0018] Preferably, the mass ratio of the iron source to the mycelial biochar is 3-6:1.

[0019] Preferably, the hydrothermal reaction temperature is 100-120℃ and the time is 6-12h.

[0020] This invention also proposes an application of the above-mentioned CoFe-LDH composite mycelial biochar electrode material in capacitive deionization and dechlorination.

[0021] Preferably, the CoFe-LDH composite mycelial biochar electrode material is mixed with a conductive agent, a binder, and a solvent to form an anode slurry, which is then coated onto the surface of a conductive carrier and dried to form an anode; the components, including the anode, are assembled into a capacitor deionization desalination device, which is then used for capacitor deionization dechlorination.

[0022] Preferably, the mass ratio of the CoFe-LDH composite mycelial biochar electrode material, the conductive agent, and the binder is 7-8:1:1-2;

[0023] Preferably, the adhesive is at least one of polyvinylidene fluoride, polytetrafluoroethylene, or polyvinyl alcohol; the solvent is at least one of 1-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide; and the conductive carrier is at least one of graphite plate, nickel foam, copper foil, or titanium mesh.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) This invention provides a CoFe-LDH composite mycelial biochar electrode material, its preparation method and application. CoFe-LDH nanosheets can be vertically grown on the inner and outer walls of mycelial biochar to form a two-dimensional / three-dimensional conductive network structure. The conductive network and layered porosity of the mycelial biochar can effectively slow down the aggregation of CoFe-LDH nanosheets, while promoting electron transfer and ion diffusion, thereby improving the deionization and dechlorination performance of the capacitor.

[0026] (2) The CoFe-LDH composite mycelial biochar electrode material prepared by the present invention has the advantages of high specific capacitance, good conductivity, strong desalination ability and good cycle stability. When used as a capacitor deionization anode and for desalination treatment, it can efficiently remove chloride ions and has good application prospects. Attached Figure Description

[0027] Figure 1 The images show the XRD patterns of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3), CoFe-LDH nanosheets (CoFe-LDH2), and mycelial biochar (FBC) of this invention.

[0028] Figure 2 The images show SEM images of the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2), CoFe-LDH nanosheets (CoFe-LDH2), and mycelial biochar (FBC) of this invention, as well as TEM images of FBC / CoFe-LDH2: (a) is the SEM image of FBC, (b) is the SEM image of CoFe-LDH2, (c) is the SEM image of FBC / CoFe-LDH2, (df) is the TEM image of FBC / CoFe-LDH2, and (gh) is the EDS spectrum of FBC / CoFe-LDH2.

[0029] Figure 3FTIR images of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of the present invention;

[0030] Figure 4 The N2 adsorption-desorption curves of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention are shown.

[0031] Figure 5 The image shows the pore size distribution of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention.

[0032] Figure 6 Cyclic voltammetry curves of the deionization electrode prepared from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention.

[0033] Figure 7 Cyclic voltammetry curves of the capacitive deionization electrode prepared from the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) and mycelial biochar (FBC) of this invention at different scan rates.

[0034] Figure 8 The specific capacitance-CV scan rate curves of the capacitor deionization electrode made from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention are shown.

[0035] Figure 9 The constant current charge-discharge diagrams are shown for the capacitive deionization electrodes made from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention.

[0036] Figure 10 Electrochemical impedance spectroscopy of the deionization electrode prepared from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention.

[0037] Figure 11 The conductivity-time curves of the capacitive deionization device constructed with the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention are shown.

[0038] Figure 12 The electroadsorption capacity versus time curves of the capacitive deionization device constructed with the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention when desalinating chlorine-containing wastewater.

[0039] Figure 13 The graph shows the change curves of electroadsorption rate and electroadsorption capacity when the capacitive deionization device constructed with the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention is used to desalinate chlorine-containing wastewater.

