Photocatalytic composition, its manufacturing method, and deodorant

Abstract

Provided is an inexpensive photocatalyst composition which can be used for the decomposition or sterilization of an organic substance, which is not limited in terms of uses, which allows impacts on the human body and the environment to be suppressed, and which exhibits excellent photocatalytic activity in a wide range of wavelengths including that of visible light.　This photocatalyst composition exhibits catalytic activity with visible light and contains a glass material, an iron-supplying raw material, and a reducing organic substance that has the effect of reducing trivalent iron to bivalent iron. The reducing organic substance contains a polyphenol and / or ascorbic acid, and the iron-supplying raw material contains a bivalent iron compound and / or a trivalent iron compound.

Description

[Technical Field]

[0001] The present disclosure relates to a photocatalytic composition that exhibits photocatalytic activity in response to visible light, a method for producing the same, and a deodorant. [Background technology]

[0002] In recent years, contamination caused by harmful microorganisms such as viruses (such as the new coronavirus, avian influenza virus, and swine fever virus) and pathogenic E. coli (such as O-157) has become a social problem around the world. Photocatalysis has attracted attention as one of the sterilization technologies for such harmful microorganisms. Photocatalysis can be used to decompose and sterilize organic hazardous substances simply by irradiating them with light, and there is growing social demand for this simple and versatile technology.

[0003] In addition to titanium oxide, metal compounds such as those containing tungsten, indium, vanadium, silver, molybdenum, zinc, gallium phosphide, gallium, and arsenic are known to exhibit photocatalytic activity. However, most of these metal compounds are very expensive and highly toxic, preventing their practical application. Currently, titanium oxide is the only metal compound in practical use as a photocatalyst. Furthermore, all of these metal compounds exhibit photocatalytic activity only at ultraviolet wavelengths of 400 nm or less, making them unsuitable for sterilization and decomposition in living spaces where only visible light, such as fluorescent lamps, can be used, limiting their application.

[0004] In addition, attempts have been made to incorporate impurities (doping) to achieve photocatalytic activity under visible light, but the processing technology is difficult, making the product very expensive, and it is not possible to obtain sufficient photocatalytic activity under visible light, so no such technology has yet been put to practical use.

[0005] On the other hand, the development of photocatalysts centered on polyphenol iron complexes has also been carried out (see, for example, Patent Document 1). Since the photocatalyst described in this Patent Document 1 absorbs light with a wide range of wavelengths including visible light and exhibits activity, the range of applications can be expanded. In addition, since it does not use rare metals and uses plants or their processed products as raw materials, it has little impact on the human body and the environment and can provide photocatalysts at a low cost. In addition, in order to improve the durability of the photocatalyst and enable stable photocatalytic activity, the invention of photocatalytic glass containing an iron component has also been disclosed (see Patent Documents 2 and 3).

[0006] Under the above circumstances, the development of an inexpensive photocatalyst that is not limited in the application scene, can suppress the impact on the human body and the environment, and exhibits excellent photocatalytic activity with visible light has been expected.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention solves the above problems, can be used for organic matter decomposition or sterilization, is not limited in the application scene, can suppress the impact on the human body and the environment, and exhibits excellent photocatalytic activity with respect to light with a wide range of wavelengths including visible light, and aims to provide a photocatalyst composition at a low cost.

Means for Solving the Problems

[0009] After extensive research, the inventors discovered that a polyphenol-iron complex obtained by mixing polyphenols and an iron source in the presence of water exhibits photocatalytic activity not only with ultraviolet light but also with visible light and infrared light. Furthermore, the inventors believed that bonding carbon and divalent iron in the polyphenol-iron complex would increase the stability of the polyphenol-iron complex and produce a stable photocatalyst. As a result of investigating reactions under various conditions, they discovered that when glass was produced using polyphenols and an iron source, excellent photocatalytic activity could be maintained and the stability of the photocatalyst could be improved.

[0010] The present disclosure has been made based on these findings. That is, the photocatalytic composition according to the present disclosure is a photocatalytic composition that exhibits catalytic activity under visible light, and contains a reductive organic substance that has the effect of reducing trivalent iron to divalent iron, an iron supplying material, and a glass material, wherein the reductive organic substance contains at least one of polyphenols and ascorbic acid, and the iron supplying material contains at least one of a divalent iron compound and a trivalent iron compound. Furthermore, the deodorant according to the present disclosure contains the above-mentioned photocatalyst composition that exhibits catalytic activity when exposed to visible light. Furthermore, the method for producing a photocatalytic composition according to the present disclosure is a method for producing a photocatalytic composition that exhibits catalytic activity when exposed to visible light as described above, and includes a step of heat-treating the reductive organic substance having the ability to reduce trivalent iron to divalent iron, the iron supply raw material, and the glass material in a reducing atmosphere at a heating temperature of 900°C or higher for a heating time of 12 minutes or longer. [Effects of the Invention]

[0011] The photocatalytic composition of the present disclosure exhibits activity not only when irradiated with ultraviolet light but also when irradiated with visible light or infrared light, making it possible to use it in ordinary indoor spaces, etc. Furthermore, because it uses polyphenols and ascorbic acid as raw materials for the iron-reducing organic substance, the photocatalyst of the present disclosure can reduce its impact on the human body and the environment. This makes it possible to use the photocatalytic composition of the present disclosure in a variety of applications that were difficult to achieve with titanium oxide of the prior art.

[0012] Therefore, it is possible to provide a photocatalytic composition at low cost that can be used for decomposing or sterilizing organic matter, is not limited to certain application situations, has minimal impact on the human body and the environment, and exhibits excellent photocatalytic activity over a wide range of wavelengths including visible light. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a flowchart showing an example of a manufacturing process for a photocatalytic composition according to an embodiment of the present invention. [Figure 2] 1A and 1B are photographic images for explaining the photocatalytic composition of Example 1, in which (a) shows a photographic image of the photocatalytic composition of Example 1 (plate glass) before crushing, (b) shows a photographic image of the photocatalytic composition of Example 1 (powdered glass) after crushing, and (c) shows a photographic image of the photocatalytic composition of Example 1 after crushing in (b) stained with dipyridyl. [Figure 3] This is the spectral distribution of the white LED light used in the experimental example. [Figure 4] 1A and 1B are diagrams for explaining the decomposition effect of harmful substances by the photocatalytic composition when irradiated with white LED light, in which (a) is a graph showing the results of an experiment to verify the decomposition effect, (b) is a photograph of the solution in the control group using titanium oxide, and (c) is a photograph of the solution in the group irradiated with white LED light using the photocatalytic composition of Example 1. [Figure 5] Photographs illustrating the decomposition effect of harmful substances by the photocatalytic composition when irradiated with ultraviolet light, where (a) shows a photograph of the solution in the control group, (b) shows a photograph of the solution in the ultraviolet-irradiated group using the photocatalytic composition of Example 1, and (c) shows a photograph of the solution in the titanium oxide group using titanium oxide. [Figure 6] Photographs illustrating the decomposition effect of harmful substances by the photocatalytic composition when irradiated with ultraviolet light, where (a) shows a photograph of the solution in the control group (without photocatalyst), (b) shows a photograph of the solution in the titanium oxide group using titanium oxide, and (c) shows a photograph of the solution in the near-infrared irradiated group using the photocatalytic composition of Example 1. [Figure 7]1A and 1B are photographs illustrating the bactericidal effect of the photocatalytic composition of Example 1 on Escherichia coli, in which (a) shows a photograph of the control group treated with light irradiation only, (b) shows a photograph of the control group treated with the photocatalytic composition in the dark, and (c) shows a photograph of the control group treated with white LED light using the photocatalytic composition. [Figure 8] 1A and 1B are diagrams illustrating the sterilization effect of the photocatalyst composition of Example 1 on E. coli, where (a) shows the results of determining whether E. coli is viable or dead in the "dark condition group" using the photocatalyst composition as a control group, and (b) shows the results of determining whether E. coli is viable or dead in the "white LED light irradiation group" using the photocatalyst composition. [Figure 9] 1A and 1B are diagrams illustrating the bactericidal effect of the photocatalyst composition of Example 1 on the bacterial wilt disease bacteria, where (a) shows the results of determining whether the bacterial wilt disease bacteria are alive or dead in the "dark condition area" where the photocatalyst composition was used as a control, and (b) shows the results of determining whether the bacterial wilt disease bacteria are alive or dead in the "white LED light irradiation area" where the photocatalyst composition was used. [Figure 10] FIG. 1 shows the results of an experiment to identify radical species by luminol reaction in the photocatalytic composition of Example 1. [Figure 11] FIG. 1 shows the results of an experiment to identify superoxide radicals using the MPEC reagent of the photocatalytic composition of Example 1. [Figure 12] FIG. 1 is a diagram showing the results of measuring the ESR spectrum when the photocatalytic composition of Example 1 is irradiated with ultraviolet LED light. [Figure 13] FIG. 1 is a diagram showing the results of ESR analysis of the photocatalytic composition of Example 1 irradiated with white LED light (visible light). [Figure 14] 1A and 1B are photographs illustrating the effect of the photocatalytic composition of Example 2 on maintaining the freshness of cut flowers (camellias), where (a) is a photograph showing the state of irradiation with white LED light, (b) is a photograph of the light-irradiated area 10 days after the start of the experiment, and (c) is a photograph of the control area 10 days after the start of the experiment. [Figure 15]Photographs illustrating the freshness-preserving effect of the photocatalytic composition of Example 2 on another different cut flower (Saponaria vaccaria), where (a) is a photograph of the white LED light irradiation area at the start of the experiment and the control area, and (b) is a photograph of the white LED light irradiation area and the control area three days after the start of the experiment. [Figure 16] 1A and 1B are photographs illustrating the sterilization effect of the photocatalytic composition of Example 2 on seeds, where (a) shows a photograph of the control area 7 days after the start of the experiment, and (b) shows a photograph of the light-irradiated area 7 days after the start of the experiment. [Figure 17] 1A and 1B are photographs illustrating the sterilization effect of the photocatalytic composition of Example 2 on seeds (sterilization effect on germs), where (a) shows a photograph of the proliferation of germs in chickpeas in the control group, and (b) shows a photograph of the proliferation of germs in chickpeas in the ultraviolet LED light irradiation group. [Figure 18] FIG. 1 is a diagram showing the steps of extracting silica from diatoms in Examples 5 and 6. [Figure 19] 10A and 10B are diagrams for explaining the decomposition effect of harmful substances by the photocatalytic composition of Example 5, in which (a) shows a graph illustrating the results of an experiment to verify the decomposition effect, and (b) shows photographs of the solution in the LED light irradiation area and the control area 4 hours after the start of the experiment. [Figure 20] 10A and 10B are diagrams for explaining the decomposition effect of harmful substances by the photocatalytic composition of Example 6, in which (a) shows a graph illustrating the results of an experiment to verify the decomposition effect, and (b) shows photographs of the solution in the LED light irradiation area and the control area 4 hours after the start of the experiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail. (Photocatalyst composition) The photocatalytic composition according to the present embodiment is a photocatalytic composition that exhibits catalytic activity under visible light and contains a reducing organic substance that reduces trivalent iron to divalent iron, an iron supplying material, and a glass material. The photocatalytic composition according to the present embodiment is preferably a photocatalytic glass or a photocatalytic glass ceramic. The iron supplying material contains at least one of a divalent iron compound and a trivalent iron compound, and the reducing organic substance is at least one of a polyphenol and ascorbic acid.

