A lignin-activated carbon capacitor deionization anode electrode material, its preparation method and application

Abstract

This invention discloses a lignin-activated carbon capacitive deionization anode electrode material, its preparation method, and its application, belonging to the field of capacitive deionization technology. The method includes the following steps: (1) preparing a corresponding composite material based on the composition of the lignin-activated carbon capacitive deionization anode electrode material; (2) carbonizing the composite material; and (3) obtaining the lignin-activated carbon capacitive deionization anode electrode material. This method has the advantages of convenient processing, low raw material cost and wide availability, and environmental friendliness. The prepared lignin-activated carbon capacitive deionization anode electrode material has the characteristics of good stability, long service life, and high adsorption capacity, and has good prospects in the field of capacitive deionization and desalination.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of capacitive deionization, in particular to a lignin activated carbon capacitive deionization anode electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid growth of population and the rapid development of economy, the problem of water resource shortage is becoming more and more prominent, and has become one of the core problems to be solved at present. Efficient and energy-saving desalination technology is an effective measure to solve the problem of fresh water shortage. Capacitive deionization technology has become one of the most promising desalination technologies due to its low energy consumption, simple device, green environmental protection and other advantages. However, the production cost of the current capacitive deionization electrode is high, the types of anode materials are few, and the adsorption capacity is relatively low, which restricts the development of this type of desalination technology.

[0003] In one aspect, for materials that realize chloride ion storage through conversion reaction, such as Ag / AgCl, Bi / BiOCl, etc., due to the large adsorption capacity, it is beneficial to improve the adsorption performance of the anode to chloride ions, so as to improve the overall desalination capacity of the hybrid capacitive deionization. However, the conversion reaction will cause a large volume expansion, which will cause the capacity to decay after a number of cycles, which is not conducive to its actual production and application, and is one of the problems to be solved in the current capacitive deionization technology.

[0004] For example, the Chinese invention patent with publication number CN112062229A discloses a Bi / MOF derived porous carbon sphere composite material and its preparation method and application. The Bi / MOF derived porous carbon sphere composite material is prepared by loading nano-sized metal Bi particles on the surface of N-doped MOF derived porous carbon spheres. The Bi / MOF derived porous carbon sphere composite material of the invention can effectively alleviate the volume expansion problem of Bi in the redox process by anchoring nano-sized metal Bi particles on the MOF derived carbon, thereby enhancing the stability of the electrode material and reducing the electrode pulverization phenomenon. In the preparation process, N-doped MOF derived porous carbon compounds are prepared, and a reducing agent is used to reduce bismuth oxide to form a Bi / MOF derived porous carbon sphere composite material, which makes the process more complex. In order to form a spherical morphology, zinc salt or iron salt is used in the preparation process. Due to the involvement of the crystallization kinetics of metal elements, the obtained pore structure is often disordered and irregular. Therefore, the synthesis process of the MOF material requires high precision control of pore size, density and distribution, which also increases the difficulty and cost of production.

[0005] In another aspect, the raw materials of the electrode materials at the present stage are mostly from fossil raw materials, which have high cost and complex preparation process. Therefore, it is a trend to replace fossil energy materials with renewable biomass materials. Lignin, as a renewable biomass material, has the advantages of wide source and low cost, with content only second to cellulose. Therefore, it is of great significance to reduce cost and waste resources to seek a suitable process to use lignin in the field of capacitive deionization.

[0006] For example, the Chinese invention patent with publication number CN115463625A provides a silver nanowire-lignin-derived carbon composite aerogel and its preparation method and application. The silver nanowire is wrapped in lignin by using the method of rapid freezing, avoiding the agglomeration of silver nanowire. The unique adhesion, dispersibility and chelation of lignin uniformly disperse silver nanowire and form an interconnected network structure. The solvent is removed by freeze-drying to form a loose porous mesoporous structure, obtaining more active sites for ion adsorption, which has good application prospect in the field of capacitive deionization. However, the silver nanowire required by this scheme has strict product control requirements in the industry (such as polyol method, electrochemical method, vapor deposition method, template method, etc.). It is currently difficult to obtain through a universal and simple way, and the preparation cost is still at a high level. In addition, the bonding force between the functional material and the substrate in the wrapped form is insufficient, and the electrode material in the form of flexible film composed of aerogel and two-dimensional nanomaterials also has technical problems such as insufficient mechanical strength, suboptimal physicochemical stability, and short service life, which has poor applicability in capacitive deionization, membrane capacitive deionization, and double-ion electrochemical deionization based on electrochemical capture of ions. Capacitive deionization devices, which further limits its application in the field of capacitive deionization.

