JP2009125743A - Decomposition method and apparatus for voc substance in water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decomposition method and apparatus exhibiting high decomposing property of a VOC substance, no adverse reaction such as occurrence of a harmful substance, and high completeness degree, in a technique for decomposing and detoxifying a VOC substance in water containing it. <P>SOLUTION: The decomposition method and apparatus are capable of obtaining harmless water by light-focusing and illuminating ultrashort pulsed-laser 2 of 1,000 picoseconds to 50 femtoseconds in VOC substance-containing water 8 in a transparent glass tubing part 5 and cutting and decomposing a bonding link of a molecule of the VOC substance in the VOC-containing water. The method is verified to be a clean technique which can completely cut the molecular bonding link of the VOC substance by the ultrashort pulsed-laser illumination and does not generate a harmful by-product. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for detoxifying harmful substances present in water, and more particularly, to a method and apparatus for decomposing VOC substances in water.

Currently, combustion decomposition methods, adsorption-type removal methods, catalytic combustion methods, thermal storage-type decomposition methods, and the like are performed as methods for removing VOC substances and detoxifying them.
The following documents should be suggested or referred to regarding technologies for detoxifying harmful substances.
JP 2006-110117 A JP 2006-71492 A JP-A-2005-81259 JP 2004-24942 A JP2001-300256 JP 2000-126549 A JP-A-7-8745 Note that, in the general description of the document, the quotations from the document and the description thereof use the expressions used in the document as they are.

“Patent Document 1” discloses a robot that specifies a harmful substance using a laser and further detoxifies the harmful substance.
In paragraph number “0012” of “Patent Document 1”, “... the robot body is irradiated with a laser to identify harmful substances and means for identifying harmful substances, and the laser is irradiated over a wide area. By measuring the concentration distribution in this way, the hazardous substance source identification means with the highest concentration of the harmful substance as the source is further irradiated with a laser other than the laser to harm the harmful substance. A laser device having detoxification processing means for processing, a photographing means for photographing the surroundings of the robot body, a remote operation signal for the robot body, and a video data photographed by the photographing means. -A transmitter / receiver for transmitting data, including: organisms such as carbon bacteria, botulinum bacteria, plague bacteria, cebu, ricin, smallpox virus, tunusia bacteria, VX gas, sarin , Soman, Star -. Dogasu, lewisite, chemical agents such as hydrogen cyanide and the like ... ", to be disclosed.
Note that “Patent Document 1” does not describe a laser medium, a wavelength, a transmission form, an output, or the like related to a laser beam used.

The related part of “Patent Document 2” is to irradiate a laser to a fine particle component to remove the gas component in the gas and analyze only the fine particle component, and to remove the volatile organic compound of the fine particle component. Paragraph number “0010” of “Patent Document 2”, which is a disclosure relating to an apparatus in which a vaporized volatile organic compound is ionized by irradiating a laser to a vaporized volatile organic compound, In a third aspect of the invention, the plasma apparatus in the second decompression chamber is a laser apparatus that irradiates the fine particle component with laser light having a wavelength in the range of 180 to 400 nm to vaporize the volatile organic compound of the fine particle component. The plasma device in the third decompression chamber is a laser device that irradiates and ionizes a vaporized volatile organic compound with a laser beam in the range of 180 to 400 nm. In the measuring device ”.

"Patent Document 3" discloses a laser decomposing apparatus that irradiates a region containing harmful components with a laser having a specific wavelength that excites water vapor, and decomposes harmful substances using the excited high energy. And disclosures regarding methods.
Paragraph No. “0007” of “Patent Document 3” includes “... a laser device that irradiates laser light that excites water vapor, and is caused by water vapor that is in a highly excited state by laser light irradiation. Decompose the object to be decomposed ... ".
Also, paragraph number “0011” of “Patent Document 3” states that “... the excitation wavelength of water vapor is one or more specific wavelengths in the wavelength range of 1100 to 1160 nm, 1340 to 1500 nm, and the laser. Amplifying light, irradiating a region where the decomposition target is present, bringing water vapor existing in the region into a high energy state, and decomposing the decomposition target.

“Patent Document 4” is a disclosure relating to a purification technique using a laser that can directly purify contaminated soil at a contaminated site.
In the paragraph number “0005” of “Patent Document 4”, “... a large facility such as an incinerator is used if the laser beam is directly irradiated onto the surface of contaminants typically contaminated soil. "If a small and light laser transmitter such as a semiconductor laser is used, equipment can be brought into the contaminated site and the purification process can be carried out on the spot."
In addition, “Because the heating temperature by laser beam irradiation reaches 1,000 to 1,500 degrees Celsius, it is possible to remove dioxins, lead and the like as well as sterilization treatment against various germs. -Since the heating process by the beam is completed instantaneously, it can be returned to the original place without providing a cooling process.

  Further, in paragraph No. “0012” of “Patent Document 4”, “the laser oscillator 14 is composed of a semiconductor laser oscillator having a 10 kw class output, for example. The laser head 16 is connected by an optical fiber 24. An optical element such as a cylindrical lens is incorporated in the laser head 16, and the laser beam output from the laser oscillator 14 is provided. Are linearly beamed by the action of these optical elements. "

“Patent Document 5” discloses a method and an apparatus for disassembling a harmful substance such as dioxin in exhaust gas by providing a decomposition processing unit for irradiating a laser to an exhaust duct of exhaust gas generated in a waste incinerator. It is.
In the paragraph number “0004” of “Patent Document 5”, “... exhaust gas via heated CO ₂ by irradiating the exhaust gas generated in the exhaust gas generation source with CO ₂ laser light. In the method for decomposing harmful substances contained in the exhaust gas, the concentration of CO ₂ contained in the exhaust gas when the exhaust gas is irradiated with the CO ₂ laser light is set as the exhaust gas. It is configured to increase to a concentration higher than the concentration of CO ₂ contained in the exhaust gas generated from the gas generation source.

