JP2006090732A - Method and instrument for measuring total organic carbon content - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an instrument for measuring a total organic carbon content capable of measuring precisely and easily a TOC value, even in a sample liquid containing a high content of electrolyte component and inorganic carbon other than an organic compound, and capable of reducing a size of the instrument. <P>SOLUTION: Gas in the sample liquid in a sample liquid flow passage LS inside a reactor 1 is absorbed into an absorbent liquid in an absorbent liquid flow passage LA via a gas permeable tube provided inside the reactor 1 to measure the first conductivity x<SB>1</SB>when the conductivity of the absorbent liquid reaches an equilibrium condition. Then, an ultraviolet light source 2 lights on to oxidize the organic compound in the sample liquid, and generated carbon dioxide is absorbed into the absorbent liquid via the gas permeable tube 3 to measure the second conductivity x<SB>2</SB>when the conductivity of the absorbent liquid reaches an equilibrium condition. The total organic carbon content in the sample liquid is found based on a difference between the second conductivity x<SB>2</SB>and the first conductivity x<SB>1</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for measuring the total organic carbon content in a sample liquid, and more particularly to a wet oxidation conductivity type total organic carbon suitable for measuring the total organic carbon content of a high conductivity sample liquid. The present invention relates to a content measuring method and apparatus.

One method of expressing the cleanliness of water is the total organic carbon content (hereinafter sometimes referred to as the TOC value) representing the degree of contamination by the amount of carbon contained in organic matter in water.
As a method for measuring such a TOC value, a method using ultraviolet (UV) oxidation is widely used. Specifically, by irradiating the sample liquid with ultraviolet rays, the organic compound in the sample liquid is oxidized to generate carbon dioxide, and the change in conductivity that occurs according to the change in the concentration of carbon dioxide is measured. The TOC value of the sample solution is obtained.

  Since this method is a method for measuring the content of the organic compound based on the change in conductivity, an error occurs if a large amount of components such as an electrolyte affecting the conductivity exists in the sample solution. Therefore, it is suitable when highly purified ultrapure water is used as a measurement target, but is sufficient when a sample containing a large amount of electrolyte components in addition to organic compounds such as clean water is used as a measurement target. There was a problem that a high accuracy could not be obtained.

Therefore, after oxidizing the ultraviolet rays in the reaction vessel to generate carbon dioxide, the generated carbon dioxide is absorbed into the deionized water through the gas permeable membrane on the downstream side of the reaction vessel, and then this deionized water It has been proposed to determine the total organic carbon content by measuring the electrical conductivity. In this case, the electrolyte coexisting in the sample solution does not permeate the gas permeable membrane and remains in the sample solution. Therefore, regardless of the electrolyte concentration in the sample solution, the corresponding carbon dioxide concentration is accurately obtained from the conductivity. (See Patent Document 1).
However, just using a gas permeable membrane on the downstream side of the reaction vessel, the inorganic carbon (carbon dioxide) that originally existed before UV oxidation and the electrolyte that can be gasified such as ammonia present in the sample solution. The effect cannot be excluded. For this reason, the apparatus of Patent Document 1 eliminates the influence of coexisting inorganic carbon, etc. by separately measuring the inorganic carbon content present in the sample solution or by performing pretreatment to remove inorganic carbon etc. in advance. ing.
Japanese National Publication No. 4-507141

However, in the apparatus of Patent Document 1, it is necessary to separately provide a module for transferring carbon dioxide to deionized water via a gas permeable membrane on the downstream side of the reaction vessel. It has become complicated.
Furthermore, in the apparatus of Patent Document 1, a system for separately measuring the content of inorganic carbon present in the sample solution and a pretreatment module for removing inorganic carbon and the like in advance are also necessary. Has been increasing in size and complexity.

  The present invention has been made in view of the above circumstances, and it is possible to accurately and easily measure the TOC value of a sample solution containing a large amount of an electrolyte component and inorganic carbon in addition to an organic compound, and downsizing the apparatus. It is an object of the present invention to provide a method and apparatus for measuring the total organic carbon content.

In order to solve the above problems, the present invention includes the following aspects.
[1] A method for measuring the total organic carbon content in a sample solution, in which the gas in the sample solution in the reactor is absorbed by the absorbing solution through a gas permeable membrane disposed in the reactor. A first measurement step for measuring the first conductivity, which is the conductivity of the absorbing solution after a sufficient time has elapsed for the conductivity of the solution to reach an equilibrium state, and after the first measurement step, After oxidizing the organic compound in the sample liquid, the generated carbon dioxide is absorbed into the absorption liquid through the gas permeable membrane, and after a sufficient time has elapsed for the conductivity of the absorption liquid to reach an equilibrium state. A second measurement step of measuring a second conductivity, which is the conductivity of the absorbent, and the second conductivity obtained in the second measurement step and the first conductivity obtained in the first measurement step A method for measuring the total organic carbon content, wherein the total organic carbon content in the sample solution is determined from the difference between the total organic carbon content and the sample liquid.

