JP3385992B2 - Dioxin decomposition treatment agent and decomposition treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dioxin decomposition treatment agent for decomposing dioxins in fly ash and soil, and a method for decomposing dioxins using such a decomposition treatment agent.

[0002]

2. Description of the Related Art Dioxins are a general term for polychlorinated dibenzoparadioxin, polychlorinated dibenzofuran, etc., but they cause skin and visceral disorders, and are teratogenic and carcinogenic. It is a substance. In particular, dioxins in a narrow sense, 2,3,7,8-dibenzoparadioxin, is said to be one of the most toxic substances obtained by humans.

In recent years, various pollution problems caused by such highly toxic dioxins have been pointed out, but it has been further discovered that dioxins may be produced in particular by incineration of garbage. That is, depending on the operating conditions of the garbage incinerator, dioxins are generated by incineration of the garbage, and the generated dioxins are mixed in the fly ash discharged from the garbage incinerator, or the dioxins are exhausted from the chimney of the garbage incinerator. Is included, which causes problems such as polluting the soil around the incineration plant. In view of this situation, dioxins (PCDD / PCD) adsorbed on soil or fly ash
Various chemical agents and heating methods have been proposed as methods for decomposing F).

[0004]

However, each of the above measures has a problem that they are difficult to handle or energy is too expensive. Therefore, there is a strong demand for the completion of a chemical agent capable of decomposing dioxins by simply mixing it with soil or fly ash without requiring a special device. The present invention has been made in view of such social demands, it is possible to decompose dioxins inexpensively and easily, and further, a decomposition treatment agent that can effectively utilize the soil and fly ash after the treatment, Another object is to provide such a decomposition method.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has added a composition containing oil-coated calcium oxide to fly ash and soil contaminated with dioxins. The present invention has been completed by finding that dioxins in fly ash and soil can be efficiently decomposed by mixing.

That is, the present invention is a decomposition treatment agent for dioxins, characterized in that it contains calcium oxide whose surface is oil-coated, and potassium carbonate or sodium carbonate. The decomposition treatment agent according to the present invention,
It is preferable to include a zeolite, and in this case,
An effect is exhibited that harmful heavy metals such as Cd and Pb are adsorbed on zeolite and not eluted to the outside. Further, the present invention is a decomposition treatment of dioxins, in which a decomposition treatment agent containing surface-oil-coated calcium oxide, zeolite, and potassium carbonate or sodium carbonate is added and mixed to fly ash and soil contaminated with dioxins. Is the way.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Calcium oxide used in the present invention is represented by the chemical formula of CaO and is usually called quicklime, and the production method and the like are not particularly limited.
For example, although calcium oxide is commercially available as a raw material for chemical industry and is used as a desiccant, these calcium oxides can also be used. Calcium oxide is usually industrially produced by baking limestone (calcium carbonate), but calcium oxide obtained by other methods can also be used.

The calcium oxide used in the present invention is preferably in powder form. The particle size of the powdery calcium oxide is preferably 120 to 600 mesh, more preferably 200 to 400 mesh. The grain shape is not particularly limited. In addition, the method of powdering calcium oxide and the conditions therefor are not particularly limited, but it is usually powdered in the absence of steam to avoid the reaction between calcium oxide and water.

The calcium oxide used in the agent for decomposing dioxins of the present invention is oil-coated.
The oil used for the oil coating is not particularly limited, but if corn oil or other plant oil is used, the treated soil can be effectively used for agriculture. Vegetable oils containing unsaturated fatty acids are desirable.

The method of oil coating is not particularly limited. For example, the oil to be coated is dissolved in a volatile organic solvent such as alcohol, acetone, or hexane, calcium oxide powder is added to the solution, and the volatile organic solvent is depressurized and / or heated by stirring. By removing, the oil can be coated on the surface of calcium oxide. In this case, the coating amount on calcium oxide can be adjusted by adjusting the amounts of calcium oxide, oil and organic solvent. Also,
In order to achieve a uniform coat, the amount of organic solvent is preferably 50 to 200 ml per 1 g of oil.

The heating for removing the solvent is preferably 50 ° C. or lower. Therefore, the solvent is usually removed under reduced pressure. The coating amount of oil on calcium oxide is 0.5 to 10.0 g, and preferably 1.0 to 5.0 g per 100 g of calcium oxide.

As potassium carbonate and sodium carbonate, commercially available chemicals can be used, and anhydrous salts and any hydrated salts can be used.

