Metal Co modified N-doped porous carbon electric adsorbent and preparation method thereof
By introducing Co/NC heterostructure and uniformly dispersed Co active centers into the porous carbon framework, the problem of insufficient distribution of porous carbon materials at active sites and ion selectivity is solved, the effect of efficient nitrate enrichment is achieved, and the stability and anti-interference ability of the material are improved.
Patent Information
- Application Number
- CN202510592705.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-09
- Publication Date
- 2025-08-01
AI Technical Summary
The existing porous carbon materials have shortcomings in the distribution of active sites and ion selectivity, and it is difficult to efficiently enrich target ions. Metal-supported carbon materials also have problems in the uniform dispersion of metal particles and the material cycle stability, which limits their overall adsorption efficiency and long-term use effect.
Co/NC heterostructure was introduced into the porous carbon framework, ZIF-8 was grown as a template through ZnO nanoarrays, electron-deficient Co activity center was constructed, and polyvinylpyrrolidone (PVP) coordination and high-temperature carbonization strategies were adopted to make metal nanoparticles highly uniformly disperse within the carbon framework, forming a stable heterostructure.
The electrostatic adsorption capacity between the material surface and nitrate is significantly improved, the effective charge distribution of the adsorbent is optimized, the ion enrichment performance and anti-competitive interference ability are enhanced, and the recycling life of the material is improved.
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Figure CN120393945A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electroadsorption materials, and particularly relates to a metal Co-modified N-doped porous carbon electroadsorbent and a preparation method thereof. Background Art
[0002] With the continuous development of industry and agriculture, the accumulation of nitrate ions and other substances in water bodies poses a serious threat to the ecological system and drinking water safety. Existing processes such as biological methods, chemical reduction methods, and membrane separation methods still have deficiencies in terms of operating costs, operation difficulties, and secondary pollution. To achieve the goal of efficient and sustainable water purification, electrochemical adsorption technology has received attention. Porous carbon-based electrodes have significant advantages in this field due to their large specific surface area, good electrical conductivity, etc. However, pure carbon materials still have deficiencies in the distribution of active sites and ion selectivity, and it is difficult to efficiently enrich target ions. Although metal-loaded carbon materials can enhance the ion adsorption ability to a certain extent, the main problems faced are the uniform dispersion of metal particles and the cycle stability of the materials, which limit their overall adsorption efficiency and long-term use effect. Summary of the Invention
[0003] The purpose of the present invention is to provide a metal Co-modified N-doped porous carbon electroadsorbent and a preparation method thereof, introducing a Co / NC heterostructure into the porous carbon framework to increase the accessible area of the microporous structure and enhance the interaction between active sites and target ions.
[0004] To achieve the above purpose, the technical solution provided by the present invention is as follows:
[0005] The first aspect of the present application provides a preparation method of a metal Co-modified N-doped porous carbon electroadsorbent, including the following steps:
[0006] S1: Immerse a carbon felt in a zinc salt solution, and react to obtain a ZnO-loaded carbon felt, denoted as ZnO / CF material;
[0007] S2: Immerse the ZnO / CF material in a carbon source solution, and react and carbonize to obtain ZnO-ZIF-8-derived porous nitrogen-doped carbon, denoted as NC material;
[0008] S3: Immerse the NC material in a mixed solution of polyvinylpyrrolidone and a Co metal salt, and react and carbonize to obtain a metal Co-modified N-doped porous carbon electroadsorbent, denoted as Co / NC material.
[0009] To optimize the above technical solution, the specific measures taken also include:
[0010] The zinc salt selected is one of zinc acetate dihydrate or zinc nitrate hexahydrate.
[0011] In step S1, the immersion of the carbon felt in the zinc salt solution includes:
[0012] Step S1.1: Immerse the carbon felt in a methanol solution of zinc salt, let it stand still, and then heat and dry it.
[0013] Step S1.2: Immerse the carbon felt in a mixed aqueous solution of zinc salt and hexamethylenetetramine. After stirring, heating, washing, and drying, the ZnO / CF material is obtained.