[2] A method for measuring the total organic carbon content in a sample solution, in which the gas in the sample solution in the reactor is absorbed by the absorbing solution through a gas permeable membrane disposed in the reactor. A first measurement step for measuring the first conductivity, which is the conductivity of the absorbing solution after a sufficient time has elapsed for the conductivity of the solution to reach an equilibrium state, and after the first measurement step, While oxidizing the organic compound in the sample liquid, the generated carbon dioxide is absorbed into the absorption liquid through the gas permeable membrane, and the second conductivity which is the conductivity of the absorption liquid after a predetermined time has elapsed. And measuring the total organic carbon content in the sample liquid from the difference between the second conductivity obtained in the second measurement step and the first conductivity obtained in the first measurement step. A method for measuring the total organic carbon content characterized in that it is obtained.
[3] The method for measuring the total organic carbon content according to [1] or [2], wherein the absorbing solution is deionized water.

[4] A method for measuring the total organic carbon content in a sample solution, wherein the absorbing solution absorbs the gas in the sample solution in the reactor through a gas permeable membrane disposed in the reactor, A first measurement step of measuring the base conductivity, which is the conductivity of the absorbing solution after sufficient time has passed for the absorbing solution to deionize and to reach the equilibrium state of the absorbing solution; After the process, while oxidizing the organic compound in the sample liquid in the reactor, the generated carbon dioxide is absorbed into the absorption liquid through the gas permeable membrane, and the conductivity of the absorption liquid reaches an equilibrium state. A second measurement step of measuring a second conductivity, which is the conductivity of the absorbing liquid after a sufficient time has elapsed, and a second conductivity obtained in the second measurement step, and a first measurement step The total organic carbon content in the sample solution is obtained from the difference from the base conductivity obtained in step 1. The measurement method of the machine carbon content.

[5] A method for measuring the total organic carbon content in a sample liquid, the gas in the sample liquid in the reactor being absorbed into the absorbing liquid through the gas permeable membrane disposed in the reactor, A first measurement step of measuring the base conductivity, which is the conductivity of the absorbing solution after sufficient time has passed for the absorbing solution to deionize and for the conductivity of the absorbing solution to reach an equilibrium state; After the process, while oxidizing the organic compound in the sample liquid in the reactor, the generated carbon dioxide is absorbed into the absorbing liquid through the gas permeable membrane, and the conductive property of the absorbing liquid after a predetermined time has passed. A second measurement step for measuring the second conductivity, which is a ratio, and a sample liquid from a difference between the second conductivity obtained in the second measurement step and the base conductivity obtained in the first measurement step A method for measuring the total organic carbon content, wherein the total organic carbon content is determined.
[6] The method for measuring the total organic carbon content according to any one of [1] to [5], wherein the organic compound in the sample solution is oxidized by ultraviolet irradiation in the second measurement step.

[7] A sample liquid flow separated from each other by the gas permeable membrane is provided with a reactor, a gas permeable membrane disposed in the reactor, a light source, and a conductivity sensor. A channel and an absorption liquid channel are formed, the sample solution flows into and out of the sample solution channel, a photocatalyst is disposed therein, and the light source emits light into the sample solution channel. The absorption liquid flows into and out of the absorption liquid flow path, and the conductivity sensor measures the absorption liquid flow so as to measure the conductivity of the absorption liquid. A total organic carbon content measuring device provided in the channel or downstream of the absorption liquid channel.

[8] The total organic carbon content measuring apparatus according to [7], wherein the light source is an ultraviolet light source that irradiates ultraviolet rays.
[9] The total organic carbon content measuring apparatus according to [7] or [8], further including a return flow path connecting the outlet and the inlet of the absorption liquid flow path.
[10] The total organic carbon content measuring apparatus according to [9], further including a deionization module that supplies deionized water to the return channel.

According to the present invention, since the gas permeable membrane is disposed in the reactor, it is possible to oxidize the organic compound in the reactor and transfer the carbon dioxide gas absorbing solution generated thereby. Moreover, transfer to the absorption liquid of inorganic components, such as an electrolyte component and inorganic carbon, can also be performed in a reactor. Therefore, it is not necessary to separately prepare a system for measuring the inorganic component present in the sample solution and a pretreatment module for removing the inorganic component in advance.
Therefore, according to the present invention, even a sample solution containing a large amount of an electrolyte component, inorganic carbon, etc. in addition to an organic compound, the TOC value can be measured accurately and easily, and the total organic size can be reduced. A carbon content measuring method and apparatus can be provided.

[Measurement device A]
FIG. 1 shows an embodiment of the total organic carbon content measuring apparatus according to the present invention. The measuring apparatus of the present embodiment includes a reactor 1, an ultraviolet light source 2 inserted into the reactor 1, a gas permeable tube 3 that spirals around the ultraviolet light source 2 in the reactor 1, and a gas permeable tube. A return flow path LB that connects between the inlet 3a and the outlet 3b of the conductive tube 3, a conductivity sensor EL and a pump P1 interposed in the return flow path LB, and a deionization module 10 that communicates with the return flow path LB. It is roughly composed.

