JP3970277B2 - Contaminated oil treatment method - Google Patents

Description

  The present invention relates to a method of dechlorinating and detoxifying oils containing a hardly decomposable organic halogen compound such as polychlorinated biphenyl (hereinafter sometimes abbreviated as PCB).

  Among various halogenated organic compounds, PCB is extremely harmful to living organisms including the human body. Therefore, it was designated as a specific chemical substance in 1973, and its manufacture, import and use are prohibited. However, after that, tens of thousands of tons of PCBs are left untreated without determining an appropriate disposal method. PCB decomposes PCB safely technically because chlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF), which are highly toxic dioxins, are by-produced at high temperature (30 to 750 ° C) decomposition. This is difficult, and various safe and efficient decomposition methods for PCBs have been studied for many years.

  As a decomposition condition of PCB, implementation at high temperature and high pressure is generally known. However, implementation under such conditions requires a high-temperature and high-pressure container and further a corrosion-resistant container and requires a lot of energy. Met. Moreover, since it is a reaction at a high temperature, it is considered that there is a high possibility that a side reaction product is generated.

  Currently, assessment is required for the construction of PCB processing facilities, so PCBs can be detoxified at sites such as transformer storage without using special equipment, and PCBs can be safely processed in large quantities. It is desired to develop a method that can be decomposed at low cost.

  Examples of methods for detoxifying oils containing PCB and the like include, for example, a method of decomposing and extracting contaminated oil in a heat-resistant and alkali-resistant solvent (Patent Document 1, etc.), and a method of dechlorinating contaminated oil in the presence of hydrogen gas (Patent Document 2 etc.), a method of treating contaminated oil with an adsorbent (Patent Document 3 etc.) and the like have been reported.

  In the method described in Patent Document 1, recovered trans-oil (hydrocarbon oil) containing a small amount of PCB is treated with 1,3-dimethyl-2-imidazolidinone (DMI) or the like in the presence of an alkaline substance such as sodium ethoxide or NaOH. After contacting with a high boiling and heat-resistant alkaline polar solvent such as sulfolane at 100 to 300 ° C. for about 2 hours, the hydrocarbon oil and the solvent are separated to remove PCB from the hydrocarbon oil. In the method described in Patent Document 2, a zeolite / nickel catalyst is added to an electrical insulating oil containing PCB, and the mixture is reacted in an autoclave filled with hydrogen gas at 200 ° C. for 5 hours. To obtain a refined oil by stirring and oil-water separation.

In the method described in Patent Document 3, PCB is selectively adsorbed and removed by bringing contaminated oil into contact with a solid acid such as magnesium silicate and adsorbing PCB onto an adsorbent.
JP-A-6-25691 (Claim 1, paragraph number 0004, Table 1 on page 3) Japanese Patent Laid-Open No. 4-202500 (Claim 1st claim, page 4, upper left column, line 11 to upper right column, line 5) JP 2003-225507 A (Claim 1, Claim 4, Paragraph Nos. 0027 to 0028, etc.)

  However, the method described in Patent Document 1 has a large amount of residual PCB, and it is necessary to lengthen the reaction time in order to sufficiently perform dechlorination, and the treatment method is also unsuitable for mass processing of PCB; This method is not practical because it requires an explosion-proof device for handling hydrogen, etc .; the method described in Patent Document 3 contacts the adsorbent adsorbing PCB with an organic solvent to extract PCB into the organic solvent. However, the PCB can be recovered at a high concentration, but the recovered PCB needs to be treated.

Therefore, the present inventors proposed a method capable of dechlorinating PCB easily and in large quantities even under normal pressure by bringing a mixed solution obtained by adding a hydrogen-donating solvent and an alkali compound into contaminated oil with a catalyst. Japanese Patent Application No. 2003-378452 ; Japanese Patent No. 36988738 , Japanese Patent Application No. 2004-191589 ; Japanese Patent No. 3626960, etc.). In the dechlorination method proposed by the present inventors, the PCB in the contaminated oil is 0.5 ppm or less by treating at room temperature for 1 to 3 weeks or under microwave heating at about 60 ° C. for 2 to 3 hours. Although it is an excellent method in that it can be made into an actual oil such as an electric insulating oil that is actually used, it contains an oxide etc. produced by the deterioration of the insulating oil, so the decomposition reaction It became a factor to inhibit.

  The present invention has been made in view of the above-described conventional problems, and is a method for treating contaminated oil, which can quickly dechlorinate and detoxify oils containing persistent organic halogen compounds in large quantities. The purpose is to provide.

