JP7252044B2 - Concentration analyzer - Google Patents

Description

The present invention relates to a concentration analyzer for analyzing the hydrogen peroxide concentration and dissolved oxygen concentration in sample water.

2. Description of the Related Art Conventionally, ultrapure water from which impurities are highly removed has been used as a cleaning liquid for cleaning electronic components such as semiconductor wafers and glass substrates in the manufacturing processes of semiconductor devices and liquid crystal devices. Ultrapure water is generally produced by sequentially treating raw water (river water, groundwater, industrial water, etc.) with a pretreatment system, a primary pure water system, and a secondary pure water system (subsystem).

In many subsystems, an ultraviolet oxidizer is installed to irradiate the water to be treated with ultraviolet rays in order to decompose the total organic carbon (TOC) contained in the water to be treated (primary pure water produced in the primary pure water system). It is It is known that a small amount of hydrogen peroxide is generated in the process of the ultraviolet oxidation treatment in the ultraviolet oxidation apparatus. This causes the formation of a natural oxide film on the surface of the metal and the corrosion of fine wiring. Therefore, it is required to reduce the hydrogen peroxide in the treated water (ultra-pure water) as much as possible in the subsystem including the ultraviolet oxidation device. are required to do so.

In response to such demands, Patent Literatures 1 and 2 describe concentration analyzers capable of analyzing the concentration of hydrogen peroxide in sample water simply and with high accuracy. Utilizing the fact that hydrogen peroxide decomposes into water and oxygen, this analyzer compares the dissolved oxygen concentration in the sample water before and after hydrogen peroxide is decomposed by the hydrogen peroxide decomposing means. A hydrogen peroxide concentration is calculated. In addition, since this analyzer measures the dissolved oxygen concentration in the sample water before the hydrogen peroxide is decomposed by the hydrogen peroxide decomposition means, analysis of the dissolved oxygen concentration in the sample water, which has conventionally been required to be appropriately controlled, is necessary. is also possible.

JP 2005-274386 A JP 2012-63303 A

By the way, some hydrogen peroxide decomposing means not only decompose hydrogen peroxide into water and oxygen (2H ₂ O ₂ →2H ₂ O + O ₂ ), such as catalysts containing platinum group metals, but also hydrogen coexistence Some react with oxygen below to produce water (2H ₂ +O ₂ →2H ₂ O). Therefore, if the sample water contains not only hydrogen peroxide but also hydrogen, the oxygen generated by decomposition of the hydrogen peroxide reacts with the hydrogen and is consumed. As a result, the concentration of oxygen generated by the decomposition of hydrogen peroxide cannot be measured accurately, and the concentration of hydrogen peroxide in the sample water cannot be accurately calculated. On the other hand, as described in Patent Documents 1 and 2, it is conceivable to remove the hydrogen in advance by installing a degassing means such as a gas separation membrane before the hydrogen peroxide decomposition means. . However, in that case, the oxygen originally contained in the sample water is also removed, making it difficult to analyze the dissolved oxygen concentration at the same time as analyzing the hydrogen peroxide concentration in the sample water with high accuracy. In order to simultaneously analyze the dissolved oxygen concentration with one device, it is conceivable to add a separate dissolved oxygen meter for that purpose, but this is preferable because it leads to an increase in the number of relatively expensive dissolved oxygen meters. do not have.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a concentration analyzer capable of highly accurately analyzing not only the concentration of hydrogen peroxide but also the concentration of dissolved oxygen in sample water while suppressing an increase in cost.

In order to achieve the above object, the concentration analyzer of the present invention is a concentration analyzer for analyzing the concentration of hydrogen peroxide and the concentration of dissolved oxygen in sample water sampled from a predetermined position of a water treatment system. A first pipe connected to and through which the sample water flows, a second pipe connected to a predetermined position and through which the sample water flows, and a desorption device provided in the first pipe for removing at least dissolved hydrogen in the sample water A gas means, a hydrogen peroxide decomposition means provided in a first pipe downstream from the degassing means for decomposing hydrogen peroxide in the sample water, and a first pipe between the degassing means and the hydrogen peroxide decomposition means. and a third pipe connecting the second pipe, and a first concentration measuring means provided in the first pipe on the downstream side of the hydrogen peroxide decomposition means and measuring the dissolved oxygen concentration of the sample water and a second concentration measuring means provided in the second pipe on the downstream side of the connecting portion between the second pipe and the third pipe for measuring the dissolved oxygen concentration of the sample water, and a first concentration measuring means. and a calculation means for calculating the concentration of hydrogen peroxide in the sample water based on the measurement result of the second concentration measurement means and the measurement result of the second concentration measurement means, the first concentration measurement means passing through the first pipe to measure the dissolved oxygen concentration of the sample water that has flowed through the first supply route passing through the degassing means and the hydrogen peroxide decomposing means, and the second concentration measuring means measures , the dissolved oxygen in the sample water that has flowed through the second supply route from the third pipe to the second pipe without passing through the degassing means via the first pipe and without passing through the hydrogen peroxide decomposition means and a third concentration that is the dissolved oxygen concentration of the sample water that has flowed through the third supply route that does not pass through the degassing means and the hydrogen peroxide decomposition means via the second pipe. and are separately measured, and the calculation means is based on the difference between the first density measurement value obtained by the first density measurement means and the second density measurement value obtained by the second density measurement means. to calculate the concentration of hydrogen peroxide in the sample water .

In such a concentration analyzer, sampled water is supplied to the first concentration measuring means through the first supply route including the degassing means, and is supplied to the second concentration measuring means through the second supply route also including the degassing means. It is supplied to the concentration measuring means. Therefore, even if the sample water contains hydrogen, the oxygen generated by the decomposition of hydrogen peroxide will not react with the hydrogen and be consumed, and the hydrogen peroxide concentration in the sample water can be determined with high accuracy. analysis becomes possible. Further, by circulating the collected sample water through the third supply route, it is also possible to measure the concentration of oxygen originally contained in the sample water (third concentration) by the second concentration measuring means.

As described above, according to the present invention, it is possible to provide a concentration analyzer capable of highly accurately analyzing not only the hydrogen peroxide concentration in sample water but also the dissolved oxygen concentration while suppressing an increase in cost.

1 is a schematic configuration diagram of a concentration analyzer according to a first embodiment of the present invention; FIG. FIG. 4 is a schematic configuration diagram of a concentration analyzer according to a second embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The concentration analyzer of the present invention is a method for measuring the concentration of water to be treated (primary pure water produced in the primary pure water system) or treated water (ultrapure water) in a secondary pure water system (subsystem) of an ultrapure water production apparatus. It is preferably used for analyzing hydrogen oxide concentration and dissolved oxygen concentration. However, the present invention is not limited to this, and water sampled from predetermined positions in various water treatment systems can be analyzed. Examples of sample water targeted by the present invention include used treated water (ultra-pure water) collected from points of use, so-called functional water such as hydrogen water, water to be treated or treated water in wastewater treatment equipment. And so on.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a concentration analyzer according to a first embodiment of the present invention. The illustrated configuration is merely an example, and does not limit the present invention.

