JPH1135305A - Production of purified aqueous hydrogen peroxide solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aq. hydrogen peroxide soln. freed of org. carbon components. SOLUTION: Activated carbon is brought into contact with an aq. hydrogen peroxide soln. and the hydrogen peroxide is decomposed by >=0.5 g (expressed in terms of 100% hydrogen peroxide) per 1 g activated carbon to pretreat the activated carbon. The pretreated activated carbon is washed and an aq. hydrogen peroxide soln. is brought into contact with the pretreated activated carbon to produce the objective purified aq. hydrogen peroxide soln. It is preferable that >=90 wt.% of the activated carbon has 6-100 mesh particle diameter and the residue on ignition is >=5 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a purified aqueous hydrogen peroxide solution for removing organic carbon components from an aqueous hydrogen peroxide solution.

[0002]

2. Description of the Related Art In a method for producing hydrogen peroxide by oxidation-reduction of anthraquinones, hydrogen peroxide is generally produced in an organic solvent, and the hydrogen peroxide produced by the reaction is extracted with water to form a peroxide. Manufactures hydrogen aqueous solution. Further, the obtained aqueous hydrogen peroxide solution is purified by distillation, ion exchange resin, or the like, and becomes a high-purity aqueous hydrogen peroxide solution with few impurities, and is widely used in a wafer cleaning process in the semiconductor industry.

[0003] However, in distillation or purification using an ion exchange resin, the effect of removing organic impurity components mixed in the production of the aqueous hydrogen peroxide solution in the aqueous hydrogen peroxide solution is not sufficient, and the organic compound is removed from the aqueous hydrogen peroxide solution. Purification with activated carbon has been devised as one method for removal. For example, there is a method in which powdered activated carbon is added to an aqueous hydrogen peroxide solution, the slurry is brought into contact with the aqueous solution, and the activated carbon is separated from the purified aqueous hydrogen peroxide solution by sedimentation, filtration and the like. In this method, since activated carbon has a strong effect of decomposing hydrogen peroxide, decomposition of hydrogen peroxide continues and foams until the separation is completely completed, so that not only separation of both becomes difficult, but also heat generation during decomposition. And there is a risk of causing explosive decomposition of hydrogen peroxide.

In order to solve this problem, for example, US Pat. No. 2,919,975 discloses a method of diluting an aqueous solution of hydrogen peroxide and bringing the diluted solution into contact with activated carbon at a low temperature. In this method, since an aqueous solution of hydrogen peroxide having a high concentration of hydrogen peroxide cannot be brought into contact with activated carbon, a concentration step of hydrogen peroxide is required as a post-treatment, resulting in a large energy loss.

In order to use activated carbon for the purification of an aqueous hydrogen peroxide solution, a pretreatment operation of activated carbon for suppressing the decomposition of hydrogen peroxide by changing the properties of the activated carbon itself has also been performed. For example, French Patent No. 1475926 discloses a method in which a hydrophobic organic substance such as carbon tetrachloride is added to activated carbon, followed by contact with hydrogen peroxide for purification. In this method, it is possible to reduce the decomposition amount of hydrogen peroxide.However, since a large amount of organic matter is added as a pretreatment of the activated carbon, the organic matter adsorption capacity of the prepared activated carbon is reduced, and the organic carbon component is highly reduced. Cannot be removed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for removing organic carbon components from an aqueous hydrogen peroxide solution by contacting the activated carbon with activated carbon to suppress decomposition of hydrogen peroxide and to reduce the amount of organic compounds contained in the aqueous hydrogen peroxide solution. An object of the present invention is to provide a method for easily removing and purifying carbon components with high removal efficiency.

[0007]

In order to solve the above-mentioned problems, the present inventors have proposed that activated carbon obtained by decomposing hydrogen peroxide has a reduced hydrogen peroxide decomposition activity even after washing as a post-process. The inventor found that there was a certain thing, and as a result of intensive research, came to complete the present invention.

That is, according to the present invention, a) the activated carbon is pretreated by contacting the activated carbon with an aqueous hydrogen peroxide solution and decomposing at least 0.5 g of hydrogen peroxide per 100 g of hydrogen peroxide per 1 g of activated carbon. The present invention relates to a method for producing a purified aqueous hydrogen peroxide solution, comprising the steps of: b) washing the pretreated activated carbon with water; and c) bringing the aqueous hydrogen peroxide solution containing an organic carbon component into contact with the pretreated activated carbon.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In the present invention, in order to suppress the decomposition of hydrogen peroxide during purification by contacting activated carbon with an aqueous solution of hydrogen peroxide, activated carbon is previously contacted with an aqueous solution of hydrogen peroxide and converted to 100% hydrogen peroxide per 1 g of activated carbon. It is characterized by performing pretreatment of activated carbon that decomposes hydrogen peroxide of 0.5 g or more,
If the amount of decomposition is smaller than this, the effect of suppressing the decomposition of hydrogen peroxide during purification is small and not effective.

