JP2006087876A - Decomposition method of organochlorine compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safe decomposition and detoxification art of organochlorine compound (PCB, dioxins and the like) fully automated and reducing the device and operation costs. <P>SOLUTION: Microbubbles (nanobubbles or the like) including hydrogen are added to and mixed with liquid containing organochlorine compound, especially PCB, dioxin or the like having strong toxicity, ultrasonic waves are emitted to the microbubbles to collapse them, the hydrogen in the air bubbles and chlorine of the organochlorine compound are reacted with and bonded to each other by the energy of the collapse to decompose and detoxify the organochlorinated compound under the normal temperature and pressure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for decomposing organochlorine compounds, and particularly provides a method for safely decomposing organochlorine compounds such as PCB and dioxin, which are difficult to decompose, at normal temperature and normal pressure.

Background technology

  Regarding PCB decomposition, alkaline catalyst decomposition method (BCD method), chemical extraction decomposition method (DMI / NaOH method) t-BuOK method, catalytic hydrodechlorination method, supercritical water oxidation method, metallic sodium method, UV irradiation / microorganism Although decomposition methods are approved, only the sodium metal method and the ultraviolet irradiation / microbial decomposition method can be decomposed at room temperature and pressure. However, the metal sodium method is not practical because it does not react unless it is completely dehydrated, and the ultraviolet irradiation / microbial decomposition method takes 10 days or more for the treatment.

Problems to be solved by the invention

Dioxin and PCB have a structure in which chlorine is bonded to a benzene nucleus, and when this chlorine is removed, it becomes a normal organic compound such as dioxydiphenyl or biphenyl. As a dechlorination method, NaOH, t-BuOK, metal Na and the like have been used. However, it is necessary to act at a high temperature other than metal Na. Supercriticality is ideal as a reaction, but has the disadvantages of high pressure hazards and expensive equipment. In addition, the metal Na method is the best in the treatment of soil contamination, but in the case of a liquid, it first needs to be dehydrated and has become a bottleneck.
In the present invention, there is provided a method for safely dechlorinating an organic chlorine compound in water or a solution at normal temperature and pressure and converting it into a harmless organic compound.

Means for solving the problem

The present inventor provides a method for safely decomposing at the normal temperature and normal pressure as described below.
(1) A microbubble containing hydrogen gas is mixed and contacted with a liquid containing an organic chlorine compound, and the mixture is irradiated with ultrasonic waves to crush the microbubble, and the hydrogen and organic chlorine in the bubble are destroyed by the energy of the crushing. A method for decomposing an organic chlorine compound, comprising reacting chlorine in the compound to decompose the organic chlorine compound.
(2) The method for decomposing an organic chlorine compound according to (1), wherein the organic chlorine compound is one or more selected from PCBs, dioxins, or VOCs such as trichlene.
(3) The method for decomposing an organochlorine compound according to (1) or (2) above, wherein an alkali metal ion is contained in a liquid containing the organochlorine compound.
(4) A metal or metal hydroxide that reacts with hydrochloric acid, such as Mg, Ca, Al, Zn, Fe, or the like, is added to a liquid containing an organic chlorine compound, as described in (1) or (2) above Decomposition method of organic chlorine compounds.

The invention's effect

According to the present invention, the following excellent effects are exhibited.
Organic chlorine compounds are generated by injecting or injecting hydrogen microbubbles (nanobubbles, etc.) into liquids containing PCBs, dioxins, etc., which are considered to be particularly degradable, and crushing the microbubbles (nanobubbles, etc.) with ultrasonic waves. Dechlorinate chlorine compounds to make them harmless. This method is an economical method in which the reaction proceeds at normal temperature and pressure, can be safely and automated, and both the equipment cost and the operation cost are low.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view of dechlorination decomposition of an organic chlorine compound of the present invention. The present invention comprises a reaction vessel provided with an ultrasonic oscillator and a microbubble (nanobubble) generator, which is connected by a pipe, and hydrogen is injected halfway while circulating the liquid with a pump. In the figure, 1 is a reaction vessel, 2 is a mixture of an organic chlorine compound, a solvent (water or organic solvent) and a neutralizing agent (alkali, for example, NaOH), 3 is an ultrasonic oscillator, 4 is a stirrer, and 5 is a baffle plate , 6 is a conduit, 7 is hydrogen, 8 is a hydrogen inlet, 9 is a pump, 10 is a microbubble (nanobubble) generator, and 11 is a microbubble jet.
Embodiments of the present invention will be described below with reference to the drawings. First, an organic chlorine compound to be treated is added to the reaction vessel 1 and, if necessary, water or an organic solvent (for example, a solvent such as IPA that dissolves the organic chlorine compound), or both, and an alkali (such as NaOH) as a neutralizing agent. The resulting mixture 2 is stirred with a stirrer 4. The ultrasonic oscillator 3 may be used for agitation. However, when the agitation is greatly performed as a whole, the mechanical agitator 4 is used, and the ultrasonic oscillator 3 is used for crushing micro vibrations and microbubbles (nano bubbles). good.

