JP2010222299A - Method for extracting and device for extracting aromatic halogen compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for extracting and device for extracting an aromatic halogen compound having a hydroxy group and an aromatic halogen compound from a to-be-processed liquid containing the aromatic halogen compound having the hydroxy group. <P>SOLUTION: This method for extracting the aromatic halogen compound having the hydroxy group and the aromatic halogen compound from the to-be-processed liquid 11 containing the aromatic halogen compound having the hydroxy group includes making the pH of the process liquid 11 pH1 to pH3, and then bringing the pH-adjusted to-be-processed liquid into contact with a non-polar solvent 13 to extract the aromatic halogen compound having the hydroxy group and the aromatic halogen compound. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an extraction method and an extraction apparatus for an aromatic halogen compound, and more specifically, an aromatic halogen compound having an hydroxy group and an aromatic halogen compound from a liquid to be treated containing the aromatic halogen compound having a hydroxy group. The present invention relates to an extraction method and an extraction apparatus for an aromatic halogen compound to be extracted.

  Conventionally, aromatic halogen compounds such as harmful polychlorinated biphenyl (hereinafter sometimes referred to as “PCB”) have been used as electrical insulators such as transformers and capacitors because of their excellent electrical insulation characteristics. Also, pressure-sensitive paper and insulating paper containing PCB are used. However, since these aromatic halogen compounds are highly toxic even in a minute amount, various treatment methods for making them harmless safely have been proposed. However, since a safe detoxification treatment method has not yet been established, the present situation is that a member containing an aromatic halogen compound is stored for a long time. Similarly, waste cloths and cleaning liquids containing PCB are also stored for a long period of time.

  As a treatment method for detoxifying an aromatic halogen compound, a treatment method for dechlorination by incineration treatment or chemical decomposition is known. If the amount of the aromatic halogen compound contained in the treatment object is very small, A treatment method for efficiently detoxifying an aromatic halogen compound by detoxifying a product obtained by separating and concentrating an aromatic halogen compound from a treated product has been studied. As a method for separating and concentrating an aromatic halogen compound, there is an extraction method. As an extraction solvent, for example, dimethyl sulfoxide (DMSO) is known (see, for example, Patent Document 1).

  On the other hand, during the long-term storage described above, the aromatic halogen compound may undergo auto-oxidation by contact with air or iron rust, and a part of the halogen may be substituted with a hydroxy group. The aromatic halogen compound having a hydroxy group has a large hydrophilicity and is difficult to recover by simply extracting with DMSO. In other words, DMSO or the like having an aprotic property but a relative dielectric constant of about 50 has a problem in that extraction separation with respect to an aromatic halogen compound having a hydroxy group cannot be sufficiently obtained. Accordingly, since the aromatic halogen compound having a hydroxy group remains in the object to be treated, the object to be treated cannot be completely detoxified.

JP 2004-210945 A

  An object of the present invention is to extract an aromatic halogen compound having an hydroxy group and an aromatic halogen compound from a liquid to be treated containing the aromatic halogen compound having a hydroxy group, and an extraction method and extraction of the aromatic halogen compound. To provide an apparatus.

  In the method for extracting an aromatic halogen compound of the present invention that achieves the above object, the aromatic halogen compound having an hydroxy group and the aromatic halogen compound are extracted from a liquid to be treated containing the aromatic halogen compound having a hydroxy group. In the method, the pH of the liquid to be treated is adjusted to pH 1 to pH 3, and then the liquid to be treated and the nonpolar extraction solvent are brought into contact with each other, and the aromatic halogen compound having the hydroxy group and An aromatic halogen compound is extracted.

  The extraction solvent may be a nonpolar solvent having a relative dielectric constant of 3 or less, preferably 2.5 or less.

  An apparatus for extracting an aromatic halogen compound that achieves the above object is an apparatus for extracting the aromatic halogen compound having an hydroxy group and the aromatic halogen compound from a liquid to be treated containing the aromatic halogen compound having a hydroxy group. And adjusting the pH of the liquid to be treated to pH 1 to pH 3, and an aromatic halogen having the hydroxy group by bringing a nonpolar extraction solvent into contact with the liquid to be treated after the treatment with the pH adjusting means. It has the extraction means which extracts a compound and an aromatic halogen compound, It is characterized by the above-mentioned.

  According to the method for extracting an aromatic halogen compound of the present invention, since the pH of the liquid to be treated containing the aromatic halogen compound having a hydroxy group is set to pH 1 to pH 3, the hydroxy group is not dissociated so that the hydroxy group is not dissociated. The aromatic halogen compound and the aromatic halogen compound can be efficiently extracted with a nonpolar extraction solvent. For this reason, it can extract with a nonpolar solvent, without using an organic solvent like DMSO conventionally. Moreover, it is possible to extract an aromatic halogen compound having a hydroxy group, which has been difficult to recover.

