TWI651534B - Chemical oxygen demand (COD) automatic measuring device - Google Patents

Abstract

The invention provides a chemical oxygen demand (COD) automatic measuring device, which has the advantages that even if the amount of the test liquid is small, the measurement can be performed with high accuracy, and the environmental load, the running cost, the recovered waste liquid and the supplementary reagent can be satisfied. Maintenance frequency, or reduced power consumption requirements. A COD automatic measuring device in which an upper surface of a reaction vessel has an opening, and a sample measuring portion and a bottom tubular sample heating portion that communicates with a bottom portion of the sample measuring portion and extends downward are formed. The area of the horizontal section of the sample heating portion is smaller than the area of the horizontal section of the sample measuring portion. Further, the volume of the sample heating portion is larger than the volume of the test solution during the oxidation reaction and smaller than the volume of the test solution to which the auxiliary liquid is added, the liquid surface position of the oxidation reaction step is located in the sample heating portion, and the liquid surface position of the titration step is located on the detection surface of the electrode. Upper part.

Description

Chemical oxygen demand (COD) automatic measuring device

The present invention relates to a chemical oxygen demand (COD) automatic measuring device capable of automatically determining the chemical oxygen demand (COD) of a test solution.

The chemical oxygen demand (COD) is one of the indexes of water pollution, and shows the amount of the oxidizing agent consumed when the oxidizable substance such as an organic compound contained in the test solution is oxidized by the oxidizing agent as the oxygen equivalent.

The measurement of COD can be carried out by a method as specified in JIS K 0102. In JIS K 0102, the method of "the oxygen demand (COD _Mn ) of potassium permanganate at 100 ° C", the test solution is made acidic with sulfuric acid, potassium permanganate is added as an oxidizing agent, and heated in a boiling water bath for 30 minutes. After the oxidation reaction is carried out, and an excessive amount of sodium oxalate is added to stop the oxidation, the test solution is kept at 50 ° C to 60 ° C, and then titrated with potassium permanganate to determine the amount of the oxidant consumed, thereby determining The COD of the test solution.

In the COD automatic measuring device, a double platinum electrode is used as a method for detecting the end point of the titration, and the constant current stepping potential difference method, and the platinum electrode and the reference electrode are used to measure the COD of the river water, the lake water, and the factory drainage. Oxidation reduction potential difference method. Further, in these automatic COD measuring apparatuses, the detection from the oxidation to the end point of the titration was carried out in one reaction tank. Therefore, the reaction tank has a cylindrical or conical shape having a wide opening in the upper portion (as disclosed in Patent Documents 1, 2) for The electrode (detector) for detecting the end point of the titration is inserted.

Prior art literature:

Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2005-195412

Patent Document 2: Japanese Patent Laid-Open Publication No. 2012-112733

Non-patent literature

Non-Patent Document 1: JIS K 0102:2013 "Factory Drainage Test Method"

Since the COD automatic measuring device has the above-described reagents, the amount of the reagent should be reduced from the viewpoints of reducing the environmental load, the running cost, the frequency of maintenance of the waste liquid and the replenishing reagent, and the like. In addition, the power required to measure the device should be reduced. By reducing the amount of test solution, the above problems can be effectively solved.

However, as described above, a cylindrical or conical reaction tank having a wide opening is formed in the upper portion of the reaction tank, and when the test liquid is heated, the amount of water evaporation is large. In the case where the amount of the test solution is small, the influence of the evaporation of water on the measured value cannot be ignored. Therefore, the prior art has a problem that measurement cannot be performed with high accuracy.

Further, the surface area of the liquid surface is reduced, and the amount of water evaporation can be effectively reduced. However, if the reaction tank is narrowed, there is a problem that a sufficient space cannot be secured for the electrode (detector) to be inserted.

The present invention has been made in view of the above problems, and an object thereof is to provide an automatic COD measuring device capable of accurately accurately even if the amount of the test liquid is small. By performing the measurement, it is also possible to satisfy the requirements of reducing the environmental load, the running cost, the frequency of maintenance such as the recovery of the waste liquid and the replenishing reagent, or reducing the power consumption.

In order to solve the above problems, the present invention adopts the following constitution.

