JPS61204082A - Cleaning up method of water contaminated with organic halogen compound - Google Patents

Abstract

PURPOSE:To decompose the org. halogen compd. in water to an inorg. compd. efficiently by constituting a cathode of a specific metallic material and conducting electric current between electrodes. CONSTITUTION:The cathode is constituted of the material selected from the group consisting of platinum, gold, silver, nickel, lead, iron, copper and alloy consisting essentially of copper and the current is conducted between the electrodes to decompose the org. halogen compd. in the water to the inorg. compd. The voltage and current conduction quantity to be impressed between the electrodes is not particularly limited and the conduction of electricity therebetween is preferably executed usually at 0.5-1,000V voltage and 0.1-1,000A/m<2> current density. The treatment time varies with the current density and the concn. of the org. halogen compd. and is usually satisfactory with several seconds -several tens hours. The treatment to decompse the various org. halogen compds. to the inorg. compds. is possible by the above- mentioned method and is effective for decomposing particularly harmful aliphat. or arom. halogen compd. such as chloroform, trichloroethane, carbon tetrachloride and polyviphenyl chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to a method for purifying water contaminated with organic halogen compounds.

[Prior Art 1] At present, water, whether water or sewage, is contaminated to some extent with organic halogen compounds. for example,
In water supplies, water is sterilized using active chlorine compounds such as chlorine and hypochlorite. However, in the process, organic substances in the water are chlorinated by these active chlorine compounds, producing organic chlorine compounds such as triheromethane. In addition, sewage systems also receive inflows of trichrene and percrene, which are used in dry cleaning, and harmful helodene compounds produced by the incineration of municipal waste. Recent research has revealed that some of these organic halogen compounds are highly carcinogenic, which has become a serious social problem.

Currently, such organic halogen compounds in water are adsorbed and removed using adsorbents such as activated carbon, but the adsorption amount is limited and the regeneration process of the adsorbent is complicated, resulting in a low removal rate. The disadvantage is that the processing cost is extremely high.

In the process of researching photochemistry, the present inventors discovered that wavelengths of 200
We have discovered that trihalomethane in water can be oxidized and decomposed by using a combination of ~300 nz ultraviolet rays and hydrogen peroxide, or by irradiating deep ultraviolet rays with a wavelength of 200 nt or less. Although this method is an excellent purification method that can decompose trihalomethane into carbon dioxide and hydrogen chloride,
1.% is not an effective purification method for treating large amounts of water, such as drinking water or incineration waste gas cleaning water.

In addition, while researching the radiochemical reactions of various organic compound aqueous solutions, the present inventors discovered that OH produced by radiolysis of water
When radicals and hydrated electrons act on various substances, in particular, OR radicals extract hydrogen atoms from organic compounds and promote the oxidative decomposition of organic compounds, while hydrated electrons reductively decompose organic halogen compounds. It started. This radiochemical method can also be applied to purify water containing organic halogen compounds, and has the potential to become a water purification method suitable for the nuclear age, but in order to put this method into practical use, large doses of radiation are required. There are problems such as the need for a source.

[Problem to be solved by the invention 1] The present invention efficiently solves the problem of underwater fi
An object of the present invention is to provide a method for mineralizing and decomposing helodenoid compounds.

[Means for Solving the Problems 1] The present invention is based on materials selected from the group consisting of platinum, gold, silver, nickel, lead, iron, copper, and alloys containing copper as main components (hereinafter, specific metal materials). ) constitutes a cathode, and an electric current is passed between the electrodes to remove organic halogen compounds in water. ! 1
ilf! I came up with a method for purifying water contaminated with organic halogen compounds, which involves chemical decomposition or complete decomposition.

[Function] The working principle of the present invention is currently being studied in detail, but the organic halogen compound in water is reductively decomposed and mineralized on the surface of the cathode, and the decomposition rate of the organic halogen compound and the type of products are unknown. Since this differs depending on the material of the cathode material, it is presumed that the specific metal material has a catalytic effect. *It is still not clear why the above-mentioned specific metal materials exhibit excellent decomposition efficiency of organic halogen compounds, but these metal materials have a large adsorption amount of organic halogen compounds and are highly effective at reducing the transfer of charge back to organic halogen compounds. It has the property of facilitating
It is thought that such properties play an important role.

