JP2010222476A - Method and apparatus for extracting aromatic halogen compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for extracting an aromatic halogen compound, which can efficiently extract a lipophilic aromatic halogen compound from an aromatic halogen compound-containing oil to be treated. <P>SOLUTION: In the method for extracting an aromatic halogen compound from an aromatic halogen compound-containing oil 11 to be treated, the pH of the oil 11 to be treated is adjusted to pH 9 or higher and then a polar extraction solvent 13 selected from among alcohol and ketone each having a boiling point of 80°C or lower is added to and mixed with the pH-adjusted oil to be treated. The mixture is subjected to gravity separation at a temperature of 15°C or lower to extract the aromatic halogen compound on the polar extraction solvent side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an extraction method and an extraction apparatus for an aromatic halogen compound, and more specifically, an aromatic in which a lipophilic aromatic halogen compound is efficiently extracted from an oil to be treated containing the aromatic halogen compound. The present invention relates to a halogen compound extraction method and an extraction apparatus.

  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. Since these aromatic halogen compounds are highly toxic even in trace amounts, various treatment methods for making them harmless safely have been proposed. For example, treatment methods for dechlorination by incineration or chemical decomposition are known. When the amount of aromatic halogen compound contained is very small, a method for efficiently detoxifying the aromatic halogen compound by detoxifying the separated and concentrated aromatic halogen compound from the object to be treated is examined. Has been. As a method for separating and concentrating an aromatic halogen compound, an extraction method is typical, and as an extraction solvent, for example, dimethyl sulfoxide (DMSO) is known (see, for example, Patent Document 1).

  However, since aromatic halogen compounds are highly lipophilic, when aromatic halogen compounds are extracted from the above-mentioned electrical insulating oils and lubricating oils, aromatic halogen compounds are more efficient when DMSO is used as the extraction solvent. It was difficult to extract well. Accordingly, since the aromatic halogen compound remains in the oil to be treated, the oil to be treated cannot be completely rendered harmless. Moreover, DSMO has a problem that the separation between the aromatic halogen compound and DMSO after the extraction treatment is poor and the treatment cost is high.

JP 2004-210945 A

  An object of the present invention is to provide an extraction method and an extraction apparatus for an aromatic halogen compound that efficiently extract a lipophilic aromatic halogen compound from an oil to be treated containing the aromatic halogen compound. .

  The method for extracting an aromatic halogen compound of the present invention that achieves the above object is a method for extracting the aromatic halogen compound from an oil to be treated containing an aromatic halogen compound, wherein the pH of the oil to be treated is pH 9. After the above, by adding and mixing a polar extraction solvent selected from alcohols and ketones having a boiling point of 80 ° C. or less to the oil to be treated whose pH has been adjusted, by gravity separation at a temperature of 15 ° C. or less, The aromatic halogen compound is extracted on the polar extraction solvent side.

  The polar extraction solvent may be at least one selected from methanol, ethanol, acetone, and methyl ethyl ketone. In addition, the polar extraction solvent from which the aromatic halogen compound has been extracted is adjusted to pH 1 to pH 3, and then the polar extraction solvent having the pH adjusted is brought into contact with a non-polar extraction solvent to obtain the aromatic halogen compound. It can extract to the nonpolar extraction solvent side. The polar extraction solvent from which the aromatic halogen compound has been removed by the nonpolar extraction solvent is preferably recovered by distillation fractionation.

  An apparatus for extracting an aromatic halogen compound that achieves the above object is an apparatus for extracting the aromatic halogen compound from an oil to be treated containing an aromatic halogen compound, and the pH of the oil to be treated is adjusted to pH 9 or more. By adding and mixing the first pH adjusting means and the oil to be treated treated by the first pH adjusting means, a polar extraction solvent having a boiling point of 80 ° C. or lower, and gravity-separating at a temperature of 15 ° C. or lower, It has the 1st extraction means which extracts the said aromatic halogen compound to the polar extraction solvent side, It is characterized by the above-mentioned.

