JP2008245911A - Detoxification method of organic halogen compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detoxification method of organic halogen compound capable of decomposing it under a relatively mild operation conditions by a small number of processes at a high decomposition rate, and being applicable to organic halogen compounds of a wide form using a simple-structured and inexpensive semi-sealed type detoxification device. <P>SOLUTION: This detoxification method is characterized in that organic halogen compound adsorbed or stuck to a solid phase or a semi-solid phase is put in the semi-sealed container under a mild condition (heating to 260°C or less under normal pressure) and agitatingly mixes medical agent acting as alkaline chemical and dehydrating agent in a state of passing a small amount of inert gas (the inert gas is defined as N2, argon, helium gas and the like) therein. This method can thus dehalogenate 95% or more organic halogen compound absorbed or stuck to the solid phase or the semi-solid phase under the mild condition by the simple treatment processes at a low cost. Alternatively, if an impact energy by an impact body such as a hard ball is applied thereto in the agitating mixture, the solid substance or the semi-solid substance can be sufficiently pulverized and further dehalogenated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for detoxifying organic halogen compounds represented by dioxys and polychlorinated biphenyls (PCB).

  As is well known, organic halogen compounds represented by dioxys and polychlorinated biphenyls (PCB) are thermally stable and hardly decomposed. However, since organic halogen compounds have an adverse effect on the environment, it is necessary to make them harmless, and many harmless technologies have been disclosed so far.

  Examples of the detoxification technology include (1) incineration method, (2) plasma decomposition method, (3) reductive pyrolysis method, (4) reduced pressure reduction heat treatment method, (5) hydrothermal decomposition method, and (6) supercritical hydrolytic decomposition. Method (7) Infrared heating desorption / incineration method (8) Alkaline catalytic decomposition method (9) Dehalogenation method by catalytic hydrogenation (10) Mechanochemical method (11) Metal sodium dechlorination method (12) Metal sodium dispersion Body method (13) Metal sodium dispersion oil dechlorination method.

  (1) The incineration method is a method in which an organic halogen compound is decomposed by a high-temperature oxidation reaction at a temperature of about 800 to 1800 ° C. in air. (2) The plasma decomposition method is a method in which an organic halogen compound is thermally decomposed at a high temperature of 1300 ° C. or higher in a plasma arc furnace or the like. The (3) reductive pyrolysis method is a method of dechlorination by heating at about 400 to 500 ° C. in a nitrogen atmosphere or a hydrogen atmosphere.

  (4) The reduced pressure reduction heat treatment method is a method of dechlorination by heating at a temperature of 600 ° C. or higher in a reduced pressure, low concentration oxygen atmosphere. The (5) hydrothermal decomposition method is a method in which an organic halogen compound is oxidized and decomposed with high-temperature and high-pressure steam. (6) The supercritical hydrolytic decomposition method is a method of oxidative decomposition using high-temperature and high-pressure supercritical water. (7) The infrared heating desorption / incineration method is a method in which an organic chlorine compound desorbed from a solid phase such as soil is burned and oxidized and decomposed by infrared heating at about 500 to 1000 ° C.

  (8) The alkali catalyst decomposition method is a method in which a catalyst and an alkaline aqueous solution or a catalyst and an alkali salt of an alcohol are added, followed by heating at 200 to 350 ° C. for dechlorination. (9) The dehalogenation method by catalytic hydrogenation is a method for dehalogenation by introducing hydrogen gas and catalytic hydrogenation in the presence of a noble metal catalyst. (10) The mechanochemical method is a method in which after adding calcium oxide and a hydrogen donor, mechanical energy is applied to the reaction product by an unheated pulverization operation in the presence of argon to dechlorinate the organic halogen compound.

  (11) Metal sodium dechlorination method, (12) Metal sodium dispersion method and (13) Metal sodium dispersion oil dechlorination method all add metal sodium finely dispersed in mineral oil, nitrogen atmosphere It is the method of heating at about 70-150 degreeC below and dechlorinating.

  The detoxification methods (1) to (8) described above are (b) severe operating conditions such as being necessary to be performed under high temperature or high temperature / high pressure conditions, and (b) requiring a large-scale apparatus. ) Problems have been pointed out such as complicated operation and (d) requiring expensive chemicals such as alkaline chemicals. Further, the detoxification treatment method (10) has the advantage that it can be treated at a normal temperature with an inexpensive alkaline agent, but has the disadvantage that the detoxification treatment requires a long time of about 3 days.

  On the other hand, the treatment methods (8), (9) and (11) to (13) are directly applied to the detoxification treatment of organic halogen compounds contained in solid phase or semi-solid phase such as soil and sediment. It is impossible. In any of these methods, it is necessary to separate organic pollutants from solid or semi-solid phase such as soil and sediment using solvent shaking, decompression / heating, and high temperature heating. is there.

