CN111128566A - Method for removing metal ions in electrode material and super capacitor - Google Patents
Method for removing metal ions in electrode material and super capacitor Download PDFInfo
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- CN111128566A CN111128566A CN201911318218.0A CN201911318218A CN111128566A CN 111128566 A CN111128566 A CN 111128566A CN 201911318218 A CN201911318218 A CN 201911318218A CN 111128566 A CN111128566 A CN 111128566A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/354—After-treatment
- C01B32/378—Purification
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/22—Electrodes
- H01G11/30—Electrodes characterised by their material
- H01G11/32—Carbon-based
- H01G11/34—Carbon-based characterised by carbonisation or activation of carbon
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/13—Energy storage using capacitors
Abstract
The invention relates to a method for removing metal ions in an electrode material and a super capacitor, belongs to the technical field of new energy materials, and solves the problems that the existing process for removing the metal ions needs to repeatedly treat the material, a large amount of acid-containing wastewater is generated, and great environmental-protection treatment pressure is caused, and the sum of the concentrations of the metal ions in the electrode material treated by the existing process is too high to meet the technical requirement that the sum of the concentrations of the metal ions in a super capacitor electrode carbon material is less than 200 ppm. The method for removing the metal ions in the electrode material comprises the following steps: step 1: preparing water carbon slurry; step 2: carrying out surface oxidation treatment on the raw material carbon in the water carbon slurry by adopting an ozone contact oxidation method; and step 3: and heating the water carbon slurry subjected to ozone contact treatment. The invention realizes the removal of the sum of the contents of various metal ions to the level of less than 60ppm by adopting the modes of ozone contact oxidation and heat treatment.
Description
Technical Field
The invention relates to the technical field of new energy materials, in particular to a method for removing metal ions in an electrode material and a super capacitor.
Background
At present, with the rapid increase of energy consumption, various environmental and sustainable development problems are increasingly highlighted. Energy storage and energy management are key technologies if these problems are to be solved. An ultracapacitor, the double layer capacitor (EDLC), is an electrochemical energy storage device that stores energy far in excess of conventional electrolytic capacitors. Supercapacitors can be viewed as symmetrical carbon-carbon electrochemical capacitors, the unique performance of which is based on nanoscale capacitors formed on the basis of polarized electrode materials and ionic layers adsorbed on their surfaces. The super capacitor is capable of energy harvesting in a very short time and then releasing the energy as needed. In market application, the super capacitor is mainly applied to automobiles and static systems, can save 10-40% of energy, and plays an important role in stabilizing current when intermittent renewable energy is connected to a hybrid energy system.
Although supercapacitors have been put into commercial use, there is a need for improvements, and new material developments in accordance with the actual demand. The industrial super capacitor mainly adopts a nano-pore carbon material as an electrode material, and has the advantages of rich raw material types, low cost, chemical inertness, good conductivity, diversified structure and surface functions and the like. Therefore, research into electrode carbon materials is also ongoing. There are different types of carbon that can be used as the active material of the supercapacitor electrode, including: powdered activated carbon, activated carbon fiber, carbon nanotube and other nano carbon, carbon aerogel, etc. There are also many new laboratory scale carbon materials that have been tried as electrode materials, but in terms of industrial applications, cost and performance are fundamental factors in the success of carbon materials. Currently commercially available activated carbon materials include: wood-based activated carbon, coconut shell activated carbon, coal-based activated carbon, and the like, which are widely available and inexpensive, but these carbons are not produced for energy storage and have many problems: low purity, high surface group content, and non-uniform particle size distribution, which all contribute to very short device lifetimes. There is a need to develop or improve new carbon materials specifically for supercapacitors on the basis of existing activated carbon materials.
