JP2688009B2 - Method for recovering organic quaternary ammonium hydroxide from waste liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering organic quaternary ammonium hydroxide from a waste liquid, and more specifically, it mainly discharges water from the manufacturing process of semiconductor devices, printed circuit boards, liquid crystal display devices, etc. The present invention relates to a method for efficiently and inexpensively recovering valuable quaternary organic ammonium hydroxide from a waste liquid containing organic quaternary ammonium oxide and resist stripped products.

[0002]

2. Description of the Related Art In recent years, the demand for semiconductor devices, printed circuit boards, liquid crystal display devices, etc. has increased with the development of electrical and electronic technologies, and the developer used in the developing process after photo-etching and Si wafers have been accordingly increased. The amount of alkaline aqueous solutions such as cleaning liquids used in the cleaning process of liquid crystal glass substrates and liquid crystal glass substrates is increasing, and at the same time, the amount of alkaline waste liquid discharged from these manufacturing processes is rapidly increasing. With regard to the alkaline aqueous solution used in such a manufacturing process, high purity is required as the degree of integration of semiconductor devices increases and as patterns in printed boards and liquid crystal display devices become finer. Since it is necessary to cope with this high purification, an aqueous solution of an organic quaternary ammonium hydroxide such as tetramethylammonium hydroxide (TMAH) or β-hydroxyethyltrimethylammonium hydroxide (choline) is often used.

Therefore, in the alkaline waste liquid from the manufacturing process of such semiconductor devices, printed circuit boards, liquid crystal display devices, etc., the organic quaternary ammonium hydroxide derived from the developing solution or the cleaning solution is usually about 100 to 20,000 ppm. In the case of a developing solution, it is usually a resist stripper derived from various photosensitive resins such as a mixture or condensate of quinonediazide and phenol novolac resin used as a resist in the case of a developing solution (photodegradable photoresist). 10 to
It is contained at a concentration of about 1,000 ppm. Therefore, with respect to such a waste liquid, in the past, it is the actual situation that the waste liquid is neutralized, then microbially decomposed by activated sludge and discharged, or appropriately concentrated and burned. Therefore, at present, useful substances such as TMAH and choline contained in such waste liquid are also discarded together with the waste liquid treatment.

Attempts have also been made to recover useful substances such as TMAH and choline from such waste liquid, or to regenerate them as a developer. That is, in Japanese Patent Application Laid-Open No. 60-247,641, waste water containing organic quaternary ammonium ions derived from TMAH and the like is concentrated by reverse osmosis filtration, and the obtained concentrated water is electrolyzed to obtain the concentrated water. A method of recovering an organic quaternary ammonium ion as an organic quaternary ammonium alkali has been proposed. Further, in JP-A-58-30753, the photoresist is adsorbed and removed by using an activated carbon tower and a filtration tower. Then, a method of regenerating the developing solution by adding a developing stock solution to the obtained filtrate and adjusting the pH has been proposed.

However, in the former method, it is necessary to physically concentrate the organic quaternary ammonium hydroxide such as TMAH to a certain concentration using an expensive reverse osmosis membrane, and the reverse osmosis used at this time is required. Considering the durability of the membrane, the pH range that can be used for a long time is actually pH 1
If the pH value of the waste liquid is about 0 or less and the pH value of the waste liquid is high, the durability of the reverse osmosis membrane becomes a problem, and the waste liquid to which this method can be applied is limited. Moreover, in this reverse osmosis filtration, the concentration ratio that can be concentrated by one time of reverse osmosis filtration is as low as about 4 times at most, and it is usually necessary to concentrate to a desired concentration in the next electrolysis step, for example, about 1 to 2%. In addition to requiring multiple reverse osmosis filtration operations, it is usually performed with a constant concentration ratio, but if the concentration of the waste liquid is not stable, the concentration of the obtained concentrated liquid will not be stable and is difficult to use. There is also a problem that some of the ions leak out into the filtrate,
Secondary treatment is unavoidable in order to discharge the filtrate, and the recovery rate of valuables is also reduced. In addition, the resist stripper and the surfactant contained in the waste liquid are also concentrated at the same time as the organic quaternary ammonium hydroxide, and it is considered that these are attached to the reverse osmosis membrane. There are problems that the performance and durability are reduced, the recovery efficiency of the organic quaternary ammonium hydroxide is reduced, and the life of the reverse osmosis membrane is short. For this reason, this method of reverse osmosis filtration requires a great deal of processing cost and has a problem that satisfactory results cannot always be obtained. Also, in the latter method,
Activated carbon has a small adsorption capacity and requires a considerable amount of use, but it is too expensive to discard because it is expensive,
On the other hand, there is a problem in that the reuse also requires a high cost. Moreover, it is unavoidable that impurities such as metal ions and fine particles are mixed from the activated carbon, and this is not an appropriate method for recovering high-purity organic quaternary ammonium hydroxide.

