JP2011078902A - Agent, method, and apparatus for decontaminating chemical constituting chemical weapon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agent, a method, and an apparatus for decontaminating a chemical constituting a chemical weapon. <P>SOLUTION: The agent for decontaminating a chemical includes a photocatalyst dispersed in a weak alkaline buffer solution of a pH of 10 or lower. The method of decontaminating a chemical constituting a chemical weapon employs the same. The apparatus for decontaminating a chemical constituting a chemical weapon includes a reaction chamber filled with the decontaminating agent comprising a photocatalyst dispersed in a weak alkaline buffer solution of a pH of 10 or lower, and a plurality of means of irradiating light each separated by the reaction chamber and a separation wall made from a light transmitting member, with the reaction chamber comprising an introduction port for introducing air contaminated with a chemical constituting a chemical weapon and a discharge port for discharging air clear of the chemical. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a decontamination agent that decomposes and detoxifies a chemical warfare agent used in a chemical weapon by a photocatalytic reaction with an oxide semiconductor photocatalytic material. More specifically, the present invention decomposes chemical warfare agents such as VX, sarin (GB), tabun (GA), and mustard (HD), which are highly toxic and quick-acting nerve agents, by photocatalytic reaction. The present invention also provides a decontamination agent including a photocatalyst for decontamination at a chemical warfare agent contamination site by detoxification.

  For decontamination of chemical warfare agents, a decontamination method in which a detergent is sprayed onto the chemical warfare agent is generally used. An alkaline water solvent or a substance having an oxidizing action such as sodium perchlorite sodium peroxide is a decontamination detergent. Although it is known that the alkaline aqueous solution is effective against chemical warfare agents such as GB and HD, it takes several hours to half a day to completely decompose it into a non-toxic state. I need. Further, in an alkaline aqueous solution, the hydrolysis of VX takes a long time, so it takes several tens of days until the decontamination site is restored to a safe state. In order to quickly restore the site, it is necessary to transport a large amount of alkaline aqueous solution used for decontamination to the treatment facility. Similarly, for substances having an oxidizing action such as sodium hypochlorite, treatment such as washing is required so as not to affect facilities, human bodies, and the like.

Moreover, after spraying the liquid containing a photocatalyst, the method of oxidizing a chemical warfare agent by irradiating the light beam of 220-390 nm is proposed (for example, refer patent document 1).
However, a shadow portion that does not reach light occurs, and complete decontamination is difficult, and it is necessary to finally clean the contaminated site with a detergent or warm water.
In addition, it has been proposed to introduce air to be purified into an apparatus equipped with a photocatalyst made of silica-titania composite gel after oxidative decomposition with ozone (see, for example, Patent Document 2).
However, in this method, in addition to requiring a large amount of high-concentration ozone, the use is limited to a sealed space, and it is necessary to decompose ozone after the treatment.

  In addition to being able to quickly and reliably detoxify chemical warfare agents, there is a need for an efficient decontamination method that is safe for humans, has a low environmental impact, and is easy to dispose of after decontamination.

JP-T-2004-523262 JP 2005-519721 A

  The present invention is capable of decomposing and detoxifying chemical warfare agents in order to achieve decontamination quickly and reliably at a contaminated site, and requires secondary treatment without adversely affecting the surrounding environment. It is an object to provide a chemical warfare agent decontamination agent that can dispose of waste liquid in sewage and the surrounding environment.

The present invention is a chemical warfare agent decontamination agent in which a photocatalyst is dispersed in a weak alkaline buffer having a pH of 10 or less.
The photocatalyst is the above-described decontamination agent which is any one selected from TiO2, SrTiO3, BaTiO3, and SnO2.

The photocatalyst is the above-mentioned chemical warrant remover carrying Au, Ag, Pt, Rh, RuO2, Nb, Cu, Sn, NiO, SiO2, WO3, Cu2O, RuO2, Fe2O3, CeO2.
Further, the present invention is a chemical warfare agent decontamination method for decomposing a chemical warfare agent by irradiating a decontamination agent in which a photocatalyst is dispersed in a weak alkaline buffer having a pH of 10 or less under ultraviolet irradiation.

