KR101862513B1 - Photocatalyst containing active carbon fiber dispersed with titanium dioxde, and water treatment method using the same - Google Patents

Abstract

The present invention relates to a photocatalyst and a water treatment method using the same. The photocatalyst comprises an activated carbon fiber having a porous structure in which nickel oxide-doped titanium dioxide is physically and chemically bonded and immobilized to the inside and a surface of pores. According to the present invention, immobilization of the photocatalyst becomes easy, and durability is excellent due to outstanding adhesiveness between the activated carbon fiber and titanium dioxide while being reusable. In addition, since the photocatalyst exhibits high photocatalytic activities not only in a UV region but also in a visible light region, the photocatalyst can be useful as a photocatalytic material for water treatment.

Description

TECHNICAL FIELD The present invention relates to a photocatalyst containing activated carbon fiber dispersed with titanium dioxide and a water treatment method using the same,

The present invention relates to a photocatalyst containing activated carbon fiber dispersed with titanium dioxide and a water treatment method using the same.

Titanium dioxide (TiO ₂ ) photocatalysts generate hydroxyl radicals (OH ·) when irradiated with ultraviolet rays on the surface. These radicals completely decompose harmful substances in water into harmless water and carbon dioxide to remove toxic organic compounds. It is known as a substance. Specifically, when the energy of a certain region is applied to the photocatalyst, electron [electron] is formed in the conduction band and holes [h +] are formed in the valence band. Here, the hole (h +) reacts with water to form a hydroxyl radical (OH.), Whereas in the opposite reduction reaction, oxygen in the air is reduced and a superoxide anion (O ^2- ) . In particular, hydroxyl radicals (OH ·) have high oxidation and reduction potential and are excellent for NOx, SOx, volatile organic compounds (VOCs) and various odor purification, and are excellent in BOD of animal wastewater, sewage, factory wastewater, Substances, environmental hormones, etc., as well as 99% or more of pathogenic bacteria and bacteria such as pathogenic Escherichia coli, Staphylococcus aureus, O-157 can be sterilized.

Thus, titanium dioxide photocatalysts have excellent photocatalytic properties and are relatively easy to synthesize. However, since the titanium dioxide photocatalyst is very small, about 0.1 탆 or less in size, it is difficult to fix when it is manufactured by a continuous flow water treatment reactor. In order to recover it after the water treatment, a membrane such as a membrane must be used, And the lifetime of the membrane is shortened. Therefore, there is a limit to lower the removal efficiency of the entire water treatment system.

In order to solve such a problem, techniques for coating titanium dioxide photocatalyst on the surface of polymer fibers have recently been developed. However, the titanium dioxide coated on the surface of the polymer fiber as in the above-mentioned technologies has a low adhesion so that the titanium dioxide coated on the surface of the polymer fiber is easily peeled off during the water treatment process, so that the durability is low and the activity of the reaction site of the photocatalyst is reduced.

Therefore, it is easy to fix the photocatalyst, water treatment can be efficiently performed without loss of the titanium dioxide photocatalyst or separation membrane such as the membrane, high photocatalytic activity in the visible region as well as in the UV region, excellent durability and excellent service life Development of a reusable photocatalytic material is urgently required.

U.S. Patent No. 5,462,674

Textile Science and Engineering, Vol. 42, No. 4, 2005, pp. 235-240

It is an object of the present invention to provide a photocatalyst which can easily fix a photocatalyst, efficiently treat water without loss of a titanium dioxide photocatalyst or a separation membrane such as a membrane, has high photocatalytic activity in a visible region as well as in a UV region, And a water treatment method using the photocatalytic material.

In order to solve the above problems,

The present invention, in one embodiment,

Activated carbon fibers of porous structure; And

The present invention also provides a photocatalyst comprising titanium dioxide doped nickel oxide, physically and chemically bonded to the inside and the surface of the pores of the activated carbon fiber.

In addition, the present invention, in one embodiment,

Immersing the activated carbon fibers in a dispersion containing titanium oxide doped with nickel oxide to obtain activated carbon fibers having titanium oxide doped with nickel oxide formed on its surface and pores; And

And heat treating the activated carbon fiber having titanium oxide doped with nickel oxide inside the surface and pores.

Further, the present invention, in one embodiment,

Contacting an aqueous solution containing an organic compound with a photocatalyst comprising activated carbon fibers of a porous structure in which titanium oxide doped with nickel oxide is dispersed in pores and on the surface to adsorb an organic compound on the photocatalyst; And

Irradiating a photocatalyst on which an organic compound is adsorbed to photodegrade the organic compound,

Wherein the light has a wavelength of 200 to 800 nm.

In addition, the present invention, in one embodiment,

An injection port into which an aqueous solution containing an organic compound is injected;

A filtration unit adsorbing an organic compound of an aqueous solution injected from the injection port and containing the photocatalyst;

An outlet through which the aqueous solution from which the organic compound has been removed is discharged; And

And a lamp for irradiating light to the filtration unit.

The photocatalyst according to the present invention is characterized in that the titanium dioxide doped with nickel oxide is physically and chemically bonded to the inside and the surface of the pore to fix the activated carbon fiber having the porous structure and is easy to fix the photocatalyst and the adhesion between the activated carbon fiber and titanium dioxide Is excellent in durability and can be reused, and exhibits a high photocatalytic activity not only in the UV region but also in the visible region, so that it can be usefully used as a photocatalytic material for water treatment.

