KR102608313B1 - Volatile organic compound adsorbent and adsorption filter renewable by light energy, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a composite material for adsorbing volatile organic compounds (VOC) containing titanium dioxide (TiO ₂ ) and activated carbon, a volatile organic compound adsorbent containing the same and regenerative by light energy, an adsorption filter, and a method for manufacturing the same. Since the composite material for adsorbing volatile organic compounds (VOC) according to the invention can easily remove the VOC adsorbed by irradiation of light energy such as ultraviolet rays by introducing titanium dioxide particles into activated carbon, an adsorbent containing the composite material or It not only enables regeneration and reuse of adsorption filters and increases economic efficiency compared to existing VOC adsorbents, but also can expect various effects such as improving the indoor air environment, reducing waste, and protecting the environment.

Description

Volatile organic compound adsorbent, adsorption filter, and method of manufacturing the same that are renewable by light energy

The present invention relates to an adsorbent, an adsorption filter, and a method for manufacturing the same for the removal and/or filtration of volatile organic compounds (VOC).

Absorption, condensation, adsorption, etc. are used as methods to remove volatile organic compounds (VOC) emitted from various industries or daily life.

Among these, adsorption is widely used for VOC removal due to its advantages such as low energy consumption, easy operation, and low process cost.

Since adsorption is achieved by strong friction between the adsorbent material and the surface of the adsorbent, the adsorption performance is determined by the pore structure and surface chemical properties of the adsorbent used. Activated carbon (AC) has a high surface area and high surface activity. It is widely used as an adsorbent.

However, as activated carbon adsorbs VOC, its adsorption capacity gradually decreases, and a high-temperature treatment process is required to regenerate it, which reduces its effectiveness. Therefore, activated carbon filters are saturated with adsorbed VOC and no longer have adsorption performance. Materials are generally not recyclable and are disposed of through landfill or incineration, which causes serious waste of resources and environmental pollution.

Korean Patent Publication No. 10-2010-0127146 (Publication Date: 2010.12.03)

The purpose of the present invention is to provide a volatile organic compound (VOC) adsorbent, an adsorption filter, and a method for manufacturing the same that retain the excellent adsorption performance of activated carbon and at the same time enable recovery of the adsorption performance through a simple method.

In order to achieve the above technical problem, the present invention proposes a composite material for adsorbing volatile organic compounds (VOC) containing titanium dioxide (TiO ₂ ) and activated carbon.

In addition, as an adsorbent based on the composite material for adsorbing volatile organic compounds (VOC), a volatile organic compound (VOC) adsorbent made of activated carbon supported with titanium dioxide (TiO ₂ ) is proposed.

In addition, a method of manufacturing a volatile organic compound (VOC) adsorbent made of activated carbon supported on titanium dioxide (TiO ₂ ), comprising the steps of (A) impregnating activated carbon in a solution containing a titanium dioxide precursor, (B) depositing dioxide on the surface of the activated carbon. Synthesizing titanium to prepare an activated carbon mixture carrying titanium dioxide particles, (C) drying the activated carbon mixture carrying titanium dioxide particles to prepare activated carbon carrying titanium dioxide particles, and (D) preparing activated carbon carrying titanium dioxide particles. We propose a method for manufacturing a volatile organic compound (VOC) adsorbent that includes heat treating activated carbon carrying titanium particles.

In step (A), titanium tetraisopropoxide may be used as the titanium dioxide precursor. When the activated carbon is impregnated with a solution containing a titanium dioxide precursor, the titanium dioxide precursor may be included in an amount of 100 to 1,100 parts by weight based on 100 parts by weight of the activated carbon. If the content of the titanium dioxide precursor is less than 100 parts by weight based on the weight of the activated carbon, it is difficult to expect regeneration of the adsorption performance of activated carbon through titanium dioxide, and if it exceeds 1100 parts by weight, the specific surface area decreases and the adsorption efficiency decreases. .