[0015] [Reduced organic matter] The photocatalytic composition of this embodiment uses a "reducing organic substance that has the ability to reduce trivalent iron to divalent iron" as a raw material that supplies carbon. Hereinafter, this "reducing organic substance that has the ability to reduce trivalent iron to divalent iron" may be referred to as a "reducing organic substance with iron-reducing ability" or simply as a "reducing organic substance."

[0016] Specific examples of such reducing organic substances include ascorbic acid, polyphenols, etc. In addition to these compounds, plants or their processed products may contain many reducing organic substances that have iron-reducing ability, and these can be suitably used as reducing organic substances.

[0017] Here, as "ascorbic acid", not only free ascorbic acid but also ascorbic acid compounds (potassium ascorbate, sodium ascorbate, etc.) can be used.

[0018] "Polyphenols" is a general term for phenolic molecules with multiple hydroxyl groups. Polyphenols are compounds found in most plants, and various types are known, including flavonoids and phenolic acids. Specific examples of polyphenol compounds include catechins (epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate, etc.), tannic acid, tannins, chlorogenic acid, caffeic acid, neochlorogenic acid, cyanidin, proanthocyanidin, thearubigin, rutin, flavonoids (quercitrin, anthocyanins, flavanones, flavanols, flavonols, isoflavones, etc.), flavones, chalcones (naringenin chalcone, etc.), xanthophyll, carnosic acid, eriocitrin, nobiletin, tangeretin, magnolol, honokiol, ellagic acid, lignans, curcumin, coumarin, catechol, procyanidins, theaflavin, rosmarinic acid, xanthone, quercetin, resveratrol, gallic acid, and phlorotannin. Also included are compounds having one or more of these compounds in the molecule (for example, polymerized complexes containing these compounds bound together).

[0019] In addition, polyphenol compositions extracted from certain fruits are sometimes referred to as "polyphenols" after the name of the fruit. For example, a polyphenol composition extracted from grapes is called grape polyphenols. In addition, in this embodiment, when a purified product of the above-mentioned compound is used as a raw material for the reducing organic matter, the activity of the photocatalyst is enhanced, which is preferable.

[0020] · Feedstock for reducing organic matter In this embodiment, a plant or a processed product thereof containing at least one of polyphenols and ascorbic acid can be used as a source of reducing organic matter. The plant may be derived from one or more parts selected from the group consisting of fruits, seeds, stems, leaves, buds, flowers, roots, and rhizomes.

[0021] Examples of plant materials that contain a lot of ascorbic acid include tomatoes, bell peppers, chili peppers, winter melon, bitter melon, zucchini, cucumbers, snow peas, pumpkins, eggplants, green peas, broad beans, edamame beans, okra, acerola, citrus fruits (lemon, lime, orange, grapefruit, navel orange, yuzu, kumquat, kabosu, summer mandarin orange, hassaku citrus, iyokan, lime, Satsuma mandarin, Shikuwasa, mandolin, etc.), persimmons, kiwifruit, papaya, blackberries, blueberries, cranberries, raspberries, bilberries, huckleberries, strawberries, melons, apples, pears, pears, figs, peaches, plums, guava, grapes, prunes, Akebia japonica, and daikon radishes. These include peaches, pineapples, mangoes, bananas, cherries, pomegranates, watermelons, gummi candies, loquats, black currants, chestnuts, lychees, ginkgo nuts, olives, avocados, tea, lettuce, cabbage, kale, mustard greens, mizuna, komatsuna, daikon radish, turnips, rape blossoms, Chinese cabbage, bok choy, takana, nozawana, mulukhiyah, green onions, wild garlic, garlic, scallions, chives, onions, shallots, shiso, angelica tree, morning glory, watercress, asparagus, basil, parsley, parsley, spinach, chrysanthemums, bamboo shoots, broccoli, cauliflower, sweet potatoes, potatoes, mountain yams, lotus root, turnips, daikon radishes, Brussels sprouts, and seaweed (nori, wakame, kelp, sea lettuce, etc.).

[0022] In addition, examples of plant raw materials that contain a lot of polyphenols include herbs (lavender, mint, coriander, cumin, sage, lemongrass, mugwort, comfrey, shiso, lemon balm, oregano, catnip, common thyme, dill, dark opal, basil, hyssop, peppermint, lamb's ear, etc.), Houttuynia cordata, marigold, grapes, coffee (coffee tree), tea (Camellia sinensis), cacao, acacia, cedar, pine, sugarcane, mango, banana, papaya, avocado, apple, cherry, guava, olive, potatoes (sweet potato, etc.). Sweet potato, purple sweet potato (sweet potato with a high purple pigment content), potato, mountain yam, taro (coroaming yam, shrimp potato, etc.), konjac, etc.), persimmon, mulberry, blueberry, poplar, ginkgo, chrysanthemum, sunflower, bamboo, citrus fruits (lemon, lime, orange, grapefruit, navel orange, yuzu, kumquat, kabosu, summer mandarin, hassaku, iyokan, lime, Satsuma mandarin, Shikuwasa, mandarin, etc.), strawberry, blackberry, cranberry, raspberry, bilberry, huckleberry, plum, peach, plum, pear, European pear, loquat, kiwi Fruits, mangosteen, shishito peppers, prunes, melons, dragon fruit, wolfberries, black currants, cashews, viburnum, pomegranates, acai, aronia, eggplant, tomatoes, soybeans, black soybeans, adzuki beans, green beans, peanuts, black sesame seeds, buckwheat, tartary buckwheat, sesame seeds, purple cabbage, sumac, water chestnut, crown daisy, broccoli, spinach, komatsuna, mitsuba, okra, butterbur, onions, mulukhiyah, crown daisy, garlic, purple onions, asparagus, parsley, eucalyptus, udo, gymnema sylvestre, senna, dandelions, horsetail, ferns (bracken, fern, etc.), oak, kudzu Oak, maple, redwood, metasequoia, cypress, Mallotus japonicus, takanotsume, amacha, Akebia, Japanese angelica, Japanese angelica, Cleistocene, Japanese zelkova, Magnolia, Magnolia japonica, Kobushi, Argus arvensis, White mulberry, Japanese spicebush, Japanese spicebush, Japanese holly, Cladophora arvensis, Magnolia obovata, Actinidia chinensis, Banaba, Rooibos, Rahma, Kudzu, Japanese bead tree, Lithospermum liliiflora, Brassica rapa, Melinjo, Cherry, Magnolia, Yerba mate, Kandelia candel, Bruguiera gigantea, Rhizophora gracilis, Sea pomegranate, Nipa palm, Avicennia marina, Mangrove, Heronia japonica, Burdock, Turmeric, Lotus root, Seaweed (nori, wakame, kelp,Examples include sea lettuce, sea lettuce, and sea lettuce.

[0023] Among these, grapes, coffee (coffee tree), tea (Camellia sinensis), cacao, acacia, cedar, pine, yuzu, lemon, herbs (lavender, mint, coriander, cumin, sage, shiso, lemongrass, mugwort, comfrey, lemon balm, oregano, catnip, common thyme, dill, dark opal, basil, hyssop, peppermint, lamb's ear, etc.), Houttuynia cordata, marigold, sugarcane, mango, banana, papaya, avocado, apple, cherry, guava, olive, potatoes (sweet potato, purple potato (sweet potato containing a lot of purple pigment), potato, yam, taro (coroa, ebiimo, etc.), konjac, etc.), persimmon, mulberry, blueberry, poplar, ginkgo, chrysanthemum, sunflower, and bamboo are preferably used.

