JP2002139429A - Dissolved-ozone concentration measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dissolved-ozone concentration measuring instrument which can quickly and accurately measure the concentrations of dissolved ozone and an interfering component contained in a sample solution and has a simple structure. SOLUTION: The reference spectrum storing section of an arithmetic processing section S2 for data stores a reference ozone spectrum ω (λ) and a reference organic-matter spectrum δ(λ). A concentration computing section computes the numerical values p and q which are most approximate to the ultraviolet spectrum μ (λ) of the sample solution measured by means of an ultraviolet spectrum measuring section S1 and [p.ω (λ)+q.δ (λ)] and uses p.Co and q.Cd as the ozone concentration and organic-matter concentration of the sample solution, respectively. A reference spectrum updating section appropriately computes the numerical value which is most approximate to the ultraviolet spectrum ν (λ) of a blank sample solution and q'.δ (λ) and performs blank calibration by updating the ultraviolet spectrum δ (λ) with ν(λ)/q'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring dissolved ozone concentration, and more particularly, to an advanced water purification system or the like for performing ozone treatment, which measures the concentration of dissolved ozone and the concentration of organic matter in a sample liquid containing ozone. The present invention relates to a dissolved ozone concentration measuring device capable of continuously measuring with high accuracy.

[0002]

2. Description of the Related Art Ozone has an extremely strong oxidizing or bactericidal activity and can be easily produced, and thus is widely used, for example, for purification of raw water taken from rivers and the like. However, the amount of dissolved ozone greatly varies depending on the amount of ozone gas supplied to water (or the amount of ozone gas generated) and the temperature of water. Ozone in water is in a chemically unstable state and easily decomposes. For this reason, when using ozone for purification of raw water, etc., it is necessary to constantly measure or monitor the dissolved ozone concentration.

[0003] The ozone concentration in water is measured, for example, by ultraviolet absorption spectroscopy. In the ultraviolet absorption analysis, first, the ultraviolet absorbance of a sample liquid containing ozone is measured. The ozone concentration is calculated from the ultraviolet absorbance of the sample liquid by utilizing the fact that there is a substantially proportional relationship between the ozone concentration and the ultraviolet absorbance in the ozone absorption band.

When the ozone concentration is measured by ultraviolet absorption analysis, if the sample solution contains a component (interfering component) whose absorption band is similar to the ozone absorption band, the measured ultraviolet absorbance becomes And the absorbed component caused by the interfering component. For this reason, it becomes impossible to accurately calculate the ozone concentration from the actually measured ultraviolet absorbance using the above proportional relationship.

More specifically, the maximum absorption band of ozone generally exists within a wavelength range of 250 to 260 nm, but the maximum absorption band of organic substances also exists generally within a wavelength range of 250 to 260 nm. Therefore, if an organic substance is contained in the sample liquid for which the ozone concentration is to be measured, the measured ultraviolet absorbance will be a value obtained by adding the absorption component due to the organic substance to the absorption component due to the dissolved ozone. Is higher than the true value, and an accurate ozone concentration cannot be obtained.

Therefore, for example, Japanese Patent Laid-Open No. 8-136526
In this publication, two absorbance measurement units are provided, one absorbance measurement unit measures the ultraviolet absorbance of a sample solution containing ozone and organic substances, and the other absorbance measurement unit removes ozone from the sample solution (blank). There is disclosed a dissolved ozone concentration measuring apparatus which measures the ultraviolet absorbance of a sample liquid) and calculates the ozone concentration from the difference between the two ultraviolet absorbances, that is, performs blank calibration.

[0007]

However, for example, in a conventional dissolved ozone concentration measuring apparatus disclosed in Japanese Patent Application Laid-Open No. 8-136526, a cell containing a sample liquid or a blank sample liquid, a photodetector, and the like are used. Since two light absorbance measurement units must be provided, there is a problem that the structure is complicated or large. There is also a problem that a measurement error may occur due to individual differences in characteristics of a cell or a detector between the two absorbance measurement units. Furthermore, every time the ozone concentration of the sample solution is measured, a blank sample solution must be prepared, the ultraviolet absorbance of the sample solution must be measured, and blank calibration must be performed. is there.

