JPS6011158B2 - Method for reusing hexavalent chromium in dyeing wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention deals with wastewater containing hexavalent chromium (hereinafter simply referred to as acid dyeing wastewater) discharged from a textile dyeing process, particularly a textile dyeing process using acidic soot dye.

This invention relates to a method of recovering hexavalent chromium from ) and reusing it as a chromium treatment agent for dyeing with acidic soot dyes. As a matter of fact, textile dyeing wastewater using acidic soot dyes usually contains a number I.
Since it contains hexavalent chromium up to the Q-leg, it cannot be directly discharged as wastewater, and various methods have been proposed to remove it.

For example, methods are being explored in which wastewater containing hexavalent chromium is reduced under acidic sulfuric acid using sodium sulfite or ferrous sulfate, and then coagulated, or electrolytically reduced and then coagulated. These methods generate a large amount of sludge containing harmful hexavalent chromium, and there are many problems with this disposal, such as the risk of secondary pollution if the sludge is sent to a landfill, etc. Not only that, but it was extremely uneconomical.

For this reason, recovery and reuse using ion-exchange resins may be considered, but acid dye wastewater contains residual dyes and organic acids, so its COD is quite high, so conventional ion-exchange resins cannot handle hexavalent COD.

Not only does it have a low amount of chromium adsorption, but it also adsorbs dyes and organic acids, so the molten solution after alkaline desorption is very dirty and cannot be reused as a chroming agent when dyeing acidic dyes. Not only that, but with conventional ion exchange resins, the comb adsorption and exchange capacity decreased markedly with each ion exchange-desorption cycle, making them impractical. In the past, the ionized sardine resin method was not generally adopted, and reduction treatment had to be carried out.In view of the above-mentioned circumstances, the present inventors have conducted extensive research and examination, and have found that specific bone The present invention has been completed based on the discovery that the object can be achieved very conveniently by using an ion exchange resin having a nuclear structure.

That is, the present invention provides a method for recovering hexavalent chromium from wastewater containing hexavalent chromium discharged from a textile dyeing process using acidic mordant dyes and reusing it for dyeing with acidic mordant dyes. A step of adsorbing hexavalent chromium from the hexavalent chromium-containing wastewater using a salt type weak base deducting ion exchanger resin having a highly crosslinked structure in the main chain or side chain (b' adsorbing the hexavalent chromium adsorption resin) Step 'c' of obtaining a hexavalent chromium-containing melting solution by desorption treatment with an alkaline aqueous solution
A method for reusing hexavalent chromium in dyeing wastewater using an acidic soot dye, the method comprising the step of reusing the hexavalent chromium eluent as a chromium treatment agent during dyeing with an acidic dye. be.

The most significant feature of the present invention is that it is suitable for the treatment of '1' acid and soot dyeing wastewater.Highly cross-linked salt-type weakly basic anion exchange resin (hereinafter abbreviated as pyridine resin) having a pyridine bone structure in its main chain or side chain .

), and ■ The recovered hexavalent chromium-containing eluent is used as a chromium treatment agent (chromium raw material) during dyeing with acidic mordant dyes. In addition to reusing chromium as a chromium raw material, we have developed a substantially completely closed system as a treatment method for wastewater containing hexavalent chromium.

According to the method of the present invention, hexavalent chromium is advantageously recovered from acid dyeing wastewater, and by using the recovered hexavalent chromium-containing syneresis liquid for chromium treatment for dyeing with acidic mordant dyes, A dyed product can be obtained that is comparable to dyed products using chromium compounds, that is, excellent in hue, color fastness, etc.

Therefore, the industrial and economic significance of the present invention is extremely large, and its effects are immeasurable. The pyridine resin used in the present invention is, for example, Samurai Kaisho 51-11
As described in the 4-Makukei publication, pinylpyridines such as 4-pinylpyridine, 2-vinylpyridine, 4-vinyl-2-methylpyridine, and vinylisoquinoline are used as monomers, and divinylbenzene and divinylbenzene are used as crosslinking agents.
It is easily produced by using divinyl phthalate, ethylene glycol diacrylate, etc., alone or by copolymerizing these.

