JP2001231882A - Method for dehalogenation of organic halogen compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for decomposing a hardly decomposable halogen compound such as a polychlorobiphenyl by dehalogenation with an inexpensive calcium-contained metallic sodium dispersing material, and a method for making the halogen compound non-noxious or reusable by applying after-treatment to the dehalogeated treatment liquid. SOLUTION: An organic halogen compound is dehalogented by putting a subject to be treated including the organic halogen compound and a dehalogenation agent including a calcium-contained metallic sodium dispersing material and a nonionic surface active agent in a container, and making the contents react at the temperature of 10-120 deg.C under an inert gas atmosphere. After the dehalogeation, water is added to separate an oil layer and a water layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for easily dehalogenating hard-to-decompose halides such as polychlorinated biphenyls, which are environmental pollutants, using a calcium-containing sodium dispersion.

[0002]

2. Description of the Related Art Conventionally, fine and stable dispersions of metallic sodium have been frequently used in organic reactions due to their high reactivity, and due to their high reactivity, such as polychlorinated biphenyls which are environmental pollutants. It is used for dehalogenation of hardly decomposable halides.

In the dehalogenation of such a hardly decomposable halogen compound, it is necessary to avoid the unreacted hardly decomposable halogen compound remaining after the treatment, and to perform the dehalogenation treatment under mild conditions and quickly. It is requested to do. For this reason, when performing a dehalogenation reaction of a hardly decomposable halide such as polychlorinated biphenyls, a finely dispersed metal sodium dispersion is required as the metal sodium dispersion used. Furthermore, in manufacturing such a fine metal sodium dispersion, the use of relatively inexpensive calcium-containing metal sodium makes it possible to keep the processing cost low. It has been desired to apply it to dehalogenation of decomposable halides.

[0004] Furthermore, after dehalogenating a hardly decomposable halogen compound using a calcium-containing metal sodium dispersion, unreacted metal sodium remaining in the processing solution and post-treatment of the processing solution itself are also considered. It was also an issue to provide for safety or reuse.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to decompose a hardly decomposable halogen compound such as polychlorinated biphenyls by dehalogenation using an inexpensive calcium-containing sodium metal dispersion which has heretofore been difficult. And post-treatment of the dehalogenated treatment liquid to render it harmless or reusable.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor disperses calcium-containing metallic sodium in oil together with a nonionic surfactant, It has been found that a fine and stable calcium-containing sodium metal dispersion is produced, and by using this, a hardly decomposable halogen compound such as polychlorinated biphenyls can be decomposed under mild conditions. Furthermore, they found that by adding water to the metal sodium remaining in the dehalogenated processing solution, the remaining metal sodium could be decomposed, and the separation of the oil layer and the water layer made the subsequent processing easier. The invention has been completed.

That is, according to the present invention, an oil containing an organic halogen compound and a dehalogenation treating agent containing a calcium-containing sodium metal dispersion and a nonionic surfactant are placed in a container, and placed in an inert gas atmosphere under an inert gas atmosphere. A method of dehalogenating an organic halogen compound by reacting at 120 ° C. to dehalogenate the organic halogen compound, and adding water to a treatment liquid to decompose residual sodium metal and separating an oil layer and an aqueous layer to be harmless. It is a method that can be converted or reused.

Hereinafter, the present invention will be described in detail.

The organic halogen compound to be treated according to the present invention is a flame-retardant halogen compound, such as an aromatic organic chlorine compound or an aromatic organic bromine compound. As a substance causing contamination, treatment such as decomposition and removal is required. For example,
Polychlorinated biphenyls (PCBs), dioxins,
For aromatic organic chlorine compounds such as furans (PCDFs), dichlorodiphenyltrichloroethane (DDT), aldrin, endrin, chlordane, dieldrin, toxaphen, hexachlorobenzene, Mailex, heptachlor, and vinclozolin, and various aromatic organic compounds. Compounds substituted by bromine are mentioned. Among these, aromatic organochlorine compounds, and polychlorinated biphenyls, hexachlorobenzene, heptachlor, and vinclozolin are preferred because of their high toxicity and the high effect of decomposition by the method of the present invention. In addition, these organic halogen compounds may not only treat one kind alone, but also include two or more kinds.