The outside of the gas permeable tube 3 inside the reactor 1 is a sample liquid flow path LS. The inside of the gas permeable tube 3 is an absorption liquid flow path LA.
A pump P2 and an opening / closing valve SV1 are interposed in the flow path L1 connecting the sample inlet and the inlet 1a of the reactor 1. A check valve 5 is interposed in the flow path L2 connecting the outlet 1b of the reactor 1 and the sample outlet. A converter 4 is connected to the conductivity sensor EL.

The gas permeable tube 3 is formed of a gas permeable membrane that allows gas to pass but does not allow liquid to pass. The gas permeable film is preferably an ultraviolet permeable film. By making it ultraviolet permeable, since the ultraviolet rays from the ultraviolet light source 2 can reach the sample liquid existing outside the gas permeable tube 3, the oxidation efficiency is improved. Moreover, it is preferable that it is a material excellent in ultraviolet-ray resistance so that it may not deteriorate with an ultraviolet-ray. An example of such a material is an optical fluororesin.
In addition, if the ultraviolet rays do not reach the gas permeable tube 3, it is possible to use a material having insufficient ultraviolet resistance. For example, if the gas permeable tube 3 is covered with a photocatalyst, a structure having pores such as a sponge, or a bead of glass or the like with a photocatalyst coated, a material having insufficient UV resistance is obtained. The gas permeable tube 3 can be used.

A mercury lamp is preferably used as the ultraviolet light source 2, but is not particularly limited to this, and a xenon flash lamp, an ultraviolet lamp using silent discharge, or the like can also be used.
In addition, a photocatalyst for promoting ultraviolet oxidation is disposed in the sample solution flow path LS in the reactor 1. As the photocatalyst, titanium oxide (TiO ₂ ) can be most preferably used, but as others, SrTiO ₃ , CDS, WO ₃ , Fe ₂ O ₃ , MO _{3 and the} like can be mentioned.
In order to arrange the photocatalyst in the sample liquid flow path LS, the photocatalyst may be filled in the sample liquid flow path LS, or the inner wall of the reactor 1 or glass, plastic filled in the sample liquid flow path LS, You may coat on the structure which has holes, such as beads, small pieces, or balls, or sponges, such as ceramics, or a flexible metal net, mesh, etc.
As a means for coating the photocatalyst, a mechanical method or a chemical method may be used.

The deionization module 10 includes a tank 11, an ultrafilter 12, an ion exchanger 13, and a three-way valve SV2. The deionization module 10 can remove various components including carbonate ions generated by dissolving carbon dioxide by combining the ion filter 13 with the ultrafilter 12. Therefore, it is possible to supply good zero water whose conductivity is converted to a TOC value and is 1 ppb or less.
A check valve 14 is interposed in the flow path L3 that connects the upstream side of the return flow path LB and the tank 11. A pump P3 is interposed in the flow path L4 that connects between the tank 11 and the ultrafilter 12. The previous ion exchanger 13 is interposed in the flow path L5 connecting between the ultrafilter 12 and the three-way valve SV2. A check valve 15 is interposed in the flow path L6 that connects the three-way valve SV2 and the downstream side of the return flow path LB.
Further, between the ultrafilter 12 and the tank 11, a flow path L7 for returning the absorbing liquid that cannot pass through the ultrafilter 12 to the tank 11 is between the three-way valve SV2 and the flow path L7. Are each provided with a flow path L8 for returning the absorbing liquid to the tank 11 when communication between the deionization module 10 and the return flow path LB is cut off.

  The measurement of the total organic carbon content by the measuring apparatus of this embodiment can be performed by any one of the following measuring methods A to C.

[Measurement method A]
As the measurement method A, first, the old sample solution in the sample solution channel LS is replaced with a new sample solution, and the absorption solution in the absorption solution channel LA is changed to a sufficiently purified absorption solution (deionized water). Replace (preparation step).
Next, the gas in the sample liquid is absorbed by the absorption liquid through the gas permeable tube 3 without irradiating the ultraviolet light from the ultraviolet light source 2, and the conductivity of the absorption liquid is sufficient to reach an equilibrium state. The electrical conductivity (first electrical conductivity) of the absorbent after the elapse of time is measured (first measurement step).
Next, while irradiating the sample liquid with ultraviolet light from the ultraviolet light source 2, carbon dioxide generated in the sample liquid is absorbed into the absorption liquid through the gas permeable tube 3, and the conductivity of the absorption liquid is in an equilibrium state. The electrical conductivity (second electrical conductivity) of the absorbing solution after a sufficient time has passed to reach the value (second measurement step).
Then, the total organic carbon content in the sample solution is obtained from the difference between the second conductivity obtained in the second measurement step and the first conductivity obtained in the first measurement step (calculation).
Hereinafter, each process is explained in full detail.

