JP6965502B2 - 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 the total nitrogen concentration in a sample solution.

The method for measuring total nitrogen, which expresses the total amount of total nitrogen compounds in a sample solution such as factory wastewater by the concentration of nitrogen, is the "ultraviolet absorptiometry" specified in the "Test method for wastewater discharged from factories" of the Japanese Industrial Standards. "(JIS K 0102 45.2) is commonly used. This ultraviolet absorptiometry is an autoclave method, that is, a method of treating a sample solution to which potassium persulfate, which is an oxidizing agent, is added, under high temperature and high pressure.
In addition, a total nitrogen measuring device that employs a method that combines "ultraviolet absorptiometry" with "ultraviolet oxidative decomposition" (hereinafter referred to as "ultraviolet oxidative decomposition method") is also commercially available.

In the ultraviolet oxidative decomposition method, the sample liquid S of the predetermined amount a collected is first weighed and diluted with the diluted water of the predetermined amount b. Then, a predetermined amount of sodium hydroxide solution (NaOH) is added as a pretreatment for making the sample liquid S alkaline so that the nitrogen compound in the sample liquid S is easily decomposed. Next, after a predetermined amount d of potassium persulfate solution serving as an oxidizing agent is added, a predetermined amount (a + b + c + d) of the prepared sample solution S1 is transferred to the ultraviolet oxidative decomposition step.

Then, the adjusted sample solution S1 is irradiated with ultraviolet rays under heating conditions of 70 ° C. or higher, and the nitrogen compound in the adjusted sample solution S1 is oxidatively decomposed into nitrate ions in response to the ultraviolet rays to become the reaction sample solution S2. After that, a predetermined amount of hydrochloric acid or the like for adjusting the pH is added at the time of absorbance measurement, and the total nitrogen concentration in the adjusted sample solution S3 of a predetermined amount (a + b + c + d + e) is measured by measuring the absorbance at around 220 nm (for example, patent). Reference 1).

FIG. 4 is a diagram schematically showing an example of the overall configuration of a conventional online total nitrogen measuring device. Further, an example of the configuration of the reactor and the measuring unit is shown in cross-sectional views in FIGS. One direction horizontal to the ground is the X direction, the direction horizontal to the ground and perpendicular to the X direction is the Y direction, and the direction perpendicular to the X direction and the Y direction is the Z direction.
The online total nitrogen measuring device 101 includes a sample tank 2, a syringe pump (measuring unit) 12, a first multiport valve 20, a second multiport valve 30, a reactor 40, a measuring unit 50, and a computer 160. To be equipped.

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 multi-port 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. Then, the piston 12b of the syringe pump 12 is moved up and down by the pulse motor 12c, and 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 is discharged.

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

The second multi-port valve 30 includes eight distribution ports and one common port. The distribution port includes 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, and a container 11 containing sulfuric acid. The common port of the first multi-port valve 20 is connected. Further, a syringe pump 12 is connected to the common port of the second multi-port valve 30. The second multi-port valve 30 is driven by a motor (not shown) to selectively connect the common port and one distribution port.

As shown in FIG. 2, the reactor 40 controls the reaction vessel 41 for accommodating the adjusted sample solution S1, the ultraviolet lamp 42 for irradiating the adjusted sample solution S1 with ultraviolet rays, and the oxidation reaction temperature of the adjusted sample solution S1. A heater 43 is provided.

The reaction vessel 41 is composed of a cylindrical (for example, outer diameter 12 mm, inner diameter 10 mm, height 130 mm) side wall 41a and a circular lower surface 41b, and a sample connected to the first multiport valve 20 under the side wall 41a. A liquid introduction port 41c is formed, and a sample liquid discharge port 41d connected to a drain for treating waste liquid is formed on the lower surface 41b. The reaction vessel 41 is made of quartz glass or the like.
The heater 43 includes a metal cylindrical block body and a thermocouple (not shown) embedded in the block body, and is arranged so as to come into contact with the outer peripheral surface of the reaction vessel 41.

The ultraviolet lamp 42 is, for example, a low-pressure mercury lamp, an excimer laser, a deuterium lamp, a xenon lamp, an Hg-Zn-Pb lamp, or the like.
The ultraviolet lamp 42 is inserted into the central portion of the reaction vessel 41 from above and arranged. As a result, when a predetermined amount of the adjusted sample solution S1 is contained in the reaction vessel 41, the ultraviolet lamp 42 is immersed in the adjusted sample solution S1.