[0040] Figure 14 The figures show the 30-cycle charge-discharge curves of the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) of this invention, and the 30-cycle adsorption-desorption electroadsorption diagrams corresponding to the removal of chlorine-containing wastewater by the capacitor deionization device constructed from it. Detailed Implementation

[0041] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0042] Example 1

[0043] A method for preparing a CoFe-LDH composite mycelial biochar electrode material includes:

[0044] (1) Preparation of mycelial biochar (FBC)

[0045] Glucose (10g), peptone (2.5g), yeast extract (1g), MgSO4 (0.25g), and KH2PO4 (0.5g) were dissolved in 500mL of deionized water, then autoclaved at 121℃ for 30min, and cooled to room temperature under aseptic conditions. For inoculation, 5mL of Aspergillus niger spore suspension was aseptically transferred to the above-mentioned sterilized culture medium. The resulting culture was then placed in a temperature-controlled shaker and continuously stirred at 150rpm for 7 days at 28±1℃ to promote growth. Mycelial growth; After filtering the obtained Aspergillus niger mycelia, soak them in anhydrous ethanol to remove residual impurities, and then rinse them thoroughly with deionized water until the supernatant reaches a neutral pH (7.0±0.2); The washed Aspergillus niger mycelia are freeze-dried in a freeze dryer at -80℃ for 24h to ensure complete dehydration. The freeze-dried Aspergillus niger mycelia are placed in a tube furnace and pyrolyzed at a heating rate of 5℃ / min to 700℃ under N2 protection and then held for 2h to obtain the mycelial biochar (FBC).

[0046] (2) Preparation of CoFe-LDH composite mycelial biochar electrode material

[0047] Fe(NO3)3·9H2O (0.404 g), Co(NO3)2·6H2O (0.58 g), NH4F (0.25 g), and urea (1.2 g) were dissolved in 60 mL of deionized water under strong magnetic stirring at 25 °C until a transparent and homogeneous CoFe-LDH nanosheet precursor solution was formed. Then, 100 mg of mycelial biochar (FBC) was added to the above solution and stirred and dispersed for 30 min to ensure uniform interaction between FBC and the CoFe-LDH nanosheet precursor. The resulting suspension was then... The liquid was transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and subjected to hydrothermal treatment at 120 °C for 10 h in an oven to allow CoFe-LDH nanosheets to grow in situ on the FBC surface. After natural cooling to room temperature, the product was collected by centrifugation and filtration, and then washed repeatedly with anhydrous ethanol and deionized water to remove unreacted substances. The washed composite material was then dried overnight in a vacuum oven at 60 °C to obtain the CoFe-LDH composite mycelial biochar electrode material, denoted as FBC / CoFe-LDH1.

[0048] In this embodiment, the obtained CoFe-LDH composite mycelial biochar electrode material includes CoFe-LDH nanosheets and mycelial biochar. The CoFe-LDH nanosheets grow vertically on the inner and outer walls of the mycelial biochar, forming a two-dimensional and three-dimensional network structure. 2+ / Fe 3+ The molar ratio is 2:1.

[0049] In this embodiment, other different Co samples were also prepared. 2+ / Fe 3+ The preparation method of the CoFe-LDH composite mycelial biochar electrode material with the specified ratio is basically the same as that of the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH1) mentioned above, except that: in step (2), the amount of Co(NO3)2·6H2O is 0.87g and 1.16g respectively, and the corresponding CoFe-LDH composite mycelial biochar electrode materials are named as FBC / CoFe-LDH2 and FBC / CoFe-LDH3 respectively. In the CoFe-LDH composite mycelial biochar electrode materials FBC / CoFe-LDH2 and FBC / CoFe-LDH3, Co 2+ / Fe 3+ The molar ratios are 3:1 and 4:1, respectively.

[0050] Figure 1 The XRD patterns of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3), CoFe-LDH2, and mycelial biochar (FBC) of the present invention are shown. The CoFe-LDH nanosheets (CoFe-LDH2) are prepared according to the above-mentioned preparation method of FBC / CoFe-LDH1, except that the amount of Co(NO3)2·6H2O in step (2) is 0.87g and the addition of FBC is omitted, so as to obtain CoFe-LDH nanosheets, which are denoted as CoFe-LDH2.

