JP6665751B2 - Water quality analyzer - Google Patents

Description

  The present invention relates to a water quality analyzer, and more particularly to a total nitrogen measuring device for measuring a total nitrogen concentration in a sample liquid.

The method for measuring total nitrogen, which represents the total amount of total nitrogen compounds in the sample liquid of factory effluents by the concentration of nitrogen, is based on the "UV absorption spectrophotometric method specified in the Japanese Industrial Standards" Testing methods for wastewater discharged from factories ". (JIS K 0102 45.2) is generally used. This ultraviolet absorption spectrophotometry is a method in which a sample solution to which potassium peroxodisulfate, which is an oxidizing agent, is added is subjected to an autoclave method, that is, a method in which the sample solution is treated under high temperature and high pressure.
Further, a total nitrogen measuring apparatus employing a method combining “ultraviolet oxidative decomposition” with “ultraviolet absorption spectrophotometry” (hereinafter referred to as “ultraviolet oxidative decomposition”) is also commercially available.

In the ultraviolet oxidation decomposition method, a predetermined amount a of the sample liquid S collected is first measured and diluted with a predetermined amount b of dilution water. Then, a predetermined amount c of sodium hydroxide solution (NaOH) is added as a pretreatment for making the sample solution S alkaline so that the nitrogen compounds in the sample solution S are easily decomposed. Then, potassium peroxodisulfate solution of a predetermined amount d of the oxidizing agent is added, adjusting the sample solution S ₁ of a predetermined amount (a + b + c + d ) is transferred to the ultraviolet oxidation decomposition step.

Then, the adjustment sample solution S ₁ ultraviolet rays are irradiated under heating above 70 ° C., the nitrogen compound of the adjustment sample liquid S in ₁ and the reaction sample liquid S ₂ is oxidized decomposed into nitrate ions in response to ultraviolet Become. Thereafter, was added hydrochloric acid or the like of a predetermined amount e to adjust the pH during the absorbance measurement, a predetermined amount (a + b + c + d + e) measurement of the total nitrogen concentration in the adjusted sample liquid S ₃ of is performed by absorbance measurements in the vicinity of 220 nm (e.g. Patent Document 1).

FIG. 4 is a diagram schematically showing an example of the overall configuration of a conventional on-line total nitrogen measuring device. FIG. 2 is a cross-sectional view illustrating an example of the configuration of the measurement unit. One direction parallel to the ground is defined as an X direction, a direction parallel to the ground and perpendicular to the X direction is defined as a Y direction, and a direction perpendicular to the X direction and the Y direction is defined as a Z direction.
The online total nitrogen measuring apparatus 101 includes a sample tank 2, a syringe pump (a measuring unit) 12, a first multiport valve 20, a second multiport valve 30, a reactor 40, a measuring unit 50, a container 3 to A computer 160 is provided with the arranging unit 70 in which 11 is arranged.

  The sample tank 2 is configured to be continuously supplied with a sample liquid S such as factory wastewater or environmental water, and is connected to one distribution port of the first multiport valve 20.

  The syringe pump 12 includes a cylindrical syringe 12a, a cylindrical piston 12b inserted into the syringe 12a, and a pulse motor 12c controlled by a computer 160. The piston 12b of the syringe pump 12 moves up and down by a pulse motor 12c. When the piston 12b is pulled downward, a predetermined amount of solution is injected into the syringe 12a, and the piston 12b is pushed upward. And a predetermined amount of solution in the syringe 12a.

  The first multi-port valve 20 includes eight distribution ports and one common port. The distribution tank is connected to the sample tank 2, the container 3 containing the span liquid, the container 4 containing the standard sample liquid, the container 5 containing the dilution water, the reactor 40, and the measuring unit 50. The first multi-port valve 20 is driven by a motor (not shown), and selectively connects the common port and one distribution port.

  The second multiport valve 30 includes eight distribution ports and one common port. In the distribution port, a container 6 containing a potassium peroxodisulfate solution, a container 7 containing a sodium hydroxide solution, a container 8 containing hydrochloric acid, a container 9 containing molybdic acid, a container 10 containing ascorbic acid, a container 11 containing sulfuric acid, The common port of the first multi-port valve 20 is connected. Further, the common pump of the second multiport valve 30 is connected to the syringe pump 12. The second multiport valve 30 is driven by a motor (not shown), and selectively connects the common port and one distribution port.

