Three-dimensional photocatalytic sponge block with controllable size and shape as well as preparation method and application of three-dimensional photocatalytic sponge block

Abstract

The invention relates to the technical field of photocatalysis, in particular to a size and shape controllable three-dimensional photocatalytic sponge block and a preparation method and application thereof. The preparation method comprises the following steps: converting graphite powder in the waste lithium battery into graphene oxide by using an improved hummer's method, mixing the graphene oxide with NaOH and chloroacetic acid, and carrying out ultrasonic treatment to obtain carboxylated graphene oxide; and dissolving the carboxylated graphene oxide in water, mixing with a chitosan solution, and stirring to obtain the three-dimensional photocatalytic sponge block. The carboxylated graphene oxide has extremely sensitive selective adsorbability, the purpose of photochemical adsorption is achieved by utilizing the overall mild photocatalytic performance of the carboxylated graphene oxide, various rare earth elements are effectively and selectively recovered, and meanwhile, chitosan is adopted as a three-dimensional framework of the carboxylated graphene oxide, so that the adsorption capacity of the carboxylated graphene oxide is further improved; and a functional photocatalytic material which is controllable in shape and size is prepared.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, and in particular to a three-dimensional photocatalytic sponge block with controllable size and shape, its preparation method, and its application. Background Technology

[0002] Current lithium battery recycling technology focuses heavily on the extraction of high-value metals (cobalt, nickel, and lithium), with cathode material recovery rates exceeding 95%. However, graphite anodes, which account for 15-25% of battery mass, are systematically neglected and often treated as hazardous waste for incineration. This value blind spot stems from two major misjudgments: first, underestimating the performance of recycled graphite; and second, ignoring its high-value potential—expanded graphite can be transformed into sodium-ion battery anodes, graphene precursors, or environmentally friendly adsorbents.

[0003] The recycling of waste graphite possesses a unique and forward-looking perspective, particularly in the area of ​​functional group modification. Utilizing the specific effects of different functional groups allows for reuse in various fields. Graphene oxide contains a variety of functional groups, and the interconversion relationships between these functional groups are a core aspect of its high-value utilization. Currently, functionalization methods such as amination, hydroxylation, and grapheneization are particularly innovative and can be applied in battery manufacturing, adsorption, and wastewater metal removal processes. However, the excellent mildness and selective recycling properties of carboxylation have not been fully developed; therefore, the preparation methods and applications of this material should be given due attention. While rare earth elements currently occupy the largest share of my country's mineral resources, these resources require special protection due to their crucial importance in many fields, especially high-tech areas. Currently, there are no effective technologies or application materials for rare earth recycling. Furthermore, due to the relatively low abundance of rare earth elements, adsorption from water and soil using adsorbents is easily interfered with by other high-abundance elements, resulting in high adsorption impurities and failing to achieve the desired recycling outcome.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a three-dimensional photocatalytic sponge block with controllable size and shape, its preparation method and application, in order to solve the problem of high adsorption impurities in the existing method of recovering rare earth elements using adsorbents.

[0006] The technical solution of the present invention is as follows: A method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, comprising the following steps: A modified Hummer's method was used to convert graphite powder in waste lithium batteries into graphene oxide. The graphene oxide was mixed with NaOH and chloroacetic acid, and then subjected to ultrasonic treatment to obtain carboxylated graphene oxide. Chitosan was mixed with glacial acetic acid to obtain a chitosan solution; The carboxylated graphene oxide was dissolved in water and then mixed with the chitosan solution. After stirring, a three-dimensional photocatalytic sponge block was obtained.

[0007] The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, wherein the step of converting graphite powder from waste lithium batteries into graphene oxide using a modified Hummel's method includes: The graphite powder from the waste lithium battery was mixed with sodium nitrate and sulfuric acid in an ice-water bath to obtain the first mixed solution. The first mixed solution is mixed with potassium permanganate, stirred, and then heated to 35℃-40℃ and maintained for 1h-2h to obtain the second mixed solution. Deionized water was added to the second mixed solution, the temperature was raised to 85℃-95℃ and the reaction was maintained for 1h-2h, and then H2O2 was added to obtain graphene oxide.