1 is an image showing a result of a scanning electron microscope (SEM) analysis of a photocatalyst.
2 is a graph showing the energy dispersive X-ray spectroscopy (EXD) of activated carbon fiber (ACF) and photocatalyst.
3 is a graph showing activated carbon fibers (ACF) and X-ray diffraction (XRD) by photocatalyst type.
4 is a graph showing X-ray photoelectron spectroscopy (XPS) results of a photocatalyst.
5 is a graph showing the formaldehyde removal rate of the photocatalyst according to the pH of the treated water.
6 is a graph showing the formaldehyde removal rate of the photocatalyst according to the kind of the photocatalyst and the wavelength of the irradiation light.
7 is a graph showing the formaldehyde removal rate of the photocatalyst with respect to time according to the addition amount of hydrogen peroxide.
FIG. 8 is a graph showing equilibrium isotherm data at the time of photocatalytic decomposition of the photocatalyst. FIG. 8 (a) is a result obtained by the Langmuir method, and FIG. 8 (b) ) Method.
9 is a graph showing the formaldehyde removal rate according to the number of times of repeated use of the photocatalyst.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the present invention, the terms " comprising " or " having ", and the like, specify that the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

In the present invention, an activated carbon fiber (ACF) is a carbon material having a fiber form and is composed of a carbon atom (C) and an oxygen atom (O) because it contains a carboxyl group (-COOH) And may be structurally characterized as having a shallow depth and a large specific surface area including pores having an average diameter of about 1 to 2 nm. The activated carbon fiber can be used in the form of a molded product obtained by using the fiber itself or by molding such as compression or knitting.

The present invention relates to a photocatalyst and a water treatment method using the same.

Titanium dioxide (TiO ₂ ) photocatalyst generates OH radicals (OH ·) when ultraviolet rays are irradiated on the surface. This radical completely decomposes harmful substances in water into harmless water and carbon dioxide to remove toxic organic compounds. And it has been actively studied. However, such a titanium dioxide photocatalyst is very small, about 0.1 탆 or less in size, so that it is difficult to fix it when it is manufactured by a continuous flow water treatment reactor. In order to recover it after water treatment, a membrane such as a membrane must be used, So that the lifetime of the membrane is shortened. Therefore, there is a limit to lower the removal efficiency of the entire water treatment system. In order to solve such a problem, techniques for coating titanium dioxide photocatalyst on the surface of polymer fibers have recently been developed. However, the titanium dioxide coated on the surface of the polymer fiber as in the above-mentioned techniques has a low adhesion strength and easily peeled off during the water treatment process, so that the durability is low.

Accordingly, the present invention provides a photocatalyst comprising activated carbon fibers dispersed in the surface and pores of titanium dioxide, and a water treatment method using the same.

The photocatalyst according to the present invention is characterized in that the titanium dioxide doped with nickel oxide is physically and chemically bonded to the inside and the surface of the pore to fix the activated carbon fiber having the porous structure and is easy to fix the photocatalyst and the adhesion between the activated carbon fiber and titanium dioxide Is excellent in durability and can be reused, and exhibits a high photocatalytic activity not only in the UV region but also in the visible region, so that it can be usefully used as a photocatalytic material for water treatment.

Hereinafter, the present invention will be described in more detail.

Photocatalyst

The present invention, in one embodiment,

Activated carbon fibers of porous structure; And

The present invention also provides a photocatalyst comprising titanium dioxide doped nickel oxide, physically and chemically bonded to the inside and the surface of the pores of the activated carbon fiber.

The photocatalyst according to the present invention includes an activated carbon fiber (ACF) having a porous structure as a support, and titanium dioxide doped with nickel oxide in the surface and pores of the activated carbon fiber (ACF) Gt; structure. ≪ / RTI > Specifically, the surface of the activated carbon fiber and pores having an average diameter of about 50 to 300 nm have an average diameter of 10 to 300 nm, specifically 50 to 250 nm, 75 to 250 nm, 100 to 200 nm, 10 to 100 nm, 10 to 50 nm, 50 to 150 nm, 150 to 200 nm, 90 to 130 nm, 100 to 150 nm, or 100 to 120 nm. Here, the titanium dioxide is physically and chemically bonded to the doped nickel oxide to form a chemical bond (Ti-O) that shares an oxygen atom (O) between the nickel atom (Ni) of titanium oxide and the titanium atom (Ti) -Ni), and the chemical coupling with the nickel atom (Ni) can increase the efficiency of photo-generated electrons to increase the activity of the photocatalyst. Titanium dioxide is a chemical bond (Ni-O-Si) that has a shape dispersed in the surface and pores of activated carbon fibers (ACF), but shares carbon atoms (C) and oxygen atoms (O) Ti-OC, and / or Ni-O (-C) -Ti). Titanium dioxide has such a chemical bond that it shares carbon atoms (C) and oxygen atoms (O), thereby improving adhesion between titanium dioxide (TiO ₂ ) and activated carbon fibers (ACF) And holes can be formed, so that the photocatalytic activity can be increased.