[0007] In summary, a lignin activated carbon capacitive deionization anode electrode material and a preparation method thereof are provided, which have low raw material cost, are environmentally friendly, have good stability, long service life, and high adsorption capacity, solve the above technical problems, and have positive significance for promoting the development of desalination technology. SUMMARY

[0008] In view of the above-mentioned defects of the prior art, in the first aspect of the present application, a preparation method of a lignin activated carbon capacitive deionization anode electrode material is provided, which is convenient in process, low in raw material cost, widely sourced, and environmentally friendly, comprising the following steps:

[0009] (1) According to the components of the lignin activated carbon capacitive deionization anode electrode material, the corresponding composite material is prepared:

[0010] a. Mix lignin, Bi precursor or Ag precursor with solvent, and dialyze the resulting mixture in water to complete solvent exchange, and recover the corresponding Bi@lignin composite material or Ag@lignin composite material.

[0011] b. The lignin, Ag precursor and solvent are mixed and the resulting mixture is dialyzed in an aqueous chloride solution to complete solvent exchange and recover the AgCl@lignin composite material;

[0012] c. Mix lignin, Bi precursor, chloride salt and solvent, and then carry out hydrothermal reaction; after the hydrothermal reaction is completed, recover to obtain BiOCl@lignin composite material;

[0013] Bi precursor, Ag precursor, and chloride salt are salts that are soluble in solvents and ionize.

[0014] (2) Carbonization of composite materials:

[0015] Bi@lignin composite material, Ag@lignin composite material, AgCl@lignin composite material, and BiOCl@lignin composite material were carbonized by calcination under an inert atmosphere to obtain Bi@lignin activated carbon anode material, BiOCl@lignin activated carbon anode material, Ag@lignin activated carbon anode material, and AgCl@lignin activated carbon anode material, respectively.

[0016] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0017] The lignin activated carbon capacitor deionization anode electrode material includes at least one of Bi@lignin activated carbon anode material, BiOCl@lignin activated carbon anode material, Ag@lignin activated carbon anode material, and AgCl@lignin activated carbon anode material.

[0018] Lignin is an abundant renewable resource, widely found in plant cell walls, especially as a byproduct in industries such as papermaking. Due to its wide availability and low cost, lignin can reduce dependence on fossil fuels during production, thereby lowering production costs. The lignin used in this invention comes from various sources, such as alkali lignin, eucalyptus pectin, high-boiling-point alcohol lignin, organic solvent lignin, sulfate lignin, and enzymatically hydrolyzed lignin, all commonly used in industrial production. Those skilled in the art can select the appropriate type based on actual conditions.

[0019] Preferably, in step (1), the lignin includes at least one of alkali lignin, eucalyptus pectin, high-boiling alcohol lignin, organic solvent lignin, sulfate lignin, and enzymatically hydrolyzed lignin.

[0020] Bi precursors and Ag precursors are selected from suitable salts that can dissolve and ionize in a solvent environment. Based on this principle and considering the source and cost of raw materials, Bi precursors can be selected from organic or inorganic salts of bismuth such as bismuth nitrate, bismuth chloride, bismuth sulfate, bismuth acetate, bismuth citrate, bismuth iodide, bismuth bromide, and bismuth phosphate; Ag precursors can be selected from organic or inorganic salts of silver such as silver nitrate, silver acetate, silver phosphate, and silver trifluoroacetate.

[0021] Preferably, in step (1), the Bi precursor includes bismuth salts and their hydrates, and the bismuth salts include at least one of bismuth nitrate, bismuth chloride, bismuth sulfate, bismuth acetate, bismuth citrate, bismuth iodide, bismuth bromide, and bismuth phosphate.

[0022] Preferably, in step (1), the Ag precursor includes silver salt and its hydrate, and the silver salt includes at least one of silver nitrate, silver acetate, silver phosphate, and silver trifluoroacetate.

[0023] Based on the selection of Bi precursors, Ag precursors, and chloride salts and their solubility characteristics, those skilled in the art can choose appropriate solvents and dosages. Furthermore, some organic solvents can be recovered and recycled through methods such as rotary evaporation, further reducing production costs.

[0024] Preferably, in step (1), the solvent includes at least one of tetrahydrofuran, ethanol, ethylene glycol, acetone, dimethyl sulfoxide, dichloromethane, and water.

[0025] The ratio of functional materials to lignin in the anode material should be appropriately controlled within a suitable range, as this ratio affects the anode's electrochemical performance, structural stability, and compatibility with the electrolyte. Functional materials made from Bi and Ag precursors provide active sites for electrochemical reactions, while the carbonized structure of lignin provides mechanical support and electronic conduction pathways. If the proportion of functional materials is too high, it may lead to anode structural instability, making it prone to volume expansion and pulverization. If the proportion of functional materials is too low, it may not provide enough active sites, limiting the battery's capacity and efficiency.