Additionally, in step (A), the solution containing the titanium dioxide precursor may be prepared by mixing the titanium dioxide precursor with a solvent that does not contain water. The solution containing the titanium dioxide precursor may be preferably prepared by mixing the titanium dioxide precursor with isopropyl alcohol. The titanium dioxide precursor may be mixed to contain 2.6 to 26% by weight based on the total weight of the titanium dioxide precursor-containing solution. The temperature when impregnating the activated carbon with the solution containing the titanium dioxide precursor is preferably room temperature. At this time, room temperature may be 20 to 25°C.

Then, in step (B), distilled water is added to the titanium dioxide precursor solution impregnated with activated carbon, and titanium dioxide is synthesized on the surface of the activated carbon in the solution containing the titanium dioxide precursor to prepare an activated carbon mixture carrying titanium dioxide particles. It is preferable to add 50 to 200 parts by weight of distilled water based on 100 parts by weight of the titanium dioxide precursor into the titanium dioxide precursor solution in which the activated carbon is precipitated. When adding distilled water to the titanium dioxide precursor solution in which the activated carbon has been precipitated, it is preferable to stir it using a magnetic rod and add distilled water drop by drop.

Next, in step (C), the step of drying the activated carbon mixture carrying the titanium dioxide particles is performed by placing the titanium dioxide precursor solution impregnated with the activated carbon in an oven heated to a temperature higher than the boiling point of the solvent that does not contain water. It may include a process of removing the solvent that does not contain water by storing it for 1 to 24 hours. At this time, the activated carbon mixture stored in the oven can be additionally stored in a vacuum oven to completely dry it. Activated carbon can be placed in a vacuum oven, placed under vacuum, and stored at 40°C for 4 hours. The appropriate pressure is 0.01 MPa to 0.02 MPa.

Meanwhile, in step (D), the step of heat treating the activated carbon carrying the titanium dioxide particles in a carbonization furnace is not limited to a specific device, and the temperature increase rate during heating is 1°C/min and the temperature is maintained at 550°C for 2 hours. desirable.

In addition, the present invention is an adsorption filter based on the composite material for adsorbing volatile organic compounds (VOC), characterized in that it is an activated carbon filter coated on the surface with titanium dioxide (TiO ₂ ). suggests.

At this time, the activated carbon filter may have a specific surface area of 80 to 300 m ² /g. And, the average pore size of the activated carbon may be 3 to 40 nm. In addition, the titanium dioxide particles preferably have a size of 200 nanometers to 500 nanometers, but are not necessarily limited thereto.

In addition, a method of manufacturing a volatile organic compound (VOC) adsorption filter consisting of an activated carbon filter coated on the surface with titanium dioxide (TiO ₂ ), comprising the steps of (a) preparing titanium dioxide particles, (b) preparing an adhesive dispersion. Step, (c) preparing a titanium dioxide particle dispersion, (d) spraying the adhesive dispersion and the titanium dioxide particle dispersion on an activated carbon filter, and (e) coating the adhesive dispersion and the titanium dioxide particle dispersion. We propose a method for manufacturing a volatile organic compound (VOC) adsorption filter that includes the step of drying an activated carbon filter.

In step (a), the titanium dioxide particles are prepared by adding distilled water to a solution containing a titanium dioxide precursor. Specifically, titanium tetraisopropoxide can be used as the titanium dioxide precursor. The solution containing the titanium dioxide precursor can be prepared by mixing the titanium dioxide precursor with a solvent that does not contain water to prepare a titanium dioxide mixed solution and then drying the mixture. The solution containing the titanium dioxide precursor may be preferably prepared by mixing the titanium dioxide precursor with isopropyl alcohol. The titanium dioxide precursor may be mixed to contain 18% by weight based on the total weight of the solution containing the titanium dioxide precursor. The temperature when distilled water is added to the solution containing the titanium dioxide precursor is preferably room temperature. At this time, room temperature may be 20 to 25°C.

