CN1191996C - Method for utilizing sulfuric acid/peroxide liquid mixture - Google Patents

Abstract

The present invention has developed a technology for utilizing sulfuric acid contained in the waste liquid mixture. A waste liquid mixture containing sulfuric acid and peroxide is collected, and the peroxide is decomposed in the presence of a decomposition accelerator. The decomposition accelerator is selected from nitric acid, fuming nitric acid, nitrogen dioxide, nitrate compounds and hydrochloric acid. Since these accelerators can be obtained from waste materials, these waste liquids can be reused and can be effectively used to solve the problems associated with waste liquid disposal.

Description

A method using a mixture of sulfuric acid and peroxide

technical field

The present invention relates to a kind of method utilizing sulfuric acid and peroxide mixture. More particularly, the present invention relates to a process utilizing a sulfuric acid and peroxide mixture which has the advantage of reusing the spent sulfuric acid and peroxide mixture.

Background technique

So far, in most semiconductor processing processes, a large amount of sulfuric acid and peroxide mixtures are still used as semiconductor chip rinse solutions, either in the form of sulfuric acid/hydrogen peroxide aqueous solution or in the form of sulfuric acid/ozone mixed solution.

This sulfuric acid and peroxide mixed solution is a typical rinsing solution mainly used to peel off the photosensitive resist on the semiconductor wafer or remove metal particles, especially heavy metal particles. The amount of this mixed solution is much larger than that of other flushing solutions, such as ammonia/hydrogen peroxide solution, hydrochloric acid/hydrogen peroxide solution or dilute hydrofluoric acid.

This results in a large amount of waste liquid after use. The following problems will occur when the waste liquid of this mixed liquid is disposed of:

(i) If these effluents are mixed with water, a large amount of heat will be generated (related to the heat of hydration of sulfuric acid);

(ii) leaves a peroxyacid (permonosulfuric acid) with strong oxidizing power; and

(iii) Aqueous hydrogen peroxide solution is left, as a result of impact or mixed impurities, making it easy to generate violent foam (foam produced by oxygen).

Due to the problems caused by the above-mentioned rapid pressure rise due to heat release and foaming, or the possibility of equipment damage due to oxidation, it is difficult to transport these waste liquids and purify them directly into sulfuric acid. Therefore, conventionally, the waste liquid is diluted and cooled with a large amount of water, then neutralized with an alkali such as slaked lime, followed by flocculation with an inorganic flocculant and a polymer flocculant, and finally discharged as waste water.

Due to the use of a large amount of water or chemical reagents such as flocculants that are tens to hundreds of times the initial sulfuric acid and peroxide mixture, the treatment costs are increased, that is, equipment or maintenance costs, and chemical reagents or sludge disposal costs. If the waste liquid is treated in this way, the amount of waste discharge will also increase.

Hitherto, it has been considered that there is no possibility of re-use other than discharging the spent sulfuric acid and peroxide mixture as waste water effluent.

Contents of the invention

As mentioned above, the disposal of the waste sulfuric acid and peroxide mixture has many disadvantages, and the present inventors attempted to develop a technique for efficiently reusing the waste liquid and solving the problems associated with the waste liquid disposal. In the course of research, the present inventors have completed the present invention, the purpose of which is to develop a technology for utilizing sulfuric acid and peroxide mixed liquid as its waste liquid, and to provide a method for utilizing the waste liquid and solving the problems related to waste liquid disposal Methods.

The present invention provides a method of utilizing a mixture of sulfuric acid and peroxide, the method comprising decomposing peroxide in the mixture of sulfuric acid and peroxide so that the mixture is used as sulfuric acid.

