JP2002212109A - Method for treating organic halide compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating an organic halide compound, comprising subjecting the organic halide compound or organic halide compound- containing oil to be treated to a dehalogenation treatment, by which the oil to be treated and the dehalogenated compound can easily be separated from each other and purified to recycle the materials. SOLUTION: This method for treating the organic halide compound comprises reacting the organic halide compound with an alkali metal or an alkaline earth metal and then separating the un-reacted alkali metal or alkaline earth metal solid content left in the reaction solution from the reaction solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for treating an organic halogen compound such as polychlorinated biphenyl (hereinafter abbreviated as PCB).

[0002]

2. Description of the Related Art Organic halogen compounds such as PCBs, oils and the like contaminated with the organic halogen compounds (hereinafter also referred to as oil to be treated) are generally treated by a treatment method as shown in FIG. It is a target. That is, particles of an alkali metal or an alkaline earth metal such as sodium (hereinafter, referred to as an alkali metal) are dispersed in a solvent (hereinafter, also referred to as a dispersion), and the dispersion is mixed with an oil to be treated. And reacting an organic halogen compound with a dispersion such as an alkali metal to dehalogenate the organic halogen compound.

[0003] In the treatment of such an organic halogen compound, in order to reduce the concentration of the organic halogen compound after the treatment to a predetermined value or less, or to shorten the treatment time as much as possible, a dispersion of excess alkali metal or the like is used. In many cases, the treatment is carried out in the presence of, and after the dehalogenation reaction is completed, a state in which an excessive dispersion of an alkali metal or the like remains. As described above, if a highly reactive alkaline earth metal or the like remains in the reaction solution, it is difficult to perform post-treatment. Therefore, according to the related art, water is added to the reaction solution and unreacted Alkaline earth metals and the like are hydrated, and an acid is added to neutralize the alkali solution to stabilize the solution. The oil is then separated into recovered oil and wastewater by oil / water separation for treatment.

The recovered oil thus obtained has been studied for reuse as fuel oil, insulating oil, etc.
Since the useability of these oils is determined by the properties and characteristics of the recovered oil, it is preferable to recover the oil without deterioration.

In order to safely reuse the recovered oil, it is preferable to carry out a dehalogenation treatment so that the concentration of the organic halogen compound is as low as possible.

[0006]

However, according to the above-mentioned conventional processing method, the recovered oil may deteriorate or various by-products may be mixed, and the recovered oil may be separated. There is a problem that purification becomes complicated or difficult.

Therefore, the present invention facilitates the separation and purification of the oil to be treated and the dehalogenated product when the organic halogen compound and the oil containing the organic halogen compound are subjected to the dehalogenation treatment, and the oil is reused. The task is to make it easy.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above problems, and as a result, after dehalogenation treatment, added water to unreacted alkali metals and the like remaining in the reaction solution. During the hydration treatment, hydrogen and alkali hydroxide generated by the reaction between the alkali metal and water react with the coexisting reaction solution to deteriorate the quality of the recovered oil and the like.

Therefore, the method for treating an organic halogen compound according to the present invention is characterized in that after an alkali metal or an alkaline earth metal is reacted with an organic halogen compound, a solid content in the reaction solution is separated from the reaction solution. Things.

After the reaction of the organic halogen compound with an alkali metal or an alkaline earth metal for dehalogenation, unreacted alkali metals and the like or solids such as alcoholates coexist in the reaction solution. However, by separating and removing these before the hydration treatment, the oil can be recovered without being adversely affected by the hydration treatment.

For example, when the organic halogen compound is PCB
In the case of, biphenyl compounds are produced by the dehalogenation treatment. However, according to the conventional technique, the biphenyl compounds are hydrogenated when the remaining alkali metal or the like is hydrated. Alternatively, the benzene ring is opened, and the chemical structure of the biphenyl compounds changes. However, in the method for treating an organic halogen compound according to the present invention, the solid content of the remaining alkali metal or alkaline earth metal, or an alcoholate, and the reaction solution containing the biphenyl compounds are separated beforehand, and then separately. Due to the treatment, the reaction solution can be recovered without being affected by the subsequent hydration treatment and without altering the biphenyl compounds.

Further, the method for treating an organic halogen compound according to the present invention is characterized in that the solid content is separated by centrifugally filtering the reaction solution.

