Nickel-cobalt-carbon composite material for adsorbing dye and preparation method thereof

Abstract

The application discloses a nickel-cobalt-carbon composite material for adsorbing dyes and a preparation method thereof, and relates to the technical field of material engineering. In view of the problems of low adsorption efficiency and narrow applicability of traditional adsorption materials, the nickel-cobalt-carbon composite material is prepared by taking maleic hydrazide as an organic ligand, taking cobalt salt and nickel salt as metal sources, preparing a MOFs precursor through a solvothermal reaction, and then performing high-temperature carbonization treatment in an inert gas atmosphere. The material is optimized through the synergistic effect of the bimetallic nickel-cobalt and the carbonization structure, and the adsorption performance on dye wastewater is significantly improved, the material exhibits high adsorption capacity and wide-spectrum applicability, and the adsorption process is rapid and stable. The preparation process is simple and controllable, the cost is low, and the material can be produced on a large scale, so that an efficient, environmentally-friendly and economical solution is provided for industrial dye wastewater treatment, and the material has a wide industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of materials engineering technology, and in particular to a nickel-cobalt-carbon composite material for adsorbing dyes and its preparation method. Background Technology

[0002] With industrial development, dyes are increasingly used in textiles, printing, cosmetics, and other fields, providing convenience for production and daily life. However, the subsequent treatment of these dyes is becoming increasingly serious. Large quantities of untreated dyes enter the water cycle directly. Because dyes are generally difficult to degrade and have a certain degree of toxicity, they not only disrupt the ecological balance but also pose a serious threat to human health. Therefore, the efficient removal of dyes from water has become a pressing research hotspot in the environmental field.

[0003] In the development of dye adsorption materials, metal-organic frameworks (MOFs) have become ideal substrates for dye adsorption due to their large specific surface area and regular crystal structure. By combining metal elements with organic ligands and then carbonizing the resulting MOFs, high-performance metal-carbon composite materials can be further prepared. This approach effectively achieves the synergistic combination of metal compounds and carbon materials, and the resulting materials typically possess excellent dye adsorption performance. Furthermore, the preparation process is relatively simple and cost-controllable, facilitating large-scale production and providing a feasible direction for solving dye wastewater treatment problems.

[0004] However, common dye adsorbents often suffer from limitations such as adsorbing only a single dye, low adsorption capacity, and consequently, limited application scenarios. Therefore, developing an adsorbent with a simple synthesis process, high adsorption capacity, and broad applicability for the efficient removal of dyes from wastewater has become a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a nickel-cobalt-carbon composite material for adsorbing dyes and its preparation method, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of this invention is to provide the application of maleic hydrazine as an organic ligand in the preparation of metal-organic framework materials.

[0008] The second technical solution of the present invention provides a metal-organic framework material, which uses maleic hydrazine as an organic ligand and cobalt and nickel as coordination metals.

[0009] The third technical solution of the present invention is to provide the application of the above-mentioned metal-organic framework material in the preparation of carbide metal-organic framework materials for the adsorption and removal of dyes in wastewater.

[0010] Fourth technical solution of the present invention: A method for preparing a nickel-cobalt-carbon composite material for adsorbing dyes, comprising the following steps:

[0011] A mixed solution of cobalt salt, nickel salt and maleic hydrazine was reacted at 120-180℃ for 12-20 h, and the metal-organic framework material was obtained by separation, washing and drying.

[0012] The metal-organic framework material was carbonized in an inert gas atmosphere at 600–900 °C for 2–4 h to obtain a nickel-cobalt-carbon composite material.

[0013] As a further preferred embodiment of the present invention, the preparation method includes the following steps:

[0014] Cobalt salt and nickel salt are dissolved in a solvent to obtain solution A; maleic hydrazine is dissolved in a solvent to obtain solution B;

[0015] Solution A and solution B are mixed and reacted at 120-180℃ for 12-20 hours. After separation, washing, and drying, the resulting material is a metal-organic framework.

[0016] The metal-organic framework material was carbonized at 600–900 °C for 2–4 h in an inert gas atmosphere to obtain a nickel-cobalt-carbon composite material.

[0017] As a further preferred embodiment of the present invention, the cobalt salt is cobalt acetate or cobalt nitrate, and the nickel salt is nickel acetate or nickel nitrate.