The dioxins decomposition treatment agent according to the present invention preferably contains zeolite in addition to oil-coated calcium oxide and potassium carbonate or sodium carbonate. Zeolite is a general term for aluminosilicate containing an alkali metal or an alkaline earth metal. In the present invention, an artificial zeolite is preferably used. The method for producing the artificial zeolite is not particularly limited, and it may be a so-called dry method or a wet method. The type and particle size of zeolite are not particularly limited, and those commercially available can be used. For example, any type of zeolite such as sodium type and calcium type can be used.

In the agent for decomposing dioxins according to the present invention, the content of zeolite and the content of potassium carbonate or sodium carbonate are respectively 100 parts by weight of calcium oxide whose surface is oil coated.
1 to 50 parts by weight and 5 to 30 parts by weight, and preferably 5 to 10 parts by weight and 10 to 20 parts by weight, respectively.

The preferred decomposition treatment agent of the present invention is calcium oxide whose surface is oil-coated, zeolite,
And potassium carbonate or sodium carbonate. The mixing method is not particularly limited. Further, each component may be separately added to fly ash, soil or the like, and after the addition to fly ash, soil or the like, the decomposition treatment agent for dioxins of the present invention may be formed therein. The agent for decomposing dioxins of the present invention may contain, in addition to the above-mentioned essential components, other components as long as the effects of the present invention are not impaired.

The decomposition treatment agent for dioxins of the present invention is
It is added to fly ash and soil contaminated with dioxins to decompose dioxins in fly ash and soil. In addition, in the present specification, the term “soil” means to include sludge. The addition amount is preferably 5 to 80 parts by weight, and more preferably 10 to 50 parts by weight with respect to 100 parts by weight of fly ash and soil.

The addition method is not particularly limited. Usually, a composition containing calcium oxide whose surface is oil-coated and potassium carbonate or sodium carbonate is added to fly ash or soil, but as described above, each component is added to fly ash or soil separately. May be. In the method of the present invention, the water content in the mixture before addition and mixing is set to 30% by weight or less based on the total solid content in order to avoid rapid heat generation after addition and mixing of the decomposition treatment agent to fly ash and soil. Preferably,
More preferably, it is 20% by weight or less. Soil other than sludge usually contains 10 to 80% by weight of water, and sludge is 1
It contains more than 00% by weight of water. On the other hand, fly ash mostly has a water content of 5% by weight or less. Therefore, it is preferable to adjust the water content before adding and mixing the decomposition treatment agent for dioxins of the present invention to fly ash or soil.

After the dioxin decomposing agent of the present invention is added to fly ash or soil and mixed, the amount of water in the mixture is adjusted to 30 to 95% by weight based on the total solid content. Preferably, the water content is more preferably 60-8
It is 0% by weight. That is, it is preferable to add and mix the dioxins decomposition treating agent of the present invention to fly ash and soil, and then add and mix water so as to be in the above range. If the water content exceeds the above range, the decomposition rate of dioxins decreases.

As described above, the fly ash and soil to which the decomposition treatment agent for dioxins of the present invention has been added, after optionally adding water and other components, are sufficiently mixed and left to stand. If water is added, 130 ° C -1 in about 1 hour
It heats up to 70 ° C and returns to room temperature in about 3 days. In order to sufficiently decompose dioxins, it is preferable that the standing period is long, but the standing period is preferably 7 days or more. When left as it is, the water content evaporates due to heat generation and the water content decreases, but in the normal case, it is preferable not to add water. If left as such, fly ash and dioxins in the soil will be decomposed,
Fly ash and soil that do not cause environmental pollution can be obtained.

[0020]

The dioxins decomposition treatment agent of the present invention efficiently decomposes dioxins when added to and mixed with fly ash, soil or the like contaminated with dioxins. Therefore, by the method for treating dioxins using the dioxins decomposition treatment agent of the present invention, it is possible to efficiently decompose dioxins contained in fly ash or soil, and fly ash or soil that does not cause environmental pollution. Can be easily obtained. In addition, when the zeolite is contained, the effect that the harmful heavy metals such as Cd and Pb are adsorbed on the zeolite and not eluted outside is exhibited.

