JP2005288302A - Liquid treatment method using titanium oxide combined woody carbonized product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid treatment method using a titanium oxide combined woody carbonized product by which organic material contained in liquid to be treated is efficiently decomposed by efficiently exhibiting the photocatalytic activity of titanium oxide present in the woody carbonized product. <P>SOLUTION: The liquid treatment method is characterized in that the liquid to be treated containing organic material is irradiated with ultrasonic wave in the presence of the titanium oxide combined woody carbonized product and hydrogen peroxide and the organic material is decomposed as a result. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for treating a liquid, and more particularly, to a method for treating water containing an organic substance.

  In recent years, a photolysis catalyst in which titanium dioxide is supported on activated carbon or the like is known as a catalyst for environmental purification or deodorization of a refrigerator. For example, Patent Document 1 describes a photocatalytic activated carbon based on a titanium oxide-supported wood carbide that has been carbonized and activated in the presence of a Ti component, specifically, an activated carbon precursor such as a novolak resin. After uniformly mixing the organic substance and the Ti-containing solution, the photocatalytic activated carbon is manufactured by carbonization by calcination and activation treatment. Moreover, it has been shown that these can be used in fields requiring elastic modulus and strength by producing them in a fibrous form. However, activated carbon precursor organics such as novolak resin do not recognize the importance of the cell walls and cell lumens inherent to wood and the like, and a catalyst with high photolysis efficiency and economically advantageous is obtained. I can't.

  Patent Document 2 discloses a composite material for environmental purification in which a wood-based fired carbide obtained by firing a wood-based material in an inert gas atmosphere and titanium oxide are combined. Further, it is described that nitrogen oxide or the like can be adsorbed using this complex and can be rendered harmless by light. However, this technique also does not recognize that the cell walls and cell lumens inherent to wood or the like and the pretreatment thereof are important, and does not indicate that a catalyst with high photolysis efficiency can be obtained. Furthermore, due to the organic residues remaining in the titanium oxide gel, catalytic ability with high decomposition efficiency is not obtained.

Under such circumstances, one of the present inventors (Saka) has a novel complex in which titanium oxide and biomass carbide are complexed at the cellular level and a method for producing the same, assuming that the catalyst has high decomposition efficiency. Have been filed earlier (Patent Document 3).
JP-A-8-332378 JP-A-10-28861 JP 2000-254495 A

  In the decomposition of an organic substance using a photocatalyst, it is necessary to develop photocatalytic activity by supplying light energy such as ultraviolet rays to the photocatalyst. However, in the decomposition of organic substances in a liquid using a photocatalyst, absorption of ultraviolet light (light energy) by the liquid itself or scattering of ultraviolet light by a microdispersion contained in the liquid occurs, so that light energy is efficiently applied to the photocatalyst. It may not be possible to donate. As a result, there is a problem that the photocatalytic activation is hardly exhibited and the decomposition efficiency is lowered. In particular, in the titanium oxide composite wood carbide previously proposed by one of the inventors (Saka), titanium oxide is compounded at the cellular level, and titanium oxide is also present inside the wood carbide, so that it is irradiated from the outside. There is a possibility that ultraviolet rays cannot reach titanium oxide.

  The present invention has been made in view of such circumstances, and in a liquid treatment method using a titanium oxide composite wood carbide, the photocatalytic activity of titanium oxide existing inside the wood carbide is efficiently expressed, It is an object of the present invention to provide a liquid processing method for efficiently decomposing organic substances contained in a processing liquid. In the presence of titanium oxide composite wood carbide and hydrogen peroxide, the liquid treatment method of the present invention that has been able to solve the above-described problems is to irradiate the liquid to be treated containing organic matter with ultrasonic waves, thereby treating the organic matter. It is characterized by decomposing. As the titanium oxide composite wood carbide, it is preferable to use one in which titanium oxide is generated in the cell wall of the wood carbide. In addition, the present invention can be suitably applied to treat organic matter-containing wastewater or organic matter-containing wastewater.