[0006]

Therefore, the inventors of the present invention have prepared a valuable substance, organic quaternary ammonium hydroxide, from a waste liquid containing at least such organic quaternary ammonium hydroxide in a high purity as much as possible, and As a result of intensive studies on a method of efficiently and inexpensively recovering, when such a waste liquid was brought into contact with a cation exchanger, an organic quaternary ammonium ion was selectively and selectively applied to the cation exchanger. The present invention has been completed by finding that they are efficiently adsorbed. Therefore, an object of the present invention is to recover organic quaternary ammonium hydroxide, which is a valuable resource, from waste liquid containing at least organic quaternary ammonium hydroxide at a relatively high purity efficiently and inexpensively. It is to provide a method for recovering organic quaternary ammonium hydroxide.
Further, another object of the present invention is to efficiently recover organic quaternary ammonium hydroxide from a waste liquid containing at least organic quaternary ammonium hydroxide, thereby treating the organic quaternary ammonium hydroxide after recovery. For water C
It is to provide a method for recovering organic quaternary ammonium hydroxide from a waste liquid, which can be treated water with low OD and clean. Still another object of the present invention is to contact a waste liquid containing at least an organic quaternary ammonium hydroxide and a resist stripper with a cation exchanger to selectively and efficiently only the organic quaternary ammonium ion. Organic quaternary ammonium hydroxide, which is a valuable substance, can be easily and surely separated by adsorption on an exchanger, and valuable quaternary ammonium hydroxide can be recovered in a relatively high purity, efficiently and inexpensively from a waste liquid. It is to provide a method for recovering tetraammonium.

[0007]

That is, the present invention is a method for recovering the above organic quaternary ammonium hydroxide from a waste liquid containing at least organic quaternary ammonium hydroxide, which comprises contacting the waste liquid with a cation exchanger. Adsorption step of adsorbing the organic quaternary ammonium ion in the waste liquid to the cation exchanger, and elution to elute the organic quaternary ammonium ion by contacting the eluent with the cation exchanger adsorbing the organic quaternary ammonium ion It is a method of recovering organic quaternary ammonium hydroxide from waste liquid, which comprises a step and an electrolysis step of electrolyzing the eluate obtained in this elution step to recover an aqueous solution of organic quaternary ammonium hydroxide. Further, in the present invention, in the electrolysis step, the eluate is electrolyzed in an electrolytic cell using a cation exchange membrane as a diaphragm, and the anolyte extracted from the electrolytic cell is circulated in the elution step to form a cation exchanger. It is a method of recovering organic quaternary ammonium hydroxide from a waste liquid, which is used as an eluent of adsorbed organic quaternary ammonium ions.

In the method of the present invention, the waste liquid to be treated contains at least organic quaternary ammonium hydroxide, and in addition to these, when organic quaternary ammonium hydroxide is used as a developing solution. The resist stripper that is inevitably included in the waste liquid of this developer, various surfactants and small amounts of other organic substances such as alcohol and ether that are added to this developer as necessary. It may include one. These other organic substances, unless they are present as cations, pass through the cation exchanger without being chemically adsorbed by the cation exchanger and interfere with the adsorption of the organic quaternary ammonium hydroxide. I won't. However, if these other organic substances are present in a too large amount, the COD value of the cation exchange-treated water obtained by contacting with the cation exchanger will show a high value, and these other substances such as activated sludge treatment will be shown. The treatment for removing the organic substance is required. Here, the composition of a typical waste liquid discharged from the developing process of semiconductor device manufacturing shows that the organic quaternary ammonium hydroxide is about 500 to 5,000 ppm,
The resist peeling material is about 10 to 100 ppm, and the surfactant is about 0 to several tens ppm.