The reactor 40 includes a reaction vessel 41 for accommodating the adjustment sample solution S _1, the ultraviolet lamp 42 for irradiating ultraviolet rays to adjust the sample solution S _1, a heater for controlling the oxidation reaction temperature of the conditioned sample solution S ₁ (shown ).
The reaction vessel 41 has a cylindrical (for example, an outer diameter of 12 mm, an inner diameter of 10 mm, and a height of 130 mm) side wall and a circular lower surface, and a sample liquid inlet connected to the first multiport valve 20 is provided below the side wall. A sample liquid outlet is formed on the lower surface and connected to a drain for treating waste liquid. The reaction vessel 41 is formed of quartz glass or the like.

  As shown in FIG. 2, the measuring unit 50 detects a semiconductor laser element (light source unit) 51 that emits a laser beam having a wavelength of 220 nm to the right (X direction) and detects the light intensity of the laser beam traveling in the X direction. It includes a photodiode (detection unit) 52 and a measurement cell (sample container) 53 arranged between the semiconductor laser element 51 and the photodiode 52. The light source unit is not limited to a semiconductor laser element, but may be a xenon flash lamp or the like.

The measurement cell 53 includes a cylindrical (for example, an outer diameter of 12 mm, an inner diameter of 10 mm, and a height of 130 mm) side wall 53a and a circular lower surface 53b, and the lower surface 53b is connected to a distribution port of the first multiport valve 20. A sample liquid inlet 53c is formed. Note that the measurement cell 53 is formed of quartz glass or the like.
As a result, the laser light emitted from the semiconductor laser element 51 passes through the side wall 53a, passes through the measurement target area (optical path), and is received by the photodiode 52 after passing through the opposite side wall 53a. I have. At this time, the adjustment sample liquid S _3, if present in the measurement target region, part of the laser light is absorbed by adjusting the sample solution S _3.

Here, a method for automatically analyzing the total nitrogen concentration of the sample liquid S using the above-described online total nitrogen measuring device 101 will be described. First, the user places the containers 3 to 11 containing the reagents on the placement unit 70. The computer 160 outputs a drive signal to the pulse motor 12c at a predetermined timing, thereby measuring and collecting a predetermined amount a of the sample liquid S from the sample tank 2 with the syringe pump 12, and driving the pulse motor 12c again. By outputting a signal, a predetermined amount b of dilution water is measured and collected by the syringe pump 12 from the container 5, and the sample liquid S is diluted in the syringe 12a. Next, the computer 160 outputs a drive signal to the pulse motor 12c to add a predetermined amount c of sodium hydroxide solution in the container 7 and a predetermined amount d of potassium peroxodisulfate solution in the container 6 into the syringe 12a. after the adjustment sample solution S ₁ was, by outputting a drive signal to the pulse motor 12c again, a predetermined amount of adjustment sample solution S ₁ of (a + b + c + d ) is introduced from the syringe pump 12 to the reactor 40.

In the reactor 40, for about 20 minutes ultraviolet irradiation to adjust the sample solution S ₁ by an ultraviolet lamp 42, the nitrogen compound with oxidation decomposition nitrate ions, decomposes potassium peroxodisulfate in the solution of potassium sulfate. After all potassium peroxodisulfate is decomposed, ultraviolet rays are further irradiated for 5 to 20 minutes to reduce nitrate ions to nitrite ions. After these reaction has ended, the computer 160, by outputting a drive signal to the pulse motor 12c, a predetermined amount of the reaction sample liquid S ₂ of (a + b + c + d ) were collected and weighed with a syringe pump 12, again a pulse motor 12c by outputting a drive signal to, to generate an adjusted sample liquid S ₃ of a predetermined amount by adding hydrochloric acid of a predetermined amount e of the container 8 in the syringe 12a (a + b + c + d + e).

Next, the computer 160, by outputting a drive signal to the pulse motor 12c, after the introduction predetermined amount (a + b + c + d + e) adjusting the sample solution _{S 3} to the measurement cell 53 from the syringe pump 12, the laser beam from the semiconductor laser element 51 The light is emitted, and the light intensity is detected by the photodiode 52. Then, the computer 160, by measuring the absorbance I at 220nm on the basis of the detected light intensity, and calculates the total nitrogen concentration in the adjusted sample liquid S _3.

JP-A-2003-344381

By the way, some of the reagents (potassium peroxodisulfate solution, ascorbic acid, etc.) used in the measurement are deteriorated with time to change the concentration X. In many cases, the degree of the concentration change depends on the surrounding environment in which the reagent is placed, and it is difficult to accurately predict the concentration change.
In the above-described line total nitrogen measurement device 101, since the concentration X of the reagents required for proper chemistry adjustment sample solution S ₁ containing the sample liquid S and dilution water and potassium peroxodisulfate solution or the like is fixed, When the concentration changes, a correct measurement value (absorbance I) cannot be measured. Therefore, from the viewpoints of maintainability and cost, it is better that the replacement cycle of the reagents in the containers 3 to 11 is slow, so that the concentration change due to deterioration does not affect the measured value (absorbance I) in advance, and the period from the start of use ( (A span of several days to several months) is set, and the user replenishes or replaces the reagent in the placement unit 70 within this reagent expiration date.