[0024] Examples of "processed products" include dried products, squeezed juices, extracts, and extracts of plants containing polyphenols and ascorbic acid. In addition, squeezed juices and extracts may be further dried.

[0025] The "dried material" is preferably one that has been crushed, pulverized, powdered, etc. Furthermore, in consideration of the reaction efficiency with iron, a powder with a small particle size is preferable. As the extraction solvent for the "extract" and "extraction liquid," water is suitable for ascorbic acid, and water, hot water, alcohol (particularly ethanol), and aqueous alcohol (particularly aqueous ethanol) are suitable for polyphenols.

[0026] As a source of reducing organic matter, the residue obtained by extracting a plant or its processed product with water or hot water can be suitably used. In addition, a dry distillation liquid (plant dry distillation liquid) obtained by thermally decomposing a plant or its processed product under reducing conditions can also be suitably used.

[0027] Plant-derived raw materials with cost advantages In this embodiment, by using fruit juice, stem and leaf juice, plant dry distillation liquid, roasted coffee beans, or tea leaves as raw materials for supplying reducing organic matter, it becomes possible to produce photocatalysts at even lower cost, and economically advantageous effects can be expected.

[0028] (a) Fruit juice As a raw material for supplying reducing organic matter, it is preferable to use "fruit juice." As the type of fruit used for fruit juice, the above-mentioned fruits can be preferably used. In particular, fruits with a high total polyphenol content are preferable in terms of potency. Furthermore, in consideration of raw material costs, it is preferable to use juice from grapes, bananas, apples, persimmons, tomatoes, citrus fruits, etc.

[0029] (b) Stem and leaf juice As a raw material for supplying reducing organic matter, it is preferable to use "squeezed juice of stems and leaves." As the type of plant used for the juice of stems and leaves, the above-mentioned plant stems and leaves can be preferably used. In particular, plants with a high total amount of polyphenols are preferable in terms of potency. Furthermore, in consideration of raw material costs, it is preferable to use the juice of horsetail, cypress, pine, cedar, etc.

[0030] (c) Plant carbonization liquid As a source of the reducing organic matter, it is preferable to use "plant dry distillation liquid." This source is presumed to contain a large amount of polyphenols as well as many reducing organic molecules such as phenols, organic acids, carbonyls, alcohols, amines, basic components, and other neutral components.

[0031] Here, the term "plant dry distillate" refers to a dry distillate (a viscous brown liquid) obtained by thermally decomposing a plant body in a reduced state. Its appearance is reddish brown to dark brown. It can be used as is, but it can also be used as a concentrated liquid, diluted liquid, or dried form of these. Specific examples of plant dry distillate include wood vinegar, bamboo vinegar, and rice husk vinegar. These are also suitable for use from the perspective of raw material costs.

[0032] (d) Roasted coffee beans As a raw material for supplying reducing organic matter, it is preferable to use a raw material derived from "roasted coffee beans." This raw material contains a very large amount of polyphenols. In this embodiment, the roasted coffee beans can be used as is or in a ground state. Alternatively, components extracted from the grounds with water or hot water (so-called brewed coffee components) can be used. Alternatively, the residue after extraction with water or hot water (so-called coffee grounds) can be used. In particular, from the perspective of raw material costs, it is most preferable to use "coffee grounds," which are discarded in large quantities after the extraction of coffee components.

[0033] Here, roasted coffee beans include any coffee beans roasted according to a conventional method. This also includes so-called ground (crushed) coffee beans. Ground coffee beans may also be roasted. The coffee beans used here can be any seeds of the coffee tree, Coffea arabica, C. canephora, or C. liberica. While green coffee beans may be used, those dried and stored as is commonly used are preferred. From the perspective of raw material costs, it is industrially preferable to use non-standard coffee beans. Roasting here can be any commonly used method, such as direct flame roasting, hot air roasting, far-infrared roasting, microwave roasting, heated steam roasting, and low-temperature roasting.

[0034] Furthermore, "pulverized" refers to the state in which ordinary coffee beans are ground using, for example, a coffee mill, grinder, millstone, etc., and includes a wide range of states from coarsely ground to powdered. Considering the efficiency of the reaction with iron, it is preferable to have a large surface area, so crushing, pulverization, powdering, etc. are preferred.

[0035] (d)Tea leaves As a raw material for supplying reducing organic matter, it is preferable to use a raw material derived from "tea leaves." This raw material contains a very large amount of polyphenols. In this embodiment, tea leaves can be used as they are or in a crushed state. Alternatively, components extracted from the crushed material with water or hot water (so-called brewed tea components) can be used. Alternatively, the residue after extraction with water or hot water (so-called used tea leaves) can be used. In particular, considering the cost of raw materials, it is most preferable to use "used tea leaves," which are discarded in large quantities after tea component extraction.

[0036] Here, any tea leaves can be used as long as they are picked from the stems and leaves of the tea plant, Camellia sinensis. Any picking method is acceptable, but from a cost perspective, mechanical picking is particularly preferred. Although oxidative fermentation occurs when the cellular contents of picked tea leaves mix, the present invention can use tea leaves at any stage of fermentation. For example, green tea (e.g., sencha, bancha, kukicha, and hojicha) that has been heated to suppress oxidative fermentation, partially fermented green tea (e.g., oolong tea), fully fermented black tea, and black tea (e.g., pu-erh tea) that has undergone further oxidative fermentation and koji mold fermentation can be used. Green tea, black tea, and oolong tea are preferred. From the perspective of raw material costs, it is industrially preferable to use non-standard tea leaves. Furthermore, considering the efficiency of the reaction with iron, it is preferable to use tea leaves with a large surface area, so crushing, pulverization, or other methods are preferred.

[0037] The above-mentioned raw materials for supplying reducing organic substances may be used alone or in combination of two or more.

[0038] Furthermore, a reducing gas can be used as a raw material for supplying carbon. Examples of the reducing gas include carbon monoxide (Co), hydrocarbon gas (hydrogen (H), methane (CH), propane (C), butane (C). 10) and the like. In addition, by using such a reducing gas, it becomes possible to produce a photocatalytic composition in an appropriate reducing atmosphere in the method for producing a photocatalytic composition described below.

[0039] [Iron supply raw materials] The photocatalytic composition of this embodiment contains at least one of a divalent iron supply material and a trivalent iron supply material as a raw material for supplying elemental iron. Alternatively, a metallic iron supply material may be used as the raw material for supplying elemental iron. A mixture of these materials may also be used.

[0040] Here, "divalent iron compounds (divalent iron supply materials)" include water-soluble iron compounds such as iron(II) chloride, iron(II) nitrate, iron(II) sulfate, iron(II) hydroxide, iron(II) oxide, iron(II) acetate, iron(II) lactate, sodium iron(II) citrate, and iron(II) gluconate; and insoluble divalent iron compounds such as iron(II) carbonate and iron(II) fumarate.

[0041] "Fe(III) feedstocks" include water-soluble ferric iron compounds such as ferric chloride, ferric sulfate, ferric citrate, ammonium ferric citrate, and ferric EDTA; and insoluble ferric iron compounds such as ferric oxide, ferric nitrate, ferric hydroxide, and ferric pyrophosphate.

[0042] Natural raw materials that contain large amounts of these trivalent iron compounds include soils such as Akadama soil, Kanuma soil, loam (soil containing a lot of allophanic iron), laterite (soil containing a lot of iron (III) oxide), and goethite (soil containing amorphous minerals); natural iron ores such as pyrite, marcasite, siderite, magnetite, and goethite; iron sand, which is formed when these iron ores are turned into dust; and biological substances such as heme iron and seashells.

[0043] Furthermore, examples of "raw materials for metallic iron" include iron materials such as smelted iron and alloys. Rust can also be used as a "raw material for metallic iron."

[0044] Furthermore, the "iron supply material" may be a reaction product obtained by mixing a reducing organic substance having iron-reducing ability or a feed material thereof with an iron supply material in the presence of water. More specifically, for example, the "iron supply material" may be a polyphenol-iron complex (divalent iron ion (Fe )) obtained by mixing a polyphenol or a feed material thereof with an iron supply material in the presence of water. 2+ ) forms a complex structure with a polyphenol.

[0045] Even if the iron supply source is water-insoluble, it can be directly used as the iron supply source because it is water-soluble due to the chelating ability of the reducing organic substance. Also, an aqueous solution containing the iron compound dissolved in water and containing ferrous ions and / or ferric ions can be used.

[0046] Among the above iron supply raw materials, in order to efficiently produce a photocatalytic composition, it is preferable to use a water-soluble divalent iron compound or trivalent iron compound. In particular, it is preferable to use inexpensive iron chloride, iron sulfate, etc. Furthermore, in order to produce the photocatalytic composition taking into consideration raw material costs and stable supply, it is preferable to use natural soil (particularly Akadama soil, Kanuma soil, loam, etc.) or metallic iron as the iron supply raw material.

[0047] [Glass material] The photocatalytic composition of this embodiment contains a raw material (silicon supply raw material) that supplies silicon as a glass material. Other known glass materials that are commonly used in the manufacture of glass and ceramics can also be used as the glass material. For example, materials that are commonly used in the manufacture of silicate glass (soda-lime glass, borosilicate glass, quartz glass, lead glass, etc.) can be used as the glass material.

