JPH11138156A - Ultraviolet oxidation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the UV oxidation device utilizing a photocatalyst by which the efficiency in oxidizing the org. matter in water with UV is improved. SOLUTION: The UV oxidation device 10 consists of a spiral slender quartz tube 14 provided around a cylindrical UV irradiation lamp 12. Many titanium oxide-coated hollow glass beads for promoting the UV oxidation of the org. matter in liq. are packed in the hollow part of the quartz tube from the inlet end to the outlet end. A wire-mesh screen is furnished at least to the outlet end of the quartz tube to prevent the beads from being entrained by the liq. current and driven out of the tube. Otherwise, a hollow vessel contg. suspended titanium oxide-coated hollow glass beads, with at least a part made of a transparent material and provided with the inlet end and outlet end to pass water through the vessel is arranged close to and below the UV irradiation lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a total organic carbon measurement system (sometimes referred to as a "TOC meter") for measuring total organic carbon (TOC) in water, which typically represents the degree of water pollution. Also, the present invention relates to an improvement in an ultraviolet oxidation apparatus used in an ion exchange TOC removal system or the like for completely removing organic fine particles and colloidal organic molecules in water, and irradiating ultraviolet light to organic matter in water to oxidize the same.

[0002]

2. Description of the Related Art Water used for cleaning semiconductors, for producing medical chemicals and injection solutions, for chemical analysis, etc. contains impurities,
For example, it is indispensable to contain substantially no dissolved substances such as fine particles, various ions, microorganisms such as bacteria, and organic compounds. A system for producing such pure water generally uses a combination of various filtration means including a reverse osmosis method, a distillation method, an ion exchange method, an adsorption method, a vacuum degassing method, an ultraviolet oxidation method, and an ultrafiltration method. In particular, for example, in the semiconductor manufacturing field,
Since the intervals between circuits have become narrower as the degree of integration of LSIs has increased, it has been necessary to further purify semiconductor cleaning water in order to prevent short circuits.
Bacteria and organic matter must be removed as much as possible.

[0003] As one of the methods for expressing the cleanliness of pure water, total organic carbon (TO), which indicates the degree of contamination by the amount of carbon in organic matter in water, is referred to as TOC.
C) values (expressed in μg / l or ppb). For reference, a TOC value of 0.20 μg / l or less may be required for semiconductor cleaning applications.

As a means for measuring the TOC value of pure water, a TOC meter of an ultraviolet (UV) oxidation method is widely used. In such a TOC meter, after the conductivity of the sample water flowing in the measurement line is measured by the first conductivity sensor, the sample water is introduced into an ultraviolet irradiation unit, and the sample water is irradiated with ultraviolet light. Irradiation converts organic carbon in the sample water into organic acids. Thereafter, the conductivity of the sample water is measured by the second conductivity sensor, and the TOC value of the sample water is calculated from the known data based on the difference representing the change in the conductivity obtained by the first and second conductivity sensors. Ask.

[0005] Raw water supplied to the semiconductor cleaning pure water production system or recovered and used pure water from the semiconductor cleaning process section may have a considerably high TOC value, and particularly, recovered from the semiconductor cleaning process section. The organic solvent used in the semiconductor cleaning process section may be mixed into the pure water. In this case, the TOC amount of the used pure water is about 500.
ppb or more. In order to reduce the high TOC value in raw water or used pure water containing a TOC amount exceeding a predetermined level, usually, such water is introduced into an ultraviolet irradiation section and irradiated with ultraviolet light to convert organic substances in the water into organic acids. And then removed from the water with an ion exchange device so that pure water with a low TOC value is obtained.

[0006]

One type of a conventional ultraviolet oxidation apparatus used for a TOC meter, an ion exchange TOC removal system, etc., is wrapped around a cylindrical ultraviolet irradiation lamp in order to increase the efficiency of organic matter oxidation by ultraviolet light. And a helical tube made of a transparent material, typically quartz, capable of transmitting ultraviolet light from the irradiation lamp. However, in the conventional ultraviolet oxidation apparatus, a considerably long irradiation time, for example, about 10 minutes is required to completely oxidize the organic matter in the sample water with the ultraviolet light, and thus the measurement time for the TOC meter becomes long. In TOC removal systems, removal efficiency has been limited.