Japanese Patent Application Laid-Open No. 7-12720 discloses that
There is disclosed a dissolved ozone concentration measuring apparatus in which only one absorbance measurement unit is provided and a sample liquid and a blank sample liquid are measured by switching a sample liquid supply system to the absorbance measurement unit. However, even with this dissolved ozone concentration measurement device, every time the ozone concentration of the sample solution is measured, a blank sample solution must be prepared and blank calibration must be performed. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and can quickly and accurately measure the concentration of ozone in a sample liquid containing ozone and an interfering component, and the concentration of the interfering component. An object of the present invention is to provide a dissolved ozone concentration measuring device having a simple structure.

[0010]

Means for Solving the Problems A dissolved ozone concentration measuring apparatus according to the present invention, which has been made to solve the above problems, comprises:
(I) A dissolved ozone concentration measuring device for measuring the ozone concentration and / or the concentration of an interfering component in a sample liquid in which ozone and an interfering component that interferes with the measurement of ozone concentration are dissolved, (Ii) optical analysis means (for example, an ultraviolet absorbance measuring device) capable of measuring an ultraviolet spectrum indicating a relationship (correlation, correspondence) between ultraviolet absorbance and ultraviolet wavelength λ for an arbitrary sample;
i) The ultraviolet spectrum ω (λ) of the reference sample liquid having a constant ozone concentration Co and no interfering component and the ultraviolet spectrum δ (δ) of the reference sample liquid having a constant interfering element concentration Cd and no ozone λ) and (or
Holding and setting reference spectrum recording means;
v) The ultraviolet spectrum μ (λ) of any sample solution measured by the optical analysis means and (p · ω (λ) + q · δ)
(Λ)) and the numerical values p and q that best approximate (or match or match) with each other, and then p · Co is the ozone concentration of the sample liquid, and q · Cd is the concentration of the interfering component of the sample liquid. And a density calculating means.

Here, the calculation of the numerical values p and q is performed using, for example, the least square method. That is, the value of μ (λ) at a plurality of wavelength points and (p · ω (λ) + q · δ (λ))
Are calculated such that the sum of the squared values of the respective deviations from the value of becomes the minimum. The interfering component typically includes an organic substance. In addition, hydrogen peroxide is also an interfering component.

According to this dissolved ozone concentration measuring device, the ozone concentration and the concentration of an interfering component such as an organic substance or hydrogen peroxide can be accurately calculated (measured) only by measuring the ultraviolet spectrum of the sample solution once. be able to. When only the ozone concentration is required, the dissolved ozone concentration can be accurately measured without being affected by the interfering components. Further, when only the concentration of the interfering component is required, the concentration of the interfering component can be accurately measured without being affected by the dissolved ozone.

In this dissolved ozone concentration measuring apparatus,
Since only one optical analysis means such as an ultraviolet absorbance measuring device is required, the structure is simplified, the error factor is reduced, and the measurement accuracy is improved. Further, the blank calibration does not need to be performed every time the ultraviolet spectrum of the sample solution is measured, and may be appropriately performed, for example, about several times a day. For this reason, the time required for measuring the ozone concentration and the interfering component concentration is greatly reduced.

In the above dissolved ozone concentration measuring device,
After calculating the numerical value q ′ that makes the ultraviolet spectrum ν (λ) of the blank sample solution from which ozone is removed from the sample solution best (or matches or matches) with q ′ · δ (λ), (Λ) / q ′ is newly changed to ultraviolet spectrum δ (λ)
(That is, updating the ultraviolet spectrum δ (λ), that is, performing blank calibration) is preferably provided. In this manner, when the interfering component is an organic substance, the ultraviolet spectrum δ (λ) is updated to an optimum one according to a change in the kind, composition, property, etc. of the organic substance or the sample liquid. That is, blank calibration can be easily performed.