According to a first aspect of the present invention, in an automatic COD measuring apparatus, an oxidizing agent is added to a predetermined amount of a test solution stored in a reaction tank, and is heated to perform an oxidation reaction for a predetermined period of time, and then the oxidation reaction is performed by titration. The amount of oxidant consumed, thereby determining the COD of the test solution, the device comprising: an auxiliary liquid introduction device that measures a certain amount of auxiliary to be added to the test solution after the oxidation reaction and before titration The auxiliary liquid is introduced into the reaction tank, and the reaction tank has a sample measuring unit and a sample heating unit, and the sample measuring unit has an opening formed on the upper surface, and the sample heating unit It has a bottomed tubular shape and communicates with the bottom of the sample measuring portion and extends downward.

The area of the horizontal section of the sample heating portion is smaller than the area of the horizontal section of the sample measuring portion, the volume of the sample heating portion is larger than the volume of the test solution at the time of the oxidation reaction, and the volume of the sample heating portion is smaller than The volume of the test solution after the addition of the auxiliary liquid.

According to a second aspect of the present invention, in the COD automatic measuring apparatus, the electrode for detecting an end point of the titration is provided, and the electrode is inserted into the sample measuring unit from the opening.

According to a third aspect of the present invention, in an automatic COD measuring device, an oxidizing agent is added to a test solution and heated to perform an oxidation reaction, and then the titration is performed to determine the amount of the oxidizing agent consumed during the oxidation reaction. Measuring the COD of the test solution, comprising: a reaction tank having a sample measurement unit and a sample heating unit, the sample measurement unit having an opening formed on the upper surface, the sample heating portion having a bottomed tube shape Connected to the bottom of the sample measuring unit and extending downward; the area of the horizontal section of the sample heating unit is smaller than the area of the horizontal section of the sample measuring unit, and the electrode is used for detecting insertion from the opening into the The end point of the titration of the sample measuring unit; and a control unit that can control the entire device; the control unit sequentially performs the following steps: (1) a test liquid introduction step, measuring the amount of the test solution, and Introduced into the reaction tank; (2) a reagent introduction step of measuring an amount of a reagent for making the test solution acidic or alkaline, and introducing it into the reaction tank; (3) an oxidizing agent introduction step, Measuring an amount of the oxidizing agent for oxidizing the test solution and introducing it into the reaction tank; (4) an oxidation reaction step of heating the test solution and the oxidant in the reaction tank to cause the test solution to be subjected to a test solution Oxidation reaction at predetermined time (5) a reagent introduction step of measuring a quantity of a reaction reagent that reacts with the oxidizing agent and a titration reagent for the titration, and introducing the reaction reagent into the reaction tank; (6) an auxiliary liquid a introducing step of measuring an amount of the auxiliary liquid added to the test solution and introducing it into the reaction tank; (7) a titration step of titrating the test solution to which the auxiliary liquid is added in the reaction tank ; (8) an operation step of obtaining an amount of the oxidant consumed in the oxidation reaction from the end point of the titration, and calculating a relative amount of oxygen as a COD of the test solution; controlling the introduction step of the test solution, a liquid amount measured in each of the reagent introduction step, the oxidant introduction step, the reaction reagent introduction step, and the auxiliary liquid introduction step, so that the liquid surface position in the oxidation reaction step is located in the sample heating portion, and The liquid level position in the titration step is located at the upper portion of the detection surface of the electrode.

In the COD automatic measuring device having the above configuration, the area of the test liquid surface during heating can be reduced to reduce the amount of water evaporation. Further, since the area of the test liquid surface of the titration is enlarged, it is possible to ensure that there is sufficient space for the electrode to be inserted. Further, by introducing the auxiliary liquid, the heated test solution can be efficiently cooled.

According to a fourth aspect of the present invention, in the COD automatic measuring device, the electrode is composed of two platinum electrode elements, wherein the platinum electrode of the platinum electrode element has a flat surface to form a detection surface, and the detection is performed. The face is horizontally supported at the lower end of the electrode body.

According to a fifth aspect of the present invention, in the COD automatic measuring apparatus, the electrode is composed of two platinum electrode elements, wherein the platinum electrode of the platinum electrode element forms a detection surface in a flat shape, and the detection is performed. The face is horizontally supported at the lower end of the electrode body.