  For example, as a specific example thereof, a method is disclosed in which an extraction step for transferring an organochlorine compound into an organic solvent from an object to be treated containing the organochlorine compound is performed, and the extract is reduced by a reduction catalyst. The target organic chlorine compound is preferably an aliphatic chlorine compound, and examples of aromatic organic chlorine compounds are not described (see, for example, Patent Document 1).

  The inventor discloses a technique for stirring and mixing reaction accelerators such as dixins, alcohols, metallic calcium and organic acids to render the dixins harmless, and has obtained patents (for example, Patent Document 2, (See Patent Document 3 and Patent Document 4). Furthermore, Ukisu et al. Discloses a technique for detoxifying solution dioxins using isopropyl alcohol and sodium hydroxide in the presence of a palladium catalyst (see Non-Patent Document 1).

JP 2004-243255 A JP 2004-65729 A Japanese Patent No. 3533389 Japanese Patent No. 3785556 Appl. Catal. A: General, 271, 165-170, 2004

  The incineration method, plasma decomposition method, supercritical hydroxylation decomposition method, and infrared heat desorption / incineration method are techniques that can quickly render an organic chlorine compound in a solid phase or semi-solid phase harmless. However, both of them require expensive and complicated devices, and in order to perform processing under high-temperature conditions or high-temperature / high-pressure conditions, a large amount of expenses are required for maintenance costs, repair costs, and the like. In addition, there are disadvantages such as explosion due to high-temperature treatment or high-temperature / high-pressure treatment, and a large amount of exhaust gas released into the atmosphere. Furthermore, an expensive monitoring device is required for the continuous monitoring system for exhaust gas.

  On the other hand, the reductive pyrolysis method and the reduced pressure reduction heat treatment method are also widely used for the detoxification treatment of organochlorine compounds contained in the solid phase or semi-solid phase. However, these methods require heat treatment at 400 ° C. or higher, and there is a disadvantage in that the energy maintenance cost is high. As described above, the mechanochemical method is an excellent treatment method due to the use of a low-cost alkaline treatment agent and hydrogen union, non-heating and sealing treatment, but it has the disadvantage of requiring a long time for detoxification treatment. There is.

  On the other hand, hydrothermal decomposition method, alkali catalyst decomposition method, dehalogenation method by catalytic hydrogenation, metal sodium dechlorination method, metal sodium dispersion method and metal sodium dispersion oil dechlorination method are all solid phase There is a drawback that it cannot be directly applied as a detoxification treatment method for organochlorine compounds contained in the solid phase.

  Similarly, in the technique described in Patent Document 1, the organochlorine compound is transferred into an organic solvent, thereby concentrating the organochlorine compound and reducing the concentrate using a catalyst to increase the decomposition rate. However, a process for transferring the organic chlorine compound into the organic solvent and a liquid processing process for separating and removing unnecessary decomposition products after the reduction treatment are required, and a number of complicated processing steps are required. It becomes.

  In addition, the technique described in Patent Document 2 is a technique that is useful and a technique for detoxifying dixins by stirring and mixing reaction accelerators such as dixins, alcohols, metallic calcium, and organic acids, and has a wide range of organic halogen compounds. However, the development of a technology capable of detoxifying organic halogen compounds more efficiently than the present technology is awaited.

  The technique of Ukisu et al. Is a technique for detoxifying solution-type dioxins, but a technique for detoxifying dioxins adsorbed on a solid phase is not disclosed. About this point, the technique of patent document 1 and patent document 2 is also the same.

  Needless to say, in order to detoxify an organic halogen compound, it is desirable to use a technique that has a small number of steps and can be detoxified under mild conditions. It is also desirable that the device for detoxifying the organic halogen compound is a device that can be manufactured at low cost with a simple configuration.

  Furthermore, development of a detoxifying method and a detoxifying device applicable to a wide variety of organic halogen compounds is awaited. In particular, the development of a technique for reducing the decomposition temperature using an inexpensive drug and detoxifying the organic halogen compound adsorbed on the solid phase in a form close to hermeticity under low energy input conditions is eagerly desired.

  The object of the present invention is that it can be decomposed under relatively mild operating conditions with few steps, has a high decomposition rate, is simple in structure, is inexpensive, and uses a semi-enclosed detoxification treatment device, and has a wide range of forms. It is an object of the present invention to provide a detoxification method for an organic halogen compound applicable to the organic halogen compound.