[0007] It is known that titanium oxide has a function as a photocatalyst to promote oxidative decomposition of organic substances dissolved in water. This is because titanium oxide generates OH radicals by interaction with the received light, and this OH radical
It is based on the principle that radicals oxidize organics effectively and quickly. Titanium oxide has been demonstrated to be chemically stable, substantially harmless to the environment, and has no potential toxicity among photocatalytic materials.

In the field of TOC measurement, there is a conventional technique in which a pair of titanium oxide-coated electrodes is arranged and used in an ultraviolet irradiation chamber in order to monitor the oxidation state of organic substances in sample water.

[0009] However, in the configuration of the related art, since the contact area between the sample water and the titanium oxide-coated electrode is limited, it cannot be said that the oxidation of organic substances in water is sufficiently promoted.

In view of the problems in the prior art, an object of the present invention is to provide an improved ultraviolet oxidation using a photocatalyst, which is used in a TOC meter, a TOC removal system, and the like, and promotes the oxidation of organic substances in a liquid by titanium oxide. It is to provide a device.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid passage means which defines an inlet end, an outlet end and a hollow portion communicating therewith, at least a portion of which is made of a substantially transparent material. Irradiating the liquid flowing through the hollow portion from the inlet end to the outlet end through the substantially transparent portion of the liquid passage means, in cooperation with the liquid passage means, thereby irradiating the liquid with ultraviolet light. An ultraviolet irradiation lamp for oxidizing the organic matter to form an organic acid, wherein the hollow portion of the liquid passage means accommodates a large number of titanium oxide-coated hollow glass beads for promoting ultraviolet oxidation of the organic matter in the liquid. An ultraviolet oxidation apparatus characterized in that:

[0012] In one embodiment of the present invention, the liquid passage means comprises a helical elongated quartz tube provided around a cylindrical ultraviolet irradiation lamp, and a spiral hollow portion of the quartz tube is provided in the helical hollow portion of the quartz tube. , From its inlet end to its outlet end, it is substantially filled with titanium oxide-coated hollow glass beads. Preferably, at least at the outlet end of the quartz tube is provided a screen means for preventing the titanium oxide-coated hollow glass beads from being entrained by the liquid flow and coming out of the quartz tube.

[0013] In another embodiment of the present invention, the liquid passage means includes a hollow portion that is disposed adjacent to and below the ultraviolet irradiation lamp and that receives the titanium oxide-coated hollow glass beads in a floating state, and at least includes the hollow portion. It consists of a hollow container partially made of a transparent material. This container has an inlet for introducing a liquid into the hollow part for ultraviolet irradiation and an outlet for sending out water after the ultraviolet irradiation from the hollow part, and the transparent part of the container is an ultraviolet ray leaking through a quartz tube. It is arranged toward the ultraviolet irradiation lamp so as to transmit ultraviolet light from the irradiation lamp into the hollow portion.

A feature of the present invention is that it can be retrofitted to existing UV oxidizers, thus the UV oxidizer of the present invention comprises a spiral quartz tube provided around a cylindrical UV irradiation lamp; A hollow container disposed immediately below the ultraviolet irradiation lamp, the hollow container including a hollow portion for holding the titanium oxide-coated hollow glass beads in a floating state, and at least partially formed of a transparent material. The container has an inlet for introducing a liquid into the hollow portion for ultraviolet irradiation and an outlet for sending water after the ultraviolet irradiation from the hollow portion, and the transparent portion of the container is irradiated with ultraviolet light leaking through a quartz tube. It is arranged toward the ultraviolet irradiation lamp so as to transmit ultraviolet light from the lamp into the hollow portion.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring particularly to FIG. 1 of the drawings, there is shown, as a first embodiment of the present invention, an ultraviolet oxidizing apparatus generally designated by the reference numeral 10. The ultraviolet oxidizing apparatus 10 comprises an elongated transparent spiral quartz tube 14 as a liquid passage means provided around a cylindrical ultraviolet irradiation lamp 12. FIG. 2 is a partially cutaway view showing one turn of the exit end of the spiral tube 14 made of quartz in FIG. 1 in an enlarged manner, and is a view best showing the features of the present invention as described later.