[0014] Furthermore, in the methanol solution of zinc salt, the molar concentration of zinc element is 0.015 - 0.025 mol / L; in the mixed aqueous solution of zinc salt and hexamethylenetetramine, the molar concentration of zinc element is 0.04 - 0.06 mol / L, and the concentration of hexamethylenetetramine is 0.005 - 0.01 g / mL.
[0015] In step S2, immerse the ZnO / CF material in the carbon source solution. After stirring, heating, washing, drying, and high-temperature carbonization, the NC material is obtained; where the heating temperature is 60 - 80 °C, the heating time is 1.5 - 2.5 hours; the temperature of high-temperature carbonization is 870 - 930 °C, and the carbonization time is 1.5 - 2.5 hours.
[0016] The described carbon source solution uses a 2-methylimidazole methanol solution.
[0017] Furthermore, the concentration of the described carbon source solution is 0.12 - 0.16 g / mL.
[0018] In step S3, immerse the NC material in a mixed aqueous solution of polyvinylpyrrolidone and Co metal salt. After stirring, washing, drying, and high-temperature carbonization treatment, the Co / NC material is obtained; where the temperature of high-temperature carbonization is 870 - 930 °C, and the carbonization time is 1.5 - 2.5 hours.
[0019] Furthermore, in the mixed solution of polyvinylpyrrolidone and Co metal salt, the concentration of polyvinylpyrrolidone is 0.015 - 0.025 g / mL, and the concentration of Co element in the Co metal salt is 0.018 - 0.022 mol / L.
[0020] The second aspect of this application provides a metal Co-modified N-doped porous carbon electroadsorbent, which is prepared by the above method.
[0021] Compared with the prior art, the beneficial effects of the present invention are:
[0022] The present invention significantly improves the electrostatic adsorption ability between the material surface and nitrate by introducing Co / NC heterostructure into the porous carbon framework and constructing electron-deficient Co active centers; the present invention uses ZnO nanoray arrays as templates and Zn sources to grow ZIF-8, improving the accessibility of microporous active sites and optimizing the effective charge distribution of the adsorbent, thereby enhancing the ion enrichment performance of the adsorbent; the present invention realizes better loading of ZnO through a two-stage loading mechanism and the synergistic effect of "seed-induced - liquid phase epitaxy"; the present invention adopts a synergistic strategy of polyvinylpyrrolidone (PVP) coordination and high-temperature carbonization to highly uniformly disperse metal nanoparticles within the carbon framework, effectively enhancing the structural stability of the adsorbent and its cycle service life; the metal Co-modified N-doped porous carbon electroadsorbent of the present invention can preferentially enrich nitrate in multi-solute water bodies and has excellent anti-competitive interference ability. Description of the Drawings
[0023] Figure 1 It is the Raman spectrogram of ZnO-ZIF-8-derived N-doped porous carbon prepared by the present invention.
[0024] Figure 2 It is the schematic diagram of the adsorption capacity of ZnO-ZIF-8-derived N-doped porous carbon prepared by the present invention.
[0025] Figure 3 It is the XRD pattern of metal Co-modified N-doped porous carbon prepared by the present invention.
[0026] Figure 4 It is the schematic diagram of the adsorption capacity of metal Co-modified N-doped porous carbon prepared by the present invention.
[0027] Figure 5 It is the nitrogen adsorption and desorption isotherm of metal Co-modified N-doped porous carbon prepared by the present invention.
[0028] Figure 6 It is the schematic diagram of the adsorption capacity of different metal-modified N-doped porous carbons prepared by the present invention.
[0029] Figure 7 It is the schematic diagram of the adsorption capacity of different metal-modified N-doped porous carbons for multi-solutes prepared by the present invention.
[0030] Figure 8 It is the schematic diagram of the adsorption selectivity of different metal-modified N-doped porous carbons prepared by the present invention.
[0031] Figure 9 It is the schematic diagram of the adsorption cycle performance of metal Co-modified N-doped porous carbon prepared by the present invention. Detailed Embodiments
[0032] The above content of the present invention will be further described in detail below in the form of specific embodiments. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments. Any technology implemented based on the above content of the present invention belongs to the scope of the present invention.
[0033] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The reagents, methods, and equipment used are all conventional reagents, methods, and equipment in the technical field unless otherwise specified.