Since the peroxide is decomposed in the sulfuric acid and peroxide mixture, the obtained mixture can be used as sulfuric acid. If the above waste liquid is treated with this technology, the waste of sulfuric acid and peroxide mixture can be effectively reused. liquid. This not only effectively utilizes the waste liquid, but also solves the problems associated with waste liquid disposal. The present invention provides a kind of effective treatment technology for the waste liquid of sulfuric acid and peroxide mixed liquid, wherein sulfuric acid and peroxide are left as a component, if hope waste liquid is utilized as sulfuric acid, the present invention also It can be used as a method of using the mixed solution of sulfuric acid and peroxide, and it can be applied to the treatment of the mixture of sulfuric acid and peroxide other than the mixed solution of waste sulfuric acid and peroxide.

The present invention has been accomplished based on the following information obtained by the inventors. That is, in order to solve the above-mentioned problems, the present inventors have carried out persistent research, and thus found that when a decomposition accelerator such as nitric acid is added to a mixture of sulfuric acid and peroxide, this waste liquid can be utilized as regenerated sulfuric acid, such as this Waste liquid is the waste liquid generated in the semiconductor production process. This finding has led to the completion of the present invention.

According to the present invention, a new method of utilizing the mixture of sulfuric acid and peroxide is provided, so that it is now possible to use the mixture of spent sulfuric acid and peroxide as sulfuric acid. As a result, the waste liquid can be used without disposal, thereby effectively utilizing resources and reducing the discharge of waste such as waste water. In addition, with the present invention, the peroxide can be completely decomposed without reducing the concentration of sulfuric acid in the waste liquid. The resulting product can be used as a modifier for various compounds such as polymers, such as a sulfonating agent or a hydrolysis accelerator. The decomposed solution obtained by decomposing peroxides can be used as an improvement agent for waste resin materials, thereby converting these wastes into high value-added materials, and protecting the global environment by reducing the amount of waste and effectively utilizing natural resources.

Detailed ways

The content of the present invention is described below with reference to the preferred embodiments, and these embodiments are only for illustration purposes, and cannot limit the protection scope of the present invention.

The present invention decomposes peroxide in the sulfuric acid and peroxide mixture, utilizes the sulfuric acid and peroxide mixture as sulfuric acid, and finds the most effective way to utilize the sulfuric acid and peroxide mixed waste liquid, these waste sulfuric acid The mixed solution of sulfuric acid and peroxide is obtained from various fields of use of the mixed solution of sulfuric acid and peroxide, thereby avoiding various problems caused by the disposal of these waste solutions.

According to the present invention, the concentration of sulfuric acid contained in the mixture of sulfuric acid and peroxide is not lower than 70wt%, preferably not lower than 80wt%. This is because, if the concentration of sulfuric acid is lower than 70 wt%, the peroxide is not easily decomposed even if a decomposition accelerator as will be described later is added.

There is no particular limitation on the field of use of the mixed solution of sulfuric acid and peroxide. In general, sulfuric acid and peroxide mixtures are best from various cleaning processes. For example, sulfuric acid and peroxide mixed solution are preferably the rinsing solution for rinsing various components or products in the electronic field, especially preferably the rinsing solution for peeling off the resist in the semiconductor production process or as various cleaning solutions, because, The concentration of sulfuric acid in the mixture of sulfuric acid and peroxide used in the semiconductor production process is usually greater than or equal to 70wt%.

The peroxide in the mixture of sulfuric acid and peroxide can be hydrogen peroxide, ozone and peroxyacid (peroxymonosulfuric acid). It should be noted that generally peroxysulfuric acid is produced by injecting aqueous hydrogen peroxide or ozone gas into sulfuric acid.

The concentration of peroxide in the mixture of sulfuric acid and peroxide is not particularly limited. Usually, the concentration is preferably 0.001 ppm-20 wt%, more preferably 0.01 ppm-10 wt%. There is no particular problem if the mixed liquor contains, in addition to sulfuric acid and peroxide, various components such as water, inorganic acids, surfactants or decomposition stabilizers. The total content of these third components is preferably not more than 30wt%, because the higher the content of these third components, the easier it is to hinder the decomposition of peroxide in the mixed solution.

