A method for resource recovery and reuse of nickel in wastewater based on adsorption by organic directional porous materials

Abstract

This invention belongs to the field of water treatment and discloses a method for the resource-based reuse of nickel in wastewater based on adsorption by an organic directional porous material. The method includes: dissolving and dispersing polymer raw materials and fillers in an organic solvent to prepare a polymer suspension; pouring the suspension into a mold with one side as a heat source and the other side as a cold source, and replacing it with an ice-water mixture after complete solidification to obtain a gel-like block; mixing the block with hydroxylamine hydrochloride, inorganic salts, and distilled water to carry out a methylamine oxime reaction to obtain a directional porous organic material; placing the directional porous organic material into an adsorption column with the pore orientation aligned with the column axis to adsorb nickel-containing wastewater; and drying, pre-oxidizing, and carbonizing the adsorbed nickel organic material to obtain nickel-containing porous carbon. This nickel-containing porous carbon can be used to prepare electrode materials for supercapacitors. The polymer porous material obtained by this invention has honeycomb-like directional pores, resulting in good adsorption effect and high nickel reuse rate; it also increases the added value of nickel-containing waste adsorbents.

Description

Technical Field

[0001] This invention belongs to the field of water treatment and relates to a method for the resource-based reuse of nickel in wastewater; more particularly, it relates to a method for the resource-based reuse of nickel in wastewater based on adsorption by organic directional porous materials. Background Technology

[0002] In recent years, the problem of excessive nickel levels in aquatic environments has received increasing attention. Nickel pollutants, through groundwater circulation and soil migration, cause drinking water pollution and have high cumulative toxicity and carcinogenicity to humans. Treatment methods for nickel pollutants include coagulation sedimentation, membrane filtration, electrodeposition, and adsorption. Coagulation sedimentation easily produces toxic sludge, membrane filtration suffers from membrane fouling, and electrodeposition is complex. Adsorption methods have advantages such as safety, low pollution, ease of operation, and resource recovery potential, making them promising for treating nickel-containing wastewater. Traditional nickel adsorbents mainly include biomass, metal oxides, minerals, and carbon-based materials. Chinese patent CN102583630A discloses modified bentonite as a nickel adsorbent, achieving some success. However, traditional adsorbents lack suitable and sufficient functional groups as adsorption sites to capture heavy metals, resulting in small adsorption capacity and limited adsorption ability. Organic synthetic materials have abundant functional groups with strong heavy metal capture capabilities, theoretically possessing high bonding ability and adsorption performance for nickel. However, in adsorption research, discarded nickel-containing adsorbents can easily cause secondary pollution problems.

[0003] Currently, the main methods for treating and disposing of nickel-containing waste adsorbents are landfilling or encapsulation through stabilization / solidification, with cement solidification and asphalt solidification being common methods. However, cement and asphalt solidification bodies typically have low strength, still posing a risk of nickel leakage, and do not effectively increase the added value of the waste adsorbents. Resource recycling is not only an effective method for dealing with nickel-containing waste adsorbents but also promotes sustainable development in today's society. As a non-renewable resource, nickel is a rare earth metal resource that plays an important role in flame retardants, catalysts, refractory materials, and capacitors. Some researchers have coated nickel onto screen-printed electrodes to create nickel-containing supercapacitor electrode materials. Therefore, adsorbing and extracting nickel from nickel-containing wastewater and realizing the resource recycling of nickel-containing waste adsorbents has significant value and importance.