(Preparation process)
The opening / closing valve SV1 is opened and the pump P2 is operated to cause the sample liquid to flow through the sample liquid flow path LS. Further, the pump P1 is operated to circulate the absorption liquid in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB.
On the other hand, the NO port side of the three-way valve SV2 is opened to operate the pump P3. Thereby, the absorption liquid supplied from the tank 11 and purified by passing through the ultrafilter 12 and the ion exchanger 13 is supplied to the return flow path LB via the flow path L6. And after joining with the absorption liquid in the circulation flow path which consists of the said absorption liquid flow path LA and the return flow path LB, it returns to the tank 11 via the flow path L3.
As a result, the absorption liquid in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB is gradually replaced with the absorption liquid purified by the ultrafilter 12 and the ion exchanger 13. Let x ₀ (base conductivity) be the output value of the conductivity sensor EL when the absorbing solution in the circulation channel is sufficiently replaced with the purified absorbing solution.

By performing the preparatory step, the base conductivity x ₀ is improved decreases measurement accuracy. However, the preparation process is not essential. When the preparation step is not performed, an output value x ₁ (first conductivity) obtained in the first measurement step described later and an output value x ₂ (second conductivity) obtained in the second measurement step are increased. This is because the difference Δx ₂ (x ₂ −x ₁ ) between the two is theoretically not affected.

(First measurement process)
Next, the opening / closing valve SV1 is closed and the pump P2 is stopped. At the same time, the NO port side of the three-way valve SV2 is closed and the NC port side is opened, thereby disconnecting the deionization module 10 from the return flow path LB. Note that the operation of the pump P1 is not stopped and the circulation in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB is continued. Further, the operation of the pump P3 is not stopped and the purification of the absorbent is continued.
During this time, the gas originally present in the sample liquid flow path LS passes through the gas permeable tube 3 and moves to the absorption liquid flow path LA. The gas transition is continued until the gas concentration of the absorption liquid in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB becomes equal to the gas concentration of the sample liquid in the sample liquid flow path LS.
When the gas concentration of the absorption liquid in the circulation flow path becomes equal to the gas concentration in the sample liquid flow path LS, the output value of the conductivity sensor EL reaches equilibrium. The output value at this time is defined as x ₁ (first conductivity).

(Second measurement process)
Next, the ultraviolet light source 2 is turned on with the valve open / closed state and pump operating state being the same as in the first measurement step. Thereby, the organic compound in the sample liquid flow path LS is oxidized and carbon dioxide gas is generated.
The generated carbon dioxide gas passes through the gas permeable tube 3 and moves to the absorption liquid channel LA. In the transfer of carbon dioxide gas, the carbon dioxide gas concentration of the absorption liquid in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB is equal to the carbon dioxide gas concentration of the sample liquid in the sample liquid flow path LS. Continue until
When the carbon dioxide gas concentration of the absorbing liquid in the circulation channel becomes equal to the carbon dioxide gas concentration in the sample solution channel LS, the output value of the conductivity sensor EL reaches equilibrium. The output value at this time is assumed to be x ₂ (second conductivity).

(Calculation)
The first conductivity x ₁ in the first measurement step and the second conductivity x _{2 in} the second measurement step are each output to the arithmetic device (not shown) via the converter 4. In the arithmetic unit, the total organic carbon content is calculated from the difference Δx ₂ between the second conductivity x ₂ and the first conductivity x ₁ .
The timing of capturing the first conductivity x ₁ and the data of the second conductivity x ₂ to the arithmetic unit may be a case where the conductivity from the output value of the conductivity sensor EL was confirmed that equilibrium was reached It is also possible to determine a certain time during which sufficient equilibrium can be reached and when that time has elapsed.
It will be described with reference to FIG. 2 that the total organic carbon content thus determined is not affected by the inorganic component.

The change in the output value of conductivity in the first measurement process and the second measurement process is as shown in FIG. The difference Δx ₁ between the first conductivity x ₁ obtained in the first measurement step and the base conductivity x ₀ obtained in the preparation step is such as carbon dioxide gas or ammonia gas originally present in the sample liquid, Proportional to the concentration of inorganic components. Further, the difference Δx ₂ between the second conductivity x ₂ obtained in the second measurement step and the first conductivity x ₁ obtained in the first measurement step is a carbon dioxide gas generated in the sample liquid by ultraviolet oxidation. Proportional to concentration. That is, it is proportional to the total organic carbon content of the sample solution. That is, the total organic carbon content can be obtained from Δx ₂ without being affected by the inorganic component.
After calculating | requiring the total organic carbon content by the above, the total organic carbon content of a sample liquid can be measured intermittently by repeating the process from a preparation process again.

FIG. 3 shows the measurement method A when the concentration of inorganic components such as carbon dioxide gas and ammonia gas originally present in the sample solution is high and the total organic carbon content of the sample solution is low. Is a change in the output value of conductivity obtained by
In this case, as shown in FIG. 3, the difference Δx ₁ between the first conductivity x ₁ obtained in the first measurement process and the base conductivity x ₀ obtained in the preparation process becomes large. On the other hand, the difference Δx ₂ between the second conductivity x ₂ obtained in the second measurement step and the first conductivity x ₁ obtained in the first measurement step is a relatively small value.
Therefore, it becomes difficult to obtain the value of [Delta] x ₂ exactly, hence, it becomes difficult or accurately determine that the value of total organic carbon content without being affected by the inorganic component.
In such a case, it is preferable to measure by the measuring method B described below.

