WO2023128493A1 - Method for producing graphitic carbon nitride by using hard template method for decomposition of organic contaminants - Google Patents

Method for producing graphitic carbon nitride by using hard template method for decomposition of organic contaminants Download PDF

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WO2023128493A1
WO2023128493A1 PCT/KR2022/021226 KR2022021226W WO2023128493A1 WO 2023128493 A1 WO2023128493 A1 WO 2023128493A1 KR 2022021226 W KR2022021226 W KR 2022021226W WO 2023128493 A1 WO2023128493 A1 WO 2023128493A1
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template
composite
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이병규
에스팔리세예대 말리헤 라자비
전익수
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울산대학교 산학협력단
다담마이크로 주식회사
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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
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/0605—Binary compounds of nitrogen with carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/24—Nitrogen compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/39—Photocatalytic properties
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/14—Pore volume
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/16—Pore diameter

Definitions

  • This application relates to a method for producing graphitic carbon nitride using a hard template method for decomposing organic pollutants.
  • organic pollutants such as dyes, antibiotics, and phenols are released into the environment every year from various industries, including the pharmaceutical industry, food industry, and fish and shrimp aquaculture.
  • the discharge of organic pollutants generated in the cleaning process of industrial sites into natural waters accompanies serious environmental problems and has serious adverse effects on humans, animals, and the entire ecosystem.
  • AOP advanced oxidation process
  • photocatalytic decomposition by semiconductor catalysts has emerged as a method to remove harmful pollutants because it is simple in design, renewable, inexpensive, non-toxic, and does not cause serious secondary pollution.
  • gC 3 N 4 graphitic carbon nitride
  • a layered metal-free polymeric semiconductor has attracted much attention in many fields such as water decomposition, photolysis of environmental organic pollutants, organic synthesis, and CO 2 reduction.
  • gC 3 N 4 has excellent properties such as visible light responsiveness, extreme stability, non-toxicity, easy manufacturing, and low-cost manufacturing.
  • conventional bulk gC 3 N 4 has generally been limited by unfavorable photocatalytic efficiency due to high recombination rate of photoinduced charge, small specific surface area and insufficient solar absorption.
  • Various modification approaches including nanostructure design, elemental and molecular doping, supramolecular preorganization, interface engineering, and dye sensitization have been studied to compensate for the above disadvantages and improve photocatalytic performance.
  • the present application relates to a method for preparing nanostructured porous graphitic nitride having nitrogen defects in order to simultaneously improve the active site, light absorption efficiency and charge separation ability of a catalyst.
  • One aspect of the present application relates to a method for producing graphitic carbon nitride.
  • the manufacturing method may include forming a gC 3 N 4 and SiO 2 complex; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • the manufacturing method comprises preparing a SiO 2 cluster template by drying and pulverizing the colloidal SiO 2 dispersion ; Preparing a mixture by mixing the SiO 2 template and melamine; heating the mixture to form a gC 3 N 4 and SiO 2 composite; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • the colloidal SiO 2 dispersion may be dried in an oven at 80 to 120 °C.
  • the colloidal SiO 2 dispersion may be dried for 10 to 14 hours.
  • the SiO 2 template and melamine may be mixed in a weight ratio of 1:1 to 1.5.
  • the mixture may be heated to 550 °C and held for 2 to 4 hours to form a gC 3 N 4 and SiO 2 composite.
  • a hydrogen fluoride (HF) solution may be added to remove the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • the manufacturing method includes preparing SiO 2 microspheres; preparing a mixture by mixing molten cyanamide with SiO 2 microspheres; heating the mixture to form a gC 3 N 4 and SiO 2 composite; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • the weight ratio of cyanamide and silica microspheres may be 1:0.1 to 2.5.
  • the average diameter of the silica microspheres may be 200 to 400 nm.
  • the mixture may be mixed at 70 to 90 °C for 20 to 40 minutes, cooled, and then heated again at 500 to 600 °C to form a gC 3 N 4 and SiO 2 composite.
  • the SiO 2 template may be removed from the gC 3 N 4 and SiO 2 complex by adding an ammonium hydrogen difluoride solution.
  • Another aspect of the present application relates to graphitic carbon nitride produced by this production method.
  • the average volume of pores may be 0.2 to 0.3 cm 3 g -1 .
  • the average diameter of the pores may be 10 to 20 nm.
  • the BET specific surface area may be 30 to 70 m 2 g -1 .
  • Another aspect of the present application relates to a visible ray photocatalyst including such graphitic carbon nitride.
  • an organic nano photocatalyst design of a desired shape by creating an inverse opal structure in a hard template technique (silica microspheres).
  • FIG. 1 is a schematic diagram for explaining a method for synthesizing graphitized carbon nitride using a hard template method.
  • Fig. 2a is a SEM image of SiO2 cluster
  • Fig. 2b is a SEM image of NC MCN
  • Fig. 2c is an SEM image of bulk CN
  • Figs. 2d to 2h are TEM images of NC MCN.
  • Figure 3a is a SEM image of SiO2 microspheres
  • Figure 3b is a SEM image of IO CN 1:0.5
  • Figure 2c is a SEM image of IO CN 1:1
  • Figures 2d and 2e are SEM images of IO CN 1:2
  • 2f is a TEM image of IO CN 1:2.
  • Figure 4a shows the N2 adsorption/desorption isotherms of NC MCN and bulk CN
  • Figure 4b shows the corresponding pore size distribution curves.
  • Figure 5a shows the N2 adsorption/desorption isotherms of IO CN and bulk CN
  • Figure 5b shows the corresponding pore size distribution curves.
  • Figure 6a is a photocatalytic degradation curve of rhodamine B (RhB) degradation
  • Figure 6b is a photocatalytic degradation curve of tetracycline (TC) degradation
  • Figure 6c is a pseudo first-order kinetic curve of photocatalytic degradation for rhodamine
  • Figure 6d is a pseudo first-order kinetic curve of photocatalytic degradation for tetracycline.
  • FIG. 10a is a UV-Vis absorption spectrum of MB in the presence of IOCN 1:2
  • FIG. 10b is a photocatalytic decomposition curve for MB decomposition in the presence of a prepared photocatalyst.
  • FIG. 11a is a UV-Vis absorption spectrum of RhB in the presence of IOCN 1:2
  • FIG. 11b is a photocatalytic decomposition curve for RhB decomposition in the presence of a prepared photocatalyst.
  • Figure 16 shows the toxicity evaluation results of TC intermediates produced by photocatalytic degradation using NC MCN (a) acute toxicity LD50; (b) bioaccumulation coefficient; (c) It is a graph for developmental toxicity (d) mutagenicity.
  • nano may refer to a size in a nanometer (nm) unit, for example, from 1 to 1,000 nm, but is not limited thereto.
  • nanoparticle in this specification may mean a particle having an average particle diameter in nanometer (nm) units, for example, may mean a particle having an average particle diameter of 1 to 1,000 nm, but It is not limited.
  • One aspect of the present application relates to a method for producing graphitic carbon nitride.
  • the manufacturing method may include forming a gC 3 N 4 and SiO 2 complex; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • the manufacturing method comprises preparing a SiO 2 cluster template by drying and pulverizing the colloidal SiO 2 dispersion ; Preparing a mixture by mixing the SiO 2 template and melamine; heating the mixture to form a gC 3 N 4 and SiO 2 complex; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • the colloidal SiO 2 dispersion may be dried in an oven at 80 to 120 °C. In one example, the colloidal SiO 2 dispersion may be dried for 10 to 14 hours.
  • the SiO 2 template and melamine may be mixed in a weight ratio of 1:1 to 1.5. In one example, the mixture may be heated to 550 °C and held for 2 to 4 hours to form a gC 3 N 4 and SiO 2 composite.
  • a hydrogen fluoride (HF) solution may be added to remove the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • mesoporous gC 3 N 4 a colloidal silica dispersion (12 nm, Ludox HS-40, 40% wt.% aqueous suspension) was dried in an oven at 100° C. for 12 hours and then ground in a mortar.
  • the resulting SiO 2 cluster template (1.5 g) was thoroughly mixed with melamine (1.5 g) and transferred to a crucible. The mixture is then heated from room temperature to 550° C. in air for 4 hours and held at this temperature for 3 hours.
  • the resulting yellow gC 3 N 4 /SiO 2 hybrid was added to 40 mL of 10% HF solution for 24 hours to remove the silica template.
  • NC MCN a reference sample
  • 1.5 g of melamine was calcined with the same heat treatment as before to synthesize bulk gC 3 N 4 , which is referred to as bulk CN.
  • the manufacturing method may include preparing SiO 2 microspheres; preparing a mixture by mixing molten cyanamide with SiO 2 microspheres; heating the mixture to form a gC 3 N 4 and SiO 2 composite; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  • the weight ratio of cyanamide and silica microspheres may be 1:0.5 to 2.5.
  • the average diameter of the silica microspheres may be 200 to 400 nm.
  • the mixture may be mixed at 70 to 90 °C for 20 to 40 minutes, cooled, and then heated again at 500 to 600 °C to form a gC 3 N 4 and SiO 2 composite.
  • the SiO 2 template may be removed from the gC 3 N 4 and SiO 2 complex by adding an ammonium hydrogen difluoride solution.
  • solution A was prepared by mixing 154 ml of ammonia water, 304 ml of ethanol, and 370 ml of deionized water in a stirrer for 10 minutes.
  • Solution B containing 683 ml of ethanol and 67 ml of tetraethoxysilane (TEOS) is added to solution A in about 1 minute, during which the solution is vigorously stirred (800 r/min). Then, the solution is kept under magnetic stirring (400 r/min) for 16 hours to allow growth of silica particles.
  • TEOS tetraethoxysilane
  • the white precipitate was collected by centrifugation (11000 rpm), washed three times with water and ethanol, mixed with 100 ml of ethanol, sonicated for 15 min, and dried in an oven at 100 °C. Finally, the prepared white solid is ground in a mortar and heated in air from room temperature to 550° C. for 4 hours and held at this temperature for 6 hours to obtain monodispersed SiO 2 microspheres.
  • FIG. 1 is a schematic diagram for explaining a method for synthesizing graphitized carbon nitride using a hard template method.
  • Cyanamide is used as a precursor to synthesize the inverse opal structure of gC 3 N 4 .
  • the resulting yellow sample of the gC 3 N 4 /SiO 2 complex was mixed with 40 ml of 4M ammonium bifluoride for 48 hours to completely remove the SiO 2 hard template. Then, the suspension was washed several times with distilled water until the pH reached 7 and then dried in an oven at 80 °C for 24 hours.
  • the obtained catalyst is referred to as IO CN x:y, where x and y are the mass ratios of cyanamide:silica microspheres, which are IO CN 1:0.5 (IO CN1), IO CN 1:1 (IO CN2), IO CN 1:2 (IO CN3).
  • bulk gC 3 N 4 is synthesized by calcining cyanamide without silica particles using the same heat treatment method represented by bulk CN.
  • the average volume of pores may be 0.2 to 0.3 cm 3 g -1 .
  • the average diameter of the pores may be 10 to 20 nm.
  • the BET specific surface area may be 30 to 70 m 2 g -1 .
  • Another aspect of the present application relates to a visible ray photocatalyst including such graphitic carbon nitride.
  • FIGS. 2d to 2h are TEM images of NC MCN.
  • FIG. 2a is a SEM image of SiO 2 clusters after drying. As shown in FIG. 2A, formation of silica clusters can be confirmed through adhesion and aggregation of small silica nanoparticles. After mixing the SiO 2 clusters with melamine, the growth of gC 3 N 4 planes during firing is limited and controlled according to the shape of the silica clusters.
  • Figure 2b shows the obtained morphology of NC MCN.
  • gC 3 N 4 synthesized without using silica clusters shows a highly layered structure in FIG. 2c.
  • the internal structure and shape of the NC MCN can be further confirmed, which confirms the configuration of small clusters and mesoporous architecture.
  • the content of cyanamide and silica is 1:0.1 to 2.5, preferably 1:0.5, 1:1, and 1:2, more preferably 1:2.
  • FIG. 3a is a SEM image of SiO 2 microspheres
  • FIG. 3b is a SEM image of IO CN 1:0.5
  • FIG. 2c is a SEM image of IO CN 1:1
  • FIGS. 2d and 2e are SEM images of IO CN 1:2 SEM image
  • Fig. 2f is a TEM image of IO CN 1:2.
  • the SEM image of SiO 2 microspheres at an average size of 300 nm confirms a uniform spherical configuration.
  • 3b is a SEM image of inverse opal gC 3 N 4 synthesized using a cyanamide/SiO 2 mass ratio of 1/0.5.
  • 3c is for a cyanamide/SiO 2 mass ratio of 1/1
  • FIGS. 3d and 3e are SEM images for a cyanamide/SiO 2 mass ratio of 1/2 showing a much higher uniform structure.
  • 3f is a TEM image of IO CN3, which is considered to be a desirable sample with uniform porosity.
  • Nitrogen adsorption and desorption measurements were performed to further investigate the surface properties and porosity of the catalyst.
  • Figure 4a shows the N 2 adsorption/desorption isotherms of NC MCN and bulk CN
  • Figure 4b shows the corresponding pore size distribution curves.