[0010] The above-mentioned organic halogen compounds are mainly contained in used electric insulating oil, reaction liquid or waste liquid after organic reaction, treated products discharged from various waste treatment facilities, and the like. Or a state coexisting with various substances. Among them, as the object which exerts the effect of the present invention well, it is preferable to use an electric insulating oil represented by polychlorinated biphenyls. Furthermore, in the dehalogenation treatment of the organic halogen compound by the method of the present invention, only these objects may be used directly, but by using a mixture containing electric insulating oil and liquid paraffin, the calcium content used is reduced. The reaction efficiency of the metal sodium dispersion can be increased, and the oil layer and the water layer generated when water is added to decompose the remaining metal sodium to separate the water layer after the treatment are separated, which is effective in terms of reusing the oil layer side. Become.

In the dehalogenation treatment agent containing a calcium-containing metal sodium dispersion used in the present invention, a metal sodium dispersion having a finer particle size may be used in order to carry out dehalogenation effectively. For this reason, a metal sodium dispersion that has been subjected to a dispersion treatment using a dispersant, that is, a metal sodium dispersion containing a dispersant is preferable. Also, from the viewpoint of price, as a raw material of the metallic sodium dispersion, it is usually commercially available,
That is, 10 to 1000 ppm in metallic sodium,
Further, it is preferable to use metallic sodium containing calcium in the range of 10 to 300 ppm.

The dispersant to be added to the above-mentioned metallic sodium dispersion may have a fine particle size when producing the metallic sodium dispersion, or may be used for stabilization.
It is preferable to use nonionic surfactants, and these are commercially available in various forms such as ether type, ether ester type, phosphate ester type, ester type, and nitrogen-containing type, and any of them can be used. However, since the above effects can be further exhibited, a phosphate ester type or ether ester type is more preferably used, and a phosphate ester type is more preferably used. In addition, the amount of addition is 0.5 to 5.0% by weight, more preferably 1.0 to 3.0% by weight with respect to the metallic sodium, in order to enhance the effects of dispersion stability and miniaturization of the metallic sodium dispersion. % Is preferable.

The dehalogenating agent may be an oil having a good miscibility with an oil such as an electric insulating oil which may be contained in the object to be treated, for example, an electric insulating oil (trans oil).
Or liquid paraffin may be added. By doing this,
The dispersibility of the sodium metal dispersion is improved, so that the precipitation of sodium metal in the dehalogenation treatment agent can be suppressed, and the contact with the organic halogen compound in the object to be treated becomes efficient and quick. The treatment becomes possible, and it is also effective for separating the oil layer and the aqueous layer after the treatment.

Various devices have been reported as devices for producing such a calcium-containing sodium metal dispersion, and any of these methods may be used. For example, "Alkali Metal Dispersio" may be used.
ns "(D. VAN NOSTRAND COMPAN
Y, published in 1961). The dehalogenating agent containing the calcium-containing sodium metal dispersion is produced by adding the above-mentioned additives and the like.
In particular, the particle size of the calcium-containing metal sodium dispersion contained in the dehalogenating agent is, in terms of reactivity and dispersion stability, an average particle size of 10 μm or less,
A range of 10 μm is preferred.

[0015] The content of the calcium-containing metallic sodium dispersion used in the method of the present invention is preferably 10 to 50% by weight. This is because if the concentration is too low, the amount of dispersion medium such as oil other than metallic sodium will increase, which will increase the burden of transportation and storage, and if the concentration is too high, This is because the fluidity deteriorates and it becomes difficult to use.

According to the method of the present invention, the object to be treated containing the organic halogen compound and the dehalogenating agent containing the calcium-containing metal sodium dispersion are put in a container,
The reaction is carried out at 10 to 120 ° C. in an inert gas atmosphere to dehalogenate the organic halogen compound.

Here, the container used is not limited as long as the object of the present invention is achieved, but the metal or the surface thereof is processed with fluorine so as to have no reactivity or damage to the material used. It has a material such as metal or heat-resistant resin, etc., and is equipped with a stirrer with stirring blades etc. when stirring during the reaction, and can be hermetically sealed for reaction in an inert gas atmosphere. What is necessary is just to be provided with a heating means for maintaining a constant temperature. Also,
In the case of separating the oil layer and the aqueous layer after the treatment, those provided with a separating means are preferable. Further, the size of the container may be determined according to the amount of the processing object.