[0008] The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, wherein the mass ratio of graphite powder to sodium nitrate is (2-3):1.

[0009] The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, wherein the mass ratio of graphene oxide to NaOH and chloroacetic acid is 1:(25-35):(20-30).

[0010] The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, wherein the concentration of the chitosan solution is 4 mg / mL-7 mg / mL.

[0011] The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, wherein the stirring process is performed by stirring with an oscillator at a speed of 500 rpm to 700 rpm for 10 min to 20 min.

[0012] A three-dimensional photocatalytic sponge block with controllable size and shape is prepared by the method for preparing the three-dimensional photocatalytic sponge block with controllable size and shape.

[0013] Application of a three-dimensional photocatalytic sponge block with controllable size and shape in a rare earth element photocatalytic recovery device.

[0014] The application described herein includes a rare earth element photocatalytic recovery device comprising: a plurality of reaction chambers with cylindrical slots, an excitation light source disposed within the cylindrical slots, a reaction pipe for connecting the plurality of reaction chambers in series, and a power pump disposed on a section of the reaction pipe; a three-dimensional photocatalytic sponge block matching the shape of the cylindrical slot is disposed within the cylindrical slot.

[0015] In the aforementioned application, the rare earth element includes one or more of Pr, Fe, Ce, and Gd.

[0016] Beneficial effects: This invention provides a three-dimensional photocatalytic sponge block with controllable size and shape, its preparation method, and its application. The preparation method includes the following steps: converting graphite powder from waste lithium batteries into graphene oxide using a modified Hummer's method; mixing the graphene oxide with NaOH and chloroacetic acid, followed by ultrasonic treatment to obtain carboxylated graphene oxide; mixing chitosan with glacial acetic acid to obtain a chitosan solution; dissolving the carboxylated graphene oxide in water and mixing it with the chitosan solution, followed by stirring to obtain the three-dimensional photocatalytic sponge block. The carboxylated graphene oxide (GO-COOH) of this invention exhibits extremely sensitive selective adsorption. Utilizing its overall mild photocatalytic performance, it achieves photochemical adsorption, effectively and selectively recovering various rare earth elements. Furthermore, this invention employs chitosan (CS) as the three-dimensional framework of the carboxylated graphene oxide, further enhancing its adsorption capacity. Moreover, it prepares a functional photocatalytic material with controllable shape and size, applicable to self-made continuous flow photocatalytic devices for continuous photocatalytic recovery. Furthermore, three-dimensional photocatalytic sponges of different sizes and shapes can be prepared according to the functional shapes of different devices, greatly enhancing and broadening the application depth and scope of three-dimensional photocatalytic sponges. In addition, this method improves the high-value utilization of graphite anodes in waste lithium batteries. By constructing a "recycling-regeneration-application" closed loop, it not only achieves full component resource utilization but also unlocks its enormous application potential in high-end materials and green recycling. Simultaneously, the three-dimensional photocatalytic sponge blocks rely on light energy to achieve green recovery of rare earth elements. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process flow for a method of preparing a three-dimensional photocatalytic sponge block with controllable size and shape according to the present invention; Figure 2 This is a schematic diagram of a rare earth element photocatalytic recovery device. Figure 3 The theoretical model and physical diagram of GO-COOH / CS synthesized from GO-COOH and CS in Example 1 are shown. Figure 4The images show the morphology and structure of the GO-COOH / CS sponge prepared in Example 1. Figure 5 SEM and EDS images of the GO-COOH / CS sponge prepared in Example 1; Figure 6 The graph shows the adsorption efficiency test results of rare earth elements on the GO-COOH / CS sponge prepared in Example 1. Figure 7 The XRD patterns of the GO-COOH / CS sponge prepared in Example 1 after adsorption under different environments are shown. Detailed Implementation

[0018] This invention provides a three-dimensional photocatalytic sponge block with controllable size and shape, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0020] like Figure 1 As shown, this invention provides a method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, comprising the following steps: Step S10: Convert graphite powder in waste lithium batteries into graphene oxide using the modified Hummer's method. Step S20: The graphene oxide is mixed with NaOH and chloroacetic acid, and then subjected to ultrasonic treatment to obtain carboxylated graphene oxide; Step S30: Mix chitosan with glacial acetic acid to obtain a chitosan solution; Step S40: Dissolve the carboxylated graphene oxide in water and mix it with the chitosan solution. After stirring, a three-dimensional photocatalytic sponge block is obtained.