In the first embodiment shown in the figure, the ultraviolet oxidation apparatus 10 is provided, for example, in connection with a sample water measurement line incorporated in a pure water production system for semiconductors, and measures the TOC value of raw water or pure water. Ultraviolet (UV) oxidation method TOC
The quartz tube 14 has an inlet end 16 and an outlet end 18 as a whole, which constitutes a part of a total (not shown).
And a helical passage or hollow 20 extending between the inlet end and the outlet end for passing the sample water. The ultraviolet irradiation lamp 12 irradiates sample water flowing in the spiral tube 14 from the inlet end 16 to the outlet end 18 with ultraviolet light through a transparent quartz wall, thereby completely oxidizing organic substances in the water. Functions to form organic acids. In the known TOC meter, the inlet end 16 of the quartz tube is connected to a first sensor (not shown) for measuring the conductivity of the sample water before irradiation with ultraviolet light collected in the sample water measurement line, and the outlet end 18 thereof. Is connected to a second sensor (also not shown) that measures the conductivity of the sample water in a state where the organic matter has been completely oxidized by receiving ultraviolet light. The TOC meter is connected to the first and second sensors, detects a difference between the measured conductivity values obtained by the first and second sensors, and determines the TOC value of the sample water based on the difference. Means are further provided.

As can be clearly seen in FIG. 2, the helical passage 20 of the quartz tube 14 has a multiplicity of titanium oxide coatings, preferably all over its surface, from its inlet end 16 to its outlet end 18. Of the hollow glass beads 22 are accommodated. As generally known as a type of photocatalyst, the titanium oxide coating applied to such hollow glass beads generates OH radicals in water that promote the oxidation of organic matter in water by interaction with irradiated ultraviolet light. Help to make. By filling titanium oxide in the form of beads in a quartz tube in a floating state, the effective surface area becomes larger than that of titanium oxide coated in two electrodes, for example, so that a larger amount of OH radicals is generated. It will be appreciated that better photocatalysis will thus be obtained.

FIG. 3 is a sectional view taken along line II of an arbitrary portion of the spiral tube turn shown in FIG.
(B), (C) is a diagram exemplarily showing how the titanium oxide-coated hollow glass beads 22 are located in the passage or the hollow portion 20 constituted by the quartz tube wall during the operation of the ultraviolet oxidation apparatus. It is. The beads 22 are not located so as to block the passage cross section, but allow sufficient water to pass between the quartz tube wall and the ultraviolet light from the ultraviolet irradiation lamp without being obstructed so much as shown in the drawing. It must be of a size and shape that allows sufficient irradiation of the entire water. As an example, the passage inner diameter of the quartz tube 14 is about 3 to 4 mm.
In this case, the particle size of the titanium oxide-coated hollow glass beads is about 1.5 to 2 mm. According to the experimental results, it is desirable that about 2 to 3 beads are randomly placed in an arbitrary passage section of the quartz tube.

Referring again to FIG. 2, at the outlet end 18 of the quartz tube, there is provided a means for preventing the titanium oxide-coated hollow glass beads from coming out of the quartz tube with the flow of liquid. 24 are provided. In the illustrated embodiment, the pull-out preventing means is, for example, a thin stainless wire that is rolled and pushed into the inside passage of the quartz tube to serve as a screen or a filter. After insertion, the wire mesh screen 24 is pressed and held against the quartz tube wall by its springback action. Those skilled in the art will recognize various alternatives to such wire mesh screens. in short,
Any filter or screen means is used to allow water to pass, but not to escape the helical tube 14 with the beads entrained. The screen means can be fixed to the quartz tube wall using any conventional fixing means. Preferably, such withdrawal prevention means 24 is also located at the inlet end 16 of the helical tube (not shown).

