JP2005134135A - Apparatus for measuring concentration of ozone water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for measuring the concentration of ozone water, which stably measures the concentration of dissolved ozone. <P>SOLUTION: A sensor 3 provided with a pair of electrodes 3a and 3b constituted of dissimilar metals having different ionization tendencies is immersed in a liquid to be measured to generate an electromotive force corresponding to the concentration of the dissolved ozone between the electrodes. In this case, by executing the manual operation of speedily shaking the sensor 3 in the state immersed in the liquid to be measured, the electromotive force is outputted in a rippling state. Its output voltage is supplied for a peak hold part 12 via a voltage amplification part 11 to acquire a peak value. On the basis of the peak value, the lighting of an indicator 6c by a LED in a concentration display part 6 is controlled to display the concentration of the dissolved ozone. Since it is known that the peak value indicates an approximately constant value to the concentration of dissolved ozone, stable concentration values of dissolved ozone are acquired even in the case that the sensor part is vibrated by manual shaking. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ozone water concentration measuring device for measuring the dissolved ozone concentration of dissolved ozone (water in which ozone is dissolved), and more specifically, by directly immersing electrodes made of dissimilar metals having different ionization tendencies in a liquid to be measured. The present invention relates to a so-called bare electrode type ozone water concentration measuring apparatus using a galvanic cell method for obtaining an electromotive force.

  Conventionally, as a method for measuring the ozone concentration of ozone water, an ultraviolet absorption method and a titration method (KI method) are used as the most reliable ones. However, measuring devices employing these methods are extremely expensive, and recently, a measuring device using an electrode-type sensor that has a simple mechanism, quick response, and is capable of continuous measurement has attracted attention as being easily usable. ing.

  As an ozone water concentration measuring device using an electrode type sensor, there are proposed a diaphragm type in which ozone water and a pair of electrodes are partitioned by an ozone permeable film, and a bare electrode type in which the electrode is directly immersed in ozone water. . The latter bare electrode type comprises a pair of electrodes made of a combination of specific dissimilar metals, and an electromotive force corresponding to the ozone concentration can be obtained between both electrodes by immersing the pair of electrodes in contact with each other in ozone water. It is something that uses that.

This is the application of the so-called galvanic cell principle (galvanic cell method) in which electromotive force is generated by immersing a pair of electrodes with different ionization tendency in a solution at a predetermined interval. Regarding the ozone water concentration measuring apparatus, for example, Patent Document 1 shown below is shown.
JP-A-8-304334

  By the way, in order to use the above-described galvanic cell method, as described above, two or more kinds of metals or metal compounds having different ionization tendencies may be used as described above, but the metal constituting the electrode is oxidized by ozone. Therefore, the maintenance that the surface of the electrode must always be polished is necessary. Therefore, in an embodiment to be described later, gold (Au) is used for one of the pair of electrodes, and silver silver chloride (Ag / AgCl) is used for the other. Thereby, it is possible to suppress the electrode surface from being changed to oxide by ozone, and to obtain a stable measurement result due to the unique operational effects of the present invention described later.

When the basic principle of the galvanic cell method described above is used, an electromotive force obtained by the following equation 1 is generally used.
E = −ΔG / nF (Formula 1)
Where E: electromotive force
ΔG: Gypsum energy
n: Number of electrons related to the reaction
F: Faraday constant

However, as described above, in the measuring apparatus described later using a sensor electrode using gold on one side and silver silver chloride on the other side, the electromotive force generated between the sensors corresponding to the dissolved ozone concentration in a predetermined range is The following equation 2 can be obtained.
E = k · f1 (ν) · T · f2 (Cl -) · f3 (R) · C ...... ( Equation 2)
Where E: electromotive force
k: Density conversion coefficient
f1 (ν): Function of sensor moving speed
T: Water temperature
f2 (Cl ^-): function of chlorine ion concentration
f3 (R): Function of interelectrode resistance
C: Ozone concentration

  As shown in Equation 2 above, it is understood that the dissolved ozone concentration can be calculated by setting the sensor moving speed, the water temperature, and the chlorine ion concentration to predetermined conditions and measuring the electromotive force. Here, considering the relation between the sensor moving speed and the electromotive force, when the sensor is immersed in dissolved ozone water in a stationary state, the ozone near the electrode surface reacts with the sensor, and the ozone instantly changes. Since it is decomposed, polarization occurs and the electromotive force decreases. Therefore, a dissolved ozone measuring device using the galvanic cell method must take measures such as vibrating the electrode in order to constantly supply new ozone to the electrode surface.