[0021] In this embodiment, carboxylated graphene oxide (GO-COOH) exhibits extremely sensitive selective adsorption. Utilizing its overall mild photocatalytic performance, it achieves photochemical adsorption, effectively and selectively recovering various rare earth elements. Furthermore, this invention employs chitosan (CS) as the three-dimensional framework of the carboxylated graphene oxide, further enhancing its adsorption capacity. Moreover, it prepares a functional photocatalytic material with controllable shape and size, applicable to self-made continuous flow photocatalytic devices, achieving continuous photocatalytic recovery. Furthermore, three-dimensional photocatalytic sponges of different sizes and shapes are prepared according to the functional shapes of different devices, greatly enhancing and broadening the application depth and scope of the three-dimensional photocatalytic sponges. In addition, this method improves the high-value utilization of graphite anodes in waste lithium batteries. By constructing a "recycling-regeneration-application" closed loop, it not only achieves full component resource utilization but also unlocks its enormous application potential in high-end materials and green recycling. Simultaneously, the three-dimensional photocatalytic sponges rely on light energy to achieve green recovery of rare earth elements.

[0022] Specifically, this invention employs a modified Hummer's method to convert low-value graphite from waste lithium batteries into graphene oxide, followed by the conversion of this graphene oxide into carboxylated graphene oxide using chloroacetic acid. This material exhibits excellent photocatalytic reduction capabilities, reducing rare earth metal ions in wastewater to rare earth metal atoms, and subsequently collecting rare earth metal powder. Simultaneously, to enhance performance, chitosan is used as a framework binder to create a customizable three-dimensional porous foam structure, significantly improving its photocatalytic performance for rare earth metal ions and realizing a method for transforming low-value materials into high-value ones. Furthermore, the preparation method of this invention enhances the ion adsorption and catalytic properties of GO-COOH and CS, thereby improving ion extraction rate, faster adsorption rate, and increased selectivity for rare earth ions. This three-dimensional photocatalytic sponge block also possesses various shape flexibility, serving as an important photocatalyst for photocatalytic adsorption.

[0023] Furthermore, the presence of oppositely charged functional groups and water-transporting domains in carboxylated graphene oxide and chitosan ensures interfacial compatibility and stability. These multiple interactions between two-dimensional materials and one-dimensional macromolecules produce a synergistic effect, enhancing the performance of the combined system beyond that of its individual components. Simultaneously, this invention utilizes a self-assembly method to synthesize three-dimensional photocatalytic sponge blocks. This method enables GO-COOH and CS to self-organize into GO-COOH / CS building blocks and assemble them into well-defined nanolayers with chemically active nano-constraints. This approach draws inspiration from biological and physical systems where organization spontaneously emerges from functional components or building blocks.

[0024] In some embodiments, step S10, the step of converting graphite powder in spent lithium batteries into graphene oxide using a modified Hummer's method, includes: Step S11: Mix the graphite powder from the waste lithium battery with sodium nitrate and sulfuric acid in an ice-water bath to obtain the first mixed solution; Step S12: Mix the first mixed solution with potassium permanganate, stir, heat to 35℃-40℃ and maintain for 1h-2h to obtain the second mixed solution; Step S13: Add deionized water to the second mixed solution, heat to 85℃-95℃ and maintain the reaction for 1h-2h, then add H2O2 to obtain graphene oxide.

[0025] In this embodiment, the improved method accelerates the preparation speed of graphene oxide by gradually increasing the temperature, and further reduces the proportion of reagents such as concentrated sulfuric acid by heating, thereby reducing environmental pollution.

[0026] In some embodiments, the mass ratio of the graphite powder to the sodium nitrate is (2-3):1.