In the meantime, the resin is treated with hydrochloric acid or sulfuric acid or the like to be used in the salt form, and the sulfate form is particularly preferably used. Specifically, the pyridine resin of the present invention is Sumichelate CR.
-2 (product name of Sumitomo Chemical Co., Ltd.). As the pyridine resin used in the present invention, so-called gel type resins and porous (macroporous type) resins are used, and porous resins are preferably used.

In the present invention, sodium hydroxide, potassium hydroxide, etc. are preferably used as the alkaline aqueous solution used for the desorption treatment of hexavalent chromium adsorbed on the pyridine resin. The closed system of the present invention will be explained in detail below.

In the method of the present invention, before passing the acid and soot dyeing wastewater through the pyridine resin, it is preferable that the raw wastewater to be treated is first subjected to removal of suspended substances of fibers such as wool, and pH adjustment.

The feed is usually adjusted to have a pH in the range of 2 to 7. Since the amount of hexavalent chromium adsorbed by the pyridine resin used in the present invention is generally more affected by pH than commercially available amine resins, it is particularly desirable to set the axis to a range of 2 to 4. The acid soot dyeing wastewater subjected to the above treatment has a COD of 10
It is an opaque liquid with a scale of 0 to 100 degrees and contains a large amount of residual dye. Generally commercially available anion resins have primary to quaternary amine groups as exchange groups and have a crosslinking degree of around 8%, but when acid and soot dyeing wastewater is passed through these resins, the dye itself A large amount of hexavalent chromium is adsorbed on the resin, which reduces the amount of hexavalent chromium adsorbed, making it extremely difficult to regenerate. However, the pyridine resin used in the present invention not only has an exchange group that is resistant to chromic acid oxidation and has excellent heat resistance, but also has a very fine network structure (micropores) inside the resin, which makes it difficult to compare with commercially available anionic resins. As a result, the amount of dye adsorbed is drastically reduced, and depending on the type of dye, it may not be adsorbed at all. In this way, it is possible to contact the pyridine resin as raw water through a simple furnace filtration treatment and pH adjustment without performing decolorization treatment, COD removal treatment, etc., which are considered necessary from the general concept of ion exchange resin. This is also one of the major features of the present invention. Acid soot dyeing wastewater usually contains up to several IQ levels of hexavalent chromium, but when this raw wastewater is brought into contact with pyridine resin, it can be treated using a general liquid flow operation method to remove hexavalent chromium from the raw wastewater. Adsorbs a constant amount of hexavalent chromium without being affected by chromium concentration.

The hexavalent chromium adsorption capacity of this pyridine resin is 60 to 80 times of hexavalent chromium per night of the swelling resin. The pyridine resin that has adsorbed hexavalent chromium is usually desorbed using an alkaline aqueous solution such as sodium hydroxide.

By the way, hexavalent chloride in the ion exchange method.

The amount of desorbing regenerant must be considered in order to operate the recycle economically. In the case of acid and soot dyeing wastewater, depending on the type of dye, the dye may be slightly adsorbed to the pyridine resin or not at all, and the regeneration level is slightly affected by this, but the hexavalent chromium adsorbed to the resin By using an excess of alkali over the theoretical equivalent, typically about 50%, a regeneration efficiency of 100% is achieved.

The pyridine resin from which the hexavalent chromium has been desorbed is then washed with several times the amount of water to the resin in a known manner, and then converted into sulfate form using an amount of sulfuric acid equivalent to the total exchange capacity of the pyridine resin. Finally, the resin is washed with water 2 to 4 times the amount of resin, and used for the next cycle of adsorption of hexavalent chromium.

The amount of sulfuric acid used here is determined by measuring the total exchange capacity of the pyridine resin with sulfuric acid, which adsorbs 3 equivalents of sulfuric acid per 1 swelled resin. It is preferable to use sulfuric acid. The alkaline desorption solution containing a high concentration of hexavalent chromium has a very low dye content compared to commercially available resin desorption solutions. Although it can be used as a treatment agent, it can be easily decolored by post-treatment such as activated carbon treatment if necessary, and thus can also be used in medium color dyeing processes.