A conduit 6 is connected to the lower part of the reaction vessel 1, and a suction port 8 for hydrogen 7 is installed in the middle of the conduit. The mixed liquid 2 containing an organic chlorine compound is microbubbles (pumped by a pump 9 while sucking hydrogen bubbles). Nanobubble) is sent to the generator 10. The type of the microbubble generator is not limited, but a microbubble generator having a hydrogen bubble of 10 μm or less, preferably 1 μm or less is desirable. The hydrogen gas 7 contained in the mixed liquid 2 is brought to a state of 10 μm or less by the microbubble generator, and returns to the reaction vessel 1 from the microbubble outlet 11 through the conduit. The liquid mixture containing the hydrogen microbubbles returned to the reaction vessel 1 receives the ultrasonic waves, and the hydrogen smile bubbles are sequentially crushed. According to recent research, it is said that a high-temperature and high-pressure state of 5000 ° C. or more and 1000 atm or more appears in an instant of microseconds when microbubbles are collapsed. (Asahi Shimbun, March 6, 2004, page 5) Of course, this is a micro reaction, so the temperature rises a little overall, but it remains at room temperature and normal pressure, and no significant change is observed. (See http://www.aist.go.jp/aist j / press release / pr2004 / pr200440315 / pr200440315.html ) The present invention replaces air or oxygen bubbles with hydrogen and replaces the collapse of hydrogen bubbles with PCB, dioxin Applied to the dechlorination decomposition of

  The hydrogen microbubbles are crushed by repeated expansion and contraction under ultrasonic stimulation. At this time, ultrasonic waves may be irradiated intermittently, or radiation, electromagnetic waves, electric fields, magnetic fields, etc. may be used. At the time of this collapse, hydrogen receives a large amount of energy (as described above, it is a moment of microseconds, but it is 5000 ° C. or more at 1000 atmospheres), reacts with nearby organic chlorine compounds, combines with chlorine to form hydrogen chloride, Hydrogenate chlorine compounds. For example, the toxicity of PCB and dioxin decreases rapidly when dechlorinated or hydrogenated. Although it is an ultra-high temperature and ultra-high pressure reaction in such a micro state, there is no problem in the safety of the reaction as long as the temperature rises slightly even if the reaction is repeated because of the time of microseconds.

  In addition, since the exhaust gas has a residual amount of hydrogen, the produced hydrogen chloride is neutralized with alkali, so there is no problem with exhaust gas. Further, since the waste liquid is mixed with an organic compound from which chlorine has been removed, an added organic solvent, neutralized NaCl, and the like, the organic substance is recovered by distillation, and the remainder is alkaline, so it is used as an alkali neutralizing liquid. In the present invention, this dechlorination and hydrogenation reaction are automatically and continuously carried out, so it is relatively easy to make them below the regulation value. The baffle plate 5 is for preventing the minute hydrogen bubbles coming out from the minute bubble outlet 11 from coming out of the conduit 6 immediately without being crushed.

In this method, a chlorine ion meter may be used to know the progress of the reaction. Since chlorine is an organic chlorine compound at first, the chlorine ion is zero. However, as the reaction progresses, it changes to HCl or NaCl, and is sensitive to the chlorine ion meter, so the value of chlorine ion is a measure of the progress of the reaction. (In fact, analysis is also necessary)
At the time of neutralization, the hydrochloric acid may be neutralized with a metal such as aluminum, iron, zinc, magnesium or the hydroxide thereof instead of the alkali. However, since there is a difference in the solubility of the product in this case, management with a chlorine ion meter is not appropriate.

  In general, PCBs and dioxins are almost dechlorinated even if an alkali is used if the temperature is set to 300 to 400 ° C. However, local residents are worried about accidents such as gas leaks or machine breakage at high temperatures. According to the method of the present invention, the reaction proceeds at a completely normal temperature and normal pressure. Therefore, even if the reaction vessel breaks due to an earthquake or the like, it is sufficiently safe just to make a receptacle like a liquid reservoir. Moreover, the main equipment is an ultrasonic oscillator and a microbubble generator, which does not incur fuel costs because it reacts at room temperature, and labor can be reduced by automation, resulting in lower costs.

Explanatory drawing of dechlorination decomposition of an organic chlorine compound.

Explanation of symbols

1: Reaction vessel 2: Mixture of organic chlorine compound, solvent (organic solvent such as water or IPA) and neutralizing agent (alkali, NaOH, etc.) 3: Ultrasonic oscillator 4: Stirrer 5: Baffle plate 6: Conduit 7: Hydrogen 8: Hydrogen inlet 9: Pump 10: Microbubble generator 11: Microbubble outlet 12: Drain cock

Claims (4)

Mixing and contacting microbubbles containing hydrogen gas to a liquid containing an organic chlorine compound, irradiating the mixture with ultrasonic waves, crushing the microbubbles, and using the energy of the collapse, the hydrogen in the bubbles and the organochlorine compound A method for decomposing an organochlorine compound, comprising reacting chlorine in a reaction to decompose the organochlorine compound. 2. The method for decomposing an organic chlorine compound according to claim 1, wherein the organic chlorine compound is one or more selected from PCBs, dioxins, or VOCs such as trichlene. 3. The method for decomposing an organic chlorine compound according to claim 1, wherein an alkali metal ion is contained in the liquid containing the organic chlorine compound. 3. The method for decomposing an organochlorine compound according to claim 1, wherein a metal or metal hydroxide that reacts with hydrochloric acid such as Mg, Ca, Al, Zn, Fe, or the like is added to the liquid containing the organochlorine compound. .

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