JP2003300050A - Method for removing polychlorinated aromatic compound from pyrolysis product contaminated with polychlorinated aromatic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing polychlorinated aromatic compound from pyrolysis by-products contaminated with polychlorinated aromatic compound when a material contaminated with polychlorinated aromatic compound is treated with a vacuum heating separating apparatus. <P>SOLUTION: When the polychlorinated aromatic compound is separated from the material contaminated with polychlorinated aromatic compound with the vacuum heating separating apparatus, the pyrolysis by-products contaminated with the polychlorinated aromatic compound are extracted by a hydrocarbon solvent to remove the polychlorinated aromatic compound from the pyrolysis products. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for removing polychlorinated biphenyl from a polychlorinated biphenyl pollutant containing a polychlorinated aromatic compound which is an environmental pollutant, for example, polychlorinated biphenyl, and a decomposition treatment method. It is about.

[0002]

2. Description of the Related Art Currently, as methods legally recognized for removing polychlorinated biphenyls from polychlorinated biphenyl contaminants, there are a washing method using a solvent and a separation method using a vacuum heating separation facility. When separating paper, wood waste, etc. contaminated with polychlorinated biphenyls by a vacuum heating separation facility, thermal decomposition products such as paper, wood waste, etc. are generated together with the separated and recovered polychlorinated aromatic compounds. The thermal decomposition products include those generally called wood vinegar which are liquid at room temperature and those generally called wood tar which are resinous at room temperature. These thermal decomposition products are contaminated with high concentrations of polychlorinated biphenyls. The recovered liquid polychlorinated biphenyls are already known in the art, for example, a decomposition treatment method using an alkali metal tertiary butoxide (Japanese Patent Laid-Open No. H8 (1998) -8163).
No. -10352), a decomposition treatment method by hydrodechlorination in the presence of a palladium carbon catalyst (JP-A-9-19).
No. 4401) and the like can be detoxified. On the other hand, the thermal decomposition products contaminated with polychlorinated biphenyl are organic acid,
It is a hydrophilic liquid having a complicated composition composed of furfural, alcohols and the like, and if it is left as it is, it is difficult to make it harmless by the known technique.

[0003]

Under such circumstances, in order to promote the treatment of polychlorinated biphenyls, the pyrolysis products contaminated with polychlorinated biphenyls generated from a vacuum heating separation equipment contain the same. The polychlorinated biphenyls to be treated need to be finally treated to be harmless. It is an object of the present invention to provide a method for removing polychlorinated aromatic compounds from thermal decomposition products contaminated with such polychlorinated aromatic compounds.

[0004]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have found that a thermal decomposition product generated from a vacuum heating separation facility by a hydrocarbon solvent (this thermal decomposition product is referred to as We also found a method to effectively remove polychlorinated aromatic compounds from the thermal decomposition products), and to use known detoxification treatment technology for polychlorinated aromatic compounds removed / recovered from the pyrolysis products. The inventors have found that it can be rendered harmless by applying it, and have reached the present invention.

That is, the present invention is as follows: (1) When a polychlorinated aromatic compound is separated from a polychlorinated aromatic compound contaminant by a vacuum heating separator, the polychlorinated aromatic compound is contaminated by-product polychlorinated aromatic compound. A method of removing a polychlorinated aromatic compound from a thermal decomposition product by extracting the thermal decomposition product with a hydrocarbon solvent. (2) The method for removing a polychlorinated aromatic compound according to (1) above, wherein an insoluble polar solvent is added to a hydrocarbon solvent to improve fluidity. (3) The method for removing a polychlorinated aromatic compound according to (1) above, wherein the extraction is performed in a temperature range of 40 ° C to 100 ° C. (4) A transformer in which the pollutant of polychlorinated aromatic compound is filled with a mineral oil-based electrical insulating oil containing the polychlorinated aromatic compound or a dismantled product thereof, a capacitor filled with the polychlorinated aromatic compound, and The method for removing a polychlorinated aromatic compound according to (1), which is a transformer or a dismantled product thereof. (5) In the method for removing a polychlorinated aromatic compound described in (1) above, the polychlorinated aromatic compound transferred to the extraction solvent is further subjected to dechlorination treatment. A method of removing a compound. (6) The method for removing a polychlorinated aromatic compound according to (5) above, wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a hydrodechlorination reaction. (7) A method for removing a polychlorinated aromatic compound according to (5), wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a dechlorination reaction with a metal alcoholate. .