In addition, in the same paragraph number, “... the harmful substances contained in the exhaust gas through the heated CO ₂ by irradiating the exhaust gas generated at the source of the exhaust gas with CO ₂ laser light. In a harmful substance decomposition apparatus including a decomposition processing unit for decomposition, the concentration of CO ₂ contained in the exhaust gas when the decomposition processing unit irradiates the exhaust gas with CO ₂ laser light is increased to a predetermined value or more. It is disclosed that density increasing means are provided. "
In addition, in the paragraph number “0005” of “Patent Document 5”, “According to the above-described configuration, it is possible to decompose about 100% of dioxin contained in the exhaust gas, as is apparent from the experimental results described later. It is disclosed.

“Patent Document 6” discloses that when an exhaust gas from an incinerator or the like is irradiated with a CO ₂ laser, a harmful substance such as dioxin is efficiently heated between its decomposition temperatures.
In paragraph number “0004” of “Patent Document 6”, “... exhaust gas from an incinerator or the like is irradiated with CO ₂ laser light to be heated to a decomposition temperature of harmful substances such as dioxin, and the exhaust gas is exhausted. The apparatus of the present invention is characterized by decomposing harmful substances present in the gas, and the apparatus of the present invention includes an exhaust duct through which exhaust gas from an incinerator or the like flows, and a CO ₂ laser beam in the exhaust duct. , And a CO ₂ laser oscillator that closes the exhaust duct with CO ₂ laser light.

“Patent Document 7” is a disclosure of a method for suppressing a reduction in energy efficiency due to a reaction product while minimizing photon loss when decomposing a harmful gas by a laser.
In paragraph number “0007” of “Patent Document 7”, “... a device for removing harmful substances contained by irradiating a gas body with a laser, comprising a central plane mirror and a concave mirror around it. The laser reactors equipped with the multiple reflecting mirrors are arranged in multiple stages in series with the gas flow path, and the laser reactors are connected by a passage portion filled with a decomposition product absorbent. -It is possible to continuously remove harmful substances by continuously introducing gas into the downstream laser reaction vessel while removing decomposition products generated by photochemical reaction in the reaction vessel in the passage portion. It has been disclosed.

Environmental pollution such as air, water and soil is caused by environmental destruction such as excessive deforestation, production activities, consumption activities, etc., and most of them are man-made results.
Hazardous chemical substances that surround us include lead and mercury as heavy metals, hexavalent chromium compounds, cadmium compounds, nickel compounds and antimony compounds as metal compounds, arsenic, boron and fluorine as inorganic elements, and cyanide Compounds and the like.
Further, volatile organic chlorine compounds such as trichloroethylene, tetrachloroethylene, dichloroethylene, methylene chloride, carbon tetrachloride, and ethylene dichloride are exemplified.

Also, benzene and toluene as aromatic hydrocarbons, CFC (chlorofluorocarbon), halon, HFC (hydrofluorocarbon) or HCFC (hydrochlorofluorocarbon) as chlorofluorocarbons and alternative chlorofluorocarbons, Examples of carcinogenic substances include asbestos, MTBE (methyl-t-butyl ether), and other formaldehyde.
In addition, there is a type of chemical substance group called VOC (Volatile Organic Compound), although there are types overlapping with these.

Furthermore, VVOC (highly volatile organic compound) having a lower boiling point than the VOC and SVOC (semi-volatile organic compound) having a higher boiling point than the VOC may be simply referred to as VOC.
Including POM (particulate organic material) having a higher boiling point than SVOC, it may be referred to as TVOC (total volatile organic compounds).
Of course, the characteristics of VOC cannot be classified only by boiling point, but since there is no other proper classification method, VOC is generally classified by boiling point.

In WHO, the classification of VOCs by boiling point is defined as follows.
That is, a boiling point of 0-50 to 100 ° C. is defined as VVOC, a boiling point of 50-100 to 240-260 ° C. is defined as VOC, and a boiling point of 240-260 to 380-400 ° C. is defined as SVOC.
In the present invention, from VVOC having a low boiling point in the boiling point classification to SVOC having a high boiling point are referred to as VOC substances, and the VOC substance is particularly referred to in order to clearly distinguish it from a narrowly defined VOC.

VOC substances are organic compounds such as benzene and formaldehyde in the atmosphere, and are known as causative substances that cause photochemical air pollution together with NO _X and the like.
The hazard of VOC has two meanings.
The first aspect is the VOC substance as a direct harmful substance from the viewpoint of the effect on human health, and many of them have a harmful effect on the human body such as carcinogenicity, and as a causative substance of sick house syndrome It is a known hazard.
The second viewpoint is the harmfulness of the VOC substance as one of the causative substances that secondarily generate photochemical oxidants, SPM (floating particulate matter) and the like.
For example, it originates from groundwater contamination by aliphatic halogen compounds, and is an important substance group as soil contamination, production of trihalomethane in waterworks, air pollution, or indoor air pollution.

