Floating photocatalyst and method for removing pollutant in water using the same

Abstract

The present invention relates to a floating photocatalyst and a method for removing underwater pollutants using the same. Specifically, it relates to a floating photocatalyst having a fabric form that can float in water, has high photocatalytic efficiency, is easy to use and retrieve, and has excellent durability, and a method for removing underwater pollutants using the same.

Description

Technology Field

[0001] The present invention relates to a floating photocatalyst and a method for removing underwater pollutants using the same. Background Technology

[0002] Physicochemical methods such as adsorption, membrane separation, and oxidation are used to remove underwater pollutants and improve water quality; however, these methods present problems such as incomplete decomposition efficiency and the generation of secondary pollutants. Photocatalysts are semiconducting metal-based materials that can induce the continuous and complete decomposition of underwater pollutants by generating highly reactive oxygen species (ROS) through activation by light energy. Photocatalysts possess a valence band and a conduction band; when exposed to light energy exceeding the band gap energy—the distance between these two bands—electrons in the valence band are excited to the higher energy level of the conduction band, generating electrons and holes. These excited electrons and holes react with surrounding oxygen and water molecules to form highly reactive superoxide anion radicals (O2 -· ) and hydroxyl radicals (OH -· Since photocatalysts generate active oxygen species such as ) and react with water pollutants to cause a series of decomposition reactions that can ultimately break them down into water and carbon dioxide, many studies are being conducted on methods for improving water quality and removing water pollutants using photocatalysts.

[0003] However, since photocatalysts generally exist in powder form, unless a separate stirring and separation device is present, the photoreaction is inefficient due to the powder particles settling into the water, and there is a problem that it is difficult to recover the photocatalyst after use.

[0004] Therefore, for the actual use of photocatalysts to decompose underwater pollutants, the process of introducing the photocatalyst into a substrate, such as a film, is essential. Methods utilizing underwater floating substrates have been studied to solve the problem of reduced light efficiency caused by decreased light transmission in water and to enhance usability. Conventional floating photocatalysts utilize hydrophobic polymers, rocks such as perlite or vermiculite, and cork as substrates for photocatalyst introduction, achieving buoyancy performance based on the hydrophobicity and low density of the materials. However, these hydrophobic materials present problems: the effective introduction of the photocatalyst is very difficult due to hydrophobic functional groups within the polymers, and the low specific gravity causes a portion of the upper portion to be exposed above the water, making it difficult for reactions with harmful substances in the water to occur. These issues lead to low photocatalyst loading amounts and low light efficiency relative to the loading amount, thereby limiting the application of photocatalyst technology for actual water purification. The problem to be solved

[0005] The technical problem that the present invention aims to solve is to provide a floating photocatalyst that can float in water and has high photocatalytic efficiency.

[0006] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0007] One embodiment of the present invention provides a floating photocatalyst comprising a photocatalyst introduction yarn coated with a photocatalyst on its surface; and a specific gravity control yarn that is hydrophobic and has a specific gravity of less than 1, and having a fabric form in which the photocatalyst introduction yarn and the specific gravity control yarn are woven.

[0008] Another embodiment of the present invention provides a method for removing water pollutants, comprising the step of floating a floating photocatalyst according to one embodiment of the present invention in contaminated water. Effects of the invention

[0009] A floating photocatalyst according to one embodiment of the present invention can float without sinking in water and can have high photocatalytic efficiency.

[0010] A floating photocatalyst according to one embodiment of the present invention is easy to use and recover, has excellent durability, and can be reused for a long period of time.

[0011] A method for removing underwater pollutants according to one embodiment of the present invention can effectively remove underwater pollutants, and the method can be simple and economical.

[0012] The effects of the present invention are not limited to those described above, and unmentioned effects will be clearly understood by those skilled in the art from the present specification and the accompanying drawings. Brief explanation of the drawing