The concentration analyzer 10 is connected via a sampling pipe L10 to a main pipe L1 through which sample water to be analyzed flows, and analyzes the hydrogen peroxide concentration and dissolved oxygen concentration in the sample water sampled through the sampling pipe L10. be. The concentration analyzer 10 has a degassing device 1 , a hydrogen peroxide decomposition device 2 , two concentration measuring devices 3 a and 3 b , a switching device 4 and an arithmetic device 5 . The concentration analyzer 10 may also have a display device such as a monitor and an output device such as a printer in order to display and print various analysis results (measurement results and calculation results) in real time. In addition, the main pipe L1 is provided with a liquid delivery device (not shown) such as a pump for circulating the sample water upstream from the portion to which the sampling pipe L10 is connected. , the sample water is also supplied to the concentration analyzer 10 . Therefore, it is basically not necessary to provide a liquid transfer device such as a pump near the concentration analyzer 10, but if necessary, a liquid transfer device may be provided, for example, in the sampling pipe L10. A valve for controlling the supply of sample water to the concentration analyzer 10 may be provided in the sampling pipe L10.

A deaerator (deaerator) 1 is provided in the first branch pipe L11 of the two branch pipes L11 and L12 branched from the sampling pipe L10. The degassing device 1 removes dissolved hydrogen in the sample water, thereby reducing the reaction between oxygen and hydrogen that occurs when hydrogen peroxide is decomposed in the hydrogen peroxide decomposing device 2, as will be described later. can be suppressed. The deaerator 1 can also remove dissolved oxygen in the sample water. This makes it possible to reduce the background concentration of dissolved oxygen (blank value) to 100 μg/L or less, preferably 10 μg/L or less, which is particularly useful in microanalysis of hydrogen peroxide concentration at the μg/L level. As the degassing device 1, for example, one having a gas separation membrane can be used.

A hydrogen peroxide decomposing device (hydrogen peroxide decomposing means) 2 is provided downstream of the degassing device 1 in the first branch pipe L11. The hydrogen peroxide decomposition device 2 includes a platinum group metal supported catalyst in which a platinum group metal is supported on a carrier. The platinum group metal-supported catalyst is packed in a container (column), for example, and has the function of decomposing hydrogen peroxide into water and oxygen by contact with sample water containing hydrogen peroxide (2H ₂ O ₂ → _2H2O + _O2 ).

Palladium is preferably used as the platinum group metal used in the supported platinum group metal catalyst because it has excellent catalytic activity and is relatively inexpensive. As the support for the platinum group metal-supported catalyst, a general granular anion exchange resin can be used, but from the viewpoint of adjustment and reactivity of the catalyst, it is preferable to use an anion exchanger, especially a monolithic organic porous It is more preferred to use a high quality anion exchanger. The monolithic organic porous anion exchanger is obtained by introducing ion exchange groups into the skeleton of the monolithic organic porous material, and is capable of passing water at a space velocity exceeding 2000 h ⁻¹ . Therefore, for example, even if air (oxygen) is mixed intermittently or continuously in the hydrogen peroxide decomposition device 2, or if air remains in the hydrogen peroxide decomposition device 2 when the device is started up, the air Some or all of it can be quickly swept downstream. As a result, it is possible to suppress the deterioration of the analysis accuracy due to the mixture of air, and shorten the start-up time. The use of the monolithic organic porous anion exchanger is also advantageous in that it facilitates miniaturization of the hydrogen peroxide decomposition device 2 . A specific example of the monolithic organic porous anion exchanger will be described later.

The material of the container (column) in which the platinum group metal-supported catalyst is packed is not particularly limited, but preferably has a low oxygen permeability and excellent durability. A transparent one is preferable so that the presence or absence of the film can be confirmed. Such materials include, for example, acrylic, vinyl chloride, polycarbonate, and the like.

The two concentration measuring devices 3a and 3b measure the dissolved oxygen concentration in the sample water. and a second concentration measuring device 3b provided in the second branch pipe L12. Known dissolved oxygen meters can be used as the first and second concentration measuring devices 3a and 3b, respectively. In this case, it is preferable to use dissolved oxygen meters of the same model and lot in order to reduce individual differences and improve analysis accuracy.

The concentration analyzer 10 has a sampling pipe L10 and two branch pipes for supplying the sample water flowing through the main pipe L1 to the two concentration measurement devices 3a and 3b via one of three supply routes. A connection pipe L21 is provided in addition to L11 and L12. The connecting pipe L21 is a portion of the first branch pipe L11 downstream of the degassing device 1 and upstream of the hydrogen peroxide decomposition device 2, and a second branch pipe L12 of the second concentration measuring device. 3b is connected to the upstream portion.

Thus, the four pipes L10 to L12, L21 form the three supply routes described above. The first supply routes L10 and L11 are routes passing through the degassing device 1 and the hydrogen peroxide decomposition device 2 from the sampling pipe L10 via the first branch pipe L11. The second supply routes L10, L11, L21, L12 pass from the sampling pipe L10 via the first branch pipe L11 to the degassing device 1, do not pass through the hydrogen peroxide decomposition device 2, and from the connecting pipe L21 to the second 2 branch pipe L12. The third supply routes L10 and L12 are routes that lead from the sampling pipe L10 to the second branch pipe L12 and do not pass through the deaerator 1 and the hydrogen peroxide decomposition device 2 . The first concentration measuring device 3a is on the first supply paths L10, L11, and the second concentration measuring device 3b is on the second supply paths L10, L11, L21, L12 and on the third are on the supply paths L10 and L12 of the

Therefore, the first concentration measuring device 3a is used for the sample water that has flowed through the first supply paths L10 and L11. It measures the first concentration, which is the dissolved oxygen concentration of the sample water. Further, the second concentration measuring device 3b measures sample water that has flowed through the second supply paths L10, L11, L21, and L12, that is, sample water from which dissolved hydrogen has been removed by the degassing device 1, and which is hydrogen peroxide. A second concentration, which is the concentration of dissolved oxygen in the sample water in which the hydrogen peroxide is not decomposed by the decomposing device 2, is measured. Furthermore, the second concentration measuring device 3b also measures the third concentration, which is the dissolved oxygen concentration of the sample water flowing through the third supply paths L10 and L12, that is, the sample water flowing through the main pipe L1. .