In the present invention, first, such a waste liquid is brought into contact with a cation exchanger to adsorb organic quaternary ammonium ions in the waste liquid onto the cation exchanger. Regarding the cation exchanger used in this adsorption step, it may be any one that can efficiently adsorb the organic quaternary ammonium ion derived from the organic quaternary ammonium hydroxide, even if it is a weakly acidic cation exchanger, It may also be a strong acid cation exchanger. And, regarding the substrate of this ion exchanger, even if it is an organic exchanger such as an ion exchange resin,
Further, it may be an inorganic exchanger such as zeolite or silica gel, and the shape thereof may be any of powder, granule, film, fiber and the like. These cation exchangers include, for example, a combination of a weakly acidic cation exchanger and a strongly acidic cation exchanger, a combination of an inorganic exchanger and an organic exchanger, and a plurality of cation exchangers having different shapes. A plurality of cation exchangers can be appropriately combined and used in consideration of the type and properties of the waste liquid, the release after treatment with the cation exchanger, and the like. These cation exchangers are preferably granular weakly acidic cation exchange resins and / or strongly acidic cation exchange resins in view of their handleability, economic efficiency, ion exchange capacity, and presence or absence of impurity elution. Is.

Regarding the cation exchanger, which is weakly acidic or strongly acidic is used, the following advantages and disadvantages of the weakly acidic cation exchanger and the strongly acidic cation exchanger are taken into consideration. , Reuse of the recovered organic quaternary ammonium hydroxide, the treatment method of the cation-exchange treated water that has passed through the adsorption step, the elution step or the electrolytic step method that is a subsequent step, etc. are selected as appropriate. Is good. [Advantages and disadvantages of weakly acidic cation exchanger and strongly acidic cation exchanger] The usable pH range is 4 for weakly acidic cation exchanger.
-14, and the strong acid cation exchanger is 0-14. The adsorption rate of organic quaternary ammonium ions is higher in the strongly acidic cation exchanger than in the weakly acidic cation exchanger. For neutral salts, strongly acidic cation exchangers have resolution, whereas weakly acidic cation exchangers have no resolution. Regarding the eluability of the adsorbed organic quaternary ammonium ion, in the case of a weakly acidic cation exchanger, it is possible to easily elute not only strong acids but also relatively weak acids such as carbonic acid and acetic acid as eluents. It is possible to elute using a relatively small amount of acid. On the other hand, in the case of a strongly acidic cation exchanger, it is not easy to use a strong acid as an eluent, and in order to increase the elution rate, a large excess of strong acid exceeding 10 times that of organic quaternary ammonium ions is required. Must be used. Regarding the ion exchange capacity, the weakly acidic cation exchanger is generally larger than the strongly acidic cation exchanger. When recovering the organic quaternary ammonium hydroxide by electrolyzing the eluate recovered by elution, the free acid concentration increases in the latter half of this electrolysis process, but if the eluent is a strong acid, corrosion of the electrolytic membrane and electrodes may occur. There may be problems.

Here, as the cation exchanger, specifically, styrene-based, acrylic-based, methacrylic-based, tetrafluoroethylene-based polymers or copolymers, and these polymers or copolymers with a crosslinking agent such as divinylbenzene. A cation exchange resin formed into a gel type or porous type by introducing a sulfonic acid group or carboxylic acid group into a modified modified polymer or modified copolymer as a substrate, or an inorganic cation exchanger such as zeolite or silica gel. Is mentioned.

As a cation exchange treatment method for contacting the waste liquid and the cation exchanger, a conventionally known method can be appropriately adopted depending on the type and shape of the cation exchanger. A column method in which the cation exchanger is packed in the column and the waste liquid is allowed to pass continuously, a batch method in which the cation exchanger is added to the waste liquid and contacted with stirring, followed by filtration to perform solid-liquid separation, etc. Can be adopted.