In the COD automatic measuring device, the depth of the liquid surface at the time of the titration can be made shallow, so that the amount of the waste liquid can be reduced.

The COD automatic measuring device according to any one of the first to fifth aspects, wherein the sample heating unit is immersed in Boil the water bath or in the oil bath.

In the COD automatic measuring device, since only the sample heating portion having the bottomed tubular shape is immersed in the boiling water bath or the oil bath, the water bath or the oil bath can be miniaturized, and the temperature can be reduced. Electricity.

According to the present invention, it is possible to provide a COD automatic measuring device capable of accurately performing measurement even when the amount of the test liquid is small, and can also satisfy the frequency of lowering the environmental load, the running cost, the recovery of the waste liquid and the replenishing agent, or the like. Demand for electricity consumption, etc.

1‧‧‧COD automatic measuring device

2‧‧‧Reaction tank

21‧‧‧Sample measurement department

22‧‧‧sample heating unit

23‧‧‧Draining tube

24‧‧‧ overflow pipe

25‧‧‧Test solution introduction tube

26‧‧‧Reagent introduction tube

27‧‧‧Reagent introduction tube

28‧‧‧Pure water inlet tube

29‧‧‧ Potassium Permanganate Introducer

3‧‧‧Measurement Department

4‧‧‧Storage Department

5‧‧‧Detection Department

50‧‧‧Platinum electrode components

502‧‧‧Detection surface

6‧‧‧Control Department

A‧‧‧The liquid level of the test solution in the oxidation reaction step

B‧‧‧ level of test solution in the titration step

1 is a functional block diagram of a COD automatic measuring device according to an embodiment of the present invention.

2 is a schematic view showing the structure of a reaction tank according to an embodiment of the present invention.

Fig. 3 is a flow chart showing the COD measurement according to an embodiment of the present invention.

The technical means adopted by the present invention for achieving the intended purpose of creation are further explained below in conjunction with the drawings and preferred embodiments of the present invention.

1 is a functional block diagram for explaining functions of the COD automatic measuring device 1 according to an embodiment of the present invention, wherein a solid line indicates a flow of a liquid such as a test solution or a reagent, and a broken line indicates a flow of an electric signal.

As shown in Fig. 1, the COD automatic measuring device 1 of the present embodiment includes a reaction tank 2 that stores a measured test solution and performs an operation from oxidation to titration, and a measuring unit 3 that tests the reagent, the reagent, and the pure water The storage unit 4 stores the reagent and the pure water, the detecting unit 5 performs titration, and detects the end point thereof, and the control unit 6 controls the entire apparatus and performs calculation. Further, the COD automatic measuring device 1 further includes a display unit, an input unit, and an output unit (not shown).

Here, the COD automatic measuring device 1 will be described as an apparatus for measuring COD according to the method of 17. "100-C potassium permanganate oxygen demand (COD _Mn )" according to JIS K 0102. That is, the test solution is made sulfuric acid, potassium permanganate is added as an oxidizing agent, and heated in a boiling water bath or an oil bath for 30 minutes to cause an oxidation reaction, and an excessive amount of sodium oxalate is added to stop the oxidation reaction, and the permanganic acid is then permeated. Potassium is titrated to determine the amount of oxidant consumed to determine the COD of the test solution.

Therefore, sulfuric acid is used as a reagent for making the test solution acidic, potassium permanganate is used as an oxidizing agent and a titration reagent, and sodium oxalate is used as a reaction reagent for reacting with an oxidizing agent and a titrant reagent.

As shown in FIG. 2, the reaction tank 2 includes a sample measuring unit 21 having an opening on the upper surface, and a sample heating unit 22 having a bottomed tubular shape and communicating with the bottom of the sample measuring unit 21, and Extend below. Further, the area of the horizontal cross section of the sample heating unit 22 is smaller than the area of the horizontal cross section of the sample measuring unit 21.

A liquid discharge pipe 23 is inserted into the sample heating unit 22, and the test solution or the cleaning liquid after the measurement can be discharged. Further, the reaction tank 2 is provided with an overflow pipe 24 to prevent liquid from leaking from the upper surface of the sample measuring unit 21.