  • NC MCN has very abundant mesopores in the range of 2 to 20 nm compared to bulk CN.
  • pores larger than 20 nm exist up to 80 nm in the sample, which is due to the reverse radiation of silica clusters of various sizes.
  • Pore volume (cm 3 g -1 ) Pore diameter (nm) BET surface area (m 2 g -1 ) NC MCN 0.226 17.66 51.34 bulk CN 0.126 23.63 21.49
  • NC MCN consistently exhibited a specific surface area of 51.34 m 2 g -1 and a pore volume of 0.226 cm 3 g -1 , which was comparable to bulk CN (21.49 m 2 g -1 , 0.126 cm 3 g -1 ), supporting the fact that the use of silica clusters as a hard template can generate a large mesoporous structure with increased surface area and enlarged pore volume.
  • Figure 5a shows the N 2 adsorption/desorption isotherms of IO CN and bulk CN
  • Figure 5b shows the corresponding pore size distribution curves.
  • the plots of the two catalysts showed a typical type IV isotherm with an H3 hysteresis loop in the range of 0.4-0.95P/P0 based on the International Union of Pure and Applied Chemistry (IUPAC) classification, confirming the presence of a mesoporous structure.
  • IUPAC International Union of Pure and Applied Chemistry
  • the BJH pore size distribution also confirmed that IOCN 1:2 had very abundant mesopores in the range of 2 to 80 nm compared to other samples.
  • Pore volume (cm 3 g -1 ) Pore diameter (nm) BET surface area (m 2 g -1 ) IO CN3 0.25 15 66.77 IO CN2 0.12 13.56 37.5 IO CN1 0.12 14.8 33.34 bulk CN 0.035 21.43 6.5
  • IO CN3 exhibited a specific surface area of 66.77 m 2 g -1 and a pore volume of 0.25 cm 3 g -1 , which were higher than other samples. Through this, it can be confirmed that a hierarchical mesoporous structure with an increased surface area and an enlarged pore volume can be generated when silica microspheres are used as a hard template.
  • CO (mgL -1 ) is the starting concentration of the organic pollutant and C n is the pollutant concentration after irradiation time t.
  • RhB RhB
  • TC TC
  • MB MB
  • Figure 6a is a photocatalytic degradation curve of rhodamine B (RhB) degradation
  • Figure 6b is a photocatalytic degradation curve of tetracycline (TC) degradation
  • Figure 6c is a pseudo first-order kinetic curve of photocatalytic degradation for rhodamine
  • Figure 6d is a pseudo first-order kinetic curve of photocatalytic degradation for tetracycline.
  • NC MCN showed a significant increase in adsorption compared to bulk CN under the same conditions after 30 minutes of reaction in the dark, and the adsorption and desorption equilibrium of the suspension was completely obtained. It can be observed that the degradation efficiency of bulk CN to RhB is very low and it takes too much time to completely remove RhB from the solution (see Fig. 6a). On the other hand, NC MCN significantly shortened this time, and RhB was completely decomposed within 30 minutes under visible light irradiation.
  • TC decomposition is shown in Figure 6b.
  • the TC decomposition ability of bulk CN was very poor due to the low adsorption amount and slow removal rate.
  • NC MCN exhibited very high photocatalytic activity with over 70% degradation within 15 minutes and complete degradation within 30 minutes, which is demonstrated using LC-MS analysis (Section 3.10).
  • the photocatalytic degradation data of the two contaminants obtained within 25 minutes were suitable for a pseudo first-order kinetic reaction, which is calculated using Equation 2 below.
  • k is the first-order kinetic rate constant (min -1 )
  • C 0 and C n are the concentrations of contaminants at reaction times of 0 and n minutes, respectively.
  • NC MCN showed much higher efficiency and ability to remove RhB and TC from solution.
  • the significantly improved photocatalytic performance of NC MCN is attributed to the larger specific surface area, porous structure and introduction of nitrogen defects into the structure.
  • NC MCN photocatalytic performance of NC MCN was evaluated using MB as a contaminant.
  • the decomposition process was carried out under visible light irradiation, and the UV-vis spectrum is shown in FIG. 7 .
  • NC MCN showed a high adsorption capacity for MB.
  • Adsorption-desorption equilibrium was achieved after about 30 minutes of reaction without light irradiation (under dark conditions). Therefore, further removal of contaminants after the 30-minute adsorption experiment is mainly due to photocatalytic degradation.
  • the NC MCN catalyst showed efficient performance to completely decompose MB in a 140-minute photocatalytic reaction. However, bulk CN showed very poor performance degradation, taking more than 300 minutes to degrade 50% MB.
  • NC MCN photocatalyst The same amount of NC MCN photocatalyst as in the previous experiment was added to the solution.
  • MB has two absorption peaks between 600 and 700 nm, and RhB has one absorption peak around 550 nm.
  • 9 shows the entire spectrum from 200 nm to 800 nm. Another peak around 200 to 300 nm is generated and it can be observed that it becomes higher as the reaction proceeds. This is because, as the reaction progresses, some by-products are produced due to the decomposition of the original RhB and MB or the combination of other molecules.
  • the photocatalytic performance of inverse opal graphitic nitride was evaluated using RhB and MB as target contaminants.
  • the decomposition process was individually performed in the presence of visible light irradiation and each photocatalyst.
  • FIG. 10a is a UV-Vis absorption spectrum of MB in the presence of IOCN 1:2
  • FIG. 10b is a photocatalytic decomposition curve for MB decomposition in the presence of a prepared photocatalyst.
  • FIG. 11a is a UV-Vis absorption spectrum of RhB in the presence of IOCN 1:2
  • FIG. 11b is a photocatalytic decomposition curve for RhB decomposition in the presence of a prepared photocatalyst.
  • RhB The ability of bulk CN to decompose RhB was very poor, with a small amount of adsorption and a slow removal rate. In contrast, IO CN 1:2 exhibited a decomposition rate of over 80% within 15 minutes and complete decomposition of RhB within 25 minutes, showing very high photocatalytic activity.
  • FIG. 13 is a SEM image of an unused NC MCN and a used NC MCN.
  • NC MCN has high reusability and stability. Through this, NC MCN can be used as a stable and efficient photocatalyst for practical use of pollutant photolysis by visible light irradiation.
  • the process of the photocatalytic reaction includes (i) light harvesting; (ii) charge excitation and electron-hole pair generation; (iii) electron-hole pair separation and surface migration; (iv) consists of surface adsorption and oxidation-reduction reactions. Therefore, all these four steps were optimized in designing a NC MCN with excellent photocatalytic ability.
  • the higher specific surface area together with the porous structure of NC MCNs provides abundant exposed active sites for surface reaction and enhanced mass transfer process, indicating efficient photolysis of RhB and TC.
  • the mesoporous structure of NC MCNs has a higher accessible surface area compared to the bulk sample, enabling more efficient light harvesting and utilization.
  • NC MCN the presence of abundant cyano groups and nitrogen vacancies in the structure of NC MCN greatly enhances light harvesting and charge separation.
  • an electron can also be excited into a mid-gap state by absorbing photons of longer wavelengths.
  • the mid-gap energy state below the conduction band of NC MCN can trap electrons excited into the conduction band and prevent recombination with holes in the valence band, consequently reducing the recombination rate of photo-generated charges.
  • the trapped electrons react with dissolved oxygen in water to generate superoxide radicals that play a leading role in the decomposition of RhB and TC.
  • NC MCN is more positive compared to bulk CN, it exhibits much better oxidation ability, resulting in superior photolysis efficacy.
  • NC MCN synthesized in the present application exhibits remarkable activity in all four steps and exhibits remarkable photocatalytic activity for the decomposition of TC and RhB.
  • LC-MS liquid chromatography-mass spectrometry
  • Figure 16 shows the toxicity evaluation results of TC intermediates produced by photocatalytic degradation using NC MCN (a) acute toxicity LD50; (b) bioaccumulation coefficient; (c) It is a graph for developmental toxicity (d) mutagenicity.
  • the LD50 value of TC for rats is 806.96 mg.kg -1 , which is evaluated as "very toxic”. All other intermediates except P12 and P13 showed higher LD50 values than TC, confirming that the acute toxicity of intermediates was reduced. Although P12 and P13 are highly toxic, the major final intermediates of TC are P16, P17 and P18, which have higher LD50 values and are less toxic than TC. In addition, most of the intermediates have higher bioconcentration coefficients than TC, but the final product of P18 has a low bioaccumulation coefficient, which is advantageous (see FIG. 16b). It can be seen from FIG. 16c that the developmental toxicity of all intermediates except P3 is lower than that of TC.
  • various shapes and structures of graphitic carbon nitride photocatalysts can be synthesized using silica particles of various shapes. Both the mesoporous gC 3 N 4 nanoclusters and the inverse opal gC 3 N 4 showed excellent activity against the degradation of various organic contaminants.
  • the manufacturing method of the present application is a simple manufacturing method, and can provide easy availability of raw materials, engineering of shape and porosity of photocatalyst, improvement of photocatalyst decomposition ability of photocatalyst, high stability and reusability. These advantages make it suitable for practical applications.
  • the present application for the composition of defective shape-controlled gC 3 N 4 and the reduction of degradation, mineralization and toxicity of TC may provide a method for producing highly efficient photocatalysts for applications related to wastewater and environmental pollution remediation.

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Abstract

The present application relates to a method for producing nanostructured porous graphitic carbon nitride with nitrogen defects to improve all of the active site, light absorption efficiency, and charge separation ability of a catalyst.

Description

유기오염물질 분해를 위한 하드 템플릿 방법을 이용한 흑연질화탄소의 제조 방법Manufacturing method of graphitic carbon nitride using hard template method for organic contaminant decomposition
본 출원은 유기오염물질 분해를 위한 하드 템플릿 방법을 이용한 흑연질화탄소의 제조 방법에 관한 것이다.This application relates to a method for producing graphitic carbon nitride using a hard template method for decomposing organic pollutants.
제약 산업, 식품 산업, 어류 및 새우 양식업을 포함한 다양한 산업 분야에서 염료, 항생제, 페놀류와 같은 다양한 종류의 유기 오염물질이 환경으로 매년 유출된다. 산업현장의 세척과정에서 발생하는 유기오염물질을 자연수로 방출하는 것은 심각한 환경문제를 동반하고 인간과 동물, 생태계 전체에 심각한 악영향을 미치게 된다. Various types of organic pollutants such as dyes, antibiotics, and phenols are released into the environment every year from various industries, including the pharmaceutical industry, food industry, and fish and shrimp aquaculture. The discharge of organic pollutants generated in the cleaning process of industrial sites into natural waters accompanies serious environmental problems and has serious adverse effects on humans, animals, and the entire ecosystem.
따라서 폐수를 처리하고 유해 오염 물질을 제거할 수 있는 효율적인 방법이 절실히 필요하다. 이 문제를 해결하기 위해 주로 생물학적 처리, 흡착, 전기화학적 방법, 이온 교환 및 화학적 침전을 포함한 여러 전통적인 방법이 수행되어 왔다. 그러나 이러한 방법들은 낮은 제거 효율, 무독성 물질로의 불완전 분해, 후처리의 필요성과 함께 장시간의 제거 시간 등의 한계가 있다.Therefore, there is an urgent need for efficient methods to treat wastewater and remove harmful pollutants. Several traditional methods have been performed to solve this problem, mainly including biological treatment, adsorption, electrochemical methods, ion exchange and chemical precipitation. However, these methods have limitations such as low removal efficiency, incomplete decomposition into non-toxic substances, need for post-treatment, and long removal time.
최근에는 비파괴 수처리 방법의 대안으로 효율적인 고급 산화 공정(advanced oxidation process, AOP)을 사용하여 수용액에서 광범위한 산업 오염물질을 제거하고 있다. 초음파 화학적 분해, 오존 처리, 전기화학적 개선, 펜톤 반응 및 광촉매를 포함한 AOP는 유기 화합물 분해를 목표로 하는 고활성 라디칼 종의 현장 생산을 기반으로 한다.Recently, as an alternative to non-destructive water treatment methods, an efficient advanced oxidation process (AOP) has been used to remove a wide range of industrial pollutants from aqueous solutions. AOPs, including sonochemical degradation, ozonation, electrochemical reforming, Fenton reaction and photocatalysis, are based on the in situ production of highly active radical species targeted at the degradation of organic compounds.
이러한 AOP 중 반도체 촉매에 의한 광촉매 분해는 설계가 간단하고 재생 가능하며 비용이 저렴하고 무독성이며 심각한 2차 오염이 일어나지 않아 유해 오염 물질을 제거하는 방안으로 대두되었다.Among these AOPs, photocatalytic decomposition by semiconductor catalysts has emerged as a method to remove harmful pollutants because it is simple in design, renewable, inexpensive, non-toxic, and does not cause serious secondary pollution.