[Example] In the present invention, the cathode is composed of the above-mentioned specific metal materials, but it is sufficient that these metal materials are present at least on the surface of the cathode, and the entire cathode is not necessarily made of the above-mentioned specific metal materials. There's no need. Therefore, for example, plating the metal material on a plastic plate or gold xti
It may be coated by pasting or the like, or it may be formed by mixing and molding a metal oxide or the like with the above-mentioned specific metal material powder.

In cases where it is inconvenient for the anode to be eluted as metal ions into water by oxidation, it is preferable to use a material that elutes in a small amount, such as platinum, stainless steel, carbon, etc.

The N-electrode used in the present invention can be surface-treated by physical or chemical methods such as etching to improve power efficiency.

The voltage and amount of current applied between the electrodes is usually 0.5 to 100V, preferably 3 to 30V, but not limited to
) Voltage Te 0.1-1000A/m2, Insectophile L<Ha l~1
It is preferable to carry out at a current density of 00^/m'2.

Further, the treatment time varies depending on the current density, the concentration of the organic halogen compound, etc., but is usually several seconds to several tens of hours.

The purification method of the present invention may be a continuous method in which organic halogen compound-contaminated water is passed through a container such as a cell equipped with an electrode, or it may be a continuous method in which the electrode is immersed in the water to be treated accumulated in a wastewater reservoir or the like. A patch method may be used, or it may be used in combination with conventionally used activated carbon treatment.

When using the method of the present invention, it is possible to decompose various organic halogen compounds into minerals, but the most harmful ones are loloform, bromodichloromethane, trichloroethane, trichrene, perchlorene, chlorobenzene, carbon tetrachloride, polychlorinated biphenyls, pentachloro It is effective in decomposing aliphatic or aromatic halogen compounds such as 7-enol. These organic halogen compounds are mineralized into harmless compounds by the method of the present invention.

For example, chloroform is reductively converted to methane and hydrogen chloride, trichlene to ethane and hydrogen chloride, carbon tetrachloride to methane and hydrogen chloride, 1°1.1-trichloroethane to ethane and hydrogen chloride, and monochlorobenzene to ethane and hydrogen chloride. is converted to benzene and hydrogen chloride, and bromodichloromethane is converted to methane, hydrogen chloride, and hydrogen bromide.

When using the purification method of the present invention, a decomposition rate of about 70% or more, often in the 90% range, can be obtained, although it varies depending on the type of cathode material, the type of organic halogen compound, concentration, current density, reaction time, etc.

Next, the method of the present invention will be explained based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

Examples 1 to 8 and 1 Comparative Example Anode (electrode plate area: 52 cz2) 5OS-304 as material
Using stainless steel, the cathode (electrode plate area 52ci + 2)
Using the metal materials shown in Table 1 as materials, an aqueous chloroform solution containing chloroform at a concentration of 6 zM was placed in an electrolytic cell partitioned with a cation exchange membrane, and this was energized for 240 minutes in a closed circulation system (current density 5, Fu x io-'^
/z") L, 4329-on present') f>9.

The decomposition rate of loform was investigated. The results are shown in Table 1.

As is clear from Table 1, in Examples 1 to 8 in which the cathode was made of a specific metal material of the present invention, the decomposition rate of chloroform and the current efficiency of the product were lower than those of the comparative example (SOS-3
It is several times larger than 04).

Examples 9 to 13 The treatment was carried out in the same manner as in Example 5, except that the organic halogen compounds shown in Table 2 were used instead of chloroform as the compound to be treated, and the decomposition rate of each organic halogen compound was the same as in Example 1. I looked it up.

The results are shown in Table 2.

As is clear from Table 12, when using the method of the present invention,
It can decompose various organic halogen compounds with high efficiency, regardless of whether they are aliphatic or aromatic.

IC Lee

Claims (1)

[Claims] 1 The cathode is made of a material selected from the group consisting of platinum, gold, silver, nickel, lead, iron, copper, and alloys mainly composed of copper, and an electric current is passed between the electrodes to decompose organic halogen compounds in water into inorganic substances. A method for purifying water contaminated with organic halogen compounds.