The present inventors have made intensive studies for solving the above problems, by treatment dechlorination after contacting the oils containing PCB silica gel, dechlorination processing speed be significantly faster Kunar And reached the present invention.

That is, the present invention provides an oil oxide which is a substance that inhibits the decomposition reaction of a hardly decomposable organic halogen compound contained in the waste oil by bringing waste oil containing the hardly decomposable organic halogen compound into contact with silica gel . The present invention provides a method for treating contaminated oil, comprising adsorbing an additive or paint of oil to the adsorbent and then dechlorinating the waste oil after contact with the adsorbent.

  In the method for treating a contaminated oil of the present invention, it is preferable to add a hydrogen-donating solvent and an alkali compound to the waste oil after contact with the adsorbent, and dechlorinate in the presence of a catalyst.

  The catalyst is preferably at least one catalyst selected from compounds in which a metal is supported on a carrier.

  The hydrogen donating solvent is preferably 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.

According to the present invention, waste oil containing a hardly decomposable organic halogen compound is brought into contact with silica gel to remove a dechlorination reaction-inhibiting substance, whereby the contaminated oil can be quickly dechlorinated.

According to the present invention, waste oil containing a hardly decomposable organic halogen compound is brought into contact with silica gel and then dechlorinated, so that contaminated oil can be quickly rendered harmless. In addition, by adding a hydrogen-donating solvent and an alkali compound to the oil after contact with silica gel and dechlorinating in the presence of a catalyst, dechlorination can be performed at normal pressure and low temperature. There are few things. Therefore, it is possible to easily detoxify even at a site such as a transformer store, and to render a large amount of hardly decomposable organic halogen compounds harmless on a practical scale.

The method for treating contaminated oil according to the present invention is an oil which is a substance that inhibits the decomposition reaction of a hardly decomposable organic halogen compound contained in the waste oil by bringing waste oil containing a hardly decomposable organic halogen compound into contact with silica gel. The waste oil after contact with the adsorbent is subjected to dechlorination treatment after adsorbing an oxide, an oil additive, or a paint on the adsorbent. Details of the present invention will be described below.

  The contaminated oil to which the present invention is applicable and which is the treatment target of the present invention is an oil composed of at least one kind or a mixture of two or more kinds consisting of animal and vegetable oils, essential oils, resin oils, mineral oils, and is hardly decomposable. It contains an organic halogen compound. Examples of the hardly decomposable organic halogen compounds suitable for applying the method of the present invention include polychlorinated biphenyls (PCBs), monochlorobenzene (MCB), 1,2-dichlorobenzene (DCB), 1,2, Polychlorobenzene such as 4-trichlorobenzene (TCB), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), polychloroterphenyl (PCT), agricultural chemicals (aldrin, dieldrin, p, p'- DDT, p, p'-DDE), chlorofluorocarbons, halons, tetrachloroethylene, trichloroethylene, etc., which are ozone layer depleting substances, and the type thereof is not particularly limited, but preferably PCBs. It is.

  The polychlorinated biphenyls include a compound in which a chlorine atom is substituted for a biphenyl compound, and the number of substituted chlorine atoms is 1 to 10. The average number of substituted chlorine atoms is generally 2-6. In the present invention, at least one selected from these polychlorinated biphenyls or a mixture of two or more may be used.

  In general, polychlorinated biphenyls do not exist as a single compound but exist as a mixture having different numbers of chlorine atoms and different substitution positions. Therefore, there are 209 isomers based on the combination of the number of chlorine atoms and the substitution position, and more than 100 isomers exist in the commercial product.

  For example, as a coplanar PCB, 3,4,4 ′, 5-tetrachlorobiphenyl, 3,3 ′, 4,4′-tetrachlorobiphenyl, 3,3 ′, 4,4 ′, 5-pentachlorobiphenyl, 3,3 ′, 4,4 ′, 5,5′-hexachlorobiphenyl, 2,3,3 ′, 4,4′-pentachlorobiphenyl, 2,3,4,4 ′, 5-pentachlorobiphenyl, 2 , 3 ′, 4,4 ′, 5-pentachlorobiphenyl, 2 ′, 3,4,4 ′, 5-pentachlorobiphenyl, 2,3,3 ′, 4,4 ′, 5-hexachlorobiphenyl, 2, 3,3 ′, 4,4 ′, 5′-hexachlorobiphenyl, 2,3 ′, 4,4 ′, 5,5′-hexachlorobiphenyl, 2,3,3 ′, 4,4 ′, 5,5 ′ -Heptachlorobiphenyl and the like

