JPH05123685A - Treatment of waste water containing organic coloring material - Google Patents

Abstract

PURPOSE:To efficiently decolor waste water contg. org. coloring material without requiring the maintenance of a coloring material decomposing part of suspending the operation of an apparatus and to enable continuous economical operation by generating OH radicals in the waste water and decomposing the coloring material. CONSTITUTION:Free radicals of OH are generated in waste water contg. org. coloring material and this coloring material is decomposed. It has been made clear that this OH radical-generating system generates OH radicals according to a prescribed reaction formula and it is known that these OH radicals become active seeds. OH radicals and org. material react very rapidly with each other. The reaction mechanism of each OH radical is known as the cleavage of a double bond by the abstraction of H from an unsatd. bond or addition to a double bond or an arom. ring and OH radicals react with the chromophore of coloring materials by a similar mechanism to bring the coloring materials into oxidation decomposition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating organic dye-containing wastewater.

[0002]

2. Description of the Related Art Conventionally, activated carbon treatment, hydrogen peroxide addition treatment, ultraviolet irradiation treatment and the like have been carried out for treating organic dye-containing wastewater.

[0003]

In the above-mentioned activated carbon treatment, if the wastewater and the waste liquid are treated more than the adsorption capacity of the activated carbon, the dyes cannot be adsorbed further, and the activated carbon must be regenerated.
There is a problem in that the processing is costly and takes a long time, and the operation of the apparatus must be stopped due to the processing, and continuous processing cannot be performed. Also, in the hydrogen peroxide addition treatment and the ultraviolet irradiation treatment that do not involve shutdown, hydrogen peroxide treatment alone cannot achieve sufficient decomposition of the dye in the wastewater due to its weak oxidizing power. In the presence of a dye, ultraviolet rays are absorbed by the dye itself and do not penetrate to the inside of the liquid surface, so there was a limit to the decomposition of the dye in wastewater. In particular, almost no decomposition of humic acid, which is a kind of organic dye, is difficult to decompose.

In view of the above problems of the prior art, the present invention is a method for treating organic dye-containing wastewater capable of continuously, economically and highly efficiently decomposing organic dyes including humic acid in wastewater. Is to provide.

[0005]

The present invention provides (1) a method for treating organic dye-containing wastewater, which comprises decomposing the organic dye by producing OH radicals in the wastewater containing the organic dye. ..

(2) An organic dye-containing material characterized by decomposing the organic dye by adding hydrogen peroxide to waste water containing the organic dye and irradiating ultraviolet rays to generate OH radicals. Wastewater treatment method.

(3) Titanium dioxide powder is added to waste water containing an organic dye, and ultraviolet rays are radiated to produce O.
A method for treating organic dye-containing wastewater, which comprises generating H radicals and decomposing the organic dye.

(4) Hydrogen peroxide is added to waste water containing an organic dye, a compound containing a divalent iron ion or a compound containing a monovalent copper ion is added, and ultraviolet rays are applied to OH. A method for treating organic dye-containing wastewater, which comprises generating radicals to decompose the organic dye.
Is.

Examples of means for generating OH radicals in the present invention include adding a chelating agent such as iron, copper, ascorbic acid and EDTA to hydrogen peroxide, irradiating hydrogen peroxide with ultraviolet rays, and titanium dioxide (anatase). The mold) is irradiated with ultraviolet rays.

[0010]

In the OH radical generating system used in the present invention, it has been clarified that OH radicals are generated by the following reaction formula.

[Chemical 1]

It is known that these * OH are active species. The reaction of these radicals (free radicals) and organic substances is extremely fast. The reaction mechanism of the OH radical is known to be a cleavage reaction of a double bond by removing H of an unsaturated bond and an addition reaction to a double bond or an aromatic nucleus.
It reacts with the dye chromophore and exerts the oxidative decomposition effect of the dye. Examples of the present invention will be described below.

[0012]

【Example】

(Example 1) As an example, phenylmethane dyes Brilliant Green and Methylene Blue were selected and a decomposition test was carried out. In particular, methylene blue is a dye often used at the time of printing. As a representative example of the test results, a system in which hydrogen peroxide is irradiated with ultraviolet rays to generate OH radicals will be described below.