A predetermined wavelength λ ₀ of the ultraviolet spectrum ν (λ) of the blank sample liquid from which ozone has been removed from the sample liquid.
Numerical ν (λ ₀₎ which corresponds to the ultraviolet spectrum δ
After calculating a numerical value δ (λ ₀ ) of (λ) corresponding to the predetermined wavelength λ ₀ , (δ (λ ₀ ) / ν (λ ₀ )) · ν (λ) is newly added to the ultraviolet spectrum δ ( λ) may be provided. in this case,
Updating of the ultraviolet spectrum δ (λ), that is, blank calibration becomes extremely easy.

In the above-mentioned dissolved ozone concentration measuring device,
The blank sample solution can be prepared, for example, by the following method. (1) Ozone is removed by increasing the temperature of the sample solution. (2) The sample solution is brought into contact with a platinum catalyst to remove ozone. (3) Ultrasonic vibration is applied to the sample liquid to remove ozone. (4) The sample solution is left to stand naturally and waits for ozone to diffuse into the atmosphere. (5) The sample liquid is stirred by a stirrer to remove ozone. Note that a plurality of methods in (1) to (5) may be used in combination.

In the above-mentioned dissolved ozone concentration measuring apparatus, the ultraviolet spectrum is, for example, from 180 nm to 30 nm.
A continuous spectrum in the wavelength range up to 0 nm can be used. The ultraviolet spectrum is 180 nm
It may be composed of several to several tens of discrete absorbance data in the wavelength range from to 300 nm.

In the above-mentioned dissolved ozone concentration measuring apparatus, the optical analysis means may be, for example, a method in which the ultraviolet spectrum of the sample is measured by measuring the ultraviolet absorbance of the sample supplied into the sample cell using a pump or an aspirator. The ultraviolet absorbance measuring device described in the above can be used. Further, an ultraviolet absorbance measuring device that measures the ultraviolet spectrum of the sample by immersing the optical measurement probe in the sample and measuring the ultraviolet absorbance of the sample can also be used.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. As shown in FIG. 1, a dissolved ozone concentration measuring device for continuously or intermittently measuring the ozone concentration and the organic matter concentration in a sample liquid in which ozone and an organic substance (an obstruction component to ozone) are dissolved is substantially used. In addition, an ultraviolet spectrum measuring unit S1 (ultraviolet absorbance measuring device) capable of measuring an ultraviolet spectrum of an arbitrary sample (liquid)
And a data calculation processing unit S2 that performs various calculation processes described below on the ultraviolet spectrum data output from the ultraviolet spectrum measurement unit S1, calculates the ozone concentration and the organic matter concentration, and appropriately performs blank calibration. I have.

In the ultraviolet spectrum measuring section S1, the light source 1
(Continuous light) radiated from the light source is introduced into the interference filter 3 via the condenser lens 2. The interference filter 3 is an optical filter capable of extracting (passing) only ultraviolet light (monochromatic light) of a specific wavelength in the ultraviolet light emitted from the light source 1, and continuously or stepwise changing the wavelength of the extracted ultraviolet light. It can be changed.

The ultraviolet light of a specific wavelength extracted by the interference filter 3 is applied to the sample cell 5 via the first lens 4. The sample cell 5 holds a sample (a sample solution, a blank sample solution, etc.) whose ultraviolet spectrum is to be measured. Note that the sample is supplied into the sample cell 5 using, for example, a pump, an aspirator, or the like. For this reason, a part of the ultraviolet light having the specific wavelength applied to the sample cell 5 is absorbed by the sample. Then, the ultraviolet light of a specific wavelength transmitted through the sample cell 5 (sample) is introduced into the light receiving sensor 7 via the second lens 6, and is converted into an electric signal corresponding to the intensity of the ultraviolet light, and thus the ultraviolet light absorbance of the sample. . This electric signal is introduced to the data operation processing unit S2.