[0004] To address the above issues, this technology focuses on using organic synthetic materials to adsorb nickel from wastewater, then preparing nickel-containing waste adsorbents into nickel-containing supercapacitor electrode materials, and utilizing the reducing properties of the synthetic materials during carbonization to reduce high-valence nickel in the wastewater to lower-valence nickel, or even to elemental nickel, thereby achieving the resource-based reuse of nickel in wastewater. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for the resource-based reuse of nickel in wastewater based on adsorption by organic directional porous materials. This invention first synthesizes an organic material that has an adsorption response to nickel; then, it calcines the waste nickel-containing adsorbent after adsorption to prepare nickel-containing carbon-based electrode materials for supercapacitors.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for the resource-based recycling of nickel in wastewater based on adsorption by organic directional porous materials, the method comprising the following steps: S1. Dissolve and disperse polymer raw materials and fillers in an organic solvent to prepare a polymer suspension; S2. Pour the polymer suspension into a mold with a heat source on one side and a cold source on the other side. After the suspension has completely solidified, place it in an ice-water mixture for solvent replacement to obtain a (white) gel-like block. Soak and wash the block with hydrochloric acid solution. S3. Mix the gelatinous block with hydroxylamine hydrochloride, inorganic salt and distilled water and stir to carry out the amylopyrification reaction. Wash and dry the product to obtain directional porous organic material. S4. Place the oriented porous organic material into the adsorption column, with the pore orientation aligned with the axis of the adsorption column, to adsorb nickel-containing wastewater. S5. The directional porous organic material after nickel adsorption is dried, pre-oxidized and carbonized to obtain nickel-containing porous carbon.

[0007] As one implementation, the nickel-containing porous carbon is used as the active component of the supercapacitor electrode material.

[0008] As one embodiment, the nickel-containing porous carbon, acetylene black, and PTFE emulsion are mixed and stirred until homogeneous, then ethanol is added and the mixture is ground. The ground mixture is then pressed into thin sheets to obtain a supercapacitor electrode material. Preferably, the mass ratio of the porous carbon, acetylene black, and PTFE emulsion is 8.0–9.0:0.5–1.0:1.

[0009] As one embodiment, the polymer raw material is at least one selected from polystyrene, polypropylene, polylactic acid, polymethyl methacrylate, polyvinyl alcohol, polyamide, and polyacrylonitrile.

[0010] As one embodiment, the solvent is at least one selected from dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, toluene, and tetrahydrofuran.

[0011] As one implementation, the filler is nano-carbonate.

[0012] As one embodiment, the polymer concentration in the polymer suspension is 0.1 to 10.0 wt%.

[0013] In one embodiment, the mass ratio of the filler to the polymer raw material is 0.2–5.0:1. In some embodiments, the mass ratio of the filler to the polymer raw material is 0.2–0.5:1. In other embodiments, the mass ratio of the filler to the polymer raw material is 0.5–1:1, 1–2:1, or 2–5:1.

[0014] As one embodiment, the filler is a nano-carbonate with a particle size of 20–50 nm.

[0015] As one implementation, the filler is at least one of nano-calcium carbonate, nano-magnesium carbonate, and nano-basic copper carbonate.

[0016] As one implementation, the inorganic salt includes anhydrous sodium carbonate.

[0017] In one implementation, the temperature difference between the cold source and the heat source is 20–400 °C. In some implementation examples, the temperature difference between the cold source and the heat source is 250–300 °C.

[0018] As one implementation, the cold source temperature is -20 to -196 ℃, and the heat source temperature is 0 to 200 ℃.

[0019] As one embodiment, the reaction temperature for the amine oxime is 50–80 °C, and the mass ratio of the bulk precursor (gelatinous bulk) to hydroxylamine hydrochloride and inorganic salt (such as anhydrous sodium carbonate) is 0.1–5.0:6.0–8.0:3.8–6.8. The mass ratio of the gelatinous bulk to deionized water is 0.1–5.0:100.

[0020] As one implementation scheme, when studying the adsorption of nickel-containing wastewater, the adsorption column flow rate was 0.1–10.0 mL / min, and the influent concentration was 0.1–50.0 mg / L. The column height was 100–150 mm.

[0021] As one implementation, the pre-oxidation temperature is 200–320 °C, and the time is 1.0–6.0 h.

[0022] As one implementation, the carbonization temperature is 400–1500 °C, and the time is 2.0–12.0 h.

[0023] This invention also provides a method for preparing the aforementioned organic oriented porous material, the method comprising the following steps: S1. Dissolve and disperse polymer raw materials and fillers in an organic solvent to prepare a polymer suspension; S2. Pour the polymer suspension into a mold with a heat source on one side and a cold source on the other side. After the suspension has completely solidified, place it in an ice-water mixture for solvent replacement to obtain a gel-like block. Soak and wash the block with hydrochloric acid solution. S3. Mix the gelatinous block with hydroxylamine hydrochloride, inorganic salt and distilled water, and carry out a methylamine oxime reaction. Wash and dry the product to obtain a directional porous organic material.