The solid content is present in the reaction solution as a dispersion of very fine particles, and the reaction solution is also relatively viscous, so that it is difficult to separate it as it is. By performing centrifugal filtration, it is possible to efficiently separate the reaction solution and the solid content.

Further, the method for treating an organic halogen compound according to the present invention is characterized in that the separated reaction solution is further washed with water and then separated into oil and water to recover the oil. Since the reaction solution after the solid content is separated and removed contains salts generated by the dehalogenation reaction and other impurities, the reaction solution is washed by adding water, and then oil-water separation is performed. As a result, these impurities can be removed, and clean oil can be recovered.

Further, the method for treating an organic halogen compound according to the present invention is characterized in that water is added to the separated solid to carry out a hydration treatment. By such a treatment method, unreacted alkali metal or alkaline earth metal contained in the solid content can be hydrolyzed and decomposed, and the post-treatment can be performed safely and easily.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the method for treating an organic halogen compound according to the present invention, a schematic flow sheet in the case of treating a PCB-containing oil to be treated with a sodium dispersion is shown in FIG. Hereinafter, the embodiment will be described in detail.

First, a sodium dispersion containing insulating oil as a dispersion medium and a hydrogen donor (not shown) such as alcohol are added to the oil to be treated containing PCB and dehalogenated if necessary. . This allows the PCB in the oil to be treated
Reacts with the sodium dispersion to be dechlorinated to produce biphenyl compounds. Also, sodium dispersion and P
Salt reacts with chlorine in the CB to form a salt.
In consideration of increasing the dehalogenation rate and recovering unreacted sodium, the amount of sodium added is preferably 2.0 to 5.0 times mol of chlorine.

Since the sodium dispersion is added in a larger amount than the theoretical amount in consideration of the promotion of the dehalogenation reaction, unreacted sodium dispersion is added to the reaction solution after the dehalogenation treatment. The body remains. Further, water or alcohol is added as a hydrogen donor. When alcohol or the like is added, the alcohol reacts with a sodium dispersion to produce sodium alcoholate.

Since such a sodium dispersion, sodium alcoholate and the like are present in the reaction solution as solids, they can be separated by a general filtration method. That is, the separation can be most easily performed by a separation method utilizing a difference in specific gravity between the reaction solution and the solid content. In particular, when the particle size of the dispersion is extremely small and the viscosity of the reaction solution is high, it is preferable to use a method such as centrifugation or centrifugal filtration, and such a method enables efficient separation. . In centrifugation, separation can be performed with higher precision by operating at high speed for a long time. The temperature at the time of separation is preferably 90 ° C. or lower, which is the softening point of metallic sodium.

After the solids are separated, the oil to be treated and the dehalogenated biphenyl compounds are recovered as a reaction solution. Since the reaction solution contains impurities such as salts generated by dehalogenation, it is preferable to remove the impurities.

Therefore, the impurities and the like are dissolved in the aqueous phase by adding water to the reaction solution and stirring, and the water is removed by oil-water separation, whereby the clean oil to be treated and the biphenyl compounds are separated. Can be recovered as recovered oil.

On the other hand, the separated solids are decomposed by adding water to hydrate the alkali metal and, if necessary, neutralizing with CO ₂ or the like, and then treating as a waste liquid.

According to the method for treating an organic halogen compound, the reaction solution separated in advance is not likely to be affected by an intense chemical reaction due to the hydration treatment of the unreacted dispersion of an alkali metal or the like. Without deteriorating the quality and inadvertently producing by-products,
The oil and the like can be recovered.

As the oil to be treated, insulating oil used in transformers and condensers and any other oil containing an organic halogen compound can be used.

Example 1 In a 2000 ml four-necked flask equipped with a stirrer and a thermometer, 200 g of a 30 wt% metallic sodium dispersion containing insulating oil as a dispersion medium was charged together with 50 g of insulating oil, and reacted with nitrogen gas. After replacing the inside of the vessel, PCB (manufactured by Kanegafuchi Chemical Industry Co., Ltd., trade name: Kanechlor 1000 (hereinafter abbreviated as KC-1000)) 50
g, isopropyl alcohol (hereinafter, referred to as hydrogen donor)
A mixed solution of 69 g of IPA) and 400 g of insulating oil was added and reacted at 90 ° C. for 3 hours.