As shown in FIG. 3, the measuring unit 50 includes a semiconductor laser element (light source unit) 51 that emits laser light to the right (X direction) and a photodiode that detects the light intensity I of the laser light traveling in the X direction. A (detection unit) 52 and a measurement cell (sample container) 53 arranged between the semiconductor laser element 51 and the photodiode 52 and accommodating a predetermined amount of the adjusted sample liquid S3 are provided. The light source unit is not limited to the semiconductor laser element, and may be a xenon flash lamp or the like.

The measurement cell 53 is composed of a cylindrical (for example, outer diameter 12 mm, inner diameter 10 mm, height 130 mm) side wall 53a and a circular upper surface 53b and lower surface 53c, and the upper surface 53b is connected to a drain for treating waste liquid. A sample liquid discharge port 53d is formed, and a sample liquid introduction port 53e connected to the first multi-port valve 20 is formed on the lower surface 53c. The measurement cell 53 is made 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 region (optical path), passes through the side wall 53a on the opposite side, and is received by the photodiode 52. There is. At this time, if the adjusted sample solution S3 is present in the measurement target region, a part of the laser beam is absorbed by the adjusted sample solution S3.

Here, a method for automatically analyzing the total nitrogen concentration of the sample liquid S using the above-mentioned online total nitrogen measuring device 101 will be described. By outputting a drive signal to the pulse motor 12c at a predetermined timing, the computer 160 measures and collects a predetermined amount of the sample liquid S from the sample tank 2 with the syringe pump 12, and again outputs the drive signal to the pulse motor 12c. By outputting, a predetermined amount of diluted water b is weighed and collected from the container 5 by the syringe pump 12, and the sample liquid S is diluted in the syringe 12a. Next, the computer 160 adds a predetermined amount c of the sodium hydroxide solution of the container 7 and a predetermined amount d of the potassium peroxodisulfate solution of the container 6 into the syringe 12a by outputting a drive signal to the pulse motor 12c. Then, after the adjustment sample solution S1 is obtained, a predetermined amount (a + b + c + d) of the adjustment sample solution S1 is introduced into the reactor 40 from the syringe pump 12 by outputting a drive signal to the pulse motor 12c again.

In the reactor 40, the adjusted sample solution S1 is irradiated with ultraviolet rays by an ultraviolet lamp 42 for about 20 minutes to oxidatively decompose the nitrogen compound into nitrate ions and decompose potassium peroxodisulfate in the solution into potassium sulfate. Then, after decomposing all potassium persulfate, nitrate ions are reduced to nitrite ions by further irradiating with ultraviolet rays for 5 to 20 minutes. After these reactions are completed, the computer 160 outputs a drive signal to the pulse motor 12c to measure and collect a predetermined amount (a + b + c + d) of the reaction sample solution S2 with the syringe pump 12 and again to the pulse motor 12c. By outputting the drive signal, a predetermined amount of hydrochloric acid of the container 8 is added in the syringe 12a to generate a predetermined amount (a + b + c + d + e) of the adjusted sample solution S3.

Next, the computer 160 outputs a drive signal to the pulse motor 12c to introduce a predetermined amount (a + b + c + d + e) of the adjustment sample solution S3 from the syringe pump 12 into the measurement cell 53, and then emits laser light from the semiconductor laser element 51. Then, the light intensity I is detected by the photodiode 52. Then, the computer 160 calculates the total nitrogen concentration of the prepared sample solution S3 by measuring the absorbance at 220 nm based on the detected light intensity I.

Japanese Unexamined Patent Publication No. 2003-344381

In the online total nitrogen measuring device 101 as described above, the required amount of liquid is supplied to the syringe pump 12 due to insufficient liquid volume in the sample tank 2 or containers 3 to 11 or an abnormality in the piping or the like. The adjusted sample solution S3 has a predetermined amount (a + b + c + d + e) due to leakage of the adjusted sample solution S3 in the process of collecting the sample solution with the syringe pump 12 and sending the solution to the measurement cell 53. In some cases, the liquid was not sent into the measurement cell 53.
However, since the online total nitrogen measuring device 101 automatically calculates the total nitrogen concentration of the sample liquid S, the analyst or the like may not be able to detect an abnormal state such as liquid shortage or liquid leakage, or the detection may be delayed. As a result, the total nitrogen concentration of the sample solution S may not be accurately measured.