  The extraction apparatus of the present invention comprises a second pH adjusting means for adjusting the pH of the polar extraction solvent containing the aromatic halogen compound taken out from the first extracting means to pH 1 to pH 3, and the second pH adjusting means. A second extraction means for extracting the aromatic halogen compound to the nonpolar extraction solvent side by bringing the nonpolar extraction solvent into contact with the polar extraction solvent treated in (1) above may be provided.

  According to the method for extracting an aromatic halogen compound of the present invention, the pH of the oil to be treated containing the aromatic halogen compound is adjusted to pH 9 or higher, and a polar extraction solvent selected from alcohols and ketones having a boiling point of 80 ° C. or lower is added. -Since it was mixed and gravity-separated at a temperature of 15 ° C or less, the aromatic halogen compound in the oil to be treated was easily extracted to the polar extraction solvent side, and the lipophilic aromatic halogen compound was removed from the oil to be treated. It can be extracted and removed efficiently.

  According to the apparatus for extracting an aromatic halogen compound of the present invention, the aromatic halogen compound can be extracted with a polar solvent by the first pH adjusting means for adjusting the pH of the oil to be treated containing the aromatic halogen compound to pH 9 or more. To do. 1st extraction which mixes the to-be-processed oil containing the aromatic halogen compound processed with this pH adjustment means, and the polar extraction solvent chosen from alcohol and a ketone whose boiling point is 80 degrees C or less, and carries out gravity separation at the temperature of 15 degrees C or less By the means, the aromatic halogen compound can be extracted to the polar extraction solvent side, and the lipophilic aromatic halogen compound can be efficiently extracted and removed from the oil to be treated.

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.

  In FIG. 1, 1 is a pH adjustment mixing tank, 2 and 6 are separation tanks, 3, 7 and 8 are evaporation tanks, 4 is a pH adjustment tank, 5 is a mixing tank, 9 is a concentrate tank, and 10 is a distillation column. . The oil to be treated 11 containing a lipophilic aromatic halogen compound is supplied to the pH adjustment mixing tank 1 and adjusted to pH 9 or more by adding an alkali 12. A polar extraction solvent 13 selected from alcohols and ketones having a boiling point of 80 ° C. or less is added to and mixed with the pH-adjusted oil to be treated. This mixed liquid is transferred to the separation tank 2 and is subjected to gravity separation at a temperature of 15 ° C. or lower, whereby the aromatic halogen compound is extracted and separated from the oil to be treated. The polar extract containing the aromatic halogen compound is discharged from the lower layer of the separation tank 2, and the treated oil from which the aromatic halogen compound has been removed is transferred from the upper layer of the separation tank 2 to the evaporation tank 3. The treated oil transferred to the evaporation tank 3 is taken out as recovered oil after evaporating and separating the polar extraction solvent. The polar extraction solvent separated by evaporation is supplied to the distillation column 10 and purified. The illustrated example is a configuration example in which two operations of pH adjustment and addition / mixing of the polar extraction solvent are performed in the pH adjustment mixing tank 1, but the pH adjustment tank and the polar extraction solvent are used instead of the pH adjustment mixing tank. It may be configured separately from the mixing tank.

  In the present invention, the polar extraction liquid discharged from the lower layer of the separation tank 2 is used as a water-soluble liquid to be treated containing an aromatic halogen compound, and the aromatic halogen compound is removed with a nonpolar extraction solvent in the steps after the pH adjustment tank 4. By extracting, it can be further concentrated and reduced in volume.

