JP3326475B2 - Method for decolorizing colored wastewater containing reactive dyes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the decolorization of waste water containing reactive dyes. More specifically, the present invention relates to coagulation and decolorization of wastewater discharged from a manufacturing process of a reactive dye manufacturing plant, wastewater discharged from a process of handling reactive dye products, and wastewater discharged from a dyeing plant or the like using reactive dyes.

[0002]

2. Description of the Related Art At present, dyes are widely used in dyeing of textiles as well as in cosmetics, stationery, food, liquid crystal, electronic equipment, and color filters. Among them, reactive dyes are more water-soluble than other types of dyes, covalent bonds formed between dyes and fibers are chemically stable, dyeing fastness, especially high wet fastness, hue It has a great advantage in dyeing processing such as clearness, and is widely used at present and is expected to be a dye genus.

[0003] Generally, coloring wastewater containing a dye has an extremely high degree of coloring even though the COD and BOD values representing the environmental load are relatively small. For example, red basic dye
The coloring degree of the wastewater containing ppm is about 400 by the dilution method (representing a dilution factor at which the diluted wastewater is indistinguishable from distilled water using a fluorometer at a depth of 30 cm), and the environmental impact is reduced. Although it is small, it is a dark color, impairs aesthetics, and gives a strong sense of contamination.

In the wastewater treatment of dyeing factories, a coagulation sedimentation method using an inorganic coagulant and / or a polymer coagulant or a flotation method is often used in many cases. Japanese Patent Publication No. 55-3985 proposes to use a reducing agent such as hydrosulfite and sodium bisulfite in a coagulation decolorization using ferrous ion for a factory wastewater containing a reactive dye. I have.

[0005]

However, treatment with an inorganic flocculant and / or a polymer flocculant has a sufficient decolorizing effect on water-insoluble dyes such as disperse dyes, and is economically efficient. However, in the case of reactive dyes, the excellent properties provided for the dyeability of the fiber have an adverse effect on the decolorization of wastewater containing this dye, making decolorization difficult. . Further, a reactive dye having an increased hydrophilicity due to hydrolysis of a reactive group requires a large amount of a flocculant, and cannot be said to be an economical method including the treatment of generated sludge.

The method using ferrous ions and a reducing agent claims that the effect of the invention is that a large amount of ferrous ions to be used can be reduced. However, when ferrous ions are used, a general method is used. In addition, since the processed liquid takes on a yellow color based on iron ions, an additional advanced treatment is required and the process becomes complicated.

In view of such circumstances, the present inventors have made intensive studies on a method for decolorizing colored wastewater containing a reactive dye. As a result, a dicyandiamide-based cationic decolorizing agent, particularly pH
By using a dicyandiamide-based cation decolorizing agent having a cation exchange equivalent of about 2 to 8 meq / g in Example 4, it was found that the color was well decolorized, and the present invention was achieved.

[0008]

SUMMARY OF THE INVENTION Namely, the present invention is, sulfatoethyl sulfone or triazine anti応染fees and / or inorganic flocculating agent to the colored effluent reactive group of the reactive dye contains hydrolysed reactive dye A method for decolorizing a colored wastewater containing a reactive dye, characterized by adding a dicyandiamide-based cationic decolorizing agent and a polymer flocculant to coagulate and separate coloring components from the wastewater.

[0009] As the reactive dyes to which the present invention is _{directed, -SO 2 C 2 H 4 OSO} 3 reactive dye of sulfatoethyl sulfone having sulfatoethyl sulfone group represented by Na, the formula into the dye molecule 1

Embedded image (X ₁ is a chlorine atom, a fluorine atom, a substituted amino group, X ₂ is a chlorine atom, a methoxy group, a substituted amino group) reactive dye fees triazine having a triazine group represented by.

In addition, these reactive dyes generally undergo a hydrolysis reaction in a dyeing step, and a part of the reactive groups are decomposed. The present invention is applicable to wastewater containing a reactive dye in which the reactive group of the reactive dye is hydrolyzed.
Further, in the case of wastewater from a dyeing factory, the present invention can be applied to any of the dyeing wastewater and the dyeing wastewater for the printing method, and the mixed wastewater.

In the present invention, a dicyandiamide-based cationic decolorizing agent is used as the decolorizing agent. Cationic decolorizing agent obtained by cationization modification of polyacrylamide, cationic decolorizing agent obtained as vinyl lactam acrylamide copolymer, cationic decoloring agent obtained as cyclopolymerized diallylammonium halide, polyvinylpyridine-based cationic Dicyandiamide-based cationic decolorizers are more effective for decolorization than decolorizers, polyvinylimidazoline-based cationic decolorizers, dialkylaminoethyl acrylate or methacrylate-based cationic decolorizers, chitosan-based cationic decolorizers, and the like.