[0026] Preferably, in step (1), the mass ratio of Bi precursor or Ag precursor to lignin is 0.2-2:1.

[0027] The chloride salts selected are also suitable salts that can dissolve and ionize in a solvent environment. Sodium chloride and potassium chloride are particularly suitable for the chloride salts prepared in this invention due to their wide availability and low cost. Due to the limitations of reaction kinetics, in order to obtain the target AgCl or BiOCl, it is advisable to add chlorine element slightly higher than the stoichiometric amount during the preparation process to make the reaction of the raw materials more complete, which is beneficial to improving the quality and performance of the product.

[0028] Preferably, in step (1), the chloride salt includes at least one of sodium chloride and potassium chloride.

[0029] Preferably, in step (1), the concentration of the aqueous solution of chloride salt is 1-20 mM.

[0030] Preferably, in step (1), the ratio of Bi atoms or Ag atoms in the Bi precursor or Ag precursor to chlorine atoms in the chloride salt is 1-20:1.

[0031] The molecular weight of lignin for dialysis is selected based on the molecular weight of lignin from different sources, so that the lignin is retained and completes self-assembly in the dialysis device (such as a dialysis bag).

[0032] Preferably, in step (1), the molecular weight of the dialysis sample is 1-12 KD.

[0033] Preferably, in step (1), the hydrothermal reaction temperature is 160 °C and the reaction time is 24 h.

[0034] Preferably, in step (2), the calcination temperature is 400-1000℃ and the calcination time is 0.5-3 h.

[0035] In a second aspect of the present invention, a lignin activated carbon capacitor deionization anode electrode material with good stability, long service life and high adsorption capacity is provided, which is prepared by the method of the first aspect of the present invention.

[0036] In a third aspect of the invention, an application of the lignin activated carbon capacitor deionization anode electrode material of the second aspect of the invention is provided, specifically its application as an anode material in capacitor deionization and desalination.

[0037] Preferably, the method of application includes the following steps: mixing lignin activated carbon capacitor deionization anode electrode material with a conductive agent, a binder, and a solvent to form an anode slurry, which is then coated onto the surface of a current collector and dried to form an anode; assembling the components including the anode to obtain a capacitor deionization desalination device for capacitor deionization desalination.

[0038] More preferably, the mass ratio of the lignin activated carbon capacitor deionization anode electrode material, conductive agent, and binder is 5-12:1:1.

[0039] The conductive agent, binder, and solvent can be made from materials commonly used in the art, and those skilled in the art can select appropriate combinations according to actual needs. For example, common binders such as polyvinylidene fluoride (PVDF) can be used, conductive agents such as conductive carbon black that enhances the conductivity of the electrodes can be used, and solvents such as N-methylpyrrolidone (NMP) are usually used. There are no special limitations on the form of the current collector. In the art, materials such as titanium plates, titanium meshes, graphite carbon plates, graphite paper, and conductive carbon cloth are commonly used for support and current collection in capacitor deionization.

[0040] The reactions involved in the operation of the lignin-activated carbon capacitor deionization anode electrode material are as follows:

[0041] ;

[0042] .

[0043] Based on the above technical solutions, the inventive concept and principle of this invention lies in preparing anode materials by combining lignin, a biomass material, with a Bi / BiOCl system or an Ag / AgCl system that captures chloride ions through a redox reaction. This significantly reduces raw material costs, enhances the high-value-added application of lignin, and solves the problem of solid waste treatment in industries such as papermaking. The Bi or Ag precursor materials of this invention are solvent-soluble and ionized salts that bind to lignin through the positive and negative charges of their ions. This eliminates the need for prior synthesis of Ag / AgCl or Bi / BiOCl, and compared to other preparation methods, it achieves both effective and robust loading while preventing material aggregation. This method prepares the desired Bi@lignin composite materials, Ag@lignin composite materials, and AgCl@lignin composite materials through solvent exchange. Lignin molecules possess numerous negatively charged functional groups such as alcoholic and phenolic hydroxyl groups on their surface. During solvent exchange from solvent to water, molecular self-assembly results in lignin cluster nanoparticles exhibiting a large number of hydrophilic and negatively charged functional groups on their surface. This allows for material design and construction, enhancing their value-added utilization. BiOCl cannot be prepared at room temperature through solvent exchange; therefore, a hydrothermal reaction is required to prepare BiOCl@lignin composite materials. Hydrothermal reactions typically refer to chemical reactions conducted under high temperature and pressure conditions using water or other liquid media. In this process, water can be in a supercritical state, where its physical and chemical properties undergo significant changes, enabling some chemical reactions that are difficult to carry out under conventional conditions. While water is a commonly used reaction medium, it is not the only option; other liquids such as organic solvents can also serve as reaction media, provided they can achieve similar effects under specific temperature and pressure conditions.

