JP2007105060A - Method of decomposing dioxins in liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of decomposing dioxins in liquid, capable of decomposing dioxins in liquid under a mild condition with lower reaction requiring energy and at a high decomposing rate without requiring an exclusive container. <P>SOLUTION: The method is for decomposing dioxins included in a liquid filling or stored in a container and is characterized by the decomposition of dioxins in liquid by preparing a mixture liquid by adding a hydrogen donor and an alkaline compound to a treated liquid including the dioxins, taking out part of the mixture liquid after that, applying microwaves to the taken-out mixture liquid while letting the mixture liquid flow into a catalyst filled device set inside a microwave device, and after that, returning the mixture liquid into the container. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for decomposing a dioxin in a liquid, and more particularly, to a method for decomposing a dioxin in a liquid capable of detoxifying dioxins in a liquid at a high decomposition rate under mild conditions.

  Dioxin (polychlorodibenzodioxin: PCDD), polychlorodibenzofuran (PCDF), and coplanar PCB (in the present invention, these three are collectively referred to as “dioxins”) are a process of burning chlorine-containing organic compounds or It is produced as a by-product in the synthesis process of specific organic compounds containing chlorine. Dioxins have been regarded as a problem in recent years as one of the pollutants of the environment (air, soil, water, etc.) due to their strong toxicity.

  For this reason, as a measure against environmental pollution, processing for removing and collecting soil, combustion ash, etc. contaminated with dioxins is performed. In addition, dioxins contained in wastewater from various factories such as cleaning factories, leachate generated at waste landfill sites, and washing wastewater such as ash and soil are also being treated. As a countermeasure, it is necessary to decompose dioxins in polluted substances.

  Dioxins require a high temperature of 80 to 900 ° C. or higher for thermal decomposition, are thermally stable compounds, and are chemically stable compounds. For this reason, various decomposition methods have been studied in the past, but all require special reaction conditions or special chemicals.

  For example, Patent Document 1 discloses dioxins composed of specific nitrogen-containing sulfur-containing compounds (such as Na salt of trimercaptotriazine) as a method for decomposing fly ash discharged from an incinerator and dioxins contained in the incineration ash. There has been proposed a method in which a decomposing agent and dioxins are contacted at 200 ° C. to 300 ° C. for 3 to 60 minutes. However, this method is an excellent method in that dioxins can be decomposed by contacting them at a temperature lower than 300 ° C, but the decomposition rate of dioxins is low, and a high temperature treatment of 200 ° C or higher is required. Therefore, it is difficult to say that it is a mild decomposition treatment method.

  Patent Document 2 proposes a honeycomb-type cracking catalyst in which vanadium pentoxide and tungsten trioxide are supported on titanium oxide as a cracking catalyst for coplanar PCBs contained in exhaust gas from garbage incineration facilities and sludge incineration facilities. Has been. However, this catalyst is applied to the decomposition of dioxins in exhaust gas, and the required decomposition temperature is as high as 200 ° C.

  Patent Document 3 proposes a catalyst in which a noble metal such as platinum is supported on cerium oxide-zirconium oxide in which oxygen defects are introduced by reduction treatment. This catalyst has a contact temperature of 0 to 100 ° C. between the catalyst and the material to be treated, and is a catalyst capable of detoxifying dioxins efficiently at a sufficiently low treatment temperature. The toxicity equivalent of dioxins is as high as 0.097 (ng-TEQ / g).

  By the way, the decomposition catalysts proposed in the above Patent Documents 1 to 3 are mainly suitable for the treatment of incineration ash. There is a method of removing dioxins from the liquid by adsorbing the dioxins to the adsorbent as a treatment method for dioxins in the liquid, but this method generates an adsorbent (secondary waste) that adsorbs dioxins. That process is required. Conventionally, combustion at high temperature has been adopted, but with this method, dioxins may be generated in the gas if proper temperature control is not performed, and a large amount is required for high temperature combustion. Fuel is required and the energy cost increases.

  Therefore, Patent Document 4 proposes a method capable of treating dioxins in liquid without generating secondary waste. However, in one of a plurality of processing steps, it is necessary to keep the slurry containing the adsorbent adsorbed with dioxins at a temperature that is 100 ° C. or higher and maintains the liquid phase, and the processing step is also complicated. Therefore, it is difficult to say that it is a low energy cost processing method.