  In the pH adjusting tank 4, an acid 14 is added to the water-soluble liquid to be treated containing an aromatic halogen compound, and the pH is adjusted to pH 1 to pH 3. After the pH-adjusted water-soluble liquid to be treated is transferred to the mixing tank 5 and the nonpolar extraction solvent 15 is added and mixed, the aromatic halogen compound is extracted to the nonpolar extraction solvent 15 side. This mixed liquid is transferred to the separation tank 6 and separated by gravity separation, the water-soluble processing liquid is transferred to the evaporation tank 7 from the lower layer, and the nonpolar extraction solvent is transferred to the evaporation tank 8 from the upper layer. The water-soluble treatment liquid transferred to the evaporation tank 7 does not contain an aromatic halogen compound, and is taken out as a treatment liquid after evaporating and separating the nonpolar extraction solvent. Further, the extraction solution transferred to the evaporation tank 8 further concentrates the aromatic halogen compound by evaporating and separating the nonpolar extraction solvent, and is transferred to the concentrate tank 9. The aromatic halogen compound concentrate is detoxified by chemical decomposition or the like. The nonpolar extraction solvent separated by the evaporation tanks 7 and 8 is supplied to the distillation column 10 together with the polar extraction solvent separated by the evaporation tank 3 described above, and is purified and reused by distillation fractionation.

  In the present invention, the aromatic halogen compound is a compound having an aromatic ring in which a halogen element is primarily bonded. Examples of the aromatic halogen compound include halogen compounds having an aromatic ring such as polychlorinated biphenyl (hereinafter sometimes referred to as “PCB”), dioxins, chlorobenzene, chlorotoluene and the like. The aromatic halogen compound may be an aromatic halogen compound in which at least one halogen element of the aromatic halogen compound described above is substituted with a hydroxy group. Such an aromatic halogen compound having a hydroxy group is produced by the action of a hydroxy radical on the aromatic halogen compound when the aromatic halogen compound comes into contact with air or dissolved oxygen in the oil to be treated. Moreover, when metal oxides, such as iron rust (ferrous oxide), are contained in the oil to be treated, this serves as a catalyst to promote the production of an aromatic halogen compound having a hydroxy group. Examples of the oil to be treated include lubricating oil including PCB and the like, electrical insulating oil, mixed oil, and various liquids mixed with this.

In the extraction method of the present invention, in the pH adjustment mixing tank 1, alkali 12 is first added to oil to be treated 11 containing an aromatic halogen compound, and adjusted to pH 9 or higher, preferably pH 10 to pH 12. When the pH of the oil to be treated is less than pH 9, the action of extracting and removing the lipophilic aromatic halogen compound from the oil to be treated cannot be sufficiently obtained. For this reason, an aromatic halogen compound may remain in the oil to be treated. Further, even if the pH of the oil to be treated is higher than pH 12, the extraction rate of the aromatic halogen compound is not particularly improved, and only the treatment cost is increased. The alkali used for pH adjustment is not particularly limited as long as the oil to be treated can be adjusted to pH 9 or more. For example, alkali metal such as NaOH, KOH, Ca (OH) ₂ or alkaline earth metal The hydroxide of can be illustrated.

  Next, a polar extraction solvent 13 selected from alcohols and ketones having a boiling point of 80 ° C. or less is added to the pH adjustment mixing tank 1 and mixed and stirred. The polar extraction solvent needs to be an alcohol and / or a ketone. Alcohol and ketone have good separability from oil to be treated such as lubricating oil and electrical insulating oil, and can be easily separated by gravity. On the other hand, diethyl ether (boiling point 35 ° C.), for example, has good performance for extracting aromatic halogen compounds, but has high lipophilicity and poor separability from oil to be treated. Will remain.

  The boiling point of the alcohol and ketone used in the present invention is 80 ° C. or less, preferably 60 ° C. to 80 ° C. When the boiling point of the polar extraction solvent is higher than 80 ° C., it is difficult to perform a separation operation under normal pressure operation. Preferred examples of such a polar extraction solvent include methanol, ethanol, acetone, and methyl ethyl ketone. Of these, acetone and ethanol are preferable.

  In the present invention, the mixing ratio of the polar extraction solvent to the oil to be treated can be determined empirically by the concentration of the aromatic halogen compound in the oil to be treated. If the mixing ratio of the polar extraction solvent to the oil to be treated is insufficient, the aromatic halogen compound in the oil to be treated cannot be sufficiently extracted. Moreover, if the mixing ratio of the polar extraction solvent to the oil to be treated is larger than necessary, it takes time and effort to concentrate the aromatic halogen compound and reduce the amount of the object to be treated. Thus, the mixing ratio of the oil to be treated and the polar extraction solvent can be appropriately adjusted according to the content of the aromatic halogen compound in the oil to be treated.