FIG. 4 is a perspective view showing an ultraviolet oxidizing apparatus 30 as another embodiment of the present invention, and FIG. 5 is a view 5-5 of the ultraviolet oxidizing apparatus 30 of FIG.
FIG. The ultraviolet oxidation apparatus of this embodiment is typically incorporated in series with a TOC removal system provided in a pure water production system for semiconductors, for example, to feed raw water or a liquid to be treated flowing through an inlet end. The organic carbon in the liquid is turned into an organic acid state by irradiating ultraviolet rays, and thereafter, the organic carbon is sent out from the outlet end for the next processing. The organic acid-containing water after the ultraviolet irradiation is then transferred to an ion-exchange resin device, which removes organic acids in the water by ion-exchange action to reduce the total amount of organic carbon in the water and further purify the water. High water.

The ultraviolet oxidizing apparatus 30 has a liquid passage means 32 in the form of a channel-shaped hollow container disposed longitudinally below and near the ultraviolet irradiation lamp 12. The container 32 is a rectangular body 34 having a cross-sectional groove shape open toward the ultraviolet irradiation lamp 12 and a transparent material, preferably quartz, fixedly attached to the top edge thereof by any fixing means, for example, a clamp frame 36. It has a plate-shaped closure 38 made of glass, and a container hollow portion or inner chamber 40 constituted by the main body 34 and the closure 38. The opposite ends of the container body 34 are filled with water 40
There is provided an inlet tubular member 42 for receiving therein and an outlet tubular member 44 for sending out water which has been completely oxidized by irradiation with ultraviolet rays from the chamber 40 from the chamber 40.

As can be seen in FIG. 5, the hollow or internal passage 40 of the container 32 filled with water during flow passage contains a number of titanium oxide-coated hollow glass beads 22 in a floating state. A bead withdrawal preventing means made of a filter may be provided on the inner part of the end of the container body 34 to which the outlet tubular member is attached. If placed below or at the bottom of the container, the beads will be floating and will not fall out of the container 32 without such a draw-out prevention means. The mounting location of the inlet tubular member may be the same.

As in the case of the liquid passage means 14 of the first embodiment, the container 32 as the liquid passage means of the second embodiment also emits ultraviolet rays from an ultraviolet irradiation lamp to the quartz glass plate 3.
8 must be sized and shaped so as to be sufficiently radiated through the titanium oxide-coated hollow glass beads 22 in a floating state in the hollow portion 40 and to the water present thereunder. . Therefore, even if the depth dimension of the chamber 40 is increased to accommodate more beads, the ultraviolet rays hardly reach the water portion at the bottom of the chamber, and the oxidation of organic substances contained therein is not promoted. As an example, if the lateral upper opening dimension of the container on which the quartz glass plate 38 is placed is L and the outer diameter of the ultraviolet irradiation lamp 12 is d, L
It has been experimentally found that it is desirable to satisfy the relationship of = 2 to 3d. When titanium oxide-coated hollow glass beads having a particle size of about 1.5 to 2 mm are used, the depth of the hollow portion of the container is about 3 to 4 mm. According to the experimental results, in this case as well, it is desirable that about 2 to 3 beads are vertically suspended in water in the hollow portion of the container in a vertically overlapping manner. Preferably, the separation distance between the upper surface of the quartz glass plate 38 and the outer peripheral portion of the ultraviolet irradiation lamp 12 is approximately 1 to 1.
3 mm. In order to prevent the ultraviolet rays from the ultraviolet irradiation lamp from reacting with oxygen existing in the gap to generate ozone and thereby reduce the ultraviolet irradiation amount, at least the ultraviolet irradiation lamp and the container 32 are connected to each other. The space between them is preferably sealed by, for example, a cover, and the sealed space is filled with nitrogen gas.