FIG. 1 shows the cation equivalent of each decolorizing agent and the p of the solution.
The relationship with H was shown. In FIG. 1, A and B are quaternary ammonium salt-type cationic decolorizing agents obtained by cationizing and modifying polyacrylic acid or polymethacrylic acid.
D and E represent dicyandiamide-based cationic decolorizing agents.
C, D and E have a cation equivalent of 5.8 at pH 4,
4.7 and 0.9. A to A of these cationic decolorizing agents
70 ppm of reactive dye (CIReactive Yellow 145: the name of the dye is indicated by Color Index Name) per E
A solution containing 7000 ppm of sodium sulfate, 3000 ppm of sodium carbonate, and 300 ppm of a nonionic activator was subjected to a decolorizing treatment. As a result, the coloring degree (dilution method) after the decolorizing treatment when using 50 ppm of the decolorizing agent at pH 4 was 500 or more. It was 500 or more, 40, 70, 250.

Accordingly, as for the dicyandiamide-based cationic decolorizing agent, the higher the cation equivalent value, the greater the decoloring performance, and the cation equivalent at pH 4 is about 2 to 8 meq /.
g, more preferably about 4 to 6 meq / g, of the bleaching agent.

The cation equivalent value is measured by titration with potassium polyvinylsulfonate solution using toluidine blue as an indicator in ordinary colloid analysis.
Can be easily implemented.

The inorganic coagulant is not particularly limited, and aluminum sulfate and polyaluminum chloride are usually used. Aluminum sulfate is preferably used in consideration of the corrosiveness of the apparatus and the sludge incineration property.

As the polymer flocculant, a nonionic or anionic polyacrylamide polymer flocculant is usually used, but a cationic polymer flocculant can also be used to increase the flocculence of floc. All of these polymer flocculants can be sufficiently achieved by commercially available polymer flocculants.

In the decolorizing treatment, usually, first, an inorganic flocculant is added to colored wastewater containing a reactive dye. The inorganic flocculant is added in an amount of about 50 to 500 ppm, preferably 100 to 200 ppm, based on the solid matter in terms of wastewater. Usually, this amount can sufficiently achieve the purpose of decolorization, but of course, more can be used when the dye concentration in the wastewater is high.

Next, the pH of the solution after adding the inorganic coagulant
Make adjustments. The pH is usually preferably about 4 to 7, but the optimum pH varies depending on the type of reactive dye contained in the wastewater. In FIG. 1, the reason why the cation equivalent of the dicyandiamide-based decolorizing agent decreases as the pH increases is not clearly understood. However, when the pH increases, the NH ₃ ⁺ group of the dicyandiamide-based decolorizing agent becomes NH ₂ group. It is considered to change to. However, in the dicyandiamide-based decolorizing agent, it is considered that the cationic group effective for decoloring is retained even though the pH may increase and the cation equivalent value may decrease. Actually, it has been recognized that under the condition of pH 11, it has the same decoloring ability as that of pH 4. Generally, a pH of about 4 to 7 is effective in many cases.

Next, a dicyandiamide-based decolorizing agent is generally added to the waste water in an amount of about 50 to 500 ppm, preferably about 100 to 300 ppm, as solids. Usually, this amount can sufficiently achieve the purpose of decolorization, but can be used more when the dye concentration in water is high. By the addition of the dicyandiamide-based cation decolorizing agent, the coloring component in the waste water usually precipitates in the form of a colloid.

Usually, a high-molecular flocculant is added at the end to floc the inorganic flocculant and the colloidal coloring component into coarse flocs. Usually, the amount of the polymer coagulant to be added is preferably about 0.5 to 5 ppm with respect to the wastewater in terms of solid matter. However, when the concentration of the coloring component is high, the amount may be increased. The generated flocs are separated by a floating method or a sedimentation method. In general, the size of the flocks is sufficiently large so that they can be easily separated.

The order of addition of the inorganic flocculant, the dicyandiamide-based cationic decolorizing agent, and the polymer flocculant is not particularly limited. Is added in consideration of the width. All of the above operations are carried out at room temperature and under stirring. The operability is extremely good because the processing time of each stage is usually completed within a few minutes. Therefore, in the processing of each stage, either a batch type or a continuous type is possible. The present invention is not particularly limited by the addition method or the treatment method.

[0022]

According to the present invention, the decolorization of the colored wastewater containing the reactive dye is achieved by the interaction of the three components, that is, the inorganic flocculant, the cationic decolorizer and the polymer flocculant. The anionic groups of the reactive dyes in the wastewater and the dicyandiamide-based cationic decolorizing agent combine to electrically neutralize and produce finely colored colloidal particles, which together with the inorganic flocculant floc are polymer flocculants. It is considered that due to the action of the above, coarse flocs are formed and aggregated and separated.

In the present invention, it is not clear why the cation equivalent of the dicyandiamide-based cationic decolorizing agent exhibits remarkable decoloring performance as compared with the polyacrylamide-based cationic decolorizing agent having the same cation equivalent. There are various reasons. It is considered that the molecular weight of the dicyandiamide-based cationic decolorizing agent obtained by condensation polymerization of dicyandiamide is considerably smaller than the molecular weight of the polyacrylamide-based cationic decolorizing agent obtained by a radical reaction. Therefore, the dicyandiamide-based cationic decolorizing agent having a smaller molecular weight has good dispersibility in a liquid, and can be smoothly contacted with a reactive dye molecule dissolved and dispersed in an aqueous solution. It is believed that neutralization is more likely to occur more efficiently.