The reaction tank 2 is inserted with a test solution introduction tube 25 for introducing a test solution, a reagent introduction tube 26 for introducing sulfuric acid, a reagent introduction tube 27 for introducing sodium oxalate, and a pure water introduction tube 28 for use. For import Pure water as an auxiliary liquid or a washing liquid; potassium permanganate introduction tube 29 for introducing potassium permanganate. In addition, two platinum electrode elements 50 are inserted for detecting the end point of the titration.

Further, the sample heating unit 22 of the reaction tank 2 is immersed in a boiling water bath or an oil bath (not shown), and the test liquid in the sample heating unit 22 can be heated.

The measuring unit 3 includes a test liquid measuring device, a sulfuric acid measuring device, a sodium oxalate measuring device, and a pure water measuring device for measuring a certain amount of the test liquid, sulfuric acid, sodium oxalate, and pure water (auxiliary liquid). A metering pump such as a syringe pump or a pulse pump can be used for each measuring device.

The upstream side of the test liquid measuring device is connected to a test solution extraction unit (not shown) by a pipe or a valve, and the downstream side is connected to the test liquid introduction pipe 25, and a certain amount of the test liquid can be measured and introduced into the reaction tank 2. .

The storage unit 4 includes a sulfuric acid storage tank, a sodium oxalate storage tank, a pure water storage tank, and a potassium permanganate storage tank for storing sulfuric acid, sodium oxalate, pure water, and potassium permanganate, respectively.

The sulfuric acid storage tank, the sodium oxalate storage tank, and the pure water storage tank are respectively connected to the above-described sulfuric acid measuring device, sodium oxalate measuring device, and pure water measuring device by piping or valves. Further, these measuring devices are respectively connected to the reagent introduction pipe 26, the reaction reagent introduction pipe 27, and the pure water introduction pipe 28, and a certain amount of sulfuric acid, sodium oxalate, and pure water (auxiliary liquid) can be introduced into the reaction tank 2.

Further, the potassium permanganate storage tank is connected to a titration pump provided in the detecting unit 5 to be described later.

The detecting unit 5 is provided with a titration pump for performing titration, and two platinum electrode elements 50 for detecting the end point of the titration.

The upstream side of the titration pump is connected to the potassium permanganate storage tank by a pipe or a valve, and the downstream side is connected to the potassium permanganate introduction pipe 29, and a certain amount of potassium permanganate can be measured and introduced into the reaction. In slot 2.

The platinum electrode element 50 has a flat plate-shaped platinum in the lower end portion of the electrode body made of a glass tube or the like. The platinum plate is horizontally disposed at a lower end portion of the electrode body to constitute a detection surface 502. Further, a silver wire is disposed inside the electrode body of the platinum electrode member 50 for electrically connecting the platinum plate to the outside.

The two platinum electrode elements 50 are subjected to the titration, and the detection surface 502 is located below the liquid surface of the test liquid, and a certain current flows between the detection surfaces 502 of the two platinum electrode elements 50. Therefore, the two detection surfaces 502 can be measured. The potential difference between them.

Since the detection surface 502 is formed of platinum which is horizontally disposed on the lower end portion of the electrode body and has a flat shape, the potential difference between the two detection surfaces 502 can be measured even if the depth of the liquid level is determined to be shallow. Therefore, the COD automatic measuring device 1 can reduce the amount of waste liquid.

The control unit 6 is constituted by a CPU, a storage device, or the like, and is capable of operating the device according to a program or setting stored in advance, or controlling the amount of liquid measured by each of the measuring devices or the titration pump, or measuring the potential difference of the platinum electrode member 50. The current split potential difference method is used to detect the end point of the titration to calculate the COD of the test solution.

Further, the program or setting stored in the control unit 6 can be changed by an input operation from the input unit as needed. Further, the control unit 6 itself can have a self-diagnosis function to change various settings at any time.

Thus, in the COD automatic measuring device 1, the test liquid introducing device The reagent introduction unit, the test solution measuring device, the test solution introduction tube 25, and the control unit 6; the reagent introduction device is composed of a sulfuric acid storage tank, a sulfuric acid measuring device, a reagent introduction tube 26, and a control unit 6; and the reaction reagent introduction device is composed of a sodium oxalate storage tank. The sodium oxalate measuring device, the reaction reagent introducing pipe 27, and the control unit 6 are configured. The auxiliary liquid introducing device is composed of a pure water storage tank, a pure water measuring device, a pure water introducing pipe 28, and a control unit 6.