That is, in the ultraviolet spectrum measuring section S1, while the wavelength of the ultraviolet light irradiated to the sample cell 5 (sample) is continuously or stepwise changed by the interference filter 3, the sample liquid or the blank sample liquid or the like is changed. UV absorbance of the sample is detected.
, That is, the ultraviolet spectrum (ultraviolet absorbance spectrum) of the sample is measured. FIGS. 2 to 4 show ultraviolet spectra measured by the above-described method for a sample in which ozone is dissolved in pure water, a river water in which ozone is not dissolved, and a river water in which ozone is dissolved. An example is shown below.

Here, the wavelength range of the ultraviolet spectrum is the maximum absorption band of ozone (generally, 250 to 260 nm) and the maximum absorption band of organic substances (generally, 250 to 260 nm).
And is set to, for example, 180 to 300 nm. As the ultraviolet spectrum, a continuous spectrum in the above-mentioned wavelength range or a spectrum consisting of several to several tens discrete ultraviolet absorbance data is used. When the ultraviolet spectrum is a continuous spectrum, the interference filter 3 that can continuously change the wavelength of the ultraviolet light to be extracted is used. When the spectrum is a discrete spectrum, the wavelength of the ultraviolet light to be extracted is changed stepwise. What is necessary is just to use the interference filter 3 which can be used.

The ultraviolet spectrum measuring section S1 shown in FIG. 1 measures the ultraviolet absorbance of the sample held in the sample cell 5. However, the optical measuring probe is immersed in the sample. Then, the ultraviolet spectrum of the sample may be measured by measuring the ultraviolet absorbance of the sample.

Although not shown in detail, the data calculation processing section S2 includes a reference spectrum storage section, a density calculation section, and a reference spectrum update section. The reference spectrum storage unit (memory) of the data operation processing unit S2 is
The reference ozone spectrum ω (λ) and the reference organic substance spectrum δ (λ) are stored. Here, the reference ozone spectrum ω (λ) means an ultraviolet spectrum of a reference sample liquid having an ozone concentration of a constant value Co and containing no organic matter. The reference organic substance spectrum δ (λ) refers to an ultraviolet spectrum of a reference sample liquid in which the organic substance concentration is a constant value Cd and does not contain ozone. Note that the reference ozone spectrum ω (λ) is invariant regardless of the type and properties of the sample liquid. In contrast, the reference organic matter spectrum δ
For example, in the case of river water or the like, (λ) gradually changes with time according to changes in the type, properties, and the like of the sample liquid or organic substance.

The concentration calculation unit of the data calculation processing unit S2 firstly calculates the ultraviolet spectrum μ (λ) of an arbitrary sample liquid measured by the ultraviolet spectrum measurement unit S1 and [p · ω
(Λ) + q · δ (λ)] is calculated using the least squares method.
For example, a plurality of wavelength points (or wavelength ranges) λ ₁ , λ ₂ , λ
₃ ,... Λn, the value of μ (λ) and [p
.Omega. (. Lambda.) + Q.delta. (. Lambda.)], And calculate numerical values p and q such that the sum of the squares of the respective deviations is minimized. That is, p and q that best match Expression 1 are calculated. μ (λ) = p · ω (λ) + q · δ (λ) Equation 1 Then, p · Co is the ozone concentration of the sample liquid, and q · C
d is the organic matter concentration of the sample solution.

The reference spectrum updating unit of the data arithmetic processing unit S2 firstly determines the ultraviolet spectrum ν (λ) of the blank sample solution from which ozone has been removed from the sample solution and q ′ · δ (λ).
Is calculated using the least-squares method. Note that the least square method used here is basically the least square method used in the density calculation unit.
It is similar to multiplication. Then, ν (λ) / q ′ is newly set as the ultraviolet spectrum δ (λ), and the ultraviolet spectrum δ (λ) is updated. That is, blank calibration is performed.