[0024]

According to the method of the present invention, colored wastewater containing reactive dyes can be decolorized by an economical and simple operation, and a wastewater from a factory for handling reactive dyes, such as a dye manufacturing factory or a dyeing factory, can be obtained. Decolorization and purification become easier, which helps to preserve the environment and improve productivity. Further, the treated water after decolorization can be reused, and greatly contributes to resource saving and energy saving.

[0025]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The measurement of the degree of coloring of wastewater is performed by the dilution method (Pollution Control Vol.27, No.8, P.717 (199
1)). The indication of the degree of coloring of the wastewater after treatment is
◎ is 50 or less, ○ is 80 or less, Δ is 200 or less,
The crosses represent 200 or more.

Example 1 In a beaker, 200 ml of the following dyeing dyeing wastewater was placed in a beaker, and 100 pp of aluminum sulfate was added thereto while stirring.
m, and adjust the pH to 6 to 7 with caustic soda. Next, 300 ppm of various decolorizing agents and 2 ppm of Sumifloc FN-20H (manufactured by Sumitomo Chemical Co., Ltd.) (all solids concentrations) as a polymer flocculant were added, and the mixture was stirred for about 1 minute and then stopped. The supernatant was separated by filtration and the degree of coloring was measured. Table 1 shows the results.

(Dyeing Model Drainage Composition of Dyeing Method) 70 ppm of Dye (CI Reactive Yellow 145), 7000 ppm of anhydrous sodium sulfate, 3000 ppm of sodium carbonate, 300 ppm of nonionic surfactant (Squarol 400, manufactured by Kao) 300 ppm A liquid having the composition was heat-treated at 80 ° C. for 1 hour. Raw wastewater coloring: 1400

[0028]

[Table 1] Sumifloc CL-A and Sumifloc CL-B have cation equivalents at pH 4 of 4.7 and 5.8, respectively.

Example 2 Using Sumifloc CL-A and Sumifloc CL-B,
The pH after the addition of aluminum sulfate was 4, 7, and 11, and the amount of the decolorizing agent was 300 ppm, 150 ppm, and 50 ppm, and the degree of decolorization was evaluated. Table 2 shows the results. The test operation, model drainage composition, etc. were the same as in Example 1, but three types of reactive dyes were tested. The coloring degree of the raw wastewater was determined using the dyes CIReactive Yellow 145 and CIReactive Red 19
5, 140 each for CIReactive Blue 221
0, 5600, and 1400.

[0030]

[Table 2]

Example 3 A printing method was carried out in the same manner as in Example 2 except that a dyeing model wastewater was used. Table 3 shows the results. The degree of coloring of the raw wastewater was determined in Example 2.
Is the same as (Dyeing model dyeing composition for printing method) ・ Dye 70 ppm ・ Sodium alginate 200 ppm ・ Sodium bicarbonate 150 ppm ・ Sodium hexametaphosphate 30 ppm ・ Sodium m-nitrobenzenesulfonate 150 ppm ・ Nonionic surfactant (Squarol 400 manufactured by Kao) 300 As the ppm model wastewater, a liquid obtained by heat-treating a liquid having the above composition at 80 ° C. for 1 hour was used.

[0032]

[Table 3]

Example 4 A decolorization test was carried out in the same manner as in Example 2 by using actual colored wastewater from a dyeing factory mainly comprising a printing method. Table 4 shows the results. Aluminum sulfate as inorganic coagulant
00 ppm, Sumifloc FN-2 as polymer flocculant
2 ppm of 0H was added. The pH of the raw wastewater was 9.3 and the degree of coloring was 890.

[0034]

[Table 4]

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the cation equivalent of a decolorizing agent and the pH of a solution.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-72095 (JP, A) JP-A-57-171488 (JP, A) JP-A-49-20953 (JP, A) JP-A 53-72053 72369 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 1 / 58,1 / 52

Claims (3)

(57) [Claims] 1. A sulfatoethyl sulfone or tri <br/> azine anti応染fees and / or inorganic flocculating agent to the colored effluent reactive group of the reactive dye contains hydrolysed reactive dye,
A method for decolorizing colored wastewater containing a reactive dye, comprising adding a dicyandiamide-based cationic decolorizing agent and a polymer flocculant to coagulate and separate coloring components from the wastewater. 2. A cation exchange equivalent at pH 4 of 2 to 8
The method for decolorizing colored wastewater containing a reactive dye according to claim 1, wherein a dicyandiamide-based cation decolorizer having a meq / g ratio is used. 3. The method for decolorizing colored wastewater containing a reactive dye according to claim 1, wherein the inorganic coagulant is aluminum sulfate or polyaluminum chloride.