KR20020082816A - High Functional Carbon Nano-materials by Electrochemical Surface Treatment of Alkaline Metals and Preparation Method Thereof - Google Patents

Abstract

PURPOSE: A preparation method of a high functional carbon nano-material which gives polarity onto the surface of carbon, increases surface activity and dissociation energy and substantially improves selective adsorption performance through surface treatment by electrolysis using alkaline transition metal elements is provided. CONSTITUTION: The preparation method of a high functional carbon nanotube(5) is characterized in that adsorption selectivity of the carbon nanotube(5) of which the nanoporous structure having high specific surface area is well developed is improved through the surface treatment by electrolysis using an aqueous solution of alkaline transition metals as an electrolyte(6), wherein adsorption selectivity of the carbon nanotube(5) is improved through the surface treatment by electrolysis using an aqueous solution of alkaline transition metals such as copper, nickel and silver as an electrolyte(6), a carbon nano-material the surface of which is treated by an alkaline electrolyte(6) is formed in a granule or fiber shape, time for performing the surface treatment by alkaline electrolysis is 5 to 60 minutes, and content of each of the alkaline transition metal elements on the surface of the carbon nanotube(5) by alkaline electrolytic surface treatment is 1.0 to 10.0 wt.%.

Description

High Functional Carbon Nano-materials by Electrochemical Surface Treatment of Alkaline Metals and Preparation Method Thereof}

The present invention relates to NOx, SOx and organic oxides, which are polar pollutants in the gas phase, by the surface treatment method by electrolysis using copper, nickel and silver among alkaline transition metal elements with respect to high temperature purified particulate and fibrous carbon nanotubes. The present invention relates to a method for producing activated carbon having improved selective adsorption capacity for VOCs.

Adsorption / removal technology for various environmental pollutants with polarity is affected by physical adsorption performance according to the pore structure of the adsorbent and the chemical properties of the surface. Existing treatment methods for imparting polarity to the adsorbent surface include Impregnation treatment with acid and alkaline solution at room temperature, introduction of oxygen functional groups by oxygen and ozone treatment at high temperature, surface treatment by electrolysis of acid and alkali electrolytic solutions and electroplating with oxidative metal catalysts are known. However, a method for imparting polarity to the surface of the carbon nanomaterial by electrolysis of alkaline transition metals such as copper, nickel and silver according to the present invention has not been reported. In addition, the plating of metal ions on the adsorbent has been used to selectively adsorb and remove heavy metal contaminants from wastewater and wastewater discharged from mines and industrial complexes, but the metal for plating by the surface properties of the adsorbent itself is used. The types of were limited and generally limited to adsorption and removal in the liquid phase. In addition, the surface treatment of the carbon nanomaterial of the alkali transition metals such as copper, nickel and silver by the electrolysis according to the present invention had a disadvantage that the adsorption performance is reduced by the surface-treated metal ions, so that the function as an adsorbent is deteriorated Due to the surface polarity effect of plated metal ions while maintaining the adsorption performance as an adsorbent, it has excellent adsorption selectivity against gaseous pollutants such as SOx, NOx and organic oxides (VOCs) in the liquid as well as in the air. have.

The present invention provides a highly specific surface area of particulate and fibrous carbon nanotubes well-developed nanoporous structure through the alkali metal surface treatment by electrolysis, SOx having a polarity while maintaining the adsorption performance without changing the surface structure, An object of the present invention is to provide a highly functional carbon nanomaterial having a selective adsorption characteristic for air pollutants such as NOx and organic oxides (VOCs), and a method of manufacturing the same.

1 is an electrochemical surface treatment apparatus according to the present invention

2 is a view showing the NOx conversion rate of particulate carbon nanotubes according to the untreated, Examples 1, 2 and 5, 6 of the present invention.

3 is a view showing the SOx conversion rate of particulate carbon nanotubes according to the untreated, Examples 1, 2 and 5, 6 of the present invention.

4 is a view showing the NOx conversion rate of the fibrous carbon nanotubes according to the untreated and Examples 3 and 4 of the present invention.