[0051] from Figure 1 It can be seen that the CoFe-LDH composite mycelial biochar electrode materials all exhibit almost identical diffraction peaks, namely, obvious peaks at 11.7°, 23.4°, 34.1°, 36.6°, 38.7°, 43.3°, 46.2°, 59.1°, and 60.5°, which correspond to the (003), (006), (012), (104), (015), (107), (018), (110), and (113) crystal planes of CoFe-LDH2, indicating the successful preparation of the electrode material. However, compared with CoFe-LDH2 (11.99°), the (003) crystal plane diffraction peak of FBC / CoFe-LDH shifts to 11.71°, and the interlayer spacing increases from 0.738 nm to 0.755 nm. The increase in interlayer spacing is beneficial to the diffusion of ions in the electrochemical process. It is worth noting that the electrode material retains the inherent graphite characteristics of the biochar matrix (as evidenced by the broad carbon peak at ~25°) while incorporating the unique crystal structure of LDH. This synergistic structure helps to enhance charge transfer kinetics, which is crucial for optimizing the electrochemical performance and desalination efficiency of the electrode material.

[0052] Figure 2 The images show SEM images of the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2), CoFe-LDH nanosheets (CoFe-LDH2), and mycelial biochar (FBC) of this invention, as well as a TEM image of FBC / CoFe-LDH2. Figure 2 As shown in figure a, the original mycelial biochar (FBC) exhibits a fibrous microstructure with an average diameter of 2-3 micrometers; in contrast, CoFe-LDH2 displays a typical layered morphology. Figure 2 b); In FBC / CoFe-LDH2, a large number of LDH nanosheets are uniformly anchored on the fibrous FBC framework. Figure 2 c) A hierarchical heterogeneous structure is formed. This engineered structure not only reduces interlayer aggregation of LDH nanosheets and enhances structural stability, but also exposes abundant redox active sites and optimizes ion diffusion pathways, thereby improving electrode durability and desalination efficiency. TEM image of FBC / CoFe-LDH2 ( Figure 2 d) shows that CoFe-LDH has typical two-dimensional layered features, with long fibrous structures corresponding to FBC; high-resolution transmission electron microscopy (HRTEM) images confirm that its lattice spacing is 0.19 nm, which matches the (014) crystal plane of CoFe-LDH; Figure 2 g-2h also showed the EDS energy spectrum of FBC / CoFe-LDH2, while elemental distribution analysis further showed that C, O, Fe and Co elements were uniformly distributed in the composite material, confirming the successful composite of CoFe-LDH nanosheets and FBC.

[0053] Figure 3 These are FTIR images of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention. Figure 3 It can be seen that -OH (3445cm) was detected in the CoFe-LDH composite mycelial biochar electrode material. -1 C = C(1626cm) -1 CO3 2- (1356cm -1 C = O (1099cm) -1 ), Co-OH (758cm) -1 ) and Fe-O (514cm -1 Characteristic peaks such as ) and ) are consistent in the infrared spectrum of these functional groups CoFe-LDH, which not only confirms the existence of CoFe-LDH structure in the electrode material, but also verifies the successful synthesis of the electrode material.

[0054] Figure 4 and Figure 5 The N2 adsorption-desorption curves and pore size distribution diagrams of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) of this invention are shown. Figure 4 , 5 It can be seen that both FBC and FBC / CoFe-LDH electrode materials exhibit type IV isotherms and obvious H3 hysteresis loops, confirming their mesoporous structure. Furthermore, the pore size distribution of all samples falls within the mesoporous range (2-100 nm), indicating that well-developed mesopores are beneficial for Cl... - Adsorption.

[0055] In this embodiment, the specific surface area, pore volume, and pore size of the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) were also tested, and the results are shown in Table 1.