  And a reaction chamber filled with a decontamination agent in which a photocatalyst is dispersed in a weak alkaline buffer having a pH of 10 or less, and a light irradiation means partitioned by a partition wall composed of the reaction chamber and a light transmissive member, and the reaction chamber Is a chemical warfare agent decontamination device having an air inlet polluted with chemical warfare agent and an air discharge port decontaminated with chemical warfare agent.

The chemical warfare agent decontamination agent of the present invention is composed of a photocatalyst and an alkaline buffer solution that is effective in efficiently promoting the decomposition reaction of the chemical warfare agent by the photocatalyst. Therefore, it is possible to decompose and detoxify without leaving toxic molecules in a short time. Therefore, secondary treatment such as treatment with a neutralizing agent after treatment with a chemical warfare agent decontamination agent is not required, and efficient decontamination can be performed.
Moreover, the chemical warfare agent decontamination agent of the present invention allows the decontamination detergent to be discarded in sewage after completion of decontamination, and the decontamination site can be restored quickly.

FIG. 1 is a view for explaining an example of a decontamination apparatus using the decontamination detergent of the present invention, FIG. 1 (A) is a side view, and FIG. 1 (B) is A in FIG. 1 (A). It is sectional drawing in the -A 'line. FIG. 2 is a diagram for explaining the decomposition characteristics of VX dispersed in the liquid. FIG. 3 is a diagram for explaining the relationship between the decomposition of VX dispersed in the liquid by the photocatalytic reaction and the amount of photocatalyst. FIG. 4 is a diagram for explaining the relationship between the photocatalytic degradation rate of VX and the VX concentration dependency by the chemical warfare agent removal detergent. FIG. 5 is a diagram for explaining the relationship between the decomposition of the dispersion VX in liquid by the photocatalytic reaction and the metal-supported photocatalyst-containing detergent. FIG. 6 is a diagram for explaining an example of ATR-FTIR spectroscopic measurement of the photocatalytic decomposition reaction process of VX in the photocatalyst removal detergent.

The present invention has found that in the decontamination of chemical warfare agents using a photocatalyst, the decomposition rate can be increased in an alkaline atmosphere, and the chemical warfare agents can be efficiently decomposed in a short time. It is a thing.
For example, water in which 1% by mass of titanium oxide (IV), which is a typical photocatalyst, is dispersed exhibits an acidity of about pH 4. Therefore, the decomposition rate of chemical warfare agents could not be accelerated, but the photocatalyst was dispersed. It becomes possible to accelerate the decomposition of the decontaminating agent by making it alkaline by adding an alkali, an alkali salt of a weak acid or the like into the water.
In addition, it is preferable to use a substance having a buffering action as the weak alkaline substance. By using a substance having a buffering action, a change in pH due to an acidic substance such as carbon dioxide in the atmosphere can be reduced, so that the decomposition rate of the chemical warfare agent can be promoted over a long period of time.

  In the present invention, titanium oxide (IV) particles are preferred as usable photocatalysts, but other metal oxide photocatalysts can also be used. In addition, a material in which a metal ion such as gold or silver, a metal complex, a metal, and a metal oxide are supported on these photocatalysts, and a compound that can cause a photocatalytic reaction to proceed from a semiconductor property using these composite materials may be used.

  In the case where light in the visible light region is used, a material that undergoes a photoreaction or photocatalytic reaction by absorbing visible light, such as a nitrogen atom or a sulfur atom in a part of the oxidation site of titanium (IV) oxide. , Carbon atoms or NOx coordinated or substituted titanium oxide (IV), oxide semiconductor photocatalytic materials such as SrTiO3, BaTiO3, SnO2, etc., Au, Ag, Pt, Rh, RuO2, Nb, Cu, Sn, Examples thereof include metals such as NiO, SiO2, WO3, Cu2O, RuO2, Fe2O3, and CeO2 that are supported, adsorbed, or coordinated with metal oxides or metal complexes.