[0028] In the reference spectrum update unit, values corresponding to a predetermined wavelength lambda ₀ of the ultraviolet spectrum [nu (lambda) of the blank sample solution [nu and (lambda _0), corresponding to a predetermined wavelength lambda ₀ of the ultraviolet spectrum [delta] (lambda) Δ (λ ₀ ) and [δ
(Λ ₀ ) / ν (λ ₀ )] · ν (λ) may be newly set as the ultraviolet spectrum δ (λ). In this case, updating of the ultraviolet spectrum δ (λ), that is, blank calibration becomes extremely easy.

The blank sample solution is prepared by increasing the temperature of the sample solution to decompose and remove dissolved ozone when performing blank calibration. That is, ozone dissolved in water is chemically unstable and decomposes relatively easily, but the decomposition rate increases as the temperature increases. Therefore, the temperature of the sample solution is raised to dissolve dissolved ozone quickly, and a blank sample solution is prepared in a short time. For example, as shown in FIG. 5, in the case of river water having a dissolved ozone concentration of about 6.7 ppm, the time required for the decomposition of dissolved ozone is about 180 when the water temperature is 25 ° C.
0 seconds, but about 250 seconds if the water temperature is 80 ° C.

The blank sample solution may be prepared by removing ozone from the sample solution using the following method. (A) A sample liquid is brought into contact with a platinum catalyst to decompose and remove ozone. (B) Ultrasonic vibration is applied to the sample liquid to decompose and remove ozone. (C) The sample liquid is allowed to stand naturally and wait for ozone to diffuse into the atmosphere. (D) The sample liquid is stirred by a stirrer to decompose and remove ozone. In addition, you may use combining each said method.

According to this dissolved ozone concentration measuring apparatus, the ozone concentration and the organic matter concentration can be accurately measured only by measuring the ultraviolet spectrum of the sample liquid once. Further, since only one ultraviolet spectrum measuring section S1 for measuring the ultraviolet absorbance of the sample is required, the structure of the dissolved ozone concentration measuring device is simplified, error factors are reduced, and the measuring accuracy is improved. Enhanced.

The blank calibration does not need to be performed each time the ultraviolet spectrum of the sample solution is measured, but may be appropriately performed, for example, several times a day. For this reason, the time required to measure the ozone concentration and the organic matter concentration is significantly reduced as compared with the conventional case. That is, with a simple structure, the ozone concentration and the organic substance concentration in the sample liquid containing ozone and the organic substance can be measured quickly and accurately.

In this embodiment, the case where the interfering component is an organic substance is described as an example. However, even when the interfering component is another substance, for example, hydrogen peroxide, the ozone concentration and the interfering component concentration are similarly determined. Can be measured quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a system configuration of a dissolved ozone concentration measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an ultraviolet spectrum of a sample in which ozone is dissolved in pure water.

FIG. 3 is a diagram showing an example of an ultraviolet spectrum of river water in which ozone is not dissolved.

FIG. 4 is a diagram showing an example of an ultraviolet spectrum of river water in which ozone is dissolved.

FIG. 5 is a graph showing the dependence of the time required to decompose dissolved ozone in river water on water temperature.

[Explanation of symbols]

S1: ultraviolet spectrum measuring unit, S2: data operation processing unit, 1: light source, 2: condensing lens, 3: interference filter, 4
.. A first lens, 5 a sample cell, 6 a second lens, 7 a light receiving sensor.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G059 AA01 BB04 BB05 CC08 CC12 DD05 EE01 EE12 FF07 FF08 GG00 HH03 HH06 JJ03 JJ11 KK01 LL04 MM10 MM14 NN01

Claims (15)