최근 TiO2, ZnO, SrTiO3와 같은 다양한 반도체 광촉매를 사용하여 RhB와 TC의 광촉매 분해가 보고된바 있다. 그러나 대부분의 경우 광촉매는 자외선에 반응하는데, 이러한 자외선은 전체 태양광 조사량의 약 5% 미만을 차지한다. 이러한 문제를 해결하기 위해 가시광선 조사에서 활성인 고효율 광촉매에 대한 연구가 필요하다.Recently, photocatalytic decomposition of RhB and TC has been reported using various semiconductor photocatalysts such as TiO 2 , ZnO, and SrTiO 3 . However, in most cases, photocatalysts respond to ultraviolet rays, which account for less than about 5% of total solar irradiation. To solve this problem, research on highly efficient photocatalysts that are active under visible light irradiation is required.
보고된 수많은 광촉매 중, 층상 형태를 갖는 금속 미포함 고분자 반도체인 흑연질화탄소(g-C3N4)는 수분해, 환경유기오염물질의 광분해, 유기합성 및 CO2 감소 등 많은 분야에서 많은 관심을 받고 있다. g-C3N4는 가시광선 응답성, 극도의 안정성, 무독성, 손쉬운 제조, 저비용 제조 등 뛰어난 특성을 가지고 있기 때문이다. 그럼에도 불구하고, 기존의 벌크 g-C3N4는 광유도 전하의 높은 재결합율, 작은 비표면적 및 불충분한 태양광 흡수로 인해 일반적으로 불리한 광촉매 효율에 의해 적용이 제한되었다. 나노구조 설계, 원소 및 분자 도핑, 초분자 사전조직화, 계면 공학, 염료 감작을 포함한 다양한 수정 접근법을 통해 상기와 같은 단점을 보완하고 광촉매 성능을 향상시키기 위해 연구되었다. Among numerous reported photocatalysts, graphitic carbon nitride (gC 3 N 4 ), a layered metal-free polymeric semiconductor, has attracted much attention in many fields such as water decomposition, photolysis of environmental organic pollutants, organic synthesis, and CO 2 reduction. . This is because gC 3 N 4 has excellent properties such as visible light responsiveness, extreme stability, non-toxicity, easy manufacturing, and low-cost manufacturing. Nonetheless, conventional bulk gC 3 N 4 has generally been limited by unfavorable photocatalytic efficiency due to high recombination rate of photoinduced charge, small specific surface area and insufficient solar absorption. Various modification approaches including nanostructure design, elemental and molecular doping, supramolecular preorganization, interface engineering, and dye sensitization have been studied to compensate for the above disadvantages and improve photocatalytic performance.
그러나 폐수에서 발생하는 유기 오염 물질을 정화하기 위한 고성능 가시광 반응성 광촉매를 구축하는 것은 최근 몇 년 동안 여전히 큰 과제였다. g-C3N4의 가시광선 광촉매 효과를 높일 수 있는 중요한 전략은 구조에서 다공성을 확보하는 것이다. 다공성을 도입하면 표면적, 도달 가능한 채널 및 활성 부위가 확대되어 광 생성 전하 분리, 분자 질량 전달 및 표면 반응이 향상된다. However, building high-performance visible light-responsive photocatalysts to purify organic pollutants from wastewater remains a major challenge in recent years. An important strategy to enhance the visible light photocatalytic effect of g-C3N4 is to secure porosity in the structure. Introducing porosity enlarges the surface area, reachable channels and active sites, enhancing photogenerated charge separation, molecular mass transfer and surface reactions.
또한, 최근 연구에 따르면 g-C3N4의 격자 구조에 질소 결함을 주입하면 비스페놀 A 분해, 수소 발생 및 CO2 감소의 다양한 적용에서 광촉매 활성이 현저하게 강화될 수 있다고 보고된바 있다. 이는 주로 결함 사이트가 광생성 전자를 포획하고 전하 캐리어 분리를 촉진하는 경향이 있기 때문이다. In addition, recent studies have reported that injecting nitrogen vacancies into the lattice structure of gC 3 N 4 can significantly enhance the photocatalytic activity in various applications of bisphenol A decomposition, hydrogen generation and CO 2 reduction. This is mainly because defect sites tend to trap photogenerated electrons and promote charge carrier separation.
본 출원은 촉매의 활성 부위, 광 흡수 효율 및 전하 분리 능력을 동시에 향상시키기 위해 질소 결함이 있는 나노구조의 다공성 흑연질화탄소의 제조 방법에 관한 것이다. The present application relates to a method for preparing nanostructured porous graphitic nitride having nitrogen defects in order to simultaneously improve the active site, light absorption efficiency and charge separation ability of a catalyst.
본 출원의 일 측면은 흑연질화탄소의 제조 방법에 관한 것이다.One aspect of the present application relates to a method for producing graphitic carbon nitride.
일 예시에서, 상기 제조 방법은 g-C3N4 및 SiO2 복합체를 형성하는 단계; 및 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함할 수 있다.In one example, the manufacturing method may include forming a gC 3 N 4 and SiO 2 complex; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
일 예시에서, SiO2 템플릿을 제거하는 단계 후, SiO2 템플릿이 제거된 잔여물을 원심분리하는 단계; pH가 7이 될 때까지 증류수로 세척하는 단계; 및 오븐에서 60 내지 80 ℃에서 건조하는 단계를 추가로 포함할 수 있다.In one example, after removing the SiO 2 template, centrifuging the residue from which the SiO 2 template is removed; Washing with distilled water until the pH is 7; and drying in an oven at 60 to 80 °C.
일 예시에서, 상기 제조 방법은 콜로이드 SiO2 분산액을 건조한 후 분쇄하여 SiO2 클러스터 템플릿을 제조하는 단계; SiO2 템플릿과 멜라민을 혼합하여 혼합물을 제조하는 단계; 혼합물을 가열하여, g-C3N4 및 SiO2 복합체를 형성하는 단계; 및 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함할 수 있다.In one example, the manufacturing method comprises preparing a SiO 2 cluster template by drying and pulverizing the colloidal SiO 2 dispersion ; Preparing a mixture by mixing the SiO 2 template and melamine; heating the mixture to form a gC 3 N 4 and SiO 2 composite; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
일 예시에서, 콜로이드 SiO2 분산액을 80 내지 120 ℃의 오븐에서 건조할 수 있다.In one example, the colloidal SiO 2 dispersion may be dried in an oven at 80 to 120 °C.
일 예시에서, 콜로이드 SiO2 분산액을 10 내지 14 시간 동안 건조할 수 있다.In one example, the colloidal SiO 2 dispersion may be dried for 10 to 14 hours.
일 예시에서, SiO2 템플릿과 멜라민을 1 : 1 내지 1.5의 중량비로 혼합할 수 있다.In one example, the SiO 2 template and melamine may be mixed in a weight ratio of 1:1 to 1.5.
일 예시에서, 혼합물을 550 ℃까지 가열하고 2 내지 4 시간 유지하여, g-C3N4 및 SiO2 복합체를 형성할 수 있다.In one example, the mixture may be heated to 550 °C and held for 2 to 4 hours to form a gC 3 N 4 and SiO 2 composite.
일 예시에서, 불화 수소(HF) 용액을 첨가하여 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거할 수 있다.In one example, a hydrogen fluoride (HF) solution may be added to remove the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
일 예시에서, 상기 제조 방법은 SiO2 미소구체를 준비하는 단계; SiO2 미소구체에 용융 시안아미드(cyanamide)를 혼합하여 혼합물을 제조하는 단계; 혼합물을 가열하여, g-C3N4 및 SiO2 복합체를 형성하는 단계; 및 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함할 수 있다.In one example, the manufacturing method includes preparing SiO 2 microspheres; preparing a mixture by mixing molten cyanamide with SiO 2 microspheres; heating the mixture to form a gC 3 N 4 and SiO 2 composite; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
일 예시에서, 시안아미드 및 실리카 미소구체의 중량비는 1 : 0.1 내지 2.5일 수 있다.In one example, the weight ratio of cyanamide and silica microspheres may be 1:0.1 to 2.5.
일 예시에서, 실리카 미소구체의 평균직경은 200 내지 400 nm일 수 있다.In one example, the average diameter of the silica microspheres may be 200 to 400 nm.
일 예시에서, 혼합물을 70 내지 90℃에서 20 내지 40분 동안 혼합하고, 냉각 후 다시 500 내지 600 ℃에서 가열하여 g-C3N4 및 SiO2 복합체를 형성할 수 있다.In one example, the mixture may be mixed at 70 to 90 °C for 20 to 40 minutes, cooled, and then heated again at 500 to 600 °C to form a gC 3 N 4 and SiO 2 composite.
일 예시에서, 이불화 수소 암모늄(ammonium hydrogen difluoride) 용액을 첨가하여 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거할 수 있다.In one example, the SiO 2 template may be removed from the gC 3 N 4 and SiO 2 complex by adding an ammonium hydrogen difluoride solution.
본 출원의 다른 측면은 이러한 제조 방법에 의해 제조된 흑연질화탄소에 관한 것이다.Another aspect of the present application relates to graphitic carbon nitride produced by this production method.
일 예시에서, 기공의 평균 볼륨은 0.2 내지 0.3 cm3g-1일 수 있다.In one example, the average volume of pores may be 0.2 to 0.3 cm 3 g -1 .
일 예시에서, 기공의 평균 직경은 10 내지 20 nm일 수 있다.In one example, the average diameter of the pores may be 10 to 20 nm.
일 예시에서, BET 비표면적은 30 내지 70 m2g-1일 수 있다.In one example, the BET specific surface area may be 30 to 70 m 2 g -1 .
본 출원의 다른 측면은 이러한 흑연질화탄소를 포함하는 가시광선 광촉매에 관한 것이다.Another aspect of the present application relates to a visible ray photocatalyst including such graphitic carbon nitride.
본 출원의 일 실시예에 따르면, 유기오염물 제거를 위한 고성능 그래파이트 카본질화 광촉매의 제조기술을 제공할 수 있다. According to one embodiment of the present application, it is possible to provide a manufacturing technology of a high-performance graphite carbonitride photocatalyst for removing organic contaminants.
본 출원의 일 실시예에 따르면, 하드 템플레이트 기법 (실리카 나노클라스트)을 이용한광촉매의 Morphology/다공성/표면적 조절과 성능향상 기술을 제공할 수 있다.According to an embodiment of the present application, it is possible to provide a technology for controlling morphology/porosity/surface area and improving performance of a photocatalyst using a hard template technique (silica nanoclast).
본 출원의 일 실시예에 따르면, 하드 템플레이트 기법 (실리카 마이크로 스피어)에 Inverse Opal 구조를 만들어 원하는 일정한 형태의 유기성 나노 광촉매 디자인을 제공할 수 있다.According to one embodiment of the present application, it is possible to provide an organic nano photocatalyst design of a desired shape by creating an inverse opal structure in a hard template technique (silica microspheres).
본 출원의 일 실시예에 따르면, 다양한 난분해성 유기오염물 (RhB, MB, TC 등)의 효율적 처리기법을 제공할 수 있다.According to one embodiment of the present application, it is possible to provide an efficient treatment technique for various recalcitrant organic contaminants (RhB, MB, TC, etc.).
본 출원의 일 실시예에 따르면, 광분해 메카니즘 정립 및 독성감소 효과를 제공할 수 있다.According to one embodiment of the present application, it is possible to provide an effect of establishing a photolysis mechanism and reducing toxicity.
도 1은 하드 템플렛 방법을 이용한 흑연질화탄소의 합성 방법을 설명하기 위한 모식도이다. 1 is a schematic diagram for explaining a method for synthesizing graphitized carbon nitride using a hard template method.
도 2a는 SiO2 클러스터의 SEM 이미지이고, 도 2b는 NC MCN의 SEM 이미지이며, 도 2c는 벌크 CN의 SEM 이미지이고, 도 2d 내지 도 2h는 NC MCN의 TEM 이미지이다. Fig. 2a is a SEM image of SiO2 cluster, Fig. 2b is a SEM image of NC MCN, Fig. 2c is an SEM image of bulk CN, and Figs. 2d to 2h are TEM images of NC MCN.
도 3a는 SiO2 미소구체의 SEM 이미지이고, 도 3b는 IO CN 1:0.5의 SEM 이미지이며, 도 2c는 IO CN 1:1의 SEM 이미지이며, 도 2d 및 도 2e는 IO CN 1:2의 SEM 이미지이고, 도 2f는 IO CN 1:2의 TEM 이미지이다.Figure 3a is a SEM image of SiO2 microspheres, Figure 3b is a SEM image of IO CN 1:0.5, Figure 2c is a SEM image of IO CN 1:1, Figures 2d and 2e are SEM images of IO CN 1:2 2f is a TEM image of IO CN 1:2.
도 4a는 NC MCN과 벌크 CN의 N2 흡착/탈착 등온선을 도시하고, 도 4b는 해당 기공 크기 분포 곡선을 도시한다.Figure 4a shows the N2 adsorption/desorption isotherms of NC MCN and bulk CN, and Figure 4b shows the corresponding pore size distribution curves.
도 5a는 IO CN과 벌크 CN의 N2 흡착/탈착 등온선을 도시하고, 도 5b는 해당 기공 크기 분포 곡선을 도시한다.Figure 5a shows the N2 adsorption/desorption isotherms of IO CN and bulk CN, and Figure 5b shows the corresponding pore size distribution curves.