Natural activated carbon without any special treatment is not directly applicable to a supercapacitor, and contains impurities, particularly metal ions. The presence of metal ions may cause other electrochemical phenomena, such as short circuit or self-discharge, on the one hand, and may cause the device to bulge due to electrolysis of the electrolyte, thereby shortening the life of the battery or causing serious safety hazards. Therefore, removing trace metal ions is a very important process in the production of all super capacitor carbon materials. Currently, the industrial treatment adopts oxidation and acid washing methods, which uses large amounts of oxidants such as hydrogen peroxide and nitric acid, as well as inorganic acids such as sulfuric acid and hydrochloric acid (EP1176617(2002) for Honda Motor and Kuraray co., WO2004011371(2004) for Kuraray Chemical and Honda, US20080201925(2008) for Maxwell Technologies, WO2008106533(2008) for Maxwell Technologies), so that the materials must be repeatedly treated to achieve a low metal ion content, thereby generating a large amount of acid-containing wastewater and causing great environmental treatment pressure.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a method for removing metal ions from an electrode material and a super capacitor, which can solve at least one of the following technical problems: (1) the existing process for removing metal ions needs to repeatedly treat materials, generates a large amount of acid-containing wastewater, and causes great environmental protection treatment pressure; (2) the concentration sum of metal ions in the electrode material treated by the prior art is too high, and the technical requirement that the concentration sum of the metal ions in the electrode carbon material of the super capacitor is less than 200ppm cannot be met.
The purpose of the invention is mainly realized by the following technical scheme:
in one aspect, the present invention provides a method for removing metal ions from an electrode material, comprising the following steps:
step 1: preparing water carbon slurry;
step 2: carrying out surface oxidation treatment on the raw material carbon in the water carbon slurry by adopting an ozone contact oxidation method;
and step 3: and heating the water carbon slurry subjected to ozone contact treatment.
On the basis of the scheme, the invention is further improved as follows:
further, in the step 1, the solid content in the water-carbon slurry is 5 wt% to 30 wt%.
Further, step 3 is followed by the steps of:
and 4, step 4: filtering, and reconfiguring the wet sample and deionized water to obtain secondary water-carbon slurry;
and 5: carrying out surface oxidation treatment on the raw material carbon in the secondary water carbon slurry by adopting an ozone contact oxidation method;
step 6: and heating the secondary water-carbon slurry subjected to ozone contact treatment.
Further, step 6 is followed by step 7: and (3) filter-pressing and drying the carbon material, performing high-temperature heat treatment in a nitrogen atmosphere, wherein the temperature of the high-temperature heat treatment is 650-850 ℃, the treatment time is 30-120 minutes at the corresponding temperature, and then gradually cooling the sample to room temperature in the nitrogen.
Further, step 6 is followed by step 8: the carbon material is stored in a carbon dioxide gas isolated storage mode.
Further, in step 1, the charcoal used for preparing the water charcoal slurry is the charcoal raw material subjected to alkali activation treatment.
Further, before the step 1, the method comprises the step of neutralizing the carbon raw material subjected to the alkali activation treatment until the surface of the carbon raw material is neutral.
Further, in the step 2, the ozone content in the water carbon slurry is 0.5-2.0 mg/L.
Further, in the step 3, the temperature of the heating treatment is 70-95 ℃, and the time of the heating treatment is 30-90 minutes.
Further, in step 3, stirring is performed during the heat treatment.
On the other hand, the invention also provides a super capacitor, wherein the electrode material of the super capacitor is activated carbon, and the method is adopted to remove trace metal ions in the activated carbon.
Further, the sum of the total concentration of metal ions in the activated carbon is less than 60 ppm.
The invention can realize at least one of the following beneficial effects:
(1) different from the existing mode of removing metal ions by adopting an oxidation and acid washing method, the method adopts an ozone contact oxidation method to carry out surface oxidation treatment on the carbon raw material, simultaneously converts part of transition metal elements into high-valence oxygen-containing negative ions, eliminates the electrostatic action between the functional groups on the surface of the raw material and the metal ions, and ensures that trace metal ions can be directly eluted and removed. The method for removing the metal ions can control the sum of the contents of various metal ions within a very low range (less than 60ppm) without repeatedly treating the material, and does not need repeated acid washing, so that a large amount of acid-containing wastewater is not generated, and the method is more energy-saving and environment-friendly. The existing method adopting oxidation and acid washing can only control the sum of the total concentration of metal ions to be 150-200 ppm, and even to be 300-400 ppm even though the method adopts repeated acid washing, which is far higher than the sum of the total concentration of the metal ions (less than 60ppm) in the electrode material obtained by the removal method of the invention.
(2) The invention can ensure that the solid amount treated in unit time is not too small, namely the process efficiency is not too low, and the system blockage caused by local sedimentation formed by too high solid content can be avoided by controlling the specific solid content (5-30 wt%) in the water-carbon slurry.
(3) The carbon raw material is subjected to alkali activation treatment, so that the pore forming of the carbon raw material is realized, and the high-capacity supercapacitor electrode carbon material can be obtained.