[0048] "Silicon supply materials" include plants selected from grasses, ferns, and algae, as well as processed products of such plants. Grass plants include rice, castor oil, sugarcane, rush, bamboo, wheat, barley, corn, oats, turfgrass, sorghum, rye, foxtail millet, elephant grass, Japanese silver grass, and bamboo grass. Ferns include horsetail and field horsetail. Algae include diatoms (particularly chaetoceros).

[0049] Among these, rice and sugarcane are preferred, and rice husks, rice leaves, and sugarcane leaves, which are produced in large quantities as by-products in the agricultural industry, are most preferred. By using such by-products, photocatalysts can be produced at low cost, and economically advantageous effects can be expected.

[0050] Examples of "processed products" include dried products of the above-mentioned silicon-containing plants, squeezed juices, extracts, extracts, dried products of squeezed juices and extracts, etc. Dried products, squeezed juices, extracts, and extracts can be obtained by the same treatment as those for the above-mentioned reducing organic substances.

[0051] In addition to the above-mentioned plants or processed products, other "silicon supplying materials" that can be used include silicates, silicon, silicon dioxide (silica), silicon chloride, silica sand, glass (recycled glass), etc. It is also preferable to use a combination of these silicon supplying materials.

[0052] Examples of glass materials other than silicon supply raw materials include, but are not limited to, boron, boron oxide, sodium borate (particularly sodium tetraborate), soda ash, anhydrous sodium carbonate, limestone, calcium carbonate, potassium carbonate, etc. Furthermore, stabilizers, coloring materials for enhancing decorativeness, etc., can also be added to these glass materials.

[0053] A preferred mixing ratio of the above raw materials will now be described. The mixing ratio of the reducing organic substance and the iron supplying material should be such that the iron supplying material is contained in an amount equivalent to 0.1 parts by weight, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, even more preferably 2 parts by weight or more, particularly preferably 3 parts by weight or more, and even more preferably 4 parts by weight or more, of elemental iron per 100 parts by weight of the dry weight of the reducing organic substance or the source material of the reducing organic substance. If the proportion of elemental iron is too low (if the mixing ratio of the reducing organic substance relative to elemental iron is too high), the excess reducing organic substance will function as a radical scavenger (scavenger), which may inhibit photocatalytic activity.

[0054] The upper limit of the amount of iron element is 10 parts by weight or less, preferably 8 parts by weight or less, and more preferably 6 parts by weight or less, calculated as the weight of iron element. If the proportion of iron element is too high (if the mixing ratio of the reducing organic substance relative to iron element is too low), the iron ions cannot be maintained in a divalent state, and the photocatalytic activity decreases, which is undesirable.

[0055] On the other hand, the mixing ratio of the reducing organic substance and the silicon supplying material is such that the silicon supplying material is contained in an amount of 5 parts by weight or more, preferably 10 parts by weight or more, more preferably 50 parts by weight or more, even more preferably 60 parts by weight or more, and particularly preferably 90 parts by weight or more, per 100 parts by weight of the total of the reducing organic substance or the supplying material (dry weight) of the reducing organic substance and the iron supplying material. If the proportion of silicon element is too low (if the mixing ratio of the reducing organic substance relative to the silicon element is too high), glass ceramics will not be formed, which is not preferable.

[0056] The upper limit of the amount of elemental silicon is 99 parts by weight or less, preferably 60 parts by weight or less, and more preferably 30 parts by weight or less, calculated as the weight of elemental silicon. If the proportion of elemental silicon is too high (if the mixing ratio of the reducing organic substance relative to elemental silicon is too low), glass ceramics cannot be formed, which is not preferable. The silicon supply material (dry weight) is preferably blended in an amount of 100 parts by weight or more, more preferably 200 parts by weight or more, and even more preferably about 300 parts by weight, per 100 parts by weight of the total of the reducing organic substance or the reducing organic substance supply material (dry weight) and the iron supply material.

[0057] When a plant extract or extract is used as the reducing organic matter supplying material or silicon supplying material, the dry weight of the plant used as the extraction material can be regarded as the "dry weight of the reducing organic matter supplying material" and the mixing ratio can be calculated. For example, suppose dried tea leaves are used as the reducing organic matter supplying material, and the extract obtained by extracting the tea leaves with hot water is reacted with the iron supplying material. In this case, the weight of the dried tea leaves is used as the "dry weight of the reducing organic matter supplying material" to calculate the mixing ratio with the iron supplying material.

[0058] As mentioned above, the inventors have developed a photocatalyst by mixing a reducing organic substance and an iron source material in the presence of water, followed by the resulting reaction product. More specifically, a polyphenol-iron complex obtained by mixing polyphenols and an iron source material in the presence of water. While this polyphenol-iron complex exhibits photocatalytic activity under visible light, its stability (sustainability) remains an issue. To address this issue, the inventors hypothesized that carbon in the polyphenol-iron complex receives electrons from light and transfers them to the iron, thereby stabilizing the iron in its current state. Therefore, they hypothesized that a stable photocatalyst could be obtained by combining carbon with the iron to enhance the stability of the polyphenol-iron complex. However, combining the iron and carbon proved difficult. After investigating various reaction conditions, they produced glass using polyphenols and an iron source, and successfully combined the iron and carbon. Furthermore, they discovered that the silicon contained in the glass material enhances the photocatalytic stability. The following describes a method for producing a photocatalyst composition according to this embodiment.

[0059] (Method of producing photocatalytic composition) The method for producing a photocatalytic composition according to this embodiment includes a step (heating step) of heat-treating a mixture of a reducing organic substance capable of reducing iron(III) to iron(II), an iron supply raw material, and a glass material in a reducing atmosphere at a heating temperature of 900°C or higher for a heating time of 12 minutes or longer. By producing a photocatalytic composition through this heating step (more specifically, a reduction firing step), the raw materials can be appropriately melted to improve the quality of the glass, and the bonding strength between carbon and iron(II) can be increased, resulting in a photocatalytic composition with stable photocatalytic activity.

[0060] The heating temperature should be 900°C or higher, and more preferably 1200°C or higher and 1300°C or lower. The heating time should be 12 minutes or higher, more preferably 12 minutes to 12 hours, and even more preferably 12 minutes to 3 hours. Taking into consideration the melting state and work efficiency, the heating temperature should be about 20 minutes (0.33 hours). By performing the heating step at such a temperature and time, the raw materials are more appropriately melted and crystallization is promoted, resulting in a photocatalytic composition with superior glass quality, stronger bonding between carbon and divalent iron, and more stable photocatalytic activity.

[0061] Furthermore, by carrying out the heating step in a reducing atmosphere, the action of reducing the trivalent iron in the reducing organic matter to divalent iron can be enhanced. Note that, by heating, the reducing organic matter is carbonized and carbon dioxide is generated, making it possible to carry out the heating step in a reducing atmosphere, but by supplying a reducing gas as described above in the heating step, the reduction action can be made more appropriate.

[0062] In addition to the heating step, the method also includes a mixing step, a cooling step, a grinding step, and the like. The mixing step involves adding a glass material containing a reducing organic substance, an iron source material, and a silicon source material in a predetermined mixing ratio into a container such as a crucible and mixing them. The cooling step involves appropriately cooling and vitrifying the molten material obtained in the heating step. This cooling step vitrifies the molten material, producing a photocatalytic composition composed of glass or glass ceramics. This cooling step produces glass or glass ceramics in the form of a plate or block (hereinafter referred to as "plate glass" or "glass block"). This plate glass or glass block can be used as a photocatalytic composition directly, or can be divided into appropriate sizes to produce a photocatalytic composition. In such photocatalytic compositions, photocatalytically active carbon-iron complexes (reaction products) are dispersed within and on the surface, and photocatalytic reactions occur due to the reaction products on the surface of the photocatalytic composition. Even if the surface of the photocatalytic composition is scraped, photocatalytic reactions occur due to the reaction products present on the newly exposed surface, thereby maintaining excellent photocatalytic activity.

[0063] Alternatively, plate glass or glass lumps can be pulverized by a pulverization process, and the resulting pulverized material can be used as a photocatalytic composition. In this pulverization process, plate glass or glass lumps are pulverized manually using a hammer or mortar, or using a device such as a pulverizer or bead mill, to obtain a pulverized material. Examples of the pulverized material include beads, granules, and powder. In the photocatalytic composition pulverized in this manner, the increased surface area increases the contact with the organic matter to be decomposed or the microorganisms to be sterilized, thereby further improving the photocatalytic activity.

[0064] Fig. 1 is a flowchart showing a preferred example of the manufacturing process of the photocatalytic composition of this embodiment. As shown in Fig. 1, the manufacturing process of the photocatalytic composition of this embodiment includes a mixing step, a heating step, a cooling step, and a crushing step, but may also include other steps necessary for glass manufacturing.

[0065] The photocatalytic composition of this embodiment may be in the form of any one of plate glass, glass lump, or crushed material in the form of beads, granules, or powder, and can be in an appropriate form depending on the application and form of use. In addition, photocatalytic compositions in multiple forms can be used in combination.