  PCBs are usually marketed as a mixture of PCBs alone, and these are used for capacitors and transformers. Specific examples include KC-200 (biphenyl dichloride), KC-300 (biphenyl trichloride), KC-400 (biphenyl tetrachloride), KC-500 (biphenyl pentachloride), KC from Kaneka Chemical Co., Ltd. -600 (biphenyl hexachloride) and Arrochlor 1254 (54% Chlorine) manufactured by Mitsubishi Monsite Corporation. Moreover, as a mixture of commercially available polychlorinated biphenyl / halogenated aromatic compound, for example, KC-1000 (mixture of KC500 / TCB = 60/40 (mass ratio)) manufactured by Kaneka Chemical Co., Ltd., KC-1300 (Mixture of KC-300 + DCB + tetrachlorobenzene) and the like.

As an example, the distribution (mass%) of isomers of the commercial product KC-300 is shown below.
Monochrome biphenyl slightly dichlorobiphenyl 12.10%
Trichlorobiphenyl 54.98%
Tetrachlorobiphenyl 27.05%
Pentachlorobiphenyl 4.72%
Hexachlorobiphenyl 1.08%
Heptachlorobiphenyl slightly Octachlorobiphenyl 0
Nonachlorobiphenyl 0
Decachlorobiphenyl 0

In the present invention, the waste oil containing the hardly decomposable organic halogen compound is brought into contact with silica gel to selectively adsorb and remove substances that inhibit the dechlorination reaction in the waste oil. For example, waste oil such as insulating oil containing PCB such 0.5ppm~ number 1000 ppm, is continuously in contact with the silica gel, oxides selectively oils, oils of additives (antioxidants, Colorant, etc.), paint used in pole transformer containers, capacitor containers, etc. are adsorbed to the adsorbent.

The temperature at which the silica gel is brought into contact with the waste oil is not particularly limited, but is preferably 0 to 60 ° C. If the temperature is too low, the viscosity of the oil increases and handling becomes difficult. On the other hand, when the temperature is too high, oxidation of oils, vaporization of volatile hardly decomposable organic halogen compounds, and the like occur, making it difficult to control the processing environment.

The time for which the silica gel is brought into contact with the waste oil is not particularly limited because it varies depending on factors such as the viscosity of the oil, the ratio between the oil to be treated and the silica gel, and the type of silica gel (particle size, pore diameter, pore volume). As long as it does not impair the treatment effect, it may be a short time, and usually 2 minutes to 80 minutes is preferable. When the contact time is short, the removal rate of oil oxides and the like decreases, while when the contact time is too long, the removal rate reaches a peak, which is contrary to the request for rapid treatment of contaminated oil.

The method for bringing waste oils into contact with silica gel is not particularly limited, and a known continuous or batch method can be used. If you adsorption treatment by a continuous mode, for example, can be introduced the waste oil into a container filled with silica gel to handle while contacting the silica gel and waste oil. When adsorbing by batch method, add silica gel to the waste oil in the container or add the waste oil to the silica gel in the container and contact the silica gel and the waste oil for a predetermined time while stirring as necessary. Any method may be used.

Silica gel is preferably used because it selectively adsorbs oxides of oils that inhibit the dechlorination reaction and hardly adsorbs hardly decomposable organic halogen compounds. When a hard-to-decompose organohalogen compound is adsorbed on the adsorbent, a process such as dechlorination after desorption or incineration with the adsorbent is required, which complicates the contaminated oil treatment process. It is because it becomes.

Next, the waste oil after contacting with the silica gel is dechlorinated. This dechlorination method is not particularly limited, and a conventionally known method can be applied. However, when dechlorinating difficult-to-decompose PCBs, a high-temperature and high-pressure reactor or an explosion-proof device is not required, and From the viewpoint of being able to dechlorinate relatively easily even under pressure, a method of dechlorinating a mixed liquid obtained by adding a hydrogen-donating solvent and an alkali compound to waste oil after contact with silica gel in the presence of a catalyst is preferable. Such dechlorination method, Japanese Patent Application No. 2003-378452, Dotokunegai 2004-304930; Patent No. 3698738 discloses, the 2004-191589; those described in Japanese Patent No. 3626960 and the like. According to this dechlorination method, PCBs themselves are decomposed at a speed equal to or higher than that when hydrogen gas is blown into the reaction system from the outside. Although the mechanism is not clear, it is presumed that the alkali metal radical provided from the alkali compound promotes the dechlorination reaction of PCBs, and the hydrogen radical from the hydrogen donating solvent enters therein.

