JPH0443705B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion exchange device, and particularly to an ion exchange device that can efficiently remove hydrogen peroxide from a liquid.

[Background of the Invention and Prior Art] A. Background of the Invention In recent years, the development and mass production of LSIs and super LSIs have been actively carried out. In manufacturing this LSI and super LSI,
Since pure water is used in many cleaning processes, various studies have been conducted on pure water production technology, and technology for producing ultrapure water (pure water that is extremely close to theoretically pure water) is being developed for semiconductor manufacturing. is being developed.

In a system that uses this ultrapure water to clean, for example, semiconductor wafers, cleaning waste liquid is collected and recycled for use. This is mainly to conserve water resources, and although it is cleaning wastewater, it is clearer than the raw water of general ultrapure water production systems.Washing wastewater contains various impurities, albeit in small amounts, and can be discharged as is. This is based on reasons such as that it cannot be disposed of.

Conventionally, this waste water collection has been performed using a system as shown in FIG.

That is, the wastewater from the semiconductor cleaning process 1 is first subjected to activated carbon adsorption treatment in the activated carbon adsorption tower 2 of the recovery system A, then treated and desalted in the ion exchange tower 3, and then further processed by the reverse osmosis membrane device (Fig. (not shown) in an ultraviolet oxidation device 4. In the ultraviolet oxidation device 4, in order to completely oxidize and decompose organic substances, hydrogen peroxide is generally added as an oxidizing agent, and the treatment is performed by irradiating ultraviolet rays in the presence of hydrogen peroxide.

The treated water from the recovery system A, which includes the activated carbon adsorption tower 2, the ion exchange tower 3, and the ultraviolet oxidation device 4, is returned to the pure water production system B. This pure water production system B includes a pretreatment system C (consisting of a coagulation tank 5 and a double-layer filter 6), a primary pure water system D (a reverse osmosis membrane device 7, a degassing tower 8, and an ion exchange device 9). ) and subsystem E (consisting of an ultraviolet sterilizer 10, a mixed bed ion exchange device 11, and an ultrafiltration membrane device 12). Since the hydrogen peroxide added in the oxidizer 4 remains, if this treated water is circulated directly to the pure water production system B, the ion exchange resin in the ion exchange device will oxidize and deteriorate, or the ultrafiltration membrane will be damaged. (UF) or reverse osmosis membrane (RO) may deteriorate. Among ion exchange resins, cation exchange resins are oxidized by hydrogen peroxide, which breaks the main chain of the resin and causes the resin to deteriorate; however, when anion exchange resins are oxidized and deteriorate, the amine of the ion exchange group is cut off. This causes problems such as leaching into the treated water system and deteriorating the quality of the treated water.

Therefore, it has been desired to develop a method for efficiently removing hydrogen peroxide from such aqueous systems.

B. Problems to be solved by conventional techniques and inventions Conventionally, methods for removing hydrogen peroxide from liquids include:
A method of adding a reducing agent and a method of contacting with activated carbon have been proposed. As reducing agents, sodium sulfite, sodium hydrogen sulfite, sodium thiosulfate, etc. are used, and while these react with hydrogen peroxide at a fast reaction rate and can reliably remove hydrogen peroxide, it is difficult to add a reducing agent. It is difficult to control the amount, and in order to reliably remove hydrogen peroxide, it is necessary to add an excessive amount, which has the disadvantage that the reducing agent remains in the liquid. At the same time, since the amount of ions in the liquid increases, it also has the disadvantage of increasing the load on the subsequent ion exchange device.

On the other hand, in the method of contacting activated carbon, a packed bed is usually formed and the liquid is passed through it, but the space velocity (SV)
can only be obtained at a maximum of about 20 (1/hr), which has the disadvantage of increasing the size of the equipment. In addition, when used for a long time, activated carbon may disintegrate and flow out into the processing solution, or microorganisms such as bacteria may grow in the packed bed and flow out into the processing solution.

An object of the present invention is to provide an ion exchange device that can remove hydrogen peroxide extremely efficiently from a solution containing hydrogen peroxide and can obtain pure water of excellent quality. .

[Means and effects for solving the problems] The applicant has solved the problems of the above-mentioned prior art,
A solution containing hydrogen peroxide is brought into contact with a palladium catalyst as a method to quickly and reliably remove hydrogen peroxide with a simple operation without increasing the amount of ions in the treated solution or propagating microorganisms. We have proposed a method for removing hydrogen peroxide with the following characteristics, and have previously applied for a patent. (Special Application No. 179917, 1983,
Hereinafter referred to as "prior application". ) According to the method of this earlier application,
Hydrogen peroxide can be removed extremely efficiently from a liquid containing hydrogen peroxide.

The ion exchange apparatus of the present invention is based on the method of this prior application, and includes a catalyst resin bed in which a catalyst such as palladium is supported on an ion exchange resin and a mixed bed type ion exchange resin bed in one column. The inside of the ion exchange tower is divided into two chambers by a wall with a strainer, one chamber has a raw water supply inlet, and the other chamber has a treated water outlet. One chamber is filled with a catalyst resin in which an anion exchange resin supports a palladium catalyst, and the other chamber is filled with a cation exchange resin and an anion exchange resin to form a mixed bed type. An ion exchange device characterized by the following.