The cation exchanger having adsorbed the organic quaternary ammonium ion in the waste liquid in the above adsorption step is then contacted with an aqueous solution of various acids and / or salts or an eluent composed of water to form a cation exchanger. To elute organic quaternary ammonium ions in the eluate. Whether to use an aqueous solution of acid and / or salt or water as an eluent in this elution step is appropriately determined depending on the type of the cation exchanger used and the subsequent electrolysis step. When using, usually, hydrochloric acid, nitric acid,
Inorganic acids such as sulfuric acid and carbonic acid, organic acids such as acetic acid and formic acid are used, and when an aqueous salt solution is used, carbonates, bicarbonates, sulfates and the like are preferable as the type of salt. The base forming the is the same organic quaternary ammonium as the one to be eluted. Further, their concentration is also appropriately selected and used from a wide range of 0.01 to 20%, and when water is used, pure water is preferably used from the viewpoint of avoiding contamination of impurities. used. Of these, preferred are non-electrolytic acids that do not generate harmful gas on the anode side during electrolysis in the next electrolysis step and can be used repeatedly without being consumed, and among them, high purity hydroxide From the viewpoint of recovering the organic quaternary ammonium, carbonic acid is more preferable, and sulfuric acid having a low concentration of about 0.05 to 2.0% is preferable.

The electrolysis step of electrolyzing the eluate obtained in the elution step to recover the organic quaternary ammonium hydroxide aqueous solution is not particularly limited, but a high-purity organic quaternary ammonium hydroxide aqueous solution is used. For recovery, the method described in JP-B-63-15,355 is preferably used. This method uses an electrolytic cell that uses a cation exchange membrane as a partition, and circulates the eluate on the anode chamber side for a predetermined residence time, and at the cathode chamber side, a low concentration of organic quaternary ammonium hydroxide. The aqueous solution is circulated, and organic quaternary ammonium ions generated on the side of the anode chamber when a current is passed between the anode and the cathode are selectively moved to the side of the cathode chamber. This is a method in which the concentration of tetraammonium is increased and a high-concentration organic quaternary ammonium hydroxide aqueous solution is recovered from this cathode chamber.

In the present invention, the anolyte extracted from the anode chamber in the electrolysis process of the eluate is circulated and used as an eluent to elute the organic quaternary ammonium ions adsorbed on the cation exchanger. It is preferable to recover the organic quaternary ammonium hydroxide by electrolysis. As a result, even when an aqueous solution of acid and / or salt or water is used as the eluent, the organic quaternary ammonium hydroxide in the eluate eluted in the elution step is moved to the cathode chamber side in the electrolysis step. Since the anolyte extracted from the anode chamber in this electrolysis step is reused as the eluent again, the organic quaternary ammonium ion adsorbed on the cation exchanger can be eluted by using a small amount of the eluent. Here, when an aqueous acid solution is first used as the eluent, the eluate usually contains an acid and a salt formed from the acid radical and an organic quaternary ammonium ion eluted from the cation exchanger. There is.
Then, when this eluate is electrolyzed, a part of the salt is decomposed, the organic quaternary ammonium ions move to the cathode chamber side to become organic quaternary ammonium hydroxide, and the acid corresponding to the amount is generated in the anode chamber side. To generate. Therefore, since the acid concentration of the anolyte is higher than that of the original eluate and the concentration of organic quaternary ammonium ions is lower, this anolyte is circulated again to the elution step as the eluent, and the cation exchange is performed. It can be used to elute the organic quaternary ammonium ion adsorbed on the body, and by repeating this operation, the organic quaternary ammonium ion can be eluted in the elution step while recovering the organic quaternary ammonium ion in the electrolysis step. You can As a result, when using an aqueous acid solution as the eluent,
The use of a low-concentration aqueous acid solution reduces the problem of corrosion of the electrolytic membrane and electrodes, and free acid radicals are mixed as impurities in the organic quaternary ammonium hydroxide aqueous solution recovered through the electrolytic membrane. It can be prevented as much as possible, and a high-purity organic quaternary ammonium hydroxide aqueous solution can be obtained.