[0034] For the sake of simplicity, only some numerical values and optional ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded; and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded; the options in the optional range can also be combined arbitrarily.
[0035] Some of the terms in the present invention are explained as follows:
[0036] Accessibility: That is, reachability, the ability of the target ion to reach. In the present invention, by constructing a mesoporous-microporous interconnected structure, the accessibility of the micropores is increased, and the utilization rate of the active sites in the micropores is improved.
[0037] The present invention provides a preparation method of a metal Co-modified N-doped porous carbon electroadsorbent, including the following steps:
[0038] S1: Immerse the carbon felt in a zinc salt solution, and react to obtain ZnO-loaded carbon felt, denoted as ZnO / CF material;
[0039] S2: Immerse the ZnO / CF material in a carbon source solution, and react and carbonize to obtain ZnO-ZIF-8-derived porous nitrogen-doped carbon, denoted as NC material;
[0040] S3: Immerse the NC material in a mixed solution of polyvinylpyrrolidone and Co metal salt, and react and carbonize to obtain a metal Co-modified N-doped porous carbon electroadsorbent, denoted as Co / NC material.
[0041] The zinc salt is selected from one of zinc acetate dihydrate or zinc nitrate hexahydrate.
[0042] In step S1, immersing the carbon felt in the zinc salt solution includes:
[0043] Step S1.1: Immerse the carbon felt in a methanol solution of the zinc salt, let it stand, and then heat and dry;
[0044] Step S1.2: Immerse the carbon felt in a mixed aqueous solution of the zinc salt and hexamethylenetetramine, stir, heat, wash, and dry to obtain the ZnO / CF material.
[0045] The present invention achieves better loading of ZnO through two different zinc salt impregnations. The first impregnation is to pre-load some metallic Zn on the surface of carbon fibers. The pre-loading of zinc precursors on the surface of carbon fibers is achieved through the interfacial wetting effect of the zinc salt methanol solution. After heating, a metallic zinc seed layer is formed on the fiber surface, and this active interface significantly reduces the activation energy barrier for subsequent ZnO growth. The second constructed zinc salt - HMTA aqueous phase system undergoes a coordination hydrolysis reaction under thermodynamic regulation, and the directional self-assembly growth of ZnO is achieved by utilizing the slow-release base effect of hexamethylenetetramine.
[0046] This two-stage loading mechanism effectively solves the common problems of nanoparticle aggregation and weak interfacial binding force in traditional single loading through the synergistic effect of "seed induction - liquid phase epitaxy". The obtained ZnO / CF composite material exhibits highly oriented nanostructure characteristics and significantly enhanced interfacial charge transport performance.
[0047] In some embodiments, in the methanol solution of zinc salt, the molar concentration of zinc element is 0.015 - 0.025 mol / L; in the mixed aqueous solution of zinc salt and hexamethylenetetramine, the molar concentration of zinc element is 0.04 - 0.06 mol / L, and the concentration of hexamethylenetetramine is 0.005 - 0.01 g / mL.
[0048] In step S2, the ZnO / CF material is immersed in the carbon source solution, and the NC material is obtained through stirring, heating, washing, drying, and high-temperature carbonization. The heating temperature is 60 - 80 °C, and the heating time is 1.5 - 2.5 hours; the temperature of high-temperature carbonization is 870 - 930 °C, and the carbonization time is 1.5 - 2.5 hours.
[0049] The carbon source solution uses a 2-methylimidazole methanol solution.
[0050] In some embodiments, the concentration of the carbon source solution is 0.12 - 0.16 g / mL.
[0051] In step S3, the NC material is immersed in the mixed aqueous solution of polyvinylpyrrolidone and Co metal salt, and the Co / NC material is obtained through stirring, washing, drying, and high-temperature carbonization treatment. The temperature of high-temperature carbonization is 870 - 930 °C, and the carbonization time is 1.5 - 2.5 hours.
[0052] In some embodiments, in the mixed solution of polyvinylpyrrolidone and Co metal salt, the concentration of polyvinylpyrrolidone is 0.015 - 0.025 g / mL, and the concentration of Co element in the Co metal salt is 0.018 - 0.022 mol / L.