[0027] Specifically, graphite powder and sodium nitrate were placed in a three-necked flask at a mass ratio of 2:1 with 80 ml of concentrated sulfuric acid and kept in an ice-water bath. The mixture was stirred continuously at 500 rpm for 30 minutes. Then, 9 g of potassium permanganate was added and stirred at 20 °C for 2 hours. The temperature was then raised to 35-40 °C and maintained for 1 hour. 150 ml of deionized water was added, and the temperature was raised to 90 °C and maintained for 1 hour. Then, 500 ml of deionized water was added, and the mixture was allowed to cool naturally to room temperature. After the reaction was completed, 20 ml of H2O2 was slowly added dropwise to the yellowish-brown solution, taking care to prevent bubbles from escaping.

[0028] In some embodiments, the mass ratio of the graphene oxide to the NaOH and the chloroacetic acid is 1:(25-35):(20-30).

[0029] Specifically, a mixed suspension was prepared by mixing graphene oxide suspension with NaOH and chloroacetic acid at a mass ratio of 1:30:25. The mixed suspension was then ultrasonically treated for 2 hours, centrifuged, washed with 0.1M hydrochloric acid and deionized water, and the resulting GO-COOH was dried in an oven for subsequent use.

[0030] In some embodiments, the concentration of the chitosan solution is 4 mg / mL to 7 mg / mL.

[0031] In some embodiments, step S40 specifically includes: mixing carboxylated graphene oxide with deionized water to obtain a diluted carboxylated graphene oxide dispersion with a concentration of 0.2 mg / mL; subsequently, mixing chitosan solution and carboxylated graphene oxide dispersion at a volume ratio of 1:15, and stirring with a shaker for 10 minutes; after freeze-drying, a three-dimensional sponge block can be obtained. During the freeze-drying process, different sizes and shapes of three-dimensional photocatalytic sponge blocks can be formed by using different molds.

[0032] In some embodiments, the stirring process is performed by stirring with an oscillator at a speed of 500 rpm to 700 rpm for 10 min to 20 min.

[0033] In addition, the present invention also provides a three-dimensional photocatalytic sponge block with controllable size and shape, which is prepared by the method for preparing the three-dimensional photocatalytic sponge block with controllable size and shape.

[0034] In this embodiment, carboxylated graphene oxide (GO-COOH) possesses strong adsorption and photocatalytic properties, exhibiting inherent metal ion adsorption capabilities. Chitosan (CS) also possesses adsorption capacity, and its unique functional group structure allows for the synthesis of CO-COOH / CS materials through crosslinking with GO-COOH, enhancing its adsorption performance for rare earth metal ions. GO-COOH itself exhibits a unique photocatalytic effect, enabling better adsorption and catalysis of rare earth elements in water. The primary reason for this adsorption capability lies in the covalent functional groups and excellent photocatalytic performance of graphene. Furthermore, this method allows for the preparation of three-dimensional photocatalytic sponge blocks of varying sizes and shapes to suit different devices, significantly expanding the application depth and scope of these three-dimensional photocatalytic sponge blocks.

[0035] Specifically, this invention is based on carboxyl-functionalized graphene oxide (GO-COOH) material. A multi-level porous three-dimensional network structure is constructed using microreactor confined self-assembly technology, achieving a leap in specific surface area, optimized adsorption kinetics, and enhanced selectivity. Furthermore, a microfluidic aerosol template method is employed to generate monodisperse three-dimensional functionalized graphene microspheres. A gradient pore structure (macroporous framework → mesoporous channels → microporous active sites) is constructed within the microspheres, enabling three-dimensional topological control. Simultaneously, the carboxyl group (-COOH) density in the three-dimensional framework of this three-dimensional photocatalytic sponge reaches 4.2 mmol / g. Through a chelation-in-situ photoreduction coupling mechanism and the material's inherent strong adsorption properties, it jointly undertakes the task of removing rare earth elements from water.

[0036] In addition, this invention also provides the application of a three-dimensional photocatalytic sponge block with controllable size and shape in a rare earth element photocatalytic recovery device.

