JPH078970A - Removal of alcohol in water - Google Patents

Abstract

PURPOSE:To easily and efficiently decompose and remove alcoholes in water by bringing alcohol-containing water into contact with an oxidizing agent in the presence of a metal catalyst supported on activated carbon before bringing the same into contact with an ion exchange resin. CONSTITUTION:For example, 40mg/l of hydrogen peroxide is added to a soln. prepared by adding 1mg/l of ethanol and 1mg/l of isopropyl alcohol to ultra- pure water as an oxidizing agent. The raw water to which this oxidizing agent is added is passed through a catalytic reaction tower 1 packed with Pt-supported activated carbon and subsequently passed through a weak anion exchange resin tower 2, a strong cation exchange resin tower 3 and a strong anion exchange resin tower 4 in succession. The water passing condition of the catalytic reaction tower 1 is set, for example, to S=2hr<-1> and temp. 20 deg.C and the water passing conditions of the towers 2, 3, 4 are set to SV=1hr<->. By this constitution, alcohols in water, especially, lower alcohols difficult to remove heretofore in water can easily be decomposed and removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing alcohols in water, and more particularly, it can efficiently decompose and remove lower alcohols in water. For example, removal of trace organic substances contained in semiconductor wastewater. It relates to a method for removing alcohols in water effective for treatment.

[0002]

2. Description of the Related Art Conventionally, an activated carbon adsorption method, an ion exchange method, an RO (reverse osmosis membrane separation) method and the like have been adopted as a method for removing a trace amount of organic substances contained in semiconductor waste water.

[0003]

However, each of the above conventional methods has the following problems. Activated carbon adsorption method: The adsorption amount for surfactants and phenols is high, but the adsorption amount for lower alcohols is small. Ion exchange method: Acid and basic substances can be removed, but lower alcohols cannot be removed. RO method: Propanol and ethylene glycol can be removed, but methanol cannot be removed.

As described above, the conventional methods for removing trace organic substances cannot sufficiently remove lower alcohols.

Conventionally, as a semiconductor wastewater treatment system, a method of ion-exchange treatment after adsorption treatment with activated carbon is often used, but as described above, it is difficult to remove alcohols in each treatment. From
Even if these are combined, a sufficient effect cannot be obtained in removing alcohols.

Therefore, in particular, in order to enable recovery and reuse of semiconductor wastewater containing lower alcohols, a method for efficiently removing lower alcohols, which is difficult to remove by conventional methods, has been developed. Is desired.

The present invention has been made in view of the above conventional circumstances, and an object thereof is to provide a method for easily and efficiently decomposing and removing alcohols in water.

[0008]

The method for removing alcohols in water according to the present invention comprises the steps of contacting water containing alcohols with an oxidizing agent in the presence of a metal catalyst having activated carbon as a carrier, and then using an ion exchange resin. It is characterized in that they are brought into contact with each other.

The present invention will be described in detail below. In the method of the present invention, the catalytic metal supported on the metal catalyst having activated carbon as a carrier is preferably a platinum group noble metal or an alloy containing it as a main component from the viewpoint of catalytic effect, and the supported amount is 0.05 to 5% by weight is preferred. The shape of the catalyst is not particularly limited.

On the other hand, hydrogen peroxide (H ₂
O ₂ ), sodium persulfate and potassium persulfate are effective.

The amount of such an oxidant to be used depends on the concentration and type of alcohols in the water to be treated, and is an amount necessary and sufficient for the oxidative decomposition of the alcohols into a compound that is easily adsorbed by the ion exchange resin. It is appropriately determined so that

The reaction temperature can be arbitrarily set in the range of room temperature to 100 ° C., but particularly preferably in the range of room temperature to 40 ° C. When the temperature exceeds the reaction temperature, the reaction efficiency in the catalyst layer increases, but pressurization and cooling operations are required to prevent deterioration of the ion exchange resin, which is not preferable.

As a method for carrying out the method for removing alcohols in water according to the present invention, a catalyst in which a predetermined amount of an oxidizing agent is added to and mixed with raw water (water containing alcohols) and then a metal catalyst having activated carbon as a carrier is filled therein is used. After passing water through the reaction tower, there may be mentioned a method of successively passing water through an ion exchange resin tower, for example, a weak anion exchange resin tower, a strong cation exchange resin tower and a strong anion exchange resin tower. At this time, when it is necessary to heat the raw water, a pipe for feeding the raw water to the catalytic reaction tower and a pipe for discharging the treated water of the catalytic reaction tower are provided with heat exchangers to heat the raw water, It is preferable to perform heat exchange with the treated water in the catalytic reaction column.

