JP3780627B2 - Underwater TOC monitor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an underwater TOC (Organic Carbon) monitor. More specifically, the present invention relates to an underwater TOC monitor that can easily and accurately measure the TOC concentration of a liquid sample having an extremely low impurity concentration, such as ultrapure water for electronic industry.
[0002]
[Prior art]
The ultrapure water for electronic industry has a very high purity, and its TOC concentration is extremely low, such as a concentration of several μg / liter or less. Conventionally, the TOC component present in the sample water is decomposed by irradiating the sample water with ultraviolet rays, and the concentration of bicarbonate ions derived from the generated carbon dioxide is determined using an electric conductivity cell. Measured continuously, TOC concentration was monitored using this value as an index. In addition, in order to grasp the TOC concentration more accurately, sample water is sampled, an oxidant is added to the sample water, it is thermally decomposed, and the generated carbon dioxide is analyzed with an infrared gas analyzer to calculate the TOC concentration. I have done it.
However, the ultraviolet decomposition type TOC meter used for the conventional TOC monitor of ultrapure water has a measurement sensitivity and accuracy of only TOC concentration up to several μg / liter. Water cannot be measured. In addition, the thermal decomposition TOC meter can measure even ultra-pure water of several μg / liter or less, but is not suitable as a field-installed monitor because the apparatus becomes large.
Therefore, there is a need for an underwater TOC monitor that can measure the TOC concentration of ultrapure water with a very low TOC concentration, which is small and light, and that can be measured quickly, simply and accurately.
[0003]
[Problems to be solved by the invention]
The present invention has been made for the purpose of providing an underwater TOC monitor capable of measuring the TOC concentration of ultrapure water having an extremely low TOC concentration quickly and accurately on site.
[0004]
[Means for Solving the Problems]
As a result of intensive research to solve the above-mentioned problems, the present inventor obtained an electrolyte in ultraviolet irradiation treated water obtained by decomposing TOC components in ultrapure water by ultraviolet irradiation using a continuous regeneration type ion exchange apparatus. After concentration, it was found that the TOC concentration in the sample water can be measured quickly and accurately by measuring the electrical conductivity of the resulting concentrated water, and the present invention has been completed based on this finding.
That is, the present invention is an apparatus for continuously measuring the TOC concentration in ultrapure water, an ultraviolet irradiation apparatus for decomposing TOC components in sample water, and an electrolyte in the ultraviolet irradiation treated water by concentrating the electrolyte. An underwater TOC monitor comprising: a continuous regeneration type ion exchange apparatus, and an electric conductivity meter for measuring the electric conductivity of the concentrated water.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The underwater TOC monitor of the present invention is suitable for ultrapure water having a low TOC concentration, particularly ultrapure water having a TOC concentration of several μg / liter or less, such as ultrapure water used in the electronics industry. Can be used.
FIG. 1 is a system diagram of the underwater TOC monitor of the present invention. The underwater TOC monitor of the present invention includes an ultraviolet irradiation device 1, a continuous regeneration type ion exchange device 2, and an electric conductivity meter 3. Continuously regenerative ion exchange device is a device in which ion exchange membranes are arranged alternately in the positive and negative directions, electrodes are arranged at both ends, and mixed ion exchange resin is filled between the membranes. This is an ion exchange device capable of continuously regenerating the resin while removing the electrolyte (ion) by passing a water sample in parallel with the membrane surface.
The sample water is collected directly from the ultrapure water pipe or once as sample water and then sent to the ultraviolet irradiation device 1. The ultraviolet irradiation device to be used is not particularly limited as long as it can decompose the TOC component in the ultrapure water to carbon dioxide. For example, the ultraviolet lamp 4 provided in the periphery like the ultraviolet irradiation device of this embodiment. By irradiating the sample water flowing through the central water passage 5 with ultraviolet rays, the TOC component contained in the sample water is decomposed into carbon dioxide, and the ultraviolet irradiation treatment water in which bicarbonate ions exist in the water can be obtained. .
[0006]