That is, according to the present invention, raw water is first introduced into a catalytic resin bed, and after the hydrogen peroxide it contains is decomposed,
It is introduced into a mixed bed type ion exchange resin bed for treatment.

[Embodiments of the Invention] Examples of the present invention will be described in detail below with reference to the drawings.

FIGS. 1a and 1b are schematic cross-sectional views showing an ion exchange device according to an embodiment of the present invention, where a shows a state during water sampling and FIG. 1b shows a state during regeneration (chemical injection process).

The ion exchange apparatus of the present invention shown in FIG. 1 has a raw water supply port 21 at the top of an ion exchange tower 20, and a treated water drain port 22 at the bottom. A partition wall 23 made of a perforated plate with strainers 31 provided on both sides is provided inside the tower 20, and the inside of the tower 20 is divided into two upper and lower chambers. The supply port 21 and the discharge port 22 are provided with pipes 41 and 42 having valves 35 and 36, respectively.
is connected.

Thus, the upper chamber 24 is filled with catalyst resin S,
The lower chamber 25 is filled with ion exchange resin R to enable mixed bed ion exchange. At the bottom of the lower chamber 25,
A perforated plate 2 is provided with a strainer 32 on its upper surface in order to prevent the ion exchange resin from flowing out and to facilitate the passage of outflow water such as treated water or inflow water such as regeneration liquid.
6 is provided. 27 is the resin S in the upper chamber 24
It is a liquid dispersion pipe provided above the layer, and the valve 37
A pipe 43 having a diameter is connected to the pipe 43. Reference numeral 28 denotes a regenerated waste liquid extraction pipe which is installed at the boundary between the anion exchange resin and cation exchange resin when they are separated during backwashing, and is connected to a pipe 45 having a valve 39. There is. This recycled waste liquid extraction pipe 28 is constructed by wrapping a Saran net (Saran is a registered trademark) or the like around a porous pipe to prevent resin from flowing out. Note that a pipe 44 having a valve 38 is connected to a portion of the discharge pipe 42 between the valve 36 and the discharge port 22.

In the present invention, the catalyst resin is an ion exchange resin supported with palladium, and the amount supported is preferably about 0.1 to 10% relative to the ion exchange resin.

The anion exchange resin used for this catalyst resin exhibits excellent effects with a small amount of palladium supported.
As the anion exchange resin, a strongly basic anion exchange resin based on a styrene-divinylbenzene copolymer is suitable. The ionic form of the anion exchange resin may be either the Cl type or the OH type, but the OH type is more preferable due to its larger processing capacity. To convert a Cl type anion exchange resin into an OH type, it is best to pass an alkali such as sodium hydroxide through it.

In order to support palladium on an anion exchange resin, it is preferable to fill a column with the anion exchange resin and then pass water through an acidic solution of palladium chloride.
At that time, the amount of palladium supported is 0.2 to 10g-Pd/
- It is a resin.

Specifically, the catalyst resin is Lewait OC−
1045 (Cl type strongly basic anion exchange resin supporting palladium) (manufactured by Bayer) or this
One example is the OH type.

The resin for mixed bed ion exchange is a mixture of a strongly acidic cation exchange resin in the H form and a strongly basic anion exchange resin in the OH form. Specifically, a mixture of Diaion PA312 (manufactured by Mitsubishi Chemical Industries, Ltd.) and Diaion PK228 (manufactured by the same company) is suitable.

Below, the procedure for water sampling and regeneration of the ion exchange device of the present invention will be explained.

B. Water sampling (see Figure 1a) Open the valves 35 and 36 and close the valves 37, 38, and 39, and introduce raw water into the tower 20 through the pipe 41 and the raw water supply port 21. First, the catalyst resin in the upper chamber 24 to remove hydrogen peroxide contained in the raw water. Hydrogen peroxide comes into contact with the catalyst resin and is decomposed into water and oxygen.

The raw water from which hydrogen peroxide has been removed in the upper chamber 24 is
The water passes through the slit of the strainer 31 provided on the perforated plate 23 and enters the lower chamber 25, where it is subjected to ion exchange treatment.
The treated water passes through the slit, is discharged from the treated water outlet 22 at the bottom of the tower 20, and is sent to the next process via the pipe 42.