At this time, the photocatalyst includes nickel oxide, titanium dioxide, and activated carbon fiber as a main component, and may include activated carbon fiber as a main component. As one example, the photocatalyst may include 30 to 45 parts by weight of carbon, 40 to 64 parts by weight of oxygen, 5 to 15 parts by weight of titanium, and 1 to 10 parts by weight of nickel, specifically, 35 to 40 parts by weight of carbon 44 to 53 parts by weight of oxygen, 8 to 10 parts by weight of titanium and 4 to 6 parts by weight of nickel. The present invention has the above-described composition including the activated carbon fiber as a main component, thereby achieving high photocatalytic activity with a small amount of photocatalyst and minimizing loss of titanium dioxide having photocatalytic activity.

In addition, since the photocatalyst includes a porous structure of activated carbon fiber as a support, it can have a high surface area. Therefore, when the photocatalyst is used as a photocatalyst for water treatment, contaminants remaining in water can be adsorbed on the surface thereof . The photocatalyst may have an average BET specific surface area of 50 to 200 m 2 / g, more specifically 80 to 200 m 2 / g, 50 to 150 m 2 / g, 80 to 150 m 2 / g, and 90 to 180 m 2 / g G, 90 to 120 m2 / g, 90 to 110 m2 / g, 100 to 120 m2 / g, 105 to 115 m2 / g, 90 to 140 m2 / g, G, from 150 to 190 m 2 / g, from 150 to 190 m 2 / g, from 100 to 200 m 2 / g, from 120 to 200 m 2 / g, from 140 to 200 m 2 / g, G, 100 to 180 m 2 / g, 100 to 160 m 2 / g, 120 to 150 m 2 / g, 90 to 110 m 2 / g, or 150 to 170 m 2 / g.

In addition, since the photocatalyst includes titanium dioxide exhibiting catalytic activity with respect to the conventional UV region light, the titanium dioxide is doped with nickel oxide so that the HOMO-LUNO energy level is regulated. Therefore, not only light in the UV region but also light in the visible region Activity.

Here, the nickel oxide may suitably include compounds such as NiO, NiO ₂ , and Ni ₂ O ₃ including nickel atoms (Ni) and oxygen atoms (O). In the present invention, one oxygen atom (O) May include a directly bonded NiO to which one nickel atom (Ni) is bonded. Unlike NiO ₂ and Ni ₂ O ₃ , NiO can be easily substituted with titanium dioxide crystals, so that the band gap can be easily lowered without changing the crystal phase of titanium dioxide.

The titanium dioxide may have a crystal form such as anatase, rutile, brookite and the like, and specifically may have a crystal form of anatase and rutile.

As one example, the photocatalyst according to the present invention exhibits anatase and rutile of titanium dioxide (TiO ₂ ) together with peaks at 2θ = 22.6 ± 1 ° and 44.0 ± 1 °, which indicate amorphous activated carbon fibers during X- 25.5 ± 1, 37.9 ± 1 °, 48.2 ± 1 °, 54.1 ± 1 °, 55.1 ± 1 ° and 75.4 ± 0.5 ° representing the rutile crystal phase. In addition, the photocatalyst may further include peaks of 2θ = 43.6 ± 1 °, 44.7 ± 1 ° and 63.2 ± 1 ° by doping titanium dioxide with nickel oxide. The peaks of 2θ = 43.6 ± 1 °, 44.7 ± 1 °, and 63.2 ± 1 ° were obtained from the tetravalent titanium ions (Ti ^{4 +} ) contained in the titanium dioxide crystals as divalent nickel ions (Ni ^{2 +} ), The peaks of 2? = 43.6 占 and 44.7 占? Are not overlapped with each other and the peaks of 2? = 43.6 占 1 占 are more intense than the peaks of 2? = 44.7 占 占Can be seen.

Further, the photocatalyst may have a band gap of 2.4 to 2.6 eV in the wavelength range of 400 nm to 800 nm, specifically 2.4 to 2.55 eV; 2.45 to 2.6 eV; 2.45 to 2.55 eV; 2.43 to 2.51 eV; 2.4 to 2.5 eV; 2.42 to 2.47 eV; Or 2.44 to 2.46 eV. Photocatalytic photoreaction excites electrons from the valence band to the conduction band to form electrons in the conduction band and to form holes in the valence band. Here, the formed electrons and holes diffuse to the surface of the photocatalyst and participate in the oxidation-reduction reaction to decompose contaminants remaining in the water. The photocatalyst of the present invention has a gap between the valence band and the conduction band, that is, It is advantageous to perform a photoreaction with high efficiency even in visible light.

Photocatalyst  Manufacturing method

In addition, the present invention, in one embodiment,

Immersing the activated carbon fibers in a dispersion containing titanium oxide doped with nickel oxide to obtain activated carbon fibers having titanium oxide doped with nickel oxide formed on its surface and pores; And

And heat treating the activated carbon fiber having titanium oxide doped with nickel oxide inside the surface and pores.

The method of manufacturing a photocatalyst according to the present invention is characterized in that the activated carbon fiber is immersed in a titanium dioxide dispersion doped with nickel oxide obtained through a sol-gel method to penetrate titanium dioxide doped with nickel oxide on the surface and pores of the activated carbon fiber, The surface of the activated carbon fiber and the titanium dioxide doped with nickel oxide in the pores can be uniformly fixed through physical and chemical bonding.