JP 2001-247838 A JP 2002-136873 A JP 2002-306965 A JP 2001-321785 A

  The present invention has been made in view of the above-described conventional problems, and does not require a dedicated reaction tank, has low energy required for decomposition, is mild in conditions, and detoxifies dioxins in liquid at a high decomposition rate. It is an object of the present invention to provide a method for decomposing dioxins in liquid.

  As a result of intensive studies to solve the above problems, the present inventors prepared a liquid mixture by adding a hydrogen donor and an alkali compound to a container containing a liquid to be treated containing dioxins in the liquid. The present invention found that dioxins in a liquid can be rendered harmless by decomposing dioxins by irradiating them with microwaves while circulating them through a catalyst filling device installed in a microwave device, and returning them to the container. Reached.

That is, the present invention is as follows.
1) A decomposition method for decomposing dioxins contained in a liquid filled or stored in a container, wherein a mixed liquid is prepared by adding a hydrogen donor and an alkali compound to the liquid to be treated containing the dioxins. Then, take out a part of the mixed solution, irradiate it with microwave while circulating it through the catalyst filling device installed in the microwave device, and then return it into the container to decompose the dioxins in the solution A method for decomposing dioxins in liquid, characterized by:
2) The liquid according to 1), wherein the hydrogen donor is at least one compound selected from the group consisting of a heterocyclic compound, an amine compound, an alcohol compound, a ketone compound, and an alicyclic compound. Dioxin decomposition method,
3) The method for decomposing dioxins in liquid according to 1), wherein the hydrogen donor is an alcohol compound having a boiling point of 100 ° C. or lower,
4) The decomposition treatment of dioxins in the liquid according to any one of 1) to 3), wherein the amount of the hydrogen donor added is 5 to 50% (vol) as a ratio to the liquid to be treated containing dioxins. Method,
5) The submerged dioxins according to any one of 1) to 4), wherein the alkali compound is at least one compound selected from the group consisting of caustic soda, caustic potash, sodium alkoxide, potassium alkoxide, and calcium hydroxide. Decomposition method,
6) The hydrogen donor and alkali compound to be added to the liquid to be treated are alkali solutions having a concentration of 0.1 to 40% (w / v) obtained by dissolving an alkali compound in the hydrogen donor. ) A method for decomposing dioxins in a liquid according to any one of
7) The method for decomposing dioxins in liquid according to any one of 1) to 6), wherein the catalyst is at least one catalyst selected from a carbon crystal compound and a compound having a metal supported on a carrier. ,
8) The method for decomposing dioxins in liquid as described in 7) above, wherein the compound having a metal supported on the carrier is a palladium-supported carbon compound,
9) The method for decomposing dioxins in liquid according to any one of 1) to 8), wherein the dioxins are polychlorodibenzofuran (PCDF) and / or polychlorodibenzodioxin (PCDD), and
10) The method for decomposing dioxins in liquid according to any one of 1) to 9), wherein the liquid to be treated is drainage, leachate, contaminated water, contaminated oil, waste lubricating oil, or waste insulating oil.

  According to the present invention, a hydrogen donor and an alkali compound are added to a container containing a liquid to be treated containing dioxins in the liquid, and the resulting mixed liquid is circulated through a catalyst filling apparatus installed in the microwave apparatus. After irradiating with microwaves, it is returned to the container, so that the dioxins in the liquid can be easily decomposed at a high decomposition rate. Moreover, dioxins can be decomposed under mild conditions without the need for dedicated reactors or high-temperature / high-pressure reaction vessels, and without supplying hydrogen and heat from the outside, so that the energy required for decomposition can be reduced, The possibility of forming side reaction products is extremely low.

  In addition, by applying the method of the present invention to the decomposition of dioxins in waste insulating oil mixed with a small amount of polychlorinated biphenyl (PCB), PCB can be decomposed at a high decomposition rate and in the coexisting liquid. Dioxins, especially polychlorodibenzofuran (PCDF) and polychlorodibenzodioxin (PCDD) can be rendered harmless at a high decomposition rate.

  The method for decomposing dioxins in a liquid according to the present invention is a decomposition method for decomposing dioxins contained in a liquid filled or stored in a container, wherein the liquid to be treated containing the dioxins is a hydrogen donor. And an alkali compound are added to prepare a mixed solution, and then a part of the mixed solution is taken out and irradiated with microwaves while being circulated through a catalyst filling device installed in the microwave device, and then into the container. By returning, the dioxins in the liquid are decomposed.