The aqueous hydrogen peroxide solution used for the pretreatment of the activated carbon is not particularly limited.
In order to avoid the adhesion of impurities to activated carbon, it is preferable to use a hydrogen peroxide aqueous solution having a low impurity concentration.

The method of contacting the activated carbon with the aqueous solution of hydrogen peroxide at the time of pretreatment is carried out while stirring appropriately in a container having an open top in order to easily remove oxygen gas generated by decomposition of hydrogen peroxide. It is desirable to do. In addition, it is desirable to use an aqueous solution of hydrogen peroxide that is at least 50 times the weight of the activated carbon at the time of the pretreatment. Further, the pretreatment can be performed at a low temperature, for example, room temperature of about 25 ° C., but the treatment can be performed in a short time by heating. However, it is optional whether the treatment is performed at a low temperature for a long time or at a high temperature for a short time.
The present invention is not particularly limited.

The activated carbon that has been subjected to the pretreatment contains an organic substance oxidized to oxygen generated by the decomposition of hydrogen peroxide. If this organic substance is dissolved in an aqueous solution of hydrogen peroxide during purification, the efficiency of purification becomes poor. Therefore, after pretreatment of activated carbon, it is removed by washing with water. At this time, if heated water is used, it becomes possible to remove organic substances soluble in water contained in the activated carbon in a short time. Further, after the water washing, the activated carbon is washed with a warmed aqueous solution of an alkali metal hydroxide such as sodium hydroxide, and the used alkali metal hydroxide is washed with water or neutralized with an aqueous solution of an inorganic acid such as hydrochloric acid. Alternatively, it may be brought into contact with an aqueous solution of hydrogen peroxide to be purified.

The activated carbon used in the present invention is 90% by weight in order to facilitate separation of water or an aqueous solution of hydrogen peroxide from activated carbon during pretreatment, washing with water and purification.
The above are particles having a particle size of 6 to 100 mesh, and those having an impurity content of 5% by weight or less such as a residue on ignition in order to avoid that the activated carbon itself becomes a contamination source of impurities including metals. As such activated carbon, for example, a granular Shirasagi LH2C (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.)
(90% by weight or more, particles having a particle size of 20 to 48 mesh, ignition residue 5% by weight or less).

The contact method between the pretreated activated carbon and the aqueous hydrogen peroxide solution to be purified is as follows: after stirring and contacting by a batch method, the activated carbon and the purified aqueous hydrogen peroxide solution are spontaneously precipitated;
Filtration, separation may be carried out by a general solid-liquid separation operation such as centrifugation, but a method in which a pretreated activated carbon is packed and fixed in a packed tower, and a hydrogen peroxide aqueous solution is passed through is particularly preferable. Continuous purification becomes possible, and separation of the activated carbon and the aqueous hydrogen peroxide solution is achieved in a short time.

The concentration of hydrogen peroxide in the aqueous hydrogen peroxide solution to be purified is not particularly limited.
% By weight is preferred. In addition, since the decomposition rate of hydrogen peroxide increases as the temperature of the aqueous hydrogen peroxide solution increases, the temperature of the aqueous hydrogen peroxide solution during purification ranges from a temperature higher than the freezing point of the aqueous hydrogen peroxide solution to be purified to 40 ° C. -10 ° C.
Preferably, it is maintained at 20 ° C.

In the present invention, the pretreatment of the activated carbon in advance suppresses the decomposition of hydrogen peroxide by the activated carbon, and efficiently removes the organic carbon component in the purified aqueous hydrogen peroxide solution after contact with the activated carbon. Thus, the present invention does not hinder the practice of the present invention even if a stabilizer such as a phosphate group is contained in the produced purified aqueous hydrogen peroxide solution. Furthermore, the purified hydrogen peroxide aqueous solution produced by the present invention is preferably used for semiconductor cleaning and the like by highly removing metals and anions by other purification means such as distillation and contact with an ion exchange resin. A high-purity aqueous hydrogen peroxide solution can be used.

[0017]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the amount of the organic carbon component in the examples uses the total organic carbon (hereinafter abbreviated as TOC) concentration as an index, and this is the total organic carbon analyzer TOC- manufactured by Shimadzu Corporation.
Measured according to 5000.