  According to the apparatus for extracting an aromatic halogen compound of the present invention, the hydroxy group of the aromatic halogen compound is dissociated by the pH adjusting means for adjusting the pH of the treatment liquid containing the aromatic halogen compound having a hydroxy group to pH 1 to pH 3. Do not. An aromatic halogen compound having an hydroxy group and an aromatic halogen compound are obtained by contacting a liquid to be treated containing an aromatic halogen compound in which the hydroxy group is not dissociated and treated with this pH adjusting means with a nonpolar extraction solvent. Since the extraction means for extracting is provided, the aromatic halogen compound having a hydroxy group and the aromatic halogen compound can be efficiently extracted.

It is a schematic block diagram which illustrates the structure of the extraction apparatus used for the extraction method of the aromatic halogen compound of this invention.

  FIG. 1 is a schematic configuration diagram illustrating the configuration of an extraction apparatus used in the method for extracting an aromatic halogen compound of the present invention.

  In FIG. 1, 1 is a pH adjusting tank, 2 is a mixing tank, 3 is a separation tank, 4 and 5 are evaporation tanks, and 6 is a concentrate tank. The liquid 11 to be treated containing an aromatic halogen compound having a hydroxy group is supplied to the pH adjusting tank 1 and adjusted to pH 1 to pH 3 with the acid 12. The treated liquid whose pH has been adjusted is transferred to the mixing tank 2 and mixed with the nonpolar extraction solvent 13, whereby the aromatic halogen compound having a hydroxy group and the aromatic halogen compound are extracted into the extraction solvent 13. This liquid mixture is transferred to the separation tank 3 and separated by phase separation, the liquid to be treated is transferred from the lower layer to the evaporation tank 4, and the extraction solution is transferred from the upper layer to the evaporation tank 5. The liquid to be treated transferred to the evaporation tank 4 does not contain an aromatic halogen compound having a hydroxy group and an aromatic halogen compound, and is extracted as a treatment liquid 14 after evaporating and separating the extraction solvent. The extraction solution transferred to the evaporation tank 5 concentrates the aromatic halogen compound having a hydroxy group and the aromatic halogen compound by evaporating and separating the extraction solvent, and is transferred to the concentrate tank 6. The aromatic halogen compound concentrate 15 is detoxified by the aromatic halogen compound by chemical decomposition or the like.

  In the present invention, the aromatic halogen compound is a compound having an aromatic ring in which a halogen element is primarily bonded. As aromatic halogen compounds, for example, polychlorinated biphenyls (hereinafter sometimes referred to as “PCB”), dioxins, chlorobenzene, chlorotoluene, other chloro-substituted benzene derivatives, naphthalene derivatives, anthracene derivatives, and chlorine elements can be substituted. These aromatic derivatives substituted with other halogen elements are exemplified. The aromatic halogen compound having a hydroxy group is an aromatic halogen compound in which at least one halogen element of the above-described aromatic halogen compound is substituted with a hydroxy group. Such an aromatic halogen compound having a hydroxy group is produced by oxidation when the aromatic halogen compound comes into contact with air or dissolved oxygen in the liquid to be treated. Moreover, when metal oxides, such as iron rust (ferrous iron oxide), are contained in the liquid to be treated, there is a possibility that the production of an aromatic halogen compound having a hydroxy group may be promoted using this as a catalyst. In the present invention, the liquid to be treated may be any of aqueous solutions such as various types of cleaning water, oils such as insulating oil and lubricating oil, and mixed systems thereof.

In the extraction method of the present invention, the liquid to be treated 11 containing an aromatic halogen compound having a hydroxy group is adjusted to pH 1 to pH 3, preferably pH 1.3 to pH 3, by adding an acid 12 in the pH adjusting tank 1. . When the pH of the liquid to be treated exceeds pH 3, the hydroxy group is dissociated, which is not preferable for extraction of an aromatic halogen compound having a hydroxy group such as hydroxy PCB at a level of 10 ⁻⁶ mol / liter. In addition, even if it extracts with dimethylsulfoxide (DMSO), the aromatic halogen compound which has a hydroxyl group cannot fully be collect | recovered. Further, when the pH of the liquid to be treated is less than pH 1, the extractability increases, but the processing cost increases. The acid used for pH adjustment is not particularly limited as long as it can be adjusted to pH 1 to pH 3, but hydrochloric acid and sulfuric acid are preferable from the viewpoints of strength, availability, and the like.