Further, the oxidizing agent introduction device and the titration device are composed of a potassium permanganate storage tank, a titration pump, a potassium permanganate introduction pipe 29, and a control unit 6.

Further, in the COD automatic measuring device 1, it is preferable to provide a stirring device for stirring the test solution in the reaction tank 2. A stirring rod or a stirring blade may be inserted into the reaction tank 2. However, since the inner diameter of the sample heating portion 22 of the reaction tank 2 is narrow, it is preferable to connect the air pump to the upstream of the potassium permanganate introducing pipe 29, for example. The air is stirred.

Next, the COD measurement operation of this embodiment will be described with reference to the flowchart of Fig. 3 .

(Test solution introduction step)

When performing the COD measurement, the COD automatic measuring device 1 first performs a test liquid introduction step of measuring the test solution and introducing it into the reaction tank 2.

The introduction of the test solution is carried out through the above-described test solution introduction device. The test liquid measuring device measures the amount of the test liquid set in advance according to the instruction of the control unit 6, and introduces it into the reaction tank 2 through the test liquid introduction pipe 25.

At this time, as described in the following structure, a pump for a test liquid measuring device and a pump for a pure water measuring device can be shared. In other words, the test solution extraction unit (sample sink) and the syringe pump are connected by a pipe, in the test solution extraction unit and A reservoir is provided beside the sample extraction unit of the flow path between the injection pumps, a buffer tank is provided beside the syringe pump, and the test solution introduction tube 25 is connected to the flow path between the reservoir and the test solution extraction unit by a three-way solenoid valve. In addition, the pure water storage tank is connected to the flow path between the buffer tank and the injection pump by a three-way solenoid valve. Further, the pure water introduction pipe 28 is connected to the flow path between the buffer tank and the injection pump by an additional three-way solenoid valve. Then, the pure water is injected into the buffer tank, and the flow path of the test liquid introduction tube 25, the pure water storage tank, and the pure water introduction tube 28 of the three-way solenoid valve is closed, and the sample tank is sucked by the suction of the syringe pump. The test solution inside is introduced into the reservoir. Then, the flow path of the test solution introduction tube 25 is opened, and the test solution in the fixed amount of the solution tank is pushed out by the syringe pump. Through this operation, the measured test solution can be introduced into the reaction tank 2.

The amount (volume) of the test liquid measured in this step is smaller than the volume of the sample heating unit 22 of the reaction tank 2, that is, the liquid level of the test liquid introduced into the reaction tank 2 from the test solution introduction tube 25, and is located in the sample heating unit 22.

In addition, in this step, the test solution can also be diluted as needed. At this time, the diluted liquid level of the test solution is also controlled to be located in the sample heating unit 22.

(reagent introduction step)

Next, in the COD automatic measuring device 1, a reagent introduction step of measuring a reagent for making the test solution acidic, and introducing the reagent into the reaction tank 2 is performed.

The introduction of the reagent is carried out through the reagent introduction device described above. The reagent measuring device measures the amount of sulfuric acid set in advance according to an instruction from the control unit 6, and introduces it into the reaction tank 2 through the reagent introduction pipe 26.

(oxidant introduction step)

Next, oxidation is performed in the COD automatic measuring device 1. The agent introduction step of measuring an oxidizing agent for oxidizing the test solution is introduced into the reaction tank 2.

The introduction of the oxidizing agent is carried out through the above oxidizing agent introduction device. The titration pump measures the amount of potassium permanganate set in advance according to an instruction from the control unit 6, and introduces it into the reaction tank 2 through the potassium permanganate introduction tube 29.

(oxidation reaction step)

Next, in the COD automatic measuring device 1, an oxidation reaction step is performed in which the test solution and the oxidizing agent are heated in the reaction tank 2 to carry out an oxidation reaction for a predetermined time (here, 30 minutes).