[0013] FIG. 1 is a schematic diagram showing the removal of water pollutants using a floating photocatalyst according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the reaction pathway in which a floating photocatalyst according to one embodiment of the present invention decomposes water or dissolved oxygen to generate active oxygen species, and the active oxygen species decompose water pollutants into water and carbon dioxide. Figure 3 is a photograph of the fabric-type floating photocatalyst prepared in Example 1. Figure 4 is a diagram showing SEM images of the carboxymethylated cotton yarn surface (a), UiO@cotton yarn surface (b), and AgI / UiO@cotton yarn surface (c) obtained in the process of Preparation Example 1, and TEM images of the AgI / UiO@cotton yarn (d). Figure 5 is a figure showing the XRD spectra of cotton, UiO@cotton yarn obtained in the process of Preparation Example 1, and AgI-coated cotton yarn (AgI@cotton) obtained using an ion exchange method with AgI / UiO@cotton yarn. Figure 6 is a figure showing the concentration of RhB over time (a) and the first-order reaction rate constant (b) for the RhB removal reaction in a pollutant removal experiment performed under xenon lamp light source conditions and dark conditions using the floating photocatalyst prepared in Example 1. Figure 7 is a diagram showing the concentration of RhB over time in a pollutant removal experiment performed under actual sunlight and darkness conditions using the floating photocatalyst of Example 1. Figure 8 is a diagram showing the floating photocatalyst of Example 1 immediately after being placed in 50 mL of an RhB aqueous solution (10 mg / L) and after being left under direct sunlight for 12 hours. Figure 9 is a photograph of the top and bottom surfaces of the floating photocatalyst recovered after placing the floating photocatalyst of Example 1 in 50 mL of an RhB aqueous solution (10 mg / L) and leaving it under direct sunlight for 12 hours. Figure 10 is a figure showing the concentration of RhB over time in a pollutant removal experiment performed in a side-shielded reactor using the photocatalysts of Example 1 and Comparative Example 1. Specific details for implementing the invention

[0014] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0015] Throughout this specification, when a component is described as being located "on" another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0016] Throughout the entire specification, the unit "parts by weight" may refer to the ratio of weight between each component.

[0017] Throughout this specification, "A and / or B" means "A and B, or A or B".

[0018] Throughout this specification, yarn may mean a thread composed of bundles of fibers.

[0019] Throughout the entire specification, specific gravity expressed as a dimensionless number may mean a relative value of density based on the density of distilled water at 4°C.

[0020] One embodiment of the present invention provides a floating photocatalyst comprising a photocatalyst introduction yarn coated with a photocatalyst on its surface; and a specific gravity control yarn that is hydrophobic and has a specific gravity of less than 1, and having a fabric form in which the photocatalyst introduction yarn and the specific gravity control yarn are woven.

[0021] A floating photocatalyst according to one embodiment of the present invention can decompose water to generate active oxygen species or directly decompose organic matter by receiving light, particularly sunlight.

[0022] Preferably, the floating photocatalyst decomposes water upon receiving sunlight to produce superoxide anion radicals (superoxide radical, O2 -· ) and hydroxyl radicals (OH -· It can generate reactive oxygen species such as ).

[0023] FIG. 1 is a schematic diagram showing the removal of water pollutants using a floating photocatalyst according to one embodiment of the present invention.

[0024] Referring to FIG. 1, a floating photocatalyst according to one embodiment of the present invention has a fabric form in which a photocatalytic yarn and a density control yarn are woven, and can remove water pollutants by photocatalytic activity when floated in water and exposed to sunlight.

[0025] A floating photocatalyst according to one embodiment of the present invention can float without sinking in water and can have high photodecomposition efficiency.

[0026] According to one embodiment of the present invention, the photocatalyst-introducing yarn may mean that a material having photocatalytic activity is coated on the surface of a thread or yarn.

[0027] According to one embodiment of the present invention, the photocatalyst-introducing fiber may comprise a fiber containing a functional group to form a chemical bond with the photocatalyst.

[0028] According to one embodiment of the present invention, the functional group may include one or more selected from the group consisting of a carboxyl group, a hydroxyl group, a carbonyl group, an amino group, a phosphate group, a thiol group, an ester group, an amide group, a urea group, and a halide group, but is not particularly limited thereto.

[0029] Specifically, the photocatalyst-introducing fiber may comprise a cellulose-based fiber, a protein-based fiber, a polyester-based fiber, a polyamide-based fiber, or a combination thereof. When the photocatalyst-introducing fiber comprises a cellulose-based fiber, a protein-based fiber, a polyester-based fiber, a polyamide-based fiber, or a combination thereof, the catalyst loading amount of the photocatalyst-introducing fiber may be high, and furthermore, the durability of the floating photocatalyst containing it may be excellent, allowing for long-term reuse.

[0030] For example, the photocatalyst-introduced fiber may include natural fibers such as cotton fibers, wool fibers, and silk fibers, or synthetic fibers such as viscose rayon, nylon, polyester fibers, and polyurethane fibers.