First, the present invention has a first feature in that a titanium oxide composite wood carbide is used.
The titanium oxide composite wood carbide used in the present invention is a composite of titanium oxide capable of exhibiting a decomposition action utilizing photocatalytic activity and a wood carbide exhibiting an adsorption action. By decomposing (proximity), the decomposition efficiency of organic substances can be further increased.

  Next, the present invention has a second feature in that ultrasonic waves are used as an energy supply means for imparting photocatalytic activity to titanium oxide complexed with wood carbide. It is known that when a liquid such as an aqueous solution is irradiated with ultrasonic waves, the dissolved gas becomes bubbles. At this time, it has been confirmed that a light emission phenomenon (sonoluminescence) having an emission spectrum in the ultraviolet region occurs. In the present invention, light energy is indirectly supplied to titanium oxide by utilizing light emission (ultraviolet light) generated when bubbles are generated by irradiating ultrasonic waves without externally irradiating titanium oxide with ultraviolet rays. There is a second feature. The vibration of the ultrasonic wave can reach the inside of the wood carbide, and a light emission phenomenon occurs inside the wood carbide. As a result, light energy can be imparted to titanium oxide compounded inside the wood carbide, and titanium oxide can exhibit photocatalytic activity. In particular, it is considered that a light emission phenomenon occurs also in the vicinity of titanium oxide compounded inside the wood carbide, which is suitable for imparting photocatalytic activity to titanium oxide compounded inside the wood carbide.

  Third, the present invention is characterized in that hydrogen peroxide is further used in combination to increase the decomposition efficiency of organic matter. This is because hydrogen peroxide exhibits an oxidizing action on organic substances, and in particular, hydroxyl radicals generated from hydrogen peroxide exhibit a very strong oxidizing action and decompose organic substances in the liquid to be treated.

  According to the present invention, organic substances in the liquid to be treated can be efficiently decomposed without irradiating ultraviolet rays from the outside. Further, there is no need for an apparatus for generating ultraviolet rays, and there are few restrictions on the shape of the decomposition processing apparatus.

The liquid treatment method of the present invention is characterized in that in the presence of a titanium oxide composite wood carbide and hydrogen peroxide, the liquid to be treated is irradiated with ultrasonic waves to decompose the organic matter. In the present invention, “titanium oxide” means “titanium dioxide (TiO ₂ )” unless otherwise specified.

  First, the titanium oxide composite wood carbide used in the present invention will be described. The titanium oxide composite wood carbide used in the present invention is not particularly limited as long as it is a composite of titanium oxide that exhibits a decomposition action by a photocatalyst and wood carbide that exhibits an adsorption action. The aspect in which titanium oxide is compounded with wood carbide is not particularly limited, but it is preferable that titanium oxide and wood carbide are complexed at the cellular level. For example, titanium oxide is formed on the cell surface of wood carbide. And an embodiment in which titanium oxide is produced in the cell lumen of the wood carbide, and an embodiment in which titanium oxide is produced in the cell wall of the wood carbide. This is because by synthesizing at the cellular level as described above, the synergistic effect of photodegradation and adsorption is enhanced. Among the above composite modes, a mode in which titanium oxide is generated in the cell wall of the wood carbide is a mode to which the present invention can be applied most effectively. This is because, in an embodiment in which titanium oxide is generated in the cell wall of the wood carbide, it is difficult for ultraviolet rays to reach the titanium oxide in the cell wall, and the photocatalytic activity is difficult to be expressed.

  The method for producing the titanium oxide composite wood carbide is not particularly limited, and examples thereof include the method disclosed in Japanese Patent Application Laid-Open No. 2000-254495 previously filed by the present inventor (Saka). For example:

  In general, one method for preparing a metal oxide catalyst is a sol-gel method. In the sol-gel method, a sol agent is added to metal organic and inorganic compounds to form a sol solution. After the sol is supported on a carrier, it is solidified as a gel and a metal oxide solid is formed by heat treatment or the like. Is the method.