[0037] In this embodiment, the functional photocatalytic material with controllable shape and size prepared by the present invention can be applied to a self-made continuous flow photocatalytic device to achieve continuous photocatalytic recovery. Furthermore, three-dimensional photocatalytic sponge blocks of different sizes and shapes can be prepared according to the functional shape of different devices, which greatly enhances and broadens the application depth and field of three-dimensional photocatalytic sponge blocks.

[0038] In some implementations, such as Figure 2 As shown, the rare earth element photocatalytic recovery device includes: a plurality of reaction chambers with cylindrical slots, an excitation light source disposed in the cylindrical slots, a reaction pipe for connecting the plurality of reaction chambers in series, and a power pump disposed on a section of the reaction pipe; a three-dimensional photocatalytic sponge block matching the shape of the cylindrical slot is disposed in the cylindrical slot.

[0039] Specifically, a three-dimensional photocatalytic sponge block, molded and shaped within the cylindrical cavity, forms an adsorption interface with a porosity ≥85% through its chitosan three-dimensional network structure. An adjustable LED excitation light source with a wavelength of 380-450nm is arranged around the cavity, with the distance between the LED and the three-dimensional photocatalytic sponge block completely covering the flow channel cross-section. Then, a power pump drives the rare earth ion-containing waste liquid through an axial serpentine flow channel (i.e., the reaction pipe) at a flow rate of 1mL / min-4mL / min, ensuring a fluid contact time ≥120 seconds. During operation, the LED excitation light source excites GO-COOH to generate photogenerated electron-hole pairs. GO-COOH selectively chelates rare earth ions, while the micro-nano pores of the CS multiply the adsorption sites, achieving directional recovery of rare earth concentration in the effluent to below 1ppm.

[0040] In some embodiments, the rare earth element includes one or more of Pr, Fe, Ce, and Gd.

[0041] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0042] Example 1 This embodiment provides a three-dimensional photocatalytic sponge block (GO-COOH / CS), and the specific preparation process is as follows: 1) Preparation of graphene oxide using a modified Hummer's method Anode graphite powder was collected from waste lithium batteries. 3g of the anode graphite powder was placed in a three-necked flask and placed in an ice-water bath. Then, 1.5g of sodium nitrate and 80ml of sulfuric acid (98% by volume) were added, and the mixture was stirred continuously at 500 rpm for 30 minutes. Next, 9g of potassium permanganate was added, and the mixture was stirred at 20°C for 2 hours. The temperature was then raised to 35-40°C and maintained for 1 hour. 150ml of deionized water was added, and the temperature was raised to 90°C and maintained for 1 hour. Then, 500mL of deionized water was added, and the mixture was allowed to cool naturally to room temperature. After the reaction was complete, 20mL of H₂O₂ was slowly added dropwise to the yellowish-brown solution to prevent bubbles from overflowing. Finally, the solution was freeze-dried to obtain graphene oxide (GO).

[0043] 2) Preparation of carboxylated graphene oxide After adding NaOH (6g) and chloroacetic acid (5g) to the graphene oxide suspension (200mg GO + 100mL deionized water), the mixed suspension was sonicated for 2 hours, centrifuged, washed with 0.1M hydrochloric acid and deionized water, and the resulting carboxylated graphene oxide (GO-COOH) was finally dried in an oven for subsequent use.

[0044] 3) Preparation of three-dimensional photocatalytic sponge blocks (GO-COOH / CS) By dissolving chitosan (2g) in glacial acetic acid (5mg / mL) -1 A chitosan / glacial acetic acid (CS / HOAc) dispersion was prepared by magnetically stirring a 50 mL solution at room temperature for 24 hours. A carboxylated graphene oxide aqueous solution (4 mg / mL) was then added. -1 Add 20 mL of GO-COOH to 380 mL of deionized water to obtain a diluted GO-COOH dispersion (0.2 mg / mL). -1 Then CS / HOAc (5 mL, 5 mg mL) was added. -1 ) dispersion and GO-COOH dispersion (25 mL, 0.2 mg mL) -1 Mix the ingredients and stir with a shaker (500 rpm, vortex mixer) for 10 minutes. Place the mixture in a 24-well culture plate and freeze-dry for 24 hours to prepare GO-COOH / CS sponge.