A switching device (switching means) 4 switches the sample water supply route to the second concentration measuring device 3b. That is, the switching device 4 switches the sample water supply route to the second concentration measuring device 3b between the second supply routes L10, L11, L21, L12 and the third supply routes L10, L12. There are two on-off valves 41 and 42 . The first on-off valve 41 is provided on the connection pipe L21, and the second on-off valve 42 is located upstream of the connection between the second branch pipe L12 and the connection pipe L21 in the second branch pipe L12. is provided. With this switching device 4, the concentration measurement by the first and second concentration measuring devices 3a and 3b can be performed in the first measurement mode for analyzing the concentration of hydrogen peroxide in the sample water, and in the hydrogen peroxide concentration in the sample water. It becomes possible to switch to a second measurement mode for analyzing concentration and dissolved oxygen concentration.

In the first measurement mode, the first on-off valve 41 is opened and the second on-off valve 42 is closed. As a result, sample water is supplied to the first concentration measuring device 3a through the first supply paths L10 and L11, and the sample water is supplied to the second concentration measuring device 3b through the second supply paths L10, L11, L21 and L12. Sample water is supplied through Thus, the first density is measured by the first density measuring device 3a, and the second density is measured by the second density measuring device 3b. As a result, the arithmetic device 5 calculates the concentration of hydrogen peroxide in the sample water, as will be described later.

On the other hand, in the second measurement mode, the first on-off valve 41 is closed and the second on-off valve 42 is opened. As a result, the sample water is supplied to the first concentration measuring device 3a through the first supply paths L10 and L11, and the sample water is supplied to the second concentration measuring device 3b through the third supply paths L10 and L12. supplied. Thus, the first concentration is measured by the first concentration measuring device 3a, and the third concentration, that is, the concentration of oxygen originally contained in the sample water (dissolved oxygen concentration) is measured by the second concentration measuring device 3b. be. Also in the second measurement mode, by using the second concentration measurement value obtained by the second concentration measuring device 3b in the first measurement mode, the calculation device 5 can detect excess concentration in the sample water, as will be described later. A hydrogen oxide concentration is calculated.

The computing device 5 determines the concentration of hydrogen peroxide in the sample water based on the difference between the first concentration value measured by the first concentration measuring device 3a and the second concentration value measured by the second concentration measuring device 3b. is calculated. That is, from the first density DO ₁ measured by the first density measuring device 3a and the second density DO ₂ measured by the second density measuring device 3b, the difference ΔDO=DO ₁ -DO ₂ Calculate Here, the calculated difference ΔDO coincides with the increase in oxygen concentration resulting from oxygen generated by decomposition of hydrogen peroxide (2H ₂ O ₂ →2H ₂ O+O ₂ ) in the hydrogen peroxide decomposition device 2 . Therefore, the hydrogen peroxide concentration C _HP =(68/32) ΔDO in the sample water is calculated from the calculated difference, that is, the increment ΔDO of the oxygen concentration. Here, the coefficient 68 is the molecular weight of hydrogen peroxide on the left side of the hydrogen peroxide decomposition reaction formula, and the coefficient 32 is the molecular weight of oxygen on the right side.

The platinum group metal-supported catalyst of the hydrogen peroxide decomposition device 2 not only decomposes the hydrogen peroxide in the sample water, but also has the function of reacting with oxygen in the presence of hydrogen to generate water (2H ₂ + O ₂ → 2H ₂ O). Therefore, when the sample water containing hydrogen peroxide and hydrogen is supplied to the hydrogen peroxide decomposition device 2, the oxygen generated by the decomposition of the hydrogen peroxide reacts with the hydrogen and is consumed, and the calculated difference ΔDO However, it is possible that the increase in oxygen concentration due to the oxygen actually produced is underestimated. Such a situation may occur, for example, when treated water in a subsystem of an ultrapure water production apparatus including an ultraviolet oxidizer is used as sample water. In other words, it is known that not only a small amount of hydrogen peroxide but also a small amount of hydrogen is generated in the ultraviolet oxidation process in the ultraviolet oxidation device, and the treated water in the subsystem contains not only hydrogen peroxide but also hydrogen. There is a possibility that

However, in the concentration analyzer 10 of the present embodiment, the collected sample water is supplied to the first concentration measurement device 3a via the first supply paths L10 and L11 including the degassing device 1, and is also degassed. It is supplied to the second concentration measuring device 3b via the second supply paths L10, L11, L21, L12 including the gas device 1. Therefore, even if the sample water flowing through the main pipe L1 contains hydrogen, such hydrogen is removed by the degassing device 1, so that the oxygen generated by the decomposition of the hydrogen peroxide reacts with the hydrogen. It will no longer be consumed. As a result, there is no possibility that the calculated difference ΔDO will be estimated lower than the actual increase in oxygen, and it becomes possible to calculate the concentration of hydrogen peroxide in the sample water with higher accuracy. Since the concentration analyzer 10 of this embodiment is equipped with the degassing device 1 that removes hydrogen that may be contained in the sample water, it is a sub of an ultrapure water production device that does not have degassing means such as a gas separation membrane. It is particularly useful when the treated water in the system is to be analyzed.

In addition, according to the present embodiment, the second concentration measuring device 3b used for analyzing the concentration of hydrogen peroxide in the sample water causes the collected sample water to flow through the third supply paths L10 and L12. , it is also possible to measure the concentration of oxygen originally contained in the sample water (dissolved oxygen concentration). The sample water whose concentration has been measured is discharged to the outside from the branch pipes L11 and L12, respectively, but this embodiment is advantageous in that wastewater treatment is facilitated because no reagent is used for concentration measurement. is.

Both the first measurement mode and the second measurement mode are preferably performed continuously. As a result, the hydrogen peroxide concentration can be calculated using the moving average value for a certain period of time even when the measured values vary greatly, and as a result, the analysis accuracy of the hydrogen peroxide concentration can be improved. Further, switching between the first measurement mode and the second measurement mode may be performed at a predetermined frequency, or the first measurement mode is normally executed and the first measurement mode is switched as necessary. A second measurement mode may be performed between . When switching between the first measurement mode and the second measurement mode at a predetermined frequency, the frequency is not particularly limited. preferably not too much. In each measurement mode, the actual concentration measurement is preferably performed after a certain period of time has passed since the supply of the sample water was switched, and each measurement value has stabilized.

Further, it is preferable to calibrate the dissolved oxygen meters used in the first and second concentration measuring devices 3a and 3b at an arbitrary frequency. Thereby, the measurement accuracy of each densitometer and the analysis accuracy of the hydrogen peroxide concentration and the dissolved oxygen concentration can be improved. As a method for calibrating the dissolved oxygen meter, atmospheric calibration and zero point calibration, which are generally used for calibrating the dissolved oxygen meter, can be used. There is no particular limit to the frequency of calibration, but if the frequency is more than once a day, it is troublesome because calibration is frequently performed, and if it is less than once a year, the frequency of calibration is too low. value becomes unreliable. Therefore, the frequency of calibration is preferably once a day to once a year, more preferably once a week to once a year.

