JP5468344B2 - Method for measuring concentration of water-soluble radical species in aqueous solution and apparatus for measuring concentration of water-soluble radical species - Google Patents

Description

  The present invention relates to a method for measuring a concentration of a water-soluble radical species in an aqueous solution and a water-soluble radical species concentration measuring apparatus.

In general, in the spectroscopic analysis using visible / ultraviolet rays, the absorption spectrum extends to the energy level of the electronic transition of the substance to be measured, and therefore involves a much larger energy change than the absorption spectrum of near infrared rays. The history of spectroscopic analysis using this fact is deep, and it has been applied to qualitative and quantitative analysis of various luminescent groups. Today, the spectrum of most chromophores is known. As described above, UV-visible spectroscopy has been widely used. However, from the viewpoint of spectroscopic analysis of solution components, it has been applied only to a solute having an intrinsic absorption band in a wavelength region of 200 nm to 800 nm. For example, nitrate ions (NO3 ²⁻ ) and nitrite ions (NO ²⁻ ) in precipitation are known to have absorption peaks at 201 nm and 210 nm, respectively, and detection and measurement using those wavelengths are performed. Yes.

  By the way, when the far-ultraviolet spectrum of water is observed, an absorption band due to electronic transition that appears on the lowest energy side appears in a wavelength region of 190 nm or less. FIG. 4 is a diagram showing an absorption spectrum of liquid water in the far infrared to far ultraviolet region. The first absorption band appearing in the far ultraviolet region is accompanied by an electronic transition in which an unpaired electron of an oxygen atom in a water molecule transitions from an unbonded n-orbital to an antibonded σ-orbital. It is called. It has already been well investigated that this band shifts sensitively in response to changes in the hydrogen bonding state between water molecules. For example, the absorption spectrum of water has a peak at a wavelength of 167.0 nm in a gas state, but the peak shifts to about 150 nm in a liquid. However, no attempt has been made so far to detect or measure substances dissolved in water using the absorption spectrum of the water itself. This is because when the amount of the component dissolved in water is very small, it is obvious that the main component is water, and it is obvious that the change in the absorption amount of the spectrum of the water itself due to the mixing of the trace component is negligibly small. .

  In the state where the charged dissolved component (for example, a cation such as sodium ion or potassium ion or an anion such as chloride ion or nitrate ion) is hydrated in water, Focusing on the fact that the energy required for the σ * transition shows changes inherent to the hydrated ions, the state of changes in the n → σ * transition spectra of water for various hydrated ions was systematically investigated. As a result, in the state where the dissolved component is hydrated in water, the electric field of the hydrated ion affects the bottom of the absorption peak near 150 nm to 160 nm due to the n → σ * transition (ordinary spectroscopy of 180 nm to 210 nm). We have already invented an aqueous solution measurement method using this, ascertaining that the intensity, position, and band width of the absorption band appearing in the region measurable by the apparatus are very sensitive to hydrogen bonding and hydration of water. (For example, refer to Patent Document 1).

Japanese Patent Laying-Open No. 2005-214863

  On the other hand, in recent years, the measurement of the concentration of water-soluble radical species (for example, hydroxyl radical) in an aqueous solution has become indispensable in fields such as semiconductor cleaning processes, food sterilization cleaning, and environmental pollutant decomposition treatment. . And the electron spin resonance (ESR: Electron Spin Resonance) has generally been utilized for the measurement of such water-soluble radical species concentration. However, in ESR, since water-soluble radical species (particularly hydroxyl radicals) have an extremely short lifetime, it was necessary to perform measurement after adding a spin trap agent. In addition, a method using fluorescence deactivation is also used, but in such a method, it is necessary to add a molecule to be a fluorescent probe. Therefore, none of the existing methods for measuring the concentration of water-soluble radical species as described above can be said to be a method of measuring an aqueous solution to be measured as it is by adding a spin trap agent or the like. On the other hand, it is not allowed to mix an additive into a cleaning solution for measurement in a cleaning process of food or semiconductor. Therefore, the advent of a method for measuring the water-soluble radical species concentration in a non-invasive and real-time manner without pretreatment such as mixing of additives at the place where the water-soluble radical species is generated has been desired.