In the present invention, the preferred temperature for extracting the polychlorinated aromatic compound from the thermal decomposition product with a hydrocarbon solvent is room temperature to 100 ° C., preferably 40 to 100.
℃. A hydrocarbon solvent is added to the thermal decomposition product, and the mixture is stirred and mixed under this temperature condition, and the polychlorinated aromatic compound contained in the thermal decomposition product is extracted with the hydrocarbon solvent. The extraction mixture is then allowed to stand and separate. By this stationary separation, the hydrocarbon solvent layer and the thermal decomposition product layer can be separated.

By the above operation, the polychlorinated aromatic compound in the thermal decomposition product migrates to the hydrocarbon solvent layer and is efficiently removed from the thermal decomposition product. By repeating, for example, when the polychlorinated aromatic compound is polychlorinated biphenyl, the concentration of polychlorinated biphenyl in the thermal decomposition product should be a value equal to or lower than the judgment reference value of the polychlorinated biphenyl contaminant. Become. That is, as a result of carrying out the treatment method of the present invention, the thermal decomposition products are no longer pollutants of polychlorinated aromatic compounds, so that no special disposal method is required for this, and they are disposed of as ordinary waste. Is possible.

On the other hand, the hydrocarbon solvent to which the polychlorinated aromatic compound is transferred by the extraction operation can be detoxified by a known technique. For example, a decomposition treatment method using an alkali metal tertiary butoxide (JP-A-8-1035).
No. 2), a decomposition treatment method by a hydrodechlorination reaction in the presence of a palladium carbon catalyst (JP-A-9-19440).
It is possible to make it harmless by using No. 1).

The polychlorinated aromatic pollutant thermal decomposition products which are objects of the present invention are polychlorinated biphenyl transformers, polychlorinated biphenyl capacitors, polychlorinated biphenyl contaminated paper scraps, and polychlorinated biphenyl contaminated wood scraps in vacuum. These are thermal decomposition products and the like contaminated with polychlorinated biphenyls that are by-produced and recovered when separated by a heating separation facility. The pyrolysis products include wood vinegar liquid and resinous wood tar at room temperature, but the method of the present invention can be applied to any of the pyrolysis products.

The hydrocarbon solvent of the extraction solvent used in the present invention is not particularly limited, and those having a chain or cyclic molecular structure can be widely used. In the present invention, the chain hydrocarbon includes a straight chain type and a branched type having a branched carbon chain. The number of carbon atoms n may be in the range that can be used as a solvent, but is n = 5 or more in the operation, and the upper limit can be widely used such that it becomes a liquid under heating and pressurization. Among these, n = 6 (hexane) or more is preferable, and n = 10
(Decane) or higher is more preferable, and n = 14 (tetradecane) or higher is further preferable.

As the cyclic hydrocarbon, a monocyclic hydrocarbon having one ring, or a chain hydrocarbon derivative thereof, a polycyclic hydrocarbon having two or more rings, a condensed ring hydrocarbon or these Chain hydrocarbon derivatives of are included. Further, hydrides of unsaturated hydrocarbons such as hydrogenated naphthalene, hydrogenated indacene, hydrogenated fluorene and the like can also be used.

The amount of hydrocarbon used as the extraction solvent is not particularly limited, but it is preferable to select an appropriate amount and the number of extractions according to the concentration of polychlorinated aromatic compound in the thermal decomposition product. . Further, by performing a multi-stage countercurrent extraction operation, it is possible to reduce the amount of the extraction solvent used and also reduce the residual polychlorinated aromatic compound in the thermal decomposition product.