FIG. 6 shows a liquid passage means according to a second embodiment of the present invention in a conventional ultraviolet oxidation apparatus comprising a helical elongated quartz tube 14 provided around an ultraviolet irradiation lamp 12. This shows a configuration example in which the titanium oxide bead container 32 is retrofitted. The container 32 is disposed immediately below the ultraviolet irradiation lamp 12 having the spiral tube 14 in the longitudinal direction, and the quartz glass plate 38 is directed upward. As shown, the inlet 42 of the container 32 is
The outlet 44 is connected to the raw water or pure water source and the spiral quartz tube 1
4 may be connected to the inlet end 16. During the operation of the ultraviolet oxidizing apparatus, water passing through the container 32 receives ultraviolet irradiation from an ultraviolet irradiation lamp that has leaked through the quartz tube 14 through the quartz glass plate 38, and the titanium oxide coated hollow. The photocatalysis of the glass beads 22 promotes the oxidation of the contained organic matter.

FIG. 7 shows the change in the conductivity of water with respect to the time of ultraviolet irradiation using the photocatalyst-based ultraviolet oxidation apparatus of the present invention shown in FIG. The measurement was performed, and the result is shown by a solid line. On the other hand, the results obtained using the conventional ultraviolet oxidation apparatus under the same conditions are indicated by broken lines.

When the benzoxin-containing water is irradiated with ultraviolet light, the conductivity curve rises and peaks as the benzoxin changes into an organic acid, and then falls to a substantially constant value. As is well known to those skilled in the art, the point at which the conductivity takes a constant value is defined as the point of complete oxidation (hereinafter referred to as "F
Point). As can be seen with reference to such a graph, the UV irradiation time at point F of the conductivity curve for the device of the present invention, indicated by the solid line, is about 3 minutes, which is required to completely oxidize benzoxin in water. You can think of it as time. On the other hand, in the case of the conventional machine shown by the dotted line, the ultraviolet irradiation time at the point F is about 6 minutes. Therefore, by using the titanium oxide-coated hollow glass beads according to the concept of the present invention, even organic substances which are relatively hard to oxidize can be completely oxidized in about half the oxidation time as compared with the conventional method. Thus, in the TOC meter embodying the present invention, the TOC
The C value measurement time can be reduced to about 1/2, and the TOC removal system of the present invention doubles the TOC removal efficiency.

[0027]

[Brief description of the drawings]

FIG. 1 is a perspective view of an ultraviolet oxidizing apparatus comprising a helical elongated quartz tube provided around a cylindrical ultraviolet irradiation lamp similarly to the conventional configuration.

FIG. 2 is an enlarged partial cutaway view showing one turn at the outlet end of the quartz spiral tube of FIG. 1, and is a view best showing the features of the present invention.

FIG. 3 shows I- of any part of the spiral tube turn shown in FIG.
FIG. 2 is a sectional view taken along the line I, and is a sectional view (A), (B), (C).
FIG. 5 is a view exemplarily showing how the titanium oxide-coated hollow glass beads 22 are positioned in a passage or a hollow portion formed by a quartz tube wall during operation of the ultraviolet oxidation apparatus.

FIG. 4 is a perspective view showing an ultraviolet oxidizing apparatus as another embodiment of the present invention, in which a container for accommodating hollow glass beads coated with titanium oxide and allowing water to pass therethrough is disposed below the ultraviolet irradiation lamp. FIG.

FIG. 5 is a sectional view of the ultraviolet oxidizing apparatus of FIG. 4 taken along line 5-5.

FIG. 6 is a perspective view showing an example in which features of the present invention are retrofitted to a conventional ultraviolet oxidation apparatus.

FIG. 7 shows a comparative experiment result of the present invention and a conventional configuration in which organic substances in water are irradiated with ultraviolet rays to be in an organic acid state, and the vertical axis plots the conductivity and the horizontal axis plots ultraviolet (UV) irradiation time. FIG.