  The present invention has been made in view of the above-described problems, and the object thereof is to measure the concentration of water-soluble radical species in a non-invasive and real-time manner without pretreatment such as mixing of additives at the place of occurrence. An object of the present invention is to provide a method for measuring a water-soluble radical species concentration in an aqueous solution and a water-soluble radical species concentration measuring apparatus.

  In order to achieve the above object, the present inventor has diligently studied a method for measuring the concentration of water-soluble radical species in an aqueous solution. As a result, it has been found that the far-infrared spectrum intensity of the aqueous solution is changed by the generation of water-soluble radical species as well as the hydration of the salt, and the present invention has been completed.

  That is, the method for measuring the concentration of the water-soluble radical species in the aqueous solution of the present invention is the correlation between the concentration of the water-soluble radical species in the aqueous solution and the absorption characteristics measured at one or more wavelengths within the range of 140 to 210 nm of the aqueous solution. The water-soluble radical species concentration in the aqueous solution is quantified based on the property.

  According to the above configuration, since the light absorption characteristics of the aqueous solution may be directly measured, the concentration of the water-soluble radical species can be measured without changing the state of the aqueous solution to be measured, such as by adding a spin trap agent or the like. . Moreover, since it is only necessary to measure the light absorption characteristics of the aqueous solution at one or more wavelengths within the range of 140 to 210 nm, the aqueous solution can be measured non-invasively and in real time without taking out the aqueous solution from the system. . The correlation is preferably a correlation between the concentration of the water-soluble radical species in the aqueous solution and the light absorption characteristics measured at one or more wavelengths within the range of 150 to 210 nm of the aqueous solution, and the 155 to 185 nm of the aqueous solution. The correlation with the light absorption characteristics measured at one or more wavelengths within the above range is more preferable. In this specification, the far ultraviolet region refers to an ultraviolet region having a wavelength shorter than 280 nm and longer than 100 nm. In the present invention, the water-soluble radical species refers to at least one of water-soluble radical species including a hydroxyl radical, a superoxide, a hydroperoxyl radical, and a hydrogen radical.

  The method for measuring the concentration of the water-soluble radical species in the aqueous solution of the present invention is the calibration of the light absorption characteristics and the water-soluble radical species concentration at one or more wavelengths within the range of 140 to 210 nm of the aqueous solution containing the water-soluble radical species. The absorption characteristic of the aqueous solution containing the water-soluble radical species is measured in advance at one or more wavelengths, and the concentration of the water-soluble radical species in the aqueous solution is determined using the calibration curve from the obtained absorption characteristic data. It is characterized by quantifying.

  According to the above configuration, since the light absorption characteristics of the aqueous solution may be directly measured, the concentration of the water-soluble radical species can be measured without changing the state of the aqueous solution to be measured, such as by adding a spin trap agent or the like. . In addition, using a calibration curve prepared in advance, the concentration of water-soluble radical species in the aqueous solution is measured using the calibration curve from the obtained light absorption characteristics. Non-invasive and real-time measurement is possible.

  In the said structure, it is preferable to perform the measurement of the said light absorption characteristic continuously and to perform fixed_quantity | quantitative_assay of water-soluble radical seed | species concentration.

  In addition, the water-soluble radical species concentration measuring apparatus of the present invention includes an absorption characteristic measuring means for measuring the absorption characteristics of an aqueous solution to be measured at one or more wavelengths within a range of 140 to 210 nm, and a water-soluble radical species in the aqueous solution. Based on the light absorption characteristics measured by the light absorption characteristic measurement means based on the concentration and the correlation between the light absorption characteristics of the aqueous solution measured at one or more wavelengths within the range of 140 to 210 nm, the water-soluble radicals of the aqueous solution to be measured And quantification means for quantifying the seed concentration.

  According to the above configuration, since the light absorption characteristics of the aqueous solution are directly measured, the concentration of the water-soluble radical species can be measured without changing the state of the aqueous solution to be measured, such as adding a spin trap agent. In addition, since the light absorption characteristics of the aqueous solution at one or more wavelengths within the range of 140 to 210 nm are measured, the aqueous solution can be measured non-invasively and in real time without taking out the aqueous solution from the system.