The heat treatment may be performed in a nitrogen atmosphere such as nitrogen (N ₂ ), argon (Ar) or argon (Ar) so that the carbon atoms (C) of the activated carbon fibers (ACF) and the titanium atoms ), And an inert gas atmosphere at a temperature of 300 to 600 DEG C for 10 minutes to 200 minutes. Specifically, the heat treatment is a nitrogen gas (N ₂₎ at 400 to 600 ℃, 300 to 500 ℃, 350 to 450 ℃, 450 to 550 ℃, 390 to 510 ℃, 380 to 420 ℃ or 480 to a temperature of 520 ℃ atmosphere From 10 minutes to 150 minutes, from 30 minutes to 150 minutes, from 60 minutes to 150 minutes, from 80 minutes to 150 minutes, from 100 minutes to 150 minutes, from 10 minutes to 60 minutes, from 30 minutes to 90 minutes, To 130 minutes.

Water treatment  Way

Further, the present invention, in one embodiment,

Contacting an aqueous solution containing an organic compound with a photocatalyst comprising activated carbon fibers of a porous structure in which titanium oxide doped with nickel oxide is dispersed in pores and on the surface to adsorb an organic compound on the photocatalyst; And

Irradiating a photocatalyst on which an organic compound is adsorbed to photodegrade the organic compound,

Wherein the light has a wavelength of 200 to 800 nm.

In the water treatment method according to the present invention, the organic compound is adsorbed by bringing the photocatalyst of the present invention into contact with an aqueous solution containing an organic compound as described above, and photolyzed by irradiating ultraviolet rays and / or visible rays having a wavelength of 200 to 800 nm, The residual organic compound can be removed with high efficiency.

At this time, in order to maximize the adsorption rate of the organic compound and the photocatalyst present in the aqueous solution, the pH of the aqueous solution containing the organic compound may be 3 to 7, and the concentration of the organic compound contained in the aqueous solution may be 500 mg or less. Specifically, the pH of the aqueous solution is 3.5 to 6.5; 3.8 to 6.1; 3 to 5; 4 to 5; 5 to 6; 5 to 7; 5 to 6.5; 6 to 7; 3.5 to 4.5; 3.7 to 4.3; 3.9 to 4.1; 5.5 to 6.5; 5.7 to 6.3 or 5.9 to 6.1, and the concentration of the organic compound is 400 mg or less per liter of the aqueous solution containing the organic compound; 300 mg or less; 0.1 to 250 mg; 0.1 to 200 mg; Or 0.1 to 150 mg.

In addition, the aqueous solution containing the organic compound may further include hydrogen peroxide (H ₂ O ₂ ) to improve the catalytic activity of the photocatalyst. The hydrogen peroxide reacts with the photocatalyst to provide a hydroxyl radical (OH.) Which decomposes organic compounds in water, thereby improving the efficiency of photolysis of organic compounds in water. Here, the concentration of the hydrogen peroxide may be 0.0001 to 0.5% by weight based on the aqueous solution, and may be specifically 0.0001 to 0.2, 0.0001 to 0.1, 0.0001 to 0.09, or 0.0005 to 0.05. Hydrogen peroxide reacts with hydroxyl radicals formed by the photocatalyst and acts as an inhibitor which inhibits the decomposition of the organic compound when the hydrogen peroxide is present in the aqueous solution to be water-treated at a concentration exceeding the above range.

Meanwhile, the water treatment method according to the present invention may further include a heat treatment step of regenerating the photocatalyst by applying heat to the photocatalyst after the step of photodecomposing the organic compound in the water using the photocatalyst. Conventionally, in order to increase the specific surface area, a photocatalyst containing carbon particles such as activated carbon or a titanium dioxide photocatalyst in the form of a powder doped with a transition metal atom has difficulty in recovering after water treatment and has low structural stability, There is a problem that the photocatalytic activity of the photocatalyst is remarkably lowered due to loss of components or deformation of the catalytic reaction site. However, since the photocatalyst according to the present invention has a structure in which titanium dioxide is physically and chemically bonded to the activated carbon fiber as the support, the photocatalyst has an excellent photocatalytic activity even after regeneration through heat treatment because of its excellent structural stability.

At this time, the heat treatment temperature may be 100 ° C. to 250 ° C., 100 ° C. to 200 ° C., 100 ° C., and more preferably 100 ° C. to 100 ° C., at which the organic compounds remaining in the photocatalyst can be completely removed, To 150 캜, 150 캜 to 300 캜, 200 캜 to 300 캜, 150 캜 to 250 캜, 180 캜 to 220 캜, 120 캜 to 170 캜, 250 캜 to 300 캜, or 240 캜 to 260 캜 .

Water treatment  Device

In addition, the present invention, in one embodiment,

An injection port into which an aqueous solution containing an organic compound is injected;

A filtration unit including the photocatalyst according to the present invention for adsorbing an organic compound of an aqueous solution injected from the injection port;

An outlet through which the aqueous solution from which the organic compound has been removed is discharged; And

And a lamp for irradiating light to the filtration unit.

The water treatment apparatus according to the present invention includes a filtration unit including a photocatalyst including titanium dioxide doped with nickel oxide and a photocatalyst containing activated carbon fibers uniformly dispersed in the pores to decompose the organic compound contained in the aqueous solution at a high rate It is excellent in the effect of removing the organic compounds remaining in the aqueous solution such as industrial wastewater and agricultural wastewater.

At this time, although the shape of the water treatment apparatus is not particularly limited, an injection port through which an aqueous solution containing an organic compound is injected is disposed in an upper part of a filtration part provided with a adsorption bed including a photocatalyst of the present invention, And a discharge port through which the aqueous solution from which the organic compound is removed through the adsorption bed of the filtration part is located. Here, the adsorption bed includes the photocatalyst according to the present invention, and the photocatalyst having a fiber form may be directly used, or may be used in the form of a felt or a film which has been formed by compression, knitting or the like.