  The “hydrogen-donating solvent” used in the above dechlorination means a solvent capable of donating a hydrogen atom to a radical generated from a hardly decomposable organic halogen compound such as polychlorinated biphenyl. Examples thereof include organic hydrogen-donating solvents such as heterocyclic compounds, amine compounds, alcohol compounds, ketone compounds, and alicyclic compounds. By adding these compounds to waste oils, the dechlorination efficiency can be increased. Among these, alcohol compounds, ketone compounds, and alicyclic compounds are preferable from the viewpoint of safety, and alcohol compounds are particularly preferable. A hydrogen-donating solvent can be used singly or in combination of two or more.

  Here, examples of the heterocyclic compound include 1,3-dimethyl-2-imidazolidinone (DMI).

  Examples of the amine compound include dimethylethylenediamine.

  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 these alcohol compounds, aliphatic alcohols such as 2-propanol and alicyclic alcohols such as cyclohexyl alcohol are preferable from the viewpoint of decomposition efficiency. In particular, an alicyclic alcohol is preferable from the viewpoint of maintaining a high reaction temperature because of its high boiling point. On the other hand, an aliphatic alcohol such as 2-propanol having a relatively low boiling point is preferable from the viewpoint of improving the dechlorination efficiency even at a relatively low reaction temperature.

  Examples of the ketone compound include methyl ethyl ketone, cyclohexanone, tricyclododecanone, and the like.

  Examples of the alicyclic compound include tetralin and cyclohexane.

  The alkali compound used in the dechlorination can be used without limitation as long as it can accelerate the dechlorination reaction of the hardly decomposable organic halogen compound, but from the viewpoint of improving the dechlorination efficiency, Sodium alkoxide, potassium alkoxide, calcium hydroxide and the like are preferably used. Among these, caustic soda and caustic potash are particularly preferable from the viewpoint of cost and handling properties. An alkali compound can be used individually by 1 type or in combination of 2 or more types.

  The catalyst used in the dechlorination can be used without limitation as long as it can promote the dechlorination reaction of a hardly decomposable organic halogen compound (particularly polychlorinated biphenyls), and the type thereof is not particularly limited. As the catalyst, a catalyst having a long catalyst life and stable even in the presence of an alkali compound is preferably used. Preferable specific examples of the catalyst include a composite metal oxide, a carbon crystal compound, a metal oxide, or a compound in which a metal is supported on a support, from the viewpoint of increasing the dechlorination efficiency. Among these, from the viewpoint of high safety in an alkaline atmosphere, a carbon crystal compound or a compound in which a metal is supported on a carrier is preferable, and a compound in which a metal is supported on a carrier is more preferable. Examples of the carrier include carbons such as activated carbon and graphite, metal oxides such as silica gel and alumina, composite metal oxides such as zeolite, and resins such as polyethylene. Among these carriers, dechlorination efficiency A metal-supported carbon compound in which a metal is supported on a carbon support is preferable from the viewpoint of high safety and high safety in an alkaline atmosphere. A catalyst can be used individually by 1 type 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.

  Moreover, 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. % Should be good. Examples of the supported metal include iron, silver, platinum, ruthenium, palladium, rhodium and the like, and palladium, ruthenium, and platinum are preferable from the viewpoint of increasing the dechlorination efficiency. 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 particle size of the metal-supported carbon compound is preferably 75 to 300 μm. When the particle size exceeds 300 μm, the reactivity is deteriorated, and when it is less than 75 μm, the handling property is deteriorated. More preferably, 125 to 250 μm is desirable.

  The addition amount of the hydrogen donating solvent in the dechlorination is preferably 10 to 50% by mass (for oils), more preferably 10 to 40% by mass (for oils), and further preferably 10 to 30% by mass. % (For oils). If the amount added is too small, the dechlorination reaction will be insufficient. On the other hand, if the amount added is too large, the dechlorination reaction will proceed sufficiently, but by-products will be easily generated, and the economy will be poor. It becomes.

  The ratio of the above-mentioned alkali compound / hydrogen-donating solvent / refractory organic halogen compound (especially polychlorinated biphenyl) in dechlorination should be 0.001 to 5/10 / 0.000001 to 10 (molar ratio). Is preferred. The molar ratio of the three components is more preferably 0.01-3 / 10 / 0.00001-5, and particularly preferably 0.02-2 / 10 / 0.0001-1.