In addition, the step of drying the titanium dioxide particle mixture is performed by storing the titanium dioxide particle mixture in an oven heated to a temperature higher than the boiling point of the water-free solvent for 8 to 24 hours to dry the water-free solvent. It may include a removal process. At this time, the titanium dioxide particle mixture stored in the oven can be additionally stored in a vacuum oven to completely dry it. Titanium dioxide particles can be placed in a vacuum oven, placed under vacuum, and stored at 40°C for 4 hours, and the appropriate pressure is 0.01 to 0.02 MPa.

Furthermore, the prepared titanium dioxide particles may additionally undergo a heat treatment step in a carbonization furnace, and are not limited to a specific device. The temperature increase rate during heating is preferably 10°C/min, and the temperature is maintained at 550°C for 3 hours.

In step (b), the adhesive may include sodium carboxymethyl cellulose or an aqueous styrene-butadiene copolymer dispersion. The adhesive dispersion can be prepared by diluting the adhesive in an appropriate solvent to reduce viscosity and facilitate spraying. A commercially available spray can be used for spraying.

In step (c), when dispersing titanium dioxide particles in a solvent to prepare a titanium dioxide particle dispersion, anhydrous ethanol can be used as a preferred solvent. This is to allow the titanium dioxide particle dispersion to dry quickly after spraying. The solvent to be used is not limited to this, and a typical solvent that dries quickly due to its high volatility can be used. At this time, titanium dioxide particles may be included in the solvent in an amount of 1 to 10 (weight/volume)%. If titanium dioxide particles are included in the solvent in an amount of less than 1 (weight/volume)%, regeneration of the activated carbon filter cannot be expected because the amount of titanium dioxide particles sprayed on the activated carbon filter is small. In addition, when titanium dioxide particles are included in the solvent in an amount of more than 10 (weight/volume)%, the concentration of the titanium dioxide dispersion increases, making it difficult to spray fine droplets.

And, in step (d), the step of spraying the adhesive dispersion and the titanium dioxide particle dispersion on the activated carbon filter begins with first spraying the adhesive dispersion on the activated carbon filter using a spray. Afterwards, spray the titanium dioxide particle dispersion onto the activated carbon filter as soon as possible before the adhesive dries.

In addition, in step (e), the activated carbon filter coated with the adhesive dispersion and the titanium dioxide particle dispersion is dried using an oven to manufacture a VOC filter made of activated carbon with titanium dioxide particles supported thereon. At this time, a method of drying in an oven heated to 70 ℃ for 30 minutes can be used, but this is not limited to this, and a conventional method of drying all the solvents or solvents used when preparing the adhesive dispersion and titanium dioxide dispersion can be used. Available.

Since the composite material for adsorbing volatile organic compounds (VOC) according to the present invention can easily remove the VOC adsorbed by irradiation of light energy such as ultraviolet rays by introducing titanium dioxide particles into activated carbon, the adsorbent containing the composite material Alternatively, it can enable the regeneration and reuse of adsorption filters, increase economic efficiency compared to existing VOC adsorbents, and various effects can be expected, such as improving the indoor air environment, reducing waste, and protecting the environment.