Examples of the VOC substance include alkanes, alkenes, aldehydes, ketones, aliphatic halogen compounds, aromatic hydrocarbons, terpenes, and compounds used as agricultural chemicals.
VOC substances that can analyze the concentration of the VOC substance in the liquid phase by the GC / MS method (gas chromatography / mass spectrometry) are listed below.
Specifically, Hensen, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, Trichloroethylene, tetrachloroethylene, 1,3-dichloropropene, toluene, xylene, chloroform, trans-1,2-dichloroethylene, 1,2-dichloropropane, p-dichlorobenzene, bromodichloromethane, dibromochloromethane, trichloromethane (chloroform) , Tribromomethane (bromoform), and the like.

Examples of VVOC include ethyl acetate, n-hexane, dichloromethane, pentane, acetaldehyde, methyl mercaptan, and the like.
Examples of SVOCs include tributyl phosphate, chloropyrifos, thiapentazole, dibutyl phthalate, dioctyl phthalate, PCB (polychlorinated biphenyl), and coplana-PCB.

Since VOC substances are generally highly volatile, their emissions at the source are mainly emitted into the atmosphere, and their behavior in the environment is mainly in the atmosphere.
However, contamination of the water environment and soil environment due to rain has become a problem.
In other words, since most of the VOC substances have a higher specific gravity than water, and have a lower viscosity and surface tension, if leaked into the soil, they are relatively difficult to adsorb on the soil, and if there are cracks, the concrete will also pass through. It may penetrate deep underground and diffuse in aquifers, causing widespread groundwater contamination.

The liquid VOC material is a mainly non-flammable liquid that is volatile at room temperature.
Conventionally, since many liquid VOC substances have high solubility, mainly for various cleaning agents, as raw materials, they are used as solvents for various chemical products, such as chemical industry, pharmaceuticals, electronic parts / equipment, metal parts / equipment, etc. To dry cleaning, it has been used in large quantities as a useful solvent in a very wide range of fields.
As harmfulness is regarded as a problem, regulations such as production, import and use of typical trichlorethylene, tetrachloroethylene, and carbon tetrachloride are imposed on VOC substances.
VOCs are not naturally derived, such as heavy metals, and are not substances that exist in nature, so they are caused by human causes, and therefore, even if they are below environmental standards, it is understood that they are not in a natural state. The
For this reason, there are many cases where the VOC substance is contained in the discharged water from the factory, and since it can be treated more easily than air, a method of treating it by dissolving or dispersing in water may be used.

Examples of the VOC material removal method and the detoxification method include a combustion decomposition method, an adsorption-type removal method, a catalytic combustion method, and a heat storage type decomposition method.
The combustion decomposition method is a method of decomposing a VOC material by heating at about 750 ° C., but the decomposition rate is high, but there are defects such as generation of SO _X , NO _{X and the} like when heavy oil fuel is used for combustion. is there.
The adsorption removal method is a method in which a VOC substance is adsorbed on an activated carbon layer and hot air is applied to the activated carbon layer, and the structure of the apparatus is simple, but there is a problem that periodic replacement and maintenance are required.
The catalytic combustion method is a method in which a VOC substance is applied to a catalyst heated to about 350 ° C., and has an advantage that it can be processed at a relatively low temperature. However, since the catalyst itself is poisoned, a problem of disposal arises. Therefore, there is a problem that NO _X occurs.
The thermal storage decomposition method is a decomposition method in which the room between the heat storage materials is burned and heated, and the VOC material is allowed to pass through the chamber, but the life of the heat storage material is semi-permanent, but SO _X , NO _X, etc. are generated. There is a defect.

As described above, the combustion decomposition method, the adsorption removal method, the catalytic combustion method, and the thermal storage decomposition method, which are currently used methods for removing VOC substances, have advantages, but there are also defects and problems. There are many current situations.
In addition, since the harmfulness of VOC substances has been regarded as a problem, the provision of more innovative methods and devices is desired.

In consideration of the above-described conventional problems, the present invention decomposes the VOC substance in a VOC substance aqueous solution and / or VOC substance dispersed water (hereinafter referred to as VOC substance-containing water) in which the VOC substance is present in water. The purpose is to provide technology.
That is, a method for decomposing a VOC substance that is highly degradable, has no side effects such as generation of harmful substances, and requires only a small amount of consumable material. And an apparatus.

As a result of intensive studies on a technique for decomposing a VOC substance in water containing a VOC substance using a laser, the inventors have reached the following invention.
That is, in the decomposition method using a laser, in the boiling point classification, VOC materials from VVOC having a low boiling point to SVOC having a high boiling point are irradiated with laser to water containing VOC material existing in water. Then, the invention is a method for detoxifying the VOC substance in the VOC substance-containing water.
As shown in FIG. 3, the half-value width of the oscillation pulse waveform is 1000 ps (picoseconds) to 50 fs (femtoseconds) from the outside of the glass tube part to the VOC substance-containing water 8 present in the transparent glass tube part 5. The ultrashort pulse laser-2 is condensed by the objective lens 3 to increase the density and irradiated so as to form the focal point 4 in a dotted or linear manner.
Contained in water, characterized in that the action of the ultra-short pulse laser causes the VOC substance-containing water present in the glass tube part to break and decompose and detoxify the molecular binding part of the VOC substance-containing water. Invented a method for decomposing a VOC material.