[0018] As a further preferred embodiment of the present invention, the molar ratio of the cobalt salt, nickel salt and maleic hydrazine is 0.5~1.5:0.5~1.5:3~9.

[0019] As a further preferred embodiment of the present invention, the inert gas is nitrogen or argon.

[0020] Fifth technical solution of the present invention: providing a nickel-cobalt-carbon composite material for adsorbing dyes prepared by the above preparation method.

[0021] This invention utilizes a novel organic ligand, maleic hydrazine, demonstrating its potential for synthesizing metal-organic frameworks (MOFs). Further carbonization of the prepared MOFs yields a carbon material, which exhibits excellent adsorption performance for anionic dyes (such as Congo Red (CR) and methyl orange (MO)) and cationic dyes (such as malachite green (MG) and methylene blue (MB)). Specifically, the organic ligand used in this invention is key to achieving efficient adsorption: its molecular structure provides multiple adsorption sites, laying the foundation for adsorption; simultaneously, the two metal elements Co and Ni further supplement the adsorption sites, and cobalt and nickel ions can form stable chelates with specific functional groups (such as carboxyl and amino groups) in dye molecules. This selective adsorption capacity is significantly superior to other metal ions, enhancing the material's binding ability to dyes. Finally, after carbonization to optimize the material structure, a nickel-cobalt-carbon composite material with good adsorption performance for various dyes was successfully prepared.

[0022] The sixth technical solution of the present invention: providing the application of the above-mentioned nickel-cobalt-carbon composite material for adsorbing dyes in the adsorption and removal of dyes in wastewater.

[0023] As a further preferred embodiment of the present invention, the wastewater dye includes anionic dyes and / or cationic dyes.

[0024] As a further preferred embodiment of the present invention, the wastewater dye includes one or more of malachite green, methylene blue, Congo red, and methyl orange.

[0025] The present invention discloses the following technical effects:

[0026] This invention provides a nickel-cobalt-carbon composite material, which uses maleic hydrazine as an organic ligand and cobalt and nickel salts as metal sources to generate metal-organic framework (MOF) materials through a solvothermal reaction, and successfully prepares a nickel-cobalt-carbon composite material with a unique structure through a high-temperature carbonization process in an inert gas atmosphere.

[0027] The nickel-cobalt-carbon composite material of this invention exhibits significant advantages in terms of technical performance: on the one hand, its bimetallic (nickel-cobalt) synergistic effect and optimized carbonization structure design significantly improve the adsorption performance of various dyes (such as malachite green, methyl orange, etc.), not only showing high adsorption capacity but also a broad adsorption range, breaking through the limitations of single dye adsorption; on the other hand, the process is simple and cost-controllable, especially in the solvothermal reaction and high-temperature carbonization steps, the material structure is precisely controlled, further enhancing the adsorption efficiency and material stability.

[0028] Compared to traditional adsorption materials, which suffer from low adsorption efficiency and narrow applicability, this invention provides an efficient, economical, and universally applicable technical solution for industrial-scale dye wastewater treatment through dual innovations in structural design and process optimization. It effectively solves the core bottleneck of existing technologies in environmental protection applications and has broad prospects for industrial application. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The images show SEM images of the metal-organic framework material (marked as before carbonization) and the nickel-cobalt-carbon composite material (marked as after carbonization) in Examples 1-3 of this invention.

[0031] Figure 2 The images show SEM images of the adsorbent materials prepared in Comparative Examples 1-6 of this invention.

[0032] Figure 3 Comparison chart of the adsorption performance of nickel-cobalt-carbon composite materials prepared in Examples 1-3 and adsorption materials prepared in Comparative Examples 1-6 for malachite green (MG) dye.

[0033] Figure 4 Comparison chart of the adsorption performance of nickel-cobalt-carbon composite materials prepared in Examples 1-3 and adsorption materials prepared in Comparative Examples 1-6 for methyl orange (MO) dye.

[0034] Figure 5 Comparison chart of the adsorption performance of the nickel-cobalt-carbon composite materials prepared in Examples 1-3 and the adsorption materials prepared in Comparative Examples 1-6 for methylene blue (MB) dye.

[0035] Figure 6 Comparison chart of the adsorption performance of Congo Red (CR) dye by the nickel-cobalt-carbon composite materials prepared in Examples 1-3 and the adsorption materials prepared in Comparative Examples 1-6.