[0031] According to one embodiment of the present invention, the photocatalyst may include a metal-based material having semiconductor properties.

[0032] According to one embodiment of the present invention, the photocatalyst may include a substance capable of decomposing organic matter or water in response to visible light. Preferably, the photocatalyst may include a substance capable of decomposing water in response to visible light.

[0033] According to one embodiment of the present invention, the metal-based material having semiconductor properties may include one or more of noble metals, metal oxides, metal chalcogenides, metal salts, metal organic frameworks (MOFs), and metal oxides with perovskite structures.

[0034] For example, the photocatalyst is a precious metal such as copper, silver, gold, palladium, platinum, iridium, rhodium, ruthenium, osmium, platinum, and mercury; a metal oxide such as titanium dioxide (TiO2), tungsten trioxide (WO3), vanadium oxide (V2O2), zirconium oxide (ZrO2), and zinc oxide (ZnO); a metal chalcogenide such as zinc sulfide (ZnS), cadmium sulfide (CdS), molybdenum disulfide (MoS2), tungsten selenide (WSe2), and cadmium selenide (CdSe); a metal salt such as silver nitrate (AgNO3), silver fluoride (AgF), and silver iodide (AgI); a MIL-n-type metal-organic framework (MIL, Materials Institute Lavoisier); a UiO-n-type metal-organic framework (UiO, Universitetet i Oslo), It may include one or more metal-organic frameworks such as ZIF-n-type metal-organic frameworks (ZIF, Zeolitic Imidazolate Frameworks) and metal oxides of perovskite structure such as strontium titanate (SrTiO3), but is not particularly limited thereto.

[0035] According to one embodiment of the present invention, the metal-based material having semiconductor properties may be heterojunctioned with two or more types. Specifically, the photocatalyst may be heterojunctioned with a metal-organic framework and a metal salt. By heterojunctioning two or more types of the metal-based material having semiconductor properties, the activity and lifespan of the catalyst may be improved.

[0036] According to one embodiment of the present invention, the photocatalyst may be in the form of nano-sized or micro-sized particles. Since the photocatalyst is in the form of nano-sized or micro-sized particles, the photocatalytic active surface area may be increased, and thus the photocatalytic performance of the floating photocatalyst may be improved.

[0037] According to one embodiment of the present invention, the specific gravity adjusting yarn may mean a yarn that is hydrophobic and has a specific gravity of less than 1.

[0038] According to one embodiment of the present invention, the specific gravity adjusting material has a specific gravity of less than 1. Specifically, the specific gravity adjusting material may have a specific gravity of 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, or 0.9 or less. By satisfying the specific gravity of the specific gravity adjusting material within the above-described range, the floating performance of a floating photocatalyst containing the same may be increased.

[0039] According to one embodiment of the present invention, the specific gravity adjusting material may comprise polypropylene fibers, polyethylene fibers, polyolefin fibers, or a combination thereof. When the specific gravity adjusting material comprises polypropylene fibers, polyethylene fibers, polyolefin fibers, or a combination thereof, the floating photocatalyst comprising it may have excellent floating performance.

[0040] According to one embodiment of the present invention, the photocatalyst introduction yarn included in the floating photocatalyst may be 5 parts by weight or more and 500 parts by weight or less with respect to 100 parts by weight of the specific gravity adjusting yarn.

[0041] The weight ratio between the photocatalyst introduction yarn and the specific gravity adjustment yarn included in the above-mentioned floating photocatalyst can be adjusted according to the specific gravity of the photocatalyst introduction yarn and the specific gravity adjustment yarn and the degree of floating performance to be achieved in the above-mentioned floating photocatalyst.

[0042] According to one embodiment of the present invention, the specific gravity of the photocatalyst-introduced yarn and the specific gravity-regulating yarn may vary depending on the type of fiber included in the photocatalyst-introduced yarn and the specific gravity-regulating yarn, the method of manufacturing the yarn, whether the surface of the yarn is treated, etc.

[0043] The specific gravity of each fiber type is shown in Table 1 below.

[0044] Table 2 below shows the maximum blending ratio of photocatalyst-introduced yarn included in a floating photocatalyst according to one embodiment of the present invention. The ratio of (maximum weight of photocatalyst-introduced yarn capable of realizing floating performance):(weight of specific gravity-adjusting yarn) described in Table 2 is a value calculated based on the theoretical specific gravity value of the fiber described in Table 1 below, when the total specific gravity of the fabric is 1, as the weight ratio of the photocatalyst-introduced yarn and the specific gravity-adjusting yarn.