  Examples of the container include storage / storage tanks for drainage / leachate, etc., column transformers containing a small amount of PCB, large transformers, equipment containers incorporating contaminated oil such as OF cable oil tanks, and the like.

  Examples of liquids containing dioxins in the liquid include incinerated ash, various types of cleaning wastewater from which soil has been washed, leachate from land and landfill sites, various contaminated water such as PCB-containing water, and PCB-containing oil And various other contaminated oils and waste oils. Examples of the waste oil include electrical insulating oil, heat medium oil, lubricating oil, and mineral oil extracted from an organic halogen compound contained in a solid.

  Examples of the hydrogen donor used in the present invention include organic hydrogen donors such as heterocyclic compounds, amine compounds, alcohol compounds, ketone compounds, and alicyclic compounds. Among these compounds, alcohol compounds, ketone compounds, and alicyclic compounds are preferable from the viewpoint of safety. In particular, they are highly safe, can be obtained at low cost, are easily controlled in reaction, and are aromatic. Alcohol compounds are preferred from the viewpoint of high decomposition efficiency of the group halogen compounds. These hydrogen donors can be used alone or in any combination of two or more. Here, the “hydrogen donor” means a compound that can donate a hydrogen atom to a radical generated from a decomposition target compound.

  The alcohol compound may be either an aliphatic alcohol or an aromatic alcohol, and a monohydric alcohol or a polyhydric alcohol having a linear or branched chain can be used. The carbon number of the alcohol compound is preferably in the range of 1 to 12, more preferably in the range of 2 to 9, and still more preferably in the range of 3 to 6. Specific examples of the alcohol compound include, for example, methanol, ethanol, 1-propanol, 2-propanol, n-butanol, s-butanol, t-butanol, 1-pentanol, 2-pentanol, and 3-pentanol. 1-hexanol, 2-hexanol, 3-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-octanol and other aliphatic alcohols, cyclopropyl alcohol, cyclobutyl alcohol, cyclopentyl alcohol, cyclohexyl Examples thereof include alicyclic alcohols such as alcohol, cycloheptyl alcohol and cyclooctyl alcohol, and polyhydric alcohols such as ethylene glycol, propylene glycol and decalin diol.

  Among alcohol compounds, alcohols having a boiling point of 100 ° C. or less are preferable, and examples thereof include methanol, ethanol, 1-propanol, 2-propanol, t-butanol and the like. These alcohol compounds are preferable because they are highly safe, can be obtained at low cost, can be easily controlled, and have high decomposition efficiency of dioxins. In addition, the use of alcohol having a relatively low boiling point is advantageous in that the decomposition efficiency can be increased while maintaining the reaction temperature low, and the production of side reaction products can be suppressed.

  Moreover, it is preferable from a viewpoint of handleability to select the said alcohol whose boiling point is higher than the reaction temperature mentioned later.

  The hydrogen donor is preferably used in an amount of 5 to 50% (vol), more preferably 10 to 40% (vol), relative to the liquid to be treated. When the amount of the hydrogen donor is less than 5%, the viscosity of the solution increases and the decomposition reaction does not proceed. On the other hand, when the amount of the hydrogen donor exceeds 50%, the reaction proceeds sufficiently, but there is no practical meaning and the container may exceed the allowable amount.

  The alkali compound used in the present invention can be used without limitation as long as it can promote the decomposition reaction of dioxins, but from the viewpoint of increasing the dechlorination efficiency, NaOH, KOH, sodium alkoxide, potassium alkoxide, Calcium hydroxide or the like is preferably used. Among these, NaOH or KOH is particularly preferable from the viewpoints of cost and handling properties. An alkali compound can be used individually or in combination of 2 or more types.

  The ratio of the alkali compound to the hydrogen donor is preferably 0.1 to 40% (w / v), more preferably 0.2 to 20% (w / v). If the ratio is less than 0.1%, the decomposition reaction does not proceed. If it exceeds 40%, the alkali compound cannot be completely dissolved. The alkali compound is preferably used in an amount of 0.02 to 10% (w / v) based on the liquid to be treated.