[0036] Figure 7 The graphs show the performance test results of the nickel-cobalt-carbon composite materials prepared in Examples 1-3 of this invention for the simultaneous adsorption of two dyes, methylene blue and Congo red.

[0037] Figure 8 The graphs show the cyclic adsorption performance of malachite green dye on the nickel-cobalt-carbon composite materials prepared in Examples 1-3 of this invention.

[0038] Figure 9The graphs show the cyclic adsorption performance of methyl orange dye on the nickel-cobalt-carbon composite materials prepared in Examples 1-3 of this invention. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0045] The first aspect of this invention is to provide the application of maleic hydrazine as an organic ligand in the preparation of metal-organic framework materials.

[0046] A second aspect of the present invention provides a metal-organic framework material, which uses maleic hydrazine as an organic ligand and cobalt and nickel as metal ions.

[0047] A third aspect of the present invention is to provide the application of the above-mentioned metal-organic framework material in the preparation of carbide metal-organic framework materials for the adsorption and removal of dyes from wastewater.

[0048] Fourth aspect of the present invention: Provides a method for preparing a nickel-cobalt-carbon composite material for adsorbing dyes, comprising the following steps:

[0049] A mixed solution of cobalt salt, nickel salt and maleic hydrazine was reacted at 120-180℃ for 12-20 h, and the metal-organic framework material was obtained by separation, washing and drying.

[0050] The metal-organic framework material was carbonized at 600–900 °C for 2–4 h in an inert gas atmosphere to obtain a nickel-cobalt-carbon composite material.

[0051] Furthermore, the preparation method includes the following steps:

[0052] A more preferred preparation process for the nickel-cobalt-carbon composite material of the present invention includes the following steps:

[0053] (1) Add cobalt salt and nickel salt to a certain amount of N,N-dimethylformamide and dissolve by sonication for 8-12 min to obtain a clear solution A. The metal salt can be cobalt acetate, nickel acetate or cobalt nitrate, nickel nitrate;

[0054] (2) Add maleic hydrazine to a certain amount of N,N-dimethylformamide at a weight ratio of 1:25-35, and stir and mix it evenly for 8-12 minutes to obtain a clear solution B;

[0055] (3) Mix solution A and solution B and mix them evenly. Then keep them in a reaction vessel with a polytetrafluoroethylene liner at a temperature of 120-180°C for 12-20 hours. Then cool them to room temperature and centrifuge them. The separated precipitate is first washed with N,N-dimethylformamide 2-4 times and then washed with ethanol 2-4 times. The washed precipitate is then dried in an oven at a temperature of 40-60°C for 24 hours to obtain the metal-organic framework material.

[0056] (4) The metal-organic framework material prepared in step (3) is heated in an inert gas to a temperature of 600-900°C and held at this temperature for 2-4 hours. The inert gas is nitrogen or argon, to obtain the nickel-cobalt-carbon composite material.

[0057] In step (3), when the separated precipitate is washed with N,N-dimethylformamide, the ratio of precipitate in grams to N,N-dimethylformamide in milliliters is 1:5 to 20.

[0058] In step (3), when the separated precipitate is washed with ethanol, the ratio of precipitate in grams to ethanol in milliliters is 1:5 to 20.

[0059] Furthermore, the cobalt salt is cobalt acetate or cobalt nitrate, and the nickel salt is nickel acetate or nickel nitrate.

[0060] Furthermore, the inert gas is either nitrogen or argon.

[0061] Fifth aspect of the present invention: providing a nickel-cobalt-carbon composite material for adsorbing dyes prepared by the above preparation method.

[0062] This invention utilizes a novel organic ligand, maleic hydrazine, demonstrating its potential for synthesizing metal-organic frameworks (MOFs). Further carbonization of the prepared MOFs yields a carbon material, which exhibits excellent adsorption performance for various dyes. Specifically, the organic ligand used in this invention is key to achieving efficient adsorption: its molecular structure provides multiple adsorption sites, laying the foundation for adsorption; simultaneously, the two metal elements Co and Ni further supplement these adsorption sites, and cobalt and nickel ions can form stable chelates with specific functional groups (such as carboxyl and amino groups) in dye molecules. This selective adsorption capacity is significantly superior to other metal ions, enhancing the material's binding ability to dyes. Finally, after carbonization to optimize the material structure, a nickel-cobalt-carbon composite material with good adsorption performance for various dyes was successfully prepared.