[0045] Since the specific gravity of the above photocatalyst-introducing yarn and specific gravity-regulating yarn may vary depending on the manufacturing method of the yarn and whether the surface of the yarn is treated, in addition to the conditions of the type of fiber included, the weight ratio of the photocatalyst-introducing yarn and specific gravity-regulating yarn included in the floating photocatalyst according to one embodiment of the present invention may differ from the ratio described in Table 2 below.

[0046] Types of fibers specific gravity noodle 1.54 wool 1.32 dog 1.33~1.45 Viscose rayon 1.50~1.52 nylon 1.14 Polyester 1.38 polyurethane 1.0~1.3 polypropylene 0.91 polyethylene 0.94~0.96

[0048] Example of the blending ratio of photocatalyst-introducing yarn and specific gravity-regulating yarn included in a floating photocatalyst Types of fibers included in photocatalyst introduction yarn Types of fibers included in specific gravity regulators (Maximum weight of photocatalyst-introduced yarn capable of achieving buoyancy):(Weight of specific gravity-adjusting yarn) ratio noodle Polypropylene (based on specific gravity 0.91) Max 0.167:1 Viscose rayon Max 0.173:1 Polyester Max 0.237:1 nylon Max 0.643:1 noodle Polyethylene (based on specific gravity 0.95) Max 0.093:1 Viscose rayon Max 0.096:1 Polyester Max 0.132:1 nylon Max 0.357:1

[0049] According to one embodiment of the present invention, the amount of photocatalyst included in the floating photocatalyst can be maximized by including a photocatalyst introduction agent in the floating photocatalyst at a maximum weight capable of realizing floating performance.

[0050] According to one embodiment of the present invention, the floating photocatalyst can control the degree of floating on water as desired by controlling the floating performance of the fabric-shaped floating photocatalyst by adjusting the ratio of the photocatalyst introduction yarn and the specific gravity control yarn.

[0051] According to one embodiment of the present invention, in order to maximize the effect of removing underwater pollutants by the floating photocatalyst, it may be desirable to control the floating performance of the floating photocatalyst so that the surface of the floating photocatalyst is not exposed above the water surface and remains submerged in water, while simultaneously allowing the floating photocatalyst to float as close as possible to the water surface so that the amount of light reaching the photocatalyst introduction material is maximized.

[0052] A floating photocatalyst according to one embodiment of the present invention has a fabric form in which the photocatalyst introduction yarn and the specific gravity control yarn are woven.

[0053] According to one embodiment of the present invention, the fabric form may be such that the photocatalyst-introducing yarn and the specific gravity-regulating yarn are intertwined with each other as weft and warp yarns.

[0054] According to one embodiment of the present invention, the fabric type may be a plain weave, a twill weave, or a satin weave. Preferably, the fabric type may be a twill weave or a satin weave.

[0055] By making the above fabric type a twill weave or a satin weave, the area of ​​the photocatalyst introduction yarn exposed on one surface of the photocatalyst can be increased.

[0056] According to one embodiment of the present invention, the area of ​​the photocatalyst introduction yarn exposed on one surface of the photocatalyst having a fabric form may be larger than the area of ​​the specific gravity control yarn exposed on one surface of the photocatalyst.

[0057] According to one embodiment of the present invention, it is preferable that the fabric form of the photocatalyst exposes as much of the photocatalyst-introducing yarn as possible on one surface of the photocatalyst. Specifically, if the fabric form is a twill weave or a satin weave, the area where the photocatalyst-introducing yarn is exposed on one surface of the floating photocatalyst in the fabric form can be increased.

[0058] According to one embodiment of the present invention, it may be preferable that one surface of the photocatalyst, in which the exposed area of ​​the photocatalyst introduction material is increased, be used to face the direction in which light is irradiated.

[0059] Another embodiment of the present invention provides a method for removing water pollutants, comprising the step of floating a floating photocatalyst according to one embodiment of the present invention in contaminated water.

[0060] The above contaminated water may refer to water containing contaminants.

[0061] The step of floating the above-mentioned floating photocatalyst in contaminated water does not require a special device or method, and due to the floating ability of the above-mentioned floating photocatalyst, it can be performed by simply placing the fabric-shaped floating photocatalyst into the contaminated water.