[Measurement method B]
As the measurement method B, first, the old sample solution in the sample solution channel LS is replaced with a new sample solution, and the absorption solution in the absorption solution channel LA is changed to a sufficiently purified absorption solution (deionized water). Replace (preparation step).
Next, in a state where the ultraviolet light from the ultraviolet light source 2 is not irradiated, the absorption liquid is deionized while absorbing the gas in the sample liquid into the absorption liquid through the gas permeable tube 3, and the conductivity of the absorption liquid is determined. Measure the conductivity (base conductivity) of the absorbing solution after a sufficient time has passed to reach an equilibrium state (first measurement step).
Next, while irradiating the sample liquid with ultraviolet light from the ultraviolet light source 2, carbon dioxide generated in the sample liquid is absorbed into the absorption liquid through the gas permeable tube 3, and the conductivity of the absorption liquid is in an equilibrium state. The electrical conductivity (second electrical conductivity) of the absorbing solution after a sufficient time has passed to reach the value (second measurement step).
Then, the total organic carbon content in the sample solution is obtained from the difference between the second conductivity obtained in the second measurement step and the base conductivity obtained in the first measurement step (calculation).
Hereinafter, each process is explained in full detail.

(Preparation process)
The opening / closing valve SV1 is opened and the pump P2 is operated to cause the sample liquid to flow through the sample liquid flow path LS. Further, the pump P1 is operated to circulate the absorption liquid in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB.
On the other hand, the NO port side of the three-way valve SV2 is opened to operate the pump P3. Thereby, the absorption liquid supplied from the tank 11 and purified by passing through the ultrafilter 12 and the ion exchanger 13 is supplied to the return flow path LB via the flow path L6. And after joining with the absorption liquid in the circulation flow path which consists of the said absorption liquid flow path LA and the return flow path LB, it returns to the tank 11 via the flow path L3.
As a result, the absorption liquid in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB is gradually replaced with the absorption liquid purified by the ultrafilter 12 and the ion exchanger 13. Let x ₀ (base conductivity) be the output value of the conductivity sensor EL when the absorbing solution in the circulation channel is sufficiently replaced with the purified absorbing solution.

By performing a preparatory process, the below-mentioned 1st measurement process can be completed in a short time. However, the preparation process is not essential. Even without preparation step, taking sufficient time in the first measuring step described below, because the base conductivity x ₀ is obtained.

(First measurement process)
Next, the opening / closing valve SV1 is closed and the pump P2 is stopped. The three-way valve SV2 keeps the NO port side open, and the pumps P1 and P3 continue to operate.
During this time, the gas originally present in the sample liquid flow path LS passes through the gas permeable tube 3 and moves to the absorption liquid flow path LA, so that the output value of the conductivity sensor EL temporarily rises.
Since the transferred gas is removed by the ultrafilter 12 and the ion exchanger 13, the gas transfer is continued until almost the entire amount of the gas in the sample liquid flow path LS is transferred to the absorption liquid flow path LA. Migration of the gas is finished, the absorbing liquid in the circulation flow path is sufficiently replaced with the absorption liquid that has been purified, the output value of the conductivity sensor EL is returned to the base conductivity x ₀ again.

(Second measurement process)
Next, the NO port side of the three-way valve SV2 is closed and the NC port side is opened, and the communication between the deionization module 10 and the return flow path LB is shut off. Note that the operation of the pump P1 is not stopped and the circulation in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB is continued. Further, the operation of the pump P3 is not stopped and the purification of the absorbent is continued.
Then, the ultraviolet light source 2 is turned on. Thereby, the organic compound in the sample liquid flow path LS is oxidized and carbon dioxide gas is generated.
The generated carbon dioxide gas passes through the gas permeable tube 3 and moves to the absorption liquid channel LA. In the transfer of carbon dioxide gas, the carbon dioxide gas concentration of the absorption liquid in the circulation flow path composed of the absorption liquid flow path LA and the return flow path LB is equal to the carbon dioxide gas concentration of the sample liquid in the sample liquid flow path LS. Continue until
When the carbon dioxide gas concentration of the absorbing liquid in the circulation channel becomes equal to the carbon dioxide gas concentration in the sample solution channel LS, the output value of the conductivity sensor EL reaches equilibrium. The output value at this time is assumed to be x ₂ (second conductivity).

(Calculation)
And outputs to each (not shown) through the transducer 4 computing device based conductivity x ₀ and a second conductivity x ₂ in the second step of measuring the first measurement step. In the arithmetic unit, the total organic carbon content is calculated from the difference Δx ₂ between the second conductivity x ₂ and the base conductivity x ₀ .
Note that the timing at which the data of the base conductivity x ₀ and the second conductivity x ₂ is taken into the arithmetic unit may be when the conductivity has reached equilibrium from the output value of the conductivity sensor EL, It is also possible to determine a certain time during which the equilibrium is sufficiently reached and when that time has elapsed.
It will be described with reference to FIG. 4 that the total organic carbon content thus obtained is not affected by the inorganic component.