[0045] The theoretical model and physical diagram of GO-COOH / CS synthesis from GO-COOH and CS are shown below. Figure 3 As shown in a and b in the figure.

[0046] The control group can be prepared by freeze-drying 2 mL of GO-COOH dispersion (0.2 mg / mL). -1 ) or 0.8 mL CS / HOAc dispersion (5 mg / mL)-1 The original porous sponge block can be easily prepared in a perforated plate.

[0047] The morphology and structure of the GO-COOH / CS sponge prepared in this embodiment were characterized, such as... Figure 4 As shown, where, Figure 4 Image a shows a scanning electron microscope image of carboxyl-functionalized GO, revealing its grooved, wrinkled appearance. Image b compares the XRD patterns of GO before and after carboxyl functionalization. The XRD pattern after carboxylation shows increased structural graphitization, which enhances the electronic conductivity of the material. Image c compares the Raman spectra of GO before and after carboxyl functionalization. Similarly, the shift and ratio of the D and G bands recorded in the Raman spectra confirm the increased graphitization degree after carboxylation. Image d compares the XPS spectra of GO before and after carboxyl functionalization. The difference in C and O content in the carboxylated material can be demonstrated by the XPS spectra, especially the increase in oxygen content after carboxylation. Images e and f show the TEM and EDS imaging characterization results of GO-COOH, respectively, which also verify the regional distribution of elements in carboxylated GO. Based on these characterization results, it is concluded that GO-COOH was successfully synthesized, and its degree of graphitization is beneficial for subsequent application development and use. SEM and EDS images of GO-COOH / CS sponge are shown below. Figure 5 As shown, it can be seen that after being three-dimensionalized, it exhibits a porous structure with a higher specific surface area.

[0048] The adsorption efficiency of rare earth elements by the GO-COOH / CS sponge prepared in this embodiment was tested, and the results are as follows: Figure 6 As shown, where, Figure 6 In the figures, 'a' represents the comparison of adsorption efficiency under light / dark conditions, and the comparison of adsorption capacity under light; 'b' represents the adsorption capacity of Pr, Fe, and Ce; 'c' represents the adsorption efficiency at a representative pH; and 'd' represents the efficiency at adsorption equilibrium at different times. It can be seen that the GO-COOH / CS sponge demonstrates both photocatalytic recovery performance and efficiency for various key rare earth elements, achieving performance breakthroughs under specific application environments and adsorption conditions. GO-COOH / CS itself possesses unique self-adsorption capacity, and under light conditions, due to the good conductivity and ion transport efficiency of the two materials in GO-COOH / CS, photocatalysis also contributes a significant portion of the efficiency, especially for the adsorption efficiency of Pr, Fe, Ce, and Gd. Figure 6 (a) exhibits extremely high adsorption capacity and retains extremely high adsorption saturation capacity at different initial concentrations. Figure 6 (b) in the middle. Figure 6In the c-component, GO-COOH / CS still exhibits significant recovery capabilities for Pr, Fe, Ce, and Gd, with the highest recovery efficiency at pH 6. For these rare earth elements, the high recovery efficiency of the functional material is demonstrated within one hour, such as... Figure 6 As shown in d, adsorption equilibrium was reached after 1 hour of adsorption under light.

[0049] XRD patterns after adsorption under different environments are as follows Figure 7 As shown, the main peaks of the XRD clearly show a rightward shift, indicating that the interlayer spacing of the material structure has widened accordingly. The main peak shift is the largest under light conditions, indicating that rare earth elements in the water are adsorbed into the interlayer of the material after adsorption. The shift is smaller under dark conditions, indicating that the material's highest performance is not fully realized under dark conditions and adsorption equilibrium is reached prematurely. Therefore, GO-COOH has a part of the light-driven reaction during the adsorption process, and its adsorption performance can be further enhanced under light.