[0056] Table 1. BET test results of different samples

[0057]

[0058] As shown in Table 1 above, compared with FBC (1.867m) 2 g -1 ), FBC / CoFe-LDH1 (14.114m 2 g -1 ) and FBC / CoFe-LDH3 (13.367m 2 g -1 Compared to FBC / CoFe-LDH2, FBC / CoFe-LDH2 has the highest specific surface area (14.318 m²). 2 g -1 Furthermore, FBC / CoFe-LDH2 also has a large pore volume; these results indicate that a high specific surface area, well-developed mesopores, and increased pore volume are beneficial for efficient ion transport.

[0059] Example 2

[0060] The application of a CoFe-LDH composite mycelial biochar electrode material in the preparation of capacitive deionization electrodes includes:

[0061] Weigh out 80 mg each of the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and mycelial biochar (FBC) described in Example 1, add 10 mg of conductive carbon black and 10 mg of PVDF and mix evenly. Then slowly add N-methylpyrrolidone and stir continuously to form a uniform slurry. Spread the slurry on a graphite plate (5 cm × 5 cm) with a trowel and vacuum dry for 12 h to obtain the capacitor deionization electrode.

[0062] The capacitor deionization electrode prepared in this embodiment was cut into a 1cm×1cm square as the working electrode, the silver / silver chloride electrode as the reference electrode, and the platinum sheet electrode as the counter electrode. A 1M NaCl solution was used as the electrolyte, and electrochemical performance tests such as cyclic voltammetry, constant current charge-discharge, and electrochemical impedance spectroscopy were performed using an electrochemical workstation.

[0063] Figure 6 This image shows the cyclic voltammetry curves of the deionization capacitors prepared from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) of this invention. Figure 6 It can be seen that all CV curves are quasi-rectangular in shape, with no obvious redox peaks, indicating that they have a low affinity for Cl. - The adsorption is mainly pseudocapacitive.

[0064] Figure 7 This image shows the cyclic voltammetry curves of a capacitive deionization electrode prepared from the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) of this invention at different scan rates. Figure 7 It can be seen that when the scan rate increases from 1 mV / s to 50 mV / s, the CV curve shape of the capacitive deion electrode prepared by the CoFe-LDH composite mycelial biochar composite electrode material (FBC / CoFe-LDH2) remains basically unchanged. This proves that the capacitive deion electrode prepared by the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) has good rate performance and good cycle stability.

[0065] Figure 8 This image shows the specific capacitance-CV scan rate curves of the capacitive deionization electrodes prepared from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) of this invention. Figure 8 It can be seen that the specific capacitance calculated from the CV curves obtained at different scanning speeds is at 30mV s.-1 At the specified scan rate, the specific capacitance of the FBC / CoFe-LDH2 electrode reached 140.71 F g. -1 It is significantly better than FBC (84.26F g). -1 ), FBC / CoFe-LDH1 (128.48F g) -1 ) and FBC / CoFe-LDH3 (138.09F g) -1 Among them, the capacitive deionization electrode prepared by FBC / CoFe-LDH2 showed the best specific capacitance, indicating that the electrode prepared by CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) has excellent capacitive performance.

[0066] Figure 9 This image shows the constant current charge-discharge diagrams of capacitive deionization electrodes made from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) of this invention. Figure 9 It can be seen that, compared with the capacitive deionization electrode prepared by fungal mycelial biochar (FBC), the capacitive deionization electrode prepared by CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) has a longer discharge time; among them, the capacitive deionization electrode prepared by FBC / CoFe-LDH2 has the longest discharge time, which indicates that the electrode prepared by CoFe-LDH composite mycelial biochar composite electrode material (FBC / CoFe-LDH2) has a higher specific capacitance, which is consistent with the results of the CV curve.

[0067] Figure 10 Electrochemical impedance spectroscopy (EIS) spectra of capacitive deionization electrodes prepared from the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) of this invention. Figure 10 It can be seen that the capacitive deionization electrode prepared from the CoFe-LDH composite mycelial biochar composite electrode material (FBC / CoFe-LDH2) exhibits a relatively small semicircle, corresponding to the smallest charge transfer resistance; this indicates that in Cl... - During the removal process, less energy is lost due to internal resistance, resulting in higher charging efficiency.