Examples of the compound that is added to the decontamination agent and kept in the alkaline region of a predetermined pH include alkalis such as sodium hydroxide and potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium carbonate, sodium borate, potassium borate, etc. And salts of alkali and weak acid.
Among these, a pH of around 9 which is a weak alkali such as drinking water is preferable, and a substance that can be discharged into sewage or the like only by treatment such as dilution with water is preferable.

In addition, alkaline decontamination agents, when exposed to air or sprayed, react with acidic substances such as carbon dioxide in the air, resulting in a low pH, and the decontamination of chemical warfare agents. Therefore, it is preferable to reduce the change in pH by using a salt having a buffering action.
Specific examples include alkali salts of weak acids such as sodium borate and potassium borate.

   Moreover, the chemical warfare agent decontamination agent of the present invention can be prepared by mixing a solid mixture obtained by mixing each component with a predetermined amount of water immediately before use. Alternatively, it can be adjusted to a predetermined pH by a method of mixing each substance as a liquid substance dissolved or dispersed in water, or mixing a part of the substance as a liquid substance with another solid substance.

  In order to decontaminate chemical warfare agents with photocatalysts, it is necessary to irradiate light having a wavelength having energy absorbed by the photocatalyst such as sunlight. When titanium (IV) oxide is used as a photocatalyst, a light source containing ultraviolet light is used. Examples of the light source including ultraviolet light include various light sources such as black light, xenon lamp, mercury lamp, Hg-Xe lamp, LED, neon tube, and laser in addition to sunlight. In addition, when a light source including visible light is used, sunlight, fluorescent lamp, incandescent lamp, xenon lamp, mercury lamp, Hg-Xe lamp, LED, neon tube, laser, and the like can be given.

  It is necessary to spray the decontamination agent of the present invention in the form of a mist or foam on the contamination site, and irradiate light having a wavelength having energy absorbed by the photocatalyst as described above. In addition, decontamination is achieved by spraying the decontamination agent of the present invention and irradiating the collected liquid with light on the shaded portion that was not exposed to light. In this case, decontamination with a photocatalytic decontamination agent can be performed from a small space to a large space.

  In addition, even in small-scale contamination sites where chemical warfare agents have adhered to a small range of walls, floors, or clothing, the prescribed decontamination agent is irradiated with chemical warfare agents by spraying, etc. By doing so, decontamination can be performed.

In addition, as described above, the chemical warfare agent decontamination detergent of the present invention is not only used as a spray at a site contaminated with a chemical warfare agent, but also a decontamination method that introduces and treats contaminated site air. You may use it, filling an apparatus.
FIG. 1 is a diagram for explaining an example of a decontamination apparatus, FIG. 1 (A) is a vertical side view, and FIG. 1 (B) is an AA ′ line in FIG. 1 (A). FIG.
The decontamination apparatus 1 has a light irradiation means 7 partitioned by a transparent partition wall 5 in the reaction chamber 3, and the reaction chamber 3 is filled with the decontamination detergent 9 of the present invention.
Air contaminated with chemical warfare agent is introduced from the inlet 11 and supplied to the reaction chamber by the pump 13, and the chemical warfare agent is decomposed by irradiating light including ultraviolet rays by the light irradiation means. Air decontaminated with chemical warfare agents is discharged from the discharge port 15.

Hereinafter, the present invention will be described with reference to examples.
Example 1
Prepare a 1% by mass suspension of titanium (IV) oxide (P25 manufactured by Nippon Aerosil Co., Ltd.) as a photocatalyst, add 1 mol / L sodium hydroxide aqueous solution, and have chemical pH of 7, 8, 9, 10 An agent decontamination sample was prepared.
10 mL of each sample was placed in a 13 mL vial, and a 1 mass% VX-acetonitrile solution was added thereto so that the concentration after addition was 2 μM / L. The suspension after addition of VX was shaken and stirred for 1 minute.

The VX-containing suspension was placed on a seesaw type light irradiator and irradiated with light from one side of a vial using a black light (FED15BLB manufactured by Toshiba Lighting & Technology Corporation) while stirring left and right. At this time, the light intensity at the position of the vial was 10 mW / cm ² .