  However, the problem of increasing the time and labor required for reagent preparation and replacement, and in fact, even when the surrounding environment is favorable and the degree of concentration change is low and the reagent is usable, the reagent should be discarded when the reagent expiration date is reached. There was a problem that there was waste.

In the measuring unit 50 having the measuring cell 53 and the photodiode 52, the applicant of the present invention has a method of measuring the total nitrogen concentration of the sample liquid S, and adding one reagent (potassium peroxodisulfate) to the measuring cell 53 instead of the sample liquid S. It was noted that the reagent concentration X can be determined by introducing only a solution or ascorbic acid). That is, to quantify the reagent concentration X regularly concentration change is expected, by changing the amount of collected reagent according to quantitative reagent concentration X (the predetermined amount d and the like), the adjustment sample liquid S in ₁ It has been found that a correct measurement value (absorbance I) can be obtained by keeping the concentration of potassium peroxodisulfate X constant.

As a specific method for quantitating reagent concentration X, when the reagent usage start, in a state with known reagent concentration X _0, after introducing a reagent into the measurement cell, the light of a certain measurement wavelength in the measuring cell irradiated, record the obtained absorbance I in a computer, and this is referred to as reference absorbance I ₀ (see FIG. 3). The absorbance I is the optical path length of the measuring cell is constant, is proportional to the concentration X, current reagent concentration X can be calculated by using the absorbance I and the reference absorbance I ₀ obtained in the measurement of periodic reagents .
As a result, even if there is a change in the reagent concentration X that affects the measured value (absorbance I) of the sample solution S, it can be compensated for by the amount of the collected reagent. It is possible to use up to the end.

That is, the water quality analyzer of the present invention comprises a measurement cell, a light source unit that irradiates the measurement cell with light, a detection unit that detects light transmitted through the measurement cell, a sample solution and a predetermined amount of a reagent. A measuring unit for introducing the sample solution and a predetermined amount of reagent into the measurement cell, and measuring the absorbance based on the light detected by the detection unit, and measuring the concentration of the target component in the sample solution based on the absorbance. a water quality analyzer and a control unit which calculates, the control unit, the reagent was allowed to metered to introducing the reagent into the measurement cell, based on the detected light by the detecting unit to the weighing unit Measure the absorbance of the reagent , calculate the concentration of the predetermined component in the reagent using the absorbance of the reagent and the reference absorbance measured in advance for the reagent having the predetermined concentration, based on the calculated concentration of the predetermined component And the measuring section It is as in determining the predetermined amount of reagent.

Here, the “predetermined amount” is an arbitrary amount determined by a user or the like to cause the target component in the sample solution to react.
Et al is, the "predetermined component" is any component for measuring the concentration of the reagents is determined by the user or the like.

  As described above, according to the water quality analyzer of the present invention, maintenance work and cost reduction can be achieved. In addition, by applying the detection unit and the like used for measuring the concentration of the target component in the sample liquid to the measurement of the concentration of the reagent, it can be realized without adding new hardware.

In the above invention, the control unit stores the calculated predetermined component concentration X in the reagent in the memory, and when analyzing the sample liquid, the predetermined concentration X0 and the predetermined component concentration X And the predetermined amount d ′ of the reagent to be measured by the measuring section may be determined based on the following equation (1).
d ′ = d × X0 / X (1)

Further, in the water quality analyzer of the present invention, an arrangement unit for disposing the reagent may be provided, and the control unit may determine whether to replace the reagent.
According to the water quality analyzer of the present invention, it is necessary to change the reagent before the reagent concentration changes too much and the collection amount of the reagent reaches the limit (upper limit). By applying the history information obtained in the above, the control unit predicts the replacement time of the reagent, and by incorporating a mechanism for notifying the user of it, it is possible to notify the user of the appropriate replacement time of the reagent. it can.

  And in the water quality analyzer of the present invention, the reagent may be a solution containing an oxidizing agent.