[0063] The sixth aspect of the present invention is to provide the application of the nickel-cobalt-carbon composite material for adsorbing dyes as described above in the adsorption and removal of dyes from wastewater.

[0064] Furthermore, the wastewater dyes include anionic dyes and / or cationic dyes.

[0065] Furthermore, the wastewater dye includes one or more of malachite green, methylene blue, Congo red, and methyl orange.

[0066] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0067] Example 1

[0068] This embodiment provides a method for preparing a nickel-cobalt-carbon composite material for adsorbing dyes, the steps of which are as follows:

[0069] (1) Weigh out 3 mmol of cobalt acetate, 3 mmol of nickel acetate and 12 mmol of maleic hydrazide respectively;

[0070] (2) Add cobalt acetate and nickel acetate to N,N-dimethylformamide (weight ratio 1:1:20), and dissolve by sonication for 10 min to obtain clear solution A;

[0071] (3) Add maleic hydrazine to N,N-dimethylformamide (weight ratio 1:30), and then mix by stirring for 10 min to ensure uniform mixing, and finally obtain a clear solution B;

[0072] (4) Mix the prepared solution A and solution B thoroughly and stir until the system is homogeneous; transfer the mixed solution to a reaction vessel with a polytetrafluoroethylene liner and keep it at 150°C for 20 h; after the reaction, cool naturally to room temperature, separate by centrifugation, and collect the precipitate; wash the separated precipitate: first wash it 3 times with N,N-dimethylformamide, the ratio of precipitate (in grams) to N,N-dimethylformamide (in milliliters) during the washing process is 1:10; then wash it 3 times with ethanol, the ratio of precipitate (in grams) to ethanol (in milliliters) during the washing process is also 1:10. Then dry the washed precipitate in an oven at 45°C for 24 h to obtain the metal-organic framework material;

[0073] (5) The metal-organic framework material prepared in step (4) is placed in a nitrogen protective atmosphere, heated to 700°C, and kept at this temperature for 3 hours; after the heat preservation is completed, it is naturally cooled to obtain the target product nickel-cobalt-carbon composite material.

[0074] Example 2

[0075] This embodiment provides a method for preparing a nickel-cobalt-carbon composite material for adsorbing dyes, the steps of which are as follows:

[0076] (1) Weigh out 3 mmol of cobalt nitrate, 3 mmol of nickel nitrate and 12 mmol of maleic hydrazine respectively;

[0077] (2) Add cobalt nitrate and nickel nitrate to N,N-dimethylformamide (weight ratio 1:1:20), and dissolve by sonication for 10 min to obtain clear solution A;

[0078] (3) Add maleic hydrazine to N,N-dimethylformamide (weight ratio 1:30); then mix by stirring for 10 min to ensure uniform mixing, and finally obtain a clear solution B;

[0079] (4) Mix the prepared solution A and solution B thoroughly and stir until the system is homogeneous; transfer the mixed solution to a reaction vessel with a polytetrafluoroethylene liner and keep it at 150°C for 20 h; after the reaction, cool naturally to room temperature, separate by centrifugation, and collect the precipitate; wash the separated precipitate: first wash it 3 times with N,N-dimethylformamide, the ratio of precipitate (in grams) to N,N-dimethylformamide (in milliliters) during the washing process is 1:10; then wash it 3 times with ethanol, the ratio of precipitate (in grams) to ethanol (in milliliters) during the washing process is also 1:10. Then dry the washed precipitate in an oven at 45°C for 24 h to obtain the metal-organic framework material;

[0080] (5) The metal-organic framework material prepared in step (4) is placed in a nitrogen protective atmosphere, heated to 700°C, and kept at this temperature for 3 hours; after the heat preservation is completed, it is naturally cooled to obtain the target product nickel-cobalt-carbon composite material.