The water treatment apparatus may include a lamp for irradiating light to the inside of the filtration unit to decompose organic compounds adsorbed on the photocatalyst. The lamp is particularly limited as long as it can emit light having a wavelength of 200 to 800 nm. . For example, the lamp may be a UV lamp that emits ultraviolet light, a light emitting device that can emit visible light, and the like.

Further, the water treatment apparatus may further comprise: pH and temperature of the aqueous solution to be injected; But the present invention is not limited thereto. The measurement unit may measure the contact time between the aqueous solution and the photocatalyst.

The water treatment apparatus according to the present invention is provided with a filtration unit including the photocatalyst of the present invention, so that no additional separation membrane is required for recovering the loss of the photocatalyst or recovering the photocatalyst during the water treatment. Therefore, the titanium dioxide, There is an advantage that a separate configuration is not necessary.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the present invention is not limited to the following Examples and Experimental Examples.

Example  One.

Titanium isopropoxide (TIP 7.44 mL) and ethanol (80 mL) were added to the injected acetic acid, and the mixture was stirred at 30 ° C for 25 minutes, Decomposition. Then, the reactant was mixed with distilled water (80 mL) dissolving 0.3 wt% of nickel nitrate, and a felt (3 cm x 3 cm long, 1 g) made of activated carbon fiber (ACF) was immersed in the solution Followed by sonication for 30 minutes. The felt made of activated carbon fiber was taken out from the ultrasonic irradiated solution, washed with ethanol, dried at 85 ° C for 8 hours, and then heat-treated at 550 ° C for 2 hours in a nitrogen (N ₂ ) atmosphere to form pores of activated carbon fibers (NiO-TiO ₂ / ACF, average BET specific surface area: 109 ± 10 ㎡ / g) was prepared by physical and chemical bonding of titanium dioxide doped with nickel oxide on the inside and the surface thereof.

Comparative Example  One.

Titanium isopropoxide (TIP 6.50 mL) and ethanol (75 mL) were added to the injected acetic acid, and the mixture was stirred at 30 ° C. for 25 minutes. Decomposition. Then, a felt (3 cm x 3 cm, 1 g) made of activated carbon fibers was immersed in the solution and ultrasonically irradiated for 45 minutes. The felt made of activated carbon fibers was taken out from the ultrasonic irradiated solution, washed with ethanol, dried at 90 ° C. for 6 hours, and heat-treated at 400 ° C. for 2 hours in a nitrogen (N ₂ ) atmosphere to form pores of activated carbon fibers (TiO ₂ / ACF) in which titanium dioxide is fixed on the inside and the surface of the photocatalyst.

Experimental Example  One.

Scanning Electron Microscope (SEM) photographs of the activated carbon fibers (ACF) and the photocatalyst prepared in Example 1 and Comparative Example 1 were carried out in order to confirm the shape and content of the photocatalyst according to the present invention , And energy dispersive X-ray spectroscopy (EDX) was continuously measured while scanning electron microscope (SEM) photographing. X-ray diffraction (XRD) of the above materials was measured. X-ray photoelectron spectroscopy (XPS) was measured on the photocatalyst of Example 1, and the measured results Are shown in Figs.

1, the photocatalyst (NiO-TiO ₂ / ACF) of Example 1 according to the present invention includes activated carbon fibers (ACF) having a porous structure, and the activated carbon fibers are doped with nickel oxide on the surfaces and pores Titanium oxide (TiO ₂ ) particles (average particle size: 75 to 250 nm) are uniformly formed. On the other hand, the photocatalyst (TiO ₂ / ACF) of Comparative Example 1 which does not contain nickel oxide has a structure in which titanium dioxide (TiO ₂ ) particles are uniformly adsorbed on the surface of activated carbon fibers (ACF) Respectively.

2, the active carbon fibers (ACF) were 95.3 ± 0.05% and 4.7 ± 0.05%, respectively, when analyzed by energy dispersive X-ray spectroscopy (EDX) NiO-TiO ₂ / ACF) showed 38.5 ± 0.05%, 46.2 ± 0.05%, 9.1 ± 0.05% and 5.2 ± 0.05% of carbon atoms, oxygen atoms, titanium atoms and nickel atoms, respectively.

3, the active carbon fiber (ACF) had an amorphous crystal form and peaks at 2? = 22.6 ± 0.5 ° and 44.0 ± 0.5 ° were observed, while the catalyst of Example 1 according to the present invention had activated carbon fibers (ACF ) it was found to represent the surface of the titanium dioxide within the pores (TiO ₂₎ when the particles are located by X-ray diffraction measurement of anatase (anatase) and rutile (rutile) titanium dioxide crystal on the (TiO _2). Specifically, in Example 1 of the photocatalyst it is 2θ = 25.5 ± 0.5 ° [1,0,1 ], 37.9 ± 0.5 ° [0,0,4], 48.2 ± 0.5 ° indicating a titanium dioxide (TiO _{2) [2,} Peaks of [0,0], 54.1 ± 0.5 ° [1,0,5], 55.1 ± 0.5 ° [2,1,1] and 75.4 ± 0.5 ° [2,1, 5] Unlike the photocatalyst of Comparative Example 1, peaks at 2? = 43.6 ± 0.5 °, 44.7 ± 0.5 ° and 63.2 ± 0.5 ° were further confirmed. These peaks mean that tetravalent titanium ions (Ti ⁴⁺ ) contained in the titanium dioxide crystals are partially substituted with ^divalent nickel ions (Ni ^{2 +} ) having similar ionic radii.