(4) The carbon raw material is neutralized, so that the surface of the carbon raw material is neutral, the interaction between the surface of the material and ozone is favorably realized, and the content of metal ions is further reduced.
(5) By controlling the ozone content in the water carbon slurry to be 0.5-2.0 mg/L, the surface of the raw material carbon can be completely oxidized, and environmental pollution caused by excessive ozone can be avoided.
(6) By heating the water carbon slurry subjected to ozone contact treatment, residual metal ions on the surface of the carbon material can be dissolved out, so that the content of trace metal ions in the activated carbon material is further reduced.
(7) By selecting the specific heating temperature (70-95 ℃) and the specific heating time (30-90 minutes), the minimum water consumption and operation workload can be ensured, so that the metal ion elution achieves a good effect (less than 60 ppm).
(8) By stirring in the heating treatment process, the water-carbon slurry can be ensured not to be settled and the heat transfer is uniform.
(9) The carbon material is subjected to secondary ozone contact oxidation and heating treatment, so that the content of metal ions in the carbon material is further reduced to less than 60ppm, and the requirement that the sum of the contents of trace metal ions in the carbon material of the super capacitor is less than 200ppm is met.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a sectional continuous contact reactor used in the ozone oxidation process of the embodiment of the present invention.
Detailed Description
The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention and not to limit its scope.
The invention discloses a method for removing trace metal ions in super-capacitor activated carbon, which comprises the following steps:
step 1: preparing water carbon slurry;
step 2: carrying out surface oxidation treatment on the raw material carbon in the water carbon slurry by adopting an ozone contact oxidation method;
and step 3: heating the water-carbon slurry subjected to ozone contact treatment;
and 4, step 4: filtering, reconfiguring the wet sample and deionized water to obtain secondary water-carbon slurry, and repeating ozone oxidation and heating treatment once;
and 5: filtering, drying and carrying out high-temperature heat treatment on the obtained carbon sample.
Compared with the prior art, the method for removing trace metal ions from the supercapacitor activated carbon provided by the embodiment adopts an ozone contact oxidation method to perform surface oxidation treatment on the raw material carbon, and simultaneously converts part of transition metal elements into high-valence oxygen-containing negative ions, so that the electrostatic interaction between the functional groups on the surface of the raw material and the metal ions is eliminated, and the trace metal ions can be directly eluted and removed. The total concentration sum of the metal ions can be lower than 200ppm by using the method, and the technical requirement of the electrode carbon material of the super capacitor is met.
The raw material carbon used in the invention comprises wood activated carbon, coconut shell activated carbon or coal activated carbon.
It should be noted that the solids content of the water char slurry cannot be too high or too low. Specifically, in the method for removing trace metal ions in the supercapacitor active carbon, the solid content in the water-carbon slurry is controlled to be 5-30 wt%.
This solids content range is used for water carbon slurries primarily for the following reasons: when the solid content is less than 5 wt%, the amount of solids treated per unit time is too small, and the process efficiency is low; when the solid content is higher than 30 wt%, the fluidity of the water-carbon slurry is affected by the excessively high solid content, and the system is easily blocked due to local sedimentation, so that the excessively high solid content of the water-carbon slurry needs to be avoided. The invention controls the solid content in the water-carbon slurry to be 5 wt% -30 wt%, which can ensure certain process efficiency and can not cause system blockage.
It is noted that the charcoal in step 1 is an activated charcoal raw material subjected to alkali activation treatment. The alkali activation treatment is carried out to carry out pore-forming on the carbon raw material, so that the high-capacity super-capacitor electrode carbon material can be obtained. Illustratively, the base used for the activation treatment is sodium hydroxide or potassium hydroxide.
Considering that the carbon raw material is alkaline after being subjected to alkali activation treatment, if the surface of the carbon material is alkaline (the pH value is more than 7), the interaction between the surface of the material and ozone is inhibited, and if the surface of the carbon material is acidic (the pH value is less than 7), the ozone decomposition is accelerated, which is also not beneficial to the oxidation treatment of the surface of the material. Therefore, before preparing the water carbon slurry, the carbon raw material is subjected to neutralization treatment until the pH value of the surface of the carbon raw material is 7.0. Specifically, dilute nitric acid (concentration less than 6mol/L) is used for neutralization until the surface pH value is 7.0.