This is also one of the advantages of the present invention, which has been dramatically improved by using pyridine resin. Hereinafter, the present invention will be explained in more detail with reference to Reference Examples, Examples, and Comparative Examples, but it goes without saying that the present invention is not limited thereto.

Reference example 1 (Synthesis of pyridine resin) Kagi Azusa, 2 4 liters of water in a separable flask equipped with a condenser
48 evenings, salt 186 evenings, NaN0 2.3 evenings, hydroxyethyl cellulose 3.4 evenings, divinylbenzene 109 evenings
Then, add 47 liters of isooctane, 163 liters of 4-pinylpyridine and 1.6 liters of penzoyl peroxide, and gradually heat to 80 ml for 3 hours, then 95 qo.
I worshiped her for 5 hours.

After cooling, filtration, methanol washing and wound washing were repeated several times to obtain white opaque granular material 700'. A sulfate type resin (pyridine resin) was obtained using sulfuric acid in an amount equivalent to the pure exchange capacity of the resin. Example 1 (1st cycle) 10. as hexavalent chromium. Saddle soot dyeing wastewater containing anchor wind ~
After filtering to remove hair and the like, sulfuric acid was added to adjust the pH to 2.5.

Pyridine resin 10 obtained in Reference Example 1 was added to the acid dyeing wastewater subjected to the above treatment for 2 hours per hour (SV = 2 plates - 1).
The liquid was passed at a rate of .

After passing the solution for 302 hours (processed water amount: 604 hours), 6% of the treated water was
The valent chromium concentration is 0. The fluid flow was stopped because the temperature reached the string level or higher.

The flow point is 0.0 as hexavalent chromium. & When sailed, the through-flow exchange capacity of pyridine resin per night is 62.7 terasCr6
It was ten. For resin desorption and regeneration, use 4% NaOH aqueous solution 80
0 ['Water wash 600', 5% day 2S04 aqueous solution 300'
[, 500 ml of water washing was performed in the above order, all with downflow liquid passing with SV = 1 value - 1. The concentration of hexavalent chromium in the eluent (800 M of 4% NaOH aqueous solution and 600 M of washing water) was 1.4 mm. From this, it was found that the regeneration efficiency was approximately 100%. Example 2 (2nd cycle to 6th cycle) The pyridine resin regenerated into S04 type in the first cycle in Example 1 was backwashed using approximately 100% water and then used for hexavalent chromium adsorption in the next cycle. Served.

This operation was repeated. In the second to sixth cycles, the alkaline desorbent was added to 8% NaOH aqueous solution 400%
The liquid passage conditions were the same as in the first cycle except that ' was replaced with '.

In each cycle, the flow point is set to 0. Table 1 shows the through-flow exchange capacity per 1 day of pyridine resin in the case of 1 hour of pyridine resin. Table 1 Comparative example of flow-through exchange capacity of hexavalent chromium 1 (1st cycle) In place of the pyridiso resin used in Example 1, a commercially available weakly basic anion exchange resin was used as Leverchit Mm-64 (manufactured by Bayer AG) S04 type. 100' was used.

The raw wastewater used and the flow conditions were the same as in Example 1. After passing the liquid for 14 hours (treatment water amount: 296 hours), the concentration of hexavalent chromium in the treated water was 0. The flow of fluid was stopped because the wind was above the auxiliary level.

The through-flow exchange capacity of hexavalent chromium per Leverchit M-641 (through-flow point 0.kari as Cr60) is 30.6 taa
It was sCr60. Regeneration of the resin was carried out in the following order: 4% NaOH aqueous solution 1 time, water rinsing 600 times, 5% ratio S04 aqueous solution 300 times, and water rinsing 500 times, in the order of down flow at SV = 10 h-1. The concentration of hexavalent chromium in the eluent (4% NaOH aqueous solution overnight and 600 ml of water washing ()1.6) was on the 192 side. As shown in Reference Example 2, this eluent was very dirty compared to the eluent of the pyridine resin of the present invention because the resin also adsorbed the dye at the same time. (2nd cycle to 4th cycle) The resin regenerated into S04 type in the first cycle has a water content of approximately 100%.
After being used and backwashed, it was used for the next cycle of hexavalent chromium adsorption.