Figures 1(a) and 1(b) are scanning electron microscope (SEM) photographs of TiO ₂ particles and TiO ₂ -containing activated carbon (AC), respectively.
Figures 2(a) and 2(b) are X-ray photoelectron spectra of the Ti 2p and O 1s regions of TiO ₂ particles, respectively, and Figures 2(c) and 2(d) are respectively This is the X-ray photoelectron spectrum of the Ti 2p and O 1s regions of TiO ₂ -containing activated carbon.
Figures 3(a) and 3(b) are X-ray diffraction patterns of TiO ₂ nanoparticles and TiO ₂ -containing activated carbon, respectively.
Figures 4(a) to 4(c) are N ₂ adsorption/desorption isotherms of TiO ₂ particles, TiO ₂ -containing activated carbon (TiO ₂ /AC), and activated carbon (AC), respectively.
Figure 5(a) shows the results of measuring the adsorption efficiency of TiO ₂ -containing activated carbon (TiO ₂ /AC) according to the number of toluene injections, and Figure 5 (b) shows the results of measuring the adsorption efficiency of TiO ₂ -containing activated carbon (TiO 2 /AC) according to UV-C (15W) exposure time. This is the result of measuring the regeneration rate of TiO ₂ /AC).
Figure 6(a) is the result of measuring the relative concentration change of VOC (toluene and acetaldehyde) after initial adsorption on TiO ₂ -containing activated carbon (TiO ₂ /AC) filter, and Figure 6(b) is the result of measuring the change in relative concentration of VOC (toluene and acetaldehyde) according to light source and exposure time. This is the result of measuring the regeneration rate of a _2- containing activated carbon (TiO ₂ /AC) filter.
Figure 7 is a schematic diagram showing the regeneration mechanism of TiO ₂ -containing carbon material.

In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Since the embodiments according to the concept of the present invention can make various changes and have various forms, specific embodiments will be illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiments according to the concept of the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

The terms used herein are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “include” or “have” are intended to indicate the existence of a described feature, number, step, operation, component, part, or combination thereof, but are not intended to indicate the presence of one or more other features or numbers. It should be understood that this does not preclude the existence or addition of steps, operations, components, parts, or combinations thereof.

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

Embodiments according to the present specification may be modified into various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described in detail below. The embodiments of this specification are provided to more completely explain the present specification to those with average knowledge in the art.

<Example>

1.TiO ₂ synthesis of particles

A mixture of 50 ml isopropyl alcohol (IPA, 99.8%) and 7.4 ml titanium isopropoxide (TTIP, 97%, (Ti[OCH(CH ₃ ) ₂ ] ₄ )) was stirred at room temperature for 5 minutes. To obtain TiO ₂ sol, the mixture was stirred at room temperature at 300 rpm for 1 hour, and then 18 mL of water was added dropwise. The pH of the TiO ₂ sol was adjusted to 7-8 by adding 1M NaOH solution, and then the solution was dried at 100°C overnight. The resulting solid was pulverized and calcined in a furnace at 550°C for 3 hours under N ₂ at a heating rate of 10°C min ^-1 .

2.TiO ₂ /AC synthesis

TTIP (5.74 mL) was added to IPA (40 mL) and the solution was stirred at room temperature for 5 min. After adding 1 g of activated carbon (AC), water (10 mL) was added dropwise to the solution while stirring at room temperature for 1 hour. The resulting gray mixture was dried at 100°C overnight. The resulting solid was pulverized and calcined in a furnace at 550°C for 2 hours under N ₂ at a heating rate of 1°C min ^-1 .

3.TiO ₂ /Production of AC filter

The TiO ₂ particles (1.722 g) synthesized (as-prepared) in 1 above were dispersed in absolute ethanol (20 mL), and the aqueous dispersion (4 mL) of styrene-butadiene copolymer (SB-Latex) was diluted in water (40 mL). TiO ₂ and SB-Latex dispersions were prepared respectively. The diluted SB-Latex dispersion was first sprayed on the AC filter, and then 10 mL of ethanol-TiO ₂ dispersion was sprayed on 50 mg of the AC filter. The resulting TiO ₂ /AC filter was dried at 70°C for 30 minutes.

4.TiO ₂ /VOC adsorption and regeneration of AC and AC filters

To evaluate the adsorption performance of VOCs (toluene and acetaldehyde) on TiO ₂ /AC and TiO ₂ /AC filters, samples were placed in a Tedlar bag (5 L, Gastec, Kanagawa, Japan) and subjected to toluene gas ( 30 ppm in N ₂ ) or acetaldehyde gas (88 ppm in air) was injected. After the Tedler bag was stored in the dark for 30 minutes, the toluene or acetaldehyde concentration inside was measured using a detector tube (122L or 92M, respectively, Gastec). After draining the gas remaining in the Tedler bag, the above process was repeated until the filter was saturated. To regenerate saturated filter samples, the samples were placed in a container filled with air (5 L) for a certain period of time in a dark room illuminated by a UV light source (15 W UV-A or UV-C, Vilber Lourmat, Marne-la-Vallee, France). I stopped by and kept it in my bag. At this time, the distance between the sample and the ultraviolet light source was set to about 15 cm.