[0024] The organic oriented porous material prepared by the aforementioned method is also within the scope of protection of this invention when used as an adsorbent for nickel-containing wastewater or in the preparation of nickel-containing porous carbon after adsorbing nickel.

[0025] As one implementation, the directional porous organic material after nickel adsorption is dried, pre-oxidized, and carbonized to obtain nickel-containing porous carbon; the nickel-containing porous carbon is used to prepare supercapacitor electrode materials.

[0026] Compared with the prior art, the present invention has the following beneficial effects: 1) The adsorbent raw materials are traditional chemical raw materials with abundant sources; the porous adsorbent material has honeycomb-shaped directional pores, resulting in good adsorption effect; the operation is simple and the nickel recycling rate is high; it increases the added value of nickel-containing waste adsorbents and realizes the resource recycling of nickel.

[0027] 2) This invention uses a specific oriented porous organic material (polyacrylonitrile) as a precursor to adsorb nickel. The synthesized oriented pores can significantly improve the adsorption efficiency of the adsorption column and reduce water penetration resistance. Even after carbonization, the oriented pores remain. Therefore, when the specific oriented porous organic material itself acts as a carbonization precursor, it exhibits strong reducing properties during carbonization, reducing nickel oxide to elemental nickel, which is more suitable as an electrode material. This is beneficial for improving the directional diffusion of the electrolyte and increasing the electrode capacitance. Attached Figure Description

[0028] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the preparation of oriented organic materials in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the adsorbent in Example 1 of the present invention; Figure 3 This is a schematic diagram of the adsorption process in Example 1 of the present invention; Figure 4 This is a synchrotron radiation wavelet transform diagram of Embodiment 1 of the present invention; Figure 5 This is a cyclic voltammetry curve of the supercapacitor electrode material in Embodiment 1 of the present invention. Detailed Implementation

[0029] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0030] Example 1 This embodiment relates to a method for the resource-based reuse of nickel in wastewater based on adsorption by organic oriented porous materials, including: (1) Polyacrylonitrile and nano-calcium carbonate filler are dissolved and dispersed in dimethyl sulfoxide to prepare a polymer suspension, wherein the polymer concentration is 5% and the mass ratio of PAN to nano-calcium carbonate is 2.0; (2) The polymer suspension was poured into a square mold. The cold source temperature was -196℃ and the heat source temperature was 70℃. After the suspension was completely solidified, it was placed in an ice-water mixture for solvent replacement. After 2 hours, a white gel-like block was obtained, as shown in the schematic diagram. Figure 1 The object was soaked and washed with hydrochloric acid solution. (3) The block was mixed with hydroxylamine hydrochloride, anhydrous sodium carbonate (mass ratio 1.0:8.0:5.8) and distilled water, stirred, and the product of the amine oxime reaction was washed and dried to obtain oriented porous polyacrylonitrile ( Figure 2 ); (4) Porous polyacrylonitrile was placed into an adsorption column to conduct an adsorption experiment on nickel-containing wastewater. Figure 3 The adsorption column has a height of 120 mm, a flow rate of 1.25 mL / min, an influent concentration of 40.0 mg / L, and an adsorption capacity of 450.0 mg / g. (5) The waste adsorbent after nickel adsorption was dried, pre-oxidized (280℃, 5 h) and carbonized (800℃, 2 h) to obtain nickel-containing porous carbon. The synchrotron radiation wavelet transform diagram is shown below. Figure 4 ; (6) Mix and stir nickel-containing porous carbon, acetylene black and PTFE emulsion (mass ratio of 8:1:1), then add ethanol and grind; prepare the mixture as a supercapacitor electrode material.