  Every 5 minutes, 1 mL of the VX-containing suspension was collected, 100 μL of Tris solution (2-amino-2hydroxymethyl-1,3-propanediol) was added to 1 mL of dichloromethane, and the mixture was shaken and stirred for 1 minute. After stirring, the dichloromethane layer was extracted and analyzed for VX at a temperature of 313 to 563 K using a DB-5 capillary column with a GC-MS analyzer (Agilent Technology 6890/5973).

The above measurement results are shown in FIG. On the other hand, in the dark place, no degradation of VX was observed even in the pH 10 sample.
When light irradiation was started, the decomposition of VX proceeded in the pH range of 7-10. The time required for decomposition to 99% or more of the initial concentration of VX was 30 minutes or more at pH 7, and 32 minutes at pH 8. On the other hand, when the pH was 9, 10, the time decreased to 13 minutes and 9 minutes, approximately 10 minutes.

  On the other hand, when only 1% by mass of titanium oxide (IV) was dispersed in water, the pH was 4.2. However, 51 minutes of light irradiation was required to decompose 99% or more of VX.

Example 2
Dissolve 12.4 g of boric acid and 14.9 g of potassium chloride in 120 mL of water, add water to a sodium borate buffer solution containing 35 mL of 0.2 N aqueous sodium hydroxide and 45 mL of water, and add sodium borate. The concentration of was diluted to 10 mM.
Next, titanium oxide (IV) was mixed to prepare suspensions with titanium oxide (IV) concentrations of 0.01 mass%, 0.1 mass%, and 1 mass%, respectively. The pH of the prepared detergent was 9.05.

A VX decomposition test was conducted in the same manner as in Example 1, and the results are shown in FIG.
FIG. 3 shows the process of decreasing VX when the amount of the photocatalyst is changed from 0.01% by mass to 1% by mass.
In the dark where no light irradiation was performed, no decomposition of VX was observed.
When light irradiation was started, VX was decomposed, and the decomposition rate was increased as the amount of photocatalyst was increased. Looking at the time when the initial concentration of VX was decomposed to 99%, the blending amount was about 20 minutes at 0.01% by weight, about 13 minutes at 0.1% by weight, and about 9 minutes at 1% by weight.
Similar to Example 1, in the case of 1% by mass, 99% or more of VX could be decomposed in 9 to 13 minutes. Similarly, even in the case of 0.1% by mass, the decomposition was possible in about 13 minutes and around 10 minutes.

Example 3
A pH 9 removal detergent containing sodium borate at a concentration of 10 mM and titanium oxide (IV) 0.1% by mass was prepared in the same manner as in Example 2, and the concentration dependency of the amount of VX degradation was the same as in Example 1. It was measured.
FIG. 4 shows the decrease rate of VX when the concentration of VX is changed to 1, 3, and 10% by mass. In the dark where no light irradiation was performed, no decomposition of VX was observed.
In addition, the VX decomposition rate by the photocatalyst decreased as the concentration of VX increased, but the time at which decomposition of 99% or more was achieved was 12 minutes (1%) 16 minutes (3%) 28 minutes ( 10%) and all decomposed in a short time.

Example 4
0.5 g of titanium (IV) oxide (P25 manufactured by Nippon Aerosil Co., Ltd.) was suspended in 25 mL of an aqueous solution adjusted to pH 9 with 1M NaOH, and the powder was dispersed by ultrasonic waves for 15 minutes.
Thereafter, silver nitrate was added so as to be 0.1 mM, and the mixture was kept in the dark for 1 hour, and then purged with nitrogen using a septum for 15 minutes. Thereafter, using a wavelength Hg-Xe lamp (SUPERCURE-203S, UV-LIGHTSOURCE, SAN-EI ELECTRIC), irradiation with light of 300 nm or more was performed for 1 hour under the condition of no aperture adjustment. Nitrogen continued to flow during the light irradiation. The powder after the light irradiation was collected by a centrifuge and washed with water three times. The washed powder was dried with a freeze dryer for 6 hours to obtain silver-supported titanium (IV) oxide.
Gold-supported titanium oxide (IV) was obtained except that an aqueous solution of chloroauric acid (HAuCl4 · 3H2O) was added instead of silver nitrate.