The applicant examines a detection method for detecting an abnormal state of the online total nitrogen measuring device 101, and detects whether or not a predetermined amount (a + b + c + d + e) of the adjusted sample liquid S3 has been sent into the measuring cell 53. I paid attention to it. As a method for detecting such a water sampling abnormality, the presence or absence of the adjusted sample solution S3 is obtained by sending the adjusted sample solution S3 into the measurement cell 53 and then checking the magnitude of the light transmittance detected by the photodiode 52. Can be detected.
However, in the conventional online total nitrogen measuring device 101, when the amount of any one of the sample tank 2 and the containers 3 to 11 is insufficient, the inside of the measuring cell 53 becomes empty (none). There is no such thing. For example, even if a predetermined amount of the potassium persulfate solution d is not added and the prepared sample solution S3'of (a + b + c + e) is sent into the measurement cell 53, it is determined that there is no problem. Therefore, a detection method for determining whether or not the inside of the measurement cell 53 is empty (none) is insufficient.

By the way, when the adjusted sample solution S3 is sent into the measurement cell 53 as described above, (1) the interface of the adjusted sample solution S3 layer has not reached the optical path (measurement target region), and (2) the optical path. The state in which the interface of the adjusted sample solution S3 layer has reached the inside and the state in which (3) the optical path is in the adjusted sample solution S3 layer are sequentially changed. At this time, when the adjustment sample liquid S3 is sent into the measurement cell 53 while the semiconductor laser element 51 is lit, the measurement cell 53 is changed from an empty state to a state in which a predetermined amount (a + b + c + d + e) of the adjustment sample liquid S3 is contained. The light intensity change I (L) obtained in the process of becoming the above has a characteristic waveform with respect to the liquid feed amount L of the adjusted sample liquid S3. As shown in FIG. 5, this waveform starts from "(1) a state in which the increase / decrease in light intensity I is relatively small" with respect to the liquid feed amount L, and "(2) the increase / decrease in light intensity I is relatively large". After passing through the "state", finally, the "(3) state in which the increase / decrease in the light intensity I is relatively small" is obtained again.

Normally, the amount of liquid to be fed when the adjusted sample liquid S3 is fed into the measurement cell 53 is uniquely determined by the type of measurement, so that the type of measurement (for example, the amount of liquid to be fed (a + b + c + d + e)) is determined. Then, in the obtained light intensity change I (L), the liquid feeding amount point L'that becomes "(2) a state in which the increase / decrease in the light intensity I is relatively large" is also determined. Therefore, in the obtained light intensity change I (L), when "(2) a state in which the increase / decrease in light intensity I is relatively large" is larger than the liquid feeding amount point L', or "(1) increase / decrease in light intensity I". If "(2) The increase / decrease in light intensity I is relatively large" does not occur while "is relatively small", the amount of liquid sent into the measurement cell 53 is insufficient. That is, there is a water sampling abnormality in the process from the measurement by the syringe pump 12 to the delivery of the liquid to the measurement cell 53.

Therefore, the adjusted sample liquid S3 is sent into the measurement cell 53 while the semiconductor laser element 51 is lit, and the light intensity I at that time is monitored, and at the point where a relatively large fluctuation of the light intensity I occurs. It has been found that when the liquid feed amount L is larger than the reference liquid feed amount L', or when the light intensity I does not fluctuate, it is determined that the water sampling is abnormal.

That is, in the water quality analyzer of the present invention, a sample container in which a sample solution introduction port is formed at the lower part and the sample solution is introduced from the sample solution introduction port, a light source unit that irradiates the sample container with light, and the sample. A detection unit that detects the light transmitted through the container, and a memory that stores a change in light intensity with respect to the reference liquid feed amount detected by the detection unit when a predetermined amount of sample liquid is introduced into the sample container. A water quality analyzer comprising the above, in which a change in light intensity with respect to an actually measured liquid feed amount detected by the detection unit when the sample liquid is contained in the sample container and a change in light intensity for reference are obtained. For comparison, a determination unit for determining whether or not the predetermined amount of the sample solution is contained in the sample container is provided.