도 6a은 로다민 B (RhB) 분해의 광촉매 분해 곡선이고, 도 6b는 테트라사이클린(TC) 분해의 광촉매 분해 곡선이며, 도 6c는 로다민에 대한 광촉매 분해의 유사 1차 동역학 곡선이고, 도 6d는 테트라사이클린에 대한 광촉매 분해의 유사 1차 동역학 곡선이다.Figure 6a is a photocatalytic degradation curve of rhodamine B (RhB) degradation, Figure 6b is a photocatalytic degradation curve of tetracycline (TC) degradation, Figure 6c is a pseudo first-order kinetic curve of photocatalytic degradation for rhodamine, Figure 6d is a pseudo first-order kinetic curve of photocatalytic degradation for tetracycline.
도 7은 NC MCN의 MB 분해 UV-vis 스펙트럼에 대한 그래프이다.7 is a graph of MB decomposition UV-vis spectrum of NC MCN.
도 8은 NC MCN의 RhB와 MB 혼합물의 분해 UV-vis 스펙트럼(RhB 및 MB 피크)에 대한 그래프이다. 8 is a graph of the decomposition UV-vis spectrum (RhB and MB peaks) of a mixture of RhB and MB of NC MCN.
도 9는 NC MCN의 RhB와 MB 혼합물의 분해 UV-vis 스펙트럼(전체 피크)에 대한 그래프이다.9 is a graph of the decomposition UV-vis spectrum (all peaks) of a mixture of RhB and MB of NC MCN.
도 10a는 IO CN 1:2 존재하에서 MB의 UV-Vis 흡수 스펙트럼이고, 도 10b는 준비된 광촉매 존재하에서 MB 분해에 대한 광촉매 분해 곡선이다.10a is a UV-Vis absorption spectrum of MB in the presence of IOCN 1:2, and FIG. 10b is a photocatalytic decomposition curve for MB decomposition in the presence of a prepared photocatalyst.
도 11a는 IO CN 1:2 존재하에서 RhB의 UV-Vis 흡수 스펙트럼이고, 도 11b는 준비된 광촉매 존재하에서 RhB 분해에 대한 광촉매 분해 곡선이다.11a is a UV-Vis absorption spectrum of RhB in the presence of IOCN 1:2, and FIG. 11b is a photocatalytic decomposition curve for RhB decomposition in the presence of a prepared photocatalyst.
도 12는 8 사이클 내의 TC 분해에서 NC MCN의 광촉매 안정성을 나타내는 그래프이다.12 is a graph showing the photocatalytic stability of NC MCN in TC decomposition within 8 cycles.
도 13은 미사용한 NC MCN과 사용한 NC MCN의 SEM 이미지이다.13 is a SEM image of an unused NC MCN and a used NC MCN.
도 14는 NC MCN의 TC 및 RhB 광촉매 분해의 개략도이다.14 is a schematic diagram of TC and RhB photocatalytic degradation of NC MCN.
도 15는 TC의 광분해 과정에서 제안된 중간 생산 경로를 나타낸다.15 shows the intermediate production pathway proposed in the photolysis process of TC.
도 16은 NC MCN을 사용하여 광촉매 분해로 생성된 TC 중간체의 독성 평가 결과로서 (a) 급성 독성 LD50; (b) 생물축적계수; (c) 발달 독성 (d) 변이원성에 대한 그래프이다.Figure 16 shows the toxicity evaluation results of TC intermediates produced by photocatalytic degradation using NC MCN (a) acute toxicity LD50; (b) bioaccumulation coefficient; (c) It is a graph for developmental toxicity (d) mutagenicity.
본 출원에서 사용한 용어는 단지 특정한 실시예를 설명하기 위해 사용된 것으로, 본 발명을 한정하려는 의도가 아니다. 단수의 표현은 문맥상 명백하게 다르게 뜻하지 않는 한, 복수의 표현을 포함한다. 본 출원에서, "포함하다" 또는 "가지다" 등의 용어는 명세서 상에 기재된 특징, 구성요소 등이 존재함을 지정하려는 것이지, 하나 또는 그 이상의 다른 특징들이나 구성요소 등이 존재하지 않거나 부가될 수 없음을 의미하는 것은 아니다.Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "include" or "have" are intended to designate that the features, components, etc. described in the specification exist, but one or more other features or components may not exist or be added. That doesn't mean there aren't any.
다르게 정의되지 않는 한, 기술적이거나 과학적인 용어를 포함해서 여기서 사용되는 모든 용어들은 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자에 의해 일반적으로 이해되는 것과 동일한 의미를 가지고 있다. 일반적으로 사용되는 사전에 정의되어 있는 것과 같은 용어들은 관련 기술의 문맥상 가지는 의미와 일치하는 의미를 가지는 것으로 해석되어야 하며, 본 출원에서 명백하게 정의하지 않는 한, 이상적이거나 과도하게 형식적인 의미로 해석되지 않는다.Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, it should not be interpreted in an ideal or excessively formal meaning. don't
본 출원에서 용어 "나노"는 나노 미터(nm) 단위의 크기를 의미할 수 있고, 예를 들어, 1 내지 1,000 nm의 크기를 의미할 수 있으나, 이에 제한되는 것은 아니다. 또한, 본 명세서에서 용어 "나노 입자"는 나노 미터(nm) 단위의 평균 입경을 갖는 입자를 의미할 수 있고, 예를 들어, 1 내지 1,000 nm의 평균입경을 갖는 입자를 의미할 수 있으나, 이에 제한되는 것은 아니다.In the present application, the term "nano" may refer to a size in a nanometer (nm) unit, for example, from 1 to 1,000 nm, but is not limited thereto. In addition, the term "nanoparticle" in this specification may mean a particle having an average particle diameter in nanometer (nm) units, for example, may mean a particle having an average particle diameter of 1 to 1,000 nm, but It is not limited.
본 출원의 일 측면은 흑연질화탄소의 제조 방법에 관한 것이다.One aspect of the present application relates to a method for producing graphitic carbon nitride.
일 예시에서, 상기 제조 방법은 g-C3N4 및 SiO2 복합체를 형성하는 단계; 및 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함할 수 있다.In one example, the manufacturing method may include forming a gC 3 N 4 and SiO 2 complex; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
일 예시에서, SiO2 템플릿을 제거하는 단계 후, SiO2 템플릿이 제거된 잔여물을 원심분리하는 단계; pH가 7이 될 때까지 증류수로 세척하는 단계; 및 오븐에서 60 내지 80 ℃에서 건조하는 단계를 추가로 포함할 수 있다.In one example, after removing the SiO 2 template, centrifuging the residue from which the SiO 2 template is removed; Washing with distilled water until the pH is 7; and drying in an oven at 60 to 80 °C.
일 예시에서, 상기 제조 방법은 콜로이드 SiO2 분산액을 건조한 후 분쇄하여 SiO2 클러스터 템플릿을 제조하는 단계; SiO2 템플릿과 멜라민을 혼합하여 혼합물을 제조하는 단계; 혼합물을 가열하여, g-C3N4 및 SiO2 복합체를 형성하는 단계; 및 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함할 수 있다.In one example, the manufacturing method comprises preparing a SiO 2 cluster template by drying and pulverizing the colloidal SiO 2 dispersion ; Preparing a mixture by mixing the SiO 2 template and melamine; heating the mixture to form a gC 3 N 4 and SiO 2 complex; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
일 예시에서, 콜로이드 SiO2 분산액을 80 내지 120 ℃의 오븐에서 건조할 수 있다. 일 예시에서, 콜로이드 SiO2 분산액을 10 내지 14 시간 동안 건조할 수 있다. 일 예시에서, SiO2 템플릿과 멜라민을 1 : 1 내지 1.5의 중량비로 혼합할 수 있다. 일 예시에서, 혼합물을 550 ℃까지 가열하고 2 내지 4 시간 유지하여, g-C3N4 및 SiO2 복합체를 형성할 수 있다. 일 예시에서, 불화 수소(HF) 용액을 첨가하여 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거할 수 있다.In one example, the colloidal SiO 2 dispersion may be dried in an oven at 80 to 120 °C. In one example, the colloidal SiO 2 dispersion may be dried for 10 to 14 hours. In one example, the SiO 2 template and melamine may be mixed in a weight ratio of 1:1 to 1.5. In one example, the mixture may be heated to 550 °C and held for 2 to 4 hours to form a gC 3 N 4 and SiO 2 composite. In one example, a hydrogen fluoride (HF) solution may be added to remove the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
구체적으로, 메조포러스 g-C3N4를 제조하기 위해, 콜로이드 실리카 분산액(12 nm, Ludox HS-40, 40% wt.% 수중 현탁액)을 100 ℃의 오븐에서 12시간 동안 건조한 다음 모르타르에서 분쇄한다. 얻어진 SiO2 클러스터 템플릿(1.5g)을 멜라민(1.5g)과 완전히 혼합하고 도가니에 옮긴다. 그 후, 혼합물을 공기 중에서 4시간 동안 실온으로부터 550℃까지 가열하고, 이 온도에서 3시간 동안 유지한다. 생성된 노란색 g-C3N4/SiO2 하이브리드를 40mL의 10% HF 용액에 24시간 동안 첨가하여 실리카 템플릿을 제거한다. 그런 다음 현탁액을 원심분리하고 pH가 7이 될 때까지 증류수로 여러 번 세척한 다음 최종적으로 오븐에서 70 ℃에서 건조한다. 본 출원에서는 생성된 촉매를 NC MCN으로 지칭한다. 참고 샘플로 1.5g의 멜라민을 이전과 동일한 열처리로 소성하여 벌크 g-C3N4를 합성하고 벌크 CN이라고 지칭한다.Specifically, to prepare mesoporous gC 3 N 4 , a colloidal silica dispersion (12 nm, Ludox HS-40, 40% wt.% aqueous suspension) was dried in an oven at 100° C. for 12 hours and then ground in a mortar. The resulting SiO 2 cluster template (1.5 g) was thoroughly mixed with melamine (1.5 g) and transferred to a crucible. The mixture is then heated from room temperature to 550° C. in air for 4 hours and held at this temperature for 3 hours. The resulting yellow gC 3 N 4 /SiO 2 hybrid was added to 40 mL of 10% HF solution for 24 hours to remove the silica template. Then, the suspension was centrifuged, washed several times with distilled water until the pH reached 7, and finally dried in an oven at 70 °C. In this application, the resulting catalyst is referred to as NC MCN. As a reference sample, 1.5 g of melamine was calcined with the same heat treatment as before to synthesize bulk gC 3 N 4 , which is referred to as bulk CN.
또한, 상기 제조 방법은 SiO2 미소구체를 준비하는 단계; SiO2 미소구체에 용융 시안아미드(cyanamide)를 혼합하여 혼합물을 제조하는 단계; 혼합물을 가열하여, g-C3N4 및 SiO2 복합체를 형성하는 단계; 및 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함할 수 있다.In addition, the manufacturing method may include preparing SiO 2 microspheres; preparing a mixture by mixing molten cyanamide with SiO 2 microspheres; heating the mixture to form a gC 3 N 4 and SiO 2 composite; and removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
일 예시에서, 시안아미드 및 실리카 미소구체의 중량비는 1 : 0.5 내지 2.5일 수 있다. 일 예시에서, 실리카 미소구체의 평균직경은 200 내지 400 nm일 수 있다. 일 예시에서, 혼합물을 70 내지 90℃에서 20 내지 40분 동안 혼합하고, 냉각 후 다시 500 내지 600 ℃에서 가열하여 g-C3N4 및 SiO2 복합체를 형성할 수 있다. 일 예시에서, 이불화 수소 암모늄(ammonium hydrogen difluoride) 용액을 첨가하여 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거할 수 있다.In one example, the weight ratio of cyanamide and silica microspheres may be 1:0.5 to 2.5. In one example, the average diameter of the silica microspheres may be 200 to 400 nm. In one example, the mixture may be mixed at 70 to 90 °C for 20 to 40 minutes, cooled, and then heated again at 500 to 600 °C to form a gC 3 N 4 and SiO 2 composite. In one example, the SiO 2 template may be removed from the gC 3 N 4 and SiO 2 complex by adding an ammonium hydrogen difluoride solution.