The change in the output value of conductivity in the first measurement process and the second measurement process is as shown in FIG. In the first measurement step, if the connection between the deionization module 10 and the return flow path LB is interrupted, the first conductivity x ₁ that would have been obtained and the base conductivity obtained in the first measurement step. The difference Δx _{1 from} x ₀ is proportional to the concentration of inorganic components such as carbon dioxide gas and ammonia gas originally present in the sample liquid. This inorganic component is removed from the sample solution and the absorbing solution at the end of the first step.
Therefore, the difference Δx ₂ between the second conductivity x ₂ obtained in the second measurement step and the base conductivity x ₀ obtained in the first measurement step is the concentration of carbon dioxide gas generated in the sample liquid by ultraviolet oxidation. Is proportional to That is, it is proportional to the total organic carbon content of the sample solution. That is, the total organic carbon content can be obtained from Δx ₂ without being affected by the inorganic component.
After calculating | requiring the total organic carbon content by the above, the total organic carbon content of a sample liquid can be measured intermittently by repeating the process from a preparation process again.

[Measurement method C]
Measurement Method C, except that the timing to capture data of the second conductivity x ₂ in the operation unit is different is the same as the measuring method A. In the measurement method C, determine the short predetermined time than the conductivity of the absorption liquid may reach a sufficiently balanced, when the predetermined time has elapsed, take in the data of the second conductivity x ₂ in the arithmetic unit.
In this case, the difference Δx ₂ between the second conductivity x ₂ obtained in the second measurement step and the first conductivity x ₁ obtained in the first measurement step is equal to or less than that in the measurement method A. However, by taking in the data for a predetermined time (fixed time), it becomes a value proportional to the total organic carbon content.
Therefore, although the accuracy is somewhat lower than that of the measuring method A, it is possible to quickly measure the total organic carbon content.

[Measurement device B]
FIG. 5 shows another embodiment of the total organic carbon content measuring apparatus according to the present invention. In FIG. 5, the same reference numerals as those in FIG. 1 are assigned to the same components as those of the measuring apparatus A in FIG. 1, and the detailed description thereof is omitted.
The measuring apparatus of this embodiment includes a reactor 1, an ultraviolet light source 2 disposed outside the reactor 1, a plurality of gas permeable tubes 3 disposed linearly in the reactor 1, and a plurality of gas permeable properties. A return flow path LB that connects between the inlet 3a and the outlet 3b in which the tubes 3 are combined, a conductivity sensor EL and a pump P1 interposed in the return flow path LB, and a deionization module 10 that communicates with the return flow path LB. It is roughly composed of

As shown in FIG. 6, the outside of the gas permeable tubes 3 inside the reactor 1 is a sample solution flow path LS. The inside of each gas permeable tube 3 is an absorption liquid flow path LA.
The sample solution flow path LS in the reactor 1 is filled with beads 20 coated with a photocatalyst for promoting ultraviolet oxidation.

Similarly to the measuring apparatus A, a pump P2 and an open / close valve SV1 are interposed in the flow path L1 that connects the sample inlet and the inlet 1a of the reactor 1. A check valve 5 is interposed in the flow path L2 connecting the outlet 1b of the reactor 1 and the sample outlet. A converter 4 is connected to the conductivity sensor EL. The configuration of the deionization module 10 is the same as that of the measuring apparatus A.
In the measurement apparatus of this embodiment, since the ultraviolet light source 2 is disposed outside the reactor 1, the reactor 1 is preferably made of an ultraviolet light transmissive material, for example, quartz glass. Further, in the measuring apparatus of the present embodiment, the gas permeable tube 3 is filled with the beads 20 coated with the photocatalyst, so that the ultraviolet rays hardly reach the gas permeable tube 3. Therefore, as the material of the gas permeable tube 3, a material having insufficient UV resistance can be used.
The measurement of the total organic carbon content by the measuring apparatus of this embodiment can also be performed by any one of the above measuring methods A to C.

[Measurement device C]
FIG. 7 shows another embodiment of the total organic carbon content measuring apparatus according to the present invention. In FIG. 7, the same reference numerals as those in FIG. 1 are assigned to the same components as those of the measuring apparatus A in FIG. 1, and detailed descriptions thereof are omitted.
The measurement apparatus of this embodiment does not have the return flow path LB and the deionization module 10, the conductivity sensor EL is downstream of the outlet 3 b of the gas permeable tube 3, and the pump P 1 is the inlet 3 a of the gas permeable tube 3. The measuring apparatus A is the same as the measuring apparatus A except that it is arranged on the upstream side.

  The measurement of the total organic carbon content by the measuring apparatus of this embodiment can be performed by the following measuring method D.