  If the alkali compound concentration is too low, dechlorination is difficult to proceed, and if the alkali compound concentration is too high, the alkali compound is difficult to dissolve in the hydrogen donor solvent. It is preferable to select in the range where the concentration of the alkali compound with respect to the total (mass) is 0.1 to 20% by mass.

The addition method of the hydrogen donor and the alkali compound is the order of addition of the alkali compound and the hydrogen donor, for example, simultaneous addition, divided addition, a method of adding the hydrogen donor to the waste oil and then adding the alkali compound, or vice versa. Any method may be used and is not particularly limited. Further, by high speed stirring, such as an alkali compound and hydrogen-donating solvent may be added to those with pre-mixed Go溶 solution.

  The catalyst in dechlorination is a method of dispersing in the reaction solution, a method of contacting with the reaction solution in a reaction apparatus equipped with the catalyst, or a catalyst column containing the catalyst is prepared and reacted while the reaction solution is circulated through it. It can be contacted with the reaction solution by a method or the like. The content of the catalyst in the reaction solution is preferably 0.001 to 30% by mass (for oils). In the method of dispersing the catalyst in the reaction solution, the amount of catalyst is preferably 0.001 to 10% by mass (for oils). When the amount of catalyst is too small, the amount of hydrogen generated is small, so that dechlorination is difficult to proceed. On the other hand, when the amount of catalyst is too large, stirring and mixing of the reaction system becomes difficult, which is economically disadvantageous. When the catalyst is fixed to a column or a reactor, the catalyst amount is preferably 10 to 30% by mass (for oils).

  In the above dechlorination, chemicals such as aromatic hydrocarbons may be mixed with waste oil in addition to the above-mentioned hydrogen-donating solvent, alkali compound and catalyst. By mixing the aromatic hydrocarbon, the dechlorination reaction is promoted and an increase in the viscosity of the oil can be suppressed. Examples of the aromatic hydrocarbon include toluene, ethylbenzene, cumene, xylene and the like. These aromatic hydrocarbons can be used individually by 1 type or in combination of 2 or more types. The addition amount of the aromatic hydrocarbon is preferably 5 to 80% by mass, more preferably 5 to 50% by mass with respect to the oil.

  The reaction temperature in dechlorination is preferably selected in the range of 10 to 200 ° C. When the reaction temperature is less than 10 ° C., the decomposition reaction becomes insufficient. On the other hand, when the temperature exceeds 200 ° C., the dechlorination reaction proceeds sufficiently, but by-products are likely to be generated, and the energy becomes uneconomical. It is more preferable to select in the range of 20 to 80 ° C. from the viewpoint of good energy efficiency and difficulty in producing by-products.

  The reaction time is not particularly limited because it varies depending on factors such as the kind and concentration of the hardly decomposable organic halogen compound in the oil to be treated, the amount of hydrogen donating solvent and catalyst used, the reaction temperature, etc. Selected in a range of days.

  In the dechlorination reaction, a method of heating the inside and / or outside of the reaction apparatus with a heater, microwave, or the like can be adopted, and the reaction is allowed to proceed while stirring with a stirrer if necessary. be able to. When microwaves are used for the dechlorination reaction, the microwave output, frequency, and irradiation method are not particularly limited, and microwave irradiation can be either continuous irradiation or intermittent irradiation. Alternatively, it may be electrically controlled so that the reaction temperature can be maintained within a predetermined range.

  The atmosphere of the dechlorination reaction is more preferably carried out in an inert gas because undesirable side reactions do not occur.

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

Example 1
2.5 L of real oil was prepared by adding KC-400 (biphenyl tetrachloride, manufactured by Kaneka Chemical Co., Ltd.) to 10 ppm to the used type 1 No. 2 insulating oil extracted from the pole transformer. Separately, after a glass tube was packed in a chromatographic tube having an inner diameter of 20 mmφ and a length of 500 mm, silica gel (Wakogel C-200 manufactured by Wako Pure Chemical Industries; pore diameter 6 ± 1 nm, pore volume 0.75 ± 0.10 ml / g) was used as an adsorbent. ) 160g. From the lower part of the chromatographic tube, the above-mentioned real oil was continuously passed at a rate of 500 ml / hr, and the real oil was taken out from the upper part of the chromatographic tube.

  As a result of washing the adsorbent after the actual oil treatment with a solvent, dioctyl phthalate was detected.