The decomposition characteristics of VX dispersed in the liquid were measured in the same manner as in Example 2 except that 0.1% by mass of the obtained metal-supported titanium (IV) oxide was used.
Within 6 minutes with silver-supported titanium oxide (IV) and within 10 minutes with gold-supported TiO2, VX could be decomposed by 99% or more of the initial concentration.
The result is shown in FIG.

Example 5
In order to confirm the decomposition process of VX by the detergent according to the present invention, the photocatalytic reaction process was observed by ATR-FTIR spectroscopy.
The decontamination reagent of the present invention was placed in a highly airtight ATR-FTIR cell, and 1% VX was injected therein.
In this experiment, measurement was performed by adjusting the pH to 9 using an aqueous NaOH solution having little influence on ATR measurement.
Light irradiation was performed from the upper part of the suspension surface using an ultraviolet irradiator (ZUV-C30H 360 nm, manufactured by OMRON). At this time, the light intensity on the surface of the suspension that passed through the quartz window at the top of the cell was adjusted so that the measured value by a light mirror intensity meter (UV caremate Pro manufactured by Fuji Xerox) was ² mW / cm ² .

FIG. 6 shows changes in the ATR-IR spectrum when light irradiation is started 10 minutes after dropping VX to the decontamination reagent of the present invention. It was confirmed that the ATR-IR spectrum attributed to VX changed greatly within 1 to 3 minutes of light irradiation, and the structure of VX was destroyed.
At this time, signals attributed to diisopropylamine, adsorbed isopropanol, P = O group of adsorbed VX, and other lower alcohols were observed over a wide range.

It is known that VX hydrolyzes PS and PO bonds at a ratio of about 50/50. At that time, it is known that EO2192 having high toxicity is mainly produced in the hydrolysis of PO bond as follows.

  There is almost no difference between the IR spectra of VX and EA2192, and even if EA2192 is produced by a photocatalytic reaction, the difference from VX is difficult to discern. However, since the destruction of the VX structure is confirmed in about 3 minutes from the start of light irradiation by spectrum observation, it is considered that VX is rapidly decomposed without going through EA2192.

  The chemical warfare agent removal detergent of the present invention can be disposed of directly in the surrounding environment, and does not require a secondary treatment such as addition of a neutralizing agent after the treatment of the chemical warfare agent. Decontamination can be performed, and it can be used as a chemical warfare agent decontamination detergent.

  DESCRIPTION OF SYMBOLS 1 ... Decontamination apparatus, 3 ... Reaction chamber, 5 ... Partition wall, 7 ... Light irradiation means, 9 ... Detergent, 11 ... Introduction port, 13 ... Pump, 15 ... Discharge port

Claims (5)

  A decontamination agent, wherein a photocatalyst is dispersed in a weak alkaline buffer having a pH of 10 or less.   2. The decontamination reagent according to claim 1, wherein the photocatalyst is any one selected from TiO2, SrTiO3, BaTiO3, and SnO2.   3. A photocatalyst carrying Au, Ag, Pt, Rh, RuO2, Nb, Cu, Sn, NiO, SiO2, WO3, Cu2 O, RuO2, Fe2 O3, or CeO2 Detergent for chemical warfare agent as described.   A chemical warfare agent decontamination method comprising decomposing a decontamination agent in which a photocatalyst is dispersed in a weak alkaline buffer having a pH of 10 or less under ultraviolet light irradiation.   a reaction chamber filled with a decontamination agent in which a photocatalyst is dispersed in a weak alkaline buffer solution having a pH of 10 or less, and a light irradiation means partitioned by a partition wall composed of the reaction chamber and a light transmissive member, A chemical warfare agent decontamination apparatus having an air inlet contaminated with a chemical warfare agent and an air discharge port decontaminated with a chemical warfare agent.

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