  The pH adjustment mixing tank is preferably a mixing tank having a stirring device and capable of temperature adjustment. By forming a substantially uniform mixed system in which the oil to be treated and the polar extraction solvent are finely dispersed, extraction of the aromatic halogen compound can proceed efficiently. The stirring conditions in the pH adjustment mixing tank may be adjusted as appropriate according to the degree of suspension, temperature, viscosity, etc. of the liquid to be treated. For example, when the blade is agitated at about 100 rpm, the mixing time may be several tens of minutes. Moreover, in a pH adjustment mixing tank, it is good to adjust to the temperature substantially the same as gravity separation of a post process, Preferably it is 15 degrees C or less, More preferably, it is good to set it as 5-10 degreeC.

  The liquid mixture of the oil to be treated and the polar extraction solvent treated in the pH adjustment mixing tank 1 is transferred to the separation tank 2 and separated by gravity separation at 15 ° C. or lower. The polar extraction solution containing the aromatic halogen compound is discharged from the lower layer by gravity separation, and the oil to be treated from which the aromatic halogen compound has been removed is taken out from the upper layer. The temperature at which the gravity separation is performed is 15 ° C. or less, preferably 5 to 10 ° C. When the temperature of gravity separation is higher than 15 ° C., the effect of extracting the aromatic halogen compound from the oil to be treated to the polar extraction solvent side and separating it by gravity cannot be obtained sufficiently. For this reason, an aromatic halogen compound may remain in the oil to be treated.

  Since the polar extract discharged from the lower layer of the separation tank 2 contains an aromatic halogen compound, it is transferred to a step of detoxifying the aromatic halogen compound by chemical decomposition or the like, or a water-soluble solution containing the aromatic halogen compound is used. By extracting with a nonpolar extraction solvent as the liquid to be treated, the volume can be further reduced.

  In the case of further concentration and volume reduction as a water-soluble liquid to be treated containing an aromatic halogen compound, this is supplied to the pH adjustment tank 4 and pH 1 to pH 3, preferably pH 2 to pH 3 by adding acid 14. Adjust to. When the pH of the water-soluble treatment liquid exceeds pH 3, when the water-soluble treatment liquid contains an aromatic halogen compound having a hydroxy group, it becomes difficult to extract using a nonpolar solvent in the subsequent step. Moreover, even if the pH of the oil to be treated is less than pH 1, no significant improvement is observed in the extractability, and the treatment cost becomes high. The acid used for pH adjustment is not particularly limited as long as it can be adjusted to pH 1 to pH 3, and examples thereof include inorganic acids such as hydrochloric acid and sulfuric acid.

  The water-soluble treated liquid whose pH has been adjusted in the pH adjusting tank is transferred to the mixing tank 5 and mixed with and contacted with the nonpolar extraction solvent 15, so that the aromatic halogen compound in the water-soluble treated liquid becomes non- Extracted to the polar extraction solvent side. Since the water-soluble liquid to be treated is adjusted to pH 1 to pH 3, even when the aromatic halogen compound has a hydroxy group, since the hydroxy group is not dissociated, it can be easily extracted with a nonpolar extraction solvent.

  Further, the water-soluble liquid to be treated which is transferred to the mixing tank 5 has no suspension, and a clean system is extracted. For this reason, what is necessary is just to adjust suitably the mixing ratio of a water-soluble to-be-processed liquid and a nonpolar extraction solvent according to the density | concentration of the aromatic halogen compound in a water-soluble to-be-processed liquid. For example, the volume ratio of the nonpolar extraction solvent / water-soluble treatment liquid can be preferably 1/99 to 10/90.