[Measurement method D]
As the measurement method D, first, the old sample solution in the sample solution channel LS is replaced with a new sample solution, and the absorption solution in the absorption solution channel LA is changed to a sufficiently purified absorption solution (deionized water). Replace (preparation step).
Next, the absorption liquid is replaced with deionized water while absorbing the gas in the sample liquid into the absorption liquid through the gas permeable tube 3 without irradiating the ultraviolet light from the ultraviolet light source 2. The conductivity (base conductivity) of the absorbing solution after a sufficient time has elapsed for the conductivity to reach an equilibrium state (first measurement step).
Next, while irradiating the sample liquid with ultraviolet rays from the ultraviolet light source 2, carbon dioxide generated in the sample liquid is absorbed by the absorption liquid through the gas permeable tube 3, and absorption after a predetermined time has elapsed. The conductivity (second conductivity) of the liquid is measured (second measurement step).
Then, the total organic carbon content in the sample solution is obtained from the difference between the second conductivity obtained in the second measurement step and the base conductivity obtained in the first measurement step (calculation).
Hereinafter, each process is explained in full detail.

(Preparation process)
The opening / closing valve SV1 is opened and the pump P2 is operated to cause the sample liquid to flow through the sample liquid flow path LS.

(First measurement process)
Next, the opening / closing valve SV1 is closed and the pump P2 is stopped. On the other hand, the pump P1 is operated, deionized water is supplied from the absorption liquid inlet, and is circulated in the absorption liquid flow path LA.
During this time, the gas originally present in the sample liquid flow path LS passes through the gas permeable tube 3 and moves to the absorption liquid flow path LA, so that the output value of the conductivity sensor EL temporarily rises.
Since deionized water continues to be supplied to the absorption liquid channel LA, the gas transfer continues until almost the entire amount of the gas in the sample liquid channel LS moves to the absorption liquid channel LA. When the gas transfer is completed and the absorption liquid in the absorption liquid flow path LA is sufficiently replaced with deionized water, the output value of the conductivity sensor EL is the base conductivity x ₀ which is the conductivity of the deionized water. It becomes.

(Second measurement process)
Next, the pump P1 is stopped and the ultraviolet light source 2 is turned on. Note that the on-off valve SV1 remains closed and the pump P2 remains stopped.
Thereby, the organic compound in the sample liquid flow path LS is oxidized and carbon dioxide gas is generated. The generated carbon dioxide gas passes through the gas permeable tube 3 and moves to the absorption liquid channel LA.
Then, after a predetermined time has elapsed after the ultraviolet light source 2 is turned on, the pump P2 is operated to send the absorption liquid in the absorption liquid flow path LA to the conductivity sensor EL. The output value at this time is assumed to be x ₂ (second conductivity).

(Calculation)
And outputs to each (not shown) via a converter 4 operation unit based conductivity x ₀ and a second conductivity x ₂ in the second step of measuring the first measurement step. In the arithmetic unit, the total organic carbon content is calculated from the difference Δx ₂ between the second conductivity x ₂ and the base conductivity x ₀ .
The timing for taking the data of the base conductivity x ₀ to the processing unit may be a case where the conductivity from the output value of the conductivity sensor EL was confirmed that equilibrium was reached, it can reach a sufficiently balanced constant It is also possible to decide when the time has elapsed and when that time has passed.
In the measuring method D, the second conductivity is determined by the length of time (predetermined time) from when the operation of the pump P1 is resumed after the ultraviolet light source 2 is turned on to when the absorption liquid in the absorption liquid flow path LA is sent to the conductivity sensor EL. the value of x ₂ is different. However, the difference between the predetermined time (predetermined time) by carrying out the transition to the absorption liquid flow path LA of carbon dioxide gas generated by this and oxidation by ultraviolet light source 2, a second conductivity x ₂ and the base conductivity x ₀ Δx ₂ is a value proportional to the total organic carbon content.

[Other forms of measuring device]
In the present invention, the specific form of the gas permeable membrane is not limited. In addition to the spiral tube of the measuring device A and the plurality of linear tubes of the measuring device B, for example, a flat membrane-like gas permeable membrane can be used although the gas permeation efficiency is lowered.
Further, the number and form of the ultraviolet light sources 2 are not limited. For example, in the measuring apparatus B, a plurality of ultraviolet light sources 2 may be arranged around the reactor 1.
Moreover, there is no limitation also in the shape of a reactor, and it can also be set as a spiral shape other than cylindrical shape like measuring apparatus AC. When the reactor is spiral, it is preferable to arrange the reactor so as to go around the ultraviolet light source 2. In this case, it is preferable to insert one or more tube-shaped membranes as the gas permeable membrane.
The specific configuration of the deionization module 10 is not particularly limited as long as it can deionize the absorption liquid in the circulation flow path including the absorption liquid flow path LA and the return flow path LB.