[0068] Example 3

[0069] An application of a CoFe-LDH composite mycelial biochar electrode material in capacitive deionization of chloride ions in wastewater includes:

[0070] (1) Weigh 80 mg each of the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) described in Example 1, add 10 mg of conductive carbon black and 10 mg of polyvinylidene fluoride (PVDF), grind evenly, then slowly add N-methylpyrrolidone, stirring constantly to form a uniform slurry, then coat it on a graphite plate (5cm×5cm), vacuum dry for 12h to obtain a capacitor deionization electrode;

[0071] (2) The above-mentioned capacitor deionization electrode is used as the anode and the activated carbon electrode is used as the cathode to assemble the capacitor deionization device. The preparation method of the activated carbon cathode electrode is basically the same as that of the capacitor deionization electrode, except that activated carbon is used to replace the CoFe-LDH composite mycelial biochar electrode material.

[0072] In this step, the capacitor deionization device mainly includes an activated carbon cathode and a capacitor deionization electrode anode, as well as an acrylic plate, a silicone pad, an activated carbon cathode, a silicone pad, a diaphragm, a capacitor deionization electrode anode, a silicone pad, and an acrylic plate stacked sequentially along the water inlet direction. The activated carbon cathode and the capacitor deionization electrode anode are connected to a DC power supply.

[0073] (3) The above-mentioned capacitor deionization device was used to carry out desalination experiment on chlorine-containing wastewater. Specifically, 100 mL of NaCl solution with an initial concentration of 1000 mg / L was used as chlorine-containing wastewater. Dechlorination was carried out under the conditions of influent flow rate of 10 mL / min and applied voltage of 1.2 V to complete the purification of chlorine-containing wastewater.

[0074] Figure 11 The graph shows the conductivity-time variation curves of a capacitive deionization device constructed using the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) of this invention for desalinating chlorinated wastewater. Figure 11 It can be seen that the conductivity of the capacitive deionization electrode prepared by FBC / CoFe-LDH2 decreased the most, which indicates that FBC / CoFe-LDH2 has the greatest chloride ion removal capacity.

[0075] Figure 12The graph shows the electroadsorption capacity versus time variation curves of a capacitive deionization device constructed using the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) of this invention for desalinating chlorine-containing wastewater. Figure 12 It can be seen that, as the electroadsorption process proceeds, the electrodes in the four CDI cells reach adsorption saturation within 30 minutes, after which the adsorption amount stabilizes; notably, FBC / CoFe-LDH2 shows the highest SAC (89.6 mg g). -1 ), respectively exceeding FBC (22.4 mg g) -1 ), FBC / CoFe-LDH1 (53.2 mg g) -1 ) and FBC / CoFe-LDH3 (72.8 mg g) -1 The electroadsorption capacity was 4 times, 1.68 times, and 1.23 times that of the CoFe-LDH composite mycelial biochar composite electrode material (FBC / CoFe-LDH2), indicating that the CoFe-LDH composite mycelial biochar composite electrode material has excellent electroadsorption performance.

[0076] Figure 13 The graph shows the change in electroadsorption rate versus electroadsorption capacity when a capacitive deionization device constructed using the CoFe-LDH composite mycelial biochar electrode materials (FBC / CoFe-LDH1, FBC / CoFe-LDH2, FBC / CoFe-LDH3) and fungal mycelial biochar (FBC) is used to desalinate chlorinated wastewater. Figure 13 It can be seen that the electroadsorption rate-electroadsorption amount variation curve of the capacitive deionization device constructed from CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) is generally located at the upper right, indicating that FBC / CoFe-LDH2 has the highest electroadsorption amount and the fastest electroadsorption desalination rate.