When the object to be extracted is a resin-like thermal decomposition product, sufficient fluidity cannot be obtained in the extraction step, so that the polychlorinated aromatic compound in the thermal decomposition product may not be sufficiently removed. . In such a case, by adding a polar solvent having a high solubility to the highly viscous resinous thermal decomposition product, for example, alcohols, the fluidity necessary for the extraction operation can be secured.

Alcohols added to improve fluidity have high solubility in resinous pyrolyzable products such as methanol, ethanol and ethylene glycol.
In addition, alcohols that are separated from the hydrocarbon extraction solvent are used.

The amount of extraction solvent used is not particularly limited.

The amount of alcohol used to improve the fluidity is not particularly limited,
It is preferable to use an appropriate amount depending on properties such as viscosity of the extraction target.

The extraction operation temperature is from room temperature to 100 ° C., but in order to improve the fluidity and prevent vaporization of low boiling point substances, it is preferably around 60 ° C.

After the extraction operation, it is separated into two layers by a method such as gravity separation. The polychlorinated aromatic compound is effectively removed from the thermal decomposition product layer. For example, when the polychlorinated aromatic compound is polychlorinated biphenyl, the polychlorinated biphenyl exceeding the standard value is used. Since it does not exist, it can be disposed of as ordinary waste oil or waste acid.

The extraction solvent containing the separated polychlorinated aromatic compound after the extraction operation is a known polychlorinated aromatic compound decomposition technique, for example, a decomposition treatment method using an alkali metal / tertiary / butoxide (Japanese Patent Laid-Open No. H8 (1998) -8163). No. -10352), a dechlorination treatment can be performed by a decomposition treatment method by hydrodechlorination reaction in the presence of a palladium carbon catalyst (JP-A-9-194401).

[0020]

EXAMPLES The present invention will be described below with reference to examples, but the examples do not limit the scope of the present invention.

Example 1 97 g of polychlorinated biphenyl-contaminated wood tar, 102 g of polychlorinated biphenyl-contaminated wood vinegar, and hydrocarbon-based extraction were placed in a 500 ml stainless separable four-necked flask equipped with a stirrer, a reflux condenser and a thermometer. Solvent (boiling point range 277-3
159 g of liquid paraffin having an average molecular weight of 264 at 96 ° C., hereinafter simply referred to as “hydrocarbon-based extraction solvent”) was added, and the mixture was stirred at an extraction temperature of 80 ° C. for 60 minutes for extraction operation.

After the extraction operation was completed, the upper layer hydrocarbon extraction solvent and the lower layer wood tar / wood vinegar solution mixed solution were separated with a separating funnel.

1 g of the hydrocarbon-based extraction solvent after the extraction operation was sampled as an analytical sample, and 1 g of this was extracted with n-hexane.
After making it 0 ml and cleaning it with a florisil / silica gel two-layer column, quantitative analysis was carried out by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 5000 mg / kg.

11 g of the mixed solution of wood tar and wood vinegar after the above hydrocarbon solvent extraction operation was taken as an analytical sample,
To this, 100 ml of methanol was added, and n-hexane 50 was added.
Extraction was performed 3 times with ml. The hexane extract layer was dehydrated with anhydrous sodium sulfate, concentrated with KD, cleansed with a florisil silica gel two-layer column, and quantitatively analyzed with a gas chromatograph equipped with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the mixed solution of wood tar and wood vinegar after the extraction operation was 49 mg / kg.

Example 2 A 500 ml stainless separable four-necked flask equipped with a stirrer, a reflux condenser and a thermometer was placed in a stainless tar separable four-necked flask, and the mixed solution of wood tar and wood vinegar obtained after the extraction operation of the hydrocarbon solvent obtained in Example 1 was carried out. 137 g and a hydrocarbon extraction solvent 139 g are added,
The extraction operation was performed by stirring for 60 minutes at the extraction temperature of 80 ° C.

After completion of the extraction operation, the upper layer hydrocarbon extraction solvent and the lower layer wood tar / wood vinegar solution mixed solution were separated with a separating funnel.