Furthermore, in the water quality analyzer of the present invention, the light source unit may be configured to be able to switch a wavelength of emitted light.
ADVANTAGE OF THE INVENTION According to the water quality analyzer of this invention, the trouble of maintenance and reduction of cost about various types of reagents are attained.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram of the whole structure which shows the total nitrogen measuring apparatus which is an example of this invention. Sectional drawing which shows an example of a structure of a measurement part. 5 is a graph showing an example of a change in absorbance. FIG. 1 is a schematic diagram of the entire configuration showing an example of a conventional total nitrogen measuring device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and it goes without saying that various aspects are included without departing from the gist of the present invention.

FIG. 1 shows a schematic overall configuration example of an on-line total nitrogen measuring device as an example of a water quality analyzer according to the present invention. In addition, about the thing similar to the above-mentioned on-line total nitrogen measuring apparatus 101, description is abbreviate | omitted by attaching | subjecting the same code | symbol.
The online total nitrogen measuring apparatus 1 includes a sample tank 2, a syringe pump (a measuring unit) 12, a first multiport valve 20, a second multiport valve 30, a reactor 40, a measuring unit 50, a container 3 to A computer 60 is provided with an arranging unit 70 in which 11 is arranged.

The computer 60 includes a CPU (control unit) 61, a display device 62 such as a monitor, and a memory 63. The function performed by the CPU 61 will be described in the form of a block. The acquisition unit 61a acquires the light intensity from the photodiode (detection unit) 52, and the absorbance measures the absorbance I of the sample liquid S based on the detected light intensity. It has a calculation unit 61b and a determination unit 61c that measures the absorbance I of the reagent based on the detected light intensity. Further, the memory 63, together with the reference absorbance I ₀ for calculating the reagent concentration X is stored, the threshold value ΔI for determining the replacement time are stored in advance.

The determination unit 61c performs control to measure the absorbance I of the reagent based on the light intensity detected by the photodiode 52 when the reagent is contained in the measurement cell 53. FIG. 3 is a graph showing an example of a change in absorbance.
For example, when the user places the potassium peroxodisulfate solution container containing 6 concentrations X ₀ to the arrangement section 70, the determination unit 61c, by outputting a drive signal to the pulse motor 12c, a predetermined amount D of the container 6 The potassium peroxodisulfate solution is measured and collected by the syringe pump 12. Next, the determination unit 61c introduces a predetermined amount D of the potassium peroxodisulfate solution from the syringe pump 12 into the measurement cell 53 by outputting a drive signal to the pulse motor 12c. Then, the determination unit 61c emits laser light from the semiconductor laser element (light source unit) 51 and causes the photodiode 52 to detect light intensity. Next, the determination unit 61c causes the memory 63 to store the reference absorbance I ₀ and the concentration X ₀ by measuring the absorbance I at 220 nm based on the detected light intensity.

Thereafter, at a predetermined timing (for example, once a day, every 10 measurements, or the like) , the determination unit 61c outputs a drive signal to the pulse motor 12c so that the predetermined amount D of the peroxodisulfate in the container 6 is output. The potassium solution is measured by the syringe pump 12 and collected. Next, the determination unit 61c introduces a predetermined amount D of the potassium peroxodisulfate solution from the syringe pump 12 into the measurement cell 53 by outputting a drive signal to the pulse motor 12c. Then, the determination unit 61c causes the semiconductor laser element 51 to emit laser light, and causes the photodiode 52 to detect the light intensity. Next, the determination unit 61c measures the absorbance I at 220 nm based on the detected light intensity. Next, the determination unit 61 c calculates the current concentration X of the potassium peroxodisulfate solution using the reference absorbance I ₀ and the absorbance I stored in the memory 63 and stores the calculated concentration X in the memory 63. At this time, when the difference between the reference absorbance I ₀ and the absorbance I is equal to or more than the threshold value ΔI, it is determined that the potassium peroxodisulfate solution is excessively deteriorated (for example, when d ′> (b + d)) and displayed. The display is performed on the device 62.

Absorbance calculation section 61b, the concentration X, which is stored in the memory 63, _{X 0} and the following formula (1) (2) and together produce the adjusted sample liquid _{S 1} based on the adjusted sample liquid _{S 3} in the measurement cell 53 Is controlled based on the light intensity detected by the photodiode 52 when is stored.
For example, the absorbance calculation unit 61b outputs a drive signal to the pulse motor 12c at a predetermined timing, thereby measuring and collecting a predetermined amount a of the sample liquid S from the sample tank 2 with the syringe pump 12, and re-sampling the pulse motor 12c. , A predetermined amount b 'of dilution water is measured and collected from the container 5 by the syringe pump 12, and the sample liquid S is diluted in the syringe 12a. Next, the absorbance calculation unit 61b outputs a drive signal to the pulse motor 12c, so that a predetermined amount c of sodium hydroxide solution in the container 7 and a predetermined amount d ′ of potassium peroxodisulfate solution in the container 6 are output into the syringe 12a. after preparative an adjustment sample solution S ₁ was added, by outputting a drive signal to the pulse motor 12c again introducing a predetermined amount of adjustment sample solution S ₁ of (a + b '+ c + d') from the syringe pump 12 to the reactor 40 I do.
d ′ = d × X ₀ / X (1)
b ′ = b− (d′−d) (2)