4, the photocatalyst of Example 1 showed binding energy peaks of Ni2p1 / 2 and Ni2p3 / 2 indicating binding characteristics of nickel atoms at 855.5 ± 0.5 eV and 861.2 ± 0.5 eV. The peak indicates the presence of nickel ion (Ni ^{2 +} ). It can be seen that titanium dioxide is doped with nickel oxide, so that oxygen atoms and titanium atoms of titanium dioxide are chemically bonded.

From these results, it can be seen that the photocatalyst according to the present invention has a structure in which the surface of the activated carbon fiber (ACF) having a porous structure and titanium dioxide (TiO ₂ ) doped with nickel oxide (NiO) are uniformly dispersed in the pores, Titanium (TiO ₂ ) is a structure in which nickel atoms of nickel oxide (NiO) and carbon atoms of activated carbon fibers (ACF) are chemically bonded and immobilized on activated carbon fibers, respectively.

Experimental Example  2.

The following experiment was conducted to evaluate the optical properties of the photocatalyst according to the present invention.

The absorbance of the photocatalyst and the activated carbon fiber (ACF) prepared in Example 1 and Comparative Example 1 was measured in a wavelength range of 280 to 800 nm and the absorbance measured using a Tauc plot was used to calculate the photocatalyst band Gaps. The measured results are shown in Table 1 below.

Band gap Example _{1 (NiO-TiO 2 / ACF} ) 2.45 ± 0.05 eV Comparative Example 1 (TiO ₂ / ACF) 2.89 ± 0.05 eV

As shown in Table 1, the photocatalyst (NiO-TiO ₂ / ACF) of Example 1 according to the present invention has a low band gap of less than 3 eV including nickel dioxide (NiO) -doped titanium dioxide, The photocatalyst (TiO ₂ / ACF) of Comparative Example 1 containing titanium dioxide which has not been found has a high band gap exceeding 3 eV.

From these results, it can be seen that the photocatalyst according to the present invention can absorb light in the visible region at a high rate including titanium dioxide doped with nickel oxide, and has a low band gap of less than 3 eV.

Experimental Example  3.

In order to evaluate the water treatment efficiency of the photocatalyst according to the present invention, the following experiment was conducted.

(1) Depending on the pH of the treated water Water treatment  Efficiency evaluation

A 500 ml flask was installed in a photoreactor capable of irradiating ultraviolet rays (250 ± 50 nm) and visible light (300 nm to 800 nm, wavelength of irradiated light: 550 ± 20 nm), and a flask was charged with 100 mg / , 0.1 g of the photocatalyst prepared in Example 1 and Comparative Example 1 were added, and the concentration of formaldehyde was measured over time for 2 hours. At this time, the pH of the distilled water in which formaldehyde was dissolved was adjusted to 1 to 11, and the temperature was maintained at 30 ± 1 ° C. The removal efficiency of formaldehyde was deduced from the measured results, and the results are shown in Table 2 and FIG.

Formaldehyde removal rate [pH = 6] UV light irradiation Visible light irradiation Example _{1 (NiO-TiO 2 / ACF} ) 58.6 ± 1% 92.1 ± 1% Comparative Example 1 (TiO ₂ / ACF) 36.8 ± 1% -

Table 2 and FIG. 5 show that the photocatalyst of Example 1 according to the present invention exhibited a very low photocatalytic activity in the range of pH less than 2 and exceeding 8, and a photocatalytic activity of 20% or more at pH 2 to 8 Respectively. Specifically, the photocatalyst of Comparative Example 1 in which nickel oxide was not doped did not photo-decompose formaldehyde present in water when light of a wavelength of 300 to 800 nm, which is a visible light region, was irradiated, Formaldehyde was photolyzed with a low removal rate of less than 40%. However, in the photocatalyst of Example 1, formaldehyde was photodecomposed at a removal rate of 20 to 60% under the condition that light having a wavelength of 300 nm or less was irradiated, 40 to 94% of the photocatalyst was irradiated with light having a wavelength of 300 to 800 nm, The photolysis was carried out at a removal rate of. In particular, it has been found that the pH exhibits a high removal rate irrespective of the wavelength of the light to be irradiated at a neutral pH of from 5 to 7, more specifically from pH 5.8 to 6.2. This is due to the protonation of the carboxyl group (-COOH) present on the surface of activated carbon fibers (ACF) and the electrostatic attraction with formaldehyde present in the water is increased.

(2) Light irradiation  Conditional Water treatment  Efficiency evaluation

A 500 ml flask was installed in a photoreactor capable of irradiating ultraviolet rays (250 ± 50 nm) and visible light (300 nm to 800 nm, wavelength of irradiated light: 550 ± 20 nm), and a flask was charged with 100 mg / 100 ml of distilled water in which formaldehyde was dissolved was added, and 0.1 g of each of the photocatalysts prepared in Example 1 and Comparative Example 1 was added, and the concentration of formaldehyde was measured over time for 3 hours. At this time, the pH of the distilled water in which formaldehyde was dissolved was adjusted to 6 ± 0.5, and the temperature was maintained at 30 ± 1 ° C. The removal efficiency of formaldehyde was deduced from the measured results, and the results are shown in FIG.