<Experimental example>

Figure 1 is an SEM photograph of TiO ₂ particles and TiO ₂ /AC. TiO ₂ particles with a diameter of 200–500 nm were synthesized and successfully attached to AC. Energy-dispersive X-ray spectroscopy showed that the molar ratio of Ti:O was 1:2, confirming the presence of TiO ₂ on the AC surface (Table 1).

<Table 1> TiO ₂ Particles and TiO ₂ Elemental analysis results of activated carbon (AC) containing

^a Field emission scanning electron microscopy (FE-SEM) equipped with an energy-dispersive X-ray spectrometer obtained values for C, Ti, and O, respectively.

X-ray photoelectron spectroscopy (XPS) was performed to analyze the surface chemistry of the material (Figure 2). In the Ti 2p spectrum of TiO ₂ particles (Figures 2(a) and 2(b)), two peaks are observed at 458.6 and 464.3 eV, which correspond to Ti 2p _1/2 and Ti 2p _3/2 of Ti ⁴⁺ , respectively. It applies. In the O 1s spectrum, the O 1s _1/2 peak at 530 eV is assigned to O bound to tetravalent Ti, confirming the presence of TiO ₂ . Additionally, the O 1s _3/2 peak at 531.5 eV is due to the Ti-OH bond on the TiO ₂ surface. XPS of TiO ₂ /AC (FIGS. 2(c) and 2(d)) shows similar peaks at 458.8 and 464.5 eV, respectively, corresponding to Ti 2p _1/2 and Ti 2p _3/2 of Ti ⁴⁺ in the Ti 2p spectrum. indicates. O 1s _1/2 and O 1s _3/2 peaks are observed at 530.1 and 531.8 eV, respectively, again confirming the presence of TiO ₂ and Ti-OH bonds.

To analyze the phase and crystal structure of TiO ₂ , XRD analysis of TiO ₂ particles and TiO ₂ /AC was performed (Figure 3). The diffraction peaks at 2θ = _25.4 °, 37.9°, 48.1°, 54.2°, 54.6°, 62.8°, 70.7°, and 75.4° in the ), (200), (105), (211), (204), (220), and (215) correspond to the crystal planes. On _the other hand, in the Indicates the presence of an image. This difference in crystal phase is believed to be because AC inhibits the TiO ₂ phase change from anatase to rutile. In this example, by coating or spraying TiO ₂ on AC, a larger amount of AC than TiO ₂ is sufficient to suppress the phase change of TiO ₂ to rutile. Therefore, the XRD pattern of TiO ₂ /AC shows only peaks representing anatase, but the XRD pattern of TiO ₂ shows both peaks representing anatase and rutile. The mass fractions of anatase and rutile in TiO ₂ are calculated using the following equations:

where f _A is the mass fraction of anatase in TiO ₂ , K is the correction factor, I _R and I _A are rutile (110) at 2θ = 27° and anatase (101) at 2θ = 25°, respectively. is the strongest XRD peak. The mass fractions of anatase and rutile in TiO ₂ are 0.583 and 0.417, respectively, according to the above equation.