구체적으로 직경이 약 300 nm인 균일하게 분산된 실리카 미소구체는 잘 알려진 Stober 방법을 기반으로 합성된다. 구체적으로, 용액 A는 154ml의 암모니아수, 304ml의 에탄올, 370ml의 탈이온수를 교반기에서 10분간 혼합하여 제조한다. 683ml의 에탄올 및 67ml의 테트라에톡시실란(TEOS)을 함유하는 용액 B를 약 1분 내에 용액 A에 첨가하고, 그 동안 용액을 강력하게 교반한다(800r/min). 그 후, 용액을 자기 교반(400 r/min) 하에 16시간 동안 유지하여, 실리카 입자의 성장하도록 한다. 그런 다음 흰색 침전물을 원심분리(11000rpm)로 수집하고, 물과 에탄올로 3회 세척하고 에탄올 100ml와 혼합하고 15분 동안 초음파 처리한 다음 100°C의 오븐에서 건조시킨다. 마지막으로, 제조된 백색 고체를 막자사발에서 분쇄하고 4시간 동안 실온에서 550℃로 공기 중에서 가열하고 이 온도에서 6시간 동안 유지하여 단분산된 SiO2 미소구체를 수득한다.Specifically, uniformly dispersed silica microspheres with a diameter of about 300 nm were synthesized based on the well-known Stober method. Specifically, solution A was prepared by mixing 154 ml of ammonia water, 304 ml of ethanol, and 370 ml of deionized water in a stirrer for 10 minutes. Solution B containing 683 ml of ethanol and 67 ml of tetraethoxysilane (TEOS) is added to solution A in about 1 minute, during which the solution is vigorously stirred (800 r/min). Then, the solution is kept under magnetic stirring (400 r/min) for 16 hours to allow growth of silica particles. Then, the white precipitate was collected by centrifugation (11000 rpm), washed three times with water and ethanol, mixed with 100 ml of ethanol, sonicated for 15 min, and dried in an oven at 100 °C. Finally, the prepared white solid is ground in a mortar and heated in air from room temperature to 550° C. for 4 hours and held at this temperature for 6 hours to obtain monodispersed SiO 2 microspheres.
도 1은 하드 템플렛 방법을 이용한 흑연질화탄소의 합성 방법을 설명하기 위한 모식도이다. 1 is a schematic diagram for explaining a method for synthesizing graphitized carbon nitride using a hard template method.
시안아미드(cyanamide)는 g-C3N4의 역오팔(inverse opal) 구조를 합성하기 위한 전구체로 사용된다. 먼저 세라믹 판에 시안아미드 1.5g을 넣고, 80 ℃의 온도에서 녹을 때까지 교반하여 녹인다. 그 다음, 일정 양의 SiO2 미소구체를 용융된 시안아미드에 점진적으로 첨가한다. 그런 다음 혼합물을 동일한 온도(80℃)에서 약 30분 동안 계속 혼합한다. 그 후, 혼합물을 냉각시키고, 분쇄하고, 하소용 도가니로 옮긴다. 도가니는 2.2 ℃/min의 램핑 속도로 2시간 동안 550 ℃의 공기 중 머플로에서 가열된다. g-C3N4/SiO2 복합체의 생성된 노란색 샘플을 40ml의 4M 이불화수소 암모늄과 48시간 동안 혼합하여 SiO2 하드 템플릿을 완전히 제거한다. 그런 다음 현탁액을 PH가 7이 될 때까지 증류수로 여러 번 세척한 다음 80 ℃의 오븐에서 24시간 동안 건조시킨다. 얻어진 촉매는 IO CN x:y로 지칭하고, 여기서 x 및 y는 시안아미드:실리카 미소구체의 질량비이며, 이는 IO CN 1:0.5(IO CN1), IO CN 1:1(IO CN2), IO CN 1:2(IO CN3)이다. 본 출원의 제어 촉매로서 벌크 CN으로 대표되는 동일한 열처리 방법으로 실리카 입자 없이 cyanamide를 소성하여 벌크 g-C3N4를 합성한다. Cyanamide is used as a precursor to synthesize the inverse opal structure of gC 3 N 4 . First, 1.5 g of cyanamide was put into a ceramic plate, and dissolved by stirring at a temperature of 80 °C until melted. Then, a certain amount of SiO 2 microspheres are gradually added to the molten cyanamide. The mixture is then continuously mixed for about 30 minutes at the same temperature (80° C.). The mixture is then cooled, ground and transferred to a calcining crucible. The crucible is heated in a muffle furnace in air at 550 °C for 2 hours at a ramping rate of 2.2 °C/min. The resulting yellow sample of the gC 3 N 4 /SiO 2 complex was mixed with 40 ml of 4M ammonium bifluoride for 48 hours to completely remove the SiO 2 hard template. Then, the suspension was washed several times with distilled water until the pH reached 7 and then dried in an oven at 80 °C for 24 hours. The obtained catalyst is referred to as IO CN x:y, where x and y are the mass ratios of cyanamide:silica microspheres, which are IO CN 1:0.5 (IO CN1), IO CN 1:1 (IO CN2), IO CN 1:2 (IO CN3). As a control catalyst of the present application, bulk gC 3 N 4 is synthesized by calcining cyanamide without silica particles using the same heat treatment method represented by bulk CN.
본 출원의 다른 측면은 이러한 제조 방법에 의해 제조된 흑연질화탄소에 관한 것이다. 일 예시에서, 기공의 평균 볼륨은 0.2 내지 0.3 cm3g-1일 수 있다. 일 예시에서, 기공의 평균 직경은 10 내지 20 nm일 수 있다. 일 예시에서, BET 비표면적은 30 내지 70 m2g-1일 수 있다.Another aspect of the present application relates to graphitic carbon nitride produced by this production method. In one example, the average volume of pores may be 0.2 to 0.3 cm 3 g -1 . In one example, the average diameter of the pores may be 10 to 20 nm. In one example, the BET specific surface area may be 30 to 70 m 2 g -1 .
본 출원의 다른 측면은 이러한 흑연질화탄소를 포함하는 가시광선 광촉매에 관한 것이다.Another aspect of the present application relates to a visible ray photocatalyst including such graphitic carbon nitride.
이하, 실험예를 통하여 본 출원을 보다 상세히 설명한다.Hereinafter, the present application will be described in more detail through experimental examples.
[SEM 및 TEM 측정][SEM and TEM measurements]
메조포러스 흑연질화탄소 나노클러스터Mesoporous graphitic carbon nitride nanoclusters
실리카 클러스터 및 합성 물질의 형태 및 미세 구조를 탐색하기 위해 SEM 및 TEM을 이용하였다. 도 2a는 SiO2 클러스터의 SEM 이미지이고, 도 2b는 NC MCN의 SEM 이미지이며, 도 2c는 벌크 CN의 SEM 이미지이고, 도 2d 내지 도 2h는 NC MCN의 TEM 이미지이다. SEM and TEM were used to explore the morphology and microstructure of silica clusters and synthetic materials. 2a is a SEM image of SiO 2 cluster, FIG. 2b is a SEM image of NC MCN, FIG. 2c is an SEM image of bulk CN, and FIGS. 2d to 2h are TEM images of NC MCN.
도 2a는 건조 후 SiO2 클러스터의 SEM 이미지이다. 도 2a에 도시한 바와 같이, 작은 실리카 나노입자의 점착 및 응집을 통해 실리카 클러스터의 형성을 확인할 수 있다. SiO2 클러스터와 멜라민을 혼합한 후, 소성 과정에서 g-C3N4 평면의 성장은 실리카 클러스터의 모양에 따라 제한되고 제어된다. 2a is a SEM image of SiO 2 clusters after drying. As shown in FIG. 2A, formation of silica clusters can be confirmed through adhesion and aggregation of small silica nanoparticles. After mixing the SiO 2 clusters with melamine, the growth of gC 3 N 4 planes during firing is limited and controlled according to the shape of the silica clusters.
도 2b는 NC MCN의 얻어진 형태를 나타낸다. 반면, 실리카 클러스터를 사용하지 않고 합성된 g-C3N4는 도 2c에서 매우 적층된 형태를 나타냄을 알 수 있다. Figure 2b shows the obtained morphology of NC MCN. On the other hand, it can be seen that gC 3 N 4 synthesized without using silica clusters shows a highly layered structure in FIG. 2c.
도 2d 내지 2f를 참조하면, NC MCN의 내부 구조와 형태를 추가로 확인할 수 있으며, 이는 작은 클러스터와 메조포러스 아키텍처의 구성을 확인할 수 있다.Referring to FIGS. 2D to 2F , the internal structure and shape of the NC MCN can be further confirmed, which confirms the configuration of small clusters and mesoporous architecture.
도 2g 및 2h는 0.33nm의 면간 간격을 갖는 NC MCN의 HRTEM 가장자리(fringe)를 나타낸다.2g and 2h show the HRTEM fringe of NC MCN with an interplanar spacing of 0.33 nm.
역오팔 흑연질화탄소Inverse Opal Graphite Carbon Nitride
추가로, 실리카 클러스터 및 합성 물질의 형태 및 미세 구조를 탐색하기 위해 SEM 및 TEM을 이용하였다. Additionally, SEM and TEM were used to explore the morphology and microstructure of silica clusters and synthetic materials.
본 출원에서 시안아미드와 실리카의 함량은 1 : 0.1 내지 2.5 이며, 바람직하게는 1:0.5, 1:1, 및 1:2 이며 보다 바람직하게는 1:2이다.In the present application, the content of cyanamide and silica is 1:0.1 to 2.5, preferably 1:0.5, 1:1, and 1:2, more preferably 1:2.
도 3a는 SiO2 미소구체의 SEM 이미지이고, 도 3b는 IO CN 1:0.5의 SEM 이미지이며, 도 2c는 IO CN 1:1의 SEM 이미지이며, 도 2d 및 도 2e는 IO CN 1:2의 SEM 이미지이고, 도 2f는 IO CN 1:2의 TEM 이미지이다.3a is a SEM image of SiO 2 microspheres, FIG. 3b is a SEM image of IO CN 1:0.5, FIG. 2c is a SEM image of IO CN 1:1, and FIGS. 2d and 2e are SEM images of IO CN 1:2 SEM image, and Fig. 2f is a TEM image of IO CN 1:2.
도 3a를 참조하면, 300 nm의 평균 크기에서 SiO2 미소구체의 SEM 이미지는 균일한 구형의 구성을 확인할 수 있다. 도 3b는 cyanamide/SiO2 질량비 1/0.5를 사용하여 합성한 inverse opal g-C3N4의 SEM 이미지이다. 도 3c는 1/1의 시안아미드/SiO2 질량비에 대한 것이고, 도 3d 및 3e는 훨씬 더 높은 균일한 구조를 나타내는 1/2의 시안아미드/SiO2 질량비에 대한 SEM 이미지이다. 또한 도 3f는 균일한 다공성을 갖는 바람직한 샘플로 간주되는 IO CN3의 TEM 이미지이다.Referring to FIG. 3a , the SEM image of SiO 2 microspheres at an average size of 300 nm confirms a uniform spherical configuration. 3b is a SEM image of inverse opal gC 3 N 4 synthesized using a cyanamide/SiO 2 mass ratio of 1/0.5. 3c is for a cyanamide/SiO 2 mass ratio of 1/1, and FIGS. 3d and 3e are SEM images for a cyanamide/SiO 2 mass ratio of 1/2 showing a much higher uniform structure. 3f is a TEM image of IO CN3, which is considered to be a desirable sample with uniform porosity.
[비표면적(BET)][Specific surface area (BET)]
메조포러스 흑연질화탄소 나노클러스터Mesoporous graphitic carbon nitride nanoclusters
촉매의 표면 특성과 다공성을 추가로 조사하기 위해 질소 흡탈착 측정을 수행하였다. Nitrogen adsorption and desorption measurements were performed to further investigate the surface properties and porosity of the catalyst.
도 4a는 NC MCN과 벌크 CN의 N2 흡착/탈착 등온선을 도시하고, 도 4b는 해당 기공 크기 분포 곡선을 도시한다.Figure 4a shows the N 2 adsorption/desorption isotherms of NC MCN and bulk CN, and Figure 4b shows the corresponding pore size distribution curves.
얻은 두 촉매의 플롯은 IUPAC(International Union of Pure and Applied Chemistry) 분류를 기반으로 0.4-0.95P/P0 범위의 H3 히스테리시스 루프가 있는 전형적인 IV형 등온선을 나타내어 메조포러스 구조의 존재를 확인하였다. The obtained plots of the two catalysts showed typical type IV isotherms with H3 hysteresis loops in the range of 0.4–0.95 P/P0 based on the International Union of Pure and Applied Chemistry (IUPAC) classification, confirming the existence of a mesoporous structure.
BJH 기공 크기 분포는 NC MCN이 벌크 CN과 비교하여 2에서 20nm 범위에서 매우 풍부한 중간 기공을 보유하고 있음을 확인할 수 있었다. 또한, 샘플에는 20nm보다 큰 기공이 80nm까지 존재하는데, 이는 다양한 크기의 실리카 클러스터의 역복사 때문이다. The BJH pore size distribution confirmed that NC MCN has very abundant mesopores in the range of 2 to 20 nm compared to bulk CN. In addition, pores larger than 20 nm exist up to 80 nm in the sample, which is due to the reverse radiation of silica clusters of various sizes.
샘플의 기공 부피, 기공 직경 및 BET 비표면적을 표 1에 나타낸다.The pore volume, pore diameter and BET specific surface area of the samples are shown in Table 1.
Pore volume (cm3g-1)Pore volume (cm 3 g -1 ) Pore diameter (nm)Pore diameter (nm) BET surface area (m2g-1)BET surface area (m 2 g -1 )
NC MCNNC MCN 0.2260.226 17.6617.66 51.3451.34
벌크 CNbulk CN 0.1260.126 23.6323.63 21.4921.49
표 1에 나타낸 바와 같이, 일관되게 NC MCN은 51.34 m2g-1의 비표면적 및 0.226 cm3g-1의 기공 부피를 나타내었고, 이는 벌크 CN(21.49 m2g-1, 0.126 cm3g-1)의 값보다 높았으며, 실리카 클러스터를 단단한 주형으로 사용하면 표면적이 증가하고 기공 부피가 확대된 메조포러스 구조를 크게 생성할 수 있음을 뒷받침한다.As shown in Table 1, NC MCN consistently exhibited a specific surface area of 51.34 m 2 g -1 and a pore volume of 0.226 cm 3 g -1 , which was comparable to bulk CN (21.49 m 2 g -1 , 0.126 cm 3 g -1 ), supporting the fact that the use of silica clusters as a hard template can generate a large mesoporous structure with increased surface area and enlarged pore volume.