The control unit 6 controls the amount of liquid measured in each of the steps of the test liquid introduction step, the reagent introduction step, and the oxidant introduction step, so that the liquid level of the test solution in the oxidation reaction step is located in the sample heating portion 22 (as shown in FIG. 2). A height).

In other words, the reaction tank 2 is configured such that the volume of the sample heating unit 22 is larger than the volume of the test liquid at the time of the oxidation reaction.

According to such a configuration, it is possible to reduce evaporation of water generated by the sample heating unit 22 from the outside during the heating of the test solution in the sample heating unit 22 by the boiling water bath or the oil bath. the amount. In addition, since the test solution is heated only in a portion of the volume of the sample heating portion 22 having the bottomed tube, only the portion of the sample heating portion 22 is immersed in the boiling water bath or the oil bath, so Reducing the miniaturization of water baths or oil baths to reduce power consumption.

(Reaction reagent introduction step)

Next, the reaction reagent introduction step is performed in the COD automatic measuring device 1, that is, the reaction for the reaction with the oxidizing agent and the titrating reagent is measured. The amount of the reagent is taken and introduced into the reaction tank 2.

The introduction of the reaction reagent is carried out through the above reagent introduction device. The reaction reagent measuring device measures the amount of sodium oxalate set in advance according to an instruction from the control unit 6, and introduces it into the reaction tank 2 through the reaction reagent introduction tube 27.

By adding sodium oxalate to the test solution, the oxidation reaction can be stopped, and the amount of the oxidizing agent consumed for the oxidation reaction for a predetermined period of time (here, 30 minutes) can be accurately determined. In addition, the end point of the titration can be more easily detected by adding an excess of sodium oxalate and titrating with potassium permanganate (reverse titration).

(Auxiliary fluid introduction step)

Next, the auxiliary liquid introduction step is performed in the COD automatic measuring device 1, that is, the auxiliary liquid (pure water) added to the test liquid is measured and introduced into the reaction tank 2.

The introduction of the auxiliary liquid is performed through the auxiliary liquid introduction device. The pure water measuring device measures the amount of pure water set in advance according to an instruction from the control unit 6, and introduces it into the reaction tank 2 through the pure water introduction pipe 28.

The control unit 6 controls the measured liquid amount of the auxiliary liquid so that the liquid level of the test liquid in the next titration step is located at the upper portion of the detection surface 502 of the platinum electrode member 50 in the sample measuring portion 21 (such as the B height shown in FIG. 2). ).

In other words, the reaction tank 2 is configured such that the volume of the sample heating unit 22 is smaller than the volume of the test liquid to which the auxiliary liquid is added.

With such a configuration, the liquid level of the titration test solution is located in the sample measurement unit 21 having a larger cross-sectional area than the sample heating unit 22, and the test solution can be ensured to be in contact with the inserted electrode. In addition, it can be effective by introducing auxiliary liquid The heated test solution is cooled.

(titration step)

Next, in the COD automatic measuring device 1, a titration step is performed in which the test solution to which the auxiliary liquid is added is titrated in the reaction tank 2.

The titration work is carried out through the above titration device. The titration pump measures the amount of potassium permanganate set in advance according to an instruction from the control unit 6, and introduces it into the reaction tank 2 through the potassium permanganate introduction pipe 29.

During the titration, a constant current flows between the detection faces 502 of the two platinum electrode elements 50, and the potential difference between the two detection faces 502 is measured. Then, the end point of the titration is detected according to a constant current classification potential difference method.

(operational steps)

Next, in the COD automatic measuring device 1, an arithmetic step is performed, and the amount of the oxidizing agent consumed in the oxidation reaction is obtained from the end point of the titration to further calculate the amount of oxygen opposed thereto as the COD of the test solution.

The calculation is performed by the control unit 6.

Further, in the COD automatic measuring device 1, the zero correction is performed by the zero correction liquid (pure water) and the measurement is performed based on the measurement of the measurement correction liquid (sodium oxalate) before the COD measurement. This allows for a more accurate COD measurement.

Further, in the COD automatic measuring device 1, when the test solution is rich in chloride ions, it is preferred to add silver nitrate as a masking agent to the test solution before the oxidizing agent introducing step. In this way, it is possible to prevent the potassium permanganate from reacting with the chloride ions and hindering the accurate progress of the titration.