[0062] A method for removing underwater pollutants according to one embodiment of the present invention is simple and economical because it can remove pollutants and purify water quality using natural light simply by placing the floating photocatalyst in water containing pollutants. When using natural light, a separate light source may not be required.

[0063] FIG. 2 is a schematic diagram showing the reaction pathway in which a floating photocatalyst according to one embodiment of the present invention decomposes water or dissolved oxygen to generate active oxygen species, and the active oxygen species decompose water pollutants into water and carbon dioxide.

[0064] Referring to FIG. 2, a floating photocatalyst according to one embodiment of the present invention receives light, particularly sunlight, and decomposes water (H2O) or dissolved oxygen (O2) to produce superoxide anion radicals (superoxide radical, O2 -· ) and hydroxyl radicals (OH -· It can decompose water pollutants into water and carbon dioxide by generating active oxygen species such as ), or it can directly decompose water pollutants such as organic matter.

[0065] Preferably, the floating photocatalyst decomposes water upon receiving sunlight to produce superoxide anion radicals (superoxide radical, O2 -· ) and hydroxyl radicals (OH -· It can generate reactive oxygen species such as ). Since reactive oxygen species can react non-selectively with pollutants and decompose them, they can be applied to the removal of various pollutants and can effectively remove pollutants present in trace amounts.

[0066] Specifically, the floating photocatalyst having a fabric form in which the photocatalyst introduction yarn and the specific gravity control yarn are woven can satisfy the condition of being submerged in water without its surface being exposed above the water surface, while simultaneously floating as close as possible to the water surface, so that photocatalytic activity occurs when sunlight is received by the photocatalyst introduction yarn exposed on the upper surface of the floating photocatalyst, and the decomposition of water pollutants can proceed effectively.

[0067] In a method for removing pollutants according to one embodiment of the present invention, the area of ​​the photocatalyst introduction wire exposed on one surface of the photocatalyst is larger than the area of ​​the specific gravity control wire exposed on one surface of the photocatalyst, and the floating photocatalyst may float such that the one surface faces the water surface. Since the area of ​​the photocatalyst introduction wire exposed on one surface of the photocatalyst is larger than the area of ​​the specific gravity control wire exposed on one surface of the photocatalyst, and the floating photocatalyst floats such that the one surface faces the water surface, photocatalytic activity occurs when the photocatalyst introduction wire exposed on the one surface receives sunlight, and the decomposition of water pollutants can proceed more effectively.

[0068] A method for removing underwater pollutants according to one embodiment of the present invention can effectively remove underwater pollutants by using a floating photocatalyst according to one embodiment of the present invention, and since the floating photocatalyst has a fabric form, it is easy to recover after use and has excellent durability, making it economical.

[0069] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0070] Preparation Example 1. Cotton yarn coated with AgI / UiO mixed photocatalyst

[0071] To manufacture cotton yarn coated with an AgI / UiO mixed photocatalyst as a photocatalyst introduction yarn, cotton yarn (0.28 g / m) was used as the base yarn, and UiO-66-NH2(UiO) and silver iodide (AgI) were synthesized in sequence as follows for the photocatalyst coating.

[0072] First, 1 g of cotton yarn was washed in a washing solution at 90°C for 15 minutes to remove impurities and rinsed with distilled water. For the washing solution, 0.24 g of NaOH, 1.2 g of H2O2, and 0.12 g of neutral detergent were dissolved in 120 mL of distilled water.

[0073] To create sites for UiO growth, 1 g of washed cotton yarn was carboxymethylated by immersing it in 100 mL of an aqueous solution containing 9.5 g of chloroacetic acid and 15 g of NaOH. After treatment in the aqueous solution for 72 hours, it was rinsed several times with distilled water.

[0074] UiO was synthesized on the surface of carboxymethylated cotton yarn as described above using the solvothermal method.

[0075] Specifically, as a metal solution, 0.125 g of anhydrous zirconium(IV) chloride (ZrCl4, ≥ 95%, Sigma-Aldrich) was dissolved in a solution of 5 mL of N,N-dimethylformamide (DMF, 99.5%, Daejeong Chemical) and 1 mL of 37% hydrochloric acid (HCl, Daejeong Chemical); then, 90 cm (approx. 0.3 g) of carboxymethylated cotton yarn was immersed in the metal solution and stirred for 10 minutes, during which time the carboxyl groups (-COOH) of the carboxymethylated cotton yarn and Zr 4+ Interactions between ions were induced. Subsequently, a linker solution containing 0.135 g of 2-aminoterephthalic acid (99%, Thermo Fisher Scientific Inc.) in 5 mL of DMF was added to the metal solution in which the cotton yarn was immersed. The mixed solution was stirred for 5 minutes and then placed in an oven at 80°C for 3 hours. The resulting UiO-66-NH2 coated cotton yarn (hereinafter referred to as UiO@cotton yarn) was washed sequentially with DMF, ethanol, and distilled water.