역오팔 흑연질화탄소Inverse Opal Graphite Carbon Nitride
도 5a는 IO CN과 벌크 CN의 N2 흡착/탈착 등온선을 도시하고, 도 5b는 해당 기공 크기 분포 곡선을 도시한다.Figure 5a shows the N 2 adsorption/desorption isotherms of IO CN and bulk CN, and Figure 5b shows the corresponding pore size distribution curves.
두 촉매의 플롯은 IUPAC(International Union of Pure and Applied Chemistry) 분류를 기반으로 0.4-0.95P/P0 범위의 H3 히스테리시스 루프가 있는 전형적인 IV형 등온선을 나타내어 메조포러스 구조의 존재를 확인할 수 있었다. BJH 기공 크기 분포는 또한 IO CN 1:2가 다른 샘플과 비교하여 2에서 80 nm 범위에서 매우 풍부한 중간 기공을 보유한다는 것을 확인할 수 있었다. The plots of the two catalysts showed a typical type IV isotherm with an H3 hysteresis loop in the range of 0.4-0.95P/P0 based on the International Union of Pure and Applied Chemistry (IUPAC) classification, confirming the presence of a mesoporous structure. The BJH pore size distribution also confirmed that IOCN 1:2 had very abundant mesopores in the range of 2 to 80 nm compared to other samples.
샘플의 기공 부피, 기공 직경 및 BET 비표면적을 표 1에 나타낸다.The pore volume, pore diameter and BET specific surface area of the samples are shown in Table 1.
Pore volume (cm3g-1)Pore volume (cm 3 g -1 ) Pore diameter (nm)Pore diameter (nm) BET surface area (m2g-1)BET surface area (m 2 g -1 )
IO CN3IO CN3 0.250.25 1515 66.7766.77
IO CN2IO CN2 0.120.12 13.5613.56 37.537.5
IO CN1IO CN1 0.120.12 14.814.8 33.3433.34
벌크 CNbulk CN 0.0350.035 21.4321.43 6.56.5
표 2에 나타낸 바와 같이, IO CN3는 66.77 m2g-1의 비표면적 및 0.25 cm3g-1의 기공 부피를 나타내었으며, 이는 다른 샘플보다 높은 수치였다. 이를 통해서 실리카 마이크로스피어를 단단한 템플릿으로 사용하면 표면적이 증가하고 기공 부피가 확대된 계층적 메조포러스 구조를 크게 생성할 수 있음을 확인할 수 있다.As shown in Table 2, IO CN3 exhibited a specific surface area of 66.77 m 2 g -1 and a pore volume of 0.25 cm 3 g -1 , which were higher than other samples. Through this, it can be confirmed that a hierarchical mesoporous structure with an increased surface area and an enlarged pore volume can be generated when silica microspheres are used as a hard template.
[광촉매 성능 평가][Photocatalyst performance evaluation]
합성된 g-C3N4 샘플의 TC와 RhB 분해에 대한 광촉매 성능을 확인하기 위해 하기와 같은 실험을 수행하였다.In order to confirm the photocatalytic performance of the synthesized gC 3 N 4 sample for TC and RhB decomposition, the following experiment was performed.
광촉매 시험 전에 15mg의 촉매를 15mgL-1 농도의 유기 오염 물질(TC 또는 RhB) 수용액 15mL와 혼합하였다. 조사 전에 혼합물을 어두운 상황에서 15분 동안 교반하여, 용액과 촉매가 흡착-탈착 평형을 달성하도록 하였다. 그 후, 광원은 300W 크세논 램프(UV 차단 필터 및 IR 정수 필터(400 < λ < 800 nm)를 사용하여, 가시광선을 혼합물에 조사하였다. 광촉매 반응 동안 15분마다 용액을 회수하고 4000rpm의 속도로 10분간 원심분리한 후 UV-Vis 분광기를 이용하여 오염물질의 잔류 농도를 측정하였다. 다음 방정식 1은 TC와 RhB의 광촉매 분해 효율(PDE)을 나타낸다.Prior to photocatalytic testing, 15 mg of the catalyst was mixed with 15 mL of an aqueous solution of organic pollutants (TC or RhB) at a concentration of 15 mgL -1 . Before irradiation, the mixture was stirred in the dark for 15 minutes to allow the solution and catalyst to achieve adsorption-desorption equilibrium. Then, visible light was irradiated to the mixture using a 300 W xenon lamp (UV cut-off filter and IR water filter (400 < λ < 800 nm) as a light source. During the photocatalytic reaction, the solution was recovered every 15 minutes and rotated at a speed of 4000 rpm). After centrifugation for 10 minutes, residual concentrations of contaminants were measured using UV-Vis spectroscopy, and equation 1 represents the photocatalytic decomposition efficiency (PDE) of TC and RhB.
[방정식 1][Equation 1]
PDE= (C0-Cn)/C0 x 100%PDE= (C 0 -C n )/C 0 x 100%
여기서 CO(mgL-1)는 유기 오염물질의 시작 농도이고 Cn은 조사 시간 t 이후의 오염물질 농도이다.where CO (mgL -1 ) is the starting concentration of the organic pollutant and C n is the pollutant concentration after irradiation time t.
메조포러스 흑연질화탄소 나노클러스터Mesoporous graphitic carbon nitride nanoclusters
g-C3N4 시료의 광촉매 성능을 평가하기 위해 대상 오염물질로 RhB, TC, MB를 선정하였다. 오염물질의 광촉매 분해는 가시광선 조사 하에서 수행되었다. To evaluate the photocatalytic performance of the g-C3N4 sample, RhB, TC, and MB were selected as target contaminants. Photocatalytic decomposition of contaminants was performed under visible light irradiation.
도 6a은 로다민 B (RhB) 분해의 광촉매 분해 곡선이고, 도 6b는 테트라사이클린(TC) 분해의 광촉매 분해 곡선이며, 도 6c는 로다민에 대한 광촉매 분해의 유사 1차 동역학 곡선이고, 도 6d는 테트라사이클린에 대한 광촉매 분해의 유사 1차 동역학 곡선이다.Figure 6a is a photocatalytic degradation curve of rhodamine B (RhB) degradation, Figure 6b is a photocatalytic degradation curve of tetracycline (TC) degradation, Figure 6c is a pseudo first-order kinetic curve of photocatalytic degradation for rhodamine, Figure 6d is a pseudo first-order kinetic curve of photocatalytic degradation for tetracycline.
도 6에 도시한 바와 같이, 가시광선에 의해 유도된 공시험(광분해)은 농도가 변하지 않았기 때문에, 오염물질의 열화를 무시할 수 있는 수준으로 나타났으며, 이는 시험된 촉매의 존재가 TC 및 RhB 제거에 주로 기여함을 확인시켜 주었다. As shown in FIG. 6, the blank test (photolysis) induced by visible light showed a negligible level of deterioration of the contaminant because the concentration did not change, indicating that the presence of the tested catalyst was sufficient to remove TC and RhB. It was confirmed that the main contribution to
흡착 및 광촉매 반응의 기능을 개별적으로 분석하였다. 흡착능력 측면에서 보면 암실 조건에서 30분 반응 후 NC MCN이 동일한 조건의 벌크 CN에 비해 현저한 흡착증가를 보였으며, 현탁액의 흡탈착 평형이 완전히 획득되었다. RhB에 대한 벌크 CN의 분해 효율이 매우 낮고 용액에서 RhB를 완전히 제거하는 데 너무 많은 시간이 소요됨을 관찰할 수 있었다(도 6a 참조). 한편, NC MCN은 이러한 시간을 현저히 단축시켰고 가시광선 조사에서 RhB는 30분 이내에 완전히 분해되었다. The functions of adsorption and photocatalysis were analyzed separately. In terms of adsorption capacity, NC MCN showed a significant increase in adsorption compared to bulk CN under the same conditions after 30 minutes of reaction in the dark, and the adsorption and desorption equilibrium of the suspension was completely obtained. It can be observed that the degradation efficiency of bulk CN to RhB is very low and it takes too much time to completely remove RhB from the solution (see Fig. 6a). On the other hand, NC MCN significantly shortened this time, and RhB was completely decomposed within 30 minutes under visible light irradiation.
TC 분해는 도 6b에 도시한다. 벌크 CN의 TC 분해 능력은 흡착량이 적고 제거 속도가 느리기 때문에 매우 열악하였다. 이에 반하여, NC MCN은 15분 이내에 70% 이상의 분해율과 30분 이내에 완전한 분해로 매우 높은 광촉매 활성을 나타냈으며 이는 LC-MS 분석(섹션 3.10)을 사용하여 입증된다. 또한, 25분 이내에 얻은 두 오염물질의 광촉매 분해 데이터는 유사 1차 동역학 반응에 적합했으며 이는 하기 방정식 2를 이용하여 계산한다.TC decomposition is shown in Figure 6b. The TC decomposition ability of bulk CN was very poor due to the low adsorption amount and slow removal rate. In contrast, NC MCN exhibited very high photocatalytic activity with over 70% degradation within 15 minutes and complete degradation within 30 minutes, which is demonstrated using LC-MS analysis (Section 3.10). In addition, the photocatalytic degradation data of the two contaminants obtained within 25 minutes were suitable for a pseudo first-order kinetic reaction, which is calculated using Equation 2 below.
[방정식 2][Equation 2]
ln(C0/Cn) = ktln(C 0 /C n ) = kt
여기서, k는 1차 동역학 속도상수(min-1)이고, C0와 Cn은 각각 반응시간 0분과 n분에서 오염물질의 농도이다. Here, k is the first-order kinetic rate constant (min -1 ), and C 0 and C n are the concentrations of contaminants at reaction times of 0 and n minutes, respectively.
도 6c에 나타낸 바와 같이, RhB 분해의 kinetic plot에서 NC MCN(0.099 min-1)의 반응속도상수가 벌크 CN(0.025 min-1)보다 약 3.9배 더 높음을 알 수 있다. As shown in Figure 6c, it can be seen that the reaction rate constant of NC MCN (0.099 min -1 ) in the kinetic plot of RhB decomposition is about 3.9 times higher than that of bulk CN (0.025 min -1 ).
NC MCN의 반응속도상수가 벌크 CN에 비해 약 3.4배 증가한 TC 분해에서도 동일한 결과를 얻었다. 결과적으로 NC MCN은 용액에서 RhB와 TC를 제거하는 데 훨씬 더 높은 효율성과 능력을 보였다. NC MCN의 상당히 향상된 광촉매 성능은 더 큰 비표면적, 다공성 구조 및 구조에 질소 결함이 도입되었기 때문이다.The same result was obtained in TC decomposition, in which the reaction rate constant of NC MCN increased by about 3.4 times compared to that of bulk CN. As a result, NC MCN showed much higher efficiency and ability to remove RhB and TC from solution. The significantly improved photocatalytic performance of NC MCN is attributed to the larger specific surface area, porous structure and introduction of nitrogen defects into the structure.
추가로, 오염물질로 MB를 사용하여 NC MCN의 광촉매 성능을 평가하였다. 분해과정은 가시광선 조사하에서 진행하였으며 UV-vis 스펙트럼은 도 7과 같다. 반응시 샘플의 흡착능력은 NC MCN이 MB의 높은 흡착력을 보였다. 광조사 없이 약 30분 반응 후(어두운 조건에서) 흡착-탈착 평형이 달성되었다. 따라서 30분 흡착 실험 후 오염 물질의 추가 제거는 주로 광촉매 분해에 기인한다. NC MCN 촉매는 140분 광촉매 반응에서 MB를 완전히 분해할 수 있는 효율적인 성능을 보였다. 그러나 벌크 CN은 매우 열악한 성능 저하를 보여 50% MB를 저하시키는 데 300분 이상 소요되었다.Additionally, the photocatalytic performance of NC MCN was evaluated using MB as a contaminant. The decomposition process was carried out under visible light irradiation, and the UV-vis spectrum is shown in FIG. 7 . As for the adsorption capacity of the sample during the reaction, NC MCN showed a high adsorption capacity for MB. Adsorption-desorption equilibrium was achieved after about 30 minutes of reaction without light irradiation (under dark conditions). Therefore, further removal of contaminants after the 30-minute adsorption experiment is mainly due to photocatalytic degradation. The NC MCN catalyst showed efficient performance to completely decompose MB in a 140-minute photocatalytic reaction. However, bulk CN showed very poor performance degradation, taking more than 300 minutes to degrade 50% MB.