  Moreover, the water-soluble radical species concentration measuring apparatus of the present invention determines a calibration curve between the light absorption characteristics and the water-soluble radical species concentration at one or more wavelengths within the range of 140 to 210 nm of an aqueous solution containing a water-soluble radical species. A calibration curve determining means, a measuring means for measuring the light absorption characteristics of the aqueous solution containing the water-soluble radical species to be measured at the one or more wavelengths, and using the calibration curve from the obtained light absorption characteristics data, And a quantitative means for quantifying the concentration of water-soluble radical species in the aqueous solution.

  According to the above configuration, since the light absorption characteristics of the aqueous solution are directly measured, the concentration of the water-soluble radical species can be measured without changing the state of the aqueous solution to be measured, such as adding a spin trap agent. In addition, using a calibration curve prepared in advance, the concentration of water-soluble radical species in the aqueous solution is measured using the calibration curve from the obtained light absorption characteristics. Non-invasive and real-time measurement is possible.

  In the above configuration, the measuring means continuously measures the light absorption characteristics of the aqueous solution containing the water-soluble radical species to be measured at the one or more wavelengths, and the quantifying means is based on the obtained light absorption characteristic data. It is preferable to continuously quantify the water-soluble radical species concentration in the aqueous solution to be measured using the calibration curve.

  According to the present invention, a method for measuring the concentration of a water-soluble radical species in an aqueous solution capable of measuring the water-soluble radical species concentration in a non-invasive and real-time manner without pretreatment such as mixing of additives at the place of occurrence thereof, and A water-soluble radical species concentration measuring device can be provided.

It is a figure which shows the difference of the far ultraviolet absorption spectrum of water before and behind hydroxyl radical generation. It is a block diagram of the attenuated total reflection type far ultraviolet spectrometer used for the measurement of the hydroxyl radical density | concentration in aqueous solution. It is a figure which shows typically the measurement part shown in FIG. It is a figure which shows the absorption spectrum of the water of the liquid of a far infrared region to a far ultraviolet region.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following, a method for measuring the concentration of hydroxyl radicals in an aqueous solution as a water-soluble radical species and a hydroxyl radical concentration measuring device will be described. However, the present invention is not limited to other water-soluble radical species (for example, superoxide, The same applies to hydroperoxyl radicals, hydrogen radicals and the like. Furthermore, the present invention can be applied not only to water-soluble radical species but also to measurement of the concentration of, for example, singlet oxygen that affects the hydrogen bonding and hydration of water and the concentration measuring device thereof. .
As shown in FIG. 4, water has an absorption spectrum derived from the n → σ * transition in the vicinity of 150 nm in the liquid state. This absorption spectrum correlates with the concentration of hydroxyl radicals dissolved in water. An example will be described below with reference to FIG.

  FIG. 1 is a diagram showing the difference in the far ultraviolet absorption spectrum of water before and after the generation of hydroxyl radicals. In FIG. 1, the difference in absorbance between water obtained by dissolving 50 ppm of ozone gas in pure water (hereinafter also referred to as “ozone water”) and water containing hydroxyl radicals is represented by three wavelengths of 167 nm, 168 nm, and 169 nm. Is shown. The water containing the hydroxyl radical is water obtained by generating hydroxyl radicals by irradiating the ozone water with ultraviolet rays. As shown in FIG. 1, the absorbance of ozone water increases after irradiation with ultraviolet light, that is, according to an increase in the concentration of hydroxyl radicals. In the present embodiment, 1.2 ppm (70.6 μM) of hydroxyl radicals are generated by irradiation with ultraviolet rays, and JIS-R1704 (2007) “Fine ceramics-Photocatalytic material by active oxygen generation ability measurement. It was confirmed based on the “Water purification performance test method”.

  Thus, the hydroxyl radical concentration in the aqueous solution and the absorbance at wavelengths of 167 nm, 168 nm, and 169 nm of the aqueous solution have a correlation. Therefore, a calibration curve can be obtained by measuring the absorbance at one wavelength of 167 nm, 168 nm, and 169 nm for a plurality of hydroxyl radical concentrations. As a result, the absorbance of the aqueous solution containing the hydroxyl radical to be measured can be measured at the wavelength, and the hydroxyl radical concentration in the aqueous solution can be quantified using the calibration curve from the obtained absorbance data. Moreover, it is possible to obtain a more accurate calibration curve by measuring the absorbance at two or more wavelengths of 167 nm, 168 nm, and 169 nm for a plurality of hydroxyl radical concentrations.