[0031] The specific capacitance was tested using a three-electrode system, with a saturated calomel electrode as the reference electrode, a platinum electrode as the auxiliary electrode, and the prepared electrode (2.0 mg) as the working electrode. A 6 mol / L potassium hydroxide solution was used as the electrolyte. Cyclic voltammetry was performed in the potential range of -1.0 to 0 V, with different scan rates of 5, 10, 50, and 100 mV / s. Figure 5The results showed that the specific capacitance of the prepared electrode material was 362.4 F / g, and the resource utilization rate of nickel was 50.1%, as determined by the weighing method.

[0032] Example 2 This embodiment relates to a method for the resource-based reuse of nickel in wastewater based on adsorption by organic oriented porous materials, including: (1) Polyacrylonitrile and nano-calcium carbonate filler are dissolved and dispersed in dimethyl sulfoxide to prepare a polymer suspension, wherein the polymer concentration is 5% and the mass ratio of PAN to nano-calcium carbonate is 2.0; (2) The polymer suspension was poured into a square mold. The cold source temperature was -196℃ and the heat source temperature was 70℃. After the suspension was completely solidified, it was placed in an ice-water mixture for solvent replacement. After 2 hours, a white gel-like block was obtained. The block was soaked and washed with hydrochloric acid solution. (3) Mix the block with hydroxylamine hydrochloride, anhydrous sodium carbonate (mass ratio of 1.0:8.0:5.8) and distilled water, stir, wash and dry the product of the amylopyridine reaction to obtain directional porous polyacrylonitrile; (4) Porous polyacrylonitrile was placed into an adsorption column to conduct an adsorption experiment on nickel-containing wastewater. The column height was 120 mm, the flow rate was 1.25 mL / min, the influent concentration was 30.0 mg / L, and the adsorption capacity was 443.0 mg / g. (5) The waste adsorbent after adsorbing nickel is dried, pre-oxidized (280℃, 5 h) and carbonized (800℃, 2 h) to obtain nickel-containing porous carbon; (6) Mix and stir nickel-containing porous carbon, acetylene black and PTFE emulsion (mass ratio of 8:1:1), then add ethanol and grind; press the ground mixture to obtain supercapacitor electrode material.

[0033] The specific capacitance was tested using a three-electrode system, with a saturated calomel electrode as the reference electrode, a platinum electrode as the auxiliary electrode, and the prepared electrode as the working electrode. A 6 mol / L potassium hydroxide solution was used as the electrolyte. Cyclic voltammetry was performed in the potential range of -1.0 to 0 V, with different scan rates of 5, 10, 50, and 100 mV / s. The results showed that the specific capacitance of the prepared electrode material was 335.0 F / g, determined by weighing, and the resource recovery rate of nickel was 50.7%.

[0034] Example 3 This embodiment relates to a method for the resource-based reuse of nickel in wastewater based on adsorption by organic oriented porous materials, including: (1) Polylactic acid and nano-calcium carbonate filler are dissolved and dispersed in dimethyl sulfoxide to prepare a polymer suspension, wherein the polymer concentration is 5% and the mass ratio of polylactic acid to nano-calcium carbonate is 2.0; (2) The polymer suspension was poured into a square mold. The cold source temperature was -196℃ and the heat source temperature was 70℃. After the suspension was completely solidified, it was placed in an ice-water mixture for solvent replacement. After 2 hours, a white gel-like block was obtained. The block was soaked and washed with hydrochloric acid solution. (3) Mix the block with hydroxylamine hydrochloride, anhydrous sodium carbonate (mass ratio of 1.0:8.0:5.8) and distilled water, stir, wash and dry the product of the amylopyridine reaction to obtain directional porous polylactic acid; (4) Porous polylactic acid was placed into an adsorption column to conduct an adsorption experiment on nickel-containing wastewater. The column height was 120 mm, the flow rate was 1.25 mL / min, the influent concentration was 40.0 mg / L, and the adsorption capacity was 449.0 mg / g. (5) The waste adsorbent after adsorbing nickel is dried, pre-oxidized (200℃, 5 h) and carbonized (400℃, 2 h) to obtain nickel-containing porous carbon; (6) Mix and stir nickel-containing porous carbon, acetylene black and PTFE emulsion (mass ratio of 8:1:1), then add ethanol and grind; press the ground mixture to obtain supercapacitor electrode material.