When the object to be treated and the dehalogenating agent are put into a container, the object to be treated is usually first put into a container, and the dehalogenating agent is added with or without stirring.
Here, the rate of addition when the dehalogenation treatment agent is placed in the container is not particularly limited, but since the dehalogenation of the treatment target proceeds simultaneously with the addition, the reaction temperature is maintained or excessively high. It is preferable to insert gradually so that it does not occur. Also, the amount of the dehalogenating agent to be added may be appropriately determined according to the amount of halogen present in the organic halogen compound in the object to be treated, and is equal to or greater than the amount of halogen present in the organic halogen compound. You only need to put the amount.

The inert gas used in the reaction can be used without any particular limitation as long as it is not reactive with the materials used. For example, nitrogen gas, helium, argon and the like can be used from the viewpoint of economy. Nitrogen gas is preferably used.

The temperature of the dehalogenation treatment in the present invention is preferably in the range of 10 to 120 ° C. in consideration of the dehalogenation rate and the fact that the material used is not deteriorated.
Furthermore, considering the equipment and operating costs involved in heating,
A range from 0 to 50C is preferred.

At the time of the dehalogenation treatment, a part of the solution during the treatment is appropriately collected as necessary in order to confirm the progress of the treatment, and water is added to the concentration of the organic halogen compound contained and the collected liquid, By separating the oil layer and checking the chlorine concentration in the oil layer, the progress can be grasped, and the end of the reaction can be known.

Under the above conditions, the object to be treated is subjected to dehalogenation treatment. Water is added to a container containing the treatment solution to decompose the remaining metallic sodium, thereby not only treating the organic halogen compound but also adding the water to the container. The used metallic sodium can be rendered harmless. Further, a neutralizing agent can be added after water is added. By adding water, the treatment liquid forms an aqueous layer and an oil layer, and by separating these, the oil layer can be reused. The separation means at this time is not particularly limited, but the water layer can be first discharged from the lower part of the container and separated. The separated organic layer no longer substantially contains an organic halogen compound, and thus may be used again after removing water and the like which may be mixed as necessary. Since it does not exist, it can be used as fuel or the like.

[0023]

As described above in detail, according to the present invention, the following effects are obtained as compared with the conventionally reported methods.

1) It is possible to easily and efficiently decompose a hardly decomposable halogen compound such as polychlorinated biphenyls using a calcium-containing metal sodium dispersion obtained from inexpensive calcium-containing metal sodium.

2) It is possible to decompose hardly decomposable halogen compounds such as polychlorinated biphenyls under milder conditions.

3) The treatment liquid after dehalogenation can be easily rendered harmless, and the oil can be reused.

[0027]

EXAMPLES The method of the present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, the following measurement methods were used.

<Calcium Content> The calcium in the metallic sodium used was measured by atomic absorption spectrophotometry.

<Average Particle Size> The average particle size of the obtained metallic sodium dispersion was photographed with a microscope, and the average particle size was determined by visual observation.

<ECD-GC Analysis> The trans-oil layer to be an oil layer was extracted with n-hexane, and the ECD-GC (Ele
PCBs and chlorinated biphenyls were analyzed by ctron Capture Detector (electron capture detector) gas chromatograph). The detection limit of this method is 0.5
mg / kg.

<Production of Calcium-Containing Metal Sodium Dispersion> Production Example 1 In a 70-liter reactor, 28 kg of electric insulating oil (trans oil) and 18.7 kg of metal sodium having a calcium content of 250 ppm were charged and placed in a nitrogen atmosphere. At 1
After heating to 05 ° C., the phosphate ester-based surfactant was
g, and the mixture was stirred and dispersed at a rotation speed of a stirrer of 4000 rpm for 1 hour. Cool while stirring, and when the liquid temperature is 5
When the temperature fell to 0 ° C. or lower, extraction was performed. After cooling, the average particle size was determined to be 3 microns (μm). Table 1
Shows the production conditions and the results of the average particle size of the obtained calcium-containing metallic sodium dispersion.

[0032]

[Table 1]

Production Examples 2 to 9 Using the same apparatus as in Example 1, the conditions were changed as shown in Table 1 to produce a calcium-containing metallic sodium dispersion. Table 1 also shows the production conditions and the results of the average particle size of the obtained calcium-containing metallic sodium dispersion.

Production Example 10 Oleic acid 40 was used in place of the phosphate surfactant.
The procedure was performed in the same manner as in Example 1 except that g was used. After cooling, the average particle size was determined to be 20 microns.

According to Table 1, when oleic acid is used as the surfactant in Production Example 10, the average particle size of the obtained calcium-containing sodium metal dispersion is larger than those obtained in Production Examples 1 to 9. You can see that it has become.