When an aqueous salt solution is first used as the eluent, or when an aqueous solution of an acid and a salt is used, the salt in the eluent is decomposed in the electrolysis step, which is different from the case of the above aqueous acid solution. Similarly, organic quaternary ammonium hydroxide is produced on the cathode chamber side, and acid is produced on the anode chamber side. Therefore, the anolyte extracted from the anode chamber of the electrolysis step can be circulated as the eluent of the elution step and used for elution of the organic quaternary ammonium ion adsorbed on the cation exchanger, and by repeating this operation, The organic quaternary ammonium hydroxide can be recovered in the electrolysis step while the organic quaternary ammonium ions are eluted in the elution step. As the salt used here, carbonate, bicarbonate, sulfate and the like are preferable, and the most preferable base for forming this salt is the same organic quaternary ammonium as the one to be eluted. . And when using water as the eluent,
As a cation exchanger, it is limited to a weakly acidic cation exchanger, and its elution rate is slower than that when an acid aqueous solution or salt aqueous solution is used, but there is no problem of corrosion of the electrolytic membrane or electrode. Suitable for recovery of high-purity organic quaternary ammonium hydroxide aqueous solution.

By the way, in the cation exchange-treated water obtained through the adsorption step of contacting with the cation exchanger, the organic quaternary ammonium ion in the waste liquid is adsorbed by the cation exchanger and removed. Then, when the waste liquid is derived from a developer, for example, the resist stripping substance is present in the waste liquid, but the presence of the resist stripping substance hinders the adsorption of the organic quaternary ammonium ion to the cation exchanger. However, almost all of it does not adsorb to the cation exchanger and passes through this cation exchanger and remains in the cation exchange treated water. When the waste liquid is, for example, derived from a washing liquid, a surfactant is present in the waste liquid, and a part thereof is adsorbed at the beginning of contact with the cation exchanger. The presence of the agent does not hinder the adsorption of the organic quaternary ammonium ion to the cation exchanger. Similarly, even when a small amount of alcohol or ether is present in the waste liquid, these alcohols or ethers pass through the cation exchanger without being adsorbed, remain in the cation exchange-treated water, and remain in the organic quaternary ammonium. Does not hinder the adsorption of ions to the cation exchanger. Therefore, for the cation-exchange treated water obtained by contacting with the cation exchanger, the next treatment method is determined according to what kind of COD-causing substance and how much it contains.
For example, as for the waste liquid generated in the developing process and the cleaning process for manufacturing a semiconductor device or a liquid crystal device, the resist stripped substance is usually the main one. In such a case, the cation-exchange treated water is treated with activated carbon and the resist is removed. By removing the peeled product or adjusting the pH to 7 or less with an acid, the resist peeled product can be precipitated and separated and removed. In the case where the surfactant remains, the surfactant is used as a resist. It can be co-precipitated with the exfoliated material and separated and removed as much as possible.

The acid used for adjusting the pH for precipitating and separating and removing the resist stripped product and the surfactant is not particularly limited, but usually hydrochloric acid, nitric acid, sulfuric acid, carbonic acid or the like. Inorganic acids and organic acids such as acetic acid and formic acid are used, and they are preferably inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid and carbonic acid because they do not affect the economical efficiency, handleability or COD value. In addition, regarding the pH value to be adjusted by this pH adjustment, the standard value of the "Environmental Standard for Conservation of Living Environment"
Since it is 6.5 to 8.5, it can be filtered and discharged as it is if the pH is adjusted to 6.5, for example. The resist stripped product and the surfactant thus precipitated by adjusting the pH can be easily separated and removed by filtering the product.

The treated water obtained by removing the resist stripping material and the surfactant by the above pH adjustment usually has its COD value lowered to such an extent that it can be discharged as it is. Can be released. However, if this treated water contains unacceptable organic substances such as alcohol and ether that cannot be separated and removed by the above pH adjustment, after performing activated carbon treatment or activated sludge treatment with microorganisms as necessary. , Release. As the activated sludge treatment method in this case, a conventionally known method can be employed as it is, and in particular, an organic alkali such as organic quaternary ammonium hydroxide, a resist stripped product, or a surfactant is used as much as possible. Because of the separation and removal, the load of this activated sludge treatment is usually extremely small, and clean treated water can be easily obtained. Further, the resist stripped product and the surfactant thus separated and removed by the pH adjustment and collected are burned or treated as industrial waste.