In the reactor 40, for about 20 minutes ultraviolet irradiation to adjust the sample solution S ₁ by an ultraviolet lamp 42, as well as oxidative degradation of nitrogen compounds to nitrate ions, decomposes potassium peroxodisulfate in the solution of potassium sulfate. After all potassium peroxodisulfate is decomposed, ultraviolet rays are further irradiated for 5 to 20 minutes to reduce nitrate ions to nitrite ions. After these reaction has ended, the absorbance calculation section 61b by outputting a drive signal to the pulse motor 12c, a predetermined amount (a + b '+ c + d') reaction sample solution S ₂ was collected and weighed with a syringe pump 12 by outputting a drive signal to the pulse motor 12c again, a predetermined amount of hydrochloric acid was added to the predetermined amount e of the container 8 in the syringe 12a (a + b '+ c + d' + e) to generate the adjusted sample liquid S ₃ of.

Next, the absorbance calculation section 61b by outputting a drive signal to the pulse motor 12c, after introduction into a predetermined amount (a + b '+ c + d' + e) adjusting the sample solution _{S 3} measuring cell 53 from the syringe pump 12, a semiconductor laser The laser light is emitted from the element 51 and the light intensity is detected by the photodiode 52. The absorbance calculation section 61b, by measuring the absorbance I at 220nm on the basis of the detected light intensity, and calculates the total nitrogen concentration in the adjusted sample liquid S _3.

  As described above, according to the online total nitrogen measurement apparatus 1 having the configuration according to the present invention, it is possible to reduce the labor and cost of maintenance. In addition, by applying the measuring unit 50 used for measuring the nitrogen concentration in the sample liquid S to the measurement of the reagent concentration, it can be realized without adding new hardware.

<Other embodiments>
<1> In the online total nitrogen measuring apparatus 1 described above, a configuration in which only the concentration X of the potassium peroxodisulfate solution is calculated has been described, but the present invention may be applied to other reagents. At this time, a configuration in which a light source unit capable of switching the wavelength of the emitted light may be provided.

<2> In the above-described embodiment, the configuration in the case where the present invention is applied to the online total nitrogen measurement device 1 has been described. However, the present invention may be applied to other water quality analyzers instead.

  INDUSTRIAL APPLICABILITY The present invention can be used for a water quality analyzer such as a total nitrogen measuring device for measuring the total nitrogen concentration in a sample liquid.

1: Online total nitrogen analyzer (water quality analyzer)
12: Syringe pump (measuring unit)
51: Semiconductor laser device (light source unit)
52: Photodiode (detection unit)
53: Measurement cell 61: CPU (control unit)

Claims (5)

A measuring cell,
A light source unit for irradiating the measurement cell with light,
A detection unit that detects light transmitted through the measurement cell,
A measuring unit for measuring a sample liquid and a predetermined amount of reagent and introducing the sample liquid and a predetermined amount of reagent into the measurement cell;
A water quality analyzer comprising: a controller that measures absorbance based on light detected by the detection unit and calculates a target component concentration in the sample liquid based on the absorbance .
The control unit includes:
The measuring section measures the reagent, introduces the reagent into the measurement cell, measures the absorbance of the reagent based on the light detected by the detection section, and has the absorbance of the reagent and a predetermined concentration. Calculating the concentration of a predetermined component in the reagent using the reference absorbance measured in advance for the reagent ,
A water quality analyzer, wherein a predetermined amount of a reagent to be measured by the measuring section is determined based on the calculated concentration of the predetermined component. The control unit stores the calculated predetermined component concentration X in the reagent in the memory, and when analyzing the sample liquid, the predetermined concentration X0, the predetermined component concentration X, and the following equation: The water quality analyzer according to claim 1, wherein a predetermined amount d 'of the reagent to be measured by the measuring unit is determined based on (1).
d ′ = d × X0 / X (1) An arrangement unit for arranging the reagent,
The water quality analyzer according to claim 1, wherein the control unit determines whether to replace the reagent.   4. The water quality analyzer according to claim 1, wherein the reagent is a solution containing an oxidizing agent. The water quality analyzer according to any one of claims 1 to 4, wherein the light source unit is capable of switching a wavelength of emitted light.

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