The dissolved oxygen meters used in the first and second concentration measuring devices 3a and 3b are adjusted to minimize errors within a predetermined flow rate range. Therefore, it is preferable that the flow rate of sample water supplied to each densitometer is adjusted within such a flow rate range. Therefore, it is preferable that each of the branch pipes L11 and L12 is provided with flow rate adjusting means 11 and 12 for adjusting the flow rate of the sample water flowing therethrough. There are no particular restrictions on the configuration of each of the flow rate adjusting means 11 and 12, and for example, flow rate adjusting means each comprising a flow meter and a flow rate adjusting valve can be used. Moreover, the installation positions of the flow rate adjusting means 11 and 12 are preferably downstream of the concentration measuring devices 3a and 3b because there is a risk that air (oxygen) may enter through joints of pipes or the like. In addition to the flow rate adjusting means 11 and 12, the branch pipes L11 and L12 may be arbitrarily provided with a well-known configuration (for example, an alarm device) used for process control.

The first supply paths L10, L11 and the second supply paths L10, L11, L21, L12 have no water flow conditions such as pressure loss because the hydrogen peroxide decomposition device 2 is not installed in the second branch pipe L12. are different from each other. Therefore, such a difference in water flow conditions may affect the analysis accuracy of the hydrogen peroxide concentration. Therefore, in order to match the water flow conditions of the first supply routes L10, L11 with the water flow conditions of the second supply routes L10, L11, L21, L12, the second branch pipe L12 A dummy container (column) may be installed downstream from the connecting portion between the pipe L12 and the connection pipe L21. There are no particular restrictions on the configuration of the dummy column, and for example, it has the same configuration as the hydrogen peroxide decomposition device 2 except that it does not have hydrogen peroxide decomposition capability (no platinum group metal is supported on the carrier). can be installed.

The materials for the sampling pipe L10, the branch pipes L11 and L12, and the connection pipe L21 are preferably those with low gas permeability, particularly those with low oxygen permeability and little elution of impurities. Examples of such materials include stainless steel and polyamide resin. In addition, when stainless steel is used as the material for each pipe, joints such as elbows and tee are used to prevent air (oxygen) from entering through the joints. It is preferably made by welding or bending instead.

In this embodiment, the first concentration measuring device 3a functions as first concentration measuring means for measuring the first concentration, and the second concentration measuring device 3b measures the second concentration and the third concentration. and the arithmetic device 5 functions as arithmetic means for calculating the concentration of hydrogen peroxide in the sample water based on these measured values. The configuration of the concentration measuring means and computing means of 2 is not limited to this. For example, instead of the concentration measuring devices (dissolved oxygen meters) 3a and 3b, a detector for detecting the current flowing between the electrodes in proportion to the dissolved oxygen concentration in the sample water based on the diaphragm electrode method is provided, and the detection result is , the calculation device 5 may convert the dissolved oxygen concentration and calculate the hydrogen peroxide concentration. That is, the computing device 5 may have the functions of the first density measuring means, the second density measuring means, and the computing means.

In the illustrated configuration, two branch pipes L11 and L12 are connected to the main pipe L1 via the sampling pipe L10, but each may be directly connected to the main pipe L1. However, if the sampling positions of the sample water differ greatly, the water quality conditions such as the dissolved oxygen concentration may differ. preferably connected.

(Second embodiment)
FIG. 2 is a schematic configuration diagram of a concentration analyzer according to a second embodiment of the present invention. In the following, configurations similar to those of the first embodiment are denoted by the same reference numerals in the drawings, description thereof is omitted, and only configurations different from those of the first embodiment are described.

As described above, in order to improve the measurement accuracy of the dissolved oxygen meters used in the first and second concentration measuring devices 3a and 3b, it is preferable to perform calibration at any frequency. However, in microanalyses of hydrogen peroxide concentrations at the μg/L level, minute individual differences among densitometers may not be negligible. In particular, when the hydrogen peroxide concentration is calculated based on the difference between the measured values of two dissolved oxygen meters, such minute individual differences may have a greater effect.

Therefore, in the present embodiment, the correction value acquisition step (third measurement mode) is performed at any frequency between the above-described concentration analysis steps (first and second measurement modes), which are normal operations of the concentration analyzer 10. is executed in In the correction value obtaining step, a correction value for compensating for individual differences in dissolved oxygen meters (first and second concentration measuring devices 3a and 3b) is obtained. in the concentration analysis step, the first concentration DO ₁ measured by the first concentration measuring device 3a, the second concentration DO ₂ measured by the second concentration measuring device 3b, and the difference ΔDO (=DO ₁ − DO ₂ ) is corrected. Then, this corrected difference matches the increased amount of oxygen concentration derived from oxygen generated by the decomposition of hydrogen peroxide.

In order to execute this correction value acquisition process, the concentration analyzer 10 of the present embodiment has, in addition to the connection pipe (first connection pipe) L21 of the first embodiment, another connection downstream thereof. A pipe (second connection pipe) L22 is provided. The second connection pipe L22 is a portion of the first branch pipe L11 downstream of the hydrogen peroxide decomposition device 2 and upstream of the first concentration measuring device 3a, and a portion of the second branch pipe L12. , downstream of the connecting portion of the second branch pipe L12 and the first connection pipe L21 and upstream of the second concentration measuring device 3b. The material and processing method of the second connection pipe L22 are preferably the same as those of the sampling pipe L10, the branch pipes L11 and L12, and the first connection pipe L21.

A switch 4 switches between the concentration analysis process and the correction value analysis process. For this purpose, the switching device 4 has a third on-off valve 43 and a fourth on-off valve 44 in addition to the first on-off valve 41 and the second on-off valve 42 . The third on-off valve 43 is provided in the second connection pipe L22, and the fourth on-off valve 44 is provided in the first branch pipe L11 on the downstream side of the hydrogen peroxide decomposition device 2 and in the first branch pipe L11. It is provided on the upstream side of the connecting portion between the branch pipe L11 and the second connection pipe L22. In the concentration analysis step (first measurement mode and second measurement mode) of this embodiment, the third on-off valve 43 is closed and the fourth on-off valve 44 is opened in any measurement mode.

On the other hand, in the correction value obtaining step, the first and second on-off valves 41 and 42 are closed, and the third and fourth on-off valves 43 and 44 are opened. As a result, the sample water is supplied to the first concentration measuring device 3a through the first supply routes L10 and L11, and the sample water flowing through the first supply routes L10 and L11 is also supplied to the second concentration measuring device 3b. Water is supplied from the second connecting pipe L22 through the second branch pipe L12. Thus, the first density is measured simultaneously by the first density measuring device 3a and the second density measuring device 3b. Alternatively, in the correction value obtaining step, the first and fourth on-off valves 41 and 44 are closed and the second and third on-off valves 42 and 43 are opened. As a result, the sample water that has flowed through the third supply paths L10 and L12 is supplied to the first concentration measuring device 3a from the second connection pipe L22 through the first branch pipe L11, and the second concentration measuring device 3b is also supplied with the sample water that has flowed through the second supply paths L10 and L12. In this way, the third concentration is simultaneously measured by the first concentration measuring device 3a and the second concentration measuring device 3b.