[0020]

According to the method of the present invention, for example, in recovering valuable organic quaternary ammonium hydroxide from a waste liquid containing organic quaternary ammonium hydroxide and resist stripping products,
The waste liquid is brought into contact with a cation exchanger so that the organic quaternary ammonium ion is selectively adsorbed on the cation exchanger, the organic quaternary ammonium ion adsorbed on the cation exchanger is eluted, and then the obtained elution is carried out. Since the solution is electrolyzed to recover the organic quaternary ammonium hydroxide, it is possible to prevent as much as possible the inclusion of a polymeric material resist stripping material in the recovered organic quaternary ammonium hydroxide aqueous solution, and There is no deterioration of the performance of this cation exchanger due to adherence of polymeric resist strips to the cation exchanger.
The organic quaternary ammonium hydroxide can be recovered efficiently and reliably. For resist stripping products and surfactants that pass through the cation exchanger and remain in the cation exchange treated water, the cation exchange treated water is treated with an acid to adjust the pH to 7
It can be easily separated and removed by adjusting the following.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Using a photo-decomposable resist (trade name: OFPR8800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) as a resist, and using a TMAH aqueous solution of 0.261 mol / l as a developing solution, a waste liquid [pH] generated in a developing process of semiconductor device manufacturing. : 1
2, TMAH: 2,000 ppm, stripped resist: 3
8 ppm, nonionic surfactant: 46.9 dyne /
cm], and the waste liquid according to the following example was treated.

Example 1 100 ml of a weakly acidic cation exchange resin [trade name: C-464 manufactured by Sumitomo Chemical Co., Ltd.] was used as a cation exchanger.
This was packed in a column having a length of 300 mm and a diameter of 50 mm to prepare an ion exchange resin column. The waste liquid 10 was passed through the ion exchange resin column at a flow rate of 20 ml / min.
20 g of TMAH in the waste liquid was adsorbed by passing 1 liter.

Next, 300 ml of 0.015 mol / l sulfuric acid aqueous solution was used as an eluent, and this eluent was supplied to an ion exchange resin column to adsorb tetramethylammonium ion (TM ion) on the cation exchange resin. And the resulting eluate is supplied to the anode chamber of the electrolytic cell and developed in this anode chamber, then the anolyte extracted from the anode chamber is returned to the ion exchange resin column and circulated at a flow rate of 100 ml / min. It was Also, as the catholyte, 0.029 mol / l TM
Using 230 ml of AH aqueous solution, this catholyte is supplied at a flow rate of 10
It was circulated in the cathode chamber at 0 ml / min. Electrolysis was carried out by passing a direct current of voltage 24 to 52 V and current 2 A between the anode and the cathode. Elution and electrolysis are performed in parallel for about 10 hours, and 0.7
320 ml of a 02 mol / l TMAH aqueous solution was recovered.

The TMAH aqueous solution thus recovered was colorless and transparent, and the amount of resist exfoliation product was 3 ppm or less. In addition, TMAH for TMAH existing in the waste liquid
The recovery rate was about 99%. Also, the collected TMAH
The aqueous solution was diluted to a concentration of 0.261 mol / l used as a developing solution, and the concentration of metal impurities was measured by the graphite furnace atomic absorption spectrophotometry and the concentration of anions was measured by the ion chromatography. Table 1 shows the results.

Example 2 100 ml of a weakly acidic cation exchange resin (trade name: MWC-1 manufactured by Dow Chemical Co.) was used as a cation exchanger,
This was packed in a column having a length of 300 mm and a diameter of 50 mm to prepare an ion exchange resin column. The waste liquid 16 was passed through the ion exchange resin column at a flow rate of 10 ml / min.
The liter was passed to adsorb 31 g of TMAH in the waste liquid.

Next, carbonic acid gas was blown into 400 ml of pure water to adjust the pH to 4.8, and the obtained carbonated water was used as an eluent. The TM ions adsorbed on the exchange resin were eluted, the resulting eluate was supplied to the anode chamber of the electrolytic cell, and after developing in this anode chamber, carbon dioxide gas was added to the anode liquid extracted from the anode chamber at 50 ml / min. It was returned to the ion exchange resin column while being blown at a speed, and circulated at a flow rate of 100 ml / min. As the catholyte, 312 ml of 0.55 mol / l TMAH aqueous solution was used, and the catholyte had a flow rate of 100 ml.
/ Min circulated to the cathode chamber. Voltage 22 between anode and cathode
Electrolysis was carried out by applying a direct current of 55 V and a current of 0.26 to 2.0 A. Elution and electrolysis were performed in parallel for about 16 hours to recover 377 ml of a 1.262 mol / l TMAH aqueous solution.