[0066] The shape of the photocatalytic composition of this embodiment is preferably rectangular in the case of plate glass, but examples include triangles, polygons with pentagons or more, circles, and ovals. Examples also include shapes that enhance decorativeness and aesthetic appeal, such as stars and hearts. In this case, the size (outer diameter) is preferably 1 mm or more and 50 mm or less. In the case of glass chunks or crushed material, examples include spheres, spheroids, cylinders, prisms, cones, and pyramids, but irregular shapes are also acceptable. In this case, the size is preferably 1 mm or more and 50 mm or less. In the case of powder, the shape is not particularly limited, and the size (particle size) is preferably an average particle diameter of 0.1 μm or more and 5 mm or less. Here, "average particle size" refers to the particle size at 50% of the integrated value in the particle size distribution determined by laser diffraction / scattering.

[0067] The photocatalytic composition of this embodiment produced by the above-mentioned production method has excellent photocatalytic activity and excellent stability that allows this excellent photocatalytic activity to be maintained for a long period of time. In this photocatalytic composition, carbon derived from reducing organic matter converts iron ions into a divalent state (Fe 2+ It is also speculated that the silicon in the silicon supply source increases the bonding strength between carbon and iron, increasing the stability of the photocatalyst.

[0068] The photocatalytic composition of this embodiment has the property of absorbing sunlight and light in a wide wavelength range of 200 to 1400 nm, i.e., not only ultraviolet light but also visible light and infrared light, and exhibits excellent photocatalytic activity when irradiated with the composition.

[0069] Here, "ultraviolet light" refers to light with a wavelength range of 380 nm or less. "Visible light" refers to light with a wavelength of 380 to 750 nm, which is the wavelength range visible to the human eye. Specifically, "visible light" includes light with wavelength ranges of 380 nm to 450 nm (purple light), 450 nm to 495 nm (blue light), 495 nm to 570 nm (green light), 570 nm to 590 nm (yellow light), 590 nm to 620 nm (orange light), and 620 nm to 750 nm (red light). "Infrared light" refers to light with a wavelength range of 750 nm or more.

[0070] In particular, this photocatalytic composition exhibits extremely strong photocatalytic activity (sterilizing action) when irradiated with ultraviolet light, and its activity is particularly strong in the near-ultraviolet wavelength range of 200 nm to 380 nm, demonstrating far greater photocatalytic activity than titanium oxide.

[0071] Furthermore, the photocatalytic composition of this embodiment exhibits strong photocatalytic activity even when irradiated with visible light and infrared light, wavelength ranges where titanium oxide does not exhibit activity. This photocatalytic composition exhibits strong activity in the visible light wavelength range, particularly in the short wavelength range of violet to blue light (380 to 495 nm). This photocatalytic composition exhibits strong activity in the infrared wavelength range of near infrared light, 750 to 1400 nm (particularly around 900 to 1300 nm, and more particularly around 1100 to 1300 nm).

[0072] Examples of light to be irradiated onto the photocatalytic composition of this embodiment include natural light (sunlight) containing visible light, ultraviolet light, infrared light, and the like, and illumination light irradiating light of a predetermined wavelength. For example, under sunlight, the photocatalytic activity of the photocatalytic composition is objectively detected, enabling decomposition of organic matter and sterilization within a few seconds. Furthermore, white LED light from a white LED light source is preferred as illumination light, which is suitable for indoor use. Using the photocatalytic composition in an environment with weak natural light, such as indoors, can enhance the photocatalytic activity of the photocatalytic composition and further enhance its organic matter decomposition and sterilization effects.

[0073] The photocatalytic composition of this embodiment absorbs irradiated light energy and exhibits activity to decompose nearby organic substances, etc. It is presumed that this activity is a phenomenon exerted by radicals generated by the photocatalyst excited by light energy.

[0074] The photocatalytic composition of this embodiment has the property of continuously exhibiting photocatalytic activity during continuous irradiation with light. Furthermore, even if light irradiation is interrupted once, this photocatalytic composition exhibits photocatalytic activity upon re-irradiation. In other words, this photocatalytic composition is a material that can be used repeatedly as a photocatalyst. This is because the reaction product (Fe 2+ The resonance structure in the molecule of the complex transfers light energy to the Fe 2+ It is speculated that this is because the silicon in the silicon supply source enhances the bonding between carbon and iron, resulting in increased stability as a photocatalyst.

[0075] The photocatalytic composition of this embodiment does not use titanium or other elements, and its impact on the human body and the environment is suppressed. Therefore, it can be used in a variety of applications, including medicine, food, public health, agriculture, and industry. Specifically, ascorbic acid and polyphenols are used as reducing organic substances, which are derived from food-derived feedstocks, and therefore, applications in the food industry are particularly anticipated. Ascorbic acid is particularly suitable because it is colorless and transparent. Furthermore, when plant dry distillate is used as the reducing organic substance feedstock, the components contain substances with a slight odor. However, because the feedstock is very inexpensive, applications in fields such as agriculture, medicine, and public health are anticipated.

[0076] Furthermore, in the photocatalytic composition of this embodiment, the glass material contains a silicon supply source consisting of a plant selected from grasses, ferns, and algae, or a processed product of the plant. This also indicates that the photocatalytic composition of this embodiment can be used in a variety of applications, including medicine, food, public health, agriculture, and industry, and can provide a stable photocatalytic composition by enhancing the bonding strength between carbon and divalent iron through silicon. Furthermore, the use of grasses, ferns, algae, and other sources rich in silicic acid as silicon supply sources is expected to lead to research exploring these new possibilities. Furthermore, utilizing plant resources can reduce impacts on the human body and the environment, provide inexpensive raw materials, reduce waste, and provide a photocatalytic composition with high added value.

[0077] The photocatalytic composition of this embodiment exhibits activity not only when irradiated with ultraviolet light but also when irradiated with visible light or infrared light. This makes it possible for the photocatalytic composition of this embodiment to be used in a variety of applications that were previously difficult to achieve with titanium oxides of the prior art. For example, the composition can be used in ordinary indoor spaces or in liquids placed indoors (such as water in containers like vases or aquariums).

[0078] (organic matter decomposer, disinfectant, deodorizer) The photocatalytic composition of this embodiment has excellent photocatalytic activity and excellent stability, and therefore can be suitably used as an organic matter decomposer, a disinfectant, and a deodorizer. Each of these will be described below.

[0079] (organic matter decomposer) The organic matter decomposing agent of the present embodiment contains the above-described photocatalytic composition that exhibits catalytic activity under visible light. Therefore, the organic matter decomposing agent of the present embodiment has excellent photocatalytic activity for light of a wide range of wavelengths, including visible light, and is also highly stable, making it suitable for use in the decomposition of various organic substances. In particular, this photocatalytic composition can be suitably used for the decomposition of organic pollutants and harmful substances, making it useful in a process of environmental purification.

[0080] Here, pollutants and harmful substances refer to substances that cause water pollution, soil pollution, and air pollution, such as organic substances that affect the human body and the environment and are contained in domestic wastewater, human wastewater, industrial wastewater, polluted river and lake water, soil from garbage dumps, industrial waste, farmland, and former factory sites.

[0081] Specific organic substances to be decomposed include, for example, detergents, food and drink residues, human waste, feces, pesticides, odorous substances, waste oil, dioxins, PCBs, DNA, RNA, proteins, and other organic wastes.

[0082] The organic matter decomposing agent of the present embodiment has an extremely strong decomposition effect, and can efficiently decompose difficult-to-decompose organic matter (e.g., basic fuchsin). For example, when irradiated with light of 100 W / m², it is possible to decompose at least 2.5 mg / L of organic matter per day, and in some cases, 35 mg / L or more.

[0083] (fungicide) The disinfectant of this embodiment contains a photocatalytic composition that exhibits catalytic activity under visible light. Therefore, the disinfectant of this embodiment has excellent photocatalytic activity over a wide range of wavelengths, including visible light, and is also highly stable, making it suitable for use in sterilizing a variety of objects. Specific examples of objects that can be sterilized include medical instruments, hospital room walls, patient affected areas, clothing, bedding, food manufacturing equipment lines, food ingredients, kitchen utensils such as cutting boards and knives, tableware, toilet seats, handrails, agricultural equipment, and hydroponic cultivation equipment and nutrient solutions. Unlike conventional sterilization methods using titanium dioxide, the disinfectant of this embodiment can be irradiated with visible light or infrared light, significantly improving its applications and scenarios. Furthermore, the disinfectant of this embodiment can sterilize not only bacteria, but also eukaryotic microorganisms, algae, archaea, viruses, viroids, and the like.

[0084] The disinfectant of this embodiment has an extremely strong disinfecting effect, so that in the case of surface disinfection, for example, a sufficient disinfecting effect can be obtained by irradiation with sunlight for a few minutes, preferably 10 minutes or more, more preferably 20 minutes or more. Even when irradiating relatively weak light such as LED or fluorescent light, a sufficient disinfecting effect can be obtained by treatment for 1 hour or more, preferably 6 hours or more, more preferably 12 hours or more.

[0085] (Deodorant) The deodorant of the present embodiment contains the photocatalytic composition that exhibits catalytic activity when exposed to visible light. As described above, the photocatalytic composition of the present embodiment has excellent organic matter decomposition and sterilization effects, and can therefore suppress the generation of organic odors and odors caused by the decomposition of organic matter by microorganisms.

[0086] Therefore, the deodorizer of the present embodiment can be used to deodorize various odors. In particular, it can exhibit an excellent deodorizing effect on odors generated by organic matter, such as those described above in the description of the organic matter decomposer. Furthermore, it can effectively suppress the generation of odors caused by the decomposition of organic matter by microorganisms, such as those described above in the description of the disinfectant.