When the peroxide is decomposed in the mixed solution of sulfuric acid and peroxide, the temperature is not particularly limited. There will be no particular problem if the decomposition temperature is in the range of 0°C to 180°C, which is usually the temperature at which a mixture of sulfuric acid and peroxide is used. Generally, the higher the temperature of the mixture at the time of decomposition, the faster the rate of decomposition or foaming of the peroxide.

Preferably, one or more of nitric acid, fuming nitric acid, nitrogen dioxide, nitrate or hydrochloric acid is added to the mixture of sulfuric acid and peroxide as a decomposition accelerator for its peroxide. The concentrations of these compounds which have not been used or which have been used are not particularly limited. From the viewpoint of efficient use of natural resources, it is preferable to use used compounds. For the same reason, any of the waste liquids of the above-mentioned decomposition accelerators of the semiconductor wafer cleaning liquid used in semiconductor processing is preferably used as the decomposition accelerator in the method of the present invention. The appropriate amount of decomposition accelerator added to the mixture of sulfuric acid and peroxide can be determined depending on the type or concentration of peroxide or the temperature of the liquid. Usually, the addition amount of the decomposition accelerator in the mixed solution is preferably 0.001 ppm-10 wt%, more preferably 0.01 ppm-5 wt%. When the decomposition accelerator is added, if the mixture is stirred sufficiently, the decomposition accelerator can be well dispersed, thereby increasing the decomposition speed or reducing the amount of the decomposition accelerator.

The above-mentioned decomposition reaction occurs when the mixed solution is used, such as in a semiconductor wafer rinse tank in a semiconductor processing process, or in an apparatus dedicated to the decomposition reaction. Since a large amount of gas, mainly oxygen, is usually generated in the existing decomposition reaction, and the heat of decomposition is generated, it is best to install a stirring device and/or cooling device to reduce the heat of decomposition, or take appropriate measures, such as a pressure-resistant structure or setting Pressure relief line to prevent liquid level rise or pressure rise due to gas bubbling.

In order to efficiently perform decomposition, it is desirable to inject droplets of a decomposition accelerator into the mixed solution under stirring. Usually the decomposition reaction has a high reaction rate, so if the decomposition accelerator is injected all at once, it will be difficult to control foaming or exothermic reactions.

By adopting the above treatment method, the decomposition of peroxide in the sulfuric acid and peroxide mixed liquid can be completed in a very short time, so that the treated liquid can be reused as sulfuric acid. For example, treated liquids can be reused as strong acids or sulfonating agents. For example, sulfuric acid obtained from a mixture of sulfuric acid and peroxide in this manner can be used as a sulfonating agent for high molecular compounds, or used for hydrolysis reactions of high molecular compounds.

A very small amount of decomposition accelerator has a decomposition effect, so the sulfuric acid in the mixture of sulfuric acid and peroxide is hardly reduced. After decomposing in this way, when purifying the treatment liquid, the regeneration efficiency is obviously improved, so that the generated sulfuric acid can be easily regenerated into concentrated sulfuric acid, and the cost is reduced at the same time.

In addition, the treatment liquid from the decomposition process can be used as sulfuric acid in a decomposed state. For example, the treatment liquid in the decomposed state can also be used as a sulfonating agent for various compounds, as a sulfonating agent for unsaturated compounds containing aromatic compounds, halogens, alcohols, or for compounds containing acid anhydride groups, especially for hydrocarbon-based organic compounds. A sulfonating agent for compounds, or as a hydrolysis accelerator for various compounds. More specifically, the treated liquor can be used in the synthesis of alkylbenzenesulfonates (ABS). The above compounds are useful as dispersants for various substances, ie surfactants, or as antistatic agents.

The treatment liquid can also react with polystyrene to produce polystyrene sulfonate and its sodium salt, which can be used as various dispersants, for example, as dispersants for cement or coal slurry, as heat-resistant thermoplastic resins, for As an antistatic agent for paper, resin or fiber, as a flocculant for sewage treatment, or as a paste or ion exchange resin. The treatment liquid can also react with lignin to produce lignosulfonic acid and its salt, which can be effectively used as a dispersant for cement. The treatment liquid can also hydrolyze acrylonitrile groups in ABS resin, SAN resin or PAN resin to modify the resulting hydrolyzed product and use it as a hygroscopic resin.