  In the present invention, the mixing tank 5 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 water-soluble liquid to be treated and the nonpolar extraction solvent. In order to efficiently proceed with the extraction of the aromatic halogen compound, it is preferable to use a substantially uniform mixed system in which the water-soluble liquid to be treated and the nonpolar extraction solvent are finely dispersed. The temperature at which the vapor pressure at normal pressure does not increase too much, for example, 10 to 50 ° C. is preferable. Further, the mixing in the mixing tank may be a normal stirring intensity and time. For example, when the blade rotates at about 100 rpm, the residence time may be about 10 to 20 minutes.

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

  As shown in FIG. 1, the aromatic halogen compound extraction apparatus of the present invention has a pH adjustment mixing tank 1 as a first pH adjustment means, and a pH adjustment mixing tank 1 and a separation tank 2 as first extraction means. As described above, the pH adjustment mixing tank 1 serves as both the first pH adjustment means and the first extraction means. However, instead of the pH adjustment mixing tank 1, a pH adjustment tank and a mixing tank may be provided separately. Good. When the polar extraction solvent containing the aromatic halogen compound is further concentrated and reduced, the pH adjusting tank 4 is used as the second pH adjusting means, and the mixing tank 5 and the separating tank 6 are used as the second extracting means. Have. The evaporating tank 3 evaporates and separates the polar extraction solvent from the oil to be treated from which the aromatic halogen compound has been removed, the evaporating tank 7 evaporates and separates the nonpolar extraction solvent from the water-soluble to-be-treated liquid from which the aromatic halogen compound has been removed, and an aroma. An evaporating tank 8 is provided for concentrating the aromatic halogen compound by evaporating and separating the nonpolar extraction solvent from the extract containing the aromatic halogen compound. Further, the polar extraction solvent and / or the nonpolar extraction solvent separated by the evaporation tanks 3, 7, and 8 are supplied to the distillation column 10 and purified and reused.

  The first pH adjusting means of the apparatus for extracting an aromatic halogen compound of the present invention comprises a supply means and a stirring means for the oil to be treated and an alkali, and a temperature adjusting means, and the pH of the aromatic halogen compound is adjusted to pH 9 or more. This facilitates extraction of aromatic halogen compounds in the oil to be treated with a polar extraction solvent.

  Next, the oil to be treated containing the aromatic halogen compound treated by the first pH adjusting means is treated in the first extracting means. The pH-adjusting mixing tank 1 as the first extracting means includes a supply means, a stirring means, and a temperature adjusting means for the oil to be treated and the polar extraction solvent, and a temperature adjusting means. Make a uniform and finely dispersed mixed system. The liquid mixture of the oil to be treated and the polar extraction solvent is transferred to the separation tank 2 and gravity is applied to the oil to be treated from which the aromatic halogen compound has been removed under a temperature of 15 ° C. or less and the polar extraction solvent containing the aromatic halogen compound. To be separated. The separation tank only needs to have a separation function that is normally used.

  The second pH adjusting means preferably used in the present invention comprises a water-soluble liquid to be treated comprising a polar extraction solvent containing an aromatic halogen compound, an acid supply means, a stirring means and a temperature adjusting means, and an aromatic halogen compound. By adjusting the pH to pH 1 to pH 3, even when the aromatic halogen compound in the water-soluble treatment liquid has a hydroxy group, extraction with a nonpolar extraction solvent is facilitated by preventing the hydroxy group from dissociating.

  Next, the mixing tank 5 of the second extraction means includes a water-soluble liquid to be treated treated by the second pH adjustment means, a supply means for the nonpolar extraction solvent, an agitation means, and a temperature adjustment means. The aromatic halogen compound is extracted to the non-polar extraction solvent side by bringing into contact with the liquid to be treated and the non-polar extraction solvent as an almost uniform and finely dispersed mixed system. After the extraction operation, the mixed solution of the water-soluble treatment liquid and the nonpolar extraction solvent is transferred to the separation tank 6 and the non-polar extraction containing the water-soluble treatment liquid and the aromatic halogen compound from which the aromatic halogen compound has been removed. Gravity separated into solvent.