(1) Test Method The maximum absorption point of the absorbance was used as an index of the chromaticity of brilliant green and methylene blue. (A) Brilliant green is O. D _630nm , methylene blue is O.D. D _{660 nm} was determined as an index of chromaticity. (B) Hydrogen peroxide concentration used: 0.5 mM, ultraviolet rays: an ultraviolet irradiation device using a xenon-mercury lamp as a light source, a distance of 35 mm between the light source and the dye-containing liquid was determined as a basic condition, and a dye decomposition evaluation test was performed. .. (C) OH radicals can be detected by electron spin resonance (ES)
R) according to the spin trap method.

(2) Evaluation Test Results Hydrogen peroxide was irradiated with ultraviolet rays to examine whether or not OH radicals were generated. (A) It was determined after examining the conditions under which hydrogen peroxide was irradiated with ultraviolet rays to generate OH radicals. A typical ESR signal of OH radical is shown in FIG. (B) Hydrogen peroxide alone, ultraviolet light alone and hydrogen peroxide +
A dye decomposition / bleaching test was carried out under each condition of ultraviolet rays, and the absorbance was measured at each treatment time. The results are shown in FIGS. 2 and 3. Since hydrogen peroxide decomposes due to light and metals mixed in the container, a polyethylene container prepared and stocked was used.

FIG. 2 shows the result of decomposition of brilliant green, and UV alone has the opposite effect of increasing chromaticity. In addition, when hydrogen peroxide is used alone, the absorbance does not change and is not decomposed at all. On the other hand, under the condition of OH radical generation of hydrogen peroxide + ultraviolet rays, about 60% is decomposed in 30 minutes, and
With 0 minute treatment, about 96% decomposition is possible.

FIG. 3 shows an example of decomposition of methylene blue.
UV light alone decomposes only about 4% in 30 minutes. Further, although hydrogen peroxide alone does not decompose at all, under the condition of hydrogen peroxide + ultraviolet ray, about 65% can be decomposed by the treatment for 30 minutes and about 95% can be decomposed by the treatment for 60 minutes. (C) When ethanol, which is known as an OH radical scavenger, was added to the system of hydrogen peroxide + ultraviolet rays, the decomposition of methylene blue was almost completely suppressed, and it was confirmed that the action of this method was due to OH radicals (Fig. 3).

FIG. 4 shows the result of dye decomposition in another system in which titanium dioxide, which is an OH radical generating system, is irradiated with ultraviolet rays. Brilliant green was used as the evaluation dye.

3 in 2 ml brilliant green solution
Titanium dioxide (mg) was added, and the titanium dioxide was irradiated with ultraviolet rays, and the decomposition action was examined every reaction time. Similarly, only titanium dioxide and ultraviolet rays were tested. From FIG. 4, it can be seen that the decomposition of the dye was remarkable under the conditions of irradiation with titanium dioxide and ultraviolet rays, and a decrease in chromaticity of about 53% occurred in 20 minutes.

Example 2 As an example, humic acid was solubilized in an alkaline solution and then prepared with water to a certain chromaticity, and used in a decomposition test. As a typical example of the test results, Fe is added to hydrogen peroxide, and ultraviolet rays are irradiated to OH.
The system in which radicals are generated will be mainly described below.

(1) Test method As an index of chromaticity of humic acid, a point close to the maximum absorption of absorbance was used as an index. (A) Humic acid is O. D400 _nm was determined as an index of chromaticity. (B) Hydrogen peroxide concentration used: 2.5 mM, Fe used
SO ₄ · 7H ₂ O concentration: 10 [mu] M, UV: Xenon - ultraviolet irradiation apparatus according to a mercury lamp light source, the light source and the distance between the dye-containing solution: a 35mm determines the basic conditions and subjected to humic acid degradation evaluation test. (C) OH radicals can be detected by electron spin resonance (ES)
R) according to the spin trap method.