[Explanation of symbols]

 10, 30 UV oxidation device 12 UV irradiation lamp 14 Spiral quartz tube 16, 42 Inlet end 18, 44 Outlet end 20, 40 Hollow part 22 Titanium oxide coated hollow glass beads 24 Wire mesh screen 32 Titanium oxide coated hollow glass beads container 38 Quartz glass plate

Claims (10)

[Claims] 1. A liquid passage means defining an inlet end, an outlet end and a hollow communicating therewith, at least a portion of which is made of a substantially transparent material, and provided in cooperation with the liquid passage means. And irradiates the liquid flowing in the hollow portion from the inlet end to the outlet end with ultraviolet light through the substantially transparent portion of the liquid passage means, thereby oxidizing organic matter in the liquid to form an organic acid. The hollow portion of the liquid passage means contains a number of titanium oxide-coated hollow glass beads for promoting ultraviolet oxidation of organic substances in the liquid. apparatus. 2. The liquid passage means comprises a helical elongated quartz tube provided around a cylindrical ultraviolet irradiation lamp, and a helical hollow portion of the quartz tube is provided at an inlet end thereof. 2. The ultraviolet oxidation apparatus according to claim 1, wherein the outlet end is substantially filled with titanium oxide-coated hollow glass beads. 3. A screen means is provided at least at an outlet end of the quartz tube so as to prevent the titanium oxide-coated hollow glass beads from falling out of the quartz tube due to the flow of the liquid. 3. The method according to claim 2, wherein
The ultraviolet oxidation apparatus according to the above. 4. The inner diameter of the hollow portion of the quartz tube is about 3 to 4 mm,
The particle size of the titanium oxide-coated hollow glass beads is about 1.5 to
The ultraviolet oxidizer according to claim 2 or 3, wherein the diameter is 2 mm. 5. The liquid passage means includes a hollow portion which is disposed in proximity to and below the ultraviolet irradiation lamp and accommodates the titanium oxide-coated hollow glass beads in a floating state, and at least a part of which is made of a transparent material. The container has an inlet for introducing a liquid into the hollow portion for ultraviolet irradiation and an outlet for sending water after the ultraviolet irradiation from the hollow portion, and the transparent portion of the container is made of quartz. 2. The ultraviolet oxidizing apparatus according to claim 1, wherein the ultraviolet oxidizing device is disposed toward the ultraviolet irradiating lamp so as to transmit the ultraviolet light from the ultraviolet irradiating lamp that leaks through the tube. 6. A screen means is provided at least at an outlet of the hollow container so as to prevent the titanium oxide-coated hollow glass beads from coming out of the hollow container accompanying the flow of the liquid. The ultraviolet oxidation apparatus according to claim 5, wherein 7. The hollow container has a transparent portion disposed at a distance from an ultraviolet irradiation lamp, and a closed space filled with nitrogen gas is defined between the transparent portion and the ultraviolet irradiation lamp. The ultraviolet oxidizing apparatus according to claim 5, wherein 8. The ultraviolet oxidation apparatus measures the conductivity of the sample water flowing into the inlet end and the conductivity of the sample water flowing out of the outlet end, and determines the sample based on a difference between the measured conductivity values. 2. The ultraviolet oxidation apparatus according to claim 1, wherein the ultraviolet oxidation apparatus forms a part of a TOC meter for determining the total amount of organic carbon in water. 9. The TOC according to claim 1, wherein said ultraviolet oxidizing device introduces water flowing out of said outlet into an ion exchange resin device, wherein the organic acid in the water is removed to reduce the total amount of organic carbon in the water. 2. The ultraviolet oxidation apparatus according to claim 1, wherein the ultraviolet oxidation apparatus forms a part of a removal system. 10. A spiral quartz tube which is provided around a cylindrical ultraviolet irradiation lamp, and a hollow tube which is disposed immediately below the ultraviolet irradiation lamp and accommodates titanium oxide-coated hollow glass beads in a floating state. And a hollow container at least partially made of a transparent material, the container being provided with an inlet for introducing a liquid into the hollow portion for ultraviolet irradiation, and an outlet for discharging water after the ultraviolet irradiation from the hollow portion. An ultraviolet oxidizing apparatus having an outlet, wherein the transparent portion of the container is arranged toward the ultraviolet irradiation lamp so as to transmit the ultraviolet light from the ultraviolet irradiation lamp leaking through the quartz tube into the hollow portion. .