When the first concentration or the third concentration is simultaneously measured by the first concentration measuring device 3a and the second concentration measuring device 3b, the computing device 5 outputs the measured value M1 of the first concentration measuring device 3a, The difference ΔM=M1−M2 is calculated from the measured value M2 of the second concentration measuring device 3b. The difference ΔM thus calculated is stored in the computing device 5 as a correction value for compensating for individual differences in the dissolved oxygen meters of the first and second concentration measuring devices 3a and 3b, and a correction value obtaining step is executed. updated every

In the concentration analysis step of this embodiment, the difference ΔDO is corrected based on the correction value ΔM obtained in the correction value obtaining step. That is, from the correction value ΔM and the difference ΔDO, the oxygen concentration increment ΔDO ₀ =ΔDO−ΔM derived from the oxygen generated by the decomposition of hydrogen peroxide is calculated. Then, as described above, the hydrogen peroxide concentration C _HP in the sample water is calculated from the calculated increase in oxygen concentration ΔDO ₀ (C _HP =(68/32)ΔDO ₀ ). As a result, the influence of individual differences in the dissolved oxygen meters (the first and second concentration measuring devices 3a and 3b) can be suppressed, and the hydrogen peroxide concentration can be analyzed with higher accuracy.

The correction value acquisition step is executed immediately after the calibration of the densitometer itself as described above, but apart from this, it is also executed at a predetermined frequency. The execution frequency is not particularly limited, but if the frequency is more than once a day, the concentration analysis process is frequently switched to the correction value acquisition process, resulting in a longer period during which the hydrogen peroxide concentration cannot be analyzed. If the frequency is less than once every six months, the frequency of calibration is too low and the reliability of the measured value is poor. Therefore, the frequency of executing the correction value obtaining step is preferably once a day to once every six months, except immediately after calibration of the densitometer itself. It should be noted that the calculation of the actual correction value in the correction value acquisition step is preferably performed after a certain period of time has elapsed since the supply of the sample water was switched, and each measurement value has stabilized. , an average value over a predetermined period of time can also be used.

In the correction value acquisition step, as long as the same kind of sample water is supplied to the first and second concentration measuring devices 3a and 3b, the sample water flowing through the first supply paths L10 and L11 and the third supply Either of the sample waters that have flowed through paths L10 and L12 may be supplied. However, the concentration of oxygen originally contained in the sample water (third concentration) can be monitored even during the execution of the correction value acquisition process, and the sample water flowing through the third supply paths L10, L12 Water is preferably supplied. In the illustrated configuration, the sample water flows in the opposite directions through the second connecting pipe L22 in the two cases described above. Therefore, as the third on-off valve 43 installed in the second connection pipe L22, it is preferable to use a ball valve that has no restriction in the flow direction. Further, in the correction value obtaining step, when it is predetermined that the sample water flowing through the first supply paths L10, L11 is supplied to the first and second concentration measuring devices 3a, 3b, 4 on-off valve 44 can be omitted. As a result, the amount of air (oxygen) entering from the valve can be reduced, and maintenance of the valve can also be reduced.

In the correction value obtaining step, it is preferable to supply sample water at the same flow rate to the dissolved oxygen meters used in the first and second concentration measuring devices 3a and 3b. Therefore, as in the first embodiment, each of the branch pipes L11 and L12 is preferably provided with flow rate adjusting means 11 and 12 for adjusting the flow rate of the sample water flowing therethrough.

(Monolithic anion exchanger)
Here, two kinds of monolithic organic porous anion exchangers will be described as specific examples of monolithic organic porous anion exchangers that are suitably used in the hydrogen peroxide decomposition apparatus 2 of the above-described embodiment. Hereinafter, the monolithic organic porous anion exchanger is simply referred to as "monolithic anion exchanger", and the monolithic organic porous material is also simply referred to as "monolith". A monolithic organic porous intermediate, which is an intermediate (precursor) in the production of a monolith, is also simply referred to as a "monolith intermediate".

[Type A monolithic anion exchanger]
The type A monolithic anion exchanger is obtained by introducing anion exchange groups into a monolith. Cellular macropores overlap each other, and the overlapping portions have an average diameter of 30 to 300 μm, preferably 30 μm, in a water-wet state. It is a continuous macropore structure with openings (mesopores) of up to 200 μm, particularly preferably 40 to 100 μm. The average diameter of the openings of the type A monolith anion exchanger is larger than that of the monolith because the entire monolith swells when the anion exchange groups are introduced into the monolith. If the average diameter of the openings in a wet state is less than 30 μm, the pressure loss during water flow increases, which is not preferable. water) and the monolithic anion exchanger of type A and the supported platinum group metal nanoparticles become insufficient, resulting in poor hydrogen peroxide decomposition properties. The average diameter of the openings of the dry monolith intermediate, the average diameter of the openings of the dry monolith, and the average diameter of the openings of the dry monolith anion exchanger are values measured by mercury porosimetry. do. The average diameter of the apertures of the type A monolith anion exchanger in a water-wet state is a value calculated by multiplying the average diameter of the apertures of the type A monolith anion exchanger in a dry state by the swelling ratio. In addition, the average diameter of the openings of the monolith in a dry state before anion exchange group introduction, and the swelling of the monolithic anion exchanger in a water-wet state with respect to the dry state monolith when anion exchange groups are introduced into the dry monolith. If the ratio is known, the average diameter of the openings of the monolith in the dry state can also be multiplied by the swelling ratio to calculate the average diameter of the openings in the water-wetted Type A monolith anion exchanger.

In the A-type monolithic anion exchanger, in a scanning electron microscope (SEM) image of the cross section of the continuous macropore structure, the skeleton portion area appearing in the cross section is 25 to 50%, preferably 25 to 45%, of the image area. is. If the area of the skeletal portion appearing in the cross section is less than 25% of the image area, the skeletal structure will be thin, and the mechanical strength will decrease, resulting in large deformation of the monolithic anion exchanger, especially when water is passed at a high flow rate. I don't like it because Furthermore, the contact efficiency between the water to be treated and the type A monolithic anion exchanger and the platinum group metal nanoparticles supported on it decreases, which is not preferable because the catalytic effect decreases. It is not preferable because it is too high and the pressure loss increases when water is passed.