1 g of the hydrocarbon-based extraction solvent after the extraction operation was sampled as an analytical sample, and 1 g of this was extracted with n-hexane.
After making it 0 ml and cleaning it with a florisil / silica gel two-layer column, quantitative analysis was carried out by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 58 mg / kg.

24 g of the above-mentioned wood tar, wood vinegar solution and mixed solution after the extraction operation were sampled as an analytical sample, 100 ml of methanol was added thereto, and extraction was performed 3 times with 50 ml of n-hexane. The hexane extract layer was dehydrated with anhydrous sodium sulfate, concentrated KD, and cleansed with a florisil / silica gel two-layer column, and then quantitatively analyzed by a gas chromatograph with an ECD detector.

As a result of the analysis, the polychlorinated biphenyl concentration in the mixed solution of wood tar and wood vinegar after the extraction operation was 0.35 mg /
It was kg.

Example 3 A 500 ml stainless separable four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer was placed in a 500 ml stainless separable four-necked flask. 99 g and 98 g of a hydrocarbon-based extraction solvent were added, and the mixture was stirred at an extraction temperature of 80 ° C. for 60 minutes for extraction operation.

After the extraction operation was completed, the upper layer hydrocarbon extraction solvent and the lower layer wood tar / wood vinegar solution mixed solution were separated with a separating funnel.

1 g of the hydrocarbon-based extraction solvent after the above extraction operation was sampled as an analytical sample, and 1 g of this was extracted with n-hexane.
After making it 0 ml and cleaning it with a florisil / silica gel two-layer column, quantitative analysis was carried out by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 0.21 mg / kg.

77 g of the mixed solution of wood tar and wood vinegar after the above extraction operation was sampled as an analytical sample, 100 ml of methanol was added thereto, and extraction was performed 3 times with 50 ml of n-hexane. The hexane extract layer was dehydrated with anhydrous sodium sulfate, concentrated KD, and cleansed with a florisil / silica gel two-layer column, and then quantitatively analyzed by a gas chromatograph with an ECD detector.

As a result of the analysis, the polychlorinated biphenyl concentration in the mixed solution of wood tar and wood vinegar after the extraction operation was 0.097 mg.
It was / kg.

Example 4 71 g of polychlorinated biphenyl-contaminated wood tar, 70 g of polychlorinated biphenyl-contaminated wood vinegar, 69 g of methanol, carbonized in a 500 ml stainless separable four-necked flask equipped with a stirrer, a reflux condenser and a thermometer. Hydrogen-based extraction solvent 74
g was added, and the mixture was stirred at an extraction temperature of 60 ° C. for 30 minutes for extraction operation.

After the extraction operation was completed, the upper layer hydrocarbon extraction solvent and the lower layer wood tar and wood vinegar solution mixed solution were separated with a separating funnel.

1 g of the hydrocarbon-based extraction solvent after the above extraction operation was sampled as an analytical sample, and 1 g of this was extracted with n-hexane.
After making it 0 ml and cleaning it with a florisil / silica gel two-layer column, quantitative analysis was carried out by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 14000 mg / kg.

24 g of the above-mentioned wood tar, wood vinegar solution, and methanol mixed solution after the extraction operation were sampled as an analytical sample, and 100 ml of methanol was added to this to obtain 50 m of n-hexane.
Extraction was performed 3 times with 1. The hexane extract layer was dehydrated with anhydrous sodium sulfate, concentrated KD, and cleansed with a florisil / silica gel two-layer column, and then quantitatively analyzed by a gas chromatograph with an ECD detector.

As a result of the analysis, the polychlorinated biphenyl concentration in the mixed solution of wood tar and wood vinegar after extraction was 510 mg / kg.
Met.

Example 5 In a 500 ml stainless separable four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 153 g of a mixed solution of wood tar, wood vinegar and methanol obtained in Example 4 was obtained. And 153 g of a hydrocarbon-based extraction solvent were added, and the mixture was stirred at an extraction temperature of 60 ° C. for 30 minutes for extraction operation.

After completion of the extraction operation, the upper layer hydrocarbon extraction solvent and the lower layer wood tar, wood vinegar solution and methanol mixed solution were separated with a separating funnel.