Compounds such as organic compounds after treatment with the treatment liquid in a decomposed state may be pre-use compounds or post-use compounds, ie, waste. From the viewpoint of efficient use of natural resources, it is preferable to use waste as a raw material. For example, used waste plastic material is preferably used as raw starting material.

The above treatment can effectively decompose the peroxide in the spent sulfuric acid and peroxide waste mixture, thereby facilitating the recovery of high-concentration sulfuric acid. The recovered sulfuric acid can not only be used for its own purification as regenerated sulfuric acid, but also can be used as various compounds, such as sulfonating agent or hydrolysis accelerator for various organic compounds.

In conventional practice, a large amount of water and chemicals are required to treat the sulfuric acid and peroxide mixture, which will eventually generate a large amount of waste. Now it is possible to significantly reduce the amount of these wastes. In addition, the mixed liquor that has been discarded until now can be converted into high value-added products. In addition, it is likewise possible to convert waste plastic materials that have hitherto been discarded into products with high added value.

It can be seen from the above content that the technical solution of the present invention can save or recycle resources, reduce the amount of waste, and thus protect the earth's environment.

The content of the present invention will be described below with reference to several preferred embodiments, and these embodiments are only used to illustrate the present invention, but not to limit the protection scope of the present invention. In Examples 1 and 2, the decomposition of peroxides in the effluent mixture of sulfuric acid and peroxides is described. Similarly, in Examples 3-9, specific examples of decomposition products using a mixed solution of sulfuric acid and peroxide are described together with Comparative Examples. In the following examples, the decomposition of peroxides in sulfuric acid and peroxide mixtures and the utilization of their decomposition products are described. The following sulfuric acid and peroxide waste mixtures (a) and (b) were used for evaluation:

(a) Before the oxide film formation in the semiconductor processing process (pre-step), the waste liquid of sulfuric acid and peroxide mixed liquid used as the cleaning liquid for pretreatment (initial mixing volume ratio is H ₂ SO ₄ /H ₂ O = 5:1, the temperature used is 80°C, and a small amount of hydrogen peroxide aqueous solution is added during use); and

(b) In the resist peeling step (preliminary step) of semiconductor processing, the waste liquid of the sulfuric acid and peroxide mixed liquid used as the resist liquid (bubble ozone gas in concentrated sulfuric acid, the temperature used is 110°C).

The initial concentrations of sulfuric acid and aqueous hydrogen peroxide were 96 wt% and 30 wt%, respectively.

Example 1

5 liters of waste liquid (a) was injected into the reactor equipped with a stirrer and cooling device, and cooled to water temperature. Under stirring, 5 drops of fuming nitric acid waste liquid are added dropwise in the waste liquid, and the weight of each drop is about 0.2 grams. This fuming nitric acid waste liquid is used as a resist stripping liquid in the metal interconnection step in the semiconductor processing process. From where the nitric acid was added dropwise, foam due to the decomposition of the peroxide appeared and disappeared again within about 2 minutes. Analyze the remaining amount of hydrogen peroxide aqueous solution in the waste liquid before and after the decomposition reaction. It was found that after decomposition, the remaining amount of about 1 wt% was reduced to 10 ppm or less. The concentration of sulfuric acid in the decomposed solution obtained by the decomposition was 82% by weight. The sulfuric acid obtained after purification can be reused as industrial sulfuric acid.