In the decomposition apparatus using a laser, in the boiling point section, VOC materials from VVOC having a low boiling point to SVOC having a high boiling point are irradiated to the VOC material-containing water existing in water. And it is invention of the apparatus which detoxifies the said VOC substance in the said VOC substance containing water.
As shown in FIG. 4, the apparatus comprises a circulation part for the VOC substance-containing water and a laser irradiation part 59 for the VOC substance-containing water, and the circulation part circulates the VOC substance-containing water. A transparent glass tube portion 48 is inserted and connected to the conduit portion, and the VOC substance-containing water that allows the glass tube portion to stay or pass through the passage portion. A circulation pump device 51, a switching plug 52 for selecting circulation or non-circulation, and a discharge conduit 57 are provided.
The pump device section and the switching plug section are provided with a control section for controlling the passage mode of the VOC substance-containing water in the glass tube, that is, the temporary residence, the temporary passage, or the multiple circulation passage.
The laser irradiator collects an ultrashort pulse laser 61 with a half-value width of 1000 ps to 50 fs of an oscillation pulse waveform from a laser oscillator from the outside of the glass tube portion by an objective lens 62. It is an apparatus that can increase the density and focus in the glass tube in the form of dots or lines.
In the glass tube portion inserted and connected to the conduit portion, the VOC material-containing water in the VOC material-containing water is cut, decomposed and rendered harmless, and discharged from the discharge conduit portion. It is invention of the decomposition | disassembly apparatus of the VOC substance contained in water characterized by these.

Further, in the method for decomposing a VOC substance in the VOC substance-containing water, a metal, or / and a metal compound, or / and a single semiconductor, or / and a semiconductor compound are added to the VOC substance-containing water.
By the method, the decomposition efficiency of the VOC substance in the VOC substance-containing water is increased by the action of the ultrashort pulse laser, and / or the by-product accompanying the decomposition is reduced, It is invention of the decomposition | disassembly method of the VOC substance contained in.

In addition, in the VOC substance-decomposing apparatus in the VOC substance-containing water, the VOC substance-containing water contains an additive, that is, a metal, or / and a metal compound, or / and a single semiconductor, or / and a semiconductor compound, the VOC substance-containing water. It is an apparatus that can be added according to the amount of water injected.
By using the apparatus, the additive is added, and the decomposition efficiency of the VOC substance in the VOC substance-containing water is increased by the action of the ultrashort pulse laser, and / or the by-products accompanying the decomposition are reduced. The invention is an apparatus for decomposing a VOC substance contained in water.

(1) Using a method of irradiating an ultrashort pulse laser, it is possible to completely break the molecular bond of the VOC substance, and by-products are completely generated by adding a small amount of an additive (catalyst, etc.). You can avoid it.
(2) It is a clean method in the VOC substance decomposition method and decomposition apparatus, and almost no consumable material is required, and is economical in terms of totality.
(3) VOC substances discharged from factories and the like are dissolved or / and dispersed in water to form VOC substance-containing water, and then concentrated to increase the concentration of VOC substances, and then the method and apparatus of the present invention are applied. As a method for treating a VOC material, the efficiency can be further improved.
(4) By adding a small amount of a fine powder such as a metal such as Au, a metal compound, a semiconductor simple substance, or a semiconductor compound to water containing the VOC substance, the VOC substance can be irradiated by irradiation with a lower energy laser. Can be disassembled.
(5) The method for decomposing a VOC substance of the present invention can be applied to the decomposition of many other harmful chemical substances, and greatly contributes to the improvement of environmental problems.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings based on examples.
FIG. 1 is a schematic diagram showing the concept of the present invention, and is a schematic diagram for irradiating water containing VOC material with an ultrashort pulse laser.
In FIG. 1, the VOC substance-containing water 8 flowing in from the direction of the arrow 7 passes through the transparent glass tube portion 5 from the conduit portion 6 or temporarily stays, reaches the conduit portion 9, and flows out in the direction of the arrow 10.
On the other hand, the ultrashort pulse laser-2 irradiated from the laser oscillator 1 is condensed by the objective lens 3 and forms a focal point (condensing point) 4 at the center of the glass tube portion 5.
Therefore, the VOC substance existing in the VOC substance-containing water 8 in the glass tube is decomposed into harmless water under the action of the ultrashort pulse laser 11 having a very high power density.
Note that the objective lens 3 may be a cylindrical lens and may be linearly assembled at the center of the cross section of the glass tube portion 5 (in the direction perpendicular to the paper surface in the drawing).

Laser oscillation includes CW oscillation (continuous oscillation) and pulse oscillation. In CW oscillation, oscillation is continuously continued when it is electrically on, and pulse oscillation is an oscillation in which on and off are repeated. It is.
The pulse width in the case of pulse oscillation is indicated by a half width of the pulse (also referred to as full width at half maximum; also referred to as a full width at half maximum), and is a pulse width (time) of a half of the pulse power-peak value.
In the case of pulse oscillation, the off-time power is concentrated into the on-time pulse, so that instantaneous high power can be obtained.
Therefore, the width of one pulse indicated by the half width is an important factor.
For this reason, the power of laser oscillation is generally indicated by the amount of work J (journal) per second, that is, the work rate W (watts) in the case of the CW transmission. The case is indicated by the work amount J per pulse.

Among the pulse oscillation lasers, the ultrashort pulse laser has an extremely short pulse half-width, and an extremely high power laser works before the laser reaches the irradiated part. To the department.
When the inventor irradiates a VOC substance containing ultra-short pulse laser in water, the specific binding part of the molecule of the VOC substance is cut and the VOC substance is decomposed in a very short time. It was something that was found.
That is, before the heat reaches the irradiated portion, a specific bonding portion of each VOC substance molecule is cut and broken by an ablation effect (a destruction process not accompanied by heat) to render it harmless.
Therefore, since the ultrashort pulse laser with the pulse width ps order or the pulse width fs order has an action of cutting the interatomic or intermolecular bond, it can be said that the name of the molecular knife applies. .