[0077] Figure 14 This image shows the 30-cycle charge-discharge curve of the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) of this invention, and the 30-cycle adsorption-desorption electroadsorption diagram of the capacitive deionization device constructed from it when removing chlorine-containing wastewater. Figure 14 It can be seen that Cl - The adsorption capacity is only 89.6 mg g -1 Slightly decreased to 83.1 mg g -1(After 30 cycles); In addition, its specific capacitance remains almost unchanged after 30 charge-discharge cycles, which indicates that the capacitive deion electrode prepared by the CoFe-LDH composite mycelial biochar composite electrode material (FBC / CoFe-LDH2) has excellent cycle stability and high sodium chloride removal efficiency. It is a novel capacitive deion anode that is highly efficient and can be used for a long time, and has good application prospects.

[0078] In this embodiment, the treatment effect of a capacitor deionization device assembled under the same conditions using existing LDH-based electrode materials on chlorine-containing wastewater was also compared, as shown in Table 2 below.

[0079] Table 2. Performance comparison of FBC / CoFe-LDH2 with other LDH-based electrode materials

[0080]

[0081]

[0082] Table 2 above shows the synthesis of an electrode material (CNFs@LDH) for CDI dechlorination, synthesized by coating NiMn-LDH onto the surface of carbon nanofibers (CNFs). The maximum adsorption capacity was 72.06 mg g. -1 .

[0083] The literature (“Enhanced Pseudo-Capacitance Process in Nanoarchitectural Layered Double Hydroxide Nanoarrays Hollow Nanocages for Improved Capacitive Deionization Performance”, ACS Applied Materials & Interfaces, Vol. 15, 2023) discloses a method for designing a three-dimensional (3D) hollow nanocage structure (C / CoNi-LDH) of a CoNi layered double hydroxide / carbon composite material as a CDI anode using a pre-carbonized ZIF-67 template via cation etching, achieving a maximum chloride ion adsorption capacity of 60.88 mgg.-1 .

[0084] The literature (“Layered Metal Oxide Nanosheets with Enhanced Interlayer Space for Electrochemical Deionization”, Advanced Materials, 2023, Issue 35) discloses the synthesis of sodium dodecyl sulfate (SDS) intercalated CoAl-LDH nanosheets (CoAl-LMO-SDS), with the interlayer spacing increased from 0.76 nm to 1.33 nm, and used as a CDI anode for dechlorination, with a maximum dechlorination capacity of 31.78 mg / g.

[0085] The literature (“Rational design of LDH-Derived NiFe layered double oxides ascapacitive deionization anode for efficient chlorine ion storage with 'amemory effect'”, Applied Surface Science, Vol. 687, 2025) discloses the synthesis of NiFe-LDO / C composite material (NiFe-LDO / C) as a CDI anode by heat-treating NiFe-LDH / MOF derived from metal-organic frameworks (MOFs). The highest chloride ion adsorption capacity reached 55.72 mg g. -1 .

[0086] The literature (“Promoting the uptake of chloride ions by ZnCo-Cl layered doublehydroxide electrodes for enhanced capacitive deionization”, Environmental Science: Nano, Vol. 8, 2021) discloses the preparation of chloride ion-intercalated ZnCo-LDH nanosheets (ZnCo-LDH) as CDI dechlorination anodes by intercalating chloride ions into ZnCo-LDH sheets, with a maximum adsorption capacity of 56.1 mg g. -1 .

[0087] The literature (“Flexible structural engineering of PPy-NiCo-LDH@Mxene for improved capacitive deionization and efficient hard water softening process”, Separation and Purification Technology, Vol. 280, 2022) discloses the integration of PPy, NiCo-LDH and Mxene via a hydrothermal method to construct an efficiently designed Mxene-based three-dimensional PPy-NiCo-LDH@Mxene composite material (PPy / rGO / Ni-Co LDH) for CDI anode dechlorination, with a maximum adsorption capacity of 31.5 mg g. -1 .