[0021]

EXAMPLES The present invention will now be described by way of examples, which are merely examples and do not limit the scope of the present invention. Example 1 1 g of commercially available corn oil is dissolved in 100 ml of acetone. This solution and 100 g of calcium oxide powder with an average particle size of 300 mesh are added to a rotary evaporator. Acetone solution of corn oil and calcium oxide powder are heated and agitated by stirring with a rotary evaporator to remove acetone. After sufficiently removing acetone, the obtained powder was taken out from the rotary evaporator to obtain a corn oil-coated calcium oxide powder.

A small amount of this calcium oxide powder was added to water, but unlike calcium oxide powder not coated with oil, it did not react immediately with water and did not generate heat. 100 g of the oil-coated calcium oxide powder thus obtained was mixed with artificial zeolite (C
5 g of a type) and 10 g of potassium carbonate (reagent) were added and mixed well to obtain a decomposition treatment agent for dioxins.

Example 2 20 g of this decomposition agent for dioxins was added to 100 g of fly ash (PCDD / DF; 0.25 ng TEQ / g dry weight) from an incinerator and mixed well. Then, water was added so that the water content was 80% based on the total solid content, and the mixture was stirred again and left at room temperature. The amount of dioxins immediately after addition and mixing of the decomposition treatment agent and after standing for 1 week (PC
The results of measuring the DD / DF value) are shown below. Immediately after addition and mixing: 0.207 ng TEQ / g dry weight and left for 1 week: 0.0041 ng TEQ / g dry weight, that is, the decomposition rate of dioxins after leaving for 1 week was 98.02%.

Example 3 20 g of this dioxins decomposition treating agent was added to 100 g of paddy soil (PCDD / DF; 0.150 ng TEQ / g dry weight) and mixed thoroughly. After that, add water so that the content of water to the total solid content is 80%,
The mixture was stirred again and left at room temperature. The amount of dioxins (PCDD /
The results of measuring the DF value) are shown below. Immediately after addition and mixing: 0.125 ng TEQ / g dry weight, after standing for 1 week: 0.0020 ng TEQ / g dry weight, that is, the decomposition rate of dioxins after standing for 1 week was 98.4%.

Example 4 The fly ash used in Example 2 and the soil used in Example 3 were subjected to an elution test for cadmium and lead according to the elution test method (this sample is an untreated product). Further, the elution test of cadmium and lead was similarly performed on the fly ash and soil after being left for one week in Examples 2 and 3 (this sample is a treated product). The results are shown below.

[0026]

[Table 1]

The amount of cadmium and lead eluted from the treated product was below the detection limit. That is, it was revealed that the method for decomposing dioxins according to the present invention can reduce not only dioxins but also elution of cadmium and lead in fly ash and soil.

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-11-114537 (JP, A) JP-A-9-103672 (JP, A) JP-A-7-328596 (JP, A) JP-A-7- 185034 (JP, A) JP-A-6-219734 (JP, A) JP-A-5-295347 (JP, A) JP-A-2-215881 (JP, A) Special Table 2-500488 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B09B 3/00-5/00 B09C 1/00-1/10 A62D 3/00 C09K 3/00 C02F 11/00-11/20 B01J 20 / 00-20/34

Claims (7)

(57) [Claims] 1. A decomposition treating agent for dioxins, which comprises calcium oxide whose surface is oil-coated and potassium carbonate or sodium carbonate. 2. The decomposition treatment agent for dioxins according to claim 1, further comprising zeolite. 3. The content of zeolite is 1 to 50 parts by weight, and the content of potassium carbonate or sodium carbonate is 5 to 30 parts by weight with respect to 100 parts by weight of oil-coated calcium oxide on the surface. The decomposition treatment agent for dioxins according to claim 2, which is characterized in that. 4. The decomposition treatment agent for dioxins according to claim 1, wherein the surface of the calcium oxide is coated with vegetable oil. 5. A dioxin characterized in that a decomposition treatment agent containing calcium oxide, zeolite whose surface is oil coated, and potassium carbonate or sodium carbonate is added to and mixed with fly ash or soil contaminated with dioxins. Method for decomposing chemicals. 6. The initial water content in the mixture after the decomposition treatment agent is added to fly ash or soil and mixed is 30 with respect to the total solid content.
The method for decomposing dioxins according to claim 5, characterized in that the content is ˜95% by weight. 7. The amount of the decomposition treatment agent is 10 in fly ash or soil.
The decomposition treatment method of dioxins according to claim 5 or 6, wherein the amount is 10 to 50 parts by weight with respect to 0 parts by weight.