In step 2, the ozone oxidation process was carried out in a staged continuous contact reactor as shown in FIG. 1, and the ozone was supplied from a mixed gas containing 2.0 wt% ozone directly produced from an ozone generator through air. The ozone-containing airflow is fully contacted with the water carbon slurry in the segmented contact reactor, the range of the volume ratio of the ozone amount to the water carbon slurry is 0.5-2.0 mg/L, and the contact time of the ozone/air airflow and the water carbon slurry is 5-20 minutes.
It should be noted that when the ratio of the amount of ozone to the volume of the water-carbon slurry is less than 0.5mg/L, on one hand, the oxidation of the surface of the raw material carbon is incomplete, on the other hand, the transition metal element cannot be converted into a high-valence oxygen-containing negative ion, and the electrostatic interaction between the functional group on the surface of the raw material and the metal ion cannot be eliminated, so that the trace amount of metal ions cannot be directly eluted and removed.
In addition, because ozone is a pollutant, the usage amount of ozone is enough to meet the use requirement, and the usage amount is not too high. Experimental research shows that the use requirement can be met when the volume ratio of the ozone amount to the water-carbon slurry is 2.0 mg/L.
Considering that residual metal ions may still exist on the surface of the water carbon slurry after the ozone oxidation treatment, in order to further reduce the content of trace metal ions in the carbon material, the preparation method of the invention also carries out heating treatment after the ozone oxidation treatment on the water carbon slurry. The heating treatment is carried out to dissolve out the residual metal ions on the surface of the carbon material, thereby further reducing the content of trace metal ions in the activated carbon material.
Specifically, the heating treatment is carried out in a reaction kettle with a polytetrafluoroethylene lining, and the temperature range adopted in the process is 70-95 ℃.
It should be noted that, in order to ensure that the water-carbon slurry does not settle and the heat transfer is uniform, mechanical stirring is adopted in the heating treatment process. Illustratively, the stirring speed is 3-300 rpm, and the heating time is 30-90 minutes. The heating elution condition can ensure that the least water consumption and operation workload are used, so that the metal ion elution achieves good effect.
Considering that the removal effect of the metal ions is limited after the primary ozone contact oxidation and heating treatment, in this embodiment, after the primary ozone contact oxidation and heating treatment, the secondary water-carbon slurry is prepared, and the ozone contact oxidation and heating treatment is repeated once, so that the content of the metal ions in the activated carbon material is further reduced to less than 60ppm, and the requirement that the sum of the contents of trace metal ions in the supercapacitor carbon material is less than 200ppm is far satisfied.
Specifically, after most of moisture in the heated charcoal slurry is removed through filter pressing, the charcoal slurry is directly reconfigured with deionized water in a wet sample without further drying. The secondary water carbon slurry is subjected to ozone contact oxidation and heating treatment once.
In the whole treatment process, the used added molecule is ozone which can be automatically decomposed in the treatment process. Considering that there is a small amount of unreacted ozone in the treatment process, and if the ozone is directly discharged, air pollution is caused, therefore, the present embodiment is provided with a tail gas recovery treatment device for absorbing and treating the small amount of unreacted ozone in the tail gas section, and no pollutant and waste are generated in the whole process. In addition, in the method for removing trace metal ions from the supercapacitor activated carbon, water in the water-carbon slurry can elute trace metal ions, does not contain waste acid, alkali or organic matters, and can be directly discharged or recycled to be applied to corresponding industrial links after being treated.
Compared with acid-containing wastewater which is discharged by tens of times or even hundreds of times in the commonly adopted acid cleaning process, the method disclosed by the invention basically has no problem of wastewater discharge pollution, simultaneously greatly reduces the consumption of elution water and the elution operation times, and is a method for efficiently and environmentally removing trace metal ions in super activated carbon.
Considering that if the oxygen content of the surface of the material is too high, on one hand, the reversible pseudocapacitance capacity of the super capacitor device is increased, and the impedance of the material is increased; on the other hand, the oxygen-containing functional group on the surface can cause gas release in the charging and discharging process, and the safety performance and the service life of the device are seriously reduced. Therefore, in the method of the present invention, after the carbon sample subjected to the liquid phase oxidation and elution process is dried, a high temperature heat treatment is further performed to remove the aerobic functional groups on the surface of the carbon material by decomposition, thereby further reducing the surface oxygen content of the carbon material.