The textural characteristics of TiO ₂ , TiO ₂ /AC and AC were analyzed using N ₂ adsorption. As can be seen in Figure 4(a), the isotherm of TiO ₂ has a low BET (Brunauer-Emmett-Teller) surface area (18.0 m ² g ^-1 ) and shows type II behavior, indicating the non-porous nature of TiO ₂ . However, the isotherms of TiO ₂ /AC and AC show both type I and type IV behavior. TiO ₂ /AC and AC exhibit micropore filling at relatively low pressure (P/P ₀ < 0.2), which is characteristic of type I. TiO ₂ /AC has fewer micropores than AC due to the TiO ₂ clusters covering the surface, so the TiO ₂ /AC isotherm shows a narrow “knee” compared to the AC isotherm. Additionally, the BET surface area of TiO ₂ /AC (409.7 m ² g ^-1 ) is lower than that of AC (930.9 m ² g ^-1 ). The hysteresis loops of the TiO ₂ /AC and AC isotherms shown in Figures 4(b) and 4(c) are characteristic of type IV behavior, with the branches being horizontal and parallel over a wide relative pressure range (P/P ₀ > 0.4). Because it maintains , it is designated as H4 hysteresis. This is a characteristic of the narrow-slit pores inside the AC. In the pore volume and pore diameter distribution curves measured using Barrett, Joyner and Halenda (BJH) analysis, the size range of AC pores is 1.7-6 nm and the average pore diameter is 6.4 nm (Figure 4(c)). In TiO ₂ /AC, the pore size is in the range of 1.7-2.1 nm and the average pore diameter is 5.1 nm, which is smaller than AC. This is because TiO ₂ particles block the pores on the AC surface.

To evaluate the adsorption of TiO ₂ /AC, 50 mg of sample was placed in a Tedlar bag and toluene gas (5 L, 30 ppm in N ₂ ) was injected. Tedler bags were stored in the dark for 5 minutes to allow toluene adsorption. The toluene concentration in the Tedler bag was measured using a detector tube. Adsorption efficiency (E) is calculated as follows.

In the above equation, C _I is the initial concentration of VOC (toluene or acetaldehyde) injected into the Tedlar bag and C _a is the VOC concentration in the Tedlar bag after adsorption.

In order to saturate the adsorption site of TiO ₂ /AC, the process of injecting and removing toluene gas into the Tedler bag was repeated until the toluene concentration reached about 30 ppm (initial concentration of toluene gas) after adsorption in the Tedler bag. . That is, the E of TiO ₂ /AC gradually decreases and reaches almost 0 after repeating the toluene gas injection and removal process several times (FIG. 5a). After the fourth injection, E decreases rapidly, indicating that the adsorption site is almost covered with VOC. The curve shows saturation after the ninth injection. All samples showed saturation curves similar to those shown in Figure 5(a), indicating stable adsorption performance of TiO ₂ /AC. The adsorption capacity of TiO ₂ /AC was estimated by calculating the amount of toluene adsorbed per unit mass of TiO ₂ /AC according to the following equation.

In the above equation, W is the adsorption capacity per unit mass of adsorbent, n is the number of toluene injections, V _T is the volume of the Tedler bag, V _M is the molar volume of the gas at standard temperature and pressure, M _T is the molar mass of toluene, m is is the mass of the adsorbent.

The average W _toluene of TiO ₂ /AC is about 57.4 mg g ^-1 , which is significantly higher than that of other previously reported VOC adsorbents. Although the W of TiO ₂ /AC is reduced compared to AC due to the TiO ₂ particulate coating, it not only exhibits significantly higher values, but also has the distinct advantage of being regenerated through light irradiation.

The dependence of regeneration rate on UV-C exposure time was evaluated using TiO ₂ /AC samples saturated with toluene. Figure 5(b) shows the regeneration rate of TiO ₂ /AC as a function of UV-C exposure time. To regenerate the adsorption sites of TiO ₂ /AC, toluene-saturated TiO ₂ /AC samples were placed in air-filled Tedler bags, and each Tedler bag was exposed to UV-C (15 W, 254 nm) for different times. After UV-C irradiation, the air in the Tedler bag was replaced with toluene (5 L, 30 ppm in air), and the Tedler bag was stored in the dark for 5 minutes. To evaluate the adsorption efficiency (E) after regeneration, the toluene concentration in the Tedler bag was measured, and the regeneration rate ( R ) was calculated as follows.