The method for removing alcohols in water according to the present invention is extremely effective for removing lower alcohols having 1 to 4 carbon atoms, which are more difficult to remove by conventional methods than organic acids. Specifically, it is effective for decomposing and removing lower alcohols as trace organic substances contained in semiconductor wastewater discharged from the semiconductor manufacturing process.

[0015]

When an alcohol is reacted with an oxidizing agent such as H ₂ O _{2 in} the presence of a metal catalyst having activated carbon as a carrier,
According to the following reaction formula, alcohol is efficiently oxidatively decomposed into aldehyde.

CH ₃ OH + H ₂ O ₂ → HCHO + 2H ₂ O C ₂ H ₅ OH + H ₂ O ₂ → CH ₃ CHO + 2H ₂ O The aldehydes thus produced are easily captured and removed by the ion exchange resin.

As described above, conventionally, a treatment system of activated carbon-ion exchange resin is frequently used as a semiconductor wastewater treatment system. Therefore, the method of the present invention is carried out by loading a metal on activated carbon in a conventional apparatus. It can be easily implemented without the need for design changes.

[0018]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example 1 A solution prepared by adding 1 mg / l each of methanol and isopropyl alcohol to ultrapure water was used as raw water, and 40 mg / l of hydrogen peroxide solution was added as an oxidant to the solution, which was passed through the treatment apparatus shown in FIG. Treated with water. In FIG. 1, 1 is a catalytic reaction tower filled with 0.5 wt% Pt-supported activated carbon, 2 is a weak anion exchange resin tower, 3 is a strong cation exchange resin tower, 4 is a strong anion exchange resin tower, and 11 to 15 Each symbol of is a pipe. That is, the raw water containing the oxidizing agent was passed through the catalytic reaction tower 1 and then passed through the weak anion exchange resin tower 2, the strong cation exchange resin tower 3 and the strong anion exchange resin tower 4 in that order for treatment.

The water flow condition of the catalytic reaction tower 1 is SV = 2.
hr ⁻¹ , temperature 20 ° C., each ion exchange resin tower 2, 3,
The water flow condition of No. 4 was SV = 1 hr ⁻¹ .

The treated water thus obtained is measured using a trace amount TOC meter (“700 type high-sensitivity TOC measuring device” manufactured by Jusco International Co., Ltd.), and the TOC removal rate is determined to decompose and remove alcohols. The performance was evaluated.
The results are shown in Table 1.

Comparative Example 1 The decomposition and removal performance was evaluated in the same manner as in Example 1 except that raw water was passed through an activated carbon packed column which did not carry a metal catalyst instead of the catalytic reaction column, and the decomposition and removal performance was evaluated. The results are shown in Table 1.

Comparative Example 2 Catalytic reaction tower 1 without passing water to ion exchange resin towers 2, 3 and 4.
The decomposition and removal performance was evaluated in the same manner as in Example 1 except that the raw water was passed through only. The results are shown in Table 1.

[0024]

[Table 1]

From Table 1, it is clear that according to the method of the present invention, alcohols can be easily decomposed and removed.

[0026]

As described in detail above, according to the method for removing alcohols in water of the present invention, alcohols in water, particularly lower alcohols which have been conventionally difficult to remove, can be treated under severe reaction conditions. It can be easily decomposed and removed without using it.

The method of the present invention is particularly effective for decomposing and removing lower alcohols as trace organic substances in semiconductor wastewater.

[Brief description of drawings]

FIG. 1 is a system diagram of a processing device used in a first embodiment.

[Explanation of symbols]

 1 Catalytic Reaction Tower 2 Weak Anion Exchange Resin Tower 3 Strong Cation Exchange Resin Tower 4 Strong Anion Exchange Resin Tower

Claims (1)

[Claims] 1. A method for removing alcohols from water, which comprises contacting water containing alcohols with an oxidizing agent in the presence of a metal catalyst having activated carbon as a carrier, and then contacting with an ion exchange resin.