After the reaction, the reaction solution was cooled to 50 ° C. or lower, and then the reaction solution was centrifuged by a centrifugal filter (a small centrifugal filter 15A manufactured by Sanyo Chemical Instruments Co., Ltd.), and the remaining metallic sodium and sodium alcoholate were removed. And other solids were separated and removed. Thereafter, the reaction solution was washed several times with distilled water and recovered as a recovered oil. In addition, about the separated solid content, 1100 ml of water was added to decompose the remaining metal sodium, and sodium chloride and the like, which were reaction products, were dissolved in water and used as a waste liquid.

Example 2 After charging 200 g of a metallic sodium dispersion and 50 g of insulating oil into a flask in the same manner as in Example 1, 50 g of KC-1000 and 9 g of IPA were added.
0 g and 400 g of insulating oil were added and reacted at 120 ° C. for 3 hours. Others were the same as in Example 1.

(Comparative Example 1) In Example 1, after the reaction was cooled to 50 ° C, the reaction solution was added to 1100 ml of water with stirring to decompose the remaining metallic sodium.

Comparative Example 2 In Example 2, after cooling to 50 ° C. after the reaction, the reaction solution was added to 1100 ml of water while stirring to decompose the remaining metallic sodium.

(Test Method) The oil before the treatment before the dehalogenation treatment and the oil after the treatment after the dehalogenation treatment (that is, the recovered oils obtained in Examples 1 and 2 and Comparative Examples 1 and 2) were used. , Infrared absorption spectrum analyzer (JIR-100 type Fourier transform infrared spectrophotometer, manufactured by JEOL Ltd.)
It was measured by a solution method using. The analysis conditions were as follows: resolution: 4 cm ⁻¹ , number of integration: 100 times. By subtracting the spectrum of the oil before treatment from the spectrum of the oil after treatment, the absorption spectrum derived from the insulating oil was deleted, and the results of the analysis of the products generated by the reaction (FIGS. 2 and 3) were obtained.

For comparison, biphenyl and 1
Known infrared absorption spectra of -phenyl-1-chlorohexane are shown in FIGS. 4 and 5, respectively.

Referring to the results of FIG. 2 obtained for Examples 1 and 2, the absorption band characteristic of FIG. 4 (indicated by a circle in FIG. 4), which is the infrared absorption spectrum for biphenyl, has the same shape. Since it has an absorption band, in this embodiment,
It can be seen that the biphenyl produced by the dehalogenation of PCB remains without being altered.

On the other hand, the results of FIG. 3 obtained for Comparative Examples 1 and 2 are different from FIG. 4, which is the infrared absorption spectrum of biphenyl, for example, the infrared absorption spectrum of 1-phenyl-1-chlorohexane. It can be seen that there is a characteristic absorption band (shown by a circle in FIG. 5) in FIG. 5, which is a spectrum. Therefore, in the comparative example, it is considered that the biphenyl produced by the dehalogenation of PCB was altered during the hydration treatment and changed to another hydride such as 1-phenyl-1-chlorohexane.

[0034]

As described above, according to the method for treating an organic halogen compound according to the present invention, the reaction solution is not adversely affected by the hydration treatment, and therefore, the quality of the recovered oil can be prevented from deteriorating. In addition, it is possible to easily separate, recycle and reuse the oil.

[Brief description of the drawings]

FIG. 1 is a schematic flow chart showing one embodiment of a method for treating an organic halogen compound according to the present invention.

FIG. 2 is a diagram showing the results of absorption spectra obtained for Examples 1 and 2.

FIG. 3 is a diagram showing the results of absorption spectra obtained for Comparative Examples 1 and 2.

FIG. 4 is a diagram showing an infrared absorption spectrum of biphenyl.

FIG. 5 is a view showing an infrared absorption spectrum of 1-phenyl-1-chlorohexane.

FIG. 6 is a schematic flow chart showing an example of a method for treating an organic halogen compound according to a conventional technique.

Claims (5)

[Claims] 1. A method for treating an organic halogen compound, comprising reacting an organic metal compound with an alkali metal or an alkaline earth metal, and then separating a solid content in the reaction liquid from the reaction liquid. 2. The method according to claim 1, wherein the solid content is the remaining unreacted alkali metal or alkaline earth metal. 3. The method for treating an organic halogen compound according to claim 1, wherein the solid content is separated by centrifugally filtering the reaction solution. 4. The method for treating an organic halogen compound according to claim 1, wherein the separated reaction solution is washed with water and then oil-water separated to recover the oil. 5. The method for treating an organic halogen compound according to claim 1, wherein water is added to the separated solid content to perform a hydration treatment.