5 is a view showing the SOx conversion rate of the fibrous carbon nanotubes according to the untreated and Examples 3, 4 of the present invention

* Explanation of symbols for main parts of representative drawings

1: surface treatment electrolytic bath, 2: graphite negative electrode plate, 3: graphite negative electrode grounding strap,

4: graphite screen box, 5: particle and fibrous carbon nanotubes, 6: electrolyte

In the present invention, the high specific surface area well-developed nanoporous carbon nanotubes of the particulate and fibrous carbon nanotubes in the aqueous solution of alkali transition metals such as copper, nickel and silver for 5 to 60 minutes, respectively, by surface treatment by electrolysis Provided is a method for producing a high functional carbon nanomaterial having excellent adsorption selectivity with respect to inorganic adsorbates.

In general, alkaline transition metals such as copper, nickel, and silver are suitable as surface-treated metal elements by electrolysis. This alkaline transition metal has a high reduction potential, and thus surface treatment of the adherend with a metal in an ionic state by a reducing agent in an aqueous solution is possible, and the selective functionality by the surface-treated metal element can be continuously maintained.

In the surface treatment according to the present invention, the basic composition of the electrolytic copper aqueous solution is 1.0 mol of copper sulfate (CuSO 수) solution, and ethylene diacetate triacetate (EDTA) and formaldehyde (HCHO) are each used as molar ratios of 2: 1. ), An alkaline solution having a pH of about 12 was prepared and used as an electroless copper plating solution. In this case, bipyridyl and potassium tetradionate nickel (II) acid were used as additives to prevent decomposition reaction at high temperature. 10 mg / l each was added.

In electrolytic nickel surface treatment according to the present invention, the basic composition of the aqueous solution is 1.0 M aqueous nickel chloride (NiCl₂) solution with sodium hypophosphite (NaH₂PO₂) and ammonium chloride (NH₄Cl) as a reducing agent, respectively, at a molar ratio of 1: 5. An aqueous alkaline nickel solution of about 9 was prepared and used. In addition, the basic composition of the electrolytic silver aqueous solution according to the present invention was prepared by mixing a 0.2 M silver nitrate (AgNO₃) solution with an appropriate amount of ammonia water and a solution of 40: 1 formalin 40 ml as a reducing agent in 200 ml of distilled water to prepare a solution of electrolytic silver solution Used as.

The surface treatment time according to each experiment is preferably 5 to 60 minutes. If the treatment time is less than 5 minutes, the surface of the adherent particulate and fibrous carbon nanotubes is not sufficiently treated, and the surface polarity due to the surface-treated metal element is not well developed, so that excellent selective functionality cannot be continuously expressed. If the time exceeds 60 minutes, it is not preferable because the surface etching of the metal element reduces the pore structure and the adsorption surface area developed on the surface of the carbon material, so that sufficient adsorption performance cannot be exhibited.

It is preferable that the content of each metal component according to the elemental analysis of the highly functional carbon nanomaterial by the surface treatment of the electrolytic alkaline transition metal is 1 to 10%. If the metal content is less than 1.0%, the surface of the carbon nanomaterial to be deposited is not sufficiently treated, so that the surface polarity due to the metal element is not well developed, so that excellent adsorption selectivity cannot be maintained continuously, and the content is more than 10%. It is not preferable to reduce the pore structure and adsorption surface area developed on the surface of the carbon material by surface etching of the metal element, so that sufficient adsorption performance cannot be exhibited.

Embodiments of the present invention are as follows, but the scope of the present invention is not limited to the embodiments.