The inventor examined the range of ultrashort pulse lasers that have the effect of decomposing specific bonds in the molecules of VOC materials, and as a result of experiments and logical considerations, the boundary was not clear, but the pulse width Was found to be in the range of approximately 1000 ps to 20 fs.
That is, it has been found that when the boundary exists in the vicinity of about 1000 ps and the pulse width is shorter than about 1000 ps, the molecular bond portion can be destroyed by the ablation effect.
Although the power density is higher when the pulse half-width of the ultrashort pulse laser is shorter, ultrashort pulse oscillators with a half-width of up to about 20 fs have been made for experiments and research. From the fact that an ultrashort pulse laser oscillator of 50 fs or less has not been practically used yet, it is considered that the range of 1000 ps to 50 fs is appropriate from the practical viewpoint.

As an ultrashort pulse laser of the order of ps, a dye laser having a wavelength of 320 to 1260 nm (nanometer) in which the laser medium is liquid and a dye and an organic solvent are used, and the wavelength is near red. For example, Nd: YVO _{4 having} a thickness of 1064 nm, YAG modelock laser, and the like can be given.
As an ultrashort pulse laser of fs order, there is a titanium sapphire laser (TiAl ₂ O ₃ laser in which titanium Ti is doped on a base material sapphire).
A titanium sapphire laser uses a wavelength selection element in addition to a laser mirror, and can be driven by a controller or an external signal to automatically select a wavelength. Wavelength lasers can be output.

FIG. 2 is a conceptual diagram showing a pulse waveform and a pulse width (time) of an ultrashort pulse laser.
FIG. 2 is a conceptual drawing of a pulse waveform 28 with time t on the horizontal axis and laser power (energy) P on the vertical axis.
Moment oscillated Les - The - in the pulse waveform 28, the pulse width w as described above is generally - The - the peak - p _h is 1/2 of locations (peak click intensity) p _m It is indicated by the half-value width w in the part.
Since the power at the time of OFF of the repetition frequency of the pulse oscillation excitation is integrated into one pulse of the ultrashort pulse laser, the power per one pulse becomes very high.

In an ultra short pulse laser of fs order, for example, the power density at a wavelength of 800 nm in the near infrared region by a titanium sapphire laser is obtained when the light is condensed by an objective lens when the pulse width is 100 fs. It is extremely high power of about 10 ¹³ W / cm ² .
For example, the bond energy of O—H is 463.0 kJ / mol, that of carbon single bond C—C is 347.9 kJ / mol, and that of C—H is 98.8 kJ / mol. The power is very high compared to the binding energy.

As shown in FIG. 1, when a VOC substance-containing water VOC substance existing in a transparent glass tube part 5 is irradiated with a high power density ultrashort pulse laser, a specific molecular bond part is formed. Examples of VOC materials that have been confirmed to be destroyed are shown below.
Examples of VOC include 1,1-dichloroethylene, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, and trichloroethylene.
Examples of VVOC include acetaldehyde and methyl mercaptan.
SVOC includes chloropyrifos, dibutyl phthalate, PCB, coplanar-PCB, and the like.

Furthermore, the inventor added a single metal such as Au or Pt, a single semiconductor such as Si or Ge, or a semiconductor compound such as FeSi ₂ CdS, ZnS, GaAs, InSb, SiC, or ZnO as an additive to the VOC substance-containing water. It was suggested that by adding a trace amount, the VOC substance can be decomposed by irradiation with a laser having a lower power.
A laser reacts with a metal, a metal compound, or a semiconductor, and emits soft X-rays in the case of a metal, or emits an electromagnetic wave in the order of TH _Z (terahertz; 10 ¹² hertz) in the case of a semiconductor. There is a phenomenon such as emission, and it is considered that the electromagnetic wave having such a wavelength affects the VOC material and the action of the laser is strengthened.

FIG. 3 is a conceptual schematic diagram of an area covered by power in the glass tube portion 5 where the laser is focused.
In the transparent glass tube portion 5 in FIG. 1, the parallel laser-2 irradiated from the ultrashort pulse laser oscillator 1 connects the focal point 4 to the central portion in the glass tube portion by the objective lens 3. It shows that.
FIG. 3 is an enlarged conceptual schematic diagram of a portion of the glass tube portion 5 shown in FIG. 1, and shows a state in which the irradiation laser 2 forms a focal point 4 at the center of the glass tube portion 5 by the objective lens 3. Show.
In FIG. 3, the VOC substance-containing water 8 passes or temporarily stays in the glass tube part 5 from the direction of the arrow 7 and flows in the direction of the arrow 10, but the region where the power of the laser is the strongest. Is a small broken line enclosing portion 33 centering on the focal point 4 of the laser-11.
The inventor has found that the laser power decreases as the distance from the focal point 4 decreases, but in the case of the destruction of the joint of the VOC material, as shown by the dashed box 34, it has a wide range. Is.

  Further, if the objective lens 3 depicted in FIG. 3 is changed from a convex lens shape to a cylindrical objective lens, the laser-2 is assembled linearly at the center in the cross-sectional direction of the glass tube portion 5, It has been found that the laser which acts on a wide area can be irradiated with the VOC substance-containing water 8.