실제 폐수 분해에 대한 NC MCN의 능력을 분석하는 것이 중요하기 때문에, 실제 폐수를 시뮬레이션하기 위해 용액에 7.5ml MB 15ppm 및 7.5ml RhB 15ppm을 혼합하여 실험을 추가로 수행하였다. Since it is important to analyze the ability of NC MCN for real wastewater degradation, further experiments were conducted by mixing 7.5ml MB 15ppm and 7.5ml RhB 15ppm in the solution to simulate real wastewater.
도 8은 NC MCN의 RhB와 MB 혼합물의 분해 UV-vis 스펙트럼(RhB 및 MB 피크)에 대한 그래프이다. 도 9는 NC MCN의 RhB와 MB 혼합물의 분해 UV-vis 스펙트럼(전체 피크)에 대한 그래프이다.8 is a graph of the decomposition UV-vis spectrum (RhB and MB peaks) of a mixture of RhB and MB of NC MCN. 9 is a graph of the decomposition UV-vis spectrum (all peaks) of a mixture of RhB and MB of NC MCN.
용액에 이전 실험과 동일한 양의 NC MCN 광촉매를 첨가하였다. MB는 600 내지 700 nm 사이에 두 개의 흡수 피크를 갖고, RhB는 550 nm 부근에서 한 개의 흡수 피크를 갖는다. MB와 RhB의 흡수 피크는 순수한 MB가 있는 시간과 비교하여 더 짧은 시간에 사라지고, 두 오염 물질의 완전한 분해는 가시광 조명 내에서 100분에 달성되었다. 이는 RhB와 MB가 단시간 내에 완전히 분해될 수 있음을 나타낸다. 도 9에 200 nm에서 800 nm의 전체 스펙트럼을 나타낸다. 200에서 300 nm 주변의 또 다른 피크가 생성되고 반응이 진행됨에 따라 더 높아지는 것을 관찰할 수 있다. 이는 반응이 진행됨에 따라 원래의 RhB와 MB의 분해 또는 다른 분자의 조합으로 인해 일부 부산물이 생성되기 때문이다.The same amount of NC MCN photocatalyst as in the previous experiment was added to the solution. MB has two absorption peaks between 600 and 700 nm, and RhB has one absorption peak around 550 nm. The absorption peaks of MB and RhB disappeared in a shorter time compared to the time in the presence of pure MB, and complete degradation of both contaminants was achieved within 100 min under visible light illumination. This indicates that RhB and MB can be completely degraded within a short period of time. 9 shows the entire spectrum from 200 nm to 800 nm. Another peak around 200 to 300 nm is generated and it can be observed that it becomes higher as the reaction proceeds. This is because, as the reaction progresses, some by-products are produced due to the decomposition of the original RhB and MB or the combination of other molecules.
역오팔 흑연질화탄소Inverse Opal Graphite Carbon Nitride
역오팔 흑연질화탄소의 광촉매 성능은 대상 오염 물질로서 RhB와 MB를 사용하여 평가되하였다. 분해 과정은 가시광선 조사 및 각 광촉매의 존재하에 개별적으로 수행되었다.The photocatalytic performance of inverse opal graphitic nitride was evaluated using RhB and MB as target contaminants. The decomposition process was individually performed in the presence of visible light irradiation and each photocatalyst.
도 10a는 IO CN 1:2 존재하에서 MB의 UV-Vis 흡수 스펙트럼이고, 도 10b는 준비된 광촉매 존재하에서 MB 분해에 대한 광촉매 분해 곡선이다.10a is a UV-Vis absorption spectrum of MB in the presence of IOCN 1:2, and FIG. 10b is a photocatalytic decomposition curve for MB decomposition in the presence of a prepared photocatalyst.
가시광선 조사 하에서의 광촉매를 사용하지 않은 블랭크 실험은 MB와 RhB에 대한 매우 적은 분해를 보여주었으며, 제조된 광촉매가 있는 상태에서 용액에서 오염물질의 제거는 주로 광촉매 분해 과정에 기인함을 확인하였다. 반응 중 샘플의 흡착능 측면에서 IO CN3는 다른 샘플에 비해 우수한 오염물질의 흡착을 나타내었다.Blank experiments without photocatalyst under visible light showed very little decomposition of MB and RhB, and it was confirmed that the removal of contaminants from the solution in the presence of the prepared photocatalyst was mainly due to the photocatalytic decomposition process. In terms of the adsorption capacity of the sample during the reaction, IO CN3 showed better adsorption of contaminants than other samples.
MB의 경우 광조사 없이 약 60분 반응 후(암 조건에서) 흡탈착 평형이 달성되었다. 따라서 60분 흡착 실험 후 MB의 추가 제거는 주로 광촉매 분해에 기인한 것이다. 도 10b에 도시한 바와 같이, 벌크 CN은 MB 분해 측면에서 가장 낮은 성능을 보였으며, 가시광선 조사 200분 후에 오염물질의 45%만이 제거되었다. IO CN1과 IO CN2는 벌크 CN에 비해 향상된 효능을 보였다. 한편, IO CN3는 110분 광촉매 반응에서 MB를 완전히 분해할 수 있는 성능을 보였으며 이러한 샘플이 다른 샘플에 비하여 효능이 우수함을 확인할 수 있었다.In the case of MB, adsorption/desorption equilibrium was achieved after about 60 minutes of reaction (under dark conditions) without light irradiation. Therefore, the further removal of MB after the 60 min adsorption experiment was mainly due to photocatalytic degradation. As shown in FIG. 10B, bulk CN showed the lowest performance in terms of MB decomposition, and only 45% of the contaminants were removed after 200 minutes of visible light irradiation. IO CN1 and IO CN2 showed improved efficacy compared to bulk CN. On the other hand, IO CN3 showed the ability to completely decompose MB in a 110-minute photocatalytic reaction, and it was confirmed that these samples had better efficacy than other samples.
RhB 분해에 대한 후속 실험을 수행하였다. 도 11a는 IO CN 1:2 존재하에서 RhB의 UV-Vis 흡수 스펙트럼이고, 도 11b는 준비된 광촉매 존재하에서 RhB 분해에 대한 광촉매 분해 곡선이다.Subsequent experiments on RhB degradation were performed. 11a is a UV-Vis absorption spectrum of RhB in the presence of IOCN 1:2, and FIG. 11b is a photocatalytic decomposition curve for RhB decomposition in the presence of a prepared photocatalyst.
벌크 CN의 RhB 분해 능력은 소량의 흡착과 느린 제거 속도와 함께 매우 열악하였다. 이에 반하여 IO CN 1:2는 15분 이내에 80% 이상의 분해율과 25분 이내에 RhB의 완전한 분해를 나타내 매우 높은 광촉매 활성을 나타냈다.The ability of bulk CN to decompose RhB was very poor, with a small amount of adsorption and a slow removal rate. In contrast, IO CN 1:2 exhibited a decomposition rate of over 80% within 15 minutes and complete decomposition of RhB within 25 minutes, showing very high photocatalytic activity.
[광촉매의 안정성 및 재사용성][Stability and Reusability of Photocatalyst]
실제 적용을 위한 광촉매의 능력을 분석하는 과정에서 촉매의 안정성과 재사용성은 상당히 중요하다. 따라서 가시광선 조사에서 NC MCN의 재사용성을 조사하기 위해 동일한 상황에서 8회 연속 재활용 실험을 수행하였다. In the process of analyzing the ability of photocatalysts for practical applications, the stability and reusability of catalysts are very important. Therefore, in order to investigate the reusability of NC MCN under visible light irradiation, 8 consecutive recycling experiments were performed under the same conditions.
도 12는 8 사이클 내의 TC 분해에서 NC MCN의 광촉매 안정성을 나타내는 그래프이다.12 is a graph showing the photocatalytic stability of NC MCN in TC decomposition within 8 cycles.
도 12에 도시한 바와 같이, NC MCN의 비활성화는 감지되지 않았고 TC 제거율은 8주기 분해 후에도 크게 변화하지 않았다. As shown in FIG. 12, inactivation of NC MCN was not detected and the TC removal rate did not change significantly even after 8 cycles of degradation.
또한, 비교를 위해 사용된 촉매의 SEM 이미지를 촬영하여 도 13에 나타내었다. 도 13은 미사용한 NC MCN과 사용한 NC MCN의 SEM 이미지이다.In addition, SEM images of the catalysts used for comparison are taken and shown in FIG. 13 . 13 is a SEM image of an unused NC MCN and a used NC MCN.
NC MCN의 형태는 사용 후에도 변하지 않았음을 알 수 있었다. 이러한 결과는 NC MCN이 높은 재사용성과 안정성을 가지고 있음을 나타낸다. 이를 통해 NC MCN은 가시광선 조사에 의한 오염물질 광분해의 실용화를 위한 안정적이고 효율적인 광촉매로 사용될 수 있다.It was found that the shape of NC MCN did not change even after use. These results indicate that NC MCN has high reusability and stability. Through this, NC MCN can be used as a stable and efficient photocatalyst for practical use of pollutant photolysis by visible light irradiation.
[NC MCN의 향상된 광촉매 메커니즘][Enhanced photocatalytic mechanism of NC MCN]
이러한 실험 결과를 바탕으로 TC와 RhB의 분해에 대한 NC MCN의 향상된 광촉매 활성에 대한 메카니즘을 도 14에 나타낸다.Based on these experimental results, the mechanism for the enhanced photocatalytic activity of NC MCN for the degradation of TC and RhB is shown in FIG. 14 .
도 14에 도시한 바와 같이, 광촉매 반응의 과정은 (i) 광 수확; (ii) 전하 여기 및 전자-정공 쌍 생성; (iii) 전자-정공 쌍의 분리 및 표면 이동; (iv) 표면 흡착 및 산화-환원 반응으로 이루어진다. 따라서, 우수한 광촉매 능력을 가진 NC MCN을 설계함에 있어 이 4가지 단계를 모두 최적화하였다.As shown in FIG. 14, the process of the photocatalytic reaction includes (i) light harvesting; (ii) charge excitation and electron-hole pair generation; (iii) electron-hole pair separation and surface migration; (iv) consists of surface adsorption and oxidation-reduction reactions. Therefore, all these four steps were optimized in designing a NC MCN with excellent photocatalytic ability.
첫째, NC MCN의 다공성 구조와 함께 더 높은 비표면적은 표면 반응에 대한 풍부한 노출 활성 부위와 향상된 물질 전달 과정을 제공하여 RhB와 TC의 효율적인 광분해를 나타낸다. 또한, NC MCN의 메조포러스 구조는 벌크 샘플에 비해 접근 가능한 표면적이 더 높기 때문에 더 효율적인 광 수확 및 활용이 가능하다.First, the higher specific surface area together with the porous structure of NC MCNs provides abundant exposed active sites for surface reaction and enhanced mass transfer process, indicating efficient photolysis of RhB and TC. In addition, the mesoporous structure of NC MCNs has a higher accessible surface area compared to the bulk sample, enabling more efficient light harvesting and utilization.
둘째, NC MCN의 구조에 풍부한 시아노 그룹과 질소 공극이 존재하면, 광 수확 및 전하 분리가 크게 향상된다. 중간 갭 상태가 있는 경우 전도대로 여기되는 것 외에도 전자는 더 긴 파장의 광자를 흡수하여 중간 갭 상태로 여기될 수도 있다. 따라서 결과적으로 가시광선 수확 능력이 크게 향상된다. NC MCN의 전도대 아래 중간 갭 에너지 상태는 전도대로 여기된 전자를 가두어 가전자대에 있는 정공과의 재결합을 방지하여 결과적으로 광 생성 전하의 재결합 속도를 감소시킬 수 있다. 갇힌 전자는 물에 용해된 산소와 반응하여 RhB와 TC 분해에 주도적인 역할을 하는 슈퍼옥사이드 라디칼을 생성한다.Second, the presence of abundant cyano groups and nitrogen vacancies in the structure of NC MCN greatly enhances light harvesting and charge separation. In addition to being excited into the conduction band when there is a mid-gap state, an electron can also be excited into a mid-gap state by absorbing photons of longer wavelengths. As a result, the visible light harvesting ability is greatly improved. The mid-gap energy state below the conduction band of NC MCN can trap electrons excited into the conduction band and prevent recombination with holes in the valence band, consequently reducing the recombination rate of photo-generated charges. The trapped electrons react with dissolved oxygen in water to generate superoxide radicals that play a leading role in the decomposition of RhB and TC.
마지막으로, NC MCN의 VB 가장자리 전위는 벌크 CN에 비해 더 양성이기 때문에, 훨씬 더 나은 산화 능력을 나타내어, 광분해 효능이 우수하다.Finally, since the VB edge potential of NC MCN is more positive compared to bulk CN, it exhibits much better oxidation ability, resulting in superior photolysis efficacy.
따라서 본 출원에서 합성된 NC MCN은 4단계 모두에서 현저한 활성을 나타내어 TC와 RhB의 분해에 현저한 광촉매 활성을 나타냄을 확인할 수 있다.Therefore, it can be confirmed that the NC MCN synthesized in the present application exhibits remarkable activity in all four steps and exhibits remarkable photocatalytic activity for the decomposition of TC and RhB.