Example 1 Granulated Shirasagi LH2C (90, manufactured by Takeda Pharmaceutical Co., Ltd.)
Particles having a particle size of 20 to 48 mesh in weight% or more, and ignition residue of 5% by weight or less) 100% by volume of an aqueous solution of hydrogen peroxide having a hydrogen peroxide concentration of 8% by weight and a TOC concentration of 1 μg / ml or less based on the dry weight. Then, in a temperature range of 20 to 40 ° C., 8 g of hydrogen peroxide was decomposed per 1 g of activated carbon. Thereafter, the activated carbon was washed with ultrapure water heated to 80 ° C. for 2 hours. Next, the activated carbon was filtered off, and the obtained activated carbon was subjected to purification in a hydrogen peroxide concentration of 31.2% by weight and a TOC concentration of 7.
μg / ml aqueous hydrogen peroxide solution of 10% of dry weight of activated carbon
A 0-fold amount was added, and the mixture was stirred at 2 ° C. for 4 hours. Thereafter, the purified aqueous hydrogen peroxide solution was filtered through a 0.2 μm PTFE membrane filter, and the hydrogen peroxide concentration and the TOC concentration in the obtained filtrate were determined. As a result, the concentration of hydrogen peroxide in the produced aqueous solution of purified hydrogen peroxide was 31.
1% by weight and the TOC concentration was 2 μg / ml.

Comparative Example 1 The procedure of Example 1 was repeated except that the activated carbon was not brought into contact with an aqueous solution of hydrogen peroxide to carry out a pretreatment for decomposing hydrogen peroxide. As a result, the hydrogen peroxide concentration in the purified aqueous hydrogen peroxide solution was 26.2% by weight, and the TOC concentration was 2 μg / ml.

Example 2 The same operation as in Example 1 was carried out except that the temperature at which the activated carbon was brought into contact with the aqueous solution of hydrogen peroxide to be purified was 30 ° C.
As a result, the hydrogen peroxide concentration in the purified aqueous hydrogen peroxide solution was 30.2% by weight, and the TOC concentration was 2 μg / m 2.
l.

Example 3 Granulated Shirasagi LH2C manufactured by Takeda Pharmaceutical Company Limited (90% by weight)
The above are particles having a particle size of 20 to 48 mesh, and the ignition residue is 5% by weight or less.
An aqueous solution of hydrogen peroxide having an OC concentration of less than 1 μg / ml
Double amounts were added to decompose 3 g of hydrogen peroxide per 1 g of activated carbon at 40 ° C. Thereafter, the activated carbon was washed with ultrapure water heated to 80 ° C. for 2 hours. Then, activated carbon
A PFA packed column having a diameter of 0 mm and a height of 300 mm was packed with a volume of 16 ml using a polyethylene holding material having a pore diameter of 30 μm. Further, the column was washed by passing ultrapure water heated at 80 ° C. through the column, and then passing an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 31.2% by weight and a TOC concentration of 7 μg / ml for purification. Temperature 2 ° C, Flow rate 240ml /
8 l of liquid was passed as the upward flow of h. As a result, the concentration of hydrogen peroxide in the produced purified aqueous hydrogen peroxide solution was 31.0%.
%, And the TOC concentration was 1 μg / ml.

Comparative Example 2 The same operation as in Example 3 was carried out except that the pretreatment for decomposing hydrogen peroxide by contacting activated carbon with an aqueous solution of hydrogen peroxide was not carried out in advance. As a result, the hydrogen peroxide concentration in the purified aqueous hydrogen peroxide solution was 29.8% by weight, and the TOC concentration was 2 μg / ml.

Example 4 The procedure of Example 3 was repeated, except that 5 l of an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 32.1% by weight and a TOC concentration of 69 μg / ml was used for purification. As a result, the concentration of hydrogen peroxide in the produced aqueous solution of purified hydrogen peroxide was 31.7.
% By weight, and the TOC concentration was 11 μg / ml.

Comparative Example 3 The same operation as in Example 4 was carried out except that the pretreatment for bringing the activated carbon into contact with an aqueous solution of hydrogen peroxide to decompose hydrogen peroxide was not carried out. As a result, the hydrogen peroxide concentration in the purified aqueous hydrogen peroxide solution was 29.4% by weight, and the TOC concentration was 13 μg / ml.

[0025]

According to the present invention, there is provided a purification method for removing organic carbon components in an aqueous hydrogen peroxide solution by a simple operation to a high degree while suppressing the decomposition of hydrogen peroxide.

Claims (2)

[Claims] A) a step of pretreating activated carbon by contacting activated carbon with an aqueous hydrogen peroxide solution and decomposing at least 0.5 g of hydrogen peroxide per 100 g of hydrogen peroxide per 1 g of activated carbon; b) A method for producing a purified aqueous hydrogen peroxide solution comprising a step of washing the pretreated activated carbon with water and a step of contacting an aqueous hydrogen peroxide solution containing an organic carbon component with the pretreated activated carbon. 2. Activated carbon having a particle size of 6 to 1 at 90% by weight or more.
The method according to claim 1, wherein the particle size is 00 mesh and the residue on ignition is 5% by weight or less.