Specifically, the high-temperature heat treatment is carried out in nitrogen, the temperature adopted for the treatment is 650-850 ℃, the treatment time is 30-120 minutes at the corresponding temperature, and then the sample is gradually cooled to the room temperature in the nitrogen. Under the conditions of the treatment temperature and the treatment time, the oxygen-containing functional groups can be completely thermally decomposed into carbon dioxide or carbon monoxide to be removed from the surface of the material.
Considering that although the surface of the particles has been cooled in nitrogen, it is possible that the temperature inside the particles is high, if the particles are exposed to air at this time, oxygen and moisture in the air come into contact with the particles to generate a new oxygen-containing surface. Therefore, in the preparation method of the embodiment, the sample adopts a carbon dioxide gas isolated storage mode, which can effectively prevent the temperature inside the particles from being too high and not being completely cooled, and avoid the contact with oxygen and moisture in the air to generate a new oxygen-containing surface.
In order to judge whether the content of various metal ions in the solid product prepared by the method meets the technical requirement of a supercapacitor electrode carbon material, the content of various metal ions in the solid product obtained by final treatment is measured by inductively coupled plasma atomic emission spectrometry (ICP-AES).
In particular, the solid sample is subjected to digestion prior to testing, the digestion being carried out according to standard procedures US EPA 3050B.
Example 1
The wood activated carbon activated by potassium hydroxide or sodium hydroxide is neutralized to a surface pH value of 7.0 by dilute nitric acid (concentration), and then is prepared into water carbon slurry with a solid content of 20 wt% with deionized water. The ratio of the ozone amount used in the ozone oxidation process to the volume of the water carbon slurry is 1.2mg/L, and the contact time of the ozone/air airflow and the water carbon slurry is 20 min. The temperature range of the heating treatment of the oxidized water-carbon slurry is 85 ℃, and the treatment time is 45 min. Most of water is removed by filter pressing, further drying is not needed, and the wet sample and deionized water are directly used for preparing the water-carbon slurry again. The ozone oxidation and the heat treatment were repeated once. The treated carbon material was subjected to pressure filtration, dried, and then heat-treated at 650 ℃ for 120 minutes in a nitrogen atmosphere. And determining the content of various metal ions in the finally processed solid product by adopting inductively coupled plasma atomic emission spectrometry (ICP-AES), wherein the solid sample needs to be subjected to digestion treatment before testing, and the digestion treatment is operated according to a standard method US EPA 3050B. The test results of the samples are shown in table 1.
TABLE 1 test results for the samples
Note: ND means that this method was not detected.
Example 2
The coconut shell activated carbon activated by potassium hydroxide or sodium hydroxide is neutralized to the surface pH value of 7.0 by dilute nitric acid (concentration), and then is prepared into water carbon slurry with the solid content of 20 wt% by deionized water. The ratio of the ozone amount used in the ozone oxidation process to the volume of the water carbon slurry is 1.2mg/L, and the contact time of the ozone/air airflow and the water carbon slurry is 20 min. The temperature range of the heating treatment of the oxidized water-carbon slurry is 85 ℃, and the treatment time is 45 min. Most of water is removed by filter pressing, further drying is not needed, and the wet sample and deionized water are directly used for preparing the water-carbon slurry again. The ozone oxidation and the heat treatment were repeated once. The treated carbon material was subjected to filter pressing, dried, and then heat-treated at 750 ℃ for 60 minutes in a nitrogen atmosphere. And determining the content of various metal ions in the finally processed solid product by adopting inductively coupled plasma atomic emission spectrometry (ICP-AES), wherein the solid sample needs to be subjected to digestion treatment before testing, and the digestion treatment is operated according to a standard method US EPA 3050B. The test results of the samples are shown in table 2.
TABLE 2 test results of the samples
Note: ND means that this method was not detected.
Example 3
The coal-based activated carbon activated by potassium hydroxide or sodium hydroxide is neutralized to a surface pH value of 7.0 by dilute nitric acid (concentration), and then is prepared into water-carbon slurry with a solid content of 20 wt% with deionized water. The ratio of the ozone amount used in the ozone oxidation process to the volume of the water carbon slurry is 1.2mg/L, and the contact time of the ozone/air airflow and the water carbon slurry is 20 min. The temperature range of the heating treatment of the oxidized water-carbon slurry is 85 ℃, and the treatment time is 45 min. Most of water is removed by filter pressing, further drying is not needed, and the wet sample and deionized water are directly used for preparing the water-carbon slurry again. The ozone oxidation and the heat treatment were repeated once. The treated carbon material was subjected to filter pressing, dried, and then heat-treated at 850 ℃ for 30 minutes in a nitrogen atmosphere. And determining the content of various metal ions in the finally processed solid product by adopting inductively coupled plasma atomic emission spectrometry (ICP-AES), wherein the solid sample needs to be subjected to digestion treatment before testing, and the digestion treatment is operated according to a standard method US EPA 3050B. The test results of the samples are shown in table 3.