  The difference in the far ultraviolet absorption spectrum of water before and after hydroxyl radical generation shown in FIG. 1 was measured using an attenuated total reflection type far ultraviolet spectroscope shown below. Therefore, next, the attenuated total reflection type far-ultraviolet spectroscopic apparatus used in this measurement will be described.

  FIG. 2 is a block diagram of an attenuated total reflection far-ultraviolet spectroscopic apparatus used for measuring the hydroxyl radical concentration in an aqueous solution. FIG. 3 is a diagram schematically showing the measurement unit shown in FIG. The attenuated total reflection type far-ultraviolet spectroscopic device 10 used in the present embodiment is capable of measuring the absorption spectrum of water in the far ultraviolet region using the total reflection attenuation absorption method. Specifically, for example, those described in JP2007-279025A and JP2008-224240A can be used. Therefore, hereinafter, the attenuated total reflection far-ultraviolet spectroscopic device 10 will be described within a range necessary to describe the present invention.

  As shown in FIG. 2, the attenuated total reflection far-ultraviolet spectroscopic device 10 includes a measurement unit 30 and a control unit 40. The control unit 40 includes a central processing unit and a memory, and performs information processing and operation control of the attenuated total reflection far-ultraviolet spectroscopic device 10 as a whole. As shown in FIG. 3, the measurement unit 30 is attached to a quartz pipe 14 that is in contact with water 12 (ozone water 12), and is made of a total reflection attenuation probe 16 made of quartz material that is arranged so as to be in contact with the pipe 14. A projection optical system 18 that irradiates far ultraviolet light generated by a light source (not shown) to the interface of the total reflection attenuation probe 16 at an incident angle larger than the critical angle, and reflection that is totally reflected from the interface of the total reflection attenuation probe 16. And a light receiving optical system 20 that receives light with a photodetector (not shown).

  A 30 W deuterium lamp was used as the light source constituting the light projecting optical system 18. In addition, as a photodetector constituting the light receiving optical system 20, a photomultiplier tube having no sensitivity at a wavelength of 200 nm or more was used.

  As the total reflection attenuation probe 16, a probe made of quartz was used. Thereby, a measurement wavelength range can be made into the range of 150-210 nm.

  As a light source of the ultraviolet light 22 for ozone decomposition, a 200 W mercury xenon lamp was used, and the ultraviolet light 22 was applied to the ozone water 12 from the total reflection attenuation probe 16 side through the total reflection attenuation probe 16 and the pipe 14. At this time, in order to capture the spectral change with high sensitivity, the ultraviolet irradiation was blinked at 5 kHz, and only the signal change synchronized with the blinking was amplified and observed. And the difference of the time of ultraviolet irradiation (at the time of hydroxyl radical generation) and the time of non-irradiation (at the time of hydroxyl radical non-generation) was calculated | required. From the above, the difference in the far ultraviolet absorption spectrum of water before and after hydroxyl radical generation shown in FIG. 1 was obtained.

In the above description, when measuring the absorbance of the aqueous solution to be measured, the measuring unit 30 functions as a light absorption characteristic measuring unit. In addition, when measuring the absorbance at the above wavelengths for a plurality of hydroxyl radical concentrations to determine a calibration curve, the control unit 40 functions as a calibration curve determination means. Further, when the hydroxyl radical concentration of the aqueous solution to be measured is quantified from the measured absorbance of the aqueous solution to be measured, the control unit 40 functions as a quantification unit. Further, when the absorbance at the above-mentioned wavelength of the aqueous solution to be measured is measured, and the hydroxyl radical concentration of the aqueous solution to be measured is quantified from the measured absorbance, the attenuated total reflection far-ultraviolet spectroscopic device 10 is the hydroxyl group of the present invention. Functions as a radical concentration measuring device.

  In addition, if the absorbance is measured continuously (continuously or intermittently) and the hydroxyl radical concentration is continuously quantified, it is possible to monitor the continuous change of the hydroxyl radical concentration. .