<Reactivity Test with Organic Halogen Compound> Using the calcium-containing sodium metal dispersions obtained in Production Examples 1 to 10, dehalogenation treatment of the organic halogen compound was performed as follows.

Example 1 1 liter of 4 equipped with thermometer, stirrer and condenser
PCB (manufactured by Kanegafuchi Chemical Industry Co., Ltd., trade name: Kanechlor 400) as an organic halogen compound in a one-necked flask
After charging 0.2 g and transformer oil (500 ml), the mixture was heated to 30 ° C. while stirring with a stirring blade, nitrogen gas was flown, and the inside of the reaction vessel was sufficiently replaced with nitrogen gas. Dispersion 6.4 g to 5
And reacted at 30 ° C. for 10 minutes. 20 after reaction
The solution was cooled to a temperature of not more than ℃ and 10 ml of water was added dropwise over 30 minutes to decompose the remaining sodium. Thereafter, the salt formed with 50 ml of water was removed by washing with water, and the trans-oil layer serving as the oil layer was analyzed by ECD-GC. As a result, PCB and chlorinated biphenyl were not detected. The water used for decomposition and the water used for washing were collected, and titrated with silver nitrate. The recovery of chlorine was 100%.

Examples 2 to 9 and Comparative Example 1 Using the apparatus of Example 1 and the calcium-containing sodium metal dispersions of Production Examples 2 to 10, a decomposition experiment of PCB was carried out under the same reaction conditions as in Example 1. . Table 2 shows the content of the change and the measurement results of the residual chlorinated biphenyl after the reaction, together with the results of Example 1.

[0039]

[Table 2]

As shown in Table 2, chlorinated biphenyl was not detected in Examples 1 to 9, whereas it was detected in Comparative Example 1. This indicates that PCB decomposition using the calcium-containing metal sodium dispersion of Production Example 10 was insufficient.

Examples 10 to 12 and Comparative Examples 2 to 4 Also, using the calcium-containing sodium metal dispersions synthesized in Production Examples 1 and 10 under the same conditions as in Example 1,
The organic halogen compounds were changed as shown in Table 3 to perform the decomposition treatment of the hardly decomposable organic halogen compounds.

[0042]

[Table 3]

According to Table 3, in Examples 10 to 12, no residue from the treated organic halogen compound was detected, whereas in Comparative Examples 2 to 4, it was detected. From this,
It can be seen that the decomposition of the organic halogen compound using the calcium-containing sodium metal dispersion of Production Example 10 was insufficient.

From the above results, it can be seen that the calcium-containing sodium metal dispersion used in the present invention can more efficiently decompose hardly decomposable halogen compounds such as polychlorinated biphenyls.

Claims (7)

[Claims] An object to be treated containing an organic halogen compound and a dehalogenating agent containing a calcium-containing sodium metal dispersion and a nonionic surfactant are placed in a container and placed in an inert gas atmosphere at 10 to 120 ° C. Wherein the organic halogen compound is dehalogenated by reacting the organic halogen compound. 2. The organic halogen compound is selected from the group consisting of polychlorinated biphenyls, dioxins, furans, dichlorodiphenyltrichloroethane, aldrin, endrin, chlordane, dieldrin, toxaphen, hexachlorobenzene, Mailex, heptachlor and vinclozolin. 2. The method for dehalogenating an organic halogen compound according to claim 1, wherein the method is one or more compounds. 3. The method according to claim 1, wherein the organic halogen compound is a polychlorinated biphenyl, hexachlorobenzene, heptachlor or vinclozolin.
3. The method for dehalogenating an organic halogen compound according to item 1. 4. An object to be treated containing an organic halogen compound,
The method for dehalogenating an organic halogen compound according to any one of claims 1 to 3, wherein the method is a mixture of an electric insulating oil or liquid paraffin and an organic halogen compound. 5. The temperature of the dehalogenation reaction is from 10 to 160 ° C.
The method for dehalogenating an organic halogen compound according to any one of claims 1 to 4, wherein 6. The dehalogenation treatment of an organic halogen compound according to claim 1, wherein water is added to decompose the remaining metal sodium after dehalogenating the organic halogen compound. Method. 7. The method for dehalogenating an organic halogen compound according to claim 6, wherein an oil layer and an aqueous layer are separated after decomposing the metallic sodium.