  FIG. 1 shows the relationship between the sensor moving speed and the sensor electromotive force when the dissolved ozone concentration is constant. As can be understood from the characteristics shown in FIG. 1, it can be seen that the electromotive force reaches its peak when the sensor moving speed exceeds a certain level. Therefore, in the conventional ozone water concentration measuring apparatus disclosed in Patent Document 1, a sensor starter is provided by mechanically vibrating (reciprocating) or rotating the sensor electrode at a constant speed. A device to stabilize electric power is made.

  However, providing a mechanism such as mechanically vibrating (reciprocating) or rotating the sensor electrode at a constant speed is unavoidable due to an increase in cost due to the mechanism and a drive unit for driving the mechanism. Problems such as the need for maintenance of the mechanism and the drive unit remain.

  The present invention has been made paying attention to the above-mentioned problems, and by removing the mechanism for driving and rotating the sensor electrode and its driving unit, the dissolved ozone concentration within the practical level can be easily obtained. It is another object of the present invention to provide an ozone water concentration measuring apparatus that can measure stably and stably.

  The ozone water concentration measuring apparatus according to the present invention, which has been made to solve the above-mentioned problems, is a sensor comprising a pair of electrodes formed of a dissimilar metal and immersed in a liquid to be measured. And a peak hold means for detecting and holding the peak value of the electromotive force generated between the electrodes in the sensor, and a concentration display for displaying the dissolved ozone concentration corresponding to the voltage value held by the peak hold means And a means.

  In this case, as described in claim 2, a resistor for adjusting linearity of the electromotive force with respect to the dissolved ozone concentration of the liquid to be measured is preferably connected between the pair of electrodes constituting the sensor. . In addition, as described in claim 3, gold (Au) is used as one electrode material constituting the sensor, and silver silver chloride (Ag / AgCl) is used as the other electrode material. desirable.

  According to the ozone water concentration measuring apparatus described above, the peak value of the electromotive force generated between the electrodes constituting the sensor is held, and the dissolved ozone concentration is displayed based on this hold value. The technical support provided with the peak hold means as described above is based on the technical basis described below. That is, the inventor of the present case has studied variously whether or not the electromotive force can be stably measured when the sensor unit immersed in the liquid to be measured is vibrated by hand shaking. However, it has been found that it is difficult to maintain a constant sensor moving speed according to the hand-shaking method, and as a result, a phenomenon in which a wave is applied to the electromotive force occurs. An example is shown in FIG. 2, where the horizontal axis is time (t) and the vertical axis is electromotive force (E).

  As shown in FIG. 2, although the phenomenon of pulsing the electromotive force occurs according to the hand shaking method, further investigations have been made focusing on the peak value of the electromotive force. On the other hand, it was found to show an almost constant value. Therefore, by obtaining the peak value of the electromotive force generated between the electrodes constituting the sensor as described above, it is possible to obtain a stable dissolved ozone concentration value even when the sensor unit is vibrated by hand shaking. It has been verified that this is possible.

  According to the ozone water concentration measuring apparatus according to claim 1 described above, a stable dissolved ozone concentration value can be obtained by a hand-waving method. Therefore, as in the conventional configuration shown in Patent Document 1, a sensor is used. The mechanism for mechanically vibrating or rotating the electrode and its driving unit can be removed. Therefore, it is possible to easily and stably measure the dissolved ozone concentration in a practical range at a low cost.