Here, the "predetermined amount" is an arbitrary amount for measuring the absorbance of the sample solution or the like, which is predetermined by an analyst or the like.

As described above, according to the water quality analyzer of the present invention, it is possible to quickly detect an abnormal state due to liquid shortage or liquid leakage.

(Means and effects to solve other problems)
Further, in the water quality analyzer of the present invention, the sample container may be a measurement cell for analyzing the sample solution or a reaction container for reacting the sample solution.
Further, the water quality analyzer of the present invention includes a measuring unit for measuring the sample liquid, a valve connected to the sample liquid introduction port and the measuring unit, and a control unit for controlling the measuring unit and the valve. You may be prepared.

The overall configuration schematic diagram which shows the total nitrogen measuring apparatus which is an example of this invention. FIG. 5 is a cross-sectional view showing an example of the configuration of the reactor. The cross-sectional view which shows an example of the structure of the measuring part. The overall configuration schematic diagram which shows an example of the conventional total nitrogen measuring apparatus. The graph which shows an example of the light intensity change.

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

As an example of the water quality analyzer according to the present invention, FIG. 1 shows a schematic overall configuration example of the online total nitrogen measuring device. The same reference numerals as those of the above-mentioned online total nitrogen measuring apparatus 101 will be described by the same reference numerals.
The online total nitrogen measuring device 1 includes a sample tank 2, a syringe pump (measuring unit) 12, a first multiport valve 20, a second multiport valve 30, a reactor 40, a measuring unit 50, and a computer 60. To be equipped.

The computer 60 includes a CPU (control unit) 61, a display device 62 such as a monitor, and a memory 63. Further, to explain the function processed by the CPU 61 in a blocked manner, the acquisition unit 61a that acquires the light intensity I from the photodiode (detection unit) 52 and the absorbance calculation unit 61b that calculates the absorbance based on the detected light intensity I It has a determination unit 61c for determining whether or not a predetermined amount of the adjusted sample solution S3 is contained based on the light intensity change I (L), and a measurement unit control unit 61d for controlling the syringe pump 12.

Further, in order to determine the water sampling abnormality, the memory 63 has a reference liquid feeding amount in which "(2) a state in which the increase / decrease in light intensity I is relatively large" when the adjusted sample liquid S3 is fed in a predetermined amount (a + b + c + d + e). L'(for example, 900 μl) is stored in advance.

The determination unit 61c has a predetermined amount (a + b + c + d + e) in the measurement cell 53 based on the light intensity change I (L) detected by the photodiode 52 when the adjustment sample liquid S3 is housed in the measurement cell 53. Control is performed to determine whether or not the prepared sample liquid S3 is contained.
Specifically, the amount of inclination of the curve of the light intensity change I (L) detected by the photodiode 52 when the reaction sample liquid S2 is accommodated in the measurement cell 53 is sequentially examined, and the amount of inclination is a predetermined value. When it becomes less than or equal to, it is determined to be the start point of the peak, when the inclination amount changes from negative to positive, it is determined to be the peak (liquid feeding amount point L), and further, the inclination amount is equal to or less than a predetermined value. When becomes, it is determined that the end point of the peak is reached. Then, when the liquid feeding amount point L is larger than the reference liquid feeding amount L', it is determined that the liquid feeding amount into the measurement cell 53 is insufficient, and a warning is displayed on the display device 62. Further, even when the peak is not detected, it is determined that the amount of liquid sent into the measurement cell 53 is insufficient, and a warning is displayed on the display device 62.

Here, a method for automatically analyzing the total nitrogen concentration of the sample solution S using the online total nitrogen measuring device 1 described above will be described. The measuring unit control unit 61d of the computer 60 outputs a drive signal to the pulse motor 12c at a predetermined timing to measure and collect a predetermined amount of the sample liquid S from the sample tank 2 with the syringe pump 12, and then pulse again. By outputting a drive signal to the motor 12c, a predetermined amount of diluted water b is weighed and collected from the container 5 by the syringe pump 12, and the sample liquid S is diluted in the syringe 12a. Next, the measuring unit control unit 61d outputs a drive signal to the pulse motor 12c, so that a predetermined amount c of the sodium hydroxide solution of the container 7 and a predetermined amount d of the potassium peroxodisulfate solution of the container 6 are contained in the syringe 12a. Is added to prepare the adjusted sample solution S1, and then a drive signal is output to the pulse motor 12c again to introduce a predetermined amount (a + b + c + d) of the adjusted sample solution S1 from the syringe pump 12 into the reactor 40.