TABLE 3 test results of the samples
Note: ND means that this method was not detected.
Example 4
Potassium hydroxide or sodium hydroxide activated coal-based activated carbon was neutralized with dilute nitric acid (concentration) to a surface pH of 7.0, and then mixed with deionized water to prepare a water carbon slurry (solid content as shown in table 4). The ratio of the ozone amount used in the ozone oxidation process to the volume of the water carbon slurry is 1.2mg/L, and the contact time of the ozone/air airflow and the water carbon slurry is 20 min. The temperature range of the heating treatment of the oxidized water-carbon slurry is 85 ℃, and the treatment time is 45 min. Most of water is removed by filter pressing, further drying is not needed, and the wet sample and deionized water are directly used for preparing the water-carbon slurry again. The ozone oxidation and the heat treatment were repeated once. The treated carbon material was subjected to filter pressing, dried, and then heat-treated at 750 ℃ for 60 minutes in a nitrogen atmosphere. And determining the content of various metal ions in the finally processed solid product by adopting inductively coupled plasma atomic emission spectrometry (ICP-AES), wherein the solid sample needs to be subjected to digestion treatment before testing, and the digestion treatment is operated according to a standard method US EPA 3050B. The test results of the samples are shown in table 4.
TABLE 4 test results for the samples
Example 5
The coal-based activated carbon activated by potassium hydroxide or sodium hydroxide is neutralized to a surface pH value of 7.0 by dilute nitric acid (concentration), and then is prepared into water-carbon slurry with a solid content of 20 wt% with deionized water. The ozone oxidation process is carried out in a contact reactor by the ratio of the ozone amount to the water carbon slurry volume. The temperature range of the heating treatment of the oxidized water-carbon slurry is 85 ℃, and the treatment time is 45 min. Most of water is removed by filter pressing, further drying is not needed, and the wet sample and deionized water are directly used for preparing the water-carbon slurry again. The ozone oxidation and the heat treatment were repeated once. The treated carbon material was subjected to filter pressing, dried, and then heat-treated at 750 ℃ for 60 minutes in a nitrogen atmosphere. And determining the content of various metal ions in the finally processed solid product by adopting inductively coupled plasma atomic emission spectrometry (ICP-AES), wherein the solid sample needs to be subjected to digestion treatment before testing, and the digestion treatment is operated according to a standard method US EPA 3050B. The test results of the samples are shown in table 5.
Table 5 test results of the samples
Note: ND means that this method was not detected.
Example 6
The coal-based activated carbon activated by potassium hydroxide or sodium hydroxide is neutralized to a surface pH value of 7.0 by dilute nitric acid (concentration), and then is prepared into water-carbon slurry with a solid content of 20 wt% with deionized water. The ratio of the ozone amount used in the ozone oxidation process to the volume of the water carbon slurry is 1.2mg/L, and the contact time of the ozone/air airflow and the water carbon slurry is 20 min. And heating the oxidized water-carbon slurry for a period of time. Most of water is removed by filter pressing, further drying is not needed, and the wet sample and deionized water are directly used for preparing the water-carbon slurry again. The ozone oxidation and the heat treatment were repeated once. The treated carbon material was subjected to filter pressing, dried, and then heat-treated at 750 ℃ for 60 minutes in a nitrogen atmosphere. And determining the content of various metal ions in the finally processed solid product by adopting inductively coupled plasma atomic emission spectrometry (ICP-AES), wherein the solid sample needs to be subjected to digestion treatment before testing, and the digestion treatment is operated according to a standard method US EPA 3050B. The test results of the samples are shown in table 6.
Table 6 test results of the samples
Note: ND means that this method was not detected.