In the COD automatic measuring device 1, the reaction tank 2 is cleaned after the above COD measurement. The cleaning solution can be sodium oxalate. If silver nitrate has been previously added as a masking agent, an ammonia solution can be used. After the reaction tank 2 was washed with these washing liquids, it was sufficiently rinsed with pure water.

The embodiments of the present invention have been described in detail above with reference to the drawings. In fact, the specific composition is not necessarily limited to the embodiment, and design changes made without departing from the spirit and scope of the invention are included. In other words, the COD automatic measuring device according to the present invention is characterized in that it includes a reaction tank having an opening on the upper surface thereof, and a sample measuring portion is formed, and is connected to the bottom portion of the sample measuring portion and extends downward. The bottomed tubular sample heating portion, the area of the horizontal cross section of the sample heating portion is smaller than the area of the horizontal cross section of the sample measuring portion, and the volume of the sample heating portion is larger than the volume of the test solution when the oxidation reaction occurs, and is smaller than The volume of the test solution to which the auxiliary liquid is added. Any embodiment may be included as long as it has the above technical features. For example, different reagents can also be used.

Example

An embodiment of the COD automatic measuring device 1 described above will be described.

In the reaction vessel 2 used in the present embodiment, the sample measuring portion 21 has an inner diameter of 41 mm and a height of 67 mm, and the sample heating portion 22 has an inner diameter of 12 mm and a height of 70 mm.

At this time, the liquid surface area at the time of heating (oxidation reaction step) of the test liquid is about 113 mm ² , which is about 1 21 of the liquid surface area (about 2375 mm ² ) of the prior art cylindrical reaction tank.

Moreover, the amount of test solution can be reduced from the prior art 100 mL Up to 5 mL, the amount of sulfuric acid can be reduced from 10 mL of the prior art to 0.5 mL, and the amount of potassium permanganate as an oxidizing agent can be reduced from 10 mL of the prior art to 0.5 mL, and the amount of sodium oxalate can be 10 mL from the prior art. By reducing to 0.5 mL, the amount of test solution, reagent, and waste liquid can be reduced to one-twentieth of the prior art (about 95% reduction).

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Although the present invention has been disclosed above in the preferred embodiments, it is not intended to limit the invention, and A person skilled in the art can make some modifications or modifications to equivalent embodiments by using the above-disclosed technical contents without departing from the technical scope of the present invention. The invention is not limited to any simple modifications, equivalent changes and modifications of the above embodiments.

Claims (5)