In the reactor 40, ultraviolet rays are irradiated to the adjusted sample solution S1 for about 20 minutes by an ultraviolet lamp 42 to oxidatively decompose nitrogen compounds to nitrate ions and decompose potassium peroxodisulfate in the solution into potassium sulfate. Then, after decomposing all potassium persulfate, nitrate ions are reduced to nitrite ions by further irradiating with ultraviolet rays for 5 to 20 minutes. After these reactions are completed, the measuring unit control unit 61d outputs a drive signal to the pulse motor 12c to measure and collect a predetermined amount (a + b + c + d) of the reaction sample solution S2 with the syringe pump 12, and then pulse again. By outputting a drive signal to the motor 12c, a predetermined amount of hydrochloric acid of the container 8 is added in the syringe 12a to generate a predetermined amount (a + b + c + d + e) of the adjusted sample solution S3.

Next, the measuring unit control unit 61d introduces a predetermined amount (a + b + c + d + e) of the adjusted sample liquid S3 from the syringe pump 12 into the measuring cell 53 by outputting a drive signal to the pulse motor 12c. At this time, the acquisition unit 61a emits a laser beam from the semiconductor laser element 51 to detect the light intensity change I (L) by the photodiode 52. Next, the determination unit 61c determines whether or not a predetermined amount (a + b + c + d + e) of the adjusted sample solution S3 is contained in the measurement cell 53 based on the detected light intensity change I (L).

Then, when it is determined that a predetermined amount (a + b + c + d + e) of the adjusted sample solution S3 is contained, the absorbance calculation unit 61b measures the absorbance at 220 nm based on the detected light intensity I to obtain the total nitrogen content of the sample solution S. The density is calculated and stored in the memory 63. On the other hand, when it is determined that the adjusted sample liquid S3 of a predetermined amount (a + b + c + d + e) is not contained, the determination unit 61c displays a warning on the display device 62.

As described above, according to the online total nitrogen measuring device 1 having the configuration according to the present invention, it is possible to detect an abnormal state such as liquid shortage or liquid leakage at an early stage.

<Other embodiments>
<1> The above-mentioned online total nitrogen measuring device 1 shows a configuration for determining whether or not a predetermined amount (a + b + c + d + e) of the adjusted sample liquid S3 is contained in the measuring cell 53. Instead, the reactor 40 is used. A light source unit and a detection unit may be provided in the reactor 40 to determine whether or not a predetermined amount (a + b + c + d) of the adjusted sample liquid S1 is contained in the reactor 40.

<2> In the above-described embodiment, the configuration when the present invention is applied to the online total nitrogen measuring device 1 has been described, but instead, it may be applied to other water quality analyzers.

The present invention can be used in a water quality analyzer such as a total nitrogen measuring device that measures the total nitrogen concentration in a sample solution.

1: Online total nitrogen measuring device (water quality analyzer)
51: Semiconductor laser element (light source unit)
52: Photodiode (detector)
53: Measurement cell (sample container)
53e: Sample liquid introduction port 61c: Judgment unit

Claims (3)

A sample container in which a sample solution inlet is formed at the bottom and the sample solution is introduced from the sample solution inlet, and a sample container.
A light source unit that irradiates the sample container with light,
A detection unit that detects the light transmitted through the sample container and
A water quality analyzer including a memory for storing a change in light intensity with respect to a reference liquid feed amount detected by the detection unit when a predetermined amount of sample liquid is introduced into the sample container.
When the sample liquid is contained in the sample container, the change in light intensity with respect to the measured amount of liquid sent detected by the detection unit is compared with the change in light intensity for reference, and the change in light intensity for reference is compared in the sample container. A water quality analyzer comprising a determination unit for determining whether or not a predetermined amount of sample liquid is contained. The water quality analyzer according to claim 1, wherein the sample container is a measurement cell for analyzing the sample solution or a reaction container for reacting the sample solution. A measuring unit that measures the sample liquid and
A valve to which the sample liquid introduction port and the measuring unit are connected,
The water quality analyzer according to claim 1 or 2, further comprising a measuring unit and a control unit that controls the valve.

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