[0081] Example 3

[0082] This embodiment provides a method for preparing a nickel-cobalt-carbon composite material for adsorbing dyes, the steps of which are as follows:

[0083] (1) Weigh out 3 mmol of cobalt nitrate, 3 mmol of nickel nitrate and 12 mmol of maleic hydrazine respectively;

[0084] (2) Add cobalt nitrate and nickel nitrate to N,N-dimethylformamide (weight ratio 1:1:20), and dissolve by sonication for 10 min to obtain clear solution A;

[0085] (3) Add maleic hydrazine to N,N-dimethylformamide (weight ratio 1:30), and then mix by stirring for 10 min to ensure uniform mixing, and finally obtain a clear solution B;

[0086] (4) Mix the prepared solution A and solution B thoroughly and stir until the system is homogeneous; transfer the mixed solution to a reaction vessel with a polytetrafluoroethylene liner and keep it at 180°C for 20 h; after the reaction, cool naturally to room temperature, separate by centrifugation, and collect the precipitate; wash the separated precipitate: first wash it 3 times with N,N-dimethylformamide, the ratio of precipitate (in grams) to N,N-dimethylformamide (in milliliters) during the washing process is 1:10; then wash it 3 times with ethanol, the ratio of precipitate (in grams) to ethanol (in milliliters) during the washing process is also 1:10. Then dry the washed precipitate in an oven at 45°C for 24 h to obtain the metal-organic framework material;

[0087] (5) The metal-organic framework material prepared in step (4) is placed in a nitrogen protective atmosphere, heated to 600°C, and kept at this temperature for 3 hours; after the heat preservation is completed, it is naturally cooled to obtain the target product nickel-cobalt-carbon composite material.

[0088] Comparative Example 1

[0089] The only difference from Example 1 is that a single metal salt, cobalt acetate, is used.

[0090] The preparation method steps are as follows:

[0091] (1) Weigh out 3 mmol of cobalt acetate and 9 mmol of maleic hydrazine respectively;

[0092] (2) Add cobalt acetate to N,N-dimethylformamide (weight ratio 1:20) and dissolve by sonication for 10 min to obtain clear solution A;

[0093] Steps (3)-(5) are the same as in Example 1.

[0094] Comparative Example 2

[0095] The only difference from Example 1 is that a single metal salt, nickel acetate, is used.

[0096] The preparation method steps are as follows:

[0097] (1) Weigh out 3 mmol of nickel acetate and 9 mmol of maleic hydrazide respectively;

[0098] (2) Add nickel acetate to N,N-dimethylformamide (weight ratio 1:20) and dissolve by sonication for 10 min to obtain clear solution A;

[0099] Steps (3)-(5) are the same as in Example 1.

[0100] Comparative Example 3

[0101] The only difference from Example 1 is that step (5) is not performed.

[0102] Comparative Example 4

[0103] The only difference from Example 1 is that 1,4-phthalic acid is used as the organic ligand. The preparation steps are as follows:

[0104] (1) Weigh out 3 mmol of cobalt acetate, 3 mmol of nickel acetate and 12 mmol of 1,4-phthalic acid respectively;

[0105] (2) Add cobalt acetate and nickel acetate to N,N-dimethylformamide in a weight ratio of 1:1:20, and dissolve by sonication for 10 min to obtain a clear solution A;

[0106] (3) Add 1,4-phthalic acid to N,N-dimethylformamide (weight ratio 1:30), and then mix by stirring for 10 minutes to ensure uniform mixing, and finally obtain a clear solution B;

[0107] Steps (4)-(5) are the same as in Example 1.

[0108] Comparative Example 5

[0109] The only difference from Example 1 is the use of 2-aminoterephthalic acid as the organic ligand. The preparation steps are as follows:

[0110] (1) Weigh out 3 mmol of cobalt acetate, 3 mmol of nickel acetate, and 12 mmol of 2-aminoterephthalic acid respectively;

[0111] (2) Cobalt acetate and nickel acetate were added to a certain amount of N,N-dimethylformamide in a weight ratio of 1:1:20, and the mixture was dissolved by sonication for 10 min to obtain a clear solution A;

[0112] (3) Add 2-aminoterephthalic acid to N,N-dimethylformamide (weight ratio 1:30), and then mix by stirring for 10 min to ensure uniform mixing, and finally obtain a clear solution B;

[0113] Steps (4)-(5) are the same as in Example 1.

[0114] Comparative Example 6

[0115] The only difference from Example 1 is that cerium nitrate is used as the coordinating metal. The preparation steps are as follows:

[0116] The preparation method steps are as follows:

[0117] (1) Weigh out 3 mmol of cerium nitrate and 9 mmol of maleic hydrazine respectively;

[0118] (2) Add cerium nitrate to N,N-dimethylformamide (weight ratio 1:20) and dissolve by sonication for 10 min to obtain clear solution A;

[0119] Steps (3)-(5) are the same as in Example 1.