[광촉매 분해 및 독성 평가의 가능한 메커니즘][Possible mechanism of photocatalytic degradation and toxicity evaluation]
다양한 조사 시간에서 광촉매 과정 동안 가능한 분해 경로와 생성된 중간체를 확인하기 위해 액체 크로마토 그래피 - 질량 분광법(LC-MS) 기술이 사용한다.A liquid chromatography-mass spectrometry (LC-MS) technique is employed to identify possible degradation pathways and intermediates produced during the photocatalytic process at various irradiation times.
도 15는 TC의 광분해 과정에서 제안된 중간 생산 경로를 나타낸다. m/z 445인 생성물 TC는 3가지 주요 경로에서 분해될 수 있는 테트라사이클린의 분자량에 해당한다. 결과적으로 정수 과정에서 생성된 중간체의 독성을 탐색하는 것은 중요하다. 따라서 TC와 그 생성된 광분해 중간체의 독성을 분석하기 위해 이들 유기물의 급성독성, 생물축적계수, 발달독성 및 변이원성을 추정하였다. 이 추정은 독성 추정 소프트웨어 도구(T.E.S.T.)를 사용하여 정량적 구조-활성 관계(QSAR) 방법을 기반으로 수행되었다. 15 shows the intermediate production pathway proposed in the photolysis process of TC. Product TC, m/z 445, corresponds to the molecular weight of tetracycline that can be cleaved in three major pathways. As a result, it is important to investigate the toxicity of intermediates produced during the purification process. Therefore, in order to analyze the toxicity of TC and its photolysis intermediates, the acute toxicity, bioaccumulation coefficient, developmental toxicity and mutagenicity of these organisms were estimated. This estimation was performed based on the quantitative structure-activity relationship (QSAR) method using the toxicity estimation software tool (T.E.S.T.).
도 16은 NC MCN을 사용하여 광촉매 분해로 생성된 TC 중간체의 독성 평가 결과로서 (a) 급성 독성 LD50; (b) 생물축적계수; (c) 발달 독성 (d) 변이원성에 대한 그래프이다.Figure 16 shows the toxicity evaluation results of TC intermediates produced by photocatalytic degradation using NC MCN (a) acute toxicity LD50; (b) bioaccumulation coefficient; (c) It is a graph for developmental toxicity (d) mutagenicity.
도 16a에 나타낸 바와 같이, 쥐에 대한 TC의 LD50 값은 806.96 mg.kg-1이며, 이는 "매우 독성"으로 평가된다. P12와 P13 외에 다른 모든 중간체는 TC에 비해 LD50 값이 더 높게 나타나 중간체의 급성독성이 감소함을 확인하였다. P12와 P13은 독성이 높지만 TC의 주요 최종 중간체는 P16, P17 및 P18로 LD50 값이 높고 TC보다 독성이 낮다. 또한, 대부분의 중간체의 생물농축계수가 TC보다 높지만 P18의 최종 생성물은 생물축적계수가 낮아 유리하다(도 16b 참조). 도 16c에서 생성된 모든 중간체의 발생독성은 P3를 제외한 모든 중간체의 발생독성이 TC보다 낮음을 알 수 있다. 다만, P4, P9, P10, P14 및 P16의 발달 독성은 발달 무독성 영역에 매우 가까웠다. 또한 TC는 "돌연변이 양성"이며 일부 중간체는 돌연변이 값이 더 높지만 P11에서 P18까지의 최종 중간체는 음성 돌연변이 유발 범위에 있어야 하며 TC보다 훨씬 낮아야 한다(도 16d 참조). 이를 통해, 생성된 대부분의 중간체의 독성이 가시광선 조사 동안 감소하였음을 확인할 수 있었다. 그러나 완전한 무독성 용액을 얻어야 하므로 오염된 물을 정화하기 위해서는 광촉매 반응 시간을 연장하는 것이 바람직하다.As shown in Fig. 16A, the LD50 value of TC for rats is 806.96 mg.kg -1 , which is evaluated as "very toxic". All other intermediates except P12 and P13 showed higher LD50 values than TC, confirming that the acute toxicity of intermediates was reduced. Although P12 and P13 are highly toxic, the major final intermediates of TC are P16, P17 and P18, which have higher LD50 values and are less toxic than TC. In addition, most of the intermediates have higher bioconcentration coefficients than TC, but the final product of P18 has a low bioaccumulation coefficient, which is advantageous (see FIG. 16b). It can be seen from FIG. 16c that the developmental toxicity of all intermediates except P3 is lower than that of TC. However, the developmental toxicity of P4, P9, P10, P14 and P16 was very close to the developmental non-toxicity region. Also, TC is "mutation positive" and some intermediates have higher mutation values, but the final intermediates from P11 to P18 should be in the negative mutagenesis range and should be much lower than TC (see Figure 16d). Through this, it was confirmed that the toxicity of most of the intermediates produced was reduced during visible light irradiation. However, since a completely non-toxic solution must be obtained, it is desirable to extend the photocatalytic reaction time in order to purify contaminated water.
본 출원에 의하면, 다양한 형상의 실리카 입자를 사용하여 흑연질화탄소 광촉매의 다양한 형태와 구조를 합성할 수 있다. 메조포러스 g-C3N4 나노클러스터와 역오팔 g-C3N4 모두 다양한 유기 오염 물질의 분해에 대해 우수한 활성을 보였다. According to the present application, various shapes and structures of graphitic carbon nitride photocatalysts can be synthesized using silica particles of various shapes. Both the mesoporous gC 3 N 4 nanoclusters and the inverse opal gC 3 N 4 showed excellent activity against the degradation of various organic contaminants.
이러한 본 출원의 제조 방법은 간단한 제조 방법으로서, 원료의 용이한 가용성, 광촉매의 형태 및 다공성 엔지니어링, 광촉매의 광촉매 분해 능력 향상, 높은 안정성 및 재사용 가능성을 제공할 수 있다. 이러한 장점으로 인해 실제 응용 분야에 적합하다. 결함이 있는 형상 제어된 g-C3N4의 구성과 TC의 분해, 광물화 및 독성 감소에 대한 본 출원은 폐수 및 환경 오염 개선과 관련된 응용 분야에서 고효율 광촉매를 생산하는 방법을 제공할 수 있다.The manufacturing method of the present application is a simple manufacturing method, and can provide easy availability of raw materials, engineering of shape and porosity of photocatalyst, improvement of photocatalyst decomposition ability of photocatalyst, high stability and reusability. These advantages make it suitable for practical applications. The present application for the composition of defective shape-controlled gC 3 N 4 and the reduction of degradation, mineralization and toxicity of TC may provide a method for producing highly efficient photocatalysts for applications related to wastewater and environmental pollution remediation.
상기에서는 본 출원의 바람직한 실시예를 참조하여 설명하였지만, 해당 기술 분야의 숙련된 당업자는 하기의 특허 청구 범위에 기재된 본 발명의 사상 및 영역으로부터 벗어나지 않는 범위 내에서 본 출원을 다양하게 수정 및 변경시킬 수 있음을 이해할 수 있을 것이다.Although the above has been described with reference to the preferred embodiments of the present application, those skilled in the art can variously modify and change the present application within the scope not departing from the spirit and scope of the present invention described in the claims below. You will understand that you can.

Claims (18)

  1. g-C3N4 및 SiO2 복합체를 형성하는 단계; 및forming a gC 3 N 4 and SiO 2 complex; and
    g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함하는 흑연질화탄소의 제조 방법.A method for producing graphitized carbon, comprising: removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  2. 제 1 항에 있어서,According to claim 1,
    SiO2 템플릿을 제거하는 단계 후, After the step of removing the SiO 2 template,
    SiO2 템플릿이 제거된 잔여물을 원심분리하는 단계;centrifuging the residue from which the SiO 2 template was removed;
    pH가 7이 될 때까지 증류수로 세척하는 단계; 및Washing with distilled water until the pH is 7; and
    오븐에서 60 내지 80 ℃에서 건조하는 단계를 추가로 포함하는제조 방법.A manufacturing method further comprising the step of drying at 60 to 80 ° C. in an oven.
  3. 콜로이드 SiO2 분산액을 건조한 후 분쇄하여 SiO2 클러스터 템플릿을 제조하는 단계;preparing a SiO 2 cluster template by drying and pulverizing the colloidal SiO 2 dispersion;
    SiO2 템플릿과 멜라민을 혼합하여 혼합물을 제조하는 단계;Preparing a mixture by mixing the SiO 2 template and melamine;
    혼합물을 가열하여, g-C3N4 및 SiO2 복합체를 형성하는 단계; 및heating the mixture to form a gC 3 N 4 and SiO 2 composite; and
    g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함하는 흑연질화탄소의 제조 방법.A method for producing graphitized carbon, comprising: removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  4. 제 3 항에 있어서,According to claim 3,
    콜로이드 SiO2 분산액을 80 내지 120 ℃의 오븐에서 건조하는 제조 방법.A manufacturing method in which a colloidal SiO 2 dispersion is dried in an oven at 80 to 120°C.
  5. 제 3 항에 있어서,According to claim 3,
    콜로이드 SiO2 분산액을 10 내지 14 시간 동안 건조하는 제조 방법.A manufacturing method in which the colloidal SiO 2 dispersion is dried for 10 to 14 hours.
  6. 제 3 항에 있어서,According to claim 3,
    SiO2 템플릿과 멜라민을 1 : 1 내지 1.5의 중량비로 혼합하는 제조 방법.A manufacturing method of mixing SiO 2 template and melamine at a weight ratio of 1:1 to 1.5.
  7. 제 3 항에 있어서,According to claim 3,
    혼합물을 550 ℃까지 가열하고 2 내지 4 시간 유지하여, g-C3N4 및 SiO2 복합체를 형성하는 제조 방법.A method for forming a composite of gC 3 N 4 and SiO 2 by heating the mixture to 550° C. and maintaining the mixture for 2 to 4 hours.
  8. 제 3 항에 있어서,According to claim 3,
    불화 수소(HF) 용액을 첨가하여 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 제조 방법.A manufacturing method for removing a SiO 2 template from a gC 3 N 4 and SiO 2 composite by adding a hydrogen fluoride (HF) solution.
  9. SiO2 미소구체를 준비하는 단계; preparing SiO 2 microspheres;
    SiO2 미소구체에 용융 시안아미드(cyanamide)를 혼합하여 혼합물을 제조하는 단계;preparing a mixture by mixing molten cyanamide with SiO 2 microspheres;
    혼합물을 가열하여, g-C3N4 및 SiO2 복합체를 형성하는 단계; 및heating the mixture to form a gC 3 N 4 and SiO 2 composite; and
    g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 단계;를 포함하는 흑연질화탄소의 제조 방법.A method for producing graphitized carbon, comprising: removing the SiO 2 template from the gC 3 N 4 and SiO 2 composite.
  10. 제 9 항에 있어서,According to claim 9,
    시안아미드 및 실리카 미소구체의 중량비는 1 : 0.1 내지 2.5인 제조 방법.The manufacturing method in which the weight ratio of cyanamide and silica microspheres is 1:0.1 to 2.5.
  11. 제 9 항에 있어서,According to claim 9,
    실리카 미소구체의 평균 직경은 200 내지 400 nm인 제조 방법.The method of claim 1, wherein the silica microspheres have an average diameter of 200 to 400 nm.
  12. 제 9 항에 있어서,According to claim 9,
    혼합물을 70 내지 90℃에서 20 내지 40분 동안 혼합하고, 냉각 후 다시 500 내지 600 ℃에서 가열하여 g-C3N4 및 SiO2 복합체를 형성하는 제조 방법.A manufacturing method in which the mixture is mixed at 70 to 90°C for 20 to 40 minutes, cooled, and then heated again at 500 to 600°C to form a gC 3 N 4 and SiO 2 composite.
  13. 제 9 항에 있어서,According to claim 9,
    이불화 수소 암모늄(ammonium hydrogen difluoride) 용액을 첨가하여 g-C3N4 및 SiO2 복합체로부터 SiO2 템플릿을 제거하는 제조 방법.A manufacturing method for removing the SiO 2 template from the gC 3 N 4 and SiO 2 complex by adding an ammonium hydrogen difluoride solution.
  14. 제 1 항 내지 제 13 항 중 어느 한 항의 제조 방법에 의해 제조된 흑연질화탄소.A graphitized carbon produced by the method of any one of claims 1 to 13.
  15. 제 14 항에 있어서,15. The method of claim 14,
    기공의 평균 볼륨은 0.2 내지 0.3 cm3g-1인 흑연질화탄소.Graphitic carbon nitride having an average pore volume of 0.2 to 0.3 cm 3 g -1 .
  16. 제 14 항에 있어서,15. The method of claim 14,
    기공의 평균 직경은 10 내지 20 nm인 흑연질화탄소.Graphitic carbon nitride having an average pore diameter of 10 to 20 nm.
  17. 제 14 항에 있어서,15. The method of claim 14,
    BET 비표면적은 30 내지 70 m2g-1인 흑연질화탄소.Graphitic carbon nitride having a BET specific surface area of 30 to 70 m 2 g -1 .
  18. 제 14 항 내지 제 17 항 중 어느 한 항의 흑연질화탄소를 포함하는 가시광선 광촉매.A visible ray photocatalyst comprising the graphitic carbon nitride of any one of claims 14 to 17.
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