(2) Evaluation test results Fe was added to hydrogen peroxide and irradiated with ultraviolet rays to examine whether or not OH radicals were generated more efficiently. (A) A system in which hydrogen peroxide is irradiated with ultraviolet rays, and further Fe
The relative amount of OH radical generation in the system to which is added is compared and shown in FIG. According to this, it was confirmed that the system of hydrogen peroxide + Fe + ultraviolet efficiently generates OH radicals. (B) A humic acid decomposition / bleaching test was carried out under the conditions of hydrogen peroxide alone, ultraviolet light alone, hydrogen peroxide + ultraviolet and hydrogen peroxide + ultraviolet + Fe, and the absorbance was measured at each treatment time. The results are shown in Fig. 6. Since hydrogen peroxide decomposes due to light and metals mixed in the container, a polyethylene container prepared and stocked was used.

FIG. 6 shows the result of decomposition of humic acid. However, hydrogen peroxide alone and ultraviolet light alone do not decompose humic acid even after 120 minutes of treatment. Further, in the system of hydrogen peroxide + ultraviolet rays, about 120% of humic acid decomposition occurred only after 120 minutes. On the other hand, in the system of hydrogen peroxide + Fe + ultraviolet, the decomposition rate after 120 minutes reached 74%, and it was confirmed that the system in which the OH radical generation efficiency was increased by adding Fe exhibited high decomposition efficiency.

The present inventor has confirmed that the time required for humic acid decomposition can be shortened by increasing the concentration of hydrogen peroxide used.

Although FeSO ₄ .7H ₂ O, which is a compound containing divalent iron ions, was used in the above-mentioned examples, the same applies when compounds such as copper bromide, copper chloride, and copper rhodanide containing monovalent copper ions are used. The result was obtained.

As described above, the effect of the present invention was proved by the examples of treatment of specific organic dyes. However, the present inventor similarly decomposes many organic dyes in other OH radical generating systems. It was confirmed that decomposition of organic dyes by OH radicals was effective.

[0026]

EFFECTS OF THE INVENTION According to the present invention, by efficiently generating OH radicals, organic dyes, especially humic acid, can be decomposed and decolorized, and maintenance of the device can be stopped without requiring maintenance of the dye decomposition part. It is possible to decompose and decolorize the dye with high efficiency without the need for, and to perform the operation continuously and economically.

[Brief description of drawings]

FIG. 1 is a signal diagram of an electron spin resonance apparatus for confirming the generation of OH radicals by irradiating hydrogen peroxide with ultraviolet rays.

[Figure 2] UV irradiation, hydrogen peroxide addition and hydrogen peroxide +
Chart showing decomposition rate of Brilliant Green by UV irradiation

[Figure 3] UV irradiation, hydrogen peroxide addition and hydrogen peroxide +
Chart showing the decomposition rate of methylene blue by UV irradiation

FIG. 4 is a graph showing the decomposition rate of brilliant green by the addition of titanium dioxide, ultraviolet irradiation, and titanium dioxide + ultraviolet irradiation.

Fig. 5 Hydrogen peroxide + UV irradiation and hydrogen peroxide + Fe
+ Comparison diagram of the amount of OH radicals generated by UV irradiation.

FIG. 6 is a chart showing the decomposition rate of humic acid by hydrogen peroxide alone, ultraviolet irradiation alone, hydrogen peroxide + ultraviolet irradiation, hydrogen peroxide + Fe + ultraviolet irradiation.

Claims (4)

[Claims] 1. A method for treating organic dye-containing wastewater, which comprises generating OH radicals in wastewater containing an organic dye to decompose the organic dye. 2. An organic dye-containing wastewater, characterized in that hydrogen peroxide is added to wastewater containing an organic dye and OH radicals are generated by irradiation with ultraviolet rays to decompose the organic dye. Processing method. 3. An organic dye-containing wastewater, characterized by adding titanium dioxide powder to wastewater containing an organic dye, and irradiating ultraviolet rays to generate OH radicals to decompose the organic dye. Processing method. 4. An OH radical is obtained by adding hydrogen peroxide to waste water containing an organic dye, adding a compound containing a divalent iron ion or a compound containing a monovalent copper ion, and irradiating with ultraviolet rays. Is generated and the organic dye is decomposed, and an organic dye-containing wastewater treatment method is characterized.