[0050] The adsorption content of rare earth elements by GO-COOH / CS is shown in Table 1: Table 1

[0051] In summary, this invention provides a three-dimensional photocatalytic sponge block with controllable size and shape, its preparation method, and its application. The preparation method includes the following steps: converting graphite powder from waste lithium batteries into graphene oxide using a modified Hummer's method; mixing the graphene oxide with NaOH and chloroacetic acid, followed by ultrasonic treatment to obtain carboxylated graphene oxide; mixing chitosan with glacial acetic acid to obtain a chitosan solution; dissolving the carboxylated graphene oxide in water and mixing it with the chitosan solution, followed by stirring to obtain the three-dimensional photocatalytic sponge block. The carboxylated graphene oxide (GO-COOH) of this invention exhibits extremely sensitive selective adsorption. Utilizing its overall mild photocatalytic performance, it achieves photochemical adsorption, effectively and selectively recovering various rare earth elements. Furthermore, this invention employs chitosan (CS) as the three-dimensional framework of the carboxylated graphene oxide, further enhancing its adsorption capacity. Moreover, it prepares a functional photocatalytic material with controllable shape and size, applicable to self-made continuous flow photocatalytic devices for continuous photocatalytic recovery. Furthermore, three-dimensional photocatalytic sponges of different sizes and shapes can be prepared according to the functional shapes of different devices, greatly enhancing and broadening the application depth and scope of three-dimensional photocatalytic sponges. In addition, this method improves the high-value utilization of graphite anodes in waste lithium batteries. By constructing a "recycling-regeneration-application" closed loop, it not only achieves full component resource utilization but also unlocks its enormous application potential in high-end materials and green recycling. Simultaneously, the three-dimensional photocatalytic sponge blocks rely on light energy to achieve green recovery of rare earth elements.

[0052] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape, characterized in that, Including the following steps: A modified Hummer's method was used to convert graphite powder in waste lithium batteries into graphene oxide. The graphene oxide was mixed with NaOH and chloroacetic acid, and then subjected to ultrasonic treatment to obtain carboxylated graphene oxide. Chitosan was mixed with glacial acetic acid to obtain a chitosan solution; The carboxylated graphene oxide was dissolved in water and then mixed with the chitosan solution. After stirring, a three-dimensional photocatalytic sponge block was obtained.

2. The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape according to claim 1, characterized in that, The step of converting graphite powder in spent lithium batteries into graphene oxide using the modified Hummer's method includes: The graphite powder from the waste lithium battery was mixed with sodium nitrate and sulfuric acid in an ice-water bath to obtain the first mixed solution. The first mixed solution is mixed with potassium permanganate, stirred, and then heated to 35℃-40℃ and maintained for 1h-2h to obtain the second mixed solution. Deionized water was added to the second mixed solution, the temperature was raised to 85℃-95℃ and the reaction was maintained for 1-2 hours, and then H2O2 was added to obtain graphene oxide.

3. The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape according to claim 2, characterized in that, The mass ratio of the graphite powder to the sodium nitrate is (2-3):

1.

4. The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape according to claim 1, characterized in that, The mass ratio of the graphene oxide to the NaOH and the chloroacetic acid is 1:(25-35):(20-30).

5. The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape according to claim 1, characterized in that, The concentration of the chitosan solution is 4 mg / mL to 7 mg / mL.

6. The method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape according to claim 1, characterized in that, The stirring process involves stirring with an oscillator at a speed of 500 rpm to 700 rpm for 10 to 20 minutes.

7. A three-dimensional photocatalytic sponge block with controllable size and shape, characterized in that, It is prepared using the method for preparing a three-dimensional photocatalytic sponge block with controllable size and shape as described in any one of claims 1-6.

8. The application of a three-dimensional photocatalytic sponge block with controllable size and shape as described in claim 7 in a rare earth element photocatalytic recovery device.

9. The application according to claim 8, characterized in that, The rare earth element photocatalytic recovery device includes: a plurality of reaction chambers with cylindrical slots, an excitation light source disposed in the cylindrical slots, a reaction pipe for connecting the plurality of reaction chambers in series, and a power pump disposed on a section of the reaction pipe; a three-dimensional photocatalytic sponge block matching the shape of the cylindrical slot is disposed in the cylindrical slot.

10. The application according to claim 8, characterized in that, The rare earth elements include one or more of Pr, Fe, Ce, and Gd.

Images