  In order to solve the above-mentioned problems, the present invention puts an organic halogen compound adsorbed or attached to a solid phase or a semi-solid phase into a semi-sealed container, and is under mild conditions (heating at about 260 ° C. or lower, normal pressure). In addition, a dehalogenation treatment is performed by stirring and mixing an alkali agent and a chemical agent acting as a dehydrating agent in a state in which a trace amount of inert gas (inert gas means N2, argon, helium gas, etc.) is allowed to flow. The processing method to perform is provided.

  Further, if an impact by pulverization or hard balls or the like is applied at the time of stirring and mixing, the dehalogenation process further proceeds by heating and miniaturization due to collision.

  As explained above, it is possible to dehalogenate 95% or more of organic halogen compounds adsorbed or adhering to a solid phase or semi-solid phase under mild conditions with simple processing steps and with an inexpensive apparatus. Become. In addition, if impact energy by an impact body such as a hard ball is applied during the stirring and mixing, the solid material or the semi-solid material can be sufficiently pulverized and further dehalogenated.

  A method for treating an organic halogen compound adsorbed or adhering to a solid phase or semi-solid phase using the present invention has the following form.

  (1) Contaminated soil and ash containing organic halogen compounds and low-priced agents that act as alkaline agents and dehydrating agents (for example, calcium oxide (CaO), calcium oxide + a small amount of metal Ca) can be stirred and mixed in a predetermined amount. Place in a semi-closed container.

(2) While flowing a small amount of inert gas (for example, N _2, argon, helium gas, etc.), stirring and mixing (or crushing, with impact) of the processed material and chemicals are performed, and at the same time gentle heating at about 260 ° C. I do.

(3) After the treatment for a certain time, it is cooled and taken out from the container, and the treatment is completed.
It is important that the organohalogen compound and the chemical come into direct contact with each other during processing, and it is important to provide energy that promotes the dechlorination reaction. To this end, impacts that cause sufficient pulverization and dechlorination of the treated product The supply of impact energy by the body is effective.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an example in which this processing method is implemented.

  A sample was prepared by adding 20% quick lime (CaO) to PCB-contaminated soil (water content: 3.2% WB) and mixing with a mixer for 30 minutes. About 1 g of the sample and 0.01 g of metallic Ca were reacted. The container 1 (inner diameter 2.3 cm, length 15 cm, made of SUS) was charged.

Next, after filling with N ₂ gas so as to be 0.1 MPa and sealing, heating is performed using a ribbon heater 6 under the conditions shown in Table 1, and the stirrer 5 in the reaction vessel 1 is set to 400 rpm using the stirrer 3. The mixture was heated at 260 ° C. for 2 hours while mixing the sample while rotating at a speed of 2 ° C. to perform detoxification treatment including dechlorination. After cooling, the amount of PCB remaining was measured using an ECD-GC chromatogram. The results are shown in Table 2.

An embodiment of the present invention will be described.

Explanation of symbols

1 Reaction vessel 2 Sample 3 Stirrus 4 Thermometer (thermocouple)
5 Stirrer 6 Ribbon heater 7 Heat insulation

Claims (6)

  The heat of hydration generated in the dehydration process is dehalogenated by adding and mixing organic halogen compounds adsorbed or adhering to the solid phase or semi-solid phase under heating in the presence of an agent that acts as an alkaline agent and dehydrating agent. A process for dehalogenating the organic halogen compound as auxiliary heat for promoting the hydrogenation reaction, and then adding, mixing and heating the alkali metal or / and alkaline earth metal in the system, A method for detoxifying an organic halogen compound, which is combined with a process for dehalogenating a compound more efficiently.   2. The organohalogen compound according to claim 1, wherein the dehalogenation treatment is performed in a temperature range of 260 ° C. or lower by constantly supplying an inert gas into the reaction system or filling an excess amount. Detoxification treatment method.   The alkali agent and the agent acting as a dehydrating agent are accelerators for dehalogenation treatment, and refer to alkaline earth metal oxides dehydrated from metal hydrate, and the dehalogenation treatment is performed at 260 ° C. The method for detoxifying an organic halogen compound according to claim 1 or 2, wherein the method is performed as follows.   The agent acting as the alkali agent and the dehydrating agent is a agent capable of reducing the water content in the system, and at the same time, the dehydrated water is captured as bound water constituting the alkaline earth metal hydrate. The method for detoxifying an organohalogen compound according to claim 1 or 2, wherein the alkali agent can be used.   An impact-type agitation and pulverization apparatus capable of supplying impact energy by an impactor capable of refining the solid matter in the reaction system and promoting dehalogenation reaction is used. Or the detoxification process of the organohalogen compound of 4. An impact type stirring device capable of supplying impact energy from an impact body capable of promoting dehalogenation reaction while stirring and mixing all powders in the reaction system is used. Or the detoxification process of the organohalogen compound of 4.

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