[0088] The literature (“Vertically-aligned growth of CuAl-layered double oxides on reduced graphene oxide for hybrid capacitive deionization with superior performance”, Environmental Science: Nano, Vol. 7, 2022) discloses the synthesis of a vertically aligned CuAl-layered double oxide (CuAl-LDO / rGO) grown on reduced graphene oxide (CuAl-LDO / rGO), which, as a high-performance anode for CDI, achieved an optimal CDI dechlorination effect of 64 mg / g. -1 .

[0089] The literature (“Elaborate designed sandwich structural faradic material NPC / NiMn-LDH / MXene for enriched ion accessible transfer pathways in capacitive deionization”, Chemical Engineering Journal, 2024, Vol. 484) discloses a composite material (NPC / NiMn-LDH / MXene) constructed by dispersing flower-shaped NiMn-LDH nanosheets within an MXene nanosheet sandwich structure using nitrogen-doped porous carbon spheres (NPC) as a conductive intermediate. This composite material serves as the anolyte for CDI dechlorination, achieving a maximum adsorption capacity of 34.2 mg / g. -1 .

[0090] The literature (“Controllable synthesis of a hollow core-shell Co-Fe layered double hydroxide derived from Co-MOF and its application in capacitive deionization”, Journal of Colloid and Interface Science, 2021, Vol. 585) discloses a strategy of simultaneously growing Co / Fe-LDH on the surface of a Co-MOF precursor to synthesize a hollow core-shell Co-MOF@Fe / Co-LDH (Co-Fe-LDH) material for CDI desalination, with a maximum dechlorination capacity of 34.2 mg g. -1 .

[0091] In this invention, the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) synthesized in Example 1 was used as the anode for CDI dechlorination, and its maximum adsorption capacity reached as high as 89.6 mg / g. In comparison, with the other synthesis conditions unchanged, except that the FBC was replaced with the same amount of straw biochar, a CoFe-LDH composite straw biochar electrode material (BC / CoFe-LDH2) was synthesized for CDI dechlorination, and its maximum adsorption capacity was only 53.2 mg / g. -1 .

[0092] As can be seen from the above, the CoFe-LDH composite mycelial biochar electrode material (FBC / CoFe-LDH2) exhibits excellent dechlorination capability, outperforming most existing LDH-based materials. This performance improvement can be attributed to three key factors: (1) the optimized interfacial interaction between FBC and CoFe-LDH ensures full exposure of active sites, effectively promoting ion storage; (2) the three-dimensional interconnected network structure of FBC / CoFe-LDH2 provides continuous channels for charge and ion transport, significantly improving kinetic performance and overall efficiency; and (3) the synergistic coupling effect between CoFe-LDH and FBC further enhances the electrochemical activity and desalination performance of the composite material.

[0093] In summary, this invention innovatively develops an electrode material based on CoFe-LDH composite mycelial biochar. By synergistically integrating the double-layer adsorption characteristics of fungal mycelial biochar with the intercalation pseudocapacitive adsorption advantages of CoFe-LDH, a novel electrode system with vertical ion transport channels is constructed. This material exhibits superior performance in the treatment of chlorine-containing wastewater, specifically: excellent conductivity, high specific surface area, rapid ion diffusion kinetics, outstanding capacitance, and efficient desalination performance, while also possessing low energy consumption, high cycle stability, and good charging efficiency. Regarding the preparation process, the method of this invention cleverly preserves the intrinsic properties of each component, achieving material performance optimization through a simple synthesis route. This process has the following outstanding advantages: low chemical reagent usage, low production cost, good energy consumption control, short preparation cycle, and precise control of interface structure, making it very suitable for industrial-scale production. The capacitive deionization electrode system prepared based on this composite material, through optimized combination with conductive carbon black and binders, exhibits multiple technical advantages: excellent interfacial contact characteristics, superior capacitance performance, high conductivity, and stable cycle life. When used as an anode in the treatment of chlorine-containing wastewater, this system exhibits significant technical and economic advantages: simple operation process, low energy consumption, economical equipment cost, easy transportation and installation, while maintaining stable desalination efficiency and long service life, making it a promising candidate for industrial wastewater treatment.