[0044] After the desired composite material is prepared, it is calcined under an inert atmosphere. In the preparation of Bi@lignin composite materials and Ag@lignin composite materials, metal ions can be effectively reduced under high temperature, allowing Bi or Ag from the precursor to exist in elemental form, reducing the need for other reducing agents. In this invention, BiOCl@lignin composite materials are prepared by hydrothermal reaction. Bi precursor, chloride ions, and lignin react at high temperature through a redox reaction to generate BiOCl@lignin composite materials. The presence of lignin limits the large particle growth of BiOCl particles and the aggregation of nanoparticles, improving the utilization rate of BiOCl and the electrochemical cycle life. The high-temperature calcination treatment increases the conductivity of the composite material. At the same time, the gases generated during calcination are discharged from the activated carbon formed by carbonization, creating pores and increasing the specific surface area of ​​the material, which is beneficial for the transport and storage of ions in the deionization process. The anode material prepared by the method of this invention has uniformly dispersed active material, stable composite material structure, and is easy to use. Furthermore, by fixing the precursor material to the lignin framework in advance, the volume expansion of the material can be better limited, reducing the decay of desalination capacity. It exhibits excellent desalination performance when used as an electrode in technologies such as hybrid capacitor deionization, dual-ion electrochemical deionization, and membrane capacitor deionization.

[0045] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0046] This invention provides a method for preparing lignin activated carbon capacitor deionization anode electrode material, which has the advantages of convenient process, low raw material cost and wide availability, and environmental friendliness.

[0047] This invention provides a lignin activated carbon capacitor deionization anode electrode material, which has the characteristics of good stability, long service life and high adsorption capacity.

[0048] This invention provides an application of lignin activated carbon capacitor deionization anode electrode material, which has good prospects in the field of capacitor deionization and desalination. Attached Figure Description

[0049] Figure 1 The X-ray diffraction (XRD) patterns of the Bi@lignin activated carbon anode material and lignin prepared in Example 1 are shown.

[0050] Figure 2 The curve obtained by cyclic voltammetry (CV) testing of the anode prepared in Example 1 is shown.

[0051] Figure 3 The constant current charge-discharge curve of the anode prepared in Example 1;

[0052] Figure 4 The curve obtained by voltammetric cycling method for the control anode prepared in Example 2;

[0053] Figure 5 This is a schematic diagram of a capacitor deionization device.

[0054] Figure 6 (a) Conductivity curves of the capacitive deionization (CDI) device assembled with the anode of Example 1 after multiple desalinations. Figure 6 (b) is its corresponding desalination capacity diagram. Detailed Implementation

[0055] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0056] In the following embodiments:

[0057] X-ray diffractometer model: XRD-6100;

[0058] Electrochemical workstation model: Shanghai Chenhua CHI760E;

[0059] Dialysis bag model: 1K MD44.

[0060] Example 1

[0061] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0062] (1) Preparation of Bi@lignin composite material:

[0063] Weigh 0.5 g of ground alkali lignin and 0.5 g of bismuth nitrate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and bismuth nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Bi@lignin composite material;

[0064] (2) Carbonization of Bi@lignin composite materials:

[0065] Bi@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0066] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0067] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0068] The prepared Bi@lignin activated carbon anode material was characterized and analyzed using X-ray diffraction, and its XRD pattern is shown below. Figure 1 As shown. Figure 1 By comparing with standard cards of lignin and Bi, it can be seen that Bi@lignin activated carbon anode material shows obvious Bi diffraction peaks, indicating that Bi was successfully loaded in lignin and exists in the form of elemental Bi after high-temperature reduction.