[0053] The present invention also provides a metal Co-modified N-doped porous carbon electroadsorbent, which is prepared by the above method.
[0054] The technical solution of the present invention will be further described in detail with reference to specific embodiments as follows:
[0055] (1) Preparation of ZnO-ZIF-8-derived nitrogen-doped porous carbon electroadsorbent and investigation of the concentration of the carbon source solution.
[0056] Example 1
[0057] (1) Dissolve 1.095 g of zinc acetate dihydrate in 250 mL of methanol. Immerse a 7 cm × 14 cm carbon felt (CF) in the methanol solution, take it out after standing for 30 minutes, lay it flat on a heating table, and heat it at 300 °C for 20 minutes.
[0058] (2) Dissolve 3.71 g of zinc nitrate hexahydrate and 1.75 g of hexamethylenetetramine in 125 mL of deionized water respectively. Pour the zinc nitrate solution into the hexamethylenetetramine solution and mix and stir for 20 minutes. Place the heated CF in the mixed solution and stir for 1 hour, and heat at 95 °C for 5 hours;
[0059] (3) Wash it 3 times with water and ethanol, and then dry it in a vacuum drying oven at 60 °C for 24 hours to obtain carbon felt loaded with ZnO, i.e., ZnO / CF;
[0060] (4) Dissolve 15 g of 2-methylimidazole in 250 mL of methanol. Immerse ZnO / CF in the 2-methylimidazole methanol solution and heat it at 70 °C for 2 hours;
[0061] (5) Wash it 3 times with water and ethanol, and then dry it in a vacuum drying oven at 60 °C for 24 hours to obtain ZnO-ZIF-8 / CF;
[0062] (6) Place the dried ZnO-ZIF-8 / CF in an N2 atmosphere and pyrolyze it at 900 °C for 2 hours with a heating rate of 5 °C / minute to obtain ZIF-8-derived nitrogen-doped porous carbon, denoted as NC-1.
[0063] Example 2
[0064] The solution of this example is basically the same as that of Example 1, except that in step (4), 25 g of 2-methylimidazole is dissolved in 250 mL of methanol, and ZnO / CF is immersed in the 2-methylimidazole methanol solution and heated at 70 °C for 2 hours.
[0065] The product obtained in this example is denoted as NC-2.
[0066] Example 3
[0067] The solution of this example is basically the same as that of Example 1, except that in step (4), 35 g of 2-methylimidazole is dissolved in 250 mL of methanol, and ZnO / CF is immersed in the 2-methylimidazole methanol solution and heated at 70 °C for 2 hours;
[0068] The product obtained in this example is denoted as NC-3.
[0069] Example 4
[0070] The solution of this example is basically the same as that of Example 1, except that in step (4), 45 g of 2-methylimidazole is dissolved in 250 mL of methanol, and ZnO / CF is immersed in the 2-methylimidazole methanol solution and heated at 70 °C for 2 hours;
[0071] The product obtained in this example is denoted as NC-4.
[0072] (2) Preparation of metal Co-modified N-doped porous carbon and investigation of cobalt concentration.
[0073] Example 5
[0074] (1) Dissolve 5 g of polyvinylpyrrolidone and 0.364 g of cobalt nitrate hexahydrate in 250 mL of deionized water to obtain a homogeneous mixed solution;
[0075] (2) Add the ZnO-ZIF-8-derived N-doped porous carbon modified carbon felt prepared in Example 3 to the above mixed solution and stir for 1 hour;
[0076] (3) Wash 3 times with deionized water and absolute ethanol, and then place in a vacuum drying oven at 60 °C for 24 hours;
[0077] (4) Place the dried modified carbon felt in an N2 atmosphere and pyrolyze at 900 °C for 2 hours with a heating rate of 5 °C / minute to obtain metal Co-modified N-doped porous carbon, denoted as Co / NC-1.
[0078] Example 6
[0079] The solution of this example is basically the same as that of Example 5, except that in step (1), 5 g of polyvinylpyrrolidone and 0.728 g of cobalt nitrate hexahydrate are dissolved in 250 mL of deionized water to obtain a homogeneous mixed solution.
[0080] The product obtained in this example is denoted as Co / NC-2.