The same raw water as in Example 1 was used for the second to fourth cycles, and the liquid passage conditions and desorption/regeneration conditions were the same as in the first cycle.

Table 2 shows the through-flow exchange capacity per lever chit MP-641Z when the through-flow point is set to 0.5 legs asCr60 in each cycle. 1st cycle flow exchange capacity 30
．． The reason why the through-flow exchange capacity after the second cycle decreased during the second cycle compared to 6 ta asC is considered to be because the mordant dye adsorbed to the resin and blocked the pores. Both eluents were much dirtier than the pyridine resin eluent due to the dye. Table 2 Reference Example 2 of Through-Flow Exchange Capacity of Hexavalent Chromium (Adsorption Experiment for Media Dye) An adsorption experiment for acidic soot beam dye was conducted using pyridine resin and a commercially available resin (Leverchitz MP-64).

About 9 types of soot dyes, 20 treatments for each dye and 100 Feng Shui solutions
A kite was placed in a 300° Erlenmeyer flask, 1 ton of salt-type pyridine resin was added, and the flask was immediately shaken at 3000° C. for 1 hour. The same test was conducted for Levertit MP-64 type S04. After shaking the face, the resin was washed, the pH of the solution was adjusted to 7, and the concentration of the dye remaining in the solution was measured at the maximum absorption wavelength of each chromium dye. The results are shown in Table 3, and the adsorption degree of chromium dye for pyridine resin is higher than Leverchit MP-6.
It can be seen that this is very small compared to 4.

Table 3 Chromium dye adsorption experiment The numbers in Table 3 indicate the dye concentration remaining in the liquid after the adsorption experiment.

Example 3 A wool fabric (surge) was dyed according to the following method using a conventional dyeing method.

Note that the amount of each compound used is a value relative to the amount of the dyed material.

Example 3-1 Dye (Sunchromin Fast Blue MB: manufactured by Sumitomo Chemical) 4.0% acetic acid
2.0% stem salt
5.0% Ribbon agent (Nitsukor N500: manufactured by Nikko Chemical) 1.0% Molten solution obtained in Example 1 (first cycle) (converted to pure chromium content)
0.35% Example 3-2 Dye (Sunchromine Flu Black R ConC: manufactured by Sumitomo Chemical Co., Ltd.)
1.5% dye (Sunchromine Pure Blue B e Genra: manufactured by Sumitomo Chemical Co., Ltd.)
0.4% dye (Sunchromine Prilliant Violet Rconc: manufactured by Sumitomo Chemical Co., Ltd.)
0.2% acetic acid
1.2% Ramie 5.
0% loose beam agent (Nikkor N500) 1.
0% Eluent obtained in Example 2 (3rd cycle) (contained pure chromium) 0.3% Example 3-3 For dyeing of light color hues, the melt used was decolorized with commercially available activated carbon. and dyed with the following recipe.

Dye (omega chrome flavin CIG: manufactured by Sandoz) 1.0% acetic acid Acid
1.0%E nitric acid
5-0% Eluent obtained in Example 1 (first cycle) (contained pure chromium content)
The results of measuring the hue and color fastness of fabrics dyed with 0.175% or more are shown in the 4th section.
As shown in the table, there was no difference between the fabrics and the fabrics dyed by conventional methods.

Table 4: Measurement of color fastness (test method: according to JIS LIO06 wool fabric test method).

Claims (1)

[Claims] 1 6 discharged from the textile dyeing process using acidic mordant dyes
In a method for recovering hexavalent chromium from wastewater containing valent chromium and reusing it for dyeing with an acidic mordant dye, (a)
(b) adsorbing hexavalent chromium from the hexavalent chromium-containing wastewater using a highly crosslinked salt-type weakly basic anion exchange resin having a pyridine bone structure in its main chain or side chain;
a step of desorbing the hexavalent chromium-adsorbing resin with an alkaline aqueous solution to obtain a hexavalent chromium-containing eluent; (c) chromium treatment during dyeing with an acid mordant dye using the hexavalent chromium-containing eluent as it is or after treatment; A method for reusing hexavalent chromium in dyeing wastewater using an acidic mordant dye, the method comprising the step of reusing it as a dye.