[0069] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0070] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0071] Example 2

[0072] This embodiment utilizes an electrochemical workstation to study the electrochemical performance of lignin-activated carbon capacitor deionization anode electrode material at room temperature. Example 1 is used as a representative example for testing, with lignin-activated carbon as the control sample. Its preparation method is basically the same as in Example 1, except that bismuth nitrate was not added, and the control anode was prepared using the same method. In the test, the Ag / AgCl electrode was used as the reference electrode, the platinum sheet electrode as the counter electrode, and the anode of Example 1 was used as the working electrode. A 1 M sodium chloride aqueous solution was used as the electrolyte. The CV test curves of the anode of Example 1 at scan rates of 1 mV / s and 5 mV / s are shown below. Figure 2 As shown. By Figure 2 It can be seen that a pair of Bi / BiOCl redox peaks appeared near -0.75 V and -0.001 V, which is similar to the rectangular CV curve of lignin activated carbon. Figure 4The significant differences indicate that the successful loading of Bi in the composite material enhances its electrochemical performance, and the Bi@lignin activated carbon anode material exhibits superior electrochemical performance compared to lignin activated carbon. Furthermore, this invention achieved a specific capacitance as high as 207.6 F / g at a scan rate of 1 mV / s, and still maintained a specific capacitance of 168.0 F / g at a scan rate of 5 mV / s, demonstrating the excellent rate capability of the composite material. The loading of Bi facilitates the capture and storage of chloride ions, increasing the capacitor's deionization and desalination performance. The galvanostatic charge-discharge curve of the anode in Example 1 at a current density of 100 mA / g is shown below. Figure 3 As shown. By Figure 3 It can be seen that the capacitance remains stable after multiple constant current charge and discharge cycles, indicating that it has good electrochemical performance.

[0073] Example 3

[0074] This embodiment studies the application effect of lignin activated carbon capacitive deionization anode electrode material in capacitive deionization and desalination. Assembled into... Figure 5 The aforementioned capacitive deionization device specifically includes a capacitive deionization working unit, a peristaltic pump, a circulation pipeline, and a detection system. The sample brine is delivered into the capacitive deionization working unit via the peristaltic pump. A working voltage is applied within the working unit, and ions in the sample brine are captured by electrodes and flow out from the outlet, resulting in a desalinated aqueous solution. The capacitive deionization working unit is assembled from the following materials in sequence: a support plate, a gasket, a current collector, electrode material, a gasket, an anion exchange membrane, a water flow cavity, a cation exchange membrane, a gasket, an electrode material, a current collector, a gasket, and a support plate. Using the anode prepared in Example 1 as the electrode anode, and an activated carbon electrode as the electrode cathode, an anion exchange membrane was added to one side of the anode and a cation exchange membrane was added to the other side of the cathode. A 10 mM sodium chloride aqueous solution was delivered to the capacitive deionization device using a peristaltic pump, with the solution entering from the bottom and exiting from the top to ensure that there were no air bubbles in the device. The electrode clamps of the electrochemical workstation were used to clamp the corresponding electrode plates in the capacitive deionization device. The optimal speed of the peristaltic pump and the desalination time were detected using a conductivity meter, and the desalination performance was tested at different voltages. The cyclic desalination performance was tested at the optimal voltage.

[0075] Figure 6 (a) is a graph showing the change in conductivity over time after 16 tests, and its corresponding... Figure 6(b) shows the desalination capacity graph, which indicates that the desalination capacity remained essentially unchanged after 16 desalination cycles. There were even a few instances of increased desalination capacity during this period. For many current electrode materials based on the Bi / BiOCl redox couple for chlorine storage, the capacity loss due to volume expansion is severe, especially in the initial cycles, where the capacity loss can reach approximately 50%. However, the test results of this embodiment show a significant improvement in the desalination capacity decay problem. This is mainly due to the unique materials and preparation methods used in this invention, which effectively optimize the shortcomings of existing technologies.

[0076] Example 4

[0077] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0078] (1) Preparation of Bi@lignin composite material:

[0079] Weigh 0.5 g of ground lignin and 0.5 g of bismuth nitrate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and bismuth nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Bi@lignin composite material;

[0080] (2) Carbonization of Bi@lignin composite materials:

[0081] Bi@lignin composite material was placed in a tube furnace and carbonized at 600 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0082] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0083] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0084] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0085] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0086] Example 5

[0087] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0088] (1) Preparation of Bi@lignin composite material:

[0089] Weigh 2 g of ground lignin and 0.5 g of bismuth nitrate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and bismuth nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Bi@lignin composite material;

[0090] (2) Carbonization of Bi@lignin composite materials:

[0091] Bi@lignin composite material was placed in a tube furnace and carbonized at 900 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0092] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0093] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0094] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0095] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0096] Example 6

[0097] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0098] (1) Preparation of Bi@lignin composite material:

[0099] Weigh 0.5 g of high-boiling-point lignin and 0.5 g of bismuth nitrate into a beaker, add an appropriate amount of tetrahydrofuran, and prepare a 50 mL solution. Stir the solution on a magnetic stirrer until the high-boiling-point lignin and bismuth nitrate are completely dissolved to obtain a mixture. Cut a dialysis bag of appropriate length, fill it with the mixture, and dialyze it in deionized water for 24 h. After dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 °C to obtain Bi@lignin composite material.