Referring to FIG. 6, the photocatalyst (NiO-TiO ₂ / ACF) of Example 1 according to the present invention exhibits a formaldehyde removal rate of about 50% or more after 1 hour of water treatment in UV region light irradiation of less than 300 nm, In the case of the photocatalyst (TiO ₂ / ACF) of Comparative Example 1 containing nickel-undoped titanium dioxide, it was confirmed that the removal rate was about 30% after one hour of water treatment. In addition, the photocatalyst of Comparative Example 1 did not exhibit photocatalytic activity in the visible light region irradiation of 300 nm to 800 nm, but the photocatalyst of Example 1 was excellent in photocatalytic activity and showed a high removal rate of 75% to 95% after 1 hour of water treatment . From these results, it can be seen that the photocatalyst of the present invention has excellent optical activity for light in the visible region as well as light in the UV region.

(3) Depending on the amount of hydrogen peroxide added Water treatment  Efficiency evaluation

A 500 ml flask was installed in a photoreactor capable of irradiating ultraviolet rays (250 ± 50 nm) and visible light (300 nm to 800 nm, wavelength of irradiated light: 550 ± 20 nm), and a flask was charged with 100 mg / 100 ml of distilled water in which formaldehyde and hydrogen peroxide (H ₂ O ₂ ) were dissolved was added. Then, 0.1 g of the photocatalyst of Example 1 was added and the concentration of formaldehyde was measured over time for 3 hours. At this time, the pH of distilled water in which formaldehyde was dissolved was adjusted to 6 ± 0.5, the temperature was maintained at 30 ± 1 ° C., and the concentration of hydrogen peroxide was adjusted to 0.001 to 0.5% by weight with respect to distilled water. From the measured results, the initial concentration (C ₀ ) of phenol and the concentration (C _t ) of formaldehyde for each reference time were derived, and the results are shown in FIG.

As shown in FIG. 7, the photocatalytic efficiency of the photocatalyst of Example 1 according to the present invention was improved when a certain amount of hydrogen peroxide was used as an additive during water treatment, but the efficiency of photocatalytic degradation was remarkably decreased together with a certain amount of hydrogen peroxide as an additive.

Specifically, in the photocatalyst of Example 1, when hydrogen peroxide was not used during water treatment, formaldehyde present in water was removed at a removal rate of 92.1 ± 1%, and hydrogen peroxide (H ₂ O ₂ ) %, The removal rate of formaldehyde could be increased up to 98.4 ± 1%. However, when the concentration of hydrogen peroxide was 0.1% by weight or more based on the treated water, the formaldehyde removal rate was reduced to 76.2 ± 1%. This means that an excessive amount of hydrogen peroxide is formed by the titanium dioxide and acts as an inhibitor which inhibits photodegradation by reacting with a hydroxyl radical (OH.) Which decomposes formaldehyde.

(4) Photocatalyst  Depending on the type Water treatment  Efficiency evaluation

A 500 ml flask was installed in a photoreactor capable of irradiating ultraviolet rays (250 ± 50 nm) and visible light (300 nm to 800 nm, wavelength of irradiated light: 550 ± 20 nm), and a flask was charged with 100 mg / 100 ml of distilled water in which formaldehyde was dissolved was added, and 0.1 g of each of the photocatalysts prepared in Example 1 and Comparative Example 1 was added and water treatment was performed for 5 hours. At this time, the pH of the distilled water in which formaldehyde was dissolved was adjusted to 6 ± 0.5, the temperature was maintained at 30 ± 1 ° C, and the decomposition efficiency of formaldehyde was determined by Langmuir adsorption isotherm and proindrihydration isotherm (Freundlich adsorption isotherm) and is shown in Table 3 and FIG.

Cancer Conditions UV irradiation condition Conditions for visible light irradiation Activated carbon fiber Example 1 Comparative Example 1 Example 1 The average removal capacity of the photocatalyst, q _max
[Mg / g] 63.1 ± 0.1 109.2 ± 0.1 86.2 ± 0.1 126.3 ± 0.5 Binding constant at adsorption, b
[Ml / g] 16.05 ± 0.1 30.93 + - 0.1 17.39 ± 0.1 59.36 ± 0.1 Formaldehyde adsorption amount, Kf
[Mg / g] 17.36 ± 0.1 27.06 + - 0.1 20.49 + 0.1 53.5 ± 0.5

First, referring to Table 3 and FIG. 8, it can be seen that the photocatalyst according to the present invention efficiently adsorbs organic compounds present in water as well as adsorbed organic compounds.

Specifically, in the photocatalyst of Example 1, 100 mg to 120 mg of formaldehyde present in water under the UV irradiation condition can be removed on an average basis, and 120 mg to 130 mg per g of g . On the other hand, the photocatalyst of Comparative Example 1 was not capable of photodecomposing formaldehyde present in water under the visible light irradiation condition, and it was found that 80 mg to 90 mg of the photocatalyst could be removed per unit g under the UV irradiation condition.

Further, the activated carbon fiber (ACF) and the photocatalyst of Comparative Example 1 had a low adsorption amount of about 19 to 21 mg per gram at a binding constant of about 15 to 20 ml / g for formaldehyde under dark or UV irradiation conditions Respectively. However, the photocatalyst of Example 1 according to the present invention has a binding constant for formaldehyde of about 25 to 35 ml / g and has an adsorption amount of 24 to 29 mg per unit g under UV irradiation condition, It has been found that the binding constant for formaldehyde in the conditions is from about 55 to 65 ml / g and has a high adsorption amount of from 50 to 55 mg per unit g.