[0076] Next, an ion-exchange method was used to synthesize AgI on the surface of UiO@cotton yarn.

[0077] Specifically, the above UiO@ cotton yarn was immersed in 35 mL of a 0.3 mmol aqueous solution of potassium iodide (KI, 99.5%, Daejeong Chemical) and stirred for 1 hour to promote ionic bonding between Zr ions and I ions of UiO-66-NH2. Subsequently, 3 mL of a 0.1 M silver nitrate (AgNO3, 98-99%, Daejeong Chemical) solution was added dropwise to the KI aqueous solution in which the UiO@ cotton yarn was immersed, and the mixture was reacted for 12 hours to synthesize AgI crystals on the surface of the UiO@ cotton yarn. The obtained AgI / UiO-66-NH2 coated cotton yarn (hereinafter referred to as AgI / UiO@ cotton yarn) was washed several times with distilled water and stored in a constant temperature and humidity chamber (Platinous J, ESPEC, Japan) at 25°C and 50% relative humidity until use.

[0078] Example 1.

[0079] To manufacture a floating photocatalyst in the form of a fabric, a plain weave fabric with a (10 warp)*(13 weft) structure was woven using AgI / UiO@ cotton yarn, which is the photocatalyst introduction yarn prepared in Preparation Example 1, as the weft yarn, and polypropylene yarn (0.5 g / m) as the specific gravity adjustment yarn as the warp yarn. The woven fabric was cut to a size of 2.5 cm x 2 cm and used as an experimental sample. At this time, the experimental sample contained approximately 0.12 g of polypropylene yarn and 0.25 g of AgI / UiO@ cotton yarn; therefore, the photocatalyst introduction yarn contained in the fabric was approximately 203 parts by weight per 100 parts by weight of the specific gravity adjustment yarn.

[0080] Figure 3 is a photograph of the fabric-type floating photocatalyst prepared in Example 1.

[0081] Comparative Example 1. (Suberged sample)

[0082] A photocatalyst in the form of a fabric was prepared in the same manner as in Example 1, except that the photocatalyst-introducing yarn AgI / UiO@cotton yarn prepared in Preparation Example 1 was used as the weft yarn, and polypropylene yarn (0.5 g / m) was used as the specific gravity-regulating yarn as the warp yarn to weave a plain weave fabric with a (2 warp)*(13 weft) structure. At this time, the experimental sample contained approximately 0.024 g of polypropylene yarn and 0.25 g of AgI / UiO@cotton yarn, and thus the photocatalyst-introducing yarn contained in the fabric was approximately 1042 parts by weight per 100 parts by weight of the specific gravity-regulating yarn.

[0083] Experimental Example 1: Confirmation of a photocatalyst-introducing yarn coated with a photocatalyst on its surface

[0084] SEM and TEM images were obtained for the cotton yarn coated with the AgI / UiO mixed photocatalyst prepared in Preparation Example 1 using a field emission scanning electron microscope (FE-SEM, JSM-7800F Prim, JEOL Ltd., Japan) equipped with an energy dispersive X-ray spectrometer (EDS).

[0085] Figure 4 is a diagram showing SEM images of the carboxymethylated cotton yarn surface (a), UiO@cotton yarn surface (b), and AgI / UiO@cotton yarn surface (c) obtained in the process of Preparation Example 1, and TEM images of the AgI / UiO@cotton yarn (d).

[0086] Referring to Fig. 4, it was confirmed that the AgI / UiO@cotton yarn prepared in Preparation Example 1 has a layered structure in which a UiO layer is coated on the surface of the cotton fiber and AgI nanoparticles are formed on the surface of the UiO.

[0087] Furthermore, to confirm the crystal structure of the mixed photocatalyst in the cotton yarn coated with the AgI / UiO mixed photocatalyst prepared in Preparation Example 1, XRD analysis was performed using an X-ray diffraction analyzer (XRD, SmartLab, Rigaku, Japan).