[0100] (2) Carbonization of Bi@lignin composite materials:

[0101] Bi@lignin composite material was placed in a tube furnace and carbonized at 900 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0102] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0103] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0104] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0105] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0106] Example 7

[0107] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0108] (1) Preparation of Bi@lignin composite material:

[0109] Weigh 0.5 g of enzymatically hydrolyzed lignin and 0.5 g of bismuth nitrate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the enzymatically hydrolyzed lignin and bismuth nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Bi@lignin composite material;

[0110] (2) Carbonization of Bi@lignin composite materials:

[0111] Bi@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0112] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0113] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0114] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0115] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0116] Example 8

[0117] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0118] (1) Preparation of Bi@lignin composite material:

[0119] Weigh 0.5 g of ground lignin and 0.5 g of bismuth acetate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and bismuth acetate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Bi@lignin composite material;

[0120] (2) Carbonization of Bi@lignin composite materials:

[0121] Bi@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0122] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0123] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0124] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0125] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0126] Example 9

[0127] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0128] (1) Preparation of Bi@lignin composite material:

[0129] Weigh 0.5 g of ground lignin and 0.5 g of bismuth phosphate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and bismuth phosphate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Bi@lignin composite material;

[0130] (2) Carbonization of Bi@lignin composite materials:

[0131] Bi@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0132] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0133] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0134] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0135] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0136] Example 10

[0137] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0138] (1) Preparation of Ag@lignin composite material:

[0139] Weigh 0.5 g of ground lignin and 0.5 g of silver nitrate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and silver nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Ag@lignin composite material;

[0140] (2) Carbonization of Ag@lignin composite materials:

[0141] Ag@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Ag@lignin activated carbon anode material.

[0142] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0143] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Ag@lignin activated carbon anode material.

[0144] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0145] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0146] Example 11

[0147] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0148] (1) Preparation of Ag@lignin composite material:

[0149] Weigh 0.5 g of ground lignin and 0.5 g of silver trifluoroacetate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and silver trifluoroacetate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Ag@lignin composite material;

[0150] (2) Carbonization of Ag@lignin composite materials:

[0151] Ag@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Ag@lignin activated carbon anode material.

[0152] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0153] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Ag@lignin activated carbon anode material.

[0154] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0155] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0156] Example 12

[0157] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0158] (1) Preparation of Bi@lignin composite material:

[0159] Weigh 0.5 g of ground lignin and 0.5 g of bismuth nitrate into a beaker, add an appropriate amount of acetone to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and bismuth nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Bi@lignin composite material;

[0160] (2) Carbonization of Bi@lignin composite materials:

[0161] Bi@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Bi@lignin activated carbon anode material.

[0162] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0163] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Bi@lignin activated carbon anode material.

[0164] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0165] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0166] Example 13

[0167] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0168] (1) Preparation of Ag@lignin composite material:

[0169] Weigh 0.5 g of ground lignin and 0.5 g of silver nitrate into a beaker, add an appropriate amount of ethanol to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and silver nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in deionized water for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 ℃ to obtain Ag@lignin composite material;

[0170] (2) Carbonization of Ag@lignin composite materials:

[0171] Ag@lignin composite material was placed in a tube furnace and carbonized at 800 °C for 2 h under an inert atmosphere to obtain Ag@lignin activated carbon anode material.

[0172] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0173] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is Ag@lignin activated carbon anode material.

[0174] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0175] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0176] Example 14

[0177] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0178] (1) Preparation of BiOCl@lignin composite material:

[0179] 0.5 g of bismuth nitrate pentahydrate and 0.09 g of potassium chloride were dissolved in 10 mL of ethylene glycol. 0.1 g of lignin and 50 mL of ethanol were added to the above mixed solution. After stirring and dissolving, the mixture was transferred to a hydrothermal reactor and reacted at 160 °C for 24 h. The prepared solid particles were collected, filtered, washed with distilled water, and dried at 60 °C to obtain BiOCl@lignin composite material.

[0180] (2) Carbonization of BiOCl@lignin composite materials:

[0181] BiOCl@lignin composite material was placed in a tube furnace and carbonized at 500 °C for 2 h under an inert atmosphere to obtain BiOCl@lignin activated carbon anode material.

[0182] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0183] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is BiOCl@lignin activated carbon anode material.