  Metal alkoxide M (0R) n, where M is a metal atom such as Si, Ti, Ba, Zr, R is an alkyl group (although there is no particular limitation, it usually has 1 to 20 carbon atoms), and n is an oxidation of the metal For example, a mixed solution of metal alkoxide-alcohol-water is used as a starting material. When metal alkoxide is hydrolyzed and polycondensed at 25 to 80 ° C., metal oxide fine particle colloids are formed, the solution becomes a sol, and further proceeds to a wet gel. This gel becomes glass or ceramics when heated. In the case of inorganic composite of wood, for example, a metal alkoxide-alcohol-acetic acid system is used with water in a wood sample piece (abbreviated as a test piece) as an initiator. The specimen is immersed for a predetermined time under reduced pressure or normal pressure to produce a metalloxane (metal oxide) gel in the wood cells, thereby preparing an inorganic composite wood.

  In the research conducted by the inventors up to now (for example, APAST, No. 30, pp10-14, 1999, 1), the distribution of inorganic substances (metal oxides) in the wood cell is based on the type of metal alkoxide used and the moisture content of the wood. It was found by observation with a scanning electron microscope that the difference was due to the difference in the above. That is, the intracellular distribution of the inorganic substance is completely different between the case where the humidity control specimen is used and the case where the saturated specimen is used, even if the same metal alkoxide is used. FIG. 1 shows the type of inorganic distribution (in the figure, the white part shows the part without inorganic substance, and the colored part shows the part where inorganic substance exists), and Table 1 shows the gel composition of the produced inorganic substance. And the type of the distribution are shown for a reaction system of titanium alkoxide (or titanium chelate) / alcohol.

TPT: Tetraisopropoxy Titanium TBT: Tetra-n-Butoxy Titanium TOT: Tetrakis (2-ethylhexyloxy) Titanium TAA: Diisopropoxybis (acetylacetonato) Titanium TAT: Di-n-Butoxybis (Triethanolaminato) Titanium

  In Table 1, the humidity control specimen has a moisture content below the fiber saturation point, and only the bound water is present in the wood cell wall. In contrast to the saturated specimen, free water is present in the cell lumen in addition to water containing water. As described above, when samples having different water molecule distributions are used, composite wood having different inorganic distributions in combination with titanium alkoxide (or titanium chelate) can be obtained. An absolutely dry specimen (simply abbreviated as a dry specimen) is one in which bound water is substantially absent. Both the humidity control specimen and the dry specimen are obtained by drying, and the moisture level is determined by adjusting conditions such as drying temperature, pressure, and time. The moisture of the humidity control specimen in Table 1 is 20 to 28% by weight, and the moisture of the saturated specimen is about 150% by weight.

  First, in order to selectively produce a titanium compound only in the cell wall (type [I]), a kind of titanium chelate (diisopropoxybis (acetylacetonato) titanium (TAA)) or di-n-butoxybis (tri Ethanolamine) titanium (TAT) may be added to the humidity control specimen. On the other hand, with saturated specimens, there is also water in the cell lumen, so as in type [IV], the distribution in which the titanium compound is present throughout the cell wall, cell lumen, and outside of the specimen (cell surface), etc. It becomes. In these systems, the distribution of titanium oxide is close to the distribution of water contained in the specimen. However, among the titanium alkoxides, tetraisopropoxytitanium (TPT) does not have the distribution of type [I] even when a humidity control specimen is used, but it is intracellular as in types [II] and [III]. The distribution fills or surrounds the cavity. On the other hand, when a saturated specimen is used, a titanium compound cannot be produced in the cell lumen or the cell wall, and only titanium oxide covers the outside of the specimen. However, when tetra-n-butoxytitanium (TBT) or tetrakis (2-ethylhexyloxy) titanium (TOT) is used among titanium alkoxides, the cell wall as seen in type [V] in the humidity control specimen. At the same time, titanium compounds can be produced in the cell lumen.