(b) Regeneration (see Figure 1b) When the quality of the treated water has deteriorated and the ion exchange capacity has decreased, or after a predetermined amount of water has been sampled, valves 35 and 36 are closed and the raw water is supplied. stop. Next, the valve 38 is opened, and the backwash water is introduced from the pipe 44 to the lower part of the tower 20, and is discharged from a drain pipe (not shown) branched from the raw water pipe 41 between the valve 35 and the raw water supply port 21. When the inside of the column is left standing for a predetermined period of time after backwashing, in the lower chamber 25, as shown in FIG. 1b, the cation exchange resin 52 with a heavy specific gravity is on the bottom, and the anion exchange resin 51 with a light specific gravity is on the top. Cation exchange resin 52
After separation of the anion exchange resin 51 and the anion exchange resin 51, the valve 3
7, 38, 39 are opened, and from piping 43
The NaOH solution and the HCl solution are passed through the column 20 through the pipe 44, and the regenerated waste liquid is discharged through the take-out pipe 28 and the pipe 45. By supplying NaOH solution from the top of the column, anion exchange resin 51
At the same time, the catalyst resin S is also converted into OH type and regenerated at the same time. Furthermore, by passing the NaOH solution through the catalyst resin S in this manner, the proliferation of viable bacteria can be prevented. The cation exchange resin is regenerated by HCl solution from the bottom of the column.

After dosing the chemicals as described above, extrude using the usual method (extrude the regenerating liquid present in the resin layer at the same flow rate in order to use the chemicals without wasting them), and wash (wash away the chemicals). , water removal (draining water to near the surface of the resin), mixing (blow air from below to mix cation exchange resin and anion exchange resin to create a mixed bed), start supplying raw water, discard water (water quality of treated water) Do not collect water until the temperature rises and discard it.) After doing this,
Resume water sampling.

Note that the ion exchange device of the present invention is applicable to purifying various liquids. For example, treated liquid or waste liquid obtained by adding hydrogen peroxide to the industrial wastewater system and performing oxidation, reduction, sterilization, and cleaning (for example, treated water obtained by irradiating ultraviolet rays in the presence of hydrogen peroxide to oxidize and decompose organic substances),
Treated water treated with wastewater using Fuenton's reagent, treated water treated by reducing hexavalent chromium-containing wastewater with hydrogen peroxide, reverse osmosis membranes, ultrafiltration membranes, ion exchange membranes, dialysis membranes, etc. It is also suitable for treating waste liquids etc. that have been sterilized or washed with hydrogen peroxide.

In particular, the device of the present invention is suitable for treating treated water that has been irradiated with ultraviolet rays in the presence of hydrogen peroxide to oxidize and decompose organic matter in order to collect and reuse cleaning wastewater discharged from semiconductor manufacturing processes as ultrapure water. . In this case, as shown in FIG. 3, the ion exchange device 19 of the present invention is replaced with a conventional ion exchange device (9 in FIG. 2), and the treated water of the ultraviolet oxidation device 4 is directly exchanged with the ion exchange device of the present invention. It is introduced into the device 19. By doing this, the treated water from the ultraviolet oxidation device 4 comes into contact with the catalyst resin before coming into contact with the ion exchange resin, and the hydrogen peroxide contained therein is decomposed, thereby preventing deterioration of the ion exchange resin. High purity pure water can be obtained.

[Effects of the Invention] As detailed above, the ion exchange apparatus of the present invention has two beds of catalyst resin and mixed bed type ion exchange resin.
It is a tower-type ion exchange device, and can quickly and reliably treat a liquid containing hydrogen peroxide, such as ultraviolet oxidation treated water containing hydrogen peroxide, without increasing the ion load. Therefore, there is no adverse effect on the downstream side of the treatment liquid, and deterioration of subsequent ion exchange resins, ultrafiltration membranes, reverse osmosis membranes, etc. can be prevented. Furthermore, since the inside of the tower is divided into two sections, the device can be made smaller and requires less installation space. Moreover, it is possible to simultaneously convert the catalyst resin into the OH form when regenerating the anion exchange resin in the mixed bed, and the regeneration operation is easy.

The ion exchange device of the present invention is particularly suitable for use in the recovery and reuse process of cleaning water used in semiconductor manufacturing factories such as IC and LSI.

According to the ion exchange device of the present invention, extremely high purity water can be easily produced, and therefore,
The industrial usefulness of the present invention is extremely high.

[Brief explanation of drawings]

Figures 1a and b are schematic sectional views showing an embodiment of the ion exchange device of the present invention, Figure 2 is a system diagram showing a conventional general pure water production/recovery system, and Figure 3 is a schematic cross-sectional view showing an embodiment of the ion exchange device of the present invention. FIG. 2 is a system diagram showing a pure water production/recovery system in which an exchange device is incorporated. A...Recovery process, B...Pure water production process, C...
Pretreatment step, D... Primary pure water step, E... Sub-step, 4... Ultraviolet oxidation device, 9... Conventional ion exchange device, 19... Ion exchange device of the present invention, 2
0... Tower, 21... Raw water supply port, 22... Treated water outlet, 23... Perforated plate, 24... Upper chamber, 25...
...Lower chamber, 31, 32...Strainer.

Claims (1)

[Claims] 1 The interior of the ion exchange tower is divided into two chambers by a partition with a strainer, one chamber is provided with a raw water supply port, the other chamber is provided with a treated water drain port, and the palladium catalyst is added to the anion exchange resin in one chamber. An ion exchange device characterized in that the other chamber is filled with a supported catalyst resin and the other chamber is filled with a cation exchange resin and an anion exchange resin to form a mixed bed type.