[0184] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0185] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0186] Example 15

[0187] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0188] (1) Preparation of BiOCl@lignin composite material:

[0189] 1.5 g of bismuth nitrate pentahydrate and 0.25 g of potassium chloride were dissolved in 10 mL of ethylene glycol. 0.2 g of lignin and 50 mL of ethanol were added to the above mixed solution. After stirring and dissolving, the mixture was transferred to a hydrothermal reactor and reacted at 160 °C for 24 h. The prepared solid particles were collected, filtered, washed with distilled water, and dried at 60 °C to obtain BiOCl@lignin composite material.

[0190] (2) Carbonization of BiOCl@lignin composite materials:

[0191] BiOCl@lignin composite material was placed in a tube furnace and carbonized at 500 °C for 2 h under an inert atmosphere to obtain BiOCl@lignin activated carbon anode material.

[0192] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0193] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is BiOCl@lignin activated carbon anode material.

[0194] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0195] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0196] Example 16

[0197] The preparation method of lignin activated carbon capacitor deionization anode electrode material includes the following steps:

[0198] (1) Preparation of AgCl@lignin composite material:

[0199] Weigh 0.5 g of ground lignin and 0.5 g of silver nitrate into a beaker, add an appropriate amount of tetrahydrofuran to prepare a 50 mL solution, stir on a magnetic stirrer until the lignin and silver nitrate are completely dissolved to obtain a mixture; cut an appropriate length of dialysis bag, put the above mixture into it, and dialyze in an aqueous solution containing 10 mmol sodium chloride for 24 h; after dialysis, centrifuge at 3000 rpm, wash with deionized water, and dry at 50 °C to obtain AgCl@lignin composite material;

[0200] (2) Carbonization of AgCl@lignin composite materials:

[0201] AgCl@lignin composite material was placed in a tube furnace and carbonized at 400 °C for 2 h under an inert atmosphere to obtain AgCl@lignin activated carbon anode material.

[0202] (3) Obtaining lignin-activated carbon capacitor deionization anode electrode material:

[0203] In this embodiment, the lignin activated carbon capacitor deionization anode electrode material is AgCl@lignin activated carbon anode material.

[0204] This embodiment also provides an anode made of lignin activated carbon capacitor deionization anode electrode material, the steps of which are as follows:

[0205] The lignin activated carbon capacitor deionization anode electrode material, conductive carbon powder and PVDF were mixed in an agate crucible in a ratio of 8:1:1. NMP was added dropwise and ground evenly. After grinding evenly, the mixture was spread on graphite paper that had been weighed and recorded. The mixture was then placed in a blower dryer to dry. After drying, the mixture was weighed and recorded to obtain the prepared anode.

[0206] In summary, this invention utilizes lignin, a renewable biomass material containing abundant phenolic and alcoholic hydroxyl groups, which is environmentally friendly, low-cost, and easy to use. A simple and highly operable preparation method is used to form lignin microspheres. These microspheres increase the specific surface area of ​​the material, and their surface is covered with numerous negatively charged groups that can interact with metal ions. This allows for the loading of Ag and Bi, which electrochemically capture chloride ions, into the microspheres, effectively suppressing the large volume expansion caused by Ag and Bi during the electrochemical capture of chloride ions and enhancing their adsorption capacity as an anode. Unlike other MOF-derived carbons, this invention selects lignin as a suitable carbon material for practical production applications. Compared to other materials, such as aerogels and flexible membranes composed of two-dimensional nanomaterials, lignin exhibits greater mechanical strength, better stability, and a relatively longer service life. As a biomacromolecule, lignin firmly locks in metal elements through charge interactions and can self-assemble through hydrogen or π-bond interactions, making the entire composite material structure more robust and effective. This results in an anode electrode material with greater capacity and a faster adsorption rate, effectively avoiding adsorption capacity loss due to volume expansion and increasing the electrode's service life. The lignin activated carbon capacitive deionization anode electrode material prepared by this invention has a wide range of applications. It is well-suited for traditional capacitive deionization devices based on electrochemical ion capture, such as capacitive deionization, membrane capacitive deionization, and dual-ion electrochemical deionization, and has broad application prospects.