[0035] The specific capacitance was tested using a three-electrode system, with a saturated calomel electrode as the reference electrode, a platinum electrode as the auxiliary electrode, and the prepared electrode as the working electrode. A 6 mol / L potassium hydroxide solution was used as the electrolyte. Cyclic voltammetry was performed in the potential range of -1.0 to 0 V, with different scan rates of 5, 10, 50, and 100 mV / s. The results showed that the specific capacitance of the prepared electrode material was 374 F / g, and the resource recovery rate of nickel was 52.2%.

[0036] Example 4 This embodiment relates to a method for the resource-based reuse of nickel in wastewater based on adsorption by organic oriented porous materials, including: (1) Polystyrene and nano-calcium carbonate filler are dissolved and dispersed in dimethyl sulfoxide to prepare a polymer suspension, wherein the polymer concentration is 5% and the mass ratio of polystyrene to nano-calcium carbonate is 2.0; (2) The polymer suspension was poured into a square mold. The cold source temperature was -196℃ and the heat source temperature was 70℃. After the suspension was completely solidified, it was placed in an ice-water mixture for solvent replacement. After 2 hours, a white gel-like block was obtained. The block was soaked and washed with hydrochloric acid solution. (3) Mix the block with hydroxylamine hydrochloride, anhydrous sodium carbonate (mass ratio of 1.0:8.0:5.8) and distilled water, stir, wash and dry the product of the amylopyridine reaction to obtain oriented porous polystyrene; (4) Porous polystyrene was placed into an adsorption column to conduct an adsorption experiment on nickel-containing wastewater. The column height was 120 mm, the flow rate was 1.25 mL / min, the influent concentration was 40.0 mg / L, and the adsorption capacity was 475.0 mg / g. (5) The waste adsorbent after adsorbing nickel is dried, pre-oxidized (200℃, 5 h) and carbonized (600℃, 2 h) to obtain nickel-containing porous carbon; (6) Mix and stir nickel-containing porous carbon, acetylene black and PTFE emulsion (mass ratio of 8:1:1), then add ethanol and grind; press the ground mixture to obtain supercapacitor electrode material.

[0037] The specific capacitance was tested using a three-electrode system, with a saturated calomel electrode as the reference electrode, a platinum electrode as the auxiliary electrode, and the prepared electrode as the working electrode. A 6 mol / L potassium hydroxide solution was used as the electrolyte. Cyclic voltammetry was performed in the potential range of -1.0 to 0 V, with different scan rates of 5, 10, 50, and 100 mV / s. The results showed that the specific capacitance of the prepared electrode material was 379.0 F / g, and the resource recovery rate of nickel was 52.5%.

[0038] Comparative Example 1 The polymer suspension from Example 1 was rapidly sprayed into a container filled with liquid nitrogen using a mechanical spraying method. At 196.0℃, the quenching time was 1 min. During this process, the mist-like droplets solidified to form gel-like microspheres, which were then immersed in an ice / water mixture for 24 h. That is, step (2) was adjusted, and other operating methods were the same as in Example 1. The adsorption capacity of nickel in nickel-containing wastewater was measured to be 220.0 mg / g.

[0039] The specific capacitance was tested using a three-electrode system, with a saturated calomel electrode as the reference electrode, a platinum electrode as the auxiliary electrode, and the prepared electrode as the working electrode. A 6 mol / L potassium hydroxide solution was used as the electrolyte. Cyclic voltammetry was performed in the potential range of -1.0 to 0 V, with different scan rates of 5, 10, 50, and 100 mV / s. The results showed that the specific capacitance of the prepared electrode material was 98.3 F / g, and the resource recovery rate of nickel was 10.3%, which is significantly lower than that of Example 1.