  The pH adjustment tank is preferably a mixing tank having a stirring device and capable of temperature adjustment. Whether the liquid to be treated is aqueous or oily, it may be mixed with an acid so that the pH can be adjusted.

  The liquid to be treated whose pH has been adjusted is transferred to the mixing tank 2 and mixed and contacted with the nonpolar extraction solvent 13, whereby the aromatic halogen compound and the aromatic halogen compound having a hydroxy group in the liquid to be treated are Extracted with non-polar extraction solvent. Since the liquid to be treated is adjusted to pH 1 to pH 3, the hydroxy group is not dissociated, and the aromatic halogen compound can be easily extracted with a nonpolar extraction solvent.

  Since the nonpolar extraction solvent can be separated in a subsequent step, the amount of the nonpolar extraction solvent added to the liquid to be treated is not particularly limited. However, if the mixing ratio of the nonpolar extraction solvent to the liquid to be processed becomes excessive, the operation of concentration / dissolution is burdened, so the mixing ratio of the nonpolar extraction solvent to the liquid to be processed in the mixing tank (nonpolar extraction solvent / The volume ratio of the treatment liquid is usually 0.1 / 99.9 to 90/10, preferably 1/99 to 10/90. In addition, the mixing ratio of the liquid to be treated and the nonpolar extraction solvent can be appropriately adjusted depending on the content of the aromatic halogen compound in the liquid to be treated.

  In the present invention, the mixing tank preferably has a stirring device and can be adjusted in temperature. The temperature of the mixing tank can be appropriately adjusted according to the properties of the liquid to be treated and the nonpolar extraction solvent. In order to efficiently extract the aromatic halogen compound, it is preferable to use a substantially uniform mixed system in which the liquid to be treated and the nonpolar extraction solvent are finely dispersed. It can be appropriately set depending on the properties of the polar extraction solvent and the hydroxy aromatic halogen compound, particularly the boiling point and viscosity. When hexane is used as the nonpolar extraction solvent, it is preferably 2 to 30 ° C, more preferably 20 to 30 ° C. Further, the stirring conditions in the mixing tank are not particularly limited as long as the liquid to be treated and the nonpolar extraction solvent are in a substantially uniform mixed system.

  The nonpolar extraction solvent used in the present invention preferably has a relative dielectric constant of 3 or less, more preferably 2.5 or less. As for the relative dielectric constant of the nonpolar extraction solvent, a nonpolar extraction solvent having a small relative dielectric constant such as 2.4 for toluene, 2.3 for benzene, and 2.0 for hexane is more preferable. Further, if the relative dielectric constant of the nonpolar solvent is larger than 3, there is a risk that the extraction solvent is mixed into the aqueous or oily medium of the liquid to be treated.

  The nonpolar extraction solvent is preferably one that can be easily separated from the liquid to be treated and the aromatic halogen compound. For example, when the liquid to be treated is aqueous, the boiling point of the extraction solvent is preferably less than 100 ° C., more preferably 80 ° C. or less. When the extraction solvent has such a boiling point under normal pressure, separation from the aqueous liquid to be treated and the aromatic halogen compound becomes easy.

  Examples of the nonpolar extraction solvent used in the present invention include aliphatic hydrocarbons having 4 to 8 carbon atoms, aromatic hydrocarbons such as benzene, kerosene, and light oil. Examples of the aliphatic hydrocarbon having 4 to 8 carbon atoms include butane, pentane, hexane, heptane, and octane and isomers thereof, and examples of the aromatic hydrocarbon include benzene and toluene. Of these nonpolar extraction solvents, hexane, heptane and the like are preferable.

  As shown in FIG. 1, the aromatic halogen compound extraction apparatus of the present invention has a pH adjusting tank 1 as pH adjusting means, and a mixing tank 2 and a separating tank 3 as extracting means. Also, an evaporation tank 4 for evaporating and separating the extraction solvent from the liquid to be treated from which the aromatic halogen compound has been removed, and an evaporation tank 5 for concentrating the aromatic halogen compound by evaporating and separating the extraction solvent from the extraction liquid containing the aromatic halogen compound. It has.

  The pH adjusting means of the apparatus for extracting an aromatic halogen compound of the present invention comprises a liquid to be treated, an acid supplying means, a stirring means, and a temperature adjusting means, and the pH of the aromatic halogen compound having a hydroxy group is adjusted to pH 1 to pH 3. This prevents the hydroxy group of the aromatic halogen compound in the liquid to be treated from dissociating.

