JPH082964B2 - Method for solidification of copolymerization of polychlorinated biphenyls - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a polychlorinated biphenyl (abbreviated as PCB) copolymerized with a metal acid ester while dechlorinating to eliminate the toxicity as a solid copolymer of metal, oxygen and biphenyl. It is about the method.

[0002]

2. Description of the Related Art Up to now, polychlorinated biphenyls are harmful when taken into the human body, as can be seen in the case of Kanemi Yusho, so methods for detoxifying them have been sought, but most of them are pyrolyzed. The purpose is to make carbon dioxide and water by radiolysis or photolysis.

The production, import and use of polychlorinated biphenyls are regulated by the law concerning regulations on examination and production of chemical substances. In addition, the Industrial Safety and Health Enforcement Ordinance Appendix 3 specifies the specified chemical substances. Being a specified chemical substance means that its handling is strictly regulated by law. On the other hand, it is said that polychlorinated biphenyls are currently stored in a solid state of about 55,000 tons nationwide, or 27,400 are used as a condenser or transformer oil in a closed system.
It is said that there are 000 tons. It has been found that when this polychlorinated biphenyl is oxidatively decomposed at low temperature, it turns into toxic benzofuran chloride or benzodioxin chloride, which causes more difficult problems. On the other hand, the stored polychlorinated biphenyls are designated as hazardous industrial waste by the law on waste treatment and cleaning, and the disposal method is specially regulated. Furthermore, the legal regulations for polychlorinated biphenyls specify that, out of the environmental standards relating to water pollution, it is not detected as an environmental standard relating to the protection of human health. In addition to this, the effluent standard is 0.003 mg / ml or less according to the designation of harmful substances in the Water Pollution Control Law, and the same limit of 0.003 mg / l or less is added to the sewage law when sewage is excluded from specified business sites into sewerage. The handling and treatment of polychlorinated biphenyls are strictly regulated by the various laws mentioned above, which reflects the severity of public opinion due to the Kanemi Yusho incident, but this is also an industrial waste treatment of polychlorinated biphenyls. It has made it difficult to do so, and caused the current situation of diffusion storage throughout the country. Furthermore, it is becoming more and more common for polychlorinated biphenyls used in Shinkansen etc. to be industrial waste.

[0004]

The conventional technique for detoxifying polychlorinated biphenyls is to completely decompose polychlorinated biphenyls into carbon dioxide gas and water.
This requires a lot of energy and labor, and
It is possible that the products in the process of decomposition may turn into more harmful substances. Therefore, from another point of view, regarding the detoxification treatment of polychlorinated biphenyls, the following three points are considered to be feasible as a policy. (1) Only dechlorination of polychlorinated biphenyls is performed. (2) The dechlorinated substance of polychlorinated biphenyl is reacted with another substance to be solidified. (3) The above reaction substances are selected so that the substance thus solidified can be used more effectively. An object of the present invention is to provide a method for effectively utilizing a polychlorinated biphenyl that has been converted into a substance other than the polychlorinated biphenyl by a mild chemical treatment in the detoxification treatment of the polychlorinated biphenyl.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, polychlorinated biphenyl and the general formula M (OR) ₄ (I) (wherein M represents titanium, zirconium or niobium,
R represents an aliphatic group), a dechlorinating copolymerization of a metal acid ester represented by the formula (1) in an organic solvent in the presence of a radical polymerization catalyst to form a solid copolymer, a polychlorinated biphenyl copolymer. A polymerization solidification method is provided.

In the present invention, polychlorinated biphenyl and a metal acid ester are subjected to a dechlorination copolymerization reaction in the presence of a radical polymerization catalyst in an organic solvent to produce a solid copolymer. The polychlorinated biphenyls include those having 2 to 10 chlorine atoms in the molecule. As the organic solvent, various solvents such as hydrocarbon solvents such as benzene, toluene, hexane, cyclohexane and the like are used, and the use of an electron donating organic solvent is particularly preferable. As the electron donating organic solvent, those containing oxygen which is an electron donating atom, sulfur atom and nitrogen atom are used. Examples of such an organic solvent include tetrahydrofuran, dioxane, dimethyl sulfoxide,
In addition to dimethylformamide and dimethylacetamide, alcohols, ethers, aromatic amines and the like can be mentioned.

In the present invention, the metal acid ester represented by the above general formula (I) is used as a reaction agent for polychlorinated biphenyls. The aliphatic group R in the general formula (I) includes a chain or cyclic group, but the carbon number thereof is not particularly limited and is 1 to 22, preferably 2 to 18. Such aliphatic groups include ethyl, propyl, butyl, hexyl, octyl, stearyl, hexenyl,
Dodecenyl, octadecenyl, cyclohexyl and the like can be mentioned. In the present invention, the use of titanic acid ester is particularly preferable from the viewpoint of availability and cost.

As the radical polymerization catalyst, a radical polymerization catalyst generally used for the polymerization of vinyl compounds,
For example, peroxides such as lauroyl peroxide, benzoyl peroxide, cumene hydroperoxide, and di-tert-butyl peroxide, azo compounds such as 2,2-azobisisobutyronitrile, and sulfides such as dibenzoyl disulfide. Etc. Further, a solid state polymerization initiator having an unsaturated valence on the surface thereof, for example, freshly crushed silica gel powder and the like can be mentioned. Solid state polymerization catalysts such as silica gel are preferable as the catalyst used in the present invention because they are safe and easy to handle.