[0207] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a lignin activated carbon capacitive deionization anode electrode material, characterized in that, The method comprises the following steps: (1) According to the components of the lignin activated carbon capacitive deionization anode electrode material, the corresponding composite material is prepared: a. Mix lignin, Bi precursor or Ag precursor with a solvent, and complete solvent exchange by dialysis in water to obtain the corresponding Bi@lignin composite material or Ag@lignin composite material; b. Mix lignin, Ag precursor and solvent, and complete solvent exchange by dialysis in an aqueous solution of a chloride salt to obtain AgCl@lignin composite material; c. Mix lignin, Bi precursor and chloride salt with a solvent, and then perform hydrothermal reaction; after the hydrothermal reaction, BiOCl@lignin composite material is recovered; The Bi precursor, Ag precursor and chloride salt are salts dissolved in the solvent and ionized; In the step (1), the solvent includes at least one of tetrahydrofuran, ethanol, ethylene glycol, acetone, dimethyl sulfoxide and dichloromethane; (2) Carbonization of the composite material: The Bi@lignin composite material, Ag@lignin composite material, AgCl@lignin composite material and BiOCl@lignin composite material are subjected to calcination treatment under an inert atmosphere to complete carbonization, and the corresponding Bi@lignin activated carbon anode material, BiOCl@lignin activated carbon anode material, Ag@lignin activated carbon anode material and AgCl@lignin activated carbon anode material are obtained; (3) Obtain lignin activated carbon capacitive deionization anode electrode material: The lignin activated carbon capacitive deionization anode electrode material includes at least one of Bi@lignin activated carbon anode material, BiOCl@lignin activated carbon anode material, Ag@lignin activated carbon anode material and AgCl@lignin activated carbon anode material.

2. The method of claim 1, wherein the lignin activated carbon electrode material for capacitive deionization is prepared by the steps of: a) mixing lignin and activated carbon to form a mixture; b) adding a binder to the mixture; c) mixing the binder and the mixture; d) forming the mixture into a desired shape; and e) drying the mixture. In the step (1), the lignin includes at least one of alkali lignin, eucalyptus lignin, high-boiling alcohol lignin, organic solvent lignin, kraft lignin and enzymatic hydrolysis lignin; the Bi precursor includes bismuth salt and its hydrate, and the bismuth salt includes at least one of bismuth nitrate, bismuth chloride, bismuth sulfate, bismuth acetate, bismuth citrate, bismuth iodide, bismuth bromide and bismuth phosphate; the Ag precursor includes silver salt and its hydrate, and the silver salt includes at least one of silver nitrate, silver acetate and silver trifluoroacetate; the mass ratio of the Bi precursor or Ag precursor to lignin is 0.2-2:

1.

3. The method of claim 1, wherein the lignin activated carbon electrode material for capacitive deionization is prepared by the steps of: a) mixing lignin and activated carbon to form a mixture; b) adding a binder to the mixture; c) mixing the binder and the mixture; d) forming the mixture into a desired shape; and e) drying the mixture. In the step (1), the chloride salt includes at least one of sodium chloride and potassium chloride; the concentration of the aqueous solution of the chloride salt is 1-20 mM; the ratio of Bi atoms or Ag atoms in the Bi precursor or Ag precursor to chlorine atoms in the chloride salt is 1-20:

1.

4. The method of claim 1, wherein the lignin activated carbon electrode material for capacitive deionization is prepared by the steps of: a) mixing lignin and activated carbon to form a mixture; b) adding a binder to the mixture; c) mixing the binder and the mixture; d) forming the mixture into a desired shape; and e) drying the mixture. In the step (1), the molecular weight of the dialysis is 1-12 KD.

5. The method of claim 1, wherein the lignin activated carbon electrode material for electro-deionization is prepared by the steps of: a) mixing lignin and activated carbon to form a mixture; b) adding a binder to the mixture; c) mixing the binder and the mixture; d) forming the mixture into a desired shape; and e) drying the mixture. In the step (1), the temperature of the hydrothermal reaction is 160 ℃, and the reaction time is 24 h.

6. The method of claim 1, wherein the lignin activated carbon electrode material for capacitive deionization is prepared by the steps of: a) mixing lignin and activated carbon to form a mixture; b) adding a binder to the mixture; c) mixing the binder and the mixture; d) forming the mixture into a desired shape; and e) drying the mixture. In the step (2), the temperature of the calcination treatment is 400-1000 ℃, and the calcination time is 0.5-3 h.

7. A lignin activated carbon capacitive deionization anode electrode material, characterized in that: The preparation method is prepared by using any one of the preparation methods in claims 1-6.

8. Use of the lignin activated carbon electrode material for capacitive deionization anode as claimed in claim 7, wherein: The application of the preparation method as the anode material in capacitive deionization desalination.

9. The use of a lignin activated carbon capacitive deionization anode electrode material according to claim 8, characterized in that, The method of application comprises the following steps: mixing lignin activated carbon capacitive deionization anode electrode material with conductive agent, binder and solvent to prepare anode slurry, then coating the anode slurry on the surface of a current collector and drying to form an anode; assembling a capacitive deionization desalination device including the anode, which is used for capacitive deionization desalination.

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