Example 1

Electrolytic treatment was performed in alkaline copper aqueous solution using high purity purified particulate carbon nanotubes having a specific surface area of 682 m 2 / g, pore volume of 0.68 cm 3 / g and nanopore fraction of 93% or more. In the surface treatment, the basic composition of the copper electrolyte was firstly prepared in a 1.0 M copper sulfate (CuSO₄) solution with ethylene diamine triacetate (EDTA) and formaldehyde (HCHO) as a molar ratio of 2: 1, respectively. Alkaline copper electrolyte of about 12 was prepared and used, and 10 mg / l of bipyridyl and potassium tetradionickel (II) acid were added as additives to prevent decomposition reaction at high temperature. . Carbon nanotubes were placed in a copper aqueous solution prepared at room temperature of about 20 ° C. and surface treated for about 5 minutes. Table 1 shows the adsorption specific surface area, iodine adsorption amount and plated copper element content of the treated carbon nanotubes, respectively. As a result, the BET specific surface area and the iodine adsorption amount in the liquid phase did not change significantly, but the content of copper element on the surface of the carbon nanotubes increased to 1.0%. As a result, the NOx and SOx conversion rates in the air are shown in FIGS. 2 and 3, respectively, and the NOx conversion rate is increased by at least 140% and the SOx conversion is increased by at least 175% according to the waiting time in the atmosphere.

Example 2

As in Example 1, the basic composition of the electrolytic solution in the copper element surface treatment by electrolysis was the same as in Example 1, and the particulate carbon nanotubes were surface treated for about 30 minutes at a solution temperature of about 60 ° C., and treated carbon The adsorption specific surface area, iodine adsorption amount, and treated copper element content of the nanotubes are shown in Table 1, respectively. As a result, the BET specific surface area and the iodine adsorption amount in the liquid phase did not change significantly, but the content of copper element on the surface of the turno nanotubes increased to 5.0%. As a result, the NOx and SOx conversion rates in the air are shown in FIGS. 2 and 3, respectively, and the NOx conversion rate is increased by at least 180% and the SOx conversion is increased by at least 230% according to the waiting time in the air.

Example 3

Electrolytic treatment was performed in alkaline nickel aqueous solution using high-purity purified fibrous carbon nanotubes with a specific surface area of 865 m² / g, pore volume of 0.75 cm³ / g and nanopore fraction of at least 95%. In the surface treatment, the basic composition of nickel electrolyte is alkaline solution with pH of about 9 with 1.0M aqueous nickel chloride (NiCl₂) solution as the molar ratio of sodium hypophosphite (NaH₂PO₂) and ammonium chloride (NH₄Cl) as 1: 5 respectively. Nickel electrolyte was prepared and used. Fibrous carbon nanotubes were placed in a nickel electrolyte prepared at room temperature of about 40 ° C. and surface treated for about 15 minutes. Table 1 shows the adsorption specific surface area, iodine adsorption amount and treated nickel element content of the treated carbon nanotubes, respectively. . As a result, the BET specific surface area and the iodine adsorption amount in the liquid phase did not change significantly, but the content of nickel element treated on the surface of the turno nanotube increased to 3.0%. Accordingly, the atmospheric NOx and SOx conversion rates are shown in FIGS. 4 and 5, respectively, and the NOx conversion rate is increased by at least 160% and the SOx conversion is increased by at least 180% according to the waiting time in the atmosphere.

Example 4

As in Example 3, the basic composition of the electrolytic solution in the nickel element surface treatment by electrolysis was the same as in Example 3, and the fibrous carbon nanotubes were added at a solution temperature of about 80 ° C. and surface treated for about 45 minutes. The adsorption specific surface area, iodine adsorption amount and treated nickel element content of the nanotubes are shown in Table 1, respectively. As a result, the BET specific surface area and the iodine adsorption amount in the liquid phase did not change significantly, but the content of nickel element treated on the surface of the carbon nanotubes increased to 7.5%.

As a result, the NOx and SOx conversion rates in the air are shown in FIGS. 4 and 5, respectively, and the NOx conversion rate is increased by at least 190% and the SOx conversion is increased by at least 240% according to the waiting time in the air.