  The intracellular distribution of these titanium compounds appears to depend on their hydrolysis rate and the subsequent solation rate due to the polycondensation reaction. In particular, when producing titanium oxide composite wood carbide necessary for photodegradation of chemical components in an adsorbed state, the titanium compound is maximized in the composite, rather than simply being composited into wood. It is very important to complex to the appropriate site, i.e. cell lumen and / or cell wall and / or cell surface, to show an effect.

  In order to synthesize a sol solution of titanium oxide, titanium alkoxide or titanium chelate can be used as a titanium compound to be used. The titanium alkoxide is di, tri, or tetraalkoxy titanium, preferably tetraalkoxy titanium. As an alkoxy group, a C1-C12 alkoxy group is preferable. Specific examples of the titanium alkoxide include TPT, TBT, TOT and the like. Examples of the titanium chelate include TAA and TAT. In addition to the titanium component, if necessary, one or more of V, Cr, Fe, Co, Ni, Mn, Zn, Zr, Mo, Cu, Ag, Au, Pt, Pd, Si, B, etc. It is also possible to combine them. As these compounds, nitrates, chlorides, acetates and the like are preferable, and they are used in an aqueous solution thereof or in a solution state using an organic solvent, and become an oxide after firing.

  The wood material used as a raw material for supporting titanium oxide in the present invention has a structure having at least a cell wall and a cell lumen, may have a cell surface, and cells comprising the cell wall and the cell lumen are A plurality of them may be present, and those having a large number of cell lumens capable of complexing with titanium oxide are preferable. Each cell is preferably in communication with outside air. Specific examples of the woody material include wood powder such as conifers and hardwoods, chips, tree branches, wood, wood fibers, bark, berries, shells, grains, grasses, etc., which are obtained by processing them. All woody materials having the above-mentioned structure, such as papers and fibers such as cotton and hemp, are included. The shape of the woody material is not particularly limited, but is preferably wood flour or a thin piece of wood in consideration of the extraction / drying / impregnation process. The size of the piece of wood is not particularly limited, but is preferably 1 to 100 mm in maximum length, and particularly preferably 10 mm or less. The size of the wood flour is 0.001 to 10 mm, preferably 0.01 to 1 mm, particularly preferably 0.05 mm or less. In addition, these raw materials may not be made into wood powder from the beginning, but may be pulverized to form the above wood powder after forming the titanium oxide composite woody material or after firing.

  Even if the wood material is used as it is, the ratio of the metal oxide compounded to the cell lumen and the cell inner wall is extremely low, and an appropriate catalyst cannot be obtained. As a woody material, when producing titanium oxide in the cell wall, it is better to use a conditioned specimen and titanium chelate, and when producing titanium oxide in the cell lumen and / or cell surface, Use a conditioned specimen and titanium alkoxide. However, when a titanium oxide sol is used, any of a dry specimen, a humidity control specimen, and a saturated specimen may be used. The moisture content of the humidity control specimen is usually 28% by weight (tissue saturation point), preferably 20 to 28% by weight. Examples of the specimen include a dried sample, a sample extracted with a solvent, a sample extracted with a solvent and dried, a sample conditioned, and a sample saturated with water. When dried or solvent extracted, the metal oxide gel is easily combined with the cell lumen and the cell inner wall. Extraction solvents for wood materials include ketones such as acetone and methyl ethyl ketone; alcohols such as methanol, ethanol and isopropanol; ethers such as methyl ether, ethyl ether and isopropyl ether; esters such as methyl acetate and ethyl acetate; water, and these It is a mixture of Preferred is acetone or a mixture of acetone and water. As the extraction operation, extraction may be performed a plurality of times with the different solvents. The extraction temperature, time and pressure are not particularly limited, and the extraction is preferably performed at normal pressure and at the normal pressure boiling point for 1 to 24 hours, preferably 3 to 12 hours. The woody material after extraction may be impregnated with the metal oxide sol as it is, but is preferably dried. The drying conditions are not particularly limited, and may be 80 to 150 ° C., normal pressure or reduced pressure, and may be dried for 1 to 48 hours, preferably 3 to 24 hours to be conditioned or dried. By the above treatment step, a wood material in which titanium oxide is easily combined with the cell lumen, the cell wall, and the cell surface is obtained.