In the case of a transparent glass tube having an inner diameter of about 10 mm (millimeter), the region indicated by the broken-line box 34 centered on the focal point 4 of the laser 11 covers the entire inner diameter of the glass tube in the cross-sectional direction. In the longitudinal direction, it was found that the focal length reached several millimeters.
Further, if the objective lens 3 is a cylindrical objective lens and the lasers 2 are assembled linearly, the entire inner diameter of the glass tube can be applied uniformly, and the VOC substance-containing water 8 can be efficiently used. It was also found that the laser can be irradiated.
When the ultrashort pulse laser is used for fine hole processing or fine groove processing in metal or synthetic resin, this sharp focal point is used. The VOC which is the object of the present invention is used. In the case of the breakage of the VOC substance molecule bond in the substance-containing water, it has been found that the bond of the VOC substance molecule is broken in a considerably wide area.

FIG. 4 is a schematic diagram of an example of a VOC material decomposition apparatus in water containing VOC material held in a tank.
FIG. 4 shows an example of an apparatus for injecting VOC substance-containing water from the direction of the arrow 44 through the conduit portion 45 and decomposing VOC in the VOC substance-containing water 41 held in the tank 40.
FIG. 4 shows an example of an apparatus that can adopt either a circulation pass process or a single pass process when the VOC substance-containing water 41 is passed through the glass tube portion 48 on which the ultrashort pulse laser 61 acts. It is.
Further, the apparatus is used in the case where an additive such as a metal, or / and a metal compound, or / and a single semiconductor, or / and a semiconductor compound is added as an additive to the VOC substance-containing water. 63 is provided upstream of the infusion conduit 45.
The additive adder is a device that injects the predetermined additive in a predetermined addition amount in accordance with the flow rate of the VOC substance-containing water 41 injected into the tank 40 from the conduit portion 45.
In order to prevent unevenness and precipitation of the injected additive, the VOC substance-containing water is stirred by the stirring propeller 42 in the VOC substance-containing water tank 40.

Explaining the case of the circulation passing process, in FIG. 4, the VOC substance-containing water 41 in the tank flows in the direction of the arrow 47 through the conduit portion 46 by the pump 51, and the laser in the broken line enclosing portion 59. It passes through the transparent glass tube 48 of the processing unit.
After receiving the action of the laser in the glass tube part 48, it flows in the direction of the arrow 50 in the conduit part 49, and the flow path to the conduit part 53 is opened by the switching plug 52 via the pump part 51, Since the flow path to the part 57 is closed, it flows in the direction of the arrows 55 and 56 via the conduit parts 53 and 54 and returns to the inside of the tank 40 to circulate.

In the laser processing unit 59 indicated by the broken line encircled portion in FIG. 4, the ultrashort pulse laser 61 from the laser oscillator 60 is condensed by the objective lens 62 and the cross section in the glass tube portion 48 is obtained. The focus is on the center of the direction.
In this part, an area covered by the laser power indicated by a broken line encircled portion 34 as shown in FIG. 3 is formed.
While the VOC substance-containing water is temporarily staying in or passing through the glass tube part 48, the VOC substance molecule binding part is broken by the action of an ultrashort pulse laser.
In the case of the circulation passing treatment, this circulation is repeated, and when the amount of the VOC substance in the VOC substance-containing water reaches a harmless area, the flow path to the conduit part 57 is opened by the switching plug 51, and the conduit part 53 The flow path to is closed and discharged as harmless water in the direction of the arrow 58 from the conduit portion 57.

In the case of the single-pass treatment, the VOC substance-containing water 41 is caused to flow in the direction of arrow 47 via the conduit portion 46 by the pump 51, through the glass tube portion 48 of the laser treatment device portion 59, Under the action of the ultrashort pulse laser, it flows in the direction of arrow 50 via the conduit 49 and the pump 51.
The switching plug 52 opens the flow path to the conduit section 57, closes the flow path to the conduit section 53, and is discharged from the conduit section 57 as harmless water in the direction of the arrow 58.
Thus, in the case of the single-pass treatment, the VOC substance-containing water is temporarily retained or passed through the glass tube portion 48 once, and the bonded portion of the VOC molecules in the VOC aqueous solution is destroyed, resulting in harmless water. Discharged.

Whether to use the circulating or single-pass treatment is determined by the contents of the VOC substance-containing water such as the type and content of the VOC substance contained in the VOC substance-containing water, the type of ultrashort pulse laser, the power -Or the presence or absence of an additive such as a catalyst.
Note that the VOC material decomposition apparatus for water containing VOC material as shown in FIG. 4 is an effective device when applied to waste water containing VOC material from a factory using a liquid VOC material as a solvent.
That is, the VOC substance contained in the exhaust gas is dissolved or dispersed in water, and in some cases, the VOC substance in the VOC substance-containing water is concentrated together with the waste water containing the VOC substance from other systems, and the VOC substance as shown in FIG. If the harmless treatment is performed with the VOC substance decomposition apparatus in the contained water, the VOC substance can be treated efficiently.

According to the method or apparatus of the present invention, it is possible to completely break the molecular bond of the VOC substance using the laser.
Further, by adding a small amount of an appropriate additive (such as a catalyst), the decomposition efficiency of the VOC substance can be increased, and / or no by-product can be generated at all. This is a clean method and has the advantage that almost no consumable material is required.