[0040] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for the resource-based reuse of nickel in wastewater based on adsorption by organic directional porous materials, characterized in that, The method includes the following steps: S1. Dissolve and disperse polymer raw materials and fillers in an organic solvent to prepare a polymer suspension; S2. Pour the polymer suspension into a mold with a heat source on one side and a cold source on the other side. After the suspension has completely solidified, place it in an ice-water mixture for solvent replacement to obtain a gel-like block. Soak and wash the block with hydrochloric acid solution. S3. Mix the gelatinous block with hydroxylamine hydrochloride, inorganic salt and distilled water and stir to carry out the amylopyrification reaction. Wash and dry the product to obtain oriented porous organic material. S4. Place the oriented porous organic material into the adsorption column, with the pore orientation aligned with the axis of the adsorption column, to adsorb nickel-containing wastewater. S5. The directional porous organic material after nickel adsorption is dried, pre-oxidized and carbonized to obtain nickel-containing porous carbon.

2. The method for resource recovery and reuse of nickel in wastewater based on adsorption by organic directional porous materials according to claim 1, characterized in that, The nickel-containing porous carbon is used as the active component of the supercapacitor electrode material.

3. The method for resource recovery and reuse of nickel in wastewater based on adsorption by organic directional porous materials according to claim 2, characterized in that, The nickel-containing porous carbon, acetylene black, and PTFE emulsion are mixed and stirred until homogeneous, and then ethanol is added for grinding. The ground mixture is pressed into thin sheets to obtain the supercapacitor electrode material.

4. The method for resource recovery and reuse of nickel in wastewater based on adsorption by organic directional porous materials according to claim 1, characterized in that, The polymer raw material is at least one of polystyrene, polypropylene, polylactic acid, polymethyl methacrylate, polyvinyl alcohol, polyamide, and polyacrylonitrile; And / or, the filler is nano-carbonate; And / or, the solvent is at least one selected from dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, toluene, and tetrahydrofuran.

5. The method for resource recovery and reuse of nickel in wastewater based on adsorption by organic directional porous materials according to claim 1 or 4, characterized in that, The polymer concentration in the polymer suspension is 0.1–10.0 wt%; And / or, the mass ratio of the filler to the polymer raw material is 0.2 to 5.0:1; And / or, the filler is a nano-carbonate with a particle size of 20–50 nm; And / or, the filler is at least one of nano-calcium carbonate, nano-magnesium carbonate, and nano-basic copper carbonate; And / or, the inorganic salt includes anhydrous sodium carbonate.

6. The method for resource recovery and reuse of nickel in wastewater based on adsorption by organic directional porous materials according to claim 1, characterized in that, The temperature of the cold source is -20 to -196 ℃, and the temperature of the heat source is 0 to 200 ℃; And / or, the reaction temperature for the amylopyroxylation is 50–80 °C, and the mass ratio of the gelatinous mass to hydroxylamine hydrochloride and inorganic salt is 0.1–5.0: 6.0–8.0: 3.8–6.8; And / or, the pre-oxidation temperature is 200–320 °C, and the time is 1.0–6.0 h; And / or, the carbonization temperature is 400–1500 °C, and the time is 2.0–12.0 h.

7. The method for resource recovery and reuse of nickel in wastewater based on adsorption by organic directional porous materials according to claim 1, characterized in that, In step S4, during the adsorption of nickel-containing wastewater, the adsorption column flow rate is 0.1–10.0 mL / min, and the influent concentration is 0.1–50.0 mg / L.

8. A method for preparing an organic directional porous material, characterized in that, The method includes the following steps: S1. Dissolve and disperse polymer raw materials and fillers in an organic solvent to prepare a polymer suspension; S2. Pour the polymer suspension into a mold with a heat source on one side and a cold source on the other side. After the suspension has completely solidified, place it in an ice-water mixture for solvent replacement to obtain a gel-like block. Soak and wash the block with hydrochloric acid solution. S3. Mix the gelatinous block with hydroxylamine hydrochloride, inorganic salt and distilled water, and carry out a methylamine oxime reaction. Wash and dry the product to obtain a directional porous organic material.

9. The application of an organic oriented porous material prepared by the method described in claim 8 as an adsorbent for nickel-containing wastewater, or in the preparation of nickel-containing porous carbon after adsorbing nickel.

10. The application according to claim 9, characterized in that, The directional porous organic material after nickel adsorption is dried, pre-oxidized and carbonized to obtain nickel-containing porous carbon; the nickel-containing porous carbon is used to prepare supercapacitor electrode materials.

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