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

Preparation of samples containing aromatic halogen compounds Weigh 10.42 g of biphenyl, 10.04 g of 1,3,5-trichlorophenol, 2 g of NaOH, 30 g of pyroligneous acid / tar mixture, add concentrated hydrochloric acid and lubricating oil. The sample was made up to 200 ml and stirred and mixed uniformly while heating to prepare a sample containing an aromatic halogen compound. The pH of the obtained sample was 2.

Extraction procedure of aromatic halogen compound 10 ml is taken from the sample obtained as described above, NaOH is added to adjust the sample to a predetermined pH value, and then a polar extraction solvent is added and mixed. The common conditions are that the aromatic halogen compound is extracted to the polar extraction solvent side by allowing it to stand still for gravity separation, and the pH value, the type of polar extraction solvent, the amount added, and the temperature of gravity separation are shown in Tables 1 and 2. Nine types of extraction operations (Examples 1 to 4, Comparative Examples 1 to 5) varied as shown.

  The presence or absence of 1,3,5-trichlorophenol in the sample (extraction residue, mainly lubricating oil) taken out from the upper layer obtained by gravity separation by the above extraction operation was analyzed by the following method.

Analysis of 1,3,5-trichlorophenol 3 ml of the extracted sample (extraction residue) was dispensed into a wide-mouth bottle with a stopper of about 10 ml, and acid ferrous sulfate (7N H ₂ SO ₄ ,. 100 μl of 5M FeSO ₄ ) and 100 μl of 30% aqueous hydrogen peroxide were added, and the wide-mouth bottle was capped and shaken for 1 hour. Gas was sampled from this sample by the headspace method, and the 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.

DESCRIPTION OF SYMBOLS 1 pH adjustment mixing tank 2,6 Separation tank 3,7,8 Evaporation tank 4 pH adjustment tank 5 Mixing tank 9 Concentrated liquid tank 10 Distillation tower 11 Oil to be processed 12 Alkali 13 Polar extraction solvent 14 Acid 15 Nonpolar extraction solvent

Claims (6)

  A method for extracting an aromatic halogen compound from an oil to be treated containing an aromatic halogen compound, wherein after the pH of the oil to be treated is adjusted to pH 9 or higher, the oil to be treated whose pH is adjusted has a boiling point. Aromatic halogen compounds that extract the aromatic halogen compounds to the side of the polar extraction solvent by adding and mixing a polar extraction solvent selected from alcohols and ketones having a temperature of 80 ° C. or less and gravity separation at a temperature of 15 ° C. or less Extraction method.   The method for extracting an aromatic halogen compound according to claim 1, wherein the polar extraction solvent is at least one selected from methanol, ethanol, acetone, and methyl ethyl ketone.   The polar extraction solvent from which the aromatic halogen compound has been extracted is adjusted to pH 1 to pH 3, and then the polar extraction solvent having the pH adjusted is brought into contact with a nonpolar extraction solvent to make the aromatic halogen compound nonpolar. The method for extracting an aromatic halogen compound according to claim 1, wherein the extraction is performed on the extraction solvent side of the above.   The method for extracting an aromatic halogen compound according to claim 3, wherein the polar extraction solvent from which the aromatic halogen compound has been removed with the nonpolar extraction solvent is recovered by distillation fractionation.   An apparatus for extracting the aromatic halogen compound from the oil to be treated containing an aromatic halogen compound, the first pH adjusting means for adjusting the pH of the oil to be treated to 9 or more, and the first pH adjustment A polar extraction solvent having a boiling point of 80 ° C. or less is added to and mixed with the oil to be treated treated by the above means, and the aromatic halogen compound is extracted to the polar extraction solvent side by gravity separation at a temperature of 15 ° C. or less. An apparatus for extracting an aromatic halogen compound having one extraction means.   A second pH adjusting means for adjusting the pH of the polar extraction solvent containing the aromatic halogen compound taken out from the first extracting means to pH 1 to pH 3, and a polar extraction solvent treated by the second pH adjusting means; The apparatus for extracting an aromatic halogen compound according to claim 5, further comprising a second extraction means for extracting the aromatic halogen compound to the nonpolar extraction solvent side by contacting with a nonpolar extraction solvent.

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