A chemical oxygen demand (COD) automatic measuring device, which adds an oxidizing agent to a certain amount of test liquid stored in a reaction tank, and heats it to perform an oxidation reaction for a predetermined time, and then obtains the oxidation reaction by titration. The amount of the oxidant is used to measure the COD of the test solution, wherein the apparatus comprises: a reaction tank in which a test solution introduction tube, a reagent introduction tube, a reagent introduction tube, a pure water introduction tube, and permanganic acid are inserted a potassium introduction tube having a sample measurement unit and a sample heating unit, wherein the sample measurement unit has an opening formed on the upper surface, and the sample heating unit has a bottomed tubular shape and communicates with the sample measurement unit. a bottom portion extending downward; an area of the horizontal cross section of the sample heating portion is smaller than an area of a horizontal cross section of the sample measuring portion, and a volume of the sample heating portion is larger than a volume of the test solution at the time of the oxidation reaction, and The volume of the sample heating unit is smaller than the volume of the test solution after the auxiliary liquid is added; and the detecting unit includes a titration pump and an electrode for detecting the end point of the titration, the electrode The opening is inserted into the sample measuring unit; the storage unit, wherein the storage unit includes a sulfuric acid storage tank, a sodium oxalate storage tank, a pure water storage tank, and a potassium permanganate storage tank, wherein the sulfuric acid storage tank, the The sodium oxalate storage tank and the pure water storage tank are respectively connected to the reagent introduction tube, the reaction reagent introduction tube, and the pure water introduction tube, and the potassium permanganate storage tank and the potassium permanganate are introduced. a tube and the titration pump connected; a control portion, the control portion comprising a CPU or a storage device; Wherein the auxiliary liquid introduction device includes the pure water storage tank, the pure water introduction pipe, and the control unit, and the auxiliary liquid introduction device measures a certain amount of addition after the oxidation reaction and before the titration The auxiliary liquid to the test solution is introduced into the reaction tank. The chemical oxygen demand automatic measuring device according to claim 1, wherein the electrode is composed of two platinum electrode members, wherein the platinum electrode of the platinum electrode member forms a detecting surface in a flat shape, and the detecting surface is horizontally The ground is supported at the lower end of the electrode body. An automatic oxygen demand measuring device for measuring COD of a test solution by adding an oxidizing agent to a test solution and heating it to perform an oxidation reaction, and then performing titration to determine the amount of the oxidant consumed during the oxidation reaction, thereby measuring the COD of the test solution. The reaction vessel includes a sample introduction tube, a reagent introduction tube, a reagent introduction tube, a pure water introduction tube, and a potassium permanganate introduction tube, and the reaction tank has a sample measurement unit and a sample heating unit. The sample measuring unit has an opening formed on the upper surface, and the sample heating unit has a bottomed tubular shape and communicates with the bottom of the sample measuring unit and extends downward; the area of the horizontal section of the sample heating portion is smaller than An area of a horizontal cross section of the sample measuring unit; an electrode inserted from the opening into the sample measuring unit for detecting an end point of the titration; a test solution extracting unit; and a detecting unit having a titration a storage unit having a sulfuric acid storage tank, a sodium oxalate storage tank, a pure water storage tank, and a potassium permanganate storage tank, wherein the sulfuric acid storage tank and the sodium oxalate storage tank Were introduced into the purified water storage tank with the reagent a tube, the reaction reagent introduction tube, and the pure water introduction tube are connected, the potassium permanganate storage tank is connected to the potassium permanganate introduction tube and the titration pump; and the control unit includes a CPU Or a storage device; the test solution introduction device includes the test solution extraction unit, the test solution introduction tube, and the control unit; and a reagent introduction device includes the sulfuric acid storage tank, the reagent introduction tube, and the control unit; The reagent introduction device includes the sodium oxalate storage tank, the reaction reagent introduction tube, and the control unit; and an auxiliary liquid introduction device including the pure water storage tank, the pure water introduction tube, and the control unit; The oxidant introduction device and a titration device include the potassium permanganate storage tank, the titration pump, the potassium permanganate introduction tube, and the control unit; the control unit sequentially performs the following steps: (1) a test solution introduction step of measuring the amount of the test solution and introducing it into the reaction tank; (2) a reagent introduction step of measuring an amount of a reagent for making the test solution acidic or alkaline, and introducing the same To the opposite (3) an oxidizing agent introduction step of measuring an amount of an oxidizing agent for oxidizing the test solution and introducing it into the reaction tank; (4) an oxidation reaction step of heating the reaction tank a test solution and the oxidant, the test solution is subjected to an oxidation reaction for a predetermined time; (5) a reagent introduction step of measuring a quantity of the reaction reagent reacted with the oxidant and the titration reagent for the titration, and the a reaction reagent is introduced into the reaction tank; (6) an auxiliary liquid introduction step, measuring an amount of the auxiliary liquid added to the test solution, and introducing the same into the reaction tank; (7) a titration step, at the The test solution to which the auxiliary liquid is added is titrated in the reaction tank; (8) the calculation step is to determine the amount of the oxidant consumed during the oxidation reaction from the end point of the titration, and calculate the relative oxygen amount. Taking the COD as the test solution; controlling the amount of liquid measured in each of the steps of the test liquid introduction step, the reagent introduction step, the oxidant introduction step, the reaction reagent introduction step, and the auxiliary liquid introduction step, so that the oxidation reaction step The liquid surface position is located in the sample heating portion, and the liquid surface position in the titration step is located at an upper portion of the detection surface of the electrode. The chemical oxygen demand automatic measuring device according to claim 3, wherein the electrode is composed of two platinum electrode members, wherein the platinum electrode of the platinum electrode member forms a detecting surface in a flat shape, and the detecting surface is horizontally The ground is supported at the lower end of the electrode body. The chemical oxygen demand automatic measuring device according to any one of claims 1 to 4, wherein the sample heating portion is immersed in a boiling water bath or in an oil bath.