  The titanium alkoxide, titanium chelate, titanium oxide sol, or a mixture thereof (the above is referred to as a titanium oxide raw material) is mixed with the wood material and combined by impregnation or the like. The mixing ratio of the wood material and the titanium oxide sol is not particularly limited, but it is preferable that the wood material is sufficiently immersed in the titanium oxide sol solution. The impregnation may be performed at 50 ° C. or less, preferably near normal temperature, under normal pressure, under pressure, or under reduced pressure, and may be performed for 1 to 48 hours, preferably 3 to 24 hours, standing, shaking, or mechanical or ultrasonic. By agitation. After impregnation, unnecessary titanium oxide raw materials are separated by centrifugation, filtration, adsorption, or the like. When impregnated with a sol solution, the sol may be gelled by an operation such as addition to an aqueous ammonium acetate solution after the impregnation. The wood material containing the gel content is preferably dried. There are no particular restrictions on the drying conditions, but preferably in the presence of an inert gas, the temperature may be 80 to 150 ° C., normal pressure or reduced pressure, and the drying is performed for 1 to 48 hours, preferably 3 to 24 hours.

  The titanium oxide composite wood material thus obtained has an inert gas flow (in the absence of oxygen) of 250 to 1,500 ° C., preferably 400 to 600 ° C., particularly preferably 450 to 550 ° C. After heating for 1 to 10 hours, preferably 0.5 to 2 hours for carbonization and crystallization, 300 to 1 in the presence of an oxidizing gas (for example, oxygen gas or air) or in an air stream The titanium oxide composite wood carbide is obtained by heating at 1,000 ° C., preferably 350 to 600 ° C., more preferably 400 to 500 ° C. for 1 minute to 1 hour, preferably 3 to 20 minutes. It is used as an excellent photocatalyst. By performing such a treatment, titanium oxide is compounded in the cell lumen and / or cell wall, so that the adsorption site of the chemical component and the active metal catalyst site can be present in large quantities in the same or very close proximity. It can efficiently decompose and desorb chemical components, adsorb and decompose new chemical components.

The titanium oxide complexed with the wood carbide may be anatase type, rutile type, procite type, amorphous type, or a mixture thereof. Preferably, an anatase type is mainly used, and a rutile type containing 0 to 50% by weight, preferably 0 to 30% by weight is used. Moreover, content of the titanium oxide in a titanium oxide composite wood carbide is 0.1-90 mass% as titanium dioxide, Preferably it is 1.0-87 mass%, More preferably, it is the range of 10-85 mass%. The present invention is also characterized in that the content of titanium oxide can be 40% by mass or more, 50% by mass or more, and further 60% by mass or more as titanium dioxide. If the content of titanium oxide is less than 0.1% by mass, the effect of photocatalysis is insufficient, and if it is more than 90% by mass, the effect of adsorption of chemical components by the wood carbide decreases, the mechanical properties decrease, etc. . The specific surface area of the titanium oxide composite wood carbide, 10~2,000m ² / g, preferably 100 m ² / g or more, further preferably 500 meters ² / g or more. When the specific surface area is less than 10 m ² / g, the chemical component to be treated is insufficiently adsorbed.

  The titanium oxide composite wood carbide used in the present invention may be a powder, a coarsely crushed body, or a molded body depending on the purpose of use. The particle size of the powder is not particularly limited, and examples thereof include the size of the wood material powder, and the powder may be finely pulverized so as to increase the photolysis catalytic activity. In addition, the molded body can have a granular shape, a honeycomb shape, a plate shape, a corrugated plate shape, a ring shape, a fiber shape, or the like. You may apply | coat the powder of a titanium oxide composite wood carbide to a ceramic, glass, and a metal surface.