  Moreover, according to the measuring apparatus of Claim 2, since it is set as the structure which connected the resistor which can adjust the linearity of the electromotive force with respect to dissolved ozone concentration between a pair of electrodes which comprise a sensor, In addition to the effects described above, it is possible to obtain linearity that is convenient for signal processing when the density display unit is driven.

  Furthermore, according to the measuring apparatus of Claim 3, it can suppress that the electrode material which comprises a sensor is oxidized by ozone by selecting the combination of the above-mentioned raw material as an electrode material which comprises a sensor. it can. Thereby, stability of a measurement result can be ensured over a long period of time, and a highly reliable measurement apparatus can be provided.

  Hereinafter, an ozone water concentration measuring apparatus according to the present invention will be described based on embodiments shown in the drawings. FIG. 3 shows an external configuration example of the measuring apparatus according to the present invention. As shown in FIG. 3, this ozone water concentration measuring apparatus has a rectangular parallelepiped gripping portion 1 that is rounded as a whole, a rod-shaped member 2 that extends from the end in the longitudinal direction, and the rod-shaped member. The sensor unit 3 is attached to the tip of the member 2. On one side of the grip portion 1, in order from the upper part to the lower part, a power lamp 4 using an LED indicating the operation state of the apparatus, a measurement button 5 for executing a measurement operation of the dissolved ozone concentration, and a plurality of LEDs Is arranged in the vertical direction.

  When using the measuring apparatus having the external configuration shown in FIG. 3, a predetermined amount of ozone water as a liquid to be measured is taken in a container such as a beaker (not shown), and the sensor unit 3 is moved to ozone while pressing the measurement button 4. Soak in water. Then, by performing an operation (for example, about 4 reciprocations per second) of shaking the sensor unit 3 in ozone water, the LED is lit on the concentration display unit 6. And the molten ozone density | concentration in ozone water can be read by the lighting state of LED in this density | concentration display part 6. FIG.

  FIG. 4 is a block diagram showing an outline of the electrical internal configuration of the measuring apparatus shown in FIG. As already described, the sensor portion indicated by reference numeral 3 is provided with a pair of electrodes 3a and 3b, which act as a galvanic cell by being immersed in the liquid to be measured. In this embodiment, gold (Au) is used as one electrode material (working electrode material) constituting the sensor unit 3, and silver / silver chloride (Ag / AgCl) is used as the other electrode material (counter electrode material). It is used. By this combination, it is possible to generate electromotive force relatively efficiently with ozone water, and to suppress oxidation of each electrode material by ozone.

  A resistor R1 is connected between the pair of electrodes 3a and 3b constituting the sensor section 3 described above. Although the action of this resistor will be described in detail later, the range of the linearity of the electromotive force with respect to the dissolved ozone concentration can be adjusted by selecting the resistance value of this resistor R1. The both-end voltage (electromotive force) provided by the sensor unit 3 is supplied to the inverting input terminal and the non-inverting input terminal of the operational amplifier 11a functioning as the signal amplification unit 11, respectively.

  The output amplified by the signal amplification unit 11 is supplied to a peak hold unit 12 as a peak hold unit. The peak hold unit 12 includes a peak detection circuit 12a including a diode (not shown) for half-wave rectifying the output voltage from the signal amplification unit 11, a capacitor C1 for holding a peak value obtained by the peak detection circuit 12a, And a high-resistance resistor R2 for gradually discharging the voltage across the capacitor C1. Then, the peak value held by the capacitor C1 is supplied to the concentration display unit 6 through impedance conversion or the like.

  In addition, the above-described peak hold unit 12 captures the peak value of the electromotive force generated by immersing the sensor unit 3 in ozone water and shaking as already described. For example, the electromotive force (E shown in FIG. ) Function to detect the peak value.

  The density display unit 6 is provided with an A / D converter 6a that receives a hold voltage supplied from the peak hold unit 12 and converts the hold voltage into digital data, and a digital signal provided by the A / D converter 6a. The data is configured to be supplied to the LED driver 6b. The LED driver 6b is connected to a display body 6c of a plurality of LEDs, and the LED driver 6b controls the number of lighting of the display body 6c corresponding to the hold voltage supplied from the peak hold unit 12 as a result. Acts like Therefore, as described above, the molten ozone concentration in the ozone water can be read from the number of lighting of the display body 6c.