Example 2

At a temperature of 110°C, add 7 drops of 10wt% sulfuric acid dropwise to 20 liters of waste liquid (b) installed in the semiconductor chip cleaning tank, and the weight of each drop is about 0.3 grams. The filter, similar to the case of Example 1, from the point where the nitric acid was dropped, showed foam due to the decomposition of the peroxide. The foam disappeared within about 1 minute. Before and after the decomposition reaction, a resist solution was added dropwise to the waste liquid. As for the solution before decomposition, after injecting the resist solution, the whole solution turned light yellow, and within about 3 minutes, the solution became transparent again as before. The decomposed solution will remain light yellow. The reason for this is that the decomposition of peroxide in the waste liquid has been completed. The concentration of sulfuric acid in the decomposition liquid obtained by the decomposition was 90 wt%. Like Example 1, the purified sulfuric acid can be reused as industrial sulfuric acid.

Example 3

In the decomposed solution (concentration of sulfuric acid is 82wt%) obtained in 5 gram embodiment 1, add 0.2 gram waste (ABS resin) of 8mm cassette tape protective plate gray part, then react at 80 ℃ temperature for 60 minute. After the reaction, the solid product was recovered and washed with water until the acid was gone. The resulting gel product was dried at 80°C for 2 hours. The hygroscopicity of the obtained black solid substance to pure water and simulated urine was about 100 times and about 50 times its own weight, respectively.

Example 4

Under the same conditions as in Example 3, a reaction was carried out using a transparent styrene-acrylonitrile (SAN) resin as a raw material and the decomposed liquid obtained in Example 2 (concentration of sulfuric acid: 90 wt%). The hygroscopic capacity of the obtained transparent solid substance to pure water and simulated urine was about 150 times and about 70 times its own weight, respectively.

Comparative example 3' (comparative example of embodiment 3)

Use a mixture of sulfuric acid and peroxide (a). That is, waste liquid that has not undergone oxidation decomposition is used. In addition, this reaction was performed under the same conditions as in Example 3. In this case, the residual peroxide is used to completely decompose the resin waste, but not to convert the waste resin material into hygroscopic resin.

Comparative example 4' (comparative example of embodiment 4)

Use a mixture of sulfuric acid and peroxide (b). That is, waste liquid that has not undergone oxidation decomposition is used. In addition, this reaction was performed under the same conditions as in Example 4. In this case, as in Comparative Example 3', the waste SAN resin material could not be converted into hygroscopic resin.

Example 5

In polystyrene (Mw=ca.280,000) dissolved in 1,2-dichloroethane, add the decomposed liquid obtained in Example 1 (the concentration of sulfuric acid is 82wt%) and acetic anhydride (molar ratio 1:1:2), the thermal reaction was carried out at a temperature of 60° C. for 5 hours. After the reaction, the reaction product was poured into hot water for washing and reprecipitation. The resulting precipitate was dried to 10 mol% sulfonated polystyrene (SPS). The sulfonation ratio is adjusted by changing the addition ratio of recovered sulfuric acid. The obtained sulfonated polystyrene (SPS) was dissolved in tetrahydrofuran. To the obtained solution was added an aqueous sodium hydroxide solution in an amount equimolar to that of the sulfonic acid groups in sulfonated polystyrene (SPS). The resulting solution was recovered and dried into sodium sulfonated polystyrene (SPS-Na). Compared with the glass transition temperature of the polystyrene raw material (about 100°C), the glass transition temperature (Tg) of the resulting sulfonated polystyrene sodium (SPS-Na) was increased by about 40°C. That is to say, after this treatment, polystyrene can exhibit heat resistance.

Example 6

Processing was carried out in the same manner as in Example 5, except that CD-ROM drive case waste (polystyrene-polyphenylene ether blend polymer; containing carbon black) was used. The glass transition temperature (Tg) of the resulting resin was increased by approximately 30°C compared to the initial waste glass transition temperature.

Comparative example 6' (comparative example of embodiment 6)

Here a sulfuric acid/ozone mixture is used. In addition, this reaction was performed under the same conditions as in Example 6. In this case, the expanded styrene waste is completely decomposed during the sulfonation reaction.