1 g of the hydrocarbon-based extraction solvent after the extraction operation was sampled as an analytical sample, and 1 g of this was extracted with n-hexane.
After making it 0 ml and cleaning it with a florisil / silica gel two-layer column, quantitative analysis was carried out by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 460 mg / kg.

42 g of the above-mentioned wood tar, wood vinegar solution and methanol mixed solution after the extraction operation were sampled as an analytical sample, to which 100 ml of methanol was added, and 50 m of n-hexane was added.
Extraction was performed 3 times with 1. The hexane extract layer was dehydrated with anhydrous sodium sulfate, concentrated KD, and cleansed with a florisil / silica gel two-layer column, and then quantitatively analyzed by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the mixed solution of wood tar and wood vinegar after the extraction operation was 13 mg / kg.

Example 6 In a 500 ml stainless separable four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 100 g of a mixed solution of wood tar, wood vinegar and methanol after the extraction operation obtained in Example 5 and The extraction operation was performed by adding 107 g of a hydrocarbon-based extraction solvent and stirring the mixture at an extraction temperature of 60 ° C. for 30 minutes.

After completion of the extraction operation, the upper layer hydrocarbon extraction solvent and the lower layer wood tar, wood vinegar solution and methanol mixed solution were separated with a separating funnel.

1 g of the hydrocarbon-based extraction solvent after the above extraction operation was sampled as an analytical sample, and 1 g of this was extracted with n-hexane.
After making it 0 ml and cleaning it with a florisil / silica gel two-layer column, quantitative analysis was carried out by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 7.2 mg / kg.

87 g of the above-mentioned wood tar, wood vinegar solution, and methanol mixed solution after the extraction operation were sampled as an analytical sample, and 100 ml of methanol was added to this to add 50 m of n-hexane.
Extraction was performed 3 times with 1. The hexane extract layer was dehydrated with anhydrous sodium sulfate, concentrated KD, and cleansed with a florisil / silica gel two-layer column, and then quantitatively analyzed by a gas chromatograph with an ECD detector.

As a result of the analysis, the polychlorinated biphenyl concentration in the mixed solution of wood tar and wood vinegar after the extraction operation was 0.14 mg /
It was kg.

Example 7 105 g of polychlorinated biphenyl-contaminated wood tar, 101 g of polychlorinated biphenyl-contaminated wood vinegar, 99 g of methanol, carbonized in a 500 ml stainless separable four-necked flask equipped with a stirrer, a reflux condenser and a thermometer. An extraction operation was performed by adding 204 g of a hydrogen-based extraction solvent and stirring at an extraction temperature of 60 ° C. for 30 minutes.

After the extraction operation was completed, the upper layer hydrocarbon extraction solvent and the lower layer wood tar / wood vinegar solution mixed solution were separated with a separating funnel.

1 g of the hydrocarbon-based extraction solvent after the above extraction operation was taken as an analytical sample, and 1 g of this was extracted with n-hexane.
After making it 0 ml and cleaning it with a florisil / silica gel two-layer column, quantitative analysis was carried out by a gas chromatograph with an ECD detector.

As a result of the analysis, the concentration of polychlorinated biphenyl in the hydrocarbon-based extraction solvent was 3800 mg / kg.

5 equipped with a stirrer, reflux condenser and thermometer
To the 00 ml stainless separable four-necked flask, the hydrocarbon solvent (polychlorinated biphenyl concentration 3800 mg / kg) 191 after extraction and 5.8 g of potassium tertiary butoxide were added, and the reaction temperature was 250 ° C. The dechlorination reaction of polychlorinated biphenyl was carried out with stirring for 60 minutes while bubbling nitrogen.

After completion of the reaction, polychlorinated biphenyl was quantitatively analyzed by the following procedure.

After cooling the reaction mixture to room temperature, water 2
After adding 00 ml and shaking with a separating funnel and leaving it to stand, it was separated into an oil layer and an aqueous layer.