Example 5

Electrolytic treatment was performed in alkaline silver aqueous solution using high purity purified particulate carbon nanotubes having a specific surface area of 682 m 2 / g, pore volume of 0.68 cm 3 / g and nanopore fraction of 93% or more as in Example 1. In the surface treatment, the basic composition of the silver electrolyte solution was prepared by mixing 0.2 M silver nitrate (AgNO₃) solution with ammonia water and 200 ml of distilled water and 5: 1 mixture of 40 ml of formalin as a reducing agent. It was. Particulate carbon nanotubes were put in a silver electrolyte prepared at room temperature of about 40 ° C. and surface treated for about 15 minutes. Table 1 shows the adsorption specific surface area, iodine adsorption amount and treated silver element content of the treated carbon nanotubes, respectively. . As a result, the BET specific surface area and the iodine adsorption amount in the liquid phase did not change significantly, but the content of silver element treated on the surface of the carbon nanotubes increased to 3.0%. As a result, the NOx and SOx conversion rates in the air are shown in FIGS. 2 and 3, respectively, and the NOx conversion rate is increased by at least 160% and the SOx conversion is increased by at least 210% according to the waiting time in the atmosphere.

Example 6

As in Example 5, the basic composition of the electrolyte in the surface treatment of the silver element by electrolysis was the same as that of Example 5, and the plated carbon nanotubes were plated for about 60 minutes at a solution temperature of about 100 ° C. The adsorption specific surface area, iodine adsorption amount and treated silver element content of the nanotubes are shown in Table 1, respectively. As a result, the BET specific surface area and the amount of iodine adsorption in the liquid phase did not change significantly, but the content of silver element treated on the surface of the carbon nanotubes increased to 10.0%.

As a result, the NOx and SOx conversion rates in the air are shown in FIGS. 2 and 3, respectively. The NOx conversion rate increased by 190% or more and the SOx conversion rate increased by 240% or more according to the waiting time in the air.

Each carbon nanomaterial electrolytically surface-treated was washed 2-3 times with distilled water at room temperature and then dried in a drying furnace at 100 ° C. for at least 24 hours. Particulate and fibrous carbon nanotubes obtained in Examples 1 to 6 were used. And the adsorption specific surface area, iodine adsorption capacity and the content of the treated component of the conventional untreated carbon nanotubes were analyzed, and the results are shown in Table 1 below.

<Table 1>

* Each measured value represents the average value according to the Example.

The particulate and fibrous carbon nanotubes electrolytically treated with alkaline transition metals according to the respective embodiments have a physical change such as surface structure, that is, adsorption specific surface area and pore structure, compared with conventional untreated carbon nanotubes. There was no significant difference, and accordingly, there was no significant difference in iodine adsorption capacity. However, the development of surface polarity due to the surface-treated metal element was remarkable, and thus the conversion of NOx and SOx in the gas phase was greatly improved.

As described above, the surface treatment method by electrolysis of alkaline transition metal according to the present invention selectively adsorbs to NOx, SOx and organic oxides (VOCs), which are pollutants in the gas phase with relative polarity, with almost no change in adsorption performance. A highly functional carbon nanomaterial was prepared with greatly improved performance.

Claims (5)

Highly functional carbon nanotubes with a high specific surface area nanoporous structure developed by using an alkaline transition metal solution as an electrolytic solution to improve the adsorption selectivity through surface treatment by electrolysis method and a method of manufacturing the same The method according to claim 1, wherein copper, nickel and silver are used as the alkaline transition metals as aqueous solutions, and the high-performance carbon nanotubes having improved adsorption selectivity through surface treatment by an electrolysis method and a method of manufacturing the same. The method of claim 1, wherein the carbon nanomaterials surface-treated with an alkali electrolyte solution are particulate and fibrous, and the high-performance carbon nanotubes having improved adsorptive selectivity and a method of manufacturing the same are provided. The method of claim 1, wherein the surface treatment time by alkali electrolysis is 5 to 60 minutes, and the high-performance carbon nanotubes having improved adsorptive selectivity and a method of manufacturing the same. According to claim 1, High functional carbon nanotubes having improved adsorption selectivity, and a method for producing the alkali transition metal surface element content of 1.0 to 10.0% by alkali electrolysis surface treatment method