  In the above-described embodiment, a calibration curve is obtained by measuring the absorption spectrum intensity at a specific wavelength (at least one wavelength of 167 nm, 168 nm, and 169 nm), and this calibration curve is used in an aqueous solution. The case where the hydroxyl radical concentration was measured was described. However, in the present invention, the hydroxyl radical concentration in the aqueous solution is measured based on the correlation between the hydroxyl radical concentration in the aqueous solution and the absorption spectrum intensity at one or more wavelengths within the range of 140 to 210 nm of the aqueous solution. If it does, it is not limited to this example. In the present invention, for example, the measurement of the hydroxyl radical concentration in an aqueous solution based on the correlation between the amount of peak movement of the absorption spectrum derived from the n → σ * transition of water and the hydroxyl radical concentration in the aqueous solution. Also good. The correlation between the amount of movement of the absorption spectrum peak and the hydroxyl radical concentration in the aqueous solution is not particularly limited. For example, a plurality of types of hydroxyl radical-containing water whose concentrations are known in advance and the peak of the absorption spectrum Can be obtained by measuring.

  In the present invention, for example, the hydroxyl radical concentration in the aqueous solution may be measured based on the correlation between the band width of the absorption spectrum and the hydroxyl radical concentration in the aqueous solution.

  The embodiment of the present invention has been described above, but only specific examples are illustrated, and the present invention is not particularly limited. The specific configuration of each unit and the like can be appropriately changed. The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

10 Attenuated total reflection type far ultraviolet spectrometer 12 Water (ozone water)
14 piping 16 total reflection attenuation probe 18 light projecting optical system 20 light receiving optical system 30 measuring unit 40 control unit

Claims (6)

Quantifying the hydroxyl radical concentration in the aqueous solution based on the correlation between the hydroxyl radical concentration in the aqueous solution and the light absorption characteristics measured at one or more wavelengths within the range of 155 to 185 nm of the aqueous solution. A method for measuring the concentration of water-soluble radical species in an aqueous solution. A calibration curve between the absorption characteristics at one or more wavelengths in the range of 155 to 185 nm of the aqueous solution containing hydroxyl radicals and the hydroxyl radical concentration is determined in advance,
Measuring the absorption characteristics of an aqueous solution containing hydroxyl radicals at the one or more wavelengths;
A method for measuring the concentration of water-soluble radical species in an aqueous solution, wherein the concentration of hydroxyl radicals in the aqueous solution is quantified using the calibration curve from the obtained light absorption characteristic data. The method for measuring the concentration of water-soluble radical species in an aqueous solution according to claim 1 or 2, wherein the measurement of the light absorption characteristic is continuously performed and the determination of the hydroxyl radical concentration is continuously performed. An absorption characteristic measuring means for measuring the absorption characteristic of an aqueous solution to be measured at one or more wavelengths within a range of 155 to 185 nm;
Based on the light absorption characteristics measured by the light absorption characteristic measuring means based on the correlation between the hydroxyl radical concentration in the aqueous solution and the light absorption characteristics measured at one or more wavelengths within the range of 155 to 185 nm of the aqueous solution, An apparatus for measuring the concentration of water-soluble radical species, comprising a quantitative means for determining the hydroxyl radical concentration of an aqueous solution of A calibration curve determining means for determining a calibration curve between the absorption characteristics at one or more wavelengths in the range of 155 to 185 nm of the aqueous solution containing hydroxyl radicals and the hydroxyl radical concentration;
Measuring means for measuring the light absorption characteristics of an aqueous solution containing a hydroxyl radical to be measured at the one or more wavelengths;
A water-soluble radical species concentration measuring apparatus comprising: a quantifying means for quantifying the hydroxyl radical concentration in the aqueous solution to be measured using the calibration curve from the obtained light absorption characteristic data. The measurement means continuously measures the light absorption characteristics of an aqueous solution containing a hydroxyl radical to be measured at the one or more wavelengths,
The water-soluble radical species according to claim 4 or 5, wherein the quantitative means continuously quantifies the hydroxyl radical concentration in the aqueous solution to be measured using the calibration curve from the obtained light absorption characteristic data. Concentration measuring device.

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