Also, the total pore volume of the A-type monolithic anion exchanger is 0.5-5 ml/g, preferably 0.8-4 ml/g. If the total pore volume is less than 0.5 ml/g, the pressure loss during water flow increases, which is not preferable. I don't like it because I can't put it away. On the other hand, when the total pore volume exceeds 5 ml/g, the mechanical strength is lowered, and the type A monolithic anion exchanger is deformed particularly when water is passed at a high flow rate, which is not preferable. Furthermore, the contact efficiency between the water to be treated and the type A monolithic anion exchanger and the platinum group metal nanoparticles supported thereon is lowered, and the catalytic effect is also lowered, which is not preferable. The total pore volume of the monolith intermediate, monolith, and monolith anion exchanger means a value measured by mercury porosimetry. Also, the total pore volume of the monolith intermediate, monolith, and monolith anion exchanger, respectively, is the same in dry and water-wet states.

The pressure loss when water is permeated through the A-type monolithic anion exchanger is represented by the pressure loss when water is passed through a column packed with 1 m of this at a linear water flow velocity (LV) of 1 m / h. It is preferably in the range of 0.001 to 0.1 MPa/m·LV, particularly 0.005 to 0.05 MPa/m·LV.

The type A monolithic anion exchanger has a volumetric anion exchange capacity of 0.4 to 1.0 mgeq/ml in a water-wet state. If the anion exchange capacity per volume is less than 0.4 mg equivalent/ml, the amount of platinum group metal nanoparticles supported per volume decreases, which is not preferable. On the other hand, if the anion exchange capacity per volume exceeds 1.0 mg equivalent/ml, the pressure loss during water passage increases, which is not preferable. The anion exchange capacity per unit weight of the type A monolithic anion exchanger is not particularly limited, but since the anion exchange groups are uniformly introduced to the surface and the inside of the skeleton of the porous body, the anion exchange capacity is 3.5 to 4.5. 5 mg equivalent/g.

In the A-type monolithic anion exchanger, the material constituting the skeleton of the continuous macropore structure is an organic polymer material having a crosslinked structure. Although the crosslink density of the polymer material is not particularly limited, it contains 0.3 to 10 mol%, preferably 0.3 to 5 mol% of crosslinked structural units, based on the total structural units constituting the polymer material. is preferred. If the crosslinked structural unit is less than 0.3 mol %, the mechanical strength is insufficient, and if it exceeds 10 mol %, introduction of the anion exchange group may become difficult, which is not preferred. The type of polymer material is not particularly limited, and examples thereof include aromatic vinyl polymers such as polystyrene. The above polymer may be a polymer obtained by copolymerizing a single vinyl monomer and a cross-linking agent, a polymer obtained by polymerizing a plurality of vinyl monomers and a cross-linking agent, or a blend of two or more types of polymers. may have been Among these organic polymer materials, the ease of forming a continuous macropore structure, the ease of introducing anion-exchange groups, high mechanical strength, and high stability against acids or alkalis make aromatic vinyl polymers cross-linkable. A coalescence is preferred, and styrene-divinylbenzene copolymers and vinylbenzyl chloride-divinylbenzene copolymers are particularly preferred materials.

The anion exchange group of the A type monolithic anion exchanger includes quaternary ammonium groups such as trimethylammonium group, triethylammonium group, tributylammonium group, dimethylhydroxyethylammonium group, dimethylhydroxypropylammonium group and methyldihydroxyethylammonium group. is mentioned.

The introduced anion exchange groups are uniformly distributed not only on the surface of the porous body but also inside the skeleton of the porous body. The phrase "the anion-exchange groups are uniformly distributed" as used herein means that the anion-exchange groups are uniformly distributed on the surface and inside the skeleton at least on the order of μm. The distribution of anion-exchange groups can be confirmed relatively easily by using an electron probe microanalyzer (EPMA) after ion-exchanging counter anions to chloride ions, bromide ions, or the like. In addition, when the anion exchange groups are uniformly distributed not only on the surface of the monolith but also inside the skeleton of the porous body, the physical properties and chemical properties of the surface and the inside can be made uniform, resulting in swelling and shrinkage. Improves durability against

In the A-type monolith anion exchanger, since an anion exchange group is introduced into the monolith of the bone, it swells as much as 1.4 to 1.9 times that of the monolith of the bone. Therefore, even if the opening diameter of the monolithic monolith is small, the opening diameter of the monolithic ion exchanger generally increases by the above magnification. Further, even if the opening diameter increases due to swelling, the total pore volume does not change. Therefore, the A-type monolithic ion exchanger has high mechanical strength because it has a bone skeleton in spite of its significantly large opening diameter.

[B type monolithic anion exchanger]
The B-type monolithic anion exchanger is composed of an aromatic vinyl polymer containing 0.3 to 5.0 mol% of crosslinked structural units among all structural units into which anion exchange groups have been introduced, and has an average thickness in a water-wet state. A co-continuous structure comprising a three-dimensionally continuous skeleton of 1 to 60 μm and three-dimensionally continuous pores having an average diameter of 10 to 100 μm in a water-wet state between the skeletons, It has a volume of 0.5 to 5 ml/g, an ion exchange capacity per volume in a water-wet state of 0.3 to 1.0 mg equivalent/ml, and anion exchange groups are uniform in the porous ion exchanger. distributed in

The B-type monolithic anion exchanger has a three-dimensionally continuous skeleton having an anion exchange group introduced therein and having an average thickness of 1 to 60 μm, preferably 3 to 58 μm in a wet state, and an average diameter between the skeletons. It is a co-continuous structure consisting of three-dimensionally continuous pores of 10 to 100 μm, preferably 15 to 90 μm, particularly preferably 20 to 80 μm in a water-wet state. That is, the co-continuous structure is a structure in which a continuous skeletal phase and a continuous pore phase are intertwined and both are three-dimensionally continuous. Since the continuous pores have higher continuity than conventional open-cell monoliths and particle-aggregated monoliths, and there is no bias in the size of the pores, extremely uniform ion adsorption behavior can be achieved. In addition, since the skeleton is thick, the mechanical strength is high.

The skeleton thickness and pore diameter of the B-type monolith anion exchanger are larger than those of the monolith because the entire monolith swells when the anion exchange groups are introduced into the monolith. Become. These continuous pores have higher continuity than conventional open-cell monolithic anion exchangers and particle-aggregated monolithic anion exchangers, and there is no bias in the size of the pores, resulting in extremely uniform anion adsorption. behavior can be achieved. If the average diameter of the three-dimensionally continuous pores is less than 10 μm in a water-wet state, the pressure loss during water passage increases, which is not preferable. Contact with the organic porous anion exchanger becomes insufficient, and as a result, dissolved oxygen in the water to be treated becomes insufficiently removed, which is not preferable. In addition, if the average thickness of the skeleton is less than 1 μm in a water-wet state, in addition to the drawback that the anion exchange capacity per volume decreases, the mechanical strength decreases, especially when water is passed at a high flow rate. This type of monolithic anion exchanger is greatly deformed, which is not preferable. Furthermore, the contact efficiency between the water to be treated and the B-type monolithic anion exchanger is lowered, and the catalytic effect is lowered, which is not preferable. On the other hand, if the thickness of the skeleton exceeds 60 μm, the skeleton becomes too thick, which is not preferable because the pressure loss increases when water flows.