The invention adopts an ozone contact oxidation method to carry out surface oxidation treatment on the carbon raw material, simultaneously converts partial transition metal elements into high-valence oxygen-containing negative ions, eliminates the electrostatic action between functional groups on the surface of the raw material and metal ions, and ensures that trace metal ions can be directly eluted and removed. The method for removing the metal ions can control the sum of the contents of various metal ions within a very low range (less than 60ppm) without repeatedly treating the material, and does not need repeated acid washing, so that a large amount of acid-containing wastewater is not generated, and the method is more energy-saving and environment-friendly. The existing method adopting oxidation and acid washing can only control the sum of the total concentration of metal ions to be 150-200 ppm, and even to be 300-400 ppm even though the method adopts repeated acid washing, which is far higher than the sum of the total concentration of the metal ions (less than 60ppm) in the electrode material obtained by the removal method of the invention.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (10)
1. A method for removing metal ions in an electrode material is characterized by comprising the following steps:
step 1: preparing water carbon slurry;
step 2: carrying out surface oxidation treatment on the raw material carbon in the water carbon slurry by adopting an ozone contact oxidation method;
and step 3: and heating the water carbon slurry subjected to ozone contact treatment.
2. The method for removing metal ions from an electrode material according to claim 1, wherein in the step 1, the solid content in the water carbon slurry is 5-30 wt%.
3. The method for removing metal ions from an electrode material according to claim 1, wherein the step 3 is followed by the steps of:
and 4, step 4: filtering, and reconfiguring the wet sample and deionized water to obtain secondary water-carbon slurry;
and 5: carrying out surface oxidation treatment on the raw material carbon in the secondary water carbon slurry by adopting an ozone contact oxidation method;
step 6: and heating the secondary water-carbon slurry subjected to ozone contact treatment.
4. The method for removing metal ions from an electrode material according to claim 1, wherein in the step 1, the carbon used for preparing the aqueous carbon slurry is a carbon raw material subjected to alkali activation treatment.
5. The method for removing the metal ions from the electrode material according to claim 4, wherein the method comprises neutralizing the carbon raw material subjected to the alkali activation treatment until the surface of the carbon raw material is neutral, before the step 1.
6. The method for removing metal ions from an electrode material according to claim 1, wherein the ozone content in the water carbon slurry in the step 2 is 0.5-2.0 mg/L.
7. The method for removing metal ions from an electrode material according to claim 1, wherein the heating temperature in step 3 is 70 to 95 ℃ and the heating time is 30 to 90 minutes.
8. The method for removing metal ions from an electrode material according to claim 1, wherein the step 3 comprises stirring during the heating treatment.
9. A super capacitor, wherein the electrode material of the super capacitor is activated carbon, and trace metal ions in the activated carbon are removed by the method of claims 1-8.
10. The supercapacitor according to claim 9, wherein the sum of the total concentration of metal ions in the activated carbon is less than 60 ppm.
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| JPH0692614A (en) * | 1992-09-08 | 1994-04-05 | Kobe Steel Ltd | Ozone decomposer and its production |
| CN1220237A (en) * | 1998-11-09 | 1999-06-23 | 郭梦熊 | Active carbon high-temp. chlorinating deliming technology |
| CN102149634A (en) * | 2008-09-16 | 2011-08-10 | 吉坤日矿日石能源株式会社 | Carbon material for electric double layer capacitor and process for producing the carbon material |
| CN104471760A (en) * | 2012-09-06 | 2015-03-25 | 株式会社吴羽 | Method for producing carbonaceous material for negative electrodes of nonaqueous electrolyte secondary batteries |
| CN105236404A (en) * | 2015-08-20 | 2016-01-13 | 深圳市贝特瑞新能源材料股份有限公司 | Petroleum coke based activated carbon for electrode material of supercapacitor, preparation method therefor and use thereof |
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| JPH0692614A (en) * | 1992-09-08 | 1994-04-05 | Kobe Steel Ltd | Ozone decomposer and its production |
| CN1220237A (en) * | 1998-11-09 | 1999-06-23 | 郭梦熊 | Active carbon high-temp. chlorinating deliming technology |
| CN102149634A (en) * | 2008-09-16 | 2011-08-10 | 吉坤日矿日石能源株式会社 | Carbon material for electric double layer capacitor and process for producing the carbon material |
| CN104471760A (en) * | 2012-09-06 | 2015-03-25 | 株式会社吴羽 | Method for producing carbonaceous material for negative electrodes of nonaqueous electrolyte secondary batteries |
| CN105236404A (en) * | 2015-08-20 | 2016-01-13 | 深圳市贝特瑞新能源材料股份有限公司 | Petroleum coke based activated carbon for electrode material of supercapacitor, preparation method therefor and use thereof |
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