[0120] Figure 1 The images show SEM images of the metal-organic framework material (marked as before carbonization) and the nickel-cobalt-carbon composite material (marked as after carbonization) in Examples 1-3 of this invention.

[0121] Figure 2 The images show SEM images of the adsorbent materials prepared in Comparative Examples 1-6 of this invention.

[0122] Effect verification example

[0123] 1. Verification of dye adsorption performance

[0124] The nickel-cobalt-carbon composite materials prepared in Examples 1-3 and the adsorbent materials prepared in Comparative Examples 1-6 were used as adsorbents for adsorption performance testing. The concentration of the adsorbent in the system was set to 1 g / L.

[0125] To evaluate the adsorption performance of the dyes, aqueous solutions of four target dyes were prepared: malachite green (MG) at an initial concentration of 3000 mg / L, methylene blue (MB) at an initial concentration of 500 mg / L, methyl orange (MO) at an initial concentration of 50 mg / L, and Congo red (CR) at an initial concentration of 1500 mg / L. All adsorption reactions were carried out at a constant temperature of 25°C for a controlled reaction time of 3 hours to ensure that the adsorption process proceeded fully and reached adsorption equilibrium. Figure 3 Comparison chart of the adsorption performance of nickel-cobalt-carbon composite materials prepared in Examples 1-3 and adsorption materials prepared in Comparative Examples 1-6 for malachite green (MG) dye.

[0126] from Figure 3 As can be seen, the adsorption capacity of the nickel-cobalt-carbon composite materials in Examples 1-3 for MG dye was close to 3000 mg / g after 180 min, while the adsorption capacity of the adsorbent materials in Comparative Examples 1-3 was about 2200 mg / g, and the adsorption capacities of the adsorbent materials in Comparative Examples 4 and 5 were about 2563 mg / g and 1988 mg / g, respectively, demonstrating the superiority of the maleic hydrazine ligand. The adsorption capacity of Comparative Example 6 for MG dye was about 2400 mg / g, demonstrating the superiority of nickel and cobalt as coordination metals.

[0127] Figure 4 Comparison chart of the adsorption performance of nickel-cobalt-carbon composite materials prepared in Examples 1-3 and adsorption materials prepared in Comparative Examples 1-6 for methyl orange (MO) dye.

[0128] from Figure 4 As can be seen, the adsorption capacity of the nickel-cobalt-carbon composite materials in Examples 1-3 for MO dye was close to 50 mg / g after 180 min, while the adsorption capacities of the adsorbent materials in Comparative Examples 1-3 were approximately 41 mg / g, 40 mg / g, and 46 mg / g, respectively. The adsorption capacities of the adsorbent materials in Comparative Examples 4 and 5 were approximately 31 mg / g and 3 mg / g, respectively. The adsorption of MO dye by these materials further demonstrates the superiority of the maleic hydrazine ligand. The adsorption capacity of MO dye in Comparative Example 6 was approximately 25 mg / g, demonstrating the superiority of nickel and cobalt as coordination metals.

[0129] Figure 5Comparison chart of the adsorption performance of the nickel-cobalt-carbon composite materials prepared in Examples 1-3 and the adsorption materials prepared in Comparative Examples 1-6 for methylene blue (MB) dye.

[0130] from Figure 5 As can be seen, the adsorption capacity of the nickel-cobalt-carbon composite materials in Examples 1-3 for MB dye was close to 310 mg / g after 180 min, while the adsorption capacities of the adsorbent materials in Comparative Examples 1-3 were approximately 223 mg / g, 231 mg / g, and 282 mg / g, respectively. The adsorption capacity of MB dye in Comparative Example 4 was approximately 249 mg / g, and Comparative Example 5 showed almost no adsorption of MB dye, demonstrating the superiority of the maleic hydrazine ligand. The adsorption capacity of dye in Comparative Example 6 was approximately 153 mg / g, demonstrating the superiority of nickel and cobalt as coordination metals.

[0131] Figure 6 Comparison chart of the adsorption performance of Congo Red (CR) dye by the nickel-cobalt-carbon composite materials prepared in Examples 1-3 and the adsorption materials prepared in Comparative Examples 1-6.