  The catalyst used in the present invention is at least one selected from a carbon crystal compound and a compound having a metal supported on a carrier, and can be used without limitation as long as it can promote the decomposition reaction of dioxins. The type is not particularly limited. An inorganic catalyst is preferable to an organic catalyst because it has a long catalyst life and is stable even in the presence of an alkali compound. The catalyst can be suitably used because it is considered to be highly safe in an alkaline atmosphere and exhibit high activity against microwaves, and a compound in which a metal is supported on a carrier is particularly preferable. Examples of the carrier include carbon such as activated carbon and graphite, metal oxides such as silica gel, alumina and zeolite, and composite metal oxides, resins such as polyethylene, polystyrene, polycarbonate, and polymethyl methacrylate. These catalysts can be used individually or in combination of 2 or more types.

  Here, examples of the carbon crystal compound include graphite, carbon nanotubes (both including and not including metal), fullerene, and the like.

The metal-supported oxide and metal-supported composite oxide can be used without limitation as long as they are metal-supported oxides and composite oxides. It is the same as the carbon compound. Specific examples of the metal-supported oxide include Pd / TiO ₂ (palladium-supported titanium dioxide). Specific examples of the metal-supported composite oxide include Pd / SiO ₂ .Al ₂ O ₃ (palladium-supported silica-alumina).

  Among the above catalysts, a metal-supported carbon compound in which a metal is supported on a carbon support is most preferred from the viewpoints of high microwave absorption, good decomposition efficiency, and high safety in an alkaline atmosphere.

  As said metal carrying | support carbon compound, if it is a carbon compound which carry | supported the metal, it can be used without a restriction | limiting, The metal carrying amount is 1-20 mass% with respect to the catalyst whole quantity, More preferably, it is 5-10 mass%. It is good to be. Examples of the supported metal include iron, silver, platinum, ruthenium, palladium, rhodium, and the like. From the viewpoint of increasing the dechlorination efficiency, palladium, ruthenium, and platinum are preferable, and palladium is more preferable. Specific examples of the metal-supported carbon compound include Pd / C (palladium-supported carbon compound), Ru / C (ruthenium-supported carbon compound), and Pt / C (platinum-supported carbon compound).

  The catalyst used in the present invention may be granular or honeycomb-shaped. In the case of particles, it is necessary to fix the inlet and outlet of the catalyst filling device with a mesh or the like, and the particle diameter in that case is preferably 75 μm to 10 mm. When it exceeds 10 mm, the specific surface area is insufficient, and when it is less than 75 μm, the mesh is clogged and the differential pressure becomes high. More preferably, it is 150 μm to 5 mm. The catalyst particles should have the same particle size as possible.

  Next, the decomposition method for dioxins in liquid according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic view showing an embodiment of the decomposition treatment method of the present invention, and shows an example of a decomposition treatment method for a liquid to be treated containing dioxins filled in a container 10. As shown in FIG. 1, in the decomposition treatment method of the present invention, first, a hydrogen donor and an alkali compound are added to a liquid to be treated to prepare a mixed solution. Next, the mixed liquid 5 is introduced into the catalyst filling device 20 installed in the microwave device 30 through the supply means (pump) 21, and the catalyst filling device 20 is continuously circulated, and then again. Return to the container 10.

  The container 10 may be provided with hydrogen donor and alkali compound supply lines 17, 18. Or although illustration is abbreviate | omitted, the apparatus (pre-tank) which stores the alkali solution which premixed the hydrogen donor and the alkali compound and dissolved the alkali compound in the hydrogen donor is installed, and this apparatus is transferred to the container 10. You may provide the supply line which supplies an alkaline solution.

  In the catalyst filling device 20 shown in FIG. 1, a catalyst packed layer filled with the above-described catalyst capable of decomposing dioxins is formed. The mixed solution 5 is introduced into the catalyst filling device 20 via the pump 21 and the supply line 22 as shown by the arrows in the figure, and flows through the catalyst packed bed. The circulation speed is not particularly limited, but is usually a space velocity (SV) of 0.05 to 0.5 cm / sec. When circulating through the catalyst filling device, the microwave device 30 irradiates microwaves and heats the catalyst filling device. Thus, when the mixed solution comes into contact with the catalyst activated and heated by the microwave, the dioxins in the mixed solution are decomposed.

  The mixed solution returned to the container through the line 23 is mixed with the mixed solution remaining in the container. When the dioxins in the mixed solution exceed a predetermined concentration, the processing operation by the catalyst filling device 20 is repeated again. However, the processing operation by the catalyst filling device 20 may be performed as necessary, and the number and timing thereof are not limited.