The aqueous TMAH solution thus recovered was colorless and transparent, and the amount of resist peeled off was 3 ppm or less. In addition, TMAH for TMAH existing in the waste liquid
The recovery rate was about 89%. Also, the collected TMAH
The aqueous solution was diluted to a concentration of 0.261 mol / l used as a developing solution, and the metal impurity concentration and the anion concentration were measured in the same manner as in Example 1. Table 1 shows the results.

Example 3 100 ml of a weakly acidic cation exchange resin [trade name: C-464 manufactured by Sumitomo Chemical Co., Ltd.] was used as a cation exchanger,
This was packed in a column having a length of 300 mm and a diameter of 50 mm to prepare an ion exchange resin column. The waste liquid 10 was passed through the ion exchange resin column at a flow rate of 20 ml / min.
22 g of TMAH in the waste liquid was adsorbed by passing 1 liter.

Next, 400 ml of 0.14% acetic acid aqueous solution (pH 3.8) was used as an eluent, and this eluent was supplied to an ion exchange resin column to elute the TM ions adsorbed on the cation exchange resin. The obtained eluate was supplied to the anode chamber of the electrolytic cell, developed in this anode chamber, and then the anolyte extracted from the anode chamber was returned to the ion exchange resin column and circulated at a flow rate of 100 ml / min. Further, as a catholyte,
312 ml of 54 mol / l TMAH aqueous solution was used, and this catholyte was circulated in the cathode chamber at a flow rate of 100 ml / min.
Electrolysis was performed by applying a direct current of 55 V and a current of 0.3 to 1.1 A between the anode and the cathode. Elution and electrolysis were performed in parallel for about 12 hours to recover 375 ml of a 1.052 mol / l TMAH aqueous solution.

The TMAH aqueous solution thus recovered was colorless and transparent, and the amount of resist peeled off was 3 ppm or less. In addition, TMAH for TMAH existing in the waste liquid
The recovery rate was about 94%. Also, the collected TMAH
The aqueous solution was diluted to a concentration of 0.261 mol / l used as a developing solution, and the metal impurity concentration and the anion concentration were measured in the same manner as in Example 1. Table 1 shows the results.

Example 4 500 ml of a strongly acidic cation exchange resin [trade name: SK-112 manufactured by Mitsubishi Kasei Co., Ltd.] was used as a cation exchanger, and this was packed in a column having a length of 300 mm and a diameter of 80 mm. An ion exchange resin column was prepared. 50 L of the waste liquid was passed through the ion-exchange resin column at a flow rate of 25 ml / min to adsorb 100 g of TMAH in the waste liquid.

Next, 200 ml of a 0.05 mol / l sulfuric acid aqueous solution was used as an eluent, the eluent was supplied to an ion exchange resin column, and the TM adsorbed on the cation exchange resin was used.
Ions are eluted, the resulting eluate is supplied to the anode chamber of the electrolytic cell, and after developing in this anode chamber, the anolyte extracted from the anode chamber is returned to the ion exchange resin column and the flow rate is 200
Circulated at ml / min. Further, 800 ml of 0.06 mol / l TMAH aqueous solution was used as the catholyte, and this catholyte was circulated in the cathode chamber at a flow rate of 200 ml / min. Electrolysis was performed by applying a direct current of 25 to 50 V and a current of 2.5 A between the anode and the cathode. Elution and electrolysis are performed in parallel for about 25 hours, and a 0.65 mol / l TMAH aqueous solution 1,10
0 ml was collected.

The TMAH aqueous solution thus recovered was colorless and transparent, and the amount of resist peeled off was 3 ppm or less. In addition, TMAH for TMAH existing in the waste liquid
The recovery rate was about 61%. Also, the collected TMAH
The aqueous solution was diluted to a concentration of 0.261 mol / l used as a developing solution, and the metal impurity concentration and the anion concentration were measured in the same manner as in Example 1. Table 1 shows the results.