In the above equation, E _br is the adsorption efficiency before regeneration and E _ar is the adsorption efficiency after regeneration. The R of TiO ₂ /AC after exposure to 15W UV-C for 1 hour is about 50%. Additionally, a rapid increase in R was observed until the exposure time was 4 h, reaching a maximum R (96%) after 12 h.

In order to provide these regenerative properties to commercial AC, TiO ₂ coating was performed by spraying using styrene-butadiene as a binder (TiO ₂ /AC filter). VOC adsorption on the TiO ₂ /AC filter is shown in Figure 6(a), which shows the relative concentration change of VOC (toluene and acetaldehyde) over time after initial adsorption on the TiO ₂ /AC filter. The initial concentrations of toluene and acetaldehyde in air were 18 ppm and 42 ppm, respectively. According to Figure 6(a), the concentration of VOCs (toluene and acetaldehyde) decreases with adsorption time, and adsorption equilibrium is observed at approximately 16 hours. The TiO ₂ /AC filter adsorbs about 50% of acetaldehyde and 80% of toluene for 18 hours, and from this, it can be seen that it shows excellent adsorption performance even when TiO ₂ particles and SB-Latex coat the surface of the AC filter. Figure 6(b) shows the R values of TiO ₂ /AC filters using different light sources for regeneration. The TiO ₂ /AC filter was regenerated using the same method previously described for TiO ₂ /AC regeneration. In this experiment, acetaldehyde (88ppm in air) was used as a VOC gas. The R value of the TiO ₂ /AC filter increases almost linearly with increasing exposure time. After UV-C irradiation for 22 hours, the R of the TiO ₂ /AC filter reached 99%, suggesting that commercial AC filters can be regenerated by spray coating with TiO ₂ particles. To investigate the effect of different types of light sources on R , the same playback process was performed under three conditions: UV-A (15W, 365nm), white LED (100W, 6500K), and no light source (dark room). In each condition, R The values were 22%, 60% and 58%. Therefore, UV-C was confirmed to be the most suitable light source for AC filter regeneration through VOC photolysis by TiO ₂ . However, it is worth noting that easily accessible light sources such as UV-A and white LEDs can also regenerate the filter to some extent.

The photocatalytic regeneration mechanism of TiO ₂ /AC and TiO ₂ /AC filters is shown in Figure 7. AC physically adsorbs VOCs such as toluene and acetaldehyde. When TiO ₂ is exposed to UV-C with a photon energy greater than the bandgap (3.2 eV), electron-hole pairs are generated, and these photogenerated electrons (e ^- ) and holes (h ⁺ ) recombine in the bulk or form TiO ₂ or It can move to the surface of AC and react with O ₂ or H ₂ O. As shown in the formula below, electrons react with O ₂ to generate superoxide radicals (ㆍO ₂ ^- ), and holes react with H ₂ O to generate hydroxyl radicals (ㆍOH) and hydrogen (H ⁺ ).

These radicals react with VOC adsorbed on AC to produce carbon dioxide and water. Therefore, the VOC is decomposed by the photocatalytic activity of the TiO ₂ particles and the TiO ₂ /AC filter is regenerated.

The invention is not limited to the above embodiments, but can be manufactured in a variety of different forms, and those skilled in the art will understand that the invention can be manufactured in other specific forms without changing the technical idea or essential features of the invention. You will understand that it can be done. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

Claims (5)

delete delete delete delete (a) preparing titanium dioxide particles;
(b) preparing an adhesive dispersion consisting of sodium carboxymethylcellulose or styrene-butadiene copolymer aqueous dispersion;
(c) preparing a titanium dioxide particle dispersion;
(d) spraying the adhesive dispersion on an activated carbon filter and then spraying the titanium dioxide particle dispersion on the activated carbon filter; and
(e) drying the activated carbon filter coated with the adhesive dispersion and the titanium dioxide particle dispersion;
A method of manufacturing a volatile organic compound (VOC) adsorption filter comprising a.

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