Example 7

Polystyrene beads cross-linked with 5% divinylbenzene were injected into the decomposed liquid obtained in Example 2, and a sulfonation reaction was performed at a temperature of 80° C. for 15 hours. After the reaction is finished, the sulfonated product is washed with a large amount of water to obtain a cation exchange resin.

Example 8

18 g of the decomposed liquid obtained in Example 1, 8 g of polystyrene (Mw=10,000) and 8 g of naphthalene were mixed together, and then reacted at a temperature of 150° C. for 5 hours. The reaction was cooled to 90°C and 10 grams of water was added. Under the condition that 7 g of 37% formalin was added dropwise, the resulting reactant was reacted at a temperature of 100° C. for 5 hours. After the reaction, 30 grams of water and 10 grams of 48% sodium hydroxide aqueous solution were added to the reaction system. The resulting product was stirred at 80°C for 30 minutes, then 5 g of calcium hydroxide was added and stirred for 1 hour. The final product obtained after filtration can be used as cement dehydrating agent or coal water slurry dispersant.

Example 9

In the reactor that 70 grams of hexanaphthene is housed and maintained at a temperature of 50° C., within about 60 minutes, the decomposed liquid obtained in 12 grams of Example 1 is simultaneously added dropwise, and under heating conditions A solution obtained by dissolving expanded styrene waste material in 68 g of cyclohexane. The temperature was then maintained at 50±2°C and the reaction was allowed to proceed for 1 hour. As the reaction progressed, a syrupy product was formed in the reaction liquid. Under stirring, an aqueous sodium hydroxide solution was gradually added to the reaction system for neutralization. Then the solvent cyclohexane in the reaction system was distilled off under heating. The pH of the remaining aqueous solution was finally adjusted to 8 with sodium hydroxide to produce a 10 wt% polymer electrolyte aqueous solution. The water-soluble polymer electrolyte obtained in this way can be used as a polymer flocculant, or a dehydrating agent for sewage or waste water of a sewage treatment plant.

Claims (9)

1, a kind of utilization comprises the vitriolic method that contains in the waste liquid mixture of sulfuric acid and superoxide, and this method comprises:

One or more be selected from nitric acid, nitrosonitric acid, nitrogen peroxide, nitrate compound and hydrochloric acid decomposition accelerating agent in the presence of decompose described superoxide decomposition step.

2, utilize the vitriolic method that contains in the waste liquid mixture according to claim 1, wherein in sulfuric acid and the peroxide liquid mixture vitriolic concentration more than or equal to 70wt%.

3, according to the method for utilizing sulfuric acid and peroxide liquid mixture of claim 1, wherein the superoxide in sulfuric acid and peroxide liquid mixture is one or more in hydrogen peroxide, ozone or the peroxosulphuric.

4, the vitriolic method that contains in the waste liquid mixture according to utilizing of claim 1, wherein said decomposition accelerating agent derives from described waste material.

5, according to the method for utilizing sulfuric acid and peroxide liquid mixture of claim 1, wherein sulfuric acid and peroxide liquid mixture are the waste liquids from semiconductor fabrication processes.

6, according to the method for utilizing sulfuric acid and peroxide liquid mixture of claim 5, wherein with one or more the decomposition accelerating agents in nitric acid, nitrosonitric acid, nitrogen peroxide, nitrate compound or the hydrochloric acid as superoxide in sulfuric acid and peroxide liquid mixture.

7, according to the method for utilizing sulfuric acid and peroxide liquid mixture of claim 1, wherein the sulfuric acid that will obtain from sulfuric acid and peroxide liquid mixture is as sulphonating agent.

8,, wherein will be used for the sulfonation reaction and/or the hydrolysis reaction of macromolecular compound from the sulfuric acid that sulfuric acid and peroxide liquid mixture obtain according to the method for utilizing sulfuric acid and peroxide liquid mixture of claim 1.

9, the method for utilizing sulfuric acid and peroxide liquid mixture according to Claim 8, wherein said macromolecular compound is the exhausted Plastic wastes.