Example 5 As a cation exchanger, 50 ml of a weakly acidic cation exchange resin [trade name: IRC-50 manufactured by Organo Corporation] was used,
This was packed in a column having a length of 300 mm and a diameter of 50 mm to prepare an ion exchange resin column. The waste liquid 10 was passed through the ion exchange resin column at a flow rate of 20 ml / min.
1 liter was passed through to adsorb 14.6 g of TMAH in the waste liquid.

Next, 400 ml of pure water was used as the eluent, this eluent was supplied to the ion exchange resin column, the TM ions adsorbed on the cation exchange resin were eluted, and the resulting eluate was stored in the electrolytic cell. After being supplied to the anode chamber and developed in this anode chamber, the anolyte extracted from the anode chamber was returned to the ion exchange resin column and circulated at a flow rate of 100 ml / min. In addition, as a catholyte, 0.54 mol / l TMAH aqueous solution 3
50 ml were used and this catholyte was circulated in the cathode compartment at a flow rate of 50 ml / min. Electrolysis was carried out by applying a direct current of 55 V and a current of 0.1 to 0.38 A between the anode and the cathode.
Elution and electrolysis were performed in parallel for about 23 hours, and 369 ml of a 0.67 mol / l TMAH aqueous solution was recovered.

The TMAH aqueous solution thus recovered was colorless and transparent, and the amount of resist exfoliation was 3 ppm or less. In addition, TMAH for TMAH existing in the waste liquid
The recovery rate was about 36%. Also, the collected TMAH
The aqueous solution was diluted to a concentration of 0.261 mol / l used as a developing solution, and the metal impurity concentration and the anion concentration were measured in the same manner as in Example 1. Table 1 shows the results.

[0037]

[Table 1] As is clear from the results in Table 1, the TMAH aqueous solutions recovered in Examples 1 to 5 were used as the developer.
The purity was as high as that of the H aqueous solution.

[0038]

EFFECTS OF THE INVENTION According to the method of the present invention, valuable organic quaternary ammonium hydroxide is recovered from waste liquid containing at least organic quaternary ammonium hydroxide with high purity, efficiently and at low cost. In addition, the treated water after the recovery of the organic quaternary ammonium hydroxide can be clean treated water with low COD. Even when the waste liquid contains the organic quaternary ammonium hydroxide and the resist stripper, only the organic quaternary ammonium ion can be selectively and efficiently adsorbed to the cation exchanger, which facilitates both. In addition, the organic quaternary ammonium hydroxide, which is a valuable substance, can be recovered in high purity with high purity.

Claims (5)

(57) [Claims] 1. A method for recovering the organic quaternary ammonium hydroxide from a waste liquid containing at least organic quaternary ammonium hydroxide, which comprises contacting the waste liquid with a cation exchanger to remove organic quaternary ammonium ions in the waste liquid. An adsorption step of adsorbing to a cation exchanger, an elution step of contacting an eluent to the cation exchanger having adsorbed the organic quaternary ammonium ion to elute the organic quaternary ammonium ion,
And a step of electrolyzing the eluate obtained in the elution step to recover an organic quaternary ammonium hydroxide aqueous solution. 2. In the electrolysis step, the eluate is electrolyzed in an electrolysis cell using a cation exchange membrane as a diaphragm, and the anolyte extracted from the electrolysis cell is circulated in the elution step and adsorbed on the cation exchanger. The method for recovering organic quaternary ammonium hydroxide from the waste liquid according to claim 1, which is used as an eluent for organic quaternary ammonium ions. 3. The method for recovering organic quaternary ammonium hydroxide from a waste liquid according to claim 1, wherein the cation exchanger is a weakly acidic cation exchange resin. 4. The method for recovering organic quaternary ammonium hydroxide from a waste liquid according to claim 1, wherein the waste liquid contains at least organic quaternary ammonium hydroxide and a resist stripper. 5. The method for recovering organic quaternary ammonium hydroxide from a waste liquid according to claim 1, wherein the eluent is an aqueous solution of acid and / or salt or water.