  The liquid treatment method of the present invention decomposes the organic matter by irradiating the liquid to be treated containing the organic matter with ultrasonic waves in the presence of the titanium oxide composite wood carbide obtained as described above and hydrogen peroxide. . Specifically, for example, a mode in which the titanium oxide composite wood carbide obtained as described above and hydrogen peroxide are added to a liquid to be treated containing an organic substance and ultrasonic waves are applied to the liquid to be treated is mentioned. Can do.

  At this time, the amount of hydrogen peroxide added can be appropriately selected according to the concentration of the organic substance in the liquid to be treated, but usually the hydrogen peroxide concentration in the liquid to be treated is about 0.01 to 10%. It is a preferred embodiment. Although the addition amount of the titanium oxide composite wood carbide is not particularly limited, it is preferably 10 mg to 1000 mg, more preferably 50 mg to 500 mg with respect to 1 L of the liquid to be treated. In addition, the present invention is suitable for treating a liquid to be treated having an organic substance concentration of about several hundred ppm.

  The conditions of ultrasonic irradiation used in the liquid processing method of the present invention can be determined as appropriate. For example, the following conditions are preferable. The frequency of the ultrasonic wave is not particularly limited, but is preferably 10 kHz to 10 MHz, and more preferably 20 kHz to 1000 kHz. Irradiation intensity can be appropriately set according to the amount of treated water of the liquid to be treated, but 100 W to 1000 W is usually sufficient. What is necessary is just to set the irradiation time of an ultrasonic wave suitably according to the density | concentration of the organic substance in a to-be-processed liquid, and the processing amount of a to-be-processed liquid. In addition, the temperature of the liquid to be treated at the time of ultrasonic irradiation may be room temperature, but it is also a preferable aspect that the temperature is about 10 ° C to 70 ° C. This is because the generation efficiency of hydroxyl radicals generated by decomposition of hydrogen peroxide can be increased.

  An organic substance or a derivative thereof that can be decomposed by the liquid processing method of the present invention is not particularly limited, and examples thereof include aldehydes such as formaldehyde, acetaldehyde, and propylaldehyde; acetone, methyl ethyl ketone, methyl isobutyl ketone, and acetophenone. Ketones such as benzophenone; saturated or unsaturated hydrocarbons such as methane, ethane, propane, butane, ethylene, propylene, butene, cyclohexane, acetylene, butadiene; methyl halide, methylene dihalide, trihalomethane, tetrahalogen methane, ethylene di Alkyl halides such as halides, trihaloethanes, vinyl halides, vinylidene dihalides, trihaloethylenes, and various chlorofluorocarbons (including halogens such as fluorine, chlorine, bromine, iodine, and ), Halogen compounds such as dioxins and PCBs; unsaturated hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene, styrene and benzpyrene; indoles such as indole and skatole; phenols; Nitrogen compounds such as nitrogen oxides, ammonia, monomethylamine, dimethylamine, trimethylamine, pyridine; various sulfur compounds such as hydrogen sulfide, dimethyl sulfide, dimethyl disulfide, methyl mercaptan, ethyl mercaptan, sulfur oxide; methanol, ethanol, isopropanol, Examples include alcohols such as butanol; aliphatic carboxylic acids such as formic acid, acetic acid, butyric acid, valeric acid, and isovaleric acid.

  In addition, the liquid to be treated which is the subject of the present invention is not particularly limited as long as it is a liquid containing the above-mentioned organic matter. be able to.

[Preparation of titanium oxide composite wood carbide]
(1) Preparation of Titanium Oxide Gel Add 20 g of tetraisopropyl titanate (TPT) to 100 ml of 10% dimethylamine aqueous solution, stir while heating until the solution becomes transparent, and then stir at room temperature for 6 hours. Obtained. This sol solution was gelled by adding 5% aqueous ammonium acetate solution, and then treated at 105 ° C. for 24 hours. The obtained sol was pulverized to 0.08 mm or less, and then heat-treated in a nitrogen atmosphere at 480 ° C. for 1 hour, and then in an air atmosphere at 430 ° C. for 7 minutes to obtain anatase-type crystal titanium oxide.