The average diameter of the pores of the continuous structure in a water-wet state is a value calculated by multiplying the average diameter of the pores of the dry monolithic anion exchanger measured by the mercury porosimetry by the swelling ratio. In addition, the average pore diameter of the dry monolith before anion exchange group introduction, and the water-wet B type monolith anion exchanger with respect to the dry monolith when anion exchange groups are introduced into the dry monolith If the swelling ratio is known, the average pore diameter of the monolith in the dry state can be multiplied by the swelling ratio to calculate the average pore diameter of the water-wet type B monolith anion exchanger. In addition, the average thickness of the skeleton of the continuous structure in a water-wet state is obtained by observing the B-type monolithic anion exchanger in a dry state with an SEM at least three times, and measuring the thickness of the skeleton in the obtained image. and the mean value is multiplied by the swelling ratio. In addition, the average thickness of the skeleton of the monolith in a dry state before anion exchange group introduction, and the monolithic B type anion exchanger in a water-wet state with respect to the dry state monolith when anion exchange groups are introduced into the dry state monolith If the swelling rate is known, the average thickness of the skeleton of the monolith in the dry state can be multiplied by the swelling rate to calculate the average thickness of the skeleton of the B-type monolith anion exchanger in the water-wet state. The skeleton is rod-shaped and has a circular cross-sectional shape, but may include a cross-section with a different diameter such as an elliptical cross-sectional shape. The thickness in this case is the average of the minor axis and the major axis.

Also, the total pore volume of the B-type monolithic anion exchanger is 0.5-5 ml/g. If the total pore volume is less than 0.5 ml/g, the pressure loss during water flow increases, which is not preferable. I don't like it because On the other hand, if the total pore volume exceeds 5 ml/g, the anion exchange capacity per volume is lowered, the amount of platinum group metal nanoparticles supported is also lowered, and the catalytic effect is lowered, which is not preferable. Moreover, the mechanical strength is lowered, and the type B monolithic anion exchanger is greatly deformed particularly when water is passed at a high flow rate, which is not preferable. Furthermore, the contact efficiency between the water to be treated and the type B monolithic anion exchanger is lowered, and the effect of decomposing hydrogen peroxide is also lowered, which is not preferable. If the three-dimensionally continuous pore size and total pore volume are within the above range, contact with the water to be treated is extremely uniform, the contact area is large, and water can flow under low pressure loss. Become. It should be noted that the total pore volume of the monolith intermediate, the monolith, and the monolith anion exchanger, respectively, are the same in the dry and water-wet states.

The pressure loss when water is permeated through the B-type monolithic anion exchanger is indicated by the pressure loss when water is passed through a column packed with a porous body of 1 m at a linear water flow velocity (LV) of 1 m / h. and the range of 0.001 to 0.5 MPa/m·LV, especially 0.005 to 0.1 MPa/m·LV.

In the B-type monolithic anion exchanger, the material constituting the skeleton of the co-continuous structure contains 0.3 to 5 mol%, preferably 0.5 to 3.0 mol% of crosslinked structural units in all structural units. It is an aromatic vinyl polymer containing and is hydrophobic. If the crosslinked structural unit is less than 0.3 mol %, the mechanical strength is insufficient, and if it exceeds 5 mol %, the structure of the porous body tends to deviate from the co-continuous structure. The type of the aromatic vinyl polymer is not particularly limited, and examples thereof include polystyrene. The above polymer may be a polymer obtained by copolymerizing a single vinyl monomer and a cross-linking agent, a polymer obtained by polymerizing a plurality of vinyl monomers and a cross-linking agent, or a blend of two or more types of polymers. may have been Among these organic polymer materials, styrene-divinylbenzene copolymer is preferred because of its ease of forming a co-continuous structure, ease of introduction of anion-exchange groups, high mechanical strength, and high stability against acid or alkali. and vinylbenzyl chloride-divinylbenzene copolymer are preferred.

The B-type monolithic anion exchanger has an ion exchange capacity of 0.3 to 1.0 mgeq/ml of anion exchange capacity per volume in a water-wet state. Since the B-type monolithic anion exchanger has high continuity and uniformity of three-dimensionally continuous pores, even if the total pore volume is reduced, the pressure loss does not increase so much. Therefore, the anion exchange capacity per volume can be dramatically increased while keeping the pressure loss low. If the anion exchange capacity per volume is less than 0.3 mg equivalent/ml, the amount of platinum group metal nanoparticles supported per volume decreases, which is not preferable. On the other hand, if the anion exchange capacity per volume exceeds 1.0 mg equivalent/ml, the pressure loss during water passage increases, which is not preferable. The anion exchange capacity per unit weight of the B-type monolithic anion exchanger in a dry state is not particularly limited. 5 to 4.5 mg equivalent/g.

Examples of the anion-exchange group for the B-type monolithic anion exchanger are the same as those mentioned in the description of the A-type monolithic anion exchanger. In addition, the distribution state of the anion exchange groups, the meaning of "the anion exchange groups are uniformly distributed", the method for confirming the distribution state of the anion exchange groups, and the anion exchange groups not only on the surface of the monolith but also on the porous surface. The effect of uniform distribution inside the skeleton of the body is also similar to that of the A-type monolithic anion exchanger.

The type of polymer material for the monolith intermediate is the same as the type of polymer material for the monolith intermediate of the A-type monolith anion exchanger, and the description thereof is omitted.

The total pore volume of the monolith intermediate is greater than 16 ml/g and less than or equal to 30 ml/g, preferably greater than 16 ml/g and less than or equal to 25 ml/g. In other words, this monolithic intermediate basically has a continuous macropore structure, but because the openings (mesopores), which are the overlapping portions of macropores and macropores, are remarkably large, the framework that constitutes the monolithic structure changes from the two-dimensional walls to the first order. It has a structure that is extremely close to the original rod-like skeleton. When this is allowed to coexist in the polymerization system, a porous body with a co-continuous structure is formed with the structure of the monolithic intermediate as a mold. If the total pore volume is too small, the structure of the monolith obtained after polymerizing the vinyl monomer will change from a co-continuous structure to a continuous macropore structure, which is not preferable. It is not preferable because the mechanical strength of the monolith obtained after polymerizing the vinyl monomer is lowered, and the anion exchange capacity per unit volume is lowered. Monolithic intermediate total pore volumes in the specified range for B-type monolithic anion exchangers can be achieved using a monomer to water ratio of approximately 1:20 to 1:40.