The ultraviolet irradiation treated water is then sent to the continuous regeneration type ion exchange device 2. In the continuous regeneration type ion exchange apparatus 2 of this embodiment, the cathode 6 and the anode 7 are provided on the opposite surfaces, and the two anion exchange membranes 8 and the two cation exchange membranes 9 are alternately provided between them. The two compartments are divided into two concentration chambers 10, one deionization chamber 11, and two electrode chambers 12, and each chamber is filled with a mixed ion exchange resin 13. When a potential difference is applied between the anode and the cathode, the cation passes through the cation exchange membrane, but is blocked by the anion exchange membrane, and the anion passes through the anion exchange membrane, but is blocked by the cation exchange membrane. The bicarbonate ions in the water move from the deionization chamber and the electrode chamber to the concentration chamber and are concentrated in the concentration chamber. The mixed ion exchange resin filled in the deionization chamber, the concentration chamber, and the electrode chamber functions as a bridge having high conductivity and promotes the movement of bicarbonate ions. Water in the deionization chamber from which the bicarbonate ions in the water have moved and the water in the electrode chamber in which a chemical reaction may occur on the surface of the electrode is discharged via the drain pipe 14.
[0007]
In the present invention, the concentration ratio of bicarbonate ions derived from carbon dioxide generated by the decomposition of the TOC component is not particularly limited, depending on the concentration of the TOC component in ultrapure water, the measurement accuracy of the conductivity meter, and the like. It can be selected as appropriate. The concentration rate of bicarbonate ions can be selected, for example, by changing the flow rate of ultraviolet irradiation treatment water in the concentration chamber and the deionization chamber. The concentration ratio of bicarbonate ions can be calculated from the electrical conductivity of the concentrated water and the electrical conductivity of the drain water generated from the deionization chamber.
In the continuous regeneration type ion exchanger, the concentrated water enriched with bicarbonate ions is then sent to the electrical conductivity meter 3. Bicarbonate ions derived from the TOC component in ultrapure water are concentrated by the continuous regeneration type ion exchange device and have a high concentration, and therefore can be measured with high accuracy by an electric conductivity meter. The relationship between the amount of the TOC component in the sample water and the electrical conductivity of the concentrated water is obtained in advance using the concentration factor as a parameter, and a calibration curve is created. The concentration of the TOC component can be determined.
[0008]
In the present invention, any means for efficiently concentrating bicarbonate ions in water can be used without limitation, but a continuous regeneration type ion exchange apparatus can be particularly preferably used.
According to the underwater TOC monitor of the present invention, even in ultrapure water having a very low TOC concentration, bicarbonate ions generated in the water by decomposition of the TOC component are concentrated to accurately adjust the TOC concentration in the ultrapure water. Can be sought. By connecting the underwater TOC monitor of the present invention to the ultrapure water system piping and continuously collecting the sample water, the sample water is prevented from being contaminated by mixing organic substances, and the sample water flow in the monitor is stopped. The TOC concentration can be measured continuously without causing it to occur. Since the underwater TOC monitor of the present invention has a simple structure, it can be easily carried to the site and used easily without occupying a large space.
[0009]
【The invention's effect】
According to the underwater TOC monitor of the present invention, the electrical conductivity is measured by concentrating the bicarbonate ions generated by the decomposition of the TOC component, so that it is several μg / liter or less in ultrapure water used in the electronics industry and the like. The TOC component at a very low concentration can be measured easily and continuously with high sensitivity and high accuracy.
[Brief description of the drawings]
FIG. 1 is a system diagram of an underwater TOC monitor of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ultraviolet irradiation apparatus 2 Continuous regeneration type ion exchange apparatus 3 Electric conductivity meter 4 Ultraviolet lamp 5 Water flow path 6 Cathode 7 Anode 8 Anion exchange membrane 9 Cation exchange membrane 10 Concentration chamber 11 Deionization chamber 12 Electrode chamber 13 Mixed ion Exchange resin 14 Drain piping

Claims (1)

An apparatus for continuously measuring the TOC concentration in ultrapure water, an ultraviolet irradiation apparatus for decomposing TOC components in sample water, and a continuously regenerative ion that concentrates the electrolyte in the ultraviolet irradiation treated water to obtain concentrated water An underwater TOC monitor comprising an exchange device and an electric conductivity meter for measuring the electric conductivity of the concentrated water.

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