FIG. 5 shows a schematic diagram of an apparatus for decomposing VOC material in water used in this example.
In FIG. 5, the VOC substance in the VOC substance-containing water 68 to be decomposed is put in a transparent glass tubular bottle 69 and set in a part of the underwater VOC substance decomposition apparatus.
5, Les - The - oscillator 72 is - The - pulse rates using titanium sapphire as a medium - The - an oscillator, oscillating fs pulse rates - The - center wavelength of 780 nm, repetition frequency 1 kH _Z, pulse The width was 217 fs.
The laser 73 from the laser oscillator 72 is irradiated in the direction of the arrow, the direction is changed by the dichroic mirror 74, and the light is condensed by the objective lens 77 via the filter 75 and the electromagnetic shutter 76. The focal point 4 is arranged at the center of the glass tubular bottle 69 in which the VOC substance-containing water 68 is placed.

The transparent glass tubular bottle 69 is a circular tube having an inner diameter of 1 cm and a length of 3 cm.
The VOC substance and concentration in the VOC substance-containing water 68 are selected from the VOC group that can be analyzed by the GC / MS method, and 1,1-dichloroethylene is 0.2 mg / L (liter), trans-1,2 -VOC substance containing water of 10 mg / L for dichloroethylene, 100 mg / L for cis-1,2-dichloroethylene, and 400 mg / L for trichlorethylene.

The pulse laser oscillator 72 was operated, and each of the four kinds of VOC substance-containing water in the transparent glass tube bottle 69 was irradiated with the fs pulse laser.
The power per pulse was adjusted by the filter to be two levels of 20 μJ (microjoule) and 100 μJ.
The irradiation time of the fs pulse laser was 30 minutes.

The analysis of the unradiated sample and the obtained fs pulse laser irradiated sample was analyzed by the GC / MS method.
Thus, the results shown in Table 1 were obtained.

According to Table 1, in the case of 1,1-dichloroethylene which is a VOC substance, the non-radiated sample of the ultrashort pulse laser light is 0.2 mg / L, whereas the irradiation power is 20 μJ (per pulse). Under the (power value), the sample was reduced to 0.14 mg / L in the sample without additives (catalyst, etc.), and the result was ND (below the lower limit of detection) in the sample with a small amount of Au (gold) powder added Met.
With respect to the same VOC material as described above, under the irradiation power of 100 μJ, both the sample with no additive and the sample to which a small amount of Au powder was added as an additive were ND.

In the case of trans-1,2-dichloroethylene, which is a VOC material, the non-radiated sample is 10 mg / L, the irradiation power is 20 μJ, and 100 μJ. It was ND.
In the case of cis-1,2-dichloroethylene as a VOC substance, the non-radiated sample is 100 mg / L, the irradiation power is 20 μJ and 100 μJ, the additive-free sample, and the Au-added sample. Both were ND.
Further, in the case of trichlorethylene of the VOC material, the non-radiated sample was 400 mg / L, and the additive-free sample and the Au-added sample were ND under the radiation power of 20 μJ and 100 μJ.

In summary, in the case of 1,1-dichloroethylene, under the laser irradiation power of 20 μJ, the sample without a small amount of Au was only reduced by almost half. Under the irradiation power of 100 μJ, the result was ND regardless of whether or not a small amount of Au was added.
Therefore, it was found that the addition of a small amount of Au increases the irradiation effect of the laser, that is, the decomposition power of the VOC substance.
In addition, in the case of trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, and trichloroethylene, the emission power is 20 μJ and 100 μJ, and it is ND regardless of whether or not a small amount of Au is added. Of VOC material was completely decomposed.

In the same fs pulse laser as in Example 1, compared with the case of Example 1, the case of lower power, the case of shorter irradiation time, and Example 1 added to water containing VOC substance And other effects of the additive were studied.
In the VOC substance-containing water, the same sample as in Example 1 was used, and the same VOC substance-containing water decomposition apparatus as in Example 1 was used.
As in Example 1, the selected VOC materials were 1,1-dichloroethylene, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, and trichloroethylene. And the same.
As the additive, a small amount of sintered composite ore powder obtained by sintering silicon, iron or the like at a high temperature under vacuum was added.
In addition, since the main component of the sintered composite ore is FeSi ₂ , this is used for the indication of the additive.
The power per pulse of the fs pulse generator was adjusted by the filter to 1, 10, and 20 μJ, and the irradiation time was 1 minute and 30 minutes.

The analysis of the unirradiated sample and the obtained ultrashort pulse laser-irradiated sample was performed by the GC / MS method as in Example 1.
Thus, the results shown in Table 2 were obtained.

According to Table 2, in the case of 1,1-dichloroethylene, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, and trichloroethylene, none was detected from the sample after laser light irradiation. It was ND.
Even when the pulse power was 1 μJ, it was shown that these VOC materials were completely decomposed regardless of the presence or absence of the additive FeSi ₂ .

In addition, the contribution of the additive to the degradability of the VOC substance was unknown because it was not performed for irradiation power of less than 1 μJ, but as an additive effect of the additive, an effect that no by-product was generated at all. It was observed.
That is, since trace amounts of acetone, acetic acid, and propionic acid were detected from the sample without addition of the additive, but were not detected at all from the sample with addition of the additive. The result was considered to be an effect.

It is possible to completely break the molecular bond of the VOC substance using an ultrashort pulse laser, and no by-product is generated if the conditions are adjusted.
Therefore, two methods such as SO _X NO _X , such as those associated with the conventional methods of removing VOC substances, the decomposing method such as the combustion decomposition method, the adsorption type removal method, the catalytic combustion method, or the thermal storage type decomposition method, are used. There is no side effect that the next harmful substance is generated or the catalyst is poisoned.
Further, the present invention is a clean method in the method of decomposing the VOC material, and is considered to be economical from the perspective of the future as a future direction.