  Further, in the decomposition processing method of the present invention, for example, an ultrasonic generator may be provided in the vicinity of the mixed liquid inlet of the catalyst filling device 20 (illustration is omitted).

  FIG. 2 is a schematic view showing another embodiment of the decomposition processing method of the present invention, and shows another example of the decomposition processing of the liquid to be processed filled in the container 10. As shown in FIG. 2, in the decomposition method, the reaction vessel 45 is installed in the microwave device 50, and the catalyst filling device 40 is installed in the reaction vessel 45. The mixed liquid 5 is introduced into the reaction tank 45, and the catalyst filling apparatus 40 is circulated while circulating the introduced mixed liquid through the pump 51 and the line 52, whereby the catalyst activated and heated by the mixed liquid and microwaves. , Thereby decomposing dioxins in the mixed solution.

  In the embodiment shown in FIGS. 1 and 2, the catalyst filling device is installed outside the container, but the second catalyst filling device can be installed in the container 10. By installing the second catalyst filling device, there is an effect that it is possible to suppress the stop of the decomposition reaction, the precipitation of crystals, etc. by always bringing the mixed solution into contact with the catalyst even in the time zone where the microwave is not irradiated.

  FIG. 3 is a schematic side view showing an example in which the second catalyst filling device is installed in the container. Reference numeral 6 denotes the liquid level of the mixed liquid filled in the container 10. The mixed solution 5 is supplied to the second catalyst filling device 60 via the pump 16. Each pump is provided with supply lines 14 and 15 for supplying the mixed solution 5 to the second catalyst filling device 60 via the pump 16 for each pump. Thereby, a liquid mixture can be supplied to a 2nd catalyst filling apparatus, and can be made to contact a catalyst. The mounting position of the pump 16 is not particularly limited, and may be provided inside or outside the container 10.

  In the second catalyst filling device 60 shown in FIG. 3, a catalyst packed layer 62 filled with the above-described catalyst is formed. The mixed solution 5 is filled with the catalyst via the two introduction pipes (L-shaped pipes) 63 provided in the catalyst filling device 60 via the supply line 14, the pump 16, and the supply line 15 as indicated by arrows in the figure. It is introduced into the apparatus, passes through the flow holes provided in the countersink plate 61, and is supplied to the upper catalyst packed bed 62. The introduced mixed liquid flows through the catalyst packed bed 62 at a space velocity (SV) of 0.05 to 0.5 cm / sec, and the mixed liquid 5 after flowing overflows from the upper part of the second catalyst charging apparatus 60. Thus, when the mixed solution comes into contact with the catalyst, the decomposition component in the mixed solution is decomposed.

  The shape, size, and installation location in the container of the second catalyst filling device are not particularly limited. For example, the second catalyst filling device is placed on the built-in device 4 of the container 10 as illustrated in FIG. Alternatively, it may be in various forms such as being installed in a gap between the built-in device 4 and the inner wall of the container 10.

  Further, the entire second catalyst filling device need not be immersed in the mixed solution, and the upper portion thereof may be above the liquid level of the mixed solution. As shown in FIG. 3, when the upper part of the second catalyst filling device is below the liquid level of the mixed solution, the entire catalyst layer is easily fluidized by flowing the liquid from below the catalyst layer. This is preferable from the viewpoint that the number of short paths is reduced. As the second catalyst filling device, for example, the device described in Japanese Patent No. 3626960 can be used.

  In the decomposition treatment method for dioxins in liquid of the present invention, the irradiation position of the microwave is not particularly limited as long as the catalyst is irradiated on the catalyst in the reaction system, but the decomposition is promoted by increasing the catalytic activity as much as possible. It is more preferable to irradiate the catalyst in the catalyst filling device.

  In the present invention, the output, frequency, and irradiation method of the microwave applied to the catalyst filling device are not particularly limited, and may be electrically controlled so that the reaction temperature can be maintained within a predetermined range. When the output is too low, the amount of hydrogen generation is reduced, and when the output is too high, the utilization rate of the microwave is deteriorated. Therefore, it is desirable to set the range of 10 W to 20 kW while being electrically controlled. The microwave frequency is preferably 1 to 300 GHz. In the frequency range below 1 GHz or above 300 GHz, the catalyst and the hydrogen donor are not sufficiently heated. Microwave irradiation may be either continuous irradiation or intermittent irradiation, but it is preferable to perform continuous irradiation while being electrically controlled. As the microwave device, a device using a microwave generator such as a magnetron, a microwave oscillator using a solid element, or the like can be used as appropriate.