In order to analyze the polychlorinated biphenyl in the hydrocarbon-based extraction solvent after the reaction, 1 g was taken from the oil layer,
This was adjusted to 10 ml with n-hexane, cleaned with a Florisil / silica gel two-layer column, and quantitatively analyzed with a gas chromatograph equipped with an ECD detector.

As a result of analysis, the polychlorinated biphenyl concentration in the hydrocarbon solvent after the reaction was 0.13 mg / kg.

Example 8 2 equipped with a stirrer, reflux condenser, thermometer, hydrogen inlet tube
In a 000 ml glass separable four-necked flask, 120 g of the hydrocarbon solvent containing polychlorinated biphenyl after extraction operation, trichlorinated PCB (KC-300) 1
After adding 20 g, reaction solvent (hydrocarbons) 960 g, and palladium carbon 6.0 g, initial PCD before reaction
About 10 ml was taken for concentration measurement. Subsequently, the dechlorination reaction of polychlorinated biphenyl was carried out at a reaction temperature of 260 ° C. for 120 minutes while stirring while blowing hydrogen gas at a flow rate of 1.2 l / min.

After the reaction was completed, the reaction mixture before the reaction and the reaction mixture after the reaction were diluted with n-hexane and quantitatively analyzed by a gas chromatograph equipped with an ECD detector.

As a result of the analysis, PC in the reaction mixture before the reaction
The B concentration was 87,000 mg / kg, and the polychlorinated biphenyl concentration in the reaction mixture after the reaction was 0.15 mg / kg.
It was kg.

[0069]

INDUSTRIAL APPLICABILITY As described above, the present invention is effective in removing a pollutant polluted with a polychlorinated aromatic compound, which is an environmental pollutant, for example, a polychlorinated aromatic compound is polluted. The polychlorinated aromatic compound can be effectively removed from the generated hydrophilic thermal decomposition product. Furthermore, the hydrocarbon-based extraction solvent used to remove the polychlorinated aromatic compound from the hydrophilic thermal decomposition product contains the polychlorinated aromatic compound. It is possible to detoxify a polychlorinated aromatic compound by subjecting it to a dechlorination treatment by a compound decomposition treatment technique.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01F 41/00 B09B 3/00 ZAB (72) Inventor Masaaki Hosomi 2-24-16 Nakamachi, Koganei-shi, Tokyo Tokyo 2F191 BA12 BA13 BC05 BD11 4D004 AA22 AB06 AC05 CA22 CA34 CC04 DA03 DA08 4D056 AB17 AC02 AC03 AC06 CA17 CA39 DA01

Claims (7)

[Claims] 1. When a polychlorinated aromatic compound is separated from a polychlorinated aromatic compound contaminant by a vacuum heating separator, a pyrolysis product contaminated by the polychlorinated aromatic compound produced as a by-product is carbonized. A method of removing a polychlorinated aromatic compound from a thermal decomposition product by extracting with a hydrogen-based solvent. 2. The method for removing a polychlorinated aromatic compound according to claim 1, wherein an insoluble polar solvent is added to the hydrocarbon solvent to improve fluidity. 3. The method for removing a polychlorinated aromatic compound according to claim 1, wherein the extraction is performed in a temperature range of 40 ° C. to 100 ° C. 4. A polychlorinated aromatic compound pollutant filled with a mineral oil-based electrical insulating oil containing a polychlorinated aromatic compound or a dismantled product thereof, and a polychlorinated aromatic compound filled The method for removing a polychlorinated aromatic compound according to claim 1, which is a capacitor and a transformer or a dismantled product thereof. 5. The method for removing a polychlorinated aromatic compound according to claim 1, further comprising dechlorinating the polychlorinated aromatic compound transferred to the extraction solvent. Method for removing group compounds. 6. The method for removing a polychlorinated aromatic compound according to claim 5, wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a hydrodechlorination reaction. 7. The method for removing a polychlorinated aromatic compound according to claim 5, wherein the dechlorination treatment of the polychlorinated aromatic compound in the extraction solvent is a dechlorination reaction with a metal alcoholate. .