[0094] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a CoFe-LDH composite mycelial biochar electrode material, characterized in that, include: Using mycelial biochar as a carrier, CoFe-LDH nanosheets were vertically grown on the inner and outer walls of the mycelial biochar via an in-situ hydrothermal method, thus obtaining the CoFe-LDH composite mycelial biochar material.

2. The preparation method of the CoFe-LDH composite mycelial biochar electrode material according to claim 1, characterized in that, The mycelial biochar is Aspergillus niger mycelial biochar, which is prepared by the following method: S1. Prepare a liquid culture medium containing glucose, peptone, yeast powder, magnesium sulfate and potassium dihydrogen phosphate. Inoculate the Aspergillus niger spore suspension into the liquid culture medium and culture it to obtain Aspergillus niger mycelium. S2. After filtering the Aspergillus niger mycelium, wash, dry, and then pyrolyze it under an inert gas to obtain the mycelial biochar.

3. The preparation method of the CoFe-LDH composite mycelial biochar electrode material according to claim 2, characterized in that, In step S1, the liquid culture medium includes: glucose 10-30 g / L, peptone 1-10 g / L, yeast extract 1-5 g / L, magnesium sulfate 0.1-1 g / L and potassium dihydrogen phosphate 0.1-2 g / L.

4. The preparation method of the CoFe-LDH composite mycelial biochar electrode material according to claim 2 or 3, characterized in that, In step S2, the pyrolysis temperature is 500-700℃, and the heating rate is 1-10℃ / min.

5. The preparation method of the CoFe-LDH composite mycelial biochar electrode material according to any one of claims 1-4, characterized in that, The in-situ hydrothermal method specifically includes: Iron source, cobalt source, ammonium fluoride and urea are dissolved in water, and the mycelial biochar is added and mixed. After the mixture is homogenized, a hydrothermal reaction is carried out. CoFe-LDH nanosheets are grown in situ on the surface of the mycelial biochar, thus obtaining the CoFe-LDH composite mycelial biochar electrode material.

6. The preparation method of the CoFe-LDH composite mycelial biochar electrode material according to claim 5, characterized in that, The iron source is at least one of ferric nitrate, ferric chloride, ferric sulfate and their hydrates, and the cobalt source is at least one of cobalt nitrate, cobalt chloride, cobalt sulfate and their hydrates; Preferably, the molar ratio of the iron source, cobalt source, ammonium fluoride, and urea is 1:2-4:4-8:10-30; Preferably, the mass ratio of the iron source to mycelial biochar is 3-6:

1.

7. The method for preparing the CoFe-LDH composite mycelial biochar electrode material according to claim 5 or 6, characterized in that, The hydrothermal reaction temperature is 100-120℃, and the time is 6-12h.

8. A CoFe-LDH composite mycelial biochar electrode material prepared by the preparation method according to any one of claims 1-7.

9. The application of the CoFe-LDH composite mycelial biochar electrode material as described in claim 8 in capacitive deionization dechlorination.

10. The application of the CoFe-LDH composite mycelial biochar electrode material according to claim 9 in capacitive deionization dechlorination, characterized in that, The CoFe-LDH composite mycelial biochar electrode material is mixed with a conductive agent, a binder, and a solvent to form an anode slurry, which is then coated onto the surface of a conductive carrier and dried to form an anode. The components, including the anode, are assembled into a capacitor deionization desalination device, which is then used for capacitor deionization dechlorination. Preferably, the mass ratio of the CoFe-LDH composite mycelial biochar electrode material, the conductive agent, and the binder is 7-8:1:1-2; Preferably, the adhesive is at least one of polyvinylidene fluoride, polytetrafluoroethylene, or polyvinyl alcohol; the solvent is at least one of 1-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide; and the conductive carrier is at least one of graphite plate, nickel foam, copper foil, or titanium mesh.

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