[0087] As described above, when the photocatalytic composition of the present embodiment is used as an organic matter decomposer, bactericide, or deodorizer, its form may be, for example, plate glass or glass block, or may further be pulverized in the form of beads, granules, or powder. Such organic matter decomposers, bactericides, or deodorizers can be placed directly or in a container or the like, placed in the gas or liquid to be decomposed, sterilized, or deodorized, and irradiated with light, thereby exhibiting organic matter decomposition, bactericidal, and deodorizing effects. The photocatalytic composition can also be used as a coating agent containing the photocatalytic composition in the form of a pulverized bead, granule, or powder. (Use in hydrogen production methods) The photocatalytic composition of this embodiment has excellent photocatalytic activity and excellent stability, and therefore can be suitably used in a hydrogen production method. The strong photocatalytic activity of the photocatalytic composition allows for the oxidative decomposition of water into oxygen and hydrogen. That is, according to the present disclosure, a hydrogen production method is provided, which includes a step of generating hydrogen by oxidative decomposition of water using the photocatalytic composition. When the photocatalytic composition of this embodiment is used in a hydrogen production method, its form may be, for example, plate glass or glass chunks, or may be crushed into beads, granules, or powder. The photocatalytic composition in such a form can be placed in water as is or in a container, and irradiated with light to generate hydrogen. [Example]

[0088] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to the following examples.

[0089] Example 1 Example of production of photocatalytic composition of Example 1 [Raw materials] [Table 1]

[0090] [Manufacturing process] The raw materials listed in Table 1 above were placed in a crucible and heated to 1200-1300°C under a reducing atmosphere using a high-pressure burner until the raw materials were melted, producing a photocatalytic composition consisting of plate glass. The heating time was approximately 20 minutes. Used tea leaves (residue from hot water extraction of tea leaves) were used as the tea leaves (reducible organic matter supplying raw material), and iron (III) chloride (FeCl3), a trivalent iron compound, was used as the iron salt (iron supplying raw material). The mixing ratio of tea leaves and iron salt was 4 parts by weight of iron salt in elemental iron equivalent to 100 parts by weight of tea leaves (dry weight equivalent). Rice husks were used as the silicon supplying raw material. The mixing ratio of tea leaves + iron and rice husks was 100 parts by weight of rice husks (30 parts by weight or more in elemental silicon equivalent) to 100 parts by weight of tea leaves + iron salt (dry weight equivalent).

[0091] The melt obtained by the above process was allowed to cool to produce a plate-shaped photocatalytic composition (plate glass). Next, the photocatalytic composition made of this plate glass was pulverized to produce a powdered photocatalytic composition (powdered glass) of Example 1. Figure 2(a) shows a photograph of the photocatalytic composition (plate glass) before pulverization, and Figure 2(b) shows a photograph of the photocatalytic composition (powdered glass) of Example 1 after pulverization.

[0092] Example 2 Glass beads were prepared using the raw material mixing ratio and production method as described in Example 1 above, and used as the bead-shaped photocatalytic composition of Example 2.

[0093] When rice husks are used as the silicon supply raw material, the mixing ratio of the raw materials (amount of each raw material) of the photocatalytic composition may be within the range shown in Table 2 below, but it is most preferable to use the mixing ratios shown in Examples 1 and 2 above, which will allow for the production of a photocatalytic composition with excellent glass quality and photocatalytic activity. [Table 2]

[0094] Example 3 The photocatalytic composition of Example 3 was produced using sugarcane leaf ash as a silicon supply material. The raw materials are shown in Table 3 below. The production process of the photocatalytic composition of Example 3 was the same as the production process of Example 1. [Raw materials] [Table 3]

[0095] Example 4 The photocatalytic composition of Example 4 was produced using ascorbic acid as a reducing organic material supplying material. The raw materials are shown in Table 4 below. The ascorbic acid and iron salt were mixed in a 1:1 ratio (1 g of ascorbic acid + 1 g of iron salt). The production process of the photocatalytic composition of Example 4 was the same as the production process of Example 1. [Raw materials] [Table 4]

[0096] Using the powdered photocatalyst composition of Example 1 and the beaded photocatalyst composition of Example 2, various performance verification experiments and component analyses were carried out as shown below. The light spectrum distribution of the white LED light source used in each experiment is shown in Figure 3. Figure 3 shows that the white LED light contains visible light in the range of 380 to 750 nm.

[0097] [Analysis of component composition] The component composition of the photocatalyst composition of Example 1 was analyzed using the analytical methods shown in Table 5 below. Similarly, component analysis was performed on the photocatalysts of Reference Examples 1 and 2. The analysis results are shown in Table 5 below. The values ​​in Table 5 below indicate the content (wt%) of each component in the photocatalyst composition or polyphenol-iron complex.

[0098] As the photocatalyst for Reference Example 1, an aqueous solution containing used tea leaves and iron (III) chloride (mixing ratio the same as in Example 1) was prepared and left to stand at room temperature for several minutes to obtain a polyphenol-iron complex derived from used tea leaves. As the photocatalyst for Reference Example 2, an aqueous solution containing coffee grounds and iron (III) chloride (mixing ratio the same as in Example 1) was prepared and left to stand at room temperature for several minutes to obtain a polyphenol-iron complex derived from coffee grounds.

[0099] [Table 5] Analysis method: ICP emission spectroscopy, dipyridyl reaction analysis, oxygen circulation combustion method, X-ray photoelectron spectroscopy (XPS: X-ray Photoelectron Spectroscopy or ESCA: Electron Spectroscopy for Chemical Analysis)

[0100] [Experimental Example 1: Verification experiment of iron reduction ability] A verification experiment of the iron reduction ability was carried out by dipyridyl reaction analysis for the powdered photocatalytic composition of Example 1. Specifically, dipyridyl and acetic acid were added to and mixed with the photocatalytic composition so that the dipyridyl concentration was 2 g / L and the acetic acid concentration was 100 g / L, and the presence or absence of a color reaction was examined.

[0101] Here, dipyridyl is a substance that does not react with trivalent iron and remains colorless, but turns red when it reacts with divalent iron. It is used to detect divalent iron. As a result, the solution containing the powdered photocatalyst composition of Example 1 turned red. This indicates that the trivalent iron added as a raw material for the photocatalyst composition was reduced to divalent iron by heating in a reducing atmosphere (reductive calcination). Furthermore, it was shown that the reduced divalent iron is stably maintained in the divalent iron state. Figure 2(c) shows a photograph of the powdered photocatalyst composition of Example 1 stained with dipyridyl and turning red.

[0102] [Experimental Example 2: Decomposition effect of harmful substances by photocatalytic composition under white LED light irradiation] In order to verify the effect of the photocatalytic reaction of the photocatalytic composition of Example 1 in decomposing harmful substances, a methylene blue decomposition experiment was carried out using white LED light, which is visible light. Experimental Method: 10 mg of the powdered photocatalytic composition of Example 1 was added to 10 ml of methylene blue solution (5000 ppm methylene blue solution diluted 1000 times with water to 5 ppm), and the mixture was continuously irradiated with white LED light (30,000 lux) to measure the decomposition rate of methylene blue. 10 μL of methylene blue solution was added at regular intervals to repeatedly decompose the methylene blue. A similar experiment was also conducted using titanium oxide as a control.

[0103] Experimental results: The experimental results are shown in a graph in Figure 4(a). The arrows in the graph in Figure 4(a) indicate the addition of 10 μL of methylene blue solution. Figure 4(b) shows a photograph of the solution in the control group after the experiment, and Figure 4(c) shows a photograph of the solution in the light-irradiated group of the photocatalytic composition of Example 1 after the experiment.

[0104] As shown in Figure 4(a), in the control area using titanium dioxide, methylene blue did not decompose, and the concentration increased with the addition of methylene blue. Also, as shown in the photograph in Figure 4(b), the solution in the control area remained the color of methylene blue (blue). This is because titanium dioxide does not undergo a photocatalytic reaction under white LED light (visible light).

[0105] In contrast, in the light irradiation section using the photocatalyst composition of Example 1, even when methylene blue was added, methylene blue was decomposed and its concentration decreased by continuous irradiation with a white LED, as shown in Figure 4(a). Furthermore, as shown in the photographic image in Figure 4(c), in the light irradiation section using the photocatalyst composition, the color of the solution became transparent, indicating that the methylene blue had been decomposed. Therefore, it was found that the photocatalyst composition of Example 1 exhibited a strong photocatalytic reaction to white LED light (visible light) and was excellent in decomposing harmful substances such as methylene blue.

[0106] [Experimental Example 3: Decomposition effect of harmful substances by photocatalytic composition under ultraviolet irradiation] In order to verify the decomposition effect of harmful substances by the photocatalytic reaction of the photocatalytic composition of Example 1, a methylene blue decomposition experiment was carried out using ultraviolet light. Experimental Method: A methylene blue decomposition experiment was conducted in the same manner as in Experimental Example 2 above, using an ultraviolet LED light source (see Figure 5) as the light source (ultraviolet irradiation area). Similar experiments were also conducted in a control area without photocatalyst addition and a titanium oxide area using titanium oxide. For the experiment, the concentrations of iron and titanium oxide in the photocatalyst composition were adjusted to be the same, and each was added to a methylene blue solution. Next, ultraviolet light was irradiated continuously for 24 hours, and the decomposition of methylene blue was observed.