[0081] Example 7
[0082] The solution of this example is basically the same as that of Example 5, except that in step (1), 5 g of polyvinylpyrrolidone and 1.091 g of cobalt nitrate hexahydrate are dissolved in 250 mL of deionized water to obtain a homogeneous mixed solution.
[0083] The product obtained in this example is denoted as Co / NC-3.
[0084] Example 8
[0085] The solution of this example is basically the same as that of Example 5, except that in step (1), 5 g of polyvinylpyrrolidone and 1.455 g of cobalt nitrate hexahydrate are dissolved in 250 mL of deionized water to obtain a homogeneous mixed solution.
[0086] The product obtained in this example is denoted as Co / NC-4.
[0087] Example 9
[0088] The solution of this example is basically the same as that of Example 5, except that in step (1), 5 g of polyvinylpyrrolidone and 1.819 g of cobalt nitrate hexahydrate are dissolved in 250 mL of deionized water to obtain a homogeneous mixed solution.
[0089] The product obtained in this example is denoted as Co / NC-5.
[0090] (III) Investigation of N-doped porous carbon electroadsorbents modified with different metal salts.
[0091] Comparative Example 1
[0092] (1) Dissolve 5 g of polyvinylpyrrolidone and 1.454 g of nickel nitrate hexahydrate in 250 mL of deionized water to obtain a homogeneous mixed solution;
[0093] (2) Add the ZnO-ZIF-8-derived N-doped porous carbon modified carbon felt prepared in Example 3 to the above mixed solution and stir for 1 hour;
[0094] (3) Wash with deionized water and absolute ethanol three times, and then dry in a vacuum drying oven at 60 °C for 24 hours;
[0095] (4) Place the dried modified carbon felt in an N2 atmosphere and pyrolyze at 900 °C for 2 hours with a heating rate of 5 °C / minute to obtain N-doped porous carbon modified with metal Ni, denoted as Ni / NC.
[0096] Comparative Example 2
[0097] The solution of this comparative example is basically the same as that of Comparative Example 1, except that in step (1), 5 g of polyvinylpyrrolidone and 2.02 g of ferric nitrate nonahydrate are dissolved in 250 mL of deionized water to obtain a homogeneous mixed solution.
[0098] The product obtained in this comparative example is denoted as Fe / NC.
[0099] Comparative Example 3
[0100] The solution of this comparative example is basically the same as that of Comparative Example 1, except that in step (1), 5 g of polyvinylpyrrolidone and 0.938 g of copper nitrate hexahydrate are dissolved in 250 mL of deionized water to obtain a uniformly mixed solution.
[0101] The product obtained in this comparative example is denoted as Cu / NC.
[0102] The adsorption performance and anti-interference performance of the different metal-modified N-doped porous carbon electro-adsorbents prepared in the above examples and comparative examples were tested.
[0103] Comparing Examples 1-4, as Figure 1 shown, as the concentration of the 2-methylimidazole solution increases, the relative intensities (ID:IG) of the D peak and the G peak of the ZnO-ZIF-8-derived nitrogen-doped porous carbon (NC) material gradually increase. As Figure 2 shown, the nitrate adsorption capacity of the ZnO-ZIF-8-derived nitrogen-doped porous carbon electro-adsorbent shows a trend of first increasing and then decreasing. When the concentration of the 2-methylimidazole solution is 0.14 g / mL, NC exhibits the optimal degree of defectiveness. As Figure 2 shown, the nitrate adsorption capacity of the ZIF-8-derived nitrogen-doped porous carbon electro-adsorbent reaches the maximum value. After that, as the amount of 2-methylimidazole used further increases, the introduction of excessive nitrogen defects destroys the framework structure of the carbon material, and then destroys the fast electron transport channels on the surface of the carbon material, resulting in the inactivation of some active sites. As Figure 2 shown, the nitrate adsorption capacity of the ZnO-ZIF-8-derived nitrogen-doped porous carbon electro-adsorbent begins to decrease.