In particular, it is an industrially suitable method to contain VOC discharged from a factory using a liquid VOC substance in water and concentrate it to increase the VOC concentration and apply the present invention.
In addition, by adding a small amount of Au powder or the like as an additive to VOC substance-containing water, the VOC substance can be decomposed by irradiation with a lower energy laser. In this method, no by-product is generated.
Therefore, the search for more effective catalysts and the like suggested the possibility of providing a technology for decomposing more efficient and more economical VOC materials.
In addition, the VOC material decomposition method and apparatus of the present invention can be applied to the decomposition of other harmful chemical substances, and greatly contributes to the improvement of environmental problems.
Therefore, the industrial applicability is extremely wide and contributes to the industry.

Conceptual diagram of irradiating laser to water containing VOC substance Schematic diagram showing pulse waveform and width of ultra-short pulse laser Conceptual diagram of the range of power in the glass tube where the laser is focused Schematic of VOC substance decomposition equipment in water containing VOC substance reserved in tank Schematic of VOC substance decomposition equipment for water containing VOC substance by femtosecond pulse laser

Explanation of symbols

1 Laser oscillator 2 Ultra-short pulse laser
3 Objective lens 4 Laser focus (focusing point)
5 Transparent glass tube part 6 Conduit part 8 VOC substance-containing water 9 Conduit part 28 Pulse waveform 33 Small broken line encircled area; area covered by strong laser power 34 Broken line encircled area; covered by laser power Area 40 VOC substance-containing water tank 41 VOC substance-containing water 42 Stirring propeller 45 Injection conduit section 46, 49 In-apparatus conduit section 48 Transparent glass tube section 51 Pump 52 Switching plug 53, 54 Circulation conduit section 55, 56 Arrows; Flow direction 57 in the case of circulation Discharge conduit part 58 Arrow; Discharge direction 59 Broken line enclosing part; Laser processing unit 60 Laser oscillator 61 Ultrashort pulse laser
62 Objective Lens 63 Additive Adder 68 VOC-Containing Water 69 Tubular Glass Bottle 72 Pulse Laser Oscillator 73 Femtosecond Pulse Laser Light 74 Dichroic Mirror
75 Filter
76 Electromagnetic shutter
77 Objective Lens t Time P Power (Energy)
p _m power - the peak p _h peak half-value position w pulse half width (time)

Claims (4)

In the method for decomposing a VOC substance contained in water,
In the boiling point classification, a VOC substance containing water in which VOC substances ranging from a low boiling point VVOC to a high boiling point SVOC are present in water is irradiated with a laser to detoxify the VOC substance in the VOC substance containing water. A way to
An ultrashort pulse laser with a half-value width of the oscillation pulse waveform of 1000 ps to 50 fs is condensed from the outside of the transparent glass tube part to the water containing the VOC substance existing in the transparent glass tube part by an objective lens. By increasing the power density and irradiating so as to focus in a spot or line,
By the action of the ultra-short pulse laser, the VOC substance-containing water present in the glass tube part is cut and decomposed to detoxify the molecule-bonded part of the VOC substance-containing water,
A method for decomposing a VOC substance contained in water. In a decomposition apparatus for VOC substances contained in water,
In the boiling point classification, VOC materials from VVOC having a low boiling point to SVOC having a high boiling point are irradiated with laser to water containing VOC material existing in water, and the VOC material in water containing the VOC material is harmless. A device that
The apparatus comprises a circulation part of the VOC substance-containing water and a laser irradiation part to the VOC substance-containing water,
The flow part has a conduit part through which the VOC substance-containing water flows, and the transparent glass tube part is inserted and connected to the conduit part.
The passage pipe portion includes a pump device portion for circulating the VOC substance-containing water that allows the glass tube portion to stay or pass through, a switching plug portion that selects circulation or non-circulation, and a discharge conduit portion.
The pump device unit and the switching plug unit include a control unit for controlling the passage mode of the VOC substance-containing water in the glass tube, that is, temporary residence, temporary passage, or multiple circulation passes, and the like.
The laser irradiating unit collects an ultrashort pulse laser with a half-value width of 1000 ps to 50 fs of an oscillation pulse waveform from a laser oscillator from the outside of the glass tube unit with an objective lens. While increasing the condensing density, the glass tube can be focused in the form of dots or lines,
In the glass tube portion inserted and connected to the conduit portion, the VOC material molecule water in the VOC material-containing water is cut, decomposed and rendered harmless, and discharged from the discharge conduit portion. Characterized by
An apparatus for decomposing VOC substances contained in water. In the method for decomposing a VOC substance contained in water,
By adding an additive, that is, a metal, or / and a metal compound, or / and a single semiconductor, or / and a semiconductor compound to the water containing the VOC material,
2. The decomposition efficiency of the VOC substance in the VOC substance-containing water by the action of the ultrashort pulse laser is increased, and / or a by-product accompanying the decomposition is reduced. A method for decomposing a VOC substance contained in water. In a decomposition apparatus for VOC substances contained in water,
An additive adder for adding an additive, that is, a metal, or / and a metal compound, or / and a single semiconductor, or / and a semiconductor compound to the VOC substance-containing water according to an injection amount of the VOC substance-containing water; Equipped,
The addition of the additive by using the additive adder increases the decomposition efficiency of the VOC substance in the VOC substance-containing water by the action of the ultrashort pulse laser, and / or a by-product accompanying the decomposition. It is possible to reduce
The decomposition | disassembly apparatus of the VOC substance contained in the water of Claim 2.

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