[0107] Experimental results: FIG. 5 shows photographs of the experimental results. In FIG. 5, (a) is a photograph of the solution in the control group (without photocatalyst), (b) is a photograph of the solution in the UV-irradiated group using the photocatalyst composition of Example 1, and (c) is a photograph of the solution in the titanium oxide group using titanium oxide. As shown in these figures, in the control group (a), the solution remained blue and methylene blue was not decomposed. In contrast, in the UV-irradiated group using the photocatalyst composition of Example 1 (b) and the titanium oxide group (c), decomposition of methylene blue was observed. Therefore, it was found that the photocatalyst composition of Example 1 exhibited a strong photocatalytic reaction to UV rays and was excellent in decomposing harmful substances such as methylene blue.

[0108] [Experimental Example 4: Decomposition effect of harmful substances by photocatalytic composition irradiated with near-infrared rays] In order to verify the decomposition effect of harmful substances by the photocatalytic reaction of the photocatalytic composition of Example 1, a methylene blue decomposition experiment was carried out using near-infrared rays. Experimental Method: A methylene blue decomposition experiment was conducted in the same manner as in Experimental Examples 2 and 3 above, using a near-infrared LED light source (near-infrared irradiation group). Similar experiments were also conducted for a control group without photocatalyst addition and for titanium oxide containing titanium oxide. For the experiment, the concentrations of iron and titanium oxide in the photocatalyst composition were adjusted to be the same, and each was added to a methylene blue solution. Next, near-infrared light (1200 nm) was irradiated continuously for 5 days, and the decomposition of methylene blue was observed.

[0109] Experimental results: FIG. 6 shows photographs of the experimental results. In FIG. 6, (a) is a photograph of the solution in the control group, (b) is a photograph of the solution in the control group using titanium oxide, and (c) is a photograph of the solution in the near-infrared irradiated group using the photocatalyst composition of Example 1. As shown in FIG. 6, in the control group (a) and the titanium oxide group (b), the solution remained blue and methylene blue was not decomposed. In contrast, in the near-infrared irradiated group using the photocatalyst composition of Example 1 (c), decomposition of methylene blue was observed. Therefore, it was found that the photocatalyst composition of Example 1 exhibited a strong photocatalytic reaction to near-infrared rays and was excellent in decomposing harmful substances such as methylene blue.

[0110] From the experimental results of Experimental Examples 2 to 4, it was confirmed that the photocatalytic composition of Example 1 exhibits excellent photocatalytic activity over a wide wavelength range, including ultraviolet light, visible light, and infrared light. In contrast, it was confirmed that when titanium oxide was used, photocatalytic activity was not exhibited over visible light or near-infrared light. Furthermore, similar experiments were conducted on the photocatalytic compositions of Examples 3 and 4, and it was confirmed that they exhibit excellent photocatalytic activity over a wide wavelength range, including ultraviolet light, visible light, and infrared light.

[0111] [Experimental Example 5: Sterilization effect of microorganisms] A pathogenic bacteria sterilization experiment was conducted to verify the sterilization effect of the photocatalytic reaction of the photocatalytic composition of Example 1. Escherichia coli 0-157, which causes contamination of cut vegetables, and Ralstonia olanacearum, a plant pathogen, were used as test microorganisms (pathogenic bacteria).

[0112] Experimental Method: 10 mg of the powdered photocatalytic composition of Example 1 and 900 μL of bacterial suspension of each pathogen were placed in an Eppendorf tube and continuously irradiated with white LED (30,000 lux) for 30 minutes (light irradiation group). As controls, a "light irradiation only group" was prepared in which no photocatalytic composition was added and only white LED light irradiation was performed, and a "dark condition group" was prepared in which the photocatalytic composition was added but no white LED light irradiation was performed and the group was left in the dark. In addition, the viability of each pathogen in each treatment group was determined using flow cytometry.

[0113] Experimental results: Figure 7 shows photographs of each treatment group after treatment with E. coli. Figure 7(a) shows the control group (treated with light irradiation only), Figure 7(b) shows the control group (dark condition group) using the photocatalytic composition, and Figure 7(c) shows the control group (light irradiation group) using the photocatalytic composition.

[0114] Figure 8 shows the results of determining whether E. coli is viable or dead by flow cytometry. Figure 8(a) shows the results of determining whether E. coli is viable or dead in the "dark condition group" where a photocatalytic composition was used as a control group, and Figure 8(b) shows the results of determining whether E. coli is viable or dead in the "light irradiation group" where a photocatalytic composition was used. Figure 9 shows the results of determining whether R. solanacearum is viable or dead by flow cytometry. Figure 9(a) shows the results of determining whether R. solanacearum is viable or dead in the "dark condition group" where a photocatalytic composition was used as a control group, and Figure 9(b) shows the results of determining whether R. solanacearum is viable or dead in the "light irradiation group" where a photocatalytic composition was used.

[0115] As can be seen from Figures 8 and 9, survival of E. coli was confirmed in the "light irradiation only treatment group" and the "dark condition group," whereas complete annihilation of E. coli was confirmed in the "light irradiation group" where irradiation with white LED light was performed using the photocatalytic composition of Example 1. Furthermore, as can be seen from Figure 9, a high bactericidal effect against bacterial wilt disease bacteria was confirmed in the "light irradiation group" where irradiation with white LED light was performed using the photocatalytic composition of Example 1.

[0116] [Experimental Example 6: Experiment to identify radical species by luminol reaction of photocatalytic composition] For the photocatalytic composition of Example 1, an experiment to identify radical species (detection of ·O2 and H2O2) was carried out by a luminescence method using luminol. Experimental method The reaction of luminol with ·O2 produces 425 nm luminescence, which is detected by photon counting. This method can reveal the presence of ·O2.

[0117] Experimental results The results of the identification experiment are shown in Figure 10. As shown in Figure 10, a high luminol reaction was observed in the photocatalytic composition of Example 1. Since luminol has the property of reacting with hydrogen peroxide in addition to O2, it was revealed that hydrogen peroxide was generated during the reaction. It was also revealed that adding a radical scavenger to this reaction solution reduced the number of photons.

[0118] Experimental Example 7: Superoxide radical (·O2) using MPEC reagent - ) Identification experiment] For the photocatalytic composition of Example 1, the superoxide radical (·O2 - ) identification experiments were conducted. Experimental method The MPEC reagent contains superoxide (·O2 - ) specifically reacts with MPEC. - ) and the amount of light produced by the reaction with superoxide (·O2 - ) was confirmed to be present.

[0119] Experimental results The results of the identification experiment are shown in Figure 11. As shown in Figure 11, when the photocatalytic composition of Example 1 was irradiated with white LED light, superoxide (·O2 - It was found that the number of photons was reduced by adding a superoxide radical scavenger to this reaction solution.

[0120] [Experimental Example 8: Identification of hydroxyl radicals by ESR method using spin traps] For the photocatalytic composition of Example 1, an experiment for identifying hydroxyl radicals was carried out by ESR method using a spin trap. Experimental Method: 960 μL of distilled water was placed in an Eppendorf tube, and 20 mg of the photocatalyst composition of Example 1 was added. 40 μL of 180 mM spin trapping agent DMPO was then added, and ESR spectra were measured using an ESR (Electron Spin Resonance) device after irradiation with ultraviolet LED light (UV light) for 30 seconds, 60 seconds, and 30 minutes. Furthermore, the reaction of the photocatalyst composition with white LED light (visible light) was analyzed by ESR.

[0121] Experimental results: Figure 12 shows the results of an experiment to identify hydroxyl radicals using the ESR method with spin traps, showing the results of ESR spectrum measurements following irradiation with UV LED light. Figure 13 shows the results of ESR analysis following irradiation with white LED light (visible light). The "Reference" in Figure 13 is the ESR analysis result when no photocatalytic composition was added. As shown in Figure 12, no radicals were generated following UV irradiation for 30 and 60 seconds. In contrast, the generation of hydroxyl radicals (·OH) was observed following UV irradiation for 30 minutes. Furthermore, as shown in Figure 13, ESR analysis of the reaction between the photocatalytic composition and visible light confirmed the detection of hydroxyl radicals (·OH).

[0122] Furthermore, ESR analysis revealed that in addition to hydroxyl radicals, methyl radicals (·CH3) and carbon-based radicals were also generated by the reaction with ultraviolet LED light (UV light). Table 6 below shows whether or not radicals were generated in the photocatalytic composition, polyphenol-iron complex, and titanium oxide. As controls, similar experiments were also conducted using the polyphenol-iron complex derived from used tea leaves in Reference Example 1 and titanium oxide as a conventional example. In Table 6, ◯ indicates that radicals were generated, ◎ indicates that a large number of radicals were generated, and × indicates that no radicals were generated.

[0123] [Table 6]

[0124] [Experimental Example 9: Freshness preservation effect of cut flowers (camellia)] An experiment was carried out to verify the effect of the photocatalytic composition of Example 2 in maintaining the freshness of cut flowers. Test flower: Camellia Experimental Method: 100 ml of distilled water and 4 g of the bead-shaped photocatalytic composition of Example 2 were placed in a 200 ml beaker, and camellia flowers were floated on top. White LED light was continuously irradiated onto the bead-shaped flowers (see the photograph in Figure 14(a)), and the condition was observed after 10 days. The white LED light was irradiated between 8:00 and 18:00, and was turned off between 18:00 and 8:00 the following morning. A dark condition area with no light irradiation was used as a control.