[0104] Comparing Examples 5-9, for the N-doped porous carbon electro-adsorbents modified with different amounts of metal Co nanoparticles, the metal Co nanoparticles are uniformly dispersed on the surface of the material and form a stable heterostructure with NC. The X-ray diffraction (XRD) pattern is as Figure 3 shown. In the series of metal Co-modified nitrogen-doped porous carbon (Co / NC) samples, obvious Co characteristic peaks can be observed. Compared with NC, the introduction of metal Co significantly improves the removal ability of the electrode for nitrate ions. As the amount of Co salt used increases, metal Co continuously forms a heterostructure with NC and deposits on the surface of the material, constructing a fast electron transport channel and an electron-deficient Co active center, enhancing the interaction with nitrate. As Figure 3 shown, the nitrate adsorption capacity of Co / NC gradually increases; when the concentration of cobalt nitrate increases to 0.02 mol / L, its nitrate adsorption capacity reaches the maximum, indicating that at this concentration, the loading amount and distribution of metal Co reach the optimal level. When the amount of metal Co used is further increased, due to the deposition of excessive Co nanoparticles on the carbon skeleton, the pore channels are blocked. As Figure 4 shown, this causes the specific surface area of the material to decrease and the number of active sites to decrease.Figure 3 The nitrate adsorption capacity shown also decreased.
[0105] Comparing Example 8 with Comparative Examples 1-3, the N-doped porous carbon electroadsorbents modified with different metal salts showed significant differences in nitrate adsorption performance. As Figure 5 shown, when the metal Co was used to modify the N-doped porous carbon, it showed the largest nitrate adsorption capacity, followed by Ni / NC, the nitrate capacity of Fe / NC was slightly lower than that of Ni / NC, while the nitrate adsorption capacity of Cu / NC was the lowest among the N-doped porous carbons modified with the other three metal salts. This is because there is a strong electronic interaction on the Co / NC heterostructure, and the Fermi level of metal Co is significantly higher than that of NC, resulting in the transfer of electrons from Co atoms to the NC matrix, thus generating a more obvious Co atom deficient region at the Co / NC interface, thereby enhancing the electrostatic attraction with nitrate ions and improving the electroadsorption removal performance of the N-doped porous carbon electroadsorbent modified with metal Co for nitrate.
[0106] At the same time, the metal salt-modified N-doped porous carbon electroadsorbents prepared in Example 3, 8 and Comparative Examples 1-3 were used as anodes to remove nitrate in multi-solute water bodies, and their adsorption capacities for various anions are as Figure 6 shown. The Co / NC-4 prepared in Example 8 showed the highest nitrate adsorption capacity and had an obvious advantage in the adsorption difference between nitrate and the other three interfering ions. In the presence of competing ions, Co / NC-4 still maintained a high selective adsorption for nitrate. By calculating the selectivity coefficient S A / B to evaluate the selective adsorption performance of the electroadsorbent for two competing ions A and B, S A / B =(C A,i -C A,e ) / C A,i ) / (C B,i -C B,e ) / C B,i ), where C A,i and C A,e are the initial concentration and equilibrium concentration (mmol / L) of ion A respectively, C B,i (mmol / L) and C B,e (mmol / L) are the initial concentration and equilibrium concentration of ion B respectively. The selectivity of nitrate for the other three ions is as Figure 7 shown. The N-doped porous carbon electroadsorbent without metal salt modification has the worst ability to resist the interference of the three competing ions, while the N-doped porous carbon electroadsorbent modified with metal shows stronger anti-interference ability, especially to resist H2PO4 -The improvement in interference aspects is significant, and among them, Co / NC-4 has the strongest selective adsorption ability for the other three competitive ions. This is because the Co electron-deficient active sites carry a strong positive charge, which has a strong electrostatic attraction to anions, thus effectively enhancing the adsorption ability of nitrate. At the same time, due to the relatively small hydration radius and hydration energy of nitrate, its hydrated form is unstable, making it easy to dehydrate and enter the microporous structure. In addition, the construction of the mesoporous-microporous interconnected structure promotes the mass transfer of nitrate, and synergistically with the microporous confinement and sieving effects, further improves its selective adsorption ability for nitrate.