[0132] from Figure 6 As can be seen, the adsorption capacity of the nickel-cobalt-carbon composite materials in Examples 1-3 for CR dyes was close to 1500 mg / g after 180 min, while the adsorption capacities of the adsorbent materials in Comparative Examples 1-3 were approximately 1250 mg / g, 1200 mg / g, and 1300 mg / g, respectively. Comparative Example 4 showed almost no adsorption of CR dyes, demonstrating the superiority of the maleic hydrazine ligand. The adsorption capacity of the adsorbent material in Comparative Example 5 was similar to that in Examples 1-3. The adsorption capacity of the dye in Comparative Example 6 was approximately 1300 mg / g, demonstrating the superiority of nickel and cobalt as coordination metals.

[0133] Equal volumes of 1000 mg / L methylene blue and 1000 mg / L Congo red solution were mixed to obtain a mixed solution. 20 mg of the nickel-cobalt-carbon composite material from Examples 1-3 was added to 20 mL of the mixed solution, with the solution without the nickel-cobalt-carbon composite material serving as a blank control (labeled as blank). After shaking at room temperature for 3 hours, the solution was removed and its absorbance was measured. Figure 7 Figure 7 shows the performance test results of simultaneous adsorption of methylene blue and Congo red in Examples 1-3. The results show that the nickel-cobalt-carbon composite materials of Examples 1-3 still have excellent adsorption performance in the mixed solution of methylene blue and Congo red, indicating that the material can still effectively adsorb dyes with different charge types in complex dye systems, further expanding its application scenarios.

[0134] 2. Verification of Cyclic Adsorption Performance

[0135] 20 mg of the nickel-cobalt-carbon composite material from Examples 1-3 was added to 20 mL of malachite green solution with a concentration of 1000 mg / L. After adsorption, the dye was desorbed using ethanol. After three cycles, the adsorption performance was as follows: Figure 8 As shown in the figure. The results indicate that after three cycles of testing, Examples 1-3 still maintained a high adsorption efficiency of over 90% for malachite green dye. This demonstrates that the material exhibits good cycle stability in the adsorption of cationic dyes, allowing for repeated use and reducing processing costs.

[0136] 20 mg of the nickel-cobalt-carbon composite material from Examples 1-3 was added to 20 mL of methyl orange solution with a concentration of 50 mg / L. After adsorption, the dye was desorbed using ethanol. After three cycles, the adsorption performance was as follows: Figure 9 As shown in the figure. The results indicate that after three cycles of testing, Examples 1-3 still maintained a high adsorption efficiency for methyl orange dye, approaching 90% or higher. This further demonstrates that the material also exhibits excellent recyclability in the adsorption of anionic dyes, providing an important guarantee for its industrial application.

[0137] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. Use of a nickel-cobalt-carbon composite material in the adsorptive removal of dyes from wastewater, characterized in that, The preparation method of the nickel-cobalt-carbon composite material comprises the following steps: a mixed solution of a cobalt salt, a nickel salt and malehydrazide is subjected to a solvothermal reaction at 120-180 DEG C for 12-20 h, and then separated, washed and dried to obtain a metal organic framework material; the metal organic framework material is carbonized at 600-900 DEG C for 2-4 h in an inert gas atmosphere to obtain the nickel-cobalt-carbon composite material; the cobalt salt is cobalt acetate or cobalt nitrate, and the nickel salt is nickel acetate or nickel nitrate; the molar ratio of the cobalt salt, the nickel salt and malehydrazide is (0.5-1.5):(0.5-1.5):(3-9); the wastewater dye comprises one or more of malachite green, methylene blue, congo red and methyl orange.

2. Use according to claim 1, characterized in that, The preparation method of the nickel-cobalt-carbon composite material comprises the following steps: a cobalt salt and a nickel salt are dissolved in a solvent to obtain solution A; malehydrazide is dissolved in a solvent to obtain solution B; the solution A and the solution B are mixed, subjected to a solvothermal reaction at 120-180 DEG C for 12-20 h, and then separated, washed and dried to obtain a metal organic framework material; the metal organic framework material is carbonized at 600-900 DEG C for 2-4 h in an inert gas atmosphere to obtain a nickel-cobalt-carbon composite material.

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