[Claims] 1. A dissolved ozone concentration measuring device for measuring the concentration of ozone and the concentration of an interfering component in a sample liquid in which ozone and an interfering component which interferes with the measurement of the concentration of ozone are dissolved. An optical analysis means capable of measuring an ultraviolet spectrum indicating the relationship between ultraviolet absorbance and ultraviolet wavelength λ; and an ultraviolet spectrum ω (λ) of a reference sample solution having an ozone concentration of a constant value Co and containing no interfering components. A reference spectrum recording means for recording an ultraviolet spectrum δ (λ) of a reference sample solution having a constant concentration Cd and no ozone, and an arbitrary sample solution measured by the optical analysis unit. UV spectrum μ (λ) and (p · ω (λ) + q · δ
(Λ)), and after calculating the numerical values p and q that are most similar to each other, p · Co is defined as the ozone concentration of the sample liquid,
And a concentration calculating means for determining the concentration of the interfering component in the sample liquid. 2. The dissolved ozone concentration measuring apparatus according to claim 1, wherein the concentration calculating means calculates the numerical values p and q using a least square method. 3. An ultraviolet spectrum ν (λ) of a blank sample solution from which ozone has been removed from the sample solution, and q ′ · δ.
After calculating a numerical value q ′ that best approximates (λ),
3. The dissolved ozone concentration measuring device according to claim 1, further comprising an interference component reference spectrum updating unit that newly sets ν (λ) / q ′ to an ultraviolet spectrum δ (λ). 4. A predetermined wavelength λ _{0 of} an ultraviolet spectrum ν (λ) of a blank sample solution from which ozone has been removed from the sample solution.
Numerical ν (λ ₀₎ which corresponds to the ultraviolet spectrum δ
After calculating a numerical value δ (λ ₀ ) of (λ) corresponding to the predetermined wavelength λ ₀ , (δ (λ ₀ ) / ν (λ ₀ )) · ν (λ) is newly added to the ultraviolet spectrum δ ( The dissolved ozone concentration measuring apparatus according to claim 1 or 2, further comprising means for updating an interference component reference spectrum to be λ). 5. The dissolved ozone concentration measuring apparatus according to claim 1, wherein the interfering component is an organic substance. 6. The dissolved ozone concentration measuring apparatus according to claim 1, wherein the interfering component is hydrogen peroxide. 7. The measurement of dissolved ozone concentration according to claim 3, wherein the blank sample solution is generated by removing the ozone by increasing the temperature of the sample solution. apparatus. 8. The dissolved ozone concentration according to claim 3, wherein the blank sample solution is generated by contacting the sample solution with a platinum catalyst to remove ozone. measuring device. 9. The dissolved ozone according to claim 3, wherein the blank sample liquid is generated by applying ultrasonic vibration to the sample liquid to remove ozone. Concentration measuring device. 10. The method according to claim 3, wherein the blank sample solution is generated by allowing the sample solution to stand naturally and waiting for ozone to diffuse into the atmosphere.
3. A dissolved ozone concentration measuring device according to any one of the above. 11. The concentration of dissolved ozone according to claim 3, wherein the blank sample solution is generated by stirring the sample solution with a stirrer to remove ozone. measuring device. 12. Each of the ultraviolet spectra has a wavelength of 180 n.
12. A continuous spectrum in a wavelength range from m to 300 nm.
3. A dissolved ozone concentration measuring device according to any one of the above. 13. Each of the ultraviolet spectra has a wavelength of 180 n.
The dissolved ozone concentration measuring apparatus according to any one of claims 1 to 11, comprising discrete light absorbance data of several to several tens of points in a wavelength range from m to 300 nm. 14. The method according to claim 1, wherein the optical analysis means measures an ultraviolet spectrum of the sample supplied to the sample cell by using a pump or an aspirator to measure an ultraviolet absorbance of the sample. Claim 1
14. The dissolved ozone concentration measuring apparatus according to any one of items 13 to 13. 15. The method according to claim 15, wherein the optical analysis means measures an ultraviolet spectrum of the sample by immersing an optical measurement probe in the sample and measuring an ultraviolet absorbance of the sample. Item 14. The dissolved ozone concentration measuring device according to any one of Items 1 to 13.