  FIG. 5 shows the relationship between the dissolved ozone concentration and the electromotive force when the resistance value of the resistor R1 connected between the pair of electrodes 3a and 3b constituting the sensor unit 3 is used as a parameter. is there. According to this, when the resistance value between the electrodes is large (for example, no resistance = OPEN), the electromotive force reaches a peak at a low molten ozone concentration. On the other hand, it can be seen that the level of electromotive force decreases as the resistance value decreases, but the linearity of electromotive force with respect to the dissolved ozone concentration, that is, linearity is improved. Therefore, if an appropriate resistance value is selected from the balance between the measurement range of the concentration measuring apparatus and the amplification error, linearity convenient for the concentration display process can be obtained.

  In addition, as understood from the above-described equation 2, in the ozone water concentration measurement apparatus according to this embodiment, the electromotive force increases as the water temperature increases. For example, the concentration is compensated by temperature compensation using a thermistor or the like. The display value can be corrected. There is also a method of limiting the measurement water temperature range so that the measurement error falls within the error range of the product specification. In this case as well, more accurate concentration measurement can be performed by recalibrating with the measured water temperature.

  Moreover, as understood from the above-described equation 2, the electromotive force depends on the chlorine ion concentration function. The sensor 3 used in the measuring apparatus according to this embodiment has almost no electromotive force in pure water-based dissolved ozone water, and tap water-based dissolved ozone water has reached a certain level (for example, about 3 ppm). As a result of experiments, it has been found that The reason for this is that gold is used as the working electrode material of the sensor and a silver-silver chloride electrode is used as the counter electrode material, but the electromotive force generated between the electrodes is hindered by the electrical conductivity of water and the chlorine ion concentration. it is conceivable that.

  Therefore, in order to obtain a stable electromotive force using the above-described ozone water concentration measuring device, if a necessary amount of saturated saline solution or the like is measured after being dropped into the liquid to be measured, the electromotive force is stabilized. The range in which the dissolved ozone concentration can be measured can be expanded. In addition, the measurable range of the measurement liquid water quality can be expanded.

It is the characteristic view which showed the relationship between the sensor moving speed and the sensor electromotive force when the dissolved ozone concentration is constant. It is the characteristic view which showed the generation | occurrence | production state of the electromotive force at the time of vibrating a sensor part by hand gesture. It is the perspective view which showed the example of an external appearance structure of the ozone water concentration measuring apparatus concerning this invention. It is a block diagram which shows the outline | summary of the electrical internal structure of the measuring apparatus shown in FIG. It is the characteristic view which showed the relationship between the dissolved ozone density | concentration when using the resistance value of the resistor connected between a pair of electrodes which comprise a sensor part as a parameter, and an electromotive force.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gripping part 2 Rod-shaped member 3 Sensor part 3a, 3b Electrode 4 Power lamp 5 Measurement button 6 Concentration display part 6a A / D converter 6b LED driver 6c Display body 11 Signal amplification part 11a Operational amplifier 12 Peak hold part 12a Peak detection circuit

Claims (3)

  A sensor comprising a pair of electrodes formed of a dissimilar metal and immersed in the liquid to be measured, a peak hold means for detecting and holding a peak value of an electromotive force generated between the electrodes in the sensor, and the peak An ozone water concentration measuring apparatus comprising: concentration display means for displaying a dissolved ozone concentration corresponding to the voltage value held by the holding means.   The ozone water concentration according to claim 1, wherein a resistor for adjusting linearity of the electromotive force with respect to a dissolved ozone concentration of a liquid to be measured is connected between a pair of electrodes constituting the sensor. measuring device.   The concentration of ozone water according to claim 1 or 2, wherein gold (Au) is used as one electrode material constituting the sensor and silver silver chloride (Ag / AgCl) is used as the other electrode material. measuring device.

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