In the monolithic intermediate, the average diameter of the openings (mesopores), which are the overlapping portions of macropores, is 5 to 100 μm in a dry state. If the average diameter of the openings is less than 5 μm in a dry state, the opening diameter of the monolith obtained after polymerizing the vinyl monomer will be small, and the pressure loss during fluid permeation will increase, which is not preferable. On the other hand, if it exceeds 100 μm, the opening diameter of the monolith obtained after polymerizing the vinyl monomer becomes too large, and the contact between the water to be treated and the monolith anion exchanger becomes insufficient, resulting in poor hydrogen peroxide decomposition properties. is not preferable because the The monolithic intermediate preferably has a uniform structure with uniform macropore sizes and opening diameters, but is not limited to this. It may be something to do.

The B-type monolith anion exchanger swells 1.4 to 1.9 times as much as the monolith, for example, because anion exchange groups are introduced into the monolith of co-continuous structure. Further, even if the pore diameter increases due to swelling, the total pore volume does not change. Therefore, the B-type monolithic anion exchanger has high mechanical strength because it has a skeleton, although the three-dimensionally continuous pore size is remarkably large. In addition, since the skeleton is thick, the anion exchange capacity per unit volume in a water-wet state can be increased, and the water to be treated can be passed for a long period of time at a low pressure and a large flow rate.

10 concentration analyzer 1 degassing device 2 hydrogen peroxide decomposition device 3a first concentration measuring device 3b second concentration measuring device 4 switching device 41 first on-off valve 42 second on-off valve 43 third on-off valve 44 Fourth on-off valve 5 Arithmetic device 11, 12 Flow rate adjusting means L1 Main pipe L10 Sampling pipe L11 First branch pipe L12 Second branch pipe L21 Connection pipe (first connection pipe)
L22 Second connecting pipe

Claims (8)

A concentration analyzer for analyzing the hydrogen peroxide concentration and dissolved oxygen concentration in sample water sampled from a predetermined position in a water treatment system,
a first pipe connected to the predetermined position and through which the sample water flows;
a second pipe connected to the predetermined position for circulating the sample water;
a degassing means provided in the first pipe for removing at least dissolved hydrogen in the sample water;
hydrogen peroxide decomposition means provided in the first pipe downstream of the degassing means for decomposing hydrogen peroxide in the sample water;
a third pipe connecting the first pipe between the degassing means and the hydrogen peroxide decomposition means and the second pipe;
a first concentration measuring means provided in the first pipe on the downstream side of the hydrogen peroxide decomposition means for measuring the concentration of dissolved oxygen in the sample water;
a second concentration measuring means provided in the second pipe on the downstream side of the joint between the second pipe and the third pipe for measuring the concentration of dissolved oxygen in the sample water;
calculating means for calculating the concentration of hydrogen peroxide in the sample water based on the result of measurement by the first concentration measuring means and the result of measurement by the second concentration measuring means ;
The first concentration measuring means measures the concentration of dissolved oxygen in the sample water that has flowed through the first supply route passing through the degassing means and the hydrogen peroxide decomposition means via the first pipe. It is designed to measure the concentration of 1,
The second concentration measuring means communicates from the third pipe to the second pipe through the first pipe, through the degassing means, and without passing through the hydrogen peroxide decomposition means. A second concentration that is the dissolved oxygen concentration of the sample water that has flowed through the second supply route, and a third concentration that does not pass through the degassing means and the hydrogen peroxide decomposition means via the second pipe. and a third concentration, which is the dissolved oxygen concentration of the sample water that has flowed through the supply route, are separately measured,
The computing means calculates the excess concentration in the sample water based on the difference between the first concentration value measured by the first concentration measuring means and the second concentration value measured by the second concentration measuring means. A concentration analyzer that calculates the concentration of hydrogen oxide . The sample water is circulated through the first supply route and the second supply route, the first concentration is measured by the first concentration measuring means, and the second concentration measuring means measures the a first measurement mode for measuring a second concentration; circulating the sample water through the first supply route and the third supply route; 2. The concentration analyzer according to claim 1, further comprising switching means for switching between a second measurement mode for measuring the concentration and measuring the third concentration by the second concentration measurement means. The switching means is provided in the second pipe on the upstream side from a connection portion between the first on-off valve provided in the third pipe and the second pipe and the third pipe. and a second on-off valve,
In the first measurement mode, the first on-off valve is opened and the second on-off valve is closed. In the second measurement mode, the first on-off valve is closed and the second 3. The concentration analyzer according to claim 2, wherein two on-off valves are opened. 4. The concentration analyzer according to claim 3, further comprising flow rate adjusting means provided in each of said first and second pipes for adjusting the flow rate of said sample water flowing through said pipes. downstream from the hydrogen peroxide decomposing means and upstream from the first concentration measuring means, and downstream from the connecting portion between the second pipe and the third pipe; further comprising a fourth pipe connecting the second pipe upstream of the second concentration measuring means and the second pipe;
the first concentration measuring means separately measures the first concentration and the third concentration ;
the second concentration measuring means separately measures the first concentration, the second concentration, and the third concentration ;
The switching means circulates the first measurement mode, the second measurement mode, and the sample water through the first supply path to supply the first concentration measurement means. At the same time that the first concentration is measured by the first concentration measuring means, the sample water that has flowed through the first supply route is passed from the fourth pipe through the second pipe to the second concentration measuring means. and the first concentration is measured by the second concentration measuring means, or the sample water is circulated through the third supply route and supplied to the second concentration measuring means Simultaneously with measuring the third concentration by the second concentration measuring means, the sample water that has flowed through the third supply route is supplied from the fourth pipe through the first pipe to the first pipe. configured to switch between a third measurement mode in which the first concentration measurement means is supplied with the first concentration measurement means and the third concentration is measured by the first concentration measurement means;
The calculating means corrects the difference based on the measurement results obtained by the first and second concentration measuring means in the third measurement mode, and calculates the concentration of hydrogen peroxide in the sample water from the corrected difference. 3. The concentration analyzer according to claim 2, which calculates . The switching means is provided in the second pipe on the upstream side from a connection portion between the first on-off valve provided in the third pipe and the second pipe and the third pipe. a second on-off valve, a third on-off valve provided in the fourth pipe , and a connection between the first pipe and the fourth pipe on the downstream side of the hydrogen peroxide decomposition means. and a fourth on-off valve provided in the first pipe on the upstream side of the part,
In the first measurement mode, the first and fourth on-off valves are opened and the second and third on-off valves are closed. In the second measurement mode, the first and third on-off valves are closed. The on-off valve is closed and the second and fourth on-off valves are opened. In the third measurement mode, the first and second on-off valves are closed and the third and fourth on-off valves are closed. 6. The concentration analyzer according to claim 5, wherein a valve is opened, or said first and fourth on-off valves are closed and said second and third on-off valves are opened. 7. The concentration analyzer according to claim 6, further comprising flow rate adjusting means provided in each of said first and second pipes for adjusting the flow rate of said sample water flowing through said pipes. 8. A concentration analyzer according to any one of claims 1 to 7, wherein said hydrogen peroxide decomposition means comprises a supported platinum group metal catalyst.

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