(2) Preparation of titanium oxide composite wood carbide 50 g of wood flour was put into 500 ml of distilled water and subjected to swelling treatment at room temperature for 3 days. Then, 20%, 50%, 70%, 90%, and 99.5% ethanol aqueous solutions were added in order, and each was stirred for 30 minutes at room temperature. The stirring process for 2 minutes was performed twice. Thereafter, the wood flour was taken out and impregnated in 500 ml of a 10% tetraisopropyl titanate (TPT) / ethanol solution and stirred. After impregnation for 2 hours, the solution was added to 500 ml of ethanol, and the stirring treatment was repeated twice for 5 minutes. Then, this wood flour was put into 500 ml of distilled water and gelled. It was taken out after 1 hour and dried at 60 ° C. for 24 hours and at 105 ° C. for 24 hours to obtain a titanium compound composite wood powder. The obtained dry titanium compound composite wood flour was carbonized in a rotary carbonization furnace at 430 ° C. for 1 hour in a nitrogen atmosphere. The obtained carbide was further activated at 430 ° C. for 7 minutes in an air atmosphere to obtain a titanium oxide composite wood carbide.

Experimental example 1
Add 40 ml of distilled water and 10 ml of 30% hydrogen peroxide to an Erlenmeyer flask to prepare 50 ml of 6% hydrogen peroxide, and add 4.6 mg of 36% formaldehyde aqueous solution so that the concentration of formaldehyde is 100 ppm. It was. This Erlenmeyer flask was placed in an ultrasonic cleaner. Titanium oxide composite wood carbide was added thereto so that the amount of titanium oxide added was 10 mg. The time when the titanium oxide composite wood carbide was added was taken as the measurement start time, and ultrasonic irradiation was started 120 minutes after the start of the measurement. The ultrasonic frequency was 40 kHz and the strength was 200 W. In order to prevent the influence of light, the test was conducted under light shielding. The test solution was sampled every hour and the formaldehyde concentration was measured. The formaldehyde concentration was measured with a gas chromatography mass spectrometer QP5000A (Shimadzu Corporation).
The results are shown in FIG. For comparison, ultrasonic irradiation was performed on 100 ppm formaldehyde aqueous solution (control), a non-complexed wood carbide added to the formaldehyde aqueous solution, and a titanium oxide gel not combined in the formaldehyde aqueous solution. The results are shown together in FIG.

Experimental example 2
The test was performed in the same manner as in Experimental Example 1 except that no aqueous hydrogen peroxide solution was added. The results are shown in FIG.

  From FIG. 2, it can be seen that in the present invention example in which an aqueous formaldehyde solution was irradiated with ultrasonic waves in the presence of titanium oxide composite wood carbide and hydrogen peroxide, the concentration of formaldehyde was significantly reduced and formaldehyde was efficiently decomposed. . Further, comparing FIG. 2 with FIG. 3, it was revealed that the decomposition rate of formaldehyde can be remarkably increased by adding hydrogen peroxide.

  The present invention is suitable for the treatment of liquids containing organic substances, particularly for decomposing harmful organic substances contained in water and sewage, factory wastewater, and the like.

Illustration of composite aspect of titanium oxide composite wood carbide Graph showing formaldehyde concentration change Graph showing formaldehyde concentration change

Explanation of symbols

1: cell surface, 2: cell wall, 3: cell lumen, 4: peripheral edge of cell lumen

Claims (2)

  A liquid treatment method comprising decomposing the organic matter by irradiating a liquid to be treated containing the organic matter with ultrasonic waves in the presence of a titanium oxide composite wood carbide and hydrogen peroxide.   2. The liquid treatment method according to claim 1, wherein the titanium oxide composite wood carbide is one in which titanium oxide is generated in a cell wall of the wood carbide. 3.

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