It is a schematic block diagram of the measuring apparatus A which concerns on one Embodiment of this invention. It is a graph which shows the output value change of the electrical conductivity in the 1st measurement process of the measuring method A, and a 2nd measurement process. It is a graph which shows the output value change of the electrical conductivity in the 1st measurement process of the measuring method A, and a 2nd measurement process. It is a graph which shows the output value change of the electrical conductivity in the 1st measurement process of measurement method B, and the 2nd measurement process. It is a schematic block diagram of the measuring apparatus B which concerns on other embodiment of this invention. It is a reactor of the measuring apparatus B, and its internal block diagram. It is a schematic block diagram of the measuring apparatus C which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Ultraviolet light source, 3 ... Gas-permeable tube, 4 ... Converter,
5, 14, 15 ... check valve, 10 ... deionization module,
11 ... Tank, 12 ... Ultrafilter, 13 ... Ion exchanger,
20 ... Beads LS ... Sample liquid flow path, LA ... Absorption liquid flow path, LB ... Return flow path,
L1-L8 ... flow path, EL ... conductivity sensor,
P1 to P3 ... pump, SV1 ... on-off valve, SV2 ... three-way valve,

Claims (10)

A method for measuring the total organic carbon content in a sample solution,
After the gas in the sample liquid in the reactor is absorbed by the absorption liquid through the gas permeable membrane disposed in the reactor, after a sufficient time has elapsed for the conductivity of the absorption liquid to reach an equilibrium state A first measurement step of measuring a first conductivity which is the conductivity of the absorbing liquid;
After the first measurement step, the generated carbon dioxide is absorbed into the absorbing solution through the gas permeable membrane while oxidizing the organic compound in the sample solution in the reactor, and the conductivity of the absorbing solution is in an equilibrium state. A second measurement step of measuring a second conductivity which is the conductivity of the absorbing liquid after a sufficient time has elapsed to reach
The total organic carbon content in the sample liquid is obtained from the difference between the second conductivity obtained in the second measurement step and the first conductivity obtained in the first measurement step. Measuring method. A method for measuring the total organic carbon content in a sample solution,
After the gas in the sample liquid in the reactor is absorbed by the absorption liquid through the gas permeable membrane disposed in the reactor, after a sufficient time has elapsed for the conductivity of the absorption liquid to reach an equilibrium state A first measurement step of measuring a first conductivity which is the conductivity of the absorbing liquid;
After the first measurement step, the generated carbon dioxide is absorbed into the absorption liquid through the gas permeable membrane while oxidizing the organic compound in the sample liquid in the reactor, and absorption after a predetermined time has elapsed. A second measurement step of measuring a second conductivity which is the conductivity of the liquid,
The total organic carbon content in the sample liquid is obtained from the difference between the second conductivity obtained in the second measurement step and the first conductivity obtained in the first measurement step. Measuring method.   The method for measuring the total organic carbon content according to claim 1 or 2, wherein the absorbing liquid is deionized water. A method for measuring the total organic carbon content in a sample solution,
While absorbing the gas in the sample liquid in the reactor into the absorbing liquid through the gas permeable membrane placed in the reactor, the absorbing liquid is deionized and the conductivity of the absorbing liquid reaches an equilibrium state. A first measurement step of measuring a base conductivity which is the conductivity of the absorbing liquid after a sufficient time has passed,
After the first measurement step, the generated carbon dioxide is absorbed into the absorbing solution through the gas permeable membrane while oxidizing the organic compound in the sample solution in the reactor, and the conductivity of the absorbing solution is in an equilibrium state. A second measurement step of measuring a second conductivity which is the conductivity of the absorbing liquid after a sufficient time has elapsed to reach
Measuring the total organic carbon content in the sample liquid from the difference between the second conductivity obtained in the second measurement step and the base conductivity obtained in the first measurement step Method. A method for measuring the total organic carbon content in a sample solution,
While absorbing the gas in the sample liquid in the reactor into the absorption liquid through the gas permeable membrane placed in the reactor, this absorption liquid is deionized, and the conductivity of the absorption liquid reaches an equilibrium state. A first measurement step of measuring a base conductivity which is the conductivity of the absorbing liquid after a sufficient time has passed,
After the first measurement step, the generated carbon dioxide is absorbed into the absorption liquid through the gas permeable membrane while oxidizing the organic compound in the sample liquid in the reactor, and absorption after a predetermined time has elapsed. A second measuring step of measuring a second conductivity which is the conductivity of the liquid,
Measuring the total organic carbon content in the sample liquid from the difference between the second conductivity obtained in the second measurement step and the base conductivity obtained in the first measurement step Method.   The method for measuring the total organic carbon content according to any one of claims 1 to 5, wherein in the second measurement step, the organic compound in the sample solution is oxidized by ultraviolet irradiation. A reactor, a gas permeable membrane disposed in the reactor, a light source, and a conductivity sensor;
In the reactor, a sample liquid channel and an absorption liquid channel separated from each other by the gas permeable membrane are formed,
In the sample liquid channel, the sample liquid flows in and out, and a photocatalyst is arranged inside,
The light source is arranged to irradiate light to the sample liquid channel,
In the absorption liquid channel, the absorption liquid flows in and out,
The total organic carbon content measuring apparatus, wherein the conductivity sensor is provided in the absorption liquid channel or downstream of the absorption liquid channel so as to measure the conductivity of the absorption liquid.   The total organic carbon content measuring apparatus according to claim 7, wherein the light source is an ultraviolet light source that emits ultraviolet light.   Furthermore, the total organic carbon content measuring apparatus of Claim 7 or Claim 8 provided with the return flow path which connects the exit and inlet of an absorption liquid flow path. The total organic carbon content measuring apparatus of Claim 9 provided with the deionization module which supplies deionized water to a return flow path.

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