  Next, dechlorination was performed using a PCB decomposition apparatus schematically shown in FIG. A three-necked flask 2 is placed in the microwave generator 1, two of the three necks are used as a nitrogen introduction port 2a and an insertion port 2b of a thermometer 3, and a Dimroth cooling tube 4 is provided at the center port 2c. Thus, the reaction product was taken out of the reaction system.

  100 ml of Type 1 No. 2 oil after treatment with adsorbent, 0.6 g of KOH flakes (95%) made by Nippon Soda as an alkaline substance in a mortar, and 20 ml of isopropyl alcohol (IPA) made by Wako Pure Chemical as a hydrogen donating solvent Were mixed with a 3000 rpm homomixer for 20 minutes, and 8.0 g of activated carbon (Pd / C: manufactured by Kojima Chemical) carrying 5% palladium as a catalyst was added to a 200 ml three-necked flask. 2 was introduced.

  After introducing the mixture of each substance into the flask 2 and substituting the gas inside the flask 2 with nitrogen gas, while stirring the mixture with a magnetic stirrer, the frequency is 2.45 GHz and the maximum so that the temperature becomes constant at 60 ° C. A microwave with an output of 650 W was irradiated for 60 to 120 minutes while being electrically controlled. Nitrogen gas was allowed to flow at 50 ml / min during the reaction.

(Comparative Example 1)
2.5 L of real oil was prepared by adding KC-400 (biphenyl tetrachloride, manufactured by Kaneka Chemical Co., Ltd.) to 10 ppm to the used type 1 No. 2 insulating oil extracted from the pole transformer. As in Example 1, this was dechlorinated using a PCB decomposition apparatus schematically shown in FIG. Type 1 No. 2 real oil 100 ml, Nippon Soda KOH flakes (95%) as an alkaline substance ground in a mortar 0.6 g and Wako Pure Chemical Industries isopropyl alcohol (IPA) 40 ml as a hydrogen donating solvent at 3000 rpm homo A mixture obtained by stirring for 20 minutes with a mixer and 8.0 g of activated carbon (Pd / C: manufactured by Kojima Chemical) carrying 5% palladium as a catalyst were introduced into a three-necked flask 2 having an internal volume of 200 ml.

  After introducing the mixture of each substance into the flask 2 and substituting the gas inside the flask 2 with nitrogen gas, while stirring the mixture with a magnetic stirrer, the frequency is 2.45 GHz and the maximum so that the temperature becomes constant at 60 ° C. A microwave with an output of 650 W was irradiated for 60 to 360 minutes while being electrically controlled. Nitrogen gas was allowed to flow at 50 ml / min during the reaction.

(Evaluation methods)
The solution before and after the reaction is subjected to Sep-Pak pretreatment and then a gas chromatography mass spectrometer QP5050 (hereinafter referred to as “GC-MS”) manufactured by Shimadzu Corporation using DB1 (manufactured by J & W Scientific) as a capillary column. ) To confirm dechlorination (decomposition rate) from the change in the PCB peak area.

  Table 1 summarizes the experimental conditions and evaluation results of Example 1 and Comparative Example 1. FIG. 2 shows the relationship between reaction time and PCB concentration.

  From the results shown in Table 1, the decomposition rate of PCB was markedly reduced by contacting the actual oil with silica gel and then dechlorinating, even though the amount of isopropyl alcohol was small compared with the case where it was not contacted with silica gel. I found out that it would be faster.

It is the schematic of the PCB decomposition experiment apparatus by the microwave used by the present Example. It is a graph which shows the relationship between reaction time and PCB density | concentration in oil.

Explanation of symbols

1 Microwave generator 2 Three-neck flask 3 Thermometer 4 Dimroth condenser

Claims (4)

By contacting waste oil containing a hardly decomposable organic halogen compound with silica gel , an oxide of oil that is a decomposition reaction inhibitor of the hardly decomposable organic halogen compound contained in the waste oil, an additive for oils Alternatively, after the paint is adsorbed on the adsorbent, the waste oil after contact with the adsorbent is dechlorinated, and the contaminated oil is treated.   2. The method for treating contaminated oil according to claim 1, wherein a hydrogen donating solvent and an alkali compound are added to the waste oil after contact with the adsorbent, and dechlorination treatment is performed in the presence of a catalyst.   The method for treating contaminated oil according to claim 2, wherein the catalyst is at least one catalyst selected from compounds in which a metal is supported on a carrier.   3. The hydrogen donating solvent 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. 3. A method for treating contaminated oil according to 3.