[0088] Figure 5 is a figure showing the XRD spectra of cotton, UiO@cotton yarn obtained in the process of Preparation Example 1, and AgI-coated cotton yarn (AgI@cotton) obtained using an ion exchange method with AgI / UiO@cotton yarn.

[0089] Referring to Fig. 5, peaks corresponding to UiO and AgI were observed in the AgI / UiO@cotton yarn prepared in Preparation Example 1, confirming that the AgI / UiO mixed photocatalyst contains UiO crystal structure and AgI crystal structure.

[0090] Experimental Example 2. Experiment on pollutant removal using a floating photocatalyst

[0091] Rhodamine B (RhB, Seoul Chemical), a dye molecule, was selected as the experimental contaminant, and the experiment was conducted using 50 mL of an RhB aqueous solution (10 mg / L). To verify photocatalytic activity under visible light, a UV blocking filter (> 400 nm, 100 mW / cm²) was used. 2 A 150W xenon lamp equipped with ) was used as a light source.

[0092] The floating photocatalytic fabric prepared in Example 1 was floated on an RhB aqueous solution without a prior adsorption step. The experiment was conducted for 2 hours each under the xenon lamp light source and in the dark without a light source while stirring the RhB aqueous solution, and 0.6 mL of the solution was extracted every 20 minutes to measure the RhB concentration.

[0093] The concentration of the RhB solution was measured by UV-vis absorbance spectroscopy (Synergy H1, BioTek, USA) at a wavelength of 553 nm, and the first-order reaction rate constant of the RhB removal reaction was calculated using the following equation (1).

[0094] (1) -ln(C / C0)= kt (C is the RhB concentration at t, and C0 is the RhB concentration at t=0.)

[0095] Figure 6 is a figure showing the concentration of RhB over time (a) and the first-order reaction rate constant (b) for the RhB removal reaction in a pollutant removal experiment performed under xenon lamp light source conditions and dark conditions using the floating photocatalyst prepared in Example 1.

[0096] Referring to Figure 6, even under dark conditions without a light source, the floating photocatalyst of Example 1 removed up to about 65% of RhB through adsorption after 2 hours, confirming that there is some RhB removal effect through adsorption. Under a xenon lamp light source, the floating photocatalyst of Example 1 removed up to about 98% of RhB through adsorption and photodecomposition due to photocatalytic activity after 2 hours, confirming that the pollutant removal performance is excellent.

[0097] Experimental Example 3: Experiment on the Removal of Underwater Pollutants Under Actual Sunlight

[0098] Furthermore, to simulate the application of the floating photocatalyst according to the present invention to water purification under actual sunlight, an experiment to remove water pollutants was conducted outdoors. Specifically, the floating photocatalyst fabric prepared in Example 1 was placed in 50 mL of an RhB aqueous solution (10 mg / L) and left under direct sunlight from 10:00 AM to 5:00 PM without any operation such as stirring, and 0.6 mL of the solution was extracted every hour to measure the RhB concentration. To obtain accurate experimental results, the experiment was repeated on three different days.

[0099] In addition, the RhB aqueous solution in which the floating photocatalytic fabric of Example 1 was floating was left for the same amount of time even under dark conditions without a light source.

[0100] Figure 7 is a diagram showing the concentration of RhB over time in a pollutant removal experiment performed under actual sunlight and darkness conditions using the floating photocatalyst of Example 1.

[0101] Referring to Fig. 7, it was confirmed that the floating photocatalyst of Example 1 exhibited an RhB removal efficiency of about 55% to 70% (based on 7 hours of standing) even under actual sunlight conditions, and it was confirmed that the floating photocatalyst according to one embodiment of the present invention can effectively remove water pollutants through photodecomposition by simply floating it in water containing pollutants without complex operation.

[0102] Figure 8 is a diagram showing the floating photocatalyst of Example 1 immediately after being placed in 50 mL of an RhB aqueous solution (10 mg / L) and after being left under direct sunlight for 12 hours.

[0103] Referring to Fig. 8, it can be seen that the floating photocatalyst of Example 1 floats well near the surface of the aqueous solution. When left under direct sunlight for 12 hours, the effect of removing contaminants was directly confirmed by the fact that RhB was removed and the solution became transparent. It was also confirmed that the floating photocatalyst has excellent durability as there was no change in its appearance or floating performance.