From these results, it can be seen that the titanium dioxide doped with nickel oxide contains activated carbon fibers uniformly physically and chemically bonded to the inside and the surface of the pores, thereby improving the adhesion between titanium dioxide and the fiber as a photocatalyst, But also the catalytic activity for light in the visible light region is improved and the efficiency of photodecomposing the organic compound remaining in the aqueous solution in the wavelength region of 400 to 800 nm is excellent.

Experimental Example  4.

The following experiment was conducted to evaluate the photocatalytic activity of the photocatalyst according to the present invention whether it is reused or not.

A 500 ml flask was installed in a photoreactor capable of irradiating ultraviolet rays (250 ± 50 nm) and visible light (300 nm to 800 nm, wavelength of irradiated light: 550 ± 20 nm), and a flask was charged with 100 mg / 100 ml of distilled water in which formaldehyde was dissolved was added thereto. Then, 0.1 g of the felt-type photocatalyst prepared in Example 1 was added and the concentration of formaldehyde was measured over time for 3 hours. At this time, the pH of the distilled water in which formaldehyde was dissolved was adjusted to 6 ± 0.5, and the temperature was maintained at 30 ± 1 ° C. When the water treatment was completed, the photocatalyst was taken out from the water treatment liquid, dried, and regenerated by heat treatment at 200 ° C. for 2 hours under a nitrogen gas (N ₂ ) condition. The measured results are shown in Fig.

9, the photocatalyst according to the present invention can be repeatedly used even after regeneration after water treatment, and exhibits a high photocatalytic activity in repeated use. Specifically, the photocatalyst prepared in Example 1 photodecomposed formaldehyde at a high removal rate of 92.0 ± 1% at the time of one-time water treatment, and when it was regenerated and repeatedly subjected to 8-times water treatment, the photocatalyst obtained about 72.2 ± 1% It was confirmed that it had a removal rate of about 70 ± 1%. Since the photocatalyst of the present invention has a structure in which a photocatalyst is physically and chemically bonded to a fibrous support to be fixed, it is preferable to use a photocatalyst containing carbon particles such as activated carbon or a powdery The titanium oxide photocatalyst is superior to the titanium dioxide photocatalyst in terms of structural stability and thus the loss of components having photocatalytic activity during the reuse of the photocatalyst is prevented, which means that the reduction rate of the photocatalytic activity is remarkably low.

Claims (15)

Activated carbon fibers of porous structure; And titanium dioxide which is physically and chemically bonded to the inside and the surface of the pores of the activated carbon fiber and is doped with nickel oxide,
Comprising 30 to 45 parts by weight of carbon, 40 to 64 parts by weight of oxygen, 5 to 15 parts by weight of titanium and 1 to 10 parts by weight of nickel in the analysis of components by energy dispersive X-ray spectroscopy (EDX)
A photocatalyst comprising peaks at 43.6 1 deg., 44.7 1 deg. And 63.2 1 deg. In terms of 2? In X-ray diffraction analysis.
delete The method according to claim 1,
The photocatalyst has an average BET specific surface area of 50 to 200 m < 2 > / g.
delete The method according to claim 1,
And a band gap of 2.4 to 2.6 eV in a wavelength range of 400 nm to 800 nm.
Immersing the activated carbon fibers in a dispersion containing titanium oxide doped with nickel oxide to obtain activated carbon fibers having titanium oxide doped with nickel oxide formed on its surface and pores; And
A process for producing a photocatalyst according to claim 1, comprising the step of heat-treating the activated carbon fiber having titanium oxide doped with nickel oxide on its surface and pores, under an inert gas atmosphere.
The method according to claim 6,
Wherein the heat treatment is carried out in a temperature range of 300 ° C to 600 ° C.
The method according to claim 6,
And the heat treatment time is from 10 minutes to 200 minutes.
Contacting the photocatalyst with an organic compound by contacting an aqueous solution containing an organic compound with a photocatalyst according to claim 1 comprising titanium dioxide doped with nickel oxide and containing activated carbon fibers having a porous structure dispersed in and on pores; And
Irradiating a photocatalyst on which an organic compound is adsorbed to photodegrade the organic compound,
Wherein the light has a wavelength of 200 to 800 nm.
10. The method of claim 9,
Wherein the pH of the aqueous solution containing the organic compound is from 3 to 7.
10. The method of claim 9,
Wherein the aqueous solution containing the organic compound further comprises hydrogen peroxide.
12. The method of claim 11,
Wherein the concentration of hydrogen peroxide is 0.0001 to 0.5% by weight based on the aqueous solution.
10. The method of claim 9,
After the photolysis step,
And a heat treatment step of applying heat to the photocatalyst to regenerate the photocatalyst.
14. The method of claim 13,
Wherein the heat treatment is performed at a temperature ranging from 100 to 300 < 0 > C.
An injection port into which an aqueous solution containing an organic compound is injected;
A filtration unit containing the photocatalyst according to claim 1 for adsorbing an organic compound of an aqueous solution injected from the injection port;
An outlet through which the aqueous solution from which the organic compound has been removed is discharged; And
And a lamp for irradiating light to the filtration unit.

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