  Next, the to-be-processed liquid containing the aromatic halogen compound which the hydroxy group processed by this pH adjustment means is not dissociated is transferred to the mixing tank 2 of an extraction means. The mixing tank 2 includes a pH-adjusted liquid to be treated and a nonpolar extraction solvent supply means, agitation means, and a temperature adjustment means, and the pH-adjusted liquid to be treated and the nonpolar extraction solvent are almost uniformly and finely dispersed. By contacting as a mixed system, the aromatic halogen compound having a hydroxy group and the aromatic halogen compound are extracted. After the extraction operation, the liquid mixture of the liquid to be processed and the extraction liquid is transferred to the separation tank 3 and separated into the liquid to be processed and the extraction liquid. The separation tank only needs to have a separation function that is normally used. For example, when the liquid to be treated is aqueous, it can be separated by gravity due to a difference in specific gravity.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited by these Examples.

Preparation of sample containing aromatic halogen compound having hydroxy group 4.96 g of biphenyl, 4.22 g of 1,3,5-trichlorophenol, 10 g of NaOH, 4 g of Na ₂ CO ₃ .10H ₂ O, wood vinegar solution 30 g of the tar mixture was weighed, water was added to make up to 200 ml, and the mixture was stirred and mixed uniformly with heating to prepare a sample containing an aromatic halogen compound having a hydroxy group. The pH of this sample was 14.

Extraction operation of aromatic halogen compound having a hydroxy group 10 ml is taken from the sample obtained above, hydrochloric acid is added to adjust the sample to a predetermined pH value, and then a nonpolar extraction solvent is added and mixed. Extracting the aromatic halogen compound having a hydroxy group and allowing the sample (lower layer, extraction residue) and the extraction liquid (upper layer) to stand still are common conditions, pH value, type of extraction solvent, addition Fourteen types of extraction operations (Examples 1 to 9 and Comparative Examples 1 to 5) with different amounts and extraction temperatures as shown in Tables 1 and 2 were performed.

  The presence or absence of 1,3,5-trichlorophenol in the sample (extraction residue) extracted as described above was analyzed by the following method.

Analysis of 1,3,5-trichlorophenol 3 ml was extracted from the extracted sample (extraction residue), 100 μl of ferrous sulfate (0.5 M) and 100 μl of 30% hydrogen peroxide were added and mixed. . Next, NaOH was added to adjust the pH to about 9. A gas was collected from the obtained sample by a headspace method, and a decomposition product of 1,3,5-trichlorophenol was detected using GC-ECD (gas chromatograph having an electron capture detector). The obtained results are shown in Tables 1 and 2. The detection limit of 1,3,5-trichlorophenol by this method was about 1 μg.

  Moreover, about Example 1 and Comparative Examples 1 and 2, as a quantitative analysis of biphenyl and 1,3,5-trichlorophenol, 3 ml was extracted from the sample (extraction residue) of Example 1 and Comparative Examples 1 and 2 which were extracted. Fractionation and methylation of the hydroxyl group were performed. The obtained sample was quantitatively analyzed using GC-MS (gas chromatograph mass spectrometer).

  As a result, no biphenyl was detected from the extraction residues of Example 1 and Comparative Examples 1 and 2. On the other hand, 66 mg / kg of 1,3,5-trichlorophenol was detected from the extraction residue of Comparative Example 1 and 1.0 mg / kg from the extraction residue of Comparative Example 2. 1,3,5-trichlorophenol was not detected from the extraction residue of Example 1.

DESCRIPTION OF SYMBOLS 1 pH adjustment tank 2 Mixing tank 3 Separation tank 4,5 Evaporation tank 6 Concentrated liquid tank 11 Liquid to be processed 12 Acid 13 Extraction solvent 14 Processing liquid 15 Aromatic halogen compound concentrated liquid

Claims (3)

  A method for extracting an aromatic halogen compound having an hydroxy group and an aromatic halogen compound from a liquid to be treated containing an aromatic halogen compound having a hydroxy group, wherein the pH of the liquid to be treated is adjusted to pH 1 to pH 3. Subsequently, the aromatic halogen compound having a hydroxy group and the aromatic halogen compound are extracted by bringing the liquid to be treated whose pH has been adjusted into contact with a nonpolar extraction solvent to extract the aromatic halogen compound and the aromatic halogen compound.   The method for extracting an aromatic halogen compound according to claim 1, wherein the extraction solvent is a nonpolar solvent having a relative dielectric constant of 3 or less.   An apparatus for extracting an aromatic halogen compound having an hydroxy group and an aromatic halogen compound from a liquid to be treated containing an aromatic halogen compound having a hydroxy group, wherein the pH of the liquid to be treated is adjusted to pH 1 to pH 3. Aroma having pH adjusting means and extraction means for extracting the aromatic halogen compound having the hydroxy group and the aromatic halogen compound by bringing a non-polar extraction solvent into contact with the liquid to be treated after the treatment with the pH adjusting means. Group halogen compound extraction equipment.

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