[0107] As Figure 8 shown, after ten cycles, the nitrate adsorption capacity of Co / NC-4 in Example 8 still remains above 95%. This is because the metal Co salt is uniformly dispersed on the surface of NC with the assistance of PVP, and during the high-temperature carbonization process, the deposition of metal Co nanoparticles does not damage the carbon skeleton structure of NC, nor does it cause the collapse of the skeleton and the blockage of pores, forming a stable Co / NC heterostructure, which ensures the cyclic stability of the metal Co-modified N-doped porous carbon electroadsorbent in the long-term operation mode.
[0108] The solution of the present invention significantly improves the electrostatic adsorption ability between the material surface and nitrate, and the nitrate adsorption capacity can be as high as 0.672 mmol / g.
[0109] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments still fall within the protection scope of the technical solution of the present invention.
Claims
1. A preparation method of a metal Co-modified N-doped porous carbon electro-adsorbent, characterized in that It includes the following steps: S1: Immerse the carbon felt in a zinc salt solution and react to obtain ZnO-loaded carbon felt, denoted as ZnO / CF material; S2: Immerse the ZnO / CF material in a carbon source solution and react to carbonize to obtain ZnO-ZIF-8-derived porous nitrogen-doped carbon, denoted as NC material; S3: Immerse the NC material in a mixed solution of polyvinylpyrrolidone and Co metal salt and react to carbonize to obtain a metal Co-modified N-doped porous carbon electroadsorbent, denoted as Co / NC material.
2. The preparation method of the metal Co-modified N-doped porous carbon electro-adsorbent according to claim 1, characterized in that: The zinc salt is selected from one of zinc acetate dihydrate or zinc nitrate hexahydrate.
3. The preparation method of the metal Co-modified N-doped porous carbon electroadsorbent according to claim 1, wherein: In step S1, the immersion of the carbon felt in the zinc salt solution includes: Step S1.1: Immerse the carbon felt in a methanol solution of zinc salt, let it stand, and then heat and dry it; Step S1.2: Immerse the carbon felt in a mixed aqueous solution of zinc salt and hexamethylenetetramine, stir, heat, wash, and dry it to obtain the ZnO / CF material.
4. The preparation method of the metal Co-modified N-doped porous carbon electroadsorbent according to claim 3, characterized in that: In the methanol solution of zinc salt, the molar concentration of zinc element is 0.015 - 0.025 mol / L; in the mixed aqueous solution of zinc salt and hexamethylenetetramine, the molar concentration of zinc element is 0.04 - 0.06 mol / L, and the concentration of hexamethylenetetramine is 0.005 - 0.01 g / mL.
5. The preparation method of the metal Co-modified N-doped porous carbon electroadsorbent according to claim 1, characterized in that: In step S2, immerse the ZnO / CF material in the carbon source solution, stir, heat, wash, dry, and perform high-temperature carbonization to obtain the NC material; wherein the heating temperature is 60 - 80 °C, the heating time is 1.5 - 2.5 hours; the temperature of high-temperature carbonization is 870 - 930 °C, and the carbonization time is 1.5 - 2.5 hours.
6. The preparation method of the metal Co-modified N-doped porous carbon electroadsorbent according to claim 1, characterized in that: The carbon source solution uses a 2-methylimidazole methanol solution.
7. The preparation method of the metal Co-modified N-doped porous carbon electroadsorbent according to claim 1, characterized in that: The concentration of the carbon source solution is 0.12 - 0.16 g / mL.
8. The preparation method of the metal Co-modified N-doped porous carbon electro-adsorbent according to claim 1, wherein: In step S3, immerse the NC material in a mixed aqueous solution of polyvinylpyrrolidone and Co metal salt, stir, wash, dry, and perform high-temperature carbonization treatment to obtain the Co / NC material; wherein the temperature of high-temperature carbonization is from 870 to 930 °C, and the carbonization time is 1.5 - 2.5 hours.
9. The preparation method of the metal Co-modified N-doped porous carbon electroadsorbent according to claim 1, characterized in that: In the mixed solution of polyvinylpyrrolidone and Co metal salt, the concentration of polyvinylpyrrolidone is 0.0ls - 0.025 g / mL, and the concentration of Co element in the Co metal salt is 0.018 - 0.02 mol / L.
10. A metal Co-modified N-doped porous carbon electro-adsorbent, characterized in that: It is prepared by using the method described in any one of claims 1 - 9.