[0104] Figure 9 is a photograph of the top and bottom surfaces of the floating photocatalyst recovered after placing the floating photocatalyst of Example 1 in 50 mL of an RhB aqueous solution (10 mg / L) and leaving it under direct sunlight for 12 hours.

[0105] Referring to Figure 9, the upper surface of the floating photocatalyst, which can receive visible light, showed that the RhB adsorbed on the thread was almost completely decomposed and the color returned to its original state, whereas the lower surface of the floating photocatalyst, which cannot receive visible light, did not have photocatalytic activity and showed an appearance stained with RhB.

[0106] To analyze the effect of the floating characteristics of the photocatalyst on the pollutant removal effect, 10 mL of an RhB aqueous solution (10 mg / L) was filled into a narrow cylindrical reactor with shielded sides, and the floating photocatalyst of Example 1 and the photocatalyst of Comparative Example 1 were each placed in the RhB aqueous solution to perform a water pollutant removal experiment under sunlight. The RhB aqueous solutions containing the floating photocatalyst of Example 1 and the photocatalyst of Comparative Example 1 were left under direct sunlight from 10:00 AM to 5:00 PM without any operation such as stirring, and 0.6 mL of the solution was extracted every 2 hours starting from 11:00 AM to measure the RhB concentration.

[0107] At this time, it was confirmed that the fabric-type photocatalyst prepared in Comparative Example 1 settled at the bottom of the RhB aqueous solution, and the height difference between the floating photocatalyst of Example 1 floating in the RhB aqueous solution and the photocatalyst of Comparative Example 1 that settled was approximately 15 cm.

[0108] Figure 10 is a figure showing the concentration of RhB over time in a pollutant removal experiment performed in a side-shielded reactor using the photocatalysts of Example 1 and Comparative Example 1.

[0109] Referring to Fig. 10, the photocatalyst of Comparative Example 1 showed an RhB removal efficiency of only about 12% when left under direct sunlight for 8 hours in a side-shielded reactor, and it was confirmed that the photodecomposition effect was reduced because the photocatalyst of Comparative Example 1 did not possess buoyancy performance and sank in the water. On the other hand, the floating photocatalyst of Example 1 showed an RhB removal efficiency of about 33% when left under direct sunlight for 8 hours in a side-shielded reactor, and through this, it was confirmed that the photocatalyst according to the present invention, which possesses buoyancy performance, is much more effective in removing water pollutants through photodecomposition.

[0110] Although the present invention has been described above by limited embodiments, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

Claims

Claim 1 A floating photocatalyst comprising: a photocatalyst introduction yarn coated with a photocatalyst on its surface; and a specific gravity control yarn that is hydrophobic and has a specific gravity of less than 1, wherein the photocatalyst is heterojunctioned with a metal-organic framework and a metal salt, and the photocatalyst introduction yarn comprises a fiber containing a functional group that forms a chemical bond with the photocatalyst, and the photocatalyst introduction yarn and the specific gravity control yarn are woven into a fabric form. Claim 2 A floating photocatalyst according to claim 1, wherein the photocatalyst-introducing fiber comprises a cellulose-based fiber, a protein-based fiber, a polyester-based fiber, a polyamide-based fiber, or a combination thereof. Claim 3 A floating photocatalyst according to claim 1, wherein the specific gravity adjusting fiber comprises polypropylene fiber, polyethylene fiber, polyolefin fiber, or a combination thereof. Claim 4 delete Claim 5 delete Claim 6 A floating photocatalyst according to claim 1, wherein the photocatalyst introducing yarn is included in an amount of 5 parts by weight or more and 500 parts by weight or less per 100 parts by weight of the specific gravity adjusting yarn. Claim 7 A floating photocatalyst according to claim 1, wherein the fabric form is a twill weave or a satin weave. Claim 8 A floating photocatalyst according to claim 1, wherein the area of ​​the photocatalyst introduction wire exposed on one surface of the photocatalyst is larger than the area of ​​the specific gravity control wire exposed on one surface of the photocatalyst. Claim 9 A method for removing underwater pollutants comprising the step of floating a floating photocatalyst according to claim 1 in contaminated water. Claim 10 A method for removing pollutants according to claim 9, wherein the area of ​​the photocatalyst introduction wire exposed on one surface of the photocatalyst is larger than the area of ​​the specific gravity control wire exposed on one surface of the photocatalyst, and the floating photocatalyst floats such that the one surface faces the water surface.

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