The amount of the organic solvent used is 10 to 150 parts by weight, preferably 8 parts by weight, relative to 1 part by weight of polychlorinated biphenyl.
The proportion is from 0 to 130 parts by weight. The amount of metal acid ester used is 1 to 5 mol per mol of polychlorinated biphenyl,
The ratio is preferably 2 to 3 mol. The amount of catalyst used is
Appropriate amount, for example, 0.3 to 0.8 parts by weight, preferably 0.5 to 0.6, per 1 part by weight of polychlorinated biphenyl.
The ratio is parts by weight.

The reaction temperature in the present invention is 20 to
A temperature of 70 ° C., preferably 40-50 ° C. is adopted.
The reaction pressure is 1 to 4 kg / cm ² G, but normal pressure is sufficient. The reaction time is 10 to 120 hours, preferably 40
~ 50 hours. The reaction in the present invention is preferably carried out under light irradiation. The light in this case is 300 to 80
Light containing 0 nm, preferably 400 to 600 nm as a main wavelength is used. A white fluorescent lamp, a halogen lamp, or the like is used as the light source. This light excites p-electrons on the metal atom of the metal acid ester, increases the unpaired electron density around the metal-O bond of the metal acid ester, and accelerates the polymerization reaction.

The polymerization reaction of the present invention proceeds with dechlorination from polychlorinated biphenyls. This dechlorination is promoted by the use of an electron donating organic solvent. The copolymerization reaction of the present invention is considered to proceed according to the following reaction formula, for example.

[0012]

Embedded image (In the above formula, X represents a chlorine atom, M represents titanium, zirconium or niobium)

According to the present invention, polychlorinated biphenyls are converted into harmless solid copolymers of metal, oxygen and biphenyl.

[0014]

Next, the present invention will be described in more detail with reference to examples.

Example 1 2.7 g of polychlorinated biphenyl, 2.0 g of silica gel crushed to 100 mesh or less, butyl titanate 6.3
g, Tetrahydrofuran (500 ml) is placed in a 1 liter beaker whose top end is flattened, the watch glass with a diameter of 12 cm is covered, and light is irradiated from the outside of the beaker by two 30 W white fluorescent lamps (ring-shaped). While reacting. Evaporation of the solvent after 5 days gave an orange polymer powder. This was thoroughly washed with 50 ml of methanol and dried. In the methanol portion, 0.2 g of unreacted polychlorinated biphenyl was recovered by evaporating methanol. From this, a reaction rate of polychlorinated biphenyl of 93% is obtained. The IR absorption spectrum of the obtained polymer is shown in FIG. 1B. When compared with the polymer containing only butyl titanate (FIG. 1A), the out-of-plane vibration of hydrogen with respect to the benzene ring, which is observed when there is no C-Cl absorption and the benzene nucleus has three hydrogen atoms ( 800 Kaiser) was observed, indicating that butyl titanate and polychlorinated biphenyl were copolymerized while dechlorinating.

Example 2 As in Example 1, polychlorinated biphenyl 2.7 g, 1
2.0 g of silica gel crushed to 00 mesh or less, 6.3 g of butyl titanate, and 500 ml of benzene were placed in a 1 liter beaker whose upper end was flattened, and the diameter was 12 cm.
The lid of the watch glass was covered, and the reaction was performed while irradiating light from the outside of the beaker with two 30 W white fluorescent lamps (ring-shaped). In this case, the viscosity of the solution does not increase even after 10 days, so remove the lid and evaporate the benzene.
When about 0 ml was added and 25 ml of tetrahydrofuran was added thereto, it became a candy-like form in about 2 hours. This was dried to obtain about 6.2 g of solid.
The solid was washed with 50 ml of methanol. As for the solid portion, the silica gel portion was recovered, and 3.6 g of a polymer was obtained. Evaporate and concentrate the methanol portion to 0.8
5 g of unreacted polychlorinated biphenyl was recovered. The reaction rate of polychlorinated biphenyl was 69%. The IR absorption spectrum of the copolymer is almost the same as that shown in FIG. 1B, showing that polychlorinated biphenyls are dechlorinated and incorporated. In this case, it is considered that the reaction rate is low because benzene was not a reaction promoting solvent. Also, the reaction promoting effect of tetrahydrofuran is confirmed.

[0017]

EFFECTS OF THE INVENTION According to the present invention, polychlorinated biphenyls, which are troublesome to store and dispose as a heating medium or a liquid insulating material, can be converted into harmless solid substances. There is also a possibility of converting the copolymer into a functional polymer. INDUSTRIAL APPLICABILITY According to the present invention, not only the potential threat of various polychlorinated biphenyls to the global environment is eliminated, but also the way to effectively utilize them as resources is opened, and their industrial significance is great.

[Brief description of drawings]

FIG. 1 (A) and FIG. 1 (B) show IR spectra of the copolymer obtained in Example 1. A is the spectrum of the polymer of butyl titanate only, and B is the spectrum of the copolymer. The hydrogen absorption band of the biphenyl nucleus is indicated by an arrow.

Claims (3)

[Claims] 1. Polychlorinated biphenyl and the general formula M (OR) ₄ (wherein M represents titanium, zirconium or niobium,
Copolymerization of polychlorinated biphenyls, characterized in that a metal acid ester represented by R represents an aliphatic group) is dechlorinated in an organic solvent in the presence of a radical polymerization catalyst to form a solid polymer. Solidification method. 2. The method of claim 1, wherein the organic solvent is an electron donating organic solvent. 3. The method according to claim 1, wherein the reaction is carried out under irradiation with light.