  The irradiation time and the irradiation stop time can be appropriately determined according to the type of liquid to be treated, the hydrogen donor, the reaction catalyst, etc., and may be performed until the decomposition reaction sufficiently proceeds.

  The reaction atmosphere is more preferably carried out in an inert gas because undesirable side reactions do not occur. However, since it may be difficult to procure an inert gas depending on the processing environment of the liquid to be processed, the reaction can be performed in a natural atmosphere.

  The reaction temperature is not particularly limited as long as it is equal to or lower than the boiling point of the hydrogen donor to be used, but is preferably 50 to 200 ° C, and particularly preferably 10 to 80 ° C. When the reaction temperature is less than 10 ° C., the decomposition reaction becomes insufficient. On the other hand, when the temperature exceeds 80 ° C., the decomposition reaction proceeds sufficiently, but by-products are easily generated, and the economy is inferior. From the viewpoint of balancing the suppression of side reaction products and the decomposition rate of dioxins, the reaction is more preferably 30 to 80 ° C. and at a temperature lower than the boiling point of the hydrogen donor by 10 ° C. or more (preferably 20 ° C. or more). It is good to let them.

  According to the method for decomposing dioxins of the present invention, when the dioxins are decomposed at a speed equivalent to or faster than that when hydrogen gas is blown into the reaction system from the outside, and the object to be treated is PCB, the PCB itself Is decomposed and dechlorinated. Although the mechanism is not clear, it is considered that the alkali metal radical provided from the alkali compound promotes the decomposition reaction of dioxins, and the hydrogen radical from the hydrogen donor enters therein.

  The catalyst used in the decomposition treatment of the present invention may be reused for the treatment of other objects to be treated after the regeneration treatment. The regeneration process of the catalyst may be performed by a known method. For example, the catalyst can be regenerated by washing the catalyst at 10 to 80 ° C. using an organic solvent such as acetone or a lower alcohol. There is no limitation on the washing time, and it may be appropriately determined according to the desorption status of the adsorbed compound.

  According to the decomposition treatment method of the present invention, even when the decomposition treatment of dioxins in the PCB-mixed oil is performed, the dioxins and PCB can be decomposed at the same time. By processing, it can be reused as fuel.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited only to a following example.

Example 1 (Decomposition test of dioxins contained in PCB-containing insulating oil)
A 10 L column transformer including 5 L of Type 1 No. 2 actual deteriorated insulating oil containing dioxins in the amounts shown in Table 1 and 36 ppm of PCB (biphenyl tetrachloride: KC-400) was prepared. To this, 1 L of isopropyl alcohol as a hydrogen donor and 31.4 g of KOH as an alkali were added and stirred to obtain a mixed solution.

  On the other hand, a catalyst (average particle diameter of about 1 mm) in which 5% palladium (Pd) was supported on granular activated carbon (trade name: Diahop 008) was prepared and dried at 70 ° C. for 8 hours. 236 g of this catalyst was put into a second catalyst filling device, and the upper and lower sides were sandwiched between 100 mesh nets to fill the catalyst. Two gear pumps (Model GPE-031, 12V DC) manufactured by EFNIC Co., Ltd. are attached to the outside of the pole transformer, and a Teflon tube with an inner diameter of 6 mm is attached to each pump, and one end of each pump is mixed. It was immersed in the liquid bottom, and the other end was attached to an L-shaped tube provided at the lower part of the catalyst filling device (see FIG. 3).

A part of the mixed liquid (3 L) is pumped out from the pole transformer, and the catalyst layer (filled with 600 g of the same catalyst used in the second catalyst filling device) installed in the microwave device (with the catalyst layer) The cross-sectional area was 314 cm ² ) and continuously circulated at a rate of 500 ml / min for 40 hours. Meanwhile, microwaves with a frequency of 2.54 GHz and a maximum output of 1.5 kW were irradiated while being electrically controlled, and the reaction temperature was maintained at 60 ° C.