[0125] Experimental results: Figure 14 shows photographs of the light irradiation area and the control area 10 days after the start of the experiment. In Figure 14, (b) is a photograph of the light irradiation area after 10 days, and (c) is a photograph of the control area after 10 days. As shown in Figure 14(c), in the control area (dark condition area), camellia flowers rotted and the distilled water turned yellow. In contrast, as shown in Figure 14(b), in the light irradiation area where white LED light was used with the photocatalytic composition of Example 2, no rot was observed in the camellia flowers and the distilled water remained clear. This confirmed that the photocatalytic composition of Example 2 can be used to maintain the freshness of cut flowers.

[0126] [Experimental Example 8: Freshness preservation effect of cut flowers (Saponaria vaccaria)] Experiments were conducted to verify the freshness-preserving effect of the photocatalytic composition of Example 2 on other different cut flowers. Test flower: Saponaria vaccaria Experimental Method: 50 ml of distilled water and 4 g of the bead-shaped photocatalytic composition of Example 2 were placed in a 100 ml plant box, and cut Saponaria vaccaria flowers were placed in the vase as test flowers. White LED light was continuously irradiated onto the vase, and the condition was observed after three days. The white LED light was irradiated between 8:00 and 18:00, and was turned off between 18:00 and 8:00 the following morning. A dark condition plot with no light irradiation was used as a control plot.

[0127] Experimental results: Figure 15(a) shows photographs of the white LED light irradiation area and the control area at the start of the experiment. Figure 15(b) shows photographs of the white LED light irradiation area and the control area three days after the start of the experiment. As shown in these photographs, the distilled water in the control area (dark condition area) became cloudy and white due to the growth of microorganisms three days after the start of the test. In contrast, in the area irradiated with white LED light using the photocatalytic composition of Example 2, no spoilage of the distilled water was observed even three days after the start of the test, and the distilled water remained clear. These experimental results also confirmed that the photocatalytic composition of Example 2 can be used to maintain the freshness of cut flowers.

[0128] [Experimental Example 9: Sterilization effect of seeds by ultraviolet irradiation of photocatalytic composition] An experiment was carried out to verify the sterilization effect of the photocatalytic composition of Example 2 on seeds by irradiating it with ultraviolet light. Test seeds: chickpeas Experimental Method: 4 g of the bead-shaped photocatalytic composition of Example 2 and 50 g of chickpeas were placed in a 100 ml transparent container containing 50 ml of distilled water, and UV LED light was continuously irradiated using a UV LED light source. The condition after 7 days was observed. The UV LED light was irradiated between 8:00 and 18:00 and was turned off between 18:00 and 8:00 the following morning. Distilled water alone was used as a control. The temperature setting during the experiment was 23°C. After the experiment, the growth of bacteria in the chickpeas in the UV LED light irradiation area and the control area was also observed.

[0129] Experimental results: Figure 16(a) shows a photograph of the control group 7 days after the start of the experiment. Figure 16(b) shows a photograph of the UV LED light irradiation group 7 days after the start of the experiment. The arrow in Figure 16(b) points to the bead-shaped photocatalytic composition of Example 2. Figure 17(a) shows a photograph of the proliferation of nuisance bacteria in chickpeas in the control group, and Figure 17(b) shows a photograph of the proliferation of nuisance bacteria in chickpeas in the UV LED light irradiation group. The white areas in the photograph in Figure 17 indicate areas where nuisance bacteria are present, and colorless areas indicate areas where nuisance bacteria are not present.

[0130] As shown in Figures 16(a) and 17(a), a large number of bacteria grew in the distilled water in the control area, causing it to become cloudy. In contrast, as shown in Figures 16(b) and 17(b), no bacterial growth was observed in the UV LED light-irradiated area using the photocatalytic composition of Example 2, and the distilled water remained clear even after the experiment. This confirmed that the photocatalytic composition of Example 2 can be used to sterilize microorganisms.

[0131] Example 5 The photocatalytic composition of Example 5 was produced using silica derived from diatom (Chaetoceros gracilis) as the silicon source material. The raw materials are listed in Table 7 below. The production process of the photocatalytic composition of Example 5 was the same as that of Example 1. [Raw materials] [Table 7]

[0132] [Silica extraction process from diatoms] Figure 18 shows the process for extracting silica from diatoms. Diatom (Chaetoceros gracilis) was purchased from Yanmar Co., Ltd. 1 × 10 8 500 ml of algae liquid (cell / ml) was placed in an alumina container and dried by heating at 120°C for 24 hours. After that, 10 g of diatom-derived silica was obtained by sintering in air at 300°C for 2 hours, 600°C for 5 hours, and 300°C for 2 hours.

[0133] Example 6 The photocatalytic composition of Example 5 was produced using ascorbic acid as a reducing organic material supplying material. The raw materials are shown in Table 8 below. The ascorbic acid and iron salt were mixed in a 1:1 ratio (1 g of ascorbic acid + 1 g of iron salt). The production process of the photocatalytic composition of Example 6 was the same as the production process of Example 1. [Raw materials] [Table 8]

[0134] [Experimental Example 10: Decomposition effect of harmful substances by photocatalytic composition irradiated with visible light] In order to verify the effect of the photocatalytic reaction of the photocatalytic compositions of Examples 5 and 6 on decomposing harmful substances, a methylene blue decomposition experiment was carried out using a visible light LED that emits violet to blue light (380 to 495 nm). Experimental Method: 50 mg of the powdered photocatalytic composition of Example 5 or 6 was added to 10 ml of methylene blue solution (5000 ppm methylene blue solution diluted 1000 times with water to 5 ppm), and the mixture was continuously irradiated with LED light (10,000 lux) for 4 hours to measure the decomposition rate of methylene blue. A dark condition without light irradiation was also used as a control.

[0135] Experimental results: Figures 19 and 20 show the experimental results for each photocatalytic composition in Examples 5 and 6. Figures 19(a) and 20(a) show the experimental results for each photocatalytic composition in graph form. Figures 19(b) and 20(b) show photographs of the LED-irradiated and control solutions for each photocatalytic composition after the experiment (4 hours after the start of the experiment).

[0136] As shown in Figures 19(a) and 20(a), methylene blue was not decomposed in the control group under dark conditions, and as shown in the photographs in Figures 19(b) and 20(b), the solution in the control group remained the color of methylene blue (blue).

[0137] In contrast, in the light irradiation sections using each photocatalyst composition, methylene blue was decomposed and its concentration decreased by continuous irradiation with purple to blue LED light, as shown in Figures 19(a) and 20(a). Also, as shown in the photographic images in Figures 19(b) and 20(b), in the light irradiation sections using each photocatalyst composition, the color of the solution became transparent, indicating that methylene blue was decomposed.

[0138] Therefore, it was found that the photocatalytic compositions of Examples 5 and 6 exhibited a strong photocatalytic reaction to purple to blue LED light (visible light), and were excellent in the decomposition effect of harmful substances such as methylene blue. The photocatalytic compositions in Examples 5 and 6 are made from algae that can be mass-produced. These algae are known to absorb large amounts of carbon dioxide (CO2). Therefore, in addition to this, there is hope for business possibilities for applying the functions and active ingredients of algae to various industrial applications. New industries utilizing algae are expected to emerge. Algae are expected to contribute to achieving carbon neutrality through photosynthesis and to achieving SDGs "GOAL 13: Take urgent action to combat climate change." [Industrial Applicability]

[0139] The photocatalyst disclosed herein is expected to be widely used for sterilization and organic matter decomposition in a wide range of fields, including food, medicine, public health, agriculture, and environmental cleanup.

[0140] This application claims priority based on Patent Application No. 2021-016944, filed with the Japan Patent Office on February 4, 2021, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A photocatalytic glass composition that exhibits catalytic activity under visible light, the glass material is produced by mixing raw materials containing a glass material including a reducing organic substance having the effect of reducing trivalent iron to divalent iron, an iron supply raw material, and a silicon supply raw material, and by carrying out a heat treatment in a reducing atmosphere at a heating temperature of 900°C or more for a heating time of 12 minutes or more to melt the raw materials, and by cooling the resulting melt to vitrify the glass material; the reducing organic substance contains at least one of polyphenols and ascorbic acid, the polyphenols are one or more compounds selected from chlorogenic acid, caffeic acid, tannic acid, and catechin, or a compound having one or more of the compounds in the molecule; the iron supply material contains at least one of a divalent iron compound and a trivalent iron compound, The mixing ratio of the reducing organic substance to the silicon supplying material is 5 parts by weight or more and 99 parts by weight or less of the silicon supplying material, calculated as the weight of silicon element, per 100 parts by weight of the dry weight of the reducing organic substance; A photocatalytic glass composition, wherein the mixing ratio of the reducing organic substance and the iron supplying material is 0.1 parts by weight or more and 10 parts by weight or less of the iron supplying material, calculated as the weight of iron element, per 100 parts by weight of the dry weight of the reducing organic substance.

2. 2. The photocatalytic glass composition according to claim 1, wherein said silicon supplying material comprises a plant selected from the group consisting of grasses, ferns, and algae, or a processed product of said plant.

3. 3. The photocatalytic glass composition according to claim 1, wherein the raw material for supplying the reducing organic substance is any one of roasted coffee beans, tea leaves, fruit juice, and dry distillation liquid of plants.

4. A deodorant comprising the photocatalytic glass composition according to any one of claims 1 to 3, which exhibits catalytic activity when exposed to visible light.

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