On the other hand, the mixed liquid (3 L) remaining in the pole transformer is pumped up, and this mixed liquid is transferred from the L-shaped tube of the second catalyst filling device to the catalyst packed bed (cross-sectional area: 95 cm ² ) at 300 ml / min. The liquid was continuously circulated at a speed of 5 to circulate while overflowing the liquid from the upper part of the catalyst filling device. The space velocity (SV) at this time was 0.05 cm / sec.

  The mixed solution decomposed by the catalyst filling device was returned to the pole transformer, and the PCB concentration and dioxin concentration in the solution were measured.

(Measurement method of dioxins)
10 μl of the solution before and after the reaction was subjected to gas chromatography mass spectrometry (GC / GC) manufactured by Hewlett-Packard Co. using BPX-DXN-1 (0.15 mm ID) and BPX-DXN-2 (0.15 mm ID) manufactured by SGE as columns. MS) Measured at a column temperature of 160 ° C. to 300 ° C. with the HP6800 series To identify dioxins, create a standard chromatogram, compare the relative retention time of each appearing peak with respect to the internal standard, compare the peak area ratio and chromatogram pattern in the two monitor channels with the chromatogram obtained as a result of the measurement. I went. The dioxin concentration was determined from the peak area using a calibration curve prepared in advance.

  Table 1 shows the concentrations of dioxins and PCB in the treatment liquid before and after the decomposition treatment.

  As shown in Table 1, according to the method of the present invention, it was confirmed that dioxins (particularly polychlorodibenzofuran (PCDF) and dioxin (polychlorodibenzodioxin: PCDD)) can be rendered harmless under mild conditions. At the same time, the PCB-containing contaminated oil as a medium could be rendered harmless.

It is the schematic which shows one Embodiment of the decomposition | disassembly processing method of the dioxin in the liquid which concerns on this invention. It is the schematic which shows other embodiment of the decomposition | disassembly processing method of the dioxins in the liquid which concerns on this invention. It is a schematic side view around a container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Decomposition processing system 5 Liquid mixture 10 Container 17, 18, 22, 23, 42, 43, 52 Line 21, 41, 51 Pump 20, 40, 60 Catalyst filling apparatus 30, 50 Microwave apparatus

Claims (10)

A decomposition treatment method for decomposing dioxins contained in a liquid filled or stored in a container, wherein a liquid mixture is prepared by adding a hydrogen donor and an alkali compound to a liquid to be treated containing the dioxins. Taking out a part of the mixed solution, irradiating it with microwave while circulating it through a catalyst filling device installed in the microwave device, and then returning it to the container to decompose the dioxins in the solution A method for decomposing dioxins in liquid, characterized by 2. The dioxins in liquid according to claim 1, wherein the hydrogen donor is at least one compound selected from the group consisting of a heterocyclic compound, an amine compound, an alcohol compound, a ketone compound, and an alicyclic compound. Decomposition method. The method for decomposing dioxins in liquid according to claim 1, wherein the hydrogen donor is an alcohol compound having a boiling point of 100 ° C or lower. The method for decomposing dioxins in liquid according to any one of claims 1 to 3, wherein the addition amount of the hydrogen donor is 5 to 50% (vol) as a ratio to the liquid to be treated containing dioxins. The method for decomposing dioxins in liquid according to any one of claims 1 to 4, wherein the alkali compound is at least one compound selected from the group consisting of caustic soda, caustic potash, sodium alkoxide, potassium alkoxide, and calcium hydroxide. . The hydrogen donor and the alkali compound added to the liquid to be treated are alkali solutions having a concentration of 0.1 to 40% (w / v) obtained by dissolving an alkali compound in the hydrogen donor. A method for decomposing dioxins in liquid according to claim 1. The method for decomposing dioxins in liquid according to any one of claims 1 to 6, wherein the catalyst is at least one catalyst selected from a carbon crystal compound and a compound having a metal supported on a carrier. The method for decomposing dioxins in liquid according to claim 7, wherein the compound having a metal supported on the carrier is a palladium-supported carbon compound. The method for decomposing dioxins in liquid according to any one of claims 1 to 8, wherein the dioxins are polychlorodibenzofuran (PCDF) and / or polychlorodibenzodioxin (PCDD). The liquid treatment method for dioxins in liquid according to any one of claims 1 to 9, wherein the liquid to be treated is drainage, leachate, polluted water, polluted oil, waste lubricating oil or waste insulating oil.

Images